SummaryThe partial thromboplastin time (PTT) test is widely used as a screening test for the detection of hemophilia. It is also used to monitor patients on heparin anticoagulation. This proposal from a ICSH Panel proposes guidelines for the performance of this test, including comparable reference ranges, precision and sensitivity requirements.
Partially denatured main isoenzyme com- Key Words
ponent of alcohol dehydrogenase from horse liver separates Denaturation of horse
into three peaks on chromatography on Sephadex G-150, liver alcohol dehydrogenase
with relative elution volume (Ve/Vo) values of 1.7,1.3 and in urea
1.0, respectively. The peak with Ve/Vo value of 1.7 consists
of the native enzyme. The components of the peak with Ve/Vo value of 1.3 are able to
form the native enzyme under suitable techniques and, therefore, may represent enzyme
subunits, or possibly protein aggregates. The peak with Ve/Vo value of 1.0 probably
represents subunit aggregates. The fact that reassociable forms of the enzyme are excluded
by Sephadex G-150 in front of the native enzyme suggests that dissociation in urea is
accompanied by considerable unfolding of the native structure. The denaturation rate is
faster at 4 than at 20°C and aggregate formation is also faster at 4 then at 20°C. The rate
of dénaturation of the enzyme, as determined by electrophoresis and scanning, is highly
dependent on the purity of urea.
A variety of methods are used to measure plasma fibrinogen, the clottable protein methods being the most widely used in the United States. A review of the strengths and weaknesses of currently available functional as well as immunological fibrinogen methods indicates that the ideal methods has not yet been found. There is some need for a rapid yet simple in-house reference method since the kit purchasers are unduly subject to external, i.e., commercial, standardization.
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