1. Department of Pathology, The University of the West Indies, Mona Campus, Kingston 7, Jamaica
2. The Transitional Year Programme, University of Toronto, Toronto, ON M5S 2E8, Canada
3. Department of Life Sciences, Texas A&M University, Corpus Christi, TX 78412, USA
4. Department of Health Sciences, Texas A&M University, Corpus Christi, TX 78412, USA