title: Assessment of chemical species of lead accumulated in tidemarks of human articular cartilage by X-ray absorption near-edge structure analysis.
abstract: A highly specific accumulation of the toxic element lead was recently measured in the transition zone between non-calcified and calcified normal human articular cartilage. This transition zone, the so-called `tidemark', is considered to be an active calcification front of great clinical importance. However, little is known about the mechanisms of accumulation and the chemical form of Pb in calcified cartilage and bone. Using spatially resolved X-ray absorption near-edge structure analysis (µ-XANES) at the Pb L(3)-edge, the chemical state of Pb in the osteochondral region was investigated. The feasibility of the µ-XANES set-up at the SUL-X beamline (ANKA synchrotron light source) was tested and confirmed by comparing XANES spectra of bulk Pb-reference compounds recorded at both the XAS and the SUL-X beamline at ANKA. The µ-XANES set-up was then used to investigate the tidemark region of human bone (two patella samples and one femoral head sample). The spectra recorded at the tidemark and at the trabecular bone were found to be highly correlated with the spectra of synthetic Pb-doped carbonated hydroxyapatite, suggesting that in both of these very different tissues Pb is incorporated into the hydroxyapatite structure.
authors.affiliation: Atominstitut, Vienna University of Technology, 1020 Wien, Austria.
authors.forename: Florian
authors.initials: F
authors.lastname: Meirer
authors.forename: Bernhard
authors.initials: B
authors.lastname: Pemmer
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Pepponi
authors.forename: Norbert
authors.initials: N
authors.lastname: Zoeger
authors.forename: Peter
authors.initials: P
authors.lastname: Wobrauschek
authors.forename: Simone
authors.initials: S
authors.lastname: Sprio
authors.forename: Anna
authors.initials: A
authors.lastname: Tampieri
authors.forename: Joerg
authors.initials: J
authors.lastname: Goettlicher
authors.forename: Ralph
authors.initials: R
authors.lastname: Steininger
authors.forename: Stefan
authors.initials: S
authors.lastname: Mangold
authors.forename: Paul
authors.initials: P
authors.lastname: Roschger
authors.forename: Andrea
authors.initials: A
authors.lastname: Berzlanovich
authors.forename: Jochen G
authors.initials: JG
authors.lastname: Hofstaetter
authors.forename: Christina
authors.initials: C
authors.lastname: Streli
mesh_terms: D002358:Cartilage, Articular / Q000737:chemistry*; D005270:Femur Head / Q000737:chemistry; D006801:Humans; D007854:Lead / Q000737:chemistry / Q000378:metabolism*; D010329:Patella / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy / Q000379:methods*
chemical_list: D007854:Lead