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Search Results: 1 - 10 of 8234 matches for " Jung-Hee Yoon "
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An Inflammatory Fibroid Polyp (Vanek’s Tumor) of the Ileum that Presented as Intussusception  [PDF]
Jung-Hee Yoon
Advances in Computed Tomography (ACT) , 2013, DOI: 10.4236/act.2013.24024

Ileoileal intussusceptions caused by inflammatory fibroid polyps are uncommon. Inflammatory fibroid polyps (Vanek’s tumor) are rare benign lesions that originate in the submucosa of the gastrointestinal tract. Here, we report the case of a 54-year-old woman who was admitted with an acute onset of abdominal pain and signs of intestinal obstruction. The ileal segment was resected, and single-layer end-to-end anastomosis was performed. A submucosal polypoid mass measuring approximately 4.5 × 4.0 cm was found. The histopathological analysis revealed an ulcerated mucosal lesion with variable cellularity that was formed by spindle cells with slight mitosis and abundant inflammatory infiltrate that was mainly composed of eosinophils. Immunohistochemistry confirmed the diagnosis of ileal inflammatory fibroid polyps. Cross-sectional imaging (multidetector computed tomography) plays a significant role in diagnosing this condition and guiding its management.

A Retroperitoneal Inflammatory Myofibroblastic Tumor Mimicking a Germ Cell Tumor of the Undescended Testis: A Case Report and Literature Review  [PDF]
Seul-Bi Lee, Jung-Hee Yoon, Seung-Ho Kim, Yedaun Lee, Jin-Soo Lee, Jung-Wook Seo
Advances in Computed Tomography (ACT) , 2016, DOI: 10.4236/act.2016.53004
Abstract: We report here a case of an inflammatory myofibroblastic tumor in the retroperitoneum, which mimicked a germ cell tumor of the undescended testis. A 75-year-old healthy man presented with a palpable abdominal mass. On the computed tomography image, there was large, well-defined soft tissue mass in the left side of the retroperitoneum, and there was no visible left testis or seminal vesicle. After contrast enhancement, the mass appeared to be relatively homogeneous, considering its large size. With ultrasonography, it appeared as a well-defined, hypoechoic mass with intratumoral vascularity. This solid mass was surgically diagnosed as an inflammatory myofibroblastic tumor.
MicroRNA-27a Modulates HCV Infection in Differentiated Hepatocyte-Like Cells from Adipose Tissue-Derived Mesenchymal Stem Cells
Jung Eun Choi, Wonhee Hur, Jung-Hee Kim, Tian Zhu Li, Eun Byul Lee, Sung Won Lee, Wonseok Kang, Eui-Cheol Shin, Takaji Wakita, Seung Kew Yoon
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091958
Abstract: Background and Aims Despite the discovery of hepatitis C virus (HCV) entry factor, the mechanism by which it is regulated by miRNAs remains unclear. Adipose tissue-derived human mesenchymal stem cells (AT-hMSCs) have been widely used for differentiated hepatocyte-like cells (DHCs). Here, we established an in vitro HCV infection model using DHCs from AT-hMSCs and identified miRNAs that modulate HCV infectivity. Methods AT-hMSCs were differentiated into DHCs using the conditional media, and evaluated for hepatocyte characteristics using RT-PCR, immunocytochemistry, periodic acid-Schiff staining, and a urea synthesis assay. The expression of HCV candidate receptors was also verified using immunocytochemistry. The levels of candidate miRNAs targeting HCV receptors were then determined by relative quantitative RT-PCR (rqRT-PCR). Finally, DHCs were infected using HCVcc and serum from HCV-infected patients, and infectivity of the virus was measured by rqRT-PCR and transmission electron microscopy (TEM). Results The expected changes in morphology, function and hepatic gene expression were observed during hepatic differentiation. Moreover, the expression of candidate HCV entry factors and miR-27a were altered during hepatic differentiation. The infection and replication of HCV occurred efficiently in DHCs treated with HCVcc or infected with serum from HCV-infected patients. In addition, HCV infectivity was suppressed in miR-27a-transfected DHCs, due to the inhibition of LDLR expression by miR-27a. Conclusions Our results demonstrate that AT-hMSCs are a good source of DHCs, which are suitable for in vitro cultivation of HCV. Furthermore, these results suggest that miR-27a modulates HCV infectivity by regulating LDLR expression.
Enhancement in Light Extraction Efficiency of GaN-Based Light-Emitting Diodes Using Double Dielectric Surface Passivation  [PDF]
Chung-Mo Yang, Dong-Seok Kim, Yun Soo Park, Jae-Hoon Lee, Yong Soo Lee, Jung-Hee Lee
Optics and Photonics Journal (OPJ) , 2012, DOI: 10.4236/opj.2012.23028
Abstract: SiO2Al2O3 double dielectric stack layer was deposited on the surface of the GaN-based light-emitting diode (LED). The double dielectric stack layer enhances both the electrical characteristics and the optical output power of the LED because the first Al2O3 layer plays a role of effectively passivating the p-GaN surface and the second lower index SiO2 layer increases the critical angle of the light emitted from the LED surface. In addition, the effect of the Fresnel reflection is also responsible for the enhancement in output power of the double dielectric passivated LED. The leakage current of the LED passivated with Al2O3 layer was -3.46 × 10-11 A at -5 V, at least two and three orders lower in magnitude compared to that passivated with SiO2 layer (-7.14 × 10-9 A) and that of non-passivated LED (-1.9 × 10-8 A), respectively, which indicates that the Al2O3 layer is very effective in passivating the exposed GaN surface after dry etch and hence reduces nonradiative recombination as well as reabsorption of the emitted light near the etched surface.
Epigenetic mechanisms involved in differential MDR1 mRNA expression between gastric and colon cancer cell lines and rationales for clinical chemotherapy
Tae-Bum Lee, Jung-Hee Park, Young-Don Min, Kyung-Jong Kim, Cheol-Hee Choi
BMC Gastroenterology , 2008, DOI: 10.1186/1471-230x-8-33
Abstract: The MDR1 mRNA levels were determined using PCR and real-time PCR assays after reverse transcription. Cytotoxicity was performed using the MTT assay. Methylation status was explored by quantification PCR-based methylation and bisulfite DNA sequencing analyses.The MDR1 mRNA levels obtained by 35 cycles of RT-PCR in gastric cancer cells were just comparable to those obtained by 22 cycles of RT-PCR in colon cancer cells. Real-time RT-PCR analysis revealed that MDR1 mRNA was not detected in the 10 gastric cancer cell lines but variable MDR1 mRNA levels in 7 of 9 colon cancer cell lines except the SNU-C5 and HT-29 cells. MTT assay showed that Pgp inhibitors such as cyclosporine A, verapamil and PSC833 sensitized Colo320HSR (colon, highest MDR1 expression) but not SNU-668 (gastric, highest) and SNU-C5 (gastric, no expression) to paclitaxel. Quantification PCR-based methylation analysis revealed that 90% of gastric cancer cells, and 33% of colon cancer cells were methylated, which were completely matched with the results obtained by bisulfite DNA sequencing analysis. 5-aza-2'-deoxcytidine (5AC, a DNA methyltransferase inhibitor) increased the MDR1 mRNA levels in 60% of gastric cells, and in 11% of colon cancer cells. Trichostatin A (TSA, histone deacetylase inhibitor) increased the MDR1 mRNA levels in 70% of gastric cancer cells and 55% of colon cancer cells. The combined treatment of 5AC with TSA increased the MDR1 mRNA levels additively in 20% of gastric cancer cells, but synergistically in 40% of gastric and 11% of colon cancer cells.These results indicate that the MDR1 mRNA levels in gastric cancer cells are significantly lower than those in colon cancer cells, which is at least in part due to different epigenetic regulations such as DNA methylation and/or histone deacetylation. These results can provide a better understanding of the efficacy of combined chemotherapy as well as their oral bioavailability.Gastric and colorectal cancers are a cause of morbidity and mortal
Modeling of subthreshold characteristics for undoped and doped deep nanoscale short channel double-gate MOSFETs
Analytical Modeling of Subthreshold Characteristics for Undoped and Doped Deep Nanoscale Short Channel Double-Gate MOSFETs

Jin Xiaoshi,Liu Xi,Wu Meile,Chuai Rongyan,Jung-Hee Lee,Jong-Ho Lee,
,刘溪,吴美乐,揣荣岩,Jung-Hee Lee,Jong-Ho Lee

半导体学报 , 2012,
Abstract: A model of subthreshold characteristics for both undoped and doped double-gate (DG) MOSFETs has been proposed. The models were developed based on solution of 2-D Poisson's equation using variable separation technique. Without any fitting parameters, our proposed models can exactly reflect the degraded subthreshold characteristics due to nanoscale channel length. Also, design parameters such as body thickness, gate oxide thickness and body doping concentrations can be directly reflected from our models. The models have been verified by comparing with device simulations' results and found very good agreement.
Biochemical characterization of a recombinant Japanese encephalitis virus RNA-dependent RNA polymerase
Yeon-Gu Kim, Ji-Seung Yoo, Jung-Hee Kim, Chan-Mi Kim, Jong-Won Oh
BMC Molecular Biology , 2007, DOI: 10.1186/1471-2199-8-59
Abstract: To characterize the biochemical properties of JEV RdRp, we expressed in Escherichia coli and purified an enzymatically active full-length recombinant JEV NS5 protein with a hexahistidine tag at the N-terminus. The purified NS5 protein, but not the mutant NS5 protein with an Ala substitution at the first Asp of the RdRp-conserved GDD motif, exhibited template- and primer-dependent RNA synthesis activity using a poly(A) RNA template. The NS5 protein was able to use both plus- and minus-strand 3'-untranslated regions of the JEV genome as templates in the absence of a primer, with the latter RNA being a better template. Analysis of the RNA synthesis initiation site using the 3'-end 83 nucleotides of the JEV genome as a minimal RNA template revealed that the NS5 protein specifically initiates RNA synthesis from an internal site, U81, at the two nucleotides upstream of the 3'-end of the template.As a first step toward the understanding of the molecular mechanisms for JEV RNA replication and ultimately for the in vitro reconstitution of viral RNA replicase complex, we for the first time established an in vitro JEV RdRp assay system with a functional full-length recombinant JEV NS5 protein and characterized the mechanisms of RNA synthesis from nonviral and viral RNA templates. The full-length recombinant JEV NS5 will be useful for the elucidation of the structure-function relationship of this enzyme and for the development of anti-JEV agents.Japanese encephalitis virus (JEV) is the most common cause of epidemic viral encephalitis worldwide, with approximately 50,000 cases and 15,000 deaths annually throughout a wide geographical range [1]. Since the prototype Nakayama strain of JEV was first isolated in 1935, epidemics and sporadic cases of Japanese encephalitis have occurred in temperate and tropical zones of Asia as well as in non-Asian regions, including Cambodia, China, Indonesia, India, Japan, Malaysia, Myanmar, Nepar, Sri Lanka, Thailand, Vietnam, the south eastern Ru
Effect of In Composition on Two-Dimensional Electron Gas in Wurtzite AlGaN/InGaN Heterostructures

KIM Bong-Hwan,PARK Seoung-Hwan,LEE Jung-Hee,MOON Yong-Tae,

中国物理快报 , 2010,
Magneto-gyrotropic photogalvanic effects in GaN/AlGaN two-dimensional systems
W. Weber,S. Seidl,S. N. Danilov,W. Prettl,V. V. Bel'kov,L. E. Golub,E. L. Ivchenko,Z. D. Kvon,Hyun-Ick Cho,Jung-Hee Lee,S. D. Ganichev
Physics , 2007, DOI: 10.1016/j.ssc.2007.09.035
Abstract: The magneto-gyrotropic photogalvanic and spin-galvanic effects are observed in (0001)-oriented GaN/AlGaN heterojunctions excited by terahertz radiation. We show that free-carrier absorption of linearly or circularly polarized terahertz radiation in low-dimensional structures causes an electric photocurrent in the presence of an in-plane magnetic field. Microscopic mechanisms of these photocurrents based on spin-related phenomena are discussed. Properties of the magneto-gyrotropic and spin-galvanic effects specific for hexagonal heterostructures are analyzed.
Demonstration of Rashba spin splitting in GaN-based heterostructures
W. Weber,S. D. Ganichev,Z. D. Kvon,V. V. Bel'kov,L. E. Golub,S. N. Danilov,D. Weiss,W. Prettl,Hyun-Ick Cho,Jung-Hee Lee
Physics , 2005, DOI: 10.1063/1.2158024
Abstract: The circular photogalvanic effect (CPGE), induced by infrared radiation, has been observed in (0001)-oriented GaN quantum well (QW) structures. The photocurrent changes sign upon reversing the radiation helicity demonstrating the existence of spin-splitting of the conduction band in k-space in this type of materials. The observation suggests the presence of a sizeable Rashba type of spin-splitting, caused by the built-in asymmetry at the AlGaN/GaN interface.
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