An improved method for the measurement of urinary and plasma F2-isoprostanes using gas chromatography-mass spectrometry

Dietary iron enhances colonic inflammation and IL-6/IL-11-Stat3 signaling promoting colonic tumor development in mice

Chronic intestinal inflammation and high dietary iron are associated with colorectal cancer development. The role of Stat3 activation in iron-induced colonic inflammation and tumorigenesis was investigated in a mouse model of inflammation-associated colorectal cancer. Mice, fed either an iron-supplemented or control diet, were treated with azoxymethane and dextran sodium sulfate (DSS). Intestinal inflammation and tumor development were assessed by endoscopy and histology, gene expression by real-time PCR, Stat3 phosphorylation by immunoblot, cytokines by ELISA and apoptosis by TUNEL assay. Colonic inflammation was more severe in mice fed an iron-supplemented compared with a control diet one week post-DSS treatment, with enhanced colonic IL-6 and IL-11 release and Stat3 phosphorylation. Both IL-6 and ferritin, the iron storage protein, co-localized with macrophages suggesting iron may act directly on IL-6 producing-macrophages. Iron increased DSS-induced colonic epithelial cell proliferation and apoptosis consistent with enhanced mucosal damage. DSS-treated mice developed anemia that was not alleviated by dietary iron supplementation. Six weeks post-DSS treatment, iron-supplemented mice developed more and larger colonic tumors compared with control mice. Intratumoral IL-6 and IL-11 expression increased in DSS-treated mice and IL-6, and possibly IL-11, were enhanced by dietary iron. Gene expression of iron importers, divalent metal transporter 1 and transferrin receptor 1, increased and iron exporter, ferroportin, decreased in colonic tumors suggesting increased iron uptake. Dietary iron and colonic inflammation synergistically activated colonic IL-6/IL-11-Stat3 signaling promoting tumorigenesis. Oral iron therapy may be detrimental in inflammatory bowel disease since it may exacerbate colonic inflammation and increase colorectal cancer risk.

Effects of low-fat or full-fat fermented and non-fermented dairy foods on selected cardiovascular biomarkers in overweight adults

The association between consumption of full-fat dairy foods and CVD may depend partly on the nature of products and may not apply to low-fat dairy foods. Increased circulating levels of inflammatory biomarkers after consumption of dairy product-rich meals suggest an association with CVD. In the present study, we tested the effects of low-fat and full-fat dairy diets on biomarkers associated with inflammation, oxidative stress or atherogenesis and on plasma lipid classes. Within full-fat dairy diets, we also compared fermented v. non-fermented products. In a randomised cross-over study, twelve overweight/obese subjects consumed during two 3-week periods two full-fat dairy diets containing either yogurt plus cheese (fermented) or butter, cream and ice cream (non-fermented) or a low-fat milk plus yogurt diet, with the latter being consumed between and at the end of the full-fat dairy dietary periods. The concentrations of six inflammatory and two atherogenic biomarkers known to be raised in CVD were measured as well as those of plasma F2-isoprostanes and lipid classes. The concentrations of six of the eight biomarkers tended to be higher on consumption of the low-fat dairy diet than on that of the fermented dairy diet and the concentrations of two plasmalogen lipid classes reported to be associated with increased oxidisability were also higher on consumption of the low-fat dairy diet than on that of the fermented dairy diet (P< 0.001), although plasma F2-isoprostane concentrations did not differ on consumption of any of the diets. On the other hand, the concentrations of plasma sphingomyelin and IL-6 were significantly higher on consumption of the non-fermented dairy diet than on that of the low-fat dairy diet (P< 0.02). In conclusion, short-term diets containing low-fat dairy products did not lead to a more favourable biomarker profile associated with CVD risk compared with the full-fat dairy products, suggesting that full-fat fermented dairy products may be the more favourable.

The effect of alpha-lipoic acid on mitochondrial superoxide and glucocorticoid-induced hypertension

Aims. To examine the effect of alpha-lipoic acid, an antioxidant with mitochondrial superoxide inhibitory properties, on adrenocorticotrophic hormone- (ACTH-HT) and dexamethasone-induced hypertensions (DEX-HT) in rats and if any antihypertensive effect is mediated via mitochondrial superoxide inhibition. Methods. In a prevention study, rats received ground food or alpha-lipoic-acid-laced food (10 mg/rat/day) for 15 nights. Saline, adrenocorticotrophic hormone (ACTH, 0.2 mg/kg/day), or dexamethasone (DEX, 10 μg/rat/day) was injected subcutaneously from day 5 to day 11. In a reversal study, rats received alpha-lipoic-acid-laced food 4 days after commencement of saline or DEX. Tail-cuff systolic blood pressure (SBP) was measured second daily. Kidney mitochondrial superoxide was examined using (MitoSOX) Red (MitoSOX) via flow cytometry. Results. SBP was increased by ACTH (P < 0.0005) and DEX (P < 0.0005). Alpha-lipoic acid alone did not alter SBP. With alpha-lipoic acid pretreatment, SBP was increased by ACTH (P′ < 0.005) but not by DEX. Alpha-lipoic partially prevented ACTH-HT (P′ < 0.0005) and fully prevented DEX-HT (P′ < 0.0005) but failed to reverse DEX-HT. ACTH and DEX did not increase MitoSOX signal. In ACTH-hypertensive rats, high-dose alpha-lipoic acid (100 mg/rat/day) did not decrease SBP further but raised MitoSOX signal (P < 0.001), suggesting prooxidant activity. Conclusion. Glucocorticoid-induced hypertension in rats is prevented by alpha-lipoic acid via mechanisms other than mitochondrial superoxide reduction.

Effect of supplemental oxygen on post-exercise inflammatory response and oxidative stress

This investigation explored the influence of supplemental oxygen administered during the recovery periods of an interval-based running session on the post-exercise markers of reactive oxygen species (ROS) and inflammation. Ten well-trained male endurance athletes completed two sessions of 10 × 3 min running intervals at 85 % of the maximal oxygen consumption velocity (vVO(2)peak) on a motorised treadmill. A 90-s recovery period was given between each interval, during which time the participants were administered either a hyperoxic (HYP) (Fraction of Inspired Oxygen (FIO2) 99.5 %) or normoxic (NORM) (FIO2 21 %) gas, in a randomized, single-blind fashion. Pulse oximetry (SpO(2)), heart rate (HR), blood lactate (BLa), perceived exertion (RPE), and perceived recovery (TQRper) were recorded during each trial. Venous blood samples were taken pre-exercise, post-exercise and 1 h post-exercise to measure Interleukin-6 (IL-6) and Isoprostanes (F2-IsoP). The S(p)O(2) was significantly lower than baseline following all interval repetitions in both experimental trials (p < 0.05). The S(p)O(2) recovery time was significantly quicker in the HYP when compared to the NORM (p < 0.05), with a trend for improved perceptual recovery. The IL-6 and F2-IsoP were significantly elevated immediately post-exercise, but had significantly decreased by 1 h post-exercise in both trials (p < 0.05). There were no differences in IL-6 or F2-IsoP levels between trials. Supplemental oxygen provided during the recovery periods of interval based exercise improves the recovery time of SPO(2) but has no effect on post-exercise ROS or inflammatory responses.

An efficient sample preparation method for high-throughput analysis of 15(S)-8-iso-PGF2α in plasma and urine by enzyme immunoassay

Although several methods have been reported on the analysis of the oxidative stress marker 15(S)-8-iso-prostaglandin-F2alpha (8-iso-PGF2α) in biological fluids, they either involve extensive sample preparation and costly technology or require high sample volume. This study presents a sample preparation method that utilizes low sample volume for 8-iso-PGF2α analysis in plasma and urine by an enzyme immunoassay (EIA). In brief, 8-iso-PGF2α in deproteinized plasma or native urine sample is complexed with an antibody and then captured by molecular weight cut-off filtration. This method was compared with two other sample preparation methods that are typically used in the analysis of 8-iso-PGF2α by EIA: Cayman's affinity column purification method and solid-phase extraction on C-18. The immunoaffinity purification method described here was superior to the other two sample preparation methods and yielded recovery values of 99.8 and 54.1% for 8-iso-PGF2α in plasma and urine, respectively. Analytical precision (relative standard deviation) was ±5% for plasma and ±15% for urine. The analysis of healthy human plasma and urine resulted in basal 8-iso-PGF2α levels of 31.8 ± 5.5 pg/mL and 2.9 ± 2.0 ng/mg creatinine, respectively. The robustness and analytical performance of this method makes it a promising tool for high-throughput screening of biological samples for 8-iso-PGF2α.

Disruption of hemochromatosis protein and transferrin receptor 2 causes iron-induced liver injury in mice

Mutations in hemochromatosis protein (HFE) or transferrin receptor 2 (TFR2) cause hereditary hemochromatosis (HH) by impeding production of the liver iron-regulatory hormone, hepcidin (HAMP). This study examined the effects of disruption of Hfe or Tfr2, either alone or together, on liver iron loading and injury in mouse models of HH. Iron status was determined in Hfe knockout (Hfe(-/-)), Tfr2 Y245X mutant (Tfr2(mut)), and double-mutant (Hfe(-/-) ×Tfr2(mut) ) mice by measuring plasma and liver iron levels. Plasma alanine transaminase (ALT) activity, liver histology, and collagen deposition were evaluated to assess liver injury. Hepatic oxidative stress was assessed by measuring superoxide dismutase (SOD) activity and F(2)-isoprostane levels. Gene expression was measured by real-time polymerase chain reaction. Hfe(-/-) ×Tfr2(mut) mice had elevated hepatic iron with a periportal distribution and increased plasma iron, transferrin saturation, and non-transferrin-bound iron, compared with Hfe(-/-), Tfr2(mut), and wild-type (WT) mice. Hamp1 expression was reduced to 40% (Hfe(-/-) and Tfr2(mut) ) and 1% (Hfe(-/-) ×Tfr2(mut)) of WT values. Hfe(-/-) ×Tfr2(mut) mice had elevated plasma ALT activity and mild hepatic inflammation with scattered aggregates of infiltrating inflammatory cluster of differentiation 45 (CD45)-positive cells. Increased hepatic hydoxyproline levels as well as Sirius red and Masson's Trichrome staining demonstrated advanced portal collagen deposition. Hfe(-/-) and Tfr2(mut) mice had less hepatic inflammation and collagen deposition. Liver F(2) -isoprostane levels were elevated, and copper/zinc and manganese SOD activities decreased in Hfe(-/-) ×Tfr2(mut), Tfr2(mut), and Hfe(-/-) mice, compared with WT mice.

CONCLUSION

Disruption of both Hfe and Tfr2 caused more severe hepatic iron overload with more advanced lipid peroxidation, inflammation, and portal fibrosis than was observed with the disruption of either gene alone. The Hfe(-/-) ×Tfr2(mut) mouse model of iron-induced liver injury reflects the liver injury phenotype observed in human HH.

Overfeeding reduces insulin sensitivity and increases oxidative stress, without altering markers of mitochondrial content and function in humans

Background

Mitochondrial dysfunction and increased oxidative stress are associated with obesity and type 2 diabetes. High fat feeding induces insulin resistance and increases skeletal muscle oxidative stress in rodents, but there is controversy as to whether skeletal muscle mitochondrial biogenesis and function is altered.

Methodology and Principal Findings

Forty (37±2 y) non-obese (25.6±0.6 kg/m²) sedentary men (n = 20) and women (n = 20) were overfed (+1040±100 kcal/day, 46±1% of energy from fat) for 28 days. Hyperinsulinemic-euglycemic clamps were performed at baseline and day 28 of overfeeding and skeletal muscle biopsies taken at baseline, day 3 and day 28 of overfeeding in a sub cohort of 26 individuals (13 men and 13 women) that consented to having all 3 biopsies performed. Weight increased on average in the whole cohort by 0.6±0.1 and 2.7±0.3 kg at days 3 and 28, respectively (P<0.0001, without a significant difference in the response between men and women (P = 0.4). Glucose infusion rate during the hyperinsulinemic-euglycemic clamp decreased from 54.8±2.8 at baseline to 50.3±2.5 µmol/min/kg FFM at day 28 of overfeeding (P = 0.03) without a significant difference between men and women (P = 0.4). Skeletal muscle protein carbonyls and urinary F2-isoprostanes increased with overfeeding (P<0.05). Protein levels of muscle peroxisome proliferator-activated receptor gamma coactivator-1α (PGC1α) and subunits from complex I, II and V of the electron transport chain were increased at day 3 (all P<0.05) and returned to basal levels at day 28. No changes were detected in muscle citrate synthase activity or ex vivo CO₂ production at either time point.

Conclusions

Peripheral insulin resistance was induced by overfeeding, without reducing any of the markers of mitochondrial content that were examined. Oxidative stress was however increased, and may have contributed to the reduction in insulin sensitivity observed.

Trial Registration

ClinicalTrials.gov NCT00562393

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

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

Effect of iron chelation on myocardial infarct size and oxidative stress in ST-elevation-myocardial infarction

BACKGROUND

Experimental studies suggest that deferoxamine (DFO) limits the generation of reactive oxygen species by chelating redox-active iron and thereby may reduce ischemia-reperfusion injury and myocardial infarct (MI) size. We investigated whether DFO administered before reperfusion by primary percutaneous coronary intervention (PPCI) would ameliorate oxidative stress and MI size.

METHODS AND RESULTS

We randomly assigned 60 patients with ST-elevation-MI to receive an intravenous bolus of DFO (500 mg) immediately before PPCI followed by a 12-hour infusion (50 mg/kg of body weight) (n=28) or normal saline bolus and infusion (placebo group, n=32). MI size was measured by contrast-enhanced cardiac MRI (CMRI; day 3±1), creatine kinase and troponin I area-under-the-curve, and severity of wall motion abnormality on echocardiography. Clinical follow-up including repeat CMRI and echocardiography were performed at 3 months (100±17 days). Oxidative stress was assessed by plasma F(2)-isoprostane levels. DFO and placebo groups were well balanced with respect to baseline characteristics, symptom- and door-to-balloon times, pre-PPCI coronary patency, and infarct-related artery location. Serum iron levels were decreased with DFO treatment after PPCI compared with placebo (3.0±2.5 versus 12.6±5.5 μmol/L, P<0.0001), which persisted until the end of the infusion. In DFO-treated patients, there was a significant reduction in plasma F(2)-isoprostane levels immediately after PPCI (2878±1461 versus 2213±579 pmol/L, P=0.04). However, there was no difference in CMRI-determined infarct size (DFO, 17.4±10.8%, versus placebo, 18.6±10.2%; P=0.73), myocardial salvage index at 3 days or at 3 months, or the area-under-the-curve for creatine kinase or troponin I.

CONCLUSIONS

Adjunctive DFO treatment after the onset of ischemia and continued periprocedurally ameliorates oxidative stress without limiting infarct size.

CLINICAL TRIAL REGISTRATION

URL: http://www.anzctr.org.au/. Unique identifier: ACTRN12608000308392.

Nutritional intake and oxidative stress in chronic heart failure

BACKGROUND AND AIMS

Patients with chronic heart failure (CHF) are known to be at risk of malnutrition, and cardiac cachexia is an adverse prognostic indicator. The aim of this study was to determine the dietary adequacy of CHF patients compared with Dietary Reference Values, to compare the nutritional intake and status of CHF patients to a healthy comparison group, and finally to determine whether nutritional intake and status depended on New York Heart Association (NYHA) functional class.

METHODS AND RESULTS

Patients with CHF (n = 39) and a comparison group of 27 healthy participants, who did not have CHF, were asked to complete a four-day food diary, and energy and nutrient intakes were calculated. F(2α)-isoprostanes were measured in urine as an indicator of oxidative stress and antioxidants were measured in serum or plasma. Overall 73% of the CHF patients were consuming less than recommended energy intakes, and more than 50% of these patients were also consuming less than recommended vitamin D, selenium and zinc intakes. Nutrient intake (energy, vitamin B6, D, E, iron, folate and riboflavin) was lower in CHF patients than in the comparison group, with vitamin B6 and folate intake and antioxidant status decreasing, and isoprostane status increasing as NYHA functional class increased.

CONCLUSION

The majority of CHF patients do not meet dietary reference values for energy and a range of nutrients, and nutrient intake is lower in CHF patients than in healthy individuals. Dietary inadequacy tends to be increased in those with more severe disease.

Oxidative stress in surgery in an ageing population: pathophysiology and therapy

Reactive oxygen species (ROS) play an important role in the regulation of normal cellular function. When ROS are produced in excess they can have detrimental effects, a state known as oxidative stress. Thus ROS play both physiological and pathophysiological roles in the body. In clinical practice oxidative stress and its counterpart, antioxidant capacity can be measured and can guide remedial therapy. Oxidative stress can have a negative impact in all forms of major surgery including cardiac surgery, general surgery, trauma surgery, orthopedic surgery and plastic surgery; this is particularly marked in an ageing population. Many different therapies to reduce oxidative stress in surgery have been tried with variable results. We conclude that in surgical patients the assessment of oxidative stress, improvement of the understanding of its role, both positive and negative, and devising appropriate therapies represent fruitful fields for future research.

Reduced metal ion concentrations in atherosclerotic plaques from subjects with type 2 diabetes mellitus

AIMS

Transition metal ions have been implicated in atherosclerosis. The goal of this study was to investigate whether metal ion levels were higher in people with diabetes, in view of their increased risk of aggravated atherosclerosis.

METHODS AND RESULTS

Absolute concentrations of iron, copper, zinc and calcium, and products of protein and lipid oxidation were quantified in atherosclerotic lesions from subjects with (T2DM, n=27), without Type 2 diabetes (nonDM, n=22), or hyperglycaemia (HG, n=17). Iron (P<0.05), zinc (P<0.01) and calcium (P=0.01) were lower in T2DM compared to nonDM subjects. Copper levels were comparable. A strong correlation (r=0.618; P<0.001) between EPR-detectable and total iron in nonDM patients was not seen in T2DM. X-ray fluorescence microscopy revealed "hot spots" of iron in both T2DM and nonDM. Calcium and zinc co-localised and levels correlated strongly. F(2)-isoprostanes (P<0.05) and di-Tyr/Tyr ratio (P<0.025), oxidative damage markers were decreased in T2DM compared to nonDM, or HG.

CONCLUSION

Advanced atherosclerotic lesions from T2DM subjects unexpectedly contained lower levels of transition metal ions, and protein and lipid oxidation products, compared to nonDM and HG. These data do not support the hypothesis that elevated metal ion levels may be a major causative factor in the aggravated atherosclerosis observed in T2DM patients.

Application of medical and analytical methods in Lyme borreliosis monitoring

Lyme borreliosis (LB) is one of the most common tick-borne diseases in the northern hemisphere. It is a chronic inflammatory disease caused by the spirochaete Borrelia burgdorferi. In its early stages, pathological skin lesions, namely erythema chronicum migrans, appear. The lesions, usually localised at the site of the bite, may become visible from a few weeks up to 3 months after the infection. Predominant clinical symptoms of the disease also involve joint malfunctions and neurological or cardiac disorders. Lyme disease, in all its stages, may be successfully treated with antibiotics. The best results, however, are obtained in its early stages. In order to diagnose the disease, numerous medical or laboratory techniques have been developed. They are applied to confirm the presence of intact spirochaetes or spirochaete components such as DNA or proteins in tick vectors, reservoir hosts or patients. The methods used for the determination of LB biomarkers have also been reviewed. These biomarkers are formed during the lipid peroxidation process. The formation of peroxidation products generated by human organisms is directly associated with oxidative stress. Apart from aldehydes (malondialdehyde and 4-hydroxy-2-nonenal), many other unsaturated components such as isoprostenes and neuroprostane are obtained. The fast determination of these compounds in encephalic fluid, urine or plasma, especially in early stages of the disease, enables its treatment. Various analytical techniques which allow the determination of the aforementioned biomarkers have been reported. These include spectrophotometry as well as liquid and gas chromatography. The analytical procedure also requires the application of a derivatization step by the use of selected reagents.

The effects of immunosuppressants on vascular function, systemic oxidative stress and inflammation in rats

Immunosuppressants have been associated with increased cardiovascular disease risk. We determined the effects of calcineurin and mammalian target of rapamycin (mTOR) inhibitor administration on endothelial dysfunction and associated inflammation and oxidative stress in adult rats. Cyclosporine A (low and high dose), sirolimus, tacrolimus, everolimus and placebo were administered to 8-week-old male Wistar rats for 10 consecutive days. Aortic vascular endothelial and smooth muscle function were assessed ex vivo in organ baths. Maximal aortic contraction to noradrenaline in sirolimus-treated rats was significantly greater than cyclosporine groups, everolimus and placebo, whereas endothelial-dependent relaxation was significantly impaired with cyclosporine and tacrolimus compared with everolimus. Endothelial-independent relaxation was impaired in tacrolimus-treated rats compared with low dose cyclosporine, everolimus and sirolimus. Sirolimus was associated with a reduction in plasma interleukin (IL)-1β and tumour necrosis factor (TNF)-α and higher levels of catalase and total antioxidant status. In nontransplanted rats, vascular dysfunction was evident following administration of cyclosporine A, sirolimus and tacrolimus, whereas everolimus did not compromise aortic endothelial or smooth muscle function. At the doses administered in this model, the immunosuppressants exerted varying effects on vascular function.

Flavonoid-rich apples and nitrate-rich spinach augment nitric oxide status and improve endothelial function in healthy men and women: a randomized controlled trial

Flavonoids and nitrates in fruits and vegetables may protect against cardiovascular disease. Dietary flavonoids and nitrates can augment nitric oxide status via distinct pathways, which may improve endothelial function and lower blood pressure. Recent studies suggest that the combination of flavonoids and nitrates can enhance nitric oxide production in the stomach. Their combined effect in the circulation is unclear. Here, our objective was to investigate the independent and additive effects of flavonoid-rich apples and nitrate-rich spinach on nitric oxide status, endothelial function, and blood pressure. A randomized, controlled, crossover trial with healthy men and women (n=30) was conducted. The acute effects of four energy-matched treatments (control, apple, spinach, and apple+spinach), administered in random order, were compared. Measurements included plasma nitric oxide status, assessed by measuring S-nitrosothiols+other nitrosylated species (RXNO) and nitrite, blood pressure, and endothelial function, measured as flow-mediated dilatation of the brachial artery. Results are means and 95% CI. Relative to control, all treatments resulted in higher RXNO (control, 33 nmol/L, 26, 42; apple, 51 nmol/L, 40, 65; spinach, 86 nmol/L, 68, 110; apple+spinach, 69 nmol/L, 54, 88; P<0.01) and higher nitrite (control, 35 nmol/L, 27, 46; apple, 69 nmol/L, 53, 90; spinach, 99 nmol/L, 76, 129; apple+spinach, 80 nmol/L, 61, 104; P<0.01). Compared to control, all treatments resulted in higher flow-mediated dilatation (P<0.05) and lower pulse pressure (P<0.05), and apple and spinach resulted in lower systolic blood pressure (P<0.05). No significant effect was observed on diastolic blood pressure. The combination of apple and spinach did not result in additive effects on nitric oxide status, endothelial function, or blood pressure. In conclusion, flavonoid-rich apples and nitrate-rich spinach can independently augment nitric oxide status, enhance endothelial function, and lower blood pressure acutely, outcomes that may benefit cardiovascular health.

Association of clinical and aetiologic subtype of acute ischaemic stroke with inflammation, oxidative stress and vascular function: a cross-sectional observational study

Background

The role of inflammation, vascular dysfunction and oxidative stress in the pathophysiology of different stroke subtypes is not well understood. We aimed to determine if the clinical and aetiologic subtype of acute ischaemic stroke influences systemic markers of vascular function, inflammation and oxidative stress.

Material/Methods

129 men and women were recruited within 10 days of acute ischaemic stroke or TIA at two tertiary hospitals in this cross-sectional observational study. Stroke severity (NIHSS score and S100B concentration); systemic markers of inflammation (high sensitivity C-reactive protein [hs-CRP] and fibrinogen), endothelial activation (E-selectin), endothelial cell damage (von Willebrand factor activity), and oxidative stress (F₂-isoprostanes) were measured.

Results

Hs-CRP concentrations were higher in total anterior (22.0±24.1 mg/L) than partial anterior circulation (15.3±32.4 mg/L) and lacunar (4.9±4.3 mg/L) syndromes (p=0.01). Hs-CRP concentrations correlated moderately with NIHSS score (r=0.45, p<0.01) and S100B (r=0.48, p<0.01). However aetiologic and clinical subtypes were not independently associated with hs-CRP when included with stroke severity in general linear models.

Conclusions

These data suggest that stroke aetiology and clinical syndrome may not be important independent determinants of the degree of systemic inflammation, oxidative stress or endothelial function in acute ischaemic stroke. Other factors, including stroke severity, pre-morbid inflammation and co-morbidity may explain variations among groups of participants with different subtypes of acute ischaemic stroke.

Hemoglobin attenuates the effects of inspired oxygen on plasma isofurans in humans during upper-limb surgery

Reperfusion injury is characterized by significant oxidative stress. F(2)-isoprostanes (F(2)-IsoP's) and isofurans (IsoF's), the latter preferentially produced during increased oxygen tension, are recognized markers of in vivo oxidative stress. We aimed to determine whether increasing oxygen tension during reperfusion modified levels of plasma total IsoF's and F(2)-IsoP's. Forty-five patients undergoing upper-limb surgery were randomized to receive inspired oxygen concentrations of 30, 50, or 80% during the last 15 min of surgery. Venous blood samples were taken before the change in inspired oxygen, after 10 min (before reperfusion), and after 15 min (5 min after reperfusion). IsoF's and F(2)-IsoP's were measured by gas chromatography-mass spectrometry. Venous oxygen tension and hemoglobin concentrations were also measured. Plasma IsoF and F(2)-IsoP levels in the 50 and 80% O(2) groups were not significantly different from those of the 30% O(2) group. In secondary analyses, using data combining all groups, levels of IsoF's, but not F(2)-IsoP's, associated with higher venous oxygen tension (P=0.038). Hemoglobin negatively modified the influence of oxygen tension on levels of IsoF's (P=0.014). This study has shown, for the first time, that plasma IsoF levels associate with higher oxygen tension in a human model of reperfusion, and this effect is significantly attenuated by hemoglobin.

Effects of spinal or general anesthesia on F₂-isoprostanes and isofurans during ischemia/reperfusion of the leg in patients undergoing knee replacement surgery

General and spinal anesthesia are used extensively in orthopedic surgery. However, these methods of anesthesia may result in different amounts of oxygen being delivered to the patient. Ischemia/reperfusion injury after release of the tourniquet initiates free radical-mediated oxidative stress. F₂-isoprostanes are reliable markers of in vivo lipid peroxidation. However, under conditions of high oxygen tension, isofurans are formed. We aimed to compare plasma isofurans and F₂-isoprostanes in spinal versus general anesthesia in patients undergoing knee-replacement surgery in a randomized, blinded study. Thirty-nine patients were randomized to spinal (SA; n = 19) or general anesthesia (GA; n = 20). Blood was collected before anesthesia, and a tourniquet was then applied to the limb during surgery. After release of the tourniquet, blood samples were collected at 30 min, 2 h, and 24 h for measurement of plasma F₂-isoprostanes and isofurans by gas chromatography-mass spectrometry. The two groups were comparable in age and body mass index. Plasma F₂-isoprostanes were significantly lower in the GA patients compared with the SA patients (p = 0.045). In contrast, the GA patients had significantly elevated plasma isofurans (p = 0.032). Increased isofurans during GA compared with SA are likely to reflect increased oxidative stress due to elevated oxygen concentrations during GA. Further studies are required to assess the implications of these findings on perioperative outcomes.

Effects of a gliadin-combined plant superoxide dismutase extract on self-perceived fatigue in women aged 50-65 years

Fatigue syndromes exist on a continuum of severity from mild and transient to the disabling chronic fatigue syndrome, with oxidative stress linked to its pathogenesis. A thermolabile gliadin-combined plant superoxide dismutase (SOD) extract has shown potential in clinical trials as a therapeutic antioxidant. This study investigated the effects of 12 weeks of 500 mg/day of a SOD/gliadin supplement on fatigue. Thirty-eight women aged 50-65 years with self-perceived fatigue entered this randomized, double-blind, placebo-controlled trial. The primary outcome measure was general fatigue determined by the Multidimensional Fatigue Inventory (MFI). Secondary outcome measures included other measures of fatigue from the MFI and blood measures of oxidative stress, antioxidant status and hormones. There were no significant (P>0.05) differences between, or within groups, for decreases in general fatigue (active=1.6%, placebo=4.1%). There were no within or between group differences (P>0.05) in other measures of fatigue (physical fatigue, reduced activity, reduced motivation, mental fatigue and total fatigue score). In regard to the biochemical measures, there were non-significant (P>0.05) differences in increases in plasma SOD activity (active=7.1%, placebo=12.2%), plasma GPx activity (active=2.4%, placebo=0.7%), red blood cell GPx activity (active=9.8%, placebo=4.4%). Markers of oxidative stress were decreased but there were no differences (P>0.05) within or between groups; malondialdehyde (active=4.1%, placebo=1.6%), F-2 isoprostanes (active=14.7%, placebo=22.4%). There was a trend (P=0.08) for a decrease in cortisol in the active group (24.6%), however this was not significantly different from the decrease in the placebo participants (4.1%). DHEA differences were not significant (P<0.05) and declined 1.3% in the active group and 14.4% in the placebo group. In summary, the thermolabile SOD/gliadin supplement had no significant effect on self-perceived fatigue, antioxidants, oxidative stress or hormones in women aged 50-65 years.

The omega-3 fatty acids EPA and DHA decrease plasma F(2)-isoprostanes: Results from two placebo-controlled interventions

Omega-3 (omega3) fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), protect against cardiovascular disease. Despite these benefits, concern remains that omega3 fatty acids may increase lipid peroxidation. It has previously been shown that urinary F(2)-isoprostanes (F(2)-IsoPs) were reduced following omega3 fatty acid supplementation in humans. It is now determined whether EPA or DHA supplementation affects plasma F(2)-IsoPs. In two 6-week placebo-controlled interventions, Study A: overweight, dyslipidaemic men; and Study B: treated-hypertensive Type 2 diabetic, patients were randomized to 4 g daily EPA, DHA. Post-intervention plasma F(2)-IsoPs were significantly reduced by EPA (24% in Study A, 19% in Study B) and by DHA (14% in Study A, 23% in Study B) relative to the olive oil group. The fall in plasma F(2)-IsoPs was not altered in analyses that corrected for changes in plasma arachidonic acid, which was reduced with EPA and DHA supplementation. Neither F(3)- nor F(4)-IsoPs were observed in plasma in both studies. These results show that in humans, EPA and DHA reduce in vivo oxidant stress as measured in human plasma and urine.

An inter-laboratory validation of methods of lipid peroxidation measurement in UVA-treated human plasma samples

Lipid peroxidation products like malondialdehyde, 4-hydroxynonenal and F(2)-isoprostanes are widely used as markers of oxidative stress in vitro and in vivo. This study reports the results of a multi-laboratory validation study by COST Action B35 to assess inter-laboratory and intra-laboratory variation in the measurement of lipid peroxidation. Human plasma samples were exposed to UVA irradiation at different doses (0, 15 J, 20 J), encoded and shipped to 15 laboratories, where analyses of malondialdehyde, 4-hydroxynonenal and isoprostanes were conducted. The results demonstrate a low within-day-variation and a good correlation of results observed on two different days. However, high coefficients of variation were observed between the laboratories. Malondialdehyde determined by HPLC was found to be the most sensitive and reproducible lipid peroxidation product in plasma upon UVA treatment. It is concluded that measurement of malondialdehyde by HPLC has good analytical validity for inter-laboratory studies on lipid peroxidation in human EDTA-plasma samples, although it is acknowledged that this may not translate to biological validity.

Advances in methods for the determination of biologically relevant lipid peroxidation products

Lipid peroxidation is recognized to be an important contributor to many chronic diseases, especially those of an inflammatory pathology. In addition to their value as markers of oxidative damage, lipid peroxidation products have also been shown to have a wide variety of biological and cell signalling effects. In view of this, accurate and sensitive methods for the measurement of lipid peroxidation products are essential. Although some assays have been described for many years, improvements in protocols are continually being reported and, with recent advances in instrumentation and technology, highly specialized and informative techniques are increasingly used. This article gives an overview of the most currently used methods and then addresses the recent advances in some specific approaches. The focus is on analysis of oxysterols, F(2)-isoprostanes and oxidized phospholipids by gas chromatography or liquid chromatography mass spectrometry techniques and immunoassays for the detection of 4-hydroxynonenal.

The effects of a lupin-enriched diet on oxidative stress and factors influencing vascular function in overweight subjects

A diet enriched in lupin kernel flour can lower blood pressure, but mechanisms responsible are unclear. Lupin is a source of polyphenols, protein, and L-arginine, factors that may influence blood pressure via effects on oxidative stress and vascular function. Therefore, we aimed to determine the effects of a lupin-enriched diet on oxidative stress and factors influencing vascular function as potential mechanisms for demonstrated benefits on blood pressure. Overweight men and women (n = 88) were recruited to a 16-week parallel-design study. Participants were randomly assigned to replace 15%-20% of their usual daily energy intake with white bread (control) or lupin kernel flour-enriched bread (lupin). All measurements were taken at baseline and 16 weeks. At baseline, plasma F₂-isoprostanes and 20-hydroxyeicosatetraenoic acid (20-HETE) were positively associated with blood pressure, and plasma nitrite was negatively associated with blood pressure (p < 0.05). For lupin relative to control, the estimated differences in plasma F₂-isoprostanes (45 pmol/L; 95%CI: -68, 158), urinary F₂-isoprostanes (17 pmol/mmol creatinine; 95%CI: -43, 76), plasma 20-HETE (75 pmol/L; 95%CI: -91, 241), and plasma nitrite (-0.3 μmol/L; 95%CI: -1.1, 0.4) were not significant. Although regular consumption of lupin-enriched bread can lower blood pressure, these results do not support for the hypothesis that this is via effects on oxidative stress or vascular function.

Systemic markers of inflammation are independently associated with S100B concentration: results of an observational study in subjects with acute ischaemic stroke

Background

Vascular dysfunction and brain inflammation are thought to contribute to the pathophysiology of cerebral injury in acute stroke. However acute inflammation and vascular dysfunction may simply be markers of an acute phase response to cerebral injury, reflecting the size of the cerebral lesion. We aimed to determine if systemic markers of vascular dysfunction and inflammation are independently associated with concentrations of the astroglial protein S100B, a marker of brain injury, in participants with acute ischaemic stroke.

Methods

Fifty-seven men and women recruited within 96 hours of acute ischaemic stroke at two tertiary hospitals participated in this cross sectional observational study. Clinical, imaging (stroke lesions area measured with perfusion CT) and laboratory data were the independent variables and co-variates. The outcome variable was serum S100B concentration, analysed by multivariate regression.

Results

High sensitivity-CRP (B = 0.41) and lesion area (B = 0.69) were independently associated with S100B concentration (R² = 0.75, p < 0.01). Other variables with significant univariate associations with S100B concentration were not independently associated with S100B concentration in the final multivariate model.

Conclusion

The degree of systemic inflammation is associated with S100B concentration in acute ischaemic stroke, independent of the size of the ischaemic lesion.

Isoprostanes and phytoprostanes: Bioactive lipids

Polyunsaturated fatty acids (PUFA) are important constituents in all eukaryotic organisms, contributing to the structural integrity of biological membranes and serving as precursors for enzymatically-generated local hormones. In addition to these functions, PUFA can generate by a free radical-initiated mechanism, key products which participate in a variety of pathophysiological processes. In particular, free radical-catalyzed peroxidation of PUFA leads to in vivo formation of isoprostanes (IsoP), neuroprostanes (NeuroP), and phytoprostanes (PhytoP) which display a wide range of biological actions. IsoP are now the most reliable indicators of oxidative stress in humans. In this review, we will discuss some advances in our knowledge regarding two cyclic PUFA derivatives, IsoP and PhytoP, and how their biological roles may be clarified through new approaches based on analytical and synthetic organic chemistry.

Effects of sepiapterin supplementation and NOS inhibition on glucocorticoid-induced hypertension

BACKGROUND

Glucocorticoid-induced hypertension is associated with imbalance between nitric oxide (NO) and superoxide. One of the pathways that causes this imbalance is endothelial NO synthase (eNOS) uncoupling. In the present study, adrenocorticotrophic hormone (ACTH)- and dexamethasone-treated rats were further treated with sepiapterin, a precursor of tetrahydrobiopterin, or N-nitro-L-arginine (NOLA), an inhibitor of NOS, to investigate the role of eNOS uncoupling in glucocorticoid-induced hypertension.

METHODS

Male Sprague-Dawley (SD) rats (n = 7-13/group) were treated with either sepiapterin (5 mg/kg/day, IP) or saline (sham) 4 days before and during ACTH (0.2 mg/kg/day, SC), dexamethasone (0.03 mg/kg/day, SC), or saline treatment. NOLA (0.4 mg/ml in drinking water) was given to rats 4 days before and during dexamethasone treatment. Systolic blood pressure (SBP) was measured by the tail-cuff method.

RESULTS

Both ACTH (116 +/- 2 to 135 +/- 3 mm Hg (mean +/- s.e.m.), P < 0.001) and dexamethasone (114 +/- 4 to 133 +/- 3 mm Hg, P < 0.0005) increased SBP. Sepiapterin alone did not alter SBP. Sepiapterin did not prevent ACTH- (129 +/- 4 mm Hg, NS) or dexamethasone-induced hypertension (135 +/- 3 mm Hg, NS), although plasma total biopterin concentrations were increased. NOLA increased SBP in rats prior to dexamethasone or saline treatment. NOLA further increased SBP in both saline- (133 +/- 4 to 157 +/- 3 mm Hg, P < 0.05) and dexamethasone-treated rats (135 +/- 5 to 170 +/- 6 mm Hg, P < 0.05). ACTH and dexamethasone increased plasma F(2)-isoprostane concentrations. Neither sepiapterin nor NOLA significantly affected this marker of oxidative stress.

CONCLUSION

Sepiapterin did not prevent ACTH- or dexamethasone-induced hypertension. NOLA exacerbated dexamethasone-induced hypertension. These data suggest that eNOS uncoupling does not play a major role in the genesis of glucocorticoid-induced hypertension in the rat.

Antioxidant defenses in the rat placenta in late gestation: increased labyrinthine expression of superoxide dismutases, glutathione peroxidase 3, and uncoupling protein 2

Placental oxidative stress plays a key role in the pathophysiology of placenta-related disorders, most notably preeclampsia (PE) and intrauterine growth restriction (IUGR). Oxidative stress occurs when accumulation of reactive oxygen species (ROS) damages DNA, proteins and lipids, an outcome that is limited by antioxidant enzymes; mitochondrial uncoupling protein 2 (UCP2) may also limit oxidative stress by reducing ROS production. Here we characterized placental antioxidant defenses during normal gestation and following glucocorticoid-induced IUGR. Placentas were collected on Days 16 and 22 of normal rat pregnancy (term = Day 23) and at Day 22 after dexamethasone treatment from Day 13. Expression of several genes encoding antioxidant enzymes (Sod1, Sod2, Sod3, Cat, Gpx3, Txn1, Txnrd1, Txnrd2, and Txnrd3) and Ucp2 was measured by quantitative RT-PCR in the labyrinth (LZ) and junctional zones (JZ) of the placenta. Expression of Sod1 and Ucp2 mRNAs and the activity of xanthine oxidase, a source of ROS, all increased from Days 16 to 22 in both placental zones, whereas Sod2 and Gpx3 increased only in the rapidly growing LZ. In contrast, Sod3 and Txnrd1 expression fell in the LZ over this period, whereas total superoxide dismutase activity remained stable. Dexamethasone treatment reduced fetal-placental growth and LZ expression of Ucp2 but increased JZ expression of Txn1. Indices of placental oxidative damage (TBARS, F(2)-isoprostanes, and 8-OHdG) did not change with gestational age or dexamethasone, indicative of adequate antioxidant protection. Overall, our data suggest that the rat placenta is protected from oxidative stress by the dynamic zone- and stage-dependent expression of antioxidant defense genes.

Specific Dietary Polyphenols Attenuate Atherosclerosis in Apolipoprotein E–Knockout Mice by Alleviating Inflammation and Endothelial Dysfunction

Objective— Animal and clinical studies have suggested that polyphenols in fruits, red wine, and tea may delay the development of atherosclerosis through their antioxidant and anti-inflammatory properties. We investigated whether individual dietary polyphenols representing different polyphenolic classes, namely quercetin (flavonol), (−)-epicatechin (flavan-3-ol), theaflavin (dimeric catechin), sesamin (lignan), or chlorogenic acid (phenolic acid), reduce atherosclerotic lesion formation in the apolipoprotein E (ApoE) −/− gene–knockout mouse.

Methods and Results— Quercetin and theaflavin (64-mg/kg body mass daily) significantly attenuated atherosclerotic lesion size in the aortic sinus and thoracic aorta ( P <0.05 versus ApoE −/− control mice). Quercetin significantly reduced aortic F 2 -isoprostane, vascular superoxide, vascular leukotriene B 4 , and plasma-sP-selectin concentrations; and augmented vascular endothelial NO synthase activity, heme oxygenase-1 protein, and urinary nitrate excretion ( P <0.05 versus control ApoE −/− mice). Theaflavin showed similar, although less extensive, significant effects. Although (−)-epicatechin significantly reduced F 2 -isoprostane, superoxide, and endothelin-1 production ( P <0.05 versus control ApoE −/− mice), it had no significant effect on lesion size. Sesamin and chlorogenic acid treatments exerted no significant effects. Quercetin, but not (−)-epicatechin, significantly increased the expression of heme oxygenase-1 protein in lesions versus ApoE −/− controls.

Conclusion— Specific dietary polyphenols, in particular quercetin and theaflavin, may attenuate atherosclerosis in ApoE −/− gene–knockout mice by alleviating inflammation, improving NO bioavailability, and inducing heme oxygenase-1. These data suggest that the cardiovascular protection associated with diets rich in fruits, vegetables, and some beverages may in part be the result of flavonoids, such as quercetin.

Parenteral lipid emulsions based on olive oil compared with soybean oil in preterm (<28 weeks' gestation) neonates: a randomised controlled trial

BACKGROUND

: New olive oil-based (OL) lipid emulsions (olive:soy oil = 4:1) have lower polyunsaturated fatty acid (PUFA) (20% vs 60%) and higher vitamin E content (an antioxidant) compared with traditional soybean oil (SO) emulsions.

OBJECTIVE

: Compare efficacy and safety of OL with SO emulsions in preterm neonates (<28 weeks) at high risk for oxidative stress.

PATIENTS AND METHODS

: Preterm neonates (gestation 23-<28 weeks) were randomised to receive OL or SO emulsion for 5 days using a standard protocol in a tertiary perinatal centre (King Edward Memorial Hospital for Women, Perth, Western Australia). Investigators and outcome assessors were masked to allocation. Plasma F2-isoprostanes (lipid peroxidation marker), plasma, and red blood cell fatty acids were measured before and after the study. Safety was monitored by liver function tests.

RESULTS

: Forty-four of 50 participants (OL-23, SO-21) completed the study. Both emulsions were well tolerated with no significant adverse events. F2-isoprostane levels were comparable at baseline and study end. Oleic and linoleic acid levels were significantly high on day 6 in OL and SO groups, respectively. Long-chain PUFA levels were similar between groups despite the lower PUFA content of OL. The olive oil-based group had significantly higher levels of C18:4n-3, suggesting Delta6-desaturase enzyme inhibition in the SO group.

CONCLUSIONS

: Olive oil-based emulsion was safe and well tolerated by preterm neonates. Similar long-chain PUFA levels were achieved in the OL group despite significantly lower amount of PUFA content; however, there was no difference in lipid peroxidation (F2-isoprostane levels). Large trials are needed to confirm these benefits.

Time course and dose response of alpha tocopherol on oxidative stress in haemodialysis patients

Background

Oxidative stress is associated with increased cardiovascular morbidity and mortality particularly in patients with end stage kidney disease. Although observational data from the general population has shown dietary antioxidant intake is associated with reduced cardiovascular morbidity and mortality, most clinical intervention trials have failed to support this relationship. This may be a consequence of not using an effective antioxidant dose and/or not investigating patients with elevated oxidative stress. The SPACE study, conducted in haemodialysis patients, reported that 800 IU/day of alpha tocopherol significantly reduced cardiovascular disease endpoints. A recent time course and dose response study conducted in hypercholesterolaemic patients that found 1600 IU/day of alpha tocopherol was an optimal dose. There is no such dose response data available for haemodialysis patients. Therefore the aim of this study is to investigate the effect of different doses of oral alpha tocopherol on oxidative stress in haemodialysis patients with elevated oxidative stress and the time taken to achieve this effect.

Methods

The study will consist of a time-course followed by a dose response study. In the time course study 20 haemodialysis patients with elevated oxidative stress will take either 1600 IU/day natural (RRR) alpha tocopherol for 20 weeks or placebo. Blood will be collected every two weeks and analysed for a marker of oxidative stress (plasma F₂-isoprostanes) and alpha tocopherol. The optimum time period to significantly decrease plasma F₂-isoprostanes will be determined from this study. In the dose response study 60 patients will be randomised to receive either placebo, 100, 200, 400, 800 or 1600 IU/day of natural (RRR) alpha tocopherol for a time period determined from the time course study. Blood will be collected at baseline and every two weeks and analysed for plasma F₂-isoprostanes and alpha tocopherol. It is hypothesised that doses ≥ 800 IU of vitamin E will be required to significantly decrease plasma F₂-isoprostanes.

Discussion

This study will determine the time and dose required for alpha tocopherol to significantly decrease oxidative stress in haemodialysis patients. Data will be used to plan a large randomised controlled trial to assess the effects of alpha tocopherol on cardiovascular outcomes in haemodialysis patients.

Trial Registration

ACTRN12609000608268

Quantification of F2-isoprostanes as a reliable index of oxidative stress in vivo using gas chromatography-mass spectrometry (GC-MS) method

Free radical-induced lipid peroxidation has been implicated in a number of human diseases including atherosclerosis, cancer, and neurodegenerative diseases. F(2)-Isoprostanes (IsoPs) are isomers of prostaglandin PGF(2alpha) that are generated in vivo from the free radical-initiated peroxidation of arachidonic acid independent of cyclooxygenase enzymes. Since the discovery of the IsoPs in the early 1990s, a large body of evidence has been accumulated to indicate that quantification of these F(2)-IsoPs represents the most reliable biomarker to assess oxidative stress in vivo. A variety of analytical approaches have been developed for the quantification of these novel compounds; these methods include mass spectrometry (MS) detection coupled to gas chromatography (GC) or liquid chromatography (LC) separation, and detection using immunological approaches. This article summarizes our current methodology to quantify F(2)-IsoPs in biological fluids and tissues using GC-MS. This method includes solid-phase extraction (SPE), thin-layer chromatography (TLC) purification, chemical derivatization, and MS detection using negative ion chemical ionization (NICI) coupled with GC. The protocol described herein has been optimized and validated to provide the best sensitivity and selectivity for quantification of F(2)-IsoPs from a variety of biological sources.

Fish Oil Supplementation in Pregnancy Lowers F2-isoprostanes in Neonates at High Risk of Atopy

The anti-inflammatory properties of n-3 polyunsaturated fatty acids (n-3 PUFA) have suggested a potential role of these nutrients in dietary modification for prevention of allergic disease in early life. As oxidative stress is known to modify antigen presenting cell (APC) signalling and resulting immune responses, we examined the effects of maternal n-3 PUFA supplementation in pregnancy on markers of oxidative stress and APC function in neonates at high risk of allergy. Eighty-three pregnant atopic women were randomised to receive 4 g daily of either fish oil (n = 40) or olive oil (n = 43) capsules in a controlled trial from 20 weeks gestation until delivery. Plasma (cord blood) and urinary F2-isoprostanes were measured as markers of lipid peroxidation. Cord erythrocyte fatty acids and markers of APC function (HLA-DR expression and cytokine responses) were measured and related to levels of plasma F2-isoprostanes. Maternal fish oil supplementation lowered plasma (p < 0.0001) and urinary (p = 0.06) F2-isoprostanes. HLA-DR expression on APC was not different between the groups. In multiple regression analysis, 28.8% of the variance in plasma F2-isoprostanes was explained by positive relationships with erythrocyte arachidonic acid (AA) and monocyte HLA-DR expression and a negative relationship with erythrocyte eicosapentaenoic acid (EPA). This study shows that maternal supplementation with fish oil can attenuate neonatal lipid peroxidation. Clinical follow-up of these infants will help to determine if there are sustained effects on postnatal oxidative stress and expression of allergic disease.

Increased consumption of wheat biofortified with selenium does not modify biomarkers of cancer risk, oxidative stress, or immune function in healthy Australian males

Increased intake of selenium (Se) may reduce the risk of degenerative diseases including cancer but excessive intake may be toxic. Wheat is a major source of dietary Se in humans. However, the effect of Se from wheat that is agronomically biofortified with Se on biomarkers of human health status is unknown. This study aimed to investigate whether improving Se status, by increased dietary intake of Se-biofortified wheat, affects biomarkers of cancer risk, cardiovascular disease risk, oxidative stress, and immune function in healthy South Australian men. A 24-week placebo-controlled double-blind intervention was performed in healthy older men (n = 62), with increased dose of Se intake every 8 weeks. Wheat was provided as 1, 2, and 3 puffed wheat biscuits, during weeks 1-8, 9-16, and 17-24, respectively. Blood was collected to measure a wide range of disease risk biomarkers. Consumption of Se-biofortified wheat was found to increase plasma Se concentration from a baseline level of 122 to 192 microg/L following intake of three biscuits/day, which provided 267 microg Se. Platelet glutathione peroxidase, chromosome aberrations, and DNA damage in lymphocytes measured using the cytokinesis-block micronucleus cytome assay and with the Comet assay, plasma F2-isoprostanes, protein carbonyls, plasma C-reactive protein, and leukocyte number were unaffected by the improved Se status. Improvement of Se status by consumption of Se-biofortified wheat did not substantially modify the selected biomarkers of degenerative disease risk and health status in this apparently selenium-replete cohort of healthy older men in South Australia.

Assessment of arterial stiffness, oxidative stress and inflammation in acute kidney injury

BACKGROUND

It is well know that arterial stiffness, oxidative stress and inflammation are features of chronic kidney disease. The arterial changes have a multitude of potential interconnected causes including endothelial dysfunction, oxidative stress, inflammation, atherosclerosis and vascular calcification. There is evidence that arterial stiffness becomes progressively worse as CKD progresses. The contribution of the biochemical changes of uremic toxicity to arterial stiffness is less clear. The aim of this study is to elucidate the vascular changes in acute kidney injury. We hypothesise that arterial stiffness will be increased during acute kidney injury and this will return to normal after kidney function recovers.

METHODS/DESIGN

One hundred and forty four patients with acute kidney injury defined as an acute increase in serum creatinine to > 133 micromol/l or urea > 14.3 mmol/l or urine output < 410 ml/day will be recruited. Baseline measures of aortic pulse wave velocity, augmentation index, and brachial and central blood pressure will be recorded along with blood measures for oxidative stress and inflammation. Repeat measures will be taken at six and 12 months after the onset of the acute kidney injury.

DISCUSSION

The role and contribution of the biochemical changes to arterial stiffness in the acute phase of kidney disease is not known. This study will primarily assess the time course changes in pulse wave velocity from the onset of acute kidney injury and after recovery. In addition it will assess augmentation index, central blood pressure and oxidative stress and inflammation. This may shed light on the contribution of biochemical kidney toxins on arterial stiffness in both acute kidney injury and chronic kidney disease.

TRIAL REGISTRATION

ACTRN 12609000285257.

Taurine supplementation increases skeletal muscle force production and protects muscle function during and after high-frequency in vitro stimulation

Recent studies report that depletion and repletion of muscle taurine (Tau) to endogenous levels affects skeletal muscle contractility in vitro. In this study, muscle Tau content was raised above endogenous levels by supplementing male Sprague-Dawley rats with 2.5% (wt/vol) Tau in drinking water for 2 wk, after which extensor digitorum longus (EDL) muscles were examined for in vitro contractile properties, fatigue resistance, and recovery from fatigue after two different high-frequency stimulation bouts. Tau supplementation increased muscle Tau content by approximately 40% and isometric twitch force by 19%, shifted the force-frequency relationship upward and to the left, increased specific force by 4.2%, and increased muscle calsequestrin protein content by 49%. Force at the end of a 10-s (100 Hz) continuous tetanic stimulation was 6% greater than controls, while force at the end of the 3-min intermittent high-frequency stimulation bout was significantly higher than controls, with a 12% greater area under the force curve. For 1 h after the 10-s continuous stimulation, tetanic force in Tau-supplemented muscles remained relatively stable while control muscle force gradually deteriorated. After the 3-min intermittent bout, tetanic force continued to slowly recover over the next 1 h, while control muscle force again began to decline. Tau supplementation attenuated F(2)-isoprostane production (a sensitive indicator of reactive oxygen species-induced lipid peroxidation) during the 3-min intermittent stimulation bout. Finally, Tau transporter protein expression was not altered by the Tau supplementation. Our results demonstrate that raising Tau content above endogenous levels increases twitch and subtetanic and specific force in rat fast-twitch skeletal muscle. Also, we demonstrate that raising Tau protects muscle function during high-frequency in vitro stimulation and the ensuing recovery period and helps reduce oxidative stress during prolonged stimulation.

Coenzyme Q10 improves endothelial dysfunction in statin-treated type 2 diabetic patients

OBJECTIVE

The vascular benefits of statins might be attenuated by inhibition of coenzyme Q(10) (CoQ(10)) synthesis. We investigated whether oral CoQ(10) supplementation improves endothelial dysfunction in statin-treated type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

In a double-blind crossover study, 23 statin-treated type 2 diabetic patients with LDL cholesterol <2.5 mmol/l and endothelial dysfunction (brachial artery flow-mediated dilatation [FMD] <5.5%) were randomized to oral CoQ(10) (200 mg/day) or placebo for 12 weeks. We measured brachial artery FMD and nitrate-mediated dilatation (NMD) by ultrasonography. Plasma F(2)-isoprostane and 24-h urinary 20-hydroxyeicosatetraenoic acid (HETE) levels were measured as systemic oxidative stress markers.

RESULTS

Compared with placebo, CoQ(10) supplementation increased brachial artery FMD by 1.0 +/- 0.5% (P = 0.04), but did not alter NMD (P = 0.66). CoQ(10) supplementation also did not alter plasma F(2)-isoprostane (P = 0.58) or urinary 20-HETE levels (P = 0.28).

CONCLUSIONS

CoQ(10) supplementation improved endothelial dysfunction in statin-treated type 2 diabetic patients, possibly by altering local vascular oxidative stress.

Plasma IL-6, its soluble receptors and F2-isoprostanes at rest and during exercise in chronic fatigue syndrome

The aim of the current study was to investigate the levels of interleukin-6 (IL-6), its soluble receptors (sIL-6R and sgp130) and F(2)-isoprostanes, at rest and during exercise, in patients with chronic fatigue syndrome (CFS). Six male CFS patients and six healthy controls performed an incremental exercise test to exhaustion and a submaximal exercise bout to exhaustion. Blood samples taken in the submaximal test at rest, immediately post-exercise and 24 h post-exercise were analyzed for IL-6, sIL-6R, sgp130 and F(2)-isoprostanes. A further 33 CFS and 33 healthy control participants gave a resting blood sample for IL-6 and sIL-6R measurement. During the incremental exercise test only power output at the lactate threshold was lower (P<0.05) in the CFS group. F(2)-isoprostanes were higher (P<0.05) in CFS patients at rest and this difference persisted immediately and 24 h post-exercise. The exercise study found no differences in IL-6, sIL-6R or sgp130 at any time point between groups. In the larger resting group, there were no differences in IL-6 and sIL-6R between CFS and control groups. This investigation has demonstrated that patients with CFS do not have altered plasma levels of IL-6, sIL-6R or sgp130 either at rest or following exercise. F(2)-isoprostanes, however, were consistently higher in CFS patients.

Comparison of markers of oxidative stress, inflammation and arterial stiffness between incident hemodialysis and peritoneal dialysis patients--an observational study

BACKGROUND

Patients on peritoneal and hemodialysis have accelerated atherosclerosis associated with an increase in cardiovascular morbidity and mortality. The atherosclerosis is associated with increased arterial stiffness, endothelial dysfunction and elevated oxidative stress and inflammation. The aims of this study are to investigate the effects of peritoneal and hemodialysis on arterial stiffness, vascular function, myocardial structure and function, oxidative stress and inflammation in incident patients with end stage kidney disease.

METHODS

This is an observational study. Eighty stage five CKD patients will be enrolled and followed for one-year. Primary outcome measures will be changes in 1) arterial stiffness measured by aortic pulse wave velocity, 2) oxidative stress assessed by plasma F2 isoprostanes and 3) inflammation measured by plasma pentraxin-3. Secondary outcomes will include additional measures of oxidative stress and inflammation, changes in vascular function assessed using the brachial artery reactivity technique, carotid artery intimal medial thickness, augmentation index and trans thoracic echocardiography to assess left ventricular geometry, and systolic and diastolic function. Patients will undergo these measures at baseline (6-8 weeks prior to starting dialysis therapy), then at six and 12 months after starting dialysis.

DISCUSSION

The results of this study may guide the choice of dialysis modality in the first year of treatment. It may also lead to a larger study prospectively assessing the effect of dialysis modality on cardiovascular morbidity and mortality.

TRIAL REGISTRATION

ACTRN12609000049279.

Different patterns of oxidized lipid products in plasma and urine of dengue fever, stroke, and Parkinson's disease patients: cautions in the use of biomarkers of oxidative stress

Many products of lipid oxidation have been associated with human diseases. These include F2-isoprostanes (F2-IsoPs), hydroxyeicosatetraenoic acid products (HETEs), and cholesterol oxidation products (COPs). Here we present measurements of F2-IsoPs, HETEs, COPs, and arachidonate in single plasma samples of patients with acute (dengue fever and ischemic stroke) and chronic (Parkinson's) diseases, and in age-matched study controls. Urine samples were collected for F2-IsoPs analysis. Our analysis demonstrated elevated F2-IsoPs levels in ischemic stroke, HETEs in Parkinson's disease, dengue fever, and ischemic stroke, and COPs in Parkinson's disease and dengue fever patients, as compared with those in age-matched study controls. Strong but complex correlations were observed between levels of certain oxidized lipid products and age. The relations between various oxidized lipids and dengue fever, stroke, and Parkinson's disease are discussed in relation to the selection and application of biomarkers of oxidative lipid damage, in particular the need for corrections for age and lipid levels.

20-HETE and F2-isoprostanes in the metabolic syndrome: the effect of weight reduction

20-Hydroxyeicosatetraenoic acid (20-HETE) is a cytochrome P450 metabolite of arachidonic acid that regulates vascular function and sodium homeostasis. Studies showing an association between 20-HETE excretion, raised BMI, and oxidative stress suggest that 20-HETE may be important in the development of cardiovascular disease in the metabolic syndrome (MetS). We investigated whether 20-HETE and F(2)-isoprostanes (markers of oxidative stress) were altered in the MetS before and after weight reduction. A case-controlled comparison of 30 participants with the MetS and matched controls showed that plasma and urinary 20-HETE and F(2)-isoprostanes were significantly elevated in the MetS group. There was a significant gender x group interaction such that women with the MetS had higher urinary 20-HETE and F(2)-isoprostanes compared to controls (p<0.0001). In a randomized controlled trial, 42 participants with the MetS were assigned to 16 weeks of weight maintenance or a 12-week weight-loss program followed by 4 weeks weight stabilization. Relative to the weight-maintenance group, a 4-kg loss in weight resulted in a 2-mm Hg fall in blood pressure (BP) but did not alter urinary or plasma 20-HETE or F(2)-isoprostanes. 20-HETE and oxidative stress may be important mediators of cardiovascular disease risk in the MetS. Although a 4% reduction in body weight reduced BP, there were no changes in plasma or urinary 20-HETE or F(2)-isoprostanes.

Astaxanthin vs placebo on arterial stiffness, oxidative stress and inflammation in renal transplant patients (Xanthin): a randomised controlled trial

Background

There is evidence that renal transplant recipients have accelerated atherosclerosis manifest by increased cardiovascular morbidity and mortality. The high incidence of atherosclerosis is, in part, related to increased arterial stiffness, vascular dysfunction, elevated oxidative stress and inflammation associated with immunosuppressive therapy. The dietary supplement astaxanthin has shown promise as an antioxidant and anti-inflammatory therapeutic agent in cardiovascular disease. The aim of this trial is to investigate the effects of astaxanthin supplementation on arterial stiffness, oxidative stress and inflammation in renal transplant patients.

Method and Design

This is a randomised, placebo controlled clinical trial. A total of 66 renal transplant recipients will be enrolled and allocated to receive either 12 mg/day of astaxanthin or an identical placebo for one-year. Patients will be stratified into four groups according to the type of immunosuppressant therapy they receive: 1) cyclosporine, 2) sirolimus, 3) tacrolimus or 4) prednisolone+/-azathioprine, mycophenolate mofetil or mycophenolate sodium. Primary outcome measures will be changes in 1) arterial stiffness measured by aortic pulse wave velocity (PWV), 2) oxidative stress assessed by plasma isoprostanes and 3) inflammation by plasma pentraxin 3. Secondary outcomes will include changes in vascular function assessed using the brachial artery reactivity (BAR) technique, carotid artery intimal medial thickness (CIMT), augmentation index (AIx), left ventricular afterload and additional measures of oxidative stress and inflammation. Patients will undergo these measures at baseline, six and 12 months.

Discussion

The results of this study will help determine the efficacy of astaxanthin on vascular structure, oxidative stress and inflammation in renal transplant patients. This may lead to a larger intervention trial assessing cardiovascular morbidity and mortality.

Trial Registration

ACTRN12608000159358

HDL is the major lipoprotein carrier of plasma F2-isoprostanes

Enhanced oxidative stress is implicated in the development of atherosclerosis in humans and animal models. F(2)-isoprostanes are formed in vivo via free radical peroxidation of arachidonic acid, and their quantification has allowed assessment of oxidative stress in vivo. F(2)-isoprostanes associate with lipids, although their distribution in human plasma lipoproteins is unknown. Our aim was to determine the distribution and levels of F(2)-isoprostanes in lipoproteins isolated from human plasma by ultracentrifugation and fast protein liquid chromatography (FPLC). F(2)-isoprostanes were significantly higher in HDL compared with LDL or VLDL after isolation by ultracentrifugation or FPLC. Furthermore, HDL3 particles contained elevated levels of F(2)-isoprostanes compared with HDL2. Platelet activating factor acetylhydrolase (PAF-AH), which hydrolyses esterified F(2)-isoprostanes from phospholipids, was predominantly associated with LDL. Reduced F(2)-isoprostanes in LDL may be related to higher PAF-AH activity in LDL. Paraoxonase 1 (PON-1) activity was associated with HDL2 and may be a contributing factor to the lower F(2)-isoprostanes in HDL2 compared with HDL3. Further studies are required to establish the implications of these findings on HDL function.

Association between both lipid and protein oxidation and the risk of fatal or non-fatal coronary heart disease in a human population

The role of oxidative damage in the aetiology of coronary disease remains controversial, as clinical trials investigating the effect of antioxidants have not generally been positive. In the present study, 227 coronary cases, identified from a cohort study, were matched, by age and gender, with 420 controls in a nested case-control design. Stored plasma samples were analysed for F2-isoprostanes by stable isotope dilution MS, and specifically oxidized forms of apoA-I (apolipoprotein A-I) by HPLC of HDL (high-density lipoprotein). Median values of F2-isoprostanes were higher in plasma samples that contained oxidized apoA-I compared with samples with undetectable oxidized apoA-I (1542 compared with 1165 pmol/l). F2-Isoprostanes were significantly correlated with variants of non-oxidized apoA-II (r=−0.15) and were associated with HDL-cholesterol (P<0.0001). F2-Isoprostanes in cases (median, 1146 pmol/l) were not different from controls (1250 pmol/l); the odds ratio (95% confidence interval) for a 1 S.D. increase in F2-isoprostanes was 1.08 (0.91–1.29). Similarly, there was no independent association between the presence of oxidized apoA-I, detected in approx. 20% of the samples, and coronary risk. In conclusion, we found no evidence of associations between markers of lipid (F2-isoprostanes) and protein (oxidized apoA-I) oxidation and the risk of fatal or non-fatal coronary heart disease in a general population. This may be due to a true lack of association or insufficient power.