Effect of antioxidants on oxidative modification of LDL

Impact of dietary n-6/n-3 fatty acid ratio of atherosclerosis risk: A review

Atherosclerosis is a causative factor associated with cardiovascular disease (CVD). Over the past few decades, extensive research has been carried out on the relationship between the n-6/n-3 fatty acid ratio of ingested lipids and the progression of atherosclerosis. However, there are still many uncertainties regarding the precise nature of this relationship, which has led to challenges in providing sound dietary advice to the general public. There is therefore a pressing need to review our current understanding of the relationship between the dietary n-6/n-3 fatty acid ratio and atherosclerosis, and to summarize the underlying factors contributing to the current uncertainties. Initially, this article reviews the association between the n-6/n-3 fatty acid ratio and CVDs in different countries. A summary of the current understanding of the molecular mechanisms of n-6/n-3 fatty acid ratio on atherosclerosis is then given, including inflammatory responses, lipid metabolism, low-density lipoprotein cholesterol oxidation, and vascular function. Possible reasons behind the current controversies on the relationship between the n-6/n-3 fatty acid ratio and atherosclerosis are then provided, including the precise molecular structures of the fatty acids, diet-gene interactions, the role of fat-soluble phytochemicals, and the impact of other nutritional factors. An important objective of this article is to highlight areas where further research is needed to clarify the role of n-6/n-3 fatty acid ratio on atherosclerosis.

Avoiding implant-related complications in medically compromised patients with or without unhealthy lifestyle/Elevated oxidative stress

Increased human life expectancy broadens the alternatives for missing teeth and played a role in the widespread use of dental implants and related augmentation procedures for the aging population. Though, many of these patients may have one or more diseases. These systemic conditions may directly lead to surgical complications, compromise implant/bone healing, or influence long-term peri-implant health and its response to biologic nuisances. Offering patients credible expectations regarding intra- and postoperative complications and therapeutic prognosis is an ethical and legal obligation. Clear identification of potential types of adverse effects, complications, or errors is important for decision-making processes as they may be related to different local, systemic, and technical aspects. Therefore, the present review structures the underlying biological mechanisms, clinical evidence, and clinical recommendations for the most common systemic risk factors for implant-related complications.

Applications of Antioxidants in Dental Procedures

As people are paying more and more attention to dental health, various dental treatment procedures have emerged, such as tooth bleaching, dental implants, and dental restorations. However, a large number of free radicals are typically produced during the dental procedures. When the imbalance in distribution of reactive oxygen species (ROS) is induced, oxidative stress coupled with oxidative damage occurs. Oral inflammations such as those in periodontitis and pulpitis are also unavoidable. Therefore, the applications of exogenous antioxidants in oral environment have been proposed. In this article, the origin of ROS during dental procedures, the types of antioxidants, and their working mechanisms are reviewed. Additionally, antioxidants delivery in the complicated dental procedures and their feasibility for clinical applications are also covered. Finally, the importance of safety assessment of these materials and future work to take the challenge in antioxidants development are proposed for perspective.

Short-Term Effects of Supplemental L-Arginine, Diosmin, Troxerutin, and Hesperidin in Diabetic Patients: A Pilot Study

Background and Aims

Inflammatory, oxidative stress, and endothelial dysfunction play a key role in the pathogenesis of long-term cardiovascular complications in patients with diabetes. The present observational prospective study is aimed at evaluating the effects of micronutrients and phytochemicals contained in the dietary supplement Flebotrofine® (AMNOL Chimica Biologica) on biochemical markers of inflammation, endothelial dysfunction, and glycemic control in patients with diabetes.

Methods

105 type 1 or type 2 diabetes patients regularly took a daily dose of the dietary supplement Flebotrofine® for three consecutive months, and haematological and biochemical parameters were checked at baseline, after three months of treatment, and one month after its suspension. Statistical comparison of the laboratory parameters was performed using the two-tailed ANOVA test for repeated samples with a statistical significance level set at p < 0.05.

Results

The daily use of Flebotrofine® did not change the glycemic metabolic compensation of enrolled patients. After three months of regular Flebotrofine® intake, the plasma levels of the antioxidant β-carotene and of arginine were significantly higher compared with the baseline values, with a decrease in the ADMA/arginine ratio. In contrast, apolipoprotein B, ApoB/ApoA1 ratio, and platelet and leukocyte counts significantly dropped.

Conclusion

The daily use of Flebotrofine® might be a valid supplement of arginine, the precursor of NO, and essential in the prevention of endothelial dysfunction. The regular intake of arginine and phytochemicals also improved the antioxidant and antithrombotic profile of enrolled patients. Therefore, Flebotrofine® could be a useful dietary supplement to prevent long-term complications in patients with diabetes.

Inhibitory effect on human platelet aggregation and coagulation and antioxidant activity of C. edulis Ker Gawl rhizome and its secondary metabolites

ETHNOPHARMACOLOGICAL RELEVANCE

Although Canna edulis Ker Gawl rhizome has been used in Traditional Vietnamese Medicine to prevent and treat heart diseases without thorough scientific evidence, limited intensive search for the bioactivities and useful substances has been done.

AIM OF THE STUDY

This study aims to investigate the antiplatelet aggregation, anticoagulant and antioxidant activity of extracts from C. edulis rhizome, separate and purify its compounds from the most active fraction and evaluate the antiplatelet aggregation, anticoagulant and antioxidant activity of isolated compounds.

MATERIALS AND METHODS

C. edulis rhizome was extracted with ethanol, then fractionated with n-hexane, ethyl acetate and water. The inhibitory effect on adenosine diphosphate- and collagen-induced human platelet aggregation was evaluated. Prothrombin time, activated partial thromboplastine time and thrombine time were measured to examine the anticoagulant activity. The free radical scavenging ability was assessed with DPPH and ABTS assays. The fraction that showed the most active was used to separate and purify compounds. The structures of compounds were elucidated by NMR and MS spectroscopic methods. Isolated compounds were also tested for antiplatelet, anticoagulant and antioxidant activity.

RESULTS

The ethyl acetate fraction showed the most potent antiplatelet aggregation, anticoagulant and antioxidant activity. Subsequent fractionation of this active fraction resulted in the isolation of seven known compounds: 5-hydroxy-6-methyl-2H-pyran-2-one (1), epimedokoreanone A (2), nepetoidin B (3), ferulic acid (4), caffeic acid (5), hydroxytyrosol (6), and 1H-indole-3-carboxaldehyde (7). Previous studies reported the antiplatelet, anticoagulant and antioxidant activity of ferulic acid (4), caffeic acid (5) and hydroxytyrosol (6) and the antioxidant activity of nepetoidin B (3). This study demonstrated that both epimedokoreanone A (2) and nepetoidine B (3) also exhibited good antiplatelet effect and epimedokoreanone A (2) also had effective anticoagulant and antioxidant activity, while 5-hydroxy-6-methyl-2H-pyran-2-one (1) showed weaker antiplatelet and antioxidant activity but no anticoagulant effect.

CONCLUSIONS

This is the first experimental study to demonstrate the potent dose-dependent antiplatelet aggregation, anticoagulant and antioxidant activity of C. edulis rhizome and its pure compounds, supporting the traditional use of this plant for the treatment of heart diseases. The C. edulis rhizome is a potential source of bioactive compounds or functional food for treatment and/or prevention of heart- and oxidative stress-related diseases and its bioactive compounds are good candidates for drug development of anti-thrombosis and antioxidant agents.

The Fungal Iron Chelator Desferricoprogen Inhibits Atherosclerotic Plaque Formation

Hemoglobin, heme and iron are implicated in the progression of atherosclerosis. Therefore, we investigated whether the hydrophobic fungal iron chelator siderophore, desferricoprogen (DFC) inhibits atherosclerosis. DFC reduced atherosclerotic plaque formation in ApoE^-/- mice on an atherogenic diet. It lowered the plasma level of oxidized LDL (oxLDL) and inhibited lipid peroxidation in aortic roots. The elevated collagen/elastin content and enhanced expression of adhesion molecule VCAM-1 were decreased. DFC diminished oxidation of Low-density Lipoprotein (LDL) and plaque lipids catalyzed by heme or hemoglobin. Formation of foam cells, uptake of oxLDL by macrophages, upregulation of CD36 and increased expression of TNF-α were reduced by DFC in macrophages. TNF-triggered endothelial cell activation (vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecules (ICAMs), E-selectin) and increased adhesion of monocytes to endothelium were attenuated. The increased endothelial permeability and intracellular gap formation provoked by TNF-α was also prevented by DFC. DFC acted as a cytoprotectant in endothelial cells and macrophages challenged with a lethal dose of oxLDL and lowered the expression of stress-responsive heme oxygenase-1 as sublethal dose was employed. Saturation of desferrisiderophore with iron led to the loss of the beneficial effects. We demonstrated that DFC accumulated within the atheromas of the aorta in ApoE^-/- mice. DFC represents a novel therapeutic approach to control the progression of atherosclerosis.

Lipoprotein Drug Delivery Vehicles for Cancer: Rationale and Reason

Lipoproteins are a family of naturally occurring macromolecular complexes consisting amphiphilic apoproteins, phospholipids, and neutral lipids. The physiological role of mammalian plasma lipoproteins is to transport their apolar cargo (primarily cholesterol and triglyceride) to their respective destinations through a highly organized ligand-receptor recognition system. Current day synthetic nanoparticle delivery systems attempt to accomplish this task; however, many only manage to achieve limited results. In recent years, many research labs have employed the use of lipoprotein or lipoprotein-like carriers to transport imaging agents or drugs to tumors. The purpose of this review is to highlight the pharmacologic, clinical, and molecular evidence for utilizing lipoprotein-based formulations and discuss their scientific rationale. To accomplish this task, evidence of dynamic drug interactions with circulating plasma lipoproteins are presented. This is followed by epidemiologic and molecular data describing the association between cholesterol and cancer.

Effects of Dried Apple Consumption on Body Composition, Serum Lipid Profile, Glucose Regulation, and Inflammatory Markers in Overweight and Obese Children

Consumption of fruits reduces the risk of chronic diseases such as cardiovascular disease; however, very few studies have investigated the effect of fruit consumption in overweight and obese children. We examined whether consuming dried apple as a snack is a practical solution for weight loss and improves body composition and metabolic markers. Thirty-eight overweight or obese children aged 10 to 16 years were randomly assigned to one of two groups consuming twice daily 120 kcal serving per day of either dried apple or a control snack (muffin) for 8 weeks. Body weight, height, waist circumference, and body composition were determined during an initial visit and after 8 weeks of intervention. Blood samples were collected to measure serum concentrations of blood lipids, glucose, insulin, proinsulin, total adiponectin, and C-reactive protein, as well as total antioxidant capacity and activity of glutathione peroxidase. Body weight increased in the muffin group (P = .01). BodPod and dual-energy X-ray absorptiometry showed that fat-free mass increased (P < .05) only in the muffin group. High-density lipoprotein cholesterol concentration increased (P = .04) after the 8-week treatment within the apple group. Overall, minor differences were detected in growing children who consumed snacks of either dried apples or muffins with similar macronutrient profiles for 8 weeks. Future research should evaluate the effects of consuming fresh apples that include the peel.

Objective diagnosis of post-stroke depression using NMR-based plasma metabonomics

Background: Post-stroke depression (PSD) is a frequent and serious complication of stroke. However, the underlying molecular basis of PSD remains largely unknown, and no empirical laboratory tests were available to diagnose this disorder. Materials and methods: A proton nuclear magnetic resonance (¹H NMR)-based metabonomic approach was employed to profile plasma samples from 32 PSD, 35 stroke patients and 35 healthy comparison subjects (the training set) in order to identify metabolite biomarkers for PSD. Then, 10 PSD, 11 stroke patients and 11 healthy comparison subjects (test set) were used to validate the diagnostic performance of these biomarkers. Results: The multivariate statistical analysis demonstrated that PSD group was significantly distinguishable from non-PSD groups (non-depression stroke patients and healthy comparison group). Five plasma metabolites (phenylalanine, tyrosine, 1-methylhistidine, 3-methylhistidine and LDL CH3-(CH2)n-) were identified responsible for distinguishing PSD from non-PSD subjects. These metabolites were mainly involved in neurotransmitter metabolism and oxidative stress. The biomarker panel composing of these metabolites was capable of distinguishing test samples with a sensitivity of 100.0% and a specificity of 95.5%. Conclusion: Our findings suggest that plasma disturbances of neurotransmitter levels and oxidative stress were implicated in the onset of PSD; these disturbed metabolites biomarkers facilitate to the development of diagnostic tool for PSD.

Selected Molecular Mechanisms Involved in the Parasite⁻Host System Hymenolepis diminuta⁻Rattus norvegicus

The rat tapeworm Hymenolepis diminuta is a parasite of the small intestine of rodents (mainly mice and rats), and accidentally humans. It is classified as a non-invasive tapeworm due to the lack of hooks on the tapeworm’s scolex, which could cause mechanical damage to host tissues. However, many studies have shown that metabolites secreted by H. diminuta interfere with the functioning of the host’s gastrointestinal tract, causing an increase in salivary secretion, suppression of gastric acid secretion, and an increase in the trypsin activity in the duodenum chyme. Our work presents the biochemical and molecular mechanisms of a parasite-host interaction, including the influence on ion transport and host intestinal microflora, morphology and biochemical parameters of blood, secretion of antioxidant enzymes, expression of Toll-like receptors, mechanisms of immune response, as well as the expression and activity of cyclooxygenases. We emphasize the interrelations between the parasite and the host at the cellular level resulting from the direct impact of the parasite as well as host defense reactions that lead to changes in the host’s tissues and organs.

Low-density lipoprotein oxidation biomarkers in human health and disease and effects of bioactive compounds

Based on the significance of oxidized low-density lipoprotein (LDL) in health and disease, this review focuses on human studies addressing oxidation of LDL, including three lines of biomarkers, (i) ex vivo LDL resistance to oxidation, a "challenge test" model, (ii) circulating oxidized LDL, indicating the "current in vivo status", and (iii) autoantibodies against oxidized LDL as fingerprints of an immune response to oxidized LDL, along with circulating oxysterols and 4-hydroxynonenal as biomarkers of lipid peroxidation. Lipid peroxidation and oxidized LDL are hallmarks in the development of various metabolic, cardiovascular and other diseases. Changes further occur across life stages from infancy to older age as well as in athletes and smokers. Given their responsiveness to targeted nutritional interventions, markers of LDL oxidation have been employed in a rapidly growing number of human studies for more than 2 decades. There is growing interest in foods, which, besides providing energy and nutrients, exert beneficial effects on human health, such as protection of DNA, proteins and lipids from oxidative damage. Any health claim, however, needs to be substantiated by supportive evidence derived from human studies, using reliable biomarkers to demonstrate such beneficial effects. A large body of evidence has accumulated, demonstrating protection of LDL from oxidation by bioactive food compounds, including vitamins, other micronutrients and secondary plant ingredients, which will facilitate the selection of oxidation biomarkers for future human intervention studies and health claim support.

Decreased Antioxidant Vitamin Concentration May Be a Risk Factor for Recurrent Carotid Stenosis

Carotid endarterectomy has been found to be associated with a transient increase in systemic oxidative stress, and this has been shown to be a predictor of restenosis. The aim of this study was to determine the incidence of early recurrent stenosis and investigate a possible role of oxidative stress in its development by measuring the concentration of antioxidant vitamins. Patients undergoing carotid endarterectomy between August 2001 and February 2003 were included in the study. A preoperative blood sample was analyzed for antioxidant vitamin concentrations. All patients were followed up by duplex scans 3 and 12 months postoperatively. Ninety-three patients (101 carotid endarterectomies) were recruited. Nine arteries had developed restenosis by 12 months. Those patients who developed recurrent stenosis had significantly lower vitamin C concentrations (19.10 ± 3.69 vs 30.11 ± 19.10, P = .02) than those who did not. This study suggests that low antioxidant vitamin levels may predispose to early restenosis after carotid endarterectomy.

Hen Egg as an Antioxidant Food Commodity: A Review

Intake of antioxidants through diet is known to be important in reducing oxidative damage in cells and improving human health. Although eggs are known for their exceptional, nutritional quality, they are not generally considered as antioxidant foods. This review aims to establish the importance of eggs as an antioxidant food by summarizing the current knowledge on egg-derived antioxidants. Eggs have various natural occurring compounds including the proteins ovalbumin, ovotransferrin and lysozyme in egg white, as well as phosvitin, carotenoids and free aromatic amino acids in egg yolk. Some lipophilic antioxidants such as vitamin E, carotenoids, selenium, iodine and others can be transferred from feed into egg yolk to produce antioxidant-enriched eggs. The bioactivity of egg antioxidants can be affected by food processing, storage and gastrointestinal digestion. Generally thermal processing methods can promote loss of antioxidant properties in eggs due to oxidation and degradation, whereas gastrointestinal digestion enhances the antioxidant properties, due to the formation of new antioxidants (free amino acids and peptides). In summary, in addition to its well-known nutritional contribution to our diet, this review emphasizes the role of eggs as an important antioxidant food.

HDL and atherothrombotic vascular disease

High-density lipoproteins (HDLs) exert many beneficial effects which may help to protect against the development or progression of atherosclerosis or even facilitate lesion regression. These activities include promoting cellular cholesterol efflux, protecting low-density lipoproteins (LDLs) from modification, preserving endothelial function, as well as anti-inflammatory and antithrombotic effects. However, questions remain about the relative importance of these activities for atheroprotection. Furthermore, the many molecules (both lipids and proteins) associated with HDLs exert both distinct and overlapping activities, which may be compromised by inflammatory conditions, resulting in either loss of function or even gain of dysfunction. This complexity of HDL functionality has so far precluded elucidation of distinct structure-function relationships for HDL or its components. A better understanding of HDL metabolism and structure-function relationships is therefore crucial to exploit HDLs and its associated components and cellular pathways as potential targets for anti-atherosclerotic therapies and diagnostic markers.

Why fish oil fails: a comprehensive 21st century lipids-based physiologic analysis

The medical community suffered three significant fish oil failures/setbacks in 2013. Claims that fish oil's EPA/DHA would stop the progression of heart disease were crushed when The Risk and Prevention Study Collaborative Group (Italy) released a conclusive negative finding regarding fish oil for those patients with high risk factors but no previous myocardial infarction. Fish oil failed in all measures of CVD prevention-both primary and secondary. Another major 2013 setback occurred when fish oil's DHA was shown to significantly increase prostate cancer in men, in particular, high-grade prostate cancer, in the Selenium and Vitamin E Cancer Prevention Trial (SELECT) analysis by Brasky et al. Another monumental failure occurred in 2013 whereby fish oil's EPA/DHA failed to improve macular degeneration. In 2010, fish oil's EPA/DHA failed to help Alzheimer's victims, even those with low DHA levels. These are by no means isolated failures. The promise of fish oil and its so-called active ingredients EPA / DHA fails time and time again in clinical trials. This lipids-based physiologic review will explain precisely why there should have never been expectation for success. This review will focus on underpublicized lipid science with a focus on physiology.

Physical activity affects plasma coenzyme Q10 levels differently in young and old humans

Coenzyme Q (Q) is a key lipidic compound for cell bioenergetics and membrane antioxidant activities. It has been shown that also has a central role in the prevention of oxidation of plasma lipoproteins. Q has been associated with the prevention of cholesterol oxidation and several aging-related diseases. However, to date no clear data on the levels of plasma Q during aging are available. We have measured the levels of plasmatic Q10 and cholesterol in young and old individuals showing different degrees of physical activity. Our results indicate that plasma Q10 levels in old people are higher that the levels found in young people. Our analysis also indicates that there is no a relationship between the degree of physical activity and Q10 levels when the general population is studied. However, very interestingly, we have found a different tendency between Q10 levels and physical activity depending on the age of individuals. In young people, higher activity correlates with lower Q10 levels in plasma whereas in older adults this ratio changes and higher activity is related to higher plasma Q10 levels and higher Q10/Chol ratios. Higher Q10 levels in plasma are related to lower lipoperoxidation and oxidized LDL levels in elderly people. Our results highlight the importance of life habits in the analysis of Q10 in plasma and indicate that the practice of physical activity at old age can improve antioxidant capacity in plasma and help to prevent cardiovascular diseases.

Evaluation of the antioxidant and anti-glication effects of the hexane extract from Piper auritum leaves in vitro and beneficial activity on oxidative stress and advanced glycation end-product-mediated renal injury in streptozotocin-treated diabetic rats

The aim of this study was to investigate the antioxidant activity of hexane extracts from leaves of Piper auritum (HS). Eight complementary in vitro test methods were used, including inhibition of DPPH· radicals, nitric oxide, superoxide anion, ion-chelating, ABTS, oxygen radical absorbance capacity, β-carotene bleaching and peroxy radical scavenging. The results indicated that HS possesses high antioxidant activity. To add to these finding we tested the effect against oxidative stress in liver, pancreas and kidney in diabetic rats. Low levels of SOD, CAT, GPx and GSH in diabetic rats were reverted to near normal values after treatment with HS. These results suggest that P. auritum prevents oxidative stress, acting as a suppressor of liver cell damage. Given the link between glycation and oxidation, we proposed that HS might possess significant in vitro antiglycation activity. Our data confirmed the inhibitory effect of HS on bovine serum albumin, serum glycosylated protein, glycation of LDL, and glycation hemoglobin. The effect of HS on diabetic renal damage was investigated using streptozotocin-induced diabetic rats. The oral administration of HS at a dose of 200 and 400 mg/kg body weight/day for 28 days significantly reduced advanced glycation endproduct (AGE) formation, elevated renal glucose and thiobarbituric acid-reactive substance levels in the kidneys of diabetic rats. This implies that HS would alleviate the oxidative stress under diabetes through the inhibition of lipid peroxidation. These findings indicate that oxidative stress is increased in the diabetic rat kidney and that HS can prevent renal damage associated with diabetes by attenuating the oxidative stress.

L-NAME co-treatment prevent oxidative damage in the lung of adult Wistar rats treated with vitamin A supplementation

Based on the fact that vitamin A in clinical doses is a potent pro-oxidant agent to the lungs, we investigated here the role of nitric oxide (NO•) in the disturbances affecting the lung redox environment in vitamin A-treated rats (retinol palmitate, doses of 1000-9000 IU•kg(-1)•day(-1)) for 28 days. Lung mitochondrial function and redox parameters, such as lipid peroxidation, protein carbonylation and the level of 3-nytrotyrosine, were quantified. We observed, for the first time, that vitamin A supplementation increases the levels of 3-nytrotyrosine in rat lung mitochondria. To determine whether nitric oxide (NO •) or its derivatives such as peroxynitrite (ONOO-) was involved in this damage, animals were co-treated with the nitric oxide synthase inhibitor L-NAME (30 mg•kg(-1), four times a week), and we analysed if this treatment prevented (or minimized) the biochemical disturbances resulting from vitamin A supplementation. We observed that L-NAME inhibited some effects caused by vitamin A supplementation. Nonetheless, L-NAME was not able to reverse completely the negative effects triggered by vitamin A supplementation, indicating that other factors rather than only NO• or ONOO- exert a prominent role in mediating the redox effects in the lung of rats that received vitamin A supplementation.

The toxicity redox mechanisms of cadmium alone or together with copper and zinc homeostasis alteration: its redox biomarkers

Cadmium (Cd) is a toxic metal and can induce and/or promote diseases in humans (cancer, aging diseases, kidney and bone diseases, etc.). Its toxicity involves many mechanisms including the alteration of copper (Cu) and zinc (Zn) homeostasis leading to reactive oxygen species (ROS) production, either directly or through the inhibition of antioxidant activities. Importantly, ROS can induce oxidative damages in cells. Cadmium, Cu and Zn are also able to induce glutathione (GSH) and metallothioneins (MT) synthesis in a cell-type-dependent manner. As a consequence, the effects induced by these three metals result simultaneously from the inhibition of antioxidant activities and the induction of other factors such as GSH and MT synthesis. MT levels are regulated not only by the p53 protein in a cell-type-dependent manner, or by transcription factors such as metal-responsive transcription factor 1 (MTF-1) and cellular Zn levels but also by cellular GSH level. As described in the literature, DNA damage, GSH and MT levels are sensitive biomarkers used to identify Cd-induced toxicity alone or together with Cu and Zn homeostasis alteration.

Antioxidant and signal modulation properties of plant polyphenols in controlling vascular inflammation

Oxidized low-density lipoproteins (oxLDL) play a critical role in the initiation of atherosclerosis through activation of inflammatory signaling. In the present work we investigated the role of antioxidant and signal modulation properties of plant polyphenols in controlling vascular inflammation. Significant decrease in intracellular NO level and superoxide overproduction was found in human umbilical vein endothelial cells (HUVEC) treated with oxLDL, but not with LDL. The redox imbalance was prevented by the addition of quercetin or resveratrol. Expression analysis of 14 genes associated with oxidative stress and inflammation revealed oxLDL-mediated up-regulation of genes specifically involved in leukocyte recruitment and adhesion. This up-regulation could be partially avoided by the addition of verbascoside or resveratrol, while treatment with quercetin resulted in a further increase in the expression of these genes. Lipopolysaccharide (LPS)-treated HUVEC were also used for the evaluation of anti-inflammatory potency of plant polyphenols. Significant differences between HUVEC treaded with oxLDL and LPS were found in both the expression pattern of inflammation-related genes and the effects of plant polyphenols on cellular responses. The present data indicate that plant polyphenols may affect vascular inflammation not only as antioxidants but also as modulators of inflammatory redox signaling pathways.

Free radicals, antioxidants and functional foods: Impact on human health

In recent years, there has been a great deal of attention toward the field of free radical chemistry. Free radicals reactive oxygen species and reactive nitrogen species are generated by our body by various endogenous systems, exposure to different physiochemical conditions or pathological states. A balance between free radicals and antioxidants is necessary for proper physiological function. If free radicals overwhelm the body's ability to regulate them, a condition known as oxidative stress ensues. Free radicals thus adversely alter lipids, proteins, and DNA and trigger a number of human diseases. Hence application of external source of antioxidants can assist in coping this oxidative stress. Synthetic antioxidants such as butylated hydroxytoluene and butylated hydroxyanisole have recently been reported to be dangerous for human health. Thus, the search for effective, nontoxic natural compounds with antioxidative activity has been intensified in recent years. The present review provides a brief overview on oxidative stress mediated cellular damages and role of dietary antioxidants as functional foods in the management of human diseases.

SOD3 R231G polymorphism associated with coronary artery disease and myocardial infarction. The Ludwigshafen Risk and Cardiovascular Health (LURIC) study

This study examined the superoxide dismutase 3 (SOD3) R231G polymorphism in relation to the severity of coronary artery disease (CAD) and the risk of myocardial infarction (MI) in 3211 individuals; 94.4% of study participants were homozygous for SOD3 231RR and 5.5% were heterozygous for SOD3 231RG. The odds ratios of the RG and GG genotype (adjusted for age, gender and for conventional cardiovascular risk factors) were 2.02 (95% CI, 1.23-3.33, p=0.005) for the highest vs the lowest Friesinger coronary score and 1.40 (95% CI, 1.02-1.92, p=0.037) for MI, respectively. Further the SOD3 RG and GG genotype was associated with lower alpha-tocopherol levels than the wild type SOD3 RR genotype. It is concluded that the SOD3 231RG and GG genotype is associated with lower alpha-tocopherol levels and the severity of CAD and the risk of MI.

Free and Peptide-bound DOPA Can Inhibit Initiation of Low Density Lipoprotein Oxidation

Hydroxyl radicals have been shown to convert free tyrosine to 3,4-dihydroxyphenyl-alanine (DOPA) which has reducing properties. During protein or peptide oxidation such reducing species are also formed from tyrosine residues. Free DOPA or peptide-bound DOPA (PB-DOPA) is able to promote radical-generating events, facilitating the damage of biomolecules such as nucleic acids. Radical induced lipid oxidation in low density lipoprotein (LDL) transforms the lipoprotein into an atherogenic particle. As PB-DOPA has been found in atherosclerotic plaques, we tested the ability of free and PB-DOPA to influence LDL oxidation. Free DOPA, in contrast to tyrosine had strong inhibitory action on both, the copper-ion initiated and metal ion independent (AAPH-induced) lipid oxidation. Free DOPA also inhibited LDL oxidation induced by the copper transport protein ceruloplasmin. To test if PB-DOPA was also able to inhibit LDL oxidation, DOPA residues were generated enzymatically in the model peptides insulin and tyr-tyr-tyr, respectively. PB-DOPA formation substantially increased the ability of both molecules to inhibit LDL oxidation by copper or AAPH. We hypothesize that DOPA-peptides and -proteins may have the potential to act as efficacious antioxidants in the atherosclerotic plaque.

Vitamins and cardiovascular disease

CVD is a major cause of mortality and morbidity in the Western world. In recent years its importance has expanded internationally and it is believed that by 2020 it will be the biggest cause of mortality in the world, emphasising the importance to prevent or minimise this increase. A beneficial role for vitamins in CVD has long been explored but the data are still inconsistent. While being supported by observational studies, randomised controlled trials have not yet supported a role for vitamins in primary or secondary prevention of CVD and have in some cases even indicated increased mortality in those with pre-existing late-stage atherosclerosis. The superiority of combination therapy over single supplementation has been suggested but this has not been confirmed in trials. Studies have indicated that beta-carotene mediates pro-oxidant effects and it has been suggested that its negative effects may diminish the beneficial effects mediated by the other vitamins in the supplementation cocktail. The trials that used a combination of vitamins that include beta-carotene have been disappointing. However, vitamin E and vitamin C have in combination shown long-term anti-atherogenic effects but their combined effect on clinical endpoints has been inconsistent. Studies also suggest that vitamins would be beneficial to individuals who are antioxidant-deficient or exposed to increased levels of oxidative stress, for example, smokers, diabetics and elderly patients, emphasising the importance of subgroup targeting. Through defining the right population group and the optimal vitamin combination we could potentially find a future role for vitamins in CVD.

Lipid metabolism and antioxidant status in sucrose vs. potato-fed rats

OBJECTIVE

Consumption of high levels of simple carbohydrates is associated with several metabolic disorders in humans and in laboratory animals, including symptoms of an early stage of metabolic syndrome (syndrome X). This disorder has several cardiovascular risk factors, such as hypertriglyceridemia, and is associated with an increase in oxidative stress. In contrast to sucrose, potato, a source of complex carbohydrates and antioxidant micronutrients, was thought to improve lipid metabolism and antioxidant protection.

METHODS

We investigated the effects of diets containing i) complex dietary carbohydrates and antioxidant micronutrients (potato Solanum tuberosum L.), ii) complex carbohydrates (starch) and iii) a simple carbohydrate (sucrose) on lipid metabolism and antioxidant status in rats.

RESULTS

An increase in short chain fatty acid (SCFA) pools was observed in the cecum of rats fed a potato-based diet, resulting from an increase in all SCFAs, especially propionate (+360%, P < 0.0001). Feeding rats a potato-based diet for 3 weeks led to a decrease in cholesterol (-37%, potato vs. control and -32%, potato vs. sucrose) and triglycerides (-31%, potato vs. control and -43%, potato vs. sucrose) concentrations in triglyceride-rich lipoproteins (TGRLP) fractions. The antioxidant status was decreased by sucrose consumption and improved by potato consumption.

CONCLUSIONS

Our present results suggest that consumption of complex carbohydrates (provided as cooked potatoes), in combination with different antioxidant micronutrients, may enhance the antioxidant defences and improve lipid metabolism, when compared with starch (complex carbohydrates) and to sucrose consumption (source of simple sugar). These effects limit oxidative stress and reduce the risk of developing the associated degenerative diseases, including cardiovascular disease, and could have potential in cardiovascular disease prevention.

Postprandial LDL phenolic content and LDL oxidation are modulated by olive oil phenolic compounds in humans

Olive oil phenolic compounds are potent antioxidants in vitro, but evidence for antioxidant action in vivo is controversial. We examined the role of the phenolic compounds from olive oil on postprandial oxidative stress and LDL antioxidant content. Oral fat loads of 40 mL of similar olive oils, but with high (366 mg/kg), moderate (164 mg/kg), and low (2.7 mg/kg) phenolic content, were administered to 12 healthy male volunteers in a cross-over study design after a washout period in which a strict antioxidant diet was followed. Tyrosol and hydroxytyrosol, phenolic compounds of olive oil, were dose-dependently absorbed (p<0.001). Total phenolic compounds in LDL increased at postprandial state in a direct relationship with the phenolic compounds content of the olive oil ingested (p<0.05). Plasma concentrations of tyrosol, hydroxytyrosol, and 3-O-methyl-hydroxytyrosol directly correlated with changes in the total phenolic compounds content of the LDL after the high phenolic compounds content olive oil ingestion. A 40 mL dose of olive oil promoted a postprandial oxidative stress, the degree of LDL oxidation being lower as the phenolic content of the olive oil administered increases. In conclusion, olive oil phenolic content seems to modulate the LDL phenolic content and the postprandial oxidative stress promoted by 40 mL olive oil ingestion in humans.

LDL susceptibility to oxidation and HDL antioxidant capacity in patients with renal failure

OBJECTIVES

This study examines the susceptibility to oxidation and the ability to stimulate reactive oxygen species of LDL from hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) patients. It was also designed to evaluate the antioxidant activity of HDL from uremic patients.

DESIGN AND METHODS

Lipoprotein properties were determined in 28 HD patients, 30 CAPD patients and 30 control subjects by spectrophotometric, chemiluminescence and electrophoresis methods.

RESULTS

CAPD LDL were more resistant to oxidation than control LDL. HD and control LDL, in contrast to CAPD LDL, stimulated reactive oxygen species generation in granulocytes. The HDL ability to protect LDL against oxidation was impaired in renal patients.

CONCLUSIONS

The risk of atherosclerosis development in patients with renal failure does not appear to be related to less resistance of LDL to oxidation, but rather to the decreased HDL antioxidant capacity.

Kinetics of Fatty Acid Oxidation in Low Density Lipoproteins Evaluated by Registration of the Oxidizer Consumption and Reaction Product Yield

Oxidation of arachidonic acid by ROS in vitro can be evaluated by the formation of reaction products (conjugated dienes); this is preceded by a lag period caused by the action of antioxidants (alpha-tocopherol, beta-carotene, and ascorbic acid). In case of ozone titration the oxidizer is consumed even during the lag period, when conjugated dienes are not yet forming. Comparison of the oxidation rate constants for antioxidants, arachidonic and oleic monoenic fatty acids suggests that during the lag period Cu(2+)-initiated forms of O(2) oxidize primarily oleic acid, whose reaction rate constant is much higher than those of antioxidants. Presumably, the duration of lag period during oxidation of arachidonic acid and formation of conjugated dienes is determined also by the content of triglycerides and oleic fatty acid in low density lipoproteins.

Role of bilirubin, vitamin C and ceruloplasmin as antioxidants in coronary artery disease [CAD]

A study has been carried out on 250 CAD patients to see how the serum levels of three antioxidants i.e., Vitamin C, Bilirubin and Ceruloplasmin are related to the CAD risk factors and characteristics in these patients. The number of severe category CAD patients declined by 7-18% with increasing serum levels of the three antioxidants and, triple vessel disease declined by 14-20%. A decline of 39% in Myocardial Infarction (MI) occurred with increasing serum Ceruloplasmin. Serum Ceruloplasmin was significantly lower in the MI group compared to the non MI group CAD patients. There was a steady and a significant decline in the mean values of serum levels of cholesterol, Triglyceride, VLDL cholesterol along with BMI with increasing serum level. The study indicates that with increasing serum levels of the three antioxidants studied, the % MI along with % Triple vessel disease and severity of CAD goes down suggesting that the modifiable risk factors have to be suitably modified in order to maintain a reasonably high level of these antioxidants, as the risk factors are inversely related to the serum antioxidant levels.

Verminderung der Lipidperoxidation und der Apoptoserate in kornealen Endothelzellen durch Vitamin A

PURPOSE

The goal of this study was to determine the effects of lipid peroxidation-mediated toxicity of iron ions on corneal endothelial cells leading to apoptosis.

METHODS

Murine corneal endothelial cells were maintained in tissue culture medium supplemented with free iron ions, known to lead to increased lipid peroxidation. Retinoic acid in the cell supernatant and cytoplasm of these cells was determined using HPLC. The rate of apoptosis was assessed by quantification of caspase-3-like activity. The lipid peroxidation was measured using the malondialdehyde method. Supplementation of retinoic acid was tested in the setting of apoptosis.

RESULTS

Free iron ions led to a rapid loss of retinoic acid in the supernatant and the corneal endothelial cells. This was correlated with rising levels of malondialdehyde following oxidative stress and increased apoptosis. Supplementation of retinoic acid alone significantly reduced oxidative stress and apoptosis in the respective cells.

CONCLUSION

In this study the authors present a novel in vitro model to test the direct influence of pro-oxidative species on corneal endothelial cells. The authors also prove that supplementing corneal endothelial cells with retinoic acid sufficiently prevents free radical injury and apoptosis.

Anti-oxidative vitamins prevent lipid-peroxidation and apoptosis in corneal endothelial cells

To determine the effects of vitamin supplementation on the lipid-peroxidation-mediated toxicity of iron-ions on corneal endothelial cells (CECs) leading to apoptosis, murine CECs were maintained in tissue culture medium supplemented with increasing concentrations of free iron-ions, a treatment known to lead to increased lipid-peroxidation. The concentration of anti-oxidative vitamins (ascorbic acid, tocopherol and retinoic acid) in the cell supernatant and in the cells was determined by high-pressure liquid chromatography. Apoptosis was assessed by quantification of caspase-3-like activity and by using annexin-V/propidium iodide stains for flow cytometry. Lipid-peroxidation was measured by the malondialdehyde method. Supplementation with anti-oxidative vitamins was tested for the ability to counteract the induction of apoptosis. The production of nitric oxide was assessed spectrophotometrically and the expression levels of inducible and endothelial nitric oxide synthase were determined by Western blot. Increasing levels of free iron led to a rapid loss of anti-oxidative vitamins in the supernatant and in the CECs. This was correlated with rising levels of malondialdehyde and increased apoptosis. Supplementation with ascorbic acid or alpha-tocopherol alone did not prevent lipid-peroxidation in the cells. A combination of vitamins C and E (ascorbic acid, tocopherol) or solitary supplementation with vitamin A (retinoic acid) prevented lipid-peroxidation. We thus present a novel in vitro model for testing the direct influence of pro-oxidative species on CECs. We also show that supplementation with anti-oxidative vitamins to CECs significantly prevents the generation of free-radical-induced oxidative injury and apoptosis. These findings may have important implications for the storage of human corneae prior to transplantation and for the prolongation of corneal graft survival.

The influence of dietary vitamin E, fat, and methionine on blood cholesterol profile, homocysteine levels, and oxidizability of low density lipoprotein in the gerbil

A 90-day feeding study with gerbils was conducted to evaluate the influence of dietary vitamin E levels (25 mg/kg diet, 75 mg/kg, 300 mg/kg, and 900 mg/kg), two levels of dietary methionione (casein or casein+L-methionine (1% w/w)) and two sources of lipid (soybean oil [20%] or soybean oil [4%]+coconut oil [16%, 1:4 w/w]) upon serum lipids (total cholesterol, HDL-cholesterol, LDL-cholesterol). In addition, this study examined the effects of diet-induced hyperhomocysteinemia and supplemental dietary vitamin E on the oxidation of low density lipoproteins. Tissue vitamin E (heart, liver, and plasma) demonstrated a dose response (P< or =0.001) following the supplementation with increasing dietary vitamin E (25, 75, 300, and 900 mg/kg). In addition, tissue vitamin E levels were found to be higher (P< or =0.001) in those animals receiving a combination of coconut oil+soybean oil as compared to the group receiving soybean oil solely. Blood cholesterol profiles indicated an increase (P< or =0.001) in total cholesterol and LDL cholesterol by the influence of saturated fat and supplemental methionine. Low-density lipoprotein cholesterol profile demonstrated a reduction (P< or =0.001) at the higher dietary vitamin E levels (300 and 900 mg/kg) as compared to the 25 mg/kg and 75 mg/kg dietary vitamin E. Plasma protein carbonyls were not influenced by dietary vitamin E nor by supplemental methionine intake. In vitro oxidation of LDL showed that vitamin E delayed the lag time of the oxidation phase (P< or =0.001) and reduced total diene production (P< or =0.001). On the contrary, supplemental methionine decreased (P< or =0.001) the delay time of the lag phase, whereas total diene production was increased (P< or =0.001). Plasma lipid hydroperoxides were significantly reduced (P< or =0.05) with supplemental dietary vitamin E, whereas supplemental L-methionine (1%) resulted in a significant (P< or =0.05) increase in lipid plasma hydroperoxide formation. Plasma homocysteine was elevated (P< or =0.001) with supplemental dietary L-methionine (1%) as well as the inclusion of dietary saturated fat. The present data showed that 1) a combination of dietary lipids (saturated and unsaturated fatty acids) as well as vitamin E and methionine supplementation altered blood cholesterol lipoprotein profiles; 2) in vitro oxidation parameters including LDL (lag time and diene production) and plasma hydroperoxide formations were affected by vitamin E and methionine supplementation; and 3) plasma homocysteine concentrations were influenced by supplemental methionine and the inclusion of dietary saturated fat.

LDL Susceptibility to Copper-Induced Oxidation after Administration of a Single Dose of Free or Esterified Beta-Cryptoxanthin

BACKGROUND

The oxidative modification of LDL is believed to be an initial step in atherosclerosis. Thus, antioxidative substances such as carotenoids may have a role in the prevention of coronary heart disease. We examined the susceptibility of LDL to Cu2+ oxidation in young adults before and after a single dose of beta-cryptoxanthin.

METHODS

1.3 mg of beta-cryptoxanthin was administered to 12 apparently healthy young volunteers. Six of the volunteers received esters, the other six free beta-cryptoxanthin. The plasma concentration of beta-cryptoxanthin and the susceptibility of LDL to copper-induced oxidation ex vivo in terms of the duration of lag time were measured before and 12 h after beta-cryptoxanthin ingestion.

RESULTS

A single dose of beta-cryptoxanthin significantly increased the mean plasma beta-cryptoxanthin concentration and the mean cholesterol adjusted beta-cryptoxanthin concentration by 117 and 133%, respectively. No effect on the length of lag time was assessed. However, in LDL isolated from plasma 12 h after beta-cryptoxanthin administration the lengths of lag time correlated significantly with the plasma beta-cryptoxanthin concentration and with the cholesterol adjusted beta-cryptoxanthin levels. The lag time did not differ significantly between volunteers who received esters and those who received the same dosage as free beta-cryptoxanthin. At both measuring points, smokers, male volunteers and women using oral contraceptives tended to exhibit lower beta-cryptoxanthin concentrations and lower cholesterol adjusted beta-cryptoxanthin concentrations as well as increased LDL oxidizability compared to nonsmokers and women not using oral contraceptives.

CONCLUSION

A single dose of beta-cryptoxanthin does not enhance the duration of LDL lag time ex vivo in healthy young subjects.

Inhibition of Platelet Adherence to Mononuclear Cells by α-Tocopherol

BACKGROUND

Platelet-leukocyte interaction is an early important event for thrombogenesis, and this process is mainly mediated by P-selectin on platelets. Although alpha-tocopherol has been shown to inhibit thrombotic disorders, the effect of alpha-tocopherol on platelet P-selectin expression and platelet-leukocyte interaction is little known.

METHODS AND RESULTS

We examined whether alpha-tocopherol inhibited human platelet P-selectin expression and platelet-leukocyte interaction. Alpha-tocopherol (50 to 500 microg/mL) inhibited thrombin-induced or phorbol 12-myristate 13-acetate (PMA)-induced P-selectin expression on platelets. alpha-Tocopherol suppressed platelet-mononuclear cell (MNC) interaction, platelet aggregation, and platelet protein kinase C (PKC) activity stimulated with either PMA (100 nmol/L) or thrombin. Inhibitory actions of alpha-tocopherol against the platelet functions were mimicked by staurosporine, a selective PKC inhibitor. After oral supplementation of alpha-tocopherol (300 mg/d for 3 weeks) in healthy subjects, thrombin-mediated or PMA-mediated P-selectin expression, platelet-MNC interaction, and platelet aggregation ex vivo were suppressed.

CONCLUSIONS

alpha-Tocopherol inhibited P-selectin expression on human platelets and thereby attenuated platelet-MNC interactions, which were mediated at least in part by the inhibition of intraplatelet PKC activity. These actions of alpha-tocopherol on platelet functions provide new insights into the antithromboatherogenic properties of alpha-tocopherol.

Copper-mediated LDL oxidation by homocysteine and related compounds depends largely on copper ligation

Oxidation of low-density lipoprotein (LDL) is thought to be a major factor in the pathophysiology of atherosclerosis. Elevated plasma homocysteine is an accepted risk factor for atherosclerosis, and may act through LDL oxidation, although this is controversial. In this study, homocysteine at physiological concentrations is shown to act as a pro-oxidant for three stages of copper-mediated LDL oxidation (initiation, conjugated diene formation and aldehyde formation), whereas at high concentration, it acts as an antioxidant. The affinity for copper of homocysteine and related copper ligands homocysteine, cystathionine and djenkolate was measured, showing that at high concentrations (100 microM) under our assay conditions, they bind essentially all of the copper present. This is used to rationalise the behaviour of these ligands, which stimulate LDL oxidation at low concentration but generally inhibit it at high concentration. Albumin strongly reduced the effect of homocystine on lag time for LDL oxidation, suggesting that the effects of homocystine are due to copper binding. In contrast, copper binding does not fully explain the pro-oxidant behaviour of low concentrations of homocysteine towards LDL, which appears in part at least to be due to stimulation of free radical production. The likely role of homocysteine in LDL oxidation in vivo is discussed in the light of these results.

Role of beta2-glycoprotein I, LDL-, and antioxidant levels in hypercholesterolemic elderly subjects

The levels of electronegative low-density lipoprotein (LDL-), LDL cholesterol oxidability, and plasma levels of molecular antioxidants and of beta(2)-glycoprotein I (beta(2) GPI) were studied in a group of 10 hypercholesterolemic (HC) and 10 normocholesterolemic (NC) elderly subjects. HC subjects showed significantly higher levels of cholesterol, LDL cholesterol, LDL-, and beta(2)GPI than NC, whereas high-density lipoprotein cholesterol and alpha-tocopherol levels were lower in HC as compared with NC subjects. Correlations among LDL- levels, LDL oxidation lag time, beta(2)GPI, and antioxidant plasma levels were studied in 100 HC elderly subjects. Lag time for in vitro LDL oxidation positively correlated with ubiquinol-10 levels (p = 0.008), but not with other antioxidants studied or beta(2)GPI. LDL- and alpha-tocopherol levels showed an inverse and significant correlation (p = 0.018). beta(2)GPI and LDL cholesterol levels were correlated (p = 0.001), whereas no significance was found between LDL- and beta(2)GPI levels (p = 0.057). The physiological significance of alpha-tocopherol and ubiquinol-10 levels on LDL- levels, and the presence of high levels of beta(2)-GPI, are discussed in terms of protective mechanisms operating during the overall atherosclerosis process.

Long-term effect of combined vitamins E and C on coronary and peripheral endothelial function

OBJECTIVES

We tested whether long-term administration of antioxidant vitamins C and E improves coronary and brachial artery endothelial function in patients with coronary artery disease (CAD).

BACKGROUND

Endothelial function is a sensitive indicator of vascular health. Oxidant stress and oxidized low-density lipoprotein (LDL) impair endothelial function by reducing nitric oxide bioavailability in the artery wall.

METHODS

We randomly assigned 30 subjects with CAD to combined vitamin E (800 IU per day) and C (1000 mg per day) or to placebos in a double-blind trial. Coronary artery endothelial function was measured as the change in coronary artery diameter to acetylcholine infusions (n = 18 patients), and brachial artery endothelial function was assessed by flow-mediated dilation (n = 25 patients) at baseline and six months. Plasma markers of oxidant stress (oxidized LDL and autoantibodies) were also measured.

RESULTS

Plasma alpha-tocopherol (p < 0.001) and ascorbic acid (p < 0.02) increased with active therapy. Compared to placebo, there was no improvement in coronary and brachial endothelial vasomotor function over six months. Although vitamins C and E tended to reduce F2-isoprostanes (p = 0.065), they failed to alter oxidized LDL or autoantibodies to oxidized LDL.

CONCLUSIONS

Long-term oral vitamins C and E do not improve key mechanisms in the biology of atherosclerosis or endothelial dysfunction, or reduce LDL oxidation in vivo.

Improvement of serum oxidation by pravastatin might be one of the mechanisms by which endothelial function in dilated coronary artery segments is ameliorated

BACKGROUND

Oxidation susceptibility of lipids in vitro is considered to reflect the exposure of lipids to oxidation stress in vivo which is related to cardiovascular morbidity. This study examined the effect of pravastatin therapy on serum oxidation susceptibility, particularly in relation to endothelial function of coronary arteries.

METHODS

The participants were recruited from the Pravastatin-Related Effects Following Angioplasty on Coronary Endothelium trial, a double-blinded, placebo-controlled, randomized, multi-center study designed to analyze the effect of pravastatin treatment on endothelial function in previously dilated and normal coronary arteries. Serial, graded, intra-coronary acetylcholine infusions were used to assess endothelial function. In vitro, copper-induced, serum oxidation parameters were determined at randomization and at time of coronary endothelial function assessment.

RESULTS

Oxidation parameters were determined in 45 patients (pravastatin 23, placebo 22). Pravastatin therapy significantly improved serum oxidation lag time (+8%, P<0.05), maximal diene formation rate (-22%, P<0.01) and total amount of dienes formed after 5 h (-16%, P<0.01). These parameters remained essentially unchanged in the placebo group. Acetylcholine-evoked responses were positively correlated to therapy-induced change in serum oxidation susceptibility in the dilated segment group (r2=0.56, P=0.006).

CONCLUSION

Pravastatin's beneficial effect on endothelial dysfunction of dilated coronary segments may be secondary to pravastatin's improvement of oxidation susceptibility.

Vitamin C and risk of coronary heart disease in women

OBJECTIVES

Our objective was to prospectively examine the relation between vitamin C intake and risk of coronary heart disease (CHD) in women.

BACKGROUND

Results from prospective investigations of the relation between vitamin C intake and risk of CHD have been inconsistent. The lack of clear evidence for a protective association despite a plausible mechanism indicates the need to evaluate further the association between vitamin C intake and risk of CHD.

METHODS

In 1980, 85,118 female nurses completed a detailed semiquantitative food-frequency questionnaire that assessed their consumption of vitamin C and other nutrients. Nurses were followed up for 16 years for the development of incident CHD (nonfatal myocardial infarction and fatal CHD).

RESULTS

During 16 years of follow-up (1,240,566 person-years), we identified 1,356 incident cases of CHD. After adjustment for age, smoking, and a variety of other coronary risk factors, we observed a modest significant inverse association between total intake of vitamin C and risk of CHD (relative risk [RR] = 0.73; 95% confidence interval [CI] 0.57 to 0.94). Among women who did not use vitamin C supplements or multivitamins, the association between intake of vitamin C from diet alone and incidence of CHD was weak and not significant (RR = 0.86; 95% CI 0.59 to 1.26). In multivariate models adjusting for age, smoking, and a variety of other coronary risk factors, vitamin C supplement use was associated with a significantly lower risk of CHD (RR = 0.72; 95% CI 0.61 to 0.86).

CONCLUSIONS

Users of vitamin C supplements appear to be at lower risk for CHD.

Dietary carotenoids and risk of coronary artery disease in women

BACKGROUND

Numerous studies have shown that higher intakes or higher blood concentrations of carotenes are associated with a lower risk of coronary artery disease (CAD). Given the null results in trials of beta-carotene supplementation, considerable attention has focused on the potential role of other dietary carotenoids in the prevention of CAD.

OBJECTIVE

Our objective was to prospectively examine the relation between dietary intakes of specific carotenoids and risk of CAD in women.

DESIGN

In 1984, 73 286 female nurses completed a semiquantitative food-frequency questionnaire that assessed their consumption of carotenoids and various other nutrients. The women were followed for 12 y for the development of incident CAD (nonfatal myocardial infarction and fatal CAD), and dietary information was updated in 1986, 1990, and 1994.

RESULTS

During 12 y of follow-up (803 590 person-years), we identified 998 incident cases of CAD. After adjustment for age, smoking, and other CAD risk factors, we observed modest but significant inverse associations between the highest quintiles of intake of beta-carotene and alpha-carotene and risk of CAD but no significant relation with intakes of lutein/zeaxanthin, lycopene, or beta-cryptoxanthin. For women in the highest compared with the respective lowest quintile of intake, the relative risks for beta-carotene and alpha-carotene were 0.74 (95% CI: 0.59, 0.93) and 0.80 (95% CI: 0.65, 0.99), respectively. The association between the specific carotenoids and CAD risk did not vary significantly by current smoking status.

CONCLUSION

Higher intakes of foods rich in alpha-carotene or beta-carotene are associated with a reduction in risk of CAD.

Juice and phenolic fractions of the berry Aristotelia chilensis inhibit LDL oxidation in vitro and protect human endothelial cells against oxidative stress

Oxidative modification of low-density lipoprotein (LDL) particles is a key event in the development of atherosclerosis. Oxidized LDL induces oxidative stress and modifies gene expression in endothelial cells. Berries constitute a rich dietary source of phenolic antioxidants. We found that the endemic Chilean berry Aristotelia chilensis (ach) has higher phenol content and scores better for total radical-trapping potential and total antioxidant reactivity in in vitro antioxidant capacity tests, when compared to different commercial berries. The juice of ach is also effective in inhibiting copper-induced LDL oxidation. In human endothelial cell cultures, the addition of ach juice significantly protects from hydrogen peroxide-induced intracellular oxidative stress and is dose-dependent. The aqueous, anthocyanin-rich fraction of ach juice accounts for most of ach's antioxidant properties. These results show that ach is a rich source of phenolics with high antioxidant capacity and suggest that it may have antiatherogenic properties.

Assay methods of modified lipoproteins in plasma

Modified lipoproteins, especially oxidatively modified low-density lipoprotein (Ox-LDL), are present in the plasma of patients with atherosclerosis and related diseases. The modification of LDL is believed to play an important role in the development of atherosclerosis. Thus, measurement of plasma Ox-LDL is essential not only for investigating its relevance to atherosclerotic diseases, but also for diagnosis. Chromatographic methods are effective for indirectly measuring the oxidatively modified state of LDL or directly measuring the modified LDL. Indirect determination can be done by estimating the LDL subfraction, LDL particle size, oxidized amino acids in apolipoprotein B, lipid hydroperoxide or F(2)-isoprostane in LDL. Direct determination of the modified LDL in plasma can be done with chromatographic methods such as anion-exchange chromatography and size-exclusion chromatography. Other methods for estimating the modified state of LDL include electromigration methods such as agarose gel, polyacrylamide gradient gel and capillary electrophoresis. Recently, enzyme-linked immunosorbent assay methods of malondialdehyde (MDA)-LDL and autoantibodies against Ox-LDL have been developed to assess Ox-LDL in plasma. This review article summarizes the detection and assay methods of modified lipoproteins in plasma.