| A SINGLE therapeutic dose of radiation
can trigger dangerous amounts of bone loss, leaving bones hollowed out
and frail - at least in mice. The finding has implications for cancer radiation
therapies, but reports that the findings bode ill for astronauts on long
space missions may be overstating the danger.
Ted Bateman and his colleagues at Clemson University in South Carolina analysed the bones of mice exposed to four kinds of radiation: gamma rays, protons, and high-speed carbon and iron nuclei.
|They created 3D computer scans of the spongy interior of the bones,
and used these to calculate how much bone the irradiated mice lost relative
to a control group.
In each case, the irradiated mice lost between 29 and 39 per cent of the bones' spongy interior, which acts as a latticework to strengthen bones. "We were surprised at how large the difference in bone mass was," says Bateman.
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Submitted on September 2, 2005
Accepted on May 19, 2006
A Murine Model for Bone Loss from Therapeutic and Space-Relevant Sources of Radiation
Sarah A Hamilton1, Michael James Pecaut2, Daila S. Gridley3, Neil D Travis1, Eric R. Bandstra1, Jeff S. Willey1, Gregory Nelson3, and Ted A. Bateman1*
1 Department of Bioengineering, Clemson University, Clemson, South Carolina,
2 Department of Radiaition Medicine, Loma Linda University, Loma Linda, California, United States
3 Department of Radiation Medicine, Loma Linda University and Medical Center, Loma Linda, California, United States
* To whom correspondence should be addressed. E-mail: email@example.com
|Cancer patients receiving radiation therapy are exposed to photon (gamma/x-ray), electron and less commonly, proton radiation. Similarly, astronauts on exploratory missions will be exposed to extended periods of lower-dose radiation from multiple sources and of multiple types, including heavy ions. Therapeutic doses of radiation have been shown to have deleterious consequences on bone health, occasionally causing osteoradionecrosis and spontaneous fractures. However, no animal model exists to study the cause of radiation-induced osteoporosis. Additionally, the effect of lower doses of ionizing radiation, including heavy ions, on general bone quality has not been investigated. This study presents data developing a murine model for radiation-induced bone loss. Female C57BL/6 mice were exposed to gamma, proton, carbon, or iron radiation at 2-Gray doses, representing both a clinical treatment fraction and spaceflight exposure for an exploratory mission.||Mice were euthanized 110 days after irradiation. The proximal tibiae and femur diaphyses were analyzed using microcomputed tomography. Results demonstrate profound changes in trabecular architecture. Significant losses in trabecular bone volume fraction were observed for all radiation species: gamma, (-29%), proton, (-35%), carbon (-39%), and iron (-34%). Trabecular connectivity density, thickness, spacing, and number were also affected. These data have clear implications for clinical radiotherapy, in that bone loss in an animal model has been demonstrated at low doses. Additionally, these data suggest that space radiation has the potential to exacerbate the bone loss caused by microgravity, though lower doses and dose rates need to be studied.|
Ted Bateman, (864) 656-0180 lab, (720) 810-3626 cell
Susan Polowczuk, (864) 656-2063
Christine Guilfoy, American Physiological Society, (301) 634-7253
CLEMSON SPACE RESEARCH EXPLORES BONE LOSS
|CLEMSON — Astronauts who travel in space are at risk for bone loss in much the same way that cancer patients who receive radiation therapy are, and both groups are more likely to develop fractures than the general population.|| To better understand the causes, Clemson researchers
have developed the first model to study the rate of bone loss in those
two groups. Their results are published in the Journal of Applied Physiology.
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