Abstract
Reactive oxygen species and lipid peroxidation are important factors that contribute to the development of age-related cataract. The study included 130 patients with age-related cataract, 69 of whom were diagnosed with hypertension (HT), 20 with hypertension and type 2 diabetes mellitus (DM), and 41 had no accompanying condition. The following parameters were measured in the serum of the examinees: products of lipid peroxidation malondialdehyde (MDA) and lipofuscin-like fluorophores (LLF), activity of prooxidative enzymes xanthine oxidase (XO) and myeloperoxidase (MPO), antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx), the concentration of thiol groups, and the ferric reducing activity of plasma. The activity of prooxidative enzymes XO and MPO was higher in the plasma of patients with HT (XO=9.0±1.2 U/L; MPO=77.3±8.4 U/L) and with HT and DM (XO=11.9±0.9 U/L; MPO=89.5±5.0 U/L) compared to patients with age-related cataract (XO=6.2±0.9 U/L; MPO=52.4±6.3 U/L; P<0.01). Our research has shown that patients with age-related cataract and hypertension were exposed to increased oxidative damage of biomolecules, based on the increased plasma LLF and MDA content and decreased levels of thiol groups. Oxidative changes of biomolecules in these patients were associated with increased activity of the XO, MPO, and GPx enzymes and a lower extracellular SOD activity and total ferric reductive ability of plasma.
Highlights
Oxidative modifications of various biomolecules constantly occur in tissues throughout an individual’s life, but in patients with age-related cataract (ARC), oxidative modifications of proteins and lipids are obvious and a dominant metabolic feature and pathological substrate of disease [1]
Redox state is primarily regulated by a dynamic balance between endogenously synthesized nitric oxide (NO) and superoxide anion radical (O2 À ), which is the main reactive oxygen species (ROS) within vasculature
Given that hypertension is a significant risk factor of ARC development, and that we previously demonstrated involvement of xanthine oxidase (XO) in oxidative damage and earlier development of ARC among diabetic subjects [9], our current study aimed to investigate the relationship between XO and hypertension in patients with ARC
Summary
Oxidative modifications of various biomolecules constantly occur in tissues throughout an individual’s life, but in patients with age-related cataract (ARC), oxidative modifications of proteins and lipids are obvious and a dominant metabolic feature and pathological substrate of disease [1]. The development of ARC involves multiple though inter-related risk factors, including ageing process, exposure to environmental and intrinsic oxidants, diet and lifestyle factors, as well as several systemic disorders, such as diabetes mellitus (DM) and hypertension (HT) [2,3]. Increased presence of oxidants resulting in oxidative stress probably contributes to endothelial dysfunction and the development of hypertension [4]. Redox state is primarily regulated by a dynamic balance between endogenously synthesized nitric oxide (NO) and superoxide anion radical (O2 À ), which is the main ROS within vasculature. NO is a potent vasodilator substance and its diminished availability upon reaction with O2 À causes increased resistance of arterioles, eventually leading to the development of hypertension [5]
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