• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.8
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• pp.724-728
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• 2005

Electro-optic characteristics of reflective hybrid aligned liquid crystal (LC) cell driven by fringe field using a nematic LC with positive dielectric anisotropy have been studied. Optimized optical configurations are achieved by using a single polarizer, half-wave film and a cell with quarter-wave retardation. The simulation results shows an optimum cell retardation of $0.30{\mu}m$. This value may allow a practical cell gap larger than $3{\mu}m$, which makes it easy to control in the manufacturing process. Furthermore, this LC cell with optimized cell parameters shows low wavelength dispersion and the contrast ratio greater than 5 over exists about $100{\circ}$ in vertical direction and $160{\circ}$ in horizontal direction. Also, when using the LC with positive dielectric anisotropy rather than negative dielectric anisotropy, the display shows low power consumption and fast response time.

• The Journal of the Acoustical Society of Korea
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• v.15 no.5
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• pp.13-20
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• 1996

Recently, for implementation of neural networks extensive studies have been done especially VLSI technology has been regarded as the one of the most attractive means to implement neural networks. The main drawbacks of digital VLSI implementations are their large area and slow processing speed. In this paper to solve the speed and size problems we designed the efficient architecture using the binary convolution method for basic operation of neural cell, multiplication and addition. When it is used for implementing 3-layer network with 16 neural cell per layer that used neural cell based on binary convolution, clock of 50MHz and 26MCPS on 0.8${\mu}$ standard cell library has been achieved.

• Biomedical Science Letters
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• v.11 no.3
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• pp.337-341
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• 2005

This study was undertaken to clerify the cytotoxic effect of syringic acid by colorimetric assay on human cancer cells. For the evaluation of cytotoxicity of syringic acid, the cell viability and cell adhesion activity of syringic acid on cancer cells, human oral epithelioid carcinoma cells were determined using by colorimetric assays such as MTT (3-[4,5­dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay and XTT (2,3-bis-[2-methoxy-4-nitro-5-sulfophenyl]­2H-tetrazolium-5-caboxanilide) assay, respectively after human oral epithelioid carcinoma cells were treated with syringic acid for 48 hours. In this study, the cell viability of syringic acid on human oral epithelioid carcinoma cells showed a significant decrease by MTT assay compared with control, and also, the cell adhesion activity by XTT assay was decreased significantly in these cells after cells were treated with various concentrations of syringic acid for 48 hours. $MTT_{50}\;and\;XTT_{50}\;were\;282.3\;{\mu}M\;and\;418.8{\mu}M$ syringic acid, respectively. These results suggest that syringic acid shows midcytotoxic effect on human oral epithelioid carcinoma cells by the decreasement of the cell viability and the cell adehision activity assessed by colorimetric assay in these cultures.

• Journal of Pharmaceutical Investigation
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• v.40 no.6
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• pp.333-337
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• 2010

Combining cell- and gene-based therapy is a promising therapeutic strategy in regenerative medicine. The aim of this study was to develop genetically modified mesenchymal stem cell (MSC) aggregates using a poly(ethylene glycol) (PEG) hydrogel micro-well array technique. Stable PEG hydrogel micro-well arrays with diameters of 200 to $500\;{\mu}m$ were fabricated and used to generate genetically engineered MSC aggregates. Rat bone marrow-derived MSCs were transfected with a green fluorescent protein (GFP) plasmid as a reporter gene, and aggregated by culturing in the PEG hydrogel micro-well arrays. The resultant cell aggregates had a mean diameter of less than $200\;{\mu}m$, and maintained the mesenchymal phenotype even after genetic modification and cell aggregation. Transplantation of MSC aggregates that are genetically modified to express therapeutic or cell-survival genes may be a potential therapeutic approach for regenerative medicine.

• Journal of Society of Preventive Korean Medicine
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• v.13 no.2
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• pp.39-50
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• 2009

Objectives : In order to evaluate the cytotoxicity of 3,4,5-trihydroxybenzoic acid and related compounds on the growth of normal cell lines and human oral epithelioid cell line, cell viability, cell adhesion ability, and morphological changes of cells were examined. Methods : We measured the cytotoxicity of 3,4,5-trihydroxybenzoic acid and related compounds with 3-[4,5-dimethyl-thiazol-2-yl]-2,5-diphenyltetrazolium bromide-[MTT), and 2,3-bis-[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium -5-caboxanilide-[XTT) methods. Results : The cytotoxicity of 3,4,5-trihydroxybenzoic acid($IC_{50}$, $2,552.40\;{\mu}M$) was low according to the toxic criteria. Cytotoxic effect of 3,4,5-trihydroxybenzoic acid and related compounds against $IC_{50}$ value in cell morphology increased in a concentration-dependent manner. In light microscopy, $100\;{\mu}M$ 3,4,5-trihydroxy-benzoic acid showed th highest cytotoxic activity. Conclusions : These results suggest that 3,4,5-trihydroxybenzoic acid may have a potential anticancer activity.

• Archives of Pharmacal Research
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• v.27 no.4
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• pp.402-406
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• 2004

This research team found in previous studies, that the ginseng saponin metabolite IH901 induces apoptosis in HepG2 cells via a mitochondrial-mediated pathway, which resulted in the activation of caspase-9 and subsequently of caspase-3 and -8. Based on these results, the involvement of the Fas/Fas ligand (FasL) death-receptor pathway, in IH901-induced apoptosis in HepG2 cells, was investigated. Levels of Fas and the Fas ligand (FasL) mRNA or protein were not increased by IH901, rather they were decreased significantly at 18 h post treatment. Soluble FasL (sFasL) was detectable by immunoprecipitation analysis En the medium of HepG2 cells treated with IH901. Increased levels of sFasL were inversely correlated with the levels of FasL. Preincubation of HepG2 cells with antagonistic anti-Fas antibody showed little protective effect, if any, on IH901-induced cell death. At a $30{\mu}M$ (24 and 48 h) and $40{\mu}M$ (24 h) concentration of IH901, the cytotoxic effect of IH901 was less then $50\%$, anti-Fas antibody prevented IH901-induced cell death. However, at a $60{\mu}M$ (24 and 48 h) and $40{\mu}M$ (48 h) concentration of IH901, cell death rates were about $80\%$ or more and most of the chemopreventive and chemotherapeutic effects of IH901 were manifested. Blocking the Fas receptor did not influence IH901-induced cell death. These results indicate that the Fas/FasL system is engaged, but not required for IH901-induced cell death, at pharmacologically significant concentrations.

• Preventive Nutrition and Food Science
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• v.16 no.2
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• pp.174-178
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• 2011

The cell permeability and cytotoxic effects of different-sized zinc oxide (ZnO) particles were investigated using a human colorectal adenocarcinoma cell line called Caco-2. Morphological observation by scanning electron microscopy revealed that three zinc oxides with different mean particle sizes (ZnO-1, 20 nm; ZnO-2, 90~200 nm; ZnO-3, $1\sim5\;{\mu}m$) tended to aggregate, particularly in the case of ZnO-1. When cytotoxicities of all three sizes of zinc oxide particles were measured at concentration ranges of $1\sim1000\;{\mu}g$/mL, significant decreases in cell viability were observed at concentrations of $50\;{\mu}g$/mL and higher. Among the three zinc oxides, ZnO-1 showed the lowest viability at $50\;{\mu}g$/mL in Caco-2 cells, followed by ZnO-2 and ZnO-3. The permeate concentration of ZnO-1 from the apical to the basolateral side in the Caco-2 model system after four hours was about three-fold higher than that of either ZnO-2 or ZnO-3. These results demonstrated that ZnO-1, with a 20 nm mean particle size, had poorer viability and better permeability in Caco-2 cells than ZnO-2 and ZnO-3.

• The Journal of the Korean dental association
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• v.46 no.9
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• pp.563-573
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• 2008

Purpose : The purpose of this study is to investigate the effects of Simvastain, which is HMG-CoA reductase inhibitor, on proliferation and differentiation of osteoblast. Materials & Methods : Twenty-four cell culture plates containing essential medium were seeded with UMR-106 cell lines, at density of 5 x $10^4$ cells per plate. Each plates were incubated with 5% $CO^2$incubator $37^{\circ}C$. Starting from 2 days after incubation, cell culture medias were replaced with Osteogenesis induction media every 2 days, for 12 days. In some plates, 0.01, 0.1, 1, 10, $100\muM$ of Simvastatin were added with Osteogenesis induction media, and classified as "test group". Those not added with Simvastatin were classified as "control group". Results : 1. When Alrizarin Red staining was observed with naked eye, control group showed normal deep red color, but test group show rapid decrease of red color as Simvastatin concentration increased more than $0.1\muM$. 2, When observed with microscope, compared to control group, amount of osteo matrix stained with Alrizarin Red decreased rapidly in Simvastatin concentration more than $0.1\muM$. 3. In optical density analysis, regarding control group as a basis, mineral deposition decreased rapidly when Simvastatin concentration increased more than $0.1\muM$. 4. In flow cytometry analysis, survival rate of UMR-106 cell showed no changes in both control group and test group. Conclusion : From the above results, we were able to identify that Simvastatin inhibited osteogenesis without effecting survival or cell number of osteoblasts.

• Journal of Periodontal and Implant Science
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• v.34 no.2
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• pp.357-366
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• 2004

Chronic exposure to high levels of manganese leads a pronounce and debilitating disorder known as manganism. Research on the toxic manifestation of manganese have focused primarily on its neurological effects because exposure to high levels of the metal produces a distinct and irreversible extrapyramidal dysfunction resembling the dystonic movements associated with Parkinson's physiological and biochemical systems in the body. The purpose of this study was to evaluate the effect of manganeses on primary rat calvarial cell growth and toxicity. The experimental groups were in concentration of 0, 10, 30, 60, 100, 300 ${\mu}M$. Cell activity was assessed at day 1 and day 3 using a fluorescent molecular probe. Cell proliferation was evaluated at day 1 and day 3 by MTT assay. The amount of total protein synthesis was measured at day 3 and day 7. The results were as follows: The proliferation of primary rat calvarial cells were inhibited by $MnCl_2$ in the concentration exceeding $100{\mu}M$. The primary rat calvarial cells treated with $MnCl_2$ showed similar protein synthesis to the control group except in 100 ${\mu}M$. These result suggest that manganese suppress the viability and protein synthesis of primary rat calvarial cells in concentration exceeding $100{\mu}M$.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.4
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• pp.1505-1510
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• 2012

To aim of this was to observe emodin-mediated cytotoxicity and its influence on Rad51 and ERCC1 expressionin non-small cell lung cancer (NSCLC). NSCLC cells were cultured in vitro with emodin at various concentrations (0, 25, 50, 75 and $100\;{\mu}mol/L$) for 48h and the proliferation inhibition rate was determined by the MTT method. Then, NSCLC were treated with emodin (SK-MES-1 $40\;{\mu}mol/L$, A549 $70\;{\mu}mol/L$) or $20\;{\mu}mol/L$ U0126 (an ERK inhibitor) for 48 h, or with various concentrations of emodin for 48 h and the protein and mRNA expressions of ERCC1 and Rad51 were determined by RT-PCR and Western blot assay, respectively. Emodin exerted a suppressive effect on the proliferation of NSCLC in a concentration dependent manner. Protein and mRNA expression of ERCC1 and Rad51 was also significantly decreased with the dose. Vacuolar degeneration was observed in A549 and SK-MES-1 cell lines after emodin treatment by transmission electron microscopy. Emodin may thus inhibited cell proliferation in NSCLC cells by downregulation ERCC1 and Rad51.