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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.
Symptoms of kidney problems include a loss of appetite, back pain (which may be sudden and intense), chills, abdominal pain, fluid retention, nausea, the urge to urinate, vomiting, and fever.
More than one-third of adult Americans are obese. Diseases that kill the largest number of people annually, such as heart disease, cancer, diabetes, stroke, and hypertension, can be attributed to diet.
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).