David Busseuil

Increased superoxide anion production is associated with early atherosclerosis and cardiovascular dysfunctions in a rabbit model

ObjectiveHypercholesterolemia (HC) has been associated with impairment of vascular and myocardial functions. As HC could generate an alteration in the oxidative status, we studied the effects of a 1-month cholesterol diet on cardiovascular oxidative stress.Methods and ResultsNew Zealand rabbits received cholesterol (1%) or normal chow for 1xa0month. At 30xa0days, superoxide anion levels, assessed by ESR spectroscopy, NAD(P)H oxidase (NOX) activity, and dihydroethidium (DHE) staining of aortas were higher in the cholesterol-fed (CF) group compared with control (respectively, 4.0 ± 0.6xa0Arbitraryxa0Units/mg (AU/mg) vs. 2.6 ± 0.3, p < 0.05; 4231 ± 433 vs. 2931 ± 373xa0AU/mg, p < 0.05; 21.4 ± 1.2 vs. 12.9 ± 1.7% fluorescence/mm2, p < 0.001). NOX gp91phox and p67phox expression in the aortas were higher in the CF group vs. control (1.5 ± 0.2 vs. 0.5 ± 0.2, p < 0.001; 0.9 ± 0.2 vs. 0.3 ± 0.2, p < 0.05). The endothelium-dependent relaxation evaluated on the iliac arteries was higher in control than in the CF group (64.8 ± 10.1 vs. 13.1 ± 3.70%, p < 0.001). The cardiac diastolic pressure estimated on isolated hearts was higher in the CF group than in control (21.1 ± 4.1 vs. 10.3 ± 1.4xa0mmHg, p < 0.05) after 60xa0min of ischemia.ConclusionsHypercholesterolemia induced increased levels of superoxide in the aortas and a higher expression of NOX subunits, associated with altered vasorelaxation. The increased diastolic pressure observed in hearts, consistent with a post-ischemic contractile dysfunction might be mediated by the production of superoxide.

Modification of the rat aortic wall during ageing; possible relation with decrease of peptidergic innervation.

Structural changes of the male rat aorta were followed from birth to old age in male and female rats. In males, the vessel media width and area progressively increase concomitantly with a decrease of nuclei density during ageing, suggesting an hypertrophy of the smooth muscle cells. These correlations were however not evidenced in females. TUNEL-positive cells were found in media of 4 and 6 months in both sexes, mainly on the luminal side and in the adventitia. When biochemical markers were investigated with immunohistochemistry, media was uniformly stained by the anti-vimentin and anti-α-smooth actin at all stages investigated. On the contrary, the surface of media stained with anti-desmin decreased during ageing, especially on the luminal side. As observed with electron microscopy, with ageing the endothelium is replaced by small cells with pseudopodia adhering to the vestigial elastic lamina and infiltrating into the extracellular matrix left after the disappearance of smooth muscle cells. In addition, in the older rats (25–29 months) the elastic laminae are completely disorganised. Hypertrophy of the smooth muscle cells was confirmed by this approach. In parallel to this study, perivascular peptidergic innervation was stained with antibodies against calcitonin gene-related peptide (CGRP), substance P (SP), neuropeptide Y (NPY), and vasoactive intestinal polypeptide (VIP) at different ages during the whole life of rats. These peptides are present in stages younger than 6 months, then gradually disappear. In one year animals and older, the peptidergic innervation has totally disappeared. We discuss the possible role of peptidergic innervation in the control of the vessel wall cellular stability during ageing.

Late neointimal tissue growth behind the stent after intravascular γ-radiation

Abstract Purpose To determine the nature of the changes of the vascular wall after intravascular brachytherapy in stented arteries leading to incomplete stent apposition. Methods and materials Stents were implanted in the infrarenal aortas of rabbits, and γ-intravascular brachytherapy (18 Gy) or a sham radiation procedure was immediately implemented. The arteries were harvested at 6 months for histologic analyses. Results The external elastic lamina area, as well as the vascular wall area behind the stent, were significantly greater in irradiated vs. control arteries (8.94 ± 0.68 mm 2 vs. 6.87 ± 0.40 mm 2 [ p 2 vs. 0.72 ± 0.07 mm 2 [ p p Conclusion Our study revealed the presence of a neointimal layer specifically located behind the stent, which represented the result of an unhealed fibrin-rich tissue growth process 6 months after intravascular brachytherapy.

Intravascular radiation and stenting: absence of efficacy on intimal proliferation in a rabbit model.

David Busseuil1, Marianne Zeller 2, Yves Cottin2, Philippe Allouch2, Philippe Maingon3, Isabelle Barillot3, Suzanne Naudy3, Laurent Arnould4, Gabrielle Michalowicz5, Maryvonne Moisant6, Jean-Claude Horiot3, Jean-Eric Wolf2, and Luc Rochette1 1LPPCE, Faculty of Medicine, University of Burgundy; 2Cardiology Department, University, Hospital, Dijon; 3Radiotherapy Department, CGFL, Dijon; 4Pathology Department, CGFL, Dijon; 5Genetics Department, University Hospital, Grenoble, France; Histology Department, Faculty of Medicine, University of Burgundy

Combining sirolimus-eluting stents and external irradiation in cholesterol-fed rabbits increased incomplete stent apposition and decreased re-endothelialization.

Restenosis after the implantation of a drug-eluting stent or after vascular irradiation therapy shares similar physiopathological mechanisms. No experimental data are currently available on vascular wall behavior after external irradiation on arteries stented with sirolimus-eluting stents (SES). Ten New Zealand white rabbits received a 0.5% cholesterol-enriched chow for 1 month. Bilateral iliac artery stent implantation was then performed with an SES (Cypher; Cordis Corp). The animals were randomized into either an irradiated group (I, 2 Gy external x-ray irradiation, n = 5) or a control group (C, n = 5). The cholesterol-enriched chow was continued for 1 additional month after stent implantation. The stented arteries were harvested for histological analyses. The number and the percentage of incompletely apposed stents struts (IASS) were significantly higher in irradiated versus control group (3.05 ± 0.46 vs. 1.57 ± 0.27 IASS, P < 0.01, and 28.44% ± 3.97% vs. 15.2% ± 2.46% of IASS, P < 0.01, respectively). The mean neointimal thickness behind the IASS was also higher in the irradiated group (I: 28.3 ± 2.5 μm vs. C: 18.2 ± 2.3 μm, P < 0.01). Re-endothelialization was lower in irradiated group (I: 44.6% ± 17.5% vs. C: 75.2% ± 5.7%, P < 0.01). The present study revealed that low-dose external irradiation increased incomplete stent apposition and reduced re-endothelialization of SES. These results underscore the potential deleterious cumulative side effects of these 2 procedures to prevent restenosis.

A treatment with rosuvastatin induced a reduction of arterial pressure and a decrease of oxidative stress in spontaneously hypertensive rats

The aim of this study was to appreciate consequences of rosuvastatin administration on hemodynamic function, vascular oxidative stress and ischemia/reperfusion disorders in normotensive and hypertensive rats. At 10 weeks of age, spontaneously hypertensive rats (SHR, n=20) and normotensive Wistar Kyoto male rats (WKY, n=20) were divided into four groups and given, either vehicle or 10 mg/kg/day of rosuvastatin by gavage for 3 weeks. Systolic blood pressure was assessed every week. At the end of these treatments, vascular NADPH oxidase activity was evaluated by chemiluminescence (lucigenin 0.5 microM). Hearts were isolated and perfused according to the Langendorff method and were subjected to 30 min of global ischemia. Reactive oxygen species (ROS) produced during reperfusion were quantified by electron spin resonance (ESR) spectroscopy using a spin probe (CP-H, 1 mM). After one week of treatment, rosuvastatin reduced the arterial pressure in SHR rats (180.3 +/- 2.1, SHR vs 169.7 +/- 2.3 mmHg, SHR+rosuvastatin; p < 0.01), without lowering plasma cholesterol levels; these effects were not observed in WKY. NADPH activity was 25% higher in control SHR rat aortas compared to control WKY, and was reduced by rosuvastatin in SHR rats. In isolated rat hearts subjected to ischemia/reperfusion sequences, there was a deterioration in functional parameters in control SHR compared to control WKY hearts. Rosuvastatin decreased post-ischemic contracture in WKY hearts by 50% (41.5 +/- 7.5, WKY control vs 18.4 +/- 4.6 mmHg, WKY+rosuvastatin; p < 0.01) and increased left ventricular developed pressure. This beneficial effect was accompanied by a decrease in ROS detected by ESR during reperfusion (312.5 +/- 45.3, WKY control; vs 219.3 +/- 22.9 AUC/mL, WKY+rosuvastatin; p < 0.05). In conclusion, these results are in accordance with the hypothesis that oxidative stress plays a crucial role in the pathogenesis of cardiovascular diseases including hypertension, and demonstrate the beneficial effects of rosuvastatin.