Several of IBD's sector leaders leaned on the throttle Wednesday as the major indexes notched big gains. Intuitive Surgical (ISRG), a rock star among sector leaders this week, gained 16.52 Wednesday to 383.95. It's now up 10% for the week and 5% above the 367.10 buy point it cleared Tuesday. The maker of robotic surgical systems reports earnings after Thursday's close. An even bigger gain came from Nu Skin (NUS), which rocketed 2.21 to 31.65 in