[Activities of pulmonary phospholipases of fetal rats. Variations during development]. / Activités phospholipasiques pulmonaires du foetus de rat. Variations au cours du développement

Turnover of adult rat lung phospholipids implies intervention of phospholipases. This work clearly demonstrates: There is in fetal or adult rat lung an inactive form of phospholipase that is convertible to an active form by the action of lysed platelets. An increase of both active and inactive forms of the fetal enzyme with gestational age. The fact that an important part of these activities, at the time of birth, are in the inactive form implies a control mechanism affecting levels of each form of lung phospholipases. These data are discussed in relation to the possible role of the lung phospholipases in Respiratory Distress Syndrome.

Long-term efficacy and safety of a new olive oil-based intravenous fat emulsion in pediatric patients: a double-blind randomized study.

BACKGROUND: A new intravenous lipid emulsion (ILE) prepared from a mixture of soybean and olive oils contains only long-chain triacylglycerols, with a low proportion (20%) of polyunsaturated fatty acids and 60% monounsaturated fatty acids. OBJECTIVE: The goal of this randomized, double-blind clinical trial was to assess in children the efficacy and safety of this new ILE compared with a control group receiving a soybean-oil emulsion. DESIGN: Eighteen children received for 2 mo 24% of nonprotein energy (1.80 g kg (-)(1) d(-)(1)) either as the new ILE or a soybean oil-based emulsion. Assessments were performed on days -30, 0, 30, and 60 and the changes (day 60 - day 0) assessed by analysis of variance. RESULTS: There were no significant differences in triacylglycerol, apolipoproteins A-I and B, or HDL cholesterol between the 2 groups, whereas total and LDL cholesterol were higher in the soybean oil group on day 60. The pattern of 20:4n-6 in erythrocyte membranes did not change significantly, nor did the ratio of 20:3n-9 to 20:4n-6. On day 60, 18:1n-9 was significantly higher in the olive oil group, the ratio of Sigma(n)-6 > C(18) + 18:3n-6 to 18:2n-6 was 2.20 +/- 0.09 in the olive oil group and 1.33 +/- 0.16 in the soybean-oil group, and Sigma(n)-3 > C(18) was 3.83 +/- 0.30 in the olive oil group and 4. 03 +/- 0.33 in the soybean-oil group. The peroxidation index was lower after the olive oil treatment. CONCLUSIONS: The olive oil-based emulsion was well tolerated, maintained a normal EFA status, and may be more suitable for prevention of lipid peroxidation than the soybean-oil-based emulsion.

Alterations of lecithin-cholesterol acyltransferase activity during Plasmodium chabaudi rodent malaria.

In non fatal and synchronous P. chabaudi rodent malaria, we observed at the stage of parasitaemia peak, an alteration (50 % decrease) in LCAT activity. This decrease could be related partly to hepatic dysfunction, and mainly to circulating inhibitors released into blood from parasitized red blood cells at each end of a schizogonic cycle. This decrease in LCAT activity, at this step of the infection, accounts for part of the dyslipoproteinemia previously observed (i.e., increase in cholesterol and phospholipids into VLDL-LDL and decrease in the EC series and delayed conversion of Tg-rich lipoproteins into LDL-HDL. At a prepatent step of infection and after the parasitaemia peak, the alterations observed in LCAT activity, (respectively, increase and then decrease), would be related to similar changes in levels of cholesterol of HDL associated to complex changes in triacylglyceride transport and metabolism.

Phospholipase and prophospholipase activities in bronchoalveolar lavage fluid in severe acute pulmonary disease with or without ARDS.

Bronchoalveolar lavages were performed in 21 patients undergoing mechanical ventilation: Group I: coma due to sedative overdose (11 cases), without pulmonary impairment, serving as control group; Group II: severe acute pulmonary disease without ARDS (5 cases); Group III: patients with ARDS (5 cases). In the recovered fluid we measured: total proteins (P) and phospholipids (PL), phospholipasic (PLase) and prophospholipasic (PPLase) activities. In ARDS group, considerable increase of P, (p less than 0.001), and a doubling of PL (p less than 0.02) was found. Total PLase activity was present in all three groups, with a higher mean level in Group III (p less than 0.01). PPLase activities were low or undetectable in four patients of this group. PLase/PL ratio was increased in acute respiratory insufficiency, with or without ARDS, suggesting an increase of surfactant catabolism. The decrease of this ratio when pulmonary function improved, or its increase after deterioration suggest that it is related to changes of surfactant.

[Determination of lecithin-cholesterol acyltransferase. Studies on the precipitation of beta-lipoproteins by dextran sulphate (author's transl)]. / Dosage de la lécithine-cholestérol acyltransferase. Intérêt de la précipitation des beta-lipoprotéines par le sulfate de dextrane.

Uncertainties in assays of lecithin-cholesterol acyltransferase (LCAT) are generally related to the degree of isotopic equilibrium obtained by rapid exchange of unesterified cholesterol between the different lipoproteins. A new method is presented based on the precipitation of serum beta-lipoprotein with sulfated polysaccharides prior to the LCAT determination. In the absence of Beta-lipoproteins, more than 7 per cent of serum free cholesterol is esterified in the first hour and the reaction rate is linear for about 2 h. LCAT activities with normal serum expressed as cholesterol esterified per microliter mol/1/h are lower than the values reported by others. The reason for this discrepancy is that free cholesterol specific activity in total serum does not reflect the true specific activity of LCAT cholesterol substrate.

[An immunoelectrophoretic study of plasma lipoproteins in a case of familial deficiency of lecithin-cholesterol acyltransferase (author's transl)]. / Etude immunoélectrophorétique des lipoprotéines plasmatiques dans un cas de deficience familiale en lécithine-cholésterol acyltransferase

The lipid composition and apopeptide patterns of plasma LDL and VLDL have been studied in a patient with LCAT deficiency, using two-dimensional immunoelectrophoresis. After absorption of a fat meal an elevation of VLDL apopeptides C was observed. Apo-LDL also showed an abnormal relative increase of apo-C. After heparin-induced lipolysis, a shift of apo-C from chylomicra and VLDL to LDL was noticed by the striking increase of apo-C in this last lipoprotein class. In view of the present and previously published results the possible mechanisms involved in lipoprotein catabolism in LCAT deficiency are discussed.

Liver function and plasma antioxidant status in intensive care unit patients requiring total parenteral nutrition: comparison of 2 fat emulsions.

BACKGROUND: Efficacy and safety of an alpha-tocopherol-enriched emulsion incorporating soybean, coconut, olive, and fish oils (SMOF) are compared in terms of biologic parameters to those of soybean oil-based emulsion (LIPOVEN). METHODS: Twenty stressed patients were randomly assigned in a double-blind study to receive at least a 5-day course of total parenteral nutrition. Plasma activities of liver enzymes, C-reactive protein, antioxidant capacity, alpha-tocopherol, retinol, and low density lipoprotein (LDL)-alpha-tocopherol levels were determined. LDL-lipid oxidation is measured after incubation of the LDL in the presence of a prooxidant. RESULTS: The plasma activities of liver enzymes and the phospholipids/apo A1 ratio were increased in both groups. However, in the SMOF group the increases were lower than in the LIPOVEN group and non-significant for the CRP plasma level and the alanineamino-transferase activity. Before parenteral nutrition, the plasma antioxidant status was markedly reduced in both groups. After parenteral nutrition discontinuation, the antioxidant capacity and the amount of LDL-derived oxidation by-products formed were comparable in both groups. There was a significant improvement in plasma lipophilic antioxidant vitamins and LDL-alpha-tocopherol levels only in the SMOF group. CONCLUSIONS: The lower increase of plasma liver enzymes and phospholipids/apo A1 ratio in the SMOF group suggest a better liver function than in the LIPOVEN group. This beneficial effect results in a higher liver mobilization and plasma levels of lipophilic antioxidants. They could, together with higher delivery of omega-3 fatty acids to peripheral tissues, contribute positively to survival rate of stressed patients.

Lead effect on the oxidation resistance of erythrocyte membrane in rat triton-induced hyperlipidemia.

The anemia observed in severe chronic lead poisoning is in part attributable to alterations in the erythrocyte physicochemical properties. Since they are partly related to the membrane lipid composition, the aim of the present study was to determine the effects of a triton-induced hyperlipidemia on the resistance to oxidation of erythrocyte membranes in lead-treated Wistar rats. Our results showed that triton administration to lead-treated rats induced an increase in erythrocyte choline phospholipid levels together with a significant decrease in the erythrocyte membrane lipid resistance to oxidation. These results led us to suggest that anemia in lead poisoning is linked to interactions between lead present in the membrane and plasma phospholipids. Their increase in rat hyperlipidemia induced by triton resulted in a decrease in the membrane resistance to oxidation and finally in an erythrocyte fragility leading to their destruction.

A rapid method for lecithin:cholesterol acyltransferase estimation in human serum.

All the described procedures for lecithin:cholesterol acyltransferase (LCAT) determination in the plasma have raised criticisms: Lack of sensitivity for methods using colorimetric determination of unesterified cholesterol or phosphatidyl-choline in plasma before and after incubation at 37 degrees C. Incomplete isotopic equilibrium of the free cholesterol substrate between the different lipoproteins in radioassay procedures. Gas-liquid chromatography methods cannot be used when LCAT activity is low. A new method, easier, more sensitive and accurate has been developed in our laboratory:plasma samples are delipoproteinized by coprecipitation with Intralipid, dextran sulphate, and calcium chloride. Cholesterol esterification is assayed by a short incubation (30 min) of 100 microliter delipoproteinized plasma and a 30 microliter of 3H-cholesterol-labelled substrate. About 15% of cholesterol is esterified in these conditions in 30 min (35 +/- 7 micromole/h/l). The LCAT reaction is linear for about one hour.

[Practical value of the selective precipitation of LDL, LDL-phospholipids and the molar ratio of cholesterol to LDL-phospholipids in lecithin-cholesterol-acyltransferase deficiency]. / Intérêt pratique de la précipitation sélective des LDL, LDL-phospholipides et rapport molaire cholestérol sur phospholipides des LDL (LDL-RMCP) dans les déficiences en lécithine-cholestérol-acyl-transférase.

There is a high morbidity from hepato-biliary disease in France. These diseases are often accompanied by a reduction in serum lecithin-cholesterol-acyl-transferase activity, which is difficult and costly to diagnose in the laboratory. Thanks to a simple and inexpensive method of selective precipitation of light lipoproteins, we have been able to establish the practical value of the determination of the LDL-phospholipids and the molar cholesterol ratio on the phospholipids in the LDL (MCPR) in familial or secondary deficiencies of Lecithin-Cholesterol-Acyl-Transferase. These conditions are characterized by a high proportion of serum phospholipids transported by the LDL (more than 60%) and by the marked reduction in the cholesterol ratio of the phospholipids in the LDL. The authors propose a classification for the commonest causes of lecithin-cholesterol-acyl-transferase deficiency.

[Value of LDL-cholesterol determination in hyperlipoproteinemias]. / Intérêt de la détermination du LDL-cholestérol dans les hyperlipoprotéinémies.

Serum LDL-cholesterol concentrations were measured after precipitation in various forms of dyslipidaemia. LDL-cholesterol values were increased in hypercholesterolaemia and decreased in hypertriglyceridaemia. The LDL-cholesterol/total cholesterol ratio decreased with the presence of triglycerides. These data have prompted the authors to propose a classification of dyslipidaemia into hyper-and hypoLDLaemia. Such a classification would be helpful in the prevention, diagnosis and therapeutic surveillance of these diseases.

[In vitro peroxidation of plasma and erythrocyte lipids during WR-1339 induced hyperlipidemia in Wistar rats]. / Peroxydation in vitro des lipides plasmatiques et érythrocytaires au cours de l'hyperlipémie post-triton WR-1339 chez le rat Wistar.

The inhibition of lipoprotein catabolism after triton WR-1339 intravenous administration is associated with an impressive modification in the balance between plasma peroxidable substrates and antioxidants. Treated rat plasma and membrane lipids become peroxiaable when they are incubated with phenylhydrazine in standardized conditions and the production of thiobarbituric acid-reactive substances (lipoperoxidation markers) significantly increases. An accumulation of native lipoproteins which present a decreased alpha-tocopherol on triglycerid ratio and a modification in the plasmatic balance between alpha-tocopherol and ascorbate could explain these observations.