[1] Stanford Univ, Dept Med, Stanford Prevent Res Ctr, Stanford, CA 94305 USA
[2] Univ Calif San Francisco, Div Clin Pharmacol & Expt Therapeut, Dept Med, San Francisco, CA 94143 USA
[3] Univ Calif San Francisco, Div Clin Pharmacol & Expt Therapeut, Dept Bioengn, San Francisco, CA 94143 USA
[4] Univ Calif San Francisco, Div Clin Pharmacol & Expt Therapeut, Dept Therapeut Sci, San Francisco, CA 94143 USA