| There are more and more preterm infants who have chronic lung disease ( CLD) , because of the increase of the survival rate of super low birth weight infant. Recently, we have no way to prevent the development of this kind of disease. The crux of the problem is to find the season resulting in chronic lung disease. The change in the pathology of chronic disease is fibrosis and alveolus development dysplasia of the lung. These changes result from multiple reasons. Platelet - derived growth factor can accelerate the development of fibrosis cells. Research with animal models has shown that the very preterm lung can be acutely injured by either oxygen or mechanical ventilation, resulting in interference with or inhibition of lung alveolar and vascular development. We want to observe the changes of platelet - derived growth factor (PDGF) and platelet - derived growth factor receptor (PDGFR) in preterm infant lung of prolonged hyperoxia exposure and find out the relations between of platelet - derived growth factor and platelet - derived growth factor receptor and chronic lung disease. It is not easy to get the lung tissues of preterm infants, so we use preterm rats doing our experiment. We expect to see the same pathophysiology changes in preterm rat lung with in preterm infant lung. We want to do some work to determine priorities for future research.AbstractObjectiveWe want to study the changes of platelet - derived growth factor and platelet - derived growth factor receptor in preterm rats exposed hyperoxia whose lungpathologic changes were similar with chronic lung disease. To research the relationship between platelet - derived growth factor and platelet - derived growth factor receptor in the lung of chronic lung disease and that of healthy lung in preterm rats.MethodsThe preterm rat pubs at 21 - d gestation were assigned randomly into hyper-oxia ( FiO2 > 90% T 25 - 27oC) continuously is hyperoxia group, there are 55 preterm rat pubs, and there are 50 preterm ratpubs at 21 ?d gestation were exposed atmosphere(FiO2 =21% ) is control group, the other conditions in control group is the same with hyperoxia group. We selected randomly 5 animals from each group at Iday, 3days, 7days, 14days and 21 days. They were killed with an overdose of chloral hydrate (10% , 1 ml/kg). We get their lung tissues and fetch at least 10 pieces from similar section of each lung, For microscopic studies , some of the pieces made for hematoxylin - eosin staining. The coded slides of lung at postnatal 1, 3, 7, 14 and 21 days were measured by means of immu-nochemical technology for platelet - derived growth factor and platelet - derived growth factor receptor. The values of platelet - derived growth factor and platelet - derived growth factor receptor were assessed with semi - quantitative analysis by photographic analysis system ( MetaMorph/C - 5050/BX41 made of UIC/0-LYMPUS US/JP) , 5 microscopic fields were observed every piece. The data were analyzed, we want to find the difference between the hyperoxia group and control group. We expect to know the difference of the preterm rats with different days in hyperoxia in the same group.ResultsThere exist fibrosis and alveolus development dysplasia of the lung in preterm infants in hyperoxia group. These changes were in accord with the pathologic changes of chronic lung disease in human infans. As immunochemical stain analysis result of lung tissue showed that there is no difference between hyperoxi-a group and control group at 1day, 3 days ( P>0.05). There is significant dif-ferent between the two groups at 7days, 14days, 2Iday (P < 0. 05). In the same group, there is remarkable difference of the expression of platelet - derived growth factor and platelet - derived growth factor receptor between at 7 days and at 3days (P <0.05). There is on significant different between 1day and 3days, 7days and 14days, 14days and 21 days ( P>0.05).ConclusionThe fibrosis lung model of the preterm rat has the same pathlogic changes with that of the newborn who has chro...
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