The isoprostanes: their quantification as an index of oxidant stress status in vivo

Drug development and novel therapeutics to ensure a personalized approach in the treatment of systemic sclerosis

INTRODUCTION

Systemic sclerosis (SSc) is a systemic disease encompassing autoimmunity, vasculopathy, and fibrosis. SSc is still burdened by high mortality and morbidity rates. Recent advances in understanding the pathogenesis of SSc have identified novel potential therapeutic targets. Several clinical trials have been subsequently designed to evaluate the efficacy of a number of new drugs. The aim of this review is to provide clinicians with useful information about these novel molecules.

AREA COVERED

In this narrative review, we summarize the available evidence regarding the most promising targeted therapies currently under investigation for the treatment of SSc. These medications include kinase inhibitors, B-cell depleting agents, and interleukin inhibitors.

EXPERT OPINION

Over the next five years, several new, targeted drugs will be introduced in clinical practice for the treatment of SSc. Such pharmacological agents will expand the existing pharmacopoeia and enable a more personalized and effective approach to patients with SSc. Thus, it will not only possible to target a specific disease domain, but also different stages of the disease.

GABA content and an antioxidant profile positively correlated with the anticonvulsive activity of Microcos paniculata in acute seizure mice

This study evaluated the effects of different parts of M. paniculata (MP) extracts on convulsions and antioxidant activities in mice. Six polyphenolic compounds were identified, where epicatechin and quercetin have been identified in the highest amounts (23.01 and 32.23 mg/100 g of dry MP extract, respectively) in MP leaf and stem extracts, using Ultra Performance Liquid Chromatography. 7-day oral administration of MP at doses of 100, 200, and 400 mg/kg body weight (BW) significantly reduced convulsions and reduced mortality rates compared with seizure inducer groups. Antioxidant potentials were measured by superoxide dismutase (SOD), catalase (CAT), thiobarbituric acid reactive substances (TBARS), and reduced glutathione (GSH) content in whole-brain homogenates. Gamma-aminobutyric acid (GABA) levels significantly increased in leaves and stem-treated groups, suggesting that MP leaves and stems have potent antioxidant properties that can attenuate convulsions by modulating the GABAergic system and antioxidant activities.

Dietary antioxidant intake is inversely associated with 2,3-dinor oxylipin metabolites, the major excreted oxylipins in overweight and obese subjects

Cardiometabolic disease risk factors, including obesity, insulin resistance, high blood pressure, and dyslipidemia, are associated with elevated oxidative stress biomarkers like oxylipins. Increased adiposity by itself induces various isomers of this oxidized lipid family, while dietary polyphenols show benefits in its regulation. Previously, we showed that specific co-abundant microorganisms characterized the gut microbiota of Colombians and associated differentially with diet, lifestyle, obesity, and cardiometabolic health status, which led us to hypothesize that urinary oxylipins would reflect the intensity of oxidative metabolism linked to gut microbiota dysbiosis. Thus, we selected a convenience sample of 105 participants (age: 40.2 ± 11.9 years, 47.6% women), grouped according to microbiota, cardiometabolic health status, and body mass index (BMI); and evaluated 33 urinary oxylipins by HPLC-QqQ-MS/MS (e.g., isoprostanes, prostaglandins, and metabolites), paired with anthropometry and blood chemistry information and dietary antioxidants estimated from a 24-h food recall. In general, oxylipins did not show differences among individuals who differed in gut microbiota. While the unmetabolized oxylipin levels were not associated with BMI, the total content of oxylipin metabolites was highest in obese and cardiometabolically abnormal subjects (e.g., insulin resistant), mainly by prostaglandin-D (2,3-dinor-11β-PGF_2α) and 15-F_2t-IsoPs (2,3-dinor-15-F_2t-IsoP and 2,3-dinor-15-epi-15-F_2t-IsoP) metabolites. The total polyphenol intake in this cohort was 1070 ± 627 mg/day. After adjusting for body weight, the polyphenol intake was significantly higher in lean than overweight and showed an inverse association with dinor-oxylipin levels in principal component analysis. These results suggest that the 2,3-dinor-oxylipins could be more specific biomarkers associated with BMI than their parent oxylipins and that are sensitive to be regulated by dietary antioxidants.

Associations of dietary, lifestyle, other participant characteristics, and oxidative balance scores with plasma F2-isoprostanes concentrations in a pooled cross-sectional study

PURPOSE

Plasma F₂-isoprostanes (FiP) concentration, a reliably measured, valid, systemic oxidative stress biomarker, has been associated with multiple health-related outcomes; however, associations of most individual dietary and lifestyle exposures with FiP are unclear, and there is no reported oxidative balance score (OBS) comprising multiple dietary and/or lifestyle components weighted by their associations with FiP.

METHODS

To investigate cross-sectional associations of dietary and lifestyle characteristics with plasma FiP concentrations, we used multivariable general linear models to compare adjusted mean FiP concentrations across categories of dietary nutrient and whole-food intakes and lifestyle characteristics in two pooled cross-sectional studies (n = 386). We also developed equal-weight and weighted OBS (nutrient- and foods-based dietary OBS, lifestyle OBS, and total OBS), and compared adjusted mean FiP concentrations across OBS tertiles.

RESULTS

Among men and women combined, adjusted mean FiP concentrations were statistically significantly, proportionately 28.1% higher among those who were obese relative to those who were normal weight; among those in the highest relative to the lowest total nutrient intake tertiles, FiP concentrations were statistically significantly lower by 9.8% for carotenes, 13.6% for lutein/zeaxanthin, 10.9% for vitamin C, 12.2% for vitamin E, 11.5% for glucosinolates, and 5% for calcium. Of the various OBS, the weighted OBS that combined total nutrient intakes and lifestyle exposures was most strongly associated with FiP concentrations: among those in the highest relative to the lowest total OBS, mean FiP concentrations were statistically significantly 29.7% lower (P < 0.001).

CONCLUSION

Multiple dietary and lifestyle characteristics, individually, and especially collectively, may contribute to systemic oxidative stress.

Biosynthetic Crossover of 5-Lipoxygenase and Cyclooxygenase-2 Yields 5-Hydroxy-PGE2 and 5-Hydroxy-PGD2

The biosynthetic crossover of 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2) enzymatic activities is a productive pathway to convert arachidonic acid into unique eicosanoids. Here, we show that COX-2 catalysis with 5-LOX derived 5-hydroxy-eicosatetraenoic acid yields the endoperoxide 5-hydroxy-PGH2 that spontaneously rearranges to 5-OH-PGE2 and 5-OH-PGD2, the 5-hydroxy analogs of arachidonic acid derived PGE2 and PGD2. The endoperoxide was identified via its predicted degradation product, 5,12-dihydroxy-heptadecatri-6E,8E,10E-enoic acid, and by SnCl2-mediated reduction to 5-OH-PGF2α. Both 5-OH-PGE2 and 5-OH-PGD2 were unstable and degraded rapidly upon treatment with weak base. This instability hampered detection in biologic samples which was overcome by in situ reduction using NaBH4 to yield the corresponding stable 5-OH-PGF2 diastereomers and enabled detection of 5-OH-PGF2α in activated primary human leukocytes. 5-OH-PGE2 and 5-OH-PGD2 were unable to activate EP and DP prostanoid receptors, suggesting their bioactivity is distinct from PGE2 and PGD2.

Approaches for Reactive Oxygen Species and Oxidative Stress Quantification in Epilepsy

Oxidative stress (OS) and excessive reactive oxygen species (ROS) production have been implicated in many neurological pathologies, including acute seizures and epilepsy. Seizure-induced damage has been demonstrated both in vitro and in several in vivo seizure and epilepsy models by direct determination of ROS, and by measuring indirect markers of OS. In this manuscript, we review the current reliable methods for quantifying ROS-related and OS-related markers in pre-clinical and clinical epilepsy studies. We first provide pieces of evidence for the involvement of different sources of ROS in epilepsy. We then discuss general methods and assays used for the ROS measurements, mainly superoxide anion, hydrogen peroxide, peroxynitrite, and hydroxyl radical in in vitro and in vivo studies. In addition, we discuss the role of these ROS and markers of oxidative injury in acute seizures and epilepsy pre-clinical studies. The indirect detection of secondary products of ROS such as measurements of DNA damage, lipid peroxidation, and protein oxidation will also be discussed. This review also discusses reliable methods for the assessment of ROS, OS markers, and their by-products in epilepsy clinical studies.

Use of integrated biomarker response for evaluating antioxidant stress and DNA damage of earthworms (Eisenia fetida) in decabromodiphenyl ethane-contaminated soil

Decabromodiphenyl ethane (DBDPE) is a new and popular type of brominated flame retardant (BFR) with high bromine content, strong thermal stability, and ultraviolet resistance. To evaluated the potential toxicity of this new BFR to soil ecosystem, different concentrations of DBDPE were used to observe effects on earthworms (Eisenia fetida) in artificial soil. The reactive oxygen species (ROS) contents, activities of antioxidase system and detoxify enzyme, levels of malondialdehyde (MDA), as well as DNA damage in earthworms were measured after exposure to 0, 2.5, 5, 10, and 20 mg/kg DBDPE in artificial soil for 7, 14, 21, and 28 days. The results showed that ROS and MDA content significantly increased for all treatments from days 7-21, followed by a decrease. Throughout the experimental period, SOD, POD, and CAT activities increased. The GST activity was stimulated significantly from days 14-28. Besides, the olive tail moment (OTM) value in all treated groups was significantly higher than that in the control and exhibited a concentration-related and exposure time-related response. This is the first study evaluating the biological toxicity of BFR at different concentrations using an integrated biomarker response index. Our results show that DBDPE has biochemical toxicity on earthworms, which sheds some light on the potential risks of DBDPE in the soil environment and provides a basis for the monitoring and diagnosis of soils contaminated with DBDPE.

Oxidative stress in alcohol-related liver disease

Alcohol consumption is one of the leading causes of the global burden of disease and results in high healthcare and economic costs. Heavy alcohol misuse leads to alcohol-related liver disease, which is responsible for a significant proportion of alcohol-attributable deaths globally. Other than reducing alcohol consumption, there are currently no effective treatments for alcohol-related liver disease. Oxidative stress refers to an imbalance in the production and elimination of reactive oxygen species and antioxidants. It plays important roles in several aspects of alcohol-related liver disease pathogenesis. Here, we review how chronic alcohol use results in oxidative stress through increased metabolism via the cytochrome P450 2E1 system producing reactive oxygen species, acetaldehyde and protein and DNA adducts. These trigger inflammatory signaling pathways within the liver leading to expression of pro-inflammatory mediators causing hepatocyte apoptosis and necrosis. Reactive oxygen species exposure also results in mitochondrial stress within hepatocytes causing structural and functional dysregulation of mitochondria and upregulating apoptotic signaling. There is also evidence that oxidative stress as well as the direct effect of alcohol influences epigenetic regulation. Increased global histone methylation and acetylation and specific histone acetylation inhibits antioxidant responses and promotes expression of key pro-inflammatory genes. This review highlights aspects of the role of oxidative stress in disease pathogenesis that warrant further study including mitochondrial stress and epigenetic regulation. Improved understanding of these processes may identify novel targets for therapy.

Simultaneous angiotensin receptor blockade and glucagon-like peptide-1 receptor activation ameliorate albuminuria in obese insulin-resistant rats

Insulin resistance increases renal oxidant production by upregulating NADPH oxidase 4 (Nox4) expression contributing to oxidative damage and ultimately albuminuria. Inhibition of the renin-angiotensin system (RAS) and activation of glucagon-like peptide-1 (GLP-1) receptor signalling may reverse this effect. However, whether angiotensin receptor type 1 (AT1) blockade and GLP-1 receptor activation improve oxidative damage and albuminuria through different mechanisms is not known. Using insulin-resistant Otsuka Long-Evans Tokushima Fatty (OLETF) rats, we tested the hypothesis that simultaneous blockade of AT1 and activation of GLP-1r additively decrease oxidative damage and urinary albumin excretion (U_alb V) in the following groups: (a) untreated, lean LETO (n = 7), (b) untreated, obese OLETF (n = 9), (c) OLETF + angiotensin receptor blocker (ARB; 10 mg olmesartan/kg/d; n = 9), (d) OLETF + GLP-1 mimetic (EXE; 10 µg exenatide/kg/d; n = 7) and (e) OLETF + ARB +exenatide (Combo; n = 6). Mean kidney Nox4 protein expression and nitrotyrosine (NT) levels were 30% and 46% greater, respectively, in OLETF compared with LETO. Conversely, Nox4 protein expression and NT were reduced to LETO levels in ARB and EXE, and Combo reduced Nox4, NT and 4-hydroxy-2-nonenal levels by 21%, 27% and 27%, respectively. At baseline, U_alb V was nearly double in OLETF compared with LETO and increased to nearly 10-fold greater levels by the end of the study. Whereas ARB (45%) and EXE (55%) individually reduced U_alb V, the combination completely ameliorated the albuminuria. Collectively, these data suggest that AT1 blockade and GLP-1 receptor activation reduce renal oxidative damage similarly during insulin resistance, whereas targeting both signalling pathways provides added benefit in restoring and/or further ameliorating albuminuria in a model of diet-induced obesity.

Urinary Markers of Oxidative Stress in Children with Autism Spectrum Disorder (ASD)

Background: Autism spectrum disorder (ASD) is a developmental disorder characterized by deficits in social interaction, restricted interest and repetitive behavior. Oxidative stress in response to environmental exposure plays a role in virtually every human disease and represents a significant avenue of research into the etiology of ASD. The aim of this study was to explore the diagnostic utility of four urinary biomarkers of oxidative stress. Methods: One hundred and thirty-nine (139) children and adolescents with ASD (89% male, average age = 10.0 years, age range = 2.1 to 18.1 years) and 47 healthy children and adolescents (49% male, average age 9.2, age range = 2.5 to 20.8 years) were recruited for this study. Their urinary 8-OH-dG, 8-isoprostane, dityrosine and hexanoil-lisine were determined by using the ELISA method. Urinary creatinine was determined with the kinetic Jaffee reaction and was used to normalize all biochemical measurements. Non-parametric tests and support vector machines (SVM) with three different kernel functions (linear, radial, polynomial) were used to explore and optimize the multivariate prediction of an ASD diagnosis based on the collected biochemical measurements. The SVM models were first trained using data from a random subset of children and adolescents from the ASD group (n = 70, 90% male, average age = 9.7 years, age range = 2.1 to 17.8 years) and the control group (n = 24, 45.8% male, average age = 9.4 years, age range = 2.5 to 20.8 years) using bootstrapping, with additional synthetic minority over-sampling (SMOTE), which was utilized because of unbalanced data. The computed SVM models were then validated using the remaining data from children and adolescents from the ASD (n = 69, 88% male, average age = 10.2 years, age range = 4.3 to 18.1 years) and the control group (n = 23, 52.2% male, average age = 8.9 years, age range = 2.6 to 16.7 years). Results: Using a non-parametric test, we found a trend showing that the urinary 8-OH-dG concentration was lower in children with ASD compared to the control group (unadjusted p = 0.085). When all four biochemical measurements were combined using SVMs with a radial kernel function, we could predict an ASD diagnosis with a balanced accuracy of 73.4%, thereby accounting for an estimated 20.8% of variance (p < 0.001). The predictive accuracy expressed as the area under the curve (AUC) was solid (95% CI = 0.691-0.908). Using the validation data, we achieved significantly lower rates of classification accuracy as expressed by the balanced accuracy (60.1%), the AUC (95% CI = 0.502-0.781) and the percentage of explained variance (R² = 3.8%). Although the radial SVMs showed less predictive power using the validation data, they do, together with ratings of standardized SVM variable importance, provide some indication that urinary levels of 8-OH-dG and 8-isoprostane are predictive of an ASD diagnosis. Conclusions: Our results indicate that the examined urinary biomarkers in combination may differentiate children with ASD from healthy peers to a significant extent. However, the etiological importance of these findings is difficult to assesses, due to the high-dimensional nature of SVMs and a radial kernel function. Nonetheless, our results show that machine learning methods may provide significant insight into ASD and other disorders that could be related to oxidative stress.

Biomarker responses of earthworms (Eisenia fetida) to soils contaminated with perfluorooctanoic acid

Perfluorooctanoic acid (PFOA) is considered a persistent environmental pollutant. The aim of this study was to assess the potential toxicity of PFOA to earthworms (Eisenia fetida) in artificial soil. The activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and glutathione S-transferase (GST) as well as the contents of malondialdehyde (MDA) were measured after exposure to 0, 5, 10, 20, and 40 mg kg^-1 PFOA in soils for 7, 14, 21, and 28 days. The results showed that SOD activity increased at 14 days and decreased from 21 to 28 days; MDA levels were highest in the treatment with 40 mg kg^-1 PFOA after 28 days of exposure. In contrast, CAT and POD activities increased after 14-21 days of exposure and significantly decreased with long-term exposure (28 days). GST activity increased significantly from 14 to 28 days. Our results indicate that PFOA has biochemical effects on E. fetida, thereby contributing to our understanding of the ecological toxicity of PFOA on soil invertebrates.

The enigma ofin vivooxidative stress assessment: isoprostanes as an emerging target

Oxidative stress is believed to be one of the major factors behind several acute and chronic diseases, and may also be associated with ageing. Excess formation of free radicals in miscellaneous body environment may originate from endogenous response to cell injury, but also from exposure to a number of exogenous toxins. When the antioxidant defence system is overwhelmed, this leads to cell damage. However, the measurement of free radicals or their endproducts is tricky, since these compounds are reactive and short lived, and have diverse characteristics. Specific evidence for the involvement of free radicals in pathological situations has been difficult to obtain, partly owing to shortcomings in earlier described methods for the measurement of oxidative stress. Isoprostanes, which are prostaglandin-like bioactive compounds synthesized in vivo from oxidation of arachidonic acid, independently of cyclooxygenases, are involved in many human diseases, and their measurement therefore offers a way to assess oxidative stress. Elevated levels of F₂-isoprostanes have also been seen in the normal human pregnancy, but their physiological role has not yet been defined. Large amounts of bioactive F₂-isoprostanes are excreted in the urine in normal basal situations, with a wide interindividual variation. Their exact role in the regulation of normal physiological functions, however, needs to be explored further. Current understanding suggests that measurement of F₂-isoprostanes in body fluids provides a reliable analytical tool to study oxidative stress-related diseases and experimental inflammatory conditions, and also in the evaluation of various dietary antioxidants, as well as drugs with radical-scavenging properties. However, assessment of isoprostanes in plasma or urine does not necessarily reflect any specific tissue damage, nor does it provide information on the oxidation of lipids other than arachidonic acid.

Effect of Coenzyme Q10 on Biomarkers of Oxidative Stress and Cardiac Function in Hemodialysis Patients: The CoQ10 Biomarker Trial

BACKGROUND

Oxidative stress is highly prevalent in patients with end-stage renal disease and is linked to excess cardiovascular risk. Identifying therapies that reduce oxidative stress has the potential to improve cardiovascular outcomes in patients undergoing maintenance dialysis.

STUDY DESIGN

Placebo-controlled, 3-arm, double-blind, randomized, clinical trial.

SETTING & PARTICIPANTS

65 patients undergoing thrice-weekly maintenance hemodialysis.

INTERVENTION

Patients were randomly assigned in a 1:1:1 ratio to receive once-daily coenzyme Q₁₀ (CoQ₁₀; 600 or 1,200mg) or matching placebo for 4 months.

OUTCOMES

The primary outcome was plasma oxidative stress, defined as plasma concentration of F₂-isoprotanes. Secondary outcomes included levels of plasma isofurans, levels of cardiac biomarkers, predialysis blood pressure, and safety/tolerability.

MEASUREMENTS

F₂-isoprostanes and isofurans were measured as plasma markers of oxidative stress, and N-terminal pro-brain natriuretic peptide and troponin T were measured as cardiac biomarkers at baseline and 1, 2, and 4 months.

RESULTS

Of 80 randomly assigned patients, 15 were excluded due to not completing at least 1 postbaseline study visit and 65 were included in the primary intention-to-treat analysis. No treatment-related major adverse events occurred. Daily treatment with 1,200mg, but not 600mg, of CoQ₁₀ significantly reduced plasma F₂-isoprostanes concentrations at 4 months compared to placebo (adjusted mean changes of -10.7 [95% CI, -7.1 to -14.3] pg/mL [P<0.001] and -8.3 [95% CI, -5.5 to -11.0] pg/mL [P=0.1], respectively). There were no significant effects of CoQ₁₀ treatment on levels of plasma isofurans, cardiac biomarkers, or predialysis blood pressures.

LIMITATIONS

Study not powered to detect small treatment effects; difference in baseline characteristics among randomized groups.

CONCLUSIONS

In patients undergoing maintenance hemodialysis, daily supplementation with 1,200mg of CoQ₁₀ is safe and results in a reduction in plasma concentrations of F₂-isoprostanes, a marker of oxidative stress. Future studies are needed to determine whether CoQ₁₀ supplementation improves clinical outcomes for patients undergoing maintenance hemodialysis.

Toxicological evaluation of the aqueous stem bark extract of Bridelia ferruginea (Euphorbiaceae) in rodents

Bridelia ferruginea is a woody shrub that grows in the Savannah or rain forests of Africa and has traditionally been used to treat diabetes, arthritis and boils. Despite all these uses, extensive toxicological evaluation has not been carried out. The aim of the present investigation was to evaluate the sub-chronic toxicological effects of the stem bark aqueous extract of Bridelia ferruginea in rats. The lethal dose (LD₅₀) was determined using probit analysis and graded doses of the extract (250–4000 mg/kg) were administered to the animals via oral and intraperitoneal routes and observed for mortality, behavioral changes and signs of toxicity. Sub-chronic toxicity study was carried out at doses of 1 000, 2 000 and 4 000 mg/kg administered daily for 60 days. The animals were sacrificed after 60 days. Blood was collected for biochemical (renal and hepatic), hematological, oxidative stress, sperm and histopathological examinations, using standard methods. LD₅₀ of the extract was estimated as >4 000 mg/kg orally; neither significant visible signs of toxicity nor mortality were observed. There were no significant differences in the animals and organ weights, hematological and biochemical parameters in the treated groups compared to the control group. However, a significant increase (p<0.05) in the level of lipid peroxidation and a significant (p<0.05) decrease in sperm count were observed in the treated animals compared with the control group. The stem-bark aqueous extract of Bridelia ferruginea was found to be relatively safe, though it has the potential to cause lipid peroxidation and damage sperm quality and should thus be used with caution.

Renoprotective effect of the xanthine oxidoreductase inhibitor topiroxostat on adenine-induced renal injury

The aim of the present study was to reveal the effect of a xanthine oxidoreductase (XOR) inhibitor, topiroxostat (Top), compared with another inhibitor, febuxostat (Feb), in an adenine-induced renal injury model. We used human liver-type fatty acid-binding protein (L-FABP) chromosomal transgenic mice, and urinary L-FABP, a biomarker of tubulointerstitial damage, was used to evaluate tubulointerstitial damage. Male transgenic mice ( n = 24) were fed a 0.2% (wt/wt) adenine-containing diet. Two weeks after the start of this diet, renal dysfunction was confirmed, and the mice were divided into the following four groups: the adenine group was given only the diet containing adenine, and the Feb, high-dose Top (Top-H), and low-dose Top (Top-L) groups were given diets containing Feb (3 mg/kg), Top-H (3 mg/kg), and Top-L (1 mg/kg) in addition to adenine for another 2 wk. After withdrawal of the adenine diet, each medication was continued for 2 wk. Serum creatinine levels, the degree of macrophage infiltration, tubulointerstitial damage, renal fibrosis, urinary 15-F2t-isoprostane levels, and renal XOR activity were significantly attenuated in the kidneys of the Feb, Top-L, and Top-H groups compared with the adenine group. Serum creatinine levels in the Top-L and Top-H groups as well as renal XOR in the Top-H group were significantly lower than those in the Feb group. Urinary excretion of L-FABP in both the Top-H and Top-L groups was significantly lower than in the adenine and Feb groups. In conclusion, Top attenuated renal damage in an adenine-induced renal injury model.

Activation of the Thromboxane A2 Receptor by 8-Isoprostane Inhibits the Pro-Angiogenic Effect of Vascular Endothelial Growth Factor in Scleroderma

The pathogenesis of scleroderma (SSc) includes components of autoimmunity, vascular dysfunction, and accumulation of extracellular matrix. 8-isoprostane, an oxidized lipid created by oxidative stress, activates the thromboxane A2 receptor (TXAR) and ROCK pathway. In this study we determined whether the TXAR was activated by 8-isoprostane in SSc endothelial cells (ECs), and whether this pathway inhibited VEGF-induced angiogenesis. Elevated 8-isoprostane was observed in plasma and conditioned media from SSc patients. SSc conditioned media inhibited EC tube formation, while addition of vitamin E, by reducing 8-isoprostane, increased tube formation. VEGF did not induce angiogenesis in SSc ECs, but vitamin E or TXAR inhibition restored its effect. The expression of TXAR, RhoA, and ROCK1/2 were elevated in SSc ECs. ROCK activity and 8-isoprostane-induced ROCK activation were significantly higher in SSc ECs while VEGF had no effect. The hyper-activation of the TXAR leads to inhibition of VEGF-induced angiogenesis, as inhibition of the TXAR pathway results in blockade of 8-isoprostane induced ROCK activation and restoration of VEGF activity. These results suggest that the TXAR pathway plays a crucial role in angiogenesis and that 8-isoprostane is not just a by-product of oxidative stress, but also plays a significant role in the impaired angiogenesis that characterizes SSc.

Role of cellular senescence and NOX4-mediated oxidative stress in systemic sclerosis pathogenesis

Systemic sclerosis (SSc) is a systemic autoimmune disease characterized by progressive fibrosis of skin and numerous internal organs and a severe fibroproliferative vasculopathy resulting frequently in severe disability and high mortality. Although the etiology of SSc is unknown and the detailed mechanisms responsible for the fibrotic process have not been fully elucidated, one important observation from a large US population study was the demonstration of a late onset of SSc with a peak incidence between 45 and 54 years of age in African-American females and between 65 and 74 years of age in white females. Although it is not appropriate to consider SSc as a disease of aging, the possibility that senescence changes in the cellular elements involved in its pathogenesis may play a role has not been thoroughly examined. The process of cellular senescence is extremely complex, and the mechanisms, molecular events, and signaling pathways involved have not been fully elucidated; however, there is strong evidence to support the concept that oxidative stress caused by the excessive generation of reactive oxygen species may be one important mechanism involved. On the other hand, numerous studies have implicated oxidative stress in SSc pathogenesis, thus, suggesting a plausible mechanism in which excessive oxidative stress induces cellular senescence and that the molecular events associated with this complex process play an important role in the fibrotic and fibroproliferative vasculopathy characteristic of SSc. Here, recent studies examining the role of cellular senescence and of oxidative stress in SSc pathogenesis will be reviewed.

Assessing Human Health Risk to Endocrine Disrupting Chemicals: a Focus on Prenatal Exposures and Oxidative Stress

Understanding the health risk posed by endocrine disrupting chemicals (EDCs) is a challenge that is receiving intense attention. The following study criteria should be considered to facilitate risk assessment for exposure to EDCs: 1) characterization of target health outcomes and their mediators, 2) study of exposures in the context of critical periods of development, 3) accurate estimates of human exposures and use of human-relevant exposures in animal studies, and 4) cross-species comparisons. In this commentary, we discuss the importance and relevance of each of these criteria in studying the effects of prenatal exposure to EDCs. Our discussion focuses on oxidative stress as a mediator of EDC-related health effects due to its association with both EDC exposure and health outcomes. Our recent study (Veiga-Lopez et al. 2015)¹ addressed each of the four outlined criteria and demonstrated that prenatal bisphenol-A exposure is associated with oxidative stress, a risk factor for developing diabetes and cardiovascular diseases in adulthood.

The Minnesota Green Tea Trial (MGTT), a randomized controlled trial of the efficacy of green tea extract on biomarkers of breast cancer risk: study rationale, design, methods, and participant characteristics

PURPOSE

The Minnesota Green Tea Trial (MGTT) was a randomized, placebo-controlled, double-blinded trial investigating the effect of daily green tea extract consumption for 12 months on biomarkers of breast cancer risk.

METHODS

Participants were healthy postmenopausal women at high risk of breast cancer due to dense breast tissue with differing catechol-O-methyltransferase (COMT) genotypes. The intervention was a green tea catechin extract containing 843.0 ± 44.0 mg/day epigallocatechin gallate or placebo capsules for 1 year. Annual digital screening mammograms were obtained at baseline and month 12, and fasting blood and 24-h urine samples were provided at baseline and at months 6 and 12. Primary endpoints included changes in percent mammographic density, circulating endogenous sex hormones, and insulin-like growth factor axis proteins; secondary endpoints were changes in urinary estrogens and estrogen metabolites and circulating F2-isoprostanes, a biomarker of oxidative stress.

RESULTS

The MGTT screened more than 100,000 mammograms and randomized 1,075 participants based on treatment (green tea extract vs. placebo), stratified by COMT genotype activity (high COMT vs. low/intermediate COMT genotype activity). A total of 937 women successfully completed the study and 138 dropped out (overall dropout rate = 12.8 %).

CONCLUSIONS

In this paper we report the rationale, design, recruitment, participant characteristics, and methods for biomarker and statistical analyses.

Noninvasive effects measurements for air pollution human studies: methods, analysis, and implications

Human exposure studies, compared with cell and animal models, are heavily relied upon to study the associations between health effects in humans and air pollutant inhalation. Human studies vary in exposure methodology, with some work conducted in controlled settings, whereas other studies are conducted in ambient environments. Human studies can also vary in the health metrics explored, as there exists a myriad of health effect end points commonly measured. In this review, we compiled mini reviews of the most commonly used noninvasive health effect end points that are suitable for panel studies of air pollution, broken into cardiovascular end points, respiratory end points, and biomarkers of effect from biological specimens. Pertinent information regarding each health end point and the suggested methods for mobile collection in the field are assessed. In addition, the clinical implications for each health end point are summarized, along with the factors identified that can modify each measurement. Finally, the important research findings regarding each health end point and air pollutant exposures were reviewed. It appeared that most of the adverse health effects end points explored were found to positively correlate with pollutant levels, although differences in study design, pollutants measured, and study population were found to influence the magnitude of these effects. Thus, this review is intended to act as a guide for researchers interested in conducting human exposure studies of air pollutants while in the field, although there can be a wider application for using these end points in many epidemiological study designs.

Decoding the oxidative stress hypothesis in diabetic embryopathy through proapoptotic kinase signaling

Maternal diabetes-induced birth defects occur in 6-10% of babies born to mothers with pregestational diabetes, representing a significant maternal-fetal health problem. Currently, these congenital malformations represent a significant maternal-fetal medicine issue, but are likely to create an even greater public health threat as 3 million women of reproductive age (19-44 years) have diabetes in the United States alone, and this number is expected to double by 2030. Neural tube defects (NTDs) and congenital heart defects are the most common types of birth defects associated with maternal diabetes. Animal studies have revealed that embryos under hyperglycemic conditions exhibit high levels of oxidative stress resulting from enhanced production of reactive oxygen species and impaired antioxidant capability. Oxidative stress activates a set of proapoptotic kinase signaling intermediates leading to abnormal cell death in the embryonic neural tube, which causes NTD formation. Work in animal models also has revealed that maternal diabetes triggers a series of signaling intermediates: protein kinase C (PKC) isoforms, PKCα, βII and δ; apoptosis signal-regulating kinase 1; c-Jun-N-terminal kinase (JNK)1/2; caspase; and apoptosis. Specifically, maternal diabetes in rodent models activates the proapoptotic unfolded protein response and endoplasmic reticulum (ER) stress. A reciprocal causation between JNK1/2 activation and ER stress exists in diabetic embryopathy. Molecular studies further demonstrate that deletion of the genes for Prkc, Ask1, Jnk1, or Jnk2 abolishes maternal diabetes-induced neural progenitor apoptosis and ameliorates NTD formation. Similar preventive effects are also observed when apoptosis signal-regulating kinase 1, JNK1/2, or ER stress is inhibited. Cell membrane stabilizers and antioxidant supplements are also effective in prevention of diabetes-induced birth defects. Mechanistic studies have revealed important insights into our understanding the cause of diabetic embryopathy and have provided a basis for future interventions against birth defects or other pregnancy complications associated with maternal diabetes. The knowledge of a molecular pathway map identified in animal studies has created unique opportunities to identify molecular targets for therapeutic intervention.

Childhood obesity: immune response and nutritional approaches

Childhood obesity is characterized by a low-grade inflammation status depending on the multicellular release of cytokines, adipokines, and reactive oxygen species. In particular, the imbalance between anti-inflammatory T regulatory cells and inflammatory T helper 17 cells seems to sustain such a phlogistic condition. Alterations of gut microbiota since childhood also contribute to the maintenance of inflammation. Therefore, besides preventive measures and caloric restrictions, dietary intake of natural products endowed with anti-oxidant and anti-inflammatory activities may represent a valid interventional approach for preventing and/or attenuating the pathological consequences of obesity. In this regard, the use of prebiotics, probiotics, polyphenols, polyunsaturated fatty acids, vitamins, and melatonin in human clinical trials will be described.

Seizure-induced oxidative stress in temporal lobe epilepsy

An insult to the brain (such as the first seizure) causes excitotoxicity, neuroinflammation, and production of reactive oxygen/nitrogen species (ROS/RNS). ROS and RNS produced during status epilepticus (SE) overwhelm the mitochondrial natural antioxidant defense mechanism. This leads to mitochondrial dysfunction and damage to the mitochondrial DNA. This in turn affects synthesis of various enzyme complexes that are involved in electron transport chain. Resultant effects that occur during epileptogenesis include lipid peroxidation, reactive gliosis, hippocampal neurodegeneration, reorganization of neural networks, and hypersynchronicity. These factors predispose the brain to spontaneous recurrent seizures (SRS), which ultimately establish into temporal lobe epilepsy (TLE). This review discusses some of these issues. Though antiepileptic drugs (AEDs) are beneficial to control/suppress seizures, their long term usage has been shown to increase ROS/RNS in animal models and human patients. In established TLE, ROS/RNS are shown to be harmful as they can increase the susceptibility to SRS. Further, in this paper, we review briefly the data from animal models and human TLE patients on the adverse effects of antiepileptic medications and the plausible ameliorating effects of antioxidants as an adjunct therapy.

Tunneling in tocopherol-mediated peroxidation of 7-dehydrocholesterol

The peroxidation of 7-dehydrocholesterol (7-DHC), a biosynthetic precursor to vitamin D3 and cholesterol, has been linked to the pathophysiology of Smith-Lemli-Optiz syndrome (SLOS), a devastating human disorder. In SLOS, 7-DHC plasma and tissue levels are elevated because of defects in the enzyme that convert it to cholesterol. α-Tocopherol can mediate the peroxidation of 7-DHC under certain circumstances and this prompted us to investigate the kinetic isotope effect (KIE) during this process. Thus, 9,14-d2-7-DHC was synthesized using a photochemical cyclization of deuterium-reinforced previtamin D3 (retro to its biosynthesis). Subsequently, we carried out co-oxidation of 9,14-h2-25,26,26,26,27,27,27-d7- and 9,14-d2-7-DHC in the presence of α-tocopherol under conditions that favor TMP. By monitoring the products formed from each precursor using mass spectrometry, the KIE for the hydrogen (deuterium) atom removal at C9 was found to be 21 ± 1. This large KIE value indicates that tunneling plays a role in the hydrogen atom transfer step in the tocopherol-mediated peroxidation of 7-DHC.

Sex-specific effect of antenatal betamethasone exposure on renal oxidative stress induced by angiotensins in adult sheep

Prenatal glucocorticoid administration in clinically relevant doses reduces nephron number and renal function in adulthood and is associated with hypertension. Nephron loss in early life may predispose the kidney to other insults later but whether sex influences increases in renal susceptibility is unclear. Therefore, we determined, in male and female adult sheep, whether antenatal glucocorticoid (betamethasone) exposure increased 8-isoprostane (marker of oxidative stress) and protein excretion after acute nephron reduction and intrarenal infusions of angiotensin peptides. We also examined whether renal proximal tubule cells (PTCs) could contribute to alterations in 8-isoprostane excretion in a sex-specific fashion. In vivo, ANG II significantly increased 8-isoprostane excretion by 49% and protein excretion by 44% in male betamethasone- but not in female betamethasone- or vehicle-treated sheep. ANG-(1-7) decreased 8-isoprostane excretion but did not affect protein excretion in either group. In vitro, ANG II stimulated 8-isoprostane release from PTCs of male but not female betamethasone-treated sheep. Male betamethasone-exposed sheep had increased p47 phox abundance in the renal cortex while superoxide dismutase (SOD) activity was increased only in females. We conclude that antenatal glucocorticoid exposure enhances the susceptibility of the kidney to oxidative stress induced by ANG II in a sex-specific fashion and the renal proximal tubule is one target of the sex-specific effects of antenatal steroids. ANG-(1-7) may mitigate the impact of prenatal glucocorticoids on the kidney. P47 phox activation may be responsible for the increased oxidative stress and proteinuria in males. The protection from renal oxidative stress in females is associated with increased SOD activity.

Metabolomics profile comparisons of irradiated and nonirradiated stored donor red blood cells

BACKGROUND

Understanding the metabolites that are altered by donor red blood cell (RBC) storage and irradiation may provide insight into the metabolic pathways disrupted by the RBC storage lesion.

STUDY DESIGN AND METHODS

Patterns of metabolites, representing more than 11,000 distinct mass-to-charge ratio (m/z) features, were compared between gamma-irradiated and nonirradiated CPDA-1-split RBCs from six human donors over 35 days of storage using multilevel sparse partial least squares discriminant analysis (msPLSDA), hierarchical clustering, pathway enrichment analysis, and network analysis.

RESULTS

In msPLSDA analysis, RBC units stored 7 days or fewer (irradiated or nonirradiated) showed similar metabolomic profiles. By contrast, donor RBCs stored 10 days or more demonstrated distinct clustering as a function of storage time and irradiation. Irradiation shifted metabolic features to those seen in older units. Hierarchical clustering analysis identified at least two clusters of metabolites that differentiated between RBC units based on storage time and irradiation exposure, confirming results of the msPLSDA analysis. Pathway enrichment analysis, used to map the discriminatory biochemical features to specific metabolic pathways, identified four pathways significantly affected by irradiation and/or storage including arachidonic acid (p = 3.3 × 10(-33)) and linoleic acid (p = 1.61 × 10(-11)) metabolism.

CONCLUSION

RBC storage under blood bank conditions produces numerous metabolic alterations. Gamma irradiation accentuates these differences as the age of blood increases, indicating that at the biochemical level irradiation accelerates metabolic aging of stored RBCs. Metabolites involved in the cellular membrane are prominently affected and may be useful biomarkers of the RBC storage lesion.

Oxidative stress early in infancy and neurodevelopmental outcome in very low-birthweight infants

BACKGROUND

Reactive oxygen species may be involved in serious diseases in premature infants. The objective of this study was to assess the relationship between neurodevelopmental outcome and oxidative stress marker level in the urine of very low-birthweight (VLBW) infants.

METHODS

Spot urine samples were collected from 35 VLBW infants. Urinary excretion of 8-hydroxy-2″-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, and 8-iso-prostaglandin F2α (8-isoPGF), a marker of lipid peroxidation, was measured at 1, 2, 4, and 6 weeks of age. Neurodevelopmental outcome at 18 months' corrected age was assessed using the Bayley Scales of Infant Development (BSID)-II.

RESULTS

Significant correlations were found between urinary 8-OHdG at 2 and 4 weeks and the Mental Development Index of the BSID-II. No significant correlation was found between urinary 8-isoPGF and indices of the BSID-II.

CONCLUSIONS

In VLBW infants, urinary 8-OHdG level correlated with mental development rather than psychomotor development at 18 months' corrected age; urinary 8-OHdG might be a predictive marker of neurodevelopmental outcome in VLBW infants.

ω-Alkynyl lipid surrogates for polyunsaturated fatty acids: free radical and enzymatic oxidations

Lipid and lipid metabolite profiling are important parameters in understanding the pathogenesis of many diseases. Alkynylated polyunsaturated fatty acids are potentially useful probes for tracking the fate of fatty acid metabolites. The nonenzymatic and enzymatic oxidations of ω-alkynyl linoleic acid and ω-alkynyl arachidonic acid were compared to that of linoleic and arachidonic acid. There was no detectable difference in the primary products of nonenzymatic oxidation, which comprised cis,trans-hydroxy fatty acids. Similar hydroxy fatty acid products were formed when ω-alkynyl linoleic acid and ω-alkynyl arachidonic acid were reacted with lipoxygenase enzymes that introduce oxygen at different positions in the carbon chains. The rates of oxidation of ω-alkynylated fatty acids were reduced compared to those of the natural fatty acids. Cyclooxygenase-1 and -2 did not oxidize alkynyl linoleic but efficiently oxidized alkynyl arachidonic acid. The products were identified as alkynyl 11-hydroxy-eicosatetraenoic acid, alkynyl 11-hydroxy-8,9-epoxy-eicosatrienoic acid, and alkynyl prostaglandins. This deviation from the metabolic profile of arachidonic acid may limit the utility of alkynyl arachidonic acid in the tracking of cyclooxygenase-based lipid oxidation. The formation of alkynyl 11-hydroxy-8,9-epoxy-eicosatrienoic acid compared to alkynyl prostaglandins suggests that the ω-alkyne group causes a conformational change in the fatty acid bound to the enzyme, which reduces the efficiency of cyclization of dioxalanyl intermediates to endoperoxide intermediates. Overall, ω-alkynyl linoleic acid and ω-alkynyl arachidonic acid appear to be metabolically competent surrogates for tracking the fate of polyunsaturated fatty acids when looking at models involving autoxidation and oxidation by lipoxygenases.

Oxidative balance score and oxidative stress biomarkers in a study of Whites, African Americans, and African immigrants

CONTEXT

Oxidative balance score (OBS) is a composite measure of multiple pro- and antioxidant exposures.

OBJECTIVE

To investigate associations of OBS with F2-isoprostanes (FIP), mitochondrial DNA copy number (mtDNA), and fluorescent oxidative products (FOP), and assess inter-relationships among the biomarkers.

METHODS

In a cross-sectional study, associations of a thirteen-component OBS with biomarker levels were assessed using multivariable regression models.

RESULTS

Association of OBS with FIP, but not with FOP, was in the hypothesized direction. The results for mtDNA were unstable and analysis-dependent. The three biomarkers were not inter-correlated.

CONCLUSIONS

Different biomarkers of oxidative stress may reflect different biological processes.

Lipid peroxidation: pathophysiological and pharmacological implications in the eye

Oxygen-derived free radicals such as hydroxyl and hydroperoxyl species have been shown to oxidize phospholipids and other membrane lipid components leading to lipid peroxidation. In the eye, lipid peroxidation has been reported to play an important role in degenerative ocular diseases (age-related macular degeneration, cataract, glaucoma, diabetic retinopathy). Indeed, ocular tissues are prone to damage from reactive oxygen species due to stress from constant exposure of the eye to sunlight, atmospheric oxygen and environmental chemicals. Furthermore, free radical catalyzed peroxidation of long chain polyunsaturated acids (LCPUFAs) such as arachidonic acid and docosahexaenoic acid leads to generation of LCPUFA metabolites including isoprostanes and neuroprostanes that may further exert pharmacological/toxicological actions in ocular tissues. Evidence from literature supports the presence of endogenous defense mechanisms against reactive oxygen species in the eye, thereby presenting new avenues for the prevention and treatment of ocular degeneration. Hydrogen peroxide (H2O2) and synthetic peroxides can exert pharmacological and toxicological effects on tissues of the anterior uvea of several mammalian species. There is evidence suggesting that the retina, especially retinal ganglion cells can exhibit unique characteristics of antioxidant defense mechanisms. In the posterior segment of the eye, H2O2 and synthetic peroxides produce an inhibitory action on glutamate release (using [(3)H]-D-aspartate as a marker), in vitro and on the endogenous glutamate and glycine concentrations in vivo. In addition to peroxides, isoprostanes can elicit both excitatory and inhibitory effects on norepinephrine (NE) release from sympathetic nerves in isolated mammalian iris ciliary bodies. Whereas isoprostanes attenuate dopamine release from mammalian neural retina, in vitro, these novel arachidonic acid metabolites exhibit a biphasic regulatory effect on glutamate release from retina and can regulate amino acid neurotransmitter metabolism without inducing cell death in the retina. Furthermore, there appears to be an inhibitory role for neuroprostanes in the release of excitatory amino acid neurotransmitters in mammalian retina. The ability of peroxides and metabolites of LCPUFA to alter the integrity of neurotransmitter pools provides new potential target sites and pathways for the treatment of degenerative ocular diseases.

Nutritional countermeasures targeting reactive oxygen species in cancer: from mechanisms to biomarkers and clinical evidence

Reactive oxygen species (ROS) exert various biological effects and contribute to signaling events during physiological and pathological processes. Enhanced levels of ROS are highly associated with different tumors, a Western lifestyle, and a nutritional regime. The supplementation of food with traditional antioxidants was shown to be protective against cancer in a number of studies both in vitro and in vivo. However, recent large-scale human trials in well-nourished populations did not confirm the beneficial role of antioxidants in cancer, whereas there is a well-established connection between longevity of several human populations and increased amount of antioxidants in their diets. Although our knowledge about ROS generators, ROS scavengers, and ROS signaling has improved, the knowledge about the direct link between nutrition, ROS levels, and cancer is limited. These limitations are partly due to lack of standardized reliable ROS measurement methods, easily usable biomarkers, knowledge of ROS action in cellular compartments, and individual genetic predispositions. The current review summarizes ROS formation due to nutrition with respect to macronutrients and antioxidant micronutrients in the context of cancer and discusses signaling mechanisms, used biomarkers, and its limitations along with large-scale human trials.

Treatment with an extract of Terminalia superba Engler & Diels decreases blood pressure and improves endothelial function in spontaneously hypertensive rats

ETHNOPHARMACOLOGICAL RELEVANCE

The stem bark of Terminalia superba (TS) is widely used as a decoction by Cameroonian folk medicine for the treatment of hypertension. The aim of the present study was to evaluate the effect of a chronic treatment with a TS extract on spontaneously hypertensive rats (SHR) with respect to efficacy, biochemical mechanisms and safety.

MATERIALS AND METHODS

Eleven-week-old SHR and normotensive Wistar Kyoto rats (WKY) were daily treated by gavage with a methylene chloride extract of stem bark of Terminalia superba (TMSE, 150mg/kg) or with the vehicle for 5 weeks. Systolic blood pressure (SBP) was measured weekly using the tail-cuff method. At the end of the treatment period, vascular function was assessed on isolated thoracic rings, urinary 8-iso-PGF2α levels were measured and cytochrome P-450 3A (CYP 3A) activity was evaluated in liver microsomes.

RESULTS

TMSE reduced SBP (P<0.001) in SHR but not in WKY rats. In SHR, the vasorelaxant response to acetylcholine was significantly improved by TMSE as a result of increased nitric oxide synthase (NO) activity and decreased superoxide anion production. In addition, TMSE reduced the vasoconstrictive effect of phenylephrine and improved the sensitivity of smooth muscle cells to NO. TMSE dramatically decreased 8-iso-PGF2α levels in SHR. By contrast, TMSE did not affect all these parameters in WKY rats. Neither diuresis nor the hepatic CYP 3A activity was modified in both animal groups.

CONCLUSIONS

This study demonstrated that Terminalia superba has a potent antihypertensive activity in SHR which is partly due to endothelium-dependent and endothelium-independent effects as well as decreased oxidative stress. The data also provide evidence for the lack of herb-drug interaction through hepatic CYP 3A.

New concepts in diabetic embryopathy

Diabetes mellitus is responsible for nearly 10% of fetal anomalies in diabetic pregnancies. Although aggressive perinatal care and glycemic control are available in developed countries, the birth defect rate in diabetic pregnancies remains higher than that in the general population. Major cellular activities (ie, proliferation and apoptosis) and intracellular metabolic conditions (ie, nitrosative, oxidative, and endoplasmic reticulum stress) have been shown to be associated with diabetic embryopathy using animal models. Translating advances made in animal studies into clinical applications in humans requires collaborative efforts across the basic research, preclinical, and clinical communities.

A prospective, randomized Phase II clinical trial to evaluate the effect of combined hyperbaric and normobaric hyperoxia on cerebral metabolism, intracranial pressure, oxygen toxicity, and clinical outcome in severe traumatic brain injury

OBJECT

Preclinical and clinical investigations indicate that the positive effect of hyperbaric oxygen (HBO2) for severe traumatic brain injury (TBI) occurs after rather than during treatment. The brain appears better able to use baseline O2 levels following HBO2 treatments. In this study, the authors evaluate the combination of HBO2 and normobaric hyperoxia (NBH) as a single treatment.

METHODS

Forty-two patients who sustained severe TBI (mean Glasgow Coma Scale [GCS] score 5.7) were prospectively randomized within 24 hours of injury to either: 1) combined HBO2/NBH (60 minutes of HBO2 at 1.5 atmospheres absolute [ATA] followed by NBH, 3 hours of 100% fraction of inspired oxygen [FiO2] at 1.0 ATA) or 2) control, standard care. Treatments occurred once every 24 hours for 3 consecutive days. Intracranial pressure, surrogate markers for cerebral metabolism, and O2 toxicity were monitored. Clinical outcome was assessed at 6 months using the sliding dichotomized Glasgow Outcome Scale (GOS) score. Mixed-effects linear modeling was used to statistically test differences between the treatment and control groups. Functional outcome and mortality rates were compared using chi-square tests.

RESULTS

There were no significant differences in demographic characteristics between the 2 groups. In comparison with values in the control group, brain tissue partial pressure of O2 (PO2) levels were significantly increased during and following combined HBO2/NBH treatments in both the noninjured and pericontusional brain (p < 0.0001). Microdialysate lactate/pyruvate ratios were significantly decreased in the noninjured brain in the combined HBO2/NBH group as compared with controls (p < 0.0078). The combined HBO2/NBH group's intracranial pressure values were significantly lower than those of the control group during treatment, and the improvement continued until the next treatment session (p < 0.0006). The combined HBO2/NBH group's levels of microdialysate glycerol were significantly lower than those of the control group in both noninjured and pericontusional brain (p < 0.001). The combined HBO2/NBH group's level of CSF F2-isoprostane was decreased at 6 hours after treatment as compared with that of controls, but the difference did not quite reach statistical significance (p = 0.0692). There was an absolute 26% reduction in mortality for the combined HBO2/NBH group (p = 0.048) and an absolute 36% improvement in favorable outcome using the sliding dichotomized GOS (p = 0.024) as compared with the control group.

CONCLUSIONS

In this Phase II clinical trial, in comparison with standard care (control treatment) combined HBO2/NBH treatments significantly improved markers of oxidative metabolism in relatively uninjured brain as well as pericontusional tissue, reduced intracranial hypertension, and demonstrated improvement in markers of cerebral toxicity. There was significant reduction in mortality and improved favorable outcome as measured by GOS. The combination of HBO2 and NBH therapy appears to have potential therapeutic efficacy as compared with the 2 treatments in isolation. CLINICAL TRIAL REGISTRATION NO.: NCT00170352 (ClinicalTrials.gov).

The effect of combining rosuvastatin with sartans of different peroxisome proliferator receptor-γ activating capacity on plasma 8-isoprostane prostaglandin F2a levels

INTRODUCTION

Oxidative stress is associated with the development and progression of cardiovascular disease. Plasma 8-isoprostane prostaglandin F2a (8-iso-PGF2a) levels are a reliable marker of oxidative stress.

MATERIAL AND METHODS

Patients (n = 151) with hypertension, dyslipidemia and impaired fasting glucose were randomly allocated to rosuvastatin (10 mg/day) plus telmisartan 80 mg/day (RT group, n = 52) or irbesartan 300 mg/day (RI group, n = 48) or olmesartan 20 mg/day (RO group, n = 51). After 6 months of treatment, changes in plasma 8-iso-PGF2a levels were blindly evaluated.

RESULTS

A decrease of 8-iso-PGF2a levels vs baseline was observed only in the RT group (-8.6%; p = 0.02). A trend for decrease vs. baseline was observed in the RI (-5.7%; p = 0.40) and RO (-3.7%; p = 0.60) groups. Changes of 8-iso-PGF2a levels between groups were not significantly different (p = 0.70).

CONCLUSIONS

The combination of rosuvastatin with sartans of different peroxisome proliferator receptor-γ activating capacity was associated with a decrease in levels of plasma 8-iso-PGF2a. This decrease reached significance only in the telmisartan group.

Can urinary excretion rate of 8-isoprostrane and malonaldehyde predict postoperative cognitive dysfunction in aging?

Oxidative stress has been associated with mild cognitive impairment (MCI) and Alzheimer's disease (AD). However, little is known about oxidative stress in postoperative cognitive dysfunction (POCD) in aging. The aim of this study was to investigate urinary excretion rate of 8-isoprostane:creatinine (U8-isoPG:Cr) and malonaldehyde:creatinine (UMDA:Cr) to predict short-term POCD in elderly patients undergoing general and orthopedic surgery. 72 patients aged above 65 years were enrolled in this prospective observational study. Each patient underwent cognitive testing to determine POCD performed by an investigator before surgery and 1 week after surgery. Morning urine was collected at baseline, 1, 2, and 7 days postoperatively. U8-isoPG was performed using enzymelinked immunosorbent assay (ELISA), and UMDA levels were measured by chemiluminescence detection. Creatinine levels were also analyzed if differences in the oxidative biomarkers were observed in the urine creatinine concentration. (1). Of 72 patients who completed cognitive testing, postoperative cognitive dysfunction was detected in 29.2 % (n = 21) of patients in 7 days. (2) U8-isoPG:Cr levels in 7 days postoperatively were significantly higher in POCD patients compared with the non-POCD group (p = 0.01). When measuring change from baseline, U8-isoPG:Cr levels were higher than that of control groups (p = 0.01). (3) UMDA:Cr levels were significantly elevated in 1 and 2 days postoperatively in both groups (p < 0.05). U8-isoPG:Cr level seems to be a valuable marker to detect lipid peroxidation early in POCD patients. However, it will also be important to take into account or reduce potential confounders to improve the identification of changes in the status of oxidative stress as a marker for POCD.

Eicosanoids and adipokines in breast cancer: from molecular mechanisms to clinical considerations

Chronic inflammation is one of the foremost risk factors for different types of malignancies, including breast cancer. Additional risk factors of this pathology in postmenopausal women are weight gain, obesity, estrogen secretion, and an imbalance in the production of adipokines, such as leptin and adiponectin. Various signaling products of transcription factor, nuclear factor-kappaB, in particular inflammatory eicosanoids, reactive oxygen species (ROS), and cytokines, are thought to be involved in chronic inflammation-induced cancer. Together, these key components have an influence on inflammatory reactions in malignant tissue damage when their levels are deregulated endogenously. Prostaglandins (PGs) are well recognized in inflammation and cancer, and they are solely biosynthesized through cyclooxygenases (COXs) from arachidonic acid. Concurrently, ROS give rise to bioactive isoprostanes from arachidonic acid precursors that are also involved in acute and chronic inflammation, but their specific characteristics in breast cancer are less demonstrated. Higher aromatase activity, a cytochrome P-450 enzyme, is intimately connected to tumor growth in the breast through estrogen synthesis, and is interrelated to COXs that catalyze the formation of both inflammatory and anti-inflammatory PGs such as PGE(2), PGF(2α), PGD(2), and PGJ(2) synchronously under the influence of specific mediators and downstream enzymes. Some of the latter compounds upsurge the intracellular cyclic adenosine monophosphate concentration and appear to be associated with estrogen synthesis. This review discusses the role of COX- and ROS-catalyzed eicosanoids and adipokines in breast cancer, and therefore ranges from their molecular mechanisms to clinical aspects to understand the impact of inflammation.

Lipid biomarkers of oxidative stress in a genetic mouse model of Smith-Lemli-Opitz syndrome

7-Dehydrocholesterol (7-DHC) accumulates in tissues and fluids of patients with Smith-Lemli-Opitz syndrome (SLOS), which is caused by mutations in the gene encoding 3β-hydroxysterol-Δ(7)-reductase (DHCR7). We recently reported that 7-DHC is the most reactive lipid molecule toward free radical oxidation (lipid peroxidation) and 14 oxysterols have been identified as products of oxidation of 7-DHC in solution. As the high oxidizability of 7-DHC may lead to systemic oxidative stress in SLOS patients, we report here lipid biomarkers of oxidative stress in a Dhcr7-KO mouse model of SLOS, including oxysterols, isoprostanes (IsoPs), and neuroprostanes (NeuroPs) that are formed from the oxidation of 7-DHC, arachidonic acid and docosahexaenoic acid, respectively. In addition to a previously described oxysterol, 3β,5α-dihydroxycholest-7-en-6-one (DHCEO), we provide evidence for the chemical structures of three new oxysterols in the brain and/or liver tissue of Dhcr7-KO mice, two of which were quantified. We find that levels of IsoPs and NeuroPs are also elevated in brain and/or liver tissues of Dhcr7-KO mice relative to matching WT mice. While IsoPs and NeuroPs have been established as a reliable measurement of lipid peroxidation and oxidative stress in vivo, we show that in this genetic SLOS mouse model, 7-DHC-derived oxysterols are present at much higher levels than IsoPs and NeuroPs and thus are better markers of lipid oxidation and related oxidative stress.

Acute and chronic fluctuations in blood glucose levels can increase oxidative stress in type 2 diabetes mellitus

In order to investigate whether short- or long-term glycemic fluctuations could induce oxidative stress and chronic inflammation, we evaluated the relationships between glycemic variability, oxidative stress markers, and high-sensitivity C-reactive protein (hs-CRP). We enrolled 34 patients with type 2 diabetes. As a measure of short-term glycemic variability, mean amplitude of glycemic excursions (MAGE) was computed from continuous glucose monitoring system data. For determining long-term glycemic variability, we calculated the standard deviation (SD) of hemoglobin A1c (HbA1c) levels measured over a 2-year period. Levels of oxidative stress markers: 8-iso-prostaglandin F2α (8-iso-PGF2α), thiobarbituric acid-reactive substance (TBARS), 8-hydroxydeoxyguanosine (8-OHdG), and hs-CRP were measured. MAGE was significantly correlated with the SD of HbA1c levels (r = 0.73, p < 0.001) but not with HbA1c level. The levels of hs-CRP, TBARS, 8-OHdG, and 8-iso-PGF2α were significantly correlated with MAGE (r = 0.54, p = 0.001; r = 0.82, p < 0.001; r = 0.70, p < 0.001; r = 0.60, p < 0.001) and the SD of HbA1c levels (r = 0.53, p = 0.001; r = 0.73, p < 0.001; r = 0.69, p < 0.001; r = 0.43, p = 0.01) but not with HbA1c level. Relationships between 8-iso-PGF2α and MAGE or the SD of HbA1c levels remained significant after adjusting for other markers of diabetic control (R(2) = 0.684, R(2) = 0.595, p < 0.001, respectively). Both acute and chronic blood glucose variability can induce oxidative stress and chronic inflammation.

Fruit and vegetable intake and the association with glucose parameters: a cross-sectional analysis of the Let's Prevent Diabetes Study

BACKGROUND

Dietary recommendations for the prevention of type 2 diabetes mellitus include the message to consume 400 g fruit and vegetables per day. Measurement of habitual diet is inherently difficult, yet errors due to self-report can be eliminated by the use of nutritional biomarkers. The aim of this study was to determine plasma vitamin C concentrations as a biomarker for fruit and vegetable intake in individuals identified at high risk of diabetes. Fruit and vegetables may confer benefit via their antioxidant capacity, thus we also measured urinary F₂-isoprostanes as a marker for oxidative stress.

SUBJECTS/METHODS

Participants recruited from a high-risk population as part of a diabetes prevention trial provided fasting blood samples and a spot urine sample for the quantification of plasma vitamin C and F₂-isoprostanes, respectively. We compared glycaemic parameters by the increments of the standard deviation of plasma vitamin C using multiple regression models.

RESULTS

Mean plasma vitamin C of participants was 39.3 μmol/l (s.d. 21.8). In the unadjusted model, 1 s.d. plasma vitamin C was significantly and inversely associated with HbA1c, fasting and 2 h blood glucose (P ≤ 0.0001). Relationships remained significant after adjustment for demographic variables and confounding factors. No significant association was observed between plasma vitamin C and urinary F₂-isoprostanes.

CONCLUSION

The data adds to the evidence that small lifestyle changes may influence glucose regulation. The role that fruit and vegetables independently have should be investigated further.

Urinary F2-isoprostanes, obesity, and weight gain in the IRAS cohort

Obesity has been associated with increased F(2)-isoprostane (F(2)-IsoP) levels cross-sectionally. However, the prospective association may be inverse, based on our earlier finding that elevated urinary F(2)-IsoP levels predict lower risk of diabetes. This earlier finding led us to hypothesize that urinary F(2)-IsoPs reflect the intensity of oxidative metabolism and as such predict lower risk of both diabetes and weight gain. We examined cross-sectional relationships with obesity and prospective relationships with weight gain using the data from 299 participants of the Insulin Resistance Atherosclerosis Study (IRAS), all of whom were free of diabetes at baseline. Four urinary F(2)-IsoPs were assayed in stored baseline urine samples using liquid chromatography with tandem mass spectrometry: iPF(2α)-III, 2,3-dinor-iPF(2α)-III, iPF(2α)-VI, and 8,12-iso-iPF(2α)-VI (F(2)-IsoP 1-4, respectively). Baseline F(2)-IsoPs were positively associated with baseline measures of obesity; the strongest associations were found with two F(2)-IsoPs: odds ratios (95% confidence intervals) for overall and abdominal obesity were 1.74 (1.26-2.40) and 1.63 (1.18-2.24) for F(2)-IsoP2 and 1.47 (1.12-1.94) and 1.64 (1.22-2.20) for F(2)-IsoP4. F(2)-IsoP2 showed the strongest and significant inverse association with weight gain during the 5-year follow-up period: increase in F(2)-IsoP2 equal to 1 s.d. was associated with 0.90 kg lower weight gain (P = 0.02) and the odds ratios for relative (≥5%) and absolute (≥5 kg) weight gain were 0.67 (0.47-0.96) and 0.57 (0.37-0.87), respectively. The other three F(2)-IsoPs were consistently inversely associated with weight gain, although not significantly, suggesting that different F(2)-IsoPs vary in their ability to detect the association with weight gain.

Cord blood 8-isoprostane in the preterm infant

BACKGROUND

Cord blood 8-isoprostane (8-IP) is a marker of lipid peroxidation in the peripartum period. The independent association with degree of prematurity is not well-described.

OBJECTIVE

To identify patterns of lipid peroxidation among early, moderate and late preterm infants, and to understand how cord blood 8-IP varies with gestational age (GA) and related covariates.

STUDY DESIGN

Mother-infant pairs from 237 preterm births were studied as part of a longitudinal birth cohort study. GA subgroups were defined as extremely (≤28w), moderately (29-33w), and late (34-36w) preterm. Cord blood 8-IP was measured using EIA. Elevated 8-IP (4th quartile) was the primary outcome for multivariate logistic regression models, which were adjusted for maternal age/race, multiple gestation and infant gender, as well as other relevant covariates.

RESULTS

Elevated 8-IP was associated with extremely preterm birth (OR=4.31; 95% CI=1.90, 9.76), and was inversely associated with increasing GA (OR=0.88; 95% CI=0.80, 0.97). Elevated 8-IP was also associated with decreasing birth weight (BW), clinical chorioamnionitis, fetal inflammatory response of the placenta (FIR), and signs of perinatal depression. The GA on 8-IP association appeared to be modified by several maternal disease and fetal-infant factors. Lastly, the indirect associations between log-transformed 8-IP, GA and BW appeared to be most prominent for GA<30w and for BW<2000g.

CONCLUSION

Lipid peroxidation in preterm birth, and the relative influence of accompanying peripartum factors, varies according to degree of prematurity. These findings have important implications for the developmental regulation of antioxidant defense and its impact on neonatal outcomes.

Urinary biomarkers of oxidative status

Oxidative damage produced by reactive oxygen species (ROS) has been implicated in the etiology and pathology of many health conditions, including a large number of chronic diseases. Urinary biomarkers of oxidative status present a great opportunity to study redox balance in human populations. With urinary biomarkers, specimen collection is non-invasive and the organic/metal content is low, which minimizes the artifactual formation of oxidative damage to molecules in specimens. Also, urinary levels of the biomarkers present intergraded indices of redox balance over a longer period of time compared to blood levels. This review summarizes the criteria for evaluation of biomarkers applicable to epidemiological studies and evaluation of several classes of biomarkers that are formed non-enzymatically: oxidative damage to lipids, proteins, DNA, and allantoin, an oxidative product of uric acid. The review considers formation, metabolism, and exertion of each biomarker, available data on validation in animal and clinical models of oxidative stress, analytical approaches, and their intra- and inter-individual variation. The recommended biomarkers for monitoring oxidative status over time are F₂-isoprostanes and 8-oxodG. For inter-individual comparisons, F₂-isoprostanes are recommended, whereas urinary 8-oxodG levels may be confounded by differences in the DNA repair capacity. Promising urinary biomarkers include allantoin, acrolein-lysine, and dityrosine.

Diabetes and cancer II: role of diabetes medications and influence of shared risk factors

An association between type 2 diabetes mellitus (DM) and cancer has long been postulated, but the biological mechanism responsible for this association has not been defined. In part one of this review, we discussed the epidemiological evidence for increased risk of cancer, decreased cancer survival, and decreased rates of cancer screening in diabetic patients. Here we review the risk factors shared by cancer and DM and how DM medications play a role in altering cancer risk. Hyperinsulinemia stands out as a major factor contributing to the association between DM and cancer, and modulation of circulating insulin levels by DM medications appears to play an important role in altering cancer risk. Drugs that increase circulating insulin, including exogenous insulin, insulin analogs, and insulin secretagogues, are generally associated with an increased cancer risk. In contrast, drugs that regulate insulin signaling without increasing levels, especially metformin, appear to be associated with a decreased cancer risk. In addition to hyperinsulinemia, the effect of DM medications on other shared risk factors including hyperglycemia, obesity, and oxidative stress as well as demographic factors that may influence the use of certain DM drugs in different populations are described. Further elucidation of the mechanisms behind the association between DM, cancer, and the role of DM medications in modulating cancer risk may aid in the development of better prevention and treatment options for both DM and cancer. Additionally, incorporation of DM medication use into cancer prediction models may lead to the development of improved risk assessment tools for diabetic patients.