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Biomedical subjects

Y Kitamura

Publications and source records attributed to Y Kitamura.

At least 775 records · Page 43Linked to original sources
PubMed1981

Purification of cathepsin D from rabbit skeletal muscle and its action towards myofibrils.

Cathepsin D (EC 3.4.23.4) was purified from rabbit skeletal muscle using acetone-dried muscle powder as starting material. After the acetone-dried powder was extracted with 0.2 mM ATP, the extract was fractionated with acetone an subjected to DEAE-Sephadex A-50 and Sephadex G-100 column chromatography. Rechromatography on a Sephadex G-100 column resulted in a purified preparation. SDS-polyacrylamide gel electrophoresis of the purified enzyme showed one major band of 42,000 daltons and some bands of contaminants. Since gel filtration also indicated a value of 42,000 daltons for the enzyme, it was concluded that muscle cathepsin D has no subunit structure. The enzyme acted optimally towards myofibrils around pH3, resulting in the degradation of the myosin heavy chain and production of a 30,000-dalton component.

Animals↗
PubMed1981

Spleen colony-forming cell as common precursor for tissue mast cells and granulocytes.

The haematopoietic stem cells which produce colonies in the spleen of irradiated mice (CFU-S) can differentiate into erythrocytes, granulocytes, megakaryocytes and B lymphocytes. Although mast cell precursors are known to be present in the bone marrow, spleen, fetal liver and peripheral blood of mice, the relationship between the mast cell precursor and CFU-S has remained unclear. We have now made use of mice of two mutant genotypes to determine whether or not the tissue mast cell is a progeny of CFU-S. Giant granules of beige (C57BL/6-bg/bg, Chediak-Higashi syndrome) mice can be used for identification of the origin of both tissue mast cells and granulocytes, and WBB6F1-W/Wv mice are useful recipients because they lack tissue mast cells owing to a defect in mast cell precursors. We injected the cells from a single spleen colony into each WBB6F1-W/Wv mouse and demonstrated directly that the tissue mast cell is a progeny of CFU-S.

Animals↗
PubMed1981

Precursor of mast cells fixed in the skin of mice.

The presence and origin of mast-cell precursors fixed in the skin tissue of mice were investigated. Giant granules of beige (C57BL/6-bh'/bg', Chediak-Higashi syndrome) mice were used to distinguish different populations of mast cells. Pieces of the skin were grafted from the intact WBB6F1 (WB X C57BL/6)F1-+/+ mice into the back of the WBB6F1-+/+ mice which had been irradiated and injected with bone marrow cells of C57BL/6-bg'/bg'leads to +/+ chimeras). Although the number of mast cells in the skin grafts decreased after the transplantation, the mast-cell precursors circulating in the bloodstream of bg'/bg' leads to +/+ chimeras (bg'/bg' type) did not seem to enter into the skin grafts, because most of mast cells were of +/+ type after the recovery of mast-cell number to pregrafting levels. As a considerable proportion of +/+-type mast cells was labeled with 3H-thymidine, the recovery of mast-cell number in the grafts was attributed to the proliferation and differentiation of +/+-type precursor cells fixed in the skin tissue of the donor. On the other hand, the skin of WBB6F1-W/Wv mice seemed to be depleted of fixed precursors, because most of mast cells were of bg'/bg'-type in skin grafted from WBB6F1-W/Wv mice to bgJ/bgJ leads to +/+ chimeras. Since the fixed precursor cells which proliferate and differentiate into mast cells after skin grafting may be transferred to WBB6F1-W/Wv mice by bone marrow transplantation, such precursor cells seem to have been derived from the bone marrow.

Animals↗
PubMed1981

Adjuvant chemo-endocrine therapy for androgen-dependent mammary tumor in mice.

About 500 male DS mice grafted with androgen-dependent Shionogi carcinoma 115 (SC115) were used. When the tumor diameter reached about 20 mm (approximately 25 days after transplantation), excision of the tumor and/or castration were carried out. The injection of cyclophosphamide (80 mg/kg body weight X 3 at 7-day intervals) was started from the day after excision. In mice with excised tumor, adjuvant chemo-endocrine therapy was the most effective treatment examined; cumulative 120-day mortalities after transplantation of tumors in non-treated, adjuvant endocrine therapy, adjuvant chemotherapy and adjuvant chemo-endocrine therapy groups were 91%, 29%, 21% and 0%, respectively. Castration induced development of clusters of androgen-independent cancer cells in androgen-dependent SC115 tumor. In mice without tumor excision, the chemo-endocrine therapy was again the most effective treatment, though 86% of mice died by the 120th day after tumor transplantation. These findings suggest the usefulness of adjuvant chemo-endocrine therapy for achieving complete remission in hormone-dependent tumors.

Androgens↗
PubMed1981

Absence of increase of histidine decarboxylase activity in mast cell-deficient W/W mouse embryos before parturition.

The histidine decarboxylase (L-histidine carboxylase, EC 4.1.1.22) activity of whole W/W mouse embryos, which are devoid of mast cells, remained very low and did not show the rapid increase before birth (17-20 days of gestation) seen in wild-type +/+ embryos. During the same period, the histamine content also remained very low and no mast cells were detected in the W/W embryos, in the contrast to the large increase in both histamine content and number of mast cells in wild-type embryos. These findings imply that the histamine in embryos is largely derived from mast cells. In +/+ mice, histidine decarboxylase activity decreased rapidly soon after birth without concomitant decrease in histamine content or number of mast cells, suggesting that the enzyme activity in mast cells is regulated by some unknown mechanism.

Age Factors↗
PubMed1981

Difference between magnesium and manganese ions in modification of effect of catecholamine on adenylate cyclase system in Ehrlich ascites tumor cells.

Involvement of divalent cations was examined in the activation of catecholamine sensitive adenylate cyclase in Ehrlich ascites tumor cells. In the presence of various concentrations of either Mg2+ or Mn2+, both basal and norepinephrine-stimulated, adenylate cyclase activities were measured. Both activities were gradually increased with the increase in Mg2+ concentration. On the other hand, with Mn2+, both activities were maximum at the low (2.5 mM) concentration, and decreased at the highest concentrations, the decrease being marked in the norepinephrine-stimulated activity. Similar difference between the two divalent cations was also observed in the effect on the binding of the beta-adrenergic ligand to the membrane receptor.

Adenylyl Cyclases↗
PubMed1981

Mechanism of hypercholesterolemia in arteriolipidosis-prone rats (ALR).

The cholesterol metabolism of a newly established model for atherogenesis, named arteriolipidosis-prone rats (ALR), selected from spontaneously hypertensive rats (SHR), was investigated in comparison with a substrain of SHR (B) (nonarteriolipidosis-prone rats) and the normotensive control. Wistar-Kyoto (WK) rats. Serum cholesterol of ALR was significantly lower than that of WK. Uptake of labelled serum cholesterol by the isolated liver cells at 37 degrees C was higher in ALR than in WK. The data for SHR (B) fell in between these two. On the other hand, on feeding a cholesterol diet, serum cholesterol increased in the order WK, SHR (B) and ALR, with the highest being ALR. The absorption of cholesterol in ALR was about twice as great as in WK and SHR (B).

Animals↗
PubMed1981

Migration of stromal cells supporting mast-cell differentiation into open wound produced in the skin of mice.

Mutant mice of Sl/Sld genotype are depleted of tissue mast cells due to a defect of stromal cells which may support the differentiation of mast cells. Number of mast cells did not increase in the skin of Sl/Sld mice grafted on the back of the congenic +/+ mice even 50 weeks after the transplantation. When the wound was produced in the central part of the Sl/Sld skin graft, a considerable number of mast cells appeared within the scar resulting from the wound. The appearance of mast cells in the scar was shown to be due to the differentiation of circulating precursors into mast cells rather than the simple migration of mature mast cells by using giant granules of bgJ/bgJ mice as a marker for newly-formed mast cells. Therefore, the present results seem to suggest that normal stromal cells of the +/+ host origin migrate into the wound produced in the grafted skin of Sl/Sld mice and support the differentiation of circulating precursors into mast cells.

Anemia, Macrocytic↗
PubMed1981

Hemopoiesis in cultures of the bone marrow cells from genetically anemic mice.

An attempt was made to reproduce the in vivo situation of the hemopoiesis in genetically anemic mice in vitro. Cultures of the bone marrow cells from W/Wu, Sl/Sld and control (+/+) mice revealed that all of the hemopoietic stem cells in these mice could be maintained in vitro as well. Similar results were also obtained with the spleen cell cultures. Since these anemic mice have near normal levels of committed progenitor cells, and pluripotent stem cells in Sl/Sld mice, and a subnormal level of functional blood cells sufficient for the survival of the mice, there should be a slow and constant hemopoiesis, under normal conditions. Such a slow but steady production of hemopoietic cells appears to be well reproduced in vitro.

Anemia↗
PubMed1980

Spontaneous stomach ulcer in genetically mast-cell depleted W/Wv mice.

Histamine has been implicated in the pathogenesis of gastroduodenal ulcers. Since mast cells contain a considerable amount of histamine as well as heparin and other biologically active substances, it seems reasonable to speculate that they are involved in this process. In fact, development of gastroduodenal ulcers was reported in dogs with mastocytoma, and an increase in mast-cell number was described in the vicinity of human gastroduodenal ulcers. Y.K. et al. have recently found that the number of mast cells in a unit length of the skin of W/Wv mutant mice is less than 1% of the value for the congeneic +/+ mice and that no mast cells are detected in the intestinal canal of W/Wv mice. Therefore, this mutant mouse was used to investigate the role of mast cells in the induction of gastroduodenal ulcers. As a preliminary experiment, we examined the stomach and duodenum of W/Wv mice without any treatments. Unexpectedly, we found the spontaneous development of perforating stomach ulcers in W/Wv mice, suggesting that mast cells do not necessarily have aggravating effects on the production of stomach ulcers.

Age Factors↗