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PURPOSE Newborn rats exposed to hyperoxia during the first days of life have been shown to exhibit not only vasculopathy but also permanent changes in the structure and function of the retina. Given that the rat retina is immature at birth and that the maturation process continues until the opening of the eyes at 14 days of life, this study was conducted to(More)
BACKGROUND AND PURPOSE Oxidant stress, especially in the premature, plays a major role in the pathogenesis of hypoxic-ischemic encephalopathies mostly manifested in the periventricular region. We studied the vasomotor mode of actions of the peroxidation product 15-F(2t)-isoprostane (15-F(2t)-IsoP) (8-iso-prostaglandin F(2alpha)) on periventricular region(More)
Using a video-imaging technique, we characterized the effects of 8-isoprostaglandin F2 alpha (8-iso-PGF2 alpha) on retinal vasculature from piglets. 8-Iso-PGF2 alpha potently contracted (EC50 = 5.9 +/- 0.5 nM) retinal vessels. These effects were completely antagonized by the cyclooxygenase inhibitor indomethacin, the thromboxane synthase blocker CGS-12970,(More)
Microvascular degeneration is an important event in oxygen-induced retinopathy (OIR), a model of retinopathy of prematurity. Because oxidant stress abundantly generates thromboxane A2 (TxA2), we tested whether TxA2 plays a role in retinal vasoobliteration of OIR and contributes to such vascular degeneration by direct endothelial cytotoxicity.(More)
We studied the mechanisms of retinal and choroidal vasorelaxation elicited by nitric oxide (NO) using piglet eyes. The NO donors sodium nitroprusside (SNP) and diethylamine-NONOate caused comparable concentration-dependent relaxation that was partially (approximately 40%) attenuated by the guanylate cyclase inhibitors methylene blue and LY83583 and reduced(More)
In order to understand the molecular basis of the elevated cerebral prostaglandin levels in the newborn, we compared the expression of the mRNAs and proteins of prostaglandin G/H synthases (PGHS), PGHS-1 and PGHS-2, in various regions of the brain and the microvasculature of newborn (1-2-day-old) and juvenile (4-7-week-old) pigs and also measured the(More)
It has been postulated that intracellular binding sites for platelet-activating factor (PAF) contribute to proinflammatory responses to PAF. Isolated nuclei from porcine cerebral microvascular endothelial cells (PCECs) produced PAF-molecular species in response to H(2)O(2). Using FACS analysis, we demonstrated the expression of PAF receptors on cell and(More)
The choroid is the main source of oxygen to the retina. In contrast to the adult, the absence of autoregulation of choroidal blood flow in the newborn leads to hyperoxygenation of the retina. In the immature retina which contains relatively low levels of antioxidants this hyperoxygenation favors peroxidation including the generation of biologically active(More)
Opposing effects have been ascribed to nitric oxide (NO) on retinal microvascular survival. We investigated whether changes in the redox state may contribute to explain apparent conflicting actions of NO in a model of oxygen-induced retinal vasoobliteration. Retinal microvascular obliteration was induced by exposing 7-day-old rat pups (P7) for 2 or 5 days(More)