Woo Jin Chung

Keimyung University, Sŏul, Seoul, South Korea

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Publications (78)191.24 Total impact

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    ABSTRACT: The aim of this study was to compare the efficacy of hepatic arterial infusion chemotherapy (HAIC) and sorafenib in advanced hepatocellular carcinoma (HCC) patients with portal vein tumor thrombosis (PVTT).
    Journal of gastroenterology. 07/2014;
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    ABSTRACT: To compare outcomes using the novel portable endoscopy with that of nasogastric (NG) aspiration in patients with gastrointestinal bleeding.
    World journal of gastroenterology : WJG. 07/2014; 20(25):8221-8.
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    ABSTRACT: To compare the esophagogastric junction (EGJ) areas observed in sedated and non-sedated patients during esophagogastroduodenoscopy (EGD). Data were collected prospectively from consecutive patients who underwent EGD for various reasons. The patients were divided into three groups according to the sedation used: propofol, midazolam, and control (no sedation). The EGJ was observed during both insertion and withdrawal of the endoscope. The extent of the EGJ territory observed was classified as excellent, good, fair, or poor. In addition, the time the EGJ was observed was estimated. The study included 103 patients (50 males; mean age 58.44 ± 10.3 years). An excellent observation was achieved less often in the propofol and midazolam groups than in the controls (27.3%, 28.6% and 91.4%, respectively, P < 0.001). There was a significant difference in the time at which EGJ was observed among the groups (propofol 20.7 ± 11.7 s vs midazolam 16.3 ± 7.3 s vs control 11.6 ± 5.8 s, P < 0.001). Multivariate analysis showed that sedation use was the only independent risk factor for impaired EGJ evaluation (propofol, OR = 24.4, P < 0.001; midazolam, OR = 25.3, P < 0.001). Hiccoughing was more frequent in the midazolam group (propofol 9% vs midazolam 25.7% vs control 0%, P = 0.002), while hypoxia (SaO2 < 90%) tended to occur more often in the propofol group (propofol 6.1% vs midazolam 0% vs control 0%, P = 0.101). Sedation during EGD has a negative effect on evaluation of the EGJ.
    World Journal of Gastroenterology 05/2014; 20(18):5527-32. · 2.55 Impact Factor
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    ABSTRACT: A novel synthetic and processing strategy for converting elemental sulfur into polymeric and nanocomposite materials is reported. We describe a facile one-pot reaction using elemental sulfur and oleylamine as comonomers to prepare high sulfur content copolymers and lead sulfide nanoparticle (PbS NP) nanocomposites. This process enables the preparation of solution processable copolymers and nanocomposites, where the loading and dispersion of PbS NP inclusions could be precisely controlled. We demonstrate the dual roles of oleylamine with sulfur for both the copolymerization of sulfur copolymers as well as the in situ synthesis of PbS NPs in a one-pot fashion.
    Polym. Chem. 05/2014; 5(11).
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    ABSTRACT: Polymers for IR imaging: The preparation of high refractive index polymers (n = 1.75 to 1.86) via the inverse vulcanization of elemental sulfur is reported. High quality imaging in the near (1.5 μm) and mid-IR (3-5 μm) regions using high refractive index polymeric lenses from these sulfur materials was demonstrated.
    Advanced Materials 03/2014; · 14.83 Impact Factor
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    ABSTRACT: Hepatocellular carcinoma (HCC) is the fourth most common form of cancer in the Korean population, caused primarily by infection with either the Hepatitis B or C virus. Progression of this disease is frequently associated with mutations in either phosphoinositide-3-kinase, catalytic, alpha (PIK3CA) or hepatitis B virus X (HBx) gene. Previous studies have examined the frequency of PIK3CA mutations in HCC, although the clinical significance of these mutations has not been studied in a Korean population. In addition, HBx appears to play a key role in modulating a wide range of cellular functions, leading to HCC. In this study, we examined microdissected tumor samples from 50 HCC patients who underwent hepatectomy at Keimyung University Dongsan Medical Center. These patients were screened for mutations in PIK3CA and HBx to identify the clinical outcomes associated with these mutations. Exons 9 and 20 of PIK3CA and the entirety of HBx were screened for mutations by polymerase chain reaction and direct DNA sequencing. PIK3CA mutations were detected in 7 of 50 patients (14%). Among the 42 patients who were seropositive for hepatitis B, 17 (40.5%) had HBx mutations and 4 (9.52%) had mutations in PIK3CA. PIK3CA mutations were strongly correlated with tumor size. Patients harboring HBx mutations exhibited a longer time to recurrence; this difference was statistically significant not only in comparison with the PIK3CA mutation but also compared with those without any mutations. This result suggests a role for PIK3CA and HBx mutations as prognostic markers in HCC.
    Apmis 03/2014; · 2.07 Impact Factor
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    ABSTRACT: This retrospective study assessed the clinical outcome of a transjugular intrahepatic portosystemic shunt (TIPS) procedure for managing portal hypertension in Koreans with liver cirrhosis. Between January 2003 and July 2013, 230 patients received a TIPS in 13 university-based hospitals. Of the 229 (99.6%) patients who successfully underwent TIPS placement, 142 received a TIPS for variceal bleeding, 84 for refractory ascites, and 3 for other indications. The follow-up period was 24.9±30.2 months (mean±SD), 74.7% of the stents were covered, and the primary patency rate at the 1-year follow-up was 78.7%. Hemorrhage occurred in 30 (21.1%) patients during follow-up; of these, 28 (93.3%) cases of rebleeding were associated with stent dysfunction. Fifty-four (23.6%) patients developed new hepatic encephalopathy, and most of these patients were successfully managed conservatively. The cumulative survival rates at 1, 6, 12, and 24 months were 87.5%, 75.0%, 66.8%, and 57.5%, respectively. A high Model for End-Stage Liver Disease (MELD) score was significantly associated with the risk of death within the first month after receiving a TIPS (P=0.018). Old age (P<0.001), indication for a TIPS (ascites vs. bleeding, P=0.005), low serum albumin (P<0.001), and high MELD score (P=0.006) were associated with overall mortality. A high MELD score was found to be significantly associated with early and overall mortality rate in TIPS patients. Determining the appropriate indication is warranted to improve survival in these patients.
    Clinical and molecular hepatology. 03/2014; 20(1):18-27.
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    Woo Jin Chung
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    ABSTRACT: A major cause of cirrhosis related morbidity and mortality is the development of variceal bleeding, a direct consequence of portal hypertension. Less common causes of gastrointestinal bleeding are peptic ulcers, malignancy, angiodysplasia, etc. Upper gastrointestinal bleeding has been classified according to the presence of a variceal or non-variceal bleeding. Although non-variceal gastrointestinal bleeding is not common in cirrhotic patients, gastroduodenal ulcers may develop as often as non-cirrhotic patients. Ulcers in cirrhotic patients may be more severe and less frequently associated with chronic intake of non-steroidal anti-inflammatory drugs, and may require more frequently endoscopic treatment. Portal hypertensive gastropathy (PHG) refers to changes in the mucosa of the stomach in patients with portal hypertension. Patients with portal hypertension may experience bleeding from the stomach, and pharmacologic or radiologic interventional procedure may be useful in preventing re-bleeding from PHG. Gastric antral vascular ectasia (GAVE) seems to be different disease entity from PHG, and endoscopic ablation can be the first-line treatment.
    Clinical and molecular hepatology. 03/2014; 20(1):1-5.
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    ABSTRACT: Sulfur-rich copolymers based on poly(sulfur-random-1,3-diisopropenylbenzene) (poly(S-r-DIB)) were synthesized via inverse vulcanization to create cathode materials for lithium–sulfur battery applications. These materials exhibit enhanced capacity retention (1005 mAh/g at 100 cycles) and battery lifetimes over 500 cycles at a C/10 rate. These poly(S-r-DIB) copolymers represent a new class of polymeric electrode materials that exhibit one of the highest charge capacities reported, particularly after extended charge–discharge cycling in Li–S batteries.
    ACS Macro Letters. 02/2014; 3(3):229–232.
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    ABSTRACT: G protein‐coupled receptor (GPCR) cell signalling cascades are initiated upon binding of a specific agonist ligand to its cell surface receptor. Linking multiple heterologous ligands that simultaneously bind and potentially link different receptors on the cell surface is a unique approach to modulate cell responses. Moreover, if the target receptors are selected based on analysis of cell‐specific expression of a receptor combination, then the linked binding elements might provide enhanced specificity of targeting the cell type of interest, that is, only to cells that express the complementary receptors. Two receptors whose expression is relatively specific (in combination) to insulin‐secreting pancreatic β‐cells are the sulfonylurea‐1 (SUR1) and the glucagon‐like peptide‐1 (GLP‐1) receptors. A heterobivalent ligand was assembled from the active fragment of GLP‐1 (7–36 GLP‐1) and glibenclamide, a small organic ligand for SUR1. The synthetic construct was labelled with Cy5 or europium chelated in DTPA to evaluate binding to β‐cells, by using fluorescence microscopy or time‐resolved saturation and competition binding assays, respectively. Once the ligand binds to β‐cells, it is rapidly capped and presumably removed from the cell surface by endocytosis. The bivalent ligand had an affinity approximately fivefold higher than monomeric europium‐labelled GLP‐1, likely a result of cooperative binding to the complementary receptors on the βTC3 cells. The high‐affinity binding was lost in the presence of either unlabelled monomer, thus demonstrating that interaction with both receptors is required for the enhanced binding at low concentrations. Importantly, bivalent enhancement was accomplished in a cell system with physiological levels of expression of the complementary receptors, thus indicating that this approach might be applicable for β‐cell targeting in vivo.
    ChemBioChem 01/2014; 15(1). · 3.74 Impact Factor
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    ABSTRACT: The results of studies that evaluated predictive factors for rebleeding in non-variceal upper gastrointestinal bleeding are inconsistent. The aim of this study was to investigate predictive factors for 30-day rebleeding in these patients. A consecutive 312 patients presenting symptoms and signs of gastrointestinal bleeding were enrolled in this prospective, observational study. Clinical and demographic characteristics and endoscopic findings were evaluated for potential factors associated with 30-day rebleeding using logistic regression analysis. Overall, 176 patients were included (male, 80.1%; mean age, 59.7±16.0 yr). Rebleeding within 7 and 30 days occurred in 21 (11.9%) and 27 (15.3%) patients, respectively. We found that chronic kidney disease (CKD) (OR, 10.29; 95% CI, 2.84-37.33; P<0.001), tachycardia (pulse>100 beats/min) during the admission (OR, 3.79; 95% CI, 1.25-11.49; P=0.019), and Forrest classes I, IIa, and IIb (OR, 6.14; 95% CI, 1.36-27.66; P=0.018) were significant independent predictive factors for 30-day rebleeding. However, neither Rockall nor Blatchford scores showed statistically significant relationships with 30-day rebleeding in a multivariate analysis. CKD, hemodynamic instability during hospitalization, and an endoscopic high-risk appearance are significantly independent predictors of 30-day rebleeding in patients with non-variceal upper gastrointestinal bleeding. These factors may be useful for clinical management of such patients.
    Journal of Korean medical science 10/2013; 28(10):1500-6. · 0.84 Impact Factor
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    ABSTRACT: The synthesis and thermomechanical properties of a novel class of self-healing perfluoropolyethers (PFPEs) is reported. By decoration of 2-ureido-4[1H]-pyrimidone end groups on the termini of low molar mass PFPE, the formation of supramolecular polymers and networks held together via hydrogen bonding associations was achieved. These novel supramolecular polymer materials exhibit a combination of enhanced modulus and elasticity, along with self-healing properties, where rapid self-healing time was demonstrated using dynamic rheological measurements. These types of supramolecular PFPEs are anticipated to be useful for a number of emerging areas in lubrication. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3598–3606
    Journal of Polymer Science Part A Polymer Chemistry 09/2013; 51(17):3598-3606. · 3.54 Impact Factor
  • Woo Jin Chung
    The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi 07/2013; 62(1):78-81.
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    ABSTRACT: The environmental factors human rhinoviruses (HRVs) and house dust mites (HDMs) are the most common causes of acute exacerbations of asthma. The aim of this study was to compare the chemokine production induced by HRVs in airway epithelial cells with that induced by other respiratory viruses, and to investigate synergistic interactions between HRVs and HDMs on the induction of inflammatory chemokines in vitro. A549 human airway epithelial cells were infected with either rhinovirus serotype 7, respiratory syncytial virus (RSV)-A2 strain, or adenovirus serotype 3 and analyzed for interleukin (IL)-8 and regulated on activation, normal T-cell expressed and secreted (RANTES) release and mRNA expression. Additionally, activation of nuclear factor (NF)-κB and activator protein (AP)-1 were evaluated. The release of IL-8 and RANTES was also measured in cells stimulated simultaneously with a virus and the HDM allergen, Der f1. HRV caused greater IL-8 and RANTES release and mRNA expression compared with either RSV or adenovirus. NF-κB and AP-1 were activated in these processes. Cells incubated with a virus and Der f1 showed an increased IL-8 release. However, compared with cells incubated with virus alone as the stimulator, only HRV with Der f1 showed a statistically significant increase. IL-8 and RANTES were induced to a greater extent by HRV compared with other viruses, and only HRV with Der f1 acted synergistically to induce bronchial epithelial IL-8 release. These findings may correspond with the fact that rhinoviruses are identified more frequently than other viruses in cases of acute exacerbation of asthma.
    Allergy, asthma & immunology research 07/2013; 5(4):216-23. · 2.65 Impact Factor
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    ABSTRACT: The synthesis of single chain nanoparticles has been achieved by the synthesis of a linear polystyrenic precursor carrying 3,4-propylenedioxythiophene groups via atom transfer radical polymerization followed by intramolecular crosslinking via oxidative polymerization. This methodology enabled the introduction of electroactive inclusions into single chain polymer nanoparticles, while concurrently promoting intramolecular collapse.
    Polym. Chem. 06/2013; 4(13):3765-3773.
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    ABSTRACT: An excess of elemental sulfur is generated annually from hydrodesulfurization in petroleum refining processes; however, it has a limited number of uses, of which one example is the production of sulfuric acid. Despite this excess, the development of synthetic and processing methods to convert elemental sulfur into useful chemical substances has not been investigated widely. Here we report a facile method (termed 'inverse vulcanization') to prepare chemically stable and processable polymeric materials through the direct copolymerization of elemental sulfur with vinylic monomers. This methodology enabled the modification of sulfur into processable copolymer forms with tunable thermomechanical properties, which leads to well-defined sulfur-rich micropatterned films created by imprint lithography. We also demonstrate that these copolymers exhibit comparable electrochemical properties to elemental sulfur and could serve as the active material in Li-S batteries, exhibiting high specific capacity (823 mA h g(-1) at 100 cycles) and enhanced capacity retention.
    Nature Chemistry 06/2013; 5(6):518-24. · 21.76 Impact Factor
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    ABSTRACT: The synthesis of poly(octadecyl methacrylate) brushes on planar Si substrates using surface-initiated atom transfer radical polymerization (SI-ATRP) is reported. SI-ATRP of octadecyl methacrylate from a silane initiator-modified Si substrate yielded well-defined homopolymer brushes of varying molar mass (5000–38 000 g mol−1) and film thickness from around 2 to 20 nm. Correlation of both free polymer molar mass and brush thicknesses confirmed controlled surface-initiated ATRP from these modified surfaces. By optimization of brush molar mass, film thickness and thin-film processing, we observed side chain crystallization of tethered poly(octadecyl methacrylate) chains, resulting in the formation of lamellar morphologies with high-aspect-ratio nanofibers. Copyright © 2013 John Wiley & Sons, Ltd.
    Applied Organometallic Chemistry 05/2013; 27(11):378. · 2.01 Impact Factor
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    ABSTRACT: BACKGROUND: The use of self-expandable metal stents (SEMS) for the treatment of malignant colorectal obstruction is increasing. However, results of risk factors for its complications are inconsistent. This study aimed to examine the clinical effectiveness of the procedure as well as the complications and risk factors associated with the complications. METHODS: Medical records of patients with malignant colorectal obstruction who underwent endoscopic placement of covered or uncovered SEMS were reviewed retrospectively. The procedure was performed by two endoscopists with experience in pancreatobiliary endoscopy. RESULTS: A total of 152 patients were included (102 men; mean age, 70 ± 12.5 years). The procedure was performed for palliative management in 83 patients and performed as a bridge to surgery in 69 patients. There were 111 uncovered stents and 41 covered stents. The technical success rate was 100 % and the clinical success rate 94.1 %. Overall complications were observed in 49 patients (32.2 %) during the follow-up period (median, 98 days; interquartile range, 19-302 days). Obstruction (17.1 %), migration (7.9 %), perforation (5.2 %), bleeding (1.3 %), and tenesmus (0.7 %) were the causes of the complications. Stage IV disease, carcinomatosis peritonei, complete obstruction of the colon, palliative intention, and covered stents increased the complications based on the univariate analysis. Multivariate analysis revealed that complete obstruction of the colon and covered stents were significantly independent risk factors for complications. In the palliative group, Kaplan-Meier analysis showed significantly shorter median duration to the onset of complications in the covered stent group than in the uncovered stent group. CONCLUSIONS: Although SEMS in patients with malignant colorectal obstruction is effective both as palliative therapy and as a bridge to surgery, one-third of patients experienced complications. Severity of obstruction and stent type can influence outcomes.
    Surgical Endoscopy 03/2013; · 3.43 Impact Factor
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    ABSTRACT: Utilization of the active cathode material in high-energy density Li-S batteries limited by the insulating nature of sulfur and losses in the form of insoluble polysulfides was improved by the use of 1,3-diisopropenylbenzene (DIB) copolymerized with molten sulfur. This approach termed, inverse vulcanization, transforms elemental sulfur into chemically stable processable copolymer forms with tunable thermomechanical properties. According to dielectric spectroscopy and dc conductivity measurements, composite sulfur-DIB copolymer cathodes exhibit a glassy-state beta relaxation related to short sulfur segments or to the DIB cross-linker. High-resolution AEM and FESEM studies down to the atomic scale reveal multiscale 3D-architectures created within the pristine and cycled composite cathodes with various contents of the electroactive copolymers. The morphology, structures, bonding and local compositional distributions of the constituents (sulfur, copolymers, aggregated conductive carbon nanoparticles) as well as extended pore structures and their transformations under cycling have been examined to provide insights into mechanisms of the enhanced capacity retention in the modified Li-S cells.
    03/2013;
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    ABSTRACT: BACKGROUND: There have been substantial differences in pathologic results between forceps biopsies (FB) and resection specimen (RS) of the colorectal neoplasm. The aim of this study was to investigate predictive factors of the underestimated pathology in FB compared with RS. METHODS: Data from 248 consecutive patients with colorectal intraepithelial neoplasm ≥10 mm, which was removed by endoscopic mucosal resection or endoscopic submucosal dissection, were reviewed retrospectively. We excluded patients with no FB on the neoplasm before the resection. Demographic data and tumor characteristics including size, locations, surface appearances, and the number of FB fragments were evaluated as potential factors associated with the discrepancies by logistic regression analysis. RESULTS: Overall, 179 lesions from 171 patients were included in the study (size, 28.37 ± 12.00 mm; range 10-80 mm). The overall number of discrepancy cases was 103 (57.5 %), where 90 (50.3 %) were underestimated in FB and 13 (7.2 %) downgraded in their RS. In the multivariate analysis, round [odds ratio (OR) 4.46, 95 % confidence interval (CI) 1.76-11.30, p = 0.002], depressed (OR 3.23, 95 % CI 1.11-9.39, p = 0.031), and mixed type of surface appearance (OR 5.47, 95 % CI 2.38-12.60, p < 0.001), and tumor size ≥30 mm (OR 2.14, 95 % CI 1.12-4.10, p = 0.021) were significant predictive factors for underestimated pathology in FB. CONCLUSIONS: Underestimation in FB is remarkable in colorectal tumors ≥10 mm in size. This discrepancy is associated with the tumor characteristics, such as surface appearance and size. Endoscopic characteristics of tumor should be carefully examined for an adequate management strategy of colorectal epithelial neoplasm.
    Surgical Endoscopy 02/2013; · 3.43 Impact Factor

Publication Stats

293 Citations
191.24 Total Impact Points

Institutions

  • 2005–2014
    • Keimyung University
      • Dongsan Medical Center
      Sŏul, Seoul, South Korea
    • Yonsei University Hospital
      Sŏul, Seoul, South Korea
  • 2009–2013
    • The University of Arizona
      • Department of Chemistry and Biochemistry (College of Science)
      Tucson, Arizona, United States
  • 2010
    • Massachusetts General Hospital
      • Department of Medicine
      Boston, MA, United States
    • Harvard Medical School
      • Department of Medicine
      Boston, Massachusetts, United States
  • 2006
    • Kyung Hee University
      • College of Medicine
      Seoul, Seoul, South Korea
  • 2003
    • Yonsei University
      Sŏul, Seoul, South Korea