J.D. Swartz has been appointed president of Worrell Newspapers Inc. and Worrell Broadcasting. He has been senior vice president of the company since 1979. Swartz replaces Thomas Worrell Jr., who will continue as chairman of the board. The company publishes 23 daily and 14 weekly or biweekly newspapers and operates three television stations in 18 states and the U.S. Virgin Islands.

Harold S. Trimmer has been named vice president of international development for MCI Corp. He was previously vice president and general counsel for Garfinckel, Brooks Brothers, Miller & Rhoads Inc. in Washington. Trimmer will be responsible for coordination at MCI of the company's pending acquisition of WUI Inc., the parent company of Western Union International.

In two related developments, J. Robert Harcharik has been named vice president of data services for MCI. He was previously president of the Tymnet Inc. division of Tymshare Inc.

Susan D. Jones has become manager of public relations at MCI. Jones had been manager of publications for Potomac Electric Power Co.

Harry Linowes, managing partner of the accounting firm Leopold & Linowes, has been elected to the advisory board of WAMU-FM.

Thursa C. Thomas has been named director of public affairs for WJLA-TV. In this position, she will be serve as executive producer for all of the station's public affairs and community service programs. Thomas was formerly producer of "Good Morning Washington."