Kumamoto University

About: Kumamoto University is a education organization based out in Kumamoto, Kumamoto, Japan. It is known for research contribution in the topics: Cancer & Population. The organization has 19602 authors who have published 35513 publications receiving 901260 citations. The organization is also known as: Kumamoto Daigaku.

Dependence on O2- generation by xanthine oxidase of pathogenesis of influenza virus infection in mice.

Abstract: We evaluated various biochemical parameters in influenza virus-infected mice and focused on adenosine catabolism in the supernatant of bronchoalveolar lavage fluid (s-BALF), lung tissue, and serum (plasma). The activities of adenosine deaminase (ADA) and xanthine oxidase (XO), which generates O2-, were elevated in the s-BALF, lung tissue homogenate, and serum (plasma). The elevations were most remarkable in s-BALF and in lung tissue: We found a 170-fold increase in ADA activity and a 400-fold increase in XO activity as measured per volume of alveolar lavage fluid. The ratio of activity of XO to activity of xanthine dehydrogenase in s-BALF increased from 0.15 +/- 0.05 (control; no infection) to 1.06 +/- 0.13 on day 6 after viral infection. Increased levels of various adenosine catabolites (i.e., inosine, hypoxanthine, xanthine, and uric acid) in serum and s-BALF were confirmed. We also identified O2- generation from XO in s-BALF obtained on days 6 and 8 after infection, and the generation of O2- was enhanced remarkably in the presence of adenosine. Lastly, treatment with allopurinol (an inhibitor of XO) and with chemically modified superoxide dismutase (a scavenger of O2-) improved the survival rate of influenza virus-infected mice. These results indicate that generation of oxygen-free radicals by XO, coupled with catabolic supply of hypoxanthine from adenosine catabolism, is a pathogenic principle in influenza virus infection in mice and that a therapeutic approach by elimination of oxygen radicals thus seems possible.

Genetic and epigenetic inactivation of tax gene in adult T‐cell leukemia cells

Abstract: To clarify the status of tax gene, we analyzed human T-cell leukemia virus type-I (HTLV-I) associated cell lines and fresh adult T-cell leukemia (ATL) cells. We compared 2 types of HTLV-I associated cell lines: one was derived from leukemic cells (leukemic cell line) and the other from nonleukemic cells (nonleukemic cell line). Although all nonleukemic cell lines expressed Tax, it could not be detected in 3 of 5 leukemic cell lines, in which nonsense mutation or deletion (60 bp) of tax genes, and DNA methylation in 5'-LTR were identified as the responsible changes. We found such genetic changes of the tax gene in 5 of 47 fresh ATL cases (11%). The tax gene transcripts could be detected in 14 of 41 fresh ATL cases (34%) by RT-PCR. In ATL cases with genetic changes that could not produce Tax protein, the tax gene was frequently transcribed, suggesting that such cells do not need the transcriptional silencing. Although DNA methylation of 5'-LTR was detected in the fresh ATL cases (19 of 28 cases; 68%), the complete methylation associated with transcriptional silencing was observed only in 4 cases. Since partial methylation could not silence the transcription, and the tax gene transcription was not detected in 27 of 41 cases (66%), the epigenetic change(s) other than DNA methylation is considered to play an important role in the silencing.