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Dive into the research topics where Shigenori Ota is active.

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Featured researches published by Shigenori Ota.


Gut | 2013

Treatment of pancreatic fibrosis with siRNA against a collagen-specific chaperone in vitamin A-coupled liposomes

Hirotoshi Ishiwatari; Yasushi Sato; Kazuyuki Murase; Akihiro Yoneda; Ryosuke Fujita; Hiroki Nishita; Naoko Kubo Birukawa; Tsuyoshi Hayashi; Tsutomu Sato; Koji Miyanishi; Rishu Takimoto; Masayoshi Kobune; Shigenori Ota; Yasutoshi Kimura; Koichi Hirata; Junji Kato; Yoshiro Niitsu

Background and objective Fibrosis associated with chronic pancreatitis is an irreversible lesion that can disrupt pancreatic exocrine and endocrine function. Currently, there are no approved treatments for this disease. We previously showed that siRNA against collagen-specific chaperone protein gp46, encapsulated in vitamin A-coupled liposomes (VA-lip-siRNAgp46), resolved fibrosis in a model of liver cirrhosis. This treatment was investigated for pancreatic fibrosis induced by dibutyltin dichloride (DBTC) and cerulein in rats. Methods Specific uptake of VA-lip-siRNAgp46, conjugated with 6′-carboxyfluorescein (FAM) by activated pancreatic stellate cells (aPSCs), was analysed by fluorescence activated cell sorting (FACS). Intracellular distribution of VA-lip-siRNAgp46-FAM was examined by fluorescent microscopy. Suppression of gp46 expression by VA-lip-siRNAgp46 was assessed by immunoblotting. Collagen synthesis in aPSCs was assayed by dye-binding. Specific delivery of VA-lip-siRNAgp46 to aPSCs in DBTC rats was verified following intravenous VA-lip-siRNA-FAM and 3H-VA-lip-siRNAgp46. The effect of VA-lip-siRNA on pancreatic histology in DBTC- and cerulein-treated rats was determined by Azan-Mallory staining and hydroxyproline content. Results FACS analysis revealed specific uptake of VA-lip-siRNAgp46-FAM through the retinol binding protein receptor by aPSCs in vitro. Immunoblotting and collagen assay verified knockdown of gp46 and suppression of collagen secretion, respectively, by aPSCs after transduction of VA-lip-siRNAgp46. Specific delivery of VA-lip-siRNAgp46 to aPSCs in fibrotic areas in DBTC rats was confirmed by fluorescence and radioactivity 24 h after the final injection. 10 systemic VA-lip-siRNAgp46 treatments resolved pancreatic fibrosis, and suppressed tissue hydroxyproline levels in DBTC- and cerulein-treated rats. Conclusion These data suggest the therapeutic potential of the present approach for reversing pancreatic fibrosis.


World Journal of Gastroenterology | 2014

Propensity score analysis demonstrated the prognostic advantage of anatomical liver resection in hepatocellular carcinoma

Masayuki Ishii; Toru Mizuguchi; Masaki Kawamoto; Makoto Meguro; Shigenori Ota; Toshihiko Nishidate; Kenji Okita; Yasutohsi Kimura; Thomas Hui; Koichi Hirata

AIM To compare the prognoses of hepatocellular carcinoma (HCC) patients that underwent anatomic liver resection (AR) or non-anatomic liver resection (NAR) using propensity score-matched populations. METHODS Between January 2002 and December 2010, 268 consecutive HCC patients, including 110 and 158 patients that underwent AR and NAR, respectively, were retrospectively enrolled in this study. Forty-four patients from each group were selected and matched using logistic multivariate analysis followed by propensity score analysis. RESULTS In the whole analysis set, the histological background of the liver, liver function, and tumor marker levels differed significantly among the groups. Although the overall survival (OS) and recurrence-free survival rates of the two groups did not differ significantly in the whole analysis set, the OS of the AR group was significantly longer than that of the NAR group after propensity matching (76.2 ± 6.3 mo vs 58.9 ± 6.3 mo; P = 0.0039). Although AR (HR = 0.456, P = 0.039) was found to be a prognostic factor in the univariate analysis, only vascular invasion (HR = 0.228, P = 0.002) and the hepatocyte growth factor level (HR = 52.366, P = 0.035) were subsequently found to be independent prognostic factors. CONCLUSION AR conveys a survival advantage over NAR in specific subpopulations of HCC patients with tumors of less than 5 cm in diameter, single tumor, and good liver function.


World Journal of Hepatology | 2014

Comprehensive review of post-liver resection surgical complications and a new universal classification and grading system

Masayuki Ishii; Toru Mizuguchi; Kohei Harada; Shigenori Ota; Makoto Meguro; Tomomi Ueki; Toshihiko Nishidate; Kenji Okita; Koichi Hirata

Liver resection is the gold standard treatment for certain liver tumors such as hepatocellular carcinoma and metastatic liver tumors. Some patients with such tumors already have reduced liver function due to chronic hepatitis, liver cirrhosis, or chemotherapy-associated steatohepatitis before surgery. Therefore, complications due to poor liver function are inevitable after liver resection. Although the mortality rate of liver resection has been reduced to a few percent in recent case series, its overall morbidity rate is reported to range from 4.1% to 47.7%. The large degree of variation in the post-liver resection morbidity rates reported in previous studies might be due to the lack of consensus regarding the definitions and classification of post-liver resection complications. The Clavien-Dindo (CD) classification of post-operative complications is widely accepted internationally. However, it is hard to apply to some major post-liver resection complications because the consensus definitions and grading systems for post-hepatectomy liver failure and bile leakage established by the International Study Group of Liver Surgery are incompatible with the CD classification. Therefore, a unified classification of post-liver resection complications has to be established to allow comparisons between academic reports.


World Journal of Gastroenterology | 2015

Prognostic roles of preoperative α-fetoprotein and des-γ-carboxy prothrombin in hepatocellular carcinoma patients

Makoto Meguro; Toru Mizuguchi; Toshihiko Nishidate; Kenji Okita; Masayuki Ishii; Shigenori Ota; Tomomi Ueki; Emi Akizuki; Koichi Hirata

AIM To clarify the utility of using des-γ-carboxy prothrombin (DCP) and α-fetoprotein (AFP) levels to predict the prognosis of hepatocellular carcinoma (HCC) in patients with hepatitis B virus (HBV) and the hepatitis C virus (HCV) infections. METHODS A total of 205 patients with HCC (105 patients with HBV infection 100 patients with HCV infection) who underwent primary hepatectomy between January 2004 and May 2012 were enrolled retrospectively. Preoperative AFP and DCP levels were used to create interactive dot diagrams to predict recurrence within 2 years after hepatectomy, and cutoff levels were calculated. Patients in the HBV and HCV groups were classified into three groups: a group with low AFP and DCP levels (LL group), a group in which one of the two parameters was high and the other was low (HL group), and a group with high AFP and DCP levels (HH group). Liver function parameters, the postoperative recurrence-free survival rate, and postoperative overall survival were compared between groups. The survival curves were compared by log-rank test using the Kaplan-Meier method. Multivariate analysis using a Cox forward stepwise logistic regression model was conducted for a prognosis. RESULTS The preoperative AFP cutoff levels for recurrence within 2 years after hepatectomy in the HBV and HCV groups were 529.8 ng/mL and 60 mAU/mL, respectively; for preoperative DCP levels, the cutoff levels were 21.0 ng/mL in the HBV group and 67 mAU/mL in the HCV group. The HBV group was significantly different from the other groups in terms of vascular invasion, major hepatectomy, volume of intraoperative blood loss, and surgical duration. Significant differences were found between the LL group, the HL group, and the HH group in terms of both mean disease-free survival time (MDFST) and mean overall survival time (MOST): 64.81 ± 7.47 vs 36.63 ± 7.62 vs 18.98 ± 6.17 mo (P = 0.001) and 85.30 ± 6.55 vs 59.44 ± 7.87 vs 46.57 ± 11.20 mo (P = 0.018). In contrast, the HCV group exhibited a significant difference in tumor size, vascular invasion, volume of intraoperative blood loss, and surgical duration; however, no significant difference was observed between the three groups in liver function parameters except for albumin levels. In the LL group, the HL group, and the HH group, the MDFST was 50.09 ± 5.90, 31.01 ± 7.21, and 14.81 ± 3.08 mo (log-rank test, P < 0.001), respectively, and the MOST was 79.45 ± 8.30, 58.82 ± 7.56, and 32.87 ± 6.31 mo (log-rank test, P < 0.001), respectively. CONCLUSION In the HBV group, the prognosis was poor when either AFP or DCP levels were high. In the HCV group, the prognosis was good when either or both levels were low; however, the prognosis was poor when both levels were high. High levels of both AFP and DCP were an independent risk factor associated with tumor recurrence in the HBV and HCV groups. The relationship between tumor marker levels and prognosis was characteristic to the type of viral hepatitis.


Surgery Today | 2016

Trials of vaccines for pancreatic ductal adenocarcinoma: Is there any hope of an improved prognosis?

Toru Mizuguchi; Toshihiko Torigoe; Fukino Satomi; Hiroaki Shima; Goro Kutomi; Shigenori Ota; Masayuki Ishii; Hiroshi Hayashi; Sumiyo Asakura; Yoshihiko Hirohashi; Makoto Meguro; Yasutoshi Kimura; Toshihiko Nishidate; Kenji Okita; Masaho Ishino; Atsushi Miyamoto; Masamitsu Hatakenaka; Noriyuki Sato; Koichi Hirata

Pancreatic tumors are chemoresistant and malignant, and there are very few therapeutic options for pancreatic cancer, as the disease is normally diagnosed at an advanced stage. Although attempts have been made to develop vaccine therapies for pancreatic cancer for a couple of decades, none of the resultant protocols or regimens have succeeded in improving the clinical outcomes of patients. We herein review vaccines tested within the past few years, including peptide, biological and multiple vaccines, and describe the three sets of criteria used to evaluate the therapeutic activity of vaccines in solid tumors.


Surgery Today | 2015

The impact of aging on morbidity and mortality after liver resection: a systematic review and meta-analysis

Toru Mizuguchi; Masaki Kawamoto; Makoto Meguro; Kenji Okita; Shigenori Ota; Masayuki Ishii; Tomomi Ueki; Toshihiko Nishidate; Yasutoshi Kimura; Tomohisa Furuhata; Koichi Hirata

Abstract Surgery involving elderly patients is becoming increasingly common due to the rapid aging of societies all over the world. The objective of this study was to elucidate the prognostic differences between elderly and young patients who undergo liver resection. A systematic review based on the PRISMA flow diagram was conducted. Ovid Medline and PubMed were used to search for relevant literature published between January 2000 and March 2013, and the modified MINORS score was used to assess the methodological quality. In cases of hepatocellular carcinoma and miscellaneous liver tumors, the morbidity and mortality rate did not differ significantly between the elderly and young patients. For patients with colorectal metastatic liver cancer, the mortality of the young patients was 2.7 times lower than that of elderly patients. Our review of high-quality retrospective studies was able to elucidate the clinical risks of age on the outcomes after liver surgery in specific patient populations.


Hepato-gastroenterology | 2012

Serum antithrombin III level is well correlated with multiple indicators for assessment of liver function and diagnostic accuracy for predicting postoperative liver failure in hepatocellular carcinoma patients.

Toru Mizuguchi; Masaki Kawamoto; Makoto Meguro; Seiichi Son; Yukio Nakamura; Kohei Harada; Toshihito Shibata; Shigenori Ota; Koichi Hirata

BACKGROUND/AIMS Evaluation of preoperative hepatic reserve is critical to avoid a fatal clinical course such as liver failure. We retrospectively evaluated 158 consecutive hepatocellular carcinoma (HCC) patients who underwent initial hepatectomy. The aim of this study was to determine the correlations of multiple indicators for assessment of liver function before hepatectomy. Furthermore, diagnostic probability for the pathological background and prediction of postoperative liver failure/dysfunction was compared between the antithrombin (AT) III level and indocyanine green retention rate at 15 minutes (ICGR15). METHODOLOGY Between January 2001 and March 2008, 158 HCC patients who underwent initial hepatectomy were enrolled in this study. Spearmans correlation coefficients (r values) were obtained for 15 clinical laboratory tests including ATIII and ICGR15. Receiver operating characteristic (ROC) curve analysis was used for calculating the probability and predictive ability of the tests. RESULTS All 158 consecutive HCC patients were eligible for hepatectomy based on the Japanese guideline. ATIII is correlated with 13 of 14 other clinical tests, including albumin, bilirubin, prothrombin time, rapid turnover proteins, HGF, ICGR15 and others. The diagnostic probabilities to distinguish between normal liver and other pathological backgrounds of ATIII and ICGR15 were significantly different. The specificity of ATIII to predict postoperative liver failure/dysfunction was higher than that of ICGR15. CONCLUSIONS The serum ATIII level before hepatectomy is valuable to estimate the pathological background and predict postoperative liver failure/ dysfunction. It should be possible to use ATIII as an additional indicator for liver function and substitute for ICGR15 in the future.


Surgery | 2011

Cluster analysis of indicators of liver functional and preoperative low branched-chain amino acid tyrosine ration indicate a high risk of early recurrence in analysis of 165 hepatocellular carcinoma patients after initial hepatectomy

Yukio Nakamura; Toru Mizuguchi; Masaki Kawamoto; Makoto Meguro; Kohei Harada; Shigenori Ota; Koichi Hirata

BACKGROUND Cluster analysis is used for dividing many prognostic indicators, including liver function, tumor progression, and operative variables, into specific clusters. The albumin (ALB), hepatocyte growth factor (HGF), and branched chain amino-acid to tyrosine ratio (BTR) may represent the severity of liver disease and function of the hepatic reserve. We developed the ALB-BTR and HGF-BTR classifications depending on each level to find specific unique subgroups. Our aim was to identify specific subgroups destined for favorable and poor prognoses after initial hepatectomy. METHODS Between 2002 and 2008, 165 patients were analyzed retrospectively. Liver function indicators, including BTR, tumor-related factors, and operative variables, were evaluated by cluster analysis with Wards criterion. The ALB-BTR classification was divided into 4 groups depending on ALB (cutoff value, 4.0 g/dL) and BTR (cutoff value, 6.0). The HGF-BTR classification was also divided into 4 groups depending on HGF (cutoff value, 0.35 ng/mL) and BTR (cutoff value, 6.0). The prognoses of the subgroups were compared by the log-rank test. RESULTS Cluster analysis divided multiple indicators into 5 different clusters. In each cluster, we further analyzed subgroups using the ALB-BTR and HGF-BTR classification. Mean recurrence-free survival times in ALB-GI (19.1 ± 2.4 months) and HGF-GIII (29.4 ± 3.8 months) were less than their mean overall survival times. CONCLUSION Cluster analysis is useful to find similar and different indicators. Even though liver function was well preserved, low BTR could identify early recurrence in hepatocellular carcinoma patients after resection.


Journal of Hepato-biliary-pancreatic Sciences | 2012

Area between the hepatic and heart curves of 99mTc-galactosyl-human serum albumin scintigraphy represents liver function and disease progression for preoperative evaluation in hepatocellular carcinoma patients

Kohei Harada; Toru Mizuguchi; Yoshimi Katagiri; Masaki Kawamoto; Yukio Nakamura; Makoto Meguro; Shigenori Ota; Shigeru Sasaki; Koji Miyanishi; Tomoko Sonoda; Mitsuru Mori; Yasuhisa Shinomura; Junji Kato; Koichi Hirata

Background/purposeWe developed software to calculate the pixels of interest in the area between the hepatic and heart curves (ABC) of 99mTc-galactosyl human serum albumin (GSA) scintigraphy. The aim of this study was to examine the accuracy of the ABC to evaluate liver function before hepatectomy.MethodsBetween January 2005 and December 2010, 205 consecutive patients who underwent initial hepatectomy were enrolled in this study. The ABC was calculated using original computer software. The area under the receiver operating characteristic curve (AUC) was calculated for evaluation of Child–Pugh score grade B (Child B), pathological chronic hepatitis (CH), and liver cirrhosis (LC).ResultsThe AUC of any indicator for Child B was more than 0.900 except bilirubin. The AUC of ABC for CH and LC (AUC 0.734 each) was comparable to those of HH15 (clearance index; AUC 0.704 and 0.700, respectively) and LHL15 (receptor index; AUC 0.703 and 0.706, respectively) in multiple receiver operating characteristic comparison.ConclusionsWe have developed a novel liver function indicator, the ABC, to count radioactivity in sequence. The ABC reflects liver function according to pathological deterioration of the liver. Although the ABC gave no significant advantage compared to HH15 and LHL15, it improved the AUC evaluation by 0.028–0.034.


Surgery | 2013

Continuous monitoring of central venous oxygen saturation predicts postoperative liver dysfunction after liver resection

Makoto Meguro; Toru Mizuguchi; Masaki Kawamoto; Yukio Nakamura; Shigenori Ota; Kazuharu Kukita; Masayuki Ishii; Hiroomi Tatsumi; Koichi Hirata

BACKGROUND We examined whether the data obtained by monitoring central venous oxygen saturation (ScvO2) and/or stroke volume variation (SVV) during hepatectomy, as measured with the FloTrac/Vigileo system, can predict postoperative liver dysfunction. METHODS This study included 33 patients with normal liver function who underwent hepatectomy between December 2007 and August 2010. Baseline ScvO2 and baseline SVV, as control values, were defined as the mean of ScvO2 and SVV, respectively, measured with the FloTrac/Vigileo system before hepatectomy. ScvO2 decrease (ΔScvO2) was defined as the difference between the baseline ScvO2 and the lowest intraoperative ScvO2 and SVV increase (ΔSVV) was defined as the difference between the baseline SVV and the highest intraoperative SVV. Moreover, mean ScvO2 and mean SVV were defined as the means of all ScvO2 and SVV values measured during surgery, respectively. We examined correlations of the new parameters with the highest postoperative values of total bilirubin (T. Bil). RESULTS The cutoff values for ΔScvO2 and mean SVV for predicting the highest postoperative T. Bil level to be ≥ 3.0 mg/dL with the highest sensitivity and specificity were found to be 10.2% and 13.6%, respectively. The areas under curve in receiver-operating-characteristic analysis of ΔScvO2 and mean SVV were 0.797 and 0.757, respectively, showing significant differences. CONCLUSION Our results suggest that ΔScvO2 and mean SVV can predict postoperative liver dysfunction. When ΔScvO2 and mean SVV exceed 10.2% and 13.6%, respectively, we advocate that adequate attention be paid to postoperative liver dysfunction, and that early intraoperative general circulatory management measures be implemented as needed.

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Koichi Hirata

Sapporo Medical University

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Makoto Meguro

Sapporo Medical University

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Toru Mizuguchi

Sapporo Medical University

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Masaki Kawamoto

Sapporo Medical University

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Kenji Okita

Sapporo Medical University

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Masayuki Ishii

Sapporo Medical University

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Yukio Nakamura

Sapporo Medical University

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Yasutoshi Kimura

Sapporo Medical University

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Kohei Harada

Sapporo Medical University

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