Category: X
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Xenon-washout blood flow test
A test of blood flow to the male genitals to diagnose erectile dysfunction.
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Xanthurenic acid
A metabolite of tryptophan is found in normal urine, but appears in increased amounts in cases of vitamin B6 deficiency. An acid, C10H7NO4, excreted in the urine of pyridoxine-deficient animals after they are fed tryptophan. Also called 4,8-dihydroxyquinaldic acid
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Xanthomas
A small yellow plaque in the skin due to a fat deposit. A yellow fatty mass, often on the eyelids and hands, found in people with a high level of cholesterol in the blood. Benign, fatty, yellowish plaque, nodule, or tumor in the subcutaneous layers of the skin, usually due to accumulation of cholesterol and…
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Xanthine
A nitrogenous extractive contained in muscles tissue, liver, spleen, pancreas, and other organs and in the urine, formed during the metabolism of nucleoproteins. It is acted upon by certain enzymes to form uric acid and is excreted in the urine. An intermediate product in the breakdown of nucleic acids to uric acid, found in blood,…
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Xeropthalmia
A disease caused by a deficiency of vitamin A and characterized by a thickening and inflammation of the outer layers of the eye and impaired eyesight.
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Xyster
Not wanting to waste any of a chicken or turkey, many cooks will scrape and pluck the remaining pieces of meat from a carcass before they throw the bones into the soup pot or trash can. Most often, the implement used to cut these scraps of meat from the bone is a simple kitchen knife,…
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Xenia
Xenia, in ancient Greece and Rome, were table delicacies graciously presented to a tired stranger upon his or her arrival in the host’s home. The word derives from the Greek word xenos, meaning stranger. In the Middle Ages, the custom of the xenia was co-opted by royalty who turned it from a free act of…
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Xanthan
Xanthan is a gummy substance produced by a bacterium that takes its full scientific name—xanthomonas, Greek for yellow one—from the colour of the mould it produces. Xanthan has two uses: in the food industry it is used to stabilize emulsions—that is, it stops certain beverages or ready-made sauces from separating into a thick part that…
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Xenotransplant
From the Greek word xenos, meaning “stranger.” Xenotransplant is the implantation of an organ or limb from one species to another organism in a different species. When performed in animals, “rejection” of the transplant by the recipient’s immune system is a common response.
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Xenogenesis
The (theoretical) production of offspring that are genetically different from, and genotypically unrelated to either of the parents of that offspring. The process of producing offspring that differ from the parents.