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For about 100 years, scientists thought that peptic ulcers were caused by stress, spicy food, and alcohol. Later, researchers added stomach acid to the list of causes and began treating ulcers with antacids. Now it is known that peptic ulcers are predominantly caused by Helicobacter pylori, a spiral-shaped bacterium that normally exist in the stomach.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
The first oncogene was discovered in 1970 and was termed SRC (pronounced "SARK").
Of the estimated 2 million heroin users in the United States, 600,000–800,000 are considered hardcore addicts. Heroin addiction is considered to be one of the hardest addictions to recover from.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.