The effect of low-dose heparin on fibrinopeptide A, platelets, fibrinogen degradation products and other haemostatic parameters measured in connection with intestinal surgery.
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Aged↗
Biomedical subjects
I Norén
Publications and source records attributed to I Norén.
Vacutainer sampling for blood coagulation assays.
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Aminocaproic Acid↗
[Coagulation screening: P-APT-time (APTT) -- new reagents, improved method?].
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Adult↗
Use of a lyophilized reference plasma to compare coagulation test procedures: Normotest, Simplastin-A and Thrombotest.
In 4 collaborative trials, involving a varying number of hospital laboratories in the Stockholm area, the coagulation activity of different test materials was estimated with the one-stage prothrombin tests routinely used in the laboratories, viz. Normotest, Simplastin-A and Thrombotest. The test materials included different batches of a lyophilized reference plasma, deep-frozen specimens of diluted and undiluted normal plasmas, and fresh and deep-frozen specimens from patients on long-term oral anticoagulant therapy. Although a close relationship was found between different methods, Simplastin-A gave consistently lower values than Normotest, the difference being proportional to the estimated activity. The discrepancy was of about the same magnitude on all the test materials, and was probably due to a divergence between the manufacturers' procedures used to set "normal percentage activity", as well as to a varying ratio of measured activity to plasma concentration. The extent of discrepancy may vary with the batch-to-batch variation of thromboplastin reagents. The close agreement between results obtained on different test materials suggests that the investigated reference plasma could be used to calibrate the examined thromboplastin reagents, and to compare the degree of hypocoagulability estimated by the examined PIVKA-insensitive thromboplastin reagents. The assigned coagulation activity of batches of the reference plasma agreed closely with experimentally obtained values. The stability of supplied batches was satisfactory as judged from the reproducibility of repeated measurements. The variability of test procedures was approximately the same on different test materials.
Anticoagulants↗
Assessment of different mathematical models for calculating and expressing the results of coagulation test procedures.
Coagulation activity, expressed as percentage of normal and as clotting time ratio, was estimated in 220 specimens from patients on long-term anticoagulant treatment by 3 different coagulation test procedures, i.e. Thrombotest, Simplastin-A and Normotest. The estimates were calculated from the same determinations. The distribution of percentage values showed a fairly pronounced deviation from normality. After logarithmic transformation, the distribution was normalized, the regression lines between Thrombotest and other tests became parallel, and that between PIVKA-insensitive systems was shifted to a 45 degree line. Logarithmic transformation also stabilized the residual variance. These features make percentage values accessible for treatment according to the standard methods of bioassay statistics. Attempts to normalize the distribution of ratio values by various transformations were unsuccessful. Formal analysis of data revealed a variation in the proportionality of ratio values with the level of estimated coagulation defect. This may restrict the usefulness of the ratio approach. Logarithmic transformation partly reduced the discrepancy.
Analysis of Variance↗
Fibrin plate method with reagents purified by affinity chromatography and its use for determination of fibrinolytic and other proteolytic activity in saliva, bile and plasma.
A modification of the fibrin plate method is presented. Plasminogen-free human fibrinogen and plasminogen purified by affinity chromatography have been used. Fibrin plates without and with a constant amount of plasminogen and with agarose as stabilizing medium were used for the estimation of plasmin and plasminogen activator activity. Activator activity could be demonstrated in sterile bile and saliva. When plasmin activity was present, estimations of plasminogen activator were approximate. The method is sensitive, small volumes of reagents and samples are needed. The error of the method is comparatively low and the reproducibility is good.
Bile↗