Marc D. Grynpas

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Our purpose here is to test the hypothesis that Randall's plaques, calcium phosphate deposits in kidneys of patients with calcium renal stones, arise in unique anatomical regions of the kidney, their formation conditioned by specific stone-forming pathophysiologies. To test this hypothesis, we performed intraoperative biopsies of plaques in kidneys of(More)
The inbred strains of mice C57BL/6J (B6) and C3H/HeJ (C3H) have very different femoral peak bone densities and may serve as models for studying the genetic regulation of bone mass. Our objective was to further define the bone biomechanics and microstructure of these two inbred strains. Microarchitecture of the proximal femur, femoral midshaft, and lumbar(More)
Little is known regarding the mechanisms that govern the structural organization of cancellous bone. In this study, we compare the nature of the collagen in vertebral cancellous bone with the structural organization of its trabecular network. Cylindrical specimens of cancellous bone from vertebrae were obtained from nine autopsy subjects (ages 46-88). In(More)
Tissue engineering of articular cartilage is a promising alternative for cartilage repair. However, it has been difficult to develop tissue in vitro that mimicks native cartilage. Cartilaginous tissue formed in vitro does not accumulate enough extracellular matrix, is deficient in collagen, and possesses only a fraction of the mechanical properties of(More)
This cross-sectional study investigates metabolic bone disease and the relationship between age and bone mineral density (BMD) in males and females of a large, well-documented skeletal population of free-ranging rhesus monkeys (Macaca mulatta), from the Caribbean Primate Research Center Museum collection from Cayo Santiago, Puerto Rico. The sample consists(More)
The cellular and molecular mechanisms that underlie age-dependent osteoporosis, the most common disease in the Western Hemisphere, are poorly understood in part due to the lack of appropriate animal models in which to study disease progression. Here, we present a model that shows many similarities to the human disease. Sca-1, well known for its expression(More)
Strontium (Sr) has been shown to increase bone mass when given at low doses. In this study, the diets of rats containing 0.50% calcium were supplemented with Sr (0.19 and 0.40% of SrCl2 orally) for periods of four and eight weeks. Long bones and vertebrae were studied by density fractionation and each fraction was analyzed chemically. X-ray diffraction was(More)
Porous structures were formed by gravity sintering calcium polyphosphate (CPP) particles of either 106-150 or 150-250 microm size to form samples with 30-45 vol% porosity with pore sizes in the range of 100 microm (40-140 microm). Tensile strength of the samples assessed by diametral compression testing indicated relatively high values for porous ceramics(More)
Fluoride is known to have biological effects on bone cells as well as physicochemical effects on bone crystals. This review concentrates on the latter. Fluoride increases the stability of the apatite lattice and decreases the solubility of the apatite crystals. In bone mineral, this ion has been shown to affect bone crystal structure by increasing(More)
Bone mineralization changes with age and disease. The distribution of mineral particles in a given bone (mineralization profile) has been studied using density fractionation as well as microradiography and electron backscattering imaging. The biological determinant of mineralization is the rate of turnover. During rapid growth and periods of high(More)