小鼠心肌细胞核DNA变化与死亡时间的关系

Relationship between the Postmortem Interval and Nuclear DNA Changes of Heart Muscular Cells in Mice

目的监测小鼠死后细胞核DNA降解的情况,探讨死后细胞核DNA降解的一般规律。方法应用单细胞凝胶电泳(SCGE)技术结合荧光显微镜和专业的计算机图像分析技术,测定111只小鼠在死后72h内不同时间点小鼠心肌组织细胞头半径、尾长度、头DNA含量比例、尾DNA含量比例、尾矩、Olive矩、头面积、尾面积八项参数的变化值。结果在个体死亡72h内,测定的八项参数指标均显示细胞核DNA降解速率和程度与死亡时间具有高度的相关性,并获得了更能体现DNA降解趋势的二项式回归方程和多元回归方程,均具有高度的统计学意义。结论应用72h内心肌组织DNA变化与死亡时间之间呈线性关系的各组回归方程,可为法医学推断死后经过时间提供一种新的、客观的、精确的方法和参考依据。

Objective To study the changes of DNA degradation in cells of rats and its relationship with the postmortem interval. Method 8 parameters of cell nuclear（including the tail length, the head radius, the percentage of head DNA,the percentage of tail DNA, the tail moment, the olive moment, the head area and the tail area） were chosen to study their changes in the procedure of DNA degradation in myocardium cells in 111 rats at different postmortem interval from 0 to 72 h by using single-cell gel electrophoresis （SCGE）technology and fluorescent microscope combined with auto-analysis-image system method. Results An evident comet tailing was observed in DNA of myocardium cells after electrophoresis, and their changes in all these 8 parameters of cell nuclear were greatly associated with the extension of postmortem interval,which indicate the degradation rate and degree of DNA in the nuclear has a close relationship with postmortem interval in the periods from 0 to 72h in rats and significant difference were found with those groups （P〈0.001）. Conclusion The equations, which were concluded from our study, indicate the close relationship of degradation rate and degree of DNA in the nuclear with postmortem interval from 0 to 72h, and provide an objective and exact new way to estimate the postmortem interval.