1. University Dental Hospital of Manchester, National Public Health Institute, Higher Cambridge Street, M15 6FH, Manchester
2. Department of Bacteriology, Oral Biology and Pathology, National Public Health Institute, School of Dentistry, Helsinki
3. University of Queensland, University of Manchester, Queensland, 4072, St Lucia
4. Mass Spectrometry Laboratory, Chemistry Department, University of Manchester, Brunswick Street, M13 9PL, Manchester
5. RM Alden Research Laboratory, Santa Monica-UCLA Medical Center, CA, 90404, Santa Monica