• BMB Reports
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• v.35 no.3
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• pp.297-301
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• 2002

Membrane lipid peroxidation processes yield products that may react with DNA and proteins to cause oxidative modifications. The oxyR gene product regulates the expression of enzymes and proteins that are needed for cellular protection against oxidative stress. Upon exposure to tert-butylhydroperoxide (t-BOOH) and 2,2'-azobis (2-amidinopropane) hydrochloride (AAPH), which induce lipid peroxidation in membranes, the Escherichia coli oxyR overexpression mutant was much more resistant to lipid peroxidation-mediated cellular damage, when compared to the oxyR deletion mutant in regard to growth kinetics, viability, and DNA damage. The deletion of the oxyR gene in E. coli also resulted in increased susceptibility of superoxide dismutase to lipid peroxidation-mediated inactivation. The results indicate that the peroxidation of lipid is probably one of the important intermediary events in free radical-induced cellular damage. Also, the oxyR regulon plays an important protective role in lipid peroxidation-mediated cellular damage.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.936-941
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• 2004

In recent years, the rapid growth of portable electronic devices requires the high-energy density characteristics of batteries. Zinc air batteries have specific capacity as high as 820mAh/g. However, Zinc air batteries used for hearing aid applications only so far, because the atmosphere could affect it, and it has weakness in the rate capability. However, recent developments of electrode manufacturing technologies made us to overcome that weakness. And the efforts of applying zinc air batteries to portable electronic devices, especially in cellular phone application have been increased. In this paper, the effects of conducting material and polymer binder in cathode on the electrochemical characteristics were investigated. Our research team succeeded in producing 2.4Ah class zinc air battery for cellular phone application. Its volumetric energy density was 920 wh/l, and gravimetric energy density was 308 wh/kg. The volumetric energy density of our zinc air battery is two times higher than one of lithium secondary battery, and three times higher than that of alkaline manganese battery.

• Corrosion Science and Technology
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• v.16 no.2
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• pp.64-68
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• 2017

The interactions between corrosion pits on stainless steel under loading conditions are studied by using a cellular automata model coupled with finite element method at a mesoscopic scale. The cellular automata model focuses on a metal/film/electrolyte system, including anodic dissolution, passivation, diffusion of hydrogen ions and salt film hydrolysis. The Chopard block algorithm is used to improve the diffusion simulation efficiency. The finite element method is used to calculate the stress concentration on the pit surface during pit growth, and the effect of local stress and strain on anodic current is obtained by using the Gutman model, which is used as the boundary conditions of the cellular automata model. The transient current characteristics of the interactions between corrosion pits under different simulation factors including the breakdown of the passive film at the pit mouth and the diffusion of hydrogen ions are analyzed. The analysis of the pit stability product shows that the simulation results are close to the experimental conclusions.

• YAKHAK HOEJI
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• v.32 no.5
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• pp.313-318
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• 1988

Radioprotective ginseng protein fraction was isolated from Korean white ginseng and its cytotoxic effect on CHO-K1 cells was studied by the method of measuring the relative cell survival and total cellular protein content (FRAME method). When ginseng protein at the dose of 300, 600, 900, $1200{\mu}g/ml$ was treated to cells for 24 hrs, the relative survival was significantly decreased at the concentration of above $600{\mu}g/ml$, indicating the presence of cytotoxic effect of the protein at certain concentration. When cellular protein content was measured after ginseng protein at the dose of 300, 600, 900, $1200\;{\mu}g/ml$ was treated, the amount of cellular protein was significantly reduced at the concentration above $600{\mu}g/ml$ in the case of 24 hr treatment and at all concentrations including $300{\mu}g/ml$ in the case of 72 hr treatment. The data suggest that the protein may inhibit cell growth, resulting in the reduction of live cells in culture. $ID_{50}$ value which is the concentration of ginseng protein that reduces the total cellular protein content to 50% of the control was calculated as 2276.86 and $1323.32\;{\mu}g/ml$ in groups treated for 24 and 72 hr, respectively. Since $ID_{50}$ value of above $1000{\mu}g/ml$ indicates very weak cytotoxicity, the ginseng protein seems to exert very weak cytotoxic effect on CHO-K1 cells.

• Asian Journal of Turfgrass Science
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• v.10 no.1
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• pp.71-80
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• 1996

Fourteen dictyostelids(12 species of genus Dictyostelium. 2 species of genus Polysphonylium) oc-curred in Mt. Chiri Korea. Soils samples were collected from the nine sites. In the broadleaved-deciduous forests and conifers, common species of cellular slime molds are Dictyostelium mucoroides, and D. brefeldianum. Only two species are above 30 in importance value and above 50% in presence. Dominant species in the broadleaved-deciduous forests is D. mecoroides wheras in the conifer forests is D. brefeldianum which was not common until now in Korea, found in the low elevation either. In addition, Five cellular slime molds occured in the Miscanthus sinensis community: 4 species of genus Dictyostelium and 1 species of genus Polysphonylium. Dominant species is D. purpureum. Importance value is very high, 85. This Result is exceptively unusual. It dind't occur in the other sites. Correlation between the altitudes and the occurrence and distribution of dictyostelids was not accurate. Merely dominant species were different according to forest types and organic matter contents in soil. Cellular slime molds have different favorite forest types. And the growth and germination are dependent on the soil enviroryrnental conditions and soil quility. Key words:Dictyostelids, Mt. Chiri D. mecoroides, D. brefeldianum. D. purpureum. Soil quility, Favorite forest type, Soil environmental condition.

• Molecules and Cells
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• v.45 no.1
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• pp.26-32
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• 2022

Living cells generate, sense, and respond to mechanical forces through their interaction with neighboring cells or extracellular matrix, thereby regulating diverse cellular processes such as growth, motility, differentiation, and immune responses. Dysregulation of mechanosensitive signaling pathways is found associated with the development and progression of various diseases such as cancer. Yet, little is known about the mechanisms behind mechano-regulation, largely due to the limited availability of tools to study it at the molecular level. The recent development of molecular tension probes allows measurement of cellular forces exerted by single ligand-receptor interaction, which has helped in revealing the hitherto unknown mechanistic details of various mechanosensitive processes in living cells. Here, we provide an introductory overview of two methods based on molecular tension probes, tension gauge tether (TGT), and molecular tension fluorescence microscopy (MTFM). TGT utilizes the irreversible rupture of double-stranded DNA tether upon application of force in the piconewton (pN) range, whereas MTFM utilizes the reversible extension of molecular springs such as polymer or single-stranded DNA hairpin under applied pN forces. Specifically, the underlying principle of how molecular tension probes measure cell-generated mechanical forces and their applications to mechanosensitive biological processes are described.

• Korean Journal of Head & Neck Oncology
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• v.18 no.2
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• pp.135-141
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• 2002

Backgrounds and Objectives: Metastasis is a complex multistep process that requires sequential interactions between the invasive cell and the extra-cellular matrix. Transforming growth factor-${\beta}1$ ($TGF-{\beta}1$) is a multifunctional regulator of cellular differentiation, motility and growth. Loss of sensitivity to the growth inhibitory effects by $TGF-{\beta}1$ plays important roles in neoplastic progression. The aim of this study was to investigate the role of $TGF-{\beta}1$ in the neoplastic invasion and metastasis through matrix metalloproteinase (MMP) of laryngeal cancer cell lines. Material and Methods: Two laryngeal cancer cell lines, SNU-899 and SNU-1076 were treated with recombinant $TGF-{\beta}1$, and the expression of MMP-2 and MMP-9 was immunohistochemically evaluated and gelatinase activity was studied by gelatin zymogram. Results: The cell growth inhibition was evident on 4th days after 1ng/ml and 10ng/ml $TGF-{\beta}1$ treatment. The expressions of MMP-2 and MMP-9, and their gelatinase activities were increased in dose-dependent manner. Conclusion: $TGF-{\beta}1$ treatment in laryngeal cancer cell lines induces the expression of MMP-2 and MMP-9, thus playing a role in the digestion of extracellular matrix gelatin.

• Fisheries and Aquatic Sciences
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• v.16 no.3
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• pp.149-158
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• 2013

We demonstrate enhanced growth, innate immunity and protection against hydrogen peroxide ($H_2O_2$)-induced protein oxidation and cellular DNA damage in olive flounder Paralichthys olivaceus fed a chitosan-coated moist pallet (MP) diet. A chitosan-based biopolymer coated MP as the experimental diet and a non-coated MP (control) was fed to olive flounder fish. Growth, including the average weight gain (g/fish), weight gain (%) and feed intake (g) of the fish group fed a chitosan-coated MP diet increased significantly. The survival rate was reported as 100% throughout the experimental period. Immunological parameters indicated higher mucus lysozyme activity and significantly higher fish skin mucus total protein content was observed in fish fed the chitosan-coated MP diet compared to the control. A blood plasma analysis revealed attenuation of cellular DNA and protein oxidative damage caused by $H_2O_2$-induced oxidative stress in the fish fed the chitosan-coated MP diet compared to the control group. Moreover, blood serum biochemical analysis revealed health-promoting effects, including significantly higher hemoglobin and total cholesterol levels in the fish fed the chitosan-coated MP diet compared to the control group. In conclusion, growth, innate immunity and protection against oxidative stresses were improved by feeding of the chitosan-coated MP diet to olive flounder reared in aquaculture.

• Preventive Nutrition and Food Science
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• v.3 no.1
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• pp.85-91
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• 1998

To investigate the effects of antioxidative vitamins in combination with various fatty acids on breast cancer cell proliferation, MDA-MB231 human breast cancer cells were cultured for 3 days in the serum-free Iscove's modified Dulbecco's medium (IMDM) supplemented with 1.25mg/ml delipidized bovine serum albumin and 10㎍/ml insulin. Alpha-tocopherol, ascorbic acid or both vitamins were added to the medium at the concentrations of 10 and 50μM in the presence of 3μg/ml of oletic(Oa), linoleic(LA) α-linoleinic(LNA) and docosahexaenoic acid(DHA). Cell growth was reduced significantly by α-tocopherol in a dose-dependent manner, but not affected by ascorbic aicd. The four different fatty acids did not have significant effects on cell growth, although DHA exerted inhibitory effect on the growth after 1 day. However, the each fatty acid was well incorporated into celluar lipid as such or elongated forms. Addition of α-tocopherol remarkably increased its celluar contents and reduced cellular levels of thiobarbituric acid substances (TBARS) that were elevated notably in the presence of DHA in the culture media. But ascorbic acid addition did not change much of either cellular α-tocopherol or TBARS contents. northern blot hybridization showed that tumor supressor gene ρ53 was most highly expressed by the combination of ρ-tocopherol and DHA in 8 hours of cell culture. In conclusion , the growth inhibitory effect of vitamin E suggests that breast cancer cell proliferation is reduced by the mechanism other than cytotoxicity of lipid peroxide and it is related to expressionof tumor supprosser gene p53, that can be increased by both vitamin E and n-3 fatty acid, DHA.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.10
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• pp.6007-6012
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• 2013

ANXA2, a member of the annexin family, is overexpressed and plays important roles in tumor development. However, the significance of ANXA2 expression in gastric carcinoma has not been clarified.To elucidate its roles in growth of gastric cancer, ANXA2 expression in SGC-7901 cells was inhibited with a designated siRNA, then cell proliferation, cell cycling, apoptosis and motility were determined by MTT assay, flow cytometry, Hoechst 33342 staining and wound healing assay, respectively. To further assess the behavior of ANXA2 deleted SGC-7901 cells, changes of microstructures were observed under fluorescence microscopy, laser scanning confocal microscopy and electron microscopy. We found that inhibition of ANXA2 expression caused cell proliferation to decrease significantly with G1 arrest, motility to be reduced with changes in pseudopodia/filopodia structure and F-actin and ${\beta}$-tubulin expression, and apoptosis to be enhanced albeit without significance. At the same time, ANXA2 deletion resulted in fewer pseudopodia/filopodia, non-stained areas were increased, contact inhibition among cells reappeared, and expression of F-actin and ${\beta}$-tubulin was decreased, with induction of polymerized disassembled forms. Taken together, these data suggest that ANXA2 overexpression is important to maintain the malignancy of cancer cells, and this member of the annexin family has potential to be considered as a target for the gene therapy of gastric carcinoma.