人体死后肝细胞DNA含量与死亡时间关系的研究

A study on the relationship between the changes of DNA content in human liver cells and the postmortem interval

目的研究人体死后肝脏细胞DNA含量变化与死亡时间的关系及影响因素。方法选取46例已知死亡时间的人体肝脏，根据离体肝脏所处的环境温度分为12—19％（A组）和20—27％（B组）两组，每组23例。在死后24～72h内每隔4h穿刺取肝组织1次，制成细胞悬液，经RNA酶消化，PI染色后，用流式细胞仪测定被检测细胞中含不完整DNA的细胞数所占百分比，所得数据经Exp032V1．2软件计算N值。结果死后24～72h肝细胞N平均值，A组从10．91％增至49．72％，B组从16．22％增至69．63％。两组N平均值随死亡时间的延长均逐渐增高，与死亡时间有相关性，A组r值为：0．598，B组r值为0．77357。并且建立了不同环境温度对应的回归方程。结论在不同环境温度下，死后24～72h内人体肝脏细胞DNA降解均随死亡时间的延长和环境温度的升高而逐渐加快，相关数据可望为死亡时间推断提供一定参考依据。

Objective To study the changes of DNA content in human liver cells and the postmortem interval（PMI） and analyze the influence of the circumstance temperature to DNA degradation after death. Methods 46 cadavers livers were collected with known the accurate PMI. According to temperature 12 -19℃ （group A） and 20 -27℃（group B）in circumstance, The livers were put into two groups, each 23 livers. The livers were stick for got liver cells every 4h or 8h within 24 -72h period. Cell suspensions were made, digested by RNase, stained with PI, analyzed by Elite ESP flow cytometer. Ceils containing fragment DNA were counted and the ration （N） were then obtained. Results In 24 -72h after death, at 12 - 19℃ ,the average of N was increased from 10.91% to 49.72% ;at 20 - 27℃ ,it was increased from 16.22% to 69.63%. At different temperature ,along with the prolongation of the PMI, the value of N was increased. There was a correlation between the N value and PMI, the r value of group A is 0. 598, and the r value of group B is 0. 773 57. The equations were obtained at the different temperature. Conclusion After death, the degradation lever of the nuclear DNA of human liver has a definite relationship with PMI. The higher the temperature is, the quicker the degradation of nuclear DNA is. The method from this experiment is credible to estimate PMI. But because there are some facts to affect postmortem interval, more evidence is needed to support the result.