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Biomedical subjects

S Nishihara

Publications and source records attributed to S Nishihara.

At least 91 records · Page 5Linked to original sources
PubMed1987

Pharmacokinetics of pirenzepine in patients with gastric or duodenal ulcers.

1. The pharmacokinetics of pirenzepine (Gastrozepin) was studied after single and multiple oral administration in gastric ulcer and duodenal ulcer patients. 2. With a dose of 50 mg of pirenzepine, plasma levels reached a maximum 2 h after the administration in both groups (gastric ulcer patients: 57.2 +/- 31.8 ng/ml, duodenal ulcer patients: 48.0 +/- 18.0 ng/ml), and decreased bi-phasically with an elimination half-life (t1/2 beta) of 13.9 +/- 4.0 and 17.9 +/- 4.5 h, respectively. The area under the plasma level curve were 844 +/- 319 ng X h/ml and 663 +/- 151 ng X h/ml in the respective group. 3. The plasma levels of pirenzepine after multiple administration (50 mg was given as a loading dose, and thereafter 25 mg was given as a maintenance dose at an interval of 12 h for 7 days) maintained certain steady state levels from just after the start of administration. 4. It can be concluded that there is no significant difference in the pharmacokinetics of pirenzepine between gastric and duodenal ulcer patients. It can be judged that twice-daily administration of pirenzepine is enough for ulcer treatment.

Administration, Oral↗
PubMed1986

Inhibitory effect of etintidine (BL-5641), a new type of H2 receptor antagonist, on binding of [3H]-cimetidine to plasma membrane and histamine-stimulated cellular cAMP production in isolated guinea pig gastric glands.

A comparative study was carried out between the inhibitory effects of cimetidine and those of etintidine (BL-5641), a new type of H2 receptor antagonist, on the binding of [3H]-cimetidine to plasma membranes as well as on histamine-stimulated cellular cAMP production in isolated guinea pig gastric glands. Both cimetidine and etintidine inhibited the binding of [3H]-cimetidine to plasma membranes, in a dose-dependent manner, with an IC50 of 1.70 X 10(-6) M and 0.51 X 10(-6) M, respectively. The two drugs also inhibited histamine-stimulated cellular cAMP production in a dose-dependent manner, shifting the histamine dose-dependent curve of cellular cAMP production to the right. The PA2 calculated from the result obtained was 6.41 for cimetidine and 6.82 for etintidine. These results indicate that etintidine is an H2 receptor antagonist at the cellular level and that its inhibitory effect is approximately 2.5 times as potent as that of cimetidine.

Animals↗
PubMed1986

Aberrant insulinoma in the duodenum.

A rare case of aberrant insulinoma in the duodenum is described. Hyperinsulinemia with typical hypoglycemic symptoms was induced by prolonged fasting. Selective angiography demonstrated a tumor supplied from the first branch of the jejunal artery, and duodenoscopy revealed a submucosal tumor at the third portion of the duodenum. An increase in venous plasma immunoreactive insulin concentration was evident in the vein draining from the tumor, by sampling through percutaneous transhepatic catheterization. Hypoglycemia was ameliorated after the removal of the submucosal tumor of the duodenum. Histologic and immunocytochemical characterization of the tumor showed an insulinoma, predominantly composed of cells with typical B-cell-like granules. The acid extract of the tumor contained 1.2 U/g of insulin, and this insulin, analyzed by reverse-phase high-pressure liquid chromatography, revealed that it had the same amino acid structure as that of human insulin.

Adenoma, Islet Cell↗
PubMed1986

Mn2+-probe ESR method for the analyses of the dissociation of charged residues on the surface of immunoglobulins.

Dissociation of charged residues on the surface of immunoglobulins was analysed by an Mn2+ probe ESR method that has been developed in our previous work. Several kinds of IgG proteins and their Fab and Fc fragments were used for the experiments. The pH dependence of the intensity of ESR signals was analysed. It was shown that the number of Asp, Glu and His residues on the surface of Fc is about twice as many as that of Fab. The accessible surface area of amino acid residues calculated using X-ray crystallographic data is quite consistent with the present ESR experiments. This indicates that the number of the Asp, Glu and His residues on the surface of IgG molecules in solution is similar to that in the crystal. The Mn2+-probe ESR method was also applied to other classes of immunoglobulins, i.e. IgA and IgM. It was demonstrated that the IgA protein, which is known to lack the ability to bind Clq, has on the surface of it a smaller number of Asp, Glu and His residues as compared to IgG and IgM proteins. On the basis of these results obtained by the Mn2+-probe ESR method, we suggest that the Clq molecule, which is a basic protein, interacts favorably with the Fc portion whose surface is more negatively charged with Asp and Glu residues, compared to the Fab portion. Fine adjustment of fitting of the head of the Clq molecule into the CH2 domain of the Fc portion presumably follows for optimum binding. It was also demonstrated that Ser and Thr residues are much more abundant on the surface of Fab than in the case of Fc. We suggest that the Ser and Thr residues on the surface of Fab play an important role for binding of C4b upon activation of the complement system.

Asparagine↗
PubMed1986

Pharmaceutical evaluation of hollow type suppositories. V. Preparation of valproic acid suppository and rectal absorption of valproic acid in rabbits.

Seven kinds of suppositories were constructed with oleaginous base materials (Witepsol H-15 (H-15) and E-85 (E-85]: a conventional type suppository containing valproic acid (VPA) mixed with E-85 (I), a conventional type suppository containing sodium salt of VPA (sodium valproate) (S-VPA) mixed with H-15 (II), hollow type suppositories containing VPA in the forms of oily liquid (free acid) (III), macrogol 1000 or 6000 mixture (IV or V), powder (S-VPA) (VI) and aqueous solution (S-VPA was dissolved in 0.9% NaCl solution) (VII) in each cavity. The content of VPA in type I was decreased considerably by volatility and type II was found to be hygroscopic. Therefore conventional type suppositories containing VPA or S-VPA were not of practical use, whereas III and VI prevented volatility of VPA and minimized the hygroscopic property of S-VPA. Plasma concentration of VPA was measured in rabbits after rectal administrations of III, IV, VI and VII. By using VI, the highest values of the mean of the peak plasma VPA concentration (Cmax) (49.8 +/- 2.6 micrograms/ml) and the mean of the area under the plasma concentration-time curve (AUC) (90.0 +/- 3.7 h X micrograms/ml) were obtained. The Cmax and the AUC estimated after administration of VII were not significantly different from those of VI. The Cmax and the AUC were lower with III than with IV, VI or VII but the extent of bioavailability (EBA) of III was about 80%.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Effect of somatostatin and its analogs on histamine-stimulated cAMP production in isolated guinea pig gastric glands.

The effect of somatostatin-14 (ss-14), somatostatin-28 (ss-28), and [D-trp8]somatostatin-14 ([ D-trp8]ss-14) on both histamine-stimulated cellular cAMP production and [3H]-cimetidine binding on plasma membranes in isolated guinea pig gastric glands was investigated. These three peptides partially inhibited (approximately 50% maximally) the increase of cAMP production stimulated by histamine. There was no inhibition of [3H]-cimetidine binding on plasma membranes from these isolated gastric glands. These results indicate that somatostatin acts directly on parietal cells and inhibits histamine-stimulated cAMP production with no influence on H2 receptor in histamine stimulated gastric secretion. Inhibitory potency of somatostatin and its analogs against histamine-stimulation may be equal at the cellular level.

1-Methyl-3-isobutylxanthine↗
PubMed1984

Tumoricidal adsorption of Staphylococcus aureus organisms on Ehrlich ascites tumor cells sensitized with rabbit antibody.

A tumoricidal effect was observed when protein A-bearing Staphylococcus aureus organisms were adsorbed on Ehrlich ascites tumor cells previously sensitized with antiserum from a rabbit immunized with Ehrlich ascites tumor cells. Electron micrographs showed that staphylococci were firmly attached to the tumor cells, which might explain how effectively the attached cocci killed the tumor cells. The tumoricidal effect was confirmed not only by an in vitro experiment but also by an in vivo one. The possible applications of the tumoricidal adsorption as an indicator for staphylococcal virulence or for selective anti-tumor action was discussed.

Adsorption↗
PubMed1982

Effect of cimetidine o endocrine functions--prolactin.

Effects of cimetidine on the endocrine function were examined in 16 human subjects, i.e. 6 healthy adult volunteers, and each 5 male and female gastro-duodenal ulcer patients. They were all subjected to the examination on the fluctuation of prolactin (PRL) after one-shot intravenous injection of cimetidine. The peptic ulcer patients were orally given 800 mg/day of cimetidine for further 4 weeks. PRL, gonadotropins and sex hormones were determined in the male patients, and only PRL in the females patients. TRH-load test was carried out in all the ulcer patients before and after the administration of cimetidine. The results are shown below: 1) After one-shot intravenous administration of cimetidine 200 mg, serum-PRL significantly increased, the peak level, however, being within normal value range. The increase in PRL was transient, and recovered to the pretreatment value in 60-180 minutes after the administration. 2) During and after the repeated oral administration of 800 mg/day of cimetidine for the consecutive 28 days, serum PRL level did not significantly change. Neither was noted any influence on gonadotropin (LH, FSH) nor sex hormones (estradiol, testosterone) secretion. 3) PRL secretory functions at 500 microgram TRH loading were similar before and after oral administration of cimetidine, without difference in the reactivity.

Adult↗