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.

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

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.

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.

An international collaborative study on standardization of apolipoproteins A-I and B. Part II. Evaluation of contributions of antisera to among-laboratory variance components.

1987 ◽  
Vol 33 (12) ◽  
pp. 2250-2256 ◽  
Author(s):  
L O Henderson ◽  
W H Hannon ◽  
S J Smith ◽  
G R Cooper
Keyword(s):  
Reference Material ◽  
Total Variation ◽  
Variance Components ◽  
Relative Concentration ◽  
Collaborative Study ◽  
Apo B ◽  
Total Variability ◽  
International Collaborative ◽  
Source Of Error ◽  
International Collaborative Study

Abstract Local antisera (LA) were compared with a common interim reference antiserum (IRA) to examine the antiserum component of the among-laboratory variation in an international collaborative study with 28 laboratories evaluating a candidate international Reference Material (apo-RM) for apolipoproteins A-I (apo A-I) and B (apo B). Measurement of the relative concentration of lyophilized preparations differed by less than 1% for LA and IRA. The percentage of the total variation in measurement of the concentration of apo-RM that was contributed by antisera among laboratories was 5% and 8% for apo A-I and B, respectively. Estimated differences from overall mean concentrations for the five different immuno-methods were greater for apo B (range: +22% to -23.5%) than for apo A-I (range +14% to -14%), but were similar within a method for LA and IRA. The results indicated that antisera are not a major source of error among laboratories and, indeed, are responsible for relatively little of the total variability.

scholarly journals Characterization of Reference Materials for Human Antiserum to Pertussis Antigens by an International Collaborative Study

2008 ◽  
Vol 16 (3) ◽  
pp. 303-311 ◽  
Author(s):  
Dorothy Xing ◽  
Carl Heinz Wirsing von König ◽  
Penny Newland ◽  
Marion Riffelmann ◽  
Bruce D. Meade ◽  
...  
Keyword(s):  
Collaborative Study ◽  
International Standards ◽  
World Health ◽  
Enzyme Linked Immunosorbent Assay ◽  
Expert Committee ◽  
International Standard ◽  
Reference Serum ◽  
International Collaborative ◽  
International Collaborative Study

ABSTRACT Enzyme-linked immunosorbent assay (ELISA) has been widely used to evaluate antibody responses to pertussis vaccination and infection. A common reference serum is essential for the standardization of these assays. However, no internationally recognized reference serum is available. At the request of the Expert Committee on Biological Standardization (ECBS) of the World Health Organization (WHO), a set of four candidate international standards has been prepared. These candidate materials have been assessed for suitability and compared to the widely used U.S. reference pertussis antiserum (human) lot 3, lot 4, and lot 5 by 22 laboratories from 15 countries in an international collaborative study. Laboratories measured immunoglobulin G (IgG) and IgA antibodies to pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin (PRN), and fimbriae (Fim2&3) using their established immunoassays. The results of this study showed each of the four candidates to be suitable as an international standard. With the agreement of the participants, a recommendation has been made to the ECBS that the candidate material coded 06/140 be established as the First International Standard for pertussis antiserum (human), with the following assigned international units (IU): IgG anti-PT, 335 IU/ampoule; IgA anti-PT, 65 IU/ampoule; IgG anti-FHA, 130 IU/ampoule; IgA anti-FHA, 65 IU/ampoule; IgG anti-PRN, 65 IU/ampoule; and IgA anti-PRN, 42 IU/ampoule. No formal units have been proposed for anti-Fim2&3 because most assays used a mixture of fimbrial antigens. In addition, the candidate material coded 06/142 has been proposed as a WHO working preparation for characterization of assay systems.

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.

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.

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