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The effect of the new H2-receptor antagonist mifentidine on gastric secretion, gastric emptying and experimental gastric and duodenal ulcers in the rat: comparison with cimetidine and ranitidine.
No full textThe new H2-receptor antagonist mifentidine (DA 4577) was tested for its antisecretory and gastric motor effects in comparison with cimetidine and ranitidine. The Shay rat preparation (5 h) was used for studying gastric secretion; the gastric emptying of a liquid meal was chosen for studying gastric motility. All the three compounds inhibited acid secretion in a dose-dependent fashion. Calculated ED50s were 2.3, 12.2 and 92.8 mg X kg-1 for mifentidine, ranitidine and cimetidine, respectively. Therefore, in this animal model, mifentidine was about 40 times more potent than cimetidine and 5 times more potent than ranitidine. As far as gastric emptying is concerned, the effect of equiactive antisecretory doses (i.e. the respective ED50s calculated from the previously established dose-response curves) of all the three antagonists was completely different. Cimetidine delayed emptying rate, whereas ranitidine accelerated it and mifentidine was completely ineffective. However, at higher doses, also this compound affected emptying rate by reducing it dose-dependently. Gastric and duodenal ulcers were induced in the rat by dimaprit (100 mg X kg-1 intravenously) and cysteamine (250 mg X kg-1 subcutaneously), respectively. As far as gastric ulcer is concerned, the ED50s (the effective dose which protected 50% of the animals from lesions) were 0.23, 4.40 and 9.70 mg X kg-1 for mifentidine, ranitidine and cimetidine, respectively. As regards duodenal ulcer, the ED50 was 4.48 for mifentidine and 150.00 mg X kg-1 for ranitidine. In this animal model, the efficacy of cimetidine was very low. Therefore an ED50 could not be determined. In conclusion, results of the present investigation demonstrated that mifentidine is a potent antisecretory compound and an effective anti-ulcer agent in the rat
Effect of the new H2-receptor antagonist mifentidine on gastric acid secretion in the cat: comparison with cimetidine and ranitidine.
No full textThe effect of the H2-receptor antagonist mifentidine (DA 4577) was studied in conscious fistula cats in comparison with cimetidine and ranitidine. Two series of experiments were carried out. In the first, submaximal gastric secretion was induced by continuous intravenous infusion of dimaprit (a selective H2-agonist). Once a plateau of gastric secretion had been reached, antagonists were infused intravenously at increasing doses for 3 hr. Mifentidine, ranitidine, cimetidine or saline were administered in different days at random order. In the second set of experiments, equiactive doses (that is the respective ED50s calculated from the previously established dose-response curves) of all the compounds were infused during dimaprit-induced acid hypersecretion, in order to evaluate their duration of action. All the compounds inhibited acid secretion in a dose-dependent fashion. Calculated ED50s were 0.39 +/- 0.05, 0.49 +/- 0.04 and 10.13 +/- 0.33 mumol.kg-1.hr-1 for mifentidine, ranitidine and cimetidine respectively. After the infusion of the equiactives doses, the half-life (that is the time taken to return to 50% inhibition) was 76.4 +/- 14.7 min for mifentidine, 38.3 +/- 10.1 min for ranitidine and 33.6 +/- 2.9 min for cimetidine. These data demonstrate that mifentidine is a potent antisecretory compound with a duration of action longer than that of cimetidine and ranitidine
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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