scholarly journals The first international standard for human leptin and the first international standard for mouse leptin: comparison of candidate preparations by in vitro bioassays and immunoassays

2001 ◽  
Vol 27 (1) ◽  
pp. 69-76 ◽  
Author(s):  
CJ Robinson ◽  
R Gaines Das ◽  
D Woollacott
Keyword(s):  
Collaborative Study ◽  
World Health ◽  
Expert Committee ◽  
Antibody Preparation ◽  
International Standard ◽  
Mouse Sequence ◽  
Human Sequence ◽  
In Vitro Bioassays ◽  
Human And Mouse

In an international collaborative study, two preparations of human sequence recombinant leptin and two preparations of mouse sequence recombinant leptin were evaluated, using in vitro bioassays and immunoassays, by eight laboratories, in three countries, for their suitability to serve as the international standard (IS) for human and mouse leptin respectively. The bioassays detected the human and mouse leptin with similar potency, while the immunoassays showed a greater response to the leptin of the species against which the antibody preparation had been raised. Comparison of the candidate standards with the various preparations of leptin of the same species currently assayed in the participating laboratories showed that immunoassay measurements cannot be used to predict the biological potency. On the basis of the results reported here, in October 1999 the Expert Committee on Biological Standardization of the World Health Organization established the preparation coded 97/594 as the first IS for human leptin, with an assigned unitage of 4000 IU/ampoule, and the preparation coded 97/626 as the first IS for mouse leptin, with an assigned unitage of 4000 IU/ampoule. The ISs for leptin are distributed by the National Institute for Biological Standards and Control, UK, http://www.nibsc.ac.uk.

The International Standard for Recombinant DNA-derived Erythropoietin: collaborative study of four recombinant DNA-derived erythropoietins and two highly purified human urinary erythropoietins

1992 ◽  
Vol 134 (3) ◽  
pp. 459-484 ◽  
Author(s):  
P. L. Storring ◽  
R. E. Gaines Das
Keyword(s):  
Recombinant Dna ◽  
Collaborative Study ◽  
World Health ◽  
Mouse Spleen ◽  
Expert Committee ◽  
International Standard ◽  
Wide Range ◽  
In Vitro Bioassays

ABSTRACT The International Standard (IS) for Recombinant DNA-Derived (rDNA) Erythropoietin (EPO) (in ampoules coded 87/684) and three other rDNA EPO preparations in ampoules coded 87/690, 87/696 and 88/574 respectively, were compared with two preparations of highly purified human urinary (HU) EPO and the 2nd International Reference Preparation of Human Urinary Erythropoietin for Bioassay (2nd IRP) by 26 laboratories in 11 countries using a wide range of in-vivo and in-vitro bioassays and immunoassays. These EPO preparations were also compared by electrophoresis and isoelectric focusing. Estimates of EPO content in terms of the 2nd IRP by all in-vivo bioassay methods gave combined unweighted geometric means (with 95% fiducial limits) of: 86 (75–99) IU/ampoule for the IS, 81 (70–94) IU/ampoule for 87/690, 58 (48–71) IU/ampoule for 87/696 and 120 (100–143) IU/ampoule for 88/574. Mean estimates of EPO content in terms of the 2nd IRP by in-vitro bioassays (except receptor assays) were larger than, and those by immunoassays were similar to, the mean estimates by in-vivo bioassays. The use of purified rDNA or HU EPO as standards in place of the 2nd IRP reduced the inter-laboratory variability of estimates of purified EPO preparations by in-vivo and in-vitro bioassays and by immunoassays, and reduced the variability of overall mean estimates for each of these preparations between the three types of method. The inter-laboratory variability of immunoassay estimates of human serum EPO was similar whether the 2nd IRP or one of the purified EPOs was used as standard. Significant differences in in-vivo and in-vitro biological, immunological and physicochemical properties were found between these four rDNA EPO preparations and between them and the HU EPO in the two purified preparations and in the 2nd IRP. There were also differences between the immunoreactivities of the two serum EPO samples included in the study, and between them and the immunoreactivities of the purified EPOs. The differences between rDNA EPOs appeared to be related to differences between the cells used for their biosynthesis, but may also be the result of differences in purification methods and of inter-batch variations. Significant differences in assay specificity were observed within each of the three general types of method. The specificity of the in-vivo bioassays was influenced by the route of hormone administration. The specificities of the mouse spleen cell in-vitro bioassays differed from that of the mouse spleen receptor-binding assay. The specificity of one-site immunoassays differed with the type of EPO used as antigen or tracer, with most notable differences between assays using antisera to rDNA and HU EPO. Two-site immunoassays gave significantly lower estimates for serum EPO than one-site immunoassays. On the basis of these results, the World Health Organization (WHO) Expert Committee on Biological Standardization established the preparation in ampoules coded 87/684 as the International Standard for Recombinant DNA-Derived Erythropoietin with an activity of 86 IU Erythropoietin, rDNA-Derived, per ampoule. It also recommended that the WHO keep under consideration the establishment of separate standards for naturally occurring EPO and for rDNA EPO produced in different cell lines. Journal of Endocrinology (1992) 134, 459–484

The second International Standard for Human Pituitary LH: its collaborative study by bioassays and immunoassays

1993 ◽  
Vol 138 (2) ◽  
pp. 345-359 ◽  
Author(s):  
P. L. Storring ◽  
R. E. Gaines Das
Keyword(s):  
World Health ◽  
Expert Committee ◽  
Human Pituitary ◽  
International Standard ◽  
Receptor Assay ◽  
Wide Range ◽  
In Vitro Bioassays ◽  
Second International

ABSTRACT The second International Standard for Human Pituitary LH (in ampoules coded 80/552; 2nd IS) and LH 81/535 (prepared in the same way as the 2nd IS from the same LH preparation) were compared with the International Reference Preparation of Human Pituitary LH for Immunoassay (IRP 68/40) by 19 laboratories in 11 countries, using in-vivo and in-vitro bioassays, a receptor assay and immunoassays. Geometric mean estimates of the LH content of the 2nd IS (with 95% fiducial limits) in terms of IRP 68/40 were: 34·6 (29·1–41·0) IU/ampoule by in-vivo bioassays; 35·8 (27·0–47·4) IU/ampoule by in-vitro bioassays; 58·6 IU/ampoule by one receptor assay; and 36·8 (35·5–38·1) IU/ampoule by immunoassays. The close agreement between the relative activities of the 2nd IS and IRP 68/40 in the wide range of assay systems studied appears to reflect the fact that both standards contain highly purified LH with similar isoform compositions as judged by isoelectric focusing. Estimates of the LH content of LH 81/535 in terms of IRP 68/40 and in terms of the 2nd IS tended to be lower than those for the 2nd IS across all methods, but the differences were not statistically significant. The 2nd IS was found to be as suitable as IRP 68/40 as a standard for the in-vitro bioassay and immunoassay of LH in the two serum samples studied. However, the mean estimates of serum LH in terms of either of these standards were more than 150% larger by in-vitro bioassays than by immunoassays and more than 50% larger by one-site than by two-site immunoassays. This may be a reflection of the differences in the isoform composition of the highly purified LH of the 2nd IS and IRP 68/40 and that of the LH in the sera. The significant intra- and inter-laboratory variability observed in this study for LH estimates, especially by in-vitro bioassays but also by immunoassays, is very pertinent to the interpretation of published comparisons of LH bioactivity and immunoreactivity. Estimates of the LH content of ampoules of the 2nd IS and LH 81/535 kept at elevated temperatures showed that both the 2nd IS and LH 81/535 appeared to be adequately stable under normal storage conditions; the in-vivo and in-vitro bioactivities and receptor binding activities of LH were more sensitive than its immunoreactivities to thermal degradation of the LH structure. On the basis of these results, the World Health Organization Expert Committee on Biological Standardization established the preparation in ampoules coded 80/552 as the second International Standard for Human Pituitary Luteinizing Hormone, and assigned an activity of 35 International Units of human pituitary LH to the contents of each ampoule. Journal of Endocrinology (1993) 138, 345–359

A Collaborative Study to Establish the 2nd International Standard for Tissue Plasminogen Activator (t-PA)

1987 ◽  
Vol 58 (04) ◽  
pp. 1085-1087 ◽  
Author(s):  
P J Gaffney ◽  
A D Curtis
Keyword(s):  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Collaborative Study ◽  
Chinese Hamster ◽  
World Health ◽  
Clot Lysis ◽  
Expert Committee ◽  
Single Chain ◽  
International Standard ◽  
Tissue Plasminogen

SummaryAn international collaborative study involving ten laboratories located in eight different countries was undertaken in order to replace the current International Standard (I.S.) for tissue plasminogen activator (t-PA). Two lyophilised candidate preparations of high purity were assessed in comparison with the current I.S. for t-PA using only a clot lysis assay. One preparation (coded 861670) was purified from a cultured melanoma cell supernatant and was about 98% single chain t-PA while the other preparation (coded 861624) was derived from Chinese hamster ovary (CHO) cells following DNA recombinant procedures and was 75% single chain t-PA.Both candidate preparations of t-PA compared in quite a satisfactory manner with the current I.S. from the viewpoint of the biometrics of parallel line bioassays and both preparations were quite stable for long periods at low temperatures and stable from up to 1 month at temperatures of 20° and 38° C. Both fultil the criteria to serve as a satisfactory Znd International Standard for t-PA. The Fibrinolysis Subcommittee of the International Committee for Thrombosis and Haemostasis recommended the melanoma source t-PA (861670) as the next I.S. in order to maintain continuity with the 1st I.S. which was also a melanomatype preparation. The data from the ten laboratories indicated that each ampoule of the new proposed standard contains 850 international units of t-PA activity by the clot lysis assay. It is planned to present the results of this study to the Expert Committee on Biological Standardization of the World Health Organization at its next meeting and to request that the preparation of t-PA, coded 861670, be established as the 2ndlnternational Standard for t-PA.

A Collaborative Study to Establish an International Standard for Alpha-Thrombin

1992 ◽  
Vol 67 (04) ◽  
pp. 424-427 ◽  
Author(s):  
P J Gaffney ◽  
A B Heath ◽  
J W Fenton II
Keyword(s):  
Elevated Temperatures ◽  
Collaborative Study ◽  
World Health Organisation ◽  
Significant Loss ◽  
Thrombin Inhibitors ◽  
World Health ◽  
Expert Committee ◽  
International Standard ◽  
Assay Procedure ◽  
And Control

SummarySince 1975 an International Standard for Thrombin of low purity has been used. While this standard was stable and of value for calibrating thrombins of unknown potency the need for a pure a-thrombin standard arose both for accurate calibration and for precise measurement of thrombin inhibitors, notably hirudin. An international collaborative study was undertaken to establish the potency and stability of an ampouled pure a-thrombin preparation. A potency of 97.5 international units (95% confidence limits 86.5-98.5) was established for the new a-thrombin standard (89/ 588) using a clotting-assay procedure. Stability data at various elevated temperatures indicated that the standard could be transported and stored with no significant loss of potency.Ampoules of lyophilised a-thrombin (coded 89/588) have been recommended as an International Standard for a-thrombin with an assigned potency of 100 international units per ampoule by the International Society for Thrombosis and Haemostasis (Thrombin and its Inhibitors Sub-Committee) in Barcelona, Spain in July 1990 while the Expert Committee on Biological Standardisation and Control of the World Health Organisation will consider its status at its next meeting in Geneva in 1991.

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.

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.

A Collaborative Study to Establish the 6th International Standard for Factor VIII Concentrate

2001 ◽  
Vol 85 (06) ◽  
pp. 1071-1078 ◽  
Author(s):  
A. B. Heath ◽  
T. W. Barrowcliffe ◽  
S. Raut
Keyword(s):  
Factor Viii ◽  
Collaborative Study ◽  
World Health Organisation ◽  
World Health ◽  
Assay Method ◽  
Expert Committee ◽  
International Standard ◽  
One Stage ◽  
The One ◽  
Good Agreement

SummaryA study was carried out to replace the 5th WHO International Standard (IS) for factor VIII concentrate, because of depletion of stocks. Two candidate concentrates (X and Y) were assayed as potential replacements against the 5th IS for FVIII concentrate, in a collaborative study involving 33 laboratories. Collaborators were asked to use the ISTH/SSC recommendations, including pre-dilution of concentrates in FVIII deficient plasma in their assays. Several laboratories performed more than one assay method and altogether there were 21 sets of assays with the one-stage method, 6 with the two-stage method and 26 with the chromogenic method. There was good agreement between laboratories using each method for the comparison of concentrates X and Y against the 5th IS, but the overall potencies by one-stage and chromogenic methods each differed by approximately 5% from the overall mean, with the chromogenic potency approximately 10% higher than the one-stage. Inter-laboratory agreement was slightly better for concentrate Y than X, and stability studies indicated that Y was more stable than X. After considering all the information, together with comments from participants and from the FVIII/FIX Subcommittee of the ISTH/SSC, candidate Y (NIBSC code [97/616]), was proposed and accepted in October, 1998, by the Expert Committee on Biological Standardisation of the World Health Organisation to be the 6th International Standard for Factor VIII Concentrate with an assigned potency of 8.5 IU/ampoule.

A Collaborative Study to Establish the 5th International Standard for Unfractionated Heparin

2000 ◽  
Vol 84 (12) ◽  
pp. 1017-1022 ◽  
Author(s):  
A. Walker ◽  
Barbara Mulloy ◽  
Trevor Barrowcliffe ◽  
Elaine Gray
Keyword(s):  
Molecular Weight ◽  
Unfractionated Heparin ◽  
Specific Activity ◽  
Collaborative Study ◽  
World Health Organisation ◽  
The Other ◽  
World Health ◽  
Expert Committee ◽  
International Standard ◽  
The World

SummaryTwenty-four laboratories participated in a collaborative study to calibrate a replacement for the 4th International Standard for Unfractionated Heparin (82/502). Both candidate materials A and B, gave excellent intra- and inter-laboratory variations (majority of mean %gcv <10%) when assayed against the 4th International Standard. No major differences of potency estimates were found between methods, although the USP method generally gave lower potencies than the other methods and candidate B gave a greater variation between methods than A. Overall, this study showed that the differences between the candidates are marginal. Based on its narrower molecular weight profile, higher specific activity and slightly lower inter-method variation, candidate A, 97/578, was proposed and accepted in October, 1998, by the Expert Committee on Biological Standardisation of the World Health Organisation to be the 5th International Standard for Unfractionated Heparin with an assigned potency of 2031 IU/ampoule.

Collaborative Study of a Proposed International Standard for Plasma Fibrinogen Measurement

1992 ◽  
Vol 68 (04) ◽  
pp. 428-432 ◽  
Author(s):  
Patrick J Gaffney ◽  
M Y Wong
Keyword(s):  
Collaborative Study ◽  
World Health Organisation ◽  
Plasma Fibrinogen ◽  
World Health ◽  
Expert Committee ◽  
International Standard ◽  
Assay Procedure ◽  
Artery Disease ◽  
And Control ◽  
The Relationship

SummaryThere is increased interest in the relationship between plasma fibrinogen levels and the incidence of coronary artery disease. The National Institute for Biological Standards and Control (UK) has completed a study to establish an International Standard for plasma fibrinogen. This study was conducted using a recommended assay procedure to measure the clottable material present in the proposed lyophilised Standard (coded 89/644). Twenty-two laboratories from nine countries took part in the study and analysis of the data allowed the calibration of 89/644 at 2.4 mg/ml clottable protein. Agreement with this figure was established in two laboratories using three or more different assays for plasma fibrinogen. Degradation studies of the proposed plasma fibrinogen Standard suggested that no loss of clottable protein was observed when the lyophilised material was stored at 20° C for 1 year.The Fibrinogen Sub-Committee of the ISTH (Amsterdam, The Netherlands, June 1991) supported the establishment of 89/644 as an International Standard. This collaborative study will be presented to the Expert Committee on Biological Standardisation of the World Health Organisation at their 1992 session. In the meantime 89/644 will be distributed as the proposed International Standard for plasma fibrinogen measurement containing 2.4 mg/ ml clottable protein.

A Collaborative Study to Establish the 2nd International Standard for Fibrinogen, Plasma

2000 ◽  
Vol 84 (08) ◽  
pp. 258-262 ◽  
Author(s):  
C. M. Whitton ◽  
D. Sands ◽  
P. J. Gaffney ◽  
A. R. Hubbard
Keyword(s):  
Geometric Mean ◽  
Collaborative Study ◽  
World Health Organisation ◽  
World Health ◽  
Expert Committee ◽  
Washington Dc ◽  
International Standard ◽  
Freeze Dried ◽  
Assay Methods ◽  
Almost All

SummaryAn International Collaborative Study involving 12 laboratories in 7 different countries was undertaken in order to replace the 1st International Standard (IS) for Fibrinogen, Plasma (89/644). The candidate replacement standard was the ampouled and freeze-dried residue of solvent/detergent treated plasma and was calibrated as coded duplicates (A and B) versus the 1st IS Fibrinogen, Plasma by automated Clauss assay and by a recommended clot collection (gravimetric) assay. This latter method had been used to calibrate the 1st IS Fibrinogen, Plasma.Comparing the ratios of the potency estimates of sample A to sample B (the coded duplicates), all of the laboratories obtained a ratio within 5% of the expected value of 1.0 by automated Clauss assay, which suggests that the laboratories were able to perform this assay well. Scrutiny of the data obtained from the gravimetric assays revealed that in almost all cases the results were invalid. The results of these assays are included in this report but clearly should be treated with caution and indeed produced significantly lower mean estimates of potency than the other assay methods. The overall geometric mean of all estimates of potency of the proposed 2nd IS Fibrinogen, Plasma (98/612) is 2.19 mg/ampoule by the automated Clauss assay. These data have been presented to the Fibrinogen Sub-Committee of the Standardisation and Scientific Committee (SSC) of the International Society on Thrombosis and Haemostasis (ISTH) (Washington, DC, August 1999), which recommended the establishment of 98/612 as the 2nd IS Fibrinogen, Plasma. This report has been presented to the Expert Committee on Biological Standardisation of the World Health Organisation (ECBS-WHO) at their 1999 session and 98/612 was established as the 2nd IS Fibrinogen, Plasma with a potency of 2.2 mg/ ampoule.

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