By a News Reporter-Staff News Editor at Life Science Weekly -- Investigators publish new report on DNA Research. According to news reporting out of Chiayi, Taiwan, by NewsRx editors, research stated, "Evidence showed that ethylating agents are contained in cigarette smoke, which damage DNA producing ethylated DNA adducts, including N-3-ethyladenine (3-EtAde) and N-7-ethylguanine (7-EtGua). These two ethylpurines can be depurinated spontaneously and be repaired by enzymes and they have been detected in human urine."
Our news journalists obtained a quote from the research from National Chung Cheng University, "In this study, a highly specific and sensitive assay based on stable isotope dilution nanoflow liquid chromatography nanospray ionization tandem mass spectrometry (nanoLC-NSI/MS/MS) was used to measure 3-EtAde and 7-EtGua in human salivary DNA. These ethylpurines were released from DNA by neutral thermal hydrolysis and then enriched by a solid-phase extraction column before nanoLC-NSI/MS/MS analysis. The detection limits (S/N >= 3) of 3-EtA and 7-EtG were 15 fg (92 amol) and 10 fg (56 amol), respectively, injected on-column. The lower quantification limits of 3-EtAde and 7-EtGua were both 100 fg, i.e. 620 and 560 amol, respectively, corresponding to 9.4 and 8.6 adducts in 10(9) normal nucleotides, respectively, starting with as little as 20 mu g of DNA isolated from an average of 3 mL of saliva. The mean (+/- SD) levels of 3-EtAde in 15 smokers and 15 nonsmokers were 12.6 +/- 7.0 and 9.7 +/- 5.3 in 10(8) normal nucleotides, respectively, while those of 7-EtGua were 14.1 +/- 8.2 and 3.8 +/- 2.8 in 10(8) normal nucleotides in smokers and nonsmokers, respectively. Levels of 7-EtGua, but not 3-EtAde, were statistically significantly higher in smokers than in nonsmokers (p < 0.0001). Furthermore, salivary 7-EtGua levels are significantly correlated with the number of cigarettes smoked per day as well as with the smoking index."
According to the news editors, the research concluded: "This highly specific and sensitive stable isotope dilution nanoLC-NSI/MS/MS assay might be feasible in measuring 7-EtGua in human salivary DNA as a noninvasive biomarker for DNA damage induced by cigarette smoking."
For more information on this research see: Noninvasive measurement of smoking-associated N-3-ethyladenine and N-7-ethylguanine in human salivary DNA by stable isotope dilution nanoflow liquid chromatography-nanospray ionization tandem mass spectrometry. Toxicology Letters, 2014;225(1):27-33. Toxicology Letters can be contacted at: Elsevier Ireland Ltd, Elsevier House, Brookvale Plaza, East Park Shannon, Co, Clare, 00000, Ireland. (Elsevier - www.elsevier.com; Toxicology Letters - www.elsevier.com/wps/product/cws_home/505519)
Our news journalists report that additional information may be obtained by contacting H.J.C. Chen, Natl Chung Cheng Univ, Dept. of Chem & Biochem, Chiayi 62142, Taiwan (see also DNA Research).
Keywords for this news article include: Asia, Chiayi, Taiwan, DNA Research
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