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Search Results: 1 - 10 of 21223 matches for " Seok-Hyung Kim "
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The Prognostic Significance of Cancer-Associated Fibroblasts in Esophageal Squamous Cell Carcinoma
Sang Yun Ha, So-Young Yeo, Yan-hiua Xuan, Seok-Hyung Kim
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0099955
Abstract: Background Cancer-associated fibroblasts (CAF) are activated fibroblasts in the cancer stroma and play an important role in cancer progression. Some reports have indicated the correlation between the expression of CAF markers and adverse prognosis in several cancers. However, no reports have studied CAF phenotype and its clinical relevance in esophageal squamous cell carcinoma (ESCC). Methods We investigated CAF phenotype of ESCC based on histology and immunohistochemical expressions of five CAF markers such as fibroblast activation protein (FAP), smooth muscle actin (SMA), fibroblast-specific protein-1 (FSP1), platelet-derived growth factor receptor (PDGFRα), and PDGFRβ in 116 ESCC tissue samples. Besides, we also examined the correlation of the CAF phenotype with clinical relevance as well as other cancer-microenvironment related factors. Results Histologically immature CAF phenotype was correlated with poor prognosis (p<0.001) and associated with increased microvessel density, increased tumor associated macrophages, and epithelial to mesenchymal transition. CAF markers were characteristically expressed in stromal fibroblast close to tumor cells and the expression pattern of 5 CAF markers was highly heterogeneous in every individual cases. Of five CAF markers, SMA, FSP1, and PDGFRα were unfavorable prognostic indicators of ESCC. The number of positive CAF markers was greater in ESCC with immature CAFs than in those with mature ones. Conclusions Our results demonstrate that histologic classification of CAF phenotype is a reliable and significant prognostic predictor in ESCC. CAF markers have the potential to be diagnostic and therapeutic targets in ESCC.
Multi-organ Abnormalities and mTORC1 Activation in Zebrafish Model of Multiple Acyl-CoA Dehydrogenase Deficiency
Seok-Hyung Kim ,Sarah A. Scott,Michael J. Bennett,Robert P. Carson,Joshua Fessel,H. Alex Brown,Kevin C. Ess
PLOS Genetics , 2013, DOI: 10.1371/journal.pgen.1003563
Abstract: Multiple Acyl-CoA Dehydrogenase Deficiency (MADD) is a severe mitochondrial disorder featuring multi-organ dysfunction. Mutations in either the ETFA, ETFB, and ETFDH genes can cause MADD but very little is known about disease specific mechanisms due to a paucity of animal models. We report a novel zebrafish mutant dark xavier (dxavu463) that has an inactivating mutation in the etfa gene. dxavu463 recapitulates numerous pathological and biochemical features seen in patients with MADD including brain, liver, and kidney disease. Similar to children with MADD, homozygote mutant dxavu463 zebrafish have a spectrum of phenotypes ranging from moderate to severe. Interestingly, excessive maternal feeding significantly exacerbated the phenotype. Homozygous mutant dxavu463 zebrafish have swollen and hyperplastic neural progenitor cells, hepatocytes and kidney tubule cells as well as elevations in triacylglycerol, cerebroside sulfate and cholesterol levels. Their mitochondria were also greatly enlarged, lacked normal cristae, and were dysfunctional. We also found increased signaling of the mechanistic target of rapamycin complex 1 (mTORC1) with enlarged cell size and proliferation. Treatment with rapamycin partially reversed these abnormalities. Our results indicate that etfa gene function is remarkably conserved in zebrafish as compared to humans with highly similar pathological, biochemical abnormalities to those reported in children with MADD. Altered mTORC1 signaling and maternal nutritional status may play critical roles in MADD disease progression and suggest novel treatment approaches that may ameliorate disease severity.
Low SP1 Expression Differentially Affects Intestinal-Type Compared with Diffuse-Type Gastric Adenocarcinoma
Hun Seok Lee, Cheol-Keun Park, Ensel Oh, ?zgür Cem Erkin, Hun Soon Jung, Mi-Hyun Cho, Mi Jeong Kwon, Seoung Wan Chae, Seok-Hyung Kim, Li-Hui Wang, Min-Jeong Park, Su-Yeon Lee, Ho Bin Yang, Lina Jia, Yoon-La Choi, Young Kee Shin
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0055522
Abstract: Specificity protein 1 (SP1) is an essential transcription factor that regulates multiple cancer-related genes. Because aberrant expression of SP1 is related to cancer development and progression, we focused on SP1 expression in gastric carcinoma and its correlation with disease outcomes. Although patient survival decreased as SP1 expression increased (P<0.05) in diffuse-type gastric cancer, the lack of SP1 expression in intestinal-type gastric cancer was significantly correlated with poor survival (P<0.05). The knockdown of SP1 in a high SP1-expressing intestinal-type gastric cell line, MKN28, increased migration and invasion but decreased proliferation. Microarray data in SP1 siRNA-transfected MKN28 revealed that the genes inhibiting migration were downregulated, whereas the genes negatively facilitating proliferation were increased. However, both migration and invasion were decreased by forced SP1 expression in a low SP1-expressing intestinal-type gastric cell line, AGS. Unlike the intestinal-type, in a high SP1-expressing diffuse-type gastric cell line, SNU484, migration and invasion were decreased by SP1 siRNA. In contrast to previous studies that did not identify differences between the 2 histological types, our results reveal that low expression of SP1 is involved in cancer progression and metastasis and differentially affects intestinal-type compared with diffuse-type gastric adenocarcinoma.
Autophagy Induction Is a Tor- and Tp53-Independent Cell Survival Response in a Zebrafish Model of Disrupted Ribosome Biogenesis
Yeliz Boglev,Andrew P. Badrock,Andrew J. Trotter,Qian Du,Elsbeth J. Richardson,Adam C. Parslow,Sebastian J. Markmiller,Nathan E. Hall,Tanya A. de Jong-Curtain,Annie Y. Ng,Heather Verkade,Elke A. Ober,Holly A. Field,Donghun Shin,Chong H. Shin,Katherine M. Hannan,Ross D. Hannan,Richard B. Pearson,Seok-Hyung Kim,Kevin C. Ess,Graham J. Lieschke,Didier Y. R. Stainier,Joan K. Heath
PLOS Genetics , 2013, DOI: 10.1371/journal.pgen.1003279
Abstract: Ribosome biogenesis underpins cell growth and division. Disruptions in ribosome biogenesis and translation initiation are deleterious to development and underlie a spectrum of diseases known collectively as ribosomopathies. Here, we describe a novel zebrafish mutant, titania (ttis450), which harbours a recessive lethal mutation in pwp2h, a gene encoding a protein component of the small subunit processome. The biochemical impacts of this lesion are decreased production of mature 18S rRNA molecules, activation of Tp53, and impaired ribosome biogenesis. In ttis450, the growth of the endodermal organs, eyes, brain, and craniofacial structures is severely arrested and autophagy is up-regulated, allowing intestinal epithelial cells to evade cell death. Inhibiting autophagy in ttis450 larvae markedly reduces their lifespan. Somewhat surprisingly, autophagy induction in ttis450 larvae is independent of the state of the Tor pathway and proceeds unabated in Tp53-mutant larvae. These data demonstrate that autophagy is a survival mechanism invoked in response to ribosomal stress. This response may be of relevance to therapeutic strategies aimed at killing cancer cells by targeting ribosome biogenesis. In certain contexts, these treatments may promote autophagy and contribute to cancer cells evading cell death.
Student User Satisfaction with Web-based Information Systems in Korean Universities
Hyung Seok Lee,Jae Won Kim
International Journal of Business and Management , 2009, DOI: 10.5539/ijbm.v5n1p62
Abstract: Despite of the rapid adoption of computer-based information systems in higher education in Korea and their increased importance both in education/research activities and administration, there have been few studies on whether these campus-wide information systems (CWIS) are being effectively used from the student user’ point of view. This study tests a modified model developed for this study based on previous literatures to measure student user satisfaction of the information systems. It was found that information and system satisfaction significantly affected the overall user satisfaction with CWIS.
The Estimation of Property Tax Capitalisation in the Korean Taxation Context  [PDF]
Hyung Min Kim, Kyoung-Seok Jang, Youn-Kyoung Hur
Current Urban Studies (CUS) , 2013, DOI: 10.4236/cus.2013.14012
Abstract: The difference between public services and property tax rates is capitalised into home values. The aim of this research is to estimate the property tax capitalisation rate under a different taxation context of Korea, using a repeat sales method with short-term data on housing prices and estimated tax payments. In the operation of the property taxation, there is complexity that needs to be considered in the estimation of the property tax capitalisation rate. In this research, 32,101 apartment samples in Seoul are used for the analysis. Given these unique institutional circumstances, as a result of the analysis, the property tax capitalisation rate in Seoul was between 73.7% and 82.8% in the analysis periods.
I3S: intelligent spectrum sensing scheme for cognitive radio networks
Waleed Ejaz, Najam ul Hasan, Seok Lee and Hyung Seok Kim
EURASIP Journal on Wireless Communications and Networking , 2013, DOI: 10.1186/1687-1499-2013-26
Abstract: Reliable spectrum sensing is one of the most crucial aspects for the successful deployment of cog- nitive radio (CR) technology. For CR, it is not possible to transmit on a licensed band and sense it simultaneously, therefore sensing must be interleaved with transmission. Spectrum sensing in CR is challenged by a number of uncertainties, which degrade the sensing performance and in turn require much more time to achieve the targeted sensing efficiency. Hence, the authors propose a spectrum sensing scheme which obtains reliable results with less mean detection time. First, the scheme deter- mines a better matched filter, or a combination of energy and cyclostationary detectors based on the power and band of interest. In the combined energy and cyclostationary detector, an energy detector with a bi-threshold is used, and the cyclostationary detector is applied only if the energy of the signal lies between two thresholds. Second, sensing is performed by the selection choice resulting from the first step. To evaluate the scheme's performance, the results are compared with those where only an energy detector, matched filter, or cyclostationary detector are performed. The performance metrics are the probability of detection, probability of false alarm, and mean detection time.
A Hybrid Structure of Dual Stators and a Pneumatic Spring for Resonance Control in an Air Mount  [PDF]
Hyung-Tae Kim, Cheol-Ho Kim, Sung-Bok Kang, Seok-Jun Moon, Gyu-Seop Lee
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2013, DOI: 10.4236/jemaa.2013.53019
Abstract:

An active device using electromagnetic forces was constructed and examined for the purpose of minimizing the resonance in air mounts of clean rooms. The air mounts are vulnerable to low-frequency resonance due to heavy weight and low stiffness. A hybrid structure of the active device, composed of pneumatic and electromagnetic parts, was developed and tested. The pneumatic parts in the device support heavy weights under the air mounts, and the electromagnetic parts reduce the resonance. The electromagnetic parts are composed of dual stators and an armature, which surround the pneumatic parts. The resonance can decrease when electromagnetic forces are generated in the gaps between the stators and the armature. Four active devices were installed under a 3-ton surface plate for a vibration test apparatus. The vibration was detected by eddy-current sensors. Discrete P Control logic was based on displacement, and embedded in a C6713 DSP. The results from impact tests show that the peak magnitude in the resonance frequency can be reduced to 10 dB.

Relationship between Synthesis Conditions and Photocatalytic Activity of Nanocrystalline TiO2
Yosep Han,Hyung-Seok Kim,Hyunjung Kim
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/427453
Abstract: The degradation efficiency of methylene blue by TiO2 nanoparticles, which were synthesized under different synthesis conditions (i.e., molar ratio of water and titanium tetraisopropoxide (TTIP), pH, and calcination temperature) in a sol-gel process, was systematically investigated. The results showed that increasing the molar ratio of water and TTIP led to the enhanced photocatalytic activity of TiO2 nanoparticles, which were likely attributed to the increased specific surface area of TiO2 nanoparticles synthesized with high molar ratio. The results were supported by the relative increase in the size of interaggregated pores of the aggregated TiO2 nanoparticles. The best photocatalytic activity of TiO2 nanoparticles was observed at acidic synthesis conditions; however, the results were not consistent with physical properties for the crystallinity and the crystallite size of TiO2 nanoparticles but rather explained by the presence of abundant hydroxyl groups and water molecules existing on the surface of TiO2 under acidic synthesis environments. Furthermore, methylene blue degradation experiments revealed that the photocatalytic activity of TiO2 nanoparticles was maximized at the calcination temperature of 700°C. The trend was likely due to the combined effect of the anatase crystallinity which showed the highest value at 700°C and the crystallite size/specific surface area which did not excessively increase up to 700°C.
Meat and Fish Freshness Inspection System Based on Odor Sensing
Najam ul Hasan,Naveed Ejaz,Waleed Ejaz,Hyung Seok Kim
Sensors , 2012, DOI: 10.3390/s121115542
Abstract: We propose a method for building a simple electronic nose based on commercially available sensors used to sniff in the market and identify spoiled/contaminated meat stocked for sale in butcher shops. Using a metal oxide semiconductor-based electronic nose, we measured the smell signature from two of the most common meat foods (beef and fish) stored at room temperature. Food samples were divided into two groups: fresh beef with decayed fish and fresh fish with decayed beef. The prime objective was to identify the decayed item using the developed electronic nose. Additionally, we tested the electronic nose using three pattern classification algorithms (artificial neural network, support vector machine and k-nearest neighbor), and compared them based on accuracy, sensitivity, and specificity. The results demonstrate that the k-nearest neighbor algorithm has the highest accuracy.
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