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Objective: Atherosclerosis, a chronic inflammatory disease, arises from metabolic disorders and is driven by inappropriate recruitment and proliferation of monocytes / macrophages and vascular smooth-muscle-cells. The receptor for the urokinase-type plasminogen activator (uPAR, Plaur) regulates the proteolytic activation of plasminogen. It is also a coactivator of integrins and facilitates leukocyte-endothelial interactions and vascular smooth-muscle-cell migration. The role of uPAR in atherogenesis remains elusive. Methods and Results: We generated C57Bl6/J low-density lipoprotein receptor (LDL) and uPAR double knockout (uPAR-/-/LDLR-/-) mice to test the role of uPAR in two distinct atherosclerosis models. In LDLR-/- mice, hepatic overexpression following hydrodynamic transfection of soluble uPAR that competes with endogenous membrane-bound uPAR was performed as an interventional strategy. Aortic root atherosclerotic lesions induced by feeding a high-fat diet were smaller and comprised less macrophages and vascular smooth-muscle-cells in double knockout mice and animals overexpressing soluble uPAR when compared to controls. In contrast, lesion size, lipid-, macrophage-, and vascular smooth muscle cell content of guide-wire-induced intima lesions in the carotid artery were not affected by uPAR deficiency. Adhesion of uPAR-/--macrophages to TNFα-stimulated endothelial cells was decreased in vitro accompanied by reduced VCAM-1 expression on primary endothelial cells. Hepatic overexpression of soluble full-length murine uPAR in LDLR-/- mice led to a reduction of diet-induced atherosclerotic lesion formation and monocyte recruitment into plaques. Ex vivo incubation with soluble uPAR protein also inhibited adhesion of macrophages to TNFα-stimulated endothelial cells in vitro. Conclusion: uPAR-deficiency as well as competitive soluble uPAR reduced diet-promoted but not guide-wire induced atherosclerotic lesions in mice by preventing monocyte recruitment and vascular smooth-muscle-cell infiltration. Soluble uPAR may represent a therapeutic tool for the modulation of hyperlipidemia-associated atherosclerotic lesion formation. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: Occupational exposure to nitrous oxide (N2O) and/or halogenated hydrocarbons has been suggested to induce damage of genetic material, but the underlying mechanisms remain obscure. This study investigated the role of oxidative processes in the genotoxicity associated with exposure to waste anaesthetic gases. Methods: The study was performed in 36 female nurses and in 36 unexposed female health care workers matched for age and employment duration. Genotoxic effects were examined by Comet test modification employing formamidopyrimidine glycosylase (FPG) that allows assessment of oxidative DNA damage. Reactive oxygen species (ROS) in leukocytes were investigated by fluorescence spectroscopy with 2′,7′-dichlorofluorescin diacetate. Oxidative stress markers including 8-iso-prostaglandin F2α (8-iso-PGF2α), thiobarbituric acid-reacive substances (TBARS), α-tocopherol, and glutathione peroxidise (GPX) activity were measured immuno- or colorimetrically. N2O, sevoflurane and isoflurane were monitored by gas chromatography and mass spectrometry. Results: The study documents for the first time the positive correlation between the oxidative DNA damage and the N2O levels in the ambient air. By contrast, no association was observed between genotoxic effects and sevoflurane or isoflurane. In addition, ROS generation and plasma and urine concentrations of TBARS and 8-iso-PGF2α, respectively, were elevated, while GPX activity was reduced in nurses exposed to waste anaesthetic gases. Path analysis pointed to a causal relationship between N2O exposure, oxidative stress and DNA damage. Conclusion: Occupational exposure to N2O is associated with increased oxidative DNA damage and the level of exposure plays a critical role in this regard. Increased oxidative stress may represent a mechanistic link between chronic N2O exposure and genotoxicity. [Copyright &y& Elsevier]

Abstract: Objectives: Oxidative stress in plasma may be promoted by plasma thiols such as homocysteine. However, other thiols such as glutathione may also exert antioxidant effects in vitro and in vivo. To further investigate whether plasma thiols act as prooxidants or antioxidants, we compared plasma oxidative status in patients with coronary heart disease (CHD) and in subjects occupationally exposed to carbon disulfide (CS2). Methods: Fifty-five subjects chronically exposed to CS2, 53 CHD patients, and 52 healthy controls were examined. To assess plasma oxidative status, concentrations of thiobarbituric reactive substances (TBARS) and total antioxidative capacity (TAC), as well as ferritin and ceruloplasmin were determined. Antioxidative reserve was assessed by the determination of vitamine E, uric acid, superoxide dismutase, catalase, and glutathion peroxidase. In addition, protein and non-protein plasma thiol levels were measured. Results: Patients in both groups had increased levels of plasma thiols as compared to controls: CS2-exposed subjects presented with increased levels of thiols associated with plasma proteins, whereas CHD patients presented with elevated total homocysteine and cysteine levels. TBARS were significantly increased and TAC was significantly decreased both in CS2-exposed subjects and in CHD patients. In addition decreased activity of glutathione peroxidase, an antioxidative enzyme inhibited by thiol-containing compounds, was noted in both groups. Conclusion: These results demonstrate that regardless of their metabolic origin increased thiols are associated with increased oxidative stress in plasma. [Copyright &y& Elsevier]

Abstract: Low density lipoproteins (LDL) inhibit the Na+/H+ antiport and thereby sensitize platelet towards agonist. However, mechanisms underlying the suppressing effect of LDL on Na+/H+ exchange are unclear. We here show that the lowering of intracellular pH and the suppression of the sodium propionate-induced Na+/H+ exchange in the presence of LDL are abolished by SKF86002, a selective inhibitor of p38MAP kinase (p38MAPK). The inhibitory effect of LDL on Na+/H+ exchange was mimicked by H2O2, which directly activates p38MAPK. Exposure of platelets to LDL or H2O2 led to phosphorylation of p38MAPK, its upstream regulator MAP kinase kinase 3/6 (MKK 3/6), and its downstream target heat shock protein 27 (HSP27), and this effect was abrogated in SKF86002-pretreated platelets. In addition, both LDL and H2O2 produced the SKF86002-sensitive phosphorylation of an oligopeptide encompassing p38MAPK phosphorylation sequence derived from NHE-1, a major Na+/H+ exchanger in platelets. We further show that the sensitizing effects of LDL on the thrombin-induced platelet activation, as reflected by aggregation and granule secretion, are abolished in cells pretreated with SKF86002. We conclude that activation of p38MAPK is required for the inhibitory effect of LDL on Na+/H+ antiport and thereby for LDL-dependent sensitization in human platelets. [Copyright &y& Elsevier]

HDL is a major atheroprotective factor, but the mechanisms underlying this effect are still obscure. HDL binding to scavenger receptor-BI has been shown to activate eNOS, although the responsible HDL entities and signaling pathways have remained enigmatic. Here we show that HDL stimulates NO release in human endothelial cells and induces vasodilation in isolated aortae via intracellular Ca2+ mobilization and Akt-mediated eNOS phosphorylation. The vasoactive effects of HDL could be mimicked by three lysophospholipids present in HDL: sphingosylphos-phorylcholine (SPC), sphingosine-1-phosphate (S1P), and lysosulfatide (LSF). All three elevated intracellular Ca2+ concentration and activated Akt and eNOS, which resulted in NO release and vasodilation. Deficiency of the lysophospholipid receptor S1P3 (also known as LPB3 and EDG3) abolished the vasodilatory effects of SPC, S1P, and LSF and reduced the effect of HDL by approximately 60%. In endothelial cells from S1P3-deficient mice, Akt phosphorylation and Ca 2+ increase in response to HDL and lysophospholipids were severely reduced. In vivo, intraarterial administration of HDL or lysophospholipids lowered mean arterial blood pressure in rats. In conclusion, we identify HDL as a carrier of bioactive lysophospholipids that regulate vascular tone via S1P3-mediated NO release. This mechanism may contribute to the vasoactive effect of HDL and represent a novel aspect of its antiatherogenic function. [ABSTRACT FROM AUTHOR]

Objective: The nuclear enzyme Poly(ADP-Ribose)-Polymerase (PARP) has been hypothesized as playing a major role in various forms of inflammation. PARP activation is induced by DNA strand breakage and can result in intracellular energy depletion and, ultimately, cell death. Further, it is thought to influence cardiovascular function and organ failure in endotoxemia. Here, we investigated the effect of the PARP inhibitor nicotinamide on cardiovascular and liver function in healthy and chronically endotoxemic sheep.Design: Prospective controlled trial.Setting: University research laboratory.Subjects: 12 female adult sheep.Interventions: Six healthy sheep, instrumented for chronic study, received nicotinamide intravenously as a bolus of 40 mg/kg followed by a continuous infusion of 10 mg.kg(-1).h(-1); six animals received the vehicle. One hour after bolus application, a continuous infusion of endotoxin ( Salmonella typhosa, 10 ng.kg(-1).min(-1)) was started. Hemodynamic parameters were determined before and during endotoxemia.Measurements and Results: Treatment with nicotinamide resulted in a significantly higher systemic vascular resistance index and lower cardiac index in endotoxemic animals, but not in controls. It also attenuated endotoxin-induced increase in gamma-glutamyl transferase.Conclusions: The PARP inhibitor nicotinamide attenuates impairment of cardiovascular function during endotoxemia. In addition, PARP activation may be involved in endotoxin-induced liver injury. [ABSTRACT FROM AUTHOR]

There is considerable epidemiological evidence that workers exposed to carbon disulfide (CS2) develop premature atherosclerosis leading to increased rates of coronary heart disease (CHD), but mechanisms underlying this association remain obscure. The present study documents that occupational exposure to CS2 modifies the oxidative status of plasma, which is a major determinant of the susceptibility to atherosclerosis. Concentrations of thiobarbituric reactive substances (TBARS), which reflect lipid peroxidation processes in plasma, were determined in 29 men who were exposed to CS2 for more than 20 years, in 24 patients with peripheral atherosclerosis, and in 30 unexposed, healthy control subjects. TBARS concentrations were significantly increased both in CS2-exposed subjects and in patients with peripheral atherosclerosis. Subjects in both groups presented also with decreased levels of plasma α-tocopherol, a major plasma antioxidant. In addition, decreased activities of two enzymatic antioxidants, glutathion peroxidase and catalase, were noted both in CS2-exposed subjects and patients with peripheral atherosclerosis. Finally, LDL isolated from both groups showed increased susceptibility to transition metal-induced oxidation in vitro. It is concluded, that occupational exposure to CS2 produces oxidative stress in plasma. This may favor the development of atherosclerosis and increase the incidence of CHD in workers exposed to CS2. [ABSTRACT FROM AUTHOR]