Frederick Banting in the blood which was then excreted in urine. Attempts to extract insulin from ground-up pancreas cells were unsuccessful, likely because of the destruction of the insulin by the proteolysis enzyme of the pancreas. The challenge was to find a way to extract insulin from the pancreas prior to its being destroyed. Moses Barron published an article in 1920 which described experimental closure of the pancreatic duct by ligature; this further influenced Banting's thinking. The procedure caused deterioration of the cells of the pancreas that secrete trypsin which breaks down insulin, but it left the islets of Langerhans intact. Banting
Frederick Banting medicine and, in 1919–1920, was Resident Surgeon at The Hospital for Sick Children. Banting was unable to gain a place on the hospital staff and so he decided to move to London, Ontario to set up a medical practice. From July 1920 to May 1921, he continued his general practice, while teaching orthopedics and anthropology part-time at the University of Western Ontario in London because his medical practice had not been particularly successful. From 1921 to 1922 he lectured in pharmacology at the University of Toronto. He received his M.D. degree in 1922, and was also awarded a gold medal.