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Biomedical subjects

Y Mitsui

Publications and source records attributed to Y Mitsui.

At least 307 records · Page 17Linked to original sources
PubMed1982

Life span of the wild and mutant nematode Caenorhabditis elegans. Effects of sex, sterilization, and temperature.

The survival of Caenorhabditis elegans was studied comparing animals of different sexes, sterilized animals, and animals grown at different temperatures as a prelude to more detailed cytological and genetic analysis of aged nematodes. Temperature-sensitive sterile mutants, animals sterilized by 5-fluorodeoxyuridine treatment, and wild-type males showed little difference in life span from that of wild-type hermaphrodites, although slight changes in P (time of beginning of the dying phase) or T1/2 (half-life of the population in the early dying phase) values were observed. At higher temperatures, P and T1/2 values markedly decreased, indicating a shortened life span. Temperature shift between 16 degrees C and 25 degrees C revealed that an increase in life span always involved low temperatures after the adult phase. High temperature treatment during the growing phase or after the adult phase caused an earlier start of the dying phase, but a downward temperature during the adult phase resulted in a great increase in the half-life of the population (T1/2). The results suggest that the life span of C. elegans is rigidly determined by somatic cells and markedly influenced by the effects of temperature on the cells during the post-mitotic state.

Animals↗
PubMed1982

Cytoprotective effect of cyclic AMP on cultured rabbit gastric cells.

A new experimental system with cultured gastric cells was developed to estimate the cytoprotective and damaging effects of drugs. The gastric cells were incubated in vitro in medium of pH 3, and their resistance to acid was determined by measuring percentage of damaged cells as a function of time. Pretreatment with 0.5 mM acetylsalicylic acid (ASA) for 24 h decreased their resistance (26%), whereas pretreatment with 0.3-3 micrograms/ml of 16,16-dimethylprostaglandin E2 (dimethyl PGE2) for 4 h increased their resistance (13-16%). The adenosine 3':5'-cyclic monophosphate (cyclic AMP) level in the cultured gastric cells was decreased by 0.5 mM ASA (30%) and increased by 0.3 microgram/ml of dimethyl PGE2 (38%) on treatment for 24 h. These changes reflect phenomena observed in the gastric mucosa, suggesting that this experimental system is valid as an in vitro model. Concentrations of 0.1 mM cyclic AMP and 0.1 mM N6, O2'-dibutyryladenosine 3':5'-cyclic monophosphate (dibutyryl cyclic AMP) were found to exert cytoprotective effects on the cells (5 and 7% increase, respectively). Furthermore, 0.1 mM cyclic AMP caused partial recovery from 0.5 mM ASA-induced decrease in resistance (ASA: 17%, ASA + cyclic AMP: 9%). These findings suggest that cyclic AMP plays a role in protection of cultured gastric cells and presumably also of gastric mucosal cells in vivo.

Animals↗
PubMed1982

Comparison of prostaglandin biosynthetic activity between porcine aortic endothelial and smooth muscle cells in culture.

Prostaglandin biosynthetic activity of miniature-pig aortic endothelial cells was compared with that of smooth muscle cells in culture. When used as homogenates, endothelial cells produced mainly PGE2 and 6-ketoPGF1 alpha (degradated product of PGI2) from arachidonic acid, while they produced a large amount of PGF2 alpha in addition to these when used as intact cells. Intact smooth muscle cells and their homogenates produced PGE2 as a major product. 6-KetoPGF1 alpha was produced by smooth muscle cells in the first few generations and became undetectable after several cultivations. 6-KetoPGF1 alpha and PGE2 were produced by intact or endothelium-depleted aortas. Our results suggest that both endothelial cells and smooth muscle cells in porcine aorta possess PGI2 and PGE2 biosynthetic activities. The subcultivation of smooth muscle cells, but not endothelial cells, in vitro resulted in the rapid disappearance of PGI2 synthetase activity. The PGI2 biosynthetic activity of endothelial cells was several fold higher than that of smooth muscle cells. Porcine smooth muscle cells' low ability to produce PGI2 may offer a reason why atherosclerosis is easily developed in pigs.

6-Ketoprostaglandin F1 alpha↗
PubMed1982

Preliminary chemical and X-ray studies on the interactions of E. coli DNA with putrescine.

The interactions of E.coli DNA with putrescine in aqueous solution and fiber were studied by melting temperature analysis, equilibrium dialysis and X-ray diffraction. The equilibrium binding of putrescine to DNA is shown, of which association constant is in the order of 10(3) 1/mol. The binding of putrescine stabilizes the B-form of DNA fiber and the crossbridge of putrescine in the intra-double helix is suggested by precipitate formation experiments of various polyamines with DNA.

Chemical Phenomena↗
PubMed1981

Changes in cell-surface glycosaminoglycans in human diploid fibroblasts during in vitro aging.

Changes in glycosaminoglycans during in vitro aging were investigated in human diploid fibroblasts. The cells were found to produce predominantly hyaluronate and smaller amounts of chondroitin 4-sulfate, chondroitin 6-sulfate, dermatan sulfate and heparan sulfate. Accumulation of heparan sulfate on the cell surface was notable during aging. Total glycosaminoglycan production in preconfluent culture did not change with population doubling level (PDL), while in confluent culture a decline in glycosaminoglycan production was observed. In contrast with this, heparan sulfate on the cell surface increased as a function of PDL in both confluent and preconfluent cultures. The distribution pattern of heparan sulfate in medium and cell surface indicated that the increase in heparan sulfate on the cell surface could be attributed to an increased accumulation on the cell surface, but not to an elevated production. Thus, we conclude that the increased accumulation of heparan sulfate on the cell surface might be involved in an age-related alteration in the cell membrane.

Cell Division↗
PubMed1981

Equivalent proliferation potential different size classes of human diploid fibroblasts.

Human diploid fibroblasts were separated on the basis of size by sedimentation at unit gravity in a 5 to 30% fetal bovine serum gradient. The larger cells sedimented faster and were comprised of a larger proportion of cells that failed to incorporate tritiated thymidine during the 48 hours prior to sedimentation. However, the large cells and small cells had the same long-term replicative ability as determined both by ability to form large clones and by the total number of population doublings accrued in citro. Even after refractionation the larger and smaller cells had the same long-term proliferation ability. These results indicate that, although old cultures contain a high proportion of large cells and cells not able to synthesize DNA during a 24 to 48 hour period, these parameters cannot be used to select subpopulations of cells with different proliferative potentials from young or late passage cultures.

Aging↗