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Effect of bombesin on glucose-induced insulin release in humans.
No full textThe effect of bombesin on basal and glucose-stimulated insulin release was studied in male healthy volunteers. Glucose was administered by oral, intravenous or intraduodenal route during saline or bombesin infusion (5 ng/kg/min for 60 min). The peptide had no significant effect on basal levels of glucose and insulin. However, during its administration, the insulin response and the expected rise in blood glucose after oral glucose load (50 g) were strongly inhibited, and the gastric emptying of liquids was significantly delayed. On the contrary, the insulin response to intravenous glucose (20 g) was significantly increased by bombesin without changes in plasma glucose levels. Finally, when glucose was infused into the duodenum, thus bypassing the stomach, the insulin response was significantly increased by the peptide. In this case, too, plasma glucose levels after glucose load were virtually identical during either bombesin or saline infusion. These data clearly demonstrate that the direct effect of bombesin on insulin release is stimulatory and suggest that the inhibitory effect observed after oral glucose is connected with the action of the peptide on gastric emptying, the delay of which slows the entry of glucose into the small bowel
Transmucosal potential difference as an index of esophageal mucosal integrity.
No full textAll the epithelia lining the gastrointestinal (GI) tract, including that of the esophagus, exhibit a transmucosal electrical potential difference (PD). The luminal surface of the GI mucosa is indeed electrically negative when compared with the serosal one. Although it was initially felt that the body of the esophagus exhibits a PD near 0 or slightly positive, recent studies, using parenteral reference electrodes, have shown a negative PD of around -15 mV. Measurement of esophageal PD has been mainly used to locate both the lower and the upper esophageal sphincters but very rarely to evaluate esophageal mucosal integrity in clinical settings, most probably due to the difficulties encountered during measurement of mucosal PD. Reliable techniques to measure esophageal PD simultaneously with esophageal pressure or mucosal pH are now available. Application of these recently developed methodologies showed that measurement of esophageal PD during either manometry or endoscopy provides meaningful information about mucosal integrity. Indeed, tissue injury, either neoplastic of inflammatory, usually results in a less negative PD. In contrast, an abnormally high negative PD is very often observed in patients with columnar-lined lower esophagus. In patients with microscopic reflux esophagitis, PD exhibits less negative values which are significantly correlated with the degree of the mucosal damage. Normalization of the altered PD after either medical or surgical treatment makes it an additional parameter to evaluate the effect of a given therapy
Opposite effects of bombesin on insulin and gastrin response to food in humans
No full textSUMMARY The effect of bombesin on insulin and gastrin response to a standard labelled meal was studied in eight healthy male volunteers. The gastric emptying of solids was simultaneously evaluated. During intravenous infusion of the peptide (5 ng/kg/min) the insulin release after eating was greatly reduced whereas food stimulated gastrin release was significantly enhanced. Both effects of bombesin are likely to be connected with the marked inhibition of gastric emptying induced by the peptide. Bombesin is a frog skin tetradecapeptide which has been found to have similar immunologically charac-tensed counterparts in mammalian gut. 1-3 An heptacosapeptide has been isolated from porcine non-antral gastric tissue: the so called gastrin releas-ing peptide (GRP).4 The homology of its C-terminal decapeptide with C-terminal decapeptide of bombesin is impressive. As a consequence, both these peptides have the same spectrum of biologica
Effects of bombesin on gastric emptying of solids in normal and antrectomized subjects: evidence for an action at the distal stomach
No full textThe effect of bombesin on gastric emptying of solids in man.
No full textIntravenous infusion of bombesin (5 ng.kg(-1). min(-1) significantly delayed gastric emptying of solids in man. The gastrin response to meal increased following administration of the peptide; however no correlation was found between the difference in gastrin response (to meal alone and to meal plus bombesin) and the degree of delay in emptying. In addition the behavior of intragastric pH after eating was not modified by bombesin infusion. All of these data suggest a direct effect of the peptide on gastric emptying, which was probably connected with the strong contraction of the antrum and pylorus observed in this and in previous investigations
Different effects of bombesin on glucose- and tolbutamide-induced insulin release in man.
No full text1. The effect of bombesin, a neurogastrointestinal peptide, on basal and stimulated insulin release was studied in man. 2. Two different stimuli were used, hyperglycaemic (20 g glucose) and hypoglycaemic (1 g tolbutamide). They were injected intravenously to two groups of male healthy volunteers during saline or bombesin (5 ng kg-1 min-1 for 60 min) infusion. 3. The peptide had no significant effect on basal levels of glucose and insulin. However, the insulin response to intravenous glucose was strongly potentiated by bombesin, the integrated insulin response being 2.23 +/- 0.59 mu ml-1 . 90 min and 0.98 +/- 0.19 mu ml-1 . 90 min during infusion of bombesin and saline, respectively (P less than 0.05). The behaviour of plasma glucose was not significantly modified by the peptide. Indeed, the glucose disappearance rate (K of Conard, mg min 10(-2)) changed from 2.5 +/- 0.3 during saline to 2.4 +/- 0.4 during bombesin infusion. 4. When the hypoglycaemic stimulus (i.e. tolbutamide) was used, no effect of the peptide on insulin release could be detected. Here again, the drop in plasma glucose (expressed as Marigo's coefficient) was not affected by the peptide, with a value of 92.8 +/- 12.6 and 84.0 +/- 10.9 during bombesin and saline administration. 5. These data therefore show that, at normal or low blood glucose levels, the dose of bombesin used is unable to modify insulin release and suggest that this peptide might be regarded as a glucose-dependent insulinotropic peptide
Inhibition of gastric emptying by bombesin in man.
No full textBombesin, administered by intravenous infusion (5 ng . kg-1 . min-1) for 60 min, significantly delayed gastric emptying of solids in man and strongly potentiated the gastrin response to food. However, no correlation was found between the difference in the integrated gastrin response (to meal and to meal plus bombesin) and the degree of delay in emptying. The effect of the peptide is most likely connected with the strong contraction of the gastroduodenal junction pinpointed in previous investigations
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
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