In both type 2 diabetes and insulin-resistance syndromes, hyperglycemia and advanced glycation end products (AGEs) activate the transcription factor nuclear factor-kappaB (NF-kappaB) through a mechanism that partly involves the generation of reactive oxygen species (ROS). The contribution of hyperinsulinemia in this sequence has not been completely elucidated. In this work we investigated the actions of insulin and PPAR-gamma on the stimulation by AGEs of NF-kappaB protein expression in cultured aortic vascular smooth-muscle cells (VSMCs) from non-insulin-dependent diabetic rats and nondiabetic rats. The expression of proteins was evaluated with the use of Western immunoblotting. Incubations (24 hours) of VSMCs with 10 to 100 microg/mL glycated bovine serum albumin (AGE- BSA) increased NF-kappaB protein expression in both models. PPAR-gamma protein expression was only enhanced at concentrations of 500 to 1000 microg/mL (AGE-BSA). In the presence of insulin (10-100 nmol/L), the stimulation of NF-kappaB protein expression by AGE-BSA (100 microg/mL) was decreased, whereas the expression of PPAR-gamma, protein was enhanced. 15-Deoxyprostaglandin J2, a direct activator of PPAR-gamma, decreased AGE-BSA-stimulated NF-kappaB expression. These findings suggest that insulin decreases the incidence of alterations in VSMCs induced by AGEs through the reduction of NF-kappaB and an increase in PPAR-gamma protein expression (as far as the model could be extrapolated to in vivo situations). These data may help justify current therapeutic approaches involving the use of insulin and PPAR-gamma agonists.

OBJECTIVE:To assess the antioxidant/non-antioxidant effects of a hydroxytyrosol (HT)-rich phenolic extract from olive mill wastewaters administered with a breakfast.DESIGN, SETTING AND SUBJECTS:Five type I diabetic patients received 25 mg of HT the first day and 12.5 mg/day the following 3 days. Blood sampling was carried out at T(0) (baseline) and T(4d) just before the breakfast + HT administration and at time points 1, 2, 3 and 4 h after T(0). Urines (24-h) were collected from T(0) to T(4d). Baseline HbA1c was generally inferior to 10%, glycemia was within the range 6-24 mmol/l, whereas total cholesterol, HDL-chol and triglycerides were normal.RESULTS:The major finding was the 46% decrease in the serum TXB(2) production after blood clotting at T(4d). Plasma vitamin A, E, beta-carotene were not changed. Vitamin C tended to increase (P = 0.075). Plasma antioxidant capacity was enhanced at T(0)+1 h only, whereas its main determinants (albumin, bilirubin, uric acid) were not modified. Urinary 8-isoPGF(2alpha) levels were highly variable and were not affected significantly by HT administration.CONCLUSION:The major effect of HT accounts for an antiaggregating platelet action, leading to a possible prevention of thrombotic and microthrombotic processes.

Background Heme protein toxicity, owing to generation of reactive oxygen species most likely by direct interaction between heme iron and hydrogen peroxide (H2O2), may be involved in various pathologies, including atherogenesis and pigmentary acute renal failure. The aim of this study was to investigate the mechanism of heme cytotoxicity and the effects of antioxidant therapies in an in vitro model of heme-induced low-density lipoprotein (LDL) oxidation.Materials and methods Human LDLs were exposed to heme, iron (Fe), protoporphyrin (PPIX) and PPIX-Zinc (Zn) with or without H2O2. Lipid peroxidation was monitored by measurement of conjugated diene formation (at the 234-nm absorbance). The effect of various antioxidants, such as vitamin E and vitamin C, reduced glutathione (GSH), and oxidized glutathione (GSSG), mannitol and desferoxamine (DFO) was further investigated in the established in vitro model of LDL oxidation.Results Incubation of LDLs in the presence of heme/H2O2 induced lipid peroxidation with the optimal oxidation rate being at 5 mum heme/100 mum H2O2 doses. By contrast, incubation of LDL with H2O2, Fe, Fe/H2O2, PPIX, PPIX/H2O2, heme or PPIX-Zn did not initiate any LDL oxidation. In vitro, the vitamin E load protected native LDLs against heme/H2O2 oxidative modifications. Incubation of LDLs with increasing doses of vitamin C, GSH and DFO conferred a dose-dependent protection, while mannitol and GSSG had no effect.Conclusions Initiation and propagation of heme-induced lipid peroxidation is not mediated by a Fenton reaction but depends on specific interactions between heme and H2O2. It may result from the generation of ferryl and perferryl radicals derived from hemic Fe and H2O2 interactions. A protective effect of vitamins E, C, GSH and DFO was demonstrated in this model.

La troponine Ic (TnIc) est considérée comme un marqueur spécifique de lésion myocardique, largement utilisé dans le diagnostic de l'infarctus du myocarde (IDM) et présenterait un intérêt prédictif. Cette étude a pour but de comparer les valeurs de TnIc dosées sur l'ACCESS II® et sur l'IMMULITE Turbo® chez des patients à hauts risques cardiovasculaires. La troponine Ic a été déterminée chez 74 patients admis aux urgences pour une douleur thoracique (groupe I), 34 patients admis pour chirurgie vasculaire réglée (groupe II) et 39 diabétiques de type II (groupe III) avec plus de deux autres facteurs de risques cardiovasculaires. Les performances analytiques des deux méthodes sont comparables et largement compatibles avec les recommandations de l'IFCC. Toutefois, les discordances sont fréquentes pour le seuil d'alerte de l'IDM (5 sur 147 déterminations) pour le seuil du 99e percentile (29 sur 147 déterminations) et pour la SF (6 pour 147 déterminations). La majorité des discordances concerne le seuil du 99e percentile nécessitant un recours à une surveillance étroite, à l'inverse, le seuil non classique de la SF semble concordant pour les deux trousses et pourrait témoigner de l'absence de TnIc circulante.

La détermination de la bêta-2-microglobuline (β-2M) présente un intérêt bioclinique au cours des syndromes myéloprolifératifs, des maladies inflammatoires ou infectieuses et de l’insuffisance rénale chronique. Nous avons caractérisé les performances analytiques d’une technique immunochémiluminescente (Immulite® DPC, La Garenne Colombes) et d’une technique immunoturbidimétrique (Olympus®, Rungis). Ces méthodes ont été ensuite comparées avec la technique RIA (Immunotech®, Marseille) sur sérum, plasma, dialysat et urines chez 189 patients présentant (myélomes, dialysés, inflammations chroniques). Les performances analytiques sur tube sec des deux techniques non isotopiques sont comparables (répétabilité < 10 %, reproductibilité < 10 %, linéarité, r2> 0,99). Au sein de la population générale les résultats sont corrélés entre RIA–DPC (droite d’allométrie y = 0,648x + 0,0692 et r2= 0,84) et RIA–Olympus (droite d’allométrie y = 0,7172x – 0,34 et r2 = 0,94). Les performances analytiques sur tube hépariné pour les deux techniques non isotopiques sont comparables à celles obtenues sur tube sec (Olympus®, r2 = 0,93 ; DPC, r2= 0,75). Les résultats urinaires sont superposables pour les trois méthodes (RIA–DPC r2 = 0,97 et RIA–Olympus r2= 0,98). Cinquante-quatre dialysats ont pu être analysés (taux compris entre 0,46 et 2,91 mg/l), dans ces conditions les corrélations avec le RIA sont plus faibles (r2= 0,47 pour DPC et 0,54 pour Olympus®). Les performances analytiques des méthodes non isotopiques permettent son utilisation dans les laboratoires d’analyse médicale. Beta-2-microglobulin (β-2M) was determined in serum, urine and dialysate using immunochemiluminesce (Immulite DPC, La Garenne Colombes, France) and immunoturbidimetric assay (Olympus, Rungis, France) and was compared with radio-immunoassay (Immunotech, Marseille, France). One hundred and eighty-nine patients suffering from myeloma (N =66), end stage renal failure (N =54) or inflammation (N =69) were included in this study. On serum, immunochemiluminescence and immunoturbidimetric assays have reliable analytical performances. Values obtained with clinical samples are highly correlated to radio-immunoassay (DPC–RIA r2=0.84; Olympus–RIA r2=0.94) whatever the type of pathology. Values obtained with urinary samples (N =96) are closely related to those obtained with RIA (DPC–RIA r2 = 0.98; Olympus–RIA:r2=0.99). Despite the low levels observed in dialysate (N =57) good correlations between methods (DPC–RIA: r2=0.47; Olympus–RIA: r2=0.54 ; Olympus/DPC ; r2=0.85) are obtained. In conclusion, immunochemiluminescence or immunoturbidimetric assays could be used in routine chemistry in order to determine β2M in plasma, urine and dialysate.

Monitoring beta2-microglobulin (beta2M) in biological fluids has gained considerable interest in pathologies such as haematologic malignancies, renal diseases, and chronic inflammatory diseases. Due to limitations of the RIA in the routine laboratory, we measure beta2M with non-isotopic methods. 189 patients suffering from myeloma (n=66), end stage renal failure (n=54) or inflammation (n=69) were included in this study. beta2M was determined in serum, urine and dialysate using an immunoenzymometric assay with chemiluminescence detection [Immulite Diagnostic Products Corporation (DPC), La Garenne Colombes, France] and an immunoturbidimetric assay (Olympus, Rungis, France). The data were compared with a radioimmunoassay (Immunotech, Marseille, France) taken as a reference. Using serum samples, the immunoenzymometric assay with chemiluminescence detection and the immunoturbidimetric assay have reliable analytical performances. Values obtained with serum samples are highly correlated with the radioimmunoassay (DPC/RIA r2=0.84; Olympus/RIA r2=0.94) whatever the type of pathology; however an over-estimation which could be related to cross reactivity with beta2M fragments was observed with the RIA method as suggested by crossover calibration and recovery studies. Values obtained with urinary samples (n=96) are closely related to those obtained with the RIA (DPC/RIA r2 = 0.98; Olympus/RIA: r2=0.99). Despite the low levels observed in dialysate (n=57) good correlations were observed between Olympus vs DPC (r2=0.85). By contrast, the two non-isotope methods are poorly related with the RIA method (DPC vs RIA r2=0.47 and Olympus vs RIA r2=0.54). In conclusion, the immunoenzymometric assay with chemiluminescence detection or the immunoturbidimetric assay could be used in the routine laboratory in order to determine beta2M in plasma, urine and dialysate.

Background: Oxidative stress and alterations in lipid metabolism observed in hemodialysis patients potentiate the low-density lipoprotein (LDL) oxidability, recognized as a key event during early atherogenesis. Objective: To explore the effects of an oral vitamin E supplementation on oxidative stress markers and LDL oxidability in hemodialysis patients. Methods: Fourteen hemodialysis patients and six healthy volunteers were given oral vitamin E (500 mg/day) for six months. Oxidative stress was assessed using: plasma and lipoprotein vitamin E levels [high-performance liquid chromatography (HPLC) procedure]; thiobarbituric acid reactive substances (TBARS, Yaggi method); and copper-induced LDL oxidation. All parameters were evaluated before initiation of vitamin E supplementation, and at three and six months thereafter. Results: At baseline, a significantly higher TBARS concentration and a higher LDL oxidability were observed in hemodialysis patients when compared to controls. After six months of vitamin E supplementation, TBARS and LDL oxidability were normalized in hemodialysis patients. Conclusion: Our data confirm that hemodialysis patients are exposed to oxidative stress and increased susceptibility to ex vivo LDL oxidation. Since oral vitamin E supplementation prevents oxidative stress and significantly increases LDL resistance to ex vivo oxidation, supplementation by natural antioxidants such as vitamin E may be beneficial in hemodialysis patients.

OBJECTIVE: To investigate whether improvements in cardiovascular risk factors, as observed in energy-balance conditions after exchanging carbohydrates (CHO) for monounsaturated (MUFA) fats, are also observed in energy-restricted conditions. DESIGN: Longitudinal, clinical intervention study using two types of energy-restricted diets (−30% of initial energy intake) with similar levels of saturated and polyunsaturated fats: a high CHO diet (55% of energy from CHOs, 10% from MUFAs) and a high MUFA diet (40% of energy from CHOs, 25% from MUFAs). SUBJECTS: A total of 32 overweight subjects (nine males, 23 females, BMI: 26–45 kg/m 2 ). MEASUREMENTS: Body weight, serum lipids, fasting plasma insulin and phospholipid fatty acid composition of red blood cells were measured at baseline and after 8 weeks. Various oxidative status parameters (plasma lipid hydroperoxides, total plasma antioxidant capacity, plasma uric acid and vitamin E) and serum-induced smooth muscular cell (SMC) proliferation were also measured at these time points. RESULTS: Weight loss (1.1 kg/week over the first 4 weeks and 6.7 kg at week 8) was not significantly affected by the diet composition. Both diets reduced significantly total serum cholesterol, but the MUFA-rich diet showed better effects on fasting serum triacylglycerol (TG) than the CHO-rich diet: 1.18 vs 1.51 mmol/l for the MUFA-rich diet (after vs before, P <0.05) and 1.42 vs 1.62 for the CHO-rich diet. After 8 weeks, plasma vitamin E concentrations were positively associated with the oleic acid level of red blood cell phospholipids and showed opposite variations in both diets (increase with the MUFA-rich diet and decrease with the CHO-rich diet). Relative changes in SMC proliferation induced by sera were negatively associated with the ratio oleic:linoleic acid of red blood cell phospholipids and were significantly higher with the CHO-rich diet. CONCLUSIONS: The MUFA-rich diet showed better effects on serum TG than the CHO-rich diet, even with energy restriction and weight loss. The results suggest also a protective effect of oleic acid on oxidative stress and SMC proliferation, two other important cardiovascular risk factors.

OBJECTIVES:To investigate if supplementation of preterm infant formula with a high docosahexaenoic acid/eicosapentaenoic acid (DHA/EPA) ratio together with alpha-linolenic acid (ALA) was able to maintain plasma and red blood cell DHA levels similar to that obtained with breast milk feeding without altering n-6 fatty acid status.DESIGN AND SUBJECTS:Preterm infants of mothers who elected not to breast feed (n=13) were assigned to ALA- and DHA-enriched formula (DHA group: DHA/EPA=5/l). Infants fed breast milk (n=25) constituted a reference group (BM group). Anthropometric and fatty acid parameters (plasma phospholipids, cholesterol esters, triglycerides and red blood cell phosphatidylethanolamine, PL, CE, TG, RBC-PE, respectively) were obtained after 2 days (D2) and 15 days (D15) of enteral feeding and at the 37th week (W37) of post-conception age and 1 month later (W37+30) in the DHA group. Mean DHA intake ranged between 16.5+/-1.6 and 17.9+/-2.9 mg/kg/day between D2 and W37+30.RESULTS:At W37, infant weights, heights, and head circumferences were similar in DHA and BM groups. PL DHA was maintained in the DHA group at the same level as in the BM group and the same for DHA in PE at W37. In RBC-PE and at W37, AA status was the same in both groups. In PL, AA levels remained very stable throughout the study; however, in the DHA group AA levels in PL remained in the range observed with standard formulas.CONCLUSION:The combined 18:3 n-3 and DHA supplementation of infant formula with DHA/EPA ratio 5/l is compatible with growth and n-3 fatty acid metabolism similar to that of preterm infants fed human milk.

La C-reactive proteine (CRP) est consideree comme un marqueur de choix parmi les proteines de la phase aigue de l'inflammation. Plus recemment, la CRP haute sensibilite (CRP-hs) a ete utilisee pour la detection precoce d'infections neonatales et l'evaluation du risque de maladie coronarienne. Le dosage de la CRP ou de la CRP-hs necessite classiquement un prelevement sanguin sans anticoagulant alors que la majorite des analyses de biochimie de routine est realisee sur plasma heparine. Notre etude a pour but de comparer l'utilisation d'echantillons preleves sur tube heparine et sur tube sec pour le dosage de la CRP et de la CRP-hs par methode immunoturbidimetrique sur un automate Olympus. Les performances analytiques comprenant la linearite, le coefficient de variation, la surchage par de la CRP et les valeurs obtenues sur 185 echantillons ne sont pas affectees par le type de prelevement Le dosage de la CRP sur plasma permet de pratiquer cet examen sur les prelevements obtenus en routine, facilite la realisation de cet examen depuis l'equipe de soins jusqu'a l'equipe biologique.

To evaluate the relationship between the enzymatic Vitros assay for creatinine determination and other methods, we determined creatinine concentration in 400 heparin samples. Plasma creatinine level was successively determined on the Vitros 750 analyzer (Johnson & Johnson Co., Rochester, NY) and on the Olympus AU2700 analyzer (Olympus France, Rungis, France), using three reagents in the same assay: Olympus‐Jaffé and two enzymatic commercial kits—Crea Plus (Roche Diagnostics, Meylan, France) and Enzymatic Creatinine (Randox, Mauguio, France). Comparison of Jaffé and enzymatic measurements of plasma creatinine levels revealed a high correlation when considering all values ranged from 20–1,000 μmol/l (r > 0.99). However, for values <60 μmol/l, enzymatic reagents provided best results. Enzymatic methodology is a better clinical choice for the accurate measurement of creatinine, especially for neonates, pediatrics, and hematology units. Because analytical performance and the costs of Randox creatinine were satisfactory for our laboratory, this method, adapted on the Olympus analyzer, was chosen for routine determination of creatinine levels. According to the Valtec protocol (8), no interferences such as hemolysis, lipemia, or bilirubin were detected for Enzymatic Creatinine Randox. J. Clin. Lab. Anal. 17:235–240, 2003. © 2003 Wiley‐Liss, Inc.

A large body of evidence supports the key role of oxidized low-density lipoprotein in atherosclerosis. The aim of this study was to compare the capacity of natural polyphenols (PP) from Vitis vinifera and Olea europea at protecting LDL against oxidation brought about by Cu2+, oxygen-centered radical-generating AAPH, or peroxynitrite-generating SIN-1 in vitro systems, or at impairing superoxide production in promonocyte cells (THP-1) conveniently differentiated into adherent macrophages. PP were either from the whole grape (fraction A) containing mainly procyanidins, (epi)-catechin and anthocyanins, or from grape seed extracts (fractions B and C) consisting of tannins and procyanidin oligomers with a higher content in B than in C, or from a grape skin extract (fraction D) consisting mainly of anthocyanins, or from a hydrosoluble olive mill wastewater PP extract (fraction E) containing hydroxytyrosol and oleuropein. Chlorogenic acid (F) and catechin (G) were taken as archetypes of PP preventing oxidation partly as copper scavenger and as radical scavenger only, respectively. All grape fractions were efficient towards Cu2+ system (equally or more efficient than F), whereas they were rather poorly efficient towards AAPH and SIN-1 (less efficient than G but as efficient as F). Among the PP fractions, B was the most effective at protecting LDL in the SIN-1 system and at impairing THP-1 superoxide production. Taken together, these data suggest that the PP fraction from grape seed rich in procyanidins achieves the best compromise between the direct and indirect (i.e. cell-mediated) types of action in protecting LDL against oxidation, strengthening the need for improving the knowledge of its bioavailability in humans.

Determination of C-reactive protein (CRP) and high-sensitivity CRP (hs-CRP), markers of systemic inflammation and atherosclerosis risk, usually requires serum samples, while heparin plasma samples are routinely collected for routine chemistry. This study evaluates the use of heparin plasma samples for hs-CRP and CRP determinations using immunoturbidimetric methods on an Olympus system. As a result, analytical performance, including linearity, imprecision values, and determination from 185 clinical samples, are not affected by the type of sampling, validating the use of heparin plasma samples for CRP and hs-CRP determination with Olympus reagents.

The purpose of this double clinical study was (1) to evaluate the effect of one single intake (300 ml) of red wine (RW) on the plasma antioxidant capacity (pAOC) and plasma phenolics over the 24-h time period following the intake, and (2) to compare the long-term effects of daily intakes (250 ml/d) of RW, white wine (WW) and Champagne (CH) on the plasma and LDL characteristics of healthy sujects. In the first part, blood samples were collected just before and after wine consumption. In the second part, subjects received the 3 types of wine successively, only at the mealtime, over 3-week periods separated by a 3-week wash out. Blood samples were drawn in fasting condition before and after each 3-week wine consumption period. The peak of pAOC was at 3-4 h following the single intake of RW, that of catechin was at 4 h (0.13 μmol/l) and that of gallic acid and caffeic acid was earlier (≤⃒1.5 and 0.3 μmol/l, respectively). In plasma, the major form of gallic acid was 4-O-methylated, but a minor form (the 3-O-methyl derivative) appeared. In the long term study, no wine was able to change LDL oxidizability, but some other parameters were modified specifically: RW decreased pAOC (without changing TBARS and uric acid plasma levels), LDL lipids and total cholesterol (TC), and increased plasma apoA1, whereas CH increased plasma vitamin A. The beneficial effect of RW seems to mainly be explained by its action on lipid and lipoprotein constants, and not by its antioxidant one.

BACKGROUND Enhanced oxidative stress in haemodialysis (HD) patients may be considered as a risk factor for accelerated atherosclerosis. Reduced antioxidant defences include impairment in enzyme activities and decreased plasma levels of hydrophilic vitamin C (vit C), and cellular levels of lipophilic vitamin E (vit E). METHODS We investigated plasma levels of vit C in 19 patients undergoing regular haemodiafiltration (HDF) (mean age 62+/-7 years) and in 1846 healthy elderly subjects (HS) (mean age 69+/-5 years). The contribution of convection and diffusion was determined using paired filtration dialysis (PFD), a modified HDF technique which physically separates convective from diffusive fluxes. Blood samples were collected before and after the HDF session; in addition at 60 min of HDF, samples were drawn from arterial lines (AL) and venous lines (VL), dialysate (D) and ultrafiltrate (UF). Blood levels of total vit C were determined using an HPLC fluorescence method. Markers of oxidative stress were also assessed in both populations as follows: levels of malondialdehyde (MDA) were determined by fluorometric assay, measurements of advanced oxidation protein products (AOPP) and glutathione peroxidase (GSH-Px) activity were performed by spectrophotometric assay, and plasma vit E content was obtained by an HPLC procedure. RESULTS A significant reduction in plasma vit C level was observed in HDF patients when compared with HS (1.6+/-1.4 microg/ml in HDF vs 6.6+/-3.7 microg/ml in HS; P<0.01). The HDF session was associated with a dramatic reduction in vit C levels (1.87+/-1.57 microg/ml before HDF and 0.98+/-0.68 microg/ml after HDF); at 60 min of HDF, concentrations were as follows: AL=1.35+/-1.27 microg/ml; VL=0.37+/-0.31 microg/ml, D=0.40+/-0.34 microg/ml, UF=1.24+/-1.18 microg/ml; corresponding to a diffusive flux of 271 microg/min and a convective flux of 126 microg/min. Total loss of vit C could be assessed at 66 mg/session (8--230 mg/session). According to this loss of vit C, presence of an oxidative stress was demonstrated in HD population as shown by a significant increase in MDA (1.66+/-0.27 microM in HD vs 0.89+/-0.25 microM in HS; P<0.01) and AOPP (77.5+/-29.3 microM in HD vs 23.5+/-13.2 microM in HS; P<0.01) levels, and a decrease in GSH-Px activity (259.2+/-106.3 U/l in HD vs 661.2+/-92.2 U/l in HS; P<0.01). No change in plasma vit E between both populations (30.7+/-9.1 microM in HD vs 35.3+/-7.34 microM in HS) was observed. CONCLUSIONS These results suggest that HDF with highly permeable membranes is associated with a significant loss of vit C. Diffusive transport is responsible for two-thirds whereas convective phenomenon accounts for only one-third of this loss.

Oxidized low density lipoprotein (LDL) plays an important role in atherogenesis. It is generally thought that LDL is mainly oxidized in the intima of vessel walls, surrounded by hydrophilic antioxidants and proteins such as albumin. The aim of this study was to investigate the possible interrelationships between oxidation resistance of LDL and its protein and lipid moieties. Proteins and to a lesser extent lipids, appeared to be the major determinants in the LDL Cu 2+ -oxidation resistance, which in turn depend on the ultracentrifugation (UC) procedure used. Comparing high speed/short time (HS/ST, 4 u h), high speed/long time (HS/LT, 6-16 u h) and low speed/long time (LS/LT, 24 u h) conditions of UC, HS with the shortest time (4 u h) led to prepare LDL (named LDL·HS-4 u h) with higher total protein and triglyceride contents, unchanged total cholesterol, phospholipids and Vitamin E, and higher Cu 2+ -oxidation resistance. Among proteins, only albumin allows to explain changes. PAF acetyl hydrolase appeared to be unaffected, whereas its pro-oxidant role was established and found only in the absence of albumin. In contrast the pro-oxidant role of caeruloplasmin took place regardless of the albumin content of LDL. The antioxidant effect of albumin (the oxidation lag time was doubled for 20 u mol/mol albumin per LDL) is assumed to be due to its capacity at decreasing LDL affinity for Cu 2+ . Interestingly, the LDL·HS-4 u h albumin content mirrored the intrinsic characteristics of LDL in the plasma and was not affected by added free albumin. Moreover, it has been verified that in 121 healthy subjects albumin was the best resistance predictor of the Cu 2+ -oxidation of LDL·HS-4 u h, with a multiple regression equation: lag time (min)=62.1+0.67(HSA/apoB)+0.02 (TG/apoB) m 0.01(TC/apoB); r =0.54, P <0.0001. Accounted for by lag time, the oxidation resistance did not correlate with f -tocopherol and ubiquinol contents of LDL. The mean albumin content was about 10 u mol/mol, and highly variable (0-58 u mol/mol) with subjects. The LDL·HS-4 u h may account for the status of LDL in its natural environment more adequately than LDL resulting from other conditions of UC.

Expression of antioxidant enzymes (AOE), an important mechanism in the protection against oxidative stress, could be modified by the redox status of the cells. The aim of this project was to evaluate the role of vitamin E deficiency in association with a high-cholesterol diet in the hepatic lipid peroxidation and the expression of AOE. Two groups of 6 male rats were fed with a high-cholesterol or a high-cholesterol vitamin E-deficient diet. All animals were sacrificed at 72 days of treatment. Liver lipid peroxidation index (Malondialdehyde; MDA) and hepatic AOE were evaluated. Total liver RNA was extracted, and the steady state messenger RNA (mRNA) levels of glutathion peroxydase, manganese superoxide dismutase, Cu/Zn superoxide dismutase and catalase were examined by northern blot. After 72 days on the diet, a significant increase in the lipid peroxidation index was observed in the vitamin E deficient group (MDA : 4.45 +/- 0.29 nmol/mg protein versus 3.65 +/- 0.1 nmol/mg protein in vitamin E normal group). Despite this oxidative stress, the activities and mRNA levels of liver AOE were not significantly different in the 2 groups. These preliminary results show that chronic vitamin E deficiency associated with high cholesterol diet is able to increase lipid peroxidation without modulation of AOE expression and activity in the liver. This suggests that beneficial effects of dietary vitamin E are due to a plasma antioxidant effect or a cell mediated action, rather than to a specific modulation of cellular enzymes.

Specific antioxidant activity (SAA) (i.e., activity related to the molar or gallic acid equivalent amount of antioxidant) of natural polyphenolic mixtures or pure phenolic compounds was studied using their capacity to delay the conjugated diene production brought about by in vitro LDL copper-mediated or AAPH-mediated oxidation. The cinnamic acid series (caffeic, sinapic, ferulic acids) displayed a constant SAA over a large range of concentrations, whereas the benzoic acid series (gallic and protocatechuic acids) showed much higher SAA at low concentrations. The natural phenolic mixtures had a constant SAA. The highest SAA was obtained with caffeoyl esters (caffeoylquinic, rosmarinic, and caffeoyltartaric acids) and catechin for the copper-oxidation and the AAPH-oxidation system, respectively. Phenolic mixtures and acids delayed vitamin E depletion and decreased proinflammatory lysophosphatidylcholine production. As with polyphenols, probucol delayed lysophosphatidylcholine and conjugated dienes production, at higher concentrations, but was not effective at preventing vitamin E depletion. Polyphenols prevent the oxidation of LDL and its constituents (vitamin E, phosphatidylcholine), which is compatible with an antiinflammatory and antiatherosclerotic role in pathophysiological conditions.

Le stress oxydant est le resultat d'un desequilibre au sein d'un meme organisme entre la production d'especes reactives de l'oxygene et les mecanismes de defense. Ce desequilibre, dont les multiples consequences touchent aussi bien les acides nucleiques que les proteines ou les lipides, peut provenir soit d'une production exageree de radicaux libres, soit d'une alteration des mecanismes de defense. Evaluer le stress oxydant c'est donc estimer la production de radicaux libres, apprecier les mecanismes de defense et enfin quantifier les produits secondaires qui peuvent en resulter. Dans un premier temps, nous ferons un bref rappel sur l'origine et la production des differents oxydants, avec une attention particuliere a la NADPH oxydase. Cette enzyme et la production des Formes Reactives de l'Oxygene (FRO) consecutive a son activation semblent largement impliquees dans le developpement de nombreuses pathologies ayant une composante inflammatoire ou des pathologies associees au viellissement. Par la suite, nous envisagerons comment la regulation de la NADPH oxydase pourrait donc etre une cible therapeutique privilegiee dans la prevention de ces maladies.