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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.
Interferon was scarce and expensive until 1980, when the interferon gene was inserted into bacteria using recombinant DNA technology, allowing for mass cultivation and purification from bacterial cultures.
After a vasectomy, it takes about 12 ejaculations to clear out sperm that were already beyond the blocked area.
Amoebae are the simplest type of protozoans, and are characterized by a feeding and dividing trophozoite stage that moves by temporary extensions called pseudopodia or false feet.
To prove that stomach ulcers were caused by bacteria and not by stress, a researcher consumed an entire laboratory beaker full of bacterial culture. After this, he did indeed develop stomach ulcers, and won the Nobel Prize for his discovery.