Obara, Hideaki



School of Medicine, Department of Surgery (General and Gastroenterological Surgery) (Shinanomachi)


Associate Professor

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Other Affiliation 【 Display / hide

  • School of Medicine, 感染対策室, 副センター長

Career 【 Display / hide

  • 2012.10

    Keio University School of Medicine, Department of Surgery, 専任講師

Academic Background 【 Display / hide

  • 1993.03

    Keio University School of Medicine

    University, Graduated

Academic Degrees 【 Display / hide

  • MD, PhD, Keio University, National Institution for Academic Degrees and University Evaluation, 2001.07

    Overexpression of truncated IkappaBalpha induces TNF-alpha-dependent apoptosis in human vascular smooth muscle cells.


Research Areas 【 Display / hide

  • Life Science / General surgery and pediatric surgery

Research Keywords 【 Display / hide

  • vascular regeneration

Research Themes 【 Display / hide

  • 血管内留置生体吸収性ステントの開発と実用化, 



Papers 【 Display / hide

  • Long-term outcomes of living donor liver transplantation after locoregional treatment for hepatocellular carcinoma: an experience from a single institute

    Inomata K., Yagi H., Hibi T., Shinoda M., Matsubara K., Abe Y., Kitago M., Obara H., Itano O., Kawachi S., Tanabe M., Wakabayashi G., Shimazu M., Kitagawa Y.

    Surgery Today (Surgery Today)  51 ( 3 ) 350 - 357 2021.03

    ISSN  09411291

     View Summary

    Purpose: The precise role of downstaging or bridge therapy for cirrhotic patients with hepatocellular carcinoma (HCC) beyond or within the Milan criteria (MC) before living donor liver transplantation (LDLT) remains undefined. Methods: We conducted a single-center, retrospective cohort study of 40 cirrhotic patients with HCC who underwent LDLT from 2000 to 2018. Dynamic computed tomography images at the initial presentation and immediately before LDLT as well as the final histopathological findings were reviewed to determine whether they met or exceeded MC. Results: Overall, 29 patients underwent various pre-transplant HCC treatments, including ablation and embolization (bridge therapy, n = 20; downstaging, n = 9). Of the 9 patients who were initially beyond the MC, 4 (44.4%) were successfully downstaged to within the MC. Five patients beyond the MC immediately before LDLT demonstrated a significantly worse 5-year overall survival rate than patients within the MC (16.7% vs. 82.2%, P = 0.004), regardless of the radiological HCC stage at presentation or the final pathological tumor status. All 3 recurrent patients had HCC beyond the MC immediately before transplant and died of their disease at 13, 24, and 50 months after transplantation. Conclusions: Successful downstaging for HCC cases beyond the MC provides similar outcomes to those within the MC at presentation, regardless of the histopathological findings.

  • CT screening for COVID-19 in asymptomatic patients before hospital admission

    Uchida S., Uno S., Uwamino Y., Hashimoto M., Matsumoto S., Obara H., Jinzaki M., Kitagawa Y., Hasegawa N.

    Journal of Infection and Chemotherapy (Journal of Infection and Chemotherapy)  27 ( 2 ) 232 - 236 2021.02

    ISSN  1341321X

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    Introduction: In the novel coronavirus disease (COVID-19) pandemic era, it is essential to rule out COVID-19 effectively to prevent transmission in both communities and medical facilities. According to previous reports in high prevalence areas, CT screening may be useful in the diagnosis of COVID-19. However, the value of CT screening in low prevalence areas has scarcely been reported. Methods: This report examines the diagnostic efficacy of CT screening before admission to a hospital in Tokyo. We conducted a retrospective analysis at Keio University Hospital from April 6, 2020, through May 29, 2020. We set up an outpatient screening clinic on April 6 for COVID-19, administering both PCR with nasopharyngeal swabs and chest CT for all patients scheduled for surgery under general anesthesia. Results: A total of 292 asymptomatic patients were included in this study. There were three PCR-positive patients, and they all had negative CT findings, which revealed that both the sensitivity and positive predictive value of CT (PPV) were 0%. There were nine CT-positive patients; the specificity and the negative predictive value (NPV) were 96.9% and 98.9%, respectively. Conclusion: CT screening was not useful in low prevalence areas at this time in Tokyo, even with the inclusion of the most prevalent phase. Given that the utility of CT screening depends on disease prevalence, the criteria for performing CT screening based on the prevalence of COVID-19 should be established.

  • In situ bypass and extra-anatomic bypass procedures result in similar survival in patients with secondary aortoenteric fistulas

    Janko M.R., Woo K., Hacker R.I., Baril D., Bath J., Smeds M.R., Kashyap V.S., Szeberin Z., Magee G.A., Elsayed R., Wishy A., St. John R., Beck A., Farber M., Motta F., Zhou W., Lemmon G., Coleman D., Behrendt C.A., Aziz F., Black J., Shutze W., Garrett H.E., De Caridi G., Liapis C.D., Geroulakos G., Kakisis J., Moulakakis K., Kakkos S.K., Obara H., Wang G., Rhéaume P., Davila V., Ravin R., DeMartino R., Milner R., Shalhub S., Jim J., Lee J., Dubuis C., Ricco J.B., Coselli J., Lemaire S., Fatima J., Sanford J., Yoshida W., Schermerhorn M.L., Menard M., Belkin M., Blackwood S., Conrad M., Wang L., Crofts S., Nixon T., Wu T., Chiesa R., Bose S., Turner J., Moore R., Smith J., Ciocca R., Hsu J., Czerny M., Cullen J., Kahlberg A., Setacci C., Joh J.H., Senneville E., Garrido P., Sarac T.P., Rizzo A., Go M.R., Bjorck M., Gavali H., Wanhainen A., Lawrence P.F., Chung J.

    Journal of Vascular Surgery (Journal of Vascular Surgery)  73 ( 1 ) 210 - 221.e1 2021.01

    ISSN  07415214

     View Summary

    Objective: The optimal revascularization modality in secondary aortoenteric fistula (SAEF) remains unclear in the literature. The purpose of this investigation was to determine the revascularization approach associated with the lowest morbidity and mortality using real-world data in patients with SAEF. Methods: A retrospective, multi-institutional study of SAEF from 2002 to 2014 was performed using a standardized database. Baseline demographics, comorbidities, and operative and postoperative variables were recorded. The primary outcome was long-term mortality. Descriptive statistics, Kaplan-Meier survival analysis, and univariate and multivariate analyses were performed. Results: During the study period, 182 patients at 34 institutions from 11 countries presented with SAEF (median age, 72 years; 79% male). The initial aortic procedures that resulted in SAEF were 138 surgical grafts (76%) and 42 endografts (23%), with 2 unknown; 102 of the SAEFs (56%) underwent complete excision of infected aortic graft material, followed by in situ (in-line) bypass (ISB), including antibiotic-soaked prosthetic graft (53), autogenous femoral vein (neoaortoiliac surgery; 17), cryopreserved allograft (28), and untreated prosthetic grafts (4). There were 80 patients (44%) who underwent extra-anatomic bypass (EAB) with infected graft excision. Overall median Kaplan-Meier estimated survival was 319 days (interquartile range, 20-2410 days). Stratified by EAB vs ISB, there was no significant difference in Kaplan-Meier estimated survival (P =.82). In comparing EAB vs ISB, EAB patients were older (74 vs 70 years; P =.01), had less operative hemorrhage (1200 mL vs 2000 mL; P =.04), were more likely to initiate dialysis within 30 days postoperatively (15% vs 5%; P =.02), and were less likely to experience aorta-related hemorrhage within 30 days postoperatively (3% aortic stump dehiscence vs 11% anastomotic rupture; P =.03). There were otherwise no significant differences in presentation, comorbidities, and intraoperative or postoperative variables. Multivariable Cox regression showed that the duration of antibiotic use (hazard ratio, 0.92; 95% confidence interval, 0.86-0.98; P =.01) and rifampin use at time of discharge (hazard ratio, 0.20; 95% confidence interval, 0.05-0.86; P =.03) independently decreased mortality. Conclusions: These data suggest that ISB does not offer a survival advantage compared with EAB and does not decrease the risk of postoperative aorta-related hemorrhage. After repair, <50% of SAEF patients survive 10 months. Each week of antibiotic use decreases mortality by 8%. Further study with risk modeling is imperative for this population.

  • Invasive pulmonary aspergillosis after liver transplantation: lessons from successfully treated cases and review of the literature

    Abe K., Shinoda M., Uno S., Obara H., Kitago M., Abe Y., Hishida T., Yagi H., Hasegawa Y., Kitagawa Y.

    Surgery Today (Surgery Today)   2021

    ISSN  09411291

     View Summary

    Purpose: Invasive pulmonary aspergillosis (IPA) after liver transplantation (LT) is most often fatal. We analyzed the outcomes of IPA in a single center. Methods: We reviewed, retrospectively, the medical records of recipients of living donor LT (LDLT) or deceased donor LT (DDLT) performed between 1995 and 2019 at our institute. We analyzed the incidence of IPA and assessed the treatment courses of patients treated successfully and those not treatment successfully. Results: Among 326 recipients, IPA was diagnosed in 6 (1.8%). The incidence of IPA was significantly higher in patients with acute liver failure (ALF, 9.8%) than in those without ALF (0.4%), after DDLT (8.8%) than after LDLT (1.0%), and in recipients who received preoperative steroid pulse therapy (16.0%) than in those who did not (0.7%). Complete cure of IPA was achieved in the most recent three patients, by administering voriconazole immediately after the diagnosis of IPA and performing lung resection, while the IPA lesion was single and localized. Conclusions: Patients with risk factors for IPA must be monitored closely. Our three successfully treated cases demonstrate that initiating immediate voriconazole treatment and making a calculated decision about lung resection can contribute to a favorable outcome.

  • Clinical features of irreversible rejection after allogeneic uterus transplantation in cynomolgus macaques

    Kisu I., Emoto K., Masugi Y., Yamada Y., Matsubara K., Obara H., Matoba Y., Banno K., Kato Y., Saiki Y., Itagaki I., Kawamoto I., Iwatani C., Murase M., Nakagawa T., Tsuchiya H., Ishigaki H., Urano H., Ema M., Ogasawara K., Aoki D., Nakagawa K., Shiina T.

    Scientific Reports (Scientific Reports)  10 ( 1 )  2020.12

     View Summary

    Uterus transplantation (UTx) is a potential option for women with uterine factor infertility to have a child. The clinical features indicating irreversible rejection of the uterus are unknown. In our experimental series of allogeneic UTx in cynomolgus macaques, six female macaques were retrospectively examined, which were unresponsive to treatment with immunosuppressants (i.e. irreversible rejection). Clinical features including general condition, hematology, uterine size, indocyanine green (ICG) fluorescence imaging by laparotomy, and histopathological findings of the removed uterus were evaluated. In all cases, general condition was good at the time of diagnosis of irreversible rejection and thereafter. Laboratory evaluation showed temporary increases in white blood cells, lactate dehydrogenase and C-reactive protein, then these levels tended to decrease gradually. In transabdominal ultrasonography, the uterus showed time-dependent shrinkage after transient swelling at the time of diagnosis of irreversible rejection. In laparotomy, a whitish transplanted uterus was observed and enhancement of the transplanted uterus was absent in ICG fluorescence imaging. Histopathological findings in each removed uterus showed hyalinized fibrosis, endometrial deficit, lymphocytic infiltration and vasculitis. These findings suggest that uterine transplantation rejection is not fatal, in contrast to rejection of life-supporting organs. Since the transplanted uterus with irreversible rejection atrophies naturally, hysterectomy may be unnecessary.

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Reviews, Commentaries, etc. 【 Display / hide

Research Projects of Competitive Funds, etc. 【 Display / hide

  • Evaluation of Adipose-derived Mesenchymal Stem/stromal Cell Line (ASCL) therapy for hepatic ischemia/reperfusion injury and application to liver transplantation


    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Principal investigator

  • Development of drug eluting bioresorbable stents with antiplatelet effect and protection against hepatic ischemia and reperfusion injury: application to liver transplantation


    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Principal investigator


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