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| Vol. 20, No. 21 |
| November 15, 1998 |
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Shuttle Astronauts to Participate in MRI Study by KATHY MAJOR Baylor College of Medicine Four astronauts, including John Glenn, will help scientists learn more about bone and muscle loss in space.
STS-95 mission commander Curt Brown, pilot Steve Lindsey, mission specialist Steve Robinson and payload specialist Glenn are participants in the latest study. The mission returned to Earth on Nov. 7 after a nine-day flight on board the space shuttle Discovery. "Understanding bone changes related to space travel and learning how to prevent them might provide solutions for similar conditions on Earth like osteoporosis," says Dr. Adrian LeBlanc, a medical physicist at Baylor College of Medicine and The Methodist Hospital. In space, astronauts lose about 1 to 1.5 percent of their bone mass each month. Although the risk is minimal on shuttle flights, maintaining bone strength will be crucial for interplanetary exploration and for a safe return to Earth after long missions. "The spine, hip and pelvis lose bone at a higher rate than other bone regions," Dr. LeBlanc says. "These same bones are most affected in postmenopausal osteoporosis and aging." Dr. LeBlanc has been gathering data from cosmonauts and astronauts on Mir and space shuttles for several years. To document changes, Dr. LeBlanc uses bone mineral density measurements, magnetic resonance imaging (MRI) and spectroscopy. The current measurements for flight STS-95 focus on bone marrow, muscles and intervertebral disks. Dr. LeBlanc's group is sharing leg muscle measurements with researchers studying protein turnover in space. The astronauts had two preflight measurements to establish a baseline status and will return for measurements seven times during the first six months after landing. "Even on short missions, we have determined that changes in the bone metabolism have begun," says Dr. LeBlanc, who collaborates on ground-based bed rest studies with the National Space Biomedical Research Institute. "In space, expansion also occurs in the intervertebral disks. We want to measure the amount of change and how long it takes to return to preflight conditions." In previous astronaut groups, after a 17-day flight, bone marrow activity was elevated for several weeks to months after the flight before returning to the preflight baseline. "We think this activity is related to the stimulation of bone formation once the astronauts return to gravity," Dr. LeBlanc says. "Bone formation rate decreases as we age, so we might see some differences in response among the astronauts." Data collected from astronauts might one day lead to potential treatments for bone and muscle loss in aging individuals as well as astronauts. Dr. LeBlanc hopes to do related research with the National Institute on Aging.
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