RESUMO
The influence of green tea polyphenols (GTP) on the formation of DNA strand breaks (DNA-SB) and lipid peroxidation products (LPP) in cultured human lung cells (A 549) exposed to different oxidants was investigated. Cells were pretreated with GTP for 2 h and then exposed to cigarette smoke solution, H2O2 or FeCl3 for 30 min. After exposure, the cells were analyzed for DNA-SB, LPP, and viability. In addition, the effects of GTP added directly to the incubation mixtures during exposure were examined, using the same end points. It appeared that pretreatment with GTP inhibited both cigarette smoke- and H2O2-induced DNA breakage; i.e., following exposure to cigarette smoke or H2O2, the fraction of DNA passing through a microfilter increased significantly in cells not subjected to GTP, but this effect was prevented or inhibited in GTP-treated cells. Pretreatment with GTP also reduced the overall toxicity of H2O2 as determined by cell growth after exposure. Moreover, addition of GTP during exposure reduced both cigarette smoke- and H2O2-induced DNA breakage as well as formation of LPP after exposure to Fe3+. These results indicate that GTP inhibit the formation of DNA-SB in cells exposed to oxidants. It is possible that this ability to GTP to inhibit DNA-SB formation might contribute to the antitumorogenic properties of green tea.
Assuntos
Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Dano ao DNA , Flavonoides , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Fenóis/isolamento & purificação , Fenóis/farmacologia , Polímeros/isolamento & purificação , Polímeros/farmacologia , Chá/química , Linhagem Celular , Cloretos , Compostos Férricos/toxicidade , Radicais Livres/metabolismo , Humanos , Peróxido de Hidrogênio/toxicidade , Peroxidação de Lipídeos/efeitos dos fármacos , Neoplasias/prevenção & controle , Oxidantes/toxicidade , Plantas Tóxicas , Polifenóis , Espécies Reativas de Oxigênio/metabolismo , Fumaça/efeitos adversos , NicotianaRESUMO
The number of children with asthma is rising. This is shown by a study of medically diagnosed asthma in a cohort of children born in 1990 in a well defined and limited region. The medical records from all of the health centres in primary health care, privately practising paediatricians and relevant child clinics in the region were examined when the children were 7 years old. The results showed that 10.9% of the children had been diagnosed with asthma. The percentage of children with asthma was highest (14.2%) among boys living in a city environment. Comparison with a similar follow-up study in the same region concerning children born in 1975 showed that the percentage of children with asthma doubled during a period of just over a decade.