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  • NDE  (21)
  • Bone  (16)
  • Springer  (37)
  • American Association of Petroleum Geologists (AAPG)
  • Nature Publishing Group
  • 1980-1984  (37)
  • 1945-1949
Collection
Publisher
  • Springer  (37)
  • American Association of Petroleum Geologists (AAPG)
  • Nature Publishing Group
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Year
  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 31 (1980), S. 215-223 
    ISSN: 1432-0827
    Keywords: Bone ; 1,25(OH)2D3 ; 25OHD3 ; Histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Rachitic rats, maintained on diets with low or normal P contents, were given daily intraperitoneal doses of 1,25(OH)2D3 or 25OHD3 at levels of 100 or 200 ng. Plasma chemistry was measured and the ash content and histological appearance of the bones investigated. Using labeled material it was shown that the dosing levels of 1,25(OH)2D3 employed ensured a higher than normal plasma concentration of that metabolite over the period between doses. 1,25(OH)2D3 was not as effective as 25OHD3 in raising bone ash or reducing the amount of osteoid. The difference between the effects of the metabolites was evident at both dietary P levels, but more marked at the higher P level. In contrast, the metabolites reduced the width of the epiphyseal plate to an approximately similar degree, and this is possibly the reason why there are discrepancies between previous reports of the effectiveness of 1,25(OH)2D3 compared with 25OHD3 or vitamin D3. Dosing with 1,25(OH)2D3 failed to maintain a constant plasma Pi value over the period between doses in animals fed the low P diet.
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  • 12
    ISSN: 1432-0827
    Keywords: Bone ; Mineral ; Crystallinity ; Maturation ; Age
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The crystallinity of bone mineral at different stages of maturation has been measured by quantitative X-ray diffraction methods. Crystallinity measurements were made on tibial middiaphyses from 17-day embryonic chicks, newlyformed periosteal bone from embryonic chicks, and density-fractionated bone from post-hatch chickens from 5 weeks to 2 years of age. For a given animal age and degree of mineralization, crystallinity increases with animal age, indicating that changes in bone mineral occur even after mineralization is complete or nearly complete.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 36 (1984), S. S118 
    ISSN: 1432-0827
    Keywords: Bone ; Strain ; Remodeling ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary For bone to remodel adaptively, the cells responsible should follow some algorithm. Nine different loading situations and structures are discussed. It seems that either algorithm must be extremely complex, or cells in different structures must follow different algorithms.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 33 (1981), S. 499-504 
    ISSN: 1432-0827
    Keywords: Bone ; Collagen ; Density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The density of a bovine cortical bone matrix sample was found in water, several ethanol-water solutions, and in the dried state. Previously the density of the same mineralized bone was found fresh and when desiccated. The volume in each state was estimated from the dimensional changes axially, tangentially, and radially. Confirmation was found by determining the density of dried specimens upon immersion in xylene. The amount of imbibed xylene provided an estimate of the free pore volume in the dried matrix. The volume fraction of the solid constituent, S, in the wet matrix was found to be 0.57, from which the density of S in various solutions was calculated. Density of wet matrix in 0.15 M saline: 1.180 g/cc; for dried matrix, 1.246 g/cc. Density of wet S in saline: 1.33 g/cc; for dried S, 1.42 g/cc, which matches published values for collagen molecules. Dimensional changes between wet and dried state of matrix match published values for artificially cross-linked rat tail tendon fibers. Axially: 1.04, by area: 2.27; by volume: 2.62. Estimate of intrafibrillar volume, assuming 80% of mineral is within fibrils: 0.73 cc/g dry collagen.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 33 (1981), S. 631-639 
    ISSN: 1432-0827
    Keywords: Bone ; Osteopenia ; Noninvasive monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Radiological techniques were utilized for monitoring progressive changes in compact bone in the tibia of monkeys during experimentally induced osteopenia. Bone mass loss in the tibia during restraint was evaluated from radiographs, from bone mineral analysis, and from images reconstructed from gamma ray computerized tomography. The losses during 6 months of restraint tended to occur predominantly in the proximal tibia and were characterized by subperiosteal bone loss, intracortical striations, and scalloped endosteal surfaces. Bone mineral content in the cross section of the tibia declined 17–21%. Tomography demonstrated endosteal widening and reduced mineral content per unit of thickness of cortical bone. In 6 months of recovery, the mineral content of the proximal tibia remained depressed. Effects of the dynamic environment on local-regional changes in various skeletal areas are discussed.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 33 (1981), S. 35-39 
    ISSN: 1432-0827
    Keywords: Copper ; Resorption ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary An investigation of the role of copper in bone metabolism was undertaken. Explanted calvaria from 6-day-old mice were grown for 48 h in medium with and without the addition of copper sulfate. Active resorption was found to be significantly inhibited in the presence of copper sulfate concentrations of 10−6M and above. Copper sulfate concentrations of 10−5M and above inhibited hydroxyproline, protein, and DNA synthesis. Lower concentrations were ineffective. The effect of 5 × 10−6M copper sulfate on resorption was reversible. Several other compounds were tested for similar effects and at 5 × 10−6M were found to inhibit bone resorption in the order: copper sulfate 〉 brown gold chloride 〉 sodium aurothiomalate 〉 zinc sulfate 〉 sodium sulfate. The copper sulfate effect was twice that of sodium aurothiomalate, and sodium sulfate was not significantly inhibitory. The results suggest that the high serum copper levels associated with rheumatoid arthritis may reflect the activity of a hypothetical control mechanism of bone resorption. In the diseased state this would act to restore the normal rate of bone resorption.
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  • 17
    ISSN: 1432-0827
    Keywords: Bone ; Mineral ; Amorphous calcium phosphate ; X-ray diffraction ; Radial distribution function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary X-ray diffraction radial distribution function analysis was used to determine if a significant amount of an amorphous solid phase of calcium phosphate exists in bone, and if so, whether the amount varies as a function of age and maturation. Unfractionated cortical bone from embryonic and posthatch chicks of various ages and a low-density fraction of embryonic bone were studied. No evidence was found for the presence of an amorphous solid phase of calcium phosphate in any of the samples studied, including the recently deposited bone mineral of the low density fraction of embryonic bone. As little as 12.5% of synthetic amorphous calcium phosphate (ACP) added to bone was readily detected by the radial distribution function technique used. The results clearly indicate that the concept that ACP is the initial solid mineral phase deposited in bone, and the major mineral constituent of young bone is no longer tenable. The concept does not provide an accurate description of the nature of the initial bone mineral deposited, or the changes that occur with maturation, nor can it acount for the compositional and X-ray diffraction changes that the mineral component undergoes during maturation and aging.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 36 (1984), S. S7 
    ISSN: 1432-0827
    Keywords: Bone ; Mechanical function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The variety of different mechanical functions required of whole bones is discussed. Often, the design optimizing the structure for one function is not optimal for another function.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 34 (1982), S. 337-342 
    ISSN: 1432-0827
    Keywords: Bone ; Histomorphology ; Immobilization ; Quadriplegia ; Multiple sclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The cortical bone histomorphometrics, total visible osteon density, and mean osteonal cross-sectional area were determined for the major long bones and sixth ribs of two individuals with neurological deficit. One was a multiple sclerosis patient who had been in a wheelchair for 15 years. The other was a quadriplegic as a result of poliomyelitis. Statistically significant differences in osteon densities occurred only in the case of the quadriplegic. Nevertheless, in that subject, the total visible osteon densities for bones of the right arm were not statistically different from those of their age-matched (control) radii. Medical history records revealed that there had been partial use of this limb. These results support the belief that mechanical stress is an important factor in the maintenance of normal cortical bone remodeling. In addition, since there were subnormal osteon densities and normal mean osteonal cross-sectional areas, immobilization appears to be characterized by reduced activation frequency with a normal amount of bone turnover per BMU.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 34 (1982), S. 376-381 
    ISSN: 1432-0827
    Keywords: Matrix vesicles ; Bone ; Actin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Preliminary indications of the occurrence of actin and myosin in crude matrix vesicle preparations have been reported previously. In the present study extracellular matrix vesicles from rat alveolar bone were isolated. They were further purified by a sucrose density gradient. SDS-polyacrylamide gel electrophoresis of the purified vesicles revealed the presence of a polypeptide with a molecular weight of 43 K daltons and with electrophoretic mobility identical to that of blood platelet actin. The limited proteolysis of both 43 K dalton vesicular polypeptide and actin byStaphylococcus aureus-V8-protease revealed three fragments with identical electrophoretic mobility. In addition, the vesicular preparations inhibited the activity of DNase I, a property typical of actin monomers. Filamentous material extracted from matrix vesicles showed ultrastructural features of F-actin. Reaction of this material with heavy meromyosin resulted in arrowhead formation, which is characteristic of acto-heavy meromyosin. The occurrence of actin in extracellular matrix vesicles may account for their budding from the osteoblastic plasma membrane, their possible motility in the matrix, and maintenance of the spherical shape.
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