Postmortem behavior of the rheobase

Own investigations on the postmortem rise of muscular threshold were conducted on 20 bodies with exactly known time of death. Muscular contraction was objectified using a sensitive force transducer. The muscle was excitated using rectangular impulses of 1 second duration of a current intensity which produces a force of muscular contraction of 2.5 mN. These excitations were continued over the postmortem interval until a current intensity of 80 mN doesn't cause a contraction of 2.5 mN any more. Investigations were mainly performed at the thenar muscles. There is a linear relationship between ln of muscular threshold (current intensity) and the time since death (r = 0.965). For any case the linear regression line between ln of muscular threshold and time since death was calculated. With mean values for slope and intercept the time of death was calculated for each measured threshold. Extrapolation of the time since death with mean values also for the slope reveals a much more precise estimation of the time since death than an extrapolation with an individual slope as proposed by Joachim and Feldmann (1980). The method was proved on a random sample of 8 practical cases. The real time since death was always within the 95%-limits of confidence of the extrapolated time since death.     

傅里叶变换红外光谱技术在死亡时间推断中的运用

死亡时间(postmortem interval,PMI)推断是命案现场首先要解决的重要问题之一,因此法医学者运用了大量的技术和统计学方法试图精确推断PMI.由于PMI推断受到外部、内部、死亡前和死亡后等多种因素影响,既往多种方法均存在局限性.傅里叶变换红外(Fourier transform infrared,FTIR)光谱技术已应用于蛋白质、核酸、碳水化合物的纯品物质研究上,近年来也被广泛用于研究复杂的细胞和组织.功能强大的计算机软件可以对光谱变换、平滑、基线校正、归一化等进行处理,使FTIR光谱仪对样本的定量研究成为可能,并从分析化学领域推广到生物学和临床医学研究.本文综述了FTIR光谱原理及其在生物医学中的应用,并着重阐述死后尸体组织的FTIR光谱学变化及在PMI推断中的应用价值.     

Precision of estimating the time since death by vitreous potassium--comparison of two different equations

The precision of death time estimation by vitreous potassium using two different formulas [1-3] is compared on an independent random sample of 100 cases. The very flat slope in Sturner's equation is the reason for a systematic overestimation of the time since death with much wider 95%-limits of confidence compared to the results using an own equation with a steeper slope of vitreous potassium.     

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.     

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 (<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.     

芬太尼中毒死亡大白兔体内分布研究

目的建立芬太尼中毒致死的动物模型,探讨芬太尼在致死大白兔体内的分布规律。方法用6只雄性大白兔按5.4mg/kg(2LD50)经耳缘静脉推注芬太尼注射液,大白兔死后迅速解剖并提取心、肝、脾、肺、肾、脑、肌肉、睾丸、胃、心血、周围血、胆汁和尿液,用正己烷∶乙醇(20∶1)萃取,利用UPLC-MSn法检测各组织和体液中芬太尼含量,使用SPSS15.0进行方差分析,均数两两比较的SNK法进行统计分析。检验水准为α=0.05。结果实验大白兔给药后1min出现颈项强直、四肢抽搐等中毒症状,平均4.7min因呼吸抑制而死亡。死后肺内芬太尼含量最高,其次是肾和心,而尿液中含量较低。结论本实验的结果与相关案例报道基本吻合,提示肺、肾和心脏是芬太尼中毒案件鉴定的理想检材,芬太尼在致死大白兔体内的分布规律可为相关案件的鉴定提供一定的依据。     

尸检样本乙醇分析结果的解释策略

由于死后各种复杂的人为现象的存在,使得建立死后血液酒精含量(BAC)和死亡时醉酒状态之间的关系十分困难。在日常检案中必须考虑细菌污染、发酵是否引起死后乙醇再合成,死亡时胃中未被吸收的乙醇是否向周围组织以及血中扩散等问题。本文总结了关于死后乙醇分析及结果解释相关问题的研究文献,旨在为从事法医毒物学乙醇分析的同行在调查此类案件时提供良好的开端。     

Interpreting results of ethanol analysis in postmortem specimens: a review of the literature

We searched the scientific literature for articles dealing with postmortem aspects of ethanol and problems associated with making a correct interpretation of the results. A person's blood-alcohol concentration (BAC) and state of inebriation at the time of death is not always easy to establish owing to various postmortem artifacts. The possibility of alcohol being produced in the body after death, e.g. via microbial contamination and fermentation is a recurring issue in routine casework. If ethanol remains unabsorbed in the stomach at the time of death, this raises the possibility of continued local diffusion into surrounding tissues and central blood after death. Skull trauma often renders a person unconscious for several hours before death, during which time the BAC continues to decrease owing to metabolism in the liver. Under these circumstances blood from an intracerebral or subdural clot is a useful specimen for determination of ethanol. Bodies recovered from water are particular problematic to deal with owing to possible dilution of body fluids, decomposition, and enhanced risk of microbial synthesis of ethanol. The relationship between blood and urine-ethanol concentrations has been extensively investigated in autopsy specimens and the urine/blood concentration ratio might give a clue about the stage of alcohol absorption and distribution at the time of death. Owing to extensive abdominal trauma in aviation disasters (e.g. rupture of the viscera), interpretation of BAC in autopsy specimens from the pilot and crew is highly contentious and great care is needed to reach valid conclusions. Vitreous humor is strongly recommended as a body fluid for determination of ethanol in postmortem toxicology to help establish whether the deceased had consumed ethanol before death. Less common autopsy specimens submitted for analysis include bile, bone marrow, brain, testicle, muscle tissue, liver, synovial and cerebrospinal fluids. Some investigators recommend measuring the water content of autopsy blood and if necessary correcting the concentration of ethanol to a mean value of 80% w/w, which corresponds to fresh whole blood. Alcoholics often die at home with zero or low BAC and nothing more remarkable at autopsy than a fatty liver. Increasing evidence suggests that such deaths might be caused by a pronounced ketoacidosis. Recent research has focused on developing various biochemical tests or markers of postmortem synthesis of ethanol. These include the urinary metabolites of serotonin and non-oxidative metabolites of ethanol, such as ethyl glucuronide, phosphatidylethanol and fatty acid ethyl esters. This literature review will hopefully be a good starting point for those who are contemplating a fresh investigation into some aspect of postmortem alcohol analysis and toxicology.     

The rise and rise of fentanyl in postmortem casework

Forensic toxicology laboratories are navigating a period of time with increasing drug overdose deaths, an opioid epidemic, the impact of the COVID-19 pandemic, and the illicit drug market flooded with novel psychoactive substances. In New York City, the Department of Forensic Toxicology has experienced a 56% increase in postmortem casework in the past decade with fentanyl detected in 80% of all overdose deaths. Over a period of 2.5 years, 15,638 postmortem cases were tested for the presence of fentanyl and fentanyl analogs using liquid-chromatography tandem mass spectrometry (LCMSMS). Fentanyl was detected in approximately one third of cases and of these 4447 cases with femoral blood. A twofold increase in cases with high concentrations of fentanyl (>100 ng/mL) was observed between 2021 and 2022. The minor metabolite and precursor chemical, 4-ANPP (4-anilino-N-phenethylpiperidine) may help differentiate between illicit and licit fentanyl. 4-ANPP blood concentrations were <10 ng/mL in 98% of the cases and the 4-ANPP:fentanyl ratio was <0.67 for 99.1% of blood specimens. Only six cases had 4-ANPP concentrations higher than the corresponding fentanyl blood concentration. This study also highlights, the changing fentanyl analogs found in postmortem cases since 2016 in NYC with the emergence of fluorofentanyl initially identified in 2020 and continuing to dominate in comparison with the prevalence of other analogs, many of which are no longer detected in casework. The detection of one of the latest drugs to be mixed with fentanyl, namely xylazine, has also increased in prevalence by 36.7% in 2022 compared with 2021.     

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.     

Postmortem tricyclic antidepressant concentrations. Lethal versus nonlethal levels

Evidence has accumulated that postmortem release of tissue-bound tricyclic antidepressants (TCAs) may cause falsely elevated postmortem blood levels, thus rendering it more difficult to determine if the cause of death was an overdose. This study, a review of 24 TCA-related deaths, is aimed at defining the practical significance of such a problem and providing a workable approach to interpreting postmortem TCA levels. Deaths clearly due to TCA drugs were compared with deaths that were not caused by TCA drugs, but in which the decedent's postmortem blood tested positive for TCA medications. There is little evidence that postmortem elevations in blood TCA levels cause frequent problems in differentiating lethal from nonlethal levels (overdose from nonoverdose cases). The data suggest that using a heart blood level of 0.100 mg/dl as an indicator of lethality is practical at the present time and poses little likelihood of error. Isolated cases suggest that postmortem TCA increases can occur; further work is needed in this area to clarify more fully the significance and frequency of such cases. At present, it seems prudent to utilize peripheral blood samples for TCA testing on autopsy material, if a conservative estimate of TCA concentration is desired, possibly augmented by liver TCA levels and parent-metabolite ratios if money, facilities, and time permit.     

Evaluation of postmortem serum calcium and magnesium levels in relation to the causes of death in forensic autopsy

There appears to be very poor investigation of postmortem serum calcium (Ca) and magnesium (Mg) for diagnostic evidence to determine the cause of death. The aim of the present study was a comprehensive analysis of the serum levels in relation to the causes of death in routine casework. Autopsy cases (total, n=360; 5-48 h postmortem), including blunt injury (n=76), sharp injury (n=29), asphyxiation (n=42), drownings (n=28: freshwater, n=11; saltwater, n=17), fire fatalities (n=79), methamphetamine (MA) poisoning (n=8), delayed death from traumas (n=37), and acute myocardial infarction/ischemia (AMI, n=61), were examined. In total cases, there was no significant postmortem time-dependent rise in serum Ca and Mg. Both Ca and Mg levels in the heart and peripheral blood were significantly higher in saltwater drowning compared with those of the other groups. In addition, a significant elevation in the Ca level was observed in freshwater drowning and fire fatalities, and in the Mg level in fatal MA intoxication and asphyxiation. Topographic analyses suggested a rise in serum Ca and Mg due to aspirated saltwater in drowning, that in serum Ca in freshwater drowning and fire fatalities of peripheral skeletal muscle origin and that in serum Mg in MA fatality and asphyxiation of myocardial and/or peripheral origin. These markers may be useful especially for diagnosis and differentiation of salt- and freshwater drownings and may be also helpful to determine the causes of death involving skeletal muscle damage, including burns and MA intoxication.     

Estimation of the time since death

The main principle of the determination of the time since death is the calculation of a measurable date along a time-dependent curve back to the start point. Characteristics of the curve (e.g. the slope) and the start point are influenced by internal and external, antemortem and postmortem conditions. These influencing factors have to be taken into consideration quantitatively in order to improve the precision of death time estimation. It does not make any sense to study the postmortem time course of any analyte without considering influencing factors and giving statistical parameters of the variability. Comparison of different methods requires an investigation of the same postmortem interval. For practical purposes, it must be concluded that the amount of literature on estimating the time since death has a reverse correlation with its importance in practice.     

Hypothermia-related Deaths: A 10-year Retrospective Study of Two Major Metropolitan Cities in the United States*

Hypothermia-related deaths affect vulnerable populations and are preventable. They account for the vast majority of weather-related deaths in the United States. The postmortem diagnosis of hypothermia can be challenging, as there are no pathognomonic signs. The electronic databases of the New York City Office of Chief Medical Examiner and Harris County Institute of Forensic Sciences were searched for all fatalities where the primary cause of death included hypothermia, between January 2009 and July 2019. There were 139 hypothermia deaths in New York City (NYC) with an average annualized rate of 1.7 per million. During this same time, there were 50 hypothermia deaths in Houston with an average annualized rate of 2.4 per million. Males were more likely to die of hypothermia compared to females in both cities. The rate ratio (RR) in NYC was 3.55 (95% CI 2.40, 5.25), while the RR in Houston was 2.83 (95% CI 1.50, 5.32). Age- and sex-specific standardized hypothermia mortality rates were 18.2 (95% CI 15.1, 21.2) per million in NYC and 30.1 (95% CI 21.7, 38.6) per million in Houston. The comparative hypothermia death ratio was 1.66 (95% CI 1.19, 2.30), indicating hypothermia mortality in Houston was 66% higher than in NYC. There was no correlation between zip code poverty rates and hypothermia-related deaths. The most consistent autopsy finding was Wischnewski spots (56.6%), and ethanol was the most common toxicological finding (36.5%). Local agencies can use this data to target these higher-risk populations and offer appropriate interventions to try to prevent these deaths.     

Evaluation and usefulness of reverse dot blot DNA-PolyMarker typing in forensic case work

Experiments were performed to evaluate the Amplitype PolyMarker DNA typing system for application to forensic casework. DNA extraction using chelex was compared with phenol-chloroform extraction for various biological materials including postmortem blood, blood samples used for alcohol quantification, fresh urine, envelopes and cigarette butts. Different amounts of genomic DNA were amplified to test the sensitivity of the Amplitype PM. Mixed samples of two different bloods were typed to determine the dilution at which mixtures could be detected. Different storage conditions were evaluated using urine samples. Postmortem blood samples were typed during 4 months to determine the effects of natural degradation. A population sample of 105 unrelated individuals from South-West Switzerland was analyzed and the genotype frequencies were compared with those reported by others. Finally, practical usefulness of the Amplitype PM system is illustrated by analysing casework samples. The results of this validation proved the great usefulness and sensitivity of the Amplitype PM system using the appropriate extraction and typing method. However, mixed samples had to be interpreted with caution owing to the possibility of non-specific alleles with stored material such as urine and postmortem blood.     

Tissue-specific differences in mRNA quantification of glucose transporter 1 and vascular endothelial growth factor with special regard to death investigations of fatal injuries

Glucose transporter 1 (GLUT1) and vascular endothelial growth factor (VEGF) have been established as being responsible for cellular adaptation to oxygen deficiency in tissue ischemia and hypoxia mediated by hypoxia-inducible factor 1. We hypothesized that mRNA quantification of these factors in autopsy tissue specimens could have diagnostic significance for investigating the pathology of death, especially after injury. Various cases (total, n=119; less than 48h postmortem) were examined, including fatal blunt injury (n=71) and sharp instrument injury (n=18), as well as asphyxia (strangulation/hanging, n=12) and acute myocardial infarction/ischemia (n=18) as controls. Quantification of mRNA by TaqMan real-time RT-PCR and immunostaining were performed for GLUT1 and VEGF in lung, kidney, and skeletal muscle specimens. The postmortem interval showed no significant influence on the relative quantification of mRNA during the early postmortem period. Characteristic results were found in blunt injury cases: both GLUT1 and VEGF mRNAs decreased in the lung but increased in the skeletal muscle depending on survival time. In the kidney, subacute deaths showed higher GLUT1 mRNA levels compared with acute deaths from blunt injury, but no significant change was found for VEGF mRNA. Immunohistochemistry showed visually predominant GLUT1 immunoreactivity in the renal cortex for cases with a longer survival time, coincident with the results at the mRNA level. Tissue-specific differences in mRNA quantification of GLUT1 and VEGF shed light on tissue ischemia/hypoxia and subsequent tissue-dependent pathophysiological changes leading to death after injury.     

The Achilles tendon as a DNA source for STR typing of highly decayed corpses

Forensic criminal casework often involves DNA profiling of human postmortem tissues, whereas degradational processes can affect PCR-based Short Tandem Repeat (STR) analysis. Degradation of DNA is observed to vary among different tissues and with time. Therefore, the stability of DNA in Achilles tendon samples is compared to that in muscle and kidney specimens with a variety of postmortem histories. Tissue samples from 28 autopsy cases, including 15 decomposed corpses and a control group of 13 nondecayed corpses were analysed. DNA was isolated using the All-tissue DNA Kit (GEN-IAL, Troisdorf, Germany), quantified by spectrophotometric measurement, amplified by the multiplex PCR genRES MPX-2 (Serac, Bad Homburg, Germany), and analysed on the ABI PRISM 310 Genetic Analyzer (Applied Biosystems, Darmstadt, Germany). Quantitative analysis of nondecomposed tissues revealed that the recovery of DNA was highest in kidney followed by muscle, whereas Achilles tendon tissue was the poorest source of isolated DNA. Only small amounts of DNA were present in both kidney and muscle samples from decomposed corpses. However, from decayed Achilles tendon samples twice as much DNA as from nondecayed samples could be isolated on average. These results suggest DNA to be better protected in Achilles tendons. Moreover, postmortem changes in Achilles tendons may even improve DNA isolation.     

Interleukin-6 and C-reactive protein serum levels in sepsis-related fatalities during the early postmortem period

Postmortem interleukin-6 (IL-6) and C-reactive protein (CRP) serum levels were investigated prospectively in sepsis-related fatalities and non-septic fatalities by using a linear regression model. At least three blood samples were collected between 0.3 and 139 h postmortem from sepsis-related fatalities (n=8) and non-septic fatalities (n=16). In addition, one antemortem blood sample was collected shortly before death from the septic patients. Antemortem and postmortem IL-6 and CRP levels were highly elevated in all individuals included in the sepsis group. An excessive postmortem increase of IL-6 serum levels associated with progressive time after death was observed in five out of the eight septic patients. Both, IL-6 and CRP serum concentrations seem to be suitable biochemical postmortem markers of sepsis. The determination of IL-6 serum levels above 1500 pg/ml in peripheral venous blood obtained in the early postmortem interval can be considered as a diagnostic hint towards an underlying septic condition. A more precise postmortem discrimination between sepsis and non-septic underlying causes of death is provided by the postmortem measurement of serum CRP in peripheral venous blood: on condition that at least two postmortem CRP values have been determined at different time points postmortem, the CRP level of a deceased at the time of death can be calculated by using linear regression analysis. When assessing postmortem IL-6 and CRP concentrations as biochemical postmortem markers of sepsis, various clinical conditions, such as a preceding trauma or burn injury going along with elevated IL-6 and/or CRP levels prior to death as a result of the systemic inflammatory response syndrome (SIRS) should be taken into consideration, thus adding relevant information for the practical interpretation of the results.     

Estimating time of death from measurement of the electrical excitability of skeletal muscle.

Post-mortem contraction was measured using sensitive force transducers inserted into human muscle. The muscle was stimulated using rectangular impulses of 1 sec duration and known current intensity. After some time, a noticeable change of the muscular contraction occurred, from a two-peak to a one-peak shape. The maximum force of the muscular contraction using a stable current intensity decreased with time since death, but relaxation time increased. The decrease of the maximum force and the increase of the relaxation time were used as criteria for extrapolating the time since death in a random sample of 50 bodies. The calculated 95% limits of confidence were 2.85 h (decrease of the maximum force) and 2.7 h (increase of relaxation time) up to 13 hours post mortem. The calculated 95% limits of confidence were checked on an independent sample of 21 bodies and proved to be reliable.     

Drugs in postmortem adipose tissues: evidence of antemortem deposition

INTRODUCTION: Drug concentration measured in postmortem adipose tissue may or may not reflect antemortem concentration. To examine the possibility of whether the presence of basic drugs in adipose tissue is the result of postmortem change, we examined: tissues with and without livor mortis, concentration gradients within the adipose layer, and the stability of drug concentrations during the postmortem period. CASE REPORTS: Five drug-related deaths with case histories and analytical data are presented. Adipose tissues with and without livor mortis from the thigh area of the same decedent were analyzed for cocaine. The cocaine concentration of the tissue exhibiting 4+ livor was equivalent to the concentration observed in tissue without livor. Analyses of cross sections of adipose tissues containing cocaine and methamphetamine disclosed that drug concentrations were equally distributed throughout the layer, from just beneath the dermis to directly above the muscle. When morphine and temazepam concentrations were measured in adipose tissues collected from similar sites, but at different times, from the same cadaver, they remained essentially the same over 3 days (approximately 80 h). CONCLUSIONS: Since concentrations were the same in areas with and without livor mortis, the possibility of redistribution into adipose from blood or vascular channels is eliminated. The absence of a concentration gradient within the adipose layer rules out diffusion or permeation from muscle into the adipose layer, and the failure of morphine or temazepam concentration to change over time indicates that drugs in the adipose tissue are stable during the postmortem interval. Our findings support the notion that drugs identified in postmortem adipose tissue are there because of antemortem deposition and not because of any postmortem change or event.