113 results on '"Jeong KW"'
Search Results
2. The Mediating Effects of Anxiety and Happiness and the Moderating Effect of Social Network Services for Employee Silence and Psychological Withdrawal Behavior
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Xue Tong Dong, Yang Woon Chung, and Jeong Kwon Yun
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History of scholarship and learning. The humanities ,AZ20-999 ,Social Sciences - Abstract
Employees not being able to express their thoughts and opinions about work has been argued to result in detrimental organizational outcomes. Employee silence has recently become a prevalent organizational issue but studies that have explored proximal and distal outcomes of silence are scarce. Therefore, the study explored anxiety and happiness as mediating mechanisms for the relationship between silence and psychological withdrawal and the moderating effect of social network services usage for the relationship between silence and the mediators. The study conducted a two-wave self-reported questionnaire and sampled 257 full-time employees. Anxiety and happiness were found to mediate the relationship and social network services moderated the relationships between silence with the mediators. Moreover, supplementary analysis found mediated moderation for the study.
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- 2023
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3. Novel non-plasmonic nanolasers empowered by topology and interference effects
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Hwang Min-Soo, Kim Ha-Reem, Jeong Kwang-Yong, Park Hong-Gyu, and Kivshar Yuri
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bound states in the continuum ,mie resonances ,nanolaser ,spaser ,topological photonics ,Physics ,QC1-999 - Abstract
Historically, nanophotonics deals with a control of light at the nanoscale being closely connected with the rapid advances in plasmonics – the physics of surface plasmon polaritons supported by metal–dielectric interfaces. Properly engineered nanostructures allow the subwavelength propagation of light and its strong confinement in nanowaveguides and nanocavities, making possible the field enhancement and lasing. Spaser was suggested as a special type of nanolaser with a very small footprint that can be modulated quickly thus becoming a good candidate for on-chip optical data processing. However, recent developments in the physics of high-index dielectric nanoparticles and resonant dielectric metasurfaces allowed to advance the field of nanophotonics and introduce novel nonplasmonic nanostructures and nanolasers empowered by topology and interference effects. Here we present first some examples of experimentally realized spasers, and then discuss the recent developments in the cutting-edge high-index dielectric nanostructures employed for nonplasmonic nanolasers based on Mie resonances, anapole states, bound states in the continuum, and the physics of topological phases.
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- 2021
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4. Unassisted photoelectrochemical water splitting exceeding 7% solar-to-hydrogen conversion efficiency using photon recycling
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Xinjian Shi, Hokyeong Jeong, Seung Jae Oh, Ming Ma, Kan Zhang, Jeong Kwon, In Taek Choi, Il Yong Choi, Hwan Kyu Kim, Jong Kyu Kim, and Jong Hyeok Park
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Science - Abstract
Unassisted water splitting by tandem photoelectrochemical and photovoltaic devices requires optimization of the absorbance and transmittance properties of the front photoelectrode. Here, Shi et al. use a conductive distributed Brag reflector to harvest photons of different wavelengths in the two subcells.
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- 2016
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5. Numerical simulations of two-dimensional floating breakwaters in regular waves using fixed cartesian grid
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Jeong Kwang-Leol and Lee Young-Gill
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Floating breakwater ,Cartesian grid ,Marker-density method ,Lock-in ,Free roll decay ,Ocean engineering ,TC1501-1800 ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 - Abstract
The wave attenuation by floating breakwaters in high amplitude waves, which can lead to wave overtopping and breaking, is examined by numerical simulations. The governing equations, the Navier-Stokes equations and the continuity equation, are calculated in a fixed Cartesian grid system. The body boundaries are defined by the line segment connecting the points where the grid line and body surface meet. No-slip and divergence free conditions are satisfied at the body boundary cell. The nonlinear waves near the moving body is defined using the modified markerdensity method. To verify the present numerical method, vortex induced vibration on an elastically mounted cylinder and free roll decay are numerically simulated and the results are compared with those reported in the literature. Using the present numerical method, the wave attenuations by three kinds of floating breakwaters are simulated numerically in a regular wave to compare the performance.
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- 2014
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6. Effect of removal of free-floating macrophytes on zooplankton habitat in shallow wetland
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Choi Jong-Yun, Jeong Kwang-Seuk, La Geung-Hwan, and Joo Gea-Jae
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submerged macrophyte ,macrophyte habitat ,zooplankton ,species diversity ,shallow wetland ,Aquaculture. Fisheries. Angling ,SH1-691 - Abstract
Submerged macrophytes improve the structural heterogeneity of microhabitats in aquatic ecosystems, often providing an important habitat for zooplankton. However, excessive development of free-floating macrophytes on the water surface can reduce the biomass of submerged macrophytes and result in a relatively simple habitat structure. We hypothesized that controlling the development of free-floating macrophytes would result in a more complex habitat structure by promoting the development of submerged macrophytes. After applying three experimental treatments (NR, no removal; IR, intermediate removal; CR, complete removal of free-floating macrophytes), we found that CR of free-floating macrophytes improved the growth and development of submerged macrophytes and supported a large zooplankton assemblage. However, the largest zooplankton assemblage (in terms of abundance and diversity) was recorded after the IR treatment. Although submerged macrophytes were abundant in the CR treatment, the number, abundance, and density of zooplankton species were much lower than those in the IR treatment. Preferential selection of different macrophyte types by zooplankton presumably led to variation in plant utilization of niches, and the simultaneous presence of different macrophyte life forms created a complex microhabitat structure that induced high species diversity and zooplankton density.
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- 2014
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7. Biodistribution and elimination kinetics of systemic Stx2 by the Stx2A and Stx2B subunit-specific human monoclonal antibodies in mice
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Sheoran Abhineet, Jeong Kwang-il, Mukherjee Jean, Wiffin Anthony, Singh Pradeep, and Tzipori Saul
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Shiga toxin ,Radiolabel ,Antibody ,Toxin elimination ,Toxin concentration ,Pharmacokinetic ,Human monoclonal antibody ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Abstract Background Hemolytic uremic syndrome (HUS) leading to acute kidney failure, is a condition linked to the production of primarily Shiga toxin 2 (Stx2) by some E. coli serotypes. We have previously shown that Stx2 A subunit-specific human monoclonal antibody (HuMAb) 5C12, and B subunit-specific HuMAb 5H8 inhibit cultured cell death, and protect mice and piglets from fatal Stx2-intoxication. We have also shown that 5H8 blocks binding of Stx2 to its cell-surface receptor globotriaosyl ceramide (Gb3), whereas Stx2 when complexed with 5C12 binds Gb3 with higher affinity than Stx2. The mechanism by which 5C12 neutralizes Stx2 in vitro involves trapping of Stx2 in the recycling endosomes and releasing it into the extracellular environment. Because of the clinical implications associated with the formation of Stx2/antibody complexes and the potential for trapping and clearance through a severely damaged kidney associated with HUS, we investigated the likely site(s) of Stx2/antibody localization and clearance in intoxicated mice treated with antibody or placebo. Results Mice were injected with radiolabeled Stx2 (125I-Stx2) 4 hours after administration of 5C12, 5H8, or phosphate buffered saline (PBS) and the sites of localization of labeled Stx2, were investigated 3, 24 and 48 hours later. The liver recorded statistically much higher concentrations of labeled Stx2 for groups receiving 5C12 and 5H8 antibodies after 3, 24 and 48 hours, as compared with the PBS group. In contrast, highest levels of labeled Stx2 were detected in the kidneys of the PBS group at all 3 sampling times. Mice receiving either of the two HuMAbs were fully protected against the lethal effect of Stx2, as compared with the fatal outcome of the control group. Conclusions The results suggest that HuMAbs 5C12 and 5H8 promoted hepatic accumulation and presumably clearance of toxin/antibody complexes, significantly diverting Stx2 localization in the kidneys, the target of Stx2 and the cause of HUS. This is in contrast to the fatal outcome of the control group receiving PBS. The results also confirm earlier observations that both HuMAbs are highly and equally protective against Stx2 intoxication in mice.
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- 2012
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8. Catalytic pyrolysis of Laminaria japonica over nanoporous catalysts using Py-GC/MS
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Jeon Jong-Ki, Jeong Kwang-Eun, Chae Ho-Jeong, Park Sung Hoon, Lee Hyung Won, and Park Young-Kwon
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Laminaria japonica ,hierarchical meso-MFI zeolite ,Al-MCM-48 ,Py-GC/MS ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Abstract The catalytic pyrolysis of Laminaria japonica was carried out over a hierarchical meso-MFI zeolite (Meso-MFI) and nanoporous Al-MCM-48 using pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). The effect of the catalyst type on the product distribution and chemical composition of the bio-oil was examined using Py-GC/MS. The Meso-MFI exhibited a higher activity in deoxygenation and aromatization during the catalytic pyrolysis of L. japonica. Meanwhile, the catalytic activity of Al-MCM-48 was lower than that of Meso-MFI due to its weak acidity.
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- 2011
9. In vitro and in vivo protective efficacies of antibodies that neutralize the RNA N-glycosidase activity of Shiga toxin 2
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Tzipori Saul, Lee Jongo, Singh Pradeep, Chapman-Bonofiglio Susan, Jeong Kwang-il, and Sheoran Abhineet S
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Immunologic diseases. Allergy ,RC581-607 - Abstract
Abstract Backgound Shiga toxin 2 (Stx2), one of two Stx liberated by Stx-producing Escherichia coli, is composed of an A subunit monomer and a B subunit pentamer, and is directly linked with hemolytic uremic syndrome in children. The pentameric B subunit binds to its cell surface receptor Gb3 for toxin internalization, and the A subunit follows intracellular retrograde transport to the cytosol where its RNA N-glycosidase activity (RNA-NGA) shuts down the protein synthesis, and leads to cell death. The present study investigated the ability of 19 Stx2 A subunit-specific human monoclonal antibodies (HuMAbs) to neutralize the RNA-NGA, and the association this neutralizing activity with protection of HeLa cells and mice against Stx2-induced death. Results The HuMAbs that were stronger inhibitors of RNA-NGA were also better at neutralizing Stx2 mediated HeLa cell death, and those that were weaker inhibitors of RNA-NGA activity were also weaker in protecting HeLa cells. These results suggest that the ability of an A subunit-specific antibody to block the RNA-NGA of the toxin is directly related to its ability to neutralize Stx2-mediated HeLa cell death. However, with the exception of the best RNA-NGA blocking antibodies 5C12 and 2F10, the efficacies of antibody neutralization of RNA-NGA of Stx2 did not correlate with their in vivo protective efficacies. The HuMAb 6C3, which neutralized RNA N-glycosidase activity of Stx2 less effectively than the HuMAbs 6D8 and 6B7, protected 100% of the mice against Stx2 challenge at 50 μg/mouse dose. In contrast, the HuMAbs 6D8 and 6B7, which neutralized RNA N-glycosidase activity of Stx2 more effectively than 6C3, protected 20% and 0% mice at that dose, respectively. Conclusions The neutralization efficiency of the RNA-NGA of Stx2 by A subunit-specific antibodies correlate strongly with their abilities to protect HeLa cells against Stx2-mediated toxicity but only the strongest RNA-NGA-neutralizing antibodies correlate very well with both protecting HeLa cells and mice against Stx2 challenge.
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- 2010
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10. Acid stress damage of DNA is prevented by Dps binding in Escherichia coli O157:H7
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Baumler David J, Hung Kai, Jeong Kwang, Byrd Jeffrey J, and Kaspar Charles W
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Microbiology ,QR1-502 - Abstract
Abstract Background Acid tolerance in Escherichia coli O157:H7 contributes to persistence in its bovine host and is thought to promote passage through the gastric barrier of humans. Dps (DNA-binding protein in starved cells) mutants of E. coli have reduced acid tolerance when compared to the parent strain although the role of Dps in acid tolerance is unclear. This study investigated the mechanism by which Dps contributes to acid tolerance in E. coli O157:H7. Results The results from this study showed that acid stress lead to damage of chromosomal DNA, which was accentuated in dps and recA mutants. The use of Bal31, which cleaves DNA at nicks and single-stranded regions, to analyze chromosomal DNA extracted from cells challenged at pH 2.0 provided in vivo evidence of acid damage to DNA. The DNA damage in a recA mutant further corroborated the hypothesis that acid stress leads to DNA strand breaks. Under in vitro assay conditions, Dps was shown to bind plasmid DNA directly and protect it from acid-induced strand breaks. Furthermore, the extraction of DNA from Dps-DNA complexes required a denaturing agent at low pH (2.2 and 3.6) but not at higher pH (>pH4.6). Low pH also restored the DNA-binding activity of heat-denatured Dps. Circular dichroism spectra revealed that at pH 3.6 and pH 2.2 Dps maintains or forms α-helices that are important for Dps-DNA complex formation. Conclusion Results from the present work showed that acid stress results in DNA damage that is more pronounced in dps and recA mutants. The contribution of RecA to acid tolerance indicated that DNA repair was important even when Dps was present. Dps protected DNA from acid damage by binding to DNA. Low pH appeared to strengthen the Dps-DNA association and the secondary structure of Dps retained or formed α-helices at low pH. Further investigation into the precise interplay between DNA protection and damage repair pathways during acid stress are underway to gain additional insight.
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- 2008
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11. H-NS controls metabolism and stress tolerance in Escherichia coli O157:H7 that influence mouse passage
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Ho Choi Sang, Vykhodets Boris, Baumler David J, Jeong Kwang-Cheol, Erol Irfan, and Kaspar Charles W
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Microbiology ,QR1-502 - Abstract
Abstract Background H-NS is a DNA-binding protein with central roles in gene regulation and nucleoid structuring in Escherichia coli. There are over 60 genes that are influenced by H-NS many of which are involved in metabolism. To determine the significance of H-NS-regulated genes in metabolism and stress tolerance, an hns mutant of E. coli O157:H7 was generated (hns::nptI, FRIK47001P) and its growth, metabolism, and gastrointestinal passage compared to the parent strain (43895) and strain FRIK47001P harboring pSC0061 which contains a functional hns and 90-bp upstream of the open-reading frame. Results The hns mutant grew slower and was non-motile in comparison to the parent strain. Carbon and nitrogen metabolism was significantly altered in the hns mutant, which was incapable of utilizing 42 carbon, and 19 nitrogen sources that the parent strain metabolized. Among the non-metabolized substrates were several amino acids, organic acids, and key metabolic intermediates (i.e., pyruvate) that limit carbon acquisition and energy generation. Growth studies determined that the parent strain grew in LB containing 14 to 15% bile or bile salts, while the hns mutant grew in 6.5 and 9% of these compounds, respectively. Conversely, log-phase cells of the hns mutant were significantly (p < 0.05) more acid tolerant than the parent strain and hns mutant complemented with pSC0061. In mouse passage studies, the parent strain was recovered at a higher frequency (p < 0.01) than the hns mutant regardless of whether log- or stationary-phase phase cells were orally administered. Conclusion These results demonstrate that H-NS is a powerful regulator of carbon and nitrogen metabolism as well as tolerance to bile salts. It is likely that the metabolic impairments and/or the reduced bile tolerance of the E. coli O157:H7 hns mutant decreased its ability to survive passage through mice. Collectively, these results expand the influence of H-NS on carbon and nitrogen metabolism and highlight its role in the ability of O157:H7 strains to respond to changing nutrients and conditions encountered in the environment and its hosts.
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- 2006
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12. Inter hospital external validation of interpretable machine learning based triage score for the emergency department using common data model.
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Yu JY, Kim D, Yoon S, Kim T, Heo S, Chang H, Han GS, Jeong KW, Park RW, Gwon JM, Xie F, Ong MEH, Ng YY, Joo HJ, and Cha WC
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- Adult, Humans, Retrospective Studies, Machine Learning, Hospitals, Triage methods, Emergency Service, Hospital
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Emergency departments (ED) are complex, triage is a main task in the ED to prioritize patient with limited medical resources who need them most. Machine learning (ML) based ED triage tool, Score for Emergency Risk Prediction (SERP), was previously developed using an interpretable ML framework with single center. We aimed to develop SERP with 3 Korean multicenter cohorts based on common data model (CDM) without data sharing and compare performance with inter-hospital validation design. This retrospective cohort study included all adult emergency visit patients of 3 hospitals in Korea from 2016 to 2017. We adopted CDM for the standardized multicenter research. The outcome of interest was 2-day mortality after the patients' ED visit. We developed each hospital SERP using interpretable ML framework and validated inter-hospital wisely. We accessed the performance of each hospital's score based on some metrics considering data imbalance strategy. The study population for each hospital included 87,670, 83,363 and 54,423 ED visits from 2016 to 2017. The 2-day mortality rate were 0.51%, 0.56% and 0.65%. Validation results showed accurate for inter hospital validation which has at least AUROC of 0.899 (0.858-0.940). We developed multicenter based Interpretable ML model using CDM for 2-day mortality prediction and executed Inter-hospital external validation which showed enough high accuracy., (© 2024. The Author(s).)
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- 2024
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13. N -retinylidene- N -retinylethanolamine degradation in human retinal pigment epithelial cells via memantine- and ifenprodil-mediated autophagy.
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Lee JR and Jeong KW
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N -methyl- D -aspartate (NMDA) receptors are ionic glutamine receptors involved in brain development and functions such as learning and memory formation. NMDA receptor inhibition is associated with autophagy activation. In this study, we investigated whether the NMDA receptor antagonists, memantine and ifenprodil, induce autophagy in human retinal pigment epithelial cells (ARPE-19) to remove Nretinylidene- N -retinylethanolamine (A2E), an intracellular lipofuscin component. Fluorometric analysis using labeled A2E (A2E-BDP) and confocal microscopic examination revealed that low concentrations of NMDA receptor antagonists, which did not induce cytotoxicity, significantly reduced A2E accumulation in ARPE-19 cells. In addition, memantine and ifenprodil activated autophagy in ARPE-19 cells as measured by microtubule-associated protein 1A/1B-light chain3-II formation and phosphorylated p62 protein levels. Further, to understand the correlation between memantine- and ifenprodil-mediated A2E degradation and autophagy, autophagy-related 5 (ATG5) was depleted using RNA interference. Memantine and ifenprodil failed to degrade A2E in ARPE-19 cells lacking ATG5. Taken together, our study indicates that the NMDA receptor antagonists, memantine and ifenprodil, can remove A2E accumulated in cells via autophagy activation in ARPE-19 cells.
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- 2023
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14. Histone modifications in drug-resistant cancers: From a cancer stem cell and immune evasion perspective.
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Jin ML and Jeong KW
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- Humans, Histones metabolism, Immune Evasion, Neoplastic Stem Cells metabolism, Histone Code, Neoplasms drug therapy, Neoplasms genetics
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The development and immune evasion of cancer stem cells (CSCs) limit the efficacy of currently available anticancer therapies. Recent studies have shown that epigenetic reprogramming regulates the expression of characteristic marker proteins and tumor plasticity associated with cancer cell survival and metastasis in CSCs. CSCs also possess unique mechanisms to evade external attacks by immune cells. Hence, the development of new strategies to restore dysregulated histone modifications to overcome cancer resistance to chemotherapy and immunotherapy has recently attracted attention. Restoring abnormal histone modifications can be an effective anticancer strategy to increase the therapeutic effect of conventional chemotherapeutic and immunotherapeutic drugs by weakening CSCs or by rendering them in a naïve state with increased sensitivity to immune responses. In this review, we summarize recent findings regarding the role of histone modifiers in the development of drug-resistant cancer cells from the perspectives of CSCs and immune evasion. In addition, we discuss attempts to combine currently available histone modification inhibitors with conventional chemotherapy or immunotherapy., (© 2023. The Author(s).)
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- 2023
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15. Response to "Comment on Comparison between the coronal diameters of the cervical spinal canal and spinal cord measured using computed tomography and magnetic resonance imaging in Korean patients".
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Jung JY, Lee SY, Jeong KW, and Ryu T
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- Humans, Magnetic Resonance Imaging, Neck, Republic of Korea, Spinal Cord diagnostic imaging, Spinal Canal diagnostic imaging, Spinal Canal pathology
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- 2023
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16. Giant and highly anisotropic magnetocaloric effects in single crystals of disordered-perovskite RCr 0.5 Fe 0.5 O 3 (R = Gd, Er).
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Shin HJ, Kim JS, Jeong KW, Kim JH, Lee N, and Choi YJ
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Magnetic anisotropy is crucial in examining suitable materials for magnetic functionalities because it affects their magnetic characteristics. In this study, disordered-perovskite RCr
0.5 Fe0.5 O3 (R = Gd, Er) single crystals were synthesized and the influence of magnetic anisotropy and additional ordering of rare-earth moments on cryogenic magnetocaloric properties was investigated. Both GdCr0.5 Fe0.5 O3 (GCFO) and ErCr0.5 Fe0.5 O3 (ECFO) crystallize in an orthorhombic Pbnm structure with randomly distributed Cr3+ and Fe3+ ions. In GCFO, the long-range order of Gd3+ moments emerges at a temperature of TGd (the ordering temperature of Gd3+ moments) = 12 K. The relatively isotropic nature of large Gd3+ moment originating from zero orbital angular momentum exhibits giant and virtually isotropic magnetocaloric effect (MCE), with a maximum magnetic entropy change of [Formula: see text] ≈ 50.0 J/kg·K. In ECFO, the highly anisotropic magnetizations result in a large rotating MCE characterized by a rotating magnetic entropy change [Formula: see text] = 20.8 J/kg·K. These results indicate that a detailed understanding of magnetically anisotropic characteristics is the key for exploring improved functional properties in disordered perovskite oxides., (© 2023. The Author(s).)- Published
- 2023
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17. A small molecule compound that inhibits blue light-induced retinal damage via activation of autophagy.
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Shin CY, Lee S, Jin HL, Fei X, Kang SW, Seo SY, and Jeong KW
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- Humans, Mice, Animals, Retinal Pigment Epithelium metabolism, Retinal Pigment Epithelium radiation effects, Cell Line, Autophagy physiology, Retina, Light
- Abstract
Dry age-related macular degeneration (AMD) is a type of disease that causes visual impairment due to changes in the macula located in the center of the retina. The accumulation of drusen under the retina is also a characteristic of dry AMD. In this study, we identified a compound (JS-017) that can potentially degrade N-retinylidene-N-retinylethanolamine (A2E), one of the components of lipofuscin, using fluorescence-based screening, which measures A2E degradation in human retinal pigment epithelial cells. JS-017 effectively degraded A2E in ARPE-19 cells and consequently suppressed the activation of the NF-κB signaling pathway and expression of inflammatory and apoptosis genes induced by blue light (BL). Mechanistically, JS-017 induced LC3-II formation and improved autophagic flux in ARPE-19 cells. Additionally, the A2E degradation activity of JS-017 was found to be decreased in autophagy-related 5 protein-depleted ARPE-19 cells, suggesting that autophagy was required for A2E degradation mediated by JS-017. Finally, JS-017 exhibited an improvement in BL-induced retinal damage measured through fundus examination in an in vivo retinal degeneration mouse model. The thickness of the outer nuclear layer and inner/external segments, which was decreased upon exposure to BL irradiation, was also restored upon JS-017 treatment. Altogether, we demonstrated that JS-017 protected human retinal pigment epithelium (RPE) cells from A2E and BL-induced damage by degrading A2E via the activation of autophagy. The results suggest the feasibility of a novel A2E-degrading small molecule as a therapeutic agent for retinal degenerative diseases., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)
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- 2023
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18. Spin-flip-driven anomalous Hall effect and anisotropic magnetoresistance in a layered Ising antiferromagnet.
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Oh DG, Kim JH, Kim MK, Jeong KW, Shin HJ, Hong JM, Kim JS, Moon K, Lee N, and Choi YJ
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The influence of magnetocrystalline anisotropy in antiferromagnets is evident in a spin flip or flop transition. Contrary to spin flops, a spin-flip transition has been scarcely presented due to its specific condition of relatively strong magnetocrystalline anisotropy and the role of spin-flips on anisotropic phenomena has not been investigated in detail. In this study, we present antiferromagnet-based functional properties on an itinerant Ising antiferromagnet Ca
0.9 Sr0.1 Co2 As2 . In the presence of a rotating magnetic field, anomalous Hall conductivity and anisotropic magnetoresistance are demonstrated, the effects of which are maximized above the spin-flip transition. Moreover, a joint experimental and theoretical study is conducted to provide an efficient tool to identify various spin states, which can be useful in spin-processing functionalities., (© 2023. The Author(s).)- Published
- 2023
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19. Synthesis and Structure Revision of Naturally Occurring Homoisoflavane (+)-Dracaeconolide B.
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Kwon S, Lee S, Hur J, Ko K, Fei X, Jeong KW, Sishtla K, Muniyandi A, Bae M, Corson TW, and Seo SY
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- Magnetic Resonance Spectroscopy, Molecular Structure, Plant Extracts chemistry, Resins, Plant chemistry, Stereoisomerism, Dracaena chemistry
- Abstract
Dracaeconolide B ( 1 ), a naturally occurring homoisoflavane, was isolated from the red resin of Dracaena cochinchinensis . Efforts have been made to elucidate the exact structure of compound 1 since it was confirmed that dracaeconolide B did not contain a 7-hydroxy-5,8-dimethoxy moiety. The structure of dracaeconolide B was revised by synthesis of three homoisoflavanes containing a 5,6,7-trioxygenated moiety each and analysis by NMR spectroscopy. The revised structure of dracaeconolide B was proposed as 3-(4-hydroxybenzyl)-7-hydroxy-5,6-dimethoxychromane. Noyori's Ru-catalyzed asymmetric transfer hydrogenation was used to synthesize (+)-dracaeconolide B. The absolute configuration of the compound was revised to S based on the results obtained by the electronic circular dichroism calculation. We examined the antiangiogenic activity of ( S )- and ( R )-dracaeconolide B and of synthetic 5,6,7- and 5,7,8-trioxygenated homoisoflavanes. The results can potentially help in the synthesis of related natural products and support drug discovery to treat neovascular eye diseases.
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- 2023
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20. Photooxidation of A2E by Blue Light Regulates Heme Oxygenase 1 Expression via NF-κB and Lysine Methyltransferase 2A in ARPE-19 Cells.
- Author
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Shin CY and Jeong KW
- Abstract
Background: N-retinylidene-N-retinylethanolamine (A2E) is a component of drusen that accumulates in retinal cells and induces oxidative stress through photooxidation, such as blue light (BL). We found that the heme oxygenase 1 ( HMOX1 ) gene responds sensitively to photooxidation by the BL of A2E in retinal pigment epithelial (RPE) cells, and we sought to identify the transcription factors and coactivators involved in the upregulation of HMOX1 by A2E and BL. Methods: A2E-laden human RPE cells (ARPE-19) were exposed to BL (430 nm). RNA sequencing was performed to identify genes responsive to BL exposure. Chromatin immunoprecipitation and RT-qPCR were performed to determine the regulation of HMOX1 transcription. Clinical transcriptome data were used to evaluate HMOX1 expression in patients with age-related macular degeneration (AMD). Results: In ARPE-19 cells, the expression of HMOX1 , one of the NF-κB target genes, was significantly increased by A2E and BL. The binding of RELA and RNA polymerase II to the promoter region of HMOX1 was significantly increased by A2E and BL. Lysine methyltransferase 2A (MLL1) plays an important role in H3K4me3 methylation, NF-κB recruitment, chromatin remodeling at the HMOX1 promoter, and, subsequently, HMOX1 expression. The retinal tissues of patients with late-stage AMD showed significantly increased expression of HMOX1 compared to normal retinal tissues. In addition, the expression levels of MLL1 and HMOX1 in retinal tissues were correlated. Conclusions: Taken together, our results suggest that BL induces HMOX1 expression by activating NF-κB and MLL1 in RPE cells., Competing Interests: The authors declare no conflict of interest.
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- 2022
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21. NMDA Receptor Antagonists Degrade Lipofuscin via Autophagy in Human Retinal Pigment Epithelial Cells.
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Lee JR and Jeong KW
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- Autophagy physiology, Epithelial Cells, Humans, Receptors, N-Methyl-D-Aspartate metabolism, Retinal Pigments metabolism, Retinal Pigments pharmacology, Retinoids metabolism, Retinoids toxicity, Lipofuscin metabolism, Lipofuscin pharmacology, Retinal Pigment Epithelium metabolism
- Abstract
Background and Objectives: Age-related macular degeneration is a slow-progressing disease in which lipofuscin accumulates in the retina, causing inflammation and apoptosis of retinal pigment epithelial (RPE) cells. This study aimed to identify N -methyl-D-aspartate (NMDA) signaling as a novel mechanism for scavenging N -retinylidene- N -retinylethanolamine (A2E), a component of ocular lipofuscin, in human RPE cells. Materials and Methods: A2E degradation assays were performed in ARPE-19 cells using fluorescently labeled A2E. The autophagic activity in ARPE-19 cells was measured upon blue light (BL) exposure, after A2E treatment. Autophagy flux was determined by measuring LC3-II formation using immunoblotting and confocal microscopy. To determine whether autophagy via the NMDA receptor is involved in A2E clearance, ATG5-deficient cells were used. Results: Ro 25-6981, an NR2B-selective NMDA receptor antagonist, effectively cleared A2E. Ro 25-6981 reduced A2E accumulation in the lysosomes of ARPE-19 cells at sub-cytotoxic concentrations, while increasing the formation of LC3-II and decreasing p62 protein levels in a concentration-dependent manner. The autophagic flux monitored by RFP-GFP-LC3 and bafilomycin A1 assays was significantly increased by Ro 25-6981. A2E clearance by Ro 25-6981 was abolished in ATG5-depleted ARPE-19 cells, suggesting that A2E degradation by Ro 25-6981 was mediated by autophagy. Furthermore, treatment with other NMDA receptor antagonists, CP-101,606 and AZD6765, showed similar effects on autophagy activation and A2E degradation in ARPE-19 cells. In contrast, glutamate, an NMDA receptor agonist, exhibited a contrasting effect, suggesting that both the activation of autophagy and the degradation of A2E by Ro 25-6981 in ARPE-19 cells occur through inhibition of the NMDA receptor pathway. Conclusions: This study demonstrates that NMDA receptor antagonists degrade lipofuscin via autophagy in human RPE cells and suggests that NMDA receptor antagonists could be promising new therapeutics for retinal degenerative diseases.
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- 2022
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22. Comparison between the coronal diameters of the cervical spinal canal and spinal cord measured using computed tomography and magnetic resonance imaging in Korean patients.
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Lee SY, Kim IY, Jeong KW, Ryu T, Kwak SK, and Jung JY
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- Humans, Magnetic Resonance Imaging, Republic of Korea, Retrospective Studies, Spinal Cord, Tomography, X-Ray Computed, Spinal Canal diagnostic imaging, Spinal Canal pathology, Spinal Puncture
- Abstract
Background: If the proportion of the spinal cord in the epidural space can be determined under C-arm fluoroscopy during cervical epidural block, a safe entry point for the epidural needle can be established. The aim of this study was the measurement of the cord to canal transverse diameter ratio of each cervical spines., Methods: We retrospectively evaluated the imaging data of 100 patients who underwent both cervical computed tomography (CT) and cervical magnetic resonance imaging (MRI) at our hospital. We measured the diameters of the spinal canal and spinal cord from the 3rd cervical vertebra to the 1st thoracic vertebra (T1) at each level by using the patients' cervical CT and MRI images. The spinal cord and spinal canal diameters were measured in the transverse plane of the cervical MRI and CT images, respectively., Results: The spinal cord to spinal canal diameter ratio was the highest at the 4th and 5th cervical vertebrae (0.64 ± 0.07) and the lowest at T1 (0.55 ± 0.06, 99% CI [0.535, 0.565]., Conclusions: Our findings suggest that the cord to canal transverse diameter ratio could be used as a reference to reduce direct spinal cord injuries during cervical epidural block under C-arm fluoroscopy. In the C-arm fluoroscopic image, if an imaginary line connecting the left and right innermost lines of the pedicles of T1 is drawn and if the needle is inserted into the outer one-fifth of the left and right sides, the risk of puncturing the spinal cord would be relatively reduced.
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- 2022
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23. Spin-flip-driven reversal of the angle-dependent magnetic torque in layered antiferromagnetic Ca 0.9 Sr 0.1 Co 2 As 2 .
- Author
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Kim JH, Kim MK, Jeong KW, Shin HJ, Hong JM, Kim JS, Moon K, Lee N, and Choi YJ
- Abstract
Spin-flip transition can occur in antiferromagnets with strong magnetocrystalline anisotropy, inducing a significant modification of the anisotropic magnetic properties through phase conversion. In contrast to ferromagnets, antiferromagnets have not been thoroughly examined in terms of their anisotropic characteristics. We investigated the magnetic-field and angle-dependent magnetic properties of Ising-type antiferromagnetic Ca
0.9 Sr0.1 Co2 As2 using magnetic torque measurements. An A-type antiferromagnetic order emerges below TN = 97 K aligned along the magnetically easy c-axis. The reversal of the angle-dependent torque across the spin-flip transition was observed, revealing the strong influence of the magnetocrystalline anisotropy on the magnetic properties. Based on the easy-axis anisotropic spin model, we theoretically generated torque data and identified specific spin configurations associated with the magnetic torque variation in the presence of a rotating magnetic field. Our results enrich fundamental and applied research on diverse antiferromagnetic compounds by shedding new light on the distinct magnetic features of the Ising-type antiferromagnet., (© 2022. The Author(s).)- Published
- 2022
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24. SETD1A-SOX2 axis is involved in tamoxifen resistance in estrogen receptor α-positive breast cancer cells.
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Jin ML, Yang L, and Jeong KW
- Subjects
- Drug Resistance, Neoplasm, Estrogen Receptor alpha genetics, Estrogen Receptor alpha metabolism, Female, Histone-Lysine N-Methyltransferase genetics, Histone-Lysine N-Methyltransferase metabolism, Humans, MCF-7 Cells, SOXB1 Transcription Factors genetics, Breast Neoplasms drug therapy, Breast Neoplasms genetics, Breast Neoplasms metabolism, Tamoxifen pharmacology, Tamoxifen therapeutic use
- Abstract
Rationale : Approximately 30-40% of estrogen receptor (ER)-positive breast cancer (BC) cases recur after tamoxifen therapy. Thus, additional studies on the mechanisms underlying tamoxifen resistance and more specific prognostic biomarkers are required. In this study, we investigated the role of the SET domain containing 1A (SETD1A), a histone H3-lysine 4 (H3K4) methyltransferase, in the development of tamoxifen resistance in BC. Methods : The relationship between tamoxifen resistance and SETD1A protein level was investigated using resistant cell lines derived from the parent BC cells. Biochemical and molecular assays, such as RNA-sequencing, reverse transcription-quantitative polymerase chain reaction, chromatin-immunoprecipitation, and protein-binding assays, were used to identify the SETD1A target gene in tamoxifen-resistant BC cells. Additionally, the role of SETD1A in cancer stem cells (CSCs) was investigated using CSCs isolated from tamoxifen-resistant BC cells. Comprehensive transcriptome analysis and immunofluorescence staining using clinical datasets and tissue microarray were performed to determine the correlation between the expression of the SETD1A-SRY-box transcription factor 2 (SOX2) pair and recurrence in tamoxifen-treated patients with BC. Results : SETD1A was expressed at higher levels in tamoxifen-resistant BC cells than in primary BC cells. Notably, SETD1A-depleted tamoxifen-resistant MCF-7 cells showed restored sensitivity to tamoxifen, whereas SETD1A overexpression in MCF-7 cells resulted in decreased sensitivity. SETD1A is recruited to the SOX2 gene via its interaction with SOX2, thereby enhancing the expression of SOX2 genes in tamoxifen-resistant BC cells. The growth of tamoxifen-resistant cells and CSCs was effectively suppressed by SETD1A knockdown. In addition, high levels of SETD1A and SOX2 were significantly correlated with a low survival rate in patients with ER-positive tamoxifen-resistant BC. Conclusion : Our findings provide the first evidence of the critical role of the SETD1A-SOX2 axis in tamoxifen-resistant BC cells, implying that SETD1A may serve as a molecular target and prognostic indicator of a therapeutic response in patients with tamoxifen-resistant BC., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)
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- 2022
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25. Transcriptome Analysis of Long-Term Exposure to Blue Light in Retinal Pigment Epithelial Cells.
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Jin HL and Jeong KW
- Abstract
Dry age-related macular degeneration (AMD) is a type of progressive blindness that is primarily due to dysfunction and the loss of retinal pigment epithelium (RPE). The accumulation of N-retinylidene-N-retinylethanolamine (A2E), a by-product of the visual cycle, causes RPE and photoreceptor degeneration that impairs vision. Genes associated with dry AMD have been identified using a blue light model of A2E accumulation in the retinal pigment epithelium and transcriptomic studies of retinal tissue from patients with AMD. However, dry macular degeneration progresses slowly, and current approaches cannot reveal changes in gene transcription according to stages of AMD progression. Thus, they are limited in terms of identifying genes responsible for pathogenesis. Here, we created a model of long-term exposure to identify temporally-dependent changes in gene expression induced in human retinal pigment epithelial cells (ARPE-19) exposed to blue light and a non-cytotoxic dose of A2E for 120 days. We identified stage-specific genes at 40, 100, and 120 days, respectively. The expression of genes corresponding to epithelial-mesenchymal transition (EMT) during the early stage, glycolysis and angiogenesis during the middle stage, and apoptosis and inflammation pathways during the late stage was significantly altered by A2E and blue light. Changes in the expression of genes at the late stages of the EMT were similar to those found in human eyes with late-stage AMD. Our results provide further insight into the pathogenesis of dry AMD induced by blue light and a novel model in vitro with which relevant genes can be identified in the future.
- Published
- 2022
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26. Protective Effect of Ribes nigrum Extract against Blue Light-Induced Retinal Degeneration In Vitro and In Vivo.
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Shin CY, Lee MH, Kim HM, Chung HC, Kim DU, Lee JH, and Jeong KW
- Abstract
Although blackcurrant has several health benefits, such as antioxidant and anti-inflammatory properties, its effects on the retina remain unclear. In this study, we investigated the efficacy of black currant extract (BCE) in an in vitro and in vivo model of dry age-related macular degeneration (AMD) induced by blue light. Dry macular degeneration is characterized by the abnormal accumulation of lipofuscin (e.g., N-retinylidene-N-retinylethanolamine, A2E) in the retina. Blue light (BL) significantly decreased the viability of A2E-laden human retinal pigment epithelial cells (ARPE-19). However, BCE treatment protected ARPE-19 cells from A2E and BL. A2E, which is oxidized by blue light, generates reactive oxygen species in RPE cells. Treatment with BCE significantly decreased (80.8%) reactive oxygen species levels induced by A2E and BL in a concentration-dependent manner. BCE inhibited A2E accumulation in ARPE-19 cells and significantly downregulated the expression of genes increased by A2E and BL in ARPE-19 cells. In vivo, oral administration of BCE (25-100 mg/kg) ameliorated ocular lesions of BL-induced retinal damage in a mouse model and rescued the thickness of the whole retina, photoreceptor segment layer, outer nuclear layer, and inner nuclear layer. The decrease in the number of nuclei in the outer nuclear layer induced by BL was also rescued by BCE. Additionally, BCE administration rescued (40.0%) the BL-induced reduction in the expression level of superoxide dismutase 1. Taken together, our results suggest that BCE may have preventive and therapeutic effects on dry AMD through its antioxidant activity and inhibition of lipofuscin accumulation in the retina.
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- 2022
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27. Therapeutic effect of intradiscal pulsed radiofrequency on internal disc disruption: A case report.
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Kim DH, Jeong KW, Jo W, Lee SY, Im JA, and Jung JY
- Subjects
- Adult, Female, Humans, Intervertebral Disc Degeneration diagnostic imaging, Intervertebral Disc Degeneration therapy, Intervertebral Disc Displacement diagnostic imaging, Low Back Pain etiology, Magnetic Resonance Imaging, Treatment Outcome, Intervertebral Disc Displacement therapy, Low Back Pain therapy, Pulsed Radiofrequency Treatment methods
- Abstract
Rationale: Discogenic low back pain often persists despite medication and medical intervention. In this study, intradiscal pulsed radiofrequency (PRF) was performed in a patient with discogenic low back pain who did not respond to oral medication, posterior medial branch block, epidural steroid injection, and percutaneous epidural adhesiolysis., Patient Concerns: A 28-year-old woman visited a pain clinic complaining of low back pain that was scored 8 out of 10 on a numerical rating scale. Her pain was present in any position throughout the day and worsened in the sitting position., Diagnoses: Magnetic resonance imaging showed L5-S1 internal discal disruption. Based on the medical history, physical examination, and magnetic resonance imaging, we determined that her pain originated from the L5-S1 disc., Interventions: We performed an intradiscal PRF on the affected disc under C-arm fluoroscopy guidance. PRF was performed at 5 Hz, 20-ms pulse width, and 70 V for 15 minutes while ensuring that the electrode tip temperature was maintained below 42°C., Outcomes: Immediately after the procedure, the patient's pain subsided. At the 1-month follow-up visit, the patient reported complete relief of her low back pain. The Oswestry disability index, which indicates the degree of disability, improved significantly. She also reported that she could sit for long periods because the pain was reduced. No adverse effects from the procedure were found., Lessons: Applying intradiscal PRF seems an effective and safe technique for treating discogenic low back pain., Competing Interests: The authors have no conflicts of interests to disclose., (Copyright © 2022 the Author(s). Published by Wolters Kluwer Health, Inc.)
- Published
- 2022
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28. Behavior of magnetoelectric hysteresis and role of rare earth ions in multiferroicity in double perovskite Yb 2 CoMnO 6 .
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Kim JH, Jeong KW, Oh DG, Shin HJ, Hong JM, Kim JS, Moon JY, Lee N, and Choi YJ
- Abstract
Double-perovskite multiferroics have been investigated because alternating orders of magnetic ions act as distinct magnetic origins for ferroelectricity. In Yb
2 CoMnO6 , the frustrated antiferromagnetic order emerging at TN = 52 K induces ferroelectric polarization perpendicular to the c axis through cooperative O2- shifts via the symmetric exchange striction. In our detailed measurements of the magnetoelectric properties of single-crystalline Yb2 CoMnO6 , we observe full ferromagnetic-like hysteresis loops that are strongly coupled to the dielectric constant and ferroelectric polarization at various temperatures below TN . Unlike Lu2 CoMnO6 with non-magnetic Lu3+ ions, we suggest the emergence of additional ferroelectric polarization along the c axis below the ordering temperature of magnetic Yb3+ ions, TYb ≈ 20 K, based on the spin structure established from recent neutron diffraction experiments. While the proposed description for additional ferroelectricity, ascribed to the symmetric exchange striction between Yb3+ and Co2+ /Mn4+ magnetic moments, is clearly given, anomalies of dielectric constants along the c axis are solely observed. Our interesting findings on magnetoelectric hysteresis and the possible development of additional ferroelectricity reveal notable characteristics of double perovskites and provide essential guidance for the further examination of magnetoelectric functional properties., (© 2021. The Author(s).)- Published
- 2021
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29. FLII and MLL1 Cooperatively Regulate Aryl Hydrocarbon Receptor-Mediated Transcription in ARPE-19 Cells.
- Author
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Jeong KW
- Subjects
- Cell Line, Chromatin Immunoprecipitation, Cytochrome P-450 CYP1A1 metabolism, Gene Expression Profiling, Humans, Protein Binding, Transcription, Genetic, Basic Helix-Loop-Helix Transcription Factors metabolism, Epithelial Cells metabolism, Gene Expression Regulation, Histone-Lysine N-Methyltransferase metabolism, Microfilament Proteins metabolism, Myeloid-Lymphoid Leukemia Protein metabolism, Receptors, Aryl Hydrocarbon metabolism, Retinal Pigment Epithelium metabolism, Trans-Activators metabolism, Transcriptional Activation
- Abstract
Aryl hydrocarbon receptors (AHRs), a class of ligand-dependent nuclear receptors that regulate cellular responses by inducing the expression of various target genes in response to external signals, are implicated in maintaining retinal tissue homeostasis. Previous studies have shown that the regulation of AHR-induced gene expression requires transcriptional co-regulators. However, it is not yet clear how chromatin remodelers, histone methyltransferases and coactivators interact during AHR-mediated gene expression in human retinal cells. In this study, we reveal that the histone methyltransferase MLL1 and the coactivator FLII are involved in AHR-mediated gene expression in retinal pigment epithelial cells. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) significantly increased the expression of CYP1A1, CYP1B1 and AHRR in ARPE-19 cells, whereas FLII or MLL1 depletion significantly reduced the expression of these genes induced by TCDD. Mechanistically, FLII binds to AHR in a ligand-dependent manner in ARPE-19 cells. In particular, the binding of FLII to MLL1 occurs through the GelB domain of FLII. In addition, MLL1 binds to AHR in a ligand-independent manner. FLII is involved in the recruitment of the BRG1 chromatin remodeler and MLL1 histone methyltransferase to the AHR-regulated CYP1A1 gene region in ARPE-19 cells and consequently, plays an important role in RNA polymerase II binding and transcriptional activity by modulating chromatin accessibility. Our results identify the functions and mechanisms of action of FLII and MLL1 in AHR-induced gene expression in human retinal pigment epithelial cells.
- Published
- 2021
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30. Histone H3K4 Methyltransferases as Targets for Drug-Resistant Cancers.
- Author
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Yang L, Jin M, and Jeong KW
- Abstract
The KMT2 (MLL) family of proteins, including the major histone H3K4 methyltransferase found in mammals, exists as large complexes with common subunit proteins and exhibits enzymatic activity. SMYD, another H3K4 methyltransferase, and SET7/9 proteins catalyze the methylation of several non-histone targets, in addition to histone H3K4 residues. Despite these structural and functional commonalities, H3K4 methyltransferase proteins have specificity for their target genes and play a role in the development of various cancers as well as in drug resistance. In this review, we examine the overall role of histone H3K4 methyltransferase in the development of various cancers and in the progression of drug resistance. Compounds that inhibit protein-protein interactions between KMT2 family proteins and their common subunits or the activity of SMYD and SET7/9 are continuously being developed for the treatment of acute leukemia, triple-negative breast cancer, and castration-resistant prostate cancer. These H3K4 methyltransferase inhibitors, either alone or in combination with other drugs, are expected to play a role in overcoming drug resistance in leukemia and various solid cancers.
- Published
- 2021
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31. Clinical Feasibility of Fully Sintered (Y, Nb)-TZP for CAD-CAM Single-Unit Restoration: A Pilot Study.
- Author
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Jeong KW, Yoon HI, Lee JH, Yeo IL, Kim DJ, and Han JS
- Abstract
Fifteen participants (9 male, 6 female) received a total of 15 monolithic single restorations made from fully sintered (Y, Nb)-TZP (tetragonal zirconia polycrystal) block. The restorations were clinically evaluated for survival, success rate, and periodontal probing depths 6 months after the insertion of the restorations. Esthetic, functional, and biological evaluations were also performed over a 6-month follow-up period. The survival and success rates of the single-unit restorations were 100%. The periodontal probing depth values ranged from 1 to 3 mm. No complications with regard to functional and biological properties were observed after 6 months. The postoperative sensitivity was only a transient phenomenon. The fully sintered (Y, Nb)-TZP single-unit restoration showed highly acceptable quality with successful clinical performance over 6 months.
- Published
- 2021
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32. Influence of Preaging Temperature on the Indentation Strength of 3Y-TZP Aged in Ambient Atmosphere.
- Author
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Jeong KW, Han JS, Yang GU, and Kim DJ
- Abstract
Yttria-stabilized zirconia (3Y-TZP) containing 0.25% Al
2 O3 , which is resistant to low temperature degradation (LTD), was aged for 10 h at 130-220 °C in air. The aged specimens were subsequently indented at loads ranging from 9.8 to 490 N using a Vickers indenter. The influence of preaging temperature on the biaxial strength of the specimens was investigated to elucidate the relationship between the extent of LTD and the strength of zirconia restorations that underwent LTD. The indented strength of the specimens increased as the preaging temperature was increased higher than 160 °C, which was accompanied by extensive t-ZrO2 (t) to m-ZrO2 (m) and c-ZrO2 (c) to r-ZrO2 (r) phase transformations. The influence of preaging temperature on the indented strength was rationalized by the residual stresses raised by the t→m transformation and the reversal of tensile residual stress on the aged specimen surface due to the indentation. The results suggested that the longevity of restorations would not be deteriorated if the aged restorations retain compressive residual stress on the surface, which corresponds to the extent of t→m phase transformation less than 52% in ambient environment.- Published
- 2021
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33. Solanum melongena L. Extract Protects Retinal Pigment Epithelial Cells from Blue Light-Induced Phototoxicity in In Vitro and In Vivo Models.
- Author
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Pham TNM, Shin CY, Park SH, Lee TH, Ryu HY, Kim SB, Auh K, and Jeong KW
- Subjects
- Animals, Disease Models, Animal, Epithelial Cells drug effects, Light, Male, Mice, Mice, Inbred BALB C, Plant Extracts metabolism, Retinal Pigment Epithelium metabolism, Dermatitis, Phototoxic prevention & control, Plant Extracts pharmacology, Retinal Pigment Epithelium drug effects, Retinal Pigments metabolism, Solanum melongena
- Abstract
N-retinylidene-N-retinylethanolamine (A2E) accumulation in the retina is a prominent marker of retinal degenerative diseases. Blue light exposure is considered as an important factor contributing to dry age-related macular degeneration (AMD). Eggplant and its constituents have been shown to confer health benefits, but their therapeutic effects on dry AMD remain incompletely understood. In this study, we showed that an extract of Solanum melongena L. (EPX) protected A2E-laden ARPE-19 cells against blue light-induced cell death via attenuating reactive oxygen species. Transcriptomic analysis demonstrated that blue light modulated the expression of genes associated with stress response, inflammation, and cell death, and EPX suppressed the inflammatory pathway induced by blue light in A2E-laden ARPE-19 cells by inhibiting the nuclear translocation of nuclear factor kappa B and transcription of pro-inflammatory genes ( CXCL8 and IL1B ). The degradation of intracellular A2E was considered the major mechanism underlying the protective effect of EPX. Moreover, chlorogenic acid isolated from EPX exerted protective effects against blue light-induced cell damage in A2E-laden ARPE-19 cells. In vivo, EPX administration in BALB/c mice reduced the fundus damage and degeneration of the retinal layer in a blue light-induced retinal damage model. Collectively, our findings suggest the potential role of Solanum melongena L. extract for AMD treatment.
- Published
- 2021
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34. Fatty Acid Derivatives Isolated from the Oil of Persea americana (Avocado) Protects against Neomycin-Induced Hair Cell Damage.
- Author
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Park S, Jeong SY, Nam YH, Park JH, Rodriguez I, Shim JH, Yasmin T, Kwak HJ, Oh Y, Oh M, Lee KW, Lee JS, Kim DH, Park YH, Moon IS, Choung SY, Jeong KW, Hong BN, Kim SH, and Kang TH
- Abstract
Avocado oil is beneficial to human health and has been reported to have beneficial effects on sensorineural hearing loss (SNHL). However, the compounds in avocado oil that affect SNHL have not been identified. In this study, we identified 20 compounds from avocado oil, including two new and 18 known fatty acid derivatives, using extensive spectroscopic analysis. The efficacy of the isolated compounds for improving SNHL was investigated in an ototoxic zebrafish model. The two new compounds, namely (2 R ,4 R ,6 Z )-1,2,4-trihydroxynonadec-6-ene and (2 R ,4 R )-1,2,4-trihydroxyheptadecadi-14,16-ene (compounds 1 and 2), as well as compounds 7, 9, 14, 17 and 19 showed significant improvement in damaged hair cells in toxic zebrafish. These results led to the conclusion that compounds from avocado oil as well as oil itself have a regenerative effect on damaged otic hair cells in ototoxic zebrafish.
- Published
- 2021
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35. SETD1A Promotes Proliferation of Castration-Resistant Prostate Cancer Cells via FOXM1 Transcription.
- Author
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Yang L, Jin M, Park SJ, Seo SY, and Jeong KW
- Abstract
Androgen deprivation therapy eventually leads to the development of castration-resistant prostate cancer (CRPC). Here, we demonstrate for the first time that the histone H3K4 methyltransferase SETD1A is a major regulator for the proliferation of metastatic CRPC (mCRPC). The expression of SETD1A was significantly correlated with the survival rate of patients with prostate cancer. SETD1A, which is expressed at a higher level in mCRPC than in primary prostate cancer cells, promotes the expression of FOXM1 , a gene encoding a cell proliferation-specific transcription factor. SETD1A is recruited to the promoter region of FOXM1 (forkhead box M1) upon binding to E2F1, a protein that regulates the transcription of FOXM1 and contributes to the trimethylation of H3K4 in the FOXM1 promoter region. In addition, SETD1A is essential for the expression of stem cell factor (e.g., OCT4, octamer-binding transcription factor 4) and stem cell formation in mCRPC, suggesting the importance of SETD1A expression in mCRPC tumor formation. Notably, poor prognosis is associated with high expression of the SETD1A-FOXM1 pair in clinical data sets. Therefore, our study suggests that SETD1A plays an important role in the proliferation of mCRPC by regulating FOXM1 transcription.
- Published
- 2020
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36. MLL2 regulates glucocorticoid receptor-mediated transcription of ENACα in human retinal pigment epithelial cells.
- Author
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Yang L, Jin M, Jung N, and Jeong KW
- Subjects
- Binding Sites, Cell Line, Chromatin metabolism, Chromatin Assembly and Disassembly drug effects, Dexamethasone pharmacology, Gene Expression Regulation, Humans, DNA-Binding Proteins metabolism, Epithelial Cells metabolism, Epithelial Sodium Channels metabolism, Neoplasm Proteins metabolism, Receptors, Glucocorticoid metabolism, Retinal Pigment Epithelium cytology, Transcription, Genetic
- Abstract
Glucocorticoids require the glucocorticoid receptor (GR), a type of ligand-dependent nuclear receptor to transmit their downstream effects. Upon glucocorticoid binding, GR associates with glucocorticoid response elements (GREs) and recruits other transcriptional coregulators to activate or repress target gene transcription. Many SET-domain family proteins have been demonstrated to contribute to GR-mediated transcriptional activity. However, whether histone H3K4-specific methyltransferase plays a cell-type-specific role in GR transcriptional regulation remains poorly understood. In this report, we examined MLL2 (KMT2D), a histone-lysine methyltransferase that catalyzes histone H3 lysine 4 methylation (H3K4me). Furthermore, we demonstrated that MLL2 specifically regulates the transcription of some GR target genes (e.g., ENACα and FLJ20371) in ARPE-19 cells, but has no effect in A549 cells. Mechanistically, co-immunoprecipitation assays revealed that MLL2 is associated with GR in a ligand-independent manner in APRE-19 cells. Moreover, chromatin immunoprecipitation analyses demonstrated that MLL2 could co-occupy glucocorticoid response elements (GREs) of GR target genes along with GR following Dex stimulation. Finally, the FAIRE-qPCR results illustrated that MLL2 is pivotal in establishing chromatin structure accessibility at the GREs of ARPE-19 specific genes in the presence of Dex. Taken together, our study determined that MLL2 regulates GR-mediated transcription in a cell-type-specific manner, and we provide a molecular mechanism to explain the specific role of MLL2 in regulating GR target gene expression in ARPE-19 cells., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)
- Published
- 2020
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37. Protective Mechanisms of Avocado Oil Extract Against Ototoxicity.
- Author
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Pham TNM, Jeong SY, Kim DH, Park YH, Lee JS, Lee KW, Moon IS, Choung SY, Kim SH, Kang TH, and Jeong KW
- Subjects
- Autophagy drug effects, Autophagy genetics, Cells, Cultured, Cytokines metabolism, Gene Expression drug effects, Glutathione metabolism, Hair Cells, Auditory, Inner drug effects, Hair Cells, Auditory, Inner pathology, Humans, Inflammation Mediators metabolism, Metabolic Detoxication, Phase I genetics, Ototoxicity pathology, Oxidative Stress genetics, Tumor Necrosis Factor-alpha metabolism, Aminoglycosides adverse effects, Anti-Bacterial Agents adverse effects, Ototoxicity drug therapy, Ototoxicity etiology, Ototoxicity genetics, Persea chemistry, Plant Oils pharmacology, Plant Oils therapeutic use
- Abstract
Despite the excellent antimicrobial activity of aminoglycoside antibiotics, permanent inner ear damage associated with the use of these drugs has resulted in the need to develop strategies to address the ototoxic risk given their widespread use. In a previous study, we showed that avocado oil protects ear hair cells from damage caused by neomycin. However, the detailed mechanism by which this protection occurs is still unclear. Here, we investigated the auditory cell-protective mechanism of enhanced functional avocado oil extract (DKB122). RNA sequencing followed by pathway analysis revealed that DKB122 has the potential to enhance the expression of detoxification and antioxidant genes associated with glutathione metabolism (Hmox4, Gsta4, Mgst1, and Abcc3) in HEI-OC1 cells. Additionally, DKB122 effectively decreased ROS levels, resulting in the inhibition of apoptosis in HEI-OC1 cells. The expression of the inflammatory genes that encode chemokines and interleukins was also downregulated by DKB122 treatment. Consistent with these results, DKB122 significantly inhibited p65 nuclear migration induced by TNF-α or LPS in HEI-OC1 cells and THP-1 cells and the expression of inflammatory chemokine and interleukin genes induced by TNF-α was significantly reduced. Moreover, DKB122 treatment increased LC3-II and decreased p62 in HEI-OC1 cells, suggesting that DKB122 increases autophagic flux. These results suggest that DKB122 has otoprotective effects attributable to its antioxidant activity, induction of antioxidant gene expression, anti-inflammatory activity, and autophagy activation.
- Published
- 2020
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38. Cell-specific expression of ENACα gene by FOXA1 in the glucocorticoid receptor pathway.
- Author
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Chung YS, Jin HL, and Jeong KW
- Subjects
- A549 Cells, Dexamethasone pharmacology, Epithelial Sodium Channels genetics, Gene Expression Regulation, Neoplastic, Glucocorticoids pharmacology, Hepatocyte Nuclear Factor 3-alpha genetics, Humans, Lung Neoplasms genetics, Receptors, Glucocorticoid agonists, Retinal Pigment Epithelium drug effects, Signal Transduction, Tacrolimus Binding Proteins genetics, Epithelial Sodium Channels metabolism, Hepatocyte Nuclear Factor 3-alpha metabolism, Lung Neoplasms metabolism, Receptors, Glucocorticoid metabolism, Retinal Pigment Epithelium metabolism, Tacrolimus Binding Proteins metabolism
- Abstract
Introduction: The glucocorticoid receptor (GR) is one of the most widely studied ligand-dependent nuclear receptors. The combination of transcriptional regulatory factors required for the expression of individual genes targeted by GR varies across cell types; however, the mechanisms underlying this cell type-specific regulation of gene expression are not yet clear., Methods: Here, we investigated genes regulated by GR in two different cell lines, A549 and ARPE-19, and examined how gene expression varied according to the effect of pioneer factors using RNA-seq and RT-qPCR., Results: Our RNA-seq results identified 19 and 63 genes regulated by GR that are ARPE-19-specific and A549-specific, respectively, suggesting that GR induces the expression of different sets of genes in a cell type-specific manner. RT-qPCR confirmed that the epithelial sodium channel ( ENACα ) gene is an ARPE-19 cell-specific GR target gene, whereas the FK506 binding protein 5 ( FKBP5 ) gene was A549 cell-specific. There was a significant decrease in ENACα expression in FOXA1-deficient ARPE-19 cells, suggesting that FOXA1 might function as a pioneer factor enabling the selective expression of ENACα in ARPE-19 cells but not in A549 cells., Conclusion: These findings indicate that ENACα expression in ARPE-19 cells is regulated by FOXA1 and provide insights into the molecular mechanisms of cell type-specific expression of GR-regulated genes.
- Published
- 2020
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39. Photoactivation of N-retinylidene-N-retinylethanolamine compromises autophagy in retinal pigmented epithelial cells.
- Author
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Jeong SY, Gu X, and Jeong KW
- Subjects
- Acetylcysteine pharmacology, Cell Line, Humans, Light, Lysosomes drug effects, Microtubule-Associated Proteins metabolism, Reactive Oxygen Species metabolism, Retinoids radiation effects, Autophagy drug effects, Epithelial Cells drug effects, Retinal Pigment Epithelium drug effects, Retinoids toxicity
- Abstract
As a part of the aging process, N-retinylidene-N-retinylethanolamine (A2E) accumulates in the retina to activate autophagy in retinal pigmented epithelial cells. However, the effect of A2E photoactivation on autophagy, which is more clinically relevant, still remains unclear. Here, we investigated the effect of blue light (BL)-activated A2E on autophagy in human retinal pigmented epithelial cells, ARPE-19. A significant increase in LC3-II protein was observed when BL was irradiated on ARPE-19 cells containing A2E. The mammalian target of rapamycin (mTOR) pathway was examined to verify whether autophagy was activated, but no change in AKT, mTOR, and 4EBP phosphorylation was observed. Transcription factor EB (TFEB) target gene expression, which is another pathway involved in autophagy, was also not altered by A2E and BL. However, intracellular p62 protein levels were significantly increased, which represented the inhibition of autophagic flux. To investigate the mechanism of the suppressed autophagic flux, the lysosomal state was observed. After BL irradiation, lysosomal damage was induced in A2E-treated ARPE-19 cells, and this phenomenon was prevented by treatment with the antioxidant, N-acetylcysteine. Our results suggest that A2E photoactivation compromises autophagy in ARPE-19 cells and that reactive oxygen species (ROS) play an important role in this process., (Copyright © 2019 Elsevier Ltd. All rights reserved.)
- Published
- 2019
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40. Amelioration of muscle wasting by glucagon-like peptide-1 receptor agonist in muscle atrophy.
- Author
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Hong Y, Lee JH, Jeong KW, Choi CS, and Jun HS
- Subjects
- Animals, Disease Models, Animal, Humans, Male, Mice, Transfection, Glucagon-Like Peptide-1 Receptor therapeutic use, Muscular Atrophy drug therapy, Sarcopenia drug therapy
- Abstract
Background: Skeletal muscle atrophy is defined as a reduction of muscle mass caused by excessive protein degradation. However, the development of therapeutic interventions is still in an early stage. Although glucagon-like peptide-1 receptor (GLP-1R) agonists, such as exendin-4 (Ex-4) and dulaglutide, are widely used for the treatment of diabetes, their effects on muscle pathology are unknown. In this study, we investigated the therapeutic potential of GLP-1R agonist for muscle wasting and the mechanisms involved., Methods: Mouse C2C12 myotubes were used to evaluate the in vitro effects of Ex-4 in the presence or absence of dexamethasone (Dex) on the regulation of the expression of muscle atrophic factors and the underlying mechanisms using various pharmacological inhibitors. In addition, we investigated the in vivo therapeutic effect of Ex-4 in a Dex-induced mouse muscle atrophy model (20 mg/kg/day i.p.) followed by injection of Ex-4 (100 ng/day i.p.) for 12 days and chronic kidney disease (CKD)-induced muscle atrophy model. Furthermore, we evaluated the effect of a long-acting GLP-1R agonist by treatment of dulaglutide (1 mg/kg/week s.c.) for 3 weeks, in DBA/2J-mdx mice, a Duchenne muscular dystrophy model., Results: Ex-4 suppressed the expression of myostatin (MSTN) and muscle atrophic factors such as F-box only protein 32 (atrogin-1) and muscle RING-finger protein-1 (MuRF-1) in Dex-treated C2C12 myotubes. The suppression effect was via protein kinase A and protein kinase B signalling pathways through GLP-1R. In addition, Ex-4 treatment inhibited glucocorticoid receptor (GR) translocation by up-regulating the proteins of GR inhibitory complexes. In a Dex-induced muscle atrophy model, Ex-4 ameliorated muscle atrophy by suppressing muscle atrophic factors and enhancing myogenic factors (MyoG and MyoD), leading to increased muscle mass and function. In the CKD muscle atrophy model, Ex-4 also increased muscle mass, myofiber size, and muscle function. In addition, treatment with a long-acting GLP-1R agonist, dulaglutide, recovered muscle mass and function in DBA/2J-mdx mice., Conclusions: GLP-1R agonists ameliorate muscle wasting by suppressing MSTN and muscle atrophic factors and enhancing myogenic factors through GLP-1R-mediated signalling pathways. These novel findings suggest that activating GLP-1R signalling may be useful for the treatment of atrophy-related muscular diseases., (© 2019 The Authors Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of Society on Sarcopenia, Cachexia and Wasting Disorders.)
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- 2019
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41. Influence of surface treatments and repair materials on the shear bond strength of CAD/CAM provisional restorations.
- Author
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Jeong KW and Kim SH
- Abstract
Purpose: To evaluate the effect of surface treatments and repair materials on the shear bond strength and to measure the fracture toughness of CAD/CAM provisional restoration materials., Materials and Methods: Four CAD/CAM (3D printing: Nextdent C&B and ZMD-1000B Temporary, CAD/CAM resin block: Yamahachi PMMA disk and Huge PMMA block) and four conventional (monometacrylate: Jet and Alike, dimetacrylate: Luxatemp and Protemp 4) materials were selected to fabricate disk-shaped specimens and divided into six groups according to surface treatment (n=10). CAD/CAM materials were repaired with Jet or Luxatemp, while conventional materials were repaired with their own materials. The shear bond strength was measured by using universal testing machine. Ten rectangular column-shaped specimens for each material were fabricated to measure the fracture toughness by single edge v notched beam technique. Statistical analysis was performed by one-way ANOVA., Results: The highest shear bond strength of CAD/CAM materials was achieved by SiC paper + sandblasting. It was also accomplished when repairing 3D printing materials with Luxatemp, and repairing CAD/CAM resin blocks with Jet. Yamahachi PMMA disk showed the highest fracture toughness. Nextdent C&B showed the lowest fracture toughness value but no statistically significant difference from Alike and Luxatemp ( P >.05)., Conclusion: In order to successfully repair the CAD/CAM provisional restoration, mechanical surface treatment and appropriate repair material according to the CAD/CAM material type should be selected. The CAD/CAM provisional materials have proper mechanical properties for clinical use as compared to conventional materials.
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- 2019
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42. Isolation of MLL1 Inhibitory RNA Aptamers.
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Ul-Haq A, Jin ML, Jeong KW, Kim HM, and Chun KH
- Abstract
Mixed lineage leukemia proteins (MLL) are the key histone lysine methyltransferases that regulate expression of diverse genes. Aberrant activation of MLL promotes leukemia as well as solid tumors in humans, highlighting the urgent need for the development of an MLL inhibitor. We screened and isolated MLL1-binding ssRNAs using SELEX ( S ystemic E volution of L igands by Ex ponential enrichment) technology. When sequences in sub-libraries were obtained using next-generation sequencing (NGS), the most enriched aptamers-APT1 and APT2-represented about 30% and 26% of sub-library populations, respectively. Motif analysis of the top 50 sequences provided a highly conserved sequence: 5΄-A[A/C][C/G][G/U][U/A]ACAGAGGG[U/A]GG[A/C] GAGUGGGU-3΄. APT1, APT2, and APT5 embracing this motif generated secondary structures with similar topological characteristics. We found that APT1 and APT2 have a good binding activity and the analysis using mutated aptamer variants showed that the site information in the central region was critical for binding. In vitro enzyme activity assay showed that APT1 and APT2 had MLL1 inhibitory activity. Three-dimensional structure prediction of APT1-MLL1 complex indicates multiple weak interactions formed between MLL1 SET domain and APT1. Our study confirmed that NGS-assisted SELEX is an efficient tool for aptamer screening and that aptamers could be useful in diagnosis and treatment of MLL1-mediated diseases.
- Published
- 2019
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43. Flightless-I mediates the repression of estrogen receptor α target gene expression by the glucocorticoid receptor in MCF-7 cells.
- Author
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Yang L and Jeong KW
- Subjects
- Breast Neoplasms metabolism, Dexamethasone pharmacology, Estradiol pharmacology, Estrogen Receptor alpha drug effects, Estrogen Receptor alpha metabolism, Estrogens pharmacology, Glucocorticoids pharmacology, Humans, MCF-7 Cells, Microfilament Proteins drug effects, Microfilament Proteins metabolism, Receptors, Cytoplasmic and Nuclear drug effects, Receptors, Cytoplasmic and Nuclear metabolism, Receptors, Glucocorticoid drug effects, Receptors, Glucocorticoid metabolism, Response Elements, Trans-Activators, Breast Neoplasms genetics, Estrogen Receptor alpha genetics, Gene Expression Regulation, Neoplastic, Microfilament Proteins genetics, Receptors, Cytoplasmic and Nuclear genetics, Receptors, Glucocorticoid genetics
- Abstract
The human homologue of flightless-I (FLII) belong to the gelsolin protein family and contain a gelsolin-like domain at the C-terminus and a leucine-rich repeat (LRR) domain at the N-terminus. FLII regulates estrogen receptor alpha (ERα) and glucocorticoid receptor (GR)-mediated transcription by direct interaction through different domains, suggestive of its potential role in the crosstalk between the ERα and GR signaling pathway. Here, we demonstrate that FLII plays a critical role in GR-mediated repression of ERα target gene expression. In FLII-depleted cells, the reduction in 17-β-estradiol (E2)-induced ERα occupancy following treatment with dexamethasone (Dex) at the estrogen responsive element (ERE) site of the ERα target gene was significantly inhibited. The ERE binding of GR by the cotreatment with E2 and Dex was significantly inhibited by FLII depletion, indicating that FLII is required for the recruitment of GR at the ERE sites of ERα target genes. In addition, the recruitment of ERα-induced FLII to ERE sites was significantly reduced by Dex treatment. In protein binding assays, GR inhibited the E2-induced interaction between ERα and FLII, suggesting that GR interferes with the binding of ERα and FLII at the ERα target genes, resulting in the release of ERα and FLII from EREs. Taken together, our data reveal an unknown mechanism by which the transcription coactivator FLII regulates the GR-mediated repression of ERα target gene expression in MCF-7 cells.
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- 2019
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44. Avocado Oil Extract Modulates Auditory Hair Cell Function through the Regulation of Amino Acid Biosynthesis Genes.
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Nam YH, Rodriguez I, Jeong SY, Pham TNM, Nuankaew W, Kim YH, Castañeda R, Jeong SY, Park MS, Lee KW, Lee JS, Kim DH, Park YH, Kim SH, Moon IS, Choung SY, Hong BN, Jeong KW, and Kang TH
- Subjects
- Animals, Auditory Perception drug effects, Cochlea cytology, Cochlea drug effects, Cochlea metabolism, Hair Cells, Auditory metabolism, Hair Cells, Auditory physiology, Hearing Loss, Noise-Induced drug therapy, Hearing Loss, Noise-Induced genetics, Hearing Loss, Noise-Induced metabolism, Hearing Loss, Noise-Induced physiopathology, Metabolic Networks and Pathways drug effects, Metabolic Networks and Pathways genetics, Mice, Plant Extracts pharmacology, Plant Extracts therapeutic use, Plant Oils therapeutic use, Sequence Analysis, RNA, Zebrafish, Amino Acids biosynthesis, Gene Expression Regulation drug effects, Hair Cells, Auditory drug effects, Hearing Loss, Sensorineural drug therapy, Hearing Loss, Sensorineural genetics, Hearing Loss, Sensorineural metabolism, Hearing Loss, Sensorineural physiopathology, Persea chemistry, Phytotherapy, Plant Oils pharmacology
- Abstract
Sensorineural hearing loss (SNHL) is one of the most common causes of disability, affecting over 466 million people worldwide. However, prevention or therapy of SNHL has not been widely studied. Avocado oil has shown many health benefits but it has not yet been studied in regards to SNHL. Therefore, we aimed to investigate the efficacy of avocado oil on SNHL in vitro and in vivo and elucidate its mode of action. For the present study, we used enhanced functional avocado oil extract (DKB122). DKB122 led to recovery of otic hair cells in zebrafish after neomycin-induced otic cell damage. Also, DKB122 improved auditory sensory transmission function in a mouse model of noise induced-hearing loss and protected sensory hair cells in the cochlea. In addition, RNA sequencing was performed to elucidate the mechanism involved. KEGG pathway enrichment analysis of differentially expressed genes showed that DKB122 protected House Ear Institute-Organ of Corti 1 (HEI-OC1) cells against neomycin-related alterations in gene expression due to oxidative stress, cytokine production and protein synthesis.
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- 2019
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45. Aberrant expression of SETD1A promotes survival and migration of estrogen receptor α-positive breast cancer cells.
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Jin ML, Kim YW, Jin HL, Kang H, Lee EK, Stallcup MR, and Jeong KW
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- Apoptosis drug effects, Apoptosis genetics, Breast Neoplasms drug therapy, Cell Cycle drug effects, Cell Cycle genetics, Cell Line, Tumor, Cell Movement drug effects, Cell Proliferation drug effects, Cell Proliferation genetics, Cell Survival drug effects, Cell Survival genetics, Down-Regulation drug effects, Down-Regulation genetics, Drug Resistance, Neoplasm drug effects, Drug Resistance, Neoplasm genetics, Female, Gene Expression Regulation, Neoplastic drug effects, Humans, MCF-7 Cells, MicroRNAs genetics, Tamoxifen pharmacology, Up-Regulation drug effects, Up-Regulation genetics, Breast Neoplasms genetics, Cell Movement genetics, Estrogen Receptor alpha genetics, Gene Expression Regulation, Neoplastic genetics, Histone-Lysine N-Methyltransferase genetics
- Abstract
The histone H3 lysine 4-specific methyltransferase SETD1A is associated with transcription activation and is considered a key epigenetic regulator that modulates the cell cycle and metastasis in triple-negative breast cancer cells. However, the clinical role of SETD1A in estrogen receptor (ER)-positive breast cancer cells remains unclear. Here, we examined whether SETD1A is a potential target for ERα-positive breast cancer therapy. SETD1A expression was upregulated in breast tumor tissue compared to that in normal breast tissue. Moreover, ER-target genes regulated by SETD1A were particularly enriched in cell cycle and cancer pathways. SETD1A is involved in histone H3K4 methylation, subsequent recruitment of ERα, and the establishment of accessible chromatin structure at the enhancer region of ERα target genes. In addition to ERα target genes, other cell survival genes were also downregulated by SETD1A depletion in MCF-7 cells, leading to significant decrease in cell proliferation and migration, and spontaneous induction of apoptosis. We also found that miR-1915-3p functioned as a novel regulator of SETD1A expression in breast cells. Importantly, the growth of tamoxifen-resistant MCF-7 cells was effectively repressed by SETD1A knockdown. These results indicate that SETD1A may serve as a molecular target and prognostic indicator in ERα-positive breast cancer., (© 2018 UICC.)
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- 2018
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46. BAF53A regulates androgen receptor-mediated gene expression and proliferation in LNCaP cells.
- Author
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Jin ML, Kim YW, and Jeong KW
- Subjects
- Actins metabolism, Cell Line, Tumor, Cell Proliferation, Chromosomal Proteins, Non-Histone metabolism, DNA-Binding Proteins metabolism, Humans, Male, Prostatic Neoplasms metabolism, Prostatic Neoplasms pathology, Transcriptional Activation, Actins physiology, Chromosomal Proteins, Non-Histone physiology, DNA-Binding Proteins physiology, Gene Expression Regulation, Neoplastic, Prostatic Neoplasms genetics, Receptors, Androgen metabolism
- Abstract
The actin-like protein of the SWI/SNF complex, BAF53A, regulates gene expression by the gene-specific chromatin remodeling of target genes. However, the function of BAF53A in the androgen receptor pathway in prostate cancer cells remains unclear. Here, we demonstrated that BAF53A positively regulates the expression of endogenous AR target genes (e.g. PSA, TMPRSS2, FKBP5, and KLK2) in LNCaP cells. It functions as a coactivator in AR-mediated transcription by interacting with other nuclear receptor coactivators, such as p300 and FLII, and is associated with AR in the presence of dihydrotestosterone (DHT). The DHT-induced recruitment of BAF53A to the proximal and distal androgen response elements (AREs) of the PSA gene in the presence of BRG1 (but not BRM) was inhibited by an AR antagonist, suggesting the coactivator function of BAF53A in the SWI/SNF complex. Depletion of BAF53A in LNCaP cells resulted in a significant decrease in growth rate. Furthermore, the expression of BAF53A in prostate cancer tissue was significantly elevated, compared to that in normal prostate tissue, and correlated with the expression of AR, and BRG1, but not BRM. Therefore, our results suggested that BAF53A plays an important role in the expression of AR target genes in prostate cancer, and can be used clinically for the treatment of prostate cancer., (Copyright © 2018 Elsevier Inc. All rights reserved.)
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- 2018
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47. Tyr51: Key Determinant of the Low Thermostability of the Colwellia psychrerythraea Cold-Shock Protein.
- Author
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Lee Y, Kwak C, Jeong KW, Durai P, Ryu KS, Kim EH, Cheong C, Ahn HC, Kim HJ, and Kim Y
- Subjects
- Alteromonadaceae metabolism, Amino Acid Sequence, Bacterial Proteins metabolism, Cold Shock Proteins and Peptides metabolism, Hot Temperature, Hydrophobic and Hydrophilic Interactions, Molecular Docking Simulation, Molecular Dynamics Simulation, Protein Binding, Protein Conformation, Protein Folding, Protein Stability, Sequence Alignment, Thymidine analogs & derivatives, Thymidine metabolism, Tyrosine chemistry, Tyrosine metabolism, Alteromonadaceae chemistry, Bacterial Proteins chemistry, Cold Shock Proteins and Peptides chemistry
- Abstract
Cold-shock proteins (Csps) are expressed at lower-than-optimum temperatures, and they function as RNA chaperones; however, no structural studies on psychrophilic Csps have been reported. Here, we aimed to investigate the structure and dynamics of the Csp of psychrophile Colwellia psychrerythraea 34H, ( Cp-Csp). Although Cp-Csp shares sequence homology, common folding patterns, and motifs, including a five β-stranded barrel, with its thermophilic counterparts, its thermostability (37 °C) was markedly lower than those of other Csps. Cp-Csp binds heptathymidine with an affinity of 10
-7 M, thereby increasing its thermostability to 50 °C. Nuclear magnetic resonance spectroscopic analysis of the Cp-Csp structure and backbone dynamics revealed a flexible structure with only one salt bridge and 10 residues in the hydrophobic cavity. Notably, Cp-Csp contains Tyr51 instead of the conserved Phe in the hydrophobic core, and its phenolic hydroxyl group projects toward the surface. The Y51F mutation increased the stability of hydrophobic packing and may have allowed for the formation of a K3-E21 salt bridge, thereby increasing its thermostability to 43 °C. Cp-Csp exhibited conformational exchanges in its ribonucleoprotein motifs 1 and 2 (754 and 642 s-1 ), and heptathymidine binding markedly decreased these motions. Cp-Csp lacks salt bridges and has longer flexible loops and a less compact hydrophobic cavity resulting from Tyr51 compared to mesophilic and thermophilic Csps. These might explain the low thermostability of Cp-Csp. The conformational flexibility of Cp-Csp facilitates its accommodation of nucleic acids at low temperatures in polar oceans and its function as an RNA chaperone for cold adaptation.- Published
- 2018
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48. Quercetin-3-O-α-l-arabinopyranoside protects against retinal cell death via blue light-induced damage in human RPE cells and Balb-c mice.
- Author
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Kim J, Jin HL, Jang DS, Jeong KW, and Choung SY
- Subjects
- Absorption, Physiological radiation effects, Animals, Anti-Inflammatory Agents, Non-Steroidal administration & dosage, Anti-Inflammatory Agents, Non-Steroidal metabolism, Anti-Inflammatory Agents, Non-Steroidal therapeutic use, Cell Line, Cell Line, Tumor, Cell Survival radiation effects, Gene Expression Regulation radiation effects, Genes, Reporter radiation effects, Humans, Macular Degeneration etiology, Macular Degeneration metabolism, Macular Degeneration pathology, Male, Mice, Inbred BALB C, Microscopy, Fluorescence, Oxidation-Reduction, Quercetin administration & dosage, Quercetin metabolism, Quercetin therapeutic use, Radiation-Protective Agents administration & dosage, Radiation-Protective Agents metabolism, Random Allocation, Retinal Pigment Epithelium immunology, Retinal Pigment Epithelium pathology, Retinal Pigment Epithelium radiation effects, Retinoids metabolism, Retinoids radiation effects, Apoptosis radiation effects, Dietary Supplements, Light adverse effects, Macular Degeneration prevention & control, Quercetin analogs & derivatives, Radiation-Protective Agents therapeutic use, Retinal Pigment Epithelium metabolism
- Abstract
Age-related macular degeneration (AMD) is among the increasing number of diseases causing irreversible blindness in the elderly. Dry AMD is characterized by the accumulation of lipofuscin in retinal pigment epithelium (RPE) cells. N-Retinylidene-N-retinylethanolamine (A2E), a component of lipofuscin, is oxidized to oxo-A2E under blue light illumination, leading to retinal cell death. The aim of this study was to investigate the protective effect and mechanism of quercetin-3-O-α-l-arabinopyranoside (QA) against blue light (BL)-induced damage in both RPE cells and mice models. Treatment by QA inhibited A2E uptake in RPE cells, as determined by a decrease in fluorescence intensity. QA also protected A2E-laden RPE cells against BL-induced apoptosis. QA inhibited C3 complement activation and poly (ADP-ribose) polymerase (PARP) cleavage, as determined by western blotting. QA showed an inhibitory effect on AP1 and NF-kB activity as estimated in a reporter gene assay. In addition, QA activated the gene expression of aryl hydrocarbon receptor target genes (CYP1A1, CYP1B1) in TCDD-treated RPE cells. In the mice model, oral administration of QA protected against retinal degeneration induced by BL exposure as determined by histological analyses (thickness of retinal layers and immunostaining for caspase-3). In addition, QA inhibited apoptosis and inflammation via inhibition of NF-kB p65 translocation, C3 activation, and PARP cleavage. Collectively, these results revealed the protective mechanism of QA against BL-induced retinal damage both in vitro and in vivo.
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- 2018
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49. Finasteride inhibits melanogenesis through regulation of the adenylate cyclase in melanocytes and melanoma cells.
- Author
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Seo JO, Yumnam S, Jeong KW, and Kim SY
- Subjects
- Animals, Cell Line, Cell Survival drug effects, Cell Survival physiology, Dose-Response Relationship, Drug, Melanoma, Experimental drug therapy, Mice, Receptor, Melanocortin, Type 1 antagonists & inhibitors, Receptor, Melanocortin, Type 1 metabolism, Adenylyl Cyclases physiology, Finasteride pharmacology, Melanocytes drug effects, Melanocytes enzymology, Melanoma, Experimental enzymology
- Abstract
Finasteride is a well-known 5α-reductase inhibitor used for treatment of alopecia and prostate cancer. But the effect of finasteride in regulating melanogenesis is still unclear. In the present study the role of finasteride on melanogenesis was investigated. Finasteride decrease melanin level in melanocyte melan-a cells and B16F10 melanoma cells without inducing cytotoxicity. MC1R (melanocortin 1 receptor) protein expression was also inhibited by finasteride thereby decreasing the expression of adenylate cyclase, MITF (Melanogenesis associated transcription factor), tyrosinases, TRP (tyrosinase-related protein) -1 and -2. Thus our study suggest that finasteride inhibits melanogenesis in melanocyte and melanoma cells by inhibiting MC1R.
- Published
- 2018
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50. Efficacy and Safety of Fully Covered Self-Expanding Metal Stents for Malignant Esophageal Obstruction.
- Author
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So H, Ahn JY, Han S, Jung K, Na HK, Lee JH, Jeong KW, Kim DH, Choi KD, Song HJ, Lee GH, and Jung HY
- Subjects
- Aged, Female, Humans, Male, Palliative Care methods, Prosthesis Failure, Retrospective Studies, Treatment Outcome, Esophageal Neoplasms complications, Esophageal Stenosis surgery, Self Expandable Metallic Stents adverse effects
- Abstract
Background: Malignant dysphagia can result in poor nutritional status with severe weight loss. Rapid relief from dysphagia can be achieved with esophageal self-expanding metal stents (SEMSs), a minimally invasive method. In this study, we evaluated the usefulness of SEMSs for malignant dysphagia., Methods: Between 2012 and 2015, 119 patients with malignant dysphagia underwent esophageal SEMS insertion with endoscopic assistance. Their demographics and clinical outcomes were collected. Factors associated with stent-related complications and patient survival were evaluated. All data were retrospectively analyzed., Results: The mean age of the 119 patients was 64.9 ± 11.6 years, and 25 (21%) were female. Seventy-five patients (63.0%) had squamous carcinoma, majority of which were located in the lower thoracic esophagus (n = 42), followed by middle thoracic esophagus (n = 19) and upper esophagus (n = 10). Eighty patients (67.2%) underwent SEMS insertion at diagnosis. Technical and clinical success rates were 99.2 and 89.9%, respectively. Complications occurred in 47 patients (39.5%); the most common complication was migration (36.3%), followed by pain and obstruction. The median stent patency time was 145 days (95% confidence interval 55.19-234.81 days). Gastric cancer (odds ratio 3.51, 95% confidence interval 1.21-10.15; p = 0.021) and a 20-mm-wide stent (odds ratio 2.922, 95% confidence interval 1.237-6.904; p = 0.015) were risk factors for complications., Conclusions: SEMSs are effective in palliation of malignant dysphagia. However, stent-related complications should be borne in mind, particularly in patients with gastric cancer with esophageal invasion and with larger width stents.
- Published
- 2018
- Full Text
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