823 research outputs found
Expression and distribution of the glucocorticoid receptor DlGR1 in the teleost Dicentrarchus labrax brain.
Cortisol is the main corticosteroid secreted by the interrenal cells of the head kidney and it exerts a role in mantaining the omeostatic status in fish. In teleosts its effects are mediated through intracellular receptors expressed in several tissues, that are ligand-dependent transcription factors by binding to specific tissue DNA sequences. In Dicentrarchus labrax we previously cloned and sequenced a glucocorticoid receptor, DlGR1, isolated from leukocytes of peritoneal cavity. In this work we showed mRNA expression and tissue immunohistochemical localization of brain DlGR1 by in situ hybridization assays, with a riboprobe with DlGR1 cDNA trascriptional activation domain, and by immunohistochemical methods, using a specific antibody for a selected sequence of the receptor tran- scriptional domain. The mRNA and the protein are expressed in pyramidal cells of the optic lobe and in the small globular neurons of the diencephalon
Metric tensor as the dynamical variable for variable cell-shape molecular dynamics
We propose a new variable cell-shape molecular dynamics algorithm where the
dynamical variables associated with the cell are the six independent dot
products between the vectors defining the cell instead of the nine cartesian
components of those vectors. Our choice of the metric tensor as the dynamical
variable automatically eliminates the cell orientation from the dynamics.
Furthermore, choosing for the cell kinetic energy a simple scalar that is
quadratic in the time derivatives of the metric tensor, makes the dynamics
invariant with respect to the choice of the simulation cell edges. Choosing the
densitary character of that scalar allows us to have a dynamics that obeys the
virial theorem. We derive the equations of motion for the two conditions of
constant external pressure and constant thermodynamic tension. We also show
that using the metric as variable is convenient for structural optimization
under those two conditions. We use simulations for Ar with Lennard-Jones
parameters and for Si with forces and stresses calculated from first-principles
of density functional theory to illustrate the applications of the method.Comment: 10 pages + 6 figures, Latex, to be published in Physical Review
An efficient k.p method for calculation of total energy and electronic density of states
An efficient method for calculating the electronic structure in large systems
with a fully converged BZ sampling is presented. The method is based on a
k.p-like approximation developed in the framework of the density functional
perturbation theory. The reliability and efficiency of the method are
demostrated in test calculations on Ar and Si supercells
Elastic Constants of Quantum Solids by Path Integral Simulations
Two methods are proposed to evaluate the second-order elastic constants of
quantum mechanically treated solids. One method is based on path-integral
simulations in the (NVT) ensemble using an estimator for elastic constants. The
other method is based on simulations in the (NpT) ensemble exploiting the
relationship between strain fluctuations and elastic constants. The strengths
and weaknesses of the methods are discussed thoroughly. We show how one can
reduce statistical and systematic errors associated with so-called primitive
estimators. The methods are then applied to solid argon at atmospheric
pressures and solid helium 3 (hcp, fcc, and bcc) under varying pressures. Good
agreement with available experimental data on elastic constants is found for
helium 3. Predictions are made for the thermal expectation value of the kinetic
energy of solid helium 3.Comment: 9 pages doublecolumn, 6 figures, submitted to PR
Defect-unbinding transitions and inherent structures in two dimensions
We present a large-scale (36000-particle) computational study of the
"inherent structures" (IS) associated with equilibrium, two-dimensional,
one-component Lennard-Jones systems. Our results provide strong support both
for the inherent-structures theory of classical fluids, and for the KTHNY
theory of two-stage melting in two dimensions. This support comes from the
observation of three qualitatively distinct "phases" of inherent structures: a
crystal, a "hexatic glass", and a "liquid glass". We also directly observe, in
the IS, analogs of the two defect-unbinding transitions (respectively, of
dislocations, and disclinations) believed to mediate the two equilibrium phase
transitions. Each transition shows up in the inherent structures---although the
free disclinations in the "liquid glass" are embedded in a percolating network
of grain boundaries. The bond-orientational correlation functions of the
inherent structures show the same progressive loss of order as do the three
equilibrium phases: long-range to quasi-long-range to short-range.Comment: RevTeX, 8 pages, 15 figure
Gluon Propagator in the Infrared Region
The gluon propagator is calculated in quenched QCD for two different lattice
sizes (16^3x48 and 32^3x64) at beta=6.0. The volume dependence of the
propagator in Landau gauge is studied. The smaller lattice is instrumental in
revealing finite volume and anisotropic lattice artefacts. Methods for
minimising these artefacts are developed and applied to the larger lattice
data. New structure seen in the infrared region survives these conservative
cuts to the lattice data. This structure serves to rule out a number of models
that have appeared in the literature. A fit to a simple analytical form
capturing the momentum dependence of the nonperturbative gluon propagator is
also reported.Comment: 13 pages, 9 figures, using RevTeX. Submitted to Phys. Rev. D. This
and related papers can also be obtained from
http://www.physics.adelaide.edu.au/~jskuller/papers
Cycloastragenol as an exogenous enhancer of chondrogenic differentiation of human adipose-derived mesenchymal stem cells. A morphological study
Stem cell therapy and tissue engineering represent a promising approach for cartilage regeneration. However, they present limits in terms of mechanical properties and premature de-differentiation of engineered cartilage. Cycloastragenol (CAG), a triterpenoid saponin compound and a hydrolysis product of the main ingredient in Astragalus membranaceous, has been explored for cartilage regeneration. The aim of this study was to investigate CAG's ability to promote cell proliferation, maintain cells in their stable active phenotype, and support the production of cartilaginous extracellular matrix (ECM) in human adipose-derived mesenchymal stem cells (hAMSCs) in up to 28 days of three-dimensional (3D) chondrogenic culture. The hAMSC pellets were cultured in chondrogenic medium (CM) and in CM supplemented with CAG (CAG-CM) for 7, 14, 21, and 28 days. At each time-point, the pellets were harvested for histological (hematoxylin and eosin (H&E)), histochemical (Alcian-Blue) and immunohistochemical analysis (Type I, II, and X collagen, aggrecan, SOX9, lubricin). After excluding CAG's cytotoxicity (MTT Assay), improved cell condensation, higher glycosaminoglycans (sGAG) content, and increased cell proliferation have been detected in CAG-CM pellets until 28 days of culture. Overall, CAG improved the chondrogenic differentiation of hAMSCs, maintaining stable the active chondrocyte phenotype in up to 28 days of 3D in vitro chondrogenic culture. It is proposed that CAG might have a beneficial impact on cartilage regeneration approaches
Exploring the conformational dynamics of alanine dipeptide in solution subjected to an external electric field: A nonequilibrium molecular dynamics simulation
In this paper, we investigate the conformational dynamics of alanine
dipeptide under an external electric field by nonequilibrium molecular dynamics
simulation. We consider the case of a constant and of an oscillatory field. In
this context we propose a procedure to implement the temperature control, which
removes the irrelevant thermal effects of the field. For the constant field
different time-scales are identified in the conformational, dipole moment, and
orientational dynamics. Moreover, we prove that the solvent structure only
marginally changes when the external field is switched on. In the case of
oscillatory field, the conformational changes are shown to be as strong as in
the previous case, and non-trivial nonequilibrium circular paths in the
conformation space are revealed by calculating the integrated net probability
fluxes.Comment: 23 pages, 12 figure
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