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Biomedical subjects

J Larrue

Publications and source records attributed to J Larrue.

At least 19 recordsLinked to original sources
PubMed1997

Glucocorticoids stimulate cholesteryl ester formation in human smooth muscle cells.

The aim of the present study was to investigate the effect of synthetic glucocorticoid dexamethasone (Dex) on cholesterol esterification in cultured human smooth muscle cells (SMC). In labeled SMC, Dex stimulated the esterification of [3H]cholesterol in a dose-dependent manner. This effect was specific for glucocorticoid hormones and could be inhibited by cycloheximide (3 ng/mL), actinomycin D (10(-5) mol/L), and the specific glucocorticoid antagonist RU 486 (10(-8) mol/L). When plasma membrane was selectively labeled with trace quantities of [3H]cholesterol (0.25 microCi/mL, 1 hour, 10 degrees C), Dex (10(-8) mol/L) caused a net flux of free [3H]cholesterol into the cells. Moreover, Dex (10(-8) mol/L, 24 hours) stimulated the esterification of sterols, newly synthesized from [14C]mevalonate (10 microCi/mL, 4 hours) and lowered the amount of [14C]sterols susceptible for cholesterol oxidase. The incorporation of [14C]oleic acid into cholesteryl esters was markedly higher in Dex-pretreated SMC than in the control cells (2.1 +/- 0.07 and 1.4 +/- 0.1 pmol/h/microgram protein, respectively, P < .01). At the time, cholesteryl ester hydrolysis in Dex-treated cells was reduced (72 +/- 8 pmol cholesteryl esters/h per milligram versus 130 +/- 10 in the control cells). HDL3-mediated [3H]cholesterol efflux was also inhibited in Dex-treated cells; moreover, HDL3 (40 micrograms/mL, 24 hours) had practically no effect on [3H]cholesteryl ester content in Dex-treated SMC but caused a 50% reduction of [3H]cholesteryl esters in the control cells. Thus, in human SMC glucocorticoids alter the redistribution of cholesterol between the pools of free and esterified cholesterol, paralleled by the change in acyl coenzyme A: cholesteryl acyltransferase and neutral cholesteryl ester hydrolase activities, leading to the impaired HDL3-mediated cholesterol efflux.

Adult↗
PubMed1995

15-Lipoxygenase expression in smooth muscle cells from atherosclerotic rabbit aortas.

To determine the extent and origin of the stimulation of 15-lipoxygenase activity in atherosclerotic aortas, formation of hydroxy-derivatives from arachidonic acid was measured by HPLC-analysis and 15-lipoxygenase mRNA expression was investigated by RNA blot and in situ hybridization in atherosclerotic and normal rabbit aortic tissues. The synthesis of hydroxy-eicosatetraenoic acids (HETE) from exogenously added [14C]arachidonic acid was unchanged in atherosclerotic aortas in comparison with healthy aortas, but pretreatment with indomethacin demonstrated that 15-HETE production resulted essentially (75%) from cyclooxygenase activity in healthy aorta and from lipoxygenase activity in atherosclerotic aorta. The RNA blot and in situ hybridization with radiolabelled oligonucleotide probe demonstrated that 15-lipoxygenase mRNA was strictly localized in intimal thickening of atherosclerotic aortas. The immunostaining using anti-alpha smooth muscle actin, revealed that smooth muscle cell rich areas of the intimal thickening expressed 15-lipoxygenase mRNA. In addition, RNA blot hybridization indicated that cultured smooth muscle cells from atherosclerotic aortas expressed strongly 15-lipoxygenase mRNA. These results demonstrate that augmentation of 15-lipoxygenase activity in atherosclerotic aortas is correlated with 15-lipoxygenase mRNA expression in atherosclerotic plaque, and that intimal smooth muscle cells were involved, in addition to macrophages, in the expression of 15-lipoxygenase.

Animals↗
PubMed1994

Modulation of the transcellular metabolism of 12(S)HETE by 10-11 reductase activity in cultured rat aortic smooth muscle cells.

Cultured rat aortic smooth muscle cells (SMC) metabolize 12(S)hydroxyeicosatetraenoic acid (12(S)HETE) by two different pathways; beta-oxidation leading to 16:3(8-OH), and 10-11 reductase activity producing 20:3(12-OH) which is beta-oxidized to 16:2(8-OH). In this work, we demonstrate that 10-11 reductase activity is modulated in cultured rat aortic SMC as a function of cell state (proliferating vs quiescent) and stimulated by serum. Most of the 20:3(12-OH) is recovered in the incubation medium but a significant part is esterified into phospholipids. By comparison with its parent compound, 12(S)HETE, 20:3 (12-OH) is mainly incorporated into phosphatidyl-choline and phosphatidyl-ethanolamine, suggesting that it may affect cellular functions. Taken together, these findings may be relevant to the effects of 12(S)HETE on vascular SMC functions related to atherosclerotic development.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1994

Involvement of endothelium-derived NO in the basal tone and in the vasodilator responses to muscarinic agonists in the rat isolated mesenteric arterial bed.

To investigate the involvement of nitric oxide (NO) derived from endothelial cells in the control of vascular tone in the rat mesenteric vascular bed, the effects of different procedures known to interfere with the NO-cyclic GMP pathway were evaluated both on the basal tone and on the vasodilatory responses to four muscarinic agonists. To this aim, rat isolated mesenteric vascular beds were perfused at constant pressure. Water infusion significantly increased the resting perfusion pressure whereas L-NOARG, L-NAME and methylene blue were devoid of effect. In noradrenaline-preconstricted vascular bed, the perfusion pressure was significantly increased after water or L-NAME infusion. The vasodilator response induced by subsequent addition of acetylcholine in bolus was not significantly modified by pre-treatment with indomethacin but was significantly reduced by water infusion. Responses to acetylcholine and to three other muscarinic agonists--carbachol, oxotremorine or McNeil A 343--were assessed. Incubation with L-NAME did not modify the initial peak falls of the agonists except for McNeil A 343, whereas it significantly reduced the area under the pressure trace for all the substances. The latter effect was reversed after a subsequent incubation with L-Arginine. Finally, L-NAME strongly and significantly increased the drop in perfusion pressure and the area under the pressure trace following bolus of glyceryl trinitrate. These results suggest that in the mesenteric arterial bed of the rat, which can be considered as a resistant arteries preparation, basal tone appears to be controlled by a factor other than NO. Moreover, the vasodilator responses of muscarinic agonists are affected by L-NAME in their second late sustained phase only, which probably relies on a de novo synthesis of endothelium derived-NO. Finally, endothelium derived-NO exerts inhibitory effects both on the sensitivity of the vascular smooth muscle to glyceryl trinitrate and on the magnitude of its contraction in the presence of noradrenaline, two types of effects which are sensitive to L-NAME.

Animals↗
PubMed1993

Effect of VLDL on the inhibition of arachidonic acid transformation by dexamethasone in cultured smooth muscle cells.

Very-low-density lipoproteins (VLDL) induce a dose-dependent reduction (up to 55%) in the number of specific binding sites and about a 2-fold increase in binding affinity for [3H]dexamethasone in human and rat smooth muscle cells (SMC). Maximal effect of VLDL was achieved within 3-5 h at a lipoprotein concentration 60 micrograms protein/ml. Lipoprotein-mediated reduction in the number of [3H]dexamethasone binding sites resulted in partial loss of cellular sensitivity to hormone action: dexamethasone (1 x 10(-6) M) inhibited the transformation of [14C]arachidonic acid (AA) into metabolites to a lesser extent in SMC preincubated with VLDL (11.5%) than in untreated cells (29.0%). In particular, under these conditions the inhibitory effect of dexamethasone on prostaglandin I2 (PGI2) formation in VLDL-treated SMC was lower than in untreated cells (42.1% vs. 60%). We propose that VLDL is able to counteract the inhibitory effect of glucocorticoids on AA release and PGI2 formation in vascular SMC by reduction of cellular specific glucocorticoid binding sites.

Animals↗
PubMed1993

Semiquantitative study of the distribution of two cellular antigens by computer-directed color analysis.

BACKGROUND: The general way to differentiate objects in a field is to stain each of them specifically with a different dye, as the eye can easily discriminate colors. The use of specific dyes or immunohistochemical staining associated with an automated image analysis facilitates the quantitation of differently Colored objects. EXPERIMENTAL DESIGN: Rabbit aortic smooth muscle cells were seeded in culture conditions. When the cells reach confluence, they can be stained by immunocytochemistry. We were able to compare four different variables of immunostaining of two antigens in the same preparation. Antigenic expression was detected after double immunocytochemical staining, alkaline phosphatase, or peroxidase, and each antigen was stained sequentially by either enzyme. RESULTS: We have developed an approach to a nondestructive and noncolored limited quantitative method, that allows a strict analysis on the same view of two defined colors. We used the system of intensity, hue, and saturation to digitize colored video image. The distribution of these two antigens, alpha-actin and 2P1A2 both specific of smooth muscle cell, was quantitatively analyzed, and was not affected by the sequence of staining. CONCLUSIONS: This technique opens new possibilities for pathologists to compare antigenic distribution after immunocytochemical labeling. This can be extended to other dyes on histologic sections and to facilitate diagnosis.

Actins↗
PubMed1993

Synthesis of monohydroxylated fatty acids from linoleic acid by rat aortic smooth muscle cells and tissues: influence on prostacyclin production.

We have investigated whether cellular metabolism of linoleic acid (18:2) can influence prostacyclin (PGI2) production by cultured rat aortic smooth muscle cells (SMC) and tissues. Incubation of rat SMC homogenates with [1-14C]18:2 results in the enzymatic synthesis of [14C]13-HODE (hydroxyoctadecadienoic acid) and to a lesser extent [14C]9-HODE as defined by gas-liquid chromatography-mass spectrometry (GLC-MS). The observed changes, in percent enzymatically synthesized 13-HODE in the presence of indomethacin, aspirin, metyrapone, 15-HPETE (hydroperoxyeicosatetraenoic acid), and NDGA, suggest that it is formed from the PGH (prostaglandin endoperoxide) synthase pathway. Incubation of intact adherent SMC with [14C]linoleic acid demonstrates that the monohydroxylated compounds are predominantly esterified within the membrane phospholipids and not released into the incubation medium. The simultaneous incubation or a short-term preincubation of 18:2 and arachidonic acid (20:4) do not modify the enzymatic profile of 20:4 transformation. By contrast, long-term preincubation of cells with 18:2 or 13-HODE stimulates the transformation of exogenously added [14C]20:4 to [14C]6-keto PGF1 alpha. However, exogenous 13-HODE does not enhance [14C]6-keto PGF1 alpha recovery from [14C]20:4 prelabeled SMCs. Our results demonstrate that 18:2 is a substrate for PGH-synthase in rat aortic SMC and tissues. The 13-HODE formed is essentially esterified in cell phospholipids and remains without any significant effects on the release of [14C]6-keto PGF1 alpha from [14C]20:4 prelabeled SMC.

Animals↗
PubMed1992

Dual metabolic pathways of 12-HETE in rat aortic smooth muscle cells.

12(S)-HETE, a major lipoxygenase-derived compound from arachidonic acid is incorporated and metabolized by vascular smooth muscle cells via beta-oxidation. We have now identified for the first time in this cell type 12(S)-HETE metabolites formed by a combination of reductase and oxidation pathways. HPLC and GC-MS analysis of time-course experiments allow us to characterize two different metabolic pathways: a direct peroxisomal beta-oxidation of 12(S)-HETE leading to the formation of 16:3 (8-OH) which accumulates first and a reduction of one of the conjugated double bonds of 12(S)-HETE giving the dihydro-intermediate 20:3(12-OH) that transiently accumulates before being converted itself by peroxisomal beta-oxidation to 16:2(8-OH). Taken together these results may suggest that the transient accumulation of 20:3(12-OH) through transcellular metabolism of 12(S)-HETE may represent a part of the modulatory effect of 12(S)-HETE on vascular function.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1992

Effects of monohydroxylated fatty acids on arterial smooth muscle cell properties.

The hydroxylated derivatives of polyunsaturated fatty acids may be potent modulators of basic biological responses involved in pathological processes, including atherosclerosis. The object of the present investigation was to study the effects of monohydroxylated fatty acids (namely 12-HETE) on the properties of aortic smooth muscle cells (SMC) in culture. The changes in cell expression of differentiation antigen alpha-SM actin and 2P1A2 was followed by computerized morphometry, using specific monoclonal antibodies and the activation of cells by measuring cell motility. In addition, intracellular [Ca2+]i mobilization and IP3 formation were studied. Finally, the metabolic routes of monohydroxylated compounds and their effects on PGI2 secretion were reported. The results demonstrate that 12-HETE is able to stimulate the phenotypic modulation. PGI2 production and motility of arterial SMCs, despite any detectable activity in increasing [Ca2+]i or IP3 formation. By contrast with parent compounds 15-HETE and 13-HODE, which appear as potent prodifferentiating molecules, 12-HETE is specifically metabolized via a 10-11 reductase pathway in addition to the classical beta-oxidation pathway. Taken together, our results suggest that cellular metabolism of 12-HETE, produced by platelets in the vicinity of the arterial intima, and also by cells present inside the atherosclerotic intima, or associated with modified LDL may play a key role in the atherosclerotic process.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1991

Action of some salicylate derivatives on in vitro platelet aggregation. Inhibitory and inhibition antagonistic effects.

Twenty salicylate derivatives were tested for their antagonistic activity on the inhibitory effect of aspirin on platelet aggregation. The blocking effect was not limited to the salicylate but also characterised some of its substituted compounds. The substituant influence did not seem to be related to electronic or size parameters. This antagonistic activity of these derivatives decreased as concentrations increased, owing to the emergence of their own inhibitory activity: several salicylate derivatives showed dual inhibitory and inhibition antagonistic activity, with both properties present at the same concentration. A mechanism involving dissociated activities on the two enzymatic sites of cyclooxygenase is proposed.

Arachidonic Acid↗
PubMed1991

[Reactivity of the arterial wall to atherogenic stimuli].

Our understanding of the biological mechanism implicated in spontaneous or accelerated atherogenesis is steadily increasing. The vascular response to atherogenic stimuli implies activation of endothelial cells making possible the adhesion and then the migration of circulating mononuclear cells. When these cells are present in the intima they participate in the production of a number of factors liable to activate the migration and proliferation of the underlying smooth muscle cells (cytokines, growth factors, physiologically active lipids). The rupture of parietal homeostasis is discussed with reference to some experimental models in terms of intimal cellular recruitment and formation of foam cells which are the cardinal points of the initial pathogenic process.

Arteriosclerosis↗
PubMed1991

[Long-term induced effects by only one treatment with ketoconazole on rat tumoral pituitary cells (GH3/B6 strains)].

Ketoconazole, an imidazole is a powerful antimycotic that has recently been used in the treatment of endocrinological and lipid metabolism disorders as well as in anti-cancer chemotherapy. When rat mammosomatotropic cells are treated for 30 hrs., this drug produces different effects depending on whether cells are normal or tumoral (GH3/B6). A dose of 10 microM had no effect in normal cells, however, in tumoral cells it had dramatic effects: (i) 50% of the cells are killed and those which survive no longer proliferate and they secrete GH but not PRL; (ii) they respond to GHRH in a dose-dependent manner, while normal cells do not under similar culture conditions; (iii) the lipid composition of the membrane is modified as indicated by the increase in arachidonic acid turn-over and the dramatic change in the distribution of its metabolites. For the moment we cannot explain these data.

Animals↗
PubMed1990

Phenotypic expression of surface antigens of rabbit aortic smooth muscle cells in culture. Monoclonal antibody, 2P1A2, characteristic of smooth muscle cells present in atherosclerotic plaque, is not correlated with cell proliferation.

The expression of smooth muscle cell (SMC) antigens was studied in culture by immunofluorescence and immunoelectron microscopy. As specific SMC markers, we used 2 monoclonal antibodies (MAb), 1PC1 and 2P1A2 which are able to detect atherosclerotic plaques in the rabbit. MAb 1PC1 recognizes an antigen expressed on the cell surface, starting on the 7th day in primary culture after serum activation, and then secreted. On a confluent SMC monolayers this antigen appears outside the cell as an important filamentous network. The kinetics of secretion of this external protein recognized by 1PC1 corresponds to the kinetics of the secretory phenotype described by Chamley-Campbell and Campbell (Atherosclerosis, 40 (1981) 347). 2P1A2 MAb is specific for SMCs exclusively present in the rabbit atherosclerotic plaque. We studied the degree of reactivity of 2P1A2 with SMCs during primary cell culture. This "atherosclerotic" antigen of SMCs recognized by 2P1A2 is expressed in culture conditions by SMCs from rabbit normal media. This antigen appears after 3 days of serum activation, and heparin growth inhibition does not interfere with its expression. 2P1A2 recognized antigen is expressed during all cell cycle phases without amplification. 3 days after fetal calf serum (FCS) stimulation of cells which are in G0/G1, 89% are labelled by 2P1A2, 4 days later G0/G1 positive cells constitute 49%. We conclude that 2P1A2 immunolabelling on the SMC surface reflects an activated state which is not correlated with SMC proliferation.

Animals↗
PubMed1989

Prostacyclin-mediated effect of high density lipoproteins as cellular cholesterol acceptors on aortic smooth muscle cells.

Low (LDL) and high (HDL) density lipoproteins stimulate prostacyclin (PGI2) synthesis in cultured rabbit and human aortic smooth muscle cells. In this respect, the efficacy of HDL exceeded that of LDL, HDL3 being the most effective. HDL3 obtained from hypoalphacholesterolemic patients' serum had a lesser stimulative effect on PGI2 synthesis as compared with HDL3 of normolipidemic subjects. Partially purified apoprotein A-1 stimulates the metabolism of 14C-arachidonic acid accompanied with enhanced formation of prostaglandins, especially 6-keto-PGII alpha. Within a 24 h incubation in the fetal calf serum-free medium, prostaglandins I2 and E1 (1 x 10(-7) M) reduce the intracellular cholesterol level in human aortic smooth muscle cells by 30%. Total HDL fraction as well as HDL3 and HDL2b applied in combination with prostaglandins have a synergistic effect resulting in a 50% fall in intracellular cholesterol. Hypothetically, the uptake of cholesterol by HDL may include the following stages: (1) HDL interacts with the cell and activates the intracellular PGI2 synthesis probably via apo A-1 modulatory action on arachidonic acid metabolism; (2) newly synthesized PGI2 activates cholesteryl ester hydrolase leading to the formation of free cholesterol; (3) HDL takes up free cholesterol.

Adult↗
PubMed1989

Synthesis of hydroxy fatty acids from linoleic acid by human blood platelets.

The metabolism of linoleic acid by washed human platelets was investigated. [1.14C] linoleic acid was converted to [1.14C] hydroxy octadecadienoic acids (HODEs) at about the same rate with which [1.14C] 12-HETE was produced from [1.14C] arachidonic acid. The total radioactivity in HODEs was distributed among two isomers: 13-HODE (85%) and 9-HODE (15%) as defined by CG-MS. The production of HODEs by intact washed platelets was inhibited by indomethacin (IC50:5 x 10(-7) M) which suggest that hydroxy fatty acids were produced by PGH-synthase. By contrast, the production of HODEs by platelet cytosolic fractions was not modified under indomethacin treatment but completely abolished by NDGA (10(-3) M) and inhibited by the platelet lipoxygenase inhibitors 15-HETE (2.10(-5) M) and baicalein (10(-5) M). Platelets thus contain two different active systems which may convert linoleic acid to hydroxy fatty acids. Since these compounds remained essentially associated with the platelets, their presence may significantly participate in the mechanisms of platelet activation.

Arachidonate 15-Lipoxygenase↗
PubMed1989

Risk factors for myocardial infarction during coronary artery bypass graft surgery.

Patients with a particular thrombotic profile may be at greater risk of myocardial infarction during coronary artery bypass graft surgery. The thrombotic profile of 50 patients admitted to hospital with stable angina pectoris was determined prior to haemodynamic investigation. ECG results and determination of cardiac enzymes showed that 12 patients had suffered a perioperative myocardial infarction. These patients had a higher mean atherosclerotic score (42.1 +/- 10.5 vs 32.9 +/- 13, P less than 0.02), a longer aortic cross clamp time (59 +/- 15.2 vs 45.7 +/- 16.3 min, P less than 0.05), lower serum levels of protein C (101.2 +/- 26 vs 124.7 +/- 31.4%, P less than 0.05) and tissue plasminogen activator (322 +/- 580 vs 2307 +/- 2830 IU ml-1, P less than 0.01). There were no differences between the two groups in Jenkin's coronary score, the number and type of grafts, ejection fraction, left ventricular end-diastolic pressure, lipid profile or levels of markers of platelet release. In addition to a more severe distal coronary atheroma and a longer aortic cross-clamp time, patients with impaired endothelial fibrinolytic activity appeared to be at greater risk of myocardial infarction during coronary artery bypass graft surgery.

Aged↗
PubMed1989

Renin-angiotensin system in cultured human arterial smooth muscle cells.

Angiotensin converting enzyme (ACE) inhibitors were evaluated from their effects on human arterial smooth muscle cells in culture. [3H]ramipril binding has been determined in two different cell lines exhibiting ACE(+) and ACE(-) phenotypes. Specific binding occurred only in ACE(+) cells, was saturable, and displayed a Kd of 1 nM with a beta max value of 3.5 fmol/10(6) cells. Ramipril specific binding did not significantly modulate PGI2 synthesis in ACE(+) cells. By contrast, ramipril and, to a lesser extent, captopril appeared as weak inhibitors of PGI2 synthesis in ACE(-) cells. These data indicate that human arterial SMCs may express several phenotypes of the renin-angiotensin system under culture conditions and that ACE inhibitors may exert a non-renin-angiotensin-mediated pharmacological effect on eicosanoid synthesis.

Angiotensin-Converting Enzyme Inhibitors↗