國家衛生研究院 NHRI:Item 3990099045/2471

NHRI > National Institute of Environmental Health Sciences > Louis W. Chang(1999-2009) > Periodical Articles > Item 3990099045/2471

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Title:	Quantitative determination of urinary N7-ethylguanine in smokers and non-smokers using an isotope dilution liquid chromatography/tandem mass spectrometry with on-line analyte enrichment
Authors:	Chao, MR;Wang, CJ;Chang, LW;Hu, CW
Contributors:	Division of Environmental Health and Occupational Medicine
Abstract:	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 (N-15(5)-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.
Keywords:	Oncology
Date:	2006-01
Relation:	Carcinogenesis. 2006 Jan;27(1):146-151.
Link to:	http://dx.doi.org/10.1093/carcin/bgi177
JIF/Ranking 2023:	http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=NHRI&SrcApp=NHRI_IR&KeyISSN=0143-3334&DestApp=IC2JCR
Cited Times(WOS):	https://www.webofscience.com/wos/woscc/full-record/WOS:000234219300016
Cited Times(Scopus):	http://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=29744450932
Appears in Collections:	[Louis W. Chang(1999-2009)] Periodical Articles

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