1,721,015 research outputs found
OPPOSING EFFECTS OF ASCORBATE ON COLLAGEN AND ELASTIN DEPOSITION IN THE NEONATAL RAT AORTA
No full textAscorbic acid plays an important role in connective tissue metabolism, where, among other effects, it acts as a reducing factor in the reactions catalyzed by prolyl and lysyl hydroxylases. In vitro, ascorbic acid has been shown to have a positive influence on collagen synthesis at pre- and/or post-translational levels and a negative effect on elastin production. In the present work, the effects of vitamin C on extracellular matrix deposition have been studied in vivo. Stereological analysis on electron micrographs showed, compared to age-matched controls, a 50 to 60% increase of collagen deposition in the media and in the adventitia of the aorta of rats treated for 30 days from the 18th day of life with 10% ascorbate in their drinking water. By contrast, elastin volume density was significantly reduced by the treatment at all ages examined. These morphological data were supported by in situ hybridization observations showing enhanced collagen type I mRNA and reduced elastin mRNA expression upon treatment. Although vitamin C did not inhibit lysyl oxidase activity in vivo, being only slightly higher than in controls, enzyme activity was significantly reduced, when high doses of ascorbate were added in vitro. Lysyl oxidase activity may be a function of enhanced collagen metabolism rather than a direct effect of the vitamin on the enzyme activity. These data indicate that ascorbate exerts opposite effects on the deposition of two major components of the extracellular matrix in vivo, at least during periods of rapid growth
Localized effects of transforming growth factor beta on extracellular matrix gene expression during wound healing. Excisional wound model.
No full textThe effect of transforming growth factor-beta 1 (TGF-beta 1) on matrix gene expression has been investigated during the process of wound repair, where the formation of new connective tissue represents a critical step in restoring tissue integrity. Split-thickness excisional wounds in the pig were studied by in situ hybridization in order to obtain subjective findings on the activity and location of cells involved in matrix gene expression after the administration of recombinant TGF-beta 1. Data focus on the stimulatory role of this growth factor in granulation tissue formation, on the enhanced mRNA content of collagen types I and III, fibronectin, TGF-beta 1 itself, and on the reduction in stromelysin mRNA, suggesting that increased matrix formation measured after treatment with TGF-beta 1 is due to fibroplasia regulated by the abundance of mRNAs for several different structural, matrix proteins as well as inhibition of proteolytic phenomena elicited by metalloproteinases. These studies reveal elastin mRNA early in the repair process, and elastin mRNA expression is enhanced by administration of TGF-beta 1. Moreover, we show that TGF-beta 1 was auto-stimulating in wounds, accounting, at least in part, for the persistent effects of single doses of this multipotential cytokine
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
Connective tissue in skin biopsies from patients suffering systemic sclerosis
No full textLittle information is available on elastin during systemic sclerosis since biochemical and morphological data have primarily focused on collagen and glycosaminoglycan alterations of connective tissues in this pathological process. We performed ultrastructural, morphometric, biochemical and in situ hybridisation analyses on skin biopsies from patients affected by scleroderma and from site and age-matched control subjects. Affected skin revealed alterations in the distribution and organisation of collagen bundles and fibrils together with zonal increase of the microfibrillar component. Elastic fibres were significantly more numerous than in control shin, were more frequently vacuolated and characterised by electron-dense inclusions; moreover, morphometric analysis provided evidence for a significant increase of the percentage of both collagen bundles and elastin fibres in the measured tissue, compared to normal skin. Biochemical analysis seemed to confirm the increased elastin content per unit of dried weight tissue in sclerodermic skin. Differences observed among patients were only partially associated with disease duration and/or to severity of clinical manifestations. The abnormal amount of elastic fibres observed in skin biopsies from patients, and data from in situ hybridisation suggest the presence of a deregulation of the whole extracellular matrix that might be related to the role of cytokines such as TGF-beta, which has already been suggested to be involved in systemic sclerosis and in enhanced collagen and elastin production
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
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