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Dive into the research topics where Kaoru Yokoyama is active.

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Featured researches published by Kaoru Yokoyama.


Digestion | 2011

Submucosal Fibrosis and Basic-Fibroblast Growth Factor-Positive Neutrophils Correlate with Colonic Stenosis in Cases of Ulcerative Colitis

Masaru Yamagata; Tetuo Mikami; Tomoko Tsuruta; Kaoru Yokoyama; Miwa Sada; Kiyonori Kobayashi; Tomoe Katsumata; Wasaburou Koizumi; Katsunori Saigenji; Isao Okayasu

Background and Aims: The frequency of benign stenosis in ulcerative colitis (UC) is low, reported as being 3.2–11.2%, with fibrosis in the submucosa or deeper pointed out as one of the causes. The aim of the present study was to assess stenosis in UC cases using immunostaining and to analyze differences between stenotic and nonstenotic cases, focusing on basic-fibroblast growth factor (b-FGF) expression and myofibroblasts. Methods: Totals of 9 stenotic and 17 nonstenotic UC cases were histopathologically examined and immunohistochemically stained for b-FGF, α-smooth muscle actin (α-SMA), CD34, CD68 and IL-6. To identify b-FGF-positive cells, double immunostaining for b-FGF and myeloperoxidase or CD68 was performed. Results: In addition to submucosal fibrosis, a significant increase of b-FGF-positive inflammatory cells and myofibroblasts was observed in stenotic portions. Most b-FGF-positive cells were also positive for myeloperoxidase, and a correlation between b-FGF-positive and total neutrophil counts was found. Conclusions: One of the major causes of stenosis in long-standing UC is fibrosis in the bowel wall, possibly induced by infiltrating inflammatory neutrophils producing b-FGF.


Gastroenterology Research and Practice | 2013

Clinical Study of the Relation between Mucosal Healing and Long-Term Outcomes in Ulcerative Colitis.

Kaoru Yokoyama; Kiyonori Kobayashi; Miyuki Mukae; Miwa Sada; Wasaburo Koizumi

Background and Objectives. Mucosal healing (MH) is considered an important therapeutic goal in ulcerative colitis (UC). We evaluate the severity of intestinal inflammation and clarify the relation between MH and long-term outcomes. Methods. The study group comprised 38 patients with UC in clinical remission on total colonoscopy who were followed up for at least 5 years. Clinical remission was defined as a Mayo score of 0 for both stool frequency and rectal bleeding. Colonoscopic findings were evaluated into 4 grades according to the Mayo endoscopic subscore (MES). Results. During clinical remission, the MES was 0 in only 24% of the patients, 1 in 40%, 2 in 26%, and 3 in 10%. Seventy-six percent of the patients thus had active disease on colonoscopy. After initial colonoscopy, the cumulative rate of remission maintenance was 100% in MES 0, 1 in 93%, 2 in 70%, and 3 in 50% at 6 months and 78%, 40%, 10%, and 0%, respectively, at 5 years (P < 0.001). Conclusion. Many patients with UC in clinical remission have active lesions. Patients with a higher MES have a higher rate of recurrence. To improve long-term outcomes, an MES of 0 should be the treatment goal.


Digestive Endoscopy | 2003

Clinical role of endoscopic ultrasonography for the diagnosis of early colorectal cancer and selecting the treatment procedure

Kiyonori Kobayashi; Mitsuhiro Kida; Tomoe Katsumata; Shigeru Yoshizawa; Kaoru Yokoyama; Miwa Sada; Masahiro Igarashi; Katsunori Saigenji

Background:  Accurate evaluation of the depth of tumor invasion, including the degree of submucosal invasion, is a prerequisite to selecting the treatment procedure for early colorectal cancer (CRC). The purpose of the present study was to evaluate the significance of endoscopic ultrasonography (EUS) for diagnosing the depth of invasion of early CRC and selecting the treatment procedure. We concurrently estimated the usefulness of three‐dimensional EUS (3‐D‐EUS) compared with that of conventional EUS.


Gastroenterology Research and Practice | 2012

Comparison of Diagnostic Accuracies of Various Endoscopic Examination Techniques for Evaluating the Invasion Depth of Colorectal Tumors

Satomi Haruki; Kiyonori Kobayashi; Kaoru Yokoyama; Miwa Sada; Wasaburo Koizumi

This study was designed to assess the clinical value of magnifying endoscopy combined with EUS for estimating the invasion depth of colorectal tumors. We studied 168 colorectal adenomas and carcinomas that were sequentially examined by conventional endoscopy followed by magnifying endoscopy and EUS in the same session to evaluate invasion depth. Endoscopic images obtained by each technique were reassessed by 3 endoscopists to determine whether endoscopic resection (adenoma, mucosal cancer, or submucosal cancer with slight invasion) or colectomy (submucosal cancer with massive invasion or advanced cancer) was indicated. The accuracy of differential diagnosis was compared among the examination techniques. The rate of correct differential diagnosis according to endoscopic examination technique was similar. The proportion of lesions that were difficult to diagnose was significantly higher for EUS (15.5%) than for conventional endoscopy and magnifying endoscopy. Among lesions that could be diagnosed, the rate of correct differential diagnosis was the highest for EUS (89.4%), but did not significantly differ among three endoscopic examination techniques. When it is difficult to evaluate the invasion depth of colorectal tumors on conventional endoscopy alone, the combined use of different examination techniques such as EUS may enhance diagnostic accuracy in some lesions.


Digestive Endoscopy | 2010

RECTAL GRANULAR-CELL TUMOR DIFFICULT TO DISTINGUISH FROM CARCINOID TUMOR

Teppei Nakanome; Kaoru Yokoyama; Hitomi Takeuchi; Satomi Haruki; Miwa Sada; Kiyonori Kobayashi; Katsunori Saigenji; Tomoe Katsumata; Atsuko Hara; Isao Okayasu

A 60‐year‐old man had a positive fecal occult‐blood test on a medical check‐up. Colonoscopy revealed a yellowish‐white submucosal tumor 8 mm in diameter in the rectum. Endoscopic ultrasonography showed a well‐demarcated mass with a homogeneous, low‐level, internal echo in the second to third layers of the rectal wall. A carcinoid tumor was suspected, and the mass was resected endoscopically. Histopathological examination revealed a granular‐cell tumor. Gastrointestinal granular‐cell tumors rarely arise in the rectum, and the preoperative diagnosis of small lesions is often difficult. In our patient, granular‐cell tumor was difficult to differentially diagnose because the endoscopic and endoscopic ultrasonographic findings closely resembled those of carcinoid tumor. Interestingly, the endoscopic characteristics of the rectal granular‐cell tumor in our patient resembled those of a carcinoid tumor.


World Journal of Gastrointestinal Endoscopy | 2013

Clinical usefulness of single-balloon endoscopy in patients with previously incomplete colonoscopy

Kiyonori Kobayashi; Miyuki Mukae; Taishi Ogawa; Kaoru Yokoyama; Miwa Sada; Wasaburo Koizumi

AIM To evaluate the clinical usefulness of single-balloon endoscopy (SBE) in patients in whom a colonoscope was technically difficult to insert previously. METHODS The study group comprised 15 patients (8 men and 7 women) who underwent SBE for colonoscopy (30 sessions). The number of SBE sessions was 1 in 7 patients, 2 in 5 patients, 3 in 1 patient, 4 in 1 patient, and 6 in 1 patient. In all patients, total colonoscopy was previously unsuccessful. The reasons for difficulty in scope passage were an elongated colon in 6 patients, severe intestinal adhesions after open surgery in 4, an elongated colon and severe intestinal adhesions in 2, a left inguinal hernia in 2, and multiple diverticulosis of the sigmoid colon in 1. Three endoscopists were responsible for SBE. The technique for inserting SBE in the colon was basically similar to that in the small intestine. The effectiveness of SBE was assessed on the basis of the success rate of total colonoscopy and the presence or absence of complications. We also evaluated the diagnostic and treatment outcomes of colonoscopic examinations with SBE. RESULTS Total colonoscopy was successfully accomplished in all sessions. The mean insertion time to the cecum was 22.9 ± 8.9 min (range 9 to 40). Abnormalities were found during 21 sessions of SBE. The most common abnormality was colorectal polyps (20 sessions), followed by radiation colitis (3 sessions) and diverticular disease of the colon (3 sessions). Colorectal polyps were resected endoscopically in 15 sessions. A total of 42 polyps were resected endoscopically, using snare polypectomy in 32 lesions, hot biopsy in 7 lesions, and endoscopic mucosal resection in 3 lesions. Fifty-six colorectal polyps were newly diagnosed on colonoscopic examination with SBE. Histopathologically, these lesions included 2 intramucosal cancers, 42 tubular adenomas, and 2 tubulovillous adenomas. The mean examination time was 48.2 ± 20.0 min (range 25 to 90). Colonoscopic examination or endoscopic treatment with SBE was not associated with any serious complications. CONCLUSION SBE is a useful and safe procedure in patients in whom a colonoscope is technically difficult to insert.


Clinical Endoscopy | 2016

Roles of Capsule Endoscopy and Single-Balloon Enteroscopy in Diagnosing Unexplained Gastrointestinal Bleeding.

Shohei Ooka; Kiyonori Kobayashi; Kana Kawagishi; Masaru Kodo; Kaoru Yokoyama; Miwa Sada; Satoshi Tanabe; Wasaburo Koizumi

Background/Aims: The diagnostic algorithms used for selecting patients with obscure gastrointestinal bleeding (OGIB) for capsule endoscopy (CE) or balloon-assisted enteroscopy (BE) vary among facilities. We aimed to demonstrate the appropriate selection criteria of CE and single balloon-assisted enteroscopy (SBE) for patients with OGIB according to their conditions, by retrospectively comparing the diagnostic performances of CE and BE for detecting the source of the OGIB. Methods: We investigated 194 patients who underwent CE and/or BE. The rate of positive findings, details of the findings, accidental symptoms, and hemostasis methods were examined and analyzed. Results: CE and SBE were performed in 103 and 91 patients, respectively, and 26 patients underwent both examinations. The rate of positive findings was significantly higher with SBE (73.6%) than with CE (47.5%, p<0.01). The rate of positive findings was higher in overt bleeding cases than in occult bleeding cases for both BE and SBE. Among the overt bleeding cases, the rate was significantly higher in ongoing bleeding cases than in previous bleeding cases. Conclusions: Both CE and SBE are useful to diagnose OGIB. For overt bleeding cases and ongoing bleeding cases, SBE may be more appropriate than CE because endoscopic diagnosis and treatment can be completed simultaneously.


World Journal of Gastroenterology | 2015

Clinical usefulness of endoscopic ultrasonography for the evaluation of ulcerative colitis-associated tumors

Kiyonori Kobayashi; Kana Kawagishi; Shouhei Ooka; Kaoru Yokoyama; Miwa Sada; Wasaburo Koizumi

AIM To evaluate the clinical usefulness of endoscopic ultrasonography (EUS) for the diagnosis of the invasion depth of ulcerative colitis-associated tumors. METHODS The study group comprised 13 patients with 16 ulcerative colitis (UC)-associated tumors for which the depth of invasion was preoperatively estimated by EUS. The lesions were then resected endoscopically or by surgical colectomy and were examined histopathologically. The mean age of the subjects was 48.2 ± 17.1 years, and the mean duration of UC was 15.8 ± 8.3 years. Two lesions were treated by endoscopic resection and the other 14 lesions by surgical colectomy. The depth of invasion of UC-associated tumors was estimated by EUS using an ultrasonic probe and was evaluated on the basis of the deepest layer with narrowing or rupture of the colonic wall. RESULTS The diagnosis of UC-associated tumors by EUS was carcinoma for 13 lesions and dysplasia for 3 lesions. The invasion depth of the carcinomas was intramucosal for 8 lesions, submucosal for 2, the muscularis propria for 2, and subserosal for 1. Eleven (69%) of the 16 lesions arose in the rectum. The macroscopic appearance was the laterally spreading tumor-non-granular type for 4 lesions, sessile type for 4, laterally spreading tumor-granular type for 3, semi-pedunculated type (Isp) for 2, type 1 for 2, and type 3 for 1. The depth of invasion was correctly estimated by EUS for 15 lesions (94%) but was misdiagnosed as intramucosal for 1 carcinoma with high-grade submucosal invasion. The 2 lesions treated by endoscopic resection were intramucosal carcinoma and dysplasia, and both were diagnosed as intramucosal lesions by EUS. CONCLUSION EUS provides a good estimation of the invasion depth of UC-associated tumors and may thus facilitate the selection of treatment.


Intestinal Research | 2018

Effect of elemental diet combined with infliximab dose escalation in patients with Crohn's disease with loss of response to infliximab: CERISIER trial

Tadakazu Hisamatsu; Reiko Kunisaki; Shiro Nakamura; Tomoyuki Tsujikawa; Fumihito Hirai; Hiroshi Nakase; Kenji Watanabe; Kaoru Yokoyama; Masakazu Nagahori; Takanori Kanai; Makoto Naganuma; Hirofumi Michimae; Akira Andoh; Akihiro Yamada; Tadashi Yokoyama; Noriko Kamata; Shinji Tanaka; Yasuo Suzuki; Toshifumi Hibi; Mamoru Watanabe

Many clinical observations have confirmed that anti-TNF-α mAbs are efficacious for the treatment of CD. Unfortunately, however, we are faced with a new complication: loss of response (LOR). In Japan at the time of this study, an infliximab (IFX) dose escalation regimen to 10 mg/kg was only allowed in patients who developed LOR during scheduled maintenance therapy with IFX (5 mg/kg every 8 weeks) according to the results of a preapproval clinical trial. However, we often encounter patients who cannot gain adequate control with increasing doses of 10 mg/kg of IFX in daily clinical practice. In this open-labeled prospective study (UMIN registration No. 000010058), patients with non-colonic CD who had developed LOR to scheduled administration of IFX (5 mg/kg every 8 weeks) were randomly assigned to IFX dose escalation (10 mg/kg every 8 weeks) with (combination group) or without (monotherapy group) an elemental diet (ED, 900–1200 kcal/day) for 56 weeks (Table 1, SuppleThe development and success of anti-tumor necrosis factor-α (anti-TNF-α) monoclonal antibodies (mAbs) have dramatically changed the therapeutic strategy of IBD and


Intestinal Research | 2018

Predicting outcomes to optimize disease management in inflammatory bowel disease in Japan: their differences and similarities to Western countries

Taku Kobayashi; Tadakazu Hisamatsu; Yasuo Suzuki; Haruhiko Ogata; Akira Andoh; Toshimitsu Araki; Ryota Hokari; Hideki Iijima; Hiroki Ikeuchi; Yoh Ishiguro; Shingo Kato; Reiko Kunisaki; Takayuki Matsumoto; Satoshi Motoya; Masakazu Nagahori; Shiro Nakamura; Hiroshi Nakase; Tomoyuki Tsujikawa; Makoto Sasaki; Kaoru Yokoyama; Naoki Yoshimura; Kenji Watanabe; Miiko Katafuchi; Mamoru Watanabe; Toshifumi Hibi

Inflammatory bowel disease (IBD), including Crohns disease (CD) and ulcerative colitis (UC), is a chronic inflammatory disease of the gastrointestinal tract, with increasing prevalence worldwide. IBD Ahead is an international educational program that aims to explore questions commonly raised by clinicians about various areas of IBD care and to consolidate available published evidence and expert opinion into a consensus for the optimization of IBD management. Given differences in the epidemiology, clinical and genetic characteristics, management, and prognosis of IBD between patients in Japan and the rest of the world, this statement was formulated as the result of literature reviews and discussions among Japanese experts as part of the IBD Ahead program to consolidate statements of factors for disease prognosis in IBD. Evidence levels were assigned to summary statements in the following categories: disease progression in CD and UC; surgery, hospitalization, intestinal failure, and permanent stoma in CD; acute severe UC; colectomy in UC; and colorectal carcinoma and dysplasia in IBD. The goal is that this statement can aid in the optimization of the treatment strategy for Japanese patients with IBD and help identify high-risk patients that require early intervention, to provide a better long-term prognosis in these patients.

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Masahiro Igarashi

Japanese Foundation for Cancer Research

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