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Strain On The Brain


Developments to Watch

STRAIN ON THE BRAIN

CONSTANT STRESS MAY BE MORE THAN just nerve-racking. It may kill nerve cells outright, causing a key part of the brain to shrink. Recent studies in rats show that sustained exposure to stress-induced hormones produces permanent damage in the hippocampus, a seahorse-shaped brain structure involved in learning and memory. Now, scientists are finding similar effects in people.

At Washington University in St. Louis, Yvette I. Sheline, an assistant professor of psychiatry, knew that stress hormones such as cortisol are produced during bouts of depression. She wondered whether high levels of the hormones left their stamp on the brain. Using a high-resolution magnetic-resonance scanner, she compared women who had a history of depression with others who did not. She found that the hippocampus was, on average, 12% smaller in women with multiple episodes of depression. Other researchers have discovered similar, small hippocampi in Vietnam vets and child-abuse victims with post-traumatic stress disorder. Sheline admits the smaller hippocampi may be the cause, not the result, of these disorders. But given the animal experiments and new human studies, stress hormones look like bad news for the brain.EDITED BY NEIL GROSS By John CareyReturn to top

A BETTER BREAST SCAN?

WOMEN GENETICALLY disposed to getting breast cancer and those with fibrocystic disease often undergo frequent X-ray screenings. Unfortunately, there is a high ratio of false positive readings, which typically lead to a needle biopsy. That procedure is expensive and can be traumatic.

Research by Eva M. Sevick-Muraca, associate professor of chemical engineering at Purdue University, suggests there may be a better way. She and her colleagues have applied for a patent on a method for exposing tissue to harmless, near-infrared light from low-cost laser diodes. The light would excite tissue molecules, which would then relax back to a ground energy state, releasing fluorescent light. Researchers could analyze the light values using computer programs developed at Purdue to extract biochemical data, such as the oxygen level and acidity of the target tissue. This information, in turn, would provide a window on early-stage tumor development, which is usually missed by mammography and other imaging technologies.

An added benefit: The equipment would be far less expensive than either X-ray or MRI gear. Sevick-Muraca's lab has developed detailed computer models of how such screening would work. The scientists hope to begin large-scale animal trials this year.EDITED BY NEIL GROSSReturn to top

COMPUTER, MAKE ME A...CONVERTIBLE

YOU CAN'T ACCUSE JAMES C. Fischbach of short-term thinking. He's spearheading a 50-year effort called Initiative 2050 to devise a Star Trek-like machine called a "durable product generator" that would create objects of any kind, on command, from a vat of light-sensitive polymers. The idea is to project a 3-D, computer-generated hologram of the desired object into the vat. Polymers exposed to the hologram's focused light would solidify; the rest would remain liquid. Within seconds, a completed object could be pulled from the soup.

The concept leapfrogs an existing technique called stereolithography, which builds solid objects with a laser beam that sweeps back and forth through a mass of light-sensitive polymers. Instead of this bit-by-bit approach, holograms could engender objects all at once, says Fischbach, principal investigator at American Propylaea Corp. in Birmingham, Mich. And special-purpose polymers could yield materials with a variety of properties such as superhard, transparent, and magnetic.

Armed with a $500,000 grant from the U.S. Air Force, American Propylaea has already developed full-color, 3-D images that hover in space. That has attracted the attention of Big Three auto makers. Chrysler, for example, might use holography to speed up auto design, says Michael C. Holmes, a Chrysler computer-systems manager.EDITED BY NEIL GROSS By Peter CoyReturn to top


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