title: Oxidative DNA damage induced by silica in vivo.
abstract: Occupational exposure to silica has often been associated with the development of pulmonary fibrosis and, occasionally, lung cancer. Their development may be mediated by oxidant-induced cellular injury. The short- and long-term effects of a single intratracheal instillation of silica in rats (10 mg/200 microliters/saline per rat) was assessed by measuring 8-hydroxy-2'-deoxyguanosine (oh8dG) levels in lung tissue and peripheral blood leukocytes. Cell differentials, reduced glutathione (GSH), and superoxide dismutase (SOD), lipid peroxide, and total phospholipids in peripheral blood and/or bronchoalveolar lavage fluid (BALF) were also measured. The pulmonary oh8dG levels increased approximately 2.24- 2.86-fold from 1 to 5 days after exposure to silica. It was still elevated 1 and 4 weeks after installation, but the difference was no longer statistically significant. The oh8dG levels in peripheral blood leukocytes were never significantly different, but they were generally higher than in the controls. The low SOD levels in the BALF of exposed rats in the early stage and the higher GSH levels in the late stage may represent protective reactions against the generation of oxygen species. A significant increase in oh8dG levels in lung tissue suggested the possible carcinogenicity of silica.
authors.affiliation: Department of Hygiene and Public Health, Tokyo Women's Medical College, Japan
authors.forename: Y
authors.initials: Y
authors.lastname: Yamano
authors.forename: J
authors.initials: J
authors.lastname: Kagawa
authors.forename: T
authors.initials: T
authors.lastname: Hanaoka
authors.forename: T
authors.initials: T
authors.lastname: Takahashi
authors.forename: H
authors.initials: H
authors.lastname: Kasai
authors.forename: S
authors.initials: S
authors.lastname: Tsugane
authors.forename: S
authors.initials: S
authors.lastname: Watanabe
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000166:cytology; D002454:Cell Differentiation / Q000187:drug effects; D004249:DNA Damage; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000378:metabolism; D004195:Disease Models, Animal; D005978:Glutathione / Q000097:blood / Q000378:metabolism; D007962:Leukocytes / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008168:Lung / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D008175:Lung Neoplasms / Q000139:chemically induced / Q000209:etiology; D008297:Male; D016273:Occupational Exposure; D018384:Oxidative Stress; D010743:Phospholipids / Q000097:blood / Q000378:metabolism; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000209:etiology; D051381:Rats; D017208:Rats, Wistar; D012822:Silicon Dioxide / Q000008:administration & dosage / Q000633:toxicity*; D013047:Specific Pathogen-Free Organisms; D013482:Superoxide Dismutase / Q000097:blood / Q000187:drug effects / Q000378:metabolism; D014132:Trachea / Q000187:drug effects
chemical_list: D010743:Phospholipids; D012822:Silicon Dioxide; D000080242:8-Hydroxy-2'-Deoxyguanosine; D013482:Superoxide Dismutase; D003849:Deoxyguanosine; D005978:Glutathione