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Biomedical subjects

M V Singer

Publications and source records attributed to M V Singer.

At least 109 records · Page 6Linked to original sources
PubMed1991

Action of beer and its ingredients on gastric acid secretion and release of gastrin in humans.

The intragastric action of beer and its known ingredients before and after fermentation on gastric acid secretion and release of gastrin was studied in healthy humans. None of 11 tested ingredients of fermented beer (2 x 500 mL, pH 5.5, given either alone or in combination) or hop extract had any significant effect. Finished beer (6 weeks old) and new beer were potent stimuli of acid output, causing 93% and 76% of the incremental maximal acid output in response to pentagastrin (6 micrograms/kg SC), respectively. Before the addition of yeast, preproducts of beer were considerably less potent. Thus, first and finished wort caused only a minor acid response which was 48% and 46% of maximal acid output. Foreign fermentation in first and finished wort is presumably the reason for the stimulatory action because glucose solutions in concentrations (11.5% wt/vol) seen in wort did not stimulate acid secretion. However, glucose solutions to which yeast was added, resulting in fermentation, were as potent stimuli of acid secretion as beer. Lyophilization of beer at pH 11.0 and dialysis (cutoff mol wt, 1000) removed the stimulatory substances. The plasma gastrin responses paralleled the gastric acid response to the different stimulants. It was concluded that (a) the addition of yeast to finished wort and the following alcoholic fermentation are the essential steps for the stimulatory action of beer on gastric acid secretion and release of gastrin; (b) carbohydrate metabolites with a molecular weight of less than 1000 are the acid-stimulatory agents in fermented beer; and (c) gastrin is the mediator of the stimulation of acid secretion because all substances that had a potent acid-stimulatory action also were potent stimuli of gastrin release.

Adult↗
PubMed1991

Intrinsic pancreatic nerves after mechanical denervation of the extrinsic pancreatic nerves in dogs.

Little is known about the influence of cutting the extrinsic pancreatic nerves on the morphology and function of the intrapancreatic nerves in dogs. For this reason, intrapancreatic nerves of mongrel dogs were studied, using electron microscopy and immunohistochemistry, after truncal vagotomy, after celiac and superior mesenteric ganglionectomy, and after a combination of both operations, i.e., removing all extrinsic nerves of the pancreas. Dogs with intact extrinsic and intrinsic pancreatic nerves served as controls. Studies were performed 1-2 weeks and up to 5 months after one or both denervation procedures. For immunohistochemical and electron microscopic studies the animals were perfused with glutaraldehyde-formaldehyde-picric acid solution and the tissue was embedded in Epon or paraffin. Both immunohistochemical and electron microscopic studies revealed that signs of degenerating intrapancreatic nerves occurred only in the early phase (up to 30 days) after operation. After 60 days, hypertrophy of pancreatic nerve fibers was observed. The most striking finding was that the integrity of the intrapancreatic ganglia and nerves was almost preserved after complete extrinsic denervation. In controls there was a strong intrapancreatic innervation with vasoactive intestinal polypeptide (VIP) and peptide histidine isoleucine (PHI), substance P (SP), and neuropeptide Y (NPY) nerves. SP and NPY-nerves significantly decreased after the different denervation procedures, but the other peptidergic nerves were not altered by truncal vagotomy, ganglionectomy, or the combination of both procedures. We conclude that the dog pancreas contains extensive intrinsic peptidergic nerves, which, with the exception of SP and NPY-nerves, are greatly independent of the integrity of the extrinsic nerves.

Animals↗
PubMed1991

Hormonal control of pancreatic secretion by intrajejunal HCl: studies in dogs with an autotransplanted entire jejunoileum.

To elucidate the role of hormones in the control of pancreatic secretion, we developed, in seven dogs, a model of total extrinsic denervation of the jejunoileum by autotransplanting this segment of bowel. A Thomas-like cannula was placed into the stomach, the duodenum (to collect pure pancreatic juice), and the proximal part of the jejunum. Thus, intestinal stimulants could only stimulate the pancreas via release of humoral (= hormonal) mediators. Seven control dogs received only the three fistulas. After recovery, dose-response curves of pancreatic bicarbonate and protein response to perfusion of the extrinsically denervated or innervated jejunoileum with HCl (1.5 to 48 mmol h-1) were performed with and without atropine (14 nmol kg-1 h-1 i.v.). Plasma levels of secretin were determined by radioimmunoassay. The maximal bicarbonate output occurred in response to 24 mmol h-1 of HCl and was significantly (p less than 0.05) higher in intact as compared to denervated animals. Atropine only significantly depressed the bicarbonate response to HCl in dogs with a denervated jejunoileum. HCl caused a dose-dependent increase in plasma levels of secretin, which was not altered by denervation and/or atropine. Irrespective of the innervation of the small bowel, pancreatic protein output was only significantly stimulated above basal when high loads (12-48 mmol h-1) of HCl were given. Atropine significantly reduced these responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effect of the cholecystokinin-receptor antagonist lorglumide on pancreatic enzyme secretion stimulated by bombesin, food, and caerulein, giving similar plasma cholecystokinin concentrations in the dog.

This study was undertaken to determine the role of cholecystokinin in pancreatic enzyme secretion stimulated by bombesin and a meal by (a) comparing the pancreatic enzyme output during bombesin infusion and after a meal to output during caerulein infusion and (b) comparing the inhibitory effect of the cholecystokinin-receptor antagonist lorglumide (CR-1409) on enzyme output in response to bombesin and food with the response to caerulein. Bombesin (90 pmol/kg per h) and caerulein (30 pmol/kg per h) were infused into seven dogs in doses giving similar plasma cholecystokinin peak increments as a meal (mean (SEM) 6.8 (0.8), 6.3 (1.2), and 5.7 (0.8) pM, respectively), together with either saline or 2 mg/kg per h of lorglumide. A background infusion of synthetic secretin 20.5 pmol/kg per h was given in each experiment. In addition, gastric acid secretion was determined in the experiments with bombesin and caerulein infusion. Pancreatic protein responses to bombesin (1231 (247) mg/h) and food (1430 (220) mg/h) were similar to the responses to caerulein (1249 (201) mg/h). Lorglumide inhibited pancreatic protein output during stimulation with bombesin by 60%, after the meal by 45%, and during caerulein infusion by 68%. Pancreatic bicarbonate output by bombesin, caerulein, and food was inhibited by lorglumide by 28%, 40%, and 38%, respectively. In contrast, lorglumide significantly increased gastric acid secretion from 1.12 to 7.98 mmol/h during bombesin infusion and from 0.52 to 7.62 mmol/h during caerulein infusion. In conclusion, cholecystokinin plays an important part in the stimulation of pancreatic enzyme secretion by bombesin and a meal in conscious dogs and it is involved in the regulation of gastric acid during stimulation by infusions of caerulein and bombesin.

Animals↗
PubMed1991

Influence of the M1-receptor antagonists telenzepine and pirenzepine on pancreatic secretory response to intraduodenal tryptophan in dogs.

In conscious dogs with gastric and pancreatic fistulas, we compared the action of different doses of telenzepine (ranging from 9 to 243 nmol kg-1 h-1 i.v.) and pirenzepine (ranging from 43 to 1,170 nmol kg-1 h-1 i.v.) on the pancreatic secretory response to graded loads of intraduodenal infusions of tryptophan, given with a secretin background. Both, telenzepine and pirenzepine caused an overall significant inhibition of the cumulative incremental pancreatic protein output by 65.8 and 66.8%, respectively. The pancreatic bicarbonate output was also reduced by 38.3 and 40.5%, respectively, but the effect did not reach statistical significance. The inhibitory potency of the effective doses of telenzepine or pirenzepine did not differ significantly. Only the highest doses of telenzepine (243 nmol kg-1 h-1 i.v.) and of pirenzepine (1,170 nmol kg-1 h-1 i.v.) significantly increased heart rate from 59.9 +/- 3.4 to 63.1 +/- 4.5 bpm, respectively. These findings indicate that (1) in the intact animal, the M1-receptor antagonists telenzepine and pirenzepine are capable of inhibiting pancreatic bicarbonate and protein output in response to intraduodenal tryptophan with secretin background, and (2) telenzepine is 4.7 times more potent than pirenzepine.

Animals↗
PubMed1991

Cytoprotective and dose-dependent inhibitory effects of prostaglandin E1 on rat pancreas treated with ciclosporin A.

The prostaglandin E1 analogue rioprostil protects the pancreas from the noxious effect of ciclosporin A (CsA). To determine whether this cytoprotective action of rioprostil is dependent on or independent of inhibitory effects on pancreatic exocrine and endocrine secretion we studied the effect of different doses of rioprostil on pancreatic exocrine and endocrine secretions in the presence or absence of CsA. Rats received either CsA at a dose of 10 mg/kg body weight by tube feeding once in the morning, rioprostil at linearly increasing doses from 1.8 to 120 micrograms/kg body weight subcutaneously twice daily, a combination of both substances or NaCl. After 8 treatment days, the animals were operated on, and the pancreas isolated and arterially perfused. Insulin secretion was determined after stimulation with glucose, and amylase secretion after stimulation with CCK-8. Insulin and amylase secretion were significantly impaired by CsA. Rioprostil at doses of 1.8, 3.6 and 7.5 micrograms/kg body weight had no significant effect on insulin secretion in the absence of CsA but significantly improved insulin secretion in the presence of CsA. Higher doses of rioprostil significantly inhibited insulin secretion both in the presence or absence of CsA. Amylase secretion was not influenced by rioprostil at doses up to 15 micrograms/kg body weight but improved significantly amylase secretion in the presence of CsA. CsA blood and pancreatic tissue levels were not influenced by rioprostil at doses up to 120 micrograms/kb body weight. We conclude that the cytoprotective effect of the prostaglandin E1 analogue rioprostil against the noxious effect of CsA is dose dependent and is not related to its inhibitory action on endocrine and exocrine pancreatic secretion.

Amylases↗
PubMed1990

Mental stress and gastric acid secretion. Do personality traits influence the response?

In 14 healthy male volunteers, we studied the influence of acute mental (= psychological) stress induced by performing mental arithmetic and solving anagrams against a financial reward on endogenously stimulated gastric acid output. Personality factors were determined by the Personality Research Form. Acute mental stress significantly (P less than 0.05) increased systolic blood pressure (+8.9 +/- 2.0 mm Hg +/- SEM) and heart rate (+5.3 +/- 1.6 beats/min). The mean gastric acid output during the mental stress period (17.9 +/- 2.7 mmol/32 min) did not significantly differ from pre- (16.9 +/- 2.3 mmol/32 min) and poststress (18.1 +/- 2.2 mmol/32 min) values. However, detailed analysis revealed that mental stress induced contrary changes of gastric acid output in different subjects. About half the individuals reacted with a decrease (up to 60%) and the other half with an increase (up to 60%) in acid output. In some individuals the changes of gastric acid output were very small. By multiple correlations, impulsivity was identified as the personality trait with the highest correlation coefficient (r = 0.82) with changes of gastric acid output during the acute mental stress period. During the mental stress period, gastric acid output increased in subjects with high scores on the impulsivity scale, but significantly decreased in those with low scores. We conclude that (1) there is a great individual variability in gastric acid response to acute mental stress, and (2) this variability may be partly attributed to differences in personality traits.

Adult↗
PubMed1990

Role of cholecystokinin in bombesin- and meal-stimulated pancreatic polypeptide secretion in dogs.

This study was undertaken to delineate the role of cholecystokinin (CCK) in bombesin- and meal-stimulated pancreatic polypeptide (PP) secretion in seven conscious dogs by studying: (1) the stimulatory effect of similar plasma levels of CCK induced by a meal and infusions of bombesin and the synthetic CCK analog cerulein on plasma PP, and (2) the inhibition of PP secretion by the CCK-receptor antagonist CR-1409 during these three stimuli. The stimulation of PP secretion during bombesin (11.0 +/- 1.6 nM/hr) and after the meal (8.9 +/- 2.0 nM/hr) were significantly (P less than 0.05) greater than during infusion of the CCK analog cerulein (2.7 +/- 0.4 nM/hr). CR-1409 significantly inhibited the bombesin- and meal-stimulated PP secretion to 2.0 +/- 0.4 nM/hr (81%; P less than 0.05) and 3.1 +/- 1.2 nM/hr (47%; P less than 0.05), respectively, while the cerulein-stimulated PP release was almost abolished to 0.2 +/- 0.1 nM/hr (93%; P less than 0.05) by the drug. These findings point to an important role for CCK in the regulation of bombesin- and meal-stimulated PP secretion.

Animals↗