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M Lagarde

Publications and source records attributed to M Lagarde.

At least 109 records · Page 6Linked to original sources
PubMed1995

Time-course changes in content and fatty acid composition of phosphatidic acid from rat thymocytes during concanavalin A stimulation.

Several studies have shown the potential role of phosphatidic acid (PA) as a second messenger in different cell types. Thus, PA has been shown to mimic physiological agonists leading to various cellular responses, such as neurotransmitter and hormone release, cell proliferation by modulating DNA or RNA synthesis, the expression of several proto-oncogenes and growth factors, and the stimulation of enzyme activities such as phospholipase C (PLC), protein kinases and cyclic AMP (cAMP) phosphodiesterase. Stimulation of [3H]arachidonate-labelled rat thymocytes with the mitogen lectin concanavalin A (con A) resulted in enhanced production of radiolabelled PA after only 5 min of activation. The radiolabelled PA increase corresponded to a real increase in PA mass as determined by GLC quantification of its fatty acid content. In the presence of ethanol (0.5%), formation of phosphatidylethanol was not observed after 5 min of con A activation. Pretreatment of cells with R 59022 (10 microM), a diacylglycerol (DAG) kinase inhibitor, showed an inhibition in the formation of radiolabelled PA and in PA mass. These results suggest that the PLC-DAG kinase may be the pathway for PA synthesis in the first minutes of mitogenic thymocyte activation. A detailed analysis of the fatty acid composition showed that the relative amount of unsaturated fatty acids was increased in PA from stimulated cells concomitantly with a decrease in saturated ones; in particular, arachidonic acid was increased approximately 2-fold only 2 min after con A addition whereas palmitic acid was decreased for the whole period investigated (20 min). These changes favour the hydolysis of phosphoinositides rather than phosphatidylcholines by PLC. As PA remains a minor phospholipid, these changes are unlikely to affect cell membrane fluidity; but PA being now well recognized as a potential second messenger, its increased content as well as its increased unsaturation in the fatty acyl moiety might modulate several signalling pathways or the activity of enzymes such as cyclic nucleotide phosphodiesterase, controlling in this way the cellular level of cAMP, a negative regulator of blastic transformation.

Animals↗
PubMed1995

Interconversions and distinct metabolic fate of eicosapentaenoic, docosapentaenoic and docosahexaenoic acids in bovine aortic endothelial cells.

The anti-aggregatory activity of endothelial cells being affected by eicosapentaenoic (EPA, 20:5(n-3)) and docosahexaenoic (DHA, 22:6(n-3)) acids, the two main polyunsaturated fatty acids of fish oil, these fatty acids, as well as their intermediary, docosapentaenoic acid (DPA, 22:5(n-3)), were investigated with respect to their metabolism. Primary cultured bovine aortic endothelial cells were supplemented for 22 h at 37 degrees C with either n-3 fatty acid, and the fatty acids of cell media, of cell lipid classes, and of choline and ethanolamine glycerophospholipids (PC and PE) were quantified. Endothelial cells converted each of the three fatty acids into the two others. They were found esterified in cell lipids and partly released in cell media, the respective parts varying according to the fatty acid. For instance, half of the DPA formed from EPA and two third of the EPA formed from DPA were released in the media. Moreover, the DHA formed from EPA and DPA was not esterified but released in media. In addition, the esterified counterparts were found in either PC or PE, depending on whether they were added or formed by conversions. It is concluded that EPA, DPA and DHA are actively interconverted each others, and differ substantially in terms of distribution between media and cells, and within phospholipid classes.

Animals↗
PubMed1995

Docosahexaenoic acid is a potent inhibitor of rat uterine stromal cell proliferation.

The effect of different families of fatty acids on the proliferation of rat uterine stromal cells (UIII) was studied. Docosahexaenoic acid (DHA) exerted a strong and dose-dependent inhibitory effect (IC50 approximately 2 microM), whereas arachidonic acid (AA) stimulated UIII cell proliferation at the optimal concentration of 10 microM. Oleic, linoleic and linolenic acids were ineffective from 0.1 to 10 microM. The inhibitory effect of DHA was independent of the eicosanoid biosynthesis and lipid peroxidation, since it was not reversed by the addition of the antioxidant BHT and no significant production of oxidized species from DHA occurred in our culture conditions.

Animals↗
PubMed1995

Distribution and metabolism of arachidonic and docosahexaenoic acids in rat pineal cells. Effect of norepinephrine.

The time-course incorporation of 10 microM [14C]arachidonic (AA) and docosahexaenoic (DHA) acids into glycerolipids was studied in rat pineal cells. The incorporation of both labeled fatty acids into total lipids was approximately equal, but their distribution profiles among the various cell lipids showed marked differences. The esterification of [14C]DHA in the neutral lipids, triacylglycerols (TAG) and cholesterol esters (CE), was 2-fold higher than that of [14C]AA whereas the opposite could be observed in total phospholipids (PL). The order of incorporation into PL was phosphatidylcholine (PC) > phosphatidylinositol (PI) = phosphatidylethanolamine (PE) for [14C]AA and PC = PE for [14C]DHA, the incorporation of both fatty acids being not detected in phosphatidylserine (PS) and that of DHA not in PI. When using 0.5 microM [3H] fatty acids, the respective distribution patterns resembled that of fatty acids at 10 microM, except for a lower proportion in TAG. The stimulation of 3H-labeled cells by 100 microM norepinephrine induced a 170% increase of basal release of [3H]AA into the medium, while [3H]DHA was virtually not released. However, the analysis of cell labeling revealed that both [3H] fatty acid levels were decreased in PL and increased in TAG. These findings suggest different involvement for AA and DHA in the pineal function. The preferential incorporation of DHA in TAG suggests that TAG might play an important role in the pineal enrichment with DHA. The absence of DHA release after NE stimulation, which however cannot be ascertained, may raise the question of the role of DHA in NE transduction.

Animals↗
PubMed1995

Esterification of 12(S)-hydroxy-5,8,10,14-eicosatetraenoic acid into the phospholipids of human peripheral blood mononuclear cells: inhibition of the proliferative response.

12-hydroxy-eicosatetraenoic acid (12-HETE), the lipoxygenase metabolite of arachidonic acid produced by activated platelets, has been shown to accumulate in peripheral blood mononuclear cells (PBMC) of elderly people. 12-HETE being antimitogenic for lymphocytes, its accumulation in blood cells might be involved in the well-known decline in immune function which accompanies aging. Because HETEs have been shown to be rapidly metabolized and/or incorporated into cellular lipids in a variety of cell types, we have investigated the uptake, metabolism, and intracellular distribution of exogenous 12-HETE by human PBMC. [3H]-12-HETE was dose and time dependently incorporated by PBMC and also metabolized to more polar products. These polar metabolites were mainly released extracellularly and only marginally esterfied in phospholipids. Although [3H]-12-HETE radiolabel was preferentially associated with phosphatidylcholine, especially after prolonged labeling incubations or following successive short labeling pulses, a substantial amount of radiolabel was also found associated with phosphatidylinositol (20-50% of the labeled phospholipids). The stability of 12-HETE in the phospholipid pool was comparable to that reported for most other cell types, with 50% of the initial radiolabel being still present after 18 hr. Upon exposure to mitogenic activation, 12-HETE-labeled PBMC released unmodified 12-HETE from phosphatidylinositol. In addition, 12-HETE dose dependently inhibited the proliferative response of PBMC to Con A stimulation. These results suggest that 12-HETE esterification in phospholipids might lead to the generation of unusual lipid second messengers with impaired capacity to transduce activation signals, thus decreasing lymphocyte function.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1995

Cross-reactivity of delta 17-6-keto-PGF1 alpha with 6-keto-PGF1 alpha antibodies.

The cross-reactivity of the PGI3 metabolite, delta 17-6-keto-PGF1 alpha, with antibodies against 6-keto-PGF1 alpha for radioimmunoassays (RIA) has been investigated. Delta 17-6-keto-PGF1 alpha was obtained either from commercial sources or after its purification from endothelial cells. In the latter case, primary cultured bovine aortic endothelial cells were incubated for 20 min at 37 degrees C with 10 microM eicosapentaenoic acid (EPA) in the presence of 2 microM 13-hydroperoxy-octadecadienoic acid, and activator of the EPA cyclooxygenation, and the 6-keto-PGF1 alpha and beta 17-6-keto-PGF1 alpha produced were separated by RP-HPLC. Then, cross-reactivities of the commercial and purified beta 17-6-keto-PGF1 alpha with 6-keto-PGF1 alpha antibodies were determined and found not to exceed 10%. In addition, the amounts of prostacyclin-related compounds detected by direct measurements in media of cells loaded with EPA were compared with those obtained after purification of 6-keto-PGF1 alpha. In accordance with the cross-reactivity data, we found that RIA in media mainly measured 6-keto-PGF1 alpha, the beta 17-6-keto-PGF1 alpha formed being undetected at 90%. It is concluded that 6-keto-PGF1 alpha antibodies generally used for RIA of 6-keto-PGF1 alpha are highly specific since they can discriminate a metabolite bearing an additional double band such as the PGI3 metabolite beta 17-6-keto-PGF1 alpha.

6-Ketoprostaglandin F1 alpha↗
PubMed1995

Influence of polyunsaturated fatty acids on lipid metabolism in human blood mononuclear cells and early biochemical events associated with lymphocyte activation.

n-3 and n-6 polyunsaturated fatty acids are involved in the regulation of the immune response. Although different hypotheses related to modifications of arachidonic acid metabolism or alterations at the level of the cell membrane have been put forward to explain their suppressive effect on the lymphocyte growth, their mechanism of action remains largely unknown. Cyclic nucleotide phosphodiesterase (PDE) has been shown to be an important target involved in the control of lymphocyte proliferation. The present study aimed to determine whether in vitro addition of a physiological concentration (5 microM) of n-6 (20:3n-6) or n-3 (18:4n-3, 20:5n-3, 22:6n-3) fatty acids to human peripheral blood mononuclear cells (PBMC) was able to alter the PDE activity of these cells, and especially the PDE increase in response to Con A stimulation. Pretreatment of human PBMC for a short period of time (90 min) with 5 microM of either 20:3n-6, 20:5n-3 or 22:6n-3 was sufficient to induce a significant enrichment of cellular phospholipids in the corresponding fatty acid, whereas 18:4n-3 was poorly incorporated. Either fatty acid significantly increased both cAMP- and cGMP-PDE activities in the cytosolic compartment, the particulate PDE activities being less sensitive to their stimulatory effect. In contrast, they significantly lowered the PDE increase to Con A stimulation. Except 20:5 n-3, the three other fatty acids did not alter significantly the basal or Con A-induced oxygenated metabolism of arachidonic acid (AA), appreciated by the measurement of radioactive eicosanoids formed in [3H]AA-labelled cells. Furthermore, only 20:5n-3 significantly inhibited the lymphoproliferative response to Con A, whereas 16:0, 18:0, 18:1n-9, 20:3n-6 and 20:4n-6 were inactive. The inhibitory effect was not prevented by antioxidant vitamins C and E. The present results suggest that the lymphocyte growth suppressive effect of 20:5n-3 20:5n-3 is very likely to be independent on both the cAMP system and eicosanoid synthesis, and does not seem to involve their conversion to peroxidised products.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1995

Decrease of brain phospholipid synthesis in free-moving n-3 fatty acid deficient rats.

The autoradiographic method with [14C]-docosahexaenoic acid ([14C]22:6 n-3) was used to determine whether a diet deficient in n-3 fatty acids, inducing a decrease in 22:6 n-3 circulating level, was associated with changes in local rates of phospholipid synthesis in the rat brain. As compared with rats fed a normal diet (peanut plus rapeseed oil), a n-3 fatty acid deficiency [peanut oil group (P group)] induced a generalized decrease (-35 to -76%) of 22:6 n-3 incorporation rates into phospholipids in all the regions examined. This effect was confirmed by using [3H]22:6 n-3 infusion by biochemical analysis and quantifications corrected for the contribution of docosahexaenoate derived from lipid store recycling to the unesterified pool, taken as the precursor pool for phospholipid synthesis in the whole brain. In normal or n-3 fatty acid-deficient rats, the values of the brain-to-plasma 22:6 n-3 specific activity ratio (psi) were similar (0.03), indicating that a considerable endogenous source of 22:6 n-3 (97%), likely derived from phospholipid degradation, dilutes the specific activity of the tracer coming from plasma. Using the specific activity of 22:6 n-3 in plasma instead of brain would thus lead to a gross underestimation of the rate of phospholipid synthesis. The results also demonstrate that the pattern of 14C or 3H distribution in brain lipids was not modified by the n-3 fatty acid-deficient diet. The major lipids labeled were phospholipids, particularly phosphatidylethanolamine. Nevertheless, the unesterified 22:6 n-3 concentrations in plasma and brain were significantly reduced (eight-and threefold, respectively) in the P group. In addition, the proportion of 22:6 n-3 in the brain total lipid fraction, total phospholipids, and phosphatidylcholine, -ethanolamine, and -serine was significantly decreased in n-3 fatty acid-deficient rats. This was partially compensated for by an increase in the 22:5 n-6 level. These results are discussed in relation to the limitation of 22:6 n-3 use to quantify, by the quantitative autoradiographic method, changes in local rates of phospholipid synthesis in rat brain.

Animals↗
PubMed1995

Developmental differences in distribution of cyclic nucleotide phosphodiesterase isoforms in cardiomyocytes and the ventricular tissue from newborn and adult rats.

We characterized cyclic nucleotide phosphodiesterase (PDE) activities in neonatal rat cardiomyocytes and in whole ventricle from newborn and adult rats, to determine whether cyclic nucleotide hydrolytic activities might be influenced by the developmental stage of the animal or by cell isolation and culture procedures. Using anion-exchange high-performance liquid chromatography (HPLC), we obtained four soluble PDE activities from adult rat ventricle. Peak 1, a cyclic GMP-specific PDE was stimulated by Ca2+/calmodulin; peak 2 hydrolyzed cyclic AMP and cyclic GMP, the addition of cyclic GMP stimulating the hydrolysis of cyclic AMP. Peaks 3 and 4 selectively hydrolyzed cyclic AMP, peak 3 being very sensitive to inhibition by rolipram and peak 4 consisting of two different enzyme activities, one inhibited by cyclic GMP (peak 4b) and the other inhibited by rolipram (peak 4a). In cardiomyocytes and whole ventricle from newborn rats, the response of the two cyclic GMP-sensitive PDE isoforms (cyclic GMP-stimulated and cyclic GMP-inhibited PDE) to the effector cyclic GMP was markedly reduced as compared with that of the corresponding isoforms (peaks 2 and 4b) present in the heart ventricle of adult rats. The other peaks were analogous to peaks 1, 3, and 4a of the whole ventricle. The profile of PDE activities in nonmyocardial cells did not differ from that of myocytes. Therefore, the lack of cyclic GMP effects was not due to culture conditions. Differences in PDE activities observed between cardiomyocytes from newborn rats and ventricle from adult rats might be age dependent.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1995

Leukotriene B4 production by blood neutrophils in allergic rhinitis--effects of cetirizine.

BACKGROUND: Mucosal inflammatory processes in late phase of allergic diseases involve cytokine production, cell adhesion molecule overexpression and release of inflammatory mediators with chemotactic activity, such as leukotriene B4 (LTB4). We had previously observed increased production of LTB4 by neutrophils in patients with allergic rhinitis and discussed the role of granulocyte macrophage-colony stimulating factor (GM-CSF) priming. Some antihistaminic compounds were shown to diminish the production of leukotrienes by neutrophils. OBJECTIVES: In a first step, we evaluated in ex vivo and in vitro studies, the effects of cetirizine on LTB4 production by blood neutrophils from allergic and healthy subjects. In a second step, we studied the in vitro effect of cetirizine on LTB4 production by neutrophils from healthy subjects during GM-CSF priming of these cells. METHODS: Neutrophils from both populations were purified from venous blood and LTB4 production was measured using high performance liquid cromatography (HPLC) method. RESULTS: In ex vivo studies, cetirizine treatment induced a decreased LTB4 production by neutrophils in allergic rhinitis. This effect of decreased LTB4 production was reproduced in vitro with 10(-8)-10(-6)M cetirizine. Nevertheless, this anti-H1 compound had no effect on neutrophil priming with GM-CSF. CONCLUSION: As LTB4 is an important chemotactic factor, Cetirizine could act on inflammatory cell recruitment by inhibiting LTB4 production by neutrophils.

Adult↗
PubMed1995

[Marfan's syndrome and pregnancy. A case report and review of the literature].

Marfan's syndrome is a collagen tissue disease, identified at the end of the nineteenth century. The gene for this autosomal dominant disease lies on chromosome 15 and leads to a biochemical disorder yet to be described. We report a case of Marfan's disease in a gravid patient and discuss the complications which may occur. The main risk involves the cardiovascular manifestations of the disease with possible dissection or rupture of the aorta. Preventive surgery, with extra-corporal circulation is required when the diameter of the aorta is greater than 6 cm. Spontaneous abortions and risk of premature birth have also been reported. Delivery itself is not a major risk but should be planned in a setting allowing immediate transfer to a cardiac surgery unit. Pregnancy should be discouraged in patients with Marfan's syndrome if the aortic diameter is greater than 4 cm. When pregnancy occurs, echocardiographic examinations of the mother should be performed monthly for the first 6 months, then bimonthly. Prenatal diagnosis is of little interest, except to detect foetuses at risk at delivery.

Adult↗
PubMed1995

Effect of specific phospholipid molecular species incorporated in human platelet membranes on thromboxane A2/prostaglandin H2 receptors.

The incorporation of albumin-bound docosahexaenoic acid (22:6n-3), but not linoleic acid (18:2n-6), into cellular phospholipids inhibits platelet aggregation induced by the thromboxane analogue U46619. [3H]U46619 specific binding to thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptors, as well as specific binding of the antagonist [3H]SQ29548 to these sites were also decreased in these modified cells (P. G., Swann et al. 1990. J. Biol. Chem. 265: 21692-21697). More than 80% of the 22:6n-3 incorporated in these cells was esterified in the various endogenous phospholipid classes and the remaining was found in neutral lipids and in the unesterified fatty acid pool. In this study, we determined whether the effects observed could be attributed to the esterification of 22:6n-3 in phospholipids and whether the 22:6n-3 biological activity might depend on its esterification in specific phospholipid classes. Therefore, pure phosphatidylcholine (PC) and phosphatidylethanolamine (PE) molecular species were transferred to platelet membranes, using lipid transfer proteins. PC and PE containing palmitate (16:0) and 22:6n-3 or 16:0 and 18:2n-6 at position sn-1 and sn-2, respectively, were incorporated into membranes only at the expense of the corresponding endogenous phospholipid class, by an apparent exchange process. When such modified membranes were tested for specific binding of U46619 and SQ29548, a significant decrease of the receptor site affinity was only observed in membranes highly enriched with 1-palmitoyl-2-docosahexaenoyl-glycerophosphocholine (16:0/22:6-GPC). Fluidity parameters measured by electron spin resonance of 5- and 16-nitroxy-stearic acids were not significantly different in membranes enriched with 16:0/22:6-GPC relative to those enriched with 16:0/18:2n-6-GPC, arguing against a generalized perturbation of the membrane due to 22:6n-3 incorporation. We conclude that molecular species of PC with 22:6n-3 at the sn-2 position can affect TXA2/PGH2 receptors. The selectivity of the inhibitory effect of PC containing 22:6n-3 is discussed.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1995

Fatty acid composition of brain capillary endothelial cells: effect of the coculture with astrocytes.

We have investigated the fatty acid composition of brain capillary endothelial cells cultured alone or in coculture with astrocytes, using an in vitro model in which endothelial cells and astrocytes were grown from one part of a filter to another. We found that the fatty acid composition of the cocultured cerebral endothelial cells was markedly different from that of non-cocultivated endothelial cells. The most striking difference was the increase of arachidonic acid (20:4n-6) at the expense of its precursor, linoleic acid (18:2n-6). Similar modifications were found for the n-3 family of fatty acids with an increase of docosahexaenoic acid (22:6n-3) at the expense of its precursors, but the differences were less than within the n-6 fatty acids. These changes induced by the coculture were observed only in endothelial cell phospholipids, especially the phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine classes, but were not detected in phosphatidylinositols and in other lipid classes. Only the composition of the n-3 series fatty acids was altered in another capillary endothelial cell type (from adrenal cortex) cocultured with astrocytes under the same conditions. The fatty acid changes observed might be biologically relevant as they tended to make the fatty acid composition of the brain capillary endothelial cells more closely resemble that of brain microvessels.

Adrenal Cortex↗
PubMed1995

[Biosynthesis and functions of eicosanoids. Recent data].

Eicosanoids are oxygenated derivatives from 20-carbon polyunsaturated fatty acids. Among these, arachidonic acid is the reference precursor from which most metabolic pathways have been described. These pathways correspond to the biosynthesis of prostanoids with a recent revival interest after the discovery of an inducible form of prostaglandin H synthase, the formation of lipoxygenase products catalyzed by three different enzymes according to the initial carbon position of the oxygenation, and the oxygenation into epoxides and into hydroxy derivatives by the cytochrome P450 family. In addition to these enzyme pathways, the formation of prostaglandin isomers by radical-induced oxygenation and cyclization has been recently described and named isoprostanes. Finally, it is noteworthy to state the interest for two fatty acids of marine origin, namely eicosapentaenoic acid, an arachidonic acid analogue competing with it in different metabolic pathways, and docosahexaenoic acid, precursor of few docosanoids and transcriptional regulator of several activities.

Arachidonate Lipoxygenases↗
PubMed1994

Age-related changes in linoleic acid bioconversion by isolated hepatocytes from spontaneously hypertensive and normotensive rats.

This study points out the hepatocyte interconversion of the linoleic acid family during hypertension. Hepatocyte delta 6 desaturase activity was higher in 1 month-old spontaneously hypertensive rats than in normotensive controls. A similar tendency was observed in 6 month-old SHR. delta 5 desaturase activity was higher only in 1 month-old spontaneously hypertensive rats as compared to controls. Desaturase activities were particularly high at the age of 6 months. The hepatocyte fatty acid composition showed an impairment of n-6 polyunsaturated fatty acid metabolism in spontaneously hypertensive animals. Changes were greater in the young prehypertensive rats than in adults. A storage of n-3 long chain fatty acids is remarkable in adult hypertensive rats, suggesting an alteration in peroxisomal oxidation. Such modifications may be related to the prostaglandin precursors availability to peripheral tissues such as kidney.

Aging↗
PubMed1994

Evidence for brain docosahexaenoate recycling in the free-moving adult rat: implications for measurement of phospholipid synthesis.

The specific activity (SA) of unesterified docosahexaenoic acid (22:6 n-3) in the brain and arterial plasma was measured after constant intravenous infusion of [3H] 22:6 n-3 in the free-moving rat. Within 40-105 min, an apparent steady state of labeled unesterified 22:6 n-3 in plasma and in brain was reached. However, the values of the brain to plasma 22:6 n-3 SA ratios ranged from 0.03 to 0.05, indicating that an isotopic equilibrium between brain and plasma was not attained. This suggests that a considerable endogenous source of unesterified 22:6 n-3 (95-97%) (likely derived from lipid metabolism) dilutes the SA of the tracer coming from plasma. Using the SA of 22:6 in plasma instead of brain would thus lead to a gross underestimation of the rate of phospholipid synthesis.

Animals↗