1,720,963 research outputs found
Thyroid hormone and diabetes:an anti-apoptotic pro-survival opportunity for pancreatic b cells.
Full text linkPancreatic β cell loss is the key factor in the pathogenesis of both type 1 and type 2 diabetes, being mainly due to apoptosis of the β cell. Therefore, it is conceivable that a valuable approach to treat or even to prevent the onset of diabetes may imply an anti-apoptotic pro-survival therapy of β cell.
Ex vivo islet cell culture in the presence of stimulating factors prior to transplantation is considered a good strategy in contrast to the short conclusion of islets transplantation. Previously, I demonstrated how T3 can increase β cell function via specific activation of Akt; therefore I, firstly, hypothesized that thyroid hormone T3 can be considered a promising candidate for the in vitro expansion of islet cell mass. Rat pancreatic islets have been isolated by collagenase digestion and cultured in the presence or not of T3 10⁻⁷ M. Islets viability has been evaluated by two different dyes, one cell-permeable green fluorescent and propidium iodide, and by the analysis of core cell damage upcoming. Moreover, islets function has been evaluated by insulin secretion. The ability of β cells to counteract apoptosis induced by streptozotocin has been analyzed by TUNEL assay. In addition, core cell damage was sensibly reduced by T3, suggesting the preservation of the β cells integrity during the culture period. I demonstrated that treatment of primary cultures of rat pancreatic islets with T3 results in augmented β-cell vitality and function. Since even insulin secretion was sensibly augmented by T3 stimulation. Moreover the strong increment shown in Akt activation suggests the involvement of this pathway in the observed phenomena. This study indicate T3 as a good factor to improve ex vivo islets cell culture.
In the second part of my study I demonstrated that the thyroid hormone T3 counteracts the onset of a Streptozotocin (STZ) induced diabetes in wild type mice. To test my hypothesis diabetes has been induced in Balb/c male mice by multiple low dose Streptozotocin injection and a group of mice was contemporaneously injected with T3. After 48 h mice were tested for glucose tolerance test, insulin serum levels and then sacrificed. Whole pancreata were utilized for morphological and biochemical analyses, while protein extracts and RNA were utilized for expression analyses of specific molecules. The results showed that islets from T3 treated mice were comparable to age- and sex-matched control, untreated mice in number, shape, dimension, consistency, ultrastructure, insulin and glucagon levels, TUNEL positivity and caspases activation, while all the cited parameters and molecules were altered by STZ alone. The T3-induced pro survival effect was associated with a strong increase in phosphorylated Akt. Moreover, T3 administration prevented the STZ-dependent alterations in glucose blood level, both during fasting and after glucose challenge, as well as in insulin serum level. In conclusion I demonstrated that T3 could act as a protective factor against STZ induced diabetes
The thyroid hormone T3 improves function and survival of rat pancreatic islets during in vitro culture
No full textThe Thyroid Hormone T3 Improves Function and Survival of Rat Pancreatic Islets during In Vitro Culture.
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Triiodothyronine (T3) prevents fasting-induced skeletal muscle atrophy in vitro and in vivo
No full textGoing 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
Effects of thyroid hormones on ovary granulosa cells: regulation of proliferation, survival and function.
No full textThyroid Hormones (T3 and T4): Dual Effect on Human Cancer Cell Proliferation
No full textSeveral findings suggest that the patient's hormonal context plays a crucial role in determining cancer outcome. The exact nature of thyroid hormone action on tumour growth has not been established yet, in fact contrasting data show thyroid hormones have a promotory or an inhibitory action on cancer cell proliferation depending on the case. We hypothesized that not only tissue specificity, but also specific mutations occurring during tumoral development in different thyroid hormone cellular targets are responsible for this dual effect. To test our hypothesis we analysed, by time-course and bromodeoxyuridine assay, thyroid hormone effects on the proliferation of six cancer cell lines originating from the same tissue or organ but carrying different mutations (in phospho-inositide 3 kinase or β-catenin genes). The data obtained in this study show how mutations that affect the balance between degradation and stabilization of β-catenin assume a remarkable importance in determining the cell-specific thyroid hormone effect on cell growth
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
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