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Background/Aims: Using an appropriate guidewire can increase the success rate of selective cannulation in endoscopic retrograde cholangiopancreatography. The purpose of this technical study was to investigate the characteristics of each guidewire type and to evaluate its efficiency and rapidity of insertion. Methods: We conducted a three-point bending test using a universal testing machine to investigate the flexibility and bending features of each guidewire. 3D-printed silicone tubes with various types of stricture and a hand-made biliary tree silicone model with sixstranded intrahepatic ducts were used to evaluate the success rate and insertion time of each guidewire. Results: In the three-point bending test, the characteristics of each guidewire were classified. We found that the bending strengths and times were independent of shaft thickness. Using two in vitro biliary duct models, we determined that the success rate and total insertion time were better for guidewires with a resilient shaft and angled tip than for other types of guidewires (p<0.001). Although thickness of the guidewire affected the success rate (p<0.05), it did not affect the total insertion time (p≥0.05). Conclusions: Among several types of guidewire, some factors (resilient shaft, highly flexible, and angled tip) appeared to be associated with the efficiency and rapidity of the guidewire insertion. [ABSTRACT FROM AUTHOR]

Background: To overcome duodenobiliary reflux induced by biliary stents, antireflux valve (ARV) biliary stents have been developed and showed improvement in stent patency. However, negative study results have also been reported because stent patency may be decreased by the malfunction of ARV itself. Given such mixed results, the true efficacy of ARV remains unknown and the mechanism of its dysfunction needs to be clearly elucidated. The aim of this study was to investigate the exact mechanism of ARV dysfunction using in vitro phantom models.Methods: Two experimental models were designed to evaluate two important environmental factors suspected to cause ARV malfunction, i.e. bile flow and pH. Three types of ARV metal stents from different companies were used for the experiments: a funnel type ARV, a windsock type ARV, and a wine glass-shaped ARV. Ten stents of each type were tested (five stents in the bile flow phantom model, and another five stents in the duodenal pH environmental model). To determine ARV malfunction, ARV-induced flow resistance was measured using a custom-made testing device. All stents from the two models were removed every 2 weeks for 12 weeks after stent insertion and were evaluated on morphological and functional changes of the ARV.Results: Only ARV of wine glass-shaped ARV was morphologically changed due to silicone bond detachment in the bile flow model. All types of ARV were morphologically changed in the pH model. The morphological changes of ARV influenced the flow resistance. The antegrade pressure gradients were increased over time in the pH model (p < 0.05).Conclusions: Morphological change of the ARVs may induce dysfunction of ARV metal stents, which is mainly due to duodenal pH environment. In the future, development of new ARV that is not affected by duodenal environmental factors can be expected to improve stent patency. [ABSTRACT FROM AUTHOR]

Background/Aims: This study aimed to evaluate the diagnostic role of low serum amylase and lipase values in the detection of chronic pancreatitis. Methods: Patients underwent endoscopic retrograde cholangiopancreatography and were diagnosed with non-calcific chronic pancreatitis (NCCP; n=99) and calcific chronic pancreatitis (CCP; n=112). Patient serum amylase and lipase values were compared with those of healthy controls (H; n=170). Results: The median serum amylase (normal range, 19 to 86 U/L) and lipase values (7 to 59 U/L) (P25-P75) were 47.0 (39.8 to 55.3) and 25.0 (18.0 to 35.0) for H, 34.0 (24.5 to 49.0) and 19.0 (9.0 to 30.0) for NCCP, and 30.0 (20.0 to 40.8) and 10.0 (3.0 to 19.0) for CCP, respectively. The cutoff values with the highest diagnostic accuracy for discriminating NCCP from H were 40 U/L for amylase and 20 U/L for lipase, respectively, and for CCP from H were 38 U/L for amylase and 15 U/L for lipase, respectively. For the diagnosis of NCCP with a criterion of serum amylase <40 and lipase <20 U/L, the sensitivity, specificity, positive predictive value, and negative predictive values were 37.4%, 88.8%, 66.1%, and 70.9%, respectively. Conclusions: Serum amylase and/or lipase levels below the normal serum range are highly specific for chronic pancreatitis patients. Clinicians should not ignore low serum pancreatic enzyme values. [ABSTRACT FROM AUTHOR]

Background and study aims Complete stone removal from the main pancreatic duct might not be achieved in all patients with obstructive chronic calcific pancreatitis. We report our results for endoscopic dorsal pancreatic duct (DPD) bypass of obstructing stones in the ventral pancreatic duct (VPD). Patients and methods 16 patients with obstructive chronic calcific pancreatitis were treated with a DPD bypass. Clinical success was defined as significant pain relief and no hospital admissions for pain management during the ongoing treatment period. Results Among 16 patients meeting entry criteria, 10 (62.5 %) had a history of unsuccessful endoscopic therapy, and 8 had failed extracorporeal shockwave lithotripsy (ESWL). Clinical success was achieved in 12 patients (75 %). Among these responders, 10 patients (83.3 %) had markedly improved or complete pain relief after the first stent placement, which persisted throughout the follow-up period; 11 patients (91.7 %) were able to discontinue their daily analgesics. Conclusions In selected patients with obstructive chronic calcific pancreatitis, the DPD bypass may be considered as a rescue endoscopic therapy, potentially obviating the need for surgery when standard endoscopic methods and ESWL fail. [ABSTRACT FROM AUTHOR]

Background/Aims: The efforts to improve biliary plastic stents (PSs) for decreasing biofilm formation and overcome short patency time have been continued. The aim of this study is to evaluate the effect of advanced hydrophilic coating for patency and biodurability of PS. Methods: Using an in vitro bile flow phantom model, we compared patency between prototype PS with hydrophilic coating (PS+HC) and prototype PS without hydrophilic coating (PS-HC). We performed an analysis of the degree of luminal narrowing by microscopic examination. Using an in vivo swine bile duct dilation model made by endoscopic papillary closure and stent insertion, we evaluated biodurability of hydrophilic coating. Results: In the phantom model, PS+HC showed less biofilm formation and luminal narrowing than PS-HC at 8 weeks (p<0.05). A total of 31 stents were inserted into the dilated bile duct of seven swine models, and 24 stents were successfully retrieved 8 weeks later. There was no statistical difference of stent patency between the polyethylene PS+HC and the polyurethane PS+HC. The biodurability of hydrophilic coating was sustained up to 8 weeks, when assessing the coating layer by scanning electron microscopy examination. Conclusions: Advanced hydrophilic coating technology may extend the patency of PS compared to uncoated PS. [ABSTRACT FROM AUTHOR]

Biliary stenting via endoscopic retrograde cholangiopancreatography has greatly improved the quality of patient care over the last 30 years. Plastic stent occlusion limits the life span of such stents. Attempts to improve plastic stent patency duration have mostly failed. Metal stents (self-expandable metal stents [SEMSs]) have therefore replaced plastic stents, especially for malignant biliary strictures. SEMS are at least 10 times more expensive than plastic stents. In this focused review, we will discuss basic mechanisms of plastic stent occlusion, along with a systematic summary of previous efforts and related studies to improve stent patency and potential new techniques to overcome existing limitations. [ABSTRACT FROM AUTHOR]

Esophageal duplication (ED) is rarely diagnosed in adults and is usually asymptomatic. Especially, ED that is connected to the esophagus through a tubular communication and combined with bronchoesophageal fistula (BEF) is extremely rare and has never been reported in the English literature. This condition is very difficult to diagnose. Although some combinations of several modalities, such as upper gastrointestinal endoscopy, esophagography, computed tomography, magnetic resonance imaging, and endoscopic ultrasonography, can be used for the diagnosis, the results might be inconclusive. Here, we report on a patient with communicating tubular ED that was incidentally diagnosed on the basis of endoscopy and esophagography during the postoperational evaluation of BEF. [ABSTRACT FROM AUTHOR]

Endoscopic submucosal dissection is recommended as an alternative therapy for early esophageal cancer. However, achieving curative resection in this procedure remains controversial since precise prediction of lymph node metastasis can be difficult. Here, we present the preliminary results of endoscopic submucosal dissection followed by concurrent chemoradiotherapy for early esophageal cancer with a high risk of lymph node metastasis. From May 2006 to January 2014, six patients underwent concurrent chemoradiotherapy after endoscopic submucosal dissection with a median follow-up period of 63 months. No complications were encountered during concurrent chemoradiotherapy. Although local recurrence did not occur in all patients, two patients were diagnosed with metachronous cancer. Overall, the survival rate was 100%. Thus, endoscopic submucosal dissection followed by concurrent chemoradiotherapy may be a feasible treatment for early esophageal cancer in patients with a high risk of lymph node metastasis. Future prospective large-scale studies are warranted to confirm our results. [ABSTRACT FROM AUTHOR]

Background/Aims: The use of a self-expandable metal stent (SEMS) is recommended for unresectable malignant biliary obstruction (MBO). Stent-related adverse events might differ according to the position of the stent through the ampulla of Vater (AOV). We retrospectively evaluated SEMS patency and adverse events according to the position of the SEMS. Methods: In total, 280 patients who underwent endoscopic SEMS placement due to malignant distal biliary obstruction were analyzed retrospectively. Suprapapillary and transpapillary SEMS insertions were performed on 51 patients and 229 patients, respectively. Results: Between the suprapapillary group (SPG) and transpapillary group (TPG), the stent patency period was not significantly different (median [95% confidence interval]: 107 days [82.3 to 131.7] vs 120 days [99.3 to 140.7], p=0.559). There was also no significant difference in the rate of adverse events. In subgroup analysis, the stent patency for an MBO located within 2 cm from the AOV was found to be significantly shorter than that for an MBO located more than 2 cm from the AOV in the SPG (64 days [0 to 160.4] vs 127 days [82.0 to 171.9], p<0.001) and TPG (87 days [52.5 to 121.5] vs 130 [97.0 to 162.9], p<0.001). Patients with an MBO located within 2 cm from the AOV in both groups had a higher percentage of duodenal invasion (SPG: 40.0% vs 4.9%, p=0.002; TPG: 28.6% vs 2.9%, p<0.001) than patients with an MBO located more than 2 cm from the AOV. Conclusions: The SPG and TPG showed similar results in terms of stent patency and rate of adverse events. However, patients with an MBO located within 2 cm from the AOV had a higher percentage of duodenal invasion with shorter stent patency than those with an MBO located more than 2 cm from the AOV, regardless of stent position. [ABSTRACT FROM AUTHOR]

Complex electronic phases in strongly correlated electron systems are manifested by broken symmetries in the low-energy electronic states. Some mysterious phases, however, exhibit intriguing energy gap opening without an apparent signature of symmetry breaking (e.g., high-TC cuprates and heavy fermion superconductors). Here, we report an unconventional gap opening in a heterostructured, iron-based superconductor Sr2VO3FeAs across a phase transition at T0 ~150 K. Using angle-resolved photoemission spectroscopy, we identify that a fully isotropic gap opens selectively on one of the Fermi surfaces with finite warping along the interlayer direction. This band selectivity is incompatible with conventional gap opening mechanisms associated with symmetry breaking. These findings, together with the unusual field-dependent magnetoresistance, suggest that the Kondo-type proximity coupling of itinerant Fe electrons to localized V spin plays a role in stabilizing the exotic phase, which may serve as a distinct precursor state for unconventional superconductivity. [ABSTRACT FROM AUTHOR]

The article presents case study of a 74-year-old man diagnosed with pancreatic head cancer with biliary obstruction, who received a plastic stent placement for biliary drainage. After 4 months, he developed melena and jaundice and computed tomography scan revealed suspicious active bleeding from the right hepatic artery from the invasion of the proximal flap of the stent.

Background/Aims: Colonoscopic perforations have been managed with exploratory laparotomy, and have resulted in some morbidity and mortality. Recently, laparoscopic surgery is commonly performed for this purpose. The aim of this study was to compare the outcomes of several management strategies for iatrogenic colonoscopic perforations. Methods: We retrospectively reviewed the medical records of patients who had been treated for colonoscopic perforation between January 2004 and April 2013 at CHA Bundang Medical Center in Korea. Results: A total of 41 patients with colonoscopic perforation were enrolled. Twenty patients underwent conservative management with a success rate of 90%. Surgical management was performed in 23 patients including two patients who were converted to surgical management after the failure of the initial conservative management. Among 14 patients who underwent surgery at 8 hours after the perforation, there was no considerable difference in adverse outcomes between the laparotomy group and the laparoscopic surgery group. The medical costs and claim rate were 1.45 and 1.87 times greater in the exploratory laparotomy group, respectively. Conclusions: Conservative management of colonoscopic perforation could be an option for patients without overt symptoms of peritonitis or with a small defect size. If surgical management is required, laparoscopic surgery may be considered as the initial procedure even with a delayed diagnosis. [ABSTRACT FROM AUTHOR]

Background/Aims: Various anatomical features of the biliary tree affect ability to remove difficult common bile duct (CBD) stones. In this study, we evaluated the clinical characteristics and outcomes of the endoscopic treatment of stones in stemware-shaped CBDs. Methods: Thirty-four patients with a stone and a stemware-shaped CBD who were treated at different tertiary referral centers from January 2008 to December 2012 were studied retrospectively. When stone removal failed, percutaneous or direct peroral cholangioscopic lithotripsy, endoscopic retrograde biliary drainage, or surgery was performed as a second-line procedure. Results: The overall success rate of the first-line procedure was 41.2%. Five of the 34 patients (14.7%) experienced procedure-related complications. No procedure-related mortality occurred. Mechanical lithotripsy was required to completely remove stones in 13 patients (38.2%). Conversion to a second-line procedure was required in 20 patients (58.8%). Mechanical lithotripsy was needed in 75% and 66.7% of those with a stone size of <1 cm or ≥1 cm, respectively. Stone recurrence occurred in two patients (9.1%) after 6 months and 27 months, respectively. Conclusions: The endoscopic treatment of stones in a stemware-shaped CBD is challenging. The careful assessment of difficult CBD stones is required before endoscopic procedures. [ABSTRACT FROM AUTHOR]

This paper proposes state-of-charge (SOC) estimation algorithms that utilize a filtered battery terminal voltage without measuring the current. These methods extract an estimated open-circuit voltage (OCV) or current from the battery terminal voltage through equivalent circuit model-based filters, which streamlines the estimation process. In the methods, the OCV values derived from the corresponding SOCs are used to extract the filter coefficient for ease of implementation. The relationship between the model's accuracy and estimation performance is investigated, and the variation of the SOC estimation error due to the model parameter tolerance is also derived by the Monte Carlo simulation tool to confirm the practicality of the method. To validate the performance of the proposed approach, a parameter extraction profile and an actual mobile phone profile are applied to a 2.6 Ah prismatic Li-ion battery. The experimental results show the feasibility of the proposed SOC estimation algorithm to within a 5% SOC estimation error. [ABSTRACT FROM AUTHOR]

Background/Aims: This study assessed the efficacy of a rifaximin plus levofloxacin-based rescue regimen in patients that had failed both triple and quadruple standard regimens for the eradication of Helicobacter pylori. Methods: We treated patients for H. pylori between August 2009 and April 2011. The triple regimen consisted of combined treatment with amoxicillin, clarithromycin, and pantoprazole for 1 week. For failed cases, a quadruple regimen of tetracycline, metronidazole, bismuth dicitrate, and lansoprazole for 1 week was administered. The rescue regimen for persistently refractory cases was rifaximin 200 mg t.i.d., levofloxacin 500 mg q.d., and lansoprazole 15 mg b.i.d. for 1 week. Results: In total, 482 patients were enrolled in this study. The eradication rates associated with the first and second regimens were 58% and 60%, respectively. Forty-seven out of 58 patients who failed with the second-line regimen received rifaximin plus levofloxacin-based third-line therapy. The eradication rate for the third regimen was 65%. The cumulative eradication rates were 58%, 85%, and 96% for each regimen, respectively. Conclusions: A rifaximin plus levofloxacin-based regimen could be an alternative rescue therapy in patients with resistance to both triple and quadruple regimens for the eradication of H. pylori. [ABSTRACT FROM AUTHOR]

Background and Aim: Signal transducers and activators of transcription (STAT) behave as signal transducers in the cytoplasm and as transcription factors in the nucleus. In the current study, we analyzed the immunohistochemical staining patterns of gastrectomy tissue specimens. We investigated the expression of STAT3 and STAT5 and estimated the relationship between STAT and cancer prognosis. Methods: One hundred patients who underwent gastrectomy due to gastric adenocarcinoma at Bundang CHA hospital between January 2000 and May 2005 were studied. Immunohistochemistry was carried out using antibodies against STAT3 and STAT5. The interpretation of the immunohistochemical staining was based on the proportion of stained cells in the field: positive, > 10% stained cells; and negative, < 10% stained cells. Results: The longest diameter of tumor was 4.67 cm in the positive group and 3.76 cm in the negative group, and these results were not statistically different ( P-value = 0.112). Higher T (primary tumor) value ( P-value = 0.05), more regional lymph node invasion ( P-value = 0.008) and higher TNM staging ( P-value = 0.069) were significantly related to STAT3 positivity, but Helicobacter pylori infection or atrophic gastritis were not related. A lower survival rate was observed in the STAT3-positive group ( P-value = 0.001). The results of STAT5 were not statistically different with respect to TNM staging and survival ( P-value = 0.958). We thus report that the immunohistochemical results of STAT3 revealed a significant association with TNM staging and survival. Conclusion: We anticipate that STAT3 may be used as a molecular staging biomarker predicting poor prognosis of gastric cancer. [ABSTRACT FROM AUTHOR]

Background/Aims Biliary dyspepsia presents as biliary colic in the absence of explanatory structural abnormalities. Causes include gallbladder dyskinesia, sphincter of Oddi dysfunction, biliary tract sensitivity, microscopic sludges, and duodenal hypersensitivity. However, no consensus treatment guideline exists for biliary dyspepsia. We investigated the effects of medical treatments on biliary dyspepsia. Methods We retrospectively reviewed the electronic medical records of 414 patients who had biliary pain and underwent cholescintigraphy from 2008 to 2018. We enrolled patients who received litholytic agents and underwent follow-up scans after medical treatment. We divided the patients into the GD group (biliary dyspepsia with reduced gallbladder ejection fraction [GBEF]) and the NGD group (biliary dyspepsia with normal GBEF). We compared pre- and post-treatment GBEF and symptoms. Results Of the 57 patients enrolled, 40 patients (70.2%) had significant GBEF improvement post-treatment, ranging from 34.4%±22.6% to 53.8%±26.8% (p<0.001). Fifty-two patients (91.2%) experienced significant symptom improvement (p<0.001). In the GD group (n=35), the GBEF improved significantly in 28 (80.0%) patients (range, 19.5%±11.0% to 47.9%±27.3%; p<0.001). In the NGD group (n=22), the GBEF improved in 12 (54.5%) patients, which was not significant (p=0.401). Most patients (97.1% in the GD group and 81.8% in the NGD group) had improved symptoms (p<0.001). No severe complication was reported during the treatment period. Conclusions Litholytic agents improved biliary colic in patients with biliary dyspepsia. Therefore, these agents present an alternative treatment modality for biliary dyspepsia with or without gallbladder dyskinesia. Notably, biliary colic in patients with gallbladder dyskinesia resolved after normalization of the GBEF. Further prospective and large-scale mechanistic studies are warranted. [ABSTRACT FROM AUTHOR]