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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 10 (1972), S. 67-81 
    ISSN: 1432-0827
    Keywords: Mineralization ; X-Ray absorption ; Microhardness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La méthode microradiographique-photométrique d'étude de l'absorption de rayons X, ainsi que la technique de microdureté, sont utilisées conjointement pour étudier la vitesse de minéralisation secondaire de l'os d'âge connu dans les ostéones de chiens jeunes et adultes. Les résultats des deux séries de mesures montrent une très bonne concordance. Ils montrent que la vitesse de la minéralisation secondaire a) décroit lentement et progressivement avec le temps dans chaque ostéone, b) subit peu de variations dans les divers ostéones de chaque sujet indépendemment de la vitesse de reconstruction, caractéristique de chaque région squelettique et c) décroit nettement avec l'âge de l'animal.
    Abstract: Zusammenfassung Die photometrische Methode zur Untersuchung der Mikroradiographien und die Mikrotechnik zur Beurteilung der Knochenhärte wurden beide zur Bestimmung der Geschwindigkeit der sekundären Mineralisation von Knochen bekannten Alters in den Osteonen von jungen und ausgewachsenen Hunden angewandt. Die Resultate beider Meß-Serien stimmten gut überein. Sie zeigten, daß die Geschwindigkeit der sekundären Knochenmineralisation a) mit der Zeit in jedem Osteon langsam und stetig abnimmt; b) kleinen Variationen in den verschiedenen Osteonen von jedem Tier unterliegt, unabhängig von der Neubildungsgeschwindigkeit, die für jede Skelettregion charakteristisch ist; c) mit dem Altern des Tieres beträchtlich abnimmt.
    Notes: Abstract The microradiographic-photometric method of studying the X-ray absorption, and the microhardness testing technique were concurrently applied to investigate the rate of secondary mineralization of bone of known age in the osteons of young immature and adult dogs. The results of the two series of measurement show a close agreement. They indicate that the rate of secondary mineralization, (a) slowly and progressively decreases with time in each osteon, (b) undergoes little variations in the various osteons of each subject independently of the reconstruction rate characteristic of each skeletal region, and (c) markedly decreases with the ageing of the animal.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 32 (1980), S. 221-228 
    ISSN: 1432-0827
    Keywords: Medullary bone ; Calcification ; Low-calcium diet ; Parathyroid hormone ; Estrogens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Medullary bone of birds maintained on a low-calcium diet represents a good model to study modifications of matrix composition in calcified tissue undergoing intense formation and resorption. The composition of the bone matrix during the low-calcium diet has been analyzed by both chemical and histological techniques. Sixty White Leghorn pullets 1 year old were used for the experiment. Fifteen birds served as controls and were killed on day zero; the remaining birds were placed on a calcium-deficient diet (0.13% calcium) and sacrificed after 4, 7, and 12 days of treatment in groups of 15. Serum levels of calcium, PTH, and estrogens were also measured. Chemical analysis of the samples were made for total nitrogen, hydroxyproline, hexosamine, hexoses, calcium, and phosphorus. Collagen and proteoglycans of the matrix of medullary bone of the egg-laying hens were found to be affected by the low-calcium diet. They either increased or decreased during the experiment but never in parallel. The increment of serum PTH is considered responsible for the variations in the amount of collagen. The effects of this hormone are magnified by the fall of serum estrogens as shown also by variations in the amounts of noncollagenous protein. In the late phase of the diet the matrix is represented by poorly calcified osteoid tissue rich in noncollagenous protein, i.e., proteoglycans and glycoproteins.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 235 (1984), S. 561-564 
    ISSN: 1432-0878
    Keywords: Osteoclasts ; Bone cell cultures ; Bone resorption ; Osteoblasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The maintainance of resorptive capability towards vital or devitalized bone in osteoclasts isolated from the medullary bone of laying hens and cultured for five days in vitro has been investigated morphologically with the aid of light and transmission electron microscopy. Devitalized bone particles ranging in size from 50 to 100 μm, added to cultures of osteoclasts, were rapidly surrounded by the osteoclasts which, in transmission electron microscopy, showed ruffled borders and clear zones at the surfaces of contact with bone — features typical of resorptive activity. Alternatively osteoclasts were added onto the endosteal surfaces of vital or devitalized diaphyses of quail femurs after removal of the endosteal and periosteal cell layers. The results indicated that, when the vital or devitalized bone surfaces were devoid of cells, the osteoclasts adhered and resorbed bone (as confirmed by transmission electron microscopy). When vital bone of quail was cultured for 24 h before the addition of osteoclasts a new cell layer was formed; it enveloped all bone surfaces and precluded the access of osteoclasts to bone. The role of these lining cells, ultrastructurally indistinguishable from resting osteoblasts, is discussed.
    Type of Medium: Electronic Resource
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