死后5～36 h人脑细胞DNA降解含量的图像分析

目的通过对死后5～36 h脑细胞降解后残存DNA含量的定量分析来推断其早期死亡时间.方法选取32例已知死亡时间的人体脑组织,在死后5～36 h内每小时进行细胞学涂片、Feulgen-Vans染色,采用图像分析技术检测反映脑细胞核DNA含量的平均光密度、积分光密度、平均灰度等灰度参数,分析脑细胞残存DNA的含量与其对应的死亡时间的变化规律.结果在5～36 h内平均光密度、积分光密度随死亡时间的延长而逐渐减小、平均灰度逐渐增大,且其均值均与死亡时间显著性相关,并得出对应的回归方程.结论反映人脑细胞DNA含量改变的灰度参数均与死亡时间有明显的相关性,是推断早期人体死亡时间的有效的定量指标.

Changes of DNA content of human brain cells in different postmortem interval by image analysis

Objective To analyze changes of DNA content in human brain nuclei and seek a new experimental method to deduce the postmortem interval (PMI) by computer image-analyze technique. Methods The brain tissue from 32 cadavers with the accurate PMI, was sampled and smeared respectively every hour within the first 36 h after death, fixed with cold Carony fixation, stained by Feulgen-Vans method. Three detective indexes of DNA in brain nuclei were detected by using the image-analyze instrument, including integral optical density (IOD), average optical density (AOD), average gray (AG). Results IOD and AOD in the human brain nuclei declined regularly with the prolongation of dead time in 36 h, whereas AG rose. There was a definite relationship between PMI and gray parameters (IOD, AOD and AG). Conclusion Gray parameters (IOD, AOD and AG) were proved to be preferable indexes to study the DNA degeneration rate of the brain nuclei in 36 h after death and estimate PMI accurately.