Biomedical subjects

B Leerkes

Publications and source records attributed to B Leerkes.

4 recordsLinked to original sources

PubMed1995

Evaluation of performance characteristics of automated measurement systems for allergy testing.

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 when 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. The combination of the two DPC systems did not offer any advantages over Pharmacia CAP System from the handling or work flow point of view.

Adolescent↗

PubMed1995

Evaluation of the DPC IMMULITE random access immunoassay analyser.

The automated immunoassay analyser, IMMULITE, developed by DPC, was evaluated. IMMULITE is an automated system that allows random access in combination with immediate and continuous access. In this study we evaluated the IMMULITE on four panels of analytes: thyroid, fertility, tumour and "non-routine" markers. We observed good within-rum reproducibility (ranging from 2.3-15.9% CV, for low controls, to 2.7-8.7% CV for high controls) as well as between-day imprecision (ranging from 3.7-24.6% CV for low controls, to 2.5-11.8% cv for high controls). The analytical sensitivity of the assays ranged generally from very sensitive to acceptable. The dilution curves for all assays were nearly linear i.e. the maximum deviation of the observed from the expected recovery was 8%. Correlation between IMMULITE and other assays (AxSYM, IMx, TDx, AIA-1200, DPC-c. a. c., Medgenix) varied from r = 0.931 to r = 0.994, except for lutropin and parathyrin with coefficients of correlation of r = 0.594 and r = 0.591. The slopes of the regression lines ranged from 0.745 to 1.327, except for parathyrin where a slope of 2.389 was found. Inter-laboratory correlation was very good between the two locations (Sittard and Apeldoorn) and varied from r = 0.984 to r = 0.999; slopes of the regression lines varied from 0.924 to 1.086. We conclude that the DPC-IMMULITE system is suitable for testing routine analytes in random access mode as well as for testing "non-routine" analytes on an automated immunoassay analyser.

Antigens, Neoplasm↗

PubMed1990

Quantitation of human chorionic gonadotropin with the Abbott IMx immunochemistry analyzer.

The analytical performance of the Abbott IMx automated system was studied and initial results from the human chorionic gonadotropin assay are presented: Within run and between day precision was good, the majority of all CVs lying between 3 and 5%; Patient results showed excellent comparability with our routine method; No significant specimen-related carry-over was detected; The automated IMx dilution protocol was found to be superior to the manual procedure; The usefulness of the instrument in routine use and as a "Stat" analyzer was very good.

Autoanalysis↗

PubMed1988

Nine rheumatoid factor assays compared.

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.

Agglutination Tests↗