[1] Univ Sheffield, Mellanby Ctr Bone Res, Sheffield, S Yorkshire, England
[2] Univ Libre Bruxelles, Inst Interdisciplinary Res, Gosselies, Belgium
[3] Univ Sheffield, Kroto Res Inst, Sheffield, S Yorkshire, England
[4] Free Univ Brussels, Erasme Hosp, Dept Lab Med, B-1050 Brussels, Belgium