[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.

Evaluation of minimal residual disease by interphase FISH in multiple myeloma: does complete remission exist?

As in other hematological malignancies, the achievement of a complete remission (CR) is important in multiple myeloma but is still based on common cytological and electrophoretic criteria. In this report, we studied 14 patients who achieved an apparent CR following high-dose therapy using fluorescence in situ hybridization (FISH) analysis. Although the results were difficult to interpret in two patients, 12 of 14 patients had unequivocal persistence of abnormal plasma cells in their bone marrow. Our results suggest that only a few patients, if any, are in true CR following one course of high-dose therapy and are in favor of post-transplantation treatments.

[HS CRP with Fumouze immunoturbidimetry and Dade Behring immunonephelemetry]. / Le dosage de la CRP ultrasensible par immunoturbidimétrie Fumouze et immunonéphélémétrie Dade Behring.

Increased concentrations of high sensitivity C-reactive protein are associated with increased risk for coronary heart disease. We report here a comparison of Fumouze hs-CRP turbidimetric method on Roche Diagnostics Hitachi 911 with Dade Behring BN II nephelemetric method. 134 samples were analysed. Within-run imprecision and between-run CV were good. Linearity was less satisfactory. Correlation study showed that without exceeding the maximum value of 6 mg/L, the hs-CRP method presented a good agreement with hs-CRP BN II method.

[Prescription, assay and interpretation of cardiac troponins tests: guidelines from SFBC-CNBC troponin working group]. / Recommandations sur la prescription, le dosage et l'interprétation des troponines cardiaques.

Troponin (I or T) has become the gold-standard marker in acute coronary syndromes during the last few years, as confirmed by a national survey realized within french clinical chemists, cardiologists and emergency practitioners. The importance of this marker and the heterogeneousness of circulating forms of troponin after myocardial necrosis fully justify international studies about standardization of this assay, which is a central bulk to reach a global market coherence. Checking analytical problems, although necessary, must be absolutely associated with an informed clinical interpretation. The knowledge of the crucial thresholds of each assay, the kinetic curves and the specificity limits of troponin assays allow the best use of their potential in diagnosis and prognosis together with an optimal patient care in very different clinical settings, in addition to others clinical and technical arguments. The quality improvement through successive generations of assay kits must nowadays persuade the physicians never to ignore a significant and valid troponin increase, which mainly reveals a cardiac injury, whatever its origin.

[Difficulties with immunofixation interpretation]. / Difficultés d'interprétation de l'immunofixation.

Immunofixation is widely used for monoclonal gammapathies identification and Bence Jones proteinuria research. In more of cases, interpretation is easy, but some difficulties persist. Five examples are presented and their causes are analysed; in our first case, seric immunofixation shows the problem generated by additives. These components are added to optimize antigen- antibody reaction but they can induce interferences; three cases of urinary immunofixation showing Bence Jones proteinuria with/or without complete monoclonal immunoglobulin are presented. The variability of immunsera avidity is sometimes a problem; a case of light chain disease associated with monoclonal IgA illustrate difficulties of interpretation when precipitin bands have nearly the same migration. These examples underline the great importance of regular controls of immunologic reagents. The use of two antisera with the same specificity but different origin is recommended in order to resolve difficulties with interpretation of immunofixation.

[Pericardial C-reactive protein. A marker of agonal cardiac disease ?]. / La protéine C-réactive péricardique. Un marqueur de la souffrance cardiaque agonique?

We studied the influence of the agonal period on the concentrations of acute phase proteins in biological fluids obtained from 26 autopsy cases. We found significant differences for C-reactive protein concentrations in serum and in pericardial fluid, between short and long agonies. The other acute phase proteins studied (alpha-1 antitrypsin, alpha-2 macroglobulin, haptoglobin) failed to show any significant difference in serum and pericardial fluid levels between the two types of agony. The increase in C-reactive protein level in the pericardial fluid is attributed to an "agonal pericarditis" which may result from an agonal myocardial necrosis. Our results could be of interest in forensic medicine.

Biochemical study of KB-cell receptor for adenovirus.

Three different approaches were used in an attempt to characterize the KB-cell receptor for adenovirus: affinity chromatography, immunoadsorption and cross-linking with a cleavable bifunctional reagent. The first system used an affinity gel consisting of adenovirus-fibre projection linked to Sepharose matrix by an intermediate bis(aminopropyl)amine arm, the amino groups of the fibre ligand being preserved by prior citraconylation. The second system consisted of adenovirus complete penton capsomere attached to anti-(penton base) antibody and cross-linked to polyacrylamide particles with glutaraldehyde. In this latter affinity model, the penton-fibre projection was appropriately oriented outwards, as in the virus particle. Both affinity systems permitted isolation from a KB-cell plasma-membrane extract of fibre-binding and penton-fibre-binding protein material, which inhibited adenovirus attachment. The penton-immunoadsorbent appeared more efficient and more specific than the affinity column of fibre-bis(aminopropyl)amino-Sepharose gel in specific activity of inhibition of adenovirus attachment. The third method consisted of reversibly cross-linking KB-cell receptor proteins with adenovirus particles by means of a cleavable di-imidoester and isolation of the complexes by sucrose-density-gradient centrifugation. Polypeptide analysis on sodium dodecyl sulphate/polyacrylamide gel of labelled KB-cell surface proteins, selected by the different procedures, showed that three major protein subunits of 78000, 42000 and 34000mol.wt. were common to the three selection systems. A possible model for the structure and function of the KB-cell receptor for adenovirus is discussed.

CSF isoelectrofocusing in a large cohort of MS and other neurological diseases.

The present study was performed in order to confirm the diagnostic value of isoelectrofocusing (IEF) in a large multiple sclerosis (MS) cohort and to evaluate the various neurological diseases probably to present a similar IEF profile. The cerebrospinal fluid (CSF) of 1292 patients with neurological diseases was studied by IEF. After a follow-up of 2-36 months, we only included patients with a definite MS or confirmed diagnosis of other neurological diseases (OND). MS was diagnosed in 407 patients and OND in 593 patients. For patients in whom three or more oligoclonal bands (OCB) were detected, IEF results showed a sensitivity of 85% and a specificity of 92% for the diagnosis of MS. The positive and negative predictive values were 86.5 and 90%, respectively. Inflammatory and infectious disorders of the central nervous system represented the main affections associated with OCB, including human immunodeficiency virus encephalitis, Lyme disease and less frequently Sjogren syndrome. Furthermore, when OCB were observed, 10 or more bands were more frequently found in MS than in OND (P < 0.0001). IEF of the CSF is a reliable method for the diagnosis of MS. The absolute number of bands may help to discriminate between MS and OND.

Identification of IgG-specific oligoclonal banding in serum and cerebrospinal fluid by isoelectric focusing: description of a simplified method for the diagnosis of neurological disorders.

Clinical laboratory procedures using cerebrospinal fluid (CSF) to assist in the diagnosis of multiple sclerosis (MS) are based essentially on the determination of oligoclonal bands (OB) in CSF and not in serum. To date, the techniques using isoelectric focusing (IEF) have represented one of the most efficient methods for detecting supernumerary bands in CSF but unfortunately were not always compatible with a routine use. Here, we describe a revised method of IEF suitable for the diagnosis of neurological disorders. The kit-based technique was simplified and the present procedure allowed an easier execution, reduced the overall analysis time and permitted an uncomplicated intepretation of oligoclonal profiles. Moreover, the technique developed was very sensitive and specific for the diagnosis of MS diagnosis. In conclusion, the IEF protocol described in this report is suitable for OB detection in any laboratory.