Neuregulin 1-Beta cytoprotective role in AML 12 mouse hepatocytes exposed to pentachlorophenol.

Neuregulins are a family of growth factor domain proteins that are structurally related to the epidermal growth factor. Accumulating evidence has shown that neuregulins have cyto- and neuroprotective properties in various cell types. In particular, the neuregulin-1 Beta (NRG1-Beta) isoform is well documented for its antiinflammatory properties in rat brain after acute stroke episodes. Pentachlorophenol (PCP) is an organochlorine compound that has been widely used as a biocide in several industrial, agricultural, and domestic applications. Previous investigations from our laboratory have demonstrated that PCP exerts both cytotoxic and mitogenic effects in human liver carcinoma (HepG2) cells, primary catfish hepatocytes and AML 12 mouse hepatocytes. We have also shown that in HepG2 cells, PCP has the ability to induce stress genes that may play a role in the molecular events leading to toxicity and tumorigenesis. In the present study, we hypothesize that NRG1-Beta will exert its cytoprotective effects in PCP-treated AML 12 mouse hepatocytes by its ability to suppress the toxic effects of PCP. To test this hypothesis, we performed the MTT-cell respiration assay to assess cell viability, and Western-blot analysis to assess stress-related proteins as a consequence of PCP exposure. Data obtained from 48 h-viability studies demonstrated a biphasic response; showing a dose-dependent increase in cell viability within the range of 0 to 3.87 microg/mL, and a gradual decrease within the concentration range of 7.75 to 31.0 microg/mL in concomitant treatments of NRG1-Beta+PCP and PCP. Cell viability percentages indicated that NRG1-Beta+PCPtreated cells were not significantly impaired, while PCP-treated cells were appreciably affected; suggesting that NRG1-Beta has the ability to suppress the toxic effects of PCP. Western Blot analysis demonstrated the potential of PCP to induce oxidative stress and inflammatory response (c-fos), growth arrest and DNA damage (GADD153), proteotoxic effects (HSP70), cell cycle arrest as consequence of DNA damage (p53), mitogenic response (cyclin- D1), and apoptosis (caspase-3). NRG1-Beta exposure attenuated stress-related protein expression in PCP-treated AML 12 mouse hepatocytes. Here we provide clear evidence that NRG1-Beta exerts cytoprotective effects in AML 12 mouse hepatocytes exposed to PCP

Quick actuating closure and handling system

A quick activating closure and handling system, which utilizes conical sections for locking, was developed to allow quick access to the combustor internal components of the 8 ft High Temperature Tunnel. These critical components include the existing methane spraybar, a transpiration cooled nozzle and the new liquid oxygen (LOX) injection system housed within the combustor. A substantial cost savings will be realized once the mechanism is installed since it will substantially reduce the access time and increase the time available for conducting wind tunnel tests. A need exists for more frequent inspections when the wind tunnel operates at the more severe conditions generated by using LOX in the combustor. A loads analysis and a structural (finite element) analysis were conducted to verify that the new closure system is compatible with the existing pressure shell. In addition, strain gages were placed on the pressure vessel to verify how the pressure shell reacts to transient pressure loads. A scale model of the new closure system was built to verify the operation of the conical sections in the locking mechanisms

Anisotropic states of two-dimensional electrons in high magnetic fields

We study the collective states formed by two-dimensional electrons in Landau levels of index $n\ge 2$ near half-filling. By numerically solving the self-consistent Hartree-Fock (HF) equations for a set of oblique two-dimensional lattices, we find that the stripe state is an anisotropic Wigner crystal (AWC), and determine its precise structure for varying values of the filling factor. Calculating the elastic energy, we find that the shear modulus of the AWC is small but finite (nonzero) within the HF approximation. This implies, in particular, that the long-wavelength magnetophonon mode in the stripe state vanishes like $q^{3/2}$ as in an ordinary Wigner crystal, and not like $q^{5/2}$ as was found in previous studies where the energy of shear deformations was neglected.Comment: minor corrections; 5 pages, 4 figures; version to be published in Physical Review Letter

Nucleation and Growth of the Superconducting Phase in the Presence of a Current

We study the localized stationary solutions of the one-dimensional time-dependent Ginzburg-Landau equations in the presence of a current. These threshold perturbations separate undercritical perturbations which return to the normal phase from overcritical perturbations which lead to the superconducting phase. Careful numerical work in the small-current limit shows that the amplitude of these solutions is exponentially small in the current; we provide an approximate analysis which captures this behavior. As the current is increased toward the stall current J*, the width of these solutions diverges resulting in widely separated normal-superconducting interfaces. We map out numerically the dependence of J* on u (a parameter characterizing the material) and use asymptotic analysis to derive the behaviors for large u (J* ~ u^-1/4) and small u (J -> J_c, the critical deparing current), which agree with the numerical work in these regimes. For currents other than J* the interface moves, and in this case we study the interface velocity as a function of u and J. We find that the velocities are bounded both as J -> 0 and as J -> J_c, contrary to previous claims.Comment: 13 pages, 10 figures, Revte

Deployable-erectable trade study for space station truss structures

The results of a trade study on truss structures for constructing the space station are presented. Although this study was conducted for the reference gravity gradient space station, the results are generally applicable to other configurations. The four truss approaches for constructing the space station considered in this paper were the 9 foot single fold deployable, the 15 foot erectable, the 10 foot double fold tetrahedral, and the 15 foot PACTRUSS. The primary rational for considering a 9 foot single-fold deployable truss (9 foot is the largest uncollapsed cross-section that will fit in the Shuttle cargo bay) is that of ease of initial on-orbit construction and preintegration of utility lines and subsystems. The primary rational for considering the 15 foot erectable truss is that the truss bay size will accommodate Shuttle size payloads and growth of the initial station in any dimension is a simple extension of the initial construction process. The primary rational for considering the double-fold 10 foot tetrahedral truss is that a relatively large amount of truss structure can be deployed from a single Shuttle flight to provide a large number of nodal attachments which present a pegboard for attaching a wide variety of payloads. The 15 foot double-fold PACTRUSS was developed to incorporate the best features of the erectable truss and the tetrahedral truss

Charge Transport in the Dense Two-Dimensional Coulomb Gas

The dynamics of a globally neutral system of diffusing Coulomb charges in two dimensions, driven by an applied electric field, is studied in a wide temperature range around the Berezinskii-Kosterlitz-Thouless transition. I argue that the commonly accepted ``free particle drift'' mechanism of charge transport in this system is limited to relatively low particle densities. For higher densities, I propose a modified picture involving collective ``partner transfer'' between bound pairs. The new picture provides a natural explanation for recent experimental and numerical findings which deviate from standard theory. It also clarifies the origin of dynamical scaling in this context.Comment: 4 pages, RevTeX, 2 eps figures included; some typos corrected, final version to be published in Phys. Rev. Let

Luttinger Liquid in the Core of Screw Dislocation in Helium-4

On the basis of first-principle Monte Carlo simulations we find that the screw dislocation along the hexagonal axis of an hcp He4 crystal features a superfluid core. This is the first example of a regular quasi-one-dimensional supersolid, and one of the cleanest cases of a regular Luttinger-liquid system. In contrast, the same type of screw dislocation in solid Hydrogen is insulating.Comment: replaced with revised versio

Hall-Effect Sign Anomaly and Small-Polaronic Conduction in (La_{1-x}Gd_x)_{0.67}Ca_{0.33}MnO_3

The Hall coefficient of Gd-doped La_{2/3}Ca_{1/3}MnO_3 exhibits Arrhenius behavior over a temperature range from 2T_c to 4T_c, with an activation energy very close to 2/3 that of the electrical conductivity. Although both the doping level and thermoelectric coefficient indicate hole-like conduction, the Hall coefficient is electron-like. This unusual result provides strong evidence in favor of small-polaronic conduction in the paramagnetic regime of the manganites.Comment: 11 pages, 4 figures, uses revtex.st

Dynamics of a Vortex in Two-Dimensional Superfluid He3-A: Force Caused by the l-Texture

Based on the Landau-Ginzburg Lagrangian, the dynamics of a vortex is studied for superfluid He3-A characterized by the l-texture. The resultant equation of motion for a vortex leads to the Magnus-type force caused by the l-texture. The force is explicitly written in terms of the mapping degree from the compactified 2-dimensional plane to the space of l-vector, which reflects the quantitative differences of vortex configurations, especially the Mermin-Ho and Anderson-Toulouse vortices. The formulation is applied to anisotropic superconductors in which the Hall current is shown to incorporate changes between vortex configurations.Comment: 4 pages, RevTex(twocolumn