The University of Pittsburgh Medical Center is on the client list of Los Angeles public relations guru Mike Sitrick, whose mission is to help the 20-hospital UPMC market itself worldwide. Sitrick's representatives last week toured the soon-to-open campus of the $625 million Children's Hospital in Lawrenceville. The new Children's is the latest project that warrants promotion by a national PR firm like Sitrick's, UPMC spokesman Paul Wood said.