Considerations about the present and future use of autoradiography

This Vth International Conference on Radioautography at the University of São Paulo follows the footsteps of earlier important contributions in this field by the present rector magnificus, Dr. Fava de Moraes, and the former chairman of the Department of Histology and Embryology and Dean of the Biomedical Sciences Institute, Dr. Carneiro. Thus, this conference is standing on traditional grounds. This conference provided an opportunity for the assessment of progress in the field of tissue autoradiography and its present potential as a tool in biomedical research at the University of São Paulo and other universities of Brazil, as well as at the international level. Although this international conference was numbered as “the Fifth”, it needs to be pointed out that several previous conferences on autoradiography or radioautography remained unnumbered and that the true number would most likely amount to ten or more. During the conference both terms “Radioautography” and “Autoradiography” have been used. While correct and uniform terminology should be observed and discussions about terminology generally encouraged, this specific topic has been addressed repeatedly in the literature. Since 1973, the U.S. National Library of Medicine decided in favor of “autoradiography”, which is the official singular subject heading for MEDLINE searches. A continued discussion of the semantics of these two terms thus is likely not fruitful. Both are linguistic hybrids of Latin and Greek. Their individual meaning is closely enough related to permit their parallel use without causing confusion. However, settlement for one term ultimately is to be advised. While not reviewing individual papers of this conference, notable were those presentations that applied autoradiography a) as a complementary approach, that is, in conjunction with alternate procedures (e.g., immunohistochemistry, biochemistry), b) as carefully controlled quantitative assessment of synthetic cellular processes (e.g., DNA, protein), and c) for providing maps especially for the brain and other highly complex organs as a guide for follow-up studies toward the understanding of mechanisms of action of autacoids and xenobiotics. Furthermore, it was apparent that autoradiographic studies, since generally more laborious and less expedient than biochemical studies, need to be planned with special care in terms of their experimental hypothesis and the significance of contributions of the expected results. Long exposure times must be considered and repeat, control and additional studies initiated in due time, often before the results of the experiment are known. Correspondence W.E.