Ryohei Takei
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Ryohei Takei has a total of 57 co-authors. Here are the top co-authors by number of shared publications:
- Shintaro Yagi
Department of Hepato-Biliary-Pancreatic Surgery and Transplantation, Kanazawa University, Kanazawa, Japan
5 shared publications Ryosuke Zaimoku
Department of Surgery, Kurobe City Hospital, Kurobe, Toyama 938-8502, Japan
3 shared publications- Satoshi Takada
Department of Hepato-Biliary-Pancreatic Surgery and Transplantation, Kanazawa University Hospital, Kanazawa, Ishikawa, Japan
3 shared publications - Shinichi Nakanuma
Department of Hepato-Biliary-Pancreatic Surgery and Transplantation, Kanazawa University, 13-1 Takara-Machi, Kanazawa, Ishikawa, 920-8641, Japan.
3 shared publications - Yasuhiko Yamamoto
Department of Biochemistry and Molecular Vascular Biology, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
3 shared publications Ai Harashima
Department of Biochemistry and Molecular Vascular Biology, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
2 shared publications
Latest Publications
- Open Access
- 14 April 2026
- Published by The Korean Association of Hepato-Biliary-Pancreatic Surgery in Annals of Hepato-Biliary-Pancreatic Surgery
- Vol. 30 (2) , 178-185
Laparoscopic versus open partial hepatectomy for hepatocellular carcinoma in F4 cirrhosis: A propensity score-matched study of perioperative safety
Hiroaki Sugita, Shinichi Nakanuma, Tomokazu Tokoro, Ryohei Takei, Mitsuyoshi Okazaki, Kaichiro Kato, Satoshi Takada, Isamu Makino, Shintaro Yagi. Ann Hepatobiliary Pancreat Surg -0001;0:. https://doi.org/10.14701/ahbps.26-046
- 14 April 2026
- Published by The Korean Association of Hepato-Biliary-Pancreatic Surgery in Annals of Hepato-Biliary-Pancreatic Surgery
- Vol. 30 (2) , 178-185
Open AccessLaparoscopic versus open partial hepatectomy for hepatocellular carcinoma in F4 cirrhosis: A propensity score-matched study of perioperative safety
Hiroaki Sugita, Shinichi Nakanuma, Tomokazu Tokoro, Ryohei Takei, Mitsuyoshi Okazaki, Kaichiro Kato, Satoshi Takada, Isamu Makino, Shintaro Yagi. Ann Hepatobiliary Pancreat Surg -0001;0:. https://doi.org/10.14701/ahbps.26-046
- Open Access
- 16 December 2024
- Published by Elsevier in Asian Journal of Surgery
- Vol. 48 (2) , 1010-1015
Impact of aging on hepatic reserve after preoperative portal vein embolization in hepatectomy for perihilar cholangiocarcinoma
- 16 December 2024
- Published by Elsevier in Asian Journal of Surgery
- Vol. 48 (2) , 1010-1015
Open AccessImpact of aging on hepatic reserve after preoperative portal vein embolization in hepatectomy for perihilar cholangiocarcinoma
- Open Access
- 15 November 2023
- Published by MDPI AG in International Journal of Molecular Sciences
- Vol. 24 (22) , 16328
Assaying ADAMTS13 Activity as a Potential Prognostic Biomarker for Sinusoidal Obstruction Syndrome in Mice
Sinusoidal obstruction syndrome (SOS) is a serious liver disorder that occurs after liver transplantation, hematopoietic stem cell transplantation, and the administration of anticancer drugs. Since SOS is a life-threatening condition that can progress to liver failure, early detection and prompt treatment are required for the survival of patients with this condition. In this study, female CD1 mice were divided into treatment and control groups after the induction of an SOS model using monocrotaline (MCT, 270 mg/kg body weight intraperitoneally). The mice were analyzed at 0, 12, 24, and 48 h after MCT administration, and blood and liver samples were collected for assays and histopathology tests. SOS was observed in the livers 12 h after MCT injection. In addition, immunohistochemical findings demonstrated CD42b-positive platelet aggregations, positive signals for von Willebrand factor (VWF), and a disintegrin-like metalloproteinase with thrombospondin type 1 motifs 13 (ADAMTS13) in the MCT-exposed liver sinusoid. Although ADAMTS13’s plasma concentrations peaked at 12 h, its enzyme activity continuously decreased by 75% at 48 h and, inversely and proportionally, concentrations in the VWF-A2 domain, in which the cleavage site of ADAMTS13 is located, increased after MCT injection. These findings suggest that the plasma concentration and activity of ADAMTS13 could be useful biomarkers for early detection and therapeutic intervention in patients with SOS.
- 15 November 2023
- Published by MDPI AG in International Journal of Molecular Sciences
- Vol. 24 (22) , 16328
Open AccessAssaying ADAMTS13 Activity as a Potential Prognostic Biomarker for Sinusoidal Obstruction Syndrome in Mice
Sinusoidal obstruction syndrome (SOS) is a serious liver disorder that occurs after liver transplantation, hematopoietic stem cell transplantation, and the administration of anticancer drugs. Since SOS is a life-threatening condition that can progress to liver failure, early detection and prompt treatment are required for the survival of patients with this condition. In this study, female CD1 mice were divided into treatment and control groups after the induction of an SOS model using monocrotaline (MCT, 270 mg/kg body weight intraperitoneally). The mice were analyzed at 0, 12, 24, and 48 h after MCT administration, and blood and liver samples were collected for assays and histopathology tests. SOS was observed in the livers 12 h after MCT injection. In addition, immunohistochemical findings demonstrated CD42b-positive platelet aggregations, positive signals for von Willebrand factor (VWF), and a disintegrin-like metalloproteinase with thrombospondin type 1 motifs 13 (ADAMTS13) in the MCT-exposed liver sinusoid. Although ADAMTS13’s plasma concentrations peaked at 12 h, its enzyme activity continuously decreased by 75% at 48 h and, inversely and proportionally, concentrations in the VWF-A2 domain, in which the cleavage site of ADAMTS13 is located, increased after MCT injection. These findings suggest that the plasma concentration and activity of ADAMTS13 could be useful biomarkers for early detection and therapeutic intervention in patients with SOS.
- Open Access
- 7 September 2021
- Published by Springer Nature in Cancer Immunology, Immunotherapy
- Vol. 71 (4) , 791-793
Correction to: Dynamic switch of immunity and antitumor effects of metformin in rat spontaneous esophageal carcinogenesis
- 7 September 2021
- Published by Springer Nature in Cancer Immunology, Immunotherapy
- Vol. 71 (4) , 791-793
Open AccessCorrection to: Dynamic switch of immunity and antitumor effects of metformin in rat spontaneous esophageal carcinogenesis
- Open Access
- 16 August 2021
- Published by Springer Nature in Cancer Immunology, Immunotherapy
- Vol. 71 (4) , 777-789
Dynamic switch of immunity and antitumor effects of metformin in rat spontaneous esophageal carcinogenesis
Chronic inflammation contributes to tumor development by creating a local microenvironment that facilitates neoplastic transformation and potentiates the progression of cancer. Esophageal cancer (EC) is an inflammation-associated malignancy with a poor prognosis. The nature of the switch between chronic inflammation of the esophagus and EC-related immunological changes remains unclear. Here, we examined the dynamic alterations of immune cells at different stages of chronic esophagitis, Barrett’s esophagus (BE) and EC using an esophageal spontaneous carcinogenesis rat model. We also investigated the anticancer effects of metformin. To stimulate EC carcinogenesis, chronic gastroduodenal reflux esophagitis via esophagojejunostomy was induced in 120 rats in metformin-treated and non-treated (control) groups. After 40 weeks, BE and EC developed in 96.7% and 63.3% of the control group, and in 66.7% and 23.3% of the metformin-treated group, respectively. Flow cytometric analysis demonstrated that the balance of M1/M2-polarized or phospho-Stat3-positive macrophages, regulatory T, cytotoxic T, natural killer (NK), NK T cells, and Th17 T cells was dynamically changed at each stage of the disease and were resolved by metformin treatment. These findings clarify the immunity in esophageal carcinogenesis and suggest that metformin could suppress this disease by improving the immunosuppressive tumor microenvironment and immune evasion.
- 16 August 2021
- Published by Springer Nature in Cancer Immunology, Immunotherapy
- Vol. 71 (4) , 777-789
Open AccessDynamic switch of immunity and antitumor effects of metformin in rat spontaneous esophageal carcinogenesis
Chronic inflammation contributes to tumor development by creating a local microenvironment that facilitates neoplastic transformation and potentiates the progression of cancer. Esophageal cancer (EC) is an inflammation-associated malignancy with a poor prognosis. The nature of the switch between chronic inflammation of the esophagus and EC-related immunological changes remains unclear. Here, we examined the dynamic alterations of immune cells at different stages of chronic esophagitis, Barrett’s esophagus (BE) and EC using an esophageal spontaneous carcinogenesis rat model. We also investigated the anticancer effects of metformin. To stimulate EC carcinogenesis, chronic gastroduodenal reflux esophagitis via esophagojejunostomy was induced in 120 rats in metformin-treated and non-treated (control) groups. After 40 weeks, BE and EC developed in 96.7% and 63.3% of the control group, and in 66.7% and 23.3% of the metformin-treated group, respectively. Flow cytometric analysis demonstrated that the balance of M1/M2-polarized or phospho-Stat3-positive macrophages, regulatory T, cytotoxic T, natural killer (NK), NK T cells, and Th17 T cells was dynamically changed at each stage of the disease and were resolved by metformin treatment. These findings clarify the immunity in esophageal carcinogenesis and suggest that metformin could suppress this disease by improving the immunosuppressive tumor microenvironment and immune evasion.
- Open Access
- 1 October 2020
- Published by Oxford University Press (OUP) in Journal of Surgical Case Reports
- Vol. 2020 (10)
Pedicled jejunal flap reconstruction for partial duodenectomy: a report of two cases
Conventional jejunal reconstruction procedures for large duodenal defects include jejunal serosal patch repair and duodenojejunostomy and have some risks of postoperative complications. The pedicled jejunal flap is used for reconstruction following laryngopharyngectomy, esophagectomy and other gastrointestinal surgeries. We report two cases of successful closure of duodenal defects after partial duodenectomies by pedicled jejunal flap reconstruction. Case 1: A 72-year-old man was diagnosed with gastrointestinal stromal tumor by esophagogastroduodenoscopy (EGD), endoscopic ultrasound-guided fine needle aspiration biopsy and computed tomography (CT). Case 2: A 63-year-old woman was diagnosed with early duodenal cancer using EGD and CT. Partial duodenectomy and pedicled jejunal flap reconstruction were performed in both patients. A part of the jejunum was formed into a pedicled flap to fit the duodenal defect and duodenojejunal anastomosis was performed. The patients did not report any postoperative gastrointestinal symptoms or abnormal findings during follow-up EGD or upper gastrointestinal radiography.
- 1 October 2020
- Published by Oxford University Press (OUP) in Journal of Surgical Case Reports
- Vol. 2020 (10)
Open AccessPedicled jejunal flap reconstruction for partial duodenectomy: a report of two cases
Conventional jejunal reconstruction procedures for large duodenal defects include jejunal serosal patch repair and duodenojejunostomy and have some risks of postoperative complications. The pedicled jejunal flap is used for reconstruction following laryngopharyngectomy, esophagectomy and other gastrointestinal surgeries. We report two cases of successful closure of duodenal defects after partial duodenectomies by pedicled jejunal flap reconstruction. Case 1: A 72-year-old man was diagnosed with gastrointestinal stromal tumor by esophagogastroduodenoscopy (EGD), endoscopic ultrasound-guided fine needle aspiration biopsy and computed tomography (CT). Case 2: A 63-year-old woman was diagnosed with early duodenal cancer using EGD and CT. Partial duodenectomy and pedicled jejunal flap reconstruction were performed in both patients. A part of the jejunum was formed into a pedicled flap to fit the duodenal defect and duodenojejunal anastomosis was performed. The patients did not report any postoperative gastrointestinal symptoms or abnormal findings during follow-up EGD or upper gastrointestinal radiography.
- 10 February 2020
- Published by International Scientific Information, Inc. in American Journal of Case Reports
- Vol. 21, e922405-e922405-5
A Case of Strangulation Ileus Due to a Low-Grade Appendiceal Mucinous Neoplasm
BACKGROUND Strangulation ileus is caused by external obstruction to the small bowel, which results in ischemia and loss of bowel peristalsis. Low-grade appendiceal mucinous neoplasm (LAMN) is a low-grade adenocarcinoma that arises in the appendix. LAMN is usually asymptomatic but can present with appendiceal rupture and pseudomyxoma peritonei (PMP). This report is of a rare presentation of LAMN with strangulation ileus in a 92-year-old man. CASE REPORT A 92-year-old man was admitted to the emergency room with sudden onset of lower abdominal pain and abdominal distension. Laboratory investigations showed a leukocytosis with a white blood cell (WBC) count of 14.6×10³/μL with 85.5% neutrophils, blood urea nitrogen (BUN) of 26.6 mg/dL, and serum creatinine of 2.6 mg/dL, consistent with acute renal failure. Arterial blood gas analysis showed lactic acidosis (pH of 7.11) with a base excess of -20.8 mmol/L and lactate of 13.7 mmol/L. Abdominal computed tomography (CT) showed ascites and a dilated obstructed closed loop of the distal ileum associated with an external mass (3.9×2.8 cm). An initial diagnosis was of strangulation ileus due to Meckel's diverticulum. Emergency ileocecal resection was performed. Histopathology showed a low-grade mucinous tumor arising from the mucosa of the appendix, consistent with LAMN. At a 13-month follow-up, the patient was well with no tumor recurrence. CONCLUSIONS This report is of a rare case of LAMN that presented as a surgical emergency with strangulation ileus.
- 10 February 2020
- Published by International Scientific Information, Inc. in American Journal of Case Reports
- Vol. 21, e922405-e922405-5
A Case of Strangulation Ileus Due to a Low-Grade Appendiceal Mucinous Neoplasm
BACKGROUND Strangulation ileus is caused by external obstruction to the small bowel, which results in ischemia and loss of bowel peristalsis. Low-grade appendiceal mucinous neoplasm (LAMN) is a low-grade adenocarcinoma that arises in the appendix. LAMN is usually asymptomatic but can present with appendiceal rupture and pseudomyxoma peritonei (PMP). This report is of a rare presentation of LAMN with strangulation ileus in a 92-year-old man. CASE REPORT A 92-year-old man was admitted to the emergency room with sudden onset of lower abdominal pain and abdominal distension. Laboratory investigations showed a leukocytosis with a white blood cell (WBC) count of 14.6×10³/μL with 85.5% neutrophils, blood urea nitrogen (BUN) of 26.6 mg/dL, and serum creatinine of 2.6 mg/dL, consistent with acute renal failure. Arterial blood gas analysis showed lactic acidosis (pH of 7.11) with a base excess of -20.8 mmol/L and lactate of 13.7 mmol/L. Abdominal computed tomography (CT) showed ascites and a dilated obstructed closed loop of the distal ileum associated with an external mass (3.9×2.8 cm). An initial diagnosis was of strangulation ileus due to Meckel's diverticulum. Emergency ileocecal resection was performed. Histopathology showed a low-grade mucinous tumor arising from the mucosa of the appendix, consistent with LAMN. At a 13-month follow-up, the patient was well with no tumor recurrence. CONCLUSIONS This report is of a rare case of LAMN that presented as a surgical emergency with strangulation ileus.
- Open Access
- 27 October 2018
- Published by Springer Nature in Journal of Medical Case Reports
- Vol. 12 (1) , 314
Recurrent biliary dissemination of colon cancer liver metastasis: a case report
Most colorectal cancer liver metastases form nodules within the hepatic parenchyma, and hepatectomy is the only radical treatment for synchronous metastases. There is concern about intrabiliary tumor growth which may affect the surgical margin, resulting in local recurrence after hepatectomy for colorectal cancer liver metastasis; however, there has been no report of the dissemination in the bile duct after hepatectomy. Here, we report an unusual case of biliary dissemination of colorectal cancer that caused recurrent intrabiliary growth after hepatectomy, and discuss the management of intrabiliary metastasis of colorectal cancer. A 69-year-old Japanese man underwent treatment for liver dysfunctions 3 years after aortic valve replacement. Computed tomography revealed an enhanced tumor within the hilar bile duct and dilatation of the left hepatic duct, typical of hilar cholangiocarcinoma. Endoscopic retrograde cholangiopancreatography revealed tumor shadow in his bile duct, and the cytology confirmed malignant cells in the bile. We performed extended left hepatectomy with bile duct resection; his postoperative course remained good without acute complications. After 3 months postoperatively, he was readmitted for subacute cholangitis and obstructive jaundice. Immediately, percutaneous transhepatic cholangiography drainage was performed, followed by cholangiography that exhibited intrabiliary tumor growth in the remnant liver. On immunohistochemical examination, tumor cells were positive for cytokeratin 20 and CDX2 but negative for cytokeratin 7. Then, computed tomography revealed an enhanced tumor-like lesion at the descending colon. After 3 months, left hemicolectomy was performed. Meanwhile, the percutaneous transhepatic cholangiography drainage fluid turned bloody, which was considered to be bleeding from a residual bile duct tumor. Accordingly, radiotherapy was initiated to prevent tumor bleeding around the hilar bile duct, but, unfortunately, the effects were short-lived, and cholangitis rebooted after 1 month leading to our patient’s death due to septic liver failure. Autopsy revealed a remnant tumor in the bile duct, but no noticeable nodular metastasis was observed, except for a single small metastasis in the lower lobe of the left lung. The intrabiliary growth of metastatic colorectal cancer mimics cholangiocarcinoma occasionally. To date, as the effect of chemotherapy or radiotherapy remains uncertain, the complete resection of a bile duct tumor is the only method which could result in a better prognosis.
- 27 October 2018
- Published by Springer Nature in Journal of Medical Case Reports
- Vol. 12 (1) , 314
Open AccessRecurrent biliary dissemination of colon cancer liver metastasis: a case report
Most colorectal cancer liver metastases form nodules within the hepatic parenchyma, and hepatectomy is the only radical treatment for synchronous metastases. There is concern about intrabiliary tumor growth which may affect the surgical margin, resulting in local recurrence after hepatectomy for colorectal cancer liver metastasis; however, there has been no report of the dissemination in the bile duct after hepatectomy. Here, we report an unusual case of biliary dissemination of colorectal cancer that caused recurrent intrabiliary growth after hepatectomy, and discuss the management of intrabiliary metastasis of colorectal cancer. A 69-year-old Japanese man underwent treatment for liver dysfunctions 3 years after aortic valve replacement. Computed tomography revealed an enhanced tumor within the hilar bile duct and dilatation of the left hepatic duct, typical of hilar cholangiocarcinoma. Endoscopic retrograde cholangiopancreatography revealed tumor shadow in his bile duct, and the cytology confirmed malignant cells in the bile. We performed extended left hepatectomy with bile duct resection; his postoperative course remained good without acute complications. After 3 months postoperatively, he was readmitted for subacute cholangitis and obstructive jaundice. Immediately, percutaneous transhepatic cholangiography drainage was performed, followed by cholangiography that exhibited intrabiliary tumor growth in the remnant liver. On immunohistochemical examination, tumor cells were positive for cytokeratin 20 and CDX2 but negative for cytokeratin 7. Then, computed tomography revealed an enhanced tumor-like lesion at the descending colon. After 3 months, left hemicolectomy was performed. Meanwhile, the percutaneous transhepatic cholangiography drainage fluid turned bloody, which was considered to be bleeding from a residual bile duct tumor. Accordingly, radiotherapy was initiated to prevent tumor bleeding around the hilar bile duct, but, unfortunately, the effects were short-lived, and cholangitis rebooted after 1 month leading to our patient’s death due to septic liver failure. Autopsy revealed a remnant tumor in the bile duct, but no noticeable nodular metastasis was observed, except for a single small metastasis in the lower lobe of the left lung. The intrabiliary growth of metastatic colorectal cancer mimics cholangiocarcinoma occasionally. To date, as the effect of chemotherapy or radiotherapy remains uncertain, the complete resection of a bile duct tumor is the only method which could result in a better prognosis.
- Open Access
- 6 February 2018
- Published by International Scientific Information, Inc. in American Journal of Case Reports
- Vol. 19, 133-136
Adenocarcinoma in a Blind Loop of the Ileum 53 Years After an Ileotransversostomy Procedure
BACKGROUND:Primary small bowel cancer is a rare malignancy; the common histopathological types are carcinoid and adenocarcinoma. Inflammatory bowel diseases and familial adenomatous polyposis are known risk factors for small bowel cancer. Additionall...
- 6 February 2018
- Published by International Scientific Information, Inc. in American Journal of Case Reports
- Vol. 19, 133-136
Open AccessAdenocarcinoma in a Blind Loop of the Ileum 53 Years After an Ileotransversostomy Procedure
BACKGROUND:Primary small bowel cancer is a rare malignancy; the common histopathological types are carcinoid and adenocarcinoma. Inflammatory bowel diseases and familial adenomatous polyposis are known risk factors for small bowel cancer. Additionall...