Dr. John C. Lungren, 83, friend and personal physician of Richard M. Nixon's who diagnosed the former president's life-threatening blood clot. Lungren, also the father of former congressman and California Atty. Gen. Dan Lungren, was on the staff of Long Beach Memorial Medical Center for four decades and was its chief of staff from 1968 to 1971. The doctor also taught at UCLA and served on the California Medical Board. He was a specialist in internal medicine and cardiology and in 1977 underwent heart bypass surgery. A longtime friend of Nixon, Lungren worked on the Republican's various campaigns in the 1950s, 1960s and 1970s. Mostly, he once told The Times, he spent his days in the Nixon campaign entourage "taking care of reporters' colds and headaches." In 1969, then-President Nixon named Lungren his medical consultant. Shortly after Nixon's historic resignation in 1974, Lungren diagnosed a blood clot that had formed in the former chief executive's leg, passed through his heart and damaged his lung. Another doctor performed emergency surgery. Lungren continued to treat Nixon for phlebitis and give Nixon annual physical exams until Nixon moved to New York in 1980. Born in Sioux City, Iowa, Lungren was educated at the Universities of Notre Dame and Pennsylvania. He was an Army surgeon during World War II, was involved in the 1944 invasion of Normandy and earned four Battle Stars and a Purple Heart. On Monday in Long Beach of heart failure.