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Biomedical subjects

S Iguchi

Publications and source records attributed to S Iguchi.

At least 91 records · Page 5Linked to original sources
PubMed1981

Acetylator phenotype and metabolic disposition of isoniazid in Japanese patients with systemic lupus erythematosus.

Acetylator phenotype and metabolic disposition of isoniazid (INH) were studied in 19 Japanese (a population shown to be 11.5% slow acetylators) patients with spontaneous systemic lupus erythematosus (SLE) and 19 healthy controls. Subjects with the elimination half-life (t1/2) of INH of 2.0 hours or less were considered rapid and those of 2.2 hours or more were slow acetylators. Results of phenotyping showed that 17 of 19 SLE patients were rapid, 1 slow, and 1 indeterminate, whereas 18 of the controls were rapid and 1 indeterminate. When phenotyped according to another reported antimode (107 or 110 minutes), 3 of the patients and 2 of the controls were slow and the remainder were all rapid acetylators. The distribution of INH t1/2, acetyl INH to INH ratios in urine and plasma, and hydrazine compounds in urine measured with gas chromatography mass spectrometry was similar between the two groups, except for 1 patient who was definitely classified as a slow acetylator. The relationship between phenotype distribution and possible pathoetiologic factors is discussed.

Acetylation↗
PubMed1981

Metabolism of isoniazid and free hydrazine formation in isolated rat hepatocytes.

Isoniazid (INH) was incubated with isolated rat hepatocytes, and the amounts of acetyl-INH, monoacetylhydrazine, diacetylhydrazine and hydrazine formed were determined by gas chromatography-mass spectrometry (GC-MS). Subsequent analyses of kinetic parameters of metabolic pathways and enzymological study of rat liver homogenate revealed that hydrazine was formed preferentially from INH, catalyzed by soluble hydrolytic enzymes.

Animals↗
PubMed1981

Characteristic biotransformation of aminopyrine in rat when administered with barbital.

After the administration of aminopyrine with or without barbital to rats, aminopyrine and its main metabolites were detected in plasma and the brain by means of gas chromatography-mass spectrometry. It was clarified that a marked increase of 4-monomethylaminoantipyrine was observed in the case of coadministration of aminopyrine and barbital, while the plasma level of aminopyrine decreased significantly compared with single administration.

Aminopyrine↗
PubMed1981

Tissue distribution of isoniazid and its metabolites in rats.

Distribution of isoniazid and its metabolites was observed in the liver, kidney, lung and plasma after the subcutaneous administration of isoniazid to rats. The tissue levels of isoniazid, acetylisoniazid, acetylhydrazine, 1,2-diacetylhydrazine and hydrazine were determined by mass fragmentography using a gas chromatograph-mass spectrometer equipped with a multiple ion detector-peak matcher. Using the compounds labeled with a stable isotope as an internal standard, namely the isotope dilution method, made it possible to estimate trace amounts of these metabolites in the tissues. The amount of hydrazine was much less than the other hydrazines, but the metabolite which is well known as a mutagen, could be successfully detected in the tissues and plasma. The greater part of free hydrazine is formed through a direct hydrolysis of isoniazid. The isoniazid-hydrolyzing activity was found to be significantly higher in the liver homogenate. This suggested that hydrazine formation is mainly caused by hepatic hydrolysis.

Absorption↗
PubMed1981

Occurrence of two distinct subpopulations of suppressor cells in rats bearing chemically induced tumors.

Spleen cells from rats bearing syngeneic methylcholanthrene-induced sarcomas showed impaired proliferative responses to phytohemagglutinin (PHA) as well as to the KCl tumor extract. Studies were then performed to define suppressor cell systems possibly operating in tumor-bearing rats. For this purpose, thymus and spleen cells from tumor-bearing rats were admixed with tumor-immune or normal rat spleen cells and were assayed for their suppressing activity on proliferative responses of immune spleen cells to the tumor antigens and on those of normal spleen cells to PHA. Anti-rat T cell serum and glass-adherent technique were utilized to characterize the cellular source of suppressor activity in the thymuses and spleens of tumor-bearing rats. The results indicate that there are two distinct subpopulations of suppressor cells in tumor-bearing rats. The first is glass-adherent non-T suppressor cells that inhibit lymphocyte proliferative responses both to the tumor antigens and to PHA. The second is suppressor T cells and can only impair proliferative responses of tumor-immune lymphocytes to the tumor antigens. The former cells were found in tumor-bearers' spleens, while the latter cells were present in their thymuses and spleens. It is suggested from these data that complex mechanisms of immunosuppression are working in tumor-bearing hosts, one of which can be attributed to the existing suppressor cells in those host lymphoid tissues.

Animals↗
PubMed1981

[Mechanism of suppression on cellular immunity in experimental brain tumor rats (author's transl)].

The mechanism of the suppression on the cellular immunity was analysed in experimental brain tumor rats. The tumor used in this experiment was a 3-methylcholanthrene induced fibrosarcoma. The tumor cell was inoculated into the caudate nucleus of the rats with a Hamilton microsyringe. When spleen cells from brain tumor rats were added to the PHA blastogenesis system, impairment of the normal lymphoproliferative response to the PHA was detected as early as on the third day and continued until the ninth day after inoculation. After the depletion of glass adherent cells, the residual cells from the spleen could not suppress the normal lymphoblastogenesis by the PHA. After the depletion of T cells by anti-T cell sera and complement, however, the residual cells from the spleen still suppressed the normal lymphoblastogenesis. Glass adherent cells were able to phagocyte the latex particles. From these findings, the suppressor cell responsible for the suppression of the normal lymphoblastogenesis by the PHA was considered to be macrophage and suppressor T cell did not play a role in the suppression of the PHA responses in this experimental model. The sera from brain tumor rats could not inhibit the proliferative responses of lymphocytes to PHA. Thus the possibility of the existence of suppressive factors in the sera was also negligible.

Animals↗
PubMed1980

An NADP-linked prostaglandin D dehydrogenase in swine brain.

An NADP-linked 15-hydroxyprostaglandin dehydrogenase specific for prostaglandin D2 was discovered and partially purified from cytosol of swine brain. Prostaglandins A2, B2, D3, E2, and F2 alpha were poor substrates for this enzyme, the rates of reaction being less than 10% of that with prostaglandin D2. The enzyme was separated by Sephadex column chromatography from the other NADP-linked 15-hydroxyprostaglandin dehydrogenase that was also present in brain and metabolized prostaglandins B2, E2, and F2 alpha much more effectively than D2. The primary reaction product was tentatively identified as 15-ketoprostaglandin D2 by its characteristic absorption spectrum with a peak at 415 nm at pH 9. This compound was further converted to 13,14-dihydro-15-ketoprostaglandin D2 in the presence of NADPH by the action of 15-ketoprostaglandin delta 13-reductase that was co-purified with the dehydrogenase. This dehydrogenase appears to be responsible for the specific inactivation of prostaglandin D2 which is the major prostaglandin in the central nervous system.

Animals↗