Mass spectrometric quantification of F2-isoprostanes in biological fluids and tissues as measure of oxidant stress

Mass Spectrometry-Based Evaluation of the Bland-Altman Approach: Review, Discussion, and Proposal

Reliable quantification in biological systems of endogenous low- and high-molecular substances, drugs and their metabolites, is of particular importance in diagnosis and therapy, and in basic and clinical research. The analytical characteristics of analytical approaches have many differences, including in core features such as accuracy, precision, specificity, and limits of detection (LOD) and quantitation (LOQ). Several different mathematic approaches were developed and used for the comparison of two analytical methods applied to the same chemical compound in the same biological sample. Generally, comparisons of results obtained by two analytical methods yields different quantitative results. Yet, which mathematical approach gives the most reliable results? Which mathematical approach is best suited to demonstrate agreement between the methods, or the superiority of an analytical method A over analytical method B? The simplest and most frequently used method of comparison is the linear regression analysis of data observed by method A (y) and the data observed by method B (x): y = α + βx. In 1986, Bland and Altman indicated that linear regression analysis, notably the use of the correlation coefficient, is inappropriate for method-comparison. Instead, Bland and Altman have suggested an alternative approach, which is generally known as the Bland-Altman approach. Originally, this method of comparison was applied in medicine, for instance, to measure blood pressure by two devices. The Bland-Altman approach was rapidly adapted in analytical chemistry and in clinical chemistry. To date, the approach suggested by Bland-Altman approach is one of the most widely used mathematical approaches for method-comparison. With about 37,000 citations, the original paper published in the journal The Lancet in 1986 is among the most frequently cited scientific papers in this area to date. Nevertheless, the Bland-Altman approach has not been really set on a quantitative basis. No criteria have been proposed thus far, in which the Bland-Altman approach can form the basis on which analytical agreement or the better analytical method can be demonstrated. In this article, the Bland-Altman approach is re-valuated from a quantitative bioanalytical perspective, and an attempt is made to propose acceptance criteria. For this purpose, different analytical methods were compared with Gold Standard analytical methods based on mass spectrometry (MS) and tandem mass spectrometry (MS/MS), i.e., GC-MS, GC-MS/MS, LC-MS and LC-MS/MS. Other chromatographic and non-chromatographic methods were also considered. The results for several different endogenous substances, including nitrate, anandamide, homoarginine, creatinine and malondialdehyde in human plasma, serum and urine are discussed. In addition to the Bland-Altman approach, linear regression analysis and the Oldham-Eksborg method-comparison approaches were used and compared. Special emphasis was given to the relation of difference and mean in the Bland-Altman approach. Currently available guidelines for method validation were also considered. Acceptance criteria for method agreement were proposed, including the slope and correlation coefficient in linear regression, and the coefficient of variation for the percentage difference in the Bland-Altman and Oldham-Eksborg approaches.

Green tea extract supplementation does not modify plasma concentration of F2-isoprostanes in women who are postmenopause: Findings from a randomized controlled trial

Green tea extract (GTE) is a potential mitigator of oxidative stress, and F2-isoprostanes are a reliable biomarker of oxidative stress. Genetic polymorphisms in the catechol-o-methyltransferase (COMT) gene may modify tea catechin metabolism, prolonging exposure. We hypothesized that GTE supplementation would decrease plasma F2-isoprostanes concentrations compared with placebo and that participants with the COMT genotype polymorphisms would experience a more significant expression of this outcome. This study was a secondary analysis of the Minnesota Green Tea Trial, a randomized placebo-controlled, double-blinded trial investigating the effects of GTE in women who were generally healthy and postmenopausal. The treatment group consumed 843 mg of epigallocatechin gallate daily for 12 months versus placebo. Participants in this study had a mean age of 60 years, were predominantly White, and most had a healthy body mass index. GTE supplementation did not significantly change plasma F2-isoprostanes concentrations compared with placebo after 12 months (P for overall treatment = .07). There were no significant interactions between treatment and age, or body mass index, physical activity, smoking history, and alcohol intake. COMT genotype did not modify the effect of GTE supplementation on F2-isoprostanes concentrations in the treatment group (P = .85). Among participants in the Minnesota Green Tea Trial, consuming GTE supplements daily for 1 year did not result in a significant decrease in plasma F2-isoprostanes concentrations. Likewise, the COMT genotype did not modify the effect of GTE supplementation on F2-isoprostanes concentrations.

Quantification of Plasma 8-Isoprostane by High-Performance Liquid Chromatography with Tandem Mass Spectrometry in a Case-Control Study of Lung Cancer

AIM

8-iso-prostaglandin F2α is a biomarker of lipid peroxidation, and one of the most commonly used measures of oxidative stress. It is an established biomarker of lung cancer risk. It is commonly measured by enzyme-linked immunosorbent assay. Given its importance, we developed a stable isotope dilution UPLC-tandem mass spectrometric method for the rapid determination of 8-isoprostane in blood.

METHODS

We tested the discriminatory capability of the method in 49 lung cancer patients, 55 benign lung nodule patients detected by chest X-ray, and 41 patients with chronic obstructive pulmonary disease (COPD) or asthma.

RESULTS

Significant differences were found in mean 8-isoprostane levels between the three groups (p = 0.027), and post-hoc tests found higher levels in the lung cancer patients than in patients with benign nodules (p = 0.032) and COPD/asthma (p = 0.014). The receiving operating characteristic area under the curve (AUC) was 0.69 for differentiating the lung cancer group from the benign nodule group, and 0.7 for differentiating from the COPD/asthma group.

CONCLUSIONS

The UPLC-MS/MS-based method is an efficient analytical tool for measuring 8-isoprostane plasma concentrations. The results suggest exploring its utility as a marker for early lung cancer screening.

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.

Oklahoma Nathan Shock Aging Center - assessing the basic biology of aging from genetics to protein and function

The Oklahoma Shock Nathan Shock Center is designed to deliver unique, innovative services that are not currently available at most institutions. The focus of the Center is on geroscience and the development of careers of young investigators. Pilot grants are provided through the Research Development Core to junior investigators studying aging/geroscience throughout the USA. However, the services of our Center are available to the entire research community studying aging and geroscience. The Oklahoma Nathan Shock Center provides researchers with unique services through four research cores. The Multiplexing Protein Analysis Core uses the latest mass spectrometry technology to simultaneously measure the levels, synthesis, and turnover of hundreds of proteins associated with pathways of importance to aging, e.g., metabolism, antioxidant defense system, proteostasis, and mitochondria function. The Genomic Sciences Core uses novel next-generation sequencing that allows investigators to study the effect of age, or anti-aging manipulations, on DNA methylation, mitochondrial genome heteroplasmy, and the transcriptome of single cells. The Geroscience Redox Biology Core provides investigators with a comprehensive state-of-the-art assessment of the oxidative stress status of a cell, e.g., measures of oxidative damage and redox couples, which are important in aging as well as many major age-related diseases as well as assays of mitochondrial function. The GeroInformatics Core provides investigators assistance with data analysis, which includes both statistical support as well as analysis of large datasets. The Core also has developed number of unique software packages to help with interpretation of results and discovery of new leads relevant to aging. In addition, the Geropathology Research Resource in the Program Enhancement Core provides investigators with pathological assessments of mice using the recently developed Geropathology Grading Platform.

Glycomacropeptide for Management of Insulin Resistance and Liver Metabolic Perturbations

BACKGROUND AND AIMS

The increasing prevalence and absence of effective global treatment for metabolic syndrome (MetS) are alarming given the potential progression to severe non-communicable disorders such as type 2 diabetes and nonalcoholic fatty liver disease. The purpose of this study was to investigate the regulatory role of glycomacropeptide (GMP), a powerful milk peptide, in insulin resistance and liver dysmetabolism, two central MetS conditions.

MATERIALS AND METHODS

C57BL/6 male mice were fed a chow (Ctrl), high-fat, high-sucrose (HFHS) diet or HFHS diet along with GMP (200 mg/kg/day) administered by gavage for 12 weeks.

RESULTS

GMP lowered plasma insulin levels (in response to oral glucose tolerance test) and HOMA-IR index, indicating a more elevated systemic insulin sensitivity. GMP was also able to decrease oxidative stress and inflammation in the circulation as reflected by the decline of malondialdehyde, F2 isoprostanes and lipopolysaccharide. In the liver, GMP raised the protein expression of the endogenous anti-oxidative enzyme GPx involving the NRF2 signaling pathway. Moreover, the administration of GMP reduced the gene expression of hepatic pro-inflammatory COX-2, TNF-α and IL-6 via inactivation of the TLR4/NF-κB signaling pathway. Finally, GMP improved hepatic insulin sensitization given the modulation of AKT, p38 MAPK and SAPK/JNK activities, thereby restoring liver homeostasis as revealed by enhanced fatty acid β-oxidation, reduced lipogenesis and gluconeogenesis.

CONCLUSIONS

Our study provides evidence that GMP represents a promising dietary nutraceutical in view of its beneficial regulation of systemic insulin resistance and hepatic insulin signaling pathway, likely via its powerful antioxidant and anti-inflammatory properties.

A Brief Overview of Oxidative Stress in Adipose Tissue with a Therapeutic Approach to Taking Antioxidant Supplements

One of the leading causes of obesity associated with oxidative stress (OS) is excessive consumption of nutrients, especially fast-foods, and a sedentary lifestyle, characterized by the ample accumulation of lipid in adipose tissue (AT). When the body needs energy, the lipid is broken down into glycerol (G) and free fatty acids (FFA) during the lipolysis process and transferred to various tissues in the body. Materials secreted from AT, especially adipocytokines (interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α)) and reactive oxygen species (ROS), are impressive in causing inflammation and OS of AT. There are several ways to improve obesity, but researchers have highly regarded the use of antioxidant supplements due to their neutralizing properties in removing ROS. In this review, we have examined the AT response to OS to antioxidant supplements focusing on animal studies. The results are inconsistent due to differences in the study duration and diversity in animals (strain, age, and sex). Therefore, there is a need for different studies, especially in humans.

Maternal Urinary Metal and Metalloid Concentrations in Association with Oxidative Stress Biomarkers

Metal exposure has been associated with a wide range of adverse birth outcomes and oxidative stress is a leading hypothesis of the mechanism of action of metal toxicity. We assessed the relationship between maternal exposure to essential and non-essential metals and metalloids in pregnancy and oxidative stress markers, and sought to identify windows of vulnerability and effect modification by fetal sex. In our analysis of 215 women from the PROTECT birth cohort study, we measured 14 essential and non-essential metals in urine samples at three time points during pregnancy. The oxidative stress marker 8-iso-prostaglandin F2α (8-iso-PGF2α) and its metabolite 2,3-dinor-5,6-dihydro-15-15-F2t-IsoP, as well as prostaglandin F2α (PGF2α), were also measured in the same urine samples. Using linear mixed models, we examined the main effects of metals on markers of oxidative stress as well as the visit-specific and fetal sex-specific effects. After adjustment for covariates, we found that a few urinary metal concentrations, most notably cesium (Cs) and copper (Cu), were associated with higher 8-iso-PGF2α with effect estimates ranging from 7.3 to 14.9% for each interquartile range, increase in the metal concentration. The effect estimates were generally in the same direction at the three visits and a few were significant only among women carrying a male fetus. Our data show that higher urinary metal concentrations were associated with elevated biomarkers of oxidative stress. Our results also indicate a potential vulnerability of women carrying a male fetus.

Differences in erythrocyte phospholipid membrane long-chain polyunsaturated fatty acids and the prevalence of fatty acid desaturase genotype among African Americans and European Americans

Numerous studies have reported an association between genetic variants in fatty acid desaturases (FADS1 and FADS2) and plasma or erythrocyte long chain polyunsaturated fatty acid (PUFA) levels. Increased levels of n-6 PUFAs have been associated with inflammation and several chronic diseases, including diabetes and cancer. We hypothesized that genetic variants of FADS that more efficiently convert precursor n-6 PUFA to arachidonic acid (AA) may explain the higher burden of chronic diseases observed in African Americans. To test this hypothesis, we measured the level of n-6 and n-3 PUFAs in erythrocyte membrane phospholipids and genotyped the rs174537 FADS variants associated with higher AA conversion among African American and European American populations. We included data from 1,733 individuals who participated in the Tennessee Colorectal Polyp Study, a large colonoscopy-based case-control study. Erythrocyte membrane PUFA percentages were measured using gas chromatography. Generalized linear models were used to estimate association of race and genotype on erythrocyte phospholipid membrane PUFA levels while controlling for self-reported dietary intake. We found that African Americans have higher levels of AA and a higher prevalence of GG allele compared to whites, 81% vs 43%, respectively. Homozygous GG genotype was negatively associated with precursor PUFAs (linoleic [LA], di-homo-γ-linolenic [DGLA]), positively associated with both product PUFA (AA, docosahexaenoic acid [DHA]), product to precursor ratio (AA to DGLA), an indirect measure of FADs efficiency and increased urinary isoprostane F2 (F2-IsoP) and isoprostane F3 (F3-IsoP), markers of oxidative stress. Increased consumption of n-6 PUFA and LA resulting in increased AA and subsequent inflammation may be fueling increased prevalence of chronic diseases especially in African descent.

The Associations of Perceived and Oxidative Stress with Hypertension in a Cohort of Police Officers

PURPOSE

Associations between perceived stress and oxidative stress marker and metabolic syndrome (MetS) components were investigated in a cohort of police officers.

METHODS

Cross-sectional data from a cohort of non-diabetic subjects (n=233; 19F), median [interquartile range] age 50 [37-44] years, were analysed. MetS was construed in line with International Diabetes Federation (IDF) criteria and perceived stress with Cohen's 10-item Perceived Stress Scale. Plasma oxidative stress marker (free 8-iso-prostaglandin F_2α; 8-iso-PGF_2α), presence of coronary plaque, carotid artery intima-media thickness (cIMT), and physical activity level were also determined.

RESULTS

Obesity was established in 100 (42.92%), hypertension in 111 (47.64), whereas MetS was identified in 104 (44.63%) of the study subjects. A significant difference (p=0.003) in plasma 8-iso-PGF_2α level, depending on the MetS components status, was noted. The associations of perceived stress with plasma 8-iso-PGF_2α level and the select study variables were gender-specific. In multivariate analysis (adjusted for age and current smoking), positive associations of plasma 8-iso-PGF_2α levels with PSS score (B=0.108, 95% CI [0.008, 0.209], p=0.03) and systolic blood pressure (B=0.029, 95% CI [0.003, 0.057], p=0.02) in men only were established. Both the perceived stress (OR 1.101, 95% CI [1.001-1.202], p=0.03) and plasma 8-iso-PGF_2α levels (OR 1.223, 95% CI [1.046-1.432], p=0.01) impacted the prevalence of hypertension. Out of the MetS components, the effect of waist circumference (OR=1.138, 95% CI [1.064-1.218], p=0.0001) and glucose (B=2.696, 95% CI [1.081-6.725], p=0.03) were also encountered. No such associations were noted in women, though, neither in univariate nor in multivariate analyses. The prevalence of coronary plaque (0.001), obesity (p<0.001), hypertension (p<0.001) and median cIMT value (p=0.005), as well as leisure-time (p=0.04) and total walking physical activity (p=0.03), differed significantly between the subgroups stratified by MetS components status.

CONCLUSION

Both the perceived and oxidative stress were found instrumental in promoting hypertension in a cohort of police officers under study, whereas all study outcomes were conclusively gender-related.

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.

Methods of the Analysis of Oxylipins in Biological Samples

Oxylipins are derivatives of polyunsaturated fatty acids and due to their important and diverse functions in the body, they have become a popular subject of studies. The main challenge for researchers is their low stability and often very low concentration in samples. Therefore, in recent years there have been developments in the extraction and analysis methods of oxylipins. New approaches in extraction methods were described in our previous review. In turn, the old analysis methods have been replaced by new approaches based on mass spectrometry (MS) coupled with liquid chromatography (LC) and gas chromatography (GC), and the best of these methods allow hundreds of oxylipins to be quantitatively identified. This review presents comparative and comprehensive information on the progress of various methods used by various authors to achieve the best results in the analysis of oxylipins in biological samples.

Potential roles of psychological and oxidative stress in insulin resistance: a cohort-based study

BACKGROUND

The present study investigated the relationships between psychological stress indices and oxidative stress marker, also when combined with emergent insulin resistance (IR), in the non-diabetic, middle-aged subjects, exposed to frequent/chronic psychological stressors.

METHODS

Cross-sectional data from a cohort of non-diabetic police officers (n = 234; 19F), aged 27-56 years, were used. Plasma inflammatory (CRP, TNF-α), oxidative stress (free 8-iso-prostaglandin F_2α; 8-iso-PGF_2α) markers, and insulin were measured. The value of homeostasis model assessment of IR index (HOMA-IR) was assumed the threshold value of IR, i.e. 2.04. Free cortisol in urine and perceived stress (psychological stress indices) were also measured.

RESULTS

In the IR subjects, most biochemical variables, inflammatory markers and urine cortisol were significantly higher, as compared to the non-IR ones. Psychological stress indices were associated with plasma 8-iso-PGF_2α [B = 0.139, 95% CI (0.048, 0.230), p = 0.002, and B = 0.007, 95% CI (0.0006, 0.014), p = 0.03; for perceived stress level and cortisol, respectively]. Positive associations were established between plasma 8-iso-PGF_2α [B = 0.069, 95% CI (0.016-0.120), p = 0.01] and urine cortisol [B = 0.003, 95% CI (0.0003, 0.005), p = 0.02] with HOMA-IR. Metabolic syndrome, as defined by IDF criteria, was established in 110 study subjects, whereas 136 of them were hypertensive. Waist circumference [B = 0.056, 95% CI (0.039, 0.074), p < 0.0001], and systolic blood pressure [B = 0.009, 95% CI (0.00003, 0.018), p = 0.04] were positively associated with HOMA-IR, whereas the association of HDL cholesterol [B = - 0.597, 95% CI (- 1.139, - 0.055), p = 0.03] was a negative one. Cortisol [OR = 1.007, 95% CI (1.002, 1.012), p = 0.006], and 8-iso-PGF_2α [OR = 1.103, 95% CI (1.010, 1.201), p = 0.02] affected the incidence of IR. After adjustment for metabolic syndrome (or its components), age, sex, and current smoking, the effects became non-significant. Out of metabolic syndrome components, waist circumference [OR 4.966, 95% CI (2.29, 10.751), p = 0.00004] and hypertriglyceridemia [OR 1.993, 95% CI (1.063, 3.736), p = 0.03] increased the chance of IR incidence.

CONCLUSIONS

Both psychological stress indices were associated with oxidative stress, but only cortisol with HOMA-IR. In the subjects exposed to frequent/chronic psychological stressors, cortisol and oxidative stress marker affected IR incidence, being statistically attenuated, though, following adjustment for metabolic syndrome, or its components.

Mice Lacking the Cytochrome P450 1B1 Gene Are Less Susceptible to Hyperoxic Lung Injury Than Wild Type

Supplemental oxygen is a life-saving intervention administered to individuals suffering from respiratory distress, including adults with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Despite the clinical benefit, supplemental oxygen can create a hyperoxic environment that increases reactive oxygen species, oxidative stress, and lung injury. We have previously shown that cytochrome P450 (CYP)1A enzymes decrease susceptibility to hyperoxia-induced lung injury. In this investigation, we determined the role of CYP1B1 in hyperoxic lung injury in vivo. Eight- to ten-week old C57BL/6 wild type (WT) and Cyp1b1-/- mice were exposed to hyperoxia (>95% O2) for 24-72 h or maintained in room air (21% O2). Lung injury was assessed by histology and lung weight to body weight (LW/BW) ratios. Extent of inflammation was determined by assessing pulmonary neutrophil infiltration and cytokine levels. Lipid peroxidation markers were quantified by gas chromatography mass spectrometry, and oxidative DNA adducts were quantified by 32P-postlabeling as markers of oxidative stress. We found that Cyp1b1-/- mice displayed attenuation of lung weight and pulmonary edema, particularly after 48-72 h of hyperoxia compared with WT controls. Further, Cyp1b1-/- mice displayed decreased levels of pulmonary oxidative DNA adducts and pulmonary isofurans after 24 h of hyperoxia. Cyp1b1-/- mice also showed increased pulmonary CYP1A1 and 1A2 and mRNA expression. In summary, our results support the hypothesis that Cyp1b1-/- mice display decreased hyperoxic lung injury than wild type counterparts and that CYP1B1 may act as a pro-oxidant during hyperoxia exposure, contributing to increases in oxidative DNA damage and accumulation of lipid hydroperoxides.

Tea consumption and oxidative stress: a cross-sectional analysis of 889 premenopausal women from the Sister Study

In experimental and clinical studies, green or black tea consumption has been shown to reduce oxidative stress. However, these studies involved high levels of tea consumption and may not reflect patterns in the general population. Here, we examined the association between black or green tea consumption and oxidative stress in a cross-sectional study of 889 premenopausal US women aged 35-54 years. Tea consumption was measured using the Block-98 FFQ. Urinary 8-iso-PGF2α (F2-IsoP) and 2,3-dinor-5,6-dihydro-15-F2t-isoprostane (15-F2t-IsoP-M) were used as biomarkers of oxidative stress. These compounds were measured by MS and normalised to creatinine. Linear regression was used to calculate the geometric mean differences (GMD) and 95% CI for log-transformed urinary F2-IsoP or 15-F2t-IsoP-M in relation to black or green tea consumption. We further examined whether adjusting for caffeine impacted associations between tea and oxidative stress. Geometric means of urinary F2-IsoP and 15-F2t-IsoP-M were 1·44 (95% CI 1·39, 1·49) and 0·71 (95% CI 0·69, 0·73) ng/mg creatinine, respectively. Overall, green tea consumption was not associated with urinary F2-IsoP or 15-F2t-IsoP-M. High-level black tea consumption (≥5 cups/week compared with 0) was associated with higher 15-F2t-IsoP-M concentrations (adjusted GMD=0·10, 95 % CI 0·02-0.19) but not F2-IsoP. Adjusting for caffeine nullified the association between black tea and 15-F2t-IsoP-M. Our findings do not support the hypothesis that dietary tea consumption is inversely associated with oxidative stress.

Deuterated polyunsaturated fatty acids reduce brain lipid peroxidation and hippocampal amyloid β-peptide levels, without discernable behavioral effects in an APP/PS1 mutant transgenic mouse model of Alzheimer's disease

Alzheimer's disease (AD) involves progressive deposition of amyloid β-peptide (Aβ), synapse loss, and neuronal death, which occur in brain regions critical for learning and memory. Considerable evidence suggests that lipid peroxidation contributes to synaptic dysfunction and neuronal degeneration, both upstream and downstream of Aβ pathology. Recent findings suggest that lipid peroxidation can be inhibited by replacement of polyunsaturated fatty acids (PUFA) with isotope-reinforced (deuterated) PUFA (D-PUFA), and that D-PUFA can protect neurons in experimental models of Parkinson's disease. Here, we determined whether dietary D-PUFA would ameliorate Aβ pathology and/or cognitive deficits in a mouse model of AD (amyloid precursor protein/presenilin 1 double mutant transgenic mice). The D-PUFA diet did not ameliorate spatial learning and memory deficits in the AD mice. Compared to mice fed an hydrogenated-PUFA control diet, those fed D-PUFA for 5 months exhibited high levels of incorporation of deuterium into arachidonic acid and docosahexaenoic acid, and reduced concentrations of lipid peroxidation products (F2 isoprostanes and neuroprostanes), in the brain tissues. Concentrations of Aβ40 and Aβ38 in the hippocampus were significantly lower, with a trend to reduced concentrations of Aβ42, in mice fed D-PUFA compared to those fed hydrogenated-PUFA. We conclude that a D-PUFA diet reduces the brain tissue concentrations of both arachidonic acid and docosahexaenoic acid oxidation products, as well as the concentration of Aβs.

Associations of mitochondrial polymorphisms with sporadic colorectal adenoma

Somatic mutations in mitochondrial DNA have been reported in colorectal adenomatous polyps (adenomas), the precursors to most colorectal cancers. However, there are no reports of associations of germline variation in mitochondrial DNA with adenoma risk. We investigated associations of germline polymorphisms in the displacement loop (D-loop) and non-D-loop region of the mitochondrial genome with incident, sporadic colorectal adenoma in three pooled colonoscopy-based case-control studies (n = 327 adenoma cases, 420 controls) that used identical methods for case and risk factor ascertainment. We sequenced a 1124 bp fragment to identify all genetic variation in the mitochondrial D-loop region, and used the Sequenom platform to genotype 64 tagSNPs in the non-D-loop region. We used multivariable unconditional logistic regression to estimate associations of the polymorphisms with adenoma. The odds ratios (OR) for associations of four polymorphisms in the HV1 region (mt16294, mt16296, mt16278, mt16069) with adenoma were 2.30, 2.63, 3.34, and 0.56, respectively; all 95% confidence intervals (CI) excluded 1.0, however, after correction for multiple comparisons, none of the findings remained statistically significant. Similar results were found for six polymorphisms in the non-D-loop region. In the HV1 region poly C tract, relative to those with 5 repeats, the ORs for those with fewer or more repeats were, respectively, 2.29 (95%CI 1.07-4.89) and 0.63 (95%CI 0.36-1.08), but repeat numbers in the HV2 region were not associated with adenoma. These findings suggest that mitochondrial D-loop HV1 region polymorphisms may be associated with colorectal adenoma risk and support further investigation.

Cardiovascular disease risk factors and oxidative stress among premenopausal women

Oxidative stress is one hypothesized mechanism linking anthropometric, behavioral, and medical risk factors with cardiovascular disease (CVD). We evaluated cross-sectional associations between CVD risk factors and biomarkers of oxidative stress, and investigated these biomarkers as predictors of incident diabetes and hypertension among premenopausal women. F₂-isoprostane (F₂-IsoP) and metabolite (15-F_2t-IsoP-M), reliable biomarkers of oxidative stress, were measured in urine samples collected at enrollment from 897 premenopausal women (ages 35-54) enrolled in the Sister Study cohort without a CVD history. Blood pressure, waist circumference, and body mass index (BMI) were measured at enrollment by trained study personnel. Diabetes and cigarette smoking were self-reported via enrollment questionnaires. Over a maximum follow-up of 11.5 years, participants self-reported incident diabetes and hypertension diagnoses on mailed questionnaires. In cross-sectional analyses, both F₂-IsoP and 15-F_2t-IsoP-M were positively associated with BMI, waist circumference, diastolic blood pressure, and current smoking. F₂-IsoP was elevated among those with diabetes, and 15-F_2t-IsoP-M increased with higher systolic blood pressure. Prospective analyses suggested an increased hypertension risk among those with elevated 15-F_2t-IsoP-M (highest vs. lowest quartile: hazard ratio=2.34; 95% CI: 1.20-4.56). Our results suggest that urinary F₂-IsoP and 15-F_2t-IsoP-M are positively associated with adiposity measures, blood pressure, and cigarette smoking. Further investigation is warranted to evaluate 15-F_2t-IsoP-M as a predictor of hypertension.

Dietary Glycemic Index and Glycemic Load Are Positively Associated with Oxidative Stress among Premenopausal Women

Background

Diets with a high glycemic index (GI) and glycemic load (GL) have been hypothesized to increase oxidative stress, but the limited human studies are inconsistent.

Objective

The aim of this cross-sectional study was to investigate associations between dietary GI, GL, and carbohydrate intake and oxidative stress, as measured by F2-isoprostanes (F2-IsoPs).

Methods

Concentrations of F2-IsoP and its metabolite (15-F2t-IsoP-M) were measured in urine samples collected at enrollment from 866 premenopausal women (aged 35-54 y) participating in the Sister Study. Total carbohydrate intake and dietary GI and GL were assessed using a validated food frequency questionnaire. Urinary F2-IsoP and 15-F2t-IsoP-M concentrations were compared across quintiles of carbohydrate intake, GI, and GL using multivariable linear regression models.

Results

Urinary F2-IsoP concentrations were positively associated with dietary GI (P-trend = 0.023), and both F2-IsoP and 15-F2t-IsoP-M concentrations were positively associated with GL (F2-IsoP: P-trend < 0.001; 15-F2t-IsoP-M: P-trend < 0.001) and total carbohydrate intake (F2-IsoP: P-trend = 0.012; 15-F2t-IsoP-M: P-trend < 0.001). Stratified analyses suggested that a positive association between GI and urinary 15-F2t-IsoP-M concentrations was present among women with a body mass index [BMI (in kg/m2)] ≥30.0, but not among those with a BMI of <25.0 or 25.0-29.9 (P-interaction = 0.01).

Conclusions

Our cross-sectional analyses in a sample of premenopausal women support hypothesized relations between high dietary GI and GL and oxidative stress, as assessed by urinary F2-IsoP and 15-F2t-IsoP-M concentrations. Given potential associations between oxidative stress and the development of cardiovascular disease and type 2 diabetes, our findings may have important implications for reducing chronic disease risk.

A Novel Application of Structural Equation Modeling Estimates the Association between Oxidative Stress and Colorectal Adenoma

In vitro evidence implicates oxidative stress in many adverse health conditions, including colorectal neoplasia. In human studies, however, oxidative stress is measured by imperfect biomarkers, which are inconsistently associated with health outcomes. Structural equation modeling (SEM) offers one possible solution by modeling a latent (unobserved) construct from multiple biomarkers. Our goal was to investigate the association of a latent oxidative stress variable with colorectal adenoma. Using SEM, we analyzed pooled data from two cross-sectional studies of colorectal adenoma (n = 526) that measured five plasma biomarkers of oxidative stress and inflammation that comprised the latent oxidative stress variable: F₂-isoprostanes (FIP), fluorescent oxidation products (FOP), mitochondrial DNA (MtDNA) copy number, γ-tocopherol (Gtoc), and C-reactive protein (CRP). Higher levels of oxidative stress were associated with colorectal adenoma [OR = 3.23 per SD increase in oxidative stress; 95% confidence interval (CI), 1.28-8.18]. The latent variable estimate was considerably stronger than the associations of adenoma with the individual biomarkers, which were modest and mostly nonsignificant. Risk factors were associated with adenoma via the oxidative stress pathway, particularly overweight and obesity with an OR = 1.50; 95% CI, 1.10-2.81; and OR = 2.95; 95% CI, 1.28-12.45, respectively. Oxidative stress may be positively associated with colorectal adenoma, and important risk factors may act through this mechanism, but the cross-sectional design of the current study precludes observing the directionality of associations. The presence of an adenoma could affect levels of the circulating biomarkers; thus, we should be cautious of strong conclusions until the findings are replicated in a follow-up study. Cancer Prev Res; 11(1); 52-58. ©2017 AACR.

The impact of obesity on brain iron levels and α-synuclein expression is regionally dependent

BACKGROUND

The importance of iron homeostasis is particularly apparent in the brain, where iron deficiency results in impaired cognition and iron accumulation is associated with neurodegenerative diseases. Obesity is linked to iron deficiency systemically, but the effects of obesity on brain iron and its associated consequences, including neurodegenerative processes remain unexplored. This preliminary study examined the effect of dietary-induced obesity on brain regional iron, α-synuclein expression, and F2-isoprostane (oxidative stress marker) concentrations in selected brain regions.

OBJECTIVE

The objective of the study was to elucidate the vulnerability of selected brain regions (e.g. midbrain, hippocampus) to the possible process of neurodegeneration due to the altered iron content associated with obesity.

METHODS

Twenty-one-day-old male C57BL/6J mice were fed with a high-fat diet (60% kcal from fat) or a control-fat diet (10% kcal from fat) for 20 weeks. Brain samples were collected and dissected into hippocampus, midbrain, striatum, and thalamus regions. Iron content, ferritin H (FtH) and α-synuclein protein and mRNA expressions, and F₂-isoprostane were measured in selected regions.

RESULTS

The results indicated that obesity caused significant differences in iron levels in the midbrain and thalamus, but not in the hippocampus or striatum, compared to control mice. Furthermore, markers of neurodegeneration (α-synuclein mRNA expression and F₂-isoprostanes) were increased in the midbrain.

DISCUSSION

These results support previous findings that brain iron metabolism responds to environmental stress in a regionally distinct manner and suggests that alterations in brain iron metabolism due to obesity may be relevant in neurodegeneration.

Circulating inflammation-resolving lipid mediators RvD1 and DHA are decreased in patients with acutely symptomatic carotid disease

BACKGROUND

Efficient biomarkers for early prediction and diagnosis of an acutely symptomatic carotid plaque rupture event are currently lacking, impairing the ability to diagnose and treat patients with an acute plaque rupture events in a timely fashion. Resolvins are endogenous inflammation-resolving lipid mediators that are induced by inflammatory insults. We hypothesized that resolvin and other lipid profiles in sera likely mark the process towards plaque rupture.

METHODS

Circulating lipids associated with plaque rupture events were quantitatively profiled via targeted mediator-lipidomics using ultraperformance liquid chromatography tandem mass spectrometry in patients with acutely symptomatic and asymptomatic carotid disease.

RESULTS

Resolvin D1 (RvD1, 82 ± 11pM vs. 152 ± 17pM, p = 0.001) and docosahexaenoic acid (DHA) (0.052 ± 0.007µM versus 0.076 ± 0.008µM, p = 0.025) levels are decreased in the sera of patients presenting with an acutely symptomatic carotid plaque rupture event (n = 21) compared to patients with asymptomatic (n = 24) high-grade carotid stenosis. Circulating arachidonic acid (AA) levels, however, were higher (0.429 ± 0.046µM versus 0.257 ± 0.035µM, p < 0.01) in acutely symptomatic compared to asymptomatic carotid patients. ROC curve analysis demonstrates that the serum ratio AA:RvD1 (AUC 0.84, sensitivity 0.71, specificity 0.92) and AA:DHA (AUC 0.86, sensitivity 0.90, specificity 0.71) are biomarkers for the risk of atherosclerotic plaque rupture.

CONCLUSIONS

A circulating pro-inflammatory lipid profile, characterized by high AA:RvD1 and AA:DHA, is associated with acutely symptomatic carotid disease and stroke.

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.

Plasma F2-isoprostanes Are Positively Associated with Glycemic Load, but Inversely Associated with Dietary Polyunsaturated Fatty Acids and Insoluble Fiber in Postmenopausal Women

Background: Dietary factors, such as antioxidant nutrients, contribute significantly to the maintenance of an appropriate balance between antioxidant defense and free radical production in the body.Objective: The objective of this study was to examine the relation between oxidative stress as assessed by plasma F₂-isoprostane (IsoP) concentration, glycemic load (GL), glycemic index (GI), intake of antioxidant nutrients, dietary fiber, and polyunsaturated fatty acids (PUFAs).Methods: This study was a cross-sectional secondary analysis of baseline data collected from a random sample of 269 postmenopausal women participating in the Minnesota Green Tea Trial. GL, GI, and dietary variables were calculated from the diet history questionnaire. Subjects filled out surveys about the use of anti-inflammatory drugs and physical activity. Plasma IsoP concentration was assessed by GC-mass spectrometry. IsoP concentrations were compared across quartiles of GL, GI, insoluble fiber, PUFAs, and antioxidant nutrients with the use of linear regression.Results: Antioxidant supplement intake, including zinc, copper, vitamin C and vitamin E, was reported by >60% of the participants. Mean intake of PUFAs was 12.5 g. Mean plasma IsoP concentrations increased from 34 to 36.7 pg/mL in the lowest quartiles of GL and GI, respectively, to 45.2 and 41.6 pg/mL, respectively, in the highest quartiles (P-trend = 0.0014 for GL and P-trend = 0.0379 for GI), whereas mean IsoP concentrations decreased from 41.8 pg/mL in the lowest quartile of PUFAs to 34.9 pg/mL in the highest quartile (P-trend = 0.0416). Similarly, mean IsoP concentrations decreased from 44.4 pg/mL in the lowest quartile of insoluble fiber to 36 pg/mL in the highest quartile (P-trend = 0.0243) after adjustment for potential confounders.Conclusions: We concluded that dietary PUFAs and insoluble fiber are inversely associated with oxidative stress whereas GL and GI are positively associated with oxidative stress in postmenopausal women. This trial was registered at clinicaltrials.gov as NCT00917735.

F2-Isoprostanes Reflect Oxidative Stress Correlated With Lean Mass and Bone Density but Not Insulin Resistance

Context:

F2-isoprostanes (F2-isoPs) are biomarkers for oxidative stress in humans and have been shown to be elevated in obesity, cardiovascular disease, and diabetes. Therefore, F2-isoPs are often implicated in oxidative stress contributing to insulin resistance, although this has not been rigorously examined.

Objective:

To determine whether urinary F2-isoPs are predictive of insulin sensitivity and other clinical metabolic parameters.

Participants:

Sedentary, weight-stable, nondiabetic adults equilibrated on a standard isocaloric diet.

Main Outcome Measures:

Insulin sensitivity via hyperinsulinemic-euglycemic clamp, urinary F2-isoPs by gas chromatography-mass spectrometry, and body composition by dual-energy x-ray absorptiometry.

Results:

No correlation was found between 15-F_2t-IsoP nor its major metabolite, 2,3-dinor-5,6-dihydro-15-F_2t-IsoP, with insulin sensitivity, even after adjusting for age, race, sex, BMI, and smoking status. 15-F_2t-IsoP was also not associated with body fat. However, there was a strong negative correlation between 15-F_2t-IsoP and lean body mass (LBM; r = −0.46, P = 0.0001), bone mineral content (BMC; r = −0.58, P < 0.0001), bone mineral density (BMD; r = −0.65, P < 0.0001), and skeletal muscle protein 4-hydroxynonenal (4-HNE; r = −0.54, P = 0.0239), another marker of oxidative stress. 15-F_2t-IsoP was also positively associated with circulating triglycerides and total cholesterol, and increased as a function of age.

Conclusions:

Urinary 15-F_2t-IsoP and its major metabolite are not associated with insulin sensitivity, suggesting the lipid peroxidation process that produces F2-isoPs does not reflect oxidative stress reactions operative in insulin resistance. However, urinary F2-isoPs were negatively correlated with LBM, BMC, BMD, and muscle 4-HNE. Because lean and bone mass decline as a function of biological aging, F2-isoPs may reflect the oxidative stress operative in the aging process.

Using multiple biomarkers and determinants to obtain a better measurement of oxidative stress: a latent variable structural equation model approach

PURPOSE

Since oxidative stress involves a variety of cellular changes, no single biomarker can serve as a complete measure of this complex biological process. The analytic technique of structural equation modeling (SEM) provides a possible solution to this problem by modelling a latent (unobserved) variable constructed from the covariance of multiple biomarkers.

METHODS

Using three pooled datasets, we modelled a latent oxidative stress variable from five biomarkers related to oxidative stress: F₂-isoprostanes (FIP), fluorescent oxidation products, mitochondrial DNA copy number, γ-tocopherol (Gtoc) and C-reactive protein (CRP, an inflammation marker closely linked to oxidative stress). We validated the latent variable by assessing its relation to pro- and anti-oxidant exposures.

RESULTS

FIP, Gtoc and CRP characterized the latent oxidative stress variable. Obesity, smoking, aspirin use and β-carotene were statistically significantly associated with oxidative stress in the theorized directions; the same exposures were weakly and inconsistently associated with the individual biomarkers.

CONCLUSIONS

Our results suggest that using SEM with latent variables decreases the biomarker-specific variability, and may produce a better measure of oxidative stress than do single variables. This methodology can be applied to similar areas of research in which a single biomarker is not sufficient to fully describe a complex biological phenomenon.

Aerobic exercise increases resistance to oxidative stress in sedentary older middle-aged adults. A pilot study

Older individuals who exercise regularly exhibit greater resistance to oxidative stress than their sedentary peers, suggesting that exercise can modify age-associated loss of resistance to oxidative stress. However, we recently demonstrated that a single bout of exercise confers protection against a subsequent oxidative challenge in young, but not older adults. We therefore hypothesized that repeated bouts of exercise would be needed to increase resistance to an oxidative challenge in sedentary older middle-aged adults. Sedentary older middle-aged men and women (50-63 years, n = 11) participated in an 8-week exercise intervention. Maximal oxygen consumption was measured before and after the intervention. The exercise intervention consisted of three sessions per week, for 45 min at an intensity corresponding to 70-85 % maximal heart rate (HR_max). Resistance to oxidative stress was measured by F₂-isoprostane response to a forearm ischemia/reperfusion (I/R) trial. Each participant underwent the I/R trial before and after the exercise intervention. The intervention elicited a significant increase in maximal oxygen consumption (VO_2max) (P < 0.0001). Baseline levels of F₂-isoprostanes pre- and post-intervention did not differ, but the F₂-isoprostane response to the I/R trial was significantly lower following the exercise intervention (time-by-trial interaction, P = 0.043). Individual improvements in aerobic fitness were associated with greater improvements in the F₂-isoprostane response (r = -0.761, P = 0.011), further supporting the role of aerobic fitness in resistance to oxidative stress. These data demonstrate that regular exercise with improved fitness leads to increased resistance to oxidative stress in older middle-aged adults and that this measure is modifiable in previously sedentary individuals.

Oxidative stress in relation to diet and physical activity among premenopausal women

Higher levels of oxidative stress, as measured by F2-isoprostanes, have been associated with chronic diseases such as CVD and some cancers. Improvements in diet and physical activity may help reduce oxidative stress; however, previous studies regarding associations between lifestyle factors and F2-isoprostane concentrations have been inconsistent. The aim of this cross-sectional study was to investigate whether physical activity and intakes of fruits/vegetables, antioxidant nutrients, dietary fat subgroups and alcohol are associated with concentrations of F2-isoprostane and the major F2-isoprostane metabolite. Urinary F2-isoprostane and its metabolite were measured in urine samples collected at enrolment from 912 premenopausal women (aged 35-54 years) participating in the Sister Study. Physical activity, alcohol consumption and dietary intakes were self-reported via questionnaires. With adjustment for potential confounders, the geometric means of F2-isoprostane and its metabolite were calculated according to quartiles of dietary intakes, alcohol consumption and physical activity, and linear regression models were used to evaluate trends. Significant inverse associations were found between F2-isoprostane and/or its metabolite and physical activity, vegetables, fruits, vitamin C, α-carotene, vitamin E, β-carotene, vitamin A, Se, lutein+zeaxanthin and long-chain n-3 fatty acids. Although trans fats were positively associated with both F2-isoprostane and its metabolite, other dietary fat subgroups including SFA, n-6 fatty acids, n-3 fatty acids, MUFA, PUFA, short-chain n-3 fatty acids, long-chain n-3 fatty acids and total fat were not associated with either F2-isoprostane or its metabolite. Our findings suggest that lower intake of antioxidant nutrients and higher intake of trans fats may be associated with greater oxidative stress among premenopausal women.

Smoking and red blood cell phospholipid membrane fatty acids

Smoking is associated with lower n-3 long chain polyunsaturated fatty acids (LCPUFA) concentrations; however, limited studies have accounted for dietary PUFA intake or whether tobacco dose or smoking duration influences this association. We measured red blood cell phospholipid (RBC) membrane concentrations of fatty acids in 126 current smokers, 311 former smokers, and 461 never smokers using gas liquid chromatography and tandem mass spectrometry. Smokers had lower RBC membrane percentages of total n-3 LCPUFAs compared to former smokers or never smokers (median percent: 5.46, [interquartile range (IQR) 4.52, 6.28] versus 6.39; [IQR: 5.18, 7.85] versus 6.59; [IQR 5.34, 8.01]) (p<0.001) and this association remained after adjusting for dietary PUFA intake. Duration of smoking and cigarettes per day were not associated with RBC membrane n-3 LCPUFA differences. Smoking is associated with lower n-3 LCPUFA RBC membrane percentages and this association was not influenced by diet or smoking dose or duration.

Increasing F2-isoprostanes in the first month after birth predicts poor respiratory and neurodevelopmental outcomes in very preterm infants

OBJECTIVE

This study examined the association between increased early oxidative stress, measured by F2-isoprostanes (IsoPs), and respiratory morbidity at term equivalent age and neurological impairment at 12 months of corrected age (CA).

STUDY DESIGN

Plasma samples were collected from 136 premature infants on days 14 and 28 after birth. All participants were infants born at ⩽28 weeks of gestational age enrolled into the Prematurity and Respiratory Outcomes Program (PROP) study. Respiratory morbidity was determined at 40 weeks of postmenstrual age (PMA) by the Respiratory Severity Index (RSI), a composite measure of oxygen and pressure support. Neurodevelopmental assessment was performed using the Developmental Assessment of Young Children (DAYC) at 12 months of CA. Multivariable logistic regression models estimated associations between IsoP change, RSI and DAYC scores. Mediation analysis was performed to determine the relationship between IsoPs and later outcomes.

RESULTS

Developmental data were available for 121 patients (90% of enrolled) at 12 months. For each 50-unit increase in IsoPs, regression modeling predicted decreases in cognitive, communication and motor scores of -1.9, -1.2 and -2.4 points, respectively (P<0.001). IsoP increase was also associated with increased RSI at 40 weeks of PMA (odds ratio=1.23; P=0.01). RSI mediated 25% of the IsoP effect on DAYC motor scores (P=0.02) and had no significant impact on cognitive or communication scores.

CONCLUSIONS

In the first month after birth, increases in plasma IsoPs identify preterm infants at risk for respiratory morbidity at term equivalent age and worse developmental outcomes at 12 months of CA. Poor neurodevelopment is largely independent of respiratory morbidity.

Liver specific expression of Cu/ZnSOD extends the lifespan of Sod1 null mice

Genetic ablation of CuZn-superoxide dismutase (Sod1) in mice (Sod1(-/-) mice) leads to shortened lifespan with a dramatic increase in hepatocellular carcinoma and accelerated aging phenotypes, including early onset sarcopenia. To study the tissue specific effects of oxidative stress in the Sod1(-/-) mice, we generated mice that only express the human SOD1 gene specifically in the liver of Sod1(-/-) mice (Sod1(-/-)/hSOD1(alb) mice). Expression of hSOD1 in the liver of Sod1(-/-) mice improved liver function, reduced oxidative damage in liver, and partially restored the expression of several genes involved in tumorigenesis, which are abnormally expressed in the livers of the Sod1(-/-) mice. However, liver specific expression of hSOD1 did not prevent the loss of body weight and muscle mass and alterations in the structure of neuromuscular junctions. The expression of hSOD1 in the liver of Sod1(-/-) mice significantly improved the lifespan of Sod1(-/-) mice; however, the lifespan of the Sod1(-/-)/hSOD1(alb) mice was still significantly shorter than wild type mice.

Oxidative stress, anti-oxidants and the cross-sectional and longitudinal association with depressive symptoms: results from the CARDIA study

Depression may be accompanied by increased oxidative stress and decreased circulating anti-oxidants. This study examines the association between depressive symptoms, F2-isoprostanes and carotenoids in a US community sample. The study includes 3009 participants (mean age 40.3, 54.2% female) from CARDIA (Coronary Artery Risk Development in Young Adults). Cross-sectional analyses were performed on data from the year 15 examination (2000-2001) including subjects whose depressive symptoms were assessed with the Center for Epidemiologic Studies Depression Scale (CES-D) and had measurements of plasma F2-isoprostanes (gas chromatography/mass spectrometry) or serum carotenoids (high-performance liquid chromatography). Carotenoids zeaxanthin/lutein, β-cryptoxanthin, lycopene, α-carotene, β-carotene were standardized and summed. Longitudinal analyses were conducted using the data from other examinations at 5-year intervals. Cross-lagged analyses investigated whether CES-D predicted F2-isoprostanes or carotenoids at the following exam, and vice versa. Regression analyses were controlled for sociodemographics, health and lifestyle factors. F2-isoprostanes were higher in subjects with depressive symptoms (CES-D ⩾ 16) after adjustment for sociodemographics (55.7 vs 52.0 pg ml(-1); Cohen's d = 0.14, P < 0.001). There was no difference in F2-isoprostanes after further adjustment for health and lifestyle factors. Carotenoids were lower in those with CES-D scores ⩾ 16, even after adjustment for health and lifestyle factors (standardized sum 238.7 vs 244.0, Cohen's d = -0.16, P < 0.001). Longitudinal analyses confirmed that depression predicts subsequent F2-isoprostane and carotenoid levels. Neither F2-isoprostanes nor carotenoids predicted subsequent depression. In conclusion, depressive symptoms were cross-sectionally and longitudinally associated with increased F2-isoprostanes and decreased carotenoids. The association with F2-isoprostanes can largely be explained by lifestyle factors, but lower carotenoids were independently associated with depressive symptoms.

Age-related cellular changes in the long-lived bivalve A. islandica

One of the biggest challenges to studying causes and effects of aging is identifying changes in cells that are related to senescence instead of simply the passing of chronological time. We investigated two populations of the longest living non-colonial metazoan, Arctica islandica, with lifespans that differed sixfolds. Of four investigated parameters (nucleic acid oxidation, protein oxidation, lipid oxidation, and protein instability), only nucleic acid oxidation increased with age and correlated with relative lifespan. Nucleic acid oxidation levels increased significantly faster and were significantly higher in the shorter-lived than the longer-lived population. In contrast, neither protein oxidation, lipid oxidation, nor protein stability changed over time. Protein resistance to unfolding stress when treated with urea was significantly lower overall in the shorter-lived population, and lipid peroxidation levels were higher in the longer-lived population. With the exception of nucleic acid oxidation, damage levels of A. islandica do not change with age, indicating excellent cellular maintenance in both populations. Since correlations between nucleic acid oxidation and age have also been shown previously in other organisms, and nucleic acid oxidation accumulation rate correlates with relative age in both investigated populations, nucleic acid oxidation may reflect intrinsic aging mechanisms.

Timing of solid food introduction is associated with urinary F2-isoprostane concentrations in childhood

BACKGROUND

Timing of solid food introduction in infancy has been associated with several chronic diseases. To explore potential mechanisms, we investigated the relationship between timing of solid food introduction and F2-isoprostanes-a marker of oxidative stress.

METHODS

Urinary F2-isoprostanes were assessed in 336 healthy children aged less than 11.5 y with 1,266 clinic visits (mean = 3.8 visits per child) in the Diabetes Autoimmunity Study in the Young. We analyzed the association between F2-isoprostane concentrations and infant diet exposures using linear mixed models adjusted for age, age(2), HLA-DR3/4,DQB1*0302 genotype, first-degree relative with type 1 diabetes, maternal age, maternal education, sex, and exposure to in utero cigarette smoke.

RESULTS

Later solid food introduction was associated with lower F2-isoprostane concentrations in childhood (on average, 0.10 ng/mg per month of age at introduction; estimate: -0.10 (95% confidence interval (CI): -0.18, -0.02) P value = 0.02). Moreover, childhood F2-isoprostane concentrations were, on average, 0.24 ng/mg lower in individuals breastfed at solid food introduction (estimate: -0.24 (95% CI: -0.47, -0.01) P value = 0.04) compared with those who were not. Associations remained significant after limiting analyses to F2-isoprostanes after 2 y of age.

CONCLUSION

Our results suggest a long-term protective effect of later solid food introduction and breastfeeding at solid food introduction against increased F2-isoprostane concentrations throughout childhood.

Clinical Application of NOX Activity and Other Oxidative Biomarkers in Cardiovascular Disease: A Critical Review

SIGNIFICANCE

The oxidative stress theory of atherosclerosis is based on the assumption that the production of reactive oxidant species (ROS) by blood, as well as resident cells of the artery wall, elicits the formation of oxidized low-density lipoproteins (ox-LDL), which, in turn, promotes a series of inflammatory responses, ultimately leading to atherosclerotic plaque. This theory prompted the development of new laboratory methodologies that aimed at assessing the relationship between oxidative stress and clinical progression of human atherosclerosis.

CRITICAL ISSUES

Markers assessing the oxidation of phospholipid and protein components of LDL were among the first to be developed. Clinical trials included cross-sectional as well as retrospective and prospective studies that, however, provided equivocal results. Thus, clear evidence that oxidative biomarkers add more to the risk stratification by common atherosclerotic risk factors is still lacking.

RECENT ADVANCES

More recently, the analysis of oxidative stress focused on enzymatic pathways generating ROS, such as NADPH oxidase and myeloperoxidase (MPO). Experimental and clinical studies suggest that both enzymes may be implicated in promoting atherosclerotic disease. Novel laboratory methodologies have been, therefore, developed to study NADPH oxidase and MPO in patients with stable atherosclerosis as well as in patients with acute coronary and cerebro-vascular syndromes.

FUTURE DIRECTIONS

This review will analyze the strengths and weaknesses of the current methodology to study these enzymes in human atherosclerosis with particular regard to their clinical application in several settings of cardiovascular disease. Clinical methodology and results of previous studies with regard to markers of LDL oxidation have also been reviewed as a useful background for the future development of clinical trials.

Effects of EGCG content in green tea extract on pharmacokinetics, oxidative status and expression of inflammatory and apoptotic genes in the rat ocular tissues

Green tea extract (GTE) exerts antioxidative activities in ocular tissues of rats, but high levels of (-)-epigallocatechin gallate (EGCG) can induce oxidative stress. In this study, pharmacokinetics, diurnal variation of oxidative status, antioxidation and transcription factors changes in ocular tissues of rats were investigated. Rats were fed intragastrically with GTE and catechin mixtures containing different amounts of EGCG. Plasma and various ocular tissues were taken for pharmacokinetic analysis, oxidation marker testings and gene expression assays. Effects of EGCG on ocular oxidation status were assessed by 8-isoprostane level and reduced/oxidized glutathione ratio. Oxidation, inflammation and apoptosis regulations in retina were evaluated by real-time polymerase chain reaction. Epicatechin, epigallocatechin and EGCG were dominant in various ocular tissues except vitreous humor, where gallocatechin was predominant. Diurnal variation of oxidative status was found in some compartments. GTE caused oxidative stress increase in the plasma, aqueous humor, vitreous humor, cornea and retina but decrease in the lens and choroid-sclera. Catechins mixture containing half dose of EGCG lowered 8-isoprostane in the retina and lens. GTE treatment induced superoxide dismutase 1 and glutathione peroxidase-3 expressions but suppressed catalase in the retina. Our results reveal pro-oxidation of GTE with high EGCG content to the ocular tissues. Optimal EGCG level is needed for protection.

Positive psychiatry: its time has come

Traditionally, psychiatry has been defined and practiced as a branch of medicine focused on the diagnosis and treatment of mental illnesses. Based on growing empirical evidence, we believe that this definition warrants expansion to include the concept of positive psychiatry. In the present article, we provide a critical overview of this emerging field and a select review of relevant scientific literature. Positive psychiatry may be defined as the science and practice of psychiatry that seeks to understand and promote well-being through assessment and interventions involving positive psychosocial characteristics (PPCs) in people who suffer from or are at high risk of developing mental or physical illnesses. It can also benefit nonclinical populations. Positive psychiatry has 4 main components: (1) positive mental health outcomes (eg, well-being), (2) PPCs that comprise psychological traits (resilience, optimism, personal mastery and coping self-efficacy, social engagement, spirituality and religiosity, and wisdom-including compassion) and environmental factors (family dynamics, social support, and other environmental determinants of overall health), (3) biology of positive psychiatry constructs, and (4) positive psychiatry interventions including preventive ones. There are promising empirical data to suggest that positive traits may be improved through psychosocial and biological interventions. As a branch of medicine rooted in biology, psychiatry, especially with the proposed conceptualization of positive psychiatry, is well poised to provide major contributions to the positive mental health movement, thereby impacting the overall health care of the population.

The effect of mild traumatic brain injury on peripheral nervous system pathology in wild-type mice and the G93A mutant mouse model of motor neuron disease

Traumatic brain injury (TBI) is associated with a risk of neurodegenerative disease. Some suggest a link between TBI and motor neuron disease (MND), including amyotrophic lateral sclerosis (ALS). To investigate the potential mechanisms linking TBI to MND, we measured motor function and neuropathology following mild-TBI in wild-type and a transgenic model of ALS, G93A mutant mice. Mild-TBI did not alter the lifespan of G93A mice or age of onset; however, rotarod performance was impaired in G93A verses wild-type mice. Grip strength was reduced only in G93A mice after mild-TBI. Increased electromyography (EMG) abnormalities and markers of denervation (AchR, Runx1) indicate that mild-TBI may result in peripheral effects that are exaggerated in G93A mice. Markers of inflammation (cell edema, astrogliosis and microgliosis) were detected at 24 and 72h in the brain and spinal cord in wild-type and G93A mice. Levels of F2-isoprostanes, a marker of oxidative stress, were increased in the spinal cord 24h post mild-TBI in wild-type mice but were not affected by TBI in G93A mice. In summary, our data demonstrate that mild-TBI induces inflammation and oxidative stress and negatively impacts muscle denervation and motor performance, suggesting mild-TBI can potentiate motor neuron pathology and influence the development of MND in mice.

Protocols for the measurement of the F2-isoprostane, 15(S)-8-iso-prostaglandin F2α, in biological samples by GC-MS or GC-MS/MS coupled with immunoaffinity column chromatography

Arachidonic acid, the origin of the eicosanoids family, occurs in biological samples as free acid and as ester in lipids. Free arachidonic acid is oxidized to numerous metabolites by means of enzymes including cyclooxygenase (COX). Arachidonic acid esterified to lipids is attacked by reactive oxygen species (ROS) to generate numerous oxidized arachidonic acid derivatives. Generally, it is assumed that ROS-derived arachidonic acid derivatives are distinct from those generated by enzymes such as COX. Therefore, ROS-generated eicosanoids are considered specific biomarkers of oxidative stress. However, there are serious doubts concerning a strict distinction between the enzyme-derived eicosanoids and the ROS-derived iso-eicosanoids. Prominent examples are prostaglandin F2α (PGF2α) and 15(S)-8-iso-prostaglandin F2α (15(S)-8-iso-PGF2α) which have been originally considered to exclusively derive from COX and ROS, respectively. There is convincing evidence that both COX and ROS can oxidize arachidonic acid to PGF2α and 15(S)-8-iso-PGF2α. Thus, many results previously reported for 15(S)-8-iso-PGF2α as exclusive ROS-dependent reaction product, and consequently as a specific biomarker of oxidative stress, require a careful re-examination which should also consider the analytical methods used to measure 15(S)-8-iso-PGF2α. This prominent but certainly not the only example underlines more than ever the importance of the analytical chemistry in basic and clinical research areas of oxidative stress. In the present work, we report analytical protocols for the reliable quantitative determination of 15(S)-8-iso-PGF2α in human biological samples including plasma and urine by mass spectrometry coupled to gas chromatography (GC-MS, GC-MS/MS) after specific isolation of endogenous 15(S)-8-iso-PGF2α and the externally added internal standard [3,3',4,4'-(2)H4]-15(S)-8-iso-PGF2α by immunoaffinity column chromatography (IAC). 15(S)-8-iso-PGF2α esterified to plasma lipids is hydrolysed by KOH. 15(S)-8-iso-PGF2α and [3,3',4,4'-(2)H4]-15(S)-8-iso-PGF2α are analyzed as pentafluorobenzyl ester trimethylsilyl ether derivatives in the electron-capture negative-ion chemical ionization mode.

Acute exercise increases resistance to oxidative stress in young but not older adults

A single bout of acute exercise increases oxidative stress and stimulates a transient increase in antioxidant enzymes. We asked whether this response would induce protection from a subsequent oxidative challenge, different from that of exercise, and whether the effects were affected by aging. We compared young (20 ± 1 years, n = 8) and older (58 ± 6 years, n = 9) healthy men and women. Resistance to oxidative stress was measured by the F2-isoprostane response to forearm ischemia/reperfusion (I/R) trial. Each participant underwent the I/R trial twice, in random order; once after performing 45 min of cycling on the preceding day (IRX) and a control trial without any physical activity (IRC). Baseline F2-isoprostane levels were significantly lower at IRX compared to IRC (P < 0.05) and not different between groups. F2-isoprostane response to IRX was significantly lower compared to IRC in young (P < 0.05) but not different in the older group. Superoxide dismutase activity in response to acute exercise was significantly higher in young compared to older adults (P < 0.05). These data suggest that signal transduction of acute exercise may be impaired with aging. Repeated bouts of transient reactive oxygen species production as seen with regular exercise may be needed to increase resistance to oxidative stress in older individuals.

F3-Isoprostanes as a Measure of in vivo Oxidative Damage in Caenorhabditis elegans

Oxidative stress has been implicated in the development of a wide variety of disease processes, including cardiovascular disease, cancer, and neurodegenerative diseases, as well as progressive and normal aging processes. Isoprostanes (IsoPs) are prostaglandin-like compounds that are generated in vivo from lipid peroxidation of arachidonic acid (AA, C20:4, ω-6) and other polyunsaturated fatty acids (PUFA). Since the discovery of IsoPs by Morrow and Roberts in 1990, quantification of IsoPs has been shown to be an excellent source of biomarkers of in vivo oxidative damage. Eicosapentaenoic acid (EPA, C20:5, ω-3) is the most abundant PUFA in Caenorhabditis elegans and gives rise to F3-IsoPs upon nonenzymatic free-radical-catalyzed lipid peroxidation. The protocol presented is the current methodology that our laboratory uses to quantify F3-IsoPs in C. elegans using gas chromatography/mass spectrometry (GC/MS). The methods described herein have been optimized and validated to provide the best sensitivity and selectivity for quantification of F3-IsoPs from C. elegans lysates.

Consumption of a high glycemic load but not a high glycemic index diet is marginally associated with oxidative stress in young women

Research studies have suggested that chronic consumption of high glycemic index foods may lead to chronically high oxidative stress. This is important because oxidative stress is suspected to be an early event in the etiology of many disease processes. We hypothesized that dietary glycemic index and glycemic load were positively associated with oxidative stress assessed by plasma F2-isoprostanes in healthy, premenopausal women (body mass index [BMI] = 24.7 ± 4.8 kg/m(2) and age 25.3 ± 3.5 years, mean ± SD). We measured plasma F2-isoprostanes in 306 healthy premenopausal women at the baseline visit for the Women In Steady Exercise Research study, using gas chromatography-mass spectrometry. Dietary glycemic index and load were calculated from the National Cancer Institute Diet History Questionnaire, and participants were divided into quartiles of dietary glycemic index and of glycemic load. Plasma F2-isoprostanes were compared across quartile groups of dietary glycemic index and glycemic load using linear regression models. Plasma F2-isoprostanes (pg/mL) increased with quartile of glycemic load (test for linear trend, P = .033), and also increased with quartile of glycemic index in participants with BMI ≥ 25 (P = .035) but not in those with BMI <25 (P = .924). After adjustment for BMI, alcohol consumption and total energy intake, both these positive trends remained marginally significant (P = .123 for quartiles of glycemic index and P = .065 for quartiles of glycemic load).

Efficacy of paracetamol on patent ductus arteriosus closure may be dose dependent: evidence from human and murine studies

BACKGROUND

We evaluated the clinical effectiveness of variable courses of paracetamol on patent ductus arteriosus (PDA) closure and examined its effect on the in vitro term and preterm murine ductus arteriosus (DA).

METHODS

Neonates received one of the following three paracetamol regimens: short course of oral paracetamol (SCOP), long course of oral paracetamol (LCOP), and intravenous paracetamol (IVP) for 2-6 d. Pressure myography was used to examine changes in vasomotor tone of the preterm and term mouse DA in response to paracetamol or indomethacin. Their effect on prostaglandin synthesis by DA explants was measured by mass spectroscopy.

RESULTS

Twenty-one preterm infants were included. No changes in PDA hemodynamics were seen in SCOP infants (n = 5). The PDA became less significant and eventually closed in six LCOP infants (n = 7). PDA closure was achieved in eight IVP infants (n = 9). On pressure myograph, paracetamol induced a concentration-dependent constriction of the term mouse DA, up to 30% of baseline (P < 0.01), but required >1 µmol/l. Indomethacin induced greater DA constriction and suppression of prostaglandin synthesis (P < 0.05).

CONCLUSION

The clinical efficacy of paracetamol on PDA closure may depend on the duration of treatment and the mode of administration. Paracetamol is less potent than indomethacin for constriction of the mouse DA in vitro.

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.

Matrix effect in F₂-isoprostanes quantification by HPLC-MS/MS: a validated method for analysis of iPF₂α-III and iPF₂α-VI in human urine

Liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) has become the method of choice for analysis in biological matrices, because of its high specificity and sensitivity. However, it should be taken into account that the presence of matrix components coeluting with analytes might interfere with the ionization process and affect the accuracy and precision of the assay. For this reason, the presence of a "matrix effect" should always be evaluated during method development, above all in complex matrix such as urine. In the present work, a HPLC-MS/MS method was developed for the quantification of urinary iPF2α-III and iPF2α-VI. A careful assessment of matrix effect and an accurate validation were carried out, in order to verify the reliability of quantitative data obtained. Ion suppression, due to the matrix components, was reduced through optimization of both chromatographic method and sample extraction procedure. Urine samples were purified by solid phase extraction (SPE) and the extracts injected into the HPLC-MS/MS system, equipped with a TurboIonSpray ionization source operated in negative ion mode (ESI(-)). Stable isotope-labeled analogues (iPF2α-III-d4 and iPF2α-VI-d4) were used as internal standards, and quantification was performed in multiple reaction monitoring (MRM) mode by monitoring the following mass transitions: m/z 353.4→193.2 for iPF2α-III, m/z 357.2→197.0 for iPF2α-III-d4, m/z 353.4→115.1 for iPF2α-VI, and m/z 357.4→115.1 for iPF2α-VI-d4. The validated assay, applied to the analysis of urinary samples coming from healthy and overweight subjects, resulted suitable for an accurate quantification of iPF2α-III and iPF2α-VI in human urine.

Microwave & Magnetic (M2) Proteomics of a Mouse Model of Mild Traumatic Brain Injury

Short-term increases in oxidative stress and decreases in motor function, including debilitating effects on balance and motor control, can occur following primary mild traumatic brain injuries (mTBI). However, the long-term effects on motor unit impairment and integrity as well as the molecular mechanisms underlying secondary injuries are poorly understood. We hypothesized that changes in central nervous system-specific protein (CSP) expression might correlate to these long-term effects. To test our hypothesis, we longitudinally assessed a closed-skull mTBI mouse model, vs. sham control, at 1, 7, 30, and 120 days post-injury. Motor impairment was determined by rotarod and grip strength performance measures, while motor unit integrity was determined using electromyography. Relative protein expression was determined by microwave & magnetic (M²) proteomics of ipsilateral brain tissue, as previously described. Isoprostane measurements were performed to confirm a primary oxidative stress response. Decoding the relative expression of 476 ± 56 top-ranked proteins for each specimen revealed statistically significant changes in the expression of two well-known CSPs at 1, 7 and 30 days post-injury: P < 0.001 for myelin basic protein (MBP) and P < 0.05 for myelin associated glycoprotein (MAG). This was confirmed by Western blot. Moreover, MAG, αII-spectrin (SPNA2) and neurofilament light (NEFL) expression at 30 days post-injury were directly related to grip strength (P < 0.05). While higher-powered studies of larger cohorts merit further investigation, this study supports the proof-of-concept that M² proteomics is a rapid method to quantify putative protein biomarkers and therapeutic targets of mTBI and suggests the feasibility of CSP expression correlations to long-term effects on motor impairment.

Plasma 15-F2t-isoprostane in idiopathic pulmonary arterial hypertension

BACKGROUND

15-F2t-isoprostane (15-F2t-IsoP), a prostaglandin F2-like compound, is widely recognized as a biomarker of chronic heart failure. This study investigated the potential role and prognostic significance of plasma 15-F2t-IsoP in patients with idiopathic pulmonary arterial hypertension (IPAH).

METHODS

Plasma 15-F2t-IsoP concentrations were determined in 80 consecutive IPAH patients at the time of their first right heart catheterization, and monitored for 30±12 months. The expression of 15-F2t-IsoP protein in autopsy lung samples was determined by immunohistochemical staining.

RESULTS

Plasma 15-F2t-IsoP concentrations were significantly increased in patients with IPAH compared with healthy controls (91 pg/ml vs. 30 pg/ml, respectively; P<0.001). Patients with baseline 15-F2t-IsoP concentrations≥97 pg/ml had a significantly lower survival rate than those with lower baseline concentrations (P<0.001). During follow-up, 15-F2t-IsoP concentrations in survivors decreased, whereas concentrations in non-surviving patients increased further (P<0.05). Elevated concentrations of 15-F2t-IsoP were correlated with a severity of WHO functional class, lower 6-minute walking distance and mixed venous oxygen saturation, higher mean right atrial pressure and brain natriuretic peptide. Multivariate analysis revealed that the plasma 15-F2t-IsoP concentration was an independent factor associated with mortality. Histological studies showed that the expression of 15-F2t-IsoP was up-regulated in remodeled pulmonary vessels.

CONCLUSIONS

An elevated plasma 15-F2t-IsoP concentration and a further increase during follow-up may be a risk factor for higher mortality in patients with IPAH.

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.