Modulation of oxidant stress in vivo in chronic cigarette smokers

Systemic effects of smoking

Smoking is one of the major lifestyle factors influencing the health of human beings. Life-long cigarette smokers have a higher prevalence of common diseases such as atherosclerosis and COPD with significant systemic impact. The present review evaluates current knowledge concerning possible pathways through which cigarette smoking can affect human health, with special focus on extrapulmonary effects. Long-term smoke exposure can result in systemic oxidants-antioxidants imbalance as reflected by increased products of lipid peroxidation and depleted levels of antioxidants like vitamins A and C in plasma of smokers. A low-grade systemic inflammatory response is evident in smokers as confirmed by numerous population-based studies: elevated levels of C-reactive protein (CRP), fibrinogen, and interleukin-6, as well as increased counts of WBC have been reported. Furthermore, rheologic, coagulation and endothelial function markers like hematocrit, blood and/or plasma viscosity, fibrin d-dimer, circulating adhesion molecules (intracellular adhesion molecule-1, selectins), tissue plasminogen activator antigen, and plasminogen activator inhibitor type I are altered in chronic cigarette smokers. Although most of smoking-induced changes are reversible after quitting, some inflammatory mediators like CRP are still significantly raised in ex-smokers up to 10 to 20 years after quitting, suggesting ongoing low-grade inflammatory response persisting in former smokers. New longitudinal epidemiologic and genetic studies are required to evaluate the role of smoking itself and possible gene/environment interplay in initiation and development of smoking-induced common diseases affecting humans.

Quantitation of isoprostane isomers in human urine from smokers and nonsmokers by LC-MS/MS

A simple, rapid liquid chromatography-tandem mass spectrometry method was developed to identify and quantitate in human urine the isoprostanes iPF(2 alpha)-III, 15-epi-iPF(2 alpha)-III, iPF(2 alpha)-VI, and 8,12-iso-iPF(2 alpha)-VI along with the prostaglandin PGF(2 alpha) and 2,3-dinor-iPF(2 alpha)-III, a metabolite of iPF(2 alpha)-III. Assay specificity, linearity, precision, and accuracy met the required criteria for most analytes. The urine sample storage stability and standard solution stability were also tested. The methodology was applied to analyze 24 h urine samples collected from smokers and nonsmokers on controlled diets. The results for iPF(2 alpha)-III obtained by our method were significantly correlated with results by an ELISA, although an approximately 2-fold high bias was observed for the ELISA data. For iPF(2 alpha)-III and its metabolite 2,3-dinor-iPF(2 alpha)-III, smokers had significantly higher concentrations than nonsmokers (513 +/- 275 vs. 294 +/- 104 pg/mg creatinine; 3,030 +/- 1,546 vs. 2,046 +/- 836 pg/mg creatinine, respectively). The concentration of iPF(2 alpha)-VI tended to be higher in smokers than in nonsmokers; however, the increase was not statistically significant in this sample set. Concentrations of the other three isoprostane isomers showed no trends toward differences between smokers and nonsmokers. Among smokers, the daily output of two type VI isoprostanes showed a weak correlation with the amount of tobacco smoke exposure, as determined by urinary excretion of total nicotine equivalents.

Oxidative stress, chronic disease, and muscle wasting

Underlying the pathogenesis of chronic disease is the state of oxidative stress. Oxidative stress is an imbalance in oxidant and antioxidant levels. If an overproduction of oxidants overwhelms the antioxidant defenses, oxidative damage of cells, tissues, and organs ensues. In some cases, oxidative stress is assigned a causal role in disease pathogenesis, whereas in others the link is less certain. Along with underlying oxidative stress, chronic disease is often accompanied by muscle wasting. It has been hypothesized that catabolic programs leading to muscle wasting are mediated by oxidative stress. In cases where disease is localized to the muscle, this concept is easy to appreciate. Transmission of oxidative stress from diseased remote organs to skeletal muscle is thought to be mediated by humoral factors such as inflammatory cytokines. This review examines the relationship between oxidative stress, chronic disease, and muscle wasting, and the mechanisms by which oxidative stress acts as a catabolic signal.

The role of tobacco smoke induced mitochondrial damage in vascular dysfunction and atherosclerosis

The majority of individuals chronically exposed to tobacco smoke will eventually succumb to cardiovascular disease (CVD). However, despite the major cardiovascular health implications of tobacco smoke exposure, concepts of how such exposure specifically results in cardiovascular cell dysfunction that leads to CVD development are still being explored. Moreover, surprisingly little is known about the effects of prenatal and childhood tobacco smoke exposure on adult CVD development. Herein, it is proposed that the mitochondrion is a central target for environmental oxidants, including tobacco smoke. By virtue of its multiple, essential roles in cell function including energy production, oxidant signaling, apoptosis, immune response, and thermogenesis, damage to the mitochondrion will likely play an important role in the development of multiple common forms of human disease, including CVD. Specifically, this review will discuss the potential role of tobacco smoke and environmental oxidant exposure in the induction of mitochondrial damage which is related to CVD development. Furthermore, mechanisms of how mitochondrial damage can initiate and/or contribute to CVD are discussed, as are experimental results that are consistent with the hypothesis that mitochondrial damage and dysfunction will increase CVD susceptibility. Aspects of both adult and developmental (fetal and childhood) exposure to tobacco smoke on mitochondrial damage, function and disease development are also discussed, including the future implications and direction of studies involving the role of the mitochondrion in influencing disease susceptibility mediated by environmental factors.

Vitamin E supplementation and plasma 8-isoprostane and adiponectin in overweight subjects

OBJECTIVE

Isoprostanes are a marker of oxidant stress and atherosclerotic risk, and plasma concentrations are elevated in obesity. Adiponectin is a regulator of insulin sensitivity, and low circulating levels are associated with oxidant stress and obesity. The aim of this study was to determine the effect of vitamin E supplementation on plasma concentrations of 8-isoprostane and adiponectin in overweight/obese subjects.

RESEARCH METHODS AND PROCEDURES

The study was a 6-month, randomized, double-blind, placebo-controlled trial in 80 overweight subjects (60 women and 20 men, BMI >27 kg/m(2)). Exclusion criteria were serious illness, smoking, or taking antioxidant supplements. Participants were randomized to receive 800 IU/d natural vitamin E (n = 39) or placebo (n = 41) for 3 months with an increase in the dose to 1200 IU/d for a further 3 months. Plasma 8-isoprostane and adiponectin concentrations were measured at baseline and 3 and 6 months.

RESULTS

During 6 months of supplementation with vitamin E, plasma vitamin E concentration increased significantly (p < 0.001) by 76%, and plasma 8-isoprostane concentrations decreased significantly (-11%, p = 0.03), whereas plasma adiponectin concentrations did not change significantly.

DISCUSSION

These findings suggest that supplementation with high-dose vitamin E decreases systemic oxidative stress and 8-isoprostane concentrations in overweight/obese individuals. A decrease in plasma 8-isoprostane has the potential to reduce risk of cardiovascular disease in obesity.

Pyridoxamine analogues scavenge lipid-derived gamma-ketoaldehydes and protect against H2O2-mediated cytotoxicity

Isoketals and levuglandins are highly reactive gamma-ketoaldehydes formed by oxygenation of arachidonic acid in settings of oxidative injury and cyclooxygenase activation, respectively. These compounds rapidly adduct to proteins via lysyl residues, which can alter protein structure/function. We examined whether pyridoxamine, which has been shown to scavenge alpha-ketoaldehydes formed by carbohydrate or lipid peroxidation, could also effectively protect proteins from the more reactive gamma-ketoaldehydes. Pyridoxamine prevented adduction of ovalbumin and also prevented inhibition of RNase A and glutathione reductase activity by the synthetic gamma-ketoaldehyde, 15-E2-isoketal. We identified the major products of the reaction of pyridoxamine with the 15-E2-isoketal, including a stable lactam adduct. Two lipophilic analogues of pyridoxamine, salicylamine and 5'-O-pentylpyridoxamine, also formed lactam adducts when reacted with 15-E2-isoketal. When we oxidized arachidonic acid in the presence of pyridoxamine or its analogues, pyridoxamine-isoketal adducts were found in significantly greater abundance than the pyridoxamine-N-acyl adducts formed by alpha-ketoaldehyde scavenging. Therefore, pyridoxamine and its analogues appear to preferentially scavenge gamma-ketoaldehydes. Both pyridoxamine and its lipophilic analogues inhibited the formation of lysyl-levuglandin adducts in platelets activated ex vivo with arachidonic acid. The two lipophilic pyridoxamine analogues provided significant protection against H2O2-mediated cytotoxicity in HepG2 cells. These results demonstrate the utility of pyridoxamine and lipophilic pyridoxamine analogues to assess the potential contributions of isoketals and levuglandins in oxidant injury and inflammation and suggest their potential utility as pharmaceutical agents in these conditions.

Elevated circulating levels of markers of oxidative-nitrative stress and inflammation in a genetic rat model of metabolic syndrome

Metabolic syndrome is a cluster of metabolic diseases that in essence greatly promotes progression of atherosclerosis. We used a genetic model of the metabolic syndrome, the SHR/NDmcr-cp (SHR/cp) rat, from 6 to 40 weeks of age to investigate whether systemic oxidative stress, a major cause of atherosclerosis, increases in this syndrome. Nine-week-old male rats already showed manifestations of metabolic syndrome, including heavier body weight, higher blood pressure and higher levels of serum glucose, insulin and various lipids compared to the age-matched Wistar Kyoto (WKY) rats used as a genetic control. These metabolic parameters gradually progressed with age. Likewise, the serum levels of oxidative stress markers, including lipid peroxides, which oxidatively modify low-density lipoprotein (LDL) and 8-hydroxydeoxyguanosine (8-OHdG), gradually increased in SHR/cp rats. The serum levels of 3-nitrotyrosine and 3-chlorotyrosine also persistently increased, indicating the involvement of peroxynitrite or myeloperoxidase-catalyzed oxidation. In addition, high-sensitivity C-reactive protein (hsCRP), an early marker of inflammation, temporarily increased in SHR/cp rats compared to WKY rats. These findings suggest that oxidative stress, as well as nitrative stress and inflammation, increases in the metabolic syndrome, which may contribute to the development of atherosclerosis.

Relationship between urinary 15-F2t-isoprostane and 8-oxodeoxyguanosine levels and breast cancer risk

To evaluate the role of oxidative stress in breast cancer, we measured urinary levels of 15-F(2t)-isoprostane (15-F(2t)-IsoP) and 8-oxodeoxyguanosine (8-oxodG) in 400 cases and 401 controls, participants of the Long Island Breast Cancer Study Project. We also analyzed the effect of different factors that are associated with oxidative stress and might influence 15-F(2t)-IsoP and 8-oxodG levels. We observed a statistically significant trend in breast cancer risk with increasing quartiles of 15-F(2t)-IsoP levels [odds ratio (OR), 1.25; 95% confidence interval (95% CI), 0.81-1.94; OR, 1.53; 95% CI, 0.99-2.35; OR, 1.88; 95% CI, 1.23-2.88, for the 2nd, 3rd, and 4th quartile relative to the lowest quartile, respectively; P(trend) = 0.002]. Although it is possible that increased levels may reflect the stress associated with recent treatment, the positive association was also observed when the analyses were restricted to case women for whom chemotherapy and radiation therapy had not yet been initiated at the time of the urine collection. The association with the highest quartile compared with lowest quartile of 15-F(2t)-IsoP was similar across strata of age, physical activity, fruit and vegetable intake, alcohol intake, cigarette smoking, body mass index, and menopausal status. We did not observe any association of breast cancer risk with 8-oxodG levels, but when cases with radiation treatment were removed from the analysis, a significant inverse trend (P = 0.04) was observed. Among controls, levels of 15-F(2t)-IsoP were higher among current cigarette smokers but did not differ by the amount of physical activity, fruit and vegetable intake, alcohol intake, body mass index, and menopausal status. Among controls, levels of 8-oxodG were higher among postmenopausal women and current and former cigarette smokers but did not differ by the other factors. In summary, our results suggest that urinary markers of lipid peroxidation and oxidative DNA damage may be associated with breast cancer risk.

Uric acid restores endothelial function in patients with type 1 diabetes and regular smokers

Endothelial dysfunction is a characteristic finding in both patients with type 1 diabetes and in regular smokers and is an important precursor to atherosclerosis. The urate molecule has antioxidant properties, which could influence endothelial function. The impact of acutely raising uric acid concentrations on endothelial function was studied in eight men with type 1 diabetes, eight healthy regular smokers, and eight age-matched healthy control subjects in a randomized, four-way, double-blind, placebo-controlled study. Subjects received 1,000 mg uric acid i.v. in vehicle, 1,000 mg vitamin C as a control antioxidant, vehicle alone, or 0.9% saline on separate occasions over 1 h. Forearm blood flow responses to intrabrachial acetylcholine and sodium nitroprusside were assessed using venous occlusion plethysmography. Responses to acetylcholine, but not sodium nitroprusside, were impaired in patients with diabetes (P < 0.001) and in smokers (P < 0.005) compared with control subjects. Administration of uric acid and vitamin C selectively improved acetylcholine responses in patients with type 1 diabetes (P < 0.01) and in regular smokers (P < 0.05). Uric acid administration improved endothelial function in the forearm vascular bed of patients with type 1 diabetes and smokers, suggesting that high uric acid concentrations in vivo might serve a protective role in these and other conditions associated with increased cardiovascular risk.

Cardiovascular pharmacology and physiology of the isoprostanes

F(2)-isoprostanes are a complex family of compounds produced from arachidonic acid via a free radical-catalyzed mechanism. Their quantification as a pathophysiological biomarker provides a unique opportunity to investigate lipid peroxidation in vascular diseases. Their measurement also provides an interesting biomarker for the rational dose selection of antioxidants in vascular diseases where oxidative stress might be involved. In addition to their use as biomarkers, some isoprostanes possess a biological activity. The 15-series F(2)- and E(2)-isoprostanes mediate vasoconstriction in different vascular beds and species. In addition, 15-F(2t)-IsoP induces smooth muscle cells mitogenesis and monocyte adhesion to endothelial cells. The data available supports but does not prove the hypothesis that isoprostanes are involved in vascular physiology and pathogenesis.

Improved method of plasma 8-Isoprostane measurement and association analyses with habitual drinking and smoking

AIM: To develop a simple and accurate method for quantifying 8-isoprostane in plasma by employing a combination of two-step solid-phase extraction of samples and a commercially available ELISA kit, and by this method to examine the effects of drinking and smoking habits against the levels of plasma 8-isoprostane in healthy Japanese volunteers.

METHODS: Plasma 8-isoprostane was extracted with ODS gel suspension followed by NH₂ Sep-Pak column. The 8-isoprostane fractions were assayed using a commercially available ELISA kit. We measured plasma 8-isoprostane levels in 157 healthy Japanese volunteers divided into three groups (64 non-habitual drinkers, 56 moderate drinkers and 37 habitual drinkers) according to their alcohol consumption per week. Genotypes of aldehyde dehydrogenase 2 (ALDH2) were also determined to investigate the plasma 8-isoprostane levels with reference to drinking habits. In addition, the plasma 8-isoprostane levels of 96 non-smokers and 61 smokers from the same subjects were compared.

RESULTS: Our method fulfilled all the requirements for use in routine clinical assays with respect to sensitivity, intra- and inter-assay reproducibility, accuracy and dynamic assay range. Significant increases of plasma 8-isoprostane levels were observed in female habitual drinkers when compared with those of non-habitual drinkers (t = 5.494, P < 0.0001) as well as moderate drinkers (t = 3.542, P < 0.005), and 8-isoprostane levels were also significantly different between ALDH2*2/1 and ALDH2*1/1 in the female habitual drinkers (t = 6.930, P < 0.0001), suggesting that excessive drinking of alcohol may increase oxidization stress, especially in females. On the contrary, no significant difference of the plasma 8-isoprostane levels was observed between non-smokers and smokers.

CONCLUSION: Our present method was proved to be a simple and accurate tool for measuring plasma 8-isoprostane. However, the clinical utility of plasma 8-isoprostane for drinking and smoking habits was limited since elevated 8-isoprostane levels were observed in female heavy drinkers, and no association was found between smokers and nonsmokers.

Measures of Oxidative Stress

Development of in vivo markers of oxidative stress that are sensitive, specific, reliable, and accurate in reflecting underlying atherosclerotic disease states and prediction of cardiovascular risk and clinical events will be invaluable in the future in clinical medicine. Oxidized low-density lipoprotein (OxLDL) and isoprostanes are emerging plasma biomarkers that hold promise for cardiovascular risk prediction. This article describes the pathophysiology of OxLDL and isoprostanes as potential biomarkers, the rationale behind development of methods to measure OxLDL and isoprostanes, and a detailed description of current methodologies, including advantages and disadvantages of available assays. Clinical investigations consisting of epidemiological, case-control, and prospective studies are reviewed to elucidate the role of these biomarkers in reflecting pathophysiology and risk prediction.

Increased free malondialdehyde concentrations in smokers normalise with a mixed fruit and vegetable juice concentrate: a pilot study

BACKGROUND

Cigarette smoking, a cardiovascular risk factor leading to oxygen free radical formation, is involved in the development of serious pathological conditions. On the other hand, a healthy diet and adequate supplementation can help prevent many diseases. The aim of our study was to evaluate in healthy light smokers the effects of supplementation with mixed fruit and vegetable juice powder concentrate on homocysteine metabolism and oxidative status.

METHODS

In this pilot study, 32 healthy volunteers, 16 light smokers and 16 non-smokers, on twice daily supplementation were monitored at time zero and after 30 days. Plasma homocysteine, and serum vitamin B(12) and folate concentrations were measured by immunoenzymatic assays; reactive oxygen species, total antioxidant capacity and thiol groups by spectrophotometric methods; and total and free malondialdehyde concentrations by gas chromatography-mass spectrometry with isotopic dilution.

RESULTS

Baseline free malondialdehyde concentrations were significantly higher in smokers than in non-smokers and normalised after 30-day supplementation. Baseline results for all the other parameters remained unchanged after supplementation, with no significant differences between smokers and non-smokers.

CONCLUSION

This is the first study showing a significant decrease in free malondialdehyde levels in light smokers after 1-month phytonutrient supplementation.

Cigarette smokers differ in their handling of natural (RRR) and synthetic (all rac) alpha-tocopherol: a biokinetic study in apoE4 male subjects

We have compared the biokinetics of deuterated natural (RRR) and synthetic (all rac) alpha-tocopherol in male apoE4-carrying smokers and nonsmokers. In a randomized, crossover study subjects underwent two 4-week treatments (400 mg/day) with undeuterated RRR- and all rac-alpha-tocopheryl acetate around a 12-week washout. Before and after each supplementation period subjects underwent a biokinetic protocol (48 h) with 150 mg deuterated RRR- or all rac-alpha-tocopheryl acetate. During the biokinetic protocols, the elimination of endogenous plasma alpha-tocopherol was significantly faster in smokers (P < 0.05). However, smokers had a lower uptake of deuterated RRR than nonsmokers, but there was no difference in uptake of deuterated all rac. The supplementation regimes significantly raised plasma alpha-tocopherol (P < 0.001) with no differences in response between smokers and nonsmokers or between alpha-tocopherol forms. Smokers had significantly lower excretion of alpha-carboxyethyl-hydroxychroman than nonsmokers following supplementation (P < 0.05). Nonsmokers excreted more alpha-carboxyethyl-hydroxychroman following RRR than all rac; however, smokers did not differ in excretion between forms. At baseline, smokers had significantly lower ascorbate (P < 0.01) and higher F(2)-isoprostanes (P < 0.05). F(2)-isoprostanes in smokers remained unchanged during the study, but increased in nonsmokers following alpha-tocopherol supplementation. These data suggest that apoE4-carrying smokers and nonsmokers differ in their handling of natural and synthetic alpha-tocopherol.

Vitamin C fails to protect amino acids and lipids from oxidation during acute inflammation

The observation that antioxidant vitamins fail to confer protective benefits in large, well-designed randomized clinical trials has led many to question the role of oxidative stress in the pathogenesis of disease. However, there is little evidence that proposed antioxidants actually scavenge reactive intermediates in vivo. Ascorbate reacts rapidly with oxidants produced by activated neutrophils in vitro, and neutrophils markedly increase their oxidant production when mice are infected intraperitoneally with the gram-negative bacterium Klebsiella pneumoniae. To explore the antioxidant properties of ascorbate in vivo, we therefore used K. pneumoniae infection as a model of oxidative stress. When mice deficient in L-gulono-gamma-lactone oxidase (Gulo(-/-)), the rate-limiting enzyme in ascorbate synthesis, were depleted of ascorbate and infected with K. pneumoniae, they were three times as likely as ascorbate-replete Gulo(-/-)mice to die from infection. Mass spectrometric analysis of peritoneal lavage fluid revealed a marked increase in the levels of oxidized amino acids and of F2-isoprostanes (sensitive and specific markers of lipid oxidation) in infected animals. Surprisingly, there were no significant differences in the levels of the oxidation products in the ascorbate-deficient and -replete Gulo(-/-)mice. Our observations suggest that ascorbate plays a previously unappreciated role in host defense mechanisms against invading pathogens but that the vitamin does not protect amino acids and lipids from oxidative damage during acute inflammation. To examine the oxidation hypothesis of disease, optimal antioxidant regimens that block oxidative reactions in animals and humans need to be identified.

Alcohol consumption is directly associated with circulating oxidized low-density lipoprotein

Findings on the association of alcohol consumption and oxidation of low-density lipoprotein (LDL), which is thought to play a crucial role in the generation of atherosclerotic lesion, are inconsistent. The aim of the present study was to investigate the association of total alcohol consumption and type of alcoholic beverage with circulating plasma LDL oxidation. This cross-sectional study included data of circulating oxidized LDL (ox-LDL) from a subpopulation of 587 men and women enrolled in a population-based survey conducted in 2000 in Girona (Spain). Multivariate analysis was performed to describe the independent association of alcohol consumption and ox-LDL. Increasing alcohol consumption was associated with high in vivo ox-LDL levels in the present population. The consumption of 10 g of alcohol was associated with an increase of 2.40 U/L of ox-LDL (p = 0.002). Adjustment for dietary variables, leisure-time physical activity, educational level, smoking, LDL-cholesterol, high-density lipoprotein-cholesterol, glycemia, triglycerides, diabetes, body mass index, waist circumference, and systolic and diastolic blood pressures only slightly modified this association (p = 0.003). In this full adjusted model the consumption of 10 g of alcohol per day was associated with an increase of 2.11 U/L of ox-LDL. Consumption of wine (ml/day) was associated with increasing ox-LDL levels (p = 0.029), however, attenuated after controlling for alcohol. No significant relationship of ox-LDL with alcohol-independent consumption of wine, beer, and spirits was observed. Alcohol consumption was independently and directly associated with circulating ox-LDL in the present population.

F2-isoprostanes as markers of oxidative stress in vivo: an overview

The isoprostanes are a unique series of prostaglandin-like compounds formed in vivo via a non-enzymatic mechanism involving the free radical-initiated peroxidation of arachidonic acid. This article summarizes selected aspects regarding current knowledge of these compounds and their value as markers of oxidative injury. Novel aspects related to the biochemistry of isoprostane formation are discussed and methods by which these compounds can be analysed and quantified are summarized. A considerable portion of this article examines the utility of F(2)-isoprostanes as markers of oxidant injury in vivo. Numerous studies carried out over the past decade have shown that these compounds are extremely accurate measures of lipid peroxidation and have illuminated the role of oxidant injury in a number of human diseases including atherosclerosis, Alzheimer's disease and pulmonary disorders.

An approach to the validation of biomarkers of harm for use in a tobacco context

There is both a call and a need for biomarkers of harm that are validated for use in a tobacco context. Currently, there are no validated biomarkers and there is no consensus about which ones may be suitable for this purpose. To advance the science in this area a working definition of biomarkers of harm and a shortlist of candidate biomarkers are proposed. A framework for the validation of biomarkers of harm using of a series of epidemiological studies culminating in a targeted prospective study is outlined. The candidate biomarkers have advanced to preliminary testing although this does not imply that any on the shortlist will become validated. This framework could also be used for the evaluation of proteomic, genomic, transcriptosomic or metabonomic profiles, which may turn out to be the preferred biomarkers for use in harm prediction. Biomarker studies would complement data that are generated from specific in vitro tests and from animal studies to evaluate tobacco products.

Oxidative damage and platelet activation as new predictors of mobility disability and mortality in elders

Mobility disability is an early phase of the disablement process in older adults, and represents a major risk factor for physical disability and mortality. Pathophysiological mechanisms responsible for the onset of mobility limitation are still largely unknown. Oxidative damage, responsible for the disruption of the equilibrium of biological systems by damaging major constituent molecules, might play an important role in the pathway leading to major health-related events. It has been suggested the existence of a vicious cycle involving oxidative damage, platelet activation, and inflammation as promoter of pathophysiological changes occurring with aging. This hypothesis is based on the following observations: (a) oxidative damage is associated with diseases and clinical conditions potentially leading to disability and mortality; (b) oxidative damage is associated with platelet activation, and a vicious cycle involving oxidative damage, platelet activation, and inflammation has been demonstrated in several metabolic disorders potentially leading to mobility disability; (c) the age-related physical decline may be associated to the oxidative damage due to the excess of free radicals; (d) antioxidant defense and behavioral factors (e.g., physical activity, dietary restriction, smoking cessation) play an important role in the reduction of oxidative damage levels and are associated with improved physical performance and muscle strength.

Aspirin resistance

Aspirin resistance is the inability of aspirin to reduce platelet production of thromboxane A2 and thereby platelet activation and aggregation. Increasing degrees of aspirin resistance may correlate independently with increasing risk of cardiovascular events. Aspirin resistance can be detected by laboratory tests of platelet thromboxane A2 production or platelet function that depend on platelet thromboxane production. Potential causes of aspirin resistance include inadequate dose, drug interactions, genetic polymorphisms of COX-1 and other genes involved in thromboxane biosynthesis, upregulation of non-platelet sources of thromboxane biosynthesis, and increased platelet turnover. Aspirin resistance can be overcome by treating the cause or causes, and reduced by minimising thromboxane production and activity, and blocking other pathways of platelet activation. Future research is aimed at defining aspirin resistance, developing reliable tests for it, and establishing the risk of associated cardiovascular events. Potential mechanisms of aspirin resistance can then be explored and treatments assessed.

Oxidative stress in asthma and COPD: antioxidants as a therapeutic strategy

Asthma and chronic obstructive pulmonary disease (COPD) are inflammatory lung diseases that are characterized by systemic and chronic localized inflammation and oxidative stress. Sources of oxidative stress arise from the increased burden of inhaled oxidants, as well as elevated amounts of reactive oxygen species (ROS) released from inflammatory cells. Increased levels of ROS, either directly or via the formation of lipid peroxidation products, may play a role in enhancing the inflammatory response in both asthma and COPD. Moreover, in COPD it is now recognized as the main pathogenic factor for driving disease progression and increasing severity. ROS and lipid peroxidation products can influence the inflammatory response at many levels through its impact on signal transduction mechanisms, activation of redox-sensitive transcriptions factors, and chromatin regulation resulting in pro-inflammatory gene expression. It is this impact of ROS on chromatin regulation by reducing the activity of the transcriptional co-repressor, histone deacetylase-2 (HDAC-2), that leads to the poor efficacy of corticosteroids in COPD, severe asthma, and smoking asthmatics. Thus, the presence of oxidative stress has important consequences for the pathogenesis, severity, and treatment of asthma and COPD. However, for ROS to have such an impact, it must first overcome a variety of antioxidant defenses. It is likely, therefore, that a combination of antioxidants may be effective in the treatment of asthma and COPD. Various approaches to enhance the lung antioxidant screen and clinical trials of antioxidant compounds are discussed.

Isoprostanes and Oxidative Stress in Off-Pump and On-Pump Coronary Bypass Surgery

BACKGROUND

Conventional on-pump coronary artery bypass grafting (CABG) is associated with a systemic inflammatory response and by an increased production of reactive oxygen species, whereas off-pump coronary artery bypass grafting (OPCAB) is thought to be accompanied by less oxidative stress. Urinary isoprostane iPF2alpha-III is a new marker reflecting oxidative stress; it has emerged as the most reliable marker of oxidative stress status in vivo. This study was designed to ascertain whether OPCAB compared with CABG represents a surgical strategy that avoids oxidative stress. To this end urinary isoprostanes and other established oxidative stress markers were measured during the first 24 hours after CABG and OPCAB.

METHODS

Fifty low-risk coronary patients were randomly assigned to CABG or OPCAB. Urinary isoprostane iPF2alpha-III levels, plasma levels of free malondialdehyde, and total antioxidant status were measured before, during, and up to 24 hours after surgery.

RESULTS

In OPCAB iPF2alpha-III excretion remained unchanged throughout the study. As expected, in CABG iPF2alpha-III levels significantly increased during surgery and returned at baseline 24 hours later. Free malondialdehyde behaved similarly, with no change in OPCAB and sharp increases during CABG. Conversely, total antioxidant status showed a sharp drop during CABG, followed by a slow recovery, whereas a significantly lower drop occurred in OPCAB.

CONCLUSIONS

In this randomized study in low-risk coronary patients, OPCAB revealed less perioperative oxidative stress, as reflected by lack of excretion of iPF2alpha-III in urine, by lack of increase of plasma free malondialdehyde, and by lower decreases in plasma total antioxidant status.

Oxidative stress and diabetic cardiovascular complications

Diabetes diagnoses are increasing at an alarming rate worldwide. The majority of diabetes-related deaths arise from cardiovascular complications such as myocardial infarction, stroke, and peripheral vascular disease. Oxidative stress has been demonstrated to be present in animal models as well as in patients with diabetes and has been suggested as a possible contributor to the accelerated atherosclerosis seen in diabetics. The generation of reactive oxygen species in diabetes occurs via several mechanisms and is initiated not only by glucose, but also by other substances that are found at elevated levels in diabetic patients. The resulting oxidative stress leads to a number of proatherogenic events. The elucidation of the mechanisms of oxidative stress in diabetes and their relationship with atherosclerosis could potentially identify molecular targets of therapy for this condition and its cardiovascular consequences.

Benefits of prolonged gradient separation for high-performance liquid chromatography-tandem mass spectrometry quantitation of plasma total 15-series F-isoprostanes

The F(2)-isoprostanes are products of free-radical-induced oxidation of arachidonic acid (AA) that are stereoisomers of prostaglandin F(2alpha) (PGF(2alpha)). We describe a method for quantitation of several 15-series PGF isomers (15-PGFs) and AA by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS). Plasma samples were subjected to alkaline hydrolysis and acidified, and total (free + esterified) 15-PGFs and AA were extracted with organic solvents. The analytes were separated by gradient reverse-phase HPLC and detected by multiple reaction monitoring on a triple-quadrupole mass spectrometer, using deuterated internal standards for quantitation. The assay had a linear range of 1-40 pg of 8-iso-PGF(2alpha) on column and can quantify as little as 40 pg/mL (0.11 nM) in plasma. Outcomes significantly correlated (p < 0.0001) with data obtained by gas chromatography-mass spectrometry GC-MS or enzyme-linked immunosorbent assay. All plasma 15-PGF isomers increased over time with in vitro cigarette smoke exposure and correlated (p < 0.0001) with each other. The same strong inter-15-PGF correlations were observed in plasma from healthy young adult subjects. The coefficients of variation of HPLC-MS-MS measurements (24-32%) were smaller than those obtained by GC-MS (53%). Thus, HPLC-MS-MS potentially offers greater precision and allows quantitation of more compounds with simpler sample preparation than existing methods. Ours is the first validated quantitative assay using HPLC-tandem MS applied to plasma total 15-PGFs.

Salivary isoprostanes indicate increased oxidation injury in periodontitis with additional tobacco abuse

Isoprostanes (IPs) are indicators of in-vivo oxidative stress, and have been successfully used as markers for chronic inflammatory processes. The presence of chronic periodontal disease and cigarette smoking has been individually linked to the development of atherosclerosis, yet data regarding oxidative stress in this context are not available yet. The aim of this study was to evaluate levels of the salivary prostaglandins (PGs) 8-epi-PGF(2alpha), 6-oxo-PGF(1alpha), thromboxane B(2) (TXB(2)) and PGF(2alpha) in association with periodontal disease status with and without additional cigarette smoking. We analyzed saliva samples from 121 adults, (aged 21-73 years, 90 non-smokers, 31 smokers) for levels of 8-epi-PGF(2alpha), 6-oxo-PGF(1alpha), TXB(2) and PGF(2alpha). On the basis of periodontal disease indices the periodontal status of each subject was assessed and outcomes were then correlated with smoking status and laboratory findings. Salivary 8-epi-PGF(2alpha) levels increased with deteriorating plaque index, and were significantly higher (115.5 +/- 23.5 pg/ml) in smoking individuals, when compared to non-smokers (70.2 +/- 20.4 pg/ml, p<0.0001). In addition, smokers showed higher TXB(2) and PGF(2alphas) and lower 6-oxo-PGF(1alpha) levels p<0.0001). Oxidative stress, as reflected by elevated salivary 8-epi-PGF(2alpha) levels, is associated with the extent of periodontal disease and is significantly aggravated by concomitant tobacco abuse. Chronic inflammation and smoking have been individually associated with the development of atherosclerosis. The results of this study indicate that: 1) salivary IPs can reliably assess the degree of oxidative stress, and: 2) smoking and periodontal disease are two modifiable cardiovascular risk factors, able to potentiate each other.

Urinary 8-isoprostaglandin F(2alpha) level in Behçet's disease

Although its etiology remains unknown, the increased production of reactive oxygen species in Behçet's disease (BD) have been reported. Furthermore, it has been suggested that vascular and endothelial tissue damage seen in BD is related to elevated reactive oxygen species generated by activated neutrophils from BD patients. To investigate the formation of lipid peroxidation in BD patients in vivo, urinary level of 8-isoprostaglandin F(2alpha) was quantitated by enzyme immunoassay after solid phase extraction in different clinical forms of BD patients. There was no difference in urinary level of 8-isoprostaglandin F(2alpha) between BD patient and healthy control group. There was also no difference in urinary levels of 8-isoprostaglandin F(2alpha) in subgroup analyses of BD patients, i.e. in mucocutaneous and vascular type BD patients; active and inactive BD patients. Contrary to the findings in literature, we found no difference in urinary level of 8-isoprostaglandin F(2alpha) between patients with systemic lupus erythematosus and healthy control group. These findings show no increase in lipid peroxidation despite the augmented formation of reactive oxygen species in BD patients. It may be interesting to assess formation of urinary level of 8-isoprostaglandin F(2alpha) in BD patients who do not take any medication.

Oxidant injury occurs rapidly after cardiac arrest, cardiopulmonary resuscitation, and reperfusion

OBJECTIVE

Investigations conducted in cellular models show that reperfusion of ischemic tissue is associated with a burst of reactive oxidant species within minutes after reperfusion. Oxidant injury may play a role in the poor outcome typical of people resuscitated from cardiac arrest. The objective of the present study was to determine the presence and timing of oxidant injury in an in vivo model of cardiac arrest.

DESIGN

Randomized controlled.

SETTING

University medical center laboratory.

SUBJECTS

Domestic swine.

INTERVENTIONS

We evaluated oxidant injury during and after 8 mins of cardiac arrest using a gas chromatography/mass spectrometry F2-isoprostane assay and compared these results with a matched control group.

MEASUREMENTS AND MAIN RESULTS

Baseline mean arterial, venous, and brain tissue F2-isoprostane levels were not significantly different when the cardiac arrest group was compared with the control group. However, in the group subjected to cardiac arrest and cardiopulmonary resuscitation we found significant (p < .0006) two- to three-fold increases in venous and arterial F2-isoprostane levels, which peaked between 15 and 30 mins after reperfusion and returned to baseline within 90 mins (p < .0006). Overall mean (+/- SE) brain tissue F2-isoprostane levels increased significantly to 370 +/- 60 vs. 140 +/- 60 ng/g tissue in the cardiac arrest group compared with the control group (p = .026).

CONCLUSION

This study shows that F2-isoprostane measurement could be used to assess oxidant injury in an animal model of cardiac arrest and that oxidant injury occurs rapidly after cardiac arrest and reperfusion.

Green Tea Consumption and Serum Malondialdehyde-Modified LDL Concentrations in Healthy Subjects

OBJECTIVE

Green tea was shown to inhibit LDL oxidation, platelet aggregation, and matrix metalloproteinases (MMPs) activities in vitro. We tried to elucidate whether or not green tea consumption may have these effects in vivo, which may be protective against atherosclerotic disease.

METHODS

We measured serum malondialdehyde-modified LDL (MDA-LDL) concentrations and urine 8-epi-prostaglandin (PG) F(2alpha) in 22 healthy male nonsmokers. They drank 7 cups/day of water for 2 weeks and drank 7 cups/day of green tea for the next 2 weeks. Regarding platelet aggregation, plasma thromboxane B(2) (TXB(2)) and 6-keto-PGF(1alpha) concentrations and ex vivo platelet aggregation were evaluated. Plasma MMP-2 and -9 concentrations were also measured.

RESULTS

Of the 22 subjects, 20 had been in the habit of drinking green tea before the study. Plasma catechins concentrations significantly decreased at the end of the water period and then increased at the end of the green tea period. Although no change in plasma LDL-cholesterol concentrations (110 +/- 33 vs. 113 +/- 28 mg/dL, p = NS) was found, MDA-LDL concentrations (84 +/- 45 vs. 76 +/- 40 IU/L, p < 0.05) and the ratio of MDA-LDL/LDL-cholesterol (0.74 +/- 0.21 vs. 0.65 +/- 0.20, p < 0.02) significantly decreased at the end of the green tea period. However, no significant changes were observed in urine 8-epi-PGF(2alpha) concentrations, in platelet aggregation, nor in plasma TXB(2), 6-keto-PGF(1alpha) or MMP concentrations.

CONCLUSION

Daily consumption of green tea decreased serum MDA-LDL concentrations, but it had no significant effects on platelet aggregation, platelet TX production or plasma MMPs concentrations. Our results suggest that green tea consumption may inhibit LDL oxidation in vivo.

Passive cigarette smoking increases isoprostane formation

Passive smoking has been demonstrated to exert a variety of deleterious effects eventually resulting in vascular damage. Isoprostanes, a reliable marker of in vivo oxidation injury, have been shown to increase in active cigarette smoking. Data for passive smoking are lacking. We were examining the isoprostane 8-epi-PGF2alpha in 12 smokers and non-smokers exposed daily to passive cigarette smoke for 12 days. Plasma samples stored at liquid nitrogen from people having been examined earlier were used. Prevalues of 8-epi-PGF2alpha are higher in cigarette smokers. Exposure to passive smoking causes a significant increase in 8-epi-PGF2alpha in non-smokers, while in smokers there is only a trendwise increase. After repeated passive smoke exposure, 8-epi-PGF2alpha in non-smokers approaches the respective values of smokers. There is a significant correlation of 8-epi-PGF2alpha to the thromboxane (plasma, serum, conversion from exogenous precursor, 11-dehydro-TXB2) parameters (MDA, HHT- conversion) examined in these patients before. The findings document a significant temporary increase in in vivo oxidation injury due to passive smoke favouring development and/or progression of vascular disease.

Effects of vitamin E on the toxicity of oxidized LDL on endothelial cells in vitro in smokers vs nonsmokers on diets rich in fish

OBJECTIVE

To clarify whether supplementation of vitamin E can alter the low density lipoprotein (LDL) oxidation properties and thereby affect endothelial cell function and prostacyclin production in smokers compared to nonsmokers on diets rich in fish in a pilot study.

DESIGN

The LDL of six smokers and six nonsmokers on habitual high fish diet was isolated before and after an 8-week supplementation of vitamin E (800 IU/day). LDL was oxidized by incubation with CuSO4. Cytotoxicity of LDL oxidized to different degrees on endothelial cells was investigated in vitro in these two groups.

SETTING

Helsinki University Central Hospital; Institute of Biomedicine, Pharmacology, University of Helsinki.

RESULTS

At baseline, the rate of oxidation was higher in nonsmokers than in smokers. The lag phase increased significantly after the supplementation of vitamin E both in smokers and nonsmokers. Native LDL dose dependently tended to reduce the viability of endothelial cells in vitro more markedly when isolated from smokers than from nonsmokers. Vitamin E supplementation had no beneficial effect on the cytotoxicity of oxidized LDLs in endothelial cell culture. On the other hand, simultaneous administration of Trolox, the water-soluble analogue of vitamin E, attenuated the LDL cytotoxicity on endothelial cells. The vitamin E supplementation to LDL donors attenuated the increase in prostacyclin production both in smokers and nonsmokers.

CONCLUSION

Supplementation of LDL donors (healthy male volunteers on habitual fish diet) with vitamin E increased the lag phase of LDL oxidation, but, on the other hand, did not influence in vitro cytotoxicity of LDL, or prostacyclin production.

Serum selenium concentrations in chronic pancreatitis and controls

BACKGROUND

In the light of the recent hypothesis that one cause of pancreatic damage may be related to the toxic action of oxygen free radicals [Braganza JM. The pathogenesis of pancreatitis. Manchester: Manchester University Press; 1991; Braganza JM. A framework for the aetiogenesis of chronic pancreatitis. Digestion 1998;59(Suppl. 4):1-12], we were prompted to assess the role of selenium in pancreatic disease.

OBJECTIVE

The objective of the study was to establish whether or not there is any correlation between selenium levels and the degree of impairment of exocrine pancreatic function in patients suffering from chronic pancreatitis.

PATIENTS

Two groups of subjects were recruited, the first consisting of 38 patients with clinically quiescent chronic pancreatitis of alcoholic origin and the second of 48 control subjects selected from among healthy volunteers attending our Transfusion Centre.

METHODS

Body mass index, smoking and drinking habits were evaluated and selenium serum levels were assayed in all subjects. The patients with pancreatic disease were subdivided into three groups on the basis of lipase output assayed with a duodenal probe. RESULTS.: Selenium serum levels in the chronic pancreatitis group as a whole were found to be significantly lower than in the control group, but when they were analysed in the three distinct subgroups, a significant difference was found against control group only in the groups with severe and moderate exocrine pancreatic insufficiency.

CONCLUSIONS

The mean serum selenium levels were lower in chronic pancreatitis patients than control.

Mitochondrial dysfunction in cardiovascular disease

Whereas the pathogenesis of atherosclerosis has been intensively studied and described, the underlying events that initiate cardiovascular disease are not yet fully understood. A substantial number of studies suggest that altered levels of oxidative and nitrosoxidative stress within the cardiovascular environment are essential in the development of cardiovascular disease; however, the impact of such changes on the subcellular or organellar components and their functions that are relevant to cardiovascular disease inception are less understood. In this regard, studies are beginning to show that mitochondria not only appear susceptible to damage mediated by increased oxidative and nitrosoxidative stress, but also play significant roles in the regulation of cardiovascular cell function. In addition, accumulating evidence suggests that a common theme among cardiovascular disease development and cardiovascular disease risk factors is increased mitochondrial damage and dysfunction. This review discusses aspects relating mitochondrial damage and function to cardiovascular disease risk factors and disease development.

Oral vitamin C ameliorates smoking-induced arterial wall stiffness in healthy volunteers

We have investigated whether the oral administration of vitamin C could prevent smoking-induced acceleration of arterial stiffness in healthy volunteers. Subjects were pretreated with 2 g vitamin C and their heart rate (HR), mean blood pressure (MBP), and brachial-ankle pulse wave velocity (baPWV) were measured before and after smoking. Smoking significantly increased the HR, MBP, baPWV (13, 6.4, 7.0%). Vitamin C treatment significantly reduced the smoking-induced elevation in baPWV at 0 min (- 58.5%, p = 0.0002) without affecting HR or MBP. These findings suggest that oral vitamin C treatment prevents smoking-induced acceleration in arterial stiffness through reducing endothelial dysfunction.

Formation of 8-isoprostaglandin F2alpha and prostaglandin E2 in carrageenan-induced air pouch model in rats

To investigate a possible role of 8-isoprostaglandin F2alpha in inflammation, 8-isoprostaglandin F2alpha and prostaglandin E2 levels were determined by enzyme immunoassay (EIA) in carrageenan-induced air pouch model in rats. In this model, 8-isoprostaglandin F2alpha and prostaglandin E2 levels were found to be increased significantly. To evaluate whether this increase was due to the development of inflammation or solely to cyclooxygenase-2 induction, a lipopolysaccharide-induced air pouch model, in which only cyclooxygenase-2 induction occurs without inflammation, was used. In this model, 8-isoprostaglandin F2alpha was also found to be increased parallel to the increase in prostaglandin E2 level. Cyclooxygenase-dependent formation of 8-isoprostaglandin F2alpha was investigated in carrageenan-induced air pouch model by administrating nonselective cyclooxygenase inhibitor indomethacin, selective cyclooxygenase-1 inhibitor valeryl salicylate or selective cyclooxygenase-2 inhibitor SC-582368 (4-(5-(4-chlorophenyl)-3-3-trifluoromethyl)-1H-pyrazol-1-yl)benzenesulfonanmide) 1 h before carrageenan injection. All these inhibitors significantly inhibited the production of 8-isoprostaglandin F2alpha and prostaglandin E2. These findings show that 8-isoprostaglandin F2alpha can be formed in carrageenan-induced air pouch model in rats. The formation of 8-isoprostaglandin F2alpha in lipopolysaccharide-induced air pouch model and the inhibition of its production by various cyclooxygenase inhibitors provide evidence for cyclooxygenase-dependent formation of isoprostanes in this model.

Isoprostanes: markers and mediators of oxidative stress

Some years ago it was discovered that prostaglandin F2-like compounds are formed in vivo by nonenzymatic free radical-catalyzed peroxidation of arachidonic acid. Because these compounds are a series of isomers that contain the prostane ring of prostaglandins, they were termed F2-isoprostanes. Intermediates in the isoprostane pathway are prostaglandin H2-like compounds that become reduced to form F2-isoprostanes but also undergo rearrangement in vivo to form E2-, D2-, A2-, J2-isoprostanes, isothromboxanes, and highly reactive gamma-ketoaldehydes, termed isoketals. Analogous compounds have also been shown to be formed from free radical mediated oxidation of docosoahexaenoic acid. Because docosahexaenoic acid is highly enriched in neurons, these compounds have been termed neuroprostanes and neuroketals. An important aspect of the discovery of isoprostanes is that measurement of F2-isoprostanes has emerged as one of the most reliable approaches to assess oxidative stress status in vivo, providing an important tool to explore the role of oxidative stress in the pathogenesis of human disease. Measurement of F4-neuroprostanes has also proved of value in exploring the role of oxidative stress in neurodegenerative diseases. Products of the isoprostane pathway have been found to exert potent biological actions and therefore may participate as physiological mediators of disease.

Active smoking and a history of smoking are associated with enhanced prostaglandin F(2alpha), interleukin-6 and F2-isoprostane formation in elderly men

The underlying mechanisms by which smoking induces cardiovascular diseases are largely unknown. The effect of smoking status on the cyclooxygenase (COX)-mediated inflammatory indicator prostaglandin F(2alpha) (PGF(2alpha)) has never been studied. Associations of cytokines and antioxidants and smoking status, have shown conflicting results. Urinary 15-keto-dihydro-PGF(2alpha) (a major metabolite of PGF(2alpha)), serum interleukin-6 (IL-6) and high sensitivity C-reactive protein (hsCRP), serum amyloid protein A (SAA), urinary 8-iso-PGF(2alpha) (an F(2)-isoprostane, indicator of oxidative stress), and serum alpha-tocopherol were quantified in a population-based sample (n = 642) of 77-year old men without diabetes. Fifty-five men were current smokers and 391 former smokers. Inflammatory indicators were increased in current smokers (15-keto-dihydro-PGF(2alpha), P < 0.001; IL-6, P = 0.01) than non-smokers. 8-iso-PGF(2alpha) was increased (P < 0.01) and alpha-tocopherol reduced (P < 0.001) in current smokers. Further, former smokers had increased formation of 15-keto-dihydro-PGF(2alpha), IL-6 and 8-iso-PGF(2alpha) compared non-smokers. This is the first study to show that smokers have increased PGF(2alpha) formation, thus enhanced COX-mediated inflammation, in addition to elevated levels of cytokines and isoprostanes. Subclinical COX- and cytokine-mediated inflammation and oxidative stress are ongoing processes not only in active smokers but also in former smokers which may contribute to the accelerated atherosclerosis associated with smoking.

Non-invasive biomarkers of oxidative stress: reproducibility and methodological issues

Oxidative stress is the hallmark of various chronic inflammatory lung diseases. Increased concentrations of reactive oxygen species (ROS) in the lungs of such patients are reflected by elevated concentrations of oxidative stress markers in the breath, airways, lung tissue and blood. Traditionally, the measurement of these biomarkers has involved invasive procedures to procure the samples or to examine the affected compartments, to the patient's discomfort. As a consequence, there is a need for less or non-invasive approaches to measure oxidative stress. The collection of exhaled breath condensate (EBC) has recently emerged as a non-invasive sampling method for real-time analysis and evaluation of oxidative stress biomarkers in the lower respiratory tract airways. The biomarkers of oxidative stress such as H2O2, F2-isoprostanes, malondialdehyde, 4-hydroxy-2-nonenal, antioxidants, glutathione and nitrosative stress such as nitrate/nitrite and nitrosated species have been successfully measured in EBC. The reproducibility, sensitivity and specificity of the methodologies used in the measurements of EBC oxidative stress biomarkers are discussed. Oxidative stress biomarkers also have been measured for various antioxidants in disease prognosis. EBC is currently used as a research and diagnostic tool in free radical research, yielding information on redox disturbance and the degree and type of inflammation in the lung. It is expected that EBC can be exploited to detect specific levels of biomarkers and monitor disease severity in response to appropriate prescribed therapy/treatment.

Ascorbic acid improves impaired venous and arterial endothelium-dependent dilation in smokers

AIM

To compare the acute effects of ascorbic acid on vasodilation of veins and arteries in vivo.

METHODS

Twenty-six healthy non-smokers and 23 healthy moderate smokers were recruited in this study. The dorsal hand vein compliance technique and flow-mediated dilation were used. Dose-response curves to bradykinin and sodium nitroprusside were constructed to test the endothelium-dependent and -independent relaxation before and after acute infusion of ascorbic acid.

RESULTS

Smokers had an impaired venodilation with bradykinin compared with non-smokers (68.3%+/-13.2% vs 93.7%+/-20.1%, respectively; P<0.05). Ascorbic acid administration in the dorsal hand vein significantly increased the venodilation with bradykinin in smokers (68.3%+/-13.2% vs 89.5%+/-6.3% before and after infusion, respectively; P<0.05) but not in non-smokers (93.7%+/-20.1% vs 86.4%+/-12.4% before and after infusion, respectively). Similarly, the arterial response in smokers had an impaired endothelium-dependent dilation compared with that in non-smokers (8.8%+/-2.7% vs 15.2%+/-2.3%, respectively; P<0.05) and ascorbic acid restored this response in smokers (8.8%+/-2.7% vs 18.7%+/-6.5% before and after infusion, respectively; P<0.05), but no difference was seen in non-smokers (15.2%+/-2.3% vs 14.0%+/-4.4% before and after infusion, respectively). The endothelium-independent dilation did not differ in both the groups studied. No important hemodynamic change was detected using the Portapress device.

CONCLUSION

Smokers had impaired endothelium-dependent vasodilation responsiveness in both arterial and venous systems. Ascorbic acid restores this responsiveness in smokers.

Cyclooxygenase-mediated prostaglandin F2alpha is decreased in an elderly population treated with low-dose aspirin

Low-dose aspirin (acetylsalicylic acid) is used as prophylaxis against cardiovascular diseases. The effect of aspirin on inflammation and oxidative stress, processes known to be involved in cardiovascular diseases, are not fully known. The cyclooxygenase(COX)-mediated inflammatory indicator prostaglandin F2alpha (PGF2alpha) (15-keto-dihydro-PGF2alpha), cytokine-mediated inflammatory indicators (interleukin-6, high-sensitivity C-reactive protein, serum amyloid A protein), and oxidative stress indicators (8-iso-PGF2alpha, tocopherols) were quantified in men with daily 75 mg of aspirin (n=175) and control men (n=464), all of age 77, in a cross-sectional study. Men treated with aspirin had decreased levels of urinary 15-keto-dihydro-PGF2alpha than controls (P<0.01), independent of possible cardiovascular risk factors. Aspirin-treated men had increased levels of alpha-tocopherol than controls (P<0.05). This is the first study to indicate that low-dose aspirin treatment is associated with decreased levels of PGF2alpha. This observation suggests a possible COX-mediated anti-inflammatory effect of low-dose aspirin, which should be further confirmed by intervention studies.

Only two-week smoking cessation improves platelet aggregability and intraplatelet redox imbalance of long-term smokers

OBJECTIVES

We investigated whether and how soon smoking cessation ameliorates the smoking-induced intracellular oxidative stress and platelet aggregability in long-term smokers.

BACKGROUND

Smoking is a major risk factor of atherothrombosis. Smoking cessation reduces cardiac events. However, the underlying mechanisms of the beneficial effects remain to be elucidated.

METHODS

Twenty-seven male long-term smokers were divided into two groups. Group A (n = 14) quit smoking for four weeks whereas group B (n = 13) resumed smoking two weeks after quitting. Smoking status was monitored by measurement of urinary cotinine. Using gel-filtered platelets, agonist (adenosine diphosphate and collagen)-induced platelet aggregation, platelet-derived nitric oxide (PDNO), intraplatelet nitrotyrosine production, intraplatelet levels of the reduced form of glutathione (GSH) and its oxidized form (GSSG), and urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and urinary 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)), as markers of systemic oxidative stress, were measured. The baseline measurements were similar between the two groups.

RESULTS

Smoking cessation quickly reduced agonist-induced platelet aggregations, intraplatelet nitrotyrosine level, and urinary productions of 8-OHdG and 8-iso-PGF(2alpha) by two weeks in both groups. In group A, they were maintained at the low levels until four weeks, whereas they were reversed by resmoking in group B; PDNO release and intraplatelet GSH/GSSG ratio were time-dependently increased by smoking cessation but reversed by resmoking.

CONCLUSIONS

The present findings are the first demonstration that only two weeks of smoking cessation can ameliorate the enhanced platelet aggregability and intraplatelet redox imbalance in long-term smokers, possibly by decreasing oxidative stress. Our findings may strengthen the motivation for smokers to quit smoking.

Biomarkers of oxidative stress study III. Effects of the nonsteroidal anti-inflammatory agents indomethacin and meclofenamic acid on measurements of oxidative products of lipids in CCl4 poisoning

Plasma and urinary levels of malondialdehyde-like products (MDA) and isoprostanes were identified as markers of in vivo lipid peroxidation in an animal model of CCl4 poisoning. We sought to determine the extent to which the formation of these oxidation products is influenced by inhibition of the cyclooxygenase enzymes which catalytically generate proinflammatory lipid peroxidation products known as prostaglandins and thromboxane. In the present studies, after induction of oxidant stress in rats with CCl4, lipid peroxidation products measured in plasma and urine demonstrate that isoprostanes and MDA can be partially inhibited by cyclooxygenase inhibitors, albeit to different extents. The lowering of isoprostane and MDA formation, however, may not to due primarily to the diminution of catalytic generation of isoprostanes or MDA by the cyclooxygenases but, rather, may be the result of the suppression of nonenzymatic lipid peroxidation. This is suggested since 8,12-iso-iPF2alpha-VI is also reduced by indomethacin, yet, unlike other isoprostanes and MDA, it is not generated catalytically by the cyclooxygenase. Thus, although the two cyclooxygenase inhibitors we tested have statistically significant effects on the measurements of both isoprostanes and MDA in this study, the results provide evidence that these lipid-degradation products primarily constitute markers of oxidative stress.

Facilitated nitration and oxidation of LDL in cigarette smokers

BACKGROUND

Cigarette smoking increases the risk of developing atherosclerosis and ischaemic heart disease. Smoking-induced oxidative stress is considered to favour oxidation of low-density lipoprotein (LDL) and subsequently promotes the atherogenic process. We investigated whether peroxynitrite, a reaction product of cigarette smoke, is involved in facilitated oxidation of LDL in smokers.

MATERIALS AND METHODS

Plasma LDL was obtained from 10 healthy asymptomatic cigarette smokers and 10 healthy nonsmokers. The state of enhanced oxidative stress in the plasma was assessed by LDL subfraction assay using anion-exchange high-performance liquid chromatography (AE-HPLC) and measurements of thiobarbituric acid-reactive substances (TBARS), 8-hydroxydeoxyguanosine (8-OHdG), vitamin E, 3-nitrotyrosine and 3-chlorotyrosine.

RESULTS

Smokers showed a significantly higher level of TBARS and 8-OHdG as well as a significantly lower level of vitamin E than nonsmokers, even after stopping smoking for 10 h or more. The LDL subfraction assay demonstrated an increase in oxidatively modified LDL, as expressed by lower levels of LDL1 and higher levels of LDL2. The 3-nitrotyrosine levels in apolipoprotein B in LDL were significantly higher in smokers than nonsmokers, while the 3-chlorotyrosine levels remained unchanged. In addition, these changes observed in the smokers were further accelerated within 30 min after resumption of cigarette smoking when compared with the levels before smoking resumption.

CONCLUSION

The present study suggests that peroxynitrite plays a significant role in oxidative modification of plasma LDL induced by cigarette smoking.

Cigarette smokers have decreased lymphocyte and platelet alpha-tocopherol levels and increased excretion of the gamma-tocopherol metabolite gamma-carboxyethyl-hydroxychroman (gamma-CEHC)

Cigarette smoking is associated with increased oxidative stress and increased risk of degenerative disease. As the major lipophilic antioxidant, requirements for vitamin E may be higher in smokers due to increased utilisation. In this observational study we have compared vitamin E status in smokers and non-smokers using a holistic approach by measuring plasma, erythrocyte, lymphocyte and platelet alpha- and gamma-tocopherol, as well as the specific urinary vitamin E metabolites alpha- and gamma-carboxyethyl-hydroxychroman (CEHC). Fifteen smokers (average age 27 years, smoking time 7.5 years) and non-smokers of comparable age, gender and body mass index (BMI) were recruited. Subjects completed a 7-day food diary and on the final day they provided a 24 h urine collection and a 20 ml blood sample for measurement of urinary vitamin E metabolites and total vitamin E in blood components, respectively. No significant differences were found between plasma and erythrocyte alpha- and gamma-tocopherol in smokers and non-smokers. However, smokers had significantly lower alpha-tocopherol (mean+/-SD, 1.34+/-0.31 micromol/g protein compared with 1.94+/-0.54, P = 0.001) and gamma-tocopherol (0.19+/-0.04 micromol/g protein compared with 0.26+/-0.08, P = 0.026) levels in their lymphocytes, as well as significantly lower alpha-tocopherol levels in platelets (1.09+/-0.49 micromol/g protein compared with 1.60+/-0.55, P = 0.014; gamma-tocopherol levels were similar). Interestingly smokers also had significantly higher excretion of the urinary gamma-tocopherol metabolite, gamma-CEHC (0.49+/-0.25mg/g creatinine compared with 0.32+/-0.16, P = 0.036) compared to non-smokers, while their alpha-CEHC (metabolite of alpha-tocopherol) levels were similar. There was no significant difference between plasma ascorbate, urate and F2-isoprostane levels. Therefore in this population of cigarette smokers (mean age 27 years, mean smoking duration 7.5 years), alterations to vitamin E status can be observed even without the more characteristic changes to ascorbate and F2-isoprostanes. We suggest that the measurement of lymphocyte and platelet vitamin E may represent a valuable biomarker of vitamin E status in relation to oxidative stress conditions.

Increased serum iron may contribute to enhanced oxidation of low-density lipoprotein in smokers in part through changes in lipoxygenase and catalase

BACKGROUND

Increased oxidative stress is considered to be causative for cardiovascular disease (CVD) in smokers, but its mechanisms are still unclear. We compared oxidative stress markers between male smokers and male nonsmokers.

METHODS

Twenty-three healthy men (11 nonsmokers and 12 smokers) were enrolled, and blood samples after 12 h of fasting were collected to assess plasma lipids and oxidative stress markers. The effects of iron loading on 12-lipoxygenase (12-LO) expression and activity in human umbilical vein endothelial cells (HUVECs) were tested in vitro to investigate the relevance of iron to oxidation potential in vivo.

RESULTS

Higher levels of plasma-oxidized low-density lipoprotein (LDL) and lipid peroxide (LPO), and higher oxidizability of LDL were observed in smokers than in nonsmokers. Higher levels of serum iron and lower levels of plasma vitamin E were observed in smokers than in nonsmokers. Stepwise multiple regression analysis showed that serum iron was an independent determinant for both plasma-oxidized LDL and lag time of LDL oxidation. Iron loading enhanced 12-LO expression threefold and its activity 1.5-fold. Moreover, iron loading decreased catalase expression by 50% and significantly reduced its activity by 75%.

CONCLUSIONS

Enhanced oxidative stress in smokers may be due to increased iron levels. Iron-induced modulation of expression and activity of 12-LO and catalase may be relevant to increased iron-related oxidative stress as observed in smokers.

Inhibition of lipoprotein lipid oxidation

According to the oxidative modification hypothesis, antioxidants that inhibit the oxidation of low-density lipoprotein (LDL) are expected to attenuate atherosclerosis, yet not all antioxidants that inhibit LDL oxidation in vitro inhibit disease in animal models of atherosclerosis. As with animal studies, a benefit with dietary supplements of antioxidants in general and vitamin E in particular was anticipated in humans, yet the overall outcome of large, randomized controlled studies has been disappointing. However, in recent years it has become clear that the role of vitamin E in LDL oxidation and the relationship between in vitro and in vivo inhibition of LDL oxidation are more complex than previously appreciated, and that oxidative events in addition to LDL oxidation in the extracellular space need to be considered in the context of an antioxidant as a therapeutic drug against atherosclerosis. This review focuses on some of these complexities, proposes a novel method to assess in vitro 'oxidizability' of lipoprotein lipids, and summarizes the present situation of development of antioxidant compounds as drugs against atherosclerosis and related cardiovascular disorders.

Fluvastatin Ameliorates the Hyperhomocysteinemia-Induced Endothelial Dysfunction-The Antioxidative Properties of Fluvastatin-

BACKGROUND

Hyperhomocysteinemia induces vascular endothelial dysfunction, contributing to a predisposition to the onset and/or progression of atherosclerosis. The major mechanism suggested for the adverse effect of homocysteine on vascular function seems to involve oxidative stress. Thus, we hypothesized that the administration of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor fluvastatin, which is experimentally demonstrated to have antioxidative properties as one of its pleiotropic effects, is a useful strategy for eliminating the detrimental events induced by hyperhomocysteinemia.

METHODS AND RESULTS

In diet-induced hyperhomocysteinemic rats, we estimated oxidative stress and assessed endothelium-dependent vasodilatation. Hyperhomocysteinemia induced significant increases in urinary 8-isoprostaglandin F2alpha-III excretion and vascular superoxide generation, and impaired endothelium-dependent vasodilatation. Additional oral administration of the antioxidant fluvastatin or vitamin E, which normalized increased oxidative stress induced by hyperhomocysteinemia, ameliorated endothelial dysfunction.

CONCLUSIONS

Hyperhomocysteinemia, even mild to moderate, induces endothelial dysfunction through its oxidative effect. The antioxidant fluvastatin was able to cancel out the oxidative stress induced by hyperhomocysteinemia and ameliorate endothelial dysfunction. Clinical use of fluvastatin might be a potent strategy for eliminating the detrimental events induced by hyperhomocysteinemia as well as hyperlipidemia. In addition to lowering homocysteine by means of folate supplementation, administration of the antioxidants is expected to be a potentially effective anti-homocysteine therapy.

Factors regulating isoprostane formation in vivo

Discovery of the F2-isoprostanes, a group of prostaglandin F2-like compounds biosynthesized from arachidonic acid nonenzymatically, has uncovered a new and novel facet of free radical biology. Some of these compounds are bioactive and thus may mediate adverse effects associated with oxidant stress. F2-Isoprostanes have also been shown to be reliable biomarkers of lipid peroxidation. Factors influencing their formation and metabolism have been studied to some extent, although much remains to be determined. The purpose of this review is to summarize our current knowledge of conditions that modulate endogenous generation of these compounds. Isoprostanes have a wide daily variation in secretion in humans. Although normal levels can be defined, these compounds are found in increased concentrations in various pathophysiological states, including ischemia-reperfusion injury, atherosclerosis, and diabetes, and in experimental conditions of oxidative stress and inflammation. Alterations in isoprostane biosynthesis, secretion, and excretion in normal physiology and in pathophysiological states are due to the various types of endogenous and exogenous regulatory mechanisms that control the availability of precursors required for isoprostane synthesis, such as dietary and tissue arachidonic acid content, oxygen concentration, and the generation of various free radical species. Selected aspects of issues related to isoprostane formation and metabolism in vivo will be examined herein.