TRANSILLUMINATION
T
tra n s illu m in a tio n
A p r o c e d u r e t h a t i s s o m e t i m e s c a r r i e d
o u t d u r i n g t h e p h y s i c a l e x a m i n a t i o n o f
a
l u m p
o r
s w e l l i n g .
L i g h t
t h a t
c o m e s
f r o m a s m a l l t o r c h i s s h o n e o n t o o n e
s i d e
o f t h e l u m p ;
i f t h e l i g h t
c a n b e
s e e n o n t h e o t h e r s i d e , t h e l u m p c o n -
t a i n s c l e a r f l u i d .
t ra n s itio n a l c e ll c a rc in o m a
A t y p e
o f c a n c e r o u s
t u m o u r
t h a t
c a n
d e v e l o p i n t h e b l a d d e r o r k i d n e y . I n t h e
b l a d d e r ,
t r a n s i t i o n a l
c e l l
c a r c i n o m a s
d e v e l o p w i t h i n t h e b l a d d e r l i n i n g
( s e e
b la d d e r t u m o u r s ).
I n t h e k i d n e y ( s e e
k id -
n e y c a n c e r ),
t h i s
t y p e
o f
t u m o u r
d e v e l o p s i n t h e l i n i n g o f t h e r e n a l p e l v i s
( t h e
u r i n e - c o l l e c t i n g
c h a m b e r
a t
t h e
c e n t r e o f t h e k i d n e y ) .
tra n s lo c a tio n
A
r e a r r a n g e m e n t
o f t h e
c h ro m o s o m e s
i n s i d e a p e r s o n ’s
c e l l s ;
i t i s a t y p e
o f
m u ta tio n .
S e c t i o n s o f c h r o m o s o m e s m a y
b e e x c h a n g e d o r t h e m a i n p a r t s o f t w o
c h r o m o s o m e s m a y b e j o i n e d . A t r a n s l o -
c a t i o n m a y b e i n h e r i t e d o r a c q u i r e d a s
t h e r e s u l t o f a n e w m u t a t i o n .
I n m a n y c a s e s a t r a n s l o c a t i o n h a s n o
o b v i o u s e f f e c t , a n d c a u s e s n o a p p a r e n t
a b n o r m a l i t y .
H o w e v e r ,
i t
s o m e t i m e s
m e a n s
t h a t s o m e
o f t h e a f f e c t e d p e r -
s o n ’s s p e r m o r e g g c e l l s c a r r y t o o m u c h
o r
t o o
l i t t l e
c h r o m o s o m a l
m a t e r i a l ,
w h i c h m a y c a u s e a
c h ro m o s o m a l a b n o r -
m a lity ,
s u c h a s
D o w n ’s s y n d ro m e ,
i n t h e
i n d i v i d u a l ’s c h i l d r e n .
tra n s m is s ib le
A
t e r m
m e a n i n g
c a p a b l e
o f
b e i n g
p a s s e d f r o m o n e p e r s o n , o r o n e o r g a n -
i s m , t o a n o t h e r .
tra n s p la n t s u rg e ry
R e p l a c e m e n t o f a d i s e a s e d o r g a n o r t i s s u e
w i t h a h e a l t h y , l i v i n g s u b s t i t u t e . T h e o r g a n
i s u s u a l l y t a k e n f r o m a p e r s o n w h o h a s
j u s t d i e d . S o m e k i d n e y s a r e t r a n s p l a n t e d
f r o m a p a t i e n t ’s l i v i n g r e l a t i v e s ( s e e
o r g -
an d o n a t io n ).
T h e r e s u l t s o f s u r g e r y h a v e
b e e n
i m p r o v e d
b y
t e s t i n g
f o r
h is t o -
c o m p a t ib ilit y a n tig e n s
a n d
t is s u e -t y p in g .
R e je c tio n
i s a m a j o r p r o b l e m . A c o m
-
b i n a t i o n o f a
c o rt ic o s t e ro id d ru g
a n d a n
im m u n o s u p p r e s s a n t d ru g
a r e
g i v e n
i n
o r d e r t o s u p p r e s s t h i s r e s p o n s e .
E v e r y p a t i e n t w h o h a s t o u n d e r g o a n
o r g a n
t r a n s p l a n t
o p e r a t i o n
m u s t
b e
g i v e n i m m u n o s u p p r e s s a n t d r u g s f o r a n
i n d e f i n i t e p e r i o d .
( S e e
a l s o
h e a r t - lu n g
t ra n s p la n t; h e a rt tra n s p la n t; k id n e y tra n s -
p la n t; liv e r t r a n s p la n t .)
EFFECT OF CHROMOSOMAL TRANSLOCATION
A translocation is a rearrangement ofthe chromosomes in body cells. A person
carrying a translocation may show no abnormality but there is a risk of his or her
child having a chromosomal abnormality.
Normal cell
A body cell normally contains 22 paired
chromosomes (called autosomes) plus
two sex chromosomes (XXin women and
XY in men). Just two pairs of autosomes -
numbers 14 and 21 - are shown here.
Example of translocation
In a typical translocation, a large part of one
ofthe chromosomes is joined to a large part of
another. In this particular example, most of
chromosome number 21 and chromosome
number 14 are joined together.
Balanced translocation (parent)
The remaining bits of chromosomes 21 and
14 disappear. If, as is illustrated here, the
translocation is balanced - that is, the total
amount ofchromosomal material is normal or
very close to the normal situation - no outward
abnormality is seen.
Eggs or sperm
produced
A parentwith the above
translocation makes four
types of egg or sperm.
They are (from left) -
normal, missing a
chromosome 21, carrying
joined chromosomes 14
and 21, and the same with
an extra chromosome 21.
Normal egg or sperm
An egg or sperm from
the parentwith the
translocation combines
with one from the other
parent, which has one
number 21 and one
number 14 chromosome.
Any of the four outcomes
below may result.
1
2
The effect in the child
The child may have any ofthe following:
(1) normal chromosomes, (2) a missing
chromosome 21 (incompatible with life),
(3) a balanced translocation (like the parent),
3
4
and (4) effectively, an extra chromosome 21,
leading to Down’s syndrome. In the last case,
the parents ofthe affected child maybenefit
from genetic counselling.
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