Giustarini D.,University of Siena |
Galvagni F.,University of Siena |
Tesei A.,Bioscience Laboratory |
Farolfi A.,Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori |
And 7 more authors.
Free Radical Biology and Medicine
The analysis of the global thiol-disulfide redox status in tissues and cells is a challenging task since thiols and disulfides can undergo artificial oxido-reductions during sample manipulation. Because of this, the measured values, in particular for disulfides, can have a significant bias. Whereas this methodological problem has already been addressed in samples of red blood cells and solid tissues, a reliable method to measure thiols and disulfides in cell cultures has not been previously reported. Here, we demonstrate that the major artifact occurring during thiol and disulfide analysis in cultured cells is represented by glutathione disulfide (GSSG) and S-glutathionylated proteins (PSSG) overestimation, due to artificial oxidation of glutathione (GSH) during sample manipulation, and that this methodological problem can be solved by the addition of N-ethylmaleimide (NEM) immediately after culture medium removal. Basal levels of GSSG and PSSG in different lines of cultured cells were 3-5 and 10-20 folds higher, respectively, when the cells were processed without NEM. NEM pre-treatment also prevented the artificial reduction of disulfides that occurs during the pre-analytical phase when cells are exposed to an oxidant stimulus. In fact, in the absence of NEM, after medium removal, GSH, GSSG and PSSG levels restored their initial values within 15-30 min, due to the activity of reductases and the lack of the oxidant. The newly developed protocol was used to measure the thiol-disulfide redox status in 16 different line cells routinely used for biomedical research both under basal conditions and after treatment with disulfiram, a thiol-specific oxidant (0-200 μM concentration range). Our data indicate that, in most cell lines, treatment with disulfiram affected the levels of GSH and GSSG only at the highest concentration. On the other hand, PSSG levels increased significantly also at the lower concentrations of the drug, and the rise was remarkable (from 100 to 1000 folds at 200 μM concentration) and dose-dependent for almost all the cell lines. These data support the suitability of the analysis of PSSG in cultured cells as a biomarker of oxidative stress. © 2015 Elsevier Inc. Source
Cavallo D.,Research Area |
Casadio V.,Bioscience Laboratory |
Bravaccini S.,Bioscience Laboratory |
Iavicoli S.,Research Area |
And 8 more authors.
BioMed Research International
The aim of the present study was to identify sensitive and noninvasive biomarkers of early carcinogenic effect at target organ to use in biomonitoring studies of workers at risk for previous occupational exposure to potential carcinogens. Standard urine cytology (Papanicolaou staining test), comet assay, and quantitative telomerase repeat amplification protocol (TRAP) assay were performed in 159 ex-rubber workers employed in tyres production and 97 unexposed subjects. In TRAP positive cases, a second level analysis using FISH (Urovysion) was done. Cystoscopy results were available for 11 individuals whose 6 FISH/TRAP/comet positive showed in 3 cases a dysplastic condition confirmed by biopsy, 1 comet positive resulted in infiltrating UBC to the biopsy and with hyperplasia and slight dysplasia to the urinary cytology, 1 comet positive resulted in papillary superficial UBC to the biopsy, 1 FISH/TRAP positive showed a normal condition, and 2 TRAP positive showed in one case a phlogosis condition. The results evidenced good concordance of TRAP, comet, and FISH assays as early biomarkers of procarcinogenic effect confirmed by the dysplastic condition and UBC found by cystoscopy-biopsy analysis. The analysis of these markers in urine cells could be potentially more accurate than conventional cytology in monitoring workers exposed to mixture of bladder potential carcinogens. © 2014 Delia Cavallo et al. Source