Navegando por Palavras-chave "Endothelium, vascular"
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- ItemAcesso aberto (Open Access)Avaliação microscópica e ultra-estrutural do endotélio de veia safena preparada pela técnica no touch(Sociedade Brasileira de Cirurgia Cardiovascular, 2008-09-01) Silva, Virgílio Figueiredo [UNIFESP]; Ishigai, Márcia Marcelino de Souza [UNIFESP]; Freymüller-Haapalainen, Edna [UNIFESP]; Branco, João Nelson Rodrigues [UNIFESP]; Gaia, Diego Felipe [UNIFESP]; Gabriel, Edmo Atique [UNIFESP]; Romão, Renata Aparecida Leonel [UNIFESP]; Buffolo, Enio [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)OBJECTIVE: Saphenous vein grafts (SV) used in coronary artery bypass grafting have a limited life and vein occlusion may be the final adverse effect. Efforts to develop new techniques to harvest the saphenous vein may improve the viability of the graft. METHODS: Twenty patients were randomly divided into two groups with the objective of evaluating the vascular endothelium. The No Touch (NT) technique consists in removing the saphenous vein with perivascular tissue. The conventional technique consists in harvesting with in situ removal of the perivascular tissue. The standard saphenous vein harvesting procedure used bridged incisions. Characteristics of the vein were considered. Evaluation of the endothelium was achieved by electron microscopy and histologic analysis using hematoxylin eosin staining. The Picrosirius and Masson Trichrome methods were used to analyze subendothelial collagen. RESULTS: Electron microscopy demonstrated that the NT Group had larger non-denudated endothelial areas as well as a smaller number of degraded cells. Histological analysis showed the form and integrity of the saphenous vein layers. A larger amount of collagen fibers were identified in the NT Group. CONCLUSIONS: The NT technique better preserves the saphenous vein endothelium suggesting a more viable graft in the long term.
- ItemAcesso aberto (Open Access)Influência da deleção genética de receptores de cininas no metabolismo de óxido nítrico vascular(Universidade Federal de São Paulo (UNIFESP), 2011-09-28) Loiola, Rodrigo Azevedo [UNIFESP]; Pesquero, João Bosco [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Activation of B1 receptor in the vascular endothelium triggers diverse signaling pathways that results in elevation of intracellular Ca2+ and Nitric Oxide Synthase (NOS) activation, followed by NO production and vasodilation. Although much has been investigated about the B1-induction and functionality during inflammation, the importance of B1 subtype in normal vessels remains unclear. To clarify this question, the present study analyzed endothelial function and endothelial NO generation in B1 receptor knockout (B1 -/-) and Wild Type (WT) mice. Mesenteric arteriolar bed was perfused with Krebs solution and vascular responses to Acetilcholine (ACh), sodium nitroprusside (SNP) and norepinephrine (NE) were evaluated by a data acquisition system. Plasmatic NO levels (μmol/L) were analyzed by NO derivatives nitrate and nitrite using NO Analyzer (NOATM280, Sievers Instruments) and vascular NO generation was assessed in mesenteric arterioles slices using DAF -2 DA, a fluorescent cell permeable dye for NO (arbitrary units, a.u.). NOS activity (pmol/mg.min) was measured by the biochemical conversion of L-[3H] arginine to L-[3H] citrulline in homogenates of mesenteric vessels in the presence of optimal levels of substrate and co-factors. Primary endothelial cells were incubated with DAF-2 DA and images obtained in a confocal microscope were analyzed by optic densitometry (a.u.). Cells were stimulated with ACh [1 mmol/L] in presence or absence of the NOS substrate Larginine, or the co-factor tetrahydrobiopterin (BH4), or the antioxidant compound ascorbic acid. Production of superoxide anion (a.u.) was assessed in endothelial cells incubated with dihydroethidine, a fluorescent cell permeable dye for superoxide anion, in the presence or absence of BH4 or ascorbic acid. Mesenteric arterioles from B1 -/- exhibited a severe impairment of ACh-vasodilation for all tested doses, with no changes in the response to SNP and NE. Circulating NO was markedly decreased in B1 -/- (49.6 ± 10.5*; n=6) vs WT (141.9 ± 17.3; n=6 ), accompanied by reduced basal NO release in mesenteric arterioles from B1 -/- (0.16 ± 0.03*; n=6) when compared to WT (0.58 ± 0.08; n=4). NOS activity was elevated in mesenteric homogenates from B1 -/- (3.4 ± 0.58*; n=4) in comparison to WT (1.9 ± 0.05; n=5). ACh-induced NO release was markedly reduced in primary cultured endothelial cells from B1 -/- (35.8 ± 3.1*; n=4) in comparison to WT cells (66.9 ± 3.2; n=4). NO release in endothelial cells from B1 -/- was reversed by incubation with BH4 (54.3 ± 1.7; n=4) and ascorbic acid (101.8 ± 6.0; n=4), but not by L-arginine, while incubation of endothelial cells from WT with BH4, ascorbic acid or L-arginine had no effect. Elevated production of superoxide anion in endothelial cells from B1 -/- (77,1 ± 2,5*; n=4) in comparison to WT (29,3 ± 6,9; n=4) was reversed by incubation with ascorbic acid (35,3 ± 6,4; n=3). The severe impairment in the endothelial-mediated vasodilation accompanied by decreased NO bioavailability, despite the augmented NOS activity, strongly indicates an exacerbation of NO inactivation. Reduced NO availability may be preceded by exacerbation of NO inactivation by superoxide anion, which can leads to inactivation of BH4 in vascular endothelium, resulting in NOS uncoupling and NOS derived production of superoxide anion.
- ItemAcesso aberto (Open Access)Pré-eclâmpsia: estresse oxidativo, inflamação e disfunção endotelial(Federação Brasileira das Sociedades de Ginecologia e Obstetrícia, 2010-12-01) Oliveira, Leandro Gustavo De [UNIFESP]; Karumanchi, Ananth; Sass, Nelson [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade de Harvard Departamento de MedicinaPreeclampsia is a systemic syndrome characterized by inflammatory and antiangiogenic states. The pathogenesis of preeclampsia involves deficient trophoblast invasion that is responsible for altered uterine blood flow and placental oxidative stress. The damaged placenta produces higher concentrations of sFlt-1, a soluble receptor for VEGF and PlGF that is released in the maternal circulation and is involved in endothelial dysfunction. Actually, all processes involved in inflammation, endothelial dysfunction and oxidative stress are strongly correlated and act in a synergistic way. Recent data have shown that an increase in serum concentrations of sFlt-1 initiates 5 to 6 weeks before the clinical manifestations of preeclampsia and these alterations correlate with a decrease in serum concentrations of PlGF. Therefore, both sFlt-1 and PlGF have been suggested to be useful for an early-diagnosis of preeclampsia. The knowledge about the role of antiangiogenic factors in the pathogenesis of preeclampsia has raised the possibility of a therapy involving these factors.In this article we revisited the pathogenesis of preeclampsia addressing its antiangiogenic and inflammatory states.In conclusion, we correlated these alterations with the higher risk for cardiovascular diseases presented by these women in future life.
- ItemAcesso aberto (Open Access)Preparation of the saphenous vein for coronary artery bypass grafting: a new technique no touch that maintains the vein wall integral and provides high immediate patency(Sociedade Brasileira de Cirurgia Cardiovascular, 2003-12-01) Souza, Domingos S. R.; Dashwood, Michael R.; Tonazi, Alan; Johansson, Benny; Buffolo, Enio [UNIFESP]; Lima, Ricardo; Filbey, Derek; Bomfim, Vollmer; University Hospital of Örebro Cardiothoracic Surgery Division; University Hospital Royal Free College Medical School Molecular Pathology and Biochemical Division; Hospital do Servidor Público Estadual; Universidade Federal de São Paulo (UNIFESP); Hospital Oswaldo Cruz Cardiothoracic Surgery DivisionBACKGROUND: The technique of harvesting the saphenous vein (SV) for coronary artery bypass grafting (CABG) influences the fate of vein grafts. A new no touch (NT) technique of SV preparation was developed where the vein is harvested with a pedicle of surrounding tissue, which protects the vein from spasms therefore obviating the need for distension. METHOD: A prospective randomized study in 156 patients who underwent CABG was performed comparing three SV harvesting techniques. The techniques were conventional (c) (adventitial stripping of the vein, manual distention and storing in saline solution); Intermediate (I) (after adventitial stripping, the vein was left in situ, covered with a papaverine-soaked compress, and stored in heparinized blood); and no touch (SV dissected with its surrounding tissue was left in situ, covered with a saline-soaked compress and stored in heparinized blood). A morphological study of the endothelium was preformed using scanning electronic microscopy and an angiographic assessment of the vein graft patency was performed at 18 months mean follow-up time. Also an immunohistochemistry assessment was performed to identify the enzyme, nitric oxide synthase (NOS) in the vein wall. RESULTS: The preservation of the endothelial cell integrity was greater with the no touch technique than with the other procedures. At angiographic follow up, the patency for NT was 95.4%, 88.9% for grafts in group C and 86.2% for grafts in group I. The immunohistochemistry assessment revealed NOS in all three layers of the vein wall that was prepared by the no touch technique. However, a great reduction of this enzyme in veins treated by the conventional technique was observed. CONCLUSION: The endothelial integrity and NOS activity were better preserved when using the no touch technique for vein graft harvesting. The vasorelaxation and thrombo-resistant activities of nitric oxide (NO) may be responsible for the reduced of vasospasms and improved patency rate. Furthermore, the mechanical properties provided by the cushion of surrounding tissue in graft harvested by NT technique may contribute to the observed high patency rate.