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High-performance liquid chromatography (HPLC) was combined with electrospray ionization tandem mass spectrometry (ESI-MS/MS) to develop a sensitive and selective method for the quantitative measurement of N(7)-(2-hydroxyethyl)guanine (N(7)-HEG) adducts in DNA obtained from ethylene oxide-exposed biological samples. Selected reaction monitoring (SRM) was used as the detection mode while the fragmentation product ion at m/z 152 generated from the precursor protonated N(7)-HEG (m/z 196) was monitored. The detection limits for N(7)-HEG were estimated by twofold serial dilution and determined to be 4 fmol in neat standard solution and 16 fmol when a matrix effect is considered. When the mass spectrometer was operated in the selected ion monitoring mode using only the first quadrupole (without MS/MS function), the detection limits increased to 128 fmol and 1 pmol (when matrix effect is considered), respectively. A good linear correlation (R(2) = 0.999) was observed for signal intensities obtained by injecting 16 fmol--33 pmol of N(7)-HEG into the HPLC/ESI-MS/MS system. Hep G2 cells were incubated for 8 h with medium containing various concentrations of ethylene oxide (ranging from 0.05 to 5.0 mM). A dose-response relationship was established, indicating that the adduct formation increases with the exposure level. The method shows potential, although the detection limit needs to be lowered for practical applications, for use in monitoring N(7)-HEG formation in other biological systems.

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Cloud computing was a cloud technology pioneered by Amazon for a long time due to its software technology that is based on the online shopping platform. After Google, Microsoft also follow up, and this technology, in fact, already exists in our lives, and applications continue to expand, become an integral part of life. With the rapid development of the Internet and the demand for high-speed computing of mobile devices, the simplest cloud computing technology has been widely used in online services, such as "search engine, webmail," and so on. Users can get a lot of information by simply entering a simple instruction. Further cloud computing is not only for data search and analysis function, but also can be used in the biological sciences, such as: analysis of cancer cells, analysis of DNA structure, gene mapping sequencing; in the future more Smart phone, GPS and other mobile devices through the cloud computing to develop more application service.