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M D Grynpas

Publications and source records attributed to M D Grynpas.

94 records · Page 6Linked to original sources
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The distribution of soluble, mineral-bound, and matrix-bound proteins in osteoporotic and normal bones.

Very little is known about the composition of noncollagenous protein (NCP) in osteoporotic bone. We have obtained osteoporotic (OP) cancellous bone samples from 2-4 cm below the surface of human femoral heads and compared the protein profiles to age-matched (old controls, OC), as well as young autopsy controls (YC). The proteins were analyzed using a serial extraction method which liberates proteins from distinct pools; first, proteins were extracted in 4.0 M GuHCl (G1), followed by the extraction of mineral-bound protein with 0.5 M EDTA (E), and finally the protein previously masked by the mineral was released by a second 4.0 M GuHCl extraction (G2). The tissue residue was digested with bacterial collagenase liberating proteins bound to the collagenous matrix. Uniform bone preparations of finely ground bone powder were used for our study. The protein content of the four groups was determined together with the protein distribution using amino acid analysis and gel-electrophoresis. Our data indicate that the noncollagenous protein content is considerably reduced in osteoporotic bone when compared with age-matched or young controls, whereas the collagen content is unaffected. When bone proteins were investigated using gel-electrophoresis we found a similar distribution of proteins in the G1 and E fractions of all three groups, but the osteoporotic bone samples, using densitometric analysis of the gels, showed quantitative differences in a number of the proteins. The greatest differences were observed in the G2 extract, where the NCP of osteoporotic bone was limited to a few low-molecular-weight bands when compared with the OCs or YCs.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
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Effect of long-term ovariectomy on bone mechanical properties in young female cynomolgus monkeys.

Feral adult female cynomolgus monkeys were divided into two groups: normal controls and ovariectomized. Tibiae and trabecular bones from the femoral head, from each group, were tested using a materials testing machine. The bending stiffness of the tibiae was measured by nondestructive three-point bending tests and their maximum torque capacity by destructive torsion tests. The compressive strength of the trabecular bones was measured by compression tests. Ovariectomy caused significant decreases in elastic modulus of the tibiae (p < 0.008), measured by three-point bending tests, and in shear modulus (p < 0.015), failure shear stress (p < 0.01), and failure torque (p < 0.001) of the tibiae, measured by torsion tests. It caused a significant decrease in cortical bone density (p < 0.005), but no significant changes in tibial cross-sectional area and in cortical shaft external and internal diameters. The differences in elastic modulus, maximum compressive strength, and density of femoral trabecular bone samples between the two groups were not significant.

Animals↗