478 research outputs found
Social Media and Financial Market (<Special Issue>Theory and Application of Econometrics)
textabstractAll members of the steroid hormone receptor family are phosphoproteins. Additional phosphorylation occurs in the presence of hormone. This hormone-induced phosphorylation, which is 2- to 7-fold more than the basal phosphorylation, is a rapid process. All steroid receptors are phosphorylated at more than one single site. Most phosphorylation sites are located in the N-terminal domain, and phosphorylation occurs mainly on serine residues. Phosphorylation on threonine residues occurs in only a few cases. Phosphorylation on tyrosine residues has been found only for the estrogen receptor. Six different protein kinases are possibly involved in steroid receptor phosphorylation (estrogen receptor kinase; protein kinase A; protein kinase C; casein kinase II; DNA-dependent kinase; Ser-Pro kinases). Steroid receptor phosphorylation has been directly implicated in: activation of hormone binding, nuclear import of steroid receptors, modulation of binding to hormone response elements, and consequently in transcription activation
Feasibility of a Unitary Quantum Dynamics in the Gowdy Cosmological Model
It has been pointed out that it is impossible to obtain a unitary
implementation of the dynamics for the polarized Gowdy cosmologies in
an otherwise satisfactory, nonperturbative canonical quantization proposed for
these spacetimes. By introducing suitable techniques to deal with
deparametrized models in cosmology that possess an explicit time dependence (as
it is the case for the toroidal Gowdy model), we present in this paper a
detailed analysis about the roots of this failure of unitarity. We investigate
the impediments to a unitary implementation of the evolution by considering
modifications to the dynamics. These modifications may be regarded as
perturbations. We show in a precise manner why and where unitary
implementability fails in our system, and prove that the obstructions are
extremely sensitive to modifications in the Hamiltonian that dictates the time
evolution of the symmetry-reduced model. We are able to characterize to a
certain extent how far the model is from unitarity. Moreover, we demonstrate
that the dynamics can actually be approximated as much as one wants by means of
unitary transformations.Comment: 12 pages, version accepted for publication in Physical Review
Cellular uptake of steroids
The general concept concerning mechanism of steroid
hormone action includes several steps at the molecular level
about which very little is known. ·For several steroid responsive
tissues it has been shown, that the steroid molecule
after entering its target cell, becomes immediately bound by
a "cytoplasmic receptor" which transfers the steroid into the
nucleus. This translocation step is temperature dependent.
Simultaneously the receptor part of the complex is transformed
into a smaller subunit, the "nuclear receptor". In the
nucleus the steroid receptor complex becomes attached to an
acidic non histone protein, the "nuclear acceptor" site, and
provokes an increase in RNA polymerase activity resulting in
new RNA synthesis followed by increased protein synthesis
Delay of phagosome maturation by a mycobacterial lipid is reversed by nitric oxide.
Mycobacterium tuberculosis is a facultative intracellular pathogen that inhibits phagosome maturation in macrophages thereby securing survival and growth. Mycobacteria reside in an early endocytic compartment of near-neutral pH where they upregulate production of complex glycolipids such as trehalose dimycolate. Here, we report that trehalose dimycolate coated onto beads increased the bead retention in early phagosomes, i.e. at a similar stage as viable mycobacteria. Thus, a single mycobacterial lipid sufficed to divert phagosome maturation and likely contributes to mycobacterial survival in macrophages. Previous studies showed that activated macrophages promote maturation of mycobacterial phagosomes and eliminate mycobacteria through bactericidal effectors including nitric oxide generated by inducible nitric-oxide synthase. We show that deceleration of bead phagosome maturation by trehalose dimycolate was abolished in immune-activated wild type, but not in activated nitric-oxide synthase-deficient macrophages, nor when hydroxyl groups of trehalose dimycolate were chemically modified by reactive nitrogen intermediates. Thus, specific host defence effectors of activated macrophages directly target a specific virulence function of mycobacteria
On the rapid TeV flaring activity of Markarian 501
Aims: We investigate the one-zone SSC model of TeV blazars in the presence of
electron acceleration. In this picture electrons reach a maximum energy where
acceleration saturates from a combination of synchrotron and inverse Compton
scattering losses. Methods: We solve the spatially averaged kinetic equations
which describe the simultaneous evolution of particles and photons, obtaining
the multi-wavelength spectrum as a function of time. Results: We apply the
model to the rapid flare of Mrk 501 of July 9, 2005 as this was observed by the
MAGIC telescope and obtain the relevant parameters for the pre-flare quasi
steady state and the ones during the flare. We show that a hard lag flare can
be obtained with parameters which lie well within the range already accepted
for this source. Especially the choice of a high value of the Doppler factor
seems to be necessary.Comment: 4 pages, 4 figures, to appear in A&A (Letters
Proteomic analysis of androgen-regulated protein expression in a mouse fetal vas deferens cell line
During sex differentiation, androgens are essential for development of the
male genital tract. The Wolffian duct is an androgen-sensitive target
tissue that develops into the epididymis, vas deferens, and seminal
vesicle. The present study aimed to identify androgen-regulated proteins
that are involved in development of Wolffian duct-derived structures. We
have used male mouse embryos transgenic for temperature-sensitive simian
virus 40 large tumor antigen at 18 d of gestation, to generate
immortalized mouse fetal vas deferens (MFVD) parental and clonal cell
lines. The MFVD parental and clonal cell lines express androgen receptor
protein and show features of Wolffian duct mesenchymal cells. Clonal cell
line MFVD A6 was selected for proteomic analysis and cultured in the
absence or presence of androgens. Subsequently, two-dimensional gel
electrophoresis was performed on total cell lysates. Differentially
expressed proteins were analyzed by matrix-assisted laser
desorption/ionization time-of-flight mass spectrometry and two
androgen-regulated proteins were identified as mElfin and CArG-binding
factor-A (CBF-A). CBF-A and mElfin are known to bind to cytoskeletal
F-actin. Both proteins appeared to be regulated by androgens at the
posttranslational level, possibly involving phosphorylation.
Posttranslational modification of mElfin and CBF-A by androgens may be
associated with a cytoskeletal change that is involved in
androgen-regulated gene expression
Androgen receptor expression in human ovarian and uterine tissue of long term androgen-treated transsexual women
Androgen receptor (AR) modulation in human uteri and ovaries of long term androgen-treated transsexual female patients was investigated. Androgen receptor expression was evaluated immunohistochemically in the ovaries of 11 and the endometria and myometria of six androgen-treated transsexual female patients. This was compared with AR expression in the ovaries and uteri of premenopausal and postmenopausal women not receiving treatment and in 10 ovaries of female patients with polycystic ovarian disease (PCOD). In the normal ovaries germinal epithelium, granulosa cells of antral follicles, corpus luteum, and thecal and stromal cells exhibited moderate AR expression. The more intense and uniform staining of ovarian stroma of female transsexual patients and those of patients with PCOD compared with ovarian stroma of normal controls was most remarkable. This similarity in histology and distribution of ARs supports the hypothesis that PCOD is an androgen-mediated disorder. Immunostaining for ARs was only occasionally detectable in the uteri of premenopausal and postmenopausal women. In contrast, myometrial and endometrial stroma of the uteri of female transsexual patients displayed an intense and diffuse nuclear immunostaining, but glandular epithelia remained unstained. Western blot analysis of the ovaries and uterine myometrial tissue samples from transsexual female patients confirmed the presence of the 110-kd AR molecule. Because the androgen treatment of some transsexual female patients was discontinued 6 weeks before they underwent hysterosalpingo-oophorectomy, our data indicate a stable and persistent androgen-induced up-regulation of AR expression in ovaries
- …