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Biomedical subjects

M E Toubert

Publications and source records attributed to M E Toubert.

40 records · Page 3Linked to original sources
PubMed1990

Radioimmunoassay of immunoreactive erythropoietin as a clinical tool for the classification of polycythaemias.

Radioimmunoassay of erythropoietin (EPO) has been used for evaluating its clinical usefulness in distinguishing polycythaemia vera (PV) from pure erythrocytosis (PE). A normal log distribution (13.40 mU/ml +/- 2.45) was observed in the 66 reference samples. Similar results were observed in 29 pure thrombocytaemias (13.23 +/- 5.19). In PV patients, whether in clinical remission or in active phase, the EPO titer was lower than normal values (respectively 7.32 +/- 3.63 and 6.59 +/- 2.75), without any correlation with the haematocrit (44 to 51% and 52 to 71%). In the anaemic cases (excessive therapy, spent phase, myelofibrosis), a slight excess of EPO titer was observed, but less than expected when taking the hematocrit into account. In contrast, pure erythrocytosis is a very heterogeneous group, with the highest EPO values in the well-defined secondary cases, and normal or slightly excessive values in most of the cases, but with some low values similar to those observed in PV cases. In term of PV diagnosis, a 90% predictive value is observed when a "cut-off" value of 11 mU/ml is chosen. When the "cut-off" is 16 mU/ml, no PV case was observed beyond this value. We conclude that EPO assay is useful in myeloproliferative diseases from a practical point of view.

Diagnosis, Differential↗
PubMed1989

Relationship between immunological structure and biochemical properties of human thyroid peroxidase.

Although the primary structure of human thyroid peroxidase (hTPO) has been recently deciphered, little is known about its spatial conformation. Such information is of crucial importance in any attempt to relate the structure with the function of hTPO. To probe the antigenic surface of hTPO and to correlate its immunological structure to its biochemical properties, we used 13 monoclonal antibodies (mAb) displaying various affinity for hTPO. Criss-cross experiments showed 7 clusters of reactivity which were interpreted as reflecting 7 epitopes on the surface of the hTPO molecule. Extending our analysis to partial and nonsymmetrical cross-reactivities, these epitopes were shown to be localized in 4 antigenic domains of the hTPO. We further investigated the nature of these 7 hTPO epitopes by testing mAb binding to peroxidases from various origins and chemically modified hTPO; 3 epitopes were shown to be evolutionary conserved, and 5 resistant to reduction and denaturation. We also analyzed the role of the hTPO epitopes in the enzymatic activity and autoimmune targeting of the molecule. Nine epitopes were shown to be localized at the vicinity of both catalytic sites as the binding of their respective mAb modulated the enzyme activity. Autoantibodies from patients presenting with autoimmune thyroid disorders were essentially directed to epitopes similar or adjacent to those recognized by 8 of the 13 mAb and present on only 2 antigenic domains of hTPO. Taken together these data allowed us to propose a tentative map of the surface of the hTPO molecule which associates its epitopic structure with its biochemical functions.

Antibodies, Monoclonal↗
PubMedDate not supplied

Evaluation of total PSA assay on vitros ECi and correlation with Kryptor-PSA assay.

BACKGROUND: An increasing number of multiparametric immuno-analysers for PSA assays are available. As different immuno-assays may vary in their analytical quality and their accuracy for the follow-up of patients, expertise is necessary for each new assay. METHODS: The PSA assay on the Vitros-ECi analyser has been evaluated and compared with the PSA assay from the Kryptor analyser. RESULTS: Variation coefficients were 0.91 to 1.98% for within-run assays, and 4.2% to 5.4% for interassay (PSA levels = 0.8 microgram/L to 33.6 micrograms/L). Dilution tests showed 93 to 136% recovery until 70 micrograms/L PSA. Functional sensitivity was estimated at 0.03 microgram/L. Equimolarity of the test was confirmed. Correlation of PSA levels measured with Vitros-ECi and Kryptor analysers displayed a correlation coefficient r2 of 0.9716. The half-lives and doubling times of PSA were similar using both methods. CONCLUSION: Vitros-ECi PSA assay meets the major criteria for the management of prostate cancer patients.

Adenocarcinoma↗