1,720,962 research outputs found
Effects of intermittent parathyroid hormone (PTH) administration on SOST mRNA and protein in rat bone
No full textSclerostin, the secreted protein product of the SOST gene, which is mainly expressed by osteocytes, has recently been proposed as a negative regulator of bone osteoblastogenesis. Chronic elevation of PTH reduces SOST expression by osteocytes, while controversial results have been obtained by intermittent PTH administration. We have investigated the effects of intermittently administered PTH on SOST expression and sclerostin localization, comparing them with those of controls, as they appeared in three different bone segments of rat tibia: secondary trabecular metaphyseal and epiphyseal bone, and cortical diaphyseal bone. The histomorphometric results demonstrate that PTH enhances bone turnover through anabolic effects, as shown by the association of increased bone resorption variables with a significant rise in BV/TV, Tb.Th and Tb.N and a fall in Tb.Sp. PTH induces a SOST mRNA and protein fall in secondary metaphyseal trabeculae, diaphyseal bone and in epiphyseal trabeculae. Numbers of sclerostin immunopositive osteocytes/mm2 show no change, compared with controls; there are fewer sclerostin-positive osteocytes in secondary metaphyseal trabeculae than in the other two bone areas, both in the control and PTH groups. The low numbers of sclerostin-positive osteocytes in the metaphyseal trabecular bone seem to be directly related to the fact that this area displays a high remodeling rate. The anabolic effects of PTH are in line with the fall of SOST mRNA and protein in all the three bone segments examined; the rise of bone turnover supports a negative role of SOST in bone formation. © 2007 Springer Science+Business Media B.V
OPG and RANKL mRNA and protein expressions in the primary and secondary metaphyseal trabecular bone of PTH-treated rats are independent of that of SOST
No full textSclerostin, encoded by the SOST gene, is a recently identified protein which seems to affect bone remodeling by inhibiting bone formation via Wnt pathways. A previous study on OPG and RANKL, two cytokines involved in the control of osteoclastogenesis, showed that the anabolic effect produced by intermittent treatment with parathyroid hormone was characterized by an increase in OPG/RANKL mRNA ratio in the primary spongiosa of metaphyseal bone of rat femur, and by its falling in the secondary spongiosa, in comparison to controls (Silvestrini et al. (2007a)). Considering that Wnt pathway components seem to regulate osteoclast formation and bone resorption by repression of RANKL transcription and by positive regulation of OPG gene in osteoblastic cells, we have evaluated, in the same rats, whether and how SOST mRNA and protein in the primary and secondary metaphyseal bone are affected by PTH. SOST mRNA and protein significantly fell in both primary and secondary spongiosa where only a few osteocytes were positive to sclerostin. These data show that in the two metaphyseal areas no relationship does exist between the trends of OPG and RANKL mRNA and that of SOST, suggesting that there are no direct links between the effects induced by PTH on these molecules, at least in terms of gene expression
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
NADPH oxidase-dependent redox signaling in human heart failure: Relationship between the left and right ventricle
No full textOxidative stress resulting from increased superoxide generation by NADPH oxidase is implicated in the pathophysiology of human heart failure. Downstream targets of NADPH oxidase remain undefined and available information is restricted to the left ventricle (LV). Thus, we aimed to assess the cascade of events triggered by increased NADPH oxidase activity (lipid peroxidation and activation of mitogen-activated protein kinases ERK 1/2, JNK and p38) and their mutual relationship in right (RV) and (LV) of end-stage failing human hearts. When compared to control ventricles, diseased RV and LV showed a significant increase in NADPH oxidase superoxide production that positively correlated with p47(phox) membrane translocation (RV: r=0.76, P < 0.001; LV: r=0.79, P < 0.001). MDA content, a marker of lipid peroxidation, was also enhanced and ERK and p38, but not JNK, were activated. For all these relevant steps of the oxidative stress pathway, a significant correlation was observed between LV and RV from the same heart (NADPH-dependent superoxide production: r=0.678, P < 0.0055; MDA: r=0.95, P < 0.0001; p-p38/p38 ratio: r=0.926, P < 0.0001; p-ERK/ERK ratio: r=0.913, P < 0.0001). We concluded that in human heart failure, both ventricles are targets of NADPH oxidase superoxide generation which in turn may trigger the coordinated activation of downstream signaling components. This pathway may contribute to adverse remodeling of the LV and RV and subsequent progression toward end-stage heart failure, suggestive of new therapeutic targeting strategy. (c) 2007 Elsevier Inc. All rights reserved
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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