J Lecerf

Institut National des Sciences Appliquées de Lyon, Lyons, Rhône-Alpes, France

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Publications (16)54.85 Total impact

  • World review of nutrition and dietetics 02/2001; 88:173-7.
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    ABSTRACT: The metabolic fate of docosahexaenoic acid (DHA) was evaluated from its intake as a nutrient in triglycerides and phosphatidylcholines to its uptake by target tissues, especially the brain. Several approaches were used including the kinetics and tissue distribution of ingested 13C-labeled DHA, the incorporation of radiolabeled DHA injected as its nonesterified form compared to the fatty acid esterified in lysophosphatidylcholine (lysoPC), and the capacity of the two latter forms to cross a reconstituted blood-brain barrier (BBB) consisting of cocultures of brain-capillary endothelial cells and astrocytes. The results obtained allow us to raise the hypothesis that lysoPC may represent a preferred physiological carrier of DHA to the brain.
    Journal of Molecular Neuroscience 01/2001; 16(2-3):201-4; discussion 215-21. · 2.89 Impact Factor
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    ABSTRACT: The passage of either unesterified docosahexaenoic acid (DHA) or lysophosphatidylcholine-containing DHA (lysoPC-DHA) through an in vitro model of the blood-brain barrier was investigated. The model was constituted by a brain capillary endothelial cell monolayer set over the medium of an astrocyte culture. Cells were incubated for 4 h with a medium devoid of serum, then the endothelial cell medium was replaced by the same medium containing labeled DHA or lysoPC-DHA and incubations were performed for 2 h. DHA uptake by cells and its transfer to the lower medium (astrocyte medium when they were present) were measured. When the lower medium from preincubation and astrocytes were maintained during incubation, the passage of lysoPC-DHA was higher than that of unesterified DHA. The passage of both forms decreased when astrocytes were removed. The preference for lysoPC-DHA was not seen when the lower medium from preincubation was replaced by fresh medium, and was reversed when albumin was added to the lower medium. A preferential lysoPC-DHA passage also occurred after 2 h with brain endothelial cells cultured without astrocytes but not with aortic endothelial cells cultured and incubated under the same conditions. Altogether, these results suggest that the blood-brain barrier cells released components favoring the DHA transfer and exhibit a preference for lysoPC-DHA.
    Journal of Neurochemistry 02/1999; 72(1):338-45. · 3.97 Impact Factor
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    ABSTRACT: To determine the respective roles of endothelial cells from brain capillaries and astrocytes in the conversion of circulating 18:2n-6 and 18:3n-3 into 20:4n-6 and 22:6n-3, respectively, a coculture of the two cell types mimicking the in vivo blood-brain barrier was used. During the culture period, endothelial cells cultured on an insert were set above the medium of a Petri dish containing or not a stabilized culture of astrocytes. Five days after confluence, labeled 18:2n-6 and 18:3n-3 (10 microM each) were added to the endothelial cells and incubated for 48 h. Analogous experiments were also performed by using each cell type cultured alone in the culture device. The distribution of radioactivity in lipids and fatty acids was studied in all the compartments of the culture device. Endothelial cells cultured alone weakly converted the precursor fatty acids into 20:4n-6 and 22:6n-3. When endothelial cells were cocultured with astrocytes, their content of polyunsaturated fatty acids increased dramatically. This effect was associated with the uptake of polyunsaturated fatty acids from the lower medium (astrocyte medium). These fatty acids were released by astrocytes after they were synthesized from the precursor fatty acids that passed through the endothelial cell monolayer into the lower medium. Polyunsaturated fatty acids were released by astrocytes as unesterified fatty acids and as phospholipids (mainly phosphatidylcholine and lysophosphatidylcholine) even when the medium was devoid of serum. These results suggest that astrocytes could play a major role in the delivery of essential polyunsaturated fatty acids to the barrier itself and to the brain.
    The Journal of Lipid Research 10/1998; 39(9):1816-24. · 4.39 Impact Factor
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    ABSTRACT: Docosahexaenoic acid (22:6) decreases blood platelet function and is highly concentrated in the brain where its depletion leads to functional impairments. Because the platelets and blood brain barrier capillary endothelium cannot hydrolyze the complex lipids for fatty acid (FA) uptake, nonesterified FA (NEFA) bound to albumin are assumed to be the delivery route of FA to these cells. The supply of 13C-labeled 22:6 to blood cells by plasma albumin was studied in humans after a single ingestion of this FA esterified in a triglyceride (TG). The 22:6 13C/12C ratio, measured by gas chromatography combustion-isotope ratio mass spectrometry was measured in lipid classes from albumin, platelets, leukocytes, and erythrocytes (taken as a tentative index of the brain uptake). Nonesterified [13C]22:6 bound to albumin was rapidly produced after ingestion, as a result of the hydrolysis of very low density lipoprotein (VLDL) plus chylomicron TG. We found that albumin carried another source of 22:6, lyso-phosphatidylcholines (lyso-PC), in which [13C]22:6 accumulated while the nonesterified [13C]22:6 reached its minimal plasma concentrations. Computation of the relative contribution of NEFA and lyso-PC for the [13C]22:6 delivery to platelets and erythrocytes showed that the [13C]22:6 supply to platelets occurred uniquely through NEFA, whereas this pool was weakly involved in the delivery to erythrocytes. In contrast, lyso-PC was uniquely concerned with the 22:6 delivery to erythrocytes and represented the major part of this supply. We conclude that plasma albumin carries 22:6 in two lipid forms that are involved differently in the delivery of this FA to target cells.
    The Journal of Lipid Research 09/1997; 38(8):1571-82. · 4.39 Impact Factor
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    ABSTRACT: The appearance of 13C in rat lipoprotein, blood cells, and brain lipids was followed as a function of time after the ingestion of triglycerides (TG) containing [13C]22:6n-3. The time course of 13C abundance in 22:6n-3 of various lipid pools, measured by gas chromatography combustion-isotope mass spectrometry, established precursor-product relationships within lipids. The [13C]22:6n-3 was rapidly incorporated into very low density lipoprotein-chylomicron-TG and unesterified fatty acids bound to albumin, with a concomitant maximal appearance at 3 h and further decline. Lysophosphatidylcholines (lysoPC) bound to albumin were also enriched in [13C]22:6n-3, and their labeling appeared to be mainly due to hepatic secretion at the earliest time points. From 12 h postingestion, the synthesis of [13C]22:6n-3-lysoPC was twice as high as that of unesterified [13C]22:6n-3, making lysoPC a potential source of 22:6n-3 supply for tissues. The labeling of platelets, red blood cells, and brain phospholipids presented different kinetics, presumably involving the two lipid forms of [13C]22:6n-3 bound to albumin, to different extents. We conclude that [13C]22:6n-3 esterified in TG is rapidly redistributed within blood lipoproteins and the albumin fraction and that its incorporation in lipid species bound to albumin influences its uptake by target tissues.
    The American journal of physiology 05/1996; 270(4 Pt 2):R846-54. · 3.28 Impact Factor
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    ABSTRACT: The uptake and metabolism of [3H]docosahexaenoic acid (DHA) esterified at the sn-2 position of lysophosphatidylcholine (lysoPC DHA) and in the unesterified form, both bound to albumin, was studied in 20-day-old rats. LysoPC DHA was preferentially recovered in the brain (4-5% of the injected radioactivity) over the unesterified form of DHA (0.3-0.4%). Conversely, the lysoPC form was taken up less than or at the same extent as the unesterified form by the liver, heart, and kidney. In the brain, DHA was mainly recovered in phosphatidylethanolamine whether the esterified or the unesterified form was used, although DHA from lysoPC was esterified at the same extent in phosphatidylcholine and phosphatidylethanolamine after 2.5 min. The uptake of labeled palmitic, oleic, linoleic, and arachidonic acids, esterified or not in lysophosphatidylcholine, was also studied in brain, liver, heart, and kidney. Only the brain preferentially incorporated unsaturated (but not saturated) lysoPC, with the uptake increasing with the degree of unsaturation of the fatty acid moiety. These results strongly suggest that the young rat brain specifically utilizes albumin-lysoPC-containing polyunsaturated fatty acids.
    The American journal of physiology 12/1994; 267(5 Pt 2):R1273-9. · 3.28 Impact Factor
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    ABSTRACT: A gas-chromatography combustion isotope ratio mass spectrometry (GCC-IRMS) method using carbon 13 (13C)-stable isotope to trace n-3 polyunsaturated fatty acids (PUFA) turnover in vivo is presented. Natural 13C abundance of commercial n-3 PUFA was measured from 100 to 300 ng of fatty acids and was -27.58, -27.83, and -28.16 for 22:6n-3, 22:5n-3, and 20:5n-3, expressed as delta 13C /1000 versus Pee Dee Belemnite (PDB), respectively. Precision of delta 13C /1000 values was comparable for the three PUFA and gave relative standard deviations of 0.95-0.97%. Isotope enrichment of 0.0010 at.% could be detected. Triglycerides enriched in [13C]22:6n-3 ([13C]22:6-TG) were synthesized by growing a microalgae on [1-13C]glucose. [13C]22:6n-3 represented 36 wt.% of total triglyceride fatty acids and had an isotope enrichment of 2.0420 at.%, which was the double of natural abundance. The isotope enrichment of 22:6n-3 in lipids from rat lipoproteins and red cells could be followed as a function of time after ingestion of 3 mg [13C]22:6-TG and showed specific patterns according to the lipid compartments. The retroconversion of [13C]22:6n-3 was also detected in HDL phosphatidylcholine by the appearance of [13C]22:5n-3 and [13C]20:5n-3. On the other hand, 22:6n-3 natural 13C abundance in human lipid classes of lipoproteins and blood cells has been measured using 10 ml plasma, even for the more limiting lipid compartments in terms of 22:6n-3 dose size.(ABSTRACT TRUNCATED AT 250 WORDS)
    Analytical Biochemistry 08/1994; 220(1):192-9. · 2.58 Impact Factor
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    ABSTRACT: Fatty acid composition of lipid classes and NMR spectra of lipoproteins were compared in 6 young (24-35-year-old) and 6 elderly (79-90-year-old) women. Cholesteryl ester, triglyceride and protein content of LDL in elderly women were significantly higher (+52-57% and +20% for lipids and proteins, respectively) than those observed in young women. HDL lipid levels were similar in the two groups. The proportion of linoleic acid (mainly in cholesteryl esters and phospholipids) of each lipoprotein species was always lower in octogenarians when compared with young females (lowering of 13-28% and 27-46% for cholesteryl esters and phospholipids, respectively). Conversely, the proportions of mono-unsaturated fatty acids (mainly oleic acid) increased in all lipid classes, although this was only significant in cholesteryl esters from each lipoprotein species. NMR spectra of lipoproteins showed a restricted mobility of acyl chain terminal CH3 groups in old women which was significant only in VLDL and HDL3. This suggests that the decrease of linoleic acid could affect the lipid mobility in lipoproteins of elderly women.
    Atherosclerosis 02/1993; 98(2):241-9. · 3.71 Impact Factor
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    ABSTRACT: The aim of the present study was to investigate whether unsaturated 2-acyl-lysophosphatidylcholine bound to plasma albumin is a relevant delivery form of unsaturated fatty acids to the developing brain. Twenty-day-old rats were perfused for 30 s with labeled palmitic, oleic, linoleic, and arachidonic acids in either their unesterified form or esterified in 2-acyl-lysophosphatidylcholine labeled on the choline and fatty acid moieties. Both forms were bound to albumin. Incorporation in brain lipid classes was followed within 1 h. The brain uptake of the unesterified fatty acids reached a plateau at 5-15 min and was maximal for arachidonic acid (0.45% of the perfused dose). The brain uptake of palmitoyl-lysophosphatidylcholine was similar to that of palmitic acid, whereas that of other lysophosphatidylcholines increased with the degree of unsaturation (rate and maximal uptake) and was six- to 10-fold higher than that of the corresponding unesterified fatty acid. 2-Acyl-lysophosphatidylcholines were taken up without prior hydrolysis and reacylated into doubly labeled phosphatidylcholine, which was the most labeled lipid class, whereas lipid distribution of the unesterified fatty acid was more diversified. Partial hydrolysis of 2-acyl-lysophosphatidylcholine occurred in the brain tissue, and redistribution of the fatty acyl moiety into other phospholipid classes was also observed and was the highest for arachidonic acid. In this case, the percentage of esterification of this fatty acid in phosphatidylinositol (expressed as a percentage of the total lipid fraction) was relatively lower than that observed when the unesterified form was used.(ABSTRACT TRUNCATED AT 250 WORDS)
    Journal of Neurochemistry 10/1992; 59(3):1110-6. · 3.97 Impact Factor
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    ABSTRACT: The metabolic fate of high density lipoprotein (HDL) sphingomyelin in plasma was studied in rats over a 24-hr period after injection of HDL containing sphingomyelin which was 14C-labeled in the stearic (18:0) or lignoceric acid (24:0) moiety and 3H-labeled in the choline methyl groups. Decay of label in plasma followed three phases. The first two phases were similar for both isotopes and both types of sphingomyelin (t1/2 approximately 10 and 110 min). However, during the third phase (from 10 hr after injection), 3H label disappeared more slowly than 14C label from 18:0 sphingomyelin, whereas the 3H/14C ratio remained relatively constant when 24:0 sphingomyelin was used. Intact, doubly-labeled 18:0 sphingomyelin disappeared from HDL rapidly (t1/2 = 38 min) by tissue uptake and by transfer to very low density lipoprotein (VLDL). VLDL contained up to 12% of the sphingomyelin 1 hr after injection. This is the first demonstration of a transfer in vivo of sphingomyelin from HDL to VLDL. A similarly rapid transfer was also observed in vitro. Some nontritiated, [14C]18:0 or [14C]24:0 sphingomyelin was redistributed more slowly into HDL. Doubly-labeled phosphatidylcholine appeared in VLDL and HDL within 1 hr after injection and reached 1.8 and 2.1% of the injected 14C and 3H in VLDL at 1 hr, and 4.8 and 6.9% in HDL at 3 hr, respectively.
    Lipids 11/1990; 25(10):653-60. · 2.56 Impact Factor
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    ABSTRACT: Utilization of stearic and lignoceric acids supplied by high-density lipoprotein (HDL) sphingomyelin to different tissues was followed for 24 h after rats were injected with HDL containing [[1-14C]stearic (18:0) or [1-14C]lignoceric (24:0) acid [Me-3H]choline]sphingomyelin. Both isotopes reached a maximum in tissue lipids 3-12 h after injection and were recovered mainly in the liver (30%) and small intestine (3%), whereas the other tissues contained approx. 1% or less of the injected dose. All the tissues were able to take up some intact sphingomyelin from HDL and hydrolyze it. In the lung and erythrocytes, the 3H:14C ratio of sphingomyelin remained unchanged throughout the studied period, while an increase in the isotopic ratio was observed in the kidney due to the 3H choline moiety re-used for synthesis of new sphingomyelin. Conversely, the isotopic ratio of sphingomyelin decreased in the liver, indicating a saving of the 14C-labelled fatty acids, especially 24:0. Furthermore, [24:0]ceramide in the liver remained at a high level (6% of the injected dose), whereas [18:0]ceramide decreased to 1%. When the tissues were examined 24 h after injection, the proportion of the 14C linked to sphingomyelin in the total 14C was always higher for both kinds of sphingomyelin than the molar proportion of sphingomyelin in the whole of lipid classes. However, in the majority of the extra-hepatic tissues, more [14C]18:0 than [14C]24:0 was recovered in sphingomyelin, and more 14C radioactivity from 18:0 than from 24:0 was redistributed in the other lipids. The choline moiety from both kinds of sphingomyelin was re-used to synthesize phosphatidylcholine, especially in the liver (up to 20% of the injected dose). All these results show that utilization of sphingomyelin from HDL by tissues normally occurs in vivo and that this phenomenon should be taken into account in the study of the phospholipid turnover of cell membranes. They also show that metabolism of sphingomyelin from HDL in the liver and other tissues is dependent on the sphingomyelin acyl moiety.
    Biochimica et Biophysica Acta 05/1990; 1043(2):134-42. · 4.66 Impact Factor
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    ABSTRACT: Isolated rat brain capillaries were incubated in the presence of high-density lipoprotein (HDL) containing [stearic acid-14C, (methyl-3H)choline]sphingomyelin. This double-labeled sphingomyelin was taken up in a concentration-dependent manner. Cerebral capillary-associated sphingomyelin had a 3H/14C ratio close to that of the incubation medium, a result indicating uptake of sphingomyelin without prior hydrolysis. TLC of lipid extracted from capillaries showed that part of the sphingomyelin (up to 40%) was hydrolyzed in the brain capillaries to ceramide and free fatty acids. The hydrolysis was proportional to the amount of incorporated sphingomyelin and reached a plateau when the HDL sphingomyelin concentration in the medium was 237 nmol/ml. The results of "pulse-chase" experiments showed that the choline moiety of sphingomyelin was recovered in the incubation medium after the chase period and that there was no redistribution of liberated choline in phosphatidyl-choline of capillaries.
    Journal of Neurochemistry 11/1989; 53(4):1031-5. · 3.97 Impact Factor
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    ABSTRACT: Utilization of very long chain saturated fatty acids by brain was studied by injecting 20-day-old and adult rats with high-density lipoprotein containing [stearic or lignoceric acid-14C, (methyl-3H)choline]sphingomyelin. Labeling was followed for 24 h. Very small amounts of 14C were recovered in the brain of all rats, and there was no preferential uptake of lignoceric acid. Approximately 20% of the entrapped 14C was located in the form of unchanged sphingomyelin 24 h after injection. This result shows that the rat brain utilizes very little very long chain fatty acids (greater than or equal to 20 C atoms) from high-density lipoprotein sphingomyelin, even during the myelinating period. The [3H]choline moiety from sphingomyelin was recovered in brain phosphatidylcholine in a higher proportion in comparison with the 14C uptake. The brain 3H increased throughout the studied period in all experiments, but was much higher in the myelinating brain than in the mature brain. From the radioactivity distribution in liver and plasma lipids, it is clear that the choline 3H in the brain originates from either double-labeled phosphatidylcholine of lipoproteins or tritiated lysophosphatidylcholine bound to albumin, both synthesized by the liver.
    Journal of Neurochemistry 06/1989; 52(5):1495-500. · 3.97 Impact Factor
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    ABSTRACT: Rat HDL containing [stearic acid-14C, (methyl-3H)choline]sphingomyelin was prepared by incubating labelled sphingomyelin liposomes with serum. HDL was then separated by ultracentrifugation and purified by gel-filtration chromatography. The maximum transfer was reached when 1.5 microliter sphingomyelin was incubated in the presence of 1 ml of serum at 37 degrees C for 1 h. When transfer was limited to a 5-7% increase in HDL mass, no significant change was observed in the HDL electrophoretic pattern, and rats could therefore be injected with this type of HDL under physiological conditions. Plasma radioactivity decay was followed for 24 h, and the recovery of both isotopes in 11 tissues was studied 24 h after the injection. The decay in plasma of both isotopes followed three exponential phases. During the first two phases, both isotopes disappeared with the same velocity (t1/2 = 12.8 and 98-105 min for the first and second phases, respectively). 10 h after injection, 3H had disappeared more slowly than 14C (t1/2 = 862 and 502 min for 3H and 14C, respectively) and 24 h after injection, only 1.5% of 14C and 2.5% of 3H remained in the plasma. This radioactivity was located mainly in HDL (80-85% for 3H and 14C), with a 3H/14C ratio close to that of injected sphingomyelin, and in VLDL, with the same isotopic ratio as that of liver lipids. Some 3H was associated with non-lipoprotein proteins. 17.5% of 3H and 23.4% of 14C were recovered in the liver, 1.6% of each isotope in erythrocytes, and 1.4% of 3H and 0.6% of 14C in kidney. Less than 1% of each isotope was recovered in each of the other tissues. Phosphatidylcholine was the lipid most labelled, and in several tissues sphingomyelin had a 3H/14C ratio close to that of injected sphingomyelin, showing an uptake without prior hydrolysis.
    Biochimica et Biophysica Acta 05/1988; 959(3):349-60. · 4.66 Impact Factor
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    ABSTRACT: The exchange of docosahexaenoic acid (22:6n-3) within lipid pools in rat and human has been followed as a function of time after the ingestion of triglycerides (TG) containing 22:6n-3 labeled with13C(13C 22:6n-3). The13C abundance in the fatty acid was measured by gas-chromatography-combustion isotope ratio mass spectrometry which allowed the detection of 0.001 atom13C percent12C. The13C 22:6n-3 appearance was rapid in the TG of very low density lipoprotein plus chylomicron fraction, in which the maximal labeling was observed at 3 and 2 h after ingestion in rat and human, respectively. Concomitant with the TG utilization of this fraction by lipoprotein lipase from tissues, unesterified13C 22:6n-3 appeared in the plasma albumin.13C 22:6n-3 bound to albumin was mostly present in unesterified form before 12 h post-ingestion while after that period, lysophosphatidylcholine (lysoPC) bound to albumin carried higher13C 22:6n-3 concentrations. These lyso-PC were mostly from hepatic origin and might represent a potential source of 22:6n-3 redistribution to tissues. The13C 22:6n-3 uptake into rat brain PC and phosphatidylethanolamine was still increasing when the concentration of plasma unesterified13C 22:6n-3 had already dropped to a minimal plateau value and during the period of maximal plasma circulation of13C 22:6n-3-lysoPC bound to albumin. In contrast, the uptake of13C 22:6n-3 into blood platelet PC occurred during the phase of important circulation of13C-22:6n-3 bound to albumin, suggesting thein vivo efficiency of the Lands pathway for this fatty acid. It is concluded that13C 22:6n-3 esterified in TG is rapidly absorbed and redistributed within plasma lipoproteins and that its redistribution within the two lipid species bound to albumin might influence its uptake by platelets and rat brain.
    Lipids 31(1):S109-S115. · 2.56 Impact Factor

Publication Stats

307 Citations
54.85 Total Impact Points

Institutions

  • 1996–2001
    • Institut National des Sciences Appliquées de Lyon
      Lyons, Rhône-Alpes, France
  • 1998
    • Unité Inserm U1077
      Caen, Lower Normandy, France
  • 1994
    • French Institute of Health and Medical Research
      Lutetia Parisorum, Île-de-France, France
  • 1993
    • INSA
      Альтамира, Tamaulipas, Mexico
  • 1992
    • Laboratoire des Sciences du Climat et l'Environnement
      Gif, Île-de-France, France