OPERA STAR ENTERTAINS HOSPITAL PATIENTS: Frederick Jagel, Metropolitan Opera singer, who will appear in tonight's May Festival concert, paid a visit to the seventh floor of University hospital's tuberculosis unit last night to sing for patients. Jagel is pictured above as he was giving an hour's concert for the nurses and patients, among whom was Robert Johnstone, University student, who is a friend of Jagel. The two men's families are friends in New York. Guests at the concert were friends of Johnstone, Mr. and Mrs. Lee D. Young of Kimberly Rd. Jagel, accompanied by Ava Comin Case, sang Scottish and Irish ballads, "Sylvia," and an aria from "Carmen." He is returning to the hospital today and will autograph programs for the patients.