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Background To explore the relationship between the pathological changes of the colon, terminal ileum, lung, liver and kidney, and the changes of Bax, PCNA and PAF in a rat model of NEC. Methods One hundred and forty neonatal SD rats were randomly divided into NEC group and control group (70 in each group). NEC group was given hypoxia, cold stimulation and artificial feeding twice a day for 3 consecutive days. The control group was only fed normally. After modeling, From the 1st day to the 7th day, 10 rats were sampled in each group for pathological examination of colon, terminal ileum, lung, liver and kidney tissue. The levels of Bax, PCNA and PAF were investigated by immunohistochemistry. Results Compared with the normal group, in the NEC group, on the 1st day, the colon, terminal ileum, lung, liver and kidney showed inflammatory damage. On the 5th day, the inflammatory injury was reduced. The inflammation disappeared on the 7th day. There were differences in the time of apoptosis in the intestine. In the intestine, the proliferation of PCNA was weak at first and then strong. Bax in liver and kidney showed marked apoptosis and apoptosis time increased in the lung. The expression of PCNA increased in lung, liver and kidney, and the expression of PAF increased in lung and liver. Conclusions NEC can lead to secondary injury of different degrees in colon, terminal ileum, lung, liver and kidney, and the degree and time of injury and repair were different. In general, organ repair played a leading role on the 4th day after modeling.

Based on the meteor radar, one can study the radiant distribution and the time variant of meteors, investigate space debris and predict the passage time of meteor showers, and so on. By observation of the Kunming meteor radar, the observation data of meteor decay time and the ambipolar diffusion coefficient are consistent with the theories. By analyzing the 571632 meteors observed by Kunming meteor radar, the parameters of meteor are analyzed and the height distribution of meteors model has been constructed, the result predicted by this model agrees with observation data at different months. The work of the paper will be helpful to study distribution of meteor and passage time of meteor showers.