John Jacob Abel the position of chair of the department until he retired at the age of 75 in 1932. Ever since his early years in Europe, Abel showed great interest in isolating pure form of internal gland hormones. The first work that led to his international reputation as a pharmacologist and biochemist was the isolation of epinephrine from adrenal medulla. However, he was only able to isolate a monobenzoyl derivative of epinephrine. While he was improving his processes on decomposing the benzoyl derivative to obtain salts of epinephrine using saponification, a Japanese chemist J. Takamine, who had visited his lab, was able
John Leonora to have an activity indistinguishable from the isolated parotid hormone or the gene-expressed hormone. Meanwhile, it was discovered that the acinar cells of the parotid glands were apparently the source of the parotid hormone. Preliminary research suggested the parotid hormone not only regulates dental structures but also influences insulin secretion by the pancreas. These systemic effects have yet to be followed up. As Leonora stated in an undated letter, "I anticipate finding receptors [for the parotid hormone] in the odontoblasts in teeth, osteocytes in bone matrix, Islets of Langerhans…" John Leonora John Leonora (January 30, 1928 - February 17, 2006)