Review of NASA's Biomedical Research Program (2000) / Chapter Skim
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3 Bone Physiology
3 Bone Physiology
Pages 19-25
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From page 19... ...
a comprehensive description of the phenomenon in humans, including the development of a careful record of skeletal changes occurring during microgravity and postflight and the time course and rate of these changes; (b) a determination of whether changes produced by microgravity in animal bones mimic human changes and whether they have a similar mechanistic basis, and a comparison of pertinent animal models in spaceflight to ground-based models (such as hindlimb unloading)
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From page 20... ...
Recently initiated studies involve the application of mechanical loads with complete control and characterization of cycle number, rate, peak intensity, and rate of strain, in order to document changes in osteoblast regulatory genes and gene products. In accord with Strategy report recommendations, one of the NSBRI programs explores the effects of a variety of pharmacologic agonists known to interact with the estradiol, vitamin D, or calcium-sensing receptors on mature bone cells and their precursors.
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From page 21... ...
Human Studies For human studies, the Strategy report recommended the development of a comprehensive description of microgravity-induced bone loss, using state-of-the art noninvasive methods entailing a careful record of skeletal changes postflight for each astronaut. It recommended initiation of a comprehensive database for the purposes of correlating skeletal changes with age, gender, muscle changes, diet, and genetic factors.
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From page 22... ...
In addition, a series of mechanistic studies were recommended to give insight into the relative contributions of bone resorption and formation to the skeletal changes of microgravity. However, the paucity of flight opportunities currently requires the bone program to be entirely ground based, and except for continuation of a calcium turnover project, no work currently addresses these recommendations.
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From page 23... ...
An additional approach could involve administration of newly developed drugs and biological agents that regulate osteoblast or osteoclast function as a countermeasure against bone loss. Despite the fact that countermeasure studies are in progress at ARC, ,ISC, and NSBRI laboratories, there is little evidence of coordination of these programs or, for that matter, of a system-wide coordinated process for testing and validating potential skeletal countermeasures as recommended by the Strategy report.
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From page 24... ...
Application of contemporary molecular biology techniques to mechanically loaded cells, the load-sensing shoe insert, new computer algorithms for resolving bone geometry from DXA scans, and the miniature bone densitometer described above are examples of such advanced technology. In accord with Strategy report recommendations and as part of an NSBRI Technology Development Program, an innovative miniature bone densitometer is currently under development that will theoretically be sufficiently portable for skeletal monitoring to be accomplished during the course of an extended mission.
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From page 25... ...
With respect to countermeasure development, one identified problem is the apparent lack of a formal mechanism to bring potential countermeasures to formal assessment, as well as an apparently haphazard and unfocused epidemiology and monitoring component that fails to take advantage of unique and potentially valuable research data. BIBLIOGRAPHY National Aeronautics and Space Administration (NASA)
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