[1] Univ Sheffield, Div Clin Sci, Sheffield S10 2TN, S Yorkshire, England
[2] Univ Sheffield, Sch Hlth & Related Res, Sheffield S10 2TN, S Yorkshire, England
[3] Sheffield Hallam Univ, Ctr Biomed Res, Sheffield S1 1WB, S Yorkshire, England
[4] Univ Manchester, Endocrine Sci Grp, Manchester M13 9PL, Lancs, England
[5] Christie Hosp, Manchester, Lancs, England
[6] INSERM, Fac Med Necker, Unite 344, F-75730 Paris 15, France