Month: January 2021
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Yang
One of the two opposing forces in eastern philosophy associated with the earth, heat, brightness, activity, and masculinity.
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Xyletol
A sugar alcohol. made from birch trees, with sweetness equal to that of sucrose and caloric values the same as glucose. No longer used in the United States.
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X-linked gene
A gene known to be located on the X chromosome. A gene on the X chromosome for which there is no corresponding gene on the Y chromosome. X-linked genes (e.g., the gene for red-green color blindness) are expressed but in males even these genes are recessive because there is no corresponding gene to dominate them.…
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Xiphoid
The smallest and most dependent part of the breast bone.
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Xerosis
An abnormal dryness, as in conjunctiva or skin. Extreme dryness of skin or mucous membrane. Abnormal dryness of the conjunctiva, the skin, or the mucous membranes. Xerosis affecting the conjunctiva is due not to decreased production of tears but to changes in the membrane itself, which becomes thickened and gray in the area exposed when…
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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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Wry neck
Torticollis. A condition in which the head is twisted to one side. It may be caused by the contraction of a scar, such as that resulting from a burn, or by paralysis of some of the muscles; as a result of injury at birth; or trauma to the area later in life. Treatment is by…