Myeloperoxidase-catalyzed oxidation of cyanide to cyanate: A potential carbamylation route involved in the formation of atherosclerotic plaques?

Protein carbamylation by cyanate is a post-translational modification associated with several (patho)physiological conditions, including cardiovascular disorders. However, the biochemical pathways leading to protein carbamylation are incompletely characterized. This work demonstrates that the heme protein myeloperoxidase (MPO), which is secreted at high concentrations at inflammatory sites from stimulated neutrophils and monocytes, is able to catalyze the two-electron oxidation of cyanide to cyanate and promote the carbamylation of taurine, lysine, and low-density lipoproteins. We probed the role of cyanide as both electron donor and low-spin ligand by pre-steady-state and steady-state kinetic analyses and analyzed reaction products by MS. Moreover, we present two further pathways of carbamylation that involve reaction products of MPO, namely oxidation of cyanide by hypochlorous acid and reaction of thiocyanate with chloramines. Finally, using an in vivo approach with mice on a high-fat diet and carrying the human MPO gene, we found that during chronic exposure to cyanide, mimicking exposure to pollution and smoking, MPO promotes protein-bound accumulation of carbamyllysine (homocitrulline) in atheroma plaque, demonstrating a link between cyanide exposure and atheroma. In summary, our findings indicate that cyanide is a substrate for MPO and suggest an additional pathway for in vivo cyanate formation and protein carbamylation that involves MPO either directly or via its reaction products hypochlorous acid or chloramines. They also suggest that chronic cyanide exposure could promote the accumulation of carbamylated proteins in atherosclerotic plaques.

Impact of myeloperoxidase-LDL interactions on enzyme activity and subsequent posttranslational oxidative modifications of apoB-100.

Oxidation of LDL by the myeloperoxidase (MPO)-H2O2-chloride system is a key event in the development of atherosclerosis. The present study aimed at investigating the interaction of MPO with native and modified LDL and at revealing posttranslational modifications on apoB-100 (the unique apolipoprotein of LDL) in vitro and in vivo. Using amperometry, we demonstrate that MPO activity increases up to 90% when it is adsorbed at the surface of LDL. This phenomenon is apparently reflected by local structural changes in MPO observed by circular dichroism. Using MS, we further analyzed in vitro modifications of apoB-100 by hypochlorous acid (HOCl) generated by the MPO-H2O2-chloride system or added as a reagent. A total of 97 peptides containing modified residues could be identified. Furthermore, differences were observed between LDL oxidized by reagent HOCl or HOCl generated by the MPO-H2O2-chloride system. Finally, LDL was isolated from patients with high cardiovascular risk to confirm that our in vitro findings are also relevant in vivo. We show that several HOCl-mediated modifications of apoB-100 identified in vitro were also present on LDL isolated from patients who have increased levels of plasma MPO and MPO-modified LDL. In conclusion, these data emphasize the specificity of MPO to oxidize LDL.

Exposure of endothelial cells to physiological levels of myeloperoxidase-modified LDL delays pericellular fibrinolysis.

BACKGROUND: Blood fluidity is maintained by a delicate balance between coagulation and fibrinolysis. The endothelial cell surface is a key player in this equilibrium and cell surface disruptions can upset the balance. We investigated the role of pericellular myeloperoxidase oxidized LDLs (Mox-LDLs) in this balance. METHODS AND RESULTS: We designed a technical device that enabled us to monitor fibrinolysis in real-time at the surface of an endothelial cell line (EA.hy926), and showed that Mox-LDL decreased pericellular fibrinolysis. There were no changes in fibrinolysis when EA.hy926 endothelial cells were exposed to native LDL (24 hours) at doses of 10, 50, 100 and up to 1250 µg/ml. However, treatment of EA.hy926 endothelial cells with 10 and 50 µg/ml of Mox-LDL (physiological serum concentrations) increased the lysis time by 15 and 13%, respectively (p<0.001), although this effect was not present at higher concentrations of 100 µg/ml. This effect was not correlated with any changes in PAI-1 or t-PA or PA Receptor (PAR) expression. No effect was observed at the surface of smooth muscle cells used as controls. CONCLUSION: Our data link the current favorite hypothesis that modified LDL has a causal role in atheroma plaque formation with an old suggestion that fibrin may also play a causal role. Our data help complete the paradigm of atherosclerosis: Modified LDL locally enhances fibrin deposition (present work); fibrin deposits enhance endothelial permeability; this effect allows subendothelial accumulation of lipid and foam cells.

Safety of a fixed-dose combination of fenofibrate/pravastatin 160 mg/40 mg in patients with mixed hyperlipidaemia: a pooled analysis from a database of clinical trials.

BACKGROUND: Fenofibrate can be prescribed concomitantly with an HMG-CoA reductase inhibitor (statin) to improve achievement of lipid goals in patients with atherogenic mixed hyperlipidaemia. However, some safety concerns, particularly an increased risk of myopathy, have been reported when these drugs are taken together. OBJECTIVE: The aim of this analysis was to assess the general safety and tolerability of a fenofibrate/pravastatin (FF/PRA) 160 mg/40 mg fixed-dose combination (FDC) capsule based on a pooled database of phase III clinical trials in patients with mixed hyperlipidaemia. METHODS: Safety data were pooled from five phase III studies (four double-blind with an uncontrolled extension and one open) of ≥12 to 64 weeks' duration. Adverse event (AE) profiles of FF/PRA 160 mg/40 mg (n=645 in the double-blind cohort) were evaluated relative to comparators (statins, n=519 or fenofibrate, n=122). Absolute incidence rates were calculated in both the double-blind cohort and the all-studies cohort (FF/PRA 160 mg/40 mg, n=1566) for all AEs, drug-related AEs, serious AEs, discontinuations due to AEs, AEs of specific interest including abnormal laboratory data, and deaths. RESULTS: The frequency and/or intensity of overall AEs, drug-related AEs, serious AEs and discontinuations due to AEs were not significantly increased for the FDC (36.0%, 12.3%, 1.7% and 5.1%, respectively) versus the statin (28.7%, 8.9%, 0.8% and 2.7%, respectively) and fenofibrate (59.0%, 21.3%, 0% and 4.9%, respectively) monotherapies. No deaths were reported during the course of treatment in clinical trials. Nevertheless, three deaths were reported more than 30 days after the patients completed the study; none of these deaths were assessed as being related to FF/PRA 160 mg/40 mg treatment. Among the AEs of special interest, no myopathy or rhabdomyolysis were reported; no patients were considered to have experienced a drug-induced liver injury; no case of pancreatitis occurred in the double-blind cohort and four patients reported pancreatitis in the all-studies cohort, two of them being study-treatment related; no case of pulmonary embolism was reported in the double-blind cohort and two patients presented with pulmonary embolism, unrelated to the study drug, in the all-studies cohort; there were more cases of decreased creatinine clearance in the FF/PRA 160 mg/40 mg group (1.7%) than in the statin group (0.6%). CONCLUSION: Within the limitations of this database (notably low percentage of very elderly patients, limited sample size of patients with mild renal insufficiency, and mode of selection in the clinical trials), no particular safety concern was raised with FF/PRA 160 mg/40 mg in the double-blind cohort as compared with statin and fenofibrate monotherapies. The acceptable long-term safety profile of FF/PRA 160 mg/40 mg was confirmed with a low frequency of AEs of interest, comparable to that observed in the 12-week double-blind cohort. Emergent effects possibly related to FF/PRA 160 mg/40 mg were mainly those attributable to fenofibrate (decrease in creatinine clearance and pancreatitis).

Long-term safety and efficacy of fenofibrate/pravastatin combination therapy in high risk patients with mixed hyperlipidemia not controlled by pravastatin monotherapy.

OBJECTIVE: To assess the long-term safety and efficacy of a fenofibrate/pravastatin 160/40 mg fixed-dose combination in high-risk patients with mixed hyperlipidemia not controlled by pravastatin 40 mg monotherapy. STUDY DESIGN AND METHODS: After an 8-week pravastatin 40 mg and diet run-in period, high-risk patients (n = 248) with low-density lipoprotein cholesterol (LDL-C) ≥ 100 mg/dL and triglycerides (TG) ≥ 150 and ≤400 mg/dL, were randomized to fenofibrate/pravastatin combination therapy or to pravastatin monotherapy for 12 weeks, followed by an open-label, 52-week safety phase on the combination therapy. RESULTS: Of the 224 patients who continued after the double-blind phase, 211 completed the one-year safety period. Overall, fenofibrate/pravastatin combination therapy was well tolerated during this extension study. Only three patients had an elevation of ALAT > 3 times the upper limit of normal and one patient a CPK elevation ≥5, but <10 times the upper limit of normal. At week 64, and by comparison to baseline levels on pravastatin 40 mg, the fenofibrate/pravastatin combination therapy significantly reduced non-high-density lipoprotein (non-HDL) cholesterol by 16.3%, LDL-C by 12.2%, TG by 31.6%, apolipoprotein B by 11.0% and increased HDL-cholesterol and apolipoprotein A1 respectively by 4.8 and 9.6% (p < 0.0001 for all the variables). A limitation of this trial is that the study was not powered to assess clinical events. CONCLUSIONS: Long-term co-administration of fenofibrate/pravastatin 160/40 mg in a single capsule was well tolerated and produced complementary benefits on the overall lipid profile of high-risk patients with mixed hyperlipidemia not controlled by pravastatin 40 mg.

Optimization of apolipoprotein-B-100 sequence coverage by liquid chromatography-tandem mass spectrometry for the future study of its posttranslational modifications.

Proteomic applications have been increasingly used to study posttranslational modifications of proteins (PTMs). For the purpose of identifying and localizing specific but unknown PTMs on huge proteins, improving their sequence coverage is fundamental. Using liquid chromatography coupled to mass spectrometry (LC-MS/MS), peptide mapping of the native apolipoprotein-B-100 was performed to further document the effects of oxidation. Apolipoprotein-B-100 is the main protein of low-density lipoprotein particles and its oxidation could play a role in atherogenesis. Because it is one of the largest human proteins, the sequence recovery rate of apolipoprotein-B-100 only reached 1% when conventional analysis parameters were used. The different steps of the peptide mapping process-from protein treatment to data analysis-were therefore reappraised and optimized. These optimizations allowed a protein sequence recovery rate of 79%, a rate which has never been achieved previously for such a large human protein. The key points for improving peptide mapping were optimization of the data analysis software; peptide separation by LC; sample preparation; and MS acquisition. The new protocol has allowed us to increase by a factor of 4 the detection of modified peptides in apolipoprotein-B-100. This approach could easily be transferred to any study of PTMs using LC-MS/MS.

Structure-based design, synthesis, and pharmacological evaluation of 3-(aminoalkyl)-5-fluoroindoles as myeloperoxidase inhibitors.

Oxidized low-density lipoproteins (LDLs) accumulate in the vascular wall and promote local inflammation, which contributes to the progression of the atheromatous plaque. The key role of myeloperoxidase (MPO) in this process is related to its ability to modify APO B-100 in the intima and at the surface of endothelial cells. A series of 3-(aminoalkyl)-5-fluoroindole analogues was designed and synthesized by exploiting the structure-based docking of 5-fluorotryptamine, a known MPO inhibitor. In vitro assays were used to study the effects of these compounds on the inhibition of MPO-mediated taurine chlorination and oxidation of LDLs. The kinetics of the interaction between the MPO redox intermediates, Compounds I and II, and these inhibitors was also investigated. The most potent molecules possessed a 4- or 5-carbon aminoalkyl side chain and no substituent on the amino group. The mode of binding of these analogues and the mechanism of inhibition is discussed with respect to the structure of MPO and its halogenation and peroxidase cycles.

Efficacy and safety of adding fenofibrate 160 mg in high-risk patients with mixed hyperlipidemia not controlled by pravastatin 40 mg monotherapy.

Patients with mixed hyperlipidemia and at high risk of coronary heart disease may not achieve recommended low-density lipoprotein (LDL) and non-high-density lipoprotein (non-HDL) cholesterol goals on statin monotherapy. This study was designed to evaluate the efficacy and safety of a fenofibrate 160 mg/pravastatin 40 mg fixed-dose combination therapy in high-risk patients not at their LDL cholesterol goal on pravastatin 40 mg. In this 12-week, multicenter, randomized, double-blind, double-dummy, parallel-group study, after a run-in on pravastatin 40 mg, 248 patients were randomly assigned to fenofibrate/pravastatin combination therapy or to pravastatin monotherapy. Combination therapy produced significantly greater complementary decreases in non-HDL cholesterol (primary end point) than pravastatin monotherapy (-14.1% vs -6.1%, p = 0.002). Significantly greater improvements were also observed in LDL cholesterol (-11.7% vs -5.9%, p = 0.019), HDL cholesterol (+6.5% vs +2.3%, p = 0.009), triglycerides (-22.6% vs -2.0%, p = 0.006), and apolipoprotein B (-12.6% vs -3.8%, p <0.0001). Significantly more patients receiving the fenofibrate/pravastatin combination therapy than pravastatin alone achieved the LDL cholesterol (<100 mg/dl) and non-HDL cholesterol (<130 mg/dl) goals (p <0.01). Combination therapy was generally well tolerated with incidences of clinical and laboratory adverse experiences similar between the 2 groups. In conclusion, the fenofibrate 160 mg/pravastatin 40 mg fixed-dose combination therapy significantly improved the global atherogenic lipid profile in high-risk patients with mixed hyperlipidemia not controlled by pravastatin 40 mg monotherapy.

Effects of raloxifene treatment on the phenotype of blood monocytes.

Raloxifene (RLX), a selective oestrogen receptor modulator, has oestrogen-agonist effects on bone, lipoproteins, and homocysteine and oestrogen-antagonist activity in the breast and uterus, positioning it as a potential drug for long-term prevention of coronary heart disease in postmenopausal women. To further evaluate its influence on cardiovascular risk factors, we studied the effects of 60 mg/day RLX on serum lipid levels, inflammatory (high-sensitivity C-reactive protein, and coagulation (fibrinogen) markers, monocytes, and fibrinolysis in 15 healthy postmenopausal women. Markers were measured at baseline, after 1 month without treatment, and after 3 months of treatment. Fibrinolysis was evaluated using the euglobulin clot lysis time (ECLT) determined with a new semiautomatic optical method. Monocyte phenotype was determined by measurement of the expression of the antigens CD14, HLA-DR, and CD62-L using flow cytometry. After 3 months of RLX treatment, we observed a decrease in total cholesterol (p = 0.002), in low-density lipoprotein cholesterol (p <0.001), and in lipoprotein A (p = 0.01). Fibrinogen (p = 0.002) decreased significantly, and high-sensitivity C-reactive protein had a tendency to decrease, but this did not reach statistical significance (p = 0.06). RLX treatment had no effect on ECLT (p = 0.223) or on white blood cell, lymphocyte, and total monocyte counts (p = 0.313). Monocyte expression of HLA-DR, CD14, and CD62-L was not modified by the treatment. In conclusion, we confirm that RLX has beneficial short-term effects on levels of lipids and inflammatory markers, with no effect on fibrinolysis or monocyte phenotype.

Effects of phosphodiesterase inhibitors on the inflammatory response of endothelial cells stimulated by myeloperoxidase-modified low-density lipoprotein or tumor necrosis factor alpha.

BACKGROUND: Sildenafil, vardenafil, and tadalafil are phosphodiesterase type 5 inhibitors (PDE5-Is) usually used in the treatment of erectile dysfunction (ED). Previously, we have shown the presence of myeloperoxidase-modified low-density lipoprotein (Mox-LDL) in the penises of patients with ED, and we have shown the impact of Mox-LDL on cyclic monophosphate (cGMP) level. In vitro, Mox-LDL triggered the inflammatory response by increasing the release of both interleukin 8 (IL-8) and tumor necrosis factor alpha (TNF-alpha) by endothelial cells (ECs) and monocytes respectively. OBJECTIVE: To determine whether or not the three therapeutically PDE5-Is protect against the proinflammatory effects of Mox-LDL or TNF-alpha on ECs. DESIGN, SETTING, AND PARTICIPANTS: ECs (EA.hy926) were incubated in the presence of either TNF-alpha (100 pg/ml) or Mox-LDL (200 microg/ml) with each of the three PDE5-Is (1 microM, 5 microM, and 10 microM) respectively. IL-8 production was measured in the supernatant after 48 h of incubation. MEASUREMENTS: All experiments were repeated at least three times. Statistical analysis was performed with an ANOVA. RESULTS AND LIMITATIONS: Two-way ANOVA analysis showed that TNF-alpha alone (p<0.001) or Mox-LDL alone (p<0.001) increased IL-8 production. Sildenafil, vardenafil, or tadalafil alone did not generate an increase of IL-8 production. Tadalafil in combination with Mox-LDL and TNF-alpha showed a decrease of IL-8 (p<0.05) compared with sildenafil and vardenafil. CONCLUSIONS: Among the three available PDE5-Is, tadalafil showed an additional potentially anti-inflammatory effect on relaxation. Those data could be considered for the chronic use of PDE5-Is, but extrapolations of experimental evidence to the clinical setting should be made cautiously.

Coronary stenting is associated with an acute increase in plasma myeloperoxidase in stable angina patients but not in patients with acute myocardial infarction.

BACKGROUND: Myeloperoxidase (MPO) has emerged as a critical mediator in the physiopathology of atherosclerosis from plaque formation and growth until destabilization and rupture leading to acute coronary syndrome (ACS). Using coronary stenting as a model of plaque injury, we aimed to determine the evolution of systemic MPO levels following coronary stenting in stable angina patients and in patients with acute myocardial infarction (AMI). METHODS: Plasma levels of MPO, lactoferrin, interleukin (IL)-6, C-reactive protein and PMN counts were assessed in 13 patients with Non-ST-elevation myocardial infarction (NSTEMI) (Group A) and in 29 patients with stable angina pectoris (Group B), undergoing coronary stenting. Serial blood samples were taken before angioplasty (baseline) and at 1, 6 and 24 h following initial balloon inflation. RESULTS: Following angioplasty, the overall plasma MPO levels significantly increased at 1 h in group B (120.5+/-79.0 to 166+/-79.5, p=0.003) but not in group A (121+/-63.4 to 124.7+/-76.9, p=0.753). In Group B, the increase in MPO levels at 1 h were significantly higher in the presence of complex lesions compared to patients with simple lesions (p=0.023). Lactoferrin levels showed no change over time except for a significant decrease at 6 h in group B. CONCLUSIONS: In stable angina patients, coronary stenting is associated with an acute and transient increase in plasma MPO levels, but not in lactoferrin levels, with an enhanced response in the presence of complex lesions. In contrast, we observed no changes in plasma MPO and lactoferrin levels following stenting in patients with AMI. Given its pro-inflammatory properties, the potential implication of MPO release on clinical outcome in stable patients undergoing stenting needs further investigation.

Belgian expert opinion: how to reduce the residual risk in atherogenic dyslipidaemic patients: place of fibrates.

The demographics of dyslipidaemia have changed towards a more complex atherogenic dyslipidaemia involving increased levels of LDL-C, in particular highly atherogenic small dense particles, hypertriglyceridaemia and low HDL, together with increased levels of markers of cardiovascular inflammation, thrombogenesis and endothelial dysfunction. Statins were shown to significantly lower cardiovascular morbidity and mortality, but there still remains a high residual risk in dyslipidaemic patients, in particular with metabolic syndrome, type 2 diabetes, or low HDL levels. Fibrates have been shown to reduce plasma triglycerides and increase HDL-C, while improving inflammation, thrombogenesis and endothelial dysfunction. Clinical trials with fibrates have demonstrated their potential to reduce cardiovascular morbidity and mortality too, often through other mechanisms than these of statins. Combination trials of statins with fibrates have shown a more complete improvement of lipid profile and risk markers than each class separately. In contrast with gemfibrozil, fenofibrate does not interact significantly with the pharmacokinetics of statins, and up to now its combination with statins has been shown to have a low risk of muscular side effects or liver toxicity. The ACCORD outcome trial is exploring the possible benefits of the combination of fenofibrate with statins on morbidity and mortality of patients with atherogenic dyslipidaemia.

Monocyte-platelet complexes on CD14/CD16 monocyte subsets: relationship with ApoA-I levels. A preliminary study.

The adhesion of the monocytes to the endothelium and their extravasation into the intima are key steps in atherogenesis. Studies showed the essential role of L-selectin (CD62-L), expressed by the monocytes, and the platelets by forming complexes with monocytes. The delipided apolipoprotein (Apo) A or high-density lipoprotein (HDL) has antiinflammatory effects on monocytes and can bind platelets (monocyte-platelet complexes [MPCs]). The aim of this study was to identify a possible relationship between the MPCs, the monocyte subset, and ApoA-I/HDL serum levels in vivo. Platelet-monocyte complexes were estimated by flow cytometry in 16 volunteers. Monocyte-platelet interaction was characterized by the percentage of monocytes coexpressing the constitutive platelet marker, glycocalicin gpIb-alpha (CD42b; CD42b+monocytes in %, MPC%). Monocytes were divided into four subsets based on lipopolysaccharide receptor (CD14) and FcgammaIII receptor (CD16) expression (CD14++/CD16-, G1; CD14++/CD16+, G2; CD14+/CD16-, G3; and CD14+/CD16+, G4). HDL and ApoA-I levels were measured by routine laboratory techniques. MPC% in the different subsets were G1=8.1+/-3.4%, G2=21.2+/-14%, G3=18+/-12.6%, and G4=22.3+/-14.3% (analysis of variance: P<.001). MPC% in the entire monocyte population was negatively correlated to ApoA-I (R=-0.71, P=.001). The relationship between ApoA-I and MPC% was found mainly in the subsets G1 (R=-0.67, P=.001) and G2 (R=-0.61, P=.01). MPC% was not correlated with any other lipids or lipoprotein or high-sensitivity C-reactive protein. When whole blood was incubated with HDL/ApoA-I, no modification of platelet CD42b fluorescence was observed, indicating that there is no direct interaction between the HDL/ApoA-I and the CD42b fluorescence. Among the monocytes, the G2 subset appeared to have the highest extravasation potential. Indeed, we previously showed that those cells overexpressed CD62-L, and we observed in this work that they were coated with platelets more than the G1 cells. The G2 subset could be more directly involved in the development of atherosclerotic lesions.

Development and validation of a screening procedure for the assessment of inhibition using a recombinant enzyme.

Myeloperoxidase (MPO, E.C. 1.1.11.7) is a heme-containing enzyme that catalyses the synthesis of hypochlorous acid (HOCl) in the presence of hydrogen peroxide (H2O2) and chlorine anions. The production of HOCl is kept under strict control of neutrophils. However, in several pathological conditions, MPO is leaked in the extracellular fluid, which involves an over-production of reactive oxygen species like HOCl and promotes the damages caused by neutrophils. As a consequence, the inhibition of MPO by various agents has been investigated and a variety of molecules have been evaluated for this activity in different models. The present study aims to describe and validate a rapid screening method based on the taurine assay and using a recombinant MPO. After validation of the stock solutions used during the experiments, the amount of MPO for the completion of the reaction was measured and fixed to an optimal value. The inhibiting concentration at 50% of flufenamic acid (taken as a reference molecule) was then assessed in both a simple tube test and a microplate test and delivered similar results (1.3+/-0.2 microM vs 1.4+/-0.2 microM, P=0.2). Finally, different molecules able to inhibit MPO were evaluated in this rapid assay system providing results comparable to literature. The high throughput screening is undoubtedly a first line assessment method which affords the selection of inhibitors and permits to reduce the number of candidates for a further elucidation of the mechanism of MPO inhibition.

Conception of myeloperoxidase inhibitors derived from flufenamic acid by computational docking and structure modification.

The development of myeloperoxidase (MPO) inhibitors has been conducted using flufenamic acid as a lead compound. Computational docking of the drug and its analogs in the MPO active site was first attempted. Several molecules were then synthesized and assessed using three procedures for the measurement of their inhibiting activity: (i) the taurine assay, (ii) the accumulation of compound II, and (iii) the LDL oxidation by ELISA. Most of the synthesized molecules had an activity in the same range as flufenamic acid but none of them were able to inhibit the MPO-dependent LDL oxidation. The experiments however gave some useful indications for a rational conception of MPO inhibitors.

Sleep restriction increases white blood cells, mainly neutrophil count, in young healthy men: a pilot study.

OBJECTIVES: This study examines the effects of sleep restricted to four hours for three consecutive nights on blood parameters, known to be associated with cardiovascular risk, in young healthy men. MATERIAL AND METHODS: Eight young healthy men (age 24.5 +/- 3.3 years) were studied in the sleep restricted group. Nine young healthy men (age 24 +/- 2 years) were included in the control group and spent the days and nights in the sleep lab, while sleeping eight hours/night. One baseline night was followed by three nights of sleep restriction to four hours and by one recovery night of eight hours. Blood samplings were performed after the baseline night and after the third night of sleep restriction or without restriction for the control group. RESULTS: A significant increase in white blood cells (WBC) (5.79 +/- 1.05 vs. 6.89 +/- 1.31 10(3) cell/microl, p = 0.03), and neutrophils (3.17 +/- 0.69 vs 4.24 +/- 0.97 10(3) cell/microl, p = 0.01) was observed after the third night of sleep restriction. Other blood parameters were not affected. No significant variation was observed in the control group. CONCLUSION: Sleep restriction affected WBC count, mainly neutrophils, considered as risk factor for cardiovascular disease. Stress induced by the short term sleep restriction could be involved in this observation.

Inhibition of the myeloperoxidase chlorinating activity by non-steroidal anti-inflammatory drugs: flufenamic acid and its 5-chloro-derivative directly interact with a recombinant human myeloperoxidase to inhibit the synthesis of hypochlorous acid.

The present in vitro study was designed to assess the inhibition of the myeloperoxidase (MPO)/H(2)O(2)/Cl(-) system by several non steroidal anti-inflammatory drugs (NSAIDs) of the oxicam family and of nimesulide and to compare their effect with flufenamic acid in order to investigate their influence on the chlorinating activity of MPO as a protective mechanism during chronic inflammatory syndromes. The inhibition of the system was assessed by measurement of the taurine chlorination while the accumulation of compound II was used to investigate the mechanism of inhibition. The oxidation products of NSAIDs by the MPO/H(2)O(2)/Cl(-) system were identified and flufenamic acid and derivatives were also assessed in the inhibition of LDL oxidation in two models. Flufenamic acid (IC(50) = 1.1+/-0.3 microM) is the most efficient inhibitor of the MPO/H(2)O(2)/Cl(-) system and nimesulide (IC(50) = 2.1+/-0.3 microM) is more active than the other NSAIDs of the oxicam family (IC(50) = 8-12 microM). The accumulation of compound II revealed that flufenamic acid acts as an electron donor while the other NSAIDs are antagonists of chloride anions. The identification of the oxidation products confirms that flufenamic behaves like an electron donor and is directly oxidized in the 5-hydroxy-derivative but gives also the 5-chloro-derivative which similarly inhibits the MPO/H(2)O(2)/Cl(-) system. Flufenamic acid has the best inhibiting activity towards the MPO/H(2)O(2)/Cl(-) system. However, in models that assess the LDL oxidation, flufenamic acid and its derivatives were unable to properly inhibit MPO activity as the enzyme is adsorbed on macrostructures such as LDL molecules.

Efficacy of atorvastatin after LDL-cholesterol-based dose selection in high risk dyslipidaemic patients: results of the target dose study.

BACKGROUND: Hypercholesterolaemia is one of the major risk factors for the development of coronary heart disease (CHD). European guidelines emphasize the importance of reducing low-density lipoprotein cholesterol (LDL-C) levels below 115 mg/dL (3.0 mmol/L) in patients with high CHD risk. OBJECTIVE: The present study evaluates whether selection of the atorvastatin starting dose based on baseline LDL-C levels and previous statin treatment status would result in an achievement of LDL-C targets without the need for up-titration. METHODS: A multicentre, prospective, open-label study conducted in Belgium. Patients were at high risk defined as either a history of CHD, another atherosclerotic disease, diabetes mellitus Type 2 or an estimated 10-year CHD risk > 20%. The primary endpoint was the proportion of patients achieving the LDL-C goal after 12 weeks of treatment. RESULTS: Overall, 96.4% of the 195 statin-naïve patients reached the LDL-C target after 12 weeks of treatment. The majority of the patients (95.4%) already reached LDL-C control at Week 6. Mean (SD) LDL-C levels decreased from 159 (25) mg/dL[(4.1 (0.6) mmol/L] to 86 (14) mg/dL [2.2 (0.4) mmol/L] after 12 weeks of treatment. Only 4.6% of the patients needed an up-titration at Week 6. CONCLUSIONS: Taken together, the results demonstrate that LDL-C based dose selection of atorvastatin is highly efficacious for rapid achievement of target LDL-C levels with a low need for up-titration. Application of this flexible first dosing strategy in general practice will, based on available evidence, increase adherence to atorvastatin treatment in patients with high CHD risk.

Presence of LDL modified by myeloperoxidase in the penis in patients with vascular erectile dysfunction: a preliminary study.

OBJECTIVE: Erectile dysfunction (ED) is a major vascular disorder. Atherosclerosis is closely related to lipoprotein metabolism and especially, oxidative modifications of low-density lipoproteins (LDLs), which are involved in early development of the atherosclerotic lesions. Current major questions include how LDLs are oxidised (OxLDL) in vivo. Myeloperoxidase (MPO) is an enzyme present in the azurophile granules of neutrophils and monocytes that can contribute to LDL oxidation in the presence of H(2)O(2). We have developed a new monoclonal antibody against LDL modified by MPO (Mox-LDL) and have used it on penile biopsies from patients operated on for penile implant. METHODS: Seven patients with vascular ED and one impotent patient after radical prostatectomy (RP) underwent biopsy of the cavernous body during penile implant procedures. An immunohistochemical study with a monoclonal antibody against Mox-LDL and an antibody against apoprotein B (ApoB), the protein moiety of LDL, to confirm the presence of LDL was performed. RESULTS: The staining was positive for Mox-LDL and ApoB and was present between the endothelial cells of the sinusoid spaces and the smooth muscle cells in the seven patients with vascular ED. The patient with RP was negative for Mox-LDL. DISCUSSION: Because it is known that modified LDL could decrease nitric oxide production, Mox-LDL could be one of the agents responsible for ED. Further studies are needed to confirm this hypothesis.