Publications by authors named "Kenta Hamada"

A hyperbolic metamaterial absorber has great potential for improving the performance of photo-thermoelectric devices targeting heat sources owing to its broadband absorption. However, optimizing its geometry requires considering numerous parameters to achieve absorption that aligns with the radiation spectrum. Here, we compare three algorithms using deep reinforcement learning for the optimization of a hyperbolic metamaterial absorber.

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Background And Aim: Lymphatic involvement is sometimes detected during routine examination of intramucosal (pT1a) gastric cancer resected endoscopically. However, its clinical significance and association with the risk of metastasis remain unknown.

Methods: This was a retrospective cohort study of 6797 consecutive patients with pT1a gastric cancers treated by endoscopic submucosal dissection (ESD) at three institutions in Japan from January 2005 to August 2023.

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Achalasia, a chronic esophageal motility disorder, increases the risk of esophageal squamous cell carcinoma. Despite effective treatment with peroral endoscopic myotomy (POEM), patients remain at risk of malignancy. We present the case of a 75-year-old Japanese woman diagnosed with achalasia who was found to have esophageal squamous cell carcinoma three months after POEM.

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Although esophagogastroduodenoscopy (EGD) is a widely used technique, the procedure is often associated with discomfort. This study aimed to analyze painful situations, their frequency, and factors associated with patient discomfort during EGD. This prospective observational study included patients scheduled to undergo EGD.

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  • Researchers studied the effects of ramucirumab (RAM) before nivolumab treatment in patients with advanced gastric cancer to see if it improved immune cell function and survival rates.
  • The study analyzed 52 patients' outcomes, comparing those who received RAM with those who did not, finding that the RAM group had significantly longer overall survival (8.5 months vs 6.9 months).
  • The results indicated that RAM usage before nivolumab may enhance survival, particularly in patients without peritoneal metastasis, who showed even better outcomes (23.8 months vs 7.7 months).
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  • The study focuses on elderly patients (75 years and older) with superficial esophageal squamous cell carcinoma (ESCC) and evaluates the effectiveness of endoscopic resection (ER) in extending life expectancy.
  • Data was collected from 208 patients over a 6.6-year median follow-up, showing a 5-year overall survival rate of 79.2%.
  • Independent factors like a good American Society of Anesthesiologists physical status (ASA-PS) and a prognostic nutritional index (PNI) of 44 or higher were identified as key indicators for recommending ER to improve survival outcomes.
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  • A study looked at the safety of continuing blood thinners (warfarin and DOACs) in patients needing a stomach procedure for early cancer.
  • It found that people taking warfarin didn't have any bleeding after the procedure, while some people taking DOACs did.
  • The researchers suggest that it's safer to keep using warfarin and that stopping DOACs too close to the procedure can lead to more bleeding problems.
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Objective The characteristics of gastric cancer in patients with atrophic mucosa and no apparent history of Helicobacter pylori eradication have not been thoroughly investigated. Therefore, this study examined the clinicopathological characteristics of gastric cancer in these patients. Methods We retrospectively examined the endoscopic and pathological characteristics of gastric cancer in patients who underwent endoscopic submucosal dissection.

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  • * A modified scale (m-ES) was created to quantify symptoms like dysphagia, regurgitation, and chest pain, revealing that nearly 5% of patients still experience significant persistent symptoms affecting their QOL.
  • * Results indicated that the m-ES correlates strongly with symptom severity and is more effective than the original Eckardt score in predicting persistent symptoms, with dysphagia and chest pain being the most common lingering issues.
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Background And Aim: Anticoagulant users with nonvalvular atrial fibrillation (NVAF) sometimes suffer from gastrointestinal bleeding (GIB) and have difficulty continuing the medication. Left atrial appendage closure (LAAC) has been developed for such situations. We aimed to clarify the clinical significance of a history of GIB in comparison to other factors in patients who had undergone LAAC.

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  • High-resolution manometry (HRM) and esophagography are key diagnostic tools for achalasia, but the different phenotypes and treatment outcomes for patients have not been fully understood.
  • A study involving 1824 treatment-naïve achalasia patients used machine learning to classify them into three distinct phenotypes based on various demographics and diagnostic findings.
  • The findings revealed differing clinical characteristics across the phenotypes and developed predictive models indicating that specific factors, such as high pre-POEM Eckardt scores, could signal a greater risk for persistent symptoms post-treatment.
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  • * This mini-review highlights various benign lesions that can occur in these regions, including dental issues, infections, and structural anomalies, and provides representative endoscopic images for better understanding.
  • * Endoscopists are encouraged to build their knowledge about these benign lesions for better diagnosis, while still recognizing the importance of collaborating with specialists like otolaryngologists or dentists when needed.
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Changes in hormone levels in patients with cancer cachexia after anamorelin administration have not been fully investigated. This study aimed to determine how anamorelin affects the endocrine system in patients with gastrointestinal cancer and cachexia. We prospectively enrolled 13 patients and comprehensively investigated their body weight and levels of serum albumin, hemoglobin A1c (HbA1c), and hormones before (week 0) and 3 and 12 weeks after anamorelin administration.

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  • Endoscopic submucosal dissection (ESD) is a minimally invasive treatment for superficial squamous cell cancer of the pharynx, but it may lead to aspiration pneumonia (AsP) due to postoperative pharyngeal deformities.
  • A study at Okayama University Hospital from 2006 to 2017 assessed the occurrence of AsP and pharyngeal deformation in 52 patients, finding a 3-year cumulative incidence of AsP at 9.0%.
  • Patients with prior radiotherapy and those with higher pharyngeal deformation grades (PDG 2 and 3) showed a significantly increased risk for AsP, with the high PDG group demonstrating a 23.9%
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  • Esophageal achalasia is divided into three subtypes (I, II, III) based on manometric findings, and each subtype exhibits distinct clinical features and treatment responses, indicating possible differences in their underlying causes.
  • Type III is the least common, characterized by the oldest patients and severe symptoms like chest pain, while type I has a higher incidence of lung complications, and type II patients often experience more weight loss.
  • Differential responses to treatment suggest type II has better outcomes with pneumatic dilatation, while type III tends to respond poorly; these findings are important for understanding achalasia's pathogenesis and guiding clinical management.
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Herein, we report two patients with autoimmune gastritis who had undergone multiple esophagogastroduodenoscopy procedures for 17 and 9 years, respectively, before their diagnosis. Instead, they had been diagnosed with and treated for Helicobacter pylori-associated gastritis. The correct diagnosis was made when scatterings of tiny whitish protrusions in the gastric mucosa were detected on esophagogastroduodenoscopy.

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Linked color imaging (LCI) can enhance the original color of each area and may useful to detect tumorous lesions during esophagogastroduodenoscopy. However, LCI may also enhance cancer-suspected non-cancerous regional color change. We conducted a retrospective image analysis to investigate the color characteristics of early gastric cancer (EGC) and cancer-suspected non-cancerous mucosa (CSM) in LCI.

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Background: Patients with familial adenomatous polyposis (FAP) risk developing multiple duodenal adenomas (MDAs), leading to duodenal cancer and death. We investigated the efficacy and safety of intensive downstaging polypectomy (IDP) for MDAs integrated with new-generation procedures.

Methods: This prospective phase II study, conducted at a tertiary cancer center, enrolled patients with FAP who had MDAs.

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Patients with familial adenomatous polyposis (FAP) are at increased risk of developing gastric neoplasms. However, endoscopic findings have not been sufficiently investigated. We investigated the phenotypic expression of gastric adenoma (low-grade dysplasia) and gastric cancer (high-grade dysplasia or carcinoma) in patients with FAP and clarified their relationships to endoscopic findings.

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Background/aims: The safety of gastric endoscopic submucosal dissection (ESD) in users of a P2Y12 receptor antagonist (P2Y12RA) under current guidelines has not been verified.

Methods: Patients treated by gastric ESD at Okayama University Hospital between January 2013 and December 2020 were registered. The postoperative bleeding rates of patients (group A) who did not receive any antithrombotic drugs; patients (group B) receiving aspirin or cilostazol monotherapy; and P2Y12RA users (group C) those on including monotherapy or dual antiplatelet therapy were compared.

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An 82-year-old Japanese man underwent esophagogastroduodenoscopy for postprandial epigastric discomfort. The patient was diagnosed with hypozincemia with a serum zinc level of 63μg/dL (normal range:80-130μg/dL), and he had commenced oral intake of zinc acetate 1 month before the esophagogastroduodenoscopy. Endoscopy showed erosions with white-coated mucosa surface adhesions and erythema on the lesser curvature of the gastric body.

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A 45-year-old Japanese man underwent esophagogastroduodenoscopy, which revealed spotty redness at the gastric fornix, mucosal swelling, diffuse redness in the corpus, and mucosal atrophy in the gastric angle and antrum. Histological examination showed rod-shaped bacteria that appeared larger than . The patient tested positive for rapid urease test, and serum anti- IgG antibody test results were negative.

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