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Myocardial infarction and stroke are frequent after surgical procedures and consume a considerable amount of benefit of surgical therapy. Perioperative stress, induced by surgery, is composed of hemodynamic and inflammatory reactions. The effects of perioperative stress on atherosclerotic plaques are ill-defined. Murine models to investigate the influence of perioperative stress on plaque stability and rupture are not available. We developed a model to investigate the influence of perioperative stress on plaque growth and stability by exposing apolipoprotein-E-deficient mice, fed a high cholesterol diet for 7 weeks, to a double hit consisting of 30 min of laparotomy combined with a substantial blood loss (approximately 20% of total blood volume; 400 µl). The innominate artery was harvested 72 h after the intervention. Control groups were sham and baseline controls. Interleukin-6 (IL-6) and serum amyloid A (SAA) plasma levels were determined. Plaque load, vascular smooth muscle cell (VSMC) and macrophage content were quantified. Plaque stability was assessed using the Stary score and frequency of signs of plaque rupture were assessed. High-dose atorvastatin (80 mg/kg body weight/day) was administered for 6 days starting 3 days prior to the double hit. A single dose of an IL-6-neutralizing antibody or the fusion protein gp130-Fc selectively targeting IL-6 trans-signaling was subcutaneously injected. IL-6 plasma levels increased, peaking at 6 h after the intervention. SAA levels peaked at 24 h (n=4, P<0.01). Plaque volume increased significantly with the double hit compared to sham (n=8, P<0.01). More plaques were scored as complex or bearing signs of rupture after the double hit compared to sham (n=5-8, P<0.05). Relative VSMC and macrophage content remained unchanged. IL-6-inhibition or atorvastatin, but not blocking of IL-6 trans-signaling, significantly decreased plaque volume and complexity (n=8, P<0.01). Using this model, researchers will be able to further investigate the pathophysiology of perioperative plaque stability, which can result in myocardial infarction, and, additionally, to test potential protective strategies.

The objective of this study was to determine if spontaneous breast cancer lesions can be detected by fluorescence reflectance imaging (FRI) and fluorescence mediated tomography (FMT) using protease-sensing optical probes.

Thrombomodulin (TM) is a vascular endothelial cell (EC) receptor that is a cofactor for thrombin-mediated activation of the anticoagulant protein C. The extracellular NH2-terminal domain of TM has homology to C-type lectins that are involved in immune regulation. Using transgenic mice that lack this structure (TMLeD/LeD), we show that the lectin-like domain of TM interferes with polymorphonuclear leukocyte (PMN) adhesion to ECs by intercellular adhesion molecule 1–dependent and –independent pathways through the suppression of extracellular signal–regulated kinase (ERK)1/2 activation. TMLeD/LeD mice have reduced survival after endotoxin exposure, accumulate more PMNs in their lungs, and develop larger infarcts after myocardial ischemia/reperfusion. The recombinant lectin-like domain of TM suppresses PMN adhesion to ECs, diminishes cytokine-induced increase in nuclear factor κB and activation of ERK1/2, and rescues ECs from serum starvation, findings that may explain why plasma levels of soluble TM are inversely correlated with cardiovascular disease. These data suggest that TM has antiinflammatory properties in addition to its role in coagulation and fibrinolysis.

Platelets are thought to play a causal role during atherogenesis. Platelet-endothelial interactions in vivo and their molecular mechanisms under shear are, however, incompletely characterized. Here, an in vivo platelet homing assay was used in hypercholesterolemic rabbits to track platelet adhesion to plaque predilection sites. The role of platelet versus aortic endothelial cell (EC) activation was studied in an ex vivo flow chamber. Pathways of human platelet immobilization were detailed during in vitro perfusion studies. In rabbits, a 0.125% cholesterol diet induced no lesions within 3 months, but fatty streaks were found after 12 months. ECs at segmental arteries of 3- month rabbits expressed more von Willebrand factor (VWF) and recruited 5-fold more platelets than controls (P < .05, n = 5 and 4, respectively). The 3-month ostia had an increased likelihood to recruit platelets compared to control ostia (56% versus 18%, P < .0001, n = 89 and 63, respectively). Ex vivo, the adhesion of 3-month platelets to 3-month aortas was 8.4-fold increased compared to control studies (P < .01, n = 7 and 5, respectively). In vitro, endothelial VWF–platelet glycoprotein (GP) Ib and platelet P-selectin– endothelial P-selectin glycoprotein ligand 1 interactions accounted in combination for 83% of translocation and 90% of adhesion (P < .01, n = 4) of activated human platelets to activated human ECs. Platelet tethering was mainly mediated by platelet GPIbα, whereas platelet GPIIb/IIIa contributed 20% to arrest (P < .05). In conclusion, hypercholesterolemia primes platelets for recruitment via VWF, GPIbα, and P-selectin to lesion-prone sites, before lesions are detectable.

Platelets are thought to play a causal role during atherogenesis. Platelet-endothelial interactions in vivo and their molecular mechanisms under shear are, however, incompletely characterized. Here, an in vivo platelet homing assay was used in hypercholesterolemic rabbits to track platelet adhesion to plaque predilection sites. The role of platelet versus aortic endothelial cell (EC) activation was studied in an ex vivo flow chamber. Pathways of human platelet immobilization were detailed during in vitro perfusion studies. In rabbits, a 0.125% cholesterol diet induced no lesions within 3 months, but fatty streaks were found after 12 months. ECs at segmental arteries of 3- month rabbits expressed more von Willebrand factor (VWF) and recruited 5-fold more platelets than controls (P< .05, n = 5 and 4, respectively). The 3-month ostia had an increased likelihood to recruit platelets compared to control ostia (56% versus 18%, P< .0001, n = 89 and 63, respectively). Ex vivo, the adhesion of 3-month platelets to 3-month aortas was 8.4-fold increased compared to control studies (P< .01, n = 7 and 5, respectively). In vitro,endothelial VWF–platelet glycoprotein (GP) Ib and platelet P-selectin– endothelial P-selectin glycoprotein ligand 1 interactions accounted in combination for 83% of translocation and 90% of adhesion (P< .01, n = 4) of activated human platelets to activated human ECs. Platelet tethering was mainly mediated by platelet GPIbα, whereas platelet GPIIb/IIIa contributed 20% to arrest (P< .05). In conclusion, hypercholesterolemia primes platelets for recruitment via VWF, GPIbα, and P-selectin to lesion-prone sites, before lesions are detectable.

This review presents a brief overview about the role of regional anaesthesia in patients at risk for myocardial ischemia andor infarction after cardiac and noncardiac surgical procedures. It includes pathophysiological insights in the problems of plaque rupture and the possible interactions by the use of regional anaesthesia. Special emphasis is put on the subject of thoracic epidural anaesthesia with newer studies showing improvement in relief of angina and improvement of global systolic and diastolic function in patients with coronary artery disease.

Macrophage infiltration into the subendothelial space at lesion prone sites is the primary event in atherogenesis. Inhibition of macrophage homing might therefore prevent atherosclerosis. Since HDL levels are inversely correlated with cardiovascular risk, their effect on macrophage homing was assessed in apoE‐deficient (apoE−/−) mice. Overexpression of human apolipoprotein AI in apoE−/−mice increased HDL levels 3‐fold and reduced macrophage accumulation in an established assay of leukocyte homing to aortic root endothelium 3.2‐fold (P< 0.005). This was due to reduced in vivoβVLDL oxidation, reduced βVLDL triggered endothelial cytosolic Ca2+signaling through PAF‐like bioactivity, lower ICAM‐1 and VCAM‐1 expression, and diminished ex vivoleukocyte adhesion. Adenoviral gene transfer of human PAF‐acetylhydrolase (PAF‐AH) in apoE−/−mice increased PAF‐AH activity 1.5‐fold (P<0.001), reduced β VLDL‐induced ex vivomacrophage adhesion 3.5‐fold (P<0.01), and reduced in vivomacrophage homing 2.6‐fold (P<0.02). These inhibitory effects were observed in the absence of increased HDL cholesterol levels. In conclusion, HDL reduces macrophage homing to endothelium by reducing oxidative stress via its associated PAF‐AH activity. This protective mechanism is independent of the function of HDL as cholesterol acceptor. Modulation of lipoprotein oxidation by PAF‐AH may prevent leukocyte recruitment to the vessel wall, a key feature in atherogenesis.—Theilmeier, G., De Geest, B., Van Veldhoven, P. P., Stengel, D., Michiels, C., Lox, M., Landeloos, M., Chapman, M. J., Ninio, E., Collen, D., Himpens, B., Holvoet, P. HDL‐associated PAF‐AH reduces endothelial adhesiveness in apoE−/−mice. FASEB J.14, 2032–2039 (2000)

Circulating complexes of leukocytes and activated platelets are markers for atherosclerosis, but their interaction with the arterial endothelial lining has not been studied. Therefore, the effect of activated platelets on rolling and adhesion of labeled human THP-1 monocytoid cells to human umbilical vein endothelial cell (HUVEC) monolayers was studied by epifluorescence microscopy in a parallel plate flow chamber. In the absence of activated platelets, THP-1 rolling on resting HUVEC was negligible at shear rates greater than 300 s−1. Activation of HUVEC with 100 nmol/L phorbol myristate acetate (PMA) increased THP-1 cell adhesion at shear rates less than 400 s−1. Therefore, a shear rate of 400 s−1 was identified as a threshold for THP-1 adhesion. THP-1 rolling on activated HUVEC was reduced by 64% after L-selectin inhibition but was not affected by P-selectin inhibition. The addition of 1 to 50 thrombin receptor-activating peptide (TRAP)-activated platelets per THP-1 cell enhanced interactions between THP-1 cells and HUVEC, resulting in a steep bell-shaped dose-response curve, with a peak of 10 ± 3 rolling cells/50 seconds at 3 platelets per THP-1 cell (P < .01v control) with a concomitant 2- to 3-fold increase of firmly adhering cells (P < .01 v control). In reconstituted blood, low numbers of activated platelets had the same effect on THP-1 rolling and adhesion. P-selectin inhibition reduced platelet/THP-1 cell interaction in suspension and deposition of the complexes on the endothelial monolayer. Inhibition of both P- and L-selectin reduced THP-1/HUVEC interactions to 14% (P < .01, n = 4). Sialidase digestion and removal of terminal sialic acid residues from HUVEC or THP-1 cells but not from platelets abolished the platelet mediated augmentation of THP-1 cell adhesion. Thus, THP-1 rolling on HUVEC is shear-dependent and largely mediated by L-selectin. P-selectin expressed on activated platelets increases monocytoid cell adhesion to endothelial cells at shear rates found in coronary arteries through interactions with both endothelial and monocytoid cells and may facilitate macrophage accumulation in the vessel wall.

Objectives. The present study was designed to test the hypothesis that long-term dietary supplementation with the nitric oxide precursor l-arginine would enhance vascular or platelet-derived nitric oxide activity, or both, and thereby inhibit platelet reactivity in hypercholesterolemic humans.

Carbon monoxide is hypothesized to be produced by the enzyme heme oxygenase predominantly in liver and spleen, bound to hemoglobin, and excreted by the lungs. Thus, venous carboxyhemoglobin is expected to be higher or equal to arterial carboxyhemoglobin. Unspecific inflammatory stimuli have been shown to induce heme oxygenase in lung tissue possibly leading to pulmonary carbon monoxide production. Arterial and central venous carboxyhemoglobin levels were measured in critically ill patients on the third day of ICU stay (n = 59) as well as in otherwise healthy humans prior to orthopedic surgery (n = 29). Arterial and central venous carboxyhemoglobin were higher in ICU patients than in healthy humans, respectively. In both groups, arterial carboxyhemoglobin was significantly higher than central venous carboxyhemoglobin. The arterio-venous carboxyhemoglobin differences were similar in both groups. The data suggest (a) increased CO-generation in critical illness and (b) pulmonary CO-production in healthy and critically ill humans.

Enhanced interaction of mononuclear cells with the endothelium is the first observable event in the development of atherosclerosis. Hypercholesterolemia reduces vascular nitric oxide activity. This dysfunction may promote endothelial monocyte interaction, as NO is a potent inhibitor of adhesion. We have previously shown that dietary L-arginine (Arg) supplementation in hypercholesterolemic rabbits restores NO activity and inhibits monocyte-endothelial cell interaction, in association with a reduction in atherogenesis. Accordingly we developed a functional binding assay to assess the adhesiveness of human mononuclear cells, so as to determine the effects of hypercholesterolemia and L-arginine therapy. We found a 50% increase in adhesion of mononuclear cells (MNC) from hypercholesterolemic (HC) subjects to cultured endothelial cells ex vivocompared to a normocholesterolemic control population (p&lt;0.0001, n = 20). Increased MNC adhesion was reversed to normal levels by preincubation of the MNC suspension with 10-5M sodium nitroprusside (164.4±8.7% vs 97.5±6.9%, P &lt; 0.0005, n = 7), while L-nitroarginine and Arg did not have an effect in vitro. In a double-blinded placebo-controlled study, oral Arg (8.4 g/day) was administered to 7 HC subjects. Over a course of two weeks, this treatment abolished the increased adhesion (158.5±10.9% vs 103.5±4.9% vs 100±5.2%, HCvs Arg vs Control. p&lt;0.005), while MNC adhesion remained significantly elevated in placebo-treated subjects.

We have shown that vascular NO activity is reduced in hypercholesterolemic animals, and that this abnormality can be reversed by dietary L-arginine (Arg) supplementation. A sustained improvement in vascular NO activity is associated with a reduction in platelet reactivity and elevation of platelet cGMP that is reversed by NO synthase inhibition. This study tested the hypothesis that chronic Arg supplementation would inhibit platelet reactivity in hypercholesterolemic humans. Venous blood was collected from normal (NC; n=11) and hypercholesterolemic (HC; n=22) volunteers for isolation of plateletrich plasma and aggregometry. Half the HC group received Arg (8.4 g/d) for 2 weeks; aggregometry was performed using collagen (5μg/ml) before and after 2 wks of treatment, and after a 2-wk washout.