TIMOLOL
TISSUE-TYPING
T
timolol A
beta-blocker drug
used to treat
hypertension
and
angina pectoris.
Timolol
may also be given after a
myocardial in-
farction
. It is used as eye-drops to treat
glaucoma.
Possible side effects, such as
cold hands and feet, are typical of other
beta-blockers. Eye-drops may cause irri-
tation, blurred vision, and headache.
tinea Any of a group of common
fungal
infections
of the skin, hair, or nails. Most
are caused by fungi called dermato-
phytes. The infections may be acquired
from another person, an animal, soil,
the floors of showers, or from house-
hold objects, such as chairs or carpets.
The most common type of tinea infec-
tion is tinea pedis
(athlete's foot).
Tinea
corporis causes itchy, usually circular,
patches on the body. Tinea cruris (jock
itch) produces a reddened, itchy area
spreading from the genitals over the
inside of the thighs. Tinea capitis caus-
es round, itchy, patches of hair loss on
the scalp; it occurs mainly in children.
Ringworm of the nails (tinea unguium)
is often accompanied by scaling of the
soles or palms. The nails become thick
and turn white or yellow.
Most types are diagnosed by appear-
ance and by culturing the organisms in
a laboratory. Treatment is usually with
either topical or oral
antifungal drugs.
tingling See
pins-and-needles.
tinidazole An
antibacterial
drug that is
particularly useful in treating
anaerobic
infections. It is also used, together with
other drugs, to eradicate
Helicobacter
PYLORI
infection. Side effects may include
nausea, vomiting, gastrointestinal dis-
turbances, headache, and dizziness.
tinnitus A ringing, buzzing, whistling,
hissing, or other noise heard in the ear
or ears in the absence of a noise in the
environment. Tinnitus is almost always
associated with hearing loss, particularly
that due to
presbyacusis
and exposure
to loud noise. It can also occur as a
symptom of ear disorders such as
laby-
rinthitis, Meniere's disease, otitis media,
otosclerosis, ototoxicity,
and blockage of
the ear canal with earwax. It may also be
caused by certain drugs, such as
aspirin
or
quinine,
or may follow a
head injury.
Any underlying disorder is treated if
possible. Many sufferers make use of
a radio, television, cassette player, or
headphones to block out the noise in
their ears. A tinnitus masker, a hearing-
aid type device that plays white noise (a
random mixture of sounds at a wide
range of frequencies), may be effective.
tinzaparin A type of low molecular weight
heparin
that may be injected once daily
in the treatment of deep vein thrombo-
sis (see
thrombosis, deep
vein).
tiredness A common complaint that is
usually the result of overwork or poor
quality, or insufficient sleep. Persistent
tiredness may be caused by a number of
conditions, including
depression
,
anxi-
ety,
anaemia,
and
diabetes.
tissue A collection of
cells
specialized to
perform a particular function.
tissue fluid The watery liquid present
in the tiny gaps between body cells,
also known as interstitial fluid.
tissue-plasminogen activator A sub-
stance produced by body tissues that
prevents abnormal
blood clotting.
Also
called TPA, it is produced by the inner
lining of blood vessels. TPA can be pre-
pared artificially for use as a
thrombolytic
drug
, which is called alteplase. This is
used in the treatment of
myocardial
infarction
, severe
angina pectoris
, and
arterial
embolism
, including
pulmonary
embolism.
Possible side effects include
bleeding or the formation of a
haema-
toma
at the injection site and an allergic
reaction. (See also
fibrinolysis.)
tissue-typing The classification of cer-
tain characteristics of the
tissues
of
prospective organ donors and recipients
(see
transplant surgery
). This minimizes
the risk of rejection of a donor organ by
the recipient's
immune system.
A person's tissue type is classified in
terms of their
histocompatibility anti-
gens
, the most important of which are
the human leukocyte antigens (HLAs),
on the surface of cells. A person's set of
HLAs is inherited and unique (except
for identical twins, who have the same
set). Nevertheless, close relatives often
have closely matching HLA types. A
person's tissue-type is established by
laboratory tests on cells from a blood
sample. In one method, an antiserum
containing
antibodies
to a particular
HLA is added to the test specimen. If
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