Directors from a Central Pa. health system and its parent company have signed a nonbinding letter of intent to negotiate an affiliation with UPMC, according to a news release. Altoona Regional Health System, under parent company Central Pennsylvania Health Services Corporation, and UPMC have agreed to conditions of a prospective affiliation and will enter a due diligence period, Altoona Regional spokesman Dave Cuzzolina said. The final step would be the signing of a definitive affiliation agreement, he said.