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Dive into the research topics where Tomoyuki Kuramitsu is active.

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Featured researches published by Tomoyuki Kuramitsu.


Hepatology | 2006

Influence of genotypes and precore mutations on fulminant or chronic outcome of acute hepatitis B virus infection.

Atsushi Ozasa; Yasuhito Tanaka; Etsuro Orito; Masaya Sugiyama; Jong-Hon Kang; Shuhei Hige; Tomoyuki Kuramitsu; Kazuyuki Suzuki; Eiji Tanaka; Shunichi Okada; Hajime Tokita; Yasuhiro Asahina; Kazuaki Inoue; Shinichi Kakumu; Takeshi Okanoue; Yoshikazu Murawaki; Keisuke Hino; Morikazu Onji; Hiroshi Yatsuhashi; Hiroshi Sakugawa; Yuzo Miyakawa; Ryuzo Ueda; Masashi Mizokami

The outcome of acute hepatitis B virus (HBV) infection is variable, influenced by host and viral factors. From 1982 through 2004, 301 patients with acute HBV infection entered a multi‐center cross‐sectional study in Japan. Patients with fulminant hepatitis (n = 40) were older (44.7 ± 16.3 vs. 36.0 ± 14.3 years, P < .0017), less predominantly male (43% vs. 71%, P = .0005), less positive for hepatitis B e antigen (HBeAg) (23% vs. 60%, P < .0001), less infected with subgenotype Ae (0% vs. 13%, P < .05), and more frequently with Bj (30% vs. 4%, P < .0001) than those with acute self‐limited hepatitis (n = 261). Precore (G1896A) and core‐promoter (A1762T/G1764A) mutations were more frequent in patients with fulminant than acute self‐limited hepatitis (53% vs. 9% and 50% vs. 17%, P < .0001 for both). HBV infection persisted in only three (1%) patients, and they represented 2 of the 23 infected with Ae and 1 of the 187 with the other subgenotypes (9% vs. 0.5%, P = .032); none of them received antiviral therapy. In multivariate analysis, age 34 years or older, Bj, HBeAg‐negative, total bilirubin 10.0 mg/dL or greater, and G1896A mutation were independently associated with the fulminant outcome. In in vitro transfection experiments, the replication of Bj clone was markedly enhanced by introducing either G1896A or A1762T/G1764A mutation. In conclusion, persistence of HBV was rare (1%) and associated with Ae, whereas fulminant hepatitis was frequent (13%) and associated with Bj and lack of HBeAg as well as high replication due to precore mutation in patients with acute HBV infection. (HEPATOLOGY 2006;44:326–334.)


Journal of Clinical Microbiology | 2009

Distribution of Hepatitis B Virus Genotypes among Patients with Chronic Infection in Japan Shifting toward an Increase of Genotype A

Kentaro Matsuura; Yasuhito Tanaka; Shuhei Hige; Gotaro Yamada; Yoshikazu Murawaki; Masafumi Komatsu; Tomoyuki Kuramitsu; Sumio Kawata; Eiji Tanaka; Namiki Izumi; Chiaki Okuse; Shinichi Kakumu; Takeshi Okanoue; Keisuke Hino; Yoichi Hiasa; Michio Sata; Tatsuji Maeshiro; Fuminaka Sugauchi; Shunsuke Nojiri; Takashi Joh; Yuzo Miyakawa; Masashi Mizokami

ABSTRACT Acute hepatitis B virus (HBV) infection has been increasing through promiscuous sexual contacts, and HBV genotype A (HBV/A) is frequent in patients with acute hepatitis B (AHB) in Japan. To compare the geographic distribution of HBV genotypes in patients with chronic hepatitis B (CHB) in Japan between 2005 and 2006 and between 2000 and 2001, with special attention to changes in the proportion of HBV/A, a cohort study was performed to survey changes in genotypes of CHB patients at 16 hospitals throughout Japan. Furthermore, we investigated the clinical characteristics of each genotype and examined the genomic characteristics of HBV/A isolates by molecular evolutionary analyses. Of the 1,271 patients, 3.5%, 14.1%, and 82.3% were infected with HBV/A, -B, and -C, respectively. In comparison with our previous survey during 2000 and 2001, HBV/A was twice as frequent (3.5% versus 1.7%; P = 0.02). The mean age was lower in the patients with HBV/A than in those with HBV/B or -C. Based on phylogenetic analyses of 11 full-length genomes and 29 pre-S2/S region sequences from patients, HBV/A isolates were imported from Europe and the United States, as well as the Philippines and India. They clustered with HBV/A from AHB patients and have spread throughout Japan. HBV/A has been increasing in CHB patients in Japan as a consequence of AHB spreading in the younger generation through promiscuous sexual contacts, aided by a tendency of HBV/A to induce chronic hepatitis. The spread of HBV/A infection in Japan should be prevented by universal vaccination programs.


Journal of Gastroenterology | 1996

Fulminant hepatitis caused by hepatitis C virus during treatment for multiple sclerosis

Masato Funaoka; Kazumaro Kato; Masafumi Komatsu; Tsuyoshi Ono; Takao Hoshino; Junji Kato; Tomoyuki Kuramitsu; Tohru Ishii; Itaru Toyoshima; Osamu Masamune

A 55-year-old woman was treated at our hospital for multiple sclerosis. Therapy consisted of glucocorticosteroids and cyclosporin. In the 7th week after these drugs were discontinued the patient developed acute liver failure due to fulminant hepatitis (FH) and died. Post-mortem examination showed massive liver necrosis. Serologic examination was negative for hepatitis B virus-related markers. Anti-hepatitis C virus (anti-HCV) antibody and serum HCV RNA were negative on admission, but HCV RNA appeared concurrently with the onset of FH. Although HCV infection rarely causes FH, it was considered to be the cause of FH in this patient, since there were no other causes of acute liver injury. We suspect that underlying immunologic abnormalities in conjunction with HCV infection may have precipitated the FH.


Journal of Gastroenterology and Hepatology | 1999

Tauroursodeoxycholic acid enhances phagocytosis of the cultured rat Kupffer cell

Masato Funaoka; Masafumi Komatsu; Itaru Toyoshima; Ken-ichiro Mikami; Tsuyoshi Ono; Takao Hoshino; Junji Kato; Tomoyuki Kuramitsu; Tohru Ishii; Osamu Masamune

Background: Ursodeoxycholic acid is used in the treatment of acute and chronic intrahepatic cholestasis because it ameliorates cholestasis and protects hepatocytes. However, few studies have examined the effect of bile acids on the function of Kupffer cells.


Canadian Journal of Gastroenterology & Hepatology | 1997

Pilot Study of Ofloxacin and Interferon-Alpha Combination Therapy for Chronic Hepatitis C without Sustained Response to Initial Interferon Therapy

Masafumi Komatsu; Tohru Ishii; Tsuyoshi Ono; Takao Hoshino; Tomoyuki Kuramitsu; Takashi Goto; Tomoo Fujii; Itaru Toyoshima; Mitsuro Chiba; Osamu Masamune

A controlled trial comparing combination therapy with ofloxacin (OFLX) and interferon (IFN) versus IFN monotherapy was conducted in patients with chronic hepatitis C who failed IFN therapy. Twenty patients were assigned randomly to two groups. Equal doses of recombinant IFN alpha-2b were administered to each group for 24 weeks. For the IFN plus OFLX group, OFLX was administered for 12 weeks at a daily dose of 600 mg. Levels of hepatitis C virus RNA declined significantly from the first month after the start of IFN treatment compared with those before administration in both groups. Serum alanine aminotransferase levels were significantly lower in the IFN plus OFLX group at two and six months after the start of treatment than levels in the IFN group. The fraction of subjects whose levels of serum ALT normalized was also higher in the IFN plus OFLX group. Larger clinical trials should be undertaken.


Hepatology Research | 2011

Recommendation of lamivudine-to-entecavir switching treatment in chronic hepatitis B responders: Randomized controlled trial

Kentaro Matsuura; Yasuhito Tanaka; Atsunori Kusakabe; Shuhei Hige; Jun Inoue; Masashi Komatsu; Tomoyuki Kuramitsu; Katsuharu Hirano; Tomoyoshi Ohno; Izumi Hasegawa; Haruhiko Kobashi; Keisuke Hino; Yoichi Hiasa; Hideyuki Nomura; Fuminaka Sugauchi; Shunsuke Nojiri; Takashi Joh; Masashi Mizokami

Aim:  In the 2007–2008 guidelines of the study group (Ministry of Health, Labor and Welfare of Japan), lamivudine (LAM)‐continuous treatment was recommended in patients treated with LAM for more than 3 years who maintained hepatitis B virus (HBV) DNA less than 2.6 log copies/mL, because in these patients LAM resistance might exist and switching treatment to entecavir (ETV) might cause ETV resistance. However, there was no evidence on whether switching treatment to ETV‐ or LAM‐continuous treatment was better in those patients. In the present study, we performed a randomized controlled trial of LAM‐to‐ETV switching treatment.


Hepatology Research | 1997

A dose-dependent controlled trial of human lymphoblastoid interferon α for genotype 1b chronic hepatitis C associated with high HCV-RNA levels

Masafumi Komatsu; Tohru Ishii; Tsuyoshi Ono; Tomoyuki Kuramitsu; Takao Hoshino; Osamu Masamune; Tsukasa Yoshida; Hitoshi Yagisawa; Nobuo Yamada

Abstract The efficacy of Interferon (IFN) therapy against hepatitis C is greatly affected by viral factors such as the level of viremia and the HCV genotype. The prognosis of those with high serum HCV-RNA levels in genotype 1b is poor. In the present report, we carried out a randomized controlled study of two IFN doses for patients with genotype 1b chronic hepatitis C whose serum HCV-RNA levels were at least 10 6 copies/ml as determined by multicyclic polymerase chain reaction (PCR) assay. These patients were randomly divided into two groups. Group A received 6 million units (MIU) of IFN 6 days per week for 8 weeks, followed by the same dose 3 days per week for 16 weeks (total IFN dose: 576 MIU). Group B received 6 MIU of IFN 6 days per week for 2 weeks, followed by the same dose 3 days per week for 22 weeks (total IFN dose: 480 MIU). The number of complete responders was four of 24 (16.6%) in group A and three of 20 (15.0%) in group B. There was no significant difference between the groups. On the basis of these findings, it appears that there is no advantage in lengthening the initial period of consecutive IFN administration to 8 weeks or in increasing the total dose by 100 MIU for those with genotype 1b hepatitis C and high virus levels.


Gastroenterologia Japonica | 1992

Isolation of kinesin from rat liver.

Masafumi Komatsu; Ko Nakajima; Mitsuo Goto; Tomoyuki Kuramitsu; Shin-ichi Ishida; Tsuyosi Ono; Itaru Toyosima; Osamu Masamune

Kinesin is a translocator protein which mediates microtubule-based transport of organelle and vesicles. Microtubules support major roles in some intracellular transport systems in a variety of cells. However, it is not known which proteins comprise the translocator in the liver 9 In this study, we determined the molecular weight and motility of hepatic kinesin. The translocator protein fraction, isolated from rat liver by a modification of Vales method, consisted of many kind of protein species as identified by SDS-PAGE. The most prominent of these was a ll6kDa protein. The ll6kDa polypeptide had property of forming a high affinity complex with microtubules in the presence of nonhydrolyzable ATP analog, adenylyl imidodiphosphate(AMP-PNP). The ll6kDa polypeptide released from the microtubules with ATP reacts with monoclonal antibodies to sea urchin and chicken brain kinesin heavy chain (Fig.A,B). Gliding of reconstituted microtubules in the presence of ATP on the ll6kDa polypeptide treated with glass plate was visualized with DIC-video enhanced A B microscopy. The mean i ~ 3 ~ 5 6 7 s i 2 3 4 5 6 7 s v oywa0000 1 IIi o u I,, 9 116K-.,QKHC 116-97.~indicated that the ,~_ ~ == ll6kDa polypeptide ,s~,r~ 4~from rat liver was ~ __~i__ kinesin heavy chain. Figure: Electrophoretic and immunoblotting pattern obtained in the of the preparation of kinesin from rat liver extract. A: SDA-PAGE with silver staining. B: Immunoblotting using sea urchin kinesin mAb. Lanel: Supernatant after 150000xg centrifugation. 2: Microtubule containing pellet. 3: Supernatant after wash in buffer containing ATP. 4: Pellet after ATP extraction. 5: Supernatant after wash in buffer containing GTP. 6: Pellet after GTP extraction 9 7: Supernatant after wash in buffer containing ATP and AMP-PNP. 8: Pellet after ATP and AMP-PNP extraction.


Journal of Hepatology | 1995

Purification and characterization of cytoplasmic dynein of rabbit liver

Ko Nakajima; Masafumi Komatsu; Itaru Toyoshima; Tomoyuki Kuramitsu; Tsuyoshi Ono; Masato Funaoka; Junji Kato; Osamu Masamune

Cytoplasmic dynein is a microtubule-dependent motor protein, which plays a role in intracellular transport. However, there have been few studies regarding the role of cytoplasmic dynein in the liver. Purification of cytoplasmic dynein from rabbit liver took advantage of the affinity of microtubule-dependent motor proteins for microtubules. Purified dynein contained heavy chain (450 kDa), intermediate chain (75 kDa), light chains (45-58 kDa) and dynactin (150 kDa). The subunit composition was consistent with previously reported data on brain cytoplasmic dynein. Microtubules prepared from bovine brain were driven by purified cytoplasmic dynein from rabbit liver, and movements of microtubules were visualized by video-enhanced differential interference contrast microscopy. The mean velocity of the motile microtubules was 1.09 +/- 0.13 microns/s. Our study provides evidence of rapid intracellular transport in hepatocytes controlled by cytoplasmic dynein.


Canadian Journal of Gastroenterology & Hepatology | 1999

GB Virus C Infection: Clinical Significance

Xiang Wei Meng; Masafumi Komatsu; Shigetoshi Ohshima; Kunio Nakane; Tomoo Fujii; Takashi Goto; Kazuo Yoneyama; Tomoyuki Kuramitsu; Motokazu Mukaide

GB virus C (GBV-C) RNA positivity rates were examined in serum specimens from 231 patients with liver disease (23 patients with hepatitis B, 175 patients with hepatitis C, five patients with hepatitis B virus plus hepatitis C virus coinfection, and 28 patients with non-A, non-B, non-C hepatitis) to clarify the clinical significance of this virus. GBV-C RNA was detected in none of 12 patients with fulminant hepatitis, one of two patients with acute hepatitis positive for hepatitis B surface antigen and one of four patients with acute non-A, non-B, non-C hepatitis. Pathogenetic involvement of GBV-C was suspected in some patients in the latter group. Among patients with the non-B, non-C type of chronic disease, one of seven with cirrhosis (14%) and none with chronic hepatitis or hepatocellular carcinoma were GBV-C-positive. In chronic hepatitis C patients who had received interferon treatment, no difference was found in clinical findings, alanine aminotransferase (ALT) concentrations, histology or response to interferon between 11 patients who were GBV-C RNA-positive and 101 patients who were GBV-C RNA-negative. Moreover, changes in ALT after interferon therapy showed no relation to positivity for GBV-C RNA. On the basis of these findings, GBV-C appears to be an unlikely cause of initiation or progression of chronic hepatic diseases.

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