GTNThe abbreviation for glyceryl tri-
nitrate.
guar gumA gum extracted from the
cluster bean (CYAMOPSIS TETRAGONOLABA).
Guar gum is not digested in the body. It
is taken (as granules sprinkled on food
or dissolved in water) as an aid to con-
trolling the blood glucoselevel in people
with diabetes mellitusbecause it slows
absorption of glucose in the small in-
testine. Guar gum may cause flatulence,
nausea, and abdominal discomfort.
Guillain–Barré syndromeA rare con-
dition affecting the peripheral nerves
(see peripheral nervous system) that
causes weakness, usually in the limbs.
The cause is believed to be an allergic
reaction to an infection, usually viral;
the nerves are damaged by antibodies
produced by the body to eliminate the
infection. In most cases, the disease
develops 2 or 3 weeks after the onset of
infection. Weakness, often accompanied
by numbness and tingling, usually starts
in the legs and spreads to the arms. The
weakness may become progressively
worse, resulting in paralysis. The mus-
cles of the face and those controlling
speech, swallowing, and breathing may
also be affected.
Diagnosis of Guillain–Barré syndrome
is confirmed by electrical tests to mea-
sure how fast nerve impulses are being
conducted, or by a lumbar puncture.
Most people recover fully with only sup-
portivetreatment. However, in severe
cases, treatment with plasmapheresisor
immunoglobulinmay be given. Mechan-
ical ventilation may be needed to aid
breathing if the respiratory muscles and
diaphragmare severely affected. Some
people are left with permanent weak-
ness in affected areas and/or suffer from
further attacks of the disease.
guiltA painful feeling that arises from
the awareness of having broken a moral
code. Guilt is self-inflicted, unlike shame,
which depends on how other people
view the transgression. Some psycho-
analysts view guilt as a result of the
prohibitions of thesuperegoinstilled by
parental authority in early life. Others
see guilt as a conditioned response to
actions that in the past have led to pun-
ishment. Feeling guilty for no reason orfor an imagined crime is one of the
main symptoms of psychotic depression.
Guinea worm diseaseA tropical dis-
ease caused by a female parasitic worm
more than 1 m long. Infection is the
result of drinking water containing the
water flea cyclops, which harbours larvae
of the worm. The larvae pass through
the intestine and mature in body tissues.
After about a year, the adult female worm,
now pregnant, approachesthe skin sur-
face and creates an inflamed blister that
bursts, exposing the end of the worm.
Urticaria, nausea, and diarrhoea often
develop while the blister is forming. The
disease occurs in Africa, South America,
the Caribbean, Middle East, and India.
The traditional remedy is to wind the
worm from the skin on to a small stick.
Once the worm is out, the condition
usually clears up. The drugs tiabenda-
zoleand niridazole are given to reduce
inflammation, antibioticsare given to
control secondary infection, and the
patient is immunized against tetanus.
Gulf War syndromeA group of symp-
toms caused by exposure of people in
the armed forces to chemicals, includ-
ing insecticides, used during the Gulf
War in 1991. Gulf War syndrome may
also be due to side effects of vaccines
and drugs given to the armed forces to
prevent against possible attacks of
chemical and biological weapons.
gulletCommon name for the oesophagus.
gumThe soft tissue surrounding the teeth
that protects underlying structures and
keeps the teeth in position in the jaw.
Healthy gums are pink or brown and
firm. Careful oral hygienehelps prevent
gum disease. Gingivitismay occur if
plaqueis allowed to collect around the
base of the teeth. Untreated gingivitis
may lead to chronic periodontitis. Bleed-
ing gums are nearly always a symptom
of gingivitis; rarely, they are due to
leukaemiaor scurvy. Gingival hyperplasia
occurs most often as a side-effect of
treatment with phenytoin.
gumboilSee abscess, dental.
gummaA soft tumour that may develop
in the late stages of untreated syphilis.
These tumours are very uncommon in
developed countries.
gutA common name for the intestine.GTN GUTG