Ultraviolet-B radiation causes an upregulation of survivin in human keratinocytes and mouse skin

Understanding of the mechanism of ultraviolet (UV)-mediated cutaneous damages is far from complete. The cancer-specific expression of Survivin, a member of the inhibitor of apoptosis family of proteins, coupled with its importance in inhibiting cell death and in regulating cell division, makes it a target for cancer treatment. This study was designed to investigate the modulation of Survivin during UV response, both in vitro and in vivo. We used UV-B-mediated damages in normal human epidermal keratinocytes (NHEK) cells as an in vitro model and SKH-1 hairless mouse model for the in vivo studies. For in vitro studies, NHEK were treated with UV-B and samples were processed at 5, 15, 30 min, 1, 3, 6, 12 and 24 h after treatment. Our data demonstrated that UV-B exposure (50 mJ/cm2) to NHEK resulted in a significant upregulation in Survivin messenger RNA (mRNA) and protein levels. We also observed that UV-B exposure to NHEK resulted in significant (1) decrease in Smac/DIABLO and (2) increase in p53. For in vivo studies, the SKH-1 hairless mice were subjected to a single exposure of UV-B (180 mJ/cm2), and samples were processed at 3, 6, 12 and 24 h after UV-B exposure. UV-B treatment resulted in a significant increase in protein or mRNA levels (or both) of Survivin, phospho-Survivin and p53 and a concomitant decrease in Smac/DIABLO in mouse skin. This study demonstrated, for the first time, the involvement of Survivin (and the associated events) in UV-B response in vitro and in vivo in experimental models regarded to have relevance to human situations.     

Solvent extraction of neptunium(IV) from nitric acid solutions by sulphoxides and their mixtures

Studies have been performed on the liquid-liquid extraction of neptunium from nitric acid solutions by di-n-hexylsulphoxide (DHSO) di-no-octylsulphoxide (DOSO) and di-iso-amylsulphoxide (DISO) and their mixtures over a wide range of conditions. At a given strength of the extractant, extraction of Np(IV) increases initially rapidly with increase in the acid concentration; at high acidities, above 8M HNO₃, the extraction decreases. Under otherwise identical conditions, extraction increases with an increase in the extractant concentration. The species extracted would appear to be Np(NO₃)₄·2(R₂SO). A mixture of two extractants extracts more than the sum of the extractions due to the individual components at concentrations corresponding to those of the mixture. After loading the organic phase with uranium(VI), extractability of Np(IV) becomes considerably lower. The diminution in extraction with increase in temperature is small. A comparison of the extraction behaviour of Np(IV) with those of Pu(IV), U(VI) and some associated fission products has been made.     

Reactions of guanine with methyl chloride and methyl bromide: O6‐methylation versus charge transfer complex formation

Density functional theory (DFT) at the B3LYP/6‐31+G* and B3LYP/AUG‐cc‐pVDZ levels was employed to study O6‐methylation of guanine due to its reactions with methyl chloride and methyl bromide and to obtain explanation as to why the methyl halides cause genotoxicity and possess mutagenic and carcinogenic properties. Geometries of the various isolated species involved in the reactions, reactant complexes (RCs), and product complexes (PCs) were optimized in gas phase. Transition states connecting the reactant complexes with the product complexes were also optimized in gas phase at the same levels of theory. The reactant complexes, product complexes, and transition states were solvated in aqueous media using the polarizable continuum model (PCM) of the self‐consistent reaction field theory. Zero‐point energy (ZPE) correction to total energy and the corresponding thermal energy correction to enthalpy were made in each case. The reactant complexes of the keto form of guanine with methyl chloride and methyl bromide in water are appreciably more stable than the corresponding complexes involving the enol form of guanine. The nature of binding in the product complexes was found to be of the charge transfer type (O6mG⁺ · X^?, X?Cl, Br). Binding of HCl, HBr, and H₂O molecules to the PCs obtained with the keto form of guanine did not alter the positions of the halide anions in the PCs, and the charge transfer character of the PCs was also not modified due to this binding. Further, the complexes obtained due to the binding of HCl, HBr, and H₂O molecules to the PCs had greater stability than the isolated PCs. The reaction barriers involved in the formation of PCs were found to be quite high (～50 kcal/mol). Mechanisms of genotoxicity, mutagenesis and carcinogenesis caused by the methyl halides appear to involve charge transfer‐type complex formation. Thus the mechanisms of these processes involving the methyl halides appear to be quite different from those that involve the other strongly carcinogenic methylating agents. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Application of generalized linear filters in data analysis

It is shown that a useful generalized linear filterW can be constructed from experimental data. The data are divided into many experiments and this ensemble is used to calculate the autocorrelation functions which appear inW. In turn, from this filter one determines a Hamiltonian . The eigenvectors and eigenvalues of this Hamiltonian are evaluated. For a good experiment there is one small eigenvalue, and the rest are 1. TheW so determined usefully reduces the noise in a new data set. The presence of two or more small eigenvalues indicates that the experimental data contains more than a single signal. The action ofW on selected members of the ensemble, and/or new data sets, extracts the different signals with, again, a useful noise reduction. Both computer simulations and real positron annihilation data are used to illustrate these development.This paper is dedicated to Philippe Choquard on the occasion of this 65th birthday.     

Novel symmetries in the modified version of two dimensional Proca theory

The European Physical Journal C - We present a study of the expected precision of the top quark mass determination, measured at a linear e + e − collider based on CLIC technology....     

Investigation of W/O microemulsion droplets by contrast variation light scattering

Dynamic and static light scattering experiments have been performed at various molar ratios (γ) of water to AOT and temperatures on water-in-oil (W/O) microemulsions dispersed in n-heptane, n-octane, and n-nonane. Size and shape fluctuations of microemulsion droplets are determined with very high precision because polydispersity influences the characteristic features of scattering data as well as the hydrodynamic radius withγ. Self-consistent interpretation of dynamic and static light scattering data using optical properties and packing consideration on the basis of the layered sphere model are obtained. The estimated extent of polydispersity index of 17% is found, whereas the polydispersity is independent of the alkane types. The geometrical parameters, e.g., hydrodynamic radius, area per head group of the surfactant molecule and thickness of the surfactant layer of microemulsion droplets are also estimated and compared in three different n-alkane types. The best interpretation of the temperature dependence of data has shown a transition from spherical droplets to ellipsoid aggregates with increasing temperature. Axial ratio increases with increase of temperature and the longer the alkane the larger is the axial ratio. The parameters describing the polydispersity and shape change are in agreement with theoretical and experimental results found in the literature     

A comparative study of PFP and BAB models in predicting the excess thermo-acoustical and its allied properties of liquid ternary mixtures at 298.15 K

Densities and speed of sound were measured for six binaries and three ternary liquid systems. Excess acoustical and its allied properties like excess internal pressure, excess thermal pressure coefficient, excess pseudo-Gruneisen parameter, excess speed of sound and excess ultrasonic impendence, were evaluated with the help of perspective of two liquid models i.e. Prigogine–Flory–Patterson (PFP) and Bertrand–Acree–Bruchfield (BAB) at 298.15 K over a wide range of composition. The results so obtained from two liquid models are very much comparable and are in good agreement. A molecular interaction study has also been made successfully in the light of these excess acoustical properties.     

A new approach for improving ballistic performance of composite armor

An experimental investigation of the ballistic performance of composite armor with geometric modifications was carried out. The armor was simulated using polymeric materials. Four different geometric modifications were incorporated into the front plate of the armor, and two different adhesives were considered in this study. High-speed photography was employed to observe the real-time evolution of impact damage and to obtain the projectile penetration history. The nature and extent of damage for each modification and adhesive was estimated by postmortem inspection of the impacted armor and was compared to that obtained in unmodified armor of equal weight. The results of the study indicate that the geometric modifications after the nature and extent of damage significantly compared to conventional composite armor. The strong adhesive causes tearing of the back plate, whereas the compliant adhesive results in extensive delamination without any back plate damage. The modifications assist in spreading the damage laterally away from the impact site, thus distributing the load onto a larger area of the back plate. Calculations using a one-dimensional theoretical model also conclude that geometrical modifications improve the ballistic performance of the armor.