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R Vercaemst

Publications and source records attributed to R Vercaemst.

At least 19 recordsLinked to original sources
PubMed2001

Serum alpha-tocopherol and selenium in Belgian infants and children.

Previous studies showed low selenium (Se) concentrations in Belgian children. Serum alpha-tocopherol, retinol, total cholesterol, high-density lipoprotein and low-density lipoprotein cholesterol, selenium (Se), and thiobarbituric acid-reactive substances were examined. In order to obtain further information on the Se status in Belgian children, Se, alpha-tocopherol, retinol, and lipid concentrations were examined and signs of peroxidative lipid damage were evaluated in a subgroup. The study was performed in 524 children (0-14 yr old) during vaccination campaigns. Three age groups were analyzed: 0-1, 1-4, and 4-14 yr. In 87 of them, where sufficient amounts of serum were available, analysis of thiobarbituric acid-reactive substances was done. Infants have high serum alpha-tocopherol concentrations: (23.2 micromol/L [median and interquartile range: 18.6-30.2]) and low Se concentrations (0.37 mol/L [0.27-0.47]). Se concentrations rise significantly during the first 4 yr (p < 0.0001) (Mann-Whitney U-test, tied p-values): 0.70 micromol/L (0.59-0.82); in the 4-14 yr olds, it was 0.75 micromol/L (0.67-0.86). These values remain low compared to results coming from other parts of the world. Alpha-tocopherol concentrations decrease significantly after infancy (p < 0.0001). The ratio alpha-tocopherol/total cholesterol is higher in infants. This is induced by the high vitamin E content of infant formulas. Signs of serum lipid peroxidation could not be detected by analysis of serum malondialdehyde concentrations. High alpha-tocopherol concentrations, as those observed in infant serum lipids, could be one of the protective mechanisms from the peroxidative lipid damages, sometimes observed in a low-Se status.

Adolescent↗
PubMed1992

Serum cholesterol, cholesteryl ester, and high-density lipoprotein development in newborn infants: response to formulas supplemented with cholesterol and gamma-linolenic acid.

Healthy newborn infants were either breast-fed or randomly designated to receive a standard formula, formula plus cholesterol, or formula plus gamma-linolenic acid at birth. At 0, 7, and 30 days of life, the following variables were measured: cholesteryl esters (cholesteryl arachidonate, cholesteryl oleate, cholesteryl palmitate, and cholesteryl linoleate), high-density lipoprotein (HDL) cholesterol, apoproteins (A-I, A-II, B, C-II, C-III, and E), and the cholesterol and apoprotein A-I content of the HDL subfractions HDL-2b, HDL-(2a + 3a), and HDL-(3b + 3c). Breast-fed infants had higher serum levels of cholesterol, cholesteryl oleate, cholesteryl palmitate, cholesteryl arachidonate, and HDL-2b than had formula-fed infants. Addition of gamma-linolenic acid to formula raised cholesteryl-arachidonate levels, and cholesterol and gamma-linolenic acid raised serum HDL-2b levels compared with those produced by unsupplemented formula. Our data suggest that both exogenous cholesterol and gamma-linolenic acid contribute to the maturation of HDL particles associated with human milk consumption in newborn infants. They may also promote adequate delivery of cholesterol and arachidonic acid to the developing brain.

Breast Feeding↗
PubMed1990

Determinants of fat consumption in a general population.

In a random sample of the adult population (aged 25-64 years) from Ghent and Charleroi in Belgium, dietary fat consumption was estimated using both qualitative and quantitative dietary methods. A fat consumption score (FCS) was constructed from the qualitative method, and it correlated significantly with the dietary polyunsaturated/saturated fatty acids (P/S) ratio calculated from the quantitative method (r = -0.48; p less than 0.001). Differences in FCS were then studied using univariate and multivariate analyses. In both men and women, FCS was higher in Charleroi than in Ghent. In men, FCS was inversely related with educational level and with age. In women, significant correlations were observed with marital status. No differences were found in FCS by smoking behaviour. With the coronary risk factors, low-order relationships were found, but only in men. In the middle-aged group, significant correlations were found between FCS and the fatty acid composition of the serum cholesteryl esters, in particular with the linoleate/oleate ratio.

Adult↗
PubMed1989

Separation and quantitation of free cholesterol and cholesteryl esters in a macrophage cell line by high-performance liquid chromatography.

A method for the direct high-performance liquid chromatographic (HPLC) determination of free cholesterol and the individual cholesteryl esters in cell culture experiments is described. The murine macrophage-like J774 cell line was loaded with cholesterol by incubation with low-density lipoproteins. After extraction of the cellular lipids with hexane-isopropanol (3:2, v/v), the cholesteryl esters were identified and quantified by isocratic HPLC. Unesterified cholesterol and its esters were eluted with acetonitrile-isopropanol (50:50, v/v) on a Zorbax ODS column within 25 min and detected at 210 nm. Cholesteryl heptadecanoate was used as an internal standard. The detection response is linear in the analytical range of interest; the overall coefficients of variation are less than 8% and the detection limit is between 50 and 150 ng. The results demonstrate that HPLC is suitable for the determination of cellular cholesteryl ester profiles and could usefully contribute to the understanding of the mechanism of foam cell formation during the development of atherosclerosis. This method can also be applied to all experimental systems involving the study of cholesteryl esters.

Animals↗
PubMed1989

Relationship between serum cholesteryl ester composition, dietary habits and coronary risk factors in middle-aged men.

Serum cholesteryl palmitate, oleate, linoleate and arachidonate were measured using high performance liquid chromatography in 134 men aged 45-64 years, randomly selected from the population of Ghent, Belgium. No relationship was observed between these cholesteryl esters, expressed as a percentage of their total, and age, serum cholesterol, arterial blood pressure, smoking habits and body mass index. Dietary habits were assessed using a 3-day diary method. No relationship was found between dietary habits and serum lipids. Highly significant correlations were observed between diet and the serum cholesteryl esters. In multivariate analyses dietary variables account for significant proportions of the variances of the serum cholesteryl esters. The results indicate that measurements of cholesteryl esters can be used to differentiate on the population level between subgroups with different dietary habits particularly with respect to fat consumption.

Age Factors↗
PubMed1989

Quantitation of plasma free cholesterol and cholesteryl esters by high performance liquid chromatography. Study of a normal population.

We describe a convenient method for the separation and quantitation of plasma free cholesterol and cholesteryl esters by high performance liquid chromatography (HPLC). After extraction of 100 microliters plasma with isopropanol the plasma cholesteryl esters were resolved on a Zorbax ODS reversed-phase column by isocratic elution with acetonitrile/isopropanol (50:50, v/v). Baseline separation of the plasma cholesteryl esters including the internal standard was obtained within a 25-min run. The intra- and interassay CV was less than 4%. The results obtained by HPLC show good agreement with enzymatic and gas-liquid chromatographic methods. High performance liquid chromatography provides a simple method for the quantitation of individual cholesteryl esters avoiding tedious chromatographic and derivatisation steps inherent to GLC. Our HPLC method was applied to the monitoring of plasma cholesteryl esters in a normal population and can also be used for the study of cholesteryl esters from lipid extracts of biological samples.

Adult↗
PubMed1989

[Determinants of fat consumption in a general population].

In a random sample of the adult population (aged 25-64 yr) from Ghent and Charleroi in Belgium, dietary fat consumption was estimated using both qualitative and quantitative dietary methods. A fat consumption score (FCS) was constructed from the qualitative method and correlated significantly with the dietary P/S ratio calculated from the quantitative method. Differences in FCS were then studied using univariate and multivariate analyses. In both men and women FCS was higher in Charleroi than in Ghent. In men FCS was inversely related with educational level and with age and positively related with BMI. In women no significant correlations were observed. In the middle-aged group (aged 45-64 yr) significant correlations were found between FCS and the fatty acid composition of the cholesterol-esters, in particular with the linoleate/oleate ratio.

Adult↗
PubMed1986

Apolipoprotein E quantified by enzyme-linked immunosorbent assay.

We developed a sensitive, specific "sandwich"-type enzyme-linked immunosorbent assay in which affinity-purified antibodies are used for coating and also for preparing an antibody-peroxidase conjugate to quantify apolipoprotein E in serum and in its lipoprotein fractions. This technique is rapid (results within 5 h), precise (mean intra- and interassay CVs 4.3 and 8.2%, respectively), accurate, and simple to perform. Sample pretreatment did not enhance apo E immunoreactivity. For 47 normolipidemic subjects, the mean apo E concentration was 38.11 (SD 11.1) mg/L. Above-normal apo E concentrations were measured in all types of hyperlipoproteinemia, especially types III and V. Apo E correlated with triglyceride (r = 0.58) and cholesterol concentrations (r = 0.60). As determined by gel filtration, hypertriglyceridemia was associated with a redistribution of apo E towards the triglyceride-rich lipoprotein fractions, which contained 77.1% (SD 16.8%) of total plasma apo E in Fredrickson type V patients, compared with 12.5% (SD 6.3%) in normal persons.

Antibody Formation↗
PubMed1983

Some considerations of methodology and standardization of apolipoprotein B immunoassays.

Apolipoprotein B, the major protein component of very-low-density (VLDL) and low-density (LDL) lipoproteins in serum, is being widely measured in serum, to help assess risk of cardiovascular disease. Standardization has proven difficult because of the physical and immunochemical heterogeneity of LDL and VLDL, the masking of antigenic determinants of LDL and VLDL, the insolubility of apolipoprotein B, the instability of lipoprotein reference materials, and the multiplicity of analytical methods. Here we have examined the literature and collected current information from lipoprotein scientists to determine the problems--and the ways investigators have attempted to solve them--in preparation, storage, and use of standards and anti-apolipoprotein B sera, analytical procedures and reagents, and the nature of apolipoprotein B in serum. Standardization appears possible with development of stable reference materials that are applicable to the various analytical methods, controlled immunochemical reaction conditions, and establishment of a selected interim reference method for use as a point of reference.

Adult↗
PubMed1982

Separation of lipoproteins in newborn plasma using an Airfuge ultracentrifuge.

The isolation of lipoprotein fractions in newborn plasma was performed by ultracentrifugation in an Air-driven ultracentrifuge (Airfuge). The purity and recovery of the fractions was checked by quantitation of the apo A1 and B proteins in the supernatant and infranatant fractions, and by gradient gel electrophoresis in 4-30% polyacrylamide gels. The influence of the duration of the ultracentrifugal run, the temperature and method for recovery of the fractions were tested. Under optimal conditions pure VLDL fractions could be isolated at d = 1.006 milligrams, whereas VLDL + LDL isolated at d = 1.063 milligrams were contaminated with HDL and other plasma proteins. Isolation of total lipoproteins at d = 1.21 milligrams enabled recovery of 75% of total plasma lipoproteins, however strongly contaminated by other plasma proteins. These results indicate that the recovery and purity of the lipoprotein fractions isolated in the Airfuge are not comparable to the results obtained in a conventional preparative ultracentrifuge.

Apolipoprotein A-I↗
PubMed1982

Plasma apoproteins levels in chronic alcohol abuse.

The plasma lipid and apoprotein concentrations were monitored in a group of 12 patients with chronic alcohol abuse entering an abstinence program for 3 weeks. 6 of them had a normal liver function as expressed by the levels of liver enzymes gamma GT, GOT, GPT, while 6 had elevated plasma liver enzyme concentrations. None had evidence of either cirrhosis or alcohol hepatitis. Patients with abnormal liver enzymes had elevated HDL-cholesterol, apo AI and apo AII concentrations in plasma, with normal total cholesterol and apo 8 concentrations. In the group of patients with normal liver enzyme concentrations, the apoproteins and lipids did not significantly differ from the control group. In the course of the abstinence treatment a parallel decrease of apoproteins, HDL-cholesterol and liver enzyme concentrations was observed. The values normalized after 10-15 days. These data indicate that the effect of alcohol on the plasma apoprotein and lipids occurs mostly in the HDL fraction, that it correlates with the state of hepatic function and that it can be reversed by an abstinence treatment.

Adult↗
PubMed1981

Plasma apoprotein and lipid patterns in newborns: influence of nutritional factors.

In this study the plasma lipid and apoprotein concentrations have been assayed in 80 full-term newborns, at 0, 7 and 30 days of life, and the data have been analyzed as a function of the composition of the diet. The total cholesterol, HDL cholesterol, the apo A-I, A-II and B protein concentrations were followed in 4 groups of infants receiving respectively breast-feeding, adapted formulae I, II with a P/S ratio close to that of maternal milk and a formula III enriched with polyunsaturated fatty acids. After 7 and 30 days the infants receiving the adapted formulae I and II have plasma lipid and apoprotein values similar to those of the breast-fed infants indicating a parallel evolution of the lipids and apoproteins in the three groups. The lipid and apoprotein patterns were significantly different in the group of infants receiving a diet enriched with polyunsaturated fatty acids. The total and VLDL-LDL cholesterol and the apo B protein concentrations are significantly lower than in the breast-fed infants after 7 days, and these differences become more pronounced after 30 days. These results suggest that the fatty acid composition of the diet influences the lipid and lipoprotein synthesis in newborns, specially by decreasing the lipid and apoprotein concentrations of the VLDL-LDL fraction.

Apoproteins↗
PubMed1981

Quantitative determination of human plasma apolipoprotein A-I by laser immunonephelometry.

A technical procedure is described for quantitation of human apolipoprotein A-I (apo A-I) in normal plasma or serum by immunonephelometry. Dilution of the plasma samples with 6 mol/L guanidine chloride ensures maximum exposure of the antigenic sites of the apoprotein and enables optimum quantitation of the apo A-I without requiring extraction with organic solvents. Similar data are obtained by this assay and with radioimmunoassay for normal subjects (1.2--1.5 g/L), and the results obtained on 31 patients are correlated with a coefficient of 0.92. The apo A-I values are correlated with values for plasma high-density lipoprotein cholesterol (r = 0.64). The interassay CV for immunonephelometry is about 7% and the standard curve is linear between 0.1 and 1.0 microgram of apo A-I per sample, corresponding to a 150-fold dilution of serum or plasma. The assay is applicable to plasma samples containing as much as 4 g of triglycerides per liter. At higher concentrations plasma delipidation is required.

Adult↗
PubMed1981

Lipoprotein patterns in newborns. Influence of nutritional factors.

Plasma and apoprotein levels were assayed in 3 groups of newborns at 0, 7 and 30 days and analyzed as a function of the degree of fatty acid saturation of the diet. The levels of total and HDL cholesterol and the apo A-I, apo A-II and apo B proteins were quantitated in infants either breast-fed or given an adapted formula (I) with a P/S ratio close to that of mother's milk or a formula (II) enriched in polyunsaturated fatty acids. The lipid apoprotein levels are very similar in breast-fed infants and in those receiving the adapted formula I after 7 and 30 days. The addition of PUFA to formula II, significantly affects the plasma lipids and apoproteins of the infants after one week and one month of feeding, as total HDL cholesterol, apo A-I and apo B are significantly lower than in breast-fed infants. The results of this study therefore indicate that lipid and apoprotein synthesis in newborns is sensitive to the degree of fatty acid saturation of the diet. Plasma lipoprotein concentrations at 7 and 30 days are dependent on the type of nutrition.

Aging↗
PubMed1980

Reassembly of human apoproteins A-I and A-II with unilamellar phosphatidylcholine-cholesterol liposomes. Association kinetics and characterization of the complexes.

The kinetics of association between the human apoprotein A-I and apoprotein A-II and cholesterol dimyristoyl phosphatidylcholine (DMPC) vesicles are compared in this study and the lipid-apoprotein complexes are characterized. The association kinetics are followed by turbidity measurements monitoring the decrease of the vesicular size and by fluorescence polarization measurements monitoring the decrease in the mobility of the phospholipid acyl chains during complex formation. The influence of the incubation temperature and of the cholesterol/DMPC ratio has been studied by both techniques. Under all incubation conditions the apoprotein A-II associates more readily with cholesterol-DMPC vesicles than apoprotein A-I, as the kinetics are faster and the complex yield larger. With both apoproteins optimal complex formation takes place around the phospholipid transition temperature and around 10 mol% cholesterol. The apoprotein A-I/lipid association seems restricted to this narrow range for the temperature and the cholesterol/DMPC ratio, while the apoprotein A-II still associates with vesicles containing 20 mol% cholesterol and at temperatures up to 32 degrees C. The lipid-apoprotein complexes were isolated by gradient ultracentrifugation and by gel chromatography. According to these data the apoprotein A-II associates more readily than apoprotein A-I with cholesterol-DMPC vesicles to form protein-rich complexes, whilst the optimal apoprotein A-I-lipid association requires a more disordered lipid structure.

Apolipoprotein A-I↗