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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.
ACTH levels are normally highest in the early morning (between 6 and 8 A.M.) and lowest in the evening (between 6 and 11 P.M.). Therefore, a doctor who suspects abnormal levels looks for low ACTH in the morning and high ACTH in the evening.
Approximately 500,000 babies are born each year in the United States to teenage mothers.
Elderly adults are living longer, and causes of death are shifting. At the same time, autopsy rates are at or near their lowest in history.
The Babylonians wrote numbers in a system that used 60 as the base value rather than the number 10. They did not have a symbol for "zero."