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When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
The first oncogene was discovered in 1970 and was termed SRC (pronounced "SARK").
The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.
Over time, chronic hepatitis B virus and hepatitis C virus infections can progress to advanced liver disease, liver failure, and hepatocellular carcinoma. Unlike other forms, more than 80% of hepatitis C infections become chronic and lead to liver disease. When combined with hepatitis B, hepatitis C now accounts for 75% percent of all cases of liver disease around the world. Liver failure caused by hepatitis C is now leading cause of liver transplants in the United States.
The Romans did not use numerals to indicate fractions but instead used words to indicate parts of a whole.