3-Methoxytyramine in the putamen as a gauge of the postmortem interval

The armamentarium of the forensic thanatologist includes the examiner's subjective assessment of bodily changes together with comprehensive evaluation of environmental and associated factors to estimate the postmortem interval (PMI). Of the various objective means, postmortem accumulation of potassium in vitreous humor is a widely used gauge. In view of the considerable variability inherent in these techniques, an additional marker with greater accuracy would be a welcome supplement to these indices. We have developed a method of estimating PMI from the level of 3-methoxytyramine (3-MT) in the dorsal putamen of the brain. The supernatant of a sample of putamen, sonicated in 6 volumes (weight/volume) of 0.1 M perchloric acid and centrifuged at 51 000 times gravity for 10 min, was analyzed for 3-MT using high-pressure liquid chromatography with electrochemical detection. The change of 3-MT in the putamen is linearly related to the PMI (range: 5.5 to 60 h), irrespective of patient age (1 to 84 years). This observation is attributable to several factors, including high substrate (dopamine) concentration, preservation of catechol-O-methyl transferase activity, and an inactivation of monoamine oxidase activity, as a result of a decrease in tissue pO2.     

玻璃体液化学成分规律性改变与死亡时间推断的研究进展

死亡时间（postmortem interval．PMI）的准确推断是法医尸体检验工作中的难题之一,PMI推断对刑事案件的侦察和审判具有重要的意义。人死亡后不同时间眼玻璃体液化学成分的规律性变化,如钾、镁、氨、尿素氮、肌酐和尿酸、次黄嘌呤、乳酸的含量逐渐升高,而钙、钠、酶类、葡萄糖、维生素C的含量逐渐降低,有助于比较准确地进行PMI推断。本文对其在法医学领域的研究进展进行综述。     

家兔眼玻璃体液21例元素含量PMI关系的研究

目的寻找一种精确推定PMI的方法。方法应用电感耦合等离子体质谱(ICP-MS),系统研究了家兔死后96h内眼玻璃体液21种元素含量与PMI的相关性。结果眼玻璃体液Co、Mo、Cd、Sb、I、Pb、Bi、Li共8种元素与PMI无关。K、Mg、Fe、P、Na、Al、Ca、Ti、Ni、Cu、Zn、Sr、Ba共13种元素含量与PMI有关。结论眼玻璃体液K、Mg、Fe、P、Na、Al、Ca、Ti、Ni、Cu、Zn、Sr、Ba共13种元素与PMI有关。为研究人尸体眼玻璃体液元素与PMI的关系奠定了选择指标的基础。     

家兔急性有机磷中毒死后玻璃体液化学成分的变化趋势

目的 探讨家兔急性有机磷中毒死后不同时间眼玻璃体液化学成分的变化。方法用5％敌百虫制作家兔急性有机磷中毒动物模型,在死后0～72h内不同时间点,采用留置微量重复取样法吸取眼玻璃体液,以全自动生化分析仪测量眼玻璃体液中钾、镁、磷、钙、钠、氯浓度的变化,统计数据进行二项式回归方程拟合分析。结果家兔急性有机磷中毒死后72h眼玻璃体液中钾、镁、磷随PMI延长而逐渐升高,舻分别为0．9818、0．9700、0．9458,与PMI相关性好,其中30h内镁的相关性更好;钙、钠随PMI延长呈降低趋势,砰分别为0．7124、0．7355,相关性较差;氯表现不稳定掣仅为0．0869。结论家兔急性有机磷中毒死后玻璃体液中钾、镁、磷、钙、钠等离子浓度随PMI延长而改变,72h内总体衡量,钾与PMI最具有相关关系。     

A new biochemical method for estimation of postmortem time.

Hypoxanthine (Hx) is formed by hypoxic degradation of adenosine monophosphate (AMP) and might be elevated due to antemortem hypoxia. However, it also increases after cessation of the life processes. Until now measurements of potassium in corpus vitreous humor have been used by forensic pathologists to determine postmortem time. In this study the influence of postmortem time and temperature on vitreous humor Hx and potassium levels were compared. Repeated sampling of vitreous humor was performed in 87 subjects with known time of death and diagnosis. The bodies were kept at either 5 degrees C, 10 degrees C, 15 degrees C or 23 degrees C. Hx was measured by means of HPLC and potassium by flame photometry. In 19 subjects from whom samples were obtained within 1.5 h after death, the normal level of Hx could be estimated to be 7.6 mumol/l and that of potassium to be 5.8 mmol/l. The spread of the potassium levels measured shortly after death was much greater than for the corresponding Hx levels. In the four temperature groups the Hx level increased 4.2, 5.1, 6.2 and 8.8 mumol/l per h, respectively, whereas the corresponding figures for potassium were 0.17, 0.20, 0.25 and 0.30 mmol/l per h. The vitreous humor concentration of both Hx and potassium increases fairly linearly after death. The slopes are steeper with increasing temperature. Since the scatter of the levels is greater for potassium than for Hx, the latter parameter seems to be better suited for the determination of time of death in cases without antemortem hypoxia, especially during the first 24 h.     

PMICALC: An R code-based software for estimating post-mortem interval (PMI) compatible with Windows,Mac and Linux operating systems

In legal medicine the correct determination of the time of death is of utmost importance. Recent advances in estimating post-mortem interval (PMI) have made use of vitreous humour chemistry in conjunction with Linear Regression, but the results are questionable. In this paper we present PMICALC, an R code-based freeware package which estimates PMI in cadavers of recent death by measuring the concentrations of potassium ([K+]), hypoxanthine ([Hx]) and urea ([U]) in the vitreous humor using two different regression models: Additive Models (AM) and Support Vector Machine (SVM), which offer more flexibility than the previously used Linear Regression. The results from both models are better than those published to date and can give numerical expression of PMI with confidence intervals and graphic support within 20 min. The program also takes into account the cause of death.     

Vitreous humor biochemical constituents: evaluation of between-eye differences

The present study was conducted to investigate the differences in the vitreous humor biochemical concentrations for vitreous electrolytes and calcium in the same pair of eyes at identical postmortem interval (PMI). The vitreous humor samples were collected independently in both eyes from 48 autopsies (PMI range, 4.5-84.3 hours) with documented time of death. The samples were analyzed for potassium, sodium, chloride, and calcium using a Beckman Coulter LX20 Automated Analyzer based on ion-selective electrode methodology. There were no statistically significant between-eye differences at identical postmortem interval. A significantly high correlation was observed between paired potassium concentrations of both the eyes. A highly significant linear correlation was observed between the individual eye and mean potassium concentrations of both the eyes with postmortem interval. The observed differences were not significantly correlated with postmortem interval. The results demonstrated that the between-eye differences for vitreous electrolytes and calcium are insignificant. Therefore, the utility of vitreous biochemistry, particularly potassium in postmortem interval estimation and other forensic applications, cannot be questioned solely on the basis of these differences.     

Research Progress on Postmortem Interval Estimation by Vitreous HumorCSCD

Postmortem interval (PMI)estimation is one of the most challenging problems in the field of forensic science. Vitreous humor is a hotspot which has been used for PMI estimation and postmortem chemical analysis in forensic pathology. In order to provide novel perspectives for the future research of PMI estimation using vitreous humor, the comparison between vitreous humor with other common body fluids, the effect of temperature on vitreous humor, vitreous humor detection method and data fitting method have been reviewed in this paper. © 2018 by the Editorial Department of Journal of Forensic Medicine.     

家兔死后玻璃体液电导率变化与死亡时间的关系

目的探讨家兔死后玻璃体液电导率变化与死亡时间的相关性。方法采用电导分析法检测家兔30℃下死后48h内及20℃下死后120h内玻璃体液电导率变化。结果30℃和20℃下家兔死后玻璃体液电导率随死亡时间延长而持续升高。经统计分析得到抛物线型二项式回归方程,其相关系数分别为0.970和0.983,两式P〈0.01。结论家兔死后玻璃体液电导率升高程度可以作为推断死亡时间的参考指标。     

家兔死后眼玻璃体液镁，铁含量与PMI关系的研究

目的寻找一种精确推定PMI的方法。方法应用电感耦合等离子体质谱(ICP-MS),检测家兔死后96h内眼玻璃体液镁、铁元素含量,探讨其与PMI的相关性。结果家兔死后0～48h眼玻璃体液镁元素含量与PMI显著相关,6～48h铁元素含量与PMI显著相关,其二项式回归方程分别为y=0.0738x2+0.6997x+11.45(R2=0.9119)、y=0.0411x2-0.3148x+1.4113(R2=0.9594)。结论家兔死后眼玻璃体液Mg、Fe含量变化可作为推定48h内PMI的参考指标之一。     

Is there recent progress in the estimation of the postmortem interval by means of thanatochemistry?

Numerous methods have been proposed in the last 60 years for the determination of the time since death by chemical means. Many of them were reviewed by Schleyer in his monograph on the determination of the time since death by means of thanatochemistry about 40 years ago and none of these early methods has gained any practical value since they do not meet the demands in practice (being precise, reliable, giving an immediate result). While the earlier studies were mainly carried out on blood and cerebrospinal fluid (CSF) since the late 60s most investigations have been performed on vitreous humor (VH). This is mainly due to the fact that vitreous humor is topographically isolated and well protected, and thus, autolytic changes proceed slower compared to blood and CSF. The most studied parameter in VH is potassium and even nowadays reports on the postmortem rise of vitreous potassium are published, proposing new analytical methods or statistical evaluations. Chemical parameters studied for the determination of the time since death have to be differentiated according to the underlying process (catabolism, metabolic processes, pure autolysis and diffusion, putrefactive changes). In the present paper, recent studies on thanatochemistry are discussed regarding the underlying process, the analytical methods (for instance H magnetic resonance spectroscopy (1H MR spectroscopy), immunohistochemistry), the studied fluid compartment, the statistical evaluation and the precision of death time estimation. The value of chemical methods for the determination of the time since death is up to now very limited. This is supported by the fact that field studies on the reliability and precision of death time estimation by chemical means are still scarce in the literature.     

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。     

利用房水钾离子浓度推断死亡时间的实验研究

目的探讨利用房水中钾离子浓度进行死亡时间推断的可行性。方法30只家兔随机分为10组,以空气栓塞法处死后,于不同的死亡时间点分别采集房水和玻璃体;用Vitros 950干式自动生化仪对所有样本中的K+、Na+、Ca2+三种离子进行浓度测定;用SPSS统计软件对测定数据进行回归分析。结果房水中钾离子浓度变化与死亡时间呈高度相关,对应的回归方程为:PMI=1.572-0.597×[K+]+0.107×[K+]2-0.002×[K+]3。其相关系数(R2=0.95)明显高于同批样本的玻璃体钾离子浓度与死亡时间的相关系数(R2=0.5)。房水、玻璃体液的Na+、Ca2+浓度与死亡时间的相关性不明显。结论利用房水钾离子浓度推断死亡时间可获得较好的准确度。     

Vitreous Humor: Biochemical Constituents in Estimation of Postmortem Interval*,†

Abstract: Analysis of biochemical constituents of the vitreous humor can be useful in determining the postmortem interval as there is proportionate postmortem rise of potassium and fall in sodium concentration. We studied 120 autopsy cases to determine the utility of potassium, sodium, calcium, and chloride levels, and sodium/potassium ratio in estimating the postmortem interval. There was a linear relationship between vitreous potassium concentration and postmortem interval, whereas an inverse relationship between vitreous sodium/potassium ratio and postmortem interval was noted. Other factors like age, sex, cause of death, season of death, and refrigeration of sample did not influence the vitreous humor potassium values. Using the statistical tools, a new formula was derived to determine the postmortem interval based on the potassium concentration and a review of previous literature is presented. Hence, the findings of this study supported a central role of vitreous humor biochemistry in many postmortem forensic and pathological evaluations.     

Vitreous humor chemistry: the use of potassium concentration for the prediction of the postmortem interval

Upon review of the literature, extensive disagreement was found as to the usefulness of vitreous humor potassium concentration as a predictor of the postmortem interval (PMI). A pilot study of 1427 cases was performed to address this problem. The requisite statistical analysis for the prediction of PMI is inverse prediction. The 95% inverse prediction interval was found to be approximately +/- 20 h. The linear regression equation for the data was y = 0.238 chi + 6.342, with a coefficient of determination (r2) of 0.374. This r2 value means that 62.6% of the variation of potassium is unaccounted for by the variation in PMI. Further studies are required to attribute this unaccounted variation to quantifiable factors. This would narrow the inverse prediction interval and enable vitreous potassium to be a useful aid in the prediction of PMI.     

家兔死后眼玻璃体液锌、镍含量与 PMI关系的研究

目的寻找一种精确推定PMI的方法。方法应用电感耦合等离子体质谱（ICP－MS）,检测了家兔死后96小时内眼玻璃体液锌、镍元素含量,探讨其与PMI的相关性。结果家兔死后24h内眼玻璃体液锌、镍元素含量与PMI显著相关,可作为推定早期PMI的参考指标,其二项式回归方程分别为y=0.1404x2－1.3351x＋3.8298（R2=0.9202）、y=0.0043x2－0.0596x＋0.2665（R2=0.9103）。结论家兔眼玻璃体液中Zn、Ni元素含量变化是推定早期PMI的参考指标之一。     

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...     

Postmortem biochemical examination of synovial fluid--a preliminary study

Vitreous humor chemistry is used for postmortem analysis since serum values of many components are thought to be reflected in vitreous humor and to be stable for a prolonged postmortem interval (pmi). A similar isolated compartment to vitreous humor is synovial fluid which up to now was hardly used for postmortem chemistry.The aim of the present examination was to compare the values of various analytes in both fluid compartments to get first hints for the reliability of the examination of synovial fluid. Therefore, in 74 cases of sudden death both fluids were taken and analysed for natrium, potassium, calcium, chloride, urea, creatinine, and glucose. The results show that the examination of synovial fluid as compared to vitreous humor is a reliable method to get hints on the premortal metabolic status since most analytes are stable postmortem. The range of all values is comparable in both fluids. The time course of glucose concentrations and, much more important, potassium concentrations is nearly similar. If no vitreous humor is available synovial fluid may be used with all precautions in diagnosis known from vitreous humor.     

家兔玻璃体液2种酶活性变化与死亡时间的相关性

目的探讨死后家兔玻璃体液胆碱脂酶(CHE)和谷草转氨酶(GOT)活性与死后经过时间(PM I)的相关性。方法应用光度法检测在25~30℃和10~15℃下死后即刻至54h之间玻璃体液CHE和GOT活性。结果死后即刻至54h之间,ChE、GOT活性分别由约850U/L、220U/L逐步降解趋于零。死后6h内,两种酶活性降解存在平台期。统计分析,得出相应的单元和多元回归方程,相关系数或决定系数均在0.896以上,P<0.01。结论两种酶活性的降解规律可作为较为客观的推断PM I的参考指标。     

双眼交替微量取样检测兔玻璃体液钾镁离子浓度推测死亡时间

目的研究死后眼玻璃体液钾镁离子浓度变化及其与死亡时间的关系。方法取健康家兔处死,死后不同时间于双眼玻璃体液交替微量取样,采用全自动生化分析仪检测样本中[K+]、[Mg2+],对所得数据进行统计学处理。结果死后12~120h,家兔玻璃体液中[K+]由11.01mmol/L上升至32.97mmol/L,[Mg2+]1.12mmol/L上升至2.22mmol/L,两种离子浓度与PMI进行回归分析自变量为[K+]的二次多项式回归方程为y=0.1756x2-3.3188x+29.804(R2=0.9868);自变量为[Mg2+]的二次多项式回归方程为y=-46.916x2+248.01x-213.81(R2=0.9340);自变量为[K+]和[Mg2+]的二次多项式回归方程为y=-17.55-4.82[K+]+0.20[K+]2+75.77[Mg2+]-19.47[Mg2+](R2=0.9881)。用[K+]的方程推测PMI,当[K+]<26.0mmol/L(PMI<60h)时,平均偏离时间为2.7~9.4h,当[K+]>28mmol/L(PMI>72h)时,平均偏离时间>15h;用[Mg2+]的方程推测PMI,平均偏离时间几乎均在10h以上;用二元方程推测PMI,平均偏离时间较前两者小。结论死后眼玻璃体液[K+]、[Mg2+]随时间延长而升高,且浓度变化与时间呈强相关性。但从实际运用角度考虑,R2<0.98,或平均预测偏离时间过大的回归方程,不宜用于PMI推测;应用多指标建立多元回归方程是提高推测PMI准确性的可行方法。