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Dive into the research topics where Kenichiro Okimoto is active.

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Featured researches published by Kenichiro Okimoto.


Digestive Endoscopy | 2017

Vonoprazan is superior to proton pump inhibitors in healing artificial ulcers of the stomach post-endoscopic submucosal dissection: A propensity score-matching analysis.

Daisuke Maruoka; Makoto Arai; Shingo Kasamatsu; Hideaki Ishigami; Takashi Taida; Kenichiro Okimoto; Keiko Saito; Tomoaki Matsumura; Tomoo Nakagawa; Tatsuro Katsuno; Osamu Yokosuka

Proton pump inhibitors (PPI) are effective at healing artificial ulcers after endoscopic submucosal dissection (ESD) for gastric neoplasms; however, the efficacy of vonoprazan is not completely understood. The aim of the present study was to determine the healing effect of vonoprazan on artificial ulcers post‐gastric ESD relative to PPI.


Digestive Endoscopy | 2014

Predictive factor of re‐bleeding after negative capsule endoscopy for obscure gastrointestinal bleeding: Over 1‐year follow‐up study

Tomoaki Matsumura; Makoto Arai; Keiko Saito; Kenichiro Okimoto; Masaya Saito; Shoko Minemura; Arata Oyamada; Daisuke Maruoka; Tomoo Nakagawa; Hirotsugu Watabe; Tatsuro Katsuno; Osamu Yokosuka

Capsule endoscopy (CE) is now widely accepted as a first‐line diagnostic modality for obscure gastrointestinal bleeding (OGIB), with a high diagnostic yield compared to other modalities. However, even after negative CE examination, re‐bleeding is often known to occur. The aim of the present study was to identify predictive factors of re‐bleeding after negative CE, and to clarify the clinical utility of double‐balloon enteroscopy (DBE) after negative CE for OGIB.


Digestive Endoscopy | 2017

Heparin-bridging therapy is associated with a high risk of post-polypectomy bleeding regardless of polyp size.

Hideaki Ishigami; Makoto Arai; Tomoaki Matsumura; Daisuke Maruoka; Shoko Minemura; Kenichiro Okimoto; Shingo Kasamatsu; Keiko Saito; Tomoo Nakagawa; Tatsuro Katsuno; Osamu Yokosuka

Evidence regarding safety and efficacy of heparin‐bridging therapy for colonoscopic polypectomy remains scarce. The aim of the present study was to evaluate the risk of post‐polypectomy bleeding (PPB) in patients receiving heparin‐bridging therapy.


Clinical and translational gastroenterology | 2017

Endoscopy-Guided Evaluation of Duodenal Mucosal Permeability in Functional Dyspepsia

Hideaki Ishigami; Tomoaki Matsumura; Shingo Kasamatsu; Shinsaku Hamanaka; Takashi Taida; Kenichiro Okimoto; Keiko Saito; Shoko Minemura; Daisuke Maruoka; Tomoo Nakagawa; Tatsuro Katsuno; Mai Fujie; Makoto Arai

OBJECTIVES: The pathophysiology of functional dyspepsia (FD) is not fully understood. Impaired duodenal mucosal integrity characterized by increased mucosal permeability and/or low‐grade inflammation was reported as potentially important etiologies. We aimed to determine the utility of a recently developed simple catheterization method to measure mucosal admittance (MA), the inverse of mucosal impedance, for evaluation of duodenal mucosal permeability in patients with FD. METHODS: We conducted two prospective studies. In the first study, duodenal MA of 23 subjects was determined by catheterization during upper endoscopy, and transepithelial electrical resistance (TEER) of duodenal biopsy samples in Ussing chambers was measured to assess the correlation between MA and TEER. In the second study, duodenal MA of 21 patients with FD fulfilling the Rome III criteria was compared with that of 23 healthy subjects. RESULTS: The mean MA and TEER values were 367.5±134.7 and 24.5±3.7 Ω cm2, respectively. There was a significant negative correlation between MA and TEER (r=−0.67, P=0.0004, Pearsons correlation coefficient). The mean MA in patients with FD was significantly higher than that in healthy subjects (455.7±137.3 vs. 352.1±66.9, P=0.002, unpaired t‐test). No procedure‐related complications were present. CONCLUSIONS: We demonstrated the presence of increased duodenal mucosal permeability in patients with FD by MA measurement using a simple catheterization method during upper endoscopy.


International Journal of Colorectal Disease | 2016

A randomized controlled trial comparing water exchange and air insufflation during colonoscopy without sedation.

Makoto Arai; Kenichiro Okimoto; Hideaki Ishigami; Takashi Taida; Arata Oyamada; Shoko Minemura; Keiko Saito; Masaru Tsuboi; Daisuke Maruoka; Tomoaki Matsumura; Tomoo Nakagawa; Tatsuro Katsuno; Kanae Mitsuhashi; Yuki Nakagawa; Kazuya Yamaguchi; Osamu Yokosuka

ObjectivesPrevious studies have shown that water exchange is superior to air insufflation in attenuating insertion pain during colonoscopy. We conducted a randomized controlled trial with head-to-head comparison of these methods to assess their effectiveness in colonoscopy without sedation.MethodsA total of 447 outpatients were randomized to either water exchange (WE) or the standard air (CO2) insufflation (AI). The primary outcome was the improvement of patient intraprocedural pain (pain score), evaluated using a questionnaire (scores 1 to 5).ResultsAfter exclusion of 44 patients from further analysis, 403 patients were analyzed. There was no difference in clinical background between the WE and AI groups. Patients in the WE group reported less intraprocedural pain than those in the AI group (2.17 ± 1.06 vs. 2.42 ± 1.03; unpaired t test, p = 0.021). We divided the cases into two groups, more or less painful colonoscopy, based on age, body mass index, use of anti-peristaltic drugs or not, and physician’s experience. In less painful colonoscopy, the WE method could reduce pain effectively but its effect was limited in the more painful group.ConclusionWE is superior to AI for attenuating insertion pain during colonoscopy without sedation, but its efficacy is limited in more painful endoscopy.


Scandinavian Journal of Gastroenterology | 2015

Sporadic nonampullary duodenal adenoma/carcinoma is associated with not only colon adenoma/carcinoma but also gastric cancer: association of location of duodenal lesions with comorbid diseases.

Daisuke Maruoka; Makoto Arai; Hideaki Ishigami; Kenichiro Okimoto; Keiko Saito; Shoko Minemura; Tomoaki Matsumura; Tomoo Nakagawa; Tatsuro Katsuno; Osamu Yokosuka

Abstract Background. It is well known that in patients with sporadic nonampullary duodenal adenoma/carcinoma (SNADA) with no polyposis syndrome, including familial adenomataous polyposis, the rates of colorectal adenoma/carcinoma are high. However, the prevalence rates of other tumor types, for example, gastric cancer, in SNADA patients remain unknown. In this study, we aimed to analyze the prevalence rate of comorbid diseases in SNADA patients. Methods. We retrospectively analyzed 78 patients with SNADA treated by endoscopic resection between May 2005 and September 2014 at our institution. Results. Overall, 51 of the 78 (65.4%) SNADA patients had comorbid colorectal adenoma/carcinoma. Further, 10 of the 78 (12.8%) SNADA patients had comorbid gastric cancer, and all of them were positive for Helicobacter pylori infection. SNADA lesions were located significantly more frequently at the oral side of the major papilla in patients with H. pylori infection than in those without H. pylori infection (27 of 36 [75.0%] vs. 19 of 42 [45.2%], p = 0.008, chi-square test). In contrast, SNADA lesions were located significantly more frequently at the anal side of the major papilla in patients with colorectal adenoma/carcinoma than in those without colorectal adenoma/carcinoma (27 of 51 [52.9%] vs. 5 of 27 [18.5%], p = 0.003, chi-square test). Conclusion. SNADA patients showed comorbidity with not only colorectal adenoma/carcinoma but also gastric cancer. H. pylori infection is known to cause gastric cancer and may influence tumorigenesis of SNADA lesions at the oral side of the major papilla.


Oncotarget | 2017

Mutational analysis of multiple lung cancers: Discrimination between primary and metastatic lung cancers by genomic profile

Taichiro Goto; Yosuke Hirotsu; Hitoshi Mochizuki; Takahiro Nakagomi; Daichi Shikata; Yujiro Yokoyama; Toshio Oyama; Kenji Amemiya; Kenichiro Okimoto; Masao Omata

In cases of multiple lung cancers, individual tumors may represent either a primary lung cancer or both primary and metastatic lung cancers. Treatment selection varies depending on such features, and this discrimination is critically important in predicting prognosis. The present study was undertaken to determine the efficacy and validity of mutation analysis as a means of determining whether multiple lung cancers are primary or metastatic in nature. The study involved 12 patients who underwent surgery in our department for multiple lung cancers between July 2014 and March 2016. Tumor cells were collected from formalin-fixed paraffin-embedded tissues of the primary lesions by using laser capture microdissection, and targeted sequencing of 53 lung cancer-related genes was performed. In surgically treated patients with multiple lung cancers, the driver mutation profile differed among the individual tumors. Meanwhile, in a case of a solitary lung tumor that appeared after surgery for double primary lung cancers, gene mutation analysis using a bronchoscopic biopsy sample revealed a gene mutation profile consistent with the surgically resected specimen, thus demonstrating that the tumor in this case was metastatic. In cases of multiple lung cancers, the comparison of driver mutation profiles clarifies the clonal origin of the tumors and enables discrimination between primary and metastatic tumors.


European Journal of Radiology | 2017

Mesenteric findings of CT enterography are well correlated with the endoscopic severity of Crohn’s disease

Takehiro Sakurai; Tatsuro Katsuno; Keiko Saito; Sayuri Yoshihama; Tomoo Nakagawa; Hirotaka Koseki; Takashi Taida; Hideaki Ishigami; Kenichiro Okimoto; Daisuke Maruoka; Tomoaki Matsumura; Makoto Arai; Osamu Yokosuka

BACKGROUND Maintenance of mucosal healing is a primary goal when treating Crohns disease (CD). Endoscopy is the most precise method for the assessment of mucosal healing, but is considered overly invasive for patients with CD. In contrast, CT enterography (CTE) is less invasive, but little is known about the correlation between mucosal status and CTE parameters. METHODS We recruited CD patients who underwent CTE and double balloon endoscopy (DBE) on the same day at our hospital between 2012 and 2014. CTE parameters evaluated included bowel-wall thickening, mural hyperenhancement, mural stratification (target sign), submucosal fat deposition, mesenteric hypervascularity (comb sign), increased fat density, mesenteric fibrofatty proliferation, enlarged mesenteric lymph nodes, and stenosis/sacculation. Endoscopic findings were evaluated using the Simple Endoscopic Score for Crohns Disease (SES-CD). CTE parameters that were predictive of higher values in the SES-CD were extracted statistically. RESULTS Forty-one patients were recruited, from which 191 intestinal segments were evaluated. Spearmans rank correlation coefficients showed that the majority of CTE values exhibited mild to moderate correlations with SES-CD values. Notably, multiple ordinal logistic regression analysis demonstrated that CTE findings obtained from the mesenteric area, such as mesenteric hypervascularity (comb sign) and enlarged mesenteric lymph nodes, were more critical predictors of endoscopic mucosal ulceration than those obtained from the bowel wall. CONCLUSIONS This study was the first of its kind to assess correlations between CTE values and SES-CD values. Mesenteric findings of CTE, rather than mural findings, were highly correlated with the endoscopically evaluated severity of ulceration.


Endoscopy | 2017

Cold polypectomy for duodenal adenomas: a prospective clinical trial

Daisuke Maruoka; Tomoaki Matsumura; Shingo Kasamatsu; Hideaki Ishigami; Takashi Taida; Kenichiro Okimoto; Tomoo Nakagawa; Tatsuro Katsuno; Makoto Arai

Background and study aims Endoscopic resection is effective in treating nonampullary duodenal adenomas but has a high incidence of complications. Cold polypectomy, including cold forceps polypectomy (CFP) and cold snare polypectomy (CSP), is safe and effective in treating colorectal polyps. However, its utility in sporadic nonampullary duodenal adenomas has not been investigated. The purpose of this prospective study was to examine the safety and efficacy of cold polypectomy for sporadic nonampullary duodenal adenomas. Patients and methods Between March 2015 and June 2016, patients who were endoscopically diagnosed with sporadic nonampullary duodenal adenomas up to 6 mm underwent cold polypectomy. Patients with pathologically confirmed adenomas underwent endoscopic biopsy 3 months after resection. The main outcomes of interest were incomplete resection and complications. Results Overall, 39 lesions in 30 patients were removed via cold polypectomy (CFP, 9 lesions in 8 patients; CSP, 30 lesions in 22 patients). Seven of 9 (77.8 %) and 29 of 30 (96.7 %) lesions were removed en bloc via CFP and CSP, respectively. Pathologically, 34 of the 39 lesions (87.2 %) were confirmed as adenomas, and their mean size was 3.9 ± 1.2 mm (range 2 - 6 mm). Of the 34 adenomas, 20 (58.8 %) were R0 resection lesions, of which 3 of 9 (33.3 %) and 17 of 25 (68.0 %) had undergone CFP and CSP, respectively. No delayed bleeding or intraprocedural/delayed perforation was observed. All 30 patients with the 34 pathologically confirmed adenomas underwent upper gastrointestinal endoscopy 3 months after cold polypectomy, and no morphological or pathological recurrence was identified. Conclusions In this small study, cold polypectomy appeared to be safe and effective in treating diminutive and small sporadic nonampullary duodenal adenomas.(Clinical trial registration number: UMIN000016829).


World Journal of Gastroenterology | 2014

Two-week treatment with proton pump inhibitor is sufficient for healing post endoscopic submucosal dissection ulcers

Makoto Arai; Tomoaki Matsumura; Kenichiro Okimoto; Arata Oyamada; Keiko Saito; Shoko Minemura; Daisuke Maruoka; Takeshi Tanaka; Tomoo Nakagawa; Tatsuro Katsuno; Osamu Yokosuka

AIM To investigate the optimum period of treatment for post endoscopic submucosal dissection (ESD) ulcers. METHODS Patients who underwent ESD for gastric cancer were randomized to two groups and treated with esomeprazole 20 mg per day for 4 wk (4W group) or 2 wk (2W group). At 4 wk after ESD, we measured the size of the artificial ulcers by endoscopy and determined the ulcer healing rate, compared with the size of the ESD specimens. This randomized controlled trial study was approved by our ethics committee and registered in the UMIN Clinical Trial Registry. RESULTS A total of 60 consecutive patients were included in the study. All patients received rebamipide 300 mg per day for 4 wk. One patient in 2W group who showed bleeding within two weeks and received endoscopic treatment was excluded from further analysis. The numbers of patients with ulcers in the healing/scar stage in the 2W and 4W groups at 4 wk after ESD were 20/6 and 28/5, respectively, with no significant difference. The ulcer healing rate in the 2W and 4W groups were 96.1% [95% confidence interval (CI): 94.6%-97.55] vs 94.8% (95%CI: 92.6%-97.1%), respectively, with no statistical difference (UMIN000006951). CONCLUSION Two-wk treatment with a proton pump inhibitor is as effective as four-week treatment for healing post ESD ulcers.

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