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Biomedical subjects

A Ribet

Publications and source records attributed to A Ribet.

At least 91 records · Page 5Linked to original sources
PubMed1982

The decrease of the non secretory phospholipase A in rat pancreas during a chronic alcohol intoxication.

It is known that ethanol induces morphological lesions in the exocrine pancreas of man and of experimental animals. We showed recently that ethanol is metabolized by the rat pancreas. It has also been demonstrated that ethanol acts on the lipid metabolism of the pancreas by stimulating the lipid biosynthesis and by inhibiting fatty acids oxidation. We recently characterised a non secretory phospholipase A in the rat pancreas, probably involved in the intracellular phospholipid turnover. The actions of chronic alcoholic intoxication on the level of this enzyme is investigated in this paper. The ethanol intoxication was prolonged for two years and resulted in a progressive decrease in the level of the pancreatic non secretory phospholipase (p less than 0.01). This result confirms the chronic metabolic modifications induced by alcohol on the pancreas and emphasizes its metabolic participation in chronic alcoholic pancreatitis.

Alcoholism↗
PubMed1981

Experimental study of laser photocoagulation in the treatment of bleeding canine gastric ulcers.

We report experimental results obtained by laser photocoagulation on hemorrhagic lesions induced in dogs. The aims of this study were 1) to evaluate the real efficiency of the YAG laser to ensure hemostasis of briskly bleeding lesions; 2) to determine the minimum energy density necessary to ensure hemostasis; 3) to assess the damage depth inside the gastric wall after photocoagulation; 4) to compare reepithelialization of treated ulcers with that of control ulcers; 5) to evaluate the safety margin for the clinical use of the YAG laser.

Animals↗
PubMed1981

Gd(-) Muret and gd(-) Colomiers, two new variants of glucose-6-phosphate dehydrogenase associated with favism.

Two males subjects are described with hitherto undescribed glucose-6-phosphate dehydrogenase (G6PD) variants. The first is of French ancestry, the second of Sicilian extraction. Each subject suffered from acute hemolytic anemia following ingestion of broad beans (Vicia fava). In both cases the hemolytic crisis occurred in a late period of life (29 and 58 years). No previous hemolytic crisis was recorded. The electrophoretic and kinetic properties of the mutant enzymes examined after purification from the red cells allowed each to be distinguished from other G6PD variants reported until now. The first variant was named Gd(-) Muret, the other Gd(-) Colomiers.

Adult↗
PubMed1981

Effect of pancreatic duct ligation on the hamster intestinal mucosa. Variation of several hydrolases.

Hamster intestinal hydrolase activities were studied after pancreatic duct ligation for periods of 5, 7, 10, 15 and 30 days. From the 7th to the 10th day, maltase and sucrase were significantly increased in the jejunoileum. Higher levels were observed on day 7 in the duodenum for all the brush-border enzyme activities (maltase, sucrase, aminopeptidase, alkaline phosphatase). Intestinal lysozyme significantly increased from the 5th to the 15th day with a maximal level at the 7th day. The increased levels of brush-border enzymes observed here are not in accordance with our description of villous atrophy after pancreatic duct ligation in the hamster. On the other hand, the important increase in lysozyme activity is in good agreement with hypertrophy and hyperplasia of the Paneth cells which we observed during our morphological study. The morphological and biochemical findings on hamster small intestine confirm the effects of exocrine pancreatic secretion both on differentiation and on enzymatic levels of the mucosa. Besides, this experiment agrees with the direct desorbing action of the pancreatic juice on the brush border and suggests another hypothetical mechanism, still worth being investigated, to explain increased brush-border activities in the duodenum and increased levels of lysozyme in the jejunoileum.

Alkaline Phosphatase↗
PubMed1981

Action of secretagogues on amylase release from dog pancreatic acini.

This work describes a new preparation of dog pancreatic acini which were used to study amylase release in response to various secretagogues. Neither secretin nor vasoactive intestinal peptide stimulated amylase release from acini. Caerulein, carbachol and human synthetic gastrin G17 stimulated amylase release with the same efficacy, but with different potencies. Bombesin nonapeptide did not show any evidence of a direct stimulatory effect on amylase release. These species-related peculiarities stress the necessity of using the same species when comparing pancreatic cell behaviour in vivo and in vitro.

Amylases↗
PubMed1981

Effects of somatostatin-14 and somatostatin-28 on bombesin-stimulated release of gastrin, insulin, and glucagon in the dog.

The effects of somatostatin-14 (S14) and somatostatin-28 (S28), a novel intestinal peptide containing somatostatin tetradecapeptide in its C-terminal position, on the bombesin-stimulated release of gastrin, insulin, and glucagon were tested. On iv infusion of bombesin, the increase in the level of glucagon was seen to be twice that of gastrin, and the insulin increase was 8 times that of gastrin. Plasma concentrations of somatostatin were not modified. S14 and S28 inhibited the release of gastrin, insulin, and glucagon; insulin release was inhibited most effectively, with glucagon release next, and gastrin release least inhibited. Based on the exogenous dose needed to produce equal effects, S28 was more potent than S14 on a molar basis, but based on the plasma concentrations needed to produce equal effects, S14 and S28 were equipotent.

Animals↗
PubMed1981

[Total synthesis of somatostatin-28 (author's transl)].

The total synthesis of the octacosapeptide corresponding to the proposed primary structure of porcine somatostatin-28 is described. The synthesis has been performed using a protection scheme of maximum selectivity (acid labile side chain protection based on tert-butyl alcohol and 1-adamantol derived protecting groups in combination with the S-tert-butylthio group for reversible and selective blocking of the cysteine thiol functions and the 2-nitrophenylthio group for the temporary protection of the alpha-amino functions of intermediate segments) and of carefully selected fragments. Upon assembly in sequence order of the four suitably protected fragments related to sequences 18-28, 15-17, 8-14 and 1-7, the asymmetric disulfides were reduced by exposure of the fully protected octacosapeptide to phosphines. Subsequently, the final deprotection was performed with trifluoroacetic acid and the resulting dihydrosomatostatin-28 was then converted by air oxidation into the "cyclic peptide". Gel filtration on Biogel P-6 and ion-exchange chromatography on Biogel CM-2 produced somatostatin-28 at a high degree of purity. Comparative analysis of the synthetic and natural product by means of chromatographic, immunological and biological assays confirmed the structure proposed for this putative precursor of somatostatin-14.

Amino Acid Sequence↗
PubMed1981

Long term effects of H2-receptor antagonists (cimetidine and ranitidine) on the human gastric and duodenal mucosa.

Cytological effects of two H2-receptor antagonists on the gastric and duodenal mucosa were studied during therapy of active duodenal ulcer (D.U.) in man. After endoscopic diagnosis (day 0), subjects were treated with cimetidine or ranitidine and re-examined on day 30. Only subjects with healed D.U. on day 30 were retained in this study. Gastric, pyloric and duodenal endoscopic biopsies were taken and treated for further morphometrical analysis both by light and electron microscopy. The use of the immunoperoxidase technique allowed evaluation of G and D cell populations. Kinetic parameters in proliferative zones were measured after in vitro incubation of biopsies with 3H-thymidine. No differences could be seen between the two H2-receptor antagonists. Increase of tubulovesicles and decrease of canaliculi in parietal cells are closely related to the inhibitory effect of these drugs on acid secretion. However secretory capacities of parietal cells are preserved since the whole membrane (tubulovesicle + canaliculi surface) remained constant. The collapsed aspect of the tubulovesicles on day 30 and the presence of connections between the tubulovesicle membrane, with both vesicle and canaliculi membrane, could support the theory of osmotic membrane expansion during parietal cell acid secretion. H2-receptor antagonists have been shown to be trophic in duodenal mucosa: both villi and microvilli area are increased. Confirming these findings, the proliferative compartment in the intestinal crypts was shown to be enlarged. No variation of G cell number could be seen in the antral mucosa; clear intracytoplasmic granules were increased in D.U. on day 0 but were not further modified on day 30. Somatostatin labelling index decreased. These last findings associated with the lack of G cell variations, suggest the presence of a possible paracrine modulation in the gastric and duodenal mucosa.

Biopsy↗
PubMed1981

A cooperative study on the detection of colorectal cancer and polyps in France.

Systematic investigations testing for the presence of polyps and cancers of the large bowel were conducted in a population of 1,369 inpatients and outpatients, aged 45-70 years, in eight university departments of gastroenterology or abdominal surgery (Toulouse, Dijon, Paris, Marseille, and Strasbourg). Double-contrast barium enema and proctosigmoidoscopy examinations were carried out in all cases, whereas total coloscopy was performed only in the case of detected tumors. A questionnaire including 233 parameters (age, sex, family, and personal history and symptoms) was completed for each patient. A total of 414 lesions were detected in 252 patients, including 245 adenomatous or villous polyps, 8 transformed polyps, and 30 carcinomas; 3 of 4 lesions were located in the rectum or sigmoid. Cancer or adenomatous or villous polyps were found in 13% of the patients. The prevalence of these lesions in the population studied was increased in patients with rectorrhagia (19%) or with a personal history of surgery for colorectal cancer or polyp (23%). In the patients without rectorrhagia or a history of intestinal tumor, the incidence was 9.7%. It was significantly increased in males and patients more than 50 year old. The efficacy of proctosigmoidoscopy and double-contrast barium enema was compared in 909 patients. Sensitivity and specificity were, respectively, 35% and 99% for endoscopy, 96% and 94% for radiology.

Aged↗