Levels of thiobarbituric acid-reactive substance in plasma from coronary artery disease patients

Oxidative Stress Biomarkers in Coronary Artery Disease

Oxidative stress plays a central role in atherogenesis, implicated in endothelial dysfunction, coronary plaque formation, and destabilization. Therefore, identifying oxidative stress in the vascular wall by reliable biomarkers could aid in early diagnosis and better coronary artery disease (CAD) prognostication. Because of the short half-life of reactive oxygen species, the current approach is to measure stable products generated by the oxidation of macromolecules in plasma or urine. Most popular oxidative stress biomarkers are oxidized low-density lipoprotein, myeloperoxidase and lipid peroxidation biomarkers, such as malondialdehyde and F2-isoprostanes. Oxidative protein modification biomarkers and oxidized phospholipids have also been studied and discussed in the present review. Most of these biomarkers are associated with the presence and extent of CAD, are elevated in patients with acute coronary syndromes, and may predict outcomes independent of traditional CAD risk factors. However, further standardization of measurement methods and assessment in large randomized clinical trials are required to integrate these biomarkers into clinical practice. In addition, evidence that these biomarkers detect oxidative stress in the vascular wall lacks and more specific biomarkers should be developed to identify vascular oxidative stress. Consequently, several oxidative stress biomarkers have been developed, most of which can be associated with the presence and extent of CAD and event prognosis. However, they still have significant limitations that hinder their integration into clinical practice.

Lipidomics of Bioactive Lipids in Acute Coronary Syndromes

Acute coronary syndrome (ACS) refers to ischemic conditions that occur as a result of atherosclerotic plaque rupture and thrombus formation. It has been shown that lipid peroxidation may cause plaque instability by inducing inflammation, apoptosis, and neovascularization. There is some evidence showing that these oxidized lipids may have a prognostic value in ACS. For instance, higher levels of oxidized phospholipids on apo B-100 lipoproteins (OxPL/apoB) predicted cardiovascular events independent of traditional risk factors, C-reactive protein (hsCRP), and the Framingham Risk Score (FRS). A recent cross-sectional study showed that levels of oxylipins, namely 8,9-DiHETrE and 16-HETE, were significantly associated with cardiovascular and cerebrovascular events, respectively. They found that with every 1 nmol/L increase in the concentrations of 8,9-DiHETrE, the odds of ACS increased by 454-fold. As lipid peroxidation makes heterogonous pools of secondary products, therefore, rapid multi-analyte quantification methods are needed for their assessment. Conventional lipid assessment methods such as chemical reagents or immunoassays lack specificity and sensitivity. Lipidomics may provide another layer of a detailed molecular level to lipid assessment, which may eventually lead to exploring novel biomarkers and/or new treatment options. Here, we will briefly review the lipidomics of bioactive lipids in ACS.

Increased membrane lipid peroxidation and decreased Na+/K+-ATPase activity in erythrocytes of patients with stable coronary artery disease

OBJECTIVES

We aimed to determine erythrocyte membrane lipid peroxidation levels and Na/K-ATPase activity in patients with and without coronary artery disease (CAD) documented by coronary angiography.

DESIGN AND METHODS

A total of 144 patients who had undergone coronary angiography were divided into a CAD group (n=82) and a non-CAD group (control group, n=62) according to the results of coronary angiography. Lipid peroxide levels in plasma and the erythrocyte membrane were measured using a fluorimetric method. Total antioxidant status and Na/K-ATPase activity in plasma were determined using spectrophotometric methods.

RESULTS

Lipid peroxidation levels were significantly higher in the erythrocyte membrane of CAD patients compared with controls, whereas Na/K-ATPase activity was significantly lower in the erythrocyte membrane of CAD patients compared with controls. The coronary artery scores were correlated positively with membrane lipid peroxidation (r=0.324, P<0.001) and negatively with Na/K-ATPase activity (r=-0.302, P<0.001).

CONCLUSION

This study shows that the levels of membrane lipid peroxidation and Na/K-ATPase activity are correlated with the severity of CAD.

Derivatives of reactive oxygen metabolites correlates with high-sensitivity C-reactive protein

AIM

High-sensitivity C-reactive protein (hsCRP) is a predictor of cardiovascular events. Although oxidative stress may also be related to cardiovascular disease, there are few studies comparing the two. We therefore examined the association of hsCRP, serum lipids, and derivatives of reactive oxygen metabolites (D-ROMs) in coronary artery disease.

METHODS

We measured the levels of serum lipids, hsCRP, plasma brain natriuretic peptides (BNP) and D-ROMs in 131 consecutive patients undergoing cardiac catheterization. We divided these subjects into three groups according to their levels of hsCRP.

RESULTS

In group C (hsCRP>3.0 mg/L), mean levels of serum D-ROMs were significantly higher than in groups A (hsCRP<1.0 mg/L) and B (hsCRP 1.0 to 3.0 mg/L). Serum levels of D-ROMs and log (hsCRP) correlated in the total population (r=0.479, p<0.0001), and D-ROMs, HDL-C, LDL-C and log-transformed plasma BNP were independent predictors of hsCRP (p<0.0001).

CONCLUSION

We concluded that oxidative stress increases in patients at high risk for cardiovascular events based on their hsCRP.

The effect of strawberries in a cholesterol-lowering dietary portfolio

Effective diets reduce blood lipids and oxidative damage, both of which have been linked to the complications of diabetes and coronary heart disease. Our objective was to assess the effect of adding strawberries, as a source of antioxidants, to improve the antioxidant effect of a cholesterol-lowering diet (dietary portfolio). To this end, 28 hyperlipidemic subjects who had followed the dietary portfolio consisting of soy, viscous fiber, plant sterol, and nuts for a mean of 2.5 years were randomized to receive supplements of strawberries (454 g/d, 112 kcal) or additional oat bran bread (65 g/d, 112 kcal, approximately 2 g beta-glucan) (control) in a randomized 1-month crossover study with a 2-week washout. Strawberry supplementation resulted in a greater reduction in oxidative damage to low-density lipoprotein (LDL) measured as thiobarbituric acid-reactive substances in the LDL fraction (P = .014). At the end of the strawberry period, reductions in LDL cholesterol and in the ratio of total to high-density lipoprotein cholesterol were maintained close to 1-year values at -13.4% +/- 2.1% and -15.2% +/- 1.7%, respectively (P < .001), and were similar to the post-oat bran bread values. Strawberries also improved the palatability of the diet. We conclude that strawberry supplementation reduced oxidative damage to LDL while maintaining reductions in blood lipids and enhancing diet palatability. Added fruit may improve the overall utility of diets designed to lower coronary heart disease risk.

Is elevated serum ceruloplasmin level associated with increased risk of coronary artery disease?

BACKGROUND

An imbalance between the lipid peroxidation process and antioxidative protection is associated with the pathophysiology of coronary artery disease (CAD). The authors aimed to determine the relationship between the contributors of antioxidant protection, such as paraoxonase-1 (PON1) activity, albumin, vitamin C and ceruloplasmin (CP) levels, and lipid peroxidation indicators.

METHODS

In the present study, the activity of PON1 was measured, together with serum concentrations of a variety of lipid constituents, albumin, vitamin C and CP levels, and lipid peroxidation indicators (conjugated dienes [CDs] and thiobarbituric acid-reactive substances [TBARS]). Data were gathered from 26 nondiabetic, angiographically proven, Turkish CAD patients and 26 healthy controls living in the Antalya region (Turkey).

RESULTS

CAD patients had significantly lower PON1 activity, high-density lipoprotein cholesterol, vitamin C and albumin concentrations, and higher CP, CD and TBARS concentrations than the controls. In the entire study population (n=52), serum CP levels were positively correlated with TBARS and CD levels, and negatively correlated with albumin and vitamin C levels, as well as with PON1 activity. On multiple logistic regression analysis, risk factors associated with CAD included high CP and low albumin levels.

CONCLUSIONS

CAD patients and controls were matched for age and sex, and high CP and low albumin levels were found to be independent risk factors for CAD. The present data gathered from the study group living in the Antalya region verifies that in CAD patients, CP impairs the oxidant-antioxidant balance in favour of the oxidants.

Circulating lipid hydroperoxides predict cardiovascular events in patients with stable coronary artery disease: the PREVENT study

OBJECTIVES

This study was designed to determine the predictive value of lipid hydroperoxide (LOOH) levels for adverse cardiovascular outcomes in patients with stable coronary artery disease (CAD).

BACKGROUND

Oxidative modification of circulating lipids contributes to inflammation and endothelial dysfunction, which are hallmark features of atherosclerosis. A serum biomarker of oxidation is LOOH, which is a primary product of fatty acid peroxidation.

METHODS

Serum LOOH levels were measured and correlated with clinical events over a 3-year period in 634 patients with angiographic evidence of CAD.

RESULTS

Baseline LOOH levels in the highest quartile were associated with hazard ratios of 3.24 (95% confidence interval [CI] 1.86 to 5.65; p = 0.0001) for nonfatal vascular events (n = 149), 1.80 (95% CI 1.13 to 2.88; p = 0.014) for major vascular procedures (n = 139), and 2.23 (95% CI 1.44 to 3.44; p = 0.0003) for all vascular events and procedures. Baseline LOOH levels correlated with serum levels of soluble intercellular adhesion molecule-1 (p = 0.001) and thiobarbituric acid reactive substances (p = 0.001) as well as the mean percent change in stenosis for large segments >50% stenosed (p = 0.048). A multivariate proportional hazards model, adjusted for traditional risk factors and inflammatory markers, showed an independent effect of LOOH on nonfatal vascular events, vascular procedures, and all events or procedures. Amlodipine treatment was associated with reduced cardiovascular events and changes in LOOH levels compared with placebo.

CONCLUSIONS

Elevated LOOH levels were predictive of nonfatal vascular events and procedures in patients with stable CAD, independent of traditional risk factors and inflammatory markers.

Influence of lycopene and vitamin C from tomato juice on biomarkers of oxidative stress and inflammation

A human study was carried out to investigate whether tomato juice, rich in natural lycopene and fortified with vitamin C, is able to reduce several biomarkers of oxidative stress and inflammation and whether the effect can be attributed to lycopene, vitamin C or any other micronutrient. Following a 2-week depletion phase, volunteers were assigned randomly to ingest either tomato juice with (LC) or without (L) vitamin C fortification for 2 weeks (daily dose 20·6 mg lycopene and 45·5/435 mg vitamin C). Plasma and urine were analysed for carotenoids and vitamin C, lipid status, antioxidant capacity, thiobarbituric acid reactive substances (TBARS) and 8-epi-PGF2α, protein carbonyls, cytokines IL-1β and TNFα and C-reactive protein (CRP). The consumption of tomato juice led to a reduction in total cholesterol levels (L: 157·6v. 153·2 mg/dl,P = 0·008; LC: 153·4v. 147·4 mg/dl,P = 0·002) and that of CRP (L: 315·6v. 262·3 μg/l,P = 0·017; LC: 319·2v. 247·1 μg/l,P = 0·001) in both groups. The vitamin C-fortified juice slightly raised the antioxidant capacity in urine and decreased TBARS in plasma and urine. All other markers were affected to a lesser extent or remained unchanged. Cholesterol reduction was correlated with lycopene uptake (P = 0·003), whereas the other effects could not be related with particular micronutrients. Any beneficial effects of tomato consumption for human health cannot be attributed only to lycopene and, as the additional supplementation with ascorbic acid indicates, a variety of antioxidants might be needed to optimize protection against chronic diseases.

Elevated hydroperoxide levels as a prognostic predictor of mortality in a cohort of patients with cardiovascular disease

The aim of this study was to evaluate whether hydroperoxide levels, an index of oxidative stress, predict cardiac and total death in patients with cardiovascular disease. Serum hydroperoxide levels were measured in 157 consecutive inpatients, followed during a mean follow-up of 20+/-0.3 months. Elevated oxidative stress resulted in an independent predictors for cardiac death, suggesting that hydroperoxide evaluation could provide an adjunctive estimate in the evaluation of prognosis in the cardiovascular clinical setting.

Serum levels of thiobarbituric acid reactive substances predict cardiovascular events in patients with stable coronary artery disease

OBJECTIVES

The objective of this study was to test the predictive value of an oxidative stress biomarker in 634 patients from the Prospective Randomized Evaluation of the Vascular Effects of Norvasc Trial (PREVENT).

BACKGROUND

Oxidative stress contributes to mechanisms of atherosclerosis and plaque instability. Biomarkers of oxidation, such as malondialdehyde (MDA), may represent independent indicators of risk for patients with stable coronary artery disease (CAD).

METHODS

Serum MDA levels were measured as thiobarbituric acid reactive substances (TBARS) in 634 patients with documented CAD using reverse-phase high-performance liquid chromatography and spectrophotometric approaches.

RESULTS

During the three-year study, there were 51 major vascular events such as fatal/nonfatal myocardial infarction, 149 hospitalizations for nonfatal vascular events, and 139 patients underwent a major vascular procedure. At baseline, patients with TBARS levels in the highest quartile had a relative risk (RR) of 3.30 (95% confidence interval [CI] 1.47 to 7.42; p = 0.038) for major vascular events, RR of 4.10 (95% CI 2.55 to 6.60; p < 0.0001) for nonfatal vascular events, and RR of 3.84 (95% CI 2.56 to 5.76; p < 0.0001) for major vascular procedures. The effect of TBARS on events and procedures was also seen in a multivariate model adjusted for inflammatory markers (C-reactive protein, soluble intercellular adhesion molecule-1, interleukin-6), and other risk factors (age, low-density lipoprotein, high-density lipoprotein, total cholesterol, triglycerides, body mass index, and blood pressure). This analysis showed an independent effect of TBARS on major vascular events (p = 0.0149), nonfatal vascular events (p < 0.0001), major vascular procedures (p < 0.001), and all vascular events and procedures (p < 0.0001).

CONCLUSIONS

Serum levels of TBARS were strongly predictive of cardiovascular events in patients with stable CAD, independently of traditional risk factors and inflammatory markers.

Lycopene from two food sources does not affect antioxidant or cholesterol status of middle-aged adults

Background

Epidemiological studies have reported associations between reduced cardiovascular disease and diets rich in tomato and/or lycopene. Intervention studies have shown that lycopene-containing foods may reduce cholesterol levels and lipid peroxidation, factors implicated in the initiation of cardiovascular disease. The objective of this study was to determine whether consumption of lycopene rich foods conferred cardiovascular protection to middle-aged adults as indicated by plasma lipid concentrations and measures of ex vivo antioxidants.

Methods

Ten healthy men and women consumed a low lycopene diet with no added lycopene (control treatment) or supplemented with watermelon or tomato juice each containing 20 mg lycopene. Subjects consumed each treatment for three weeks in a crossover design. Plasma, collected weekly was analyzed for total cholesterol, high density lipoprotein cholesterol (HDL-C) and triglyceride concentrations and for the antioxidant biomarkers of malondialdehyde formation products (MDA), plasma glutathione peroxidase (GPX) and ferric reducing ability of plasma (FRAP). Data were analyzed using Proc Mixed Procedure and associations between antioxidant and lipid measures were identified by Pearson's product moment correlation analysis.

Results

Compared to the control diet, the lycopene-containing foods did not affect plasma lipid concentrations or antioxidant biomarkers. Women had higher total cholesterol, HDL-C and triglyceride concentrations than did the men. Total cholesterol was positively correlated to MDA and FRAP while HDL-C was positively correlated to MDA and GPX. GPX was negatively correlated to triglyceride concentration.

Conclusions

The inclusion of watermelon or tomato juice containing 20 mg lycopene did not affect plasma lipid concentrations or antioxidant status of healthy subjects. However, plasma cholesterol levels impacted the results of MDA and FRAP antioxidant tests.

Tumour necrosis factor-alpha plasma level in patients with type 1 diabetes mellitus and its association with glycaemic control and cardiovascular risk factors

OBJECTIVES

Diabetic patients reveal a significant increase in their cardiovascular risk. Beside glycaemic control and management of established risk factors, determination of cytokines, like serum levels of tumour necrosis factor-alpha (TNF-alpha), might offer a tool to determine patients at high risk. The cytokine TNF-alpha reveals a complex relationship with diabetes. It is involved in beta-cell damage leading to type 1 diabetes, causes insulin resistance associated with obesity and is of influence in the formation of atherosclerotic vascular lesions. We were interested in the possible association of this cytokine with metabolic control and cardiovascular risk factors in patients with type 1 diabetes.

DESIGN AND SUBJECTS

TNF-alpha plasma levels were determined in 44 outdoor patients (15 women, 29 men) with type 1 diabetes mellitus (mean duration 11.2 +/- 8.7 years) and in 24 healthy controls by use of a solid phase enzyme amplified sensitivity immunoassay (TNF-alpha ELISA, Biosource Fleurus, Belgium). None of our study participants suffered from inflammatory or other concurrent diseases. Relationships between variables were evaluated by non-parametric Spearman correlation coefficients.

RESULTS

TNF-alpha plasma levels were significantly higher in diabetic patients (19.3 +/- 7.5 pg mL-1) than in non-diabetic subjects (11.1 +/- 5.8 pg mL-1; P < 0. 023), and revealed a significant positive correlation with glycated haemoglobin (HbA1c) (r = 0.43; P < 0.004) and fructosamine (r = 0. 31; P < 0.049) values, and a negative correlation with HDL cholesterol (r = -0.36; P < 0.018) and apoAI-levels (r = -0.37; P < 0.015). These relationships could be observed in patients with a duration of diabetes for more than 5 years, as well as in patients with a shorter duration of diabetes. In the male group, TNF-alpha plasma levels revealed a significant positive correlation with plasma levels of thiobarbituric acid reacting substances (r = 0.61; P < 0.001). Plasma levels of thiobarbituric acid reacting substances showed a positive correlation with the duration of diabetes (r = 0. 58; P < 0.008), as well as with the serum levels of the vascular adhesion molecules intercellular adhesion molecule (ICAM) (r = 0.34; P < 0.051) and vascular cell adhesion molecule (VCAM) (r = 0.30; P < 0.052).

CONCLUSIONS

Our data indicate that TNF-alpha plasma levels are increased in type 1 diabetes mellitus and reveal a significant association with metabolic long-term control parameters, HbA1c and fructosamine for glycaemic control, and HDL cholesterol for triglyceride metabolism, as well with lipid peroxidation.

Cardiovascular disease from copper deficiency--a history

Although the nutritional essentiality of copper was established in 1928, a preoccupation with hematology delayed the discovery of cardiovascular disease from copper deficiency for more than a decade. Anatomical studies of several species of deficient animals revealed, interalia, aortic fissures and rupture, arterial foam cells and smooth muscle migration, cardiac enlargement and rupture, coronary artery thrombosis and myocardial infarction. Abnormal biochemistry in deficiency probably contributes to these lesions, e.g., decreased activities of lysyl oxidase and superoxide dismutase which result in failure of collagen and elastin crosslinking and impaired defense against free radicals. Copper deficiency also decreases copper in hearts and other organs and cells and increases cholesterol in plasma. Abnormal physiology from deficiency includes abnormal electrocardiograms, glucose intolerance and hypertension. People with ischemic heart disease have decreased cardiac and leucocyte copper and decreased activities of some copper-dependent enzymes. Copper depletion experiments with men and women have revealed abnormalities of lipid metabolism, blood pressure control, and electrocardiograms plus impaired glucose tolerance. The Western diet often is as low in copper as that proved insufficient for these people. Knowledge of nutritional history can be useful in addressing contemporary nutritional problems.