Search

Previous studies demonstrated the presence of unknown direct-acting ethylating agents arising from cigarette smoke. We hypothesized that such agents would also lead to ethylation of guanine in DNA followed by depurination/repair and excretion of N7-ethylguanine (N7-EtG) in urine. In this study, a highly specific and sensitive liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method was firstly developed for measuring urinary N7-EtG. With the use of an isotope internal standard (15N5-N7-EtG) and on-line enrichment techniques, the detection limit of this method was estimated as 0.59 pg/ml (0.33 pmol) on-column. This method was then applied to measure urinary samples obtained from 35 non-smokers and 32 smokers with dietary control. The results showed that the mean urinary levels of N7-EtG were 85.5 ± 105 and 28.1 ± 19.4 pg/mg creatinine for smokers and non-smokers, respectively. Smokers had about three times higher level of N7-EtG than non-smokers (P < 0.005). It was further noted that the urinary level of N7-EtG was significantly associated with cotinine for smokers (r = 0.49, P < 0.005). Taken together, this is the first study that demonstrated the presence of N7-EtG in urine, and that cigarette smoke was highly responsible for the increased urinary excretion of N7-EtG. This non-invasive measurement of urinary N7-EtG would be useful for the surveillance of ethylating agent exposure and its associated cancer risk in the future. [ABSTRACT FROM AUTHOR]

The article presents a study on the quantitative analysis of blood betel quid alkaloids and urinary 8-hydroxydeoxyguanosine (8-OH-dg) in human, along with its correlation in betel chewing habits. The study developed a liquid chromatography-tandem mass spectrometry method to examine the quantity of arecoline and arecaidine, and showed the correlation of betel quid on drawing blood and arecoline. It reveals that serum arecoline and arecaidine were measurable and good indicators of betel quid use.