July 21, 1987

LEAD: The NBC radio networks, founded 61 years ago as the first national network but undercut by the age of television, will be sold for $50 million, NBC said today.

LEAD: Every zoo needs a Sue Mitschke, 20 years an animal keeper. ''I'm a swing keeper,'' she said, filling a bucket of delicious high fiber pellets for the llama. ''What a love, what a love if this llama's upset - she'll spit in your face. Good girl! Good girl!''

LEAD: In 1983, when American Airlines instituted a wage scale for newly hired workers that was lower than that for other employees, executives at other airlines and in other industries thought it was a great idea. They reasoned that by taking the same approach they would be able to reduce their labor costs significantly without having to fight for major concessions from longer-term workers and their unions.

LEAD: WHILE some astrophysicists work on high-velocity field dwarfs or magnetohydrodynamic solitons, others have been brooding lately about an older problem: Why is the night sky dark?

LEAD: Hospitals here in New Jersey's largest city are so strained by the number of AIDS patients that they are trying to establish the state's first hospital for people with the deadly disease.

LEAD: Companies

LEAD: In an effort to ease New York City's severe housing shortage, the agency that is the nation's largest investor in home mortgages will make use of a new Federal tax incentive to help renovate 1,000 rental apartments for low- and moderate-income people in New York City.

LEAD: Kuwait's Prime Minister sought today to dissociate his country from any hostilities in which the United States might become involved while protecting Kuwaiti tankers in the Persian Gulf.

LEAD: Longtime residents of this city like to say that the best thing about Jerusalem is the road to Tel Aviv.

LEAD: Merrill Lynch & Company yesterday reported the full extent of the mammoth bond trading losses it suffered last April, saying the gross loss totaled $377 million, $102 million more than previously disclosed. The brokerage firm announced, though, that, as a result of several large, one-time gains, it produced an overall profit in the second quarter.

LEAD: After the disastrous fire in 1977 that nearly put him out of business, Nick Jutis reopened Luigi's Continental Restaurant on Queens Boulevard in Kew Gardens. With a classic sense of pessimism, he renamed it Poor Nick's.

LEAD: For 14 long and increasingly difficult years, Nelson Martinez, a 51-year-old real estate agent from suburban Los Angeles, has suffered from Parkinson's disease. But when he awoke from anesthesia in a hospital room here on Friday at dusk, he felt, he said to his wife amid tears of joy, ''as if I have been halfway dead and now have come back to life.