1,720,999 research outputs found
Mechanism of autophagy in permeabilized hepatocytes: evidence for regulation by GTP binding proteins.
No full text
Autophagy.
No full textAutophagy or autophagocytosis are terms given to a membrane-mediated process in eukaryotic cells in which portions of cytoplasm are sequestered within vacuoles and degraded by acid hydrolases that are acquired by fusion with lysosomes. Although vacuoles of this type may be formed under pathologic conditions, autophagy is fundamentally a physiologic process which plays indispensible roles in cell restructuring and in the ongoing turnover of cytoplasmic macromolecules. Sequestration is the one step in this pathway that separates autophagy from other degradative processes in the cell. As a volume uptake mechanism it is relatively nonselective (one exception is discussed insection 3.1.2.) and, accordingly, will sequester most organelles and macromolecules in proportion to their cytoplasmic abundance. Moreover, it permits the simultaneous handling of more than one class of macromolecule. This is illustrated in the perfused rat liver by the striking similarity in the accelerated responses of protein and RNA degradation to amino acid deprivation (see Table I).
Although the appearance of the vacuoles varies widely among cells, it is, nevertheless, highly conserved and found in nearly all lower plants and animals as well as in higher species. In yeast, for example, a vacuole that expresses autophagic function (Takeshige et al., 1992; reviewed by Jones and Murdock, 1994) plays a major role in the supply of endogenous amino acids. A similar role for the vacuole is found in germinating seeds (Nishimura and Beevers, 1979) and in the turnover of intracellular proteins in protoplasts of cultured plant cells (Canut et al., 1985). An interesting variant of autophagy is utilized in cell remodeling where irreversible alterations are involved (Marty, 1978; Paavola, 1978 a,b), and an enzymatically unique type degrades intracellular membranes in the amoeba Tetrahymena pyriformis to provide lipid substrate for gluconeogenesis by the glyoxalate pathway (May et al., 1982). Finally, in the mammalian heptocyte, where both protein turnover and the need for endogenous amino acids are large, autophagy is highly expressed and closely regulated by complex amino acid feedback and hormonal mechanisms (reviewed by Mortimore and Pösö, 1987). Taken together, these findings attest to a fundamental role of autophagy in cellular homeostasis.
In this chapter the authors will discuss the main features of general intracellular protein and RNA degradation and the major classes of autophagy and present a current overview of autophagic regulation and its mechanism, focusing primarily on the mammalian hepatocyte which has been extensively studied as a model for the pathway
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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