Webster's New World Medical Dictionary

Entoderm
See 
endoderm.
enucleation
The surgical removal of an eye.
Enucleation is done under drastic circumstances
such as to remove a malignant tumor in the eye or
to relieve intolerable pain in a blind eye. Following
enucleation, an artificial eye (ocular prosthesis) is
implanted as a cosmetic substitute for the real eye.
enuresis
Involuntary urination, which may be
caused by a variety of factors, including disorders of
the kidneys, bladder, or ureter, and poor control of
the muscles that control release of urine. Enuresis is
also occasionally associated with neurological dis-
orders, such as Tourette syndrome, particularly in
children. Nighttime (nocturnal) enuresis may be
related to any of the above, or it may be a symptom
of a sleep disorder. Palliative treatment options
include ensuring regularly scheduled toileting,
increasing awareness of the need to urinate, per-
forming exercises intended to strengthen the mus-
cles that control release of urine, using pads or
diapers to prevent embarrassing and uncomfortable
wetness, and in some cases using special devices
that alert the patient to the initial signs of wetness.
Treatment of enuresis usually involves treatment of
the underlying disorder. Cognitive behavioral ther-
apy or behavior modification techniques sometimes
also proves helpful. Also known as urinary inconti-
nence. See also 
bedwetting; Kegel exercises.
environmental tobacco smoke
See 
second-
hand smoke.
enzootic
Endemic in animals. An enzootic dis-
ease is constantly present in an animal population,
but usually only affects a small number of animals at
any one time.
enzyme
A protein or protein-based molecule that
speeds up a chemical reaction in a living organism.
An enzyme acts as a catalyst for specific chemical
reactions, converting a specific set of reactants
(substrates) into specific products. Without
enzymes, life as we know it would not exist. Errors
in the design of enzymes are responsible for numer-
ous diseases. See also 
enzyme defect.
enzyme defect
A disorder resulting from a defi-
ciency (or functional abnormality) of an enzyme.
For example, newborns are routinely screened for
certain enzyme defects, such as phenylketonuria
(PKU) and galactosemia.