Molecular simulation of small Knudsen number flows

NASA Astrophysics Data System (ADS)

Fei, Fei; Fan, Jing

2012-11-01

The direct simulation Monte Carlo (DSMC) method is a powerful particle-based method for modeling gas flows. It works well for relatively large Knudsen (Kn) numbers, typically larger than 0.01, but quickly becomes computationally intensive as Kn decreases due to its time step and cell size limitations. An alternative approach was proposed to relax or remove these limitations, based on replacing pairwise collisions with a stochastic model corresponding to the Fokker-Planck equation [J. Comput. Phys., 229, 1077 (2010); J. Fluid Mech., 680, 574 (2011)]. Similar to the DSMC method, the downside of that approach suffers from computationally statistical noise. To solve the problem, a diffusion-based information preservation (D-IP) method has been developed. The main idea is to track the motion of a simulated molecule from the diffusive standpoint, and obtain the flow velocity and temperature through sampling and averaging the IP quantities. To validate the idea and the corresponding model, several benchmark problems with Kn ˜ 10-3-10-4 have been investigated. It is shown that the IP calculations are not only accurate, but also efficient because they make possible using a time step and cell size over an order of magnitude larger than the mean collision time and mean free path, respectively.

Estimation of Knudsen diffusion coefficients from tracer experiments conducted with a binary gas system and a porous medium

NASA Astrophysics Data System (ADS)

Hibi, Yoshihiko; Kashihara, Ayumi

2018-03-01

A previous study has reported that Knudsen diffusion coefficients obtained by tracer experiments conducted with a binary gas system and a porous medium are consistently smaller than those obtained by permeability experiments conducted with a single-gas system and a porous medium. To date, however, that study is the only one in which tracer experiments have been conducted with a binary gas system. Therefore, to confirm this difference in Knudsen diffusion coefficients, we used a method we had developed previously to conduct tracer experiments with a binary carbon dioxide-nitrogen gas system and five porous media with permeability coefficients ranging from 10-13 to 10-11 m2. The results showed that the Knudsen diffusion coefficient of N2 (DN2) (cm2/s) was related to the effective permeability coefficient ke (m2) as DN2 = 7.39 × 107ke0.767. Thus, the Knudsen diffusion coefficients of N2 obtained by our tracer experiments were consistently 1/27 of those obtained by permeability experiments conducted with many porous media and air by other researchers. By using an inversion simulation to fit the advection-diffusion equation to the distribution of concentrations at observation points calculated by mathematically solving the equation, we confirmed that the method used to obtain the Knudsen diffusion coefficient in this study yielded accurate values. Moreover, because the Knudsen diffusion coefficient did not differ when columns with two different lengths, 900 and 1500 mm, were used, this column property did not influence the flow of gas in the column. The equation of the dusty gas model already includes obstruction factors for Knudsen diffusion and molecular diffusion, which relate to medium heterogeneity and tortuosity and depend only on the structure of the porous medium. Furthermore, there is no need to take account of any additional correction factor for molecular diffusion except the obstruction factor because molecular diffusion is only treated in a multicomponent

Ultrasound Attenuation in Normal Fluid 3He in 98% Aerogel: Knudsen-to-Hydrodynamic Crossover

NASA Astrophysics Data System (ADS)

Lee, Yoonseok; Choi, H. C.; Moon, B. H.; Masuhara, N.; Meisel, M. W.; Takeuchi, H.; Higashitani, S.; Nagai, K.; Mulders, N.

2014-03-01

Mass flow in porous media is a widely occurring phenomenon as in water flow in aquifers, blood flow in vessels, and petroleum flow through sandstones. However, the understanding of these phenomena is a challenging task. In particular, when the mean free path of the fluid particles exceeds the pore size, the hydrodynamic description breaks down and the fluid mass is carried by the Knudsen diffusion. The 3He-aerogel system offers an opportunity that allows a systematic investigation of a wide range flow phenomena from the hydrodynamic to Knudsen regime owing to the strongly temperature dependent mean free path in liquid 3He at low temperatures. In this paper, we present ultrasound attenuation measurements of liquid 3He in 98% aerogel. The Knudsen-hydrodynamic crossover is clearly demonstrated in a drastic change in the temperature dependence in attenuation observed in this system. H. Takeuchi et al., Phys. Rev. Lett. 108, 225307 (2012). Grant-in-Aid for Scientific Research No. 21540365 and No. 22103003 by MEXT of Japan and NSF DMR-0803516, DMR-0654118, and the State of Florida.

Estimation of Knudsen diffusion coefficients from tracer experiments conducted with a binary gas system and a porous medium.

PubMed

Hibi, Yoshihiko; Kashihara, Ayumi

2018-03-01

A previous study has reported that Knudsen diffusion coefficients obtained by tracer experiments conducted with a binary gas system and a porous medium are consistently smaller than those obtained by permeability experiments conducted with a single-gas system and a porous medium. To date, however, that study is the only one in which tracer experiments have been conducted with a binary gas system. Therefore, to confirm this difference in Knudsen diffusion coefficients, we used a method we had developed previously to conduct tracer experiments with a binary carbon dioxide-nitrogen gas system and five porous media with permeability coefficients ranging from 10 -13 to 10 -11  m 2 . The results showed that the Knudsen diffusion coefficient of N 2 (D N2 ) (cm 2 /s) was related to the effective permeability coefficient k e (m 2 ) as D N2  = 7.39 × 10 7 k e 0.767 . Thus, the Knudsen diffusion coefficients of N 2 obtained by our tracer experiments were consistently 1/27 of those obtained by permeability experiments conducted with many porous media and air by other researchers. By using an inversion simulation to fit the advection-diffusion equation to the distribution of concentrations at observation points calculated by mathematically solving the equation, we confirmed that the method used to obtain the Knudsen diffusion coefficient in this study yielded accurate values. Moreover, because the Knudsen diffusion coefficient did not differ when columns with two different lengths, 900 and 1500 mm, were used, this column property did not influence the flow of gas in the column. The equation of the dusty gas model already includes obstruction factors for Knudsen diffusion and molecular diffusion, which relate to medium heterogeneity and tortuosity and depend only on the structure of the porous medium. Furthermore, there is no need to take account of any additional correction factor for molecular diffusion except the obstruction factor because molecular diffusion is

High-temperature mass spectrometry - Vaporization of group 4-B metal carbides. [using Knudsen effusion

NASA Technical Reports Server (NTRS)

Stearns, C. A.; Kohl, F. J.

1974-01-01

The high temperature vaporization of the metal-carbon systems TiC, ZrC, HfC, and ThC was studied by the Knudsen effusion - mass spectrometric method. For each system the metal dicarbide and tetracarbide molecular species were identified in the gas phase. Relative ion currents of the carbides and metals were measured as a function of temperature. Second- and third-law methods were used to determine enthalpies. Maximum values were established for the dissociation energies of the metal monocarbide molecules TiC, ZrC, HfC, and ThC. Thermodynamic functions used in the calculations are discussed in terms of assumed molecular structures and electronic contributions to the partition functions. The trends shown by the dissociation energies of the carbides of Group 4B are compared with those of neighboring groups and discussed in relation to the corresponding oxides and chemical bonding. The high temperature molecular beam inlet system and double focusing mass spectrometer are described.

Microstructure actuation and gas sensing by the Knudsen thermal force

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strongrich, Andrew; Alexeenko, Alina, E-mail: alexeenk@purdue.edu

2015-11-09

The generation of forces and moments on structures immersed in rarefied non-isothermal gas flows has received limited practical implementation since first being discovered over a century ago. The formation of significant thermal stresses requires both large thermal gradients and characteristic dimensions which are comparable to the gas molecular mean free path. For macroscopic geometries, this necessitates impractically high temperatures and very low pressures. At the microscale, however, these conditions are easily achieved, allowing the effects to be exploited, namely, for gas-property sensing and microstructure actuation. In this letter, we introduce and experimentally evaluate performance of a microelectromechanical in-plane Knudsen radiometricmore » actuator, a self-contained device having Knudsen thermal force generation, sensing, and tuning mechanisms integrated onto the same platform. Sensitivity to ambient pressure, temperature gradient, as well as gas composition is demonstrated. Results are presented in terms of a non-dimensional force coefficient, allowing measurements to be directly compared to the previous experimental and computational data on out-of-plane cantilevered configurations.« less

A diffusive information preservation method for small Knudsen number flows

NASA Astrophysics Data System (ADS)

Fei, Fei; Fan, Jing

2013-06-01

The direct simulation Monte Carlo (DSMC) method is a powerful particle-based method for modeling gas flows. It works well for relatively large Knudsen (Kn) numbers, typically larger than 0.01, but quickly becomes computationally intensive as Kn decreases due to its time step and cell size limitations. An alternative approach was proposed to relax or remove these limitations, based on replacing pairwise collisions with a stochastic model corresponding to the Fokker-Planck equation [J. Comput. Phys., 229, 1077 (2010); J. Fluid Mech., 680, 574 (2011)]. Similar to the DSMC method, the downside of that approach suffers from computationally statistical noise. To solve the problem, a diffusion-based information preservation (D-IP) method has been developed. The main idea is to track the motion of a simulated molecule from the diffusive standpoint, and obtain the flow velocity and temperature through sampling and averaging the IP quantities. To validate the idea and the corresponding model, several benchmark problems with Kn ˜ 10-3-10-4 have been investigated. It is shown that the IP calculations are not only accurate, but also efficient because they make possible using a time step and cell size over an order of magnitude larger than the mean collision time and mean free path, respectively.

Financial Knudsen number: Breakdown of continuous price dynamics and asymmetric buy-and-sell structures confirmed by high-precision order-book information.

PubMed

Yura, Yoshihiro; Takayasu, Hideki; Sornette, Didier; Takayasu, Misako

2015-10-01

We generalize the description of the dynamics of the order book of financial markets in terms of a Brownian particle embedded in a fluid of incoming, exiting, and annihilating particles by presenting a model of the velocity on each side (buy and sell) independently. The improved model builds on the time-averaged number of particles in the inner layer and its change per unit time, where the inner layer is revealed by the correlations between price velocity and change in the number of particles (limit orders). This allows us to introduce the Knudsen number of the financial Brownian particle motion and its asymmetric version (on the buy and sell sides). Not being considered previously, the asymmetric Knudsen numbers are crucial in finance in order to detect asymmetric price changes. The Knudsen numbers allows us to characterize the conditions for the market dynamics to be correctly described by a continuous stochastic process. Not questioned until now for large liquid markets such as the USD-JPY and EUR-USD exchange rates, we show that there are regimes when the Knudsen numbers are so high that discrete particle effects dominate, such as during market stresses and crashes. We document the presence of imbalances of particles depletion rates on the buy and sell sides that are associated with high Knudsen numbers and violent directional price changes. This indicator can detect the direction of the price motion at the early stage while the usual volatility risk measure is blind to the price direction.

Financial Knudsen number: Breakdown of continuous price dynamics and asymmetric buy-and-sell structures confirmed by high-precision order-book information

NASA Astrophysics Data System (ADS)

Yura, Yoshihiro; Takayasu, Hideki; Sornette, Didier; Takayasu, Misako

2015-10-01

We generalize the description of the dynamics of the order book of financial markets in terms of a Brownian particle embedded in a fluid of incoming, exiting, and annihilating particles by presenting a model of the velocity on each side (buy and sell) independently. The improved model builds on the time-averaged number of particles in the inner layer and its change per unit time, where the inner layer is revealed by the correlations between price velocity and change in the number of particles (limit orders). This allows us to introduce the Knudsen number of the financial Brownian particle motion and its asymmetric version (on the buy and sell sides). Not being considered previously, the asymmetric Knudsen numbers are crucial in finance in order to detect asymmetric price changes. The Knudsen numbers allows us to characterize the conditions for the market dynamics to be correctly described by a continuous stochastic process. Not questioned until now for large liquid markets such as the USD-JPY and EUR-USD exchange rates, we show that there are regimes when the Knudsen numbers are so high that discrete particle effects dominate, such as during market stresses and crashes. We document the presence of imbalances of particles depletion rates on the buy and sell sides that are associated with high Knudsen numbers and violent directional price changes. This indicator can detect the direction of the price motion at the early stage while the usual volatility risk measure is blind to the price direction.

Double-layered cell transfer technology for bone regeneration

PubMed Central

Akazawa, Keiko; Iwasaki, Kengo; Nagata, Mizuki; Yokoyama, Naoki; Ayame, Hirohito; Yamaki, Kazumasa; Tanaka, Yuichi; Honda, Izumi; Morioka, Chikako; Kimura, Tsuyoshi; Komaki, Motohiro; Kishida, Akio; Izumi, Yuichi; Morita, Ikuo

2016-01-01

For cell-based medicine, to mimic in vivo cellular localization, various tissue engineering approaches have been studied to obtain a desirable arrangement of cells on scaffold materials. We have developed a novel method of cell manipulation called “cell transfer technology”, enabling the transfer of cultured cells onto scaffold materials, and controlling cell topology. Here we show that using this technique, two different cell types can be transferred onto a scaffold surface as stable double layers or in patterned arrangements. Various combinations of adherent cells were transferred to a scaffold, amniotic membrane, in overlapping bilayers (double-layered cell transfer), and transferred cells showed stability upon deformations of the material including folding and trimming. Transplantation of mesenchymal stem cells from periodontal ligaments (PDLSC) and osteoblasts, using double-layered cell transfer significantly enhanced bone formation, when compared to single cell type transplantation. Our findings suggest that this double-layer cell transfer is useful to produce a cell transplantation material that can bear two cell layers. Moreover, the transplantation of an amniotic membrane with PDLSCs/osteoblasts by cell transfer technology has therapeutic potential for bone defects. We conclude that cell transfer technology provides a novel and unique cell transplantation method for bone regeneration. PMID:27624174

Investigating the validity of the Knudsen prescription for diffusivities in a mesoporous covalent organic framework

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krishna, Rajamani; van Baten, Jasper M.

2011-04-27

Molecular dynamics (MD) simulations were performed to determine the self-diffusivity (D i,self) and the Maxwell–Stefan diffusivity (Ð I) of hydrogen, argon, carbon dioxide, methane, ethane, propane, n-butane, n-pentane, and n-hexane in BTP-COF, which is a covalent organic framework (COF) that has one-dimensional 3.4-nm-sized channels. The MD simulations show that the zero-loading diffusivity (Ð I(0)) is consistently lower, by up to a factor of 10, than the Knudsen diffusivity (D i,Kn) values. The ratio Ð I(0)/D i,Kn is found to correlate with the isosteric heat of adsorption, which, in turn, is a reflection of the binding energy for adsorption on themore » pore walls: the stronger the binding energy, the lower the ratio Ð I(0)/D i,Kn. The diffusion selectivity, which is defined by the ratio D 1,self/D 2,self for binary mixtures, was determined to be significantly different from the Knudsen selectivity (M 2/M 1) 1/2, where M I is the molar mass of species i. For mixtures in which component 2 is more strongly adsorbed than component 1, the expression (D 1,self/D 2,self)/(M 2/M 1)1/2 has values in the range of 1–10; the departures from the Knudsen selectivity increased with increasing differences in adsorption strengths of the constituent species. The results of this study have implications in the modeling of diffusion within mesoporous structures, such as MCM-41 and SBA-15.« less

Vaporization Studies of Olivine via Knudsen Effusion Mass Spectrometry

NASA Technical Reports Server (NTRS)

Costa, G. C. C.; Jacobson, N. S.

2014-01-01

Olivine is the major mineral in the Earth's upper mantle occurring predominantly in igneous rocks and has been identified in meteorites, asteroids, the Moon and Mars. Among many other important applications in planetary and materials sciences, the thermodynamic properties of vapor species from olivine are crucial as input parameters in computational modelling of the atmospheres of hot, rocky exoplanets (lava planets). There are several weight loss studies of olivine vaporization in the literature and one Knudsen Effusion Mass Spectrometry (KEMS) study. In this study, we examine a forsterite-rich olivine (93% forsterite and 7% fayalite, Fo93Fa7) with KEMS to further understand its vaporization and thermodynamic properties.

A double-spike method for K-Ar measurement: A technique for high precision in situ dating on Mars and other planetary surfaces

NASA Astrophysics Data System (ADS)

Farley, K. A.; Hurowitz, J. A.; Asimow, P. D.; Jacobson, N. S.; Cartwright, J. A.

2013-06-01

A new method for K-Ar dating using a double isotope dilution technique is proposed and demonstrated. The method is designed to eliminate known difficulties facing in situ dating on planetary surfaces, especially instrument complexity and power availability. It may also have applicability in some terrestrial dating applications. Key to the method is the use of a solid tracer spike enriched in both 39Ar and 41K. When mixed with lithium borate flux in a Knudsen effusion cell, this tracer spike and a sample to be dated can be successfully fused and degassed of Ar at <1000 °C. The evolved 40Ar∗/39Ar ratio can be measured to high precision using noble gas mass spectrometry. After argon measurement the sample melt is heated to a slightly higher temperature (˜1030 °C) to volatilize potassium, and the evolved 39K/41K ratio measured by Knudsen effusion mass spectrometry. Combined with the known composition of the tracer spike, these two ratios define the K-Ar age using a single sample aliquot and without the need for extreme temperature or a mass determination. In principle the method can be implemented using a single mass spectrometer. Experiments indicate that quantitative extraction of argon from a basalt sample occurs at a sufficiently low temperature that potassium loss in this step is unimportant. Similarly, potassium isotope ratios measured in the Knudsen apparatus indicate good sample-spike equilibration and acceptably small isotopic fractionation. When applied to a flood basalt from the Viluy Traps, Siberia, a K-Ar age of 351 ± 19 Ma was obtained, a result within 1% of the independently known age. For practical reasons this measurement was made on two separate mass spectrometers, but a scheme for combining the measurements in a single analytical instrument is described. Because both parent and daughter are determined by isotope dilution, the precision on K-Ar ages obtained by the double isotope dilution method should routinely approach that of a pair of

Clinical Significance of "Double-hit" and "Double-protein" expression in Primary Gastric B-cell Lymphomas.

PubMed

He, Miaoxia; Chen, Keting; Li, Suhong; Zhang, Shimin; Zheng, Jianming; Hu, Xiaoxia; Gao, Lei; Chen, Jie; Song, Xianmin; Zhang, Weiping; Wang, Jianmin; Yang, Jianmin

2016-01-01

Primary gastric B-cell lymphoma is the second most common malignancy of the stomach. There are many controversial issues about its diagnosis, treatment and clinical management. "Double-hit" and "double-protein" involving gene rearrangement and protein expression of c-Myc and bcl2/bcl6 are the most used terms to describe DLBCL poor prognostic factors in recent years. However, very little is known about the role of these prognostic factors in primary gastric B-cell lymphomas. This study aims to obtain a molecular pathology prognostic model of gastric B-cell lymphoma for clinical stratified management by evaluating how the "double-hit" and "double-protein" in tumor cells as well as microenvironmental reaction of tumor stromal tissue affect clinical outcome in primary gastric B-cell lymphomas. Data and tissues of 188 cases diagnosed with gastric B-cell lymphomas were used in this study. Tumor tissue microarray (TMA) of formalin fixed and paraffin embedded (FFPE) tissues was constructed for fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) analysis with a serial of biomarkers containing MYC, BCL2, BCL6, CD31, SPARC, CD10, MUM1 and Ki-67. Modeled period analysis was used to estimate 3-year and 5-year overall survival (OS) and disease-free survival (DFS) distributions. There was no definite "double-hit" case though the gene rearrangement of c-Myc (5.9%), bcl2 (0.1%) and bcl6 (7.4%) was found in gastric B-cell lymphomas. The gene amplification or copy gains of c-Myc (10.1%), bcl-2 (17.0%) and bcl-6 (0.9%) were present in these lymphomas. There were 12 cases of the lymphomas with the "double-protein" expression of MYC and BCL2/BCL6. All patients with "double-protein" gastric B-cell lymphomas had poor outcome compared with those without. More importantly, "MYC-BCL2-BCL6" negative group of gastric B-cell lymphoma patients had favorable clinical outcome regardless clinical stage, pathological types and therapeutic modalities. And the similar better

Generalized Knudsen Number for Unsteady Fluid Flow.

PubMed

Kara, V; Yakhot, V; Ekinci, K L

2017-02-17

We explore the scaling behavior of an unsteady flow that is generated by an oscillating body of finite size in a gas. If the gas is gradually rarefied, the Navier-Stokes equations begin to fail and a kinetic description of the flow becomes more appropriate. The failure of the Navier-Stokes equations can be thought to take place via two different physical mechanisms: either the continuum hypothesis breaks down as a result of a finite size effect or local equilibrium is violated due to the high rate of strain. By independently tuning the relevant linear dimension and the frequency of the oscillating body, we can experimentally observe these two different physical mechanisms. All the experimental data, however, can be collapsed using a single dimensionless scaling parameter that combines the relevant linear dimension and the frequency of the body. This proposed Knudsen number for an unsteady flow is rooted in a fundamental symmetry principle, namely, Galilean invariance.

Generalized Knudsen Number for Unsteady Fluid Flow

NASA Astrophysics Data System (ADS)

Kara, V.; Yakhot, V.; Ekinci, K. L.

2017-02-01

We explore the scaling behavior of an unsteady flow that is generated by an oscillating body of finite size in a gas. If the gas is gradually rarefied, the Navier-Stokes equations begin to fail and a kinetic description of the flow becomes more appropriate. The failure of the Navier-Stokes equations can be thought to take place via two different physical mechanisms: either the continuum hypothesis breaks down as a result of a finite size effect or local equilibrium is violated due to the high rate of strain. By independently tuning the relevant linear dimension and the frequency of the oscillating body, we can experimentally observe these two different physical mechanisms. All the experimental data, however, can be collapsed using a single dimensionless scaling parameter that combines the relevant linear dimension and the frequency of the body. This proposed Knudsen number for an unsteady flow is rooted in a fundamental symmetry principle, namely, Galilean invariance.

2d Granular Gas in Knudsen Regime and in Microgravity Excited by Vibration: Velocity and Position Distributions

NASA Astrophysics Data System (ADS)

Hou, M.; Liu, R.; Li, Y.; Lu, K.; Garrabos, Y.; Evesque, P.

2009-06-01

Dynamics of quasi-2d dissipative granular gas is studied in microgravity condition (of the order of 10-4 g) in the limit of Knudsen regime. The gas, made of 4 spheres, is confined in a square cell enforced to follow linear sinusoidal vibration in ten different vibration modes. The trajectory of one of the particles is tracked and reconstructed from the 2-hour video data. From statistical analysis, we find that (i) loss due to wall friction is small, (ii) trajectory looks ergodic in space, and (iii) distribution ρ(v) of speed follows an exponential distribution, i.e. ρ(v)≈exp(-v/vxo,yo), with vxo,yo being a characteristic velocity along a direction parallel (y) or perpendicular (x) to vibration direction. This law deviates strongly from the Boltzmann distribution of speed in molecular gas. Comparisons of this result with previous measurements in earth environment, and what was found in 3d cell [1] performed in 10-2 g environment are given.

Normal stress effects on Knudsen flow

NASA Astrophysics Data System (ADS)

Eu, Byung Chan

2018-01-01

Normal stress effects are investigated on tube flow of a single-component non-Newtonian fluid under a constant pressure gradient in a constant temperature field. The generalized hydrodynamic equations are employed, which are consistent with the laws of thermodynamics. In the cylindrical tube flow configuration, the solutions of generalized hydrodynamic equations are exactly solvable and the flow velocity is obtained in a simple one-dimensional integral quadrature. Unlike the case of flow in the absence of normal stresses, the flow develops an anomaly in that the flow in the boundary layer becomes stagnant and the thickness of such a stagnant velocity boundary layer depends on the pressure gradient, the aspect ratio of the radius to the length of the tube, and the pressure (or density and temperature) at the entrance of the tube. The volume flow rate formula through the tube is derived for the flow. It generalizes the Knudsen flow rate formula to the case of a non-Newtonian stress tensor in the presence of normal stress differences. It also reduces to the Navier-Stokes theory formula in the low shear rate limit near equilibrium.

Double-double bend achromat cell upgrade at the Diamond Light Source: From design to commissioning

NASA Astrophysics Data System (ADS)

Bartolini, R.; Abraham, C.; Apollonio, M.; Bailey, C. P.; Cox, M. P.; Day, A.; Fielder, R. T.; Hammond, N. P.; Heron, M. T.; Holdsworth, R.; Kay, J.; Martin, I. P. S.; Mhaskar, S.; Miller, A.; Pulampong, T.; Rehm, G.; Rial, E. C. M.; Rose, A.; Shahveh, A.; Singh, B.; Thomson, A.; Walker, R. P.

2018-05-01

Diamond has recently successfully commissioned a major change in the lattice consisting of the substitution of a standard double-bend achromat (DBA) cell with a modified four-bend achromat (4BA) cell called "double-double bend achromat" (DDBA). This work stems from the original studies initiated in 2012 towards a Diamond upgrade and provides the benefit of an additional straight section in the ring available for insertion devices. This paper reviews the DDBA design and layout, the implications for technical subsystems, the associated engineering challenges and the main results of the commissioning completed in April 2017.

Knudsen pump produced via silicon deep RIE, thermal oxidation, and anodic bonding processes for on-chip vacuum pumping

NASA Astrophysics Data System (ADS)

Van Toan, Nguyen; Inomata, Naoki; Trung, Nguyen Huu; Ono, Takahito

2018-05-01

This work describes the fabrication and evaluation of the Knudsen pump for on-chip vacuum pumping that works based on the principle of a thermal transpiration. Three AFM (atomic force microscope) cantilevers are integrated into small chambers with a size of 5 mm  ×  3 mm  ×  0.4 mm for the pump’s evaluation. Knudsen pump is fabricated using deep RIE (reactive ion etching), wet thermal oxidation and anodic bonding processes. The fabricated device is evaluated by monitoring the quality (Q) factor of the integrated cantilevers. The Q factor of the cantilever is increased from 300 -1150 in cases without and with a temperature difference approximately 25 °C between the top (the hot side at 40 °C) and bottom (the cold side at 15 °C) sides of the fabricated device, respectively. The evacuated chamber pressure of around 10 kPa is estimated from the Q factor of the integrated cantilevers.

Knudsen temperature jump and the Navier-Stokes hydrodynamics of granular gases driven by thermal walls.

PubMed

Khain, Evgeniy; Meerson, Baruch; Sasorov, Pavel V

2008-10-01

Thermal wall is a convenient idealization of a rapidly vibrating plate used for vibrofluidization of granular materials. The objective of this work is to incorporate the Knudsen temperature jump at thermal wall in the Navier-Stokes hydrodynamic modeling of dilute granular gases of monodisperse particles that collide nearly elastically. The Knudsen temperature jump manifests itself as an additional term, proportional to the temperature gradient, in the boundary condition for the temperature. Up to a numerical prefactor O(1) , this term is known from kinetic theory of elastic gases. We determine the previously unknown numerical prefactor by measuring, in a series of molecular dynamics (MD) simulations, steady-state temperature profiles of a gas of elastically colliding hard disks, confined between two thermal walls kept at different temperatures, and comparing the results with the predictions of a hydrodynamic calculation employing the modified boundary condition. The modified boundary condition is then applied, without any adjustable parameters, to a hydrodynamic calculation of the temperature profile of a gas of inelastic hard disks driven by a thermal wall. We find the hydrodynamic prediction to be in very good agreement with MD simulations of the same system. The results of this work pave the way to a more accurate hydrodynamic modeling of driven granular gases.

Cartilage formation in the CELLS 'double bubble' hardware

NASA Technical Reports Server (NTRS)

Duke, P. J.; Arizpe, Jorge; Montufar-Solis, Dina

1991-01-01

The CELLS experiment scheduled to be flown on the first International Microgravity Laboratory is designed to study the effect of microgravity on the cartilage formation, by measuring parameters of growth in a differentiating cartilage cell culture. This paper investigates the conditions for this experiment by studying cartilage differentiation in the 'bubble exchange' hardware with the 'double bubble' design in which the bubbles are joined by a flange which also overlays the gasket. Four types of double bubbles (or double gas permeable membranes) were tested: injection-molded bubbles 0.01- and 0.005-in. thick, and compression molded bubbles 0.015- and 0.01-in. thick. It was found that double bubble membranes of 0.005- and 0.010-in. thickness supported cartilage differentiation, while the 0.015-in. bubbles did not. It was also found that nodule count, used in this study as a parameter, is not the best measure of the amount of cartilage differentiation.

Increasing cell culture population doublings for long-term growth of finite life span human cell cultures

DOEpatents

Stampfer, Martha R.; Garbe, James C.

2016-06-28

Cell culture media formulations for culturing human epithelial cells are herein described. Also described are methods of increasing population doublings in a cell culture of finite life span human epithelial cells and prolonging the life span of human cell cultures. Using the cell culture media disclosed alone and in combination with addition to the cell culture of a compound associated with anti-stress activity achieves extended growth of pre-stasis cells and increased population doublings and life span in human epithelial cell cultures.

Increasing cell culture population doublings for long-term growth of finite life span human cell cultures

DOEpatents

Stampfer, Martha R; Garbe, James C

2015-02-24

Cell culture media formulations for culturing human epithelial cells are herein described. Also described are methods of increasing population doublings in a cell culture of finite life span human epithelial cells and prolonging the life span of human cell cultures. Using the cell culture media disclosed alone and in combination with addition to the cell culture of a compound associated with anti-stress activity achieves extended growth of pre-stasis cells and increased population doublings and life span in human epithelial cell cultures.

Linearized-moment analysis of the temperature jump and temperature defect in the Knudsen layer of a rarefied gas.

PubMed

Gu, Xiao-Jun; Emerson, David R

2014-06-01

Understanding the thermal behavior of a rarefied gas remains a fundamental problem. In the present study, we investigate the predictive capabilities of the regularized 13 and 26 moment equations. In this paper, we consider low-speed problems with small gradients, and to simplify the analysis, a linearized set of moment equations is derived to explore a classic temperature problem. Analytical solutions obtained for the linearized 26 moment equations are compared with available kinetic models and can reliably capture all qualitative trends for the temperature-jump coefficient and the associated temperature defect in the thermal Knudsen layer. In contrast, the linearized 13 moment equations lack the necessary physics to capture these effects and consistently underpredict kinetic theory. The deviation from kinetic theory for the 13 moment equations increases significantly for specular reflection of gas molecules, whereas the 26 moment equations compare well with results from kinetic theory. To improve engineering analyses, expressions for the effective thermal conductivity and Prandtl number in the Knudsen layer are derived with the linearized 26 moment equations.

Numerical analysis of thermal creep flow in curved channels for designing a prototype of Knudsen micropump

NASA Astrophysics Data System (ADS)

Leontidis, V.; Brandner, J. J.; Baldas, L.; Colin, S.

2012-05-01

The possibility to generate a gas flow inside a channel just by imposing a tangential temperature gradient along the walls without the existence of an initial pressure difference is well known. The gas must be under rarefied conditions, meaning that the system must operate between the slip and the free molecular flow regimes, either at low pressure or/and at micro/nano-scale dimensions. This phenomenon is at the basis of the operation principle of Knudsen pumps, which are actually compressors without any moving parts. Nowadays, gas flows in the slip flow regime through microchannels can be modeled using commercial Computational Fluid Dynamics softwares, because in this regime the compressible Navier-Stokes equations with appropriate boundary conditions are still valid. A simulation procedure has been developed for the modeling of thermal creep flow using ANSYS Fluent®. The implementation of the boundary conditions is achieved by developing User Defined Functions (UDFs) by means of C++ routines. The complete first order velocity slip boundary condition, including the thermal creep effects due to the axial temperature gradient and the effect of the wall curvature, and the temperature jump boundary condition are applied. The developed simulation tool is used for the preliminary design of Knudsen micropumps consisting of a sequence of curved and straight channels.

Comment on "Heat transfer and fluid flow in microchannels and nanochannels at high Knudsen number using thermal lattice-Boltzmann method".

PubMed

Luo, Li-Shi

2011-10-01

In this Comment we reveal the falsehood of the claim that the lattice Bhatnagar-Gross-Krook (BGK) model "is capable of modeling shear-driven, pressure-driven, and mixed shear-pressure-driven rarified [sic] flows and heat transfer up to Kn=1 in the transitional regime" made in a recent paper [Ghazanfarian and Abbassi, Phys. Rev. E 82, 026307 (2010)]. In particular, we demonstrate that the so-called "Knudsen effects" described are merely numerical artifacts of the lattice BGK model and they are unphysical. Specifically, we show that the erroneous results for the pressure-driven flow in a microchannel imply the false and unphysical condition that 6σKn<-1, where Kn is the Knudsen number σ=(2-σ(v))/σ(v) and σ(v)∈(0,1] is the tangential momentum accommodation coefficient. We also show explicitly that the defects of the lattice BGK model can be completely removed by using the multiple-relaxation-time collision model.

Parallel Fokker–Planck-DSMC algorithm for rarefied gas flow simulation in complex domains at all Knudsen numbers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Küchlin, Stephan, E-mail: kuechlin@ifd.mavt.ethz.ch; Jenny, Patrick

2017-01-01

A major challenge for the conventional Direct Simulation Monte Carlo (DSMC) technique lies in the fact that its computational cost becomes prohibitive in the near continuum regime, where the Knudsen number (Kn)—characterizing the degree of rarefaction—becomes small. In contrast, the Fokker–Planck (FP) based particle Monte Carlo scheme allows for computationally efficient simulations of rarefied gas flows in the low and intermediate Kn regime. The Fokker–Planck collision operator—instead of performing binary collisions employed by the DSMC method—integrates continuous stochastic processes for the phase space evolution in time. This allows for time step and grid cell sizes larger than the respective collisionalmore » scales required by DSMC. Dynamically switching between the FP and the DSMC collision operators in each computational cell is the basis of the combined FP-DSMC method, which has been proven successful in simulating flows covering the whole Kn range. Until recently, this algorithm had only been applied to two-dimensional test cases. In this contribution, we present the first general purpose implementation of the combined FP-DSMC method. Utilizing both shared- and distributed-memory parallelization, this implementation provides the capability for simulations involving many particles and complex geometries by exploiting state of the art computer cluster technologies.« less

An experimental study of chondrule formation from chondritic precursors via evaporation and condensation in Knudsen cell: Shock heating model of dust aggregates

NASA Astrophysics Data System (ADS)

Imae, Naoya; Isobe, Hiroshi

2017-09-01

Chondrules, igneous objects of ∼1 mm in diameter, formed in the earliest solar system via a transient heating event, are divided into two types: main (type I, FeO-poor) and minor (type II, FeO-rich). Using various chondritic materials for different redox conditions and grain sizes, chondrule reproduction experiments were carried out at IW-2 to IW-3.8, with cooling rates mainly ∼100°C/h, with peak temperatures mainly at 1450 °C, and mainly at 100 Pa in a Knudsen cell providing near chemical equilibrium between the charge and the surrounding gas at the peak temperatures. Vapor pressures in the capsule were controlled using solid buffers. After and during the significant evaporation of the iron component from the metallic iron-poor starting materials in near equilibrium, crystallization occurred. This resulted in the formation of a product similar to the type I chondrules. Dusty olivine grains occurred in charges that had precursor type II chondrules containing coarse ferroan olivine, but such grains are not common in type I chondrules. Therefore fine-grained ferroan matrices rather than type II chondrules are main precursor for type I chondrules. The type I chondrules would have evolved via evaporation and condensation in the similar conditions to the present experimental system. Residual gas, which escaped in experiments, could have condensed to form matrices, leading to complementary compositions. Clusters of matrices and primordial chondrules could have been recycled to form main-generation chondrules originated from the shock heating.

High-rate lithium/manganese dioxide batteries; the double cell concept

NASA Astrophysics Data System (ADS)

Drews, Jürgen; Wolf, Rüdiger; Fehrmann, Gerd; Staub, Roland

An implantable defibrillator battery has to provide pulse-power capabilities as well as high energy density. Low self-discharge rates are mandatory and an ability to check the state of charge is required. To accomplish these requirements, a lithium/manganese dioxide battery with a modified active cathode mass has been developed. Usage of a double cell design increases significantly the battery performance within an implantable defibrillator. The design features of a high-rate, pulse-power, manganese dioxide double cell are described.

Vapor Pressure of Three Brominated Flame Retardants Determined via Knudsen Effusion Method

PubMed Central

Fu, Jinxia; Suuberg, Eric M.

2012-01-01

Brominated flame retardants (BFRs) have been used in a variety of consumer products in the past four decades. The vapor pressures for three widely used BFRs, that is, tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), and octabromodiphenyl ethers (octaBDEs) mixtures, were determined using the Knudsen effusion method and compared to those of decabromodiphenyl ether (BDE209). The values measured extrapolated to 298.15 K are 8.47 × 10−9, 7.47 × 10−10, and 2.33 × 10−9 Pa, respectively. The enthalpies of sublimation for these BFRs were estimated using the Clausius-Clapeyron equation and are 143.6 ± 0.4, 153.7 ± 3.1, and 150.8 ± 3.2 kJ/mole, respectively. In addition, the enthalpies of fusion and melting temperatures for these BFRs were also measured in the present study. PMID:22213441

Synergetic effect of double-step blocking layer for the perovskite solar cell

NASA Astrophysics Data System (ADS)

Kim, Jinhyun; Hwang, Taehyun; Lee, Sangheon; Lee, Byungho; Kim, Jaewon; Kim, Jaewook; Gil, Bumjin; Park, Byungwoo

2017-10-01

In an organometallic CH3NH3PbI3 (MAPbI3) perovskite solar cell, we have demonstrated a vastly compact TiO2 layer synthesized by double-step deposition, through a combination of sputter and solution deposition to minimize the electron-hole recombination and boost the power conversion efficiency. As a result, the double-step strategy allowed outstanding transmittance of blocking layer. Additionally, crystallinity and morphology of the perovskite film were significantly modified, provoking enhanced photon absorption and solar cell performance with the reduced recombination rate. Thereby, this straightforward double-step strategy for the blocking layer exhibited 12.31% conversion efficiency through morphological improvements of each layer.

One-Cell Doubling Evaluation by Living Arrays of Yeast, ODELAY!

DOE PAGES

Herricks, Thurston; Dilworth, David J.; Mast, Fred D.; ...

2016-11-16

Cell growth is a complex phenotype widely used in systems biology to gauge the impact of genetic and environmental perturbations. Due to the magnitude of genome-wide studies, resolution is often sacrificed in favor of throughput, creating a demand for scalable, time-resolved, quantitative methods of growth assessment. We present ODELAY (One-cell Doubling Evaluation by Living Arrays of Yeast), an automated and scalable growth analysis platform. High measurement density and single-cell resolution provide a powerful tool for large-scale multiparameter growth analysis based on the modeling of microcolony expansion on solid media. Pioneered in yeast but applicable to other colony forming organisms, ODELAYmore » extracts the three key growth parameters (lag time, doubling time, and carrying capacity) that define microcolony expansion from single cells, simultaneously permitting the assessment of population heterogeneity. The utility of ODELAY is illustrated using yeast mutants, revealing a spectrum of phenotypes arising from single and combinatorial growth parameter perturbations.« less

One-Cell Doubling Evaluation by Living Arrays of Yeast, ODELAY!

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herricks, Thurston; Dilworth, David J.; Mast, Fred D.

Cell growth is a complex phenotype widely used in systems biology to gauge the impact of genetic and environmental perturbations. Due to the magnitude of genome-wide studies, resolution is often sacrificed in favor of throughput, creating a demand for scalable, time-resolved, quantitative methods of growth assessment. We present ODELAY (One-cell Doubling Evaluation by Living Arrays of Yeast), an automated and scalable growth analysis platform. High measurement density and single-cell resolution provide a powerful tool for large-scale multiparameter growth analysis based on the modeling of microcolony expansion on solid media. Pioneered in yeast but applicable to other colony forming organisms, ODELAYmore » extracts the three key growth parameters (lag time, doubling time, and carrying capacity) that define microcolony expansion from single cells, simultaneously permitting the assessment of population heterogeneity. The utility of ODELAY is illustrated using yeast mutants, revealing a spectrum of phenotypes arising from single and combinatorial growth parameter perturbations.« less

Generalized Knudsen Number for Oscillatory Flows Generated by MEMS and NEMS Resonators

NASA Astrophysics Data System (ADS)

Ekinci, Kamil; Kara, Vural; Yakhot, Victor

2017-11-01

We have explored the scaling behavior of oscillatory flows that are generated by the oscillations of MEMS and NEMS resonators in a gas. If the gas is gradually rarefied, the Navier-Stokes equations begin to fail and a kinetic description of the flow becomes more appropriate. The failure of the Navier-Stokes equations can be thought to take place via two different physical mechanisms: either the continuum hypothesis breaks down as a result of a finite size effect; or local equilibrium is violated due to the high rate of strain. By independently tuning the relevant linear dimensions and the frequencies of the MEMS and NEMS resonators, we experimentally observe these two different physical mechanisms. All the experimental data, however, can be collapsed using a single dimensionless scaling parameter that combines the linear dimension and the frequency of each resonator. This proposed Knudsen number for oscillatory flows is rooted in a fundamental symmetry principle, namely Galilean invariance. We acknowledge support from US NSF through Grant No. CBET-1604075.

Facile synthesis of mercaptosuccinic acid-capped CdTe/CdS/ZnS core/double shell quantum dots with improved cell viability on different cancer cells and normal cells

NASA Astrophysics Data System (ADS)

Parani, Sundararajan; Bupesh, Giridharan; Manikandan, Elayaperumal; Pandian, Kannaiyan; Oluwafemi, Oluwatobi Samuel

2016-11-01

Water-soluble, mercaptosuccinic acid (MSA)-capped CdTe/CdS/ZnS core/double shell quantum dots (QDs) were prepared by successive growth of CdS and ZnS shells on the as-synthesized CdTe/CdSthin core/shell quantum dots. The formation of core/double shell structured QDs was investigated by ultraviolet-visible (UV-Vis) absorption and photoluminescence (PL) spectroscopy, PL decay studies, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The core/double shell QDs exhibited good photoluminescence quantum yield (PLQY) which is 70% higher than that of the parent core/shell QDs, and they are stable for months. The average particle size of the core/double shell QDs was ˜3 nm as calculated from the transmission electron microscope (TEM) images. The cytotoxicity of the QDs was evaluated on a variety of cancer cells such as HeLa, MCF-7, A549, and normal Vero cells by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) cell viability assay. The results showed that core/double shell QDs were less toxic to the cells when compared to the parent core/shell QDs. MCF-7 cells showed proliferation on incubation with QDs, and this is attributed to the metalloestrogenic activity of cadmium ions released from QDs. The core/double shell CdTe/CdS/ZnS (CSS) QDs were conjugated with transferrin and successfully employed for the biolabeling and fluorescent imaging of HeLa cells. These core/double shell QDs are highly promising fluorescent probe for cancer cell labeling and imaging applications.

Surface-Induced Near-Field Scaling in the Knudsen Layer of a Rarefied Gas

NASA Astrophysics Data System (ADS)

Gazizulin, R. R.; Maillet, O.; Zhou, X.; Cid, A. Maldonado; Bourgeois, O.; Collin, E.

2018-01-01

We report on experiments performed within the Knudsen boundary layer of a low-pressure gas. The noninvasive probe we use is a suspended nanoelectromechanical string, which interacts with He 4 gas at cryogenic temperatures. When the pressure P is decreased, a reduction of the damping force below molecular friction ∝P had been first reported in Phys. Rev. Lett. 113, 136101 (2014), 10.1103/PhysRevLett.113.136101 and never reproduced since. We demonstrate that this effect is independent of geometry, but dependent on temperature. Within the framework of kinetic theory, this reduction is interpreted as a rarefaction phenomenon, carried through the boundary layer by a deviation from the usual Maxwell-Boltzmann equilibrium distribution induced by surface scattering. Adsorbed atoms are shown to play a key role in the process, which explains why room temperature data fail to reproduce it.

Gas Near a Wall: Shortened Mean Free Path, Reduced Viscosity, and the Manifestation of the Knudsen Layer in the Navier-Stokes Solution of a Shear Flow

NASA Astrophysics Data System (ADS)

Abramov, Rafail V.

2018-06-01

For the gas near a solid planar wall, we propose a scaling formula for the mean free path of a molecule as a function of the distance from the wall, under the assumption of a uniform distribution of the incident directions of the molecular free flight. We subsequently impose the same scaling onto the viscosity of the gas near the wall and compute the Navier-Stokes solution of the velocity of a shear flow parallel to the wall. Under the simplifying assumption of constant temperature of the gas, the velocity profile becomes an explicit nonlinear function of the distance from the wall and exhibits a Knudsen boundary layer near the wall. To verify the validity of the obtained formula, we perform the Direct Simulation Monte Carlo computations for the shear flow of argon and nitrogen at normal density and temperature. We find excellent agreement between our velocity approximation and the computed DSMC velocity profiles both within the Knudsen boundary layer and away from it.

Zinc Chromate Induces Chromosome Instability and DNA Double Strand Breaks in Human Lung Cells

PubMed Central

Xie, Hong; Holmes, Amie L.; Young, Jamie L.; Qin, Qin; Joyce, Kellie; Pelsue, Stephen C.; Peng, Cheng; Wise, Sandra S.; Jeevarajan, Antony S.; Wallace, William T.; Hammond, Dianne; Wise, John Pierce

2014-01-01

Hexavalent chromium Cr(VI) is a respiratory toxicant and carcinogen, with solubility playing an important role in its carcinogenic potential. Zinc chromate, a water insoluble or ‘particulate’ Cr(VI) compound, has been shown to be carcinogenic in epidemiology studies and to induce tumors in experimental animals, but its genotoxicity is poorly understood. Our study shows that zinc chromate induced concentration-dependent increases in cytotoxicity, chromosome damage and DNA double strand breaks in human lung cells. In response to zinc chromate-induced breaks, MRE11 expression was increased and ATM and ATR were phosphorylated, indicating that the DNA double strand break repair system was initiated in the cells. In addition, our data show that zinc chromate-induced double strand breaks were only observed in the G2/M phase population, with no significant amount of double strand breaks observed in G1 and S phase cells. These data will aid in understanding the mechanisms of zinc chromate toxicity and carcinogenesis. PMID:19027772

Thermodynamic study of gaseous CsBO2 by Knudsen effusion mass spectrometry

NASA Astrophysics Data System (ADS)

Nakajima, K.; Takai, T.; Furukawa, T.; Osaka, M.

2017-08-01

One of the main chemical forms of cesium in the gas phase during severe light-water reactor accidents is expected to be cesium metaborate, CsBO2, according to thermodynamic equilibrium calculations considering its reaction with boron. However, the accuracy of the thermodynamic data of the gaseous metaborate, CsBO2(g), has been judged as poor. Thus, Knudsen effusion mass spectrometric measurements of CsBO2 were carried out to obtain reliable thermodynamic data. The evaluated values of the standard enthalpy of formation of CsBO2(g), obtained by the 2nd and 3rd-law treatments, are -700.7 ± 10.7 kJ/mol and -697.0 ± 10.6 kJ/mol, respectively, and agree with each other within the experimental errors, which indicates that our data are reliable. Furthermore, it was found that the existing data of the Gibbs energy function and the standard enthalpy of formation agreed well with the values evaluated in this study, which indicates that the existing thermodynamic data are also reliable.

Double-Staining Method for Differentiation of Morphological Changes and Membrane Integrity of Campylobacter coli Cells

PubMed Central

Alonso, Jose L.; Mascellaro, Salvatore; Moreno, Yolanda; Ferrús, María A.; Hernández, Javier

2002-01-01

We developed a double-staining procedure involving NanoOrange dye (Molecular Probes, Eugene, Oreg.) and membrane integrity stains (LIVE/DEAD BacLight kit; Molecular Probes) to show the morphological and membrane integrity changes of Campylobacter coli cells during growth. The conversion from a spiral to a coccoid morphology via intermediary forms and the membrane integrity changes of the C. coli cells can be detected with the double-staining procedure. Our data indicate that young or actively growing cells are mainly spiral shaped (green-stained cells), but older cells undergo a degenerative change to coccoid forms (red-stained cells). Club-shaped transition cell forms were observed with NanoOrange stain. Chlorinated drinking water affected the viability but not the morphology of C. coli cells. PMID:12324366

Construction of Injectable Double-Network Hydrogels for Cell Delivery.

PubMed

Yan, Yan; Li, Mengnan; Yang, Di; Wang, Qian; Liang, Fuxin; Qu, Xiaozhong; Qiu, Dong; Yang, Zhenzhong

2017-07-10

Herein we present a unique method of using dynamic cross-links, which are dynamic covalent bonding and ionic interaction, for the construction of injectable double-network (DN) hydrogels, with the objective of cell delivery for cartilage repair. Glycol chitosan and dibenzaldhyde capped poly(ethylene oxide) formed the first network, while calcium alginate formed the second one, and in the resultant DN hydrogel, either of the networks could be selectively removed. The moduli of the DN hydrogel were significantly improved compared to that of the parent single-network hydrogels and were tunable by changing the chemical components. In situ 3D cell encapsulation could be easily performed by mixing cell suspension to the polymer solutions and transferred through a syringe needle before sol-gel transition. Cell proliferation and mediated differentiation of mouse chondrogenic cells were achieved in the DN hydrogel extracellular matrix.

Cortical Double-Opponent Cells in Color Perception: Perceptual Scaling and Chromatic Visual Evoked Potentials.

PubMed

Nunez, Valerie; Shapley, Robert M; Gordon, James

2018-01-01

In the early visual cortex V1, there are currently only two known neural substrates for color perception: single-opponent and double-opponent cells. Our aim was to explore the relative contributions of these neurons to color perception. We measured the perceptual scaling of color saturation for equiluminant color checkerboard patterns (designed to stimulate double-opponent neurons preferentially) and uniformly colored squares (designed to stimulate only single-opponent neurons) at several cone contrasts. The spatially integrative responses of single-opponent neurons would produce the same response magnitude for checkerboards as for uniform squares of the same space-averaged cone contrast. However, perceived saturation of color checkerboards was higher than for the corresponding squares. The perceptual results therefore imply that double-opponent cells are involved in color perception of patterns. We also measured the chromatic visual evoked potential (cVEP) produced by the same stimuli; checkerboard cVEPs were much larger than those for corresponding squares, implying that double-opponent cells also contribute to the cVEP response. The total Fourier power of the cVEP grew sublinearly with cone contrast. However, the 6-Hz Fourier component's power grew linearly with contrast-like saturation perception. This may also indicate that cortical coding of color depends on response dynamics.

Cortical Double-Opponent Cells in Color Perception: Perceptual Scaling and Chromatic Visual Evoked Potentials

PubMed Central

Shapley, Robert M.; Gordon, James

2018-01-01

In the early visual cortex V1, there are currently only two known neural substrates for color perception: single-opponent and double-opponent cells. Our aim was to explore the relative contributions of these neurons to color perception. We measured the perceptual scaling of color saturation for equiluminant color checkerboard patterns (designed to stimulate double-opponent neurons preferentially) and uniformly colored squares (designed to stimulate only single-opponent neurons) at several cone contrasts. The spatially integrative responses of single-opponent neurons would produce the same response magnitude for checkerboards as for uniform squares of the same space-averaged cone contrast. However, perceived saturation of color checkerboards was higher than for the corresponding squares. The perceptual results therefore imply that double-opponent cells are involved in color perception of patterns. We also measured the chromatic visual evoked potential (cVEP) produced by the same stimuli; checkerboard cVEPs were much larger than those for corresponding squares, implying that double-opponent cells also contribute to the cVEP response. The total Fourier power of the cVEP grew sublinearly with cone contrast. However, the 6-Hz Fourier component’s power grew linearly with contrast-like saturation perception. This may also indicate that cortical coding of color depends on response dynamics. PMID:29375753

Slip Correction Measurements of Certified PSL Nanoparticles Using a Nanometer Differential Mobility Analyzer (Nano-DMA) for Knudsen Number From 0.5 to 83

PubMed Central

Kim, Jung Hyeun; Mulholland, George W.; Kukuck, Scott R.; Pui, David Y. H.

2005-01-01

The slip correction factor has been investigated at reduced pressures and high Knudsen number using polystyrene latex (PSL) particles. Nano-differential mobility analyzers (NDMA) were used in determining the slip correction factor by measuring the electrical mobility of 100.7 nm, 269 nm, and 19.90 nm particles as a function of pressure. The aerosol was generated via electrospray to avoid multiplets for the 19.90 nm particles and to reduce the contaminant residue on the particle surface. System pressure was varied down to 8.27 kPa, enabling slip correction measurements for Knudsen numbers as large as 83. A condensation particle counter was modified for low pressure application. The slip correction factor obtained for the three particle sizes is fitted well by the equation: C = 1 + Kn (α + β exp(−γ/Kn)), with α = 1.165, β = 0.483, and γ = 0.997. The first quantitative uncertainty analysis for slip correction measurements was carried out. The expanded relative uncertainty (95 % confidence interval) in measuring slip correction factor was about 2 % for the 100.7 nm SRM particles, about 3 % for the 19.90 nm PSL particles, and about 2.5 % for the 269 nm SRM particles. The major sources of uncertainty are the diameter of particles, the geometric constant associated with NDMA, and the voltage. PMID:27308102

Double Aneuploidy Detected by Cell-Free DNA Testing and Confirmed by Fetal Tissue Analysis.

PubMed

Echague, Charlene G; Petersen, Scott M

2016-06-01

Double aneuploidies account for 0.21-2.8% of spontaneous abortions resulting from chromosomal abnormalities. Rarely, cell-free DNA testing detects multiple aneuploidies; however, to discern among maternal, placental, and fetal origin, further evaluation is required. A 49-year-old woman, gravida 5 para 0, underwent cell-free DNA testing at 11 4/7 weeks of gestation, which revealed a fetus that was high risk for trisomies 18 and 21. On ultrasonography at 14 weeks of gestation, she was diagnosed with a missed abortion and underwent surgical management. Fetal and placental tissues were sent for analysis and were positive for trisomies 18 and 21, confirming the results of cell-free DNA testing. Our case highlights the ability of cell-free DNA testing to recognize a double aneuploidy confirmed by fetal tissue analysis.

Double-hit lymphomas constitute a highly aggressive subgroup in diffuse large B-cell lymphomas in the era of rituximab.

PubMed

Kobayashi, Tsutomu; Tsutsumi, Yasuhiko; Sakamoto, Natsumi; Nagoshi, Hisao; Yamamoto-Sugitani, Mio; Shimura, Yuji; Mizutani, Shinsuke; Matsumoto, Yosuke; Nishida, Kazuhiro; Horiike, Shigeo; Asano, Naoko; Nakamura, Shigeo; Kuroda, Junya; Taniwaki, Masafumi

2012-11-01

The incorporation of rituximab in immunochemotherapy has improved treatment outcomes for diffuse large B-cell lymphoma, but the prognosis for some diffuse large B-cell lymphomas remains dismal. Identification of adverse prognostic subgroups is essential for the choice of appropriate therapeutic strategy. We retrospectively investigated the impact of so-called 'double-hit' cytogenetic abnormalities, i.e. cytogenetic abnormalities involving c-MYC co-existing with other poor prognostic cytogenetic abnormalities involving BCL2, BCL6 or BACH2, on treatment outcomes for 93 consecutive diffuse large B-cell lymphoma patients. According to the revised international prognostic index, no patients were cytogenetically diagnosed with double-hit lymphomas in the 'very good' risk group or in the 'good' risk group, while 5 of 33 patients had double-hit lymphomas in the 'poor' risk group. All the double-hit lymphoma patients possessed both nodal and extranodal involvement. The overall complete response rate was 89.3%, overall survival 87.1% and progression-free survival 75.8% over 2 years (median observation period: 644 days). The complete response rates were 93.2% for the non-double-hit lymphoma patients and 40.0% for the double-hit lymphoma patients. Significantly longer progression-free survival and overall survival were observed for the 'very good' and the 'good' risk patients than for the 'poor' risk patients. Moreover, the progression-free survival of double-hit lymphoma was significantly shorter than that of the non-double-hit lymphoma 'poor' risk patients (P = 0.016). In addition, the overall survival of the double-hit lymphoma patients also tended to be shorter than that of the non-double-hit lymphoma 'poor' risk group. The diagnosis of double-hit lymphoma can help discriminate a subgroup of highly aggressive diffuse large B-cell lymphomas and indicate the need for the development of novel therapeutic strategies for double-hit lymphoma.

CD22 x Siglec-G double-deficient mice have massively increased B1 cell numbers and develop systemic autoimmunity.

PubMed

Jellusova, Julia; Wellmann, Ute; Amann, Kerstin; Winkler, Thomas H; Nitschke, Lars

2010-04-01

CD22 and Siglec-G are inhibitory coreceptors for BCR-mediated signaling. Although CD22-deficient mice show increased calcium signaling in their conventional B2 cells and a quite normal B cell maturation, Siglec-G-deficient mice have increased calcium mobilization just in B1 cells and show a large expansion of the B1 cell population. Neither CD22-deficient, nor Siglec-G-deficient mice on a pure C57BL/6 or BALB/c background, respectively, develop autoimmunity. Using Siglec-G x CD22 double-deficient mice, we addressed whether Siglec-G and CD22 have redundant functions. Siglec-G x CD22 double-deficient mice show elevated calcium responses in both B1 cells and B2 cells, increased serum IgM levels and an enlarged population of B1 cells. The enlargement of B1 cell numbers is even higher than in Siglecg(-/-) mice. This expansion seems to happen at the expense of B2 cells, which are reduced in absolute cell numbers, but show an activated phenotype. Furthermore, Siglec-G x CD22 double-deficient mice show a diminished immune response to both thymus-dependent and thymus-independent type II Ags. In contrast, B cells from Siglec-G x CD22 double-deficient mice exhibit a hyperproliferative response to stimulation with several TLR ligands. Aged Siglec-G x CD22 double-deficient mice spontaneously develop anti-DNA and antinuclear autoantibodies. These resulted in a moderate form of immune complex glomerulonephritis. These results show that Siglec-G and CD22 have partly compensatory functions and together are crucial in maintaining the B cell tolerance.

Mouse embryonic stem cells, but not somatic cells, predominantly use homologous recombination to repair double-strand DNA breaks.

PubMed

Tichy, Elisia D; Pillai, Resmi; Deng, Li; Liang, Li; Tischfield, Jay; Schwemberger, Sandy J; Babcock, George F; Stambrook, Peter J

2010-11-01

Embryonic stem (ES) cells give rise to all cell types of an organism. Since mutations at this embryonic stage would affect all cells and be detrimental to the overall health of an organism, robust mechanisms must exist to ensure that genomic integrity is maintained. To test this proposition, we compared the capacity of murine ES cells to repair DNA double-strand breaks with that of differentiated cells. Of the 2 major pathways that repair double-strand breaks, error-prone nonhomologous end joining (NHEJ) predominated in mouse embryonic fibroblasts, whereas the high fidelity homologous recombinational repair (HRR) predominated in ES cells. Microhomology-mediated end joining, an emerging repair pathway, persisted at low levels in all cell types examined. The levels of proteins involved in HRR and microhomology-mediated end joining were highly elevated in ES cells compared with mouse embryonic fibroblasts, whereas those for NHEJ were quite variable, with DNA Ligase IV expression low in ES cells. The half-life of DNA Ligase IV protein was also low in ES cells. Attempts to increase the abundance of DNA Ligase IV protein by overexpression or inhibition of its degradation, and thereby elevate NHEJ in ES cells, were unsuccessful. When ES cells were induced to differentiate, however, the level of DNA Ligase IV protein increased, as did the capacity to repair by NHEJ. The data suggest that preferential use of HRR rather than NHEJ may lend ES cells an additional layer of genomic protection and that the limited levels of DNA Ligase IV may account for the low level of NHEJ activity.

Influence of the charge double layer on solid oxide fuel cell stack behavior

NASA Astrophysics Data System (ADS)

Whiston, Michael M.; Bilec, Melissa M.; Schaefer, Laura A.

2015-10-01

While the charge double layer effect has traditionally been characterized as a millisecond phenomenon, longer timescales may be possible under certain operating conditions. This study simulates the dynamic response of a previously developed solid oxide fuel cell (SOFC) stack model that incorporates the charge double layer via an equivalent circuit. The model is simulated under step load changes. Baseline conditions are first defined, followed by consideration of minor and major deviations from the baseline case. This study also investigates the behavior of the SOFC stack with a relatively large double layer capacitance value, as well as operation of the SOFC stack under proportional-integral (PI) control. Results indicate that the presence of the charge double layer influences the SOFC stack's settling time significantly under the following conditions: (i) activation and concentration polarizations are significantly increased, or (ii) a large value of the double layer capacitance is assumed. Under normal (baseline) operation, on the other hand, the charge double layer effect diminishes within milliseconds, as expected. It seems reasonable, then, to neglect the charge double layer under normal operation. However, careful consideration should be given to potential variations in operation or material properties that may give rise to longer electrochemical settling times.

Lack of clinical AIDS in SIV-infected sooty mangabeys with significant CD4+ T cell loss is associated with double-negative T cells.

PubMed

Milush, Jeffrey M; Mir, Kiran D; Sundaravaradan, Vasudha; Gordon, Shari N; Engram, Jessica; Cano, Christopher A; Reeves, Jacqueline D; Anton, Elizabeth; O'Neill, Eduardo; Butler, Eboneé; Hancock, Kathy; Cole, Kelly S; Brenchley, Jason M; Else, James G; Silvestri, Guido; Sodora, Donald L

2011-03-01

SIV infection of natural host species such as sooty mangabeys results in high viral replication without clinical signs of simian AIDS. Studying such infections is useful for identifying immunologic parameters that lead to AIDS in HIV-infected patients. Here we have demonstrated that acute, SIV-induced CD4(+) T cell depletion in sooty mangabeys does not result in immune dysfunction and progression to simian AIDS and that a population of CD3(+)CD4(-)CD8(-) T cells (double-negative T cells) partially compensates for CD4(+) T cell function in these animals. Passaging plasma from an SIV-infected sooty mangabey with very few CD4(+) T cells to SIV-negative animals resulted in rapid loss of CD4(+) T cells. Nonetheless, all sooty mangabeys generated SIV-specific antibody and T cell responses and maintained normal levels of plasma lipopolysaccharide. Moreover, all CD4-low sooty mangabeys elicited a de novo immune response following influenza vaccination. Such preserved immune responses as well as the low levels of immune activation observed in these animals were associated with the presence of double-negative T cells capable of producing Th1, Th2, and Th17 cytokines. These studies indicate that SIV-infected sooty mangabeys do not appear to rely entirely on CD4(+) T cells to maintain immunity and identify double-negative T cells as a potential subset of cells capable of performing CD4(+) T cell-like helper functions upon SIV-induced CD4(+) T cell depletion in this species.

"Double-Cable" Conjugated Polymers with Linear Backbone toward High Quantum Efficiencies in Single-Component Polymer Solar Cells.

PubMed

Feng, Guitao; Li, Junyu; Colberts, Fallon J M; Li, Mengmeng; Zhang, Jianqi; Yang, Fan; Jin, Yingzhi; Zhang, Fengling; Janssen, René A J; Li, Cheng; Li, Weiwei

2017-12-27

A series of "double-cable" conjugated polymers were developed for application in efficient single-component polymer solar cells, in which high quantum efficiencies could be achieved due to the optimized nanophase separation between donor and acceptor parts. The new double-cable polymers contain electron-donating poly(benzodithiophene) (BDT) as linear conjugated backbone for hole transport and pendant electron-deficient perylene bisimide (PBI) units for electron transport, connected via a dodecyl linker. Sulfur and fluorine substituents were introduced to tune the energy levels and crystallinity of the conjugated polymers. The double-cable polymers adopt a "face-on" orientation in which the conjugated BDT backbone and the pendant PBI units have a preferential π-π stacking direction perpendicular to the substrate, favorable for interchain charge transport normal to the plane. The linear conjugated backbone acts as a scaffold for the crystallization of the PBI groups, to provide a double-cable nanophase separation of donor and acceptor phases. The optimized nanophase separation enables efficient exciton dissociation as well as charge transport as evidenced from the high-up to 80%-internal quantum efficiency for photon-to-electron conversion. In single-component organic solar cells, the double-cable polymers provide power conversion efficiency up to 4.18%. This is one of the highest performances in single-component organic solar cells. The nanophase-separated design can likely be used to achieve high-performance single-component organic solar cells.

Lack of clinical AIDS in SIV-infected sooty mangabeys with significant CD4+ T cell loss is associated with double-negative T cells

PubMed Central

Milush, Jeffrey M.; Mir, Kiran D.; Sundaravaradan, Vasudha; Gordon, Shari N.; Engram, Jessica; Cano, Christopher A.; Reeves, Jacqueline D.; Anton, Elizabeth; O’Neill, Eduardo; Butler, Eboneé; Hancock, Kathy; Cole, Kelly S.; Brenchley, Jason M.; Else, James G.; Silvestri, Guido; Sodora, Donald L.

2011-01-01

SIV infection of natural host species such as sooty mangabeys results in high viral replication without clinical signs of simian AIDS. Studying such infections is useful for identifying immunologic parameters that lead to AIDS in HIV-infected patients. Here we have demonstrated that acute, SIV-induced CD4+ T cell depletion in sooty mangabeys does not result in immune dysfunction and progression to simian AIDS and that a population of CD3+CD4–CD8– T cells (double-negative T cells) partially compensates for CD4+ T cell function in these animals. Passaging plasma from an SIV-infected sooty mangabey with very few CD4+ T cells to SIV-negative animals resulted in rapid loss of CD4+ T cells. Nonetheless, all sooty mangabeys generated SIV-specific antibody and T cell responses and maintained normal levels of plasma lipopolysaccharide. Moreover, all CD4-low sooty mangabeys elicited a de novo immune response following influenza vaccination. Such preserved immune responses as well as the low levels of immune activation observed in these animals were associated with the presence of double-negative T cells capable of producing Th1, Th2, and Th17 cytokines. These studies indicate that SIV-infected sooty mangabeys do not appear to rely entirely on CD4+ T cells to maintain immunity and identify double-negative T cells as a potential subset of cells capable of performing CD4+ T cell–like helper functions upon SIV-induced CD4+ T cell depletion in this species. PMID:21317533

The scaling of relativistic double-year widths - Poisson-Vlasov solutions and particle-in-cell simulations

NASA Technical Reports Server (NTRS)

Sulkanen, Martin E.; Borovsky, Joseph E.

1992-01-01

The study of relativistic plasma double layers is described through the solution of the one-dimensional, unmagnetized, steady-state Poisson-Vlasov equations and by means of one-dimensional, unmagnetized, particle-in-cell simulations. The thickness vs potential-drop scaling law is extended to relativistic potential drops and relativistic plasma temperatures. The transition in the scaling law for 'strong' double layers suggested by analytical two-beam models by Carlqvist (1982) is confirmed, and causality problems of standard double-layer simulation techniques applied to relativistic plasma systems are discussed.

Expressions for the Evaporation and Condensation Coefficients in the Hertz-Knudsen Relation.

PubMed

Persad, Aaron H; Ward, Charles A

2016-07-27

Although the Hertz-Knudsen (HK) relation is often used to correlate evaporation data, the relation contains two empirical parameters (the evaporation and condensation coefficients) that have inexplicably been found to span 3 orders of magnitude. Explicit expressions for these coefficients have yet to be determined. This review will examine sources of error in the HK relation that have led to the coefficients' scatter. Through an examination of theoretical, experimental, and molecular dynamics simulation studies of evaporation, this review will show that the HK relation is incomplete, since it is missing an important physical concept: the coupling between the vapor and liquid phases during evaporation. The review also examines a modified HK relation, obtained from the quantum-mechanically based statistical rate theory (SRT) expression for the evaporation flux and applying a limit to it in which the thermal energy is dominant. Explicit expressions for the evaporation and condensation coefficients are defined in this limit, with the surprising result that the coefficients are not bounded by unity. An examination is made with 127 reported evaporation experiments of water and of ethanol, leading to a new physical interpretation of the coefficients. The review concludes by showing how seemingly small simplifications, such as assuming thermal equilibrium across the liquid-vapor interface during evaporation, can lead to the erroneous predictions from the HK relation that have been reported in the literature.

Size-dependent cell separation and enrichment using double spiral microchannels

NASA Astrophysics Data System (ADS)

Hu, Guoqing; Liu, Chao; Sun, Jiashu; Jiang, Xingyu

2012-11-01

Much attention has been directed toward microfluidic technologies that can help improve circulating tumor cells (CTCs) separation from the blood sample. In the present work, we develop a double spiral microfluidic platform with one inlet and three outlets that allows for passive, label-free tumor cell enrichment with high throughput and efficiency, inspired by the single spiral cell sorter. The curved channel induces a Dean drag force acting on cells to compete with the inertial lift, resulting in large tumor cells to be focused and deflected into the middle outlet while small hematologic cells are removed from the inner outlet. We continuously isolated and enriched the rare tumor cells (MCF-7 and Hela cells) from diluted whole blood using the same geometry. At a spike ratio of 100 tumor cells per million hematologic cells, 92.28% of blood cells and 96.77% of tumor cells were collected at the inner and middle outlet, respectively, at the throughput of 33.3 million cells per minute. A numerical model is developed to simulate the Dean flows inside the curved geometry and to track the particle/cell trajectories, which is validated against the experimental observations and serves as a theoretical foundation in optimizing the operating conditions.

Communication — Modeling polymer-electrolyte fuel-cell agglomerates with double-trap kinetics

DOE PAGES

Pant, Lalit M.; Weber, Adam Z.

2017-04-14

A new semi-analytical agglomerate model is presented for polymer-electrolyte fuel-cell cathodes. The model uses double-trap kinetics for the oxygen-reduction reaction, which can capture the observed potential-dependent coverage and Tafel-slope changes. An iterative semi-analytical approach is used to obtain reaction rate constants from the double-trap kinetics, oxygen concentration at the agglomerate surface, and overall agglomerate reaction rate. The analytical method can predict reaction rates within 2% of the numerically simulated values for a wide range of oxygen concentrations, overpotentials, and agglomerate sizes, while saving simulation time compared to a fully numerical approach.

Investigation of a redox-sensitive predictive model of mouse embryonic stem cells differentiation using quantitative nuclease protection assays and glutathione redox status

EPA Science Inventory

Investigation of a redox-sensitive predictive model of mouse embryonic stem cell differentiation via quantitative nuclease protection assays and glutathione redox status Chandler KJ,Hansen JM, Knudsen T,and Hunter ES 1. U.S. Environmental Protection Agency, Research Triangl...

Effect of Knudsen thermal force on the performance of low-pressure micro gas sensor

NASA Astrophysics Data System (ADS)

Barzegar Gerdroodbary, M.; Ganji, D. D.; Taeibi-Rahni, M.; Vakilipour, Shidvash

2017-07-01

In this paper, Direct Simulation Monte Carlo (DSMC) simulations were applied to investigate the mechanism of the force generation inside a low-pressure gas sensor. The flow feature and force generation mechanism inside a rectangular enclosure with heat and cold arms as the non-isothermal walls are comprehensively explained. In addition, extensive parametric studies are done to study the effects of physical parameters on the performance and characteristics of this device in different operating conditions. In this research, the Knudsen number is varied from 0.1 to 4.5 (0.5 to 11torr) to reveal all the characteristics of the thermally driven force inside the MEMS sensor. In order to simulate a rarefied gas inside the micro gas detector, Boltzmann equations are applied to obtain high-precision results. The effects of ambient pressure and temperature difference of arms are comprehensively investigated. Our findings show that maximum force increases more than 7 times when the temperature difference of the cold and hot arms is increased from 10 to 100K. In addition, the results demonstrate that the thermal gradient at rarefied pressure induces complex structure, and the mechanism of force generation highly varies at different pressure conditions.

Double-hit or dual expression of MYC and BCL2 in primary cutaneous large B-cell lymphomas.

PubMed

Menguy, Sarah; Frison, Eric; Prochazkova-Carlotti, Martina; Dalle, Stephane; Dereure, Olivier; Boulinguez, Serge; Dalac, Sophie; Machet, Laurent; Ram-Wolff, Caroline; Verneuil, Laurence; Gros, Audrey; Vergier, Béatrice; Beylot-Barry, Marie; Merlio, Jean-Philippe; Pham-Ledard, Anne

2018-03-26

In nodal diffuse large B-cell lymphoma, the search for double-hit with MYC and BCL2 and/or BCL6 rearrangements or for dual expression of BCL2 and MYC defines subgroups of patients with altered prognosis that has not been evaluated in primary cutaneous large B-cell lymphoma. Our objectives were to assess the double-hit and dual expressor status in a cohort of 44 patients with primary cutaneous large B-cell lymphoma according to the histological subtype and to evaluate their prognosis relevance. The 44 cases defined by the presence of more than 80% of large B-cells in the dermis corresponded to 21 primary cutaneous follicle centre lymphoma with large cell morphology and 23 primary cutaneous diffuse large B-cell lymphoma, leg type. Thirty-one cases (70%) expressed BCL2 and 29 (66%) expressed MYC. Dual expressor profile was observed in 25 cases (57%) of either subtypes (n = 6 or n = 19, respectively). Only one primary cutaneous follicle centre lymphoma, large-cell case had a double-hit status (2%). Specific survival was significantly worse in primary cutaneous diffuse large B-cell lymphoma, leg type than in primary cutaneous follicle centre lymphoma, large cell (p = 0.021) and for the dual expressor primary cutaneous large B-cell lymphoma group (p = 0.030). Both overall survival and specific survival were worse for patients belonging to the dual expressor primary cutaneous diffuse large B-cell lymphoma, leg type subgroup (p = 0.001 and p = 0.046, respectively). Expression of either MYC and/or BCL2 negatively impacted overall survival (p = 0.017 and p = 0.018 respectively). As the differential diagnosis between primary cutaneous follicle centre lymphoma, large cell and primary cutaneous diffuse large B-cell lymphoma, leg type has a major impact on prognosis, dual-expression of BCL2 and MYC may represent a new diagnostic criterion for primary cutaneous diffuse large B-cell lymphoma, leg type subtype and further identifies patients with

A novel (ex situ) method to quantify oxygen diffusion coefficient of polymer fuel cells backing and catalyst layers

NASA Astrophysics Data System (ADS)

Baricci, Andrea; Casalegno, Andrea

2016-09-01

Limiting current density of oxygen reduction reaction in polymer electrolyte fuel cells is determined by several mass transport resistances that lower the concentration of oxygen on the catalyst active site. Among them, diffusion across porous media plays a significant role. Despite the extensive experimental activity documented in PEMFC literature, only few efforts have been dedicated to the measurement of the effective transport properties in porous layers. In the present work, a methodology for ex situ measurement of the effective diffusion coefficient and Knudsen radius of porous layers for polymer electrolyte fuel cells (gas diffusion layer, micro porous layer and catalyst layer) is described and applied to high temperature polymer fuel cells State of Art materials. Regression of the measured quantities by means of a quasi 2D physical model is performed to quantify the Knudsen effect, which is reported to account, respectively, for 30% and 50% of the mass transport resistance in micro porous layer and catalyst layer. On the other side, the model reveals that pressure gradient consequent to permeation in porous layers of high temperature polymer fuel cells has a negligible effect on oxygen concentration in relevant operating conditions.

Modeling of single event transients with dual double-exponential current sources: Implications for logic cell characterization

DOE PAGES

Black, Dolores Archuleta; Robinson, William H.; Wilcox, Ian Zachary; ...

2015-08-07

Single event effects (SEE) are a reliability concern for modern microelectronics. Bit corruptions can be caused by single event upsets (SEUs) in the storage cells or by sampling single event transients (SETs) from a logic path. Likewise, an accurate prediction of soft error susceptibility from SETs requires good models to convert collected charge into compact descriptions of the current injection process. This paper describes a simple, yet effective, method to model the current waveform resulting from a charge collection event for SET circuit simulations. The model uses two double-exponential current sources in parallel, and the results illustrate why a conventionalmore » model based on one double-exponential source can be incomplete. Furthermore, a small set of logic cells with varying input conditions, drive strength, and output loading are simulated to extract the parameters for the dual double-exponential current sources. As a result, the parameters are based upon both the node capacitance and the restoring current (i.e., drive strength) of the logic cell.« less

Restriction Endonucleases from Invasive Neisseria gonorrhoeae Cause Double-Strand Breaks and Distort Mitosis in Epithelial Cells during Infection

PubMed Central

Weyler, Linda; Engelbrecht, Mattias; Mata Forsberg, Manuel; Brehwens, Karl; Vare, Daniel; Vielfort, Katarina; Wojcik, Andrzej; Aro, Helena

2014-01-01

The host epithelium is both a barrier against, and the target for microbial infections. Maintaining regulated cell growth ensures an intact protective layer towards microbial-induced cellular damage. Neisseria gonorrhoeae infections disrupt host cell cycle regulation machinery and the infection causes DNA double strand breaks that delay progression through the G2/M phase. We show that intracellular gonococci upregulate and release restriction endonucleases that enter the nucleus and damage human chromosomal DNA. Bacterial lysates containing restriction endonucleases were able to fragment genomic DNA as detected by PFGE. Lysates were also microinjected into the cytoplasm of cells in interphase and after 20 h, DNA double strand breaks were identified by 53BP1 staining. In addition, by using live-cell microscopy and NHS-ester stained live gonococci we visualized the subcellular location of the bacteria upon mitosis. Infected cells show dysregulation of the spindle assembly checkpoint proteins MAD1 and MAD2, impaired and prolonged M-phase, nuclear swelling, micronuclei formation and chromosomal instability. These data highlight basic molecular functions of how gonococcal infections affect host cell cycle regulation, cause DNA double strand breaks and predispose cellular malignancies. PMID:25460012

Restriction endonucleases from invasive Neisseria gonorrhoeae cause double-strand breaks and distort mitosis in epithelial cells during infection.

PubMed

Weyler, Linda; Engelbrecht, Mattias; Mata Forsberg, Manuel; Brehwens, Karl; Vare, Daniel; Vielfort, Katarina; Wojcik, Andrzej; Aro, Helena

2014-01-01

The host epithelium is both a barrier against, and the target for microbial infections. Maintaining regulated cell growth ensures an intact protective layer towards microbial-induced cellular damage. Neisseria gonorrhoeae infections disrupt host cell cycle regulation machinery and the infection causes DNA double strand breaks that delay progression through the G2/M phase. We show that intracellular gonococci upregulate and release restriction endonucleases that enter the nucleus and damage human chromosomal DNA. Bacterial lysates containing restriction endonucleases were able to fragment genomic DNA as detected by PFGE. Lysates were also microinjected into the cytoplasm of cells in interphase and after 20 h, DNA double strand breaks were identified by 53BP1 staining. In addition, by using live-cell microscopy and NHS-ester stained live gonococci we visualized the subcellular location of the bacteria upon mitosis. Infected cells show dysregulation of the spindle assembly checkpoint proteins MAD1 and MAD2, impaired and prolonged M-phase, nuclear swelling, micronuclei formation and chromosomal instability. These data highlight basic molecular functions of how gonococcal infections affect host cell cycle regulation, cause DNA double strand breaks and predispose cellular malignancies.

Cell force mapping using a double-sided micropillar array based on the moiré fringe method

NASA Astrophysics Data System (ADS)

Zhang, F.; Anderson, S.; Zheng, X.; Roberts, E.; Qiu, Y.; Liao, R.; Zhang, X.

2014-07-01

The mapping of traction forces is crucial to understanding the means by which cells regulate their behavior and physiological function to adapt to and communicate with their local microenvironment. To this end, polymeric micropillar arrays have been used for measuring cell traction force. However, the small scale of the micropillar deflections induced by cell traction forces results in highly inefficient force analyses using conventional optical approaches; in many cases, cell forces may be below the limits of detection achieved using conventional microscopy. To address these limitations, the moiré phenomenon has been leveraged as a visualization tool for cell force mapping due to its inherent magnification effect and capacity for whole-field force measurements. This Letter reports an optomechanical cell force sensor, namely, a double-sided micropillar array (DMPA) made of poly(dimethylsiloxane), on which one side is employed to support cultured living cells while the opposing side serves as a reference pattern for generating moiré patterns. The distance between the two sides, which is a crucial parameter influencing moiré pattern contrast, is predetermined during fabrication using theoretical calculations based on the Talbot effect that aim to optimize contrast. Herein, double-sided micropillar arrays were validated by mapping mouse embryo fibroblast contraction forces and the resulting force maps compared to conventional microscopy image analyses as the reference standard. The DMPA-based approach precludes the requirement for aligning two independent periodic substrates, improves moiré contrast, and enables efficient moiré pattern generation. Furthermore, the double-sided structure readily allows for the integration of moiré-based cell force mapping into microfabricated cell culture environments or lab-on-a-chip devices.

Dihydroartemisinin induces autophagy-dependent death in human tongue squamous cell carcinoma cells through DNA double-strand break-mediated oxidative stress

PubMed Central

Li, Xiaoming; Bai, Jing; Li, Jianchun; Li, Shenghao; Wang, Zeming; Zhou, Mingrui

2017-01-01

Dihydroartemisinin is an effective antimalarial agent with multiple biological activities. In the present investigation, we elucidated its therapeutic potential and working mechanism on human tongue squamous cell carcinoma (TSCC). It was demonstrated that dihydroartemisinin could significantly inhibit cell growth in a dose- and time-dependent manner by the Cell Counting Kit-8 and colony formation assay in vitro. Meanwhile, autophagy was promoted in the Cal-27 cells treated by dihydroartemisinin, evidenced by increased LC3B-II level, increased autophagosome formation, and increased Beclin-1 level compared to dihydroartemisinin-untreated cells. Importantly, dihydroartemisinin caused DNA double-strand break with simultaneously increased γH2AX foci and oxidative stress; this inhibited the nuclear localization of phosphorylated signal transducer and activator of transcription 3 (p-STAT3), finally leading to autophagic cell death. Furthermore, the antitumor effect of dihydroartemisinin-monotherapy was confirmed with a mouse xenograft model, and no kidney injury associated with toxic effect was observed after intraperitoneal injection with dihydroartemisinin for 3 weeks in vivo. In the present study, it was revealed that dihydroartemisinin-induced DNA double-strand break promoted oxidative stress, which decreased p-STAT3 (Tyr705) nuclear localization, and successively increased autophagic cell death in the Cal-27 cells. Thus, dihydroartemisinin alone may represent an effective and safe therapeutic agent for human TSCC. PMID:28526807

The Dawn of Lead‐Free Perovskite Solar Cell: Highly Stable Double Perovskite Cs2AgBiBr6 Film

PubMed Central

Wu, Cuncun; Zhang, Qiaohui; Liu, Yang; Luo, Wei; Guo, Xuan; Huang, Ziru; Ting, Hungkit; Sun, Weihai; Zhong, Xinrui; Wei, Shiyuan

2017-01-01

Abstract Recently, lead‐free double perovskites have emerged as a promising environmentally friendly photovoltaic material for their intrinsic thermodynamic stability, appropriate bandgaps, small carrier effective masses, and low exciton binding energies. However, currently no solar cell based on these double perovskites has been reported, due to the challenge in film processing. Herein, a first lead‐free double perovskite planar heterojunction solar cell with a high quality Cs2AgBiBr6 film, fabricated by low‐pressure assisted solution processing under ambient conditions, is reported. The device presents a best power conversion efficiency of 1.44%. The preliminary efficiency and the high stability under ambient condition without encapsulation, together with the high film quality with simple processing, demonstrate promise for lead‐free perovskite solar cells. PMID:29593974

The Dawn of Lead-Free Perovskite Solar Cell: Highly Stable Double Perovskite Cs2AgBiBr6 Film.

PubMed

Wu, Cuncun; Zhang, Qiaohui; Liu, Yang; Luo, Wei; Guo, Xuan; Huang, Ziru; Ting, Hungkit; Sun, Weihai; Zhong, Xinrui; Wei, Shiyuan; Wang, Shufeng; Chen, Zhijian; Xiao, Lixin

2018-03-01

Recently, lead-free double perovskites have emerged as a promising environmentally friendly photovoltaic material for their intrinsic thermodynamic stability, appropriate bandgaps, small carrier effective masses, and low exciton binding energies. However, currently no solar cell based on these double perovskites has been reported, due to the challenge in film processing. Herein, a first lead-free double perovskite planar heterojunction solar cell with a high quality Cs 2 AgBiBr 6 film, fabricated by low-pressure assisted solution processing under ambient conditions, is reported. The device presents a best power conversion efficiency of 1.44%. The preliminary efficiency and the high stability under ambient condition without encapsulation, together with the high film quality with simple processing, demonstrate promise for lead-free perovskite solar cells.

DSMC Simulation and Experimental Validation of Shock Interaction in Hypersonic Low Density Flow

PubMed Central

2014-01-01

Direct simulation Monte Carlo (DSMC) of shock interaction in hypersonic low density flow is developed. Three collision molecular models, including hard sphere (HS), variable hard sphere (VHS), and variable soft sphere (VSS), are employed in the DSMC study. The simulations of double-cone and Edney's type IV hypersonic shock interactions in low density flow are performed. Comparisons between DSMC and experimental data are conducted. Investigation of the double-cone hypersonic flow shows that three collision molecular models can predict the trend of pressure coefficient and the Stanton number. HS model shows the best agreement between DSMC simulation and experiment among three collision molecular models. Also, it shows that the agreement between DSMC and experiment is generally good for HS and VHS models in Edney's type IV shock interaction. However, it fails in the VSS model. Both double-cone and Edney's type IV shock interaction simulations show that the DSMC errors depend on the Knudsen number and the models employed for intermolecular interaction. With the increase in the Knudsen number, the DSMC error is decreased. The error is the smallest in HS compared with those in the VHS and VSS models. When the Knudsen number is in the level of 10−4, the DSMC errors, for pressure coefficient, the Stanton number, and the scale of interaction region, are controlled within 10%. PMID:24672360

On the Origin of the Double-cell Meridional Circulation in the Solar Convection Zone

NASA Astrophysics Data System (ADS)

Pipin, V. V.; Kosovichev, A. G.

2018-02-01

Recent advances in helioseismology, numerical simulations and mean-field theory of solar differential rotation have shown that the meridional circulation pattern may consist of two or more cells in each hemisphere of the convection zone. According to the mean-field theory the double-cell circulation pattern can result from the sign inversion of a nondiffusive part of the radial angular momentum transport (the so-called Λ-effect) in the lower part of the solar convection zone. Here, we show that this phenomenon can result from the radial inhomogeneity of the Coriolis number, which depends on the convective turnover time. We demonstrate that if this effect is taken into account then the solar-like differential rotation and the double-cell meridional circulation are both reproduced by the mean-field model. The model is consistent with the distribution of turbulent velocity correlations determined from observations by tracing motions of sunspots and large-scale magnetic fields, indicating that these tracers are rooted just below the shear layer.

Engineering artificial cells by combining HeLa-based cell-free expression and ultra-thin double emulsion template

PubMed Central

Ho, Kwun Yin; Murray, Victoria L.; Liu, Allen P.

2015-01-01

Generation of artificial cells provides the bridge needed to cover the gap between studying the complexity of biological processes in whole cells and studying these same processes in an in vitro reconstituted system. Artificial cells are defined as the encapsulation of biologically active material in a biological or synthetic membrane. Here, we describe a robust and general method to produce artificial cells for the purpose of mimicking one or more behaviors of a cell. A microfluidic double emulsion system is used to encapsulate a mammalian cell free expression system that is able to express membrane proteins into the bilayer or soluble proteins inside the vesicles. The development of a robust platform that allows the assembly of artificial cells is valuable in understanding subcellular functions and emergent behaviors in a more cell-like environment as well as for creating novel signaling pathways to achieve specific cellular behaviors. PMID:25997354

Oncogenic ras-driven cancer cell vesiculation leads to emission of double-stranded DNA capable of interacting with target cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Tae Hoon; Chennakrishnaiah, Shilpa; Audemard, Eric

2014-08-22

Highlights: • Oncogenic H-ras stimulates emission of extracellular vesicles containing double-stranded DNA. • Vesicle-associated extracellular DNA contains mutant N-ras sequences. • Vesicles mediate intercellular transfer of mutant H-ras DNA to normal fibroblasts where it remains for several weeks. • Fibroblasts exposed to vesicles containing H-ras DNA exhibit increased proliferation. - Abstract: Cell free DNA is often regarded as a source of genetic cancer biomarkers, but the related mechanisms of DNA release, composition and biological activity remain unclear. Here we show that rat epithelial cell transformation by the human H-ras oncogene leads to an increase in production of small, exosomal-like extracellularmore » vesicles by viable cancer cells. These EVs contain chromatin-associated double-stranded DNA fragments covering the entire host genome, including full-length H-ras. Oncogenic N-ras and SV40LT sequences were also found in EVs emitted from spontaneous mouse brain tumor cells. Disruption of acidic sphingomyelinase and the p53/Rb pathway did not block emission of EV-related oncogenic DNA. Exposure of non-transformed RAT-1 cells to EVs containing mutant H-ras DNA led to the uptake and retention of this material for an extended (30 days) but transient period of time, and stimulated cell proliferation. Thus, our study suggests that H-ras-mediated transformation stimulates vesicular emission of this histone-bound oncogene, which may interact with non-transformed cells.« less

Demonstration of motionless Knudsen pump based micro-gas chromatography featuring micro-fabricated columns and on-column detectors.

PubMed

Liu, Jing; Gupta, Naveen K; Wise, Kensall D; Gianchandani, Yogesh B; Fan, Xudong

2011-10-21

This paper reports the investigation of a micro-gas chromatography (μGC) system that utilizes an array of miniaturized motionless Knudsen pumps (KPs) as well as microfabricated separation columns and optical detectors. A prototype system was built to achieve a flow rate of 1 mL min(-1) and 0.26 mL min(-1) for helium and dry air, respectively, when they were used as carrier gas. This system was then employed to evaluate GC performance compromises and demonstrate the ability to separate and detect gas mixtures containing analytes of different volatilities and polarities. Furthermore, the use of pressure programming of the KP array was demonstrated to significantly shorten the analysis time while maintaining a high detection resolution. Using this method, we obtained a high resolution detection of 5 alkanes of different volatilities within 5 min. Finally, we successfully detected gas mixtures of various polarities using a tandem-column μGC configuration by installing two on-column optical detectors to obtain complementary chromatograms.

Sol-Gel Deposited Double Layer TiO₂ and Al₂O₃ Anti-Reflection Coating for Silicon Solar Cell.

PubMed

Jung, Jinsu; Jannat, Azmira; Akhtar, M Shaheer; Yang, O-Bong

2018-02-01

In this work, the deposition of double layer ARC on p-type Si solar cells was carried out by simple spin coating using sol-gel derived Al2O3 and TiO2 precursors for the fabrication of crystalline Si solar cells. The first ARC layer was created by freshly prepared sol-gel derived Al2O3 precursor using spin coating technique and then second ARC layer of TiO2 was deposited with sol-gel derived TiO2 precursor, which was finally annealed at 400 °C. The double layer Al2O3/TiO2 ARC on Si wafer exhibited the low average reflectance of 4.74% in the wavelength range of 400 and 1000 nm. The fabricated solar cells based on double TiO2/Al2O3 ARC attained the conversion efficiency of ~13.95% with short circuit current (JSC) of 35.27 mA/cm2, open circuit voltage (VOC) of 593.35 mV and fill factor (FF) of 66.67%. Moreover, the fabricated solar cells presented relatively low series resistance (Rs) as compared to single layer ARCs, resulting in the high VOC and FF.

Preparation and regulating cell adhesion of anion-exchangeable layered double hydroxide micropatterned arrays.

PubMed

Yao, Feng; Hu, Hao; Xu, Sailong; Huo, Ruijie; Zhao, Zhiping; Zhang, Fazhi; Xu, Fujian

2015-02-25

We describe a reliable preparation of MgAl-layered double hydroxide (MgAl-LDH) micropatterned arrays on gold substrate by combining SO3(-)-terminated self-assembly monolayer and photolithography. The synthesis route is readily extended to prepare LDH arrays on the SO3(-)-terminated polymer-bonded glass substrate amenable for cell imaging. The anion-exchangeable MgAl-LDH micropattern can act both as bioadhesive region for selective cell adhesion and as nanocarrier for drug molecules to regulate cell behaviors. Quantitative analysis of cell adhesion shows that selective HepG2 cell adhesion and spreading are promoted by the micropatterned MgAl-LDH, and also suppressed by methotrexate drug released from the LDH interlayer galleries.

Cutaneous double-hit B-cell lymphoma: an aggressive form of B-cell lymphoma with a propensity for cutaneous dissemination.

PubMed

Magro, Cynthia M; Wang, Xuan; Subramaniyam, Shivakumar; Darras, Natasha; Mathew, Susan

2014-04-01

Diffuse large cell B-cell lymphoma of the skin is most commonly represented by diffuse large cell variants of primary cutaneous follicle center cell lymphoma and the leg-type lymphoma. In a minority of cases, the infiltrates are an expression of stage 4 disease of established extracutaneous B-cell lymphoma. We describe 3 patients with an aggressive form of B-cell lymphoma secondarily involving the skin. Two of the patients were in the ninth decade of life, whereas 1 patient was 34 years of age. In the elderly patients, there was an antecedent and/or concurrent history of follicular lymphoma, whereas in the younger patient, the tumor was a de novo presentation of this aggressive form of lymphoma. The elderly patients succumbed to their disease within less than a year from the time of diagnosis, whereas 1 patient is alive but with persistent and progressive disease despite chemotherapeutic intervention. The infiltrates in all 3 cases were diffuse and composed of large malignant hematopoietic cells that exhibited a round nucleus with a finely dispersed chromatin. Phenotypically, the tumor cells were Bcl-2 and CD10 positive, whereas Bcl-6 and Mum-1 showed variable positivity. One case showed combined Mum-1 positivity along with an acute lymphoblastic lymphoma phenotype, including the absence of CD20 expression. In each case, there was a c-MYC and BCL2/IGH rearrangement diagnostic of double-hit lymphoma. In one case, there was an additional BCL6 rearrangement, defining what is in essence triple-hit lymphoma. In conclusion, double-hit lymphoma is an aggressive form of B-cell neoplasia resistant to standard chemotherapy regimens, which in many but not all cases represents tumor progression in the setting of a lower grade B-cell malignancy.

Thermodynamic properties of gaseous cerium molybdates and tungstates studied by Knudsen effusion mass spectrometry.

PubMed

Shugurov, S M; Panin, A I; Lopatin, S I

2018-06-21

CeO 2 -WO 3 and CeO 2 -MoO 3 catalysts have shown excellent performance in the selective reduction of NO x by ammonia (NH 3 -selective catalytic reduction) over a wide temperature range. Strong interaction between CeO 2 and WO 3 or MoO 3 might be the dominant reason for the high activity of these mixed oxides. Studies of ceria-containing gaseous salts involve considerable experimental difficulties, since the transition of such salts to vapor requires high temperatures. To predict the possibility of the existence of gaseous associates formed by cerium and molybdenum (tungsten) oxides it is important to know their thermodynamic characteristics. Until the present investigation, gaseous cerium oxyacid salts were unknown. Knudsen effusion mass spectrometry was used to determine the partial pressures of vapor species and the equilibrium constants of gas-phase reactions, as well as the formation and atomization enthalpies of gaseous cerium molybdates and tungstates. CeO 2 was evaporated from molybdenum and tungsten effusion cells containing gold metal as a pressure standard. A theoretical study of gaseous cerium gaseous molybdates and tungstates was performed by several quantum chemical methods. In the temperature range 2050-2400 K, CeO, CeO 2 , XO 2 , XO 3 , CeWO 3 , CeXO 4 , CeXO 5 (X = Mo, W) and CeMo 2 O 7 were found to be the main vapor species over the CeO 2 - Mo (W) systems. On the basis of the equilibrium constants of the gaseous reactions, the standard formation enthalpies of gaseous CeWO 3 , CeXO 4 , CeXO 5 (X = Mo, W) and CeMo 2 O 7 at 298 K were determined. Energetically favorable structures of gaseous cerium salts were found and vibrational frequencies were evaluated in the harmonic approximation. The thermal stability of gaseous cerium oxyacid salts was confirmed by high-temperature mass spectrometry. Reaction enthalpies of the gaseous cerium molybdates and tungstates from gaseous cerium, molybdenum and tungsten oxides were evaluated theoretically and the

Rb vapor-cell clock demonstration with a frequency-doubled telecom laser.

PubMed

Almat, Nil; Pellaton, Matthieu; Moreno, William; Gruet, Florian; Affolderbach, Christoph; Mileti, Gaetano

2018-06-01

We employ a recently developed laser system, based on a low-noise telecom laser emitting around 1.56 μm, to evaluate its impact on the performance of an Rb vapor-cell clock in a continuous-wave double-resonance scheme. The achieved short-term clock instability below 2.5·10 -13 ·τ -1/2 demonstrates, for the first time, the suitability of a frequency-doubled telecom laser for this specific application. We measure and study quantitatively the impact of laser amplitude and frequency noises and of the ac Stark shift, which limit the clock frequency stability on short timescales. We also report on the detailed noise budgets and demonstrate experimentally that, under certain conditions, the short-term stability of the clock operated with the low-noise telecom laser is improved by a factor of three compared to clock operation using the direct 780-nm laser.

[Killing effects of PWZL plasmid-mediated double suicide gene on human lens epithelium cells].

PubMed

Yan, Xiao-ran; Wu, Hong; Yu, Hai-tao; Wang, Xiu; Zhang, Yu

2008-04-01

To investigate the killing efficiency of PWZL plasmid-mediated herpes simplex virus-thymidine kinase (TK) and E. coli cytosine deaminase (CD) on human lens epithelium cells followed by the treatment of prodrugs. PWZL plasmid was used as a vehicle, to transduce double suicide genes into the human lens epithelium in vitro, then the cells were treated with fluorocytosine (5-FC) and/or ganciclovir (GCV) at different concentrations. The cell growth of the lens epithelium cells was observed by light microscope. MTT analysis was used to estimate the cell survival rate and the bystander effect was analyzed simultaneously. The significance of difference between each group was treated by statistical tests. The CD and TK gene could be joined into PWZL plasmid successfully, and did not have any special effect on normal cells. There was no significant difference in cell viability between CD-TK transfected cells and control cells. Cell viability in cells treated with prodrugs was decreased in a time-dependent manner. At the end of the experiment, cell viability was lowest in GCV 10 mg/L +5-FC 60 mg/L group, GCV 10 mg/L + 5-FC 100 mg/L group and GCV 100 mg/L + 5-FC 100 mg/L group. There were no significant differences between these three groups (X2 = 1.25 , P > 0.01). Analysis of bystander effect indicated that the cell viability in GCV 100 mg/L + 5-FC 100 mg/L group and GCV 10 mg/L +5-FC 60 mg/L group was significantly lower than that in the controls (t = 10.26, 13.16; P < 0.01). PWZL plasmid can transfect the CD and TK genes into lens epithelium cells successfully and efficiently. CD and TK genes can be expressed steadily. Transfection of double suicide gene reduces the dosage of prodrugs required for killing cells. The combination of 5-FC with GCV shows the greatest killing effect and also has the bystander effect.

Development of organic-inorganic double hole-transporting material for high performance perovskite solar cells

NASA Astrophysics Data System (ADS)

Jo, Jea Woong; Seo, Myung-Seok; Jung, Jae Woong; Park, Joon-Suh; Sohn, Byeong-Hyeok; Ko, Min Jae; Son, Hae Jung

2018-02-01

The control of the optoelectronic properties of the interlayers of perovskite solar cells (PSCs) is crucial for achieving high photovoltaic performances. Of the solution-processable interlayer candidates, NiOx is considered one of the best inorganic hole-transporting layer (HTL) materials. However, the power conversion efficiencies (PCEs) of NiOx-based PSCs are limited by the unfavorable contact between perovskite layers and NiOx HTLs, the high density of surface trap sites, and the inefficient charge extraction from perovskite photoactive layers to anodes. Here, we introduce a new organic-inorganic double HTL consisting of a Cu:NiOx thin film passivated by a conjugated polyelectrolyte (PhNa-1T) film. This double HTL has a significantly lower pinhole density and forms better contact with perovskite films, which results in enhanced charge extraction. As a result, the PCEs of PSCs fabricated with the double HTL are impressively improved up to 17.0%, which is more than 25% higher than that of the corresponding PSC with a Cu:NiOx HTL. Moreover, PSCs with the double HTLs exhibit similar stabilities under ambient conditions to devices using inorganic Cu:NiOx. Therefore, this organic-inorganic double HTL is a promising interlayer material for high performance PSCs with high air stability.

Tapered Glass-Fiber Microspike: High-Q Flexural Wave Resonator and Optically Driven Knudsen Pump.

PubMed

Pennetta, Riccardo; Xie, Shangran; Russell, Philip St J

2016-12-30

Appropriately designed optomechanical devices are ideal for making ultra-sensitive measurements. Here we report a fused-silica microspike that supports a flexural resonance with a quality factor greater than 100 000 at room temperature in vacuum. Fashioned by tapering single-mode fiber (SMF), it is designed so that the core-guided optical mode in the SMF evolves adiabatically into the fundamental mode of the air-glass waveguide at the tip. The very narrow mechanical linewidth (20 mHz) makes it possible to measure extremely small changes in resonant frequency. In a vacuum chamber at low pressure, the weak optical absorption of the glass is sufficient to create a temperature gradient along the microspike, which causes it to act as a microscopic Knudsen pump, driving a flow of gas molecules towards the tip where the temperature is highest. The result is a circulating molecular flow within the chamber. Momentum exchange between the vibrating microspike and the flowing molecules causes an additional restoring force that can be measured as a tiny shift in the resonant frequency. The effect is strongest when the mean free path of the gas molecules is comparable with the dimensions of the vacuum chamber. The system offers a novel means of monitoring the behavior of weakly absorbing optomechanical sensors operating in vacuum.

Double-chimera proteins to enhance recruitment of endothelial cells and their progenitor cells.

PubMed

Behjati, M; Kazemi, M; Hashemi, M; Zarkesh-Esfahanai, S H; Bahrami, E; Hashemi-Beni, B; Ahmadi, R

2013-08-20

Enhanced attraction of selective vascular reparative cells is of great importance in order to increase vascular patency after endovascular treatments. We aimed to evaluate efficient attachment of endothelial cells and their progenitors on surfaces coated with mixture of specific antibodies, L-selectin and VE-cadherin, with prohibited platelet attachment. The most efficient conditions for coating of L-selectin-Fc chimera and VE-cadherin-Fc chimera proteins were first determined by protein coating on ELISA plates. The whole processes were repeated on titanium substrates, which are commonly used to coat stents. Endothelial progenitor cells (EPCs) and human umbilical vein endothelial cells (HUVECs) were isolated and characterized by flow cytometry. Cell attachment, growth, proliferation, viability and surface cytotoxicity were evaluated using nuclear staining and MTT assay. Platelet and cell attachment were evaluated using scanning electron microscopy. Optimal concentration of each protein for surface coating was 50 ng/ml. The efficacy of protein coating was both heat and pH independent. Calcium ions had significant impact on simultaneous dual-protein coating (P<0.05). Coating stability data revealed more than one year stability for these coated proteins at 4°C. L-selectin and VE-cadherin (ratio of 50:50) coated surface showed highest EPC and HUVEC attachment, viability and proliferation compared to single protein coated and non-coated titanium surfaces (P<0.05). This double coated surface did not show any cytotoxic effect. Surfaces coated with L-selectin and VE-cadherin are friendly surface for EPC and endothelial cell attachment with less platelet attachment. These desirable factors make the L-selectin and VE-cadherin coated surfaces perfect candidate endovascular device. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Mouse but not human embryonic stem cells are deficient in rejoining of ionizing radiation-induced DNA double-strand breaks.

PubMed

Bañuelos, C A; Banáth, J P; MacPhail, S H; Zhao, J; Eaves, C A; O'Connor, M D; Lansdorp, P M; Olive, P L

2008-09-01

Mouse embryonic stem (mES) cells will give rise to all of the cells of the adult mouse, but they failed to rejoin half of the DNA double-strand breaks (dsb) produced by high doses of ionizing radiation. A deficiency in DNA-PK(cs) appears to be responsible since mES cells expressed <10% of the level of mouse embryo fibroblasts (MEFs) although Ku70/80 protein levels were higher than MEFs. However, the low level of DNA-PK(cs) found in wild-type cells appeared sufficient to allow rejoining of dsb after doses <20Gy even in G1 phase cells. Inhibition of DNA-PK(cs) with wortmannin and NU7026 still sensitized mES cells to radiation confirming the importance of the residual DNA-PK(cs) at low doses. In contrast to wild-type cells, mES cells lacking H2AX, a histone protein involved in the DNA damage response, were radiosensitive but they rejoined double-strand breaks more rapidly. Consistent with more rapid dsb rejoining, H2AX(-/-) mES cells also expressed 6 times more DNA-PK(cs) than wild-type mES cells. Similar results were obtained for ATM(-/-) mES cells. Differentiation of mES cells led to an increase in DNA-PK(cs), an increase in dsb rejoining rate, and a decrease in Ku70/80. Unlike mouse ES, human ES cells were proficient in rejoining of dsb and expressed high levels of DNA-PK(cs). These results confirm the importance of homologous recombination in the accurate repair of double-strand breaks in mES cells, they help explain the chromosome abnormalities associated with deficiencies in H2AX and ATM, and they add to the growing list of differences in the way rodent and human cells deal with DNA damage.

Modified Back Contact Interface of CZTSe Thin Film Solar Cells: Elimination of Double Layer Distribution in Absorber Layer.

PubMed

Zhang, Zhaojing; Yao, Liyong; Zhang, Yi; Ao, Jianping; Bi, Jinlian; Gao, Shoushuai; Gao, Qing; Jeng, Ming-Jer; Sun, Guozhong; Zhou, Zhiqiang; He, Qing; Sun, Yun

2018-02-01

Double layer distribution exists in Cu 2 SnZnSe 4 (CZTSe) thin films prepared by selenizing the metallic precursors, which will degrade the back contact of Mo substrate to absorber layer and thus suppressing the performance of solar cell. In this work, the double-layer distribution of CZTSe film is eliminated entirely and the formation of MoSe 2 interfacial layer is inhibited successfully. CZTSe film is prepared by selenizing the precursor deposited by electrodeposition method under Se and SnSe x mixed atmosphere. It is found that the insufficient reaction between ZnSe and Cu-Sn-Se phases in the bottom of the film is the reason why the double layer distribution of CZTSe film is formed. By increasing Sn content in the metallic precursor, thus making up the loss of Sn because of the decomposition of CZTSe and facilitate the diffusion of liquid Cu 2 Se, the double layer distribution is eliminated entirely. The crystallization of the formed thin film is dense and the grains go through the entire film without voids. And there is no obvious MoSe 2 layer formed between CZTSe and Mo. As a consequence, the series resistance of the solar cell reduces significantly to 0.14 Ω cm 2 and a CZTSe solar cell with efficiency of 7.2% is fabricated.

Co-Introduced Functional CCR2 Potentiates In Vivo Anti-Lung Cancer Functionality Mediated by T Cells Double Gene-Modified to Express WT1-Specific T-Cell Receptor

PubMed Central

Asai, Hiroaki; Fujiwara, Hiroshi; An, Jun; Ochi, Toshiki; Miyazaki, Yukihiro; Nagai, Kozo; Okamoto, Sachiko; Mineno, Junichi; Kuzushima, Kiyotaka; Shiku, Hiroshi; Inoue, Hirofumi; Yasukawa, Masaki

2013-01-01

Background and Purpose Although gene-modification of T cells to express tumor-related antigen-specific T-cell receptor (TCR) or chimeric antigen receptor (CAR) has clinically proved promise, there still remains room to improve the clinical efficacy of re-directed T-cell based antitumor adoptive therapy. In order to achieve more objective clinical responses using ex vivo-expanded tumor-responsive T cells, the infused T cells need to show adequate localized infiltration into the tumor. Methodology/Principal Findings Human lung cancer cells variously express a tumor antigen, Wilms' Tumor gene product 1 (WT1), and an inflammatory chemokine, CCL2. However, CCR2, the relevant receptor for CCL2, is rarely expressed on activated T-lymphocytes. A HLA-A2402+ human lung cancer cell line, LK79, which expresses high amounts of both CCL2 and WT1 mRNA, was employed as a target. Normal CD8+ T cells were retrovirally gene-modified to express both CCR2 and HLA-A*2402-restricted and WT1235–243 nonapeptide-specific TCR as an effector. Anti-tumor functionality mediated by these effector cells against LK79 cells was assessed both in vitro and in vivo. Finally the impact of CCL2 on WT1 epitope-responsive TCR signaling mediated by the effector cells was studied. Introduced CCR2 was functionally validated using gene-modified Jurkat cells and human CD3+ T cells both in vitro and in vivo. Double gene-modified CD3+ T cells successfully demonstrated both CCL2-tropic tumor trafficking and cytocidal reactivity against LK79 cells in vitro and in vivo. CCL2 augmented the WT1 epitope-responsive TCR signaling shown by relevant luciferase production in double gene-modified Jurkat/MA cells to express luciferase and WT1-specific TCR, and CCL2 also dose-dependently augmented WT1 epitope-responsive IFN-γ production and CD107a expression mediated by these double gene-modifiedCD3+ T cells. Conclusion/Significance Introduction of the CCL2/CCR2 axis successfully potentiated in vivo anti-lung cancer

Layered Double Hydroxide Nanotransporter for Molecule Delivery to Intact Plant Cells

PubMed Central

Bao, Wenlong; Wang, Junya; Wang, Qiang; O’Hare, Dermot; Wan, Yinglang

2016-01-01

Here we report a powerful method that facilitates the transport of biologically active materials across the cell wall barrier in plant cells. Positively charged delaminated layered double hydroxide lactate nanosheets (LDH-lactate-NS) with a 0.5‒2 nm thickness and 30‒60 nm diameter exhibit a high adsorptive capacity for negatively charged biomolecules, including fluorescent dyes such as tetramethyl rhodamine isothiocyanate (TRITC), fluorescein isothiocyanate isomer I(FITC) and DNA molecules, forming neutral LDH-nanosheet conjugates. These neutral conjugates can shuttle the bound fluorescent dye into the cytosol of intact plant cell very efficiently. Furthermore, typical inhibitors of endocytosis and low temperature incubation did not prevent LDH-lactate-NS internalization, suggesting that LDH-lactate-NS penetrated the plasma membrane via non-endocytic pathways, which will widen the applicability to a variety of plant cells. Moreover, the absence of unwanted side effects in our cytological studies, and the nuclear localization of ssDNA-FITC suggest that nano-LDHs have potential application as a novel gene carrier to plants. PMID:27221055

Sol-gel-Derived nano-sized double layer anti-reflection coatings (SiO2/TiO2) for low-cost solar cell fabrication.

PubMed

Lee, Seung Jun; Hur, Man Gyu; Yoon, Dae Ho

2013-11-01

We investigate nano-sized double layer anti-reflection coatings (ARCs) using a TiO2 and SiO2 sol-gel solution process for mono-crystalline silicon solar cells. The process can be easily adapted for spraying sol-gel coatings to reduce manufacturing cost. The spray-coated SiO2/TiO2 nano-sized double layer ARCs were deposited on mono-crystalline silicon solar cells, and they showed good optical properties. The spray coating process is a lower-cost fabrication process for large-scale coating than vacuum deposition processes such as PECVD. The measured average optical reflectance (300-1200 nm) was about approximately 8% for SiO2/TiO2 nano-sized double layer ARCs. The electrical parameters of a mono-crystalline silicon solar cell and reflection losses show that the SiO2/TiO2 stacks can improve cell efficiency by 0.2% compared to a non-coated mono-crystalline silicon solar cell. In the results, good correlation between theoretical and experimental data was obtained. We expect that the sol-gel spray-coated mono-crystalline silicon solar cells have high potential for low-cost solar cell fabrication.

Modeling and characterization of double resonant tunneling diodes for application as energy selective contacts in hot carrier solar cells

NASA Astrophysics Data System (ADS)

Jehl, Zacharie; Suchet, Daniel; Julian, Anatole; Bernard, Cyril; Miyashita, Naoya; Gibelli, Francois; Okada, Yoshitaka; Guillemolles, Jean-Francois

2017-02-01

Double resonant tunneling barriers are considered for an application as energy selective contacts in hot carrier solar cells. Experimental symmetric and asymmetric double resonant tunneling barriers are realized by molecular beam epitaxy and characterized by temperature dependent current-voltage measurements. The negative differential resistance signal is enhanced for asymmetric heterostructures, and remains unchanged between low- and room-temperatures. Within Tsu-Esaki description of the tunnel current, this observation can be explained by the voltage dependence of the tunnel transmission amplitude, which presents a resonance under finite bias for asymmetric structures. This effect is notably discussed with respect to series resistance. Different parameters related to the electronic transmission of the structure and the influence of these parameters on the current voltage characteristic are investigated, bringing insights on critical processes to optimize in double resonant tunneling barriers applied to hot carrier solar cells.

Study of vaporization of sodium metaborate by transpiration thermogravimetry and Knudsen effusion mass spectrometry.

PubMed

Narasimhan, T S Lakshmi; Viswanathan, R; Nalini, S

2011-11-17

The vaporization of solid sodium metaborate NaBO(2)(s) was studied by transpiration thermogravimetry (TTG) and Knudsen effusion mass spectrometry (KEMS). The transpiration measurements, performed for the first time on NaBO(2)(s), involved use of argon as the carrier gas for vapor transport and derivation of vapor pressure of NaBO(2)(g) (by assuming it as the sole vapor species) through many flow-dependence runs and temperature-dependence runs in the temperature range 1075-1218 K. The KEMS measurements performed in the temperature range 1060-1185 K confirmed NaBO(2)(g) as the principal vapor species over NaBO(2)(s), in accord with the previously reported KEMS studies. The values of p(NaBO(2)) obtained by both TTG and KEMS are consistent within the uncertainties associated with each method and so are the second- and third-law values of enthalpy of sublimation, the latter aspect consistently missing in all previous vaporization studies. The results of both TTG and KEMS were combined to recommend the following thermodynamic parameters pertinent to the sublimation reaction, NaBO(2)(s) = NaBO(2)(g): Log{p(NaBO(2))/Pa} = -(17056 ± 441)/(T/K) + (14.73 ± 0.35) for the temperature range 1060-1218 K; Δ(r)H°(m)(298.15 K) = (346.3 ± 9.4) kJ·mol(-1); and Δ(r)S°(m)(298.15 K) = (210.2 ± 6.8) J·mol(-1)·K(-1).

Biomimetic collagen I and IV double layer Langmuir-Schaefer films as microenvironment for human pluripotent stem cell derived retinal pigment epithelial cells.

PubMed

Sorkio, Anni E; Vuorimaa-Laukkanen, Elina P; Hakola, Hanna M; Liang, Huamin; Ujula, Tiina A; Valle-Delgado, Juan José; Österberg, Monika; Yliperttula, Marjo L; Skottman, Heli

2015-05-01

The environmental cues received by the cells from synthetic substrates in vitro are very different from those they receive in vivo. In this study, we applied the Langmuir-Schaefer (LS) deposition, a variant of Langmuir-Blodgett technique, to fabricate a biomimetic microenvironment mimicking the structure and organization of native Bruch's membrane for the production of the functional human embryonic stem cell derived retinal pigment epithelial (hESC-RPE) cells. Surface pressure-area isotherms were measured simultaneously with Brewster angle microscopy to investigate the self-assembly of human collagens type I and IV on air-subphase interface. Furthermore, the structure of the prepared collagen LS films was characterized with scanning electron microscopy, atomic force microscopy, surface plasmon resonance measurements and immunofluorescent staining. The integrity of hESC-RPE on double layer LS films was investigated by measuring transepithelial resistance and permeability of small molecular weight substance. Maturation and functionality of hESC-RPE cells on double layer collagen LS films was further assessed by RPE-specific gene and protein expression, growth factor secretion, and phagocytic activity. Here, we demonstrated that the prepared collagen LS films have layered structure with oriented fibers corresponding to architecture of the uppermost layers of Bruch's membrane and result in increased barrier properties and functionality of hESC-RPE cells as compared to the commonly used dip-coated controls. Copyright © 2015 Elsevier Ltd. All rights reserved.

Human Cell Assays for Synthesis-Dependent Strand Annealing and Crossing over During Double-Strand Break Repair.

PubMed

Zapotoczny, Grzegorz; Sekelsky, Jeff

2017-04-03

DNA double-strand breaks (DSBs) are one of the most deleterious types of lesions to the genome. Synthesis-dependent strand annealing (SDSA) is thought to be a major pathway of DSB repair, but direct tests of this model have only been conducted in budding yeast and Drosophila To better understand this pathway, we developed an SDSA assay for use in human cells. Our results support the hypothesis that SDSA is an important DSB repair mechanism in human cells. We used siRNA knockdown to assess the roles of a number of helicases suggested to promote SDSA. None of the helicase knockdowns reduced SDSA, but knocking down BLM or RTEL1 increased SDSA. Molecular analysis of repair products suggests that these helicases may prevent long-tract repair synthesis. Since the major alternative to SDSA (repair involving a double-Holliday junction intermediate) can lead to crossovers, we also developed a fluorescent assay that detects crossovers generated during DSB repair. Together, these assays will be useful in investigating features and mechanisms of SDSA and crossover pathways in human cells. Copyright © 2017 Zapotoczny and Sekelsky.

Human Cell Assays for Synthesis-Dependent Strand Annealing and Crossing over During Double-Strand Break Repair

PubMed Central

Zapotoczny, Grzegorz; Sekelsky, Jeff

2017-01-01

DNA double-strand breaks (DSBs) are one of the most deleterious types of lesions to the genome. Synthesis-dependent strand annealing (SDSA) is thought to be a major pathway of DSB repair, but direct tests of this model have only been conducted in budding yeast and Drosophila. To better understand this pathway, we developed an SDSA assay for use in human cells. Our results support the hypothesis that SDSA is an important DSB repair mechanism in human cells. We used siRNA knockdown to assess the roles of a number of helicases suggested to promote SDSA. None of the helicase knockdowns reduced SDSA, but knocking down BLM or RTEL1 increased SDSA. Molecular analysis of repair products suggests that these helicases may prevent long-tract repair synthesis. Since the major alternative to SDSA (repair involving a double-Holliday junction intermediate) can lead to crossovers, we also developed a fluorescent assay that detects crossovers generated during DSB repair. Together, these assays will be useful in investigating features and mechanisms of SDSA and crossover pathways in human cells. PMID:28179392

Manipulating motions of targeted single cells in solution by an integrated double-ring magnetic tweezers imaging microscope.

PubMed

Wu, Meiling; Yadav, Rajeev; Pal, Nibedita; Lu, H Peter

2017-07-01

Controlling and manipulating living cell motions in solution hold a high promise in developing new biotechnology and biological science. Here, we developed a magnetic tweezers device that employs a combination of two permanent magnets in up-down double-ring configuration axially fitting with a microscopic objective, allowing a picoNewton (pN) bidirectional force and motion control on the sample beyond a single upward pulling direction. The experimental force calibration and magnetic field simulation using finite element method magnetics demonstrate that the designed magnetic tweezers covers a linear-combined pN force with positive-negative polarization changes in a tenability of sub-pN scale, which can be utilized to further achieve motion manipulation by shifting the force balance. We demonstrate an application of the up-down double-ring magnetic tweezers for single cell manipulation, showing that the cells with internalized paramagnetic beads can be selectively picked up and guided in a controlled fine motion.

Manipulating motions of targeted single cells in solution by an integrated double-ring magnetic tweezers imaging microscope

NASA Astrophysics Data System (ADS)

Wu, Meiling; Yadav, Rajeev; Pal, Nibedita; Lu, H. Peter

2017-07-01

Controlling and manipulating living cell motions in solution hold a high promise in developing new biotechnology and biological science. Here, we developed a magnetic tweezers device that employs a combination of two permanent magnets in up-down double-ring configuration axially fitting with a microscopic objective, allowing a picoNewton (pN) bidirectional force and motion control on the sample beyond a single upward pulling direction. The experimental force calibration and magnetic field simulation using finite element method magnetics demonstrate that the designed magnetic tweezers covers a linear-combined pN force with positive-negative polarization changes in a tenability of sub-pN scale, which can be utilized to further achieve motion manipulation by shifting the force balance. We demonstrate an application of the up-down double-ring magnetic tweezers for single cell manipulation, showing that the cells with internalized paramagnetic beads can be selectively picked up and guided in a controlled fine motion.

How I treat double-hit lymphoma.

PubMed

Friedberg, Jonathan W

2017-08-03

The 2016 revision of the World Health Organization (WHO) classification for lymphoma has included a new category of lymphoma, separate from diffuse large B-cell lymphoma, termed high-grade B-cell lymphoma with translocations involving myc and bcl-2 or bcl-6 . These lymphomas, which occur in <10% of cases of diffuse large B-cell lymphoma, have been referred to as double-hit lymphomas (or triple-hit lymphomas if all 3 rearrangements are present). It is important to differentiate these lymphomas from the larger group of double-expressor lymphomas, which have increased expression of MYC and BCL-2 and/or BCL-6 by immunohistochemistry, by using variable cutoff percentages to define positivity. Patients with double-hit lymphomas have a poor prognosis when treated with standard chemoimmunotherapy and have increased risk of central nervous system involvement and progression. Double-hit lymphomas may arise as a consequence of the transformation of the underlying indolent lymphoma. There are no published prospective trials in double-hit lymphoma, however retrospective studies strongly suggest that aggressive induction regimens may confer a superior outcome. In this article, I review my approach to the evaluation and treatment of double-hit lymphoma, with an eye toward future clinical trials incorporating rational targeted agents into the therapeutic armamentarium. © 2017 by The American Society of Hematology.

GEM-loaded magnetic albumin nanospheres modified with cetuximab for simultaneous targeting, magnetic resonance imaging, and double-targeted thermochemotherapy of pancreatic cancer cells.

PubMed

Wang, Ling; An, Yanli; Yuan, Chenyan; Zhang, Hao; Liang, Chen; Ding, Fengan; Gao, Qi; Zhang, Dongsheng

2015-01-01

Targeted delivery is a promising strategy to improve the diagnostic imaging and therapeutic effect of cancers. In this paper, novel cetuximab (C225)-conjugated, gemcitabine (GEM)-containing magnetic albumin nanospheres (C225-GEM/MANs) were fabricated and applied as a theranostic nanocarrier to conduct simultaneous targeting, magnetic resonance imaging (MRI), and double-targeted thermochemotherapy against pancreatic cancer cells. Fe3O4 nanoparticles (NPs) and GEM co-loaded albumin nanospheres (GEM/MANs) were prepared, and then C225 was further conjugated to synthesize C225-GEM/MANs. Their morphology, mean particle size, GEM encapsulation ratio, specific cell-binding ability, and thermal dynamic profiles were characterized. The effects of discriminating different EGFR-expressing pancreatic cancer cells (AsPC-1 and MIA PaCa-2) and monitoring cellular targeting effects were assessed by targeted MRI. Lastly, the antitumor efficiency of double/C225/magnetic-targeted and nontargeted thermochemotherapy was compared with chemotherapy alone using 3-(4, 5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and flow cytometry (FCM) assay. When treated with targeted nanospheres, AsPC-1 cells showed a significantly less intense MRI T2 signal than MIA PaCa-2 cells, while both cells had similar signal strength when incubated with nontargeted nanospheres. T2 signal intensity was significantly lower when magnetic and C225 targeting were combined, rather than used alone. The inhibitory and apoptotic rates of each thermochemotherapy group were significantly higher than those of the chemotherapy-alone groups. Additionally, both MTT and FCM analysis verified that double-targeted thermochemotherapy had the highest targeted killing efficiency among all groups. The C225-GEM/MANs can distinguish various EGFR-expressing live pancreatic cancer cells, monitor diverse cellular targeting effects using targeted MRI imaging, and efficiently mediate double-targeted thermochemotherapy

Knudsen effusion mass spectrometric studies over (USn3+U3Sn7) two-phase region of U-Sn system

NASA Astrophysics Data System (ADS)

Manikandan, P.; Trinadh, V. V.; Bera, Suranjan; Narasimhan, T. S. Lakshmi; Ananthasivan, K.; Joseph, M.; Mudali, U. Kamachi

2017-08-01

Vaporisation studies over (USn3+U3Sn7) ;two-phase; field have been carried out by employing Knudsen effusion mass spectrometry (KEMS) in the temperature range of 1050-1226 K. Sn(g) was the species observed in the mass spectrum of the equilibrium vapour phase over the samples (71.5 at% Sn and 73.0 at% Sn). The partial pressure of Sn(g) was measured as a function of temperature over (USn3+U3Sn7) ;two-phase; field and the p-T relation was derived as log (pSn/Pa) = ((-14580 ± 91)/(T/K)) + (8.82 ± 0.08) (1050-1226 K). The vaporisation reaction 3USn3(s) = U3Sn7(s) + 2Sn(g) was evaluated by second law method. The Gibbs energy of formation of USn3(s) was derived as ΔfGm°(U Sn3 , s , T) (±1.8) = -173.4 + 0.055 T (K) (kJ mol-1) (1050-1226 K). The mass spectrometric studies on this system have been carried out for the first time.

Improved Efficiency of Polymer Solar Cells by means of Coating Hole Transporting Layer as Double Layer Deposition

NASA Astrophysics Data System (ADS)

Chonsut, T.; Kayunkid, N.; Rahong, S.; Rangkasikorn, A.; Wirunchit, S.; Kaewprajak, A.; Kumnorkaew, P.; Nukeaw, J.

2017-09-01

Polymer solar cells is one of the promising technologies that gain tremendous attentions in the field of renewable energy. Optimization of thickness for each layer is an important factor determining the efficiency of the solar cells. In this work, the optimum thickness of Poly(3,4-ethylenedioxythione): poly(styrenesulfonate) (PEDOT:PSS), a famous polymer widely used as hole transporting layer in polymer solar cells, is determined through the analyzing of device’s photovoltaic parameters, e.g. short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF) as well as power conversion efficiency (PCE). The solar cells were prepared with multilayer of ITO/PEDOT:PSS/PCDTBT:PC70BM/TiOx/Al by rapid convective deposition. In such preparation technique, the thickness of the thin film is controlled by the deposition speed. The faster deposition speed is used, the thicker film is obtained. Furthermore, double layer deposition of PEDOT:PSS was introduced as an approach to improve solar cell efficiency. The results obviously reveal that, with the increase of PEDOT:PSS thickness, the increments of Jsc and FF play the important role to improve PCE from 3.21% to 4.03%. Interestingly, using double layer deposition of PEDOT:PSS shows the ability to enhance the performance of the solar cells to 6.12% under simulated AM 1.5G illumination of 100 mW/cm2.

The Process of Developing a Multi-Cell KEMS Instrument

NASA Technical Reports Server (NTRS)

Copland, E. H.; Auping, J. V.; Jacobson, N. S.

2012-01-01

Multi-cell KEMS offers many advantages over single cell instruments in regard to in-situ temperature calibration and studies on high temperature alloys and oxides of interest to NASA. The instrument at NASA Glenn is a 90 deg magnetic sector instrument originally designed for single cell operation. The conversion of this instrument to a multi-cell instrument with restricted collimation is discussed. For restricted collimation, the 'field aperture' is in the copper plate separating the Knudsen Cell region and the ionizer and the 'source aperture' is adjacent to the ionizer box. A computer controlled x-y table allows positioning of one of the three cells into the sampling region. Heating is accomplished via a Ta sheet element and temperature is measured via an automatic pyrometer from the bottom of the cells. The computer control and data system have been custom developed for this instrument and are discussed. Future improvements are also discussed.

Modified Back Contact Interface of CZTSe Thin Film Solar Cells: Elimination of Double Layer Distribution in Absorber Layer

PubMed Central

Zhang, Zhaojing; Yao, Liyong; Bi, Jinlian; Gao, Shoushuai; Gao, Qing; Jeng, Ming‐Jer; Sun, Guozhong; Zhou, Zhiqiang; He, Qing; Sun, Yun

2017-01-01

Abstract Double layer distribution exists in Cu2SnZnSe4 (CZTSe) thin films prepared by selenizing the metallic precursors, which will degrade the back contact of Mo substrate to absorber layer and thus suppressing the performance of solar cell. In this work, the double‐layer distribution of CZTSe film is eliminated entirely and the formation of MoSe2 interfacial layer is inhibited successfully. CZTSe film is prepared by selenizing the precursor deposited by electrodeposition method under Se and SnSex mixed atmosphere. It is found that the insufficient reaction between ZnSe and Cu‐Sn‐Se phases in the bottom of the film is the reason why the double layer distribution of CZTSe film is formed. By increasing Sn content in the metallic precursor, thus making up the loss of Sn because of the decomposition of CZTSe and facilitate the diffusion of liquid Cu2Se, the double layer distribution is eliminated entirely. The crystallization of the formed thin film is dense and the grains go through the entire film without voids. And there is no obvious MoSe2 layer formed between CZTSe and Mo. As a consequence, the series resistance of the solar cell reduces significantly to 0.14 Ω cm2 and a CZTSe solar cell with efficiency of 7.2% is fabricated. PMID:29610727

A microchip electrophoresis-mass spectrometric platform with double cell lysis nano-electrodes for automated single cell analysis.

PubMed

Li, Xiangtang; Zhao, Shulin; Hu, Hankun; Liu, Yi-Ming

2016-06-17

Capillary electrophoresis-based single cell analysis has become an essential approach in researches at the cellular level. However, automation of single cell analysis has been a challenge due to the difficulty to control the number of cells injected and the irreproducibility associated with cell aggregation. Herein we report the development of a new microfluidic platform deploying the double nano-electrode cell lysis technique for automated analysis of single cells with mass spectrometric detection. The proposed microfluidic chip features integration of a cell-sized high voltage zone for quick single cell lysis, a microfluidic channel for electrophoretic separation, and a nanoelectrospray emitter for ionization in MS detection. Built upon this platform, a microchip electrophoresis-mass spectrometric method (MCE-MS) has been developed for automated single cell analysis. In the method, cell introduction, cell lysis, and MCE-MS separation are computer controlled and integrated as a cycle into consecutive assays. Analysis of large numbers of individual PC-12 neuronal cells (both intact and exposed to 25mM KCl) was carried out to determine intracellular levels of dopamine (DA) and glutamic acid (Glu). It was found that DA content in PC-12 cells was higher than Glu content, and both varied from cell to cell. The ratio of intracellular DA to Glu was 4.20±0.8 (n=150). Interestingly, the ratio drastically decreased to 0.38±0.20 (n=150) after the cells are exposed to 25mM KCl for 8min, suggesting the cells released DA promptly and heavily while they released Glu at a much slower pace in response to KCl-induced depolarization. These results indicate that the proposed MCE-MS analytical platform may have a great potential in researches at the cellular level. Copyright © 2016 Elsevier B.V. All rights reserved.

Double strand breaks and cell-cycle arrest induced by the cyanobacterial toxin cylindrospermopsin in HepG2 cells.

PubMed

Alja, Štraser; Filipič, Metka; Novak, Matjaž; Žegura, Bojana

2013-08-21

The newly emerging cyanobacterial cytotoxin cylindrospermopsin (CYN) is increasingly found in surface freshwaters, worldwide. It poses a potential threat to humans after chronic exposure as it was shown to be genotoxic in a range of test systems and is potentially carcinogenic. However, the mechanisms of CYN toxicity and genotoxicity are not well understood. In the present study CYN induced formation of DNA double strand breaks (DSBs), after prolonged exposure (72 h), in human hepatoma cells, HepG2. CYN (0.1-0.5 µg/mL, 24-96 h) induced morphological changes and reduced cell viability in a dose and time dependent manner. No significant increase in lactate dehydrogenase (LDH) leakage could be observed after CYN exposure, indicating that the reduction in cell number was due to decreased cell proliferation and not due to cytotoxicity. This was confirmed by imunocytochemical analysis of the cell-proliferation marker Ki67. Analysis of the cell-cycle using flow-cytometry showed that CYN has an impact on the cell cycle, indicating G0/G1 arrest after 24 h and S-phase arrest after longer exposure (72 and 96 h). Our results provide new evidence that CYN is a direct acting genotoxin, causing DSBs, and these facts need to be considered in the human health risk assessment.

Influence of double- and triple-layer antireflection coatings on the formation of photocurrents in multijunction III–V solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musalinov, S. B.; Anzulevich, A. P.; Bychkov, I. V.

2017-01-15

The results of simulation by the transfer-matrix method of TiO{sub 2}/SiO{sub 2} double-layer and TiO{sub 2}/Si{sub 3}N{sub 4}/SiO{sub 2} triple-layer antireflection coatings for multijunction InGaP/GaAs/Ge heterostructure solar cells are presented. The TiO{sub 2}/SiO{sub 2} double-layer antireflection coating is experimentally developed and optimized. The experimental spectral dependences of the external quantum yield of the InGaP/GaAs/Ge heterostructure solar cell and optical characteristics of antireflection coatings, obtained in the simulation, are used to determine the photogenerated current densities of each subcell in the InGaP/GaAs/Ge solar cell under AM1.5D irradiation conditions (1000 W/m{sup 2}) and for the case of zero reflection loss. It ismore » shown in the simulation that the optimized TiO{sub 2}/Si{sub 3}N{sub 4}/SiO{sub 2} triple-layer antireflection coating provides a 2.3 mA/cm{sup 2} gain in the photocurrent density for the Ge subcell under AM1.5D conditions in comparison with the TiO{sub 2}/SiO{sub 2} double-layer antireflection coating under consideration. This thereby provides an increase in the fill factor of the current–voltage curve and in the output electric power of the multijunction solar cell.« less

Novel Double-Hit Model of Radiation and Hyperoxia-Induced Oxidative Cell Damage Relevant to Space Travel.

PubMed

Pietrofesa, Ralph A; Velalopoulou, Anastasia; Lehman, Stacey L; Arguiri, Evguenia; Solomides, Pantelis; Koch, Cameron J; Mishra, Om P; Koumenis, Constantinos; Goodwin, Thomas J; Christofidou-Solomidou, Melpo

2016-06-16

Spaceflight occasionally requires multiple extravehicular activities (EVA) that potentially subject astronauts to repeated changes in ambient oxygen superimposed on those of space radiation exposure. We thus developed a novel in vitro model system to test lung cell damage following repeated exposure to radiation and hyperoxia. Non-tumorigenic murine alveolar type II epithelial cells (C10) were exposed to >95% O₂ for 8 h only (O₂), 0.25 Gy ionizing γ-radiation (IR) only, or a double-hit combination of both challenges (O₂ + IR) followed by 16 h of normoxia (ambient air containing 21% O₂ and 5% CO₂) (1 cycle = 24 h, 2 cycles = 48 h). Cell survival, DNA damage, apoptosis, and indicators of oxidative stress were evaluated after 1 and 2 cycles of exposure. We observed a significant (p < 0.05) decrease in cell survival across all challenge conditions along with an increase in DNA damage, determined by Comet analysis and H2AX phosphorylation, and apoptosis, determined by Annexin-V staining, relative to cells unexposed to hyperoxia or radiation. DNA damage (GADD45α and cleaved-PARP), apoptotic (cleaved caspase-3 and BAX), and antioxidant (HO-1 and Nqo1) proteins were increased following radiation and hyperoxia exposure after 1 and 2 cycles of exposure. Importantly, exposure to combination challenge O₂ + IR exacerbated cell death and DNA damage compared to individual exposures O₂ or IR alone. Additionally levels of cell cycle proteins phospho-p53 and p21 were significantly increased, while levels of CDK1 and Cyclin B1 were decreased at both time points for all exposure groups. Similarly, proteins involved in cell cycle arrest was more profoundly changed with the combination challenges as compared to each stressor alone. These results correlate with a significant 4- to 6-fold increase in the ratio of cells in G2/G1 after 2 cycles of exposure to hyperoxic conditions. We have characterized a novel in vitro model of double-hit, low-level radiation and hyperoxia

General and Virus-Specific Immune Cell Reconstitution Following Double Cord Blood Transplantation

PubMed Central

Saliba, Rima M.; Rezvani, Katayoun; Leen, Ann; Jorgensen, Jeffrey; Shah, Nina; Hosing, Chitra; Parmar, Simrit; Oran, Betul; Olson, Amanda; Mehta, Rohtesh S.; Chemaly, Roy F.; Saunders, Ila M.; Bollard, Catherine M.; Shpall, Elizabeth J.

2015-01-01

Cord blood transplantation (CBT) is curative for many patients with hematologic malignancies but is associated with delayed immune recovery and an increased risk of viral infections compared to human leukocyte antigen (HLA) matched bone marrow or peripheral blood progenitor cell transplantation. In this study we evaluated the significance of lymphocyte recovery in 125 consecutive patients with hematologic malignancies who underwent double-unit CBT (DUCBT) with an anti-thymocyte globulin-containing regimen at our institution. A subset of 65 patients were prospectively evaluated for recovery of T, natural killer (NK) and B cells and in 46 patients we also examined viral-specific T cell recovery against Adenovirus, Epstein-Barr virus, cytomegalovirus, BK virus, respiratory syncytial virus and Influenza antigen. Our results indicate that in recipients of DUCBT, the day 30 absolute lymphocyte count is highly predictive of non-relapse mortality (NRM) and overall survival (OS). Immune recovery post-DUCBT was characterized by prolonged CD8+ and CD4+ T lymphopenia associated with preferential expansion of B and NK cells. We also observed profound delays in quantitative and functional recovery of viral-specific CD4+ and CD8+ T-cell responses for the first year post-CBT. Taken together, our data support efforts aimed at optimizing viral-specific T cell recovery to improve outcomes post-CBT. PMID:25708219

Clinicopathological and genomic analysis of double-hit follicular lymphoma: comparison with high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements.

PubMed

Miyaoka, Masashi; Kikuti, Yara Y; Carreras, Joaquim; Ikoma, Haruka; Hiraiwa, Shinichiro; Ichiki, Akifumi; Kojima, Minoru; Ando, Kiyoshi; Yokose, Tomoyuki; Sakai, Rika; Hoshikawa, Masahiro; Tomita, Naoto; Miura, Ikuo; Takata, Katsuyoshi; Yoshino, Tadashi; Takizawa, Jun; Bea, Silvia; Campo, Elias; Nakamura, Naoya

2018-02-01

Most high-grade B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements are aggressive B-cell lymphomas. Occasional double-hit follicular lymphomas have been described but the clinicopathological features of these tumors are not well known. To clarify the characteristics of double-hit follicular lymphomas, we analyzed 10 cases of double-hit follicular lymphomas and 15 cases of high-grade B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements for clinicopathological and genome-wide copy-number alterations and copy-neutral loss-of-heterozygosity profiles. For double-hit follicular lymphomas, the median age was 67.5 years (range: 48-82 years). The female/male ratio was 2.3. Eight patients presented with advanced clinical stage. The median follow-up time was 20 months (range: 1-132 months). At the end of the follow-up, 8 patients were alive, 2 patients were dead including 1 patient with diffuse large B-cell lymphoma transformation. Rearrangements of MYC/BCL2, MYC/BCL6, and MYC/BCL2/BCL6 were seen in 8, 1, and 1 cases, respectively. The partner of MYC was IGH in 6 cases. There were no cases of histological grade 1, 4 cases of grade 2, 5 cases of grade 3a, and 1 case of grade 3b. Two cases of grade 3a exhibited immunoblast-like morphology. Immunohistochemistry demonstrated 9 cases with ≥50% MYC-positive cells. There was significant difference in MYC intensity (P=0.00004) and MIB-1 positivity (P=0.001) between double-hit follicular lymphomas and high-grade B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements. The genome profile of double-hit follicular lymphomas was comparable with conventional follicular lymphomas (GSE67385, n=198) with characteristic gains of 2p25.3-p11.1, 7p22.3-q36.3, 12q11-q24.33, and loss of 18q21.32-q23 (P<0.05). In comparison with high-grade B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements, double-hit follicular lymphomas had fewer copy-number alterations and minimal common region of gain at 2p16.1 (70%), locus

Dictyostelium myosin I double mutants exhibit conditional defects in pinocytosis.

PubMed

Novak, K D; Peterson, M D; Reedy, M C; Titus, M A

1995-12-01

The functional relationship between three Dictyostelium myosin Is, myoA, myoB, and myoC, has been examined through the creation of double mutants. Two double mutants, myoA-/B- and myoB-/C-, exhibit similar conditional defects in fluid-phase pinocytosis. Double mutants grown in suspension culture are significantly impaired in their ability to take in nutrients from the medium, whereas they are almost indistinguishable from wild-type and single mutant strains when grown on a surface. The double mutants are also found to internalize gp126, a 116-kD membrane protein, at a slower rate than either the wild-type or single mutant cells. Ultrastructural analysis reveals that both double mutants possess numerous small vesicles, in contrast to the wild-type or myosin I single mutants that exhibit several large, clear vacuoles. The alterations in fluid and membrane internalization in the suspension-grown double mutants, coupled with the altered vesicular profile, suggest that these cells may be compromised during the early stages of pinocytosis, a process that has been proposed to occur via actin-based cytoskeletal rearrangements. Scanning electron microscopy and rhodamine-phalloidin staining indicates that the myosin I double mutants appear to extend a larger number of actin-filled structures, such as filopodia and crowns, than wild-type cells. Rhodamine-phalloidin staining of the F-actin cytoskeleton of these suspension-grown cells also reveals that the double mutant cells are delayed in the rearrangement of cortical actin-rich structures upon adhesion to a substrate. We propose that myoA, myoB, and myoC play roles in controlling F-actin filled membrane projections that are required for pinosome internalization in suspension.

Reduce on the Cost of Photovoltaic Power Generation for Polycrystalline Silicon Solar Cells by Double Printing of Ag/Cu Front Contact Layer

NASA Astrophysics Data System (ADS)

Peng, Zhuoyin; Liu, Zhou; Chen, Jianlin; Liao, Lida; Chen, Jian; Li, Cong; Li, Wei

2018-06-01

With the development of photovoltaic industry, the cost of photovoltaic power generation has become the significant issue. And the metallization process has decided the cost of original materials and photovoltaic efficiency of the solar cells. Nowadays, double printing process has been introduced instead of one-step printing process for front contact of polycrystalline silicon solar cells, which can effectively improve the photovoltaic conversion efficiency of silicon solar cells. Here, the relative cheap Cu paste has replaced the expensive Ag paste to form Ag/Cu composite front contact of silicon solar cells. The photovoltaic performance and the cost of photovoltaic power generation have been investigated. With the optimization on structure and height of Cu finger layer for Ag/Cu composite double-printed front contact, the silicon solar cells have exhibited a photovoltaic conversion efficiency of 18.41%, which has reduced 3.42 cent per Watt for the cost of photovoltaic power generation.

Mixed metal oxides for dye-sensitized solar cell using zinc titanium layered double hydroxide as precursor

NASA Astrophysics Data System (ADS)

Liu, Jianqiang; Qin, Yaowei; Zhang, Liangji; Xiao, Hongdi; Song, Jianye; Liu, Dehe; Leng, Mingzhe; Hou, Wanguo; Du, Na

2013-12-01

Mixed metal oxides (MMO) are always obtained from layered double hydroxide (LDH) by thermal decomposition. In the present work, a zinc titanium LDH with the zinc titanium molar ratio of 4.25 was prepared by urea method and ZnO-based mixed oxides were obtained by calcining at or over 500°C. The MMO was used as electrodes for dye sensitized solar cell (DSSC). The cells constructed by films of prepared composite materials using a N719 as dye were prepared. The efficiency values of these cells are 0.691%, 0.572% and 0.302% with MMO prepared at 500, 600 and 700°C, respectively.

T-cell chronic lymphocytic leukemia in a double yellow-headed Amazon parrot (Amazona ochrocephala oratrix).

PubMed

Osofsky, Anna; Hawkins, Michelle G; Foreman, Oded; Kent, Michael S; Vernau, William; Lowenstine, Linda J

2011-12-01

An adult, male double yellow-headed Amazon parrot (Amazona ochrocephala oratrix) was diagnosed with chronic lymphocytic leukemia based on results of a complete blood cell count and cytologic examination of a bone marrow aspirate. Treatment with oral chlorambucil was attempted, but no response was evident after 40 days. The bird was euthanatized, and the diagnosis of chronic lymphocytic leukemia was confirmed on gross and microscopic examination of tissues. Neoplastic lymphocytes were found in the bone marrow, liver, kidney, testes, and blood vessels. Based on CD3-positive immunocytochemical and immunohistochemical immunophenotyping, the chronic lymphocytic leukemia was determined to be of T-cell origin.

Cadmium recovery by coupling double microbial fuel cells.

PubMed

Choi, Chansoo; Hu, Naixu; Lim, Bongsu

2014-10-01

Cr(VI)-MFC of the double microbial fuel cell (d-MFC) arrangement could successfully complement the insufficient voltage and power needed to recover cadmium metal from Cd(II)-MFC, which operated as a redox-flow battery. It was also possible to drain electrical energy from the d-MFC by an additional passage. The highest maximum utilization power density (22.5Wm(-2)) of Cr(VI)-MFC, with the cathode optimized with sulfate buffer, was 11.3times higher than the highest power density directly supplied to Cd(II)-MFC (2.0Wm(-2)). Cr(VI)-MFC could generate 3times higher power with the additional passage than without it; and the current density for the former was 4.2times higher than the latter at the same maximum power point (38.0Am(-2) vs. 9.0Am(-2)). This boosting phenomenon could be explained by the Le Chatelier's principle, which addresses the rate of electron-hole pair formation that can be accelerated by quickly removing electrons generated by microorganisms. Copyright © 2014 Elsevier Ltd. All rights reserved.

Double Knockdown of Prolyyl Hydroxylase and Factor Inhibiting HIF with Non-Viral Minicircle Gene Therapy Enhances Stem Cell Mobilization and Angiogenesis After Myocardial Infarction

PubMed Central

Huang, Mei; Nguyen, Patricia; Jia, Fangjun; Hu, Shijun; Gong, Yongquan; de Almeida, Patricia E.; Wang, Li; Nag, Divya; Kay, Mark A.; Giaccia, Amato J; Robbins, Robert C.; Wu, Joseph C.

2011-01-01

Background Under normoxic conditions, hypoxia inducible factor-1 alpha (HIF-1α) is rapidly degraded by two hydroxylases, prolyl hydroxylase (PHD) and factor inhibiting HIF-1 (FIH). Because HIF-1α mediates the cardioprotective response to ischemic injury, its up-regulation may be an effective therapeutic option for ischemic heart failure. Methods and Results PHD and FIH were cloned from mouse embryonic stem cells. The best candidate short hairpin sequences for inhibiting PHD isoenzyme 2 (shPHD2) and FIH (shFIH) were inserted into novel non-viral minicircle vectors. In vitro studies after cell transfection of mouse C2C12 myoblasts, HL-1 atrial myocytes, and c-kit+ cardiac progenitor cells (CPCs) demonstrated higher expression of angiogenesis factors in the double knockdown group compared to the single knockdown and shScramble control groups. To confirm in vitro data, shRNA minicircle vectors were injected intramyocardially following LAD ligation in adult FVB mice (n=60). Functional studies using magnetic resonance imaging (MRI), echocardiography, and pressure-volume (PV) loops showed greater improvement in cardiac function in the double knockdown group. To assess mechanism(s) of this functional recovery, we performed a cell trafficking experiment, which demonstrated significantly greater recruitment of bone marrow cells to the ischemic myocardium in the double knockdown group. Fluorescence activated cell sorting (FACS) showed significantly higher activation of endogenous c-kit+ cardiac progenitor cells. Immunostaining showed increased neovascularization and decreased apoptosis in areas of injured myocardium. Finally, western blots and laser capture microdissection (LCM) analysis confirmed up-regulation of HIF-1α protein and angiogenesis genes, respectively. Conclusions We demonstrated that HIF-1α up-regulation by double knockdown of PHD and FIH synergistically increases stem cell mobilization and myocardial angiogenesis, leading to improved cardiac function. PMID

A highly durable fuel cell electrocatalyst based on double-polymer-coated carbon nanotubes.

PubMed

Berber, Mohamed R; Hafez, Inas H; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

2015-11-23

Driven by the demand for the commercialization of fuel cell (FC) technology, we describe the design and fabrication of a highly durable FC electrocatalyst based on double-polymer-coated carbon nanotubes for use in polymer electrolyte membrane fuel cells. The fabricated electrocatalyst is composed of Pt-deposited polybenzimidazole-coated carbon nanotubes, which are further coated with Nafion. By using this electrocatalyst, a high FC performance with a power density of 375 mW/cm(2) (at 70 ˚C, 50% relative humidity using air (cathode)/H2(anode)) was obtained, and a remarkable durability of 500,000 accelerated potential cycles was recorded with only a 5% loss of the initial FC potential and 20% loss of the maximum power density, which were far superior properties compared to those of the membrane electrode assembly prepared using carbon black in place of the carbon nanotubes. The present study indicates that the prepared highly durable fuel cell electrocatalyst is a promising material for the next generation of PEMFCs.

Single- and double-ion type cross-linked polysiloxane solid electrolytes for lithium cells

NASA Astrophysics Data System (ADS)

Tsutsumi, Hiromori; Yamamoto, Masahiro; Morita, Masayuki; Matsuda, Yoshiharu; Nakamura, Takashi; Asai, Hiroyuki

Polymeric solid electrolytes, that have poly(dimethylsiloxane) (PMS) backbone and cross-linked network, were applied to a rechargeable lithium battery system. Single- (PMS-Li) and double-ion type (PMS-LiClO 4) electrolytes were prepared from the same prepolymers. Lithium electrode in the both electrolytes showed reversible stripping and deposition of lithium. Intercalation and deintercalation processes of lithium ion between lithium-manganese composite oxide (Li xMnO 2) electrode and the electrolytes were also confirmed by cyclic voltammetry, however, peak current decreased with several cycles in both cases. The model cell, Li/PMS-Li/Li xMnO 2 cell had 1.4 mA h g -1 (per 1 g of active material, current density: 3.77 μA cm -2), and the Li/PMS-LiClO 4/Li xMnO 2 cell had 1.6 mA h g -1 (current density: 75.3 μA cm -2).

A dynamic response model for pressure sensors in continuum and high Knudsen number flows with large temperature gradients

NASA Technical Reports Server (NTRS)

Whitmore, Stephen A.; Petersen, Brian J.; Scott, David D.

1996-01-01

This paper develops a dynamic model for pressure sensors in continuum and rarefied flows with longitudinal temperature gradients. The model was developed from the unsteady Navier-Stokes momentum, energy, and continuity equations and was linearized using small perturbations. The energy equation was decoupled from momentum and continuity assuming a polytropic flow process. Rarefied flow conditions were accounted for using a slip flow boundary condition at the tubing wall. The equations were radially averaged and solved assuming gas properties remain constant along a small tubing element. This fundamental solution was used as a building block for arbitrary geometries where fluid properties may also vary longitudinally in the tube. The problem was solved recursively starting at the transducer and working upstream in the tube. Dynamic frequency response tests were performed for continuum flow conditions in the presence of temperature gradients. These tests validated the recursive formulation of the model. Model steady-state behavior was analyzed using the final value theorem. Tests were performed for rarefied flow conditions and compared to the model steady-state response to evaluate the regime of applicability. Model comparisons were excellent for Knudsen numbers up to 0.6. Beyond this point, molecular affects caused model analyses to become inaccurate.

A Novel Double Subculture Method and Its Theory for the Enumeration of Injured Cells in Stressed Microbial Population.

PubMed

Tsuchido, Tetsuaki

2017-01-01

　A novel double subculture method, termed DiVSaL (Differential Viabilities between Solid and Liquid media) method, for the enumeration of injured cell population of a microorganism, which occurs after some sublethal to lethal treatment, was proposed. In this method injured cells were enumerated as the differential value between viabilities determined with two different techniques, the conventional plate counting using a solid agar medium and the growth delay analysis using a liquid medium. In the former technique, the viable cell number is obtained as colony forming unit (CFU) formed on an agar medium where sublethally injured cells are as much rescued as possible. In the latter technique, on the other hand," the integrated viability" defined by Takano and Tsuchido (1982) is introduced and is calculated from the growth delay of a stressed population, referred to unstressed one. For the growth delay analysis, in this paper, not only the original theoretical model, where the specific growth rate (and therefore the defined G 10 value) does not change after the exposure to a stress treatment, but also a novel modified theory, where the parameter changes, is proposed. On the theoretical background, this DiVSaL method as a double subculture method can be used to enumerate the injured cells without selection by addition of some inhibitor or by nutritional shortage.

Intestinal double-positive CD4+CD8+ T cells are highly activated memory cells with an increased capacity to produce cytokines.

PubMed

Pahar, Bapi; Lackner, Andrew A; Veazey, Ronald S

2006-03-01

Peripheral blood and intestinal CD4+CD8+ double-positive (DP) T cells have been described in several species including humans, but their function and immunophenotypic characteristics are still not clearly understood. Here we demonstrate that DP T cells are abundant in the intestinal lamina propria of normal rhesus macaques (Macaca mulatta). Moreover, DP T cells have a memory phenotype and are capable of producing different and/or higher levels of cytokines and chemokines in response to mitogen stimulation compared to CD4+ single-positive T cells. Intestinal DP T cells are also highly activated and have higher expression of CCR5, which makes them preferred targets for simian immunodeficiency virus/HIV infection. Increased levels of CD69, CD25 and HLA-DR, and lower CD62L expression were found on intestinal DP T cells populations compared to CD4+ single-positive T cells. Collectively, these findings demonstrate that intestinal and peripheral blood DP T cells are effector cells and may be important in regulating immune responses, which distinguishes them from the immature DP cells found in the thymus. Finally, these intestinal DP T cells may be important target cells for HIV infection and replication due to their activation, memory phenotype and high expression of CCR5.

Color in the Cortex—single- and double-opponent cells

PubMed Central

Shapley, Robert; Hawken, Michael

2011-01-01

This is a review of the research during the past 25 years on cortical processing of color signals. At the beginning of the period the modular view of cortical processing predominated. However, at present an alternative view, that color and form are linked inextricably in visual cortical processing, is more persuasive than it seemed in 1985. Also, the role of the primary visual cortex, V1, in color processing now seems much larger than it did in 1985. The re-evaluation of the important role of V1 in color vision was caused in part by investigations of human V1 responses to color, measured with functional magnetic resonance imaging, fMRI, and in part by the results of numerous studies of single-unit neurophysiology in non-human primates. The neurophysiological results have highlighted the importance of double-opponent cells in V1. Another new concept is population coding of hue, saturation, and brightness in cortical neuronal population activity. PMID:21333672

Investigation of the double exponential in the current-voltage characteristics of silicon solar cells. [proton irradiation effects on ATS 1 cells

NASA Technical Reports Server (NTRS)

Wolf, M.; Noel, G. T.; Stirn, R. J.

1977-01-01

Difficulties in relating observed current-voltage characteristics of individual silicon solar cells to their physical and material parameters were underscored by the unexpected large changes in the current-voltage characteristics telemetered back from solar cells on the ATS-1 spacecraft during their first year in synchronous orbit. Depletion region recombination was studied in cells exhibiting a clear double-exponential dark characteristic by subjecting the cells to proton irradiation. A significant change in the saturation current, an effect included in the Sah, Noyce, Shockley formulation of diode current resulting from recombination in the depletion region, was caused by the introduction of shallow levels in the depletion region by the proton irradiation. This saturation current is not attributable only to diffusion current from outside the depletion region and only its temperature dependence can clarify its origin. The current associated with the introduction of deep-lying levels did not change significantly in these experiments.

Simulation of plasma double-layer structures

NASA Technical Reports Server (NTRS)

Borovsky, J. E.; Joyce, G.

1982-01-01

Electrostatic plasma double layers are numerically simulated by means of a magnetized 2 1/2 dimensional particle in cell method. The investigation of planar double layers indicates that these one dimensional potential structures are susceptible to periodic disruption by instabilities in the low potential plasmas. Only a slight increase in the double layer thickness with an increase in its obliqueness to the magnetic field is observed. Weak magnetization results in the double layer electric field alignment of accelerated particles and strong magnetization results in their magnetic field alignment. The numerical simulations of spatially periodic two dimensional double layers also exhibit cyclical instability. A morphological invariance in two dimensional double layers with respect to the degree of magnetization implies that the potential structures scale with Debye lengths rather than with gyroradii. Electron beam excited electrostatic electron cyclotron waves and (ion beam driven) solitary waves are present in the plasmas adjacent to the double layers.

The scaling of oblique plasma double layers

NASA Technical Reports Server (NTRS)

Borovsky, J. E.

1983-01-01

Strong oblique plasma double layers are investigated using three methods, i.e., electrostatic particle-in-cell simulations, numerical solutions to the Poisson-Vlasov equations, and analytical approximations to the Poisson-Vlasov equations. The solutions to the Poisson-Vlasov equations and numerical simulations show that strong oblique double layers scale in terms of Debye lengths. For very large potential jumps, theory and numerical solutions indicate that all effects of the magnetic field vanish and the oblique double layers follow the same scaling relation as the field-aligned double layers.

Novel Double-Hit Model of Radiation and Hyperoxia-Induced Oxidative Cell Damage Relevant to Space Travel

PubMed Central

Pietrofesa, Ralph A.; Velalopoulou, Anastasia; Lehman, Stacey L.; Arguiri, Evguenia; Solomides, Pantelis; Koch, Cameron J.; Mishra, Om P.; Koumenis, Constantinos; Goodwin, Thomas J.; Christofidou-Solomidou, Melpo

2016-01-01

Spaceflight occasionally requires multiple extravehicular activities (EVA) that potentially subject astronauts to repeated changes in ambient oxygen superimposed on those of space radiation exposure. We thus developed a novel in vitro model system to test lung cell damage following repeated exposure to radiation and hyperoxia. Non-tumorigenic murine alveolar type II epithelial cells (C10) were exposed to >95% O2 for 8 h only (O2), 0.25 Gy ionizing γ-radiation (IR) only, or a double-hit combination of both challenges (O2 + IR) followed by 16 h of normoxia (ambient air containing 21% O2 and 5% CO2) (1 cycle = 24 h, 2 cycles = 48 h). Cell survival, DNA damage, apoptosis, and indicators of oxidative stress were evaluated after 1 and 2 cycles of exposure. We observed a significant (p < 0.05) decrease in cell survival across all challenge conditions along with an increase in DNA damage, determined by Comet analysis and H2AX phosphorylation, and apoptosis, determined by Annexin-V staining, relative to cells unexposed to hyperoxia or radiation. DNA damage (GADD45α and cleaved-PARP), apoptotic (cleaved caspase-3 and BAX), and antioxidant (HO-1 and Nqo1) proteins were increased following radiation and hyperoxia exposure after 1 and 2 cycles of exposure. Importantly, exposure to combination challenge O2 + IR exacerbated cell death and DNA damage compared to individual exposures O2 or IR alone. Additionally levels of cell cycle proteins phospho-p53 and p21 were significantly increased, while levels of CDK1 and Cyclin B1 were decreased at both time points for all exposure groups. Similarly, proteins involved in cell cycle arrest was more profoundly changed with the combination challenges as compared to each stressor alone. These results correlate with a significant 4- to 6-fold increase in the ratio of cells in G2/G1 after 2 cycles of exposure to hyperoxic conditions. We have characterized a novel in vitro model of double-hit, low-level radiation and hyperoxia exposure that

Important parameters affecting the cell voltage of aqueous electrical double-layer capacitors

NASA Astrophysics Data System (ADS)

Wu, Tzu-Ho; Hsu, Chun-Tsung; Hu, Chi-Chang; Hardwick, Laurence J.

2013-11-01

This study discusses and demonstrates how the open-circuit potential and charges stored in the working potential window on positive and negative electrodes affect the cell voltage of carbon-based electrical double-layer capacitors (EDLCs) in aqueous electrolytes. An EDLC consisting of two activated carbon electrodes is employed as the model system for identifying these key parameters although the potential window of water decomposition can be simply determined by voltammetric methods. First, the capacitive performances of an EDLC with the same charge on positive and negative electrodes are evaluated by cyclic voltammetric, charge-discharge, electrochemical impedance spectroscopic (EIS) analyses, and inductance-capacitance-resistance meter (LCR meter). The principles for obtaining the highest acceptable cell voltage of such symmetric ECs with excellent reversibility and capacitor-like behaviour are proposed. Aqueous charge-balanced EDLCs can be operated as high as 2.0 V with high energy efficiency (about 90%) and only 4% capacitance loss after the 600-cycle stability checking. The necessity of charge balance (but not capacitance balance) for positive and negative electrodes is substantiated from the lower acceptable cell voltage of charge-unbalanced EDLCs.

Poor recognition of O6-isopropyl dG by MGMT triggers double strand break-mediated cell death and micronucleus induction in FANC-deficient cells

PubMed Central

Hashimoto, Kiyohiro; Sharma, Vyom; Sasanuma, Hiroyuki; Tian, Xu; Takata, Minoru; Takeda, Shunichi; Swenberg, James A.; Nakamura, Jun

2016-01-01

Isopropyl methanesulfonate (IPMS) is the most potent genotoxic compound among methanesulfonic acid esters. The genotoxic potential of alkyl sulfonate esters is believed to be due to their alkylating ability of the O6 position of guanine. Understanding the primary repair pathway activated in response to IPMS-induced DNA damage is important to profile the genotoxic potential of IPMS. In the present study, both chicken DT40 and human TK6 cell-based DNA damage response (DDR) assays revealed that dysfunction of the FANC pathway resulted in higher sensitivity to IPMS compared to EMS or MMS. O6-alkyl dG is primarily repaired by methyl guanine methyltransferase (MGMT), while isopropyl dG is less likely to be a substrate for MGMT. Comparison of the cytotoxic potential of IPMS and its isomer n-propyl methanesulfonate (nPMS) revealed that the isopropyl moiety avoids recognition by MGMT and leads to higher cytotoxicity. Next, the micronucleus (MN) assay showed that FANC deficiency increases the sensitivity of DT40 cells to MN induction by IPMS. Pretreatment with O6-benzyl guanine (OBG), an inhibitor of MGMT, increased the MN frequency in DT40 cells treated with nPMS, but not IPMS. Lastly, IPMS induced more double strand breaks in FANC-deficient cells compared to wild-type cells in a time-dependent manner. All together, these results suggest that IPMS-derived O6-isopropyl dG escapes recognition by MGMT, and the unrepaired DNA damage leads to double strand breaks, resulting in MN induction. FANC, therefore, plays a pivotal role in preventing MN induction and cell death caused by IPMS. PMID:27486975

Rare transformation to double hit lymphoma in Waldenstrom's macroglobulinemia.

PubMed

Okolo, Onyemaechi N; Johnson, Ariel C; Yun, Seongseok; Arnold, Stacy J; Anwer, Faiz

2017-08-01

Waldenström macroglobulinemia (WM) is a lymphoproliferative lymphoma that is characterized by monoclonal immunoglobulin M (IgM) protein and bone marrow infiltration. Its incidence is rare and rarer still is its ability to transform to a B-cell lymphoma, particularly the aggressive diffuse large B-cell lymphoma, which bodes a poor prognosis. When transformation includes mutations of MYC, BCL-2 and/or BCL-6, it is known as a 'double hit' or 'triple hit' lymphoma respectively. This paper presents a rare case of WM with mutations positive for MYC and BCL2, making it a case of double hit B-cell lymphoplasmacytic lymphoma with plasmatic differentiation without morphological transformation to aggressive histology like DLBCL. The paper also broadens to include discussions on current topics in the classification, diagnosis, possible causes of transformation, and treatment of WM, including transformation to double hit lymphoma. The significance of this case lies in that the presence of double hit lymphoma-like genetic mutations in WM have not been previously described in the literature and potentially such changes are harbinger of extra-nodal presentation, aggressive growth, and possibly poor prognosis, if data from other double-hit lymphoma are extrapolated.

Repair of DNA double-strand breaks and cell killing by charged particles

NASA Astrophysics Data System (ADS)

Eguchi-Kasai, K.; Murakami, M.; Itsukaichi, H.; Fukutsu, K.; Yatagai, F.; Kanai, T.; Ohara, H.; Sato, K.

It has been suggested that it is not simple double-strand breaks (dsb) but the non-reparable breaks which correlate well with the high biological effectiveness of high LET radiations for cell killing. We have compared the effects of charged particles on cell death in 3 pairs of cell lines which are normal or defective in the repair of DNA dsbs. For the cell lines SL3-147, M10, and SX10 which are deficient in DNA dsb repair, RBE values were close to unity for cell killing induced by charged particles with linear energy transfer (LET) up to 200 keV/mum and were even smaller than unity for the LET region greater than 300 keV/mum. The inactivation cross section (ICS) increased with LET for all 3 pairs. The ICS of dsb repair deficient mutants was always larger than that of their parents for all the LET ranges, but with increasing LET the difference in ICS between the mutant and its parent became smaller. Since a small difference in ICS remained at LET of about 300 keV/mum, dsb repair may still take place at this high LET, even if its role is apparently small. These results suggest that the DNA repair system does not play a major role in protection against the attack of high LET radiations and that a main cause of cell death is non-reparable dsb which are produced at a higher yield compared with low LET radiations. No correlation was observed between DNA content or nuclear area and ICS.

Relapsed or Refractory Double-Expressor and Double-Hit Lymphomas Have Inferior Progression-Free Survival After Autologous Stem-Cell Transplantation.

PubMed

Herrera, Alex F; Mei, Matthew; Low, Lawrence; Kim, Haesook T; Griffin, Gabriel K; Song, Joo Y; Merryman, Reid W; Bedell, Victoria; Pak, Christine; Sun, Heather; Paris, Tanya; Stiller, Tracey; Brown, Jennifer R; Budde, Lihua E; Chan, Wing C; Chen, Robert; Davids, Matthew S; Freedman, Arnold S; Fisher, David C; Jacobsen, Eric D; Jacobson, Caron A; LaCasce, Ann S; Murata-Collins, Joyce; Nademanee, Auayporn P; Palmer, Joycelynne M; Pihan, German A; Pillai, Raju; Popplewell, Leslie; Siddiqi, Tanya; Sohani, Aliyah R; Zain, Jasmine; Rosen, Steven T; Kwak, Larry W; Weinstock, David M; Forman, Stephen J; Weisenburger, Dennis D; Kim, Young; Rodig, Scott J; Krishnan, Amrita; Armand, Philippe

2017-01-01

Purpose Double-hit lymphomas (DHLs) and double-expressor lymphomas (DELs) are subtypes of diffuse large B-cell lymphoma (DLBCL) associated with poor outcomes after standard chemoimmunotherapy. Data are limited regarding outcomes of patients with relapsed or refractory (rel/ref) DEL or DHL who undergo autologous stem-cell transplantation (ASCT). We retrospectively studied the prognostic impact of DEL and DHL status on ASCT outcomes in patients with rel/ref DLBCL. Methods Patients with chemotherapy-sensitive rel/ref DLBCL who underwent ASCT at two institutions and in whom archival tumor material was available were enrolled. Immunohistochemistry for MYC, BCL2, and BCL6 and fluorescence in situ hybridization (FISH) for MYC were performed. In cases with MYC rearrangement or copy gain, FISH for BCL2 and BCL6 was also performed. Results A total of 117 patients were included; 44% had DEL and 10% had DHL. DEL and DHL were associated with inferior progression-free survival (PFS), and DHL was associated with poorer overall survival (OS). The 4-year PFS in patients with DEL compared with those with non-DEL was 48% versus 59% ( P = .049), and the 4-year OS was 56% versus 67% ( P = .10); 4-year PFS in patients with DHL compared with those with non-DHL was 28% versus 57% ( P = .013), and 4-year OS was 25% versus 61% ( P = .002). The few patients with concurrent DEL and DHL had a poor outcome (4-year PFS, 0%). In multivariable models, DEL and DHL were independently associated with inferior PFS, whereas DHL and partial response ( v complete response) at transplant were associated with inferior OS. Conclusion DEL and DHL are both associated with inferior outcomes after ASCT in patients with rel/ref DLBCL. Although ASCT remains a potentially curative approach, these patients, particularly those with DHL, are a high-risk subset who should be targeted for investigational strategies other than standard ASCT.

Relapsed or Refractory Double-Expressor and Double-Hit Lymphomas Have Inferior Progression-Free Survival After Autologous Stem-Cell Transplantation

PubMed Central

Herrera, Alex F.; Mei, Matthew; Low, Lawrence; Kim, Haesook T.; Griffin, Gabriel K.; Song, Joo Y.; Merryman, Reid W.; Bedell, Victoria; Pak, Christine; Sun, Heather; Paris, Tanya; Stiller, Tracey; Brown, Jennifer R.; Budde, Lihua E.; Chan, Wing C.; Chen, Robert; Davids, Matthew S.; Freedman, Arnold S.; Fisher, David C.; Jacobsen, Eric D.; Jacobson, Caron A.; LaCasce, Ann S.; Murata-Collins, Joyce; Nademanee, Auayporn P.; Palmer, Joycelynne M.; Pihan, German A.; Pillai, Raju; Popplewell, Leslie; Siddiqi, Tanya; Sohani, Aliyah R.; Zain, Jasmine; Rosen, Steven T.; Kwak, Larry W.; Weinstock, David M.; Forman, Stephen J.; Weisenburger, Dennis D.; Kim, Young; Rodig, Scott J.; Krishnan, Amrita

2017-01-01

Purpose Double-hit lymphomas (DHLs) and double-expressor lymphomas (DELs) are subtypes of diffuse large B-cell lymphoma (DLBCL) associated with poor outcomes after standard chemoimmunotherapy. Data are limited regarding outcomes of patients with relapsed or refractory (rel/ref) DEL or DHL who undergo autologous stem-cell transplantation (ASCT). We retrospectively studied the prognostic impact of DEL and DHL status on ASCT outcomes in patients with rel/ref DLBCL. Methods Patients with chemotherapy-sensitive rel/ref DLBCL who underwent ASCT at two institutions and in whom archival tumor material was available were enrolled. Immunohistochemistry for MYC, BCL2, and BCL6 and fluorescence in situ hybridization (FISH) for MYC were performed. In cases with MYC rearrangement or copy gain, FISH for BCL2 and BCL6 was also performed. Results A total of 117 patients were included; 44% had DEL and 10% had DHL. DEL and DHL were associated with inferior progression-free survival (PFS), and DHL was associated with poorer overall survival (OS). The 4-year PFS in patients with DEL compared with those with non-DEL was 48% versus 59% (P = .049), and the 4-year OS was 56% versus 67% (P = .10); 4-year PFS in patients with DHL compared with those with non-DHL was 28% versus 57% (P = .013), and 4-year OS was 25% versus 61% (P = .002). The few patients with concurrent DEL and DHL had a poor outcome (4-year PFS, 0%). In multivariable models, DEL and DHL were independently associated with inferior PFS, whereas DHL and partial response (v complete response) at transplant were associated with inferior OS. Conclusion DEL and DHL are both associated with inferior outcomes after ASCT in patients with rel/ref DLBCL. Although ASCT remains a potentially curative approach, these patients, particularly those with DHL, are a high-risk subset who should be targeted for investigational strategies other than standard ASCT. PMID:28034071

A highly durable fuel cell electrocatalyst based on double-polymer-coated carbon nanotubes

PubMed Central

Berber, Mohamed R.; Hafez, Inas H.; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

2015-01-01

Driven by the demand for the commercialization of fuel cell (FC) technology, we describe the design and fabrication of a highly durable FC electrocatalyst based on double-polymer-coated carbon nanotubes for use in polymer electrolyte membrane fuel cells. The fabricated electrocatalyst is composed of Pt-deposited polybenzimidazole-coated carbon nanotubes, which are further coated with Nafion. By using this electrocatalyst, a high FC performance with a power density of 375 mW/cm2 (at 70 ˚C, 50% relative humidity using air (cathode)/H2(anode)) was obtained, and a remarkable durability of 500,000 accelerated potential cycles was recorded with only a 5% loss of the initial FC potential and 20% loss of the maximum power density, which were far superior properties compared to those of the membrane electrode assembly prepared using carbon black in place of the carbon nanotubes. The present study indicates that the prepared highly durable fuel cell electrocatalyst is a promising material for the next generation of PEMFCs. PMID:26594045

Inactivation, DNA double strand break induction and their rejoining in bacterial cells irradiated with heavy ions

NASA Technical Reports Server (NTRS)

Schaefer, M.; Zimmermann, H.; Schmitz, C.

1994-01-01

Besides inactivation one of the major interests in our experiments is to study the primary damage in the DNA double strand breaks (DSB) after heavy ion irradiation. These damages lead not only to cell death but also under repair activities to mutations. In further experiments we have investigated the inactivation with two different strains of Deinococcus radiodurans (R1, Rec 30) and the induction of DSB as well as the rejoining of DSB in stationary cells of E. coli (strain B/r) irradiated with radiations of different quality. In the latter case irradiations were done so that the cell survival was roughly at the same level. We measured the DSB using the pulse field gelelectrophoresis which allows to separate between intact (circular) and damaged (linear) DNA. The irradiated cells were transferred to NB medium and incubated for different times to allow rejoining.

Hsp90 N- and C-terminal double inhibition synergistically suppresses Bcr-Abl-positive human leukemia cells

PubMed Central

Chen, Xianling; Chen, Xiaole; Li, Ding; Fan, Yingjuan; Xu, Jianhua; Chen, Yuanzhong; Wu, Lixian

2017-01-01

Heat shock protein 90 (Hsp90) contains amino (N)–terminal domain, carboxyl(C)-terminal domain, and middle domains, which activate Hsp90 chaperone function cooperatively in tumor cells. One terminal occupancy might influence another terminal binding with inhibitor. The Bcr-Abl kinase is one of the Hsp90 clients implicated in the pathogenesis of chronic myeloid leukemia (CML). Present studies demonstrate that double inhibition of the N- and C-terminal termini can disrupt Hsp90 chaperone function synergistically, but not antagonistically, in Bcr-Abl-positive human leukemia cells. Furthermore, both the N-terminal inhibitor 17-AAG and the C-terminal inhibitor cisplatin (CP) have the capacity to suppress progenitor cells; however, only CP is able to inhibit leukemia stem cells (LSCs) significantly, which implies that the combinational treatment is able to suppress human leukemia in different mature states. PMID:28036294

DNA double-strand break response in stem cells: mechanisms to maintain genomic integrity.

PubMed

Nagaria, Pratik; Robert, Carine; Rassool, Feyruz V

2013-02-01

Embryonic stem cells (ESCs) represent the point of origin of all cells in a given organism and must protect their genomes from both endogenous and exogenous genotoxic stress. DNA double-strand breaks (DSBs) are one of the most lethal forms of damage, and failure to adequately repair DSBs would not only compromise the ability of SCs to self-renew and differentiate, but will also lead to genomic instability and disease. Herein, we describe the mechanisms by which ESCs respond to DSB-inducing agents such as reactive oxygen species (ROS) and ionizing radiation, compared to somatic cells. We will also discuss whether the DSB response is fully reprogrammed in induced pluripotent stem cells (iPSCs) and the role of the DNA damage response (DDR) in the reprogramming of these cells. ESCs have distinct mechanisms to protect themselves against DSBs and oxidative stress compared to somatic cells. The response to damage and stress is crucial for the maintenance of self-renewal and differentiation capacity in SCs. iPSCs appear to reprogram some of the responses to genotoxic stress. However, it remains to be determined if iPSCs also retain some DDR characteristics of the somatic cells of origin. The mechanisms regulating the genomic integrity in ESCs and iPSCs are critical for its safe use in regenerative medicine and may shed light on the pathways and factors that maintain genomic stability, preventing diseases such as cancer. This article is part of a Special Issue entitled Biochemistry of Stem Cells. Copyright © 2012 Elsevier B.V. All rights reserved.

Light scattering management of dye-sensitized solar cells based on double-layered photoanodes aided by uniform TiO{sub 2} aggregates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakhshayesh, A.M., E-mail: bakhshayesh@alum.sharif.edu

2016-01-15

Highlights: • A new architecture of double-layered TiO{sub 2} electrodes is presented. • The electrode contains two alternate layers of TiO{sub 2} nanoparticles and aggregates. • The aggregates layers are deposited onto the nanocrystalline layer. • The new design showed improved efficiency compared to conventional cells. - Abstract: This study presents a new double-layered TiO{sub 2} film containing a nanocrystalline under-layer and a uniform, sponge-like light scattering over-layer for dye-sensitized solar cells (DSCs) application. The over-layer is composed of 2-μm-diameter uniform aggregates, containing small nanoparticles with the average grain size of 20 nm. X-ray diffraction reveals that the light scatteringmore » layer has a mixture of anatase and rutile phases, whereas the nanocrystalline layer has a pure anatase phase. Ultraviolet–visible (UV–vis) spectra show that the light scattering layer has lower band gap energy than the nanocrystalline under-layer, extending the absorption of TiO{sub 2} into visible region. Diffuse reflectance spectroscopy demonstrates that the double-layered electrode enjoyed better light scattering ability. The double-layered DSC shows the highest power conversion efficiency of 7.69% and incident photon-to-current efficiency of 88% as a result of higher light harvesting and less recombination which is demonstrated by electrochemical impedance spectroscopy.« less

Characterization of circulating CD4+ CD8+ double positive and CD4- CD8- double negative T-lymphocyte in children with β-thalassemia major.

PubMed

Zahran, Asmaa M; Saad, Khaled; Elsayh, Khalid I; Alblihed, Mohamd A

2017-03-01

Infectious complications represent the second most common cause of mortality and a major cause of morbidity in β-thalassemia major (BTM), with a prevalence of 12-13%. The data on unconventional T-lymphocyte subsets in BTM children are limited. The aim of the present study was to investigate and evaluate phenotypic alterations in CD4 + CD8 + double positive (DP), CD4 - CD8 - double negative (DN), and natural killer T-lymphocytes (NKT) in BTM children in comparison to healthy controls. Our case control study included 80 children with BTM and 40 healthy children as controls. Assessment of unconventional T-lymphocyte populations was done using sensitive four-color flow cytometry (FACSCalibur). Our analysis of the data showed a significantly higher frequency CD4 + CD8 + (double-positive) T cells, CD4 - CD8 - (double negative) T cells, and natural killer T cells in the peripheral blood of both BTM groups (splenectomized and non-splenectomized) as compared to healthy controls, suggesting that these cells may play a role in the clinical course of BTM. The relationship of the unconventional T-lymphocytes to immune disorders in BTM children remains to be determined. Further longitudinal study with a larger sample size is warranted to elucidate the role these cells in BTM. TRIAL NUMBER: UMIN000018950.

Isolation and characterization of ventricular-like cells derived from NKX2-5eGFP/w and MLC2vmCherry/w double knock-in human pluripotent stem cells.

PubMed

Yamauchi, Kaori; Li, Junjun; Morikawa, Kumi; Liu, Li; Shirayoshi, Yasuaki; Nakatsuji, Norio; Elliott, David A; Hisatome, Ichiro; Suemori, Hirofumi

2018-01-01

Human pluripotent stem cell (hPSC)-derived cardiomyocytes (CMs) are a promising source for cell transplantation into the damaged heart, which has limited regenerative ability. Many methods have been developed to obtain large amounts of functional CMs from hPSCs for therapeutic applications. However, during the differentiation process, a mixed population of various cardiac cells, including ventricular, atrial, and pacemaker cells, is generated, which hampers the proper functional analysis and evaluation of cell properties. Here, we established NKX2-5 eGFP/w and MLC2v mCherry/w hPSC double knock-ins that allow for labeling, tracing, purification, and analysis of the development of ventricular cells from early to late stages. As with the endogenous transcriptional activities of these genes, MLC2v-mCherry expression following NKX2-5-eGFP expression was observed under previously established culture conditions, which mimic the in vivo cardiac developmental process. Patch-clamp and microelectrode array electrophysiological analyses showed that the NKX2-5 and MLC2v double-positive cells possess ventricular-like properties. The results demonstrate that the NKX2-5 eGFP/w and MLC2v mCherry/w hPSCs provide a powerful model system to capture region-specific cardiac differentiation from early to late stages. Our study would facilitate subtype-specific cardiac development and functional analysis using the hPSC-derived sources. Copyright © 2017 Elsevier Inc. All rights reserved.

Regulation of inflammatory factors by double-stranded RNA receptors in breast cancer cells.

PubMed

Venkatesh, Amritha; Nandigam, Harika; Muccioli, Maria; Singh, Manindra; Loftus, Tiffany; Lewis, Deana; Pate, Michelle; Benencia, Fabian

Malignant cells are not the only components of a tumor mass since other cells (e.g., fibroblasts, infiltrating leukocytes and endothelial cells) are also part of it. In combination with the extracellular matrix, all these cells constitute the tumor microenvironment. In the last decade the role of the tumor microenvironment in cancer progression has gained increased attention and prompted efforts directed to abrogate its deleterious effects on anti-cancer therapies. The immune system can detect and attack tumor cells, and tumor-infiltrating lymphocytes (particularly CD8 T cells) have been associated with improved survival or better response to therapies in colorectal, melanoma, breast, prostate and ovarian cancer patients among others. Contrariwise, tumor-associated myeloid cells (myeloid-derived suppressor cells [MDSCs], dendritic cells [DCs], macrophages) or lymphoid cells such as regulatory T cells can stimulate tumor growth via inhibition of immune responses against the tumor or by participating in tumor neoangiogenesis. Herewith we analyzed the chemokine profile of mouse breast tumors regarding their capacity to generate factors capable of attracting and sequestering DCs to their midst. Chemoattractants from tumors were investigated by molecular biology and immunological techniques and tumor infiltrating DCs were investigated for matched chemokine receptors. In addition, we investigated the inflammatory response of breast cancer cells, a major component of the tumor microenvironment, to double-stranded RNA stimulation. By using molecular biology techniques such as qualitative and quantitative PCR, PCR arrays, and immunological techniques (ELISA, cytokine immunoarrays) we examined the effects of dsRNA treatment on the cytokine secretion profiles of mouse and human breast cancer cells and non-transformed cells. We were able to determine that tumors generate chemokines that are able to interact with receptors present on the surface of tumor infiltrating DCs. We

Data-based mathematical modeling of vectorial transport across double-transfected polarized cells.

PubMed

Bartholomé, Kilian; Rius, Maria; Letschert, Katrin; Keller, Daniela; Timmer, Jens; Keppler, Dietrich

2007-09-01

Vectorial transport of endogenous small molecules, toxins, and drugs across polarized epithelial cells contributes to their half-life in the organism and to detoxification. To study vectorial transport in a quantitative manner, an in vitro model was used that includes polarized MDCKII cells stably expressing the recombinant human uptake transporter OATP1B3 in their basolateral membrane and the recombinant ATP-driven efflux pump ABCC2 in their apical membrane. These double-transfected cells enabled mathematical modeling of the vectorial transport of the anionic prototype substance bromosulfophthalein (BSP) that has frequently been used to examine hepatobiliary transport. Time-dependent analyses of (3)H-labeled BSP in the basolateral, intracellular, and apical compartments of cells cultured on filter membranes and efflux experiments in cells preloaded with BSP were performed. A mathematical model was fitted to the experimental data. Data-based modeling was optimized by including endogenous transport processes in addition to the recombinant transport proteins. The predominant contributions to the overall vectorial transport of BSP were mediated by OATP1B3 (44%) and ABCC2 (28%). Model comparison predicted a previously unrecognized endogenous basolateral efflux process as a negative contribution to total vectorial transport, amounting to 19%, which is in line with the detection of the basolateral efflux pump Abcc4 in MDCKII cells. Rate-determining steps in the vectorial transport were identified by calculating control coefficients. Data-based mathematical modeling of vectorial transport of BSP as a model substance resulted in a quantitative description of this process and its components. The same systems biology approach may be applied to other cellular systems and to different substances.

Double-Stranded RNA-Dependent Protein Kinase Regulates the Motility of Breast Cancer Cells

PubMed Central

Xu, Mei; Chen, Gang; Wang, Siying; Liao, Mingjun; Frank, Jacqueline A.; Bower, Kimberly A.; Zhang, Zhuo; Shi, Xianglin; Luo, Jia

2012-01-01

Double-stranded RNA (dsRNA)-dependent protein kinase (PKR) is an interferon-induced protein kinase that plays a central role in the anti-viral process. Due to its pro-apoptotic and anti-proliferative action, there is an increased interest in PKR modulation as an anti-tumor strategy. PKR is overexpressed in breast cancer cells; however, the role of PKR in breast cancer cells is unclear. The expression/activity of PKR appears inversely related to the aggressiveness of breast cancer cells. The current study investigated the role of PKR in the motility/migration of breast cancer cells. The activation of PKR by a synthesized dsRNA (PIC) significantly decreased the motility of several breast cancer cell lines (BT474, MDA-MB231 and SKBR3). PIC inhibited cell migration and blocked cell membrane ruffling without affecting cell viability. PIC also induced the reorganization of the actin cytoskeleton and impaired the formation of lamellipodia. These effects of PIC were reversed by the pretreatment of a selective PKR inhibitor. PIC also activated p38 mitogen-activated protein kinase (MAPK) and its downstream MAPK-activated protein kinase 2 (MK2). PIC-induced activation of p38 MAPK and MK2 was attenuated by the PKR inhibitor and the PKR siRNA, but a selective p38 MAPK inhibitor (SB203580) or other MAPK inhibitors did not affect PKR activity, indicating that PKR is upstream of p38 MAPK/MK2. Cofilin is an actin severing protein and regulates membrane ruffling, lamellipodia formation and cell migration. PIC inhibited cofilin activity by enhancing its phosphorylation at Ser3. PIC activated LIM kinase 1 (LIMK1), an upstream kinase of cofilin in a p38 MAPK-dependent manner. We concluded that the activation of PKR suppressed cell motility by regulating the p38 MAPK/MK2/LIMK/cofilin pathway. PMID:23112838

Normal and system lupus erythematosus red blood cell interactions studied by double trap optical tweezers: direct measurements of aggregation forces

NASA Astrophysics Data System (ADS)

Khokhlova, Maria D.; Lyubin, Eugeny V.; Zhdanov, Alexander G.; Rykova, Sophia Yu.; Sokolova, Irina A.; Fedyanin, Andrey A.

2012-02-01

Direct measurements of aggregation forces in piconewton range between two red blood cells in pair rouleau are performed under physiological conditions using double trap optical tweezers. Aggregation and disaggregation properties of healthy and pathologic (system lupus erythematosis) blood samples are analyzed. Strong difference in aggregation speed and behavior is revealed using the offered method which is proposed to be a promising tool for SLE monitoring at single cell level.

Investigation of the vaporization of boric acid by transpiration thermogravimetry and knudsen effusion mass spectrometry.

PubMed

Balasubramanian, R; Lakshmi Narasimhan, T S; Viswanathan, R; Nalini, S

2008-11-06

The vaporization of H3BO3(s) was studied by using a commercial thermogravimetric apparatus and a Knudsen effusion mass spectrometer. The thermogravimetric measurements involved use of argon as the carrier gas for vapor transport and derivation of vapor pressures of H3BO3(g) in the temperature range 315-352 K through many flow dependence and temperature dependence runs. The vapor pressures as well as the enthalpy of sublimation obtained in this study represent the first results from measurements at low temperatures that are in accord with the previously reported near-classical transpiration measurements (by Stackelberg et al. 70 years ago) at higher temperatures (382-413 K with steam as the carrier gas). The KEMS measurements performed for the first time on boric acid showed H3BO3(g) as the principal vapor species with no meaningful information discernible on H2O(g) though. The thermodynamic parameters, both p(H3BO3) and Delta sub H degrees m(H3BO3,g), deduced from KEMS results in the temperature range 295-342 K are in excellent agreement with the transpiration results lending further credibility to the latter. All this information points toward congruent vaporization at the H3BO3 composition in the H2O-B2O3 binary system. The vapor pressures obtained from transpiration (this study and that of Stackelberg et al.) as well as from KEMS measurements are combined to recommend the following: log [p(H3BO3)/Pa]=-(5199+/-74)/(T/K)+(15.65+/-0.23), valid for T=295-413 K; and Delta sub H degrees m=98.3+/-9.5 kJ mol (-1) at T=298 K for H3BO3(s)=H3BO3(g).

Improved performance of CdSe/CdS/PbS co-sensitized solar cell with double-layered TiO2 films as photoanode

NASA Astrophysics Data System (ADS)

Zhang, Xiaolong; Lin, Yu; Wu, Jihuai; Jing, Jing; Fang, Biaopeng

2017-07-01

Improving the photovoltaic performance of CdSe/CdS/PbS co-sensitized double-layered TiO2 solar cells is reported. Double-layered TiO2 films with TiO2 microspheres as the light blocking layers were prepared. PbS, CdS and CdSe quantum dots (QDs) were assembled onto TiO2 photoanodes by simple successive ionic layer absorption and reaction (SILAR) to fabricate CdSe/CdS/PbS co-sensitized solar cells. An improved power conversion efficiency (PCE) of 5.11% was achieved for CdSe/CdS/PbS co-sensitized solar cells at one sun illumination (AM 1.5 G, 100 mW cm-2), which had an improvement of 22.6% over that of the CdSe/CdS co-sensitized solar cells (4.17%). This enhancement is mainly attributed to their better ability of the absorption of solar light with the existence of PbS QDs, the reduction of charge recombination of the excited electron and longer lifetime of electrons, which have been proved with the photovoltaic studies and electrochemical impedance spectroscopy (EIS).

Placement-aware decomposition of a digital standard cells library for double patterning lithography

NASA Astrophysics Data System (ADS)

Wassal, Amr G.; Sharaf, Heba; Hammouda, Sherif

2012-11-01

To continue scaling the circuit features down, Double Patterning (DP) technology is needed in 22nm technologies and lower. DP requires decomposing the layout features into two masks for pitch relaxation, such that the spacing between any two features on each mask is greater than the minimum allowed mask spacing. The relaxed pitches of each mask are then processed on two separate exposure steps. In many cases, post-layout decomposition fails to decompose the layout into two masks due to the presence of conflicts. Post-layout decomposition of a standard cells block can result in native conflicts inside the cells (internal conflict), or native conflicts on the boundary between two cells (boundary conflict). Resolving native conflicts requires a redesign and/or multiple iterations for the placement and routing phases to get a clean decomposition. Therefore, DP compliance must be considered in earlier phases, before getting the final placed cell block. The main focus of this paper is generating a library of decomposed standard cells to be used in a DP-aware placer. This library should contain all possible decompositions for each standard cell, i.e., these decompositions consider all possible combinations of boundary conditions. However, the large number of combinations of boundary conditions for each standard cell will significantly increase the processing time and effort required to obtain all possible decompositions. Therefore, an efficient methodology is required to reduce this large number of combinations. In this paper, three different reduction methodologies are proposed to reduce the number of different combinations processed to get the decomposed library. Experimental results show a significant reduction in the number of combinations and decompositions needed for the library processing. To generate and verify the proposed flow and methodologies, a prototype for a placement-aware DP-ready cell-library is developed with an optimized number of cell views.

Low levels of endogenous or X-ray-induced DNA double-strand breaks activate apoptosis in adult neural stem cells.

PubMed

Barazzuol, Lara; Rickett, Nicole; Ju, Limei; Jeggo, Penny A

2015-10-01

The embryonic neural stem cell compartment is characterised by rapid proliferation from embryonic day (E)11 to E16.5, high endogenous DNA double-strand break (DSB) formation and sensitive activation of apoptosis. Here, we ask whether DSBs arise in the adult neural stem cell compartments, the sub-ventricular zone (SVZ) of the lateral ventricles and the sub-granular zone (SGZ) of the hippocampal dentate gyrus, and whether they activate apoptosis. We used mice with a hypomorphic mutation in DNA ligase IV (Lig4(Y288C)), ataxia telangiectasia mutated (Atm(-/-)) and double mutant Atm(-/-)/Lig4(Y288C) mice. We demonstrate that, although DSBs do not arise at a high frequency in adult neural stem cells, the low numbers of DSBs that persist endogenously in Lig4(Y288C) mice or that are induced by low radiation doses can activate apoptosis. A temporal analysis shows that DSB levels in Lig4(Y288C) mice diminish gradually from the embryo to a steady state level in adult mice. The neonatal SVZ compartment of Lig4(Y288C) mice harbours diminished DSBs compared to its differentiated counterpart, suggesting a process selecting against unfit stem cells. Finally, we reveal high endogenous apoptosis in the developing SVZ of wild-type newborn mice. © 2015. Published by The Company of Biologists Ltd.

Double bevel construction of a diamond anvil

DOEpatents

Moss, William C.

1988-01-01

A double or multiple bevel culet geometry is used on a diamond anvil in a high pressure cell apparatus to provide increased sample pressure and stability for a given force applied to the diamond tables. Double or multiple bevel culet geometries can also be used for sapphire or other hard crystal anvils. Pressures up to and above 5 Megabars can be reached.

Sulforaphane induces DNA double strand breaks predominantly repaired by homologous recombination pathway in human cancer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sekine-Suzuki, Emiko; Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522; Yu, Dong

2008-12-12

Cytotoxicity and DNA double strand breaks (DSBs) were studied in HeLa cells treated with sulforaphane (SFN), a well-known chemo-preventive agent. Cell survival was impaired by SFN in a concentration and treatment time-dependent manner. Both constant field gel electrophoresis (CFGE) and {gamma}-H2AX assay unambiguously indicated formation of DSBs by SFN, reflecting the cell survival data. These DSBs were predominantly processed by homologous recombination repair (HRR), judging from the SFN concentration-dependent manner of Rad51 foci formation. On the other hand, the phosphorylation of DNA-PKcs, a key non-homologous end joining (NHEJ) protein, was not observed by SFN treatment, suggesting that NHEJ may notmore » be involved in DSBs induced by this chemical. G2/M arrest by SFN, a typical response for cells exposed to ionizing radiation was also observed. Our new data indicate the clear induction of DSBs by SFN and a useful anti-tumor aspect of SFN through the induction of DNA DSBs.« less

Aging impairs double-strand break repair by homologous recombination in Drosophila germ cells.

PubMed

Delabaere, Laetitia; Ertl, Henry A; Massey, Dashiell J; Hofley, Carolyn M; Sohail, Faraz; Bienenstock, Elisa J; Sebastian, Hans; Chiolo, Irene; LaRocque, Jeannine R

2017-04-01

Aging is characterized by genome instability, which contributes to cancer formation and cell lethality leading to organismal decline. The high levels of DNA double-strand breaks (DSBs) observed in old cells and premature aging syndromes are likely a primary source of genome instability, but the underlying cause of their formation is still unclear. DSBs might result from higher levels of damage or repair defects emerging with advancing age, but repair pathways in old organisms are still poorly understood. Here, we show that premeiotic germline cells of young and old flies have distinct differences in their ability to repair DSBs by the error-free pathway homologous recombination (HR). Repair of DSBs induced by either ionizing radiation (IR) or the endonuclease I-SceI is markedly defective in older flies. This correlates with a remarkable reduction in HR repair measured with the DR-white DSB repair reporter assay. Strikingly, most of this repair defect is already present at 8 days of age. Finally, HR defects correlate with increased expression of early HR components and increased recruitment of Rad51 to damage in older organisms. Thus, we propose that the defect in the HR pathway for germ cells in older flies occurs following Rad51 recruitment. These data reveal that DSB repair defects arise early in the aging process and suggest that HR deficiencies are a leading cause of genome instability in germ cells of older animals. © 2016 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

Activation of double-stranded RNA-dependent protein kinase inhibits proliferation of pancreatic β-cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Shan-Shan; Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing; Jiang, Teng

2014-01-17

Highlights: •PKR can be activated by glucolipitoxicity and pro-inflammatory cytokines in β-cells. •Activated PKR inhibited β-cell proliferation by arresting cell cycle at G1 phase. •Activated PKR fully abrogated the pro-proliferative effects of IGF-I on β-cells. -- Abstract: Double-stranded RNA-dependent protein kinase (PKR) is revealed to participate in the development of insulin resistance in peripheral tissues in type 2 diabetes (T2DM). Meanwhile, PKR is also characterized as a critical regulator of cell proliferation. To date, no study has focused on the impact of PKR on the proliferation of pancreatic β-cells. Here, we adopted insulinoma cell lines and mice islet β-cells tomore » investigate: (1) the effects of glucolipotoxicity and pro-inflammatory cytokines on PKR activation; (2) the effects of PKR on proliferation of pancreatic β-cells and its underlying mechanisms; (3) the actions of PKR on pro-proliferative effects of IGF-I and its underlying pathway. Our results provided the first evidence that PKR can be activated by glucolipitoxicity and pro-inflammatory cytokines in pancreatic β-cells, and activated PKR significantly inhibited cell proliferation by arresting cell cycle at G1 phase. Reductions in cyclin D1 and D2 as well as increases in p27 and p53 were associated with the anti-proliferative effects of PKR, and proteasome-dependent degradation took part in the reduction of cyclin D1 and D2. Besides, PKR activation abrogated the pro-proliferative effects of IGF-I by activating JNK and disrupting IRS1/PI3K/Akt signaling pathway. These findings indicate that the anti-proliferative actions of PKR on pancreatic β-cells may contribute to the pathogenesis of T2DM.« less

Differential repair of radiation-induced DNA damage in cells of human squamous cell carcinoma and the effect of caffeine and cysteamine on induction and repair of DNA double-strand breaks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smeets, M.F.M.A.; Mooren, E.H.M.; Abdel-Wahab, A.H.A.

1994-11-01

The goal of these experiments was to investigate further the relationship between DNA double-strand breaks and cell killing in human tumor cells, first by comparing different cell lines, and second by radiomodification studies. Field-inversion gel electrophoresis was used to quantify double-strand breaks. Two subclones of the radioresistant human squamous cell carcinoma line SQ20B (SQD9 and SQG6) were compared. These subclones differed in DNA index by a factor of 1.7 but showed the same resistance to radiation as cells of the parental cell line. It was found that, although induction of DSBs was not significantly different in the two cell lines,more » the t{sub 1/2} of the fast component of repair was significantly shorter for SQD9 cells, leading to greater overall repair which was not reflected in increased survival. Caffeine and cysteamine were tested as modifiers of radiosensitivity, using the radioresistant SQ20B line and the radiosensitive SCC61 cell line. No effect of caffeine was seen when the drug was present only during irradiation. Postirradiation incubations with caffeine, however, resulted in a dose reduction factor greater than 2.0 in cell survival for both cell lines. In contrast, induction of DSBs was reduced by caffeine, and no effect on DSB repair was observed. Cysteamine led to a dose protection factor greater than 1.8 in cell survival in both cell lines. A reduction in induced DSBs was found at high doses corresponding approximately with the increase in cell survival. Over the same (low) dose range, however, the correlation between DSB induction and cell killing was poor. These data indicate that DSB induction does not correlate well with cell killing either for different cell lines, for radiochemical modification (cysteamine) or for some other types of modification (caffeine). 31 refs., 8 figs.« less

Myricetin induces apoptosis via endoplasmic reticulum stress and DNA double-strand breaks in human ovarian cancer cells

PubMed Central

XU, YE; XIE, QI; WU, SHAOHUA; YI, DAN; YU, YANG; LIU, SHIBING; LI, SONGYAN; LI, ZHIXIN

2016-01-01

The mechanisms underlying myricetin-induced cancer cell apoptosis remain to be elucidated. Certain previous studies have shown that myricetin induces apoptosis through the mitochondrial pathway. Apoptosis, however, can also be induced by other classical pathways, including endoplasmic reticulum (ER) stress and DNA double-strand breaks (DSBs). The aim of the present study was to assess whether these two apoptotic pathways are involved in myricetin-induced cell death in SKOV3 ovarian cancer cells. The results revealed that treatment with myricetin inhibited viability of SKOV3 cells in a dose-dependent manner. Myricetin induced nuclear chromatin condensation and fragmentation, and also upregulated the protein levels of active caspase 3 in a time-dependent manner. In addition, myricetin upregulated ER stress-associated proteins, glucose-regulated protein-78 and C/EBP homologous protein in SKOV3 cells. Phosphorylation of H2AX, a marker of DNA DSBs, was revealed to be upregulated in myricetin-treated cells. The data indicated that myricetin induces DNA DSBs and ER stress, which leads to apoptosis in SKOV3 cells. PMID:26782830

Sustained release of stem cell factor in a double network hydrogel for ex vivo culture of cord blood-derived CD34+ cells.

PubMed

Zhang, Yuanhao; Pan, Xiuwei; Shi, Zhen; Cai, Haibo; Gao, Yun; Zhang, Weian

2018-04-01

Stem cell factor (SCF) is considered as a commonly indispensable cytokine for proliferation of haematopoietic stem cells (HSCs), which is used in large dosages during ex vivo culture. The work presented here aimed to reduce the consumption of SCF by sustained release but still support cells proliferation and maintain the multipotency of HSCs. Stem cell factor was physically encapsulated within a hyaluronic acid/gelatin double network (HGDN) hydrogel to achieve a slow release rate. CD34 + cells were cultured within the SCF-loaded HGDN hydrogel for 14 days. The cell number, phenotype and functional capacity were investigated after culture. The HGDN hydrogels had desirable properties and encapsulated SCF kept being released for more than 6 days. SCF remained the native bioactivity, and the proliferation of HSCs within the SCF-loaded HGDN hydrogel was not affected, although the consumption of SCF was only a quarter in comparison with the conventional culture. Moreover, CD34 + cells harvested from the SCF-loaded HGDN hydrogels generated more multipotent colony-forming units (CFU-GEMM). The data suggested that the SCF-loaded HGDN hydrogel could support ex vivo culture of HSCs, thus providing a cost-effective culture protocol for HSCs. © 2017 John Wiley & Sons Ltd.

Estimation of the radiation-induced DNA double-strand breaks number by considering cell cycle and absorbed dose per cell nucleus

PubMed Central

Mori, Ryosuke; Matsuya, Yusuke; Yoshii, Yuji; Date, Hiroyuki

2018-01-01

Abstract DNA double-strand breaks (DSBs) are thought to be the main cause of cell death after irradiation. In this study, we estimated the probability distribution of the number of DSBs per cell nucleus by considering the DNA amount in a cell nucleus (which depends on the cell cycle) and the statistical variation in the energy imparted to the cell nucleus by X-ray irradiation. The probability estimation of DSB induction was made following these procedures: (i) making use of the Chinese Hamster Ovary (CHO)-K1 cell line as the target example, the amounts of DNA per nucleus in the logarithmic and the plateau phases of the growth curve were measured by flow cytometry with propidium iodide (PI) dyeing; (ii) the probability distribution of the DSB number per cell nucleus for each phase after irradiation with 1.0 Gy of 200 kVp X-rays was measured by means of γ-H2AX immunofluorescent staining; (iii) the distribution of the cell-specific energy deposition via secondary electrons produced by the incident X-rays was calculated by WLTrack (in-house Monte Carlo code); (iv) according to a mathematical model for estimating the DSB number per nucleus, we deduced the induction probability density of DSBs based on the measured DNA amount (depending on the cell cycle) and the calculated dose per nucleus. The model exhibited DSB induction probabilities in good agreement with the experimental results for the two phases, suggesting that the DNA amount (depending on the cell cycle) and the statistical variation in the local energy deposition are essential for estimating the DSB induction probability after X-ray exposure. PMID:29800455

Estimation of the radiation-induced DNA double-strand breaks number by considering cell cycle and absorbed dose per cell nucleus.

PubMed

Mori, Ryosuke; Matsuya, Yusuke; Yoshii, Yuji; Date, Hiroyuki

2018-05-01

DNA double-strand breaks (DSBs) are thought to be the main cause of cell death after irradiation. In this study, we estimated the probability distribution of the number of DSBs per cell nucleus by considering the DNA amount in a cell nucleus (which depends on the cell cycle) and the statistical variation in the energy imparted to the cell nucleus by X-ray irradiation. The probability estimation of DSB induction was made following these procedures: (i) making use of the Chinese Hamster Ovary (CHO)-K1 cell line as the target example, the amounts of DNA per nucleus in the logarithmic and the plateau phases of the growth curve were measured by flow cytometry with propidium iodide (PI) dyeing; (ii) the probability distribution of the DSB number per cell nucleus for each phase after irradiation with 1.0 Gy of 200 kVp X-rays was measured by means of γ-H2AX immunofluorescent staining; (iii) the distribution of the cell-specific energy deposition via secondary electrons produced by the incident X-rays was calculated by WLTrack (in-house Monte Carlo code); (iv) according to a mathematical model for estimating the DSB number per nucleus, we deduced the induction probability density of DSBs based on the measured DNA amount (depending on the cell cycle) and the calculated dose per nucleus. The model exhibited DSB induction probabilities in good agreement with the experimental results for the two phases, suggesting that the DNA amount (depending on the cell cycle) and the statistical variation in the local energy deposition are essential for estimating the DSB induction probability after X-ray exposure.

Single nucleotide-level mapping of DNA double-strand breaks in human HEK293T cells.

PubMed

Pope, Bernard J; Mahmood, Khalid; Jung, Chol-Hee; Georgeson, Peter; Park, Daniel J

2017-03-01

Constitutional biological processes involve the generation of DNA double-strand breaks (DSBs). The production of such breaks and their subsequent resolution are also highly relevant to neurodegenerative diseases and cancer, in which extensive DNA fragmentation has been described Stephens et al. (2011), Blondet et al. (2001). Tchurikov et al. Tchurikov et al. (2011, 2013) have reported previously that frequent sites of DSBs occur in chromosomal domains involved in the co-ordinated expression of genes. This group report that hot spots of DSBs in human HEK293T cells often coincide with H3K4me3 marks, associated with active transcription Kravatsky et al. (2015) and that frequent sites of DNA double-strand breakage are likely to be relevant to cancer genomics Tchurikov et al. (2013, 2016) . Recently, they applied a RAFT (rapid amplification of forum termini) protocol that selects for blunt-ended DSB sites and mapped these to the human genome within defined co-ordinate 'windows'. In this paper, we re-analyse public RAFT data to derive sites of DSBs at the single-nucleotide level across the built genome for human HEK293T cells (https://figshare.com/s/35220b2b79eaaaf64ed8). This refined mapping, combined with accessory ENCODE data tracks and ribosomal DNA-related sequence annotations, will likely be of value for the design of clinically relevant targeted assays such as those for cancer susceptibility, diagnosis, treatment-matching and prognostication.

A double-pulse approach for electrotransfection.

PubMed

Pasquet, L; Bellard, E; Golzio, M; Rols, M P; Teissie, J

2014-12-01

Gene transfer and expression can be obtained by delivering calibrated electric pulses on cells in the presence of plasmids coding for the activity of interest. The electric treatment affects the plasma membrane and induces the formation of a transient complex between nucleic acids and the plasma membrane. It results in a delivery of the plasmid in the cytoplasm. Expression is only obtained if the plasmid is translocated inside the nucleus. This is a key limit in the process. We previously showed that delivery of a high-field short-duration electric pulse was inducing a structural alteration of the nuclear envelope. This study investigates if the double-pulse approach (first pulse to transfer the plasmid to the cytoplasm, and second pulse to induce the structural alteration of the envelope) was a way to enhance the protein expression using the green fluorescent protein as a reporter. We observed that not only the double-pulse approach induced the transfection of a lower number of cells but moreover, these transfected cells were less fluorescent than the cells treated only with the first pulse.

Double bevel construction of a diamond anvil

DOEpatents

Moss, W.C.

1988-10-11

A double or multiple bevel culet geometry is used on a diamond anvil in a high pressure cell apparatus to provide increased sample pressure and stability for a given force applied to the diamond tables. Double or multiple bevel culet geometries can also be used for sapphire or other hard crystal anvils. Pressures up to and above 5 Megabars can be reached. 8 figs.

More efficient repair of DNA double-strand breaks in skeletal muscle stem cells compared to their committed progeny.

PubMed

Vahidi Ferdousi, Leyla; Rocheteau, Pierre; Chayot, Romain; Montagne, Benjamin; Chaker, Zayna; Flamant, Patricia; Tajbakhsh, Shahragim; Ricchetti, Miria

2014-11-01

The loss of genome integrity in adult stem cells results in accelerated tissue aging and is possibly cancerogenic. Adult stem cells in different tissues appear to react robustly to DNA damage. We report that adult skeletal stem (satellite) cells do not primarily respond to radiation-induced DNA double-strand breaks (DSBs) via differentiation and exhibit less apoptosis compared to other myogenic cells. Satellite cells repair these DNA lesions more efficiently than their committed progeny. Importantly, non-proliferating satellite cells and post-mitotic nuclei in the fiber exhibit dramatically distinct repair efficiencies. Altogether, reduction of the repair capacity appears to be more a function of differentiation than of the proliferation status of the muscle cell. Notably, satellite cells retain a high efficiency of DSB repair also when isolated from the natural niche. Finally, we show that repair of DSB substrates is not only very efficient but, surprisingly, also very accurate in satellite cells and that accurate repair depends on the key non-homologous end-joining factor DNA-PKcs. Copyright © 2014. Published by Elsevier B.V.

Double interconnection fuel cell array

DOEpatents

Draper, R.; Zymboly, G.E.

1993-12-28

A fuel cell array is made, containing number of tubular, elongated fuel cells which are placed next to each other in rows (A, B, C, D), where each cell contains inner electrodes and outer electrodes, with solid electrolyte between the electrodes, where the electrolyte and outer electrode are discontinuous, having two portions, and providing at least two opposed discontinuities which contain at least two oppositely opposed interconnections contacting the inner electrode, each cell having only three metallic felt electrical connectors which contact surrounding cells, where each row is electrically connected to the other. 5 figures.

Aptamer cell sensor based on porous graphene oxide decorated ion-selective-electrode: Double sensing platform for cell and ion.

PubMed

Zhang, Rong; Gu, Yajun; Wang, Zhongrong; Li, Yueguo; Fan, Qingjie; Jia, Yunfang

2018-06-15

Enlightened by the emerging cell-ion detection based on ion-selective-electrode (ISE), an aptamer capturing and ISE transducing (AC&IT) strategy is proposed on the porous graphene oxide (PGO) decorated ISE (PGO-ISE), its performances in both cell and ion detections are examined by use of AS1411 targeted A549 cell detection and iodide-ISE as proof-of-concept. Firstly, GO flakes, exfoliated from graphite by modified Hummers method, are cross-linked by thiourea mediated hydrothermal process, to 3-dimension networked PGO which is identified by scanning-electron-microscope, UV-visible absorbance and X-ray photoelectron spectroscopy; its enhancing effect for cell capturing is evaluated by microscopy. Then, PGO-ISE is constructed by drop-coating PGO film on the surface of ISE and followed by covalently anchoring AS1411. Electrochemistry measurements for different state ISE (blank, PGO coated, AS1411 anchored and A549 captured) are performed by our home-made ISE-measuring system. It is demonstrated that the best cell-sensitivity in buffer is - 25.21 mV/log 10 C A549 (R 2 = 0.91), resolution in blood is 10 cells/ml. Interestingly, due to PGO's scaffold protection to the ionophore, I - -sensitivity is preserved as - 42.98 mV/pI (R 2 = 0.95, pI = -log 10 (C I )). Theoretical explanations are provided for the double-sensing phenomenon according to basic ISE principle. It is believed the PGO-ISE based aptamer cell sensor will be a promising experimental means for biomedical researches. Copyright © 2018. Published by Elsevier B.V.

Brilliant Blue G double staining enhances successful internal limiting membrane peeling with minimal adverse effect by low cellular permeability into live cells.

PubMed

Hisatomi, Toshio; Notomi, Shoji; Tachibana, Takashi; Oishi, Seiichiro; Asato, Ryo; Yamashita, Takehiro; Murakami, Yusuke; Ikeda, Yasuhiro; Enaida, Hiroshi; Sakamoto, Taiji; Ishibashi, Tatsuro

2015-02-01

Brilliant Blue G is used as a surgical adjuvant for retinal surgery. Although BBG double or multiple staining was reported, the effectiveness and safety of repeated staining is still elusive. To further examine the effectiveness and safety, we examined BBG in clinical cases in vivo, primary cell culture in vitro, and surgically resected specimen ex vivo. A retrospective interventional case series with in vitro and ex vivo studies were performed. Vitrectomy was performed in 28 cases of epiretinal membrane with BBG single to multiple staining. The surgically resected membranes were stained by BBG with or without cellular fixation. Primary cell cultures were examined with BBG and live/death cell markers, such as Calcein AM and TUNEL. Single staining provided satisfactory staining in seven cases. Double or multiple staining substantially visualized internal limiting membrane (21 cases), especially the edges of remaining internal limiting membrane (11 cases). Adverse retinal staining was not noted and the final visual acuity showed no difference with multiple staining. The live cells barely stained with BBG, while some dead cells were stained. Brilliant Blue G multiple staining substantially enhanced the visualization of internal limiting membrane. The absence of abnormal staining supports the safety of repeated BBG staining.

Performance of microbial fuel cell double chamber using mozzarella cheese whey substrate

NASA Astrophysics Data System (ADS)

Darmawan, M. D.; Hawa, L. C.; Argo, B. D.

2018-03-01

Nowadays the availability of electric energy is decreasing, hence there is a need for innovation of electric energy producer alternative; one of them is microbial fuel cell (MFC). MFC is a bioelectrochemical system generated by bacterial metabolism that utilizes organic substrate. One of the substrates that can be used is whey, a waste generated from cheese production. Therefore, this study aimed to determine the power of potential current and voltage generated from the use of whey cheese as a substrate for bacterial metabolism. In this research, double chamber system was used in microbial fuel cell reactor by using cheese whey as substrate at anode and potassium permanganate as cathode and utilizing membrane nafion 212 as membrane of proton exchange. The variable of experiment was bacteria type. The types of bacteria used in this study were Lactobacillus bulgaricus, Streptococcus thermophillus and Lactobacillus casei. While the operating time used was 100 hours. The highest current produced was 74.6 μA and the highest voltage was 529.3 mV produced by Lactobacillus bulgaricus bacteria. In this study, it was also found that the death phase of the three bacteria was at 70-80 hours.

Double interconnection fuel cell array

DOEpatents

Draper, Robert; Zymboly, Gregory E.

1993-01-01

A fuel cell array (10) is made, containing number of tubular, elongated fuel cells (12) which are placed next to each other in rows (A, B, C, D), where each cell contains inner electrodes (14) and outer electrodes (18 and 18'), with solid electrolyte (16 and 16') between the electrodes, where the electrolyte and outer electrode are discontinuous, having two portions, and providing at least two opposed discontinuities which contain at least two oppositely opposed interconnections (20 and 20') contacting the inner electrode (14), each cell (12) having only three metallic felt electrical connectors (22) which contact surrounding cells, where each row is electrically connected to the other.

Simulation of the Formation of DNA Double Strand Breaks and Chromosome Aberrations in Irradiated Cells

NASA Technical Reports Server (NTRS)

Plante, Ianik; Ponomarev, Artem L.; Wu, Honglu; Blattnig, Steve; George, Kerry

2014-01-01

The formation of DNA double-strand breaks (DSBs) and chromosome aberrations is an important consequence of ionizing radiation. To simulate DNA double-strand breaks and the formation of chromosome aberrations, we have recently merged the codes RITRACKS (Relativistic Ion Tracks) and NASARTI (NASA Radiation Track Image). The program RITRACKS is a stochastic code developed to simulate detailed event-by-event radiation track structure: [1] This code is used to calculate the dose in voxels of 20 nm, in a volume containing simulated chromosomes, [2] The number of tracks in the volume is calculated for each simulation by sampling a Poisson distribution, with the distribution parameter obtained from the irradiation dose, ion type and energy. The program NASARTI generates the chromosomes present in a cell nucleus by random walks of 20 nm, corresponding to the size of the dose voxels, [3] The generated chromosomes are located within domains which may intertwine, and [4] Each segment of the random walks corresponds to approx. 2,000 DNA base pairs. NASARTI uses pre-calculated dose at each voxel to calculate the probability of DNA damage at each random walk segment. Using the location of double-strand breaks, possible rejoining between damaged segments is evaluated. This yields various types of chromosomes aberrations, including deletions, inversions, exchanges, etc. By performing the calculations using various types of radiations, it will be possible to obtain relative biological effectiveness (RBE) values for several types of chromosome aberrations.

Nanoneedle insertion into the cell nucleus does not induce double-strand breaks in chromosomal DNA.

PubMed

Ryu, Seunghwan; Kawamura, Ryuzo; Naka, Ryohei; Silberberg, Yaron R; Nakamura, Noriyuki; Nakamura, Chikashi

2013-09-01

An atomic force microscope probe can be formed into an ultra-sharp cylindrical shape (a nanoneedle) using micro-fabrication techniques such as focused ion beam etching. This nanoneedle can be effectively inserted through the plasma membrane of a living cell to not only access the cytosol, but also to penetrate through the nuclear membrane. This technique shows great potential as a tool for performing intranuclear measurements and manipulations. Repeated insertions of a nanoneedle into a live cell were previously shown not to affect cell viability. However, the effect of nanoneedle insertion on the nucleus and nuclear components is still unknown. DNA is the most crucial component of the nucleus for proper cell function and may be physically damaged by a nanoneedle. To investigate the integrity of DNA following nanoneedle insertion, the occurrence of DNA double-strand breaks (DSBs) was assessed. The results showed that there was no chromosomal DNA damage due to nanoneedle insertion into the nucleus, as indicated by the expression level of γ-H2AX, a molecular marker of DSBs. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Application of Lithium Attachment Mass Spectrometry for Knudsen Evaporation and Chemical Ionisation Mass Spectrometry (KEMS, CIMS)

NASA Astrophysics Data System (ADS)

Bannan, T.; Booth, M.; Benyezzar, M.; Bacak, A.; Alfarra, M. R. R.; Topping, D. O.; Percival, C.

2015-12-01

Lithium ion attachment mass spectrometry provides a non-specific, non-fragmenting and sensitive method for detection of volatile species in the gas phase. The design, manufacture, and results from lithium ion attachment ionisation sources for two mass spectrometry systems are presented. Trace gas analysis is investigated using a modified Chemical Ionization Mass Spectrometer (CIMS) and vapour pressure (VP) measurements using a modified Knudsen Effusion Mass Spectrometer (KEMS) are presented. The Li+ modified CIMS provided limits of detection of 4 ppt for acetone, 0.2 ppt for formic acid, 15 ppt for nitric acid and 120 ppt from ammonia. Despite improvements, the problem of burnout remained persistent. The Li+ CIMS would unlikely be suitable for field or aircraft work, but could be appropriate for certain lab applications. The KEMS currently utilizes an electron impact (EI) ionisation source which provides a highly sensitive source, with the drawback of fragmentation of ionized molecules (Booth et al., 2009). Using Li+ KEMS the VP of samples can be measured without fragmentation and can therefore be used to identify VPs of individual components in mixtures. The validity of using Li+ for determining the VP of mixtures was tested by making single component VP measurements, which showed good agreement with EI measurements of Poly ethylene glycol (PEG) 3 and PEG 4, both when individually measured and when mixed. The Li+ KEMS was then used to investigate a system of atmospheric relevance, α-pinene secondary organic aerosol, generated in a reaction chamber (Alfarra et al., 2012). The VPs of the individual components from this generated sample are within the range we expect for compounds capable of partitioning between the particle and gas phase of an aerosol (0.1-10-5 Pa). Li+ source has a calculated sensitivity approximately 75 times less than that of EI, but the lack of fragmentation using the Li+ source is a significant advantage.

Application of Lithium Attachment Mass Spectrometry for Knudsen Evaporation and Chemical Ionisation Mass Spectrometry (KEMS, CIMS)

NASA Astrophysics Data System (ADS)

Bannan, Thomas; Booth, A. Murray; Alfarra, Rami; Bacak, Asan; Pericval, Carl

2016-04-01

Lithium ion attachment mass spectrometry provides a non-specific, non-fragmenting and sensitive method for detection of volatile species in the gas phase. The design, manufacture, and results from lithium ion attachment ionisation sources for two mass spectrometry systems are presented. Trace gas analysis is investigated using a modified Chemical Ionization Mass Spectrometer (CIMS) and vapour pressure (VP) measurements using a modified Knudsen Effusion Mass Spectrometer (KEMS) are presented. The Li+ modified CIMS provided limits of detection of 4 ppt for acetone, 0.2 ppt for formic acid, 15 ppt for nitric acid and 120 ppt from ammonia. Despite improvements, the problem of burnout remained persistent. The Li+ CIMS would unlikely be suitable for field or aircraft work, but could be appropriate for certain lab applications. The KEMS currently utilizes an electron impact (EI) ionisation source which provides a highly sensitive source, with the drawback of fragmentation of ionized molecules (Booth et al., 2009). Using Li+ KEMS the VP of samples can be measured without fragmentation and can therefore be used to identify VPs of individual components in mixtures. The validity of using Li+ for determining the VP of mixtures was tested by making single component VP measurements, which showed good agreement with EI measurements of Poly ethylene glycol (PEG) 3 and PEG 4, both when individually measured and when mixed. The Li+ KEMS was then used to investigate a system of atmospheric relevance, α-pinene secondary organic aerosol, generated in a reaction chamber (Alfarra et al., 2012). The VPs of the individual components from this generated sample are within the range we expect for compounds capable of partitioning between the particle and gas phase of an aerosol (0.1-10-5 Pa). Li+ source has a calculated sensitivity approximately 75 times less than that of EI, but the lack of fragmentation using the Li+ source is a significant advantage.

Double overexpression of DREB and PIF transcription factors improves drought stress tolerance and cell elongation in transgenic plants.

PubMed

Kudo, Madoka; Kidokoro, Satoshi; Yoshida, Takuya; Mizoi, Junya; Todaka, Daisuke; Fernie, Alisdair R; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko

2017-04-01

Although a variety of transgenic plants that are tolerant to drought stress have been generated, many of these plants show growth retardation. To improve drought tolerance and plant growth, we applied a gene-stacking approach using two transcription factor genes: DEHYDRATION-RESPONSIVE ELEMENT-BINDING 1A (DREB1A) and rice PHYTOCHROME-INTERACTING FACTOR-LIKE 1 (OsPIL1). The overexpression of DREB1A has been reported to improve drought stress tolerance in various crops, although it also causes a severe dwarf phenotype. OsPIL1 is a rice homologue of Arabidopsis PHYTOCHROME-INTERACTING FACTOR 4 (PIF4), and it enhances cell elongation by activating cell wall-related gene expression. We found that the OsPIL1 protein was more stable than PIF4 under light conditions in Arabidopsis protoplasts. Transactivation analyses revealed that DREB1A and OsPIL1 did not negatively affect each other's transcriptional activities. The transgenic plants overexpressing both OsPIL1 and DREB1A showed the improved drought stress tolerance similar to that of DREB1A overexpressors. Furthermore, double overexpressors showed the enhanced hypocotyl elongation and floral induction compared with the DREB1A overexpressors. Metabolome analyses indicated that compatible solutes, such as sugars and amino acids, accumulated in the double overexpressors, which was similar to the observations of the DREB1A overexpressors. Transcriptome analyses showed an increased expression of abiotic stress-inducible DREB1A downstream genes and cell elongation-related OsPIL1 downstream genes in the double overexpressors, which suggests that these two transcription factors function independently in the transgenic plants despite the trade-offs required to balance plant growth and stress tolerance. Our study provides a basis for plant genetic engineering designed to overcome growth retardation in drought-tolerant transgenic plants. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology

Dynamic dependence on ATR and ATM for double-strand break repair in human embryonic stem cells and neural descendants.

PubMed

Adams, Bret R; Golding, Sarah E; Rao, Raj R; Valerie, Kristoffer

2010-04-02

The DNA double-strand break (DSB) is the most toxic form of DNA damage. Studies aimed at characterizing DNA repair during development suggest that homologous recombination repair (HRR) is more critical in pluripotent cells compared to differentiated somatic cells in which nonhomologous end joining (NHEJ) is dominant. We have characterized the DNA damage response (DDR) and quality of DNA double-strand break (DSB) repair in human embryonic stem cells (hESCs), and in vitro-derived neural cells. Resolution of ionizing radiation-induced foci (IRIF) was used as a surrogate for DSB repair. The resolution of gamma-H2AX foci occurred at a slower rate in hESCs compared to neural progenitors (NPs) and astrocytes perhaps reflective of more complex DSB repair in hESCs. In addition, the resolution of RAD51 foci, indicative of active homologous recombination repair (HRR), showed that hESCs as well as NPs have high capacity for HRR, whereas astrocytes do not. Importantly, the ATM kinase was shown to be critical for foci formation in astrocytes, but not in hESCs, suggesting that the DDR is different in these cells. Blocking the ATM kinase in astrocytes not only prevented the formation but also completely disassembled preformed repair foci. The ability of hESCs to form IRIF was abrogated with caffeine and siRNAs targeted against ATR, implicating that hESCs rely on ATR, rather than ATM for regulating DSB repair. This relationship dynamically changed as cells differentiated. Interestingly, while the inhibition of the DNA-PKcs kinase (and presumably non-homologous endjoining [NHEJ]) in astrocytes slowed IRIF resolution it did not in hESCs, suggesting that repair in hESCs does not utilize DNA-PKcs. Altogether, our results show that hESCs have efficient DSB repair that is largely ATR-dependent HRR, whereas astrocytes critically depend on ATM for NHEJ, which, in part, is DNA-PKcs-independent.

Innovative Microcapsules for Pancreatic β-Cells Harvested from Mature Double-Transgenic Mice: Cell Imaging, Viability, Induced Glucose-Stimulated Insulin Measurements and Proinflammatory Cytokines Analysis.

PubMed

Mooranian, Armin; Tackechi, Ryu; Jamieson, Emma; Morahan, Grant; Al-Salami, Hani

2017-06-01

Recently we demonstrated that microencapsulation of a murine pancreatic β-cell line using an alginate-ursodeoxycholic acid (UDCA) matrix produced microcapsules with good stability and cell viability. In this study, we investigated if translation of this formulation to microencapsulation of primary β-cells harvested from mature double-transgenic healthy mice would also generate stable microcapsules with good cell viability. Islets of Langerhans were isolated from Ngn3-GFP/RIP-DsRED mice by intraductal collagenase P digestion and density gradient centrifugation, dissociated into single cells and the β-cell population purified by Fluorescence Activated Cell Sorting. β-cells were microencapsulated using either alginate-poly-l-ornithine (F1; control) or alginate-poly-l-ornithine-UDCA (F2; test) formulations. Microcapsules were microscopically examined and microencapsulated cells were analyzed for viability, insulin and cytokine release, 2 days post-microencapsulation. Microcapsules showed good uniformity and morphological characteristics and even cell distribution within microcapsules with or without UDCA. Two days post microencapsulation cell viability, mitochondrial ATP and insulin production were shown to be optimized in the presence of UDCA whilst production of the proinflammatory cytokine IL-1β was reduced. Contradictory to our previous studies, UDCA did not reduce production of any other pro-inflammatory biomarkers. These results suggest that UDCA incorporation improves microcapsules' physical and morphological characteristics and improves the viability and function of encapsulated mature primary pancreatic β-cells.

Can Pb-Free Halide Double Perovskites Support High-Efficiency Solar Cells?

PubMed Central

2016-01-01

The methylammonium lead halides have become champion photoactive semiconductors for solar cell applications; however, issues still remain with respect to chemical instability and potential toxicity. Recently, the Cs2AgBiX6 (X = Cl, Br) double perovskite family has been synthesized and investigated as stable nontoxic replacements. We probe the chemical bonding, physical properties, and cation anti-site disorder of Cs2AgBiX6 and related compounds from first-principles. We demonstrate that the combination of Ag(I) and Bi(III) leads to the wide indirect band gaps with large carrier effective masses owing to a mismatch in angular momentum of the frontier atomic orbitals. The spectroscopically limited photovoltaic conversion efficiency is less than 10% for X = Cl or Br. This limitation can be overcome by replacing Ag with In or Tl; however, the resulting compounds are predicted to be unstable thermodynamically. The search for nontoxic bismuth perovskites must expand beyond the Cs2AgBiX6 motif. PMID:28066823

Can Pb-Free Halide Double Perovskites Support High-Efficiency Solar Cells?

PubMed

Savory, Christopher N; Walsh, Aron; Scanlon, David O

2016-11-11

The methylammonium lead halides have become champion photoactive semiconductors for solar cell applications; however, issues still remain with respect to chemical instability and potential toxicity. Recently, the Cs 2 AgBiX 6 (X = Cl, Br) double perovskite family has been synthesized and investigated as stable nontoxic replacements. We probe the chemical bonding, physical properties, and cation anti-site disorder of Cs 2 AgBiX 6 and related compounds from first-principles. We demonstrate that the combination of Ag(I) and Bi(III) leads to the wide indirect band gaps with large carrier effective masses owing to a mismatch in angular momentum of the frontier atomic orbitals. The spectroscopically limited photovoltaic conversion efficiency is less than 10% for X = Cl or Br. This limitation can be overcome by replacing Ag with In or Tl; however, the resulting compounds are predicted to be unstable thermodynamically. The search for nontoxic bismuth perovskites must expand beyond the Cs 2 AgBiX 6 motif.

Ion-kinetic simulations of D- 3He gas-filled inertial confinement fusion target implosions with moderate to large Knudsen number

DOE PAGES

Larroche, O.; Rinderknecht, H. G.; Rosenberg, M. J.; ...

2016-01-06

Experiments designed to investigate the transition to non-collisional behavior in D 3He-gas inertial confinement fusion target implosions display increasingly large discrepancies with respect to simulations by standard hydrodynamics codes as the expected ion mean-free-paths λ c increase with respect to the target radius R (i.e., when the Knudsen number N K = λ c/R grows). To take properly into account large N K's, multi-ion-species Vlasov-Fokker-Planck computations of the inner gas in the capsules have been performed, for two different values of N K, one moderate and one large. The results, including nuclear yield, reactivity-weighted ion temperatures, nuclear emissivities, and surfacemore » brightness, have been compared with the experimental data and with the results of hydrodynamical simulations, some of which include an ad hocmodeling of kinetic effects. The experimental results are quite accurately rendered by the kinetic calculations in the smaller-N K case, much better than by the hydrodynamical calculations. The kinetic effects at play in this case are thus correctly understood. However, in the higher-N K case, the agreement is much worse. Furthermore, the remaining discrepancies are shown to arise from kinetic phenomena (e.g., inter-species diffusion) occurring at the gas-pusher interface, which should be investigated in the future work.« less

The fabrication of a double-layer atom chip with through silicon vias for an ultra-high-vacuum cell

NASA Astrophysics Data System (ADS)

Chuang, Ho-Chiao; Lin, Yun-Siang; Lin, Yu-Hsin; Huang, Chi-Sheng

2014-04-01

This study presents a double-layer atom chip that provides users with increased diversity in the design of the wire patterns and flexibility in the design of the magnetic field. It is more convenient for use in atomic physics experiments. A negative photoresist, SU-8, was used as the insulating layer between the upper and bottom copper wires. The electrical measurement results show that the upper and bottom wires with a width of 100 µm can sustain a 6 A current without burnout. Another focus of this study is the double-layer atom chips integrated with the through silicon via (TSV) technique, and anodically bonded to a Pyrex glass cell, which makes it a desired vacuum chamber for atomic physics experiments. Thus, the bonded glass cell not only significantly reduces the overall size of the ultra-high-vacuum (UHV) chamber but also conducts the high current from the backside to the front side of the atom chip via the TSV under UHV (9.5 × 10-10 Torr). The TSVs with a diameter of 70 µm were etched through by the inductively coupled plasma ion etching and filled by the bottom-up copper electroplating method. During the anodic bonding process, the electroplated copper wires and TSVs on atom chips also need to pass the examination of the required bonding temperature of 250 °C, under an applied voltage of 1000 V. Finally, the UHV test of the double-layer atom chips with TSVs at room temperature can be reached at 9.5 × 10-10 Torr, thus satisfying the requirements of atomic physics experiments under an UHV environment.

Mushroom acidic glycosphingolipid induction of cytokine secretion from murine T cells and proliferation of NK1.1 {alpha}/{beta} TCR-double positive cells in vitro

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nozaki, Hirofumi; Itonori, Saki; Sugita, Mutsumi

2008-08-29

Interferon (IFN)-{gamma} and interleukin (IL)-4 regulate many types of immune responses. Here we report that acidic glycosphingolipids (AGLs) of Hypsizigus marmoreus and Pleurotus eryngii induced secretion of IFN- {gamma} and IL-4 from T cells in a CD11c-positive cell-dependent manner similar to that of {alpha}-galactosylceramide ({alpha}-GalCer) and isoglobotriaosylceramide (iGb3), although activated T cells by AGLs showed less secretion of cytokine than those activated by {alpha}-GalCer. In addition, stimulation of these mushroom AGLs induced proliferation of NK1.1 {alpha}/{beta} TCR-double positive cells in splenocytes. Administration of a mixture of {alpha}-GalCer and AGLs affected the stimulation of {alpha}-GalCer and generally induced a subtle Th1more » bias for splenocytes but induced an extreme Th2 bias for thymocytes. These results suggested that edible mushroom AGLs contribute to immunomodulation.« less

Double hard scattering without double counting

NASA Astrophysics Data System (ADS)

Diehl, Markus; Gaunt, Jonathan R.; Schönwald, Kay

2017-06-01

Double parton scattering in proton-proton collisions includes kinematic regions in which two partons inside a proton originate from the perturbative splitting of a single parton. This leads to a double counting problem between single and double hard scattering. We present a solution to this problem, which allows for the definition of double parton distributions as operator matrix elements in a proton, and which can be used at higher orders in perturbation theory. We show how the evaluation of double hard scattering in this framework can provide a rough estimate for the size of the higher-order contributions to single hard scattering that are affected by double counting. In a numeric study, we identify situations in which these higher-order contributions must be explicitly calculated and included if one wants to attain an accuracy at which double hard scattering becomes relevant, and other situations where such contributions may be neglected.

Quantitative, non-invasive imaging of radiation-induced DNA double strand breaks in vivo

PubMed Central

Li, Wenrong; Li, Fang; Huang, Qian; Shen, Jingping; Wolf, Frank; He, Yujun; Liu, Xinjian; Hu, Y. Angela; Bedford, Joel. S.; Li, Chuan-Yuan

2011-01-01

DNA double strand breaks is a major form of DNA damage and a key mechanism through which radiotherapy and some chemotherapeutic agents kill cancer cells. Despite its importance, measuring DNA double strand breaks is still a tedious task that is normally carried out by gel electrophoresis or immunofluorescence staining. Here we report a novel approach to image and quantify DNA double strand breaks in live mammalian cells through bi-fragment luciferase reconstitution. N- and C- terminal fragments of firefly luciferase gene were fused with H2AX and MDC1 genes, respectively. Our strategy was based on the established fact that at the sites of DNA double strand breaks, H2AX protein is phosphoryated and physically associates with the MDC1 protein, thus bringing together N- and C- luciferase fragments and reconstituting luciferase activity. Our strategy allowed serial, non-invasive quantification of DNA double strand breaks in cells irradiated with x-rays and 56Fe ions. Furthermore, it allowed for the evaluation of DNA double strand breaks (DSBs) non-invasively in vivo in irradiated tumors over two weeks. Surprisingly, we detected a second wave of DSB induction in irradiated tumor cells days after radiation exposure in addition to the initial rapid induction of DSBs. We conclude that our new split-luciferase based method for imaging γ-H2AX-MDC1 interaction is a powerful new tool to study DNA double strand break repair kinetics in vivo with considerable advantage for experiments requiring observations over an extended period of time. PMID:21527553

Efficient repair of DNA double-strand breaks in malignant cells with structural instability

PubMed Central

Cheng, Yue; Zhang, Zhenhua; Keenan, Bridget; Roschke, Anna V.; Nakahara, Kenneth; Aplan, Peter D.

2009-01-01

Aberrant repair of DNA double strand breaks (DSBs) is thought to be important in the generation of gross chromosomal rearrangements (GCRs). To examine how DNA DSBs might lead to GCRs, we investigated the repair of a single DNA DSB in a structurally unstable cell line. An I-SceI recognition site was introduced into OVCAR-8 cells between a constitutive promoter (EF1α) and the Herpes simplex virus thymidine kinase (TK) gene, which confers sensitivity to gancyclovir (GCV). Expression of I-SceI in these cells caused a single DSB. Clones with aberrant repair could acquire resistance to GCV by separation of the EF1α promoter from the TK gene, or deletion of either the EF1α promoter or the TK gene. All mutations that we identified were interstitial deletions. Treatment of cells with etoposide or bleomycin, agents known to produce DNA DSBs following expression of I-SceI also did not generate GCRs. Because we identified solely interstitial deletions using the aforementioned negative selection system, we developed a positive selection system to produce GCR. A construct containing an I-SceI restriction site immediately followed by a hygromycin phosphotransferase cDNA, with no promoter, was stably integrated into OVCAR-8 cells. DNA DSBs were produced by an I-SceI expression vector. None of the hygromycin resistant clones recovered had linked the hygromycin phosphotransferase cDNA to an endogenous promoter, but had instead captured a portion of the I-SceI expression vector. These results indicate that even in a structurally unstable malignant cell line, the majority of DNA DSBs are repaired by religation of the two broken chromosome ends, without the introduction of a GCR. PMID:19909760

Efficient repair of DNA double-strand breaks in malignant cells with structural instability.

PubMed

Cheng, Yue; Zhang, Zhenhua; Keenan, Bridget; Roschke, Anna V; Nakahara, Kenneth; Aplan, Peter D

2010-01-05

Aberrant repair of DNA double-strand breaks (DSBs) is thought to be important in the generation of gross chromosomal rearrangements (GCRs). To examine how DNA DSBs might lead to GCRs, we investigated the repair of a single DNA DSB in a structurally unstable cell line. An I-SceI recognition site was introduced into OVCAR-8 cells between a constitutive promoter (EF1alpha) and the Herpes simplex virus thymidine kinase (TK) gene, which confers sensitivity to gancyclovir (GCV). Expression of I-SceI in these cells caused a single DSB. Clones with aberrant repair could acquire resistance to GCV by separation of the EF1alpha promoter from the TK gene, or deletion of either the EF1alpha promoter or the TK gene. All mutations that we identified were interstitial deletions. Treatment of cells with etoposide or bleomycin, agents known to produce DNA DSBs following expression of I-SceI also did not generate GCRs. Because we identified solely interstitial deletions using the aforementioned negative selection system, we developed a positive selection system to produce GCR. A construct containing an I-SceI restriction site immediately followed by a hygromycin phosphotransferase cDNA, with no promoter, was stably integrated into OVCAR-8 cells. DNA DSBs were produced by an I-SceI expression vector. None of the hygromycin resistant clones recovered had linked the hygromycin phosphotransferase cDNA to an endogenous promoter, but had instead captured a portion of the I-SceI expression vector. These results indicate that even in a structurally unstable malignant cell line, the majority of DNA DSBs are repaired by religation of the two broken chromosome ends, without the introduction of a GCR.

Enhancement of expression of survivin promoter-driven CD/TK double suicide genes by the nuclear matrix attachment region in transgenic gastric cancer cells.

PubMed

Niu, Ying; Li, Jian-Sheng; Luo, Xian-Run

2014-01-25

This work aimed to study a novel transgenic expression system of the CD/TK double suicide genes enhanced by the nuclear matrix attachment region (MAR) for gene therapy. The recombinant vector pMS-CD/TK containing the MAR-survivin promoter-CD/TK cassette was developed and transfected into human gastric cancer SGC-7901 cells. Expression of the CD/TK genes was detected by quantitative real-time PCR (qPCR) and Western blot. Cell viability and apoptosis were measured using the methyl thiazolyl tetrazolium (MTT) assay and flow cytometry. When the MAR fragment was inserted into the upstream of the survivin promoter, the qPCR result showed that the expression of the CD/TK genes significantly increased 7.7-fold in the transgenic SGC-7901 cells with plasmid pMS-CD/TK compared with that without MAR. MTT and flow cytometry analyses indicated that treatment with the prodrugs (5-FC+GCV) significantly decreased the cellular survival rate and enhanced the cellular apoptosis in the SGC-7901 cells. The expression of the CD/TK double suicide genes driven by the survivin promoter can be enhanced by the MAR fragment in human gastric cancer cells. Copyright © 2013 Elsevier B.V. All rights reserved.

S-layer and cytoplasmic membrane - exceptions from the typical archaeal cell wall with a focus on double membranes.

PubMed

Klingl, Andreas

2014-01-01

The common idea of typical cell wall architecture in archaea consists of a pseudo-crystalline proteinaceous surface layer (S-layer), situated upon the cytoplasmic membrane. This is true for the majority of described archaea, hitherto. Within the crenarchaea, the S-layer often represents the only cell wall component, but there are various exceptions from this wall architecture. Beside (glycosylated) S-layers in (hyper)thermophilic cren- and euryarchaea as well as halophilic archaea, one can find a great variety of other cell wall structures like proteoglycan-like S-layers (Halobacteria), glutaminylglycan (Natronococci), methanochondroitin (Methanosarcina) or double layered cell walls with pseudomurein (Methanothermus and Methanopyrus). The presence of an outermost cellular membrane in the crenarchaeal species Ignicoccus hospitalis already gave indications for an outer membrane similar to Gram-negative bacteria. Although there is just limited data concerning their biochemistry and ultrastructure, recent studies on the euryarchaeal methanogen Methanomassiliicoccus luminyensis, cells of the ARMAN group, and the SM1 euryarchaeon delivered further examples for this exceptional cell envelope type consisting of two membranes.

Intestinal double-positive CD4+CD8+ T cells of neonatal rhesus macaques are proliferating, activated memory cells and primary targets for SIVMAC251 infection

PubMed Central

Wang, Xiaolei; Das, Arpita; Lackner, Andrew A.; Veazey, Ronald S.

2008-01-01

Peripheral blood and thymic double-positive (DP) CD4+CD8+ T cells from neonates have been described earlier, but the function and immunophenotypic characteristics of other tissue-derived DP T cells are not clearly understood. Here, we demonstrate the functional and immunophenotypic characteristics of DP cells in 6 different tissues, including thymus from normal neonatal rhesus macaques (Macaca mulatta) between 0 and 21 days of age. In general, intestinal DP T cells of neonates have higher percentages of memory markers (CD28+CD95+CD45RAlowCD62Llow) and proliferation compared with single-positive (SP) CD4+ and CD8+ T cells. In addition, percentages of DP T cells increase and CD62L expression decreases as animals mature, suggesting that DP cells mature and proliferate with maturity and/or antigen exposure. Consistent with this, intestinal DP T cells in neonates express higher levels of CCR5 and are the primary targets in simian immunodeficiency virus (SIV) infection. Finally, DP T cells produce higher levels of cytokine in response to mitogen stimulation compared with SP CD4+ or CD8+ T cells. Collectively, these findings demonstrate that intestinal DP T cells of neonates are proliferating, activated memory cells and are likely involved in regulating immune responses, in contrast to immature DP T cells in the thymus. PMID:18820133

Transcription-associated processes cause DNA double-strand breaks and translocations in neural stem/progenitor cells.

PubMed

Schwer, Bjoern; Wei, Pei-Chi; Chang, Amelia N; Kao, Jennifer; Du, Zhou; Meyers, Robin M; Alt, Frederick W

2016-02-23

High-throughput, genome-wide translocation sequencing (HTGTS) studies of activated B cells have revealed that DNA double-strand breaks (DSBs) capable of translocating to defined bait DSBs are enriched around the transcription start sites (TSSs) of active genes. We used the HTGTS approach to investigate whether a similar phenomenon occurs in primary neural stem/progenitor cells (NSPCs). We report that breakpoint junctions indeed are enriched around TSSs that were determined to be active by global run-on sequencing analyses of NSPCs. Comparative analyses of transcription profiles in NSPCs and B cells revealed that the great majority of TSS-proximal junctions occurred in genes commonly expressed in both cell types, possibly because this common set has higher transcription levels on average than genes transcribed in only one or the other cell type. In the latter context, among all actively transcribed genes containing translocation junctions in NSPCs, those with junctions located within 2 kb of the TSS show a significantly higher transcription rate on average than genes with junctions in the gene body located at distances greater than 2 kb from the TSS. Finally, analysis of repair junction signatures of TSS-associated translocations in wild-type versus classical nonhomologous end-joining (C-NHEJ)-deficient NSPCs reveals that both C-NHEJ and alternative end-joining pathways can generate translocations by joining TSS-proximal DSBs to DSBs on other chromosomes. Our studies show that the generation of transcription-associated DSBs is conserved across divergent cell types.

Double layered tailorable advanced blanket insulation

NASA Technical Reports Server (NTRS)

Falstrup, D.

1983-01-01

An advanced flexible reusable surface insulation material for future space shuttle flights was investigated. A conventional fly shuttle loom with special modifications to weave an integral double layer triangular core fabric from quartz yarn was used. Two types of insulating material were inserted into the cells of the fabric, and a procedure to accomplish this was developed. The program is follow up of a program in which single layer rectangular cell core fabrics are woven and a single type of insulating material was inserted into the cells.

Double minute chromosomes in mouse methotrexate-resistant cells studied by atomic force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng Xinyu; Zhang Liangyu; Zhang Yu

2006-08-11

Double minute chromosomes (DMs) are acentric, autonomously replicating extra-chromosomes and frequently mediate gene amplification in tumor and drug resistant cells. Atomic force microscopy (AFM) is a powerful tool in microbiology. We used AFM to explore the ultrastructure of DMs in mouse fibroblasts 3T3R500. DMs in various phases of cell cycle were also studied in order to elucidate the mechanisms of their duplication and separation. Metaphase spread and induced premature condensed chromosomes (PCCs) were observed under the AFM. DMs were detected to be composed of two compact spheres linked by fibers. The fibers of DMs directly connected with metaphase chromosomes weremore » observed. Many single-minutes and few DMs were detected in G1 PCCs, while more DMs were detected in S PCCs than in G1 PCCs. Besides, all of the DMs in G2 PCCs were coupled. Our present results suggested that DMs might divide into single-minutes during or before G1-phase, followed by duplication of the single-minutes in S-phase. Moreover, we introduced a new powerful tool to study DMs and got some ideal results.« less

The Electrical Double Layer and Its Structure

NASA Astrophysics Data System (ADS)

Stojek, Zbigniew

At any electrode immersed in an electrolyte solution, a specific interfacial region is formed. This region is called the double layer. The electrical properties of such a layer are important, since they significantly affect the electrochemical measurements. In an electrical circuit used to measure the current that flows at a particular working electrode, the double layer can be viewed as a capacitor. Figure I.1.1 depicts this situation where the electrochemical cell is represented by an electrical circuit and capacitor C d corresponds to the differential capacity of the double layer. To obtain a desired potential at the working electrodes, the double-layer capacitor must be first appropriately charged, which means that a capacitive current, not related to the reduction or oxidation of the substrates, flows in the electrical circuit. While this capacitive current carries some information concerning the double layer and its structure, and in some cases can be used for analytical purposes, in general, it interferes with electrochemical investigations. A variety of methods are used in electrochemistry to depress, isolate, or filter the capacitive current.

Measuring electrical and mechanical properties of red blood cells with a double optical tweezers

NASA Astrophysics Data System (ADS)

Fontes, Adriana; Fernandes, Heloise P.; Barjas-Castro, Maria L.; de Thomaz, André A.; Pozzo, Liliana d. Y.; Barbosa, Luiz C.; Cesar, Carlos L.

2006-08-01

The fluid lipid bilayer viscoelastic membrane of red blood cells (RBC) contains antigen glycolproteins and proteins which can interact with antibodies to cause cell agglutination. This is the basis of most of the immunohematologic tests in blood banks and the identification of the antibodies against the erythrocyte antigens is of fundamental importance for transfusional routines. The negative charges of the RBCs creates a repulsive electric (zeta) potential between the cells and prevents their aggregation in the blood stream. The first counterions cloud strongly binded moving together with the RBC is called the compact layer. This report proposes the use of a double optical tweezers for a new procedure for measuring: (1) the apparent membrane viscosity, (2) the cell adhesion, (3) the zeta potential and (4) the compact layer's size of the charges formed around the cell in the electrolytic solution. To measure the membrane viscosity we trapped silica beads strongly attached to agglutinated RBCs and measured the force to slide one RBC over the other as a function of the relative velocity. The RBC adhesion was measured by slowly displacing two RBCs apart until the disagglutination happens. The compact layer's size was measured using the force on the silica bead attached to a single RBC in response to an applied voltage and the zeta potential was obtained by measuring the terminal velocity after releasing the RBC from the optical trap at the last applied voltage. We believe that the methodology here proposed can improve the methods of diagnosis in blood banks.

BRCA2 and RAD51 promote double-strand break formation and cell death in response to gemcitabine.

PubMed

Jones, Rebecca M; Kotsantis, Panagiotis; Stewart, Grant S; Groth, Petra; Petermann, Eva

2014-10-01

Replication inhibitors cause replication fork stalling and double-strand breaks (DSB) that result from processing of stalled forks. During recovery from replication blocks, the homologous recombination (HR) factor RAD51 mediates fork restart and DSB repair. HR defects therefore sensitize cells to replication inhibitors, with clear implications for cancer therapy. Gemcitabine is a potent replication inhibitor used to treat cancers with mutations in HR genes such as BRCA2. Here, we investigate why, paradoxically, mutations in HR genes protect cells from killing by gemcitabine. Using DNA replication and DNA damage assays in mammalian cells, we show that even short gemcitabine treatments cause persistent replication inhibition. BRCA2 and RAD51 are recruited to chromatin early after removal of the drug, actively inhibit replication fork progression, and promote the formation of MUS81- and XPF-dependent DSBs that remain unrepaired. Our data suggest that HR intermediates formed at gemcitabine-stalled forks are converted into DSBs and thus contribute to gemcitabine-induced cell death, which could have implications for the treatment response of HR-deficient tumors. ©2014 American Association for Cancer Research.

BRCA2 and RAD51 promote double-strand break formation and cell death in response to Gemcitabine

PubMed Central

Jones, Rebecca M.; Kotsantis, Panagiotis; Stewart, Grant S.; Groth, Petra; Petermann, Eva

2014-01-01

Replication inhibitors cause replication fork stalling and double-strand breaks (DSBs) that result from processing of stalled forks. During recovery from replication blocks, the homologous recombination (HR) factor RAD51 mediates fork restart and DSB repair. HR defects therefore sensitise cells to replication inhibitors, with clear implications for cancer therapy. Gemcitabine is a potent replication inhibitor used to treat cancers with mutations in HR genes such as BRCA2. Here we investigate why, paradoxically, mutations in HR genes protect cells from killing by Gemcitabine. Using DNA replication and -damage assays in mammalian cells, we show that even short Gemcitabine treatments cause persistent replication inhibition. BRCA2 and RAD51 are recruited to chromatin early after removal of the drug, actively inhibit replication fork progression and promote the formation of MUS81- and XPF-dependent DSBs that remain unrepaired. Our data suggest that HR intermediates formed at Gemcitabine-stalled forks are converted into DSBs and thus contribute to Gemcitabine-induced cell death, which could have implications for the treatment response of HR-deficient tumours. PMID:25053826

Mechanisms of β-Cell Death in Response to Double-Stranded (ds) RNA and Interferon-γ

PubMed Central

Scarim, Anna L.; Arnush, Marc; Blair, Libby A.; Concepcion, Josephine; Heitmeier, Monique R.; Scheuner, Donalyn; Kaufman, Randal J.; Ryerse, Jan; Buller, R. Mark; Corbett, John A.

2001-01-01

Viral infection is one environmental factor that has been implicated as a precipitating event that may initiate β-cell damage during the development of diabetes. This study examines the mechanisms by which the viral replicative intermediate, double-stranded (ds) RNA impairs β-cell function and induces β-cell death. The synthetic dsRNA molecule polyinosinic-polycytidylic acid (poly IC) stimulates β-cell DNA damage and apoptosis without impairing islet secretory function. In contrast, the combination of poly IC and interferon (IFN)-γ stimulates DNA damage, apoptosis, and necrosis of islet cells, and this damage is associated with the inhibition of glucose-stimulated insulin secretion. Nitric oxide mediates the inhibitory and destructive actions of poly IC + IFN-γ on insulin secretion and islet cell necrosis. Inhibitors of nitric oxide synthase, aminoguanidine, and NG-monomethyl-l-arginine, attenuate poly IC + IFN-γ-induced DNA damage to levels observed in response to poly IC alone, prevent islet cell necrosis, and prevent the inhibitory actions on glucose-stimulated insulin secretion. NG-monomethyl-l-arginine fails to prevent poly IC- and poly IC + IFN-γ-induced islet cell apoptosis. PKR, the dsRNA-dependent protein kinase that mediates the antiviral response in infected cells, is required for poly IC- and poly IC + IFN-γ-induced islet cell apoptosis, but not nitric oxide-mediated islet cell necrosis. Alone, poly IC fails to stimulate DNA damage in islets isolated from PKR-deficient mice; however, nitric oxide-dependent DNA damage induced by the combination of poly IC + IFN-γ is not attenuated by the genetic absence of PKR. These findings indicate that dsRNA stimulates PKR-dependent islet cell apoptosis, an event that is associated with normal islet secretory function. In contrast, poly IC + IFN-γ-induced inhibition of glucose-stimulated insulin secretion and islet cell necrosis are events that are mediated by islet production of nitric oxide. These

A prospective, randomized, double-blind study, comparing unirradiated to irradiated white blood cell transfusions in acute leukemia patients

PubMed Central

Freireich, E J; Lichtiger, B; Mattiuzzi, G; Martinez, F; Reddy, V; Kyle Wathen, J

2013-01-01

A prospective, randomized double-blind study comparing the effects of irradiated and unirradiated white blood cells was conducted in 108 acute leukemia patients with life-threatening infections, refractory to antibiotics. The study demonstrated no significant improvement in 30-day survival or overall survival. Transfusion of unirradiated white cells did not compromise the patient's opportunity to undergo allogeneic stem cell transplant, nor the success rate or overall survival after allogeneic transplant. The important positive finding in this study was that the unirradiated white cells produced a significantly higher increment in circulating granulocytes and in a higher proportion of patients granulocyte count exceeded 1000 per microliter, approaching normal concentrations. The increase in the number and the improved survival of the unirradiated granulocytes suggest that this procedure might potentially be a method to improve the utility of granulocyte transfusions and merits further investigation. The study demonstrated non-inferiority for unirradiated white cells. There were no harmful effects such as graft-versus-host disease, indicating that such studies would be safe to conduct in the future. PMID:23072780

High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter.

PubMed

Kim, Jeehwan; Hiroi, Homare; Todorov, Teodor K; Gunawan, Oki; Kuwahara, Masaru; Gokmen, Tayfun; Nair, Dhruv; Hopstaken, Marinus; Shin, Byungha; Lee, Yun Seog; Wang, Wei; Sugimoto, Hiroki; Mitzi, David B

2014-11-26

High-efficiency Cu2ZnSn(S,Se)4 solar cells are reported by applying In2S3/CdS double emitters. This new structure offers a high doping concentration within the Cu2ZnSn(S,Se)4 solar cells, resulting in a substantial enhancement in open-circuit voltage. The 12.4% device is obtained with a record open-circuit voltage deficit of 593 mV. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oilseed rape seeds with ablated defence cells of the glucosinolate–myrosinase system. Production and characteristics of double haploid MINELESS plants of Brassica napus L.

PubMed Central

Ahuja, Ishita; Borgen, Birgit Hafeld; Hansen, Magnor; Honne, Bjørn Ivar; Müller, Caroline; Rohloff, Jens; Rossiter, John Trevor; Bones, Atle Magnar

2011-01-01

Oilseed rape and other crop plants of the family Brassicaceae contain a unique defence system known as the glucosinolate–myrosinase system or the ‘mustard oil bomb’. The ‘mustard oil bomb’ which includes myrosinase and glucosinolates is triggered by abiotic and biotic stress, resulting in the formation of toxic products such as nitriles and isothiocyanates. Myrosinase is present in specialist cells known as ‘myrosin cells’ and can also be known as toxic mines. The myrosin cell idioblasts of Brassica napus were genetically reprogrammed to undergo controlled cell death (ablation) during seed development. These myrosin cell-free plants have been named MINELESS as they lack toxic mines. This has led to the production of oilseed rape with a significant reduction both in myrosinase levels and in the hydrolysis of glucosinolates. Even though the myrosinase activity in MINELESS was very low compared with the wild type, variation was observed. This variability was overcome by producing homozygous seeds. A microspore culture technique involving non-fertile haploid MINELESS plants was developed and these plants were treated with colchicine to produce double haploid MINELESS plants with full fertility. Double haploid MINELESS plants had significantly reduced myrosinase levels and glucosinolate hydrolysis products. Wild-type and MINELESS plants exhibited significant differences in growth parameters such as plant height, leaf traits, matter accumulation, and yield parameters. The growth and developmental pattern of MINELESS plants was relatively slow compared with the wild type. The characteristics of the pure double haploid MINELESS plant are described and its importance for future biochemical, agricultural, dietary, functional genomics, and plant defence studies is discussed. PMID:21778185

Double sex and mab-3 related transcription factor 1 regulates differentiation and proliferation in dairy goat male germline stem cells.

PubMed

Wei, Yudong; Cai, Shufang; Ma, Fanglin; Zhang, Ying; Zhou, Zhe; Xu, Shuanshuan; Zhang, Mengfei; Peng, Sha; Hua, Jinlian

2018-03-01

The protein encoded by double sex and mab-3 related transcription factor 1 (Dmrt1) gene contains a double sex/mab-3 domain, which was considered as one of the most conservative structures in sex determination. However, its effect on spermatogenesis of dairy goat spermatogonial stem cells (SSCs) remains to be clarified. For the first time, the roles of Dmrt1 in spermatogenesis of livestock are highlighted. Here, we investigated the expression pattern of Dmrt1 in the testes of dairy goats. Dmrt1 primarily located in undifferentiated SSCs. Moreover, Dmrt1 enhanced differentiation and proliferation of mGSCs. On the contrary, the level of meiosis was down-regulated, as Dmrt1 determines whether SSCs undergo mitosis and spermatogonial differentiation or meiosis. In the busulfan-treated mice testes, Dmrt1 repair germ cell damage was emphasized as well. Our results exposed that Dmrt1 maintenance mGSCs in two ways: facilitating proliferation and self-renewal of SSCs; and reducing the inflammatory response caused by reproductive injury. These findings identify a central role for Dmrt1 in controlling population stability and injury restoring of SSCs. © 2017 Wiley Periodicals, Inc.

Pressure, stress, and strain distribution in the double-stage diamond anvil cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lobanov, Sergey S., E-mail: slobanov@carnegiescience.edu; V.S. Sobolev Institute of Geology and Mineralogy SB RAS, Novosibirsk 630090; Prakapenka, Vitali B.

Double stage diamond anvil cells (DACs) of two designs have been assembled and tested. We used a standard symmetric DAC with flat or beveled culets as a primary stage and CVD microanvils machined by a focused ion beam as a second. We evaluated pressure, stress, and strain distributions in gold and a mixture of gold and iron as well as in secondary anvils using synchrotron x-ray diffraction with a micro-focused beam. A maximum pressure of 240 GPa was reached independent of the first stage anvil culet size. We found that the stress field generated by the second stage anvils is typicalmore » of conventional DAC experiments. The maximum pressures reached are limited by strains developing in the secondary anvil and by cupping of the first stage diamond anvil in the presented experimental designs. Also, our experiments show that pressures of several megabars may be reached without sacrificing the first stage diamond anvils.« less

The double layers in the plasma sheet boundary layer during magnetic reconnection

NASA Astrophysics Data System (ADS)

Guo, J.; Yu, B.

2014-11-01

We studied the evolutions of double layers which appear after the magnetic reconnection through two-dimensional electromagnetic particle-in-cell simulation. The simulation results show that the double layers are formed in the plasma sheet boundary layer after magnetic reconnection. At first, the double layers which have unipolar structures are formed. And then the double layers turn into bipolar structures, which will couple with another new weak bipolar structure. Thus a new double layer or tripolar structure comes into being. The double layers found in our work are about several ten Debye lengths, which accords with the observation results. It is suggested that the electron beam formed during the magnetic reconnection is responsible for the production of the double layers.

Highly Unstable Double-Diffusive Finger Convection in a Hele-Shaw Cell: Baseline Experimental Data for Evaluation of Numerical Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

PRINGLE,SCOTT E.; COOPER,CLAY A.; GLASS JR.,ROBERT J.

An experimental investigation was conducted to study double-diffusive finger convection in a Hele-Shaw cell by layering a sucrose solution over a more-dense sodium chloride (NaCl) solution. The solutal Rayleigh numbers were on the order of 60,000, based upon the height of the cell (25 cm), and the buoyancy ratio was 1.2. A full-field light transmission technique was used to measure a dye tracer dissolved in the NaCl solution. They analyze the concentration fields to yield the temporal evolution of length scales associated with the vertical and horizontal finger structure as well as the mass flux. These measures show a rapidmore » progression through two early stages to a mature stage and finally a rundown period where mass flux decays rapidly. The data are useful for the development and evaluation of numerical simulators designed to model diffusion and convection of multiple components in porous media. The results are useful for correct formulation at both the process scale (the scale of the experiment) and effective scale (where the lab-scale processes are averaged-up to produce averaged parameters). A fundamental understanding of the fine-scale dynamics of double-diffusive finger convection is necessary in order to successfully parameterize large-scale systems.« less

Comparison of double dose plateletpheresis on the Fenwal Amicus, Fresenius COM.TEC and Trima Accel cell separators.

PubMed

Keklik, Muzaffer; Eser, Bulent; Kaynar, Leylagul; Solmaz, Musa; Ozturk, Ahmet; Yay, Mehmet; Birekul, Ayse; Oztekin, Mehmet; Sivgin, Serdar; Cetin, Mustafa; Unal, Ali

2014-10-01

A variety of apheresis instruments are now available on the market for double dose plateletpheresis. We compared three apheresis devices (Fenwal Amicus, Fresenius COM.TEC and Trima Accel) with regard to processing time, platelet (PLT) yield, collection efficiency (CE) and collection rate (CR). The single-needle or double-needle double plateletpheresis procedures of the three instruments were compared in a retrospective, randomized study in 135 donors. In the pre-apheresis setting, 45 double plateletpheresis procedures performed with each instrument revealed no significant differences in donor's age, sex, weight, hemoglobin, white blood cell and PLT count between three groups. The blood volume processed to reach a target PLT yield of ≥ 6 × 10(11) was higher in the COM.TEC compared with the Amicus and Trima (4394 vs. 3780 and 3340 ml, respectively; p < 0.001). Also there was a significantly higher median volume of ACD used in collections on the COM.TEC compared with the Amicus and Trima (426 vs. 387 and 329 ml, respectively; p < 0.001). There was a significantly higher median time needed for the procedures on the COM.TEC compared with the Amicus and Trima (66 vs. 62 and 63 min, respectively; p = 0.024). The CE was significantly higher with the Trima compared with the Amicus and COM.TEC (83.57 ± 17.19 vs. 66.71 ± 3.47 and 58.79 ± 5.14%, respectively; p < 0.001). Also, there was a significantly higher product volume on the Trima compared with the Amicus and COM.TEC (395.56 vs. 363.11 and 386.4 ml, respectively; p = 0.008). Additionally, the CR was significantly lower with the COM.TEC compared with the Amicus and Trima (0.092 ± 0.011 vs. 0.099 ± 0.013 and 0.097 ± 0.013 plt × 10(11)/min, respectively; p = 0.039). There was no significant differences in PLT yield between the three groups (p = 0.636). Trima single-needle device collected double dose platelets more efficiently than Amicus and

Double Your Major, Double Your Return?

ERIC Educational Resources Information Center

Del Rossi, Alison F.; Hersch, Joni

2008-01-01

We use the 2003 National Survey of College Graduates to provide the first estimates of the effect on earnings of having a double major. Overall, double majoring increases earnings by 2.3% relative to having a single major among college graduates without graduate degrees. Most of the gains from having a double major come from choosing fields across…

A Wortmannin-Cetuximab As A Double Drug

PubMed Central

Smith, R. Adam; Yuan, Hushan; Weissleder, Ralph; Cantley, Lewis C.; Josephson, Lee

2012-01-01

Double drugs are obtained when two pharmacologically active entities are covalently joined to improve potency. We conjugated the viridin Wm with a self-activating linkage to cetuximab and demonstrated the retention of immunoreactivity by the conjugate. Though cetuximab lacked a growth inhibitory activity against A549 cells, the Wmcetuximab conjugate had an anti-proliferative IC50 of 155 nM in vitro. The chemistry of attaching a self-releasing Wm to clinically approved antibodies is general and, in selected instances, may yield antibody-based double drugs with improved efficacy. PMID:19883074

The double identity of linguistic doubling.

PubMed

Berent, Iris; Bat-El, Outi; Brentari, Diane; Dupuis, Amanda; Vaknin-Nusbaum, Vered

2016-11-29

Does knowledge of language consist of abstract principles, or is it fully embodied in the sensorimotor system? To address this question, we investigate the double identity of doubling (e.g., slaflaf, or generally, XX; where X stands for a phonological constituent). Across languages, doubling is known to elicit conflicting preferences at different levels of linguistic analysis (phonology vs. morphology). Here, we show that these preferences are active in the brains of individual speakers, and they are demonstrably distinct from sensorimotor pressures. We first demonstrate that doubling in novel English words elicits divergent percepts: Viewed as meaningless (phonological) forms, doubling is disliked (e.g., slaflaf < slafmak), but once doubling in form is systematically linked to meaning (e.g., slaf = ball, slaflaf = balls), the doubling aversion shifts into a reliable (morphological) preference. We next show that sign-naive speakers spontaneously project these principles to novel signs in American Sign Language, and their capacity to do so depends on the structure of their spoken language (English vs. Hebrew). These results demonstrate that linguistic preferences doubly dissociate from sensorimotor demands: A single stimulus can elicit diverse percepts, yet these percepts are invariant across stimulus modality--for speech and signs. These conclusions are in line with the possibility that some linguistic principles are abstract, and they apply broadly across language modality.

It Takes Two to Tango-Double-Layer Selective Contacts in Perovskite Solar Cells for Improved Device Performance and Reduced Hysteresis.

PubMed

Kegelmann, Lukas; Wolff, Christian M; Awino, Celline; Lang, Felix; Unger, Eva L; Korte, Lars; Dittrich, Thomas; Neher, Dieter; Rech, Bernd; Albrecht, Steve

2017-05-24

Solar cells made from inorganic-organic perovskites have gradually approached market requirements as their efficiency and stability have improved tremendously in recent years. Planar low-temperature processed perovskite solar cells are advantageous for possible large-scale production but are more prone to exhibiting photocurrent hysteresis, especially in the regular n-i-p structure. Here, a systematic characterization of different electron selective contacts with a variety of chemical and electrical properties in planar n-i-p devices processed below 180 °C is presented. The inorganic metal oxides TiO 2 and SnO 2 , the organic fullerene derivatives C 60 , PCBM, and ICMA, as well as double-layers with a metal oxide/PCBM structure are used as electron transport materials (ETMs). Perovskite layers deposited atop the different ETMs with the herein applied fabrication method show a similar morphology according to scanning electron microscopy. Further, surface photovoltage spectroscopy measurements indicate comparable perovskite absorber qualities on all ETMs, except TiO 2 , which shows a more prominent influence of defect states. Transient photoluminescence studies together with current-voltage scans over a broad range of scan speeds reveal faster charge extraction, less pronounced hysteresis effects, and higher efficiencies for devices with fullerene compared to those with metal oxide ETMs. Beyond this, only double-layer ETM structures substantially diminish hysteresis effects for all performed scan speeds and strongly enhance the power conversion efficiency up to a champion stabilized value of 18.0%. The results indicate reduced recombination losses for a double-layer TiO 2 /PCBM contact design: First, a reduction of shunt paths through the fullerene to the ITO layer. Second, an improved hole blocking by the wide band gap metal oxide. Third, decreased transport losses due to an energetically more favorable contact, as implied by photoelectron spectroscopy measurements

The mechanical properties and cytotoxicity of cell-laden double-network hydrogels based on photocrosslinkable gelatin and gellan gum biomacromolecules

PubMed Central

Shin, Hyeongho; Olsen, Bradley D.; Khademhosseini, Ali

2012-01-01

A major goal in the application of hydrogels for tissue engineering scaffolds, especially for load-bearing tissues such as cartilage, is to develop hydrogels with high mechanical strength. In this study, a double-network (DN) strategy was used to engineer strong hydrogels that can encapsulate cells. We improved upon previously studied double-network (DN) hydrogels by using a processing condition compatible with cell survival. The DN hydrogels were created by a two-step photocrosslinking using gellan gum methacrylate (GGMA) for the rigid and brittle first network, and gelatin methacrylamide (GelMA) for the soft and ductile second network. We controlled the degree of methacrylation of each polymer so that they obtain relevant mechanical properties as each network. The DN was formed by photocrosslinking the GGMA, diffusing GelMA into the first network, and photocrosslinking the GelMA to form the second network. The formation of the DN was examined by diffusion tests of the large GelMA molecules into the GGMA network, the resulting enhancement in the mechanical properties, and the difference in mechanical properties between GGMA/GelMA single networks (SN) and DNs. The resulting DN hydrogels exhibited the compressive failure stress of up to 6.9 MPa, which approaches the strength of cartilage. It was found that there is an optimal range of the crosslink density of the second network for high strength of DN hydrogels. DN hydrogels with a higher mass ratio of GelMA to GGMA exhibited higher strength, which shows promise in developing even stronger DN hydrogels in the future. Three dimensional (3D) encapsulation of NIH-3T3 fibroblasts and the following viability test showed the cell-compatibility of the DN formation process. Given the high strength and the ability to encapsulate cells, the DN hydrogels made from photocrosslinkable macromolecules could be useful for the regeneration of load-bearing tissues. PMID:22265786

Asymmetric segregation of the double-stranded RNA binding protein Staufen2 during mammalian neural stem cell divisions promotes lineage progression.

PubMed

Kusek, Gretchen; Campbell, Melissa; Doyle, Frank; Tenenbaum, Scott A; Kiebler, Michael; Temple, Sally

2012-10-05

Asymmetric cell divisions are a fundamental feature of neural development, and misregulation can lead to brain abnormalities or tumor formation. During an asymmetric cell division, molecular determinants are segregated preferentially into one daughter cell to specify its fate. An important goal is to identify the asymmetric determinants in neural progenitor cells, which could be tumor suppressors or inducers of specific neural fates. Here, we show that the double-stranded RNA-binding protein Stau2 is distributed asymmetrically during progenitor divisions in the developing mouse cortex, preferentially segregating into the Tbr2(+) neuroblast daughter, taking with it a subset of RNAs. Knockdown of Stau2 stimulates differentiation and overexpression produces periventricular neuronal masses, demonstrating its functional importance for normal cortical development. We immunoprecipitated Stau2 to examine its cargo mRNAs, and found enrichment for known asymmetric and basal cell determinants, such as Trim32, and identified candidates, including a subset involved in primary cilium function. Copyright © 2012 Elsevier Inc. All rights reserved.

Asymmetric Segregation of the Double-Stranded RNA Binding Protein Staufen2 during Mammalian Neural Stem Cell Divisions Promotes Lineage Progression

PubMed Central

Kusek, Gretchen; Campbell, Melissa; Doyle, Frank; Tenenbaum, Scott A.; Kiebler, Michael; Temple, Sally

2012-01-01

Summary Asymmetric cell divisions are a fundamental feature of neural development, and misregulation can lead to brain abnormalities or tumor formation. During an asymmetric cell division, molecular determinants are segregated preferentially into one daughter cell to specify its fate. An important goal is to identify the asymmetric determinants in neural progenitor cells, which could be tumor suppressors or inducers of specific neural fates. Here we show that the double-stranded RNA-binding protein Stau2 is distributed asymmetrically during progenitor divisions in the developing mouse cortex, preferentially segregating into the Tbr2+ neuroblast daughter, taking with it a sub-set of RNAs. Knockdown of Stau2 stimulates differentiation and over-expression produces periventricular neuronal masses, demonstrating its functional importance for normal cortical development. We immunoprecipitated Stau2 to examine its cargo mRNAs, and found enrichment for known asymmetric and basal cell determinants, such as Trim32, and identified novel candidates, including a subset involved in primary cilium function. PMID:22902295

Double control systems for human T-cell leukemia virus type 1 by innate and acquired immunity.

PubMed

Kannagi, Mari; Hasegawa, Atsuhiko; Kinpara, Shuichi; Shimizu, Yukiko; Takamori, Ayako; Utsunomiya, Atae

2011-04-01

Human T-cell leukemia virus type 1 (HTLV-1) is the causative retrovirus of adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-1-specific T-cell responses elicit antitumor and antiviral effects in experimental models, and are considered to be one of the most important determinants of the disease manifestation, since they are activated in HAM/TSP but not in ATL patients. The combination of low T-cell responses and elevated HTLV-1 proviral loads are features of ATL, and are also observed in a subpopulation of HTLV-1 carriers at the asymptomatic stage, suggesting that these features may be underlying risk factors. These risks may potentially be reduced by vaccination to activate HTLV-1-specific T-cell responses. HAM/TSP and ATL patients also differ in their levels of HTLV-1 mRNA expression, which are generally low in vivo but slightly higher in HAM/TSP patients. Our recent study indicated that viral expression in HTLV-1-infected T-cells is suppressed by stromal cells in culture through type-I IFNs. The suppression was reversible after isolation from the stromal cells, mimicking a long-standing puzzling phenomenon in HTLV-1 infection where the viral expression is very low in vivo and rapidly induced in vitro. Collectively, HTLV-1 is controlled by both acquired and innate immunity in vivo: HTLV-1-specific T-cells survey infected cells, and IFNs suppress viral expression. Both effects would contribute to a reduction in viral pathogenesis, although they may potentially influence or conflict with one another. The presence of double control systems for HTLV-1 infection provides a new concept for understanding the pathogenesis of HTLV-1-mediated malignant and inflammatory diseases. © 2011 Japanese Cancer Association.

Single- and double-walled carbon nanotubes enhance atherosclerogenesis by promoting monocyte adhesion to endothelial cells and endothelial progenitor cell dysfunction.

PubMed

Suzuki, Yuka; Tada-Oikawa, Saeko; Hayashi, Yasuhiko; Izuoka, Kiyora; Kataoka, Misa; Ichikawa, Shunsuke; Wu, Wenting; Zong, Cai; Ichihara, Gaku; Ichihara, Sahoko

2016-10-13

The use of carbon nanotubes has increased lately. However, the cardiovascular effect of exposure to carbon nanotubes remains elusive. The present study investigated the effects of pulmonary exposure to single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) on atherosclerogenesis using normal human aortic endothelial cells (HAECs) and apolipoprotein E-deficient (ApoE -/- ) mice, a model of human atherosclerosis. HAECs were cultured and exposed to SWCNTs or DWCNTs for 16 h. ApoE -/- mice were exposed to SWCNTs or DWCNTs (10 or 40 μg/mouse) once every other week for 10 weeks by pharyngeal aspiration. Exposure to CNTs increased the expression level of adhesion molecule (ICAM-1) and enhanced THP-1 monocyte adhesion to HAECs. ApoE -/- mice exposed to CNTs showed increased plaque area in the aorta by oil red O staining and up-regulation of ICAM-1 expression in the aorta, compared with vehicle-treated ApoE -/- mice. Endothelial progenitor cells (EPCs) are mobilized from the bone marrow into the circulation and subsequently migrate to the site of endothelial damage and repair. Exposure of ApoE -/- mice to high-dose SWCNTs or DWCNTs reduced the colony-forming units of EPCs in the bone marrow and diminished their migration function. The results suggested that SWCNTs and DWCNTs enhanced atherosclerogenesis by promoting monocyte adhesion to endothelial cells and inducing EPC dysfunction.

Design, fabrication and characterization of a double layer solid oxide fuel cell (DLFC)

NASA Astrophysics Data System (ADS)

Wang, Guangjun; Wu, Xiangying; Cai, Yixiao; Ji, Yuan; Yaqub, Azra; Zhu, Bin

2016-11-01

A double layer solid oxide fuel cell (DLSOFC) without using the electrolyte (layer) has been designed by integrating advantages of positive electrode material of lithium ion battery(LiNi0.8Co0.15Al0.05O2) and oxygen-permeable membranes material (trace amount cobalt incorporated terbium doped ceria, TDC + Co) based on the semiconductor physics principle. Instead of using an electrolyte layer, the depletion layer between the anode and cathode served as an electronic insulator to block the electrons but to maintain the electrolyte function for ionic transport. Thus the device with two layers can realize the function of SOFC and at the same time avoids the electronic short circuiting problem. Such novel DLFC showed good performance at low temperatures, for instance, a maximum power density of 230 mWcm-2 was achieved at 500 °C. The working principle of the new device is presented.

Irreparable complex DNA double-strand breaks induce chromosome breakage in organotypic three-dimensional human lung epithelial cell culture

PubMed Central

Asaithamby, Aroumougame; Hu, Burong; Delgado, Oliver; Ding, Liang-Hao; Story, Michael D.; Minna, John D.; Shay, Jerry W.; Chen, David J.

2011-01-01

DNA damage and consequent mutations initiate the multistep carcinogenic process. Differentiated cells have a reduced capacity to repair DNA lesions, but the biological impact of unrepaired DNA lesions in differentiated lung epithelial cells is unclear. Here, we used a novel organotypic human lung three-dimensional (3D) model to investigate the biological significance of unrepaired DNA lesions in differentiated lung epithelial cells. We showed, consistent with existing notions that the kinetics of loss of simple double-strand breaks (DSBs) were significantly reduced in organotypic 3D culture compared to kinetics of repair in two-dimensional (2D) culture. Strikingly, we found that, unlike simple DSBs, a majority of complex DNA lesions were irreparable in organotypic 3D culture. Levels of expression of multiple DNA damage repair pathway genes were significantly reduced in the organotypic 3D culture compared with those in 2D culture providing molecular evidence for the defective DNA damage repair in organotypic culture. Further, when differentiated cells with unrepaired DNA lesions re-entered the cell cycle, they manifested a spectrum of gross-chromosomal aberrations in mitosis. Our data suggest that downregulation of multiple DNA repair pathway genes in differentiated cells renders them vulnerable to DSBs, promoting genome instability that may lead to carcinogenesis. PMID:21421565

Double versus single high-dose melphalan 200 mg/m2 and autologous stem cell transplantation for multiple myeloma: a region-based study in 484 patients from the Nordic area

PubMed Central

Björkstrand, Bo; Klausen, Tobias W.; Remes, Kari; Gruber, Astrid; Knudsen, Lene M.; Bergmann, Olav J.; Lenhoff, Stig; Johnsen, Hans E.

2009-01-01

Autologous stem cell transplantation is still considered the standard of care in young patients with multiple myeloma (MM). This disease is the most common indication for high-dose therapy (HDT) supported by hematopoietic stem cell transplantation and much data support the benefit of this procedure. Results of randomized studies are in favor of tandem autologous transplantation although the effect on overall survival is unclear. Based on sequential registration trials in the Nordic area, we aimed to evaluate the outcome of conventional single or double HDT. During 1994–2000 we registered a total of 484 previously untreated patients under the age of 60 years at diagnosis who on a regional basis initially were treated with single [Trial NMSG #5/94 and #7/98 (N=383)] or double [Trial Huddinge Karolinska Turku Herlev (N=101)] high-dose melphalan (200 mg/m2) therapy supported by autologous stem cell transplantation. A complete or very good partial response was achieved by 40% of patients in the single transplant group and 60% of patients in the double transplant group (p=0.0006). The probability of surviving progression free for five years after the diagnosis was 25% (95% CL 18–32%) in the singletransplant group and 46% (95% CL 33–55%) in the double transplant group (p=0.0014). The estimated overall five-year survival rate was 60% in the single transplant group and 64% in the doubletransplant (p=0.9). In a multivariate analysis of variables, including single versus double transplantation, β2 microglobulin level, age, sex and disease stage, only β2 microglobulin level was predictive for overall survival (p>0.0001) and progression free survival (p=0.001). In accordance with these results, a 1:1 case-control matched comparison between double and single transplantation did not identify significant differences in overall and progression free survival. In this retrospective analysis up front double transplantation with melphalan (200 mg/m2) as compared to single

Selective Cell Adhesion and Biosensing Applications of Bio-Active Block Copolymers Prepared by CuAAC/Thiol-ene Double Click Reactions.

PubMed

Oyman Eyrilmez, Gizem; Doran, Sean; Murtezi, Eljesa; Demir, Bilal; Odaci Demirkol, Dilek; Coskunol, Hakan; Timur, Suna; Yagci, Yusuf

2015-09-01

N-Acetyl-l-cysteine (NAC)-capped poly(methyl methacrylate)-b-polycaprolactone block copolymer (PMMA-b-PCL-NAC) was prepared using the previously described one-pot photoinduced sequential CuAAC/thiol-ene double click procedure. PMMA-b-PCL-NAC had previously shown good applicability as a matrix for cell adhesion of cells from the Vero cell line (African green monkey kidney epithelial). Here, in this work, PMMA-b-PCL-NAC served as an excellent immobilization matrix for biomolecule conjugation. Covalent binding of RGD (R: arginine, G: glycine, and D: aspartic acid) peptide sequence onto the PMMA-b-PCL-NAC-coated surface was performed via EDC chemistry. RGD-modified PMMA-b-PCL-NAC (PMMA-b-PCL-NAC-RGD) as a non-toxic cell proliferation platform was used for selective "integrin αvβ3-mediated cell adhesion and biosensing studies. Both optical and electrochemical techniques were used to monitor the adhesion differences between "integrin αvβ3" receptor positive and negative cell lines on to the designed biofunctional surfaces. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mechanical response of biopolymer double networks

NASA Astrophysics Data System (ADS)

Carroll, Joshua; Das, Moumita

We investigate a double network model of articular cartilage (AC) and characterize its equilibrium mechanical response. AC has very few cells and the extracellular matrix mainly determines its mechanical response. This matrix can be thought of as a double polymer network made of collagen and aggrecan. The collagen fibers are stiff and resist tension and compression forces, while aggrecans are flexible and control swelling and hydration. We construct a microscopic model made of two interconnected disordered polymer networks, with fiber elasticity chosen to qualitatively mimic the experimental system. We study the collective mechanical response of this double network as a function of the concentration and stiffness of the individual components as well as the strength of the connection between them using rigidity percolation theory. Our results may provide a better understanding of mechanisms underlying the mechanical resilience of AC, and more broadly may also lead to new perspectives on the mechanical response of multicomponent soft materials. This work was partially supported by a Cottrell College Science Award.

A medulloblastoma showing an unusually long doubling time: reflection of its singular nature.

PubMed

Doron, Omer; Zauberman, Jacob; Feldman, Ze'ev

2016-06-01

In this paper, we present a case of a 4-year-old male diagnosed with a desmoplastic, SHH-type medulloblastoma. Retrospectively, we discovered that the patient underwent an MRI scan at 21 months for reasons unrelated, revealing a T1-enhanced lesion at the vermis, later recognized as the source of the tumor. This unique case provides us with a glimpse into the natural history of this tumor. Our ability to measure tumor volume at two defined time points, 31 months apart, enabled us to deduce the tumor's doubling time. This is defined as the time of one cell cycle divided by the amount of cycling cells, multiplied by cell loss factor. Potential doubling time (Tpot) and actual doubling time (Td), calculated using the Gompertzian model, are the most clinically relevant with regard to a tumor's response to radiotherapy. Here, we show an actual doubling-time (Td) of 78 days, and an extrapolated tumor diameter at the time of birth of 0.25 mm. These results both support the medulloblastoma's embryonic origin, and indicating a threefold longer actual doubling time when compared to previous studies. Taking into account the reported range of medulloblastoma potential doubling time, we deduced a cell loss factor of between 48.9 and 95.5 %. These percentages fall in line with other malignant tumors. Although limited due to the obvious reliance on only two points in time and using the Gompertzian model to complete the remainder, to the best of our knowledge, this is the longest follow-up period reported for medulloblastoma. We have described how a unique turn of events enabled us to get a glimpse into the in situ development of a medulloblastoma over a 31-month period. Regarded sometimes as an idiosyncratic tumor comprised of an array of molecular changes, the complexity of medulloblastoma is displayed here, by revealing for the first time an actual doubling time three- to fourfold the previously known length.

Numerically simulated two-dimensional auroral double layers

NASA Technical Reports Server (NTRS)

Borovsky, J. E.; Joyce, G.

1983-01-01

A magnetized 2 1/2-dimensional particle-in-cell system which is periodic in one direction and bounded by reservoirs of Maxwellian plasma in the other is used to numerically simulate electrostatic plasma double layers. For the cases of both oblique and two-dimensional double layers, the present results indicate periodic instability, Debye length rather than gyroradii scaling, and low frequency electrostatic turbulence together with electron beam-excited electrostatatic electron-cyclotron waves. Estimates are given for the thickness of auroral doule layers, as well as the separations within multiple auroral arcs. Attention is given to the temporal modulation of accelerated beams, and the possibilities for ion precipitation and ion conic production by the double layer are hypothesized. Simulations which include the atmospheric backscattering of electrons imply the action of an ionospheric sheath which accelerates ionospheric ions upward.

Inhibition of APOBEC3G activity impedes double-stranded DNA repair.

PubMed

Prabhu, Ponnandy; Shandilya, Shivender M D; Britan-Rosich, Elena; Nagler, Adi; Schiffer, Celia A; Kotler, Moshe

2016-01-01

The cellular cytidine deaminase APOBEC3G (A3G) was first described as an anti-HIV-1 restriction factor, acting by directly deaminating reverse transcripts of the viral genome. HIV-1 Vif neutralizes the activity of A3G, primarily by mediating degradation of A3G to establish effective infection in host target cells. Lymphoma cells, which express high amounts of A3G, can restrict Vif-deficient HIV-1. Interestingly, these cells are more stable in the face of treatments that result in double-stranded DNA damage, such as ionizing radiation and chemotherapies. Previously, we showed that the Vif-derived peptide (Vif25-39) efficiently inhibits A3G deamination, and increases the sensitivity of lymphoma cells to ionizing radiation. In the current study, we show that additional peptides derived from Vif, A3G, and APOBEC3F, which contain the LYYF motif, inhibit deamination activity. Each residue in the Vif25-39 sequence moderately contributes to the inhibitory effect, whereas replacing a single residue in the LYYF motif completely abrogates inhibition of deamination. Treatment of A3G-expressing lymphoma cells exposed to ionizing radiation with the new inhibitory peptides reduces double-strand break repair after irradiation. Incubation of cultured irradiated lymphoma cells with peptides that inhibit double-strand break repair halts their propagation. These results suggest that A3G may be a potential therapeutic target that is amenable to peptide and peptidomimetic inhibition. © 2015 FEBS.

Optimization of Monocrystalline MgxCd1-xTe/MgyCd1-yTe Double-Heterostructure Solar Cells

NASA Astrophysics Data System (ADS)

Becker, Jacob J.

Polycrystalline CdS/CdTe solar cells continue to dominate the thin-film photovoltaics industry with an achieved record efficiency of over 22% demonstrated by First Solar, yet monocrystalline CdTe devices have received considerably less attention over the years. Monocrystalline CdTe double-heterostructure solar cells show great promise with respect to addressing the problem of low Voc with the passing of the 1 V benchmark. Rapid progress has been made in driving the efficiency in these devices ever closer to the record presently held by polycrystalline thin-films. This achievement is primarily due to the utilization of a remote p-n heterojunction in which the heavily doped contact materials, which are so problematic in terms of increasing non-radiative recombination inside the absorber, are moved outside of the CdTe double heterostructure with two MgyCd1-yTe barrier layers to provide confinement and passivation at the CdTe surfaces. Using this design, the pursuit and demonstration of efficiencies beyond 20% in CdTe solar cells is reported through the study and optimization of the structure barriers, contacts layers, and optical design. Further development of a wider bandgap MgxCd1-xTe solar cell based on the same design is included with the intention of applying this knowledge to the development of a tandem solar cell constructed on a silicon subcell. The exploration of different hole-contact materials--ZnTe, CuZnS, and a-Si:H--and their optimization is presented throughout the work. Devices utilizing a-Si:H hole contacts exhibit open-circuit voltages of up to 1.11 V, a maximum total-area efficiency of 18.5% measured under AM1.5G, and an active-area efficiency of 20.3% for CdTe absorber based devices. The achievement of voltages beyond 1.1V while still maintaining relatively high fill factors with no rollover, either before or after open-circuit, is a promising indicator that this approach can result in devices surpassing the 22% record set by polycrystalline

Doubled haploid production in Flax (Linum usitatissimum L.).

PubMed

Obert, Bohus; Zácková, Zuzana; Samaj, Jozef; Pretová, Anna

2009-01-01

There is a requirement of haploid and double haploid material and homozygous lines for cell culture studies and breeding in flax. Anther culture is currently the most successful method producing doubled haploid lines in flax. Recently, ovary culture was also described as a good source of doubled haploids. In this review we focus on tissue and plants regeneration using anther culture, and cultivation of ovaries containing unfertilized ovules. The effect of genotype, physiological status of donor plants, donor material pre-treatment and cultivation conditions for flax anthers and ovaries is discussed here. The process of plant regeneration from anther and ovary derived calli is also in the focus of this review. Attention is paid to the ploidy level of regenerated tissue and to the use of molecular markers for determining of gametic origin of flax plants derived from anther and ovary cultures. Finally, some future prospects on the use of doubled haploids in flax biotechnology are outlined here.

Hybrid Dye-Sensitized Solar Cells Consisting of Double Titania Layers for Harvesting Light with Wide Range of Wavelengths

NASA Astrophysics Data System (ADS)

Sadamasu, Kengo; Inoue, Takafumi; Ogomi, Yuhei; Pandey, Shyam S.; Hayase, Shuzi

2011-02-01

We report a hybrid dye-sensitized solar cell consisting of double titania layers (top and bottom layers) stained with two dyes. A top layer fabricated on a glass was mechanically pressed with a bottom layer fabricated on a glass cloth. The glass cloth acts as a supporter of a porous titania layer as well as a holder of electrolyte. The incident photon to current efficiency (IPCE) curve had two peaks corresponding to those of the two dyes, which demonstrates that electrons are collected from both the top and bottom layers.

In trans paired nicking triggers seamless genome editing without double-stranded DNA cutting.

PubMed

Chen, Xiaoyu; Janssen, Josephine M; Liu, Jin; Maggio, Ignazio; 't Jong, Anke E J; Mikkers, Harald M M; Gonçalves, Manuel A F V

2017-09-22

Precise genome editing involves homologous recombination between donor DNA and chromosomal sequences subjected to double-stranded DNA breaks made by programmable nucleases. Ideally, genome editing should be efficient, specific, and accurate. However, besides constituting potential translocation-initiating lesions, double-stranded DNA breaks (targeted or otherwise) are mostly repaired through unpredictable and mutagenic non-homologous recombination processes. Here, we report that the coordinated formation of paired single-stranded DNA breaks, or nicks, at donor plasmids and chromosomal target sites by RNA-guided nucleases based on CRISPR-Cas9 components, triggers seamless homology-directed gene targeting of large genetic payloads in human cells, including pluripotent stem cells. Importantly, in addition to significantly reducing the mutagenicity of the genome modification procedure, this in trans paired nicking strategy achieves multiplexed, single-step, gene targeting, and yields higher frequencies of accurately edited cells when compared to the standard double-stranded DNA break-dependent approach.CRISPR-Cas9-based gene editing involves double-strand breaks at target sequences, which are often repaired by mutagenic non-homologous end-joining. Here the authors use Cas9 nickases to generate coordinated single-strand breaks in donor and target DNA for precise homology-directed gene editing.

Acousto-optical modulation of light at a doubled sound frequency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kotov, V M; Averin, S V; Shkerdin, G N

2016-02-28

A method of acousto-optical (AO) Bragg diffraction is proposed that provides the amplitude modulation of optical radiation at a doubled acoustic frequency. The method is based on the double transmission of the light through the AO modulator made of a gyrotropic crystal and is experimentally tested by the example of the modulation of light with a wavelength of 0.63 μm, controlled by the paratellurite AO cell. (acoustooptics)

Nucleotide excision repair-dependent DNA double-strand break formation and ATM signaling activation in mammalian quiescent cells.

PubMed

Wakasugi, Mitsuo; Sasaki, Takuma; Matsumoto, Megumi; Nagaoka, Miyuki; Inoue, Keiko; Inobe, Manabu; Horibata, Katsuyoshi; Tanaka, Kiyoji; Matsunaga, Tsukasa

2014-10-10

Histone H2A variant H2AX is phosphorylated at Ser(139) in response to DNA double-strand break (DSB) and single-stranded DNA (ssDNA) formation. UV light dominantly induces pyrimidine photodimers, which are removed from the mammalian genome by nucleotide excision repair (NER). We previously reported that in quiescent G0 phase cells, UV induces ATR-mediated H2AX phosphorylation plausibly caused by persistent ssDNA gap intermediates during NER. In this study, we have found that DSB is also generated following UV irradiation in an NER-dependent manner and contributes to an earlier fraction of UV-induced H2AX phosphorylation. The NER-dependent DSB formation activates ATM kinase and triggers the accumulation of its downstream factors, MRE11, NBS1, and MDC1, at UV-damaged sites. Importantly, ATM-deficient cells exhibited enhanced UV sensitivity under quiescent conditions compared with asynchronously growing conditions. Finally, we show that the NER-dependent H2AX phosphorylation is also observed in murine peripheral T lymphocytes, typical nonproliferating quiescent cells in vivo. These results suggest that in vivo quiescent cells may suffer from NER-mediated secondary DNA damage including ssDNA and DSB. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

In silico characterization of cell-cell interactions using a cellular automata model of cell culture.

PubMed

Kihara, Takanori; Kashitani, Kosuke; Miyake, Jun

2017-07-14

Cell proliferation is a key characteristic of eukaryotic cells. During cell proliferation, cells interact with each other. In this study, we developed a cellular automata model to estimate cell-cell interactions using experimentally obtained images of cultured cells. We used four types of cells; HeLa cells, human osteosarcoma (HOS) cells, rat mesenchymal stem cells (MSCs), and rat smooth muscle A7r5 cells. These cells were cultured and stained daily. The obtained cell images were binarized and clipped into squares containing about 10 4 cells. These cells showed characteristic cell proliferation patterns. The growth curves of these cells were generated from the cell proliferation images and we determined the doubling time of these cells from the growth curves. We developed a simple cellular automata system with an easily accessible graphical user interface. This system has five variable parameters, namely, initial cell number, doubling time, motility, cell-cell adhesion, and cell-cell contact inhibition (of proliferation). Within these parameters, we obtained initial cell numbers and doubling times experimentally. We set the motility at a constant value because the effect of the parameter for our simulation was restricted. Therefore, we simulated cell proliferation behavior with cell-cell adhesion and cell-cell contact inhibition as variables. By comparing growth curves and proliferation cell images, we succeeded in determining the cell-cell interaction properties of each cell. Simulated HeLa and HOS cells exhibited low cell-cell adhesion and weak cell-cell contact inhibition. Simulated MSCs exhibited high cell-cell adhesion and positive cell-cell contact inhibition. Simulated A7r5 cells exhibited low cell-cell adhesion and strong cell-cell contact inhibition. These simulated results correlated with the experimental growth curves and proliferation images. Our simulation approach is an easy method for evaluating the cell-cell interaction properties of cells.

Double Charge Exchange Reactions and Double Beta Decay

NASA Astrophysics Data System (ADS)

Auerbach, N.

2018-05-01

The subject of this presentation is at the forefront of nuclear physics, namely double beta decay. In particular one is most interested in the neutrinoless process of double beta decay, when the decay proceeds without the emission of two neutrinos. The observation of such decay would mean that the lepton conservation symmetry is violated and that the neutrinos are of Majorana type, meaning that they are their own anti-particles. The life time of this process has two unknowns, the mass of the neutrino and the nuclear matrix element. Determining the nuclear matrix element and knowing the cross-section well will set limits on the neutrino mass. There is a concentrated effort among the nuclear physics community to calculate this matrix element. Usually these matrix elements are a very small part of the total strength of the transition operators involved in the process. There is no simple way to “calibrate” the nuclear double beta decay matrix element. The double beta decay is a double charge exchange process, therefore it is proposed that double charge exchange reactions using ion projectiles on nuclei that are candidates for double beta decay, will provide additional necessary information about the nuclear matrix elements.

Expression of the stem cell factor in fibroblasts, endothelial cells, and macrophages in periapical tissues in human chronic periapical diseases.

PubMed

Shen, S Q; Wang, R; Huang, S G

2017-03-08

Stem cell factor (SCF), an important stem cell cytokine, has multiple functions. Fibroblasts (FBs), mature mast cells, endothelial cells (ECs), and eosinophil granulocytes can produce SCF in the inflammatory process. Therefore, we aimed to observe SCF expression in FBs, ECs, and macrophages (MPs) in periapical tissues in human chronic periapical disease and investigate the effects of cells expressing SCF in pathogenesis of the disease. Healthy (N = 20), periapical cyst (N = 15), and periapical granuloma (N = 15) tissues were fixed in 10% formalin for 48 h, embedded in paraffin, and stained with hematoxylin and eosin to observe histological changes. SCF expression was observed in FBs, ECs, and MPs in periapical tissues by double immunofluorescence. CD334, CD31, and CD14 are specific markers of FBs, ECs, and MPs, respectively. Results showed that densities of CD334-SCF double-positive FBs, CD31-SCF double-positive ECs, and CD14-SCF double-positive MPs were significantly increased in periapical tissue groups (P < 0.01). There were no significant differences in CD334-SCF double-positive FB and CD31-SCF double-positive EC levels between the two periapical tissue groups (P > 0.05). CD14-SCF double-positive MP density was considerably higher in periapical granulomas than in cysts (P < 0.01). FB, EC, and MP levels were significantly high and densities of CD334-SCF double-positive FBs, CD31-SCF double-positive ECs, and CD14-SCF double-positive MPs improved considerably in chronic periapical tissues, suggesting that the cells might be related to occurrence, development, and pathogenesis of chronic periapical disease.

Improvement of insulin sensitivity and beta-cell function by nateglinide and repaglinide in type 2 diabetic patients - a randomized controlled double-blind and double-dummy multicentre clinical trial.

PubMed

Li, J; Tian, H; Li, Q; Wang, N; Wu, T; Liu, Y; Ni, Z; Yu, H; Liang, J; Luo, R; Li, Y; Huang, L

2007-07-01

To evaluate the efficacy of nateglinide vs. repaglinide in blood glucose (BG) control and the effect on insulin resistance and beta-Cell function in patients with type 2 diabetes. A randomized controlled double-blind and double-dummy multicentre clinical trial was conducted. A total of 230 Chinese patients with type 2 diabetes were enrolled in five clinical centres. The patients were divided randomly into group A [repaglinide 1.0 mg three times daily (t.i.d.), n = 115] or group B (nateglinide 90 mg t.i.d., n = 115). At baseline and end of the 12-week clinical trial, standard mixed meal tolerance tests were performed. A total of 223 patients (96.9%) completed the trial. There was no significant difference between repaglinide and nateglinide groups in the effects of reducing fasting blood glucose (FBG), 30-, 60- and 120-min BG during 12 weeks (p > 0.05). At week 12, no significant difference was shown between the two groups in BG or haemoglobin A(1c) (HbA(1c)) (p > 0.05). However, the effect on HbA(1c) in repaglinide group was stronger than that in nateglinide group (p < 0.05). After 12-week treatment, area under the curve (AUC) of BG decreased (p < 0.05), and AUC of insulin and C-peptide (CP) increased in both groups (p < 0.05). The effects of nateglinide on AUC of BG, insulin and CP were similar to that of repaglinide (p > 0.05). There was no significant difference between the two groups in AUC of BG, insulin or CP in week 12 (p > 0.05). Furthermore, homeostasis model assessment of insulin resistance (HOMA-IR) and beta-cell function indexes measured by HOMA-beta, DeltaI(30)/DeltaG(30) and (DeltaI(30)/DeltaG(30))/HOMA-IR were improved significantly in both groups during 12 weeks (p < 0.05). The effects of improving HOMA-IR and beta-cell function indexes in nateglinide group were comparable with that of repaglinide group (p > 0.05). The efficacy of repaglinide and nateglinide in FBG, postprandial glucose excursion and early-phase insulin secretion is similar. But the

The mechanical properties and cytotoxicity of cell-laden double-network hydrogels based on photocrosslinkable gelatin and gellan gum biomacromolecules.

PubMed

Shin, Hyeongho; Olsen, Bradley D; Khademhosseini, Ali

2012-04-01

A major goal in the application of hydrogels for tissue engineering scaffolds, especially for load-bearing tissues such as cartilage, is to develop hydrogels with high mechanical strength. In this study, a double-network (DN) strategy was used to engineer strong hydrogels that can encapsulate cells. We improved upon previously studied double-network (DN) hydrogels by using a processing condition compatible with cell survival. The DN hydrogels were created by a two-step photocrosslinking using gellan gum methacrylate (GGMA) for the rigid and brittle first network, and gelatin methacrylamide (GelMA) for the soft and ductile second network. We controlled the degree of methacrylation of each polymer so that they obtain relevant mechanical properties as each network. The DN was formed by photocrosslinking the GGMA, diffusing GelMA into the first network, and photocrosslinking the GelMA to form the second network. The formation of the DN was examined by diffusion tests of the large GelMA molecules into the GGMA network, the resulting enhancement in the mechanical properties, and the difference in mechanical properties between GGMA/GelMA single networks (SN) and DNs. The resulting DN hydrogels exhibited the compressive failure stress of up to 6.9 MPa, which approaches the strength of cartilage. It was found that there is an optimal range of the crosslink density of the second network for high strength of DN hydrogels. DN hydrogels with a higher mass ratio of GelMA to GGMA exhibited higher strength, which shows promise in developing even stronger DN hydrogels in the future. Three dimensional (3D) encapsulation of NIH-3T3 fibroblasts and the following viability test showed the cell-compatibility of the DN formation process. Given the high strength and the ability to encapsulate cells, the DN hydrogels made from photocrosslinkable macromolecules could be useful for the regeneration of load-bearing tissues. Copyright © 2012 Elsevier Ltd. All rights reserved.

Partial Pressures for Several In-Se Compositions from Optical Absorbance of the Vapor

NASA Technical Reports Server (NTRS)

Brebrick, R. F.; Su, Ching-Hua

2001-01-01

The optical absorbance of the vapor phase over various In-Se compositions between 33.3-60.99 at.% Se and 673-1418 K was measured and used to obtain the partial pressures of Se2(g) and In2Se(g). The results are in agreement with silica Bourdon gauge measurements for compositions between 50-61 at.%, but significantly higher than those from Knudsen cell and simultaneous Knudsen-torsion cell measurements. It is found that 60.99 at.% Se lies outside the sesquiselenide homogeneity range and 59.98 at.% Se lies inside and is the congruently melting composition. The Gibbs energy of formation of the liquid from its pure liquid elements between 1000-1300 K is essentially independent of temperature and falls between -36 to -38 kJ per g atomic weight for 50 and 56% Se at 1200 and 1300 K.

The cell biology of aging.

PubMed

Hayflick, L

1979-07-01

Cultured normal human and animal cells are predestinued to undergo irreversible functional decrements that mimick age changes in the whole organism. When normal human embryonic fibroblasts are cultured in vitro, 50 +/- 10 population doublings occur. This maximum potential is diminished in cells derived from older donors and appears to be inversely proportional to their age. The 50 population doubling limit can account for all cells produced during a lifetime. The limitation on doubling potential of cultured normal cells is also expressed in vivo when serial transplants are made. There may be a direct correlation between the mean maximum life spans of several species and the population doubling potential of their cultured cells. A plethora of functional decrements occur in cultured normal cells as they approach their maximum division capability. Many of these decrements are similar to those occurring in intact animals as they age. We have concluded that these functional decrements expressed in vitro, rather than cessation of cell division, are the essential contributors to age changes in intact animals. Thus, the study of events leading to functional losses in cultured normal cells may provide useful insights into the biology of aging.

The cell biology of aging.

PubMed

Hayflick, L

1985-02-01

It is only within the past ten years that biogerontology has become attractive to a sufficient number of biologists so that the field can be regarded as a seriously studied discipline. Cytogerontology, or the study of aging at the cellular level, had its genesis about 20 years ago when the dogma that maintained that cultured normal cells could replicate forever was overturned. Normal human and animal cells have a finite capacity to replicate and function whether they are cultured in vitro or transplanted as grafts in vivo. This phenomenon has been interpreted to be aging at the cellular level. Only abnormal somatic cells are capable of immortality. In recent years it has been found that the number of population doublings of which cultured normal cells are capable is inversely proportional to donor age. There is also good evidence that the number of population doublings of cultured normal fibroblasts is directly proportional to the maximum lifespan of ten species that have been studied. Cultures prepared from patients with accelerated aging syndromes (progeria and Werner's syndrome) undergo far fewer doublings than do those of age-matched controls. The normal human fibroblast cell strain WI-38 was established in 1962 from fetal lung, and several hundred ampules of these cells were frozen in liquid nitrogen at that time. These ampules have been reconstituted periodically and shown to be capable of replication. This represents the longest period of time that a normal human cell has ever been frozen. Normal human fetal cell strains such as WI-38 have the capacity to double only about 50 times. If cultures are frozen at various population doublings, the number of doublings remaining after reconstitution is equal to 50 minus the number of doublings that occurred prior to freezing. The memory of the cells has been found to be accurate after 23 years of preservation in liquid nitrogen. Normal human cells incur many physiologic decrements that herald the approach of their

EBV-associated but HHV8-unrelated double-hit effusion-based lymphoma.

PubMed

Chen, Bo-Jung; Chen, David Yen-Ting; Kuo, Chun-Chi; Chuang, Shih-Sung

2017-03-01

Effusion-based lymphoma is a rare and unique type of large B-cell lymphoma presenting in effusion without a mass lesion. It shares many clinicopathological features with primary effusion lymphoma (PEL), but is distinct from PEL by the absence of HHV8 association. Double hit lymphoma (DHL) is an aggressive B-cell lymphoma, defined by concurrent rearrangement of MYC and BCL2 or BCL6. DHL often presents as lymphadenopathy or an extranodal mass, but rarely occurs in effusion. Here we report a 61-year-old male with alcoholic cirrhosis presenting as massive ascites and left pleural effusion. He has no HIV, HBV or HCV infection and no mass lesion by CT scans. Cytology of both pleural effusion and ascites show large lymphoma cells with plasmablastic morphology characterized by pleomorphic and eccentric nuclei, prominent nucleoli and frequent mitoses. Immunohistochemical study with cell block shows that the lymphoma cells express plasma cell-related markers (CD138, MUM-1 and EMA), but not CD3, CD30, CD45, B-cell markers (CD19, CD20, CD79a, and PAX5), HHV8, ALK or cytokeratin. EBER is positive in most lymphoma cells. Fluorescence in situ hybridization reveals rearrangement at the IGH, BCL2, and MYC loci, but not at BCL6. It is diagnosed as an EBV-associated but HHV8-unrelated double hit effusion-based lymphoma with plasmablastic features. The patient passed away soon after diagnosis without chemotherapy. This is the first reported case of double-hit effusion-based lymphoma with MYC and BCL2 rearrangement. This case illustrates the importance of integrating clinical, cytological, immunophenotypical, and molecular findings to reach a correct diagnosis. Diagn. Cytopathol. 2017;45:257-261. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Ectromelia virus accumulates less double-stranded RNA compared to vaccinia virus in BS-C-1 cells.

PubMed

Frey, Tiffany R; Lehmann, Michael H; Ryan, Colton M; Pizzorno, Marie C; Sutter, Gerd; Hersperger, Adam R

2017-09-01

Most orthopoxviruses, including vaccinia virus (VACV), contain genes in the E3L and K3L families. The protein products of these genes have been shown to combat PKR, a host defense pathway. Interestingly, ectromelia virus (ECTV) contains an E3L ortholog but does not possess an intact K3L gene. Here, we gained insight into how ECTV can still efficiently evade PKR despite lacking K3L. Relative to VACV, we found that ECTV-infected BS-C-1 cells accumulated considerably less double-stranded (ds) RNA, which was due to lower mRNA levels and less transcriptional read-through of some genes by ECTV. The abundance of dsRNA in VACV-infected cells, detected using a monoclonal antibody, was able to activate the RNase L pathway at late time points post-infection. Historically, the study of transcription by orthopoxviruses has largely focused on VACV as a model. Our data suggest that there could be more to learn by studying other members of this genus. Copyright © 2017 Elsevier Inc. All rights reserved.

Red blood cell membrane viscoelasticity, agglutination and zeta potential measurements with double optical tweezers

NASA Astrophysics Data System (ADS)

Fontes, Adriana; Fernandes, Heloise P.; Barjas-Castro, Maria L.; de Thomaz, André A.; de Ysasa Pozzo, Liliana; Barbosa, Luiz C.; Cesar, Carlos L.

2006-02-01

The red blood cell (RBC) viscoelastic membrane contains proteins and glycolproteins embedded in, or attached, to a fluid lipid bilayer and are negatively charged, which creates a repulsive electric (zeta) potential between the cells and prevents their aggregation in the blood stream. There are techniques, however, to decrease the zeta potential to allow cell agglutination which are the basis of most of the tests of antigen-antibody interactions in blood banks. This report shows the use of a double optical tweezers to measure RBC membrane viscosity, agglutination and zeta potential. In our technique one of the optical tweezers trap a silica bead that binds strongly to a RBC at the end of a RBCs rouleaux and, at the same time, acts as a pico-Newton force transducer, after calibration through its displacement from the equilibrium position. The other optical tweezers trap the RBC at the other end. To measure the membrane viscosity the optical force is measured as a function of the velocity between the RBCs. To measure the adhesion the tweezers are slowly displaced apart until the RBCs disagglutination happens. The RBC zeta potential is measured in two complimentary ways, by the force on the silica bead attached to a single RBC in response to an applied electric field, and the conventional way, by the measurement of terminal velocity of the RBC after released from the optical trap. These two measurements provide information about the RBC charges and, also, electrolytic solution properties. We believe this can improve the methods of diagnosis in blood banks.

DNA-incorporated 125I induces more than one double-strand break per decay in mammalian cells.

PubMed

Elmroth, Kecke; Stenerlöw, Bo

2005-04-01

The Auger-electron emitter 125I releases cascades of 20 electrons per decay that deposit a great amount of local energy, and for DNA-incorporated 125I, approximately one DNA double-strand break (DSB) is produced close to the decay site. To investigate the potential of 125I to induce additional DSBs within adjacent chromatin structures in mammalian cells, we applied DNA fragment-size analysis based on pulsed-field gel electrophoresis (PFGE) of hamster V79-379A cells exposed to DNA-incorporated 125IdU. After accumulation of decays at -70 degrees C in the presence of 10% DMSO, there was a non-random distribution of DNA fragments with an excess of fragments <0.5 Mbp and the measured yield was 1.6 DSBs/decay. However, since these experiments were performed under high scavenging conditions (DMSO) that reduce indirect effects, the yield in cells exposed to 125IdU under physiological conditions would most likely be even higher. In contrast, using a conventional low-resolution assay without measurement of smaller DNA fragments, the yield was close to one DSB/decay. We conclude that a large fraction of the DSBs induced by DNA-incorporated 125I are nonrandomly distributed and that significantly more than one DSB/decay is induced in an intact cell. Thus, in addition to DSBs produced close to the decay site, DSBs may also be induced within neighboring chromatin fibers, releasing smaller DNA fragments that are not detected by conventional DSB assays.

U-shaped, double-tapered, fiber-optic sensor for effective biofilm growth monitoring

PubMed Central

Zhong, Nianbing; Zhao, Mingfu; Li, Yishan

2016-01-01

To monitor biofilm growth on polydimethylsiloxane in a photobioreactor effectively, the biofilm cells and liquids were separated and measured using a sensor with two U-shaped, double-tapered, fiber-optic probes (Sen. and Ref. probes). The probes’ Au-coated hemispherical tips enabled double-pass evanescent field absorption. The Sen. probe sensed the cells and liquids inside the biofilm. The polyimide–silica hybrid-film-coated Ref. probe separated the liquids from the biofilm cells and analyzed the liquid concentration. The biofilm structure and active biomass were also examined to confirm the effectiveness of the measurement using a simulation model. The sensor was found to effectively respond to the biofilm growth in the adsorption through exponential phases at thicknesses of 0–536 μm. PMID:26977344

U-shaped, double-tapered, fiber-optic sensor for effective biofilm growth monitoring.

PubMed

Zhong, Nianbing; Zhao, Mingfu; Li, Yishan

2016-02-01

To monitor biofilm growth on polydimethylsiloxane in a photobioreactor effectively, the biofilm cells and liquids were separated and measured using a sensor with two U-shaped, double-tapered, fiber-optic probes (Sen. and Ref. probes). The probes' Au-coated hemispherical tips enabled double-pass evanescent field absorption. The Sen. probe sensed the cells and liquids inside the biofilm. The polyimide-silica hybrid-film-coated Ref. probe separated the liquids from the biofilm cells and analyzed the liquid concentration. The biofilm structure and active biomass were also examined to confirm the effectiveness of the measurement using a simulation model. The sensor was found to effectively respond to the biofilm growth in the adsorption through exponential phases at thicknesses of 0-536 μm.

Double aortic arch

MedlinePlus

Aortic arch anomaly; Double arch; Congenital heart defect - double aortic arch; Birth defect heart - double aortic arch ... aorta is a single arch that leaves the heart and moves leftward. In double aortic arch, some ...

DNA double-strand breaks in human induced pluripotent stem cell reprogramming and long-term in vitro culturing.

PubMed

Simara, Pavel; Tesarova, Lenka; Rehakova, Daniela; Matula, Pavel; Stejskal, Stanislav; Hampl, Ales; Koutna, Irena

2017-03-21

Human induced pluripotent stem cells (hiPSCs) play roles in both disease modelling and regenerative medicine. It is critical that the genomic integrity of the cells remains intact and that the DNA repair systems are fully functional. In this article, we focused on the detection of DNA double-strand breaks (DSBs) by phosphorylated histone H2AX (known as γH2AX) and p53-binding protein 1 (53BP1) in three distinct lines of hiPSCs, their source cells, and one line of human embryonic stem cells (hESCs). We measured spontaneously occurring DSBs throughout the process of fibroblast reprogramming and during long-term in vitro culturing. To assess the variations in the functionality of the DNA repair system among the samples, the number of DSBs induced by γ-irradiation and the decrease over time was analysed. The foci number was detected by fluorescence microscopy separately for the G1 and S/G2 cell cycle phases. We demonstrated that fibroblasts contained a low number of non-replication-related DSBs, while this number increased after reprogramming into hiPSCs and then decreased again after long-term in vitro passaging. The artificial induction of DSBs revealed that the repair mechanisms function well in the source cells and hiPSCs at low passages, but fail to recognize a substantial proportion of DSBs at high passages. Our observations suggest that cellular reprogramming increases the DSB number but that the repair mechanism functions well. However, after prolonged in vitro culturing of hiPSCs, the repair capacity decreases.

Depletion of pro-inflammatory CD161(+) double negative (CD3(+)CD4(-)CD8(-)) T cells in AIDS patients is ameliorated by expansion of the γδ T cell population.

PubMed

Singleterry, Will L; Henderson, Harold; Cruse, Julius M

2012-02-01

In this present investigation, flow cytometry was utilized to evaluate 13 healthy controls and 31 HIV-1 infected patients who had advanced to the AIDS stage of infection (CD4 count below 200 cells/mm(3)), for the expression of CD161 on CD3(+) double negative (DN) (CD3(+)CD4(-)CD8(-)) T cells, CD4(+) T cells, CD8(+) T cells and γδ T cells. The observed depletion of CD161(+) T cells from peripheral circulation was due primarily to the loss of CD4(+)CD161(+) T cells; as these cells represented 8.67±0.74% of the total healthy control peripheral T cell population, while the CD4(+)CD161(+) T cells of the AIDS group represented only 3.35±0.41% (p=<0.0001) of the total peripheral T cell population. We have also shown here that the DN T cell population was more than doubled in the AIDS group, with the DN T cell population expanding from 3.29±0.45% of the healthy control peripheral T cell population to 8.64±1.16% (p=0.0001) of the AIDS group peripheral T cell population. By evaluating the expression of CD161 on the surface of the DN T cells we showed that within the healthy control group, 47.4±4.99% of the DN T cells were positive for the expression of CD161, while only 26.4±3.54% (p=0.002) of the AIDS group's DN T cells expressed CD161. Despite CD161 expression being halved on the DN T cells of the AIDS group, when we compared the total peripheral T cell percentage of CD161(+) DN T cells between the healthy control group and the AIDS group, there was no statistical difference. Even though only 26.4% DN T cells within the AIDS group were positive for CD161(+), the overall DN T cell population had expanded to such an extent that there was no statistical difference between the groups with regard to CD161(+) DN T cells as a percentage of the total peripheral T cell population. Furthermore, we showed that within the DN T cell population, there was an approximate 2:1 ratio of γδ to αβ T cells, and this ratio was maintained in both the healthy control group and the

Visualizing double-stranded RNA distribution and dynamics in living cells by dsRNA binding-dependent fluorescence complementation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Xiaofei; College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, Zhejiang 310036; Deng, Ping

Double-stranded RNA (dsRNA) is an important type of RNA that plays essential roles in diverse cellular processes in eukaryotic organisms and a hallmark in infections by positive-sense RNA viruses. Currently, no in vivo technology has been developed for visualizing dsRNA in living cells. Here, we report a dsRNA binding-dependent fluorescence complementation (dRBFC) assay that can be used to efficiently monitor dsRNA distribution and dynamics in vivo. The system consists of two dsRNA-binding proteins, which are fused to the N- and C-terminal halves of the yellow fluorescent protein (YFP). Binding of the two fusion proteins to a common dsRNA brings themore » split YFP halves in close proximity, leading to the reconstitution of the fluorescence-competent structure and restoration of fluorescence. Using this technique, we were able to visualize the distribution and trafficking of the replicative RNA intermediates of positive-sense RNA viruses in living cells. - Highlights: • A live-cell imaging system was developed for visualizing dsRNA in vivo. • It uses dsRNA binding proteins fused with two halves of a fluorescent protein. • Binding to a common dsRNA enables the reporter to become fluorescent. • The system can efficiently monitor viral RNA replication in living cells.« less

Physics constraints on double-pulse LIA engineering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ekdahl, Carl August Jr.

2015-05-20

The options for advanced-radiography double-pulse linear induction accelerators (LIA) under consideration naturally fall into three categories that differ by the number of cells required. Since the two major physics issues, beam breakup (BBU) and corkscrew, are also dependent on the number of cells, it may be useful for the decision process to review the engineering consequences of beam physics constraints for each class. The LIAs can be categorized three different ways, and this report compares the different categories based upon the physics of their beams.

Substituted Quaternary Ammonium Salts Improve Low-Temperature Performance of Double-Layer Capacitors

NASA Technical Reports Server (NTRS)

Brandon, Erik J.; Smart, Marshall C.; West, William C.

2011-01-01

Double-layer capacitors are unique energy storage devices, capable of supporting large current pulses as well as a very high number of charging and discharging cycles. The performance of doublelayer capacitors is highly dependent on the nature of the electrolyte system used. Many applications, including for electric and fuel cell vehicles, back-up diesel generators, wind generator pitch control back-up power systems, environmental and structural distributed sensors, and spacecraft avionics, can potentially benefit from the use of double-layer capacitors with lower equivalent series resistances (ESRs) over wider temperature limits. Higher ESRs result in decreased power output, which is a particular problem at lower temperatures. Commercially available cells are typically rated for operation down to only 40 C. Previous briefs [for example, Low Temperature Supercapacitors (NPO-44386), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), p. 32, and Supercapacitor Electrolyte Solvents With Liquid Range Below 80 C (NPO-44855), NASA Tech Briefs, Vol. 34, No. 1 (January 2010), p. 44] discussed the use of electrolytes that employed low-melting-point co-solvents to depress the freezing point of traditional acetonitrile-based electrolytes. Using these modified electrolyte formulations can extend the low-temperature operational limit of double-layer capacitors beyond that of commercially available cells. This previous work has shown that although the measured capacitance is relatively insensitive to temperature, the ESR can rise rapidly at low temperatures, due to decreased electrolyte conductance within the pores of the high surface- area carbon electrodes. Most of these advanced electrolyte systems featured tetraethylammonium tetrafluoroborate (TEATFB) as the salt. More recent work at JPL indicates the use of the asymmetric quaternary ammonium salt triethylmethylammonium tetrafluoroborate (TEMATFB) or spiro-(l,l')-bipyrrolidium tetrafluoroborate (SBPBF4) in a 1:1 by volume solvent

[Double fertilization in flowering plants: 1898-2008].

PubMed

Kordium, E L

2008-01-01

A short review of the results of investigations in the field of plant embryology in vivo and in vitro which are directly connected with the discovery of double fertilization in flowering plants by S.G. Navashin is presented. These results have been obtained by using the methods of electron and fluorescence microscopy, cytophotometry, cultures of isolated ovules, sperms, eggs, and embryo sac central cells. The question on an origin of the female gametophyte of flowering plants, double fertilization, and endosperm are discussed. It is emphasized that the progress in this field is connected mostly with the study of molecular processes which control the development and functioning of a female gametophyte and sporophyte at the early stages of ontogenesis.

Double Layers in Astrophysics

NASA Technical Reports Server (NTRS)

Williams, Alton C. (Editor); Moorehead, Tauna W. (Editor)

1987-01-01

Topics addressed include: laboratory double layers; ion-acoustic double layers; pumping potential wells; ion phase-space vortices; weak double layers; electric fields and double layers in plasmas; auroral double layers; double layer formation in a plasma; beamed emission from gamma-ray burst source; double layers and extragalactic jets; and electric potential between plasma sheet clouds.

Characterization of glioma stem cells through multiple stem cell markers and their specific sensitization to double-strand break-inducing agents by pharmacological inhibition of ataxia telangiectasia mutated protein.

PubMed

Raso, Alessandro; Vecchio, Donatella; Cappelli, Enrico; Ropolo, Monica; Poggi, Alessandro; Nozza, Paolo; Biassoni, Roberto; Mascelli, Samantha; Capra, Valeria; Kalfas, Fotios; Severi, Paolo; Frosina, Guido

2012-09-01

Previous studies have shown that tumor-driving glioma stem cells (GSC) may promote radio-resistance by constitutive activation of the DNA damage response started by the ataxia telangiectasia mutated (ATM) protein. We have investigated whether GSC may be specifically sensitized to ionizing radiation by inhibiting the DNA damage response. Two grade IV glioma cell lines (BORRU and DR177) were characterized for a number of immunocytochemical, karyotypic, proliferative and differentiative parameters. In particular, the expression of a panel of nine stem cell markers was quantified by reverse transcription-polymerase chain reaction (RT-PCR) and flow cytometry. Overall, BORRU and DR177 displayed pronounced and poor stem phenotypes, respectively. In order to improve the therapeutic efficacy of radiation on GSC, the cells were preincubated with a nontoxic concentration of the ATM inhibitors KU-55933 and KU-60019 and then irradiated. BORRU cells were sensitized to radiation and radio-mimetic chemicals by ATM inhibitors whereas DR177 were protected under the same conditions. No sensitization was observed after cell differentiation or to drugs unable to induce double-strand breaks (DSB), indicating that ATM inhibitors specifically sensitize glioma cells possessing stem phenotype to DSB-inducing agents. In conclusion, pharmacological inhibition of ATM may specifically sensitize GSC to DSB-inducing agents while sparing nonstem cells. © 2012 The Authors; Brain Pathology © 2012 International Society of Neuropathology.

DNA double strand break (DSB) induction and cell survival in iodine-enhanced computed tomography (CT)

NASA Astrophysics Data System (ADS)

Streitmatter, Seth W.; Stewart, Robert D.; Jenkins, Peter A.; Jevremovic, Tatjana

2017-08-01

A multi-scale Monte Carlo model is proposed to assess the dosimetric and biological impact of iodine-based contrast agents commonly used in computed tomography. As presented, the model integrates the general purpose MCNP6 code system for larger-scale radiation transport and dose assessment with the Monte Carlo damage simulation to determine the sub-cellular characteristics and spatial distribution of initial DNA damage. The repair-misrepair-fixation model is then used to relate DNA double strand break (DSB) induction to reproductive cell death. Comparisons of measured and modeled changes in reproductive cell survival for ultrasoft characteristic k-shell x-rays (0.25-4.55 keV) up to orthovoltage (200-500 kVp) x-rays indicate that the relative biological effectiveness (RBE) for DSB induction is within a few percent of the RBE for cell survival. Because of the very short range of secondary electrons produced by low energy x-ray interactions with contrast agents, the concentration and subcellular distribution of iodine within and near cellular targets have a significant impact on the estimated absorbed dose and number of DSB produced in the cell nucleus. For some plausible models of the cell-level distribution of contrast agent, the model predicts an increase in RBE-weighted dose (RWD) for the endpoint of DSB induction of 1.22-1.40 for a 5-10 mg ml-1 iodine concentration in blood compared to an RWD increase of 1.07  ±  0.19 from a recent clinical trial. The modeled RWD of 2.58  ±  0.03 is also in good agreement with the measured RWD of 2.3  ±  0.5 for an iodine concentration of 50 mg ml-1 relative to no iodine. The good agreement between modeled and measured DSB and cell survival estimates provides some confidence that the presented model can be used to accurately assess biological dose for other concentrations of the same or different contrast agents.

Studying red blood cell agglutination by measuring electrical and mechanical properties with a double optical tweezers

NASA Astrophysics Data System (ADS)

Fontes, Adriana; Fernandes, Heloise P.; de Thomaz, André A.; Barbosa, Luiz C.; Barjas-Castro, Maria L.; Cesar, Carlos L.

2007-07-01

The red blood cell (RBC) viscoelastic membrane contains proteins and glycolproteins embedded in, or attached, to a fluid lipid bilayer and are negatively charged, which creates a repulsive electric (zeta) potential between the cells and prevents their aggregation in the blood stream. The basis of the immunohematologic tests is the interaction between antigens and antibodies that causes hemagglutination. The identification of antibodies and antigens is of fundamental importance for the transfusional routine. This agglutination is induced by decreasing the zeta-potential through the introduction of artificial potential substances. This report proposes the use of the optical tweezers to measure the membrane viscosity, the cell adhesion, the zeta-potential and the size of the double layer of charges (CLC) formed around the cell in an electrolytic solution. The adhesion was quantified by slowly displacing two RBCs apart until the disagglutination. The CLC was measured using the force on the bead attached to a single RBC in response to an applied voltage. The zeta-potential was obtained by measuring the terminal velocity after releasing the RBC from the optical trap at the last applied voltage. For the membrane viscosity experiment, we trapped a bead attached to RBCs and measured the force to slide one RBC over the other as a function of the relative velocity. After we tested the methodology, we performed measurements using antibody and potential substances. We observed that this experiment can provide information about cell agglutination that helps to improve the tests usually performed in blood banks. We also believe that this methodology can be applied for measurements of zeta-potentials in other kind of samples.

Therapeutic synergy between tigecycline and venetoclax in a preclinical model of MYC/BCL2 double-hit B cell lymphoma.

PubMed

Ravà, Micol; D'Andrea, Aleco; Nicoli, Paola; Gritti, Ilaria; Donati, Giulio; Doni, Mirko; Giorgio, Marco; Olivero, Daniela; Amati, Bruno

2018-01-31

High-grade B cell lymphomas with concurrent activation of the MYC and BCL2 oncogenes, also known as double-hit lymphomas (DHL), show dismal prognosis with current therapies. MYC activation sensitizes cells to inhibition of mitochondrial translation by the antibiotic tigecycline, and treatment with this compound provides a therapeutic window in a mouse model of MYC -driven lymphoma. We now addressed the utility of this antibiotic for treatment of DHL. BCL2 activation in mouse Eμ- myc lymphomas antagonized tigecycline-induced cell death, which was specifically restored by combined treatment with the BCL2 inhibitor venetoclax. In line with these findings, tigecycline and two related antibiotics, tetracycline and doxycycline, synergized with venetoclax in killing human MYC/BCL2 DHL cells. Treatment of mice engrafted with either DHL cell lines or a patient-derived xenograft revealed strong antitumoral effects of the tigecycline/venetoclax combination, including long-term tumor eradication with one of the cell lines. This drug combination also had the potential to cooperate with rituximab, a component of current front-line regimens. Venetoclax and tigecycline are currently in the clinic with distinct indications: Our preclinical results warrant the repurposing of these drugs for combinatorial treatment of DHL. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Mitochondrial DNA repairs double-strand breaks in yeast chromosomes.

PubMed

Ricchetti, M; Fairhead, C; Dujon, B

1999-11-04

The endosymbiotic theory for the origin of eukaryotic cells proposes that genetic information can be transferred from mitochondria to the nucleus of a cell, and genes that are probably of mitochondrial origin have been found in nuclear chromosomes. Occasionally, short or rearranged sequences homologous to mitochondrial DNA are seen in the chromosomes of different organisms including yeast, plants and humans. Here we report a mechanism by which fragments of mitochondrial DNA, in single or tandem array, are transferred to yeast chromosomes under natural conditions during the repair of double-strand breaks in haploid mitotic cells. These repair insertions originate from noncontiguous regions of the mitochondrial genome. Our analysis of the Saccharomyces cerevisiae mitochondrial genome indicates that the yeast nuclear genome does indeed contain several short sequences of mitochondrial origin which are similar in size and composition to those that repair double-strand breaks. These sequences are located predominantly in non-coding regions of the chromosomes, frequently in the vicinity of retrotransposon long terminal repeats, and appear as recent integration events. Thus, colonization of the yeast genome by mitochondrial DNA is an ongoing process.

Widely-duration-tunable nanosecond pulse Nd:YVO4 laser based on double Pockels cells

NASA Astrophysics Data System (ADS)

He, Li-Jiao; Liu, Ke; Bo, Yong; Wang, Xiao-Jun; Yang, Jing; Liu, Zhao; Zong, Qing-Shuang; Peng, Qin-Jun; Cui, Da-Fu; Xu, Zu-Yan

2018-05-01

The development of duration-tunable pulse lasers with constant output power is important for scientific research and materials processing. We present a widely-duration-tunable nanosecond (ns) pulse Nd:YVO4 laser based on double Pockels cells (PCs), i.e. inserting an extra PC into a conventional electro-optic Q-switched cavity dumped laser resonator. Under the absorbed pump power of 24.9 W, the pulse duration is adjustable from 31.9 ns to 5.9 ns by changing the amplitude of the high voltage on the inserted PC from 1100 V to 4400 V at the pulse repetition rate of 10 kHz. The corresponding average output power is almost entirely maintained in the range of 3.5–4.1 W. This represents more than three times increase in pulse duration tunable regime and average power compared to previously reported results for duration-tunable ns lasers. The laser beam quality factor was measured to be M 2  <  1.18.

Improved opto-electronic properties of silicon heterojunction solar cells with SiO x /Tungsten-doped indium oxide double anti-reflective coatings

NASA Astrophysics Data System (ADS)

Yu, Jian; Zhou, Jie; Bian, Jiantao; Zhang, Liping; Liu, Yucheng; Shi, Jianhua; Meng, Fanying; Liu, Jinning; Liu, Zhengxin

2017-08-01

Amorphous SiO x was prepared by plasma enhanced chemical vapor deposition (PECVD) to form SiO x /tungsten-doped indium oxide (IWO) double anti-reflective coatings for silicon heterojunction (SHJ) solar cell. The sheet resistance of SiO x /IWO stacks decreases due to plasma treatment during deposition process, which means thinner IWO film would be deposited for better optical response. However, the comparisons of three anti-reflective coating (ARC) structures reveal that SiO x film limits carier transport and the path of IWO-SiO x -Ag structure is non-conductive. The decrease of sheet resistance is defined as pseudo conductivity. IWO film capping with SiO x allows observably reduced reflectance and better response in 300-400 and 600-1200 nm wavelength ranges. Compared with IWO single ARC, the average reflection is reduced by 1.65% with 70 nm SiO x /80 nm IWO double anti-reflective coatings (DARCs) in 500-1200 nm wavelength range, leading to growing external quantum efficiency response, short circuit current density (J sc), and efficiency. After well optimization of SiO x /IWO stacks, an impressive efficiency of 23.08% is obtained with high J sc and without compromising open circuit voltage (V oc) and fill factor. SiO x /IWO DARCs provide better anti-reflective properties over a broad range of wavelength, showing promising application for SHJ solar cells.

Identification of defective illegitimate recombinational repair of oxidatively-induced DNA double-strand breaks in ataxia-telangiectasia cells

NASA Technical Reports Server (NTRS)

Dar, M. E.; Winters, T. A.; Jorgensen, T. J.

1997-01-01

Ataxia-telangiectasia (A-T) is an autosomal-recessive lethal human disease. Homozygotes suffer from a number of neurological disorders, as well as very high cancer incidence. Heterozygotes may also have a higher than normal risk of cancer, particularly for the breast. The gene responsible for the disease (ATM) has been cloned, but its role in mechanisms of the disease remain unknown. Cellular A-T phenotypes, such as radiosensitivity and genomic instability, suggest that a deficiency in the repair of DNA double-strand breaks (DSBs) may be the primary defect; however, overall levels of DSB rejoining appear normal. We used the shuttle vector, pZ189, containing an oxidatively-induced DSB, to compare the integrity of DSB rejoining in one normal and two A-T fibroblast cells lines. Mutation frequencies were two-fold higher in A-T cells, and the mutational spectrum was different. The majority of the mutations found in all three cell lines were deletions (44-63%). The DNA sequence analysis indicated that 17 of the 17 plasmids with deletion mutations in normal cells occurred between short direct-repeat sequences (removing one of the repeats plus the intervening sequences), implicating illegitimate recombination in DSB rejoining. The combined data from both A-T cell lines showed that 21 of 24 deletions did not involve direct-repeats sequences, implicating a defect in the illegitimate recombination pathway. These findings suggest that the A-T gene product may either directly participate in illegitimate recombination or modulate the pathway. Regardless, this defect is likely to be important to a mechanistic understanding of this lethal disease.

Layered double hydroxide-enhanced luminescence in a Fenton-like system for selective sensing of cobalt in Hela cells

NASA Astrophysics Data System (ADS)

Yu, Mei; Yuan, Zhiqin; Lu, Chao

2017-09-01

This work presented a facile and eco-friendly method for the determination of cobalt ions (Co(II)) in living cells based on layered double hydroxides (Mg-Al CO3-LDHs) enhanced chemiluminescence (CL) emission of a Co(II)-hydrogen peroxide-sodium hydroxide system. The enhanced CL emission was attributed to the large specific surface area of Mg-Al CO3-LDHs, which facilitates the generation of an excited-stated intermediate. The proposed method displayed high selectivity toward Co(II) over other metal ions. Under the optimal conditions, the increased CL intensity showed a linear response versus Co(II) concentration in the range of 5.0-1000 nM with a detection limit of 3.7 nM (S/N = 3). The relative standard deviation for nine repeated measurements of 100 nM Co(II) was 3.2%. Furthermore, the proposed method was successfully applied to detect Co(II) in living cell samples, and the results were agreed with those obtained by the standard ICP-MS method.

Synthesising methods of layered double hydroxides and its use in the fabrication of dye Sensitised solar cell (DSSC): A short review

NASA Astrophysics Data System (ADS)

George, Giphin; Saravanakumar, M. P.

2017-11-01

The layered double hydroxides (LDH) which are anionic clay substances comprising of stacked cationic layers and interlayer anions. The cationic sheets contain octahedral structure consisting the divalent and trivalent ions in the center and hydroxyl bunches in the corners, gathered by three bonding with the neighbouring octahedra on every side of the layer. The ratio between the quantity of cations and OH- ions is 2:1, so a positive charge shows up on the layer because of the presence of trivalent cations. The interlayer space gives the compensation anions and water molecules, assuring a balanced out layered structure. The LDH materials were successfully synthesised from magnesium, aluminium, zinc and chromium chloride salts utilizing the co-precipitation technique. A Zn-Al LDH was researched as a potential sorbent material. This article reviews the recent advances in the preparation and intercalation of layered double hydroxides and its application in the fabrication of Dye Sensitized Solar Cell (DSSC).

Double mutation of cell wall proteins CspB and PBP1a increases secretion of the antibody Fab fragment from Corynebacterium glutamicum

PubMed Central

2014-01-01

Background Among other advantages, recombinant antibody-binding fragments (Fabs) hold great clinical and commercial potential, owing to their efficient tissue penetration compared to that of full-length IgGs. Although production of recombinant Fab using microbial expression systems has been reported, yields of active Fab have not been satisfactory. We recently developed the Corynebacterium glutamicum protein expression system (CORYNEX®) and demonstrated improved yield and purity for some applications, although the system has not been applied to Fab production. Results The Fab fragment of human anti-HER2 was successfully secreted by the CORYNEX® system using the conventional C. glutamicum strain YDK010, but the productivity was very low. To improve the secretion efficiency, we investigated the effects of deleting cell wall-related genes. Fab secretion was increased 5.2 times by deletion of pbp1a, encoding one of the penicillin-binding proteins (PBP1a), mediating cell wall peptidoglycan (PG) synthesis. However, this Δpbp1a mutation did not improve Fab secretion in the wild-type ATCC13869 strain. Because YDK010 carries a mutation in the cspB gene encoding a surface (S)-layer protein, we evaluated the effect of ΔcspB mutation on Fab secretion from ATCC13869. The Δpbp1a mutation showed a positive effect on Fab secretion only in combination with the ΔcspB mutation. The ΔcspBΔpbp1a double mutant showed much greater sensitivity to lysozyme than either single mutant or the wild-type strain, suggesting that these mutations reduced cell wall resistance to protein secretion. Conclusion There are at least two crucial permeability barriers to Fab secretion in the cell surface structure of C. glutamicum, the PG layer, and the S-layer. The ΔcspBΔpbp1a double mutant allows efficient Fab production using the CORYNEX® system. PMID:24731213

Aggressive B cell Lymphoma: Optimal Therapy for MYC-positive, Double-Hit, and Triple-Hit DLBCL.

PubMed

Dunleavy, Kieron

2015-12-01

Approximately 10% of cases of diffuse large B cell lymphoma (DLBCL) harbor a MYC rearrangement and this has been associated with an inferior outcome following standard therapy across many different studies. Double-hit and triple-hit lymphomas harbor concurrent rearrangements of MYC and BCL2 and/or BCL6 and are also associated with a very aggressive course and poor clinical outcome. It is unclear and there is lack of consensus on how these diseases should be approached therapeutically. They are characterized typically by high tumor proliferation and likely require Burkitt lymphoma-type strategies and several retrospective studies suggest that more intensive approaches than rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) may be beneficial. One challenge in this respect is that most patients with these diseases are older than 60 years and generally have poor tolerability of regimens typically used in Burkitt lymphoma. Dose-adjusted EPOCH-R is an alternative effective immunochemotherapy platform for DLBCL and is effective in Burkitt lymphoma, and retrospective studies suggest that it is effective and feasible in patients with DLBCL that harbors a MYC rearrangement with or without a BCL-2 translocation (double-hit). A multicenter study of this approach in MYC-rearranged DLBCL is ongoing and preliminary results are very encouraging. There is a lack of consensus on the role of consolidation stem cell transplantation in patients who achieve a good response to initial therapy but at this point in time, no (retrospective) studies have demonstrated any benefit. These diseases are also associated with a high rate of CNS involvement and progression and checking for cerebrospinal fluid by cytology and flow cytometry at initial diagnosis should be considered. In summary, based on retrospective data and preliminary prospective data (as more mature data is awaited), while Burkitt-type regimens may be feasible in young patients, DA-EPOCH-R is a

Modelling the balance between quiescence and cell death in normal and tumour cell populations.

PubMed

Spinelli, Lorenzo; Torricelli, Alessandro; Ubezio, Paolo; Basse, Britta

2006-08-01

When considering either human adult tissues (in vivo) or cell cultures (in vitro), cell number is regulated by the relationship between quiescent cells, proliferating cells, cell death and other controls of cell cycle duration. By formulating a mathematical description we see that even small alterations of this relationship may cause a non-growing population to start growing with doubling times characteristic of human tumours. Our model consists of two age structured partial differential equations for the proliferating and quiescent cell compartments. Model parameters are death rates from and transition rates between these compartments. The partial differential equations can be solved for the steady-age distributions, giving the distribution of the cells through the cell cycle, dependent on specific model parameter values. Appropriate formulas can then be derived for various population characteristic quantities such as labelling index, proliferation fraction, doubling time and potential doubling time of the cell population. Such characteristic quantities can be estimated experimentally, although with decreasing precision from in vitro, to in vivo experimental systems and to the clinic. The model can be used to investigate the effects of a single alteration of either quiescence or cell death control on the growth of the whole population and the non-trivial dependence of the doubling time and other observable quantities on particular underlying cell cycle scenarios of death and quiescence. The model indicates that tumour evolution in vivo is a sequence of steady-states, each characterised by particular death and quiescence rate functions. We suggest that a key passage of carcinogenesis is a loss of the communication between quiescence, death and cell cycle machineries, causing a defect in their precise, cell cycle dependent relationship.

Somatic mosaicism containing double mutations in PTCH1 revealed by generation of induced pluripotent stem cells from nevoid basal cell carcinoma syndrome.

PubMed

Ikemoto, Yu; Takayama, Yoshinaga; Fujii, Katsunori; Masuda, Mokuri; Kato, Chise; Hatsuse, Hiromi; Fujitani, Kazuko; Nagao, Kazuaki; Kameyama, Kohzoh; Ikehara, Hajime; Toyoda, Masashi; Umezawa, Akihiro; Miyashita, Toshiyuki

2017-08-01

Nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterised by developmental defects and tumorigenesis, such as medulloblastomas and basal cell carcinomas, caused by mutations of the patched-1 ( PTCH1 ) gene. In this article, we seek to demonstrate a mosaicism containing double mutations in PTCH1 in an individual with NBCCS. A de novo germline mutation of PTCH1 (c.272delG) was detected in a 31-year-old woman with NBCCS. Gene analysis of two out of four induced pluripotent stem cell (iPSC) clones established from the patient unexpectedly revealed an additional mutation, c.274delT. Deep sequencing confirmed a low-prevalence somatic mutation (5.5%-15.6% depending on the tissue) identical to the one found in iPSC clones. This is the first case of mosaicism unequivocally demonstrated in NBCCS. Furthermore, the mosaicism is unique in that the patient carries one normal and two mutant alleles. Because these mutations are located in close proximity, reversion error is likely to be involved in this event rather than a spontaneous mutation. In addition, this study indicates that gene analysis of iPSC clones can contribute to the detection of mosaicism containing a minor population carrying a second mutation. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Depletion of tyrosyl DNA phosphodiesterase 2 activity enhances etoposide-mediated double-strand break formation and cell killing.

PubMed

Kont, Yasemin Saygideger; Dutta, Arijit; Mallisetty, Apurva; Mathew, Jeena; Minas, Tsion; Kraus, Christina; Dhopeshwarkar, Priyanka; Kallakury, Bhaskar; Mitra, Sankar; Üren, Aykut; Adhikari, Sanjay

2016-07-01

DNA topoisomerase 2 (Top2) poisons, including common anticancer drugs etoposide and doxorubicin kill cancer cells by stabilizing covalent Top2-tyrosyl-DNA 5'-phosphodiester adducts and DNA double-strand breaks (DSBs). Proteolytic degradation of the covalently attached Top2 leaves a 5'-tyrosylated blocked termini which is removed by tyrosyl DNA phosphodiesterase 2 (TDP2), prior to DSB repair through non-homologous end joining (NHEJ). Thus, TDP2 confers resistance of tumor cells to Top2-poisons by repairing such covalent DNA-protein adducts, and its pharmacological inhibition could enhance the efficacy of Top2-poisons. We discovered NSC111041, a selective inhibitor of TDP2, by optimizing a high throughput screening (HTS) assay for TDP2's 5'-tyrosyl phosphodiesterase activity and subsequent validation studies. We found that NSC111041 inhibits TDP2's binding to DNA without getting intercalated into DNA and enhanced etoposide's cytotoxicity synergistically in TDP2-expressing cells but not in TDP2 depleted cells. Furthermore, NSC111041 enhanced formation of etoposide-induced γ-H2AX foci presumably by affecting DSB repair. Immuno-histochemical analysis showed higher TDP2 expression in a sub-set of different type of tumor tissues. These findings underscore the feasibility of clinical use of suitable TDP2 inhibitors in adjuvant therapy with Top2-poisons for a sub-set of cancer patients with high TDP2 expression. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of Cationic Microbubble Carrying CD/TK Double Suicide Gene and αVβ3 Integrin Antibody in Human Hepatocellular Carcinoma HepG2 Cells.

PubMed

Li, Jiale; Zhou, Ping; Li, Lan; Zhang, Yan; Shao, Yang; Tang, Li; Tian, Shuangming

2016-01-01

Hepatocellular carcinoma (HCC), mostly derived from hepatitis or cirrhosisis, is one of the most common types of liver cancer. T-cell mediated immune response elicited by CD/TK double suicide gene has shown a substantial antitumor effect in HCC. Integrin αVβ3 over expresssion has been suggested to regulate the biology behavior of HCC. In this study, we investigated the strategy of incorporating CD/TK double suicide gene and anti-αVβ3 integrin monoclonal antibodies into cationic microbubbles (CMBsαvβ3), and evaluated its killing effect in HCC cells. To improve the transfection efficiency of targeted CD/TK double suicide gene, we adopted cationic microbubbles (CMBs), a cationic delivery agent with enhanced DNA-carrying capacity. The ultrasound and high speed shearing method was used to prepare the non-targeting cationic microbubbles (CMBs). Using the biotin-avidin bridge method, αVβ3 integrin antibody was conjugated to CMBs, and CMBsαvβ3 was generated to specifically target to HepG2 cells. The morphology and physicochemical properties of the CMBsαvβ3 was detected by optical microscope and zeta detector. The conjugation of plasmid and the antibody in CMBsαvβ3 were examined by immunofluorescent microscopy and flow cytometry. The binding capacities of CMBsαvβ3 and CMBs to HCC HepG2 and normal L-02 cells were compared using rosette formation assay. To detect EGFP fluorescence and examine the transfection efficiencies of CMBsαvβ3 and CMBs in HCC cells, fluorescence microscope and contrast-enhanced sonography were adopted. mRNA and protein level of CD/TK gene were detected by RT-PCR and Western blot, respectively. To evaluate the anti-tumor effect of CMBsαvβ3, HCC cells with CMBsαvβ3 were exposed to 5-flurocytosine / ganciclovir (5-FC/GCV). Then, cell cycle distribution after treatment were detected by PI staining and flow cytometry. Apoptotic cells death were detected by optical microscope and assessed by MTT assay and TUNEL-staining assay. CMBs

On the origin and elimination of macroscopic defects in MBE films

NASA Astrophysics Data System (ADS)

Wood, C. E. C.; Rathbun, L.; Ohno, H.; DeSimone, D.

1981-02-01

Spitting of group III metal droplets from Knudsen type effusion cells has been found culpable for a genre of problematical macroscopic surface topographical defects observed in the growth of semiconductor films by molecular beam epitaxy. Successful precautions are described which virtually eliminate the problem.

Deletion of Cytoplasmic Double-Stranded RNA Sensors Does Not Uncover Viral Small Interfering RNA Production in Human Cells.

PubMed

Schuster, Susan; Tholen, Lotte E; Overheul, Gijs J; van Kuppeveld, Frank J M; van Rij, Ronald P

2017-01-01

Antiviral immunity in insects and plants is mediated by the RNA interference (RNAi) pathway in which viral long double-stranded RNA (dsRNA) is processed into small interfering RNAs (siRNAs) by Dicer enzymes. Although this pathway is evolutionarily conserved, its involvement in antiviral defense in mammals is the subject of debate. In vertebrates, recognition of viral RNA induces a sophisticated type I interferon (IFN)-based immune response, and it has been proposed that this response masks or inhibits antiviral RNAi. To test this hypothesis, we analyzed viral small RNA production in differentiated cells deficient in the cytoplasmic RNA sensors RIG-I and MDA5. We did not detect 22-nucleotide (nt) viral siRNAs upon infection with three different positive-sense RNA viruses. Our data suggest that the depletion of cytoplasmic RIG-I-like sensors is not sufficient to uncover viral siRNAs in differentiated cells. IMPORTANCE The contribution of the RNA interference (RNAi) pathway in antiviral immunity in vertebrates has been widely debated. It has been proposed that RNAi possesses antiviral activity in mammalian systems but that its antiviral effect is masked by the potent antiviral interferon response in differentiated mammalian cells. In this study, we show that inactivation of the interferon response is not sufficient to uncover antiviral activity of RNAi in human epithelial cells infected with three wild-type positive-sense RNA viruses.

Benzothiadiazole-based polymer for single and double junction solar cells with high open circuit voltage.

PubMed

Venkatesan, Swaminathan; Ngo, Evan C; Chen, Qiliang; Dubey, Ashish; Mohammad, Lal; Adhikari, Nirmal; Mitul, Abu Farzan; Qiao, Qiquan

2014-06-21

Single and double junction solar cells with high open circuit voltage were fabricated using poly{thiophene-2,5-diyl-alt-[5,6-bis(dodecyloxy)benzo[c][1,2,5]thiadiazole]-4,7-diyl} (PBT-T1) blended with fullerene derivatives in different weight ratios. The role of fullerene loading on structural and morphological changes was investigated using atomic force microscopy (AFM) and X-ray diffraction (XRD). The XRD and AFM measurements showed that a higher fullerene mixing ratio led to breaking of inter-chain packing and hence resulted in smaller disordered polymer domains. When the PBT-T1:PC60BM weight ratio was 1 : 1, the polymer retained its structural order; however, large aggregated domains formed, leading to poor device performance due to low fill factor and short circuit current density. When the ratio was increased to 1 : 2 and then 1 : 3, smaller amorphous domains were observed, which improved photovoltaic performance. The 1 : 2 blending ratio was optimal due to adequate charge transport pathways giving rise to moderate short circuit current density and fill factor. Adding 1,8-diiodooctane (DIO) additive into the 1 : 2 blend films further improved both the short circuit current density and fill factor, leading to an increased efficiency to 4.5% with PC60BM and 5.65% with PC70BM. These single junction solar cells exhibited a high open circuit voltage at ∼ 0.9 V. Photo-charge extraction by linearly increasing voltage (Photo-CELIV) measurements showed the highest charge carrier mobility in the 1 : 2 film among the three ratios, which was further enhanced by introducing the DIO. The Photo-CELIV measurements with varying delay times showed significantly higher extracted charge carrier density for cells processed with DIO. Tandem devices using P3HT:IC60BA as bottom cell and PBT-T1:PC60BM as top cell exhibited a high open circuit voltage of 1.62 V with 5.2% power conversion efficiency.

Vinyl Monomers Double as UV Stabilizers: 179th ACS Meeting Houston.

ERIC Educational Resources Information Center

Chemical and Engineering News, 1980

1980-01-01

Synthesis and polymerization of vinyl monomers that double as stabilizers against degradation of plastics by ultraviolet light has been accomplished. Potential applications include protection of photovoltaic cells in solar power plants. (Author/RE)

Chromosome doubling method

DOEpatents

Kato, Akio

2006-11-14

The invention provides methods for chromosome doubling in plants. The technique overcomes the low yields of doubled progeny associated with the use of prior techniques for doubling chromosomes in plants such as grasses. The technique can be used in large scale applications and has been demonstrated to be highly effective in maize. Following treatment in accordance with the invention, plants remain amenable to self fertilization, thereby allowing the efficient isolation of doubled progeny plants.

Layered double hydroxide nanoparticles promote self-renewal of mouse embryonic stem cells through the PI3K signaling pathway

NASA Astrophysics Data System (ADS)

Wu, Youjun; Zhu, Rongrong; Zhou, Yang; Zhang, Jun; Wang, Wenrui; Sun, Xiaoyu; Wu, Xianzheng; Cheng, Liming; Zhang, Jing; Wang, Shilong

2015-06-01

Embryonic stem cells (ESCs) hold great potential for regenerative medicine due to their two unique characteristics: self-renewal and pluripotency. Several groups of nanoparticles have shown promising applications in directing the stem cell fate. Herein, we investigated the cellular effects of layered double hydroxide nanoparticles (LDH NPs) on mouse ESCs (mESCs) and the associated molecular mechanisms. Mg-Al-LDH NPs with an average diameter of ~100 nm were prepared by hydrothermal methods. To determine the influences of LDH NPs on mESCs, cellular cytotoxicity, self-renewal, differentiation potential, and the possible signaling pathways were explored. Evaluation of cell viability, lactate dehydrogenase release, ROS generation and apoptosis demonstrated the low cytotoxicity of LDH NPs. The alkaline phosphatase activity and the expression of pluripotency genes in mESCs were examined, which indicated that exposure to LDH NPs could support self-renewal and inhibit spontaneous differentiation of mESCs under feeder-free culture conditions. The self-renewal promotion was further proved to be independent of the leukemia inhibitory factor (LIF). Furthermore, cells treated with LDH NPs maintained the potential to differentiate into all three germ layers both in vitro and in vivo through formation of embryoid bodies and teratomas. In addition, we observed that LDH NPs initiated the activation of the PI3K/Akt pathway, while treatment with the PI3K inhibitor LY294002 could block the effects of LDH NPs on mESCs. The results confirmed that the promotion of self-renewal by LDH NPs was associated with activation of the PI3K/Akt signaling pathway. Altogether, our studies identified a new role of LDH NPs in maintaining self-renewal of mouse ES cells which could potentially be applied in stem cell research.Embryonic stem cells (ESCs) hold great potential for regenerative medicine due to their two unique characteristics: self-renewal and pluripotency. Several groups of nanoparticles

Circulating anti-double-stranded DNA antibody-secreting cells in patients with systemic lupus erythematosus: a novel biomarker for disease activity.

PubMed

Hanaoka, H; Okazaki, Y; Satoh, T; Kaneko, Y; Yasuoka, H; Seta, N; Kuwana, M

2012-10-01

Antibodies against double-stranded DNA (dsDNA) are widely used to diagnose systemic lupus erythematosus (SLE) and evaluate its activity in patients. This study was undertaken to examine the clinical utility of circulating anti-dsDNA antibody-secreting cells for evaluating SLE patients. Anti-dsDNA antibody-secreting cells quantified using an enzyme-linked immunospot assay were detected in the spleen, bone marrow and peripheral blood from MRL/lpr but not in control BALB/c mice. Circulating anti-dsDNA antibody-secreting cells were detected in 29 (22%) of 130 patients with SLE, but in none of 49 with non-SLE connective-tissue disease or 18 healthy controls. The presence of circulating anti-dsDNA antibody-secreting cells was associated with persistent proteinuria, high SLE disease activity index and systemic lupus activity measures, and a high serum anti-dsDNA antibody titre measured with an enzyme-linked immunosorbent assay. The positive predictive value for active disease was 48% for circulating anti-dsDNA antibody-secreting cells versus 17% for serum anti-dsDNA antibodies. A prospective cohort of patients with circulating anti-dsDNA antibodies and inactive SLE showed that the cumulative disease flare-free rate was significantly lower in patients with than without circulating anti-dsDNA antibody-secreting cells (p < 0.001). Circulating anti-dsDNA antibody-secreting cells are a useful biomarker for assessing disease activity in SLE patients.

Hydrodynamically induced fluid transfer and non-convective double-diffusion in microgravity sliding solvent diffusion cells

NASA Technical Reports Server (NTRS)

Pollmann, Konrad W.; Stodieck, Louis S.; Luttges, Marvin W.

1994-01-01

Microgravity can provide a diffusion-dominated environment for double-diffusion and diffusion-reaction experiments otherwise disrupted by buoyant convection or sedimentation. In sliding solvent diffusion cells, a diffusion interface between two liquid columns is achieved by aligning two offset sliding wells. Fluid in contact with the sliding lid of the cavities is subjected to an applied shear stress. The momentum change by the start/stop action of the well creates an additional hydrodynamical force. In microgravity, these viscous and inertial forces are sufficiently large to deform the diffusion interface and induce hydrodynamic transfer between the wells. A series of KC-135 parabolic flight experiments were conducted to characterize these effects and establish baseline data for microgravity diffusion experiments. Flow visualizations show the diffusion interface to be deformed in a sinusoidal fashion following well alignment. After the wells were separated again in a second sliding movement, the total induced liquid transfer was determined and normalized by the well aspect ratio. The normalized transfer decreased linearly with Reynolds number from 3.3 to 4.0% (w/v) for Re = 0.4 (Stokes flow) to a minimum of 1.0% for Re = 23 to 30. Reynolds numbers that provide minimum induced transfers are characterized by an interface that is highly deformed and unsuitable for diffusion measurements. Flat diffusion interfaces acceptable for diffusion measurements are obtained with Reynolds numbers on the order of 7 to 10. Microgravity experiments aboard a sounding rocket flight verified counterdiffusion of different solutes to be diffusion dominated. Ground control experiments showed enhanced mixing by double-diffusive convection. Careful selection of experimental parameters improves initial conditions and minimizes induced transfer rates.

A real-time monitoring platform of myogenesis regulators using double fluorescent labeling

PubMed Central

Sapoznik, Etai; Niu, Guoguang; Zhou, Yu; Prim, Peter M.; Criswell, Tracy L.

2018-01-01

Real-time, quantitative measurement of muscle progenitor cell (myoblast) differentiation is an important tool for skeletal muscle research and identification of drugs that support skeletal muscle regeneration. While most quantitative tools rely on sacrificial approach, we developed a double fluorescent tagging approach, which allows for dynamic monitoring of myoblast differentiation through assessment of fusion index and nuclei count. Fluorescent tagging of both the cell cytoplasm and nucleus enables monitoring of cell fusion and the formation of new myotube fibers, similar to immunostaining results. This labeling approach allowed monitoring the effects of Myf5 overexpression, TNFα, and Wnt agonist on myoblast differentiation. It also enabled testing the effects of surface coating on the fusion levels of scaffold-seeded myoblasts. The double fluorescent labeling of myoblasts is a promising technique to visualize even minor changes in myogenesis of myoblasts in order to support applications such as tissue engineering and drug screening. PMID:29444187

Observing Double Stars

NASA Astrophysics Data System (ADS)

Genet, Russell M.; Fulton, B. J.; Bianco, Federica B.; Martinez, John; Baxter, John; Brewer, Mark; Carro, Joseph; Collins, Sarah; Estrada, Chris; Johnson, Jolyon; Salam, Akash; Wallen, Vera; Warren, Naomi; Smith, Thomas C.; Armstrong, James D.; McGaughey, Steve; Pye, John; Mohanan, Kakkala; Church, Rebecca

2012-05-01

Double stars have been systematically observed since William Herschel initiated his program in 1779. In 1803 he reported that, to his surprise, many of the systems he had been observing for a quarter century were gravitationally bound binary stars. In 1830 the first binary orbital solution was obtained, leading eventually to the determination of stellar masses. Double star observations have been a prolific field, with observations and discoveries - often made by students and amateurs - routinely published in a number of specialized journals such as the Journal of Double Star Observations. All published double star observations from Herschel's to the present have been incorporated in the Washington Double Star Catalog. In addition to reviewing the history of visual double stars, we discuss four observational technologies and illustrate these with our own observational results from both California and Hawaii on telescopes ranging from small SCTs to the 2-meter Faulkes Telescope North on Haleakala. Two of these technologies are visual observations aimed primarily at published "hands-on" student science education, and CCD observations of both bright and very faint doubles. The other two are recent technologies that have launched a double star renaissance. These are lucky imaging and speckle interferometry, both of which can use electron-multiplying CCD cameras to allow short (30 ms or less) exposures that are read out at high speed with very low noise. Analysis of thousands of high speed exposures allows normal seeing limitations to be overcome so very close doubles can be accurately measured.

Influence of the fuel and dosage on the performance of double-compartment microbial fuel cells.

PubMed

Asensio, Y; Fernandez-Marchante, C M; Lobato, J; Cañizares, P; Rodrigo, M A

2016-08-01

This manuscript focuses on the evaluation of the use of different types and dosages of fuels in the performance of double-compartment microbial fuel cell equipped with carbon felt electrodes and cationic membrane. Five types of fuels (ethanol, glycerol, acetate, propionate and fructose) have been tested for the same organic load (5,000 mg L(-1) measured as COD) and for one of them (acetate), the range of dosages between 500 and 20,000 mg L(-1) of COD was also studied. Results demonstrate that production of electricity depends strongly on the fuel used. Carboxylic acids are much more efficient than alcohols or fructose for the same organic load and within the range 500-5,000 mg L(-1) of acetate the production of electricity increases linearly with the amount of acetate fed but over these concentrations a change in the population composition may explain a worse performance. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Human L1 Element Causes DNA Double-Strand Breaks in Breast Cancer

DTIC Science & Technology

2006-08-01

cancer is complex. However, defects in DNA repair genes in the double-strand break repair pathway are cancer predisposing. My lab has characterized...a new potentially important source of double-strand breaks (DSBs) in human cells and are interested in characterizing which DNA repair genes act on...this particular source of DNA damage. Selfish DNA accounts for 45% of the human genome. We have recently demonstrated that one particular selfish

Gene conversion is strongly induced in human cells by double-strand breaks and is modulated by the expression of BCL-x(L)

NASA Technical Reports Server (NTRS)

Wiese, Claudia; Pierce, Andrew J.; Gauny, Stacey S.; Jasin, Maria; Kronenberg, Amy; Chatterjee, A. (Principal Investigator)

2002-01-01

Homology-directed repair (HDR) of DNA double-strand breaks (DSBs) contributes to the maintenance of genomic stability in rodent cells, and it has been assumed that HDR is of similar importance in DSB repair in human cells. However, some outcomes of homologous recombination can be deleterious, suggesting that factors exist to regulate HDR. We demonstrated previously that overexpression of BCL-2 or BCL-x(L) enhanced the frequency of X-ray-induced TK1 mutations, including loss of heterozygosity events presumed to arise by mitotic recombination. The present study was designed to test whether HDR is a prominent DSB repair pathway in human cells and to determine whether ectopic expression of BCL-x(L) affects HDR. Using TK6-neo cells, we find that a single DSB in an integrated HDR reporter stimulates gene conversion 40-50-fold, demonstrating efficient DSB repair by gene conversion in human cells. Significantly, DSB-induced gene conversion events are 3-4-fold more frequent in TK6 cells that stably overexpress the antiapoptotic protein BCL-X(L). Thus, HDR plays an important role in maintaining genomic integrity in human cells, and ectopic expression of BCL-x(L) enhances HDR of DSBs. This is the first study to highlight a function for BCL-x(L) in modulating DSB repair in human cells.

MTOR ACTIVATION TRIGGERS IL-4 PRODUCTION AND NECROTIC DEATH OF DOUBLE-NEGATIVE T CELLS IN PATIENTS WITH SYSTEMIC LUPUS ERYHTHEMATOSUS

PubMed Central

Lai, Zhi-Wei; Borsuk, Rebecca; Shadakshari, Ashwini; Yu, Jianghong; Dawood, Maha; Garcia, Ricardo; Francis, Lisa; Tily, Hajra; Bartos, Adam; Faraone, Stephen V.; Phillips, Paul; Perl, Andras

2013-01-01

The mechanistic target of rapamycin (mTOR) is recognized as a sensor of mitochondrial dysfunction and effector of T-cell lineage development, however, its role in autoimmunity, including systemic lupus erythematosus, remains unclear. Here, we prospectively evaluated mitochondrial dysfunction and mTOR activation in PBL relative to SLE disease activity index (SLEDAI) during 274 visits of 59 patients and 54 matched healthy subjects. Partial least square-discriminant analysis identified 15 of 212 parameters that accounted for 70.2% of the total variance and discriminated lupus and control samples (p<0.0005); increased mitochondrial mass of CD3+/CD4−/CD8− double-negative (DN) T cells (p=1.1×10−22) and FoxP3 depletion in CD4+/CD25+ T cells were top contributors (p=6.7×10−7). Prominent necrosis and mTOR activation were noted in DN T cells during 15 visits characterized by flares (SLEDAI increase ≥4) relative to 61 visits of remission (SLEDAI decrease ≥4). mTOR activation in DN T cells was also noted at pre-flare visits of SLE patients relative to those of stable disease or healthy controls. DN lupus T cells showed increased production of IL-4, which correlated with depletion of CD25+/CD19+B cells. Rapamycin treatment in vivo blocked the IL-4 production and necrosis of DN T cells, increased the expression of FoxP3 in CD25+/CD4+T cells, and expanded CD25+/CD19+ B cells. These results identify mTOR activation to be a trigger of IL-4 production and necrotic death of DN T cells in patients with SLE. PMID:23913957

Distinct CD4+CD8+ Double-Positive T Cells in the Blood and Liver of Patients during Chronic Hepatitis B and C

PubMed Central

Nascimbeni, Michelina; Pol, Stanislas; Saunier, Bertrand

2011-01-01

CD4+ and CD8+ T cells, the main effectors of adaptive cellular immune responses, differentiate from immature, non-functional CD4+CD8+ double-positive T (DPT) cells in the thymus. Increased proportions of circulating DPT lymphocytes have been observed during acute viral infections; in chronic viral diseases, the role and repartition of extra-thymic DPT cells remain largely uncharacterized. We performed a phenotypic analysis of DPT cells in blood and liver from patients chronically infected by hepatitis C (HCV) or B (HBV) viruses. The highest percentages of DPT cells, predominantly CD4highCD8low, were observed in patients infected by HCV, while HBV-infected patients mostly displayed CD4lowCD8high and CD4highCD8high DPT cells. All proportions of DPT cells were higher in liver than in blood with, for each subpopulation referred to above, a correlation between their frequencies in these two compartments. In HCV patients, intra-hepatic DPT cells displayed more heterogeneous activation, differentiation and memory phenotypes than in the blood; most of them expressed CD1a, a marker of T cell development in the thymus. Ex vivo, the inoculation of liver slices with HCV produced in cell culture was accompanied by a disappearance of CD8high cells, suggesting a direct effect of the virus on the phenotype of DPT cells in the liver. Our results suggest that, in half of the patients, chronic HCV infection promotes the production of DPT cells, perhaps by their re-induction in the thymus and selection in the liver. PMID:21647449

Recent advances in the cell biology of aging.

PubMed

Hayflick, L

1980-01-01

Cultured normal human and animal cells are predestined to undergo irreversible functional decrements that mimic age changes in the whole organism. When normal human embryonic fibroblasts are cultured in vitro, 50 +/- 10 population doublings occur. This maximum potential is diminished in cells derived from older donors and appears to be inversely proportional to their age. The 50 population doubling limit can account for all cells produced during a lifetime. The limitation on doubling potential of cultured normal cells is also expressed in vivo when serial transplants are made. There may be a direct correlation between the mean maximum life spans of several species and the population doubling potential of their cultured cells. A plethora of functional decrements occurs in cultured normal cells as they approach their maximum division capability. Many of these decrements are similar to those occurring in intact animals as they age. We have concluded that these functional decrements expressed in vitro, rather than cessation of cell division, are the essential contributors to age changes in intact animals. Thus, the study of events leading to functional losses in cultured normal cells may provide useful insights into the biology of aging.

The morphology, proliferation rate, and population doubling time factor of adipose-derived mesenchymal stem cells cultured on to non-aqueous SiO2, TiO2, and hybrid sol-gel-derived oxide coatings.

PubMed

Marycz, Krzysztof; Krzak-Roś, Justyna; Donesz-Sikorska, Anna; Śmieszek, Agnieszka

2014-11-01

In recent years, much attention has been paid to the development of tissue engineering and regenerative medicine, especially when stem cells of various sources are concerned. In addition to the interest in mesenchymal stem cells isolated from bone marrow, recently more consideration has been given to stem cells isolated from adipose tissue (AdMSCs), due to their less invasive method of collection as well as their ease of isolation and culture. However, the development of regenerative medicine requires both the application of biocompatible material and the stem cells to accelerate the regeneration. In this study, we investigated the morphology, proliferation rate index (PRi), and population doubling time factor of adipose-derived mesenchymal stem cells cultured on non-aqueous sol-gel-derived SiO2, TiO2, and SiO2/TiO2 oxide coatings. The results indicated an increase in PRi of AdMSCs when cultured on to titanium dioxide, suggesting its high attractiveness for AdMSCs. In addition, the proper morphology and the shortest doubling time of AdMSCs were observed when cultured on titanium dioxide coating. © 2014 Wiley Periodicals, Inc.

An alternative mechanism for radioprotection by dimethyl sulfoxide; possible facilitation of DNA double-strand break repair.

PubMed

Kashino, Genro; Liu, Yong; Suzuki, Minoru; Masunaga, Shin-ichiro; Kinashi, Yuko; Ono, Koji; Tano, Keizo; Watanabe, Masami

2010-01-01

The radioprotective effects of dimethyl sulfoxide (DMSO) have been known for many years, and the suppression of hydroxyl (OH) radicals induced by ionizing radiation has been thought to be the main cause of this effect. However, the DMSO concentration used was very high, and might be toxic, in earlier studies. In the present study, we administered a lower, non-toxic concentration (0.5%, i.e., 64 mM) of DMSO before irradiation and examined its radioprotective effects. Colony formation assay and micronucleus assay showed significant radioprotective effects in CHO, but not in xrs5, which is defective in the repair function of DNA double-strand breaks. The levels of phosphorylated H2AX and the formation of 53BP1 foci 15 minutes after irradiation, which might reflect initial DNA double-strand breaks, in DMSO-treated CHO cells were similar to those in non-treated cells, suggesting that the radioprotective effects were not attributable to the suppression of general indirect action in the lower concentration of DMSO. On the other hand, 2 hours after irradiation, the average number of 53BP1 foci, which might reflect residual DNA double-strand breaks, was significantly decreased in DMSO-treated CHO cells compared to non-treated cells. The results indicated that low concentration of DMSO exerts radioprotective effects through the facilitation of DNA double-strand break repair rather than through the suppression of indirect action.

Active site-directed double mutants of dihydrofolate reductase.

PubMed

Ercikan-Abali, E A; Mineishi, S; Tong, Y; Nakahara, S; Waltham, M C; Banerjee, D; Chen, W; Sadelain, M; Bertino, J R

1996-09-15

Variants of dihydrofolate reductase (DHFR), which confer resistance to antifolates, are used as dominant selectable markers in vitro and in vivo and may be useful in the context of gene therapy. To identify improved mutant human DHFRs with increased catalytic efficiency and decreased binding to methotrexate, we constructed by site-directed mutagenesis four variants with substitutions at both Leu22 and Phe31 (i.e., Phe22-Ser31, Tyr22-Ser31, Phe22-Gly31, and Tyr22-Gly31). Antifolate resistance has been observed previously when individual changes are made at these active-site residues. Substrate and antifolate binding properties of these "double" mutants revealed that each have greatly diminished affinity for antifolates (> 10,000-fold) yet only slightly reduced substrate affinity. Comparison of in vitro measured properties with those of single-residue variants indicates that double mutants are indeed significantly superior. This was verified for one of the double mutants that provided high-level methotrexate resistance following retrovirus-mediated gene transfer in NIH3T3 cells.

6-mercaptopurine and daunorubicin double drug liposomes-preparation, drug-drug interaction and characterization.

PubMed

Agrawal, Vineet; Paul, Manash K; Mukhopadhyay, Anup K

2005-01-01

This article addresses and investigates the dual incorporation of daunorubicin (DR) and 6-mercaptopurine (6-MP) in liposomes for better chemotherapy. These drugs are potential candidates for interaction due to the quinone (H acceptor) and hydroxyl (H donor) groups on DR and 6-MP, respectively. Interactions between the two drugs in solution were monitored by UV/Vis and fluorescence spectroscopy. Interaction between the two drugs inside the liposomes was evaluated by HPLC (for 6-MP) and by fluorescence spectroscopy (for daunorubicin) after phospholipase-mediated liposome lysis. Our results provide evidence for the lack of interaction between the two drugs in solution and in liposomes. The entrapment efficiencies of 6-MP in the neutral Phosphatidyl choline (PC):Cholesterol (Chol):: 2:1 and anionic PC:Chol:Cardiolipin (CL) :: 4:5:1 single and double drug liposomes were found to be 0.4% and 1.5% (on average), respectively. The entrapment efficiencies of DR in the neutral and anionic double drug liposomes were found to be 55% and 31%, respectively. The corresponding entrapment of daunorubicin in the single drug liposomes was found to be 62% on average. Our thin layer chromatography (TLC) and transmission electron microscopy (TEM) results suggest stability of lipid and liposomes, thus pointing plausible existence of double drug liposomes. Cytotoxicity experiments were performed by using both single drug and double drug liposomes. By comparing the results of phase contrast and fluorescence microscopy, it was observed that the double drug liposomes were internalized in the jurkat and Hut78 (highly resistant cell line) leukemia cells as viewed by the fluorescence of daunorubicin. The cytotoxicity was dose dependent and had shown a synergistic effect when double drug liposome was used.

Intra-species bacterial quorum sensing studied at single cell level in a double droplet trapping system.

PubMed

Bai, Yunpeng; Patil, Santoshkumar N; Bowden, Steven D; Poulter, Simon; Pan, Jie; Salmond, George P C; Welch, Martin; Huck, Wilhelm T S; Abell, Chris

2013-05-21

In this paper, we investigated the intra-species bacterial quorum sensing at the single cell level using a double droplet trapping system. Escherichia coli transformed to express the quorum sensing receptor protein, LasR, were encapsulated in microdroplets that were positioned adjacent to microdroplets containing the autoinducer, N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL). Functional activation of the LasR protein by diffusion of the OdDHL across the droplet interface was measured by monitoring the expression of green fluorescent protein (GFP) from a LasR-dependent promoter. A threshold concentration of OdDHL was found to induce production of quorum-sensing associated GFP by E. coli. Additionally, we demonstrated that LasR-dependent activation of GFP expression was also initiated when the adjacent droplets contained single E. coli transformed with the OdDHL synthase gene, LasI, representing a simple quorum sensing circuit between two droplets.

Nitrogen removal and electricity production at a double-chamber microbial fuel cell with cathode nitrite denitrification.

PubMed

Yu, Yangyang; Zhao, Jianqiang; Wang, Sha; Zhao, Huimin; Ding, Xiaoqian; Gao, Kun

2017-12-01

Double-chamber microbial fuel cell was applied to investigate the performance of the electricity production and nitrite denitrification through feeding nitrite into the cathode. Factors influencing denitrification performance and power production, such as external resistance, influent nitrite concentration and Nitrite Oxygen Bacteria inhibitors, were studied. The results show that when the concentration of nitrite nitrogen and external resistance were 100 mg L -1 and 10 Ω, respectively, the nitrite denitrification reached the best state. The NaN 3 can inhibit nitrite oxidation effectively; meanwhile, the nitrite denitrification with N 2 O as the final products was largely improved. The [Formula: see text] was reduced to [Formula: see text], causing the cathode denitrification coulombic efficiency to exceed 100%. In chemoautotrophic bio-nitrification, microorganisms may utilize H 2 O to oxidize nitrite under anaerobic conditions. Proteobacteria might play a major role in the process of denitrification in MFC.

Vapor Pressure Measurements of LiBH4, NaBH 4 and Ca(BH4)2 using Knudsen Torsion Effusion Gravimetric Method

NASA Astrophysics Data System (ADS)

Danyan, Mohammad Masoumi

Hydrogen storage is one of the critical technologies needed on the path towards commercialization for mobile applications. In the past few years, a range of new light weight hydrogen containing material has been discovered with good storage properties. Among them, lithium borohydride (LiBH 4) sodium borohydride (NaBH4) and calcium borohydride (Ca(BH 4)2) have shown promising results to be used as solid state hydrogen storage material. In this work, we have determined equilibrium vapor pressures of LiBH 4 NaBH4 and Ca(BH4)2 obtained by Torsion effusion thermogravimetric method. Results for all the three hydrides exhibited that a small fraction of the materials showed congruency, and sublimed as gaseous compound, but the majority of the material showed incongruent vaporization. Two Knudsen cells of 0.3 and 0.6mm orifice size was employed to measure the total vapor pressures. A Whitman-Motzfeldt method is used to extrapolate the measured vapor pressures to zero orifice size to calculate the equilibrium vapor pressures. In the case of LiBH4 we found that 2% of the material evaporated congruently (LiBH4(s) → LiBH4(g)) according to the equation: logPLiBH4/P 0 =-3263.5 +/-309/T + (1.079 +/-0.69) and rest as incongruent vaporization to LiH, B, and hydrogen gas according to the equation logPeq/P0 =(-3263.5 +/-309)/T+ (2.458 +/-0.69) with DeltaH evap.= 62.47+/-5.9 kJ/mol of H2, DeltaSevap. = 47.05+/-13 J/mol of H2.K. The NaBH4 also had somewhat similar behavior, with 9% congruent evaporation and equilibrium vapor pressure equation of logPLiBH4=-7700+/-335/ T+ (6.7+/-1.5) and 91% incongruent decomposition to Na and Boron metal, and hydrogen gas. The enthalpy of vaporization; DeltaHevap. = 147.2+/-6.4kJ/molH2 and DeltaSevap.= 142 +/-28 kJ/molH2.K (550-650K). The Ca(BH4) 2 exhibited similar vaporization behavior with congruency of 3.2%. The decomposition products are CaH2 and Boron metal with evolution of hydrogen gas varying with the pressure equation as logPeq /P0 =(-1562

Double-perovskites A 2FeMoO 6- δ (A = Ca, Sr, Ba) as anodes for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Zhang, Leilei; Zhou, Qingjun; He, Qiang; He, Tianmin

Double-perovskites A 2FeMoO 6- δ (A = Ca, Sr, Ba) have been investigated as potential anode materials for solid oxide fuel cells (SOFCs). At room temperature, A 2FeMoO 6- δ compounds crystallize in monoclinic, tetragonal, and cubic structures for A = Ca, Sr, and Ba, respectively. A weak peak observed at around 880 cm -1 in the Raman spectra can be attributed to traces of AMoO 4. XPS has confirmed the coexistence of Fe 2+-Mo 6+ and Fe 3+-Mo 5+ electronic configurations. Moreover, a systematic shift from Fe 2+/3+-Mo 6+/5+ to Fe 2+-Mo 6+ configuration is seen with increasing A-site cation size. A 2FeMoO 6- δ samples display distinct electrical properties in H 2, which can be attributed to different degrees of degeneracy of the Fe 2+-Mo 6+ and Fe 3+-Mo 5+ configurations. Ca 2FeMoO 6- δ is unstable in a nitrogen atmosphere, while Sr 2FeMoO 6- δ and Ba 2FeMoO 6- δ are stable up to 1200 °C. The thermal expansion coefficients of Sr 2FeMoO 6- δ and Ba 2FeMoO 6- δ are very close to that of La 0.9Sr 0.1Ga 0.8Mg 0.2O 3- δ (LSGM). The performances of cells with 300 μm thick LSGM electrolyte, double-perovskite SmBaCo 2O 5+ x cathodes, and A 2FeMoO 6- δ anodes follow the sequence Ca 2FeMoO 6- δ < Ba 2FeMoO 6- δ < Sr 2FeMoO 6- δ. The maximum power densities of a cell with an Sr 2FeMoO 6- δ anode reach 831 mW cm -2 in dry H 2 and 735 mW cm -2 in commercial city gas at 850 °C, respectively.

Effect of primary and secondary parameters on analytical estimation of effective thermal conductivity of two phase materials using unit cell approach

NASA Astrophysics Data System (ADS)

S, Chidambara Raja; P, Karthikeyan; Kumaraswamidhas, L. A.; M, Ramu

2018-05-01

Most of the thermal design systems involve two phase materials and analysis of such systems requires detailed understanding of the thermal characteristics of the two phase material. This article aimed to develop geometry dependent unit cell approach model by considering the effects of all primary parameters (conductivity ratio and concentration) and secondary parameters (geometry, contact resistance, natural convection, Knudsen and radiation) for the estimation of effective thermal conductivity of two-phase materials. The analytical equations have been formulated based on isotherm approach for 2-D and 3-D spatially periodic medium. The developed models are validated with standard models and suited for all kind of operating conditions. The results have shown substantial improvement compared to the existing models and are in good agreement with the experimental data.

Double checking: a second look

PubMed Central

Chreim, Samia; Forster, Alan

2015-01-01

Abstract Rationale, aims and objectives Double checking is a standard practice in many areas of health care, notwithstanding the lack of evidence supporting its efficacy. We ask in this study: ‘How do front line practitioners conceptualize double checking? What are the weaknesses of double checking? What alternate views of double checking could render it a more robust process?’ Method This is part of a larger qualitative study based on 85 semi‐structured interviews of health care practitioners in general internal medicine and obstetrics and neonatology; thematic analysis of the transcribed interviews was undertaken. Inductive and deductive themes are reported. Results Weaknesses in the double checking process include inconsistent conceptualization of double checking, double (or more) checking as a costly and time‐consuming procedure, double checking trusted as an accepted and stand‐alone process, and double checking as preventing reporting of near misses. Alternate views of double checking that would render it a more robust process include recognizing that double checking requires training and a dedicated environment, Introducing automated double checking, and expanding double checking beyond error detection. These results are linked with the concepts of collective efficiency thoroughness trade off (ETTO), an in‐family approach, and resilience. Conclusion(s) Double checking deserves more questioning, as there are limitations to the process. Practitioners could view double checking through alternate lenses, and thus help strengthen this ubiquitous practice that is rarely challenged. PMID:26568537

Forkhead box-P3+ regulatory T cells and toll-like receptor 2 co-expression in oral squamous cell carcinoma.

PubMed

Hussaini, H M; Parachuru, V P B; Seymour, G J; Rich, A M

2017-04-01

The function of forkhead box-P3 (FoxP3) regulatory T cells (Treg) and toll-like receptor (TLR)2 protein in the oral cancer microenvironment is not fully understood, but evidence from other malignancies suggests it is likely they are involved with tumour development and progression. The aim of this study was to investigate the distribution of FoxP3 + cells, TLR2 + cells and double-labelled FoxP3 + TLR2 + immune cells in oral squamous cell carcinoma (OSCC), using immunohistochemistry (IHC) and immunofluorescence (IF). 25 archival cases of OSCC were immunostained with anti-FoxP3 and anti-TLR2 antibodies. Inflamed hyperplastic oral mucosal tissues were used as controls. The proportion of single-labelled, double-labelled and negative cells was determined. A higher frequency of double-labelled FoxP3 + TLR2 + Tregs was observed within the immune cells of OSCC compared to inflamed controls using IHC (p<0.05). Cell-to-cell contact between single-stained TLR2 + cells and FoxP3 + cells was noted. Double IF studies validated demonstration of co-expression of FoxP3 + /TLR2 + immune cells in OSCC. The presence of FoxP3 + TLR2 + cells within the OSCC microenvironment may represent a dendritic cell-dependent pathway capable of inhibiting Treg suppressive activity, potentially enhancing the anti-tumour response. Modulation of TLR2-Treg interactions should be further explored to determine if they have a role in the therapeutic management of OSCC. Copyright © 2017 Elsevier GmbH. All rights reserved.

Laccase electrodes based on the combination of single-walled carbon nanotubes and redox layered double hydroxides: Towards the development of biocathode for biofuel cells

NASA Astrophysics Data System (ADS)

Ding, Shou-Nian; Holzinger, Michael; Mousty, Christine; Cosnier, Serge

Single-walled carbon nanotubes (SWCNT) were combined with layered double hydroxides (LDH) intercalated with 2,2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonate) diammonium salt [ZnCr-ABTS] to entrap and electrically connect laccase enzyme. The resulting laccase electrodes exhibited an electro-enzymatic activity for O 2 reduction. To improve this electrocatalytic activity, varying SWCNT quantities and loading methods were tested to optimize the configuration of the laccase electrodes. Furthermore, the resulting bioelectrode was successfully used as a biocathode for the elaboration of a membrane-less glucose/air biofuel cell. In 0.1 M phosphate buffer (PBS) of pH 6.0, containing glucose (5 mM) under ambient conditions, the assembled biofuel cell yielded a maximum power density of 18 μW cm -2 at a cell voltage of 0.3 V whereas this power decreased to 8.3 μW cm -2 for a biofuel cell based on the identical biocathode setup without SWCNT.

Septin9 is involved in T-cell development and CD8+ T-cell homeostasis.

PubMed

Lassen, Louise Berkhoudt; Füchtbauer, Annette; Schmitz, Alexander; Sørensen, Annette Balle; Pedersen, Finn Skou; Füchtbauer, Ernst-Martin

2013-06-01

SEPTIN9 (SEPT9) is a filament-forming protein involved in numerous cellular processes. We have used a conditional knock out allele of Sept9 to specifically delete Sept9 in T-cells. As shown by fluorescence-activated cell sorting, loss of Sept9 at an early thymocyte stage in the thymus results in increased numbers of double-negative cells indicating that SEPT9 is involved in the transition from the double-negative stage during T-cell development. Accordingly, the relative numbers of mature T-cells in the periphery are decreased in mice with a T-cell-specific deletion of Sept9. Proliferation of Sept9-deleted CD8(+) T-cells from the spleen is decreased upon stimulation in culture. The altered T-cell homeostasis caused by the loss of Sept9 results in an increase of CD8(+) central memory T-cells.

I-SceI-mediated double-strand break does not increase the frequency of homologous recombination at the Dct locus in mouse embryonic stem cells.

PubMed

Fenina, Myriam; Simon-Chazottes, Dominique; Vandormael-Pournin, Sandrine; Soueid, Jihane; Langa, Francina; Cohen-Tannoudji, Michel; Bernard, Bruno A; Panthier, Jean-Jacques

2012-01-01

Targeted induction of double-strand breaks (DSBs) at natural endogenous loci was shown to increase the rate of gene replacement by homologous recombination in mouse embryonic stem cells. The gene encoding dopachrome tautomerase (Dct) is specifically expressed in melanocytes and their precursors. To construct a genetic tool allowing the replacement of Dct gene by any gene of interest, we generated an embryonic stem cell line carrying the recognition site for the yeast I-SceI meganuclease embedded in the Dct genomic segment. The embryonic stem cell line was electroporated with an I-SceI expression plasmid, and a template for the DSB-repair process that carried sequence homologies to the Dct target. The I-SceI meganuclease was indeed able to introduce a DSB at the Dct locus in live embryonic stem cells. However, the level of gene targeting was not improved by the DSB induction, indicating a limited capacity of I-SceI to mediate homologous recombination at the Dct locus. These data suggest that homologous recombination by meganuclease-induced DSB may be locus dependent in mammalian cells.

The double-stranded RNA binding protein RDE-4 can act cell autonomously during feeding RNAi in C. elegans

PubMed Central

Raman, Pravrutha; Zaghab, Soriayah M.; Traver, Edward C.

2017-01-01

Abstract Long double-stranded RNA (dsRNA) can silence genes of matching sequence upon ingestion in many invertebrates and is therefore being developed as a pesticide. Such feeding RNA interference (RNAi) is best understood in the worm Caenorhabditis elegans, where the dsRNA-binding protein RDE-4 initiates silencing by recruiting an endonuclease to process long dsRNA into short dsRNA. These short dsRNAs are thought to move between cells because muscle-specific rescue of rde-4 using repetitive transgenes enables silencing in other tissues. Here, we extend this observation using additional promoters, report an inhibitory effect of repetitive transgenes, and discover conditions for cell-autonomous silencing in animals with tissue-specific rescue of rde-4. While expression of rde-4(+) in intestine, hypodermis, or neurons using a repetitive transgene can enable silencing also in unrescued tissues, silencing can be inhibited wihin tissues that express a repetitive transgene. Single-copy transgenes that express rde-4(+) in body-wall muscles or hypodermis, however, enable silencing selectively in the rescued tissue but not in other tissues. These results suggest that silencing by the movement of short dsRNA between cells is not an obligatory feature of feeding RNAi in C. elegans. We speculate that similar control of dsRNA movement could modulate tissue-specific silencing by feeding RNAi in other invertebrates. PMID:28541563

DETECTION OF EQUATORWARD MERIDIONAL FLOW AND EVIDENCE OF DOUBLE-CELL MERIDIONAL CIRCULATION INSIDE THE SUN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao Junwei; Bogart, R. S.; Kosovichev, A. G.

2013-09-10

Meridional flow in the solar interior plays an important role in redistributing angular momentum and transporting magnetic flux inside the Sun. Although it has long been recognized that the meridional flow is predominantly poleward at the Sun's surface and in its shallow interior, the location of the equatorward return flow and the meridional flow profile in the deeper interior remain unclear. Using the first 2 yr of continuous helioseismology observations from the Solar Dynamics Observatory/Helioseismic Magnetic Imager, we analyze travel times of acoustic waves that propagate through different depths of the solar interior carrying information about the solar interior dynamics.more » After removing a systematic center-to-limb effect in the helioseismic measurements and performing inversions for flow speed, we find that the poleward meridional flow of a speed of 15 m s{sup -1} extends in depth from the photosphere to about 0.91 R{sub Sun }. An equatorward flow of a speed of 10 m s{sup -1} is found between 0.82 and 0.91 R{sub Sun} in the middle of the convection zone. Our analysis also shows evidence of that the meridional flow turns poleward again below 0.82 R{sub Sun }, indicating an existence of a second meridional circulation cell below the shallower one. This double-cell meridional circulation profile with an equatorward flow shallower than previously thought suggests a rethinking of how magnetic field is generated and redistributed inside the Sun.« less

Nontoxic concentration of DNA-PK inhibitor NU7441 radio-sensitizes lung tumor cells with little effect on double strand break repair.

PubMed

Sunada, Shigeaki; Kanai, Hideki; Lee, Younghyun; Yasuda, Takeshi; Hirakawa, Hirokazu; Liu, Cuihua; Fujimori, Akira; Uesaka, Mitsuru; Okayasu, Ryuichi

2016-09-01

High-linear energy transfer (LET) heavy ions have been increasingly employed as a useful alternative to conventional photon radiotherapy. As recent studies suggested that high LET radiation mainly affects the nonhomologous end-joining (NHEJ) pathway of DNA double strand break (DSB) repair, we further investigated this concept by evaluating the combined effect of an NHEJ inhibitor (NU7441) at a non-toxic concentration and carbon ions. NU7441-treated non-small cell lung cancer (NSCLC) A549 and H1299 cells were irradiated with X-rays and carbon ions (290 MeV/n, 50 keV/μm). Cell survival was measured by clonogenic assay. DNA DSB repair, cell cycle distribution, DNA fragmentation and cellular senescence induction were studied using a flow cytometer. Senescence-associated protein p21 was detected by western blotting. In the present study, 0.3 μM of NU7441, nontoxic to both normal and tumor cells, caused a significant radio-sensitization in tumor cells exposed to X-rays and carbon ions. This concentration did not seem to cause inhibition of DNA DSB repair but induced a significant G2/M arrest, which was particularly emphasized in p53-null H1299 cells treated with NU7441 and carbon ions. In addition, the combined treatment induced more DNA fragmentation and a higher degree of senescence in H1299 cells than in A549 cells, indicating that DNA-PK inhibitor contributes to various modes of cell death in a p53-dependent manner. In summary, NSCLC cells irradiated with carbon ions were radio-sensitized by a low concentration of DNA-PK inhibitor NU7441 through a strong G2/M cell cycle arrest. Our findings may contribute to further effective radiotherapy using heavy ions. © 2016 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

The over-expression of the β2 catalytic subunit of the proteasome decreases homologous recombination and impairs DNA double-strand break repair in human cells.

PubMed

Collavoli, Anita; Comelli, Laura; Cervelli, Tiziana; Galli, Alvaro

2011-01-01

By a human cDNA library screening, we have previously identified two sequences coding two different catalytic subunits of the proteasome which increase homologous recombination (HR) when overexpressed in the yeast Saccharomyces cerevisiae. Here, we investigated the effect of proteasome on spontaneous HR and DNA repair in human cells. To determine if the proteasome has a role in the occurrence of spontaneous HR in human cells, we overexpressed the β2 subunit of the proteasome in HeLa cells and determined the effect on intrachromosomal HR. Results showed that the overexpression of β2 subunit decreased HR in human cells without altering the cell proteasome activity and the Rad51p level. Moreover, exposure to MG132 that inhibits the proteasome activity reduced HR in human cells. We also found that the expression of the β2 subunit increases the sensitivity to the camptothecin that induces DNA double-strand break (DSB). This suggests that the β2 subunit has an active role in HR and DSB repair but does not alter the intracellular level of the Rad51p.

The Over-expression of the β2 Catalytic Subunit of the Proteasome Decreases Homologous Recombination and Impairs DNA Double-Strand Break Repair in Human Cells

PubMed Central

Collavoli, Anita; Comelli, Laura; Cervelli, Tiziana; Galli, Alvaro

2011-01-01

By a human cDNA library screening, we have previously identified two sequences coding two different catalytic subunits of the proteasome which increase homologous recombination (HR) when overexpressed in the yeast Saccharomyces cerevisiae. Here, we investigated the effect of proteasome on spontaneous HR and DNA repair in human cells. To determine if the proteasome has a role in the occurrence of spontaneous HR in human cells, we overexpressed the β2 subunit of the proteasome in HeLa cells and determined the effect on intrachromosomal HR. Results showed that the overexpression of β2 subunit decreased HR in human cells without altering the cell proteasome activity and the Rad51p level. Moreover, exposure to MG132 that inhibits the proteasome activity reduced HR in human cells. We also found that the expression of the β2 subunit increases the sensitivity to the camptothecin that induces DNA double-strand break (DSB). This suggests that the β2 subunit has an active role in HR and DSB repair but does not alter the intracellular level of the Rad51p. PMID:21660142

Defective double-strand DNA break repair and chromosomal translocations by MYC overexpression.

PubMed

Karlsson, Asa; Deb-Basu, Debabrita; Cherry, Athena; Turner, Stephanie; Ford, James; Felsher, Dean W

2003-08-19

DNA repair mechanisms are essential for the maintenance of genomic integrity. Disruption of gene products responsible for DNA repair can result in chromosomal damage. Improperly repaired chromosomal damage can result in the loss of chromosomes or the generation of chromosomal deletions or translocations, which can lead to tumorigenesis. The MYC protooncogene is a transcription factor whose overexpression is frequently associated with human neoplasia. MYC has not been previously implicated in a role in DNA repair. Here we report that the overexpression of MYC disrupts the repair of double-strand DNA breaks, resulting in a several-magnitude increase in chromosomal breaks and translocations. We found that MYC inhibited the repair of gamma irradiation DNA breaks in normal human cells and blocked the repair of a single double-strand break engineered to occur in an immortal cell line. By spectral karyotypic analysis, we found that MYC even within one cell division cycle resulted in a several-magnitude increase in the frequency of chromosomal breaks and translocations in normal human cells. Hence, MYC overexpression may be a previously undescribed example of a dominant mutator that may fuel tumorigenesis by inducing chromosomal damage.

Microscale Thermal-Transpiration Gas Pump

NASA Technical Reports Server (NTRS)

Vargo, Stephen; Muntz, Phillip; Shiflett, Geoff

2003-01-01

A recent addition to the growing class of microelectromechanical systems (MEMS) is a single stage of a Knudsen compressor. This device was fabricated and tested to demonstrate the feasibility of Knudsen compressors as miniature vacuum pumps for future portable scientific instruments. The attributes of Knudsen compressors that make them attractive as miniature vacuum pumps are that they contain no moving parts and operate without need for lubricants or working fluids.

The Synergy of Double Cross-linking Agents on the Properties of Styrene Butadiene Rubber Foams

PubMed Central

Shao, Liang; Ji, Zhan-You; Ma, Jian-Zhong; Xue, Chao-Hua; Ma, Zhong-Lei; Zhang, Jing

2016-01-01

Sulfur (S) cross-linking styrene butadiene rubber (SBR) foams show high shrinkage due to the cure reversion, leading to reduced yield and increased processing cost. In this paper, double cross-linking system by S and dicumyl peroxide (DCP) was used to decrease the shrinkage of SBR foams. Most importantly, the synergy of double cross-linking agents was reported for the first time to our knowledge. The cell size and its distribution of SBR foams were investigated by FESEM images, which show the effect of DCP content on the cell structure of the SBR foams. The relationships between shrinkage and crystalline of SBR foams were analyzed by the synergy of double cross-linking agents, which were demonstrated by FTIR, Raman spectra, XRD, DSC and TGA. When the DCP content was 0.6 phr, the SBR foams exhibit excellent physical and mechanical properties such as low density (0.223 g/cm3), reduced shrinkage (2.25%) and compression set (10.96%), as well as elevated elongation at break (1.78 × 103%) and tear strength (54.63 N/mm). The results show that these properties are related to the double cross-linking system of SBR foams. Moreover, the double cross-linking SBR foams present high electromagnetic interference (EMI) shielding properties compared with the S cross-linking SBR foams. PMID:27841307

The Synergy of Double Cross-linking Agents on the Properties of Styrene Butadiene Rubber Foams

NASA Astrophysics Data System (ADS)

Shao, Liang; Ji, Zhan-You; Ma, Jian-Zhong; Xue, Chao-Hua; Ma, Zhong-Lei; Zhang, Jing

2016-11-01

Sulfur (S) cross-linking styrene butadiene rubber (SBR) foams show high shrinkage due to the cure reversion, leading to reduced yield and increased processing cost. In this paper, double cross-linking system by S and dicumyl peroxide (DCP) was used to decrease the shrinkage of SBR foams. Most importantly, the synergy of double cross-linking agents was reported for the first time to our knowledge. The cell size and its distribution of SBR foams were investigated by FESEM images, which show the effect of DCP content on the cell structure of the SBR foams. The relationships between shrinkage and crystalline of SBR foams were analyzed by the synergy of double cross-linking agents, which were demonstrated by FTIR, Raman spectra, XRD, DSC and TGA. When the DCP content was 0.6 phr, the SBR foams exhibit excellent physical and mechanical properties such as low density (0.223 g/cm3), reduced shrinkage (2.25%) and compression set (10.96%), as well as elevated elongation at break (1.78 × 103%) and tear strength (54.63 N/mm). The results show that these properties are related to the double cross-linking system of SBR foams. Moreover, the double cross-linking SBR foams present high electromagnetic interference (EMI) shielding properties compared with the S cross-linking SBR foams.

Cellular trafficking of low molecular weight heparin incorporated in layered double hydroxide nanoparticles in rat vascular smooth muscle cells.

PubMed

Gu, Zi; Rolfe, Barbara E; Thomas, Anita C; Campbell, Julie H; Lu, G Q Max; Xu, Zhi P

2011-10-01

This paper reports a clear elucidation of the pathway for the cellular delivery of layered double hydroxide (LDH) nanoparticles intercalated with anti-restenotic low molecular weight heparin (LMWH). Cellular uptake of LMWH-LDH conjugates into cultured rat vascular smooth muscle cells (SMCs) measured via flow cytometry was more than ten times greater than that of LMWH alone. Confocal and transmission electron microscopy showed LMWH-LDH conjugates taken up by endosomes, then released into the cytoplasm. We propose that LMWH-LDH is taken up via a unique 'modified endocytic' pathway, whereby the conjugate is internalized by SMCs in early endosomes, sorted in late endosomes, and quickly released from late endosomes/lysosomes, avoiding degradation. Treatment of cells with LMWH-LDH conjugates suppressed the activation of ERK1/2 in response to foetal calf serum (FCS) for up to 24h, unlike unconjugated LMWH which had no significant effect at 24h. Improved understanding of the intracellular pathway of LMWH-LDH nanohybrids in SMC will allow for refinement of design for LDH nanomedicine applications. Copyright © 2011 Elsevier Ltd. All rights reserved.

Double displacement: An improved bioorthogonal reaction strategy for templated nucleic acid detection.

PubMed

Kleinbaum, Daniel J; Miller, Gregory P; Kool, Eric T

2010-06-16

Quenched autoligation probes have been employed previously in a target-templated nonenzymatic ligation strategy for detecting nucleic acids in cells by fluorescence. A common source of background signal in such probes is the undesired reaction with water and other cellular nucleophiles. Here, we describe a new class of self-ligating probes, double displacement (DD) probes, that rely on two displacement reactions to fully unquench a nearby fluorophore. Three potential double displacement architectures, all possessing two fluorescence quencher/leaving groups (dabsylate groups), were synthesized and evaluated for templated reaction with nucleophile (phosphorothioate) probes both in vitro and in intact bacterial cells. All three DD probe designs provided substantially better initial quenching than a single-Dabsyl control. In isothermal templated reactions in vitro, double displacement probes yielded considerably lower background signal than previous single displacement probes; investigation into the mechanism revealed that one dabsylate acts as a sacrificial leaving group, reacting nonspecifically with water, but yielding little signal because another quencher group remains. Templated reaction with the specific nucleophile probe is required to activate a signal. The double displacement probes provided a ca. 80-fold turn-on signal and yielded a 2-4-fold improvement in signal/background over single Dabsyl probes. The best-performing probe architecture was demonstrated in a two-color, FRET-based two-allele discrimination system in vitro and was shown to be capable of discriminating between two closely related species of bacteria differing by a single nucleotide at an rRNA target site.

Chromosome thripsis by DNA double strand break clusters causes enhanced cell lethality, chromosomal translocations and 53BP1-recruitment

PubMed Central

Schipler, Agnes; Mladenova, Veronika; Soni, Aashish; Nikolov, Vladimir; Saha, Janapriya; Mladenov, Emil; Iliakis, George

2016-01-01

Chromosome translocations are hallmark of cancer and of radiation-induced cell killing, reflecting joining of incongruent DNA-ends that alter the genome. Translocation-formation requires DNA end-joining mechanisms and incompletely characterized, permissive chromatin conditions. We show that chromatin destabilization by clusters of DNA double-strand-breaks (DSBs) generated by the I-SceI meganuclease at multiple, appropriately engineered genomic sites, compromises c-NHEJ and markedly increases cell killing and translocation-formation compared to single-DSBs. Translocation-formation from DSB-clusters utilizes Parp1 activity, implicating alt-EJ in their formation. Immunofluorescence experiments show that single-DSBs and DSB-clusters uniformly provoke the formation of single γ-H2AX foci, suggesting similar activation of early DNA damage response (DDR). Live-cell imaging also shows similar single-focus recruitment of the early-response protein MDC1, to single-DSBs and DSB-clusters. Notably, the late DDR protein, 53BP1 shows in live-cell imaging strikingly stronger recruitment to DSB-clusters as compared to single-DSBs. This is the first report that chromatin thripsis, in the form of engineered DSB-clusters, compromises first-line DSB-repair pathways, allowing alt-EJ to function as rescuing-backup. DSB-cluster-formation is indirectly linked to the increased biological effectiveness of high ionization-density radiations, such as the alpha-particles emitted by radon gas or the heavy-ions utilized in cancer therapy. Our observations provide the first direct mechanistic explanation for this long-known effect. PMID:27257076

Low joining efficiency and non-conservative repair of two distant double-strand breaks in mouse embryonic stem cells.

PubMed

Boubakour-Azzouz, Imenne; Ricchetti, Miria

2008-02-01

Efficient and faithful repair of DNA double-strand breaks (DSBs) is critical for genome stability. To understand whether cells carrying a functional repair apparatus are able to efficiently heal two distant chromosome ends and whether this DNA lesion might result in genome rearrangements, we induced DSBs in genetically modified mouse embryonic stem cells carrying two I-SceI sites in cis separated by a distance of 9 kbp. We show that in this context non-homologous end-joining (NHEJ) can repair using standard DNA pairing of the broken ends, but it also joins 3' non-complementary overhangs that require unusual joining intermediates. The repair efficiency of this lesion appears to be dramatically low and the extent of genome alterations was high in striking contrast with the spectra of repair events reported for two collinear DSBs in other experimental systems. The dramatic decline in accuracy suggests that significant constraints operate in the repair process of these distant DSBs, which may also control the low efficiency of this process. These findings provide important insights into the mechanism of repair by NHEJ and how this process may protect the genome from large rearrangements.

Structural dependences of localization and recombination of photogenerated carriers in the top GaInP Subcells of GaInP/GaAs double-junction tandem solar cells.

PubMed

Deng, Zhuo; Ning, Jiqiang; Su, Zhicheng; Xu, Shijie; Xing, Zheng; Wang, Rongxin; Lu, Shulong; Dong, Jianrong; Zhang, Baoshun; Yang, Hui

2015-01-14

In high-efficiency GaInP/GaAs double-junction tandem solar cells, GaInP layers play a central role in determining the performance of the solar cells. Therefore, gaining a deeper understanding of the optoelectronic processes in GaInP layers is crucial for improving the energy conversion efficiency of GaInP-based photovoltaic devices. In this work, we firmly show strong dependences of localization and recombination of photogenerated carriers in the top GaInP subcells in the GaInP/GaAs double-junction tandem solar cells on the substrate misorientation angle with excitation intensity- and temperature-dependent photoluminescence (PL). The entire solar cell structures including GaInP layers were grown with metalorganic chemical vapor deposition on GaAs substrates with misorientation angles of 2° (denoted as Sample 2°) and 7° (Sample 7°) off (100) toward (111)B. The PL spectral features of the two top GaInP subcells, as well as their excitation-power and temperature dependences exhibit remarkable variation on the misorientation angle. In Sample 2°, the dominant localization mechanism and luminescence channels are due to the energy potential minima caused by highly ordered atomic domains; In Sample 7°, the main localization and radiative recombination of photogenerated carriers occur in the atomically disordered regions. Our results reveal a more precise picture on the localization and recombination mechanisms of photogenerated carriers in the top GaInP subcells, which could be the crucial factors in controlling the optoelectronic efficiency of the GaInP-based multijunction photovoltaic devices.

A reversible fluorescent probe based on C[double bond, length as m-dash]N isomerization for the selective detection of formaldehyde in living cells and in vivo.

PubMed

Song, Xinyu; Han, Xiaoyue; Yu, Fabiao; Zhang, Jinjin; Chen, Lingxin; Lv, Changjun

2018-01-15

Formaldehyde (FA) is an endogenously produced reactive carbonyl species (RCS) through biological metabolic processes whose concentration is closely related to human health and disease. Noninvasive and real-time detection of FA concentration in organisms is very important for revealing the physiological and pathological functions of FA. Herein, we design and synthesize a reversible fluorescent probe BOD-NH 2 for the detection of FA in living cells and in vivo. The probe is composed of two moieties: the BODIPY fluorophore and the primary amino group response unit. The probe undergoes an intracellular aldimine condensation reaction with FA and forms imine (C[double bond, length as m-dash]N) which will result in C[double bond, length as m-dash]N isomerization and rotation to turn-off the fluorescence of the probe. It is important that the probe can show a reversible response to FA. The probe BOD-NH 2 has been successfully applied for detecting and imaging FA in the cytoplasm of living cells. BOD-NH 2 is capable of detecting fluctuations in the levels of endogenous and exogenous FA in different types of living cells. The probe can be used to visualize the FA concentration in fresh hippocampus and the probe can further qualitatively evaluate the FA concentrations in ex vivo-dissected organs. Moreover, BOD-NH 2 can also be used for imaging in mice. The above applications make our new probe a potential chemical tool for the study of physiological and pathological functions of FA in cells and in vivo.

In Vitro Expansion of Bone Marrow Derived Mesenchymal Stem Cells Alters DNA Double Strand Break Repair of Etoposide Induced DNA Damage.

PubMed

Hare, Ian; Gencheva, Marieta; Evans, Rebecca; Fortney, James; Piktel, Debbie; Vos, Jeffrey A; Howell, David; Gibson, Laura F

2016-01-01

Mesenchymal stem cells (MSCs) are of interest for use in diverse cellular therapies. Ex vivo expansion of MSCs intended for transplantation must result in generation of cells that maintain fidelity of critical functions. Previous investigations have identified genetic and phenotypic alterations of MSCs with in vitro passage, but little is known regarding how culturing influences the ability of MSCs to repair double strand DNA breaks (DSBs), the most severe of DNA lesions. To investigate the response to DSB stress with passage in vitro, primary human MSCs were exposed to etoposide (VP16) at various passages with subsequent evaluation of cellular damage responses and DNA repair. Passage number did not affect susceptibility to VP16 or the incidence and repair kinetics of DSBs. Nonhomologous end joining (NHEJ) transcripts showed little alteration with VP16 exposure or passage; however, homologous recombination (HR) transcripts were reduced following VP16 exposure with this decrease amplified as MSCs were passaged in vitro. Functional evaluations of NHEJ and HR showed that MSCs were unable to activate NHEJ repair following VP16 stress in cells after successive passage. These results indicate that ex vivo expansion of MSCs alters their ability to perform DSB repair, a necessary function for cells intended for transplantation.

MYC/BCL2/BCL6 triple hit lymphoma: a study of 40 patients with a comparison to MYC/BCL2 and MYC/BCL6 double hit lymphomas.

PubMed

Huang, Wenting; Medeiros, L Jeffrey; Lin, Pei; Wang, Wei; Tang, Guilin; Khoury, Joseph; Konoplev, Sergej; Yin, C Cameron; Xu, Jie; Oki, Yasuhiro; Li, Shaoying

2018-05-21

High-grade B-cell lymphomas with MYC, BCL2, and BCL6 rearrangements (triple hit lymphoma) are uncommon. We studied the clinicopathologic features of 40 patients with triple hit lymphoma and compared them to 157 patients with MYC/BCL2 double hit lymphoma and 13 patients with MYC/BCL6 double hit lymphoma. The triple hit lymphoma group included 25 men and 15 women with a median age of 61 years (range, 34-85). Nine patients had a history of B-cell lymphoma. Histologically, 23 (58%) cases were diffuse large B-cell lymphoma and 17 cases had features of B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma. Most cases of triple hit lymphoma were positive for CD10 (100%), BCL2 (95%), BCL6 (82%), MYC (74%), and 71% with MYC and BCL2 coexpression. P53 was overexpressed in 29% of triple hit lymphoma cases. The clinicopathological features of triple hit lymphoma patients were similar to patients with MYC/BCL2 and MYC/BCL6 double hit lymphoma, except that triple hit lymphoma cases were more often CD10 positive compared with MYC/BCL6 double hit lymphoma (p < 0.05). Induction chemotherapy used was similar for patients with triple hit lymphoma and double hit lymphoma and overall survival in triple hit lymphoma patients was 17.6 months, similar to the overall survival of patients with double hit lymphoma (p = 0.67). Patients with triple hit lymphoma showing P53 overexpression had significantly worse overall survival compared with those without P53 overexpression (p = 0.04). On the other hand, double expressor status and prior history of B-cell lymphoma did not correlate with overall survival. In conclusion, most patients with triple hit lymphoma have an aggressive clinical course and poor prognosis and these tumors have a germinal center B-cell immunophenotype, similar to patients with double hit lymphomas. P53 expression is a poor prognostic factor in patients with triple hit lymphoma.

Interplay between CedA, rpoB and double stranded DNA: A step towards understanding CedA mediated cell division in E. coli.

PubMed

Sharma, Pankaj; Tomar, Anil Kumar; Kundu, Bishwajit

2018-02-01

Cell division is compromised in DnaAcos mutant E. coli cells due to chromosome over-replication. In these cells, CedA acts as a regulatory protein and initiates cell division by a hitherto unknown mechanism. CedA, a double stranded DNA binding protein, interacts with various subunits of RNA polymerase complex, including rpoB. To reveal how this concert between CedA, rpoB and DNA brings about cell division in E. coli, we performed biophysical and in silico analysis and obtained mechanistic insights. Interaction between CedA and rpoB was shown by circular dichroism spectrometry and in silico docking experiments. Further, CedA and rpoB were allowed to interact individually to a selected DNA and their binding was monitored by fluorescence spectroscopy. The binding constants of these interactions as determined by BioLayer Interferometry clearly show that rpoB binds to DNA with higher affinity (K D2 =<1.0E-12M) as compared to CedA (K D2 =9.58E-09M). These findings were supported by docking analysis where 12 intermolecular H-bonds were formed in rpoB-DNA complex as compared to 4 in CedA-DNA complex. Based on our data we propose that in E. coli cells chromosome over-replication signals CedA to recruit rpoB to specific DNA site(s), which initiates transcription of cell division regulatory elements. Copyright © 2017 Elsevier B.V. All rights reserved.

Allogeneic Mesenchymal Stem Cells Ameliorate Aging Frailty: A Phase II Randomized, Double-Blind, Placebo-Controlled Clinical Trial

PubMed Central

Tompkins, Bryon A; DiFede, Darcy L; Khan, Aisha; Landin, Ana Marie; Schulman, Ivonne Hernandez; Pujol, Marietsy V; Heldman, Alan W; Miki, Roberto; Goldschmidt-Clermont, Pascal J; Goldstein, Bradley J; Mushtaq, Muzammil; Levis-Dusseau, Silvina; Byrnes, John J; Lowery, Maureen; Natsumeda, Makoto; Delgado, Cindy; Saltzman, Russell; Vidro-Casiano, Mayra; Da Fonseca, Moisaniel; Golpanian, Samuel; Premer, Courtney; Medina, Audrey; Valasaki, Krystalenia; Florea, Victoria; Anderson, Erica; El-Khorazaty, Jill; Mendizabal, Adam; Green, Geoff; Oliva, Anthony A; Hare, Joshua M

2017-01-01

Abstract Background Aging frailty, characterized by decreased physical and immunological functioning, is associated with stem cell depletion. Human allogeneic mesenchymal stem cells (allo-hMSCs) exert immunomodulatory effects and promote tissue repair. Methods This is a randomized, double-blinded, dose-finding study of intravenous allo-hMSCs (100 or 200-million [M]) vs placebo delivered to patients (n = 30, mean age 75.5 ± 7.3) with frailty. The primary endpoint was incidence of treatment-emergent serious adverse events (TE-SAEs) at 1-month postinfusion. Secondary endpoints included physical performance, patient-reported outcomes, and immune markers of frailty measured at 6 months postinfusion. Results No therapy-related TE-SAEs occurred at 1 month. Physical performance improved preferentially in the 100M-group; immunologic improvement occurred in both the 100M- and 200M-groups. The 6-minute walk test, short physical performance exam, and forced expiratory volume in 1 second improved in the 100M-group (p = .01), not in the 200M- or placebo groups. The female sexual quality of life questionnaire improved in the 100M-group (p = .03). Serum TNF-α levels decreased in the 100M-group (p = .03). B cell intracellular TNF-α improved in both the 100M- (p < .0001) and 200M-groups (p = .002) as well as between groups compared to placebo (p = .003 and p = .039, respectively). Early and late activated T-cells were also reduced by MSC therapy. Conclusion Intravenous allo-hMSCs were safe in individuals with aging frailty. Treated groups had remarkable improvements in physical performance measures and inflammatory biomarkers, both of which characterize the frailty syndrome. Given the excellent safety and efficacy profiles demonstrated in this study, larger clinical trials are warranted to establish the efficacy of hMSCs in this multisystem disorder. Clinical Trial Registration www.clinicaltrials.gov: CRATUS (#NCT02065245). PMID:28977399

Double-strand break repair-adox: Restoration of suppressed double-strand break repair during mitosis induces genomic instability

PubMed Central

Terasawa, Masahiro; Shinohara, Akira; Shinohara, Miki

2014-01-01

Double-strand breaks (DSBs) are one of the severest types of DNA damage. Unrepaired DSBs easily induce cell death and chromosome aberrations. To maintain genomic stability, cells have checkpoint and DSB repair systems to respond to DNA damage throughout most of the cell cycle. The failure of this process often results in apoptosis or genomic instability, such as aneuploidy, deletion, or translocation. Therefore, DSB repair is essential for maintenance of genomic stability. During mitosis, however, cells seem to suppress the DNA damage response and proceed to the next G1 phase, even if there are unrepaired DSBs. The biological significance of this suppression is not known. In this review, we summarize recent studies of mitotic DSB repair and discuss the mechanisms of suppression of DSB repair during mitosis. DSB repair, which maintains genomic integrity in other phases of the cell cycle, is rather toxic to cells during mitosis, often resulting in chromosome missegregation and aberration. Cells have multiple safeguards to prevent genomic instability during mitosis: inhibition of 53BP1 or BRCA1 localization to DSB sites, which is important to promote non-homologous end joining or homologous recombination, respectively, and also modulation of the non-homologous end joining core complex to inhibit DSB repair. We discuss how DSBs during mitosis are toxic and the multiple safeguard systems that suppress genomic instability. PMID:25287622

Linearity can account for the similarity among conventional, frequency-doubling, and gabor-based perimetric tests in the glaucomatous macula.

PubMed

Sun, Hao; Dul, Mitchell W; Swanson, William H

2006-07-01

The purposes of this study are to compare macular perimetric sensitivities for conventional size III, frequency-doubling, and Gabor stimuli in terms of Weber contrast and to provide a theoretical interpretation of the results. Twenty-two patients with glaucoma performed four perimetric tests: a conventional Swedish Interactive Threshold Algorithm (SITA) 10-2 test with Goldmann size III stimuli, two frequency-doubling tests (FDT 10-2, FDT Macula) with counterphase-modulated grating stimuli, and a laboratory-designed test with Gabor stimuli. Perimetric sensitivities were converted to the reciprocal of Weber contrast and sensitivities from different tests were compared using the Bland-Altman method. Effects of ganglion cell loss on perimetric sensitivities were then simulated with a two-stage neural model. The average perimetric loss was similar for all stimuli until advanced stages of ganglion cell loss, in which perimetric loss tended to be greater for size III stimuli than for frequency-doubling and Gabor stimuli. Comparison of the experimental data and model simulation suggests that, in the macula, linear relations between ganglion cell loss and perimetric sensitivity loss hold for all three stimuli. Linear relations between perimetric loss and ganglion cell loss for all three stimuli can account for the similarity in perimetric loss until advanced stages. The results do not support the hypothesis that redundancy for frequency-doubling stimuli is lower than redundancy for size III stimuli.

Bioinspired metal-cell wall-metal sandwich structure on an individual bacterial cell scaffold.

PubMed

Zhang, Xiaoliang; Yu, Mei; Liu, Jianhua; Li, Songmei

2012-08-25

Pd nanoparticles were introduced to individual Bacillus cells and dispersedly anchored on both the inside and outside of the cell walls. The anchored nanoparticles served as "seeds" to drive the formation of double metallic layers forming a metal-cell wall-metal sandwich structure at the single-cell level.

Correlations between radiation-induced double strand breaks, cell division delay, and cyclin-dependent signaling in x-irradiated NIH3T3 fibroblasts

NASA Astrophysics Data System (ADS)

Cariveau, Mickael J.

2005-07-01

Molecular responses to radiation-induced DNA double strand breaks (DSB) are mediated by the phosphorylation of the histone variant H2AX which forms identifiable gamma-H2AX foci at the site of the DSB. This event is thought to be linked with the down-regulation of signaling proteins contributing to the checkpoints regulating cell cycle progression and, vis-a-vis , the induction of cell division delay. However, it is unclear whether this division delay is directly related to the number of DSB (gamma-H2AX foci) sustained by an irradiated cell and, if so, whether this number drives cells into cell cycle delay or apoptosis. For this reason, studies were conducted in the immortalized NIH/3T3 fibroblast cell in order to establish correlations between the temporal appearance of the gamma-H2AX foci (a DSB) and the expression of the cell cycle regulatory proteins, cyclin E, A, B1, and their cyclin kinase inhibitor, p21. Cell cycle kinetics and flow cytometry were used to establish radiation-induced division delay over a dose range of 1--6 Gy where a mitotic delay of 2.65 min/cGy was established. Correlations between the expression of cyclin E, A, B1, p21, and the generation of DSB were established in NIH/3T3 cells exposed to 2 or 4 Gy x-irradiation. The data suggest that the G1/S and S phase delay (cyclin E and cyclin A protein levels) are dependent on the dose of radiation while the G2/M (cyclin B1 protein levels) delay is dependent on the quantity of DSB sustained by the irradiated cell.

Synthesis, biological evaluation, and structure-activity relationships of novel substituted N-phenyl ureidobenzenesulfonate derivatives blocking cell cycle progression in S-phase and inducing DNA double-strand breaks.

PubMed

Turcotte, Vanessa; Fortin, Sébastien; Vevey, Florence; Coulombe, Yan; Lacroix, Jacques; Côté, Marie-France; Masson, Jean-Yves; C-Gaudreault, René

2012-07-12

Twenty-eight new substituted N-phenyl ureidobenzenesulfonate (PUB-SO) and 18 N-phenylureidobenzenesulfonamide (PUB-SA) derivatives were prepared. Several PUB-SOs exhibited antiproliferative activity at the micromolar level against the HT-29, M21, and MCF-7 cell lines and blocked cell cycle progression in S-phase similarly to cisplatin. In addition, PUB-SOs induced histone H2AX (γH2AX) phosphorylation, indicating that these molecules induce DNA double-strand breaks. In contrast, PUB-SAs were less active than PUB-SOs and did not block cell cycle progression in S-phase. Finally, PUB-SOs 4 and 46 exhibited potent antitumor activity in HT-1080 fibrosarcoma cells grafted onto chick chorioallantoic membranes, which was similar to cisplatin and combretastatin A-4 and without significant toxicity toward chick embryos. These new compounds are members of a promising new class of anticancer agents.

Electrochemical cell

DOEpatents

Redey, L.I.; Myles, K.M.; Vissers, D.R.; Prakash, J.

1996-07-02

An electrochemical cell is described with a positive electrode having an electrochemically active layer of at least one transition metal chloride. A negative electrode of an alkali metal and a compatible electrolyte including an alkali metal salt molten at cell operating temperature is included in the cell. The electrolyte is present at least partially as a corrugated {beta}{double_prime} alumina tube surrounding the negative electrode interior to the positive electrode. The ratio of the volume of liquid electrolyte to the volume of the positive electrode is in the range of from about 0.1 to about 3. A plurality of stacked electrochemical cells is disclosed each having a positive electrode, a negative electrode of an alkali metal molten at cell operating temperature, and a compatible electrolyte. The electrolyte is at least partially present as a corrugated {beta}{double_prime} alumina sheet separating the negative electrode and interior to the positive electrodes. The alkali metal is retained in a porous electrically conductive ceramic, and seals for sealing the junctures of the electrolyte and the adjacent electrodes at the peripheries thereof. 8 figs.

Solubility of HCL in sulfuric acid at stratospheric temperatures

NASA Technical Reports Server (NTRS)

Williams, Leah R.; Golden, David M.

1993-01-01

The solubility of HCl in sulfuric acid was measured using a Knudsen cell technique. Effective Henry's law constants are reported for sulfuric acid concentrations between 50 and 60 weight percent and for temperatures between 220 and 230 K. The measured values indicate that very little HCl will be dissolved in the stratospheric sulfate aerosol particles.

Structural and mechanistic insights into Mcm2-7 double-hexamer assembly and function

DOE PAGES

Sun, Jingchuan; Li, Huilin; Fernandez-Cid, Alejandra; ...

2014-10-15

Eukaryotic cells license each DNA replication origin during G1 phase by assembling a prereplication complex that contains a Mcm2–7 (minichromosome maintenance proteins 2–7) double hexamer. During S phase, each Mcm2–7 hexamer forms the core of a replicative DNA helicase. However, the mechanisms of origin licensing and helicase activation are poorly understood. The helicase loaders ORC–Cdc6 function to recruit a single Cdt1–Mcm2–7 heptamer to replication origins prior to Cdt1 release and ORC–Cdc6–Mcm2–7 complex formation, but how the second Mcm2–7 hexamer is recruited to promote double-hexamer formation is not well understood. Here, structural evidence for intermediates consisting of an ORC–Cdc6–Mcm2–7 complex andmore » an ORC–Cdc6–Mcm2–7–Mcm2–7 complex are reported, which together provide new insights into DNA licensing. Detailed structural analysis of the loaded Mcm2–7 double-hexamer complex demonstrates that the two hexamers are interlocked and misaligned along the DNA axis and lack ATP hydrolysis activity that is essential for DNA helicase activity. Moreover, we show that the head-to-head juxtaposition of the Mcm2–7 double hexamer generates a new protein interaction surface that creates a multisubunit-binding site for an S-phase protein kinase that is known to activate DNA replication. The data suggest how the double hexamer is assembled and how helicase activity is regulated during DNA licensing, with implications for cell cycle control of DNA replication and genome stability.« less

The double-stranded RNA binding protein RDE-4 can act cell autonomously during feeding RNAi in C. elegans.

PubMed

Raman, Pravrutha; Zaghab, Soriayah M; Traver, Edward C; Jose, Antony M

2017-08-21

Long double-stranded RNA (dsRNA) can silence genes of matching sequence upon ingestion in many invertebrates and is therefore being developed as a pesticide. Such feeding RNA interference (RNAi) is best understood in the worm Caenorhabditis elegans, where the dsRNA-binding protein RDE-4 initiates silencing by recruiting an endonuclease to process long dsRNA into short dsRNA. These short dsRNAs are thought to move between cells because muscle-specific rescue of rde-4 using repetitive transgenes enables silencing in other tissues. Here, we extend this observation using additional promoters, report an inhibitory effect of repetitive transgenes, and discover conditions for cell-autonomous silencing in animals with tissue-specific rescue of rde-4. While expression of rde-4(+) in intestine, hypodermis, or neurons using a repetitive transgene can enable silencing also in unrescued tissues, silencing can be inhibited wihin tissues that express a repetitive transgene. Single-copy transgenes that express rde-4(+) in body-wall muscles or hypodermis, however, enable silencing selectively in the rescued tissue but not in other tissues. These results suggest that silencing by the movement of short dsRNA between cells is not an obligatory feature of feeding RNAi in C. elegans. We speculate that similar control of dsRNA movement could modulate tissue-specific silencing by feeding RNAi in other invertebrates. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

The concept of double inlet-double outlet right ventricle: a distinct congenital heart disease.

PubMed

Spadotto, Veronica; Frescura, Carla; Ho, Siew Yen; Thiene, Gaetano

The aim of this study was to estimate the incidence and to analyze the anatomy of double inlet-double outlet right ventricle complex and its associated cardiac anomalies in our autopsy series. Among the 1640 hearts with congenital heart disease of our Anatomical Collection, we reviewed the specimens with double inlet-double outlet right ventricle, according to the sequential-segmental analysis, identifying associated cardiac anomalies and examining lung histology to assess the presence of pulmonary vascular disease. We identified 14 hearts with double inlet-double outlet right ventricle (0.85%). Right atrial isomerism was observed in 10 hearts, situs solitus in 3 and left atrial isomerism in one. Regarding the mode of atrioventricular connection, all hearts but one had a common atrioventricular valve. Systemic or pulmonary venous abnormalities were noted in all patients with atrial isomerism. In nine patients a valvular or subvalvular pulmonary stenosis was present. Among the functionally "univentricular hearts", double inlet- double outlet right ventricle represents a peculiar entity, mostly in association with right atrial isomerism. Multiple cardiac anomalies are associated and may complicate surgical repair. Copyright © 2016 Elsevier Inc. All rights reserved.

Heat exposure enhances radiosensitivity by depressing DNA-PK kinase activity during double strand break repair.

PubMed

Ihara, Makoto; Takeshita, Satoshi; Okaichi, Kumio; Okumura, Yutaka; Ohnishi, Takeo

2014-03-01

From the role of double strand DNA dependent protein kinase (DNA-PKcs) activity of non-homologous end joining (NHEJ) repair for DNA double strand breaks (DSBs), we aim to define possible associations between thermo-sensitisation and the enzyme activities in X-ray irradiated cells. DNA-PKcs deficient mouse, Chinese hamster and human cultured cells were compared to the parental wild-type cells. The radiosensitivities, the number of DSBs and DNA-PKcs activities after heat-treatment were measured. Both DNA-PKcs deficient cells and the wild-type cells showed increased radiosensitivities after heat-treatment. The wild-type cells have two repair processes; fast repair and slow repair. In contrast, DNA-PKcs deficient cells have only the slow repair process. The fast repair component apparently disappeared by heat-treatment in the wild-type cells. In both cell types, additional heat exposure enhanced radiosensitivities. Although DNA-PKcs activity was depressed by heat, the inactivated DNA-PKcs activity recovered during an incubation at 37 °C. DSB repair efficiency was dependent on the reactivation of DNA-PKcs activity. It was suggested that NHEJ is the major process used to repair X-ray-induced DSBs and utilises DNA-PKcs activity, but homologous recombination repair provides additional secondary levels of DSB repair. The thermo-sensitisation in X-ray-irradiated cells depends on the inhibition of NHEJ repair through the depression of DNA-PKcs activities.

PI3K-delta mediates double-stranded RNA-induced upregulation of B7-H1 in BEAS-2B airway epithelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kan-o, Keiko; Matsumoto, Koichiro, E-mail: koichi@kokyu.med.kyushu-u.ac.jp; Asai-Tajiri, Yukari

Highlights: •Double-stranded RNA upregulates B7-H1 on BEAS-2B airway epithelial cells. •The upregulation of B7-H1 is attenuated by inhibition of PI3Kδ isoform. •PI3Kδ-mediated upregulation of B7-H1 is independent of NF-κB activation. •Inhibition of PI3Kδ may prevent persistent viral infection induced by B7-H1. -- Abstract: Airway viral infection disturbs the health-related quality of life. B7-H1 (also known as PD-L1) is a coinhibitory molecule associated with the escape of viruses from the mucosal immunity, leading to persistent infection. Most respiratory viruses generate double-stranded (ds) RNA during replication. The stimulation of cultured airway epithelial cells with an analog of viral dsRNA, polyinosinic-polycytidylic acid (polymore » IC) upregulates the expression of B7-H1 via activation of the nuclear factor κB(NF-κB). The mechanism of upregulation was investigated in association with phosphatidylinositol 3-kinases (PI3Ks). Poly IC-induced upregulation of B7-H1 was profoundly suppressed by a pan-PI3K inhibitor and partially by an inhibitor or a small interfering (si)RNA for PI3Kδ in BEAS-2B cells. Similar results were observed in the respiratory syncytial virus-infected cells. The expression of p110δ was detected by Western blot and suppressed by pretreatment with PI3Kδ siRNA. The activation of PI3Kδ is typically induced by oxidative stress. The generation of reactive oxygen species was increased by poly IC. Poly IC-induced upregulation of B7-H1 was attenuated by N-acetyl-L-cysteine, an antioxidant, or by oxypurinol, an inhibitor of xanthine oxidase. Poly IC-induced activation of NF-κB was suppressed by a pan-PI3K inhibitor but not by a PI3Kδ inhibitor. These results suggest that PI3Kδ mediates dsRNA-induced upregulation of B7-H1 without affecting the activation of NF-κB.« less

Meiotic Recombination Initiated by a Double-Strand Break in Rad50Δ Yeast Cells Otherwise Unable to Initiate Meiotic Recombination

PubMed Central

Malkova, A.; Ross, L.; Dawson, D.; Hoekstra, M. F.; Haber, J. E.

1996-01-01

Meiotic recombination in Saccharomyces cerevisiae is initiated by double-strand breaks (DSBs). We have developed a system to compare the properties of meiotic DSBs with those created by the site-specific HO endonuclease. HO endonuclease was expressed under the control of the meiotic-specific SPO13 promoter, creating a DSB at a single site on one of yeast's 16 chromosomes. In Rad(+) strains the times of appearance of the HO-induced DSBs and of subsequent recombinants are coincident with those induced by normal meiotic DSBs. Physical monitoring of DNA showed that SPO13::HO induced gene conversions both in Rad(+) and in rad50Δ cells that cannot initiate normal meiotic DSBs. We find that the RAD50 gene is important, but not essential, for recombination even after a DSB has been created in a meiotic cell. In rad50Δ cells, some DSBs are not repaired until a broken chromosome has been packaged into a spore and is subsequently germinated. This suggests that a broken chromosome does not signal an arrest of progression through meiosis. The recombination defect in rad50Δ diploids is not, however, meiotic specific, as mitotic rad50 diploids, experiencing an HO-induced DSB, exhibit similar departures from wild-type recombination. PMID:8725223

Stalk cell differentiation without polyketides in the cellular slime mold.

PubMed

Sato, Yukie G; Suarez, Teresa; Saito, Tamao

2016-07-01

Polyketides induce prestalk cell differentiation in Dictyostelium. In the double-knockout mutant of the SteelyA and B polyketide synthases, most of the pstA cells-the major part of the prestalk cells-are lost, and we show by whole mount in situ hybridization that expression of prestalk genes is also reduced. Treatment of the double-knockout mutant with the PKS inhibitor cerulenin gave a further reduction, but some pstA cells still remained in the tip region, suggesting the existence of a polyketide-independent subtype of pstA cells. The double-knockout mutant and cerulenin-treated parental Ax2 cells form fruiting bodies with fragile, single-cell layered stalks after cerulenin treatment. Our results indicate that most pstA cells are induced by polyketides, but the pstA cells at the very tip of the slug are induced in some other way. In addition, a fruiting body with a single-cell layered, vacuolated stalk can form without polyketides.

Ionic Liquids as Electrolytes for Electrochemical Double-Layer Capacitors: Structures that Optimize Specific Energy.

PubMed

Mousavi, Maral P S; Wilson, Benjamin E; Kashefolgheta, Sadra; Anderson, Evan L; He, Siyao; Bühlmann, Philippe; Stein, Andreas

2016-02-10

Key parameters that influence the specific energy of electrochemical double-layer capacitors (EDLCs) are the double-layer capacitance and the operating potential of the cell. The operating potential of the cell is generally limited by the electrochemical window of the electrolyte solution, that is, the range of applied voltages within which the electrolyte or solvent is not reduced or oxidized. Ionic liquids are of interest as electrolytes for EDLCs because they offer relatively wide potential windows. Here, we provide a systematic study of the influence of the physical properties of ionic liquid electrolytes on the electrochemical stability and electrochemical performance (double-layer capacitance, specific energy) of EDLCs that employ a mesoporous carbon model electrode with uniform, highly interconnected mesopores (3DOm carbon). Several ionic liquids with structurally diverse anions (tetrafluoroborate, trifluoromethanesulfonate, trifluoromethanesulfonimide) and cations (imidazolium, ammonium, pyridinium, piperidinium, and pyrrolidinium) were investigated. We show that the cation size has a significant effect on the electrolyte viscosity and conductivity, as well as the capacitance of EDLCs. Imidazolium- and pyridinium-based ionic liquids provide the highest cell capacitance, and ammonium-based ionic liquids offer potential windows much larger than imidazolium and pyridinium ionic liquids. Increasing the chain length of the alkyl substituents in 1-alkyl-3-methylimidazolium trifluoromethanesulfonimide does not widen the potential window of the ionic liquid. We identified the ionic liquids that maximize the specific energies of EDLCs through the combined effects of their potential windows and the double-layer capacitance. The highest specific energies are obtained with ionic liquid electrolytes that possess moderate electrochemical stability, small ionic volumes, low viscosity, and hence high conductivity, the best performing ionic liquid tested being 1-ethyl-3

Differential tumor biology effects of double-initiation in a mouse skin chemical carcinogenesis model comparing wild type versus protein kinase Cepsilon overexpression mice.

PubMed

Li, Yafan; Wheeler, Deric L; Ananthaswamy, Honnavara N; Verma, Ajit K; Oberley, Terry D

2007-12-01

Our previous studies showed that protein kinase Cepsilon (PKCepsilon) verexpression in mouse skin resulted in metastatic squamous cell carcinoma (SCC) elicited by single 7,12-dimethylbenz(a)anthracene (DMBA)-initiation and 12-O-tetradecanoylphorbol-13-acetate (TPA)-promotion in the absence of preceding papilloma formation as is typically observed in wild type mice. The present study demonstrates that double-DMBA initiation modulates tumor incidence, multiplicity, and latency period in both wild type and PKCepsilon overexpression transgenic (PKCepsilon-Tg) mice. After 17 weeks (wks) of tumor promotion, a reduction in papilloma multiplicity was observed in double- versus single-DMBA initiated wild type mice. Papilloma multiplicity was inversely correlated with cell death indices of interfollicular keratinocytes, indicating decreased papilloma formation was caused by increased cell death and suggesting the origin of papillomas is in interfollicular epidermis. Double-initiated PKCepsilon-Tg mice had accelerated carcinoma formation and cancer incidence in comparison to single-initiated PKCepsilon-Tg mice. Morphologic analysis of mouse skin following double initiation and tumor promotion showed a similar if not identical series of events to those previously observed following single initiation and tumor promotion: putative preneoplastic cells were observed arising from hyperplastic hair follicles (HFs) with subsequent cancer cell infiltration into the dermis. Single-initiated PKCepsilon-Tg mice exhibited increased mitosis in epidermal cells of HFs during tumor promotion.

The Hinge Region as a Key Regulatory Element of Androgen Receptor Dimerization, DNA Binding, and Transactivation

DTIC Science & Technology

2005-05-01

an impaired activity (see report of 2003). We obtained an EGFP fusion from Dr. Karen Knudsen (Ohio University, Cincinatti) in which a Gly-Ala linker ... Smad3 after its acetylation. The mutation of this lysine to glutamine or threonine (mimics acetylation), when expressed in DU145 cells promoted cell...forms. A Gly-Ala linker between the two proteins is necessary, since a direct fusion protein was largely impaired in its activity (not shown). 6. The

Splicing stimulates siRNA formation at Drosophila DNA double-strand breaks

PubMed Central

Merk, Karin; Breinig, Marco; Böttcher, Romy; Krebs, Stefan; Blum, Helmut; Boutros, Michael

2017-01-01

DNA double-strand breaks trigger the production of locus-derived siRNAs in fruit flies, human cells and plants. At least in flies, their biogenesis depends on active transcription running towards the break. Since siRNAs derive from a double-stranded RNA precursor, a major question is how broken DNA ends can generate matching sense and antisense transcripts. We performed a genome-wide RNAi-screen in cultured Drosophila cells, which revealed that in addition to DNA repair factors, many spliceosome components are required for efficient siRNA generation. We validated this observation through site-specific DNA cleavage with CRISPR-cas9 followed by deep sequencing of small RNAs. DNA breaks in intron-less genes or upstream of a gene’s first intron did not efficiently trigger siRNA production. When DNA double-strand breaks were induced downstream of an intron, however, this led to robust siRNA generation. Furthermore, a downstream break slowed down splicing of the upstream intron and a detailed analysis of siRNA coverage at the targeted locus revealed that unspliced pre-mRNA contributes the sense strand to the siRNA precursor. Since splicing factors are stimulating the response but unspliced transcripts are entering the siRNA biogenesis, the spliceosome is apparently stalled in a pre-catalytic state and serves as a signaling hub. We conclude that convergent transcription at DNA breaks is stimulated by a splicing dependent control process. The resulting double-stranded RNA is converted into siRNAs that instruct the degradation of cognate mRNAs. In addition to a potential role in DNA repair, the break-induced transcription may thus be a means to cull improper RNAs from the transcriptome of Drosophila melanogaster. Since the splicing factors identified in our screen also stimulated siRNA production from high copy transgenes, it is possible that this surveillance mechanism serves in genome defense beyond DNA double-strand breaks. PMID:28628606

GC-Rich Extracellular DNA Induces Oxidative Stress, Double-Strand DNA Breaks, and DNA Damage Response in Human Adipose-Derived Mesenchymal Stem Cells.

PubMed

Kostyuk, Svetlana; Smirnova, Tatiana; Kameneva, Larisa; Porokhovnik, Lev; Speranskij, Anatolij; Ershova, Elizaveta; Stukalov, Sergey; Izevskaya, Vera; Veiko, Natalia

2015-01-01

Cell free DNA (cfDNA) circulates throughout the bloodstream of both healthy people and patients with various diseases. CfDNA is substantially enriched in its GC-content as compared with human genomic DNA. Exposure of haMSCs to GC-DNA induces short-term oxidative stress (determined with H2DCFH-DA) and results in both single- and double-strand DNA breaks (comet assay and γH2AX, foci). As a result in the cells significantly increases the expression of repair genes (BRCA1 (RT-PCR), PCNA (FACS)) and antiapoptotic genes (BCL2 (RT-PCR and FACS), BCL2A1, BCL2L1, BIRC3, and BIRC2 (RT-PCR)). Under the action of GC-DNA the potential of mitochondria was increased. Here we show that GC-rich extracellular DNA stimulates adipocyte differentiation of human adipose-derived mesenchymal stem cells (haMSCs). Exposure to GC-DNA leads to an increase in the level of RNAPPARG2 and LPL (RT-PCR), in the level of fatty acid binding protein FABP4 (FACS analysis) and in the level of fat (Oil Red O). GC-rich fragments in the pool of cfDNA can potentially induce oxidative stress and DNA damage response and affect the direction of mesenchymal stem cells differentiation in human adipose-derived mesenchymal stem cells. Such a response may be one of the causes of obesity or osteoporosis.

Concurrent inhibition of MYC and BCL2 is a potentially effective treatment strategy for double hit and triple hit B-cell lymphomas.

PubMed

Cinar, Munevver; Rosenfelt, Fred; Rokhsar, Sepehr; Lopategui, Jean; Pillai, Raju; Cervania, Melissa; Pao, Andy; Cinar, Bekir; Alkan, Serhan

2015-07-01

Double hit lymphoma or triple hit lymphoma (DHL/THL) is a rare form of aggressive B-Cell Lymphoma. Overexpression of MYC, BCL2 or/and BCL6 due to genomic rearrangements are the key molecular features of DHL/THL. Patients with DHL/THL show very aggressive disease course and poor survival due to the lack of effective treatment modalities. Here, we established new THL cell model and assessed its in vitro growth characteristics along with the DHL cell line in response to potent MYC inhibitors, 10058-F4 and JQ-1, and a BCL2 inhibitor, ABT-199, with or without chemotherapeutic agent vincristine or doxorubicin. We found that 10058-F4, JQ-1 or ABT-199 exposure as a single agent inhibited the growth of DHL/THL cells in a dose-dependent manner. Combined exposure of 10058-F4 or JQ-1 and ABT-199 as well as vincristine or doxorubicin markedly suppressed the growth of DHL/THL cells compared with the single treatment. As assessed by multiple approaches, apoptosis induced by ABT-199, 10058-F4 or JQ-1 was underlying cause of the observed growth suppression. These findings suggest that co-inhibition of MYC and BCL2 signaling is a promising therapeutic strategy for patients with DHL/THL lymphomas. Copyright © 2015 Elsevier Ltd. All rights reserved.

Scaling of volume to surface ratio and doubling time in growing unicellular organisms: Do cells appear quantum-mechanical systems?

NASA Astrophysics Data System (ADS)

Atanasov, Atanas Todorov

2014-10-01

The scaling of physical and biological characteristics of the living organisms is a basic method for searching of new biophysical laws. In series of previous studies the author showed that in Poikilotherms, Mammals and Aves, the volume to surface ratio V×S-1 (m) of organisms is proportional to their generation time Tgt(s) via growth rate v (m s-1): V×S-1 = vgr×Tr. The power and the correlation coefficients are near to 1.0. Aim of this study is: i) to prove with experimental data the validity of the above equation for Unicellular organisms and ii) to show that perhaps, the cells are quantum-mechanical systems. The data for body mass M (kg), density ρ (kg/m3), minimum and maximum doubling time Tdt (s) for 50 unicellular organisms are assembled from scientific sources, and the computer program `Statistics' is used for calculations. In result i) the analytical relationship from type: V×S-1 = 4.46ṡ10-11×Tdt was found, where vgr = 4.46×10-11 m/s and ii) it is shown that the products between cell mass M, cell length expressed by V/S ratio and growth rate vgr satisfied the Heisenberg uncertainty principle i.e. the inequalities V/S×M×vgr>h/2π and Tdt×M×vgr2>h/2π are valid, where h= 6.626×10-34 Jṡs is the Planck constant. This rise the question: do cells appear quantum-mechanical systems?

Double emulsion electrospun nanofibers as a growth factor delivery vehicle for salivary gland regeneration

NASA Astrophysics Data System (ADS)

Foraida, Zahraa I.; Sharikova, Anna; Peerzada, Lubna N.; Khmaladze, Alexander; Larsen, Melinda; Castracane, James

2017-08-01

Sustained delivery of growth factors, proteins, drugs and other biologically active molecules is necessary for tissue engineering applications. Electrospun fibers are attractive tissue engineering scaffolds as they partially mimic the topography of the extracellular matrix (ECM). However, they do not provide continuous nourishment to the tissue. In search of a biomimetic scaffold for salivary gland tissue regeneration, we previously developed a blend nanofiber scaffold composed of the protein elastin and the synthetic polymer polylactic-co-glycolic acid (PLGA). The nanofiber scaffold promoted in vivo-like salivary epithelial cell tissue organization and apicobasal polarization. However, in order to enhance the salivary cell proliferation and biomimetic character of the scaffold, sustained growth factor delivery is needed. The composite nanofiber scaffold was optimized to act as a growth factor delivery system using epidermal growth factor (EGF) as a model protein. The nanofiber/EGF hybrid nanofibers were synthesized by double emulsion electrospinning where EGF is emulsified within a water/oil/water (w/o/w) double emulsion system. Successful incorporation of EGF was confirmed using Raman spectroscopy. EGF release profile was characterized using enzyme-linked immunosorbent assay (ELIZA) of the EGF content. Double emulsion electrospinning resulted in slower release of EGF. We demonstrated the potential of the proposed double emulsion electrospun nanofiber scaffold for the delivery of growth factors and/or drugs for tissue engineering and pharmaceutical applications.

Lamb wave band gaps in a double-sided phononic plate

NASA Astrophysics Data System (ADS)

Wang, Peng; Chen, Tian-Ning; Yu, Kun-Peng; Wang, Xiao-Peng

2013-02-01

In this paper, we report on the theoretical investigation of the propagation characteristics of Lamb wave in a phononic crystal structure constituted by a square array of cylindrical stubs deposited on both sides of a thin homogeneous plate. The dispersion relations, the power transmission spectra, and the displacement fields of the eigenmodes are studied by using the finite-element method. We investigate the evolution of band gaps in the double-sided phononic plate with stub height on both sides arranged from an asymmetrical distribution to a symmetrical distribution gradually. Numerical results show that as the double stubs in a unit cell arranged more symmetrically on both sides, band width shifts, new band gaps appear, and the bands become flat due to localized resonant modes which couple with plate modes. Specially, more band gaps and flat bands can be found in the symmetrical system as a result of local resonances of the stubs which interact in a stronger way with the plate modes. Moreover, the symmetrical double-sided plate exhibits lower and smaller band gap than that of the asymmetrical plate. These propagation properties of elastic or acoustic waves in the double-sided plate can potentially be utilized to generate filters, slow the group velocity, low-frequency sound insulation, and design acoustic sensors.

Double emulsions based on silicone-fluorocarbon-water and their skin penetration.

PubMed

Mahrhauser, Denise-Silvia; Fischer, Claudia; Valenta, Claudia

2016-02-10

Double emulsions have significant potential in pharmacy and cosmetics due to the feasibility of combining incompatible substances in one product and the protection of sensitive compounds by incorporating them into their innermost phase. However, a major drawback of double emulsions is their thermodynamic instability and their strong tendency to coalesce. In the present study, the physicochemical stability, the skin permeation and the skin penetration potential of modified semi-solid double emulsions was investigated. The double emulsions were prepared of the cosmetically applied perfluoropolyethers Fomblin HC/04 or Fomblin HC-OH, silicone, carbomer and water. Measurement of the droplet size and examination of the microscopic images confirmed their physicochemical stability over the observation period of eight weeks. Franz-type diffusion cell experiments revealed no increase in curcumin permeation due to the employed perfluoropolyethers compared to the respective control formulations. The formulations used as control were O/W macroemulsions with or without a Polysorbate 80/Sorbitane monooleate 80 surfactant combination. Likewise, tape stripping studies showed no penetration enhancing effect of the employed perfluoropolyethers which is desirable as both perfluoropolyethers are commonly applied components in human personal-care products. Copyright © 2015 Elsevier B.V. All rights reserved.

Flexible DNA Path in the MCM Double Hexamer Loaded on DNA.

PubMed

Hizume, Kohji; Kominami, Hiroaki; Kobayashi, Kei; Yamada, Hirofumi; Araki, Hiroyuki

2017-05-16

The formation of the pre-replicative complex (pre-RC) during the G1 phase, which is also called the licensing of DNA replication, is the initial and essential step of faithful DNA replication during the subsequent S phase. It is widely accepted that in the pre-RC, double-stranded DNA passes through the holes of two ring-shaped minichromosome maintenance (MCM) 2-7 hexamers; however, the spatial organization of the DNA and proteins involved in pre-RC formation is unclear. Here we reconstituted the pre-RC from purified DNA and proteins and visualized the complex using atomic force microscopy (AFM). AFM revealed that the MCM double hexamers formed elliptical particles on DNA. Analysis of the angle of binding of DNA to the MCM double hexamer suggests that the DNA does not completely pass through both holes of the MCM hexamers, possibly because the DNA exited from the gap between Mcm2 and Mcm5. A DNA loop fastened by the MCM double hexamer was detected in pre-RC samples reconstituted from purified proteins as well as those purified from yeast cells, suggesting a higher-order architecture of the loaded MCM hexamers and DNA strands.

Seeing double, being double: longing, belonging, recognition, and evasion in psychodynamic work with immigrants.

PubMed

Boulanger, Ghislaine

2015-09-01

Psychically immigrants live double lives, simultaneously dwelling in the world they have left and the world in which they live, and into which most try to fit to avoid the alienating experience of being "other". Doubleness is not a conscious act, but it is a preconscious counterpoint to just about every social interaction. I argue that successful psychodynamic treatment allows immigrants to take the doubleness for granted, in effect seeing double and being double. In this way they come to effortlessly privilege one self-state over the other. The recognition and acceptance of competing self-states proves transformative in any treatment, but never more so than in working with immigrants who contend with several culturally competing selves in their daily lives and seek one relationship in which they can all be seen and heard. I describe treating an immigrant who, when I began to work with her, excelled at seeing double, but being double posed a terrifying dilemma. At least two self-states were engaged in a tug of war; she feared that the winner would take all.

Biodegradable double-targeted PTX-mPEG-PLGA nanoparticles for ultrasound contrast enhanced imaging and antitumor therapy in vitro.

PubMed

Ma, Jing; Shen, Ming; Xu, Chang Song; Sun, Ying; Duan, You Rong; Du, Lian Fang

2016-11-29

A porous-structure nano-scale ultrasound contrast agent (UCA) was made of monomethoxypoly (ethylene glycol)-poly (lactic-co-glycolic acid) (mPEG-PLGA), and modified by double-targeted antibody: anti-carcinoembryonic antigen (CEA) and anti-carbohydrate antigen 19-9 (CA19-9), as a double-targeted nanoparticles (NPs). Anti-tumor drug paclitaxel (PTX) was encapsulated in the double-targeted nanoparticles (NPs). The morphor and release curve were characterized. We verified a certain anticancer effect of PTX-NPs through cytotoxicity experiments. The cell uptake result showed much more NPs may be facilitated to ingress the cells or tissues with ultrasound (US) or ultrasound targeted microbubble destruction (UTMD) transient sonoporation in vitro. Ultrasound contrast-enhanced images in vitro and in vivo were investigated. Compared with SonoVue, the NPs prolonged imaging time in rabbit kidneys and tumor of nude mice, which make it possible to further enhance anti-tumor effects by extending retention time in the tumor region. The novel double-targeted NPs with the function of ultrasound contrast enhanced imaging and anti-tumor therapy can be a promising way in clinic.

DEVELOPMENTAL TOXICITY OF 2-CHLORO-2'-DEOXYADENOSINE IN THE RAT: INDUCTION OF LUMBAR HERNIA

EPA Science Inventory

DEVELOPMENTAL TOXICITY OF 2-CHLORO-2'DEOXYADENOSINE IN THE RAT: INDUCTION OF LUMBAR HERNIA. C. Lau1, M.G. Narotsky1, D. Lui1, D. Best1, R.W. Setzer2, T.B. Knudsen3. 1Reprod. Tox. Div., 2Exp. Tox. Div., NHEERL, US EPA, Research Triangle Park, NC, USA, 3Dept. Path. Anat. Cell Bio...

Synthesis, Biological Evaluation, and Structure–Activity Relationships of Novel Substituted N-Phenyl Ureidobenzenesulfonate Derivatives Blocking Cell Cycle Progression in S-Phase and Inducing DNA Double-Strand Breaks

PubMed Central

2012-01-01

Twenty-eight new substituted N-phenyl ureidobenzenesulfonate (PUB-SO) and 18 N-phenylureidobenzenesulfonamide (PUB-SA) derivatives were prepared. Several PUB-SOs exhibited antiproliferative activity at the micromolar level against the HT-29, M21, and MCF-7 cell lines and blocked cell cycle progression in S-phase similarly to cisplatin. In addition, PUB-SOs induced histone H2AX (γH2AX) phosphorylation, indicating that these molecules induce DNA double-strand breaks. In contrast, PUB-SAs were less active than PUB-SOs and did not block cell cycle progression in S-phase. Finally, PUB-SOs 4 and 46 exhibited potent antitumor activity in HT-1080 fibrosarcoma cells grafted onto chick chorioallantoic membranes, which was similar to cisplatin and combretastatin A-4 and without significant toxicity toward chick embryos. These new compounds are members of a promising new class of anticancer agents. PMID:22694057

Double-strand break repair-adox: Restoration of suppressed double-strand break repair during mitosis induces genomic instability.

PubMed

Terasawa, Masahiro; Shinohara, Akira; Shinohara, Miki

2014-12-01

Double-strand breaks (DSBs) are one of the severest types of DNA damage. Unrepaired DSBs easily induce cell death and chromosome aberrations. To maintain genomic stability, cells have checkpoint and DSB repair systems to respond to DNA damage throughout most of the cell cycle. The failure of this process often results in apoptosis or genomic instability, such as aneuploidy, deletion, or translocation. Therefore, DSB repair is essential for maintenance of genomic stability. During mitosis, however, cells seem to suppress the DNA damage response and proceed to the next G1 phase, even if there are unrepaired DSBs. The biological significance of this suppression is not known. In this review, we summarize recent studies of mitotic DSB repair and discuss the mechanisms of suppression of DSB repair during mitosis. DSB repair, which maintains genomic integrity in other phases of the cell cycle, is rather toxic to cells during mitosis, often resulting in chromosome missegregation and aberration. Cells have multiple safeguards to prevent genomic instability during mitosis: inhibition of 53BP1 or BRCA1 localization to DSB sites, which is important to promote non-homologous end joining or homologous recombination, respectively, and also modulation of the non-homologous end joining core complex to inhibit DSB repair. We discuss how DSBs during mitosis are toxic and the multiple safeguard systems that suppress genomic instability. © 2014 The Authors. Cancer Science published by Wiley Publishing Asia Pty Ltd on behalf of Japanese Cancer Association.

Evaporation Study of an Ionic Liquid with a Double-Charged Cation.

PubMed

Chilingarov, Norbert S; Zhirov, Maksim S; Shmykova, Anna M; Martynova, Ekaterina A; Glukhov, Lev M; Chernikova, Elena A; Kustov, Leonid M; Markov, Vitaliy Yu; Ioutsi, Vitaliy A; Sidorov, Lev N

2018-05-07

The evaporation of a dicationic ionic liquid, 1,3-bis(3-methylimidazolium-1-yl)propane bis(trifluoromethanesulfonyl)amide ([C 3 (MIm) 2 2+ ][Tf 2 N - ] 2 ), was studied by Knudsen effusion mass spectrometry. Its evaporation is accompanied by a partial thermal decomposition producing monocationic ionic liquids, 1,3-dimethylimidazolium and 1-(2-propenyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)amides, as volatile products. This decomposition does not affect the vaporization characteristics of [C 3 (MIm) 2 2+ ][Tf 2 N - ] 2 , which were established to be as follows. The vaporization enthalpy (550 K) is equal to (155.5 ± 3.2) kJ·mol -1 ; the saturated vapor pressure is described by the equation ln( p/Pa) = -(18699 ± 381)/( T/K) + (30.21 ± 0.82) in the range of 508-583 K. 1,3-Bis(3-methylimidazolium-1-yl)propane bis(trifluoromethanesulfonyl)amide is the first dicationic ionic liquid, the vaporization characteristics of which were determined with an acceptable accuracy.

Linearity Can Account for the Similarity Among Conventional, Frequency-Doubling, and Gabor-Based Perimetric Tests in the Glaucomatous Macula

PubMed Central

DUL, MITCHELL W.; SWANSON, WILLIAM H.

2006-01-01

Purposes The purposes of this study are to compare macular perimetric sensitivities for conventional size III, frequency-doubling, and Gabor stimuli in terms of Weber contrast and to provide a theoretical interpretation of the results. Methods Twenty-two patients with glaucoma performed four perimetric tests: a conventional Swedish Interactive Threshold Algorithm (SITA) 10-2 test with Goldmann size III stimuli, two frequency-doubling tests (FDT 10-2, FDT Macula) with counterphase-modulated grating stimuli, and a laboratory-designed test with Gabor stimuli. Perimetric sensitivities were converted to the reciprocal of Weber contrast and sensitivities from different tests were compared using the Bland-Altman method. Effects of ganglion cell loss on perimetric sensitivities were then simulated with a two-stage neural model. Results The average perimetric loss was similar for all stimuli until advanced stages of ganglion cell loss, in which perimetric loss tended to be greater for size III stimuli than for frequency-doubling and Gabor stimuli. Comparison of the experimental data and model simulation suggests that, in the macula, linear relations between ganglion cell loss and perimetric sensitivity loss hold for all three stimuli. Conclusions Linear relations between perimetric loss and ganglion cell loss for all three stimuli can account for the similarity in perimetric loss until advanced stages. The results do not support the hypothesis that redundancy for frequency-doubling stimuli is lower than redundancy for size III stimuli. PMID:16840860

hMSH5 Facilitates the Repair of Camptothecin-induced Double-strand Breaks through an Interaction with FANCJ*

PubMed Central

Xu, Yang; Wu, Xiling; Her, Chengtao

2015-01-01

Replication stress from stalled or collapsed replication forks is a major challenge to genomic integrity. The anticancer agent camptothecin (CPT) is a DNA topoisomerase I inhibitor that causes fork collapse and double-strand breaks amid DNA replication. Here we report that hMSH5 promotes cell survival in response to CPT-induced DNA damage. Cells deficient in hMSH5 show elevated CPT-induced γ-H2AX and RPA2 foci with concomitant reduction of Rad51 foci, indicative of impaired homologous recombination. In addition, CPT-treated hMSH5-deficient cells exhibit aberrant activation of Chk1 and Chk2 kinases and therefore abnormal cell cycle progression. Furthermore, the hMSH5-FANCJ chromatin recruitment underlies the effects of hMSH5 on homologous recombination and Chk1 activation. Intriguingly, FANCJ depletion desensitizes hMSH5-deficient cells to CPT-elicited cell killing. Collectively, our data point to the existence of a functional interplay between hMSH5 and FANCJ in double-strand break repair induced by replication stress. PMID:26055704

How do culture media influence in vitro perivascular cell behavior?

PubMed

Huber, Birgit; Volz, Ann-Cathrin; Kluger, Petra Juliane

2015-12-01

Perivascular cells are multilineage cells located around the vessel wall and important for wall stabilization. In this study, we evaluated a stem cell media and a perivascular cell-specific media for the culture of primary perivascular cells regarding their cell morphology, doubling time, stem cell properties, and expression of cell type-specific markers. When the two cell culture media were compared to each other, perivascular cells cultured in the stem cell medium had a more elongated morphology and a faster doubling rate and cells cultured in the pericyte medium had a more typical morphology, with several filopodia, and a slower doubling rate. To evaluate stem cell properties, perivascular cells, CD146(-) cells, and mesenchymal stem cells (MSCs) were differentiated into the adipogenic, osteogenic, and chondrogenic lineages. It was seen that perivascular cells, as well as CD146(-) cells and MSCs, cultured in stem cell medium showed greater differentiation than cells cultured in pericyte-specific medium. The expression of pericyte-specific markers CD146, neural/glial antigen 2 (NG2), platelet-derived growth factor receptor-β (PDGFR-β), myosin, and α-smooth muscle actin (α-SMA) could be found in both pericyte cultures, as well as to varying amounts in CD146(-) cells, MSCs, and endothelial cells. The here presented work shows that perivascular cells can adapt to their in vitro environment and cell culture conditions influence cell functionality, such as doubling rate or differentiation behavior. Pericyte-specific markers were shown to be expressed also from cells other than perivascular cells. We can further conclude that CD146(+) perivascular cells are inhomogeneous cell population probably containing stem cell subpopulations, which are located perivascular around capillaries. © 2015 International Federation for Cell Biology.

Phenolic promiscuity in the cell nucleus--epigallocatechingallate (EGCG) and theaflavin-3,3'-digallate from green and black tea bind to model cell nuclear structures including histone proteins, double stranded DNA and telomeric quadruplex DNA.

PubMed

Mikutis, Gediminas; Karaköse, Hande; Jaiswal, Rakesh; LeGresley, Adam; Islam, Tuhidul; Fernandez-Lahore, Marcelo; Kuhnert, Nikolai

2013-02-01

Flavanols from tea have been reported to accumulate in the cell nucleus in considerable concentrations. The nature of this phenomenon, which could provide novel approaches in understanding the well-known beneficial health effects of tea phenols, is investigated in this contribution. The interaction between epigallocatechin gallate (EGCG) from green tea and a selection of theaflavins from black tea with selected cell nuclear structures such as model histone proteins, double stranded DNA and quadruplex DNA was investigated using mass spectrometry, Circular Dichroism spectroscopy and fluorescent assays. The selected polyphenols were shown to display affinity to all of the selected cell nuclear structures, thereby demonstrating a degree of unexpected molecular promiscuity. Most interestingly theaflavin-digallate was shown to display the highest affinity to quadruplex DNA reported for any naturally occurring molecule reported so far. This finding has immediate implications in rationalising the chemopreventive effect of the tea beverage against cancer and possibly the role of tea phenolics as "life span essentials".

Comparison of the induction and disappearance of DNA double strand breaks and gamma-H2AX foci after irradiation of chromosomes in G1-phase or in condensed metaphase cells.

PubMed

Kato, Takamitsu A; Okayasu, Ryuichi; Bedford, Joel S

2008-03-01

The induction and disappearance of DNA double strand breaks (DSBs) after irradiation of G1 and mitotic cells were compared with the gamma-H2AX foci assay and a gel electrophoresis assay. This is to determine whether cell cycle related changes in chromatin structure might influence the gamma-H2AX assay which depends on extensive phosphorylation and dephosphorylation of the H2AX histone variant surrounding DSBs. The disappearance of gamma-H2AX foci after irradiation was much slower for mitotic than for G1 cells. On the other hand, no difference was seen for the gel electrophoresis assay. Our data may suggest the limited accessibility of dephosphorylation enzyme in irradiated metaphase cells or trapped gamma-H2AX in condensed chromatin.

Y-configuration double-stent-assisted coiling using two closed-cell stents for wide-neck basilar tip aneurysms.

PubMed

Jeon, Pyoung; Kim, Byung Moon; Kim, Dong Joon; Kim, Dong I K; Park, Keun Young

2014-09-01

This study aimed to evaluate clinical and angiographic outcomes of Y-configuration double-stent-assisted (Y-stent) coiling using two closed-cell stents for wide-necked basilar tip aneurysm (BTA). A total of 25 patients underwent Y-stent coiling using two closed-cell stents as a first-time treatment in 18 (3 ruptured) BTAs, retreatment in 2 BTAs and as a third treatment in 5 wide-necked BTAs. Clinical and angiographic outcomes were evaluated retrospectively. Treatment-related complications were three (12.0 %) thromboembolic infarctions due to two acute in-stent thromboses and one embolism. Twenty-two (88 %) patients had favorable outcomes (modified Rankin scale score [mRS], 0-2) during the follow-up period (mean, 30 months; range, 6-54 months). Two patients died: one from initial subarachnoid hemorrhage and the other from intracerebral hemorrhage due to underlying Moyamoya disease. Post-treatment angiograms showed complete occlusion in nine aneurysms, residual neck in 11 aneurysms and residual sac in five aneurysms. Follow-up angiograms were available at least once between 5 to 34 months (mean, 16 months) in 21 patients. Nineteen patients showed improved or stable states (complete occlusion, n = 17; residual neck, n = 2). Major recurrences occurred in two BTAs (9.5 %). Those two major recurrent aneurysms had been large-sized aneurysms at the initial coiling procedure. Both showed not only coil compaction but also progressive growth to giant-sized aneurysms and intra-aneurysmal thrombus formation at the Y-stent coiling as a third-time treatment. Y-stent coiling using two closed-cell stents is a safe and durable treatment option for wide-necked BTA, but may have limited efficacy for large/giant sized and thrombosed aneurysms.

The Design and its Verification of the Double Rotor Double Cage Induction Motor

NASA Astrophysics Data System (ADS)

Sinha, Sumita; Deb, Nirmal K.; Biswas, Sujit K.

2017-02-01

The concept of a double rotor motor presented earlier and its equivalent circuit has been developed, showing a non-linear parameter content. The two rotors (which are recommended to be double cage type for development of high starting torque) can run with equal or unequal speed independently, depending on their individual loading. This paper presents the elaborate design procedure, step-by-step, for the double rotor double cage motor and verifies the designed data with that obtained from three separate tests (compared to two for conventional motor) on a prototype, such that optimum performance can be obtained from the motor.

Hyaluronic acid enhances the effect of the PAMPS/PDMAAm double-network hydrogel on chondrogenic differentiation of ATDC5 cells

PubMed Central

2014-01-01

Background A double-network (DN) gel, which was composed of poly-(2-Acrylamido-2-methylpropanesulfonic acid) and poly-(N,N’-dimethyl acrylamide) (PAMPS/PDMAAm), has the potential to induce chondrogenesis both in vitro and in vivo. The present study investigated whether DN gel induced chondrogenic differentiation of ATDC5 cells in a maintenance medium without insulin, and whether supplementation of hyaluronic acid enhanced the chondrogenic differentiation effect of DN gel. Methods ATDC5 cells were cultured on the DN gel and the polystyrene (PS) dish in maintenance media without insulin for 21 days. Hyaluronic acid having a molecular weight of approximately 800 kDa was supplemented into the medium so that the concentration became 0.01, 0.1, or 1.0 mg/mL. The cultured cells were evaluated using immunocytochemistry for type-2 collagen and real time PCR for gene expression of type-2 collagen, aggrecan, and Sox9 at 7 and 21 days of culture. Results The cells cultured on the DN gel formed nodules and were stained with an anti-type-2 collagen antibody, and expression of type-2 collagen and aggrecan mRNA was significantly greater on the DN gel than on the PS dish surface (p < 0.05) in the hyaluronic acid-free maintenance medium. Hyaluronic acid supplementation of a high concentration (1.0 mg/mL) significantly enhanced expression of type-2 collagen and aggrecan mRNA in comparison with culture without hyaluronic acid at 21 days (p < 0.05). Conclusions The DN gel induced chondrogenic differentiation of ATDC5 cells without insulin. This effect was significantly affected by hyaluronic acid, depending on the level of concentration. There is a high possibility that hyaluronic acid plays an important role in the in vivo hyaline cartilage regeneration phenomenon induced by the DN gel. PMID:24997593

Hyaluronic acid enhances the effect of the PAMPS/PDMAAm double-network hydrogel on chondrogenic differentiation of ATDC5 cells.

PubMed

Kitamura, Nobuto; Kurokawa, Takayuki; Fukui, Takaaki; Gong, Jian P; Yasuda, Kazunori

2014-07-06

A double-network (DN) gel, which was composed of poly-(2-Acrylamido-2-methylpropanesulfonic acid) and poly-(N,N'-dimethyl acrylamide) (PAMPS/PDMAAm), has the potential to induce chondrogenesis both in vitro and in vivo. The present study investigated whether DN gel induced chondrogenic differentiation of ATDC5 cells in a maintenance medium without insulin, and whether supplementation of hyaluronic acid enhanced the chondrogenic differentiation effect of DN gel. ATDC5 cells were cultured on the DN gel and the polystyrene (PS) dish in maintenance media without insulin for 21 days. Hyaluronic acid having a molecular weight of approximately 800 kDa was supplemented into the medium so that the concentration became 0.01, 0.1, or 1.0 mg/mL. The cultured cells were evaluated using immunocytochemistry for type-2 collagen and real time PCR for gene expression of type-2 collagen, aggrecan, and Sox9 at 7 and 21 days of culture. The cells cultured on the DN gel formed nodules and were stained with an anti-type-2 collagen antibody, and expression of type-2 collagen and aggrecan mRNA was significantly greater on the DN gel than on the PS dish surface (p < 0.05) in the hyaluronic acid-free maintenance medium. Hyaluronic acid supplementation of a high concentration (1.0 mg/mL) significantly enhanced expression of type-2 collagen and aggrecan mRNA in comparison with culture without hyaluronic acid at 21 days (p < 0.05). The DN gel induced chondrogenic differentiation of ATDC5 cells without insulin. This effect was significantly affected by hyaluronic acid, depending on the level of concentration. There is a high possibility that hyaluronic acid plays an important role in the in vivo hyaline cartilage regeneration phenomenon induced by the DN gel.

Synthetic transcripts of double-stranded Birnavirus genome are infectious.

PubMed Central

Mundt, E; Vakharia, V N

1996-01-01

We have developed a system for generation of infectious bursal disease virus (IBDV), a segmented double-stranded RNA virus of the Birnaviridae family, with the use of synthetic transcripts derived from cloned cDNA. Independent full-length cDNA clones were constructed that contained the entire coding and noncoding regions of RNA segments A and B of two distinguishable IBDV strains of serotype I. Segment A encodes all of the structural (VP2, VP4, and VP3) and nonstructural (VP5) proteins, whereas segment B encodes the RNA-dependent RNA polymerase (VP1). Synthetic RNAs of both segments were produced by in vitro transcription of linearized plasmids with T7 RNA polymerase. Transfection of Vero cells with combined plus-sense transcripts of both segments generated infectious virus as early as 36 hr after transfection. The infectivity and specificity of the recovered chimeric virus was ascertained by the appearance of cytopathic effect in chicken embryo cells, by immunofluorescence staining of infected Vero cells with rabbit anti-IBDV serum, and by nucleotide sequence analysis of the recovered virus, respectively. In addition, transfectant viruses containing genetically tagged sequences in either segment A or segment B of IBDV were generated to confirm the feasibility of this system. The development of a reverse genetics system for double-stranded RNA viruses will greatly facilitate studies of the regulation of viral gene expression, pathogenesis, and design of a new generation of live vaccines. Images Fig. 2 Fig. 3 Fig. 4 PMID:8855321

Regulatory role of NKG2D+ NK cells in intestinal lamina propria by secreting double-edged Th1 cytokines in ulcerative colitis

PubMed Central

Lin, Xue; Chang, Ying; Liu, Jing; Zhou, Rui; Nie, Jia-Yan; Dong, Wei-Guo; Zhao, Qiu; Li, Jin

2017-01-01

The role of intestinal lamina propria (LP) NKG2D+ NK cells is unclear in regulating Th1/Th2 balance in ulcerative colitis (UC). In this study, we investigated the frequency of LP NKG2D+ NK cells in DSS-induced colitis model and intestinal mucosal samples of UC patients, as well as the secretion of Th1/Th2/Th17 cytokines in NK cell lines after MICA stimulation. The role of Th1 cytokines in UC was validated by bioinformatics analysis. We found that DSS-induced colitis in mice was characterized by a Th2-mediated process. In acute phrase, the frequency of LP NKG2D+ lymphocytes increased significantly and decreased in remission, while the frequency of LP NKG2D+ NK cells decreased significantly in acute phase and increased in remission. No obvious change was found in the frequency of total LP NK cells. Similarly, severe UC patients had a higher expression of mucosal NKG2D and a lower number of NKG2D+ NK cells than mild to moderate UC. In NK cell lines, the MICA stimulation could induce a predominant secretion of Th1 cytokines (TNF, IFN-γ). Furthermore, in bioinformatics analysis, mucosal Th1 cytokine of TNF, showed a double-edged role in UC when compared to the Th1-mediated disease of Crohn's colitis. In conclusion, LP NKG2D+ NK cells partially played a regulatory role in UC through secreting Th1 cytokines to regulate the Th2-predominant Th1/Th2 imbalance, despite of the concomitant pro-inflammatory effects of Th1 cytokines. PMID:29228739

Moist, Double-diffusive convection

NASA Astrophysics Data System (ADS)

Oishi, Jeffrey; Burns, Keaton; Brown, Ben; Lecoanet, Daniel; Vasil, Geoffrey

2017-11-01

Double-diffusive convection occurs when the competition between stabilizing and a destabilizing buoyancy source is mediated by a difference in the diffusivity of each source. Such convection is important in a wide variety of astrophysical and geophysical flows. However, in giant planets, double-diffusive convection occurs in regions where condensation of important components of the atmosphere occurs. Here, we present preliminary calculations of moist, double-diffusive convection using the Dedalus pseudospectral framework. Using a simple model for phase change, we verify growth rates for moist double diffusive convection from linear calculations and report on preliminary relationships between the ability to form liquid phase and the resulting Nusselt number in nonlinear simulations.

Ingestion of bacterially expressed double-stranded RNA inhibits gene expression in planarians.

PubMed

Newmark, Phillip A; Reddien, Peter W; Cebrià, Francesc; Sánchez Alvarado, Alejandro

2003-09-30

Freshwater planarian flatworms are capable of regenerating complete organisms from tiny fragments of their bodies; the basis for this regenerative prowess is an experimentally accessible stem cell population that is present in the adult planarian. The study of these organisms, classic experimental models for investigating metazoan regeneration, has been revitalized by the application of modern molecular biological approaches. The identification of thousands of unique planarian ESTs, coupled with large-scale whole-mount in situ hybridization screens, and the ability to inhibit planarian gene expression through double-stranded RNA-mediated genetic interference, provide a wealth of tools for studying the molecular mechanisms that regulate tissue regeneration and stem cell biology in these organisms. Here we show that, as in Caenorhabditis elegans, ingestion of bacterially expressed double-stranded RNA can inhibit gene expression in planarians. This inhibition persists throughout the process of regeneration, allowing phenotypes with disrupted regenerative patterning to be identified. These results pave the way for large-scale screens for genes involved in regenerative processes.

Hematopoietic Stem Cells from Ts65Dn Mice Are Deficient in the Repair of DNA Double-Strand Breaks.

PubMed

Wang, Yingying; Chang, Jianhui; Shao, Lijian; Feng, Wei; Luo, Yi; Chow, Marie; Du, Wei; Meng, Aimin; Zhou, Daohong

2016-06-01

Down syndrome (DS) is a genetic disorder caused by the presence of an extra partial or whole copy of chromosome 21. In addition to musculoskeletal and neurodevelopmental abnormalities, children with DS exhibit various hematologic disorders and have an increased risk of developing acute lymphoblastic leukemia and acute megakaryocytic leukemia. Using the Ts65Dn mouse model, we investigated bone marrow defects caused by trisomy for 132 orthologs of the genes on human chromosome 21. The results showed that, although the total bone marrow cellularity as well as the frequency of hematopoietic progenitor cells (HPCs) was comparable between Ts65Dn mice and their age-matched euploid wild-type (WT) control littermates, human chromosome 21 trisomy led to a significant reduction in hematopoietic stem cell (HSC) numbers and clonogenic function in Ts65Dn mice. We also found that spontaneous DNA double-strand breaks (DSBs) were significantly increased in HSCs from the Ts65Dn mice, which was correlated with the significant reduction in HSC clonogenic activity compared to those from WT controls. Moreover, analysis of the repair kinetics of radiation-induced DSBs revealed that HSCs from Ts65Dn mice were less proficient in DSB repair than the cells from WT controls. This deficiency was associated with a higher sensitivity of Ts65Dn HSCs to radiation-induced suppression of HSC clonogenic activity than that of euploid HSCs. These findings suggest that an additional copy of genes on human chromosome 21 may selectively impair the ability of HSCs to repair DSBs, which may contribute to DS-associated hematological abnormalities and malignancies.

Hematopoietic Stem Cells from Ts65Dn Mice Are Deficient in the Repair of DNA Double-Strand Breaks

PubMed Central

Wang, Yingying; Chang, Jianhui; Shao, Lijian; Feng, Wei; Luo, Yi; Chow, Marie; Du, Wei; Meng, Aimin; Zhou, Daohong

2016-01-01

Down syndrome (DS) is a genetic disorder caused by the presence of an extra partial or whole copy of chromosome 21. In addition to musculoskeletal and neurodevelopmental abnormalities, children with DS exhibit various hematologic disorders and have an increased risk of developing acute lymphoblastic leukemia and acute megakaryocytic leukemia. Using the Ts65Dn mouse model, we investigated bone marrow defects caused by trisomy for 132 orthologs of the genes on human chromosome 21. The results showed that, although the total bone marrow cellularity as well as the frequency of hematopoietic progenitor cells (HPCs) was comparable between Ts65Dn mice and their age-matched euploid wild-type (WT) control littermates, human chromosome 21 trisomy led to a significant reduction in hematopoietic stem cell (HSC) numbers and clonogenic function in Ts65Dn mice. We also found that spontaneous DNA double-strand breaks (DSBs) were significantly increased in HSCs from the Ts65Dn mice, which was correlated with the significant reduction in HSC clonogenic activity compared to those from WT controls. Moreover, analysis of the repair kinetics of radiation-induced DSBs revealed that HSCs from Ts65Dn mice were less proficient in DSB repair than the cells from WT controls. This deficiency was associated with a higher sensitivity of Ts65Dn HSCs to radiation-induced suppression of HSC clonogenic activity than that of euploid HSCs. These findings suggest that an additional copy of genes on human chromosome 21 may selectively impair the ability of HSCs to repair DSBs, which may contribute to DS-associated hematological abnormalities and malignancies. PMID:27243896

Immune mechanism: a 'double-edged sword'.

PubMed

Musa, Mustaffa

2013-05-01

Immunology has now developed into an independent discipline in medicine which covers not only germ infection which is related to immunity solely but also covers a lot of non-infectious diseases such as autoimmune disease, allergies, and others. Therefore, "The Immune Mechanism: "A Double-Edged Sword" means that the immune mechanism (consisted of antibody mediated mechanism and T cell mediated mechanism), just like one edge playing the role of giving benefit (immunity) as it destroys the agent of infection, and another one can be detrimental as it will cause tissue/cell damages and then give rise to immune diseases (immunopathology). Now, the prevalence of these immune diseases is on the rise and has become a new challenge to our country towards developed country in 2020. Therefore, we have to make ample preparation (laboratory facilities/services, main power, and research) from now on in order to face the problems and challenges.

Peripheral territory and neuropeptides of the trigeminal ganglion neurons centrally projecting through the oculomotor nerve demonstrated by fluorescent retrograde double-labeling combined with immunocytochemistry.

PubMed

Bortolami, R; Calzà, L; Lucchi, M L; Giardino, L; Callegari, E; Manni, E; Pettorossi, V E; Barazzoni, A M; Lalatta Costerbosa, G

1991-04-26

The peripheral territories of sheep trigeminal neurons which send their central process to the brainstem through the oculomotor nerve were investigated by the use of fluorescent tracers in double-labeling experiments. For this purpose Diamidino yellow (DY) injection into the oculomotor nerve was combined with Fast blue (FB) injection either into the extraocular muscles (EOMs), or the cornea, or the superior eyelid. Double-labeled DY + FB cells were found in the ophthalmic region of the trigeminal ganglion in addition to single-labeled DY or FB cells. The DY and DY + FB-labeled trigeminal cells were analysed immunocytochemically for their content of substance P (SP)-, calcitonin gene-related peptide (CGRP)-, and cholecystokinin-8 (CCK-8)-like. All single-labeled DY cells showed SP-, CGRP- or CCK-8-like immunoreactivity. Double-labeled DY + FB neurons innervating the EOMs were immunoreactive for each of the three peptides, whereas double-labeled neurons supplying the cornea were only CGRP-like positive. The findings suggest that, in the sheep, trigeminal neurons which send their process centrally through the oculomotor nerve supply the EOMs, the cornea, and the superior eyelid and contain neuropeptides which are usually associated with pain sensation.

Synthesis, characterization, and efficacy of antituberculosis isoniazid zinc aluminum-layered double hydroxide based nanocomposites

PubMed Central

Saifullah, Bullo; El Zowalaty, Mohamed Ezzat; Arulselvan, Palanisamy; Fakurazi, Sharida; Webster, Thomas J; Geilich, Benjamin Mahler; Hussein, Mohd Zobir

2016-01-01

The chemotherapy for tuberculosis (TB) is complicated by its long-term treatment, its frequent drug dosing, and the adverse effects of anti-TB drugs. In this study, we have developed two nanocomposites (A and B) by intercalating the anti-TB drug isoniazid (INH) into Zn/Al-layered double hydroxides. The average size of the nanocomposites was found to bê164 nm. The efficacy of the Zn/Al-layered double hydroxides intercalated INH against Mycobacterium tuberculosis was increased by approximately three times more than free INH. The nanocomposites were also found to be active against Gram-positive and -negative bacteria. Compared to the free INH, the nanodelivery formulation was determined to be three times more biocompatible with human normal lung fibroblast MRC-5 cells and 3T3 fibroblast cells at a very high concentration of 50 µg/mL for up to 72 hours. The in vitro release of INH from the Zn/Al-layered double hydroxides was found to be sustained in human body-simulated buffer solutions of pH 4.8 and 7.4. This research is a step forward in making the TB chemotherapy patient friendly. PMID:27486322

Tumor-treating fields elicit a conditional vulnerability to ionizing radiation via the downregulation of BRCA1 signaling and reduced DNA double-strand break repair capacity in non-small cell lung cancer cell lines.

PubMed

Karanam, Narasimha Kumar; Srinivasan, Kalayarasan; Ding, Lianghao; Sishc, Brock; Saha, Debabrata; Story, Michael D

2017-03-30

The use of tumor-treating fields (TTFields) has revolutionized the treatment of recurrent and newly diagnosed glioblastoma (GBM). TTFields are low-intensity, intermediate frequency, alternating electric fields that are applied to tumor regions and cells using non-invasive arrays. The predominant mechanism by which TTFields are thought to kill tumor cells is the disruption of mitosis. Using five non-small cell lung cancer (NSCLC) cell lines we found that there is a variable response in cell proliferation and cell killing between these NSCLC cell lines that was independent of p53 status. TTFields treatment increased the G2/M population, with a concomitant reduction in S-phase cells followed by the appearance of a sub-G1 population indicative of apoptosis. Temporal changes in gene expression during TTFields exposure was evaluated to identify molecular signaling changes underlying the differential TTFields response. The most differentially expressed genes were associated with the cell cycle and cell proliferation pathways. However, the expression of genes found within the BRCA1 DNA-damage response were significantly downregulated (P<0.05) during TTFields treatment. DNA double-strand break (DSB) repair foci increased when cells were exposed to TTFields as did the appearance of chromatid-type aberrations, suggesting an interphase mechanism responsible for cell death involving DNA repair. Exposing cells to TTFields immediately following ionizing radiation resulted in increased chromatid aberrations and a reduced capacity to repair DNA DSBs, which were likely responsible for at least a portion of the enhanced cell killing seen with the combination. These findings suggest that TTFields induce a state of 'BRCAness' leading to a conditional susceptibility resulting in enhanced sensitivity to ionizing radiation and provides a strong rationale for the use of TTFields as a combined modality therapy with radiation or other DNA-damaging agents.

Double layers and circuits in astrophysics

NASA Technical Reports Server (NTRS)

Alfven, Hannes

1986-01-01

As the rate of energy release in a double layer with voltage delta V is P approx I delta V, a double layer must be treated as a part of a circuit which delivers the current I. As neither double layer nor circuit can be derived from magnetofluid models of a plasma, such models are useless for treating energy transfer by means of double layers. They must be replaced by particle models and circuit theory. A simple circuit is suggested which is applied to the energizing of auroral particles, to solar flares, and to intergalactic double radio sources. Application to the heliospheric current systems leads to the prediction of two double layers on the Sun's axis which may give radiations detectable from Earth. Double layers in space should be classified as a new type of celestial object (one example is the double radio sources). It is tentatively suggested in X-ray and Gamma-ray bursts may be due to exploding double layers (although annihilation is an alternative energy source). A study of how a number of the most used textbooks in astrophysics treat important concepts like double layers, critical velocity, pinch effects and circuits is made.

Simulation of double stage hall thruster with double-peaked magnetic field

NASA Astrophysics Data System (ADS)

Ding, Yongjie; Li, Peng; Sun, Hezhi; Wei, Liqiu; Xu, Yu; Peng, Wuji; Su, Hongbo; Li, Hong; Yu, Daren

2017-07-01

This study adopts double permanent magnetic rings and four permanent magnetic rings to form two symmetrical magnetic peaks and two asymmetrical magnetic peaks in the channel of a Hall thruster, and uses a 2D-3V PIC-MCC model to analyze the influence of magnetic strength on the discharge characteristic and performance of Hall thrusters with an intermediate electrode and double-peaked magnetic field. As opposed to the two symmetrical magnetic peaks formed by double permanent magnetic rings, increasing the magnetic peak value deep within the channel can cause propellant ionization to occur; with the increase in the magnetic peak deep in the channel, the propellant utilization, thrust, and anode efficiency of the thruster are significantly improved. Double-peaked magnetic field can realize separate control of ionization and acceleration in a Hall thruster, and provide technical means for further improving thruster performance. Contribution to the Topical Issue "Physics of Ion Beam Sources", edited by Holger Kersten and Horst Neumann.

Double reading.

PubMed

Kopans, D B

2000-07-01

Clearly, the cost of double reading varies with the approach used. The Massachusetts General Hospital method can only lead to an increase in recalls and the costs that these engender (anxiety for the women recalled, trauma from any biopsies obtained, and the actual monetary costs of additional imaging and interventions). It is of interest that one potential cost, the concern that women recalled may be reluctant to participate again in screening, does not seem to be the case. Women who are recalled appear to be more likely to participate in future screening. Double interpretation where there must be a consensus between the interpreting radiologists, and if this cannot be reached a third arbiter, is the most labor intensive, but can reduce the number of recalls in a double reading system. Computer systems have been developed to act as a second reader. The films must be digitized and then fed through the reader, but studies suggest that the computer can identify cancers that may be overlooked by a human reader. The challenge is to do this without too many false-positive calls. If the radiologist finds the false-positives are too numerous and distracting, then the system is not used. As digital mammographic systems proliferate, and computer algorithms become more sophisticated, the second human reader will likely be replaced by a computer-aided detection system and double reading will become the norm.

Specific inhibition of gene expression by small double-stranded RNAs in invertebrate and vertebrate systems

PubMed Central

Caplen, Natasha J.; Parrish, Susan; Imani, Farhad; Fire, Andrew; Morgan, Richard A.

2001-01-01

Short interfering RNAs (siRNAs) are double-stranded RNAs of ≈21–25 nucleotides that have been shown to function as key intermediaries in triggering sequence-specific RNA degradation during posttranscriptional gene silencing in plants and RNA interference in invertebrates. siRNAs have a characteristic structure, with 5′-phosphate/3′-hydroxyl ends and a 2-base 3′ overhang on each strand of the duplex. In this study, we present data that synthetic siRNAs can induce gene-specific inhibition of expression in Caenorhabditis elegans and in cell lines from humans and mice. In each case, the interference by siRNAs was superior to the inhibition of gene expression mediated by single-stranded antisense oligonucleotides. The siRNAs seem to avoid the well documented nonspecific effects triggered by longer double-stranded RNAs in mammalian cells. These observations may open a path toward the use of siRNAs as a reverse genetic and therapeutic tool in mammalian cells. PMID:11481446

A facile electrode preparation method for accurate electrochemical measurements of double-side-coated electrode from commercial Li-ion batteries

NASA Astrophysics Data System (ADS)

Zhou, Ge; Wang, Qiyu; Wang, Shuo; Ling, Shigang; Zheng, Jieyun; Yu, Xiqian; Li, Hong

2018-04-01

The post mortem electrochemical analysis, including charge-discharge and electrochemical impedance spectroscopy (EIS) measurements, are critical steps for revealing the failure mechanisms of commercial lithium-ion batteries (LIBs). These post measurements usually require the reassembling of coin-cell with electrode which is often double-side-coated in commercial LIBs. It is difficult to use such double-side-coated electrode to perform accurate electrochemical measurements because the back side of the electrode is coated with active materials, rather than single-side-coated electrode that is often used in coin-cell measurements. In this study, we report a facile tape-covering sample preparation method, which can effectively suppress the influence of back side of the double-side-coated electrodes on capacity and EIS measurements in coin-cells. By tape-covering the unwanted side, the areal capacity of the desired investigated side of the electrode has been accurately measured with an experimental error of about 0.5% at various current densities, and accurate EIS measurements and analysis have been conducted as well.

Microhomology-mediated End Joining and Homologous Recombination share the initial end resection step to repair DNA double-strand breaks in mammalian cells

PubMed Central

Truong, Lan N.; Li, Yongjiang; Shi, Linda Z.; Hwang, Patty Yi-Hwa; He, Jing; Wang, Hailong; Razavian, Niema; Berns, Michael W.; Wu, Xiaohua

2013-01-01

Microhomology-mediated end joining (MMEJ) is a major pathway for Ku-independent alternative nonhomologous end joining, which contributes to chromosomal translocations and telomere fusions, but the underlying mechanism of MMEJ in mammalian cells is not well understood. In this study, we demonstrated that, distinct from Ku-dependent classical nonhomologous end joining, MMEJ—even with very limited end resection—requires cyclin-dependent kinase activities and increases significantly when cells enter S phase. We also showed that MMEJ shares the initial end resection step with homologous recombination (HR) by requiring meiotic recombination 11 homolog A (Mre11) nuclease activity, which is needed for subsequent recruitment of Bloom syndrome protein (BLM) and exonuclease 1 (Exo1) to DNA double-strand breaks (DSBs) to promote extended end resection and HR. MMEJ does not require S139-phosphorylated histone H2AX (γ-H2AX), suggesting that initial end resection likely occurs at DSB ends. Using a MMEJ and HR competition repair substrate, we demonstrated that MMEJ with short end resection is used in mammalian cells at the level of 10–20% of HR when both HR and nonhomologous end joining are available. Furthermore, MMEJ is used to repair DSBs generated at collapsed replication forks. These studies suggest that MMEJ not only is a backup repair pathway in mammalian cells, but also has important physiological roles in repairing DSBs to maintain cell viability, especially under genomic stress. PMID:23610439

GC-Rich Extracellular DNA Induces Oxidative Stress, Double-Strand DNA Breaks, and DNA Damage Response in Human Adipose-Derived Mesenchymal Stem Cells

PubMed Central

Smirnova, Tatiana; Kameneva, Larisa; Porokhovnik, Lev; Speranskij, Anatolij; Ershova, Elizaveta; Stukalov, Sergey; Izevskaya, Vera; Veiko, Natalia

2015-01-01

Background. Cell free DNA (cfDNA) circulates throughout the bloodstream of both healthy people and patients with various diseases. CfDNA is substantially enriched in its GC-content as compared with human genomic DNA. Principal Findings. Exposure of haMSCs to GC-DNA induces short-term oxidative stress (determined with H2DCFH-DA) and results in both single- and double-strand DNA breaks (comet assay and γH2AX, foci). As a result in the cells significantly increases the expression of repair genes (BRCA1 (RT-PCR), PCNA (FACS)) and antiapoptotic genes (BCL2 (RT-PCR and FACS), BCL2A1, BCL2L1, BIRC3, and BIRC2 (RT-PCR)). Under the action of GC-DNA the potential of mitochondria was increased. Here we show that GC-rich extracellular DNA stimulates adipocyte differentiation of human adipose-derived mesenchymal stem cells (haMSCs). Exposure to GC-DNA leads to an increase in the level of RNAPPARG2 and LPL (RT-PCR), in the level of fatty acid binding protein FABP4 (FACS analysis) and in the level of fat (Oil Red O). Conclusions. GC-rich fragments in the pool of cfDNA can potentially induce oxidative stress and DNA damage response and affect the direction of mesenchymal stem cells differentiation in human adipose—derived mesenchymal stem cells. Such a response may be one of the causes of obesity or osteoporosis. PMID:26273425

Photovoltaic performance and stability of fullerene/cerium oxide double electron transport layer superior to single one in p-i-n perovskite solar cells

NASA Astrophysics Data System (ADS)

Xing, Zhou; Li, Shu-Hui; Wu, Bao-Shan; Wang, Xin; Wang, Lu-Yao; Wang, Tan; Liu, Hao-Ran; Zhang, Mei-Lin; Yun, Da-Qin; Deng, Lin-Long; Xie, Su-Yuan; Huang, Rong-Bin; Zheng, Lan-Sun

2018-06-01

Interface engineering that involves in the metal cathodes and the electron transport layers (ETLs) facilitates the simultaneous improvement of device performances and stability in perovskite solar cells (PSCs). Herein, low-temperature solution-processed cerium oxide (CeOx) films are prepared by a facile sol-gel method and employed as the interface layers between [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) and an Ag back contact to form PC61BM/CeOx double ETLs. The introduction of CeOx enables electron extraction to the Ag electrode and protects the underlying perovskite layer and thus improves the device performance and stability of the p-i-n PSCs. The p-i-n PSCs with double PC61BM/CeOx ETLs demonstrate a maximum power conversion efficiency (PCE) of 17.35%, which is superior to those of the devices with either PC61BM or CeOx single ETLs. Moreover, PC61BM/CeOx devices exhibit excellent stability in light soaking, which is mainly due to the chemically stable CeOx interlayer. The results indicate that CeOx is a promising interface modification layer for stable high-efficiency PSCs.

Assaying effector function in planta using double-barreled particle bombardment.

PubMed

Kale, Shiv D; Tyler, Brett M

2011-01-01

The biolistic transient gene expression assay is a beneficial tool for studying gene function in vivo. However, biolistic transient assay systems have inherent pitfalls that often cause experimental inaccuracies such as poor transformation efficiency, which can be confused with biological phenomena. The double-barreled gene gun device is an inexpensive and highly effective attachment that enables statistically significant data to be obtained with one-tenth the number of experimental replicates compared to conventional biolistic assays. The principle behind the attachment is to perform two simultaneous bombardments with control and test DNA preparations onto the same leaf. The control bombardment measures the efficiency of the transformation while the ratio of the test bombardment to the control bombardment measures the activity of the gene of interest. With care, the ratio between the pair of bombardments can be highly reproducible from bombardment to bombardment. The double-barreled attachment has been used to study plant resistance (R) gene-mediated responses to effectors, induction and suppression of cell death by a wide variety of pathogen and host molecules, and the role of oömycete effector RXLR motifs in cell reentry.

Persistent 3'-phosphate termini and increased cytotoxicity of radiomimetic DNA double-strand breaks in cells lacking polynucleotide kinase/phosphatase despite presence of an alternative 3'-phosphatase.

PubMed

Chalasani, Sri Lakshmi; Kawale, Ajinkya S; Akopiants, Konstantin; Yu, Yaping; Fanta, Mesfin; Weinfeld, Michael; Povirk, Lawrence F

2018-05-25

Polynucleotide kinase/phosphatase (PNKP) has been implicated in non-homologous end joining (NHEJ) of DNA double-strand breaks (DSBs). To assess the consequences of PNKP deficiency for NHEJ of 3'-phosphate-ended DSBs, PNKP-deficient derivatives of HCT116 and of HeLa cells were generated using CRISPR/CAS9. For both cell lines, PNKP deficiency conferred sensitivity to ionizing radiation as well as to neocarzinostatin (NCS), which specifically induces DSBs bearing protruding 3'-phosphate termini. Moreover, NCS-induced DSBs, detected as 53BP1 foci, were more persistent in PNKP -/- HCT116 cells compared to their wild-type (WT) counterparts. Surprisingly, PNKP-deficient whole-cell and nuclear extracts were biochemically competent in removing both protruding and recessed 3'-phosphates from synthetic DSB substrates, albeit much less efficiently than WT extracts, suggesting an alternative 3'-phosphatase. Measurements by ligation-mediated PCR showed that PNKP-deficient HeLa cells contained significantly more 3'-phosphate-terminated and fewer 3'-hydroxyl-terminated DSBs than parental cells 5-15 min after NCS treatment, but this difference disappeared by 1 h. These results suggest that, despite presence of an alternative 3'-phosphatase, loss of PNKP significantly sensitizes cells to 3'-phosphate-terminated DSBs, due to a 3'-dephosphorylation defect. Copyright © 2018 Elsevier B.V. All rights reserved.

Curvature of Double-Membrane Organelles Generated by Changes in Membrane Size and Composition

PubMed Central

Knorr, Roland L.; Dimova, Rumiana; Lipowsky, Reinhard

2012-01-01

Transient double-membrane organelles are key players in cellular processes such as autophagy, reproduction, and viral infection. These organelles are formed by the bending and closure of flat, double-membrane sheets. Proteins are believed to be important in these morphological transitions but the underlying mechanism of curvature generation is poorly understood. Here, we describe a novel mechanism for this curvature generation which depends primarily on three membrane properties: the lateral size of the double-membrane sheets, the molecular composition of their highly curved rims, and a possible asymmetry between the two flat faces of the sheets. This mechanism is evolutionary advantageous since it does not require active processes and is readily available even when resources within the cell are restricted as during starvation, which can induce autophagy and sporulation. We identify pathways for protein-assisted regulation of curvature generation, organelle size, direction of bending, and morphology. Our theory also provides a mechanism for the stabilization of large double-membrane sheet-like structures found in the endoplasmic reticulum and in the Golgi cisternae. PMID:22427874

Discrete Boltzmann Method with Maxwell-Type Boundary Condition for Slip Flow

NASA Astrophysics Data System (ADS)

Zhang, Yu-Dong; Xu, Ai-Guo; Zhang, Guang-Cai; Chen, Zhi-Hua

2018-01-01

The rarefied effect of gas flow in microchannel is significant and cannot be well described by traditional hydrodynamic models. It has been known that discrete Boltzmann model (DBM) has the potential to investigate flows in a relatively wider range of Knudsen number because of its intrinsic kinetic nature inherited from Boltzmann equation. It is crucial to have a proper kinetic boundary condition for DBM to capture the velocity slip and the flow characteristics in the Knudsen layer. In this paper, we present a DBM combined with Maxwell-type boundary condition model for slip flow. The tangential momentum accommodation coefficient is introduced to implement a gas-surface interaction model. Both the velocity slip and the Knudsen layer under various Knudsen numbers and accommodation coefficients can be well described. Two kinds of slip flows, including Couette flow and Poiseuille flow, are simulated to verify the model. To dynamically compare results from different models, the relation between the definition of Knudsen number in hard sphere model and that in BGK model is clarified. Support of National Natural Science Foundation of China under Grant Nos. 11475028, 11772064, and 11502117 Science Challenge Project under Grant Nos. JCKY2016212A501 and TZ2016002

Hesr1 and Hesr3 are essential to generate undifferentiated quiescent satellite cells and to maintain satellite cell numbers

PubMed Central

Fukada, So-ichiro; Yamaguchi, Masahiko; Kokubo, Hiroki; Ogawa, Ryo; Uezumi, Akiyoshi; Yoneda, Tomohiro; Matev, Miroslav M.; Motohashi, Norio; Ito, Takahito; Zolkiewska, Anna; Johnson, Randy L.; Saga, Yumiko; Miyagoe-Suzuki, Yuko; Tsujikawa, Kazutake; Takeda, Shin’ichi; Yamamoto, Hiroshi

2011-01-01

Satellite cells, which are skeletal muscle stem cells, divide to provide new myonuclei to growing muscle fibers during postnatal development, and then are maintained in an undifferentiated quiescent state in adult skeletal muscle. This state is considered to be essential for the maintenance of satellite cells, but their molecular regulation is unknown. We show that Hesr1 (Hey1) and Hesr3 (Heyl) (which are known Notch target genes) are expressed simultaneously in skeletal muscle only in satellite cells. In Hesr1 and Hesr3 single-knockout mice, no obvious abnormalities of satellite cells or muscle regenerative potentials are observed. However, the generation of undifferentiated quiescent satellite cells is impaired during postnatal development in Hesr1/3 double-knockout mice. As a result, myogenic (MyoD and myogenin) and proliferative (Ki67) proteins are expressed in adult satellite cells. Consistent with the in vivo results, Hesr1/3-null myoblasts generate very few Pax7+ MyoD– undifferentiated cells in vitro. Furthermore, the satellite cell number gradually decreases in Hesr1/3 double-knockout mice even after it has stabilized in control mice, and an age-dependent regeneration defect is observed. In vivo results suggest that premature differentiation, but not cell death, is the reason for the reduced number of satellite cells in Hesr1/3 double-knockout mice. These results indicate that Hesr1 and Hesr3 are essential for the generation of adult satellite cells and for the maintenance of skeletal muscle homeostasis. PMID:21989910

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babac, Gulru

Gas flow in micro/nano scale systems has been generally studied for the Maxwell gases. In the limits of very low temperature and very confined domains, the Maxwellian approximation can break down and the quantum character of the gases becomes important. In these cases, Knudsen law, which is one of the important equations to analyze rarefied gas flows is invalid and should be reanalyzed for quantum gases. In this work, the availability of quantum gas conditions in the high Knudsen number cases is discussed and Knudsen law is analyzed for quantum gases.

Acetaminophen degradation by electro-Fenton and photoelectro-Fenton using a double cathode electrochemical cell.

PubMed

de Luna, Mark Daniel G; Veciana, Mersabel L; Su, Chia-Chi; Lu, Ming-Chun

2012-05-30

Acetaminophen is a widely used drug worldwide and is one of the most frequently detected in bodies of water making it a high priority trace pollutant. This study investigated the applicability of the electro-Fenton and photoelectro-Fenton processes using a double cathode electrochemical cell in the treatment of acetaminophen containing wastewater. The Box-Behnken design was used to determine the effects of initial Fe(2+) and H(2)O(2) concentrations and applied current density. Results showed that all parameters positively affected the degradation efficiency of acetaminophen with the initial Fe(2+) concentration being the most significant parameter for both processes. The acetaminophen removal efficiency for electro-Fenton was 98% and chemical oxygen demand (COD) removal of 43% while a 97% acetaminophen removal and 42% COD removal were observed for the photoelectro-Fenton method operated at optimum conditions. The electro-Fenton process was only able to obtain 19% total organic carbon (TOC) removal while the photoelectro-Fenton process obtained 20%. Due to negligible difference between the treatment efficiencies of the two processes, the electro-Fenton method was proven to be more economically advantageous. The models obtained from the study were applicable to a wide range of acetaminophen concentrations and can be used in scale-ups. Thirteen different types of intermediates were identified and a degradation pathway was proposed. Copyright © 2012 Elsevier B.V. All rights reserved.

Identification of Hürthle cell tumor by single-injection, double-phase scintigraphy with technetium-99m-sestamibi.

PubMed

Vattimo, A; Bertelli, P; Cintorino, M; Burroni, L; Volterrani, D; Vella, A

1995-05-01

Early and late (double-phase) scintigraphy with 99mTc-MIBI was used in a comparative study of the scintigraphic aspects of Hürthle cell tumors and other thyroid tumors. Single-injection, dual-phase (15-30 min and 3-4 hr) thyroid scintigraphy with 99mTc-sestamibi (MIBI) was performed on 41 patients who displayed a cold nodule on previous 99mTc scintigraphy. Visual scoring of nodular uptake was done to compare thyroidal and background tracer uptake. In addition, the nodular-to-thyroid (N/T) uptake ratio in the early and late images and the washout rate from the nodule (WON) and thyroidal tissue (WOT) were measured. Cytologic results were obtained for all patients; histopathologic results were obtained for the 20 patients who had surgery. In eight patients (Group A), the nodule displayed intense and persistent uptake of MIBI (N/T = 1.77 +/- 0.46 and 3.20 +/- 1.37; WON = 17.2% +/- 6.3%; WOT = 24.6% +/- 7.5%); histopathology revealed Hürthle cell tumors (two carcinomas and three adenomas) in five surgical patients. In 15 patients (Group B), the nodule displayed intense uptake in the early image with fading activity in the late image (N/T = 1.45 +/- 0.54 and 0.84 +/- 0.30; WON = 30.0% +/- 7.3%; WOT = 24.5% +/- 6.8%); histopathology revealed a colloid nodule (n = 1), papillary carcinoma (n = 4) and follicular carcinoma (n = 5) in 10 surgical patients. In the remaining 18 patients (Group C), the nodule was cold and late images were not acquired. Histopathology revealed colloid nodules (n = 2) and follicular adenoma (n = 3) in five surgical patients. Single-injection, dual-phase MIBI scintigraphy of the thyroid can identify Hürthle cell tumors because these tumors have intense, persistent tracer uptake in contrast to other thyroid tumors.

High performance planar p-i-n perovskite solar cells with crown-ether functionalized fullerene and LiF as double cathode buffer layers

NASA Astrophysics Data System (ADS)

Liu, Xiaodong; Lei, Ming; Zhou, Yi; Song, Bo; Li, Yongfang

2015-08-01

Double cathode buffer layers (CBLs) composed of fullerene derivative functionalized with a crown-ether end group in its side chain (denoted as PCBC) and a LiF layer were introduced between the PCBM acceptor layer and the top cathode in planar p-i-n perovskite solar cells (pero-SCs) based on CH3NH3PbI3-XClX. The devices with the PCBC/LiF double CBLs showed significant improvements in power conversion efficiency (PCE) and long-term stability when compared to the device with LiF single CBL. Through optimizing the spin-coating speed of PCBC, a maximum PCE of 15.53% has been achieved, which is approximately 15% higher than that of the device with single LiF CBL. The remarkable improvement in PCE can be attributed to the formation of a better ohmic contact in the CBL between PCBC and LiF/Al electrode arising from the dipole moment of PCBC, leading to the enhanced fill factor and short-circuit current density (Jsc). Besides the PCE, the long-term stability of the devices with PCBC interlayer is also superior to that of the device with LiF single CBL, which is due to the more effective protection for the perovskite/PCBM interface.

Who is entitled to double effect?

PubMed

Boyle, J

1991-10-01

The doctrine of double effect continues to be an important tool in bioethical casuistry. Its role within the Catholic moral tradition continues, and there is considerable interest in it by contemporary moral philosophers. But problems of justification and correct application remain. I argue that if the traditional Catholic conviction that there are exceptionless norms prohibiting inflicting some kinds of harms on people is correct, then double effect is justified and necessary. The objection that double effect is superfluous is a rejection of that normative conviction, not a refutation of double effect itself. This justification suggests the correct way of applying double effect to controversial cases. But versions of double effect which dispense with the absolutism of the Catholic tradition lack justification and fall to the objection that double effect is an unnecessary complication.

Flagellar membrane fusion and protein exchange in trypanosomes; a new form of cell-cell communication?

PubMed Central

Imhof, Simon; Fragoso, Cristina; Hemphill, Andrew; von Schubert, Conrad; Li, Dong; Legant, Wesley; Betzig, Eric; Roditi, Isabel

2016-01-01

Diverse structures facilitate direct exchange of proteins between cells, including plasmadesmata in plants and tunnelling nanotubes in bacteria and higher eukaryotes.  Here we describe a new mechanism of protein transfer, flagellar membrane fusion, in the unicellular parasite Trypanosoma brucei. When fluorescently tagged trypanosomes were co-cultured, a small proportion of double-positive cells were observed. The formation of double-positive cells was dependent on the presence of extracellular calcium and was enhanced by placing cells in medium supplemented with fresh bovine serum. Time-lapse microscopy revealed that double-positive cells arose by bidirectional protein exchange in the absence of nuclear transfer.  Furthermore, super-resolution microscopy showed that this process occurred in ≤1 minute, the limit of temporal resolution in these experiments. Both cytoplasmic and membrane proteins could be transferred provided they gained access to the flagellum. Intriguingly, a component of the RNAi machinery (Argonaute) was able to move between cells, raising the possibility that small interfering RNAs are transported as cargo. Transmission electron microscopy showed that shared flagella contained two axonemes and two paraflagellar rods bounded by a single membrane. In some cases flagellar fusion was partial and interactions between cells were transient. In other cases fusion occurred along the entire length of the flagellum, was stable for several hours and might be irreversible. Fusion did not appear to be deleterious for cell function: paired cells were motile and could give rise to progeny while fused. The motile flagella of unicellular organisms are related to the sensory cilia of higher eukaryotes, raising the possibility that protein transfer between cells via cilia or flagella occurs more widely in nature. PMID:27239276

A grid-doubling finite-element technique for calculating dynamic three-dimensional spontaneous rupture on an earthquake fault

USGS Publications Warehouse

Barall, Michael

2009-01-01

We present a new finite-element technique for calculating dynamic 3-D spontaneous rupture on an earthquake fault, which can reduce the required computational resources by a factor of six or more, without loss of accuracy. The grid-doubling technique employs small cells in a thin layer surrounding the fault. The remainder of the modelling volume is filled with larger cells, typically two or four times as large as the small cells. In the resulting non-conforming mesh, an interpolation method is used to join the thin layer of smaller cells to the volume of larger cells. Grid-doubling is effective because spontaneous rupture calculations typically require higher spatial resolution on and near the fault than elsewhere in the model volume. The technique can be applied to non-planar faults by morphing, or smoothly distorting, the entire mesh to produce the desired 3-D fault geometry. Using our FaultMod finite-element software, we have tested grid-doubling with both slip-weakening and rate-and-state friction laws, by running the SCEC/USGS 3-D dynamic rupture benchmark problems. We have also applied it to a model of the Hayward fault, Northern California, which uses realistic fault geometry and rock properties. FaultMod implements fault slip using common nodes, which represent motion common to both sides of the fault, and differential nodes, which represent motion of one side of the fault relative to the other side. We describe how to modify the traction-at-split-nodes method to work with common and differential nodes, using an implicit time stepping algorithm.

Laboratory observation of multiple double layer resembling space plasma double layer

NASA Astrophysics Data System (ADS)

Alex, Prince; Arumugam, Saravanan; Sinha, Suraj

2017-10-01

Perceptible double layer consisting of more than one layers were produced in laboratory using a double discharge plasma setup. The confinement of oppositely charged particles in each layer with sharply defined luminous boarder is attributed to the self-organization scenario. This structure is generated in front of a positively biased electrode when the electron drift velocity (νd) exceeds 1.3 times the electron thermal velocity (νte) . Stable multiple double layer structures were observed only between 1.3 νte <=νd <= 3 νte. At νd = 1.3 νte, oscillations were excited in the form of large amplitude burst followed by a high frequency stable oscillation. Beyond νd = 3 νte, multiple double layer begins to collapse which is characterized by an emergence in turbulence. Long range dependence in the corresponding electrostatic potential fluctuations indicates the role of self-organized criticality in the emergence of turbulence. The algebraic decaying tale of the autocorrelation function and power law behavior in the power spectrum are consistent with the observation.

Synoptic Formation of Double Tropopauses

NASA Astrophysics Data System (ADS)

Liu, Chengji; Barnes, Elizabeth

2018-01-01

Double tropopauses are ubiquitous in the midlatitude winter hemisphere and represent the vertical stacking of two stable tropopause layers separated by a less stable layer. By analyzing COSMIC GPS data, reanalysis, and eddy life cycle simulations, we demonstrate that they often occur during Rossby wave breaking and act to increase the stratosphere-to-troposphere exchange of mass. We further investigate the adiabatic formation of double tropopauses and propose two mechanisms by which they can occur. The first mechanism operates at the tropopause break in the subtropics where the higher tropical tropopause sits on one side of the break and the lower extratropical tropopause sits on the other. The double tropopauses are then formed by differential meridional advection of the higher and lower tropopauses on the two sides of the tropopause break. We show that anticyclonic wave breaking can form double tropopauses mainly by providing stronger poleward advection of the higher tropopause in its poleward lobe. Cyclonic wave breaking mainly forms double tropopauses by providing stronger equatorward advection of the lower tropopause in its equatorward lobe. We demonstrate in the COSMIC GPS data and reanalysis that about half of the double tropopauses in the Northern Hemisphere winter can be directly attributed to such differential advection. For the second mechanism, adiabatic destabilization of the air above the tropopause contributes to the formation of a double tropopause. In this case, a tropopause inversion layer is necessary for this destabilization to result in a double tropopause.

Radiosensitization of tumour cell lines by the polyphenol Gossypol results from depressed double-strand break repair and not from enhanced apoptosis.

PubMed

Kasten-Pisula, Ulla; Windhorst, Sabine; Dahm-Daphi, Jochen; Mayr, Georg; Dikomey, Ekkehard

2007-06-01

New drugs are needed to increase the efficiency of radiotherapy in order to improve the therapeutic outcome of tumour patients. In this respect, the polyphenol Gossypol might be of interest, because of its effect on apoptosis and DNA repair, which is either mediated directly or indirectly via the inositol phosphate metabolism. It was investigated, whether these effects result in enhanced radiosensitivity of tumour cells. Tumour cell lines investigated: A549, FaDu, H1299, MCF7 and Du145. Cell cycle distribution was determined by FACS analysis, apoptosis was measured by DAPI staining and caspase3/7 activity. Double-strand breaks (DSB) were investigated via gammaH2AX-foci and cell survival by colony formation assay. The level of inositol phosphates was determined by HPLC, protein expression by Western blot. In A549 cells, Gossypol at concentrations 1microM strongly affects proliferation with only a modest arrest in the G1-phase, but with no increase in the fraction of apoptotic cells or the number of additional DSB. Additional DSB were only seen in FaDu cells, where Gossypol (2microM) was extremely toxic with a plating efficiency <0.002. When combined with irradiation, incubation with Gossypol (1-2microM) was found to result in an enhanced radiosensitivity with, however, a substantial variation. While there was a strong radiosensitization for FaDu and Du145 cells, there was an intermediate response for A549 cells, but almost no effect for H1299 and MCF7 cells. This sensitization was not caused from an elevated rate of apoptosis, but primarily resulted from reduced DSB repair capacity. The reduction in DSB repair could be ascribed neither to changes in the level of repair proteins relevant for non-homologous end-joining (Ku70, Ku80, DNA-PKcs) nor to changes in the level of higher phosphorylated inositols, whereby the latter were even found to be enhanced by Gossypol. For some tumour cell lines treatment with low concentrations of Gossypol can be used to inhibit DSB

Parity-Forbidden Transitions and Their Impact on the Optical Absorption Properties of Lead-Free Metal Halide Perovskites and Double Perovskites.

PubMed

Meng, Weiwei; Wang, Xiaoming; Xiao, Zewen; Wang, Jianbo; Mitzi, David B; Yan, Yanfa

2017-07-06

Using density functional theory calculations, we analyze the optical absorption properties of lead (Pb)-free metal halide perovskites (AB 2+ X 3 ) and double perovskites (A 2 B + B 3+ X 6 ) (A = Cs or monovalent organic ion, B 2+ = non-Pb divalent metal, B + = monovalent metal, B 3+ = trivalent metal, X = halogen). We show that if B 2+ is not Sn or Ge, Pb-free metal halide perovskites exhibit poor optical absorptions because of their indirect band gap nature. Among the nine possible types of Pb-free metal halide double perovskites, six have direct band gaps. Of these six types, four show inversion symmetry-induced parity-forbidden or weak transitions between band edges, making them not ideal for thin-film solar cell applications. Only one type of Pb-free double perovskite shows optical absorption and electronic properties suitable for solar cell applications, namely, those with B + = In, Tl and B 3+ = Sb, Bi. Our results provide important insights for designing new metal halide perovskites and double perovskites for optoelectronic applications.

Absence of Tec Family Kinases Interleukin-2 Inducible T cell Kinase (Itk) and Bruton's Tyrosine Kinase (Btk) Severely Impairs FcϵRI-dependent Mast Cell Responses*

PubMed Central

Iyer, Archana S.; Morales, J. Luis; Huang, Weishan; Ojo, Folake; Ning, Gang; Wills, Elizabeth; Baines, Joel D.; August, Avery

2011-01-01

Mast cells are critical effector cells in the pathophysiology of allergic asthma and other IgE-mediated diseases. The Tec family of tyrosine kinases Itk and Btk serve as critical signal amplifiers downstream of antigen receptors. Although both kinases are expressed and activated in mast cells following FcϵRI stimulation, their individual contributions are not clear. To determine whether these kinases play unique and/or complementary roles in FcϵRI signaling and mast cell function, we generated Itk and Btk double knock-out mice. Analyses of these mice show decreased mast cell granularity and impaired passive systemic anaphylaxis responses. This impaired response is accompanied by a significant elevation in serum IgE in Itk/Btk double knock-out mice. In vitro analyses of bone marrow-derived mast cells (BMMCs) indicated that Itk/Btk double knock-out BMMCs are defective in degranulation and cytokine secretion responses downstream to FcϵRI activation. These responses were accompanied by a significant reduction in PLCγ2 phosphorylation and severely impaired calcium responses in these cells. This defect also results in altered NFAT1 nuclear localization in double knock-out BMMCs. Network analysis suggests that although they may share substrates, Itk plays both positive and negative roles, while Btk primarily plays a positive role in mast cell FcϵRI-induced cytokine secretion. PMID:21212279

Technology Solutions Case Study: Monitoring of Double Stud Wall Moisture Conditions in the Northeast, Devens, Massachusetts

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2015-03-01

Double stud walls have a higher risk of interior-sourced condensation moisture damage when compared with high-R approaches using exterior insulating sheathing. In this project, Building Science Corporation monitored moisture conditions in double-stud walls from 2011 through 2014 at a new production house located in Devens, Massachusetts. The builder, Transformations, Inc., has been using double-stud walls insulated with 12 in. of open cell polyurethane spray foam (ocSPF); however, the company has been considering a change to netted and blown cellulose insulation for cost reasons. Cellulose is a common choice for double-stud walls because of its lower cost (in most markets). However,more » cellulose is an air-permeable insulation, unlike spray foams, which increases interior moisture risks. The team compared three double-stud assemblies: 12 in. of ocSPF, 12 in. of cellulose, and 5-½ in. of ocSPF at the exterior of a double-stud wall (to approximate conventional 2 × 6 wall construction and insulation levels, acting as a control wall). These assemblies were repeated on the north and south orientations, for a total of six assemblies.« less

Inhalation aromatherapy in children and adolescents undergoing stem cell infusion: results of a placebo-controlled double-blind trial.

PubMed

Ndao, Deborah H; Ladas, Elena J; Cheng, Bin; Sands, Stephen A; Snyder, Kathryn T; Garvin, James H; Kelly, Kara M

2012-03-01

Though often lifesaving, stem cell transplantation (SCT) is a period of great distress for both child and parent. We conducted a double-blind, placebo-controlled randomized study evaluating the effect of the respiratory administration of bergamot essential oil on the anxiety, nausea, and pain of 37 pediatric patients with malignant and non-malignant disorders undergoing stem cell infusion and their parents. Patients were assessed at the time of recruitment, prior to infusion, upon infusion completion, and one hour post-infusion using the Spielberger State-Trait Anxiety Inventory (STAI) for parents and the STAIC, Children's Behavioral Style Scale (CBSS), visual analogue scale (VAS) for pain and nausea, and the Emotionality Activity Sociability and Impulsivity instrument (EASI) for children. Children and adolescents in the treatment group experienced greater anxiety (p = 0.05) and nausea (p = 0.03) one hour post-infusion. Reported pain in both groups was no longer significant one hour post-infusion. Parental anxiety declined in both groups but did not reach statistical significance. Child's monitoring coping style was significantly predictive of transitory anxiety post-infusion (p = 0.01). Although this trial did not report a benefit of inhalation aromatherapy for reducing anxiety, nausea, or pain when added to standard supportive care, it provides the first experimental rather than descriptive report on testing a single therapeutic essential oil among children and adolescents undergoing stem cell infusion. Future research may consider exploring the cutaneous application of essential oil through massage or other psychoeducational counseling interventions among parents with elevated anxiety and patients with greater information seeking coping styles during SCT. Copyright © 2010 John Wiley & Sons, Ltd.

Lack of dependence on p53 for DNA double strand break repair of episomal vectors in human lymphoblasts

NASA Technical Reports Server (NTRS)

Kohli, M.; Jorgensen, T. J.

1999-01-01

The p53 tumor suppressor gene has been shown to be involved in a variety of repair processes, and recent findings have suggested that p53 may be involved in DNA double strand break repair in irradiated cells. The role of p53 in DNA double strand break repair, however, has not been fully investigated. In this study, we have constructed a novel Epstein-Barr virus (EBV)-based shuttle vector, designated as pZEBNA, to explore the influence of p53 on DNA strand break repair in human lymphoblasts, since EBV-based vectors do not inactivate the p53 pathway. We have compared plasmid survival of irradiated, restriction enzyme linearized, and calf intestinal alkaline phosphatase (CIP)-treated pZEBNA with a Simian virus 40 (SV40)-based shuttle vector, pZ189, in TK6 (wild-type p53) and WTK1 (mutant p53) lymphoblasts and determined that p53 does not modulate DNA double strand break repair in these cell lines. Copyright 1999 Academic Press.

Production of Exocytic Vesicular Antigens by Primary Liver Cell Cultures

DTIC Science & Technology

1990-05-08

cells should be plated over the basement membrane proteins, and for optimal results, a second layer of protein should be precipitated over the cells...culture as two layer (two gelatin coated nylon sheets stapled together) and single layer carriers seeded with cells (Table 2). From the performance results...summarized in table 2, it can be seen that double sheets of 2% gelatin: 6% glutaraldehyde (carrier II) made the best carriers. A double layer of

Fetal progenitor cell transplantation treats methylmalonic aciduria in a mouse model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buck, Nicole E., E-mail: nicole.buck@mcri.edu.au; Pennell, Samuel D.; Wood, Leonie R.

Highlights: Black-Right-Pointing-Pointer Fetal cells were transplanted into a methylmalonic acid mouse model. Black-Right-Pointing-Pointer Cell engraftment was detected in liver, spleen and bone marrow. Black-Right-Pointing-Pointer Biochemical disease correction was measured in blood samples. Black-Right-Pointing-Pointer A double dose of 5 million cells (1 week apart) proved more effective. Black-Right-Pointing-Pointer Higher levels of engraftment may be required for greater disease correction. -- Abstract: Methylmalonic aciduria is a rare disorder caused by an inborn error of organic acid metabolism. Current treatment options are limited and generally focus on disease management. We aimed to investigate the use of fetal progenitor cells to treat this disordermore » using a mouse model with an intermediate form of methylmalonic aciduria. Fetal liver cells were isolated from healthy fetuses at embryonic day 15-17 and intravenously transplanted into sub-lethally irradiated mice. Liver donor cell engraftment was determined by PCR. Disease correction was monitored by urine and blood methylmalonic acid concentration and weight change. Initial studies indicated that pre-transplantation sub-lethal irradiation followed by transplantation with 5 million cells were suitable. We found that a double dose of 5 million cells (1 week apart) provided a more effective treatment. Donor cell liver engraftment of up to 5% was measured. Disease correction, as defined by a decrease in blood methylmalonic acid concentration, was effected in methylmalonic acid mice transplanted with a double dose of cells and who showed donor cell liver engraftment. Mean plasma methylmalonic acid concentration decreased from 810 {+-} 156 (sham transplanted) to 338 {+-} 157 {mu}mol/L (double dose of 5 million cells) while mean blood C3 carnitine concentration decreased from 20.5 {+-} 4 (sham transplanted) to 5.3 {+-} 1.9 {mu}mol/L (double dose of 5 million cells). In conclusion, higher levels of

Effect of Initiation Time of Hydrostatic Pressure Shock on Chromosome Set Doubling of Tetraploidization in Turbot Scophthalmus maximus.

PubMed

Zhu, Xiangping; Lin, Zhengmei; Wu, Zhihao; Li, Jiandong; You, Feng

2017-10-01

The objective of the study was to clarify the effects of initiation time on chromosome set doubling induced by hydrostatic pressure shock through nuclear phase fluorescent microscopy in turbot Scophthalmus maximus. The ratio of developmentally delayed embryo and chromosome counting was used to assess induction efficiency. For the embryos subjected to a pressure of 67.5 MPa for 6 min at prometaphase (A group), chromosomes recovered to the pre-treatment condition after 11-min recovering. The first nuclear division and cytokinesis proceeded normally. During the second cell cycle, chromosomes did not enter into metaphase after prometaphase, but spread around for about 13 min, then assembled together and formed a large nucleus without anaphase separation; the second nuclear division and cytokinesis was inhibited. The ratio of developmentally delayed embryo showed that the second mitosis of 78% A group embryo was inhibited. The result of chromosome counting showed that the tetraploidization rate of A group was 72%. For the embryos subjected to a pressure of 67.5 MPa for 6 min at anaphase (B group), chromosomes recovered to the pre-treatment condition after about 31-min recovering. Afterwards, one telophase nucleus formed without anaphase separation; the first nuclear division was inhibited. The time of the first cleavage furrow occurrence of B group embryos delayed 27 min compared with that of A group embryos. With the first cytokinesis proceeding normally, 81.3% B group embryos were at two-cell stage around the middle of the second cell cycle after treatment. Those embryos were one of the two blastomeres containing DNA and the other without DNA. The first nuclear division of those embryos was inhibited. During the third cell cycle after treatment, 65.2% of those abovementioned embryos were at four-cell stage, cytokinesis occurred in both blastomeres, and nuclear division only occurred in the blastomere containing DNA. Of those abovementioned embryos, 14.0% were at

Bandgap Engineering of Stable Lead-Free Oxide Double Perovskites for Photovoltaics.

PubMed

Sun, Qingde; Wang, Jing; Yin, Wan-Jian; Yan, Yanfa

2018-04-01

Despite the rapid progress in solar power conversion efficiency of archetype organic-inorganic hybrid perovskite CH 3 NH 3 PbI 3 -based solar cells, the long-term stability and toxicity of Pb remain the main challenges for the industrial deployment, leading to more uncertainties for global commercialization. The poor stabilities of CH 3 NH 3 PbI 3 -based solar cells may not only be attributed to the organic molecules but also the halides themself, most of which exhibit intrinsic instability under moisture and light. As an alternative, the possibility of oxide perovskites for photovoltaic applications is explored here. The class of lead-free stable oxide double perovskites A 2 M(III)M(V)O 6 (A = Ca, Sr, Ba; M(III) = Sb 3+ or Bi 3+ ; M(V) = V 5+ , Nb 5+ , or Ta 5+ ) is comprehensively explored with regard to their stability and their electronic and optical properties. Apart from the strong stability, this class of double perovskites exhibits direct bandgaps ranging from 0.3 to 3.8 eV. With proper B site alloying, the bandgap can be tuned within the range of 1.0-1.6 eV with optical absorptions as strong as CH 3 NH 3 PbI 3 , making them suitable for efficient single-junction thin-film solar cell application. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Curcumin improves the efficacy of cisplatin by targeting cancer stem-like cells through p21 and cyclin D1-mediated tumour cell inhibition in non-small cell lung cancer cell lines

PubMed Central

BAHARUDDIN, PUTERI; SATAR, NAZILAH; FAKIRUDDIN, KAMAL SHAIK; ZAKARIA, NORASHIKIN; LIM, MOON NIAN; YUSOFF, NARAZAH MOHD; ZAKARIA, ZUBAIDAH; YAHAYA, BADRUL HISHAM

2016-01-01

Natural compounds such as curcumin have the ability to enhance the therapeutic effectiveness of common chemotherapy agents through cancer stem-like cell (CSC) sensitisation. In the present study, we showed that curcumin enhanced the sensitivity of the double-positive (CD166+/EpCAM+) CSC subpopulation in non-small cell lung cancer (NSCLC) cell lines (A549 and H2170) to cisplatin-induced apoptosis and inhibition of metastasis. Our results revealed that initial exposure of NSCLC cell lines to curcumin (10–40 µM) markedly reduced the percentage of viability to an average of ~51 and ~54% compared to treatment with low dose cisplatin (3 µM) with only 94 and 86% in both the A549 and H2170 cells. Moreover, sensitisation of NSCLC cell lines to curcumin through combined treatment enhanced the single effect induced by low dose cisplatin on the apoptosis of the double-positive CSC subpopulation by 18 and 20% in the A549 and H2170 cells, respectively. Furthermore, we found that curcumin enhanced the inhibitory effects of cisplatin on the highly migratory CD166+/EpCAM+ subpopulation, marked by a reduction in cell migration to 9 and 21% in the A549 and H2170 cells, respectively, indicating that curcumin may increase the sensitivity of CSCs to cisplatin-induced migratory inhibition. We also observed that the mRNA expression of cyclin D1 was downregulated, while a substantial increased in p21 expression was noted, followed by Apaf1 and caspase-9 activation in the double-positive (CD166+/EpCAM+) CSC subpopulation of A549 cells, suggested that the combined treatments induced cell cycle arrest, therefore triggering CSC growth inhibition via the intrinsic apoptotic pathway. In conclusion, we provided novel evidence of the previously unknown therapeutic effects of curcumin, either alone or in combination with cisplatin on the inhibition of the CD166+/EpCAM+ subpopulation of NSCLC cell lines. This finding demonstrated the potential therapeutic approach of using curcumin that may

Cell-type specific role of the RNA-binding protein, NONO, in the DNA double-strand break response in the mouse testes.

PubMed

Li, Shuyi; Shu, Feng-Jue; Li, Zhentian; Jaafar, Lahcen; Zhao, Shourong; Dynan, William S

2017-03-01

The tandem RNA recognition motif protein, NONO, was previously identified as a candidate DNA double-strand break (DSB) repair factor in a biochemical screen for proteins with end-joining stimulatory activity. Subsequent work showed that NONO and its binding partner, SFPQ, have many of the properties expected for bona fide repair factors in cell-based assays. Their contribution to the DNA damage response in intact tissue in vivo has not, however, been demonstrated. Here we compare DNA damage sensitivity in the testes of wild-type mice versus mice bearing a null allele of the NONO homologue (Nono gt ). In wild-type mice, NONO protein was present in Sertoli, peritubular myoid, and interstitial cells, with an increase in expression following induction of DNA damage. As expected for the product of an X-linked gene, NONO was not detected in germ cells. The Nono gt/0 mice had at most a mild testis developmental phenotype in the absence of genotoxic stress. However, following irradiation at sublethal, 2-4 Gy doses, Nono gt/0 mice displayed a number of indicators of radiosensitivity as compared to their wild-type counterparts. These included higher levels of persistent DSB repair foci, increased numbers of apoptotic cells in the seminiferous tubules, and partial degeneration of the blood-testis barrier. There was also an almost complete loss of germ cells at later times following irradiation, evidently arising as an indirect effect reflecting loss of stromal support. Results demonstrate a role for NONO protein in protection against direct and indirect biological effects of ionizing radiation in the whole animal. Copyright © 2017 Elsevier B.V. All rights reserved.

Generation of α1,3-galactosyltransferase and cytidine monophospho-N-acetylneuraminic acid hydroxylase gene double-knockout pigs

PubMed Central

MIYAGAWA, Shuji; MATSUNARI, Hitomi; WATANABE, Masahito; NAKANO, Kazuaki; UMEYAMA, Kazuhiro; SAKAI, Rieko; TAKAYANAGI, Shuko; TAKEISHI, Toki; FUKUDA, Tooru; YASHIMA, Sayaka; MAEDA, Akira; EGUCHI, Hiroshi; OKUYAMA, Hiroomi; NAGAYA, Masaki; NAGASHIMA, Hiroshi

2015-01-01

Zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs) are new tools for producing gene knockout (KO) animals. The current study reports produced genetically modified pigs, in which two endogenous genes were knocked out. Porcine fibroblast cell lines were derived from homozygous α1,3-galactosyltransferase (GalT) KO pigs. These cells were subjected to an additional KO for the cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH) gene. A pair of ZFN-encoding mRNAs targeting exon 8 of the CMAH gene was used to generate the heterozygous CMAH KO cells, from which cloned pigs were produced by somatic cell nuclear transfer (SCNT). One of the cloned pigs obtained was re-cloned after additional KO of the remaining CMAH allele using the same ZFN-encoding mRNAs to generate GalT/CMAH-double homozygous KO pigs. On the other hand, the use of TALEN-encoding mRNAs targeting exon 7 of the CMAH gene resulted in efficient generation of homozygous CMAH KO cells. These cells were used for SCNT to produce cloned pigs homozygous for a double GalT/CMAH KO. These results demonstrate that the combination of TALEN-encoding mRNA, in vitro selection of the nuclear donor cells and SCNT provides a robust method for generating KO pigs. PMID:26227017

Generation of α1,3-galactosyltransferase and cytidine monophospho-N-acetylneuraminic acid hydroxylase gene double-knockout pigs.

PubMed

Miyagawa, Shuji; Matsunari, Hitomi; Watanabe, Masahito; Nakano, Kazuaki; Umeyama, Kazuhiro; Sakai, Rieko; Takayanagi, Shuko; Takeishi, Toki; Fukuda, Tooru; Yashima, Sayaka; Maeda, Akira; Eguchi, Hiroshi; Okuyama, Hiroomi; Nagaya, Masaki; Nagashima, Hiroshi

2015-01-01

Zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs) are new tools for producing gene knockout (KO) animals. The current study reports produced genetically modified pigs, in which two endogenous genes were knocked out. Porcine fibroblast cell lines were derived from homozygous α1,3-galactosyltransferase (GalT) KO pigs. These cells were subjected to an additional KO for the cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH) gene. A pair of ZFN-encoding mRNAs targeting exon 8 of the CMAH gene was used to generate the heterozygous CMAH KO cells, from which cloned pigs were produced by somatic cell nuclear transfer (SCNT). One of the cloned pigs obtained was re-cloned after additional KO of the remaining CMAH allele using the same ZFN-encoding mRNAs to generate GalT/CMAH-double homozygous KO pigs. On the other hand, the use of TALEN-encoding mRNAs targeting exon 7 of the CMAH gene resulted in efficient generation of homozygous CMAH KO cells. These cells were used for SCNT to produce cloned pigs homozygous for a double GalT/CMAH KO. These results demonstrate that the combination of TALEN-encoding mRNA, in vitro selection of the nuclear donor cells and SCNT provides a robust method for generating KO pigs.

Scaling of volume to surface ratio and doubling time in growing unicellular organisms: Do cells appear quantum-mechanical systems?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atanasov, Atanas Todorov, E-mail: atanastod@abv.bg

2014-10-06

The scaling of physical and biological characteristics of the living organisms is a basic method for searching of new biophysical laws. In series of previous studies the author showed that in Poikilotherms, Mammals and Aves, the volume to surface ratio V×S{sup −1} (m) of organisms is proportional to their generation time T{sub gt}(s) via growth rate v (m s{sup −1}): V×S{sup −1} = v{sub gr}×T{sup r}. The power and the correlation coefficients are near to 1.0. Aim of this study is: i) to prove with experimental data the validity of the above equation for Unicellular organisms and ii) to show that perhaps,more » the cells are quantum-mechanical systems. The data for body mass M (kg), density ρ (kg/m{sup 3}), minimum and maximum doubling time T{sub dt} (s) for 50 unicellular organisms are assembled from scientific sources, and the computer program ‘Statistics’ is used for calculations. In result i) the analytical relationship from type: V×S{sup −1} = 4.46⋅10{sup −11}×T{sub dt} was found, where v{sub gr} = 4.46×10{sup −11} m/s and ii) it is shown that the products between cell mass M, cell length expressed by V/S ratio and growth rate v{sub gr} satisfied the Heisenberg uncertainty principle i.e. the inequalities V/S×M×v{sub gr}>h/2π and T{sub dt}×M×v{sub gr}{sup 2}>h/2π are valid, where h= 6.626×10{sup −34} J⋅s is the Planck constant. This rise the question: do cells appear quantum-mechanical systems?.« less

Mechanically activated artificial cell by using microfluidics

NASA Astrophysics Data System (ADS)

Ho, Kenneth K. Y.; Lee, Lap Man; Liu, Allen P.

2016-09-01

All living organisms sense mechanical forces. Engineering mechanosensitive artificial cell through bottom-up in vitro reconstitution offers a way to understand how mixtures of macromolecules assemble and organize into a complex system that responds to forces. We use stable double emulsion droplets (aqueous/oil/aqueous) to prototype mechanosensitive artificial cells. In order to demonstrate mechanosensation in artificial cells, we develop a novel microfluidic device that is capable of trapping double emulsions into designated chambers, followed by compression and aspiration in a parallel manner. The microfluidic device is fabricated using multilayer soft lithography technology, and consists of a control layer and a deformable flow channel. Deflections of the PDMS membrane above the main microfluidic flow channels and trapping chamber array are independently regulated pneumatically by two sets of integrated microfluidic valves. We successfully compress and aspirate the double emulsions, which result in transient increase and permanent decrease in oil thickness, respectively. Finally, we demonstrate the influx of calcium ions as a response of our mechanically activated artificial cell through thinning of oil. The development of a microfluidic device to mechanically activate artificial cells creates new opportunities in force-activated synthetic biology.

Dynamical freeze-out criterion in a hydrodynamical description of Au + Au collisions at √{sNN}=200 GeV and Pb + Pb collisions at √{sNN}=2760 GeV

NASA Astrophysics Data System (ADS)

Ahmad, Saeed; Holopainen, Hannu; Huovinen, Pasi

2017-05-01

In hydrodynamical modeling of ultrarelativistic heavy-ion collisions, the freeze-out is typically assumed to take place at a surface of constant temperature or energy density. A more physical approach is to assume that freeze-out takes place at a surface of constant Knudsen number. We evaluate the Knudsen number as a ratio of the expansion rate of the system to the pion-scattering rate and apply the constant Knudsen number freeze-out criterion to the ideal hydrodynamical description of heavy-ion collisions at the Relativistic Heavy Ion Collider at BNL (√{sNN}=200 GeV) and the Large Hadron Collider (√{sNN}=2760 GeV) energies. We see that once the numerical values of freeze-out temperature and freeze-out Knudsen number are chosen to produce similar pT distributions, the elliptic and triangular anisotropies are similar too, in both event-by-event and averaged initial state calculations.

[Veterinary double-monsters historically viewed].

PubMed

Baljet, B; Heijke, G C

1997-01-01

A large number of duplication monstrosities have been observed in cattle, sheep, pigs, horses, goats, cats and dogs, ever since the publication of the famous woodcut of a swine double monster by J. S. Brant in Basel in 1496, better known as the "wunderbare Sau von Landser im Elsass". Albrecht Dürer also made a woodcut of this double monster in front of the village Landser in 1496. A picture of a deer double monster was published in 1603 by Heinrich Ulrich in Germany. In the monograph De monstrorum causis, natura et differentiis ..., published by the Italian Fortunius Licetus in 1616 pictures of double monsters being half man half dog are found. These fantasy figures have been popular for a long time and were supposed to be really in existence. Apart from these fantasy figures many pictures are known from real veterinary double monsters. U. Aldrovandus described in 1642 in his Monstrorum historia, besides many fantasy figures, also real human and veterinary double monsters and he gave also good pictures of them. In the 19th century examples of veterinary duplication monstrosities were published by I. Geoffroy Saint-Hilaire (1832-37), E. F. Gurlt (1832), W. Vrolik (1840) and C. Taruffi (1881); they proposed also concepts concerning the etiology. In the second volume of his famous handbook of teratology (1907), E. Schwalbe described many veterinary double monsters and discussed the theories of the genesis of congenital malformations. Various theories concerning the genesis of double monsters have been given since Aristotle (384-322 B.C.). ...

Double photoionization of atoms

NASA Astrophysics Data System (ADS)

Wiedenhoeft, Marco

2003-10-01

Double photoionization studies of atoms and molecules are new state-of-the-art studies providing a deeper knowledge of multi-electron excitations. This type of work advances the understanding of many-body problems. Double photoionization of atoms is of great interest to learn about electron-electron correlation and relaxation effects in atoms and molecules. In order to study double photoionization processes, a new electron-electron coincidence apparatus was built to carry out the measurements. I will present the apparatus I built as well as the results of the measurement of the triply-differential-cross-section (TDCS) for the predicted interference and Post-Collision-Interaction (PCI) effects in the Xenon N5O2,3 O2,3 Auger decay after 4d5/2 photoionization. Furthermore I present measurements for direct double photoionization of Helium at various photon energies.