IRVING, Texas (AP) _ Melvin E. Bradford, an outspoken conservative who served as an adviser to Republican Patrick Buchanan's presidential campaign last year, died Wednesday at the age of 58.

The cause of death was not disclosed in a statement issued by the University of Dallas, where Bradford was an English professor.

President Reagan once picked Bradford to head the National Endowment for the Humanities, but his ultra-conservative views prompted the White House to seek another candidate.

Bradford once said that scholarly research proved Abraham Lincoln was a racist who used the Civil War as a tool to advance his political career. Cyril Collard

PARIS (AP) - Cyril Collard, a writer who made a highly acclaimed acting and directing debut in his film about coping with AIDS, died Friday of complications from the disease. He was 35.

Collard was one of the first French artists to make his fight with AIDS public. His death came four days before Monday's Cesar awards ceremony, where his film ''Savage Nights'' is up for seven Cesars, the French equivalent of the Oscars.

The movie has become a cult film in France, with its portrayal of the pain of confronting and coping with acquired immune deficiency syndrome. Collard directed the film and took on the starring role after it was refused by numerous actors. Robert de Liban

STANFORD, Calif. (AP) - Robert de Liban, an engineer on the Manhattan Project and a pioneer in developing automated guidance systems, died Sunday of complications following surgery. He was 74.

De Liban spent most of the war at Oak Ridge, Tenn., working on the project that led to the atomic bomb.

After the war, he co-founded Barrett Electronics Corp., a company that specialized in automated guidance systems for military and civilian enterprises. He was president of the western division of the company, which was sold in the 1980s. Kenneth Dole

RUSSELL, Kan. (AP) - Kenneth Dole, an oil lease broker and brother of U.S. Sen. Bob Dole, R-Kan., died Friday of cancer. He was 68. Jose F. Duval

CULVER CITY, Calif. (AP) - Jose F. Duval, the actor and singer perhaps best known as the original coffee planter Juan Valdez in television commercials for Colombian coffee, died Feb. 27 at the age of 72.

A native of Havana, Duval came to the United States when he was 20. He appeared in a production of ''Die Fledermaus'' at New York's Metropolitan Opera before venturing into musical theater and movies.

His musical credits include ''The King and I,'' ''Kismet'' and ''South Pacific.'' His film credits include ''The Cardinal'' and ''The Mambo Kings.'' George J. Keegan

BETHESDA, Md. (AP) - Maj. Gen. George J. Keegan Jr., a former intelligence officer who often warned that the United States was underestimating Soviet military might, died Wednesday at Bethesda Naval Hospital after suffering a stroke in January. He was 72.

A much-decorated World War II combat pilot, Keegan retired in 1977 after five years as assistant chief of staff for intelligence at Air Force headquarters at the Pentagon.

He flew 56 combat missions during World War II and served in Vietnam in the late 1960s. Izaak M. Kolthoff

ST. PAUL, Minn. (AP) - Izaak M. Kolthoff, a chemist whose research on synthetic rubber helped the Allied war effort during World War II, died Thursday. He was 99.

Kolthoff developed a process for making synthetic rubber at low temperatures, making large-scale production easier at a time when the war had cut off supplies of natural rubber.

In the 1950s he was an outspoken critic of Sen. Joseph McCarthy's anti- Communist purges, and in 1961 he launched a campaign of scientists opposed to nuclear weapons testing.

Kolthoff retired in 1962 but continued his research until recent years. He published nine books, including a widely used textbook of analytic chemistry, and more than 900 research papers. Charles Kueper

CAHOKIA, Ill. (AP) - Charles Kueper, a truck driver who lost a lawsuit against R.J. Reynolds Tobacco Co. in which he blamed his lung cancer on the company's cigarettes, died Friday of lung cancer at age 51.

Kueper claimed Reynolds and the Tobacco Institute conspired to use deceptive advertising to conceal the dangers of smoking. A St. Clair County jury ruled against him in January after a 10-week trial.

The trial sought damages in the tens of millions of dollars. Michel Riquet

PARIS (AP) - Jesuit priest Michel Riquet, one of France's foremost Roman Catholic authors who defied the Nazis during World War II and campaigned against racism, died Friday at the age of 94, his publisher announced.

Riquet became a Resistance fighter during the Nazi occupation of France in World War II, openly defying the policies of the collaborationist Vichy regime.

He helped more than 500 Allied pilots escape from France and was arrested by the Nazi Gestapo in January 1944.

He was deported to the Mathausen and Dachau concentration camps, and was freed by Allied soldiers in May 1945.

He is best known as the author of a series of spiritual ''how to'' books titled ''The Christian In the Face of ... Life, Ruin, Power, Atheism, Money.''