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Dive into the research topics where Yugo Iwaya is active.

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Featured researches published by Yugo Iwaya.


Helicobacter | 2013

High Levels of FOXP3+ Regulatory T Cells in Gastric MALT Lymphoma Predict Responsiveness to Helicobacter pylori Eradication

Yugo Iwaya; Motohiro Kobayashi; Masanobu Momose; Nobuyoshi Hiraoka; Yasuhiro Sakai; Taiji Akamatsu; Eiji Tanaka; Haruo Ohtani; Minoru Fukuda; Jun Nakayama

Although Helicobacter pylori eradication is a first‐line treatment of gastric MALT lymphoma, roughly 25% of patients do not respond to treatment. CD4+ FOXP3+ regulatory T (Treg) cells regulate immune responses in physiological conditions and various inflammatory conditions, including H. pylori‐associated diseases. Our goal was to determine how Treg cells affect responsiveness to H. pylori eradication therapy.


Case Reports in Gastroenterology | 2012

Helicobacter pylori-Negative Primary Rectal MALT Lymphoma: Complete Remission after Radiotherapy

Takuma Okamura; Tomoaki Suga; Yugo Iwaya; Tetsuya Ito; Shuichi Yokosawa; Norikazu Arakura; Hiroyoshi Ota; Eiji Tanaka

Rectal mucosa-associated lymphoid tissue (MALT) lymphoma is a rare condition. Although the majority of patients undergo surgical resection, a definitive treatment for rectal MALT lymphoma has not yet been established. In the present study, we report the outcome of radiotherapy in 3 patients with rectal MALT lymphoma. Our cohort ranged from 56 to 65 years of age. The male/female ratio was 1:2, and all patients were in stage I (Lugano classification) of the disease. Endoscopic findings revealed elevated lesions resembling submucosal tumors in 2 patients, and a sessile elevated lesion with a nodular surface in 1 patient. One of the 3 patients underwent magnifying endoscopy with crystal violet staining that demonstrated a type I pit pattern (Kudo’s classification) lesion with a broad intervening area caused by the upthrust of the tumor from the submucosa. All patients tolerated radiotherapy at doses of 30 Gy without major complications and achieved complete remission. Follow-up ranged from 13 to 75 months (mean 51.0 months), revealing no recurrence of MALT lymphoma. As such, we propose radiotherapy to be a safe and effective means for treating rectal MALT lymphoma.


Histopathology | 2014

Reduced expression of αGlcNAc in Barrett's oesophagus adjacent to Barrett's adenocarcinoma – a possible biomarker to predict the malignant potential of Barrett's oesophagus

Yugo Iwaya; Osamu Hasebe; Naohiko Koide; Kei Kitahara; Tomoaki Suga; Akihiro Shinji; Takashi Muraki; Shuichi Yokosawa; Shigenori Yamada; Norikazu Arakura; Eiji Tanaka; Jun Nakayama

Gastric gland mucin contains O‐glycans exhibiting terminal α1,4‐linked N‐acetylglucosamine residues (αGlcNAc). Recently we demonstrated that mice deficient in αGlcNAc in gastric gland mucin develop gastric adenocarcinoma spontaneously, indicating that αGlcNAc is a tumour suppressor for gastric cancer. However, the role of αGlcNAc in Barretts oesophagus (BO) remains unknown. In this study, we investigated whether reduced αGlcNAc expression in BO is associated with development of Barretts adenocarcinoma (BAC).


Pathology | 2015

Superficially located enlarged lymphoid follicles characterise nodular gastritis

Takuma Okamura; Yasuhiro Sakai; Hitomi Hoshino; Yugo Iwaya; Eiji Tanaka; Motohiro Kobayashi

Summary Nodular gastritis is a form of chronic Helicobacter pylori gastritis affecting the gastric antrum and characterised endoscopically by the presence of small nodular lesions resembling gooseflesh. It is generally accepted that hyperplasia of lymphoid follicles histologically characterises nodular gastritis; however, quantitative analysis in support of this hypothesis has not been reported. Our goal was to determine whether nodular gastritis is characterised by lymphoid follicle hyperplasia. The number, size, and location of lymphoid follicles in nodular gastritis were determined and those properties compared to samples of atrophic gastritis. The percentages of high endothelial venule (HEV)-like vessels were also evaluated. The number of lymphoid follicles was comparable between nodular and atrophic gastritis; however, follicle size in nodular gastritis was significantly greater than that seen in atrophic gastritis. Moreover, lymphoid follicles in nodular gastritis were positioned more superficially than were those in atrophic gastritis. The percentage of MECA-79+ HEV-like vessels was greater in areas with gooseflesh-like lesions in nodular versus atrophic gastritis. Superficially located hyperplastic lymphoid follicles characterise nodular gastritis, and these follicles correspond to gooseflesh-like nodular lesions observed endoscopically. These observations suggest that MECA-79+ HEV-like vessels could play at least a partial role in the pathogenesis of nodular gastritis.


Gastroenterology Clinics of North America | 2015

Screening to Identify and Eradicate Helicobacter pylori Infection in Teenagers in Japan

Taiji Akamatsu; Takuma Okamura; Yugo Iwaya; Tomoaki Suga

The purpose of this study was to elucidate the prevalence and effect of Helicobacter pylori infection in Japanese teenagers. The study subjects were students ages 16 to 17 from one high school studied between 2007 and 2013. Students who tested positive on this screening examination underwent esophagogastroduodenoscopy and biopsy samples to determine their H pylori status using culture and histology. Cure of H pylori infections was determined by urea breath test. The low rate of prevalence of H pylori infection in present Japanese teenagers makes it possible and cost effective to perform examinations and carry out treatment of this infection in nationwide health screenings of high school students.


Clinical Journal of Gastroenterology | 2013

A case of Helicobacter heilmannii-associated primary gastric mucosa-associated lymphoid tissue lymphoma achieving complete remission after eradication

Takuma Okamura; Yugo Iwaya; Shuichi Yokosawa; Tomoaki Suga; Norikazu Arakura; Takehisa Matsumoto; Naoko Ogiwara; Kayoko Higuchi; Hiroyoshi Ota; Eiji Tanaka

A 46-year-old man underwent gastrointestinal endoscopy while visiting the hospital for a general physical check-up. Coarse mucosa in the antrum with superficial erosions was found by endoscopic gastrointestinal examination, but no atrophic changes were seen in the corpus. Histopathological examination of gastric biopsy specimens revealed mucosa-associated lymphoid tissue (MALT) lymphoma. Although Helicobacter pylori was not detected in our patient, H. heilmannii was identified histologically and by polymerase chain reaction analysis, resulting in the diagnosis of H. heilmannii-associated gastric MALT lymphoma. We successfully eradicated H. heilmannii and achieved complete remission of gastric MALT lymphoma by antibiotic therapy. H. heilmannii usually causes milder gastritis than H. pylori, but it has been more closely associated with MALT lymphoma. As such, when H. pylori infection is excluded in patients with gastric MALT lymphoma, physicians should next consider the possibility of H. heilmannii. Furthermore, our research suggests that eradication therapy is effective for treatment of localized H. heilmannii-associated gastric MALT lymphoma.


Clinical Journal of Gastroenterology | 2016

A case of simultaneous esophageal squamous cell carcinoma and Barrett’s adenocarcinoma

Tomoo Yamazaki; Yugo Iwaya; Mai Iwaya; Takayuki Watanabe; Ayako Seki; Yasuhide Ochi; Etsuo Hara; Tomohiro Sekiguchi; Noriko Hosaka; Norikazu Arakura; Eiji Tanaka; Osamu Hasebe

A 77-year-old male with a long history of alcohol consumption and smoking was admitted for hoarseness and dysphagia. Computed tomography revealed thickening of the middle intrathoracic esophageal wall and multiple mediastinal lymph node swellings. Esophagogastroduodenoscopic examination disclosed an advanced-stage squamous cell carcinoma lesion in the middle intrathoracic esophagus with synchronous early stage Barrett’s adenocarcinoma. The patient underwent endoscopic submucosal dissection for the adenocarcinoma followed by chemoradiation therapy for the squamous cell carcinoma. In spite of their common risk factors, the simultaneous manifestation of esophageal squamous cell carcinoma and Barrett’s adenocarcinoma is extremely rare and requires further study.


Pathology International | 2015

Principal cells in gastric neoplasia of fundic gland (chief cell predominant) type show characteristics of immature chief cells.

Hiroyoshi Ota; Dai Yamaguchi; Mai Iwaya; Mikiko Kobayashi; Nobuyuki Tateiwa; Yugo Iwaya; Masanobu Momose; Takeshi Uehara

To the Editor: In the normal gastric fundic mucosa, the digestive-enzymes secreting chief cells differentiate from mucous neck cells via the transdifferentiation route. Mucous neck cells possess MUC6 bearing GlcNAcα1→4Galβ→R structures specifically recognize by paradoxical Concanavalin A staining and monoclonal antibody HIK1083 (HIK1083 mAb), TFF2, which is a lectin binding with high specificity to O-linked α1,4-GlcNAc-capped hexasaccharides on gastric mucin, and pepsinogen I. Chief cells tend to lose MUC6 and TFF2


Internal Medicine | 2015

Helicobacter pylori -negative Differentiated Adenocarcinoma of the Stomach

Tadanobu Nagaya; Naoki Tanaka; Yugo Iwaya; Yoko Jimbo; Toshiharu Tatai; Tetsuya Ito; Ayako Seki; Kenichi Suzawa; Yasuhide Ochi; Etsuo Hara; Manabu Takata; Toshiaki Otsuki; Mai Iwaya; Noriko Hosaka; Norikazu Arakura; Eiji Tanaka; Osamu Hasebe

A 58-year-old Japanese man was diagnosed with differentiated adenocarcinoma of the stomach. Histological findings of the resected specimen revealed well- to moderately-differentiated tubular adenocarcinoma (tub1, tub2), 13 mm in diameter, which invaded into the submucosa (SM1, 300 μm) and lymphovascular lumen (ly1). Serum antibody against Helicobacter pylori (Hp) and the (13)C-urea breath test were negative, and there were no atrophic changes in the tumor-adjacent mucosa. The immunohistochemical analysis showed that gastric mucin (MUC5AC) was strongly positive and intestinal mucin (MUC2) was weakly and partially positive. According to these results, the final diagnosis of Hp-negative well-differentiated early gastric cancer was made.


Clinical Journal of Gastroenterology | 2017

Massive ascites caused by intra-pancreatic arterioportal fistula: a rare complication of chronic pancreatitis

Tomoo Yamazaki; Yasuhide Ochi; Naoki Tanaka; Takayuki Watanabe; Yugo Iwaya; Ayako Seki; Etsuo Hara; Eiji Tanaka; Tomoharu Watanabe; Shun Imai; Osamu Hasebe

An 86-year-old man with a long-term habit of ethanol consumption was admitted due to massive transudate ascites and leg edema. Abdominal computed tomography revealed a dilated main pancreatic duct and atrophied pancreatic parenchyma, leading to the diagnosis of chronic pancreatitis. Moreover, the portal vein was enhanced in the early arterial phase, which indicated the presence of an arterioportal fistula. The fistula was located between the posterior superior pancreaticoduodenal artery and the portal vein near a pancreatic retention cyst. Transarterial coil embolization dramatically improved the ascites. Arterioportal fistula and ensuing ascites should be recognized as a complication of chronic pancreatitis.

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