Summary:In this study we have investigated five quantitative and three semi-quantitative rheumatoid factor assays and the Rose-Waaler assay in 120 patients suffering from rheumatoid arthritis and in 76 with other systemic diseases. All tests measure the IgM anti-IgG antibodies.The correlations between the quantitative tests were all higher than 0.86 and much better than between the quantitative and semi-quantitative tests and the semi-quantitative tests themselves (r between 0.22 and 0.85). The within run and between run precision studies for the quantitative tests showed CV values lower than 16%.In spite of the standardisation on the WHO and the Center of Disease Control Reference Preparation we found important differences in patient results.From an analytical point of view, the quantitative assays for rheumatoid factors show certain advantages over the traditional haemagglutination tests.
j Summary: Reliability of test results, convenient handling and flexibility are major requirements on automated ! immunoassays systems. To investigate to what extent these requirements were met by the Pharmacia CAP and DPC IMMULITE and DPC Microplate Systems, we evaluated several performance characteristics of assays of specific IgE against some common inhalant allergens as well as the atopy tests Phadiatop (Pharmacia CAP System) and AlaTOP (DPC IMMULITE and Microplate System).Comparing Phadiatop and AlaTOP results (n = 95) to clinical data, the sensitivity was found to be 97% in the Pharmacia CAP System and 82% in the AlaTOP-DPC Microplate System and 88% with AlaTOP-IMMULITE. Specificity was in all cases higher than 90%.The pooled total variation was more than twice as high with the DPC Microplate System as compared to the Pharmacia CAP System in our first investigation. A second investigation showed similar values.The investigation of systematic differences showed that the error contribution of sample related differences between the systems was even larger and far exceeded the analytical variation. Thus the two methods do not seem to be measuring the same specific IgE antibodies. In 8 out of 8 cases with the Pharmacia CAP System positive and DPC negative results and in 2 out of 2 cases with DPC positive and Pharmacia CAP System negative results, the presence of IgE antibodies could be confirmed by IgE immunoblotting. Serum dilutions showed very irregular O/E patterns for the DPC Microplate System.There was no effect wheri adding non-specific IgE to serum samples. Addition of competing IgG antibodies showed a moderate decrease in binding of specific IgE in the Pharmacia CAP System when increasing amounts of IgG were added. The effect in the DPC Microplate System was more pronounced with large decreases, or increases of measured values even at lower concentration of the competing antibody. The results may indicate insufficient allergen concentration in the DPC assay and draw attention to the risk for undesirable complex formation between allergen and antibody in solution.
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EGGSTEIN'S method for the enzymatic assay of triglycerides was adapted to the Perkin Elmer C-4 Automatic Analyzer and the repeatability, recovery, linearity and drift within a series were checked. The assay of triglycerides with the Perkin Elmer C-4 Automatic Analyzer was found to be highly reliable and rapid. With a few exceptions, it was found to be not necessary to estimate the free glycerol in addition to the total glycerol, which considerably reduces the length of this procedure.Die Methode von EGGSTEIN zur enzymatischen Bestimmung von Triglyceriden wurde an den automatischen Analysator Perkin Elmer C-4 angepaßt. Wiederholbarkeit, Wiederfindung, Linearität und Drift innerhalb der Serie wurden untersucht. Die Bestimmung der Triglyceride mit diesem Gerät ist sehr zuverlässig und schnell. Abgesehen von einigen Ausnahmen ist die Bestimmung des freien Glycerins neben dem Gesamtglycerin nicht erforderlich, wodurch der Zeitaufwand wesentlich verringert wird.
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