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A Leap in Drug Research from Frogs


Scientists for some 50 years have been intrigued by the peculiar chemicals on the skins of tropical frogs--a sort of venom secreted to ward off predators. Only since the mid-1990s, though, have the latest high-precision analytical instruments begun to reveal some of the medical potential that could lie hidden in frog secretions.

In Ireland, at the University of Ulster's Coleraine campus, a research team led by biotechnology professor Chris Shaw has observed that peptides from the giant Mexican leaf frog can reduce the blood pressure of lab animals by 50%. And those from Australian tree frogs have spectacular antibiotic properties, killing bacteria by rupturing their cell walls. Shaw claims that bacteria cannot develop resistance to such peptides.

Given these promising results, the university has coughed up money for new equipment, including a chemical-synthesis facility that can produce sample peptides for screening by drug companies. Launching a drug startup at Ulster's incubator park is now under consideration. Shaw also wants to expand frog-collection efforts in Central and South America. Most of the fieldwork so far has been done in the rain forests of southern China, he says, adding: "We leave Monday next [Oct. 1] on another expedition to China." Software networks that mimic the brain's circuitry, known as neural nets, perform a wide range of jobs, from diagnosing diseases to uncovering correlations hidden in massive databases. While still primitive compared with a real brain, these networks may soon get much smarter, thanks to work by Philip Husbands and other artificial intelligence researchers at Britain's University of Sussex.

The team is building on recent discoveries about how the brain actually works. It's not just a matter of electrical impulses exchanged among neurons. Messenger molecules of nitric oxide also play a key role in learning and memory. The nitric oxide doesn't necessarily travel along the brain's usual pathways, but diffuses through the brain like a gas, affecting remote neurons that have no direct physical link to the sending neuron. The Sussex team is building nets that emulate both brain mechanisms. One of them is a silicon brain for an android robot, which learned to walk and recognize objects faster than the team's other androids. When Edward S. Kolesar heard in 1999 that Motorola planned to replace cell-phone batteries with a miniature fuel cell that would generate electricity from a chemical reaction fueled by alcohol, the Texas Christian University engineer got to wondering. Could he adapt a fuel cell to detect drunken drivers by generating an electrical signal when the alcohol vapors on a driver's breath exceeded a certain level? He succeeded--and his fuel-cell sensor not only detects when a driver has had too much to drink but also uses the electricity to send a radio alert to nearby cop cars.

The sensor can be hidden behind the dashboard. It samples the interior air continuously but generates electricity only when alcohol fumes are present--and broadcasts a warning only when they exceed a preset threshold. Kolesar says his handmade unit costs $100, "so the price is going to go way down for mass-produced systems."

A van equipped with the gadget is being tested at the University of Texas at Arlington. One worry is that it might be triggered by alcohol from after-shave or hairspray, but that hasn't happened so far. If all goes well, Kolesar figures the device should be ready for Detroit within a year. Eventually, he hopes, his brainchild will show up "in every car, every train, every bus, and every truck," and help end the highway slaughter by drunk drivers. -- Ceramics generally snap like glass if bent--but not the concoction developed by researcher Kim Byung-Nam and his team at the National Institute for Materials Science in Tsukuba, Japan. They whipped up a mixture of zirconium, magnesium aluminate, and alumina that offers unusual ductility: It can bend and stretch. At high temperatures, it can be molded or stamped much like a metal, opening the door to replacing certain metal parts with lighter, stronger ceramics. The work is reported in the Sept. 20 Nature magazine.

-- Scientists discovered 11 years ago that silicon surfaces riddled with tiny holes can emit light. Holey silicon seemed set to make it big in light-emitting diodes (LEDs), displacing costly semiconductors such as gallium nitride. So why are porous-silicon LEDs still just a lab curiosity? Because silicon's optical properties soon fade away. Now, researchers at Purdue University, led by chemist Jullian M. Buriak, have found a way to "pickle" holey silicon--by zapping it with intense white light in the presence of gaseous compounds containing carbon and hydrogen. This creates a thin coating that preserves the optical properties.

-- Sometimes the brain produces too much of the chemical dopamine, a stuation associated with Parkinson's disease. In the Sept. 28 issue of Science, researchers at Boston University Medical Center say common compounds used to treat depression may mitigate the problem--and slow down the disease.


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