GLYCOGEN STORAGE DISEASES
glue ear
Accumulation of fluid in the cavity of
the
middle ear
,
causing impaired hear-
ing. Persistent glue ear is most common
in children. It is often accompanied by
enlarged
adenoids
and frequently occurs
with viral respiratory tract infections,
such as the common
cold
.
It is usual for
both ears to be affected.
In glue ear, the lining of the middle
ear becomes overactive, producing large
amounts of a sticky fluid, and the
eusta-
chian tube
(w hich links the middle ear
to the back of the nose and throat)
becomes
blocked
so
that
the
fluid
cannot
drain away. The accumulated
fluid interferes with the movement of
the delicate bones of the middle ear.
Glue ear is sometimes first detected
by
hearing tests
.
Examination w ith an
otoscope
(viewing
instrument)
can
confirm the diagnosis.
M ild cases of the condition often
clear up without specific treatment. If
symptoms persist, the insertion of
grom-
mets
(small tubes) may be necessary,
w hich allows air into the middle ear
and encourages fluid to drain away.
Adenoidectomy
(removal of the aden-
oids) may also be required.
Effects of glue ear
In this condition, sticky fluid in the middle ear
prevents free movement of the eardrum and
ossicles, causing deafness.
glue-sniffing
See
solvent abuse
.
glutaraldehyde
A topical (applied to the skin) prepara-
tion for the treatment of
warts
,
especially
plantar warts
(verrucas). Glutaraldehyde
may cause a rash or irritation and may
stain the skin brown.
gluteal
A term meaning “relating to the but-
tocks” , as in the gluteal muscles.
gluten
A combination of gliadins and gluten-
ins (types of proteins) present in wheat,
rye, and barley. Mixed with water, flours
containing gluten become sticky and
trap air, thus forming dough. Sensitivity
to gluten causes
coeliac disease
.
gluten enteropathy
See
coeliac disease
.
gluten intolerance
See
coeliac disease
.
gluteus maximus
The large, powerful
muscle
in each of
the
buttocks
that
gives
them
their
rounded shape. The gluteus maximus is
responsible for moving the thigh side-
ways and backwards.
glycerol
A colourless, syrupy liquid that has a
sweet taste. Glycerol is an essential con-
stituent of
triglycerides
(simple fats) in
the body. It may also be prepared com-
mercially from
fats and oils
.
Glycerol is
added to moisturizing creams to help
prevent dryness and cracking of the
skin. It is also used in eardrops to help
soften earwax, and in
cough remedies
to
help soothe a dry, irritating cough. Fur-
thermore, glycerol is added to rectal
suppositories
;
it relieves
constipation
by
softening hard faeces.
glyceryl trinitrate
A
vasodilator drug
used for the treatment
and prevention of symptoms of
angina
pectoris
(chest pain due to inadequate
blood supply to the heart).
Sublingual
or
buccal
sprays and tablets are available for
rapid pain relief and slow-release tablets
or skin patches for sustained pain relief.
The drug is sometimes prescribed to
treat anal fissures but is not licenced
for this use. High doses may cause
headaches, flushing, and dizziness.
glycogen
The main form of
carbohydrate
stored in
the body. Glycogen is a polysaccharide,
consisting of chains of
glucose
mol-
ecules, and is found mainly in the liver
and in muscles.
W hen there is excess glucose in the
blood, it is converted to glycogen by
the action of
insulin
and
glucocorticoids
(a
class
of
corticosteroid
hormones
) .
W hen the blood glucose level is low,
glycogen is converted back to glucose
(regulated by
adrenaline
and
glucagon
)
and released into the bloodstream.
glycogen storage diseases
A group of rare
genetic disorders
charac-
terized by an absence or deficiency of
certain
enzymes
(proteins that act as
catalysts) responsible for the metabo-
lism of
glycogen
.
These enzyme defects
may lead to abnormal concentrations of
glycogen in the tissues, insufficient
glu-
cose
(a simple sugar) in the blood, or
the inability of the body to use glucose
as energy. Also known as glycogenoses
or GSDs, these diseases may affect the
liver, the muscles, or both.
G
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