Ascorbate and urate are the strongest determinants of plasma antioxidative capacity and serum lipid resistance to oxidation in Finnish men

High density lipoprotein heterogeneity & function among Indians with coronary artery disease

Background & objectives

Impaired high density lipoprotein (HDL) functionality has been shown to be associated with cardiovascular disease risk. The study was aimed to identify the alterations in HDL function [antioxidative activity (AOA)] and subfraction distribution between acute coronary syndrome (ACS) and stable coronary artery disease (SCAD) individuals and analysing the accuracy of HDL parameters to discriminate between the groups.

Methods

HDL subfraction distribution analysis was performed in 200 coronary artery disease patients (ACS and SCAD) and 60 control individuals using dextran sulphate, heparin and manganese chloride precipitation method. In terms of HDL function, AOA was evaluated by dihydrorhodamine-based fluorescent cell-free assay and paraoxonase (PON1) enzyme paraoxonase and arylesterase activity.

Results

We found that higher AOA [odds ratio (95% confidence interval {CI})]: 0.09 (0.02-0.44), P<0.01 for SCAD; 0.008 (0.001-0.07), P<0.001 for ACS and higher PON1 activity [0.22 (0.8-0.59), P<0.01 for SCAD; 0.16 (0.06-0.4), P<0.001 for ACS] were associated with a lower odds of developing coronary artery disease (CAD). AOA of apoB-depleted serum was significantly correlated with HDL2-C/HDL3-C (HDL-cholesterol) ratio in controls (r=-0.31, P=0.01) and ACS (r=-0.18, P=0.04). It was observed that AOA and HDL subfraction distribution together could discriminate between the two groups of CAD with an accuracy of 72.8 per cent (P=0.004).

Interpretation & conclusions

Impaired AOA and altered subfraction distribution of HDL may be responsible for its diminished anti-athero protective activity and can discriminate between the two groups of CAD individuals.

Host-Derived Cytotoxic Agents in Chronic Inflammation and Disease Progression

At inflammatory sites, cytotoxic agents are released and generated from invading immune cells and damaged tissue cells. The further fate of the inflammation highly depends on the presence of antagonizing principles that are able to inactivate these host-derived cytotoxic agents. As long as the affected tissues are well equipped with ready-to-use protective mechanisms, no damage by cytotoxic agents occurs and resolution of inflammation is initiated. However, long-lasting and severe immune responses can be associated with the decline, exhaustion, or inactivation of selected antagonizing principles. Hence, cytotoxic agents are only partially inactivated and contribute to damage of yet-unperturbed cells. Consequently, a chronic inflammatory process results. In this vicious circle of permanent cell destruction, not only novel cytotoxic elements but also novel alarmins and antigens are liberated from affected cells. In severe cases, very low protection leads to organ failure, sepsis, and septic shock. In this review, the major classes of host-derived cytotoxic agents (reactive species, oxidized heme proteins and free heme, transition metal ions, serine proteases, matrix metalloproteases, and pro-inflammatory peptides), their corresponding protective principles, and resulting implications on the pathogenesis of diseases are highlighted.

Activity of CdTe Quantum-Dot-Tagged Superoxide Dismutase and Its Analysis in Capillary Electrophoresis

Quantum dots (QDs) have a broad range of applications in cell biolabeling, cancer treatment, metastasis imaging, and therapeutic drug monitoring. Despite their wide use, relatively little is known about their influence on other molecules. Interactions between QDs and proteins can influence the properties of both nanoparticles and proteins. The effect of mercaptosuccinic acid-capped CdTe QDs on intercellular copper–zinc superoxide dismutase (SOD1)—one of the main enzymatic antioxidants—was investigated. Incubation of SOD1 with QDs caused an increase in SOD1 activity, unlike in the case of CdCl₂, which inhibited SOD1. Moreover, this effect on SOD1 increased with the size and potential of QDs, although the effect became clearly visible in higher concentrations of QDs. The intensity of QD-SOD1 fluorescence, analyzed with the use of capillary electrophoresis with laser-induced fluorescence detection, was dependent on SOD1 concentration. In the case of green QDs, the fluorescence signal decreased with increasing SOD1 concentration. In contrast, the signal strength for Y-QD complexes was not dependent on SOD1 dilutions. The migration time of QDs and their complexes with SOD1 varied depending on the type of QD used. The migration time of G-QD complexes with SOD1 differed slightly. However, in the case of Y-QD complexes with SOD1, the differences in the migration time were not dependent on SOD concentration. This research shows that QDs interact with SOD1 and the influence of QDs on SOD activity is size-dependent. With this knowledge, one might be able to control the activation/inhibition of specific enzymes, such as SOD1.

Rule of UA on Cardiac Myocytes Uric Acid Differently Influence the Oxidative Damage Induced by Acute Exposure of High Level of Glucose in Chicken Cardiac Myocytes

Background: Uric acid (UA) is a potent scavenger of oxidants in mammalian and avian species. In humans, hyperglycemia with simultaneous hyperuricemia may exert additional damage to the cardiovascular system. Chickens naturally have hyperglycemia (10.1–11.0 mmol/L) and hyperuricemia (100–900 μmol/L), which makes them an interesting model.

Methods: The aim of this study was to investigate the effects of UA on the oxidative damage induced by acute exposure of high level of glucose in chicken cardiac myocytes.

Results: Cell viability and the concentrations of thiobarbituric acid reactive substance (TBARS) were decreased by glucose treatment in a dose- and time-dependent manner. After acute exposure to high level of glucose (300 mM), a moderate level of UA (300 μM) increased cell viability and reduced TBARS and glutathione (GSH) content. Compared to the control or to independent high glucose (300 mM) or UA (1,200 μM) treatment, the concurrent treatment of high glucose and high UA significantly increased the TBARS, protein carbonyl contents, and ROS concentration, whereas it decreased the cell viability, superoxide dismutase (SOD) activity, and GSH content. In the presence of high glucose and UA, the nucleic protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2) was decreased and the mRNA levels of the genes cat, sod1, sod2, gss, and gclc were downregulated.

Conclusion: In conclusion, acute exposure of high level of glucose induced oxidative damage in the cardiac myocytes of chicken. The present result suggests that an adequate level of uric acid is helpful in alleviating the acute oxidative damage that is induced by high glucose, whereas the inhibition of the Nrf2 pathway by a high level of uric acid may render the cardiac myocytes more vulnerable to suffering from oxidative damage.

The Dual Role of Myeloperoxidase in Immune Response

The heme protein myeloperoxidase (MPO) is a major constituent of neutrophils. As a key mediator of the innate immune system, neutrophils are rapidly recruited to inflammatory sites, where they recognize, phagocytose, and inactivate foreign microorganisms. In the newly formed phagosomes, MPO is involved in the creation and maintenance of an alkaline milieu, which is optimal in combatting microbes. Myeloperoxidase is also a key component in neutrophil extracellular traps. These helpful properties are contrasted by the release of MPO and other neutrophil constituents from necrotic cells or as a result of frustrated phagocytosis. Although MPO is inactivated by the plasma protein ceruloplasmin, it can interact with negatively charged components of serum and the extracellular matrix. In cardiovascular diseases and many other disease scenarios, active MPO and MPO-modified targets are present in atherosclerotic lesions and other disease-specific locations. This implies an involvement of neutrophils, MPO, and other neutrophil products in pathogenesis mechanisms. This review critically reflects on the beneficial and harmful functions of MPO against the background of immune response.

An association of smoking with serum urate and gout: A health paradox

BACKGROUND

The potential effect of cigarette smoking on levels of serum urate and risk of gout has been considered by a large number of studies, either as the primary variable of interest or as a covariate.

METHODS

Here we systematically review the published evidence relating to the relationship of smoking with serum urate, hyperuricaemia, and gout.

RESULTS

Many studies have reported that smoking reduces serum urate, however, the evidence has not been conclusive with other studies pointing to the opposite or no effect. It has also been suggested that smoking reduces the risk of gout, although there is some evidence to contradict this finding.

CONCLUSION

A consensus has yet to be reached as to the effect of smoking on serum urate levels and the risk of gout.

Antioxidative activity of high-density lipoprotein (HDL): Mechanistic insights into potential clinical benefit

Uptake of low-density lipoprotein (LDL) particles by macrophages represents a key step in the development of atherosclerotic plaques, leading to the foam cell formation. Chemical modification of LDL is however necessary to induce this process. Proatherogenic LDL modifications include aggregation, enzymatic digestion and oxidation. LDL oxidation by one-electron (free radicals) and two-electron oxidants dramatically increases LDL affinity to macrophage scavenger receptors, leading to rapid LDL uptake and fatty streak formation. Circulating high-density lipoprotein (HDL) particles, primarily small, dense, protein-rich HDL3, provide potent protection of LDL from oxidative damage by free radicals, resulting in the inhibition of the generation of pro-inflammatory oxidized lipids. HDL-mediated inactivation of lipid hydroperoxides involves their initial transfer from LDL to HDL and subsequent reduction to inactive hydroxides by redox-active Met residues of apolipoprotein A-I. Several HDL-associated enzymes are present at elevated concentrations in HDL3 relative to large, light HDL2 and can be involved in the inactivation of short-chain oxidized phospholipids. Therefore, HDL represents a multimolecular complex capable of acquiring and inactivating proatherogenic lipids. Antioxidative function of HDL can be impaired in several metabolic and inflammatory diseases. Structural and compositional anomalies in the HDL proteome and lipidome underlie such functional deficiency. Concomitant normalization of the metabolism, circulating levels, composition and biological activities of HDL particles, primarily those of small, dense HDL3, can constitute future therapeutic target.

Advanced glycation end-products: modifiable environmental factors profoundly mediate insulin resistance

Advanced glycation end-products are toxic by-products of metabolism and are also acquired from high-temperature processed foods. They promote oxidative damage to proteins, lipids and nucleotides. Aging and chronic diseases are strongly associated with markers for oxidative stress, especially advanced glycation end-products, and resistance to peripheral insulin-mediated glucose uptake. Modifiable environmental factors including high levels of refined and simple carbohydrate diets, hypercaloric diets and sedentary lifestyles drive endogenous formation of advanced glycation end-products via accumulation of highly reactive glycolysis intermediates and activation of the polyol/aldose reductase pathway producing high intracellular fructose. High advanced glycation end-products overwhelm innate defenses of enzymes and receptor-mediated endocytosis and promote cell damage via the pro-inflammatory and pro-oxidant receptor for advanced glycation end-products. Oxidative stress disturbs cell signal transduction, especially insulin-mediated metabolic responses. Here we review emerging evidence that restriction of dietary advanced glycation end-products significantly reduces total systemic load and insulin resistance in animals and humans in diabetes, polycystic ovary syndrome, healthy populations and dementia. Of clinical importance, this insulin sensitizing effect is independent of physical activity, caloric intake and adiposity level.

Epicardial fat tissue thickness is correlated with diminished levels of co-enzyme Q10, a major antioxidant molecule among hemodialysis patients

OBJECTIVES

Accelerated atherosclerosis is the major cause of mortality in patients on chronic maintenance hemodialysis (HD). Epicardial fat tissue (EFT) is a new risk factor in cardiovascular disease (CVD). The aim of this study was to evaluate the relation between plasma coenzyme Q10 levels (Co-Q10) which is a potent physiologic antioxidant and EFT thickness in HD patients.

DESIGN AND METHODS

Seventy one chronic HD patients and 65 age and sex matched healthy individuals were included in the study. Plasma Co-Q10 levels were performed by high-performance liquid chromatography (HPLC) measurements. EFT was measured by transthoracic echocardiograpy (TTE) performed with a VIVID 7 instrument.

RESULTS

Plasma Co-Q10 levels (1.36±0.43 vs 2.53±0.55, p<0.001) were significantly lower in HD patients compared to controls. EFT was significantly increased in HD patients compared to healthy controls (6.53±1.01 vs. 5.79±1.06 mm respectively, p<0.001). Correlation analysis showed that plasma Co-Q10 levels were inversely correlated with EFT (r=-0.263, p<0.05). Multiple linear regression analysis was used to define independent determinants of EFT in HD patients. According to linear regression analysis, age, BMI, total cholesterol and Co-Q10 levels were found to be independent predictors of EFT (adjusted r(2)=0.38, p<0.001).

CONCLUSION

This study demonstrated that EFT thickness was significantly higher among HD patients compared to healthy controls. In addition; this study was the first to demonstrate an inverse correlation between EFT thickness and Co-Q10 levels in this patient population.

Cinacalcet may improve oxidative DNA damage in maintenance hemodialysis patients: an observational study

BACKGROUND

Oxidative stress is accepted as a non-classical cardiovascular risk factor in patients on maintenance hemodialysis (HD). The aim of this study was to evaluate the impact of cinacalcet on oxidative stress biomarkers, oxidative DNA damage (8-hydroxy-2'-deoxyguanosine/deoxyguanosine), endothelial function (FMD %) and carotid artery intima-media thickness (CIMT) in HD patients.

METHODS

Forty-two chronic HD patients with secondary hyperparathyroidism undergoing 60 mg/day cinacalcet treatment with a follow-up of 6 months and 38 age- and sex-matched healthy individuals were included in this prospective study. Plasma malondialdehyde (MDA) levels and 8-hydroxy-2'-deoxyguanosine/deoxyguanosine ratio (8-OHdG/dG) were determined as oxidative stress markers. Superoxide dismutase (SOD), paraoxonase (PON), catalase (CAT), carbonic anhydrase (CAN) and glutathione peroxidase (GPx) activities were measured as antioxidants. FMD % and CIMT were assessed by ultrasonography.

RESULTS

MDA levels were decreased; SOD, PON, CAT, CAN and GPx activities were increased after 6 months of cinacalcet treatment in HD patients. Although CIMT remained stabile, there was a significant improvement in FMD % as well as a notable reduction trend in 8-OHdG/dG ratio after 6 months of treatment.

CONCLUSION

Our data have demonstrated that cinacalcet improves oxidative stress, genomic damage, endothelial function and increases antioxidant protection in HD patients after 6 months of treatment.

Seasonal differences in total antioxidant capacity intake from foods consumed by a Japanese population

BACKGROUND/OBJECTIVES

This cross-sectional study aimed to estimate total antioxidant capacity (TAC) intake from food and beverages in a Japanese population from 7-day seasonal dietary records.

SUBJECTS/METHODS

The 7-day weighed dietary records of 390 subjects over four seasons between 1996 and 1998 were used. The TAC values (μmol trolox equivalents (μmol TE)/g) of various foods and beverages were defined, as reported in previous studies for weighed dietary records, using several different methods. TAC values of foods were estimated in 242 food and beverage items: 86.5% of vegetables, 99.1% of fruits, 71.5% of potatoes, 96.7% of beans, and 100% of chocolates. Differences in TAC intake per day and intake (g) per day among seasons in each of the food and beverage group were compared using a general linear model for repeated measures. The TAC intake/day were calculated for each food and beverage item in the four seasons.

RESULTS

TAC intake/day (μmol TE/day) varied from 10 189 (summer) to 12 292 (winter). TAC intake/day from fruits (2696) and potatoes (395) was highest in autumn, from vegetables (2827) it was highest in summer and from beans (4151) and tea (2331) it was highest in winter.

CONCLUSIONS

The dietary habits of the studied Japanese population showed the highest antioxidant capacity in winter and the lowest in summer.

The association between serum uric acid and residual β -cell function in type 2 diabetes

The aim of this study was to investigate the relationship of serum uric acid (sUA) with residual β -cell function in type 2 diabetes. Oral glucose tolerance tests (OGTT) were performed on 1021 type 2 diabetes patients. The ratio of area under curve of insulin to glucose during 0 to 30 min and 0 to 120 min of the OGTT was calculated as indices of insulin secretion function. The products of insulin secretion indices multiplied by Matsuda insulin sensitivity index were used as disposition indices. After correlation and multiple linear regression analysis, sUA was significantly associated with insulin secretion and disposition indices in male, female, and total groups adjusted for confounding factors (including metabolic indicators like sex, age, course of the disease, blood glucose, blood pressure, serum lipids, and so on). Superficially steeper time-dependent decline of insulin secretion function was found in patients with sUA above the median than those below it. In conclusion, our results suggest an independent positive association between sUA and residual β -cell function in type 2 diabetes. Patients with higher sUA have greater insulin secretion ability than those with lower sUA at the early stage of disease, but their residual β -cell function seems to decay more rapidly.

Decreased serum selenium levels are correlated with diminished coronary flow reserve among hemodialysis patients

Cardiovascular diseases are the main reason of high mortality among hemodialysis patients. Decreased serum selenium levels may have a role in accelerated atherosclerosis in this patient group. The hypothesis of this study was to show a correlation between decreased serum selenium levels and coronary flow reserve as an indicator of endothelial dysfunction and atherosclerosis in HD patients. Seventy-one chronic hemodialysis patients and age 65 and sex-matched healthy controls were included in the study. Plasma selenium levels were measured by spectrophotometry, and coronary flow reserve was assessed by transthoracic Doppler echocardiography. Serum selenium levels (34.16 ± 6.15 ng/ml vs. 52.4 ± 5.51 ng/ml, P < 0.001) and coronary flow reserve values (1.73 ± 0.11 vs. 2.32 ± 0.28, P < 0.001) were significantly lower in hemodialysis patients compared with controls, respectively. There was a significant positive correlation between coronary flow reserve and serum levels of selenium (r = 0.676, P < 0.001). A linear regression analysis showed that serum levels of selenium were independently and positively correlated with coronary flow reserve (regression coefficient = 0.650, P < 0.05). This study was the first to show a positive and independent correlation between decreased selenium levels and diminished coronary flow reserve as an indicator of endothelial dysfunction and atherosclerosis in hemodialysis patients. Our data suggest that decreased serum selenium levels may facilitate the development of endothelial dysfunction and disruption of coronary flow reserve which occur before the development of overt atherosclerosis.

The effect of the systemic inflammatory response, as provoked by elective orthopaedic surgery, on serum uric acid in patients without gout: a prospective study

OBJECTIVE

Acute gout is associated with a decrease in serum uric acid (SUA) that is considered to be in response to acute inflammation but it may be a feature of gout itself. We, therefore, aimed to investigate the effect of the acute systemic inflammatory response (SIR) on SUA concentrations in subjects without gout.

METHODS

SUA and urinary excretion of uric acid (UA) (expressed as fractional excretion of UA; FEua%) were measured in 30 patients before and 48 h after elective knee or hip surgery. The SIR was assessed by measuring serum CRP and urine microalbumin excretion [expressed as the albumin-creatinine ratio (ACR)] before and after surgery in the same patients.

RESULTS

The mean (s.d.) serum CRP increased following surgery [5.0 (5.5) vs 116.0 (81.2) mg/l; P < 0.0001) as did urine ACR [0.85 (1.03) vs 2.10 (2.60) mg/mmol; P = 0.004]. SUA decreased following surgery [312 (64) vs 282 (82) µmol/l; P = 0.0033] but FEua% was unchanged [6.4 (2.3) vs 7.3 (3.3)%; P = 0.1726].

CONCLUSION

The SIR is associated with a decrease in SUA concentrations in normouricaemic patients without gout. The decrease in SUA concentrations is not due to increased urinary excretion of UA. This study supports the notion that the decrease in SUA during acute gout is due to the associated SIR rather than gout per se.

Serum coenzyme Q10 levels are associated with coronary flow reserve in hemodialysis patients

Accelerated atherosclerosis is the major cause of mortality in patients on chronic hemodialysis (HD). The aim of this study was to evaluate the relation between coenzyme Q10 (CoQ10) levels and coronary flow reserve (CFR) in HD patients as an indicator of atherosclerosis. Seventy-one chronic HD patients and 65 age- and sex-matched healthy individuals were included in the study. Plasma CoQ10 levels were performed by high-performance liquid chromatography measurements. CFR was assessed by transthoracic Doppler echocardiography. Serum CoQ10 levels (1.36 ± 0.43 vs. 2.53 ± 0.55, P < 0.001) and CFR values (1.73 ± 0.11 vs. 2.32 ± 0.28, P < 0.001) were significantly lower in HD patients compared with controls. There was a significant positive correlation between CFR and serum levels of CoQ10 (r = 0.669, P < 0.001). A linear regression analysis showed that serum levels of CoQ10 were still significantly and positively correlated with CFR (regression coefficient = 0.235, P < 0.001). Our data have demonstrated that HD patients exhibit decreased plasma CoQ10 levels and CFR values. The study also showed for the first time that serum CoQ10 levels independently predict CFR in HD patients.

NMR protocol for determination of oxidation susceptibility of serum lipids and application of the protocol to a chocolate study

A protocol for determination of oxidation susceptibility of serum lipids based on proton nuclear magnetic resonance ((1)H NMR) spectroscopy is presented and compared to the commonly used spectrophotometric method. Even though there are methodological differences between these two methods, the NMR-based oxidation susceptibility correlates well (r(2) = 0.73) with the lag time determined spectrophotometrically. In addition to the oxidizability of serum lipids, the NMR method provides also information about the lipid profile. The NMR oxidation assay was applied to the chocolate study including fasting serum samples (n = 45) from subjects who had consumed white (WC), dark (DC) or high-polyphenol chocolate (HPC) daily for 3 weeks. The oxidation susceptibility of serum lipids decreased in the HPC group, and there was a significant difference between the WC and HPC groups (P = 0.031). According to the random forest analysis, the consumption of the HPC chocolate induced changes to the amounts of HDL, phosphatidylcholine, sphingomyelin, and nervonic, docosahexaenoic and myristic acids. Furthermore, arachidonic, docosahexaenoic, docosapentaenoic and palmitic acids, gamma-glutamyl transferase, hemoglobin, HDL, phosphatidylcholine and choline containing phospholipids explained about 60% of the oxidation susceptibility values. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11306-011-0323-2) contains supplementary material, which is available to authorized users.

Fast repair of protein radicals by urate

The repair of tryptophan and tyrosine radicals in proteins by urate was studied by pulse radiolysis. In chymotrypsin, urate repairs tryptophan radicals efficiently with a rate constant of 2.7 × 10(8)M(-1)s(-1), ca. 14 times higher than the rate constant derived for N-acetyltryptophan amide, 1.9 × 10(7)M(-1)s(-1). In contrast, no repair of tryptophan radicals was observed in pepsin, which indicates a rate constant smaller than 6 × 10(7)M(-1)s(-1). Urate repairs tyrosine radicals in pepsin with a rate constant of 3 × 10(8)M(-1)s(-1)-ca. 12 times smaller than the rate constant reported for free tyrosine-but not in chymotrypsin, which implies an upper limit of 1 × 10(6)M(-1)s(-1) for the corresponding rate constant. Intra- and intermolecular electron transfer from tyrosine residues to tryptophan radicals is observed in both proteins, however, to different extents and with different rate constants. Urate inhibits electron transfer in chymotrypsin but not in pepsin. Our results suggest that urate repairs the first step on the long path to protein modification and prevents damage in vivo. It may prove to be a very important repair agent in tissue compartments where its concentration is higher than that of ascorbate. The product of such repair, the urate radical, can be reduced by ascorbate. Loss of ascorbate is then expected to be the net result, whereas urate is conserved.

The relationship between severity of calcific aortic stenosis and serum uric acid levels

Serum uric acid (SUA) level is a marker of endothelial dysfunction and oxidative stress. Consecutive patients (n = 64) with normal coronary angiography who demonstrated calcific aortic stenosis (AS) by transthoracic echocardiography were included in the study. The patients were categorized into 3 groups: 23 mild AS (12 males), 21 moderate AS (10 males), and 20 severe AS cases (10 males). Fasting SUA level was significantly higher in the severe AS group than in the moderate and mild AS groups (severe AS, 6.3 ± 1.6; moderate AS, 4.9 ± 1.3; mild AS; 4.6 ± 1.4 mg/dL; P < .001, respectively). There was a positive correlation between SUA level and maximum as well as mean aortic gradient (r = .521, P < .001 and r = .526, P < .001, respectively). There was a negative correlation between SUA level and aortic valve area (r = -.447, P < .001). Levels of SUA were increased in calcific AS cases. In addition, there was a positive correlation between severity of calcific AS and SUA levels.

Relationship between uric acid and metabolic syndrome according to menopausal status

OBJECTIVE

Uric acid, the levels of which have been shown to increase after menopause, has been associated with metabolic syndrome. The prevalence of metabolic syndrome has also been determined to increase after menopause. Therefore, we surmised that menopausal status-specific analyses for the characterisation of the relationship between uric acid and the metabolic syndrome were warranted.

METHODS

We included 1644 patients: 1018 premenopausal women and 626 postmenopausal women, all of whom participated in annual health examinations at Anam Hospital in Seoul, Korea, from January 2008 through December 2008.

RESULTS

On the multivariate logistic regression analysis, uric acid was identified as an independent risk factor for metabolic syndrome in both premenopausal and postmenopausal women. Uric acid levels had different relationships with blood pressure based on menopausal status, however, no such relationships with fasting glucose or age were found.

CONCLUSIONS

Increased uric acid levels were associated with increased risk for metabolic syndrome in both premenopausal and postmenopausal women. In studies regarding uric acid and metabolic syndrome in women, the effects of menopausal status should be considered.

Evaluation of urinary biomarkers of oxidative/nitrosative stress in adolescents and adults with Down syndrome

Urinary biomarkers of oxidative stress have been little studied in adults with Down syndrome (DS), usually no more than two biomarkers have been measured in the population studied and controversial results are reported in literature. Thus, we aimed to assess a set of oxidative and nitrosative stress biomarkers in urine samples of adolescents and adults with DS, with and without hypothyroidism, which comprise: 8-hydroxy-2'-deoxyguanosine (8-OHdG), isoprostane 15-F(2t)-IsoP, thiobarbituric acid-reacting substances (TBARS), advanced glycation end products (AGEs), dityrosine (diTyr), hydrogen peroxide (H(2)O(2)) and nitrite/nitrate (NOx). Fluorimetric and spectrophotometric assays were performed in DS (n=78), some of them taking levothyroxine for hypothyroidism (n=24), and in their healthy age-matched controls (n=65). We found that levels of AGEs, diTyr, H(2)O(2) and NOx are increased in DS patients in any or in all age groups, whereas Cr levels were lower in DS than in controls in all age groups. Besides, correlations with age in DS were positive for diTyr and negative for Cr, TBARS, 15-F(2t)-IsoP and NOx. We also found lower levels of Cr from 15 to 19years, higher levels of TBARS and AGEs from 20 to 40years and higher levels of diTyr from 15 to 40years in DS patients receiving levothyroxine than in DS without hypothyroidism diagnosed. We conclude that AGEs, diTyr, H(2)O(2) and NOx could be used as oxidative stress biomarkers in DS in contrast to 8-OHdG, 15-F(2t)-IsoP and TBARS, at least with the methods used. However, renal impairment could occur in DS and Cr adjustment may bias the results, particularly in hypothyroid patients.

Influence of physical activity intensity and aerobic fitness on the anthropometric index and serum uric acid concentration in people with obesity

BACKGROUND AND OBJECTIVE

Physical activity (PA) is considered an important approach to prevent and treat obesity and hyperuricemia. The purpose of the present study was to examine the influence of PA intensity and aerobic fitness on anthropometric indices and serum uric acid in obese individuals.

METHODS

PA was examined using a single-axial accelerometer and aerobic fitness was assessed by electric cycle ergometry in obese middle-aged men (n=71, 47.2 ± 4.4 years). PA was defined as light (<3 metabolic equivalents [METs]), moderate (3.0-6.0 METs) or vigorous (>6.0 METs) intensity from the corresponding METs multiplied by time spent at the corresponding intensity levels. Serum uric acid was measured by the uricase peroxidase method.

RESULTS

The association between aerobic fitness index (lactate threshold) and serum uric acid did not reach statistical significance after adjustment for potential confounding factors (age, body mass index [BMI], and alcohol consumption) (β=-0.110, p=0.138). Light intensity PA was inversely associated with BMI and waist circumference, even after adjustment for age and alcohol consumption (BMI: β=-0.543, p=0.023; waist circumference: β=-1.333, p=0.016). Moderate intensity PA, but not light or vigorous intensity PA, was inversely correlated with the uric acid level and this remained significant after adjustment for age, BMI, and alcohol consumption (β=-0.222, p=0.036).

CONCLUSION

Our results suggest that light intensity PA may have an important role in weight control while moderate intensity PA may be associated with the lower uric acid concentrations in obese individuals.

Oxidative stress in COPD and its measurement through exhaled breath condensate

Oxidative stress and airway inflammation together form a vicious cycle, which is responsible for the disease progression in chronic pulmonary obstructive disease (COPD). The damaging effects of oxidative stress accumulate over the years, causing increased bronchial hyperresponsiveness and inflammation and destruction of airway epithelial cells and impairing the functions of antiproteases and surfactant. Although the lung expresses a number of antioxidants, cigarette smoking and recurrent infections associated with this disease overwhelm this protective mechanism. Studies of antioxidants in COPD have yielded conflicting results, probably due to the compartmentalization of these mediators, and because of the fact that the lung is a difficult organ to sample. Chronic exposure to oxidants upregulates the production of antioxidants, which become depleted during acute exacerbations. Future studies of the pathogenesis of COPD require a noninvasive yet accurate sampling procedure, of which exhaled breath condensate (EBC) is a good candidate. EBC samples the epithelial lining fluid, which contains the local oxidative stress markers in the lung. Oxidative stress markers such as hydrogen ions, hydrogen peroxide, 8-isoprostanes, thiobarbituric acid reactive products, nitrosothiols, and nitrite/nitrate have been identified in EBC of COPD patients, whereas many other markers of the oxidative-antioxidative balance have yet to be investigated.

Lycopene, lutein and beta-carotene as determinants of LDL conjugated dienes in serum

Oxidative modification of low-density lipoprotein (LDL) in the vascular endothelium is considered to be important in the development of early atherosclerosis. The aim of this study was to investigate the main determinants of serum LDL conjugated dienes in women (n=124) and men (n=225). We focused on the influence of fat-soluble vitamins and carotenoids on the concentration of conjugated dienes in LDL. In multivariate linear regression models, including age, body mass index, diastolic blood pressure, symptomatic ischaemic heart disease (IHD) or IHD history, statin medication, leukocytes and serum triglycerides as covariates, plasma lycopene (standardized beta=-0.33; P=0.002) and lutein (standardized beta=-0.22; P=0.027) concentrations were the strongest determinants of serum LDL conjugated dienes in women, whereas plasma beta-carotene (standardized beta=-0.23; P=0.002) was the most important factor in men. Furthermore, statin medication, diastolic blood pressure, age and serum triglycerides were significant determinants of LDL conjugated dienes. The regression model with lycopene contributed to 29% in women and 15% in men with beta-carotene of the variation of serum LDL conjugated dienes. Results of the present study suggest that plasma lycopene, lutein and beta-carotene are the most powerful antioxidants for explaining the content of in vivo oxidatively modified LDL in serum.

Total oxidant-scavenging capacities of plasma from glycogen storage disease type Ia patients as measured by cyclic voltammetry, FRAP and luminescence techniques

It has been suggested that the very low incidence of atherosclerosis in glycogen storage disease type Ia (GSD Ia) subjects might be attributed to elevated levels of uric acid, one of the potent low molecular- weight antioxidants found in plasma. The present communication describes a use of two analytical methods-cyclic voltammetry and ferric reducing ability of plasma-and also two chemiluminescence methods to evaluate the total oxidant-scavenging capacities (TOSC) of plasma from GSD Ia patients. Our results verified the elevation of TOSC in GSD Ia patients and we propose the inclusion of luminescence and cyclic voltammetry assays as reliable methods for estimating TOSC in a variety of clinical disorders. Our findings with the cyclic voltammetry method add support to the assumption that the elevated uric acid levels might be the main contributor to plasma antioxidant capacity and possible protection against atherosclerosis.

Plasma antioxidant capacity among middle‐aged men: The contribution of uric acid

OBJECTIVE

Although assays of plasma antioxidant capacity encompass interactions between various antioxidants, uric acid concentration can exert a predominant effect on results. Therefore, individual differences in uric acid concentration may explain a many of the differences in antioxidant capacity. The objective of this study was to measure the antioxidant capacity of plasma samples with and without uric acid in order to provide more information about how the concept of antioxidant capacity could be applied.

MATERIAL AND METHODS

Antioxidant capacity was measured using an enhanced chemiluminescence assay, and uric acid was removed from the samples using uricase.

RESULTS

Antioxidant capacity was positively correlated with uric acid concentration, body mass index, waist circumference, abdominal sagittal diameter and the concentrations of insulin and triglycerides. These correlations were not evident when uric acid was eliminated from the sample, but antioxidant capacity was correlated with lipid concentration; this may partly reflect tocopherols that are transported by lipid molecules.

CONCLUSIONS

The significance of the contribution of uric acid to the antioxidant capacity could differ according to the type of study. Antioxidant capacity measurements in cross-sectional studies may be presented both with and without the contribution of uric acid, because the absence of such data complicates interpretation of results when different populations are compared.

Tocopherol isomer pattern in serum and stool of human following consumption of black currant seed press residue administered in whole grain bread

BACKGROUND & AIMS

Serum gamma-tocopherol is thought to be associated with human health. The dietary influence of tocopherol and fibre-rich black currant seed press residue on serum and stool tocopherol concentration was investigated in a controlled human intervention study.

METHODS

Thirty-six women consumed bread enriched with black currant press residue (4 weeks). The resultant faecal and serum tocopherol concentrations were compared with those after a period consuming control bread without press residue and a normal baseline diet. Fibre intake and excretion, antioxidant capacity (TEAC), and vitamin C concentrations in serum and urine were also determined. Samples were obtained with a 5-day standardised diet at the end of each period.

RESULTS

The press residue bread lead to significantly increased beta-, gamma-, delta- and total tocopherol intake, serum alpha-, beta-, gamma- and total tocopherol concentration (with and without lipid adjustment), fibre intake and urinary vitamin C concentration compared to control bread (P<0.05). Faecal excretion of total tocopherols and fibre increased compared to baseline (P<0.05).

CONCLUSIONS

Fibre intake and excretion influence total tocopherol concentration in lipid-adjusted serum and in stool. The outstandingly high increase of serum gamma-tocopherol concentration through seed press residue consumption could be due to a presumed interruption of the enzymatic tocopherol degradation mechanism by bread constituents.

Antioxidant and redox status after maximal aerobic exercise at high altitude in acclimatized lowlanders and native highlanders

Exercise-induced increase in oxygen consumption leads to oxidative stress. On the contrary, hypoxia triggers oxidative stress despite decreased oxygen flux. Therefore, exercise under hypoxia may aggravate oxidative damage. Highlanders are expected to have better antioxidant capacity than lowlanders as a result of adaptation to hypoxia. The present study was undertaken to investigate the effect of exercise on antioxidant system in lowlanders and highlanders at high altitudes (HA). This study was conducted on active male volunteers, randomly selected and categorized into three groups, i.e., lowlanders tested at sea level (LL-SL, n = 35), lowlanders tested at altitude of 4560 m (LL-HA, n = 35) and native highlanders tested (HAN, n = 20) at the same height. Volunteers performed maximal exercise until exhaustion. Blood samples were collected before and after exercise. Both LL-SL and HAN had shown similar VO2max, which was significantly higher than LL-HA. GSH/GSSG ratio significantly increased in LL-SL and decreased in HAN after exercise. With exercise there were a decrease in superoxide dismutase and increase in glutathione peroxidase and catalase activities in HAN. Therefore, the results have suggested that HAN are more susceptible to oxidative stress when subjected to high-intensity exercise than lowlanders. The cumulative effect of higher VO2max and longer duration of exercise in hypoxia may be the reason of higher level of oxidative insult among HAN. Comparatively better management of antioxidant system observed in lowlanders at HA may be explained by the lower VO2max and shorter duration of exercise in hypoxia.

Effect of Soybean Hypocotyl Extract on Lipid Peroxidation in GK Rats

Vascular complications, as a consequence of atherosclerosis, are main causes of morbidity and mortality in patients with diabetes mellitus. There is increasing evidence that lipid peroxidation and oxidative modification of low density lipoprotein (LDL) is important in atherogenesis. In this study we investigated the effect of soybean hypocotyl extract (SHE), rich in isoflavones and saponins, on lipid peroxide (LPO) levels in liver, plasma and lipoproteins in GK diabetic rats, and its efficacy on the reduction of susceptibility of LDL and high density lipoprotein (HDL) to oxidation. The oxidative modification of LDL and HDL was determined with the lag time of copper ion-induced oxidation curve identified by the conjugated dienes. In SHE group which were fed diet containing 40 g/kg of SHE for 16 weeks, LPO levels in liver, plasma and HDL fraction were significantly decreased compared with the control group. The lag phage of LDL oxidation curve was prolonged noticeably by a mean of 27 min in SHE group as compared to the control group, indicating a reduced susceptibility to oxidation. The results suggest that intake of soybean hypocotyl extract might be useful for the prevention and treatment of diabetes mellitus and diabetes-associated diseases.

Comparison of alanine aminotransferase, white blood cell count, and uric acid in their association with metabolic syndrome: a study of Korean adults

The aim of this study is to investigate the respective associations of alanine aminotransferase (ALT), white blood cell (WBC) count, and uric acid with metabolic syndrome and compare the magnitude in their association with metabolic syndrome, using modified Adult Treatment Panel III (ATP III) and its components. We studies 5,020 Korean adults (20-70 years of age; 2,501 men and 2,519 women) who visited Center for Health Promotion in Pusan National University Hospital for routine health examinations. Metabolic parameters and biochemical markers including ALT, WBC count, and uric acid were obtained. Alcohol intake, smoking status, and the presence of fatty liver were also evaluated. The prevalence of metabolic syndrome was 17.3%. In the partial correlation coefficients adjusted for age, alcohol consumption, smoking status, and presence of fatty liver, ALT was correlated significantly with all components of metabolic syndrome among three markers in men and women respectively. Moreover, ALT showed the highest correlation with HOMA-IR (r=0.311, P<0.001 in men and r=0.285, P<0.001 in women) in both genders. With the increase in the number of metabolic syndrome components, the mean values of all three markers were also significantly increased. In addition, the adjusted mean values of each marker were all significantly increased in metabolic syndrome. In ALT, the adjusted mean values were significantly increased in subjects with all metabolic component disorders. When we calculated odd ratios (ORs) for metabolic syndrome prevalence of the highest quartiles in three markers using multivariate logistic regression analyses, ALT was associated most strongly with metabolic syndrome in both genders (OR 5.65 [95% CI, 3.80 to 8.40]; P<0.001 in men, OR 3.23 [95% CI, 2.15 to 4.86]; P<0.001 in women). The cut-off value for ALT using the ROC curve was 27 IU/L (area under the curve=0.717, sensitivity 62.5%, specificity 70.4%, P<0.001) in men and 18 IU/L (area under the curve=0.735, sensitivity 61.3%, specificity 72.3%, P<0.001) in women. In conclusion, ALT, WBC count, and uric acid play important role as an additional markers for metabolic syndrome. Among three markers, in overlap the multiple risk factors, ALT might have a strong association with metabolic syndrome in Korean adults.

Oxidative stress markers, C-reactive protein and heat shock protein 70 levels in subjects with metabolic syndrome

BACKGROUND

The metabolic syndrome is a cluster of cardiovascular risk factors and essential components of metabolic syndrome are hyperglycemia, hypertension, visceral obesity, hypertriglyceridemia and low high-density lipoprotein cholesterol. Oxidative stress plays a critical role in the pathogenesis of metabolic syndrome components and insulin resistance. The aim of this study was to investigate the role of oxidative stress, C-reactive protein and heat shock protein 70 levels in the pathogenesis of this disease.

METHODS

A total of 36 patients diagnosed with metabolic syndrome and 33 controls were included in the study. Malondialdehyde, carbonyl protein, C-reactive protein and heat shock protein 70 levels and xanthine oxidase and superoxide dismutase activities were measured in the serum of the subjects.

RESULTS

Mean serum malondialdehyde, carbonyl protein, C-reactive protein (p<0.01, p<0.05 and p<0.001, respectively) and xanthine oxidase activity were significantly higher (p<0.01) in serum of the patients than the control group. Superoxide dismutase activity and heat shock protein 70 levels were significantly lower (p<0.01 and p<0.05, respectively) in serum of the patients.

CONCLUSIONS

These results suggest that oxidative stress parameters and components of metabolic syndrome are closely related; therefore, significant alterations may occur in the antioxidant and inflammatory status. However, further studies are required to evaluate the possible molecular mechanisms of heat shock protein 70 levels in metabolic syndrome.

Serum uric acid and incident diabetes in Mauritian Indian and Creole populations

OBJECTIVE

To investigate the predictive value of serum uric acid (UA) for the development of diabetes in Asian Indians and Creoles living in Mauritius.

METHODS

A total of 1941 men (1409 Indians, 532 Creoles) and 2318 non-pregnant women (1645 Indians, 673 Creoles), aged 25-74 years and free of diabetes, cardiovascular disease and gout at baseline examinations in 1987 or 1992, were re-examined in 1992 and/or 1998. Diabetes was determined according to WHO/IDF 2006 criteria. The relationship between baseline UA and the development of diabetes during the follow-up was estimated using interval censored survival analysis.

RESULTS

In this cohort 337 (17.4%) men and 379 (16.4%) women developed diabetes during the follow-up. Individuals who developed diabetes during the follow-up had a lower serum UA levels at follow-up compared with their baseline UA levels, but this is not observed for post-menopausal women. Multivariate adjusted hazard ratios (HRs) (95% CIs) for the development of diabetes corresponding to one S.D. increase in UA concentration at baseline were 1.14 (1.01, 1.30) in Indian men and 1.37 (1.11, 1.68) in Creole men. They were 1.07 (0.95, 1.22) and 1.01 (0.84, 1.22), respectively, in Indians and Creole women.

CONCLUSION

Elevated serum UA is an independent risk marker for future diabetes in Mauritian men, whereas the prediction is weak in women.

Uric acid administration in patients with acute stroke: a novel approach to neuroprotection

Uric acid (UA) is the end product of purine catabolism in humans and is a powerful antioxidant whose generation is increased under ischemic conditions. However, both clinical and experimental studies reveal a gradual exhaustion of the antioxidant capacity after transient cerebral ischemia, and the magnitude of this consumption seems to be correlated with the extent of brain tissue injury, growth of the infarction, severity of neurological impairment in the acute phase, and long-term functional outcome. Growing evidence supports the neuroprotective effect of UA administration after brain ischemia. In experimental conditions, the administration of UA is neuroprotective both in mechanical models of brain ischemia (transient or permanent intraluminal occlusion of the middle cerebral artery) and in thromboembolic models of autologous clot injection. The administration of UA is feasible and safe in healthy volunteers. In acute stroke patients treated with recombinant tissue plasminogen activator (rt-PA), co-administration of UA has proven to reduce lipid peroxidation and to prevent the fall in UA blood levels that occur very early after stroke onset. Currently, a multicentric Phase III clinical trial is testing whether the administration of UA increases the clinical benefits of rt-PA, which represents the only approved therapy in patients with acute ischemic stroke. This review summarizes the available information justifying such a novel therapeutic approach in this devastating clinical condition.

Antioxidant properties of Krebs cycle intermediates against malonate pro-oxidant activity in vitro: A comparative study using the colorimetric method and HPLC analysis to determine malondialdehyde in rat brain homogenates

A variety of Krebs cycle intermediaries has been shown to possess antioxidant properties in different in vivo and in vitro systems. Here we examined whether citrate, succinate, malate, oxaloacetate, fumarate and alpha-ketoglutarate could modulate malonate-induced thiobarbituric acid-reactive species (TBARS) production in rat brain homogenate. The mechanisms involved in their antioxidant activity were also determined using two analytical methods: 1) a popular spectrophotometric method (Ohkawa, H., Ohishi, N., Yagi, K., 1979. Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction. Analytical Biochemistry 95, 351-358.) and a high performance liquid chromatographic (HPLC) procedure (Grotto, D., Santa Maria, L. D., Boeira, S., Valentini, J., Charão, M. F., Moro, A. M., Nascimento, P. C., Pomblum, V. J., Garcia, S. C., 2006. Rapid quantification of malondialdehyde in plasma by high performance liquid chromatography-visible detection. Journal of Pharmaceutical and Biomedical Analysis 43, 619-624.). Citrate, malate, and oxaloacetate reduced both basal and malonate-induced TBARS production. Their effects were not changed by pre-treatment of rat brain homogenates at 100 degrees C for 10 min. alpha-Ketoglutarate increased basal TBARS without changing malonate-induced TBARS production in fresh and heat-treated homogenates. Succinate reduced basal--without altering malonate-induced TBARS production. Its antioxidant activity was abolished by KCN or heat treatment. Fumarate reduced malonate-induced TBARS production in fresh homogenates; however, its effect was completely abolished by heat treatment. There were minimal differences among the studied methods. Citrate, oxaloacetate, malate, alpha-ketoglutarate and malonate showed iron-chelating activity. We suggest that antioxidant properties of citrate, malate and oxaloacetate were due to their ability to cancel iron redox activity by forming inactive complexes, whereas alpha-ketoglutarate and malonate pro-oxidant activity can be due to formation of active complexes with iron. In contrast, succinate and fumarate antioxidant activity was probably due to some enzymatic system.

Diabetes associated with a low serum uric acid level in a general Chinese population

OBJECTIVE

Serum uric acid (UA) is reported as an important marker of hypertension, coronary heart disease, and diabetes; diabetic subjects have low UA levels. The relationship between UA and fasting plasma glucose (FPG) and 2-h plasma glucose concentrations in non-diabetic subjects as well as in diabetic subjects in general population is not well known. This was investigated in a general Chinese population.

METHODS

A stratified, random cluster sampling method was performed to select a representative sample of general population aged 20-74 years in Qingdao in 2002. A total of 1288 men and 2344 women participated in the survey. The mean UA concentration was calculated for small glucose intervals and the trend was tested using general linear model.

RESULTS

The mean concentrations of UA were 381, 393, 371, and 345 micromol/l in men with FPG of <6.1, 6.1-6.9, > or =7.0 mmol/l (newly diagnosed diabetes), and in those with prior history of diabetes. They were 308, 322, 301, and 293 micromol/l, respectively, in women. The UA levels declined with increasing FPG levels in individuals with newly diagnosed diabetes, with standardized coefficient of -0.26 in men and -0.20 in women, after multivariate adjustment for age, body mass index, triglycerides, and cardiovascular disease history. The relationship between 2-h glucose and UA was not as clear as that for FPG.

CONCLUSION

Serum UA levels tended to increase with increasing FPG levels in non-diabetic individuals, but decrease in diabetic individuals.

Treatment of essential hypertension and non-insulin dependent diabetes mellitus with vitamin C

Inappropriate response of the carotid body region to encroachment of its perfusion results in essential hypertension (EH) and/or non-insulin dependent diabetes mellitus (NIDDM). This encroachment is caused by atherosclerosis. The carotid body perceives the encroachment on the lumen as a reduction in the availability of oxygen and glucose for the brain. Raising the perfusion pressure (thus, resulting in EH) and/ or inducing insulin resistance (causing NIDDM) are seen as compensatory mechanisms in response to the primary pathology, ie the encroachment of the lumen by atherosclerosis. Therefore, the reduction or reversal of the atherosclerosis process will help improve perfusion to the carotid bodies, which will in turn reduce or reverse the pathophysiological compensatory adjustments described above. A supplemental therapy, in addition to the standard treatment, with vitamin C is suggested here. The argument in favour of this suggestion is the basis of this paper. Vitamin C is a very important antioxidant. It is suggested to be used without any interference with the usual therapy prescribed for these two chronic diseases. It is recommended to be administered in small, frequent doses of 100mg every 2h, except during sleep. There is no need for compensation for the occasional missed dose. The safety of larger doses of vitamin C than the current recommendations, represents the beauty and is reassuring in recommending this approach.

Antioxidants and coronary artery disease among individuals with type 1 diabetes: Findings from the Pittsburgh Epidemiology of Diabetes Complications Study

OBJECTIVE

Oxidative stress has been implicated in the development of diabetes and cardiovascular disease. We evaluated the effect of serum antioxidants and total antioxidant reserve (TAR) on coronary artery disease (CAD) incidence in type 1 diabetes.

METHODS

Subjects were identified from the Pittsburgh Epidemiology of Diabetes Complications Study (EDC) cohort, a 10-year prospective study of childhood-onset type 1 diabetes. Mean age at baseline was 28 and diabetes duration 19 years. Coronary artery disease was defined as physician-diagnosed angina, confirmed MI, stenosis >or=50%, ischemic electrocardiogram (ECG), or revascularization. Controls were gender, age, and diabetes duration (+/-3 years) matched with cases. Samples and risk factors used in analyses were identified from the earliest exam prior to incidence in cases (54 cases, 67 controls).

RESULTS

None of the antioxidant measures (alpha-tocopherol, gamma-tocopherol, retinol, TAR) showed protection against incident CAD overall. However, a protective effect of alpha-tocopherol against CAD was observed among antioxidant supplement users (HR=0.22, 95% CI=0.10-0.49) and in renal disease (HR=0.46, 95% CI=0.23-0.91). Despite similar alpha-tocopherol concentration, there was no protective effect among nonusers of antioxidant supplements.

CONCLUSIONS

High alpha-tocopherol levels among patients with renal disease and in those using vitamin supplements were associated with lower CAD risk in type 1 diabetes. The specificity of these effects merits further investigation.

Increased scavenger receptor class B type I-mediated cellular cholesterol efflux and antioxidant capacity in the sera of glycogen storage disease type Ia patients

Glycogen storage disease type Ia (GSD-Ia) is characterized by hypercholesterolemia, hypertriglyceridemia, decreased cholesterol in high density lipoprotein and increased cholesterol in low and very low density lipoprotein fractions. Despite this pro-atherogenic lipid profile, GSD-Ia patients are not at elevated risk for atherosclerosis. Studies have shown that reverse cholesterol transport and antioxidant capacity can be protective against atherosclerosis. In this study, we show that sera from GSD-Ia patients are more efficient than sera from control subjects in promoting the scavenger receptor class B type I (SR-BI)-mediated cellular cholesterol efflux, a key component in reverse cholesterol transport. The major determinants of the SR-BI-mediated cholesterol efflux are serum phospholipid (PL) and HDL-PL. Phospholipid and that ratio of HDL-PL to HDL are increased in GSD-Ia patients. We further show that sera from GSD-Ia patients have increased total antioxidant capacity compared to controls and this increase correlates with elevated levels of uric acid, a powerful plasma antioxidant. Taken together, the results suggest that the increase in SR-BI-mediated cellular cholesterol efflux and antioxidant capacity in the sera of GSD-Ia patients may contribute to protection against premature atherosclerosis.

Elevated serum uric acid levels in metabolic syndrome: an active component or an innocent bystander?

Elevated serum uric acid (SUA) levels are commonly seen in patients with the metabolic syndrome (MetS). Several mechanisms, both direct and indirect, connect the increased SUA levels with the established diagnostic criteria of MetS. It is possible that the increased cardiovascular disease risk associated with the MetS is partially attributed to elevated circulating SUA concentration. Several drugs used in the treatment of MetS may alter SUA levels. Thus, lifestyle measures together with the judicious selection of drugs for the treatment of hypertension, dyslipidemia, and insulin resistance associated with MetS may result in a reduction of SUA levels and possibly cardiovascular disease risk. This review summarizes the pathophysiologic association between SUA and MetS and focuses on the prevention of hyperuricemia and its cardiovascular consequences.

Consumption of juice fortified with oregano extract markedly increases excretion of phenolic acids but lacks short- and long-term effects on lipid peroxidation in healthy nonsmoking men

Oregano has been shown to possess antioxidant capacity in various in vitro models and has thus been suggested to be potentially beneficial to human health, but studies in humans are lacking. The aim of this study was to investigate the bioavailability and the effects of Origanum vulgare extract supplementation on serum lipids and lipid peroxidation in healthy nonsmoking men. A four-week double-blinded supplementation trial was concluded in which volunteers (n = 45) were randomized to consume daily mango-orange juice (placebo), mango-orange juice enriched with 300 mg/d total phenolic compounds from oregano extract, or mango-orange juice enriched with 600 mg/d total phenolic compounds from oregano extract. The excretion of phenolic compounds was markedly increased in the higher phenolic group as compared to the placebo group, but no significant changes were observed in the safety parameters, serum lipids, or biomarkers of lipid peroxidation.