1,721,048 research outputs found
Impact of 719 Trp>Arg polymorphism of KIF 6 gene on coronary artery disease, contrast induced nephropathy and modulation of statin therapy effectiveness
Full text linkImmumomodulating marine glycosphingolipids: combining natural product isolation and chemical synthesis in search of chemical diversity
No full textIt is now well established that sponges of the genus Agelas and Axinella produce α-galactoglycosphingolipids (α-Gal-GSLs, e.g. 1–3), unique glycosphingolipids which are different from common β-glucosyl- or β-galactosyl ceramides from higher animals and plants in that they show an α-galactose as the first sugar of the carbohydrate chain. Natural α-Gal-GSLs possess interesting immunomodulating activities. They are potent ligands of the CD1d antigen presenting protein, and are capable to specifically activate natural killer T cells (N KT cells) in vivo. KRN7000 (4), a synthetic analogue the simplest α-Gal GSLs agelasphin (1) is under clinical trial as a novel anticancer agent, acting through stimulation of the immune system. As a part of our ongoing search of glycolipids from sponges, we discovered a number of more complex alpha-Gal-GSLs, which were tested on murine T-cell populations. The obtained data suggested that the immunostimulating activity is greatly reduced by glycosylation of the galactose 2-OH group, although some subsequent results obtained by other researchers seemed to be in contrast with these findings. This inconsistency was solved by a recent study, demonstrating that alpha-Gal-GSLs glycosylated at 2' or 3' positions are not active themselves, but are processed by the antigen presenting cells (APCs) with removal of the sugars linked to the galactose. In this scenario, we felt that the availability of analogs of alpha-Gal-GSLs, modified at the key position 2' in a way that cannot be affected by APC processing (e.g. 5), would be important to obtain clear-cut results. Therefore, we carried out the stereoselective total synthesis of the alpha-Gal-GSL analogs 5, and evaluated the influence of the structural modification on their immunostimulating activity. The synthetic procedures, the results of the assays, and their implications on the structural requirements for the immunostimulating activity will be discussed.Meanwhile, the analysis of natural alpha-Gal-GSLs from Agelas and Axinella sponges is far from being concluded, and these species are continuing to provide new glycosphingolipids with unprecedented glycosylation patterns. The latest results of this studies, which also contributed to clarify the structure-activity relationship of alpha-Gal-GSLs will be discussed
Switching from Clopidogrel to Prasugrel in patients undergoing PCI: A meta-analytic overview
No full textGlycolipids from Sponges. Part 16. Discoside, a Rare Myo-Inositol-Containing Glycolipid from the Caribbean Sponge Discodermia dissoluta
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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
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