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Biomedical subjects

Y Kitamura

Publications and source records attributed to Y Kitamura.

At least 631 records · Page 35Linked to original sources
PubMed1987

Differentiation and transdifferentiation of mast cells; a unique member of the hematopoietic cell family.

Information about the differentiation of mast cells has increased remarkably in the past ten years. This progress has resulted from the introduction of techniques which developed in other fields of experimental hematology. Once mast cells were recognized as a progeny of multipotential hematopoietic stem cells, their unique differentiation processes were clarified. Although most of the progeny of stem cells leave the hematopoietic tissue after maturation, undifferentiated precursors of mast cells leave the hematopoietic tissue. Morphologically, unidentifiable precursors migrate in the bloodstream, invade the connective tissues or the mucosa of the alimentary canal, proliferate, and differentiate into mast cells. Even after their morphological differentiation, some mast cells retain an extensive proliferative potential. There are at least two subpopulations of mast cells: a connective-tissue type and a mucosal type. Connective tissue-type and mucosal mast cells can be distinguished by histochemical, electron microscopical, biochemical and immunological criteria; however, these two types can interchange, and their phenotypes are determined by the anatomical microenvironment in which their final differentiation occurs. Although biochemical natures of the anatomical microenvironment are unknown, molecules that support proliferation and differentiation of mast cells in vitro have been characterized, i.e., interleukin 3 and interleukin 4. In the next ten years, increased information about the differentiation processes will probably induce further understanding of mast cell functions.

Animals↗
PubMed1987

Characteristics of murine yolk sac erythroid progenitors and their population expansion in liquid culture.

Remarkable differences were found between late erythroid progenitors (CFU-e) in cultures of murine yolk sac cells and those of fetal liver cells with respect to frequency, erythropoietin responsiveness and colony size. Cultures of yolk sac on day 11 of gestation showed a CFU-e population of lower frequency, less sensitivity to erythropoietin and smaller colony size than those from cultures of day 14 fetal liver cells. As the proportion of CFU-e to BFU-e was much lower in yolk sac than that in fetal liver, 48-96 h liquid culture experiments were done with these cells to examine the capacity of their precursors to generate a certain amount of CFU-e subpopulations. The cultures of yolk sac cells produced large numbers of CFU-e which formed some large-sized colonies but those of fetal liver cells generated only a small amount of CFU-e.

Animals↗
PubMed1987

Frequent overexpression, but not activation by point mutation, of ras genes in primary human gastric cancers.

To define the extent of involvement of ras oncogenes in human gastric cancers, we surveyed for the presence of ras oncogenes, activated by either point mutations within their coding sequences or overexpression of ras protein p21, by the combined use of several analytic techniques. Primary gastric cancers were first analyzed by deoxyribonucleic acid transfection assay using NIH/3T3 cells as recipients and by restriction enzyme analysis, which detects point mutations at codon 12 of the H-ras gene. None of seven tumors analyzed scored as positive. Furthermore, none of them had ras p21 with altered electrophoretic mobility on immunoprecipitation and Western blotting, confirming the absence of ras oncogenes activated by point mutations in these tumors. However, in 6 of 7 tumors, the amounts of p21 exceeded that in human placenta. Amplification of the K-ras gene was found in 1 of 11 (including the 7 described above) gastric cancers. Immunohistochemical analysis of ras p21 expression in these 11 tumors was then carried out using the anti-ras p21 monoclonal antibody RAP-5. All cancers showed more reactivity with RAP-5 than did normal mucosa adjacent to the cancers, indicating increased expression of ras p21. These results indicated that transformation of the stomach mucosa from the normal to the malignant phenotype is rarely associated with activation of ras genes by point mutations, but is frequently associated with enhanced expression of ras p21.

Adenocarcinoma↗
PubMed1987

Roles of neonatal and prepubertal testicular androgens on androgen-induced proliferative response of seminal vesicle cells in adult mice.

Male mice were castrated at 0, 10, 20, 30, 40 and 60 days of age; daily injections of testosterone propionate (TP, 4 micrograms/g b. wt) were started from day 90. On various days after starting the TP injections, the incorporation of 5-[125I]iodo-2'-deoxyuridine into the whole seminal vesicles was determined as an index for proliferation. The seminal vesicle cells in mice castrated on days 0 and 20 were characterized by low weight (0.5-1 mg) before TP injection, long duration of androgen-induced proliferation (greater than 20 days) with a low peak, and involvement of both epithelial and fibromuscular cells (neonatal castration type). The seminal vesicle cells in mice castrated on days 60 and 40 were characterized by relatively high weight (5-10 mg) before TP injection, short duration of androgen-induced proliferation (10 days) with a high peak, and involvement of only the epithelial cells (adult castration type). In mice castrated on days 0 and 20, the neonatal castration type of androgen-induced proliferation was completely changed to the adult castration type when TP pretreatment (2 micrograms/g b. wt per 12 h) had been given from day 20 to day 40. However, the TP pretreatment given from day 90 to day 110 instead of days 20-40 had no such effect in 140-day old mice castrated on day 0. The present findings suggest that testicular androgens secreted from day 20 to day 40 play an indispensable role in the induction of irreversible proliferative response of the mouse seminal vesicle. The activity of the prepubertal androgens may not be completely compensated by androgen activity at adulthood.

Androgens↗
PubMed1987

Effect of long term androgen removal on androgen-induced proliferation of seminal vesicle cells in adult mice.

Male mice were castrated on day 60 after birth; daily injections of testosterone propionate (TP, 4 micrograms/g b.wt) were started 1.2 or 6 months after the castration. The incorporation of 5-[125I]iodo-2'-deoxyuridine [( 125I]IdUrd) into the whole seminal vesicles was determined on various days after starting the TP injections as an index for proliferation. Although the peak of [125I]IdUrd uptake was observed 3 days after starting the TP injections in both short (1-2 months) and long (6 months) term castrated mice, the peak was significantly lower and the period of proliferation was longer in the long term group than in the short term group; the weights of seminal vesicles before TP injections were 6 and 10 mg in the long and short term groups, respectively. Although TP injections induced the proliferation of only epithelial cells in the short term group, the same treatment induced the proliferation of both epithelial and fibromuscular cells in the long term group. The deficient responsiveness to androgen of the seminal vesicle cells found in the long term castrated mice was completely recovered by TP pretreatment for 2 weeks. The present findings suggest that so-called imprinted cells in the mouse seminal vesicle induced by neonatal and prepubertal testicular androgens are very slowly lost at least in part by androgen removal for long periods such as more than 6 months in adult mice and that the loss is at least in part due to the death of fibromuscular cells, which is recovered rather quickly by androgen pretreatment.

Aging↗
PubMed1987

Accelerated glycation of the aorta in diabetic rats.

Glycation of the aorta in rats with streptozotocin-induced diabetes was estimated by determining the early-stage product and the advanced product of the Maillard reaction. The early-stage product of the Maillard reaction was determined using furosine, which is derived from glycated lysine residues by acid hydrolysis. The advanced product was determined by fluorescence high-performance liquid chromatography. The levels of both early-stage and advanced products in diabetic rats were significantly higher than those in non-diabetic rats at the age of both 20 and 50 weeks. The levels of both early-stage and advanced products at 50 weeks in rats tended to be higher than those at 20 weeks. However, the level of glycated hemoglobin in both non-diabetic and diabetic rats showed no significant change between 20 and 50 weeks of age. These results suggest that tissue glycation may be involved in the development of diabetic complications and may be related to the aging mechanism.

Animals↗
PubMed1987

Induction of histidine decarboxylase in non-mast cells in the spleen of mice by injection of staphylococcal enterotoxin A.

Injection of Staphylococcal enterotoxin A (SEA) into WBB6F1-W/WV mice genetically deficient in mast cells resulted in a 10-fold increase in the histidine decarboxylase [HDC, L-histidine carboxylase, EC 4.1.1.22] activity of their spleen. The nature of the spleen cells responsible for this increased HDC activity was studied. The HDC induction by SEA was abolished on day 1 after X-ray irradiation of the mice at 400 rad and restored by transplantation of bone marrow cells from normal WBB6F1-+/+ littermates into the X-ray irradiated WBB6F1-W/WV mice. Transplantation of cells from other organs of the normal mice, such as the thymus, mesenteric lymph node and spleen, did not restore the HDC increase significantly. Transplantation of cultured mast cells also did not restore the increase. Moreover, the high HDC activity of spleen cells induced by SEA was not affected by their treatment with anti-Thy-1,2 antibody and complement. Depletion of phagocytes from the spleen by treatment with carbonyl iron resulted in decrease in HDC activity. These results suggested that phagocytic cells derived from haemopoietic stem cells of the bone marrow were responsible for the increase in HDC activity induced by SEA.

Animals↗
PubMed1987

Maintenance of granulopoiesis in long-term bone marrow cultures from W/Wv mice and effects of lipopolysaccharide on granulopoiesis in culture.

An attempt was made to establish long-term cultures of marrow cells from genetically anaemic W/Wv mice. Two batches of horse sera were used. One batch of horse serum (HS-lot A) supported long-term maintenance (up to 20 weeks) of granulopoiesis in vitro. The number of suspension cells in W/Wv marrow culture was maintained at the same level as that in the control +/+ culture, but the number of granulocyte-macrophage progenitor cells (GM-CFC) and the ratio of immature to mature granulocytes were at a lower level than those in +/+ culture. These data suggest that haemopoietic progenitors in W/Wv cultures maintain a higher level of differentiation, and hence an increased self-renewal than those in +/+ cultures. Another batch of horse serum (HS-lot B) was less effective in the maintenance of the cultures, and the cultures deteriorated within 10 weeks. Addition of bacterial lipopolysaccharide (LPS) induced increased granulopoiesis in +/+ cultures, whereas such treatment resulted in the depletion of suspension cells in W/Wv cultures. The results suggest that haemopoietic cells of W/Wv mouse cannot cope with the strong stimulus for differentiation that occurs after the administration of LPS, although the cells can continue a moderately increased self-renewal and differentiation, as indicated by the results in the culture with HS-lot A.

Anemia, Macrocytic↗
PubMed1987

Uncoupling of rat cerebral cortical alpha 2-adrenoceptors from GTP-binding proteins by N-ethylmaleimide.

Pretreatment of membranes from rat cerebral cortex with N-ethylmaleimide (NEM) decreased [3H]-clonidine binding in a concentration-dependent manner. The Bmax values of high-affinity sites for [3H]clonidine were reduced by 50 microM NEM treatment. Treatment with 500 microM NEM diminished the sum of Bmax of both high- and low-affinity components. GTP, Na+, and Mn2+ exerted little effect on [3H]clonidine binding in NEM-treated membranes. The addition of purified GTP-binding proteins caused an increase in the binding to the membranes pretreated with 50 microM NEM, but did not increase [3H]-clonidine binding in membranes treated with 500 microM NEM. In contrast, NEM pretreatment inhibited islet activating protein (IAP)-catalyzed ADP ribosylation of membrane-bound (41,000-dalton) and purified (39,000/41,000-dalton) GTP-binding proteins. From these results, it is suggested that two or three categories of essential sulfhydryl groups are involved in the coupling between agonist, alpha 2-adrenoceptor, and GTP-binding protein. One is a highly sensitive site to NEM (a concentration range of 1-50 microM), which is probably a cysteine residue, IAP-catalyzed ADP-ribosylating site on the alpha-subunit of GTP-binding protein. Other sites have low sensitivity to NEM (a concentration range of 0.1-1 mM), and are the binding domain of agonist and/or the coupling domain of GTP-binding protein on the alpha 2-adrenoceptor. In addition, Ki-ras p21 protein may lack the capacity to couple with the alpha 2-adrenoceptor.

Adenosine Diphosphate Ribose↗
PubMed1987

Mutual phenotypic changes between connective tissue type and mucosal mast cells.

Connective tissue mast cells (CTMC) and mucosal mast cells (MMC) are apparently different, but the ontologic relationship between these two types of mast cells was unclear. We investigated the relationship by combining in vivo and in vitro techniques. Although bone marrow-derived mast cells developed in suspension culture resemble MMC, they acquired histochemical, electron microscopical, biochemical and immunological characteristics of CTMC after the transfer into the peritoneal cavity of genetically mast cell-deficient WBB6F1-W/Wv mice. On the other hand, when single peritoneal mast cells (typical CTMC) of WBB6F1-+/+ mice were injected into the stomach wall of WBB6F1-W/Wv mice, CTMC appeared in the muscularis propria and MMC in the mucosa. These results suggest that CTMC and MMC may interchange and that their phenotypes are determined by the anatomical microenvironment in which the final differentiation occurs.

Animals↗
PubMed1987

Long-term monoclonal reconstitution of erythropoiesis in genetically anemic W/Wv mice by injection of 5-fluorouracil-treated bone marrow cells of Pgk-1b/Pgk-1a mice.

The spleen colony-forming assay does not represent the number of hematopoietic stem cells with extensive self-maintaining capacity because five to 50 spleen colony-forming units (CFU-S) are necessary to rescue a genetically anemic (WB X C57BL/6)F1-W/Wv(WBB6F1-W/Wv) mouse. We investigated which is more important for the reconstitution of erythropoiesis, the transplantation of multiple CFU-S or that of a single stem cell with extensive self-maintaining potential. The electrophoretic pattern of hemoglobin was used as a marker of reconstitution and that of phosphoglycerate kinase (PGK), an X chromosome-linked enzyme, as a tool for estimating the number of stem cells. For this purpose, we developed the C57BL/6 congeneic strain with the Pgk-1a gene. Bone marrow cells were harvested after injection of 5-fluorouracil from C57BL/6-Pgk-1b/Pgk-1a female mice in which each stem cell had either A-type PGK or B-type PGK due to the random inactivation of one or two X chromosomes. When a relatively small number of bone marrow cells (ie, 10(3) or 3 X 10(3] were injected into 200-rad-irradiated WBB6F1-W/Wv mice, the hemoglobin pattern changed from the recipient type (Hbbd/Hbbs) to the donor type (Hbbs/Hbbs) in seven of 150 mice for at least 8 weeks. Erythrocytes of all these WBB6F1-W/Wv mice showed either A-type PGK alone or B-type PGK alone during the time of reconstitution, which suggests that a single stem cell with extensive self-maintaining potential may sustain the whole erythropoiesis of a mouse for at least 8 weeks.

Anemia↗
PubMed1987

Frequency of active ras oncogenes in human bladder cancers associated with schistosomiasis.

The frequency of active ras oncogenes in human bladder cancers associated with schistosomiasis, the cause of which is suspected to be a chemical carcinogen(s) in urine, was examined. Of 9 squamous cell carcinomas of the bladder surgically obtained in Egypt, none scored as positive in the regular DNA transfection assay using NIH/3T3 cells as recipients. The restriction fragment length polymorphism assay at codon 12 of the H-ras gene confirmed the absence of an activating mutation at this site in all of them. Western blotting analysis of electrophoretic mobilities of the ras p21 proteins, a method which can detect at least some of the point mutations within codons 12 and 61 of ras genes, suggested a point mutation within codon 61 in one out of the 7 tumors analyzed. In contrast to the low frequency of detection of mutationally activated ras oncogenes, enhanced expression of the ras p21 proteins was demonstrated in 4 of them by this analysis. The carcinogenic process involved in the endemic bilharzial bladder cancers is thus not associated with detectable point mutations within ras genes at a higher frequency than those in non-bilharzial bladder cancers in Japan or the USA.

Animals↗