J. David Symons

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Epidemiological studies report that quercetin, an antioxidant flavonol found in apples, berries, and onions, is associated with reduced risk of coronary heart disease and stroke. Quercetin supplementation also reduces blood pressure in hypertensive rodents. The efficacy of quercetin supplementation to lower blood pressure in hypertensive humans has never(More)
Thiazolidinediones (TZDs) are PPARgamma activators that exhibit vasculoprotective properties. To determine the vascular function of PPARgamma, we analyzed Tie2Cre/flox and SM22Cre/flox mice. Unexpectedly, both knockout strains exhibited a significant reduction of circadian variations in blood pressure and heart rate in parallel with diminished variations in(More)
The effect of 60 h of sleep deprivation (SD) upon physical performance and physiological responses to exercise was examined in 11 male subjects. The experiment consisted of two conditions separated by at least 10 d. In the experimental condition (E) subjects remained awake for 60 h and in the control condition (C) the same subjects had 7 h of sleep per(More)
Age-associated decline in antioxidant potential and accumulation of reactive oxygen/nitrogen species are primary causes for multiple health problems, including muscular dystrophy and sarcopenia. The role of the nuclear erythroid-2-p45-related factor-2 (Nrf2) signaling has been implicated in antioxidant gene regulation. Here, we investigated the(More)
The intracellular signalling kinases Akt/protein kinase B (Akt), protein kinase A (PKA) and adenosine monophosphate-activated protein kinase (AMPK) are phosphorylated in response to increased mechanical force or perfusion rate in cultured endothelial cells or isolated blood vessels. All three kinases phosphorylate endothelial nitric oxide synthase (eNOS) on(More)
Previous studies suggest that sleep deprivation (SD) decreases glucose tolerance in humans. The present study examined the ability of 10 males to process a glucose load during two conditions separated by at least 10 d. Condition I consisted of sedentary daily activity and sleep deprivation (SDS). Condition II consisted of daily physical activity and sleep(More)
The purpose of this study was to evaluate the effects of glycogen availability on short-term, high-intensity exercise performance. Eight males completed performance evaluation tasks (PET) consisting of maximum isokinetic strength and endurance, isometric strength, and electrically evoked force of the leg extensors, twice during each of two conditions. On(More)
Vascular dysfunction that accompanies obesity and insulin resistance may be mediated by lipid metabolites. We sought to determine if vascular ceramide leads to arterial dysfunction and to elucidate the underlying mechanisms. Pharmacological inhibition of de novo ceramide synthesis, using the Ser palmitoyl transferase inhibitor myriocin, and heterozygous(More)
Quercetin is a polyphenolic flavonoid. Common sources in the diet are apples, onions, berries, and red wine. Epidemiological studies have found an inverse relationship between dietary quercetin intake and cardiovascular disease. This has led to in vitro, in vivo, and clinical research to determine the mechanism by which quercetin exerts cardioprotective(More)
Physical inactivity in older adults is a risk factor for developing glucose intolerance and impaired skeletal muscle function. Elevated inflammation and ceramide biosynthesis have been implicated in metabolic disruption and are linked to Toll-like receptor (TLR)/myeloid differentiation primary response 88 (MyD88) signaling. We hypothesize that a physical(More)