Oxidative stress in abetalipoproteinemia patients receiving long-term vitamin E and vitamin A supplementation

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Abstract
Background: Patients with abetalipoproteinemia develop progressive ataxic neuropathy and retinopathy that are thought to be due, in part, to oxidative damage resulting from deficiencies of vitamins E and A. Objective: The goal was to determine the degree of oxidative stress in abetalipoproteinemia patients who had received vitamin E (100 mg/kg) and vitamin A (10 000-15 000 IU/d) since infancy. Design: Ten patients aged 3-25 y were studied. Assessed were plasma carbonyl concentrations as a marker of oxidative damage to proteins; total plasma oxidizability, which was used to evaluate the susceptibility of plasma lipoproteins to oxidation; and cyclic voltammetry, which represents the overall reducing and antioxidant capacity stemming from low-molecular-weight antioxidants in plasma. Results: Concentrations of plasma carbonyls did not differ significantly between patients and control subjects (x̄ ± SE: 0.5670 ± 0.031 and 0.5039 ± 0.0134 nmol/mg protein, respectively). The lag phase of plasma oxidizability was 28.03 ± 3.16 min in the patients and 24.0 ± 2.79 min in healthy subjects in whom oxidizability of isolated HDL was measured (NS). Cyclic voltammetry showed a peak potential of 330 ± 8.3 mV in all samples studied, denoting that the same antioxidants were present in the plasma of the patients and the control subjects. The anodic current of the samples, a measure of the concentration of hydrophilic low-molecular-weight antioxidants, was 5.227 ± 0.25 and 5.38 ± 0.20 μA in the patients and the control subjects, respectively (NS). Conclusion: Enhanced oxidative stress is not apparent in the plasma of abetalipoproteinemia patients receiving long-term supplementation with vitamins E and A.