Bone change with age and disease, manifested in modification of mineral content, density, and structure, are evident in loss of mechanical properties which can be detected by ultrasonics. The Less-Davidson hypothesis asserts, on the basis of the stereo-chemical structure of collagen, that bone matrix stiffens as a consequence of the mineralization process. Furthermore, a linear dependence between bone density and sonic velocity has been found for normal adult bone. Defective bone collagen is known to be associated with weak bone and the sonic velocity must be significantly less than for normal bone. Elastic properties, dimensional changes with water content, density, and composition of osteoporotic, osteodystrophic, and osteomalacic bone will be compared to determine if there are differences that can be attributed to defects in the collagen intermolecular structure. Bones of animals having known pathologies induced under controlled conditions will be examined by methods including ultrasonic microscopy to relate cross-linking collagen defects to decreases in density and ultrasonic velocity. Insight and understanding of the fundamental processes controlling the elastic properties of bone at the molecular and ultrastructural level is sought. It will contribute to the theory of the properties of bone and how it is affected by age and pathologies like osteoporosis, renal osteodystrophy, and Paget's disease.

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National Institute on Aging (NIA)
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Diagnostic Radiology Study Section (RNM)
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Forsyth Institute
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Lees, S; Hanson, D B; Page, E A (1996) Some acoustical properties of the otic bones of a fin whale. J Acoust Soc Am 99:2421-7
Prostak, K S; Lees, S (1996) Visualization of crystal-matrix structure. In situ demineralization of mineralized turkey leg tendon and bone. Calcif Tissue Int 59:474-9
Lees, S; Prostak, K S; Ingle, V K et al. (1994) The loci of mineral in turkey leg tendon as seen by atomic force microscope and electron microscopy. Calcif Tissue Int 55:180-9
Lees, S; Hanson, D; Page, E et al. (1994) Comparison of dosage-dependent effects of beta-aminopropionitrile, sodium fluoride, and hydrocortisone on selected physical properties of cortical bone. J Bone Miner Res 9:1377-89
Tao, N J; Lindsay, S M; Lees, S (1992) Measuring the microelastic properties of biological material. Biophys J 63:1165-9
Lees, S; Klopholz, D Z (1992) Sonic velocity and attenuation in wet compact cow femur for the frequency range 5 to 100 MHz. Ultrasound Med Biol 18:303-8
Lees, S; Hanson, D B (1992) Effect of fluoride dosage on bone density, sonic velocity, and longitudinal modulus of rabbit femurs. Calcif Tissue Int 50:88-92
Lees, S; Eyre, D R; Barnard, S M (1990) BAPN dose dependence of mature crosslinking in bone matrix collagen of rabbit compact bone: corresponding variation of sonic velocity and equatorial diffraction spacing. Connect Tissue Res 24:95-105
Lees, S; Prostak, K (1988) The locus of mineral crystallites in bone. Connect Tissue Res 18:41-54
Lees, S; Barnard, S M; Churchill, D (1987) The variation of sonic plesio-velocity in dose dependent lathyritic rabbit femurs. Ultrasound Med Biol 13:19-24

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