An International Standard for whole blood folate: evaluation of a lyophilised haemolysate in an international collaborative study

2004 ◽  
Vol 42 (5) ◽  
Author(s):  
Susan J. Thorpe ◽  
Dawn Sands ◽  
Alan B. Heath ◽  
Malcolm S. Hamilton ◽  
Sheena Blackmore ◽  
...  
Keyword(s):  
Whole Blood ◽  
Collaborative Study ◽  
World Health ◽  
Expert Committee ◽  
International Standard ◽  
Accelerated Degradation ◽  
Biological Standardization ◽  
The World ◽  
Health Organization ◽  
International Collaborative Study

AbstractFolate measurements, particularly for whole blood, show wide inter-laboratory and inter-methodology variability. This variability appears to be due in part to the lack of internationally accepted reference materials. A whole blood haemolysate, lyophilised in ampoules and designated 95/528, was therefore evaluated by 15 laboratories in five countries for its suitability as an International Standard (IS) for whole blood folate. The preparation was assayed using a variety of microbiological and protein-binding methodologies against local standards and calibrators. A consensus folate content was assigned to 95/528. The inclusion of three whole blood samples in the study with widely differing folate levels demonstrated a considerable reduction in inter-laboratory variability when the folate content of the samples was determined relative to the proposed IS 95/528 rather than to laboratories' local standards and calibrators. Accelerated degradation studies indicated that the folate content of 95/528 is stable when stored at −20°C. On the basis of the results presented here, the World Health Organization Expert Committee on Biological Standardization established 95/528 as an IS for whole blood folate.

A Collaborative Study to Establish the Second International Standard for Streptokinase

1990 ◽  
Vol 64 (02) ◽  
pp. 267-269 ◽  
Author(s):  
A B Heath ◽  
P J Gaffney
Keyword(s):  
High Purity ◽  
Collaborative Study ◽  
World Health Organisation ◽  
World Health ◽  
Clot Lysis ◽  
Current Standard ◽  
International Standard ◽  
Accelerated Degradation ◽  
The World ◽  
International Collaborative Study

SummaryAn International Standard for Streptokinase - Streptodomase (62/7) has been used to calibrate high purity clinical batches of SK since 1965. An international collaborative study, involving six laboratories, was undertaken to replace this standard with a high purity standard for SK. Two candidate preparations (88/826 and 88/824) were compared by a clot lysis assay with the current standard (62/7). Potencies of 671 i.u. and 461 i.u. were established for preparations A (88/826) and B (88/824), respectively.Either preparation appeared suitable to serve as a standard for SK. However, each ampoule of preparation A (88/826) contains a more appropriate amount of SK activity for potency testing, and is therefore preferred. Accelerated degradation tests indicate that preparation A (88/826) is very stable.The high purity streptokinase preparation, coded 88/826, has been established by the World Health Organisation as the 2nd International Standard for Streptokinase, with an assigned potency of 700 i.u. per ampoule.

scholarly journals International collaborative study to evaluate a recombinant L ferritin preparation as an International Standard

1997 ◽  
Vol 43 (9) ◽  
pp. 1582-1587 ◽  
Author(s):  
Susan J Thorpe ◽  
Dawn Walker ◽  
Paolo Arosio ◽  
Alan Heath ◽  
James D Cook ◽  
...  
Keyword(s):  
Collaborative Study ◽  
Expert Committee ◽  
Immunological Reactivity ◽  
International Standard ◽  
Accelerated Degradation ◽  
Wide Range ◽  
Biological Standardization ◽  
International Collaborative ◽  
Degradation Studies ◽  
International Collaborative Study

Abstract A recombinant L ferritin preparation, lyophilized in ampoules and designated 94/572, was evaluated by 18 laboratories in 9 countries for its suitability as an International Standard (IS). The preparation was assayed in a wide range of in-house and commercial immunoassays against the 2nd IS for ferritin (of spleen origin; 80/578). The immunological reactivity of the recombinant material was similar to that of the 2nd IS for ferritin in the majority of assays and demonstrated adequate stability in accelerated degradation studies. On the basis of the results presented here, the WHO Expert Committee on Biological Standardization established 94/572 as the 3rd IS for ferritin, recombinant.

A Collaborative Study of a Proposed International Standard for Tissue Plasminogen Activator (t-PA)

1985 ◽  
Vol 53 (01) ◽  
pp. 134-136 ◽  
Author(s):  
P J Gaffney ◽  
A D Curtis
Keyword(s):  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Collaborative Study ◽  
International Committee ◽  
World Health ◽  
Clot Lysis ◽  
Expert Committee ◽  
International Standard ◽  
Tissue Plasminogen ◽  
Health Organization

SummaryAn international collaborative study involving seven laboratories was undertaken to assess which of three lyophilised preparations might serve as an International Standard (I.S.) for tissue plasminogen activator (t-PA). Two of the preparations were isolates from human melanoma cell cultures while one was of pig heart origin. A clot lysis assay was used by all participants in the study.The data suggested that both preparations of human cell origin were comparable, in that their log dose-response lines were parallel, while that of the porcine preparation was not. Accelerated degradation studies indicated that one melanoma extract (denoted 83/517) was more stable than the other and it was decided to recommend preparation 83/517 as the standard for t-PA. The International Committee for Thrombosis and Haemostasis (Stockholm 1983) has recommended the use of this material as a standard and it has been established by the Expert Committee on Biological Standardization of the World Health Organization as the International, Standard for tissue plasminogen activator, with an assigned potency of 1000 International Units per ampoule.

The Second International Reference Preparation of Thyroid-Stimulating Hormone, Human, for Immunoassay: calibration by bioassay and immunoassay in an international collaborative study

1985 ◽  
Vol 104 (3) ◽  
pp. 367-379 ◽  
Author(s):  
R. E. Gaines Das ◽  
A. F. Bristow
Keyword(s):  
Collaborative Study ◽  
Thyroid Stimulating Hormone ◽  
World Health ◽  
Expert Committee ◽  
International Reference ◽  
Reference Preparation ◽  
International Collaborative ◽  
Health Organization ◽  
International Collaborative Study ◽  
Second International

ABSTRACT Four batches of ampouled materials in ampoules coded 80/558, 81/502, 81/565 and 81/615 were evaluated by 22 laboratories in nine countries in an international collaborative study for their suitability to serve as a replacement for the First International Reference Preparation (IRP) of TSH, Human, for Immunoassay. The ampouled preparations were calibrated by immunoassay and bioassay. The preparation coded 80/558 had satisfactory stability and contained acceptably low levels of contamination with FSH and LH. Estimates of the immunoreactive TSH content of a set of specimens of serum in terms of 80/558 showed agreement in ranking order and no increase in variability compared with estimates made by assay against the First IRP. On the basis of these results, with the agreement of the participants in the study, and with the authorization of the Expert Committee on Biological Standardization of the World Health Organization, the preparation coded 80/558 was established in 1983 as the Second International Reference Preparation of TSH, Human, for Immunoassay, with a defined potency of 37 mi.u./ampoule. Preparations coded 81/502, 81/565 and 81/615 were found suitable to serve as working standards. J. Endocr. (1985) 104, 367–379

An International Standard for holotranscobalamin (holoTC): international collaborative study to assign a holoTC value to the International Standard for vitamin B12 and serum folate

2016 ◽  
Vol 54 (9) ◽  
pp. 1467-1472 ◽  
Author(s):  
Susan J. Thorpe ◽  
Peter Rigsby ◽  
Graham Roberts ◽  
Anne Lee ◽  
Malcolm Hamilton ◽  
...  
Keyword(s):  
Vitamin B12 ◽  
Collaborative Study ◽  
World Health ◽  
Serum Folate ◽  
Expert Committee ◽  
Specific Marker ◽  
Serum Samples ◽  
International Standard ◽  
International Collaborative ◽  
International Collaborative Study

AbstractBackground:Investigation of possible B12 and folate deficiencies requires measurement of these vitamins in serum. There is evidence that holotranscobalamin (holoTC), the active portion of B12 available to cells, is a more specific marker of early B12 deficiency than total B12. The availability of immunoassays for holoTC prompted an international collaborative study to assign a holoTC value to the World Health Organization (WHO) 1st International Standard (IS) for vitamin B12 and serum folate, 03/178.Methods:The IS, 03/178, and three serum samples with different holoTC levels were assayed by 12 laboratories in eight countries using manual and automated immunoassays for holoTC; one laboratory additionally performed an in-house assay. Fourteen sets of data were analysed.Results:Overall, the IS, 03/178, and the three serum samples demonstrated assay linearity and parallelism. An overall geometric mean (GM) holoTC value of 106.8 pmol/L was obtained for 03/178, with an inter-laboratory geometric coefficient of variation (GCV) of 10.5%. There was a reduction in inter-laboratory variability when the holoTC levels in the serum samples were determined relative to the IS with an assigned holoTC value rather than to the assays’ calibration. Accelerated degradation studies showed that 03/178 was sufficiently stable to serve as an IS for holoTC.Conclusions:The WHO Expert Committee on Biological Standardization endorsed the proposal to assign a holoTC value of 107 pmol/L to 03/178, corresponding to 0.107 pmol per ampoule, for use as the 1st IS for vitamin B12, serum folate, and holoTC.

scholarly journals International collaborative study to evaluate and calibrate two recombinant L chain Ferritin preparations for use as a WHO International Standard

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Bernard Fox ◽  
Graham Roberts ◽  
Eleanor Atkinson ◽  
Peter Rigsby ◽  
Christina Ball
Keyword(s):  
Geometric Mean ◽  
Collaborative Study ◽  
Expert Committee ◽  
International Standard ◽  
Long Term Storage ◽  
Automated Assay ◽  
Accelerated Stability ◽  
Biological Standardization ◽  
International Collaborative ◽  
International Collaborative Study

Abstract Objectives To evaluate and calibrate two candidate preparations for the 4th International Standard for Ferritin (Human, Recombinant) (codes: 19/118 and 19/162) against the 3rd International Standard for Ferritin (Human, Recombinant) (code: 94/572), and three serum commutability samples in an international collaborative study involving 12 laboratories in nine countries. Methods Eleven of the 12 participating laboratories performed Ferritin quantitation using automated assay platforms and one laboratory used a manual ELISA kit. Results There was better overall agreement between all laboratories and between assay methods for the potency of preparation 19/118 than for preparation 19/162. The overall geometric mean potency (from all methods) of the candidate 4th International Standard, 19/118, was 10.5 µg/ampoule, with inter-laboratory variability, expressed as % geometric coefficient of variation (GCV), of 4.7%. Accelerated stability studies have predicted both 19/118 and 19/162 to be very stable for long term storage at −20 °C. Conclusions The candidate 4th International Standard for Ferritin (Human, Recombinant) (19/118) has been shown to be immunologically similar to the 3rd International Standard for Ferritin (Human, Recombinant) (94/572). It was recommended to and accepted by the WHO Expert Committee on Biological Standardization that 19/118 be established as the 4th International Standard for Ferritin (Human, Recombinant) with an assigned potency of 10.5 µg/ampoule and expanded uncertainty limits 10.2–10.8 µg/ampoule (95% confidence; k=2.23).

Calibration of Reference Thromboplastins and Standardisation of the Prothrombin Time Ratio

1983 ◽  
Vol 49 (03) ◽  
pp. 238-244 ◽  
Author(s):  
T B L Kirkwood
Keyword(s):  
Prothrombin Time ◽  
Oral Anticoagulants ◽  
Collaborative Study ◽  
World Health ◽  
Expert Committee ◽  
Calibration Model ◽  
Biological Standardization ◽  
Reference Preparation ◽  
Health Organization ◽  
Practical Implications

SummaryThromboplastins vary in their sensitivity to the haemostatic defect induced by oral anticoagulants. To provide a means of standardising prothrombin time tests, the World Health Organization adopted in 1977 a scheme for calibrating thromboplastins in terms of an International Reference Preparation. Unfortunately, the model on which this scheme was based does not always hold. A revised calibration model has therefore been developed and this has been tested in a recent collaborative study. The revised model, which retains fundamentally the same principle for standardising prothrombin time tests, has proved suitable for calibrating thromboplastins of different species and types and, moreover, has certain statistical advantages over its predecessor. In September 1982, the WHO Expert Committee on Biological Standardization adopted the revised model. This paper explains the nature and rationale of this change and considers its practical implications.

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