oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 28 )

2018 ( 72 )

2017 ( 73 )

2016 ( 97 )

Custom range...

Search Results: 1 - 10 of 28221 matches for " Kyung-jong Lee "
All listed articles are free for downloading (OA Articles)
Page 1 /28221
Display every page Item
A Sensitive and Quantitative Polymerase Chain Reaction-Based Cell Free In Vitro Non-Homologous End Joining Assay for Hematopoietic Stem Cells
Lijian Shao, Wei Feng, Kyung-Jong Lee, Benjamin P. C. Chen, Daohong Zhou
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033499
Abstract: Hematopoietic stem cells (HSCs) are responsible for sustaining hematopoietic homeostasis and regeneration after injury for the entire lifespan of an organism. Maintenance of genomic stability is crucial for the preservation of HSCs, which depends on their efficient repair of DNA damage, particularly DNA double strand breaks (DSBs). Because of the paucity of HSCs and lack of sensitive assays, directly measuring the ability of HSCs to repair DSBs has been difficult. Therefore, we developed a sensitive and quantitative cell free in vitro non-homologous end joining (NHEJ) assay using linearized plasmids as the substrates and quantitative polymerase chain reaction (qPCR) technique. This assay can sensitively detect DSB repair via NHEJ in less than 1 μg 293T cell nuclear proteins or nuclear extracts from about 5,000 to 10,000 human BM CD34+ hematopoietic cells. Using this assay, we confirmed that human bone marrow HSCs (CD34+CD38? cells) are less proficient in the repair of DSBs by NHEJ than HPCs (CD34+CD38+ cells). In contrast, mouse quiescent HSCs (Pyronin-Ylow LKS+ cells) and cycling HSCs (Pyronin-Yhi LKS+ cells) repaired the damage more efficiently than HPCs (LKS? cells). The difference in the abilities of human and mouse HSCs and HPCs to repair DSBs through NHEJ is likely attributed to their differential expression of key NHEJ DNA damage repair genes such as LIG4. These findings suggest that the qPCR-based cell free in vitro NHEJ assay can be used to sensitively measure the ability of human and mouse HSCs to repair DSBs.
Epigenetic mechanisms involved in differential MDR1 mRNA expression between gastric and colon cancer cell lines and rationales for clinical chemotherapy
Tae-Bum Lee, Jung-Hee Park, Young-Don Min, Kyung-Jong Kim, Cheol-Hee Choi
BMC Gastroenterology , 2008, DOI: 10.1186/1471-230x-8-33
Abstract: The MDR1 mRNA levels were determined using PCR and real-time PCR assays after reverse transcription. Cytotoxicity was performed using the MTT assay. Methylation status was explored by quantification PCR-based methylation and bisulfite DNA sequencing analyses.The MDR1 mRNA levels obtained by 35 cycles of RT-PCR in gastric cancer cells were just comparable to those obtained by 22 cycles of RT-PCR in colon cancer cells. Real-time RT-PCR analysis revealed that MDR1 mRNA was not detected in the 10 gastric cancer cell lines but variable MDR1 mRNA levels in 7 of 9 colon cancer cell lines except the SNU-C5 and HT-29 cells. MTT assay showed that Pgp inhibitors such as cyclosporine A, verapamil and PSC833 sensitized Colo320HSR (colon, highest MDR1 expression) but not SNU-668 (gastric, highest) and SNU-C5 (gastric, no expression) to paclitaxel. Quantification PCR-based methylation analysis revealed that 90% of gastric cancer cells, and 33% of colon cancer cells were methylated, which were completely matched with the results obtained by bisulfite DNA sequencing analysis. 5-aza-2'-deoxcytidine (5AC, a DNA methyltransferase inhibitor) increased the MDR1 mRNA levels in 60% of gastric cells, and in 11% of colon cancer cells. Trichostatin A (TSA, histone deacetylase inhibitor) increased the MDR1 mRNA levels in 70% of gastric cancer cells and 55% of colon cancer cells. The combined treatment of 5AC with TSA increased the MDR1 mRNA levels additively in 20% of gastric cancer cells, but synergistically in 40% of gastric and 11% of colon cancer cells.These results indicate that the MDR1 mRNA levels in gastric cancer cells are significantly lower than those in colon cancer cells, which is at least in part due to different epigenetic regulations such as DNA methylation and/or histone deacetylation. These results can provide a better understanding of the efficacy of combined chemotherapy as well as their oral bioavailability.Gastric and colorectal cancers are a cause of morbidity and mortal
Social Engagement, Health, and Changes in Occupational Status: Analysis of the Korean Longitudinal Study of Ageing (KLoSA)
Jin-young Min, Kyung-jong Lee, Jae-beom Park, Sung-il Cho, Shin-goo Park, Kyoungbok Min
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0046500
Abstract: Background We focused on whether changes in the occupational status of older male adults can be influenced by social engagement and health status measured at the baseline. Methods This study used a sample of the Korean Longitudinal Study of Aging (KLoSA), and the study population was restricted to 1.531 men who were aged 55 to 80 years at the 2006 baseline survey and participated in the second survey in 2008. Social engagement and health status, measured by the number of chronic diseases, grip strength, and depressive symptoms as well as covariates (age, marital status, educational level, and household income) were based on data from the 2006 baseline survey. Occupational engagement over the first and second survey was divided into four categories: ‘consistently employed’ (n = 892), ‘employed-unemployed’ (n = 152), ‘unemployed-employed’ (n = 138), and ‘consistently unemployed’ (n = 349). Results In the multinomial model, the ‘consistently employed’ and ‘unemployed-employed’ groups had significantly higher social engagement (1.19 and 1.32 times, respectively) than the referent. The number of chronic diseases was significantly associated with four occupational changes, and the ‘unemployed-employed’ had the fewest chronic conditions. Conclusion Our finding suggests that social engagement and health status are likely to affect opportunities to continue working or to start working for older male adults.
Molecular mechanisms of heptaplatin effective against cisplatin-resistant cancer cell lines: less involvement of metallothionein
Cheol-Hee Choi, Yoon-Jung Cha, Chun-San An, Kyung-Jong Kim, Kweon-Cheon Kim, Sung-Pyo Moon, Zang Lee, Young-Don Min
Cancer Cell International , 2004, DOI: 10.1186/1475-2867-4-6
Abstract: Molecular mechanisms of heptaplatin effective against cisplatin-resistant cancer cell lines has been investigated in connection with metallothionein (MT). Cytotoxicity was determined by an MTT assay. MT mRNA, was determined by RT-PCR assay. Transfection study was carried out to examine the function of MT.Of various gastric cancer cell lines, SNU-638 and SNU-601 showed the highest and lowest levels of MT mRNA, respectively, showing 80-fold difference. The IC50 values of SNU-638 to cisplatin, carboplatin and heptaplatin were 11.2-fold, 5.1-fold and 2.0-fold greater than those of SNU-601, respectively. Heptaplatin was more effective against cisplatin-resistant and MT-transfected gastric cancer sublines than cisplatin or carboplatin was. In addition, heptaplatin attenuated cadmium, but not zinc, induction of MT.These results indicate that molecular mechanisms of heptaplatin effective against cisplatin-resistant gastric cancer sublines is at least in part due to the less involvement of MT in heptaplatin resistance as well as its attenuation of MT induction.Gastric cancer is the most frequently diagnosed and the second leading cause of cancer-related death in Korea. For many years, a few single agents such as 5-fluorouracil, doxorubicin, mitomycin C, and nitrosourea, have been considered to have significant antitumor activity in gastric cancer patients [1]. However, the response rate has been <30% and complete remission has been rare. Several combination chemotherapy regimens such as FAM (5-fluorouracil, adriamycin, and mitomycin C) have been attempted in order to improve the treatment outcomes. In a nonrandomized Phase II study for advanced gastric cancer, the FAM regimen achieved an objective partial response rate of 42% [2]. Some cisplatin-based combination chemotherapy regimens have shown high response rates [3,4].Despite the efficacy of cisplatin against gastric cancer, there were two major problems with this agent. Firstly, there are significant side effects, such a
Does phosphorylation of cofilin affect the progression of human bladder cancer?
Chung Hong,Kim Bokyung,Jung Seung-Hyo,Won Kyung-Jong
BMC Cancer , 2013, DOI: 10.1186/1471-2407-13-45
Abstract: Background We determined the differently expressed protein profiles and their functions in bladder cancer tissues with the aim of identifying possible target proteins and underlying molecular mechanisms for taking part in their progression. Methods We examined the expression of proteins by proteomic analysis and western blot in normal urothelium, non-muscle-invasive bladder cancers (NMIBCs), and muscle-invasive bladder cancers (MIBCs). The function of cofilin was analyzed using T24 human bladder cancer cells. Results The expression levels of 12 proteins were altered between bladder cancers and normal bladder tissues. Of these proteins, 14-3-3σ was upregulated in both NMIBCs and MIBCs compared with controls. On the other hand, myosin regulatory light chain 2, galectin-1, lipid-binding AI, annexin V, transthyretin, CARD-inhibitor of NF-κB-activating ligand, and actin prepeptide were downregulated in cancer samples. Cofilin, an actin-depolymerizing factor, was prominent in both NMIBCs and MIBCs compared with normal bladder tissues. Furthermore, we confirmed that cofilin phosphorylation was more prominent in MIBCs than in NMIBCs using immunoblotting and immunohistochemcal analyses. Epidermal growth factor (EGF) increased the phosphorylation of cofilin and elevated the migration in T24 cells. Knockdown of cofilin expression with small interfering RNA attenuated the T24 cell migration in response to EGF. Conclusions These results demonstrate that the increased expression and phosphorylation of cofilin might play a role in the occurrence and invasiveness of bladder cancer. We suspected that changes in cofilin expression may participate in the progression of the bladder cancer.
Photoelectrochemical Properties of Supported on -Based Thin Films Converted from Self-Assembled Hydrogen Titanate Nanotube Powders
Kyung-Jong Noh,Hyo-Jin Oh,Bo-Ra Kim,Sang-Chul Jung,Wooseung Kang,Sun-Jae Kim
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/475430
Abstract: A photoanode was fabricated using hematite (α-Fe2O3) nanoparticles which had been held in a thin film of hydrogen titanate nanotubes (H-TiNT), synthesized by repetitive self-assembling method on FTO (fluorine-doped tin oxide) glass, which were incorporated via dipping process in aqueous Fe(NO3)3 solution. Current voltage (I-V) electrochemical properties of the photoanode heat-treated at 500°C for 10 min in air were evaluated under ultraviolet-visible light irradiation. Microstructure and crystallinity changes were also investigated. The prepared Fe2O3/H-TiNT/FTO composite thin film exhibited about threefold as much photocurrent as the Fe2O3/FTO film. The improvement in photocurrent was considered to be caused by reduced recombination of electrons and holes, with an appropriate amount of Fe2O3 spherical nanoparticles supported on the H-TiNT/FTO film. Nanosized spherical Fe2O3 particles with about 65 wt% on the H-TiNT/FTO film showed best performance in our study.
Biodiesel Resistance of Thin Resin Cr-Free Steel Sheets for Fuel Tank  [PDF]
Dong-Joo Yoon, Kyung-Hwan Lee, Jong-Geun Choi, Sangkeol Noh, Jongsang Kim
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.35057
Abstract: The content of biodiesel mixed with diesel fuel were compared to inspect the fuel resistance of thin resin Cr-free steel sheets, which are widely used as steel sheets of automobile fuel tank. Some additives which can be presented during the process of biodiesel preparation were added for CCT (Cyclic Corrosion Test). These additives can accelerate the occurrence of corrosion. The corrosion was appeared on the coating and painting layer and in serious cases even substrate material was corroded. For methanol, mixing with blended fuel showed the reduction in corroded area as the additive concentration was reduced in the mixed fuel. Especially the peroxide hydrogen showed the strongest corrosiveness. It is known that formic acid has a tendency of weaker corrosiveness than peroxide hydrogen, but the corrosion is occurred throughout the specimen. Water is not mixed well with fuel, and does not seem to impact on corrosion significantly. However, water is easily mixed with other additives and is considered to facilitate the corrosion by other additives.
The genome-scale metabolic network analysis of Zymomonas mobilis ZM4 explains physiological features and suggests ethanol and succinic acid production strategies
Kyung Lee, Jong Park, Tae Kim, Hongseok Yun, Sang Lee
Microbial Cell Factories , 2010, DOI: 10.1186/1475-2859-9-94
Abstract: The genome-scale metabolic model of Z. mobilis ZM4, ZmoMBEL601, was reconstructed based on its annotated genes, literature, physiological and biochemical databases. The metabolic model comprises 579 metabolites and 601 metabolic reactions (571 biochemical conversion and 30 transport reactions), built upon extensive search of existing knowledge. Physiological features of Z. mobilis were then examined using constraints-based flux analysis in detail as follows. First, the physiological changes of Z. mobilis as it shifts from anaerobic to aerobic environments (i.e. aerobic shift) were investigated. Then the intensities of flux-sum, which is the cluster of either all ingoing or outgoing fluxes through a metabolite, and the maximum in silico yields of ethanol for Z. mobilis and Escherichia coli were compared and analyzed. Furthermore, the substrate utilization range of Z. mobilis was expanded to include pentose sugar metabolism by introducing metabolic pathways to allow Z. mobilis to utilize pentose sugars. Finally, double gene knock-out simulations were performed to design a strategy for efficiently producing succinic acid as another example of application of the genome-scale metabolic model of Z. mobilis.The genome-scale metabolic model reconstructed in this study was able to successfully represent the metabolic characteristics of Z. mobilis under various conditions as validated by experiments and literature information. This reconstructed metabolic model will allow better understanding of Z. mobilis metabolism and consequently designing metabolic engineering strategies for various biotechnological applications.The impact of biotechnology on industry and society is dramatically gaining momentum, particularly in the field of agriculture-food, medicine and chemical production. For the chemical industry, which aims to producing value-added chemicals and fuels in a sustainable way, efforts have been put into strain improvement of microorganisms, utilizing many newly emergin
Genetic and Epigenetic Alterations of the NF2 Gene in Sporadic Vestibular Schwannomas
Jong Dae Lee, Tae Jun Kwon, Un-Kyung Kim, Won-Sang Lee
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0030418
Abstract: Background Mutations in the neurofibromatosis type 2 (NF2) tumor-suppressor gene have been identified in not only NF2-related tumors but also sporadic vestibular schwannomas (VS). This study investigated the genetic and epigenetic alterations in tumors and blood from 30 Korean patients with sporadic VS and correlated these alterations with tumor behavior. Methodology/Principal Findings NF2 gene mutations were detected using PCR and direct DNA sequencing and three highly polymorphic microsatellite DNA markers were used to assess the loss of heterozygosity (LOH) from chromosome 22. Aberrant hypermethylation of the CpG island of the NF2 gene was also analyzed. The tumor size, the clinical growth index, and the proliferative activity assessed using the Ki-67 labeling index were evaluated. We found 18 mutations in 16 cases of 30 schwannomas (53%). The mutations included eight frameshift mutations, seven nonsense mutations, one in-frame deletion, one splicing donor site, and one missense mutation. Nine patients (30%) showed allelic loss. No patient had aberrant hypermethylation of the NF2 gene and correlation between NF2 genetic alterations and tumor behavior was not observed in this study. Conclusions/Significance The molecular genetic changes in sporadic VS identified here included mutations and allelic loss, but no aberrant hypermethylation of the NF2 gene was detected. In addition, no clear genotype/phenotype correlation was identified. Therefore, it is likely that other factors contribute to tumor formation and growth.
Antagonist Effects of Veratric Acid against UVB-Induced Cell Damages
Seoung Woo Shin,Eunsun Jung,Seungbeom Kim,Kyung-Eun Lee,Jong-Kyung Youm,Deokhoon Park
Molecules , 2013, DOI: 10.3390/molecules18055405
Abstract: Ultraviolet (UV) radiation induces DNA damage, oxidative stress, and inflammatory processes in human epidermis, resulting in inflammation, photoaging, and photocarcinogenesis. Adequate protection of skin against the harmful effect of UV irradiation is essential. In recent years naturally occurring herbal compounds such as phenolic acids, flavonoids, and high molecular weight polyphenols have gained considerable attention as beneficial protective agents. The simple phenolic veratric acid (VA, 3,4-dimethoxybenzoic acid) is one of the major benzoic acid derivatives from vegetables and fruits and it also occurs naturally in medicinal mushrooms which have been reported to have anti-inflammatory and anti-oxidant activities. However, it has rarely been applied in skin care. This study, therefore, aimed to explore the possible roles of veratric acid in protection against UVB-induced damage in HaCaT cells. Results showed that veratric acid can attenuate cyclobutane pyrimidine dimers (CPDs) formation, glutathione (GSH) depletion and apoptosis induced by UVB. Furthermore, veratric acid had inhibitory effects on the UVB-induced release of the inflammatory mediators such as IL-6 and prostaglandin-E2. We also confirmed the safety and clinical efficacy of veratric acid on human skin. Overall, results demonstrated significant benefits of veratric acid on the protection of keratinocyte against UVB-induced injuries and suggested its potential use in skin photoprotection.
Page 1 /28221
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.