 Following her work in 1942 with David E. Green on amino- and hydroxy acid oxidases, and on a peptide form of p-aminobenzoic acid, she became interested in new aspects of nitrogen metabolism.In 1946, Ratner was hired as an assistant professor of pharmacology at the New York University School of Medicine.The following year she published a book on the mechanism of the formation of arginine from citrulline, a subject which would occupy her studies for the next four decades.