On the wing

A three-dimensional skeletal model of a pigeon in flight has been created by Brown University researchers who are working to develop a new, true 3-D imaging technology. A technique developed by associate professor Stephen Gatesy and student David Baier uses animation software to align 3-D CT bone models with 2-D X-ray movies of birds flying in a wind tunnel. To see videos, visit brown.edu/ctx/ and brown.edu/Departments/EEB/brainerd_lab/ctx/movie1.php.

Exercise doesn't hurt knees; doesn't help either

ARTHRITIS
Moderate exercise neither increases nor decreases risk of knee osteoarthritis, a new study finds. In knee osteoarthritis, the cartilage at the joint wears down, causing bones to rub against each other leading to pain, swelling, and stiffness. Some past studies had suggested that exercise can reduce the risk of developing this form of arthritis by making knee-joint cartilage stronger, whereas other studies suggested that when older people exercise they can injure their knee joints and actually increase osteoarthritis risk, especially if they are overweight. But a recent study led by Dr. David Felson at the Boston University School of Medicine suggests that moderate exercise has no effect on the risk of developing knee osteoarthritis. For the study, Felson and colleagues took knee X-rays of 1,279 people, ranging in age from their 20s to their 80s and also asked them to report knee pain, stiffness, and level of physical activity. After nine years, the participants were reassessed. Researchers found that moderate exercise had no bearing on the risk of developing knee osteoarthritis.

BOTTOM LINE: Older people -- even those who are overweight -- will not damage their knees by getting moderate exercise. "This is a good thing because exercise is important for older people," Felson said.

CAUTIONS: The study is the first to show that exercise does not affect knee osteoarthritis risk. More research is needed to confirm these findings.

WHAT'S NEXT: Felson hopes someone will investigate how more vigorous exercise affects knee osteoarthritis risk.

WHERE TO FIND IT: Arthritis Care & Research, February.

SENA DESAI GOPAL

NEUROLOGY

For first time, researchers explain how LSD works

Seventy years after it was first synthesized and four decades after it became a trademark of American counterculture, a team of scientists believes it has figured out, for the first time, how LSD and similar hallucinogens produce their psychedelic effects. With the discovery, the researchers hope to better understand how current psychiatric drugs work and to develop more effective drugs for illnesses like schizophrenia. In a series of tests on mice, the scientists compared the effects of LSD with a closely related but non-hallucinogenic chemical called lisuride. Both chemicals have been shown to target a specific class of serotonin receptor known as 2AR, though it had not been understood why the two produce different effects. The team found that the substances activate the 2AR receptors in distinct ways, which leads to different signaling responses inside cells. "If this [distinct effect on a receptor] is the basis for a drug to have its effect, then the approach taken in this study could help us identify more effective drugs for neurological and psychiatric disorders," said Dr. Stuart Sealfon of Mount Sinai School of Medicine, one of the study's authors.

BOTTOM LINE: Hallucinogens appear to activate a specific class of serotonin receptor in ways distinct from chemically similar nonhallucinogens, explaining the substances' very different effects. This principle might help researchers understand how current psychiatric drugs work and develop more effective drugs for disorders such as schizophrenia.

CAUTIONS: Extrapolating findings from mice to humans might be risky. "We have to be careful in how we use this information," Sealfon said. "Mouse models tend to be useful when applied to humans, but they're never perfect."

WHAT'S NEXT: The team will try to use the current findings to better understand what underlies the beneficial and harmful effects of certain psychoactive drugs.

WHERE TO FIND IT: Neuron, Feb. 1.

AMI ALBERNAZ