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INTRODUCTION: Introduction Patients with Chronic renal Disease (CRD) often have cardiovascular disease that is the main cause of morbidity and mortality. Oxidative stress and a subclinical inflammation are crucial factors in its development. The aim of this study was to asses the oxidation of the main molecular lines in patients with advanced renal disease without dialysis and to determinate the best biomarker to asses this stress. PATIENTS AND METHODS: We performed an observational study to measure the most important oxidative biomarkers in 32 patients with stage 4 CRD (MDRD = 22.1 +/- 1.08 ml/min) compared with the values obtained in a control group. In peripheral lymphocytes we measured, the lipid peroxidation by Malondialdehyde (MDA) and F2 Isoprostanes in plasma; protein oxidation by glutathione oxidized/reduced ratio (GSSG/GSH) in peripheral lymphocytes and protein carbonyls in plasma and the oxidative damage in genetic material by modified nucleotide base 8-deoxiguanosina oxo -(8-oxo-dG), after isolating nuclear and mitochondrial DNA. We also studied the antioxidant defenses with superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GSR) and catalase (CAT) in peripheral lymphocytes. We studied the correlation between oxidative stress and the renal function and oxidative stress and co-morbidity factors. RESULTS: All biomarkers showed important differences in comparison with the control subjects. 821.89 +/- 300.47 ng/ml vs. 270 (95.66) * ng/ml (p < 0.000), MDA 0.11 (0.11) * vs. 0.7 +/- 0.31 nmol/mg prot (p <0.000). GSSG / GSH: 6.89 +/- 1.91 vs. 1.39 +/- 0.75 (p <0.000), protein carbonyls: 7.41 +/- 0.84 vs. 3.63 (1.12) *. Nuclear 8-oxo-dG 7.88 (2.32) vs. 2.96 (1.78) * mitochondrial 8-oxo-dG: 15.73 +/- 2.28 vs. 13.85 +/- 1.44 (p <0.05). The Antioxidant enzymes also showed differences. Nuclear 8-oxo-dG demonstrated an important relationship with the rest of biomarkers, homocysteine (r = 0.305, p <0.05), lipoprotein (a) (r = 0.375, p <0.01), mitochondrial 8-oxo-dG (r = 0.411, p <0.05), GSSH/GSH (r = 0.595, p <0.001) and protein carbonyls (r = 0.489, p <0.05). There was an inverse correlation with total protein (r = -0.247, p <0.01), GSH (r = -0.648, p <0.000), GSR (r = -0.563, p <0.001) and SOD (r = -0.497, p <0.000). We did not find any correlation between these parameters and renal function. The presence of diabetes or the treatment with statins did not showed significant differences. * Median (Interquartile range). CONCLUSION: There is an important oxidative stress in patients with advanced renal disease, probably established during early stages of disease. Of the studied parameters, the nuclear 8-oxo-dG is the best marker for oxidative stress in CRD.
Assuntos
Nefropatias/metabolismo , Estresse Oxidativo , Idoso , Doença Crônica , Progressão da Doença , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Aplidin is an antitumor agent in phase II clinical trials that induces apoptosis through the sustained activation of Jun N-terminal kinase (JNK). We report that Aplidin alters glutathione homeostasis increasing the ratio of oxidized to reduced forms (GSSG/GSH). Aplidin generates reactive oxygen species and disrupts the mitochondrial membrane potential. Exogenous GSH inhibits these effects and also JNK activation and cell death. We found two mechanisms by which Aplidin activates JNK: rapid activation of Rac1 small GTPase and downregulation of MKP-1 phosphatase. Rac1 activation was diminished by GSH and enhanced by L-buthionine (SR)-sulfoximine, which inhibits GSH synthesis. Downregulation of Rac1 by transfection of small interfering RNA (siRNA) duplexes or the use of a specific Rac1 inhibitor decreased Aplidin-induced JNK activation and cytotoxicity. Our results show that Aplidin induces apoptosis by increasing the GSSG/GSH ratio, a necessary step for induction of oxidative stress and sustained JNK activation through Rac1 activation and MKP-1 downregulation.