Can anti-oxidants prevent ischaemic heart disease?

Demographic Characteristics of Supplement Users in an Elderly Population

This study investigated the association of demographic characteristics with supplement use in 257 elderly participants of the Georgia Centenarian Study in their 60s (n = 89), 80s (n = 92), and 100s (n = 76). Of these elders, 44% used a specific vitamin or mineral supplement. Multivitamins/minerals (28%), vitamin C (13%), and vitamin E (7%) were the most common vitamins reported; whereas calcium (8%) and potassium (5%) were the most common minerals reported. Centenarians were as likely as those in their 60s and 80s to use a supplement. Females were more likely than males to report consuming any supplement and multivitamins/minerals; Whites were more likely than Blacks to report consuming any supplement, vitamin E, and vitamin C. Health care providers must be aware that even the oldest old are frequent users of supplements, but being male and of minority status may be a barrier to the use of nutritional supplements.

Oxysterols in heart failure

Oxysterols are biologically active molecules that result from the oxidation of cholesterol. Several oxysterols are found in macrophages and macrophage-derived 'foam cells' in atherosclerotic tissue. Lipophilic oxysterols penetrate cell membranes and, therefore, their concentrations can reach harmful levels in endothelial and smooth muscle cells located in close proximity to the atherosclerotic plaques or inflammatory zones. New findings suggest that the effects of oxysterols on cardiomyocytes can lead to cell hypertrophy and death. This may make oxysterols one of the major factors precipitating morbidity in atherosclerosis-induced cardiac diseases and inflammation-induced heart complications. The pathological actions of oxysterols on muscle cells were shown to depend on dysfunctional Ca(2+) signaling; however, the mechanisms of the effects remain to be elucidated. Understanding the effects of oxysterols could lead to therapies that modulate malfunction of cardiomyocytes. This review discusses the experimental findings and the relevance of oxysterols to heart failure, and suggests strategies for important future investigations.

Modulation of lipid metabolism by Centella asiatica in oxidative stress rats

A study was carried out to investigate the effects of Centella asiatica leaf on lipid metabolism of oxidative stress rats. The rats were fed 0.1% hydrogen peroxide (H(2)O(2)) with either 0.3% (w/w) C. asiatica extract, 5%C. asiatica powder (w/w), or 0.3% (w/w) alpha-tocopherol for 25 wk. Results of the study showed that C. asiatica powder significantly (P < 0.05) lowered serum low-density lipoprotein compared to that of control rats (rats fed H(2)O(2) only). At the end of the study C. asiatica-fed rats were also found to have significantly (P < 0.05) higher high-density lipoprotein and lower triglyceride level compared to rats fed only normal diet. However, cholesterol level of rats fed both C. asiatica extract and powder was found to be significantly (P < 0.05) higher compared to that of control rats. It was interesting to note that consumption of C. asiatica significantly decreased body and liver weights of the rats. Histological examinations revealed no obvious changes in all rats studied. Quantitative analysis of C. asiatica leaf revealed high concentration of total phenolic compounds, in particular, catechin, quercetin, and rutin.

Superoxide dismutase activity in adriamycin-induced cardiotoxicity in humans: a potential novel tool for risk stratification

BACKGROUND

Oxidative stress has been implicated in Adriamycin cardiotoxicity experimentally. We evaluated whether changes in systemic markers of antioxidant reserve occur and are associated with left ventricular (LV) dysfunction during Adriamycin use in humans.

METHODS AND RESULTS

We prospectively evaluated oncology patients eligible for Adriamycin chemotherapy. Blood samples for enzymatic (erythrocyte superoxide dismutase activity [SOD-U SOD/mg protein]) and nonenzymatic antioxidants (total radical trapping antioxidant potential [TRAP-U of Trolox/microL plasma]) were collected at baseline (B), intermediate (I), and final (F) cycles. LV ejection fraction (LVEF) was assessed by radionuclide ventriculography. Fifty-one patients (49 +/- 12 years, 90% female) underwent 5.9 +/- 0.9 chemotherapy cycles and received 301 +/- 52 mg/m 2 of Adriamycin. LVEF decreased from 61 +/- 6% (B) to 56 +/- 7% (F) ( P < .001), but only 6 (12%) patients developed significant LV systolic dysfunction (LVEF < 50%). SOD activity increased significantly during treatment (4.5 +/- 1.8 [B], 6.0 +/- 2.1 [I], 5.6 +/- 2.2 [F]; P < .01), whereas TRAP values were unchanged. Baseline SOD activity from patients who developed LV systolic dysfunction was significantly higher than from those who maintained normal LVEF (5.9 +/- 1.8 versus 4.3 +/- 1.7; P < .05). In multivariate analysis, baseline SOD levels remained independently associated with LV dysfunction ( P = .05).

CONCLUSION

Erythrocyte SOD activity increases after Adriamycin treatment and high baseline levels predicts Adriamycin-induced cardiotoxicity in humans.

Associations between plasma antioxidants and hypertension in a community-based sample of 415 Australians aged 60-64

It has been suggested that increased oxidative stress may be both a cause as well as a consequence of hypertension. In vivo oxidation of low-density lipoproteins by oxygen-free radicals may increase hypertension-related atherogenesis, and antioxidants may be beneficial in this regard. Previous findings concerning associations between serum measures of antioxidants and hypertension have however been inconsistent. Plasma levels of beta-carotene, Vitamin A, E, uric acid, homocysteine and total antioxidant capacity, as well as two markers of oxidative stress, malondialdehyde (MDA) and protein carbonyls, were measured in morning fasting blood samples provided by 415 Australians aged 60-64 years, selected randomly from the community. Participants also provided information on sociodemographic attributes, mental and physical health, and provided two measures of resting blood pressure, allowing a diagnosis of definite or borderline hypertension. Those with hypertension had lower levels of beta-carotene and higher levels of uric acid and MDA compared to normotensive participants. The last two of these associations persisted when the analyses controlled for lifestyle and health factors. The findings from this study offer limited support for the proposition that lower antioxidant status and higher oxidative stress are associated with hypertension, and suggest the need for longitudinal studies to examine causality and intervention studies to determine the benefit of antioxidants in this group.

Inhibitory effect of oolong tea on the oxidative state of low density lipoprotein (LDL)

In the present study, we investigated the anti-oxidant activity of oolong tea in an oxidation model using human low-density lipoprotein (LDL). Oolong tea suppressed the oxidation of LDL induced by 2-2'-azobis 4-methoxy-2,4-dimethyvaleronitrile (V70) in a dose-dependent manner, that is, it prolonged the lag time to 114.3%, 138% and 199.9% as compared with the control group at 0.5 microg/ml, 1.0 microg/ml, and 2.5 microg/ml, respectively. We also determined the scavenging effect of oolong tea on active oxygen radicals using the electron spin resonance (ESR) technique with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trapping agent. The intensity of the ESR signals for the DMPO-OOH adduct formed by the hypoxanthine/xanthine oxidase reaction system with DMPO decreased in the presence of oolong tea. The IC(50) of oolong tea was 19.9 microg/ml. These findings suggested that oolong tea has beneficial effects on health related to its anti-oxidative action.

Changes of oxidative stress in various tissues by long-term administration of vitamin E in hypercholesterolemic rats

BACKGROUND

Free radical-mediated oxidative stress has been implicated in the genesis and progression of atherosclerosis.

METHODS

The lipid peroxides and antioxidant status of various tissues were investigated in hypercholesterolemic rats and the effect of vitamin E supplementation on defense systems.

RESULTS

Cholesterol-feeding caused a significant increase in the lipid peroxide concentrations of plasma, erythrocytes, liver and brain. In addition, a significant decrease in glutathione (GSH) content, glutathione peroxidase (GSH-Px) and glutathione transferase (GSH-ST) activities were found in erythrocytes and liver but superoxide dismutase (SOD) activity remained unchanged in these tissues in comparison to the control group. Vitamin E supplementation to hypercholesterolemic rats induced a significantly decrease in lipid peroxide concentrations and a significant increase in the GSH content, GSH-Px and GSH-ST activities in erythrocytes and liver.

CONCLUSIONS

Long-term administration of vitamin E may play an important role in suppressing oxidative stress, and thus, may be useful for the prevention and/or early treatment of hypercholesterolemia.

The overexpression of copper-zinc superoxide dismutase protects NOS III from nitric oxide-mediated inhibition

Previously, we have demonstrated that increased superoxide generation plays a role in the nitric oxide (NO)-mediated inhibition of endothelial NO synthase (NOS III) in endothelial cells (ECs). In this study we demonstrate that the source of the superoxide is likely due to both NADPH oxidase and NOS III itself. Further, this increase appears to be linked to the activation of PKC, as PMA could mimic the increase and PKC inhibition ameliorate the increase. To further investigate this phenomenon we determined the effect of overexpression of copper-zinc superoxide dismutase (CuZn-SOD) and Manganese-SOD (Mn-SOD) on the inhibitory effects of NO. Using adenoviral infection we demonstrated that SOD activity was increased and superoxide levels decreased, in both CuZn-SOD and Mn-SOD overexpressing cells compared to cells infected with an adenovirus expressing bacterial beta-galactosidase protein. However, only the CuZn-SOD overexpression reduced the NO-mediated inhibition of NOS III. In addition, the level of NO-induced peroxynitrite generation and nitrated NOS III protein were reduced only in the CuZn-SOD overexpressing cells. In conclusion, our results indicate that superoxide and peroxynitrite are involved in the inhibition of NOS III by NO, and that the scavenging of superoxide may be necessary to prevent NOS III inhibition during treatments that involve inhaled NO or NO donors.

Antioxidant vitamins in the prevention of cardiovascular disease: a systematic review

Do antioxidant vitamins, in regular food or as food supplements, protect against myocardial infarction and stroke? In this systematic literature review on the effects of antioxidant vitamins in the primary prevention of cardiovascular disorders, studies with ischaemic heart disease, stroke or combined cardiovascular events as end-points have been included. Studies on the effects of antioxidant vitamins on intermediary end-points (such as blood lipids and blood pressure) and as secondary prevention in patients with manifest cardiovascular disease are reviewed in a conventional manner. In observational studies (case-control or cohort design), people with high intake of antioxidant vitamins by regular diet or as food supplements generally have a lower risk of myocardial infarction and stroke than people who are low-consumers of antioxidant vitamins. The associations in observation studies have been shown for carotene, ascorbic acid as well as tocopherol. In randomized controlled trials, however, antioxidant vitamins as food supplements have no beneficial effects in the primary prevention of myocardial infarction and stroke. Serious adverse events have been reported. After an initial enthusiasm for antioxidants in the secondary prevention of cardiovascular disease, recent reports from of several large randomized trials have failed to show any beneficial effects. Thus, the apparent beneficial results of high intake of antioxidant vitamins reported in observational studies have not been confirmed in large randomized trials. The discrepancy between different types of studies is probably explained by the fact that supplement use is a component in a cluster of healthy behaviour. Antioxidant vitamins as food supplements cannot be recommended in the primary or secondary prevention against cardiovascular disease.

Ascorbic acid metabolism in rats and guinea pigs after the administration of ethanol

Ascorbic acid metabolism was studied in guinea pigs and rats after the administration of ethanol and a high dose of ascorbic acid (AA). Male guinea pigs were maintained for 30 days as follows: (1) controls (1 mg AA/100 g body wt.); (2) ethanol (1 mg AA/100 g body wt. + 900 mg ethanol/100 g body wt); (3) ascorbic acid (25 mg AA/100 g body wt.); (4) ascorbic acid + ethanol (25 mg AA/100 g body wt. + 900 mg ethanol/100 g body wt.). Rats were also grouped into four groups as in the case of guinea pigs, but the dose of AA was 200 mg/100 g body weight. Rats adjusted to ethanol intoxication by enhancing the biosynthesis of ascorbate as evidenced by elevated activity of L-gulono lactone oxidase (GLO). Hence ascorbate levels were not lowered in rats after administration of alcohol. However, alcohol administration lowered tissue levels of ascorbate in guinea pigs. But the supplementation of ascorbate along with alcohol raised the tissue level of this vitamin. Guinea pigs responded to the ascorbate deficiency during alcohol administration by lowering the degradation of ascorbate, as seen by the lower activity of the degrading enzyme gulono lactone hydrolase. It is concluded that on the administration of alcohol, guinea pigs are dependent upon additional exogenous supplies of ascorbic acid, whereas rats are not.

Serum uric acid levels in cardiovascular diseases

OBJECTIVE

Comparison of the serum uric acid levels of healthy people (n=71) and patients with cardiovascular diseases (CVD) (n=62).

SUBJECTS AND METHODS

The patients included had either experienced acute myocardial infarction (AMI) (n=31), atherosclerosis (AT) (n=23) or ischaemia (n=8). The mean values (x+/-SD) of serum uric acid levels of the control group, the patients with CVD as a whole, and patients with AMI, AT and ischaemia were 4.15+/-0.45 mg%, 5.6+/-2.06 mg%, 5.96+/-2.60 mg%, 5.38+/-1.22 mg% and 4.94+/-1.40 mg%, respectively. A statistically higher level of serum uric acid was found in the controls compared to the CVD patients (P < 0.05).

CONCLUSION

The higher serum uric acid levels found in CVD patients suggests that any protective antioxidant effect which uric acid has is overwhelmed by other negative effects on pathogenesis.

Tetradecylthioacetic acid inhibits the oxidative modification of low density lipoprotein and 8-hydroxydeoxyguanosine formation in vitro

Oxidative modification of low-density lipoprotein (LDL) is thought to play a key role in the formation of foam cells and in initiation and progression of atherosclerotic plaque. The hypolipidemic 3-thia fatty acids contain a sulfur atom and might therefore possess reducing (antioxidant) properties. Consequently, the effects of 3-thia fatty acids on the susceptibility of LDL particles to undergo oxidative modification in vitro were studied. Tetradecylthioacetic acid (TTA), incorporated into the LDL particle and increased the lag time of copper ion induced LDL oxidation in a dose-dependent manner, 80 mumol/L TTA reduced the generation of lipid peroxides during copper ion induced LDL oxidation (for 2 hours) by 100%, 2,2'-azobis-(2,4-dimethylvaleronitrile) induced LDL oxidation by 64%, and 2,2'-azobis-(2-amidinopropane hydrochloride) induced LDL oxidation (for 6 hours) by 21%. The electrophoretic mobility of the oxidized LDL was reduced by TTA in both copper ion and azo-compounds initiated oxidation. This fatty acid analogue was effectively able to reduce in a dose dependent manner the formation of 8-hydroxydeoxyguanosine from 2-deoxyguanosine with ascorbic acid as the radical producer. TTA bound copper(II) ions and did not reduce copper(II) to copper(I). It failed to scavenge the 1,1-diphenyl-2-picrylhydrazyl radicals. The results suggest that the modification of LDL in the lipid and protein moieties can be significantly reduced by TTA. This acid may exert its antioxidant effect partially through metal ion binding and through free radical scavenging.

Vitamin E and exercise in the Northern Ireland population

Serum vitamin E, vitamin E/cholesterol and physical activity and fitness were examined in a representative cross section (n = 1600) of the Northern Ireland population as part of the Northern Ireland health and activity survey. Serum vitamin E levels were measured by high-performance liquid chromatography, cholesterol by an enzymatic method, physical activity profile was recorded by computer assisted interview and physical fitness was determined by estimation of VO2 max. The levels of serum vitamin E and vitamin E/cholesterol ratio in the Northern Irish population were similar or higher than in other populations with lower incidences of coronary heart disease. The assessment of activity showed that 75% of the population fell below recommended activity levels likely to confer a cardioprotective effect. A significant relationship (P = 0.01) was found in males between serum vitamin E levels and lifetime participation in physical activity. Otherwise no relationship was found between serum vitamin E or vitamin E/cholesterol ratio and physical activity or fitness in the population.

Lipid peroxidation: a review of causes, consequences, measurement and dietary influences

In this review the process of lipid peroxidation and the atherogenicity of peroxidied lipids are discussed. Recent findings with regard to the effect of selected dietary factors on susceptibility of lipids to oxidative stress and on antioxidant defences are analysed with particular reference to their potential use in the prevention and treatment of atherogenesis and, by extension, coronary heart disease. Laboratory methods of assessing antioxidant defences, lipid peroxidation and the effects of lipid peroxidation are also reviewed and discussed with particular reference to their ability to assess in vivo oxidative stress and lipid peroxidation status. A range of oxidative stress indices are presented and their limitations discussed, but the main focus is on the most commonly used laboratory test for lipid peroxidation, the thiobarbituric acid reacting substances (TBARS) test. Finally, the influence of selected dietary factors on measured peroxidation status is discussed, with particular reference to the antioxidant vitamins C (ascorbic acid) and E (alpha tocopherol) and the type of fatty acids (mono- and poly-unsaturated) in the diet.

Lipids, lipoproteins, antioxidants and glomerular and tubular dysfunction in type 1 diabetes

We aimed to examine the relationship of serum lipids, lipoproteins, apolipoproteins and antioxidants with renal dysfunction as measured by urinary excretion of albumin and of retinol binding protein (RBP) in insulin-dependent diabetes mellitus (IDDM). We studied 121 patients with IDDM. Glomerular function was assessed as the urinary albumin/creatinine ratio (UA/UC), and tubular function as the urinary retinol-binding protein/creatinine ratio (UR/UC), both measured in three early morning spot urine samples. The mean (range) UA/UC was 1.95 mg/mmol (0.3-476.5) and UR/UC was 17.5 micrograms/mmol (1.0-1853.8). 17% of the patients had a UA/UC > 3 mg/mmol and 33% had a UR/UC > 20 micrograms/mmol. Significant positive correlations were observed between both UA/UC and UR/UC and the following: serum total cholesterol (P < 0.005); triglycerides (P < 0.001); apolipoproteins A-I (P < 0.05), A-II (P < 0.02) and B (P < 0.002); glycated haemoglobin (P < 0.002). No significant associations were found with serum vitamin E, beta-carotene or total antioxidant activity. In multiple regression, only UA/UC was independently associated with serum apo B and cholesterol concentrations. In conclusion, in IDDM glomerular dysfunction, as measured by UA/UC, is associated with elevated serum cholesterol, triglycerides, apo B, apo A-I and apo A-II, but not with HDL cholesterol or antioxidant status. Tubular dysfunction tends to occur with increasing albuminuria, but it is not independently associated with serum lipid, lipoprotein, apolipoprotein or antioxidant levels.

Serum levels of vitamin E in relation to cardiovascular diseases

Serum vitamin E levels in healthy people (n = 71) and patients with cardiovascular diseases (n = 62) were determined. The cases of cardiovascular disease comprised patients with acute myocardial infarction (AMI) (n = 31), atherosclerosis (AT) (n = 23) and myocardial ischaemia (MI) (n = 8). The mean (+/- SD) serum vitamin E levels of the control group and the group with cardiovascular disease were 1.12 +/- 0.27 mg% and 0.98 +/- 0.41 mg%, respectively. Patients with AMI, AT and MI had corresponding levels of 0.97 +/- 0.48 mg%, 1.00 +/- 0.39 mg% and 1.01 +/- 0.44 mg%, respectively. Overall serum vitamin E levels were lower in the group with cardiovascular disease than in the control group. Patients and the control group are also discussed with respect to a number of potentially confounding parameters such as age, sex, smoking status, quetelet index (kg/m2), alcohol consumption, dietary intake and serum lipids.

Simple determination of retinol, alpha-tocopherol and carotenoids (lutein, all-trans-lycopene, alpha- and beta-carotenes) in human plasma by isocratic liquid chromatography

Retinol, alpha-tocopherol, lutein, all-trans-lycopene, and alpha- and beta-carotenes can be simultaneously determined in human plasma by reversed-phase liquid chromatography with a programmable and variable UV wavelength detector. Plasma (200 microliters) is deproteinized with 200 microliters of ethanol containing retinyl acetate, as internal standard, then extracted with 1.0 ml of n-hexane-2,6-di-tert.-butyl-p-cresol (BHT). The organic layer is removed and evaporated and the residue is dissolved in 100 microliters of a mixture of acetonitrile-tetrahydrofuran-methanol (68:22:7, v/v/v). Aliquots (15 microliters) are injected onto a 250 x 4.6 mm I.D. column of Nucleosil 100-5 C18 with a pre-column of Lichrosorb RP-18, 7 microns, 15 x 3.2 mm I.D. A mobile phase of acetonitrile-tetrahydrofuran-methanol (68:22:7, v/v/v), adjusted to 100 (v/v) with 1% ammonium acetate, at a flow-rate of 1.5 ml/min is used. Usual run time is 15 min. Retinol and retinyl acetate are monitored at 325 nm, tocopherol at 290 nm, lycopene at 470 nm, lutein and alpha- and beta-carotenes at 450 nm. The intra-batch coefficients of variation (C.V.) were 2.5, 2.2, 2.4, 5.8, 5.1 and 4.7% for retinol, alpha-tocopherol, lutein, trans-lycopene, alpha- and beta-carotenes, respectively. The inter-batch C.V.s of experiments performed on 30 different days over 12 weeks were 5.7, 3.9, 4.5, 10.9, 11.3 and 10.5%, respectively.