timololA beta-blocker drugused to treat
hypertensionand 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.
tineaAny of a group of common fungal
infectionsof 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.
tinglingSee pins-and-needles.
tinidazoleAn antibacterialdrug 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.
tinnitusA 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 presbyacusisand exposure
to loud noise. It can also occur as a
symptom of ear disorders such as laby-
rinthitis, Ménière’s disease, otitis media,
otosclerosis, ototoxicity, and blockage of
the ear canal with earwax. Itmay 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 ofa 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.
tinzaparinA type of low molecular weight
heparin that may be injected once daily
in the treatment of deep vein thrombo-
sis (see thrombosis, deep vein).
tirednessA common complaint that is
usually the result of overwork or poor
quality, or insufficient sleep. Persistent
tirednessmay be caused by a number of
conditions, including depression, anxi-
ety, anaemia,and diabetes.
tissueA collection of cellsspecialized to
perform a particular function.
tissue fluidThe watery liquid present
in the tiny gaps between body cells,
also known as interstitial fluid.
tissue-plasminogen activatorA 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-
tomaat the injection site and an allergic
reaction. (See also fibrinolysis.)
tissue-typingThe classification of cer-
tain characteristics of the tissuesof
prospective organ donors and recipients
(see transplant surgery). Thisminimizes
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 antibodiesto a particular
HLA is added to the test specimen. IfTIMOLOL TISSUE-TYPINGT