[1] Univ Puerto Rico, Sch Med, Dept Pharmacol, San Juan, PR 00936 USA
[2] Ctr Dis Control, Div Sci Lab, Atlanta, GA 30333 USA
[3] US FDA, Ctr Biol Evaluat & Res, Bethesda, MD USA
[4] NIST, Div Biotechnol, Gaithersburg, MD 20899 USA
[5] Ctr Quantitat Cytometry, San Juan, PR USA