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  • Hydroxyapatite  (6)
  • Springer  (6)
  • Annual Reviews
  • 1980-1984
  • 1975-1979  (6)
  • 1979  (3)
  • 1977  (3)
Collection
Keywords
Publisher
  • Springer  (6)
  • Annual Reviews
Years
  • 1980-1984
  • 1975-1979  (6)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Effect of proteoglycans on in vitro hydroxyapatite formation (1979)
    Springer
    Calcified tissue international 27 (1979), S. 75-82 
    Details
    ISSN: 1432-0827
    Keywords: Proteoglycans ; Hydroxyapatite ; Amorphous calcium phosphate ; Nucleation ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Well-characterized bovine nasal proteoglycan A1 fraction (aggregate) and proteoglycan D1 fraction (subunit) have been shown to be effective inhibitors of hydroxyapatite (HA) formation in two in vitro test systems: (a) the transformation of amorphous calcium phosphate (ACP) to crystalline HA, and, (b) the direct precipitation of HA from low-concentration calcium phosphate solutions. A1 or D1 in solution slowed the transformation kinetics in system (a) without affecting the time to the onset of conversion. In system (b), A1 or D1 in solution increased the time to the onset of HA formation without affecting the HA formation kinetics. In both test systems A1 was a more effective inhibitor than D1, although the difference was not great. In both systems the inhibitory effect was proportional to the A1 or D1 solution concentration. The action of solutions of low and high molecular weight neutral dextrans on both test systems showed that high molecular weight and/or extended spatial molecular conformation has a much stronger correlation with inhibitory ability than solution viscosity. Proteoglycans have been implicated as playing a role in regulating biological mineralization particularly in the epiphyseal growth plate. Our study suggests that just enzymatic cleavage of aggregate into subunit is not sufficient to allow mineralization to occur, since we find that D1 itself is a potent inhibitor of HA formation. Further degradation and/or removal of D1 appears to be necessary for calcification to take place.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441164
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  • 2
    Electronic Resource
    Electronic Resource
    X-ray diffraction of the calcified tissues inPolypterus (1979)
    Springer
    Calcified tissue international 28 (1979), S. 37-42 
    Details
    ISSN: 1432-0827
    Keywords: X-ray diffraction ; Hydroxyapatite ; Whitlockite ; Fish (Pisces) ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Pyrolyzed scales, fin spines, and bone from the ray-finned bony fishPolypterus (Actinopterygii) showed two mineral phases on X-ray diffraction: hydroxyapatite (HA), Ca5(PO4)3OH, and whitlockite, Ca3(PO4)2. The ratio of HA/whitlockite varied with the structure (scale, spine, bone) within each individual fish. The relative proportions of HA to whitlockite in pyrolyzed samples reflected the Ca/P ratio of the sample. Whitlockite appears after pyrolysis when the Ca/P is lower than 1.67. Among the five fish investigated, for each structure a general trend was noted. The proportion of HA relative to whitlockite increased with size (age) of the fish. Thus the smallest fish, a juvenile, exhibited a low Ca/P mineral in its calcified tissues, whereas the larger fish had progressively more HA and less whitlockite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441216
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of human salivary proteins on the precipitation kinetics of calcium phosphate (1979)
    Springer
    Calcified tissue international 28 (1979), S. 7-16 
    Details
    ISSN: 1432-0827
    Keywords: Salivary proteins ; Adsorption ; Hydroxyapatite ; Precipitation inhibitors ; Crystal growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Inhibition of calcium phosphate precipitation in saliva, and prevention of the formation of mineral accretions on tooth surfaces, has been ascribed to the existence of inhibiting salivary macromolecules. Marked reductions in the crystal growth rate of hydroxyapatite (HA) seeds were measured in supersaturated solutions containing either of two proline-rich proteins, PRP1 or PRP3, or statherin; the three macromolecules were isolated from human parotid saliva. The reductions were also observed when the HA seeds were pretreated with solutions of the macromolecules before adding them to the supersaturated calcium phosphate solution. This effect was very similar in the case of the two PRPs and it was directly related to the extent of adsorption site coverage of these proteins on the HA seeds. The effect of statherin was larger than anticipated from its adsorption behavior. However, comparison on the basis of number of moles adsorbed per unit area of HA shows that the PRP are more effective inhibitors than statherin. The macromolecule concentrations used were considerably lower than those in the salivery secretions, therefore these macromolecules could readily prevent mineral accretion on tooth surfaces through their adsorption onto the enamel surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441212
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  • 4
    Electronic Resource
    Electronic Resource
    An x-ray diffraction investigation of age-related changes in the crystal structure of bone apatite (1977)
    Springer
    Calcified tissue international 22 (1977), S. 219-226 
    Details
    ISSN: 1432-0827
    Keywords: Hydroxyapatite ; Bone ; X-ray Diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Evidence relating to the existence of crystalline bone mineral in vivo is considered, and bone apatite crystal structure investigated using an x-ray powder diffraction technique. Specimens of femoral compacta excised post-mortem from male and female subjects ranging from 3 1/2 years to 87 years of age have been studied. Values of the ratio c/a of bone apatite crystal cell axes for females are significantly higher (p〈0.05) than for males. Moreover, significant change of c/a with age is observed for males (p=0.0005) but not for females (p=0.30). Differences in c/a are interpreted as indicating substitution of constituent ions in the bone apatite crystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010360
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  • 5
    Electronic Resource
    Electronic Resource
    An in vitro and in vivo investigation of mellitate and ethane-1-hydroxy-1, 1-diphosphonate in calcium phosphate systems (1977)
    Springer
    Calcified tissue international 23 (1977), S. 53-60 
    Details
    ISSN: 1432-0827
    Keywords: Mellitic acid ; Ethane-1-hydroxy-1,1-diphosphonate ; Hydroxyapatite ; Calculus ; Instrumentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Comparisons of mellitate (MA) and ethane-1-hydroxy-1, 1-diphosphonate (EHDP) have been carried out in studies of enamel etching, calcium phosphate crystal growth and animal calculus deposition. In enamel etch studies at pH 5, 6, or 7 and after treatment times of 5 or 170 min, EHDP was less damaging to enamel surfaces than MA as determined by scanning electron microscopy, grazing angle electron diffraction, and quantitative etch solution analyses. Both MA and EHDP inhibited hydroxyapatite crystal growth, although EHDP was more effective than MA. The formation of a tricalcium mellitate surface phase is suggested as the basis of the MA crystal growth effect on apatite. Both MA and EHDP also inhibited rat calculus formation, but EHDP was more effective than MA. The relation between crystal growth inhibition, surface phase solubility, and anti-calculus activity is discussed and a generalized principal for determining an effective inhibitor of calculus is suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02012766
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  • 6
    Electronic Resource
    Electronic Resource
    An X-ray study of the paracrystalline nature of bone apatite (1977)
    Springer
    Calcified tissue international 24 (1977), S. 243-248 
    Details
    ISSN: 1432-0827
    Keywords: Paracrystallinity ; Hydroxyapatite ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary X-ray diffraction patterns from oriented bone sections show that the crystalline apatite content of untreated mature cortical bovine bone has, in fact, a paracrystalline structure (i.e., no long range order). There is anisotropy in both lattice distortions and the sizes of the coherently diffracting domains. The paracrystalline mean distance fluctuations, (g) were found to be 1.5 (±0.1)% and 2.9 (±0.2)% for the basal and prism planes respectively, the corresponding paracrystalline sizes being 220 (±20) and 70 (±10) Å. The paracrystalline structure became more ordered above 600°C, suggesting the association of hydroxyl and possibly carbonate and other ions with the paracrystalline structure. The paracrystalline model for bone apatite helps explain anomalies between X-ray and electron microscope measurements of crystal size and also some of the biological functions of the crystalline apatite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02223323
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