Objectives: To investigate the effects of injury time, postmortem interval (PMI) and postmortem storage temperature on mRNA expression of glycoprotein non-metastatic melanoma protein B (Gpnmb), and to establish a linear regression model between Gpnmb mRNA expression and injury time, to provide aimed at providing potential indexes for injury time estimation.
Methods: Test group SD rats were anesthetized and subjected to blunt contusion and randomly divided into 0 h, 4 h, 8 h, 12 h, 16 h, 20 h and 24 h groups after injury, with 18 rats in each group. After cervical dislocation, 6 rats in each group were collected and stored at 0 ℃, 16 ℃ and 26 ℃, respectively. The muscle tissue samples of quadriceps femoris injury were collected at 0 h, 12 h and 24 h postmortem at the same temperature. The grouping method and treatment method of the rats in the validation group were the same as above. The expression of Gpnmb mRNA in rat skeletal muscle was detected by RT-qPCR. The Pearson correlation coefficient was used to evaluate the correlation between Gpnmb mRNA expression and injury time, PMI, and postmortem storage temperature. SPSS 25.0 software was used to construct a linear regression model, and the validation group data was used for the back-substitution test.
Results: The expression of Gpnmb mRNA continued to increase with the prolongation of injury time, and the expression level was highly correlated with injury time (P<0.05), but had little correlation with PMI and postmortem storage temperature (P>0.05). The linear regression equation between injury time (y) and Gpnmb mRNA relative expression (x) was y=0.611 x+4.489. The back-substitution test proved that the prediction of the model was accurate.
Conclusions: The expression of Gpnmb mRNA is almost not affected by the PMI and postmortem storage temperature, but is mainly related to the time of injury. Therefore, a linear regression model can be established to infer the time of injury.
目的: 探讨非转移性黑色素瘤糖蛋白B（glycoprotein non-metastatic melanoma protein B，Gpnmb） mRNA表达受损伤时间、死亡时间及死后保存温度的影响，建立Gpnmb mRNA表达与损伤时间的线性回归模型，为损伤时间推断提供潜在指标。方法: 将SD大鼠麻醉后钝性挫伤，随机分为损伤后0 h、4 h、8 h、12 h、16 h、20 h和24 h组，每组18只，大鼠颈椎脱臼处死后各取6只分别保存在0 ℃、16 ℃、26 ℃中，在同一温度下于死后0 h、12 h、24 h重复收集大鼠后肢股四头肌损伤处肌肉组织样本，验证组大鼠分组与处理方式同上。使用RT-qPCR技术检测大鼠骨骼肌Gpnmb mRNA的表达。使用Pearson相关系数评价Gpnmb mRNA表达与损伤时间、死亡时间、死后保存温度的相关性，SPSS 25.0软件构建线性回归模型，验证组数据用于回代检验。结果: Gpnmb mRNA的表达随损伤时间延长而持续增加，表达量与损伤时间高度相关（P<0.05），与死亡时间和死后保存温度基本不相关（P>0.05）。损伤时间（y）与Gpnmb mRNA相对表达量（x）的线性回归方程为y=0.611 x+4.489。回代检验结果证明该模型预测结果准确。结论: Gpnmb mRNA的表达基本不受死亡时间及死后保存温度的干扰，而与损伤时间相关，因此可建立线性回归模型用于损伤时间推断。.
Keywords: forensic pathology; glycoprotein non-metastatic melanoma protein B (Gpnmb); postmortem interval; postmortem storage temperature; rats; wound age estimation.