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Dive into the research topics where Masanobu Usui is active.

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Featured researches published by Masanobu Usui.


Journal of Hepato-biliary-pancreatic Sciences | 2014

Paradoxical impact of the remnant pancreatic volume and infectious complications on the development of nonalcoholic fatty liver disease after pancreaticoduodenectomy

Rie Sato; Masashi Kishiwada; Naohisa Kuriyama; Yoshinori Azumi; Shugo Mizuno; Masanobu Usui; Hiroyuki Sakurai; Masami Tabata; Tomomi Yamada; Shuji Isaji

The aim of the present study was to evaluate perioperative risk factors for development of nonalcoholic fatty liver disease (NAFLD) after pancreaticoduodenectomy (PD), paying special attention to remnant pancreatic volume (RPV) and postoperative infection.


Thrombosis Research | 2013

Behavior of ADAMTS13 and Von Willebrand factor levels in patients after living donor liver transplantation

Naoki Takahashi; Hideo Wada; Masanobu Usui; Toshihiko Kobayashi; Naomi Habe-Ito; Takeshi Matsumoto; Shinji Uemoto; Tsutomu Nobori; Shuji Isaji

INTRODUCTION Thrombotic microangiopathy (TMA) is one of the important complications occurring after liver transplantation (LT), and it is suggested that a Von Willebrand factor (VWF) and ADAMTS13 may play an important role in the onset of TMA and poor outcome after LT. MATERIALS AND METHODS In 81 patients after living donor LT (LDLT), 17 patients who had both severe thrombocytopenia and hemolytic anemia with fragmented red cell were diagnosed as TMA- like syndrome (TMALS) and 10 patients died. RESULTS ADAMTS13 activities were slightly low, and plasma levels of VWF and VWF propeptide (VWFpp) antigens and the ratio of VWFpp/VWF were significantly high before LDLT. ADAMTS13 activities were significantly reduced from day 1 to day 28 after surgery, and plasma levels of VWF antigen slightly decreased on day 1 and plasma levels of VWFpp continued to be high. The ratio of VWFpp/VWF was significantly high on day 1 after surgery. The mortality was high in the patients with TMALS and the frequency of TMALS was high in non-survivors. VWF levels were significantly low and the ratio of VWFpp/VWF was significantly high in those with TMALS on day 1 after surgery. The ADAMTS13 activity was significantly low, and the VWFpp and the VWFpp/ADAMTS13 ratio were significantly high in non-survivor on day 28 after surgery. CONCLUSION These findings suggest that VWF and ADAMTS13 might therefore play an important role in the onset of TMA and poor outcome after LT. The VWFpp may therefore be a more useful marker for the diagnosis of TMALS than VWF.


Pancreas | 2016

Human Equilibrative Nucleoside Transporter 1 Expression in Endoscopic Ultrasonography-Guided Fine-Needle Aspiration Biopsy Samples Is a Strong Predictor of Clinical Response and Survival in the Patients With Pancreatic Ductal Adenocarcinoma Undergoing Gemcitabine-Based Chemoradiotherapy.

Reiko Yamada; Shugo Mizuno; Katsunori Uchida; Misao Yoneda; Kazuki Kanayama; Hiroyuki Inoue; Yasuhiro Murata; Naohisa Kuriyama; Masashi Kishiwada; Masanobu Usui; Noriko; Junya Tsuboi; Shunsuke Tano; Yasuhiko Hamada; Kyosuke Tanaka; Noriyuki Horiki; Toru Ogura; Taizo Shiraishi; Yoshiyuki Takei; Naoyuki Katayama; Shuji Isaji

ObjectivesThis study aimed to clarify whether pretreatment human equilibrative nucleoside transporter (hENT1) expressions in endoscopic ultrasonography-guided fine-needle aspiration biopsy (EUS-FNAB) specimens obtained from resectable, borderline resectable, and locally advanced unresectable pancreatic ductal adenocarcinoma (PDAC) are concordant with those in the resected specimen after gemcitabine-based chemoradiotherapy (Gem-CRT) and to validate the utility of hENT1 expression using EUS-FNAB samples as a prognostic marker. MethodsWe evaluated the relationship between hENT1 expressions assessed by immunohistochemical staining and clinical outcomes in 51 of 76 patients with PDAC who were diagnosed by EUS-FNAB and received preoperative Gem-CRT. ResultsThe concordance rate of hENT1 expressions was 89.2% (K = 0.681). Median survival time (month) in the 51 whole patients and 37 patients with resection was significantly longer in hENT1 positive than in hENT1 negative: 25.0 and 30.0 versus 9.0 and 9.0, respectively. A multivariate analysis confirmed that hENT1 expression was an independent prognostic factor in both whole patients and those with resection. Regardless of T3 and T4, hENT1-positive patients with resection had significantly better prognosis than hENT1-negative patients, whose prognosis was similar to those without resection. ConclusionsThe assessment of hENT1 expression using EUS-FNAB samples before Gem-CRT provides important information on patients with PDAC who can benefit from curative-intent resection.


Molecular Medicine Reports | 2014

The long-term effects of splenectomy and subsequent interferon therapy in patients with HCV-related liver cirrhosis

Yuji Inagaki; Kazushi Sugimoto; Katsuya Shiraki; Masahiko Tameda; Satoko Kusagawa; Keiichiro Nojiri; Suguru Ogura; Norihiko Yamamoto; Yoshiyuki Takei; Masaaki Ito; Shugo Mizuno; Masanobu Usui; Hiroyuki Sakurai; Shuji Isaji

Partial splenic embolization (PSE) or splenectomy is widely performed to increase platelet counts for interferon (IFN) therapy. The aim of the present study was to evaluate the long-term effects of splenectomy and subsequent IFN therapy in patients with hepatitis C virus (HCV)-related liver cirrhosis (LC). The present study included 19 patients with HCV-related LC who underwent splenectomy for thrombo-cytopenia caused by hypersplenism. IFN therapy was performed in all 19 patients. The effects of splenectomy and subsequent IFN therapy on peripheral blood counts, liver function, carcinogenesis and survival rates were evaluated. Splenectomy was safely performed in all patients without major complications with the exception of portal thrombosis, which, however, it did not affect liver function when treated appropriately. Thrombocytopenia improved and IFN therapy could be performed in all the patients. A sustained virological response (SVR) was not observed in patients with genotype 1 although it was observed in 75% of patients with genotype 2. Due to severe side effects, five patients did not undergo scheduled IFN therapy. Over 5 years, the mean platelet number increased from 5.2 x 10(4) to 16.8 x 10(4)/mm3 (P<0.01) and liver function improved following splenectomy (albumin, Alb: 3.5‑3.8 g/dl; total bilirubin, T-Bil: 1.0‑0.7 mg/dl; prothrombin time, PT: 74.1‑97.7%; total cholesterol; T-cho: 140‑168 mg/dl; P<0.05). Hepatocellular carcinoma (HCC) occurred in only one patient during long‑term observation and follow‑up of the patients not presenting with HCC at entry. The results of the present study demonstrate that splenectomy followed by interferon therapy could be beneficial in patients with HCV-related LC.


BioMed Research International | 2014

A New Surgical Technique of Pancreaticoduodenectomy with Splenic Artery Resection for Ductal Adenocarcinoma of the Pancreatic Head and/or Body Invading Splenic Artery: Impact of the Balance between Surgical Radicality and QOL to Avoid Total Pancreatectomy

Ryosuke Desaki; Shugo Mizuno; Akihiro Tanemura; Masashi Kishiwada; Yasuhiro Murata; Yoshinori Azumi; Naohisa Kuriyama; Masanobu Usui; Hiroyuki Sakurai; Masami Tabata; Shuji Isaji

For pancreatic ductal adenocarcinoma (PDAC) of the head and/or body invading the splenic artery (SA), we developed a new surgical technique of proximal subtotal pancreatectomy with splenic artery and vein resection, so-called pancreaticoduodenectomy with splenic artery resection (PD-SAR). We retrospectively reviewed a total of 84 patients with curative intent pancreaticoduodenectomy (PD) for PDAC of the head and/or body. These 84 patients were classified into the two groups: conventional PD (n = 66) and PD-SAR (n = 18). Most patients were treated by preoperative chemoradiotherapy (CRT). Postoperative MDCT clearly demonstrated enhancement of the remnant pancreas at 1 and 6 months in all patients examined. Overall survival rates were very similar between PD and PD-SAR (3-year OS: 23.7% versus 23.1%, P = 0.538), despite the fact that the tumor size and the percentages of UICC-T4 determined before treatment were higher in PD-SAR. Total daily insulin dose was significantly higher in PD-SAR than in PD at 1 month, while showing no significant differences between the two groups thereafter. PD-SAR with preoperative CRT seems to be promising surgical strategy for PDAC of head and/or body with invasion of the splenic artery, in regard to the balance between operative radicality and postoperative QOL.


Clinical & Developmental Immunology | 2013

Immunological aspects in late phase of living donor liver transplant patients: usefulness of monitoring peripheral blood CD4+ adenosine triphosphate activity.

Shugo Mizuno; Yuichi Muraki; Kaname Nakatani; Akihiro Tanemura; Naohisa Kuriyama; Ichiro Ohsawa; Yoshinori Azumi; Masashi Kishiwada; Masanobu Usui; Hiroyuki Sakurai; Masami Tabata; Norihiko Yamamoto; Tomomi Yamada; Katsuya Shiraki; Yoshiyuki Takei; Tsutomu Nobori; Masahiro Okuda; Shuji Isaji

Aim. To evaluate whether the combination of the peripheral blood CD4+ adenosine triphosphate activity (ATP) assay (ImmuKnow assay: IMK assay) and cytochrome P450 3A5 (CYP3A5) genotype assay is useful for monitoring of immunological aspects in the patient followup of more than one year after living donor liver transplantation (LDLT). Methods. Forty-nine patients, who underwent LDLT more than one year ago, were randomly screened by using IMK assay from January 2010 to December 2011, and the complete medical records of each patient were obtained. The CYP3A5 genotypes were examined in thirty-nine patients of them. Results. The mean ATP level of the IMK assay was significantly lower in the patients with infection including recurrence of hepatitis C (HCV) (n = 10) than in those without infection (n = 39): 185 versus 350 ng/mL (P < 0.001), while it was significantly higher in the patients with rejection (n = 4) than in those without rejection (n = 45): 663 versus 306 ng/mL (P < 0.001). The IMK assay showed favorable sensitivity/specificity for infection (0.909/0.842) as well as acute rejection (1.0/0.911). CYP3A5 genotypes in both recipient and donor did not affect incidence of infectious complications. Conclusions. In the late phase of LDLT patients, the IMK assay is very useful for monitoring immunological aspects including bacterial infection, recurrence of HCV, and rejection.


BioMed Research International | 2015

Comparative Study on the Cytoprotective Effects of Activated Protein C Treatment in Nonsteatotic and Steatotic Livers under Ischemia-Reperfusion Injury

Akitoshi Matsuda; Naohisa Kuriyama; Hiroyuki Kato; Akihiro Tanemura; Yasuhiro Murata; Yoshinori Azumi; Masashi Kishiwada; Shugo Mizuno; Masanobu Usui; Hiroyuki Sakurai; Shuji Isaji

Activated protein C (APC) has cytoprotective effects on liver ischemia-reperfusion injury (IRI). However, it is unclear whether APC is beneficial in steatotic liver IRI. We compared the cytoprotective effects of APC in nonsteatotic and steatotic liver IRI. Methods. Mice fed either normal diets (ND mice) or high fat diets (HF mice), were treated with APC or saline (control) and were performed 60 min partial IRI. Moreover, primary steatotic hepatocytes were either untreated or treated with APC and then incubated with H2O2. Results. APC significantly reduced serum transaminase levels and the inflammatory cells infiltration compared with control at 4 h in ND mice and at 24 h in HF mice. APC inhibited sinusoidal endothelial injury in ND mice, but not in HF mice. In contrast, APC activated adenosine monophosphate-activated protein kinase (AMPK) phosphorylation in HF mice, but not in ND mice. In the in vitro study, APC significantly increased AMPK phosphorylation, ATP concentration, and survival rates of hepatocytes compared with control. Conclusion. During IRI in normal liver, APC attenuated initial damage by inhibiting inflammatory cell infiltration and sinusoidal endothelial injury, but not in steatotic liver. However, in steatotic liver, APC might attenuate late damage via activation of AMPK.


Transplantation proceedings | 2016

Long-Term Influence of CYP3A5 Gene Polymorphism on Pharmacokinetics of Tacrolimus and Patient Outcome After Living Donor Liver Transplantation.

Hiroyuki Kato; Masanobu Usui; Yuichi Muraki; Akihiro Tanemura; Yasuhiro Murata; Naohisa Kuriyama; Yoshinori Azumi; Masashi Kishiwada; Shugo Mizuno; Hiroyuki Sakurai; Masahiro Okuda; Kaname Nakatani; Shuji Isaji

BACKGROUND We investigated a long-term association between donor/recipient CYP3A5 polymorphisms, pharmacokinetics of tacrolimus, and recipient outcomes in settings of living donor liver transplantation (LDLT). METHODS From February 2002 to November 2009, 67 couples of donor/recipients with tacrolimus administration, who could be genotyped for CYP3A5*3 and *1, were eligible in this study. We compared the dose-adjusted trough levels (C/D ratio) and dose/weight ratio of tacrolimus at 1 to 36 months postoperatively and recipient prognosis according to donor/recipient CYP3A5 polymorphisms; *1*1 in 7, *1*3 in 15, and *3*3 in 45, based on recipient genotype, and *1*1 in 1, *1*3 in 28, and *3*3 in 38, based on donor genotype. RESULTS On the basis of the data from C/D ratio and dose/weight ratio of tacrolimus, the recipients who had *1 allele and/or whose donor had *1allele required significantly high doses of tacrolimus with, compared with those without, all through 3 years after transplantation. These data allowed us to show the importance of not only recipient CYP3A5 polymorphisms but also donor polymorphisms to obtain the target tacrolimus blood concentration. The overall survival rates of the recipients with *1*1 (5-year survival rate: 28.6%) were significantly unfavorable, which might have been caused by over-immunosuppression, compared with those with *1*3 (5-year survival rate: 78.8%) and *3*3 genotype (5-year survival rate: 84.3%). CONCLUSIONS Immune suppressive therapy with the use of tacrolimus should be tailored on the basis of CYP3A5 genotype, which may reduce the adverse effects and improve graft outcome.


Transplantation | 2016

A Novel Predictor of Posttransplant Portal Hypertension in Adult-To-Adult Living Donor Liver Transplantation: Increased Estimated Spleen/Graft Volume Ratio.

Kazuyuki Gyoten; Shugo Mizuno; Hiroyuki Kato; Yasuhiro Murata; Akihiro Tanemura; Yoshinori Azumi; Naohisa Kuriyama; Masashi Kishiwada; Masanobu Usui; Hiroyuki Sakurai; Shuji Isaji

Background In adult living donor liver transplantation (ALDLT), graft-to-recipient weight ratio of less than 0.8 is incomplete for predicting portal hypertension (>20 mm Hg) after reperfusion. We aimed to identify preoperative factors contributing to portal venous pressure (PVP) after reperfusion and to predict portal hypertension, focusing on spleen volume-to-graft volume ratio (SVGVR). Methods In 73 recipients with ALDLT between 2002 and 2013, first we analyzed survival according to PVP of 20 mm Hg as the threshold, evaluating the efficacy of splenectomy. Second, we evaluated various preoperative factors contributing to portal hypertension after reperfusion. Results All of the recipients with PVP greater than 20 mm Hg (n = 19) underwent PVP modulation by splenectomy, and their overall survival was favorable compared with 54 recipients who did not need splenectomy (PVP ⩽ 20 mm Hg). Graft-to-recipient weight ratio had no correlation with PVP. Multivariate analysis revealed that estimated graft and spleen volume were significant factors contributing to PVP after reperfusion (P < 0.0001 and P < 0.0001, respectively). Furthermore, estimated SVGVR showed a significant negative correlation to PVP after reperfusion (R = 0.652), and the best cutoff value for portal hypertension was 0.95. Conclusions In ALDLT, preoperative assessment of SVGVR is a good predictor of portal hypertension after reperfusion can be used to indicate the need for splenectomy before reperfusion.


Hepatology Research | 2017

Role of spleen in hepatic ischemia reperfusion injury: splenic congestion during ischemia accelerates leukocytes infiltration within the liver after reperfusion.

Hiroyuki Kato; Takashi Hamada; Naohisa Kuriyama; Takahiro Ito; Shoichi Magawa; Yoshinori Azumi; Masashi Kishiwada; Shugo Mizuno; Masanobu Usui; Hiroyuki Sakurai; Shuji Isaji

The precise mechanism by which prophylactic splenectomy reduces hepatic ischemia–reperfusion injury (IRI) are still unclear. In this study, we focused on the histological changes of spleen during hepatic IRI, and tested how splenectomy provided cytoprotective effects against hepatic IRI.

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