NEW YORK (AP) -- A 450-year-old piece of Charles V's pinkie lends support to the theory that it was gout that led one of the most powerful rulers of all time to abdicate, Spanish researchers report.

Holy Roman Emperor Charles V, whose empire stretched across Europe and included Spanish America, was diagnosed with gout by his doctors in early adulthood. By the end of his reign in 1556, he was a crippled man who could barely walk at times or ride a horse, said Dr. Pedro Luis Fernandez, a pathologist at the University of Barcelona.

"His physical suffering influenced decisions that affected the future of many countries," Fernandez and his colleagues reported in Thursday's New England Journal of Medicine.

To confirm the diagnosis of gout, a form of arthritis, the scientists did laboratory tests on a mummified piece of Charles V's little finger.

Fernandez said the fingertip was taken from his corpse at some point and later returned. It is kept in a red velvet box at the Royal Monastery of San Lorenzo de El Escorial, outside Madrid, where Charles V, who was also king of Spain, is buried.

The analysis revealed deposits of needle-shaped crystals of uric acid that had eroded tissue and bone -- a sure sign of gout. Such crystals are caused by a buildup of uric acid and result in pain and swelling of the joints, often the big toe.

Gout has long been associated with rich diets and alcohol. According to the researchers, Charles V had a big appetite, especially for meat, and drank large amounts of beer and wine. He died in 1558, probably of malaria.

The researchers note that some scholars think Charles V decided to abdicate after a gout attack in 1552 forced him to postpone an attempt to recapture the French city of Metz, where he was later defeated.

Dr. Howard Markel, director of the University of Michigan's Center for the History of Medicine, said lab tests on preserved body parts are providing valuable information.

"What used to be almost the doctors' equivalent of a parlor game -- Did (U.S. President Abraham) Lincoln have Marfan's disease? Or did Nero have lead poisoning? -- has actually become a rather unique tool in the exploration of the history of medicine and the history of disease," Markel said. "I think this is a perfect example of that."

2006 seasonal flu vaccine formula approved

WASHINGTON (AP) -- Vaccines that protect against three strains of seasonal influenza considered most likely to strike the northern hemisphere this winter have received federal approval.

Many nut-allergic kids can't spot the culprits

NEW YORK (Reuters) -- More than one in four children with nut allergies can't identify the nut that they are allergic to, a new study shows.

Wild Blue

Growing up in upstate New York, I remember eating blueberries the size of marbles. But those were cultivated berries -- not the tiny wild ones that are in season right now, as I discovered last year when I visited the wild blueberry fields in Maine. These petite gems don't grow on big bushes like the cultivated ones, but on small plants that barely reach my knees.

Body-image disorder brings higher suicide risk

NEW YORK (Reuters) -- People with "body dysmorphic disorder" are 45 times more likely to commit suicide than people in the general population, a new study shows.

Scientists take step toward obesity vaccine

NEW YORK (Reuters) -- In what could become a new weapon in the battle of the bulge, scientists on Monday reported initial success with an experimental vaccine for obesity.