1,720,960 research outputs found
MMH CELLS: AN IN VITRO MODEL FOR THE STUDY OF RETINOL-BINDING PROTEIN REGULATED SECRETION
No full textThe untransformed stable cell line Met murine hepatocytes (MMH), generated from liver explants of transgenic mice expressing a constitutively active truncated form of the human hepatocyte growth factor receptor (cyto-Met), represents an innovative tool for in vitro studies of liver function. In the present report, we show that the MMH-D3 line isolated from the liver of a 3-day-old mouse is a useful model to investigate the regulation of the synthesis and secretion of retinol-binding protein (RBP) by retinol (vitamin A alcohol). Experiments with Northern blot hybridization, metabolic labeling of cellular proteins followed by immunoprecipitation, and Western blot analysis demonstrated that, similarly to the in vivo situation, in MMH-D3 cells the presence of retinol does not affect transcriptional and translational rate of the REP gene but is essential for regulating the secretion rate of the protein. Unlike HepG2 human hepatocarcinoma cells used thus far in studies of retinoid metabolism, including the synthesis and secretion of REP, vitamin A deficiency causes, in MMH-D3 cells, the inhibition of REP secretion and the protein accumulation in the cell, whereas retinol repletion promptly results in REP secretion. This model will be very useful in future studies on vitamin A distribution in the organism
Retinol regulates retinol-binding protein (RBP) but not transthyretin (TRT) secretion from the hepatocyte
No full text
The new murine hepatic 3A cell line responds to stress stimuli by activating an efficient Unfolded Protein Response (UPR)
Full text linkIn the present study we have investigated the properties of a novel cell line (3A cells) obtained from the liver of 14.5days post coitum (dpc) wild-type mouse embryo. 3A cells morphology was characterized by fluorescent localization of F-actin and β-catenin. The expression of specific genes and proteins essential to liver function in these cells was comparable or even more efficient then in the differentiated hepatocytic cell line MMH-D6. 3A cells also showed the capability to excrete molecules in extracellular spaces resembling functional bile canaliculi, glycogen storage activity and the ability to control retinol-binding protein 4 secretion in response to retinol deprivation. Their response to the exogenous stress stimulus induced by tunicamycin was analysed by PCR Pathway Array containing 84 genes involved in the Unfolded Protein Response (UPR). 3A cells were shown to activate the UPR following a typical stressful event, indicating that this cellular model could be further exploited to investigate hepatic proteins secretion and specific reaction to different injuries
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
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