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  • Collagen
  • Hydroxyapatite
  • Metabolism
  • Springer  (76)
  • American Geophysical Union
  • American Physical Society
  • 1980-1984  (59)
  • 1965-1969  (17)
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Keywords
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  • 1
    Electronic Resource
    Electronic Resource
    The effect of some inhibitors on the nucleation and crystal growth of apatite (1969)
    Springer
    Calcified tissue international 3 (1969), S. 348-357 
    Details
    ISSN: 1432-0827
    Keywords: Inhibitors ; Nucleation ; Apatite ; Collagen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des ions de Mg, Sr et F sont inhibitoires pour la formation de l'apatite quand on les ajoute à un tampon de calcification, séparément ou en combinaisons. La précipitation de l'apatite causée par des cristaux d'apatite est moins sensible à l'action inhibitrice que la nucléation spontanée et que la précipitation catalysée par la collagène d'os de mouton. La précipitation spontanée ou catalysée sont approximativement aussi sensibles. L'inhibition par des combinaisons de Mg avec des ions de Sr ou de F est additive. Ces résultats montrent que ces inhibiteurs ont acucune action spécifique sur la catalysation par la collagène de l'os de mouton qui soit différente de celle sur la nucléation de l'apatite en soi.
    Abstract: Zusammenfassung Mg, Sr und F Ionen hemmten die Fällung von Apatit wenn sie zu einem Calciumphosphatpuffer einzeln oder zusammen hinzugefügt wurden. Die Fällung von Apatit durch Apatitkeime war weniger empfindlich hinsichtlich der Hemmung als die spontane Nucleation und als die Fällung von Apatit, welche von Schafsknochenkollagen katalysiert werden kann. Die spontane und katalysierte Fällung sind ungefähr gleich empfindlich. Die Hemmung von Mg in Kombination mit Sr oder F Ionen war additiv. Diese Resultate weisen darauf hin, daß keine spezifischen Effekte bei der Katalyse von Knochenkollagen vorliegen, welche von den Effekten bei der Nucleation von Apatit an sich verschieden sind.
    Notes: Abstract Mg, Sr and F ions acted as inhibitors of apatite formation when added to a calcification buffer separately or in combinations. The precipitation of apatite under the influence of apatite seeds was less susceptible to inhibition than were spontaneous nucleation and apatite formation catalyzed by sheep bone collagen, while the latter two were about equally susceptible. Combinations of Mg with Sr or F ions showed additive effects. These results suggest that no specific effects of these inhibitors occurred on the catalytic action of the bone collagen different from their effects on the nucleation of apatite as such.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02058677
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  • 2
    Electronic Resource
    Electronic Resource
    Collagen crosslinks in human dentin: Increasing content of hydroxypyridinium residues with age (1983)
    Springer
    Calcified tissue international 35 (1983), S. 401-405 
    Details
    ISSN: 1432-0827
    Keywords: Collagen ; Crosslinks ; Dentin ; Human ; Bovine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The hydroxypyridinium crosslinks of collagen are believed to derive from reducible, divalent crosslinks. To study this concept further, both types of crosslink were quantified as a function of age in dentin, a tissue thought to have minimal collagen turnover. Human (5, 15, 28 and 56 years) and bovine (fetal and adult) root dentin was analyzed by a procedure that measures both hydroxypyridinium and reducible crosslinks on the amino acid analyzer. In human dentin, hydroxypyridinium crosslinks increased with age and became the predominant crosslinks as the two reducible residues, dehydrodihydroxylysinonorleucine and dehydrohydroxylsinonorleucine, diminished. Similarly in adult bovine dentin, hydroxypyridinium residues were sixfold more concentrated than in fetal bovine dentin. Borohydride treatment of tissue did not influence the measured content of hydroxypyridinium residues. The analyses also ruled out natural reduction as a stabilizing reaction for the divalent, reducible crosslinks. Though hydroxypyridinium residues became the major aldehyde-mediated crosslinks of adult dentin collagen, significant levels of reducible crosslinks remain throughout the tooth's adult life.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405067
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of epidermal growth factor on osteoblastic cellsin vitro (1983)
    Springer
    Calcified tissue international 35 (1983), S. 542-548 
    Details
    ISSN: 1432-0827
    Keywords: Osteoblasts ; Epidermal growth factor ; Alkaline phosphatase ; Collagen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effect of epidermal growth factor (EGF) on clone MC3T3-El cells that have osteoblastic activity was examined by phase-contrast microscopy and electron microscopy; hydroxyproline content, collagen synthesis, collagen pattern, and alkaline phosphatase (ALP) activity were also determined. We found that EGF (0.4 ng/ml) transformed the cells from their normal polygonal shape to a spindle-like morphology by 8 h. This hormone also caused dose-related suppression of hydroxyproline content and ALP activity which was detectable 2 days and 1 day, respectively, after EGF addition. Indomethacin did not affect hydroxyproline content and ALP activity, suggesting that the effect of EGF on the cells may not be mediated by prostaglandins. Epidermal growth factor at concentrations of 2 to 50 ng/ml significantly decreased collagen synthesis in the cells, whereas protein synthesis was stimulated. Electron microscopy demonstrated that collagen fiber formation was also reduced by EGF; an immature type of fibril was observed compared with the typical cross-striated one in the controls. Moreover, the hormone treatment also resulted in the appearance of type III collagen in addition to the type I already present in the cells. These suppressive effects of EGF on MC3T3-El cellsin vitro suggest that this hormone may be involved in bone remodellingin vivo as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405091
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  • 4
    Electronic Resource
    Electronic Resource
    Structural factors influencing the ability of compounds to inhibit hydroxyapatite formation (1982)
    Springer
    Calcified tissue international 34 (1982), S. 169-177 
    Details
    ISSN: 1432-0827
    Keywords: Amorphous calcium phosphate transformation ; Hydroxyapatite ; Turbidimetry ; Inhibitor types ; Structure-activity relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary For a compound to inhibit potently the transformation of amorphous calcium phosphate into hydroxyapatite, it is suggested that the minimum structural requirement is a phosphate group and, at some other position, either another phosphate group preferably or a carboxylic moiety. Primary amino groups abolish inhibitor potential. Inhibitor potency is modified by various secondary factors, including the number and proximity of active groups, their stereochemistry, steric factors, the lability of the molecule, and in special instances its lipophilicity. Parameters used to monitor the transformation indicate that inhibitors can be grouped into two classes, and it is suggested that this is because one class acts as a hydroxyapatite crystal growth inhibitor. The close proximity of two phosphate groups or of a phosphate and multiple carboxylic groups is proposed to determine in part whether or not a compound acts as a crystal growth inhibitor. Further, bulky side groups render a molecule inactive as a crystal growth poison, although it will still inhibit by other mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02411229
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  • 5
    Electronic Resource
    Electronic Resource
    High-resolution electron microscopy of octacalcium phosphate and its hydrolysis products (1984)
    Springer
    Calcified tissue international 36 (1984), S. 219-232 
    Details
    ISSN: 1432-0827
    Keywords: Octacalcium phosphate ; Hydroxyapatite ; Hydrolysis ; Lattice imaging ; Crystallographic disorder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The hydrolysis and dehydration products of synthetic octacalcium phosphate (OCP) were studied using X-ray diffraction, infrared spectroscopy, chemical analysis, and high-resolution electron microscopy (HREM). A “collapsed OCP” phase, identified by a characteristic 16.5 Å reflection in its X-ray diffraction pattern, was observed when OCP was dehydrated. High resolution electron microscopy of the hydrolyzed and partially hydrolyzed reaction products also revealed local contrast features with an approximate 16.5 Å periodicity. These features were consistent with a collapse of the OCP crystal structure and subsequent formation of epitaxial intergrowths of OCP and hydroxyapatite. Chemical analysis and X-ray diffraction of these samples were similar to previously reported calcium-deficient apatites. The hydrolysis of OCP to form calcium-deficient apatities is a reaction pathway which may be of importance in understanding the crystallographic changes occurring during the early stages of bone, calculus, and dental enamel formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405321
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  • 6
    Electronic Resource
    Electronic Resource
    The effect of excessive acid feeding on bone (1969)
    Springer
    Calcified tissue international 4 (1969), S. 94-100 
    Details
    ISSN: 1432-0827
    Keywords: Acid ; Base equilibrium ; Acidosis ; Bone ; Resorption ; Metabolism ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'administration chronique de chlorure d ammonium à des rats adultes normaux, soumis à un régime contenant un taux approprié de vitamine D, provoque une ostéoporose. Celle-ci est provoquée par une perte de substance d'os et de minéral osseux, associée à l'augmentation de la résorption osseuse.
    Abstract: Zusammenfassung Chronische Verabreichung von Ammoniumchlorid an normale ausgewachsene männliche Ratten, die eine entsprechende Vitamin-D-haltige Diät erhalten, verursacht die Entwicklung einer Osteoporose. Die Osteoporose entsteht auf Grund eines Verlustes von Knochensubstanz und Knochenmineral, in Begleitung einer erhöhten Knochenresorption.
    Notes: Abstract Excessive administration of ammonium chloride to normal adult male rats receiving a diet adequate in vitamin D caused the development of osteoporosis. The osteoporosis was due to loss of bone substance and bone mineral associated with increased bone resorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02279111
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  • 7
    Electronic Resource
    Electronic Resource
    Relationship between iron, calcium and phosphate during experimental cutaneous calcinosis (1969)
    Springer
    Calcified tissue international 4 (1969), S. 224-230 
    Details
    ISSN: 1432-0827
    Keywords: Calcinosis ; Calcium ; Iron ; Phosphate ; Collagen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La calcification de la peau (calciphylaxie) provoquée par l'administration sous-cutanée de chlorure de fer chez des rats sensibilisés par le dihydrotachystérol (DHT) est précédée par une déposition sélective de fer (décelable à la microscopie électronique) à la surface des fibres collagènes. Les analyses à la microsonde prouvent que les taux de calcium et de phosphore sont augmentés à l'endroit de l'injection du chlorure de fer même sans l'administration préalable de DHT; cependant, l'apatite ne se forme que chez les animaux prétraités par le DHT. La quantité et le degré de cristallinité de la matière inorganique sont presque identiques au sixième et au trentième jour de l'expérience.
    Abstract: Zusammenfassung Durch elektronenmikroskopische Untersuchungen wurde festgestellt, daß die durch subcutane Verabreichung von Eisenchlorid bei Dihydrotachysterin-sensibilisierten Ratten herbeigeführte Hautverkalkung durch eine selektive Eisenablagerung auf der Oberfläche der Kollagenfibrillen eingeleitet wird. Die Röntgenmikroanalyse zeigt an, daß die lokale Calciumund Phosphorkonzentration bereits nach Eiseninjektion allein ansteigt, während Apatitbildung nur in den mit DHT vorbehandelten Tieren erfolgt. Ausmaß und Menge der Kristallisation sind am 6. und 30. Tage nach Versuchsbeginn fast gleich.
    Notes: Abstract Calcification of the skin (calciphylaxis) induced by the subcutaneous administration of iron chloride to dihydrotachysterol (DHT)-sensitized rats is preceded by the selective deposition of iron (visible with electron microscopic techniques) on the surface of collagen fibrils. Electron probe X-ray microanalysis indicates that the injectionof iron alone suffices to increase local concentrations of calcium and phosphorus; however, apatite formation occurs only in animals pretreated with DHT. The amount and degree of crystallinity of the inorganic material is very similar on the sixth and thirtieth day after the beginning of the experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02279125
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  • 8
    Electronic Resource
    Electronic Resource
    The effect of electric current on rat tail tendon collagen in solution (1969)
    Springer
    Calcified tissue international 4 (1969), S. 330-338 
    Details
    ISSN: 1432-0827
    Keywords: Collagen ; Electric current ; Electrolysis ; Precipitation ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'effet du courant électrique sur la collagène soluble, en solution dans l'acide acétique dilué, a été étudié pour des voltages, variant de O à 25 volts. Au-dessus de 2,6 volts, la vormation des bandes collagéniques (définies dans ce travail) parait inversement proportionelle, dans le temps, au voltage appliqué. La formation des bandes parait liée au processus d'électrolyse. Les auteurs démontrent que les pH élevés se situent au niveau de la cathode et qu'ils sont suffisants pour induire une précipitation du collagène. Les résultats antérieurs, publiés dans la littérature, décrivant l'action de courant électrique implanté, sont interpretés en fonction du mécanisme étudié au cours de ce travail.
    Abstract: Zusammenfassung Die Wirkung eines elektrischen Stromes auf verdünnte essigsaure Lösungen von löslichem Kollagen wurde bei Spannungen zwischen O und 25 Volt untersucht. Über 2,6 Volt wurde die Bildung von Kollagenbanden (in der Arbeit näher beschrieben) beobachtet, und zwar nach Zeiten, die der angewandten Spannung entgegengesetzt proportional verliefen. Die Bandenbildung wird dem Elektrolyseprozeß zugeschrieben. Wir konnten zeigen, daß sich die hohen pH-Werte rund um die Kathode entwickelten und daß diese genügen, um die Kollagenfällung zu veranlassen. Die Natur dieses Vorganges ist solcher Art, daß erin vivo als Antwort auf durch Stress verursachte Biopotentiale nicht vorkommen kann. Der hier beschriebene Mechanismus erlaubt es, Literaturangaben über den Effekt von implantierten Spannungsquellen zu interpretieren.
    Notes: Abstract The effect of electric current on dilute acetic acid solutions of soluble collagen has been studied for impressed voltages of from 0 to 25 volts. Above 2.6 volts the formation of collagen bands (herein defined) were observed at times inversely proportional to the applied voltage. Band formation is attributed to the process of electrolysis. It has been shown that the high pH values are generated in the area of the cathode, and that they are sufficient to induce collagen to precipitate. The nature of the process is such that it cannot occurin vivo as a response to stress induced biopotentials. Reports in the literature describing the effect of implanted voltage sources are interpreted in terms of the mechanism described here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02279135
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  • 9
    Electronic Resource
    Electronic Resource
    Stereochemically altered noncollagenous protein from human dentin (1983)
    Springer
    Calcified tissue international 35 (1983), S. 43-47 
    Details
    ISSN: 1432-0827
    Keywords: Noncollagenous protein ; Dentin ; Aging ; Racemization ; Collagen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Highly phosphorylated noncollagenous proteins (NCP) with molecular weights of ∼70–100,000 daltons have been purified from rat and bovine dentin. Efforts to isolate phosphoprotein from human teeth have not yielded consistent results, and failures have been attributed to proteolysis due to preparative techniques. Diagenetic reactions affecting metabolically stable proteinsin vivo also can interfere in protein purification. Racemization is one of the reactions known to take place in human dentin. EDTA extraction of dentin from an age-graded series of human teeth has yielded an EDTA-soluble NCP fraction having an aspartic acid racemization rate 3 X that in unfractionated dentin and 8 X the rate in EDTA-insoluble protein. D-Aspartic acid is accumulating in EDTA-S protein at a rate of 0.22% yr−1. For humans, more than 13% of the aspartyl residues in NCP will be the D-enantiomer by 60 years of age. While racemization presents no problem for shorter lived mammals, such as rats, it could be partly responsible for purification difficulties with human dentin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405005
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  • 10
    Electronic Resource
    Electronic Resource
    Correlated physicochemical and age changes in embryonic bovine enamel (1983)
    Springer
    Calcified tissue international 35 (1983), S. 48-55 
    Details
    ISSN: 1432-0827
    Keywords: Enamel ; Density centrifugation ; Hydroxyapatite ; Carbonate ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Whole enamel scrapings from unerupted teeth of embryonic calves have been separated into fractions of varying density by stepwise centrifugation in bromoform-toluene mixtures of increasing specific gravity. Partition of enamel in this manner yields individual fractions of increasing mineral phase age and maturation. Whole scrapings and isolated fractions of the fetal bovine enamel were examined by X-ray powder diffraction, scanning electron microscopy, and atomic absorption and infrared spectroscopy to determine time-related changes in the physicochemical nature of the constituent mineral phase particles. These analyses showed poorly crystalline hydroxyapatite (HA) as the only detectable solid phase of calcium phosphate present in all fractions, its degree of crystallinity increasing with increasing density. Molar Ca/P ratios and magnesium content were highest in lowest density fractions. Carbonate vibration bands at 875 and 1420–1450 cm−1, common to mineralized tissue, were observed in intermediate and higher density fractions and in whole unfractionated enamel. Another carbonate band at ∼705 cm−1, unusual to vertebrate calcified tissue, was detected in low density fractions and disappeared rapidly with increasing enamel maturation. Its precise relation with the enamel mineral phase has not been determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405006
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  • 11
    Electronic Resource
    Electronic Resource
    Template-directed synthesis and selective adsorption of oligoadenylates on hydroxyapatite (1980)
    Springer
    Journal of molecular evolution 15 (1980), S. 347-354 
    Details
    ISSN: 1432-1432
    Keywords: Adenosine 5′-phosphorimidazolide ; Template-directed condensation ; Oligoadenylates ; Adsorption ; Hydroxyapatite ; Prebiotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Polyuridylic acid is adsorbed completely from aqueous solution by hydroxyapatite under conditions that permit template-directed synthesis of oligoadenylates in free solution. The yield of oligoadenylates is enhanced to almost the same extent by poly(U) in the presence or the absence of hydroxyapatite. Under very similar conditions small quantities of hydroxyapatite adsorb higher molecular-weight oligoadenylates selectively from a mixture of oligomers. On the basis of these results we propose a mechanism for prebiotic oligonucleotide formation in which selective adsorption on hydroxyapatite or some other immobilized anion-exchanging material plays a major role. Monomers are released from the surface for reactivation, while oligomers are retained in a protected environment by adsorption to the apatite surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01733141
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  • 12
    Electronic Resource
    Electronic Resource
    Evolution of sea urchin non-repetitive DNA (1980)
    Springer
    Journal of molecular evolution 16 (1980), S. 95-110 
    Details
    ISSN: 1432-1432
    Keywords: Evolutionary Divergence ; DNA ; Single copy ; Thermal Stability ; S1 Nuclease ; Hydroxyapatite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary New methods have been applied to the determination of single copy DNA sequence differences between the sea urchin speciesStrongylocentrotus purpuratus, S. franciscanus, S. drobachiensis, andLytechinus pictus. The thermal stability of interspecies DNA duplexes was measured in a solvent (2.4 M tetraethylammonium chloride) that suppresses the effect of base composition on melting temperature. The lengths of duplexes were measured after digestion with S1 nuclease and correction made for the effect of length on thermal stability. The degree of base substitution that has occurred in the single copy DNA during sea urchin evolution is significantly larger than indicated by earlier measurements. We estimate that 19% of the nucleotides of the single copy DNA are different in the genomes of the two sea urchin congeners,S. purpuratus, andS. franciscanus, which apparently diverged only 15 to 20 million years ago.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01731580
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  • 13
    Electronic Resource
    Electronic Resource
    Fibronectin from the ovary of the sea urchin,Pseudocentrotus depressus (1981)
    Springer
    Development genes and evolution 190 (1981), S. 83-86 
    Details
    ISSN: 1432-041X
    Keywords: Sea urchin ; Fibronectin ; Collagen ; Basement membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Fibronectin, with a subunit molecular weight of 220,000 daltons, was isolated from the ovary of the sea urchin,Pseudocentrotus depressus, using affinity chromatography on heat-denatured mammalian collagen coupled to Sepharose 4B. The distribution of fibronectin in the sea urchin ovary was examined by indirect immunofluorescence using antifibronectin serum. The basement membrane and the connective tissues exhibited strong fluorescence. The fibronectin was localized closely together with collagen bundles in the sea urchin ovary. Biochemical and immunological examinations indicate that sea urchin fibronectin has similar properties as those of mammalian fibronectin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848399
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  • 14
    Electronic Resource
    Electronic Resource
    Immunofluorescent localization of collagen types I, III, IV, fibronectin and laminin during morphogenesis of scales and scaleless skin in the chick embryo (1983)
    Springer
    Development genes and evolution 192 (1983), S. 205-215 
    Details
    ISSN: 1432-041X
    Keywords: Collagen ; Fibronectin ; Laminin ; Skin ; Scale morphogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Collagen types I and III were purified from the skin of 3-or 7-week-old chickens, collagen type IV from bovine skin or EHS mouse tumour, fibronectin from human serum, and laminin from EHS mouse tumour. Antibodies were produced in rabbits or sheep, and used in indirect immunofluorescence on frozen sections of 9-to 16-day-old normal or mutant (scaleless) chick-embryo foot skin. In normal scale-forming skin and inscaleless skin, the distribution of anti-laminin and anti-type IV collagen label was uniform along the dermal-epidermal junction and showed no stage-related variations, except for fluorescent granules located in the dermis of early scale rudiments. By contrast, in normal scale-forming skin, the density of anti-types I and III label decreased in the dermis within scale rudiments, whereas it gradually increased in interscale skin. Conversely, anti-fibronectin label accumulated at a higher density within scale rudiments than in interscale skin. In the dermis of thescaleless mutant, anti-types I and III label and antifibronectin label were distributed evenly: the density of anti-collagen label increased with age, while that of antifibronectin decreased and almost completely vanished in 16-day-old skin, except around blood vessels. The microheterogeneous distribution of some extracellular matrix components, namely interstitial collagen types I and III and fibronectin, is interpreted as part of the morphogenetic message that the dermis is known to transmit to the epidermis during the formation of scales. The even distribution of these components in mutantscaleless skin is in agreement with this view. Basement membrane constituents laminin and type-IV collagen do not appear to be part of the dermal morphogenetic message.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848651
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  • 15
    Electronic Resource
    Electronic Resource
    Ion displacement following the adsorption of anionic macromolecules on hydroxyapatite (1981)
    Springer
    Calcified tissue international 33 (1981), S. 395-402 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02409462
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  • 16
    Electronic Resource
    Electronic Resource
    Tissue deposition and metabolism of125I-labeled synthetic amino-terminal parathyroid hormone bPTH(1–34) (1980)
    Springer
    Calcified tissue international 30 (1980), S. 147-150 
    Details
    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Distribution ; Metabolism ; Heterogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The tissue deposition and metabolism of125I-labeled synthetic amino-terminal parathyroid hormone, bPTH(1–34), were studied in rats. In comparison with the intact hormone molecule bPTH(1–84), the synthetic fragment was (a) cleared more rapidly from serum; (b) degraded more rapidly in peripheral tissues; (c) deposited to a greater extent in kidney; (d) deposited to a much smaller extent in liver. In bone, the accumulation of total radioactivity was approximately the same with both labeled hormones. The possible physiological significance of these patterns of distribution and metabolism is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408619
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  • 17
    Electronic Resource
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    Relationship between proteolipids and calcium-phospholipid-phosphate complexes inBacterionema matruchotii calcification (1980)
    Springer
    Calcified tissue international 30 (1980), S. 167-174 
    Details
    ISSN: 1432-0827
    Keywords: Proteolipid ; Calcium-phospholipid-phosphate complexes ; Calcification ; Hydroxyapatite ; Membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Calcium-phospholipid-phosphate complexes (Ca-PL-P) were isolated from calcified and uncalcifiedBacterionema matruchotii and its calcified lipid extracts. Similar complexes were absent from the noncalcifying bacteriumActinomyces naeslundii. The majority of the Ca-PL-P complexes were associated with the proteolipid acidic phospholipid component. Ca-PL-P complexes isolated fromB. matruchotii and from calcified proteolipid contained phosphatidylinositol, phosphatidylinositol-4-phosphate, phosphatidylinositol-4,5-diphosphate, and phosphatidylserine. They consisted of approximately 52 mole % Ca, 32 mole % organic P, and 15 mole % Pi. During Ca-PL-P extraction fromB. matruchotii or its proteolipid-containing calcified lipid extracts, the proteolipid was dissociated and the apoprotein precipitated as fluff at the aqueous-organic solvent interface, thus explaining the failure to detect protein in Ca-PL-P preparations. When the ability of Ca-PL-P complexes and lipid fractions ofB. matruchotii to initiate apatite formation from metastable calcium phosphate solution was compared, the yield of hydroxyapatite decreased as follows: Ca-PL-P 〉 proteolipid acidic phospholipids 〉 proteolipid 〉 crude phospholipid 〉 total lipids 〉 whole cells.
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    Co-isolation of proteolipids and calcium-phospholipid-phosphate complexes (1984)
    Springer
    Calcified tissue international 36 (1984), S. 214-218 
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    ISSN: 1432-0827
    Keywords: Proteolipid ; Calcium-phospholipid-phosphate complexes ; Calcification ; Hydroxyapatite ; Membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary This study demonstrates that calciumphospholipid-phosphate complexes (CPLX) and calcifiable proteolipid are associatedin vivo by establishing that they can be co-isolated from calcified bacteria. Both of these membrane constituents, which support apatite formationin vitro, have been isolated independently fromBacterionema matruchotii. However, isolation of proteolipid was preceded by demineralization in 2N formic acid, thereby dissociating bound Ca, whereas isolation of CPLX included sonication of calcified bacteria in 2:1:1.5 chloroform:methanol:Tris buffer, thereby dissociating any protein. Co-isolation is possible by demineralizing the calcified bacteria with 50 mM phthalic acid, pH 5.5, followed by extraction with 2:1 chloroform:methanol, and precipitation of crude phospholipid with acetone. CPLX and proteolipid are present in all Sephadex LH-20 chromatographic fractions of the crude phospholipid and of diethyl ether precipitates of the crude phospholipid. CPLXs contain protein:phospholipid:Ca:Pi but differ in relative composition from each other and from independently isolated CPLX. The Ca:phospholipid:Pi molar ratio of diethyl ether precipitable proteolipid-CPLX is most similar to previously published values for CPLX. The protein content of CPLX accounts for all of the proteolipid apoprotein in each Sephadex LH-20 fraction.
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    Fluoride absorption: The influence of gastric acidity (1984)
    Springer
    Calcified tissue international 36 (1984), S. 302-307 
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    ISSN: 1432-0827
    Keywords: Metabolism ; pH ; Fluorosis ; Osteoporosis ; Toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The influence of gastric acidity on the absorption of intragastrically administered fluoride was investigated in rats. Intact animals were pretreated with atropine or cimetidine to reduce gastric acid secretion or were given fluoride in NaHCO3 to reduce the acidity of the gastric contents. Compared with pentagastrin-treated animals or animals that received fluoride in 0.1 N HCl, their rate of fluoride absorption was markedly reduced as judged by lower plasma fluoride concentrations and areas under the time-plasma concentration curves, especially during the first hour after dosing. In crossover studies with the stomachs isolatedin situ, fluoride absorption was at least 50% faster from a pH 2.1 buffer compared with its absorption from a pH 7.1 buffer. The findings are consistent with the hypothesis that fluoride is absorbed from the gastric lumen principally as the undissociated molecule, HF. The results may contribute to a more complete understanding of acute fluoride toxicity, the development of dental fluorosis and, perhaps, the use of fluoride in the treatment of osteoporosis.
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    Serum calcium and phosphate changes in thyroidectomized dogs (1969)
    Springer
    Calcified tissue international 4 (1969), S. 188-192 
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    ISSN: 1432-0827
    Keywords: Serum ; Calcium ; Phosphate ; Calcitonin ; Thyroidectomy ; Metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Après ablation des glandes thyroïdes de chiens, sans lèser les glandes parathyroïdiennes supérieurs, les taux en calcium et phosphate sériques et la gravité spécifique sont comparées avec des valeurs d'un groupe de chiens, chez lesquels une intervention simulée est réalisée. Immédiatement après thyroïdectomie, le taux de phosphate est plus élevé que le taux de calcium. Ce taux de phosphate se maintient plus longtemps à un niveau élevé que le taux de calcium, après thyroïdectomie. Le rapport entre l'augmentation du phosphate et le taux initial de phosphate sérique chez chaque animal indique des variations normales de la calcitonine d'un animal à l'autre.
    Abstract: Zusammenfassung Bei Hunden wurde die Thyreoidea entfernt, ohne die Parathyreoidea zu verletzen. Der Gehalt des Serums an Calcium und Phosphat sowie sein spezifisches Gewicht wurden mit den Werten verglichen, welche nach einer Scheinoperation bei einer Kontrollgruppe von Hunden bestimmt wurden. Unmittelbar nach der Thyreoidektomie war der Phosphatspiegel höher als jener des Calciums. Der Phosphatspiegel blieb nach der Thyreoidektomie länger hoch als der Calciumspiegel. Das Verhältnis zwischen dem Phosphatanstieg und dem Ausgangswert des Serumphosphates bei jedem Tier wies auf normale Variationen der Calcitonin-Konzentration bei verschiedenen Tieren hin.
    Notes: Abstract The thyroid glands were removed from dogs without interfering with the superior parathyroid glands. Levels of serum calcium, phosphate, and specific gravity were measured subsequently for 24 hours, and these values were compared with values obtained from a control group of dogs in which a mock operation was done. Immediately after thyroidectomy, the level of phosphate was greater than the calcium level. The phosphate level remained high longer after thyroidectomy than did the calcium level. The relationship between the increase in phosphate level and the initial serum phosphate value in each animal indicated normal variations in calcitonin levels in different animals.
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    In vitro model of aluminum-induced osteomalacia: Inhibition of hydroxyapatite formation and growth (1984)
    Springer
    Calcified tissue international 36 (1984), S. 439-441 
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    ISSN: 1432-0827
    Keywords: Osteomalacia ; Aluminum ; Hydroxyapatite ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
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    URL: http://dx.doi.org/10.1007/BF02405357
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    Studies on extractable and resistant proteoglycans from metaphyseal and cortical bone and cartilage (1981)
    Springer
    Calcified tissue international 33 (1981), S. 89-99 
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    ISSN: 1432-0827
    Keywords: Soluble proteoglycans ; Resistant proteoglycans ; Collagen ; Bone ; Cartilage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Soluble proteoglycans (SPG) were extracted from bovine (BCC) and human (HCC) costal cartilages by the dissociative method using 4 M guanidinium chloride (GuHCl). Proteoglycans which are resistant to extraction (RPG) were obtained following collagenase digestion or hydroxylamine treatment of the cartilage residues. Similarly, SPG were extracted from bovine metaphyseal and cortical bone using EDTA. The RPG were extracted from the bones using hydroxylamine. Density gradient fractionation under dissociative conditions of cartilage SPG and RPG followed by chromatography on Sepharose 2B revealed that A1D1 RPG are smaller than the SPG. SPG reacted with either collagenase or hydroxylamine are also smaller than the parent SPG. A1D1 fractions obtained from BCC-SPG and RPG or from mixtures of SPG and acid-soluble collagen are free of hydroxyproline. Hydroxyproline is not completely separated from HCC-RPG. Density gradient fractionation of bone proteoglycans and Sepharose chromatography of the A1 and A1D1 fractions showed that those obtained from metaphysis are larger than those from cortical bone. This was attributed to the presence of calcified cartilage in metaphyseal bone. The A1D1 fractions of the metaphyseal proteoglycans seemed to undergo self-association since this fraction is larger than the A1 fraction from which it is derived. Cortical bone proteoglycans do not behave similarly. Density gradient purification under dissociative conditions failed to separate hydroxyproline from the proteoglycans obtained from bone. It is hypothesized that in bone proteoglycans and collagen might be linked.
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    Oxalic acid metabolism in man: A review (1968)
    Springer
    Calcified tissue international 2 (1968), S. 115-132 
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    ISSN: 1432-0827
    Keywords: Oxalate-Calcium ; Metabolism ; Metabolic diseases ; Urinary calculi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
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    URL: http://dx.doi.org/10.1007/BF02279201
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    The incorporation and removal of large amounts of strontium by physiologic mechanisms in mineralized tissues of the rat (1968)
    Springer
    Calcified tissue international 2 (1968), S. 242-252 
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    ISSN: 1432-0827
    Keywords: Boen ; Metabolism ; Rats ; Strontium ; Tooth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'on a procédé à une étude approfondie sur l'incorporation et l'enlèvement du strontium des os et des dents de rats dans les cas de régimes alimentaires à forte et faible teneur en strontium. Dans le cas d'un régime par ailleurs en tous points satisfaisant, l'adjonction d'une quantité de strontium de masse égale à celle du calcium provoque un phénomene débilitant très severe chez le jeune rat en pleine croissance, et peut même conduire à la mort du sujet. Les effets pathogéniques du strontium ont été découverts par des méthodes utilisées seulement en recherche dans les tissus durs. L'excédent de cellules osseuses, formées à l'origine du fait de la présence de grandes quantités de strontium dans l'alimentation, se résorbe si l'on passe à un regime à faible teneur en strontium. Il apparait qu'il y a deux types d'élimination dustrontium de l'organisme: a) par excrétion, et b) par assimilation dans les tissus durs. L'on n'a plus à démontrer que le strontium s'intègre par transfert dans les incisives. L'on a également observé, chez les sujets expérimentaux aussi bien que chez ceux du groupe de vérification, que des différences dans le taux de sodium et de potassium apparaissent dans les semi-mandibules.
    Abstract: Zusammenfassung Die Einlagerung sowie die Resorption von Strontium wurde an Rattenknochen und-zähnen mittels Zugabe von niedrigen und hohen Strontiumdosen zu der Diät untersucht. Wird bei einer sonst befriedigenden Diät Calcium durch äquimolare Strontiummengen ersetzt, so entsteht eine Schwächung bei jungen wachsenden Ratten, die bis zum Tode führen kann. Die pathologischen, durch Strontium entstandenen Veränderungen wurden nur mit denjenigen Methoden verfolgt, die zur Untersuchung der harten Gewebe angewendet werden. Das Übermaß an osteoidem Gewebe, welches ursprünglich bei Zugabe großer Strontiummengen zu der Nahrung entsteht, wird in einer darauffolgenden strontiumarmen Diätperiode resorbiert. Die Resorption des Strontiums scheint an zwei physiologische Prozesse gebunden zu sein: a) Ausscheidung aus dem Organismus; b) Eingliederung in die harten Gewebe. Der Strontiumtransport in den Schneidezähnen ist bewiesen worden. Es wurden auch Unterschiede im Natrium- und Kaliumgehalt des halben Unterkiefers bei Experiment- und Kontrollgruppen beobachtet.
    Notes: Abstract The incorporation and removal of strontium from the bones and teeth of rats under conditions of low and high dietary levels of strontium were investigated. In an otherwise satisfactory diet, an amount of strontium equimolar to that of calcium seriously debilitates the young growing rat and may culminate in death. The pathology due to strontium was found by the methods used only in the hard tissues. The excess osteoid formed originally in the presence of large amounts of dietary strontium is removed during a subsequent period of feeding on a low strontium regimen. Strontium removal from participation in physiologic processes appears to be of two types, (a) excretion from the body, and (b) incarceration within the hard tissues. The translocation of strontium to the incisor teeth has been demonstrated. Differences of sodium and potassium contents of the hemi-mandibulae of the experimental and control groups were also observed.
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    Mineral deposition in collagenin vitro (1968)
    Springer
    Calcified tissue international 2 (1968), S. 343-352 
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    ISSN: 1432-0827
    Keywords: Nucleation ; Mineralization ; Bone ; Collagen ; Apatite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Nous avons utilisé de la collagène d'os de mounton et de tendons de queues de rats et des cristaux d'apatite pour étudier dans un système modèle la catalysation de la nucléation et la déposition de minéral dans un tampon métastabile. La collagène d'os de mouton se trouvait être un bon catalysateur, tandis que des expériences antérieures ont démontré que la collagène de tendons de queues de rats était un catalysateur très faible. Le phase rapide de la déposition de l'apatite dans la collagène se termine aussitôt que le contenu du minéral a attaint au plus 50 à 60 pour cent, bien que la supersaturation du tampon est encore bien èlevée. Les résultats montrent que dans un tel système modèle la quantité du depôt minéral est réglée par des facteurs semblables à ceux qui opèrent pendant la calcification biologique.
    Abstract: Zusammenfassung Kollagen aus Schafsknochen und Rattenschwanzsehnen und Apatitkeime wurden verwendet in einem Modell-System zur Untersuchung der katalytischen Nukleation und der Fällung von Mineral in einem metastabilen Calciumphosphatpuffer. Kollagen aus Schafsknochen war ein guter Katalysator für die Nukleation, während in früheren Versuchen sich herausstellte, daß Rattenschwanzkollagen ein ganz schlechter Katalysator ist. Die schnelle Phase der Apatitfällung im Kollagen war beendet, wenn der Mineralgehalt bis zu 50–60% angestiegen war, obwohl der Puffer noch stark übersättigt war. Die Resultate weisen daraufhin, daß die Menge des gefällten Minerals in einem solchen Modell-System von ähnlichen Faktoren reguliert wird wie die biologische Verkalkung.
    Notes: Abstract Sheep bone collagen, rat tail tendon collagen and apatite seeds were used in a model system to study nucleation catalysis and mineral deposition in a metastable calcification buffer. Sheep bone collagen was shown to be a good nucleation catalyst, while earlier experiments have shown that rat tail tendon collagen was a very poor catalyst. The rapid phase of apatite deposition in the collagen was terminated as soon as a mineral content of not more than 50–60 per cent was reached, although the buffer was still highly supersaturated. The results suggest that the amount of mineral deposited in such a model system is regulated by factors similar to those operating in biological calcification.
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    A structural basis for the transphosphorylation of nucleotides with hydroxyapatite (1969)
    Springer
    Calcified tissue international 3 (1969), S. 284-292 
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    ISSN: 1432-0827
    Keywords: Hydroxyapatite ; Pyrophosphate ; Nucleotides ; Adenosine triphosphate ; Transphosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La base de la transphosphorilation entre les nucléotides et l'hydroxyapatite (HA) est explorée. Utilisant un recent modèle de la surface de HA et de la structure de polyphosphates de 2 et 3 parties, une raisonnable explication atomique peut être montrée pour cette réaction. La transphosphorilation a produit un pyrophosphate sur HA qui est différent du pyrophosphate absorbé sur HA de la solution. Les modèles suggèrent que la distinction est dûe à une orientation différente du pyrophosphate sur la surface de HA dépendant de l'origine du pyrophosphate.
    Abstract: Zusammenfassung Es wurde die Grundlage für die Transphosphorylierung zwischen Nukleotiden und Hydroxy-Apatit (HA) untersucht. Eine plausible atomare Darstellung dieser Reaktion ist möglich, wenn man kürzlich vorgeschlagene Modelle der Oberfläche von HA und der Struktur von zwei- und dreigliedrigen Polyphosphaten benutzt. Man findet dann, daß Transphosphorylierung zu einem Pyrophosphat des HA führt, welches von dem Pyrophosphat, welches HA aus der Lösung absorbiert, unterschieden werden kann. Auf Grund der Modelle kann man annehmen, daß dieser Unterschied auf einer unterschiedlichen Orientierung des Pyrophosphats auf der Oberfläche des HA beruht, welche wiederum von der Herkunft des Pyrophosphats abhängt.
    Notes: Abstract The basis for transphosphorylation between nucleotides and hydroxyapatite (HA) has been explored. Using a recently-proposed model for the surface of HA and the structure of 2- and 3-membered polyphosphates, a reasonable atomic explanation can be shown for this reaction. Transphosphorylation has been found to result in a pyrophosphate on HA which is distinctive from pyrophosphate absorbed onto HA from solution. The models suggest that this distinction is due to a different orientation of the pyrophosphate on the surface of the HA depending on the origin of the pyrophosphate.
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    Adult human enamel (1969)
    Springer
    Calcified tissue international 3 (1969), S. 308-317 
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    ISSN: 1432-0827
    Keywords: Bone ; Enamel ; Hydroxyapatite ; X-ray Diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'objet de cette étude a été de déterminer l'effet du mode de préparation (par meulage) sur la largeur des raies de diffraction de l'émail. La préparation d'émail, par meulage, en utilisant divers procédés ainsi qu'une pièce à main dentaire conventionnelle provoque un élargissement des pics obtenus (002, 211, 200 et 202) lorsqu'on la compare avec de la poudre d'émail, obtenue par meulage à l'aide de billes. L'élargissement des raies n'est pas observé lorqu'un monocristal d'hydroxylapatite est meulé à l'aide d'un diamant fin. En général, l'élargissement est moins important, lorsque le meulage est effectué à l'aide de turbines dentaires. L'importance du meulage dépend de façon variable d'un ou plusieurs des facteurs suivants: rugosité des instruments coupants, vitesse de meulage, direction de meulage, et la présence ou l'absence d'eau. Le meulage prolongé par billes de l'émail provoque aussi un élargissement dans les mêmes conditions, cependant, l'os n'est pas endommagé. Ces résultats indiquent que l'émail est plus sensible que l'hydroxylapatite et l'os. L'élargissement de raies peut être dû soit à une déformation de la maille cristalline, soit à une diminution de taille des cristaux.
    Abstract: Zusammenfassung Es wurde eine Untersuchung durchgeführt, um den Einfluß der Probenvorbereitung (Zerreibungsmethode) auf die Breite des Linienprofil-Querschnittes von Zahnschmelz zu bestimmen. Gewinnung von Zahnschmelz mit den verschiedenen Schneidinstrumenten einer konventionellen Bohrmaschine verursachte eine Verbreiterung aller untersuchten Peaks (002, 211, 200 und 202) im Vergleich zum gleichen Schmelz, der mit dem Rosenbohrer zerrieben wurde. Eine Verbreiterung der Linie konnte nicht beobachtet werden, wenn ein einzelner Kristall von Hydroxyapatit mit einem ganz feinen Diamanten zerrieben wurde. Im allgemeinen war die Verbreiterung weniger ausgesprochen, wenn die hochtourige Bohrtechnik zur Anwendung kam. Das Ausmaß der Verbreiterung, das durch Zahnbohrer verursacht wurde, war abhängig von einem oder mehreren der folgenden Faktoren: Rauheit des Schneidinstrumentes, Zerreibungsgeschwindigkeit, Zerreibungsrichtung und das Vorhandensein oder Fehlen von Wasser. Verlängerte Zerreibung von Schmelz mit dem Rosenbohrer verursachte ebenfalls eine Verbreiterung. Unter identischen Bedingungen blieb der ausgeglühte Knochen jedoch unversehrt. Diese Beobachtungen zeigen, daß Schmelz für Zerreibungsschäden anfälliger ist, als Hydroxyapatitkristalle oder ausgeglühter Knochen. Die eigentliche Ursache der Linienverbreiterung kann entweder eine Schädigung infolge Distortion des Gitters oder eino Reduktion der Größe der individuellen Kristalle sein.
    Notes: Abstract A study was conducted to determine the effect of sample preparation (grinding method) upon breadth of the diffraction profile of enamel. Collecting enamel by grinding with various cuttin tools in the low-speed dental handpiece caused broadening of all peaks (002, 211, 300 and 202) examined, compared to ball, ground, counter-part enamel. Line broadening was not observed when a single crystal of mineral hydroxyapatite was ground with a very fine diamond. In general, broadening was less pronounced with the high-speed air turbine technique. The amount of broadening caused by dental burs depended upon one or more of the following factors: coarseness of cutting instrument, grinding speed, grinding direction, and the presence or absence of water. Prolonged ball grinding of enamel also caused broadening; under identical conditions, however, annealed bone remained undamaged. These findings indicate that enamel is more sensitive to grinding damage than the mineral hydroxyapatite crystal or annealed bone. The actual cause of line broadening may be either strain due to lattice distortions or a reduction in size of individual crystallites.
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    Fluoride and bone (1969)
    Springer
    Calcified tissue international 3 (1969), S. 1-16 
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    ISSN: 1432-0827
    Keywords: Fluoride ; Metabolism ; Toxicity ; Action ; Therapeutics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
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    Effects of pyrophosphate and diphosphonates on the dissolution of hydroxyapatites using a flow system (1980)
    Springer
    Calcified tissue international 31 (1980), S. 153-159 
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    ISSN: 1432-0827
    Keywords: Hydroxyapatite ; Dissolution ; Pyrophosphate, Diphosphonates ; Calcium ; Phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Pyrophosphate and diphosphonate ions have been said to diminish the dissolution of hydroxyapatite crystals, because they lower the equilibrium concentrations of calcium and phosphate ions in the bulk solution around hydroxyapatite crystals in a closed system. However, in a closed system these effects are not necessarily due to an effect on dissolution alone. In this paper we have used a continuous flow system to study the effects of pyrophosphate and two diphosphonates, ethane-1-hydroxy-1,1-diphosphonate and dichloromethane diphosphonate, on the dissolution of hydroxyapatite. All three compounds decreased markedly the rate of dissolution of hydroxyapatite as well as the exchangeable pools of calcium and phosphate ions around the cystals.
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    Studies on the structure and chemistry of dentin collagen-phosphophoryn covalent complexes (1980)
    Springer
    Calcified tissue international 31 (1980), S. 123-134 
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    ISSN: 1432-0827
    Keywords: Phosphophoryn ; Collagen ; Dentin cross-linking ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Bovine and rat dentin contain aspartylphosphoseryl-enriched collagen-associated phosphoproteins which represent 1–2% of the mineral-free dry weight. These phosphophoryn moieties are not extracted by saturated neutral EDTA, pH 7.4, nor by guanidine hydrochloride-EDTA, pH 7.4. Cyanogen bromide degradation of the dentin matrix does release a high molecular weight fragment containing hydroxyprolyl, hydroxylysyl, prolyl, and glycyl residues as well as high concentrations of aspartyl and phosphoseryl residues, the amounts of which indicate a 50% collagen-50% phosphophoryn nature. Gel filtration and ion exchange chromatography under dissociative, denaturing conditions, as well as in the presence of disulfide bond reducing reagents failed to separate the collagen and phosphophoryn moieties. Hydroxyapatite, which selectively absorbs phosphophoryn, also failed to separate the collagenous component, leading to the conclusion that the moieties represented a covalent conjugate.31P NMR spectroscopy showed the bovine collagen-phosphophoryn complex to contain only phosphomonoesters similar to soluble phosphophoryn. Reduction with [3H]NaBH4, followed by cross-link analysis, did not reveal any reduced aldimine cross-link amino acids. Of the 4 hydroxylysyl residues/1000 in the intact bovine collagen-phosphophoryn complex, one-fourth are periodate resistant, indicating either O-or N-substitution. The periodate-resistant hydroxylysyl residues are located in bacterial collagenase-sensitive regions, and it is likely that these represent hydroxylysine O-glycosides. These data suggest that: (a) the collagenous component of the conjugate derives from a glycosylated peptide, probablyα2CB4, and (b) the association is covalent, but does not involve disulfides, phosphate-, hydroxylysine-, or reducible aldehyde-mediated covalent bonds.
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    Piezoelectricity in collagen films (1980)
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    Calcified tissue international 31 (1980), S. 257-259 
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    ISSN: 1432-0827
    Keywords: Piezoelectricity ; Collagen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Tissue collagen exhibits several levels of structural organization, and this complicates efforts to determine the origin of its piezoelectricity. We made collagen films—by evaporation and electrodeposition from solution—and examined the relation between collagen's piezoelectricity and its electron microscopic appearance. We found that the electrodeposited films were more organized and exhibited higher piezoelectric coefficients than the evaporated films. Despite this, the evaporated films were piezoelectric, thereby suggesting that the effect originates either at the level of the tropocollagen molecule or, at most, with aggregated structures no larger than 50 Å in diameter.
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    Binding of the bone-seeking agent99mTc-1-hydroxyethylidene-1,1-diphosphonic acid to cartilage and collagen in vitro and its stimulation by Er3+ and low pH (1980)
    Springer
    Calcified tissue international 32 (1980), S. 91-94 
    Details
    ISSN: 1432-0827
    Keywords: Diphosphonates ; Cartilage ; Collagen ; Erbium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The bone-seeking agent99mTc-labeled 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) unexpectedly binds to particles of human articular cartilage as well as cortical bone in vitro. Collagen also sequesters this compound, suggesting that collagen contributes to the uptake of99mTc-HEDP by cartilage and bone. Particles of the bone mineral calcium hydroxyapatite also bind99mTc-HEDP in vitro. Pretreatment of particles with Er3+ stimulates binding in each case. Lowering the pH of incubation to pH 2 has this effect for bone, cartilage, and collagen, but not for calcium hydroxyapatite. Mechanisms additional to the simple ionic attraction between the phosphonate groups of HEDP and metal cations such as Ca2+ are responsible for the uptake of99mTc-HEDP by body tissues.
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    X-ray diffraction analysis of transversal osteonic lamellae (1983)
    Springer
    Calcified tissue international 35 (1983), S. 279-283 
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    ISSN: 1432-0827
    Keywords: Osteon ; Lamella ; Hydroxyapatite ; X-ray diffraction ; Polarizing microscope ; Microradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary When isolated osteon samples are submitted to wide-angle X-ray diffraction, it is not possible to detect any preferential orientation of the hydroxyapatite crystallites of the lamellae with transversally arranged fiber bundles. So a complete and exhaustive X-ray diffraction analysis of an osteon needs adequately prepared osteonic subunits. For the present investigation, 2 types of samples were prepared from longitudinal and alternate osteons: osteonic radial sections and isolated straightened transversal lamellae. An X-ray diffraction microcamera has been used with a rotating anode X-ray generator. In accordance with the data provided by the polarizing microscope, the orientation of crystallites runs parallel to the osteon axis in longitudinally structured osteons, whereas in alternate osteons the orientation changes by about 90° in successive lamellae. Neither crystallites associated with the collagen fibrils that run alongside the osteocyte canaliculi nor those associated with the fibrils that run transversally in longitudinally structured osteons are revealed by X-ray diffraction, because there are so few of them.
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    URL: http://dx.doi.org/10.1007/BF02405046
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    Ultrastructural cytochemistry of complex carbohydrates in osteoblasts, osteoid, and bone matrix (1983)
    Springer
    Calcified tissue international 35 (1983), S. 309-319 
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    ISSN: 1432-0827
    Keywords: Calcification ; Glycosaminoglycan ; Glycoprotein ; Collagen ; Acid phosphatase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Glycosaminoglycans (GAGs) and glycoproteins are essential components for osteogenesis. We have examined rat osteoblasts, osteoid, transitional zone, and fully calcified bone matrix, utilizing Spicer's high-iron diaminethiocarbohydrazide-silver protein (HID-TCH-SP) method for sulfated glycoconjugates and Thiéry's periodate-TCH-SP (PA-TCH-SP) method for vicinal glycol-containing glycoconjugates. HID-TCH-SP stained cytoplasmic granules of osteoblasts. Stain deposits in the extracellular matrix were observed in decreasing amounts in osteoid, the transitional zone, and fully calcified bone matrix. Enzyme digestion with testicular hyaluronidase removed most HID-TCH-SP stain deposits. PA-TCH-SP staining was observed with increasing intensity in rough endoplasmic reticulum, Golgi saccules, and cytoplasmic granules. Collagen fibrils in osteoid were weakly stained with PA-TCH-SP, and their staining appeared even weaker in fully calcified bone matrix. In contrast, collagen fibrils in calcified cartilage stained intensely with the PA-TCH-SP method. Focal circular profiles (0.1–0.5µm in diameter), which lacked collagen fibrils but reacted moderately with PA-TCH-SP, were frequently seen in the transitional zone and fully calcified bone matrix, but were only occasionally present in osteoid. The presence of testicular hyaluronidase-resistant GAG and acid phosphatase in these focal areas suggests that they represent sites of GAG degradation. The eventual loss of HID-TCH-SP staining in the bone matrix suggests that removal of sulfated glycoconjugates may be a requisite for expansion of initial calcification sites and/or complete calcification.
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    Studies of the intercellular matrix of growth plates from dwarf and homozygous nonaffected alaskan malamutes: Collagen and hexosamine (1980)
    Springer
    Calcified tissue international 32 (1980), S. 237-245 
    Details
    ISSN: 1432-0827
    Keywords: Growth plate ; Dwarf ; Collagen ; Hexosamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary This study was performed to compare the extractability of dwarf growth plate collagen and hexosamine with that of homozygous nonaffected Malamutes and to measure the activity of three of the enzymes involved in the post-translational modifications of the collagen molecule. No significant differences were found in the activity of prolyl hydroxylase or lysyl oxidase in the dwarf growth plates. Lysyl hydroxylase activity in the dwarf was decreased to 22% and 33% that of the activity present in the homozygous nonaffected growth plates. Amino acid analysis of the collagen isolated from dwarf growth plates failed to reveal any decrease in hydroxylysine content. Growth plates were extracted with either 1 M sodium chloride or 4 M guanidine hydrochloride. The extracts were applied to a DEAE-cellulose column. Amino acid analyses of the material which did not bind to DEAE revealed a slight decrease in the amount of guanidine-extractable hydroxyproline in the dwarf but a 60-fold increase in the amount of salt-extractable hydroxyproline in the dwarf growth plates. Material which eluted with 1 M sodium chloride was analyzed for hexosamine. There was a 10-fold increase in the amount of salt-extractable hexosamine present in the dwarf growth plates, whereas no significant differences were observed in the guanidine-extracted material. Hexosamine analysis of the growth plates revealed a significant increase in the total amount of hexosamine present in the dwarf growth plates. SDS-polyacrylamide gels of the material which did not bind to DEAE as well as the pepsin digested, 0.9M sodium chloride precipitated collagen demonstrated the presence of only type II collagen.
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    Solubility of calcium salts, enamel, and hydroxyapatite in aqueous solutions of simple carbohydrates (1984)
    Springer
    Calcified tissue international 36 (1984), S. 64-71 
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    ISSN: 1432-0827
    Keywords: Solubility of calcium salts ; Enamel ; Hydroxyapatite ; Carbohydrates ; Complex formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The solubility of various Ca(II) salts, hydroxyapatite, and powdered human dental enamel in the presence of simple carbohydrates was studied by determining the complex strength between Ca(II) and the carbohydrates. In 1.0m CaSO4, the following simplified sequence of complex strengths was obtained for the more common carbohydrates: Na-citrate〉d-sorbitol〉xylitol〉d-mannitol〉d-fructose〉d-glucose〉d-xylose. Whereas the more soluble Ca(II) compounds (like CaSO4) exerted measurable complexation with xylitol, no such complexation was found with hydroxyapatite and enamel powder. This also concerned other alditols. Calculation of the stability constants (K) showed sorbitol (K=0.81 M) and xylitol (K=0.67m) to form stronger complexes in saturated CaSO4 than other alditols. The most suitable coordination site appeared to be a vicinalcis-cis-triol. Precipitation studies showed that 0.5m xylitol and 0.5 M sorbitol significantly retarded the formation of calcium phosphate precipitates from a solution of Ca(II) and phosphate, compared with the effect caused by glucose, sorbose, or xylose. The effect caused by xylitol and sorbitol was explained in terms of partial displacement of water molecules in the primary hydration layer of Ca(II) ions, caused by competition between polyol and water molecules. In the presence of aldoses and ketoses, virtually instantaneous precipitation occurred. These results suggest that open-chain alditols may influence the chemical reactions of Ca(II) in plaque, saliva, and caries lesions. Alditols do not function as demineralizing agents of the teeth, however. Through the retarding effect on calcium phosphate precipitation, alditols may favorably govern remineralization of carious lesions.
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    Silicon: A requirement in bone formation independent of vitamin D1 (1981)
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    Calcified tissue international 33 (1981), S. 27-34 
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    ISSN: 1432-0827
    Keywords: Silicon ; Skull formation ; Vitamin D ; Collagen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Silicon has been reported to be involved in an early stage of bone formation as a result of earlier in vitro and in vivo studies in this laboratory. It is now possible to demonstrate that silicon exerts an effect on bone formation independent of the action of vitamin D. Day-old cockerels were fed Sideficient and Si-supplemented diets with adequate and no dietary vitamin D under trace element controlled conditions. At the end of 4 weeks chicks receiving dietary vitamin D3 (600 IU) exhibited optimal rates of growth whereas the growth rates of chicks receiving D2 (6000 IU) and no vitamin D were markedly depressed. There were no significant differences between growth of Si-deficient and Si-supplemented chicks on the same level of vitamin D. Skull and bone size was proportional to overall chick growth. However, all chicks on Sideficient diets irrespective of the level of dietary vitamin D had gross abnormalities of skull architecture, the overall skull appearance being narrower and shorter. The frontal area was narrower and the dorsal median line at the front parietal junction was depressed with a narrowing both posterior and laterally, stunting parietal and occipital areas. These abnormal areas showed fewer trabeculae and less calcification. Analyses of skull frontal bones for hexosamine, collagen, noncollagenous protein, and bone mineral demonstrated that the major difference was in collagen content, the Si-deficient skulls showing considerably less collagen at each level of vitamin D. These findings demonstrate that silicon has a significant effect on the bone matrix independent of vitamin D, and support the earlier postulate that silicon is involved in an early stage of bone formation.
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    Density of a sample bovine cortical bone matrix and its solid constituent in various media (1981)
    Springer
    Calcified tissue international 33 (1981), S. 499-504 
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    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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    Chemical aspects of the matrix concept in calcified tissue organisation (1968)
    Springer
    Calcified tissue international 2 (1968), S. 1-19 
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    ISSN: 1432-0827
    Keywords: Collagen ; Hydroxyapatite ; Keratin ; Enamel ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
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    URL: http://dx.doi.org/10.1007/BF02279189
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  • 40
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    The effect of ascorbic acid on the glycolytic and respiratory metabolism of embryonic chick tibias (1968)
    Springer
    Calcified tissue international 2 (1968), S. 77-82 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Metabolism ; Ascorbic Acid ; Tissue Culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Du tissu osseux, cultivé pendant 5 jours dans un milieu chimiquement défini, présente une augmentation de la consommation en O2 et une diminution de la production d'acide lactique lorsqué de l'acide lactique (50 μg/mI) est présent dans le milieu de culture. Ces paramètres ont été mesurés pendant des incubations de courte durée, en cultures de tissus. En n'ajoutant de l'acide lactique qu'au dernier jour de culture ou pendant les 4 premiers jours, et non le dernier jour, les valeurs en O2 et en acide lactique sont identiques à celles observées lorsque la vitamine est présente pendant 5 jours. Des produits similaires à l'acide ascorbique (50 μg/ml), administrés pendant 5 jours donnent des résultats identiques à ceux de la vitamine C. Une expérience préliminaire pour évaleur la vitesse d'oxydation de l'acide ascorbique dans le milieu de culture a permis de montrer que la vitamine doit être remplacée quotidiennement lorsque les cultures sont traitées avec 20% d'O2 et plus fréquemment avec des concentrations d'O2 plus élevées. Les changements dans le métabolisme énergétique, liés à l'acide ascorbique et observés dans cette étude, indiquent que la vitamine pourraît être un facteur important de stimulation du métabolisme squelettique aérobique.
    Notes: Abstract Bones cultured for 5 days in a chemically defined medium showed an increased O2 consumption and decreased lactic acid production when ascorbic acid (50 μg/ml) was present in the culture medium. In this and the following experiments these parameters were measured in short-term incubations following tissue culture. Adding ascorbic acid for only the final day of culture or for the first 4 days and not the final day gave O2 and lactic acid results similar to those obtained when the vitamin was present for all 5 days. Ascorbic acid analogs (50 μg/ml) added for 5 days also exhibited results similar to those for vitamin C. A preliminary experiment to evaluate the oxidation rate of ascorbic acid in the culture medium established that the vitamin must be replenished daily when cultures are gassed with 20% O2 and more frequently with higher O2 concentrations. The ascorbic acid-dependent changes in energy metabolism seen in this study suggest that the vitamin may be an important factor in stimulating skeletal aerobic metabolism.
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    Incorporation and release of85Sr and14C-proline-hydroxyproline in mineral and collagen of bone and incisor teeth of growing rats (1968)
    Springer
    Calcified tissue international 2 (1968), S. 106-110 
    Details
    ISSN: 1432-0827
    Keywords: Collagen ; 14C-Proline ; Growth ; Bone ; Teeth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Zusammenfassung Das Ausmaß, bis zu welchem Austausch- und Wiederverwendungsprozesse der mineralen Tracer die Messungen des mineralen Skelett-Auf- und Abbaues beeinflussen können, wurde ausgewertet; zu diesem Zweck wurde die Geschwindigkeit des Auftretens und Verschwindens von85Sr und von14C-Prolin-Hydroxyprolin in Knochen und Zähnen von wachsenden Ratten während der 12 auf die simultane parenterale Injektion dieser Tracer folgenden Tage verglichen. Der Ausdruck für die relative Geschwindigkeit des Kollagen-Auf- und Abbaues, bei welchem im Gegensatz zum Mineralmetabolismus kein Mitwirken des Austauschphänomens vermutet wird, basiert auf der Umwandlung von14C-Prolin zu14C-Hydroxyprolin; die spezifische Aktivität des letzteren wurde bestimmt. Aus der spezifischen Aktivität des Minerals sowie jener des Kollagens konnten die Geschwindigkeit und die Art des Wachstums der untersuchten Proben ersehen werden, d.h.schnelles Wachstum und ein kurzes Zeitintervall zwischen Bildung und Resorption des Gewebes imKnochen der Metaphyse, die auch die knorpelige Wachstumsplatte enthält, und andererseitslangsames Wachstum und längeres Zeitintervall (länger als die 12 Tage des Experimentes) zwischen Bildung und Resorption des Gewebes imKnochen der Diaphyse und in den Schneidezähnen. Immerhin fiel die spezifische Aktivität des Kollagen/Mineral-Anteils im Knochen der Metaphyse während dem 4–12tägigen Zeitintervall auf die Hälfte, im Gegensatz zum Knochen der Diaphyse und der Schneidezähne, bei welchen während dieser Zeitspanne kein Unterschied in diesem Verhältnis beobachtet wurde. Diese Ergebnisse zeigen, daß Kollagen in der Wachstumszone der Metaphyse durch Resorption verschwindet, bevor es ganz mineralisiert ist, und daß der Austausch ein relativ unwichtiger Faktor in der Kinetik auf lange Sicht des Knochenminerals ist.
    Notes: Abstract The extent to which exchange and reutilization processes of mineral tracers affect skeletal mineral accretion and resorption measurements was evaluated by comparing the rates of appearance and disappearance of85Sr and14C-proline-hydroxyproline in bones and teeth in growing rats for 12 days following simultaneous parenteral injection of these tracers. Expressions for the relative rates of collagen synthesis and breakdown, which unlike mineral metabolism are considered not to be complicated by exchange phenomena, were based on14C-proline conversion to14C-hydroxyproline; the specific activity of the latter was determined. Both the mineral and the collagen specific activities reflected the rates and patterns of growth of the samples assayed; rapid growth and a short interval of time between formation and resorption of tissue in themetaphyseal bone which contains the cartilagineous growth plate, slow growth and an interval of time between formation and resorption of tissue indiaphyseal bone and incisor teeth which is longer than the 12 days of the experiment. However, in metaphyseal bone the specific activity collagen/mineral ratio dropped by one half during the 4–12 day interval in contrast to diaphyseal bone and incisor teeth in which no change in this ratio was observed during this period of time. The data indicate that collagen in the metaphyseal growth zone is removed by resorption before it has become fully mineralized, and that exchange is a relatively unimportant factor in the long term kinetics of bone mineral.
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    The environment of calcified components in keratins (1968)
    Springer
    Calcified tissue international 2 (1968), S. 361-369 
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    ISSN: 1432-0827
    Keywords: Calcification ; Hydroxyapatite ; Keratin ; Hair ; Electron diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Certaines régions du cortex des fibres de kératine contiennent une proportion relativement élevée de matériel non kératinisé. L'orientation microfibrillaire dans ces régions est biaxiale et on y trouve, en outre, des zones de matériel amorphe. Les sels calciques, et en particulier l'hydroxyleapatite, sont étudiés par diffraction électronique qui permet de les localiser et de les identifier. En outre, cette technique permet de déterminer la fréquence de cellules nonkératinisées dans la partie interne du cortex et de les comparer avec les propriétés histochimiques de cette région. Une comparison est effectuée entre la calcification de la kératine et celle intéressant le collagène et l'élastine.
    Abstract: Zusammenfassung Es wird gezeigt, daß Bereiche im Cortex von gewissen Keratinfasern einen relativ hohen Anteil an nichtkeratinösem Material enthalten. Ferner konnte nachgewiesen werden, daß die Orientierung der Mikrofibrillen in diesen Bereichen biaxialer Art ist, und daß Bezirke von amorphem Material vorhanden sind. Die Calciumsalze und insbesondere das Hydroxyapatit konnten mit Hilfe der Elektronendiffraktion lokalisiert und identifiziert werden. Diese Methode hat sich auch als wertvoll erwiesen, um die Wechselbeziehung zwischen dem Vorkommen von einigen nichtkeratinisierten Zellen im Cortexinnern und den histochemischen Eigenschaften dieser Regionen zu zeigen. Ein Vergleich wird gemacht zwischen der Umgebung der Verkalkungsstellen im Keratin mit derjenigen im Kollagen und im Elastin.
    Notes: Abstract Regions in the cortex of some keratin fibres are shown to contain a relatively high proportion of non-keratinous material. The microfibrillar orientation in these regions is shown to be biaxial in nature and, in addition, areas of amorphous material are reported. Calcium salts, in particular hydroxyapatite, have been located and identified using electron diffraction, which has also proved valuable in correlating the incidence of some non-keratinised cells in the inner part of the cortex with the histochemical properties of this region. A comparison is made between the environment of the sites of calcification in keratin with those in collagen and elastin.
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    Effect of disuse osteoporosis on bone composition: the fate of bone matrix (1968)
    Springer
    Calcified tissue international 2 (1968), S. 20-29 
    Details
    ISSN: 1432-0827
    Keywords: Bone Atrophy ; Bone Resorption ; Calcium ; Collagen ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Atrophie osseuse d'immobilisation était induite par section de la plexus brachial et/ou désarticulation de la coude. Après 9 bis 12 semaines de désuétude huméri intactes furent examinés par rayons X et leur qualités physiques déterminés. Les humérientiers furent isolés, dégraissés, desséchés au poids constant, et leur teneur en cendre d'os et collagène déterminés. Huit des 10 huméri immobilisés monstrérent radiodensité diminué. La jambe inusitée monstra perte parallèle en poids sec et poids sans gras (−23.2%), en collagène (−25.3%), et en cendre d'os (−26.1%) en comparaison de la jambe normale. Les données monstrèrent que la portion plus grande du tissu osseux perdu en atrophie osseuse d'immobilisation est remplacée par de l'eau, du gras, et des autres matériels organiques inconnus plutôt que par tissu fibreux, et que collagène est perdu en proportion du minéral. La perte proportionellement plus grande du collagène et de la cendre d'os que du poids sec et poids san gras semble dû à une augmentation du matériel organique, non-collagéne, non-lipide, kprobablement protéine.
    Abstract: Zusammenfassung Immobilisations-Knochenatrophie wurde in 10 erwachsenen Hunden herbeigeführt durch Brachialplexusschnitt und/oder Ellenbogenexartikulation. Nach 9–12 Wochen der Immobilisation wurden die intakten Humeri unter Röntgenstrahlen untersucht und ihre physischen Eigenschaften bestimmt. Derintakte Humerus wurde isoliert, entfettet, zu konstantem Gewicht getrocknet und der Knochenaschengehalt und Kollagengehalt bestimmt. Acht der 10 experimentellen (immobilisierten) Humeri demonstrierte Beweis von verringerter Röntgendichte. Die immobilisierte Extremität zeigte ähnlichen Verlust in trockenem, fettfreiem Gewicht (−23,2%) in Kollagen (−25.3%) und Knochenasche (−26,1%) im Vergleich zur normalen Extremität. Die Date deuten an, daß der Hauptanteil des Verlustes des Knochengewebes (bei Immobilisations-Knochenatrophie) von Wasser, Fett und anderen unidentifizierten organischen Substanzen ersetzt wird, als von Faserngewebe und daß Kollagen und Knochenasche im gleichen Verhältnis verloren gehen. Der größere, proportionale Verlust an Kollagen und Knochenasche, eher als der Verlust an fettfreiem Gewicht, scheint in der Zunahme an nicht kollagener, nicht lipoider, organischer Substanz, vermutlich Protein, zu liegen.
    Notes: Abstract Disuse bone atrophy was induced in 10 adult dogs by means of brachial plexus section and/or elbow disarticulation. After 9 to 12 weeks of disuse intact humeri were examined by X-ray, and their physical properties determined. Thewhole humeri were isolated, defatted, dried to constant weight, and their mineral and collagen content determined. Eight out of 10 experimental (non-used) humeri demonstrated evidence of decreased radiodensity. The non-used limb demonstrated parallel loss in dry, fat-free weight (−23.2%), in collagen (−25.3%), and in mineral (−26.1%), as compared to the normal limb. The data indicated that the major portion of the lost bone tissue in disuse osteoporosis is replaced by water, fat, and other unidentified organic materials rather than fibrous tissue, and that collagen is lost in equal proportion to mineral. The proportionatelly greater loss of collagen and mineral than of dry, fat-free weight appears to be due to an increase of non-collagenous, non-lipid organic material, presumably protein.
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    Experimental factors that influence collagen calcificationin vitro (1968)
    Springer
    Calcified tissue international 2 (1968), S. 214-228 
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    ISSN: 1432-0827
    Keywords: Calcinosis ; Calcification ; Cartilage ; Collagen ; Mineral metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les facteurs, influençant la vitesse et l'intensité du phénomène d'association des ions calcium et phosphates avec des fibres contenant du collagène, et préparés à partir du tendon de boeuf par deux méthodes d'extraction différentes, ont été étudiés. Les fibres, obtenues par ces deux méthodes, nécessitent spécifiquement du phosphate pour absorber du calcium et vice versa. L'absorption ionique des deux préparations est inhibée par du Mg++, du pyrophosphate et un peptide acidique, isolé du sérum humain. Alors que les fibres contenant du collagène, préparées selon les deux méthodes, présentent une absorption ionique à des vitesses sensiblement identiques, seule une des méthodes donne une matrice réagissant positivement à la technique de coloration au nitrate d'argent de von Kossa. Etant donné que les deux critères de calcification sont intéressés de façon identique par des conditions de réaction et par des inhibiteurs, il apparait que les deux facteurs sont des manifestations de différents stades de calcification et que des études d'absorption ionique fournissent une base quantitative d'appréciation de la calcification, pouvant être d'importance pour l'étude du mécanisme et de contrôle de la minéralisation tissulaire.
    Abstract: Zusammenfassung Überprüft wurden die Faktoren, welche Geschwindigkeit und Ausmaß der Erscheinung beeinflussen, wobei Calcium- und Phosphationen sich mit den kollagenhaltigen, durch zwei verschiedene Extraktionsmethoden aus Rindersehnen gewonnenen Fasern eng zusammenbinden. Die mit beiden Methoden zubereiteten Fasern benötigen spezifisch Phosphat für die Calciumaufnahme und Calcium für die Phosphataufnahme. Die Ionenaufnahme beider Arten wird durch Mg++, Pyrophosphat und saure, aus dem menschlichen Serum isolierte Peptide gehemmt. Während die nach beiden Methoden präparierten kollagenhaltigen Fasern eine Ionenaufnahme von beinahe gleicher Geschwindigkeit verursachen, ergibt nur eine dieser Methoden eine Matrix, die mit der Silbernitratfärbung nach vonKossa positiv reagiert. Da beide Calcifikationskriterien gleicherweise durch Reaktionsbedingungen und Inhibitoren beeinflußt werden, wird daraus geschlossen, daß beide Erscheinungen verschiedener Stadien des Gesamtcalcifikationsprozesses sind. Untersuchungen über die Ionenaufnahme ergeben eine quantitative Angabe der Verkalkung, welche für die Erforschung des Mechanismus und der Kontrolle der Mineralisation der Gewebe wichtig sein könnte.
    Notes: Abstract Factors that influence the rate and extent of the phenomenon in which calcium and phosphate ions become firmly associated with collagen-containing fibers prepared from beef tendon by two different extraction methods have been investigated. The fibers produced by both methods specifically require phosphate for calcium uptake and calcium is required for phosphate uptake. Ion uptake by both types is inhibited by Mg++, pyrophosphate, and an acidic peptide isolated from human serum. Whereas the collagen-containing fibers prepared by both methods induce ion uptake at nearly identical rates, only one of the methods produced a matrix that gives a positive response to the silver nitrate staining technique of von Kossa. Since both criteria of calcification are similarly influenced by reaction conditions and inhibitors, it is concluded that both are manifestations of different stages of the overall calcification process and that studies of ion uptake provide a quantitative assessment of calcification which could be of importance for investigating the mechanism and control of tissue mineralization.
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    Effects of vitamin D metabolites and analogs on bone collagen synthesis in vitro (1982)
    Springer
    Calcified tissue international 34 (1982), S. 103-110 
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    ISSN: 1432-0827
    Keywords: Bone ; Collagen ; Vitamin D metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of selected vitamin D3 metabolites and analogs on bone collagen synthesis in vitro were examined in organ cultures of neonatal mouse calvarial bone. The incorporation of [3H]proline into the collagenase-digestible fraction of newly synthesized protein was progressively inhibited by 1α,25-dihydroxyvitamin D3 (1α,25-(OH)2D3) (10−12 M to 10−7 M) in 24-h cultures, and incorporation into noncollagen protein was also blunted at the higher doses employed. The synthetic analog 1α-hydroxyvitamin D3 (1α-OHD3) was almost 300-fold less potent an inhibitor of collagen synthesis than was 1α,25(OH)2D3, and the natural metabolites 25-hydroxyvitamin D3 (25OHD3) and 24R,25-dihydroxyvitamin D3 (24R,25(OH)2D3), 1000-fold less potent, although the dose-response curve for each of these compounds was not parallel with that for 1α,25(OH)2D3. The 24S,25(OH)2D3 enantiomer was four-fold less potent than 24R,25-(OH)2D3 or 25OHD3, and vitamin D3 showed less than 2% the activity of 25OHD3. The responses were unaffected by the substitution of 0.4% bovine albumin for 5% horse serum in the medium, and no stimulation of collagen synthesis was observed in response to 25-hydroxylated metabolites between 2×10−14 and 2×10−6 M or in cultures treated for up to 96 h with 24R,25(OH)2D3 (2×10−10M). The overall results emphasize the similarity of the structural requirements for the inhibition of matrix synthesis and the stimulation of resorption by active vitamin D metabolites in bone. In addition, these studies support the importance of the 1-hydroxyl function to the biologic activity of vitamin D in the skeleton.
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    Inhibition of apatite crystal growth by the amino-terminal segment of human salivary acidic proline-rich proteins (1984)
    Springer
    Calcified tissue international 36 (1984), S. 651-658 
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    ISSN: 1432-0827
    Keywords: Salivary proteins ; Hydroxyapatite ; Adsorption ; Precipitation-inhibitor ; Phosphoserine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Inhibition of seeded apatitic crystal growth by human salivary acidic proline-rich phosphoproteins (PRP) has been related to their adsorption onto the apatite seeds. The amino-terminal 30-residue segment of the PRP makes an important contribution to this adsorption. This peptide (PRP1(T1)) and its dephosphorylated analogue from PRP3 (PRP3(T1)DP) were prepared. They have identical sequences, except the phosphates at residues 8 and 22 in PRP1(T1) are absent from PRP3(T1)DP. Adsorption of these peptides onto hydroxyapatite and their effect on crystal growth from a defined supersaturated solution was studied. Adsorption behavior was adequately described by the Langmuir adsorption isotherm. The adsorption affinity constant of PRP1(T1) (K=20,200 ml/µmol) was more than 10 times the corresponding value for PRP3(T1)DP (1,800 ml/µmol), and similar to that of the parent protein, PRP1 (26,200 ml/µmol). Inhibition of crystal growth by the peptides was interpreted in terms of the fractional coverage of the maximum number of adsorption sites (as derived from the adsorption isotherms), suggesting that the molecules block, by adsorption, specific growth sites on these surfaces. Comparison of precipitation kinetics showed that PRP1(T1) is a more effective inhibitor than PRP3(T1)DP at the same initial concentration (10−6−10−7 M). However, on the basis of per mol adsorbed, PRP3(T1)DP displays a greater inhibitory activity; such a behavior is consistent with a more open molecular structure which blocks more growth sites per mol adsorbed than PRP1(T1). Because of its high affinity constant, preadsorbed PRP1(T1) remains in the condensed state in the supersaturated solution used, whereas the preadsorbed PRP3(T1)DP molecules desorb to some extent, resulting in a decrease in inhibitory activity. The results show that the amino-terminal segment of the PRP and the two phosphoserine residues present in this segment are particularly important in the function proposed for these proteins in the oral environment.
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    Changes in plasma bone GLA protein during treatment of bone disease (1982)
    Springer
    Calcified tissue international 34 (1982), S. 121-124 
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    ISSN: 1432-0827
    Keywords: Bone ; Calcium ; Metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Bone Gla protein (BGP) was measured in the plasma by radioimmunoassay (RIA) during treatment of 59 patients with bone diseases including Paget's disease (N=9), primary hyperparathyroidism (N=25), chronic renal failure (N=20), and cancer involving bone (N=5). Plasma BGP was increased above normal in all patients. BGP decreased in the patients with Paget's disease following the acute and chronic administration of salmon calcitonin. Plasma BGP was higher in women then in men with primary hyperparathyroidism. Following parathyroidectomy, BGP decreased in both sexes but the decrease was significant in women only. Plasma BGP was increased in patients with renal osteodystrophy and did not change after hemodialysis. In the patients with bone cancer, plasma BGP decreased during treatment of the attendant hypercalcemia with salmon calcitonin. Although plasma BGP and serum alkaline phosphatase (AP) levels were generally correlated in these studies, there were examples of dissociation between the two. The measurement of plasma BGP appears to provide a specific index of bone metabolism that may in some circumstances be more sensitive than serum alkaline phosphatase measurement. However, further studies are necessary to establish the clinical value of plasma BGP measurement by RIA in the management of patients with bone diseases.
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    Tensile properties of antler bone (1982)
    Springer
    Calcified tissue international 34 (1982), S. 301-305 
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    ISSN: 1432-0827
    Keywords: Antler ; Bone ; Collagen ; Tension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The tensile deformation characteristics of compact bone from deer antler were measured in both the “dry” and “wet” states and compared with published values for bovine compact bone. The tensile strength in the wet state (108±5.1 MN/m2) was comparable to the value for bovine compact bone tested at the same strain rate. The modulus value was very low: 7.5±0.9 GN/m2. The work to fracture was comparatively high, about 3 times that for bovine compact bone. Fractographic examination revealed fibrillar and osteonal shear for samples fractured in the dry state. In the samples tested in the wet state, some regions exhibited pull-out of lamellar segments from within a Haversian system. The results are explained in terms of the higher collagen content and lesser degree of mineralization in the antler.
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    Activation of serum complement inhibits collagen synthesis in fetal rat bone in organ culture (1982)
    Springer
    Calcified tissue international 34 (1982), S. 370-375 
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    ISSN: 1432-0827
    Keywords: Complement ; Bone ; Collagen ; Prostaglandins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Activation of rabbit serum complement caused a marked reduction in collagen synthesis but a much smaller change in noncollagen protein synthesis in fetal rat calvaria maintained in organ culture. In the periosteum of the fetal rat calvarium, both collagen and noncollagen protein synthesis were reduced, whereas in the central bone, presumably enriched in osteoblasts, only collagen synthesis was inhibited. This large decrease in bone collagen synthesis could not be attributed to enhanced degradation of newly synthesized collagen or its release into the culture medium. Activation of complement also stimulated the production of PGE in fetal rat calvaria. Antagonists of prostaglandin cyclooxygenase decreased prostaglandin synthesis but did not restore collagen synthesis in complement-treated bones, suggesting that complement decreases osteoblast collagen synthesis by a mechanism largely independent of prostaglandin production.
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    Adsorption of molecules of biological interest onto hydroxyapatite (1984)
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    Calcified tissue international 36 (1984), S. 48-59 
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    ISSN: 1432-0827
    Keywords: Salivary proteins ; Adsorption ; Thermodynamics ; Kinetics ; Hydroxyapatite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Equilibrium and kinetic experiments were conducted to investigate the factors determining the adsorption of salivary macromolecules onto hydroxyapatite. Using amino acids and other small adsorbates, it was determined that the carboxyl attached to the α carbon does not appear to adsorb onto HA and the affinities of side-chain carboxyls are much smaller than that of the phosphate group (phosphoserine). Hydroxyl (serine) displays an extremely high affinity, but its adsorption site on HA is different and the number of such sites is much smaller than found for the rest of the functional groups investigated. It is shown that the information obtained from small molecules cannot be readily applied to prediction of the adsorption behavior of salivary macromolecules and polypeptides. The kinetics of adsorption of the salivary phosphopeptide statherin, a polyaspartate, and the salivary prolinerich phosphoprotein PRP3 are consistent with the reversibility of the adsorption process; no conclusion was possible in the case of the protein PRP1. Apparent irreversibility cannot be explained on the basis of multipoint binding or the properties of the carboxyl versus phosphate group; it appears that secondary structure determines to a significant extent the adsorption properties of the macromolecules. Calculation of the thermodynamic molar quantities of adsorption of PRP1, PRP3, andl-ASP onto HA showed that the process is entropically driven. The functional relationship between partial molar entropy and adsorption coverage is similar for the two proteins, but quite different from that for aspartate. Explanations for these results are advanced on the bases of changes in structure configurations and displacement of water from the adsorbate and the adsorbent surface, the second factor being the dominant one in the adsorption of a small molecule such asl-ASP.
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    Alkyl-phenyl cleavage of the lignin model compounds guaiacylglycol and glycerol-β-guaiacyl ether by Phanerochaete chrysosporium (1980)
    Springer
    Archives of microbiology 128 (1980), S. 190-195 
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    ISSN: 1432-072X
    Keywords: Phanerochaete chrysosporium ; Lignin model compounds ; β-Aryl ether dimers ; Metabolism ; Methoxyhydroquinone ; Alkyl-phenyl cleavage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The white rot basidiomycete Phanerochaete chrysosporium metabolized guaiacylglycol-β-guaiacyl ether (I) in high nitrogen, shaking and stationary cultures. 2-(o-Methoxyphenoxy) ethanol (X), 2-(o-methoxyphenoxy) acetic acid (IX) and methoxy-phydroquinone (MHQ) were identified as products of the metabolism of (I). P. chrysosporium also metabolized guaiacylglycerol-β-guaiacyl ether (IV) in high nitrogen stationary cultures. 2-(o-Methoxyphenoxy)-1,3 propanediol (XII) and 3-hydroxy, 2-(o-methoxy-phenyxy) propionic acid (XIV) were identified as products of the metabolism of (IV). Finally, P. chrysosporium metabolized α-deoxyguaiacylglycol-β-guaiacyl ether (VI) and α-deoxyguaiacylglycerol-β-guaiacyl ether (VII) in limiting nitrogen cultures. 2-(o-Methoxyphenoxy) ethanol (X) and 2-(o-methoxyphenoxy)-1,3 propanediol (XII) were identified as products of the metabolism of VI and VII respectively indicating α hydroxylation of those substrates with subsequent alkyl-phenyl bond cleavage. Metabolites were identified after comparison with chemically synthesized standards by GLC-mass spectrometry.
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    Selenite uptake and incorporation by Selenomonas ruminatium (1984)
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    Archives of microbiology 140 (1984), S. 252-256 
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    ISSN: 1432-072X
    Keywords: Selenomonas ruminantium ; Selenite uptake ; Metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Selenite uptake and incorporation in Selenomonas ruminantium was constitutive with an inducible component. It was distinct from sulphate or selenate transport, since sulphate and selenate did not inhbit uptake, nor could sulphate or selenate uptake be demonstrated. Selenite uptake had an apparent K m of 1.28 mM and a V max of 148 ng Se min-1 mg-1 protein. Uptake was sensitive to inhibition by 2,4-dinitrophenol (DNP), carbonyl cyanide m-chlorophenyl hydrazone (CCCP), azide, iodoacetic acid (IAA) and N-ethylmaleimide (NEM), but not chloropromazine (CPZ), N,N′-dicyclohexyl-carbodiimide (DCCD), quinine, arsenate, or fluoride. Treatment of cells accumulating 75[Se]-Selenite with 2,4,DNP inhibited uptake, but did not cause efflux. Transport of selenite was inhibited by sulphite and nitrite, but not by nitrate, phosphate, sulphate of selenate. 75[Se]-Selenite was incorporated into selenocystine, selenoethionine, selenohomocysteine, and selenomethionine and was also reduced to red elemental selenium.
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    Botryococcus braunii carbon/nitrogen metabolism as affected by ammonia addition (1984)
    Springer
    Archives of microbiology 140 (1984), S. 101-106 
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    ISSN: 1432-072X
    Keywords: 5-aminolevulinic acid ; Ammonia ; botryococcus braunii ; Botryococcenes ; Carbon ; Hydrocarbon ; Metabolism ; Nitrogen ; Resting state ; Terpenoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Carbon metabolism in photosynthesizing and respiring cells of Botryococcus braunii was radically changed by the presence of 1 mM NH4Cl in the medium, when the so-called “resting state” previously had been subjected to a nitrogen-deficient medium. Ammonia addition to the algae photosynthesizing with 14C-labelled HCO 3 - almost completely inhibited the synthesis of 14C-labelled botryococcenes and other hexane-extractable compounds, and also inhibited the formation of insoluble compounds; however, it resulted in a large increase in the synthesis of alanine, glutamine, other amino acids, and especially of 5-aminolevulinic acid. Total CO2 fixation decreased about 60% and O2 evolution decreased more than 50%. CO2 fixation in the dark with ammonia present led to labelled products derived from phosphoenolpyruvate carboxylation, such as glutamine, glutamate, and malate. Respiratory uptake of O2 increased by about 70%. The inhibition of terpenoid synthesis and increased synthesis of C5 amino acids by Botryococcus upon ammonia addition indicates 1) a diversion of acetyl coenzyme A from synthetic pathways leading to terpenoids and 2) increased operation of pathways leading to the synthesis of amino acids, especially 5-aminolevulinic acid, a precursor to chlorophyll biosynthesis.
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    Hypertrophic smooth muscle (1984)
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    Cell & tissue research 235 (1984), S. 275-283 
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    ISSN: 1432-0878
    Keywords: Smooth muscle ; Intestine ; Hypertrophy ; Collagen ; Capillaries ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In adult guinea-pigs, oral to a partial obstruction to the flow of ingesta in the ileum there is a marked increase in the diameter of the intestine and a hypertrophy of the muscle coat. The features of the intramuscular blood vessels and of the extracellular materials were studied by electron microscopy. There is a small increase in the amount of intercellular space measured morphometrically. The basal lamina surrounding the hypertrophic muscle cells is more prominent than in controls. In the intercellular space between muscle cells, in addition to collagen fibrils, there is abundant amorphous material of medium electron density and streak-like, electron-dense material often similar to thickened basal laminae. The total amount of stroma (intercellular materials) present in a unit length of intestine is greatly increased in hypertrophy; a role of the muscle cells in the production of new collagen and other extracellular elements is suggested by the present observations. Many new intramuscular blood vessels (mainly capillaries, some of which are fenestrated) are formed during hypertrophy of the intestinal wall, so that the circular muscle layer remains as well vascularized in the hypertrophic intestine as in the controls. Blood vessels are not formed within the longitudinal muscle layer.
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    Changes in metabolism and hepatic ultrastructure induced by estradiol and testosterone in immature female Epinephelus akaara (Teleostei, Serranidae) (1984)
    Springer
    Cell & tissue research 236 (1984), S. 651-659 
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    ISSN: 1432-0878
    Keywords: Steroids ; Vitellogenesis ; Metabolism ; Ultrastructure ; Teleosts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Estradiol injections increase serum level of calcium, amino acid, glucose, protein, ammonia and creatinine in immature Epinephelus akaara, and also increase levels of total lipid, cholesterol, phospholipid and esterified fatty acids. Hepatic protein, glycogen and lipid concentrations also rise after estradiol treatment, and some hepatic enzymes participating in the metabolism of nitrogen, lipid and carbohydrate, show increased activity. Serum vitellogenin levels are increased. Testosterone treatment increases serum protein, total lipid, cholesterol, amino acid and ammonia levels, and also hepatic glycogen content, but in contrast to estradiol treatment, testosterone does not change serum vitellogenin, glucose, calcium, phospholipid, esterified fatty acid and creatinine levels, nor the hepatic lipid and protein content. A small number of hepatic enzymes shows an increased activity. Vitellogenic fish show biochemical changes similar to that of estradiol-treated fish, but are different from those of immature fish. Estradiol treatment induces ultrastructural changes in the hepatocytes of immature fish that are similar to those found in vitellogenic fish. These include a proliferation of rough endoplasmic reticulum and Golgi apparatus, and an increase in glycogen and lipid, all indicative of enhanced metabolic activity.
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    Spatial relationships between fibroblasts during the growth of rat-tail tendon (1983)
    Springer
    Cell & tissue research 234 (1983), S. 17-29 
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    ISSN: 1432-0878
    Keywords: Tendon (rat) ; Development ; Fibroblasts ; Collagen ; Extracellular space
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Sections of tendons from the base of the tail of rats were taken at eight time intervals from 18 days in utero until 244 days after birth and were examined in the electron microscope. For each time period, measurements were made of the relative area of fibroblasts, collagen and interstitial material, of the number of fibroblasts per unit area of tendon and of the average area of individual fibroblasts. The spatial arrangement of fibroblasts in the tendon sections was described quantitatively using the “nearest neighbor” method. Initially there was a rapid increase in the area of collagen accompanied by a decrease in the area occupied by fibroblasts but after 104 days of age these values changed very little. The numbers of fibroblasts per unit area decreased steadily from the embryo until 104 days whereas the average size of each cell increased to reach a maximum area at 40 days of age and then declined. At all time intervals cells were arranged in a regular, dispersed pattern across the tendon fascicles. Growth in width of the rat tail appears to involve the secretion of collagen and other intercellular material symmetrically around each fibroblast, so as to gradually separate the cells until a stage is reached at which cells are sufficiently far apart that there is little contact between adjacent cell processes. This may interfere with the integration of metabolic activity in the tissue. As a consequence, there is shrinkage of the cell bodies and a reduction in secretory activity so that, between 55 and 104 days of age, the tendon enters a period of terminal senescence.
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    Correlation of specific sulfated glycosaminoglycans with collagen types I, II, and III (1981)
    Springer
    Cell & tissue research 217 (1981), S. 171-175 
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    ISSN: 1432-0878
    Keywords: Glycosaminoglycans ; Collagen ; Correlative analysis ; Biochemical assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A qualitative and quantitative biochemical study of the glycosaminoglycans was performed in tissues constituted predominantly by one type of collagen, or in tissues containing mixtures of different types of collagen. The results obtained show the presence of dermatan sulfate, chondroitin sulfate, and heparitin sulfate in tissues containing collagen types I, II, or III, respectively, suggesting a specific correlation of different glycosaminoglycans with these three types of collagen.
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    Assessment of overall metabolism inAmoeba proteus measured by a microcalorimetric method (1984)
    Springer
    Protoplasma 123 (1984), S. 135-139 
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    ISSN: 1615-6102
    Keywords: Amoeba proteus ; Metabolism ; Microcalorimeter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have carried out calorimetric determinations of the overall metabolism ofAmoeba proteus. There was no significant difference in metabolic activity between cells that were starved 3, 4, and 5 days. After 7 and 10 days a significantly lower metabolism was found (p 〈 0.05). The mean value of heat production rate (thermal power) for the cells after 3 days starvation was found to be 0.84 ± 0.14 nW/cell. Optimal number of cells in the ampoule (1,500–4,800) was accompanied by a steady-state power-time curve. With higher cell concentrations (〉 5,000) the power-time curve showed an initial peak. The fall in heat production after about 1 hour varied between 30–60%. The decrease in power value was much larger than expected from cell mortality during the calorimetric experiment. Increasing number of cells (range 1,500–10,000) in the calorimetric ampoule caused a decrease of heat production rate per cell. The correlation coefficient was r=−0.85(p 〈 0.001). The coefficient of variation of the method was found to be 4.8 %. It seems that the use of microcalorimetric technique can be valuable in recording metabolic events in protozoes.
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    Turnover with nonidentical sources of labelled and unlabelled substance (1982)
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    Annals of biomedical engineering 10 (1982), S. 161-174 
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    ISSN: 1573-9686
    Keywords: Tracer kinetics ; Compartments ; Turnover ; Metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The rate of appearance or production of a metabolite in steady state in an intact animal (e.g., the number of moles per minute of glucose or lactate which are released into the blood) is measured by infusing a tracer into the system at a constant rate. Often one can regard both the unlabelled metabolite and the labelled metabolite (tracer) as entering the system in the same fluid pool, so that as equilbrium is approached, specific activity (the ratio of the concentration of labelled to unlabelled substance) becomes constant throughout the organism. The method for calculating the rate of appearance for this case is well known. When it is not possible to infuse the tracer in such a manner, gradients in specific activity must appear. This necessitates a change in the method of calculation. The rate at which the unlabelled metabolite enters the body is now given by the rate of infusion of tracer, multiplied by the ratio of the concentration of the unlabelled substance in the pool of entry of the tracer, to the concentration of the tracer in the pool of entry of the unlabelled metabolite. Violation of this rule can produce appreciable errors in the calculation of the rate of appearance. This new rule suggests a generalization of the concept of specific activity.
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    Plant injury and adaptation to oxygen deficiency in the root environment: A review (1983)
    Springer
    Plant and soil 75 (1983), S. 179-199 
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    ISSN: 1573-5036
    Keywords: Anaerobic ; Diffusion ; Flooding ; Injury ; Metabolism ; Oxygen ; Roots ; Structure ; Temperature ; Waterlogging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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    Metabolic uniformity over the environmental temperature range in Brachionus plicatilis (rotifera) (1980)
    Springer
    Hydrobiologia 73 (1980), S. 145-147 
    Details
    ISSN: 1573-5117
    Keywords: Rotifers ; Metabolism ; Metabolic Rate ; Respiration ; Zooplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Organisms inhabiting small water bodies frequently encounter radical, short-term fluctuations in temperature. The population of Brachionus plicatilis that was used in this study encounters temperature changes as great as 12°C in 24 hours. In this paper we describe the metabolic response to temperature change in this eurythermal rotifer population. Metabolism was determined over the environmental range (15°C to 32°C) in intervals of 2°C. Utilization of such narrow temperature intervals allowed us to approximate the instantaneous Q10, which we define as the Q10 over an infinitely small temperature interval. Our results show the existence of a plateau in the curve of respiration against temperature (Q10 〉 1) over the range 20–28°C. The plateau is bounded on either side by temperature ranges over which metabolism is temperature sensitive (Q10 values from 3.4 to 4.8). It is significant that the plateau occurs over the environmental temperature range for the major portion of the growing season. This population is thus programmed to hold a constant (preferred?) metabolic rate in spite of diel temperature fluctuations when the environment is otherwise favorable.
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    URL: http://dx.doi.org/10.1007/BF00019439
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    Toxic responses of germinating pollen and soybeans to aflatoxins (1980)
    Springer
    Mycopathologia 72 (1980), S. 67-73 
    Details
    ISSN: 1573-0832
    Keywords: Aflatoxin ; Germination ; Elongation ; Metabolism ; Pollen ; Soybeans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Aflatoxin producing strains of Aspergillus grow on soybeans thereby contaminating the latter through secretion of the toxin. Investigations dealing with either soybean seed germination or intact seedling growth responses to aflatoxin (B1) are lacking. Similarly, a possible interaction of aflatoxins with phosphate in the germination and elongation of both soybeans and pollen as well as roots of the former and tubes of the latter has not been examined. Imbibition of Glycine max, cv. ‘Essex’ seeds for 18 hours in solutions containing 0.38, 2.90, 5.80 or 11.60 μg/ml (AFB1) yielded% germination inhibitions of 5, 20, 40 and 80, respectively. By 36 hours these were 6, 4, 13 and 19 % for the same toxin concentration series. At 140 hours attached root elongation was inhibited 26, 35 and 50 % for 2.90, 5.80 and 11.60 μg/ml AFB1. No effect was noted at 0.38 μg/ml AFB1. Incubation of excised roots in medium containing 3.0 mM KH2PO4 stimulated their elongation 3.2 fold. Addition of 33.28 μg/ml mixed aflatoxins together with KH2PO4 resulted in only a 1.5 fold stimulation. When KH2PO4 was added to a culture medium lacking AFB1, Lilium longiflorum, cv. ‘Ace’ pollen germination was enhanced 50%. Withholding KH2PO2 but supplying AFB1 did not markedly affect germination. However, supplementing the medium with KH2PO4 while simultaneously adding AFB1 did not inhibit germination at 5 and 10 μg/ml but caused 27.3 and 45.1 % declines at 25 and 30 μg/ml. In the absence of KH2PO4 AFB1 stimulated pollen tube elongation 7.5, 14.3, 16.5 and 13.2 % at 5, 10, 15 and 20 μg/ml but 30 μg/ml inhibited it 11.1%. In contrast, tube elongation was suppressed at all AFB1 concentrations (maximum 36.1% at 30 μg/ml) tested upon KH2PO4 addition. Results derived from germinating pollen in medium supplemented with KH2PO4 or NaH2PO4 indicate that the phosphate anion does not preferentially promote aflatoxin-induced inhibition of tube elongation.
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    URL: http://dx.doi.org/10.1007/BF00493813
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    Effects of boron on nitrogen metabolism and sugar levels of sugar beet (1980)
    Springer
    Plant and soil 57 (1980), S. 3-9 
    Details
    ISSN: 1573-5036
    Keywords: B-deficient ; B-toxic ; Corrections ; Growth ; Leaf ; Metabolism ; Molybdenum ; Nitrate ; NRase ; Potassium ; Root ; Sap ; Sugar ; Yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effects of deficient and toxic levels of boron on various aspects of nitrogen metabolism in sugar beet are studied. Plant analysis shows a nitrate ion accumulation, a decrease in the activity of the nitrate reductase enzyme and a lower molybdenum absorption. The effect of boron levels on the plant and root sugar concentration has also been studied.
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    URL: http://dx.doi.org/10.1007/BF02139636
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    Ultrastructure and metabolism of skeletal muscle fibres in the tench: Effects of long-term acclimation to hypoxia (1982)
    Springer
    Cell & tissue research 227 (1982), S. 179-199 
    Details
    ISSN: 1432-0878
    Keywords: Hypoxia acclimation ; Muscle ultrastructure ; Liver ; Metabolism ; Teleosts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Tench (Tinca tinca) were acclimated to either aerated (P O 2 17.6 KPa) or hypoxic (P O 2 1.5 KPa) water for 6 weeks. Acclimation to hypoxia resulted in a decrease in mitochondrial volume fraction in both slow (22.9 to 15.0 %) and fast glycolytic (4.5 to 1.8 %) myotomal muscles fibres (P〈0.01). Intermyofibrillar mitochondrial populations (4.4 to 1.2% slow; 0.6 to 0.04% fast fibres) were affected to a greater extent than those in the subsarcolemmal zone (18.5 to 13.8% slow; 3.9 to 1.8% fast fibres). After acclimation to hypoxia, cytochrome-oxidase activities decreased by 31 and 33 % in slow and fast fibres, respectively, but were maintained in the liver. Fibre size remained unchanged and actively differentiating fibres were observed in muscles from both groups of fish. Hypoxia resulted in a significant increase in myofibrillar volume fraction in both slow (43.1 to 56.1 %) and fast glycolytic fibres (73.1 to 82.7%) (P〈0.05). Glycogen concentrations (mg/100g tissue) for liver (6616) slow muscle (1892) and fast muscle (334) were similar for fish acclimated to aerated or hypoxic water. Acclimation to hypoxia increased carnitine palmitoyl transferase activity (μmoles substrate utilised g·dry wt-1 min-1) in slow (0.42 to 1.1), fast glycolytic muscle (〈0.01 to 0.15) and liver (1.1 to 3.7) indicating an enhanced capacity for fatty acid oxidation. Phosphofructokinase activities of fast glycolytic fibres were similar in fish acclimated to either aerated or hypoxic water, consistent with an unaltered capacity for anaerobic glycogenolysis. Hexokinase activities (μmoles substate utilised, g·dry wt-1 min-1) decreased in fast fibres (1.2 to 0.4) but were maintained in the slow muslce (2.1 to 2.5) and liver (4.5 to 4.8) of hypoxic fish. The activities of phosphofructokinase in slow muscle and phosphofructokinase, pyruvate kinase and lactate dehydrogenase in liver were two times higher in fish acclimated to hypoxia. An enhanced capacity for glycolysis in these tissues may reflect a reduced threshold for anaerobic metabolism during activity and/or an adaptation for acute exposure to anoxia in fish acclimated to hypoxia.
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    URL: http://dx.doi.org/10.1007/BF00206340
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    Adhesion to extracellular materials by neural crest cells at the stage of initial migration (1982)
    Springer
    Cell & tissue research 227 (1982), S. 297-317 
    Details
    ISSN: 1432-0878
    Keywords: Neural crest ; Fibronectin ; Collagen ; Proteoglycans ; Cell adhesion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Trunk-level neural anlagen bearing neural crest cells at the stage of initiation of migration were isolated from chick embryos and explanted in serum-free medium onto glass substrates which had previously been treated with extracellular materials. After 0.5–2 h incubation, the expiants were dislodged with a stream of culture medium and the substrate examined for adherent crest cells. Crest cells adhered to collagen gels, and adhered to and spread on adsorbed fibronectin; antiserum to fibronectin prevented adhesion to fibronectin but not to collagen gels. Air-dried collagen gels and collagen solutions were less adhesive, the adhesivity declining with longer drying time and lower collagen concentration. Crest cells adhered poorly to dried gelatin and not at all to adsorbed collagen. Fibronectin increased the adhesion to dried collagen and gelatin. Pretreatment of collagen gels with hyaluronate retarded adhesion. Hyaluronate pretreatment also retarded adhesion to adsorbed fibronectin but only when adsorbed collagen was also present. Pretreatment of collagen gels with the proteoglycan monomer from bovine nasal cartilage had no effect of the adhesion of crest cells, but the proteoglycan almost completely inhibited adhesion to adsorbed fibronectin, but only when absorbed collagen was also present. The results are discussed in terms of the control of migration of neural crest cells by extracellular materials.
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    URL: http://dx.doi.org/10.1007/BF00210888
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    Tissue uptake of circulating hyaluronic acid (1983)
    Springer
    Cell & tissue research 233 (1983), S. 285-293 
    Details
    ISSN: 1432-0878
    Keywords: Hyaluronic acid ; Circulation ; Tissue uptake ; Autoradiography ; Metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Previous work in the rabbit has shown that there is a significant flux of plasma hyaluronic acid (HA)1 which is taken up and degraded mainly in the liver but also concentrated in the spleen. Purified 14C-labelled HA of high average molecular wt prepared by biosynthesis from D-[U-14C] glucose was injected i.v. in mice and its tissue distribution was determined by whole-body autoradiography during the next 24 h. As blood levels declined, radioactivity was concentrated in the liver and spleen as found in the rabbit, and also in bone marrow and lymph nodes. Distribution was uniform in liver tissue, concentrated and relatively persistent in the periphery of lymph nodes, and distinctly nodular within the spleen. Analysis of an aqueous liver extract taken 4 h after injection identified 14C in HA, in a macromolecular fraction resistant to fungal hyaluronidase, and in metabolites of low molecular wt. These findings confirm and extend observations based on tissue extraction in rabbits. The pattern of distribution through the body and the restricted localization within spleen and lymph nodes further suggest that HA is absorbed from plasma and tissue fluids by elements of the reticuloendothelial system.
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    URL: http://dx.doi.org/10.1007/BF00238296
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    Effect of ultraviolet light on the dielectric behavior of bone at microwave frequencies (1982)
    Springer
    Annals of biomedical engineering 10 (1982), S. 139-144 
    Details
    ISSN: 1573-9686
    Keywords: Dielectric constant ; Bone ; Collagen ; Apatite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The dielectric constant of bone and its two components (collagen and apatite) were determined at 9.2 GHz in a room temperature environment by the cavity perturbation technique. After samples were exposed to ultraviolet light, repeat measurements under identical conditions showed decreases in both the real and the imaginary parts of the dielectric constant in all cases. The present work describes the technique and a possible mechanism of ultraviolet interaction with bone.
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    Association of Thy-1 cell surface differentiation antigen with certain connective tissues in vivo (1980)
    Springer
    Cell & tissue research 206 (1980), S. 459-475 
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    ISSN: 1432-0878
    Keywords: Antigens ; Cell surface ; Connective tissue ; Collagen ; Cell membrane proteins ; Morphogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cell surface differentiation antigen, Thy-1, has been demonstrated by immunofluorescence to be associated with some collagen-based connective tissue. In the rat, the basement membrane of kidney collecting tubules and of certain blood vessels, reticulin of the lamina propria, loose connective tissue in the dermis, and collagen fibres within certain nerve cell tumours, bear the antigen. Other, apparently similar, connective tissue (especially that of muscle and liver) lacked Thy-1. In the mouse, only the connective tissue of the skin was found to bear the antigen. The possible origin of this extracellular Thy-1, and its implications for the function of the molecule, are discussed.
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    An ultrastructural and cytochemical analysis of the cellular basis for tyrosine-derived collagen crosslinks in Leptogorgia virgulata (Cnidaria: Gorgonacea) (1982)
    Springer
    Cell & tissue research 222 (1982), S. 635-645 
    Details
    ISSN: 1432-0878
    Keywords: Cnidaria ; Skeleton ; Connective tissue ; Collagen ; DOPA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron-microscopical autoradiography and cytochemical techniques have been used to identify the distinct and separate subcellular structures involved in the secretion of 1) procollagen, 2) dihydroxyphenylalanine (DOPA), which is a precursor of a collagen-crosslinking compound, and 3) DOPA oxidase, which converts DOPA to a putative crosslinking compound of collagen in the axial skeleton of the gorgonian coral Leptogorgia virgulata. Some skeletal-protein hydrolysates contain material that co-elutes with DOPA. The data indicate that these skeletogenic cells, corticocytes, are capable of modifying the number of non-reducible, tyrosine-derived crosslinkages of collagen by the secretion of a crosslinking compound that acts extracellularly on collagen. A mechanism for a cell-mediated control of the mechanical properties of collagen is thereby presented.
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    Routine overnight starvation and immunocytochemistry of hepatocyte albumin content (1982)
    Springer
    Cell & tissue research 227 (1982), S. 423-427 
    Details
    ISSN: 1432-0878
    Keywords: Liver (Rat) ; Albumin ; Metabolism ; Hepatocytes ; Immunocytochemistry ; Nutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The indirect immunoperoxidase method was used to identify albumin in hepatocytes of rats before and after periods of starvation. All hepatocytes in fed rats contained a relatively large amount of nascent albumin. Overnight fasting reduced the number of hepatocytes with a large amount of albumin to primarily those surrounding terminal hepatic venules. These were estimated to be about 30% of the population. The other cells had only a slight amount of albumin. After 48 h of fasting all hepatocytes contained a low level of albumin.
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    Structural evidence for insertion of collagen fibres to smooth muscle cells in the carotid arterial system of the giraffe (Giraffa camelopardalis) (1981)
    Springer
    Cell & tissue research 214 (1981), S. 219-224 
    Details
    ISSN: 1432-0878
    Keywords: Smooth muscle ; Collagen ; Carotid arteries ; Giraffe ; Cell cohesion ; Nexus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Previous anatomical studies have failed to resolve the question relating to whether or not collagen fibres, like elastic fibres, are attached to smooth muscle cells in the arterial wall. The current ultrastructural study demonstrates the insertion of collagen fibres to the sarcolemmal dark areas in the smooth muscle cells of the carotid arterial system of the giraffe. It is concluded, therefore, that this morphological linkage between collagen and smooth muscle cells may facilitate transmission of the force of contraction between the cells and to the surrounding connective tissue framework since the myofilaments appear to be spatially placed in series with the extracellular collagen fibres at the sarcolemmal dark areas.
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    URL: http://dx.doi.org/10.1007/BF00235159
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    A comparative scanning electron-microscopical study of endoneurial collagen around normal mouse nerve fibres, nerve fibres following crush injury and nerve fibres of the dystonic mouse mutant (dt/dt) (1981)
    Springer
    Cell & tissue research 220 (1981), S. 881-887 
    Details
    ISSN: 1432-0878
    Keywords: Sciatic nerve ; Endoneurial sheath ; Collagen ; Injuries ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The endoneurial collagen sheath around teased nerve fibres following crush injury was studied by scanning electron microscopy and compared with uninjured sciatic nerve fibres and with fibres from the dystonic mutant mouse. Following crush injury the endoneurial collagen became more abundant than seen in untreated nerve fibres and formed large, separate and longitudinally oriented bundles. However, by four weeks post injury the sheath regained a normal external appearance. Mutant nerve fibres were also associated with more than the usual amount of collagen, but the sheaths were more disorganised, with a marked disorientation and irregular aggregation of collagen, and these abnormalities were not confined to obviously degenerating or demyelinated regions of the fibres. The dystonic abnormalities of the endoneurial sheath may be important in the mechanism of the neuropathy.
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    Ultrastructural and tissue-culture studies on the role of fibronectin, collagen and glycosaminoglycans in the migration of neural crest cells in the fowl embryo (1982)
    Springer
    Cell & tissue research 221 (1982), S. 521-549 
    Details
    ISSN: 1432-0878
    Keywords: Fibronectin ; Collagen ; Glycosaminoglycans ; Cell migration ; Neural crest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The initial migration of neural crest (NC) cells into cell-free space was studied by transmission electron microscopy at trunk levels of fowl embryos, some of which were fixed in the presence of ruthenium red. Migrating NC cells occurred in zones which contained fewer ruthenium-red stained 15–40 nm diameter granules than other regions. The ruthenium-red stained granules were linked by similarly stained thin (⪖ 3 nm diameter) microfibrils. The granules resemble proteoglycan and the microfibrils may be hyaluronate. NC cells contacted thicker (⪖ 10 nm diameter) fibrils and interstitial bodies, which did not require ruthenium red for visualization. Cytoplasmic microfilaments were sometimes aligned at the point of contact with the extracellular fibrils, which may be fibronectin and collagen. Phase-contrast time-lapse videotaping and scanning electron microscopy showed that NC cells of the fowl embryo in vitro migrated earlier and more extensively on glass coated with fibronectin-rich fibrous material and adsorbed fibronectin molecules than on glass coated with collagen type I (fibres and adsorbed molecules). NC cells became completely enmeshed in fibronectin-rich fibres, but generally remained on the surface of collagen-fibre gels. When given a choice, NC cells strongly preferred fibronectin coatings to plain glass, and plain glass to dried collagen gels. NC cells showed a slight preference for plain glass over glass to which collagen was adsorbed. Addition to the culture medium of hyaluronate (initial conc. 20 mg/ml), chondroitin (5 mg/ml) and fully sulphated chondroitin sulphate and dermatan sulphate (up to 10 mg/ml) did not drastically alter NC cell migration on fibronectin-rich fibrous substrates. However, partially desulphated chondroitin sulphate (5mg/ml) strongly retarded the migration of NC cells. The in vivo and in vitro studies suggest that fibronectin may dictate the pathways of NC cell migration by acting as a highly preferred physical substrate. However, the utilization of these pathways may be reduced by the presence of proteoglycans bearing undersulphated chondroitin sulphate.
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    Autoradiographic studies of protein and polysaccharide synthesis during vitellogenesis in Drosophila (1982)
    Springer
    Cell & tissue research 224 (1982), S. 315-333 
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    ISSN: 1432-0878
    Keywords: Oogenesis ; Vitellogenesis ; Radiolabelling ; Metabolism ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Quantitative light- and electron-microscopic autoradiography was used to evaluate metabolic processes that occur during late developmental stages (10–14) of oogenesis in Drosophila melanogaster. Major differences in radiolabelling patterns were found after in vivo (10–45 min) uptake of [3H]-monosaccharides and [3H]-L-lysine. Several different methods of data analysis were required to facilitate interpretation of these patterns. [3H]-L-lysine produced extensive cytoplasmic labelling at all developmental stages. In addition, about 15% of alpha yolk spheres were intensely labelled at stage 10, reflecting the incorporation of radiolabelled vitellogenins synthesized during the incubation period. Subsequent stages showed low silver grain density over alpha yolk spheres until stage 14, when a burst of [3H]-L-lysine incorporation by most alpha spheres was observed, possibly indicative of a maturation process for embryogenesis. [3H]-D-glucose and [3H]-D-galactose (10 min, in vivo) both induced intense labelling of the beta yolk spheres in a manner suggesting in situ assembly beginning at early stage 13. Inasmuch as the polysaccharide of beta yolk spheres has the properties of glycogen (e.g., rosette structure digested by α-amylase) and the radiolabelled monosaccharides were introduced intraabdominally, it is evident that transport systems as well as enzymes utilizing glucose and galactose for glycogenesis must be readily available. It is notable that wide-spread labelling of egg chambers was elicited by [3H]-D-glucose and [3H]-D-galactose (e.g., nurse cells, follicle cells, chorion, vitelline membrane), but the labelling induced by [3H]-N-acetylmannosamine was restricted mainly to the endochorion. A possible role of microtubules in distribution and assembly of yolk spheres was inferred when colchicine, admixed to the culture medium (2–5 ppm), produced abnormal distribution and diminution in number of both alpha and beta yolk spheres. In addition to revealing previously unknown metabolic events of vitellogenesis, the results provide additional criteria for stage characterization as well as a means to specifically label certain macromolecules for purposes of isolation.
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    The fine structure of the bovine Descemet's membrane with special reference to biochemical nature (1982)
    Springer
    Cell & tissue research 226 (1982), S. 241-255 
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    ISSN: 1432-0878
    Keywords: Freeze-etching ; Cornea ; Descemet's membrane ; Basal lamina ; Collagen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A freeze-etch replica method combined with biochemical analyses was used to investigate the ultrastructural organization of the bovine Descemet's membrane. The freeze-etch replica observations revealed that the intact Descemet's membranes were composed of stacks of two-dimensionally arranged hexagonal lattices, in which four components were resolved; (1) round densities as nodes, (2) rod-like structures connecting the densities, (3) randomly oriented fine filaments within the lattices, and (4) amorphous materials covering the lattices. When the membranes were treated with sodium dodecyl sulfate (SDS) and mercaptoethanol, only the amorphous materials were solubilized. However, both the amorphous materials and rod-like structures disappeared in SDS-mercaptoethanol-urea-treated membranes. When the membranes were treated with a very low concentration (0.0005%) of collagenase, rod-like structures and round densities remained insoluble. If the concentration was raised to 0.01%, only the round densities persisted. Comparing these data with the amino acid analysis of each fraction, the following conclusions may be drawn: rod-like structures and fine filaments contain collagenous proteins of different solubility, while round densities and amorphous materials are non-collagenous in nature.
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    URL: http://dx.doi.org/10.1007/BF00218356
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    Interaction of the C1q component of complement and collagen with nucleic acids and polyanions (1980)
    Springer
    Bulletin of experimental biology and medicine 90 (1980), S. 1707-1709 
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    ISSN: 1573-8221
    Keywords: Collagen ; C1q component of complement ; nucleic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1007/BF00830455
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