Technical innovation of Ervin G Erdös: A mechanical transducer for isotonic muscle contractions

Let me explain the principle of bioassay. It is an analytical method for determination of the relative strength (concentration or potency) of a substance by comparing its effect on a test organism (living animal, cells or tissues) with that of a standard preparation. Bioassays are used in pharmacology mainly to determine the concentrations of hormones or drugs, eg biologically active peptides, acetylcholine, catecholamines, prostaglandins, histamine and prostacyclin. However, there are other forms of bioassay in which one can use isolated tissues and determine actions of their nerves, such as the nerve to the diaphragm from rats. Bioassays may also be done in vivo in individual humans. The assessment of drug effects in humans is designated by clinical pharmacologists as a clinical trial. Such trials often require hundreds or sometimes thousands of patients in order to test efficacy and safety of any new drug before it can be marketed. If the human investigations produce unexpected results, quite different of those obtained in the animal experiments the trials must be redesigned, to examine why and how this occurred. There are many examples of how such discoveries resulted in new clinically useful medications (eg, discovery antihypertensive effect of beta-adrenergic blocking agents).6 Accordingly, the pharmacologists have the bioassays, as a tool, which help them in the discovery process. I wrote on the renowned pharmacologist Professor Ervin G Erdös and his scientific opus in my reminiscence article written on the occasion of his death in 2019.1 When I attended the Fourth International Congress in Pharmacology in Basel in 1969, Dr Ervin G Erdös invited me to join his laboratory. Thus, in April 1970, I arrived in Oklahoma City as a Fulbright Fellow to work with him for two years. Later on, as a visiting scientist I frequently worked in his research laboratories in Dallas and Chicago and we shared research interests through visits across the Atlantic between the former Yugoslavia and the United States.2, 3