A metallic element that is used as nuclear fuel and is highly toxic and radioactive. Exposure to radiation from uranium can occur in various ways. The breakdown of uranium products creates radon daughters. These can attach to dust particles and, if workers inhale the dust, the particles lodge in their lungs, where they release high doses of radiation. This is believed to be why Navajo uranium miners face a risk of lung cancer that is 28 times normal.
A salt derived from uric acid. When the body cannot metabolize uric acid properly, urates can build up in body tissues or crystallize within the joints. See also gout, uric acid.
- Urban typhus of Malaya
Murine typhus, an acute infectious disease with fever, headache, and rash, all quite similar to, but milder than, epidemic typhus. It is caused by a related microorganism, Rickettsia typhi (R. mooseri), transmitted to humans by rat fleas (Xenopsylla cheopis). The animal reservoir includes rats, mice and other rodents. Murine typhus occurs sporadically worldwide but is […]
A nitrogen-containing substance normally cleared from the blood by the kidney into the urine. Diseases that compromise the function of the kidney often lead to increased blood levels of urea, as measured by the blood urea nitrogen (BUN) test. Urea is of major historical significance. It was the first organic chemical compound ever synthesized. The […]
- Urea breath test (UBT)
The urea breath test (UBT) is a procedure for diagnosing the presence of a bacterium, Helicobacter pylori (H. pylori) that causes inflammation, ulcers, and atrophy of the stomach. The test also may be used to demonstrate that H. pylori has been eliminated by treatment with antibiotics. The urea breath test is based on the ability […]
A bacterium that commonly infects the urogenital tract and can cause premature birth or spontaneous abortion. During delivery, ureaplasma can infect the newborn and cause meningitis, pneumonia, or septicemia. Ureaplasma is similar to mycoplasma. They are among the smallest free-living organisms known. Ureaplasma lacks several proteins standard in comparable organisms. Its low biosynthetic capacity means […]