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- Andersson, Maria, et al.
(författare)
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Interindividual differences in initial DNA repair capacity when evaluating H2O2-induced DNA damage in extended-term cultures of human lymphocytes using the comet assay
- 2007
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Ingår i: Cell Biology and Toxicology. - : Springer Science and Business Media LLC. - 0742-2091 .- 1573-6822. ; 23:6, s. 401-411
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that extended-term cultures of human lymphocytes could be used as a complement to cell lines based on transformed cells when testing the genotoxicity of chemicals. To investigate whether the pattern of induced DNA damage and its subsequent repair differs significantly between cultures based on different blood donors, hydrogen peroxide (H2O2)-induced DNA damage was measured in cultures from four different subjects using the comet assay. The DNA damage was significantly increased in all cultures after 10 min exposure to 0.25 mmol/L H2O2, and there was a significant decrease in the H2O2-induced DNA damage in all cultures after 30 min of DNA repair. The level of damage varied between the different donors, especially after the repair. Using PCR and DNA sequencing, exon 5 of the p53 gene was sequenced in the lymphocytes from the donors with the lowest and highest residual damage. No such mutation was found. Mouse lymphoma L5178Y cells carrying the p53 mutation in exon 5 were included as a reference. These cells were found to be less sensitive toward the H2O2-induced DNA damage, and they were also found to have a rather low DNA repair capacity. The demonstrated variation in H2O2-induced DNA damage and DNA repair capacity between the cultures from the different subjects may be important from a risk assessment perspective, but is obviously not of decisive importance when it comes to the development of a routine assay for genotoxicity.
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| 2. |
- Axelsson, V, et al.
(författare)
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Glutathione intensifies gliotoxin-induced cytotoxicity in human neuroblastoma SH-SY5Y cells.
- 2006
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Ingår i: Cell Biology and Toxicology. - : Springer Science and Business Media LLC. - 0742-2091 .- 1573-6822. ; 22:2, s. 127-36
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Tidskriftsartikel (refereegranskat)abstract
- Gliotoxin is a fungal second metabolite produced by diverse species that can be found in compost, stored crops, moist animal feed and sawdust. The role of glutathione in gliotoxin-induced toxicity was studied in order to elucidate the toxic mechanisms leading to neurite degeneration and cell death in differentiated human neuroblastoma (SH-SY5Y) cells. After 72 h of exposure to gliotoxin, moderate cytotoxicity was induced at 0.1 micromol/L, which was more severe at higher concentrations. A reduction in the number of neurites per cell was also observed. By decreasing the level of intracellular glutathione with L: -buthionine-sulfoxamine (BSO) a specific inhibitor of glutathione synthesis, the cytotoxic effect of gliotoxin was significantly attenuated. The gliotoxin-induced cytotoxicity was also slightly reduced by the antioxidant vitamin C. However, the neurite degenerative effect was not altered by BSO, or by vitamin C. A concentration-dependent increase in the ratio between oxidized and reduced forms of glutathione, as well as the total intracellular glutathione levels, was noted after exposure to gliotoxin. The increase of glutathione was also reflected in western blot analyses showing a tendency for the regulatory subunit of gamma-glutamylcysteine synthetase to be upregulated. In addition, the activity of glutathione reductase was slightly increased in gliotoxin-exposed cells. These results indicate that glutathione promotes gliotoxin-induced cytotoxicity, probably by reducing the ETP (epipolythiodioxopiperazine) disulfide bridge to the dithiol form.
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