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Effect of a growth hormone treatment on bone orthotropic elasticity in dwarf ratsA refinement of the current ultrasonic elasticity technique was used to measure the orthotropic elastic properties of rat cortical bone as well as to quantify changes in elastic properties, density, and porosity of the dwarf rat cortex after a treatment with recombinant human growth hormone (rhGH). The ultrasonic elasticity technique was refined via optimized signal management of high-frequency wave propagation through cubic cortical specimens. Twenty dwarf rats (37 days old) were randomly assigned to two groups (10 rats each). The dwarf rat model (5-10% of normal GH) was given subcutaneous injections of either rhGH or saline over a 14-day treatment period. Density was measured using Archimedes technique. Porosity and other microstructural characteristics were also explored via scanning electron microscopy and image analysis. Statistical tests verified significant decreases in cortical orthotropic Young's (-26.7%) and shear (-16.7%) moduli and density (-2.42%) concomitant with an increase in porosity (+125%) after rhGH treatments to the dwarf model (p < 0.05). A change in material symmetry from orthotropy toward planar isotropy within the radial-circumferential plane after GH treatments was also noted. These results demonstrate some alteration in bone properties at this time interval. Structural implications of these changes throughout physiological loading regimens should be explored.
Document ID
20040173054
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Kohles, S. S.
(University of Wisconsin Madison, United States)
Martinez, D. A.
Bowers, J. R.
Vailas, A. C.
Vanderby, R. Jr
Date Acquired
August 22, 2013
Publication Date
January 1, 1997
Publication Information
Publication: Annals of biomedical engineering
Volume: 25
Issue: 1
ISSN: 0090-6964
Subject Category
Aerospace Medicine
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Musculoskeletal
NASA Discipline Number 26-10
Non-NASA Center
NASA Program Space Physiology and Countermeasures

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