124 research outputs found
Fast rotating stars resulting from binary evolution will often appear to be single
Rapidly rotating stars are readily produced in binary systems. An accreting
star in a binary system can be spun up by mass accretion and quickly approach
the break-up limit. Mergers between two stars in a binary are expected to
result in massive, fast rotating stars. These rapid rotators may appear as Be
or Oe stars or at low metallicity they may be progenitors of long gamma-ray
bursts.
Given the high frequency of massive stars in close binaries it seems likely
that a large fraction of rapidly rotating stars result from binary interaction.
It is not straightforward to distinguish a a fast rotator that was born as a
rapidly rotating single star from a fast rotator that resulted from some kind
of binary interaction. Rapidly rotating stars resulting from binary interaction
will often appear to be single because the companion tends to be a low mass,
low luminosity star in a wide orbit. Alternatively, they became single stars
after a merger or disruption of the binary system during the supernova
explosion of the primary.
The absence of evidence for a companion does not guarantee that the system
did not experience binary interaction in the past. If binary interaction is one
of the main causes of high stellar rotation rates, the binary fraction is
expected to be smaller among fast rotators. How this prediction depend on
uncertainties in the physics of the binary interactions requires further
investigation.Comment: 2 pages, 1 figure, to be published in the proceedings of IAU 272
"Active OB stars: structure, evolution, mass loss and critical limit", Paris
19-23 July 201
Whole-genome association analysis of treatment response in obsessive-compulsive disorder.
Up to 30% of patients with obsessive-compulsive disorder (OCD) exhibit an inadequate response to serotonin reuptake inhibitors (SRIs). To date, genetic predictors of OCD treatment response have not been systematically investigated using genome-wide association study (GWAS). To identify specific genetic variations potentially influencing SRI response, we conducted a GWAS study in 804 OCD patients with information on SRI response. SRI response was classified as 'response' (n=514) or 'non-response' (n=290), based on self-report. We used the more powerful Quasi-Likelihood Score Test (the MQLS test) to conduct a genome-wide association test correcting for relatedness, and then used an adjusted logistic model to evaluate the effect size of the variants in probands. The top single-nucleotide polymorphism (SNP) was rs17162912 (P=1.76 × 10(-8)), which is near the DISP1 gene on 1q41-q42, a microdeletion region implicated in neurological development. The other six SNPs showing suggestive evidence of association (P<10(-5)) were rs9303380, rs12437601, rs16988159, rs7676822, rs1911877 and rs723815. Among them, two SNPs in strong linkage disequilibrium, rs7676822 and rs1911877, located near the PCDH10 gene, gave P-values of 2.86 × 10(-6) and 8.41 × 10(-6), respectively. The other 35 variations with signals of potential significance (P<10(-4)) involve multiple genes expressed in the brain, including GRIN2B, PCDH10 and GPC6. Our enrichment analysis indicated suggestive roles of genes in the glutamatergic neurotransmission system (false discovery rate (FDR)=0.0097) and the serotonergic system (FDR=0.0213). Although the results presented may provide new insights into genetic mechanisms underlying treatment response in OCD, studies with larger sample sizes and detailed information on drug dosage and treatment duration are needed
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Genome-wide association study in obsessive-compulsive disorder: results from the OCGAS.
Obsessive-compulsive disorder (OCD) is a psychiatric condition characterized by intrusive thoughts and urges and repetitive, intentional behaviors that cause significant distress and impair functioning. The OCD Collaborative Genetics Association Study (OCGAS) is comprised of comprehensively assessed OCD patients with an early age of OCD onset. After application of a stringent quality control protocol, a total of 1065 families (containing 1406 patients with OCD), combined with population-based samples (resulting in a total sample of 5061 individuals), were studied. An integrative analyses pipeline was utilized, involving association testing at single-nucleotide polymorphism (SNP) and gene levels (via a hybrid approach that allowed for combined analyses of the family- and population-based data). The smallest P-value was observed for a marker on chromosome 9 (near PTPRD, P=4.13 × 10(-)(7)). Pre-synaptic PTPRD promotes the differentiation of glutamatergic synapses and interacts with SLITRK3. Together, both proteins selectively regulate the development of inhibitory GABAergic synapses. Although no SNPs were identified as associated with OCD at genome-wide significance level, follow-up analyses of genome-wide association study (GWAS) signals from a previously published OCD study identified significant enrichment (P=0.0176). Secondary analyses of high-confidence interaction partners of DLGAP1 and GRIK2 (both showing evidence for association in our follow-up and the original GWAS study) revealed a trend of association (P=0.075) for a set of genes such as NEUROD6, SV2A, GRIA4, SLC1A2 and PTPRD. Analyses at the gene level revealed association of IQCK and C16orf88 (both P<1 × 10(-)(6), experiment-wide significant), as well as OFCC1 (P=6.29 × 10(-)(5)). The suggestive findings in this study await replication in larger samples
Exonic DNA Sequencing of ERBB4 in Bipolar Disorder
The Neuregulin-ErbB4 pathway plays a crucial role in brain development and
constitutes one of the most biologically plausible signaling pathways implicated
in schizophrenia and, to a lesser extent, in bipolar disorder (BP). However,
recent genome-wide association analyses have not provided evidence for common
variation in NRG1 or ERBB4 influencing
schizophrenia or bipolar disorder susceptibility. In this study, we investigate
the role of rare coding variants in ERBB4 in BP cases with
mood-incongruent psychotic features, a form of BP with arguably the greatest
phenotypic overlap with schizophrenia. We performed Sanger sequencing of all 28
exons in ERBB4, as well as part of the promoter and part of the
3′UTR sequence, hypothesizing that rare deleterious variants would be
found in 188 cases with mood-incongruent psychosis from the GAIN BP study. We
found 42 variants, of which 16 were novel, although none were non-synonymous or
clearly deleterious. One of the novel variants, present in 11.2% of
cases, is located next to an alternative stop codon, which is associated with a
shortened transcript of ERBB4 that is not translated. We
genotyped this variant in the GAIN BP case-control samples and found a
marginally significant association with mood-incongruent psychotic BP compared
with controls (additive model: OR = 1.64,
P-value = 0.055; dominant model:
OR = 1.73.
P-value = 0.039). In
conclusion, we found no rare variants of clear deleterious effect, but did
uncover a modestly associated novel variant that could affect alternative
splicing of ERBB4. However, the modest sample size in this
study cannot definitively rule out a role for rare variants in bipolar disorder
and studies with larger sample sizes are needed to confirm the observed
association
Nursing Diagnosis Risk for falls: prevalence and clinical profile of hospitalized patients
Objectives: to identify the prevalence of the Nursing Diagnosis (ND) Risk for falls in the hospitalizations of adult patients in clinical and surgical units, to characterize the clinical profile and to identify the risk factors of the patients with this ND. Method: a cross-sectional study with 174 patients. The data was collected from the computerized nursing care prescriptions system and on-line hospital records, and analyzed statistically. Results: the prevalence of the ND Risk for falls was 4%. The patients’ profile indicated older adults, males (57%), those hospitalized in the clinical units (63.2%), with a median length of hospitalization of 20 (10-24) days, with neurological illnesses (26%), cardio-vascular illnesses (74.1%) and various co-morbidities (3±1.8). The prevalent risk factors were neurological alterations (43.1%), impaired mobility (35.6%) and extremes of age (10.3%). Conclusion: the findings contributed to evidencing the profile of the patients with a risk of falling hospitalized in clinical and surgical wards, which favors the planning of interventions for preventing this adverse event
Social Cognitive Role of Schizophrenia Candidate Gene GABRB2
10.1371/journal.pone.0062322PLoS ONE84
Overexpression of Reelin Prevents the Manifestation of Behavioral Phenotypes Related to Schizophrenia and Bipolar Disorder
Despite the impact of schizophrenia and mood disorders, which in extreme cases can lead to death, recent decades have brought little progress in the development of new treatments. Recent studies have shown that Reelin, an extracellular protein that is critical for neuronal development, is reduced in schizophrenia and bipolar disorder patients. However, data on a causal or protective role of Reelin in psychiatric diseases is scarce. In order to study the direct influence of Reelin's levels on behavior, we subjected two mouse lines, in which Reelin levels are either reduced (Reelin heterozygous mice) or increased (Reelin overexpressing mice), to a battery of behavioral tests: open-field, black–white box, novelty-suppressed-feeding, forced-swim-test, chronic corticosterone treatment followed by forced-swim-test, cocaine sensitization and pre-pulse inhibition (PPI) deficits induced by N-methyl--aspartate (NMDA) antagonists. These tests were designed to model some aspects of psychiatric disorders such as schizophrenia, mood, and anxiety disorders. We found no differences between Reeler heterozygous mice and their wild-type littermates. However, Reelin overexpression in the mouse forebrain reduced the time spent floating in the forced-swim-test in mice subjected to chronic corticosterone treatment, reduced behavioral sensitization to cocaine, and reduced PPI deficits induced by a NMDA antagonist. In addition, we demonstrate that while stress increased NMDA NR2B-mediated synaptic transmission, known to be implicated in depression, Reelin overexpression significantly reduced it. Together, these results point to the Reelin signaling pathway as a relevant drug target for the treatment of a range of psychiatric disorders
Genetics of self-reported risk-taking behaviour, trans-ethnic consistency and relevance to brain gene expression
Risk-taking behaviour is an important component of several psychiatric disorders, including attention-deficit hyperactivity disorder, schizophrenia and bipolar disorder. Previously, two genetic loci have been associated with self-reported risk taking and significant genetic overlap with psychiatric disorders was identified within a subsample of UK Biobank. Using the white British participants of the full UK Biobank cohort (n = 83,677 risk takers versus 244,662 controls) for our primary analysis, we conducted a genome-wide association study of self-reported risk-taking behaviour. In secondary analyses, we assessed sex-specific effects, trans-ethnic heterogeneity and genetic overlap with psychiatric traits. We also investigated the impact of risk-taking-associated SNPs on both gene expression and structural brain imaging. We identified 10 independent loci for risk-taking behaviour, of which eight were novel and two replicated previous findings. In addition, we found two further sex-specific risk-taking loci. There were strong positive genetic correlations between risk-taking and attention-deficit hyperactivity disorder, bipolar disorder and schizophrenia. Index genetic variants demonstrated effects generally consistent with the discovery analysis in individuals of non-British White, South Asian, African-Caribbean or mixed ethnicity. Polygenic risk scores comprising alleles associated with increased risk taking were associated with lower white matter integrity. Genotype-specific expression pattern analyses highlighted DPYSL5, CGREF1 and C15orf59 as plausible candidate genes. Overall, our findings substantially advance our understanding of the biology of risk-taking behaviour, including the possibility of sex-specific contributions, and reveal consistency across ethnicities. We further highlight several putative novel candidate genes, which may mediate these genetic effects
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