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Biomedical subjects

A Ribet

Publications and source records attributed to A Ribet.

At least 55 records · Page 3Linked to original sources
PubMed1986

Studies on human pancreatic acini: action of secretagogues on amylase release and cellular cyclic AMP accumulation.

A technique for preparing a suspension of dispersed functional acini from human pancreas has been developed. The changes in pancreatic enzyme secretion and accumulation of cellular cyclic AMP caused by various secretagogues have been studied. Ca2+-mobilizing agents stimulated amylase release from human pancreatic acini. The relative potencies with which secretagogues increased amylase release were as follows: gastrin-releasing peptide's potency (Ec50, 0.1 +/- 0.01 nM) was greater than bombesin 14's (Ec50, 0.2 +/- 0.01 nM), which was greater than litorin's (Ec50, 0.6 +/- 0.18 nM), which was greater than bombesin 9's (Ec50, 6 +/- 0.1 nM). For CCK-peptides, the relative potencies were as follows: CCK-39's potency (Ec50, 0.28 +/- 0.15 microM) was equal to cerulein's (Ec50, 0.3 +/- 0.07 microM). Both of these potencies were greater than CCK-8's (Ec50, 1.6 +/- 0.1 microM), which was greater than that of CCK-4. Carbamyl choline was poorly potent (Ec50 greater than 1 mM). The 12-O-tetradecanoylphorbol-13-acetate (TPA) was active from 0.1 nM to 0.1 microM. Neither secretin nor VIP increased amylase release from human pancreatic acini but they did cause an accumulation of cellular cyclic AMP, secretin (Ec50, 0.5 +/- 0.2 nM) being more potent than VIP.

Amylases↗
PubMed1986

[Treatment of rectal cancer with the neodymium-YAG laser].

Fifty-two non-surgical patients presenting rectal carcinoma were treated initially with palliative laser Nd-YAG. Their mean age was 79 years (49-92). Thirty patients had a severe diarrheic syndrome, associated with tenesmus in 27 cases; 20 patients had repeated hematochezia (5 presenting diarrhea as well); 6 had obstructive signs and one was symptom-free. Thirty lesions were less than 6 cm in size, 12 were between 7 and 10 cm and 10 were greater than 10 cm. Twenty-two lesions were circumferential. During the study period, 444 laser sessions were performed (mean 8.5/patient). Bleeding was stopped in all cases during the first session. Improvement of the diarrheic syndrome, obtained in 24 of the 30 patients, was correlated with the reduction of tumor volume. Tenesmus disappeared after 1 or 2 sessions, regardless of whether the tumor was destroyed or not. Failure was observed in 6 patients with lesions larger than 10 cm. Colostomy was avoided in 4 of the 6 obstructed patients. Negative biopsies were repeatedly obtained after mucosal repair in 9 patients with small lesions (less than 6 cm). Mean follow-up is now 8.2 months for the patients still alive. Complications were: 2 cicatricial stenosis and 3 hemorrhages (one required blood transfusion). Laser Nd-YAG allows palliative but conservative and effective treatment for rectal cancers. Although complete destruction is possible for small lesions, indications with curative intent are currently limited to patients with major contraindications to surgery.

Adenocarcinoma↗
PubMed1985

The amiloride sensitive Na+/H+ antiport in guinea pig pancreatic acini. Characterization and stimulation by caerulein.

Amiloride and analogs decrease the initial rate of 22Na+ uptake by dispersed acini from guinea pig pancreas in a dose-dependent manner. The initial rate of amiloride-sensitive 22Na+ uptake depends on external Na+ and H+ concentrations and on internal pH. These results provide evidence for the existence of a Na+/H+ antiport in pancreatic acinar cells. Caerulein, a cholecystokinin analog, stimulates the activity of the Na+/H+ antiport.

Amiloride↗
PubMed1985

Tumor promoter inhibition of cellular binding of somatostatin.

Tumor promoting phorbol esters inhibited the binding of 125I-[Tyr11] somatostatin to isolated acinar cells from guinea-pig pancreas. Maximal inhibition reached 69.7 +/- 5% at 1 microM TPA. Receptor affinity was decreased by 2.5-fold without change in binding capacity. The ability of TPA in inhibiting somatostatin binding was decreased in 30 nM Ca2+ medium, abolished at 4 degrees C or in a membrane preparation. The effect of caerulein, a secretagogue which also caused loss of binding, and that of TPA were not additive. We concluded that TPA inhibits somatostatin binding not by binding directly at the active site of somatostatin receptor. TPA may act at a later point than caerulein via a similar pathway to modulate somatostatin receptor affinity.

Amylases↗
PubMed1985

Long-term comparative effect of cholecystokinin and gastrin on mouse stomach, antrum, intestine, and exocrine pancreas.

Mice were injected three times a day for 12 days with 300 micrograms/kg body weight of gastrin G17 or 37.5 Ivy dog U/kg body weight of CCK or saline. Other mice were also injected four times an hr for 1 hr with 7.5 micrograms/kg of gastrin, nine Ivy dog U/kg of CCK or saline; 1 hr before killing, they were injected with tritiated thymidine to evaluate the labelling indices in peptic, antral, duodenal, jejunal, and ileal mucosae. Four hours after the first injection of the two peptides, the peptic labelling indices increased while those of intestinal mucosa increased 8 hr after these injections. Long-term injections of CCK had a trophic effect on secretory cells of the digestive tract: the number of gastric zymogenic cells, Paneth cells, and the mucous cells of Brünner glands were hypertrophied. The pepsin, amylase, chymotrypsin, and lysozyme activities increased in stomach, exocrine pancreas, and intestine, respectively. Neither parietal cells nor intestinal enterocytes and hydrolase activities were affected. The trophic effect of long-term injections of gastrin is confirmed on parietal cells and exocrine pancreatic parenchyma and is demonstrated in Paneth cells. Confirming cytological results, pancreatic lipase and amylase activities and intestinal lysozyme activity were increased after gastrin. Although CCK and gastrin have a structural analogy, these two peptides did not affect the same cellular types. A specific action of CCK on the main secretory cells of the digestive mucosa is demonstrated.

Amylases↗
PubMed1985

Long-term effect of somatostatin 14 on mouse stomach, antrum, intestine and exocrine pancreas.

Mice were injected 3 times a day for 12 days with 8 micrograms/kg of somatostatin 14 which caused a hypoplasia of parietal and goblet cells, a hypotrophy and hypofunctionality of pancreatic acinar cells with a decrease in lipase and chymotrypsin activities, a decrease in the secretory fuction of the Brunner gland and in the number of dark granules of G cells. Neither villous and microvillous areas nor brush border hydrolase activities were affected. The number of peptic cells and Paneth cells increase as the level of pepsin and lysozyme. Mice were injected 4 times per hour with 2 micrograms/kg of somatostatin. 2 h after the first injection of somatostatin and 90 min after a single injection of tritiated thymidine, fundic, antral, jejunal and ileal labelling indexes strongly decrease (maximal effect in ileum). The inhibitory effect of somatostatin on the digestive epithelial cell proliferation compared to its long-term action only directed on specific cell types evokes probable compensatory mechanisms induced to maintain the equilibrium of the digestive epithelia.

Animals↗
PubMed1985

Comparative study of histological and kinetic variations of the digestive mucosa and pancreatic parenchyma after hypophysectomy in the rat. Light and electron microscopic study.

Variations of the pancreatic parenchyma, the gastric mucosa and the intestinal mucosa were studied in adult male Wistar rats on day 8 and 15 after hypophysectomy. All results were compared with those obtained in pair-fed control rats. Hypophysectomy affected small intestine as well as gastric mucosa. Hypotrophy was observed on day 8 as most of the morphological parameters reached the maximal decrease. By contrast, hypoplasy occurred on day 15, when the labeling index (LI) decreased significantly. In the intestine, however, a decrease of the LI was observed only for the upper proliferative cells of the crypts. In the gastric mucosa, the LI was reduced only in the proliferative zone containing progenitor cells (isthmic region). Consequently, the cell differentiation is not similarly affected on all levels of the digestive tract.

Animals↗
PubMed1985

[Presence of hormonal polypeptides in the pure pancreatic secretion in man under stimulation by cerulein and secretin].

We have investigated in stimulated human pancreatic juice the presence of the following peptides: insulin, glucagon, gastrin, somatostatin, VIP and secretin. Collection of pancreatic juice (3 periods: 20 min each) was completed by endoscopic cannulation of the pancreatic duct during the infusion of secretin (0.5 U/kg/h) and cerulein (75 ng/kg/h) in 6 healthy volunteers. Pure pancreatic juice was recovered in the presence of kallikrein inhibitor (iniprol 8,000 U/ml) in refrigerated collection tubes (4 degrees C). The material was acidified, boiled for 5 min and centrifuged. Radioimmunoassays were performed on the supernatant solutions. The elution profiles on Sephadex G 25 gel filtration of the immunoreactivities were compared with standard samples of hormones, immuno-reactive insulin, glucagon and somatostatin were found in every sample: insulin was present at a constant level (50 microU/ml) during the three periods of collection; glucagon was encountered in large amounts in the first sample and decreased significantly during the subsequent periods; somatostatin which occurred at a low level during the first period was significantly increased in the following periods. Gastrin, VIP and secretin were undetectable or only inconstantly found in very small amounts. These results are in agreement with a two-directional secretion of the human pancreatic endocrine cells. The cellular origin and function of these exocrine secreted peptides need further studies.

Adult↗
PubMed1985

[Yag laser photocoagulation and monopolar electrohydrocoagulation: randomized study of the hemostatic effect on experimental hemorrhagic ulcer in dogs].

The purpose of this randomized study was to compare the effects of two methods of hemostasis--photocoagulation using YAG Neodyme laser and liquid monopolar electrocoagulation--on acute experimental bleeding ulcers created in the dog stomach with an ulcer-maker. One hundred and fifty-three lesions were made and randomized into 3 groups; 51 lesions were treated with photocoagulation and complete hemostasis was achieved in all cases. Hemostasis was obtained in 80 p. 100 of 51 ulcers treated with liquid electrocoagulation. Control untreated ulcers remained hemorrhagic after 45 min of observation. The mean external muscle injury on day 7 was 55 p. 100 after photocoagulation and 65 p. 100 after liquid electrocoagulation. On day 14, mean external injury was 60 p. 100 after photocoagulation and 75 p. 100 after liquid electrocoagulation (non-significant difference). On day 7, the mean re-epithelization index, expressed as the percentage of the original ulcer diameter, ranged from 8 to 10 p. 100 in each trial group. On day 14, reepithelization covered 78 p. 100 of control ulcers and 72 p. 100 of photocoagulated ulcers (NS). This percentage falls to 47 p. 100 in ulcers treated with liquid electrocoagulation (p less than 0.01 when compared with ulcers treated with photocoagulation). Photocoagulation seemed to be more efficient in ensuring hemostasis and external muscle injury was correlated with the energy delivered. External muscle injury could not be controlled by liquid electrocoagulation. However the difference in the percentages of mean external muscle injury between the two methods was not significant. Therefore, in man, the risk of perforation is certainly slight and not very different whatever the method of hemostasis considered.

Animals↗
PubMed1984

Dopamine receptors in a human colonic cancer cell line (HT29). Some receptor-related biological effects of dopamine.

The presence of dopamine receptors in normal colonic cells has been postulated from physiological studies. The existence of such receptors in human colonic tumor cells and their role in tumor progression are still unknown. The aim of the present work was to characterize the dopaminergic receptors in a human colonic adenocarcinoma cell line (HT29) and to evaluate the effect of dopamine on cAMP, protein and DNA synthesis. The binding characteristics of 3H-dopamine on the tumor cells were rapid, reversible, specific, saturable and stereospecific. The first site characterized corresponds to a D3 subtype:KD 3.09 nM, insensitive to sulpiride, unrelated to adenylate cyclase. Competitive inhibitions of 3H-dopamine binding by different drugs showed the existence of a second binding site, D1, with an apparent affinity for dopamine of 6,700 nM. The rank order of potency of inhibitors of 3H-dopamine binding was: haloperidol greater than dopamine greater than cis flupenthixol greater than (+) butaclamol greater than (-) butaclamol greater than trans flupenthixol greater than isoproterenol greater than clonidine greater than prazosin. D3 binding sites are modulated with age, Bmax was 116 fmol/10(6) cells on the 5th day and decreased to 8.2 fmol/10(6) cells on the 15th day of culture. Cell culture in serum-deprived medium allowed an increase in the number of high-affinity receptor sites. D1 sites are coupled to adenylate cyclase as shown by a dose-dependent cAMP accumulation from 10(-8) M to 10(-5) M dopamine concentrations. Interacting with D1 sites, dopamine evokes an increase in protein synthesis with no modification of 3H thymidine incorporation. The present results indicate that the human colonic cancer cell line HT29 exhibits dopamine receptors and that stimulation may induce metabolic modifications in the tumor cells.

Binding, Competitive↗
PubMed1984

Purification of radioiodinated somatostatin-related peptides by reversed-phase high-performance liquid chromatography.

In order to set up specific radioimmunoassays for the two N- and C-terminal tetradecapeptides of somatostatin-28 the peptides somatostatin SS14 and SS28 and the somatostatin by-products 1-Tyr-SS14, 11-Tyr-14 and desaminotyrosyl-beta-alanine fragment (1----14) of SS28 were radioiodinated by the chloramine-T or Bolton-Hunter techniques. Reversed-phase high-performance liquid chromatography was shown to be a very efficient and reliable method for the purification of different radioactive reaction media. The corresponding labelled peptides were tested for their relative immunological (radioimmunoassay) and biological (binding studies) properties.

Animals↗
PubMed1984

Immunohistochemical localization of intestinal phospholipase A2 in rat paneth cells.

Using the peroxidase-anti-peroxidase (PAP) technique with a specific rabbit anti-swine intestinal-phospholipase-A2 serum, the immunoreactivity of this phospholipase A2 was localized in rat-intestinal Paneth cells. The specific rabbit anti-swine intestinal-phospholipase-A2 serum did not stain the rat-pancreatic acinar cells which were stained by a specific rabbit anti-swine pancreatic-phospholipase-A2 serum. Specific rabbit anti-swine pancreatic-phospholipase-A2 serum did not stain rat-intestinal Paneth cells. Therefore, there is no cross-immunoreactivity between pancreatic and intestinal phospholipases.

Animals↗
PubMed1984

125I-(Thr34, Nle37)- CCK31-39 a non oxidizable tracer for the characterization of CCK receptor on pancreatic acini and radio-immunoassay of C-terminal CCK peptides.

A derivative of the C-terminal nonapeptide of CCK, namely (Thr34, Nle37) - CCK31-39 was radio-iodinated by conjugation with 125I-Bolton-Hunter reagent. The labelled peptide was purified by RP-HPLC on a C-18 column. Validation of the iodinated peptide was performed by measuring its biological integrity and by studying its binding characteristics on pancreatic acini. 125I-(Thr, Nle)-CCK-9 present the same ability to stimulates amylase release than (Thr, Nle)- CCK-9 and CCK-8. Binding of the radio-ligand to CCK receptors is specific, reversible, saturable. Inhibition of the binding by CCK-related peptides correlates well their biological potencies. 125I-(Thr, Nle)-CCK-9 is able to interact with high affinity CCK receptors. Furthermore, 125I-(Thr, Nle)-CCK-9 is recognized by C-terminal CCK directed antibodies. This reliable tracer could be used as a replacement of CCK-8 since it is protected from risks of oxidation.

Amylases↗
PubMed1984

Chronic vomiting in a case of citrullinaemia detected after treatment by total parenteral nutrition.

We report a case of a 56 year old woman who presented with a long history of chronic attacks of vomiting. On admission to hospital she was cachectic, and attempted parenteral nutrition induced coma. The illness was found to be due to citrullinaemia, a metabolic disorder of the urea cycle. Our patient is the oldest with this disorder so far described in the literature. The main points of the case and its investigation are outlined: hyperammonaemia, amino acid chromatogram, measurement of enzyme activity in skin and liver biopsy material. The therapeutic measures which led to cure are of particular interest.

Amino Acid Metabolism, Inborn Errors↗