Development of a photometric assay for activated partial thromboplastin time and its application to the cobas(R) biocentrifugal analyzer

Becker, U.; Bartl, Knut; Lill, Helmut; August, Wilhelm

doi:10.1016/0049-3848(85)90310-x

Cited by 10 publications

(7 citation statements)

References 11 publications

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“…The starting re agent (20 pi of Chromozym TH and calcium acetate) was automatically added after 280 s of preincubation at 37 °C. The change in extinction was registered at 405 nm at time intervals of 10 s over a period of 300 s [7], The extinction data were transferred from the instrument on-line to the computer system for com prehensive analysis.…”

Section: Measurement O F the Intrinsic Clotting Systemmentioning

confidence: 99%

“…The resolution of the amino acid sequence of various clot ting factors has led to the synthesis of spe cific chromogenic substrates [4] which are now being preferentially used as indicators. Recently developed methods enable the ki netics of the cascade reaction to be followed by photometry [5][6][7] or fluorometry [8], De spite these advantages there is still little known about the change in the overall kinet ics of the cascade reaction in different factor deficiencies, since the measurement with chromogenic substrates is based on the prin-Baumann/Jurgensen/Hcuck Time, s Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

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Computerized Analysis of the in vitro Activation of the Plasmatic Clotting System

Baumann

Jürgensen²,

Heuck³

1989

Pathophysiol Haemos Thromb

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We analyzed the kinetics of the clotting system by a chromogenic substrate method in plasma with isolated factor deficiency. The sigmoidal extinction curve obtained was mathematically described by an equation with four constants K(i) relating to the activity of clotting factors and to the concentration of fibrinogen. The analysis of constants obtained from dilution series of factor-deficient plasma revealed a distribution pattern differing from one factor to another both for the extrinsic and the intrinsic system. The observations indicated that isolated factor deficiency may be identified through the analysis of 2 of the 4 constants, K(1) being the time value of the point of inflection of the extinction curve and K(2) a measure for the slope of the curve at the point of inflection. The observation was confirmed by a reclassification through nearest-neighbor discriminant analysis of K(1) and K(2) which revealed a correct classification in the pathological range for all factor deficiencies investigated with the exception of factors VIII and IX, the distribution patterns of which were superposed within the limits of distribution.

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Section: Measurement O F the Intrinsic Clotting Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Computerized Analysis of the in vitro Activation of the Plasmatic Clotting System

Baumann

Jürgensen²,

Heuck³

1989

Pathophysiol Haemos Thromb

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“…heparin (data not shown) and in samples of heparinized patients, for whom laboratory control was requested during the evaluation period (n = 28, r = 0.71, y = 1,8x -11). The sensitivity of the TQ-PT and TQ-aPTT for isolated clotting factor deficiencies was high [6,7], We found that mixtures of normal plasma and factor-deficient plasma with a factor VIII activity lower than 55% or a fac tor IX activity lower than 70% gave TQaPTT values outside the reference interval. The sensitivity for factor VIII was confirmed by patient plasmas with a factor VIII defi ciency (table II).…”

Section: Clinical Evaluation O F the Global Photometric Clotting Assaysmentioning

confidence: 99%

“…1). For the TQ-aPTT such a dilution curve is nonlinear [7], The kinetic fibrinogen assay was linear, when fresh patient plasma was used for the determination of various plasma dilutions.…”

Section: Accuracy Reproducibility and Linearitymentioning

confidence: 99%

“…A Cobas Bio centrifugal analyzer (Hoffmann-La Roche), coupled to an external calculator (Epson HX 20) was used for the Thromboquant PT (TQ-PT) [6], the Thromboquant aPTT (TQ-aPTT) [7] and the kinetic fibrinogen [8] determination according to the manufacturer's prescription (Boehringer-Mannheim, FRG). The TQ-PT and the TQ-aPTT used rabbit brain thromboplastin/Ca2* and cllagic acid/phospholipids as activator, respectively.…”

Section: Photometric Assaysmentioning

confidence: 99%

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Use of a Centrifugal Analyzer for a Chromogenic Prothrombin Time, a Chromogenic Activated Partial Thromboplastin Time and a Kinetic Fibrinogen Assay in a Routine Hospital Laboratory

Metz¹,

Wersch²

1987

Pathophysiol Haemos Thromb

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A Cobas Bio® centrifugal analyzer was used in a clinical laboratory for the performance of chromogenic clotting assays. Three commercially available photometric clotting tests – prothrombin time (PT), activated partial thromboplastin time (aPTT) and fibrinogen – were compared with the traditional clotting assays during 3 months. No great discrepancies were found between the traditional assays and the new photometric assays. The chromogenic PT could replace the traditional thrombotest®, PT and Normotest®, because it was sensitive and accurate over a broad range of clotting factor activity. Furthermore the chromogenic PT could be used to discriminate between a decreased clotting activity due to vitamin K deficiency or to a decreased protein synthesis by the liver. A decreased protein synthesis was confirmed by measuring a decrease in the serum cholinesterase activity. The chromogenic aPTT could be used for the assay of heparin concentrations in the therapeutic range and turned out to be more sensitive for deficiencies of factor VIII and factor IX than a traditional clotting aPTT. We conclude that the accuracy and practicability of clotting assays are improved by the new assays without diminishing the clinical value of the results.

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Chromogenic substrates for activated partial thromboplastin time testing: Are they worth using?

Tripodi

1989

Res. Clin. Lab.

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Development of a photometric assay for activated partial thromboplastin time and its application to the cobas(R) biocentrifugal analyzer

Cited by 10 publications

References 11 publications

Computerized Analysis of the in vitro Activation of the Plasmatic Clotting System

Computerized Analysis of the in vitro Activation of the Plasmatic Clotting System

Use of a Centrifugal Analyzer for a Chromogenic Prothrombin Time, a Chromogenic Activated Partial Thromboplastin Time and a Kinetic Fibrinogen Assay in a Routine Hospital Laboratory

Chromogenic substrates for activated partial thromboplastin time testing: Are they worth using?

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