Details of a Researcher - Obara, Hideaki

Papers - Obara, Hideaki

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An operator assistance control system for skill enhancement and safety assurance in cascade tank systems

Ishida, R; Inoue, M; Ishihara, S; Obara, H

SICE JOURNAL OF CONTROL MEASUREMENT AND SYSTEM INTEGRATION 19 ( 1 ) 2026.12

ISSN 1882-4889

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R0 Resection for Pediatric Malignancies Involving the Inferior Vena Cava: A Multidisciplinary Approach

Yamada, Y; Sato, M; Kondo, A; Kumagai, T; Sugiyama, Y; Shirosaki, K; Kano, M; Kato, M; Hayashi, M; Fujimura, N; Hasegawa, Y; Abe, Y; Obara, H; Fujino, A

PEDIATRIC BLOOD & CANCER 73 S73 - S74 2026.04

ISSN 1545-5009

Early Clinical Results From the Japanese Prospective Multicenter Study to Evaluate Zenith Alpha Abdominal Stent Graft for Abdominal Aortic Aneurysm (JUSTICE) Registry Demonstrate Acceptable Limb Patency at 12 Months

Fujimura N., Ichihashi S., Shibata T., Matsumura H., Watanabe M., Morikage N., Kurimoto Y., Banno H., Uchiyama H., Obara H.

Journal of Endovascular Therapy 33 ( 1 ) 227 - 235 2026.02

ISSN 15266028

Purpose: Recent reports of the Zenith Alpha abdominal endovascular graft (Zenith Alpha AAA, Cook, Inc., Bloomington, Indiana) have demonstrated an unexpectedly high incidence of limb graft occlusion (LGO). The purpose of this study was to prospectively evaluate the performance of the Zenith AAA in Japan, with a specific focus on LGO. Materials and methods: All endovascular aneurysm repairs (EVARs) for abdominal aortic aneurysms performed using the Zenith Alpha AAA from July 2020 to October 2021 in 23 Japanese hospitals were prospectively evaluated. All computed tomographic images were analyzed in the core laboratory. Late complications were defined as any aneurysm-related events occurring >30 days after EVAR, including aneurysm sac enlargement of >5 mm and any reinterventions performed. Endoleaks without sac enlargement or reintervention were excluded as late complications. Results: During the study period, 147 EVARs were performed using the Zenith Alpha AAA. The mean patient age was 76.5±7.7 years, 84.4% of patients were male, and the mean aneurysm diameter was 52.4±9.2 mm. Instruction-for-use violations were observed in 76 patients (51.7%), primarily associated with a severely angulated proximal neck (>60°). There were six intraoperative complications and 62 additional intraoperative treatments reported, most of which involved preemptive coil embolization of the inferior mesenteric artery (37 cases). Technical success, defined as the absence of type 1 or 3 endoleaks on final angiography, was achieved in 99.3% of patients. At 12 months, there was only one case of type 1/3 endoleak (0.8%) and one aneurysm sac enlargement exceeding 5 mm (0.8%); however, a high incidence of type 2 endoleaks was observed in 35.2% of patients, and aneurysm sac regression exceeding 5 mm was achieved in 30.1% of patients. Nine late complications were observed, and the rate of freedom from late complications at 12 months was 93.5%, encompassing four LGOs and one limb graft stenosis (3.4%). Conclusions: In contrast to recent reports, our Japanese multicenter prospective study demonstrated satisfactory early clinical results, including an acceptable LGO rate, for the low-profile Zenith Alpha AAA. Long-term follow-ups will be performed to confirm the persistence of these outcomes. Clinical Impact: This study prospectively evaluated the performance of 147 Zenith Alpha AAAs used for endovascular aneurysm repair with core-lab adjudication focusing especially on limb graft occlusion (LGO). At 12 months, aneurysm sac regression exceeding 5 mm was achieved in 30.1% of patients, and there was only one type 1/3 endoleak, one aneurysm sac enlargement (>5 mm), and nine late complications including five LGOs (3.4%), resulting in rate of freedom from late complications at 93.5%. Satisfactory early clinical results, including an acceptable rate of LGO can be achieved, particularly with cautious usage of the Zenith Alpha Spiral-Z Endovascular Leg.” 5mm), and nine late complications including five LGOs (3.4%), resulting in rate of freedom from late complications at 93.5%. Satisfactory early clinical results, including an acceptable rate of LGO can be achieved, particularly with cautious usage of the Zenith Alpha Spiral-Z Endovascular Leg.

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Validation of novel scoring systems for acute decompensated cirrhosis identifies PBC as an independent poor prognostic factor: a single-center Japanese cohort study

Nakadai Y., Ojiro K., Kasuga R., Chu P.S., Ueno M., Tabuchi T., Taniki N., Usui S., Hasegawa Y., Abe Y., Kitago M., Obara H., Kanai T., Nakamoto N.

Journal of Gastroenterology 61 ( 1 ) 85 - 95 2026.01

ISSN 09441174

Background: The Model for End-Stage Liver Disease 3.0 (MELD 3.0) was developed in the United States to improve prioritization for liver transplantation (LT); however, its utility in Japanese patients with liver cirrhosis (LC) and acute decompensation (AD) remains invalidated. Methods: We retrospectively analyzed 312 patients with LC and first-time AD admitted to our institution between 2012 and 2022. Prognostic accuracy of MELD 3.0 was evaluated at 90 and 180 days after admission by comparison with other predictive models. Prognoses according to cirrhosis etiology and contributing factors were also examined. Results: MELD 3.0 demonstrated superior prognostic accuracy at day 180 (C-index: 0.770) compared to the original MELD and MELD Na, although its C-index up to day 90 was comparable to that of MELD and MELD Na. A cut-off value of MELD 3.0 > 20.5 predicted LT or liver-related death at day 180. Patients with primary biliary cholangitis (PBC) had poorer outcomes than non-PBC cases through 180 days and remained an independent risk factor in the Cox proportional hazards model incorporating MELD 3.0. A progressive increase in both MELD 3.0 and total bilirubin from day 0 to day 90 after AD was observed specifically in the PBC group, which may have been associated with the poor prognosis at day 180. Conclusions: MELD 3.0 was effective in predicting 180-day outcomes in Japanese patients with LC and AD. Progressive bilirubin elevation in PBC may be associated with poor prognosis. These findings suggest that early consideration of LT is warranted in patients with PBC.

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Retroperitoneal Abdominal Aortic Repair With the da Vinci Single Port System: A Porcine Model Feasibility Study

Takayama, T; Stein, H; Obara, H; Kudo, T; Preuss, M; Berndt, R; Debus, SE; Komiya, T; Kaneta, H; Thaveau, F

EJVES VASCULAR FORUM 65 25 - 31 2026

ISSN 2666-688X

Objective: Robotic surgery is rarely used in vascular surgery but has demonstrated significant potential compared with open or laparoscopic techniques in reports of abdominal aortic surgery. Enabling a standardised retroperitoneal approach (RPA) to abdominal aortic repair might reduce the peri-operative mortality and morbidity rates associated with a transabdominal approach. The aim of this experimental study was to establish surgical techniques for robotically assisted infrarenal abdominal aortic repair using a single port RPA. Methods: Retroperitoneal abdominal aortic repair was performed in four live porcine models by a group of experienced and novice robotic surgeons. The procedures were performed using the da Vinci SP (single port) surgical system (Intuitive Surgical Inc., Sunnyvale, CA, USA). Polytetrafluoroethylene grafts (W.L. Gore & Associates, Inc., Newark, DE, USA) were implanted after aortic resection. Operating times for the main procedure steps were recorded. Results: Abdominal aortic repair was feasible in all porcine models applying an RPA through a single incision with the da Vinci SP system. Creating the retroperitoneal access and docking the da Vinci SP was quick, with durations ranging from eight to 20 minutes. Proximal and distal anastomoses were completed in 26 minutes (range 19–33 minutes) and 31.3 minutes (range 23–42 minutes), respectively. In porcine models 2–4, the anastomoses were patent without haemorrhage, with aortic pulsations confirmed on release of the cross clamps. Porcine model 1 was pulseless owing to uncontrolled haemorrhage caused by left external iliac artery penetration at the end of the procedure, and patency could not be tested. Conclusion: Retroperitoneal single port robotic aortic repair was technically feasible with high accuracy in live porcine models. Anastomotic times were reasonable and surgeon comfort level was adequate, which may enable transfer into clinical routine in the future when true clinical benefits will need to be proven in additional studies.

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A novel tissue-engineered stent graft combining decellularized scaffold and bioresorbable stent: a pilot feasibility study in a porcine model

Shimogawara T., Matsubara K., Tajima K., Shimoda M., Yagi H., Obara H., Kitagawa Y.

Organogenesis 22 ( 1 ) 2610591 2026

ISSN 15476278

Endovascular aneurysm repair (EVAR) is a widely accepted treatment for aortic pathologies owing to its minimally invasive nature. However, long-term complications, such as stent graft migration and infection, remain unresolved, primarily due to the persistent presence of synthetic materials and limited tissue integration. This pilot study evaluated the feasibility of a novel tissue-engineered stent graft (TESG) combining a bioresorbable poly-L-lactic acid (PLLA) stent with decellularized porcine veins. The veins were processed using a sodium dodecyl sulfate and the Triton X-100 decellularization protocol. Histological and ultrastructural analyses confirmed effective cell removal while preserving extracellular matrix components. Quantitative deoxyribonucleic acid (DNA) analysis showed a > 97% reduction in DNA content. The TESGs were assembled by suturing the decellularized veins into bioresorbable PLLA stents and implanted into porcine iliac arteries (n = 3). Commercially available prosthetic grafts were used as control implants to evaluate differences in tissue responses. Graft patency and morphology were assessed at implantation and on postoperative day 14 using angiography and intravascular ultrasonography. All TESGs remained patent, with no evidence of thrombosis or aneurysmal changes. Histological analysis revealed early endothelialization and smooth muscle cell infiltration within the TESG wall, in contrast to the prosthetic graft controls, which lacked comparable cellular integration. This study demonstrated the short-term feasibility and biological compatibility of a fully bioresorbable TESG. Although long-term outcomes remain to be established, these results support further development of TESG to reduce late complications through improved tissue integration and avoidance of permanent synthetic materials.

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Comparison of vascular remodeling between a bioresorbable poly-L-lactic acid scaffold and a bare metal stent: a 6-month angiography and intravascular ultrasound analysis in porcine iliac arteries

Hayashi K., Obara H., Fujimura N., Masugi Y., Sekimoto Y., Matsubara K., Kitagawa Y.

Organogenesis 22 ( 1 ) 2630543 2026

ISSN 15476278

Animal experimental studies involving the Igaki-Tamai stent (ITS), a bioresorbable poly-l-lactic acid scaffold, in peripheral arteries are limited, and existing studies evaluated only short-term (3-month) outcomes. This study compared arterial responses associated with the ITS and bare metal stent (BMS) over 6 months using intravascular ultrasound (IVUS) analysis and evaluated feasibility in porcine iliac arteries. Four miniature pigs underwent stent implantation with the ITS in the right iliac artery and the BMS in the left iliac artery. Follow-up evaluations at 6, 12, and 24 weeks included angiographic and IVUS analyses to assess neointimal hyperplasia, percent area stenosis (%AS), and percent in-stent volume obstruction (%VO). Histological analysis was performed to evaluate tissue injury and inflammation scores. At 6 weeks, the neointimal area did not differ significantly between the ITS and BMS groups (8.49 ± 2.10 mm² vs 13.47 ± 6.67 mm², P =.205). However, the ITS group exhibited a significantly smaller neointimal area at 12 weeks (6.87 ± 1.15 mm² vs 20.65 ± 10.99 mm², P =.050) and 24 weeks (5.20 ± 0.85 mm² vs 22.32 ± 12.03 mm², P =.042). %AS and %VO were significantly lower in the ITS group at all follow-ups. The ITS group showed reduced tissue damage (injury score: 0.80 ± 0.430 vs 1.74 ± 0.908, P <.001) and inflammation (inflammation score: 1.25 ± 0.516 vs 1.67 ± 0.832, P <.001) compared with the BMS group. The ITS was associated with reduced vessel injury, lower inflammatory response, and favorable luminal remodeling over 6 months in healthy porcine iliac arteries.

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Open surgical conversion after endovascular aneurysm repair in Japan: Indications and outcomes from a multicenter study (JAST-CONVERT)

Morisaki K., Sano M., Miyake K., Kikuchi S., Shirasu T., Shibata T., Fukushima S., Takeuchi Y., Fujimura N., Matsubara Y., Orimoto Y., Natsume K., Omori M., Obara H., Azuma N.

Journal of Vascular Surgery 2026

ISSN 07415214

Objective: This study aimed to evaluate indications and outcomes of open surgical conversion (OSC) after endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm using a multicenter registry in Japan. Methods: Thirteen vascular centers retrospectively reviewed patients who underwent OSC after prior EVAR between 2006 and 2024. Baseline characteristics, indications, procedural details, and outcomes were analyzed. The primary end point was 30-day mortality. Secondary end points were overall survival, aneurysm-related mortality, and freedom from retreatment. Results: A total of 208 patients (85.6% males; median age, 78 years) were included. The median abdominal aortic aneurysm diameter was 62 mm. The median interval from initial EVAR to OSC was 5.2 years. Indications for OSC were type II endoleak with sac enlargement (47.1%), type I endoleak (23.1%), type V endoleak with sac enlargement (13.0%), infection (10.1%), and type III endoleak (9.6%). The most frequently used stent graft was the Excluder, followed by Endurant and Zenith. Complete stent graft removal was performed in 41 patients, partial removal in 51, and 116 underwent OSC with stent graft preservation. Thirty-eight patients (18.3%) presented with rupture and 48 (23.1%) underwent urgent OSC. The 30-day mortality rate was 4.3% in the overall cohort, 2.4% in nonruptured cases, and 13.2% in ruptured cases. Rupture was a risk factor for 30-day mortality (hazard ratio, 5.93; 95% confidence interval, 1.59-22.1; P = .008). At 10 years, overall survival and aneurysm-related mortality were 58.4% and 14.8%, respectively, and freedom from retreatment rate was 87.5% at 10 years. Conclusions: Type II endoleak was the leading common indication for OSC after EVAR in this multicenter retrospective study in Japan. Rupture at OSC markedly increased 30-day mortality, even in patients with type II endoleak. Further studies are needed to refine elective indications for OSC to prevent aneurysmal rupture and avoid treatment delay.

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Safety and efficacy of long-shelf-life allogeneic adipose-derived mesenchymal stem cell line-derived platelet-like cells for refractory foot ulcers: A translational preclinical and phase 1/2a study

Obara H., Matsubara K., Fujimura N., Matsubara Y., Ono-Uruga Y., Yazawa M., Okui J., Sato Y., Kitagawa Y.

Regenerative Therapy 30 606 - 615 2025.12

ISSN 2352-3204

Introduction: Refractory foot ulcers, characterized by prolonged healing and frequent recurrences, challenge existing therapies such as revascularization and compression, which typically fail to prevent amputation. We developed adipose-derived mesenchymal stem cell line-derived platelet-like cells (ASCL-PLCs) for refractory ulcers that are long-lasting and readily available. Methods: A translational preclinical investigation and phase 1/2a first-in-human clinical study assessed the safety and efficacy of a novel allogeneic ASCL-PLC treatment for refractory foot ulcers. In the pre-clinical phase, ASCL-PLCs were cryopreserved for 9 months and then thawed to measure cytokine release after calcium chloride stimulation. The therapeutic efficacy was evaluated in a diabetic mouse wound model, comparing ASCL-PLC treatment with vehicle control. The clinical trial involved topically applying ASCL-PLCs (1.5 × 10<sup>8</sup> cells/cm<sup>2</sup>) to the ulcers of four patients (two ischemic, two venous) on days 0, 14, and 28, with safety and efficacy monitored based on adverse events, ulcer size reduction, epithelialization time, and pain score changes. Results: ASCL-PLCs maintained considerable cytokine-releasing activity even after long-term cryopreservation. In the diabetic mouse skin defect model, treatment with ASCL-PLCs substantially enhanced wound closure compared with the controls, demonstrating potent wound-healing capabilities. In the clinical trial, all patients exhibited notable ulcer size reduction without serious adverse events; three achieved epithelialization within 6 months, along with improvements in pain and quality of life without a negative impact on local blood flow. Conclusions: ASCL-PLCs are safe and a promising therapeutic option for refractory ulcers and can potentially reduce amputation rates, improve patient outcomes, and minimize the socioeconomic impact due to chronic wounds. Their long shelf life and cryopreservation stability make wound management practical and accessible. Moreover, their efficacy with simple topical application suggests a minimally invasive strategy suitable for outpatient care. Further large-scale trials are recommended. This study was registered with the Japan Registry of Clinical Trials (jRCT ID: jRCTa030200053; on June 18, 2020, https://jrct.mhlw.go.jp/en-latest-detail/jRCTa030200053).

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Editor's Choice – Comparison of Prognosis in Chronic Limb Threatening Ischaemia after Revascularisation versus Non-revascularisation Treatment: Analysis of Japanese Regional Insurance Claims

Shintani T., Nakatani E., Kaneda H., Hawke P., Obara H., Usui T.

European Journal of Vascular and Endovascular Surgery 70 ( 6 ) 800 - 808 2025.12

ISSN 10785884

Objective: While the prevailing practice for treating chronic limb threatening ischaemia (CLTI) is revascularisation, there is a limited understanding of disease progression in patients with CLTI who do not undergo this intervention. This study compared the prognosis of CLTI patients with tissue loss who underwent revascularisation with the prognosis of those who were managed with non-revascularisation treatment, investigating the efficacy of revascularisation in improving the outcome of patients with CLTI. Methods: Utilising the Shizuoka Kokuho Database, a regionally representative longitudinal cohort in Japan, this retrospective analysis examined CLTI patients with tissue loss (ulcer and gangrene), between April 2012 and September 2020, identifying two distinct cohorts: those receiving non-revascularisation treatment and those undergoing revascularisation. The primary endpoint was amputation free survival, evaluated in both cohorts after applying propensity score matching. Results: Of the 3 160 CLTI patients with tissue loss, 559 received non-revascularisation treatment and 589 underwent revascularisation. The non-revascularisation treatment predominantly involved prostaglandin E1 injections (99.1%). After one to one propensity score matching, the revascularisation cohort (372 patients) exhibited a markedly enhanced amputation free survival rate compared with their non-revascularisation counterparts (amputation free survival rate at one year: 58.0% vs. 45.7%, p = .014). Subgroup analyses underscored the greater efficacy of revascularisation across multiple categories, including males (hazard ratio [HR] 0.59, 95% confidence interval [CI] 0.47 – 0.75), patients with diabetes mellitus (HR 0.67, 95% CI 0.50 – 0.89), and patients with severe wounds (HR 0.76, 95% CI 0.61 – 0.93). However, the analysis did not find differences between the revascularisation and non-revascularisation treatment groups among female patients (HR 1.06, 95% CI 0.78 – 1.45) and patients with non-severe wounds (HR 0.87, 95% CI 0.58 – 1.30). Conclusion: This regional Japanese cohort study revealed a potential enhancement in the amputation free survival rate post-revascularisation for CLTI patients with tissue loss compared with non-revascularisation treatment, except in female patients and patients with non-severe wounds. Additional studies are needed to further elucidate these results.

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Direct Comparison of Endurant Stent Graft System and Excluder Endoprosthesis using a Japanese Multicenter Registry

Hosokawa K., Fujimura N., Takahara M., Harada H., Uchida N., Fujii T., Shintani T., Watada S., Ono S., Sekimoto Y., Shimogawara T., Hayashi K., Obara H., Kitagawa Y.

Cardiovascular and Interventional Radiology 48 ( 11 ) 1562 - 1575 2025.11

ISSN 01741551

Objective: This retrospective cohort study aimed to emulate the ADVANCE trial population and directly compare the Endurant and Excluder using propensity score matching. Methods: Patients were included if endovascular aneurysm repair was performed for abdominal aortic aneurysm using either Endurant or Excluder at 10 hospitals in Japan between January 2012 and July 2022. Cases were selected according to the modified ADVANCE trial inclusion and exclusion criteria. To minimize selection bias and simulate a randomized controlled trial setting, propensity score matching was performed using patient and anatomical characteristics. The primary outcome measure was the proportion of patients with sac regression ≥ 5 mm at 1 year. The secondary outcome measures were rates of freedom from late complications, T1aEL, sac enlargement ≥ 5 mm, and overall survival. Outcomes were first analyzed in patients within the instructions for use (IFU) and then in all matched patients including outside IFU patients. Results: After matching, the within-IFU group included 124 pairs and the total cohort of 266 pairs. The primary outcome measures for Endurant and Excluder were met in 38.9% and 36.6% (p = 0.74) in the within-IFU group and 33.5% and 35.0% (p = 0.74) in the total cohort, respectively. No significant differences were observed in any secondary outcome measures. However, T2EL and use of additional proximal cuff were significantly more frequent for Excluder in both the within-IFU and total cohort. Furthermore, T1b and T5ELs occurred significantly more for Endurant in the total cohort. Conclusion: There were no significant differences in all clinical outcome measures between Endurant and Excluder. Levels of evidence: Level IV, multicenter retrospective cohort study.

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Current status of waitlist mortality and transplant probability for adult candidates with chronic end-stage liver disease for deceased donor liver transplantation under the Model for End-Stage Liver Disease score-based allocation policy in Japan

Takemura Y., Ueda Y., Takemura R., Mita J., Ashikari J., Kuramitsu K., Hasegawa Y., Kitago M., Obara H., Kitagawa Y., Ohdan H., Yokota H.

Journal of Gastroenterology 60 ( 11 ) 1414 - 1426 2025.11

ISSN 09441174

Background: In Japan’s deceased-donor liver transplantation (DDLT), a new allocation policy based on the Model for End-Stage Liver Disease (MELD) score, including the exceptional MELD system (Ex-MELD), which periodically assigns additional points to the basal MELD score, was implemented in May 2019. We assessed the current state of this system for adult candidates with chronic end-stage liver disease. Methods: Adult candidates (≥ 18 years) registered in the Japan Organ Transplant Network for DDLT as Status 2 cases (including chronic end-stage liver disease patients) between May 2019 and April 2023 were evaluated. We divided them into the MELD, Ex-MELD (major) [start 16 points, 2 points by 180 days], and Ex-MELD [hepatocellular carcinoma (HCC)] groups. Transplant probability and waitlist mortality rates were compared using competing risk analyses. The annual proportion of DDLT and the transition of median MELD at transplantation were also investigated. Results: There were 757 candidates in MELD,126 in Ex-MELD (major), and 99 in Ex-MELD (HCC) groups. The transplant probability rates were not significantly different (3-year transplant probability rate; MELD: 24.0% vs. Ex-MELD (major): 21.0% vs. Ex-MELD (HCC): 24.1%). The rate in the Ex-MELD (major) increased dramatically as the waiting period lengthened. The waitlist mortality rates in the Ex-MELD (major) group were significantly lower (3-year waitlist mortality rate; MELD: 50.5% vs. Ex-MELD (major): 25.0% vs. Ex-MELD (HCC): 57.0%). Although the proportion of Ex-MELD (major) increased yearly in the transplanted cases, the median MELD at transplantation did not change significantly. Conclusions: We clearly showed the current status of adult Status 2 candidates.

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Trends and Barriers in Liver Transplantation for Patients With Decompensated Cirrhosis: A 15-Year Single-Center Cohort at a Japanese Center

Hasegawa Y., Obara H., Ojiro K., Kitago M., Abe Y., Usui S., Taniki N., Nakamoto N., Kitagawa Y.

Transplantation Proceedings 57 ( 8 ) 1560 - 1564 2025.10

ISSN 00411345

Background and Aim: Liver transplantation is the only curative treatment for end-stage liver disease; however, access remains limited, particularly in Japan, where the severe shortage of deceased donors presents a major challenge. Research comprehensively assessing the full trajectory from referral to either transplantation or death remains scarce. We aimed to analyze long-term trends and propose potential strategies to improve access to liver transplantation in Japan. Patients and Methods: This study included 616 adult patients with decompensated liver cirrhosis referred for liver transplantation. Patients were divided into 3 periods to assess temporal trends: Period 1 (2009-2013), Period 2 (2014-2018), and Period 3 (2019-2023). The primary endpoint was the liver transplantation rate among referred patients. Patient demographics, liver disease etiology and severity, and donor type were analyzed. Results: The transplantation rate declined from 30.2% in Period 1 to 22.1% in Period 3, despite increases in follow-up rates and waitlist registrations. The availability of living donors significantly decreased over time, from 29.5% in Period 1 to 22.4% in Period 2 and 18.6% in Period 3. The rate of death without transplantation remained high (41.0%, 45.0%, and 40.0%, respectively). A higher MELD score at referral was an independent risk factor for both not undergoing transplantation and mortality among transplantation candidates. Conclusion: Over this 15-year period, the transplantation rate declined despite increases deceased donor registrations, resulting in persistently high waitlist mortality. Our findings suggest that expanding deceased donor pool and facilitating earlier referral of transplant candidates are essential to improving access to transplantation and patient outcomes in a Japanese transplant setting.

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Donor-Derived Cell-Free DNA Analyses in Small Intestine Transplantation: A Multicenter Prospective Observational Study in Japan

Yamada, Y; Kanamori, H; Shinoda, M; Kasahara, M; Sakamoto, S; Fukuda, A; Uchida, H; Matsuura, T; Kajihara, K; Hasegawa, Y; Obara, H; Kitagawa, Y; Inoue, I; Mitsunaga, S; Fujino, A

AMERICAN JOURNAL OF TRANSPLANTATION 25 ( 8 ) 2025.08

ISSN 1600-6135

Clinical outcomes in patients with chronic limb-threatening ischemia after femoropopliteal intervention with a drug-coated balloon or stenting

Kobayashi T., Takahara M., Fujimura N., Yamaoka T., Matsuda D., Okazaki T., Mochizuki S., Nagatomi S., Shingaki M., Endo M., Hosokawa K., Furuyama T., Shintani T., Sekimoto Y., Uchiyama H., Kyuragi R., Watada S., Morisaki K., Mitsuoka H., Kawai Y., Hayashi K., Shibata T., Kamei S., Obara H., Ichihashi S.

Journal of Vascular Surgery 82 ( 1 ) 164 - 172.e2 2025.07

ISSN 07415214

Objective: Endovascular treatment (EVT) for patients with an occlusive lesion of the femoropopliteal artery is performed worldwide due to its effectiveness. However, lesions in chronic limb-threatening ischemia (CLTI) are complex and a major concern in superficial femoral artery (SFA) EVT. Despite this, a detailed study of SFA EVT, and especially selection of the final device as a drug-coated balloon (DCB) or a stent, has not been performed in patients with CLTI. The aim of this stud was to compare the clinical outcomes of SFA EVT using a DCB or a stent in patients with CLTI. Methods: A multicenter retrospective observational study was performed at 21 Japanese centers. Comparisons were made between patients undergoing initial SFA EVT with a DCB or stenting after inverse probability of treatment weighting using the propensity score to control for potential confounding (patient demographics, comorbidities, medications, and procedural details). The primary outcome measure was major adverse limb events (MALE). We adopted cause-specific hazard models, using Fine and Gray's proportional hazards model in which death was treated as a competing risk. Secondary outcome measures were also evaluated: (1) technical success; (2) slow flow; (3) death within 30 days; (4) major adverse events within 30 days; (5) restenosis; (6) target lesion revascularization; (7) acute occlusion; (8) wound healing; (9) major amputation; and (10) all-cause mortality. Results: The study included 900 CLTI cases that underwent EVT with a DCB (n = 458) or stenting (n = 442) and had a median follow-up period of 17.5 months (interquartile range, 6.2-31.9 months). The DCB group had a lower risk of MALE than the stent group, with a hazard ratio of 0.68 (95% confidence interval, 0.52-0.89; P = .005). Subsequent analysis for the secondary outcome measures demonstrated that the DCB group had a higher prevalence of postprocedural slow flow and a lower incidence rate of acute occlusion (both P < .005 after Bonferroni correction). Conclusions: DCB angioplasty had a lower risk of MALE than stenting. These results suggest that a DCB might be more beneficial in initial SFA intervention in patients with CLTI.

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Detailed Analysis of Elective Endovascular Aneurysm Repair for Nonagenarians in Japanese Population Shows Comparable Mid-term Results With Octogenarians

Fujimura, N; Obara, H; Shimogawara, T; Ono, S; Hayashi, K; Watada, S; Fujii, T; Sekimoto, Y; Shintani, T; Harada, H; Uchida, N; Kitagawa, Y

JOURNAL OF VASCULAR SURGERY 81 ( 6 ) 2025.06

ISSN 0741-5214

Potential Impact of Screening Examinations on Prognosis of De Novo Malignancies in Adult Patients After Liver Transplantation

Uemura S., Hasegawa Y., Obara H., Kitago M., Yagi H., Abe Y., Hori S., Tanaka M., Nakano Y., Kitagawa Y.

Livers 5 ( 2 ) 2025.06

Background: De novo malignancies (DNMs) after liver transplantation (LT) are a major cause of long-term mortality. However, no definitive screening protocol has been established due to their diversity. This study aimed to evaluate DNM diagnosis methods, screening protocols, and prognoses. Methods: This retrospective study included 231 adult LT recipients from April 1997 to March 2021. Disease-specific survival (DSS) was analyzed to assess the impact of screening on prognosis. Most recipients underwent serum tests every three months, annual gastrointestinal endoscopy, and chest-abdominal CT as part of routine surveillance. Results: Twenty-five DNMs were diagnosed in 22 patients, with median age of 61 years (range, 23–72), of whom 13 (59.1%) were female. The duration from transplantation to DNM diagnosis of DNM was 88 months (range, 4–195). DNM was diagnosed as follows: seven patients (31.8%) through screening (screening group) and 15 patients (68.2%) by other means (non-screening group). Curative treatment was achieved in all of the patients diagnosed by screening, whereas it was possible in only 60.0% of patients diagnosed by other means (p = 0.026). DSS in the screening group was significantly longer than that in the non-screening group (p = 0.024). Conclusions: While screening was associated with earlier-stage diagnosis and improved outcomes in some patients, the overall efficacy of the protocol requires further validation in larger studies.

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A case of hepatic epithelioid hemangioendothelioma with features resembling those of acute-onset autoimmune hepatitis that was undiagnosed before liver transplantation

Usui S., Chu P.S., Hirano M., Hasegawa Y., Ueno A., Nomura R., Obara H., Kitagawa Y., Kanai T., Nakamoto N.

Clinical Journal of Gastroenterology 18 ( 3 ) 514 - 519 2025.06

ISSN 18657257

Hepatic epithelioid hemangioendothelioma (HEHE), which is extremely rare, is considered to have a malignant grade between that of hepatic hemangioma and that of hepatic hemangiosarcoma; however, some cases progress so quickly that they present with portal hypertension. We report the case of a woman with findings similar to those of acute-onset autoimmune hepatitis (AIH) that was not diagnosed before liver transplantation. The patient presented with jaundice and ascites. A hematological examination revealed negative tumor markers, high IgG levels, and negative hepatitis virus markers. Computed tomography findings of the liver showed map-like signs characteristic of acute-onset AIH. Despite some response, immunosuppressive drugs such as prednisolone, cyclosporine, and mycophenolate mofetil did not improve liver failure, and she underwent liver transplantation after 200 days of treatment. The explanted liver exhibited white areas that extended in a map-like manner and were occupied by fibrous stroma. Tumors with WWTR1-CAMTA1 gene fusion were recognized and diagnosed as HEHE. Although a histological examination is essential, a percutaneous liver biopsy could not be performed preoperatively because of the presence of ascites. Furthermore, the rarity of the disease, similarity of imaging findings with non-neoplastic patterns, and serological findings made it difficult to differentiate this case from acute-onset autoimmune hepatitis.

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Efficacy of aqueous olanexidine compared with alcohol-based chlorhexidine for surgical skin antisepsis regarding the incidence of surgical-site infections in clean-contaminated surgery: a randomized superiority trial

Takeuchi M., Obara H., Furube T., Kawakubo H., Kitago M., Okabayashi K., Fujisaki H., Aoyama J., Morimoto Y., Amemiya R., Sano J., Nakadai J., Goto R., Sato Y., Kitagawa Y.

British Journal of Surgery 112 ( 4 ) 2025.04

ISSN 00071323

Background: Surgical-site antisepsis is used to prevent surgical-site infections (SSIs). Although several guidelines have indicated the efficacy of antiseptics, such as chlorhexidine, povidone-iodine, and olanexidine, in reducing the SSI rate, an optimal recommendation is still not established. The aim of this study was to evaluate the efficacy of aqueous olanexidine compared with chlorhexidine-alcohol as the optimal antiseptic for preventing SSI in clean-contaminated surgery. Methods: This multicentre randomized trial for surgical skin antisepsis in clean-contaminated gastrointestinal and hepatobiliary-pancreatic surgeries in five hospitals evaluated the efficacy of olanexidine and chlorhexidine-alcohol. The primary endpoint was 30-day SSI. Secondary outcomes included the occurrence of SSI types, intervention-related toxicity, and reoperation caused by SSI. Results: Overall, 700 patients from five institutions underwent randomization; 347 received olanexidine and 345 received chlorhexidine-alcohol in the full analysis set. The 30-day SSI rate was 12.4% (43 of 347) in the olanexidine group and 13.6% (47 of 345) in the chlorhexidine-alcohol group (adjusted risk ratio (aRR) 0.911 (95% c.i. 0.625 to 1.327); P = 0.626). No significant differences were observed between the groups regarding the secondary outcomes, including the occurrence of superficial incisional SSI, deep incisional SSI, organ/space SSI, and reoperation caused by SSI. Overall adverse effects were seen in two patients (0.58%) in the olanexidine group and in three patients (0.87%) in the chlorhexidine-alcohol group (aRR 0.663 (95% c.i. 0.111 to 3.951)). Conclusion: Olanexidine did not significantly reduce the occurrence of overall SSI compared with chlorhexidine-alcohol. Nevertheless, these findings provide valuable insights for developing novel surgical SSI management protocols. Registration number: UMIN 000049712 (University Hospital Medical Information Network Clinical Trials Registry).

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Laparoscopic Donor Left Lateral Sectionectomy Using the Glissonean Pedicle Approach: Technical Details With Video

Hasegawa Y., Abe Y., Obara H., Yamada Y., Kitago M., Fujino A., Kitagawa Y.

Asian Journal of Endoscopic Surgery 18 ( 1 ) e70043 2025.01

ISSN 17585902

Introduction: Pure laparoscopy for living donor hepatectomy is gaining popularity due to its advantages. However, despite the long-standing application of laparoscopic donor left lateral sectionectomy, the dissection of the Glisson branch, portal vein, and biliary ducts, particularly those of the caudate lobe, remains insufficiently described. Although the Glissonean approach offers easy standardization for hilar dissection, clear landmarks for parenchymal transection, and reduces postoperative bile leakage, it has not been widely adopted in laparoscopic donor hepatectomy. Here, we introduce a modified Glissonean pedicle approach to address the movement restrictions in laparoscopic surgery. Surgical Technique: After liver mobilization, the Glisson of Spiegel lobe (G1L) was divided, followed by encircling the left Glissonean pedicle. A tape for the liver hanging maneuver was placed from the right edge of the left Glissonean pedicle, along the Arantius plate, to the left edge of the left hepatic vein. When the parenchymal transection was completed, the left hepatic vein was automatically taped. The left hepatic artery and left portal vein were exposed, and some branches of P1 were divided to lengthen for anastomosis. The left hepatic duct was taped by removing the left hepatic artery and left hepatic vein from the left Glissonean pedicle. The left hepatic duct was divided under intraoperative cholangiography. Next, the left hepatic artery, left portal vein, and left hepatic vein were sequentially divided, and the graft liver was retrieved. Discussion: Our Glissonean approach can help standardize donor left lateral sectionectomy, minimize the exposure of the left hepatic duct, and clarify B1 branch dissection.

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