Reduced protein oxidation in Wistar rats supplemented with marine ω3 PUFAs.

The potential effects of various dietary eicosapentaenoic acid (EPA; 20:5) and docosahexaenoic acid (DHA; 22:6) ratios (1:1, 2:1, and 1:2, respectively) on protein redox states from plasma, kidney, skeletal muscle, and liver were investigated in Wistar rats. Dietary fish oil groups were compared with animals fed soybean and linseed oils, vegetable oils enriched in ω6 linoleic acid (LA; 18:2) and ω3 α-linolenic acid (ALA; 18:3), respectively. Fish oil treatments were effective at reducing the level of total fatty acids in plasma and enriching the plasmatic free fatty acid fraction and erythrocyte membranes in EPA and DHA. A proteomic approach consisting of fluorescein 5-thiosemicarbazide (FTSC) labeling of protein carbonyls, FTSC intensity visualization on 1-DE or 2-DE gels, and protein identification by MS/MS was used for the protein oxidation assessment. Albumin was found to be the most carbonylated protein in plasma for all dietary groups, and its oxidation level was significantly modulated by dietary interventions. Supplementation with an equal EPA:DHA ratio (1:1) showed the lowest oxidation score for plasma albumin, followed in increasing order of carbonylation by 1:2 <2:1 ≈ linseed < soybean. Oxidation patterns of myofibrillar skeletal muscle proteins and cytosolic proteins from kidney and liver also indicated a protective effect on proteins for the fish oil treatments, the 1:1 ratio exhibiting the lowest protein oxidation scores. The effect of fish oil treatments at reducing carbonylation on specific proteins from plasma (albumin), skeletal muscle (actin), and liver (albumin, argininosuccinate synthetase, 3-α-hydroxysteroid dehydrogenase) was remarkable. This investigation highlights the efficiency of dietary fish oil at reducing in vivo oxidative damage of proteins compared to oils enriched in the 18-carbon polyunsaturated fatty acids ω3 ALA and ω6 LA, and such antioxidant activity may differ among different fish oil sources because of variations in EPA/DHA content.

Role of oxidative stress in cardiovascular effects of anemia treatment with erythropoietin in predialysis patients with chronic kidney disease.

BACKGROUND/AIM: Oxidative stress (OS) is involved in left ventricular hypertrophy (LVH). Short-term treatment with erythropoietin (EPO) in chronic kidney disease (CKD) complicated by anemia and LVH is associated with a reduction in left ventricular mass (LVM). We proposed to assess whether the pro-oxidant status of CKD influences these outcomes. METHODS: Predialysis patients (n = 76) with CKD and hemoglobin (Hb) levels < 11 g/dl received EPO for 6 months. The effects of this anemia correction on LVH regression were evaluated using echocardiography. Patients with LVM decrease > 10% were considered "responders" (n = 25) to treatment and those with LVM change < 10% were considered "non-responders" (n = 24). Measurement of OS included plasma and erythrocyte oxidized (GSSG) and reduced (GSH) glutathione, GSH redox ratio (GSSG/GSH), erythrocyte glutathione peroxidase (GPx) and oxidized LDL (Ox- LDL). RESULTS: 49 patients completed the study. With EPO therapy, mean Hb levels increased from 9.9 ± 0.6 to 12.8 ± 1.5 g/ dl (p < 0.0001) and LVM index decreased from 69.2 ± 17.7 to 64.1 ± 19.6 g/m2.7 (p = 0.01). At 6 months, "non-responders" had higher systolic blood pressure, pulse pressure, GSSG and GSH redox ratio and lower GSH than "responders". In multivariate analysis, and following adjustment for confounding variables, systolic blood pressure and GSH redox ratio independently predicted LVH regression. CONCLUSION: Blood pressure and plasma GSH redox ratio (a marker of OS) are important predictors of LVH regression in anemic predialysis patients treated with EPO.

Evaluation of oxidative stress biomarkers in patients with chronic renal failure: a case control study.

BACKGROUND: Oxidative stress is related to several diseases, including chronic renal insufficiency. The disequilibrium in the oxidant-antioxidant balance is the result of several metabolic changes. The majority of studies to-date have evaluated the grade of oxidative stress with a single biomarker, or a very limited number of them. FINDINGS: The present study used several important biomarkers to establish a score relating to oxidative stress status (glutathione S-transferase, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, reduced and oxidized glutathione, thiobarbituric acid reactive substances and hemolysis test). The score of oxidative stress (SOS) was then applied to a group of patients with renal insufficiency not on hemodialysis, and compared to healthy control individuals.The score for patients with chronic renal insufficiency was significantly different from that of the healthy control group (0.62 +/- 1.41 vs. -0.05 +/- 0.94; p < 0.001). The comparison between patients with chronic renal insufficiency and control individuals showed significant differences with respect to changes in the enzymatic antioxidant systems (glutathione S-transferase, glutathione reductase), non-enzymatic antioxidant system (oxidized glutathione) and oxidizability (hemolysis test) indicating significant oxidative stress associated with chronic renal insufficiency. CONCLUSIONS: Patients with chronic renal insufficiency not on hemodialysis are susceptible to oxidative stress. The mechanisms that underlie this status are the consequence of changes in glutathione and related enzymes. The SOS scoring system is a useful biochemical parameter to evaluate the influence of oxidative stress on the clinical status of these patients.

Effect of nut consumption on oxidative stress and the endothelial function in metabolic syndrome.

BACKGROUND & AIMS: Oxidative stress has a key role in atherosclerosis, cancer and other chronic diseases. Some bioactive compounds in nuts have been implicated in antioxidant activities. OBJECTIVE: We assessed how nut consumption affected several markers of oxidation and endothelial function (EF) in metabolic syndrome (MetS) patients. PATIENTS AND METHODS: A randomized, controlled, parallel feeding trial was conducted on 50 MetS adults who were recommended a healthy diet supplemented or not with 30 g of mixed nuts (Nut and Control groups, respectively) every day for 12 weeks. The plasma antioxidant capacity (AC), oxidized LDL (oxLDL), conjugated diene (CD) formation, urine 8-isoprostanes, DNA damage assessed by yield of urine 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), and EF assessed by peripheral artery tonometry (PAT) and biochemical markers, were measured at baseline and the end of the intervention. RESULTS: No significant differences in changes between groups were observed in AC, oxLDL, CD, 8-isoprostanes or EF during the intervention, whereas the reduction in DNA damage was significant in the Nut group compared to Control group (P < 0.001). CONCLUSION: Nut consumption has no deleterious effect on lipid oxidation. The decrease in DNA damage observed in this study could contribute to explain the beneficial effects of regular nut consumption on some MetS features and several chronic diseases.