Study On Risk Factor In Retinopathy Of Prematurity And Effect Of Retinal Vessels Development Of New Born Mice In Different Oxygen Concentration

Objective1. To observe incidence and risk factor of retinopathy of prematurity (ROP) inl37 neonatus.2. To study morphologic change of retinal vessel, analysis VEGF genic regulation under different oxygen concentration and clarify pathogenesis of neovascularization in ROP, from different domain of molecular biology and histopathology.Methods1. Clinic part: To exam 137 neonatus fundus, record disease history. Logistic multiple factor gradual regressive analysis was used to evaluate risk factors of ROP.2. Experimental part:(1) Model: 60 P7 C57BL/6J mice were divided into Oxygen-induced ROP model, hypoxia and control group in random, 24 mice were exposed to 75% oxygen for 5 days and then to room air for 5 days, 12 mice were exposed to 8% oxygen for 24 hours, 24 mice were raised at room air.(2) Morphology study: Fluorescent vascular perfusion, retinal stretched preparation and histological section technique were used to observe morphologic change of retinal vessel. To quantization retinal neovascularization, vascular endothelial cellular nucleus which broke through internal limiting membrane(ILM) was counted.(3) Protein expression: Immunohistochemistry technique were used to observe VEGF protein expression in kytoplasm of retinal slice.(4) Gene expression: RT-PCR was used to observe change of VEGF mRNA transcription.Results1. Clinic result: Incidence of ROP was 16.8%. Incidence of ROP was 27.7% in prematurity infant, 54 term birth of newborn did not happen ROP. The risk factor of ROP were gestational weeks , weight at birth and oxygen concentration through logistic multiple factor gradual regressive analysis.2.Experimental result:(DPersistent and higher reproducibility retinal neovascularization can be induced after P7 C57BL/6J mice in 75% oxygen.(2)The method of retina fluorescent vascular perfusion and retinal stretched preparation technique could clear display distribution and shape of the retinal superficial, deep-seated vessels and neovascularization. The morphologic characteristics of retinal vessel in ROP were the superficial and deep-seated vessels center appeared nonperfusion in hyperxia condition, the new vessels appeared junction of perfusion and nonperfusion at midpenphery retina in relative hypoxia condition. The retinal vessels were generally dilation and circuity, especially superficial radial vessels were severity dilating, caliber was unevermess in single episode of hypoxia condition.(3) The histological section showed that retinal surface was missing smooth interface, periphery vessels were blocked and vessels atresia in nerve fiber layer under hyperxia condition, and capillary broken through internal limiting membrane into vitreous, then appeared neovascularization under relative hypoxia condition. The periphery retinal vessels dilated in hypoxia group, few pre-ILM vascular endothelial cell nucleolus was observed.