1,720,959 research outputs found

    Endothelin-1 plasma concentrations in patients with retinitis pigmentosa

    No full text
    Purpose: The aim of this study was to investigate the behaviour of plasma endothelin-1 (ET-1) levels in patients affected by retinitis pigmentosa (RP) and syndromic RP. Methods: Blood samples were obtained from a group of 40 consecutive patients with RP matched with 35 healthy subjects (HS) as control. We carried out a complete ophthalmological examination. The study group included 26 patients with RP and 14 patients with syndromic RP. Plasma ET-1 levels were determined in duplicate with a specific radioimmunoassay method. Results: In the HS plasma ET-1 levels were 7.48 +/- 2.58 pg/mL The mean of plasma ET-I concentrations in all patients with RP (16.2 +/- 5.6 pg/mL) was significantly (P<0.01) higher than that of HS. Moreover, in the syndromic RP patients, plasma ET-I levels (18.9 +/- 6.8 pg/mL) were higher than those of HS and RP patients (P<0.01). Conclusion: The increase of plasma ET-1 levels in RP patients suggests that ET-I may play a role in the pathophysiology of the diseases involving retinal pigment epithelial cells and the retinal vascular system such as RP. (C) 2010 Elsevier B.V. All rights reserved

    High-resolution spectral domain optical coherence tomography images of Alström syndrome.

    Full text link
    Alström syndrome is a multisystemic disorder characterized by cone-rod dystrophy, hearing loss, obesity, insulin resistance and hyperinsulinemia, type 2 diabetes mellitus, dilated cardiomyopathy, and progressive hepatic and renal dysfunction. The cone-rod retinal dystrophy usually develops within a few weeks after birth. The authors examined a young boy with Alström syndrome by means of microperimetry and spectral domain optical coherence tomography (OCT). Instead of the typical alterations observed in cone-rod dystrophies, the characteristics of the central foveal tissue suggest signs of retinal immaturity, with only a single layer of short, thick cones and rods and immature short outer segments. High-speed and high-resolution spectral domain OCT allowed a detailed analysis of retinal layers in a young patient with Alström syndrome for the first time. Copyright 2010, SLACK Incorporated

    Going Beyond Counting First Authors in Author Co-citation Analysis

    Full text link
    The 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 link
    We 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 link
    We 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
    corecore