Women and smokers have elevated urinary F(2)-isoprostane metabolites: a novel extraction and LC-MS methodology

Oxidative Stress and Cardiovascular Risk Factors: The Coronary Artery Risk Development in Young Adults (CARDIA) Study

Introduction—Oxidative stress is linked to cardiovascular diseases (CVD) and is suggested to vary by sex. However, few population-level studies have explored these associations and the majority comprise populations with advanced CVD. We assessed urinary isoprostane concentrations, a standard measure of oxidative stress, in a relatively young and healthy cohort, hypothesizing that higher oxidative stress is associated with an adverse cardiometabolic profile and female sex. Methods—Oxidative stress was measured in 475 women and 266 men, aged 48–55 years, from the Coronary Artery Risk Development in Young Adults (CARDIA) study using urinary 8-isoprostane (IsoP) and 2,3-dinor-8-isoprostane (IsoP-M). Multivariable-adjusted regression was used to evaluate cross-sectional associations. As secondary analysis, previously measured plasma F2-isoprostanes (plasma IsoP) from another CARDIA subset was similarly analyzed. Results—Mean (SD) ages for men and women were 52.1(2.3) and 52.2(2.2) years, respectively (p = 0.46), and 39% of the participants self-identified as Black (vs. White). Before adjustments, female sex was associated with higher median urinary IsoP (880 vs. 704 ng/g creatinine in men; p < 0.01) and IsoP m (1675 vs. 1284 ng/g creatinine in men; p < 0.01). Higher body mass index (BMI), high-density cholesterol (HDL-C), and triglycerides, current smoking, and less physical activity were associated with higher oxidative stress. Diabetes was not associated with urinary IsoP but was associated with lower IsoP m and plasma IsoP. Higher serum creatinine showed diverging associations with higher plasma and lower urinary isoprostane concentrations. Conclusions—Different isoprostane entities exhibit varying association patterns with CVD risk factors, and therefore are complementary, rather than interchangeable, in assessment of oxidative stress. Still, consistently higher isoprostanes among women, smokers, less active persons, and those with higher BMI and plasma triglycerides could reflect higher oxidative stress among these groups. While urinary isoprostanes are indexed to urinary creatinine due to variations in concentration, caution should be exercised when comparing groups with differing serum creatinine.

A Novel UHPLC-MS/MS Method for Measuring 8-iso-Prostaglandin F2α in Bronchoalveolar Lavage Fluid

In August 2019, the Centers for Disease Control and Prevention (CDC) received the first reports of lung injuries that were eventually termed e-cigarette, or vaping, product use–associated lung injury (EVALI). As part of the investigation, CDC laboratories rapidly developed assays for analyzing substances in bronchoalveolar lavage (BAL) fluid collected from EVALI case patients. This report describes the development and validation of a high-throughput isotope dilution UHPLC-MS/MS method for measuring a major oxidative stress biomarker, 8-iso-prostaglandin F_2α (8-isoprostane), in BAL fluid samples. The method showed good sensitivity, 17.6 pg/ml LOD, and requires only 50 μl of sample volume. The method had high throughput with an analytical run time of 11 min. The within-day and between-day coefficient of variation (CV) were below 2%. Accuracy, calculated from spiked recovery, at three spiking levels, ranged from 95.5–101.8%. This novel UHPLC-MS/MS method characterizes oxidative stress in lung epithelial tissue and thus helps to elucidate potential pathologic processes.

Adiponectin agonist treatment in diabetic pregnant rats

Gestational diabetes mellitus (GDM) reduces maternal adiponectin and docosahexaenoic acid (DHA) materno-fetal transfer, which may have negative consequences for the offspring. Our aim was to evaluate the effects of the administration of a novel adiponectin agonist (AdipoRon) to GDM rats on the long-term consequences in glycaemia and fatty acids (FA) profile in the offspring. Pregnant rats were randomized to three groups: GDM rats (GDM, n = 8), GDM rats treated with AdipoRon (GDM + ADI, n = 9), and control rats (n = 10). Diabetes was induced with streptozotocin (50 mg/kg) on day 12 of gestation. GDM+ADI received 50 mg/kg/day AdipoRon from day 14 until delivery. Glycaemia and FA profile were determined in mothers and adult offspring (12 weeks old). AdipoRon tended to reduce fasting glucose in diabetic mothers. Diabetic rats presented the foetus with intrauterine growth restriction and higher adiposity, which tried to be counteracted by AdipoRon. In the adult offspring, both GDM + ADI and control animals showed better glucose recovery after oral glucose overload with respect to GDM. DHA in offspring plasma was significantly reduced in both GDM and GDM + ADI compared to controls (P = 0.043). Nevertheless, n-6/n-3 polyunsaturated FA (PUFA) ratio improved in plasma of GDM + ADI adult offspring (GDM: 14.83 ± 0.85a%; GDM + ADI: 11.49 ± 0.58b%; control: 10.03 ± 1.22b%, P = 0.034). Inflammatory markers and oxidative stress were reduced in the adult offspring of AdipoRon-treated mothers. In conclusion, AdipoRon administration to pregnant diabetic rats improved glycaemia in the mothers and long-term glucose tolerance in the offspring. In addition, it tended to reduce excessive foetal fat accumulation and improved n-6/n-3 PUFA ratio significantly in offspring at the adult state.

Moderate Red Wine Consumption Increases the Expression of Longevity-Associated Genes in Controlled Human Populations and Extends Lifespan in Drosophila melanogaster

The beneficial effects of moderate red wine consumption on cardiovascular health are well known. The composition of red wine includes several compounds, such as the phytoestrogen resveratrol, that exert these beneficial effects, although not all the mechanisms by which they act are known. Our aim was to study the effect of red wine consumption on longevity-related genes in controlled human populations, such as cloistered nuns. We found that the expression of catalase, manganese-superoxide dismutase, Sirt1, and p53 was increased in peripheral blood mononuclear cells after 14 days of moderate red wine consumption. This increase was accompanied by an enhanced metabolic wellness: fatty acids, cholesterol, branched chain amino acids (isoleucine and leucine), ketone bodies (acetoacetate), bacterial co-metabolites (trimethylamine), and cellular antioxidants (taurine) contributed to a change in metabolic profile after moderate red wine consumption by the nuns. No serious unwanted side effects were observed. Finally, we tested the effect of moderate red wine consumption on longevity in a controlled animal population, such as D. melanogaster, and found that it increased average life span by 7%. In conclusion, moderate red wine consumption increases the expression of key longevity-related genes and improves metabolic health in humans and increases longevity in flies.

Biomarkers of Toxicant Exposure and Inflammation Among Women of Reproductive Age Who Use Electronic or Conventional Cigarettes

Background: Electronic cigarettes (e-cigarettes) generally have a more favorable toxicant profile than conventional cigarettes; however, limited information exists for women of reproductive age (WRA). Our aim was to compare biomarkers of toxicant exposure, inflammation, and oxidative stress among WRA who self-report exclusive e-cigarette use, exclusive cigarette smoking, or never tobacco use (controls). Methods: Multivariable linear regression models were used to compare the geometric means of urinary biomarkers of toxicant exposure and their metabolites, serum markers of inflammation [highly sensitive C-reactive protein, soluble intercellular adhesion molecule (sICAM), interleukin 6, fibrinogen], and a measurement of oxidative stress [prostaglandin F2a-8-isoprostane (F2PG2a)] among WRA from the Population Assessment of Tobacco and Health survey. Results: E-cigarette users had higher levels of lead, tobacco-specific nitrosamines, nicotine metabolites, and some volatile organic compounds (VOCs) than controls. Except for cadmium and lead, e-cigarette users had lower levels of the analyzed urinary toxicant biomarkers compared with cigarette smokers. Cigarette smokers had higher levels of all the biomarkers of toxicant exposure than controls. There were no significant differences in the levels of markers of inflammation and oxidative stress between e-cigarette users and controls. E-cigarette users and controls had lower levels of sICAM and F2PG2a than cigarette smokers. Conclusion: WRA who use e-cigarettes had lower levels of some of the evaluated urinary biomarkers of toxicant exposure and serum biomarkers of inflammation and oxidative stress than those who smoke cigarettes, but higher lead, nicotine metabolites, and some VOCs than controls, which can increase health risks.

The Role of Urine F2-ISOPROSTANE CONcentration in Delayed Cerebral Ischemia after Aneurysmal Subarachnoid Haemorrhage-A Poor Prognostic Factor

Background: The pathophysiology of delayed cerebral ischemia (DCI) remains unclear. One of the hypotheses suggests that reactive oxygen species play a role in its onset. Thus, we studied F2-isoprostanes (F2-IsoPs)—oxidative stress biomarkers. Our goal was to improve the early diagnosis of DCI in a non-invasive way. Methods: We conducted a prospective single center analysis of 38 aneurysmal subarachnoid hemorrhage patients. We assessed urine F2-IsoP concentration using immunoenzymatic arrays between the first and fifth day after bleeding. A correlation between urine F2-IsoP concentration and DCI occurrence was examined regarding clinical conditions and outcomes. Results: The urine F2-IsoP concentrations were greater than those in the control groups (p < 0.001). The 3rd day urine F2-IsoPs concentrations were correlated with DCI occurrence (p < 0.001) and long term outcomes after 12 months (p < 0.001). Conclusions: High levels of urine F2-IsoPs on day 3 can herald DCI.

Urinary mutagenicity and oxidative status of wildland firefighters working at prescribed burns in a Midwestern US forest

OBJECTIVE

Wildland firefighters (WLFFs) experience repeated exposures to wildland fire smoke (WFS). However, studies about WLFFs remain regionally limited. The objective of this study was to assess the effect of WFS exposure on urinary mutagenicity and cell oxidation among WLFFs who work at prescribed burns in the Midwestern USA.

METHODS

A total of 120 spot urine samples was collected from 19 firefighters right before (pre-shift), immediately after (post-shift), and the morning (next-morning) following work shifts on prescribed burn days (burn days) and regular workdays (non-burn days). The levels of urinary mutagenicity, 8-isoprostane, malondialdehyde and oxidised guanine species (Ox-GS) were measured. Linear mixed-effect models were used to determine the difference of cross-shift changes in the concentrations of urinary biomarkers.

RESULTS

Post-shift levels of creatinine-corrected urinary mutagenicity and 8-isoprostane were non-significantly higher than pre-shift levels (1.16× and 1.64×; p=0.09 and 0.07) on burn days. Creatinine-corrected Ox-GS levels increased significantly in next-morning samples following WFS exposure (1.62×, p=0.03). A significant difference in cross-shift changes between burn and non-burn days was observed in 8-isoprostane (2.64×, p=0.03) and Ox-GS (3.00×, p=0.02). WLFFs who contained the fire (performed holding tasks) had a higher pre-morning to next-morning change in urinary mutagenicity compared with those who were lighting fires during the prescribed burns (1.56×, p=0.03).

CONCLUSIONS

Compared with the other regions, WLFFs who worked in Midwestern forests had an elevated urinary mutagenicity and systemic oxidative changes associated with WFS exposure at prescribed burns.

Identification and quantification of phenanthrene ortho-quinones in human urine and their association with lipid peroxidation

Although human exposure to polycyclic aromatic hydrocarbons (PAH) has been associated with in vivo oxidative damage, and hydroxyPAH metabolites have been used as biomarkers to assess PAH-induced oxidative stress, few studies have looked at the likely causative compounds for oxidative stress in humans - PAH quinones. We developed a method using pre-column derivatization - liquid chromatography-heated electrospray ionization-tandem mass spectrometry (LC-HESI-MS/MS) to analyze ortho-phenanthrene quinones (PheQs) in human urine. 1,2-PheQ and 3,4-PheQ were identified and quantified in 3 mL of human urine; their total concentrations were higher in cigarette smokers (0.79 ± 0.98 nmol/6h urine) than in nonsmokers (0.20 ± 0.98 nmol/6h urine) (p < 0.01). The total of 1,2-PheQ and 3,4-PheQ were more strongly correlated with urinary (Z)-7-[1R,2R,3R,5S)-3,5-dihydroxy-2-[(E,3S)-3-hydroxyoct-1-enyl]cyclopentyl]hept-5-enoic acid (8-iso-PGF_2α), a biomarker of lipid peroxidation (R² = 0.53, p < 0.001), than the other phenanthrene metabolites including phenanthrene tetraol (PheT), phenanthrene-1,2-dihydrodiol (1,2-PheD), and total phenanthrene phenols (OHPhe), consistent with the concept that PheQs and likely other PAH quinones play a causal role in the generation of reactive oxygen species (ROS) in humans. Thus, PheQs may be suitable as biomarkers to assess human exposure to oxygenated PAH and the subsequent oxidative damage. This study provides unique support, by analysis of human urinary metabolites, for the PAH quinone mediated oxidative damage hypothesis of PAH carcinogenesis.

A Randomized Controlled Trial of Long-Term (R)-α-Lipoic Acid Supplementation Promotes Weight Loss in Overweight or Obese Adults without Altering Baseline Elevated Plasma Triglyceride Concentrations

BACKGROUND

α-Lipoic acid (LA) is a dietary supplement for maintaining energy balance, but well-controlled clinical trials in otherwise healthy, overweight adults using LA supplementation are lacking.

OBJECTIVES

The primary objective was to evaluate whether LA supplementation decreases elevated plasma triglycerides in overweight or obese adults. Secondary aims examined if LA promotes weight loss and improves oxidative stress and inflammation.

METHODS

Overweight adults [n = 81; 57% women; 21-60 y old; BMI (in kg/m2) ≥ 25] with elevated plasma triglycerides ≥100 mg/dL were enrolled in a 24-wk, randomized, double-blind, controlled trial, assigned to either (R)-α-lipoic acid (R-LA; 600 mg/d) or matching placebo, and advised not to change their diet or physical activity. Linear models were used to evaluate treatment effects from baseline for primary and secondary endpoints.

RESULTS

R-LA did not decrease triglyceride concentrations, but individuals on R-LA had a greater reduction in BMI at 24 wk than the placebo group (-0.8; P = 0.04). The effect of R-LA on BMI was correlated to changes in plasma triglycerides (r = +0.50, P = 0.004). Improvement in body weight was greater at 24 wk in R-LA subgroups than in placebo subgroups. Women and obese participants (BMI ≥ 35) showed greater weight loss (-5.0% and -4.8%, respectively; both P < 0.001) and loss of body fat (-9.4% and -8.6%, respectively; both P < 0.005). Antioxidant gene expression in mononuclear cells at 24 wk was greater in the R-LA group (Heme oxygenase 1 [HMOX1] : +22%; P = 0.02) than in placebo. Less urinary F2-isoprostanes (-25%; P = 0.005), blood leukocytes (-10.1%; P = 0.01), blood thrombocytes (-5.1%; P = 0.03), and ICAM-1 (-7.4%; P = 0.04) at 24 wk were also observed in the R-LA group than in placebo.

CONCLUSIONS

Long-term LA supplementation results in BMI loss, greater antioxidant enzyme synthesis, and less potential for inflammation in overweight adults. Improved cellular bioenergetics is also evident in some individuals given R-LA.This trial was registered at clinicaltrials.gov as NCT00765310.

Determination of urinary prostaglandin E2 as a potential biomarker of ureteral stent associated inflammation

Ureteral stents are the most widely used surgical implant in urology. However, they may cause adverse effects to patients, including pain, discomfort, and inflammation. In this work, the inflammatory effect of stent placement and the associated elevation of cyclooxygenase-2 (COX-2) expression were observed. Furthermore, a capillary electrophoresis mass spectrometry (CE-MS) based approach was subsequently developed to quantify urinary prostaglandin E₂ (PGE₂), a COX-2 metabolite known to contribute to inflammatory renal diseases, to further interrogate the role of this pathway. Urine samples were cleaned and preconcentrated by solid-phase extraction (SPE), and an on-line sample stacking method was used for the enrichment of analytes. The accuracy, precision, and specificity of this method were validated. Standard addition methods were performed to assess the reliability of using deuterated internal standards (IS) in compensating the remaining matrix effect after SPE as well as the detector fluctuation. Through the analysis of 32 pig urine samples, a statistically significant increase of PGE₂ was observed in the stented group compared to the unstented (P = 0.01) and the recovered (P = 0.004) groups. This work determined that stent placement may contribute to COX-2-dependent inflammation and developed a reliable CE-MS based methodology to quantify PGE₂ in stented individuals that may further understand the biology of stent-associated inflammation and inform urologic patient management.

Lipidomic methodologies for biomarkers of chronic inflammation in nutritional research: ω-3 and ω-6 lipid mediators

The evolutionary history of hominins has been characterized by significant dietary changes, which include the introduction of meat eating, cooking, and the changes associated with plant and animal domestication. The Western pattern diet has been linked with the onset of chronic inflammation, and serious health problems including obesity, metabolic syndrome, and cardiovascular diseases. Diets enriched with ω-3 marine PUFAs have revealed additional improvements in health status associated to a reduction of proinflammatory ω-3 and ω-6 lipid mediators. Lipid mediators are produced from enzymatic and non-enzymatic oxidation of PUFAs. Interest in better understanding the occurrence of these metabolites has increased exponentially as a result of the growing evidence of their role on inflammatory processes, control of the immune system, cell signaling, onset of metabolic diseases, or even cancer. The scope of this review has been to highlight the recent findings on: a) the formation of lipid mediators and their role in different inflammatory and metabolic conditions, b) the direct use of lipid mediators as antiinflammatory drugs or the potential of new drugs as a new therapeutic option for the synthesis of antiinflammatory or resolving lipid mediators and c) the impact of nutritional interventions to modulate lipid mediators synthesis towards antiinflammatory conditions. In a second part, we have summarized methodological approaches (Lipidomics) for the accurate analysis of lipid mediators. Although several techniques have been used, most authors preferred the combination of SPE with LC-MS. Advantages and disadvantages of each method are herein addressed, as well as the main LC-MS difficulties and challenges for the establishment of new biomarkers and standardization of experimental designs, and finally to deepen the study of mechanisms involved on the inflammatory response.

Vitamin E absorption and kinetics in healthy women, as modulated by food and by fat, studied using 2 deuterium-labeled α-tocopherols in a 3-phase crossover design

BACKGROUND

Determining the human vitamin E [α-tocopherol (α-T)] requirement is difficult, and novel approaches to assess α-T absorption and trafficking are needed.

OBJECTIVE

We hypothesized that the dual-isotope technique, using 2 deuterium-labeled [intravenous (IV) d6- and oral d3-] α-T, would be effective in determining α-T fractional absorption. Further, defined liquid meal (DLM) fat or fasting would modulate α-T fractional absorption and lipoprotein transport.

METHODS

A 3-phase cr ossover design was used. At 0 h, participants received IV d6-α-T and consumed d3-α-T with a 600-kcal DLM (40% or 0% fat) followed by controlled meals or by the 0% fat DLM, a 12-h fast, and then controlled meals. Blood samples and fecal samples were collected at intervals and analyzed by LC-MS. Pharmacokinetic parameters were calculated from plasma tracer concentrations and enrichments. Fractional absorption was calculated from d3- to d6-α-T areas under the curve, from a novel mathematical model, and from the balance method (oral d3-α-T minus fecal d3-α-T excreted).

RESULTS

Estimated α-T fractional absorption during the 40% fat intervention was 55% ± 3% (mean ± SEM; n = 10), which was 9% less than during the 0% fat intervention (64% ± 3%, n = 10; P < 0.02). Fasting had no apparent effect (56% ± 3%, n = 7), except it slowed plasma oral d3-α-T appearance. Both balance data and model outcomes confirmed that the DLM fat did not potentiate d3-α-T absorption. During the IV emulsion clearance, HDL rapidly acquired d6-α-T (21 ± 2 nmol/L plasma per minute). During the first 8 h postdosing, triglyceride-rich lipoproteins (TRLs) were preferentially d3-α-T enriched relative to LDL or HDL, showing the TRL precursor role.

CONCLUSIONS

Quantitatively, α-T absorption is not limited by fat absence or by fasting. However, α-T leaves the intestine by a process that is prolonged during fasting and potentiated by eating, suggesting that α-T absorption is highly dependent on chylomicron assembly processes. This trial was registered at clinicaltrials.gov as NCT00862433.

Tobacco Smoke Exposure, Urban and Environmental Factors as Respiratory Disease Predictors in Italian Adolescents

Risk monitoring in childhood is useful to estimate harmful health effects at later stages of life. Thus, here we have assessed the effects of tobacco smoke exposure and environmental pollution on the respiratory health of Italian children and adolescents using spirometry and the forced oscillation technique (FOT). For this purpose, we recruited 188 students aged 6–19 years living in Chivasso, Italy, and collected from them the following data: (1) one filled out questionnaire; (2) two respiratory measurements (i.e., spirometry and FOT); and (3) two urine tests for Cotinine (Cot) and 15-F_2t-Isoprostane (15-F_2t-IsoP) levels. We found a V-shape distribution for both Cotinine and 15-F_2t-IsoP values, according to age groups, as well as a direct correlation (p = 0.000) between Cotinine and tobacco smoke exposure. These models demonstrate that tobacco smoke exposure, traffic, and the living environment play a fundamental role in the modulation of asthma-like symptoms (p = 0.020) and respiratory function (p = 0.007). Furthermore, the results from the 11–15-year group indicate that the growth process is a protective factor against the risk of respiratory disease later in life. Lastly, the FOT findings highlight the detrimental effects of tobacco smoke exposure and urbanization and traffic on respiratory health and asthma-like symptoms, respectively. Overall, monitoring environmental and behavioral factors in childhood can provide valuable information for preventing respiratory diseases in adulthood.

Longitudinal stability in cigarette smokers of urinary eicosanoid biomarkers of oxidative damage and inflammation

The urinary metabolites (Z)-7-[1R,2R,3R,5S)-3,5-dihydroxy-2-[(E,3S)-3-hydroxyoct-1-enyl]cyclopentyl]hept-5-enoic acid (8-iso-PGF2α), an F2-isoprostane and biomarker of oxidative damage, and "prostaglandin E2 metabolite" (PGE-M), a biomarker of inflammation, are elevated in cigarette smokers. However, there is little information in the literature on the longitudinal stability of these widely used biomarkers. In a large clinical trial involving 10 institutional sites, smokers were given, free of charge over a period of 20 weeks, Spectrum NRC600/601 research cigarettes containing 15.5 mg nicotine/g tobacco. All participants were instructed to smoke these cigarettes for the duration of the study. At weeks 4, 8, 12, 16, and 20, first morning urine voids were collected and analyzed for 8-iso-PGF2α and PGE-M using validated liquid chromatography-electrospray ionization-tandem mass spectrometry methods. The mean level of 8-iso-PGF2α at Week 4 was 1.34 ± 1.08 (S.D.) pmol/mg creatinine (N = 226) while that of PGE-M was 73.7 ± 113 (S.D.) pmol/mg creatinine (N = 232). The corresponding levels at Week 20 were 1.35 ± 0.93 (S.D.) pmol/mg creatinine (N = 209) for 8-iso-PGF2α and 74.2 ± 142 (S.D.) pmol/mg creatinine (N = 210) for PGE-M. There was variation in these values in the intervening weeks. The intra-class correlation coefficients (ICC) were 0.51 (95% CI, 0.45, 0.57) and 0.36 (0.30, 0.43), for 8-iso-PGF2α and PGE-M, respectively, indicating fair longitudinal stability for 8-iso-PGF2α and poorer longitudinal stability for PGE-M in cigarette smokers. Males had higher ICC values than females for both 8-iso-PGF2α and PGE-M. These results indicate that, in addition to cigarette smoking, endogenous processes of oxidative damage and inflammation influence the levels of these biomarkers over time among current smokers.

Lipoxidation in cardiovascular diseases

Lipids can go through lipid peroxidation, an endogenous chain reaction that consists in the oxidative degradation of lipids leading to the generation of a wide variety of highly reactive carbonyl species (RCS), such as short-chain carbonyl derivatives and oxidized truncated phospholipids. RCS exert a wide range of biological effects due to their ability to interact and covalently bind to nucleophilic groups on other macromolecules, such as nucleic acids, phospholipids, and proteins, forming reversible and/or irreversible modifications and generating the so-called advanced lipoxidation end-products (ALEs). Lipoxidation plays a relevant role in the onset of cardiovascular diseases (CVD), mainly in the atherosclerosis-based diseases in which oxidized lipids and their adducts have been extensively characterized and associated with several processes responsible for the onset and development of atherosclerosis, such as endothelial dysfunction and inflammation. Herein we will review the current knowledge on the sources of lipids that undergo oxidation in the context of cardiovascular diseases, both from the bloodstream and tissues, and the methods for detection, characterization, and quantitation of their oxidative products and protein adducts. Moreover, lipoxidation and ALEs have been associated with many oxidative-based diseases, including CVD, not only as potential biomarkers but also as therapeutic targets. Indeed, several therapeutic strategies, acting at different levels of the ALEs cascade, have been proposed, essentially blocking ALEs formation, but also their catabolism or the resulting biological responses they induce. However, a deeper understanding of the mechanisms of formation and targets of ALEs could expand the available therapeutic strategies.

An ultra-high-performance liquid chromatography tandem mass spectrometry method for oxidative stress biomarker analysis in wastewater

Reported herein is the development of an analytical method for the detection of four oxidative stress biomarkers in wastewater using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) and solid phase extraction (SPE). The following four biomarkers of oxidative stress and lipid peroxidation have been investigated: hydroxynonenal-mercapturic acid (HNE-MA), 8-iso-prostglandin F2beta (8-iso-PGF_2β), 8-nitroguanine (8-NO₂Gua) and 8-hydroxy-2-deoxyguanosine (8-OHdG). The method showed very good performance: accuracy (> 87%), precision (> 90%), method quantification limits (1.3-3.0 ng L^-1) and biomarker stability in wastewater in the case of HNE-MA, 8-OHdG and 8-iso-PGF_2β. In contrast, 8-NO₂Gua was found to be less stable in wastewater, which affected its method performance: accuracy (> 63%), precision (> 91%) and method quantification limits (85.3 ng L^-1). Application of the developed method resulted in, for the first time, HNE-MA being successfully observed and quantified within wastewater over a study period of a week (displayed average daily loads per capita of 48.9 ± 4.1 mg/1000/people/day). 8-iso-PGF_2β was detected with good intensity but could not be quantified due to co-elution with other isomers. 8-OHdG was detected, albeit at < MQL. This study demonstrates the potential for expanding on the possible endogenous biomarkers of health used in urban water fingerprinting to aid in measuring health in near-real time on a community-wide scale.

The relationship between vitamin C status, the gut-liver axis, and metabolic syndrome

Metabolic syndrome (MetS) is a constellation of cardiometabolic risk factors, which together predict increased risk of more serious chronic diseases. We propose that one consequence of dietary overnutrition is increased abundance of Gram-negative bacteria in the gut that cause increased inflammation, impaired gut function, and endotoxemia that further dysregulate the already compromised antioxidant vitamin status in MetS. This discussion is timely because "healthy" individuals are no longer the societal norm and specialized dietary requirements are needed for the growing prevalence of MetS. Further, these lines of evidence provide the foundational basis for investigation that poor vitamin C status promotes endotoxemia, leading to metabolic dysfunction that impairs vitamin E trafficking through a mechanism involving the gut-liver axis. This report will establish a critical need for translational research aimed at validating therapeutic approaches to manage endotoxemia-an early, but inflammation-inducing phenomenon, which not only occurs in MetS, but is also prognostic of more advanced metabolic disorders including type 2 diabetes mellitus, as well as the increasing severity of nonalcoholic fatty liver diseases.

Influence of smoking on levels of urinary 8-iso Prostaglandin F2α

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Cigarette smoking is an important modifiable risk factor for cardiovascular disease.

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Cigarette smoking affects oxidative stress markers such as 8-iso prostaglandin F2α.

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The effect of smoking on urinary 8-iso prostaglandin F2α levels was meta-analyzed.

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Urinary 8-iso prostaglandin F2α levels were increased in smokers.

Background

To evaluate the reduced-risk potential of alternative tobacco products, biomarkers that are involved in the biological pathways affected by cigarette smoking and smoking cessation are needed. Isoprostanes, a measure of oxidative stress, appear to be influenced by smoking and reversible upon smoking cessation and therefore could be a good biomarker. This review aims at quantifying the effect of smoking and smoking cessation on levels of urinary 8-iso prostaglandin F_2α (8-epi-PGF_2α), an isoprostane.

Methods

PubMed and Scopus databases were searched for publications that reported 8-epi-PGF_2α levels in smokers and nonsmokers as well as articles reporting the effect of smoking cessation on 8-epi-PGF_2α levels.

Results

Eighteen studies assessing 8-epi-PGF_2α levels by smoking status were identified. Five of the papers reported the results as quantity excreted in 24-hour urine (μg/24 h), and 15 reported creatinine adjusted values. The meta-analyses show increased levels of 8-epi-PGF_2α in current smokers compared with nonsmokers (mean difference = 0.16, 95% confidence interval [95%CI]: 0.14–0.19 μg/24 h with inconsistency statistic [I²] = 98%; mean difference = 172.38, 95%CI: 152.75–192.01 pg/mg creatinine with I² = 89%, respectively). There were too few publications to perform a meta-analysis assessing the effects of smoking cessation on 8-epi-PGF_2α levels.

Conclusions

Due to the high heterogeneity among the studies included in these meta-analyses, it is difficult to generalize the results; however, our study indicates increased levels of 8-epi-PGF_2α and therefore increased oxidative stress in smokers compared with nonsmokers. More studies are still needed to assess if 8-epi-PGF_2α levels are reversible after cessation.

Quantification of eicosanoids and their metabolites in biological matrices: a review

The quantification of eicosanoids and their metabolites in biological samples remain an analytical challenge, even though a number of methodologies/techniques have been developed. The major difficulties encountered are related to the oxidation of eicosanoids and their low quantities in biological matrices. Among the known methodologies, liquid chromatography-mass spectrometry (LC-MS/MS) is the standard method for eicosanoid quantification in biological samples. Recently advances have improved the ability to identify and simultaneous quantitate eicosanoids in biological matrices. The present article reviews the quantitative analysis of eicosanoids in different biological matrices by LC and ultra performance liquid chromatography (UPLC)-MS/MS and discusses important aspects to be considered during the collection, sample preparation and the generation of calibration curves required for eicosanoid analysis.

Metal exposure and oxidative stress markers in pregnant Navajo Birth Cohort Study participants

Contamination of soil and water by waste from abandoned uranium mines has led to chronic exposures to metal mixtures in Native American communities. Our previous work demonstrated that community exposures to mine waste increase the likelihood of developing cardiovascular disease, as well as the likelihood of developing multiple chronic diseases including diabetes, hypertension and kidney disease. Exposure to various environmental metals is associated with elevated oxidative stress, which is considered a contributor to these and other chronic disease states. The purpose of the current research was to assess potential associations between exposure to uranium and arsenic and evidence for increased oxidative stress as measured by urinary F₂ -isoprostanes in pregnant women enrolled in the Navajo Birth Cohort Study. The current study also included an analysis of zinc as a potential mediator of oxidative stress in the study population. Urinary arsenic and uranium, serum zinc and urinary F₂ -isoprostanes were measured for each study participant at enrollment. Study participants were pregnant women with median age of 26.8; 18.9% were enrolled in the 1st trimester, 44.7% were enrolled in the 2nd trimester, and 36.4% were enrolled in the 3^rd trimester. Median urinary metal levels were 5.5 and 0.016 µg/g creatinine for arsenic and uranium, respectively. Multivariable regression analysis indicated a significant association between arsenic exposure and the lipid peroxidation product 8-iso-prostaglandin F_2α, controlling for zinc and trimester. No associations were detected with uranium despite evidence that levels were in the Navajo Birth Cohort samples were 2.3 times the median reported for women in the National Health and Nutrition Examination Survey (2011-12). Zinc was not found to have any causal mediation of the effects of the other metals on oxidative stress. The current work is consistent with other studies that have detected an association between arsenic and elevated oxidative stress. In contrast to arsenic, uranium did not appear to increase oxidative stress response in this study population. These findings are relevant to assessing the potential human impact of chronic exposure to mixed metal waste from abandoned uranium mines.

Elevated plasma 8-iso-prostaglandin F2α levels in human smokers originate primarily from enzymatic instead of non-enzymatic lipid peroxidation

It is widely accepted that free radicals in tobacco smoke lead to oxidative stress and generate the popular lipid peroxidation biomarker 8-iso-prostaglandin F2α (8-iso-PGF2α). However, 8-iso-PGF2α can simultaneously be produced in vivo by the prostaglandin-endoperoxide synthases (PGHS) induced by inflammation. This inflammation-dependent mechanism has never been considered as a source of elevated 8-iso-PGF2α in tobacco smokers. The goal of this study is to quantify the distribution of chemical- and PGHS-dependent 8-iso-PGF2α formation in the plasma of tobacco smokers and non-smokers. The influences of gender and hormonal contraceptive use were accounted for. The distribution was determined by measuring the 8-iso-PGF2α/prostaglandin F2α (PGF2α) ratio. When comparing smokers (n = 28) against non-smokers (n = 30), there was a statistically significant increase in the 8-iso-PGF2α concentration. The source of this increased 8-iso-PGF2α was primarily from PGHS. When stratifying for gender, the increase in 8-iso-PGF2α in male smokers (n = 9) was primarily from PGHS. Interestingly, female smokers on hormonal contraceptives had increased 8-iso-PGF2α in both pathways, whereas those not on hormonal contraceptives did not have increased 8-iso-PGF2α. In conclusion, increased plasma 8-iso-PGF2α in tobacco smokers has complex origins, with PGHS-dependent formation as the primary source. Accounting for both pathways provides a definitive measurement of both oxidative stress and inflammation.

Isoprostanes, neuroprostanes and phytoprostanes: An overview of 25years of research in chemistry and biology

Since the beginning of the 1990's diverse types of metabolites originating from polyunsaturated fatty acids, formed under autooxidative conditions were discovered. Known as prostaglandin isomers (or isoprostanoids) originating from arachidonic acid, neuroprostanes from docosahexaenoic acid, and phytoprostanes from α-linolenic acid proved to be prevalent in biology. The syntheses of these compounds by organic chemists and the development of sophisticated mass spectrometry methods has boosted our understanding of the isoprostanoid biology. In recent years, it has become accepted that these molecules not only serve as markers of oxidative damage but also exhibit a wide range of bioactivities. In addition, isoprostanoids have emerged as indicators of oxidative stress in humans and their environment. This review explores in detail the isoprostanoid chemistry and biology that has been achieved in the past three decades.

Oxidative Stress and Breast Cancer Risk in Premenopausal Women

BACKGROUND

Detrimental effects of oxidative stress are widely recognized, but induction of apoptosis and senescence may also have benefits for cancer prevention. Recent studies suggest oxidative stress may be associated with lower breast cancer risk before menopause.

METHODS

We conducted a nested case-control study (N = 457 cases, 910 controls) within the NIEHS Sister Study cohort of 50,884 women. Premenopausal women ages 35-54 were eligible for selection. We matched controls 2:1 to cases on age and enrollment year and were breast cancer-free at the time of the corresponding case's diagnosis. Oxidative stress was measured by urinary F2-isoprostane and metabolite (15-F2t-isoprostane-M) concentrations. Odds ratios (OR) and 95% confidence intervals (CIs) were calculated with multivariable conditional logistic regression.

RESULTS

After multivariable adjustment for body mass index (BMI) and other potential confounders, the OR for breast cancer comparing the >90th (≥2.94 ng/mgCr) to <25th percentile (1.01 ng/mgCr) was 1.1 (CI: 0.65, 1.7) for F2-isoprostane and 0.70 (CI: 0.43, 1.1) for the metabolite. Higher metabolite concentrations were associated with lower breast cancer risk among women who were also premenopausal (353 cases, OR: 0.59, CI: 0.34, 1.0) or <46 years (82 cases, OR: 0.15, CI: 0.06, 0.42) at diagnosis. ORs for the metabolite and breast cancer were inverse among women with BMI 18.5-24.9 kg/m (OR: 0.47, CI: 0.18, 1.2, 208 cases) and >30 kg/m (OR: 0.71, CI: 0.30, 1.7, 107 cases), but not among women with BMI 25-29.9 kg/m (OR: 0.98, CI: 0.39, 2.5, 138 cases).

CONCLUSIONS

Together with other studies, our results support a possible inverse association between oxidative stress and premenopausal breast cancer risk.

Increased static and decreased capacity oxidation-reduction potentials in plasma are predictive of metabolic syndrome

Electric conductivity in plasma is the balance between oxidized and reduced molecules (static Oxidation-Reduction Potential, sORP) and the amount of readily oxidizable molecules (capacity ORP, cORP). Adults with metabolic syndrome (MetS) have increased inflammation, dyslipidemia and oxidative stress; therefore, participants with MetS were hypothesized to have higher plasma sORP and lower cORP than those measures in healthy adults. Heparin-anticoagulated plasma from healthy and age- and gender-matched individuals with MetS (BMI: 22.6±0.7 vs. 37.7±3.0 kg/m², respectively) was collected in the fasting state at 0, 24, 48, and 72 h during each of four separate interventions in a clinical trial. At baseline, plasma sORP was 12.4% higher (P=0.007), while cORP values were less than half (41.1%, P=0.001) in those with MetS compared with healthy participants. An sORP >140 mV detected MetS with 90% sensitivity and 80% specificity, while a cORP <0.50 μC detected MetS with 80% sensitivity and 100% specificity. sORP and cORP values in participants with MetS compared with healthy adults were linked to differences in waist circumference and BMI; in plasma markers of dyslipidemia (triglycerides, HDL-cholesterol, and oxidized LDL-cholesterol) and inflammation (C-reactive protein, IL-10); as well as with urinary markers of lipid peroxidation (e.g., 2,3-dinor-5,6-dihydro-8-iso-PGF_2α; 2,3-dinor-8-iso-PGF_2α). Higher sORP values are a robust indicator of metabolic stress, while lower cORP values act as an indicator of decreased metabolic resilience.

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Metabolic syndrome (MetS) adults have increased inflammation and oxidative stress.

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Plasma static (sORP) and capacity oxidation-reduction potentials (cORP) are easily measured.

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MetS sORP and cORP were linked to dyslipidemia, inflammation and oxidative damage.

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Higher sORP indicates stress; lower cORP indicates decreased resilience.

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sORP >140.0 mV or cORP <0.50 μC predicted MetS.

Longitudinal Impact of Smoking and Smoking Cessation on Inflammatory Markers of Cardiovascular Disease Risk

OBJECTIVE

To evaluate longitudinal changes in 6 inflammatory markers that predict cardiovascular disease events among smokers making a quit attempt and to characterize their cross-sectional associations between smoking and smoking heaviness.

APPROACH AND RESULTS

In a longitudinal cohort study of contemporary smokers (n=1652), we evaluated (1) independent associations of smoking heaviness markers (exhaled carbon monoxide, cigarettes/d, pack-years) with inflammatory markers (C-reactive protein, D-dimer, fibrinogen, urinary F₂ isoprostane:creatinine [F₂:Cr] ratio, white blood cell [WBC] count, myeloperoxidase) and (2) the effects of smoking cessation and continued smoking on these inflammatory markers after 1 year, among the 888 smokers who made an aided quit attempt as part of a randomized comparative effectiveness trial or standard care. There were strong, independent associations between smoking heaviness markers and the F₂:Cr ratio, WBC, and myeloperoxidase (all P_adj<0.001), but not high-sensitivity C-reactive protein, D-dimer, or fibrinogen. Participants were mean (SD) 49.6 years old (11.6), 54% women, 34% non-white, and smoked 16.8 cigarettes/d (8.5) for 27.3 pack-years (18.6). After 1 year, the 344 successful abstainers gained more weight (4.0 [6.0] versus 0.4 [5.7] pounds; P<0.001) and had larger increases in insulin resistance scores (P=0.02) than continuing smokers. Despite these increases, abstainers had significant decreases in F₂:Cr ratio (P<0.001) and WBC counts (P<0.001). Changes in other markers were not related to quitting.

CONCLUSIONS

Smoking heaviness is associated with increased F₂:Cr ratio, myeloperoxidase, and WBC counts. Cessation improves the F₂:Cr ratio and WBC counts independent of weight change, suggesting reduced inflammation related to less oxidant stress.

The isoprostanes--25 years later

Isoprostanes (IsoPs) are prostaglandin-like molecules generated independent of the cyclooxygenase (COX) by the free radical-induced peroxidation of arachidonic acid. The first isoprostane species discovered were isomeric to prostaglandin F2α and were thus termed F2-IsoPs. Since the initial discovery of the F2-IsoPs, IsoPs with differing ring structures have been identified as well as IsoPs from different polyunsaturated fatty acids, including eicosapentaenoic acid and docosahexanenoic acid. The discovery of these molecules in vivo in humans has been a major contribution to the field of lipid oxidation and free radical research over the course of the past 25 years. These molecules have been determined to be both biomarkers and mediators of oxidative stress in numerous disease settings. This review focuses on recent developments in the field with an emphasis on clinical research. Special focus is given to the use of IsoPs as biomarkers in obesity, ischemia-reperfusion injury, the central nervous system, cancer, and genetic disorders. Additionally, attention is paid to diet and lifestyle factors that can affect endogenous levels of IsoPs. This article is part of a Special Issue entitled "Oxygenated metabolism of PUFA: analysis and biological relevance."

Determination of ω-6 and ω-3 PUFA metabolites in human urine samples using UPLC/MS/MS

The ω-6 and ω-3 polyunsaturated fatty acids (PUFAs) such as arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) are the precursors of various bioactive lipid mediators including prostaglandins, thromboxanes, leukotrienes, hydroxyeicosatetraenoic acid, isoprostanes, lipoxins, and resolvins (Rvs). These lipid mediators play important roles in various physiological and pathological processes. The quantitative determination of PUFA metabolites seems necessary for disease research and for developing biomarkers. However, there is a paucity of analytical methods for the quantification of ω-6 and ω-3 PUFA metabolites—the specialized pro-resolving mediators (SPMs) present in the human urine. We developed a method for the quantification of ω-6 and ω-3 PUFA metabolites present in human urine using ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS). The developed method shows good linearity, with a correlation coefficient >0.99 for all of the analytes. The validation results indicate that our method is adequately reliable, accurate, and precise. The method was successfully used to examine urine samples obtained from 43 healthy volunteers. We could identify 20 PUFA metabolites, and this is the first report of the quantitative determination of RvD1, 17(R)-RvD1, 11-dehydro thromboxane B3, RvE2, and 5(S)-HETE in human urine. The urinary 8-iso PGF(2α) and PGE2 levels were significantly higher in the men smokers than in the men nonsmokers (p < 0.05). In this study, we developed an accurate, precise, and novel analytical method for estimating the ω-6 and ω-3 PUFA metabolites, and this is the first report that the SPMs derived from EPA and DHA are present in human urine.

Greater γ-tocopherol status during acute smoking abstinence with nicotine replacement therapy improved vascular endothelial function by decreasing 8-iso-15(S)-prostaglandin F2α

Nicotine replacement therapy (NRT) improves the long-term success rate of smoking cessation, but induces oxidative stress and inflammatory responses that may delay the restoration of vascular endothelial function (VEF). No studies have examined co-therapy of NRT-assisted smoking abstinence with γ-tocopherol (γ-T), a vitamin E form with antioxidant and anti-inflammatory activities, on improvements in VEF. In a randomized, double-blind, placebo-controlled study, healthy smokers (25 ± 1 y old; mean ± SEM) received NRT and abstained from smoking for 24 h with placebo (n = 12) or oral administration of γ-T-rich mixture of tocopherols (γ-TmT; n = 11) that provided 500 mg γ-T. Brachial artery flow-mediated dilation (FMD), and biomarkers of nitric oxide metabolism, antioxidant status, inflammation, and lipid peroxidation [8-iso-prostaglandin F2α stereoisomers (8-iso-15(R)-PGF2α and 8-iso-15(S)-PGF2α)] were measured prior to and after 24 h of smoking abstinence. Smoking abstinence with NRT regardless of γ-TmT similarly decreased urinary naphthol (P < 0.05) without affecting plasma cotinine. γ-TmT increased plasma γ-T by 4-times and the urinary metabolite of γ-T, γ-carboxyethyl-chromanol, by three times. Smoking abstinence with γ-TmT, but not smoking abstinence alone, increased FMD without affecting plasma nitrate/nitrite or the ratio of asymmetric dimethylarginine/arginine. Urinary 8-iso-15(S)-PGF2α decreased only in those receiving γ-TmT and was inversely correlated to FMD (R = -0.43, P < 0.05). Circulating markers of inflammation were unaffected by smoking abstinence or γ-TmT. Short-term NRT-assisted smoking abstinence with γ-TmT, but not NRT-assisted smoking abstinence alone, improved VEF by decreasing 8-iso-15(S)-PGF2α, a vasoconstrictor that was otherwise unaffected by NRT-assisted smoking abstinence.

Non-enzymatic lipid oxidation products in biological systems: assessment of the metabolites from polyunsaturated fatty acids

Metabolites of non-enzymatic lipid peroxidation of polyunsaturated fatty acids notably omega-3 and omega-6 fatty acids have become important biomarkers of lipid products. Especially the arachidonic acid-derived F2-isoprostanes are the classic in vivo biomarker for oxidative stress in biological systems. In recent years other isoprostanes from eicosapentaenoic, docosahexaenoic, adrenic and α-linolenic acids have been evaluated, namely F3-isoprostanes, F4-neuroprostanes, F2-dihomo-isoprostanes and F1-phytoprostanes, respectively. These have been gaining interest as complementary specific biomarkers in human diseases. Refined extraction methods, robust analysis and elucidation of chemical structures have improved the sensitivity of detection in biological tissues and fluids. Previously the main reliable instrumentation for measurement was gas chromatography-mass spectrometry (GC-MS), but now the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and immunological techniques is gaining much attention. In this review, the types of prostanoids generated from non-enzymatic lipid peroxidation of some important omega-3 and omega-6 fatty acids and biological samples that have been determined by GC-MS and LC-MS/MS are discussed.

Lipidomic analysis of polyunsaturated fatty acids and their oxygenated metabolites in plasma by solid-phase extraction followed by LC-MS

The present work describes the development of a robust and sensitive targeted analysis platform for the simultaneous quantification in blood plasma of lipid oxygenated mediators and fatty acids using solid-phase extraction (SPE) and high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). The concurrent analysis of these lipid mediators is challenging because of their instability, differences in solubility, and the frequent occurrence of isobaric forms with similar fragmentation patterns. Results demonstrated that the reduction of SPE temperature to 4 °C is a critical parameter for preserving the hydroperoxy derivatives. Polymeric HLB cartridges increased 40-50 % ARA, EPA, and DHA sensitivity compared to C18 sorbent and also provided higher global performance for most hydroxides and other oxidation products. The proposed method for the two tested mass analyzers yields high sensitivity, good linearity, and reproducibility, with detection limits ranging 0.002-7 ng/mL and global recoveries as high as 85-112 %. However, the additional advantage of the linear ion trap (LIT) mass analyzer working in full scan product ion mode, compared to the triple quadrupole (QqQ) operating in multiple reaction monitoring (MRM), should be noted: the full scan product ion mode provides the full fragmentation spectra of compounds that allowed the discrimination of coeluting isomers and false positive identifications without additional chromatography development. The proposed lipidomic procedure demonstrates a confident, simple, and sensitive method to profile in plasma a wide range of lipid eicosanoid and docosanoid mediators, including innovatively the analysis of hydroperoxy congeners and nonoxidized PUFA precursors.

Antioxidant supplements reduced oxidative stress and stabilized liver function tests but did not reduce inflammation in a randomized controlled trial in obese children and adolescents

Oxidative stress and low-grade systemic inflammation may contribute to the pathogenesis of obesity-induced comorbidities, including nonalcoholic fatty liver disease. Increasing intake of dietary antioxidants might be beneficial, but there are few data in obese children. To examine the effect of antioxidant supplementation on biomarkers of oxidative stress, inflammation, and liver function, we randomly assigned overweight or obese children and adolescents (n = 44; mean ± SD age: 12.7 ± 1.5 y) participating in a lifestyle modification program to a 4-mo intervention with daily antioxidants (vitamin E, 400 IU; vitamin C, 500 mg; selenium, 50 μg) or placebo. We measured anthropometrics, antioxidant status, oxidative stress (F(2)-isoprostanes, F(2)-isoprostane metabolites), inflammation, liver enzymes, fasting insulin and glucose, and lipid profile at baseline and endpoint. There was a significant treatment effect of antioxidant supplementation on antioxidant status [α-tocopherol, β = 23.2 (95% CI: 18.0, 28.4); ascorbic acid, β = 70.6 (95% CI: 51.7, 89.4); selenium, β = 0.07 (95% CI: 0.01, 0.12)] and oxidative stress [8-iso-prostaglandin F2α, β = -0.11 (95% CI: -0.19, -0.02)] but not on any of the inflammatory markers measured. There was a significant treatment effect on alanine aminotransferase [β = -0.13 (95% CI: -0.23, -0.03)], a trend toward a significant effect on aspartate aminotransferase [β = -0.04 (95% CI: -0.09, 0.01)], and no significant effect on γ-glutamyltransferase [β = -0.03 (95% CI: -0.11, 0.06)]. In summary, antioxidant supplementation for 4 mo improved antioxidant-oxidant balance and modestly improved liver function tests; however, it did not reduce markers of systemic inflammation despite significant baseline correlations between oxidative stress and inflammation. The study was registered at clinicaltrials.gov as NCT01316081.

Determination of 8-iso-prostaglandin F(2α) (8-iso-PGF(2α)) in human urine by ultra-performance liquid chromatography-tandem mass spectrometry

A rapid, simple and sensitive method was developed for the determination of 8-iso-PGF2α in urine using ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS); 8-iso-PGF2α-d4 was used as the internal standard (IS). Chromatographic separation was performed using an Acquity BEH C18 column with a mobile phase composition of A: 0.1% acetic acid in methanol:acetonitrile (1:1, v:v) and B: 0.1% acetic acid in water (A:B, 32.5:67.5, v:v). Detection was performed on a triple-quadrupole tandem mass spectrometer using atmospheric pressure chemical ionization (APCI) in negative mode and using multiple reaction monitoring (MRM). The MS/MS ion transitions monitored were m/z 353→193 and 357→197 for 8-iso-PGF2α and IS, respectively. The calibration curve was prepared in PBS buffer because of the presence of endogenous concentrations of analyte in the control matrix; the internal standard successfully correcting for matrix effects. Good linearity was observed over the concentration range of 0.025-20 ng/mL; the method proving to be accurate and reliable was successfully used in support of a pharmacodynamic study in humans.

γ-Tocopherol-rich supplementation additively improves vascular endothelial function during smoking cessation

Oxidative stress and inflammation persist years after smoking cessation thereby limiting the restoration of vascular endothelial function (VEF). Although short-term smoking cessation improves VEF, no studies have examined co-therapy of antioxidants in combination with smoking cessation to improve VEF. We hypothesized that improvements in γ-tocopherol (γ-T) status during smoking cessation would improve VEF beyond that from smoking cessation alone by decreasing oxidative stress and proinflammatory responses. A randomized, double-blind, placebo-controlled study was conducted in otherwise healthy smokers (22 ± 1 years; mean ± SEM) who quit smoking for 7 days with placebo (n=14) or γ-T-rich supplementation (n=16; 500 mg γ-T/day). Brachial artery flow-mediated dilation (FMD), cotinine, and biomarkers of antioxidant status, oxidative stress, and inflammation were measured before and after 7 days of smoking cessation. Smoking cessation regardless of supplementation similarly decreased plasma cotinine, whereas γ-T-rich supplementation increased plasma γ-T by seven times and its urinary metabolite γ-carboxyethyl hydroxychroman by nine times (P<0.05). Smoking cessation with γ-T-rich supplementation increased FMD responses by 1.3% (P<0.05) beyond smoking cessation alone (4.1 ± 0.6% vs 2.8 ± 0.3%; mean ± SEM). Although plasma malondialdehyde decreased similarly in both groups (P<0.05), plasma oxidized LDL and urinary F2-isoprostanes were unaffected by smoking cessation or γ-T-rich supplementation. Plasma TNF-α and myeloperoxidase decreased (P<0.05) only in those receiving γ-T-rich supplements and these were inversely related to FMD (P<0.05; R=-0.46 and -0.37, respectively). These findings demonstrate that short-term γ-T-rich supplementation in combination with smoking cessation improved VEF beyond that from smoking cessation alone in young smokers, probably by decreasing the proinflammatory mediators TNF-α and myeloperoxidase.

Concentrations of urinary 8-hydroxy-2'-deoxyguanosine and 8-isoprostane in women exposed to woodsmoke in a cookstove intervention study in San Marcos, Peru

Nearly half of the world's population is exposed to household air pollution (HAP) due to long hours spent in close proximity to unvented cooking fires. The effect of woodsmoke exposure on oxidative stress was examined by investigating the association between woodsmoke exposure and biomarkers of DNA oxidation (8-hydroxy-2'-deoxyguanosine [8-OHdG]) and lipid peroxidation (8-isoprostane) among control and intervention stove users. HAP exposure assessment was conducted within the framework of a community-randomized controlled trial of 51 communities in San Marcos Province, Cajamarca Region, Peru. The first morning urine voids after 48h HAP exposure assessment from a subset of 45 control and 39 intervention stove users were analyzed for 8-OHdG and 8-isoprostane. General linear models and correlation analyses were performed. Urinary oxidative stress biomarkers ranged from 11.2 to 2270.0μg/g creatinine (median: 132.6μg/g creatinine) for 8-OHdG and from 0.1 to 4.5μg/g creatinine (median: 0.8μg/g creatinine) for 8-isoprostane among all study subjects (n=84). After controlling for the effects of traffic in the community and eating food exposed to fire among all subjects, cooking time was weakly, but positively associated with urinary 8-OHdG (r=0.29, p=0.01, n=80). Subjects' real-time personal CO exposures were negatively associated with 8-OHdG, particularly the maximum 30-second CO exposure during the sampling period (r=-0.32, p=0.001, n=73). 48h time integrated personal PM2.5 was negatively, but marginally associated with urinary 8-isoprostane (r=-0.21, p=0.09, n=69) after controlling for the effect of distance of homes to the road. Urinary 8-isoprostane levels reported in the available literature are comparable to results found in the current study. However there were relatively high levels of urinary 8-OHdG compared to data in the available literature for 8-OHdG excretion. Results suggest a sustained systemic oxidative stress among these Peruvian women chronically exposed to wood smoke.

Simultaneous quantification of F2-isoprostanes and prostaglandins in human urine by liquid chromatography tandem-mass spectrometry

A specific and sensitive LC-MS/MS method for analysis of F(2)-isoprostanes (F(2)-IsoPs) and prostaglandins (PGs) in urine was developed and validated to examine the levels of F(2)-IsoPs and prostaglandin F(2α) (PGF(2α)), in human urine in patients undergoing cardiac surgery. The rapid extraction for F(2)-IsoPs and PGs from urine was achieved using a polymeric weak anion solid phase extraction cartridge. The base-line separation of 8-iso-PGF(2α), 8-iso-15(R)-PGF(2α), PGF(2α), and 15(R)-PGF(2α) was carried out on a Hydro-RP column (250mm×2.0mm i.d., Phenomenex, CA) using a linear gradient of methanol:acetonitrile (1:1, v/v) in 0.1% formic acid at a flow rate of 0.2mL/min. The method was proved to be accurate and precise for simultaneous quantification of each analyte over a linear dynamic range of 0.05-50ng/mL with correlation coefficients greater than 0.99. The intra-day and inter-day assay precision at the lowest quality control (0.07ng/mL) level were less than 17%. The mean extraction recoveries of F(2)-IsoPs and PGs were in a range of 79-100%. In applications of this method to patients undergoing cardiac surgery, post-surgery urinary concentrations of 8-iso-PGF(2α) increased significantly in patients (n=14) who did not develop acute kidney (AKI) (pre-surgery 0.344±0.039 vs. post-surgery 0.682±0.094ng/mg creatinine, p<0.01), whereas there was no significant change in this isoprostane in the patients (n=4) who developed AKI (pre-surgery 0.298±0.062 vs. post-surgery 0.383±0.117ng/mg creatinine, NS). Therefore, the method is suitable for the analysis of individual F(2)-IsoPs and PGF(2α)'s in both clinical and research studies.

Impact of ramadan intermittent fasting on oxidative stress measured by urinary 15-f(2t)-isoprostane

Fasting and caloric restriction have been associated with reduced incidence of chronic diseases and cancers. These effects have been attributed to reduced oxidative stress. Since Ramadan intermittent fasting (RIF) has been associated with reduced caloric intake, it was hypothesized that RIF would alleviate oxidative stress in healthy volunteers. The study was designed to elucidate the impact of RIF on oxidative stress measured by 15-F_2t-Isoprostane (15FIP). Fifty healthy subjects (23 men and 27 women) who intended to fast Ramadan were recruited. Urine and serum sampling and anthropometric and dietary assessments were conducted one week before Ramadan (T0), at the end of the third week of Ramadan (T1), and one month after Ramadan (T2). Biochemical measurements included urinary 15FIP, creatinine, and hematological indices. Results revealed that the urinary level of 15FIP measured at T0 was normal, while they showed a significantly (P < 0.05) higher level when measured at T1 concomitant with a significant (P < 0.05) increase in the body weight and total body fat percent. In conclusion, results suggest that increased body weight is associated with increased lipid peroxidation and oxidative stress, and the impact of RIF on oxidative stress is mediated by the changes in body weight at the end of the month.

An eicosanoid-centric view of atherothrombotic risk factors

Cardiovascular disease is the foremost cause of morbidity and mortality in the Western world. Atherosclerosis followed by thrombosis (atherothrombosis) is the pathological process underlying most myocardial, cerebral, and peripheral vascular events. Atherothrombosis is a complex and heterogeneous inflammatory process that involves interactions between many cell types (including vascular smooth muscle cells, endothelial cells, macrophages, and platelets) and processes (including migration, proliferation, and activation). Despite a wealth of knowledge from many recent studies using knockout mouse and human genetic studies (GWAS and candidate approach) identifying genes and proteins directly involved in these processes, traditional cardiovascular risk factors (hyperlipidemia, hypertension, smoking, diabetes mellitus, sex, and age) remain the most useful predictor of disease. Eicosanoids (20 carbon polyunsaturated fatty acid derivatives of arachidonic acid and other essential fatty acids) are emerging as important regulators of cardiovascular disease processes. Drugs indirectly modulating these signals, including COX-1/COX-2 inhibitors, have proven to play major roles in the atherothrombotic process. However, the complexity of their roles and regulation by opposing eicosanoid signaling, have contributed to the lack of therapies directed at the eicosanoid receptors themselves. This is likely to change, as our understanding of the structure, signaling, and function of the eicosanoid receptors improves. Indeed, a major advance is emerging from the characterization of dysfunctional naturally occurring mutations of the eicosanoid receptors. In light of the proven and continuing importance of risk factors, we have elected to focus on the relationship between eicosanoids and cardiovascular risk factors.

A ultra-pressure liquid chromatography/triple quadrupole tandem mass spectrometry method for the analysis of 13 eicosanoids in human urine and quantitative 24 hour values in healthy volunteers in a controlled constant diet

RATIONALE

Isoprostanes (IsoPs) are a series of prostaglandin (PG)-like compounds formed non-enzymatically through free-radical-induced peroxidation of arachidonic acid. They are considered as 'gold-standard' biomarkers for oxidative stress, in general, and lipid peroxidation, in particular.

METHODS

A new qualitative and quantitative analytical method for the determination of 13 eicosanoids in human urine using solid-phase extraction (SPE) and ultra-pressure liquid chromatography coupled to tandem mass spectrometry (UPLC/MS/MS) has been developed. The SPE was optimized by comparison of the extraction efficiency and recoveries of three distinct cartridges: Strata X-AW, C18 Sep-Pak, and Oasis HLB. The UPLC/MS/MS approach in the multiple reaction monitoring (MRM) mode was developed using negative electrospray ionization (ESI).

RESULTS

The validated method provides a high-throughput assay with an adequate linearity from 0.16 to 330 ng mL(-1). The limit of detection (LOD) and limit of quantification (LOQ) for each analyte showed low intervals (0.021-0.64 ng mL(-1) and 0.042-1.28 ng mL(-1), respectively). Urinary IsoPs were determined in 24 healthy volunteers and ranged from 685 to 3480 ng 24 h(-1) and from 864 to 7511 ng 24 h(-1) in urine from women and men, respectively.

CONCLUSIONS

This analytical method could constitute a useful tool for the determination of oxidative stress biomarkers in clinical studies in which IsoPs may evidence early pathological conditions, as suggested by the determination of the baseline IsoPs content in human urine, since it improves upon the detection capacity of previously described methods. The quantity of IsoPs excreted in urine was higher than that found in previous reports due to the total hydrolysis of the conjugated forms.

A simple and robust UPLC-SRM/MS method to quantify urinary eicosanoids

Eicosanoids are key mediators and regulators of inflammation and oxidative stress often used as biomarkers for diseases and pathological conditions such as cardiovascular and pulmonary diseases and cancer. Analytically, comprehensive and robust quantification of different eicosanoid species in a multi-method approach is problematic because most of these compounds are relatively unstable and may differ in their chemical properties. Here we describe a novel ultra-performance liquid chromatography-selected reaction monitoring mass spectroscopy (UPLC-SRM/MS) method for simultaneous quantification of key urinary eicosanoids, including the prostaglandins (PG) tetranor PGE-M, 8-iso-, and 2,3-dinor-8-iso-PGF(2α); the thromboxanes (TXs) 11-dehydro- and 2,3-dinor-TXB₂; leukotriene E₄; and 12-hydroxyeicosatetraenoic acid. In contrast to previous methods, which used time-consuming and complex solid phase extraction, we prepared samples with a simple liquid/liquid extraction procedure. Because collision-induced dissociation produced characteristic product ions for all analytes, no derivatization step for SRM/MS analysis was necessary. Analytes were separated with a short UPLC reversed-phase column (1.7 µm particles), allowing shorter run times than conventional HPLC columns. The method was validated and applied to human urine samples showing excellent precision, accuracy, detection limits, and robustness. In summary, the developed method allows robust and sensitive profiling of urinary eicosanoid species, making it a useful and valuable tool for biomarker profiling in clinical/toxicological studies.

Using biomarkers in sewage to monitor community-wide human health: isoprostanes as conceptual prototype

Timely assessment of the aggregate health of small-area human populations is essential for guiding the optimal investment of resources needed for preventing, avoiding, controlling, or mitigating exposure risks. Seeking those interventions yielding the greatest benefit with respect to allocation of resources is essential for making progress toward community sustainability, promoting social justice, and maintaining or improving health and well-being. More efficient approaches are needed for revealing cause-effect linkages between environmental stressors and human health and for measuring overall aggregate health of small-area populations. A new concept is presented--community health assessment via Sewage Chemical Information Mining (SCIM)--for quickly gauging overall, aggregate health status or trends for entire small-area populations. The approach--BioSCIM--would monitor raw sewage for specific biomarkers broadly associated with human disease, stress, or health. A wealth of untapped chemical information resides in raw sewage, a portion comprising human biomarkers of exposure and effects. BioSCIM holds potential for capitalizing on the presence of biomarkers in sewage for accomplishing any number of objectives. One of the many potential applications of BioSCIM could use various biomarkers of stress resulting from the collective excretion from all individuals in a local population. A prototype example is presented using a class of biomarkers that measures collective, systemic oxidative stress--the isoprostanes (prostaglandin-like free-radical catalyzed oxidation products from certain polyunsaturated fatty acids). Sampling and analysis of raw sewage hold great potential for quickly determining aggregate biomarker levels for entire communities. Presented are the basic principles of BioSCIM, together with its anticipated limitations, challenges, and potential applications in assessing community-wide health. Community health assessment via BioSCIM could allow rapid assessments and intercomparisons of health status among distinct populations, revealing hidden or emerging trends or disparities and aiding in evaluating correlations (or hypotheses) between stressor exposures and disease.

Dried blood spot (DBS) sample collection for determination of the oxidative stress biomarker 8-epi-PGF(2α) in humans using liquid chromatography/tandem mass spectrometry

RATIONALE

F2-isoprostanes are a series of prostaglandin F2-like compounds that are formed by free-radical-catalyzed peroxidation of arachidonic acid (ARA). Several F2-isoprostanes, but in particular 8-epi-PGF(2α), are widely used as oxidative stress biomarkers. In this study we have developed an analytical tool for finger-tip blood sampling and analysis of 8-epi-PGF(2α) from dried blood spots (DBS).

METHODS

We have applied solid-phase extraction (SPE) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the extraction, separation and detection of 8-epi-PGF(2α) in DBS and have studied the stability of this marker using the DBS collection platform.

RESULTS

The mass limit of detection (mLOD) for 8-epi-PGF(2α) extracted from DBS samples was 1.5 pg while the concentration limit of detection (cLOD) and concentration limit of quantitation (cLOQ) were 6 pg/mL and 18 pg/mL, respectively. All values based on triplicate analysis. Sufficient stability of 8-epi-PGF(2α) in DBS was achieved by preconditioning DBS paper with vitamin E and BHT.

CONCLUSIONS

The developed method is sensitive, specific, robust, efficient, and can accurately measure endogenous concentrations of 8-epi-PGF(2α) in DBS. Thus, it offers an analytical approach to measure 8-epi-PGF(2α) by a novel sample collection technique that is less invasive and costly than conventional techniques.

Inducible nitric oxide synthase provides protection against injury-induced thrombosis in female mice

Nitric oxide (NO) is an important vasoactive molecule produced by three NO synthase (NOS) enzymes: neuronal (nNOS), inducible (iNOS), and endothelial NOS (eNOS). While eNOS contributes to blood vessel dilation that protects against the development of hypertension, iNOS has been primarily implicated as a disease-promoting isoform during atherogenesis. Despite this, iNOS may play a physiological role via the modulation of cyclooxygenase and thromboregulatory eicosanoid production. Herein, we examined the role of iNOS in a murine model of thrombosis. Blood flow was measured in carotid arteries of male and female wild-type (WT) and iNOS-deficient mice following ferric chloride-induced thrombosis. Female WT mice were more resistant to thrombotic occlusion than male counterparts but became more susceptible upon iNOS deletion. In contrast, male mice (with and without iNOS deletion) were equally susceptible to thrombosis. Deletion of iNOS was not associated with a change in the balance of thromboxane A(2) (TxA(2)) or antithrombotic prostacyclin (PGI(2)). Compared with male counterparts, female WT mice exhibited increased urinary nitrite and nitrate levels and enhanced ex vivo induction of iNOS in hearts and aortas. Our findings suggest that iNOS-derived NO in female WT mice may attenuate the effects of vascular injury. Thus, although iNOS is detrimental during atherogenesis, physiological iNOS levels may contribute to providing protection against thrombotic occlusion, a phenomenon that may be enhanced in female mice.

Determinants of oxidative stress related to gender: relevance of age and smoking habit

BACKGROUND

Magnitude and major causes of oxidative stress may be different between sexes, although limitedly addressed in clinical studies with controversial results. The present study aimed to determine whether any gender-related difference exists concerning oxidative stress in a population of 332 subjects of both sexes, in a wide age range, with and without cigarette smoking habit.

METHODS

The Oxidative-INDEX was calculated after evaluation of serum hydroperoxides (ROMs) and total antioxidant capacity (OXY) by means of commercial kits (d-ROMs and Oxy-adsorbent Tests, Diacron, Italy) subtracting the OXY standardized variable from the ROMs standardized variable.

RESULTS

The Oxidative-INDEX resulted higher in women with respect to men (p<0.001), in smokers (p<0.01) than in non-smokers, and correlated with cigarette number (p<0.01), age (p<0.001), and post-menopausal status (p<0.001). The multivariate analysis identified age, high blood pressure, and smoking habit as factors independently associated with the Oxidative-INDEX in men, whereas cigarette smoking and age represented the independent risk factors for an elevated oxidative stress status in women.

CONCLUSIONS

Gender-based differences in oxidative stress levels may provide a biochemical basis for the epidemiologic differences in the disease susceptibility between sexes, and suggest different strategies for risk assessment, diagnosis, and treatment specifically targeted to men and women.