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At least 19 recordsLinked to original sources
PubMed1979

[Characterization of an analytical method, comparison between two methods and electronic elaboration of data (author's transl)].

An experimental scheme for the evaluation of two parameters of validity of an analytical method, precision and accuracy, has been reported. Particular emphasis has been given to the problem of comparison between two methods. In the description a validity limit of the scheme has been given and certain critical points, commonly encountered in the measurement of the above mentioned parameters during the preparatory as well as the experimental phase, has been underlined. Further, with the help of tables and graphs, an example for electronic elaboration of the data obtained during the course of standardization of an automatic method for the determination of uric acid in serum according to the above scheme, has been given.

Autoanalysis↗
PubMed1975

[Determination of anti-cytomegalovirus antibodies by the immunoperoxidase method: comparison with the methods of complement fixation and immunofluorescence].

Indirect immunoperoxidase technique (IIP) has been employed for determination of IgG antibody titer to cytomegalovirus (CMV) in sera from 110 blood donors. Titers have been compared with complement fixation (CF) and indirect fluorescent antibody (IFA) technique titers, the latter being applied to determination of all specific antibody classes. Within variability range of the quality of reagents employed in different tests, it seems reasonable to conclude IIP technique is as sensitive as IFA and much more sensitive than CF test. Considering CF test is able to detect only IgG antibody, the advantage of using immunohistochemical techniques is obvious. Moreover IIP does not need fluorescence microscope and results reading is easier and can be delayed. Non-specific staining of Golgi area is shared by both techniques, but endpoint determination has to take into account only the nuclear virus-specific inclusion labelling.

Antibodies, Viral↗
PubMed1978

Comparison of product moment and rank correlation coefficients in the assessment of laboratory method-comparison data.

We have studied the effects of range and distribution of data on product moment and rank correlation coefficients when deviation from a linear relationship was due solely to experimentally produced random error. All correlation coefficients (Pearson r, Spearman rho, and Kendall tau) were markedly influenced by the range of the data, and, for the rank correlation coefficients, the effect of range varied for different data distributions. While correlation coefficients may be useful in assessing whether an association exists between two variables, they are not useful in assessing the degree of random error about the regression line when a strong linear association is presumed to exist between the two variables. Thus, neither product moment nor rank correlation coefficients are of value in analysis of laboraoty method-comparison data. The standard deviation of the residual error of regression should be calculated as a measure of the random error about the regression line.

Alkaline Phosphatase↗
PubMed1975

Background staining and sensitivity of the unlabelled antibody-enzyme (PAP) method. Comparison with the peroxidase labelled antibody sandwich method using formalin fixed paraffin embedded material.

The PAP procedure was compared with the peroxidase labelled antibody sandwich method and was found to be at least 20 times more sensitive. Background staining was reduced by the addition of normal swine serum to all the immune sera or by pretreating sections with it at the beginning of either method. The PAP procedure could be effectively reduced to a period of 1 hour or less.

3,3'-Diaminobenzidine↗
PubMed1979

Incorrect least-squares regression coefficients in method-comparison analysis.

The least-squares method is frequently used to calculate the slope and intercept of the best line through a set of data points. However, least-squares regression slopes and intercepts may be incorrect if the underlying assumptions of the least-squares model are not met. Two factors in particular that may result in incorrect least-squares regression coefficients are: (a) imprecision in the measurement of the independent (x-axis) variable and (b) inclusion of outliers in the data analysis. We compared the methods of Deming, Mandel, and Bartlett in estimating the known slope of a regression line when the independent variable is measured with imprecision, and found the method of Deming to be the most useful. Significant error in the least-squares slope estimation occurs when the ratio of the standard deviation of measurement of a single x value to the standard deviation of the x-data set exceeds 0.2. Errors in the least-squares coefficients attributable to outliers can be avoided by eliminating data points whose vertical distance from the regression line exceed four times the standard error the estimate.

Blood Chemical Analysis↗
PubMed1979

A methods comparison: clonazepam by gas chromatography-electron capture and gas chromatography-mass spectroscopy.

Clonazepam is an antiepileptic drug for which a number of analytical procedures have been presented, none of which have been subjected to comparison studies. We present two gas chromatographic (GC) methods involving distinct forms of detection for determining plasma or serum drug levels. Both methods involve simple extractions, common GC conditions, and routine data reduction. Both employ nitrazepam as an internal standard, require 1 ml of sample, and have a detection limit of 1 ng/ml. The two methods, GC-electron capture and GC-mass spectroscopy, are precise and accurate. Correlation of the two methods paired sample analysis gave a regression equation of y = 0.988x - 0.14 (n = 30, r = 0.971, p less than 0.001). We suggest that either method is a reasonable alternative for the clinical laboratory with the proper instrumentation.

Benzodiazepinones↗
PubMed1979

[A methodical comparison of respiration measurement in an incubation experiment (author's transl)].

For the determination of CO2-content from incubation experiments infrared-absorption, interferometer and titration methods were compared with regard of the reproduction of experimental results. The data obtained by titration were general higher. The middle coefficients of variation amounted for infrared-absorption 6.79%, interferometer 13.41% and titration 21.78%. The repititions, which are necessary for the statistical safety of the methods, are given. By the method of infrared-absorption the higher water-loss of the soil is reduced by water-saturation of the air in the incubation vessel.

Carbon Dioxide↗
PubMed1979

Statistical analysis of method comparison data. Testing normality.

A Lilliefors test of normality has been applied to data from precision and accuracy studies. Most data sets tested as non-normal. Simulation studies showed that the test is extremely sensitive to the rounded, narrowly distributed data that are typical of method performance studies in clinical chemistry. The Lilliefors test can be modified to be applicable to rounded data so that it gives fewer indications of non-normality. The authors conclude that the selection of a test of normality requires careful study of the properties of the test. Otherwise, the subsequent choice between parametric and nonparametric statistics may not be meaningful.

Chemistry, Clinical↗
PubMed1978

Demonstration of distinct allergens by means of immunological methods. Comparison of crossed radioimmunoelectrophoresis, radioallergosorbent test and in vivo passive transfer test.

An immunosorbent column was prepared containing a purified major allergen fraction from codfish (DS 22) covalently coupled to agarose. Sera from patients allergic to codfish were run through the column at pH 7.2. After extensive washing, the IgE retarded in the column was eluted with a buffer at pH2.5. The original sera and fractions from the chromatography experiments were examined by means of crossed immunoelectrophoresis (CIE), crossed radioimmunoelectrophoresis (CRIE), radioallergosorbent test (RAST) and in vivo passive transfer (PK) tests using the DS 22 from codfish and a crude codfish extract. The experiments demonstrated that the crude extract contained a minor codfish allergen (antigen-17-cod) which was distinct from DS 22. RAST was the most convenient technique for the identification of fractions containing allergenic activity. The PK tests served to prove the biological activity in vivo. CIE/CRIE were superior to RAST and PK tests regarding their ability to identify distinct allergens. Full agreement was found between results using different techniques including the immunosorbent experiments. Some of the radiostaining in CRIE, however, was misleading due to coprecipitation of DS 22 in several precipitates in the CIE preparations of the crude codfish extract.

Allergens↗
PubMed1979

Comparison of methods for immunocytochemical detection of rotavirus infections.

Rotavirus infections in intestinal tissues of animals or in tissue culture cells were detected by the immunocytochemical unlabeled soluble enzyme peroxidase antiperoxidase method. Comparison of the immunofluorescence and peroxidase antiperoxidase immunological staining techniques revealed that the two methods are equally sensitive for detection of rotavirus-infected cells. The peroxidase antiperoxidase technique offers the advantages of negligible nonspecific staining reactions, the use of a standard light microscope, the production of permanent slides, and the conservation of immunological reagents. The ability to detect antigens in paraffin-embedded tissues enhances the usefulness of the peroxidase antiperoxidase test for both prospective and retrospective studies.

Animals↗
PubMed1977

The estimation of fibrinogen levels in animal plasmas by a simple refractometric method. A comparison with a biuret method.

A comparison was made between a biuret (reference) method and a simple refractometric (test) method for measuring fibrinogen levels in 84 animal plasmas. Although the correlation between the two methods was high (4=0.90 P less than 0-001) there was considerable random variation in the refractometric results in relation to the biuret results. This was thought to be due in part to the fact that refractometric results could only be expressed in multiples of 2.4 g/litre. In spite of this limitation, the refractometric method, on the grounds of speen and simplicity, is considered to have worthwhile application for fibrinogen determinations in practice laboratory.

Animals↗