364 research outputs found

    On the weights of end-pairs in n-end catenoids of genus zero

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    First principles calculations are carried out to analyze adsorption of CO and H2 molecules on a Pt (111) surface and the effect of surface strain on the adsorption energy. A CO molecule is more adsorptive on the Pt (111) surface than a H2 molecule under an ordinary condition. Surface expansion enhances CO poisoning on a Pt (111) surface. On the contrary, a compressive strain reduces adsorptive strength of a CO molecule. Similar tendency is also found in adsorption of a H2 molecule on the bridge, fcc-hollow, and hcp-hollow sites. However, H2 adsorption on the top site is less affected by the strain. As a consequence, the difference of adsorption energies between CO and H2 molecules becomes smaller when compressive strain is introduced into the Pt (111) surface. Based on thermodynamics, surface coverage ratio is quantitatively evaluated with taking into account the effect of surface strain and partial pressure of gas phase. It is revealed that compressive strain improves probability of H2 adsorption on Pt surface

    Two Distinct Pathways Mediated by PA28 and hsp90 in Major Histocompatibility Complex Class I Antigen Processing

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    Major histocompatibility complex (MHC) class I ligands are mainly produced by the proteasome. Herein, we show that the processing of antigens is regulated by two distinct pathways, one requiring PA28 and the other hsp90. Both hsp90 and PA28 enhanced the antigen processing of ovalbumin (OVA). Geldanamycin, an inhibitor of hsp90, almost completely suppressed OVA antigen presentation in PA28α−/−/β−/− lipopolysaccharide blasts, but not in wild-type cells, indicating that hsp90 compensates for the loss of PA28 and is essential in the PA28-independent pathway. In contrast, treatment of cells with interferon (IFN)-γ, which induces PA28 expression, abrogated the requirement of hsp90, suggesting that IFN-γ enhances the PA28-dependent pathway, whereas it diminishes hsp90-dependent pathway. Importantly, IFN-γ did not induce MHC class I expressions in PA28-deficient cells, indicating a prominent role for PA28 in IFN-γ–stimulated peptide supply. Thus, these two pathways operate either redundantly or specifically, depending on antigen species and cell type

    Expression analysis of three isoforms of hyaluronan synthase and hyaluronidase in the synovium of knees in osteoarthritis and rheumatoid arthritis by quantitative real-time reverse transcriptase polymerase chain reaction

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    Hyaluronan is a major molecule in joint fluid and plays a crucial role in joint motion and the maintenance of joint homeostasis. The concentration and average molecular weight of hyaluronan in the joint fluids are reduced in osteoarthritis and rheumatoid arthritis. To elucidate the underlying mechanism, we analyzed the message expression of three isoforms of hyaluronan synthase and hyaluronidase from knee synovium, using real-time reverse transcriptase polymerase chain reaction. Synovia were obtained from 17 patients with osteoarthritis, 14 patients with rheumatoid arthritis, and 20 healthy control donors. The message expression of hyaluronan synthase-1 and -2 in the synovium of both types of arthritis was significantly less than in the control synovium, whereas that of hyaluronidase-2 in the synovium of both arthritides was significantly greater than in the control synovium. The decreased expression of the messages for hyaluronan synthase-1 and -2 and/or the increased expression of the message for hyaluronidase-2 may be reflected in the reduced concentration and decreased average molecular weight of hyaluronan in the joint fluids of patients with osteoarthritis and rheumatoid arthritis

    Relationship between sleep duration and clustering of metabolic syndrome diagnostic components

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    Sayuri Katano1, Yasuyuki Nakamura1,2, Aki Nakamura1, Yoshitaka Murakami3, Taichiro Tanaka4, Toru Takebayashi5, Akira Okayama6, Katsuyuki Miura2, Tomonori Okamura7, Hirotsugu Ueshima2, for HIPOP-OHP Research Group1Cardiovascular Epidemiology, Kyoto Women's University, Kyoto, Japan; 2Department of Health Science, Shiga University of Medical Science, Otsu, Japan; 3Department of Medical Statistics, Shiga University of Medical Science, Otsu, Japan; 4Department of Health Sciences, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Japan; 5Department of Preventive Medicine and Public Health, School of Medicine, Keio University, Tokyo, Japan; 6The First Institute of Health Service, Japan Anti-Tuberculosis Association, Tokyo, Japan; 7Department of Preventive Cardiology, National Cardiovascular Center, Suita, JapanObjective: To examine the relation between sleep duration and metabolic syndrome (MetS).Methods: We examined the baseline data from 4356 healthy workers (3556 men and 800 women) aged 19–69 years. The physical activity of each participant was classified according to the International Physical Activity Questionnaire (IPAQ). We defined four components of MetS diagnostic components in this study as follows: 1) high blood pressure (BP) systolic BP [SBP] ≥ 130 mmHg, or diastolic BP [DBP] ≥ 85 mmHg, or on medication; 2) dyslipidemia (high-density lipoprotein-cholesterol concentration ,40 mg/dL, or triglycerides concentration ≥150 mg/dL, or on medication; 3) impaired glucose tolerance (fasting blood sugar concentration ≥ 110 mg/dL, or if less than 8 hours after meals ≥ 140 mg/dL), or on medication; and 4) overweight (body mass index [BMI] ≥ 25 kg/m2), or obesity (BMI ≥ 30 kg/m2). There were 680 participants in the group, with sleep duration <6 hours (15.6%).Results: Those who had 0–4 MetS diagnostic components, including overweight, accounted for 2159, 1222, 674, 255, and 46 participants, respectively, in the Poisson distribution. Poisson regression analysis revealed that independent factors that contributed to the number of MetS diagnostic components were being male (regression coefficient b = 0.752, P < 0.001), age (b = 0.026, P < 0.001), IPAQ classification (b = -0.238, P = 0.034), and alcohol intake (mL/day) (b = 0.018, P < 0.001). Short sleep duration (<6 hours) was also related to the number of MetS (b = 0.162, P < 0.001). The results of analyses with obesity component showed a similar association.Conclusion: Short sleep duration was positively associated with the number of MetS diagnostic components independent of other lifestyle habits.Keyword: short sleep duration, MetS diagnostic components, obesit

    Screening for yeast mutants defective in recipient ability for transkingdom conjugation with Escherichia coli revealed importance of vacuolar ATPase activity in the horizontal DNA transfer phenomenon

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    Proteobacterium Escherichia coli strains harboring wide-transfer-range conjugative plasmids are able to transfer these plasmids to several yeast species. Whole plasmid DNA is mobilizable in the transkingdom conjugation phenomenon. Owing to the availability of various conjugative plasmids in bacteria, the horizontal DNA transfer has potential to occur between various bacteria and eukaryotes. In order to know host factor genes involved in such conjugation, we systematically tested the conjugability of strains among a yeast library comprising single-gene-knockout mutants in this study. This genome-wide screen identified 26 host chromosomal genes whose absence reduced the efficiency of the transkingdom conjugation. Among the 26 genes, 20 are responsible for vacuolar ATPase activity, while 5 genes (SHP1, CSG2, CCR4, NOT5, and HOF1) seem to play a role in maintaining the cell surface. Lack of either ZUO1 gene or SSZ1 gene, each of which encodes a component of the ribosome-associated cytoplasmic molecular chaperone, also strongly affected transkingdom conjugation.This work was supported in part by Japanese Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (#20570221)
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