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Biomedical subjects

M Miyamoto

Publications and source records attributed to M Miyamoto.

At least 649 records · Page 36Linked to original sources
PubMed1977

Studies on lymph humoral factor. Biological characteristics of a lymphocytopoietic factor in rat thoracic duct lymph.

The biological characteristics of a lymphocytopoietic factor obtained from rat thoracic duct lymph (Yamashita, Fukumoto & Miyamoto, 1976) were further investigated. The lymph extract from normal rats failed to stimulate both large pyroninophilic cell-proliferation and mitotic response in the spleen and lymph node of the thymectomized, irradiated and marrow reconstituted rat (B rat). This suggests that target or responsive cells for the factor are not marrow-derived (B) cells, but thymus-derived (T) cells. On the other hand, the lymph extract from the lymphopenic lymph-drained B rats showed similar high lymphopoietic activity to those of normal rats, indicating that the existence of a thymus is not essential for the production or secretion of the factor. The fact that lymphocytotic rats produced by syngeneic lymphocyte transfusion are most sensitive to the lymph extract suggests that liver endogenous level of this factor and the responsiveness of target cells are regulated by the number of circulating T lymphocytes.

Animals↗
PubMed1976

Metabolism in rats and man of piromidic acid, a new antibacterial agent.

1. Metabolism of the antibacterial, piromidic acid (5,8-dihydro-8-ethyl-5-oxo-2-pyrrolidinopyrido[2,3-d]pyrimidine-6-carboxylic acid) was investigated in rats and human subjects. Ten metabolites and the unchanged drug were found in the urine and the bile of both species after oral administration. 2. Metabolites were identified by comparison with authentic materials, except for the unstable metabolite, M-VI, for which a probable structure is proposed. The metabolic pathway of piromidic acid involved hydroxylation in the pyrrolidine ring to give the 2- and 3-hydroxy-derivatives (M-II and M-V). M-II was further metabolized to the corresponding gamma-aminobutyric acid derivative (M-IV) and the 2-5-dihydroxypyrrolidine derivative (M-VI) which was further metabolized to the 2-amino-pyridopyrimidine carboxylic acid (M-III). Piromidic acid, M-V, M-II, M-III and M-IV were partly excreted as respective glucuronides. 3. Metabolites, except glucuronides, exhibited antibacterial activity; M-V and M-II showed greater activity than piromidic acid. 4. The metabolism of piromidic acid is discussed in relation to the physicochemical properties of the drug and its metabolites.

Animals↗
PubMed1976

Studies on lymph humoral factor. Evidence for a lymphocytopoietic factor in rat thoracic duct lymph.

Normal rats were injected with the partially purified material extracted from the thoracic duct lymph which was collected from normal syngeneic rats. The cellular changes in the peripheral lymphoid tissues and thymus were examined cytologically and histologically. The intravenous injection of the lymph extract into normal syngeneic rats resulted in increase in weight of lymphoid tissues. Histologically, a massive proliferation of large pyroninophilic lymphoid cells and an increase in mitotic index was detected predominantly in the thymus-dependent areas and thymic cortex. In spleens from rats injected with lymph extract, the marginal zone bridging channel was shown as one route for the translocation or mobilization of newly borne lymphoid cells to the venous circulation. Similar lymphocytopoietic activity, but to a lesser extent than lymph extract, was also detected in lymph plasma, serum and serum extract. The lymph extract was shown to be non-immunogenic in syngeneic rats. It is suggested that the effects of the lymph extract on lymphoid cell proliferation are due to the presence of a lymphocytopoietic factor in body fluid, particularly in the lymph.

Animals↗