Paraoxonase-1 (PON1) activity, but not PON1Q192R phenotype, is a predictor of coronary artery disease in a middle-aged Serbian population

Antioxidant status in hypertensive disorders of pregnancy

Objective: Pregnancy can be associated with maternal hypertension leading to possible complications in pregnancy outcome. Antioxidant status may be proned to changes during pregnancy with hypertension. The aim of our study was to estimate antioxidant status through high-risk pregnancies.Methods: Seventy-nine pregnant women with high-risk for preeclampsia development were included and 46 of them developed some hypertensive disorder in pregnancy. Superoxide-dismutase (SOD) and paraoxonase 1 (PON1) activities and relative proportion of PON1 activiity on different HDL subclasses were determined in 1^st, 2^nd, and 3^rd trimester and prior to delivery.Results: SOD activity was significantly lower in 2^nd and 3^rd trimesters when compared to 1^st trimester (P˂0.001) whereas PON1 activity was significantly higher in 3^rd than in 1^st trimester (P˂0.05) in group of hypertensive women. This group had significantly higher SOD and PON1 activities and relative proportion of PON1 on HDL_3c subclasses in the 1^st trimester, significantly increased PON1 in the 3^rd trimester and prior to delivery and significantly higher PON1 activity on HDL_3c subclasses (P˂0.05) than nonhypertensive group. In 1^st trimester and prior to delivery, total PON1 activity and relative proportion of PON1 on HDL_3c subclasses exhibited significant ability to mark out hypertension in pregnancy (P˂0.05).Conclusions: SOD activity decreased whereas total PON1 activity increased during pregnancy with hypertension. Pregnant women with hypertension had higher activities of PON1 and SOD and relative proportion of PON1 on HDL_3c subclasses than nonhypertensive ones. PON1 activity and relative proportion of PON1 on HDL_3c subclasses exhibited significant association with hypertension in pregnancy.

Dietary Strategies to Improve Cardiovascular Health: Focus on Increasing High-Density Lipoprotein Functionality

Cardiovascular disease is one of the leading causes of morbidity and mortality worldwide, with increasing incidence. A cornerstone of cardiovascular disease prevention is lifestyle modification through dietary changes to influence various risk factors such as obesity, hypertension and diabetes. The effects of diet on cardiovascular health are complex. Some dietary components and metabolites directly affect the composition and structure of high-density lipoproteins (HDL) and increase anti-inflammatory and vasoprotective properties. HDLs are composed of distinct subpopulations of particles of varying size and composition that have several dynamic and context-dependent functions. The identification of potential dietary components that improve HDL functionality is currently an important research goal. One of the best-studied diets for cardiovascular health is the Mediterranean diet, consisting of fish, olive oil, fruits, vegetables, whole grains, legumes/nuts, and moderate consumption of alcohol, most commonly red wine. The Mediterranean diet, especially when supplemented with extra virgin olive oil rich in phenolic compounds, has been shown to markedly improve metrics of HDL functionality and reduce the burden, or even prevent the development of cardiovascular disease. Particularly, the phenolic compounds of extra virgin olive oil seem to exert the significant positive effects on HDL function. Moreover, supplementation of anthocyanins as well as antioxidants such as lycopene or the omega-3 fatty acid eicosapentaenoic acid improve parameters of HDL function. In this review, we aim to highlight recent discoveries on beneficial dietary patterns as well as nutritional components and their effects on cardiovascular health, focusing on HDL function.

Association between PON1 rs662 gene polymorphism and serum paraoxonase1 level in coronary artery disease patients in Northern India

Background

Coronary artery disease (CAD) is a leading cause of morbidity and mortality, with a shifting trend towards the younger population. Paraoxonase1 (PON1) is a glycoprotein enzyme associated with high-density lipoprotein (HDL) particles in the blood. It has the ability to protect against lipid oxidation, thereby reducing the risk of atherogenesis. PON1 rs662 gene polymorphism may affect serum PON1 levels as well as its activity and may have a significant role in the pathogenesis of CAD. The present study was conducted to identify the association of PON1 rs662 gene polymorphism with serum PON1 levels in CAD patients in the North Indian population. This case–control study included 71 angiography-proven CAD patients (with > 50% luminal stenosis in one or more coronary arteries) and 71 controls (with < 50% luminal obstruction in angiography). PON1 rs662 gene polymorphism was studied using PCR and RFLP under the standardized protocol. Serum PON1 levels were estimated by ELISA.

Results

The serum PON1 level was significantly lower in the CAD group than in the controls (7.79 ± 3.16 vs. 10.79 ± 3.19 ng/mL; p < 0.0001). Logistic regression analysis showed that homozygous GG genotype of PON1 rs662 SNP has ninefold increased risk of developing CAD in an Indian population (OR = 9.0, 95%CI 2.79–29.06, p = 0.0002). A significantly higher frequency of G allele was also observed in CAD patients than in controls (OR 2.64, 95%CI 1.61–4.33, p = 0.001).

Conclusions

The reduced serum PON1 level is associated with CAD. PON1 rs662 gene polymorphism is significantly associated with CAD susceptibility in the North Indian population.

HDL Proteome and Alzheimer's Disease: Evidence of a Link

Several lines of epidemiological evidence link increased levels of high-density lipoprotein-cholesterol (HDL-C) with lower risk of Alzheimer's disease (AD). This observed relationship might reflect the beneficial effects of HDL on the cardiovascular system, likely due to the implication of vascular dysregulation in AD development. The atheroprotective properties of this lipoprotein are mostly due to its proteome. In particular, apolipoprotein (Apo) A-I, E, and J and the antioxidant accessory protein paraoxonase 1 (PON1), are the main determinants of the biological function of HDL. Intriguingly, these HDL constituent proteins are also present in the brain, either from in situ expression, or derived from the periphery. Growing preclinical evidence suggests that these HDL proteins may prevent the aberrant changes in the brain that characterize AD pathogenesis. In the present review, we summarize and critically examine the current state of knowledge on the role of these atheroprotective HDL-associated proteins in AD pathogenesis and physiopathology.

Lipid profile and lipid oxidative modification parameters in the first trimester of high- risk pregnancies - possibilities for preeclampsia prediction

OBJECTIVES

The goal of this study was to investigate metabolic changes in lipids and oxidative stress parameters in the first trimester of pregnancy with the more specific aim of estimating the significance and strength of researched parameters in the prediction of preeclampsia.

DESIGN AND METHODS

The study included 87 high-risk pregnant (HRG) female subjects, 14 with developed preeclampsia (PEC) and 43 healthy pregnant female subjects matched for gestational age (CG). Thiobarbituric acid-reactive substances (TBARS) concentration, lipid hydroperoxides (LOOH), pro-oxidant antioxidant balance (PAB) and total oxidative status (TOS) were measured as oxidative stress markers, while total antioxidant capacity (TAC) was measured as an antioxidative defense parameter. The Atherogenic Index of Plasma (AIP) was calculated as the base 10 logarithm of the ratio of the plasma concentration of triglycerides (TG) to the plasma concentration of high-density lipoprotein cholesterol (HDL-C), with each concentration expressed in mmol/L.

RESULTS

The results have shown that lipid indices, especially AIP, were significantly higher in the first trimester of HRG (p < 0.001) and PEC (p < 0.001). Oxidative stress parameters were significantlly higher, while TAC was significantly lower in HRG vs. CG [0.7 ± 0.15 vs 1.1 ± 0.16; (p < 0.001)] and in PEC [0.6 ± 0.12 vs 1.1 ± 0.16; (p < 0.001)] vs. CG. Also, in the HRG, results have shown an independent association of AIP with the preeclampsia development (p < 0.05), while placental growth factor did not show the expected level of significance (p = 0.648). Analysis of the Receiver Operating Characteristics (ROC) curves indicated that certain parameters included in the research model have very good diagnostic accuracy for preeclampsia (AUC = 0.856).

CONCLUSIONS

AIP is associated with high-risk pregnancies. Furthermore, our results firmly underscored AIP as a potential marker for preeclampsia prediction.

Paraoxonase 1 and atherosclerosis-related diseases

A direct and an indirect relationship between paraoxonase 1 (PON1) and atherosclerosis exists. Given PON1's physical location within high-density lipoprotein (HDL) particles and its recognized enzyme activity, it is certainly reasonable to suggest that PON1 facilitates the antiatherogenic nature of HDL particles. PON1 also plays a role in regulating reverse cholesterol transport, antioxidative, anti-inflammatory, antiapoptotic, vasodilative, and antithrombotic activities and several endothelial cell functions. HDL dysfunctionality is a more recent issue and seems to be centered on pathological conditions affecting HDL structure and size profiles. This review is focused on the role of PON1 status in different atherosclerosis-related diseases that we have studied over the last twenty years (coronary heart disease, acute ischemic stroke, diabetes mellitus type 2, end-stage renal disease, chronic obstructive pulmonary disease, and sarcoidosis) with the aim to determine the true value of PON1 as a biomarker. The role of PON1 in cancer is also covered, as risk factors and mechanisms underlying both atherosclerosis and cancer share common features.

Evaluation of Association Between Q192R and L55M Genetic Polymorphisms of PON1 and Serum Paraoxonase-1 Activity in Healthy Individuals, a Meta-Analysis

Background and Aims: Several studies have reported the alteration of the paraoxonase 1 (PON1) enzyme activity in various diseases, including diabetes mellitus. The Q192R and L55M are two genetic variations in the coding region of PON1. To evaluate the relationship between these polymorphisms and the alteration in serum paraoxonase activity, the present meta-analysis was carried out. Material and Methods: Eligible studies published before October 2017 was identified in several databases. The paraoxonase activity in subjects with variant alleles of the study polymorphisms were normalized using the activity of the QQ or LL genotypes. The pooled mean effect of alterations in activity level and its 95% confidence intervals (95% CI) was calculated. Results: Thirty-two studies including 11532 healthy participants were used for the present meta-analysis. The paraoxonase activity was increased in the QR and RR genotypes. This elevation was greater among Caucasians than those among Asians and Africans. The activity in the LM and MM genotypes compared with the LL genotype were decreased, this reduction in Caucasians was greater than Africans. Conclusions: At least in part other PON1 polymorphisms and environmental factors may accounts for heterogeneity between studies.

Association of serum amyloid A and oxidative stress with paraoxonase 1 in sarcoidosis patients

BACKGROUND

It has been reported that high-density lipoprotein (HDL) particles have anti-inflammatory and antioxidant roles thanks to different enzymes such as paraoxonase 1 (PON1). Under inflammatory and oxidative stress conditions, HDL particles may lose their protective properties. Sarcoidosis is an inflammatory disease characterized by excessive oxidative stress. Serum amyloid A (SAA) is produced in liver and in granulomas, and its concentration increases in inflammatory conditions contributing to increased catabolism of HDL particles. The aim of our study was to determine PON1 activity, SAA concentration and their associations in patients with sarcoidosis.

MATERIALS AND METHODS

Inflammatory [high-sensitive C-reactive protein (hsCRP), angiotensin-converting enzyme (ACE), SAA], lipid [total cholesterol (TC), HDL-cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), triglycerides (TG)] oxidative stress status parameters [total oxidant status (TOS), malondialdehyde (MDA), pro-oxidant-antioxidant balance (PAB), sulfhydryl (SH) groups] and PON1 activities were determined in serum of 72 patients with sarcoidosis and 62 healthy subjects.

RESULTS

HsCRP (P < 0·05), TC, LDL-c, TG, SAA, TOS, MDA and PAB (P < 0·001) were significantly higher, whereas HDL-c, SH groups and PON1 activity (P < 0·001) were significantly lower in patients with sarcoidosis when compared with controls. PON1 showed significant association with SAA, MDA and PAB. It was shown that 71% of decrease in PON1 activity may be explained by increase in TOS, PAB and SAA concentration.

CONCLUSIONS

We found decreased PON1 activity and increased SAA concentration in patients with sarcoidosis. Inflammatory condition presented by high SAA was implicated in impaired HDL functionality evident through dysregulated PON1 activity. Excessive oxidative stress was also involved in dysregulation of PON1 activity.

Association between PON1 rs662 polymorphism and coronary artery disease

BACKGROUND/OBJECTIVES

Paraoxonase 1 (PON1) is a plasma enzyme that is capable of inhibiting the progression of atherosclerosis, and is associated with susceptibility of coronary artery disease (CAD). PON protein expression is present in human aortic tissue and it plays an important role in the progression of atherosclerosis. This study aimed to investigate PON1 immunohistochemistry in human coronary arteries, determine its polymorphisms and plasma status, and analyze its association with the risk of CAD.

SUBJECTS/METHODS

PON1 expression in human coronary artery tissues was detected by immunohistochemical staining. PON1 polymorphisms were determined by polymerase chain reaction direct sequencing in 2456 unrelated Chinese Han individuals. Serum PON1 levels were indirectly reflected by PON1 activity towards paraoxon and phenylacetate by spectrophotometry, and by its concentrations using a human enzyme-linked immunosorbent assay.

RESULTS

Immunohistochemical analysis showed that PON1 expression was lower in atherosclerotic arteries than in normal arteries. PON1 Q192R (rs662) had a significant effect on the risk of CAD (P=0.001). In a logistic regression model, after adjusting for conventional risk factors of CAD, 192R allele carriers had a significantly higher risk of CAD than other allele carriers. Serum PON1 activity and concentrations were significantly reduced in CAD patients compared with controls (P<0.05), and highly associated with the R allele.

CONCLUSIONS

Low PON1 expression in human atherosclerotic coronary arteries is associated with CAD. Moreover, PON1 Q192R polymorphism is significantly associated with susceptibility of CAD in the Chinese Han population, and the 192R allele might be an independent predictor for CAD.

Methylmercury-induced inhibition of paraoxonase-1 (PON1)-implications for cardiovascular risk

Methylmercury (MeHg) has been associated with increased risk for cardiovascular disease in some but not all epidemiology studies. These inconsistent results may stem from the fact that exposure typically occurs in the context of fish consumption, which is also associated with cardioprotective factors such as omega-3 fatty acids. Mechanistic information may help to understand whether MeHg represents a risk to cardiovascular health. MeHg is a pro-oxidant that inactivates protein sulfhydryls. These biochemical effects may diminish critical antioxidant defense mechanism(s) involved in protecting against atherosclerosis. One such defense mechanism is paraoxonase-1 (PON1), an enzyme present on high-density lipoproteins and that prevents the oxidation of blood lipids and their deposition in vascular endothelium. PON1 is potentially useful as a clinical biomarker of cardiovascular risk, as well as a critical enzyme in the detoxification of certain organophosphate oxons. MeHg and other metals are known to inhibit PON1 activity in vitro. MeHg is associated with lowered serum PON1 activity in a fish-eating population. The implications of lowering PON1 are evaluated by predicting the shift in PON1 population distribution induced by various doses of MeHg. An MeHg dose of 0.3 μg/kg/d is estimated to decrease the population average PON1 level by 6.1% and to increase population risk of acute cardiovascular events by 9.7%. This evaluation provides a plausible mechanism for MeHg-induced cardiovascular risk and suggests means to quantify the risk. This case study exemplifies the use of upstream disease biomarkers to evaluate the additive effect of chemical toxicity with background disease processes in assessing human risk.

Increased Levels of Human Carotid Lesion Linoleic Acid Hydroperoxide in Symptomatic and Asymptomatic Patients Is Inversely Correlated with Serum HDL and Paraoxonase 1 Activity

Human carotid plaque components interact directly with circulating blood elements and thus they might affect each other. We determined plaque paraoxonase1 (PON1) hydrolytic-catalytic activity and compared plaque and blood levels of lipids, HDL, PON1, and HbA1c, as well as plaque-oxidized lipids in symptomatic and asymptomatic patients. Human carotid plaques were obtained from symptomatic and asymptomatic patients undergoing routine endarterectomy, and the lesions were ground and extracted for PON activity and lipid content determinations. Plaque PONs preserved paraoxonase, arylesterase, and lactonase activities. The PON1-specific inhibitor 2-hydroxyquinoline almost completely inhibited paraoxonase and lactonase activities, while only moderately inhibiting arylesterase activity. Oxysterol and triglyceride levels in plaques from symptomatic and asymptomatic patients did not differ significantly, but plaques from symptomatic patients had significantly higher (135%) linoleic acid hydroperoxide (LA-13OOH) levels. Their serum PON1 activity, cholesterol and triglyceride levels did not differ significantly, but symptomatic patients had significantly lower (28%) serum HDL levels and higher (18%) HbA1c levels. Thus LA-13OOH, a major atherogenic plaque element, showed significant negative correlations with serum PON1 activity and HDL levels, and a positive correlation with the prodiabetic atherogenic HbA1c. Plaque PON1 retains its activity and may decrease plaque atherogenicity by reducing specific oxidized lipids (e.g., LA-13OOH). The inverse correlation between plaque LA-13OOH level and serum HDL level and PON1 activity suggests a role for serum HDL and PON1 in LA-13OOH accumulation.

Quantitative assessment of the influence of paraoxonase 1 activity and coronary heart disease risk

Human paraoxonase 1 (PON1) is a calcium-dependent high-density lipoprotein associated ester hydrolase that has attracted considerable attention as a candidate factor for coronary heart disease (CHD) based on its function as a key factor in lipoprotein catabolism pathways. This meta-analysis aimed to clarify the inconsistency of published studies and to establish a comprehensive picture of the relationship between PON1 activity and CHD susceptibility. A systematic search was performed from PubMed, Web of Science, EMBASE, and CNKI databases. Ratio of means (RoM) between case and control and 95% confidence intervals (CIs) were calculated using a random-effects model. The source of heterogeneity was explored by subgroup analysis and meta-regression. We identified 47 eligible studies including a total of 9853 CHD cases and 11,408 controls. The pooled analysis showed that CHD patients had a 19% lower PON1 activity than did the controls (RoM=0.81; 95% CI: 0.74-0.89, p<10(-5)). In the subgroup analyses by CHD end points, a similar effect size was observed with coronary stenosis and myocardial infarction subgroups, with corresponding RoM of 0.81 (95% CI: 0.73-0.89, p<10(-4)) and 0.83 (95% CI: 0.74-0.93, p=0.001), respectively. Decreased PON1 activity associated with CHD risk was observed in almost all subgroup analysis according to ethnicity, sample size, study design, mean age of cases, source, and type of control. Decreased PON1 activity may act as a risk factor for the development of CHD. Progressive decrease in serum PON1 activity may exist for an individual with severe disease. However, larger studies using a prospective approach are needed to confirm our results.

Association between PON1 activity and coronary heart disease risk: a meta-analysis based on 43 studies

Paraoxonase 1 (PON1) is reported to have antioxidant and cardioprotective properties. The relationship between PON1 activity and coronary heart disease (CHD) risk in humans has been reported among various ethnic populations in the past decade. However, these studies have yielded contradictory results. To investigate this inconsistency, we conducted a meta-analysis of 43 studies involving a total of 20,629 subjects to evaluate the effect of PON1 activity on susceptibility for CHD. We also systematically explored potential sources of heterogeneity using subgroup analysis and meta-regression. Significant decreases paraoxonase activity of PON1 were observed in CHD patients compared with non-CHD controls with SMD of -0.78 (95% CI: -0.98, -0.57; P<0.001). Similar results were also found for arylesterase activity of PON1 with SMD of -0.50 (95% CI: -0.64, -0.36; P<0.001). In the subgroup analysis by ethnicity, CHD phenotype, sample size, source of controls, mean age and BMI of cases, significantly increased risks were also found. In addition, our analyses detected a possibility of publication bias with an overestimate of the true association by smaller studies. This meta-analysis demonstrated that decreasing in PON1 activity is a risk factor associated with increased CHD susceptibility. However, additional very large-scale studies are warranted to provide conclusive evidence on the effects of PON1 activity on risk of CHD.

Four genetic polymorphisms of paraoxonase gene and risk of coronary heart disease: a meta-analysis based on 88 case-control studies

OBJECTIVE

The human paraoxonase (PON) is calcium dependent HDL associated ester hydrolase which has attracted considerable attention as a candidate gene for coronary heart disease based on its enzyme function as a key factor in lipoprotein catabolism pathways. Many studies have examined the association between polymorphisms in the PON gene and risk of coronary heart disease (CHD), but the results have been inconsistent.

METHODS

We conducted a meta-analysis of 88 studies on 4 PON polymorphisms [Q192R, L55M, and T(-107)C in the PON1 and the S311C in the PON2] published before August 2010, including a total of 24,702 CHD cases and 38,232 controls. We also systematically explored potential sources of heterogeneity.

RESULT

In a combined analysis, the summary per-allele odds ratio for CHD of the 192R was 1.11 (95% CI: 1.05-1.17). However, when the analyses were restricted to 10 larger studies (n>500 cases), the summary per-allele odds ratio was 0.96 (95% CI: 0.90-1.02). Our analyses detected a possibility of publication bias with an overestimate of the true association by smaller studies. A meta-analysis of studies on the 55M, (-107)T, and 311C variant showed no significant overall association with CHD, yielding a per-allele odds ratio of 0.94 (95% CI: 0.88-1.00), 1.02 (95% CI: 0.91-1.15) and 1.02 (95% CI: 0.90-1.16) respectively.

CONCLUSIONS

This meta-analysis suggested an overall weak association between the R192 polymorphism and CHD risk.

Paraoxonase activity in athletes with depleted iron stores and iron-deficient erythropoiesis

OBJECTIVE

The aim of this study was to evaluate how conditions that precede anaemia (iron store depletion and iron-deficient erythropoiesis) affect human serum paraoxonase PON1 activity.

DESIGN AND METHODS

Based on haemoglobin, transferrin saturation and serum ferritin values 119 athletes were divided into three groups: with iron depletion, with deficient erythropoiesis and controls. The following parameters were measured: paraoxonase activity towards paraoxon (POase) and diazoxon (DZOase), lipid hydroperoxides (LOOH), the pro-oxidant-antioxidant balance (PAB), red blood cells (RBC) and lipid status.

RESULTS

Significant differences were found between athletes with different stages of iron deficiency and controls with respect to PON 1 activity and oxidative stress status parameters (Wilks' Lambda=0.712, F=5.241, p<0.001, η(2)=0.156). There was no significant difference between the PON1 192 Q and R polymorphism distribution in the two groups of athletes with different stages of iron deficiency and controls (χ(2)=1.086; p=0.896). PON1 activity was positively correlated with RBCs, haemoglobin, transferrin saturation (p<0.001) and ferritin (p=0.037) and negatively correlated with LOOH (p=0.044) in all three study groups.

CONCLUSIONS

Deficient erythropoiesis in athletes contributes to impaired PON1 activity. In contrast, iron depletion, regardless of increased oxidative stress, does not affect PON1 activity.

Association of paraoxonase activity and coronary collateral flow

OBJECTIVES

Paraoxonase is a high-density lipoprotein-bound antioxidant enzyme that inhibits atherosclerosis and endothelial dysfunction. Coronary collateral flow is a crucial clinical entity with significant impact on the cardiovascular morbidity and mortality. This study sought to determine the relationship between the degree of angiographically visible coronary collateral circulation and serum paraoxonase activity.

METHODS

The study population included 98 patients (mean age=57.9+/-10.1 years, 65 men) with angiographically documented total occlusion in one of the major coronary arteries. Development of collaterals was classified by Rentrop's method. Patients were defined as having poorly developed collaterals for Rentrop grades 0 and 1 or well-developed collaterals for Rentrop grades 2 and 3. Serum paraoxonase and arylesterase activities were measured spectrophotometrically.

RESULTS

Statistically significant differences between well and poorly developed collateral groups in respect to serum low-density lipoprotein cholesterol level (P=0.046), and serum paraoxonase (P=0.001), and arylesterase (P=0.014) activities were present. Serum low-density lipoprotein cholesterol level (chi=4.15, beta=-0.347, P=0.032) and serum paraoxonase activity (chi=10.43, beta=0.008, P=0.022) were independent predictors of well-developed coronary collateral flow. Serum paraoxonase activity gradually increased from collateral grade 0 to collateral grade 3 (analysis of variance P=0.003). Serum paraoxonase (r=0.362 and P<0.001) and arylesterase (r=0.245 and P=0.015) activities were both correlated with collateral flow grade.

CONCLUSION

Findings of this study suggest that serum paraoxonase activity is independently associated with the degree of coronary collateral flow and reduced serum paraoxonase activity might represent a biochemical marker of impaired coronary collateral flow.

Association of oxidative stress and PON1 with LDL and HDL particle size in middle-aged subjects

BACKGROUND

Alterations in plasma lipoprotein subclass distributions affect atherosclerosis risk. Smaller, denser low-density lipoprotein (LDL) particles (sdLDL) are more susceptible to oxidation. In contrast, most of the protective effects of high-density lipoproteins (HDL) are attributable to larger particles. This study investigates the connection between LDL and HDL particle heterogeneity and oxidative stress, antioxidative defence (AOD) and paraoxonase (PON1) status in a healthy middle-aged Serbian population.

MATERIALS AND METHODS

LDL and HDL particle sizes and subclass distributions were measured by gradient gel electrophoresis in 104 men and 103 women, aged 53 +/- 9.4 years. PON1 activities and PON1(Q192R) phenotypes were determined with paraoxon and diazoxon as substrates. The oxidative stress/AOD status was estimated by measuring malondialdehyde (MDA) and superoxide-anion (O2*(-)) levels and superoxide-dismutase (SOD) activity.

RESULTS

Subjects with sdLDL had significantly higher MDA (P < 0.001) and O2*(-)(P < 0.05) levels and greater diazoxonase (DZOase) activity (P < 0.05) compared to subjects with larger LDL particles. A high MDA concentration was a significant predictor of the sdLDL phenotype (P < 0.005). Increased levels of and MDA were associated with smaller HDL(3) subclass abundance. Reduced HDL particle size was associated with lower DZOase activity (P < 0.01).

CONCLUSIONS

Even in the absence of symptoms of atherosclerosis, sdLDL particles are associated with increased oxidative stress, which may stimulate a compensatory rise in PON1 DZOase activity. Elevated oxidative stress may significantly affect HDL subclass distribution, resulting in the accumulation of smaller, denser HDL particles with diminished antioxidative capacity.