I
HUNGER
develop in the placenta, disrupting the
blood supply to the fetus and causing
m i s c a r r i a g e
; affected women may have
several consecutive miscarriages.
TREATMENT AND OUTLOOK
Hughes’ syndrome is treated with drugs
that reduce the tendency of the blood to
clot: aspirin, heparin, or warfarin. Treat-
ment is long-term or even lifelong, but
greatly improves the outlook. It enables
people to lead a completely normal life
and, in women of childbearing age, dras-
tically reduces the risk of miscarriage.
h u m a n c h o rio n ic g o n a d o tro p h in
See
g o n a d o t r o p h i n , h u m a n c h o r i o n i c .
h u m a n g a m m a -g lo b u lin
See
g a m m a - g l o b u l i n .
h u m a n g e n o m e
See
g e n o m e , h u m a n .
h u m a n le u k o c y te a n tig e n (H LA)
A protein that belongs to the group of
proteins called
h i s t o c o m p a t i b i l i t y a n t i g e n s ,
w hich play a role in the
i m m u n e s y s t e m
.
h u m a n p a p illo m a v iru s
A type of
v i r u s
that is responsible for
w a r t s
and
g e n i t a l
warts.There are over
7
0
subtypes of human papillomavirus. At
least two of these subtypes are thought
to be a causative factor in
c e r v i c a l c a n c e r
and anal cancer.
h u m a n T -c e ll ly m p h o tro p ic v iru s
A type of retrovirus, also called human
T-cell leukaemia virus or HTLV There
are several types of HTLV, the most
common of w hich is HTLV-
1
, w hich is
endemic in tropical regions, including
southern Japan, the Caribbean, South
America, and West Africa. The virus can
be transmitted by sexual contact, breast-
feeding, a transfusion of contaminated
blood, or by intravenous drug users
who share contaminated needles.
SYMPTOMS AND TREATMENT
Most people who become infected with
HTLV
-1
have no symptoms, but a small
percentage (less than one in 20) may
develop
serious
disorders.
One such
disorder
is
the
cancerous
condition
adult
T-cell
leukaemia,
w hich
may
appear up to
20
years after infection. In
this disease, there is a rapid and abnor-
mal turnover of white blood cells in the
bone marrow and of cells in lymphoid
tissue. Typically,
l y m p h n o d e s ,
the
l i v e r ,
and the
s p l e e n
are enlarged.
A n t i c a n c e r
d r u g s
may halt the condition temporari-
ly, by killing abnormal cells, but people
tend to survive for only a few months
to a few years.
Another
condition
associated with
HTLV
-1
is
m y e l o p a t h y
(spinal cord dis-
ease). This condition causes pain in the
lower back and legs, together with pro-
gressively worsening weakness of the
legs and difficulty in walking.
h u m e ru s
The bone of the upper arm. The dome-
shaped head of the bone lies at an angle
to the shaft and fits into a socket in the
s c a p u l a
(shoulderblade)
to
form
the
s h o u l d e r
joint. Below its head, the bone
narrows to
form
a cylindrical shaft,
w hich has a spiral groove housing the
r a d i a l n e r v e
(one of the main nerves in the
arm, running from the shoulder to the
hand). It flattens and widens at its lower
end, forming a prominence on each side
called an
e p i c o n d y l e .
At its base, it artic-
ulates with the
u l n a
and the
r a d i u s
(the
bones of the forearm) to form the
e l b o w .
h u m e ru s , fra c tu re o f
The
h u m e r u s
(upper arm bone) is most
commonly fractured at its neck
(the
upper end of the shaft, below the head),
particularly in elderly people. Fractures of
the shaft occur in adults of all ages. Frac-
tures at the lower end of the humerus
occur most commonly in children.
COMPLICATIONS
Certain complications may arise if the
broken bone ends are displaced and dam-
age surrounding tissues. A fracture in the
shaft of the humerus can result in dam-
age to the radial nerve; in severe cases,
this damage may lead to wrist-drop. Frac-
tures may also be associated with damage
to the brachial artery, which runs down
the inner side of the upper arm. If such
damage goes undetected, the blood cir-
culation to the forearm and hand may be
impaired, resulting in a deformity called
Volkmann’s contracture.
Some supracondylar fractures (breaks
just above the elbow) fail to heal prop-
erly despite treatment. As a result, the
elbow may be deformed and there is an
increased risk that
o s t e o a r t h r i t i s
may
subsequently develop in the joint.
DIAGNOSIS AND TREATMENT
An
X - r a y
can show a fracture of the
humerus. A fracture at the neck of the
bone usually requires only a
s l i n g
to
immobilize the bone; a fracture of the
shaft or lower bone normally needs a
plaster
c a s t .
Most
fractures
of
the
humerus heal in six to eight weeks.
h u m o ra l im m u n ity
A state of protection against disease that
is brought about by the production of
antibodies by the immune system to
combat infection. In contrast, cellular
immunity is the direct response of lym-
phocytes (a type of white blood cell) to
infection and abnormal cells in the body
h u m o u rs
A term that describes any liquid or jelly-
like substance in the body Humours
usually refers to the
a q u e o u s h u m o u r
and
v i t r e o u s h u m o u r
that occur in the
e y e
.
h u n c h b a c k
See
k y p h o s i s .
h u n g e r
A disagreeable feeling caused by the
need
for
food;
it
is
different
from
a p p e t i t e ,
w hich is a pleasurable sensation
caused by the presence of food. Hunger
occurs when the stomach is empty and
the blood
g l u c o s e
level is low, which
may occur several hours after the last
meal or following strenuous exercise.
In response to these stimuli, messages
from the
h y p o t h a l a m u s
in the brain cause
the muscular stomach wall to contract
rhythmically; these contractions, if they
are pronounced enough, can produce
hunger pains.
H
389
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