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PubMed2001

Collaborative study for the establishment of tetanus vaccine (adsorbed) Third International Standard and European Pharmacopoeia Biological Reference Preparation batch no. 2.

The aim of the present collaborative study was to calibrate two candidate replacement standards for tetanus vaccine for human use in the terms of the Second International Standard (IS) for Tetanus Toxoid, Adsorbed (TEXA-2) using challenge potency assays in guinea pigs and mice and to establish the 3rd IS and the Ph. Eur. BRP batch 2. Two test preparations (coded B and C) were included as candidate replacement for TEXA-2 and Ph. Eur. BRP batch 1 (EBRP-1). This project was run as a joint WHO/Ph. Eur. study. Twenty-seven laboratories representing nineteen countries participated in the study. Twenty-three laboratories performed assays in mice (11 laboratories performed lethal, 11 paralysis, and one serology assays) and fourteen laboratories performed assays in guinea pigs (10 laboratories performed lethal and 4 paralysis assays). Estimates of potency, expressed in ampoule of TEXA-2 per ampoule of candidate replacement standards were two-fold higher in mice than in guinea pigs. However, using the assumed relationship between TEXA-1 and TEXA-2 in mice and guinea pigs (Lyng and Nyerges, 1984), potency estimates for candidate replacement standards (sample coded B and C), in terms of TEXA-1, gives estimates which are similar in both animal models. Stability was assessed within the collaborative study for candidate standard B. On the basis of this collaborative study, the ECBS of WHO has established the candidate material coded B as the Third IS for Tetanus Toxoid, Adsorbed, with an assigned unitage of 469 IU/ampoule, based on its calibration by guinea pig challenge assays (WHO report BS/00.1932). Further studies were organised to assess which of the two candidate standards is most suitable as replacement for EBRP-1. Manufacturers were asked to include candidate B and candidate C in their routine quality control potency assays of tetanus vaccines in order to assess the impact of the use of either preparation on their calibration results. The features and results of this additional phase are described at the end of this report in a separate section entitled "Choice of replacement batch for EBRP-1". Based on these results, at the session in March 2001, the Ph. Eur. Commission adopted candidate B as the Tetanus vaccine (adsorbed) Ph. Eur. BRP Batch 2 with assigned potencies of 469 IU/ampoule for the guinea pig assays and 496 IU/ampoule for the mouse assays.

Animals↗
PubMed1953

The second international standard for penicillin.

In 1950 the Department of Biological Standards, National Institute for Medical Research, London, was authorized by the WHO Expert Committee on Biological Standardization to prepare the Second International Standard for Penicillin. A single batch of specially recrystallized sodium penicillin G was obtained and 11 laboratories in seven different countries were requested to take part in its collaborative assay. 112 assays were carried out, of which 101 were done by cup-plate methods using either Staphylococcus aureus or Bacillus subtilis. The results were subjected to standard methods of analysis, on the basis of which the authors define the Second International Standard for Penicillin as containing 1,670 International Units (IU) per mg, with limits of error (P = 0.05) of 1,666-1,674 IU/mg. The International Unit is therefore redefined as the activity contained in 0.0005988 mg of the Second International Standard for Penicillin.

Biological Assay↗
PubMed1992

Collaborative study of a proposed international standard for plasma fibrinogen measurement.

There 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 degrees 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.

Fibrinogen↗
PubMedDate not supplied

[Internal standard on the basis of the retrovirus vector for the determination of hepatitis C virus in the competitive PCR].

In this work a new type of the internal standard for the competitive RT-PCR is proposed: the RNA standard on the basis of the retrovirus vector. The internal standard has been developed for the qualitative and quantitative determination of hepatitis C virus RNA in patients' blood serum. The proposed internal standard consists of recombinant retrovirus particles in the culture medium of packing cells, containing the modified sequence of hepatitis virus C used for amplification in PCR. The presence of the selective marker--the gene of resistance to puromycin--in the vector makes it possible to determine the titer of virus particles of the standard in experiments of infecting cell cultures. The proposed retrovirus standard is obtained from the culture of packing cells by collecting the cultivation medium used for growing these cells. The virus particles thus obtained are not pathogenic for humans and animals.

Genetic Vectors↗
PubMedDate not supplied

Comparison of various dilutions and solid-phase extraction cleanup on the determination of ephedrine-type alkaloids and internal standard recovery in ephedra botanical raw material and powdered extract.

A study was conducted to determine the effect of 3 dilution levels on the precision of the ephedra alkaloid method when used in conjunction with a solid-phase extraction (SPE) column. For the dilutions studied, SPE column cleanup is necessary because it promotes a greater recovery of the internal standard. However, overall, target precision values were not obtained on the test materials. It was determined that the SPE column is not the cause of the lower recovery in the more concentrated solutions. Significant signal suppression of the internal standard occurs in more concentrated solutions within the mass spectrometer. It is hypothesized that this lack of performance on the part of the SPE column may be linked to its inability to fully clean contaminants from the higher concentration solutions and/or a mass spectrometer overload, which resulted in the internal standard not fully correcting for signal suppression in more concentrated solutions. An internal standard is necessary, especially for accuracy, for the determination of all alkaloids, and only dilute solutions can be accurately analyzed. Due to the sensitivity of the mass spectrometer, it is recommended that the determination of ephedrine alkaloids in dietary supplements and botanicals should be studied using a standard graph at a level 10 x less than the current method. It is also recommended that the SPE column used should be evaluated on its need for the sample dilutions made to fit the newly recommended standard graph.

Alkaloids↗
PubMed1992

A collaborative study to establish an international standard for alpha-thrombin.

Since 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 alpha-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 alpha-thrombin preparation. A potency of 97.5 international units (95% confidence limits 86.5-98.5) was established for the new alpha-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 alpha-thrombin (coded 89/588) have been recommended as an International Standard for alpha-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.

Drug Stability↗
PubMed2006

[Critical comment on nursing expert standards: meeting challenges to improve quality].

The German Network for the Development of Quality in Nursing (DNQP) has published so called nursing "expert standards" on selected nursing issues. These are developed by expert working groups based on the current evidence, subsequently consented, and Implemented exemplarily. The standards aim at securing a generally accepted quality level in nursing. Accordingly, they are already consulted as yardstick for quality inspections and legal judgement identification, making it even more important that they meet recognized criteria. Therefore, members of the nursing section of the German network for evidence-based medicine (DNEbM) critically appraised the standards. Aspects worth being discussed are: definition of the term "expert standard", consideration of internationally recognized criteria for the development ol Suidelines and transparency of methockilogy; professional foundation and differentiation of recommendations, access to the standards, implementation tools, authors' possible conflicts of interest, as well as regular revision of the standards. This statement intents tobe the basis for a discussion on the future development of justified and comprehensible quality levels in nursing in Germany.

Evidence-Based Medicine↗
PubMed2006

[Study on the baseline contents and reference maximum limit standard of heavy metals and harmful element of 23 Chinese herbs in Northern China].

OBJECTIVE: This study was carried out to obtain the baseline contents and establish the reference maximum limits of heavy metals and harmful element in China. METHODS: According as Chinese standard methods of heavy metals and harmful element, 254 Chinese herbs were determined. RESULTS: The contents of lead, cadmium, mercury and arsenic in different Chinese herbs were (1.78 +/- 1.98), (0.17 +/- 0.24), (0.04 +/- 0.06) and (0.72 +/- 0.69)mg/kg, respectively. In the process of establishing the reference maximum limit standards of these harmful substances, the dietary intakes which including the intakes from food, beverage and drinking water were necessarily considered. The intakes including dietary and Chinese herbs of per person per day (and the percent of ADI) of lead, cadmium, mercury and inorganic arsenic were 102.9 microg (45.7%), 21.4 microg (34.0%), 5.7 microg (5.7%) and 81.0 microg (60.5%), respectively. We recommended the reference maximum limit standards of lead, cadmium, mercury and arsenic which in Chinese herbs were 5.0 mg/kg, 0.3 mg/kg, 0.2 mg/kg and 2.0 mg/kg, respectively. CONCLUSION: The survey of baseline level of heavy metals and harmful element was successful. The intakes of these harmful substances were safe to human health. The maximum level standards of lead, cadmium, mercury, arsenic in plant Chinese herbs submitted by our coordinated group have been accepted by Chinese Herbs Codex, 2005 version. This standard is suitable for quality standards in plant Chinese herbs.

Arsenic↗
PubMed1990

[The standard level of IgE RIST and eosinophil counts in 0-year old allergic children according to multiple factor analysis type II].

We specified three standard levels of IgE RIST (10, 20, 60 IU/ml) for the ninety-four (94) allergic clients of 0-year infants, who classified with three groups. Each group was furthermore divided in two groups such as a group under the standard level and a group exceeding the level respectively. Next, using the Multiple Factor Analysis Type II, we examined quantitative analysis that each of three classified groups was influenced on 12 allergic factors of sex, existence and inexistence of wheezing and atopic dermatitis, family history of allergic diseases, eosinophil counts. IgE RAST scores and antibody titers against egg white, milk and soybean, IgE RAST scores to Dermatophagoides farinae, while the we discussed how the standard levels were adequately reacted to the analysis. As a results, strong allergic factors which influenced the three groups commonly were two factors of IgE RAST scores to egg white and D.f. In particular, the factor which influenced the group of 10 IU/ml standard level was eosinophil counts and family history of allergic diseases. Furthermore, the strong factors which influenced the group classified on 60 IU/ml standard outstandingly appeared in IgE RAST scores to soybean, however, we did not find any difference between three groups. On the other hand, when we specified the standard level at 100/mm3, 200/mm3, 400/mm3 in regard to the eosinophil counts under the same method and examined results, we found strong allergic factors which influenced family history of allergic diseases. IgE RAST scores to egg white and soybean. However, the study scarcely recognize any difference between the three groups.

Eosinophils↗
PubMed1990

Standardization of the twinning rate.

There is a great interest in comparing twinning rates. These comparisons can be performed between different time periods for a specific population, between different regions within the same country, and between different populations. However, there are several factors (maternal age, parity, urbanization, etc.) that influence the twinning rate. The most dominant one is maternal age, and because the age distribution of the mother varies, it is necessary to standardize the data to make these comparisons. If we want to compare the twinning rates in different countries, we have to face the problem that the composition of the data from different countries may differ to a great extent. The applicable method is determined by the data of the lowest quality. Often the available data do not allow the traditional (direct and/or indirect) methods of standardization. Under such circumstances other methods have to be used. Earlier, Fellman and Eriksson (1987) proposed and successfully applied a new method. In this article we discuss the standardization problem in more detail. We suggest different methods and apply them to different data on twinning from Australia, Finland, and Baden-Württemberg (West Germany). The new standardization methods give standardized twinning rates similar to the rates obtained by traditional methods. It is noted that, irrespective of standardization method, changes in maternal age alone cannot explain temporal or regional variations in the twinning rate. Other factors that may raise or lower the twinning rate are decreasing parity, sociodemographic changes with increased communication, which causes the breakup of isolates, and deteriorating physical condition of mothers as a result of increased industrialization and urbanization.

Australia↗
PubMed1989

Standardization of apolipoprotein B and A-I measurements.

Apolipoprotein B, the major protein of low-density lipoprotein, and apolipoprotein A-I, the major protein of high-density lipoprotein, can serve as important predictors of atherosclerotic cardiovascular disease. However, these apolipoprotein measurements have not realized their full potential because of inadequate standardization. Purified apolipoprotein A-I of known absolute mass, in lyophilized form, can serve as primary standard for apolipoprotein A-I, and freshly isolated low-density lipoprotein of narrow density range can serve as primary standard for apolipoprotein B. These primary standards can be used to assign target values to secondary reference material and calibrators by reference laboratories using standardized, validated immunoassay procedures. Lyophilized serum can serve as secondary reference material for apolipoprotein A-I. Freshly frozen serum pools should be used as reference material for apolipoprotein B until more practicable materials that do not exhibit matrix interactions are developed. Implementation of proper standardization procedures can lead to significant improvements in apolipoprotein measurements.

Apolipoprotein A-I↗
PubMed1989

[Lysozyme Reference Standard (Control 871) of the National Institute of Hygienic Sciences].

A candidate for the Lysozyme Reference Standard (Control 871) of the National Institute of Hygienic Sciences was prepared. Purity of the standard material examined electrophoretically was more than 99.5%. Lysozyme potency of the standard material was assayed turbidimetrically using dry-cells of Micrococcus luteus as a substrate and compared with that of the Lysozyme Reference Standard (Control 865). Potency of the standard material was in satisfactory agreement with that of the standard and was defined as 1 mg [potency] per mg.

Amino Acids↗
PubMed1988

Standardization for four protein analytes with the Behring Nephelometer.

Owing to the generally higher values observed in the initial establishment of immunoglobulins (Ig) G, A, and M assays with the Behring Nephelometer, we elected to verify five commercial protein calibrators. This initial verification was performed by standardizing the Behring Nephelometer with the World Health Organization (WHO) International Reference Preparation for Human Serum Immunoglobulins G, A, and M. The instrument was also standardized for immunoglobulins and transferrin with use of the Reference Preparation for Serum Proteins (RPSP II). Analytical recoveries of the commercial calibrators varied. Also, assigned protein concentrations in both the WHO and RPSP II preparations made them unacceptable to us as benchmark calibrators for the Behring Nephelometer. Individual proteins (IgG, IgA, IgM, and transferrin) were obtained and primary standards prepared. Both transferrin and IgG were successfully standardized. However, IgA and IgM primary standards lacked 100% antigenicity, requiring removal of nonreactive IgA and IgM or reassignment of the correct value. The problem remains to find appropriate purified materials for IgA and IgM standardization.

Blood Proteins↗
PubMed1986

Is standardization more important than methodology for assay of total protein in cerebrospinal fluid?

Four manual micromethods for protein determination, two turbidimetric (trichloroacetic and sulfosalicylic acid-sodium sulfate) and two colorimetric (Lowry and Coomassie Brilliant Blue--sodium dodecyl sulfate, CBB-SDS) were used to compare the standard curves for total protein (0.30 to 3 g/L) produced with three reference materials: bovine serum albumin, human serum albumin, and diluted human serum. We measured the apparent protein content of a sample of pooled human cerebrospinal fluid by all four methods and with use of all three standards. The only reference material that gave similar results with all four methods was diluted human serum; the CBB-SDS was the only method that gave identical results with all three reference materials. We then measured the protein concentration of 28 individual cerebrospinal fluid samples by the four methods, with diluted human serum as standard. Results by all methods correlated well, but only the sulfosalicylic acid and the CBB-SDS methods gave equivalent results. We conclude that the choice of standard is more important than the method used. However, the CBB-SDS method may be the preferred method because it produced identical standard curves with all three protein standards.

Cerebrospinal Fluid Proteins↗
PubMed1984

Use and significance of reference serum as a secondary standard for electroimmunoassay of apolipoprotein A-I.

This study was designed to show the effect of different primary standards and antisera on the variability of concentrations of apolipoprotein A-I (ApoA-I) in plasma and to document the usefulness of reference sera as a secondary standard in the electroimmunoassay of this apolipoprotein. We compared the reactivities of two separate ApoA-I samples and a preparation of high-density lipoprotein (HDL3) with seven different antisera to ApoA-I. The antisera reacted differently with each of the three standards, as shown by the different slopes of their standard curves. The resulting inconsistencies in the ApoA-I values for unknown plasma samples were shown to be corrected by the use of a reference serum. When ApoA-I analyses were carried out with the reference serum as a standard, all seven antisera gave statistically indistinguishable results for concentrations of plasma ApoA-I. The use of reference sera thus represents the simplest and most convenient means of standardizing the electroimmunoassay for ApoA-I.

Animals↗
PubMed1982

Common units for clotting factors assayed against different standards.

There are no generally accepted units for clotting factors except factor VIII. Results are usually expressed as percentages of the standards used in the assays and standards vary in their potency. Over a six year period, factors V, VII and VIII were measured in over 3000 participants in the Northwick Park Heart Study. Six different standards had to be used. For comparative purposes, all results were expressed in terms of the first standard (71/11). This paper describes how appropriate conversion values were derived. Three different methods were compared. One consisted of the assay of each standard against its replacement. Another was based on the use of a reference plasma spanning the use of two successive standards. The third was a population-based, or epidemiological method using the data from all the participants in the study. This method is based on the assumption that results would be the same in comparable groups of study participants. In order to ensure comparability, personal characteristics which affect clotting factor levels, such as age and degree of obesity, were taken into account. The three methods gave similar results but the population method was, in general, the most satisfactory for factor VIII as well as factors V and VII, and has been adopted for routine use.

Adolescent↗
PubMed1980

Evaluation of perinatal growth. Presentation of combined intra- and extrauterine growth standards for weight, length and head circumference.

The evaluation of perinatal growth requires different approaches depending on the chronological age of the infant. Basically, three periods of perinatal growth are to be distinguished: Intrauterine period: Growth during this period can be estimated by intrauterine growth standards representing fetal growth parameters at birth. Transitional period: Growth during the first 6 to 12 days of life is of transitional nature. It is characterized by large individual variations and does not follow any growth standards. Extrauterine period: After the 6th to 12th day of life growth rates are distinctly higher than those of intrauterine growth. Thus, intrauterine growth standards can not be applied to extrauterine growth, and separate growth standards are required to evaluate growth during this period. In this article combined intra- and extrauterine growth standards for weight, length and head circumference in boys and girls between 28 weeks of gestation and 8 weeks after term are presented. These growth standards are based on the Winterthur Newborn Study (1962-1974) and the Second Zurich Longitudinal Study (1974-1980).

Birth Weight↗
PubMed1981

Effect of outlying standard points on curve fitting in radioimmunoassay.

Outlying points often appear in standard curves for radioimmunoassay. We have examined the effect of outlying standard points on the ability of various automated data-processing routines, and of manual operators, to position a radioimmunoassay standard curve correctly. Manual operators were found to be highly subjective in their handling of a standard curve containing outlying points. Automated methods without outlier rejection capability produced standard curves that were significantly erroneous. In contrast, a data-processing method with automated outlier rejection capability successfully identified outliers, but occasionally rejected valid points--and consequently misplaced the standard curve. Visual identification of outliers is unsatisfactory. Automated identification can be more satisfactory, but some patterns of outliers make it less so. We conclude that any automated data-processing method should contain an outlier rejection facility, but its results should be treated with caution.

Computers↗