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PubMed2001

Cross-cultural validity and reliability testing of a standard psychiatric assessment instrument without a gold standard.

The objective of this study was to assess the cross-culture validity and reliability of a standard psychiatric assessment instrument without the usual "gold standards." Normally criterion validity testing requires comparison with such a standard--usually another instrument or a professional diagnosis. Instead local informants identified persons with and without "agahinda gakabije" (a locally described grief syndrome) who were then asked if they thought they had this syndrome and also interviewed using the depression section of the Hopkins Symptom Checklist (DHSCL). To assess criterion validity, interviews where respondent and informant agreed on the presence or absence of agahinda gakabije were compared with depression diagnosis using the DHSCL. We also assessed construct validity (using factor analysis), internal reliability (Cronbach's alpha), and test-retest reliability using results from a subsequent community-based survey employing the DHSCL. We found a similar relationship between depression and agahinda gakabije as between depression and grief in western countries, which supports criterion validity. Construct validity and internal reliability were good (Cronbach's alpha = 0.87). Test-retest reliability of a DHSCL-based scale was less adequate (0.67). Although not replacing the usual gold standards for testing criterion validity, this approach may prove useful where these standards are unavailable. As this includes much of the developing world, this could result in more accurate mental health assessments among populations for whom this has hitherto not been possible.

Adult↗

PubMed1980

Standardization of Factor VIII. II. A British Standard for Factor VIII related antigen.

A collaborative study on factor VIII related antigen (VIII R:Ag) has been carried out, involving 11 laboratories in the U.K. Samples of two different freeze-dried plasmas were assayed against participants' own local standards by the Laurell electroimmunoassay method. There was reasonably good agreement on the relative potencies of the two freeze-dried plasmas, but there were considerable differences in the VIII R:Ag content of the plasma pools used as local standards, with values ranging from 83% to 129% of the mean. All participants agreed on the need for a standard for VIII R:Ag, and that the unit be defined by the mean of the local standards. Accordingly, freeze-dried plasma 66/355 was established as the 1st British Standard for factor VIII related antigen, with an assigned potency of 1.05 units per ampoule.

Antigens↗

PubMed2002

Asymptotic standard errors of estimated standard errors in structural equation modelling.

Asymptotic standard errors of the estimated asymptotic standard errors for parameter estimates in structural equation modelling are derived using the delta method with the assumption of multivariate normality for observed variables. The derivation covers the cases with and without restrictions on parameters. The result can be used to derive the asymptotic standard error of the z score (a parameter estimate divided by its estimated standard error), which is frequently substantially different from one. The case of standardized observed variables is dealt with as a typical example with restrictions on parameters. For actual covariance (correlation) structure models, the exploratory factor analysis model with factor rotation and the confirmatory factor analysis model are presented with numerical examples. Simulations are performed to assess the accuracy of our method for normally and non-normally distributed variables.

Behavior↗

PubMed1986

Stevens' power law and time perception: effect of filled intervals, duration of the standard, and number of presentations of the standard.

Subjects estimated the duration of five different time intervals, either filled or unfilled, in relation to one or two standard intervals. Half of the subjects were presented with the standard at the beginning of the experiment only, and half were presented with the standard before every interval. The five estimations were then used to calculate, for each subject, the exponent in Stevens' Power Law which describes the form of the power relationship. The resulting over-all exponent of .91, although nearly linear, was significantly different from 1.0. The data were then analyzed by a 2 X 2 X 2 analysis of variance which showed a significant interaction between presenting the standard either once or before each interval with the duration of the standard.

Female↗

PubMed1958

Third international standard for posterior pituitary; re-named third international standard for oxytocic, vasopressor and antidiuretic substances in 1956.

In October 1955, stocks of the Second International Standard for Posterior Pituitary were running low and the Department of Biological Standards of the National Institute for Medical Research, London, was asked to proceed with the arrangements for an international collaborative assay of material for the Third Standard. A single 142-g batch of posterior-pituitary-lobe powder was obtained and distributed in ampoules, in approximately 30-mg quantities. Samples were sent to 19 laboratories in 10 countries. In all, 185 assays were carried out, 122 for oxytocic activity, 53 for vasopressor activity and 10 for antidiuretic activity.On the basis of the results, which were analysed statistically at the National Institute for Medical Research, it was agreed that the potency of the Third Standard (re-named International Standard for Oxytocic, Vasopressor and Antidiuretic Substances in 1956, in view of the recent synthesis of oxytocin and vasopressin) should be expressed as 2.0 International Units per milligram. The International Unit therefore remains unchanged as 0.5 mg of the dry powder.

Biological Assay↗

PubMed1986

[Standardization of the complement fixation test (CFT) in brucellosis. I. The Polish standard of anti-Brucella abortus serum].

The purpose of this paper was to prepare an indigenous standard of anti-Brucella abortus serum for the complement fixation test (CFT) as a homologue of the secon International Standard of anti-Brucella abortus Serum (ISABS-II), which contains 1000 international units of complement-fixing antibodies in 1 cm3. The indigenous Standard of anti-Brucella Abortus Serum (ISABAS) was prepared in 1975. The material used was the serum of a cow infected with Br.abortus, biotype 1, under natural conditions. The cow was beheaded on the 54th day after abortion. The serum obtained was filtered through a Seitz EK filter and appropriately diluted with normal bovine serum. The preparation was lyophilized in 8500 ampules, each of which contained 1 cm3 of serum. They were filled with nitrogen before closing them. It was shown that ISABAS activity in CFT was approximate to that of ISABS-II. The studies in CVL, Weybridge showed that one ampule contained 1115 international units of complement-fixing antibodies. ISABAS titres in the agglutination test (AT) and antiglobulin test (AGT) were 320+ + and 2560+ + + respectively. Reduction with 2-mercaptoethanol and separation on a column with Sephadex G-200 gel showed that anti-Brucella antibodies occurred in ISABAS mainly in IgG class. ISABAS lyophilizate is characterized by stability of CFT titre, good solubility and a low anticomplementary activity. The average weight of the lyophilizate in an ampule is 79.57 mg, standard deviation - 0.36%. ISABS may serve as the basis of antigen standardization and other elements of indigenous CFT technique in brucellosis.

Animals↗

PubMed1988

Report on skin test standardization. The Committee on Skin Test Standardization of The Netherlands Society of Allergology.

The decision to set up a Committee on Skin Test Standardization was taken in 1985 at the spring meeting of the Netherlands Society of Allergology. The committee's terms of reference were to make recommendations about: (i) the standardization of skin-test techniques; (ii) ensuring the quality of skin-test techniques; (iii) determining whether tests should be carried out using serial dilutions and, if so, under what conditions; (iv) the adaptation of standard series or the use of minimum numbers of allergen extracts with adults and children. This committee cannot be viewed separately from the previously established Committee on the Standardization of Allergen Extracts. The availability of allergen extracts that are as highly standardized as possible is an essential condition for good skin-test diagnostics.

Adult↗

PubMed2001

A review of the DNA standard reference materials developed by the National Institute of Standards and Technology.

The Standard Reference Materials Program at the US National Institute of Standards and Technology (NIST) has three human DNA standard reference materials (SRM 2390, SRM 2391a, and SRM 2392) currently available [1, 2]. Both the DNA profiling SRM 2390 and the polymerase chain reaction (PCR)-based DNA profiling SRM 2391a are intended for use in forensic and paternity identifications, for instructional law enforcement, or for non-clinical research purposes and are not intended for clinical diagnostics. The mitochondrial DNA (mtDNA) SRM 2392 is to provide standardization and quality control when performing PCR and sequencing any segment or the entire 16,569 base pairs that comprise human mitochondrial DNA. SRM 2392 is designed for use by the forensic, medical, and toxicological communities for human identification, disease diagnosis or mutation detection.

DNA↗

PubMed1985

Standardization of factor VIII: establishment and use of secondary standards.

Two secondary standards for use in routine assays of Factor VIII in therapeutic concentrates and in patients, plasmas, respectively, have been established in a multicenter collaborative study. In order to assess the effect of the adoption of these preparations as common Secondary Standards a comparative assay has been performed: one sample of a Factor VIII concentrate of intermediate purity and one plasma sample have been tested in two laboratories for Factor VIII:C activity using as reference, among others, the common working standard. Analysis of the results shows that with the plasma sample the differences of the estimates obtained with any of the references in our two laboratories were not statistically significant (P greater than 0.3), while with the concentrate sample the differences were always statistically significant (P less than 0.005). The study shows that the adoption of common working standards (besides the uniformity in assay method, reagents and basic equipment) is not sufficient to eliminate interlaboratory variation in the measurement of Factor VIII:C.

Antigens↗

PubMed2001

Isotopic analogs as internal standards for quantitative analyses by GC/MS--evaluation of cross-contribution to ions designated for the analyte and the isotopic internal standard.

Isotopic analogs of the analytes are currently preferred internal standards (IS) for quantitative analyses of drugs and their metabolites in biological matrices by GC/MS procedures. Contributions of the analyte and the IS to the intensities of ions designated for the IS and the analyte, respectively--an undesirable phenomenon termed "cross-contribution"--greatly weakens the effectiveness of this approach. The cross-contribution phenomenon has been, in the past, evaluated by a "direct measurement" approach, in which intensities of interested ions were measured in two separate experiments using equal quantities of the analyte and the IS. Alternate procedures that may generate improved results are hereby studied. For the "improved direct measurement" approach, ion intensity data derived from the previously reported direct measurement procedure are first normalized before being used to calculate the extent of cross-contribution. An "internal standard" approach is also developed, in which a set amount of a third compound is incorporated into these two separate experiments, thus allowing corrections of ion intensity data that are imbedded with variations inherent to separate experiments. Finally, a "standard addition" approach, involving a series "addition" of "standards", generates multiple data points; thus, providing a mechanism to validate the resulting cross-contribution data. Secobarbital/(2)H(5)-secobarbital and secobarbital/(13)C(4)-secobarbital pairs are adapted as the exemplar systems for this study.

Gas Chromatography-Mass Spectrometry↗

PubMed1998

Diagnostic value of standardized assays for anti-neutrophil cytoplasmic antibodies in idiopathic systemic vasculitis. EC/BCR Project for ANCA Assay Standardization.

Anti-neutrophil cytoplasmic antibodies (ANCA) are widely used as diagnostic markers for Wegener's granulomatosis (WG), microscopic polyangiitis (MPA), Churg-Strauss syndrome (CSS) and idiopathic rapidly progressive glomerulonephritis (iRPGN). The objective of this study was to evaluate the diagnostic value of ANCA measurement by the indirect immunofluorescence (IIF) test, and by anti-PR3 and anti-MPO ELISA performed in different locations, in patients with idiopathic small vessel vasculitis. Fourteen centers participated in a standardization study of ANCA assays, and entered a total number of 169 newly diagnosed and 189 historical patients with idiopathic systemic vasculitis or iRPGN. Patients were classified according to a pre-defined diagnostic classification system. Results were compared with those of 184 disease controls and 740 healthy controls. The IIF test was performed according to standard methodology; ELISAs had been standardized among the participants in a previous phase of the study. The sensitivities of assays in patients were as follows. The sensitivity in WG was: cANCA 64%, pANCA 21%, anti-PR3 66%, anti-MPO 24%. In MPA the sensitivity was: cANCA 23%, pANCA 58%, anti-PR3 26%, anti-MPO 58%. Sensitivity in iRPGN was: cANCA 36%, pANCA 45%, anti-PR3 50%, anti-MPO 64%. The specificity of assays (related to disease controls) was: cANCA 95%, pANCA 81%, anti-PR3 87%, anti-MPO 91%. When the results of the IIF test were combined with those of the ELISAs (cANCA/anti-PR3 positive, pANCA/anti-MPO positive), the diagnostic specificity increased to 99%. The sensitivity of the combination of cANCA + anti-PR3 or pANCA + anti-MPO for WG, MPA or iRPGN was 73%, 67% and 82%, respectively. From this study we conclude that the value of the IIF test for ANCA detection can be greatly increased by the addition of a well standardized antigen-specific ELISA. In a significant number of patients with idiopathic small vessel vasculitis, however, the ANCA test results (either in IIF or ELISA) are negative.

Adolescent↗

PubMed1983

Rapid inoculum standardization system: a novel device for standardization of inocula in antimicrobial susceptibility testing.

A rapid inoculum standardization system for antimicrobial susceptibility testing without incubation or the conventional turbidity adjustment has been developed. The rapid inoculum standardization system consists of a plastic rod with cross-hatched grooves on one end and a specific nutrient medium in a vial. The crosshatched grooves are designed to pick up and release a known number of viable microorganisms. In use, the end of the rod is touched to five colonies 1 to 2 mm in diameter from a primary agar plate, thus filling the grooves with bacteria. The rod is placed into the vial, and the bacteria are suspended in the medium by agitation with a Vortex Genie Mixer. The resulting suspension contains 5 X 10(7) to 5 X 10(8) CFU/ml for most gram-negative bacilli and gram-positive cocci. Microorganisms such as streptococci that have colonies less than 1 mm in diameter require as many as 10 colonies for an adequate inoculum suspension. Ninety-five commonly encountered bacterial isolates were tested in triplicate by agar plate counts. The resulting overall geometric mean of the agar plate counts was 1.52 X 10(8) CFU/ml for the species tested. We have found that the rapid inoculum standardization system provides a consistent and reproducible method for the standardization of inoculum for antimicrobial susceptibility testing without the incubation period and turbidity adjustment.

Anti-Bacterial Agents↗

PubMed1984

Suitability of the ASM-2 standard test of the National Committee for Clinical Laboratory Standards for evaluation of antimicrobial disk potency.

Standard disks of 25 antimicrobial agents were prepared and tested at three levels of potency (67, 100, and 150% of labeled quantity). The method used was a modification of the approved standard M2-A2 of the National Committee for Clinical Laboratory Standards. Forty-seven susceptibility tests were performed at each potency level by using one to three test organisms. Labeled-potency (100%) disks were within accuracy limits for 85% of the tests and were within daily control limits for 94% of the tests. All susceptibility test data for labeled disks, however, were considered acceptable. The majority (63%) of mean zone diameter data for labeled-content disks were in the upper-one-third percentile of accuracy control limits. A significant proportion (91%) of low-potency disks and considerably fewer (34%) of the high-potency disks were found acceptable when daily control limits were applied. Of most concern are those antimicrobial agents whose low-potency disks approach the lower region of control limits. Zone diameter data from standard disks in the range of potency levels tested suggest that control ranges are excessive for some antimicrobial agent-test organism combinations.

Anti-Bacterial Agents↗

PubMed1992

Quantitative studies of immunofluorescent staining. VII. Quantitative reference standard slide for standardization of fluorescence microscopes.

We evaluated a quantitative reference standard (QRS) slide with 10-microns beads with different concentrations of Coulter Electronics green dye No. 1. Microfluorospectrophotometric readings of the QRS slides provided quantitative comparisons between the sensitivity of the different fluorescence microscopes. The visual comparisons between beads with a range of intensities of fluorescence of Coulter Electronics green dye No. 1 indicated that the end points vary with different optical systems as do the end points in standard indirect immunofluorescent titrations. Fluorescent emission wavelength of QRS slide beads gave the same peak as fluorescein-labeled beads; both differed from the peak of orange beads of an 'Optical Standard' slide. Since shelf life studies show no changes in fluorescence intensity of beads over a period of 27 months or longer, QRS slide beads can afford a device for standardization of fluorescence microscopes used for immunofluorescent tests.

Animals↗

PubMed2001

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.

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.

Animals↗

PubMed1996

The international standard for epidermal growth factor (EGF): comparison of candidate preparations by in vitro bioassays and immunoassays. National Institute for Biological Standards and Control.

Four preparations of recombinant human sequence epidermal growth factor (EGF), two of the full length 53-amino acid chain, and two of the 52-amino acid chain, lacking the carboxyl-terminal arginine, were evaluated, using a variety of in vitro bioassays and immunoassays, by 12 laboratories in seven countries, for their suitability to serve as the international standard for EGF. The study shows that some assay systems appear to discriminate between the full length and the 52-amino acid forms of EGF and that use of a common standard in place of the various in-house standards leads to a substantial decrease in between-laboratory variances in estimates of potency of EGF samples. On the basis of the results reported here, the World Health Organization (WHO) established one of the preparations of the full-length EGF molecule (coded 91/530) as the first international standard (IS) for EGF, with an assigned unitage of 2000 International Units/ampoule, and one of the preparations of EGF(1-52) (coded 91/550) as the first international reference reagent (IRR) for EGF (1-52) with a nominal mass content of 1.75 microg EGF(1-52)/ampoule. The IS for EGF and the IRR for EGF(1-52) may be obtained by writing to NIBSC, PO Box 1193, Potters Bar, EN6 3QH, UK.

Biological Assay↗

PubMed1991

Consistency endangered by FASB-GASB (Financial Accounting Standards Board, Government Accounting Standards Board ) dispute.

The Financial Accounting Foundation's (FAF's) November 1989 decision to uphold the 1984 jurisdictional arrangement between the Financial Accounting Standards Board (FASB) and the Government Accounting Standards Board (GASB) leaves little doubt that the healthcare industry will now be subject to two sets of accounting standards. The FAF's decision created a distinction between the accounting practices of government-owned hospitals and non-hospital governmental entities and their adherence to standards set by FASB, GASB, and the American Institute of Certified Public Accountants. A governmental healthcare organization should carefully determine which accounting rules it follows and remain attentive to further GASB developments.

Accounting↗

PubMed1991

[The effects and properties of sodium nucleinate as a pyrogen working-standard. 9. Pyrogen detection with epinephrine-skin-, dactinomycin- and LAL-tests. The suitability of sodium nucleinate as a pyrogen standard].

Sodium nucleinate (NN) as well as bacterial lipopolysaccharide (LPS) can be detected by epinephrine-skin, dactinomycin and LAL tests. In the quantitative determination of two pyrogen standards for rabbit tests, consisting of NN, a smaller value was found by LAL test for the standard of greatest pyrogenic effect than for that less pyrogenically effective in rabbits. A standard consisting of NN can be used for the pyrogen test in rabbits. But in the future, if necessary a standard consisting of endotoxin will be used, due to its better comparability of results obtained by LAL and rabbit tests.

Animals↗