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Biomedical subjects

B Simon

Publications and source records attributed to B Simon.

At least 289 records · Page 16Linked to original sources
PubMed1983

[Behavior of acid secretion under the long-term daily administration of omeprazol].

The effect of the substituted benzimidazole omeprazole on acid secretion after repeated administration to healthy volunteers has been studied. During repeated dosage of 30 mg once daily inhibition of basal and pentagastrin-stimulated acid output was increased from 30% after the first dose to about 60% after dose 4. The extent of inhibition did not further increase between day 5 and day 10. In four volunteers acid secretion returned to predose levels within 5 days after drug withdrawal. The 24-hour gastric acidity was reduced by about 72% and 82% after 9-day pretreatment with 30 mg and 60 mg omeprazole respectively. The antisecretory effect of omeprazole was independent of peak plasma concentrations. Omeprazole given once daily therefore possesses a long-lasting effect on gastric acid secretion, i.e. for more than 24 hours. This effect appears to be fully reversible since control levels of acid output are reached within 5 days.

Adult↗
PubMed1983

Forskolin induced chloride secretion across the isolated mucosa of rat colon descendens.

The effects of forskolin, a diterpene reported to stimulate adenylate cyclase, on electrolyte transport across the isolated colonic mucosa of rat colon descendens were investigated. Forskolin, over a concentration range of 10(-7)-10(-5) M, dose-dependently increased short circuit current (Isc) and transmural potential difference (Vms). The nearly 2-fold increase in Isc and Vms caused by forskolin was accompanied by a small increase in transmural conductance (Gt). The effects of forskolin were rapid and completely reversible without any loss in tissue sensitivity. Forskolin (5 X 10(-6) M) inhibited the absorption of Na+ and reversed Cl- absorption to secretion. These effects were due to an inhibition of the mucosal-to-serosal fluxes of Na+ and Cl-. Ion substitution experiments revealed that the effects of forskolin were both Na+ and Cl- dependent and these ions were required in the serosal solution. Furosemide (10(-4) M) as well as scilliroside (10(-4) M) reversed and prevented the increase in Isc caused by forskolin. Adenylate cyclase activity in homogenates of colonic mucosa was increased 3-fold by forskolin. These results with rat colon are compared with those reported for rabbit colon and ileum and the mechanism of cyclic-AMP induced Cl- secretion in these epithelia is discussed.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1983

Colonic cyclic AMP metabolism following chronic ethanol consumption in the rat: effect of hormonal secretagogues.

The colonic cyclic AMP system is known to be involved in intestinal secretion and can be stimulated by a variety of gastrointestinal hormones including prostaglandins. We have investigated the effect of chronic ethanol ingestion on the activity of the key enzymes in cyclic AMP metabolism--adenylate cyclase and cyclic AMP phosphodiesterase--in the colonic mucosa of the rat. Chronic ethanol consumption by feeding a nutritionally adequate liquid diet enhanced basal colonic adenylate cyclase activity significantly by 168% (p less than 0.01), but had no effect on colonic low Km cyclic AMP phosphodiesterase activity. In addition, various hormonal secretagogues were used to stimulate colonic adenylate cyclase. Colonic adenylate cyclase exhibited a significantly greater sensitivity and efficacy to prostaglandins and vasoactive intestinal peptide after chronic ethanol ingestion. Since increased intestinal cyclic AMP production due to an increased activity of intestinal adenylate cyclase is known to promote intestinal secretion of water and electrolytes, the frequently observed diarrhea in alcoholics may be explained at least in part by an enhanced production of colonic cyclic AMP.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1983

Effect of chronic ethanol ingestion on the cyclic AMP system of the upper gastrointestinal tract in the rat.

Chronic ethanol consumption significantly increases gastric adenylate cyclase (AC) activity (p less than 0.05) without influencing low Km 3',5'-cyclic adenosine monophosphate (cAMP) phosphodiesterase (PD) activity in the rat. On the other hand, in the duodenum and upper part of the jejunum, chronic ethanol feeding leads to a significant decrease of adenylate cyclase activity (p less than 0.02) and, again, does not affect low Km cAMP phosphodiesterase activity. In addition, the effect of various hormonal secretagoques on small intestinal adenylate cyclase activity was investigated. Prostaglandin I2 and D2, as well as glucagon, do not stimulate AC at all. However, small intestinal adenylate cyclase exhibits a lower sensitivity to prostaglandin E2 and vasoactive intestinal peptide (VIP), and a lower efficacy to VIP after chronic ethanol consumption when compared to controls. The decrease of both basal and stimulated AC activity following ethanol ingestion in the upper small intestine may be due to membrane alterations and tissue damage caused by ethanol. The ethanol-induced increase in gastric AC may be of relevance with respect to an increased acid secretion observed after alcohol administration.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1983

[Inhibition of basal acid secretion by trimethyldesoxy-prostaglandin E2 in humans].

The effect of graded oral doses of trimethyldesoxy-prostaglandin E2 (Ro 21-6937) on basal acid secretion in healthy volunteers was tested over a time period of 6 h. Basal acid output was reduced by 80% after 1500 micrograms Ro 21-6937. Half-maximal inhibition was achieved by 700 micrograms Ro 21-6937. 250 micrograms of this prostaglandin E2 analog showed no detectable antisecretory activity.

Adult↗
PubMed1983

[Suppression of acid secretion and plasma level of a once-daily dose of omeprazole].

The effect of 5-methoxy-2-[( (4-methoxy-3,5-dimethyl-2-pyridinyl)-methyl]sulphinyl)-1H- benzimidazole (omeprazole) on gastric acid secretion after repeated administration to healthy volunteers has been studied. Omeprazole in a dose of 30 mg given once daily for nine days suppressed acid secretion continuously, the inhibitory effect stabilising after five days. Omeprazole was absorbed and rapidly cleared from plasma; the inhibitory effect was related to the area under the plasma concentration-time curve.

Adult↗
PubMed1983

[Cytoprotection with antacids?].

Prostaglandins in very low concentrations which do not inhibit acid secretion protect the mucosa of the gastrointestinal tract against a great number of noxious agents. The protective action of various antacids is likely to be related to its acid neutralizing capacity. Antacids do not prevent lesions evoked by direct necrotising substances such as concentrated ethanol etc. It remains to be established whether the endogenous prostaglandin system is involved in the antiulcerogenic action of some antacids.

Animals↗