1,720,971 research outputs found
Canrenone as a partial agonist at the digitalis receptor site of (Na+-K+)ATPase
No full textCanrenone, a spironolactone metabolite, was tested for its possible effects on (Na+-K+) adenosine triphosphatase (ATPase) activity [Mg++-dependent, (Na+-K+)-activated ATP phosphohydrolase (E.C.3.6.1.3) and ouabain interaction with the enzyme. Canrenone competitively antagonized the binding of [3H]ouabain to (Na+-K+)ATPase and inhibited (Na+-K+)ATPase activity. The multiple inhibition technique was used to demonstrate that canrenone is a partial inhibitor of (Na+-K+)ATPase, mutually exclusive with respect to ouabain. Comparative studies of the effects of ouabain and canrenone on potassium-dependent p-nitrophenylphosphatase activity (E.C.9.6.1.7) and potassium activation of (Na+-K+)ATPase confirmed that ouabain and canrenone interacted with the same receptor site. The finding that canrenone is a partial agonist may explain the results of previous in vivo studies showing that spironolactone and the allied drug to potassium conrenoate have either a positive inotropic action or an antagonistic effect against digitalis toxicity
Reduction by eparin of basal and glucose-induced increase in proteolytic activity of trypsin.
No full textHeparin-induced structural and functional alterations of bovine trypsin.
No full textTo investigate the mechanism whereby heparin can modulate the activity of serine proteinases, bovine trypsin was chosen as reference and treated with heparin at 10, 100 and 200 μg/ml, in buffer solvents, with and without incubation at 37°C. Heparin caused rapid, buffer- and pH-dependent decrease in trypsin solubility due to the generation of insoluble fragments from proteinase. Desalting treatments variously restored solubility by removing insoluble material. UV absorption and fluorescence emission spectra revealed significant heparin-induced conformational alterations in the trypsin molecule, the maximal effect being apparent at a proteinase-to-heparin molar ratio ranging from 1.6 to 1.0. The involvement of the catalytic sites of trypsin by heparin was further confirmed by the significant reduction in the difference absorption spectra of proflavine. Both proteolytic and esterolytic activities of trypsin were shown to be markedly decreased by heparin, especially after 5 h incubation at 37°C. However, when the proteolytic and esterolytic activities of trypsin were measured on fresh solutions not submitted to desalting treatments, variable activation instead of inhibition of both activities was observed in the presence of heparin, this effect waning spontaneously in time or after desalting treatment. The paradoxical increase in functional activities was not inhibited by soybean trypsin inhibitor and was accompanied by denaturation and fragmentation of the proteinase as demonstrated by spectroscopic analyses and SDS-PAGE of fresh solutions. The results obtained indicate that heparin causes a rapid, time- and temperature-dependent conformational alteration of trypsin with irreversible denaturation and degradation of the proteinase. The underlying mechanism appears to be heparin-catalyzed oxidative degradation of trypsin due to liberation of oxygen radicals which are also responsible for the temporary increase in catalytic functions
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
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