655 research outputs found
ASCA Observations of Two Ultra-Luminous Compact X-Ray Sources in the Edge-on Spiral Galaxy NGC 4565
The edge-on spiral galaxy NGC 4565 was observed for 35 ks with ASCA in
the 0.5-10 keV energy band. The X-ray emission was dominated by two bright
sources, which can be identified with two point-like X-ray sources seen in the
ROSAT HRI image. The observed 0.5-10 keV fluxes of these sources, and , % % imply bolometric
luminosities of and ,
respectively. They exhibit similar spectra, which can be explained by emission
from optically thick accretion disks with the inner disk temperature of 1.4-1.6
keV. One of them, coincident in position with the nucleus, shows too low
absorption to be the active nucleus seen through the galaxy disk. Their spectra
and high luminosities suggest that they are both mass accreting black hole
binaries. However the black-hole mass required by the Eddington limit is rather
high (), and the observed disk temperature is too high to be
compatible with the high black-hole mass. Several attempts are made to solve
these problesms.Comment: 20page
Polyamine depletion induces G1 and S phase arrest in human retinoblastoma Y79 cells
<p>Abstract</p> <p>Background</p> <p>Polyamines and ornithine decarboxylase (ODC) are essential for cell proliferation. DL-α-difluoromethylornithine (DFMO), a synthetic inhibitor of ODC, induces G<sub>1 </sub>arrest through dephosphorylation of retinoblastoma protein (pRb). The effect of DFMO on cell growth of pRb deficient cells is not known. We examined the effects of DFMO on pRb deficient human retinoblastoma Y79 cell proliferation and its molecular mechanism.</p> <p>Methods</p> <p>Using cultured Y79 cells, the effects of DFMO were studied by using polyamine analysis, western blot, gel shift, FACS and promoter analysis.</p> <p>Results</p> <p>DFMO suppressed the proliferation of Y79 cells, which accumulated in the G1 and S phase. DFMO induced p27/Kip1 protein expression, p107 dephosphorylation and accumulation of p107/E2F-4 complex in Y79 cells.</p> <p>Conclusion</p> <p>These results indicate that p107 dephosphorylation and accumulation of p107/E2F-4 complex is involved in G<sub>1 </sub>and S phase arrest of DFMO treated Y79 cells.</p
Role of KIT-Positive Interstitial Cells of Cajal in the Urinary Bladder and Possible Therapeutic Target for Overactive Bladder
In the gastrointestinal tract, interstitial cells of Cajal (ICCs) act as pacemaker cells to generate slow wave activity. Interstitial cells that resemble ICCs in the gastrointestinal tract have been identified by their morphological characteristics in the bladder. KIT is used as an identification marker of ICCs. ICCs in the bladder may be involved in signal transmission between smooth muscle bundles, from efferent nerves to smooth muscles, and from the urothelium to afferent nerves. Recent research has suggested that not only the disturbance of spontaneous contractility caused by altered detrusor ICC signal transduction between nerves and smooth muscle cells but also the disturbance of signal transduction between urothelial cells and sensory nerves via suburothelial ICC may induce overactive bladder (OAB). Recent reports have suggested that KIT is not only a detection marker of these cells, but also may play a crucial role in the control of bladder function. Research into the effect of a c-kit receptor inhibitor, imatinib mesylate, on bladder function implies that KIT-positive ICCs may be therapeutic target cells to reduce bladder overactivity and that the blockage of c-kit receptor may offer a new therapeutic strategy for OAB treatment, although further study will be needed
Reducing nonideal to ideal coupling in random matrix description of chaotic scattering: Application to the time-delay problem
We write explicitly a transformation of the scattering phases reducing the
problem of quantum chaotic scattering for systems with M statistically
equivalent channels at nonideal coupling to that for ideal coupling. Unfolding
the phases by their local density leads to universality of their local
fluctuations for large M. A relation between the partial time delays and
diagonal matrix elements of the Wigner-Smith matrix is revealed for ideal
coupling. This helped us in deriving the joint probability distribution of
partial time delays and the distribution of the Wigner time delay.Comment: 4 pages, revtex, no figures; published versio
Effect of antibiotic therapy on the inflammatory responses during streptococcal pneumonia in emphysematous mice
Background and objective: Bacterial infection is one of the most important causes of acute exacerbation of respiratory failure in patients with chronic obstructive pulmonary disease (COPD). There were few studies evaluating the effects of early intervention by antibiotic on respiratory bacterial infection in COPD subjects. We investigated the effect of early intervention by respiratory quinolone antibiotic on the systemic inflammatory responses induced by streptococcal pneumonia using a mouse model of experimental emphysema.
Methods: Experimental pulmonary emphysema was developed by a single intratracheal instillation of porcine pancreatic elastase in ICR mice. Three weeks later, lethal doses of Streptococcus pneumoniae were intratracheally inoculated, followed by oral administration of 50 mg/kg body weight of Grepafloxacin (GPFX) every day from a day after tracheal inoculation.
Results: While all emphysematous mice without GPFX treatment died within 8 days, all emphysematous mice with GPFX treatment survived. Seventy two hrs after infection, serum levels of tumor necrosis factor alpha, chemokine (C-X-C motif) ligand 1, and CXCL2 (Macrophage inflammatory protein-2) in emphysematous mice with antibiotic therapy were significantly lower than those without therapy.
Conclusions: Thus, the early intervention using a respiratory quinolone antibiotic prevents emphysematous mice with pneumonia from severe systemic inflammation, and rescues these mice from death. These results suggest that early intervention using a respiratory quinolone may improve the outcome of the exacerbated COPD patients
AC resistivity of d-wave ceramic superconductors
We model d-wave ceramic superconductors with a three-dimensional lattice of
randomly distributed Josephson junctions with finite self-inductance. The
linear and nonlinear ac resistivity of the d-wave ceramic superconductors is
obtained as function of temperature by solving the corresponding Langevin
dynamical equations. We find that the linear ac resistivity remains finite at
the temperature where the third harmonics of resistivity has a peak. The
current amplitude dependence of the nonlinear resistivity at the peak position
is found to be a power law. These results agree qualitatively with experiments.
We also show that the peak of the nonlinear resistivity is related to the onset
of the paramagnetic Meissner effect which occurs at the crossover temperature
, which is above the chiral glass transition temperature .Comment: 7 eps figures, Phys. Rev. B (in press
Discovery of a new dwarf nova, TSS J022216.4+412259.9: WZ Sge-type dwarf novae breaking the shortest superhump period record
We report on the time-resolved CCD photometry of a newly discovered variable
star, TSS J022216.4+412259.9 during the outburst in 2005 November-December
brightening. The obtained light curves unambiguously showed 0.2-0.3 mag
modulations, which we confirmed to be the superhump observed among SU UMa-type
dwarf novae. We also performed a period search for the data obtained during the
outburst plateau phase, and revealed the existence of the two periodicities:
0.054868(98) days for the first two nights and 0.055544(26) days for the
following plateau phase. This bi-periodicity is hardly observed in usual SU
UMa-type dwarf novae, but characteristic of WZ Sge-type stars. We undoubtedly
detected a rebrightening in the post-outburst stage, which is typical of
short-period SU UMa-type dwarf novae including WZ Sge-type stars. These
observations suggests that TSS J022216.4+412259.9 may be a new WZ Sge stars
breaking the shortest superhump period of 0.05648 days for V592 Her among this
class with a known superhump period so far.Comment: 5 pages, 6 figures, accepted for PASJ lette
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