title: Binding studies of [(18)F]-fluoride and polyphosphonates radiolabelled with [(111)In], [(99m)Tc], [(153)Sm], and [(188)Re] on bone compartments: a new model for the pre vivo evaluation of bone seekers?
abstract: BACKGROUND
  Although the first polyphosphonates were already introduced in the early 1970s, mechanisms involved in uptake still remain speculative. The present work aimed to establish a new method to rate the influence of various factors on the uptake and to evaluate new bone-seekers on these bone compartments.
  
  
  METHODS
  Radioactive-labelled diphosphonates and [(18)F]-fluoride were added to a vial containing hydroxyapatite (HA), collagen, or amorphous calcium phosphate (ACP) in 3 ml of Hanks' Balanced Salt Solution (HBSS). After incubation, these suspensions were filtered, the radioactivity was measured in the gamma-counter, and the percentage of irreversibly bound radioactivity was calculated.
  
  
  RESULTS
  Kinetic experiments revealed uptake increase over time for [(99m)Tc]-MDP and [(18)F]-fluoride on various amounts of matrix. After 120 min, static studies on HA yielded: [(99m)Tc]-EDTMP < [(188)Re]-/Re-EDTMP < [(99m)Tc]-/11 microl Re-EDTMP < [(99m)Tc]-/In-EDTMP < [(99m)Tc]-/15 microl Re-EDTMP < nca [(188)Re]-EDTMP < [(111)In]-/Re-EDTMP < [(111)In]-EDTMP < [(111)In]-/In-EDTMP < [(99m)Tc]-DPD < [(99m)Tc]-/80 microl Re-EDTMP < [(99m)Tc]-EDTMP "boiled" < [(99m)Tc]-/150 microl Re-EDTMP < [(153)Sm]-EDTMP < [(99m)Tc]-/11 microl Re-EDTMP "boiled" < [(18)F]-ions < [(99m)Tc]-MDP. Collagen showed very low uptake. Reincubation experiments suggest that bone tracers are irreversibly bound.
  
  
  CONCLUSIONS
  The presented method is rapid and feasible to examine the adsorption of radioactive-labelled substances on bone components. Correlations between our findings and published in vivo data support the application as a simple model.
authors.affiliation: Department of Nuclear Medicine, Medical University of Vienna, Vienna, Austria. markus.mitterhauser@akh-wien.ac.at
authors.forename: Markus
authors.initials: M
authors.lastname: Mitterhauser
authors.forename: Stefan
authors.initials: S
authors.lastname: Tögel
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wadsak
authors.forename: Leonhard-Key
authors.initials: LK
authors.lastname: Mien
authors.forename: Harald
authors.initials: H
authors.lastname: Eidherr
authors.forename: Karoline
authors.initials: K
authors.lastname: Wiesner
authors.forename: Helmut
authors.initials: H
authors.lastname: Viernstein
authors.forename: Kurt
authors.initials: K
authors.lastname: Kletter
authors.forename: Robert
authors.initials: R
authors.lastname: Dudczak
mesh_terms: D001859:Bone Neoplasms / Q000556:secondary*; D005459:Fluorides / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D063065:Organophosphonates / Q000378:metabolism*; D011868:Radioisotopes / Q000378:metabolism*
chemical_list: D063065:Organophosphonates; D011868:Radioisotopes; D005459:Fluorides