Biomedical Engineering Reference
In-Depth Information
COO
-
COO
-
C
NH
3
+
H
C
NH
3
+
H
CH
2
C
Asparaginase
CH
2
COO
-
H
2
O
NH
4
+
H
2
N
O
Aspartic acid
Asparagine
(a)
COO
-
COO
-
COO
-
COO
-
NH
3
+
NH
3
+
H
H
Glutamine
amidotransferase
NH
3
+
H
NH
3
+
H
C
C
C
C
+
+
CH
2
COO
-
(CH
2
)
2
C
CH
2
C
(CH
2
)
2
COO
-
ATP
H
2
O
AMP
+ PPi
H
2
N
O
H
2
N
O
Glutamine
Asparagine
Glutamic acid
Aspartic acid
(b)
Figure 12.14
(a) Hydrolytic reaction catalysed by
L
-asparaginase. (b) Reaction by which asparagine is syn-
thesized in most mammalian cells
12.5.2 DNase
Recombinant DNase preparations have been used in the treatment of cystic fi brosis since the end
of 1993. This genetic disorder is common, particularly in ethnic groups of northern European
extraction, where the frequency of occurrence can be as high as 1 in 2500 live births. A higher
than average incidence has also been recorded in southern Europe, as well as in some Jewish and
African-American populations.
A number of clinical symptoms characterize cystic fi brosis. Predominant among these is the
presence of excess sodium chloride in cystic fi brosis patient sweat. Indeed, measurement of chlo-
ride levels in sweat remains the major diagnostic indicator of this disease. Another characteristic
is the production of an extremely viscous, custard-like mucus in various body glands/organs that
severely compromises their function. Particularly affected are:
•
The lungs, in which mucus compromises respiratory function.
•
The pancreas, in which the mucus blocks its ducts in 85 per cent of cystic fi brosis patients, caus-
ing pancreatic insuffi ciency. This is chiefl y characterized by secretion of greatly reduced levels
of digestive enzymes into the small intestine.
•
The reproductive tract, in which changes can render males, in particular, subfertile or infertile.
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