Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Mariko Umezawa is active.

Publication


Featured researches published by Mariko Umezawa.


Digestion | 2017

Efficacy of Vonoprazan for Proton Pump Inhibitor-Resistant Reflux Esophagitis

Shintaro Hoshino; Noriyuki Kawami; Nana Takenouchi; Mariko Umezawa; Yuriko Hanada; Yoshimasa Hoshikawa; Tetsuro Kawagoe; Hirohito Sano; Yoshio Hoshihara; Tsutomu Nomura; Katsuhiko Iwakiri

Background: Vonoprazan (VPZ) is a novel potassium-competitive acid blocker that may be clinically beneficial for proton pump inhibitor (PPI)-resistant reflux esophagitis (RE). The aim of this study was to investigate the efficacies of VPZ therapy at 20 mg for 4 weeks in patients with PPI-resistant RE and VPZ maintenance therapy at 10 mg for 8 weeks in patients who have been successfully treated. Methods: Subjects comprised 24 patients with PPI-resistant RE (Los Angeles classification grade A/B/C/D: 3/7/11/3). After confirming PPI-resistant RE by endoscopy, 20 mg VPZ was administered. Endoscopy was performed 4 weeks after the initiation of VPZ. Symptoms were evaluated using the frequency scale for the symptoms of gastroesophageal reflux disease (FSSG). Maintenance therapy with 10 mg VPZ was performed and endoscopy was conducted after 8 weeks. Results: In 21 (87.5%) out of 24 patients, esophageal mucosal breaks were successfully treated by 20 mg VPZ. The median FSSG score was significantly lower on days 1-7, 14, and 28 after the initiation of VPZ than before its administration. Maintenance therapy with 10 mg VPZ prevented the relapse of esophageal mucosal breaks in 16 (76.2%) out of 21 patients. Conclusion: VPZ was effective for most patients with PPI-resistant RE.


Digestion | 2010

Characteristics of symptomatic reflux episodes in patients with non-erosive reflux disease who have a positive symptom index on proton pump inhibitor therapy.

Katsuhiko Iwakiri; Hirohito Sano; Yuriko Tanaka; Noriyuki Kawami; Mariko Umezawa; Seiji Futagami; Yoshio Hoshihara; Tsutomu Nomura; Masao Miyashita; Choitsu Sakamoto

Background and Aim: The reason that some reflux episodes evoke symptoms is poorly understood, therefore the aim of this study is to assess the determinants of reflux perception in patients with non-erosive reflux disease (NERD) on proton pump inhibitor (PPI) therapy. Methods: Ten NERD patients with persistent symptoms, despite double-dose PPI therapy, were included in this study. All patients had a positive symptom index (SI), which was determined by ambulatory 24-hour combined impedance-pH monitoring. Reflux episodes were identified and classified as acid, weakly acidic or weakly alkaline reflux and were considered symptomatic if patients recorded a symptom within 5 min after a reflux episode. Results: A total of 954 liquid reflux episodes were detected, including 135 (14.2%) acid, 782 (82.0%) weakly acidic, and 37 (3.9%) weakly alkaline. Overall, 59 (6.2%) reflux episodes were symptomatic and the majority (88.1%) of symptomatic reflux episodes were weakly acidic reflux. When reflux episodes were confined to the distal esophagus, there were very few reflux symptoms. Proximal reflux is significantly more likely to be associated with reflux symptoms, irrespective of the acidity of the refluxate or the duration of proximal reflux episodes. Conclusions: In NERD patients who have a positive SI on double-dose PPI therapy, the high proximal extent of refluxate is a major factor associated with reflux perception.


Journal of Gastroenterology | 2010

The appearance of rosette-like esophageal folds (“esophageal rosette”) in the lower esophagus after a deep inspiration is a characteristic endoscopic finding of primary achalasia

Katsuhiko Iwakiri; Yoshio Hoshihara; Noriyuki Kawami; Hirohito Sano; Yuriko Tanaka; Mariko Umezawa; Makoto Kotoyori; Tsutomu Nomura; Masao Miyashita; Choitsu Sakamoto

BackgroundIn healthy subjects who inspire deeply the lower esophagus usually opens, and the esophageal palisade vessels (EPVs) become visible. However, in patients with achalasia, the full extent of the EPVs does not become visible and, in addition, rosette-like esophageal folds appear in the lower esophagus. The aim of this study was to investigate whether or not these changes at the lower esophagus are characteristic findings of achalasia.MethodsA total of 34 patients with achalasia and no esophageal dilatation following deep inspiration were compared with 34 sex- and age-matched control subjects. Following a deep inspiration, the lower esophagus of all study cohorts was evaluated on (1) whether or not the full extent of the EPVs was visible, (2) whether or not rosette-like esophageal folds appeared in the lower esophagus, and (3) whether or not there were any gastric lesions.ResultsOne patient had secondary achalasia, and the remaining 33 patients had primary achalasia. In the control subjects, the full extent of the EPVs was clearly visible after a deep inspiration, and no esophageal folds appeared in the lower esophagus. In contrast, in the achalasia patients, EPVs were not observed in all patients after a deep inspiration, and rosette-like esophageal folds appeared in 33 of the 34 patients.ConclusionAfter a deep inspiration, the non-visibility of the EPVs and the appearance of rosette-like esophageal folds at the lower esophagus, which we have called “esophageal rosette”, are characteristic endoscopic findings of primary achalasia.


Digestion | 2017

Pathogenesis of Double-Dose Proton Pump Inhibitor-Resistant Non-Erosive Reflux Disease, and Mechanism of Reflux Symptoms and Gastric Acid Secretion-Suppressive Effect in the Presence or Absence of Helicobacter pylori Infection

Noriyuki Kawami; Nana Takenouchi; Mariko Umezawa; Shintaro Hoshino; Yuriko Hanada; Yoshimasa Hoshikawa; Hirohito Sano; Yoshio Hoshihara; Tsutomu Nomura; Eiji Uchida; Katsuhiko Iwakiri

Background: Various mechanisms have been suggested to be responsible for contributing to the occurrence of proton pump inhibitor (PPI)-resistant non-erosive reflux disease (NERD). The aims of this study were to clarify the pathogenesis of PPI-resistant NERD. Methods: Fifty-three patients with NERD, who had persistent reflux symptoms despite taking double-dose PPI, were included in this study. After excluding eosinophilic esophagitis (EoE) and primary esophageal motility disorder, esophageal impedance-pH monitoring was carried out. In symptom index (SI)-positive patients, the mechanism of SI positivity and the percent time with intragastric pH >4 were investigated according to the presence or absence of Helicobacter pylori infection. Results: One of the 53 patients had EoE, and 4 had primary esophageal motility disorder. Twenty-three and 2 patients were SI-positive for liquid and gas-only reflux respectively. Of 17 SI-positive, H. pylori-negative patients, 5 were SI-positive for acid reflux, whereas all of the H. pylori-positive patients were SI-positive for non-acid reflux. The percent time with intragastric pH >4 was significantly lower in the H. pylori-negative patients than in the H. pylori-positive patients. Conclusions: The pathogenesis of double-dose PPI-resistant NERD was identified in 57%. In some of H. pylori-negative patients, acid-related symptoms were observed. However, in H. pylori-positive patients, these symptoms were excluded by taking double-dose PPI.


Digestion | 2018

Pathogenesis of Potassium-Competitive Acid Blocker-Resistant Non-Erosive Reflux Disease

Noriyuki Kawami; Shintaro Hoshino; Yoshimasa Hoshikawa; Nana Takenouchi; Mariko Umezawa; Yuriko Hanada; Mitsuru Kaise; Katsuhiko Iwakiri

Background: The present study examined the pathogenesis of potassium-competitive acid blocker (P-CAB)-resistant non-erosive reflux disease (NERD). Methods: Forty-three patients with NERD, who had persistent reflux symptoms despite the administration of P-CAB, were included in this study. After excluding eosinophilic esophagitis and primary esophageal motility disorders, esophageal impedance-pH monitoring was performed. In symptom index (SI)-positive patients, the mechanism of SI-positivity and percent time with intragastric pH > 4 and with esophageal pH < 4 were investigated according to the presence or absence of Helicobacter pylori infection. Results: One (2.3%) of 43 patients had a primary esophageal motility disorder (Jackhammer esophagus). Eighteen (41.9%) and 3 (7%) patients were SI-positive for liquid and gas-only reflux, respectively, and the remaining 21 patients who were SI-negative (48.8%) had functional heartburn. All patients SI-positive for liquid reflux were SI-positive for weakly acidic reflux. Gastric acid was sufficiently suppressed by P-CAB, regardless of the presence or absence of H. pylori infection. Conclusions: The pathogenesis of P-CAB-resistant NERD was elucidated in 51% of patients. Symptoms in all patients SI-positive for liquid reflux were related to weakly acidic reflux, and symptoms related to acid reflux may be ruled out by the administration of P-CAB.


Esophagus | 2017

Erratum to: Effects of acotiamide on esophageal motility in healthy subjects: a randomized, double-blind, placebo-controlled crossover study

Shintaro Hoshino; Nana Takenouchi; Yuriko Hanada; Mariko Umezawa; Hirohito Sano; Noriyuki Kawami; Yoshimasa Hoshikawa; Tetsuro Kawagoe; Tsutomu Nomura; Yoshio Hoshihara; Katsuhiko Iwakiri

Background Acotiamide is a new drug that exhibits prokinetic activity by enhancing the release of acetylcholine. However, its effects on esophageal motility currently remain unknown. Therefore, we herein investigated the effects of acotiamide on esophageal motility in healthy, asymptomatic subjects.


Digestion | 2018

Efficacy of On-Demand Therapy Using 20-mg Vonoprazan for Mild Reflux Esophagitis

Mariko Umezawa; Noriyuki Kawami; Shintaro Hoshino; Yoshimasa Hoshikawa; Eriko Koizumi; Nana Takenouchi; Yuriko Hanada; Mitsuru Kaise; Katsuhiko Iwakiri

Background: The study aimed to evaluate the efficacy of on-demand therapy using 20-mg vonoprazan for mild reflux esophagitis (RE). Methods: On-demand therapy by taking one 20-mg tablet of vonoprazan only when reflux symptoms occurred was performed for 24 weeks using 30 patients with mild RE who were receiving maintenance therapy with proton pomp inhibitors (PPIs). The presence or absence of RE, degree of overall satisfaction with the treatment, score of symptoms, and fasting gastrin level before breakfast were examined before and after on-demand therapy. The number of tablets taken during the 24-week period was also noted. Results: One of the 30 patients dropped out of on-demand therapy 1 week after its initiation. Remission was maintained in 25 (86.2%) of the 29 patients (all 10 [100%] Los Angeles classification grade A patients and 15 (78.9%) of the 19 grade B patients). However, 4 grade B patients exhibited grade B relapse. There were no differences in the degree of overall satisfaction, score of symptoms or the gastrin level between PPI and on-demand therapies. The number of vonoprazan tablets taken during the observation period was 33 tablets (median)/24 weeks. Conclusion: On-demand therapy using 20-mg vonoprazan tablets is an effective alternative maintenance therapy for mild RE.


Journal of Gastroenterology | 2009

Acid and non-acid reflux in Japanese patients with non-erosive reflux disease with persistent reflux symptoms, despite taking a double-dose of proton pump inhibitor: a study using combined pH-impedance monitoring

Katsuhiko Iwakiri; Noriyuki Kawami; Hirohito Sano; Yuriko Tanaka; Mariko Umezawa; Makoto Kotoyori; Yoshio Hoshihara; Choitsu Sakamoto


Digestive Diseases and Sciences | 2009

Mechanisms of Excessive Esophageal Acid Exposure in Patients with Reflux Esophagitis

Katsuhiko Iwakiri; Noriyuki Kawami; Hirohito Sano; Yuriko Tanaka; Mariko Umezawa; Makoto Kotoyori; Yoshio Hoshihara; Choitsu Sakamoto


Journal of Gastroenterology | 2010

Predictors of a better outcome of pneumatic dilatation in patients with primary achalasia.

Yuriko Tanaka; Katsuhiko Iwakiri; Noriyuki Kawami; Hirohito Sano; Mariko Umezawa; Makoto Kotoyori; Yoshio Hoshihara; Tsutomu Nomura; Masao Miyashita; Choitsu Sakamoto

Collaboration


Dive into the Mariko Umezawa's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge