 The cancer stem cell was first identified in 1997 by Toronto researchers, who have since found stem cell associations in leukemia, brain tumors and colorectal cancer.Medical inventions developed at Toronto include the glycaemic index, the infant cereal Pablum, the use of protective hypothermia in open heart surgery and the first artificial cardiac pacemaker.The first successful single-lung transplant was performed at Toronto in 1981, followed by the first nerve transplant in 1988, and the first double-lung transplant in 1989.