1,721,292 research outputs found
Camostate- and caerulein-induced delay of gastric emptying in the rat: effect of CCK receptor antagonists.
No full textThe effect of camostate, a potent releaser of endogenous cholecystokinin (CCK), and of caerulein, an amphibian peptide mimicking the biological actions of CCK, as well as of selective CCK receptor antagonists on gastric emptying of liquids was studied in the rat. Oral administration of camostate (200 mg/kg with the liquid test meal preceded by the same dose 10 min before the meal) significantly delayed gastric emptying of saline, an effect which was completely blocked by previous administration of the CCKA receptor antagonist, devazepide, at a dose (1 mg/kg i.v.) unable to modify the emptying rate when administered alone. Caerulein (0.03-30 nmol/kg i.v.) also delayed the emptying rate in a dose-dependent manner, with an ID50 of 3.94 nmol/kg. The effect of the peptide was also inhibited by devazepide. The CCKB receptor antagonist, L365,260 (3R-(+)-N-(2,3-dihydro-1-methyl-2-oxo-5-phenyl-1H-1, 4-benzodiazepine-3-yl)-N'-(3-methylphenyl)-urea; 3 mg/kg i.v.), was completely unable to modify the CCK (both endogenous and exogenous)-induced delay in gastric emptying. Repeated (7 days) camostate administration did not modify the gastric motor response to endogenous CCK, thus, suggesting that adaptation did not take place. These results demonstrate that endogenous and exogenous CCK delays gastric emptying of liquids through stimulation of CCKA receptors and suggest that adaptation of the gastric motor response to CCK does not occur
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
Inhibition of pancreatic secretory and trophic response to caerulein by the H2-receptor antagonist ranitidine in the rat.
No full textThe effect of ranitidine (20 mg . kg-1) and cimetidine (50 mg . kg-1) on pancreatic secretory and trophic responses to caerulein (1 microgram . kg-1) was studied in the rat. Ranitidine or cimetidine were administered alone or combined with caerulein twice a day for 7 days. Saline-treated rats were used as controls. At the end of treatment animals were anesthetized and pancreatic juice was collected for 1 h after intravenous secretin plus CCK-PZ (8 U . kg-1). Afterwards rats were sacrificed and growth and composition of pancreatic tissue were determined. Compared with control (saline) values, volume of pancreatic juice and output of trypsin and amylase were increased by treatment with caerulein. Ranitidine, when given combined with caerulein, completely abolished the secretory response induced by the peptide, whereas it was totally ineffective when given alone. Cimetidine (alone or combined with caerulein) was always ineffective. Caerulein increased pancreatic weight, total pancreatic trypsin, amylase and RNA content. Here again ranitidine, combined with caerulein, abolished almost completely the trophic effect of caerulein on the pancreas, but when given alone it did not influence pancreatic growth and composition. Also in this case, cimetidine was completely inactive. These results suggest that ranitidine affects exocrine pancreas with an action independent of the H2-receptor blockade
Pancreatic secretory and trophic response to caerulein in rats: effect of proglumide and lorglumide.
No full textThe effect of proglumide and lorglumide, two CCK-receptor antagonists, on caerulein-induced pancreatic secretion and growth was studied in the rat. In anaesthetised animals, caerulein (1 microgram/kg) significantly increased the volume of pancreatic juice and protein output. Lorglumide (5 and 10 mg/kg), administered intraperitoneally 15 min before stimulation, reduced peptide-induced pancreatic exocrine secretion. By contrast, proglumide (100 and 400 mg/kg) was completely ineffective. In experiments dealing with the trophic effect of caerulein, both drugs were administered alone or combined with the peptide (1 microgram/kg) 3 times daily for 5 d. Saline-treated rats served as controls. At the end of the experiment, rats were sacrificed, and growth and composition of pancreatic tissue were determined. Pretreatment of the animals with either proglumide or lorglumide did not affect pancreatic size and composition. Caerulein increased the weight of the pancreas, the total pancreatic protein, trypsin, amylase, and DNA content. After pretreatment with proglumide, all these parameters were not significantly different from those obtained with caerulein alone. In contrast, when lorglumide was given together with caerulein, it significantly reduced caerulein-induced pancreatic growth and decreased enzymatic protein content of the gland. These results show that lorglumide is a much more potent and effective CCK-receptor antagonist than proglumide. Its ability to antagonize the pancreatic secretory and trophic action of a CCK-analogue (i.e. caerulein) supports the view that these physiological actions of CCK are mediated through an interaction of the hormone with specific receptors
Effect of CCK and its antagonists on gastric emptying.
No full textCholecystokinin (CCK) belongs to the group of substances known as brain-gut peptides: it functions both as a neuropeptide and a gut hormone. The peptide and its synthetic derivatives (like for instance CCK-8 and the amphibian counterpart caerulein) significantly delay emptying of gastric contents in both animals and humans. The fact that CCK, in doses mimicking postprandial plasma levels, strongly affects emptying rate suggests the peptide to be a physiologic regulator of gastric emptying. Unfortunately, clear definition of the role of CCK in the physiology of gastric motor activity has long been hampered by the lack of specific and potent non-peptide antagonists of CCK-receptors. The availability of such compounds has stimulated a broad array of investigations into the physiological actions of this hormone and examination of its putative role in certain diseases. This paper summarizes the available data concerning the effect of CCK and its antagonists on gastric emptying. The use of selective CCK-antagonists has allowed to establish that the gastric motor effect of the peptide is direct and mediated through the stimulation of CCK-A receptors. As a consequence, CCK-A antagonism results in acceleration of emptying rate under certain experimental and clinical conditions. This peculiar pharmacologic effect of CCK-A antagonists, which could be useful in the treatment of functional dyspepsia (idiopathic or diabetic), gastroparesis and gastro-esophageal reflux disease (where patients often display a delayed emptying rate of solid food) needs to be further investigated, in order to fully explore their potential as gastrokinetic drugs
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
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