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Developments to Watch
Sleeping on the Right Side of the Brain
A STUDY PUBLISHED IN THIS WEEK'S ISSUE OF NATURE gives new meaning to the phrase "sleeping on the job." Sleep researchers at Indiana State University say most birds have evolved the ability to sleep with one eye open and one half of their brains awake, a phenomenon called unihemispheric sleep. According to Niels C. Rattenborg, the study's lead researcher, this means the birds can get much needed rest while simultaneously watching out for lurking dangers.
To understand when, and why, birds sleep this way, Rattenborg's team videotaped resting mallard ducks. They found that when the ducks were arranged in a row, the end ducks spent three times longer in unihemispheric sleep than their center neighbors. Also, the end ducks controlled which side of the brain slept and which side stayed awake, orienting their open, wakeful eyes toward perceived threats and away from the other ducks. Measurements of brain-wave activity confirmed the behavioral studies, proving a one-to-one correspondence between open eyes and wakeful brains. Can humans sleep like this? Unfortunately not, although Rattenborg says that some sleep disorders, like sleepwalking, may have their roots in unihemispheric sleep.EDITED BY ELLEN LICKINGReturn to top
Fluorescent Lights Get a Green Glow
FLUORESCENT LIGHTS ARE CHEAP, EFFICIENT, AND BRIGHT. But because they contain mercury, a highly toxic gas that damages the environment, they are far from perfect. Now, in this week's Science, researchers from Utrecht University in the Netherlands report an important advance in the quest for a "greener" fluorescent light.
Turning on a fluorescent lamp involves more than flipping a switch. It requires both particle physics and chemistry to do the job. When electricity passes through the mercury-filled tube, the liquid vaporizes and emits ultraviolet (UV) light particles called photons. Next, phosphors, crystals on the inner walls of the tube, absorb the UV light and re-emit the energy to make white light.
Replacing the mercury inside the tube with an inert gas like xenon would bypass the current environmental hazards, but the stumbling block has been the phosphors. The current crystals can't efficiently transfer the energy from the xenon-produced photons to make visible light. So the Dutch researchers, led by Andries Meijerink, searched for new phosphors and discovered two that work together to emit red light.
Because plain red light isn't useful in most commercial settings, Meijerink is currently hunting for phosphors that emit green and blue photons, which can be used in combination with the red photons to create white light. Meantime, Royal Philips is helping the Dutch group optimize the new phosphors for future commercial applications.EDITED BY ELLEN LICKINGReturn to top
AIDS Drugs May Rehabilitate the Immune System
SOME POWERFUL DRUGS ARE KEEPING THE AIDS VIRUS UNDER CONTROL in thousands of patients. And the fact that certain immune cells, called CD4 cells, increase in number after drug treatment suggests that patients' immune systems have at least partly recovered. But doctors worry that recovering immune systems might still be vulnerable to diseases like Pneumocystis carinii pneumonia (PCP), one of the many so-called opportunistic infections that strike AIDS victims. That's why physicians continue to recommend taking medicine to prevent these infections.
Researchers in Madrid and Barcelona decided to find out what happens when patients call a halt to preventive treatment. The researchers recruited 332 people infected by the HIV virus whose CD4 cell counts had gone up after taking anti-AIDS drugs. Roughly half of them continued to take drugs to prevent PCP. The other half went without.
The results, reported on Feb. 4 at the 6th Conference on Retroviruses & Opportunistic Infections in Chicago, were dramatic. Although AIDS patients are extremely susceptible to PCP infections, none of the study participants came down with the disease during the six-month investigation.
Experts were encouraged by the findings. Dr. Constance A. Benson, the vice-chairman of the retroviral meeting's scientific program committee, says that there is now a growing body of evidence suggesting "that with potent anti-retroviral therapy, people can recover some immune function, which can protect them against opportunistic disease."EDITED BY ELLEN LICKINGReturn to top