1,721,041 research outputs found
The Effect of Simvastatin on Erythrocyte Membrane Fluidity During Oxidative Stress Induced by Cardiopulmonary Bypass: A Randomized Controlled Study
No full textAbstract: BACKGROUND: Abnormal erythrocyte deformability can cause severe complications during cardiopulmonary bypass (CPB) surgery, including both hemolysis and perfusion abnormalities. OBJECTIVES: The goals of this study were to evaluate changes in erythrocyte membrane fluidity and lipid peroxidation during CPB and to examine the effect of simvastatin treatment on these parameters. METHODS: Patients undergoing cardiac surgery involving CPB were selected and randomized to receive either simvastatin 40 mg/d or placebo for 3 weeks before surgery. Three blood samples were obtained at different times during surgery for analysis of erythrocyte membrane fluidity, anion permeability, and lipid peroxidation. Erythrocyte ghosts were prepared and incubated with a lipophilic fluorescent probe (diphenyl-hexatriene), and fluorescence anisotropy was evaluated by spectrophotofluorimetric assay as a measure of membrane fluidity. Anion permeability was evaluated by the specific absorption of methemoglobin (CM) at 590 and 635 nm after treatment of heparinized blood with NaNO2. The formation of thiobarbituric acid-reactive substances was evaluated as an index of lipid peroxidation. Aspartate transaminase and lactate dehydrogenase were also measured as indices of hemolysis. RESULTS: Forty patients met the inclusion criteria (20 simvastatin, 20 placebo). Their characteristics differed significantly at baseline only in terms of the lipid profile; the statin group had higher levels of high-density lipoprotein cholesterol (P = 0.01) and lower levels of low-density lipoprotein cholesterol (P = 0.001) than the placebo group. CPB was found to significantly modify characteristics of the erythrocyte membrane. Compared with preoperative values, CPB induced decreases in both mean (SD) erythrocyte membrane fluidity and anion permeability (preoperative CM: 0.69 [0.02]; 24-hour postoperative CM: 0.18 [0.02]; P < 0.001) and an increase in mean (SD) membrane lipid peroxidation (preoperative malonyl dialdehyde [MDA]: 0.21 [0.01] nmol/mL; postoperative MDA: 0.10 [0.02] nmol/mL; P < 0.001). Treatment with simvastatin was associated with a significant reduction in mean (SD) membrane lipid peroxidation both preoperatively and at 24 hours postoperatively compared with placebo (preoperative MDA: 0.07 [0.01] vs 0.10 [0.02] nmol/mL, respectively; P < 0.05; postoperative MDA: 0.10 [0.04] vs 0.21 [0.01] nmol/mL; P < 0.05). In addition, statin treatment was associated with significant increases in anion permeability preoperatively and postoperatively compared with placebo (preoperative CM: 0.79 [0.01] vs 0.69 [0.02]; P < 0.01; 24-hour postoperative CM: 0.30 [0.01] vs 0.18 [0.02]; P < 0.01). CONCLUSION: The results of this study suggest that among these patients undergoing CPB surgery, use of simvastatin for 3 weeks before the surgery had significant beneficial effects on erythrocyte membrane fluidity, lipid peroxidation, and anion permeability
Pressure distension stimulates the expression of endothelial adhesion molecules in the human saphenous vein graft
No full textBackground. Mechanical trauma occurring during saphenous vein graft harvesting plays a major role in graft failure after coronary bypass surgery. There is increasing evidence that neutrophil-endothelial interaction is involved in the pathogenesis of early graft occlusion. This study evaluates the effect of pressure distension on the expression of endothelial adhesion molecules in human saphenous vein. Methods. Segments of saphenous vein graft (SVG) were collected from 20 patients undergoing coronary bypass surgery. We evaluated the expression of intercellular adhesion molecule (ICAM-1), vascular cell adhesion molecule (VCAM-1), and P-selectin on SVG endothelium under basal conditions and after pressure distension at 300 mm Hg. In the same experimental setting we also evaluated adhesion of both unstimulated and activated neutrophils to the endothelium of SVG. Results. Control endothelial cells exhibited only a weak staining for intercellular adhesion molecule (ICAM-1), vascular cell adhesion molecule (VCAM-1), and P-selectin, whereas the levels of adhesion molecules increased significantly in the distended veins. Similarly, significantly greater adhesion of both unstimulated and activated neutrophils was observed in distended veins compared with control veins. Conclusions. Pressure distension of SVG before coronary bypass surgery induces upregulation of endothelial adhesion molecules, with subsequent increase in neutrophil adhesion to the endothelium. Neutrophil adhesion to endothelial cells may contribute to early failure of SVG. © 2003 by The Society of Thoracic Surgeons
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Advanced glycation end products in diabetic patients with optimized glycaemic control and their effects on endothelial reactivity: possible implications in venous graft failure
No full textBackground Diabetic patients exhibit an increased risk of saphenous graft occlusion after coronary bypass. Advanced glycation end products (AGEs) are ubiquitous signalling proteins that are associated with vascular and neurological complication of diabetes. The aim of this study is to verify whether AGE levels may promote endothelial cell alterations responsible for vein graft failure. Methods Segments of saphenous vein were obtained from both normal people and diabetic patients (HbA(1c) < 6.0%) at the time of coronary surgery. Cultured endothelial cells were incubated in the absence/presence of AGEs (2 and 20 mu M), and mRNA and protein for both receptor of AGEs (RAGE) and peroxisome proliferator-activated receptors-gamma (PPAR-gamma) were analysed by real-time polymerised chain reaction (PCR) and Western blot analysis. in the same fashion, the cell release of reactive oxygen species (ROS) was estimated in the absence/presence of AGEs by spectro fluori metric analysis. Finally, neutrophil-endothelial adhesion was evaluated in saphenous vein segments with and without the addition of AGEs. Results AGES activated in a dose-dependent manner the expression of RAGE and inhibited PPAR-gamma expression in endothelial cells as testified by both reverse transcription-PCR (RT-PCR) and Western blot analysis. Stimulation of cultured endothelial cells with AGEs significantly enhanced intracellular ROS formation in a dose-dependent manner. Finally, neutrophil-endothelial adhesion was significantly increased after incubation of control veins with AGEs. Conclusions These findings indicate that even in diabetic patients with HbA(1c) < 6.0%, elevated serum levels of AGE determine a sort of a prothrombotic state, providing a common mechanism that could explain the increased rate of vein graft occlusion in this population. Copyright (c) 2009 John Wiley & Sons, Ltd
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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