1,720,958 research outputs found
New tools for the study of cGMP dependent functions: validation in VEGF induced permeability and angiogenesis
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Mitochondrial aldehyde dehydrogenase-2 activation prevents β amyloids induced endothelial cell dysfunction and restores angiogenesis.
No full textAmyloid β peptides (Aβ1-40 and Aβ1-42) cause cerebral degeneration also by exerting antiangiogenic properties, as impairment of angiogenic factors activity and induction of apoptosis and senescence in the endothelium. Amyloid peptides are known to induce oxidative stress. Impairment of mitochondrial aldehyde dehydrogenase 2 (ALDH2) following oxidative stress, results in accumulation of toxic aldehydes, particularly 4-hydroxynoneal (4-HNE). We sought to determine the role of mithocondrial ALDH2 in Aβ-related impairment of angiogenesis. We hypothesized that by increasing the detoxification activity of ALDH2, we would reduce Aβ-driven endothelial injuries and restore angiogenesis. We used a selective ALDH2 activator, Alda-1, assessing its ability to repair mithocondrial dysfunction in the endothelium. Treatment of human endothelial cells with Aβ1-40 (5-50 μM), induced loss of mitochondrial membrane potential, increased cytochrome c release and ROS accumulation. These events were associated with 4-HNE accumulation and decrease in ALDH2 activity (40%), and resulted in disassembly of endothelial junctions, as evidenced by β-catenin phosphorylation, disorganization of adherens and tight junctions, and by disruption of pseudocapillary formation. Alda-1 (10-40 μM) abolished Aβ-induced 4-HNE accumulation, apoptosis, and vascular leakiness, fully restoring the pro-angiogenic endothelial phenotype and responses to FGF-2. Our data document that mitochondrial ALDH2 in endothelium is a target for the vascular effect of Aβ including loss of barrier function and angiogenesis. ALDH2 activation, by restoring mitochondrial functions in endothelium, prevents Aβ-induced dysfunction and antiangiogenic effects. Thus, agents activating ALDH2 may reduce endothelial injuries including those occurring in cerebral amyloid angiopathy, preserving the angiogenic potential of the endothelium
Cultered lymphatic and blood endothelial cells express focal adhesion molecules and deposit fibrillin.
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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