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Articles by A Takeuchi
Total Records ( 2 ) for A Takeuchi
  Y Kamiryo , M Eto , H Yamada , T Yajima , M Harano , A Takeuchi , K Tatsugami , M Hamaguchi , S Naito and Y. Yoshikai
 

Nonmyeloablative allogeneic stem cell transplantation (SCT) has been used for various malignancies, although detailed mechanisms of antitumor effects remain unclear. We showed that a nonmyeloablative allogeneic SCT regimen, which consists of mixed chimerism induced by an injection of donor spleen and bone marrow cells followed by cyclophosphamide treatment and a donor lymphocyte infusion (DLI), exerted antitumor effects on established murine bladder tumor, MBT-2. An expansion of donor CD4 T cells accompanied by transient but vigorous IFN- production was detected shortly after DLI. In vivo neutralization of IFN- or depletion of CD4 T cells from DLI abolished the antitumor effects, indicating an indispensable role of donor CD4 T cells producing IFN-. Donor as well as host CD8 T cells accumulated in the tumor region with time. Importantly, depletion of CD8 T cells from DLI did not reverse the suppression of tumor growth, indicating that CD4 T cells play a more essential role in mediating early antitumor effects. Furthermore, tumor-specific response of host CD8 T cells was suggested. These results not only provide the first evidence of nonmyeloablative allogeneic SCT for the treatment of bladder tumor but also elucidate detailed mechanisms of antitumor effects provoked by DLI. [Cancer Res 2009;69(12):5151–8]

  Y Takaoka , M Ohta , A Takeuchi , K Miura , M Matsuo , T Sakaeda , A Sugano and H. Nishio
 

UDP-glucuronosyltransferase 1A1 (UGT1A1) is an endoplasmic reticulum membrane protein that catalyses glucuronidation. Mutant UGT1A1 possesses a different conjugation capacity, and the molecular mechanisms regulating these conjugation reactions are as yet unclear. To elucidate these molecular mechanisms, we simulated and analysed the glucuronidation of wild-type UGT1A1 and six UGT1A1 mutants, with bilirubin as the substrate. We found that only the orientation of the substrates correlated with the conjugation capacity in in vitro experiments. Inasmuch as glucuronidation is an intermolecular rearrangement reaction, we find that the conjugation reaction proceeds only when the hydroxyl group of the substrate is oriented towards the coenzyme, which allows the proton transfer to occur.

 
 
 
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