RESUMEN
Previously we showed L-4F, a novel apolipoprotein A-I (apoA-I) mimetic, improved vasodilation in 2 dissimilar models of vascular disease: hypercholesterolemic LDL receptor-null (Ldlr(-/-)) mice and transgenic sickle cell disease mice. Here we determine the mechanisms by which D-4F improves vasodilation and arterial wall thickness in hypercholesterolemic Ldlr(-/-) mice and Ldlr(-/-)/apoA-I null (apoA-I(-/-)), double-knockout mice. Ldlr(-/-) and Ldlr(-/-)/apoA-I(-/-) mice were fed Western diet (WD) with and without D-4F. Oral D-4F restored endothelium- and endothelial NO synthase (eNOS)-dependent vasodilation in direct relationship to duration of treatments and reduced wall thickness in as little as 2 weeks in vessels with preexisting disease in Ldlr(-/-) mice. D-4F had no effect on total or HDL cholesterol concentrations but reduced proinflammatory HDL levels. D-4F had no effect on plasma myeloperoxidase concentrations but reduced myeloperoxidase association with apoA-I as well as 3-nitrotyrosine in apoA-I. D-4F increased endothelium- and eNOS-dependent vasodilation in Ldlr(-/-)/apoA-I(-/-) mice but did not reduce wall thickness as it had in Ldlr(-/-) mice. Vascular endothelial cells were treated with 22(R)-hydroxycholesterol with and without L-4F. 22(R)-Hydroxycholesterol decreased NO (*NO) and increased superoxide anion (O2*-) production and increased ATP-binding cassette transporter-1 and collagen expression. L-4F restored *NO and O2*- balance, had little effect on ATP-binding cassette transporter-1 expression, but reduced collagen expression. These data demonstrate that although D-4F restores vascular endothelial cell and eNOS function to increase vasodilation, HDL containing apoA-I, or at least some critical concentration of the antiatherogenic lipoprotein, is required for D-4F to decrease vessel wall thickness.
Asunto(s)
Apolipoproteína A-I/fisiología , Hipercolesterolemia/tratamiento farmacológico , Receptores de LDL/fisiología , Vasodilatación/efectos de los fármacos , Transportador 1 de Casete de Unión a ATP , Transportadoras de Casetes de Unión a ATP/fisiología , Animales , Apolipoproteína A-I/farmacología , Arterias/efectos de los fármacos , Arterias/patología , HDL-Colesterol/sangre , Dieta , Hipercolesterolemia/patología , Hipercolesterolemia/fisiopatología , Lipoproteínas HDL/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Óxido Nítrico Sintasa de Tipo II/fisiología , Óxido Nítrico Sintasa de Tipo III , Peroxidasa/sangreRESUMEN
Acute lung injury (ALI) carries a high mortality in critically ill patients. Recent reports correlate elevated concentrations of endothelium-derived microparticles (EMPs) with diseases of endothelial dysfunction. Many of these diseases have ALI sequelae. We hypothesize that EMPs contribute to endothelial cell (EC) dysfunction and development of ALI. To test this hypothesis, we treated isolated vessels with EMPs and examined changes in vasodilation. Endothelial cell cultures were incubated with EMPs and examined for changes in stimulated nitric oxide (*NO) production and nitric oxide synthase (eNOS) activation. Finally, EMPs were injected into rats and mice and lungs examined for ALI. In both mouse and human ex vivo vessel preparations, we found a marked attenuation of endothelium-mediated vasodilation after EMP treatment (4 x 10(6)/mL). This dysfunction was not corrected by pretreatment of EMPs with free radical scavengers. Coincubation of EMPs with EC cultures yielded a three-fold reduction in A23187-stimulated *NO release. Western analysis of these cells showed a corresponding decrease in eNOS phosphorylation at Ser1179 and a decrease in hsp90 association. Measurements of lung permeability, myeloperoxidase activity, and histology of EMPs-treated Brown Norway rats demonstrated pulmonary edema, neutrophil recruitment, and compromise of the endothelial-alveolar barrier as a second hit phenomenon. In C57BL/6 mice, exogenous EMPs caused a significant rise in pulmonary capillary permeability both as a primary and secondary injury. These findings demonstrate EMPs are capable of inducing significant lung injury at pathophysiologically relevant concentrations. Endothelium-derived microparticles inhibit endothelium-mediated vasodilation and *NO generation from eNOS. Once elucidated, EMP mechanisms of inducing ALI and endothelial dysfunction may present new therapeutic targets.
Asunto(s)
Endotelio/fisiopatología , Síndrome de Dificultad Respiratoria/etiología , Animales , Células Endoteliales/metabolismo , Endotelio/metabolismo , Endotelio/patología , Endotelio Vascular/fisiopatología , Activación Enzimática , Humanos , Técnicas In Vitro , Masculino , Ratones , Ratones Endogámicos C57BL , Óxido Nítrico/metabolismo , Óxido Nítrico Sintasa de Tipo III/metabolismo , Tamaño de la Partícula , Ratas , Ratas Endogámicas BN , VasodilataciónRESUMEN
BACKGROUND/PURPOSE: Data on functional outcomes after pediatric pelvic fractures are limited to those obtained at hospital discharge. This study assesses functional status at both hospital discharge and at 6 months after injury. METHODS: A national multicenter prospective study began in February 2002 and is ongoing. Patients completed WeeFIM functional assessments at hospital discharge and at 6-month follow-up as part of this study. This report summarizes preliminary functional assessment results from 20 patients. RESULTS: Patient data were accrued into 3 domains (self-care, mobility, and cognition), which constitute a total raw rating. Significant improvement at 6 months after injury was evident in self-care, mobility, and total raw ratings. This significance remained when total raw ratings were converted to age-adjusted functional quotients. CONCLUSIONS: This preliminary assessment shows that after pelvic fractures, children improve their functional status at 6 months, returning to near-normal status.
Asunto(s)
Evaluación de la Discapacidad , Fracturas Óseas/rehabilitación , Huesos Pélvicos/lesiones , Calidad de Vida , Recuperación de la Función , Accidentes por Caídas , Accidentes de Tránsito , Actividades Cotidianas , Adolescente , Niño , Preescolar , Trastornos del Conocimiento/etiología , Trastornos del Conocimiento/rehabilitación , Femenino , Estudios de Seguimiento , Humanos , Masculino , Limitación de la Movilidad , Alta del Paciente , Estudios Prospectivos , Estados UnidosRESUMEN
Vaso-occlusive events are the major source of morbidity and mortality in sickle cell disease (SCD); however, the pathogenic mechanisms driving these events remain unclear. Using hypoxia to induce pulmonary injury, we investigated mechanisms by which sickle hemoglobin increases susceptibility to lung injury in a murine model of SCD, where mice either exclusively express the human alpha/sickle beta-globin (halphabetaS) transgene (SCD mice) or are heterozygous for the normal murine beta-globin gene and express the halphabetaS transgene (mbeta+/-, halphabetaS+/-; heterozygote SCD mice). Under normoxia, lungs from the SCD mice contained higher levels of xanthine oxidase (XO), nitrotyrosine, and cGMP than controls (C57BL/6 mice). Hypoxia increased XO and nitrotyrosine and decreased cGMP content in the lungs of all mice. After hypoxia, vascular congestion was increased in lungs with a greater content of XO and nitrotyrosine. Under normoxia, the association of heat shock protein 90 (HSP90) with endothelial nitric oxide synthase (eNOS) in lungs of SCD and heterozygote SCD mice was decreased compared with the levels of association in lungs of controls. Hypoxia further decreased association of HSP90 with eNOS in lungs of SCD and heterozygote SCD mice, but not in the control lungs. Pretreatment of rat pulmonary microvascular endothelial cells in vitro with xanthine/XO decreased A-23187-stimulated nitrite + nitrate production and HSP90 interactions with eNOS. These data support the hypotheses that hypoxia increases XO release from ischemic tissues and that the local increase in XO-induced oxidative stress can then inhibit HSP90 interactions with eNOS, decreasing *NO generation and predisposing the lung to vaso-occlusion.