DIPHENHYDRAMINE
D
diphenhydramine
An
antihistamine drug
that is used to
treat allergic disorders such as
urticaria
(nettle rash) and allergic
rhinitis
(hay
fever). Diphenhydramine is also used
for the relief of temporary sleep distur-
bance, and is an ingredient in some
cough remedies
.
It can cause drowsiness,
dry mouth, and blurred vision.
diphenoxylate
An
antidiarrhoeal drug
that is chemically
related to the opioid
analgesic drugs
(painkillers). Diphenoxylate lessens the
contractions of the muscles in the walls
of the intestines, thereby reducing the
frequency of bowel movements.
diphtheria
A bacterial infection that causes a sore
throat, fever, and sometimes serious or
even fatal complications. Diphtheria is
caused by the bacillus C
orynebacterium
diphtheriae
. The disease is now rare in
developed countries as a result of mass
immunization
.
In the UK, the vaccine is
given at 2, 3, and 4 months, 3-5 years,
and 13-18 years of age.
SYMPTOMS
The infection may begin in the throat or
in the skin. In the throat, multiplication
of bacteria causes the formation of a
membrane that may cover the tonsils
and spread up over the palate or down
to the larynx (voicebox) and the trachea
(windpipe), causing
breathing difficulty
and a husky voice. Other symptoms
include enlarged
lymph nodes
in the
neck, an increased heart rate, and m ild
fever. If infection is confined to the skin,
the bacteria may produce a yellowish
lesion covered by a hard membrane.
Life-threatening symptoms occur only
in people who are not immune to the
disease. They are caused by a toxin that is
released by the bacteria and affects the
heart and nervous system. Occasionally, a
victim collapses and dies within a day of
developing throat symptoms. More often,
the victim is recovering from diphtheria
when
heart failure
or paralysis of the
throat or limbs develops. These com-
plications can occur up to seven weeks
after the onset of infection in the throat.
TREATMENT
Diphtheria is treated with antibiotics;
in addition, an antitoxin is given to
neutralize the bacterial toxin. If severe
breathing difficulties develop, a
tracheo-
stomy
(the surgical introduction of a
breathing tube into the w indpipe) may
also be necessary.
diplegia
Paralysis
affecting
both sides
of the
body (both legs and, to a lesser extent,
both arms). (See also
spastic diplegia
. )
diplopia
The
medical
term
that
is
used
to
describe
double vision
.
dipsomania
A form of
alcohol dependence
in w hich
periods of excessive drinking and crav-
ing for drink alternate with periods of
relative sobriety.
dipyridamole
A drug that reduces the stickiness of
platelets in the
blood
and thereby helps
to prevent the formation of abnormal
blood clots w ithin arteries. Dipyrida-
mole
may
be
used with
aspirin
or
warfarin
to prevent the formation of
blood clots following
stroke
or
transient
ischaemic attack
or in people who have
artificial heart valves.
Possible adverse effects may include
headache, flushing, and dizziness.
disability
A loss or impairment of normal func-
tioning or activity as the result of a
physical or mental impediment. (See
also
handicap
;
rehabilitation
. )
disaccharide
A
carbohydrate
comprising two linked
monosaccharide
units. Lactose, maltose,
and sucrose are all disaccharides.
discectomy
A procedure in w hich part or all of a
damaged intervertebral disc (see
disc,
intervertebral
)
is
surgically
removed.
Discectomy relieves the symptoms of
disc prolapse
(in w hich an intervertebral
disc ruptures and part of its pulpy core
protrudes)
by relieving the pressure
that the protruding tissue places on
nerves or nerve roots.
discharge
A visible emission of fluid from an ori-
fice or a break in the skin (such as a
wound or burst b o il). A discharge may
be a normal occurrence, as in some
types of
vaginal discharge
,
but it could
also
be
due
to
an
infection
or to
inflammation, as occurs, for example,
in
rhinitis
(inflammation of the lining
of the nasal passages),
urethritis
(infec-
tion of the urethra),
or in
proctitis
(infection of the rectum).
disciformis, keratitis
A form of
keratitis
(inflammation of the
cornea at the front of the eye) in w hich
a disc-like opacity forms in the corneal
tissue, usually as an
immune response
to
a viral infection.
disc, intervertebral
One of the flat, circular, platelike struc-
tures containing
cartilage
that line the
joints
between
adjacent
vertebrae
(bones) in the
spine
.
Each interverte-
bral disc is composed of a fibrous outer
layer and a soft, gelatinous core. The
discs act as shock absorbers to cushion
the vertebrae during movements of the
spine. W ith increasing age, interverte-
bral discs become less supple and more
susceptible to damage from injury; one
of the most common problems is
disc
prolapse
(“slipped” disc).
disclosing agents
Dyes that make the
plaque
deposits on
teeth more visible so that they can be
seen and removed.
discoid lupus erythematosus
A form of the chronic autoimmune
disorder
lupus erythematosus
that is con-
fined to the skin. It causes a red, itchy,
scaly rash to appear, particularly on the
face and scalp, behind the ears, and on
any parts of the body that are exposed
to sunlight. The disorder most com-
monly occurs in women between the
ages of 25 and 45, and tends to run in
families. Over a period of several years,
discoid lupus erythematosus may sub-
side and recur repeatedly with different
degrees of severity. Diagnosis is by a
skin
biopsy
,
and treatment is with topi-
cal corticosteroid drugs or drugs such
as hydroxychloroquine.
discoloured teeth
Teeth vary in colour from individual to
individual and, in general, secondary
teeth are darker in colour than primary
teeth. In addition, teeth often get dark-
er
with
age. The
term
discoloured
teeth, however, refers to teeth that are
abnormally coloured or stained.
EXTRINSIC STAINS
Extrinsic stains
(those found on the
tooth’s surface) are common. They are
usually
easily removed by polishing
and can be prevented by regular tooth
cleaning. Smoking tobacco produces a
brownish-black deposit on the teeth.
Pigment-producing bacteria can leave a
visible, usually green, line along the
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