[1] UNIV MANCHESTER, SCH BIOL SCI, MANCHESTER M13 9PT, LANCS, ENGLAND
[2] UNIV MANCHESTER, DEPT DENT MED, MANCHESTER M13 9PT, LANCS, ENGLAND
[3] UNIV MANCHESTER, DEPT SURG, MANCHESTER M13 9PT, LANCS, ENGLAND
[4] UNIV CALIF IRVINE, COLL MED, DEPT BIOL CHEM, IRVINE, CA 92717 USA
[5] INST CHILD HLTH, MOLEC MED UNIT, LONDON WC1N 3EH, ENGLAND