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pubmed:abstractText |
During the 51 G franco-american mission in weightlessness, calcium metabolism and hormonal regulation were analyzed in two astronauts (a male, a female) before (30,7 and 4 days) and after (0,2 and 5 days) the 7-day spaceflight. Calcium, phosphate, alkaline phosphatase, GLA protein, 25 hydro-vitamin D, 1-25 dihydroxyvitamin D, parathyroid hormone, 24 h urinary calcium, total, dialysable and nondialysable hydroxyproline and glycosaminoglycans (GAG) were measured in blood and urine. Only urinary parameters are increased after space flight. Blood parameters, in particular hormone measurements, are unchanged. The data indicate stimulation of resorptive activity which could result in bone matrix atrophy and demineralisation. On the contrary, no bone formation impairment is noted since alkaline phosphatase and GLA protein are unchanged. These changes are not dependent on hormonal variations. They could only reflect the mechanical bone adaptation to weightlessness.
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