[1] Inst Biol & Med Expt, Lab Neuroendocrine Biochem, RA-1428 Buenos Aires, DF, Argentina
[2] Univ Buenos Aires, Fac Med, Dept Human Biochem, RA-1053 Buenos Aires, DF, Argentina
[3] Univ Buenos Aires, Fac Med, Dept Physiol, RA-1053 Buenos Aires, DF, Argentina
[4] Rockefeller Univ, Populat Council, New York, NY 10021 USA
[5] Univ Paris Sud, UMR Inserm 788, Le Kremlin Bicetre, France