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More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
Urine turns bright yellow if larger than normal amounts of certain substances are consumed; one of these substances is asparagus.
According to the CDC, approximately 31.7% of the U.S. population has high low-density lipoprotein (LDL) or "bad cholesterol" levels.
Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.