Publications by authors named "Osamu Kawamura"

Background: Although dysphagia and chest pain are the two most common symptoms in patients with achalasia, the mechanism of evoking symptoms is still unknown. The aim of this study was to reveal the relationship between symptoms and the subtypes of achalasia defined by the Chicago classification.

Methods: A total of 71consecutive patients with newly diagnosed achalasia were enrolled between March 2009 and December 2017.

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In Japan, with the increasing prevalence of gastroesophageal reflux disease (GERD) and growing public interest, the Japanese Society of Gastroenterology issued Evidence-based Clinical Practice Guidelines for GERD (1st edition) in 2009 and a revised 2nd edition in 2015. A number of studies on GERD were subsequently conducted in Japan and abroad, and vonoprazan, a potassium-competitive acid blocker (P-CAB), became available for the first time in Japan in February 2015. The revised 3rd edition (Japanese edition), which incorporates new findings and information, was published in April 2021.

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Article Synopsis
  • * The research analyzed HRM studies from various global motility centers, finding that 74.6% of participants had normal results, with ineffective esophageal motility (IEM) being the most common abnormal finding (15.1%).
  • * The study concluded that motor abnormalities are rare in healthy individuals, with IEM being the primary issue, and noted that thresholds for HRM measurements differ depending on the HRM system and whether the patient was upright or supine.
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Background: Esophagogastric junction contractile integral (EGJ-CI) and EGJ morphology are high-resolution manometry (HRM) metrics that assess EGJ barrier function. Normative data standardized across world regions and HRM manufacturers are limited.

Methods: Our aim was to determine normative EGJ metrics in a large international cohort of healthy volunteers undergoing HRM (Medtronic, Laborie, and Diversatek software) acquired from 16 countries in four world regions.

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Objective: Limitations of existing impedance-pH thresholds include small sample size of normative studies, inclusion of artefactual pH drops and incorrect identification of impedance reflux events. We aimed to obtain new impedance-pH thresholds from expert consensus analysis of tracings from a large number of healthy subjects.

Design: Of 541 studies performed worldwide using two different systems (Diversatek, USA, and Laborie, Netherlands), 150 tracings with oesophageal diagnoses, behavioural disorders and study-related artefacts were excluded.

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Background: Supragastric belching (SGB) may play a role in the pathophysiology of proton pump inhibitors (PPIs)-refractoriness in gastroesophageal reflux disease (GERD). SGB may be present in up to 40% of reflux symptoms in PPI-refractory GERD. Most reports on SGB have come from Western countries, and little is known about the prevalence and relevance of SGB in Asian refractory GERD patients.

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Background: Vonoprazan (V), a potassium-competitive acid blocker, has a more durable acid-inhibitory effect as compared with standard-dose proton pump inhibitors (PPIs) but has not been compared with 2-4 times higher daily PPI doses administered in two divided doses.

Aims: To evaluate the acid-inhibitory effect of V 10/20 mg once-daily (OD; V10/V20) vs rabeprazole (R) 10/20 mg twice-daily (BID; R20/R40) in healthy Japanese volunteers.

Methods: This multicentre, randomised, open-label, two-period, crossover study compared V10 or V20 vs R20, or V20 vs R40 using three cohorts of 10 healthy Japanese adults.

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We combined immunoaffinity column (IAC) and enzyme-linked immunosorbent assay (ELISA) methods to develop a rapid method to analyze total aflatoxin (AF) in foods, using a large number of samples. Using newly developed monoclonal antibodies, with high cross-reactivity and high organic solvent tolerance, we developed the IAC-ELISA method. Our IAC-ELISA method showed a good correlation with the high-performance liquid chromatography method for corn samples spiked with total AF.

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Background: The values of the parameters in the Chicago classification measured by a high-resolution manometry (HRM) system with the Unisensor catheter (Starlet) are significantly different from those measured by the ManoScan. The contraction vigor is categorized by values of the distal contractile integral (DCI) in the Chicago classification v3.0; however, reference values of the DCI in the Starlet and the clinical impact of the different reference values in the Starlet and ManoScan on diagnosing esophageal motility disorders are not known.

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Background: Esophageal motility abnormalities (EMAs) and interstitial lung diseases (ILDs) are often seen in patients with systemic sclerosis (SSc). Gastroesophageal reflux disease (GERD) could be associated with ILDs, but it is not fully understood if ILDs are caused by GERD or SSc itself.

Methods: A total of 109 patients with SSc who underwent high-resolution manometry were enrolled.

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Background/aim: We evaluated the efficacy of vonoprazan (VPZ), a novel potassium-competitive acid blocker, in patients with proton pump inhibitor (PPI)-refractory gastroesophageal reflux disease (GERD), exhibiting continued pathological esophageal acid exposure (EAE).

Methods: Despite ≥8 weeks of appropriate PPI therapy, patients with -persistent reflux symptoms and pathological EAE times (EAETs ≥4%) were invited to switch to VPZ treatment. After an 8-week-course of once-daily VPZ (20 mg), multichannel intraluminal impedance-pH (MII-pH) monitoring was repeated to compare gastric acid exposure times (GAETs), EAETs, and other reflux parameters relative to the baseline values.

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Aflatoxin B₁ (AFB₁), a mycotoxin found in food and feed, exerts harmful effects on humans and animals. The liver is the earliest target of AFB₁, and its effects have been evaluated in animal models exposed to acute or chronic doses. Considering the possibility of sporadic ingestion of AFB₁-contaminated food, this study investigated the impact of a single oral dose of AFB₁ on liver function/cytokines and the lymphoproliferative response in mice.

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We previously reported that cascade stomach was associated with reflux symptoms and esophagitis. Delayed gastric emptying has been believed to initiate transient lower esophageal sphincter relaxation (TLESR). We hypothesized that cascade stomach may be associated with frequent TLESR with delayed gastric emptying.

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Aflatoxin M₁ (AFM₁) is an important biomarker that can be used to evaluate aflatoxin exposure in both humans and animals. The aim of this study was to evaluate the exposure degree of infants to AFM₁ through consumption of breast milk and infant powdered milk in Brazil. For this purpose, the estimated daily intake (EDI) for infants was calculated based on the AFM₁ levels analyzed in 94 breast milk (BM) samples collected in Southern Brazil, and 16 infant powdered milk (IPM) samples commonly commercialized in Brazil.

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Monitoring of esophageal impedance is a technique for determining the physical characteris- tics (liquid, gas, or mixed) of refluxate, while impedance monitoring combined with pH recording makes it possible to assess the acidity of reflux(acid or non-acid). Assessment is usually performed by the total acid exposure time (%time pH< 4) and symptom-reflux asso- ciations including acidic and non-acidic reflux. This monitoring is quite useful for evaluation of proton pump inhibitor-resistant gastroesophageal reflux disease or non-erosive reflux disease.

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As an increase in gastroesophageal reflux disease (GERD) has been reported in Japan, and public interest in GERD has been increasing, the Japanese Society of Gastroenterology published the Evidence-based Clinical Practice Guidelines for GERD (1st edition) in 2009. Six years have passed since its publication, and there have been a large number of reports in Japan concerning the epidemiology, pathophysiology, treatment, and Barrett's esophagus during this period. By incorporating the contents of these reports, the guidelines were completely revised, and a new edition was published in October 2015.

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Background/aims: Twenty-four-hour esophageal impedance and pH monitoring allows detection of all types of reflux episodes and is considered the best technique for identifying gastroesophageal refluxes. However, normative data for the Japanese population are lacking. This multicenter study aimed to establish the normal range of 24-hour esophageal impedance and pH data both in the distal and the proximal esophagus in Japanese subjects.

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Background: We recently demonstrated that cascade stomach detected by barium studies was correlated with upper gastrointestinal symptoms. We developed a new endoscopic classification of cascade stomach and examined its relationship with reflux esophagitis.

Methods: Study 1: the classification (grades 0-3) was based on detecting a ridge that runs from the cardia toward the anterior wall crossing the greater curvature.

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Two cases of intravascular lymphoma (IVL) were diagnosed by endoscopic biopsy. Both patients were admitted to our hospital with a fever of an unknown origin. An elevated serum level of soluble interleukin-2 receptor antibody suggested IVL.

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Polyethylene glycol- (PEG-) based bowel preparations for colonoscopies are often poorly tolerated due to the large volumes of fluid intake required. We compared low-volume "modified" PEG + ascorbic acid (AJG522) with standard PEG with electrolytes (PEG+E) in addition to a stimulant laxative and an agent to improve bowel function for the bowel cleansing before colonoscopy to evaluate its efficacy, safety, and acceptability. Outpatients scheduled to undergo colonoscopy were randomized to receive either AJG522 or PEG+E.

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Background: Patients with proton pump inhibitor (PPI)-resistant nonerosive reflux disease (NERD) include subgroups that have markedly different pathophysiology. This study aimed to clarify the pathophysiology of NERD by esophageal manometry with 24-hour esophageal impedance and pH monitoring.

Methods: Eighteen consecutive outpatients referred to our expert center for functional gastrointestinal motility with suspected PPI-resistant NERD were enrolled.

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