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  • 1
    ISSN: 1572-8773
    Schlagwort(e): EDTMP ; formation constants ; protonation constants ; samarium ; speciation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract 153Sm-EDTMP (ethylenediaminetetra(methylenephosphonic) acid) is of considerable interest as a bone therapeutic radiopharmaceutical but its properties in solution are not yet well characterized. The protonation constants of EDTMP and the formation constants of the complexes of Sm-EDTMP have accordingly been measured potentiometrically by glass electrode titrations at 25°C in 0.15 M NaCl. Six protonation constants (log β011 = 9.638, log β012 = 17.330, log β013 = 23.597, log β014 = 28.636, log β015 = 31.501, log β016 = 32.624) and the formation constants of the [Sm(EDTMP)H-1]6- (log β11-1 = 4.865), [SmEDTMP]5- (log β110 = 12.018), [Sm(EDTMP)H]4- (log β111 = 17.892) and [Sm(EDTMP)H2]3- (log β112 = 23.437) complexes were determined. Computer simulations indicate that the [SmEDTMP]5- and the hydroxy [Sm(EDTMP)H-1]6- species are the major Sm(III) complexes formed in blood plasma, which explains the high degree of localization in the kidney and urine observed in biodistribution studies. Calcium ions are probably the maior competitor for EDTMP in blood plasma. As the presence of secondary skeletal metastases results in a high rate of bone turnover, it is possible that the high concentration of calcium at these sites encourages localization of 153Sm-EDTMP.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-1327
    Schlagwort(e): Key words Raman microscopy ; Biomineralization ; Chiton ; Mollusc ; Iron
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract  In situ Raman spectroscopy, in combination with energy dispersive spectroscopy, has been used for the first time to determine the identities and locations, at the micron level, of mineral phases present in single chiton teeth that have been extensively mineralized. At the later stages of development the major lateral teeth of the chiton Acanthopleura hirtosa show characteristic spectroscopic evidence for the presence of lepidocrocite (γ-FeOOH), magnetite (Fe3O4), and an apatitic calcium phosphate. Goethite (α-FeOOH) and ferrihydrite (5 Fe2O3·9 H2O), which have been detected previously in teeth at the early stages of mineralization, were not detected in this mature tooth. The spatial distribution of these phases was determined, providing evidence for the presence of a discrete layer of lepidocrocite between the magnetite and apatite regions, illustrating the complexity of the biomineralization process. The technique of laser Raman microscopy is shown to be ideal for the examination of small biomineralized structures in situ, such as chiton teeth.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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