Efficacy of a family practice-based lifestyle intervention program to increase physical activity and reduce clinical and physiological markers of vascular health in patients with high normal blood pressure and/or high normal blood glucose (SNAC): study protocol for a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Previous interventions to increase physical activity and reduce cardiovascular risk factors have been targeted at individuals with established disease; less attention has been given to intervention among individuals with high risk for disease nor has there been determination of the influence of setting in which the intervention is provided. In particular, family practice represents an ideal setting for the provision and long-term maintenance of lifestyle interventions for patients at risk (ie high-normal blood pressure or impaired glucose tolerance).</p> <p>Methods/design</p> <p>The Staged Nutrition and Activity Counseling (SNAC) study is a randomized clustered design clinical trial that will investigate the effectiveness and efficacy of a multi-component lifestyle intervention on cardiovascular disease risk factors and vascular function in patients at risk in primary care. Patients will be randomized by practice to either a standard of care lifestyle intervention or a behaviourally-based, matched prescriptive physical activity and diet change program. The primary goal is to increase physical activity and improve dietary intake according to Canada's Guides to Physical Activity Healthy Eating over 24 months. The primary intention to treat analysis will compare behavioral, physiological and metabolic outcomes at 6, 12 and 24 months post-randomization including estimation of incident hypertension and/or diabetes.</p> <p>Discussion</p> <p>The design features of our trial, and the practical problems (and solutions) associated with implementing these design features, particularly those that result in potential delay between recruitment, baseline data collection, randomization, intervention, and assessment will be discussed. Results of the SNAC trial will provide scientific rationale for the implementation of this lifestyle intervention in primary care.</p> <p>Trial registration</p> <p>ISRCTN: <a href="http://www.controlled-trials.com/ISRCTN:42921300">ISRCTN:42921300</a></p

Earth: Atmospheric Evolution of a Habitable Planet

Our present-day atmosphere is often used as an analog for potentially habitable exoplanets, but Earth's atmosphere has changed dramatically throughout its 4.5 billion year history. For example, molecular oxygen is abundant in the atmosphere today but was absent on the early Earth. Meanwhile, the physical and chemical evolution of Earth's atmosphere has also resulted in major swings in surface temperature, at times resulting in extreme glaciation or warm greenhouse climates. Despite this dynamic and occasionally dramatic history, the Earth has been persistently habitable--and, in fact, inhabited--for roughly 4 billion years. Understanding Earth's momentous changes and its enduring habitability is essential as a guide to the diversity of habitable planetary environments that may exist beyond our solar system and for ultimately recognizing spectroscopic fingerprints of life elsewhere in the Universe. Here, we review long-term trends in the composition of Earth's atmosphere as it relates to both planetary habitability and inhabitation. We focus on gases that may serve as habitability markers (CO2, N2) or biosignatures (CH4, O2), especially as related to the redox evolution of the atmosphere and the coupled evolution of Earth's climate system. We emphasize that in the search for Earth-like planets we must be mindful that the example provided by the modern atmosphere merely represents a single snapshot of Earth's long-term evolution. In exploring the many former states of our own planet, we emphasize Earth's atmospheric evolution during the Archean, Proterozoic, and Phanerozoic eons, but we conclude with a brief discussion of potential atmospheric trajectories into the distant future, many millions to billions of years from now. All of these 'Alternative Earth' scenarios provide insight to the potential diversity of Earth-like, habitable, and inhabited worlds.Comment: 34 pages, 4 figures, 4 tables. Review chapter to appear in Handbook of Exoplanet