Redox-dependent thiol modifications: implications for the release of extracellular vesicles.

Extracellular vesicles (EVs), including microvesicles and exosomes, are emerging as important regulators of homeostasis and pathophysiology. During pro-inflammatory and pro-oxidant conditions, EV release is induced. As EVs released under such conditions often exert pro-inflammatory and procoagulant effects, they may actively promote the pathogenesis of chronic diseases. There is evidence that thiol group-containing antioxidants can prevent EV induction by pro-inflammatory and oxidative stimuli, likely by protecting protein thiols of the EV-secreting cells from oxidation. As the redox state of protein thiols greatly impacts three-dimensional protein structure and, consequently, function, redox modifications of protein thiols may directly modulate EV release in response to changes in the cell's redox environment. In this review article, we discuss targets of redox-dependent thiol modifications that are known or expected to be involved in the regulation of EV release, namely redox-sensitive calcium channels, N-ethylmaleimide sensitive factor, protein disulfide isomerase, phospholipid flippases, actin filaments, calpains and cell surface-exposed thiols. Thiol protection is proposed as a strategy for preventing detrimental changes in EV signaling in response to inflammation and oxidative stress. Identification of the thiol-containing proteins that modulate EV release in pro-oxidant environments could provide a rationale for broad application of thiol group-containing antioxidants in chronic inflammatory diseases.

Masquelier's grape seed extract: from basic flavonoid research to a well-characterized food supplement with health benefits.

Careful characterization and standardization of the composition of plant-derived food supplements is essential to establish a cause-effect relationship between the intake of that product and its health effect. In this review we follow a specific grape seed extract containing monomeric and oligomeric flavan-3-ols from its creation by Jack Masquelier in 1947 towards a botanical remedy and nutraceutical with proven health benefits. The preparation's research history parallels the advancing insights in the fields of molecular biology, medicine, plant and nutritional sciences during the last 70 years. Analysis of the extract's flavanol composition emerged from unspecific colorimetric assays to precise high performance liquid chromatography - mass spectrometry and proton nuclear magnetic resonance fingerprinting techniques. The early recognition of the preparation's auspicious effects on the permeability of vascular capillaries directed research to unravel the underlying cellular and molecular mechanisms. Recent clinical data revealed a multitude of favorable alterations in the vasculature upon an 8 weeks supplementation which summed up in a health benefit of the extract in healthy humans. Changes in gene expression of inflammatory pathways in the volunteers' leukocytes were suggested to be involved in this benefit. The historically grown scientific evidence for the preparation's health effects paves the way to further elucidate its metabolic fate and molecular action in humans.

Time in Redox Adaptation Processes: From Evolution to Hormesis.

Life on Earth has to adapt to the ever changing environment. For example, due to introduction of oxygen in the atmosphere, an antioxidant network evolved to cope with the exposure to oxygen. The adaptive mechanisms of the antioxidant network, specifically the glutathione (GSH) system, are reviewed with a special focus on the time. The quickest adaptive response to oxidative stress is direct enzyme modification, increasing the GSH levels or activating the GSH-dependent protective enzymes. After several hours, a hormetic response is seen at the transcriptional level by up-regulating Nrf2-mediated expression of enzymes involved in GSH synthesis. In the long run, adaptations occur at the epigenetic and genomic level; for example, the ability to synthesize GSH by phototrophic bacteria. Apparently, in an adaptive hormetic response not only the dose or the compound, but also time, should be considered. This is essential for targeted interventions aimed to prevent diseases by successfully coping with changes in the environment e.g., oxidative stress.

Food-Derived Bioactives Can Protect the Anti-Inflammatory Activity of Cortisol with Antioxidant-Dependent and -Independent Mechanisms.

In chronic inflammatory diseases the anti-inflammatory effect of glucocorticoids (GCs) is often decreased, leading to GC resistance. Inflammation is related with increased levels of reactive oxygen species (ROS), leading to oxidative stress which is thought to contribute to the development of GC resistance. Plant-derived compounds such as flavonoids are known for their ability to protect against ROS. In this exploratory study we screened a broad range of food-derived bioactives for their antioxidant and anti-inflammatory effects in order to investigate whether their antioxidant effects are associated with the ability to preserve the anti-inflammatory effects of cortisol. The anti-inflammatory potency of the tested compounds was assessed by measuring the oxidative stress-induced GC resistance in human macrophage-like cells. Cells were pre-treated with H2O2 (800 µM) with and without bioactives and then exposed to lipopolysaccharides (LPS) (10 ng/mL) and cortisol (100 nM). The level of inflammation was deducted from the concentration of interleukin-8 (IL-8) in the medium. Intracellular oxidative stress was measured using the fluorescent probe 2',7'-dichlorofluorescein (DCFH). We found that most of the dietary bioactives display antioxidant and anti-inflammatory action through the protection of the cortisol response. All compounds, except for quercetin, revealing antioxidant activity also protect the cortisol response. This indicates that the antioxidant activity of compounds plays an important role in the protection of the GC response. However, next to the antioxidant activity of the bioactives, other mechanisms also seem to be involved in this protective, anti-inflammatory effect.

The cocoa flavanol (-)-epicatechin protects the cortisol response.

Various health benefits of the cocoa flavanol (-)-epicatechin (EC) have been attributed to its antioxidant and anti-inflammatory potency. In the present study we investigated whether EC is able to prevent deterioration of the anti-inflammatory effect of the glucocorticoid (GC) cortisol in the presence of oxidative stress. It was found that cortisol reduces inflammation in differentiated monocytes. Oxidative stress extinguishes the anti-inflammatory effect of cortisol, leading to cortisol resistance. EC reduces intracellular oxidative stress as well as the development of cortisol resistance. This further deciphers the enigmatic mechanism of EC by which it exerts its anti-inflammatory and antioxidant action. The observed effect of the cocoa flavanol EC will especially be of relevance in pathophysiological conditions with increased oxidative stress and consequential GC resistance and provides a fundament for the rational use of dietary antioxidants.

Galacto-oligosaccharides supplementation in prefrail older and healthy adults increased faecal bifidobacteria, but did not impact immune function and oxidative stress.

BACKGROUND & AIMS: Ageing is associated with an increased risk of frailty, intestinal microbiota perturbations, immunosenescence and oxidative stress. Prebiotics such as galacto-oligosaccharides (GOS) may ameliorate these ageing-related alterations. We aimed to compare the faecal microbiota composition, metabolite production, immune and oxidative stress markers in prefrail elderly and younger adults, and investigate the effects of GOS supplementation in both groups. METHODS: In a randomised controlled cross-over study, 20 prefrail elderly and 24 healthy adults received 21.6 g/day Biotis™ GOS (containing 15.0 g/day GOS) or placebo. Faecal 16S rRNA gene-based microbiota and short-chain fatty acids were analysed at 0, 1 and 4 weeks of intervention.Volatile organic compounds were analysed in breath, and stimulated cytokine production, CRP, malondialdehyde, trolox equivalent antioxidant capacity (TEAC) and uric acid (UA) in blood at 0 and 4 weeks. RESULTS: Principle coordinate analysis showed differences in microbial composition between elderly and adults (P≤0.05), with elderly having lower bifidobacteria (P≤0.033) at baseline. In both groups, GOS affected microbiota composition (P≤0.05), accompanied by increases in bifidobacteria (P<0.001) and decreased microbial diversity (P≤0.023). Faecal and breath metabolites, immune and oxidative stress markers neither differed between groups (P ≥ 0.125) nor were affected by GOS (P ≥ 0.236). TEAC values corrected for UA were higher in elderly versus adults (P<0.001), but not different between interventions (P ≥ 0.455). CONCLUSIONS: Elderly showed lower faecal bifidobacterial (relative) abundance than adults, which increased after GOS intake in both groups. Faecal and breath metabolites, parameters of immune function and oxidative stress were not different at baseline, and not impacted by GOS supplementation. CLINICALTRIALS. GOV WITH STUDY ID NUMBER: NCT03077529.

Oxidative stress and antioxidants in interstitial lung disease.

PURPOSE OF REVIEW: The cause of interstitial lung diseases (ILDs) such as lung fibrosis or sarcoidosis is still largely unknown. Pharmacotherapeutic treatment in ILD lacks a firm mechanistic molecular basis. A striking paradox is that ILDs result in a shortage of oxygen and that at the same time reactive oxygen species are responsible for the tissue damage in ILDs. The realization of the importance of reactive oxygen species offers new possibilities for therapeutic interventions. RECENT FINDINGS: Remarkably, the two drugs that have been shown to be the most effective ones in the treatment of lung fibrosis are in fact antioxidants that protect against the toxicity of oxygen. Redox cycling drugs that are notorious oxygen radical generators may also cause ILD. Apart from lung fibrosis, sarcoidosis also has recently been associated with the occurrence of oxidative stress. SUMMARY: The limited number of ILD patients necessitates multicenter trials to obtain enough power to reach clinically relevant data. The specific fibrotic toxicity of O2. might be a lead in the development of new therapies and of suggesting optimal antioxidant dietary regimes.

Oxidative stress and vascular function: implications for pharmacologic treatments.

Production of considerable amounts of reactive oxygen species (ROS) eventually leads to oxidative stress. A key role of oxidative stress is evident in the pathologic mechanisms of endothelial dysfunction and associated cardiovascular diseases. Vascular enzymes such as NADPH oxidases, xanthine oxidase, and uncoupled endothelial nitric oxide synthase are involved in the production of ROS. The question remains whether pharmacologic approaches can effectively combat the excessive ROS production in the vasculature. Interestingly, existing registered cardiovascular drugs can directly or indirectly act as antioxidants, thereby preventing the damaging effects of ROS. Moreover, new compounds targeting NADPH oxidases have been developed. Finally, food-derived compounds appear to be effective inhibitors of oxidative stress and preserve vascular function.

Dietary Advanced Glycation Endproducts Decrease Glucocorticoid Sensitivity In Vitro.

Glucocorticoids are very effective anti-inflammatory drugs and widely used for inflammatory bowel disease (IBD) patients. However, approximately 20% of IBD patients do not respond to glucocorticoids and the reason for this is largely unknown. Dietary advanced glycation endproducts (AGEs) are formed via the Maillard reaction during the thermal processing of food products and can induce a pro-inflammatory reaction in human cells. To investigate whether this pro-inflammatory response could be mitigated by glucocorticoids, human macrophage-like cells were exposed to both LPS and AGEs to induce interleukin-8 (IL8) secretion. This pro-inflammatory response was then modulated by adding pharmacological compounds interfering in different steps of the anti-inflammatory mechanism of glucocorticoids: rapamycin, quercetin, and theophylline. Additionally, intracellular reactive oxygen species (ROS) were measured and the glucocorticoid receptor phosphorylation state was assessed. The results show that AGEs induced glucocorticoid resistance, which could be mitigated by quercetin and rapamycin. No change in the phosphorylation state of the glucocorticoid receptor was observed. Additionally, intracellular ROS formation was induced by AGEs, which was mitigated by quercetin. This suggests that AGE-induced ROS is an underlying mechanism to AGE-induced glucocorticoid resistance. This study shows for the first time the phenomenon of dietary AGE-induced glucocorticoid resistance due to the formation of ROS. Our findings indicate that food products with a high inflammatory potential can induce glucocorticoid resistance; these results may be of great importance to IBD patients suffering from glucocorticoid resistance.

Effects of Monomeric and Oligomeric Flavanols on Kidney Function, Inflammation and Oxidative Stress in Runners: A Randomized Double-Blind Pilot Study.

Nonsteroidal anti-inflammatory drugs are frequently used by athletes in order to prevent musculoskeletal pain and improve performance. In combination with strenuous exercise, they can contribute to a reduction of renal blood flow and promote development of kidney damage. We aimed to investigate whether monomeric and oligomeric flavanols (MOF) could reduce the severity of kidney injuries associated with the intake of 400-mg ibuprofen followed by the completion of a half-marathon in recreational athletes. In this double-blind, randomized study, the original MOF blend of extracts from grape seeds (Vitis vinifera L.) and pine bark (Pinus pinaster L.) or placebo were taken for 14 days preceding the ibuprofen/half-marathon. Urine samples were collected before and after the ibuprofen/half-marathon, and biomarkers of kidney injury, inflammation and oxidative stress were assessed. Intake of MOF significantly reduced the incidence of post-race hematuria (p = 0.0004) and lowered concentrations of interleukin (IL)-6 in the urine (p = 0.032). Urinary neutrophil-associated lipocalin, creatine, albumin, IL-8 and malondialdehyde tended to decrease. The supplementation with MOF in recreational runners appears to safely preserve kidney function, reduce inflammation and promote antioxidant defense during strenuous exercise and intake of a single dose of ibuprofen.

(-)-Epicatechin metabolites promote vascular health through epigenetic reprogramming of endothelial-immune cell signaling and reversing systemic low-grade inflammation.

Ingestion of (-)-epicatechin flavanols reverses endothelial dysfunction by increasing flow mediated dilation and by reducing vascular inflammation and oxidative stress, monocyte-endothelial cell adhesion and transendothelial monocyte migration in vitro and in vivo. This involves multiple changes in gene expression and epigenetic DNA methylation by poorly understood mechanisms. By in silico docking and molecular modeling we demonstrate favorable binding of different glucuronidated, sulfated or methylated (-)-epicatechin metabolites to different DNA methyltransferases (DNMT1/DNMT3A). In favor of this model, genome-wide DNA methylation profiling of endothelial cells treated with TNF and different (-)-epicatechin metabolites revealed specific DNA methylation changes in gene networks controlling cell adhesion-extravasation endothelial hyperpermeability as well as gamma-aminobutyric acid, renin-angiotensin and nitric oxide hypertension pathways. Remarkably, blood epigenetic profiles of an 8 weeks intervention with monomeric and oligomeric flavanols (MOF) including (-)-epicatechin in male smokers revealed individual epigenetic gene changes targeting similar pathways as the in vitro exposure experiments in endothelial cells. Furthermore, epigenetic changes following MOF diet intervention oppose atherosclerosis associated epigenetic changes. In line with biological data, the individual epigenetic response to a MOF diet is associated with different vascular health parameters (glutathione peroxidase 1 and endothelin-1 expression, acetylcholine-mediated microvascular response), in part involving systemic shifts in blood immune cell types which reduce the neutrophil-lymphocyte ratio (NLR). Altogether, our study suggests that different (-)-epicatechin metabolites promote vascular health in part via epigenetic reprogramming of endothelial-immune cell signaling and reversing systemic low-grade inflammation.

Poly (ADP-ribose) polymerase-1-inhibiting flavonoids attenuate cytokine release in blood from male patients with chronic obstructive pulmonary disease or type 2 diabetes.

Recently, we identified several flavonoids as inhibitors of the nuclear enzyme poly(ADP-ribose) polymerase (PARP)-1 in vitro and in vivo. PARP-1 is recognized as coactivator of nuclear factor-kappaB and plays a role in the pathophysiology of diseases with low-grade systemic inflammation, such as chronic obstructive pulmonary disease (COPD) and type 2 diabetes (T2D). In this study, we assessed the antiinflammatory effects of flavonoids with varying PARP-1-inhibiting effects in whole blood from male patients with COPD or T2D and healthy men. A total of 10 COPD, 10 T2D patients, and 10 healthy volunteers matched for age and BMI were recruited. Blood from each participant was exposed to 1 microg/L lipopolysaccharide (LPS) over 16 h with or without preincubation with 10 micromol/L of flavone, fisetin, morin, or tricetin. Concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, -8, and -10 were measured in the supernatant. Preincubation with fisetin and tricetin strongly attenuated LPS-induced increases in concentrations of TNFalpha in blood from COPD patients [mean (+/- SEM): -41 +/- 4% (fisetin) and -31 +/- 4% (tricetin); P < 0.001] and IL-6 in blood from T2D patients [-31 +/- 5% (fisetin) and -29 +/- 6% (tricetin); P < or = 0.001]. Moreover, LPS-induced changes in TNFalpha and IL-6 concentrations were positively correlated with the extent of reduction by fisetin and tricetin. The PARP-1-inhibiting flavonoids fisetin and tricetin were able to attenuate LPS-induced cytokine release from leukocytes of patients with chronic systemic inflammation, indicating a potential application as nutraceutical agents for these patient groups.

Measuring the glycemic index of foods: interlaboratory study.

BACKGROUND: Many laboratories offer glycemic index (GI) services. OBJECTIVE: We assessed the performance of the method used to measure GI. DESIGN: The GI of cheese-puffs and fruit-leather (centrally provided) was measured in 28 laboratories (n=311 subjects) by using the FAO/WHO method. The laboratories reported the results of their calculations and sent the raw data for recalculation centrally. RESULTS: Values for the incremental area under the curve (AUC) reported by 54% of the laboratories differed from central calculations. Because of this and other differences in data analysis, 19% of reported food GI values differed by >5 units from those calculated centrally. GI values in individual subjects were unrelated to age, sex, ethnicity, body mass index, or AUC but were negatively related to within-individual variation (P=0.033) expressed as the CV of the AUC for repeated reference food tests (refCV). The between-laboratory GI values (mean+/-SD) for cheese-puffs and fruit-leather were 74.3+/-10.5 and 33.2+/-7.2, respectively. The mean laboratory GI was related to refCV (P=0.003) and the type of restrictions on alcohol consumption before the test (P=0.006, r2=0.509 for model). The within-laboratory SD of GI was related to refCV (P<0.001), the glucose analysis method (P=0.010), whether glucose measures were duplicated (P=0.008), and restrictions on dinner the night before (P=0.013, r2=0.810 for model). CONCLUSIONS: The between-laboratory SD of the GI values is approximately 9. Standardized data analysis and low within-subject variation (refCV<30%) are required for accuracy. The results suggest that common misconceptions exist about which factors do and do not need to be controlled to improve precision. Controlled studies and cost-benefit analyses are needed to optimize GI methodology. The trial was registered at clinicaltrials.gov as NCT00260858.

Dietary arachidonic acid dose-dependently increases the arachidonic acid concentration in human milk.

Lactation hampers normalization of the maternal arachidonic acid (AA) status, which is reduced after pregnancy and can further decline by the presently recommended increased consumption of (n-3) long-chain PUFA [(n-3) LCPUFA]. This may be unfavorable for breast-fed infants, because they also require an optimum supply of (n-6) LCPUFA. We therefore investigated the LCPUFA responses in nursing mothers upon increased consumption of AA and (n-3) LCPUFA. In a parallel, double-blind, controlled trial, lactating women received for 8 wk no extra LCPUFA (control group, n = 8), 200 (low AA group, n = 9), or 400 (high AA group, n = 8) mg/d AA in combination with (n-3) LCPUFA [320 mg/d docosahexaenoic acid (DHA), 80 mg/d eicosapentaenoic acid, and 80 mg/d other (n-3) fatty acids], or this dose of (n-3) LCPUFA alone [DHA + eicosapentaenoic acid group, n = 8]. Relative concentrations of AA, DHA, and sums of (n-6) and (n-3) LCPUFA were measured in milk total lipids (TL) and erythrocyte phospholipids (PL) after 2 and 8 wk and changes were compared by ANCOVA. The combined consumption of AA and (n-3) LCPUFA caused dose-dependent elevations of AA and total (n-6) LCPUFA concentrations in milk TL and did not significantly affect the DHA and total (n-3) LCPUFA increases caused by (n-3) LCPUFA supplementation only. This latter treatment did not significantly affect breast milk AA and total (n-6) LCPUFA concentrations. AA and DHA concentrations in milk TL and their changes were strongly and positively correlated with their corresponding values in erythrocyte PL (r(2) = 0.27-0.50; P

Gum arabic establishes prebiotic functionality in healthy human volunteers in a dose-dependent manner.

The present study was undertaken to determine the prebiotic efficacy of gum arabic upon consumption by man for up to 4 weeks and, if any, to establish the dose-effect relationship. Human healthy volunteers consumed various daily doses (5, 10, 20, 40 g) of gum arabic (EmulGold) in water for up to 4 weeks. Daily consumption of water was taken as the negative control and that of 10 g inulin as the positive control. At 0, 1, 2 and 4 weeks quantification of bacterial numbers in stool samples was performed via real time-PCR techniques and questionnaires were filled in to account for potential drawbacks. The genera of Bifidobacteria and Lactobacilli were taken as potentially beneficial bacteria and those of Bacteroides, Clostridium difficile and Enterococci as potentially non-beneficial, this distinction was dependent on the issue of these numbers being or becoming out of balance in the host. Compared with the negative control the numbers of Bifidobacteria and Lactobacilli 4 weeks after consumption were significantly higher for gum arabic: the optimal dose being around 10 g. Moreover, at this dose the numbers of Bifidobacteria, Lactobacilli and Bacteroides were significantly higher for gum arabic than for inulin. No significant drawback was encountered during the study. It is concluded that gum arabic establishes prebiotic efficacy, at least as good as inulin. The optimal daily dose was found to be 10 g.

Monomeric and oligomeric flavanols maintain the endogenous glucocorticoid response in human macrophages in pro-oxidant conditions in vitro.

Chronic inflammation and oxidative stress are (sub)cellular processes that enhance each other and contribute to the genesis of many systemic pathologies. The endogenous glucocorticoid cortisol plays an important role in the physiological termination of a pro-inflammatory immune response. However, in conditions of pronounced oxidative stress the anti-inflammatory action of cortisol is impaired. Since grape seed-derived monomeric and oligomeric flavan-3-ols (MOF) have been shown to attenuate both inflammation and oxidative stress in vitro and in humans, we hypothesized that these compounds are able to maintain the anti-inflammatory activity of cortisol in immune cells in a pro-oxidant environment. In a glucocorticoid resistance model using human monocytes (THP-1 cell line) differentiated into macrophage-like cells we observed that exposure to 1 mM tertiary butyl hydroperoxide (t-BuOOH) for 4 h significantly hampered the anti-inflammatory action of cortisol assessed as attenuation of the interleukin (IL)-8 production. Under these conditions, the effects of MOF were assessed on pro-inflammatory cytokines expression, cortisol's anti-inflammatory action and on the expression of 11ß-hydroxysteroid dehydrogenase (11ß-HSD) 1, which catalyzes intracellular conversion of cortisone to cortisol. MOF attenuated the gene expression of pro-inflammatory cytokines and prevented the decline of the anti-inflammatory effect of cortisol in the presence of t-BuOOH. MOF also maintained the activity of histone deacetylase in the cell nucleus which is essential for cortisol's molecular action to terminate the transcription of pro-inflammatory genes. Moreover, MOF prevented the down-regulation of 11ß-HSD1 gene expression in this pro-oxidant cellular environment. Taken together our data suggest that MOF contribute to maintain the anti-inflammatory action of cortisol under pro-oxidant conditions via preservation of the intracellular availability of bioactive cortisol and cortisol-mediated termination of pro-inflammatory gene transcription. These findings provide novel insights in how MOF may enhance the ability to adapt, which is of particular relevance for their rational use as dietary supplement to maintain health.

Dietary Advanced Glycation Endproducts Induce an Inflammatory Response in Human Macrophages in Vitro.

Advanced glycation endproducts (AGEs) can be found in protein- and sugar-rich food products processed at high temperatures, which make up a vast amount of the Western diet. The effect of AGE-rich food products on human health is not yet clear and controversy still exists due to possible contamination of samples with endotoxin and the use of endogenous formed AGEs. AGEs occur in food products, both as protein-bound and individual molecules. Which form exactly induces a pro-inflammatory effect is also unknown. In this study, we exposed human macrophage-like cells to dietary AGEs, both in a protein matrix and individual AGEs. It was ensured that all samples did not contain endotoxin concentrations > 0.06 EU/mL. The dietary AGEs induced TNF-alpha secretion of human macrophage-like cells. This effect was decreased by the addition of N(ε)-carboxymethyllysine (CML)-antibodies or a receptor for advanced glycation endproducts (RAGE) antagonist. None of the individual AGEs induce any TNF-alpha, indicating that AGEs should be bound to proteins to exert an inflammatory reaction. These findings show that dietary AGEs directly stimulate the inflammatory response of human innate immune cells and help us define the risk of regular consumption of AGE-rich food products on human health.

The direct and sustained consequences of severe placental hypoxia on vascular contractility.

INTRODUCTION: Preeclampsia is a major health problem in human pregnancy, severely complicating 5-8% of all pregnancies. The emerging molecular mechanism is that conditions like hypoxic stress trigger the release of placental messengers into the maternal circulation, which causes preeclampsia. Our objective was to develop an in vitro model, which can be used to further elucidate the molecular mechanisms of preeclampsia and which might be used to find a remedy. METHODS: Human non-complicated term placentas were collected. Placental explants were subjected to severe hypoxia and the conditioned media were added to chorionic arteries that were mounted into a myograph. Contractile responses of the conditioned media were determined, as well as effects on thromboxane-A2 (U46619) induced contractility. To identify the vasoactive compounds present in the conditioned media, specific receptor antagonists were evaluated. RESULTS: Factors released by placental explants generated under severe hypoxia induced an increased vasoconstriction and vascular contractility to thromboxane-A2. It was found that agonists for the angiotensin-I and endothelin-1 receptor released by placental tissue under severe hypoxia provoke vasoconstriction. The dietary antioxidant quercetin could partially prevent the acute and sustained vascular effects in a concentration-dependent manner. DISCUSSION: Both the acute vasoconstriction, as well as the increased contractility to U46619 are in line with the clinical vascular complications observed in preeclampsia. Data obtained with quercetin supports that our model opens avenues for e.g. nutritional interventions aimed at treating or preventing preeclampsia.

One-week cocoa flavanol intake increases prefrontal cortex oxygenation at rest and during moderate-intensity exercise in normoxia and hypoxia.

During exercise in hypoxia, O2 delivery to brain and muscle is compromised, and oxidative stress is elicited. Cocoa flavanols (CF) have antioxidant capacities and can increase blood flow by stimulating endothelial function. We aimed to examine the effects of 7-day CF intake on oxidative stress, nitric oxide production, and tissue oxygenation in response to exercise in normobaric hypoxia (14.3% O2). In a randomized, double-blind, cross-over study, 14 well-trained male cyclists completed four trials: exercise in normoxia or hypoxia, after 7-day CF or placebo intake. Flow-mediated dilation (FMD) was measured before intake of the last dose CF or placebo. One hundred minutes later, 20-min steady-state (SS; 45% V̇o2max) and 20-min time trial (TT) (cycling) were performed. Blood samples were taken. Prefrontal and muscular oxygenation was assessed by near-infrared spectroscopy. At baseline, FMD was increased by CF. Hypoxia increased exercise-induced elevations in lipid peroxidation and antioxidant capacity. CF suppressed exercise-induced lipid peroxidation but did not influence antioxidant capacity. At rest and during SS, prefrontal and muscular oxygenation was decreased by hypoxia. CF elevated prefrontal oxygenation but did not impact muscular oxygenation. During TT, hypoxia accelerated the exercise-induced decrease in prefrontal oxygenation, but not in muscular oxygenation. During TT, CF did not alter prefrontal and muscular oxygenation. CF did not change plasma nitrite, nitrate, and arginine:citrulline. During high-intensity exercise, CF improved neither tissue oxygenation nor performance in well-trained athletes. At rest and during moderate-intensity exercise, CF reduced exercise-induced lipid peroxidation and partially restored the hypoxia-induced decline in prefrontal oxygenation. NEW & NOTEWORTHY For the first time, we showed that CF had beneficial effects on endothelial function at rest, as well as on prefrontal oxygenation at rest and during moderate-intensity exercise, both in normoxia and hypoxia. Moreover, we showed that CF intake inhibited oxidative stress during exhaustive exercise in hypoxia.