| Objective: To study the different causes of death(drowning,myocardial contusion)in different time of death in rats after death.Myocardial injury markers and the content changes of myocardial injury markers found in different causes of death in rats,which in order to improve the markers of myocardial injury after death detection of forensic significance.Methods: 75 rats were randomly divided into two groups: the control group(n = 25)were randomly divided into two groups: The experimental group,each group of 25: A Chest attack group(using improved BIM-II biological impact machine closed to combat the rat primordial area,the combat strength of 120Kpa);B Drowning group,the blank control group did not do any treatment,direct neck death,when 6h,12 h,24h,48 h,72h after taking the blood.The experimental group A and B were treated respectively.At 6h,12 h,24h,48 h and 72 h,the rats were treated with HE staining and microscopic observation.The heart blood of each group of SD rats was collected and serum was prepared,and the five kinds of cardiac enzymes and trooping were detected.The measurement data were expressed as mean ± standard deviation,and the differences between the three groups were compared by single factor analysis of variance.the difference was statistically significant which comparison between the two groups,using T test,if P <0.05,showed the difference was statistically significant;for each group of death time and myocardial injury markers linear regression,if R2 ≥ 0.8 that showed the myocardial injury markers and time between the Linear relationship.Conclusion:(1)The establishment of SD rat model of cardiac contusion by using BIM-II type biological machine is a successful and effective method for myocardial contusion.(2)48 hours CK,6 hours LDH,72 hours of GPT,there was no significant difference between the control group and the drowning group of myocardial injury markers(P>0.05);there was no statistical significance between the three groups of CK-MB(P>0.05),cTnT,CK,GOT,LDH indicators in the combat group with the control group,between group and group against drowning most of the time point,the difference was not statistically significant(P>0.05);In GPT,which combat group and drowning group had significant differences on most of the time points(P<0.05).Found on the same cause of death at different time points in group comparison,was statistically significant in three groups of rats after the death of 6h and other difference time points(P<0.05),most of the other time points on myocardial injury markers between most of the difference things was not statistically significant(P>0.05).(3)In the blank control group,the myocardial injury markers,the content of cTnT and LDH was linear with time(R2>0.8).The cTnT and CK-MB contents in the chest percussion group were linear with time(R2>0.8).In drowning group,the content of LDH was linear with time(R2>0.8).In the other groups,the content and time were not linear.However,the content of cTnT increased with the increase of the time of death.Results:(1)the SD rat model of cardiac contusion was successfully established by using BIM-II type biological machine.(2)We found the three Causes of death involved in the study were preserved at the temperature of 20℃、and humidity for 78%,and the cell structure could be identified within 3 days.(3)There was no significant difference in myocardial injury markers within 12-72 hours after death,so the markers of myocardial injury could be used as an auxiliary diagnostic index for 3 days after death.In a linear relationship between myocardial injury markers and In the blank control group,the content of cTnT decreased with the increase of the time of death.(4)The serum myocardial injury markers of SD rats with different death causes showed different trends with the postmortem time.The effect of death should be taken into account when estimating the time of death by serum myocardial injury markers. |
