Simvastatin treatment prevents oxidative damage to DNA in whole blood leukocytes of dyslipidemic type 2 diabetic patients.

Type 2 diabetes (T2D) is associated with increased oxidative stress as indicated by elevated levels of lipid peroxidation and protein oxidation products. Since reactive oxygen species (ROS) can cause damage to biological macromolecules including DNA, this study investigated oxidative damage to DNA using the alkaline (pH > 13) comet assay in peripheral whole blood leukocytes sampled from 15 dyslipidemic T2D patients treated with simvastatin (20 mg/day), 15 dyslipidemic T2D patients not treated with simvastatin, 20 non-dyslipidemic T2D patients, and 20 healthy individuals (controls). Our results showed a greater DNA migration in terms of damage index (DI) (p < 0.01) in the dyslipidemic T2D patients not treated with statin (DI = 67.70 +/- 10.89) when compared to the dyslipidemic T2D patients under statin treatment (DI = 47.56 +/- 7.02), non-dyslipidemic T2D patients (DI = 52.25 +/- 9.14), and controls (DI = 13.20 +/- 6.40). Plasma malondialdehyde (MDA) and C-reactive protein (CRP) levels were also increased and total antioxidant reactivity (TAR) and paraoxonase activity (PON1) decreased in non-dyslipidemic T2D patients and dyslipidemic T2D non-treated with simvastatin. We also found that DI was inversely correlated with TAR (r = -0.61, p < 0.05) and PON1 (r = -0.67, p < 0.01). In addition, there was a significant positive correlation between DI and CRP (r = 0.80, p < 0.01). Our results therefore indicate that simvastatin treatment plays a protective role on oxidative damage to DNA in dyslipidemic T2D patients probably reflecting a general decrease in oxidative stress in these patients.

Evidence that DNA damage is associated to phenylalanine blood levels in leukocytes from phenylketonuric patients.

Phenylketonuria (PKU) is an inborn error of phenylalanine (Phe) metabolism, biochemically characterized by the accumulation of Phe and its metabolites in blood and tissues of affected patients. Treatment for PKU consists of a protein restricted diet supplemented with a mixture containing essential amino acids (other than Phe) and micronutrients. In recent years several authors have studied the pathomechanisms of the disease and demonstrated the existence of lipid and protein oxidative damage in PKU patients. In this work we investigated the in vivo and in vitro effects of Phe on DNA damage determined by the alkaline comet assay using silver staining and visual scoring. We found a dose-dependent effect of Phe on DNA damage in leukocytes from normal individuals incubated with different concentrations of Phe. Additionally, by analyzing blood leukocytes from two groups of treated PKU patients based on their blood Phe levels, we verified that the DNA damage index was significantly higher in PKU patients with high Phe blood levels (DI = 68.2 +/- 12.3), compared to well-treated patients and the control group (healthy individuals). Furthermore, well-treated PKU patients had greater DNA damage (DI = 44.9 +/- 7.6) relatively to controls (DI = 12.7 +/- 4.1). Our present in vitro and in vivo findings indicate that DNA damage occurs in peripheral blood from PKU patients and is associated to Phe blood levels.