Richard A. Davis, 95, a neurosurgeon, medical educator, and researcher who was the brother of former first lady Nancy Reagan, died Friday, May 7, of congestive heart failure at his home in Villanova.

As Dr. Davis wrote in notes he penned for his obituary, he demanded much of himself and others in what he called “the University hospital trinity — superb patient care, devotion to teaching and excellence in neuroscience research.”

To Dr. Davis, his life in medical science was much more than a career.

“It was a calling,” said his daughter, Anne Peterson.

“His being a doctor was everything to him,” she said. “He went into the hospital seven days a week, holidays, to see his patients.”

Dr. Davis knew from boyhood growing up in Chicago that he wanted to be a physician. His early inspiration and supporter was his father, the pioneering neurosurgeon Loyal Davis. Raised by his father and mother Edith, Dr. Davis had a close relationship with his sister, Nancy, who would go on to marry Ronald Reagan.

A graduate of the Latin School of Chicago, Dr. Davis earned a bachelor’s degree in biology from Princeton University and graduated from Northwestern University Medical School.

He was later appointed a Kanaval fellow during his six-year residency in neurosurgery at the Northwestern University Medical Center, under the direction of his father. During his training, he also became junior assistant to the distinguished neurologist Arnold Carmichael at London’s National Hospital.

Dr. Davis’ 30-year career in medicine was centered in Philadelphia. He worked as a neurosurgeon at the Hospital of the University of Pennsylvania. He taught the principles of neurosurgery to medical students and residents at the University of Pennsylvania’s medical school, where he discouraged cold language like referring to patients as “cases” and urged compassion. He also conducted his own research and published more than 50 papers in various medical and scientific journals.

It was at the Hospital of the University of Pennsylvania that Dr. Davis met his wife, Patricia. She was head nurse of the hospital’s new intensive care unit, one of the first in the country, when they met in 1959. They were wed less than a year later. When Mrs. Davis died in February, the couple had been married for 60 years.

Dr. Davis and his wife had a close relationship with his sister and President Reagan.

They visited the White House often during the Reagan years. Their families got together in Washington at Christmastime and for the Fourth of July. The Davises attended both presidential inaugurations. And Dr. Davis and President Reagan enjoyed a great rapport.

“They were very, very close. My dad thought the world of him as a human being,” Peterson said. “They just had a great friendship. My dad was serious, and the president had a great sense of humor, so it was a great match. And my dad loved his sister, so they loved the same woman in different ways.”

Dr. Davis had a lifelong interest in the history of warfare and had served in the Navy during World World II and the Korean War. He became fluent in French in the 1980s and visited Normandy for commemorations of D-Day. In 1999, he self-published Yours, D3, a novel about a young parachute officer who grapples with issues of honor and leadership during World War II.

He also played golf and was a member of the Merion Golf Club. But even with golf,, his daughter said, he was still the professional, always a doctor, to the last detail.

“He was a true gentleman,” she said. “He would go to play golf, and I would say, `Dad, why are you in your suit? Why do you have to go in your suit, and change, and then shower?’ He looked at me and said, ‘Do you think someone wants to see the man who is going to operate on their brain with dirty hands?’ It was everywhere with him, all the time.”

In addition to his daughter, Dr. Davis is survived by son Geoffrey, three grandsons, and other relatives.

A private service will be held at a later time.

Donations in Dr. Davis’ memory may be made to the Latin School of Chicago, 69 W. North Blvd. Chicago, Ill. 60610.