Temperature-correction of abdominal impedance: improved relationship between impedance and postmortem interval

The relationship between extracellular abdominal impedance and postmortem interval (PMI) reflects the combined effects, on impedance, of postmortem cooling of the tissues and of autolysis per se. This study was performed in order to eliminate temperature change as a major factor contributing to the time course of postmortem change in abdominal impedance. Dissociation of thermal and autolytic influences was achieved by recording deep abdominal temperature at the time of impedance measurement, followed by correction of all measured impedances to their theoretically predicted values at an arbitrarily chosen temperature of 40 degrees C. Uncorrected abdominal impedance increased from 82+/-12 Ohmz, 1 h after death, to 108+/-21 Ohmz after 12 h. Impedance then decreased to 96+/-23, 89+/-22, 75+/-19, 66+/-21 and 59+/-19 Ohmz at postmortem intervals of 24, 36, 48, 60 and 72 h, respectively. In contrast, corrected abdominal impedance decreased progressively from 63+/-7 Ohmz, 1 h after death, to 61+/-9, 56+/-11, 51+/-10, 46+/-10, 39+/-11 and 35+/-10 Ohmz at postmortem intervals of 12, 24, 36, 48, 60 and 72 h, respectively. The improved relationship between (corrected) abdominal impedance and PMI is of potential value in estimating time since death.     

Estimation of postmortem interval. Temperature-correction of extracellular abdominal impedance during the first 21 days of death

Extracellular impedance of the intact abdomen of rats increased from 79.0+/-7.4Omega, 1h postmortem (i.e. 0.04 day), to 130.5+/-14.4Omega at postmortem interval (PMI)=1 day. Impedance then decreased with time, reaching 64.2+/-9.9Omega at PMI=21 days. The time taken for mean abdominal impedance to decrease below the value at PMI=0.04 day averaged 16 days. It is therefore impossible, using extracellular abdominal impedance alone, to distinguish (in terms of interpolating PMI) between numerically equal impedances on the rising and falling phases of curves depicting impedance as a function of PMI.Correction of measured impedances to their theoretically-predicted values at an arbitrarily chosen temperature of 40 degrees C appreciably diminished the magnitude of the increase in impedance following death. Thus, temperature-corrected abdominal impedance increased from 56.2+/-4.8Omega at PMI=0.04 day to 59.5+/-6.2Omega at PMI=1 day. Impedance then decreased, reaching 29.2+/-4.1Omega at PMI=21 days. The time taken for mean, temperature-corrected abdominal impedance to decrease below the value at PMI=0.04 day averaged 3 days (as opposed to 16 days (see above) in the absence of temperature-correction).These findings are believed to improve the usefulness of extracellular abdominal impedance as a potential tool for estimation of postmortem interval.     

大鼠尸体组织电阻抗的死后变化及与死亡时间的关系

目的探讨躯体组织的电阻抗的死后变化规律，寻找推断死后经过时间的新方法。方法用阻抗测量仪测量大鼠胃壁、腹壁、躯干、胸部、腹部、腹部皮肤、头皮等处不同死后经过时间的电阻抗。结果大鼠躯体组织的电阻抗随着死后经过时间的延长存在规律性变化。这些结果告诉我们，有望通过测量死后人体躯体组织的电阻抗，利用其死后变化规律，推断人体死后经过时间。     

Transcellular and extracellular impedances of the intact abdomen in putrefying rat cadavers

Total (Zt) and extracellular (Ze) abdominal impedances of putrefying rat cadavers, stored at 18.0±0.7°C, were measured at 50 kHz and at 1 kHz, respectively, during the first 7 days of death. Transcellular impedance was calculated from the measured values of Zt and Ze. Total impedance and Ze increased during the first day, and then decreased with increasing postmortem interval, while Zi remained unchanged during the first 3 days before increasing more than 4-fold between 3 and 7 days postmortem. These changes are consistent with net gain of electrolyte by the extracellular fluids and with degeneration of cell membranes which occur postmortem. It is concluded that, during putrefaction, Ze is a potentially more useful index of postmortem interval than Zt or Zi, and that measurement of total abdominal impedance at 50 kHz, rather than at 10 kHz, markedly improves the precision and accuracy of impedance measurement.     

兔死后角膜内皮细胞核DNA降解随死亡时间变化规律

目的研究兔死后角膜内皮细胞核DNA降解与死亡时间的关系。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,检测27只家兔死后48h内不同时间点角膜内皮细胞核DNA降解情况。结果家兔死后角膜内皮细胞产生彗星现象,彗星样细胞出现率于兔死后6h开始逐渐增加。死后6～18h彗星样细胞出现率增加缓慢,死后24～36h出现率上升较快;死后36～48h彗星样细胞出现率上升缓慢,但仍始终保持在较高的水平上(M185.4%),其回归方程为y=-0.0096x2+2.4548x+5.7964,与死亡时间呈正相关(R2=0.9743)。结论家兔死后角膜内皮细胞彗星样细胞出现率随死亡时间增加而逐渐增加。     

A preliminary study of changes in scalp impedance during the early post-mortem period in rats.

An accurate and reproducible technique was used for estimation of scalp impedance (1 kHz) in each of eight rat cadavers, maintained at 9.0 +/- 0.7 degrees C, during the 1 to 144 hour post-mortem period. Scalp impedance increased non-linearly, and in a bimodal manner, between 24 and 144 hours post-mortem. The relationship between scalp impedance and post-mortem interval, and the degree of individual variation in the time course of impedance change, were such that scalp impedance is unlikely to be a suitable tool for estimation of time since death.     

死后小鼠脑组织细胞核DNA变化规律的研究

目的研究DNA降解变化与死亡时间的关系,为法医学推断死亡时间提供一种比较准确可靠的新方法。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,测定了111只小鼠在死后72h内不同时间点小鼠脑组织细胞核头半径（HeadRadius,HR）、尾长度（Tail Length,TL）、头DNA（HeadDNA）含量比例、尾DNA（Tail DNA）含量比例、尾矩（Tail Moment,TM）、Olive矩（Olive Moment,OM）、头面积（Head Area,HA）、尾面积（Tail Area,TA）8项参数的变化值。结果在个体死亡72h内,测定的8项参数指标中尾DNA含量比例、彗星尾长、尾矩、Olive矩、尾面积都呈增加趋势,头半径,头DNA含量比例,头面积均呈下降趋势。上述参数均与死亡时间具有高度的相关性。并将每个参数的测量值进行了多项式运算,获得了更能体现DNA降解趋势的二项式回归方程（P〈0．001）和多元回归方程（P〈0．001）,均具有高度的统计学意义。结论应用本研究提供的72h内脑组织DNA变化与死亡时间之间呈线性关系的各组回归方程,为法医学推断死后经过时间提供了一种新的、客观的、精确的方法和参考依据。     

Linearization of the relationship between postmortem plasma chloride concentration and postmortem interval in rats

A potentiometric titration procedure was employed for measurement of plasma chloride concentrations during the 0-96 h postmortem period in rats. The data revealed antemortem absolute values and postmortem rate of decrease in plasma chloride concentration (PCl) which were almost identical to those in dogs and in man. Expression of the data in the form of a double logarithmic plot of PCl versus postmortem interval (PMI) yielded a linear relationship of high correlation (r = -0.97; P less than 0.001). Attention is drawn to the possibility of utilizing postmortem rate of change in plasma chloride concentration as a means of estimating time elapsed since death.     

大鼠死后脑组织RNA降解与死亡时间推断的研究

目的探讨SD大鼠死后脑组织中甘油醛-3-磷酸脱氢酶(GAPDH)mRNA、18s rRNA含量的比值与死亡时间(PMI)的关系。方法SD大鼠处死后分别置于15℃、20℃环境中,采用TRIzol试剂提取SD大鼠在死后即刻、1、2、3、5、7d时脑组织中的总RNA,采用RT-PCR方法与凝胶图像分析技术检测18s rRNA和GAPDH mRNA的含量,并将二者的比值(GAPDHmRNA/18s rRNA)与PMI进行统计学回归分析。结果SD大鼠死后脑组织中GAPDH mRNA在2d时降解不明显,但到3、5、7d时降解程度显著增加,且随着温度的升高,降解速度增加;而18S rRNA降解缓慢,直到7d仍无显著性降解变化,且降解速度几乎不受温度的影响。对GAPDHmRNA/18s rRNA值(Y)与PMI(X)进行回归相关分析:20℃时,Y=0.62-0.004X(R=-0.981,P<0.001);15℃时,Y=0.965-0.001X(R=-0.709,P<0.001)。结论SD大鼠死后脑组织中GAPDHmRNA和18s rRNA基因的相对稳定性即GAPDHmRNA/18s rRNA值与PMI存在明显相关性。     

Amount of postmortem bleeding: an experimental autopsy study

An experimental autopsy study was performed on 64 cases (55 male, 9 female; average age 51.5 +/- 16.2 years) of sudden natural (38 cases) and asphyxic deaths (26 cases). The study objective was the amount of postmortem bleeding from postmortem cutting of the thoracic aorta, related to the time since death. The amount of postmortem bleeding ranged from 100 to 1300 cm, 440.6 +/- 268.1 cm on average. The time since death up to the autopsy time ranged from 4 to 72 hours, 19.4 +/- 12.9 in average. A statistically significant correlation between the amount of postmortem bleeding and postmortem time interval was stated: Pearson correlation test value r = -0.461 (P = 0.000): the shorter the time interval, the larger the amount of bleeding. The formula of linear regression was estimated according to this correlation: amount of postmortem bleeding (cm) = -9.571 x time since death (h) + 626.659. This proves that the amount of postmortem bleeding (eg, from aortic blunt rupture) could be about 620 cm.     

大鼠死后心肌骨骼肌细胞肌动蛋白变化及与死亡时间的关系

目的　探讨大鼠死后心肌骨骼肌细胞肌动蛋白的变化及其与死亡时间的关系。方法　采用免疫组化S P法和IBSA图像分析系统 ,观测大鼠死后不同时间心肌骨骼肌抗肌动蛋白单克隆抗体 (HHF3 5 )染色变化。结果　在大鼠死后 5 4h内 ,心肌骨骼肌呈不同程度的HHF3 5缺染 ,其面积随死后时间的延长而增大。经对IBSA图像分析数据进行方差分析 (F心肌 =5 88 2 7,F骨骼肌 =3 5 1 2 5 ,P <0 0 5 ) ,具有显著性差异 ;经逐步回归分析 (r心肌 =0 943 ,r骨骼肌 =0 95 8,P <0 0 5 ) ,具有正相关关系。所建方程y心肌 =-3 0 5 68+1 0 0 3x1,y骨骼肌 =-2 4 897+0 986x2 (X为HHF3 5缺染面积均数 )具有统计学意义。结论　在一定时间内 ,大鼠死后不同时间心肌骨骼肌细胞HHF3 5缺染面积 ,随死后时间的延长而增大。     

新西兰白兔死亡后颅脑CT检查与死亡时间关系的研究

目的采用CT扫描动态观察新西兰白兔死亡后脑组织变化,建立利用CT值、脑组织/颅腔面积比,推断死亡时间(PM I)的研究方法。方法通过耳缘静脉注射空气,建立新西兰白兔死亡模型;于死亡后0~120h,运用CT进行头颅平描;选取颅顶面层测定脑组织CT值、脑组织/颅腔面积比。结果死亡后兔脑组织CT值呈双峰样上升、脑组织/颅腔面积比呈不断下降趋势;建立与死亡时间的回归方程:CT值=47.4780-0.1768T+0.0049T2(T/h,CT值/HU)、面积比=99.7368+0.3098T-0.0118T2/100(T/h)。结论CT扫描检查可准确显示兔脑的死后变化;脑组织消失之前,综合运用CT检查指标可用于准确推断死亡时间。     

References for determining the time of death by potassium in vitreous humor

The different statements concerning the slope and intercept of the regression line and the 95% limits of confidence are the reason that potassium in vitreous humor is not used (at least in Germany) as an aid in estimating the time of death. The relationship between the concentration of potassium and the time of death is mainly influenced by antemortem electrolyte imbalances caused by disease and/or duration of terminal episode. The influence of terminal episode is best identified by its duration (Adelson et al., J. Forensic Sci., 8 (1963) 503-514). In order to have a method suitable for every case and to be as precise as possible we looked therefore for parameters in vitreous humor which were stable postmortem and indicating antemortem electrolyte imbalance. Urea is such a parameter, being stable postmortem (Coe, Am. J. Clin. Pathol, 51 (1969) 741-750) and useful as a marker of antemortem electrolyte imbalance. Our investigations on potassium in vitreous humor, including sudden and hospital deaths after chronic lingering disease, revealed 95% limits of confidence of +/- 34 h up to 120 h postmortem. Reviewing only cases with urea less than 100 mg/dl the 95% limits of confidence could be reduced to +/- 22 h. Considering the duration of terminal episode (less than 6 h) the precision was +/- 20 h. In this way our modified procedure is suitable for every case with the resulting precision of estimation being determined only by the duration of the terminal episode and urea concentration.     

A diagnostic program for estimating the time of death using microcalculators MK-61 and B3-34

The programme design is based on the process of changes in dead body temperature. Specific features of the process of changes in temperature values of a dead body are characterized by a parameter which involves process sample obtained by temperature measurements in diagnostical area of a cadaver at the accident scene during 1 hour. Programme provides for estimation of postmortem interval within the first 60 h after death occurrence. Diagnostical deviations don't exceed +/- 3% as compared to the real time of death.     

Estimation of postmortem interval using an electric impedance spectroscopy technique: A preliminary study

The objective of this study was to develop a rapid method for the estimation of postmortem interval (PMI) using electric impedance spectroscopy. Postmortem rat spleens were studied at 10 °C, 20 °C, and 30 °C; The results obtained demonstrated that postmortem interval negatively correlated with the absolute value of Im Z^// (capacitive reactance component) in electrical impedance. This suggests that electric impedance spectroscopy may be a sensitive tool to determine the postmortem interval.     

Postmortem changes in electrical resistance of the gastric wall during the early postmortem period in rats.

A simple and reliable technique was employed for measurement of (dc) electrical resistance of the gastric wall of rats. Tissue resistance decreased linearly (r = -0.87; P less than 0.001) from 66.1 +/- 12.1 kOhm/cm2 immediately following death to 23.3 +/- 3.5 kOhm/cm2 at a postmortem interval of 24 h. These changes are believed to reflect progressive postmortem changes in the physical dimensions of the intercellular space and/or changes in electrical conductivity of the intercellular/extracellular fluids.     

大鼠死后肌肉总腺苷酸及腺苷酸能荷的时序性变化

目的 测定大鼠死后不同时间双后肢肌肉嘌呤腺苷酸[三磷酸腺苷(adenosine triphosphate,ATP)、二磷酸腺苷(adenosine diphosphate,ADP)、一磷酸腺苷(adenosine monophosphate,AMP)]含量,计算总腺苷酸(total adenine nucleotide...     

单细胞凝胶电泳分析死后小鼠骨骼肌细胞核DNA降解

目的研究小鼠死后骨骼肌细胞核DNA降解与死亡时间的关系。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内不同时间点骨骼肌细胞核DNA电泳形状的8项参数值,所得数据进行统计学分析。结果在个体死亡72h内,“彗星”的尾DNA含量比例、尾长、尾矩、O live矩、尾面积数值随时间的延长而增大;而“彗星”的头半径,头DNA含量比例和头面积数值则随时间的延长而减小。经对每个参数的测量值进行多项式运算,获得DNA降解趋势的二项式回归方程(P<0.001)和多元回归方程(P<0.0001),且均具有极显著性意义。结论在死后一定时间内,小鼠骨骼肌组织核DNA降解随死后经过时间的变化而呈一定规律性变化,DNA降解与死亡时间之间呈线性相关。     

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。     

Evaluation of the Postmortem Glucose and Glycogen Levels in Hepatic,Renal, Muscle,and Brain Tissues: Is It Possible to Estimate Postmortem Interval Using These Parameters?

The aim of our study was to investigate the postmortem levels of glucose and glycogen in hepatic, renal, muscle, and brain tissues and then examine the changes in those levels that could be useful for estimating postmortem interval. We established an animal model. Seventy female BALB/c albino mice were used in this study. After being sacrificed, the mice were randomly divided into six groups according to time elapsed since death (Group 1: 0 h; Group 2: 12 h; Group 3: 24 h; Group 4: 36 h; Group 5: 48 h; and Group 6: 60 h). Glucose levels were significantly different between groups for all tissues studied. Slope of the change per unit time was higher for the hepatic glucose levels. Based on these results, it is possible to estimate postmortem interval using postmortem glucose levels in hepatic tissue. Tissue‐specific assessment may contribute valuable information to postmortem interval studies.