I
ASCARIASIS
(kneecap), are now usually performed
arthroscopically.
Arthroscopic
surgery
substantially reduces the amount
of
recovery time required.
Arthrotec
The brand name of an
antirheumatic drug
containing
diclofenac
and
misoprostol.
articulation
The junction point of two or more
bones (see
joint).
artificial feeding
See
feeding, artificial.
artificial heart
See
heart, artificial.
artificial insemination
A form of assisted conception in which
semen is introduced artificially into the
uterus, instead of by sexual intercourse,
with the aim of inducing conception
and pregnancy.
TYPES
There are two types of artificial insemi-
nation: AIH, artificial insemination with
the semen of the woman’s male partner;
and AID, insemination with a donor’s
sperm. AIH is usually used for couples
who are unable to have intercourse, or
if the man has a low sperm count or a
low volume of ejaculate. It is also used
when a man’s semen has been stored
prior to his having treatment (such as
chemotherapy) that has made him sterile.
AID is available to couples if the man is
infertile or a carrier of a genetic disease.
It may also be used by a woman who
wants children but has no male partner.
HOW IT IS DONE
Artificial insemination is carried out at
centres that are specially staffed and
equipped to
obtain,
test,
and store
semen, to carry out the insemination,
and to give counselling before and after
the
procedure.
Semen
donors
are
screened for a wide variety of physical
and mental disorders.
Insemination is performed by inject-
ing
a
sample
of
semen
into
the
woman’s cervix using a small syringe.
The procedure is timed to coincide
with her
natural ovulation (the devel-
opment and release of an egg from the
ovary), or it may be combined with
treatment to stimulate ovulation.
artificial kidney
The common name for the machine
used in
dialysis.
artificial limb
See
prosthesis.
artificial respiration
See
rescue breathing.
artificial rupture of membranes
See
amniotomy.
artificial saliva
A preparation used to relieve a persis-
tently dry mouth, which may be a side
effect of certain drugs or
radiotherapy
or
may be due to
Sjogren’s syndrome
(an
autoimmune disorder in which the im-
mune system attacks the body’s own
tissues). Artificial saliva, as a spray, gel,
or pastilles, is formulated to resemble
natural saliva as closely as possible.
artificial sweeteners
Synthetic substitutes for sugar that are
used by people on slimming diets and
by the food industry.
Saccharin and aspartame are often
recommended
for
use
in
calorie-
controlled diets. They are, however, of
questionable value because the
appetite
compensates for the lack of calories
from sugar, therefore other foods are
eaten to maintain the calorie intake.
artificial tears
Preparations that are used to supplem-
ent tear production in disorders, such as
keratoconjunctivitis sicca,
that cause dry
eye and to relieve irritation.
arytenoid
One of two pyramid-shaped cartilages
that form part of the
larynx
(voice-box).
asbestos-related diseases
A variety of diseases that are caused by
inhalation of asbestos fibres. Asbestos is
a fibrous mineral formerly used as a
heat- and fire-resistant insulating mat-
erial. There are three main types of
asbestos fibre: white, which is widely
used, blue, and brown. Blue and brown
are
the
most
dangerous
types
of
asbestos. The use of all types is now
carefully controlled.
TYPES
In asbestosis, widespread fine scarring
occurs in the lungs. The disease causes
breathlessness and a dry cough, eventu-
ally leading to severe disability and death.
Asbestosis develops mostly in industrial
workers who have been heavily exposed
to asbestos. The period from initial
exposure to development of the disease
Electron micrograph of asbestos fibre in lung
An inhaled asbestos fibre impales and kills a
macrophage (a scavenger cell that would normally
engulf and destroy foreign particles in the lungs).
is usually at least 20 years. Diagnosis is
by
chest X-ray.
Asbestosis increases the
risk of developing
lung cancer.
Mesothelioma
is a cancerous tumour
of the
pleura
(the membrane surround-
ing the lungs) or the
peritoneum
(the
membrane lining the abdominal cav-
ity). In the pleura, mesotheliomas cause
pain and breathlessness; in the peri-
toneum they cause enlargement of the
abdomen
and
intestinal
obstruction.
The condition cannot be treated and
usually leads to death within one or two
years. The average interval between ini-
tial exposure to asbestos and death is
between 20 and 3 0 years. Mesothe-
lioma affects people who have been
exposed to blue or brown asbestos.
Diffuse pleural thickening is a condi-
tion in which the outer and inner layers
of the pleura become thickened, and
excess fluid may accumulate in the cav-
ity between them. This combination
restricts the ability of the lungs to
expand, resulting in shortness of breath.
The condition may develop even after
short exposure to asbestos.
asbestosis
See
asbestos-related diseases
.
ascariasis
Infestation with the roundworm ASCARIS
LUMBRICOIDES, which lives in the small
intestine of its human host. Ascariasis is
common worldwide, especially in the
tropics. One or several worms may be
present, but symptoms usually only
occur with heavy infestation.
A
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