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  • Bone  (2)
  • Springer  (2)
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  • Springer  (2)
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  • 1
    ISSN: 1432-0827
    Keywords: Electron spin resonance ; Crystallinity ; Bone ; Osteons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Several groups containing 10–15 isolated osteons differing in their degree of maturity were analysed. Samples were isolated from undecalcified human and bovine bone sections. The crystallinity coefficient, defined as the ratio of the number of radiation-induced paramagnetic defects in the crystalline lattice of hydroxyapatite to the total ash content, was calculated. The results were compared with measurements performed on fragments of total cortical bone, primary periosteal bone, and inner circumferential lamellar bone. The results show a higher crystallinity of fully calcified osteons as compared with that found at the initial stage of calcification. No differences in the ash content were observed between human osteons, from different stages of calcification evaluated morphologically and by X-ray absorption. These differences were evident when bovine osteons differing in their stage of calcification were compared. Human fully calcified osteons contain 60% ash and their crystallinity coefficient is 52.1. Human osteons at the initial stage of calcification contain 57% ash and their crystallinity coefficient is 40.6. The same parameters for fully calcified bovine osteons and for bovine osteons at the initial stage of calcification are 59% ash, 62.6 crystallinity coefficient and 46% ash, 43.0 crystallinity coefficient, respectively.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0827
    Keywords: Electron spin resonance ; Resorption ; Irradiation ; Bone ; Graft
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La technique de la résonance aux électrons (ESR) a été utilisée pour étudier la résorption et la substitution progressive de greffons osseux stérilisés par irradiation (à une dose de 3.3 Mrads) chez le lapin et le chien. Le signal stable d'ESR, émis par la perte de substance structurale induite par le rayonnement au niveau du minéral osseux, est utilisé comme marqueur biologique. La concentration de résonance et le nombre total des centres paramagnétiques sont mesurés avant et après greffe. Ue décroissance progressive de la concentration de résonance et du nombre total des centres paramagnétiques est observée après des intervalles de temps variables, faisant suite à l'implantation. En considérant la stabilité inhabituelle et le manque de réactivité chimique des centres paramagnétiques intéressés, il apparait que la décroissance des intensités du signal ESR observé indique une résorption et une substitution progressive. Cette méthode parait intéressante pour des recherches sur les tissues calcifiés.
    Abstract: Zusammenfassung Zur Erforschung der Resorption und der schleichenden Substitution von radiosterilisierten (Dosis: 3,3 Mrad) Knochentransplantaten bei Kaninchen und Hunden wurde die Technik der elektronischen Drehresonanz (ESR) angewendet. Als biologische Markierung diente das stabile ESR-Signal, welches aufgrund des bestrahlungsbedingten Strukturdefektes im Knochenmineral entsteht. Die Drehkonzentration und die Gesamtzahl der paramagnetischen Zentren wurden vor und nach dem Transplantieren gemessen. In verschiedenen Zeitintervallen konnte nach der Implantierung eine allmähliche Abnahme der Drehkonzentration sowie der Gesamtzahl der paramagnetischen Zentren beobachtet werden. Aus der ungewöhnlichen Stabilität und der fehlenden chemischen Reaktionsfähigkeit der beteiligten paramagnetischen Zentren wird geschlossen, daß die beobachtete abnehmende ESR-Signalintensität ei Zeichen für die zunehmende Resorption und Substitution ist. Es scheint, daß mit der besprochenen Technik eine brauchbare Methode zur Erforschung von mineralisiertem Gewebe zur Verfügung steht.
    Notes: Abstract The electron spin resonance (ESR) technique has been applied to the investigation of the resorption and creeping substitution of radiosterilized (3.3 Mrads dose) bone grafts in rabbits and dogs. The stable ESR signal arising from the radiation-induced structural defect in bone mineral was used as a biological label. the spin concentration and the total number of paramagnetic centres were measured before and after grafting. The gradual decrement of spin concentration as well as that of total number of paramagnetic centres were observed at varioust ime intervals after implantation. On the basis of the unusual stability and lack of chemical reaction of the paramagnetic centres involved, it is concluded that the decrease of the observed ESR signal intensities indicates progressive resorption and substitution. it seems that the proposed method can be useful for research o mineralized tissues.
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