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[Study on silica induced DNA damage and its influence factor].

OBJECTIVE
To detect DNA damage in Chinese Hamster Lung Fibroblast(CHLF) exposed to low doses of silica particles(7.5 - 120.0 micrograms/ml).


METHODS
Comet assay was used to detect DNA damage. The cells were divided into various groups by doses and incubation time of silica particles to observe silica-induced DNA damage; and the influence of hydroxyl radicals and calcium ion in DNA damage by using deferoxamine and verapamil was also studied. The tail lengths of comet were used to measure DNA damage.


RESULTS
The tail lengths were significantly longer in exposed cells, compared to matched controls(P < 0.01), and were increased in a dose-dependent manner from 7.5-120.0 micrograms/ml. The tail lengths of two-hour group were longer than one-hour group. When exposed to 90 micrograms/ml silica particles, 0.5-2.0 mmol/L deferoxamine and 2.5-20.0 micrograms/ml verapamil could attenuate silica-induced DNA damage effectively, their protective effects were increased in a concentration-dependent manner.


CONCLUSION
Small dose of SiO2 could induce CHLF DNA damage. Calcium ion and hydroxyl radical may take part in this process, antioxidant and calcium antagonate may protect SiO2 induced DNA damage.