High Quality Content by WIKIPEDIA articles! John Leonora (January 30, 1928 - February 17, 2006), is notable for his research into the critical role of hypothalamic "factors" for indirectly controlling the metabolism of such avascular tissues as the dental enamel, the dentin, and the Islands of Langerhans (pancreas). Most of his research was carried out during his 45 years as a faculty member at Loma Linda University and instructor at the university`s predecessor, the College of Medical Evangelists.