The purpose of this study was to evaluate whether the MTHFR variants, folate and vitamin $B_{12}$ deficiencies increase the risk of hyperhomocysteinaemia and adverse pregnancy outcome such as short gestational age or reduced birth weight. Healthy pregnant women (n=136; 24-28 gestational weeks; 20-40 years old), who visited Ewha Womans University Hospital for prenatal care, participated in this study. At the time of delivery, trained nurses recorded the pregnancy outcome from medical chart. We determined maternal MTHFR polymorphisms (C to T subsitution at nucleotide 677) and measured serum homocyteine, vitamin $B_{12}$, and folate concentrations. We compared serum homocysteine level by MTHFR genotype, serum folate and serum vitamin B12 levels using ANOVA. To evaluate the association between serum homocysteine level and pregnancy outcome, we compared the gestational age and birth weight by serum homocysteine levels using multiple regression analysis, adjusting for other potential predictors. Mean level of serum homocysteine was highest among pregnant women of the MTHFR variants with low levels of serum folate and vitamin $B_{12}$. Regarding association with birth outcome, we found the relationship between homocysteine levels and increased gestational age (p=0.03) and reduced birth outcome (p>0.05). Our data demonstrates that serum level of folate and vitamin $B_{12}$ among pregnant women affects significantly serum homocysteine levels, and the genetic polymorphism of MTHFR modulates the relationship between them. However, we did not have conclusive evidence of association between high homocysteine level and adverse pregnancy outcome such as preterm or low birth weight.

Hypertension is characterized by multiple genetic and environmental factors. To establish the genetic basis of hypertension in Koreans, we investigated the genetic variations of dopamine D3 receptor (DRD3) gene in the Korean patients with hypertension and normotensive controls. There were no significant differences in the genotype and allele frequencies of Bal I RFLP in the DRD3 gene between two groups, respectively (P > 0.05). Our finding shows lack of association between a genetic marker of DRD3 gene and hypertension, suggesting that the genetic variation of DRD3 gene does not playa major role in the determination of hypertension in Korean population. Further studies in other ethnic groups will be required.

Gap junctional intercellular communication (GJIC) plays a key role during development, process of tissue differentiation, and in maintenance of adult tissue homeostasis. Neural stem cells leading to formation of cell clusters termed 'neurospheres', can differentiate into neurons, oligodendrocytes, and astrocytes. We investigated the expression levels and distribution of connexin43 (Cx43) and connexin32 (Cx32), abundant gap junctional protein in neural cells and in neurospheres isolated from rat fetus embryonic day (ED) 17. During differentiation of neurospheres, expression of Cx43 and 32 were increased time-dependently within 72 h, and then decreased at 7 day in western blot analysis. TPA-induced inhibition of GJIC was confirmed by decreased fluorescence by SL/DT assay, and induced hyperphosphorylation of Cx43 while no changes in Cx32 levels in western blot assay. Our results indicate that GJIC may be a crucial role in the differentiation of neuronal stem cell. And this GJIC can be inhibited by TPA through the hyperphosphorylation of Cx43.

Single nucleotide polymorphisms (SNPs) are alterations in DNA base that occur most frequently throughout the human genome. The SNPs of DNA repair genes, hMLH1, hMSH2 and ATM, among 100 Korean people were analyzed using Dynamic Allele specific Hybridization (DASH) techniques. Mutation at the position of exon 38 (GA) and exon 10 (CG) of ATM gene, mutation at the position of exon 8 (AG), and exon 1 (AG) of hMLH1 gene and exon 14 (AG) of hMSH2 gene were investigated. No mutation at the selected position of ATM gene and hMSH1 gene was found. However, while there was no mutation at the position of exon of hMSH2 gene, mutation was found at the promotion region (CT) with the frequency of 24% CC, 36% CT and 62% TT genotyes. This results might be used as baseline data for research on SNP of Korean population.

To determine the frequencies of the genotypes of estrogen metabolising enzyme (CYP17, CYP1A1, CYP1B1, and COMT) and to identify the high-risk genotypes of these metabolic enzymes to breast cancer in Korean, the author has analysed 115 breast cancer patients and corresponding age and sex matched heathy controls using polymerase chain reaction-restiction fragment length polymorphism (PCR-RFLP). A2/A2 genotype in CYP17 polymorphism, m2/m2 genotype in CYP1A1 polymorphism, and Val/Val genotype in CYP1B1 had 0.95, 1.40 and 0.76 relive risks to breast cancer comparing with reference genotypes of each polymorphism, respectively. Among the genotypes of COMT enzyme polymorphism, L/H and L/L genotypes had 0.97 and 1.54 relative risks to breast cancer, respectively. According to the number of high risk genotype, the patients with one or two putative high risk genotypes had 0.95 and 1.94 relative risks to breast cancer, respectively. This study have demonstrated the unique frequency of genotypes of estrogen metabolizing enzyme in Korean healthy women, which will provide the basic data and insights to study the estrogen related conditions in Korean women including breast and endometrial cancers. And it also indicates that the well-known high risk genotypes of estrogen metabolizing enzymes are not significantly associated with the development of breast cancer in Korean women.

Recent industrial society has human widely exposed to PAHs (polynuclear aromatic hydrocarbons) that are comming from the incomplete combustion of organic material as wider spread environmental contaminants. Biological activities of PAHs are not known although PAHs are considered as carcinogens. Our laboratory have been studied the effect of PAHs in the mouse liver hepa 1 cells. In this study, we examined the mouse liver hepa-l cells as a new bioassay system to evaluate bioactivity of PAHs. We have selected 13 PAHs to examine bioassay using cyp1a1-luciferase reporter gene expression system where cyp1a1 1.6 Kb 5flanking region DNA was cloned in front of luciferase reporter gene and this plasmid was transfected into hepa 1 cells transiently. This cells then used for the study to observe the effect of PAHs. We demonstrated that PAHs induced the CYP1A1 promoter and 7-ethoxyresolufin O-deethylase (EROD) activities in a concentration-dependant manner. Some of PAHs showed stronger stimulatory effect on CYP1 gene expression than TCDD. Acenaphthene, anthracene, fluorine, naphthalene, pyrene, phenanthrene, carbazole were weak responders to cyp1a1 promoter activity stimulation and EROD induction in hepa 1 cells and these chemicals seemed to respond less to EROD than cyp1a1 promoter activity. Benz(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, chrysene, and dibenzo(a,h)anthracene showed strong response to cyp1a1 promoter activity stimulation and also EROD induction in hepa 1cells. Results of dose response study suggested that four strong responding PAHs, such as benzo(a)anthracene benzo(k)fluoranthene, chrysene, and dibenzo(a, h)anthracene might be mediated through arylhydrocarbon receptor system in hepa1 cells.

Polycyclic aromatic hydrocarbons (PAH) are frequently detected in food, water, soil, and sediment and are widespread environmental pollutants formed by the incomplete combustion of fossil fuels, woods and other organic matter. PAHs are considered to be probable human carcinogens. The mechanism of action of PAHs has been studied extensively, however it is not clear how PAHs turn on CYP1A1 in human breast cancer. Our laboratory have been studied the effect of PAHs in the human breast cancer cell MCF7. In this study, we examined the ZR-75-1 human breast cancer cells as a new system to evaluate bioactivity of PAHs. ZR-75-1 human breast cancer cell line responses to estrogen and progesteron. We have been able to estbilish long term culture system of this cells then used for the study to observe the effect of PAHs. We demonstrate that PAHs induced the CYP1A1 promoter and 7-ethoxyresolufin O-deethylase (EROD) activity in a concentration-dependant manner. RT-PCR analysis indicated that PAHs significantly up-regulate the level of CYP1A1 mRNA. Some of PAHs showed stronger stimulatory effect on CYP1 gene expression than TCDD. Apparently, ZR-75-1 cells have Aryl hydrocarbon receptors, therefore it would be good experimental tool to study the cross-talk between PAHs and steroid actions.