Publications by authors named "Yoichi Yamamoto"

Background: Endoscopic resection (ER) of non-ampullary duodenal epithelial tumors (NADETs) is associated with a high incidence of delayed bleeding (DB). While previous reports have identified composite risk factors for delayed adverse events, including both DB and delayed perforation, the specific factors associated with DB remain unclear. This study aimed to identify factors associated with DB after ER of NADETs.

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Background And Aim: We aimed to elucidate the feasibility of endoscopic resection (ER) for salvage and metachronous lesions following chemoradiotherapy (CRT) and radiotherapy (RT) for laryngopharyngeal cancer.

Methods: Consecutive patients who underwent ER for superficial laryngopharyngeal cancer between March 2005 and September 2022 were retrospectively reviewed and stratified into salvage (16 patients, 16 lesions), metachronous (18 patients, 27 lesions), and naïve RT (217 patients, 306 lesions) groups. Salvage lesions were residual or local recurrent after CRT, and metachronous lesions were second primary lesions in the irradiated field following complete response.

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Objective: A newly launched endoscopy system (EVIS X1, CV-1500; Olympus) is equipped with texture and color enhancement imaging (TXI). We aimed to investigate the efficacy of TXI for the visibility and diagnostic accuracy of non-polypoid colorectal lesions.

Methods: We examined 100 non-polypoid lesions in 42 patients from the same position, angle, and distance of the view in three modes: white light imaging (WLI), narrow-band imaging (NBI), and TXI.

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Article Synopsis
  • Tip-in endoscopic mucosal resection (EMR) is effective for removing large colorectal neoplasms, but the capabilities of non-experts in performing this technique had not been studied prior to this research.
  • A study involving 597 colorectal neoplasms revealed that, while non-experts initially had lower success rates for en bloc and R0 resections, their performance improved with more experience, particularly after completing over 10 cases.
  • Factors hindering successful en bloc resections included non-polypoid lesion shapes, underlying folds in the lesions, non-lifting signs, and non-expert status with limited experience, yet the study concluded that overall outcomes by non-experts were still favorable.
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Gastrointestinal stromal tumors surrounding the esophagogastric junction are often challenging to resect, with no consensus regarding the optimal surgical technique. Here in, we present a case of concurrent gastric cancer in the antrum and gastrointestinal stromal tumors adjacent to the esophagogastric junction. The patient underwent simultaneous distal gastrectomy and local resection assisted by a surgical robot, avoiding the need for total gastrectomy.

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Several cases have been reported that suggest the efficacy of gel immersion endoscopic mucosal resection (GI-EMR) for gastric neoplasms. However, no study has evaluated treatment outcomes of GI-EMR for gastric neoplasms. This study aimed to investigate the efficacy and safety of GI-EMR for early gastric neoplasms.

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  • Computer-aided detection (CADe) systems improve polyp detection during colonoscopy but suffer from issues with false positives (FPs), which can distract endoscopists.
  • In a study comparing videos from before and after a CADe update, researchers found that the update significantly reduced the number of FPs and the time spent addressing them, while maintaining a stable true positive rate for polyp detection.
  • The findings suggest that the CADe update could ease the workload for endoscopists without compromising their ability to detect actual polyps.
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Background And Aim: Hot snare polypectomy using blend or coagulation current is widely used; however, it causes deeper tissue heat injury, leading to adverse events. We hypothesized that hot polypectomy using low-power pure cut current (PureCut, effect 1 10 W) could reduce deeper tissue heat injury. We conducted animal experiments to evaluate the deeper tissue heat injury and conducted a prospective clinical study to examine its cutting ability.

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Previous transient absorption spectroscopy (TAS) hinted at an exceptionally rapid geminate recombination process in charge transfer reactions involving OH or OD ions in liquid water and CHO ions in liquid methanol. However, a comprehensive investigation of these dynamics using TAS has been hindered by the technical challenges stemming from the ultrafast spectral shift that spans a wide wavelength range from the mid-infrared to the visible on the subpicosecond time scale. To address these challenges, we have employed ultraviolet time-resolved photoelectron spectroscopy of aqueous solutions, enabling us to observe and analyze the complete dynamics, including electron detachment, solvation, and geminate recombination.

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Article Synopsis
  • The study investigates the outcomes of endoscopic resection (ER) for submucosally invasive colorectal cancer (CRC) with a focus on vertical margin involvement and its implications for lymph node metastasis.
  • Researchers analyzed 395 cases from 2008 to 2020, finding that 21.5% had vertical incomplete ER, with significant rates of residual tumors and lymph node metastasis observed in this group.
  • The results emphasize the increased risks associated with vertical incomplete ER, highlighting the need for careful assessment and potential additional surgery to address residual tumors and lymph node involvement.
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  • The study investigates whether patients with esophageal squamous cell carcinoma (ESCC) who have positive or unclear vertical margins after endoscopic submucosal dissection (ESD) should receive additional treatment.
  • It analyzed patients treated from 2006 to 2018 with focus on those diagnosed with intralesional damage, evaluating the local recurrence risk after ESD.
  • The findings showed no local recurrences among the evaluated patients (0%), suggesting that follow-up without further treatment may be an acceptable approach even when intralesional damage occurs.
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  • - The study investigates how many needle passes during endoscopic ultrasound-guided tissue acquisition (EUS-TA) are needed to obtain optimal tumor samples for comprehensive genomic profiling (CACGP).
  • - It found that using a 22-gauge needle, the acquisition rate of ideal samples increased with more passes, being 100% at four passes, while the 19-gauge needle showed no significant correlation across passes.
  • - Successful analysis for CACGP was significantly higher with ideal samples compared to suboptimal ones, leading to the conclusion that the optimal needle pass numbers are four for 22-G and one to two for 19-G needles.
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Germline double heterozygosity (GDH) is rarely reported in cases of inherited cancer syndromes, and GDH of a mismatch repair gene and BRCA has never been reported in Japan. Nonetheless, the current report demonstrates a case of ovarian mucinous adenocarcinoma with initiated Lynch syndrome (LS)-related surveillance because of a known germline MSH2 variant. Six and a half years after oophorectomy, multiple tumors developed in the patient's lungs, bones, and lymph nodes, and histology results confirmed mucinous adenocarcinoma.

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Underwater endoscopic mucosal resection (UEMR) has become a popular endoscopic resection method for large colorectal neoplasms. However, visualization can be poor during UEMR due to the presence of intestinal fluid. Gel immersion endoscopic mucosal resection (GIEMR), using a specially developed gel (Viscoclear, Otsuka Pharmaceutical Factory, Tokushima, Japan), can improve the visual field.

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Article Synopsis
  • Time-resolved photoelectron spectroscopy (TRPES) allows scientists to observe rapid electronic processes in solutions, with extreme ultraviolet (EUV) pulses providing a broad ionization of solutes but overwhelming signals from solvents.
  • Using ultraviolet (UV) probe pulses instead offers better signal-to-noise for detecting excited solutes, but it faces challenges from spectral distortions due to various interactions in liquids.
  • This study validates a previously proposed spectral retrieval (SR) method for analyzing UV-TRPES data by comparing it with EUV-TRPES, confirming electron binding energies for solvated electrons and estimating energy gaps at the gas-liquid interface for different solvents like water and methanol.
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We report ultrafast extreme ultraviolet photoelectron spectroscopy of 6-methyluracil (6mUra) and 5-fluorouracil (5FUra) in the gas phase and 6mUra and 5-fluorouridine in an aqueous environment. In the gas phase, internal conversion (IC) occurs from ππ* to nπ* states in tens of femtoseconds, followed by intersystem crossing to the ππ* state in several picoseconds. In an aqueous solution, 6mUra undergoes IC almost exclusively to the ground state (S) in about 100 fs, which is essentially the same process as that for unsubstituted uracil, but much faster than that for thymine (5-methyluracil).

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Background And Aims: Because endoscopic submucosal dissection (ESD) for early gastric cancer (EGC) preserves the entire stomach, missed gastric cancers (MGCs) are often found in the remaining gastric mucosa. However, the endoscopic causes of MGCs remain unclear. Therefore, we aimed to elucidate the endoscopic causes and characteristics of MGCs after ESD.

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-Stilbene (-St) is a well-known benchmark system for - photoisomerization. -St also produces 4a,4b-dihydrophenanthrene (DHP) in solution with a quantum yield of less than 0.19.

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Ultrafast electronic relaxation of nucleobases from ππ* states to the ground state (S) is considered essential for the photostability of DNA. However, transient absorption spectroscopy (TAS) has indicated that some nucleobases in aqueous solutions create long-lived nπ*/ππ* dark states from the ππ* states with a high quantum yield of 0.4-0.

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Charge transfer reactions from I to solvent water, methanol, and ethanol were studied using extreme ultraviolet time-resolved photoelectron spectroscopy (EUV-TRPES). This technique eliminates spectral broadening, previously seen in UV-TRPES, caused by electron inelastic scattering in liquids, and enables clear observation of the temporal evolution of the spectral shape. The peak position, width, and intensity of the electron binding energy distribution indicate electron detachment and subsequent solvation and thermalization processes.

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Objectives: Extension of adenocarcinoma of the esophagogastric junction under the squamous epithelium may lead to errors when determining lateral margins. However, the characteristics of subsquamous extension are unclear. Herein, we evaluated the prevalence and characteristics of subsquamous extension of adenocarcinoma of the esophagogastric junction and the diagnostic performance of endoscopy for this condition.

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Objectives: Colonoscopy with adenomatous polypectomy reduces the incidence and mortality of colorectal cancer. We introduced a strategy of removing all neoplastic polyps in single-session out-patient colonoscopy using cold polypectomy. We aimed to investigate the achievement of single-session complete removal rate of detected colorectal polyps in clinical practice.

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