Tomio Takeuchi

Publications (3)4.94 Total impact

• Article: Improvement of mitomycin C‐ and cyclophosphamide‐induced thrombocytopenia and leucocytopenia by prior treatment with deoxyspergualin in dogs

  Kyuichi Nemoto, Miwa Ogino, Yumi Sugawara, Fuminori Abe, Junpei Ito, Tomio Takeuchi
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  ABSTRACT: Deoxyspergualin (DGS) is a new immunosuppressant which has shown inhibitory haemopoietic activity. We investigated the myeloprotective effect of DSG against the haemopoietic injury of mitomycin C (MMC) or cyclophosphamide (CYC) by measuring peripheral blood cell numbers in dogs. DSG given at 5 mg/kg on days 3, 2 and 1 before, or at 10 mg/kg on either days 2 and 1 before or on day 1 before and the day of injection of MMC at 0.25 mg/kg ameliorated both the thrombocytopenia and leucopenia caused by MMC. This ameliorative effect was more evident on platelet counts than on white blood cell counts. In addition, the leucopenia and thrombocytopenia induced by a single injection of CYC at 10 mg/kg was also ameliorated by prior DSG administration. These findings suggest that DSG may be useful in protecting against the haemopoietic damage induced by chemotherapeutic agents in the treatment of cancer.
  British Journal of Haematology 06/1994; 87(3):572 - 575. · 4.94 Impact Factor
• Article: Deoxyspergualin, a novel immunosuppressant, markedly inhibits human mixed lymphocyte reaction and cytotoxic T-lymphocyte activity in vitro

  Hideji Fujii, Teruyo Takada, Kyuichi Nemoto, Fuminori Abe, Akio Fujii, James E. Talmadge, Tomio Takeuchi
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  ABSTRACT: Deoxyspergualin (DSG) has demonstrated potent immunosuppressive activities in vivo. However, because of its lability in culture medium, the mechanism of activity has not yet been identified in vitro. In this study, a more stable analogue, deoxymethylspergualin (MeDSG), was used to investigate the in vitro immunosuppressive activity of DSG. MeDSG suppressed both human mixed lymphocyte reaction (MLR) and cytotoxi T-lymphocyte (CTL) activity at doses greater than 0.1 μg/ml in vitro. In kinetics studies, MeDSG was found to suppress a MLR when added on day 3 of a 7 day MLR incubation but cyclosporin A (CYA) suppressed a MLR only when added during the initial stage of a MLR (i.e. on day 1). In studies of cell surface phenotype in the MLR, MeDSG treatment decreased the numbers of CD8+ lymphocytes but those of CD4+ lymphocytes were not affected. In addition, MeDSG had no significant effect on interleukin-2 (IL-2) receptor expression or IL-2 production. These results suggest that MeDSG suppresses the T-cells which are proliferating competent cells such as cytotoxic T-cells (CD8+), but has a different mode of immunosuppressive action compared with CYA.
  International Journal of Immunopharmacology 06/1992;
• Article: Purification and characterization of a ubenimex (Bestatin)-sensitive aminopeptidase B-like enzyme from K562 human chronic myeloid leukemia cells

  Masatoshi Yamada, Yoshikazu Sukenaga, Hideji Fujii, Fuminori Abe, Tomio Takeuchi
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  ABSTRACT: A ubenimex-sensitive aminopeptidase B-like enzyme was purified from the non-membrane-bound fraction of K562 cells by a series of chromatographic procedures and slab-gel electrophoresis. The apparent molecular mass of the enzyme was estimated to be 73 kDa by SDS-PAGE. The aminopeptidase activity was activated by chloride ions and inhibited by Zn2+, Cu2+, Cd2+, and p-chloromercuribenzoic acid. Ubenimex was a potent inhibitor of this aminopeptidase in the nanomolar range. The sequence of the N-terminus of the protein was not determined. Partial amino acid sequencing revealed that the N-terminus of this aminopeptidase B-like enzyme was blocked by acylation. The partial sequences of the two fragments produced by CNBr cleavage and an acylamino acid-releasing reaction showed this enzyme to be a new aminopeptidase.
  FEBS Letters.