 Michelle Olga Patricia Visser, working as a medical technician at Pretoria Hospital (now Steve Biko Academic Hospital), said that she discovered the anti-bacterial properties of dimethylformamide while conducting experiments to freeze animal hearts using this substance.In conjunction with her businessman husband, Jacques Siegfried "Zigi" Visser, she administered the drug to 11 patients without approval.They were rebuked for these actions and the South African Medicines Control Council blocked further human trials.