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Bernard I Levy

Publications and source records attributed to Bernard I Levy.

5 recordsLinked to original sources
PubMed2002

Endothelial nitric oxide synthase lies downstream from angiotensin II-induced angiogenesis in ischemic hindlimb.

We assessed the role of angiotensin (Ang) II in ischemia-induced angiogenesis and analyzed the molecular pathways involved in such an effect. Ischemia was produced by unilateral artery femoral occlusion in control, in valsartan-treated (Ang II receptor type I antagonist, 20 mg/kg per day), in Ang II-treated (5 ng/kg per min), and in Ang II and valsartan-treated rats. After 28 days, angiogenesis was assessed by microangiography and capillary density measurement in hindlimbs. The ischemic/nonischemic leg ratio for angiographic score and capillary number increased by 2.6- and 2-fold, respectively, in Ang II-treated rats compared with controls (P<0.01). This was associated with an increase in vascular endothelial growth factor (VEGF; 1.6-fold) and endothelial NO synthase (eNOS; 1.8-fold) protein content within the ischemic leg, assessed by Western blot. Angiotensin type 1 receptor blockade and administration of VEGF neutralizing antibody (2.5 microg IP, twice a week) in Ang II-treated rats completely prevented such Ang II angiogenic effects. The key role of eNOS was then emphasized by using mice deficient in gene encoding for eNOS. In wild-type mice, Ang II (0.3 mg/kg per min) treatment increased by 1.7- and 1.6-fold the ischemic/nonischemic leg for angiographic score and blood perfusion (assessed by laser Doppler perfusion imaging) ratios, respectively (P<0.01). Conversely, no significant changes were observed in Ang II-treated mice deficient in gene encoding for eNOS. Subhypertensive dose of Ang II enhanced angiogenesis associated with tissue ischemia through angiotensin type 1 receptor activation that involved the VEGF/eNOS-dependent pathway.

Angiotensin II↗
PubMed2002

Genetic determinants of vascular reactivity.

Blood pressure is controlled by a complex combination of processes that influence cardiac output and peripheral vascular resistance. Multiple genes potentially influence each parameter involved in the control of blood pressure, and individuals with the same blood pressor level do not necessarily have the same genotype at relevant loci, nor do individuals with the same genotype at particular loci necessarily have the same blood pressure. Nevertheless, pharmacogenetic studies of vascular reactivity will certainly allow the analysis of the mechanisms affected by genes, and lead to a better understanding of the epidemiologic observations seen in large groups of patients. Polymorphisms in the genes of the renin-angiotensin system allow definition of the "genetic profile" associated with a higher risk of cardiovascular disease, and can also be linked to significant changes in vascular reactivity in arteries isolated from patients carrying the polymorphisms.

Angiotensin II↗
PubMed2002

Angiotensin II angiogenic effect in vivo involves vascular endothelial growth factor- and inflammation-related pathways.

Although accumulating lines of evidence indicate the proangiogenic role of angiotensin II (Ang II), little is known about the molecular mechanisms associated with such an effect. This study aimed to identify molecular events involved in Ang II-induced angiogenesis in the Matrigel model in mice. C57Bl/6 female mice received a subcutaneous injection of either Matrigel or Matrigel with Ang II (10(-7) M) alone, with Ang II and an AT1 receptor antagonist (candesartan, 10(-6) M), or with Ang II and AT2 receptor antagonist (PD123319, 10(-6) M). After 14 days, angiogenesis was assessed in the Matrigel-plug by histological evaluation and cellular counting. Ang II increased by 1.9-fold the number of cells within the Matrigel (p < 0.01 versus control). Immunohistological analysis revealed the presence of macrophages, endothelial and smooth muscle cells, and the development of vascular-like structure. Such an angiogenic effect was associated with an increase in vascular endothelial growth factor (VEGF) (1.5-fold, p < 0.01), endothelial nitric oxide (eNOS) (1.7-fold, p < 0.01), and cyclooxygenase-2 (1.4-fold, p < 0.05) protein levels measured by Western blotting. Conversely, Ang II treatment did not affect MMP-9 and MMP-2 activity, assessed by zymography. Blockade of AT1 receptor completely prevented the Ang II-induced angiogenesis and protein regulations, whereas that of AT2 was ineffective. Administration of VEGF neutralizing antibody (2.5 microg ip twice a week) and cyclooxygenase-2 selective inhibitor (nimesulide, 30 mg/L) also hampered Ang II proangiogenic effect. In addition, Ang II-induced cell ingrowth was impaired by treatment with nitric oxide synthase inhibitor (L-NAME, 10 mg/kg/day) and in eNOS-deficient mice. Therefore, in an in vivo model, Ang II induced angiogenesis through AT1 receptor, which involved activation of VEGF/eNOS-related pathway and of the inflammatory process.

Angiotensin II↗
PubMed2001

Selective microvascular dysfunction in mice lacking the gene encoding for desmin.

The intermediate filament desmin has a key role in the integrity and contractility of skeletal and cardiac myocytes. Its absence or aggregation leads to cardiomyopathies. In arteries desmin is distributed heterogeneously; vascular disorders might also occur in its absence. We studied endothelial and muscular functions in arteries from mice lacking desmin (des-/-), compared with control (des+/+). Carotid and mesenteric resistance arteries were mounted in vitro in arteriographs. Desmin was located exclusively in smooth muscle cells. In arteries from des-/- mice, pressure-induced (myogenic) tone was unchanged, but agonist-induced tone decreased in resistance arteries (no change in large arteries). Flow (shear stress)- and acetylcholine-induced, endothelium-dependent dilation, as well as endothelium-independent dilation, were also decreased in resistance arteries. To our knowledge, this is the first study of vascular contractile and dilatory functions in arteries lacking desmin. Although vascular reactivity was normal in large arteries, it decreased strongly in small resistance arteries. Thus, desmin is required in vascular smooth muscle cells and in resistance arteries, for efficient control of vascular tone and consequently for an optimal blood flow supply. This microvascular defect found in the absence of desmin might play a major role in myopathies seen in desmin-related diseases.

Animals↗