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Search Results: 1 - 10 of 62234 matches for " Sun Hong Yoo "
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Electroencephalography Analysis Using Neural Network and Support Vector Machine during Sleep  [PDF]
JeeEun Lee, Sun K. Yoo
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.55B018
Abstract: The purpose of this paper is to analyze sleep stages accurately using fast and simple classifiers based on the frequency domain of electroencephalography(EEG) signal. To compare and evaluate system performance, the rules of Rechtschaffen and Kales(R&K rule) were used. Parameters were extracted from preprocessing process of EEG signal as feature vectors of each sleep stage analysis system through representatives of back propagation algorithm and support vector machine (SVM). As a result, SVM showed better performance as pattern recognition system for classification of sleep stages. It was found that easier analysis of sleep stage was possible using such simple system. Since accurate estimation of sleep state is possible through combination of algorithms, we could see the potential for the classifier to be used for sleep analysis system.
Durability of viral response after off-treatment in HBeAg positive chronic hepatitis B
Myeong Jun Song,Do Seon Song,Hee Yeon Kim,Sun Hong Yoo
World Journal of Gastroenterology , 2012, DOI: 10.3748/wjg.v18.i43.6277
Abstract: AIM: To evaluate the durability in hepatitis B e antigen (HBeAg) positive chronic hepatitis B patients who discontinued antiviral treatment. METHODS: A total of 48 HBeAg positive chronic hepatitis B patients who were administered nucleoside analogues and maintained virological response for ≥ 6 mo [hepatitis B virus (HBV) DNA < 300 copies/mL and HBeAg seroconversion] before cessation of treatment were enrolled between February 2007 and January 2010. The criteria for the cessation of the antiviral treatment were defined as follows: (1) achievement of virological response; and (2) duration of consolidation therapy (≥ 6 mo). After treatment cessation, the patients were followed up at 3-6 mo intervals. The primary endpoint was serologic and virologic recurrence rates after withdrawal of antiviral treatment. Serologic recurrence was defined as reappearance of HBeAg positivity after HBeAg seroconversion. Virologic recurrence was defined as an increase in HBV-DNA level > 104 copies/mL after HBeAg seroconversion with previously undetectable HBV-DNA level. RESULTS: During the median follow-up period of 18.2 mo (range: 5.1-47.5 mo) after cessation of antiviral treatment, the cumulative serological recurrence rate was 15 % at 12 mo. The median duration between the cessation of antiviral treatment and serologic recurrence was 7.2 mo (range: 1.2-10.9 mo). Of the 48 patients with HBeAg positive chronic hepatitis, 20 (41.6%) showed virological recurrence. The cumulative virologic recurrence rates at 12 mo after discontinuing the antiviral agent were 41%. The median duration between off-treatment and virologic recurrence was 7.6 mo (range: 4.3-27.1 mo). The mean age of the virological recurrence group was older than that of the non-recurrence group (46.7 ± 12.1 years vs 38.8 ± 12.7 years, respectively; P = 0.022). Age (> 40 years) and the duration of consolidation treatment (≥ 15 mo) were significant predictive factors for offtreatment durability in the multivariate analysis [P = 0.049, relative risk (RR) 0.31, 95% CI (0.096-0.998) and P = 0.005, RR 11.29, 95% CI (2.054-65.12), respectively]. Patients with age (≤ 40 years) who received consolidation treatment (≥ 15 mo) significantly showed durability in HBeAg positive chronic hepatitis B patients (P = 0.014). These results suggest that additional treatment for more than 15 mo after HBeAg seroconversion in patients who are ≤ 40 years old may be beneficial in providing a sustained virological response. CONCLUSION: Our data suggest that HBeAg seroconversion is an imperfect end point in antiviral treatment. Long-term consol
The Design of the Fuzzy Inference System for the Determination of Attention  [PDF]
Hye Jin Kim, Sun K. Yoo
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.55B012
Abstract: In this study, by using the response speed and the number of errors resulting from the children’s concentration test through the fuzzy inference system and comparing it to the theta which is one of the EEG’s parameter to find the level of concentration. Targeting 21(Male 12, Female 9) healthy children between the ages of 10 - 14, the test was conducted one time with a duration of 14 minutes. For the first 5 minutes the children were listening to the Bach’s Air on a G string having a steady state and the next 9 minutes the children were subjected to the external stimuli audiogenic stimulation that induces attention concentration. When the number 3 was heard, children were subjected to press down on the spacebar to check the response speed and the number of errors. By conducting computerized neurocognitive function test to compare the theta wave related to the concentration with the response speed and the number of errors that determines the attention concentration through the fuzzy system, the data from 15 children out of 21 have shown the results for the concentration. In order to check the concentration level, a fuzzy inference system which was designed by the user could be used.
Characterization of the Primo-Vascular System in the Abdominal Cavity of Lung Cancer Mouse Model and Its Differences from the Lymphatic System
Jung Sun Yoo,M. Hossein Ayati,Hong Bae Kim,Wei-bo Zhang,Kwang-Sup Soh
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0009940
Abstract: Cancer growth and dissemination have been extensively studied for a long time. Nevertheless, many new observations on anatomy and histopathology of cancer events are still reported such as formation of a vasculogenic-like network inside aggressive tumors. In this research, new kinds of micro-conduits, named primo-vessels, were found inside the abdominal cavity of NCI-H460 lung cancer murine xenograft models. These vascular threads were largely distributed on the surfaces of various organs and were often connected to peritoneal tumor nodules. Histological and immunofluorescent investigations showed that the primo-vessels had characteristic features that were distinctively different from those of similar-looking lymphatic vessels. They had multiple channels surrounded with loose collageneous matrices, which is in contrast to the single-channel structure of other vascular systems. The rod-shaped nuclei aligned longitudinally along the channels were assumed to be the endothelial cells of the primo-vessels, but LYVE-1, a specific marker of lymphatics, was not expressed, which indicates a clear difference from lymphatic endothelial cells. Taken together these findings on and characterization of the novel threadlike vascular structures in cancer models may have important implications for cancer prognosis and for therapy.
bZIPDB : A database of regulatory information for human bZIP transcription factors
Taewoo Ryu, Juhyun Jung, Sunjae Lee, Ho Nam, Sun Hong, Jae Yoo, Dong-ki Lee, Doheon Lee
BMC Genomics , 2007, DOI: 10.1186/1471-2164-8-136
Abstract: We constructed a database, designated bZIPDB, containing information on 49 human bZIP TFs, by means of automated literature collection and manual curation. bZIPDB aims to provide public data required for deciphering the gene regulatory network of the human bZIP family, e.g., evaluation or reference information for the identification of regulatory modules. The resources provided by bZIPDB include (1) protein interaction data including direct binding, phosphorylation and functional associations between bZIP TFs and other cellular proteins, along with other types of interactions, (2) bZIP TF-target gene relationships, (3) the cellular network of bZIP TFs in particular cell lines, and (4) gene information and ontology. In the current version of the database, 721 protein interactions and 560 TF-target gene relationships are recorded. bZIPDB is annually updated for the newly discovered information.bZIPDB is a repository of detailed regulatory information for human bZIP TFs that is collected and processed from the literature, designed to facilitate analysis of this protein family. bZIPDB is available for public use at http://biosoft.kaist.ac.kr/bzipdb webcite.Transcription factors (TFs) are responsible for gene expression in every living organism. The bZIP family shares a basic region and a leucine zipper domain. Homo/hetero-dimerization between family members is possible through the leucine zipper domain, and the proteins bind target promoters via the basic amino acid-rich region [1]. The bZIP TFs play essential roles in several processes in eukaryotic cells, from early development to tumorigenesis. For example, JUN is an oncogene that affects diverse cellular processes including proliferation, differentiation and apoptosis [2], while CEBPA is a well-known regulator of hepatocyte and adipocyte development [3].With the assistance of high-throughput technology, such as microarray technology, several researchers have attempted to decipher the regulatory networks of bZIP TFs
A simple and accurate SNP scoring strategy based on typeIIS restriction endonuclease cleavage and matrix-assisted laser desorption/ionization mass spectrometry
Sun Hong, Seung Ji, Hwanseok Rhee, Soo Shin, Sun Hwang, Seung Lee, Soong Lee, Heung-Bum Oh, Wangdon Yoo, Soo-Ok Kim
BMC Genomics , 2008, DOI: 10.1186/1471-2164-9-276
Abstract: The assay represents an improvement over previous methods because it relies on the direct mass determination of PCR products rather than on an indirect analysis, where a base-extended or fluorescent report tag is interpreted. The RFMP strategy is simple and straightforward, requiring one restriction digestion reaction following target amplification in a single vessel. With this technology, genotypes are generated with a high call rate (99.6%) and high accuracy (99.8%) as determined by independent sequencing.The simplicity, accuracy and amenability to high-throughput screening analysis should make the RFMP assay suitable for large-scale genotype association study as well as clinical genotyping in laboratories.Genetic differences contributed to phenotypic diversity of humans or pathogens, including variation in disease susceptibility and drug response. The genotypic analysis to identify the polymorphisms that differentiate one individual or strain from another has become increasingly important as a prognostic measure of disease courses and to enable choice of more efficacious therapeutic or preventive options based on individual genetic makeup. Due to the complexity of many common, chronic diseases and quantitative traits and the confounding effects of disease heterogeneity, gene-gene interaction, and gene-environment interaction, a large number of the polymorphisms must be surveyed in numerous individuals. These progresses highlight the need for rapid, accurate, and efficient methods that permit high throughput genotyping.The most commonly used methods for genotype readout are based either on fluorescence or mass spectrometry (MS). Fluorescence readout is quite sensitive but often relies on secondary reporter systems for detection [1,2]. In contrast, MS readout has the advantage of directly detecting fragments containing the original DNA sequence information and thereby potentially reduces false positive and false negative results [3]. Even though MS did not contribu
Quantitative Analysis of Sphingomyelin by High-Performance Liquid Chromatography after Enzymatic Hydrolysis
Seunghyun Lee,Youn-Sun Lee,Kyeong-Mi Choi,Kwang-Sik Yoo,Dong-Mi Sin,Wonkyun Kim,Yong-Moon Lee,Jin-Tae Hong,Yeo-Pyo Yun,Hwan-Soo Yoo
Evidence-Based Complementary and Alternative Medicine , 2012, DOI: 10.1155/2012/396218
Abstract: Sphingomyelin is the most abundant sphingolipid in mammalian cells and is mostly present in the plasma membrane. A new analytical method using high-performance liquid chromatography (HPLC) was developed to quantify sphingomyelin in mouse plasma and tissues, 3T3-L1 cells, rat aortic smooth muscle cells, and HT-29 cells. Sphingomyelin and dihydrosphingomyelin, an internal standard, were separated by high-performance thin-layer chromatography and simultaneously hydrolyzed with sphingolipid ceramide N-deacylase and sphingomyelinase to release sphingosine and dihydrosphingosine, respectively. Sphingomyelin content was measured by HPLC following o-phthalaldehyde derivatization. Sphingomyelin concentrations in 3T3-L1 cells, rat aortic smooth muscle cells, and HT-29 cells were 60.10±0.24, 62.69±0.08, and 58.38±0.37 pmol/μg protein, respectively, whereas those in brain, kidney, and liver of ICR mice were 55.60±0.43, 43.75±0.21, and 22.26±0.14 pmol/μg protein. The sphingomyelin concentration in mouse plasma was 407.40±0.31 μM. The limits of detection and quantification for sphingomyelin were 5 and 20 pmol, respectively, in the HPLC analysis with fluorescence detection. This sensitivity was sufficient for analyzing sphingomyelin in biological samples. In conclusion, this analytical method is a sensitive and specific technique for quantifying sphingomyelin and was successfully applied to diverse biological samples with excellent reproducibility.
Soluble Fas ligand inhibits angiogenesis in rheumatoid arthritis
Wan-Uk Kim, Seung-Ki Kwok, Kyung-Hee Hong, Seung-Ah Yoo, Jin-Sun Kong, Jongseon Choe, Chul-Soo Cho
Arthritis Research & Therapy , 2007, DOI: 10.1186/ar2181
Abstract: Rheumatoid arthritis (RA) is a multi-systemic autoimmune disease of unknown etiology that is characterized by hyperplastic synovial membrane capable of destroying adjacent articular cartilage and bone [1,2]. The pathology of RA synovial membrane includes infiltration of inflammatory leukocytes, proliferation of synovial cells and extensive angiogenesis, which is collectively referred to as the rheumatoid pannus [2-4]. A critical phenomenon occurring in the early stages of synovial inflammation is angiogenesis [4,5], which commences with the activation of endothelial cells by a variety of stimuli, including pro-inflammatory cytokines and growth factors such as vascular endothelial growth factor (VEGF). The affected endothelial cells (ECs) then begin to digest the basement membrane, proliferate, migrate and eventually differentiate to form a tubular structure [6].Fas (also known as CD95) was initially discovered as a cell surface molecule that efficiently triggers death signals when bound to its ligand, Fas ligand (FasL) [7,8]. Fas is ubiquitously expressed, whereas FasL is principally expressed on activated T cells [7], natural killer cells [9], tumor cells [10], and in immune privileged sites such as the eye [11]. The Fas-FasL interaction plays a pivotal role in activation-induced cell death of T lymphocytes [12], and is responsible for the cytotoxicity of T lymphocytes [13,14] and natural killer cells [9]. Consequently, Fas and FasL are crucial components of lymphocyte homeostasis. In addition to the homeostatic regulation of the immune system, Fas and FasL are involved in tumor surveillance [15,16]. Moreover, Fas and FasL are thought to inhibit angiogenesis by inducing apoptosis of either ECs or leukocytes that provide angiogenic growth factors [17-20], although one study reported an increase in angiogenesis by Fas and FasL [21]. Similar to tumor necrosis factor (TNF)-α, FasL is cleaved from the cell surface by a metalloproteinase [22]. The released form of FasL,
Amyloid Precursor Protein Binding Protein-1 Modulates Cell Cycle Progression in Fetal Neural Stem Cells
Yuyoung Joo,Sungji Ha,Bo-Hyun Hong,Jeong a Kim,Keun-A Chang,Hyunjeong Liew,Seonghan Kim,Woong Sun,Joung-Hun Kim,Young Hae Chong,Yoo-Hun Suh,Hye-Sun Kim
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0014203
Abstract: Amyloid precursor protein binding protein-1 (APP-BP1) binds to the carboxyl terminus of the amyloid precursor protein (APP) and serves as the bipartite activation enzyme for the ubiquitin-like protein, NEDD8. In the present study, we explored the physiological role of APP-BP1 in the cell cycle progression of fetal neural stem cells. Our results show that cell cycle progression of the cells is arrested at the G1 phase by depletion of APP-BP1, which results in a marked decrease in the proliferation of the cells. This action of APP-BP1 is antagonistically regulated by the interaction with APP. Consistent with the evidence that APP-BP1 function is critical for cell cycle progression, the amount of APP-BP1 varies depending upon cell cycle phase, with culminating expression at S-phase. Furthermore, our FRET experiment revealed that phosphorylation of APP at threonine 668, known to occur during the G2/M phase, is required for the interaction between APP and APP-BP1. We also found a moderate ubiquitous level of APP-BP1 mRNA in developing embryonic and early postnatal brains; however, APP-BP1 expression is reduced by P12, and only low levels of APP-BP1 were found in the adult brain. In the cerebral cortex of E16 rats, substantial expression of both APP-BP1 and APP mRNAs was observed in the ventricular zone. Collectively, these results indicate that APP-BP1 plays an important role in the cell cycle progression of fetal neural stem cells, through the interaction with APP, which is fostered by phopshorylation of threonine 668.
Repression of FLOWERING LOCUS T Chromatin by Functionally Redundant Histone H3 Lysine 4 Demethylases in Arabidopsis
Ju-Hee Jeong,Hae-Ryong Song,Jong-Hyun Ko,Young-Min Jeong,Young Eun Kwon,Jae Hong Seol,Richard M. Amasino,Bosl Noh,Yoo-Sun Noh
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0008033
Abstract: FLOWERING LOCUS T (FT) plays a key role as a mobile floral induction signal that initiates the floral transition. Therefore, precise control of FT expression is critical for the reproductive success of flowering plants. Coexistence of bivalent histone H3 lysine 27 trimethylation (H3K27me3) and H3K4me3 marks at the FT locus and the role of H3K27me3 as a strong FT repression mechanism in Arabidopsis have been reported. However, the role of an active mark, H3K4me3, in FT regulation has not been addressed, nor have the components affecting this mark been identified. Mutations in Arabidopsis thaliana Jumonji4 (AtJmj4) and EARLY FLOWERING6 (ELF6), two Arabidopsis genes encoding Jumonji (Jmj) family proteins, caused FT-dependent, additive early flowering correlated with increased expression of FT mRNA and increased H3K4me3 levels within FT chromatin. Purified recombinant AtJmj4 protein possesses specific demethylase activity for mono-, di-, and trimethylated H3K4. Tagged AtJmj4 and ELF6 proteins associate directly with the FT transcription initiation region, a region where the H3K4me3 levels were increased most significantly in the mutants. Thus, our study demonstrates the roles of AtJmj4 and ELF6 as H3K4 demethylases directly repressing FT chromatin and preventing precocious flowering in Arabidopsis.
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