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Search Results: 1 - 10 of 31765 matches for " Sun-Hwa Cho "
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Turbo Warrants under Hybrid Stochastic and Local Volatility
Min-Ku Lee,Ji-Hun Yoon,Jeong-Hoon Kim,Sun-Hwa Cho
Abstract and Applied Analysis , 2014, DOI: 10.1155/2014/407145
Abstract: This paper considers the pricing of turbo warrants under a hybrid stochastic and local volatility model. The model consists of the constant elasticity of variance model incorporated by a fast fluctuating Ornstein-Uhlenbeck process for stochastic volatility. The sensitive structure of the turbo warrant price is revealed by asymptotic analysis and numerical computation based on the observation that the elasticity of variance controls leverage effects and plays an important role in characterizing various phases of volatile markets. 1. Introduction Turbo warrants, which appeared first in Germany in late 2001, have experienced a considerable growth in Northern Europe and Hong Kong. They are special types of knockout barrier options in which the rebate is calculated as another exotic option. For one thing, this contract has a low vega so that the option price is less sensitive to the change of the implied volatility of the security market, and for another, it is highly geared owing to the possibility of knockout. Closed form expression for the price has been presented by Eriksson [1] under geometric Brownian motion (GBM) for the underlying security. It is well-known that the assumption of the GBM for the underlying security price in the Black-Scholes model [2] does not capture many empirical lines of evidence appeared in financial markets. Maybe, the two most significant shortcomings of the model's assumption lie in flat implied volatility, whereas the volatility fluctuates depending upon market conditions and the underestimation of extreme moves, yielding tail risk. So, there have been a lot of alternative underlying models developed to extend the GBM and overcome these problems. Local volatility models are one type of them, where the volatility depends on the price level of the underlying security itself. The most well-known local volatility model is the constant elasticity of variance (CEV) model in which the volatility is given by a power function of the underlying security price. It has been proposed by Cox [3] and Cox and Ross [4]. Another version of volatility models has been developed by assuming security's volatility to be a random process governed by another state variables such as the tendency of volatility to revert to some long-run mean value, the variance of the volatility process itself, and so forth. This type of models is called (pure) stochastic volatility models. The models developed by Heston [5] and Fouque et al. [6] are popular ones among others in this category. Also, there is another type of generalized models for the underlying
Effect of Activated Charcoal Fibers on the Survival of the House Dust Mite, Dermatophagoides pteronyssinus: A Pilot Study
Hae-Seon Nam,Sun-Hwa Lee,Young-Jin Choi,Joon-Soo Park,Moon-Kyun Cho,Sang-Han Lee,Julian Crane,Robert Siebers
ISRN Allergy , 2012, DOI: 10.5402/2012/868170
Abstract: House dust mites produce potent allergens that exacerbate asthma in sensitized patients, whom are recommended to practice allergen avoidance within their home environment. We tested the effect of activated charcoal impregnated fibers on house dust mite survival. One hundred live adult house dust mites (Dermatophagoides pteronyssinus) were added to eight culture dishes preequilibrated at room temperature ( ) and 70% humidity ( ) containing house dust mite food and active charcoal fibers. At 10 minute intervals, live and dead house dust mites were counted. All house dust mites instantly attached to the activated charcoal fibers and started to shrink almost immediately. There were no live house dust mites present as early as 40 minutes in some dishes while after 190 minutes all house dust mites were dead. In conclusion, activated charcoal fibers, if incorporated into bedding items, have the potential to control house dust mites in the indoor environment. 1. Introduction House dust mites (HDMs) produce potent allergens that can exacerbate asthma in sensitized patients [1]. HDM sensitized patients are generally recommended to practice allergen avoidance within their home environment, especially in the bedroom where they spend about one-third of their lives in close proximity to allergen-laden bedding items [2]. Commonly recommended HDM avoidance methods include covering all bedding with HDM impermeable materials. Although various studies have shown clinical efficacy of occlusive covers [3, 4], a recent large trial concluded they were ineffective [5]. Additionally, a recent systematic review has concluded that chemical and physical methods for reducing HDM allergens are not recommended [6]. However, this study has been criticized regarding its inclusion and exclusion criteria and evaluation of the studies [7]. Occlusive bedding covers, recommended by allergy and asthma societies worldwide, are expensive and alternative methods have been sought to reduce exposure to HDM allergens in bedding. We have previously shown that activated charcoal powder added to HDM food suppresses breeding of the HDM, Dermatophagoides pteronyssinus in the laboratory setting thus offering a potential new method for HDM control [8]. However, activated charcoal powder is messy and difficult to incorporate into bedding items. We therefore tested the effects of fibers impregnated with activated charcoal on HDM survival. 2. Methods To each of eight culture dishes, diameter 50?mm, height 15?mm (Corning, USA), 0.02?g of HDM food consisting of wheat germ (40%), granulated yeast (40%),
Role of Amphipathic Helix of a Herpesviral Protein in Membrane Deformation and T Cell Receptor Downregulation
Chan-Ki Min,Sun-Young Bang,Bon-A Cho,Yun-Hui Choi,Jae-Seong Yang,Sun-Hwa Lee,Seung-Yong Seong,Ki Woo Kim,Sanguk Kim,Jae Ung Jung,Myung-Sik Choi,Ik-Sang Kim,Nam-Hyuk Cho
PLOS Pathogens , 2008, DOI: 10.1371/journal.ppat.1000209
Abstract: Lipid rafts are membrane microdomains that function as platforms for signal transduction and membrane trafficking. Tyrosine kinase interacting protein (Tip) of T lymphotropic Herpesvirus saimiri (HVS) is targeted to lipid rafts in T cells and downregulates TCR and CD4 surface expression. Here, we report that the membrane-proximal amphipathic helix preceding Tip's transmembrane (TM) domain mediates lipid raft localization and membrane deformation. In turn, this motif directs Tip's lysosomal trafficking and selective TCR downregulation. The amphipathic helix binds to the negatively charged lipids and induces liposome tubulation, the TM domain mediates oligomerization, and cooperation of the membrane-proximal helix with the TM domain is sufficient for localization to lipid rafts and lysosomal compartments, especially the mutivesicular bodies. These findings suggest that the membrane-proximal amphipathic helix and TM domain provide HVS Tip with the unique ability to deform the cellular membranes in lipid rafts and to downregulate TCRs potentially through MVB formation.
Characterization of mouse clonal mesenchymal stem cell lines established by subfractionation culturing method
Myung-Shin Jeon,Tac-Ghee Yi,Hyun-Ja Lim,Sun-Hwa Moon
World Journal of Stem Cells , 2011, DOI: 10.4252/wjsc.v3.i8.70
Abstract: AIM: To characterize single-cell-derived mouse clonal mesenchymal stem cells (mcMSCs) established with bone marrow samples from three different mouse strains. METHODS: We established mcMSC lines using subfractionation culturing method from bone marrow samples obtained from long bones. These lines were characterized by measuring cell growth, cell surface epitopes, differentiation potential, lineage-specific gene expression and T-cell suppression capability. Nonclonal MSCs isolated by the conventional gradient centrifugation method were used as controls. RESULTS: All mcMSC lines showed typical nonclonal MSC-like spindle shape morphology. Lines differed in optimal growth density requirement. Cell surface epitope profiles of these mcMSC lines were similar to those of nonclonal MSCs. However, some lines exhibited different expression levels in a few epitopes, such as CD44 and CD105. Differentiation assays showed that 90% of the mcMSC lines were capable of differentiating into adipogenic and/or chondrogenic lineages, but only 20% showed osteogenic lineage differentiation. T-cell suppression analysis showed that 75% of the lines exhibited T-cell suppression capability. CONCLUSION: mcMSC lines have similar cell morphology and cell growth rate but exhibit variations in their cell surface epitopes, differentiation potential, lineage-specific gene expression and T-cell suppression capability.
Determination of the Local Symmetry and the Multiferroic-ferromagnetic Crossover in Ni3-xCoxV2O8 by using Raman Scattering Spectroscopy
Yu-Seong Seo,Sun-Hwa Kim,Jai Seok Ahn,Il-Kyoung Jeong
Physics , 2013, DOI: 10.3938/jkps.62.116
Abstract: Comprehensive vibrational studies on the multiferroic-to-normal-ferromagnetic crossover in isostructural Ni3-xCoxV2O8 (NCVO, x = 0 - 3.0) are performed using Raman scattering spectroscopy. The systematically red-shifted phonon modes are discussed in terms of the mode Gr\"uneisen parameters, and are interpreted as a chemical pressure effect. In addition, we present evidence that the local symmetry is broken in the multiferroic phase.
Utilization of a ts-sacB selection system for the generation of a Mycobacterium avium serovar-8 specific glycopeptidolipid allelic exchange mutant
Vida R Irani, Sun-Hwa Lee, Torsten M Eckstein, Julia M Inamine, John T Belisle, Joel N Maslow
Annals of Clinical Microbiology and Antimicrobials , 2004, DOI: 10.1186/1476-0711-3-18
Abstract: To be able to study the role of the GPL in M. avium pathogenesis, a ts-sacB selection system, not previously used in M. avium, was employed as a means to achieve homologous recombination for the rhamnosyltransferase (rtfA) gene of a pathogenic serovar 8 strain of M. avium to prevent addition of serovar-specific sugars to rhamnose of the fatty acyl-peptide backbone of GPL. The genotype of the resultant rtfA mutant was confirmed by polymerase chain reaction and southern hybridization. Disruption in the proximal sugar of the haptenic oligosaccharide resulted in the loss of serovar specific GPL with no change in the pattern of non-serovar specific GPL moieties as shown by thin layer chromatography and gas chromatography/mass spectrometry. Complementation of wild type (wt) rtfA in trans through an integrative plasmid restored serovar-8 specific GPL expression identical to wt serovar 8 parent strain.In this study, we affirm our results that rtfA encodes an enzyme responsible for the transfer of Rha to 6d-Tal and provide evidence of a second allelic exchange mutagenesis system suitable for M. avium.We report the second allelic exchange system for M. avium utilizing ts-sacB as double-negative and xylE as positive counter-selection markers, respectively. This system of allelic exchange would be especially useful for M. avium strains that demonstrate significant isoniazid (INH) resistance despite transformation with katG. Through the construction of mutants in GPL or other mycobacterial components, their roles in M. avium pathogenesis, biosynthesis, or drug resistance can be studied in a consistent manner.Mycobacterium avium is a frequent cause of disseminated infection among patients with end-stage AIDS [9,11,19]. M. avium can also present with a similar spectrum of pulmonary and extra pulmonary syndromes as Mycobacterium tuberculosis [27] including the establishment of latent infection that can reactivate concomitant with immune suppression [13]. While significant advances
c-FLIP-Short Reduces Type I Interferon Production and Increases Viremia with Coxsackievirus B3
Iwona A. Buskiewicz, Andreas Koenig, Brian Roberts, Jennifer Russell, Cuixia Shi, Sun-Hwa Lee, Jae U. Jung, Sally A. Huber, Ralph C. Budd
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096156
Abstract: Cellular FLIP (c-FLIP) is an enzymatically inactive paralogue of caspase-8 and as such can block death receptor-induced apoptosis. However, independent of death receptors, c-FLIP-Long (c-FLIPL) can heterodimerize with and activate caspase-8. This is critical for promoting the growth and survival of T lymphocytes as well as the regulation of the RIG-I helicase pathway for type I interferon production in response to viral infections. Truncated forms of FLIP also exist in mammalian cells (c-FLIPS) and certain viruses (v-FLIP), which lack the C-terminal domain that activates caspase-8. Thus, the ratio of c-FLIPL to these short forms of FLIP may greatly influence the outcome of an immune response. We examined this model in mice transgenically expressing c-FLIPS in T cells during infection with Coxsackievirus B3 (CVB3). In contrast to our earlier findings of reduced myocarditis and mortality with CVB3 infection of c-FLIPL-transgenic mice, c-FLIPS-transgenic mice were highly sensitive to CVB3 infection as manifested by increased cardiac virus titers, myocarditis score, and mortality compared to wild-type C57BL/6 mice. This observation was paralleled by a reduction in serum levels of IL-10 and IFN-α in CVB3-infected c-FLIPS mice. In vitro infection of c-FLIPS T cells with CVB3 confirmed these results. Furthermore, molecular studies revealed that following infection of cells with CVB3, c-FLIPL associates with mitochondrial antiviral signaling protein (MAVS), increases caspase-8 activity and type I IFN production, and reduces viral replication, whereas c-FLIPS promotes the opposite phenotype.
Genetic Modification of the Soybean to Enhance the β-Carotene Content through Seed-Specific Expression
Mi-Jin Kim, Jae Kwang Kim, Hye Jeong Kim, Jung Hun Pak, Jai-Heon Lee, Doh-Hoon Kim, Hong Kyu Choi, Ho Won Jung, Jeong-Dong Lee, Young-Soo Chung, Sun-Hwa Ha
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0048287
Abstract: The carotenoid biosynthetic pathway was genetically manipulated using the recombinant PAC (Phytoene synthase-2A-Carotene desaturase) gene in Korean soybean (Glycine max L. cv. Kwangan). The PAC gene was linked to either the β-conglycinin (β) or CaMV-35S (35S) promoter to generate β-PAC and 35S-PAC constructs, respectively. A total of 37 transgenic lines (19 for β-PAC and 18 for 35S-PAC) were obtained through Agrobacterium-mediated transformation using the modified half-seed method. The multi-copy insertion of the transgene was determined by genomic Southern blot analysis. Four lines for β-PAC were selected by visual inspection to confirm an orange endosperm, which was not found in the seeds of the 35S-PAC lines. The strong expression of PAC gene was detected in the seeds of the β-PAC lines and in the leaves of the 35S-PAC lines by RT-PCR and qRT-PCR analyses, suggesting that these two different promoters function distinctively. HPLC analysis of the seeds and leaves of the T2 generation plants revealed that the best line among the β-PAC transgenic seeds accumulated 146 μg/g of total carotenoids (approximately 62-fold higher than non-transgenic seeds), of which 112 μg/g (77%) was β-carotene. In contrast, the level and composition of the leaf carotenoids showed little difference between transgenic and non-transgenic soybean plants. We have therefore demonstrated the production of a high β-carotene soybean through the seed-specific overexpression of two carotenoid biosynthetic genes, Capsicum phytoene synthase and Pantoea carotene desaturase. This nutritional enhancement of soybean seeds through the elevation of the provitamin A content to produce biofortified food may have practical health benefits in the future in both humans and livestock.
Echovirus 30 Induced Neuronal Cell Death through TRIO-RhoA Signaling Activation
June-Woo Lee, Sang-Gu Yeo, Byung-Hak Kang, Hoe-Kyu Lee, Jin-Won Kim, Sun-Hwa Lee, Ki-Sang Kim, Doo-Sung Cheon
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036656
Abstract: Background Echovirus 30 (Echo30) is one of the most frequently identified human enteroviruses (EVs) causing aseptic meningitis and encephalitis. However the mechanism underlying the pathogenesis of Echo30 infection with significant clinical outcomes is not completely understood. The aim of this investigation is to illustrate molecular pathologic alteration in neuronal cells induced by Echo30 infection using clinical isolate from young patient with neurologic involvement. Methodology/Principal Findings To characterize the neuronal cellular response to Echo30 infection, we performed a proteomic analysis based on two-dimensional gel electrophoresis (2-DE) and MALDI-TOF/TOF Mass Spectrophotometric (MS) analysis. We identified significant alteration of several protein expression levels in Echo30-infected SK-N-SH cells. Among these proteins, we focused on an outstanding up-regulation of Triple functional domain (TRIO) in Echo30-infected SK-N-SH cells. Generally, TRIO acts as a key component in the regulation of axon guidance and cell migration. In this study, we determined that TRIO plays a role in the novel pathways in Echo30 induced neuronal cell death. Conclusions/Significance Our finding shows that TRIO plays a critical role in neuronal cell death by Echo30 infection. Echo30 infection activates TRIO-guanine nucleotide exchange factor (GEF) domains (GEFD2) and RhoA signaling in turn. These results suggest that Echo30 infection induced neuronal cell death by activation of the TRIO-RhoA signaling. We expect the regulation of TRIO-RhoA signaling may represent a new therapeutic approach in treating aseptic meningitis and encephalitis induced by Echo30.
Fibroblast Growth Factor-2 Induced by Enriched Environment Enhances Angiogenesis and Motor Function in Chronic Hypoxic-Ischemic Brain Injury
Jung Hwa Seo, Ji Hea Yu, Hwal Suh, Myung-Sun Kim, Sung-Rae Cho
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0074405
Abstract: This study aimed to investigate the effects of enriched environment (EE) on promoting angiogenesis and neurobehavioral function in an animal model of chronic hypoxic-ischemic (HI) brain injury. HI brain damage was induced in seven day-old CD-1? mice by unilateral carotid artery ligation and exposure to hypoxia (8% O2 for 90 min). At six weeks of age, the mice were randomly assigned to either EE or standard cages (SC) for two months. Rotarod, forelimb-use asymmetry, and grip strength tests were performed to evaluate neurobehavioral function. In order to identify angiogenic growth factors regulated by EE, an array-based multiplex ELISA assay was used to measure the expression in frontal cortex, striatum, and cerebellum. Among the growth factors, the expression of fibroblast growth factor-2 (FGF-2) was confirmed using western blotting. Platelet endothelial cell adhesion molecule-1 (PECAM-1) and α-smooth muscle actin (α-SMA) were also evaluated using immunohistochemistry. As a result, mice exposed to EE showed significant improvements in rotarod and ladder walking performances compared to SC controls. The level of FGF-2 was significantly higher in the frontal cortex of EE mice at 8 weeks after treatment in multiplex ELISA and western blot. On the other hand, FGF-2 in the striatum significantly increased at 2 weeks after exposure to EE earlier than in the frontal cortex. Expression of activin A was similarly upregulated as FGF-2 expression pattern. Particularly, all animals treated with FGF-2 neutralizing antibody abolished the beneficial effect of EE on motor performance relative to mice not given anti-FGF-2. Immunohistochemistry showed that densities of α-SMA+ and PECAM-1+ cells in frontal cortex, striatum, and hippocampus were significantly increased following EE, suggesting the histological findings exhibit a similar pattern to the upregulation of FGF-2 in the brain. In conclusion, EE enhances endogenous angiogenesis and neurobehavioral functions mediated by upregulation of FGF-2 in chronic hypoxic-ischemic brain injury.
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