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In 1864, the first barbiturate (barbituric acid) was synthesized.
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
Looking at the sun may not only cause headache and distort your vision temporarily, but it can also cause permanent eye damage. Any exposure to sunlight adds to the cumulative effects of ultraviolet (UV) radiation on your eyes. UV exposure has been linked to eye disorders such as macular degeneration, solar retinitis, and corneal dystrophies.
IgA antibodies protect body surfaces exposed to outside foreign substances. IgG antibodies are found in all body fluids. IgM antibodies are the first type of antibody made in response to an infection. IgE antibody levels are often high in people with allergies. IgD antibodies are found in tissues lining the abdomen and chest.
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.
![Urinalysis. During a simple urinalysis, a stick with colored blocks is dipped into a urine specimen.](https://biology-forums.com/gallery/47/medium_14755_26_10_12_5_21_07_96732306.jpeg)
![The “Big Four” world leaders meet at the Hotel Crillon in Paris, 1919. From left to right (front row](https://biology-forums.com/gallery/47/medium_4_23_06_16_8_41_01_236271811.jpeg)