Brazilian Journal of Medical and Biological Research, Volume: 42, Issue: 6, Pages: 487-493, Published: JUN 2009 Brazilian Journal of Medical and Biological Research v.42 n.6 2009 Brazilian Journal of Medical and Biological Research Associação Brasileira de Divulgação Científica (ABDC) instacron:ABDC Brazilian Journal of Medical and Biological Research, Vol 42, Iss 6, Pp 487-493 (2009)