Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «X»:
X (drug caution code)
X (drug caution code): Abbreviation on a medication that indicates SOS -- that the medication contains a substance such as acetaminophen that could cause problems -- consult your pharmacist.
While not a part of the historical heritage of ancient prescription abbreviations, drug caution codes provide...
X (in genetics)
X (in genetics): Although the letter X can be used as a
ways (such as with X-rays, the X-axis of a graph, etc.), "the X
" in genetics and medicine today usually
refers to the X chromosome.
The X is the sex chromosome that is found twice in
chromosomally normal femal...
X chromosome: A sex chromosome found in both females and males. Normal females usually have two X chromosomes. Normal males usually have one X along with a Y chromosome. The complete chromosome complement consisting of 46 chromosomes is conventionally
written as 46,XX for females and 46,XY for ...
X chromosome inactivation
X chromosome inactivation: See: X inactivation....
X inactivation: The phenomenon in a female by which one X chromosome (either the maternally or paternally derived X) is randomly (by chance) inactivated in an early embryonic cell, with fixed inactivation of that same X in all cells descended from that cell. The change that occurs with X inactivatio...
X, factor: A coagulation factor, a substance in blood essential to the normal clotting process. Production of factor X takes place in the liver and requires vitamin K. The gene for factor X is located on chromosome 13 and is in band 13q34.
The "X" in factor X is the Roman numeral "ten." (All number...
X-linked: On the X chromosome. "Linked" in
genetics does not mean merely associated. An X-linked gene travels with the X chromosome
and therefore is part of the X chromosome. ...
X-linked juvenile retinoschisis
X-linked juvenile retinoschisis: See: Juvenile retinoschisis....
X-linked retinoschisis: See: Juvenile retinoschisis....
X-ray: 1. High-energy radiation with waves shorter than those of visible light. X-rays possess the properties of penetrating most substances (to varying extents), of acting on a photographic film or plate (permitting radiography), and of causing a fluorescent screen to give off light (permitting flu...
X-ray crystallography: The use of X-rays of known wavelength to learn the structure of any crystalline material. Put otherwise, X-ray crystallography is a technology by which the locations of atoms in any crystal can be precisely mapped by looking at the image of the crystal under an X-ray beam.
X-ray, AP: An X-ray picture in which the beams pass from front-to-back
(anteroposterior). An AP film is as opposed to a PA (posteroanterior) film in which the
rays pass through the body from back-to-front....
X-ray, lateral: An X-ray picture taken from the side....
X-ray, PA: An X-ray picture in which the beams pass from back-to-front
(posteroanterior). By contrast an AP (anteroposterior) film is one in which the rays pass
through the body from front-to-back....
X-rays during pregnancy
X-rays during pregnancy: See: Prenatal radiation exposure....