Subtle shake-up in bone-loss research.

Recent research in the prevention of bone loss during weightlessness is described. Scientists are studying the effects of vibration on bone loss in laboratory animals and humans. Research is focused on determining how bone formation is triggered, the effects of stimulation of the stress response in bones, and the mechanisms behind the effects. Clinton Rubin at the State University of New York at Stony Brook is experimenting with 90 Hz vibration frequencies in rats. Other researchers are studying the effects of vibration plates in the treatment of osteoporosis in postmenopausal women and in children with low bone density. Tests among astronauts have been proposed, but none are scheduled.