0120-4157 0120-4157 S0120-41572018000400479 10.7705/biomedica.v38i4.3754 Chile Chile Chile 00 12 2018 00 12 2018 38 4 479 485

1 National Institutes of Health 1987 79 Sept 29 to Oct 1, 1986 292-9 2 2011 12 124-32 3 2005 52 1127-46 4 2004 89 1043-8 5 2002 19 11-6 6 2008 79 163-71 7 2007 17 188-92 8 2009 71 412-8 9 2006 77 267-73 10 2007 46 258-62 11 2007 42 393-6 12 2008 47 953-8 13 2004 93 847-9 14 2004 30 337-44 15 2012 28 17-21 16 2009 24 709-13 17 2013 163 94-9 18 2016 137 19 2017 63 39-41