R E Gaines Das

National Institute for Biological Standards and Control, Potters Bar, England, United Kingdom

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Publications (39)137.2 Total impact

  • P L Storring · R E Gaines Das · J W M Mulders · M Halder
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    ABSTRACT: A pre-validation study was carried out, by six laboratories from six countries, of two physicochemical methods for predicting the in vivo biological potency of recombinant follicle stimulating hormone (follitropin beta), based on quantitative measures of isoform distribution by isoelectric focusing (IEF) and by capillary zone electrophoresis. Each of these methods was used to estimate the predicted bioactivities of four preparations of follitropin beta differing widely in their isoform compositions and specific bioactivities. The results of this study indicate that these methods, and particularly IEF, are transferable between laboratories, and produce results which are sufficiently accurate, precise, and reproducible, for them to be used for predicting the bioactivity of follitropin beta, especially if used with a standard preparation. The performance of these two methods for predicting the bioactivity of other types of follicle stimulating hormone, such as follitropin alfa, would need to be assessed separately, and might involve quantitatively different relationships between the responses measured in the physicochemical method and the bioactivities of preparations estimated by bioassay.
    No preview · Article · Feb 2002 · Developments in biologicals
  • R E Gaines Das
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    ABSTRACT: Underlying the design of any assay and further, interpretation of the results, are multitudes of assumptions and implications, ranging from 'biological' assumptions about the nature of the assay system and its response to the materials assayed to 'statistical' assumptions about the form of the dose-response relationship and the distribution of the response data. As far as possible, assays should be designed and analysis carried out to assess these assumptions. Implications for the individual assay are discussed, since this is where all studies of assays necessarily begin. Consideration is then extended to implications for the combination of data and results of several assays.
    No preview · Article · Feb 2002 · Developments in biologicals
  • B Rafferty · P Maile · P Rigsby · R E Gaines Das · C J Robinson
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    ABSTRACT: Hepatocyte growth factor/scatter factor (HGF/SF) is a potent paracrine growth factor with motogenic, mitogenic and morphogenic activities, and a potential therapeutic role in hepatic and renal disease, as well as diagnostic and prognostic applications. It is synthesised as an inactive, single-chain precursor that is cleaved by serine proteases to give a biologically active, heterodimeric form. To develop World Health Organization (WHO) International Standards (IS) for HGF/SF, candidate preparations of the two forms were assessed in a multicentre study in which they were compared with local standards by bioassay and immunoassay. Among laboratories, there was a wide variation in the estimates of potencies of the candidate standards in terms of in-house reference preparations, but between-assay and within-assay variabilities were low within laboratories. In some assay systems, the precursor and heterodimer showed different responses. Since both molecular forms are widely used in current assay systems, this suggested that a reference preparation was required for each form of the HGF/SF molecule. Accordingly, the Expert Committee on Biological Standardization of WHO established the heterodimeric material (96/564) as the first IS for HGF/SF, human, recombinant, with an assigned unitage of 4000 IU/ampoule and, for the purpose of immunoassay calibration, a nominal HGF/SF content of 4 μg/ampoule. The precursor preparation (96/556) was established as the first IS for HGF/SF (precursor) with an assigned unitage of 2000 IU/ampoule and, for the purpose of immunoassay calibration, a nominal HGF/SF (precursor) content of 4 μg/ampoule. The preparations can be obtained upon written request to the National Institute for Biological Standards and Control (NIBSC, PO Box 1193), by e-mail ([email protected] /* */) or ordered at http://www.nibsc.ac.uk.
    No preview · Article · Jan 2002 · Journal of Immunological Methods
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    P L Storring · R E Gaines Das
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    ABSTRACT: The fourth International Standard for Human Urinary FSH and LH (IS; in ampoules coded 98/704) was compared with the third International Standard for Urinary FSH and LH (IS 71/264) by 10 laboratories in nine countries, using FSH and LH in vivo bioassays. Estimates of the FSH content of the IS by augmented ovarian weight gain assays were homogeneous within each laboratory and over all laboratories. The combined weighted geometric mean estimate of FSH content of the IS (with 95% fiducial limits) in terms of IS 71/264 was 71.9 (69.0-74.9) IU/ampoule. Although estimates by seminal vesicle weight gain (SVW) assays of the relative LH activities of the IS and IS 71/264 were homogeneous within laboratories, estimates were heterogeneous between laboratories. This indicated differences between the spectrum of LH isoforms in the IS and IS 71/264, which were obtained from different manufacturers, and differences between the specificities of SVW assays performed in different laboratories. The differences between the specificities of SVW assays appeared to be related to interactions among mean laboratory seminal vesicle weights, age and genetic strain of rat. The finding of inter-laboratory differences in the specificities of SVW assays is of some significance, as this assay method has been generally adopted by Pharmacopoeias for the control of the LH content of therapeutic products. The combined unweighted geometric mean estimate of LH content of the IS (with 95% fiducial limits) in terms of IS 71/264 by SVW and ovarian ascorbate depletion assays was 70.2 (61.7-80.0) IU/ampoule. Estimates of the FSH and LH content of ampoules of the IS kept at increased temperatures suggested that the IS would be adequately stable under normal storage conditions. On the basis of these results, the World Health Organization Expert Committee on Biological Standardization established the preparation in ampoules coded 98/704 as the fourth International Standard for Human Urinary FSH and LH, and assigned to the contents of each ampoule an activity of 72 International Units of urinary FSH and an activity of 70 International Units of urinary LH.
    Preview · Article · Nov 2001 · Journal of Endocrinology
  • R E Gaines Das · A B Heath · H Martin · D Sesardic
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    ABSTRACT: Ensuring the reliability and precision of assay results requires careful attention to assay design. In this case study we describe validation studies of an in vitro assay for botulinum neurotoxin type A based on its endopeptidase activity towards immobilised synthetic substrate. This assay, in common with many in vitro assays, is sensitive to changes in reagents and assay conditions and is time dependent. In addition, the toxin is not stable in solution. Differences in estimates of potency, resulting from positional factors, which are not significant in individual assays, are shown to be consistent and statistically significant over a longer series of assays. This study emphasizes that assay validation should not be viewed as a single step in assay development but must be considered as a continuing process if assay results are to be reliable and reproducible.
    No preview · Article · Feb 1999 · Developments in biological standardization
  • S. Poole · P. Dawson · R. E. Gaines Das
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    ABSTRACT: On behalf of the World Health Organization, 26 scientists in 13 countries calibrated a candidate international standard for endotoxin and compared it with the Pharmacopoeial standards of the US, Europe and Japan. The study showed that the candidate standard is suitable to serve as the second international standard for endotoxin for all applications, with an assigned unitage of 10,000 international units (IU)/vial, with 1 IU = 1 EU (FDA/USP endotoxin unit). This value maintains continuity of unitage with EC5 (the primary calibrant for the first international standard), EC6 (the current FDA/USP standard), the Japanese Pharmacopoeia Standard and commercial preparations of Limulus lysate. This value is also consistent with calibration of the candidate standard in terms of the European Pharmacopoeia Standard, BRP-2. The establishment of this international standard for endotoxin will permit the global harmonisation of unitage for standards of endotoxin.
    No preview · Article · Jun 1997 · Innate Immunity
  • P L Storring · R J Tiplady · R E Gaines Das · B Rafferty · YG Mistry
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    ABSTRACT: Assays have been developed for the isoforms of erythropoietin (EPO) based on their binding to eight different lectins. These assays were used to compare the isoform compositions of two preparations of human urinary EPO (uEPO) and four preparations of recombinant DNA-derived human EPO (rEPO), which had been shown to differ in their biological and immunological properties and in their isoform composition as judged by isoelectric focusing and electrophoresis. Agarose-bound Ricinus communis agglutinin I (RCA), Erythrina cristagalli agglutinin (ECA), Maackia amurensis leukoagglutinin (MAL), Sambucus nigra agglutinin (SNA), Lycopersicon esculentum agglutinin (LEA), concanavalin A (Con A), Phaseolus vulgaris agglutinin-L4 (L-PHA) and Agaricus bisporus agglutinin (ABA) were used to bind EPO isoforms possessing: N-glycans containing non-sialylated outer Gal beta 1-4GlcNAc (RCA and ECA), NeuAc alpha 2-3Gal beta 1-4GlcNAc (MAL), NeuAc alpha 2-6Gal (SNA), or repeating Gal beta 1-4GlcNAc sequences (LEA); biantennary N-glycans (Con A); tetraantennary and 2,6-branched triantennary N-glycans (L-PHA); and O-glycans containing NeuAc alpha 2-6GalNAc (SNA) and Gal beta 1-3GalNAc (ABA). Free EPO was measured by mouse spleen cell bioassay or immunoassay. Estimates from most lectin-binding assays were reproducible between assays and batches of lectin-agarose, although batches of MAL- and ABA-agarose, and to a lesser extent LEA-agarose, differed in their EPO-binding. Lectin-binding assays showed differences between the isoform compositions of all EPOs, including the two Chinese hamster ovary cell-derived rEPOs, with RCA- and ECA-binding assays being the most discriminating. Lectin-binding estimates provided evidence that uEPO differs from these rEPOs in its lower content of isoforms with biantennary N-glycans and higher content of those with multiantennary N-glycans, and in its lower content of isoforms with N-glycans possessing repeating Gal beta 1-4GlcNAc sequences and of those with O-glycans containing Gal beta 1-3GalNAc. Lectin-binding estimates also indicated that, contrary to some reports, uEPO possesses Gal beta 1-3GalNAc-containing O-glycans but not NeuAc alpha 2-6GalNAc-containing O-glycans or NeuAc alpha 2-6Gal-containing N-glycans. Most groups of lectin-bound EPO isoforms did not differ in their relative bioactivities and immunoreactivities. However, estimates for ABA-bound EPO isoforms suggested that O-glycans might influence the bioactivity of EPO differently to its immunoreactivity. Furthermore, the bioactivities of some ECA-bound EPO isoforms were higher, and those of some of the MAL-bound EPO isoforms lower, than their immunoreactivities, consistent with the reported enhancement of EPO in vitro bioactivity by desialylation.
    No preview · Article · Oct 1996 · Journal of Endocrinology
  • M P Rose · R E Gaines Das
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    ABSTRACT: The First International Standard for Inhibin, Human Recombinant, (ISI), a lyophilized preparation of rDNA-derived human 32 kDa Inhibin A in ampoules coded 91/624, was evaluated by international collaborative study for its suitability to serve as an International Standard. This study, which involved 15 laboratories in nine countries, included a variety of in vitro bioassays and immunoassays. The ISI was compared with two other lyophilized preparations of human recombinant inhibin, the International Standard for Porcine inhibin (ISP) and preparations of human follicular fluid inhibin. Predicted loss of activity based on estimates of potency of contents of ampoules which had been stored under conditions of accelerated thermal degradation indicated that the ISI has satisfactory stability. On the basis of the results of this study, the ISI was deemed suitable to serve as a standard for in vitro bioassays and immunoassays and was established by the Expert Committee on Biological Standardization of the World Health Organization as the First International Standard for inhibin, recombinant human, with an assigned unitage of 150,000 International Units per ampoule. This unitage maintains an approximate continuity of units with the ISP.
    No preview · Article · Apr 1996 · Biologicals
  • R.E. Gaines Das · A Meager
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    ABSTRACT: Biological assays for tumour necrosis factor (TNF) are primarily based on its cytotoxic effect in tumour cell lines, and many of these bioassays are carried out using microtitre plates. Many immunoassays for TNF also routinely use microtitre plates. Data from an international collaborative study, carried out by twenty participants in nine countries, each of whom evaluated seven different ampouled preparations of human tumour necrosis factor alpha (hTNF-alpha), one ampouled preparation of human tumour necrosis beta (hTNF-beta) and one ampouled preparation of mouse tumour necrosis factor alpha (mTNF-alpha) provided a unique opportunity for a broadly based evaluation and comparison of assay designs and results. The results of this evaluation can be applied to a wide range of in vitro assays based on cell cytotoxicity or proliferation. The results of this evaluation indicated that although it is difficult to achieve control of all factors which contribute to the variability of assay responses, assays may be designed to provide measures of the variation due to some factors and to improve reliability of estimates of relative potency.
    No preview · Article · Jan 1996 · Biologicals
  • P L Storring · R E Gaines Das
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    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.(ABSTRACT TRUNCATED AT 250 WORDS)
    No preview · Article · Sep 1993 · Journal of Endocrinology
  • R E Gaines Das · S Poole
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    ABSTRACT: Three ampouled preparations of interleukin-6 (IL-6) were evaluated by 12 laboratories in seven countries for their suitability to serve as the international standard of IL-6. The preparations were assayed using in vitro bioassays and immunoassays. On the basis of the results reported here, with the agreement of the participants in the study and with the authorization of the Expert Committee on Biological Standardization (ECBS) of the World Health Organization (WHO) one of the preparations (coded 89/548) was established as the international standard of IL-6.
    No preview · Article · May 1993 · Journal of Immunological Methods
  • D Sesardic · M.Y. Wong · R E Gaines Das · M J Corbel
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    ABSTRACT: The First International Standard (IS) for Antitetanus Immunoglobulin, Human (coded 26/488) was established by the WHO Expert Committee on Biological Standardization in October 1992 on the basis of an extensive pharmaceutical evaluation and an international collaborative study. Fifteen laboratories from 15 countries performed the toxin neutralization assay in vivo in the study. Twelve laboratories also performed an alternative in vitro assay. The new International Standard is a purified human immunoglobulin containing antibodies which are able to neutralize tetanus toxin. This new standard replaces the Second International Standard for Tetanus antitoxin, Equine, for testing of human antitetanus immunoglobulin preparations used clinically as well as for titration of human serum samples for tetanus antitoxin. The new International Standard was assigned a potency of 120 International Units (IU) of Tetanus Antitoxin per ampoule on the basis of its calibration in terms of the International Unit defined by the Second International Standard for Tetanus Antitoxin, Equine by toxin neutralization assay in vivo. The same preparation was also established as the first European Pharmacopoeia Standard for Antitetanus Immunoglobulin, Human by the European Pharmacopoeia Commission, Biological Standardization Programme in March 1993.
    No preview · Article · Apr 1993 · Biologicals
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    R E Gaines Das · M Rose · J M Zanelli
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    ABSTRACT: A lyophilized preparation of inhibin from porcine ovarian follicular fluid, ampoule code 86/690, was made internationally available as a research standard for in vitro bioassays in 1987. A study involving ten participants in eight countries assessed the stability and suitability of this research standard to serve as an international standard. Each of the participants used in vitro assays, the majority of which depended upon the inhibition of release of follicle-stimulating hormone from dispersed rat anterior pituitary cells. The research standard 86/690 was compared with coded ampoules of 86/690 stored under conditions of accelerated thermal degradation and with inhibins from different species. Intra- and interlaboratory variation for estimates of potency of a coded duplicate ampoule of the research standard provided the basis for comparisons of non-identical inhibins, but the fourfold variability of potency estimates for identical ampoules was such that no conclusions about the differences seen for non-identical inhibins could be made. Predictions of stability from consensus estimates of potency of ampoules that have undergone accelerated thermal degradation indicated that the research standard had satisfactory stability. On the basis of this study, the research standard 86/690 was deemed sufficiently stable and suitable to serve as a standard for in vitro bioassays and was established by the World Health Organization Expert Committee on Biological Standardization as the First International Standard for Porcine Inhibin. The possible presence, in biological extracts (standard or sample), of other bioactive proteins, such as activin and follistatin, complicates the quantitative interpretation of bioassay data. A standard of highly purified human inhibin is now required as a standard for immunoassays used for clinical research purposes; sufficient quantities of recombinant human inhibins have recently been donated for ampouling and evaluation by bio- and immunoassay in the subsequent phase of the standardization of inhibins.
    Preview · Article · Dec 1992 · J Reprod Fertil
  • P L Storring · R E Gaines Das
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    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.(ABSTRACT TRUNCATED AT 400 WORDS)
    No preview · Article · Oct 1992 · Journal of Endocrinology
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    ABSTRACT: 1. The hyperalgesic effects of interleukin-1 beta (IL-1 beta) and prostaglandin E2 (PGE2) were measured in rats. 2. Hyperalgesic responses to IL-1 beta were inhibited in a dose-dependent manner by alpha-melanocyte stimulating hormone (alpha-MSH)-related peptides with the following order of potency: [N1(4),D-Phe7]alpha-MSH greater than alpha-MSH greater than Lys-D-Pro-Val greater than Lys-Pro-Val greater than Lys-D-Pro-Thr greater than D-Lys-Pro-Thr. 3. Hyperalgesic responses to PGE2 were not inhibited by Lys-D-Pro-Thr and D-Lys-Pro-Thr but were inhibited in a dose-dependent manner by the other peptides with the same order of potency as against IL-1 beta. 4. The potencies of [N1(4), D-Phe7]alpha-MSH and alpha-MSH were greatly diminished by deletion of their C-terminal tripeptide, Lys11-Pro-Val13. 5. Nor-binaltorphimine (Nor-BNI) largely reversed the analgesic effects of alpha-MSH, [N1(4), D-Phe7]alpha-MSH, Lys-Pro-Val and Lys-D-Pro-Val indicating that kappa-opioid receptors mediated the analgesic activity of these peptides. 6. Nor-BNI did not antagonize the inhibition by Lys-D-Pro-Thr and D-Lys-Pro-Thr of IL-1 beta evoked hyperalgesia indicating that these peptides were not acting via kappa-opioid receptors.
    Preview · Article · Jul 1992 · British Journal of Pharmacology
  • S Poole · R E Gaines Das
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    ABSTRACT: Three ampouled preparations of interleukin-1 alpha (IL-1 alpha) and three ampouled preparations of interleukin-1 beta (IL-1 beta) were evaluated by 13 laboratories in six countries for their suitability to serve as international standards for these materials. The preparation were assayed in in vitro and in vivo bioassays, radioreceptor assays and immunoassays. On the basis of the results reported here, with the agreement of participants in the study and with the authorization of the Expert Committee on Biological Standardization (ECBS) of the World Health Organization (WHO), one of the preparations of IL-1 alpha and one of the preparations of IL-1 beta were established as international standards for these materials. Further, since the relative activities of IL-1 alpha and IL-1 beta were dependent upon the assay systems used, it was decided that reference should be made to units of IL-1 alpha activity or IL-1 beta activity rather than to IL-1 activity.
    No preview · Article · Sep 1991 · Journal of Immunological Methods
  • S. Poole · R.E. Gaines Das
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    ABSTRACT: Three ampouled preparations of interleukin-1α (IL-1α) and three ampouled preparations of interleukin-1β (IL-1β) were evaluated by 13 laboratories in six countries for their suitability to serve as international standards for these materials. The preparations were assayed in in vitro and in vivo bioassays, radioreceptor assays and immunoassays. On the basis of the results reported here, with the agreement of participants in the study and with the authorization of the Expert Committee on Biological Standardization (ECBS) of the World Health Organization (WHO), one of the preparations of IL-1α and one of the preparations of IL-1β were established as international standards for three materials. Further, since the relative activities of IL-1α and IL-1β were dependent upon the assay systems used, it was decided that reference should be made to units of IL-1α activity or IL-1β activity rather than to IL-1 activity.
    No preview · Article · Aug 1991 · Journal of Immunological Methods
  • A F Bristow · R P Gooding · R. E. Gaines Das
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    ABSTRACT: Three preparations of recombinant DNA-derived insulin-like growth factor-I (IGF-I) were obtained, prepared in ampoules coded 86/522, 86/720 or 87/518, and evaluated as candidate International Reference Reagents in an international collaborative study (nine laboratories in four countries) in response to a request by the World Health Organization (WHO). Immunoassay dose-response curves for each of the three preparations did not in general differ significantly from those of local standards or from those of ampouled preparations of serum-derived IGF-I which were included in the study. The estimates of ampoule contents in terms of local standards showed considerable heterogeneity; the between-laboratory variability of estimates in terms of local standards was ten times greater than the inherent variability of estimates from these systems as estimated from comparisons of coded duplicates. Bioassay data were limited, and those available were inconsistent with immunoassay data. Of the three preparations, ampoules coded 86/720 were derived from an IGF-I preparation that was heterogeneous by high-performance liquid chromatography, and stability data for the preparation 86/522 were anomalous. As a result, the ampouled preparation coded 87/518 has been established by WHO as the International Reference Reagent for IGF-I for immunoassay, with an assigned ampoule content of 3.1 micrograms/ampoule, and is available from the National Institute for Biological Standards and Control.
    No preview · Article · Jun 1990 · Journal of Endocrinology
  • P L Storring · R E Gaines Das
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    ABSTRACT: The International Standard for Pituitary FSH (IS; in ampoules coded 83/575) was assayed in terms of the Second International Reference Preparation of Human Pituitary FSH and LH for Bioassay (IRP 78/549) by 27 laboratories in 13 countries using bioassays, receptor assays and immunoassays. Estimates of the FSH content of the IS by in-vivo bioassay were homogeneous both within and between laboratories and gave a combined geometric mean (with 95% fiducial limits) of 79.9 (74.6-85.4) i.u./ampoule. Estimates by different in-vitro bioassays and receptor assays were also homogeneous between assays and laboratories, and gave a combined geometric mean (with 95% fiducial limits) of 31.2 (28.8-33.9) i.u./ampoule. However, estimates by the 19 different immunoassay systems were heterogeneous and varied between 5 and 31 i.u./ampoule. The material in ampoules coded 83/575 was established by the World Health Organization as the International Standard for Pituitary FSH. It was assigned a unitage of 80 i.u./ampoule on the basis of its calibration by in-vivo bioassay, because this assay best identifies and defines the hormone. However, the introduction of the new IS will necessitate the recalibration of immunoassay kits. FSH 84/530, prepared in the same way as the IS from the same FSH preparation, did not differ significantly from the IS in any of the assay systems studied and appeared to be equally suitable as a standard. Four highly purified preparations of human FSH (FSH A-D), differing in their isoform compositions and in their in-vivo: in-vitro bioactivity ratios, were also studied.(ABSTRACT TRUNCATED AT 250 WORDS)
    No preview · Article · Dec 1989 · Journal of Endocrinology
  • D Schulster · R E Gaines Das · S L Jeffcoate
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    ABSTRACT: Three ampouled preparations of purified human prolactin were assessed by 20 laboratories in eight countries for their suitability to serve as International Standards for the estimation of human prolactin in serum. Bioassays (pigeon crop sac assays and NB2 cell assays) were carried out in two laboratories, radioreceptor assays by one laboratory and radioimmunoassays by 17 laboratories. By physicochemical analysis the preparations appeared similar. Each preparation contained small amounts of contaminants and/or prolactin variants. No major differences among the three preparations were detected by immunoassay although, in one radioreceptor assay system, one of the preparations was found to differ from the other two. On the basis of all the available information, the Expert Committee on Biological Standardization of the World Health Organization (ECBS) in 1986 established the preparation in ampoules coded 83/562 as the Second International Standard for Prolactin and in October 1988 established the preparation in ampoules coded 84/500 as the Third International Standard for Prolactin. A value of 0.053 IU (53 mIU) prolactin activity/ampoule was assigned to both the Second and Third IS on the basis that this unitage would, insofar as possible, maintain continuity of the IU defined by the First International Reference Preparation of Prolactin, human, for Immunoassay (coded 75/504).
    No preview · Article · May 1989 · Journal of Endocrinology