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Search Results: 1 - 10 of 20968 matches for " Heung Chul Kim "
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Ecological Niche Modeling to Estimate the Distribution of Japanese Encephalitis Virus in Asia
Robin H. Miller ,Penny Masuoka,Terry A. Klein,Heung-Chul Kim,Todd Somer,John Grieco
PLOS Neglected Tropical Diseases , 2012, DOI: 10.1371/journal.pntd.0001678
Abstract: Background Culex tritaeniorhynchus is the primary vector of Japanese encephalitis virus (JEV), a leading cause of encephalitis in Asia. JEV is transmitted in an enzootic cycle involving large wading birds as the reservoirs and swine as amplifying hosts. The development of a JEV vaccine reduced the number of JE cases in regions with comprehensive childhood vaccination programs, such as in Japan and the Republic of Korea. However, the lack of vaccine programs or insufficient coverage of populations in other endemic countries leaves many people susceptible to JEV. The aim of this study was to predict the distribution of Culex tritaeniorhynchus using ecological niche modeling. Methods/Principal Findings An ecological niche model was constructed using the Maxent program to map the areas with suitable environmental conditions for the Cx. tritaeniorhynchus vector. Program input consisted of environmental data (temperature, elevation, rainfall) and known locations of vector presence resulting from an extensive literature search and records from MosquitoMap. The statistically significant Maxent model of the estimated probability of Cx. tritaeniorhynchus presence showed that the mean temperatures of the wettest quarter had the greatest impact on the model. Further, the majority of human Japanese encephalitis (JE) cases were located in regions with higher estimated probability of Cx. tritaeniorhynchus presence. Conclusions/Significance Our ecological niche model of the estimated probability of Cx. tritaeniorhynchus presence provides a framework for better allocation of vector control resources, particularly in locations where JEV vaccinations are unavailable. Furthermore, this model provides estimates of vector probability that could improve vector surveillance programs and JE control efforts.
Distribution Characteristics, Population and Vegetation Structure of Corylopsis coreana in Korea
Choung, Heung-Lak,Dong-Ok Lim,In-Chun Hwang,Chul Hwan Kim
Journal of Ecology and Field Biology , 2007,
Abstract: This study examined the distribution, population and vegetation structure of Corylopsis coreana inSouth Korea. C. coreana is distributed around the Suncheon area, Jeollanam-do, on the southern part of theKorean Peninsula, but the species is also found in Pocheon and Gangneung, on the central and central eastparts of the peninsula. This discontinuous pattern of distribution is coupled with the unusual feature of onlygrowing on northern exposed slopes. The mean density of C. coreana populations is 35 individuals per 100 m2,ranging up to a maximum of 92 individuals per 100 m2. Cut specimens sprouted a maximum of 38 stems perplant. Based on DCA analysis, the species' habitats was divided into three types by species composition andstratification structure. These types include: habitats affected strongly by human activities, valley and mantlecommunities which are affected relatively little by human activities, and stable forests. Populations affected byartificial intervention have actually flourished, while some populations in the stable forest system have declined.We conclude that the species, now endangered, should be maintained by means of specific external interventionssuch as cutting or removal of the canopy. To this end, further ecological data should be collected throughmonitoring and research to identify appropriate interventions to support threatened C. coreana populations.
Dimerization of Translationally Controlled Tumor Protein Is Essential For Its Cytokine-Like Activity
Miyoung Kim, Hyun Jung Min, Hee Yeon Won, Heejin Park, Ji-Chul Lee, Heung-Woo Park, Junho Chung, Eun Sook Hwang, Kyunglim Lee
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0006464
Abstract: Background Translationally Controlled Tumor Protein (TCTP) found in nasal lavage fluids of allergic patients was named IgE-dependent histamine-releasing factor (HRF). Human recombinant HRF (HrHRF) has been recently reported to be much less effective than HRF produced from activated mononuclear cells (HRFmn). Methods and Findings We found that only NH2-terminal truncated, but not C-terminal truncated, TCTP shows cytokine releasing activity compared to full-length TCTP. Interestingly, only NH2-terminal truncated TCTP, unlike full-length TCTP, forms dimers through intermolecular disulfide bonds. We tested the activity of dimerized full-length TCTP generated by fusing it to rabbit Fc region. The untruncated-full length protein (Fc-HrTCTP) was more active than HrTCTP in BEAS-2B cells, suggesting that dimerization of TCTP, rather than truncation, is essential for the activation of TCTP in allergic responses. We used confocal microscopy to evaluate the affinity of TCTPs to its putative receptor. We detected stronger fluorescence in the plasma membrane of BEAS-2B cells incubated with Del-N11TCTP than those incubated with rat recombinant TCTP (RrTCTP). Allergenic activity of Del-N11TCTP prompted us to see whether the NH2-terminal truncated TCTP can induce allergic airway inflammation in vivo. While RrTCTP had no influence on airway inflammation, Del-N11TCTP increased goblet cell hyperplasia in both lung and rhinal cavity. The dimerized protein was found in sera from allergic patients, and bronchoalveolar lavage fluids from airway inflamed mice. Conclusions Dimerization of TCTP seems to be essential for its cytokine-like activity. Our study has potential to enhance the understanding of pathogenesis of allergic disease and provide a target for allergic drug development.
l-2-Oxothiazolidine-4-Carboxylic Acid or α-Lipoic Acid Attenuates Airway Remodeling: Involvement of Nuclear Factor-κB (NF-κB), Nuclear Factor Erythroid 2p45-Related Factor-2 (Nrf2), and Hypoxia-Inducible Factor (HIF)
Seoung Ju Park,Kyung Sun Lee,Su Jeong Lee,So Ri Kim,Seung Yong Park,Myoung Shin Jeon,Heung Bum Lee,Yong Chul Lee
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13077915
Abstract: Reactive oxygen species (ROS) play a crucial role in the pathogenesis of acute and chronic respiratory diseases. Antioxidants have been found to ameliorate airway inflammation and hyperresponsiveness in animal models employing short-term exposure to allergen. However, little data are available on the effect of antioxidants on airway remodeling and signaling pathways in chronic asthma. In the present study, we used a long-term exposure murine model of allergic airway disease to evaluate the effects of an antioxidant, l-2-oxothiazolidine-4-carboxylic acid (OTC) or α-lipoic acid (LA) on airway remodeling, focusing on the ROS-related hypoxia-inducible signaling. Long-term challenge of ovalbumin (OVA) increased ROS production, airway inflammation, and airway hyperresponsiveness, and developed features of airway remodeling such as excessive mucus secretion, subepithelial fibrosis, and thickening of the peribronchial smooth muscle layer. Administration of OTC or LA reduced these features of asthma, including airway remodeling, which was accompanied by suppression of transforming growth factor-β1, vascular endothelial growth factor, and T-helper 2 cytokines. In addition, OVA-induced activation of nuclear factor-κB (NF-κB), nuclear factor erythroid 2p45-related factor-2 (Nrf2), hypoxia-inducible factor (HIF)-1α, and HIF-2α was reduced by OTC or LA. Our results also showed that OTC or LA down-regulated phosphoinositide 3-kinase activity and decreased phosphorylation of p38 mitogen-activated protein kinase but not extracellular signal-regulated kinase 1/2 or c-Jun N-terminal kinase. These findings demonstrate that OTC and LA can inhibit activation of NF-κB, Nrf2, and HIF, leading to attenuate allergen-induced airway remodeling.
Genetic diversity of Imjin virus in the Ussuri white-toothed shrew (Crocidura lasiura) in the Republic of Korea, 2004-2010
Se Hun Gu, Hae Ji Kang, Luck Ju Baek, Ji Yun Noh, Heung-Chul Kim, Terry A Klein, Richard Yanagihara, Jin-Won Song
Virology Journal , 2011, DOI: 10.1186/1743-422x-8-56
Abstract: Genetically distinct hantaviruses have been discovered recently in several species of shrews (Order Soricomorpha, Family Soricidae) across four continents, including the Eurasian common shrew (Sorex araneus) [1], Chinese mole shrew (Anourosorex squamipes) [2], Therese's shrew (Crocidura theresae) [3], masked shrew (Sorex cinereus) [4], dusky shrew (Sorex monticolus) [4], northern short-tailed shrew (Blarina brevicauda) [5] and flat-skulled shrew (Sorex roboratus) [6]. Also, a novel hantavirus, named Imjin virus (MJNV), has been isolated from tissues of the Ussuri white-toothed shrew (Crocidura lasiura) captured in the Republic of Korea [7]. As demonstrated recently, Seewis virus (SWSV) harbored by the Eurasian common shrew throughout its broad geographic range exhibits geographic-specific genetic variation, similar to the phylogeography of rodent-borne hantaviruses [8,9]. A U.S. Army surveillance program, aimed at monitoring the prevalence of Hantaan virus (HTNV) infection in striped field mouse (Apodemus agrarius) populations near the demilitarized zone (DMZ) in Korea, provided an opportunity to investigate the genetic diversity and phylogeography of MJNV in the crocidurine shrew species reservoir.A total of 466 Ussuri white-toothed shrews were live caught in multiple sites, located 30 to 370 kilometers from Seoul, during March 2004 to May 2010 (Figure 1): Paju City, Yeoncheon-gun, Pocheon City, Dongducheon City, Yangpyeong-gun, Osan City, Suwon City and Pyeongtaek City in Gyeonggi province; Sincheorwon-gun and Pyeongchang-gun in Gangwon province; Gunsan City in Jeollabuk province; and Haenam-gun in Jeollanam province [10-12]. Sera collected from C. lasiura were initially diluted 1:32 in phosphate buffered saline and examined for IgG antibodies against MJNV, using the indirect immunofluorescent antibody (IFA) test [7]. In the absence of a crocidurine shrew species-specific secondary antibody, an equal mixture of fluorescein isothiocyanate-conjugated goat anti-mouse
Emergence of Japanese encephalitis virus genotype V in the Republic of Korea
Ratree Takhampunya, Heung-Chul Kim, Bousaraporn Tippayachai, Ampornpan Kengluecha, Terry A Klein, Won-Ja Lee, John Grieco, Brian P Evans
Virology Journal , 2011, DOI: 10.1186/1743-422x-8-449
Abstract: Two regions of the JEV genome were sequenced from 19 pools; the envelope gene and the nonstructural protein 5 (NS5)/3'-untranslated region (UTR). Eighteen pools of Culex tritaeniorhynchus and one pool of Cx. bitaeniorhynchus were positive for genotype I and genotype V, respectively. Sequence alignment of the complete E gene from Cx. bitaeniorhynchus showed high amino acid similarity (98.8%) to the Muar strain, characterized as the first report of genotype V, isolated from an encephalitis patient in Malaysia in 1952.This study represents the first report of JEV genotype V in the ROK. The reemergence of genotype V in Asia (China and ROK) after more than a half-century and its discovery in Cx. bitaeniorhynchus, a mosquito species previously unknown to carry JEV in the ROK, emphasizes the need for enhanced JE surveillance to monitor the dynamics of JEV strains within the region. Future findings may have implications with regard to JEV vaccination/prevention strategies.Japanese encephalitis virus (JEV) is a mosquito-borne member of the family Flaviviridae, genus Flavivirus, and a primary cause of viral encephalitis in humans within its range [1]. The positive-sense RNA viral genome is approximately 11 kb in length and is translated into three structural proteins [Capsid (C), Membrane (M), and Envelope (E)] and seven nonstructural (NS) proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5) with untranslated regions (UTR) at the 5' and 3' ends of the genome [2]. Historically, Culex tritaeniorhynchus was implicated as the primary vector of JEV in the Republic of Korea (ROK) and much of Asia [3,4]. However, JEV has since been detected in additional culicine species throughout its range, including Cx. bitaeniorhynchus from the ROK [5]. JEV strains are generally classified into five genotypes (genotypes I, II, III, IV, and V) based on similarities in the E gene nucleotide sequence [6]. Previously, only genotype I was detected on the Korean peninsula [7]. Therefore, we characteri
Perceived Organizational Support, Job Satisfaction and Employee Performance: An Chinese Empirical Study  [PDF]
Rentao Miao, Heung-Gil Kim
Journal of Service Science and Management (JSSM) , 2010, DOI: 10.4236/jssm.2010.32032
Abstract: The study investigated the generalizability of perceived organizational support and job satisfaction as positive correlations of employee performance in China. In a study conducted, 130 matched cases of 130 employees and their 34 immediate supervisors from two large-scale state-owned enterprises (SOE) were selected as participants. Well-established psychological scales measuring perceived organizational support (POS), job satisfaction, and four facets of organizational citizenship behavior (OCB) were administered. Data analyzed using zero-order correlation and hierarchical regression analysis showed positive correlations of POS and job satisfaction with work performance, and also showed independent and joint positive associations of POS and job satisfaction with OCB and each of its four dimensions.
Molecular Detection and Genotyping of Japanese Encephalitis Virus in Mosquitoes during a 2010 Outbreak in the Republic of Korea
Hyun-Ji Seo, Heung Chul Kim, Terry A. Klein, Andrew M. Ramey, Ji-Hye Lee, Soon-Goo Kyung, Jee-Yong Park, Yun Sang Cho, In-Soo Cho, Jung-Yong Yeh
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0055165
Abstract: Japanese encephalitis virus (JEV), a mosquito-borne zoonotic pathogen, is one of the major causes of viral encephalitis. To reduce the impact of Japanese encephalitis among children in the Republic of Korea (ROK), the government established a mandatory vaccination program in 1967. Through the efforts of this program only 0–7 (mean 2.1) cases of Japanese encephalitis were reported annually in the ROK during the period of 1984–2009. However, in 2010 there was an outbreak of 26 confirmed cases of Japanese encephalitis, including 7 deaths. This represented a >12-fold increase in the number of confirmed cases of Japanese encephalitis in the ROK as compared to the mean number reported over the last 26 years and a 3.7-fold increase over the highest annual number of cases during this same period (7 cases). Surveillance of adult mosquitoes was conducted during the 2010 outbreak of Japanese encephalitis in the ROK. A total of 6,328 culicine mosquitoes belonging to 12 species from 5 genera were collected at 6 survey sites from June through October 2010 and assayed by reverse-transcription polymerase chain reaction (RT-PCR) for the presence of JEV. A total of 34/371 pooled samples tested positive for JEV (29/121 Culex tritaeniorhynchus, 4/64 Cx. pipiens, and 1/26 Cx. bitaeniorhynchus) as confirmed by sequencing of the pre-membrane and envelope protein coding genes. The maximum likelihood estimates of JEV positive individuals per 1,000 culicine vectors for Cx. tritaeniorhynchus, Cx. pipiens, and Cx. bitaeniorhynchus were 11.8, 5.6, and 2.8, respectively. Sequences of the JEV pre-membrane and envelope protein coding genes amplified from the culicine mosquitoes by RT-PCR were compared with those of JEV genotypes I-V. Phylogenetic analyses support the detection of a single genotype (I) among samples collected from the ROK in 2010.
Characterization of diverse natural variants of CYP102A1 found within a species of Bacillus megaterium
Ji-Yeon Kang, So-Young Kim, Dooil Kim, Dong-Hyun Kim, Sun-Mi Shin, Sun-Ha Park, Keon-Hee Kim, Heung-Chae Jung, Jae-Gu Pan, Young Joung, Youn-Tae Chi, Ho Chae, Taeho Ahn, Chul-Ho Yun
AMB Express , 2011, DOI: 10.1186/2191-0855-1-1
Abstract: Cytochrome P450s (EC; P450 or CYP) are remarkably diverse oxygenation catalysts that are found throughout all classes of life. Although over 11,200 genes of P450s have been found in archaea, bacteria, fungi, plants, and animals (the Cytochrome P450 homepage, http://drnelson.uthsc.edu/P450.statsfile.html webcite), their evolution is not clear. An extreme diversity of substrates and catalytic reactions is characteristic of P450s (Guengerich 2001) and is considered to be the consequence of evolutionary adaptation driven by different metabolic or environmental demands in different organisms. Although most bacterial P450s do not seem to be essential to basic metabolism, they have important roles in the production of secondary metabolites and in detoxication (Kelly et al. 2005).P450 BM3 (CYP102A1) from Bacillus megaterium is a self-sufficient monooxygenase as it is fused to its redox partner, an eukaryotic-like diflavin reductase. Interestingly, sequence analysis for the P450 phylogenetic tree suggested that the CYP102A1 clusters with the eukaryotic P450s but not with other prokaryotic P450s (Lewis et al. 1998). The natural substrates of CYP102A1 are long chain fatty acids (C12 to C20), which are exclusively hydroxylated at the subterminal positions (ω-1 to ω-3) (Boddupalli et al. 1990). Furthermore, this enzyme exhibits the highest catalytic activity ever detected among P450 monooxygenase (Boddupalli et al. 1990). Engineered CYP102A1 mutants derived by directed evolution and rational design could oxidize several non-natural substrates, including pharmaceuticals, short-chain hydrocarbons, and environmental chemicals (Yun et al. 2007; Stjernschantz et al. 2008; Seifert et al. 2009). The potential of engineered CYP102A1 for biotechnological applications has been recognized (Bernhardt 2006). Recently, it was reported that CYP102A1 can be developed as a potentially versatile biocatalyst for the generation of human P450 drug metabolites (Yun et al. 2007; Kim et al. 2
Effect of charge doping on the electronic structure, orbital polarization, and structural distortion in nickelate superlattice
Heung-Sik Kim,Myung Joon Han
Physics , 2013, DOI: 10.1103/PhysRevB.91.235102
Abstract: Using first-principles density functional theory calculations, we investigated the effect of charge doping in a LaNiO$_3$/SrTiO$_3$ superlattice. The detailed analysis based on two different simulation methods for doping clearly shows that the electronic and structural properties change in a systematic way that the orbital polarization ({\it i.e.} relative occupation of two Ni-$e_g$ orbitals) is reduced and the Ni to apical oxygen distance enlarged as the number of doped electrons increases. Also, the rotation angles of the NiO$_6$/TiO$_6$ octahedra strongly and systematically depend on the doping so that the angle $\gamma$ gradually decreases whereas the $\alpha$ and $\beta$ increase as a function of electron doping. Further analysis shows that the electron (hole) doping can play a similar role with the compressive (tensile) strain for the octahedral rotations. Our results not only suggest a possible way to control the orbital and structural property by means of charge doping, but also provide useful information to understand the experiments under various doping situations such as oxygen vacancy.
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