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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 8 (1971), S. 228-236 
    ISSN: 1432-0827
    Keywords: Skin ; Calcinosis ; Keratin ; Chemistry ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des études histologiques antérieures ont montré que le follicle pileux est particulièrement susceptible de se calcifier, lorsque la peau de rats hypercalcémiques est lésée. Des analyses chimiques et par diffraction aux rayons X du follicule ont confirmé ce résultat. — En se basant sur l'augmentation du calcium et du phosphore, les calcifications débutent dans le tissue folliculaire 6–12 h après une blessure d'intensité moyenne de la peau de rats, ayant reçu du dihydrotachysterol (DHT), et 24–48 h après une blessure similaire chez des rats non injectés. Les diagrammes de diffraction aux rayons X sont diffus. Trois heures après la blessure, on note une augmentation du calcium du tissu folliculaire qui ne semble pas en rapport avec le DHT qui traduit probablement une liaison de calcium plutôt qu'un dépot minéral.
    Abstract: Zusammenfassung Frühere histologische Untersuchungen haben gezeigt, daß der Haarfollikel besonders anfällig für Verkalkungen ist, wenn die Haut von hypercalcämischen Ratten verletzt wird. Dieses Resultat wurde nun durch direkte chemische Bestimmungen und Röntgendiffraktions-analysen von Follikelgewebe bestätigt. Aufgrund der erhöhten Calcium- und Phosphatwerte kann gesagt werden, daß nach einer leichten Quetschung der Haut von Ratten, die mit Dihydrotachysterol (DHT) behandelt wurden, im Haarfollikelgewebe nach 6–12 Std Mineral-ablagerungen stattfanden, wogegen Kontrollratten mit der gleichen leichten Hautverletzung diese Ablagerungen erst nach 24–48 Std zeigten. Röntgendiffraktionsanalysen ergaben ein diffuses Apatit-Muster. Innerhalb 3 Std nach der Verletzung wurde ein Anstieg des Calcium-gehaltes im Follikelgewebe beobachtet, der nicht im Zusammenhang mit der DHT-Behandlung stand, also nicht eine Mineralablagerung, sondern eher eine Bindung von Calcium widerspiegelte.
    Notes: Abstract Previous histological investigations have shown that the hair follicle is particularly susceptible to mineralization when the skin of hypercalcaemic rats is injured. Direct chemical and X-ray diffraction analyses of follicle tissue have now confirmed this finding. As judged by increases in both calcium and phosphorus, mineral deposits began to form in hair follicle tissue 6–12 h after a mild crush injury to the skin of rats dosed with dihydrotachysterol (DHT), and 24–48 h after a similar injury to the skin of non-dosed rats. X-ray diffraction gave a diffuse apatite pattern. Within 3 h of injury there was a rise in the calcium content of follicle tissue which was not related to DHT-dosing and which was probably a reflection of calcium binding rather than mineral deposition.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 33 (1981), S. 395-402 
    ISSN: 1432-0827
    Keywords: Macromolecule adsorption ; Hydroxyapatite ; Ion movements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Certain small anionic molecules displace phosphate ions from the hydroxyapatite crystal hydration layer on adsorption. This follows the interaction of negatively charged groups with calcium ions in the crystal surface. The present study examines ion-exchange processes occurring during the adsorption of anionic macromolecules and attempts to determine the role of coulombic forces in the process. Various natural and synthetic polyanionic substances were added to a buffered hydroxyapatite slurry and adsorption measured by solution depletion. Calcium and phosphate ion displacement or uptake by apatite was determined after accounting for polymer-bound ions. Carboxymethylcellulose and a polyacrylamide sample in which 54% of amide groups had been hydrolyzed to carboxyl were adsorbed in the lowest amounts, but both caused consistent rises in the bulk solution phosphate level. Crude bovine submaxillary mucin and a polyacrylamide sample in which 28% of amide groups had been hydrolyzed were adsorbed in greater amounts but caused little or no phosphate displacement. In no case was there a stoichiometric relation between carboxyl adsorbed and phosphate displaced. The polyacrylamide samples also displaced Ca ions into the bulk solution, whereas the other macromolecules caused a decrease in solution Ca concentration. These results provide some evidence for the operation of an ion-exchange mechanism in the adsorption of polyanions on hydroxyapatite but do not exclude the involvement of other mechanisms, especially in the case of salivary mucin.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 15 (1974), S. 133-141 
    ISSN: 1432-0827
    Keywords: Injury ; Keratin ; Hair follicle ; Nucleation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract When the skin of rats is middly injured, mineral deposits form in some hair follicles in the injured area (Cousins and Smillie 1965). It was suggested that this could have resulted from the injury-induced modification of hair follicle proteins to form an efficient nucleator from a normally inactive precursor. S-carboxymethyl kerateine derivatives of follicle proteins were subjected to chromatography on diethylaminoethyl cellulose and to starch gel electrophoresis. No differences could be detected by these techniques between follicle keratins from injured skin and those from uninjured skin. This indicated that efficient nucleating material is normally present in hair follicles and is not formed following injury. This is discussed in relation to previous work on follicular mineralization.
    Type of Medium: Electronic Resource
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