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Search Results: 1 - 10 of 25747 matches for " Geun-Cheol Lee "
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Identification and Functional Analysis of Light-Responsive Unique Genes and Gene Family Members in Rice
Ki-Hong Jung,Jinwon Lee,Chris Dardick,Young-Su Seo,Peijian Cao,Patrick Canlas,Jirapa Phetsom,Xia Xu,Shu Ouyang,Kyungsook An,Yun-Ja Cho,Geun-Cheol Lee,Yoosook Lee,Gynheung An,Pamela C. Ronald
PLOS Genetics , 2008, DOI: 10.1371/journal.pgen.1000164
Abstract: Functional redundancy limits detailed analysis of genes in many organisms. Here, we report a method to efficiently overcome this obstacle by combining gene expression data with analysis of gene-indexed mutants. Using a rice NSF45K oligo-microarray to compare 2-week-old light- and dark-grown rice leaf tissue, we identified 365 genes that showed significant 8-fold or greater induction in the light relative to dark conditions. We then screened collections of rice T-DNA insertional mutants to identify rice lines with mutations in the strongly light-induced genes. From this analysis, we identified 74 different lines comprising two independent mutant lines for each of 37 light-induced genes. This list was further refined by mining gene expression data to exclude genes that had potential functional redundancy due to co-expressed family members (12 genes) and genes that had inconsistent light responses across other publicly available microarray datasets (five genes). We next characterized the phenotypes of rice lines carrying mutations in ten of the remaining candidate genes and then carried out co-expression analysis associated with these genes. This analysis effectively provided candidate functions for two genes of previously unknown function and for one gene not directly linked to the tested biochemical pathways. These data demonstrate the efficiency of combining gene family-based expression profiles with analyses of insertional mutants to identify novel genes and their functions, even among members of multi-gene families.
Assessing probe-specific dye and slide biases in two-color microarray data
Ruixiao Lu, Geun-Cheol Lee, Michael Shultz, Chris Dardick, Kihong Jung, Jirapa Phetsom, Yi Jia, Robert H Rice, Zelanna Goldberg, Patrick S Schnable, Pamela Ronald, David M Rocke
BMC Bioinformatics , 2008, DOI: 10.1186/1471-2105-9-314
Abstract: We develop a procedure for quantifying the extent of probe-specific dye and slide bias in two-color microarrays. The primary output is a graphical diagnostic of the extent of the bias which called ECDF (Empirical Cumulative Distribution Function), though numerical results are also obtained.We show that the dye and slide biases were high for human and rice genomic arrays in two gene expression facilities, even after the standard intensity-based normalization, and describe how this diagnostic allowed the problems causing the probe-specific bias to be addressed, and resulted in important improvements in performance. The R package LMGene which contains the method described in this paper has been available to download from Bioconductor.One of the major tasks in the analysis of high-dimensional biological assay data such as gene expression arrays is to detect differential expression from a comparative experiment. Using two-color microarrays is supposed to adjust for the noise introduced by many factors on the same slide including spot size and conformation. Standard data pre-processing methods for two-color data include the normalization of the differences between two dye channels, after which most users believe the dye bias has effectively been removed and that the normalized measurements are now relatively free of dye bias. However, probe specific dye-bias and slide-bias can be high even after standard normalization, which may cause problems when one expects to identify many statistically significantly differentially expressed genes.This dye bias has received some recent attention [1-8]. These papers generally provide computational methods to detect and correct for dye bias, at least in some circumstances. Correction can include use of gene-specific dye bias terms in an ANOVA, for example. Even when this is done, dye bias may still cause significant harm by introducing large amounts of noise that prevent identification of significantly differentially expressed genes. We
Is obesity associated with gastropharyngeal reflux disease?
Cheol Woong Choi, Gwang Ha Kim, Chul Soo Song, Soo Geun Wang, Byung Joo Lee, Hoseok I, Dae Hwan Kang, Geun Am Song
World Journal of Gastroenterology , 2008,
Abstract: AIM: To examine the association between obesity and gastropharyngeal reflux disease (GPRD) as well as gastroesophageal reflux disease (GERD)METHODS: We conducted a cross-sectional study of consecutive patients undergoing ambulatory 24-h dual-probe pH monitoring from July 2003 to December 2006. The association between body mass index (BMI) and parameters about gastroesophageal or gastropharyngeal reflux was examined in univariate and multivariate analyses.RESULTS: A total of 769 patients (307 men and 462 women; mean age 50.7 years) were finally enrolled. Most variables showing gastroesophageal reflux was higher in the obese patients than the patients with normal BMI. There was no difference in all the variables showing gastropharyngeal reflux according to the BMI. After adjustment for age, sex, alcohol intake and smoking, obese patients demonstrated an about 2-fold increase in risk of GERD compared with patients with normal BMI (OR, 1.9; 95 CI, 1.3-2.9), but overweight patients did not demonstrate increased risk of GERD (OR, 1.2; 95 CI, 0.8-1.7). Both obese patients and overweight patients did not demonstrated increased risk of GPRD compared with patients with normal BMI (OR, 1.1; 95 CI, 0.8-1.7; and OR, 0.9; 95 CI, 0.6-1.3, respectively).CONCLUSION: Obesity is not associated with GPRD reflux while it is associated with GERD.
Regional distribution of perceived temperatures estimated by the human heat budget model (the Klima-Michel model) in South Korea
Regional Distribution of Perceived Temperatures Estimated by the Human Heat Budget Model (the Klima-Michel Model) in South Korea

Jiyoung Kim,Kyu Rang Kim,Byoung-Cheol Choi,Dae-Geun Lee,Jeong-Sik Kim,
Jiyoung KIM
,Kyu Rang KIM,Byoung-Cheol CHOI,Dae-Geun LEE,Jeong-Sik KIM

大气科学进展 , 2009,
Abstract: The regional distribution of perceived temperatures (PT) for 28 major weather stations in South Korea during the past 22 years (1983--2004) was investigated by employing a human heat budget model, the Klima-Michel model. The frequencies of a cold stress and a heat load by each region were compared. The sensitivity of PT in terms of the input of synoptic meteorological variables were successfully tested. Seogwipo in Jeju Island appears to be the most comfortable city in Korea. Busan also shows a high frequency in the comfortable PT range. The frequency of the thermal comfort in Seoul is similar to that of Daejeon with a relatively low frequency. In this study, inland cities like Daegu and Daejeon had very hot thermal sensations. Low frequencies of hot thermal sensations appeared in coastal cities (e.g., Busan, Incheon, and Seogwipo). Most of the 28 stations in Korea exhibited a comfort thermal sensation over 40% in its frequency, except for the mountainous regions. The frequency of a heat load is more frequent than that of a cold stress. There are no cities with very cold thermal sensations. In this study, we found the decreasing trend of mortality with an increasing PT. If the PT is over any critical temperature point, however, the mortality rate increases again. The mortality variation with the PT of a station seems to be associated with the latitudinal location of the station, implying that it results from a regional acclimation effect of inhabitants.
Elicitation of Induced Resistance against Pectobacterium carotovorum and Pseudomonas syringae by Specific Individual Compounds Derived from Native Korean Plant Species
Geun Cheol Song,Shi Yong Ryu,Young Sup Kim,Ji Young Lee,Jung Sup Choi,Choong-Min Ryu
Molecules , 2013, DOI: 10.3390/molecules181012877
Abstract: Plants have developed general and specific defense mechanisms for protection against various enemies. Among the general defenses, induced resistance has distinct characteristics, such as broad-spectrum resistance and long-lasting effectiveness. This study evaluated over 500 specific chemical compounds derived from native Korean plant species to determine whether they triggered induced resistance against Pectobacterium carotovorum supsp. carotovorum ( Pcc) in tobacco ( Nicotiana tabacum) and Pseudomonas syringae pv. tomato ( Pst) in Arabidopsis thaliana. To select target compound(s) with direct and indirect (volatile) effects, a new Petri-dish-based in vitro disease assay system with four compartments was developed. The screening assay showed that capsaicin, fisetin hydrate, jaceosidin, and farnesiferol A reduced the disease severity significantly in tobacco. Of these four compounds, capsaicin and jaceosidin induced resistance against Pcc and Pst, which depended on both salicylic acid (SA) and jasmonic acid (JA) signaling, using Arabidopsis transgenic and mutant lines, including npr1 and NahG for SA signaling and jar1 for JA signaling. The upregulation of the PR2 and PDF1. 2 genes after Pst challenge with capsaicin pre-treatment indicated that SA and JA signaling were primed. These results demonstrate that capsaicin and jaceosidin can be effective triggers of strong induced resistance against both necrotrophic and biotrophic plant pathogens.
FER Performance in the IEEE 802.11 a/g/n Wireless LAN over Fading Channel  [PDF]
Ha Cheol Lee
Communications and Network (CN) , 2013, DOI: 10.4236/cn.2013.53B1003
Abstract: This paper explores and compares FER (Frame Error Rate) of a MAC (Medium Access Control) layer in the IEEE 802.11 a/g/n wireless LAN. It is evaluated under the fading wireless channel, using theoretical analysis method. It is analyzed by using the number of stations with both variable payload size and mobile speed on the condition that fading margin and transmission probability are fixed. Especially, in the IEEE 802.11n, A-MSDU (MAC Service Data Unit Aggregation) scheme is considered and the number of subframe is used as the variable parameter. In the IEEE802.11a/g wireless LAN, fixed wireless channel is assumed to be Rayleigh fading channel. Mobile wireless channel is assumed to be flat fading Rayleigh channel with Jake spectrum. The channel is in fading states or inter-fading states by evaluating a certain threshold value of received signal power level. If and only if the whole frame is in inter-fading state, there is the successful frame transmission. If any part of frame is in fading duration, the frame is received in error.
Asymmetric Magnetic Domain-Wall Motion by the Dzyaloshinskii-Moriya Interaction
Soong-Geun Je,Duck-Ho Kim,Sang-Cheol Yoo,Byoung-Chul Min,Kyung-Jin Lee,Sug-Bong Choe
Physics , 2013, DOI: 10.1103/PhysRevB.88.214401
Abstract: We demonstrate here that ultrathin ferromagnetic Pt/Co/Pt films with perpendicular magnetic anisotropy exhibit a sizeable Dzyaloshinskii-Moriya interaction (DMI) effect. Such a DMI effect modifies the domain-wall (DW) energy density and consequently, results in an asymmetric DW expansion driven by an out-of-plane magnetic field under an in-plane magnetic field bias. From an analysis of the asymmetry, the DMI effect is estimated to be strong enough for the DW to remain in the N\'eel-type configuration in contrast to the general expectations of these materials. Our findings emphasize the critical role of the DMI effect on the DW dynamics as the underlying physics of the asymmetries that are often observed in spin-transfer-related phenomena.
Stem cell treatment for patients with autoimmune disease by systemic infusion of culture-expanded autologous adipose tissue derived mesenchymal stem cells
Jeong Chan Ra, Sung Keun Kang, Il Seob Shin, Hyeong Geun Park, Sang Aun Joo, Jeong Geun Kim, Byeong-Cheol Kang, Yong Soon Lee, Ken Nakama, Min Piao, Bertram Sohl, Andras Kurtz
Journal of Translational Medicine , 2011, DOI: 10.1186/1479-5876-9-181
Abstract: In the 21st century, live expectancy has rapidly progressed as has the number of previously uncommon diseases with no treatment. Stem cell based therapies are suggested to be able to repair and regenerate tissues in diseases associated with age, changed life style and environmental exposure, such as autoimmune disease and stroke. In particular, mesenchymal stem cells (MSCs) have been applied to treat these diseases [1-3]. However, the lack of optimized culture protocols for achieving sufficient number of cells, safety issues concerning ex-vivo-expanded cells, the possible reduction in potency of stem cells derived from aged people and patients with autoimmune disease has put into question clinical applications of autologous stem cells in these patients.In order to apply human autologous adipose tissue derived MSC (hAdMSC) in the clinical setting, we developed a standardized protocol to isolate and culture-expand AdMSC from minimal amounts of fat in vitro, achieving sufficient cell numbers for multiple therapeutic inventions [4]. Expanded AdMSCs maintained the potency for effective differentiation independently of donor age and disease status [5]. The confirmed genetic stability and in vivo safety of ex-vivo-expanded hAdMSCs in animal models and patients [4] indicate that AdMSCs from older persons are applicable for autologous therapy and are comparable to those derived from young donors [5]. Furthermore, we investigated the migration ability of hAdMSCs and their in vivo homing in animal model after systemic infusion.MSC include a number of stem cells with an inherent ability for self-renewal and differentiation potential for mesodermal and other embryonic lineages, including adipocytes, osteocytes, chondrocytes, hepatocytes, neurons, muscle cells and epithelial cells [6-8], depending on the surrounding microenvironment. A large body of evidence demonstrated that MSC commonly have immunomodulatory and anti-inflammatory properties [9-12]. While the differentiation pro
Two Volatile Organic Compounds Trigger Plant Self-Defense against a Bacterial Pathogen and a Sucking Insect in Cucumber under Open Field Conditions
Geun Cheol Song,Choong-Min Ryu
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14059803
Abstract: Systemic acquired resistance (SAR) is a plant self-defense mechanism against a broad-range of pathogens and insect pests. Among chemical SAR triggers, plant and bacterial volatiles are promising candidates for use in pest management, as these volatiles are highly effective, inexpensive, and can be employed at relatively low concentrations compared with agrochemicals. However, such volatiles have some drawbacks, including the high evaporation rate of these compounds after application in the open field, their negative effects on plant growth, and their inconsistent levels of effectiveness. Here, we demonstrate the effectiveness of volatile organic compound (VOC)-mediated induced resistance against both the bacterial angular leaf spot pathogen, Pseudononas syringae pv. lachrymans, and the sucking insect aphid, Myzus persicae, in the open field. Using the VOCs 3-pentanol and 2-butanone where fruit yields increased gave unexpectedly, a significant increase in the number of ladybird beetles, Coccinella septempunctata, a natural enemy of aphids. The defense-related gene CsLOX was induced by VOC treatment, indicating that triggering the oxylipin pathway in response to the emission of green leaf volatiles can recruit the natural enemy of aphids. These results demonstrate that VOCs may help prevent plant disease and insect damage by eliciting induced resistance, even in open fields.
Increased intestinal macromolecular permeability and urine nitrite excretion associated with liver cirrhosis with ascites
Soong Lee, Seung-Cheol Son, Moon-Jong Han, Woo-Jin Kim, Soo-Hyun Kim, Hye-Ran Kim, Woo-Kyu Jeon, Ki-Hong Park, Myung-Geun Shin
World Journal of Gastroenterology , 2008,
Abstract: AIM: To determine intestinal permeability, the serum tumor necrosis factor (TNF)-α level and urine nitric oxide (NO) metabolites are altered in liver cirrhosis (LC) with or without ascites.METHODS: Fifty-three patients with LC and 26 healthy control subjects were enrolled in the study. The intestinal permeability value is expressed as the percentage of polyethylene glycol (PEG) 400 and 3350 retrieval in 8-h urine samples as determined by high performance liquid chromatography. Serum TNF-α concentrations and urine NO metabolites were determined using an enzyme-linked immunosorbent assay (ELISA) and Greiss reaction method, respectively.RESULTS: The intestinal permeability index was significantly higher in patients with LC with ascites than in healthy control subjects or patients with LC without ascites (0.88 ± 0.12 vs 0.52 ± 0.05 or 0.53 ± 0.03, P < 0.05) and correlated with urine nitrite excretion (r = 0.98). Interestingly, the serum TNF-α concentra-tion was significantly higher in LC without ascites than in control subjects or in LC with ascites (198.9 ± 55.8 pg/mL vs 40.9 ± 12.3 pg/mL or 32.1 ± 13.3 pg/mL, P < 0.05). Urine nitrite excretion was significantly higher in LC with ascites than in the control subjects or in LC without ascites (1170.9 ± 28.7 μmol/L vs 903.1 ± 55.1 μmol/L or 956.7 ± 47.7 μmol/L, P < 0.05).CONCLUSION: Increased intestinal macromolecular permeability and NO is probably of importance in the pathophysiology and progression of LC with ascites, but the serum TNF-α concentration was not related to LC with ascites.
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