Plasma levels of VLDL- + LDL-cholesterol, HDL-cholesterol, triglycerides and apoproteins B and A-I in a healthy population--influence of several risk factors.

Plasma apo B and apo A-I were determined in 477 subjects (206 males and 271 females) by laser immuno-nephelometry. Measurements of VLDL- + LDL-cholesterol, HDL-cholesterol and triglycerides were done simultaneously. VLDL- + LDL-cholesterol and apo B values were similar in males and females and increased with age. HDL-cholesterol and apo A-I values were higher in females but stable with age. Different regression curves (HDL-cholesterol vs apo A-I) were obtained in males and females and a negative correlation was found between HDL-cholesterol or apo A-I and triglycerides. Increased body weight was associated with higher values of VLDL- + LDL-cholesterol, apo B and triglycerides in both sexes but lower values of HDL-cholesterol and apo A-I essentially in males. Finally, the study provides evidence of a relationship between smoking and alcohol consumption on the one hand, and HDL-cholesterol and apo A-I on the other.

Inhibition enzyme immunoassay, application to human apolipoprotein B.

Inhibition enzyme immunoassay was applied to human apolipoprotein B (apo-B) from plasma. The technical conditions of the assay were determined. The detection limits of the assay were 200 ng to 10 microgram/ml. Correlation coefficients obtained between enzymoassay and rocket immunoelectrophoresis on one hand and radial immunodiffusion on the other were respectively 0.84 and 0.80. The inhibition enzymoassay provides a specific and highly sensitive method for the quantitation of apo-B.

[Metabolic study of 3 lipid emulsions used parenteral feedings. I. Exploration in vivo in the minipig]. / Etude métabolique de trois émulsions lipidiques utilisées dans l'alimentation parentérale. I. Exploration in vivo chez le miniporc

The metabolism of three fat emulsions (Lipiphysan, Trive 1000, Intralipid) was compared when administered by intravenous route as complete parenteral nutrition in minipigs during 14 days. With Lipiphysan, an important accumulation of glycerides appeared in liver, spleen and lung whereas the phospholipids content of those tissues was unchanged. The three fat emulsions determined an increase of linoleic acid (18:2) percentages in glycerides and phospholipids of several tissues: liver, heart, lung, spleen and kidney. Moreover, at the level of phosphatidyl-ethanolamine (PE) in liver tissue, the three fat emulsions induced a decrease of some polyunsaturated fatty acids (C20 and C22) percentages. The observed differences in the amount of liver triglycerides between the three fat emulsions seem to be related with the removal mechanisms which appear to be dependent on each fat emulsion. In fact, all tissue lipid analyses showed an increase of 18:2 percentages which agree with an uptake of the different fat emulsions used. The decrease of polyunsaturated fatty acids percentages in PE might be due to an inhibition of elongationdesaturation system or a degradation of those fatty acids.

[Metabolic study of 3 fat emulsions for intravenous nutrition. II. Study by isolated rat liver perfusion]. / Etude métabolique de trois émulsions lipidiques utilisées dans l'alimentation parentérale. II. Etude par perfusion de foie de rat isolé

With a model of isolated rat liver perfusion, the authors study the removal kinetic of three different fat emulsions. In experiments done with Lipiphysan, triglyceride uptake by liver is linear with a rate of 30 mg/h until the 60th minute; after blockade of the reticuloendothelial system (RES), triglyceride uptake is greatly reduced. In standard experiments done with Intralipid and Trive 1000, triglyceride content of the perfusate does not vary significantly; however, the study of free fatty acids removal done before and after liberation of hepatic triglyceride lipase by heparin seems to show that Intralipid triglycerides are slightly hydrolyzed by hepatic triglyceride lipase. The particles of Lipiphysan might be capted directly by RES cells (fast removal), whereas Intralipid might be slightly hydrolyzed (slow removal); Trive 1000 removal appears to be slow and similar to Intralipid. Those results give some explanations on data obtained in vivo in minipigs and agree with a better use of Intralipid and Trive 1000 triglycerides by extrahepatic sites.

[Lipoprotein electrophoresis on acrylamide-agarose plates, with discontinuous acrylamide gradient]. / Electrophorese des lipoproteines seriques sur plaque de gel d'acrylamide-agarose, en gradient discontinu d'acrylamide.

We describe a modified lipoprotein electrophoresis on acrylamide gel. The lipoproteins, prestained with Sudan Black, are separated by running on acrylamide-agarose gels, with two different concentrations of acrylamide and a constant concentration of agarose. The sera are deposited in the first gel (2% acrylamide). Chylomicrons remain at origin and other lipoproteins run through the first gel to the second one (3% acrylamide gel). VLDL stays at the junction of both gels, LDL and HDL are separated in the 3% acrylamide gel. By this technique, we were able to detect an increase of Lp(a) and to identify the different types of hyperlipoproteinemia. After running, the plates can be treated for storage.

Immunochemical determination of human apolipoprotein B by laser nephelometry.

The Hyland laser nephelometer PDQ system for the assay of apolipoprotein B (apo-B) in human serum is described. Within and between-batch precision, accuracy and reliability are discussed. This instrument represents an important development in the immunochemical assay of apo-B, and the speed, precision, and convenience of the methodology make such a system attractive. Quantitation of apo-B was assessed in normal and hyperlipaemic subjects. Comparisons were made with two other specific and sensitive immunological methods for quantifying apo-B: enzymeimmunoassay (EIA) and rocket immunoelectrophoresis (RIE). Results obtained by the three methods correlated very well.

[Exact determination of the lecithin/sphingomyelin ratio in amniotic fluid. Suggestion of a reference methods (author's transl)]. / Determination precise du rapport lecithine/sphingomyeline dans le liquide amniotique: Proposition d'une methode de reference.

Pulmonary maturity of the fetus can be evaluated by the lecithin/sphingomyelin (L/S) ratio in amniotic fluid. To existing methods of lipid extraction, precipitation with acetone and chromatography, we add a simple and accurate estimation of sphingomyelins (S) and precipitated lecithins (Lp) without acid digestion. The method is reproducible (C.V. less than 9%) for the measurement of Lp/S ratio and gives with accuracy the concentrations of Lp, avoiding possible errors in interpretation of Lp/S. Our results show that at 35 weeks of normal gestation, Lp/S ratio is about 2 and Lp concentration, 10 mg/1.

Changes in rat heart phospholipid composition after rapeseed oil feeding.

The influence of long duration rapeseed oil feeding with high or low levels of erucic acid has been investigated on rat heart phospholipids. The rats treated for 20 wk with rapeseed oil containing 46.2% erucic acid showed a twofold increase in the sphingomyelin content of the heart. Treatment with primor rapeseed oil (3.7% erucic acid) for 20 wk did not modify phospholipid composition of rat heart. The fatty acid patterns of phosphatidylethanolamine and phosphatidylcholine were slightly influenced by the high erucic rapeseed oil; eicosenoic acid was incorporated preferentially into position one, but erucic acid showed a random distribution in both. After high erucic rapeseed oil feeding, 22:1 was incorporated into cardiolipin (5.6%) and sphingomyelin (10.5%). The incorporation of 22:1 into sphingomyelin was associated with an increase of the percentage of 24:1 (14.6%) and a decrease of saturated long chain fatty acid (22:0, 24:0) percentages. Primor rapeseed oil caused a slight increase of 24:1 and a decrease of 22:0 and 24:0 in rat heart sphingomyelin. As cardiolipin is localized in the inner membrane of mitochondria and sphingomyelin in plasma and microsomal membranes, the acyl-moiety alterations of both phospholipids might be correlated to the pathological lesions of rat heart after a long duration of rapeseed oil feeding.

Changes in fatty acid composition of cardiac mitochondrial phospholipids in rats fed rapeseed oil.

Male Wistar rats were fed rapeseed oil containing high or low levels or erucic acid for 20 weeks, and changes in the fatty acid composition of cardiac mitochondrial phospholipids were studied. Treatment with rapeseed oil containing 46.2% erucic acid showed incorporation of 22:1 (5.6%) into isolated cardiolipin from heart mitochondria. After high or low (3.7%) erucic rapeseed oil feeding, linolenic acid was slightly incorporated into cardiolipin. Moreover, both of these rapeseed oils induced a significant increase of linoleate-arachidonate ratio in phosphatidylethanolamine and phosphatidylcholine. This ratio was also significantly increased in fatty acids esterified to the beta-position of these phospholipids. On the basis of such results, we have to consider the role of linolenic acid which is present at a high level in the different rapeseed oils used, as a possible inhibitor of heart microsomal enzymes involved in linoleate arachidonate conversion. Such alterations might account for mitochondrial fragility and myocardial lesions obtained in long term rapeseed oil feeding experiments.

[Diagnosis of type III hyperlipoproteinemia: contribution of an air-driven ultracentrifuge associated with an original tube-slicer (author's transl]. / Diagnostic de l'hyperlipoprotéinémie de type III: apport d'une ultracentrifugeuse à turbine à air associée à un coupe-tube de conception originale.

Diagnosis of type III hyperlipoproteinemia requires preparative ultracentrifugation in order to measure the cholesterol/triglyceride molar ratio into isolated d less than 1.006 lipoproteins. The authors describe an ultracentrifugation micromethod which needs 600 microliter of serum and can be completed within three hours (Airfuge Beckman instruments). An original tube-slicer allows the separation of the d less than 1.006 lipoproteins located into top fractions. This simple micromethod might confirm diagnosis of type III in patients and would be useful for clinical laboratories.

[Analysis of lipoproteins using polyacrylamide gel electrophoresis and fractionated precipitation with polyanions and detergents. Use in the classification of hyperlipoproteinemias]. / Analyse des lipoprotéines par électrophorèse sur gel de polyacrylamide et par précipitation fractionnée à l'aide de polyanions et de détergents. Application au typage des hyperlipoprotéinémies

Sodium dodecylsulphate precipitates very low density lipoproteins (VLDL and chylomicrons) rich in triglyceride and a narrow correlation (r = 0.9) was found between the turbidimetric index SDS and triglyceridemia. Heparin in calcium medium acts in the same way and precipitates also low density lipoproteins (LDL) rich in cholesterol. A correlation (r = 0.875) was drawn up between the cholesterol LDL and the difference between the turbidimetric indices (heparin Ca -- SDS). In the first case, we were thus measuring by turbidimetry a VLDL + chylomicron index and, in the second case, an LDL index which permits one to obtain simplified typing of the hyperlipoproteinemias. A nomogram linking the two indices of hyperlipoproteinemia type was drawn up experimentally. This orientation analysis may be completed by electrophoresis on polyacrylamide gel used in concentration gradient and pH. In the system proposed, the lipoproteins were previously stained with tetrazolium nitroblue and clearly shown up. The chylomicrons in particular, become separated from the VLDL, the sinking pre-beta-lipoprotein or Lp (a) was identifiable and the type III hyperlipemia was easily diagnosed.

[Automation of fluorometric enzymatic determination of free and total cholesterol. Application to the determination of the esterification rate]. / Automatisation en fluorimétrie du dosage enzymatique du cholestérol libre et total. Application à la détermination du rapport d'estérification

A fluorimetric, authomatical method for determination of free and total cholesterol in serum is described. Cholesterol esters are splitted into free cholesterol and fatty acids by cholesterol esterase. In the presence of oxygen free cholesterol will be transformed by cholesterol oxydase in delta 4 cholestenone with formation of hydrogen peroxyde. Hydrogen peroxyde oxidizes in the presence of catalase inethanol to formaldehyde which gives with ammonium ions and acetylacetone 3-5 diacetyl 1-4 dihydrolutidine measured by fluorimetry. Withour cholesterol esterase, the reaction allows a measurement of free cholesterol in plasma. So the ratio of ester to total cholesterol is determined by the two steps. Accuracy and precision are very good. Results are well correlated with those obtained with reference methods.

[Insulin and the metabolism of lipoproteins]. / Insuline et métabolisme des lipoprotéines.

In normal individuals, insulin regulates lipoprotein metabolism. It increases hepatic triglycerides (TG) secretion and makes VLDL and chylomicrons post prandial removal easy by stimulating adipose tissue lipoprotein lipase (LPL). Insulin activity and cholesterol rich lipoprotein is more complicated: by its action on VLDL and chylomicrons turn-over, it influences LDL and HDL formation. It regulates cellular cholesterol pool at different levels: stimulation of LDL receptor, but also of HMG CoA reductase. Controlling LCAT, in participates in cholesterol removal by HDL. In insulin dependent diabetes, lack of adipose tissue LPL stimulation augments triglycerid-rich lipoproteins, by slowing their catabolism, resulting in a weak increase of LDL and a lowering of HDL. In non insulin dependent diabetes with hyperinsulinism, VLDL are elevated because of insulin stimulation of triglycerid hepatic production. LDL are increasing. HDL status remains discussed: HDL cholesterol is low but HDL triglycerid is high, there is no known disturbance of apo A level. In the two types of diabetes, although mechanism is different, perturbation of lipoprotein metabolism may account for the atherogenicity of this disorders.

[Value of the analysis of lipoproteins after myocardial infarction]. / Intérêt de l'analyse des lipoprotéines après infarctus du myocarde.

Lipid and apoprotein constituents of plasma lipoproteins were determined in survivors of myocardial infarction in relation to a control population. Compared to controls, the patients had significantly higher concentrations of total triglycerides, VLDL + LDL - cholesterol and apo-B, but lower concentrations of HLD-cholesterol, HDL2-cholesterol, HDL3-cholesterol, apo A-I and A-II. Survivors with normal lipaemia also had perturbations in HDL and subfractions (HDL2 and HDL3). In addition, the patients exhibited a significant decrease in HDL-cholesterol to VLDL + LDL-cholesterol ratio and in apo A-I to apo-B ratio. These results demonstrate the importance of determining all lipoproteins in future biological studies to evaluate more precisely the relationship between these compounds and atherosclerosis.