1,720,985 research outputs found
In Vitro Effects of PTH (1-84) on Human Skeletal Muscle-Derived Satellite Cells
Full text linkParathyroid hormone (PTH) is a hormone secreted by the parathyroid glands. Despite its well-known characterized anabolic and catabolic actions on the skeleton, the in vitro effects of PTH on skeletal muscle cells are limited and generally performed on animal models. The aim of this study was to evaluate the effects of a short impulse of PTH (1-84) on the proliferation and the differentiation of skeletal muscle satellite cells isolated from human biopsies. The cells were exposed for 30 min to different concentrations of PTH (1-84), from 10−6 mol/L to 10−12 mol/L. ELISA was used to assay cAMP and the myosin heavy-chain (MHC) protein. The proliferation was assayed by BrdU and the differentiation by RealTime-qPCR. A statistical analysis was performed by ANOVA followed by Bonferroni’s test. No significant variations in cAMP and the proliferation were detected in the isolated cells treated with PTH. On the other hand, 10−7 mol/L PTH on differentiated myotubes has shown significant increases in cAMP (p ≤ 0.05), in the expression of myogenic differentiation genes (p ≤ 0.001), and in the MHC protein (p ≤ 0.01) vs. untreated controls. This work demonstrates for the first time the in vitro effects of PTH (1-84) on human skeletal muscle cells and it opens new fields of investigation in muscle pathophysiology
Characterization of Skeletal Muscle Endocrine Control in an In Vitro Model of Myogenesis
No full textSkeletal muscle has remarkable regenerative abilities regulated by a highly orchestrated process involving the activation of
cellular and molecular responses, which are dependent on satellite cells. These cells maintain the stem cell population and
provide numerous myogenic cells that proliferate, diferentiate, fuse and lead to new myofber formation for a functional
contractile tissue. We have isolated and characterized satellite cells obtained from human biopsies and established an in vitro
model of myogenesis, evaluating muscle regeneration, monitoring the dynamic increases of the specifc myogenic regulatory
factors and the fnal formation of multinucleated myofbers. As the skeletal muscle is an endocrine tissue able of producing many substances that can act on distant organs, and it can be physiologically modulated by a variety of hormones, we
embarked in a project of characterization of muscle cell endocrinology machinery. The expression of a large array of hormone
receptors was quantifed during the process of myogenesis. The results obtained showed a signifcant and generalized increase
of all the tested hormone receptors along the process of diferentiation of human cultured cells from myoblasts to myocytes.
Interestingly, also the production of the myokine irisin increased in a parallel manner. These fndings point to the human
cultured myoblasts as an ideal model to characterize the skeletal muscle endocrine machinery and its hormonal regulation
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
Measurement of thyroid cell surface antibodies by radioassay using human cultured thyroid cells
No full textThe present report describes a sensitive and quantitative binding radioassay for measurement of thyroid cell surface antibodies (TCSAb). Enzyme-dispersed thyroid cells from surgical specimens of human normal thyroid tissue were used after 7 days of culture. 125l-labelled Graves’ IgG was shown to bind to cultured thyroid cells. The binding was time- and temperature-dependent and increased linearly with the number of thyroid cells. Evidence for specificity was provided by the lack of binding of radioiodinated Graves’ IgG to human fibroblasts and by the negligible binding of 125l-labelled normal IgG to thyroid cells. A dose-dependent inhibition of binding of 125l-labelled Graves’ IgG to thyroid cells was produced by the addition of graded amounts of the unlabelled original Graves’ IgG preparation, but not by normal IgG. Assays for TCSAb were performed on IgG preparations from patients with and without thyroid autoimmune disorders using the original Graves’ IgG preparation as reference stadard. Results were expressed in terms of arbitrary units/100 μg IgG, 1 unit corresponding to the minimum amount of the standard IgG producing a significant inhibition of binding. Negative tests were found in most normal subjects (15/18) while low TCSAb levels (≤1.8 U/100 jug μG) were detected in 3 cases. I ncreased TCSAb levels were found in the majority of the patients with Graves’ disease (14/21), in most of the patients with idiopathic myxedema (9/10) and in all of those with Hashimoto’s thyroiditis (10/10). © 1981, Italian Society of Endocrinology (SIE). All rights reserved
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
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