Biomedical subjects
Publications and source records attributed to J C Fruchart.
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.
Electron microscopic examination of the interaction of gold labelled HDL with platelets indicates that the internalized lipoprotein becomes closely associated with surface connected canaliculae and endocytic vacuoles. At the same time granule centralization occurs. Using fluorescent derivatives of naturally occurring lipids we have further investigated lipid exchange between HDL and platelets. Analogs of phosphatidylcholine containing fluorescent fatty acids are rapidly transferred from the lipoproteins to the cells and remain at the plasma membrane as long as they are kept at 4 degrees C. However when the platelets are warmed to 37 degrees C, a rapid degradation of the fluorescent lipids occurs, generating fluorescent diacylglycerol as a consequence of the activation of platelet enzymes.
A non-competitive enzyme linked immunosorbent assay (ELISA) has been developed to quantitate apolipoprotein E (Apo E) concentrations in serum and in isolated lipoproteins. Microtiter plates coated with affinity-purified antibodies to Apo E were used and the Apo E bound to the plates was estimated with peroxidase-labelled antibodies to Apo E. The average concentration of Apo E in the serum from normolipidemic subjects (n = 132) was 54 +/- 19 mg/l. The within and between assay coefficients of variation were 4.65 and 7.08%, respectively. The standard curves for Apo E in serum, in VLDL and in HDL were parallel. There was a good correlation (r = 0.81) between estimation of Apo E by our assay and that by electroimmunoassay. Assay sensitivity (1 ng of Apo E) was sufficient to enable a study of the distribution of Apo E in plasma lipoproteins separated by density gradient ultracentrifugal fractionation.
This paper describes a procedure for the rapid isolation of urea-soluble apolipoproteins (apo) from delipidated human very-low- and high-density lipoproteins using anion-exchange fast protein liquid chromatography. The separation was complete within 30 min and peaks corresponding to apolipoproteins A-I, A-II, C-I, C-II, C-III0, C-III1, C-III2 and E were identified by comparing their chromatographic, electrophoretic and immunological behaviour with that of purified standards of each protein. A second purification step is necessary to obtain pure apolipoproteins. Apo E, which is difficult to purify by conventional chromatography, has been obtained in a good yield. The apo C-II that was obtained produced a symmetrical peak on chromatography but three bands in isoelectric focusing. The method can be upgraded to a preparative scale and offers the possibility of direct purification of apolipoproteins both from high-density lipoproteins and (following preliminary gel chromatography) from very-low-density lipoproteins.
Cholesterol efflux was studied in cultured adipose cells after preloading with LDL cholesterol. Long-term exposure to LpAI and LpAI:AII particles isolated from the HDL fraction showed that LpAI particles only were able to promote cholesterol efflux. Liposomes containing different ApoAI/ApoAII molar ratios were tested: the larger the proportion of ApoAI, the faster the ability to remove cholesterol from Ob1771 cells. Dose-response curves showed that LpAI particles were active within a physiological range of concentrations, whereas LpAI:AII particles had no effect at all concentrations. The results are in favour of LpAI particles being the active components of the HDL fraction for the promotion of cholesterol efflux and suggest that LpAI particles and LpAI:AII particles represent distinct metabolic entities.
This paper describes the structure of acylcerebrosides isolated from rat brains. Three fractions (acylglycosylceramides I, II, III) were resolved according to their decreasing RF values on TLC. GLC analysis of acylglycosylceramides II and III indicates that their ester-linked fatty acids are short and rather unsaturated, while amide-linked fatty acids are longer and hydroxylated. Sugar GLC analysis indicates that acylglycosylceramides II and III contain only galactose. To determine the substitution position of the acyl group on the galactose moiety, the free hydroxyl groups of acylglycosylceramide were protected with dihydropyran, deacylated and subjected to permethylation. The methylated galactoside acetates obtained after hydrolysis and reduction were then analyzed by gas chromatography/mass spectrometry. Acylglycosylceramides II and III turned out to be complex mixtures of 2-O-acyl-, 3-O-acyl-, 4-O-acyl- and 6-O-acylgalactosylceramides. Moreover, the abundance of alpha-methylgalactoside reveals the existence of unsubstituted galactose, suggesting that some ester-linked fatty acids could be esterified to the hydroxyl group of hydroxy fatty acids linked to sphingosine. NMR spectrometry was used to confirm this ester linkage. The key spectral feature of the fatty acid-galactose linkage (4.45 ppm) did move to 4.15 ppm after saponification of acylglycosylceramide II; on the other hand, acylglycosylceramide III contained only the spectral feature 4.15 ppm, corresponding to a high percentage of unsubstituted galactose and consistent with the presence in the molecule of a fatty acid esterified by the omega-OH group of the hydroxy fatty acid (3.95 ppm).
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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.
At least 2 main types of lipoprotein particles are identified within HDL. Those which contain apo A-I and apo A-II (LpA-I:A-II) and those which contain apo A-I but not apo A-II (LpA-I). This study was designed to elucidate to what degree the HDL cholesterol decrease observed in coronary artery disease affects these 2 types of lipoprotein particles. Concentrations of LpA-I:A-II and LpA-I were measured in plasma from 100 normolipidemic male subjects with angiographically defined coronary artery disease (CAD(+)) or without CAD (CAD(-)) and from 50 control subjects, matched for age. CAD(+) subjects had significantly lower levels of HDL cholesterol, total apo A-I, and LpA-I than controls. When compared to CAD(-) subjects, only their levels of HDL cholesterol and LpA-I were found lower. In both cases (CAD(+) vs CAD(-) and CAD(+) vs controls), LpA-I levels were decreased while LpA-I:A-II levels were unchanged. Even, when the levels of their total plasma lipids and lipoproteins are normal, atherosclerotic patients are characterized by a different distribution of apo A-I between LpA-I and LpA-I:A-II. These data support the view that LpA-I might represent the "antiatherogenic" fraction of HDL.
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Serum concentrations of total cholesterol and lipoprotein cholesterol, of apolipoproteins A I and A II and of apolipoprotein A I in lipoprotein particles (Lp A I and Lp A) were determined in 43 patients with multiple myeloma. There were striking alterations in the plasma levels of these analytes relative to normal subjects. We observed a decrease of cholesterol levels in LDL, HDL and HDL3 fractions, and of apolipoproteins A I and A II compared with normal subjects. The HDL2 cholesterol was increased. The decrease of apolipoprotein A II was more prominent than apolipoprotein A I. The decrease of apolipoprotein A I concerns only the A I (Lp A), while the A I (Lp A I) was increased. Most of these modifications were correlated with the monoclonal Ig levels.
For the standardization of human plasma apolipoprotein A-I assay two well characterized monoclonal antibody mixtures were used to develop a sandwich immunoenzymometric assay. The monoclonal antibody mixture 1 (A05-A17-A30) in solid phase technique was selected on the basis of its higher binding capacity of [125I]HDL (41 ng per well) compared to polyclonal antibody (23 ng per well). The epitopes recognized by monoclonal antibody mixture 1 are surface antigenic sites of apolipoprotein A-I expressed on native HDL as determined by competitive inhibition of labeled HDL. The peroxidase conjugated monoclonal antibody mixture 2 (A03-A05-A17-A51) was selected on the basis of its ability to bind to apolipoprotein A-I captured by monoclonal antibody mixture 1. For this, we used the 125I-labeled monoclonal antibodies. Under optimized assay conditions, the immunoenzymometric assay is precise (intra- and inter-assay coefficients of variations 5.4% and 9.2% respectively). It yields plasma apolipoprotein A-I values that correlate highly with those obtained with polyclonal antibody (r = 0.96). So the use of well characterized monoclonal antibody mixtures reacting only to surface antigenic sites of apolipoprotein A-I present on native lipoprotein may provide the possibility of standardization of apolipoprotein A-I measurement.
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We describe a method for measuring apolipoprotein A-I (ApoA-I) associated and unassociated with apolipoprotein A-II (ApoA-II) in plasma. To directly determine associated ApoA-I, we coated microtiter plates with antibody to ApoA-II, blocked the nonspecific binding sites, and incubated the plate with plasma, immobilizing the lipoprotein particles containing both ApoA-II and ApoA-I. The unbound constituents of plasma were washed away, peroxidase-labeled antibody to ApoA-I was added, the plate rewashed, peroxidase substrate added, and the resulting color measured. ApoA-I unassociated with ApoA-II was evaluated by subtracting the concentration of associated ApoA-I from the total ApoA-I concentration. The method is specific, rapid, and precise. Within- and between-assay CVs were 5.6 and 9.8%, respectively. Analytical recovery of ApoA-I was 94%. The average normolipidemic concentration of ApoA-I associated with ApoA-II in 50 women was 790 mg/L; in 50 men, it was 788 mg/L. The corresponding values for unassociated ApoA-I were 644, 577 mg/L. Both lipoprotein forms of ApoA-I were detected in all major density classes, but were most abundant in high-density lipoproteins. The technique is applicable to measurement of any two apolipoproteins that occur in both associated and unassociated forms in plasma.
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.
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A solid phase enzyme-linked immunoassay based on the 'sandwich' principle was developed for quantitative measurement of apolipoprotein B (Apo B) in human normal or hyperlipoproteinemic sera. The solid phase (polypropylene multi-finned sticks) coated with an excess of sheep anti-Apo B immunoglobulins was incubated with antigen (standards and unknown specimens) and affinity-purified anti-Apo B antibodies conjugated with horseradish peroxidase. In this principle, antigen and conjugate were in excess and fixed amount respectively. A part of antigen was fixed on multi-finned sticks, bound or not to conjugate. Unbound materials were removed by washing. Solid phases were next incubated with the enzyme substrate solution to develop a color which is inversely related to the amount of Apo B. The best technical conditions for the assay were determined. The method was characterized according to precision, sensitivity and accuracy. It yielded values that compared favorably with those obtained by another enzyme-linked immunoassay and by electroimmunoassay.