Publications by authors named "Chang-Il Kwon"

87 Publications

Band-selective gap opening by a -symmetric order in a proximity-coupled heterostructure SrVOFeAs.

Proc Natl Acad Sci U S A 2021 Nov;118(47)

Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea;

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- cuprates and heavy fermion superconductors). Here, we report an unconventional gap opening in a heterostructured, iron-based superconductor SrVOFeAs across a phase transition at ∼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.
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http://dx.doi.org/10.1073/pnas.2105190118DOI Listing
November 2021

Real-world efficacy and safety of nab-paclitaxel plus gemcitabine-cisplatin in patients with advanced biliary tract cancers: a multicenter retrospective analysis.

Ther Adv Med Oncol 2021 7;13:17588359211035983. Epub 2021 Aug 7.

Department of Medical Oncology, CHA Bundang Medical Center, CHA University School of Medicine, 59 Yatap-ro, Bundang-gu, Seongnam 13496, Republic of Korea.

Background: A recent phase II trial reported prolonged survival in patients with advanced biliary tract cancer (BTC) following treatment with nab-paclitaxel plus gemcitabine-cisplatin (Gem/Cis/nab-P). We aimed to evaluate the clinical outcomes of Gem/Cis/nab-P in Asian patients with advanced BTC in a real-world setting.

Methods: We reviewed the data of patients who received Gem/Cis/nab-P for the management of advanced BTC between September 2019 and April 2021 at four institutes in Korea. Patients were classified into the Gem/Cis/nab-P and nab-P addition groups depending on the starting point of nab-P administration.

Results: A total of 178 patients treated with Gem/Cis/nab-P were included in the study. Of these, 43.8% had intrahepatic cholangiocarcinoma (CCA), 34.8% had extrahepatic CCA, and 21.3% had gall bladder cancer. A total of 117 (65.7%) patients received Gem/Cis/nab-P as the first-line treatment, while 61 (34.3%) were treated with gemcitabine-cisplatin-based chemotherapy followed by nab-P addition. The objective response rate (ORR) and disease control rate in all patients were 42.1% and 84.8%, respectively. The ORR in the Gem/Cis/nab-P group was 47.9%, while that in the nab-P addition group was 31.1%. The median progression-free survival and overall survival were 8.5 months [95% confidence interval (CI), 6.9-10.1] and 14.6 months (95% CI, 10.2-19.0), respectively. In patients who received Gem/Cis/nab-P as initial treatment, the median PFS was 9.4 months (95% CI, 7.9-10.9) and the median OS was not-reached (95% CI, not available). Anemia ( = 42, 23.6%), neutropenia ( = 40, 22.5%), and thrombocytopenia ( = 16, 9.0%) were the most common grade 3-4 toxicities. A total of 20 patients (11.2%) had conversions from unresectable to resectable disease and underwent surgery with curative intent.

Conclusion: Gem/Cis/nab-P showed favorable real-life efficacy and safety outcomes in Korean patients with advanced BTC, which was consistent with the phase II trial outcomes.
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http://dx.doi.org/10.1177/17588359211035983DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8358499PMC
August 2021

Clinical utility of methionyl-tRNA synthetase 1 immunostaining in cytologic brushings of indeterminate biliary strictures: a multicenter prospective study.

Gastrointest Endosc 2021 10 6;94(4):733-741.e4. Epub 2021 May 6.

Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea.

Background And Aims: Endobiliary brushings are routinely used in the diagnosis, treatment, and prognostication of biliary strictures. However, standard Papanicolaou (Pap) staining has a low sensitivity in this setting, and the accuracy of brush cytology has not been established for indeterminate strictures. We therefore evaluated the diagnostic merit of methionyl-transfer RNA synthetase 1 (MARS1) immunofluorescence (IF) staining in such cytologic specimens.

Methods: During ERCP, endobiliary brushings were obtained from patients with extrahepatic biliary strictures prospectively enrolled at 6 tertiary hospitals. Using liquid-based cytologic preparations of these samples, we performed Pap and MARS1 IF staining.

Results: In total, 240 patients were eligible; of these, we compared the Pap and MARS1 IF staining results of 218 (malignant, 157; benign, 61). By conventional Pap staining, the diagnoses were distributed as follows: malignant, 55; suspicious of malignancy, 60; atypical, 45; negative for malignancy, 58. MARS1 IF staining was strongly positive in malignant biliary stricture but not so in specimens negative for malignancy. The diagnostic parameters (sensitivity, specificity, positive predictive value, negative predictive value, and accuracy) of the MARS1 IF (93.6%, 96.7%, 98.7%, 85.5%, and 94.5%, respectively) and conventional Pap (73.2%, 100%, 100%, 59.2%, and 80.7%, respectively) staining methods differed significantly (P < .0001).

Conclusions: The high sensitivity and accuracy of MARS1 IF staining enabled the detection of malignancy in patients with biliary strictures. Further prospective studies are needed to validate our findings. (Clinical trial registration number: NCT03708445.).
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http://dx.doi.org/10.1016/j.gie.2021.04.026DOI Listing
October 2021

Mechanical properties and degradation process of biliary self-expandable biodegradable stents.

Dig Endosc 2021 Nov 21;33(7):1158-1169. Epub 2021 Jan 21.

Division of Gastroenterology, Department of Internal Medicine, Inha University College of Medicine, T2B Infrastructure Center for Digestive Disorders, Incheon, Korea.

Objectives: The clinical outcomes and prevalence of adverse events associated with biliary biodegradable stents (BS) can differ according to degradation process and time. The aim of this study was to observe the degradation process and time of different BS prototypes, and to evaluate sequential changes in their mechanical properties.

Methods: Using an in vitro bile flow phantom model, we compared degradation time, radial force changes, and morphologic changes among four different BS prototypes: polydioxanone (PDO) BS, polyglycolide (PGA) BS, polydioxanone/poly-l-lactic acid (PDO/PLLA) sheath-core BS, and polydioxaone/magnesium (PDO/Mg) sheath-core BS. Using an in vivo swine bile duct dilation model, we performed a direct peroral cholangioscopy (DPOC) examination to observe the biodegradation process and related adverse events at regular intervals.

Results: In the bile flow phantom model, the PGA BS and PDO/Mg BS prototypes showed rapid radial force reduction and morphological changes and complete degradation within six weeks. PDO/PLLA BS maintained high radial force and kept their original shape for longer than the PDO BS, up to 16 weeks. A total of 24 BS were inserted into the dilated bile ducts of 12 swine. In this animal model, DPOC examination revealed that PDO BS and PDO/PLLA BS maintained their original shapes for approximately 12 weeks, but PDO BS showed a greater degree of fragmentation and induced biliary stones and bile duct obstruction.

Conclusion: Our results showed that PDO/PLLA BS maintained their original shape and radial force for a relatively long time and minimized adverse events.
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http://dx.doi.org/10.1111/den.13916DOI Listing
November 2021

What is the better surgical treatment option for recurrent common bile duct stones?

Ann Surg Treat Res 2020 Dec 26;99(6):329-336. Epub 2020 Nov 26.

Digestive Disease Center, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Korea.

Purpose: Repeating endoscopic retrograde cholangiopancreatography (ERCP) in patients with recurrent common bile duct (CBD) stones is problematic in many ways. Choledochoduodenostomy (CDS) and choledochojejunostomy (CJS) are 2 surgical treatment options for recurrent CBD stones, and each has different advantages and disadvantages. The aim of this study was to compare the 2 surgical options in terms of the recurrence rate of CBD stones after surgical treatment.

Methods: This retrospective multicenter study included all patients who underwent surgical treatment due to recurrent CBD stones that were not effectively controlled by medical treatment and repeated ERCP between January 2006 and March 2015. We collected data from chart reviews and medical records. A recurrent CBD stone was defined as a stone found 6 months after the complete removal of a CBD stone by ERCP. Patients who underwent surgery for other reasons were excluded.

Results: A total of 27 patients were enrolled in this study. Six patients underwent CDS, and 21 patients underwent CJS for the rescue treatment of recurrent CBD stones. The median follow-up duration was 290 (180-1,975) days in the CDS group and 1,474 (180-6,560) days in the CJS group (P = 0.065). The postoperative complications were similar and tolerable in both groups (intestinal obstruction; 2 of 27, 7.4%; 1 in each group). CBD stones recurred in 4 patients after CDS (4 of 6, 66.7%), and 3 patients after CJS (3 of 21, 14.3%) (P = 0.010).

Conclusion: CJS may be a better surgical option than CDS for preventing further stone recurrence in patients with recurrent CBD stones.
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http://dx.doi.org/10.4174/astr.2020.99.6.329DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7704274PMC
December 2020

Pseudoaneurysmal Rupture of the Hepatic Artery Caused by a Biliary Plastic Stent.

Am J Gastroenterol 2021 07;116(7):1371

Digestive Disease Center, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Korea.

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http://dx.doi.org/10.14309/ajg.0000000000000982DOI Listing
July 2021

Clinical outcome of endoscopic retrograde cholangiopancreatography for choledocholithiasis in end-stage renal disease patients on hemodialysis.

Turk J Gastroenterol 2020 07;31(7):538-546

Department of Internal Medicine, Inha University School of Medicine, Incheon, South Korea.

Background/aims: Endoscopic retrograde cholangiopancreatography (ERCP) is used as a curative method for choledocholithiasis, but little is known about ERCP for patients with end-stage renal disease (ESRD) on hemodialysis (HD). The aim of the current study was to evaluate the efficacy and safety of ERCP for patients with ESRD on HD and to identify the risk factors of ERCP-related bleeding.

Materials And Methods: The medical records of 61 ESRD patients with choledocholithiasis who underwent ERCP were retrospectively investigated with respect to successful bile duct stone removal and procedure-related adverse events such as pancreatitis, bleeding, and cholangitis.

Results: For the study subjects, the overall stone removal success rate was 96.7%, and the overall ERCP-related adverse event rate was 21.3% (pancreatitis, 4.9%; bleeding, 13.1%; cholangitis, 6.6%). Endoscopic sphincterotomy (EST) was found to be associated with hemorrhage (p=0.02), and the occurrence of hemorrhage in patients who underwent EST with or without endoscopic papillary balloon dilation (EPBD) was significantly higher than that in patients who underwent EPBD alone (Odds ratio 1.27, 95% confidence interval 1.075-1.493, p=0.02).

Conclusion: ERCP for ESRD patients was found to be feasible and safe. However, EST was significantly related to hemorrhagic events. EPBD reduced the risk of hemorrhage and was as effective as EST in terms of stone removal.
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http://dx.doi.org/10.5152/tjg.2020.19521DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7480200PMC
July 2020

Litholytic agents as an alternative treatment modality in patients with biliary dyspepsia.

Medicine (Baltimore) 2020 Aug;99(34):e21698

Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul.

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.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.Among 57 patients enrolled, 40 (70.2%) patients had significant GBEF improvement post-treatment, ranging from 34.4 ± 22.6% to 53.8 ± 26.8% (P < .001). In GD group (n = 35), 28 patients had GBEF improvement after medical treatment, and value of GBEF significantly improved from 19.5 ± 11.0 to 47.9 ± 27.3% (P < .001). In NGD group (n = 22), 12 patients had GBEF improvement after medical treatment, but value of GBEF did not have significant change. Most patients (97.1% in GD group and 81.8% in NGD group) had improved symptoms after medical treatment. No severe complication was reported during treatment period.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.
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http://dx.doi.org/10.1097/MD.0000000000021698DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7447440PMC
August 2020

Can prophylactic argon plasma coagulation reduce delayed post-papillectomy bleeding? A prospective multicenter trial.

J Gastroenterol Hepatol 2021 Feb 29;36(2):467-473. Epub 2020 Jul 29.

Division of Gastroenterology, Department of Internal Medicine, College of Medicine, Soonchunhyang University, Cheonan, Republic of Korea.

Background And Aim: Endoscopic post-papillectomy bleeding occurs in 3% to 20% of the cases, and delayed bleeding is also problematic. However, there is no consensus on how to reduce delayed post-papillectomy bleeding. The aim of this study was to evaluate the efficacy of prophylactic argon plasma coagulation (APC) to minimize delayed bleeding and reduce the persistence of residual tumors after endoscopic papillectomy.

Methods: In a prospective pilot study of patients with benign ampullary tumors, the prophylactic APC group underwent APC at the resection margin following a conventional snaring papillectomy. Then, 24 h later after the papillectomy, all patients underwent a follow-up duodenoscopy to identify post-papillectomy bleeding and were followed up until 12 months. The main outcomes were the delayed (≥24 h) post-papillectomy bleeding rate and the tumor persistence rate.

Results: The delayed post-papillectomy bleeding rate was 30.8% (8/26) in the prophylactic APC group and 21.4% (6/28) in the non-APC group (P = 0.434). The post-procedure pancreatitis rates were 23.1% (6/26) and 35.7% (10/28), respectively (P = 0.310). The rate of tumor persistence did not differ between the two groups at 1 month (12.5% vs 7.4%, P = 0.656), 3 months (4.2% vs 3.7%, P = 1.00), 6 months (8.3% vs 3.7%, P = 0.595), and 12 months (0% vs 3.7%, P = 1.00). There were no procedure-related mortalities or serious complications.

Conclusion: Prophylactic APC may not be effective in reducing delayed post-papillectomy bleeding or remnant tumor ablation immediately after conventional papillectomy (Clinical trial registration-cris.nih.go.kr; KCT0001955).
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http://dx.doi.org/10.1111/jgh.15186DOI Listing
February 2021

Production of ERCP training model using a 3D printing technique (with video).

BMC Gastroenterol 2020 May 11;20(1):145. Epub 2020 May 11.

Research Group for Endoscopic Instruments and Stents, Korean Society of Gastrointestinal Endoscopy, Seoul, Korea.

Background: ERCP training models are very different in terms of anatomical differences, ethical issues, storage problems, realistic tactile sensation, durability and portability. There is no easy way to select an optimized model for ERCP training. If the ERCP training model could be made as a soft silicone model using 3D printing technique, it would have numerous advantages over the models presented so far. The purpose of this study was to develop an optimized ERCP training model using a 3D printing technique and to try to find ways for implementing various practical techniques.

Methods: All organ parts of this model were fabricated using silicone molding techniques with 3D printing. Especially, various anatomy of the ampulla of Vater and common bile duct (CBD) were creatively designed for different diagnostic and therapeutic procedures. In order to manufacture each of the designed organ parts with silicone, a negative part had to be newly designed to produce the molder. The negative molders were 3D printed and then injection molding was applied to obtain organ parts in silicone material. The eight different types of ampulla and CBD were repeatedly utilized and replaced to the main system as a module-type.

Results: ERCP training silicone model using 3D technique was semi-permanently used to repeat various ERCP procedures. All ERCP procedures using this model could be observed by real-time fluoroscopic examination as well as endoscopic examination simultaneously. Using different ampulla and CBD modules, basic biliary cannulation, difficult cannulation, stone extraction, mechanical lithotripsy, metal stent insertion, plastic stent insertion, and balloon dilation were successfully and repeatedly achieved. Endoscopic sphincterotomy was also performed on a specialized ampulla using a Vienna sausage. After repeat procedures and trainings, all parts of organs including the ampulla and CBD modules were not markedly damaged or deformed.

Conclusions: We made a specialized ERCP training silicon model with 3D printing technique. This model is durable, relatively cheap and easy to make, and thus allows the users to perform various specialized ERCP techniques, which increases its chances of being a good ERCP training model.
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http://dx.doi.org/10.1186/s12876-020-01295-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7216470PMC
May 2020

Embolization of pancreatic arteriovenous malformation: A case report.

World J Clin Cases 2020 Apr;8(8):1471-1476

Department of Radiology, Dankook University Hospital, Chungcheongnam-do 31116, South Korea.

Background: Pancreatic arteriovenous malformation (AVM) is a rare disease with a number of different reported treatment methods, but there are as yet no established or definite treatments for the disease.

Case Summary: A 43-year-old man visited the hospital due to periumbilical pain. The patient underwent imaging study and laboratory testing for evaluation of cause. Pancreatic AVM associated with pancreatitis was suspected on computed tomography and magnetic resonance imaging. The patient was diagnosed with pancreatic AVM with pancreatitis on imaging study and angiography. Transcatheter arterial embolization with various embolic materials was performed. Follow-up computed tomography scan revealed progressive regression of AVM and improvement of pancreatitis. At two-year follow-up, the patient showed no recurrence of symptom or pancreatitis.

Conclusion: Transcatheter arterial embolization can be considered an effective treatment modality for selective cases of pancreatic AVM.
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http://dx.doi.org/10.12998/wjcc.v8.i8.1471DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7190961PMC
April 2020

Primary Needle-Knife Fistulotomy Versus Conventional Cannulation Method in a High-Risk Cohort of Post-Endoscopic Retrograde Cholangiopancreatography Pancreatitis.

Am J Gastroenterol 2020 04;115(4):616-624

Biostatistics Collaboration Unit, Yonsei University College of Medicine, Seoul, Korea.

Objectives: Successful biliary cannulation is a prerequisite and important component of endoscopic retrograde cholangiopancreatography, but conventional cannulation methods (CCMs) have a postendoscopic retrograde cholangiopancreatography pancreatitis (PEP) rate of 14.1% in patients at high risk for PEP. The aim of this study was to evaluate the effectiveness and safety of needle-knife fistulotomy (NKF), compared with a CCM, when used for primary biliary access in patients at high risk for developing PEP.

Methods: A total of 207 patients with one or more risk factors for PEP were prospectively enrolled. The patients were randomly allocated to one of 2 groups according to the primary biliary cannulation technique (NKF or CCM). We compared biliary cannulation success rates, cannulation and procedure times, and the incidence of adverse events, including PEP, between the groups.

Results: The mean number of PEP risk factors was similar between the groups (NKF, 2.2 ± 1.0; CCM, 2.2 ± 0.9). PEP occurred in 8 patients in the CCM group and in no patients in the NKF group (9.2% vs 0%, P < 0.001). The rates of other adverse events did not differ between the groups. The biliary cannulation success rate was high in the NKF group, but relatively low in the CCM group, possibly because of the stringent failure criteria aimed at reducing PEP. However, the mean cannulation and total procedural times were longer in the NKF group than in the CCM group.

Discussion: NKF is an effective and safe procedure to gain primary biliary access in patients at high risk for developing PEP. ClinicalTrials.gov, NCT02916199.
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http://dx.doi.org/10.14309/ajg.0000000000000480DOI Listing
April 2020

Electrical Tuning of the Excitonic Insulator Ground State of Ta_{2}NiSe_{5}.

Phys Rev Lett 2019 Nov;123(20):206401

Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Republic of Korea.

We demonstrate that the excitonic insulator ground state of Ta_{2}NiSe_{5} can be electrically controlled by electropositive surface adsorbates. Our studies utilizing angle-resolved photoemission spectroscopy reveal intriguing wave-vector-dependent deformations of the characteristic flattop valence band of this material upon potassium adsorption. The observed band deformation indicates a reduction of the single-particle band gap due to the Stark effect near the surface. The present study provides the foundation for the electrical tuning of the many-body quantum states in excitonic insulators.
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http://dx.doi.org/10.1103/PhysRevLett.123.206401DOI Listing
November 2019

Efficacy of a modified double-guidewire technique using an uneven double lumen cannula (uneven method) in patients with surgically altered gastrointestinal anatomy (with video).

Surg Endosc 2020 03 30;34(3):1432-1441. Epub 2019 Oct 30.

Department of Gastroenterology and Hepatology, Faculty of Medicine, Kindai University, 377-2 Ohno-higashi, Osaka-Sayama, 589-8511, Japan.

Background: Balloon enteroscopy-assisted endoscopic retrograde cholangiopancreatography (BE-ERCP) has been reported to be effective for patients with surgically altered gastrointestinal anatomy. However, selective biliary cannulation remains difficult in BE-ERCP. We examined the usefulness of a modified double-guidewire technique using an uneven double lumen cannula (the uneven method) for BE-ERCP in patients with surgically altered gastrointestinal anatomy.

Methods: To clarify the usefulness of the uneven method for selective biliary cannulation in BE-ERCP in comparison to the pancreatic guidewire (PGW) method, 40 patients with surgically altered gastrointestinal anatomy who underwent BE-ERCP with successful placement of a guidewire in the pancreatic duct were evaluated. The uneven method was used in 18 cases (uneven group) and the PGW method was used in the remaining 22 cases (PGW group).

Results: The technical success rate of biliary cannulation was higher in the uneven group than in the PGW group (83.3 vs. 59.0%; P = 0.165). In addition, the time to biliary cannulation were significantly shorter in the uneven group than in the PGW group (6 vs. 18 min; P = 0.004; respectively). In the PGW group, post-ERCP pancreatitis (PEP) occurred in 3 of 22 cases (13.6%). No adverse events, including PEP, occurred in the uneven group.

Conclusions: The uneven method may be a useful option of selective biliary cannulation in BE-ERCP for the patients with surgically altered gastrointestinal anatomy.
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http://dx.doi.org/10.1007/s00464-019-07228-5DOI Listing
March 2020

Utility of EUS elastography in the diagnosis of gastric subepithelial tumors: a pilot study (with video).

Gastrointest Endosc 2020 01 17;91(1):172-177.e2. Epub 2019 Sep 17.

Department of Gastroenterology, Cha Bundang Medical Center, Cha University College of Medicine, Seongnam-si, Korea.

Background And Aims: EUS elastography is a real-time imaging technique that analyzes tissue elasticity. The aim of this study was to investigate the applicability of quantitative EUS elastography in the differential diagnosis of gastric subepithelial tumors (SETs).

Methods: We prospectively registered 41 consecutive patients with gastric SETs and measured their strain ratios with EUS elastography. The strain ratios of gastric SETs were compared with the histopathologic diagnosis.

Results: Thirty-one patients (mean age, 51.4 ± 12.6 years) were included in the analysis. The mean size of the SETs was 2.3 ± 0.7 cm. Lipomas had the lowest strain ratio of 1.6 (1.1-2.0), followed by leiomyomas 6.0 (2.0-29.0), ectopic pancreas 11.8 (1.7-29.3), gastrointestinal stromal tumors (GISTs) 51.1 (29.0-67.0), and schwannomas 62.0. With a cut-off value of 22.7, EUS elastography could differentiate GISTs from leiomyomas with sensitivity and specificity of 100% and 94.1%, respectively (P = .001; 95% confidence interval, 0.979-1.000).

Conclusions: EUS elastography could be a promising diagnostic adjunct for the assessment of gastric SETs, especially in differentiating GISTs from leiomyomas.
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http://dx.doi.org/10.1016/j.gie.2019.09.012DOI Listing
January 2020

[Relief of Obstruction in the Management of Pancreatic Cancer].

Authors:
Chang-Il Kwon

Korean J Gastroenterol 2019 Aug;74(2):69-80

Digestive Disease Center, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Korea.

Pancreatic cancer is a major cause of cancer-related mortality and morbidity, and its incidence is increasing as the population is aging. On the other hand, significant improvement in the prognosis has not occurred. The absence of early diagnosis means that many patients are diagnosed only when they develop symptoms, such as jaundice, due to a biliary obstruction. The role of endoscopy in multidisciplinary care for patients with pancreatic cancer continues to evolve. Controversy remains regarding the best preoperative biliary drainage in patients with surgically resectable pancreatic head cancer. In general, patients undergoing a surgical resection usually do not require preoperative biliary drainage unless they have cholangitis or receive neoadjuvant chemotherapy. If biliary drainage is performed prior to surgery, the patient's condition and a multidisciplinary approach should be considered. With the increasing life expectancy of patients with pancreatic cancer, the need for more long-time biliary drainage or pre-operative biliary drainage is also increasing. Strong evidence of endoscopic retrograde cholangiopancreatography (ERCP) as a first-line and essential treatment for biliary decompression has been provided. On the other hand, the use of endoscopic ultrasound-guided biliary drainage as well as percutaneous biliary drainage has been also recommended. During ERCP, self-expandable metal stent could be recommended instead of a plastic stent for the purpose of long stent patency and minimizing stent-induced complications. In this review, several points of view regarding the relief of obstruction in patients with pancreatic cancer, and optimal techniques are being discussed.
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http://dx.doi.org/10.4166/kjg.2019.74.2.69DOI Listing
August 2019

Technical Reports of Endoscopic Retrograde Cholangiopancreatography Guidewires on the Basis of Physical Properties.

Clin Endosc 2020 Jan 6;53(1):65-72. Epub 2019 Aug 6.

Research Group for Endoscopic Instruments and Stents, Korean Society of Gastrointestinal Endoscopy, Seoul, Korea.

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 six-stranded 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).

Conclusion: 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.
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http://dx.doi.org/10.5946/ce.2019.114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7003007PMC
January 2020

Endoscopic Submucosal Dissection Followed by Concurrent Chemoradiotherapy in Patients with Early Esophageal Cancer with a High Risk of Lymph Node Metastasis.

Clin Endosc 2019 Sep 14;52(5):502-505. Epub 2019 May 14.

Digestive Disease Center, CHA Bundang Medical Center, CHA University, Seongnam, Korea.

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.
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http://dx.doi.org/10.5946/ce.2018.176DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6785410PMC
September 2019

Recent advances in the diagnosis and management of chronic pancreatitis.

Korean J Intern Med 2019 Mar 25;34(2):242-260. Epub 2019 Feb 25.

Division of Gastroenterology/Hepatology, Indiana University School of Medicine, Indianapolis, IN, USA.

Chronic pancreatitis is a chronic condition characterized by pancreatic inflammation that causes fibrosis and the destruction of exocrine and endocrine tissues. Chronic pancreatitis is a progressive disease, and no physiological treatment is available to reverse its course. However, with advances in medical technology, the existing diagnostic and treatment methods for chronic pancreatitis are evolving. Managing patients with chronic pancreatitis is challenging and necessitates a multidisciplinary approach. In this review, we discuss the recent advances in the diagnosis and management of chronic pancreatitis and introduce future alternative modalities.
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http://dx.doi.org/10.3904/kjim.2019.051DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6406102PMC
March 2019

Robotic transduodenal ampullectomy: A novel minimally invasive approach for ampullary neoplasms.

Int J Med Robot 2019 Jun 8;15(3):e1979. Epub 2019 Jan 8.

Gastroenterology, CHA Bundang Medical Center, CHA University, Seongnam, South Korea.

Background: The adoption of minimally invasive surgery for transduodenal ampullectomy has been slow because of special characteristics and complexity of this procedure.

Methods: Six patients underwent robotic transduodenal ampullectomy. We employed novel methods to facilitate exposure of the ampulla.

Results: All patients completed robotic transduodenal ampullectomy, but one patient was immediately converted to robotic pancreaticoduodenectomy because of presence of invasive carcinoma on frozen biopsy. The final pathologic report revealed high-grade dysplasia in four patients, low-grade dyplasia in one, and T2N0 in one patient who converted to pancreaticoduodenectomy. There was no immediate postoperative complication or mortality. One patient was readmitted after 3 months because of stricture of the bile duct outlet. There was no recurrence over a median follow-up period of 20 months.

Conclusion: An appropriate combination of patient positioning and retraction method helps the robot surgical system to provide competent performance for sophisticated and precise manipulation of ampullary lesions.
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http://dx.doi.org/10.1002/rcs.1979DOI Listing
June 2019

Will New Instruments for Endoscopic Ultrasound-Guided Tissue Acquisition Make Us Happy?

Authors:
Chang-Il Kwon

Clin Endosc 2018 Nov 23;51(6):510-512. Epub 2018 Nov 23.

Digestive Disease Center, CHA Bundang Medical Center, CHA University, Seongnam, Korea.

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http://dx.doi.org/10.5946/ce.2018.164DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6283755PMC
November 2018

Evaluation of valve function in antireflux biliary metal stents.

BMC Gastroenterol 2018 Oct 19;18(1):150. Epub 2018 Oct 19.

Department of Internal Medicine, Pusan National University School of Medicine and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea.

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.
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http://dx.doi.org/10.1186/s12876-018-0878-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6194677PMC
October 2018

An Unusual Mimicker of a Pancreatic Pseudocyst.

Clin Endosc 2018 May 22;51(3):304-305. Epub 2018 Mar 22.

Digestive Disease Center, CHA Bundang Medical Center, CHA University, Seongnam, Korea.

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http://dx.doi.org/10.5946/ce.2017.160DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5997071PMC
May 2018

Additional flap on plastic stents for improved antimigration effect in the treatment of post-cholecystectomy bile leak.

Endosc Int Open 2018 04 29;6(4):E489-E494. Epub 2018 Mar 29.

Division of Gastroenterology/Hepatology, Indiana University School of Medicine, Indianapolis, Indiana, United States.

Background And Study Aims: In plastic stent insertion for treatment of post-cholecystectomy bile leak, stent migration may be more common due to the absence of a shelf to anchor the stent. We evaluated how adding a flap to straight plastic stents for this indication might influence the rate of stent migration when compared to use of conventional plastic stents.

Patients And Methods: This is a retrospective study including patients referred for ERCP for treatment of post-cholecystectomy bile leak. Patients with a customized anti-migration flap stent had the additional flap created on the distal end of straight plastic stents, intended to aid in anchoring in the distal supra-sphincteric biliary duct. The primary endpoint is stent migration events. The secondary endpoint is bile leak resolution after first ERCP session.

Results: Thirty-two patients were treated with the experimental additional flap stents and 225 patients were treated with standard straight biliary stents. The total failure rate of bile leak resolution after a single endoscopic treatment for all treated was 10.5 % (27/257) and the total stent migration rate for all enrolled was 15.2 % (39/257). Stent migration rate was lower in the additional flap stent group than in the conventional group (3.1 % vs. 16.9 %, respectively,  = 0.04). Furthermore, significantly more patients had resolution of their bile leak after the first ERCP session in the group with the additional flap (100 % vs. 88 %, respectively,  = 0.03).

Conclusion: A plastic biliary stent with an extra flap may have improved performance with regard to stent migration and resolution of bile leak over standard plastic biliary stents.
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http://dx.doi.org/10.1055/s-0043-125361DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5876032PMC
April 2018

Performance of disposable endoscopic forceps according to the manufacturing techniques.

Korean J Intern Med 2019 May 5;34(3):530-538. Epub 2018 Mar 5.

Digestive Disease Center, CHA Bundang Medical Center, CHA University, Seongnam, Korea.

Background/aims: Recently, to lower the production costs and risk of infection, new disposable biopsy forceps made using simple manufacturing techniques have been introduced. However, the effects of the manufacturing techniques are unclear. The aim of this study was to evaluate which types of biopsy forceps could obtain good-quality specimens according to the manufacturing techniques.

Methods: By using an in vitro nitrile glove popping model, we compared the popping ability among eight different disposable biopsy forceps (one pair of biopsy forceps with cups made by a cutting method [cutting forceps], four pairs of biopsy forceps with cups made by a pressing method [pressing forceps], and three pairs of biopsy forceps with cups made using a injection molding method [molding forceps]). Using an in vivo swine model, we compared the penetration depth and quality of specimen among the biopsy forceps.

Results: In the in vitro model, the molding forceps provided a significantly higher popping rate than the other forceps (cutting forceps, 25.0%; pressing forceps, 17.5%; and molding forceps, 41.7%; p = 0.006). In the in vivo model, the cutting and pressing forceps did not provide larger specimens, deeper biopsy specimen, and higher specimen adequacy than those obtained using the molding forceps (p = 0.2631, p = 0.5875, and p = 0.2147, respectively). However, the molding forceps showed significantly more common crush artifact than the others (cutting forceps, 0%; pressing forceps, 5.0%; and molding forceps, 43.3%; p = 0.0007).

Conclusion: The molding forceps provided lower performance than the cutting and pressing forceps in terms of crush artifact.
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http://dx.doi.org/10.3904/kjim.2017.191DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6506737PMC
May 2019

Low Serum Pancreatic Amylase and Lipase Values Are Simple and Useful Predictors to Diagnose Chronic Pancreatitis.

Gut Liver 2017 11;11(6):878-883

Division of Gastroenterology and Hepatology, Indiana University School of Medicine, Indianapolis, IN, USA.

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.
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http://dx.doi.org/10.5009/gnl17066DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5669605PMC
November 2017

Immediate Endoscopic Management of an Intramural Hematoma Developed during Colonoscopy.

Clin Endosc 2017 Sep 3;50(5):508-509. Epub 2017 Aug 3.

Digestive Disease Center, CHA Bundang Medical Center, CHA University, Seongnam, Korea.

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http://dx.doi.org/10.5946/ce.2017.037DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5642068PMC
September 2017

Experimental study on the friction effect of plastic stents for biliary stone fragmentation (with video).

Dig Endosc 2018 Jan 20;30(1):107-113. Epub 2017 Jul 20.

Digestive Disease Center, CHA Bundang Medical Center, CHA University, Seongnam, Korea.

Background And Aim: In patients with irretrievable or intractable bile duct stone, temporary insertion of a plastic stent (PS) followed by further endoscopic retrograde cholangiopancreatography (ERCP) or surgery has been recommended as a 'bridge' therapy. However, the exact mechanism of stone fragmentation has not been discovered. The aim of the present study was to evaluate whether PS shape can facilitate stone fragmentation.

Methods: Using a new in vitro bile flow phantom model, we compared the friction effect among three different PS groups (straight PS group, double pigtail-shaped PS group, and screw-shaped PS group) and a control group. Each group had 10 silicon tube blocks that separately contained one stone and two PS. The control group had 10 blocks each with only a stone and no PS. We carried out analysis of the friction effect by stone weight and volume changes among the groups, excluding fragmented stones.

Results: After 8 weeks, complete fragmentation was noted in one out of 34 cholesterol stones (2.9%) and in four out of six pigmented stones (66.7%). Fragmentation tended to be more prominent in the screw-shaped PS group than in the straight PS group, double pigtail-shaped group, and control group (volume change: -11.33%, 7.94%, 4.43%, and 2.05%, respectively, P = 0.1390; weight change: -9.30%, 0.71%, -0.10%, and -1.23%, respectively, P = 0.3553).

Conclusion: Stone fragmentation may be induced by PS friction effect. Also, screw-shaped plastic stents may improve friction effect. These results may help guide future PS development and clinical decisions.
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http://dx.doi.org/10.1111/den.12906DOI Listing
January 2018

Synthetic 8-hydroxydeoxyguanosine inhibited metastasis of pancreatic cancer through concerted inhibitions of ERM and Rho-GTPase.

Free Radic Biol Med 2017 09 8;110:151-161. Epub 2017 Jun 8.

CHA Cancer Prevention Research Center, CHA Bio Complex, Seongnam 13488, Republic of Korea; CHA University Bundang Medical Center, Digestive Disease Center, Seongnam 13496, Republic of Korea. Electronic address:

8-hydroxydeoxyguanosine (8-OHdG) is generated consequent to oxidative stress, but its paradoxical anti-oxidative, anti-inflammatory, and anti-mutagenic effects via Rho-GTPase inhibition were noted in various models of inflammation and cancer. Metastasis occurs through cell detachment, epithelial-mesenchymal transition (EMT), and cell migration; during these processes, changes in cell morphology are initiated through Rho-GTPase-dependent actin cytoskeleton polymerization. In this study, we explored the anti-metastatic mechanisms of 8-OHdG in Panc-1 pancreatic cancer cells. 8-OHdG inhibits cell migration by inactivating ERM and Rho-GTPase proteins, and inhibiting focal adhesion kinase (FAK) and matrix metalloproteinases (MMPs). At 15min, 8-OHdG significantly inactivated ERM (p < 0.05) and led to a significant retardation of wound healing; siERM and H1152 (ROCK inhibitor) had similar effects (p < 0.05). However, FAK inhibitor 14, DPI (NOX inhibitor), and NAC (antioxidant) significantly delayed wound healing without inhibiting ERM or CD44 (p < 0.05). In the experiments on cell migration, siERM, siCD44, DPI, and 8-OHdG significantly inhibited MMPs. 8-OHdG significantly decreased DCF-DA activation in Panc-1 pancreatic cancer cells and down-regulated NOXs (nox-1, nox-2, and nox-3). Finally, all of these anti-migration actions of 8-OHdG resulted in significant inhibition of EMT, as evidenced by the up-regulation of ZO-1 and claudin-1 and down-regulation of vimentin. We found significant inhibition of lung metastasis of Panc-1 cells by 8-OHdG. In conclusion, exogenous 8-OHdG had potent anti-metastasis effects mediated by either ERM or Rho GTPase inhibition in metastasis-prone pancreatic cancer cells.
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http://dx.doi.org/10.1016/j.freeradbiomed.2017.06.003DOI Listing
September 2017

The Stent Patency and Migration Rate of Different Shaped Plastic Stents in Bile Flow Phantom Model and In Vivo Animal Bile Duct Dilation Model.

Dig Dis Sci 2017 05 9;62(5):1246-1255. Epub 2017 Mar 9.

Digestive Disease Center, CHA Bundang Medical Center, CHA University, Seongnam, Republic of Korea.

Background/aim: In research and development of biliary plastic stents (PS), continuous efforts have been made to overcome short patency time and high rate of migration. The aim of this study was to evaluate the patency and migration rate of different PS shapes for a given period of time.

Methods: Using an in vitro bile phantom model, we compared the patency among different shapes of PS (three straight PS, four double-pigtail PS, and a new screw-shaped PS). We performed an analysis of the degree of luminal narrowing by light microscopic examination. Using an in vivo swine model, we compared the patency and migration rate among the three different types of PS.

Results: Eight weeks after the bile exposure in the bile flow phantom model, 80 PS were retrieved and analyzed. The straight PS showed less biofilm formation and luminal narrowing than other types of PS (p < 0.05). Forty-nine PS were inserted into the dilated bile ducts of 10 swine models, and 39 PS were successfully retrieved 8 weeks later. The stent migration occurred less frequently in the double-pigtail PS and the screw-shaped PS than it did in the straight PS (11.1, 10, and 27.3%, respectively). However, there was no statistical difference in stent patency among the different shapes.

Conclusions: Stent patency may not be significantly different depending on the shape of PS for 8 weeks. The screw-shaped PS showed similar patency and migration rate to the double-pigtail PS. These results may help guiding future PS development and clinical decisions.
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http://dx.doi.org/10.1007/s10620-017-4514-1DOI Listing
May 2017
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