1,720,959 research outputs found
Characterization of GABA(A) receptors expressed in glial cell membranes of adult mouse neocortex using a Xenopus oocyte microtransplantation expression system
No full textCell membranes isolated from nervous tissue can be easily injected into Xenopus oocytes, thereby effectively "microtransplanting" functional neurotransmitter receptors. This technique therefore allows a direct functional characterization of the original membrane receptor/ion channel proteins and the associated molecules while still embedded in their natural lipid environment. Cell membranes will contain components from different types of cells, i.e. neurons and glial cells, expressing their own receptors, with possibly different properties. To study the receptor properties of a single cell type, we injected oocytes with membranes isolated only from glia (gliosomes) of adult mouse neocortex and we focused our work on GABA(A) receptors incorporated in the oocyte cell membrane. We found that GABA(A)-activated currents allowed a good biophysical and pharmacological characterization of glial GABA(A) receptors. Therefore, the microtransplantation of gliosomes into oocytes can represent a good model to study the electrical and pharmacological properties of adult glial cells under different physiological and pathological conditions. Moreover, since gliosomes can be isolated from frozen tissues, this approach can be extended to post-mortem human tissues. (C) 2011 Elsevier B.V. All rights reserved
Spontaneous and repetitive calcium transients in C2C12 mouse myotubes during in vitro myogenesis
No full textFluorescence videomicroscopy was used to monitor changes in the cytosolic free Ca2+ concentration ([Ca2+](i)) in the mouse muscle cell line C2C12 during in vitro myogenesis. Three different patterns of changes in [Ca2+](i) were observed: (i) [Ca2+](i) oscillations; (ii) faster Ca2+ events confined to subcellular regions (localized [Ca2+](i) spikes) and (iii) [Ca2+](i) spikes detectable in the entire myotube (global [Ca2+](i) spikes), [Ca2+](i) oscillations and localized [Ca2+](i) spikes were detectable following the appearance of caffeine-sensitivity in differentiating C2C12 cells. Global [Ca2+](i) spikes appeared later in the process of myogenesis in cells exhibiting coupling between voltage-operated Ca2+ channels and ryanodine receptors. In contrast to [Ca2+](i) oscillations and localized [Ca2+](i) spikes, the global events immediately stopped when cells were perfused either with a Ca2+-free solution, or a solution with TTX, TEA and verapamil. To explore further the mechanism of the global [Ca2+](i) spikes, membrane currents and fluorescence signals were measured simultaneously, These experiments revealed that global [Ca2+](i) spikes were correlated with an inward current, Moreover, while the depletion of the Ca2+ stores blocked [Ca2+](i) oscillations and localized [Ca2+](i) spikes, it only reduced the amplitude of global [Ca2+](i) spikes. It is suggested that, during the earlier stages of the myogenesis, spontaneous and repetitive [Ca2+](i) changes may be based on cytosolic oscillatory mechanisms. The coupling between voltage-operated Ca2+ channels and ryanodine receptors seems to be the prerequisite for the appearance of global [Ca2+](i) spikes triggered by a membrane oscillatory mechanism, which characterizes the later phases of the myogenic process
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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