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Objectives We aimed to evaluate the association of lipid peroxidation, protein oxidation and antioxidant system, and to assess an association with the severity of the disease, in patients with and without coronary artery disease (CAD) documented by coronary angiography. Design and methods The population included 208 patients, undergoing clinically indicated coronary angiography. While the subjects with normal coronary angiograms ( n = 54) were evaluated as controls, the patients with CAD ( n = 154) were divided into three categories according to the number of diseased coronaries; one-vessel ( n = 50), two-vessels ( n = 51) and three-vessels ( n = 53). Lipid parameters were determined by routine laboratory methods. Plasma malondialdehyde and vitamin E concentrations were determined with the high-performance liquid chromatography. Other oxidant and antioxidant parameters were studied spectrophotometrically. Results While plasma malondialdehyde levels, the susceptibilities of erythrocyte and apolipoprotein B containing lipoproteins to in vitro induced oxidative stress, serum protein carbonyls, low density lipoprotein-cholesterol, triglyceride, apolipoprotein B and lipoprotein (a) levels had significantly increased, high-density lipoprotein–cholesterol and apolipoprotein AI levels, erythrocyte glutathione peroxidase, glutathione reductase, glucose 6 phosphate dehydrogenase, serum catalase, paraoxonase and arylesterase activities, plasma vitamin E and C and carotenoid levels had significantly decreased. The odds ratios for one-, two-, and three-vessel disease increased across especially higher tertiles of concentrations for oxidation parameters and lower tertiles of concentrations for antioxidant parameters. Conclusions According to the results, we suggest that increased lipid and protein oxidation products and decreased antioxidant enzymes and vitamins contribute to increased oxidative stress which in turn is related to the severity of the disease.

Objectives: To assess the relationship between lipoprotein (a) [Lp (a)] and lipoprotein oxidation in patients with coronary artery disease (CAD). Design and methods: Oxidation of apolipoprotein (apo)B-containing lipoproteins, vitamin E, carotenoids, lipid-lipoprotein levels were determined in 171 CAD and 70 non-CAD subjects. Results: In CAD patients with Lp (a) concentrations greater than or equal to 30 mg/dL; total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), malondialdehyde (MDA), and apo B levels were significantly higher and lag-time and age were significantly lower than those of CAD patients with Lp (a) concentrations < 30 mg/dL. In non-CAD subjects with Lp (a) concentrations a 30 mg/dL; TC, LDL-C, and vitamin E levels were significantly higher and lag-time was significantly lower than those of non-CAD subjects with Lp (a) concentrations < 30 mg/dL. In CAD patients, Lp (a) correlated negatively with lag-time and positively with MDA levels. Lp (a) correlated negatively with lag-time and vitamin E levels in non-CAD subjects. Conclusions: We have shown that plasma apo B-containing lipoproteins of both CAD and non-CAD subjects with Lp (a) levels 30 mg/dL are more susceptible to in vitro oxidative modification than those of subjects with Lp (a) levels < 30 mg/dL. The relationship between Lp (a) and enhanced susceptibility of apo B-containing lipoproteins to oxidation, appears to support routine investigation of Lp (a).