A prospective case-control study on the evaluation of oxidative stress in renal stone formers

Association of increased oxidative stress (OS) with the pathophysiology of renal stone formation has not been explored greatly in the field of urolithiasis. In this prospective case-control study, we measured 24-h urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in patients with urolithiasis and compared them with matched healthy controls. We also measured 24-h urinary uric acid, calcium, oxalate, and citrate levels in patients with renal stone disease and studied their relation with urinary 8-OHdG levels. Seventy-five cases of renal stone disease and 75 well-matched controls were included. Median 24-h urinary 8-OHdG levels were significantly higher in cases compared to controls (7.6 vs. 3.7 µg/g of creatinine; p < 0.000). Receiver-operating curve (ROC) analysis for 8-OHdG between cases and controls revealed an area under the curve of 0.90. At 8-OHdG (µg/g of creatinine) value of 5 or more, a sensitivity and a specificity of 84% each were obtained. A positive correlation between 8-OHdG (µg/g of creatinine) and 24-h urinary oxalate level was noted (r = 0.461, p = 0.000). No correlation between 8-OHdG (µg/g of creatinine) and other variables was noted. On multivariate linear regression analysis, we noted 24-h urinary oxalate levels to be an independent predictor of urinary 8-OHdG levels. OS is significantly higher in patients with renal stone diseases compared to healthy controls. Urinary oxalate levels were significantly correlated with urinary 8-OHdG levels.

Benzo(a)pyrene, an Active Product of Cigarette Smoke, Role in PLA2 Isoforms Activation in Colon Cancer

Background and aim: One of the active combustion product of cigarette smoke, Benzo[a]pyrenes, role in pulmonary cancer is clearly understood. However, its role in gastrointestinal cancer including colon cancer is not clearly understood. Methods: In this study, benzo(a)pyrenes was treated to colon cells to evaluate its role in cell viability, cellular ROS, and gene expression of various PLA2 isoforms was evaluated by FACS and PCR. The identified PLA2 was silenced at the gene level to evaluate its role in cell viability and ROS generation. Results: B(a)P treatment at 1 µg/mL for 48 h to HCT-15 male colon cells significantly reduced the cell viability without affecting HT-29 female colon cells. Higher doses and longer treatment duration with B(a)P showed that female colon cells were highly sensitive than male colon cells. Annexin-V/PI staining for preapoptotic detection showed that B(a)P treatment increased the apoptosis in both the cell types in a concentration and time-dependent manner. The cytosolic ROS (cROS) and superoxide radical (SOR) formation in the female colon cells was significantly higher than male colon cells unlike the mitochondrial ROS (mtROS) production which was significantly higher in male colon cells. Treatment with B(a)P significantly upregulated the IID and IVA PLA2 isoform groups in HCT-15 male colon cells, whereas IB was upregulated in HT-29 female colon cells among the various PLA2 isozyme gene studied (IB, IID, III, IVA, IVB, IVC, VI, X, aiPLA2 and iPLA2). Gene silencing experiments targeting PLA2 IID and IVA in the HCT-15 male colon cells and IB in HT-29 female colon cells showed no effect with B(a)P treatment on the cell proliferation, apoptosis, membrane integrity and free radicals (ROS, mtROS, and SOR) generation. Conclusion: Targeting specific PLA2 isozymes in a cell-specific manner abolished the B(a)P-induced PLA2-mediated oxidative damage–related signaling pathways.