As director of the county's Department of Health Services, Dr. Mitch Katz, 52, oversees Los Angeles' public hospitals and clinics, the healthcare of last resort for millions of low-income Angelenos. Los Angeles, the nation's second-largest city, has some 2 million uninsured residents. It has long had one of the most disorganized systems, too. Katz's primary aim though, and what he came to Los Angeles to do, is to steer low-income Angelenos away from the overburdened emergency rooms they've long relied upon and into primary care clinics where costs are lower, chronic diseases can be managed and problems, like a tumor, can be detected earlier.