Sympathectomy potentiates the vasoconstrictor response to nitric oxide synthase inhibition in humans

Objective: Nitric oxide exerts its cardiovascular actions at least in part by modulation of the sympathetic vasoconstrictor tone. There is increasing evidence that nitric oxide inhibits central neural sympathetic outflow, and preliminary evidence suggests that it may also modulate peripheral sympathetic vasoconstrictor tone. Methods: To test this latter concept, in six subjects having undergone thoracic sympathectomy for hyperhydrosis, we compared the vascular responses to systemic l-NMMA infusion (1mg/kg/min over 10 min) in the innervated and the denervated limb. We also studied vascular responses to the infusion of the non-nitric-oxide-dependent vasoconstrictor phenylephrine. Results: l-NMMA infusion evoked a roughly 3-fold larger increase in vascular resistance in the denervated forearm than in the innervated calf. In the denervated forearm, vascular resistance increased by 58±10 percent (X±SE), whereas in the innervated calf it increased only by 21±6 percent (P<0.01, forearm vs. calf). This augmented vasoconstrictor response was specific for l-NMMA, and not related to augmented non-specific vasoconstrictor responsiveness secondary to sympathectomy, because phenylephrine infusion increased vascular resistance similarly in the denervated forearm and the innervated calf (by 24±7, and 29±8 percent, respectively). The augmented vasoconstrictor response was related specifically to denervation, because in control subjects, the vasoconstrictor responses to l-NMMA were comparable in the forearm and the calf. Conclusions: These findings indicate that in the absence of sympathetic innervation, the vasoconstrictor responses to nitric oxide synthase inhibition are augmente

Interaction between cholinergic and nitrergic vasodilation: a novel mechanism of blood pressure control

Objective: Cholinergic vasodilation has been thought to play little if any role in the regulation of blood pressure in humans. Autonomic denervation potentiates the vasoconstriction evoked by nitric oxide synthase inhibition in humans, but the mechanism is unclear. We hypothesized that this may be related to loss of neuronal, non-nitric-oxide-dependent vasodilation. Methods: To test this hypothesis, we examined effects of cholinergic blockade on blood pressure, heart rate and peripheral vascular responses to systemic infusion of the nitric-oxide-dependent vasoconstrictor l-NMMA (0.5 mg/kg/min over 15 min) in eight normal subjects. Results: The l-NMMA-induced increase in mean (±S.E.) arterial pressure was roughly three times larger (P=0.002) in the presence than in the absence of cholinergic blockade (38±6 vs. 13±2 mmHg). Similarly, the increase in systemic and calf vascular resistance was more than twofold larger during l-NMMA-atropine. This potentiation was specific for nitric-oxide-dependent vasoconstriction, because atropine did not alter the responses to phenylephrine infusion. Cholinergic blockade also altered (P=0.004) the heart rate response to nitric oxide synthase inhibition; during l-NMMA alone heart rate decreased by 10±2 beats/min, whereas during l-NMMA-atropine infusion it increased by 14±4 beats/min. Conclusion: Cholinergic mechanisms play an important hitherto unrecognized role in offsetting the hypertension and cardiac sympathetic activation caused by nitric oxide synthase inhibition in humans. Decreased parasympathetic activity and impaired nitric oxide synthesis characterize several cardiovascular disease states, as well as normal aging. The conjunction of these two defects could trigger sudden death and contribute to the hypertension of the elderl

Recommendations for Maximizing the Benefits of the Vernal Pool at Miller Ecological Park

Course Code: ENR 2367This project makes recommendations for what the Miller Ecological Group should do with their land that has a vernal pool and wetlands. This project not only provides the park with a toolbox of the best options available, but also serves as a method of communication that will inform the entire committee of the events and decisions that need to take place. The committee should use the research that has been compiled when choosing the ideal pathway for Miller Ecological Park’s development. Overall, this project provides research and recommendations for the restoration of the vernal pool and wetlands.Academic Major: Environmental ScienceAcademic Major: Forestry, Fisheries, and WildlifeAcademic Major: Environment, Economy, Development, and SustainabilityAcademic Major: Environmental Policy and Decision Makin

School Finance Equity: An Intradistrict Equity Audit

This overview provides a synthesis of a comprehensive study of an intradistrict equity audit of one mid-Atlantic school district. The purpose of this study was to measure the intradistrict distribution of educational resources across elementary, middle, and high schools of one school district through an equity audit to determine whether or not the allocation and distribution of fiscal resources were equitable and adequate. This study utilized publicly available school-level expenditure data to determine the allocation and distribution of resources to expose any existing disparities. The researcher investigated any disparities in per-pupil expenditures, teacher quality, and academic achievement by examining Skrla, et al.’s (2004) three classifications. Being there is no other research study like this to date, the researcher designed and examined the findings to determine any inequities and inadequacies through an a priori lens suggesting differences as slight, moderate, or notable. To rate the differences in funding as slight, moderate, or notable, the researcher created three per-pupil expenditure weighting groups based on Verstegen’s (2008) suggested student enrollment subgroup category weighting recommendations. The researcher’s findings of this study supported slight, moderate, and notable differences in allocation disparities, teacher quality, and an association between funding and academic achievement among the elementary school level, middle school level, and high school level when utilizing the a priori guidelines. This study aimed to add to the body of literature by addressing the gap in research related to intradistrict equity and adequacy of educational funding

Salmeterol for the prevention of high-altitude pulmonary edema.

BACKGROUND: Pulmonary edema results from a persistent imbalance between forces that drive water into the air space and the physiologic mechanisms that remove it. Among the latter, the absorption of liquid driven by active alveolar transepithelial sodium transport has an important role; a defect of this mechanism may predispose patients to pulmonary edema. Beta-adrenergic agonists up-regulate the clearance of alveolar fluid and attenuate pulmonary edema in animal models. METHODS: In a double-blind, randomized, placebo-controlled study, we assessed the effects of prophylactic inhalation of the beta-adrenergic agonist salmeterol on the incidence of pulmonary edema during exposure to high altitudes (4559 m, reached in less than 22 hours) in 37 subjects who were susceptible to high-altitude pulmonary edema. We also measured the nasal transepithelial potential difference, a marker of the transepithelial sodium and water transport in the distal airways, in 33 mountaineers who were prone to high-altitude pulmonary edema and 33 mountaineers who were resistant to this condition. RESULTS: Prophylactic inhalation of salmeterol decreased the incidence of high-altitude pulmonary edema in susceptible subjects by more than 50 percent, from 74 percent with placebo to 33 percent (P=0.02). The nasal potential-difference value under low-altitude conditions was more than 30 percent lower in the subjects who were susceptible to high-altitude pulmonary edema than in those who were not susceptible (P&lt;0.001). CONCLUSIONS: Prophylactic inhalation of a beta-adrenergic agonist reduces the risk of high-altitude pulmonary edema. Sodium-dependent absorption of liquid from the airways may be defective in patients who are susceptible to high-altitude pulmonary edema. These findings support the concept that sodium-driven clearance of alveolar fluid may have a pathogenic role in pulmonary edema in humans and therefore represent an appropriate target for therapy

Acute and Chronic Altitude-Induced Cognitive Dysfunction in Children and Adolescents

OBJECTIVE: To assess whether exposure to high altitude induces cognitive dysfunction in young healthy European children and adolescents during acute, short-term exposure to an altitude of 3450 m and in an age-matched European population permanently living at this altitude. STUDY DESIGN: We tested executive function (inhibition, shifting, and working memory), memory (verbal, short-term visuospatial, and verbal episodic memory), and speed processing ability in: (1) 48 healthy nonacclimatized European children and adolescents, 24 hours after arrival at high altitude and 3 months after return to low altitude; (2) 21 matched European subjects permanently living at high altitude; and (3) a matched control group tested twice at low altitude. RESULTS: Short-term hypoxia significantly impaired all but 2 (visuospatial memory and processing speed) of the neuropsychological abilities that were tested. These impairments were even more severe in the children permanently living at high altitude. Three months after return to low altitude, the neuropsychological performances significantly improved and were comparable with those observed in the control group tested only at low altitude. CONCLUSIONS: Acute short-term exposure to an altitude at which major tourist destinations are located induces marked executive and memory deficits in healthy children. These deficits are equally marked or more severe in children permanently living at high altitude and are expected to impair their learning abilities

Étude, conception et analyse des systèmes de commande pour un lanceur de satellites

Ce mémoire a pour principal objectif d’identifier des concepts de commande d’attitude et de guidage en boucle ouverte pour supporter le développement éventuel d’un lanceur canadien pouvant effectuer la mise en orbite de microsatellites. Une revue de la littérature des différents systèmes impliqués dans l’asservissement d’un lanceur est présentée. Cette revue a permis de cibler les principales difficultés rencontrées pour la commande d’attitude des lanceurs, ainsi que certaines pistes de solutions. Ces difficultés sont principalement la flexion et le ballottement des ergols. Les équations de mouvement de l’attitude d’un lanceur à corps rigide en fonction de l’angle de braquage d’une tuyère sont décrites. Des régulateurs qui stabilisent et asservissent le lanceur flexible en vitesse angulaire et en position angulaire sur le simulateur Simulink® à six degrés de liberté du RDDC Valcartier sont développés. Pour finir, deux techniques de guidage sont expliquées et testées en présence de diverses perturbations.This memoir’s main objective is to identify concepts of attitude control and open loop guidance to support the eventual development of a Canadian launcher, capable of orbiting microsatellites. A literature review of various systems involved in the stabilization of the launcher is presented. This review pinpointed the main difficulties met for attitude control of launch vehicles, as well as some possible solutions. Those are mainly the bending and sloshing of propellant. The attitude equations of motion for a rigid body launcher as a function of the steering angle of a nozzle are described. Controllers that stabilize and control the flexible launcher angular velocity and angular position on the six degrees of freedom DRDC Valcartier Simulink® simulator are devellopped. Finally, two techniques for guidance are explained and tested in presence of various perturbations

Aristophane aujourd’hui

Pouvez-vous présenter l’atelier théâtre de Neuchâtel ? Institut Neuchâtel : Il n’y a pas d’enseignement structuré à Neuchâtel encore. Il y a un séminaire de théâtre qui pose des problèmes théoriques sur des questions sur le spectacle. Par ailleurs, cette année dans ce séminaire des étudiants et des assistants ont lancé le projet de monter Lysistrata d’Aristophane, principalement pour montrer la partie vivante de l’Antiquité. Le séminaire de théâtre qui essaie de se structurer et de s’imposer ..