ISSN:0036-553X    

DOI:10.1111/j.1600-0609.1980.tb01337.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The need for standardization of methods for the control of anticoagulant therapy was apparent 25 years ago. With the development of the ratio method for comparing the sensitivity of different thromboplastin preparations it became possible to equate the value obtained with one preparation in terms of the value which would be obtained with any other preparation, and the need for a reference to serve as a yardstick for comparison became obvious. The first trial reference preparation was developed in 1965 and three small international trials on the calibration of different thromboplastin preparations were conducted. The first international reference preparation was laid down in 1967 coded 67/40, and other preparations containing ox brain, human brain and rabbit brain and coded 68/434, 69/223 and 70/178 followed. Further collaborative studies were carried out in 1970 and 1973, and a large international trial undertaken in 1974, using 70/178 as the reference preparation. These preparations have remained stable over a period of 9 to 12 years and their usefulness for purposes of calibration and international trials has been proven. Three further reference preparations were laid down in 1979 and a further international collaborative study has been undertaken.

ISSN:0036-553X    

DOI:10.1111/j.1600-0609.1980.tb01338.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Beginning in 1967, several committees have attempted to formulate a consensus opinion on how best to standardize the control of oral anticoagulant therapy.The three major proposals that evolved were: 1) to agree on a standard thromboplastin that would serve as a «reference thromboplastin», 2) to explore mathematical approaches for comparing the results obtained with various thromboplastins, and 3) the use of assayed plasmas that would serve as a common reference material for all thromboplastins.The advantages of reference plasmas as a common reference and their usefulness in the standardization of oral anticoagulant therapy are discusse

ISSN:0036-553X    

DOI:10.1111/j.1600-0609.1980.tb01339.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The thromboplastin concept of standardization of the prothrombin‐time according to Biggs and Denson survived criticism, obtained support from many countries, and recently proved to be applicable in the clinical practice of monitoring long‐term oral anticoagulation of the individual patient. Reference thromboplastins certified by the Bureau Communautaire de Référence of the European Economic Communities are now being produced, to be used in calibration by manufacturers of thromboplastin preparations. Assayed normal and abnormal plasmas will enable both manufacturers and clinical laboratories to implement the thromboplastin concept in the practice of prothrombin‐time standardization.The present basic World Health Organization reference thromboplastin human combined (preparation 67/40 of the British National Institute for Biological Standards and Control) is, for various reasons, supposed to be replaced by a thromboplastin human plain (a batch of British Comparative Thromboplastin) as soon as it becomes available and has been approved.Expression of the coumarin induced coagulation defect in terms of International Calibrated Ratios in addition to conventional terms will greatly facilitate understanding individual patient results as well as optimal therapeutic ranges to be aimed at.To create, for stability checking of reference thromboplastins and reference plasmas, stable reference points, unmistakable quantification of the coumarin‐induced enzyme defect is

ISSN:0036-553X    

DOI:10.1111/j.1600-0609.1980.tb01340.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The partial thromboplastin time (PTT) which is used as an overall measure of the intrinsic clotting system, is the commonest coagulation test employed in routine laboratories apart from the prothrombin time. The main functions of the test are: 1. to screen intrinsic coagulation defects; 2. to control heparin administration; 3. in the control of oral anticoagulant treatment.Many different preparations of phospholipid of human, animal and vegetable origin are used as PTT reagents. In addition, different activators, incubation times, concentrations of calcium chloride and test dilutions of plasma and phospholipid are recommended for routine laboratory use. The need to standardise both reagents and technique has been emphasised in many reports. To meet the need for a reference preparation for the PTT test, a large batch of phospholipid material of human brain origin, designated 71/25, was prepared in the National (UK) Reference Laboratory in lyophilised form in 1971 and proposed as a provisional international reference material. This primary master preparation has been used to calibrate subsequent batches of secondary reference preparations distributed to hospitals in the UK and overseas. Results of a number of collaborative studies have demonstrated the greater reliability of the standardised PTT extract compared with commercial extracts used at the same centres in the three aspects of PTT testing.The conclusion to be drawn from these extensive studies of the laboratory and clinical application of the provisional international reference preparation (71/25) is that we may now be in a position to define an acceptable international standard for the APTT.

ISSN:0036-553X    

DOI:10.1111/j.1600-0609.1980.tb01341.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

A study has been carried out in two stages to compare the sensitivity of different Partial Thromboplastin Time (P.T.T.) methods to partial deficiencies of factor VIII. In Stage1, 63 laboratories throughout the world compared their own methods with a reference method, all using samples of the same three mild haemophilic plasmas. Wide variation was found between laboratories using the same method, especially for those methods which were not well standardised. There was fairly good agreement for the reference method. All methods correctly diagnosed the three mild haemophilic plasmas, but their factor VIII levels were rather low.Stage 2 was restricted to seven laboratories in Great Britain, comparing seven well‐standardised commercial methods and the same reference method. A much wider range of abnormal plasmas was tested, and a variety of normal ones. P.T.T.'s for all plasmas (factor VIII levels from 5 to 58 iu/dL) fell outside the normal range by all methods, with a few exceptions. It was not possible to rank the methods in any orde

ISSN:0036-553X    

DOI:10.1111/j.1600-0609.1980.tb01342.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Collaborative studies to measure the effect of heparin on the activated partial thromboplastin time (APTT) have been conducted by the National (UK) Reference Laboratory for Anticoagulant Reagents and Control (NRLARC) in Great Britain and overseas and by the College of American Pathologists (CAP) in the United States. The value of multicentre trials to assess the various APTT methods, as opposed to single centre investigations, is discussed. Results from the NRLARC studies indicate that APTT methods from commercial manufacturers are relatively insensitive to heparin at low levels, compared with the standardised APTT reagent and technique produced by the NRLARC. The latter shows good sensitivity over a wide range of heparin concentrations. Variables encountered with the different commercial APTT methods are outlined. An APTT reagent should show good sensitivity at low levels and a linear response to a wide range of heparin concentrations. The in vivo response of the NRLARC standardised method in detecting circulating heparin during a clinical study of low‐dose heparin prophylaxis during surgery has also been evaluate

ISSN:0036-553X    

DOI:10.1111/j.1600-0609.1980.tb01343.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The Duke, Ivy and immersion methods for performing the bleeding time are reviewed and modifications of these methods are discussed. Certain of the automated devices are described. It is concluded that the bleeding time, when properly standardized, is an important test in the evaluation of a hemostatic disorder.

ISSN:0036-553X    

DOI:10.1111/j.1600-0609.1980.tb01344.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

In a previous work, we have compared two automated techniques for platelet‐rich plasma using a thrombocounter or whole blood with the continuous flow instrument Auto‐analyzer (AA). More recently, we have tested two instruments using whole blood: the first one, fully automated: Coulter S+; and the other one, semi‐automated: Clay‐Adams. In the present work, these 4 methods are compared to the phase contrast microscope technique, used as reference. The coefficients of variation ranged betweeen 2 and 13 per cent. The coefficients of correlation between the different methods were between 0.92 and 0.96. Platelet distribution curves for platelet volumes obtained in parallel with platelet‐rich plasma and with whole blood in 30 controls, show that platelet population are not significantly different. These instruments count particles and, therefore, necessitate a calibration made by means of platelet standards. Different platelet standards have been studied: those containing latex particles seem to give better results than suspensions of human or animal

ISSN:0036-553X    

DOI:10.1111/j.1600-0609.1980.tb01345.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Because of the need to relate haemophilic samples to the normal population, the unit of Factor VIII clotting activity (VIII:C) was first defined as the amount in 1 ml. of normal plasma. However, because of wide variation in the normal population, and poor stability of VIII:C in plasma, pooled normal plasma is unsuitable as a reference standard for Factor VIII. The 1st International Standard for Factor VIII was established in 1970 to provide a stable reference material. It consisted of a freeze‐dried intermediate‐purity concentrate, and its potency was established by comparison with fresh normal plasma in a large number of laboratories. This standard was replaced in 1976 by the 2nd International Standard, also a stable intermediate purity concentrate. These long‐term reference standards are intended for calibration of working standards, and for manufacturers of concentrates it is preferable to use concentrates as working standards, because of the desirability of assaying «like against like». For assay of patients' plasmas, a plasma standard is necessary, and in the U.K. successive batches of British plasma standards have been calibrated against the International Standard (concentrate) by several laboratories. However, calibration of these plasmas against the concentrate standard has been shown to give substantial discrepancies between laboratories, and an overall discrepancy of 20% between one‐stage and two stage assays. Although standardisation of reagents and technique has improved agreement between laboratories, discrepancies still remain, and these could be markedly diminished by establishment of a plasma reference standard, to exist alongside the concentrate standard. Improvements in methods of handling have led to better stability of Factor VIII in freeze‐dried plasma and it is now planned to establish a stable reference plasma for VIII:C. Such a plasma could also act as a reference for the other Factor VIII related activities, i.e. VIII related antigen, VIII clotting antigen, and VIII ristoceti

ISSN:0036-553X    

DOI:10.1111/j.1600-0609.1980.tb01346.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY