[Experimental study on lung injury and cell cycle changes in mice induced by bitumen fume].
OBJECTIVE
To investigate the carcinogenic and mutagenic mechanism of bitumen fume.


METHODS
The experimental mice were forced to inhale the bitumen fume at different exposure level (55 mg/m(3), 165 mg/m(3)) and in different time (30 days, 60 days). The pathological changes of the lung tissue in mice were observed with H.E staining. The content of the DNA in the lung tissue of mice and the cell circles were determined with flow cytometry.


RESULTS
The lesion of the lung tissue in mice comprised the atypical hyperplasia of different levels and the carcinoma in situ with the increase of the containment time and dosage; the cycle index was changed: the number of the G 1 phase cells was decreased, the S phase was retarded, the cells entering the G 2/S phase were decreased, the cell proliferation index (P I) was increased and the heteroploid DNA index (DI) was increased (P < 0.05). The cell index in the 55 mg/m(3) group and the 165 mg/m(3) group was higher than that in the control group when the containment time was same. The heteroploid DNA index (DI) in the 55 mg/m(3) group was significantly higher than that in the 165 mg/m(3) group (P < 0.05 or P < 0.01). When the containment dosage was same, the DI in the 60 days treatment group (1.16 +/- 1.51 x 10(-2), 1.20 +/- 2.3 x 10(-2)) was all significantly higher than those in the 30 days treatment group (1.14 +/- 8.8 x 10(-2), 1.16 +/- 1.47 x 10(-2)) (P < 0.05).


CONCLUSIONS
The precancerous lesion in the lung tissue of the mice induced by the bitumen fume may be related with the changes of the cell cycle.
Liu
Xiao-xia
XX
Department of Occupational Medicine, People's Hospital of Gansu Province, Lanzhou 730000, China.
Guo
Xiang-yun
XY
D000818:Animals; D002273:Carcinogens / Q000633:toxicity*; D002453:Cell Cycle / Q000187:drug effects*; D004247:DNA / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D005260:Female; D005434:Flow Cytometry; D006838:Hydrocarbons / Q000633:toxicity*; D008168:Lung / Q000187:drug effects / Q000473:pathology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D011230:Precancerous Conditions / Q000139:chemically induced* / Q000473:pathology
D002273:Carcinogens; D006838:Hydrocarbons; C006647:asphalt; D004247:DNA