1,720,982 research outputs found
Editorial: Neurological, Metabolic and Inflammatory Disorders: A Common Root in Inflammasome
No full textAntisecretory and gastroprotective activities of compounds endowed with H2 antagonistic and nitric oxide (NO) donor properties
No full textIn spite of the well recognized gastric antisecretory activity, the gastroprotective potential of histamine H-2 receptor antagonists is controversial. Most clinical studies in fact indicate that these drugs do not substantially protect the gastric mucosa from aggressive factors. Nitric oxide (NO) has been recently recognized as a fundamental mediator in gastric defence mechanisms, due to its ability to increase gastric mucosal blood flow and mucus production and to inhibit neutrophils adherence to endothelial cells. The aim of this study was to investigate the gastroprotective and H-2 receptor antagonistic activity of a series of lamtidine analogues which contain different NO-releasing moieties (furoxan, nitroxy and nitrosothioI). These compounds were tested, in comparison with related H-2 antagonists devoid of NO-donor structures, in different H-2 receptor assays and in the conscious rat against 0.6 N HCl-induced gastric lesions. All the compounds tested were able to antagonize histamine-mediated responses at cardiac and gastric H-2 receptors; however, furoxan and nitroxy derivatives were 10-fold less potent than the analogues devoid of NO-donor properties. By contrast, NO-donor compounds were more active than reference Il, antagonists as gastroprotective agents against mucosal injury induced by 0.6 N HCl. Among the different NO-donor moieties, the furoxan group conferred to the H-2 antagonist molecule the highest gastroprotective potential; this finding closely correlates with the characteristics of NO release. In conclusions, lamtidine-analogue H-2 antagonists combined with NO-donor moieties are endowed with gastric antisecretory and protective activity and could be the prototypes of a new class of anti-ulcer drugs. Finally, the furoxan NO donor group seems to be the most favourable among the different moieties tested
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
Furoxan Analogues of the Histamine H3 receptor antagonist imoproxifan and related furazan derivatives
No full textActivity of NO-releasing impromidine derivatives on histamine H2 and H3-receptors
No full textMolecular hybrids, obtained by coupling the imidazolic portion of impromidine to the nitric oxide (NO)-donor furoxan group, were synthesized. The pharmacological activity of these hybrids at histamine H2 and H3 receptors was tested on the isolated guinea pig papillary muscle and duodenum, respectively, in comparison with corresponding furazan models, devoid of NO-donor properties.
In the papillary muscle, both furoxan and the corresponding furazan models showed a positive inotropic effect, prevented by the H2-receptor antagonist famotidine. Compared to impromidine (=0.90, pD2=7.49), the efficacy of these compounds ranged between 0.40 to 0.65 and their potency was 2-3 orders of magnitude lower. Since corresponding furoxan and furazan models gave equivalent effects, mayor influences of NO on the inotropic state of the papillary muscle or on the H2 receptor functions could be excluded.
In the duodenum, the furoxan models competitively antagonized the inhibitory effect of the H3 receptor agonist R()methylhistamine on neurogenic cholinergic contractions. pA2 values of furoxan models were equivalent to, or higher than, that of impromidine, but inversely related to their ability to release NO. Accordingly, pre-treatment with the inhibitor of soluble guanylyl cylase, ODQ, enhanced the pA2 value of compound MB-898H (strong NO donor) from 6.86 to 7.66, close to the pA2 value of its furazan analogue MB-914C (7.81). These observations suggest that the furoxan group, similarly to the furazan group, may increase the H3-receptor antagonistic activity of the impromidine structure and that the NO released by furoxan hybrids may affect the interaction of such compounds with the histamine H3 receptor
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
Unsymmetrically substituted furoxans. Part 18. Smiles rearrangement in furoxan systems and in related furazans
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