1,721,019 research outputs found
The effects of stimulants and inhibitors of histamine receptors on acid secretion from guinea pig gastric fundus
No full textTwo selective H2 receptor stimulants (5-methyl-N-methylhistamine and dimaprit) so far never tested in isolated gastric preparations, were found to be strong stimulants of acid secretion from the guinea pig isolated gastric fundus. Although some differences were observed in the cumulative dose-response curves for these two agonists, the peak responses obtained were not significantly different from the maximum response to histamine. Cimetidine produced parallel displacement of the dose-response curves to the right with the maximum response unchanged, suggesting competitive antagonism on H2 receptors. The dose-response curve for histamine was not affected by the simultaneous administration of an H1 receptor agonist, 2(2-aminoethyl)thiazole, or of an H1 receptor antagonist, pyrilamine. This indicates that the action of histamine on the isolated guinea pig gastric fundus is associated exclusively with H2 receptor stimulation
Inhibitory effect of fentonium on gastric acid secretion in different laboratory animals
No full textEffects of two new pirenzepine analogs on the contractile response of the guinea-pig oesophageal muscularis mucosae to acetylcholine, bethanechol, histamine and high potassium
No full textThe guinea-pig oesophageal muscularis mucosae was used to determine the affinity for muscarinic receptors of two new tricyclic compounds, DF 545 and DF 594, which are structurally related to pirenzepine. Both acetylcholine and bethanechol induced a concentration-dependent contraction of the muscularis mucosae. This contraction was competitively antagonized by DF 545 and DF 594 over the dose range 10(-7)-10(-5) M, while at higher concentrations both antagonists caused a depression of the maximal response to the cholinomimetics. The potency of DF 545 and DF 594 appeared to be comparable to that of pirenzepine and approximately 50 times lower than that of atropine. By comparing the affinities of DF 545 and DF 594 with those of selective antagonists (methoctramine and 4-DAMP) which discriminate between M2/M3 muscarinic receptor subtypes, it emerged that pirenzepine as well as DF 545 and DF 594 might act on M3 receptors, which seem to be predominant in the guinea-pig oesophageal muscularis mucosae. McN-A-343 exhibited no agonist activity while it acted as a competitive antagonist against acetylcholine and bethanechol. None of the compounds exhibited calcium antagonist properties. DF 545 inhibited the contractile responses to histamine, but DF 594 and pirenzepine did not
R-a-methylhistamine-induced inhibition of gastric acid secretion in pylorus-ligated rats via central histamine H3 receptors
No full text
Pharmacological profile of new thioperamide derivatives at histamine peripheral H1-, H2-, H3-receptors in guinea-pig
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
- …
