[Multisite validation of CDT measurement by the %CDT TIA and the Tina Quant %CDT kits]. / Validation multicentrique du dosage de la CDT par les méthodes %CDT TIA et Tina Quant %CDT.

The measurement of CDT (Carbohydrate Deficient Transferrin) is an essential biological tool in the diagnosis and follow-up of alcohol abuse. It is also employed as a marker of abstinence for the restitution of driving licences. However, the precision of measurement, and the between laboratory homogeneity of the results are still discussed. The ion exchange followed by immunodetermination of CDT is available in two products, the Tina Quant %CDT (Roche, Mannheim, Germany) and the %CDT TIA (Bio-Rad, Hercules, United States). This multicentre study was undertaken: 1) to evaluate the analytical characteristics of these kits and the homogeneity of the results from one laboratory to another, independently of the method used, 2) to validate the differences between the proposed normal values of both kits, 3) to study the possibility of using commercial control sera as external quality control. Four analytical systems were included in the study (Roche Modular/Hitachi 717, Beckman Coulter Immage and LX20, Dade Behring BNII). Determinations were carried out on pools of sera, commercial control sera, kit controls, and 30 serums of patients. These latter were also analyzed in capillary electrophoresis in order to establish correlations between the techniques. The calibrations were stable over one 2 weeks period. The repeatability of measurements spread out from 3,1% to 24,7%, for a mean value lower than 10%. The commercial control sera provided reliable results, with values adapted to a routine quality control use. The results of the Bio-Rad applications were lower by approximately 20% than those of the Roche application, which justifies the difference of the normal values (2,6% versus 3%), and an identical classification of the patients in at least 27 of the 30 samples. We conclude that the analytical quality of the compared techniques, even if it could be improved, is sufficient to guarantee a good reliability of the results. An external quality control could be proposed by using the control sera that we tested.

The influence of carbohydrate structures present in common allergen sources on specific IgE results.

BACKGROUND: Cross-reactive carbohydrate determinants (CCD) are well known interferants in specific IgE assays (sIgE). Glyco-epitopes are not restricted to CCD and extracts used to prepare in vitro tests contain many other glycoproteins able to bind glycan-specific IgE. The overall amounts of IgE-bindable glycan structures in allergen sources are unknown. OBJECTIVE: We aimed at quantifying the influence of N-glycan structures on IgE reactivity to commonly tested allergen sources. METHODS: IgE reactivity to 51 allergen extracts, one purified natural allergen and 10 recombinant allergens was measured on Phadia UniCAP system using 2 sera demonstrating significant levels of glycan-related IgE reactivity. Immobilized bromelain and horseradish peroxidase (HRP) were used to capture N-glycan-specific IgE from these sera. Residual IgE reactivity was measured for 42 allergen sources and 4 recombinant/purified allergens. RESULTS: An obviously excessive number of positive CAP-results were obtained with both sera, especially for plant-based allergen sources. Capture of glycan-specific IgE led to a decrease of serum IgE ractivity, variable among allergen sources and between sera. Among others, peanut results were proven largely interfered by the presence of glycan-specific IgE. Unexpectedly some allergen sources showed a slight influence of glycan-related reactivity, such as cockroach, mosquito, mussel, shrimp and domestic mites. CONCLUSION: In patients sensitized to pollens or to Hymenoptera venoms sIgE results should be interpreted with caution. One cannot substract the result of a glyco-reporter test (bromelain and/or HRP) in order to compute glycan-free slgE results for common allergen sources like peanuts. As long as the demonstration of a significant role for glycan structures in clinical allergic reactions is lacking, a simple pre-treatment able to discard glycan-specific IgE from serum would be useful to improve accuracy of in vitro diagnostic tests.

Interferences of glycerol, propylene glycol, and other diols in the enzymatic assay of ethylene glycol.

As an alternative to gas chromatography, the enzymatic UV assay of ethylene glycol is often used by emergency laboratories. Many variants of this technique have been published, all based on the reaction between NAD(+) and ethylene glycol in the presence of glycerol dehydrogenase (EC 1.1.1.6). We show that other alpha-diols interfere in this reaction. Some of them, like 2,3-butanediol, give false positive reactions; whereas other diols, e.g. glycerol and propylene glycol, interfere only when ethylene glycol is present in the sample and lower the ethylene glycol response; these interferents are of particular concern because some parenteral drugs used in emergency situations contain glycerol or propylene glycol in their vehicle. This drawback has hitherto been largely underestimated, and we think that ethylene glycol results obtained with these enzymatic techniques should be interpreted with caution, even if the sample is pre-treated with glycerokinase (EC 2.7.1.30); this pre-treatment effectively corrects the glycerol interference but not that of propylene glycol.

Results of the multicenter evaluation of a novel homogeneous immunoassay for digoxin based on the cloned enzyme donor immunoassay technology.

A new CEDIA assay for the measurement of digoxin in serum on random access analyzers was evaluated by twelve laboratories in Europe and the United States. Studies on the analytical range, reproducibility, calibration stability, recovery in controls, interlaboratory comparability, comparability with routine methods, and the effect of various interfering factors have been performed and the results are presented in this paper. The analytical performance was comparable to that of routine methods provided the manual pipetting step for pre-incubation was performed with accurate pipettes. A major advantage of the CEDIA Digoxin assay in terms of convenience is the simple two-point calibration procedure. Moreover, digoxin can be determined within 15 minutes after receiving the samples on random access analyzers like Boehringer Mannheim/Hitachi analysis systems. Thus, the CEDIA Digoxin assay represents an attractive alternative to the measurement of digoxin on dedicated immunochemical assay systems.

Results of the multicenter evaluation of a homogeneous immunoassay for digitoxin based on the cloned enzyme donor immunoassay technology.

We evaluated a CEDIA assay for the determination of digitoxin in serum on random access analyzers. The multicenter evaluation included studies on the analytical range, calibration stability and reproducibility of the new assay. Moreover, recovery in controls, transferability of results obtained in different laboratories, comparability with routine methods, and the effect of various interfering factors have been analyzed. Summarized the analytical performance was comparable to that of routine methods. The CEDIA Digitoxin assay represents an attractive alternative to established digitoxin immunoassays because it can be performed on random access analyzers, thus permitting the simultaneous determination of digitoxin and other serum analytes without sample splitting.

[Bibliography in clinical biochemistry: analysis of the literature beginning with a computerized data bank]. / Bibliographie en biochimie clinique: analyse de la littérature médicale à partir d'une banque de données informatisée.

In which fields of medicine, and in which journals does one publish the majority of articles which concern clinical biochemistry? We are trying to reply to this question by studying the basis of the biographical data developed in our laboratory, proceeding from the perusal of 290 journals and representing 16 802 articles stored from 1978 to 1983. Clinical Chemistry is the most important journal as far as number of articles is concerned, but less articles arises from journals of clinical biochemistry than from those of general medicine and internal medicine. The theme "lipoproteins and atherosclerosis" is the most prolific. It is studied in more detail. In a general way, a theme is rarely covered in a satisfactory manner with 5 journals or less. We think that, faced with the great dispersion of the same theme across the medical literature, our results will help the biologist to make a choice both from the point of view of contract and biographical research.

[Thermal degradation of tributyltin oxide and pulmonary toxicity of its combustion products in mice and guinea pigs]. / Dégradation thermique de l'oxyde de tributyletain (OTBE) et toxicité pulmonaire des produits de combustion chez la souris et le cobaye.

Relative to an industrial application, the authors relate results obtained from a peculiar study on the thermic degradation of bis (tri-n-butyltin) oxide (TBTO) at various temperatures and they account for the toxic effects observed after inhaling the combustion products in the mouse and guinea pig. Thermolysis of TBTO between 200 and 600 degrees C gives saturated hydrocarbon and olefin gas, a condensate of tetrabutyltin and dibutyltin oxide and a residue composed of stannous or stannic oxides according to the temperature. Pulmonary toxicity is very important at low temperatures but after heating, toxic effects decrease. The results are confirmed by localisation and histopathologic studies. At 600 degrees C no death appears but some behavioral troubles occur. It's possible that repeated exposures can induce delayed toxicity.

[Effects in the guinea pig of an aerosol with a tributylitin oxide base]. / Effets chez le cobaye, d'un aérosol à base d'oxyde de tributylétain (OTBE)

The authors report a toxicological study of bis (tributyltin oxide) (TBTO) given by inhalation (oily aerosol) to 105 Hartley albino guinea pigs. Doses vary from 1 mg to 0.1 mg of TBTO per liter of aerosol. Death occurs for doses of 0.2 mg per le more resistant than the male ones. The intoxication is marked by a period of ocular and nasal irritation followed by a short remission time, then death occurs after asphyxic convulsions. With doses less than 0.2 mg per liter of aerosol, we observe only an irritation without mortality after one hour intoxication. Seven days later the animals are alive. Because of its liposulibility, TBTO is present in the whole body, particularly in liver, kidney, lung, brain and heart. Histological study does not reveal any peculiar lesion of the examinated organs. Especially there is no specific alteration of the respiratory system. The merely observed trouble is a diffuse congestion.