1,721,061 research outputs found
Oxidative stress and anemia in chronic hemodialysis: The promise of bioreactive membranes
No full textPatients with advanced chronic kidney disease are characterized by an imbalance between pro- and antioxidant factors, and increased oxidative stress has been associated with complications of end-stage renal disease such as atherosclerosis, beta(2)-Microglobulin amyloidosis and anemia. Antioxidants such as vitamin E work by inhibiting LDL oxidation by oxidants and by limiting cellular response to oxidized LDL, and are potentially useful adjuncts to the usual medical therapy provided to such patients. In chronic hemodialysis (HD) patients, vitamin E therapy may be administered in the form of dietary supplementation, or as an integral part of the HD procedure in the form of bioreactive dialysis membranes, in which the blood surface has been modified with a-tocopherol. Since blood membrane interaction plays a key role in generating oxidative stress, direct free radical scavenging at the membrane site is a logical approach. Dialysis with vitamin E-coated membranes (VECM) is associated with an improvement in circulating biomarkers of lipid peroxidation. Other than antioxidant activity, the modified surface appears to render these dialyzers more biocompatible, in that cellulose-based membranes behave similar to synthetic dialyzers in terms of cytokine induction. In small studies in chromic HD patients, both dietary vitamin E supplementation as well as use of VECM have been associated with reduced RBC fragility, prolonged RBC lifespan, and improvements in hemoglobin and rHuEpo requirements. Newer VECM based on polysulfone bring us further down the road towards complete biocompatibility, and represent a promising therapy against oxidative stress in chronic HD patients. Copyright (c) 2008 S. Karger AG, Basel
Polymyxin-B Hemoperfusion and Endotoxin Removal: Lessons from a Review of the Literature
No full textSepsis involves a complex interaction between bacterial toxins and the host immune system. Endotoxin, a component of the outer membrane of Gram-negative bacteria, is involved in the pathogenesis of sepsis producing proinflammatory cytokines and activating the complement system, and is thus an ideal potential therapeutic target. Direct hemoperfusion using polymyxin B-immobilized fiber column (PMX-F) has been shown to bind and neutralize endotoxin in both in vitro and in vivo studies. Therefore, this extracorporeal therapy with PMX-F can potentially interrupt the biological cascade of sepsis. A systematic review of the published literature found positive effects of PMX-F on blood pressure and dopamine/dobutamine use, the PaO(2)/FiO(2) ratio, endotoxin removal, and mortality It should be noted, however, that many of the analyzed studies were of suboptimal quality, which may then exaggerate the magnitude of these effects Since this meta-analysis, other studies have been published including a multicenter randomized controlled trial on abdominal septic shock. In this study, PMX-F, when added to conventional therapy, significantly improved hemodynamics and organ dysfunction, and reduced 28-day mortality in this targeted population. There is clear biological rationale for endotoxin removal in the clinical management of severe sepsis and septic shock. The current literature seems to provide some support for this premise, and provides the basis for further rigorous study. Copyright (C) 2010 S Karger AG, Base
Cardiorenal Syndrome: A Complex Series of Combined Heart/Kidney Disorders
No full textOver the last decade, it has become increasingly clear that the cardiovascular and renal systems are interdependent. Primary disorders of either system have been shown to disturb the other system. As a result, a class of cardiorenal syndrome (CRS) has been identified wherein a vicious cycle is established in which acute/chronic dysfunction of either the kidney or the heart exacerbates the loss of function in the other organ. The ADQI organization has proposed a classification derived from a consensus conference held in 2008. CRS is classified as a disorder of the heart and kidneys whereby acute or chronic dysfunction in one organ may induce acute or chronic dysfunction in the other. The general definition has been expanded into five subtypes: CRS type 1 = acute worsening of heart function (acute heart failure-acute coronary syndrome) leading to kidney injury and/or dysfunction; CRS type 2 = chronic abnormalities in heart function (chronic heart failure-chronic heart disease) leading to kidney injury or dysfunction; CRS type 3 = acute worsening of kidney function (acute kidney injury) leading to heart injury and/or dysfunction; CRS type 4 = chronic kidney disease (chronic kidney disease) leading to heart injury, disease and/or dysfunction; and CRS type 5 = systemic conditions leading to simultaneous injury and/or dysfunction of heart and kidney. A major problem with previous terminology was that it did not allow for identification of pathophysiological interactions occurring in the different types of combined heart/kidney disorders. The subdivision into different subtypes seems to provide a better approach to this syndrome. Copyright (C) 2011 S. Karger AG, Base
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
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
- …
