1,721,073 research outputs found
Characterization of a Ca2+-stimulated Mg2+-dependent adenosine triphosphatase in Friend murine erythroleukemia cell plasma membranes.
No full textSince agents which affect Ca2+ fluxes have been shown to affect the commitment to terminal differentiation of murine erythroleukemia cells treated with an inducer of differentiation (Bridges, K., Levenson, R., Housman, D., and Cantley, L. (1981) J. Cell Biol. 90, 542-544), we investigated the presence of Ca2+-transport systems in plasma membranes isolated from these cells. Plasma membranes from murine erythroleukemia cells exhibited a high affinity (Ca2+-Mg2+)-ATPase activity with a Vmax of 29 +/- 4 nmol/mg/min and an apparent K0.5 for free Ca2+ of 0.13 microM. This activity was strongly inhibited in a dose-dependent fashion by low concentrations of trifluoperazine, compound 48/80, lanthanum, and vanadate with I50 of 29 microM, 1.75 micrograms/ml, 1.5 microM, and 0.4 microM, respectively. The inhibitory effect of compound 48/80 was specifically reversed by exogenously added calmodulin. Phosphorylation of plasma membranes with [gamma-32P] ATP followed by sodium dodecyl sulfate electrophoretic analysis at low pH revealed a Ca2+-dependent phosphoprotein with an apparent molecular mass of 138,000 daltons which co-migrated with the Ca2+-dependent phosphoprotein from human erythrocytes and was separable from sarcoplasmic reticulum (Ca2+-Mg2+)-ATPase. The 32P incorporated into the phosphoprotein could be chased with unlabeled ATP and the protein-phosphate bond was unstable at alkaline pH suggesting an acylphosphate ATPase intermediate like that previously characterized in other (Ca2+-Mg2+)-ATPases
Extracellular HIV-1 Tat protein induces a rapid and selective activation of protein kinase C (PKC)-α, -ε, and -ζ isoforms in PC12 cells
No full textThe addition in culture of extracellular HIV-1 Tat protein (0.1-1 nM) to PC12 cells induced a rapid increase of the bulk protein kinase C (PKC) catalytic activity. Among various PKC isoforms (alpha, beta I, beta II, delta, epsilon, eta, theta, and zeta) expressed in PC12 cells, Tat selectively stimulated alpha, epsilon, and zeta, as judged by activities in immunoprecipitates. Activation of these isoforms was suppressed by the tyrosine kinase inhibitor genistein. Moreover, PKC-zeta showed the fastest kinetics of activation in response to Tat, but PKC-alpha and PKC-epsilon showed the highest levels of activation. PKC-alpha activation was accompanied by a rise of intracellular IP3, while the PI 3-kinase inhibitors wortmannin and LY294002 suppressed PKC-epsilon activation. Taken together, these findings demonstrate that extracellular Tat shows a cytokine-like activity in PC12 cells, being able to trigger an intracellular signalling cascade which involves PKC-alpha, -epsilon, and -zeta
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
A motif-based profile scanning approach for genome-wide prediction of signaling pathways.
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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
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