title: Effects of chair restraint on the strength of the tibia in rhesus monkeys.
abstract: To determine the effects of the relative inactivity and unloading on the strength of the tibias of monkeys, Macaca mulatta, we used a non-invasive test to measure bending stiffness, or EI (Nm2), a mechanical property. The technique was validated by comparisons of in vivo measurements with standard measures of EI in the same bones post-mortem (r2 = 0.95, P < 0.0001). Inter-test precision was 4.28+/-1.4%. Normative data in 24 monkeys, 3.0+/-0.7 years and 3.6+/-0.6 kg, revealed EI to be 16% higher in the right than left tibia (4.4+/-1.6 vs. 3.7+/-1.6 Nm2, P < 0.05). Five monkeys, restrained in chairs for 14 days, showed decreases in EI. There were no changes in EI in two chaired monkeys that lost weight during a 2-week space flight. The factors that account for both the decreases in bone mechanical properties after chair restraint at 1 g and lack of change after microgravity remain to be identified. Metabolic factors associated with body weight changes are suggested by our results.
authors: Life Sciences Division NASA Ames Research Center, Moffett Field, CA 94035-1000, USA.
authors: T M
authors: TM
authors: Hutchinson
authors: A V
authors: AV
authors: Bakulin
authors: A S
authors: AS
authors: Rakhmanov
authors: R B
authors: RB
authors: Martin
authors: C R
authors: CR
authors: Steele
authors: S B
authors: SB
authors: Arnaud
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001835:Body Weight; D005260:Female; D008253:Macaca mulatta / Q000502:physiology*; D008297:Male; D015203:Reproducibility of Results; D012149:Restraint, Physical; D012680:Sensitivity and Specificity; D013026:Space Flight; D013977:Tibia / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology; D018474:Weightlessness Simulation