138 research outputs found

    The Evolution of Compact Binary Star Systems

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    We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

    Sequence variations of ABCB1, SLC6A2, SLC6A3, SLC6A4, CREB1, CRHR1 and NTRK2: association with major depression and antidepressant response in Mexican-Americans

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    We studied seven genes that reflect events relevant to antidepressant action at four sequential levels: (1) entry into the brain, (2) binding to monoaminergic transporters, and (3) distal effects at the transcription level, resulting in (4) changes in neurotrophin and neuropeptide receptors. Those genes are ATP-binding cassette subfamily B member 1 (ABCB1), the noradrenaline, dopamine, and serotonin transporters (SLC6A2, SLC6A3 and SLC6A4), cyclic AMP-responsive element binding protein 1 (CREB1), corticotropin-releasing hormone receptor 1 (CRHR1) and neurotrophic tyrosine kinase type 2 receptor (NTRK2). Sequence variability for those genes was obtained in exonic and flanking regions. A total of 56 280 000 bp across were sequenced in 536 unrelated Mexican Americans from Los Angeles (264 controls and 272 major depressive disorder (MDD)). We detected in those individuals 419 single nucleotide polymorphisms (SNPs); the nucleotide diversity was 0.00054±0.0001. Of those, a total of 204 novel SNPs were identified, corresponding to 49% of all previously reported SNPs in those genes: 72 were in untranslated regions, 19 were in coding sequences of which 7 were non-synonymous, 86 were intronic and 27 were in upstream/downstream regions. Several SNPs or haplotypes in ABCB1, SLC6A2, SLC6A3, SLC6A4, CREB1 and NTRK2 were associated with MDD, and in ABCB1, SLC6A2 and NTRK2 with antidepressant response. After controlling for age, gender and baseline 21-item Hamilton Depression Rating Scale (HAM-D21) score, as well as correcting for multiple testing, the relative reduction of HAM-D21 score remained significantly associated with two NTRK2-coding SNPs (rs2289657 and rs56142442) and the haplotype CAG at rs2289658 (splice site), rs2289657 and rs2289656. Further studies in larger independent samples will be needed to confirm these associations. Our data indicate that extensive assessment of sequence variability may contribute to increase understanding of disease susceptibility and drug response. Moreover, these results highlight the importance of direct re-sequencing of key candidate genes in ethnic minority groups in order to discover novel genetic variants that cannot be simply inferred from existing databases

    Microleakage and Resin-to-Dentin Interface Morphology of Pre-Etching versus Self-Etching Adhesive Systems

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    The purpose of this study was to compare the microleakage and tissue-adhesive interface morphology from Class V restorations using different systems of dentin adhesives. Class V cavities were prepared on buccal surfaces of 27 extracted caries-free molars and premolars. Teeth were randomly assigned to one of three groups: (1) Prime & Bond NT, a 5th generation system using an initial step of total etch followed by a second step of application of a self bonding primer (2) Clearfil SE Bond, a 5th generation adhesive system employing two separate steps of self-etch priming and subsequent bonding (3) One-up Bond F, a 6th generation one step self-etching, self-priming and self-bonding adhesive. Microleakage and interface morphology of teeth restored with these adhesives and a composite resin were evaluated. Kruskal-Wallis Test (p = 0.05) was used to analyze the results. SEM analysis was used to relate interface morphology to microleakage. The mean and (SD) values of microleakage were: Prime and Bond NT: 0.15 (0.33), Clearfil SE Bond: 0.06 (0.17) and One-up Bond F: 2.96 (0.63). The mean microleakage for One-up Bond was significantly higher than for the other groups (p<0.05). Protruding tags in dentin channels were observed in Prime and Bond and Clearfil systems, but not in One-up Bond. The single step adhesive system, although more convenient for the clinician, uses a low viscosity formulation difficult to keep in place on cavity walls. It also tends to be too aggressive and hydrophilic to create an impermeable hybridized tissue-adhesive interfacial layer resistant to microleakage. Two-step adhesive systems, on the other hand, were retained on all segments of the cavosurface during application, and formed a hybridized interfacial layer resistant to microleakage

    Polymorphisms of Serotonin Receptor 2A and 2C Genes and COMT in Relation to Obesity and Type 2 Diabetes

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    BACKGROUND:Candidate genes of psychological importance include 5HT2A, 5HT2C, and COMT, implicated in the serotonin, noradrenaline and dopamine pathways, which also may be involved in regulation of energy balance. We investigated the associations of single nucleotide polymorphisms (SNPs) of these genes with obesity and metabolic traits. METHODOLOGY/PRINCIPAL FINDINGS:In a population of 166 200 young men examined at the draft boards, obese men (n = 726, BMI> or =31.0 kg/m(2)) and a randomly selected group (n = 831) were re-examined at two surveys at mean ages 46 and 49 years (S-46, S-49). Anthropometric, physiological and biochemical measures were available. Logistic regression analyses were used to assess age-adjusted odds ratios. No significant associations were observed of 5HT2A rs6311, 5HT2C rs3813929 and COMT rs4680 with obesity, except that COMT rs4680 GG-genotype was associated with fat-BMI (OR = 1.08, CI = 1.01-1.16). The SNPs were associated with a number of physiological variables; most importantly 5HT2C rs3813929 T-allele was associated with glucose (OR = 4.56, CI = 1.13-18.4) and acute insulin response (OR = 0.65, CI = 0.44-0.94) in S-49. COMT rs4680 GG-genotype was associated with glucose (OR = 1.04, CI = 1.00-1.09). Except for an association between 5HT2A rs6311 and total-cholesterol at both surveys, significant in S-46 (OR = 2.66, CI = 1.11-6.40), no significant associations were observed for the other phenotypes. Significant associations were obtained when combined genotype of 5HT2C rs3813929 and COMT rs4680 were examined in relation to BMI (OR = 1.12, CI = 1.03-1.21), fat-BMI (OR = 1.22, CI = 1.08-1.38), waist (OR = 1.13, CI = 1.04-1.22), and cholesterol (OR = 5.60, CI = 0.99-31.4). Analyses of impaired glucose tolerance (IGT) and type 2 diabetes (T2D) revealed, a 12.3% increased frequency of 5HT2C rs3813929 T-allele and an 11.6% increased frequency of COMT rs4680 GG-genotype in individuals with IGT or T2D (chi(2), p = 0.05 and p = 0.06, respectively). Examination of the combined genotypes of 5HT2C and COMT showed a 34.0% increased frequency of IGT or T2D (chi(2), p = 0.01). CONCLUSIONS:The findings lend further support to the involvement of serotonin, noradrenaline and dopamine pathways on obesity and glucose homeostasis, in particular when combined genotype associations are explored

    CpG-island methylation of the ER promoter in colorectal cancer: analysis of micrometastases in lymph nodes from UICC stage I and II patients

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    Patients with UICC stage II colorectal cancer (CRC) have a risk of approximately 20% to develop disease recurrence after tumour resection. The presence and significance of micrometastases for locoregional recurrence in these patients lacking histopathological lymph node involvement on routine stained HE sections is undefined. Oestrogen receptor (ER) promoter methylation has earlier been identified in CRC. Therefore, we evaluated the methylation status of the ER promoter in lymph nodes from 49 patients with CRC UICC stage I and II as a molecular marker of micrometastases and predictor of local recurrence. DNA from 574 paraffin-embedded lymph nodes was isolated and treated with bisulphite. For the detection of methylated ER promoter sequences, quantitative real-time methylation-specific PCR was used. Of the 49 patients tested, 15 (31%) had ER methylation-positive lymph nodes. Thirteen of those (86%) remained disease free and two (14%) developed local recurrence. In the resected lymph nodes of 34 of the 49 patients (69%), no ER promoter methylation could be detected and none of these patients experienced a local relapse. The methylation status of the ER promoter in lymph nodes of UICC stage I and II CRC patients may be a useful marker for the identification of patients at a high risk for local recurrence

    Human Cytomegalovirus Entry into Dendritic Cells Occurs via a Macropinocytosis-Like Pathway in a pH-Independent and Cholesterol-Dependent Manner

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    Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus that is able to infect fibroblastic, epithelial, endothelial and hematopoietic cells. Over the past ten years, several groups have provided direct evidence that dendritic cells (DCs) fully support the HCMV lytic cycle. We previously demonstrated that the C-type lectin dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) has a prominent role in the docking of HCMV on monocyte-derived DCs (MDDCs). The DC-SIGN/HCMV interaction was demonstrated to be a crucial and early event that substantially enhanced infection in trans, i.e., from one CMV-bearing cell to another non-infected cell (or trans-infection), and rendered susceptible cells fully permissive to HCMV infection. Nevertheless, nothing is yet known about how HCMV enters MDDCs. In this study, we demonstrated that VHL/E HCMV virions (an endothelio/dendrotropic strain) are first internalized into MDDCs by a macropinocytosis-like process in an actin- and cholesterol-dependent, but pH-independent, manner. We observed the accumulation of virions in large uncoated vesicles with endosomal features, and the virions remained as intact particles that retained infectious potential for several hours. This trans-infection property was specific to MDDCs because monocyte-derived macrophages or monocytes from the same donor were unable to allow the accumulation of and the subsequent transmission of the virus. Together, these data allowed us to delineate the early mechanisms of the internalization and entry of an endothelio/dendrotropic HCMV strain into human MDDCs and to propose that DCs can serve as a "Trojan horse" to convey CMV from entry sites to other locations that may favor the occurrence of either latency or acute infection
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