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Search Results: 1 - 10 of 40563 matches for " Hong-kyu Choi "
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Cross-Family Translational Genomics of Abiotic Stress-Responsive Genes between Arabidopsis and Medicago truncatula
Daejin Hyung, Chaeyoung Lee, Jin-Hyun Kim, Dongwoon Yoo, Young-Su Seo, Soon-Chun Jeong, Jai-Heon Lee, Youngsoo Chung, Ki-Hong Jung, Douglas R. Cook, Hong-kyu Choi
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091721
Abstract: Cross-species translation of genomic information may play a pivotal role in applying biological knowledge gained from relatively simple model system to other less studied, but related, genomes. The information of abiotic stress (ABS)-responsive genes in Arabidopsis was identified and translated into the legume model system, Medicago truncatula. Various data resources, such as TAIR/AtGI DB, expression profiles and literatures, were used to build a genome-wide list of ABS genes. tBlastX/BlastP similarity search tools and manual inspection of alignments were used to identify orthologous genes between the two genomes. A total of 1,377 genes were finally collected and classified into 18 functional criteria of gene ontology (GO). The data analysis according to the expression cues showed that there was substantial level of interaction among three major types (i.e., drought, salinity and cold stress) of abiotic stresses. In an attempt to translate the ABS genes between these two species, genomic locations for each gene were mapped using an in-house-developed comparative analysis platform. The comparative analysis revealed that fragmental colinearity, represented by only 37 synteny blocks, existed between Arabidopsis and M. truncatula. Based on the combination of E-value and alignment remarks, estimated translation rate was 60.2% for this cross-family translation. As a prelude of the functional comparative genomic approaches, in-silico gene network/interactome analyses were conducted to predict key components in the ABS responses, and one of the sub-networks was integrated with corresponding comparative map. The results demonstrated that core members of the sub-network were well aligned with previously reported ABS regulatory networks. Taken together, the results indicate that network-based integrative approaches of comparative and functional genomics are important to interpret and translate genomic information for complex traits such as abiotic stresses.
Temporal Variations on Soil Salinity and Cation Displacement at Saemangeum and Yeongsangang Reclaimed Tidal Lands  [PDF]
Sanghun Lee, Hui-Su Bae, Hong-Kyu Kim, Tae-Hwan Noh, Geon-Hwi Lee
Journal of Agricultural Chemistry and Environment (JACEN) , 2014, DOI: 10.4236/jacen.2014.34014
Abstract: Soil salinity at reclaimed tidal land in Korea is highly variable and depending on soil characteristics and weather conditions. The objective of this study was to evaluate the temporal changes on soil salinity and the relationships between soil salinity and salinity parameters in reclaimed tidal lands. Soil samples were periodically collected at 0 - 20 cm (surface) and 20 - 40 cm (subsurface) layer at Saemangeum (sandy loam) and Yeongsangang (silty loam) reclaimed tidal land. Electrical conductivity (EC) had a wide range from 0.0 to 34.3 dS·m-1 during the experimental period. The average soil EC was 6.4 and 3.4 dS·m-1 at Saemangeum and Yeongsangang reclaimed tidal land, respectively. Soluble sodium concentration had great variations and it was the most important single factor for temporal variations of soil EC regardless of soil textural properties. Calcium concentration was negatively correlated with soil EC and soluble sodium. Soil exchangeable sodium percentage (ESP) was estimated as a function of soil sodium adsorption ratio (SAR) and a linear regression model (ESP = 6.075 (SAR) + 0.677 for Saemangeum and ESP = 3.925 (SAR) + 0.421 for Yeongsangang reclaimed tidal soil) was suggested for predicting soil ESP from soil SAR. The characteristics of reclaimed tidal lands had different shares of saline and sodic properties during the experimental period. Saemangeum reclaimed tidal soil was highly characterized by sodium, but the effect of sodium on Yeongsangang soil was less pronounced. Our results indicate that persistent monitoring and modeling on soil salinity at reclaimed tidal soil is fundamental and the results can provide some useful information for deciding management plans for diverse utilization or to reduce salt damage for stable crop production at reclaimed tidal land.
Rotational properties of Maria asteroid family
Myung-Jin Kim,Young-Jun Choi,Hong-Kyu Moon,Yong-Ik Byun,Noah Brosch,Murat Kaplan,Suleyman Kaynar,Omer Uysal,Eda Guzel,Raoul Behrend,Joh-Na Yoon,Stefano Mottola,Stephan Hellmich,Tobias C. Hinse,Zeki Eker,Jang-Hyun Park
Physics , 2013, DOI: 10.1088/0004-6256/147/3/56
Abstract: Maria family is regarded as an old-type (~3 +/- 1 Gyr) asteroid family which has experienced substantial collisional and dynamical evolution in the Main-belt. It is located nearby the 3:1 Jupter mean motion resonance area that supplies Near-Earth asteroids (NEAs) to the inner Solar System. We carried out observations of Maria family asteroids during 134 nights from 2008 July to 2013 May, and derived synodic rotational periods for 51 objects, including newly obtained periods of 34 asteroids. We found that there is a significant excess of fast and slow rotators in observed rotation rate distribution. The two-sample Kolmogorov-Smirnov test confirms that the spin rate distribution is not consistent with a Maxwellian at a 92% confidence level. From correlations among rotational periods, amplitudes of lightcurves, and sizes, we conclude that the rotational properties of Maria family asteroids have been changed considerably by non-gravitational forces such as the YORP effect. Using a lightcurve inversion method (Kaasalainen & Torppa 2001; Kaasalainen et al. 2001), we successfully determined the pole orientations for 13 Maria members, and found an excess of prograde versus retrograde spins with a ratio (N_p/N_r) of 3. This implies that the retrograde rotators could have been ejected by the 3:1 resonance into the inner Solar System since the formation of Maria family. We estimate that approximately 37 to 75 Maria family asteroids larger than 1 km have entered the near-Earth space every 100 Myr.
Elevated Serum Ferritin Level Is Associated with the Incident Type 2 Diabetes in Healthy Korean Men: A 4 Year Longitudinal Study
Chang Hee Jung, Min Jung Lee, Jenie Yoonoo Hwang, Jung Eun Jang, Jaechan Leem, Joong-Yeol Park, JungBok Lee, Hong-Kyu Kim, Woo Je Lee
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0075250
Abstract: Background Elevated ferritin concentration has been implicated in the etiology of type 2 diabetes. Accumulating evidence, mostly from studies conducted on western populations, has demonstrated a strong association between the elevated ferritin concentrations and incident type 2 diabetes. In Asian populations, however, the longitudinal studies investigating the association of elevated serum ferritin levels and type 2 diabetes are lacking. In present study, we aimed to determine whether elevated serum ferritin levels are related to the incident type 2 diabetes in healthy Korean men. Methodology/Principal Findings This 4 year longitudinal observational study was conducted at the Asan Medical Center, Seoul, Republic of Korea. The study population consisted of 2,029 men without type 2 diabetes who underwent routine health examination in 2007 (baseline) and 2011 (follow-up). Baseline serum ferritin concentrations were measured by chemiluminescent two-site sandwich immunoassay. In multiple-adjusted model, the relative risk (RR) for incident type 2 diabetes was significantly higher in highest compared with the lowest ferritin quartile category, even after adjusting for confounding variables including homeostasis model assessment of insulin resistance (RR = 2.17, 95% confidence interval 1.27–3.72, P for trend = 0.013). Conclusions/Significance These results demonstrated that elevated level of serum ferritin at baseline was associated with incident type 2 diabetes in an Asian population.
DNA Microarray Analysis of Gene Expression in Eutopic Endometrium from Patients with Endometriosis  [PDF]
Kyu Ri Hwang, Young Min Choi, Jin Ju Kim, Hye Won Jeon, Min A. Hong
Advances in Reproductive Sciences (ARSci) , 2017, DOI: 10.4236/arsci.2017.54009
Abstract: Pathogenesis of the endometriosis is complex and the etiology is still unclear. The objective of this study was to examine that endometrial gene expression in late secretory phase endometrium differs between patients with and without endometriosis. Five patients with proven advanced-stage endometriosis and 5 controls underwent endometrial biopsy in the late secretory phase. Analysis of eutopic endometrial gene expression was performed using Affymetrix gene arrays and differentially expressed genes were assigned to gene ontology groups based on overrepresented analysis using Database for Annotation, Visualization, and Integrated Discovery software. Four hundred sixty two genes were identified as up-regulated such as matrix metalloproteinase 10, cytochrome P450 family 24 subfamily A polypeptide 1, matrix metalloproteinase 3, chemokine (C-C motif) ligand 20, Rho family GTPase 1, interleukin 1-beta, and insulin-like growth factor binding protein 1. Six hundred forty three genes were down-regulated in all endometriotic samples. A lot of genes related with metabolic process, cellular ketone metabolic process and ncRNA metabolic processing were included. Expression patterns of selected five genes were validated by quantitative real time PCR. The results of this analysis support that the eutopic endometrium from patients with advanced-stage endometriosis has distinct gene expression profile from eutopic endometrium of control without endometriosis.
Long-term effect of stereotactic body radiation therapy for primary hepatocellular carcinoma ineligible for local ablation therapy or surgical resection. Stereotactic radiotherapy for liver cancer
Jung Kwon, Si Bae, Ji Kim, Byung Choi, Hong Jang, Jeong Jang, Jong Choi, Seung Yoon, Kyu Chung
BMC Cancer , 2010, DOI: 10.1186/1471-2407-10-475
Abstract: Forty-two HCC patients with tumors ≤ 100 cc and ineligible for local ablation therapy or surgical resection were treated with SBRT: 30-39 Gy with a prescription isodose range of 70-85% (median 80%) was delivered daily in three fractions. Median tumor volume was 15.4 cc (3.0-81.8) and median follow-up duration 28.7 months (8.4-49.1).Complete response (CR) for the in-field lesion was initially achieved in 59.6% and partial response (PR) in 26.2% of patients. Hepatic out-of-field progression occurred in 18 patients (42.9%) and distant metastasis developed in 12 (28.6%) patients. Overall in-field CR and overall CR were achieved in 59.6% and 33.3%, respectively. Overall 1-year and 3-year survival rates were 92.9% and 58.6%, respectively. In-field progression-free survival at 1 and 3 years was 72.0% and 67.5%, respectively. Patients with smaller tumor had better in-field progression-free survival and overall survival rates (<32 cc vs. ≥32 cc, P < 0.05). No major toxicity was encountered but one patient died with extrahepatic metastasis and radiation-induced hepatic failure.SBRT is a promising noninvasive-treatment for small HCC that is ineligible for local treatment or surgical resection.Hepatocellular carcinoma (HCC) is one of the most common malignant diseases [1-3]. Of the current therapeutic approaches for HCC, surgical resection and liver transplantation are used with curative intent for patients with small HCC [4]. However, the majority of HCC patients are ineligible for surgery because most have a cirrhotic liver with poor liver function or tumors are located in the central segments. Several modalities including radiofrequency ablation (RFA) and percutaneous ethanol injection (PEI) have been used to treat small HCC, but the optimal treatment remains controversial particularly for cases of small HCC ineligible for curative therapy.Cyberknife (Accuracy Inc., Sunnyvale, CA) is a new stereotactic body radiation therapy (SBRT) that delivers a high dose of radiation in a
The C-terminal region of Bfl-1 sensitizes non-small cell lung cancer to gemcitabine-induced apoptosis by suppressing NF-κB activity and down-regulating Bfl-1
Min-Kyoung Kim, Yoon-Kyung Jeon, Jong-Kyu Woo, Yun Choi, Dae-Han Choi, Yeul-Hong Kim, Chul-Woo Kim
Molecular Cancer , 2011, DOI: 10.1186/1476-4598-10-98
Abstract: Lung cancer remains a leading cause of cancer-related death [1] despite the introduction of several types of cytotoxic agents. In non-small cell lung cancer (NSCLC), chemotherapy often achieves limited clinical improvements due to acquired drug resistance and intolerable toxicities. Gemcitabine (difluorodeoxycytidine hydrochloride, dFdC) is a deoxycytidine analogue that is converted in vivo into the active metabolites, difluorodeoxycytidine di- and triphosphate (dFdCDP, dFdCTP). DFdCDP acts by inhibiting ribonucleotide reductase, whereas dFdCTP is incorporated into DNA and prevents DNA synthesis, thereby inducing apoptosis. Gemcitabine has been approved by the Food and Drug Administration (FDA) as a treatment for advanced and metastatic pancreatic cancer, ovarian cancer, breast cancer, and NSCLC, alone or in combination with other drugs http://www.cancer.gov/cancertopics/druginfo/gemcitabinehydrochloride webcite. Clinical trials have demonstrated that gemcitabine prolongs survival and improves the quality of life of advanced NSCLC patients [2]. In fact, gemcitabine is considered to be one of the most effective agents for treating NSCLC. Previous studies have concluded that when used as a single agent, gemcitabine consistently yields response rates exceeding 20%. Furthermore, preclinical data indicate that when used with platinum compounds, such as, cisplatin or carboplatin, gemcitabine has synergistic anti-tumor effects [3,4].However, gemcitabine often fails to achieve adequate disease control due to intrinsic or acquired resistance of tumor cells. The following are representative examples of putative resistance mechanisms; NF-κB and PI3K/Akt pathway activation in pancreatic and breast cancer [5,6] the up-regulation of anti-apoptotic Bcl-2 protein in pancreatic cancer [7,8] the deficiency of human equilibrate nucleoside transporter 1 in NSCLC [9]and alterations of gemcitabine metabolizing enzymes [10-13]. Many of these chemo-resistant mechanisms involve interrupting
Prediction of the Bandgap of a Core-Shell Microsphere via Light Intensity Fluctuations
Moon Kyu Choi,Youngjin Choi
International Journal of Photoenergy , 2011, DOI: 10.1155/2011/679364
Abstract: It has been experimentally observed that in the case of microspheres irradiated by light, the absorption wavelength shift occurs, known as the blueshift, with changing shell materials (i.e., by decreasing the refractive index of the shell). In the present investigation, we want to demonstrate it numerically by using the boundary element method. The material used for the simulation is a core-shell (SiO2 and another material of a larger refractive index) microsphere and it is irradiated by unpolarized monochromatic light wave. This paper intends to demonstrate that it is possible to predict the bandgap of a core-shell microsphere resulting from two different bandgap materials and that the numerical simulation employed produces the blueshift. 1. Introduction There are many different methods to produce semiconductor nanocrystals and consequently they will have different optical and structural properties depending on how they are produced. Above all, one is interested in the bandgap of the newly synthesized material because it is directly related to light absorption and luminescence wavelength. Primarily of interest is the realization of the wavelength range for nanocrystal-based green LEDs and white-light generation. One of the exciting examples is alloy nanocrystals because the luminescence wavelength from them may be tuned by changing the composition (Cd?:?Zn) without changing the nanocrystal size [1, 2]. Depending on the production methods, the filmed materials will have different optical and structural properties including bandgaps. One of the most desirable abilities that we want to have regarding the design of thin film electronic devices is to predict the bandgap magnitude of the coated devices, given the bandgaps of each material. A key factor for the development of photonic integrated circuits (PICs) is its ability to selectively control the bandgap across a semiconductor wafer. Since the semiconductor bandgap can be easily controlled during the growth, the use of selective epitaxial growth, or etching and regrowth, has been extensively studied for different semiconductor platforms. Quantum well intermixing (QWI) is a well-known method for the postgrowth modification in QW heterostructures eliminating the need for epitaxial regrowth. A phenomenon showing light-matter interaction is the photonic confinement in a small dimension which sets the vacuum electric field amplitude of the cavity photons. Another way to explain this phenomenon is that one can interpret the intensity fluctuations as the cause of energy conversion according to the
Electromagnetic Characteristics of a Superconducting Magnet for 28GHz ECR Ion Source according to the Series Resistance of a Protection Circuit
Hongseok Lee,Young Kyu Mo,Onyou Lee,Junil Kim,Seungmin Bang,Jong O Kang,Jonggi Hong,Seokho Nam,Sukjin Choi,In Seok Hong,Min Chul Ahn,Hyoungku Kang
Physics , 2015,
Abstract: A linear accelerator, called RAON, has been being developed as a part of Rare Isotope Science Project (RISP) by Institute for Basic Science (IBS) [1]. The linear accelerator utilizes an electron cyclotron resonance (ECR) ion source for providing intense highly charged ion beams to the linear accelerator. 28GHz ECR ion source can extract heavy ion beams from proton to uranium. A superconducting magnet system for 28GHz ECR ion source is composed of hexapole coils and four solenoid coils made with low Tc superconducting wires of NbTi [2]. The electromagnetic force acts on the superconducting magnets due to the magnetic field and flowing current in case of not only normal state but also quench state [3]. In case of quench on hexapole coils, unbalanced flowing current among the hexapole coils is generated and it causes unbalanced electromagnetic force. Coil motions and coil strains in quench state are larger than those in normal state due to unbalanced electromagnetic force among hexapole coils. Therefore, analysis on electromagnetic characteristics of superconducting magnet for 28GHz ECR ion source according to the series resistance of protection circuit in case of quench should be conducted. In this paper, analysis on electromagnetic characteristics of superconducting hexapole coils for 28GHz ECR ion source according to the series resistance of protection circuit in case of quench is performed by using finite elements method (FEM) simulation.
Application of tissue engineering in stem cell therapy  [PDF]
Jong Kyu Hong, Sang Mo Kwon
Journal of Biomedical Science and Engineering (JBiSE) , 2014, DOI: 10.4236/jbise.2014.72010
Abstract: Tissue engineering based on stem cells has gained interest recently as attempts are made to engineer scaffold environments mimicking the stem cell niche, which contains a reservoir of multipotent stem cells that can maintain normal tissue or restore unhealthy cell populations in response to mechanisms of quiescence, self-renewal, and differentiation of the stem cells. These cell behaviors are governed by soluble signals that are systemic or presented by local niche cells. In this review, current and emergent approaches based on stem cells in the field of tissue engineering are presented for specific applications of human tissues and organs. The combination of stem cells and tissue engineering opens new perspectives in tissue regeneration for stem cell therapy because of the potential to control stem cell behavior with the physical and chemical characteristics of the engineered scaffold environment.
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