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Cocaine was isolated in 1860 and first used as a local anesthetic in 1884. Its first clinical use was by Sigmund Freud to wean a patient from morphine addiction. The fictional character Sherlock Holmes was supposed to be addicted to cocaine by injection.
Intradermal injections are somewhat difficult to correctly administer because the skin layers are so thin that it is easy to accidentally punch through to the deeper subcutaneous layer.
The Centers for Disease Control and Prevention (CDC) was originally known as the Communicable Disease Center, which was formed to fight malaria. It was originally headquartered in Atlanta, Georgia, since the Southern states faced the worst threat from malaria.
Multiple experimental evidences have confirmed that at the molecular level, cancer is caused by lesions in cellular DNA.
During the twentieth century, a variant of the metric system was used in Russia and France in which the base unit of mass was the tonne. Instead of kilograms, this system used millitonnes (mt).