[Nephelometry or turbidimetry for the determination of albumin, ApoA, CRP, haptoglobin, IgM and transthyretin: which choice?]. / Turbidimétrie ou néphélémétrie: quel choix pour les dosages de l'albumine, l'ApoA, la CRP, l'haptoglobine, l'IgM et la transthyrétine?

Nephelometry, which is considered as the reference method for serum proteins determination requires a specific equipment. The majority of protein determinations are therefore carried out on biochemistry automats using turbidimetry. The objective of a CNBH group (Collège national de biochimie des hôpitaux) was to compare nephelometry and turbidimetry for 7 automats: 2 nephelometers, the BN Prospec (Dade-Behring) and Immage (Beckman-Coulter) and 5 biochemistry systems using turbidimetry, the Integra and Modular (Roche Diagnostics), the LX20 (Beckman-Coulter), RXL (Dade-Behring) and AU (Olympus). The study was based on the determination of sera collections (albumin, ApoA, CRP, haptoglobin, IgM, transthyretin) of 140 samples each: 110 limpid samples and 30 samples called HLI (hemolytic, lipemic or icteric). Fifteen hospitals took part to this work. An ANOVA analysis on limpid samples and quality control sera concluded to an "automat" effect for the 6 tested proteins but did not show a "method" effect, (i.e. nephelometry versus turbidimetry). On the other hand, the transferability of the results was expected to be better and an effort on the choice of the antibodies and the standardization procedures should be made.

Assessment of a new immunoassay for serological confirmation and discrimination of human T-cell lymphotropic virus infections.

The present study evaluated a new confirmatory assay for antibodies to human T-cell lymphotropic virus type 1 and 2 (HTLV-1 and HTLV-2) proteins performed with serum samples from various commercial sources. The new test is a line immunoassay (LIA) with a nylon membrane sensitized with the most relevant antigens of HTLVs: the envelope gp46 and gp21 as well as the gag p24 and p19 antigens, represented by either recombinant proteins or synthetic peptides. A total of 176 serum or plasma samples were tested, of which 66 were HTLV-1 positive, 72 were HTLV-2 positive, and 38 were HTLV negative; of the 38 HTLV-negative samples 23 were indeterminate by Western blotting (WB). Serially diluted samples (n = 33) from HTLV-1- and HTLV-2-infected patients were also analyzed to determine the sensitivity of the new assay. The new confirmatory assay (INNO-LIA HTLV) performed markedly better than WB assays for those samples reactive by screening. Accurate confirmation of the presence of HTLV-1 and HTLV-2 antibodies and accurate discrimination of HTLV-1 and HTLV-2 antibodies were obtained for all the HTLV-seropositive samples. Due to its enhanced specificity and sensitivity, the new assay not only improves the ability to confirm and discriminate HTLV infections but also eliminates the vast majority of WB-indeterminate and false-positive specimens.

Influence of the degree of exposure to lead on relations between alcohol consumption and the biological indices of lead exposure: epidemiological study in a lead acid battery factory.

Alcohol has been shown to interact with lead to influence haem biosynthesis. The aim of this study was to define the dependence of this interaction on the degree of exposure to lead. Exposure to alcohol was estimated by measurement of alcohol concentrations in a sample of urine collected during the morning (AlcUM) (0.82 (SD 4.36) mmol/l) and in a sample collected during the afternoon (AlcUA) (1.15 (SD 3.49) mmol/l). The biological monitoring of exposure to lead included measurements of blood lead (Pb-B) (1.82 (SD 0.72) mumol/l), urinary delta-aminolaevulinic acid (ALAU) (35.33 (SD 28.00) mumol/l; d = 1.015), and erythrocyte zinc-protoporphyrin (ZPP) (112.90 (SD 83.71) nmol/mmol Hb) concentrations. The study of the influence of the degree of occupational exposure to lead on relations between alcohol consumption and effects of the exposure to lead led to the consideration of two different groups--namely, mildly and strongly exposed subjects. In the first group, individual biological susceptibility seemed to play a preponderant part. In the second, the pool of lead present in the body seemed to be sufficiently important to mask the effects of individual susceptibility.

Effect of alcohol intake on human apolipoprotein A-I-containing lipoprotein subfractions.

High-density lipoprotein comprises two main types of lipoprotein particles: (1) those that contain apolipoproteins A-I and A-II, designated LpA-I:A-II, and (2) those that contain apolipoprotein A-I but not apolipoprotein A-II, designated LpA-I. Both have been extensively studied and are believed to represent distinct metabolic entities that may confer differing protection against coronary artery disease risk. We have previously suggested that LpA-I might represent the antiatherogenic effect, which has been ascribed mainly to its effect on high-density lipoprotein cholesterol; we set out to investigate, in 344 men, the relation between LpA-I:A-II and LpA-I levels and alcohol consumption. As the alcohol intake rose, LpA-I:A-II levels increased, while LpA-I levels fell. On the assumption that LpA-I is the antiatherogenic fraction of high-density lipoprotein, the putative protective action of alcohol consumption against coronary artery disease should be reconsidered.

Human apolipoprotein B. Evidence for its immunochemical heterogeneity using monoclonal antibodies and an immunoenzymometric assay.

Predefined monoclonal antibodies (Mabs) were used in an immunoenzymometric assay to study the immunochemical heterogeneity of lipoproteins and to search for potential epitopes with pathological importance. By measuring apolipoprotein B (apo B) epitopes in patients with and without angiographically documented coronary artery disease and in patients with type IIa hyperlipoproteinemia, we have found that both types of patients have a significant increase in Apo B-containing particles specifically recognized by one Mab (BL3). We have also observed that the effects of fenofibrate on type IIa patients vary greatly depending on the plasma concentrations of various Apo B-containing lipoproteins. The greatest effects occurred in patients with epitopes recognized by BL3. Lastly, by sequential precipitation of specific epitopes by BL3, we have obtained evidence that the residual epitope(s) may be related to one or more lipoprotein particles.

Variations in lipoproteins during aminoglutethimide therapy.

Plasma lipids, apolipoproteins, and gamma-glutamyl-transpeptidase (GGT) were measured in 28 patients receiving aminoglutethimide (500 mg) and hydrocortisone (30 or 40 mg) for advanced breast cancer. A rise in cholesterol (CHOL), LDL-CHOL, apoprotein B, apoprotein CIII, and GGT was observed after 45 days. When the patients were divided in two groups according to lipid basal plasma levels, those with high CHOL and triglyceride did not experience any modification of lipid parameters (only GGT were elevated). Conversely normolipidaemic patients experienced an increase in CHOL, triglycerides, LDL-CHOL, apoproteins B and CIII, and GGT.

[Multivariate analysis of biological markers of excessive consumption of alcohol. Value of lipoprotein parameters]. / Analyse multivariée d'indicateurs biologiques de consommation excessive d'alcool. Intérêt des paramètres lipoprotéiques.

In order to investigate the usefulness of lipid, lipoprotein and apolipoprotein parameters for detection of intemperate drinkers, 90 adult male subjects with an alcohol consumption above 400 g weekly were compared to 90 matched (age, body weight index) male subjects with an alcohol consumption below 250 g weekly. GGT and MCV were also evaluated. Univariate analysis showed GGT, apolipoprotein A-II and phospholipid-LP no B levels to be parameters the most significantly different between drinkers and controls. Discriminant analysis using six parameters in addition to apolipoprotein A-II allowed to classify correctly 80% of subjects (efficacy) with respect to their alcohol consumption. However, sensitivity of the parameters remains relatively low and a good efficacy is obtained only with a composite index of several parameters.

Black-white differences in serum Lp(a) lipoprotein levels.

Serum Lp(a) lipoprotein was determined in 81 black and 81 white healthy men and women matched for sex and age. The results show a highly significant increase of Lp(a) concentrations in blacks as compared to whites, and confirm the notion that Lp(a) lipoprotein levels are race-dependent. Whether high values of Lp(a) play an atherogenic role in blacks remains to be established in further studies.

Detection of human apolipoprotein B polymorphic species with one monoclonal antibody (BIP 45) against low density lipoprotein. Influence of this polymorphism on lipid levels and coronary artery stenosis.

The immunoreactivity of apolipoprotein B (apo B) in plasma samples obtained from a variety of subjects was analysed by non-competitive ELISA with a polyclonal and a monoclonal (BIP 45) anti-LDL antibody. Three populations were tested: the first, comprising 244 healthy male volunteers, provided reference values; the second consisted of a population undergoing coronary angiography (n = 88) and was divided into a subgroup with (n = 64) and without (n = 24) coronary artery disease (CAD); the third was made up of 56 patients with heterozygous familial hypercholesterolemia. Total apo B (measured with the polyclonal antibody) was increased in the populations with CAD and in the heterozygous familial hypercholesterolemic subjects compared to the reference population. When monoclonal antibody BIP 45 was used in the non-competitive ELISA, three different patterns emerged in each population, corresponding to weak, intermediate and strong binding of the particles containing apo B to the monoclonal antibody. This may result from genetic polymorphism of apo B, and in the reference population the data fit a model consisting of two co-dominant apo B alleles (BIP(-) and BIP(+]; the 3 subpopulations then correspond to the 2 homozygotes and the heterozygote. The number of patients whose particles bound weakly to monoclonal BIP 45 antibody was low in the CAD population, while intermediate binding was increased in this group. Nevertheless, when the analysis of variance of allele BIP(-) was studied no significant difference between groups was established. This finding indicates that the genetic difference in apo B detected by BIP 45 may not be significant in the development of CAD. Furthermore, the apo B genetic polymorphism detected by BIP 45 is not associated with a particular lipoprotein level in the reference population.