Blood samples for radioactivity measurements will be drawn at 0 (pre-infusion), 0.5, 1, and 2 hours post-infusion, and then 6 more samples will be drawn 1, 2, 3, 4 (or 6), 7±1, and 10±1 days post-infusion. In addition, when logistically feasible, an additional sample will be obtained 5 days post-infusion (optional).