Associated PressActor Jeremy Piven at a movie screening last week, before he dropped out of the cast of "Speed-the-Plow," citing problems with mercury in his system.Jeremy Piven, best known for playing the blustery agent Ari Gold on HBO's "Entourage," revealed he was pulling out of a popular Broadway revival of "Speed-the-Plow" 10 weeks early because of high levels of mercury in his bloodstream, a result of a heavy sushi habit and a diet supplemented with Chinese herbs.We were taken aback by the news and talked with Piven's doctor, Carlon Colker, medical director of the Peak Wellness clinic in Greenwich, Conn., for more...