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。     

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.     

Determination of calcium and magnesium in postmortem human vitreous humor as a test to ascertain the cause and time of death

The concentrations of magnesium and total calcium human vitreous humors obtained postmortem was tested. In the groups of heart disease and asphyxia a correlation between the postmortem interval and calcium or magnesium concentrations was found. There was no correlation between postmortem interval and calcium respectively magnesium in the other causes of death. It seems possible that the analysis of vitreous humor may be useful in both diagnosis and determination of postmortem interval in the cases of heart death and asphyxia.     

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.     

Postmortem increase in potassium in the vitreous humor. Which parameters are suitable as indicators of antemortem agonal electrolyte imbalance?

The relationship between a rise in the potassium concentration in the vitreous humor and the time of death has been established by several authors. Sturner (1963) and Adelson (1963) have been able to demonstrate a more precise relationship between potassium and the time of death in cases of sudden death and death occurring within 6 h as opposed to death after a chronic, lingering disease. However, the duration of the terminal episode cannot always be assessed in forensic medicine. Therefore, it would be valuable if other parameters could also be established that would indicate an agonal dysregulation of electrolytes. Our study revealed that sodium, urea, chloride, and calcium are of great value in indicating antemortem electrolyte imbalance because of their stability in the vitreous humor after death. The first results established that urea may be a suitable internal standard.     

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.     

The biochemistry of vitreous humour. A comparative study of the potassium, sodium and urate concentrations in the eyes at identical time intervals after death

Analysis of the vitreous humour from an individual's eyes collected at the same time since death showed variation between the eyes in the concentration of potassium, sodium and/or urate. This previously unreported finding would limit the use of measuring these electrolytes in determining the time of death.     

Forensic value of phenobarbital, calcium and magnesium determination in vitreous humor]

The concentrations of phenobarbital, magnesium and total calcium vitreous humor obtained postmortem from sheep receiving phenobarbital, were investigated. Phenobarbital, 20 mg/kg bw was administered i.v. Two hours later the animals were killed. The vitreous humor from one eye was obtained immediately. The vitreous human from the second eye was obtained after 3 days storage of the head at 22 degrees C. The levels of phenobarbital were determined ba EMIT, calcium and magnesium levels by complexometric titration. The results showed a significant increase of the phenobarbital and magnesium concentrations after the postmortem interval. It appears from these data that the phenobarbital and also magnesium concentrations in vitreous humor can be useful in the evaluation of the time of death approximately in phenobarbital intoxications.     

Post-mortem biochemical investigations of vitreous humor

For several decades vitreous humor has been used for post-mortem biochemical investigations with the objective of a post-mortem diagnosis of pre-existing diseases and the clarification of forensic issues, in particular the determination of the post-mortem interval. For the determination of measured concentrations in vitreous humor pre-analytic factors as well as analytical and instrumental variations have to be taken into consideration. The aim of this study was a methodical investigation of two methods of sample pre-treatment as influencing variables. The compared methods were centrifugation and treatment in the ultrasonic bath. The determined parameters were sodium, potassium, chloride, calcium, lactate, urea, glucose and creatinine. Analyses were performed photometrically or by an ion-selective electrode. For some of the analytes a dilution was necessary before analysing. Regarding to the two pre-treatment methods, significant differences in the measured concentrations were not found. The precision proved to be mostly unsatisfying and was clearly better in diluted samples than in undiluted aliquots. A comparison of the vitreous humor of the two ocular bulbs did not lead to significant differences.     

Vitreous humor sodium levels in immersion deaths

To determine whether vitreous humor sodium levels might be of use in evaluating deaths associated with immersion, samples of vitreous humor were prospectively evaluated at autopsy over a 4-year period from 2006 to 2009. There were 19 cases of saltwater immersion (age range 9-76 years; mean age 44 years; M:F, 2.8:1) and 16 freshwater immersions (age range 2-81 years; mean age 27 years; M:F, 2.2:1). In the group of saltwater drownings, vitreous humor sodium levels were elevated, ranging from 145 to 184 mM (mean = 160.2 ± 9.9 mM), and in the cases of freshwater drowning, the levels were reduced, ranging from 73 to 148 mM (mean = 129.8 ± 17 mM; p < 0.0001). Alterations in electrolyte levels may have been because of hemoconcentration or dilution from electrolyte fluxes in the lungs, or from passive diffusion during immersion. This study has demonstrated that vitreous sodium level is an easily performed test that may be a useful adjunct to the investigation of possible immersion deaths.     

Is zinc a reliable biochemical marker of chronic alcoholism in the overall context of a medico-legal autopsy?

The purpose of our investigation is to appreciate the usefulness of zinc determination in the human body with regard to the tracing of chronic alcoholism at forensic autopsies. The analysis of zinc was performed in vitreous humour and in skeletal muscle. Our results tend to prove that, in post-mortem material, zinc is not a suitable marker of chronic alcoholism. Furthermore one has to take into account the frequent contamination during collection and storage of the samples and also the post-mortem increase of zinc in the vitreous humour due to autolysis.     

Serum biochemical markers in drowning: diagnostic efficacy of Strontium and other trace elements

The aim of our study was to analyse several serum biochemical markers in order to evaluate the discriminant capacity of trace elements individually and jointly in drowning (seawater drowning and freshwater drowning) and their correlation with age, sex, postmortem interval, time in water and concentrations of the trace elements in the drowning medium. Sixty-seven cases of drowning (53 seawater drownings (SWD); 14 freshwater drownings (FWD) and 73 control cases (other asphyxias, n=44, and other causes of death, n=29) were selected according to the scene, cause and circumstances of death, together with autopsy findings. Serum strontium (Sr), magnesium (Mg), sodium (Na), chloride (Cl), calcium (Ca), iron (Fe), urea, creatinine (Cr) and cardiac Troponine T (cTn-T) were measured in the left ventricle (Lv), right ventricle (Rv) and peripheral blood. Lv-Rv differences for each marker and Sr, Mg, Na, Cl, Ca and Fe concentrations in the drowning medium were determinated. Mean concentrations of Sr, Cl and Mg in both ventricles and peripheral serum and Lv-Rv differences and Ca Lv and Na Rv were significantly higher in cases of drowning than for other causes of death. In SWD, Sr, Mg, Ca, Na and Cl were significantly higher in Lv than in Rv as a result of aspirating water. In contrast, haemodilution is evident from the significantly higher levels of Fe and urea in Rv than in Lv in cases of SWD, and from the higher Mg and Cr levels in Rv in FWD. In the case of SWD, serum levels of Sr are confirmed as the best parameter for diagnosis, although other trace elements may also be useful, such as the serum concentrations of Mg and Cl. In the case of FWD, the joint determination of Sr and other biochemical markers, especially Fe, may increase correct diagnosis.     

Post-mortem hypoxanthine levels in the vitreous humour an introductory report

Post-mortem hypoxanthine levels in vitreous humour were determined in 86 consecutive legal autopsy cases. In cases of sudden death caused by trauma or by myocardial infarction, levels ranging from 0 to 540 μmol/l were found. The mean value was about ten times higher than normal in vivo plasma levels. The hypoxanthine levels seem to be independent of time post-mortem, at least during the first 48 hours.It is known that augmentation of the hypoxanthine plasma, cerebrospinal fluid, and urine levels reflects tissue hypoxia. In the present material no elevation of hypoxanthine levels in the vitreous humour was found in cases of strangulation or suspension, while statistically significant elevation was found in cases of drug intoxication. It is concluded that this may reflect the effect of drug-induced prolonged tissue hypoxia caused by respiratory depression.     

Blood carbon monoxide and hydrogen cyanide concentrations in the fatalities of fire and non-fire associated civil aviation accidents, 1991-1998

To evaluate pathophysiological significance of post-mortem urinary myoglobin levels in determining the cause of death, we investigated 210 forensic autopsy cases, partially in comparison with serum levels. Post-mortem serum myoglobin levels were extraordinary high in most cases possibly due to post-mortem change. Urinary myoglobin levels did not correlate with the serum levels, showing possible post-mortem elevation in cases of a prolonged post-mortem period over 48h. A high (>1000 ng/ml), moderate (100-1000 ng/ml), slight (50-100 ng/ml) and not significant (<50 ng/ml) elevation of urinary myoglobin were observed in 26, 43, 31 and 110 cases, respectively. Half the highly elevated cases were those with a survival time over 24h. In cases of minor muscle injury such as head trauma, elevation of urinary myoglobin level was closely related to longer survival. In acute/subacute deaths with a post-mortem interval within 48h, a significant difference was observed in relation to the blood carboxyhemoglobin (COHb) levels of fire victims: myoglobinuria over 100 ng/ml was more frequently and markedly observed in cases with COHb below 60% than over 60%, suggesting muscle damage in fatal burns. Similar elevation was observed in heat stroke victims, and also in some cases of acute and subacute death from polytrauma, asphyxiation, drowning, electricity and spontaneous cerebral bleeding, but not in myocardial infarction. Thus, it was suggested that high post-mortem urinary myoglobin levels in acute and subacute death cases may be a possible indicator of antemortem massive skeletal muscle damage as well as exertional muscle hyperactivity or convulsive disorders associated with hypoxia.     

A promising microbiological test for the diagnosis of drowning

A number of biological and chemical tests have been developed over the years to determine whether a person was drowned. This study focuses on the potential of a microbiological test for detecting common bacterial markers of water faecal pollution such as faecal coliforms (FC) and faecal streptococci (FS) as possible indicators of drowning. A promising previous study was carried out on central and peripheral blood samples of 42 drowned victims (20 cases in saltwater and 22 cases in freshwater) and 30 not-drowned bodies. To improve the accuracy of our previous results and also in order to investigate a possible cause of a false positive due to pulmonary passive diffusion and subsequently endogenous or exogenous bacterial invasion of the blood in the post-mortem interval (PMI), the FC and FS test was applied to bodies submerged in water but died from causes other than drowning. In the present study, blood samples collected from the left ventricle (LV), right ventricle (RV), femoral artery (FA) and, femoral vein (FV) of 10 drowned victims (5 cases in freshwater and 5 cases in seawater) and 3 not-drowned individuals with bodies submerged in water for a while after death have been analysed. Preliminary results are in agreement with other reports dealing with diatoms and marine bacteria that suggest to exclude the hypothesis of a passive penetration of sufficient quantities of drowning medium into circulation after death or during the agonal period. Based on our results there is also no evidence of a relevant dissemination of endogenous micro-flora from the gastrointestinal tract affecting the FS and FC test. There are still several other factors that could influence the applicability of post-mortem FS and FC cultures for the diagnosis of drowning and they need further investigations. The present article provides only a glimpse of the potential of the FS and FC test as bacteriological method for the diagnosis of drowning.     

Analysis of carbohydrate-deficient transferrin (CDT) in vitreous humour as a forensic tool for detection of alcohol misuse

Analysis of carbohydrate-deficient transferrin concentration in vitreous humour (VH-CDT) has recently been demonstrated to be useful for diagnosis of pre-mortal alcohol misuse, but more knowledge considering possible methodological problems is warranted. In a forensic sample we examined the stability of VH-CDT during laboratory handling as well as the possible affection of time-dependent changes of total transferrin concentrations in vitreous humour (VH-Transferrin) in the dead body on VH-CDT as indicator of alcohol misuse. By use of a commercial assay designed for serum analysis (CDTect) it was possible to measure VH-CDT with high precision, and detectable amounts were found in 20 of 21 alcoholics and in two of seven controls. The compound was demonstrated to be stable in vitreous humour during laboratory handling, since the results of the first analysis were well reproducible after 4 months storage of the specimens (rs=0.86, P=0.0002). Transferrin concentrations in vitreous humour (VH-Transferrin) correlated to the estimated time since the individual last time had been alive before the forensic examination (rs=0.57, P<0.005). However, in this small sample the discriminating property of VH-CDT as indicator of alcohol misuse was not decisively affected, whether or not the variables "VH-Transferrin" and "estimated time since the individual last time had been alive" were considered in a multivariate logistic regression analysis (minor change in the beta-coefficient from 0.57 to 0.52, P=0.086). We conclude that CDT is stable in vitreous humour during proper laboratory handling and that detection of VH-CDT is primarily a marker of alcohol misuse before death. However, the results of this study do not exclude that time-dependent changes of VH-Transferrin, possibly affecting VH-CDT, may occur in the dead body. VH-CDT analysis should thus, at present, be restricted to cases with rather short post-mortal time interval.     

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。     

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.     

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.     

Post-mortem examination prior to cremation--an instrument to verify the quality of medical post-mortems and uncover non-natural deaths?

The external post-mortem examination, its deficient quality and possible causes have been the subject of numerous political and professional discussions. The external post-mortem examination is the basis for the decision whether further criminal investigations are required to clarify the cause of death. It is thus an essential instrument to ensure legal certainty. Before cremation, a second external post-mortem examination is performed by a public medical officer to make sure that errors of the first post-mortem are corrected. In the present study, cases were retrospectively analyzed in which a forensic autopsy had been ordered on the basis of the results of the post-mortem examination performed before cremation. The entries on the death certificate regarding the manner and cause of death were compared with the autopsy results. Between 1998 and 2007, 387 autopsies were ordered after external examination before cremation. In 55 cases (14.2%), the autopsy revealed a non-natural death, although a natural death had been attested on the death certificate. In descending order, a wrong manner of death was attested by clinicians, general practitioners and emergency physicians. With regard to the place where the first external post-mortem had been performed the lowest error rate was seen in nursing homes. Concerning the cause of death, discrepancies between the first post-mortem and autopsy were found in 59.4% of the cases. In this respect, general practitioners and clinicians were ranking first, whereas in nursing homes the cause of death was wrongly assessed in over 70% of cases. At present, the medical post-mortem does not meet the required quality standards, especially with regard to legal certainty. Determination of the cause of death on the basis of the external post-mortem examination is a challenging task even for the experienced medical examiner. As to the categorization of the manner of death it has to be stated that non-natural deaths are often not recognized or that the possibility to certify a death as unclear is not sufficiently used. As a result, it seems important to demand intensive, qualified, additional training in external post-mortem examinations for physicians.