Biomedical subjects
Publications and source records attributed to J Tamura.
The plasma exchange using Carcino embryonic Antigen (CEA) value as an index was performed for 3 colonic cancer patients with liver metastasis. A remarkable regression of hepatomegaly in two cases with rectal cancer was obtained and a significant decrease of CEA was observed in all patients.
Effect of morphine dependence and its withdrawal on the 3H-dihydroalprenolol (3H-DHA) binding for beta -adrenergic receptors, beta 1 and beta 2, was examined by a computerized analysis of biphasic Hofstee plots. The relative density of beta 1 and beta 2 receptors in the rat cerebral cortex was found to be approximately 70% and 30%, respectively. In rats rendered dependent on morphine by a subcutaneous implantation of a morphine pellet, the 3H-DHA binding to beta 1 and beta 2 receptors was not altered. During the stage of withdrawal induced by administration of naloxone, however, the 3H-DHA binding to the cerebral particulate fractions was increased, and this increase was due to the increased binding sites in beta 1 and beta 2 receptors. On the other hand, the apparent affinities of beta and beta 2 for atenolol and salbutamol, selective antagonists for beta 1- and beta 2-adrenergic receptors, respectively, were not altered under these experimental conditions. These results suggest that an abrupt increase in cerebral beta 1-receptor binding sites occurs at morphine withdrawal, and the occurrence of such a super-sensitivity in cerebral beta 1 receptor may be involved in the exhibition and/or maintenance of the abstinence syndrome in morphine-dependent subjects.
Characteristics of taurine (2-aminoethanesulfonic acid) transport were studied in freshly isolated rat hepatocytes prepared by a collagenase perfusion technique. The uptake of taurine at 37 degrees C was linear up to 30 min of incubation, but gradually decreased thereafter and reached a plateau at 90 min after initiation of the incubation. Taurine uptake at 4 degrees C by isolated hepatocytes was not saturable, whereas that at 37 degrees C was saturable with the following parameters: Km, 37 microM; Vmax, 0.043 nmoles/mg prot./min; and EA, 5.6 Kcal/mol. The taurine uptake at 37 degrees C was found to be sodium dependent, and this was inhibited competitively by guanidinoethyl sulfonate and beta-alanine with the Ki values of 1.75 mM and 285 microM, respectively. Conjugated cholate, conjugated chenodeoxycholate, alanine, isethionate and leucine had no effect on the taurine uptake. The present results indicate that taurine uptake by isolated hepatocytes consists of unsaturable and energy independent, and carrier-mediated and energy dependent transport processes.
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Chronic toxicity of clobetasone-17-butyrate, an anti-inflammatory corticosteroid, was investigated in rats. Subcutaneous administration with the drug at dose of 0.003, 0.01 and 0.03 mg/kg/day for three and six months induced no significant changes in the rats. At 0.1 and 0.3 mg/kg/day, however, some dose-dependent symptoms such as suppression of body weight gain, emaciation, regressive changes in adrenals, lymphatic and hematopoietic tissues, decrease in circulating white blood cell and lymphocyte counts, which have been known as toxic effects of synthetic corticosteroids, were induced. The results indicates that the maximum no-toxic dose of clobetasone-17 butyrate was 0.03 mg/kg/day on this experimental condition. In the recovery test for two months no significant differences in the treated rats from controls were found, suggesting that the toxic effects were reversible in the animals treated at 0.3 mg/kg/day and lower than that.
Acute and subacute toxicities of clobetasone-17-butyrate, a new anti-inflammatory corticosteroid, were studied in mice and rats. In the acute toxicity tests intraperitoneal LD50 values of the drug were estimated to be around 5 g/kg for both sexes of mice, 1.51 g/kg for male and 1.66 g/kg for female rats. Subcutaneous and oral administration induced no fatal cases at dose of 3.6 (mice, s.c.), 2.6 (rats, s.c.) and 6.0 g/kg (mice and rats, p.o.). As for the toxic signs in both mice and rats after the i.p. and s.c. administrations, emaciation was marked, and atrophy of thymus, spleen and adrenals were observed. No marked symptoms, however, were induced in animals administered orally. In the subacute toxicity tests male and female rats were subcutaneously administered with the drug at daily doses of 0.01, 0.03, 0.1, 1.0, 10 and 100 mg/kg for one month. Dose dependent symptoms such as suppression in body weight gain, emaciation, regressive changes in adrenal, lymphatic and hematopoietic tissues, decrease in circulating white blood cell and lymphocyte counts, and increase in total cholesterol level of serum were induced in the rats administered at 0.1 mg/kg/day and more than that, indicating that the maximum nontoxic dose in this experimental condition was 0.03 mg/kg/day. In recovery tests it was observed that the rats, which had been administered with the drug at 1.0 mg/kg/day for one month, were almost normal two months after the final administration.
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