• Journal of Ginseng Research
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• v.31 no.4
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• pp.203-209
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• 2007

This study examined the extraction yields, total phenolic compounds content and the antioxidant activities on V79-4 cells of white ginseng extracts prepared by enzyme treatment. Yields of crude extract were 29.5-76%, and total phenolic compounds content showed 0.45-2.2% according to enzyme treatments. Pectinase treatment group showed the highest values of extraction yields and total phenolic compounds content. Pectinase and a-amylase treatment groups protected V79-4 cell viability(above 50%) against $H_2O_2$-induced oxidative damage. In the result of antioxidant enzyme activity evaluation in cells, enzyme treatments did not show the significant difference of SOD activity (p>0.05). However, pectinase treatment group exhibited increased CAT and GPx activities (p>0.05). Also, pectinase and protease treatment group inhibited MDA formation (>50%) in the lipid peroxidation protection experiment.

• Biomedical Science Letters
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• v.11 no.2
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• pp.165-173
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• 2005

A potent demethylating agent, 5-Azacytidine (5-AzaC) has been widely used as in many studies on DNA methylation, regulation of gene expression, and cancer biology. The mechanisms of the demethylating activity were known to be formation of complex between DNA and DNA methyltransferase (MTase), which depletes cellular MTase activity. However, 5-AzaC can also induce hypermethylation of a transgene in a transgenic cell line, G12 cells and it was explained as a result of defense mechanisms to inactivate foreign gene(s) somehow. This finding evoked the question that whether the phenomenon of hypermethylation induced by 5-AzaC is limited to the transgene or it can be occurred in endogenous gene(s). In order to answer the question, mutagenicity test of 5-AzaC and molecular characterization of mutants obtained from the test were performed using an endogenous gene, thymidine kinase (tk) in Chinese hamster V79 cells. When V79 and V79-J3 subclone cells were treated with 1, 2.5 ,5, $10{\mu}M$ of 5-AzaC for 48 hours, their maximum mutant frequencies were revealed as $6\times10^{-3}\;at\;5{\mu}M$(350-fold induction over background) and $8\times10^{-3}\;at\;2.5{\mu}M$ (l,800-fold induction over background) respectively. Since the induction rates were too high to be induced by true mutations, many trifluorothymidine (TFT)-resistant $(TFT^R)$ cells were subjected to Northern blot analysis to check the presence of tk transcripts. Surprisingly, all clones tested possessed the transcripts in a similar level, that implicates the $TFT^R$ phenotype induced by 5-AzaC has not given rise to hypermethylation of the gene in spite of unusually high mutation frequency. In addition, it has shown that the TK activity in the pool of 5-AzaC-induced $TFT^R$ cells has about a half of that in spontaneously-induced $TFT^R$ cells or in non-selected parental V79-J3 cells. This result suggests that the mechanism(s) underlying the TFT-resistance between spontaneously occurred and 5-AzaC-induced cells may be different. These findings have shown that the $TFT^R$ phenotype induced by 5-AzaC has not given rise to hypermethylation of the tk gene, and 5-AzaC may be induced by one or combined pathways among many drug resistance mechanisms. The exact mechanisms for the 5-AzaC-induced $TFT^R$ phenotype remain to elucidate.

• Toxicological Research
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• v.9 no.2
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• pp.159-166
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• 1993

The treatmene of V79 cells with diethyl maleate (DEM) led to decrease in glutathione (GSH) level as increasing DEM concentration. Mercuric chloride, treated for 6 hrs with 2ng/ml, affected the GSH metabolizing enzymes glutathione S-transferase (GST) and glutathione peroxidase (GSP), dropping their activities to 60% and 75%, respectively, though not so much in GSH level(80%). However, the toxic effects of mercuric chloride on those enzymes and GSH level were both amplified when the Hg2+ treatment was combined with the preceding DEM treatment.

• Korean journal of food and cookery science
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• v.22 no.4 s.94
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• pp.428-437
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• 2006

To investigate the worth of herbs as functional food ingredients, the antioxidant activity of 15 kinds of herb mathanol extracts was evaluated. Green tea, chamomile, dandelion, and lemon vervena extracts, with IC$_{50}$ values of 1.45 g/100mL, 1.49 g/100mL, 1.50 g/100mL and 1.55 g/100mL, respectively, had significantly higher superoxide radical scavenging activity than any other herb extracts. Green tea and lemon vervena extracts, which had high radical scavenging activity, showed inhibition of cell proliferation in Chinese hamster lung fibroblasts (V79-4 cells). Most herb extracts, except for chamomile, fennel and dandelion enhanced cell viability against H$_2$O$_2$-induced oxidative damage in V79-4 cells. At a dose of 1600 ${\mu}$g/mL, lemon vervena, green tea, hawthorn and rosemary extracts showed a cell viability of more than 50% which was significantly higher than that of the control culture treated with only H$_2$O$_2$ Thus, the results suggest that some herb extracts exhibited a V79-4 cell protective effect. The investigation of the cellular antioxidant enzymes activities of the five selected herb extracts revealed that extracts of lemon vervena and chamomile dose-dependently increased superoxide dismutase and glutathione peroxidase activity but that this increase was not significant. In conclusion, some natural herb extracts exhibited high antioxidant activity.

• Journal of Microbiology and Biotechnology
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• v.7 no.1
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• pp.62-67
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• 1997

To enhance the hyperproductive and low energy-consuming ethanol fermentation rate, the thermotolerant yeast S. cerevisiae RA-74-2 cells were immobilized. An efficient immobilization condition was proved to be $1.5{\%}$ (w/v) alginate solution, neutral pH and 20 h activation of beads. The fermentation characteristics and stability at various temperatures were examined as compared with free S. cerevisiae RA-74-2 cells. The immobilized cells had excellent fermentation rate at the range of pH 3-7 at 30-$42^{\circ}C$ in 15-$20{\%}$ glucose media. When the seed volume was adjusted to 0.12 (v/v) (6ml bead/50 ml medium), $11{\%}$ (w/v) ethanol was produced during the first 34 hand $12.15{\%}$ (w/v) ethanol [$95{\%}$ (w/v) of theoretical yield] during the first 60 h in $25{\%}$ glucose medium. In repetitive fermentation using a 2 litre fermentor, 5.79-$7.27{\%}$ (w/v) ethanol [76-$95{\%}$ (w/v) of theoretical yield] was produced during the 40-55 h in $15{\%}$ glucose media. These data suggested the fact that alginate beads of thermotolerant S. cerevisiae RA-74-2 cells would contribute to economic and hyperproductive ethanol fermentation at high temperature.

• IMMUNE NETWORK
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• v.2 no.2
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• pp.79-85
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• 2002

Background: In contrast to evidences of Ig H chain receptor editing in transformed cell lines and transgenic mouse models, there has been no direct evidence that this phenomenon occurs in human developing B cells. Methods: $V_HDJ_H$ rearrangements were obtained from genomic DNA of individual $IgM^-$ B cells from liver and $IgM^+B$ cells from bone marrow of 18 wk of gestation human fetus by PCR amplification and direct sequencing. Results: We found three examples of H chain receptor editing from $IgM^+$ and $IgM^-human$ fetal B cells. Two types of $V_H$ replacements were identified. The first involved $V_H$ hybrid formation, in which part of a $V_H$ gene from the initial VDJ rearrangement is replaced by part of an upstream $V_H$ gene at the site of cryptic RSS. The second involved a gene conversion like replacement of CDR2, in which another $V_H$ gene donated a portion of its CDR2 sequence to the initial VDJ rearrangement. Conclusion: These data provide evidence of receptor editing at the H chain loci in developing human B cells, and also the first evidence of a gene conversion event in human Ig genes.

• International Journal of Oral Biology
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• v.30 no.4
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• pp.117-123
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• 2005

Various aspects of antioxidant activity in vitamin C were evaluated in this study. Relatively high level of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was detected in vitamin C, but not in non-antioxidative vitamin, vitamin B1. Vitamin C also reduced the production of lipid peroxidation in Chinese hamster lung fibroblast (V79-4) cells with $IC_{50}$ value of $4{\mu}g/ml$. Vitamin B1 showed comparable reduction in lipid peroxidation products ($IC_{50}$ value was about $10{\mu}g/ml$). It was shown that vitamin C also dose-dependently enhanced the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) in V79-4 cells, and these effects were not observed in vitamin Bl-treated cells. Our data suggest that well-known antioxidant vitamin C involved in direct activation of SOD, CAT and GPX.

• Korean Journal of Pharmacognosy
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• v.36 no.1 s.140
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• pp.34-37
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• 2005

Reactive oxygen species (ROS) are known to cause oxidative modification of DNA, proteins, lipids and small cellular molecules and are associated with tissue damage and are the contributing factors for inflammation, aging, cancer, arteriosclerosis, hypertension and diabetes. We screened the anti-oxidants in V79-4 hamster lung fibroblast cells induced by hydrogen peroxide with eighteen pure compounds isolated from natural products. Allantoin, brassicasterol, and hypaconitine were found to strongly scavenge intracellular reactive oxygen species, which is measured by dichlorodihydrofluorescin diacetate method (DCHF-DA), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.222-227
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• 2005

To evaluate the antimutagenic activity of the specialty rices, a giant embryonic rice and a pigmented rice, we measured the inhibitory effect on the chemically induced mutagenesis in E. coli and V79 cultured cell system, as well as on DNA strand scission induced by oxidative damages in vitro. When the inhibitory activity to mitomycin C-induced mutagenesis using SOS chromotest in E. coli cell was measured, the activities decreased in the following order: germinated pigmented rice (40.4%) > germinated giant embryonic rice (37.1%) > pigmented rice (35.5%) > germinated brown rice (15.7%) > giant embryonic rice (14.0%) > brown rice (0.8%). The activities for inhibiting mitomycin C-induced DNA strand scission decreased in the order of pigmented rice > giant embryonic rice > germinated pigmented rice > germinated brown rice > brown rice > germinated giant embryonic rice. We also determined antimutagenic activities of the specialty rices using the suppressing effect on 6-TG resistant colony formation by 4-NQO in V79 cells as a mutagenicity index. The order of antimutagenicity was germinated giant embryonic rice (53.2%) > pigmented rice (40.0%) > brown rice (21.2%) > germinated brown rice (14.4%) > giant embryonic rice (0.23%); in contrast, germinated pigmented rice showed promoting effect on 4-NQO-induced mutagenesis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.100-104
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• 2011

In this work, an optimum condition of electrolytes preparation for photovoltaic cells application was investigated experimentally in terms of impedance and conversion efficiency of the cells. 3-methoxyppropionitrie and redox pairs with LiI and $I_2$ were used as stable solvents for fabrication of electrolyte. Efficiency comparison of the prepared cells carried out for various additives and ionic liquids. From the results, there was an optimum concentration (about 0.3 M) of ionic liquids for efficient cell fabrication. For case of electrolyte using single DMAp additive, the maximum conversion efficiency of the cell was 6.4%($V_{oc}$: 0.78V, $J_{sc}$: 14.4 mA/$cm^2$, ff: 0.57). For case of electrolyte using both DMAp and CEMim additives, the maximum conversion efficiency of the cell was 7.2%($V_{oc}$: 0.79V, $J_{sc}$: 16 mA/$cm^2$, ff: 0.57). From the result of electrochemical impedance measurement, both Z1 and Z3 values of binary additives-based cell decreased compared to those of single additive-based. This is due to the decreased in internal and charge transfer resistivities of the cells.