The role of intestinal bacterial heat production in confounding postmortem temperature measurements

To assess the influence of anaerobic bacterial heat production in human stools as a confounding factor in postmortem rectal temperature measurements, in vitro experiments were carried out with human stools incubated at 37 degrees C for 6 h and at decreasing temperatures simulating a postmortem body cooling. Although a statistical significant heat production was observed, it was not relevant enough to explain a postmortem temperature plateau or a substantial rise in the postmortem body temperature. The experiments suggest that stools merely reflect the environmental thermal changes rather than producing bias and confounding by a bacterial heat production.     

Rectal temperature time of death nomogram: sudden change of ambient temperature

Cooling experiments on dummies known as body-like cooling were performed with sudden decrease and increase of ambient temperature in the order of 15 degrees C. In the case of a sudden decrease of ambient temperature, a second 'temperature plateau' occurs which is shorter than the known plateau at the beginning of body cooling. The cooling curves can be described mathematically by a three-step procedure based on the two-exponential term of the 'nomogram method'. The second plateau at the beginning of the second cooling phase in sudden decreased ambient temperature requires a lower value of the constant A (1.15) compared with the known value (1.25) at the beginning of body cooling. In the case of a sudden increase of ambient temperature in the order of 15 degrees C no procedure could be found to model the cooling curves mathematically.     

磁共振波谱技术推测不同温度下的死亡时间

目的利用单体素质子磁共振波谱技术推断不同温度下的死亡时间(postmortem interval,PMI),探讨不受外界环境温度影响下推断PMI的可行性。方法选取24只白兔,分为A组(10℃)、B组(30℃),利用磁共振单体素波谱测定死后0.5、1、2、4、6、8、12、16和24h脑内N-乙酰天冬氨酸(N-acetyl-aspartate,Naa)、胆碱复合物(Choline,Cho)、磷酸肌酸和肌酸(phosphocreatine and creatine,Cr)峰下面积(相对含量)及各代谢物之间相对含量的比值。结果在死后24h内Naa和Cr峰下面积随PMI的延长而减少,Naa/Cr、Cho/Cr随PMI的延长而降低。回归分析:自变量为Naa/Cr的二次多项式方程为:y=0.0019x2-0.803x 1.4498(R2=0.962);自变量为Cho/Cr的二次多项式方程为:y=-0.0024x2 0.926x 1.1777(R2=0.986)。用Naa/Cr的方程推测PMI,当PMI<24h时,平均偏离时间为2.10～37.90min,用Cho/Cr的方程推测PMI,当PMI<24h时,平均偏离时间为1.69～40.87min。结论Naa/Cr、Cho/Cr的死后变化与时间呈强相关性且受环境温度影响不大,可用于不同温度下PMI推断。     

Estimation of the time since death: sudden increase of ambient temperature

This work presents a procedure for the postmortem interval estimation in the presence of a rapid increase of ambient temperature occurred during the cooling phase. The resulting disturbance produced on the cooling curve is proved to obey a two-exponential law and is removed from the actually measured body temperature. This yields a theoretical/modified body temperature, which enables the estimation of the time since death by means of the standard Nomogram method.     

Cooling rates of the ear and brain in pig heads submerged in water: implications for postmortem interval estimation of cadavers found in still water

The state of the art for determining postmortem interval in submerged bodies reflects a serious lack of studies. The objectives of the present study were therefore to study cerebral and tympanic cooling in water and its relation to cooling in air, in a pig model. First of all, cerebral and tympanic cooling on a single head and on an entire body were compared and proven to be very similar in air and in water. Nine pairs of heads were then exposed to 9 temperature intervals from 0 degrees C to 20 degrees C. For every set temperature, one head was placed in water, the other in "ambient" air in a thermostatic chamber. Ear and brain temperature were simultaneously measured every 10 minutes during 8 hours. Results showed that both in air and in water, cooling curves were almost exponential, regardless of the site (ear or brain) or the environmental temperature. Cooling was always more rapid in water than in air. Cerebral and tympanic cooling always had a correlation coefficient of 0.98-0.99. Assuming that these cooling patterns are applicable to man, this research may provide a starting point for postmortem interval estimation in submerged cadavers.     

不同温度下大鼠脑组织RNA降解与早期PMI的相关性

目的探讨大鼠脑组织8种RNA指标,在不同温度下的表达水平与早期死亡时间(PMI)的相关性。方法将222只SD大鼠随机分为对照组(死后0 h)和4个实验组,实验组断颈处死后分别置于5℃、15℃、25℃和35℃的环境中,于死后1~24 h内9个时间点提取脑组织RNA,利用实时荧光定量PCR技术检测8种RNA指标(β-actin、GAPDH、RPS29、18S rRNA、5S rRNA、U6 snRNA、miRNA-9及mi RNA-125b)的表达水平,ge Norm软件选取合适内参,SPSS软件对内参标准化RNA指标进行回归分析,R软件构建推断PMI的数学模型,另选6只已知PMI的SD大鼠予以验证。结果 5S rRNA、miR-9和mi R-125b表达稳定,可作为内参指标。β-actin和GAPDH具有良好的时序性降解规律,在24 h内随PMI延长不断降解。R软件拟合得ΔCt值随PMI和温度变化的数学模型可用以推断PMI。运用β-actin和GAPDH验证模型的平均误差率分别为14.1%和22.2%。结论β-actin和GAPDH表达水平与PMI和环境温度相关性良好。本研究建立的数学模型可为温度变化条件下的早期PMI推断提供参考。     

不同温度下离体人静脉血ATP含量与死亡时间的关系

目的探讨在环境温度变化条件下,人体静脉血ATP降解与死亡时间的关系。方法健康志愿者48名,随机分为6组,肱静脉取静脉血,置于10℃、15℃、20℃、25℃、30℃和35℃下保存;每4h应用ATP检测仪对不同温度下的ATP含量进行检测;应用SPSS统计软件进行回归分析,MATLAB软件进行差值函数分析拟合。结果各温度组ATP值随死亡时间延长均呈下降趋势,从取血即刻的1 573.683 E-13mol/L,降至6.00 E-13mol/L左右,所经历的时间分别为236h(10℃)、163h(15℃)、124h(20℃)、92h(25℃)、72h(30℃)和64h(35℃),对所得数据进行回归分析,得到各温度组下ATP含量变化与PMI关系的二元三次曲线方程(R2范围为0.976～0.990);进行差值拟合,得到10～35℃范围内ATP含量变化与PMI关系的三元四次曲面方程。结论在不同温度下,人体静脉血ATP降解与PMI关系符合三元四次方程分布,利用差值函数拟合的方法可在温度变化条件下进行死亡时间推断。     

The theoretical aspects of the time dependent Z equation as a means of postmortem interval estimation using body temperature data only

It has been clearly demonstrated that the rectal cooling curve does not obey Newton's Law, which is exponential. The first success in modelling rectal cooling mathematically was achieved by Marshall and Hoare [1]. An amendment was made to the simple exponential curve which led to a good mathematical model, exhibiting the three main sections of rectal cooling, i.e. lag, linear and quasi-exponential. The resultant method of postmortem interval estimation required a knowledge of the body mass and height. The present study has led to a totally different amendment to Newton's Law, which provides a means of postmortem interval estimation from body temperature data only. The derivation of the method, with a background on Newton's Law follows.     

Experimental forensic and bioanthropological aspects of soft tissue taphonomy: 1. Factors influencing postmortem tissue desiccation rate.

Euthanized rats' carcasses were exposed in an environmental chamber to multiple variables including: (1) position, (2) enveloping clothing, and (3) soil interment in an effort to determine the individual variables' effect on postmortem rate of body and visceral organ water loss. Results indicated that body water loss was enhanced by a horizontal position versus vertical, probably because of wider spread of bacteria- and enzyme-laden abdominal fluid secondary to diaphragm digestion with consequent greater tissue digestion and liquefaction. Clothing also accelerated the desiccation rate. Desiccation was about equally as effective by soil interment as by air exposure, though simulating windy conditions by tripling the air flow rate resulted in much more rapid desiccation in the air-exposed specimen. These studies suggest that the single most important factor influencing postmortem body water loss rate is the environment at the skin surface that acts to enhance or impair water removal from the skin surface and thus influences the water concentration gradient between the skin and underlying deeper tissues.     

不同环境条件下大鼠死后皮肤生物力学特性改变

目的死亡时间的推测是法医病理学研究的重点和难点。皮肤具有一定生物力学特性,是机体死后分解破坏发生较迟的部分。本研究观察不同环境条件下死后大鼠皮肤生物力学特性的改变,探索其与死亡时间的关系。方法系统测试雌性SD大鼠在不同环境条件下（A组较高环境温度,B组较低环境温度）的死后皮肤生物力学特性。结果 A组大鼠皮肤死后张应力、延伸率在死后1d内先降低后升高,1d～6d逐渐降低,6d～7d略呈上升趋势;B组大鼠皮肤死后张应力在死后2d内先降低后升高,2d～16d逐渐降低,16d～20d略上升。结论 A组的张应力、延伸率和B组的张应力、应变能密度均表现出与死亡时间较好的相关性,是较好的推测死亡时间的生物力学参数。     

不同环境条件下大鼠死后皮肤大体和组织学改变

目的研究观察大鼠在不同环境条件下死后不同时间其皮肤大体、组织学的改变,为推测较长的死后间隔时间建立实验动物依据。方法观察雌性SD大鼠在不同环境条件下的死后变化,并间隔一定死后时间取皮、染色和镜下观察。结果死后发生骨、软组织分离,A组约需35d,B组需13d。皮肤有形细胞成分和附属器完全分解破坏,A组约20d,B组7d。胶原纤维在A组死后40d（B组12d）仍有部分保留完整。结论环境温度差异是造成A、B两组发生死后改变时程不同的主要因素,利用皮肤大体、组织学改变可望较系统和准确的推测晚期死亡时间。     

Realization of an adaptive method of simulating the process of temperature change of a cadaver on a microcomputer

Programme based on mathematical model of the process of dead body temperature changing was developed for estimation of postmortem interval. Automatic retrieval of problem solution was performed on programmable microcalculators of "Electronica MK-61" type using adaptive approach. Diagnostical accuracy in case of dead body being preserved in permanent cooling conditions is +/- 3%.     

Factors influencing the precision of estimating the postmortem interval using the triple-exponential formulae (TEF). Part I. A study of the effect of body variables and covering of the torso on the postmortem brain, liver and rectal cooling rates in 117 forensic cases

Brain, liver, rectal and environmental temperatures were continuously monitored under controlled conditions, in 117 forensic fatalities, for up to 60 h after death. Cases were studied either naked (63%) or covered with two blankets (37%). Bodies were classified into fat and thin groups. Statistical analysis and curve-fitting of the data yielded the average triple-exponential formulae for each body site and each body group. The effects of covering of the torso and body parameters such as weight, height, surface area and 'cooling size factor' (Z) on postmortem cooling are assessed and discussed. Results show that covering of the torso has a significant influence on the rate of postmortem cooling, however, there is no good correlation between the body variables and the cooling rate.     

Study of cathepsin A, B and D activities in the skin wound edges. Its application to the differential diagnosis between vital and postmortem wounds

The aims of the authors in this paper has been to check the diagnostic ability of the Cathepsin A, B and D concentrations in the skin wound edges to the differential diagnosis between vital and postmortem wounds. We have studied 56 domestic pigs grouped in seven experimental series consisting of 8 animals in each, according to the time (0, 5, 15, 30 min and 1, 3 and 6 h) after the injury. The enzymatic activities were investigated following the methods by Bowen and Davison Biochem. J., 131 (1973) 417-419, Suhar and Marks J. Biochem., 101 (1979) 23-30 and by Anson (modified by Yamamoto, Eur. J. Biochem., 95 (1979) 459-467) for Cathepsin A, B and D, respectively. For the differential diagnosis between vital and postmortem wounds, our results showed that the most useful markers studied are the Cathepsin A and D activities, Cathepsin D that of the first one.     

Factors influencing the precision of estimating the postmortem interval using the triple-exponential formulae (TEF). Part II. A study of the effect of body temperature at the moment of death on the postmortem brain, liver and rectal cooling in 117 forensic cases

The temperatures of three body sites, namely, the brain, liver and the rectum as well as the temperature of the environment were continuously monitored, every 5-10 min, in 117 forensic cases commencing soon after death and in most cases, within 45 min postmortem. The body temperature at the moment of death was empirically determined by a computer-based extrapolation method. Thus, temperature data for the first 3h of each body site were fitted to single-exponential equations and the fitted curve was extrapolated backwards to obtain the intercept on the Y-axis (the temperature axis). The effect of body temperature at the moment of death on postmortem cooling rate is examined and factors influencing body temperature at death are discussed. Forensic fatalities associated with hyper and hypothermia are reviewed briefly.     

Analysis of eight STR loci in two Hungarian populations

A collection of eight STR loci (D3S1358, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820) was used to generate allele frequency databases for two Hungarian population samples, Caucasians from the Budapest area and Romanies from Baranya county. During the analysis two intermediate sized alleles and a sequence variant allele were observed at the D7S820 locus. All three types of allelic variants were found to have modification (deletion, insertion, transversion) in the same block of a (T)(9) stretch located within the 3' flanking region of each allele, which may indicate a possible higher mutation rate of this (T)(9) block. For the loci D3S1358 and D7S820 the Romany population database showed departures from Hardy-Weinberg equilibrium. The forensic efficiency values for the Romany population were slightly different from those found in the Hungarian Caucasian population. Comparing the allele frequency values by G-statistic, calculating the F(st) indices and with the pairwise comparisons of inter-population variance, the two Hungarian populations could be distinguished using data of the eight STR loci.     

Spectroscopic determination of skin viability. A predictor of postmortem interval

We have demonstrated that skin viability decreases at a measurable rate following death in an animal model. The decreased skin viability was measured by fluorescein diacetate and ethidium bromide using fluorescence emission spectroscopy. There is significant decrease of the fluorescence intensity of the fluorescein diacetate assay between the 1-4 h, the 6-24 h, and the >40 h time points postmortem. For times between 6-24 h and >40 h postmortem the ethidium bromide assay showed consistent and significant increases in signal. The fluorescence measurements in this study showed that under the experimental conditions the time of death could be determined for <4, 6-24, and >40 hapotmotrem. The application of these assays in the field will require further study of the environmental factors.     

Dermal surface in electric and thermal injuries. Observations by scanning electron microscopy

The dermal surface (after enzymatic digestion of the dermo-epidermal junction) in electric and heat lesions is described. There do not appear to be elements that help in forming a precise differential diagnosis. It is possible, however, to differentiate these lesions from all traumatic cutaneous injuries and some limited nontraumatic lesions (e.g., verrucae). Remarkably good preservation of the dermal surface even in an advanced state of decomposition does suggest the possibility of certain diagnosis of electric and heat lesions even when postmortem phenomena have greatly damaged or even totally removed the epithelial part of the skin.     

Dominance of pre-analytical over analytical variation for measurement of methadone and its main metabolite in postmortem femoral blood

On the basis of simultaneously sampled postmortem blood specimens from the left and right femoral veins the pre-analytical variation of methadone measurements was evaluated and compared to the analytical variation. The material consisted of a series of 27 duplicate samples from routine autopsy cases comprising mainly drug addicts. A chiral LC-MS/MS method was used for measurement of the R- and S-enantiomers of methadone and its main metabolite 2-ethyl-1,5-dimethyl-3,3-diphenylpyrrolinium (EDDP). The analytical CV% was determined to be in the range 3-4% for methadone enantiomers and 4-6% for EDDP enantiomers. The total measurement uncertainty (CV(T)) was estimated from the pre-analytical variation (CV(PA)), analytical variation proper (CV(A)), and variation related to calibration (traceability) (CV(Cal)) according to the relationship CV(T) = [CV(2)(PA) + CV(2)(A) + CV(2)(cal)](0.5). Uncertainty related to calibration concerned a component related to the purity of drug reference compound and a contribution from the production of calibrator solutions (CV(Cal)<1%). Pre-analytical sampling variation was estimated from the duplicate measurements of blood samples after subtraction of the analytical component. The pre-analytical variation amounted to a CV% of 19-21% for R- and S-methadone and 30-38% for R- and S-EDDP, i.e. considerably larger than the other components. Due to the squared addition principle, the resulting total uncertainty (CV(T)) became largely identical to the CV(PA), i.e. 19-21% for R- and S-methadone and 31-38% for R- and S-EDDP enantiomers. Accordingly, CV(T) exceeded CV(A) by a factor 5 or more. Dominance of the pre-analytical component of variation may also be likely for other compounds measured in postmortem blood samples. Thus, the width of the 95%-uncertainty interval (+/-2CV(T)) for a postmortem measurement is largely determined by the pre-analytical component of variation. This should be kept in mind when judging on the uncertainty of postmortem measurement results.     

不同温度下兔玻璃体液K~+浓度与死亡时间的关系研究

目的探索在不同环境温度条件下,玻璃体液中钾离子浓度变化规律与死亡时间的关系。方法家兔处死后分别置于5℃、15℃、25℃和35℃温度下保存,在0~120h内每12h双眼交替微量提取玻璃体液80~100μL;应用罗氏DPPI生化分析仪检测玻璃体液中K~+的浓度;应用插值函数进行分析拟合,建立死亡时间推断方程。结果各温度组家兔玻璃体液中K~+浓度随死亡时间延长均呈上升趋势,对所得数据进行插值拟合,在5℃~35℃的温度变化区间内,K~+浓度变化与PMI关系的三元五次曲面方程:f(x,y)=-1.998e~(14)+1.345e~(12)x+5.902e~(13)y+0.005 585x~2-4.509e~(11)xy-3.876e~(12)y~2-0.000 286 8x~3+0.003 545x~2y+4.406e~(10)xy~2-1.746e~(10)y~3+2.669e~(-6)x~4-1.568e~(-5)x~3y-0.000 177 1x~2y~2-1.64e~9xy~3+6.669e~9y~4-8.672e~(-9)x~5+4.467e~(-8)x~4y+2.354e~(-7)x~3y~2+2.459e~(-6)x~2y~3+2.05e~7xy~4-1.214e~8y~5(R~2=0.995 6),其中温度为自变量x,K~+浓度值为自变量y,PMI为因变量f(x,y)。结论在5℃~35℃的环境温度区间内,家兔眼玻璃体液中K~+浓度变化与死亡时间关系符合三元五次方程分布,利用插值函数拟合的方法可将环境温度作为参数,实现在环境温度变化条件下进行死亡时间推断。