1. From the Department of Medical Biochemistry, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia (Drs Vekic, Zeljkovic, Jelic-Ivanovic, Spasojevic-Kalimanovska, and Spasic and Mses Ivanisevic and Gojkovic); and the Institute for Pulmonary Diseases and Tuberculosis, Clinical Centre of Serbia, Medical Faculty, University of Belgrade, Belgrade, Serbia (Drs Videnovic-Ivanov and Vucinic-Mihailovic).