1,720,973 research outputs found
Elevated Perfusion Pressure Upregulates Endothelin-1 and Endothelin B Receptor Expression in the Rabbit Carotid Artery
No full textTo investigate the hypothesis that high blood pressure activates the endothelin system in the vessel wall, isolated segments of the rabbit carotid artery were subjected to different levels of perfusion pressure. Both preproendothelin-l (ppET-1) mRNA abundance and intravascular ET-1 peptide content were strongly upregulated on raising the intraluminal pressure from 90 to 160 mm Hg for 3 to 12 hours, and this increase in ppET-1 mRNA occurred predominantly in the endothelial cells. Endothelin-converting enzyme-1 and endothelin A receptor (ETA-R) expression were pressure-insensitive, whereas that of the ETB-R in the smooth muscle cells was also significantly enhanced. Both the pressure-induced increase in ppET-1 and ETB-R expression required RNA synthesis because they were abolished by actinomycin D. The nuclear signaling mechanisms involved therein, however, appeared to be different. Thus, the pressure-induced expression of ppET-1 and activation of CCAAT-enhancer binding proteins beta and delta were blocked by the tyrosine kinase inhibitor herbimycin A, whereas ETB-R expression and the nuclear translocation of activator protein-1 were abolished by the protein kinase C inhibitor Ro 31-8220. One consequence of these presumably deformation-induced changes in gene expression was an increased rate of apoptosis of the smooth muscle cells in the media that if transferable to the situation in human blood vessels may contribute to hypertension-induced arterial remodeling
Pressure-Induced Upregulation of Preproendothelin-1 and Endothelin B Receptor Expression in Rabbit Jugular Vein In Situ
No full text
Abstract
—Upregulation of endothelin-1 (ET-1) synthesis in venous bypass grafts in response to arterial levels of blood pressure may play a major role in graft failure. To investigate this hypothesis, isolated segments of the rabbit jugular vein were perfused at physiological (0 to 5 mm Hg) and nonphysiological (20 mm Hg) levels of intraluminal pressure. As judged by reverse transcription–polymerase chain reaction analysis (mRNA level), neither endothelin-converting enzyme nor endothelin A receptor expression appeared to be pressure sensitive. In contrast, there was a profound and time-dependent increase in endothelial prepro-ET-1 mRNA and intravascular ET-1 abundance (by ELISA) as well as in smooth muscle endothelin B receptor mRNA and functional protein (by superfusion bioassay) on raising the perfusion pressure from 5 to 20 mm Hg, but not from 0 to 5 mm Hg, for up to 12 hours. Video microscopy analysis revealed that the segments were distended by 75% at 5 mm Hg and near maximally at 20 mm Hg compared with the resting diameter at 0 to 1 mm Hg. Treatment of the segments with actinomycin D (1 μmol/L), the specific protein kinase C inhibitor, Ro 31–8220 (0.1 μmol/L), or the c-Src family–specific tyrosine kinase inhibitor, herbimycin A (0.1 μmol/L), demonstrated that the pressure-induced expression of these gene products occurs at the level of transcription and requires activation of protein kinase C, but not c-Src. In venous bypass grafts such deformation-induced changes in gene expression may contribute not only to acute graft failure through ET-1–induced vasospasm but also to endothelin A receptor– and/or endothelin B receptor–mediated smooth muscle cell hyperplasia and graft occlusion.
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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
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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