1,721,007 research outputs found
Structural modifications of HDL and functional consequences
No full textAtherosclerosis. 2006 Jan;184(1):1-7. Epub 2005 Sep 12.
Structural modifications of HDL and functional consequences.
Ferretti G, Bacchetti T, Nègre-Salvayre A, Salvayre R, Dousset N, Curatola G.
SourceInstitute of Biochemistry, Faculty of Medicine, University of Ancona, via Ranieri 1-60131, Italy. [email protected]
Abstract
High density lipoproteins (HDL) are susceptible to structural modifications mediated by various mechanisms including oxidation, glycation, homocysteinylation or enzymatic degradation. Structural alterations of HDL may affect their functional and atheroprotective properties. Oxidants, such as hypochlorous acid, peroxyl radicals, metal ions, peroxynitrite, lipoxygenases and smoke extracts, can alter both surface and core components of HDL. The formation of lipid peroxidation derivatives, such as thiobarbituric acid reactive substances, conjugated dienes, lipid hydroperoxides and aldehydes, is associated with changes of physical properties (fluidity, molecular order) and of apoprotein conformation. Non-enzymatic glycation, generally associated with lipoxidation, leads to form irreversible complexes called advanced glycation end products. These HDL modifications are accompanied with altered biological activities of HDL and associated enzymes, including paraoxonase, CETP and LCAT. Homocysteine-induced modification of HDL is mediated by homocysteine-thiolactone, and can be prevented by a calcium-dependent thiolactonase/paraoxonase. Tyrosylation of HDL induces the formation of dimers and trimers of apo AI, and alters cholesterol efflux. Phospholipases and proteolytic enzymes can also modify HDL lipid and apoprotein structure. HDL modification induces generally the loss of their anti-inflammatory and cytoprotective properties. This could play a role in the pathogenesis of atherosclerosis and neurodegenerative diseases such as Alzheimer's disease.
PMID:16157342[PubMed - indexed for MEDLINE
Antioxidant and cytoprotective properties of high-density lipoproteins in vascular cells
No full textFree Radic Biol Med. 2006 Oct 1;41(7):1031-40. Epub 2006 Jul 12.
Antioxidant and cytoprotective properties of high-density lipoproteins in vascular cells.
Negre-Salvayre A, Dousset N, Ferretti G, Bacchetti T, Curatola G, Salvayre R.
SourceINSERM U 466, Hôpital Rangueil Toulouse, France. [email protected]
Abstract
Beside their key role in the regulation of cholesterol homeostasis, HDL exhibit antioxidant and anti-inflammatory properties that participate to their general antiatherogenic effect. The purpose of this review is to summarize the recent findings on antioxidant activity and cytoprotective cell signalling elicited by HDL against oxidized LDL and proatherogenic agents in vascular cells. HDL exhibit an antioxidant activity efficient to prevent LDL oxidation, or to inactivate newly formed lipid oxidation products. The antioxidant ability of HDL is due to the apoprotein moiety and to the presence of associated enzymes, paraoxonase and PAF-Acetyl Hydrolase. HDL prevent the intracellular oxidative stress and the inflammatory response elicited by oxidized LDL (ox-LDL), by inhibiting the NFkappaB signalling pathway, and the subsequent inflammatory events (expression of adhesion molecules, recruitment and proliferation of mononuclear cells within the vascular wall). HDL prevent ox-LDL-mediated cell activation and proliferation, this being also attributed to the presence in HDL of sphingosine-1 phosphate which modulates the migration and survival of vascular cells. Lastly, HDL inhibit apoptosis elicited by ox-LDL in vascular cells. Recent evidences indicate that, beside their strong antiatherogenic properties, HDL could exert their protective effect in diseases generally associated to inflammatory events.
PMID:16962927[PubMed - indexed for MEDLINE
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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