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At least 325 records · Page 18Linked to original sources
PubMed1994

Selection of European Union standard reference sera for use in the serological diagnosis of infectious bovine rhinotracheitis.

A study, consisting of three trials, was undertaken in order to find standard reference sera for use in serological diagnostic procedures for infectious bovine rhinotracheitis (IBR) in the European Union (EU). A total of forty-nine laboratories participated in the trials, in which panels of positive, weak positive, and negative candidate sera were tested blind by neutralisation, indirect and blocking enzyme-linked immunosorbent assay, indirect immunofluorescence and passive haemagglutination. A serum which scored positive in all tests in all laboratories was selected as a strong positive standard serum. The chosen negative standard serum gave negative results in virtually all tests. A 1/36 dilution of a positive serum was chosen as the weak positive standard serum and only very sensitive techniques were able to score it positive. Three EU reference sera are now available for the standardisation of serological tests for IBR.

Animals↗
PubMed2004

Assignment of weight-based antibody units for 13 serotypes to a human antipneumococcal standard reference serum, lot 89-S(f).

Weight-based immunoglobulin G (IgG), IgM, IgA, and total Ig antibody assignments were made to human antipneumococcal standard reference serum lot 89-S, also known as lot 89-SF, for Streptococcus pneumoniae capsular polysaccharide (PnPs) serotypes 2, 6A, 8, 9N, 10A, 11A, 12F, 15B, 19A, 17F, 20, 22F, and 33F, as well as for C-polysaccharide (C-Ps), extending the standard's usefulness for pneumococcal vaccine evaluation beyond the original serotype 1, 3, 4, 5, 6B, 7F, 9V, 14, 18C, 19F, and 23F assignments (S. A. Quataert, C. S. Kirch, L. J. Quackenbush Wiedl, D. C. Phipps, S. Strohmeyer, C. O. Cimino, J. Skuse, and D. V. Madore, Clin. Diagn. Lab. Immunol. 2:590-597, 1995). The additional 14 assignments were determined using an equivalence of absorbance method with an anti-PnPs serotype 6B reference enzyme-linked immunosorbent assay (EIA). To assure accuracy, anti-PnPs EIA for serotype 14 antibodies, a previously assigned serotype, was performed concurrently. This method assures consistency of the new microgram-per-microliter assignments with previous antiserotype assignments to lot 89-S. The sum of the experimentally derived isotype assignments for anti-PnPs serotypes in lot 89-S agrees well with the separately determined total Ig assignment for each serotype. The lot 89-S assignments for serotypes 1, 5, 6B, 14, 18C, 19F, and 23F were used for pneumococcal conjugate vaccine clinical trial evaluation and to generate data in efficacy trials where serological correlates for protection have been proposed. The assignment of antibody concentrations to additional pneumococcal serotypes in this reference reagent facilitates the consistent and accurate comparison of serum antibody concentrations across clinical trials.

Antibodies, Bacterial↗
PubMed1998

Reference standards for vaccine-producing laboratories.

The inherent variability of the biological systems used for production of vaccines is much greater than that encountered in the production of pharmaceuticals. Therefore, producers of vaccines must take particular care to ensure that the different batches of a vaccine are of reasonable consistency and that the immunising activity of each batch is equivalent to that of the vaccine originally shown to be effective in the target species. This struggle for consistency has been the main motive for developing the range of reference standards which serve as fixed reference points during the production and quality control of a vaccine.

Animals↗
PubMed2005

Use of progressive glaucomatous optic disk change as the reference standard for evaluation of diagnostic tests in glaucoma.

PURPOSE: Progressive change in optic disk appearance has been suggested as the best available reference standard for glaucoma diagnosis. We evaluated the accuracy of scanning laser polarimetry (SLP) with variable corneal compensation to discriminate patients with documented progressive optic disk change from healthy subjects. DESIGN: Observational case-control study. METHODS: Glaucoma patients with documented evidence of progressive optic disk change as assessed by stereoscopic photographs were selected. Healthy control subjects had normal visual fields and normal clinical examination. All subjects underwent imaging with the GDx VCC scanning laser polarimeter. Receiver-operating characteristic (ROC) curves, sensitivities at fixed specificities, and likelihood ratios were calculated. RESULTS: Sixty-five eyes were healthy control patients. Seventy-one eyes had progressive optic disk change, of which 41 (58%) had abnormal visual field tests closest to the imaging date (perimetric glaucomatous optic neuropathy [GON]), and 30 (42%) eyes had normal visual fields (preperimetric GON). The GDx VCC parameter nerve fiber indicator performed best for discrimination between perimetric GON and normal eyes (AUC = 0.94; sensitivity = 93% for specificity > or =80%) as well as for the discrimination between preperimetric GON and normal eyes (AUC = 0.89; sensitivity = 83% for specificity > or =80%). CONCLUSION: SLP differentiated patients with documented progressive optic disk change from normal subjects and detected abnormalities in patients with confirmed diagnosis of preperimetric GON, suggesting that it may be useful for early glaucoma diagnosis. We suggest that progressive optic disk change should be used in the evaluation of diagnostic accuracy of imaging instruments for glaucoma.

Aged↗
PubMed1988

Spirometry and maximal expiratory flow-volume curve reference standards for Polynesian, European, and Chinese teenagers.

Lung function was compared and reference standards were determined in 1,007 Polynesian, European, and Chinese teenagers attending school in Tahiti (517 boys, 490 girls; mean age, 14.4 years). Spirometric study results and maximal expiratory flow-volume curves were measured using techniques recommended by the American Thoracic Society. Age, standing height, and weight were chosen as the independent variables for males, and age and standing height for females. Regression equations constructed with logarithmically transformed dependent variables provided accurate predictions. We observed significant racial differences: in the Europeans, forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were higher than the mean values predicted for the whole study population, while forced expiratory flow during the middle half of the FVC (FEF25-75%) and maximal expiratory flows after 25, 50, and 75 percent of FVC had been exhaled (V max 25, 50, and 75, respectively) were about equal to the mean values; in the Polynesians, volumes and flows were mostly lower than the mean; in the Chinese, FVC in boys and girls, and FEV1 in girls only, were lower, while the other flows were higher. The FEV1/FVC, FEF25-75%/FVC, Vmax25/FVC, Vmax50/FVC, and Vmax75/FVC were significantly higher than the mean in the Chinese boys and girls and often lower in the Europeans.

Adolescent↗
PubMed1982

Lung function in North American Indian children: reference standards for spirometry, maximal expiratory flow volume curves, and peak expiratory flow.

Reference standards of lung function was determined in 176 healthy North American Indian children (94 girls, 82 boys) 7 to 18 yr of age. Spirometry, maximal expiratory flow volume curves, and peak expiratory flow rate were measured using techniques and equipment recommended by the American Thoracic Society. Standing height was found to be an accurate predictor of lung function, and prediction equations for each lung function variable are presented using standing height as the independent variable. Lung volumes and expiratory flow rates in North American Indian children were similar to those previously reported for white and Mexican-American children but were greater than those in black children. In both boys and girls, lung function increased in a curvilinear fashion. Volume-adjusted maximal expiratory flow rates after expiring 50 or 75% of FVC tended to decrease in both sexes as age and height increased. Our maximal expiratory flow volume curve data suggest that as North American Indian children grow, lung volume increases at a slightly faster rate than airway size does.

Adolescent↗
PubMed1998

The normal adult human liver biopsy: a quantitative reference standard.

In assessing adult human liver histology, questions remain concerning the normal number of portal tracts and bile ducts in a liver biopsy. We therefore reviewed liver biopsies obtained with use of a percutaneous Menghini cutting needle (14G, internal diameter 1.6 mm), from 16 patients undergoing liver biopsy for screening procedures (age 49 +/- 14 years, +/-SD) and found to be normal by histological examination. The average aggregate length of the liver tissue was 1.8 +/- 0.8 cm (area of 16.4 +/- 10.7 mm2), representing 7 +/- 3 tissue fragments. Portal triads containing at least one profile each of a portal vein, hepatic artery, and interlobular bile duct numbered 11 +/- 6 per biopsy (range 3-23). Portal dyads, which did not contain one of these profiles, usually the portal vein, numbered 8 +/- 5 (range 1-18). On a per-specimen basis, 38% of portal tracts did not contain a portal vein, 7% did not contain a bile duct, and 9% did not contain a hepatic artery. Because of multiplicity of profiles within portal tracts, however, the average number of profiles per portal tract was 6 +/- 5 (range 2-35). Notably, on average there were 2.3 +/- 2.2 interlobular bile ducts per portal tract, compared to 2.6 +/- 2.3 hepatic arteries and 0.7 +/- 0.7 portal veins. The average minimum external diameter of interlobular bile ducts was 13 +/- 4 microm, of hepatic arteries 12 +/- 5 microm, and of portal veins 35 +/- 25 microm. Bile ducts greater than 30 microm in diameter were rare, only one each in two biopsies were observed. In contrast, probable canals of Hering were occasionally evident at the periphery of portal tracts (6 +/- 6 per biopsy) and within the lobular parenchyma as strings of cuboidal cells (5 +/- 5 per biopsy). We conclude that, although multiplicity of profiles is normal, portal dyads are almost as common as portal triads in normal peripheral liver tissue. On average, there are two interlobular bile ducts, two hepatic arteries, and one portal vein per portal tract, with 6 full portal triads per linear cm of tissue obtained by external Menghini biopsy technique with use of a 14G needle, equivalent to 0.8 +/- 0.5 portal triads per mm2. By serving as a reference standard for adult human liver histology, these findings may assist in the histopathological assessment of liver biopsies, particularly those performed for disease conditions featuring loss of intrahepatic bile ducts.

Adult↗
PubMed1981

Calibration of a strip test for urinary urobilinogen using a mercuric chloride assay with crystalline reference standards.

A strip test based on Ehrlich's reaction has improved specificity for urobilinogen in urine. Strip reactions are calibrated in mg/dl using a recently developed reference assay which is based on a mercuric chloride reaction and includes a crystalline reference standard. Strip reactions correlate well with the mercuric assay when the urine sample contains only urobilinogen. If a urine contains urobilin in addition to urobilinogen, the strip test gives slightly lower values than the reference assay. The strip test reacts only with urobilinogen but the reference assay measures urobilin as well as urobilinogen. Comparative data with both tests are included for normal and pathological urines. Reaction colors with the strip test have been characterized in L* a b* values, an international basis for color designation.

Calibration↗
PubMed1996

[The Human Menopausal Gonadotrophin Reference Standard (Control 961) of the National Institute of Health Sciences].

Raw human menopausal gonadotrophin (HMG) material was examined for preparation of the "Human Menopausal Gonadotrophin Reference Standard (Control 961)". The candidate material was assayed its follicle stimulating hormone (FSH) activity and luteinizing hormone (LH) activity against the 3rd International Standard for FSH and LH, urinary (71/264) by the augmented ovarian weight gain assay and the seminal vesicle weight gain test, respectively. The potency of the new standard was defined as 56 international units of FSH activity per mg and 61 international units of LH activity per mg as the result of 13 and 5 assays, respectively, in four collaborative laboratories.

Animals↗
PubMed2006

Synthetic musk fragrances in environmental Standard Reference Materials.

Synthetic musk fragrances have been measured in water, air, sediments, sewage sludge, and biota worldwide. As the study of the environmental fate and impacts of these compounds progresses, the need for Standard Reference Materials (SRMs) for these compounds to facilitate analytical method improvement and interlaboratory comparisons becomes increasingly important. The National Institute of Standards and Technology (NIST) issues environmental matrix SRMs with certified concentrations for a variety of persistent organic pollutants including polycyclic aromatic hydrocarbons (PAHs), chlorinated pesticides, and polychlorinated biphenyl congeners (PCBs). Until now synthetic musk fragrance concentrations have not been reported in NIST SRMs. The objective of this study was to provide reference values for several commonly detected synthetic musk fragrances in several NIST natural matrix SRMs. In this study five polycyclic musk fragrances [HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-gamma-2-benzopyran), AHTN (7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene), ADBI (4-acetyl-1,1-dimethyl-6-tert-butylindane), AHMI (6-acetyl-1,1,2,3,3,5-hexamethylindane), and ATII (5-acetyl-1,1,2,6-tetramethyl-3-isopropylindane] and two nitro musk fragrances [musk xylene (1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene) and musk ketone (4-tert-butyl-3,5-dinitro-2,6-dimethylacetophenone)] were measured in selected environmental SRMs. Gas chromatography-electron impact mass spectrometry (GC/EI-MS) was used for all analyses. HHCB was the most frequently detected synthetic musk fragrance and was detected in SRM 2585 Organic Contaminants in House Dust, SRM 2781 Domestic Sludge, SRM 1974b Organics in Mussel Tissue (Mytilus edulis), and SRM 1947 Lake Michigan Fish Tissue. It was not detected in SRM 1946 Lake Superior Fish Tissue or SRM 1945 Organics in Whale Blubber. Concentrations of HHCB in these SRMs ranged from 1.12 ng/g in SRM 1947 to 92,901 ng/g in SRM 2781. All of the polycyclic musk fragrances were detected in SRM 2781 and all of the target compounds were detected in SRM 2585.

Animals↗
PubMed1975

A study of the short-term retention and clearance of inhaled asbestos by rats, using U.I.C.C. standard reference samples.

Rats have been dosed over a 6-week period with U.I.C.C. standard reference samples of amosite, crocidolite and chrysotile A, each at three concentrations: 1,5 and 10 mg/m3. Mass concentrations in the exposure chambers were monitored daily. Because the M.R.E. gravimetric sampler was found to undersample some of these dusts at high concentrations, a sampler with a vertical elutriator was developed. Data on other physical parameters of the dust clouds were also obtained and it was found that the fibre number (greater than 5 micron in length) vs. mass correlation varied markedly between asbestos varieties. After dusting, the rats were sacrificed in five batches over a period of 4 months. The lungs of some animals were retained for pathological examination. This did not reveal any fibrosis although large numbers of fibres were visible, mostly within alveolar macrophages. The remaining lungs were analysed for their asbestos contents by a method based upon infrared spectrophotometry. The clearance data confirm earlier published reports that for rats dosed at similar mass concentrations of chrysotile and amphibole, those dosed with chrysotile retain considerably less dust in their lungs. The data also suggest that the retention and clearance of amphibole abestos may be dose related. Some mathematical treatment of the clearance data has been undertaken.

Animals↗
PubMed1982

Certification of lead concentration in standard reference materials by isotope dilution mass spectrometry.

In response to needs for analytical standards by researchers studying the exposure of humans to lead, a wide variety of environmental and "food" Standard Reference Materials have been prepared and certified for lead as well as for many other elements. Among the food types are SRM 1571, Orchard Leaves, 45 ppm; SRM 1575, Pine Needles, 10.8 ppm; SRM 1573, Tomato Leaves, 6.3 ppm; SRM 1566, Oyster Tissue, 0.48 ppm; SRM 1577, Bovine Liver, 0.34 ppm; SRM 1568, Rice Flour, 0.045 ppm; and SRM 1567, Wheat Flour, 0.020 ppm. These materials, intended for use in calibrating instruments and methods, have been certified by a definitive method, isotope dilution mass spectrometry. The advantages and disadvantages of this technique are discussed and some suggestions for the use of its isotopic selectivity in the study of lead in the human environment are presented.

Environmental Pollutants↗
PubMed2005

Determination of polybrominated diphenyl ethers in indoor dust standard reference materials.

Polybrominated diphenyl ethers (PBDEs) have been measured for the first time in three different indoor dust Standard Reference Materials (SRMs) prepared by the National Institute of Standards and Technology (NIST). Two of these, SRM 2583 (Trace Elements in Indoor Dust) and SRM 2584 (Trace Elements in Indoor Dust), have been certified previously for lead and other inorganic constituents. A third, SRM 2585 (Organics in Indoor Dust), is a new indoor dust reference material prepared by NIST which will be certified for various organic compounds (polycyclic aromatic hydrocarbons, pesticides and polychlorinated biphenyls) in 2005 including certified concentrations for 16 individual PBDE congeners and reference values for an additional three PBDE congeners. Dust SRMs were analyzed for 30 PBDE congeners using high-resolution gas chromatography combined with low-resolution mass spectrometry operated in both negative chemical ionization (GC/ECNI-MS) and electron impact ionization (GC/EI-MS) modes. Sensitivity was an order of magnitude higher using GC/ECNI-MS relative to GC/EI-MS. These SRMs have been characterized and compared to the three PBDE commercial products (pentaBDE, octaBDE and decaBDE). PentaBDE and DecaBDE were present in all three SRMs and were the dominant commercial products, making up approximately 33% and 58%, respectively. Recent studies suggest that house dust may be a leading source of human exposure to PBDEs. These SRMs are the first reference materials with certified concentrations for PBDEs, which will aid in validating future measurements of PBDEs in house dust and other similar matrices.

Chromatography, High Pressure Liquid↗
PubMed2005

Japanese standard reference material JDS Lot 2 for haemoglobin A1c. II: Present state of standardization of haemoglobin A1c in Japan using the new reference material in routine clinical assays.

BACKGROUND: In 2001, the Committee on Standardization of Laboratory Testing Related to Diabetes Mellitus of the Japan Diabetes Society (JDS) prepared and certified a new reference material for haemoglobin A1c (HbA1c), Lot 2. The standardization programme for HbA1c measurement in Japan is currently based on Lot 2, although some laboratories still use the previous material (Lot 1). The values assigned to Lot 2 were based on the consensus values for Lot 1 and should give the same results. Therefore, there should be no difference in the measured values no matter which calibrators are used. The Committee conducted a domestic survey in order to confirm this relationship. METHOD: In November 2002, four samples for HbA1c assay were sent to 795 laboratories as part of a national survey in Japan. Assays were performed using the laboratories' routine clinical methods. The coefficients of variation (CVs) of the reported values from all laboratories for the samples were calculated in order to determine the current level of standardization in Japan. RESULTS: The overall CVs in the measured values for the four samples ranged from 2.7% to 4.0%. Values from laboratories using calibrators based on Lots 1 and 2 were similar. CONCLUSION: The present state of standardization for the routine measurement of HbA1c in Japan, as indicated by the 2002 survey, is excellent. This should aid in the eventual conversion of Lot 2 to IFCC-based values from the results of the 2002 national HbA1c survey.

Blood Chemical Analysis↗
PubMed2007

The certification of a nominal 20 micromol/mol H2S/N2 standard reference material using two independent methods.

To support federal, state and local regulations on the amount of hydrogen sulfide (H(2)S) released into the atmosphere, the National Institute of Standards and Technology (NIST) has certified standard reference material (SRM) 2731 Hydrogen Sulfide in Nitrogen (nominal amount-of-substance fraction 20 micromol/mol H(2)S). Since it was first produced and certified in 1989, NIST has certified four separate lots of this SRM. In each case, the value assignment of the lot concentration was accomplished by comparison to a permeation tube-generated calibration curve. For the certification of the new lot, two independent methods were used to value-assign the concentration. In addition to the permeation tube method, a second method involving the dynamic dilution of a high-concentration gravimetrically prepared primary standard mixture containing H(2)S/N(2) was also used. Agreement between the two methods was 0.10% and the total uncertainty assigned to the lot concentration was 1.35% (relative).

Air↗
PubMed2004

Determination of caffeine, theobromine, and theophylline in standard reference material 2384, baking chocolate, using reversed-phase liquid chromatography.

A rapid and selective isocratic reversed-phase liquid chromatographic method has been developed at the National Institute of Standards and Technology to simultaneously measure caffeine, theobromine, and theophylline in a food-matrix standard reference material (SRM) 2384, Baking Chocolate. The method uses isocratic elution with a mobile phase composition (volume fractions) of 10% acetronitrile/90% water (pH adjusted to 2.5 using acetic acid) at a flow rate of 1.5 mL/min with ultraviolet absorbance detection (274 nm). Total elution time for these analytes is less than 15 min. Concentration levels of caffeine, theobromine, and theophylline were measured in single 1-g samples taken from each of eight bars of chocolate over an eight-day period. Samples were defatted with hexane, and beta-hydroxyethyltheophylline was added as the internal standard. The repeatability for the caffeine, theobromine, and theophylline measurements was 5.1, 2.3, and 1.9%, respectively. The limit of quantitation for all analytes was <100 ng/mL. The measurements from this method were used in the value-assignment of caffeine, theobromine, and theophylline in SRM 2384.

Cacao↗
PubMedDate not supplied

Instrumental neutron activation analysis of Standard Reference Material 1941, Organics in Marine Sediment. Element content and homogeneity.

The National Institute of Standards and Technology has developed a new Standard Reference Material 1941, "Organics in Marine Sediment." In addition to the organic constituents, over 30 elements have been determined by instrumental neutron activation analysis and prompt-gamma activation analysis. The homogeneity of the material was investigated and relative standard deviations of single-element concentrations in 250-mg samples were found to be 1% or less with regard to major inorganic constituents and rare earth elements. A slightly higher relative SD was found for elements that may stem from biological or anthropogenic input. The element concentrations determined in this work are discussed in comparison to concentrations in other similar reference materials. Concentrations for 31 elements will be included for information on the certificate.

Environmental Monitoring↗