- Email: [email protected]
Damage of DNA after occupational exposure to 1,3-butadien by the comet assay
246
Abstracts~Mutation Research 360 (1996) 201-300
Cytogenetic detectable DNA damage, once induced, is normally eliminated in few cell cycles - through cell selection or cell death - owing to its inconsistency with cell viability or cell cycle progression. In the case of sister chromatid exchanges (SCE), on the other hand, it is known that an increase in their rate is not incompatible with cell survival and division. The possibility to detect DNA damage able to modify cytogenetic parameters and - once induced - to fix (to be inherited through cell cycles) in a given cell population, is in our opinion an interesting goal to evaluate the effectivity of processes eventually connected with the induction of cancer. We previously showed the inheritability of an increase in the SCE rate in CHO cells treated with a single pulse of demethylating agents (ethionine (ETH) and 5-azacytidine (AZA)), in contrast with the rapid ( 2 - 4 cell cycles) elimination of the damage in cells treated with Mitomycin-C (MMC) or 254 nm UV-light (UV). These findings were explained, suggesting a relation between the inherited increase in the SCE rate and the inherited modification in the genomic methylation level (2). In the present report we treated CHO-K1 cells with a single pulse of both ETH or AZA plus, starting from the end of the pulse up to 4 cell cyles later, a known mutagen agent (MMC or UV). In these conditions: (i) combined treatments of demethylating agents with the mutagen used, are able to induce synergistic increase in the SCE rate; (ii) this synergistic increase is induced even if the mutagen is supplied up to 4 cell cycles after the removal of the demetbylating agent. Data are considered to be in agreement with the hypothesis that the effect induced by both demethylating agents is an epigenetic inheritable modification leading to a damage proneness of the cells affected. 4-25
Central Bohemia, Prague, Czech Republic, ~ Institute of Occupational Health, Helsinki, Finland Comet assay (SCGE) is powerful method for studying DNA strand breaks and alkali labile sites in DNA supercoil. The method was used to determine damage in human lymphocytes after exposure to potential carcinogen 1,3-butadien (1,3-BD). The group of donors consisted of exposed (n = 19) and control (n = 19) subjects from 1,3-BD production at Kau~uk Kralupy plant. Exposure to 1,3-BD during working shift was determined by personal monitors. Exposure of 2 exposed and 11 control subjects was lower than detection limit. Median of exposure for the control group was 6.5 × 10 3 (range 4.5 × 10 3-0.16) and for the exposed subjects 0.35 (3.3 x 10-3-21) ppm of 1.3-BD ( p > 0.001). Ambient air concentration of 1,3-BD at working place was lower than 0.5 ppm (1 mg/m3). Blood was collected at the end of working shift. The Comet assay was performed on lymphocytes frozen after isolation from blood and stored under liquid nitrogen until analysed. Dead cells were scored in each thawed sample (trypan blue exclusion), 100 cells per person were scored on image analyzer. 5 comet parameters were evaluated for each individual. We did not find significant differences between exposed and control groups for any of the comet parameters. Although the exposure was low, analysis of variance resulted in a significant effect of personal exposure on percentage of DNA in tail of the comet images ( p = 0.02). The results indicate, that 1,3-BD exposure lower than 1 ppm does not induce significant damage to DNA determined by tail length and tail moment. 4-26
Damage of DNA after occupational exposure to 1,3-butadien by the comet assay
Exposure to genotoxic compounds in air pollution. DNA- and protein adducts as markers of exposure and influence of GST~ genotype
K. Peterkovfi, K. Peltonen ", R. Srfim; Laboratory of Genetic Ecotoxicology, Regional Inst. of Hygiene of
P. Sabro, H. Okkels, A.B. Vestergaard, H. Autrup; Department of Environmental and Occupational
Abstracts~Mutation Research 360 (1996) 201-300
Cytogenetic detectable DNA damage, once induced, is normally eliminated in few cell cycles - through cell selection or cell death - owing to its inconsistency with cell viability or cell cycle progression. In the case of sister chromatid exchanges (SCE), on the other hand, it is known that an increase in their rate is not incompatible with cell survival and division. The possibility to detect DNA damage able to modify cytogenetic parameters and - once induced - to fix (to be inherited through cell cycles) in a given cell population, is in our opinion an interesting goal to evaluate the effectivity of processes eventually connected with the induction of cancer. We previously showed the inheritability of an increase in the SCE rate in CHO cells treated with a single pulse of demethylating agents (ethionine (ETH) and 5-azacytidine (AZA)), in contrast with the rapid ( 2 - 4 cell cycles) elimination of the damage in cells treated with Mitomycin-C (MMC) or 254 nm UV-light (UV). These findings were explained, suggesting a relation between the inherited increase in the SCE rate and the inherited modification in the genomic methylation level (2). In the present report we treated CHO-K1 cells with a single pulse of both ETH or AZA plus, starting from the end of the pulse up to 4 cell cyles later, a known mutagen agent (MMC or UV). In these conditions: (i) combined treatments of demethylating agents with the mutagen used, are able to induce synergistic increase in the SCE rate; (ii) this synergistic increase is induced even if the mutagen is supplied up to 4 cell cycles after the removal of the demetbylating agent. Data are considered to be in agreement with the hypothesis that the effect induced by both demethylating agents is an epigenetic inheritable modification leading to a damage proneness of the cells affected. 4-25
Central Bohemia, Prague, Czech Republic, ~ Institute of Occupational Health, Helsinki, Finland Comet assay (SCGE) is powerful method for studying DNA strand breaks and alkali labile sites in DNA supercoil. The method was used to determine damage in human lymphocytes after exposure to potential carcinogen 1,3-butadien (1,3-BD). The group of donors consisted of exposed (n = 19) and control (n = 19) subjects from 1,3-BD production at Kau~uk Kralupy plant. Exposure to 1,3-BD during working shift was determined by personal monitors. Exposure of 2 exposed and 11 control subjects was lower than detection limit. Median of exposure for the control group was 6.5 × 10 3 (range 4.5 × 10 3-0.16) and for the exposed subjects 0.35 (3.3 x 10-3-21) ppm of 1.3-BD ( p > 0.001). Ambient air concentration of 1,3-BD at working place was lower than 0.5 ppm (1 mg/m3). Blood was collected at the end of working shift. The Comet assay was performed on lymphocytes frozen after isolation from blood and stored under liquid nitrogen until analysed. Dead cells were scored in each thawed sample (trypan blue exclusion), 100 cells per person were scored on image analyzer. 5 comet parameters were evaluated for each individual. We did not find significant differences between exposed and control groups for any of the comet parameters. Although the exposure was low, analysis of variance resulted in a significant effect of personal exposure on percentage of DNA in tail of the comet images ( p = 0.02). The results indicate, that 1,3-BD exposure lower than 1 ppm does not induce significant damage to DNA determined by tail length and tail moment. 4-26
Damage of DNA after occupational exposure to 1,3-butadien by the comet assay
Exposure to genotoxic compounds in air pollution. DNA- and protein adducts as markers of exposure and influence of GST~ genotype
K. Peterkovfi, K. Peltonen ", R. Srfim; Laboratory of Genetic Ecotoxicology, Regional Inst. of Hygiene of
P. Sabro, H. Okkels, A.B. Vestergaard, H. Autrup; Department of Environmental and Occupational