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Dive into the research topics where Kotaro Matsunaga is active.

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Featured researches published by Kotaro Matsunaga.


Hepatology Research | 2010

A predictive model of response to peginterferon ribavirin in chronic hepatitis C using classification and regression tree analysis.

Masayuki Kurosaki; Kotaro Matsunaga; Itsuko Hirayama; Tomohiro Tanaka; Mitsuaki Sato; Yutaka Yasui; Nobuharu Tamaki; Takanori Hosokawa; Ken Ueda; Kaoru Tsuchiya; H. Nakanishi; Hiroki Ikeda; Jun Itakura; Yuka Takahashi; Yasuhiro Asahina; Megumu Higaki; Nobuyuki Enomoto; Namiki Izumi

Aim:  Early disappearance of serum hepatitis C virus (HCV) RNA is the prerequisite for achieving sustained virological response (SVR) in peg‐interferon (PEG‐IFN) plus ribavirin (RBV) therapy for chronic hepatitis C. This study aimed to develop a decision tree model for the pre‐treatment prediction of response.


Hepatology Research | 2010

Hepatic steatosis in chronic hepatitis C is a significant risk factor for developing hepatocellular carcinoma independent of age, sex, obesity, fibrosis stage and response to interferon therapy

Masayuki Kurosaki; Takanori Hosokawa; Kotaro Matsunaga; Itsuko Hirayama; Tomohiro Tanaka; Mitsuaki Sato; Yutaka Yasui; Nobuharu Tamaki; Ken Ueda; Kaoru Tsuchiya; Teiji Kuzuya; H. Nakanishi; June Itakura; Yuka Takahashi; Yasuhiro Asahina; Nobuyuki Enomoto; Namiki Izumi

Aim:  Hepatic steatosis is linked to development of hepatocellular carcinoma (HCC) in non‐viral liver disease such as non‐alcoholic steatohepatitis. The present study aimed to assess whether hepatic steatosis is associated with the development of HCC in chronic hepatitis C.


Journal of Gastroenterology and Hepatology | 2014

Stereotactic ablative body radiotherapy for previously untreated solitary hepatocellular carcinoma

Atsuya Takeda; Naoko Sanuki; Takahisa Eriguchi; Takashi Kobayashi; Shogo Iwabutchi; Kotaro Matsunaga; Tomikazu Mizuno; Kae Yashiro; Shuichi Nisimura; Etsuo Kunieda

Stereotactic ablative body radiotherapy (SABR) is a relatively new treatment for hepatocellular carcinoma (HCC). The outcomes of SABR for previously untreated solitary HCC unfit for ablation and surgical resection were evaluated.


Journal of Hepatology | 2008

The presence of steatosis and elevation of alanine aminotransferase levels are associated with fibrosis progression in chronic hepatitis C with non-response to interferon therapy

Masayuki Kurosaki; Kotaro Matsunaga; Itsuko Hirayama; Tomohiro Tanaka; Mitsuaki Sato; Nobutoshi Komatsu; Naoki Umeda; Takanori Hosokawa; Ken Ueda; Kaoru Tsuchiya; H. Nakanishi; Jun Itakura; Yasuhiro Asahina; Shozo Miyake; Nobuyuki Enomoto; Namiki Izumi

BACKGROUND/AIMS Interferon (IFN) therapy leads to regression of hepatic fibrosis in chronic hepatitis C patients who achieve a sustained virologic response (SVR), while the beneficial effect is limited in those who fail to do so. The aim of the present study was to define factors associated with progression of fibrosis in patients who do not achieve a SVR. METHODS Fibrosis staging scores were compared between paired liver biopsies before and after IFN in 97 chronic hepatitis C patients who failed therapy. The mean interval between biopsies was 5.9 years. Factors associated with progression of fibrosis were analyzed. RESULTS Fibrosis progressed in 23%, remained unchanged in 47% and regressed in 29%. Steatosis and a high average alanine aminotransferase (ALT) between biopsies were independent factors for progression of fibrosis with risk ratios of 5.53 and 4.48, respectively. Incidence and yearly rate of progression of fibrosis was 64% and 0.22+/-0.29 fibrosis units per year in those with both risk factors compared to 8% and -0.04+/-0.17 fibrosis units per year in those negative for both factors. CONCLUSIONS Hepatic steatosis and elevated ALT levels are risk factors for progression of fibrosis in chronic hepatitis C patients who fail to achieve a SVR to IFN therapy and therefore may be therapeutic targets to halt the potentially progressive disease.


Cancer | 2016

Phase 2 study of stereotactic body radiotherapy and optional transarterial chemoembolization for solitary hepatocellular carcinoma not amenable to resection and radiofrequency ablation.

Atsuya Takeda; Naoko Sanuki; Yuichiro Tsurugai; Shogo Iwabuchi; Kotaro Matsunaga; Hirotoshi Ebinuma; Kento Imajo; Yousuke Aoki; Hidetsugu Saito; Etsuo Kunieda

Curative treatment options for patients with early stage hepatocellular carcinoma (HCC) include resection, liver transplantation, and percutaneous ablation therapy. However, even patients with solitary HCC are not always amenable to these treatments. The authors prospectively investigated the clinical outcomes of patients who received stereotactic body radiotherapy (SBRT) for solitary HCC.


Hepatology Research | 2014

Prospective comparison of real‐time tissue elastography and serum fibrosis markers for the estimation of liver fibrosis in chronic hepatitis C patients

Nobuharu Tamaki; Masayuki Kurosaki; Shuya Matsuda; Toru Nakata; Masaru Muraoka; Yuichiro Suzuki; Yutaka Yasui; Shoko Suzuki; Takanori Hosokawa; Takashi Nishimura; Ken Ueda; Kaoru Tsuchiya; H. Nakanishi; Jun Itakura; Yuka Takahashi; Kotaro Matsunaga; Kazuhiro Taki; Yasuhiro Asahina; Namiki Izumi

Real‐time tissue elastography (RTE) is a non‐invasive method for the measurement of tissue elasticity using ultrasonography. Liver fibrosis (LF) index is a quantitative method for evaluation of liver fibrosis calculated by RTE image features. This study aimed to investigate the significance of LF index for predicting liver fibrosis in chronic hepatitis C patients.


Journal of Gastroenterology | 2012

Pathophysiological analysis of nonalcoholic fatty liver disease by evaluation of fatty liver changes and blood flow using xenon computed tomography: can early-stage nonalcoholic steatohepatitis be distinguished from simple steatosis?

Ryuta Shigefuku; Hideaki Takahashi; Minoru Kobayashi; Hiroki Ikeda; Kotaro Matsunaga; Chiaki Okuse; Nobuyuki Matsumoto; Shiro Maeyama; Shigeru Sase; Michihiro Suzuki; Fumio Itoh

IntroductionEffective noninvasive tests that can distinguish early-stage nonalcoholic steatohepatitis (NASH) from simple steatosis (SS) have long been sought. Our aim was to determine the possibility of noninvasively distinguishing early-stage NASH from SS.Materials and methodsWe used Fick’s principle and the Kety–Schmidt equation to determine the hepatic tissue blood flow (TBF) in 65 NASH patients who underwent xenon computed tomography (Xe-CT). We calculated the lambda value (LV), i.e., Xe gas solubility coefficient, in liver and blood. We assessed the histological severity of fatty changes and fibrosis on the basis of Brunt’s classification. Liver biopsy revealed SS in 9 patients and NASH in 56 patients. NASH stages 1 and 2 were classified as early-stage NASH (Ea-NASH; 38 patients) and stages 3 and 4 as advanced-stage NASH (Ad-NASH; 18 patients). We evaluated the differences in LV and TBF among the 3 groups.ResultsLV was significantly lower in the Ad-NASH group than in the SS and Ea-NASH groups. Portal venous TBF (PVTBF) was significantly lower in the Ea-NASH group than in the SS group, and PVTBF was lower in the Ad-NASH group than in the Ea-NASH group. Total hepatic TBF (THTBF) was significantly different between the SS and Ea-NASH groups and between the SS and Ad-NASH groups.ConclusionsIn conclusion, measurements of TBF and LV are useful for evaluating the pathophysiological progression of NASH. In addition, these measurements can facilitate the differential diagnosis of SS and Ea-NASH, which may not be distinguishable by other means.


Hepatology Research | 2015

Field practice study of half-dose sorafenib treatment on safety and efficacy for hepatocellular carcinoma: A propensity score analysis

Manabu Morimoto; Kazushi Numata; Masaaki Kondo; Satoshi Kobayashi; Shinichi Ohkawa; Hisashi Hidaka; Takahide Nakazawa; Yusuke Okuwaki; Chiaki Okuse; Kotaro Matsunaga; Michihiro Suzuki; Satoshi Morita; Masataka Taguri; Katsuaki Tanaka

Patients with hepatocellular carcinoma (HCC) who receive an initial full dose of sorafenib (800 mg/day) often require a decreased dose (400 mg/day) or discontinuation of therapy because of severe adverse events. We conducted a retrospective analysis of patients with HCC to compare the safety and efficacy of full‐ to half‐dose sorafenib.


Journal of Medical Virology | 2017

Impact of resistance-associated variant dominancy on treatment in patients with HCV genotype 1b receiving daclatasvir/asunaprevir.

Hiroki Ikeda; Tsunamasa Watanabe; Chiaki Okuse; Nobuyuki Matsumoto; Toshiya Ishii; Norie Yamada; Ryuta Shigefuku; Nobuhiro Hattori; Kotaro Matsunaga; Hiroyasu Nakano; Tetsuya Hiraishi; Minoru Kobayashi; Kiyomi Yasuda; Hiroyuki Yamamoto; Hiroshi Yasuda; Masayuki Kurosaki; Namiki Izumi; Hiroshi Yotsuyanagi; Michihiro Suzuki; Fumio Itoh

Sustained virological responses (SVR) by daclatasvir (DCV) and asunaprevir (ASV) therapy for genotype 1b hepatitis C virus (HCV) infected patients has been significantly affected by pre‐existence of Y93 H resistance‐associated variants (RAVs) in the non‐structural protein 5A (NS5A) region. The aim of this study was to elucidate the dominancy of naturally occurring RAVs in viral quasispecies on treatment outcomes in patients with HCV. In total, 138 patients were prospectively selected from 152 patients treated with DCV and ASV, where evaluation of treatment outcomes at 12 weeks post‐treatment was possible. Pre‐treatment RAVs in the non‐structural protein 3 and NS5A regions were detected by polymerase chain reaction (PCR)‐Invader assays, and the ratio of Y93H RAVs in viral quasispecies was measured by quantitative PCR‐Invader assay. Among 25 patients detected the Y93H RAV, the Y93H ratio was 1–25% in 5 patients, 26–75% in 7 patients, and ≥76% in 13 patients. Overall, SVR at 12 weeks after the completion of treatment (SVR12) was 91% (125/138), and those with Y93H ratios of <1%, 1–25%, 26–75%, and ≥76% were 99%, 100%, 71%, and 23%, respectively. Thus, the SVR12 decreased as the HCV Y93H ratio increased (P < 0.0001). The dominancy of pre‐treatment RAVs of DCV and ASV affected its treatment outcomes, suggesting that evaluating the dominancy of HCV RAVs could be required for every other direct‐acting antiviral agent treatments. J. Med. Virol. 89:99–105, 2017.


International Journal of Molecular Sciences | 2016

Correlations of Hepatic Hemodynamics, Liver Function, and Fibrosis Markers in Nonalcoholic Fatty Liver Disease: Comparison with Chronic Hepatitis Related to Hepatitis C Virus

Ryuta Shigefuku; Hideaki Takahashi; Hiroyasu Nakano; Tsunamasa Watanabe; Kotaro Matsunaga; Nobuyuki Matsumoto; Masaki Kato; Ryo Morita; Yousuke Michikawa; Tomohiro Tamura; Tetsuya Hiraishi; Nobuhiro Hattori; Yohei Noguchi; Kazunari Nakahara; Hiroki Ikeda; Toshiya Ishii; Chiaki Okuse; Shigeru Sase; Fumio Itoh; Michihiro Suzuki

The progression of chronic liver disease differs by etiology. The aim of this study was to elucidate the difference in disease progression between chronic hepatitis C (CHC) and nonalcoholic fatty liver disease (NAFLD) by means of fibrosis markers, liver function, and hepatic tissue blood flow (TBF). Xenon computed tomography (Xe-CT) was performed in 139 patients with NAFLD and 152 patients with CHC (including liver cirrhosis (LC)). The cutoff values for fibrosis markers were compared between NAFLD and CHC, and correlations between hepatic TBF and liver function tests were examined at each fibrosis stage. The cutoff values for detection of the advanced fibrosis stage were lower in NAFLD than in CHC. Although portal venous TBF (PVTBF) correlated with liver function tests, PVTBF in initial LC caused by nonalcoholic steatohepatitis (NASH-LC) was significantly lower than that in hepatitis C virus (C-LC) (p = 0.014). Conversely, the liver function tests in NASH-LC were higher than those in C-LC (p < 0.05). It is important to recognize the difference between NAFLD and CHC. We concluded that changes in hepatic blood flow occurred during the earliest stage of hepatic fibrosis in patients with NAFLD; therefore, patients with NAFLD need to be followed carefully.

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Chiaki Okuse

St. Marianna University School of Medicine

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Hiroki Ikeda

Kansai Medical University

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Nobuyuki Matsumoto

St. Marianna University School of Medicine

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Michihiro Suzuki

St. Marianna University School of Medicine

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Fumio Itoh

St. Marianna University School of Medicine

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Ryuta Shigefuku

St. Marianna University School of Medicine

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Tsunamasa Watanabe

St. Marianna University School of Medicine

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Nobuhiro Hattori

St. Marianna University School of Medicine

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