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  • Articles  (28)
  • Phosphate  (28)
  • Springer  (28)
  • American Association for the Advancement of Science
  • American Chemical Society
  • American Geophysical Union
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  • 2000-2004  (2)
  • 1970-1974  (26)
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  • Physics  (26)
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  • Articles  (28)
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  • Springer  (28)
  • American Association for the Advancement of Science
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  • 1
    Electronic Resource
    Electronic Resource
    Effect of maize root mucilage on phosphate adsorption and exchangeability on a synthetic ferrihydrite (2000)
    Springer
    Biology and fertility of soils 31 (2000), S. 525-532 
    Details
    ISSN: 1432-0789
    Keywords: Key words Ferrihydrite ; Phosphate ; Polygalacturonic acid ; Root mucilage ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  This study was conducted to determine the influence of root mucilage (RM) from Zea mays, polygalacturonic acid (PGA), and galacturonic acid (GA), on the adsorption, desorption, and exchangeability of orthophosphate (P) on a synthetic ferrihydrite in deionized water. The adsorption rate and affinity on the oxide decreased in the order P〉GA〉PGA≥RM. The results suggest that P and GA were adsorbed by ligand exchange on Fe-OH surface sites, while RM and PGA might in addition also be adsorbed by hydrogen and van der Waals bonds to the oxide surface. Whereas P and GA could be adsorbed at sites located inside the micropores of ferrihydrite aggregates, PGA and RM probably remained on the external surfaces because of their large molecular weight. The preliminary adsorption of organic compounds decreased the subsequent P adsorption. The larger decrease of P adsorption occurred when dry ferrihydrite powder was directly added to the RM/water suspension. This effect was due to the flocculation of ferrihydrite aggregates, which limited the transport of P to the adsorption sites. Preliminary adsorption of GA also decreased P adsorption, because both compounds competed for the same Fe-OH sites. The ability of the organic compounds to desorb P from the ferrihydrite was not very pronounced and decreased in the order GA〉PGA≥RM. The preliminary adsorption of organic compounds on the oxide resulted in an increase in isotopically exchangeable P in 300 min compared to the treatment without organic compounds. However, because of its higher affinity for the oxide surface, P exchangeability was not modified when P was added before the organic compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740000206
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  • 2
    Electronic Resource
    Electronic Resource
    Precipitation of calcium phosphates from electrolyte solutions (1972)
    Springer
    Calcified tissue international 10 (1972), S. 82-90 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Precipitation ; Kinetics ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La cinétique de la formation et de la transformation des précipités de phosphate de calcium, obtenus en mélangeant de volumes égaux de solutions à 6×10−3 M de calcium total et/ou phosphate total est étudiée à 25°C. Les solutions de phosphate sont préajustées à un pH de 7.4. Les changements de pH et de turbidité des solutions sont suivis simultanément en fonction du temps. Les précipités sont isolés à des intervalles de temps variables et caractérisés par diverses méthodes physico-chimiques. Initialement un précipité avec un rapport molaire Ca/P de 1.5, amorphe aux rayons X et en diffraction électronique, est formé. Le spectre IR indique la présence de PO 4 3− et de HPO 4 2− . Après une période métastable, on observe la précipitation d'un matériel cristallin dans ou sur la phase amorphe. Vingt quatre heures après préparation de l'échantillon les précipités présentent surtout les caractères du phosphate octocalcique.
    Abstract: Zusammenfassung Die Kinetik der Bildung und Transformation von Calciumphosphat-Niederschlägen wurde bei 25°C untersucht. Es wurden dazu gleiche Volumen von Lösungen gemischt, bei einer Konzentration von 6×10−3M totales Calcium und/oder totales Phosphat. Die Phosphatlösungen wurden zuerst auf pH 7,4 eingestellt. Veränderungen des pH und Trübung der Lösungen wurden gleichzeitig als eine Funktion der Zeit aufgezeichnet. Niederschläge wurden in verschiedenen Zeitintervallen isoliert und mit verschiedenen physiko-chemischen Methoden charakterisiert. Am Anfang wurde ein Niederschlag mit einem molaren Ca/P-Verhältnis von 1,5, im Röntgenbild und in der Elektronendiffraktion amorph, gebildet. Infrarotspektren deuteten die Anwesenheit von PO 4 3− - und HPO 4 2− -Ionen an. Nach einer metastabilen Periode erfolgte ein Niederschlag aus kristallinem Material innerhalb oder auf der amorphen Substanz. 24 Std nach der Herstellung der Proben zeigten die Niederschläge in der Hauptsache die Charakteristiken von Octocalciumphosphat.
    Notes: Abstract The kinetics of the formation and transformation of calcium phosphate precipitates obtained by mixing equal volumes of solutions, 6×10−3 M in total calcium and/or total phosphate was investigated at 25°. The phosphate solutions were preadjusted to pH 7.4. Changes of the pH and turbidity of the solutions were followed simultaneously as a function of time. Precipitates were isolated at various time intervals and characterized by different physicochemical methods. Initially a precipitate with a molar Ca/P ratio of 1.5, amorphous to X-ray and electron diffraction was formed. IR spectra indicated the presence of PO 4 3− and HPO 4 2− ions. After a period of metastability, precipitation of a crystalline material within or upon the amorphous matter occurred. Twenty four hours after sample preparation the precipitates showed mainly the characteristics of octacalcium phosphate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02012538
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetic reactions of calcium, phosphate, and fluoride ions at the enamel surface-solution interface (1972)
    Springer
    Calcified tissue international 10 (1972), S. 113-127 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Fluoride ; Tooth ; Enamel ; Kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les surfaces d'émail dentaire sont confrontées avec des solutions de calcium et phosphate, qui y recirculent. Les réactions cinétiques au niveau des surfaces en calcium, phosphate, fluorure et ions hydrogène sont déterminées dans des solutions à concentrations en ions fluor constantes (0.012, 0.025, 0.050, 0.250 ou 0.500 mM/l) et/ou à pH constant (6.8, 7.0, 7.2 ou 7.4). Les vitesses de réactions des ions calcium, phosphate, hydrogène et fluorures augmentent dans les conditions suivantes: 1) augmentation de la surface d'émail, 2) augmentation des vitesses d'écoulement au niveau des surfaces, 3) augmentation du pH de la solution et 4) augmentation de la concentration en ion fluorure. Les vitesses presque proportionnelles des réactions mesurées simultanément indiquent la formation de minéraux apatitiques à la surface de l'émail pendant tout le temps de contact solide-solution.
    Abstract: Zusammenfassung Oberflächen von Zahnschmelz wurden mit konstant zirkulierenden Lösungen, welche Calcium und Phosphate enthielten, equilibriert. Die kinetischen Oberflächenreaktionen von Calcium-, Phosphat-, Fluori- und Wasserstoff-Ionen wurden in Lösungen mit konstanten Fluoridkonzentrationen (0,012, 0,025, 0,050, 0,250 oder 0,500 mM/l) und/oder konstantem pH (6,8, 7,0, 7,2 oder 7,4) bestimmt. Die Reaktionsgeschwindigkeiten dieser Ionen an der Grenze zwischen fester und flüssiger Phase erhöhten sich unter folgenden Bedingungen: 1. Vergrößerung der Schmelzoberfläche; 2. Erhöhung der Geschwindigkeit der der Oberfläche zugeführten Lösungen; 3. Erhöhung des pH der Lösung; 4. Erhöhung der Fluoridionenkonzentration in der Lösung. Die beinahe proportionalen Geschwindigkeiten der gleichzeitig gemessenen Reaktionen deuteten darauf hin, daß auf den Schmelzoberflächen während der ganzen Equilibrierungszeit Apatitminerale gebildet wurden.
    Notes: Abstract Surfaces of tooth enamel were interfaced with recirculating solutions containing calcium and phosphate. The kinetic interfacial reactions of calcium, phosphate, fluoride, and hydrogen ions were determined in solutions of constant fluoride ion concentrations (0.012, 0.025, 0.050, 0.250, or 0.500 mM/l) and /or constant pH (6.8, 7.0, 7.2, or 7.4). The rates of the calcium, phosphate, fluoride, and hydrogen ion reactions at the solid-solution interface increased under the following conditions: (1) increase of the enamel surface area; (2) increase of the rates of solution flow to the interface; (3) increase of solution pH; and (4) increase of the solution fluoride ion concentration. The nearly proportional rates of the concurrently measured reactions indicated the formation of apatitic minerals on the enamel surfaces throughout the time of solid-solution interface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02012541
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of age on bone calcium and phosphate metabolism in organ culture (1974)
    Springer
    Calcified tissue international 16 (1974), S. 89-92 
    Details
    ISSN: 1432-0827
    Keywords: Age ; Bone culture ; Calcium ; Phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Calvaria taken from mice aged 0, 1, 3 and 5 days were cultured for 48 h, in control medium (no added hormone), or in the presence of PTH (0.5 U/ml) or CT (50 mCl/ml). In the control group, there was a shift from net uptake of Ca and P (0- and 1-day bones) to net release (5-day bones). CT-treated bones of all ages took up Ca from the culture medium, but the percentage uptake declined with increasing age. Bones exposed to PTH released Ca and P to the culture medium, regardless of age. The changes with increasing age may be related to an increase in mineralization and other aspects of maturation in these bones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02008215
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  • 5
    Electronic Resource
    Electronic Resource
    Serum calcium, phosphate and alkaline phosphatase and morphometric bone examinations in 30 patients with renal insufficiency (1974)
    Springer
    Calcified tissue international 16 (1974), S. 129-138 
    Details
    ISSN: 1432-0827
    Keywords: Serum ; Calcium ; Phosphate ; Alkaline phosphatase ; Kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract In 30 patients with chronic renal insufficiency (16 non-dialysed and 14 on dialysis) serum calcium, phosphate and alkaline phosphatase were determined and, in a crest biopsy specimen, morphometric determinations of bone qualities were calculated. A positive correlation was established between serum alkaline phosphatase, the osteoblast surface and the active resorption surface in both dialysed and non-dialysed patients. A positive correlation was also established between the osteoblast surface and the active resorption. In the non-dialysed patients a negative correlation was established between serum calcium and the osteoid surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02008218
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  • 6
    Electronic Resource
    Electronic Resource
    Effects ofSolanum malacoxylon on embryonic bonein vitro and on isolated mitochondria (1974)
    Springer
    Calcified tissue international 16 (1974), S. 219-226 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Phosphate ; ATP ; Calcium ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract An active constituent of the leaves ofSolanum malacoxylon (SM) is shown to promote calcium resorption and citrate production in embryonic chick frontal bone culturedin vitro. When injected into rats, SM reduces the ATP content of liver and kidneys. This phenomenon may be related to the ability of SM to stimulate mitochondrial ATPase activity at pH 9.4. SM significantly reduces the concentration of phosphate necessary to alter the uptake of calcium and respiration of siolated mitochondria. The data suggest that SM influences calcium and phosphate metabolism by affecting ion movements into and out of mitochondria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02008229
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  • 7
    Electronic Resource
    Electronic Resource
    An observation on the analysis of urinary calculi by infrared spectroscopy (1971)
    Springer
    Calcified tissue international 7 (1971), S. 232-240 
    Details
    ISSN: 1432-0827
    Keywords: Calculus ; Infrared ; Spectroscopy ; Calcium ; Oxalate ; Phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les noyaux centraux de 500 calculs urinaires, comportant 421 calculs des voies urinaires supérieures, 64 calculs des voies urinaires inférieures et 15 calculs de la prostate ont été analysés au Japon par spectroscopie infrarouge. Les résultats de cette analyse indiquent que 50,8% des calculs sont composés d'un mélange d'oxalate de calcium et phosphate de calcium: 17,4% d'oxalate de calcium simple; 17,4% de phosphate de magnésium ammoniaqué, mélangé au phosphate de calcium et probablement aussi au carbonate de calcium: 4,4% d'acide urique et d'urate avec ou sans phosphate de calcium ou d'oxalate de calcium: 3,2% de phosphate de calcium: 1,0% de cystine et 0,2% (un cas) constitué de protéine. Sur 119 calculs, constitués d'oxalate-phosphate, les rapports de l'oxalate de calcium et du phosphate de calcium sont mesurés á l'aide des spectres infra-rouges et les rapports de 53 régions corticales de ces calculs ont été déterminés et comparés è ceux des régions nucléaires centrales. Il apparait ainsi que le noyau des calculs d'oxalate phosphate contient de plus grandes quantités de phosphate de calcium.
    Abstract: Zusammenfassung In Japan wurden die zentralen Nuclei von 500 Nierensteinen mittels Infrarotspektroskopie untersucht. Es handelte sich dabei um 421 Steine aus den oberen Harnwegen, 64 Steine aus den unteren harnwegen und 15 Prostatasteine. Die Analysen ergaben folgende Resultate: 50,8% der Steine setzten sich aus einem Gemisch von Calciumoxalat und Calciumphosphat usammen; 17,4% enthielten nur Calciumoxalate; 17,4% bestanden aus einem Gemisch von Magnesiumammoniumphosphat mit Calciumphosphat und vermutlich auch Calciumcarbonat; 4,4% enthielten Harnsäure und Urate mit oder ohne Calciumphosphat oder Calciumoxalat; 3,2% bestanden aus Calciumphosphat; 1,0% aus Cystin und 0,2% (ein Fall) aus Protein. Bei 119 Phosphatoxalatsteinen wurde das Verhältnis von Calciumoxalat zu Calciumphosphat aus den Kurven der erhaltenen Infrarotspektra bestimmt. Dieses Verhältnis wurde ebenfalls für die äußere Schicht von 53 solcher Steine berechnet und mit dem Wert der zugehörigen zentralen Nuclei verglichen. Aus diesen Resultaten geht hervor, daß die Nuclei der Phosphatoxalatsteine größere Mengen von Calciumphosphat enthalten.
    Notes: Abstract The central nuclei of 500 urinary calculi in Japan, including 421 calculi of upper urinary tracts, 64 calculi of lower urinary tracts and 15 prostatic calculi, were analysed by infrared spectroscopy. The results of analysis revealed that 50.8% of calculi were composed of mixed calcium oxalate-calcium phosphate; 17.4%, simple calcium oxalate; 17.4%, magnesium ammonium phosphate mixed with calcium phosphate, and probably also with calcium carbonate; 4.4%, uric acid and urate with or without calcium phosphate or calcium oxalate; 3.2%, calcium phosphate; 1.0%, cystine; and 0.2% (one case) were composed of protein. Of 119 oxalate-phosphate calculi the ratios of calcium oxalate to calcium phosphate were measured on the chart of infrared spectra, and also the ratios of 53 cortices taken from these calculi were measured and compared to the ratios of these central nuclei. The results showed that the nuclei of oxalate-phosphate calculi contained greater amounts of calcium phosphate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02062610
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  • 8
    Electronic Resource
    Electronic Resource
    Rio Tinto estuary (Spain): 5000 years of pollution (2000)
    Springer
    Environmental geology 39 (2000), S. 1107-1116 
    Details
    ISSN: 1432-0495
    Keywords: Key words Sediment pollution ; Massive sulfides ; Phosphate ; Open-pit mining ; Estuary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Mining of massive sulfide deposits in southwestern Spain extending back to the Copper and Bronze Ages has resulted in the pollution of the Rio Tinto fluvial-estuarine complex, the site of Columbus' departure for the New World in 1492. Additional sources of potential pollution include the large industrial complex at Huelva near the lower portion of the estuary. Extensive analysis of surface sediment samples and cores has established that there are no geographic trends in the distribution of the pollutants, which include Cu, Fe, Pb, Zn, Ti, Ba, Cr, V and Co. These data have, however, demonstrated that tidal flux within the estuary carries phosphorus and perhaps other elements from the industrial complex at Huelva to the tidal limit of the system, several kilometers upstream from the discharge site. Radiometric analysis of short cores shows that sedimentation rates over at least the past couple of centuries have been about 0.3 cm/year. These data and that from a single deep core demonstrate that the estuary was polluted from mining activity long before the large-scale operations began in the late nineteenth century.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002549900096
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  • 9
    Electronic Resource
    Electronic Resource
    The migration of F−, OH− and O2− ions in apatites (1973)
    Springer
    Calcified tissue international 13 (1973), S. 47-52 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Caries ; Fluoride ; Diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les énergies de déplacement des ions F−, OH− et O2− dans la maille réticulaire des apatites ont été calculées en utilisant un modèle cristallin de Born. Une attention particulière a été apportée au déplacement parallèle de l'axe c par un mécanisme de lacune. Contrairement à la plupart des cristaux ioniques, la barrière opposée au déplacement est électrostatique plutôt que répulsive. L'énergie de déplacement d'un cristal donné est la plus faible pour F−, intermédiaire pour O2−, et la plus élevée pour OH−.
    Abstract: Zusammenfassung Die Bewegungsenergien von F−, OH− und O2−-Ionen im Apatitgitter wurden berechnet, indem ein Born-Modell des Kristalles verwendent wurde. Die Untersuchung wurde auf die Migration beschränkt, welche durch einen Vakanzmechanismus parallel zur C-Achse verläuft. Im Gegensatz zu den meisten Ionenkristallen hat die Migrationsbegrenzung eher einen elektrostatischen als einen abstoßenden Charakter. Es wurde festgestellt, daß die Migrationsenergie in einem Kristall am kleinsten für F−, dazwischen liegend für O2− und am größten für OH− ist.
    Notes: Abstract The energies of motion of F−, OH− and O2− ions in the apatite lattice have been calculated using a Born model of the crystal. Attention was confined to migration parallel to the c-axis by a vacancy mechanism. In contrast to most ionic crystals the barrier to migration is electrostatic rather than repulsive in character. It is found that the migration energy in a given crystal is least for F−, intermediate for O2− and largest for OH−.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02015395
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  • 10
    Electronic Resource
    Electronic Resource
    Inhibition of calcium phosphate mineral growth by proteoglycan aggregate fractions in a synthetic lymph (1973)
    Springer
    Calcified tissue international 13 (1973), S. 1-10 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Proteoglycan ; Electrolyte ; Physiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'effet des protéoglycanes sur la croissance de minéraux d'ensemencement dans un milieu synthétique est étudié sous l'angle de la régulation de l'ossification enchondrale. Les protéoglycanes sont isolés à partir ducartilage nasal bovin à l'aide de trois méthodes publiées. A l'aide de chacune de ces méthodes, deux fractions sont isolées qui se distinguent par la présence ou l'absence de composés qui se sédimentent rapidement par ultracentrifugation analytique. Chaque fraction est étudiée en fonction de sa possibilité d'inhiber la croissance minérale dans un milieu tamponné synthétiquein vitro. A des concentrations de protéoglycanes qui se retrouvent dans le liquide interstitielle de la métaphyse de rats de 6 à 7 semaines, les fractions contenant des composés qui se sédimentent rapidement, inhibent la croissance minérale; alors que les fractions contenant des composés, qui sédimentent lentement, ainsi qu'une glycoprotéine (protéine de liaison) n'ont pas d'activité d'inhibition dans ces systèmes. La comparaison de la capacité de fixation du calcium de certaines fonctions de protéoglycanes ainsi que leur effet sur la diminution de l'activité calcique dans des conditions de dialyse équilibrées ne montrent aucune différence sur le comportement des fractions de protéoglycanes comportant des produits sédimentant rapidement ou lentement. Un degré plus élevé de protection des minéraux naissants, fournie par les portions protéiques adjacentes de protéoglycanes agrégés, pourrait être responsable de l'action d'inhibition de croissance minéralein vitro de protéoglycanes sédimentant rapidement.
    Abstract: Zusammenfassung Die Wirkung von Proteoglykanen auf das Wachstum von Impfkristallen in synthetischer Lymphe wurde, mit besonderer Berücksichtigung der Regulation von endochondraler Verkalkung, studiert. Die Proteoglykane wurden nach drei publizierten Methoden aus dem Nasenknorpel des Rindes isoliert. Bei jeder Methode wurden zwei Fraktionen abgetrennt, welche sich bei der analytischen Ultrazentrifugation in bezug auf An- oder Abwesenheit von schnellsedimentierenden Komponenten unterschieden. Jede Fraktion wurde darauf geprüft, ob siein vitro das Mineralwachstum in einer gepufferten synthetischen Lymphe zu hemmen vermochte. Bei Proteoglykan-Konzentrationen, wie sie in der interstitiellen Flüssigkeit endochondraler Platten von 6 bis 7 Wochen alten Ratten vermutet werden, hatten diejenigen Fraktionen, welche schnell-sedimentierende Komponenten enthielten, eine Hemmwirkung auf das Mineralwachstum; Fraktionen mit langsam-sedimentierenden Komponenten und mit einem Glycoprotein („link protein”) hingegen zeigten in diesen Systemen keine Hemmwirkung. Der Vergleich der Calcium-bindenden Fähigkeit bestimmter Proteoglykan-Fraktionen sowie deren vereinte Wirkung auf die Herabsetzung der Calcium-Aktivität unter Bedingungen der Gleichgewichtsdialyse zeigte keine Unterschiede im Verhalten von Proteoglykan-Fraktionen, die reich an schnell-sedimentierenden Komponenten waren im Gegensatz zu Fraktionen, welche ausschließlich langsam-sedimentierende Komponenten enthielten. Die Hemmwirkung von schnell-sedimentierenden Proteoglykanen auf das Mineralwachstumin vitro wird mit folgender Hypothese erklärt: Die Mineralkeime werden in zunehmendem Maße durch angrenzende Proteinkerne angehäufter Proteoglykane geschützt.
    Notes: Abstract The effect of proteoglycans on growth of seeding minerals in synthetic lymph was studied with special reference to regulation of endochondral calcification. Proteoglycans were isolated from bovine nasal cartilage by three published methods. By each method two fractions were separated which differed in respect to presence or absence of fast-sedimenting components on analytical ultracentrifugation. Each fraction was tested for its capacity to inhibit mineral growth in a buffered synthetic lymphin vitro. At concentrations of proteoglycans estimated to occur in the interstitial fluid of endochondral plates from 6- to 7-week-old rats, the fractions containing fast-sedimenting components were inhibitory to mineral growth; whereas fractions containing the slow-sedimenting components and a glycoprotein (link protein) had no inhibitory activity demonstrable in these systems. Comparison of calcium-binding capacity of certain proteoglycan fractions as well as their computed effect upon reduction of calcium activity under conditions of equilibrium dialysis revealed no differences in the behavior of a proteoglycan fraction rich in fast—as opposed to fractions composed entirely of slow-sedimenting components. An increased degree of shielding of mineral embryos provided by adjacent protein cores of aggregated proteoglycans is hypothesized to explain the inhibitory action of fast-sedimenting proteoglycans on mineral growthin vitro.
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    URL: http://dx.doi.org/10.1007/BF02015390
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