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Biomedical subjects

A Ribet

Publications and source records attributed to A Ribet.

At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

Somatostatin analogs: correlation of receptor affinity with inhibition of cyclic AMP formation in pancreatic acinar cells.

Somatostatin inhibited secretin-stimulated cyclic AMP formation in pancreatic acinar cells. The inhibition was only partial. Maximal inhibition reached about 50%. Somatostatin analogs tested inhibited secretin-stimulated cyclic AMP formation with a lower potency than somatostatin. Cys-Aza Ala-Phe-Phe-DTrp-Lys-Thr-Phe-Phe-Cys was found to be an antagonist of somatostatin in inhibiting secretin-stimulated cyclic AMP. Analogs inhibited the binding of 125I-[Tyr11] somatostatin to pancreatic acini. There was a good correlation (r = 0.97) between concentration for inhibiting 50% secretin-stimulated cyclic AMP and receptor binding affinities.

Amino Acid Sequence↗
PubMedDate not supplied

Calcium-dependence of somatostatin binding to receptors.

Binding of 125I-[Tyr11] somatostatin (S14) and 125I-[Tyr1]S14 has been studied in pancreatic acini and cerebral cortex. Ca2+-dependence of somatostatin binding to receptors was observed only with the highly non degradable iodinated analog 125I-[Tyr11] somatostatin but not with 125I-[Tyr1] somatostatin. The inhibitory activity of S14 on secretin-stimulated cAMP cellular content was decreased when Ca2+ concentration in the medium was reduced to 30 nM, indicating that the Ca2+ dependence of somatostatin binding to receptors is also present with the native peptide.

Animals↗
PubMedDate not supplied

Characterization of pancreatic somatostatin binding sites with a 125I-somatostatin 28 analog.

Somatostatin binding to guinea pig pancreatic acinar cell plasma membranes was characterized with an iodinated stable analog of somatostatin 28 (S28): 125I-[Leu8,DTrp22,Tyr25]S28. The binding was highly dependent on calcium ions. In 0.2 mM free Ca2+ medium, binding at 37 degrees C was saturable, slowly reversible and exhibited a single class of high affinity binding sites (KD = 0.05 +/- 0.01 nM, Bmax = 157 +/- 33 fmol/mg protein). Dissociation of bound radioactivity occurred with biphasic kinetics. Rate of dissociation increased when dissociation was measured at a time before equilibrium binding was reached. In 30 nM free Ca2+ medium, binding affinity and maximal binding capacity were decreased by about 4-fold. Decreasing calcium concentrations increased the amount of rapidly dissociating form of the receptor. Somatostatin 14 antagonist, Des AA1,2[AzaAla4-5,DTrp8, Phe12-13]-somatostatin was active at the membrane level in inhibiting the binding. We conclude that using 125I-[Leu8,DTrp22,Tyr25]S28 as radioligand allows us to characterize a population of specific somatostatin receptors which are not different from those we previously described with the radioligand 125I-[Tyr11]-somatostatin. Somatostatin receptors could exist in two interconvertible forms. Calcium ions are an essential component in the regulation of the conformational change of somatostatin receptors.

Animals↗
PubMedDate not supplied

The quantitative distribution of certain enzymes along the small intestine of the rat and its correlation with the villous area and the Paneth cells.

The distribution of lysozyme, alkaline phosphatase, aminopeptidase, maltase and amylase was studied throughout the small intestine of the adult rat. Lysozyme activity increases along the length of the small intestine and the behaviour of this enzyme slightly differs from the mucosal enzymes reported in this investigation. A positive correlation is found between the percentage of crypts with granulated Paneth cells and the lysozyme activity. This corroborates with the secretory origin of this enzyme from these intestinal cells.

Alkaline Phosphatase↗
PubMedDate not supplied

[Functional pancreatic studies in the diagnosis and treatment of chronic pancreatitis].

The diagnosis of chronic pancreatitis is usually established by clinical history and morphological criteria based on radiological and/or endoscopic (ERCP) findings. When these morphological signs are absent or equivocal, pancreatic function testing is necessary. Direct testing by duodenal intubation with hormonal stimulation is still considered as the reference method ("gold standard"). Numerous indirect tests have been introduced to replace the duodenal intubation which is rarely well accepted and difficult to repeat. Moreover this technique is only available in highly specialized centres. Among the tubeless tests, the Paba test and the pancreolauryl test are gaining interest. Several modifications of these tests have improved their sensitivity and specificity. In most instances, these tests are unable to detect mild pancreatic insufficiency. However their reproducibility in individual cases could be useful for the follow-up of patients with proven pancreatic insufficiency, particularly with regard to the efficacy and the compliance of replacement therapy.

Chronic Disease↗
PubMedDate not supplied

[Incidence of colorectal cancer in the Haute-Garonne Department. Evaluation of 2 years of registration (1982-1983)].

During a two-year period ending in 1983, 882 colorectal cancers (CRC) were diagnosed among 820,000 residents in the department of Haute-Garonne (France). The age-standardized incidences were 24.3 and 19.1 per 100,000 in men and 15.2 and 9.5 per 100,000 in women, for colon and rectal carcinomas respectively. The Haute-Garonne population-based registry showed one of the highest rates of risk of CRC in Europe. A relatively high incidence of rectal cancer, a marked male preponderance particularly in left-side colon cancers, and a higher mean age in female patients (67.1 +/- 11.6 and 70.2 +/- 11.9 (p less than 0.001] was observed. Distribution of CRC within the department was heterogeneous. Although there was no significant difference between urban and rural areas, some regions showed a higher incidence (the "Volvestre" in both sexes and the "Riviere" in women) whereas the "Pyrénées Centrales" showed a lower incidence in women only. CRC was often diagnosed at an advanced stage (Dukes A: 26.1 p. 100, Dukes B: 22.2 p. 100, Dukes C: 27.4 p. 100, visceral metastases: 24.4 p. 100 especially in women (p less than 0.02). Among symptom-free patients (4.5 p. 100) cancers limited to the colonic wall represented 71.4 p. 100 of cases. This suggests that prognosis of CRC could be improved by routine screening of healthy populations. Surgery was performed in 91 p. 100 of colonic cancers and 85 p. 100 of rectal cancers but was considered to be curative in only 55 p. 100 of all cases.

Adult↗