 | Faculty Research
1/22/2002 10:05 AMBeachfront Mountains
In several million years, the wide and shallow North American Atlantic coastline should become rocky and mountainous. A 2,000-mile stretch of the United States East Coast is a prime candidate for a subduction fault, resulting in shifting earth, ocean trenches, and coastal upheaval. Research at the University of Minnesota and the Swiss Federal Institute of Technology in Zurich shows that millions of years of river sediment buildup is creating pressure on the ocean floor along the East Coast. Softened by ocean water seeping into soft sedimentary rock, the floor of the Atlantic Ocean eventually will fracture and plunge beneath the North American continental landmass, pushed by the sediment and under pressure from rising land in the middle of the Atlantic. The edge of the continent will ride up, creating mountains, while the subducted plate will produce trenches. Results of a similar, although smaller, subduction can be seen along the Pacific coast from British Columbia to Oregon. Geological models and mathematical calculations estimate that the process will begin in 3 million to 10 million years and take approximately 3 million years to complete. The study, focusing on the role water plays in the equation, was published in the October 19 issue of Science.
Overlooked Outer Arteries
A vascular disease strongly linked to heart attacks and strokes may be seriously underdiagnosed and undertreated, according to a study authored by Dr. Alan Hirsch, a University scientist. Peripheral arterial disease (PAD) is a narrowing of arteries in legs, and sometimes arms, caused by fatty plaque buildup similar to hardening of arteries around the heart. People with PAD face at least a four times greater risk of stroke or heart attack than those without the disease. Researchers looked at 6,979 people in high-risk groups (over age 70 or over 50 with a history of smoking or diabetes). In all, 1,865 had PAD, including 823 who had never been diagnosed. Of the other 1,042, only about half of their primary physicians knew of the previous diagnosis and most had not been prescribed aspirin or other blood-thinning medications. A chief reason so many were overlooked is that leg pain, which has long been considered the classic symptom of PAD, is present only in about 10 percent of those with the disease. Instead, researchers urge doctors to do more ankle and arm blood-pressure checks to screen high-risk patients. The study was published in the September 19 Journal of the American Medical Association.
Heartening Developments
Two University of Minnesota studies offer good news on congestive heart failure, the leading cause of death in the United States. First, results show that a mechanical implant, called a left ventricular assist system, appears highly successful in not only keeping heart-failure patients alive, but also in improving their quality of life. The U was one of several sites that studied the device, which had double the one-year survival compared with drug therapy (52 percent compared with 25 percent). At Fairview-University Medical Center, six of eight patients receiving the device were still alive more than a year later. Results were published in the November 15 issue of the New England Journal of Medicine. Second, U researchers published findings in the December 5 issue of the New England Journal of Medicine that indicate a specific blood pressure medication is highly effective in reducing hospital stays for heart failure. More than 5,000 patients were studied in the largest heart-failure trial ever conducted. Patients who took the medication valsartan had 22 percent fewer subsequent hospitalizations and a survival rate 13 percent higher than those taking a placebo. The drug appears to block a key neurohormone associated with heart-failure deaths. Valsartan s manufacturer, Ciba Pharmaceuticals, sponsored the study. More than a million Americans were hospitalized for heart failure in 2000 up 200 percent from 1980 and about 285,000 died.
|
Print View