I
munication and social skills). Special
educational support may be necessary,
often within mainstream education. Asp-
erger’s syndrome is a lifelong condition.
aspergillosis
An infection caused by inhalation of
spores of aspergillus, a fungus that grows
in decaying vegetation. Aspergillus is
harmless to healthy people but may
proliferate in the lungs of people with
tuberculosis.
It
can
also worsen the
symptoms of
asthma
and may produce
serious, even fatal, infection in people
with reduced immunity, such as those
taking
immunosuppressant drugs.
aspermia
See
azoospermia
.
asphyxia
The
medical
term
for
suffocation.
Asphyxia may be caused by the obstruc-
tion of a large airway, usually by a
foreign body (see
choking),
by insuffi-
cient oxygen in the surrounding air (as
occurs when, for example, a closed
plastic bag is put over the head), or by
poisoning with a gas, such as carbon
monoxide,
that
interferes
with
the
uptake of oxygen into the blood.
The person initially breathes more
rapidly and strongly to try to overcome
the lack of oxygen in the blood. There
is also an increase in heart rate and
blood pressure.
First-aid treatment is by clearing the
airway of obstruction followed by
res-
cue breathing.
Untreated asphyxia leads
to death within a few minutes.
aspiration
The withdrawal of fluid or cells from
the body by suction. The term also
refers to the act of accidentally inhaling
a foreign body, usually food or drink. If
consciousness is impaired, for example
by a head injury or excess alcohol
intake, aspiration of the stomach con-
tents is common.
Aspiration
biopsy
is the removal of
cells or fluid, using a needle attached to
a syringe, for examination. Aspiration
biopsy is commonly used to obtain cells
from a fluid-filled cavity (such as a
breast cyst).
The procedure is also used
to obtain cells from the bone marrow
(see
bone marrow biopsy),
or from inter-
nal organs, when a fine needle is guided
to the site of the biopsy by
CT scanning
or
ultrasound scanning.(See
also
aspir-
ation pneumonia.)
ASTHMA
aspiration pneumonia
A form of pneumonia that results from
accidental inhalation of vomit. Aspiration
pneumonia usually occurs in people
whose cough reflex is not functioning,
such as those who have drunk excessive
amounts of alcohol, taken certain illegal
drugs, or suffered a head injury.
aspirin
A nonopioid
analgesic drug
(painkiller)
that may be given in tablet or supposi-
tory form to treat disorders such as
headache, menstrual pain, and muscle
discomfort. Aspirin has an
anti-inflamma-
tory
action. It also reduces fever and is
included in some
cold remedies
.
In small doses, aspirin reduces the
stickiness of platelets (blood particles
involved in clotting). This has led to its
use in preventing
thrombosis
(abnormal
blood clots) in people at risk of devel-
oping
stroke
or
myocardial infarction
(heart attack) and as an initial treatment
of chest pain that may be due to myocar-
dial infarction. Aspirin may also reduce
the risk of
colon cancer
and slow the
progress of
dementia.
In children, aspirin can cause
Reye’s
syndrome,
a rare but serious brain and
liver disorder. For this reason, it should
not be given to children under the age
of 16 years, except on the advice of a
doctor.
Aspirin
may
cause
irritation
of the stomach lining, resulting in indi-
gestion or nausea. Prolonged use may
cause bleeding from the stomach due to
gastric erosion
(disruption of the stom-
ach lining) or
peptic ulcer.
Aspro
A brand name for
aspirin.
assay
The analysis or measurement of a sub-
stance to determine its presence or
effects. A qualitative assay determines
only whether or not a substance is
present, whereas a quantitative assay
determines the actual amount present.
Biological assays (known as bioassays)
measure the response of an animal or
organ to particular substances. Assays
can be used, for example, to assess
the effects of a drug or to measure hor-
mone levels.
(See also
immunoassay
;
radioimmunoassay
.)
assisted conception
Treatment for
infertility
involving tech-
niques that assist the fertilization and
implantation of eggs.
association area
One of a number of areas in the cortex
(outer layer) of the
brain
that are con-
cerned with higher levels of mental
activity. Association areas interpret infor-
mation received from sensory areas and
prompt appropriate responses, such as
voluntary movement.
associative aphasia
Also known as conductive aphasia, a
form of
aphasia
(loss of language skills,
including comprehension and/or speech
production) in which comprehension is
normal, and the affected individual can
write and speak, but he or she is unable
to repeat what has been heard and can-
not read aloud. Associative aphasia is
caused by damage to a localized area in
the brain, often as a result of a
stroke
.
astereognosis
The inability to recognize objects by
touch when they are placed in the
hand, even though there is no defect of
sensation in the fingers or difficulty in
holding
the
object. Astereognosis
is
either left- or right-sided; tactile recog-
nition is normal on the other side. If
both sides are affected, the condition is
called tactile
agnosia
.
Astereognosis and tactile agnosia are
caused by damage to parts of the
cere-
brum
(the main mass of the brain) that
are involved in recognition by touch.
The conditions may occur as a result of
a
stroke
or a
head injury.
asthenia
An outdated term for loss of strength
and energy (see
weakness).
asthenia, neurocirculatory
See
cardiac neurosis.
asthma
A lung disease in which there is inter-
mittent
narrowing
of
the
bronchi
(airways), causing shortness of breath,
wheezing, and a cough. The illness
often starts in childhood but can develop
at any age. At least one child in seven
suffers from asthma, and the number
affected has increased dramatically in
recent years. Childhood asthma may be
outgrown in about half of all cases.
During an asthma attack, the muscle
in the walls of the airways contracts,
causing narrowing. The lining of the
airways also becomes swollen and in-
flamed, producing excess mucus that
can block the smaller airways.
A
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