根据肝脏死后改变推断死亡时间的研究进展

机体死后会发生一系列的改变,是腐败的过程,也是器官组织细胞自溶的过程。在司法实践中,通过研究肝脏死后改变,可以更准确的推断死亡时间,为案件的侦破提供线索。本文综述了近几十年来,利用肝脏死后变化推断死亡时间的研究进展。     

Differences in morphological age-related dental changes depending on postmortem interval.

Morphological methods for age estimation from teeth have been developed and applied to samples without taking the postmortem interval into consideration. We studied differences in morphological age-related changes between fresh extracted teeth and teeth from human skeletal remains in order to develop appropriate dental age estimation methods according to the time after death. Forty-three permanent teeth from dental patients were compared to 37 teeth obtained from human skeletal remains with a postmortem interval from 21 to 37 years. Morphological age-related changes were investigated by measuring variables on intact and half-sectioned teeth. A new computer assisted image analysis procedure to avoid subjectivity was developed to measure variables in sectioned specimens. Dental color, translucency length, attrition, cementum apposition, and secondary dentin showed higher values in teeth from human skeletal remains than in fresh extracted teeth. Variables obtained by morphometric analysis of computer-generated images (tooth length, tooth width, root length, and root area) showed higher values in fresh extracted teeth than in teeth from skeletal remains. The postmortem interval affects age-related morphological changes, and therefore different methods should be used for teeth of unknown postmortem interval.     

运用猪眼视网膜细胞DNA降解程度推断死亡时间

目的运用单细胞凝胶电泳（single cell gel electrophoresis,SCGE）技术观察猪眼视网膜细胞DNA降解规律,推断死亡时间（postmortem interval,PMI）。方法猪死后取眼球放置于避光、温度（15±2）℃、湿度（50±5）%条件下,分别于2、4、6、8、10、12、14、16、18、20、22、24 h提取猪眼球视网膜细胞,进行SCGE,荧光显微镜采集图像,并运用单细胞凝胶电泳图像分析系统（IMI 1.0）进行图像分析。结果死后2～24h,视网膜细胞DNA降解程度随着PMI延长而增加;头DNA含量（%）、LT/LH、IT/IH与PMI的回归方程分别为y=92.227-5.188 x＋0.019 x^2＋0.001 x^3（R^2=0.971）、y=0.035e^0.191x（R^2=0.947）、y=0.099 e^0.264x（R^2=0.955）。结论运用SCGE检测视网膜细胞DNA降解情况有助于推断PMI。     

Analysis of gastrocnemius compound muscle action potential in rat after death: significance for the estimation of early postmortem interval

The estimation of postmortem interval is of great importance in forensic medicine. Changes in the properties of excitable tissue provide another possible means by which the time of death can be estimated. This paper reports the monitorization of the compound action potentials recorded from gastrocnemius muscle by means of sciatic nerve stimulation in rats before and after death. The sciatic nerve was stimulated using rectangular impulses of 0.1ms duration and intensities ranged between 1 and 100mA while the rat was alive. Subsequently, the rat was killed by cervical dislocation. The similar measurement procedure was performed at the moment of death and every 5min after sequentially. There was a progressive decline in amplitude values that began 10min after death. The decrease in the amplitude of the compound muscle action potentials (CMAP) was most prominent especially when elicited with lower stimulus intensities. The mean area of the CMAPs also began to decrease beginning from 15min after death. Fifteen minutes after death, the motor latencies began to prolong. Thirty-five minutes after death, the decline in amplitude and area of mean CMAP was most prominent as the mean motor latency. At the 40th minute, most of the CMAPs were unelicitable. During the early postmortem interval, these amplitude, area and motor latency alterations decrease in the amplitude and area, prolongation of motor latency seems to be well correlated with each other and this was statistically significant. These findings are discussed as possible basis of a forensic method for postmortem interval estimation.     

Compound muscle action potential analysis in different death models: significance for the estimation of early postmortem interval

In this experimental study, we investigated the varieties of excitability of gastrocnemius muscle via sciatic nerve as per different death models (asphyxia, abundant-bleeding and gradual-bleeding) on rats and the significance for the estimation of postmortem interval was evaluated. For this purpose, the rats were applied different stimulus intensities (5, 20, 40 mA) with 0.1 ms duration, before, during and every 5 min after death, using rectangular impulses, and the mean amplitude, onset latency and area values for each compound muscle action potential (CMAP) were elicited. It was detected that amplitude and area increased and onset latencies prolonged in the first postmortem 15 min. From the 15 min, CMAP area and amplitude showed an ever-increasing decrease and the prolongation of onset latencies became apparent. The decrease rate of area and amplitude was found to be statistically significantly different in asphyxia and abundant-bleeding models compared with in gradual-bleeding model, at 30 min measurements. However, there was not any significant difference in onset latency increase rates of three groups. Separately, any significant correlation between the agony and excitability periods among the groups could not be detected. The fact that the increase rate of onset latency did not show a significant difference as per death models indicated that onset latency ratios would be more appropriate criteria in determination of postmortem interval, regardless the reason of death.     

Comparison of chemical methods for determining postmortem interval

Accurate determination of postmortem interval (PMI) is a problem for the forensic thanatologist, especially in unwitnessed deaths. A number of objective chemical methods for determining PMI have been developed, the most widely used being accumulation of potassium in the vitreous humor. The authors previously have reported a chemical method for determining PMI from the predictable accumulation or clearance of the dopaminergic metabolite 3-methoxytyramine (3-MT) in the putamen of the brain. They have extended their previous study to compare directly the accuracy of determining PMI from the level of 3-MT in putamen with the level of potassium in vitreous humor. The data indicate that 3-MT is at least as accurate as, if not more accurate than, potassium accumulation in vitreous humor, although 3-MT levels can be affected by the cause of death and drugs present at the time of death. Nevertheless, determination of both the 3-MT and potassium levels can afford the most accurate method of determining PMI; preliminary nomograms for determining PMI from both variables are presented.     

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。     

利用猪胸主动脉生物力学性能时序性变化推断死亡时间

目的观察分析家猪尸体胸主动脉生物力学性状指标的变化规律,探讨其在死亡时间(PMI)推断中的应用价值。方法采集180根家猪的主动脉,在恒定温度、湿度下,于2～230h之间每间隔12h设置1个取检材时间点组;各组主动脉检材用电子万能材料试验机拉伸检测极限载荷、极限载荷变形、平均力、应力、应变,宽度和厚度等生物力学参数指标;应用多元逐步回归方法进行统计学分析。结果家猪死后230h内,随PMI延长,胸主动脉大体观呈自溶腐败性变色、瘫软、液化趋势。生物力学参数指标中,极限载荷、平均力和应力呈随PMI延长呈明显下降趋势,PMI间隔24h组间比较差异性均有统计学意义(P<0.05),校正决定系数分别为0.923、0.806、0.867,估计标准误差分别为±18.39h、±29.88h、±24.58h,PMI间隔24h组间比较差异性均有统计学意义(P<0.05),其它指标与PMI之间相关性不显著均P>0.05。结论死后230h内家猪胸主动脉的极限载荷、平均力和应力的死后时序性变化,与PMI呈明显的负相关性,可用于PMI推断,其中极限载荷效果最佳。     

DNA定量技术在死亡时间推断中的研究进展

死亡时间推断是法医病理学研究的热点及难点之一.随着分子生物学技术的发展,DNA的定量已广泛应用于死亡时间推断的研究.本文主要对机体死后不同组织和器官中DNA含量随时间的降解情况,以及单细胞凝胶电泳、Feulgen染色图像分析技术、流式细胞仪等近年来新的DNA定量技术应用于死亡时间推断研究中的进展进行了综述.     

小鼠心肌细胞核DNA变化与死亡时间的关系

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。     

家猪死后脑组织GC-MS检测和死亡时间推断的研究

目的利用GC-MS检测死后家猪脑组织的代谢产物,推断死亡时间。方法成年家猪大脑,置于25℃、75%RH的人工气候箱中,于0 h-84 h内,每间隔6 h取材,GC-MS检测各时间点脑组织代谢物变化。结果PCA显示:平台期和窗口期的时间组彼此分开。建立PLS模型,通过VIP> 1且Kruskal-Wallis检验(P <0.05)筛选出18种重要的代谢物,线性回归模型和参数检验均有统计学意义。多元回归方程为:Y_(PMI)=6.610+16.29X_(十八烷酸)+14.56X_(5-氨基缬草酸)+5.517X_(丙氨酸)(R~2=0.909、SE=6.323)或Y_(PMI)=15.78+9.690 X_(5-氨基缬草酸)+86.45X_(亮氨酸)-82.35X_(甘氨酸)(R~2=0.952、SE=4.271)。结论 GC-MS检测出家猪死后脑组织的多种产物与PMI存在显著相关性,证实了其理论和技术推断PMI的可行性。综合多指标多元逐步回归分析和PLS-DA等多元模式分析方法建立PMI推断模型,可提高推断模型的准确性和精确度。     

Improved estimation of postmortem interval based on differential behaviour of vitreous potassium and hypoxantine in death by hanging

Many formulae are available to estimate the relation between the potassium ([K+]) and hypoxantine ([Hx]) concentration in the vitreous humour and the postmortem interval (PMI). Typically these have been based on a correlation test and linear regression using the postmortal interval as the independent variable and [K+] or [Hx] as the dependent variable in order to estimate the confidence interval. However, a recent study has shown that a more precise measurement of PMI can be obtained if [K+] is used as the independent variable. The regression lines obtained from the most recent deceased subjects with forensic relevance received for autopsy in the Institute of Legal Medicine are [K+] = 5.589 + 0.174PMI and [Hx] = 26.459 + 3.017PMI, by changing the variables, we obtain PMI=3.967[K+] - 19.186 (R2 = 0.688, P < 0.001) and PMI = 0.172 [Hx] + 0.170 (R2 = 0.518, P < 0.001). In this paper we propose the cause of death as an extra factor which modifies the relationship and gives even greater precision in estimating PMI. In cases of death by hanging the results are considerably improved with [K+] = 5.224 + 0.225PMI and [Hx] = 15.161+4.957PMI, respectively, and consequently, PMI = 3.631[K+] - 17.334 (R2 = 0.818, P< 0.001) and PMI = 0.153[Hx] - 0.368 (R2 = 0.757, P < 0.001): the slope is less and the precision is obviously enhanced.     

核酸及蛋白质在死亡时间推断中的应用

死亡时间(postmortem interval,PMI)推断一直是法医学研究的重点与难点.机体死亡后,组织细胞发生自溶,核酸等大分子物质发生降解,其中DNA含量呈逐渐下降趋势,与PMI具有一定的线性关系,管家基因β-actin、GAPDH mRNA具有一定的稳定性,也可作为内参照进行PMI推测.本文综述了目前DNA、...     

利用尸体软组织生物力学性状时序性变化推断死亡时间

目的探讨尸体软组织生物力学性状时序性变化规律及其推断死亡时间的可行性。方法将实验大鼠用颈椎脱臼法处死,放置25℃恒温培养箱内即刻、6、12、18、24、30、36、42、48、60、72、96、120、144、168、192h,定时、定位、定向、定形切取大鼠胸部正中皮肤、腹壁肌肉、胸主动脉、结肠和小肠的生物力学试件,用电子万能材料试验机检测各试件的极限载荷、应变、应力生物力学参数。结果除主动脉外,尸体皮肤、肌肉、小肠、结肠的各项软组织生物力学参数均呈明显的死后时序性下降趋势。各参数下降趋势具有显著性差异的＂窗口期＂分别为：极限载荷：死后18h内皮肤、小肠呈下降趋势;24h内肌肉、结肠呈下降趋势;96～168h肌肉呈下降趋势;72～192h结肠呈下降趋势。应变：各组织在24h内均呈下降趋势,其结肠72～192h缓慢下降趋势。应力：皮肤18h内呈下降趋势,肌肉、小肠24h内呈下降趋势,结肠36h内呈下降趋势。结论大鼠尸体软组织各生物力学性状在不同的＂窗口期＂存在时序性变化规律,综合各指标可用于推断相应＂窗口期＂内的死亡时间。     

猪眼玻璃体液钾离子、次黄嘌呤浓度变化与PMI推断

目的 研究猪眼玻璃体液成分变化及其与死亡时间(postmortem interval,PMI)的关系.方法放血处死家猪后取带眼睑的眼球96只,随机分为24组,在避光、温度(15±2)℃、湿度(50±5)%条件下分别放置2～96h,采集玻璃体液,运用全自动生化检测仪、超高效液相色谱检测K+、Na+、Cl-及次黄嘌呤(hy...     

家兔死后眼玻璃体液消光度与死亡时间关系研究

目的 为寻找一种精确推定死亡时间的方法。方法 应用 754分光光度计,在 420nm波长下,检测了 48只家兔死后不同时间的眼玻璃体液消光度,探讨其与死亡时间的关系。结果 眼玻璃体液消光度（ X）与死亡时间（ Y）呈线性正相关（ r=0.983 27, P< 0.05）,在死后 0～ 72小时,眼玻璃体液消光度与死亡时间存在回归关系（ F=116.54, P< 0.05）,直线回归方程为： Y = 453.30X＋ 0.75 [Y为死亡时间 (PMI),单位为小时; X为眼玻璃体液消光度 ]。结论眼玻璃体液消光度的测定可作为推断死后 72小时内死亡时间的参考指标之一。     

离体人胸骨骨髓DNA降解与腐败尸体死亡时间推断的初步研究

目的研究死后胸骨骨髓DNA的降解与较长死后间隔时间(PMI)的关系。方法采用改良Feulgen染色及计算机图像分析技术对离体人胸骨(取材后分别室温搁置0,1,3,5,7d)骨髓DNA含量进行定量检测。结果在较长PMI范围内,人胸骨骨髓DNA含量仍呈现下降规律。结论人胸骨骨髓DNA降解规律可望应用于较长PMI的推断。     

根据蝇类蛆长度变化系数θ推断尸体死亡时间

目的通过动物实验,探寻嗜尸蝇类蛆的生长长度与尸体死亡时间之间的关系,从而为判断尸体死亡时间提供参考依据。方法将实验用犬击毙后观察尸蝇来到犬尸上的时间、产卵时间、卵期、蛆增长到规定长度所需时间。结果证实蛆虫长度与尸体死亡时间存在正相关性,并进而推算出相关系数θ,从而推导出了一个通过蛆虫长度计算尸体死亡时间的公式。结论通过实际案例的验证,通过该公式可以计算出尸体的大致死亡时间。     

Comparison of four skeletal methods for the estimation of age at death on white and black adults

ABSTRACT: When analyzing human adult skeletal remains, it is often difficult to decide whether a single aging method will give a more reliable age estimation than a combination of methods. This study evaluates four macroscopic indicators for age estimation on 218 American White and Black individuals, ranging in age from 25 to 90 years of age, from the Terry collection. Individuals in the sample were selected to have a balanced race, sex, and age distribution. The following aging methods were applied to each skeleton by one experienced observer: the Suchey–Brooks (SB) pubic symphysis method, the Lovejoy auricular surface method, the monoradicular teeth Lamendin (LM) method, and the I?can (IC) method for fourth ribs. The statistical study involved the evaluation of inaccuracy and bias (based on median age) for each age indicator and the combination of methods using Principal component analysis (PCA). Analysis was performed on the entire sample, then by race, then sex, and then age group (25–40 years, 41–60 years, and >60 years). PCA was the most accurate method for both racial groups when all age groups are analyzed together. When the sample was divided into age groups, SB was the most accurate for young adults (25–40 years) and LM was the most accurate for middle adults (41–60 years). After the age of 60, all methods are highly inaccurate, although IC gives the lowest inaccuracy. As regards bias, the study highlights the tendency of all methods to overestimate the age of young individuals and to underestimate in the older age group. No single skeletal indicator of age at death is ever likely to reflect accurately the many factors that accumulate with chronological age. In fact, one must use as many dental and skeletal indicators as possible. However, in order to maximize the potential of each method, in the final evaluation one should consider mainly the method or methods that have a higher accuracy for a particular age range.     

The use of absolute refractory period in the estimation of early postmortem interval

The estimation of the time since death (postmortem interval) is one of the most difficult problems in forensic pathology. Most methods currently employed use temperature-based algorithms intended to model the cooling of the body after death and thus estimate the postmortem interval. These methods are subject to considerable inaccuracy but their reliability can be improved if a range of other observed criteria such as lividity and rigor are also taken into consideration. The aim of the present study was to investigate the feasibility of using the absolute refractory period as an adjunct to the estimation of postmortem interval. The relationship between the `postmortem interval' and the `duration of absolute refractory period' was investigated using the rat sciatic nerve. A strong correlation between the duration of the absolute refractory period and the postmortem interval was observed. When both absolute refractory period and temperature were used in conjunction, the strength of this correlation was increased.