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This study aims to reveal the reason for the increased force of 5-hydroxytryptamine-induced contraction of endotheliumdenuded skeletal muscle arteries of diabetic rats in the presence of perivascular adipose tissue (PVAT). Our data on rat gracilis arteries show that i) PVAT of skeletal muscle arteries of healthy and diabetic rats releases hydrogen peroxide (H2O2), ii) higher concentrations of 5-hydroxytryptamine increase the production of H2O2 in PVAT; iii) an enhanced PVAT production of H2O2 is the main, if not the only, reason for the sensitization of arterial contraction to 5-hydroxytriptamine-induced contraction in diabetes and iv) endothelium antagonizes the effect of PVATderived H2O2.

Item does not contain fulltext, BACKGROUND AND AIMS: The Cochrane Hepato-Biliary Group (CHBG) is one of the 52 collaborative review groups within The Cochrane Collaboration. The activities of the CHBG focus on collecting hepato-biliary randomized clinical trials (RCT) and controlled clinical trials (CCT), and including them in systematic reviews with meta-analyses of the trials. In this overview, we present the growth of The CHBG Controlled Trials Register, as well as the systematic reviews that have been produced since March 1996. RESULTS: The CHBG register includes almost 11,000 RCT and 700 CCT publications. The earliest RCT in the register were published in 1955, and the earliest CCT in 1945. From 1945 to 1980, there were less than 100 publications each year. From 1981 to 1997, their number increased from over 100 to 600 a year. After 1997, the number of publications seems to have been decreasing. The CHBG has published 199 protocols for systematic reviews and 107 systematic reviews through to August 2009 in which 21% of the RCT and CCT were included. The CHBG reviews have been cited approximately 1200 times. CONCLUSIONS: A large amount of work has been carried out since 1996. However, there is still much to do, as the CHBG register contains a great number of RCT and CCT on topics that have not yet been systematically reviewed.

This work deals with the numerical description of dilute polydispersed and turbulent two-phase flows. The method used to describe the two-phase flow is based on the Eulerian-Lagrangian approach. The carrier phase turbulent flow behavior is modeled utilizing Large Eddy Simulation (LES). Most of the recent DNS investigations attempting to provide insight into particle-fluid interaction mechanisms are performed on simple, mostly homogeneous turbulent flows with very low Reynolds numbers. In contrast to this, LES is an opportunity to extend this studies to flows with significantly higher Reynolds numbers and to more complex geometries. Moreover, it is less restrictive to flows containing particles, larger than the Kolmogorov length scale. The main objective of this work is to assess the state of the art capabilities of the two-phase LES and to identify weak points. Recommendations for additional model development for increasing the predictive ability are derived. The reliability of transfer of findings from one configuration to others is assessed. The conclusions are based on a systematic variation of relevant flow parameters, such as the Reynolds number and the Stokes number, so that a wide range of applications is covered. Therefore, several particle-laden flow configurations (two plane channel flows, a free jet and an evaporating spray at low temperature) are investigated. Special attention is paid to the prediction of the particle preferential accumulation, because of its importance for simulations of mixing and combustion in turbulent flows. By performing a systematic variation of the particle Stokes number (here defined as the ratio of the particle time scale to the Kolmogorov time scale of the fluid) and the flow Reynolds number, it is observed that the maximum preferential accumulation occurs at a constant Stokes number and that this number does not depend on the Reynolds number. The magnitude of the accumulation, however, depends on the Reynolds number of the f

Several liver diseases have been associated with oxidative stress. Accordingly, antioxidants have been suggested as potential therapeutics for various liver diseases. The evidence supporting these suggestions is equivocal.

Udgivelsesdato: 2009-Apr, BACKGROUND: Meta-analysis of randomized clinical trials (RCTs) with low risk of bias is considered the highest level of evidence available for evaluating an intervention. Bias in RCTs may overestimate or underestimate the true effectiveness of an intervention. METHODS: The causes of bias in surgical trials as described by The Cochrane Collaboration, and the methods that can be used to avoid them, are reviewed. RESULTS: Blinding is difficult in many surgical trials but careful trial design can reduce the bias risk due to lack of blinding. It is possible to conduct surgical trials with low risk of bias by using appropriate trial design. CONCLUSION: The risk of providing a treatment based on a biased effect estimate must be balanced against the difficulty of conducting trials with very low risk of bias. Better understanding of the risk of bias may result in improved trials with a closer estimate of the true effectiveness of an intervention.

Udgivelsesdato: 2008

BACKGROUND: Oxidative stress may cause gastrointestinal cancers. The evidence on whether antioxidant supplements are effective in preventing gastrointestinal cancers is contradictory. OBJECTIVES: To assess the beneficial and harmful effects of antioxidant supplements in preventing gastrointestinal cancers. SEARCH STRATEGY: We identified trials through the trials registers of the four Cochrane Review Groups on gastrointestinal diseases, The Cochrane Central Register of Controlled Trials in The Cochrane Library (Issue 2, 2007), MEDLINE, EMBASE, LILACS, SCI-EXPANDED, and The Chinese Biomedical Database from inception to October 2007. We scanned reference lists and contacted pharmaceutical companies. SELECTION CRITERIA: Randomised trials comparing antioxidant supplements to placebo/no intervention examining occurrence of gastrointestinal cancers. DATA COLLECTION AND ANALYSIS: Two authors (GB and DN) independently selected trials for inclusion and extracted data. Outcome measures were gastrointestinal cancers, overall mortality, and adverse effects. Outcomes were reported as relative risks (RR) with 95% confidence interval (CI) based on random-effects and fixed-effect model meta-analysis. Meta-regression assessed the effect of covariates across the trials. MAIN RESULTS: We identified 20 randomised trials (211,818 participants), assessing beta-carotene (12 trials), vitamin A (4 trials), vitamin C (8 trials), vitamin E (10 trials), and selenium (9 trials). Trials quality was generally high. Heterogeneity was low to moderate. Antioxidant supplements were without significant effects on gastrointestinal cancers (RR 0.94, 95% CI 0.83 to 1.06). However, there was significant heterogeneity (I(2) = 54.0%, P = 0.003). The heterogeneity may have been explained by bias risk (low-bias risk trials RR 1.04, 95% CI 0.96 to 1.13 compared to high-bias risk trials RR 0.59, 95% CI 0.43 to 0.80; test of interaction P < 0.0005), and type of antioxidant supplement (beta-carotene potentially