Direct determination of nucleosides in the urine of patients with breast cancer using column-switching liquid chromatography-tandem mass spectrometry
Authors: Cho, Sung-Hee; Jung, Byung Hwa; Lee, Sang Hee; Lee, Won-Yong; Kong, Gu; Chung, Bong Chul
We developed an analytical method for a simple, sensitive and simultaneous determination of oxidized nucleosides in urine using column-switching liquid chromatography-electrospray/tandem mass spectrometry (LC-ESI/MS/MS). We connected two columns through a six-way switching valve and effectively separated nucleosides in the urine from the interference by column-switching liquid chromatography. We monitored separated nucleosides using positive ionization tandem mass spectrometry in selective reaction monitoring (SRM) mode. The calibration ranges of nucleosides were 0.2-100 nmol/mL. The linearity of the method was 0.994-0.999, and the limits-of-detection (LOD) at a signal-to-noise (S/N) ratio of 3 were 0.1-0.2 nmol/mL. The coefficients of variation were in the range 2.28-11.74% for within-day variation and 4.36-11.15% for day-to-day variation, respectively. To explore the relationship between breast cancer and the nucleosides level in human urine, we measured the concentrations of nucleosides in female patients with breast cancer (n = 30) and in normal female subjects (n = 30). The concentration of nucleosides was significantly increased in patients with breast cancer when compared with the normal controls (1-methyladenosine; p < 0.005, N-2,N-2-dimethylguanosine; p < 0.01, 5-hydroxymethyl-2'-deoxyuridine; p < 0.001, 8-hydroxy-2-deoxyguanosine; p < 0.001). Therefore, the elevated levels of nucleosides could be used as an important biomarker for breastcancer research. Copyright (c) 2006 John Wiley & Sons, Ltd.
The Exacerbation of Aging and Oxidative Stress in the Epididymis of Sod1 Null Mice
Authors: Noblanc, Anais; Klaassen, Alicia; Robaire, Bernard
There is growing evidence that the quality of spermatozoa decreases with age and that children of older fathers have a higher incidence of birth defects and genetic mutations. The free radical theory of aging proposes that changes with aging are due to the accumulation of damage induced by exposure to excess reactive oxygen species. We showed previously that absence of the superoxide dismutase 1 (Sod1) antioxidant gene results in impaired mechanisms of repairing DNA damage in the testis in young Sod1(-/-) mice. In this study, we examined the effects of aging and the Sod(-/-) mutation on mice epididymal histology and the expression of markers of oxidative damage. We found that both oxidative nucleic acid damage (via 8-hydroxyguanosine) and lipid peroxidation (via 4-hydroxynonenal) increased with age and in Sod1(-/-) mice. These findings indicate that lack of SOD1 results in an exacerbation of the oxidative damage accumulation-related aging phenotype.