Archive for October, 2008

EVEN MILD SLEEP APNEA INCREASES CARIOVASCULAR RISK

Friday, October 24th, 2008

People with even minimally symptomatic obstructive sleep apnea (OSA) may be at increased risk for cardiovascular disease because of impaired endothelial function and increased arterial stiffness, according to a study from the Oxford Centre for Respiratory Medicine in the UK.

“It was previously known that people with OSA severe enough to affect their daytime alertness and manifest in other ways are at increased risk of cardiovascular disease, but this finding suggests that many more people - some of whom may be completely unaware that they even have OSA - are at risk than previously thought,” said lead author of the study, Malcolm Kohler, M.D.

The study will be published in the first issue for November of the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine.

“Only one out of approximately five subjects with [clinically defined OSA] complains of excessive daytime sleepiness in population studies,” wrote Geraldo Lorenzi-Filho, M.D., Ph.D. in an editorial in the same issue of the Journal. “[I]t is now recognized that OSA triggers a cascade of biological reactions, including increased sympathetic activity, systemic inflammation, oxidative stress, and metabolic alterations that are potentially harmful to the cardiovascular system.”

To determine the exact nature of some of these effects, Dr. Kohler and colleagues performed a controlled, cross-sectional study to assess differences in endothelial function (often a harbinger for cardiovascular problems to come), arterial stiffness and blood pressure in patients with minimally symptomatic OSA. They compared 64 patients who had proven OSA to matched control subjects without OSA.

Their findings suggested that minimally symptomatic OSA is a cardiovascular risk factor to a degree not previously known.

“In our study, the augmentation index, a measure of central arterial stiffness that independently predicts cardiovascular events in high-risk populations, was significantly higher in patients with minimally symptomatic OSA compared to matched controls,” said Dr. Kohler. “We also found impaired endothelial function as indicated by decreased vascular reactivity of their arteries compared to control subjects without OSA.”

The difference in arterial stiffness between OSA patients and control subjects, Dr. Kohler said was “comparable in size to the effect seen after four weeks’ continuous positive airway pressure (CPAP) therapy in patients with moderate to severe symptomatic OSA.”

This suggests that asymptomatic or minimally symptomatic patients with OSA may enjoy a cardiovascular benefit from CPAP therapy.

Dr.Kohler and colleagues from the Oxford Centre for Respiratory Medicine are currently investigating the effects of 6 month CPAP therapy on arterial stiffness and endothelial function as part of an international randomized controlled trial (Multicentre Obstructive Sleep Apnoea Interventional Cardiovascular Trial; MOSAIC) which will show the impact of CPAP therapy on cardiovascular risk in patients with minimally symptomatic OSA.

Press release - thorcic.org

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BRAZIL CONFERENCE ON RAINFOREST

Saturday, October 18th, 2008

The Head of Geography at the University of Leicester has addressed an international conference in Brazil on the use of modern radar technology for monitoring the rainforests.

Professor Heiko Balzter told 200 scientists and foresters in Brazil “We need advanced radar satellites for monitoring tropical deforestation and forest biomass”.

The researchers from South America, the US, Canada and Europe had come together for the 8th Seminar on Remote Sensing and Geographical Information Systems Applications in Forest Engineering in the city of Curitiba, Brazil.

Read more in our HeartVigor.com Green Living News Page.

DRUG MAY REDUCE CORONARY ARTERY PLAQUE

Sunday, October 12th, 2008

Tests of medication used to treat high blood pressure suggest positive role in potential plaque regressionWASHINGTON, DC - Research presented at the 20th annual Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium, sponsored by the Cardiovascular Research Foundation (CRF), suggests that olmesartan, a drug commonly used to treat high blood pressure, may play a role in reducing coronary plaque.

The trial, “Impact of OLmesartan on progression of coronary atherosclerosis; evaluation by IVUS [OLIVUS], was performed on 247 angina patients with native coronary artery lesions. Patients were randomly assigned to receive 20-40mg/day of olmesartan or control, and treated with a combination of beta-blockers, calcium channel blockers, diuretics, nitrates, glycemic control agents and/or statins per physician’s guidance.

Serial Intravenous Ultrasound (IVUS) examinations were performed to assess the amount of coronary plaque before and 14 months after the start of treatment.

At the start of the trial, patient characteristics and all IVUS measurements were identical between the two groups. However, after 14 months of treatment, IVUS showed significant decreases in measurements of plaque volume in the olmesartan group, despite similar blood pressure readings.

In addition, multivariate analysis identified olmesartan administration as one of the factors that caused the decrease in plaque volume.

“Management of plaque is a key front in the war on sudden heart attack,” said Atsushi Hirohata, M.D, Ph.D, Cardiovascular Medicine, the Sakakibara Heart Institute of Okayama, Okayama, Japan and lead author of the study. “These results suggest a positive role in potential plaque regression through the administration of olmesartan, an angiotension-II receptor blocking agent, for patients with stable angina pectoris.”

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TO PROTECT THE ENVIRONMENT, BIOFUEL STANDARDS ARE NEEDED

Friday, October 10th, 2008

Society is in a race to find renewable sources of carbon-neutral energy. Cellulose-based biofuels hold promise, but we need to proceed cautiously and with an eye toward minimizing long-term ecological impacts. Without a sound plan, we could wind up doing more environmental harm than good.

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The United States lacks the policies needed to ensure that cellulosic biofuel production will not cause environmental harm, says a distinguished group of international scientists. The paper, published in the October 3rd issue of the journal Science, urges decision makers to adopt standards and incentives that will help ensure that future production efforts are sustainable, both energetically and environmentally.

Because the cellulosic biofuel industry is young, policymakers have the opportunity to implement science-based standards before large scale crop production begins. Early preventative polices could play a major role in minimizing the unintentional side effects of large-scale crop production, such as fertilizer and pesticide pollution, soil erosion, invasive species spread, the fouling of waterways, and species loss.

Dr. Kathleen Weathers, an ecosystem scientist at the Cary Institute of Ecosystem Studies and one of the paper’s authors, comments, “Society is in a race to find renewable sources of carbon-neutral energy. Cellulose-based biofuels hold promise, but we need to proceed cautiously and with an eye toward minimizing long-term ecological impacts. Without a sound plan, we could wind up doing more environmental harm than good.”

Grain-based ethanol has already served as a lesson in the perils of embracing energy solutions before their environmental effects are understood. Most of the commercial ethanol produced in the United States is made from corn. When large parts of the landscape are converted to such resource-intensive, monoculture grain crops, as is the current model, the scientific consensus is that the environment suffers.

Moving forward, if cellulosic ethanol is to emerge as a feasible source of renewable energy, a vast amount of land will need to be used for its production. This land conversion - estimated to be as large as the amount of land in row-crops today - will change the face of the global landscape. Production standards and incentive programs could help minimize negative impacts and, in many cases, help farmers choose crops that provide valuable ecosystem services.

Weathers notes, “There is the real potential for science to inform sustainable cellulosic crop strategies; it’s about picking the right plant, or assemblage of plants, for a given landscape and managing crops in a minimally invasive way.” No-till farming can slow erosion and enrich soil; cover crops can sequester soil carbon and minimize nutrient run-off; and buffers can support beneficial insects such as pollinators.

But this won’t happen without making environmentally sustainable growing practices widely available and establishing incentives to farmers that adopt the techniques. The authors stress that as the technology to make cellulosic biofuels improves, and efforts become commercialized, both industry and legislators must adopt policies that reward sustainable crop production.

This is one of the first times such a large and diverse group of internationally recognized scientists have spoken with one voice on the issue. The 23 authors - some of the world’s top ecologists, agronomists, conservation biologists and economists - encompass diverse backgrounds and professional experiences.

Weathers concludes, “Incentives, such as substantial subsidies for cellulosic ethanol production, could send us hurtling down an environmentally tenuous path. I hope decision makers heed our recommendations. They emerged from a collaborative effort that cut across disciplines and ideologies, and we came to a strong scientific consensus.”

Press release Oct. 9, 2008 - Cary Institute of Ecosystem Studies.