The detection of many synthetic chemicals used in industry that may pose a genetic hazard in our environment is of great concern at present. Since these substances are not limited to the original products, and enter the environment, they have become widespread environmental pollutants, thus leading to a variety of chemicals that possibly threaten the public health. In this respect, to regulate and to evaluate the chemical hazard will be important to environment and human health. The clastogenicity of 17 synthetic chemicals was evaluated in Chinese hamster lung fibroblast cells in vitro. Two most cytotoxic chemicals, dodecyl methacrylate (CAS No. 142-90-5) and 2-ethylhexyl methacrylate (CAS No. 688-84-6), among 17 chemicals tested revealed no clastogenicity in the range of 0.0165-0.066 $\mu\textrm{g}$/$m\ell$ and 0.006-0.024 $\mu\textrm{g}$/$m\ell$ both in the presence and absence of metabolic activation system, respectively. All 17 chemicals revealed no significant induction of chromosomal aberration both in the presence and absence of metabolic activation system in this assay. From the results of chromosomal aberration assay with 17 synthetic chemicals in Chinese hamster lung cells in vitro, we did not observed positive clastogenic results in this study.

Hypertension is characterized by multiple genetic and environmental factors. To establish the genetic basis of hypertension in Koreans, we investigated the genetic variations of two candidate genes (aldosterone synthase (CYP11B2), ${\gamma}$ subunit of the amiloride-sensitive epithelial sodium channel (ENaC) in the Korean patients with hypertension and normotensive controls. There were no significant differences in the genotype and allele frequencies between two groups, respectively. However, there was the significant difference between Korean and Caucasian populations in allele frequency of RFLPs in the two candidate genes. Therefore, these studies also need to be confirmed in other ethnic groups, although our results do not support a possible role of these genes on hypertension in Korean population

Thimerosal, a widely used preservative, has been well known to induce intracellular calcium mobilization in various cell types. However, the mechanism of its calcium mobilization is not clearly understood yet. For studying the mechanism of thimerosal-mediated calcium release, we have used HL60 cells in calcium-free Lockes solution that has no extracellular calcium. Thimerosal significantly reduced the lag period of initial calcium release whereas it enhanced the rate and magnitude of the calcium release in a dose-dependent manner. At the same time, we found that thimerosal generated superoxide anion by activating NADPH oxidase in dose- and time-dependent manner. Interestingly, the kinetics and the dosedependency of superoxide anion generation were very similar to those of intracellular calcium mobilization. In inhibitors study, the thimerosal-induced superoxide anion generation was significantly suppressed by DMSO as well as superoxide dismutase but not by genistein or EGTA. Surprisingly, the pretreatment with N-Acetyl-$_{L}$-Cysteine blocked almost completely the thimerosal-induced calcium increase, indicating that ROS playa key role in the calcium mobilization. The present results suggest that thimerosal-induced calcium mobilization is possibly mediated by the activation of NADPH oxidase and subsequent ROS generation.n.

Using agarose-coupled methotrexate, we have successfully isolated two proteins, which have strong interactions with methotrexate. The two proteins were analyzed by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry and identified as carbamoyl-phosphate synthetase 2 and phosphoribosylglycinamide formyltransferase, respectively. Interestingly, both of these two proteins are essential key enzymes in nucleotide biosynthetic pathways, like dihydrofolate reductase, a well-known methotrexate target. We confirmed the specificity of their interactions between methotrexate and two target proteins by the methods of competition binding assay, which were followed by western blotting using antibody against carbamoyl-phosphate synthetase 2 and phosphoribosylglycinamide formyltransferase, respectively. Moreover, we could observe that carbamoyl-phosphate synthetase 2 is overexpressed in methotrexate-resistant MOLT-3 cells comparing with control MOLT-3 cells. This result indicates that carbamoyl-phosphate synthetase 2 may be a novel target of methotrexate in cancer therapy. We propose that chemical proteomics can be a powerful technique to identify target proteins of a chemical.

Prolonged exercise is known to increase steady-state serum high-density lipoprotein cholesterol (HDL-cholesterol) and apolipoprotein AI(apo AI) concentrations. We investigated the effect of adaptation to endurance exercise on the association of the genetic polymorphism in the apo AI gene with these biochemical parameters. 108 male subjects were randomly selected from a group of elite athletes, and 65 male samples used as sedentary control group from Korean general population. The genetic polymorphism in the apo AI gene locus was detected by polymerase chain reaction(PCR) and DNA digestion with Msp I restriction endonuclease. The genotype frequency for the Msp I RFLP was significantly different between the elite athletes and sedentary controls(P<0.05). There were, however, no significant associations between the Msp I RFLP of the apo AI gene and the biochemical parameters in elite athletic group. Therefore, our findings indicate that the Msp I RFLP of the apo AI gene was not associated with the serum apo AI and HDL-cholesterol concentrations in Korean male elite athletes.

Single cell gel electrophoresis assay was carried out to evaluate DNA damage in T-and B-lymphocytes from rats exposed to benzene and the correlation between DNA damage and the level of t,t-muconic acids, which are urinary benzene metabolites, was investigated. In control rats, the mean values of Olive tail moments in T-and B-lymphocytes were 1.507$\pm$0.187 and 1.579$\pm$0.206 respectively. DNA damages of T-lymphocytes in rats exposed for 4 weeks showed the highest Olive tail moments at each benzene concentration examined (2.72-4.351). However this DNA damage was decreased after 6 weeks of exposure (1.74-2.09). DNA damages of B-lymphocytes did not show such differences with exposure time or benzene concentration (1.49-2.07) except at 200 ppm at 4 weeks. T-lymphocytes show significantly more damages than B-lymphocyte upon acute exposure to benzene.

In order to determine the safety of chemicals and pharmaceutical products, various methods can be used to evaluate the toxicity. In this study the genotoxic effect of the widely used industrial chemical, cadmium chloride, was assessed using the micronucleus test in peripheral blood of mice. The presence of micronucleated reticulocytes by microscopic observation following acridine orange staining indicated a potential genotoxic effect. The genotoxicity of intraperitoneally (i.p.) administered cadmium chloride (0.5, 1, 2 mg/kg) appeared to be dose dependent, with the maximum tolerated dose (MTD) found to be 2 mg/kg. Compared to the negative control (saline), cadmium chloride (2 mg/kg) exhibited statistically significant genotoxic potential (P<0.05) but was found to be less than the positive control of mitomycin C (0.5 mg/kg) and was not statistically significant compared to historical negative controls (P>0.05).

Phthalate analogues are a plasticizer and solvent used in industry. Phthalates were reported to be a potential carcinogen classified in the category of suspected endocrine disruptors. Most common human exposure to these compounds may occur with contaminated food. They may migrate into food from plastic wrap or may enter food from general environmental contamination. Since these substances are not limited to the original products, and enter the environment, they have become widespread environmental pollutants, thus leading to a variety of phthalates that possibly threaten the public health. Concern about their use has been mounting. To screen and elucidate the endocrine disrupting activity and their mechanism of phthalate analogues, first of all, E-screen assay was performed in MCF7 human breast cancer cells with seven phthalate analogues. In this cell proliferation assay, only dibutyl phthalate (DBP) showed weak estrogenic activity. Also the yeast-based transcription assay to assess the interactions of DBP with the estrogen, androgen, and progesterone receptors was conducted. DBP in the concentration ranges from 10$^{-16}$ to 10$^{-11}$ M was active in the estrogen transcriptional assay, but it did not show the effect on $\beta$-galactosidase activity in the progesterone and androgen transcriptional assays. These data indicate that DBP shows estrogenic potential and can be classified as weak and/or suspected endocrine disrupting chemicals.

The dose dependence of the severity of radiation-induced thymic lymphoma in C57BL/6J mice was studied. Mice were exposed to fractionated irradiation at the total doses of 4.0, 6.0 and 8.0 Gy (four irradiations at 8-day intervals) starting from 33 days after birth. Pathological and histological changes of each mouse were observed after periodical sacrifice at day 75, 100, 125, 150, 175, 200, 250, 300 after the first irradiation. The severity of cancers were classified into 4 stages by clinical signs with respect to the enlargement of the thymus, spleen, liver, the progression of the cancer in the thymus, and the metastasis to the spleen, liver, lung and the lymphatic nodes. Among the 490 mice observed, 146 mice had thymic lymphoma. A clear dose-effect relationship was observed as well as the dose-response relationship. Also, periodical observation showed that thymic lymphoma was first induced in mice sacrificed at day 100 (130days old), and metastasize in the order of spleen, lung, liver and then the lymphatic nodes. The results suggest that radiation may be involved not only as a tumor initiator but also as a tumor promoter, and a tumor progression-enhancing agent.

Phthalates, suspected endocrine disruptor, are plasticizer and solvent used in industry, and some phthalates are known as potential carcinogen. Most common human exposure to this compounds may occur with contaminated food. It may migrate into food from plastic wrap or may enter food from general environmental contamination, and it has become widespread environmental pollutants, thus leading to a variety of phthalates that possibly threaten the public health. Dibutyl phthalate (DBP) may playa part of cell proliferator, which mediates changes in gene expression and the metabolism of xenobiotics. An understanding of the role of DBP in modulating gene regulation should provide insight regarding mechanisms of DBP induced xenoestrogenic impact. To elucidate the type of genes that are associated with estrogenic activity induced by DBP at the dose (10$^{-8}$ M) appeared proliferating effects, the pattern of gene expression in MCF7 cells was compared between 17$\beta$-estradiol and DBP exposure in the cDNA microarray. From the results, it showed some differences of gene expression patterns between MCF7 cells treated with 17$\beta$-estradiol and DBP, and also DBP shows estrogenic potential with changes in estrogen-related gene expression levels.

According to the epidemiological studies in chromium workers, hexavalent chromium is associated with the risk of lung cancer. Cellular oxidative damages by reactive oxygen species produced by hexavalent chromium exposure may play an important role in the carcinogenesis process. We investigated the availabilities of malondialdehyde measurement for the assessments of oxidative damages from chromium exposure with an experimental inhalation study in vivo. Lipid peroxidation, one kind of cellular oxidative damage, was measured in blood plasma of the rats which inhaled the hexavalent chromium mist for 1, 2 and 3 weeks. The concentrations of malondialdehyde (MDA), the metabolite of lipid peroxidation, in all exposed groups were higher than those of controls with dose-dependant manner. The levels of MDA were also correlated with urine chromium levels of the rats. Therefore, MDA as an indicator of lipid peroxidation could be proper biologic marker for the assessment of the oxidative damage from chromium exposure, which might be involved in carcinogenesis.

This study was conducted to quantify of micronucleus frequencies in human umbilical cord blood by supravital staining method with acridine orange, and to find some factors that affected on micronucleus frequncies in humans. In this study, we used umbilical cord blood of new born infants that have sufficient reticulocytes compared with adult peripheral blood. The cord bloods were taken after childbirth from 60 normal infants in industrial and coastal region in Korea. The total of 3 ${mu}ell$ cord blood was applied to slide coated with acridine orange, and micronuclei were observed under fluorescent microscopy. Demographic factors and independent variables were collected from mothers by questionnaire. The frequencies of micronuclei in umbilical cord blood of new born infants were 0-5 per 2,000 reticulocytes by supravital staining method, and mean value and standard deviation were 1.75$\pm$0.97. There were no significant difference by the regions, smoking habits of father or mother. However, age of mother showed significant positive correlation with frequencies of micronuclei (p<0.05). Smoking at home by fathers also was found as a significant variable by muliple regression analysis. Therefore, further studies would be needed for genotoxicological evaluation of new born infants by microneuli test using supravital staining method.

In recent years, the safety of sunscreens have been challenged based on the reports of its adverse effects on users; dermatitis, allergic contact dermatitis, photoallergic contact dermatitis. In the toxicological aspect, the need to investigate the safety of sunscreens is steadily increasing. However, there were few studies on the correlation between sun protection factor (SPF) and the safety of sunscreens. The objective of this study was to assess whether there was a correlation between SPF and the skin irritation index of sunscreens. Octyl methoxycinnamate (OMC) was selected, which was the most frequently used (about 92% in korea and about 90% in the world) in sunscreens. In vitro SPF test was performed using the standard samples recommended by KFDA guideline. We examined primary and cumulative skin irritation and eye irritation of OMC standard sample as well as homosalate. As in vitro SPF was increased, skin irritation index was increased in primary skin irritation test ($r^2$=0.986) and cumulative skin irritation test ($r^2$=0.939). In addition, OMC was non-irritating and non-sensitizing. In this results, there was a good correlation between SPF index and skin irritation index.

This study evaluated the concentrations of urinary metabolites of polycyclic aromatic hydrocarbons (PAHs) in industrial waste incineration workers. The effect of genetic polymorphisms of xenobiotic metabolism enzymes on urinary concentration of PAH metabolites was assessed. And, aromatic DNA adduct levels were also determined in total white blood cells. Fifty employees were recruited from a company handling industrial wastes located in Ansan, Korea: non-exposed group (n=21), exposed group (n=29). Sixteen ambient PAHs were determined by GC/MSD (NIOSH method) from personal breathing zone samples of nine subjects near incinerators. Urinary 1-hydroxypyrene glucuronide (1-OHPG), a major pyrene metabolite, was assayed by synchronous fluorescence spectroscopy after immunoaffinity purification using monoclonal antibody 8E11 (SFS/IAC). Multiplex PCR was used for genotyping for GSTMI/TI and PCR-RFLP for genotyping of CYP1A1 (MspI and Ile/Val). PAH-DNA adducts in peripheral blood WBC were measured by the nuclease P1-enhanced postlabeling assay. Smoking habit, demographic and occupational information were collected by self-administered questionnaire. The range of total ambient PAH levels were 0.00-7.00 mg/㎥ (mean 3.31). Urinary 1-OHPG levels were significantly higher in workers handling industrial wastes than in those with presumed lower exposure to PAHs (p=0.006, by Kruskal-Wallis test). There was a statistically significant dose-response increase in 1-OHPG levels with the number of cigarettes consumed per day (Pearson correlation coefficient=0.686, p<0.001). Urinary 1-OHPG levels in occupationally exposed smoking workers were highest compared with non-occupationally exposed smokers (p=0.053, by Kruskal-Wallis test). Smoking and GSTMI genotype were significant predictors for log-transformed 1-OHPG by multiple regression analysis (overall model R²=0.565, p<0.001), whereas smoking was the only significant predictor for log-transformed aromatic DNA adducts (overall model R²=0.249, p=0.201). Aromatic DNA adducts was also a significantly correlation between log transferred urinary 1-OHPG levels (pearson's correlation coefficient=0.307, p=0.04). However, the partial correlation coefficient adjusting for Age, Sex, and cigarette consumption was not significant (r=0.154, p=0.169). The significant association exists only in individuals with the GSTMI null genotype (pearsons correlation coefficient=0.516, p=0.010; partial correlation coefficient adjusting for age, sex, and cigarette consumption, r=0.363, p=0.038). Our results suggest that the significant increase in urinary 1-OHPG in the exposed workers is due to higher prevalence of smokers among them, and that the association between urinary PAH metabolites and aromatic DNA adducts in workers of industrial waste handling may be modulated by GSTMI genotype. There results remain to be confirmed in future larger studies.

Dioxin represents a group of halogenated aromatic hydrocarbons of which 2,3,7,8-tetrachlorod-ibenzo-p-dioxin (TCDD) is well known for its extremely toxic properties as well as ubiquitous presence in our environment and ecosystems. In order to better assess the carcinogenic mechanism of dioxin, we should utilize the reliable biomarkers that can precisely and correctly reflect multi-stage carcinogenesis. When MCF10A cells were exposed to TCDD (10 nM), expression of both CYP1A1 and CYP1B1 was induced in a time-related manner. The expression as well as activity of ornithine decarboxylase was transiently induced by TCDD treatment. In contrast, the induction of COX-2 that is implicated in carcinogenesis as well as inflammation, was not induced by TCDD. In another study, gap-junctional intercellular communication (GJIC) was attenuated by TCDD treatment as revealed by the dye-transfer assay. Based on these findings, TCDD has both tumor initiating and promoting potential in human breast epithelial cells in culture. Also, treatment of MCF10A cells with the carcinogen 7,12-dimethylbenz[a]anthracene plus TCDD resulted in malignant cell transformation as revealed by increased anchorage-independent growth of exposed cells. Additional studies may be necessary to assess the effects of TCDD on multi-stage carcinogenesis in vivo.

In order to investigate the safety of Aralia elata extract causing the reduction in the blood glucose level and oxidative stress in diabetes animals, these genotoxicity studies in bacterial and mammalian cell assay system such as Ames bacterial reverse mutation test and chromosomal aberration assay were performed. As results, in Ames bacterial reversion assay the extract in the range of 5,000-625 ug/plate did not induce mutagenicity in Salmonella typhimurium TA 98, TA 100, TA 1535 and TA 1537 strains with and without metabolic activation of S-9 mixture. For chromosomal aberration assay, $IC_{50}$ (50% inhibition concentration of cell growth) of the extract were determined; 792 $\mu\textrm{g}$/$m\ell$ without and 524 $\mu\textrm{g}$/$m\ell$ with S-9 mixture in Chinese hamster lung (CHL) fibroblast cell culture. Any significant chromosomal aberration was not observed in CHL cells treated with the extract at the concentrations of 792, 396 and 198 $\mu\textrm{g}$/$m\ell$ or 524, 262 and 131 $\mu\textrm{g}$/$m\ell$ in the absence or presence of S-9 metabolic activation, respectively. From these results, Aralia elata extract did not induce any harmful effects on the gene in bacteria and mammalian cell system used in these experiments.

Bisphenol A (BPA) is a monomer widely used in the manufacturing polycarbonate plastics or epoxy resin, and xenobiotics recently known as endocrine disrupting chemical. In this paper, to assess the effects of bisphenol A on immunopathological parameters (body weight, organ weight, hematological parameters, cellularity and surface marker) in mice, ICR female mice were orally exposed to BPA dissolved in olive oil as concentrations of 100, 500, 1000 ㎎/㎏/day b.w. 5 days a week for 30 days (subacute exposure). Liver - and kidney weight was significantly increased as dose-dependent manner, but body- , spleen- and thymus- weight didn't changed. In hematological parameters, WBC and MCHC were lowered but HCT and MCV were siginificantly enhanced. There was no significant differences in peritoneal macrophages number of the mice exposed to BPA. However, number of splenocytes of spleen, CD3/sup +/ and CD4/sup +/ cell in splenocytes, CD4/sup +/ and CD8/sup +/ cell in thymocytes were decreased at the mice subacutely exposed to BPA. In addition, BPA decreased expression of B7-1 and B7-2 on macrophages. Therefore, these results showed BPA may affect hematological parameters, cellularity and surface marker of immunocytes.