Publications by authors named "Ryuichi Yamamoto"

Although naloxone is an antagonist of the opioid µ receptor, its effect on the peripheral sympathetic nerve function in the blood vessels has not yet been definitively elucidated. Therefore, we examined the effects of naloxone on vasoconstriction of the vascular smooth muscle of rats. Isolated rat mesenteric vascular-intestinal loop preparations were treated with either endogenous or exogenous α adrenoceptor agonists followed by prazosin, a selective antagonist of the α adrenoceptor, or naloxone, and noradrenaline overflow was measured.

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Varicose veins are common lower extremity venous disorders characterized by dilated veins and incompetent valves. Although maintaining the required vein wall tone for adaptive responses depends on a proper contractile function of the human saphenous smooth muscle, the contractile properties of varicose veins are mostly unknown. We investigated the relationship between contractile responses and the internal diameter of human saphenous varicose veins.

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Rho kinase inhibitor fasudil exerts therapeutic effects against vasospasms. In this study, we aimed to compare its suppressive effects on serotonin (5-HT)- and noradrenaline (NAd)-induced contractions of human endothelium-denuded internal thoracic arteries (ITAs) and saphenous veins (SVs). NAd and 5-HT induced concentration-dependent contractions in both ITAs and SVs.

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The colonoscope shaft loop can be unwound by establishing a loop in the universal cord of the colonoscope to maintain the same endoscopic view during colorectal endoscopic resections.

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Recently, there has been a significant increase in the utilization of self-expandable metallic stents (SEMSs) for treating malignant colorectal obstructions through colorectal stenting. The mechanical properties of SEMSs are usually considered to affect clinical outcomes of patients with malignant colorectal obstructions. : This single-arm, prospective, multicenter study of SEMS with a lower axial force and high axial force zero-border included 200 patients with malignant colorectal obstruction.

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Article Synopsis
  • Simple hepatic cysts (SHC) are usually harmless and discovered by chance during imaging; treatment is only necessary for symptomatic cases.
  • The study analyzed the safety and effectiveness of endoscopic ultrasonography (EUS)-guided drainage for treating symptomatic SHC, comparing it to traditional methods like percutaneous catheter drainage (PCD) with minocycline sclerotherapy.
  • Results showed that EUS-guided drainage was successful with a 100% reduction in cyst size and a shorter hospital stay (7 days), making it a promising alternative to PCD and surgery.
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The collection and use of large-scale medical information for developing artificial intelligence engines are actively ongoing. In Japan, collection systems have been built to collect data for medical image analysis and disease repositories. In the experimental project for the next generation medical infrastructure law, a centrally integrated basic system was developed, and standardized electronic medical record (EMR) storage data distributed to each hospital were transferred into one data center and imported to a database for secondary use.

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  • - Brazilian propolis (AF-08), rich in flavonoids and used as folk medicine, may help reduce cardiovascular disease risk by inhibiting platelet aggregation, which is linked to thrombus formation.
  • - In laboratory tests, AF-08 demonstrated significant inhibition of collagen-induced platelet aggregation without affecting blood coagulation metrics like prothrombin time and activated partial thromboplastin time.
  • - The flavonoids found in AF-08, particularly apigenin and chrysin, are suggested to play a key role in preventing platelet aggregation, potentially lowering the risk of arterial thrombus formation and cardiovascular diseases.
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Sarpogrelate, a selective 5-hydroxytryptamine (5-HT) receptor antagonist, inhibits 5-HT-induced platelet aggregation and vasoconstriction. It improves ischemic symptoms in patients with arteriosclerosis obliterans. M-1 is a major metabolite of sarpogrelate, and has been reported to show a higher affinity for the 5-HT receptor on platelets than sarpogrelate.

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A secure data collection infrastructure was implemented in which Health Level-7 (HL7) Fast Healthcare Interoperative Resources (FHIR) was applied according to standardized electronic medical record (EMR) storage. This infrastructure aims to facilitate rapid secondary use of EMR data in cross-institutional analyses on the basis of the Standardized Structured Medical Information eXchange (SS-MIX), Japan's domestic standard for EMR export. Existing EMR storage comprised enormous numbers of HL7 v2 messages; therefore, the user interface and database structure are basically defined according to the HL7 v2 data types and message structures, causing difficulty in rapid extraction for researches by clinicians.

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Background/aims: The aim of this study was to evaluate the safety and efficacy of partially covered self-expandable metallic stents (PCSEMS) in patients undergoing neoadjuvant chemo(radio) therapy (NAC) for pancreatic cancer (PC).

Methods: This was a prospective multicenter study to evaluate the safety and efficacy of PCSEMS in patients receiving NAC for resectable and borderline resectable PC. The primary endpoint was the rate of recurrent biliary obstruction (RBO).

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To prevent worsening of diabetes mellitus, we conducted a developmental research of personal health record (PHR), whereby affected individuals, medical staff and an insurer cooperate and manage effective treatment. Medical expenses can be suppressed by preventing the onset of lifestyle-related diseases. Companies can benefit from improved employee productivity by promoting healthy and efficient working styles.

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This paper presents results concerning the traceability of a secure data collection infrastructure based on the Bloom Filter involving standardized electronic medical record (EMR) storage. The objective of this infrastructure is to facilitate rapid secondary use of exported EMR data in cross-patient or cross-institutional analyses based on the Standardized Structured Medical Information eXchange (SS-MIX), Japan's domestic standard for EMR export. Secondary use of EMR data should be based on the principle of patient consent.

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It is expected that a large amount of data related to diabetes and other chronic diseases will be generated. However, databases constructed without standardized data item sets can be limited in their usefulness. To address this, the Collaborative Committee of Clinical Informatization in Diabetes Mellitus was established in 2011 by the Japan Diabetes Society and Japan Association for Medical Informatics.

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It is expected that a large amount of data related to diabetes and other chronic diseases will be generated. However, databases constructed without standardized data item sets can be limited in their usefulness. To address this, the Collaborative Committee of Clinical Informatization in Diabetes Mellitus was established in 2011 by the Japan Diabetes Society and Japan Association for Medical Informatics.

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Many hypertensive animal models have been developed and used to elucidate the pathophysiology of hypertension and to develop antihypertensive drugs. Among them, the spontaneous hypertensive rat (SHR), deoxycorticosterone acetate (DOCA)-treated and high salt intake rat (DOCA-salt), and high sodium-fed Dahl salt-sensitive rat (HS) models are commonly used. Multiple studies have been conducted, however, elevation in blood pressure in these models due to the reactivity of adrenergic vasoconstriction has not been well characterized in a centralized experiment.

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Article Synopsis
  • Pancreatic cysts can be benign, premalignant, or malignant, with endometrial cysts being a rare type that's tough to diagnose before surgery.
  • A case of a 26-year-old patient who had abdominal pain and was found to have a large pancreatic cyst is reported, where lab tests indicated inflammation but normal tumor markers.
  • Following surgery, the presence of endometriotic cysts was confirmed, highlighting the rarity of such cases and the challenges in diagnosing them preoperatively, often leading to unnecessary surgical procedures.
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This paper describes a secure data collection infrastructure involving standardized electronic medical record (EMR) storage and Private Set Intersection, a secure data collection technology based on Bloom filter. The objective of this infrastructure is to facilitate rapid secondary use of exported EMR data in cross-patient or cross-institutional analyses based on the Standardized Structured Medical Information eXchange (SS-MIX), Japan's domestic standard for EMR exporting. Design of the infrastructure and its underlying concepts are described herein.

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Ulcerative colitis (UC) is characterized by erosions of the intestinal mucosa. The number of patients with UC has recently been increasing rapidly. Since the diagnosis of UC is complex and difficult, a simple, rapid, noninvasive technique for diagnosing UC is needed urgently.

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Studies indicate that 5-hydroxytryptamine (5-HT) released from activated platelets in coronary artery bypass grafting (CABG) induces 5-HT receptor-mediated graft spasm. We previously reported that 5-HT-induced constriction of human endothelium-denuded saphenous vein (SV) was significantly augmented in patients with diabetes mellitus (DM) than in patients without DM (non-DM), without changes in the levels of the membrane-bound 5-HT receptor of their smooth muscle cells. Although the internal thoracic artery (ITA) is the key graft conduit for CABG, the effect of DM on the ITA graft spasm is still unclear.

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  • This study compares endoscopic nasobiliary drainage (ENBD) and endoscopic biliary stent (EBS) as preoperative treatments for hilar malignant biliary obstruction (MBO) using data from 374 cases across 29 centers.
  • The research found that while ENBD had a high technical success rate (94.6%), 21.9% of patients experienced adverse events, and over half (61.5%) required preoperative re-interventions, mostly unplanned.
  • Ultimately, the analysis suggests that ENBD does not offer significant advantages over EBS, and unplanned re-interventions are linked to poorer outcomes for patients with resectable hilar MBO.
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Japan was once progressive in the digitalization of healthcare fields but unfortunately has fallen behind in terms of the secondary use of data for public interest. There has recently been a trend to establish large-scale health databases in the nation, and a conflict between data use for public interest and privacy protection has surfaced as this trend has progressed. Databases for health insurance claims or for specific health checkups and guidance services were created according to the law that aims to ensure healthcare for the elderly; however, there is no mention in the act about using these databases for public interest in general.

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