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Blocking Leaky Calcium Channels in the Heart


The public is always shocked when a young athlete, such as Reggie Lewis of the Boston Celtics or Russian figure skater Sergei Grinkov, dies of a heart attack in mid-workout. Questions are inevitably raised about the victim's lifestyle -- which can be a factor. But a Columbia University research team has found new evidence that a genetic defect can bring on some cases of sudden cardiac failure.

Every time the heart contracts, calcium needed for smooth beating is released through channels in the heart cells. Excess calcium, though, can cause the heart to beat irregularly until the muscle wears out. Columbia physiologist Dr. Andrew R. Marks and his team, reporting in the journal Cell, identified a gene that stabilizes the opening and closing of the calcium channels. They then engineered a strain of mice that lack this gene -- and found that their channels often got stuck in the open position. The mice consistently exhibited exercise-induced irregular heartbeats, which can lead to heart failure. Marks says the discovery points the way to therapies for those with a defective gene and the millions who have leaky calcium channels as a result of heart disease. The ability to build new materials from scratch could be the principal benefit of nanotechnology, ushering in a time when researchers no longer have to make do with the stuff in nature's pantry. As evidence, there's the breakthrough described in the June 26 issue of Nature by researchers from IBM, Columbia University, and the University of New Orleans. They coaxed two unlikely partners to assemble themselves into a three-dimensional crystal designed to provide a combination that doesn't exist naturally: magnetism plus light-generating properties. This unique blend stems from nano-particles of iron oxide surrounding lead selenide, a semiconductor that can emit light.

A material that merges magnetic and optical properties could be tomorrow's silicon. And if this one doesn't work, the new self-assembly technique could combine almost any other mix of ingredients. The way tobacco acts on cells cells in the body may inspire medical advances -- even as it continues to kill people who smoke it. Some studies show that nicotine may protect against both Parkinson's and Alzheimer's diseases, and can also boost memory. Now, doctors say, it may be possible to design drugs that retain or enhance nicotine's beneficial properties while ditching bad effects, such as addiction.

Targacept, of Winston-Salem, N.C., was spun out of R.J. Reynolds in 2000 to search for nicotine-related drugs. Scientists at Targacept and elsewhere have discovered that there are 17 genes for so-called nicotinic receptors in the body -- docking sites on the cell surface that attract nicotine. The genes can combine in different ways to create receptor subtypes, many of which regulate brain-signaling chemicals, or neurotransmitters.

The trick for researchers is to create drugs that hit just one receptor subtype and miss the others. To screen drug candidates, Targacept scientists have developed a number of cell lines, each of which makes different receptor subtypes. The result is a full pipeline of drugs. One targets receptors in the colon and is now in Phase II trials for ulcerative colitis. Another is a powerful painkiller, and another is a potent memory-enhancing compound, says CEO J. Donald deBethizy. Human trials for the memory-enhancer are scheduled to start in September. -- Herb-infused wrapping paper? It isn't for eating -- it's for keeping. Researchers at Technion-Israel Institute of Technology have discovered that when traces of basil extract are added to plastic wrapping, the herbal essence slows the growth of a variety of harmful bacteria that can spoil food. The study, published in the Journal of Agricultural & Food Chemistry in May, found the basil wrap extended the shelf life of cheese without passing any basil flavor to the food. The wrap should offer similar benefits for baked goods, fish, fruits, meats, and vegetables.

-- Scientists know that many illegal drugs, as well as alcohol, can cause irreversible brain damage. But according to a recent study, marijuana poses no such threat. Researchers from the University of California at San Diego compared the mental performance of 704 long-term pot smokers, who were tested while not high, with 484 nonusers. They found that even heavy marijuana use did no permanent harm to a variety of key functions including language, reaction time, motor skills, or perceptual and reasoning abilities. The only exception: a small decrease in the pot smokers' ability to learn new information. The findings, published in July's Journal of the International Neuropsychological Society, suggest that short-term use of cannabis for medical purposes is unlikely to cause harmful side effects.


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