in order to evaluate endogenous nitrosation in the oral cavity of chewers of betel quid with tobacco ( bqt ) or without tobacco ( bq ) , saliva samples were collected from healthy male volunteers after chewing sequentially ( i ) unmodified bqt or bq , ( ii ) bqt or bq to which proline has been added , and ( iii ) bqt or bq to which proline and ascorbic acid had been added .
C0226896
oral cavity
C0024888
chewing