大鼠死后皮肤傅里叶变换红外光谱变化与死亡时间的关系

目的运用傅里叶变换红外(Fourier transform infrared,FTIR)光谱技术分析大鼠死后15d内背部皮肤的光谱变化,以此推断死亡时间。方法大鼠麻醉后颈椎脱臼处死,置于温度为25℃、湿度为50%的环境中,分别于不同时间点提取其背部皮肤,收集红外光谱数据,并利用机器学习技术对数据进行分析。结果大鼠死后背部皮肤组织光谱吸收峰的峰位未发生明显改变,其强度随死亡时间延长而发生变化;偏最小二乘(partial least squares,PLS)回归构建的死亡时间推断模型决定系数(R2)为0.92,预测均方根误差为1.30 d。根据模型中的变量投影重要性(variable importance for projection,VIP)指标确定推断死亡时间的贡献波段为1760~1700cm-1、1660~1640cm-1、1580~1540cm-1和1460~1420cm-1。结论应用FTIR技术检测大鼠死后皮肤组织的光谱学改变,为死亡时间推断提供了一种新的思路。

Relationship between Postmortem Interval and FTIR Spectroscopy Changes of the Rat Skin

Objective To infer postmortem interval(PMI)based on spectral changes of the dorsal skin of rats within 15 days postmortem using Fourier transform infrared(FTIR)spectroscopy.Methods The rats were sacrificed by cervical dislocation after anesthesia,and then placed at 25℃and relative humidity of 50%.The FTIR spectral data collected from the dorsal skin at PMI points were modeled with machine learning technique.Results There was no significant difference of absorption peak location among all the PMI groups but their peak intensities changed as a function of PMIs.The model for PMI estimation was constructed using partial least squares(PLS)regression,reaching a R2 of 0.92 and a root mean square error(RMSE)of 1.30 d.As shown in variable importance for projection(VIP),four spectral bands including 1760-1700 cm-1,1660-1640 cm-1,1580-1540 cm-1 and 1460-1420 cm-1 were determined as important contributions to model prediction.Conclusion Application of the FTIR technique to detect postmortem spectral changes of the rat skin provides a novel proposal for PMI estimation.