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Biomedical subjects

Y Hashimoto

Publications and source records attributed to Y Hashimoto.

At least 1,459 records · Page 81Linked to original sources
PubMed1984

Induction of nonspecific killer T cells from non-immune mouse spleen cells by culture with interleukin 2.

Culture fluids of concanavalin A-stimulated rat spleen cells were purified by means of ammonium sulfate precipitation and Sephacryl S-200 column chromatography. Interleukin 2 (IL-2), which can promote the proliferation of mouse lymphocytes was distributed in the fractions of molecular weight of 22,000 to 26,000 daltons. Culture of C57BL/6 mouse spleen cells with the IL-2 fraction resulted in the induction of cells cytotoxic to syngeneic fibrosarcoma cells. Determination of the target specificity of the killer cells revealed that the killer cells could lyse a variety of syngeneic and allogeneic tumor cells in vitro. The results of cold target inhibition tests and cytotoxicity assay after treatment with antisera plus complement indicated that the killer cells mainly consisted of Thy 1.2+, Ly 2.2+, asialoGM1-T cells but included some asialo-GM1+ natural killer (NK) cells. Although the cytotoxicities of both IL-2-activated killer T cells and NK cells were nonspecific in terms of the antigen specificity, their cytotoxic activities against syngeneic fibrosarcomas and NK-sensitive allogeneic lymphomas were complementary. The assay of interferon in culture fluid from IL-2-treated spleen cells suggested that generation of IL-2-activated killer cells was closely associated with the amount of immune interferon released from lymphocytes in the culture.

Animals↗
PubMed1984

Mitogenic effect of IL 2 on non-thymic and thymic lymphocytes of the mouse.

Interleukin 2 (IL 2) was obtained from culture fluids of Con A-stimulated rat spleen cells and purified by repeated Sephacryl S-200 column chromatography. The purified IL 2 showed a direct mitogenic effect on C57BL/6 mouse spleen cells and lymph node cells but not on unfractionated thymocytes. Contamination of Con A in the IL 2 was ruled out by the finding that the mitogenic effect of the IL 2 was not diminished by addition of alpha-methyl-D-mannoside in the reaction mixture. The treatment of the spleen cells with anti-Thy 1.2 and complement abolished the response to the IL 2, indicating that the IL 2-responding cells bear a T cell marker. Although unfractionated thymocytes did not blastogenically respond to the IL 2, fractionation of thymocytes by means of discontinuous gradient centrifugation with Percoll resulted in a minor cell population which strongly responded to the IL 2 stimulation. The cells were distributed in lower density fractions. The cells distributed in higher density fractions did not respond to the IL 2.

Animals↗
PubMed1984

Different response of mouse thymocyte subpopulations to interleukin 2 and concanavalin A.

Fractionation of C57BL/6 mouse thymocytes by Percoll density gradient centrifugation resulted in three thymocyte subpopulations of different characters. The first population (Fr 1 cells) and both the second (Fr 2 cells) and the third (Fr 3 cells) populations mainly consisted of Thy 1.2+, Ly 1+, Ly 2-, PNA- cells and Thy 1.2+, Ly 1-, Ly 2+, PNA+ cells, respectively. Although all these subpopulations expressed Thy 1.2 alloantigen, its density on the cells was different and was high in the order of Fr 3, Fr 2, and Fr 1 cells. In terms of blastogenic response, Fr 1 cells were highly responsive to either IL 2 or Con A, but Fr 2 cells did not respond to Con A, unless IL 2 was present. Fr 3 cells were not responsive to Con A even in the presence of IL 2. When fractionated cells were cultured in normal culture medium for 12 h, the spontaneous incorporation of 3H-thymidine (SIT) into the cells was lowered in Fr 3 cells to a greater extent than was observed with Fr 1 and Fr 2 cells. These results indicated that the response of thymocyte subpopulations to IL 2 and/or Con A was closely related to the maturation stages of T cells and that Ly 1-, Ly 2+, PNA+ immature thymocytes might consist of two different subpopulations as indicated by their IL 2 response and the reduction of SIT capacity by culture.

Animals↗
PubMed1984

2-Aminodipyrido[1,2-a:3',2'-d]imidazole-porphyrin(Fe) derivatives as sequence specific DNA cleaving reagents.

Some porphyrin (Fe)-intercalators were synthesized. We chose 2-aminodipyrido[1, 2-a:3',2'-d]imidazoles (Glu-P's), which were muta-carcinogens isolated from a pyrolysate of L-glutamic acid, as intercalator moieties. These synthetic porphyrin (Fe)-intercalators cleave DNA at G-C and G-T sequences. The specificity for cleavage of base sequences of DNA is quite similar to that of bleomycin.

Aminopyridines↗
PubMed1984

Species difference between rats and mice in activities of enzymes activating aromatic amines: effect of dietary 3-methoxy-4-aminoazobenzene.

Male Donryu rats and B6C3F1 mice were treated with dietary 3-methoxy-4-aminoazobenzene (3-MeO-AAB) (0.06% or 0.09%), and subcellular fractions of the liver were examined for ability to mutagenically activate 3-MeO-AAB and 2 amino acid pyrolysate components using Salmonella typhimurium TA 98 as a tester strain. The treatment resulted in striking induction of enzyme(s) for the mutagenic activation of these aromatic amines in rats, but the effect was smaller in mice. The enzyme(s) involved in the reaction was characterized as an isotype of microsomal cytochrome P-448.

Aminopyrine N-Demethylase↗
PubMed1984

Monoclonal antibodies against cell surface antigens present on human urinary bladder cancer cells.

After hybridomas were prepared by cell fusion between the mouse myeloma cell line P3x63Ag8.653 and the spleen cells of a BALB/c mouse hyperimmune to the human bladder cancer KU-1 cell line, they were cloned. Monoclonal antibodies (HBA4, HBE3, HBE10, HBF2, HBG9, and HBH8) from the hybridoma clones were selected for their serologic reactivity to cell surface antigens of KU-1 cells and for their unresponsiveness to 2 human lymphoma cell lines. They were cross-reactive with a characteristic portion of human epithelial tumor cell lines and with surgically resected bladder cancer tissues. With regard to reactivity to normal human cells and tissues, HBG9 alone was reactive to epidermis and both HBF2 and HBH8 were reactive to erythrocytes, but none of the other 3 monoclonal antibodies was reactive to any normal cells or tissues. The biochemical analysis of the antigens defined at least three antigenic systems. One system was a glycopeptide complex recognized by HBA4, HBE3, and HBG9, and it consisted of molecules having molecular weights of 78,000 (major) and 40,000 and 130,000, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the 125I-radiolabeled extracts of KU-1 cells. Treatment of KU-1 cells with tunicamycin or neuraminidase lowered the reactivity to these antibodies, suggesting that the antigenic determinants reside in sialoglycoproteins. Antigenic determinants against HBG9 and the other two antibodies (HBA4 and HBE3) appeared to be different, as judged by the serologic reactivities. The other two antigenic systems detected by HBE10, HBF2, and HBH8 were defined as neutral glycolipids, according to heat stability, solubility in organic solvents, and characters in lipid fractionation. When examined by thin-layer chromatography in chloroform-methanol-0.25% KCl (30:15:4), a lipid component recognized by HBE10 migrated to a single zone [retardation factor (Rf), 0.33]. The other two antibodies (HBF2 and HBH8) did detect two lipid components (Rf, 0.23 and 0.33). Although the lipid component detected by HBE10 showed the same migration distance as one of the components detected by HBH8 (or HBF2), the antigenic determinants defined by these antibodies appeared to be different, as judged by their serologic reactivities.

Antibodies, Monoclonal↗