A Community-Engaged Assessment of Barriers and Facilitators to Rapid Stroke Treatment.

Treatment for acute ischemic stroke must be initiated within hours of stroke symptom onset, and the sooner it is administered, the better. In South Carolina, 76% of the population can access expert stroke care, and rural hospitals may provide specialized treatment using telemedicine, but many stroke sufferers seek care too late to achieve full benefit. Using a community-engaged approach in a southern rural community, we explored barriers and facilitators to early stroke care and implications for improvement. The Community-Engaged Assessment to facilitate Stroke Elimination (CEASE) study was guided by a community advisory group to ensure community centeredness and local relevance. In a qualitative descriptive study, eight focus groups were conducted including 52 individuals: recent stroke survivors, family members, emergency medical personnel, hospital emergency department staff, primary care providers, and community leaders. From analysis of focus group transcripts came six themes: lack of trust in healthcare system and providers; weak relationships fueled by poor communication; low health literacy; financial limitations related to health care; community-based education; and faith as a message of hope. A hierarchy model for improving early community-based stroke care was developed through consensus dialogue by community representatives and the research team. This model can be used to inform a community-partnered, stakeholder-informed intervention to improve stroke care in a rural southern community with the goal of improving stroke education, care, and outcome. © 2016 Wiley Periodicals, Inc.

Chemistry and antihypertensive effects of tempol and other nitroxides.

Nitroxides can undergo one- or two-electron reduction reactions to hydroxylamines or oxammonium cations, respectively, which themselves are interconvertible, thereby providing redox metabolic actions. 4-Hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (tempol) is the most extensively studied nitroxide. It is a cell membrane-permeable amphilite that dismutates superoxide catalytically, facilitates hydrogen peroxide metabolism by catalase-like actions, and limits formation of toxic hydroxyl radicals produced by Fenton reactions. It is broadly effective in detoxifying these reactive oxygen species in cell and animal studies. When administered intravenously to hypertensive rodent models, tempol caused rapid and reversible dose-dependent reductions in blood pressure in 22 of 26 studies. This was accompanied by vasodilation, increased nitric oxide activity, reduced sympathetic nervous system activity at central and peripheral sites, and enhanced potassium channel conductance in blood vessels and neurons. When administered orally or by infusion over days or weeks to hypertensive rodent models, it reduced blood pressure in 59 of 68 studies. This was accompanied by correction of salt sensitivity and endothelial dysfunction and reduced agonist-evoked oxidative stress and contractility of blood vessels, reduced renal vascular resistance, and increased renal tissue oxygen tension. Thus, tempol is broadly effective in reducing blood pressure, whether given by acute intravenous injection or by prolonged administration, in a wide range of rodent models of hypertension.

Hydrogen peroxide mediates a transient vasorelaxation with tempol during oxidative stress.

Tempol catalyzes the formation of H(2)O(2) from superoxide and relaxes blood vessels. We tested the hypothesis that the generation of H(2)O(2) by tempol in vascular smooth muscle cells during oxidative stress contributes to the vasorelaxation. Tempol and nitroblue tetrazolium (NBT) both metabolize superoxide in vascular smooth muscle cells, but only tempol generates H(2)O(2). Rat pressurized mesenteric arteries were exposed for 20 min to the thromboxane-prostanoid receptor agonist, U-46619, or norepinephrine. During U-46619, tempol caused a transient dilation (22 +/- 2%), whereas NBT was ineffective (2 +/- 1%), and neither dilated vessels constricted with norepinephrine, which does not cause vascular oxidative stress. Neither endothelium removal nor blockade of K(+) channels with 40 mM KCl affected the tempol-induced dilation, but catalase blunted the tempol dilation by 53 +/- 7%. Tempol, but not NBT, increased H(2)O(2) in rat mesenteric vessels detected with dichlorofluorescein. To test physiological relevance in vivo, topical application of tempol caused a transient dilation (184 +/- 20%) of mouse cremaster arterioles exposed to angiotensin II for 30 min, which was not seen with NBT (9 +/- 4%). The vasodilation to tempol was reduced by 68 +/- 6% by catalase. We conclude that the transient relaxation of blood vessels by tempol after prolonged exposure to U-46619 or angiotensin II is mediated in part via production of H(2)O(2) and is largely independent of the endothelium and potassium channels.