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
Prothoracicotropic hormone Prothoracicotropic hormone Prothoracicotropic hormone (PTTH) was the first insect hormone to be discovered. It was originally described simply as "brain hormone" by early workers such as Stefan Kopeć (1922) and Vincent Wigglesworth (1934), who realized that ligation of the head of immature insects could prevent molting or pupation of the body region excluded from the head if the ligation was performed before a critical age in the lifestage was reached. After a certain point the ligation had no effect and both sections of the insect would molt or pupate. However, implantation of a conspecific brain to a sessile ligated abdomen