Plasma extracellular superoxide dismutase levels in an Australian population with coronary artery disease

Anticonvulsive Effects of Chondroitin Sulfate on Pilocarpine and Pentylenetetrazole Induced Epileptogenesis in Mice

Chondroitin sulfate is a proteoglycan component of the extracellular matrix (ECM) that supports neuronal and non-neuronal cell activity, provides a negative domain to the extracellular matrix, regulates the intracellular positive ion concentration, and maintains the hypersynchronous epileptiform activity. Therefore, the present study hypothesized an antiepileptic potential of chondroitin sulfate (CS) in pentylenetetrazole-induced kindled epilepsy and pilocarpine-induced status epilepticus in mice. Levels of various oxidative stress markers and inflammatory mediators were estimated in the brain tissue homogenate of mice, and histopathological changes were evaluated. Treatment with valproate (110 mg/kg; i.p.) as a standard drug and chondroitin sulfate (100 & 200 mg/kg, p.o.) significantly (p < 0.01) and dose-dependently prevented the severity of kindled and spontaneous recurrent seizures in mice. Additionally, chondroitin sulfate showed its antioxidant potential by restoring the various biochemical levels and anti-inflammatory properties by reducing NF-kB levels and pro-inflammatory mediators like TNF-alpha, IL-1β, and IL-6, indicating the neuroprotective effect as well as the suppressed levels of caspase-3, which indicated a neuroprotective treatment strategy in epilepsy. The proteoglycan chondroitin sulfate restores the normal physiology and configuration of the neuronal tissue. Further, the molecular docking of chondroitin sulfate at the active pockets of TNF-alpha, IL-1β, and IL-6 showed excellent interactions with critical amino acid residues. In conclusion, the present work provides preclinical evidence of chondroitin sulfate as a new therapeutic approach in attenuating and preventing seizures with a better understanding of the mechanism of alteration in ECM changes influencing abnormal neuronal activities.

Impact of EcSOD Perturbations in Cancer Progression

Reactive oxygen species (ROS) are a normal byproduct of cellular metabolism and are required components in cell signaling and immune responses. However, an imbalance of ROS can lead to oxidative stress in various pathological states. Increases in oxidative stress are one of the hallmarks in cancer cells, which display an altered metabolism when compared to corresponding normal cells. Extracellular superoxide dismutase (EcSOD) is an antioxidant enzyme that catalyzes the dismutation of superoxide anion (O₂⁻) in the extracellular environment. By doing so, this enzyme provides the cell with a defense against oxidative damage by contributing to redox balance. Interestingly, EcSOD expression has been found to be decreased in a variety of cancers, and this loss of expression may contribute to the development and progression of malignancies. In addition, recent compounds can increase EcSOD activity and expression, which has the potential for altering this redox signaling and cellular proliferation. This review will explore the role that EcSOD expression plays in cancer in order to better understand its potential as a tool for the detection, predicted outcomes and potential treatment of malignancies.

Obstructive Sleep Apnea and Circulating Biomarkers of Oxidative Stress: A Cross-Sectional Study

Oxidative stress (OS) drives cardiometabolic diseases. Intermittent hypoxia consistently increases oxidative stress markers. Obstructive sleep apnea (OSA) patients experience intermittent hypoxia and an increased rate of cardiovascular disease, however, the impact of OSA on OS markers is not clear. The objective was to assess relationships between OSA severity and biomarker levels. Patients with suspected OSA referred for a polysomnogram (PSG) provided fasting blood sample. Plasma levels of 8-isoprostane, 8-hydroxydeoxyguanosine (8-OHdG), and superoxide dismutase (SOD) were measured. The relationship between OSA and OS was assessed both before and after controlling for confounders (age, sex, smoking history, history of cardiovascular disease, ethnicity, diabetes, statin usage, body mass index (BMI)). 402 patients were studied (68% male, mean age ± SD = 50.8 ± 11.8 years, apnea-hypopnea index (AHI) = 22.2 ± 21.6 events/hour, BMI = 31.62 ± 6.49 kg/m²⁾. In a multivariable regression, the AHI significantly predicted 8-isoprostane levels (p = 0.0008) together with age and statin usage; AHI was not a predictor of 8-OHdG or SOD. Female sex (p < 0.0001) and no previous history of cardiovascular disease (p = 0.002) were associated with increased antioxidant capacity. Circulating 8-isoprostane levels may be a promising biomarker of the severity of oxidative stress in OSA patients. Prospective studies are needed to determine whether this biomarker is associated with long-term cardiometabolic complications in OSA.

Atherothrombosis and Oxidative Stress: Mechanisms and Management in Elderly

SIGNIFICANCE

The incidence of cardiovascular events (CVEs) increases with age, representing the main cause of death in an elderly population. Aging is associated with overproduction of reactive oxygen species (ROS), which may affect clotting and platelet activation, and impair endothelial function, thus predisposing elderly patients to thrombotic complications. Recent Advances: There is increasing evidence to suggest that aging is associated with an imbalance between oxidative stress and antioxidant status. Thus, upregulation of ROS-producing enzymes such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and myeloperoxidase, along with downregulation of antioxidant enzymes, such as superoxide dismutase and glutathione peroxidase, occurs during aging. This imbalance may predispose to thrombosis by enhancing platelet and clotting activation and eliciting endothelial dysfunction. Recently, gut-derived products, such as trimethylamine N-oxide (TMAO) and lipopolysaccharide, are emerging as novel atherosclerotic risk factors, and gut microbiota composition has been shown to change by aging, and may concur with the increased cardiovascular risk in the elderly.

CRITICAL ISSUES

Antioxidant treatment is ineffective in patients at risk or with cardiovascular disease. Further, anti-thrombotic treatment seems to work less in the elderly population.

FUTURE DIRECTIONS

Interventional trials with antioxidants targeting enzymes implicated in aging-related atherothrombosis are warranted to explore whether modulation of redox status is effective in lowering CVEs in the elderly. Antioxid. Redox Signal. 27, 1083-1124.

Unbalanced Oxidant-Antioxidant Status: A Potential Therapeutic Target for Coronary Chronic Total Occlusion in Very Old Patients

Unbalanced oxidant and antioxidant status played an important role in myocardial infarction. The present study was a clinical trial combined preclinically with targeted agent against cardiovascular injuries and ischemia in vivo model. We tried to confirm the association of unbalanced oxidant and antioxidant status with coronary chronic total occlusion (CTO) in 399 very old patients (80~89 years) and investigated the potential therapeutic value of purified polysaccharide from endothelium corneum gigeriae galli (PECGGp). We analyzed levels of circulating superoxide dismutase 3 (SOD3), nitric oxide (NO), endothelial nitric oxide synthase (eNOS), and malondialdehyde (MDA) in very old patients with coronary CTO. Levels of SOD3, NO, eNOS, and MDA in the cardiac tissue were measured in myocardial infarction rats. Levels of SOD3, eNOS, and NO were lowered (p < 0.001) and levels of MDA were increased (p < 0.001). PECGGp treatment increased levels of SOD3, eNOS, and NO (p < 0.01) in cardiac tissue, while decreasing levels of MDA (p < 0.01). PECGGp may suppress unbalanced oxidant and antioxidant status in infarcted myocardium by inhibiting levels of MDA and elevating NO, eNOS, and SOD3 levels. PECGGp could be considered as a potential therapeutic agent for coronary CTO in very old patients.

Elevated Levels of Plasma Superoxide Dismutases 1 and 2 in Patients with Coronary Artery Disease

Aims. To measure plasma levels of superoxide dismutases 1, 2, and 3 (SOD1, 2, 3) and determine whether SODs can function as biomarkers for coronary artery disease (CAD). Patients & Methods. Patient groups were as follows: patients with stable angina pectoris (SAP, n = 33), patients with acute coronary syndrome (ACS, n = 49), and controls (n = 42). Protein quantification was done using ELISA. Results. The concentrations of plasma SOD1 and SOD2 were higher in CAD than in healthy controls. No difference in SOD3 levels between CAD and control groups was found. Limited correlations were found between SODs and gender, age, and severity of coronary artery stenosis. Conclusions. Plasma levels of SOD1 and SOD2 were elevated in patients with CAD and might serve as surrogate biomarkers for CAD.

Erythrocyte superoxide dismutase, glutathione peroxidase, and catalase activities and risk of coronary heart disease in generally healthy women: a prospective study

Erythrocyte antioxidant enzymes are major circulating antioxidant enzymes in the oxidative stress defense system. Few prospective studies have assessed the association between these enzymes and the risk of coronary heart disease (CHD) in generally healthy adults. We conducted a prospective nested case-control study of CHD among 32,826 women at baseline with 15 years of follow-up from 1989 to 2004 in the Nurses' Health Study. We investigated the association of baseline erythrocyte superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) activities with the risk of CHD. A total of 365 cases and 728 controls were included in the analysis. Overall, the relative risks of CHD associated with 1-standard deviation higher SOD, GPx, and CAT activities were 1.07 (95% confidence interval (CI): 0.94, 1.22), 1.04 (95% CI: 0.91, 1.18), and 1.04 (95% CI: 0.92, 1.17), respectively. Multivariable adjustments did not change the associations appreciably. Fasting status did not modify the associations, with the exception that SOD activity was positively associated with the risk of CHD among participants who provided blood samples within 12 hours of fasting. Overall, activities of SOD, GPx, and CAT were not associated with CHD among women who were generally healthy at the time of blood collection.

Redox signaling in cardiovascular health and disease

Spatiotemporal regulation of the activity of a vast array of intracellular proteins and signaling pathways by reactive oxygen species (ROS) governs normal cardiovascular function. However, data from experimental and animal studies strongly support that dysregulated redox signaling, resulting from hyperactivation of various cellular oxidases or mitochondrial dysfunction, is integral to the pathogenesis and progression of cardiovascular disease (CVD). In this review, we address how redox signaling modulates the protein function, the various sources of increased oxidative stress in CVD, and the labyrinth of redox-sensitive molecular mechanisms involved in the development of atherosclerosis, hypertension, cardiac hypertrophy and heart failure, and ischemia-reperfusion injury. Advances in redox biology and pharmacology for inhibiting ROS production in specific cell types and subcellular organelles combined with the development of nanotechnology-based new in vivo imaging systems and targeted drug delivery mechanisms may enable fine-tuning of redox signaling for the treatment and prevention of CVD.

Daily intake of vitamin D- or calcium-vitamin D-fortified Persian yogurt drink (doogh) attenuates diabetes-induced oxidative stress: evidence for antioxidative properties of vitamin D

BACKGROUND

Both poor vitamin D status and oxidative stress (OS) have been independently associated with late diabetic complications, including cardiovascular disease (CVD). The present study aimed to examine the effect of daily intake of vitamin D alone or in combination with calcium as a fortified Persian yogurt drink (doogh) on OS over 12 weeks.

METHODS

Ninety patients with type 2 diabetes aged 30-50 years from both sexes were randomly allocated to one of the three groups to receive two 250-mL bottles of doogh a day, which was either plain (PD; containing 150 mg per 250 mL of calcium and no detectable vitamin D), vitamin D-fortified (DD; containing 150 mg of calcium + 500 IU vitamin D per 250 mL) or calcium-vitamin D-fortified (CDD; 250 mg od calcium + 500 IU vitamin D per 250 mL).

RESULTS

Although mean (SD) serum concentrations of protein carbonyl significantly decreased in both DD and CDD groups [-2.07 (4.39) nm, P = 0.015 and -4.4 (7.64) nm, P = 0.003, respectively], the change in PD group was not significant [-0.54 (6.96) nm, P = 0.674]. A similar pattern was observed for cardiac myeloperoxidase [PD: -19.4 (75.9) μg L(-1) , P = 0.173; DD: -21.8 (54.2) μg L(-1) , P = 0.035, CDD: -48.5 (76.9) μg L(-1) , P = 0.002]. Superoxide dismutase increased significantly only in DD and CDD [56.9 (74.0) U L(-1) , P < 0.001 and 51.6 (119.9) U L(-1) , P = 0.025, respectively]. Changes of serum advanced glycation end-products showed a significant between-group difference among PD, DD and CDD [239.4 (388.4) U L(-1) , -58.1 (147.6) U L(-1) and -143.7 (475.9) U L(-1)  × 10(3) , respectively, P = 0.003], which remained significant after controlling for changes of fasting serum glucose (P = 0.013) and glycated haemoglobin (P = 0.015).

CONCLUSIONS

The findings of the present study demonstrated an OS attenuating effect of vitamin D. However, extra calcium did not convey additional benefit.

Transcriptome-based identification of antioxidative gene expression after fish oil supplementation in normo- and dyslipidemic men

Background

The beneficial effects of omega-3 polyunsaturated fatty acids (n-3 PUFAs), especially in dyslipidemic subjects with a high risk of cardiovascular disease, are widely described in the literature. A lot of effects of n-3 PUFAs and their oxidized metabolites are triggered by regulating the expression of genes. Currently, it is uncertain if the administration of n-3 PUFAs results in different expression changes of genes related to antioxidative mechanisms in normo- and dyslipidemic subjects, which may partly explain their cardioprotective effects. The aim of this study was to investigate the effects of n-3 PUFA supplementation on expression changes of genes involved in oxidative processes.

Methods

Ten normo- and ten dyslipidemic men were supplemented for twelve weeks with fish oil capsules, providing 1.14 g docosahexaenoic acid and 1.56 g eicosapentaenoic acid. Gene expression levels were determined by whole genome microarray analysis and quantitative real-time polymerase chain reaction (qRT-PCR).

Results

Using microarrays, we discovered an increased expression of antioxidative enzymes and a decreased expression of pro-oxidative and tissue enzymes, such as cytochrome P450 enzymes and matrix metalloproteinases, in both normo- and dyslipidemic men. An up-regulation of catalase and heme oxigenase 2 in both normo- and dyslipidemic subjects and an up-regulation of cytochrome P450 enzyme 1A2 only in dyslipidemic subjects could be observed by qRT-PCR analysis.

Conclusions

Supplementation of normo- and dyslipidemic subjects with n-3 PUFAs changed the expression of genes related to oxidative processes, which may suggest antioxidative and potential cardioprotective effects of n-3 PUFAs. Further studies combining genetic and metabolic endpoints are needed to verify the regulative effects of n-3 PUFAs in antioxidative gene expression to better understand their beneficial effects in health and disease prevention.

Trial registration

ClinicalTrials.gov (ID: NCT01089231)

Effects and mechanism of turmeric vasorelaxation of the thoracic aorta in hypercholesterolemic rats

An extract of Curcuma longa was tested in hypercholesterolemic rats to investigate its potential therapeutic effect on vascular conditions. Four experimental groups were used: normal diet (ND) control group, high cholesterol diet (HCD) group, and HCD subgroups supplemented with turmeric extract at 100 or 300 mg/kg of body weight (HCD100Tur and HCD300Tur groups, respectively). Turmeric extract was fed orally to animals, and dietary treatments lasted for 28 days. Hypercholesterolemia developed in the HCD, HCD100Tur, and HCD300Tur rats. Segments of the thoracic aorta were isolated, and an organ bath experiment was used to assess the vasorelaxation capability among all rats. Rats fed only HCD showed a marked decrease in acetylcholine-induced vasorelaxation compared with ND control rats. The HCD100Tur and HCD300Tur rats showed significant improvement in vasorelaxation compared with HCD rats. When vasorelaxation was induced by high concentrations of sodium nitroprusside, no differences in vasorelaxation were observed among the four groups of rats. A mechanistic study showed that HCD100Tur and HCD300Tur rats had significantly higher levels of the antioxidant enzymes superoxide dismutase and glutathione peroxidase than HCD rats. The transcript levels of heat shock protein 70 (hsp70), bcl2, bax-α, caspase (casp3), and glyceraldehyde 3-phosphate dehydrogenase in aortic tissues indicated that hypercholesterolemia significantly increased the expression of bax-α and casp3 but down-regulated bcl2 expression compared with the control group. Turmeric increased the expression of hsp70 and bcl2 but greatly reduced casp3 expression, indicating that turmeric improves vasorelaxation of the aorta in hypercholesterolemic rats by increasing antioxidant enzyme activities and likely suppressing apoptosis.

Is the Western diet adequate in copper?

Copper has been known to be essential for health for more than three quarters of a century. Myriad experiments with animals reveal that the cardiovascular, musculoskeletal and nervous systems are most sensitive to deficiency. Copper in the Western diet has been decreasing at least since the 1930s; half of the adult population consumes less than the amount recommended in the European Communities and the United Kingdom. At least one fourth of adults consume less than the estimated average requirement published for the United States and Canada. Hundreds of people have been reported in journals about medicine and neurology rather than nutrition to have impaired copper nutriture based on the criteria of low copper concentrations and low activities of enzymes dependent on copper in various fluids and tissues. In contrast, only 46 people have participated in depletion/repletion experiments needed to define requirements. Almost 1000 people have benefited from supplements containing copper in controlled trials. People deficient in copper are being identified increasingly; it is unknown if unusually high requirements or unusually low diets are causal. Alzheimer's disease, ischemic heart disease and osteoporosis are the most likely human illnesses from low copper intakes.

Superoxide dismutases: role in redox signaling, vascular function, and diseases

Excessive reactive oxygen species Revised abstract, especially superoxide anion (O₂•-), play important roles in the pathogenesis of many cardiovascular diseases, including hypertension and atherosclerosis. Superoxide dismutases (SODs) are the major antioxidant defense systems against (O₂•-), which consist of three isoforms of SOD in mammals: the cytoplasmic Cu/ZnSOD (SOD1), the mitochondrial MnSOD (SOD2), and the extracellular Cu/ZnSOD (SOD3), all of which require catalytic metal (Cu or Mn) for their activation. Recent evidence suggests that in each subcellular location, SODs catalyze the conversion of (O₂•-), H2O2, which may participate in cell signaling. In addition, SODs play a critical role in inhibiting oxidative inactivation of nitric oxide, thereby preventing peroxynitrite formation and endothelial and mitochondrial dysfunction. The importance of each SOD isoform is further illustrated by studies from the use of genetically altered mice and viral-mediated gene transfer. Given the essential role of SODs in cardiovascular disease, the concept of antioxidant therapies, that is, reinforcement of endogenous antioxidant defenses to more effectively protect against oxidative stress, is of substantial interest. However, the clinical evidence remains controversial. In this review, we will update the role of each SOD in vascular biologies, physiologies, and pathophysiologies such as atherosclerosis, hypertension, and angiogenesis. Because of the importance of metal cofactors in the activity of SODs, we will also discuss how each SOD obtains catalytic metal in the active sites. Finally, we will discuss the development of future SOD-dependent therapeutic strategies.

Evaluation of status of zinc, copper, and iron levels in biological samples of normal children and children with night blindness with age groups of 3-7 and 8-12 years

The causes of night blindness in children are multifactorial, and particular consideration has been given to childhood nutritional deficiency, which is the most common problem found in underdeveloped countries. Such deficiency can result in physiological and pathological processes that in turn influence hair composition. This study was designed to compare the levels of zinc (Zn), copper (Cu), and iron (Fe) in scalp hair, blood, and urine of both genders of children with night blindness with age range of 3-7 and 8-12 years, comparing them to sex- and age-matched controls. A microwave-assisted wet acid digestion procedure was developed as a sample pretreatment, for the determination of zinc, copper, and iron in biological samples of children with night blindness. The proposed method was validated by using conventional wet digestion and certified reference samples of hair, blood, and urine. The digests of all biological samples were analyzed for Cu, Fe, and Zn by flame atomic absorption spectrometry using an air/acetylene flame. The results indicated significantly lower levels of Fe, Cu, and Zn in the biological samples (blood and scalp hair) of male and female children with night blindness, compared with control subjects of both genders. These data present guidance to clinicians and other professionals investigating the deficiency of essential trace metals in biological samples (scalp hair and blood) of children with night blindness.

Skin autofluorescence is elevated in acute myocardial infarction and is associated with the one-year incidence of major adverse cardiac events

BACKGROUND.: ST-elevation myocardial infarction (STEMI) is associated with increased inflammation and oxidative stress, enhancing the formation of advanced glycation endproducts (AGEs). These encompass a characteristic fluorescence pattern, which can be non-invasively measured as skin autofluorescence (AF). In this study we investigate whether skin AF is elevated in STEMI, its association with inflammatory and glycaemic stress and its predictive value for future events. METHODS.: Skin AF was measured in 88 STEMI patients (mean age 64+/-13 years) within 72 hours and around six months after discharge, in 81 stable coronary artery disease (sCAD) patients (64+/-10 years), and in 32 healthy controls (63+/-11 years). The cumulative one-year incidence of all-cause mortality and hospitalisation for myocardial infarction or heart failure was documented. RESULTS.: Skin AF was significantly higher in STEMI compared with sCAD and controls, irrespective of confounders, and was associated with HbA1c and C-reactive protein. Skin AF decreased significantly in STEMI patients, when measured >200 days after discharge. In STEMI patients, skin AF above the median was predictive of future events (hazard ratio 11.6, 95% CI 1.5 to 90.8, p=0.019). CONCLUSION.: Skin AF is elevated in STEMI, is associated with inflammation and glycaemic stress, and predicts future major adverse cardiac events. (Neth Heart J 2009;17:162-8.Neth Heart J 2009;17:162-8.).

Inhibition of gene expression of heparin-binding epidermal growth factor-like growth factor by extracellular superoxide dismutase in rat aortic smooth muscle cells

Both extracellular superoxide dismutase (EC-SOD) and heparin binding EGF like growth factor (HB-EGF) are produced in smooth muscle cells of the arterial wall, and are thought to play pathological roles in atherosclerosis with heparin binding characteristics. EC-SOD treatment clearly reduced the H2O2 induced expression of HB-EGF in rat aortic smooth muscle cells (RASMC). EC-SOD also inhibited the induction of HB-EGF by 12-O-tetradecanoylphorbol-13-acetate (TPA) in RASMC by 60%. Both H2O2 and TPA increased intracellular ROS levels, and EC-SOD inhibited ROS generation only for the case of H2O2 but not TPA. Treatment of the cells with heparin alone decreased HB-EGF expression by 20%, whereas EC-SOD alone and a co-incubation with EC-SOD and heparin suppressed the induction by 60 and 70%, respectively. These results suggest that EC-SOD is related to the EGF signaling in two ways, competition for HSPG with HB-EGF and as an ROS scavenger.

Atherogenic dyslipidemia and oxidative stress: a new look

Although results from in vitro studies and clinical trials demonstrate strong associations between oxidative stress and cardiovascular risk, to date still no convincing data are available to suggest that treatment with antioxidants might reduce vascular events. Oxidative modifications of low-density lipoproteins (LDL) represent an early stage of atherosclerosis, and small, dense LDL are more susceptible to oxidation than larger, more buoyant particles. Oxidized LDL are independent predictors of subclinical and clinical atherosclerosis. Recent studies suggested that novel therapeutic strategies may take into account the removal of such particles from circulation. Future research is required to explore the potential synergistic impact of markers of oxidative stress and atherogenic dyslipidemia, particularly small dense LDL, on cardiovascular risk.

Lycium barbarum (goji) juice improves in vivo antioxidant biomarkers in serum of healthy adults

Although Lycium barbarum (goji) and active compounds, Lycium barbarum polysaccharides (LBP), have a high in vitro antioxidant score as determined by simple chemical reaction methods, their in vivo antioxidant effects in humans have not been extensively examined. After our earlier report that an LBP-standardized Lycium barbarum preparation (GoChi) helps prevent oxidant stress-related conditions in humans, our present study examined the hypothesis that the antioxidant effects of GoChi result from its ability to enhance endogenous antioxidant factors. We investigated the effects of GoChi in a 30-day randomized, double-blind, placebo-controlled clinical study. The study population included 50 Chinese healthy adults aged 55 to 72 years. In vivo antioxidant markers, consisting of serum levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and lipid peroxidation (indicated by decreased levels of malondialdehyde, MDA) were examined preintervention and postintervention with GoChi or placebo (120 mL/d). In the GoChi group, antioxidant markers significantly increased by 8.4% for SOD and 9.9% for GSH-Px between the preintervention and postintervention measurements, whereas MDA were significantly decreased by 8.7%. In addition, the SOD, GSH-Px, and MDA levels in the GoChi group were significantly different from those in the placebo group at the postintervention time point, with increases of 8.1% and 9.0% and a decrease of 6.0%, respectively. No significant differences were detected between the preintervention and postintervention time points in the placebo group. These results indicate that GoChi increased antioxidant efficacies in humans by stimulating endogenous factors and suggest that continued use beyond 30 days might help prevent or reduce free radical-related conditions.

Extracellular superoxide dismutase (ecSOD) in vascular biology: an update on exogenous gene transfer and endogenous regulators of ecSOD

Extracellular superoxide dismutase (ecSOD) is the major extracellular scavenger of superoxide (O(2)(.-)) and a main regulator of nitric oxide (NO) bioactivity in the blood vessel wall, heart, lungs, kidney, and placenta. Involvement of O(2)(.-) has been implicated in many pathological processes, and removal of extracellular O(2)(.-) by ecSOD gene transfer has emerged as a promising experimental technique to treat vascular disorders associated with increased oxidant stress. In addition, recent studies have clarified mechanisms that regulate ecSOD expression, tissue binding, and activity, and they have provided new insight into how ecSOD interacts with other factors that regulate vascular function. Finally, studies of a common gene variant in humans associated with disruption of ecSOD tissue binding suggest that displacement of the enzyme from the blood vessel wall may contribute to vascular diseases. The purpose of this review is to summarize recent research findings related to ecSOD function and gene transfer and to stimulate other investigations into the role of this unique antioxidant enzyme in vascular pathophysiology and therapeutics.

Gene expression profile in obesity and type 2 diabetes mellitus

Obesity is an important component of metabolic syndrome X and predisposes to the development of type 2 diabetes mellitus. The incidence of obesity, type 2 diabetes mellitus and metabolic syndrome X is increasing, and the cause(s) for this increasing incidence is not clear. Although genetics could play an important role in the higher prevalence of these diseases, it is not clear how genetic factors interact with environmental and dietary factors to increase their incidence. We performed gene expression profile in subjects with obesity and type 2 diabetes mellitus with and without family history of these diseases. It was noted that genes involved in carbohydrate, lipid and amino acid metabolism pathways, glycan of biosynthesis, metabolism of cofactors and vitamin pathways, ubiquitin mediated proteolysis, signal transduction pathways, neuroactive ligand-receptor interaction, nervous system pathways, neurodegenerative disorders pathways are upregulated in obesity compared to healthy subjects. In contrast genes involved in cell adhesion molecules, cytokine-cytokine receptor interaction, insulin signaling and immune system pathways are downregulated in obese. Genes involved in signal transduction, regulation of actin cytoskeleton, antigen processing and presentation, complement and coagulation cascades, axon guidance and neurodegenerative disorders pathways are upregulated in subjects with type 2 diabetes with family history of diabetes compared to those who are diabetic but with no family history. Genes involved in oxidative phosphorylation, immune, nervous system, and metabolic disorders pathways are upregulated in those with diabetes with family history of diabetes compared to those with diabetes but with no family history. In contrast, genes involved in lipid and amino acid pathways, ubiquitin mediated proteolysis, signal transduction, insulin signaling and PPAR signaling pathways are downregulated in subjects with diabetes with family history of diabetes. It was noted that genes involved in inflammatory pathway are differentially expressed both in obesity and type 2 diabetes. These results suggest that genes concerned with carbohydrate, lipid and amino acid metabolic pathways, neuronal function and inflammation play a significant role in the pathobiology of obesity and type 2 diabetes.

Is metabolic syndrome X a disorder of the brain with the initiation of low-grade systemic inflammatory events during the perinatal period?

An imbalance between pro- and anti-inflammatory molecules occurs in metabolic syndrome X. High-energy diet, saturated fats and trans-fats during perinatal period could suppress Delta(6) and Delta(5) desaturases both in the maternal and fetal tissues, resulting in a decrease in the concentrations of long-chain polyunsaturated fatty acids (LCPUFAs): arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) that have a negative feedback control on inflammation. EPA, DHA and AA augment endothelial nitric oxide synthesis, potentiate insulin action both in the peripheral tissues and brain and alter leptin production. LCPUFAs are essential for brain growth and development and synaptogenesis and modulate the action of several neurotransmitters and hypothalamic peptides. This suggests that metabolic syndrome X could be a disorder of the brain due to suboptimal LCPUFAs during perinatal period that triggers low-grade systemic inflammation, implying that perinatal strategies are needed to prevent its development.

Effect of Homocysteine-Induced Oxidative Stress on Endothelial Function in Coronary Slow-Flow

BACKGROUND AND OBJECTIVE

Coronary slow-flow (CSF) phenomenon is characterized by delayed opacification of vessels in a normal coronary angiogram, but its etiopathogenesis remains unclear. Plasma homocysteine (Hcy) level can severely disturb vascular endothelial function and may play a role in the pathogenesis of CSF. In our study, endothelial function in patients with CSF and their relationship with Hcy and oxidative stress parameters are investigated.

METHOD

Forty-four patients with angiographically proven CSF and 44 cases with normal coronary flow pattern with similar risk profile were enrolled in the study. Coronary flow patterns of the cases are determined by Thrombolysis in Myocardial Infarction (TIMI) frame count method. Endothelium dependent flow mediated dilatation (FMD) and independent vasodilatation characteristics are evaluated by high frequency ultrasound over the brachial artery. Superoxide dismutase (SOD) and reduced glutathione (GSH) and reduction of oxidative material in the body and the end product of lipid peroxidation, malondialdehyde (MDA) are measured as oxidative stress markers in blood samples.

RESULTS

Plasma Hcy level (micromol/l) of patients with CSF was found to be significantly higher than in controls (12.2 +/- 4.9 vs. 8.5 +/- 2.8, p = 0.0001). FMD was 7.87 +/- 2.0% in controls and 4.98 +/- 1.1% in patients with CSF (p = 0.0001). GSH was reduced in patients with CSF. SOD and MDA activity were found higher in patients with CSF than control subjects. Plasma Hcy level was significantly positively correlated with mean TIMI frame count and negatively correlated with FMD in correlation analysis (r = 0.58, p = 0.0001; r = -0.41, p = 0.022; respectively).

CONCLUSION

The present findings allow us to conclude that patients with CSF have increased levels of Hcy and oxidative stress markers and impaired endothelial cell function.

Correlation of oxidative stress parameters and inflammatory markers in coronary artery disease patients

OBJECTIVES

In addition to many traditional risk factors for coronary artery disease (CAD) development, enhanced oxidative stress and inflammation are serious conditions that may also be classified as novel risk factors. In the present study, we assessed the relationship between several parameters of oxidative stress status [malonaldehyde (MDA), superoxide anion (O(2)(-)) and plasma and erythrocyte superoxide dismutase (SOD) activities] with high sensitivity C-reactive protein (hsCRP) and fibrinogen as inflammation markers.

DESIGN AND METHODS

Oxidative stress status parameters, inflammation markers and lipid status parameters were measured in 385 subjects [188 coronary heart disease (CHD) patients with angiographically diagnosed coronary artery disease (CAD), 141 patients with occlusion >50% in at least one major coronary artery (CAD+) and 47 patients with occlusion less than 50% (CAD-), and 197 CHD-free middle-aged subjects (the control group)].

RESULTS

The plasma MDA concentration and the level of O(2)(-) in plasma were significantly higher in combination with significantly lower SOD activity in the CAD+ group vs. the control group. By using multiple stepwise regression analysis, fibrinogen and hsCRP showed independent correlation with MDA. Binary logistic regression analysis indicated that both MDA and O(2)(-) were significantly associated with CAD development and adjustment for inflammatory markers weakened this association in the case of MDA.

CONCLUSIONS

The relationship between oxidative stress parameters and inflammatory species suggest their strong mutual involvement in atherosclerosis development that leads to CAD progression.

Heparin-released extracellular superoxide dismutase is reduced in patients with coronary artery atherosclerosis

OBJECTIVES

We studied whether the amount of heparin-released extracellular superoxide dismutase (EC-SOD), which is an antioxidative enzyme, is associated with coronary artery disease (CAD).

METHODS AND RESULTS

EC-SOD was measured in plasma at basal and at post-heparin injection in 315 patients. Heparin-released EC-SOD was calculated as the difference between the two values. After exclusion of a mutant EC-SOD group (n = 27:8.6%), 288 patients were divided into three groups by angiographic findings; those with normal coronary (the normal group; n = 63), those with atherosclerosis without significant stenosis (the mild atherosclerosis group; n = 36), and those with significant stenosis (the atherosclerosis group; n = 189). Although the basal values were similar among the three groups, heparin-released EC-SOD levels were significantly lower in the atherosclerosis group (131.0 +/- 42.8 ng/ml, p = 0.0003) than in the normal group (156.9 +/- 66.2 ng/ml). Moreover, logistic analysis revealed that heparin-released EC-SOD independently contributed to CAD. The coronary score showed a significant correlation with heparin-released EC-SOD. As for factors affecting the level of heparin-released EC-SOD, the level of high-density lipoprotein cholesterol and age showed a positive correlation.

CONCLUSIONS

The results suggest that heparin-released EC-SOD is significantly reduced in CAD and that the tissue-bound location of this enzyme might be important for antioxidative function.

Evaluation of essential and toxic metals by ultrasound-assisted acid leaching from scalp hair samples of children with macular degeneration patients

BACKGROUND

The causes of night blindness in children are multifactorial and particular consideration has been given to childhood nutritional deficiency, which is the most common problem found in underdeveloped countries. Such deficiency can result in physiological and pathological processes that in turn influence hair composition.

METHOD

An ultrasonic-assisted acid leaching procedure was developed as a sample pretreatment for the determination of Zn, Cu, Cd, As and Pb in human scalp hair samples of night blindness male children with age between 5 to 15 y and compared with the children without vision anomalies that lived in the same localities. The effects of different factors on acid leaching of metals, such as preintensification time (without ultrasonic stirring) after treatment of acid mixture, exposure time to ultrasound and temperature of the ultrasonic bath have been investigated. The proposed method was validated by certified reference samples of scalp hair CRM 397. The wet acid digestion method was used to obtain the total metal concentration in both scalp hair and CRM samples. Cu and Zn in leachates and digests were measured by flame atomic absorption spectrometry (FAAS) using a conventional air/acetylene flame, while Cd and Pb were determined by electrothermal atomic absorption spectrometry (ETAAS) under optimized conditions.

RESULTS

It was observed that at optimal conditions, the recovery for Zn, Cd, Pb, As and Cu were 98%, 98.5%, 96%, 97.2% and 94% respectively. The mean values of Zn and Cu in scalp hair samples of children having night blindness were significantly lower as compared to normal healthy children (p for Zn<0.001 and Cu<0.003), while the level of toxic metals As, Cd and Pb were significantly higher in children having ocular problems as related to normal children (p As<0.0074, Cd<0.001 and lead<0.004).

CONCLUSION

These data present guidance to clinicians and other professional investigating deficiency of essential trace metals and excessive level of toxic metals in biological samples.

Decreased plasma extracellular superoxide dismutase level in patients with vasospastic angina

OBJECTIVE

Extracellular superoxide dismutase (EC-SOD) is the major extracellular scavenger of superoxides, and one of the main regulators of nitric oxide bioactivity in vessel walls. Here, we examined whether plasma EC-SOD level was associated with vasospastic angina (VSA), and if it was a risk factor for VSA.

METHODS AND RESULTS

We assigned 105 patients with normal or mildly stenotic coronary arteries into either a VSA (n=58) or chest pain syndrome (CPS) (n=47) groups. Plasma EC-SOD and other biochemical variables were measured, and major coronary risk factors were assessed. Results showed that apart from smoking status there were no significant differences in patient characteristics and biochemical variables between the two groups. In the VSA group, prevalence of smoking was significantly higher (53% versus 26%, p=0.0055), and plasma EC-SOD level was significantly lower (68.9+/-18.5 ng/ml versus 83.8+/-25.9 ng/ml; p=0.0009). Not only smoking (OR 2.742, 95% CI 1.032-7.287, p=0.0431) but also plasma EC-SOD (OR 0.971, 95% CI 0.949-0.993, p=0.0102) was an independent risk factor for VSA.

CONCLUSIONS

In patients with VSA, plasma EC-SOD level was substantially reduced. Furthermore, plasma EC-SOD level followed by cigarette smoking was the most predictive risk factor for coronary spasms.

Extracellular superoxide dismutase gene polymorphism is associated with insulin resistance and the susceptibility to type 2 diabetes

Oxidative stress has been implicated in pancreatic beta-cell damage, insulin resistance and vascular function in diabetic patients and the dysfunction of antioxidant enzymes may be associated with the pathogenesis of diabetes. Extracellular superoxide dismutase (EC-SOD) is found in the extracellular matrix of tissues and the major scavenger of superoxide radical. To investigate the role of genetic variability for the pathogenesis of type 2 diabetes, we scanned the protein coding exon and flanking introns of EC-SOD gene for mutation in Japanese type 2 diabetic patients. We identified two missense mutations, Ala40Thr (GCG-->ACG) and Arg213Gly (CGG-->GGG), and a silent mutation, Leu53Leu (CTG-->TTG). For one of these variants, the Ala40Thr polymorphism, the frequency of Thr allele and the number of subjects with Thr allele (Ala/Thr+Thr/Thr) were higher in type 2 diabetic patients (n=205) than those in non-diabetic subjects (n=220) (33.2% versus 24.1%, p=0.003 and 55.6% versus 42.7%, p=0.008, respectively). The patients with Thr allele also showed earlier age at diagnosis of diabetes (42.2+/-7.8 years versus 44.4+/-6.9 years, p=0.037) and higher prevalence of hypertension (53.5% versus 38.5%, p=0.032) than those without the allele. Insulin sensitivity, furthermore, was evaluated in 71 type 2 diabetic patients with short insulin tolerance test (SITT). The patients with Thr allele showed lower insulin sensitivity (Kitt value of SITT) than those without the allele (1.78+/-0.78%/min versus 2.33+/-1.02%/min, p=0.012), although no significant differences in other clinical and biochemical characteristics were observed between two groups. These results suggest that the genetic variant of EC-SOD gene is associated with insulin resistance and the susceptibility to type 2 diabetes.

Cigarette Smoking Induced Oxidative Stress may Impair Endothelial Function and Coronary Blood Flow in Angiographically Normal Coronary Arteries

BACKGROUND

Smoking contributes to the progression of atherosclerotic heart disease by causing endothelial dysfunction. In the present study the effect of smoking on endothelial functions and coronary flow was investigated, as well as the relationship of these factors with oxidative stress parameters, in subjects with normal coronary arteries.

MATERIALS AND RESULTS

The study group comprised 87 patients with angiographically normal coronary arteries (36 smokers, 51 nonsmokers). Coronary flow patterns were determined by the Thrombolysis In Myocardial Infarction (TIMI) frame count method. Endothelial function was evaluated by high-frequency ultrasound imaging of the brachial artery. Superoxide dismutase (SOD) and reduced glutathione (GSH) and reduction of oxidative material in the body and the endproduct of lipid peroxidation, malondialdehyde (MDA), were measured as oxidative stress markers. Mean TIMI frame count was significantly higher in smokers than nonsmokers (42.2 +/- 16 vs 29.5 +/- 9.5, p = 0.0001). Endothelium-dependent flow-mediated dilatation was 6.81+/-1.95% in nonsmokers and 5.7 +/- 2.2% in smokers (p = 0.0001). The smokers had dramatically higher levels of SOD and MDA and lower levels of GSH than the nonsmoker group.

CONCLUSION

Smoking induced oxidative stress deteriorates coronary blood flow by disturbing endothelial function.

Extracellular superoxide dismutase and oxidant damage in osteoarthritis

OBJECTIVE

To use human cartilage samples and a mouse model of osteoarthritis (OA) to determine whether extracellular superoxide dismutase (EC-SOD) is a constituent of cartilage and to evaluate whether there is a relationship between EC-SOD deficiency and OA.

METHODS

Samples of human cartilage were obtained from femoral heads at the time of joint replacement surgery for OA or femoral neck fracture. Samples of mouse tibial cartilage obtained from STR/ort mice and CBA control mice were compared at 5, 15, and 35 weeks of age. EC-SOD was measured by enzyme-linked immunosorbent assay, Western blotting, and immunohistochemistry techniques. Real-time quantitative reverse transcription-polymerase chain reaction was used to measure messenger RNA for EC-SOD and for endothelial cell, neuronal, and inducible nitric oxide synthases. Nitrotyrosine formation was assayed by Western blotting in mouse cartilage and by fluorescence immunohistochemistry in human cartilage.

RESULTS

Human articular cartilage contained large amounts of EC-SOD (mean +/- SEM 18.8 +/- 3.8 ng/gm wet weight of cartilage). Cartilage from patients with OA had an approximately 4-fold lower level of EC-SOD compared with cartilage from patients with hip fracture. Young STR/ort mice had decreased levels of EC-SOD in tibial cartilage before histologic evidence of disease occurred, as well as significantly more nitrotyrosine formation at all ages studied.

CONCLUSION

EC-SOD, the major scavenger of reactive oxygen species in extracellular spaces, is decreased in humans with OA and in an animal model of OA. Our findings suggest that inadequate control of reactive oxygen species plays a role in the pathophysiology of OA.

The high concentration of Arg213-->Gly extracellular superoxide dismutase (EC-SOD) in plasma is caused by a reduction of both heparin and collagen affinities

The C-terminal region of EC-SOD (extracellular superoxide dismutase) mediates the binding to both heparin/heparan sulphate and type I collagen. A mutation (Arg213-->Gly; R213G) within this extracellular matrix-binding region has recently been implicated in the development of heart disease. This relatively common mutation affects the heparin affinity, and the concentration of EC-SOD in the plasma of R213G homozygous individuals is increased 10- to 30-fold. In the present study we confirm, using R213G EC-SOD purified from a homozygous individual, that the heparin affinity is reduced. Significantly, the collagen affinity of the R213G EC-SOD variant was similarly affected and both the heparin and collagen affinities were reduced by 12-fold. Structural analysis of synthetic extracellular matrix-binding regions suggests that the mutation alters the secondary structure. We conclude that the increased concentration of EC-SOD in the plasma of R213G carriers is caused by a reduction in both heparin and collagen affinities.

Pre-emptive gene therapy using recombinant adeno-associated virus delivery of extracellular superoxide dismutase protects heart against ischemic reperfusion injury, improves ventricular function and prolongs survival

In high-risk patients, the ideal cardiovascular gene therapy requires a strategy that provides long-term protection of myocardium against episodes of ischemic/reperfusion injury. We report the development of an efficient, long-lasting pre-emptive gene therapy strategy in a rat model of ischemic-reperfusion (I/R) injury of heart. At 6 weeks prior to myocardial injury, the human extracellular superoxide dismutase (Ec-SOD) gene was delivered by direct intramyocardial injections, using a recombinant adeno-associated virus vector. Significant myocardial protection was documented by the decrease in infarct size at 24 h post I/R, improved left ventricular function at 7 weeks postinjury, and enhanced long-term survival in the SOD treated group. This concept of preinjury delivery and 'pre-emptive' gene therapy via the expression of a secreted protein that renders paracrine therapeutic action can be an effective strategy for organ protection against future injury.

The intracellular proteolytic processing of extracellular superoxide dismutase (EC-SOD) is a two-step event

Extracellular superoxide dismutase (EC-SOD) is a tetramer composed of either intact (Trp(1)-Ala(222)) or proteolytically cleaved (Trp(1)-Glu(209)) subunits. The latter form is processed intracellularly before secretion and lacks the C-terminal extracellular matrix (ECM)-binding region ((210)RKKRRRESECKAA(222)-COOH). We have previously suggested that the C-terminal processing of EC-SOD is either a one-step mechanism accomplished by a single intracellular endoproteolytic event cleaving the Glu(209)-Arg(210) peptide bond or a two-step mechanism involving two proteinases (Enghild, J. J., Thogersen, I. B., Oury, T. D., Valnickova, Z., Hojrup, P., and Crapo, J. D. (1999) J. Biol. Chem. 274, 14818-14822). In the latter case, an initial endoproteinase cleavage occurs somewhere in the region between Glu(209) and Glu(216). A carboxypeptidase specific for basic amino acid residues subsequently trims the remaining basic amino acid residues to Glu(209). A naturally occurring mutation of EC-SOD substituting Arg(213) for Gly enabled us to test these hypotheses. The mutation does not prevent proteolysis of the ECM-binding region but prevents a carboxypeptidase B-like enzyme from trimming residues beyond Gly(213). The R213G mutation is located in the ECM-binding region, and individuals carrying this mutation have an increased concentration of EC-SOD in the circulatory system. In this study, we purified the R213G EC-SOD variant from heterozygous or homozygous individuals and determined the C-terminal residue of the processed subunit to be Gly(213). This finding supports the two-step processing mechanism and indicates that the R213G mutation does not disturb the initial endoproteinase cleavage event but perturbs the subsequent trimming of the C terminus.

Extracellular superoxide dismutase in biology and medicine

Accumulated evidence has shown that reactive oxygen species (ROS) are important mediators of cell signaling events such as inflammatory reactions (superoxide) and the maintenance of vascular tone (nitric oxide). However, overproduction of ROS such as superoxide has been associated with the pathogenesis of a variety of diseases including cardiovascular diseases, neurological disorders, and pulmonary diseases. Antioxidant enzymes are, in part, responsible for maintaining low levels of these oxygen metabolites in tissues and may play key roles in controlling or preventing these conditions. One key antioxidant enzyme implicated in the regulation of ROS-mediated tissue damage is extracellular superoxide dismutase (EC-SOD). EC-SOD is found in the extracellular matrix of tissues and is ideally situated to prevent cell and tissue damage initiated by extracellularly produced ROS. In addition, EC-SOD is likely to play an important role in mediating nitric oxide-induced signaling events, since the reaction of superoxide and nitric oxide can interfere with nitric oxide signaling. This review will discuss the regulation of EC-SOD and its role in a variety of oxidant-mediated diseases.

Serum extracellular superoxide dismutase in patients with type 2 diabetes: relationship to the development of micro- and macrovascular complications

OBJECTIVE

The aim of this study was to determine the distribution of serum extracellular superoxide dismutase (EC-SOD) concentrations in patients with type 2 diabetes and to assess whether increased EC-SOD concentration is associated with the development of diabetic vascular complications.

RESEARCH DESIGN AND METHODS

Serum EC-SOD concentrations were determined in 222 patients with type 2 diabetes and 75 healthy control subjects by an enzyme-linked immunosorbent assay. All subjects had the EC-SOD domain genotyped.

RESULTS

The serum EC-SOD concentrations showed a distinct bimodal distribution in both patients with diabetes and control subjects. All subjects with the high-level phenotype carried the Arg213Gly mutation. The frequency of this variant was similar in the diabetes and control groups. Within the group of subjects with the common EC-SOD phenotype, the serum EC-SOD concentration (mean +/- SE) was significantly higher in patients with type 2 diabetes (99.3 +/- 1.3 ng/ml) compared with the control subjects (68.4 +/- 2.3 ng/ml, P < 0.01). Stepwise multiple regression analysis of the data from the diabetic common phenotype group showed a significant relationship between serum EC-SOD concentration and duration of diabetes (F = 5.31), carotid artery intimal-media thickness (F = 8.24), and severity of nephropathy (F = 16.05) and retinopathy (F = 4.43).

CONCLUSIONS

We observed a strong relationship between the serum concentration of EC-SOD and the severity of both micro- and macrovascular diabetic complications. These findings suggest that serum EC-SOD concentration levels may be a marker of vascular injury, possibly reflecting hyperglycemia-induced oxidative injury to the vascular endothelium and decreased binding of EC-SOD to the vascular wall.

Relationship between oxidative stress and extrinsic coagulation pathway in haemodialyzed patients

Enhanced oxidative stress (SOX), endothelial dysfunction and haemostatic abnormalities are common in end-stage renal failure patients undergoing maintenance haemodialysis (HD). We studied associations among circulating immunoreactive total lipid peroxides as a marker of short-time SOX, autoantibodies against oxidized LDL as a surrogate of prolonged SOX, copper/zinc superoxide dismutase (Cu/Zn SOD) as a major antioxidant enzyme, tissue factor (TF) as a principal initiator of extrinsic coagulation pathway counteracted by its inhibitor (TFPI), and prothrombin fragment 1+2 (F 1+2) as a surrogate of activated haemostasis.Pre-dialysis blood levels of all the markers studied were higher in 24 clinically stable HD patients compared to 11 healthy controls. Spearman's correlations among the three SOX markers were positive but nonsignificant in both HD patients and controls. In HD subjects, increased Cu/Zn SOD levels directly correlated with those of TF (rho=0.551, p=0.005) and TFPI (rho=0.501, p=0.001); the coagulation markers were also positively associated with each other (rho=0.663, p=0.0004). In healthy subjects, the relations between Cu/Zn SOD, TF and TFPI levels were inverse but not significant, and the direct association between TF and TFPI was nonsignificant either. In conclusion, increased plasma levels of Cu/Zn SOD, the antioxidant enzyme with emerging endothelial cell-protective and antithrombotic properties, may be a novel part of the system counteracting activated extrinsic coagulation system in maintenance HD patients.

Reduction in plasma total homocysteine through increasing folate intake in healthy individuals is not associated with changes in measures of antioxidant activity or oxidant damage

BACKGROUND

Various mechanisms have been proposed to explain the association between plasma total homocysteine (tHcy) and risk of cardiovascular disease, including oxidative activity of homocysteine.

OBJECTIVE

To explore the putative role of reactive oxygen species in the association between plasma tHcy and risk of cardiovascular disease in healthy individuals.

DESIGN

A double-blind, placebo-controlled crossover intervention to increase folate intake through diet (increased consumption of folate-rich foods) and supplement (400 micro g folic acid) was carried out in 126 healthy men and women. Measurements were made of antioxidant activity in red blood cells and plasma, and products of oxidant damage in plasma.

RESULTS

Diet and supplement-based interventions led to an increase in measures of folate status and a reduction in plasma tHcy. This was not associated with any significant change in measures of antioxidant activity (plasma and red blood cell glutathione peroxidase activity and red blood cell superoxide dismutase activity) or oxidant damage (plasma malondialdehyde), although an improvement in plasma total antioxidant capacity just failed to reach significance.

CONCLUSIONS

In healthy individuals lowering plasma tHcy does not have any functional implications regarding oxidative damage.

Genetic influence on cigarette-induced cardiovascular disease

Cigarette smoking as an addictive habit has accompanied human beings for more than 4 centuries. It is also one of the most potent and prevalent environmental health risks human beings are exposed to, and it is responsible for more than 1000 deaths each day in the United States. With recent research progress, it becomes clear that cigarette smoking can cause almost all major diseases prevalent today, such as cancer or heart disease. These detrimental effects are not only present in active smokers who choose the risk, but also to innocent bystanders, as passive smokers, who are exposed to cigarettes not-by-choice. While the cigarette-induced harm to human health is indiscriminate and severe, the degree of damage also varies from individual to individual. This intersubject variability in cigarette-induced pathologies is partly mediated by genetic variants of genes that may participate in detoxification process, eg, cytochrome P450 (CYP), cellular susceptibility to toxins, such as p53, or disease development. Through population studies, we have learned that certain CYP1A1 variants, such as Mspl polymorphism, may render the carriers more susceptible to cigarette-induced lung cancer or severe coronary atherosclerosis. The endothelial nitric oxide synthase intron 4 rare allele homozygotes are more likely to have myocardial infarction if they also smoke. In vitro experimental approach has further demonstrated that cigarettes may specifically regulate these genes in genotype-dependent fashion. While we still know little about genetic basis and molecular pathways for cigarette-induced pathological changes, understanding these mechanisms will be of great value in designing strategies to further reduce smoking in targeted populations, and to implement more effective measures in prevention and treatment of cigarette-induced diseases.

Relations between oxidative stress, hepatocyte growth factor, and liver disease in hemodialysis patients

BACKGROUND

Hepatocyte growth factor (HGF) and copper/zinc superoxide dismutase (Cu/Zn SOD) protect against tissue injury, including that due to oxidative stress (SOX). We studied whether they could be associated with each other, SOX markers, prevalence of viral hepatitis, and cardiovascular disease (CVD) and their laboratory surrogates in maintenance hemodialysis (HD) patients.

METHODS

In 24 patients, pre-dialysis serum HGF, plasma Cu/Zn SOD, total lipid peroxides, and serum autoantibodies against oxidized LDL were measured by ELISAs. Viral hepatitis B and C markers were determined by third generation microparticle ELISAs, and CVD was identified on a clinical basis.

RESULTS

In HD patients, circulating HGF, Cu/Zn SOD, and the other SOX markers were higher than in healthy controls, and HGF directly correlated with Cu/Zn SOD levels (P = 0.0006). Both HGF (P = 0.021) and Cu/Zn SOD (P=0.017) were positively associated with prevalence of viral hepatitis and serum alanine aminotransferase activity (P = 0.021 and P=0.040, respectively). Presence of CVD directly correlated with HGF (P = 0.001) but not with Cu/Zn SOD levels (P = 0.087). Circulating HGF positively related to serum C-reactive protein (P = 0.043). In patients without viral hepatitis and CVD, both HGF and Cu/Zn SOD were lower than in those with, and higher than in healthy controls. CVD (P = 0.003) and viral hepatitis (P = 0.024) were independent predictors of increased HGF, while positive viral hepatitis marker predicted increased Cu/Zn SOD levels (P = 0.019) in HD patients. There were no associations between HGF and the SOX markers in controls.

CONCLUSIONS

In maintenance HD patients, circulating Cu/Zn SOD and HGF levels are increased, likely as a part of the reparatory reaction against liver damage. Viral hepatitis status and liver function should be considered in further studies of Cu/Zn SOD in these subjects.

Relationship between physical activity and oxidative stress biomarkers in women

PURPOSE

To examine the relationship between physical activity and levels of plasma lipid peroxides, superoxide dismutase in erythrocytes (SOD), and glutathione peroxidase (GSH-Px) in whole blood activities.

METHODS

Cross-sectional study in 488 Spanish women. Two categories of leisure time physical activity were defined according to their intensity: low (<or=6 METs) and high (>6 METs). Energy expenditure in household activities was also recorded. Multivariate linear regression analyses were used to adjust for the effect of physical activity on lipid peroxides and SOD and GSH-Px for confounding variables.

RESULTS

The amount of leisure time physical activity was associated with high activity levels of SOD (P = 0.022) and GSH-Px (P = 0.002). Similar results were obtained when physical activity in household activities was added to total leisure physical activity. Physical activity of low intensity was associated with high SOD activity levels (P = 0.002) and that of high intensity with high GSH-Px activity levels (P = 0.001).

CONCLUSION

The amount and intensity of leisure physical activity were directly related to both antioxidant enzyme activity levels. The findings of this study suggest a modulatory effect of leisure physical activity intensity on antioxidative balance in the studied female population.

Nitric oxide and its decomposed derivatives decrease the binding of extracellular-superoxide dismutase to the endothelial cell surface

Extracellular-superoxide dismutase (EC-SOD) is bound to the vascular endothelial cell surface with an affinity for heparan sulfate proteoglycan. The binding of EC-SOD to the human umbilical vein endothelial cell (HUVEC) and bovine aortic endothelial cell surface proteoglycans was significantly decreased by the incubation with S-nitroso-N-acetyl-DL-penicillamine (SNAP) and +/- -N-[(E)-4-ethyl-2-[(Z)-hydroxyimino]-5-nitro-3-hexene-1-yl]-3-pyridine carboxamide (NOR4), potent nitric oxide (NO) donors. NO derived from lipopolysaccharide-stimulated J774 A-1 cells also decreased the binding of EC-SOD to HUVEC, and this decrease was blocked by N(G)-nitro-L-arginine, a nitric oxide synthase inhibitor. SNAP and NOR4 also decreased the binding of EC-SOD to immobilized heparin. Furthermore, the decomposed derivatives of NO donors and sodium nitrite decreased the binding of EC-SOD. These observations suggest that excess NO produced in the inflammatory conditions decreases the binding of EC-SOD to the vascular endothelial cell surface, which results in a loss of the ability to protect the endothelial cell surface from oxidative stress.

Lecithinized Cu, Zn-superoxide dismutase limits the infarct size following ischemia-reperfusion injury in rat hearts in vivo

Covalent binding of 4 molecules of phosphatidylcholine palmitoyl to human recombinant superoxide dismutase (SOD) results in a compound (lecithinized SOD) that has a longer half-life and greater affinity to the cell membrane than unmodified SOD. We investigated whether lecithinized SOD played a protective role against myocardial ischemia-reperfusion injuries in rats. Rats underwent 45 min of myocardial ischemia by occluding the left coronary artery followed by 120 min of reperfusion. They were randomly assigned to receive either lecithinized SOD, polyethylene glycol conjugated SOD (PEG-SOD), unmodified SOD, free lecithin derivative, or PBS intravenously at 5 min prior to reperfusion. Myocardial infarct area assessed by TTC staining was smaller in lecithinized SOD group than PEG-SOD, unmodified SOD, free lecithin derivative or control group. Blood pressure and heart rate was similar in each group. ELISA demonstrated SOD level in the heart was significantly high in lecithinized SOD group, especially in the heart of ischemia at risk. Although serum SOD level of PEG-SOD was as high as lecithinized SOD, SOD level of the heart was low. These data suggested lecithinized SOD had a protective effect in myocardial ischemia-reperfusion injuries through its increased bioavailability.

Overexpression of EC-SOD suppresses endothelial-cell-mediated LDL oxidation

Reactive oxygen species have been proposed to play important roles in atherosclerosis. To investigate the protective role of extracellular superoxide dismutase (EC-SOD), its inhibition of endothelial-cell-mediated LDL oxidation was examined. We constructed the recombinant adenovirus AxCAEC-SOD expressing human EC-SOD by CAG promoter. Infection of endothelial cells with AxCAEC-SOD resulted in EC-SOD protein secretion in a dose-dependent manner and a decrease of endothelial-cell-derived superoxide production. Moreover, it was proven to coexist with heparan sulfate by immunohistochemical staining. Endothelial-cell-mediated LDL oxidation enhanced by ferric-sodium EDTA was inhibited by 47% in TBARS formation by AxCAEC-SOD infection. In agarose gel electrophoresis, AxCAEC-SOD decreased the negative charge of oxidized LDL by 50% and suppressed fragmentation of apolipoprotein B. These results suggested that human EC-SOD localized in the extracellular space and reduced endothelial-cell-mediated LDL oxidation. In subendothelial space, EC-SOD bound on heparan sulfate might suppress LDL oxidation through reduction of superoxide anion.

Adverse effects of smoking in the renal patient

Smoking is a known risk factor for cardiovascular diseases, cancer, and several other health problems. It is the number one preventable cause of death in modern countries. The first evidence that smoking may be a renal risk factor was published in 1978. Since then, several studies documented that smoking is nephrotoxic in patients with diabetic and non-diabetic renal disease. Data from the Multiple Risk Factor Intervention Trial indicate that smoking even increases the renal risk in the general male population: an increased relative risk for end-stage renal failure (ESRF) was found for smokers as compared to non-smokers (up to 1.69 for heavy smokers). Several potential mechanisms of smoking-induced renal damage have been discussed, e.g. increase in blood pressure, alteration of intrarenal hemodynamics, as well as activation of the sympathetic nerve, the reninangiotensin and the endothelin systems. The pathomechanisms are, however, only partly understood. Once ESRF has become established, the failure to discontinue smoking adversely affects the prognosis of patients on renal replacement therapy, mainly by increasing the risk of cardiovascular complications. Discontinuation of smoking has been shown to improve both renal and cardiovascular prognosis in the renal patient and is probably the single most effective measure to retard progression of renal failure.

Antioxidant vitamins and enzymatic and synthetic oxygen-derived free radical scavengers in the prevention and treatment of cardiovascular disease

Oxygen-derived free radical formation can lead to cellular injury and death. Under normal situations, the human body has a free radical scavenger system (catalase, superoxide dismutase) that can detoxify free radicals. Antioxidant vitamins and enzymatic and synthetic oxygen-derived free radical scavengers have been used clinically to prevent the formation of oxidized LDL and to prevent reperfusion injury, which is often caused by free radicals. In this article, the pathogenesis of free radical production and cell injury are discussed, and therapeutic approaches for disease prevention are presented.

Effects of homocysteine on the binding of extracellular-superoxide dismutase to the endothelial cell surface

Homocysteine is known to be a risk factor for several vascular diseases. Previously, we found a significant association between plasma homocysteine and plasma extracellular-superoxide dismutase (EC-SOD) levels. The binding of EC-SOD to human and bovine aortic endothelial cell cultures showed significant decreases after incubation with 10 microM homocysteine, whereas the expression of EC-SOD in fibroblast cell cultures was inhibited with a high concentration (1 mM) of homocysteine. Furthermore, binding of EC-SOD to heparin immobilized on plates was decreased with homocysteine. These observations suggested that homocysteine decreases the binding of EC-SOD to vascular endothelial cell surfaces by degradation of endothelial heparan sulfate proteoglycan, which results in a loss of the ability to protect endothelial cell surfaces from oxidative stress.

Free radicals, cytokines and nitric oxide in cardiac failure and myocardial infarction

Myocardial infarction is the most common cause of congestive cardiac failure. Free radicals, cytokines, nitric oxide (NO) and antioxidants play a major role both in atherosclerosis and myocardial damage and preservation. In the early stages of atherosclerosis, neutrophils and monocytes infiltrate the intima and generate free radicals which damage the endothelial cells. As a result, production of NO and prostacyclin by the endothelial cells declines, which have cardioprotective actions. This also has relevance to the beneficial action of aspirin since, it can modulate both prostanoid and L-arginine-NO systems and NF-kB translocation. In both acute myocardial infarction and chronic congestive cardiac failure, the plasma levels of various inflammatory mediators such as interleukins and tumour necrosis factor-alpha (TNFalpha) are elevated. TNFalpha, produced by the inflammatory cells and the myocardium, can suppress myocardial contractility and induce the production of free radicals, which in turn can further damage the myocardium. Transforming growth factor beta (TGFbeta), polyunsaturated fatty acids and the glucose-insulin-potassium regimen can antagonize the harmful actions of TNFalpha and protect the myocardium. This explains why efforts made to reduce the levels of pro-inflammatory cytokines have beneficial action and preserve the myocardium.