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Biomedical subjects

T Ohsawa

Publications and source records attributed to T Ohsawa.

At least 91 records · Page 5Linked to original sources
PubMed1985

Fractionation of newly replicated nucleosomes by density labeling and rate zonal centrifugation for the analysis of the deposition sites of newly synthesized nucleosomal core histones.

We have found that partial resolution of newly replicated nucleosomes can be achieved by rate zonal centrifugation through sucrose density gradients preformed in heavy water. Nucleosome samples were obtained from MH-134SC cells density labeled with 5-iododeoxyuridine in the presence of suitable isotopic precursors. The method is simple and can be performed under conditions that do not destabilize the nucleosome structure. This gave us an exciting opportunity to study the deposition sites of newly synthesized histones. Nucleosomes were obtained from cells pulse-labeled simultaneously with 5-iododeoxyuridine and [3H]lysine for the rate zonal analysis. Proteins in the resulting fractions were resolved by sodium dodecyl sulfate/polyacrylamide gel electrophoresis, and visualized by silver staining and fluorography. The distribution of newly synthesized H2A and H2B coincided closely with that of bulk nucleosomes. The distribution of newly synthesized H3 and H4 was shifted to the bottom sides of the bulk nucleosome peaks, but not so far as to the putative peaks of newly replicated (dense) nucleosomes. This means that newly synthesized histones are deposited on DNA in disproportionate amounts and that their sites of deposition are not restricted to newly replicated DNA.

Binding Sites↗
PubMed1985

Immunochemical measurement of histone H3 in non-nucleosomal compartments of cultured mammalian cells.

We measured histone H3 in the non-nucleosomal compartment of cultured mammalian cells by enzyme-linked immunoelectrotransfer blot assay of cytosolic proteins using affinity-purified rabbit anti-H3 IgG, and peroxidase-linked second antibodies. The cytosolic H3 level was estimated to be 0.5-1.0% of the nucleosomal H3 content in MH-134SC cells (mean generation time 11 h) and 3-4% in HeLa cells (mean generation time 22 h). It showed characteristic changes under the inhibitions of DNA and/or protein synthesis and during the cell cycle of HeLa cells. These indicate an inverse relationship between the cytosolic H3 level and the replicating activity of nuclear DNA. The possible implication of the non-nucleosomal histones in the regulation of histone gene expression is discussed.

Animals↗
PubMed1985

Hepatitis associated with allopurinol.

When adverse reactions occur, it is important to identify the etiologic drug. We describe a case of hepatitis associated with allopurinol. A 66-year-old female was admitted for rehabilitation of a cerebral hemorrhage on September 11, 1981. Allopurinol, clofibrate, and baclofen were administered. Severe hepatitis developed on November 13. The clinical laboratory data returned to normal on November 30. Challenge tests were conducted on clofibrate, allopurinol, and baclofen. The challenge test was positive after the administration of allopurinol. Allopurinol hepatitis is most likely a hypersensitivity reaction, as is suggested by the symptoms of eosinophilia and rash. Renal dysfunction may predispose one to develop hepatitis associated with allopurinol.

Aged↗
PubMed1984

Alteration of ceramide monohexoside in human diploid fetal lung fibroblasts during cell aging.

Serially cultured human diploid fibroblasts have a finite lifetime in vitro, and this phenomenon was postulated as cellular aging. Neutral glycosphingolipids (GSLs) from human fetal lung-derived diploid fibroblast cell lines, WI-38 and TIG-1 cells, were studied during cellular aging. Both cell lines had at least four types of neutral GSLs. It was found that neutral GSLs changed with aging, the most conspicuous alteration being a 2-4-fold increase in the content of ceramide monohexoside. This change was invariably observed in either WI-38 or TIG-1 cells.

Cell Line↗