International Collaborative Study for the Establishment of the Second International Reference Preparation of Plasmin

1983 ◽  
Vol 50 (03) ◽  
pp. 645-649 ◽  
Author(s):  
P J Gaffney ◽  
M V Mussett
Keyword(s):  
Collaborative Study ◽  
World Health ◽  
Expert Committee ◽  
Glycerol Solution ◽  
International Reference ◽  
Freeze Dried ◽  
Reference Preparation ◽  
International Collaborative ◽  
International Collaborative Study ◽  
Second International

SummaryAn international collaborative study involving seven laboratories was undertaken to assess the suitability of a freeze- dried preparation of human plasmin to replace the current International Reference Preparation (IRP) for plasmin. Chromogenic and fibrinolytic assays were used by all participating laboratories to assess the potencies of the Proposed International Reference Preparation (PIRP) and two other freeze-dried plasmins, one of human and one of porcine originThe data suggest that the PIRP is a more suitable standard for plasmin than the IRP in that the former binds to fibrin whereas only 50% of the latter binds. The PIRP compared well to other plasmin preparations and the potency assays were independent of the assay procedure and substrate used. Degradation studies indicated that the PIRP was far more stable than the glycerol solution of the IRP, surviving for 12 months at 37° C with no significant loss in either amidolytic or fibrinolytic activity. The International Committee for Thrombosis and Haemostasis (Bergamo, 1982) 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 second International Reference Preparation for Plasmin with a defined potency of 10 International Units of Plasmin 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 collaborative study on standardization of apolipoproteins A-I and B. Part I. Evaluation of a lyophilized candidate reference and calibration material.

1987 ◽  
Vol 33 (12) ◽  
pp. 2240-2249 ◽  
Author(s):  
S J Smith ◽  
G R Cooper ◽  
L O Henderson ◽  
W H Hannon
Keyword(s):  
Reference Material ◽  
Collaborative Study ◽  
Study Data ◽  
World Health ◽  
Expert Committee ◽  
Response Curves ◽  
Apo B ◽  
Reference Preparation ◽  
International Collaborative ◽  
International Collaborative Study

Abstract We evaluated a lyophilized serum preparation for use as a candidate Reference Material for apolipoproteins (apo) A-I and B. An international collaborative study was conducted with 28 participating laboratories, selected on the basis of participation and demonstrated expertise in a 1983 survey of apolipoproteins A-I and B. The analytical suitability of the material was established by confirming linearity of its dose-response curves over a desired concentration range and demonstrating that its response curves paralleled those for fresh sera. Differences in dilution-adjusted mass units ascribable to the five analytical methods used by the various laboratories constituted only 1% of the total variation for apo A-I, but 32% for apo B. The dominant source of error, however, for both apo A-I and B was the variability among laboratories, rather than variability among methods and antisera. The assigned consensus mass-concentration units based on study data are 1.124 g/L for apo A-I, 0.589 g/L for apo B. For these estimates the coefficients of variation were 13% and 27%, respectively. These findings on the proposed Reference Material meet the requirements suggested by the World Health Organization's Expert Committee on Biological Standards for a candidate WHO Reference Preparation.

An International Collaborative Study Establishing a Reference Preparation for Antithrombin III

1980 ◽  
Vol 43 (01) ◽  
pp. 010-015 ◽  
Author(s):  
T B L Kirkwood ◽  
T W Barroweliffe ◽  
D P Thomas
Keyword(s):  
Antithrombin Iii ◽  
Collaborative Study ◽  
World Health ◽  
Normal Plasma ◽  
Freeze Dried ◽  
At Iii ◽  
Reference Preparation ◽  
International Collaborative ◽  
Suitable Reference ◽  
International Collaborative Study

SummaryAn international collaborative study involving 12 laboratories in 7 countries was carried out to establish a suitable reference preparation of antithrombin III (At III). The amount of At III present in two purified preparations, a freeze-dried normal plasma and local normal plasma pools was measured by clotting, immunological, and amidolytic assays. 120 assays were submitted of which 105 were accepted as valid for inclusion in subsequent analyses. Less laboratory to laboratory variation was found when At III was assayed in freeze-dried normal plasma, as compared to purified preparations of At III, and there was also less method to method variation when At III was measured in freeze-dried plasma. When measured as heparin co-factor activity, the two purified preparations contained only about half the level of At III found by immunoassay or progressive At III clotting assays. In contrast, the use of freeze-dried plasma provided results which showed excellent agreement between the various laboratories by all assays; accordingly, this material has been established by the World Health Organization as the International Reference Preparation for At III, with an assigned potency of 0.9 i. u. per ml.

International Collaborative Study for the Calibration of a Proposed Reference Preparation for Thromboplastin, Human Recombinant, Plain

1998 ◽  
Vol 79 (02) ◽  
pp. 439-443 ◽  
Author(s):  
Veena Chantarangkul ◽  
Barbara Negri ◽  
Marigrazia Clerici ◽  
Pier Mannuccio Mannucci ◽  
Armando Tripodi
Keyword(s):  
Collaborative Study ◽  
Mean Value ◽  
World Health ◽  
Practical Reasons ◽  
Calibration Model ◽  
Average Value ◽  
Reference Preparation ◽  
International Collaborative ◽  
Health Organization ◽  
International Collaborative Study

SummaryStocks of the International Reference Preparation (IRP) for thromboplastin, human, plain, coded BCT/253 and held by the World Health Organization (WHO) are nearly exhausted and must be replaced. For practical reasons the choice of the replacement candidate was restricted to two available human recombinant preparations which were coded as X/95 and Y/95 and calibrated in an international collaborative study involving 19 laboratories from Europe, Australia, Canada and Argentina. To minimize the differences between routes of calibration, the two candidates were calibrated against the existing WHO-IRP from human, rabbit and bovine origin and the final ISI was the resultant average value. On the basis of predefined criteria (i.e., within- and between-laboratory precision of the calibration and the conformity to the calibration model), X/95 was the preferred candidate. The assigned ISI (SE of the mean) value is 0.940 (0.0060) and the interlaboratory coefficient of variation 4.7%.

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.

INTERNATIONAL REFERENCE PREPARATION OF HUMAN PROLACTIN FOR IMMUNOASSAY: DEFINITION OF THE INTERNATIONAL UNIT, REPORT OF A COLLABORATIVE STUDY AND COMPARISON OF ESTIMATES OF HUMAN PROLACTIN MADE IN VARIOUS LABORATORIES

1979 ◽  
Vol 80 (1) ◽  
pp. 157-168 ◽  
Author(s):  
ROSE E. GAINES DAS ◽  
P. MARY COTES
Keyword(s):  
Human Plasma ◽  
Collaborative Study ◽  
World Health ◽  
Expert Committee ◽  
International Reference ◽  
Two Samples ◽  
Human Prolactin ◽  
Reference Preparation ◽  
Prolactin Content ◽  
Made In

As authorized by the World Health Organization 29th Expert Committee on Biological Standardization, the preparation of human prolactin in ampoules coded 75/504 has been established as the International Reference Preparation (IRP) of human prolactin for immunoassay. From the results of a collaborative study, to which 15 laboratories in nine countries contributed, with the agreement of the participants, the content of each ampoule is defined as 0·650 International Units (i.u.; 650 mi.u.) immunoassay. The results of this collaborative study show that the IRP is adequately stable and suitable for use as a standard for the determination of prolactin in human plasma and serum. Estimates of the prolactin content of human plasma and serum made in the various laboratories have been compared and show good agreement in ranking order, but only fair agreement in the numerical value of the estimates. Numerical agreement is poor between estimates of the human prolactin content of two samples identical except for coding; this shows the difficulty in achieving continuity of estimates when any laboratory calibrates a replacement standard.

Establishment of the second international standards for porcine and human calcitonins: report of the international collaborative study

1993 ◽  
Vol 128 (5) ◽  
pp. 443-450 ◽  
Author(s):  
Joan M Zanelli ◽  
Rose E Gaines-Das ◽  
P Corran
Keyword(s):  
World Health Organization ◽  
Collaborative Study ◽  
International Standards ◽  
World Health ◽  
International Reference ◽  
International Standard ◽  
Reference Preparation ◽  
Health Organization ◽  
International Collaborative Study

The biological potency of calcitonins in clinical use in long-term treatment of Paget's disease of bone and, increasingly, in osteoporosis is usually expressed in international units defined by the relevant World Health Organization international reference preparation. The international reference preparations for porcine and human calcitonins were ampouled in 1970 and stocks are now exhausted. Replacement standards were ampouled in 1989 and have been evaluated and calibrated by an international collaborative study comprising 16 laboratories in 12 countries. Evaluations included high-performance liquid chromatography and in vitro bioassay; calibration of each new ampouled preparation in terms of its international reference preparation was by in vivo rat hypocalcaemia bioassay. On the basis of the results of the study and with the agreement of the participants, replacement standards were established by the Expert Committee on Biological Standardization of the World Health Organization in 1991: the international standard for porcine calcitonin (ampoule code 89/540), with an assigned potency of 0.8 international units per ampoule, and the international standard for human calcitonin, with an assigned potency of 17.5 international units per ampoule. Both international standards appeared to be sufficiently stable to serve as the international standards for in vivo biological assays. Comparison of the two species of calcitonin in the same hypocalcaemia assay showed that they were approximately equipotent when the doses were given intravenously but that the human peptide was four- to sixfold more potent than porcine calcitonin when doses were given subcutaneously, emphasizing the need to compare "like with like".

International Collaborative Study on the Assay of Commercially Available High and Low Molecular Weight Urokinases

1981 ◽  
Vol 45 (01) ◽  
pp. 034-037 ◽  
Author(s):  
P J Gaffney ◽  
S M Tydeman ◽  
T B L Kirkwood ◽  
D Aronson ◽  
G Murano
Keyword(s):  
Molecular Weight ◽  
Collaborative Study ◽  
Relative Potency ◽  
Low Molecular Weight ◽  
International Reference ◽  
Molecular Weights ◽  
Reference Preparation ◽  
International Collaborative ◽  
International Collaborative Study

SummaryUrokinases of different molecular weights are now commercially available. An international collaborative study (eight laboratories) has been conducted to investigate the effect of type and concentration of plasminogen on the assay of two different urokinase preparations against the International Reference Preparation (IRP). Considerable inter-laboratory variation in relative potency estimation was found, and a small effect of plasminogen concentration, independent of type, was apparent.

The International Reference Preparation of Calcitonin, Human, for Bioassay: Assessment of material and definition of the International Unit

1980 ◽  
Vol 93 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Rose E. Gaines Das ◽  
Joan M. Zanelli
Keyword(s):  
Collaborative Study ◽  
World Health ◽  
Human Calcitonin ◽  
International Unit ◽  
International Reference ◽  
Reference Preparation ◽  
Definition Of ◽  
Health Organization ◽  
International Collaborative Study

Abstract. An international reference material is required for bioassays of preparations of synthetic human calcitonin for administration to man and for use in immunoassays. A preparation of synthetic human calcitonin in ampoules coded 70/234 (previously widely used as the MRC Research Standard) has been examined in an international collaborative study involving 7 laboratories in 6 countries. The results of 34 in vivo bioassays with two other preparations of synthetic human calcitonin showed that this preparation was suitable to serve as a standard. With the agreement of the participants in the collaborative study, the batch of ampoules, code 70/234, was established in 1978 by the World Health Organization as the International Reference Preparation of Calcitonin, Human, for Bioassay. The International Unit of human calcitonin was defined as the activity contained in one ampoule of this preparation, thus maintaining continuity of the unit of the research standard.

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