BONE MARROW TRANSPLANT
BOTULISM
B
and on the presence of cells foreign to
the marrow. It is useful in the diagnosis
of many blood disorders, including
leu-
kaemia
and
anaemia.
It can also show
whether bone marrow has been invaded
by
lymphoma
or cells from other tumours.
bone marrow transplant
The techni-
que of using normal red
bone marrow
to replace cancerous or defective mar-
row in a patient. In allogeneic bone
marrow transplantation (BMT), healthy
bone marrow is taken from a donor who
has a very similar tissue-type to the
recipient's (usually a brother or sister).
In autologous BMT, the patient's own
healthy bone marrow is harvested while
his or her disease is in remission and is
reinfused later. BMT is used only in the
treatment of serious, mostly potentially
fatal, blood and immune system disor-
ders, including severe aplastic anaemia
(see
anaemia, aplastic), sickle cell anae-
mia,
and
leukaemia.
An
alternative
treatment is
stem-cell
transplantation,
in which cells from the umbilical cord of
a newborn baby or bloodstream of an
adult are used instead of bone marrow.
Before transplantation, all of the reci-
pient's marrow is destroyed by
cytotoxic
drugs
or radiation in order to prevent
rejection of the donated cells and to kill
any cancer cells present. The donor
bone marrow is transfused into the cir-
culation from where cells find their way
to the bone marrow cavities and start to
grow. In autologous BMT, the patient's
bone marrow is stored by
cryopreserva-
tion.
Before being frozen, the marrow is
usually treated to eliminate any unde-
tected cancerous cells. If the patient's
disease recurs, the stored marrow can
then be reinfused.
The major risks with BMT are infection
during the recovery period and rejection
(known as
graft-versus-host disease,
or
GVHD).
Immunosuppressant drugs
are
used to prevent and treat rejection. The
risk of GVHD may be reduced by remov-
ing the
T-cells
from the bone marrow
using monoclonal antibodies (see
anti-
body
,
monoclonal
) before reinfusion.
GVHD does not occur with allogeneic
BMT or stem-cell transplantation.
bone tumour
A bone swelling that may
be cancerous (see
bone cancer
) or non-
cancerous. The most common type of
noncancerous bone tumour is an
osteo-
chondroma.
Other types are
osteoma
and
chondroma (see
chondromatosis
). Treat-
ment is only necessary if the tumour
becomes very large or causes symptoms
by pressing on other structures. In such
cases, the tumour can be removed by
surgery. Osteoclastoma (also called a
giant cell tumour), which usually occurs
in the arm or leg of a young adult, is ten-
der and painful and has to be removed.
booster
A follow-up dose of
vaccine,
given to reinforce or prolong immunity
after an initial course of
immunization
.
borborygmi
see
bow el sounds.
borderline personality disorder
A
personality disorder that falls between
neurotic and psychotic levels. Mood
changes are often rapid and inappro-
priate. Angry outbursts are common, as
are impulsive, self-damaging acts such
as gambling or suicide attempts.
Bornholm disease
One of the names
for epidemic
pleurodynia
, an infectious
viral disease that is characterized by
severe chest pains and fever.
bottle-feeding
Infant feeding using a
milk preparation usually based on mod-
ified cow's milk. Formula milk contains
similar proportions of protein, fat, lac-
tose (milk sugar), and minerals as those
in human milk, but it lacks the protective
antibodies that are present in breast
milk. Vitamins are added. Bottle-fed
babies are at higher risk of gastrointes-
tinal infections than breast-fed babies
and may be more likely to develop aller-
gic disorders. (See also
feeding
,
infant
.)
botulinum toxin
A potentially lethal
toxin produced by the bacterium
CLOS-
tridium Botulinum
(see
botulism).
In
tiny doses, botulinum toxin is used as a
drug to control muscle spasms in some
disorders
(see
blepharospasm; facial
spasm
). It is also sometimes injected
into facial muscles to reduce visible
wrinkles temporarily.
botulism
A rare but serious form of poi-
soning caused by eating improperly
canned or preserved food contaminated
with a toxin produced by the bacterium
CLOSTRIDIUM BOTULINUM.
The toxin causes
progressive muscular paralysis as well
as other disturbances of the central and
88
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