RYOHEI TAKEI

Dr. RYOHEI TAKEI

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Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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16 August 2021 in Cancer Immunology, Immunotherapy
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Journal Article
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RTRYOHEI TAKEI
RYOHEI TAKEI
TMTomoharu Miyashita
Tomoharu Miyashita
STSatoshi Takada
Satoshi Takada
HTHidehiro Tajima
Hidehiro Tajima
INItasu Ninomiya
Itasu Ninomiya
Yasuhiko YamamotoYasuhiko Yamamoto
Yasuhiko Yamamoto
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.

Verified
Journal Article
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SMSAEKI MASAKAZU
SAEKI MASAKAZU
SMSeiichi Munesue
Seiichi Munesue
YHYuri Higashi
Yuri Higashi
AHAi Harashima
Ai Harashima
RTRYOHEI TAKEI
RYOHEI TAKEI
Yasuhiko YamamotoYasuhiko Yamamoto
Yasuhiko Yamamoto
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.

27 October 2018 in Journal of Medical Case Reports
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Journal Article
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IOIchiro Onishi
Ichiro Onishi
MKMasato Kayahara
Masato Kayahara
RTRYOHEI TAKEI
RYOHEI TAKEI
NMNaoki Makita
Naoki Makita
MMMasayoshi Munemoto
Masayoshi Munemoto
AKAtsuhiro Kawashima
Atsuhiro Kawashima
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.

10 February 2020 in American Journal of Case Reports
Verified
Journal Article
Closed access
RTRYOHEI TAKEI
RYOHEI TAKEI
KKKeiichiro Kanamoto
Keiichiro Kanamoto
YTYuta Tamaru
Yuta Tamaru
KNKoki Nojima
Koki Nojima
KMKazuyoshi Mitta
Kazuyoshi Mitta
MKMasato Kiriyama
Masato Kiriyama
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.

16 December 2024 in Asian Journal of Surgery
Verified
Journal Article
Open access
SNShinichi Nakanuma
Shinichi Nakanuma
TOTakahiro Ogi
Takahiro Ogi
HSHiroaki Sugita
Hiroaki Sugita
RGRyosuke Gabata
Ryosuke Gabata
TTTomokazu Tokoro
Tomokazu Tokoro
SYShintaro Yagi
Shintaro Yagi
In the current situation of an increasing older adult population with perihilar cholangiocarcinoma (PHCC), the benefits and risks of surgical treatment of PHCC in older people remain controversial. Portal vein embolization (PVE) is a useful preoperative procedure to improve hepatic reserve in the future remnant liver (FRL) and avoid postoperative liver failure after extended hepatectomy for PHCC. This study aimed to evaluate the influence of aging on PVE. We enrolled 25 patients who underwent right hepatectomy with percutaneous transhepatic PVE. Participants aged <70 years (n = 13) and ≥70 years (n = 12) were compared; correlation coefficients were evaluated using all cases. The FRL volume/total liver volume (FRLV/TLV) ratio and the indocyanine green (ICG) clearance rate (ICG-K) fraction of FRL to total liver (ICG-Krem) were analyzed as FRL hepatic reserves. FRLV/TLV ratio increased after PVE in <70 years and ≥70 years groups (p = 0.002 and p = 0.013, respectively). The change in ICG-K values from before to after PVE varied between both groups (p = 0.040). The ICG-Krem value after PVE increased only in the <70 years group (p = 0.009). A review of all cases showed a negative correlation between the change (after - before PVE) in the ICG-K and ICG-Krem values and age (r = -0.4827, p = 0.0145 and r = -0.4328, p = 0.0306, respectively). This study showed aging suppresses hepatic reserve improvement in the FRL, particularly in ICG clearance after PVE in PHCC cases.

6 February 2018 in American Journal of Case Reports
Verified
Journal Article
Open access
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RTRYOHEI TAKEI
RYOHEI TAKEI
IOIchiro Onishi
Ichiro Onishi
RZRyosuke Zaimoku
Ryosuke Zaimoku
NMNaoki Makita
Naoki Makita
YYYasumichi Yagi
Yasumichi Yagi
MKMasato Kayahara
Masato Kayahara
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...