COCKAYNE’S SYNDROME
C
COCHLEAR IMPLANT
Sounds picked up by the microphone are converted
R e c e i v e r
into electronic signals by the sound processor and
relayed to the external transmitter, which sends
them through the skin to the receiver. The waves
then travel along the wire to the electrodes in the
cochlea, where sound is normally received.
V e s t i b u l o c o c h l e a r n e r v e
M i c r o p h o n e
T r a n s m itt e r
W ire f r o m
m i c r o p h o n e
t o p r o c e s s o r
E l e c t r o d e
T r a n s m it t e r
C o c h l e a
Cockayne’s syndrome
An autosomal recessive
genetic disorder
that causes premature aging and dete-
rioration of the nervous system. The
syndrome causes dwarfism (see
short
stature
)
and abnormally rapid aging
(see
progeria
) .
Affected
people
also
have very thin skin that is extremely
sensitive to the effects of sunlight. In
addition, there may be visual problems
due to degeneration of the retina (see
retinitis pigmentosa
)
or atrophy (wast-
ing away) of the
optic nerve
;
deafness
;
and
learning difficulties
.
The
age
at
w hich
symptoms
appear
and
the
course of the disease vary from one
individual to another.
There is no cure for the aging or the
neurological symptoms, but an affected
person can protect his or her skin from
sun damage by avoiding exposure to
ultraviolet light, or by applying a sun-
block to protect areas of exposed skin
when outdoors in sunlight.
co-codamol
A compound
analgesic drug
containing
paracetamol
and
codeine
.
codeine
An
opioid analgesic drug
derived from
the opium poppy plant. Codeine is use-
ful for m ild to moderate pain and may
be combined with other analgesics in
painkilling preparations. It is also used
as
a
cough remedy
and
as
an
anti-
diarrhoeal drug
.
It may cause dizziness and drowsiness,
especially if taken with alcohol. If used
for long periods, it may cause constipa-
tion and be habit-forming.
cod-liver oil
A pale yellow oil obtained from the
liver of fresh cod, w hich is a valuable
source of
vitamin A
and
vitamin D
.
co-dydramol
A compound
analgesic drug
(painkiller)
that contains
paracetamol
and dihydro-
codeine.
coeliac disease
A condition, sometimes called gluten-
sensitive enteropathy, that results from
hypersensitivity
to
gluten
,
a
protein
found in wheat, rye, and some other
cereals. Exposure to foods containing
gluten causes an abnormal immune
response in w hich the lining of the
small intestine is damaged. The condi-
tion leads to
malabsorption
and results
in vitamin and mineral deficiencies.
CAUSES AND SYMPTOMS
Coeliac disease tends to run in families,
and varies in severity. The disorder may
first appear during infancy, or may not
develop until adulthood.
In babies, symptoms usually develop
w ithin six months of the introduction
of gluten into the diet. The baby may
become listless and irritable, develop
vom iting and diarrhoea, and become
dehydrated and seriously ill. Babies
and children may also fail to grow or
to gain weight, and may suffer from
muscle wasting, especially around the
buttocks.
In
adults,
symptoms
that
include tiredness, breathlessness, abdo-
minal pain, diarrhoea, vomiting, and
swelling of the legs may develop over
several months. In addition, a chronic,
distinctive rash called
dermatitis herpeti-
formis
may occur.
Damage to the intestinal lining and
malabsorption cause weight loss and
result in faeces that are bulky and foul-
smelling. The
resulting
vitamin
and
mineral
deficiencies
can
result
in
anaemia
as well as skin problems. Some
affected people suffer damage to the in -
testinal
lining
but
never
develop
symptoms of the disease.
DIAGNOSIS AND TREATMENT
Diagnosis may be made by blood tests
but in most cases
jejunal biopsies
,
in
w hich tissue samples from the lining of
the jejunum (the central part of the
small intestine) are taken for examina-
tion, are also performed.
Coeliac disease is treated by a life-
long gluten-free diet, w hich can relieve
symptoms w ithin weeks of its intro-
duction. Specially manufactured foods,
such as gluten-free flour and pasta, are
available. W ithout such treatment, there
may be a long-term risk of cancers
developing in the small intestine.
coenzyme
A nonprotein chemical, occurring nat-
urally in the body, that plays a role in
assisting
the
proper
functioning
of
some types of
enzyme
(proteins that
regulate
chemical
reactions
in
the
body). (See also
NAD
. )
Coffin-Siris syndrome
An autosomal
genetic disorder
character-
ized by absence or underdevelopment
of the tips of the little finger and little
toe. Other features include
hirsutism
(excessive
hair),
hypotonia
(lack
of
muscle
tone)
and weak
joints,
and
learning difficulties
.
cognition
Mental processes by w hich knowledge
is acquired. Such cognitive processes
include
perception,
problem-solving,
and reasoning.
cognitive-behavioural therapy
A method of treating psychological dis-
orders such as
anxiety
and
depression
,
based on the idea that problems arise
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