Cytokeratin 19 fragments: a new marker for non-small-cell lung cancer.

We developed a new and automated assay for the detection of lung cancer associated cytokeratin 19 fragments in patients' sera/plasma. This new tumour marker assay CYFRA 21-1 was evaluated in technical and clinical studies using the multibatch analysers ES 300 and ES 600 from Boehringer Mannheim GmbH. The analytical performance was shown to be excellent. The clinical data from 2,037 patients demonstrate that for non-small-cell lung carcinoma CYFRA 21-1 has a higher diagnostic sensitivity compared to the established markers. Mainly for squamous cell carcinoma CYFRA 21-1 was superior (60%) to CEA (18%) or SCC (31%).

Immunoassay of CEA, CA 19-9, CA 125, and CA 15-3 on the automated systems ES 300 and ES 600: methodological evaluation from a multicentre collaborative study.

The analytical performance of the automated Enzymun Test System ES 300 and ES 600 (developed by Boehringer Mannheim) for the assay of the tumour markers CEA, CA 19-9, CA 125, and CA 15-3, was assessed from data collected in a multicentre collaborative study in which eleven laboratories were involved. Results of the 1990 cycle of the external quality assessment (EQA) scheme for tumour markers, supported by the Italian National Research Council (CNR), were also used in this evaluation. The within-assay and between-assay precision was found to be 2.0 and 4.3 CV% for CEA, 2.9 and 6.8 CV% for CA 19-9, 3.6 and 9.4 CV% for CA 125, 2.9 and 6.0 CV% for CA 15-3. The between-lab variability of the four tumour markers on ES 300 and ES 600 systems was 9.4, 10.6, 11.9, 9.2 CV% for CEA, CA 19-9, CA 125 and CA 15-3 respectively. These values were comparable to or better than those obtained with the most precise manual kits used by laboratories participating in the 1990 EQA cycle. The agreement between the results from the Enzymun Test and those obtained using other method/kits was evaluated by assaying control samples previously circulated either in the CNR EQA or in the German EQA. The regression analysis indicates that for CEA, CA 125 and CA 15-3 assays the results produced by ES 300 and ES 600 are in good agreement with the consensus means of the EQAs; CA 19-9 results exhibit a worse correlation and are generally lower than the consensus mean. The linearity of the assays for the four tumour markers was checked by dilution tests performed by participants in the collaborative study; in all cases the dilution of the sample did not affect the values obtained.

Evaluation of a new enzyme immunoassay system for free thyroxine (Enzymun-Test FT4).

Free thyroxine (FT4) represents the metabolically active fraction of the circulating thyroid hormone thyroxine (T4). In this paper the results of the evaluation of a newly developed FT4 assay are reported. This assay system is based on an enzyme-labelled one-step immunoassay. The within-run imprecision, checked using serum pools and several commercial reference materials, showed a coefficient of variation (CV) of between 0.8 and 9.8%, depending on the reference material used. The between-run imprecision showed a CV of between 1.0 and 13.2%. Accuracy experiments yielded values between 80 and 116%. When the new FT4 was compared with the calculation of an index for free thyroxine (FT4I; derived from either the ratio of T4/thyroxine binding coefficient of from T4/thyroxine binding globulin) in a number of samples in the hypo-, eu- and hyperthyroid range, a good correlation was obtained. The same was true when the new FT4 assay was compared with a widely used two-step radioimmunoassay (y = -0.146 + 0.943 x). In euthyroid subjects the measured FT4 concentration was 10.3-25.8 pmol/l. No effect was evident when the influence of EDTA and citrate was investigated, whereas addition of heparin led to an increase in FT4 concentration of about 12 to 15%. Investigation of the possible influence of a large number of drugs showed that probenezid, carbamazepine and furosemide led to an increase in the measured FT4 concentration. Dialysis increased the FT4 concentration, as measured in patients before and after haemodialysis. No effect of alteration in protein concentration and/or protein distribution of FT4 concentration could be detected. In pregnancy, FT4 values were within the normal range.(ABSTRACT TRUNCATED AT 250 WORDS)

Multicentre study of a new enzymatic method of cholesterol determination.

A new enzymatic method for the determination of cholesterol in serum and plasma was evaluated in 8 separate laboratories in comparison with routine and reference methods. Investigation of the analytical reliability in the 2-26 mmol/l measurement range showed the following results: At the set reading points (10 min at 25 degrees C and 5 min at 37 degrees C) the reaction shows complete substrate conversion. The colour complex is stable over a period of 60 min. The response to cholesterol is linear up to 26 mmol/l. Precision within the series was 0.6-2.8% in 20 determinations (coefficient of variation). Day to day precision was 0.5-3.3% in triple determinations of 10 days (coefficient of variation). Accuracy was studied with 2 samples (assigned value: 3.52 and 6.70 mmol/l respectively). In the case of sample 1 the mean for the 8 laboratories was 3.44, with a median of 3.44; for sample 2 the values were 6.68 and 6.72. The results demonstrate an excellent transferability. In comparison with other enzymatic procedures, the values found with the new test were 5-10% higher; these results agree at all concentration ranges with the reference methods of Abell & Kendall and with those from mass spectrometry.

Effect of ammonia on viability and blastogenesis of bovine lymphocytes.

The effect of addition of ammonia into the tissue culture on viability and functions of bovine lymphocytes was studied. The concentrations of ammonia in the tissue cultures represented toxic, subtoxic, and normal concentrations of ammonia in the bovine blood during clinical and subclinical urea toxicosis. Lymphocytes separated from peripheral bovine blood were incubated in control medium and test medium with various concentrations of ammonia and/or PHA or Con A. Viability of the lymphocytes was measured by trypan blue exclusion test and their mitogenic reactivity by incorporation of 3H thymidine into DNA of lymphocytes. Approximately 30% bovine lymphocytes were killed by ammonia in medium during 72 hours of incubation. Ammonia also affected the response of lymphocytes to stimulation with PHA or Con A as well as mixed lymphocyte culture reaction. The mitogenic response of lymphocytes was also reduced when lymphocytes were preincubated with ammonia for even 1 hour. The mitogenic response was not restored when the number of lymphocytes preincubated with ammonia was reconstituted to the initial concentration to compensate for the killed lymphocytes before stimulation with PHA. Therefore, addition of ammonia to the culture either killed lymphocytes or permanently impaired their functions.