85 research outputs found
A Spectroscopic Reconnaissance of UV-Bright Stars
We have carried out spectroscopic observations and made preliminary
classifications of 62 UV-bright stars identified by Lanning on plates taken by
A. Sandage. The goal was to search for "interesting" objects, such as
emission-line stars, hot sub-dwarfs, and high-gravity stars. Our targets were
grouped into two samples, a bright, B < 13, sample of 35 stars observed with
the Kitt Peak 2.1m telescope and a faint, 13< B < 16, sample of 27 stars
observed with the Hobby-Eberly Telescope. We find 39% fairly normal O-mid B
stars, 15% late ~B-late A stars and 32% F-G stars, with 13% of the stars being
high gravity objects, composite, or otherwise peculiar. Included are four
emission-line stars, three composite systems. Thus one out of every ten Lanning
stars is "interesting" and may deserve individual study. Stars in the bright
sample are often found to be late F or early G stars, although this sample does
include interesting stars as well. No such large contamination occurs among the
fainter stars, however, owing to "deselection" of these stars by interstellar
reddening in the low-latitude fields of the survey.Comment: 9 pages in total, to appear in February 2002 issue of P.A.S.
Discovery of a Hard X-Ray Source, SAX J0635+0533, in the Error Box of the Gamma-Ray Source 2EG 0635+0521
We have discovered an x-ray source, SAX J0635+0533, with a hard spectrum
within the error box of the GeV gamma-ray source in Monoceros, 2EG J0635+0521.
The unabsorbed x-ray flux is 1.2*10^-11 erg cm^-2 s^-1 in the 2-10 keV band.
The x-ray spectrum is consistent with a simple powerlaw model with absorption.
The photon index is 1.50 +/- 0.08 and we detect emission out to 40 keV. Optical
observations identify a counterpart with a V-magnitude of 12.8. The counterpart
has broad emission lines and the colors of an early B type star. If the
identification of the x-ray/optical source with the gamma-ray source is
correct, then the source would be a gamma-ray emitting x-ray binary.Comment: Accepted to the Astrophysical Journal, 8 page
Bi-allelic JAM2 Variants Lead to Early-Onset Recessive Primary Familial Brain Calcification.
Primary familial brain calcification (PFBC) is a rare neurodegenerative disorder characterized by a combination of neurological, psychiatric, and cognitive decline associated with calcium deposition on brain imaging. To date, mutations in five genes have been linked to PFBC. However, more than 50% of individuals affected by PFBC have no molecular diagnosis. We report four unrelated families presenting with initial learning difficulties and seizures and later psychiatric symptoms, cerebellar ataxia, extrapyramidal signs, and extensive calcifications on brain imaging. Through a combination of homozygosity mapping and exome sequencing, we mapped this phenotype to chromosome 21q21.3 and identified bi-allelic variants in JAM2. JAM2 encodes for the junctional-adhesion-molecule-2, a key tight-junction protein in blood-brain-barrier permeability. We show that JAM2 variants lead to reduction of JAM2 mRNA expression and absence of JAM2 protein in patient's fibroblasts, consistent with a loss-of-function mechanism. We show that the human phenotype is replicated in the jam2 complete knockout mouse (jam2 KO). Furthermore, neuropathology of jam2 KO mouse showed prominent vacuolation in the cerebral cortex, thalamus, and cerebellum and particularly widespread vacuolation in the midbrain with reactive astrogliosis and neuronal density reduction. The regions of the human brain affected on neuroimaging are similar to the affected brain areas in the myorg PFBC null mouse. Along with JAM3 and OCLN, JAM2 is the third tight-junction gene in which bi-allelic variants are associated with brain calcification, suggesting that defective cell-to-cell adhesion and dysfunction of the movement of solutes through the paracellular spaces in the neurovascular unit is a key mechanism in CNS calcification
Analysis of IL12B Gene Variants in Inflammatory Bowel Disease
IL12B encodes the p40 subunit of IL-12, which is also part of IL-23. Recent genome-wide association studies identified IL12B and IL23R as susceptibility genes for inflammatory bowel disease (IBD). However, the phenotypic effects and potential gene-gene interactions of IL12B variants are largely unknow
A systematic review of the role of vitamin insufficiencies and supplementation in COPD
<p>Abstract</p> <p>Background</p> <p>Pulmonary inflammation, oxidants-antioxidants imbalance, as well as innate and adaptive immunity have been proposed as playing a key role in the development of COPD. The role of vitamins, as assessed either by food frequency questionnaires or measured in serum levels, have been reported to improve pulmonary function, reduce exacerbations and improve symptoms. Vitamin supplements have therefore been proposed to be a potentially useful additive to COPD therapy.</p> <p>Methods</p> <p>A systematic literature review was performed on the association of vitamins and COPD. The role of vitamin supplements in COPD was then evaluated.</p> <p>Conclusions</p> <p>The results of this review showed that various vitamins (vitamin C, D, E, A, beta and alpha carotene) are associated with improvement in features of COPD such as symptoms, exacerbations and pulmonary function. High vitamin intake would probably reduce the annual decline of FEV1. There were no studies that showed benefit from vitamin supplementation in improved symptoms, decreased hospitalization or pulmonary function.</p
- âŠ