Katsutaro Hirota
Chiba University
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Katsutaro Hirota.
Gastroenterology | 1985
Osamu Yokosuka; Masao Omata; Fumio Imazeki; Katsutaro Hirota; Junko Mori; Katsuo Uchiumi; Yoshimi Ito; Kunio Okuda
The efficacy of adenine arabinoside (Ara-A) alone or in combination with prednisolone utilizing its withdrawal effect was studied in 43 patients with deoxyribonucleic acid polymerase- and hepatitis B e antigen-positive chronic hepatitis. Ten patients were treated with 10 mg/kg body wt of Ara-A alone for 4-8 wk. In 9 cases, prednisolone (40 mg/day) was given at a constant dosage for 4 wk before Ara-A treatment. Fourteen patients received oral prednisolone alone for 4 wk, and 10 patients served as untreated controls. Six of 9 patients (67%) undergoing the combination therapy became seronegative for hepatitis B e antigen, whereas only 4 of 24 patients (17%) treated either with Ara-A alone or prednisolone alone lost the antigen. Two of the 10 untreated patients became seronegative for hepatitis B e antigen during the same follow-up period of 9 mo. This prospective controlled study suggests that the combination of immunomodulation by steroid withdrawal and subsequent Ara-A is more effective in the treatment of patients with chronic liver disease and active hepatitis B virus replication than treatment with Ara-A alone.
Gastroenterology | 1986
Averell H. Sherker; Katsutaro Hirota; Masao Omata; Kunio Okuda
Foscarnet (trisodium phosphonoformate) is a new antiviral compound with in vitro inhibitory effects against the DNA polymerases of hepadna viruses. To study the effects of the drug in chronic hepadna virus infection, we treated ducks chronically infected with duck hepatitis B virus for 10 days with either low-dose foscarnet (50 mg/kg i.p. b.i.d.), high-dose foscarnet (250 mg/kg i.p. b.i.d.), or sterile water injections. Serum duck hepatitis B virus DNA and intrahepatic replicative forms of the virus were measured using molecular biological techniques with both a double-stranded radiolabeled DNA probe and a plus-strand (noncoding) specific RNA probe. We found a dose-related decrease in serum and intrahepatic duck hepatitis B virus DNA during treatment, with a rapid return toward baseline values after the cessation of treatment. There was a disproportionate decrease in the plus strand of viral DNA with treatment. We conclude that foscarnet exerts its effect in hepadna virus infection through inhibition of viral DNA polymerase. Further study is necessary to determine whether foscarnet, by itself or in combination with other treatment modalities, has a role to play in the treatment of chronic hepatitis B infections in humans.
Journal of Hepatology | 2000
Yasushi Shiratori; Alan S. Perelson; Leor S. Weinberger; Fumio Imazeki; Osamu Yokosuka; Ryo Nakata; Masashi Ihori; Katsutaro Hirota; Naomi Ono; Hisamoto Kuroda; Teiji Motojima; Masaru Nishigaki; Masao Omata
BACKGROUND/AIM Since patients with high viral load and HCV subtype 1b are known to respond poorly to interferon (IFN) therapy, the viral dynamics of HCV RNA after initiation of interferon therapy were examined in the present study with respect to two different administration regimens, once vs. twice a day. METHODS Twenty-two patients with chronic hepatitis C confirmed by liver biopsy and with >1 Meq/ml of HCV RNA and HCV subtype 1b were randomly assigned to two different IFN administration regimens (6 million units of IFN once a day or 3 million units of IFN twice a day), and the serum HCV RNA level was serially measured. RESULTS Graphs of HCV RNA levels vs. treatment time showed an initial rapid fall, followed by a slower clearance phase. Fitting the data to a model for HCV decay proposed by Neumann et al. showed that the treatment efficacy was significantly higher with twice daily administration. Negativity for HCV RNA measured by Amplicor assay in the twice-a-day administration group was 18%, 73% and >89% at 1, 2 and 3 weeks, respectively, in contrast to 0%, 0%, and 18%, respectively, with once-a-day administration. However, a significant reduction of platelet count and albumin level, a marked increase in serum aspartate aminotransferase/alanine aminotransferase, and a high incidence of renal toxicity (proteinuria) were found in patients receiving IFN twice a day in comparison with those receiving it once a day. CONCLUSION The twice-a-day administration of IFN accelerated the clearance of HCV RNA from serum, leading to a more efficient virological response for patients with chronic hepatitis C, but with a high rate of renal toxicity.
Kanzo | 1985
Yoshimi Ito; Junko Mori; Masao Omata; Katsuo Uchiumi; Osamu Yokosuka; Fumio Imazeki; Yasuhisa Matsuyama; Katsutaro Hirota; Masako Tanaka; Masami Tagawa; Kunio Okuda
HBs抗原陽性者140名中に発見されたδ抗原陽性2名のうち1例に酵素抗体法にて免疫電顕的検索を行った.δ抗原は肝細胞核内にのみ染色され,核小体を除く核内に比較的び漫性に見い出されるが核によって染色性の強弱は様々であり,その頻度は45個につき陽性核は1個(2.2%)であった.強拡大では雲状の個々の形態不鮮明なものが主であるが,1部に直径10~20nmの境界不鮮明な顆粒状のものが見られるが明確な形態は認められなかった.細胞質では染色されているものはなかった.各阻止試験組み合せの免疫電顕的検索で,核内に陽性に染色されるものはδ抗原であることを確認した.本邦におけるδ抗原についての免疫電顕的検索は最初である.
Annals of Internal Medicine | 2005
Yasushi Shiratori; Y. Ito; Osamu Yokosuka; Fumio Imazeki; Ryo Nakata; Naohide Tanaka; Yasuyuki Arakawa; Etsuko Hashimoto; Katsutaro Hirota; Haruhiko Yoshida; Yasuo Ohashi; Masao Omata
Hepatology | 1994
Susumu Takano; Yoshimi Ito; Osamu Yokosuka; Masao Ohto; Katsuo Uchiumi; Katsutaro Hirota; Masao Omata
Biochemical and Biophysical Research Communications | 1996
Osamu Kawamata; Haruhiko Yoshida; Katsutaro Hirota; Akira Yoshida; Ryuji Kawaguchi; Yasushi Shiratori; Masao Omata
Gastroenterology | 1985
Osamu Yokosuka; Masao Omata; Fumio Imazeki; Katsutaro Hirota; Junko Mori; Katsuo Uchiumi; Yoshimi Ito; Kunio Okuda
Journal of Clinical Microbiology | 1998
Haruhiko Yoshida; Katsutaro Hirota; Yasushi Shiratori; Takeshi Nihei; Shin Amano; Akira Yoshida; Osamu Kawamata; Masao Omata
Hepatology | 1987
Katsutaro Hirota; Averell H. Sherker; Masao Omata; Osamu Yokosuka; Kunio Okuda