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Biomedical subjects

M Rosseneu

Publications and source records attributed to M Rosseneu.

At least 181 records · Page 10Linked to original sources
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↗
PubMed1981

Lipid and apoprotein levels in myocardial infarction survivors. A case-control study.

Serum cholesterol (TC), Triglycerides (TG), high density lipoprotein (HDL) cholesterol and the apoproteins A1 and B were determined in 20 males survivors of myocardial infarction and in 20 healthy age and sex matched controls. HDL-C, HDL-C/TC and apo B/apo A1 were significantly different between the two groups. In a multivariate statistical analysis 85% of all subjects were correctly classified by using the HDL-C/TC and the apo B/apo A1 ratio. This study indicates that the apoproteins quantification yield complementary information in discriminating young male myocardial infarct survivors from normal controls.

Adult↗
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↗
PubMed1980

Evolution of lipoprotein patterns in newborns.

The plasma levels of total and high-density lipoprotein cholesterol and of the major apolipoproteins (apo B and apo A-I) were studied in 30 newborns, on cord blood and after 7 and 30 days of life. The evolution of these parameters during the first month of life shows that newborns have low LDL cholesterol and apo B levels at birth, which increase drastically during the first week and remain constant between 7 and 30 days. The HDL cholesterol and apo A-I levels are proportionally high at birth and keep increasing slowly up to 30 days. During this period, the cholesterol/apoprotein ratio remains constant in the LDL and HDL class. These data suggest that lipid and apoprotein levels at 7 days are more representative than cord-blood levels and more meaningful for a screening of congenital hypercholesterolemia. The cholesterol/apo B and apo B/apo A-I ratios, which are considered to be better predictive factors for atherosclerosis, should be included as screening parameters.

Apolipoproteins↗
PubMed1979

Fluorescence depolarization studies and phase transition in human apoprotein . phospholipid complexes.

The microviscosity of unilamellar vesicles of dimyristoyl-3-sn-phosphatidylcholine and that of phosphatidylcholine . apoprotein complexes was followed by fluorescence depolarization after labeling with 1,6-diphenyl-1,3,5-hexatriene. The transition temperature from gel-crystalline to liquid-crystalline phase in 24 degrees C for the dimyristoyl-phosphatidylcholine vesicles and is shifted to around 30 degrees C in the complexes between phosphatidylcholine and apoA-I, apoA-II, apoC-I, apoC-III proteins while the cooperativity of the transition is decreased. At temperatures below the transition of the phospholipid, the microviscosity of the complexes of phosphatidylcholine with apoA-I, apoA-II and apoC-I proteins is lower than that of the phosphatidylcholine, while the opposite effect is observed above 30 degrees C. The phosphatidylcholine . apoprotein complexes isolated on a Sepharose 6B column have a molecular weight around 100 000 and a phosphatidylcholine/apoprotein ratio of 2--2.6 (w/w). The microviscosity measurments at 35 degrees C performed after elution of the column enable the complex to be detected. The size and microviscosity of the apoprotein . phosphatidylcholine complex is compatible with a model where the vesicular structure has disappeared and the amino acid side chains present hydrophobic interaction with the phosphatidylcholine acyl chains.

Apolipoproteins↗
PubMed1979

Influence of oral polyunsaturated and saturated phospholipid treatment on the lipid composition and fatty acid profile of chimpanzee lipoproteins.

The influence of treatment with polyunsaturated lecithin (EPL) and with saturated lecithin on the lipoprotein composition and fatty acid profile was investigated in 4 male chimpanzees. The animals were successively given 3 isocaloric diets containing the same amount of fat with a degree of saturation varying from 1 in the control diet to 0.2 in the diet enriched with polyunsaturated lecithin, to 4 in the diet enrich with saturated lecithin. The VLDL, LDL and HDL3 fractions were isolated by ultracentrifugal flotation; changes in their lipid and fatty acid composition were followed and their microviscosity was measured. The treatment with polyunsaturated lecithin increases the cholesterol esters and lysolecithin content in HDL3, presumably via activation of the enzyme LCAT. These modified HDL particles have a more fluid surface and a denser core and are susceptible to act as better cholesterol carriers. A complementary effect of this treatment is a decrease of the plasma triglycerides and VLDL concentration, an increase in the unsaturation ratio of the triglycerides which might take place via activation of triglyceride lipase. The saturated lecithin treatment increases the plasma VLDL and LDL concentrations and the triglyceride levels and increases mostly the saturation ratio of the cholesterol esters. These effects are likely to enhance the progression of atherosclerosis.

Administration, Oral↗
PubMed1978

A simple screening method for plasma lipids by thin-layer chromatography with flame ionization detection.

Thin-layer chromatography was carried out on glass rods coated with Silica gel (chromarod) and the fractions were detected with a flame ionization detector (FID). This system was applied to the fractionation and screening of plasma lipids. As the relative response of the flame ionization detector depends on the nature of the lipids, correction factors had to be introduced. These correction factors were derived from comparison of the results of the thin-layer chromatography with flame ionization detection with those obtained by conventional chemical analysis of the same sample. The coefficients of variation of the lipid profiles were comparable for both techniques. The absolute lipid concentration for the various fractions obtained by combination of the concentration of the total lipids with the relative lipid profile, correlate very well with the values obtained by conventional chemical analysis of the various lipids.

Cholesterol↗
PubMed1977

Ionization behaviour of native apolipoproteins and of their complexes with lecithin. 1. Calorimetric and potentiometric titration of the native apoA-I protein and of the apoA-I protein-dimyristoyl lecithin complex.

The ionization behaviour of native apoA-I protein is compare to that of its complex with synthetic dimyristoyl lecithin in studies using calorimetric, potentiometric and spectrophotometric titration. In the presence of phospholipids, 10 out of 21 lysines together with 22 acidic residues are masked in the complex. All tyrosines remain accessible to titration below pH 13. The apparent ionization enthalpy of the 11 lysine residues is not affected by the presence of phospholipids. These data are consistent with discrete binding sites located in the apoprotein helical segments as suggested by the model of Segrest et al. [FEBS Lett. 38, 247-253 (1974)]. A tentative localisation of lysine, arginine, aspartic acid and glutamic acid residues directly involved in phospholipid binding is suggested, assuming that such helical regions are involved in apoprotein-phospholipid association.

Amino Acid Sequence↗
PubMed1977

Ionization behaviour of native apolipoproteins and of their complexes with lecithin. 2. Potentiometric titration of the native apo-A-II, apoC-I, apoC-III proteins and of their complexes with dimyristoyl lecithin.

A comparison of the ionization behaviour of the human apoA-II, apoC-I, apoC-III proteins and of their complexes with dimyristoyl lecithin is based on potentiometric titration of the basic and acidic residues and spectrophotometric titration of the phenolic groups. Experimental data suggest that a number of lysine, arginine, aspartic acid and glutamic acid residues are masked in the complexes. For each of these amino acids and in all three proteins the number of masked residues is consistent with the content of those regions predicted to be involved in lipid binding by the model of Segrest et al. [FEBS Lett. 38, 247-253 (1974)]. These data taken together with the results of calorimetric and titration experiments with the apoA-I protein reported in the accompanying article [Rosseneu et al. (1977) Eur. J. Biochem. 79, 251-257] strongly support the general nature of the proposed model and further suggest that ionic interactions have some role in the formation of the dimyristoyl lecithin/apolipoprotein complexes.

Amino Acid Sequence↗
PubMed1977

Thermodynamics of lipid protein associations. Thermodynamics of helix formation in the association of high density apolipoprotein A-I (apoA-I) to dimyristoyl phosphatidylcholine.

The structure and phospholipid-binding properties of human plasma high density apolipoprotein A-I (apoA-I) has been studied at pH 7.4 and 3.1 by microcalorimetry, circular dichroism and density gradient ultracentrifugation. At pH values of 7.4 and 3.1, apoA-I binds to dimyristoyl phosphatidylcholine (DMPC) to form complexes of similar composition (molar ratio of DMPC/apoA-I of 100) and helical content (67%). At pH 7.4, the lipid-protein association is accompanied by an increase in helical content from 58 to 67% and an exothermic enthalpy of binding (deltaHB) of -90 kcal/mol apoA-I. At pH 3.1, the helical content of apoA-I is increased from 48 to 67% on binding to DMPC and the enthalpy of binding was -170 kcal/mol. We suggest that the difference in the enthalpies of binding (-80 kcal/mol) at pH 3.1 compared to 7.4 is due to the greater coil leads to helix transition at the lower pH.

Apolipoproteins↗
PubMed1977

Characterization of baboon plasma high-density lipoproteins and of their major apoproteins.

Baboon high-density lipoproteins (HDL) were isolated by preparative ultracentrifugation between d = 1.063 and 1.215 g/mL. The HDL contains 48.8% protein and a lipid distribution similar to human HDL. The phospholipid distribution shows a low sphingomyelin value (5.9%), and the fatty acid composition of HDL is comparable to the human data except for the 18:1/18:2 ratio as a result of a higher 18:1 content in the CE and a lower 18:2 concentration in the PL. The major HDL apoproteins isolated on diethylaminoethyl-cellulose had a mobility on sodium dodecyl sulfate--polyacrylamide gel electrophoresis and a molecular weight and an amino acid composition similar to human apoA-I. However, the amino acid sequence of the first 30 residues of baboon apoA-I differed from the human apoprotein in residues 15 and 21. Treatment of apoA-I with carboxypeptidase A indicated a carboxyl-terminal sequence of Leu-Ser-Thr-Gln. Baboon apoHDL contained monomeric apoA-II with the mobility of monomeric human apoA-II and a molecular weight of 8500. The amino acid composition differed from the human apoA-II by the presence of arginine and by the absence of half-cystine and isoleucine. The circular dichroic spectra of apoA-I and apoA-II demonstrated a higher helicity compared to the human apoproteins. Recombination studies by microcalorimetry of apoHDL with dimyristoylphosphatidylcholine (DMPC) indicated similarities in the thermodynamic binding properties of the HDL apoproteins from man and baboon. The maximal-binding enthalpies of DMPC to apoHDL, apoA-I, and apoA-II were lower for the baboon than for the human apoprotein.

Amino Acids↗
PubMed1977

Phospholipid binding and self-association of the major apoprotein of human and baboon high-density lipoproteins.

The purpose of this study was to establish a relationship between self-association and phospholipid binding of the human and the baboon apoA-I protein. The enthalpy changes on binding dimyristoyl lecithin and lysolecithin to either the human or the baboon native apoA-I protein were measured in a microcalorimeter. An endothermal process, most pronounced for the human apoprotein, was observed at low phospholipid levels. At higher phospholipid to protein ratios the binding was exothermal. Gel filtration experiments on Sephadex G-200 showed that the native apoprotein of both species consists of dimers and tetramers. The baboon native apoA-I protein contained a higher amount of dimers. After preincubation of the apoA-I protein with lysolecithin, the enthalpy changes measured on subsequent binding of dimyristoyl lecithin were shifted towards more exothermal values compared to the curve for the native apoprotein. The amplitude of this shift corresponds to that of the endothermal process observed on binding dimyristoyl lecithin to the native apoprotein. This process was attributed to a phospholipid-induced disaggregation of the apoA-I protein. Gel filtration data showed a decreased extent of aggregation in the apoA-I protein preincubated with lysolecithin. This sample consisted exclusively of dimers. Ultracentrifugal flotation of the complexes formed between the apoA-I protein, and respectively dimyristoyl lecithin and sphingomyelin indicated that preincubation with lysolecithin increased the extent of complex formation. These results suggest that the dimeric form of the apoA-I protein possesses the highest affinity for phospholipids. Any dissociation of higher polymers enhances the phospholipid-binding capacity of the human and the baboon apoA-I protein.

Animals↗
PubMed1976

Interaction of the apoproteins of very low density and high density lipoproteins with synthetic phospholipids.

The interaction of synthetic dimyristoyl phosphatidylcholine (lecithin) liposomes with isolated apoC-I and apoC-III proteins from very low density lipoproteins has been studied by microcalorimetry. Complex formation is a highly exothermal process characterized by a maximal enthalpy of -130 kcal/mol (-544 kJ) apoC-III-1 and -65 kcal/mol apoC-I proteins (-272 kJ). The complex composition determined after its isolation by ultracentrifugal flotation agrees with the value derived from the enthalpy binding curves. The binding of a constant amount of dimyristoyl lecithin to apoprotein mixtures containing various proportions of apoA-I and apoC-III failed to demonstrate the existence of any preferential association between the two apoproteins, in contrast with results obtained previously with apoA-I/apoA-II protein mixtures. Finally the various contributions to the enthalpy of binding such as that arising from an increase in apoprotein helicity have been evaluated. A classification of the apolipoproteins according to their lipid-binding affinity is proposed as: apoA-II congruent to apoC-III greater than apoC-I greater than apoA-I proteins.

Apolipoproteins↗
PubMed1976

Study of the lipid binding characteristics of the apolipoproteins from human high density lipoprotein. I. Electron microscopic and gel filtration studies with synthetic phosphatidylcholines.

The characteristics of the lipid - protein complex produced by the addition of the major apolipoproteins (apo AI and apo AII) of human high-density lipoprotein to synthetic phospholipids has been studied. Under the in vitro conditions utilized, apo AI binds to 1,2-dimyristoyl-sn-glycerophosphocholine and 1,2-dipalmitoyl-sn-glycerophosphocholine liposomes, but does not alter their morphologic characteristics. This binding occurs at temperatures above or below that of the transition (Tt) of the lipid bilayer. In contrast, apo AII spontaneously generates small, homogeneous disc-shaped lipid-protein complexes (50 X 10 a) from large phospholipid globules or from liposomes prepared with these lipids. This type of complex was only formed when the lipid/apo AII mixtures were warmed above the transition temperatures. The incorporation of apo AI into this small complex with apo AII may be greatly facilitated or inhibited depending on the sequence of addition of the various components. Under optimal circumstances, a maximum of 1 molecule of apo AI is incorporated with each molecule of apo A II into complexes with these two synthetic phospholipids.

Apoproteins↗