[Evaluating an internal quality control procedure: application to multidimensional control].

Internal quality control keeps in constant evolution in the industrial world. Introducing in clinical chemistry new QC methods derived from the industrial practice raises the point of the means for their evaluation. The main evaluation criteria are discussed in this paper.

The impact of clinical biochemistry on university education in France.

In France, clinical biochemistry, similar to other disciplines of laboratory medicine, is taught in both the regular medical and pharmacy curricula, but medical teaching is oriented more towards the interpretation of laboratory findings than test performance. At present, there is no compulsory program of lifelong continuing education, but it is planned to introduce such an obligation in the near future. The practice of laboratory medicine is regulated strictly by the national Health Administration.

Antibody quantitation in human and veterinary medicine.

The determination of antibodies is a matter of clinical importance since it may prove or disprove the existence of an immune reaction against a specific foreign or autologous antigen. It is useful to monitor the immune response against a vaccine or the disappearance of injected therapeutic antibodies and in fundamental immunological research or in industrial R & D. However, this determination of this particular analyte cannot end up with a significant mass measurement, as a result of the heterogeneity of the antibodies present in most samples (with the exception of monoclonal antibody research).

Standardization of immunoassays.

The aim of standardization is to ensure that assays of the same analyte in the same samples, done at different places or at different times or both, can be readily compared. Standardization is especially desirable for immunoassays because all external quality assessment surveys have shown that this type of method involves a much greater variability than traditional assays. A major problem in immunoassays is that the recognition of the analyte is determined by the reagent (i.

Criteria for the selection of a solid phase to be used in immunoassays.

Heterogeneous immunoassays are very sensitive and only limited in terms of performance by non specific binding. They require separation of free from bound fractions and concomitant use of a solid phase coated with an immunoreactive component (i.e.

[Principles and methods of immunological diagnosis in infectious and parasitic pathology].

Immunological methods have always represented a major contribution to the diagnosis of infectious diseases. Recent technical advances in immunochemistry make this contribution even more essential than in the past. The author reviews the classic principles of immunological diagnosis in infectious pathology.

Distribution of Trop 3 and 4 antigens as defined by monoclonal antibodies raised against a human choriocarcinoma cell line.

The reactivities of Trop 3 and 4 monoclonal antibodies (MAbs) were studied on human term and 7-week extraembryonic membranes, adult tissues, and cell lines. Trop 3 MAb reacted with cells of chorionic villi, decidua, amniotic epithelium, and basal plate trophoblast. Trop 4 MAb reacted only with syncytiotrophoblast.

A novel enzyme immunoassay for total thyroxine using immobilized antibodies and hydrophobic chromatography purified thyroxine-peroxidase conjugate.

A new and simple competitive enzyme immunoassay method for the measurement of total thyroxine in serum is described. Anti-thyroxine antibodies, raised in sheep with a bovine serum albumin-thyroxine conjugate prepared with carbodiimide as coupling initiator, were physically adsorbed onto a large surface area polypropylene support. Competition occurred between thyroxine in the sample and a thyroxine-peroxidase conjugate prepared with a glutaraldehyde spacer and further purified by octyl Sepharose hydrophobic chromatography.

Affinity chromatography of rat alpha-fetoprotein on estradiol-agarose columns.

The use of 17 beta-estradiol-17-hemisuccinate coupled to agarose beads is shown to be a rapid and simple procedure for the isolation of alpha-fetoprotein (AFP) from amniotic fluid. The elution profile of the affinity column shows that AFP is sufficiently retarded by the gel to perform the purification of the protein without specific elution with high-affinity AFP ligands. Rat AFP appeared as a single symmetric peak, a profile that is in good agreement with the existence of a single population of AFP molecules having estrogen-binding properties.

Effect of pH on the recovery of human alpha-fetoprotein from immunosorbent columns. An improved elution procedure.

A slow decrease in pH was shown to be more efficient in eluting human alpha-fetoprotein bound to Sepharose-immobilized antibodies than a pH shock. With this method, nearly 50% of the antigen absorbed onto the column was recovered in a single peak whereas the yield was 3 times lower in the case of a single elution at pH 2.6.

Alpha-fetoprotein favours accumulation of estrone but not arachidonic acid into the fetal and new-born rat brain.

Tritriated estrone or arachidonic acid, two high affinity ligands for rat alpha-fetoprotein (AFP), were injected into adult, pregnant or newborn Sprague Dawley rats in order to evaluate their possible transfer into the brain. This study shows that the developing brain accumulates the estrogen but not the fatty acid, suggesting that the uptake of AFP by the developing brain is a mechanism for transporting estrogens, but not fatty acids.

Immunoassay of melatonin with enzyme-labeled antibodies.

This paper reports a non equilibrium competitive enzyme immunoassay method using enzyme-labeled antibodies, for the quantitation of melatonin in chloroform-extracted samples. Its principle is as follows: methoxytryptamine hemisuccinate-human serum albumin conjugate physically absorbed onto a polystyrene sphere and melatonin to be measured, compete for a limited and fixed amount of peroxidase-labeled anti melatonin IgG. After incubation and washings the enzymatic activity bound to the sphere was measured with a chromogenic substrate.

Interaction of retinoids and bilirubin with the binding of arachidonic acid to human alpha-fetoprotein.

Human alpha-fetoprotein (HAFP) has three binding sites for polyunsaturated fatty acids with association constant Ka = 1.8 X 10(7) M-1. One of these binding sites overlaps with a retinoid binding site with Ka = 2.

Comparative binding properties of rat and human alpha-fetoproteins for arachidonic acid and estradiol.

Rat and human alpha-fetoproteins, (AFP) were able to bind arachidonic acid with high affinity (Ka = 10(7) to 10(8) M-1). Nevertheless, a great difference was found in the binding capacity of these two proteins. Rat AFP was shown to possess one high affinity binding site and several (12-13) low affinity sites while human AFP presented three equivalent binding sites for polyunsaturated fatty acids.

Human alpha-fetoprotein-fatty acid interaction.

Human alpha-fetoprotein (AFP) is able to bind arachidonic acid with high affinity Ka = 10(7)M-1 and a limited number of binding sites NS = 3. Thirty different fatty acids were tested by competition using labelled arachidonic acid as tracer. This experiment demonstrated a great specificity for the fatty acid-AFP interaction.

Inhibition of rat alpha-fetoprotein-estrogen interaction by adult rat ovarian extracts--role of unsaturated fatty acids.

Thin layer chromatography with four different solvent systems enabled us to show that ovarian extracts contained nonesterified unsaturated fatty acids able to compete with estradiol on the alpha-fetoprotein binding site. Gas chromatography demonstrated a high level of oleic and linoleic acids and the presence of arachidonic acid, a strong competitor of the rat alpha-fetoprotein-estrogen interaction. Arachidonic acid is a precursor of prostaglandins thus we suggest that its binding to AFP might play a role in the AFP-mediated ovarian regulation previously demonstrated.

On rat alpha-fetoprotein as a fatty acid carrier. Influence of the structure of fatty acids.

Fatty acids interfere with rat alpha-fetoprotein-estrogen interaction. We present here a quantitative study of the association constants for the binding to alpha-fetoprotein of different fatty acids. It can be concluded that fatty acids bind more strongly if the number of carbon atoms increases with the number of double bonds.

An enzyme immunoassay design using labelled antibodies for the determination of haptens. Application to methotrexate assay.

A competitive enzyme immunoassay with labelled antibodies has been developed for methotrexate (MTX). Methotrexate in the sample and a constant quantity of this hapten physically absorbed to polystyrene spheres through a methylated bovine albumin carrier were allowed to compete for a limiting amount of peroxidase labelled antibody. After washing, the residual enzyme activity bound to the solid phase was measured.

Improvement of the demonstration of A, B, H surface antigens in bladder tumors by a simple immunofluorescence technique.

The presence of A, B and H blood group antigens in paraffin-embedded tissue sections was demonstrated with a routine direct and indirect immunofluorescence technique. Natural and human antisera were used for 102 biopsy specimens of the various blood groups, including normal mucosa and vesical tumors. This technique allows a more precise description than the specific red cell adherence reaction of the differentiation pattern of the tumor itself and of the surrounding and distant mucosa.

[Blood group ABO (H) cell surface antigens in bladder tumours invading the chorion. Prognostic value of their determination by immunofluorescence. Retrospective study of one hundred and twenty-five cases].

The authors have studied 125 stage A bladder tumours with a follow-up period of at least 5 years. The ABH cell surface antigens were collected by a double-layer immunofluorescence technique which has already been described. All the cross sections were read by the same pathologist who knew nothing about the clinical developments.

Transfer, tissue localization and proliferation of fetal cells in pregnant mice.

Matings between Rb7-Rb7 male mice, possessing the Rb7 chromosomal marker, with CBA, C57/B1, Swiss or F1 BALB/SJL females were carried out to determine whether fetal cells transferred into maternal tissues. Rb7 cells undergoing spontaneous mitosis were sought in maternal blood, bone marrow, thymus, para-aortic lymph nodes, Peyer's patches and liver. Proliferation fetal cells were unequivocally demonstrated in maternal spleen and bone marrow, 12-21 days after mating.

Role of alpha-fetoprotein (AFP) in the regulation of ovarian activity during hepatocarcinogenesis and post-natal development.

N-fluorenylacetamide produces an augmentation of serum AFP which is accompanied by a drastic decrease of ovarian activity. A passive augmentation of the AFP level of adult rats, produced by injection of this protein provokes the same phenomenon: i.e.