1,721,001 research outputs found
Fasting-Induced Increase in Type II Iodothyronine Deiodinase Activity and Messenger Ribonucleic Acid Levels Is Not Reversed by Thyroxine in the Rat Hypothalamus1
No full textSegregation of the intra- and extrahypothalamic neuropeptide Y and catecholaminergic inputs on paraventricular neurons, including those producing thyrotropin-releasing hormone
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Mitochondrial Actions of Thyroid Hormone
No full textThe hypermetabolic effects of thyroid hormones (THs), the major endocrine regulators of metabolic rate, are widely recognized. Although, the cellular mechanisms underlying these effects have been extensively investigated, much has yet to be learned about how TH regulates diverse cellular functions. THs have a profound impact on mitochondria, the organelles responsible for the majority of cellular energy production, and several studies have been devoted to understand the respective importance of the nuclear and mitochondrial pathways for organelle activity. During the last decades, several new aspects of both THs (i.e., metabolism, transport, mechanisms of action, and the existence of metabolically active TH derivatives) and mitochondria (i.e., dynamics, respiratory chain organization in supercomplexes, and the discovery of uncoupling proteins other than uncoupling protein 1) have emerged, thus opening new perspectives to the investigation of the complex relationship between thyroid and the mitochondrial compartment. In this review, in the light of an historical background, we attempt to point out the present findings regarding thyroid physiology and the emerging recognition that mitochondrial dynamics as well as the arrangement of the electron transport chain in mitochondrial cristae contribute to the mitochondrial activity. We unravel the genomic and nongenomic mechanisms so far studied as well as the effects of THs on mitochondrial energetics and, principally, uncoupling of oxidative phosphorylation via various mechanisms involving uncoupling proteins. The emergence of new approaches to the question as to what extent and how the action of TH can affect mitochondria is highlighted. © 2016 American Physiological Society. Compr Physiol 6:1591-1607, 2016.The hypermetabolic effects of thyroid hormones (THs), the major endocrine regulators of metabolic rate, are widely recognized. Although, the cellular mechanisms underlying these effects have been extensively investigated, much has yet to be learned about how TH regulates diverse cellular functions. THs have a profound impact on mitochondria, the organelles responsible for the majority of cellular energy production, and several studies have been devoted to understand the respective importance of the nuclear and mitochondrial pathways for organelle activity. During the last decades, several new aspects of both THs (i.e., metabolism, transport, mechanisms of action, and the existence of metabolically active TH derivatives) and mitochondria (i.e., dynamics, respiratory chain organization in supercomplexes, and the discovery of uncoupling proteins other than uncoupling protein 1) have emerged, thus opening new perspectives to the investigation of the complex relationship between thyroid and the mitochondrial compartment. In this review, in the light of an historical background, we attempt to point out the present findings regarding thyroid physiology and the emerging recognition that mitochondrial dynamics as well as the arrangement of the electron transport chain in mitochondrial cristae contribute to the mitochondrial activity. We unravel the genomic and nongenomic mechanisms so far studied as well as the effects of THs on mitochondrial energetics and, principally, uncoupling of oxidative phosphorylation via various mechanisms involving uncoupling proteins. The emergence of new approaches to the question as to what extent and how the action of TH can affect mitochondria is highlighted. (C) 2016 American Physiological Society
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
Monosynaptic Pathway Between the Arcuate Nucleus Expressing Glial Type II Iodothyronine 5′-Deiodinase mRNA and the Median Eminence-Projective TRH Cells of the Rat Paraventricular Nucleus
No full textVariations 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
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