216 research outputs found
Distortion of Magnetic Fields in a Starless Core V: Near-infrared and Submillimeter Polarization in FeSt 1-457
The relationship between submillimeter (submm) dust emission polarization and
near-infrared (NIR) -band polarization produced by dust dichroic extinction
was studied for the cold starless dense core FeSt 1-457. The distribution of
polarization angles (-rotated for submm) and degrees were found to
be very different between at submm and NIR wavelengths. The mean polarization
angles for FeSt 1-457 at submm and NIR wavelengths are and , respectively. The correlation
between and was found to be linear from outermost regions to
relatively dense line of sight of mag, indicating that NIR
polarization reflects overall polarization (magnetic field) structure of the
core at least in this density range. The flat versus
correlations were confirmed, and the polarization efficiency was found to be
comparable to the observational upper limit (Jones 1989). On the other hand, as
reported by Alves et al., submm polarization degrees show clear linearly
decreasing trend against from mag to the densest center
( mag), appearing as "polarization hole" structure. The power
law index for the versus relationship was obtained to be
, indicating that the alignment for the submm sensitive dust is
lost. These very different polarization distributions at submm and NIR
wavelengths suggest that (1) there is different radiation environment at these
wavelengths or (2) submm-sensitive dust is localized or the combination of
them.Comment: Accepted to the Astrophysical Journal (ApJ
Cyclin A2-CDK2 regulates embryonic gene activation in 1-cell mouse embryos
AbstractRecruitment of maternal mRNA in mice appears essential for embryonic gene activation (EGA) that is initiated in the 1-cell stage. The identity of which recruited mRNAs is responsible, however, is not known. We report here that recruitment of cyclin A2 mRNA may be critical for EGA. Cyclin A2 protein accumulates in pronuclei between 6 and 12 h after fertilization, the time when EGA is initiated. This cyclin A2 may be generated from maternally recruited cyclin A2 mRNA because its accumulation was inhibited by 3′-deoxyadenosine, which inhibits mRNA polyadenylation. When CDK2 activity or pronuclear accumulation of cyclin A2 was inhibited with CDK2 inhibitors or by microinjected siRNAs, respectively, DNA replication was not inhibited but the increase of transcriptional activity was prevented. In addition, microinjection of recombinant cyclin A2-CDK2 protein increased transcriptional activity. Cyclin A2-CDK2 is activated following egg activation, because an increase in phosphorylation of retinoblastoma protein was observed using antibodies that recognize site-specific phosphorylation catalyzed by this kinase and treatment with a CDK2 inhibitor or microinjection with cyclin A2 siRNAs prevented the increase in retinoblastoma protein phosphorylation. These results suggest that recruitment of maternal cyclin A2 mRNA following egg activation is linked to EGA
Effects of Extracellular Acidification on Intracellular pH and ATP-Induced Calcium Mobilization in Rabbit Lens Epithelial Cells
Effects of extracellular acidification on intracellular pH (pHi) and ATP-induced calcium mobilization were investigated in rabbit lens epithelial cells. Primary-cultured lens epithelial cells of Japanese white rabbits were used. Intracellular calcium ([Ca2+]i) and pHi were measured by using fluorescent dyes, fura-2 acetoxymethylester (fura-2 AM) and 2',7'-bis (carboxyethyl)-5,6-carboxyfluorescein acetoxymethylester (BCECF AM), respectively. The addition of 10 ?mol/L ATP produced an initial peak followed by a sustained increase in [Ca2+]i in a standard artificial aqueous humor at extracellular pH (pH0) 7.40. The initial peak was abolished by pretreatment with 1 ?mol/L thapsigargin, whereas the sustained increase was attenuated in a Ca2+-free solution or by pretreatment with 100 ?mol/L verapamil. Acidification of the pH0 from 7.40 to 6.80 decreased the pHi from 7.21 to 7.03, and enhanced both the initial peak and sustained increase in [Ca2+]i. These results suggest that acidification of pH0 significantly affects the pHi and modifies the ATP-induced [Ca2+]i transient in rabbit lens epithelial cells
Progression of Renal Dysfunction in Patients with Cardiovascular Disease
It has been established that patients with chronic kidney disease (CKD) suffer from frequent cardiovascular events. On the other hand, recent studies suggest that renal damage tends to worsen in patients with cardiovascular diseases (CVD). Although the mechanisms for the cardiorenal association are unclear, the presence of arteriosclerotic risk factors common to both CVD and CKD is important. In arteriosclerosis, vascular derangement progresses not only in the heart but also in the kidney. In addition, heart failure, cardiac catheterization and hesitation of medical treatments due to renal dysfunction may explain the progression of renal damage. Therefore, the goal of treatments is a total control of arteriosclerotic risk factors. Medication should be selected among agents with protective effects on both heart and kidney. It is important to always consider the presence of CKD for the treatment of the cardiovascular disease and strictly control the risk factors
Blood Flow Changes in the Optic Nerve Head of Albino Rabbits Following Intravenous Administration of Brovincamine Fumarate, an Improver of Cerebral Circulation and Metabolism
Blood flow changes in the optic nerve head of normal, adult albino rabbits following intravenous administration of brovincamine fumarate (BV), an improver of cerebral circulation and metabolism, were investigated employing the hydrogen clearance method. In the BV (0.1 mg/kg)-administered group, the blood flow in the optic nerve head showed a gradual increase immediately after injection and reached a maximal value of 124.2 ± 7.3% against the value before injection at 20 min after injection, followed by a gradual decrease in blood flow. Statistical analysis showed a significant increase (P < 0.05) in blood flow at 10 to 40 min after injection, compared with the value before injection in the BV (0.1 mg/kg)-administered group, but no significant changes in blood flow were observed in either the BV (0.5 mg/kg)-administered group or the control group given no BV throughout the time course. No significant changes in the mean values of the mean blood pressure in the femoral artery, pulse rate, respiratory rate or rectal temperature were observed in any group throughout the experiment. These results indicate the different efficacy of the two doses to the relaxing action of the feeding vessels around the optic nerve head
Distortion of Magnetic Fields in a Starless Core IV: Magnetic Field Scaling on Density and Mass-to-flux Ratio Distribution in FeSt 1-457
In the present study, the magnetic field scaling on density, , was revealed in a single starless core for the first time. The
index of was obtained toward the starless dense core
FeSt 1-457 based on the analysis of the radial distribution of the polarization
angle dispersion of background stars measured at the near-infrared wavelengths.
The result prefers for the case of isotropic contraction, and
the difference of the observed value from is 2.8 sigma. The
distribution of the ratio of mass to magnetic flux was evaluated. FeSt 1-457
was found to be magnetically supercritical near the center (), whereas nearly critical or slightly subcritical at the core boundary
(). Ambipolar-diffusion-regulated star formation models
for the case of moderate magnetic field strength may explain the physical
status of FeSt 1-457. The mass-to-flux ratio distribution for typical dense
cores (critical Bonnor--Ebert sphere with central and
--) was calculated and found to be magnetically
critical/subcritical at the core edge, which indicates that typical dense cores
are embedded in and evolve from magnetically critical/subcritical diffuse
surrounding medium.Comment: Accepted to the Astrophysical Journal (ApJ
Morphological Changes in Patient Lens Epithelial Cells after Intravitreal Silicone Oil Injection
The subject patient (47-year-old male) had received silicone oil injection into the vitreous cavity of his left eye for the treatment of retinal detachment in 1986. Two months later, the silicone oil was removed from the vitreous cavity, as the retina was reattached. Soon after the operation, the lens of the eye gradually became opaque to mature cataract, and his left visual acuity had fallen to hand motion upon his present admission to the hospital. The lens epithelium obtained by anterior capsulotomy during the extracapsular cataract extraction was examined morphologically by transmission electron microscopy. Inside the anterior lens capsule, abnormal epithelial proliferation was observed. The epithelial cells changed their shapes from cuboidal to spindle, accompanied by new basal lamina-like substances around them. The spindle-shaped cells stretched like pseudopodia. The extracellular matrices were abundant and composed of collagen fibers. Fragments and dissolved materials of the fibers were also seen in some specimens. Lipid-like substances and myelin-like structures were often observed in the relatively well preserved cytoplasm. As a result, it is surmised that cataract formation after intravitreal silicone oil injection may be associated with fibrous pseudometaplasia of the lens epithelial cells and phagocytosed silicone oil deposits in the epithelial cells
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