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Biomedical subjects

A Ribet

Publications and source records attributed to A Ribet.

At least 73 records · Page 4Linked to original sources
PubMed1984

Early and late complications after endoscopic sphincterotomy for biliary lithiasis with and without the gall bladder 'in situ'.

Endoscopic sphincterotomy has gained wide acceptance in the treatment of biliary lithiasis. We attempted endoscopic sphincterotomy in 443 patients and were successful in 407 (92%). Sphincterotomy was carried out with the gall bladder in situ in 234 cases (57%) of advanced age or high surgical risk. Immediate complications occurred in 7%, of which haemorrhage was the most frequent. The mortality rate was 1.5%. Three hundred and sixteen endoscopic sphincterotomies were performed more than six months before writing and follow up was available for 226 (72%) from six to 78 months. Late complications were observed in 16 patients with gall bladder 'in situ' (12%); the most frequent was cholecystitis in 6%. In five patients of the group without gall bladder, four had cholangitis related to retained or recurrent stones, and one restenosed . No episodes of cholangitis were observed in patients without stones despite reflux of barium up the biliary tree as observed during a barium meal examination.

Aged↗
PubMed1984

Binding of somatostatin to pancreatic acinar cells.

The binding of 125I-[Tyr11]somatostatin to guinea pig pancreatic acini was saturable and temperature, protein, and radioligand concentration dependent. Dissociation rate was very slow (t1/2 = 193 +/- 24 min). Scatchard analysis revealed a single class of binding sites with a Kd of 0.28 +/- 0.02 nM and a maximal binding capacity of 72 +/- 10.6 fmol/mg prot. There was a strong correlation between binding capacity and extracellular calcium concentration. Incubating acini in EGTA-containing medium with no added Ca2+ caused a 50% decrease in maximal binding capacity with a decrease in receptor affinity. Furthermore, in the absence of calcium, bound somatostatin was rapidly released (t1/2 = 14 +/- 1 min). Subcellular fractionation studies and acid treatment of acini incubated with the tracer showed that most of the somatostatin binding sites were located on the cell surface. Agents that altered cellular calcium in pancreatic acini, such as analogues of cholecystokinin and cholinergic agents, also inhibited the binding of 125I-[Tyr11]somatostatin by a calcium-dependent process. We conclude that somatostatin binds to specific plasma membrane receptors to form a slowly reversible complex that is highly reactive with calcium. Cell calcium-mobilizing agents decrease the affinity of acinar somatostatin receptors for somatostatin.

Animals↗
PubMed1984

[Cytologic demonstration of immunoreactivity characteristic of adenopituitary peptides in the digestive epithelium of the rat and man].

Using immunoperoxidase techniques, the possible localization of pituitary regulatory peptides in fundic, antral and duodenal mucosae was investigated in both rat and man. All results obtained were similar in the two species. No glycopeptide (FSH, LH, TSH) was detected in the digestive tract. With different antisera directed against beta-lipotropin, alpha-MSH, beta-MSH, endorphins, ACTH 1-24, ACTH 17-39, a positive reaction was only obtained in the antral mucosae with an antiserum specific for the synthetic fragment 17-39 of ACTH. However neither the common precursor, proopiomelanocortin, nor the complete sequence of ACTH seem to be present in endocrine cells of the digestive tract. On the other hand, three antisera, directed against human growth hormone (GH), visualized numerous endocrine cells scattered in the glandular epithelium of the fundic and antral mucosae. Most cells were identified as ECL type in the gastric mucosae. Others are probably of the gastrin cell type in the antral mucosa, since these cells could be visualized on adjacent sections either with the antiserum against GH, or with a specific antiserum for gastrin.

Adrenocorticotropic Hormone↗
PubMed1984

[Inhibition of the adherence of leukocytes labelled with Cr-51 in colorectal cancer].

The leukocyte adherence inhibition test (LAI) is an in vitro test of immunity. Its high sensitivity in early cancer and its organ-specificity are of great interest in the study of human tumors. We developed an isotopic method (51Cr-LAI) for colorectal cancer, which has the advantage of being easier to perform than optic-counting assays. 87 patients (35 colorectal cancers, 29 benign diseases, 23 cancers of non-colorectal origin) were studied. We obtained a statistically significant difference between the mean LAI index for colorectal cancers and that for controls (p less than 0.01). LAI values greater than 13 p. 100 were considered positive. The specificity of the test was 94 p. 100 and the sensitivity for all colorectal cancers was 66 p. 100 with the highest value in the Dukes A group (LAI = 83 p. 100). Tests were negative in disseminated neoplasms. The actual fields of interest of LAI in tumor immunology and clinical research are discussed.

Chromium Radioisotopes↗
PubMed1984

[24-hour duodenal pH-recording in chronic pancreatitis].

Decreased pancreatic bicarbonate secretion may be responsible for the low duodenal pH in chronic pancreatitis as compared to the normal. We have therefore performed a 24-hour continuous duodenal pH recording in 7 patients with chronic pancreatitis and in 7 controls. The comparison of results, expressed as the percent of the time with pH under 3, 4, 5 or 6, shows that in chronic pancreatitis, the duodenal pH was significantly lower than in normal subjects, particularly during the postprandial periods. The lower pH found in pancreatitis, causing an impairement of the catalytic activity of endogenous or exogenous pancreatic enzymes could both contribute to malabsorption and decrease the efficacy of substitutive pancreatic extracts.

Adult↗
PubMed1983

Binding of somatostatin to guinea-pig pancreatic membranes: regulation by ions.

Somatostatin receptors were characterized on guinea-pig pancreatic acini membranes using 125I-[Tyr11] somatostatin 14 as a radioligand. In 0.1 mM Ca2+ buffer the binding was saturable and slowly reversible, exhibiting a single class of high affinity binding sites (KD = 0.15 +/- 0.03 nM) with a maximal binding capacity (B max) of 178 +/- 18 fmol/mg protein. In 30 nM) free Ca2+ buffer, the binding was highly reversible. Affinity and B max were decreased by about 2-fold. Ca2+ exhibited an EC50 of 2.4 +/- 0.9 microM to potentiate the binding of somatostatin. Na+, but not K+, inhibited the binding: Bmax was decreased with no change in affinity. Somatostatin analogs inhibited the binding of 125I-[Tyr11] somatostatin 14. The relative potencies were: somatostatin 14 greater than somatostatin 28 = [Nle8]somatostatin 28 greater than [D Tryp8, D Cys14]somatostatin 14.

Animals↗
PubMed1983

Presence of VIP receptors in a human pancreatic adenocarcinoma cell line. Modulation of the cAMP response during cell proliferation.

It is known that the human exocrine pancreas responds to secretin stimulation more than does VIP, a structurally related peptide. We looked for the receptors for those polypeptides in a human pancreatic cancer cell line grown in culture and in nude mice. By analysing the cAMP responses and the 125I-VIP binding we found VIP receptors with a KD of 1.5 10(-9) M. Secretin stimulates the adenylate cyclase through the VIP receptor sites with a KD of 1.7. 10(-6) M. We noted also that during cell proliferation in culture there was about a 5 fold increase of the cAMP response to VIP.

Adenocarcinoma↗
PubMed1983

Bimodal regulation of pancreatic exocrine function in vitro by somatostatin-28.

The action of natural and synthetic somatostatin-(1--28), [Nle8]somatostatin-(1--28), somatostatin-(15--28), and somatostatin-(1--14) was examined in dispersed acini from guinea pig pancreas. At high concentrations, the 28-amino acid form of somatostatin increased amylase release, outflux of 45Ca, cellular cGMP, and to a lesser extent cellular cAMP. The increase in amylase release was suppressed by dibutyryl cGMP but was not modified by theophylline or atropine. Binding of 125I-labeled [Thr28, Nle31] cholecystokinin-(25--33) was inhibited by [Nle8]somatostatin-(1--28). These effects required the entire 28-amino acid peptide and appeared to result from occupation of cholecystokinin receptors. It is postulated that they involve interactions between the C-terminal and the N-terminal sequences of the molecule with the participation of the amino acid in position 8. At low concentrations, natural and synthetic forms of somatostatin-(1--28) and somatostatin-(15--28) inhibited secretin- and vasoactive intestinal peptide (VIP)-stimulated increases in cellular cAMP concentration. No difference was found between the potency of somatostatin peptides, indicating that the tetradecapeptide somatostatin-(15--28) is sufficient to exert an inhibitory action on secretin- and VIP-stimulated cellular cAMP concentration. By contrast, the somatostatin fragment S-(1--14) was inactive on pancreatic cellular function.

Amylases↗
PubMed1983

Control of cyclic AMP accumulation in dog acini: its relation to amylase release.

In dispersed acini from dog pancreas, exogenous derivatives of cAMP stimulated the amylase release; 8-Br-cAMP was a more potent stimulant than Bt2-cAMP, and induced a potentiation of the amylase release stimulated by cerulein. Both secretin and vasoactive intestinal peptide (VIP), increased cellular cAMP, with a greater potency for secretin, and supramaximal concentration of secretin plus VIP increased cellular cAMP to the same degree as that obtained with secretin alone. 125I-VIP-binding studies showed that in dog pancreatic acini there is a 95% decrease in the number of VIP-preferring receptors with minor changes in receptor affinity as compared to guinea-pig pancreas. The absence of effect between secretin or VIP and cerulein in stimulating amylase release could likely be explained by the low number in VIP-preferring receptors on dog pancreatic acini.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1983

[Critical study of the analysis of lactoferrin in duodenal fluid in the diagnosis of chronic pancreatitis].

In a prospective study we have measured the lactoferrin level of duodenal juice under secretin plus caerulein pancreatic stimulation in 78 subjects. Subjects was divided in 4 groups as follows: 27 controls, 11 pancreatic disease without chronic pancreatitis (CP), 17 CP and 23 suspicions of CP. Lactoferrin was assayed by radial immunodiffusion and the level was referred to lipase activity. The test was considered as positive when lactoferrin (microgram/ml) X 100/lipase (U/ml) greater than 0.1. No one control subject had a positive test, 2 pancreatic cancers out of 4, 1 acute pancreatitis out of 7, 12 CP out of 17 had a positive test. The sensitivity (0.71) and the specificity (0.92) of the test do not allow us to propose this test as unequivocal in the diagnosis of CP.

Body Fluids↗
PubMed1982

[Currently recommended use of the Hemoccult for the detection of rectocolic tumors].

Because colorectal carcinoma is both very frequent and extremely serious, diagnosis and treatment of this cancer are a major Public Health issue in France. The recognition of the filiation between polyps and cancer has led to considering prevention of colorectal cancer through the detection of polyps. The usefulness of the hemoccult test is discussed. Reported results warrant the rejection of this method for the individual detection of colorectal tumors because of poor sensitivity. Conversely, there are grounds for advocating the use of the hemoccult test for mass screening on certain conditions; the most important of these is that a negative test must not be considered as sufficient to eliminate the diagnosis. If screening plans with the hemoccult test are implemented, they will have to be coordinated with an important health education program to promote individual prevention using endoscopy, particularly in high risk and symptomatic subjects.

Colonic Neoplasms↗
PubMed1982

Dopamine-stimulated cyclic AMP and binding of [3H] dopamine in acini from dog pancreas.

Dispersed acini from dog pancreas were used to examine the ability of dopamine to increase cyclic AMP cellular content and the binding of [3H] dopamine. Cyclic AMP accumulation caused by dopamine was detected at 1.10(-8) M and was half-maximal at 7.9 +/- 3.4 10(-7) M. The increase at 1.10(-5) M, (7.5-fold) was equal to the half-maximal increase caused by secretin at 1.10(-9) M. Haloperidol, a dopaminergic receptor antagonist inhibited cyclic AMP accumulation caused by dopamine. The IC50 value for haloperidol, calculated from the inhibition of cyclic AMP increase caused by 1.10(-5) M dopamine was 2.3 +/- 0.9.10(-6) M. Haloperidol did not alter basal or secretin-stimulated cyclic AMP content. [3H] Dopamine binding was studied on the same batch of cells as cyclic AMP accumulation. At 37 degrees C, it was rapid, reversible, saturable and stereospecific. The Kd value for high affinity binding sites was 0.43 +/- 0.1.10(-7) M and 4.7 +/- 1.6.10(-7) M for low affinity binding sites. The concentration of drugs necessary to inhibit specific binding of dopamine by 50% was 1.2 +/- 0.4.10(-7) M epinine, 4.1 +/- 1.8.10(-6) M fluphenazine, 8.0 +/- 1.6.10(-6) M haloperidol, 4.2 +/- 1.2.10(-6) M cis-flupenthixol, 2.7 +/- 4.0.10(-5) M trans-flupenthixol, less than 1.10(-5) M apomorphine, sulpiride, naloxone and isoproterenol.

Amylases↗
PubMed1982

Histological variations of the duodenal mucosa in chronic human pancreatitis.

From 16 volunteers with chronic pancreatitis and 36 healthy subjects duodenal biopsies were taken 15--20 cm beyond the papilla of Vater. Several morphometric parameters were calculated. The main results show: a significant decrease of villous area and height but not of the number of intestinal villi; a significant increase of Paneth cells; and a slight decrease in the number of glandular mitoses. This study suggests in man, a possible relationship between exocrine pancreatic secretion and the intestinal mucosa and a trophic action of pancreatic juice on the proliferation and the differentiation of the intestinal mucosa.

Biopsy↗
PubMed1982

Synthesis of [8-norleucine]somatostatin-28.

Because of the high tendency of natural and synthetic somatostatin-28 to S-oxide formation at methionine-8 via air-oxidation, the 8-norleucine analogue was prepared following the synthetic route previously elaborated for the parent methionine peptide. [Nle8]-somatostatin-28 was obtained at a high degree of purity as judged by different analytical assays. It was found to possess the identical stimulatory effect on amylase release from pancreatic acini as the natural peptide extracted from porcine intestine.

Amino Acids↗