Developments to Watch
I Get No Kick from...Nicotine
The addiction to nicotine is so intense that the American Psychiatric Assn. estimates that only 10% to 30% of those who resolve to quit make it past the first six months. But what if a simple vaccine could prevent a person from experiencing nicotine's pleasurable kick? Nabi, a pharmaceutical company based in Boca Raton, Fla., is testing this controversial idea by provoking an immune reaction to nicotine in the blood. Preliminary findings in rats have been so encouraging that the company plans to begin testing its vaccine, called NicVax, in humans later this year.
Under normal circumstances, the body would never mount an immune response against a small molecule such as nicotine. Company researchers overcame this hurdle by linking nicotine to a "carrier" protein that is easily recognized by the body's defense system. The goal: to unleash powerful antibodies that will scarf up circulating nicotine molecules before they can bind to receptors in the brain that trigger the pleasurable--and addictive--response.
The approach seems to work. When rats inoculated with NicVax are exposed to two to three cigarettes' worth of nicotine, the amount of nicotine that reaches their brains is reduced by 65%. That's enough to prevent the physical and behavioral responses normally sparked by the chemical, including skyrocketing blood pressure and increased motor activity.
Because it takes time to build up antibodies to the vaccine, NicVax won't immediately reduce cravings for nicotine. But in combination with current medications, it might purge the urge to puff.
By Ellen Licking
How to Pack a Mighty Punch on a Tiny Chip
Nanotubes--cylinders of carbon roughly one-billionth of a meter in diameter--may one day serve as transistors on computer chips. Five hundred times smaller than today's transistors, they could be the basis for fast chips, but only if engineers can devise an inexpensive approach for densely packing them onto silicon wafers. Researchers at IBM think they have such a method.
It's a challenge because nanotubes naturally occur in two forms: semiconducting tubes and metallic ones. When nanotubes are deposited onto a silicon substrate, the result is a dense tangle of both. To build devices, chipmakers need to eliminate the metallic tubes and manipulate only the semiconducting ones.
In the Apr. 27 issue of Science, a team from IBM Research led by senior scientist Phaedon Avouris describes one promising approach. First, the researchers disperse a tangle of nanotubes on silicon and fabricate electrodes on top of them. These electrodes are employed to switch off all the semiconducting tubes in the pile, so that they can't carry a current. Researchers then apply a voltage to selectively shatter the metallic tubes.
With this technique, researchers can also remove concentric layers of nanotubes that are rolled up inside one another (image). By sculpting such rolls of tubes, scientists can produce transistors with the properties they desire.
By Ellen Licking
Learning from the Bees to Get ZZZs
There may soon be hope for the sleep-deprived or jet-lagged, deduced from the mysterious habits of honeybees. In the Apr. 26 issue of Nature, entomologists at the University of Illinois at Urbana-Champaign report that honeybees automatically reset their internal body clocks in times of stress. Understanding exactly what happens at the cellular level could point the way to new therapies for human insomnia and other disorders.
In the typical hive, larvae are nursed round the clock by young bees, while older bees forage for food. Foraging requires a well-developed internal clock, because the bees depend on the sun to navigate toward pollen-containing flowers. The researchers observed that if the population of nurse bees suddenly plummets, forager bees immediately take over nursing responsibilities--and reset their internal clocks in the process.
The researchers don't know how the bees retune their body clocks. They believe a complicated network of genes--many of them shared by bees and humans--is probably involved.
By Ellen Licking
Innovations
-- Ultrasound, a mainstay of medical imaging, may soon have another use: removing toxic chemicals such as the gasoline-additive MTBE from groundwater. It's well known that sound waves of specific frequencies can be used to break apart harmful organic molecules. The challenge has been making the degradation process more efficient.
Civil engineer Inez Hua of Purdue University believes she may have partly solved this dilemma. In the Apr. 19 issue of The Journal of Physical Chemistry A, she demonstrates that it is possible to break down 1,4-dioxane, an MTBE-like molecule, into innocuous byproducts by blasting polluted water for two hours with sound waves at a frequency of 358 kilohertz.
-- In his 1999 book The River: A Journey to the Source of HIV and AIDS, journalist Edward Hooper posited that the modern-day AIDS epidemic arose when oral polio vaccine samples made from contaminated chimp cells were given to people in the Belgian Congo. The book sparked heated debates at scientific meetings as well as in Internet chat rooms. But new data should finally quell the furor.
Four independent studies, published in the Apr. 26 issue of Nature and the Apr. 27 issue of Science, categorically repudiate the link between the oral polio vaccine and the rise of AIDS. Using a sensitive laboratory technique called polymerase chain reaction to amplify DNA in more than 20 remaining samples of the vaccine, researchers at the different institutions were unable to find traces of either HIV-1, the strain that causes AIDS; SIV, the monkey version of HIV; or DNA indicating that chimp cells were used to prepare the vaccine.
By Ellen Licking
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Copyright 2001 , by The McGraw-Hill Companies Inc. All rights reserved.
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