• Journal of Food Hygiene and Safety
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• v.1 no.1
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• pp.13-21
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• 1986

Two short-term bioassays were employed to asses the mutagenic and clastogenic activities in browning reaction of pentose-creatine, pentose-glycine and pentose-creatine-glycine browning reaction model system. Methylene chloride extract of rhamnose-creatine-glycine browning reaction exhibited the strongest mutagenicity toward Salmonella typhimurium TA98 with S-9. Methylene chloride extract of pentose-creatine and pentose-glycine browning reaction solutions was also tested for mutagenicity, with positive responses. Methylene chloride extract of pentose-creatine-glycine browning reaction solutions induced significant increase in chromosome aberrations in the treated Chinese hamster ovary(CHO) cells. Each of pentose-creatine and pentose-glycine browning reaction solutions induced a relatively low frequency of chromosome aberrations in the treated cells.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.53-56
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• 2002

Mammalian cell based biosensor kits are expected to be in assessment of samples toxicity more sensitive and accurate. A recombinant fluorescent Chinese Hamster Ovary (CHO) cell line was known to be responsive to the various toxicants Specially. KFC- AlO cell line. which contain the c-fos SRE::GFP plasmid (pKFG). was found to be able to detect toxicants sensitively. A biosensor kit was developed by using an immobilized KFC-A10 cell line. Immobilized recombinant fluorescent cells within agarose, known as a representative hydrogel matrix, have been maintained in the matrix viably and have shown constant fluorescent levels for long time. Immobilized cells have shown the ability to detect the chemical toxicity in the keep of fluorescent level as the metabolism is inhibited under toxic conditions.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.170.3-171
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• 2003

An efficient Erythropoietin (EPO)-expression system in mammalian cells is required for massive production for therapeutic use. Ammonium ion is a major problem in the production of valuable recombinant proteins in cultured animal cells. Therefore, it is of importance to devise a system by which a high productivity of human therapeutic recombinant protein can be maintained or enhanced under low ammonium concentration. To reduce the ammonium ion accumulated in EPO producing Chinese Hamster Ovary (CHO) ceels, IBE, we introduced the first two genes of the urea cycle, carbamoyl phosphate synthetase (CPSI) and arnithine transcarbamoylase (OTC), into IBE using a stable transfection method. (omitted)

• Biomedical Science Letters
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• v.14 no.4
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• pp.203-210
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• 2008

One of cell surface receptor proteins, human folate receptor (hFR) involves in the uptake of folates through cell membrane into cytoplasm, and is anchored to the plasma membrane by a fatty acid linkage, which has been identified in some cells as a glycosylphosphatidylinositol (GPI)-tailed protein with a molecular mass of about 40 kDa. The hFR is released by phosphatidylinositol phospholipase C (PI-PLC) because it contains fatty acids and inositol on the GPI tail. Caveolin decorates the cytoplasmic surface of caveolae and has been proposed to have a structural role in maintaining caveolae. It is unknown whether caveolin is involved in targeting, and is necessary for the function of GPI-tailed proteins. To compare the ability of folic acid binding, internalization and expression of hFR, and the effect of caveolin at the both apical and basolateral side of cell surfaces in Chinese hamster ovary (CHO) clone cells overexpressed the hFR and/or caveolin. Our present results suggest a possibility that the overexpression of caveolin does not be involved in expression of hFR, but plays a role as a factor in PI-PLC releasing kinetics, and for a regulation of formation, processing and function of hFR in CHO clone cells overexpressed cavcolin.

• Journal of Life Science
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• v.23 no.8
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• pp.963-969
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• 2013

Although it is popularly believed that vitamin C protects cells from various genotoxicants, the degrees and mechanisms of itsprotective actions are not fully understood. In this study, vitamin C's protective effects against various genotoxicants were quantified, together with subsequent analyses on the mechanisms of these protective effects. Comet assay was employed to measure the degree of DNA damage in Chinese hamster ovary cells (CHO-K1) exposed to five genotoxicants, $H_2O_2$, $HgCl_2$, N-methyl-N-nitro-N-nitrosoguanidine (MNNG), 4-nitroquinoline-1-oxide (4NQO), and UV-irradiation. In cases cells were treated with $H_2O_2$, $HgCl_2$, and 4NQO together with vitamin C, the damage to DNA decreased to the level of the control group. In cases of UV-irradiation, the protective effect of vitamin C appeared, but did not reach the control levels. Interestingly, vitamin C did not have protective effects against the genotoxicity of MNNG. The degrees of DNA damage of cells treated with vitamin C prior to exposure togenotoxicants were 28~49% lower than those of cells treated with vitamin C after being exposed to genotoxicants. In conclusion, vitamin C had strong antioxidanteffects against genotoxicants by being a primary antioxidant blocking genotoxicity reaching the cells, rather than being a secondary antioxidant acting on post-exposure DNA repair processes. However, vitamin C's protective effects appearto be limited, as there are genotoxicants, such as MNNG, whosegenotoxicityis not affected by vitamin C. Therefore, the results of this study warrant furtherstudies on toxic mechanisms of genotoxicants and their interactions with protective mechanisms of vitamin C.

• Environmental Mutagens and Carcinogens
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• v.10 no.2
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• pp.85-92
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• 1990

The effects of aphidicolin (APC), 2`,3`-dideoxythymidine 5`-triphosphate (ddTTP), and novobiocin (NOV) on the frequencies of chromosome aberrations induced by ethyl methanesulfonate (EMS) or bleomycin (BLM) were examined in synchronized Chinese hamster ovary (CHO)-K$_1$ cells. The cells were synchronized by the thymidine double block method. APC, ddTTP and NOV alone did not affect the frequencies of chromosome aberrations. The cells in late G$_1$ and early S phases were sensitive to the induction of chromosome aberrations by EMS, wherase cells in G$_2$ phase were most sensitive to chromosme aberration by BLM.

• Safety and Health at Work
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• v.2 no.1
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• pp.17-25
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• 2011

Objectives: In this study, the in vitro mammalian chromosomal aberration (CA) assay was conducted to gain additional information concerning the hazards associated with the use of cyclopentane and ammonium nitrate. While these two chemicals had already been tested by many methods, they had not been studied in the CA test. Methods: The assay was performed using the ovarian infantile cell (CHO-K1 cell), by the direct method (-S9) and by the metabolic activated method (+S9 mix). Results: Using the direct method, the 7 dosages in a 48 hour treatment group did not show that the frequency of CA is proportion to the dosage addition. The frequency of CA is not proportion to the dosage addition for a 6 hour treatment using the metabolic activated method. Conclusion: From these findings, it was decided that the 2 chemicals do not induce chromosomal aberrations under the tested conditions.

• YAKHAK HOEJI
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• v.39 no.1
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• pp.94-101
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• 1995

In order to evaluate the suppressive effects of galangin on the DNA damage induced by N-methyl-N-nitrosourea(MNU), in vitro sister chromatid exchange(SCE) test using Chinese Hamster ovary(CHO) cells was performed. Also the determinations of [$^{3}$H] MNU-induced total DNA binding and methylated DNA were performed to find out the mechanism of action by galangin. MNU-induced SCEs were significantly decreased by simultaneous and pretreatment of galangin when S-9 mix was added only. In post-treatment, however, the MNU-induced SCEs were not decreased when S-9 mix was added or not. [$^{3}$H] MNU-induced total DNA binding was significantly inhibited by the treatment of galangin in calf thymus DNA and CHO cells. HPLC analysis of DNA hydrolysates shows that galangin caused a dose-dependant decrease in calf thymus DNA, but not significant decrease in CHO cells. These results suggest that the inhibition of galangin on the MNU-induced SCEs is due to the decrease of DNA binding and methylation with MNU. Therefore, galangin may be useful as a chemopreventive agent of alkylating agents.

• Animal cells and systems
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• v.5 no.1
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• pp.77-83
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• 2001

The present study was conducted to elucidate whether the expression level of poly(ADP-ribose) polymerase (PARP) is related to the ultraviolet radiation (UV)-induced apoptosis. After treatment of the mammalian cell lines HeLa S3 and Chinese hamster ovary (CHO) with 50 J/m2 UV, induction of apoptosis was determined by several means during 24 h post-incubation. Incidence of apoptosis was much lower in CHO than HeLa S3 cells based on the percentage of apoptotic cells in terms of morphological changes in nucleus or direct counting of viable cells and qualitative or quantitative DNA fragmentation. Interestingly, when the expression level of PARP was measured by western blotting, the amounts of PARP that was retained at each time point inversely correlated with the incidences of apoptosis in these cells. Concomitant with generation of the 85 kDa fragment, 116 kDa PARP disappeared in HeLa S3 within 6 h after UV treatment, whereas a fair amounts of 116 kDa band was still retained in CHO cells at 36 h post-incubation. This inverse relationship was also observed in the adaptive response system, in which cells weve treated with a high dose of UV after pretreatment with a low dose. As expected, typical adaptive responses appeared in CHO cells but not in HeLa cells, showing greater cell viability and lesser DNA fragmentation. During the adaptive response in CHO cells, PARP was expressed at much higher level compared to the single, high dose-treated cells. Interestingly, even though PARP was induced at 6 h post-incubation In both cell types, its expression was more prominent in CHO cells. Thus, our data indicate that the retained level of intact PARP against UV damage inversely correlates with incidence of apoptosis in mammalian cells, and also suggest that a machinery to protect the PARP degradation against UV damage exists in CHO but not in HeLa S3 cells.

• Journal of Microbiology and Biotechnology
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• v.13 no.5
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• pp.759-766
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• 2003

Recombinant Chinese hamster ovary (rCHO) cell lines expressing a high level of human thrombopoietin (hTPO) or its analog, TPO33r, were obtained by transfecting expression vectors into dihydrofolate reductase-deficient (dhfr) CHO cells and subsequent gene amplification in media containing stepwise increments in methotrexate (MTX) level such as 20, 80, and 320 nM. The parental clones with a hTPO expression level $>0.40\;{\mu}g/ml$ (27 out of 1,200 clones) and the parental clones with a TPO33r expression level $>0.20\;{\mu}g/ml$ (36 out of 400 clones) were subjected to 20 nM MTX. The clones that displayed an increased expression level at 20 nM MTX were subjected to stepwise increasing levels of MTX such as 80 and 320 nM. When subjected to 320 nM MTX, most clones did not display an increased expression level, since the detrimental effect of gene amplification on growth reduction outweighed its beneficial effect of specific TPO productivity ($q_{TPO}$) enhancement at 320 nM MTX. Accordingly, the highest producer subclones ($1-434-80^{*}$ for hTPO and $2-3-80^{*}$ for TPO33r), whose $q_{TPO}$ was 2- to 3-fold higher than that of their parental clones selected at 80 nM MTX, were isolated by limiting dilution method and were established as rCHO cel1 lines. The $q_{TPO}$ of $1-434-80^{*}\;and\;2-3-80^{*}\;was\;5.89{\pm}074\;and\;1.02{\pm}0.23\;{\mu}g/10^6$ cells/day, respectively. Southern and Northern blot analyses showed that the enhanced $q_{TPO}$ of established rCHO cell lines resulted mainly from the increased TPO gene copy number and subsequent increased TPO mRNA level. The hTPO and TPO33r produced from the established rCHO cell lines were biologically active in vivo, as demonstrated by their ability to elevate platelet counts in treated mice.