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After a vasectomy, it takes about 12 ejaculations to clear out sperm that were already beyond the blocked area.
A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.
In 1864, the first barbiturate (barbituric acid) was synthesized.
Many of the drugs used by neuroscientists are derived from toxic plants and venomous animals (such as snakes, spiders, snails, and puffer fish).
Long-term mental and physical effects from substance abuse include: paranoia, psychosis, immune deficiencies, and organ damage.