1. Department of Clinical Research, Hairmyres Hospital, NHS, Lanarkshire G75 8RG, UK
2. School of Applied Sciences, Edinburgh Napier University, Edinburgh EH11 4BN, UK
3. Bridgeton Health Centre, Abercromby St, Glasgow G40 2DA, UK
4. Department of Surgery, Edinburgh Royal Infirmary, Edinburgh EH16 4SA, UK