Search PubMed⌕ Search

Biomedical subjects

K Tabata

Publications and source records attributed to K Tabata.

At least 109 records · Page 6Linked to original sources
PubMed1984

Gastric secretory conditions and plasma gastrin levels in rats after prolonged treatment with cimetidine.

Effects of 4 weeks of treatment with oral cimetidine, 100 mg/kg twice daily, on gastric secretion and plasma gastrin levels were studied in rats. Pylorus ligation-induced and pentagastrin-stimulated gastric secretions were little changed at days 1, 3, and 10 after cessation of cimetidine treatment as compared to the controls. Histamine-stimulated acid secretion was significantly higher in the cimetidine-treated group than in the controls at day 3 after cimetidine treatment but was unchanged at days 1 and 10. A single oral administration of cimetidine at 100 mg/kg significantly increased plasma gastrin levels 4 hr after the treatment in refed rats but not at 2 and 8 hr later. Plasma gastrin levels significantly decreased at days 3 and 10 after cessation of cimetidine treatment as compared to the controls. Thus, while prolonged treatment with cimetidine induces a transient increase in response of parietal cells to histamine and a reduction of food-stimulated gastrin release, it does not seem to induce other appreciable changes in gastric secretion.

Animals↗
PubMed1984

Role of lymphoid nodules in pathogenesis of indomethacin-induced gastric lesions in dogs.

Pathogenesis of indomethacin-induced gastric lesions in beagles was studied morphologically. While a single oral administration of indomethacin (20 mg/kg) did not induce visible lesions in the stomach of male beagles, repeated administration once daily for 5 or 10 days induced gastric erosions or ulcers, mainly in the antrum. When this compound was given once or repeatedly, histological examination showed that the total number of lymphoid nodules both in the fundus and antrum tended to increase or significantly increased. The number of large nodules (over 350 micron in diameter) was significantly increased, particularly in the antrum. Some of these enlarged nodules seen at the surface of the mucosa showed damage at the luminal area, and the lesions were microscopically visible. Indomethacin is known to disrupt the gastric mucosal barrier in dogs, leading to increased back-diffusion of acid. Our findings and those of others suggest that indomethacin may induce lesions in specific portions of the dog stomach, initiated by enlargement of lymphoid nodules followed by damage to some of these nodules, probably due to a corrosive effect of gastric juice through the disrupted mucosal barrier.

Administration, Oral↗
PubMed1984

Sensitive radioimmunoassay for measurement of circulating peptide YY.

A radioimmunoassay with sufficient sensitivity to detect the recently discovered, circulating peptide YY in the majority of healthy adults has been developed. The antiserum to synthetic peptide YY raised in rabbits essentially showed no cross-reactivity with bovine or porcine synthetic pancreatic polypeptide, neurotensin, or neuropeptide Y, but cross-reacted to the extent of 0.03% with synthetic peptide HI. The minimum detectable limit of the assay for plasma peptide YY was 20 pg/ml with coefficients of variation less than 16%. The immunoreactivity of peptide YY isolated from healthy adult plasma had a gel-filtration chromatographic profile similar to that of synthetic peptide YY. Fasting levels of peptide YY in plasma from 127 of 137 (92.7%) ostensibly healthy adults were measurable and showed a log-normal distribution. Using the maximum-likelihood estimation method, we calculated the normal range to be 13-178 pg/ml with a geometric mean value of 49 pg/ml. The fasting plasma peptide YY levels showed no significant age or sex dependency.

Adult↗
PubMed1984

Decrease in alkaline secretion during duodenal ulceration induced by mepirizole in rats.

The mechanisms by which the potent antiinflammatory agent, mepirizole, causes duodenal ulceration were investigated in the rat. After subcutaneous administration of 200 mg/kg of mepirizole, basal gastric acid secretion remained unchanged for 5 h but duodenal alkaline output, reliably measured, decreased significantly (p less than 0.05) within 2 h. The decrease was maximal (-45%) at 3 h and persisted for a total of 6 h. The duodenal alkaline secretion returned to near normal by 24 h. A dose-response study showed that the threshold ulcerogenic dose of mepirizole (30 mg/kg) did not significantly reduce alkaline secretion, whereas higher doses did. Plasma levels of immunoreactivity of gastrin, pancreatic polypeptide, vasoactive intestinal polypeptide, and secretin were not changed at either 6 or 24 h after oral mepirizole. Vasoactive intestinal peptide levels in the duodenal mucosa were increased by 158% at 24 h after administration. Secretin levels in the duodenal mucosa were decreased by greater than 60% at both 6 and 24 h after drug treatment. Intravenous secretin (1 CU/kg X h) had no effect on duodenal alkaline secretion in either saline- (154 mM NaCl) or mepirizole-treated animals. Exogenous 16,16-dimethyl prostaglandin E2 (10 micrograms/kg X h, i.v.) reversed the action of mepirizole on duodenal alkaline secretion. These findings suggest that mepirizole causes a reduction in duodenal alkaline secretion that can be reversed by administration of an exogenous prostaglandin.

16,16-Dimethylprostaglandin E2↗
PubMed1983

Correlation between the antitumor activity of a polysaccharide schizophyllan and its triple-helical conformation in dilute aqueous solution.

Eight samples of a polysaccharide schizophyllan ranging in weight-average molecular weight Mw (in water) from 5 x 10(3) to 1.3 x 10(5) were prepared and their antitumor activity (expressed in terms of the tumor inhibition ratio) against Sarcoma 180 ascites, intrinsic viscosities [eta], and gel-filtration chromatograms in aqueous solution were determined. The tumor inhibition ratio was essentially unity for samples with Mw higher than 9 x 10(4), but reduced to zero or even to a negative value when Mw was lower than 10(4). The [eta] data combined with the chromatographic data showed that above Mw approximately 9 x 10(4) the predominant species of schizophyllan in aqueous solution is the previously found rigid triple helix, whereas below Mw approximately 9 x 10(4) both triple helices and single chains coexist in the solution and the fraction of triple helices decreases monotonically to zero as Mw is decreased to 5 x 10(3). From these findings it was concluded that the antitumor potency of schizophyllan in water is related to the amount of triple helices relative to that of single chains.

Journal Article↗
PubMed1983

Effects of 16,16-dimethyl-PGE2-methyl ester on aspirin- and indomethacin-induced gastric and intestinal lesions in mini pigs.

Aspirin, 100 mg/kg, given only twice at intervals of 16 h to fasted mini pigs induced lesions in the body but had no effect on the antrum and small intestine. Indomethacin, 40 mg/kg, given once daily for 10 consecutive days to non-fasted mini pigs very weakly irritated the pig stomach but induced multiple superficial lesions in the jejunum and ileum. 16,16-Dimethyl-PGE2-methyl ester, 10 micrograms/kg in two divided doses or 20 micrograms/kg in four divided doses for 10 days, markedly inhibited the aspirin- or indomethacin-induced gastric and intestinal lesions in mini pigs, respectively.

16,16-Dimethylprostaglandin E2↗
PubMed1982

Effects of prolonged treatment of pirenzepine 2HCl on gastric secretion and plasma gastrin levels in rats.

Gastric secretory functions and plasma gastrin levels in rats after the prolonged treatment of pirenzepine 2HCl were evaluated. Pirenzepine 2HCl at 100 mg/kg was given p.o. twice daily for 4 weeks. Control animals were given saline alone. The test agent potently inhibited gastric secretion in pylorus-ligated rats and fistula rats stimulated with pentagastrin and histamine before and after cessation of 4 weeks' treatment. At 1 day after the treatment, the acid output slightly decreased in pylorus-ligated rats and significantly decreased in fistula rats stimulated with secretagogues. At 3 days, the acid output was slightly increased in pylorus-ligated rats and significantly increased in fistula rats stimulated with pentagastrin but was unchanged in the case of histamine stimulation. At 10 days, the gastric secretion in pylorus-ligated rats tended to increase but the acid output in fistula rats was not affected. Pirenzepine 2HCl increased the plasma gastrin levels in normal rats and at 1 day after the treatment, but had no effects at 3 and 10 days. Propantheline Br showed much the same results as seen with pirenzepine 2HCl. Cessation of prolonged treatment with pirenzepine 2HCl appears to increase only slightly and transiently the sensitivity of gastric secretory cells.

Animals↗
PubMed1981

Ultrasonic degradation of schizophyllan, an antitumor polysaccharide produced by Schizophyllum commune Fries.

Schizophyllan, a water-soluble beta-D-glucan elaborated by Schizophyllum commune Fries, was partially depolymerized by ultrasonic irradiation to a low-molecular-weight polysaccharide, designated "sonic-degraded schizophyllan". Both native and degraded polysaccharides exhibited essentially the same antitumor activities against Sarcoma-180 ascites. Both glucans are comprised solely of D-glucose residues and have a main chain of (1 leads to 3)-beta-D-glucopyranosyl residues, one out of three glucose residues being attached as single, (1 leads to 6)-beta-D-glucopyranosyl groups. Although both glucans have similar structural features, significant differences are observed in such physical properties as molecular weight and intrinsic viscosity. End-group analysis by using radioisotope-labeled glucans suggests that ultrasonic degradation occurs mainly by cleavage of glycosidic bonds of the main chain of schizophyllan. The molecular weights of the native and sonic-degraded schizophyllan were shown to be 75% of those of corresponding, original schizophyllan preparations, suggesting that there is no anomalous linkage sensitive to periodate oxidation, and ultrasonic irradiation may cause random hydrolysis of (1 leads to 3)-beta-D-glucosidic linkages in the main chain.

Animals↗
PubMed1981

Does indomethacin activate healed gastric ulcers in the dog?

Effects of indomethacin on healed partially healed gastric ulcers in the dog were studied. Gastric ulcers were produced by submucosal injection of 1 ml of 40% acetic acid solution into the bordering area of the fundus and antrum of the stomach. Indomethacin, 20 mg/kg, was given orally once daily for 5 days beginning on the 50th day after ulceration. While erosions or deep ulcers were produced by indomethacin, healed or partially healed acetic acid ulcers were not aggravated. Mechanisms involved in this strong resistance of healed ulcers to the ulcerogenic agent remain to be determined.

Animals↗
PubMed1981

[Effects of ranitidine, a new histamine H2-receptor antagonist, on histamine- and aspirin-induced gastric ulcers in rats and dogs (author's transl)].

Male donryu rats (200-220 g) and mongrel dogs of both sexes (7-20 kg) were used. Histamine-induced ulcers: Histamine 2HCl (100 mg/kg) was given i.p. to 24 hr-fasted rats and the animals were killed 4 hr later. Histamine 2HCl in beeswax (20 mg/kg) was given i.m. to dogs once daily for 5 days and the animals were killed on the 6th day. Aspirin-induced ulcers: Aspirin (100 mg/kg) was given p.o. to the 24 hr-fasted rats and dogs twice (15 h apart) and the animals were killed 9 hr after the second administration of aspirin. Either the length (mm) or ares (mm2) of each ulcer was measured, summed, and used as an ulcer index. Cimetidine and gefarnate were used as reference drugs. Ranitidine dose-dependently inhibited both histamine- and aspirin-induced ulcers in rats and dogs. On the basis of ED50, the antiulcer effect of ranitidine on histamine-induced ulcers was about two times (in rats) or 9 times (in dogs) more potent than cimetidine. However, the antiulcer effect of ranitidine on aspirin-induced ulcers was 1.7 times more potent than cimetidine (in rats) or almost equal (in dogs) to cimetidine. Gefarnate had an insignificant effect on both histamine- and aspirin-induced ulcers.

Animals↗