Zach Horowitz has been named chief operating officer of MCA Entertainment Group, where he will focus on international operations, new technology and day-to-day management of the company under Chairman Al Teller. Horowitz was previously executive vice president at MCA.
* Ruth L. Otte, president and chief operating officer of Discovery Networks, is leaving the cable TV company to become president of Knowledge Adventure Inc., a fast-growing multimedia educational software company in La Crescenta. The company's former chief executive, Rod Turner, resigned in February. Otte, 45, was at Discovery for eight years. Otte's successor is programming executive Gregory B. Moyer.
* Brandon Bates has been named director of development at dick clark productions. Bates previously worked for comedian Martin Lawrence's You Go Boy Productions.
* Michael Forman has joined Brillstein/Grey Communications as director of television. Brillstein/Grey also announced a development deal with Paul Simms, who worked on "The Larry Sanders Show."
* Continuing the shake-up in its public relations department, ABC has named Mark R. Johnson vice president of network communications. Johnson, a longtime Washington press secretary and Capitol Hill aide, will oversee the network's West Coast operations.
* Annabelle Stevens has been named president of Warren Cowan & Associates.
* Richard S. Reisberg is the new president and chief operating officer of Trimark Holdings Inc.
* Mimi Wunderlich is director of sales promotions and publicity for Republic Pictures Entertainment.
* Stephen K. Peeples and David Dorn have been named co-directors of the Rhino Entertainment media relations department.
The company has also appointed executives to its Kid Rhino division. Torrie Dorrell is the director of Kid Rhino, Robin Frederick is director of A&R/Production, and Robin Davids is marketing coordinator.