Document KRmwrQmn38D8N51O8zME52YpK

Ba l t imo r e Cit y Ho s p it a l s Fr e d e r ic G. Hu b b a r d d ir ec t o r 440 EASTERN AVENUE BAJ-TIMOREi MARYLAND 21224 October 27, 1971 IN REPLY REFER TO: Dr. Robert A. Kehoe Department of Environmental Health Kettering Laboratory, College of Medicine University of Cincinnati Eden and Sethesda Avenues Cincinnati, Ohio 4521 9 i Dear Dr.' Kehoe: Many thanks for your letter of October 18. I must say that i feel that my pediatric colleagues in Cincinnati surely do not know what they miss by failing to walk across the street. This is surely a problem that spans across the entire field of medicine. We are all, to a certain extent, hesitant to move out of our little niche. 1 have been reflecting on the future course of my own work during the past few months and have justabout reached the conclusion that I should concentrate a bit more in the area of porphyrin metabolism. In vitro studies strongly suggest that formed porphyrins, such as coproporphyrin and protoporphyrin, are biologically active compounds with toxic metabolic potentialities. Furthermore, they are photodynamic substances. I quite agree with you that insofar as heme synthesis in the blood is concerned, reduction in hemo globin is the significant feature. However, | think we must keep in mind that there are other heme enzymes in the various tissues and that, insofar as we know, each cell synthesizes its own heme for the formation of its own hemoproteins. Inhibition in heme formation or alteration in function within other types of cells certainly seem to me important areas for investigation, since alteration in heme synthesis In other tissues may be just as important to them as hemoglobin is to the function of blood. Again, many thanks for your recent letter. Yours sincerely. JJC:ov Chisolm. Jr. M.D.