[1] Hosp Med Sur, Mexico City, DF, Mexico
[2] Greer Labs Inc, Lenoir, NC USA
[3] IMSIE, Cologne, Germany
[4] Siglo XXI, Ctr Med Nacl, Mexico City, DF, Mexico
[5] Univ Fed Parana, BR-80060000 Curitiba, Parana, Brazil
[6] Fdn CIDEA, Buenos Aires, DF, Argentina
[7] Ctr Invest & Stat, Cologne, Germany