 Rosenfeld was interested in the study of biochemistry of the action of snake venom toxins in animals and humans, particularly those of the Bothrops family (lancehead or jararaca), which is extremely abundant all over Brazil and which caused a great number of accidents and deaths at his time.Among other things, he investigated the action of the venom of this snake on fibrinolysis and blood coagulation.In 1948, as part of a research team at the Instituto Biológico, Dr. Rosenfeld co-discovered, with two other Brazilian physiologists and pharmacologists, Drs.