Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «E»:
Exomphalos-macroglossia-gigantism syndrome: See: Beckwith-Wiedemann syndrome....
Exon: The region of a gene that contains the code for producing protein. Each exon codes for a specific portion of the complete protein. Exons are separated by introns, long regions of DNA that have no apparent function.
Exons are also called coding DNA....
Exonuclease: An enzyme that cleaves
nucleotide bases sequentially from the free ends of a nucleic acid (DNA or RNA)....
Exopeptidase: An enzyme that catalyzes the cleavage of the terminal (last) or next-to-last peptide bond from a polypeptide or protein, releasing a single amino acid or dipeptide. By contrast, an endopeptidase catalyzes the cleavage of then internal peptide bonds within a polypeptide or protein....
Exophthalmos: Protruding eyeball. A common
finding in hyperthyroidism (too much thyroid hormone) of Graves' disease....
Exotropia: Divergent gaze. Also called external
strabismus or, pejoratively, wall-eyed (like a walleyed pike). ...
Expectorant: A medication that helps bring up mucus and other material from the lungs, bronchi, and trachea. An example of as expectorant is guaifenesin which promotes drainage of mucus from the lungs by thinning the mucus and also lubricates the irritated respiratory tract. Sometimes the term "exp...
Expectoration: A big polysyllabic word for sputum or the act of bringing up and spitting out sputum. From the Latin expectorare, to expel from the chest, from ex-, out of + pectus, chest....
Expiration date: The date for a drug estimated for its shelf life with proper storage in sealed containers away from harmful and variable factors like heat and humidity.
The expiration date of a medicine is based on data, called accelerated stability data, from testing by the manufacturer, that sho...
Explant: 1. The original meaning: to transfer tissue from the body and place it in a culture medium for growth; and the tissue that is transferred.
2. To remove a device that
had been implanted. "It took about three hours to 'explant' Megan's pump
(ventricular assist device)...." (New York Times, ...
Explicit memory: Memory in which there is a need for conscious recollection in order to recall something. By contrast, in implicit memory there is a lack of conscious awareness in the act of recollection.
Implicit memory may survive largely unimpaired at the same time as a person's powers of explic...
Expressed sequence tag (EST)
Expressed sequence tag (EST): A unique stretch of DNA within a coding region of a gene that is useful for identifying full-length genes and serves as a landmark for mapping. An EST is a sequence tagged site (STS) derived from cDNA.
An STS is a short segment of DNA which occurs but once in the genom...
Expression, gene: See: Gene expression....
Expressivity: The consistency of a genetic disease.
For example, Marfan disease shows variable expressivity. Some persons with Marfan's merely
have long fingers and toes while others have the full-blown disease with dislocation of
the lens and dissecting aneurysm of the aorta. ...
Expulsion, stage of
Expulsion, stage of: The part of labor from the full dilatation of the
cervix until the baby is completely out of the birth canal. The second stage of labor....