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Pope Sylvester II tried to introduce Arabic numbers into Europe between the years 999 and 1003, but their use did not catch on for a few more centuries, and Roman numerals continued to be the primary number system.
Autoimmune diseases occur when the immune system destroys its own healthy tissues. When this occurs, white blood cells cannot distinguish between pathogens and normal cells.
Once thought to have neurofibromatosis, Joseph Merrick (also known as "the elephant man") is now, in retrospect, thought by clinical experts to have had Proteus syndrome. This endocrine disease causes continued and abnormal growth of the bones, muscles, skin, and so on and can become completely debilitating with severe deformities occurring anywhere on the body.
More than 150,000 Americans killed by cardiovascular disease are younger than the age of 65 years.
Human neurons are so small that they require a microscope in order to be seen. However, some neurons can be up to 3 feet long, such as those that extend from the spinal cord to the toes.