Importance of information in forensic toxicology.

Information in forensic toxicology plays a very important role. The forensic pathologist usually seeks toxicologic analyses on basis of the information available at the time of the medicolegal autopsy. Such information may be obtained from different sources: hospitals, authorities, relatives, friends, or neighbors of the deceased and, obviously, macroscopic findings at the time of the autopsy. In order to evaluate the relative importance of these different sources of information, the authors have studied, retrospectively, results of 580 postmortem examinations performed at the Institute of Legal Medicine of Lisbon, wherein toxicologic analyses had been requested. These cases pertain to the years 1987 and 1988, but do not include alcohol determination in the blood in cases of traffic accidents. In 274 (47.4%) of the 580 cases, there were positive findings while in the remaining 306 (52.6%) findings were negative. In cases with positive findings, circumstances and factors, which may have influenced the pathologist's decision to request toxicologic analysis, are discussed. In more than half the cases, hospital information was the decisive factor, while in approximately 25% of the cases, autopsy findings were the justification. In contrast, it is worth mentioning that in approximately 45% of the cases with analytical negative results, requests were made, in cases of blank autopsies, for toxicologic analyses in order to exclude the possibility of poisoning. It is interesting to note that in the same proportion requests were justified on grounds of hospital information. Some of the factors that may explain this apparent discrepancy are discussed. Finally, the relevance of background information is emphasized at the level of the interpretation of analytical results, whether positive or negative.(ABSTRACT TRUNCATED AT 250 WORDS)     

A comparison of Demirjian's four dental development methods for forensic age assessment

The aim of this study was to determine the comparative accuracy of Demirjian's four dental development methods for forensic age estimation in the Western Australian population. A sample comprising 143 individuals aged 4.6 to 14.5 years were assessed using Demirjian's four methods for dental development (original 7-tooth: M(2), M(1), PM(2), PM(1), C, I(2), and I(1); revised 7-tooth: M(2), M(1), PM(2), PM(1), C, I(2), and I(1); 4-tooth: M(2), M(1), PM(2), and PM(1); and an alternate 4-tooth: M(2), PM(2), PM(1), and I(1)). When comparing all four methods, the 4-tooth method overestimated age in both males and females by 0.04 and 0.25 years, respectively. The original 7-tooth was least accurate for males, while the original 7-tooth, the revised 7-tooth, and the alternate 4-tooth were unsuitable for females. Therefore, we recommend the 4-tooth method to be used for forensic age estimation in Western Australian males and females, as it has the lowest overall mean deviation and the highest accuracy.     

Application of forensic toxicology to the problem of domestic violence.

The role of the forensic toxicologist in helping to determine causes of death or in aiding in the resolution of "driving under the influence" or similar cases is well known and clearly understood. Less clearly defined is the position of the forensic toxicologist vis-à-vis other socially significant problems. However, as the 21st century approaches, it is worth considering how forensic toxicology can help in unraveling some of these problems. The problem of violence between intimates--that is, domestic violence--is a social problem in which it has been long felt that alcohol has played a part. Until now, though, no carefully controlled toxicological studies have been conducted to substantiate this or to determine whether other drug use is associated with domestic violence. At the San Francisco Medical Examiner's Office, toxicological data from both the victim and the suspect in 20 cases of domestic violence that ended in homicide have been gathered. It was found that alcohol or other drugs or a combination of these factors was invariably present in the suspect, the victim, or both. The implications of these results and how they can be used to develop a toxicological strategy to help reduce the most serious consequences of domestic violence are presented.     

Comparing two analytical methods: minimal standards in forensic toxicology derived from information theory

Frequently, new instrumentation and techniques are being applied to casework without an adequate knowledge of how this new technology compares to acceptable analytical procedures. Information theory provides a mathematical method to estimate the identification power of various analytical procedures and predicts if the new method produces a better or poorer confidence in the analysis than an accepted method. This paper makes comparisons based on relative informational power and discusses methods to make those estimates. With the procedures outlined in this paper, an analyst can estimate if a novel technique has the opportunity of reaching the accepted analytical methodology and, if necessary, identify places where the greatest improvement can be made to reach this equilivalence. Even though relative information theory can dismiss some proposed techniques before any analysis starts, it cannot verify if a given technique is adequate for a particular task. For that purpose, a complete procedural verification must be undertaken.     

近十年法医毒物分析和法医毒理学研究热点统计分析

借助Bicomb 2.0软件及SPSS 19.0软件对近十年国内外法医毒物分析和法医毒理学的研究热点进行分析,结果表明国内研究热点可以分为5类:分类1为毒品和精神活性物质的提取方法和样品稳定性研究;分类2为镇静催眠药的代谢和死后分布研究;分类3为农药的快速检测方法开发;分类4为分析方法的完善和标准化研究;分类5为新型毒物γ-羟基丁酸和合成大麻素的检测方法研究。国际研究热点分为6类:分类1为传统精神活性物质、乙醇和样品稳定性的研究;分类2为芬太尼的分析研究;分类3为氰化物的检测和毒理学研究;分类4为新型精神活性物质的检测图库建立和分析方法开发;分类5为镇静催眠药的研究;分类6为丁烷及其引起的猝死案例的研究。同时,对近十年国际合作法医毒物学研究进行了网络可视化分析。     

The use of buffered celite columns in drug extraction techniques and their proposed application in forensic toxicology

The recoveries of acidic, basic, and neutral drugs through buffered celite columns are reported. The methods are rapid, simple, clean, and efficient, especially with compounds having a high volatility.     

Sensitive and specific multiresidue methods for the determination of pesticides of various classes in clinical and forensic toxicology

Original and sensitive multiresidue methods are presented for the detection and quantitation, in human biological matrices, of 61 pesticides of toxicological significance in human. These methods involved rapid solid-phase extraction using new polymeric support (HLB and MCX) OASIS cartridges. Gas chromatography-mass spectrometry (GC-MS) was used for volatile (organophosphate, organochlorine, phtalimide, uracil) pesticides and liquid chromatography-ionspray-mass spectrometry (LC-MS) for thermolabile and polar pesticides (carbamates, benzimidazoles). Acquisition was performed in the selected ion monitoring (SIM) mode. Extraction recovery varied owing to the nature of pesticides, but was satisfactory for all. Limits of detection (LODs) and limits of quantitation (LOQs) ranged, respectively, from 2.5 to 20 and from 5 to 50ng/ml. An excellent linearity was observed from LOQs up to 1000ng/ml for all the pesticides studied. The proposed procedures yielded reproducible results with good inter-assay accuracy and precision. A few cases of intoxication are presented to demonstrate the diagnostic interest of these methods: in two cases were determined lethal concentrations of endosulfan and carbofuran; in four other cases, the procedures helped diagnose intoxication with, respectively, parathion-ethyl, the association of bromacil and strychnine, bifenthrin and aldicarb.     

Estimating the uncertainty associated with Widmark's equation as commonly applied in forensic toxicology

No computation is performed more frequently by forensic toxicologists than that involving Widmark's equation. The equation is employed to estimate either the number of drinks consumed or the corresponding blood or breath alcohol concentration. Despite the wide use of Widmark's equation, rarely is an uncertainty estimate also provided. Estimates from Widmark's equation involve at least seven uncertain random variables. Uncertainty estimates are presented that rely on methods of general error propagation compared to a method developed by Widmark. Assuming reasonable variable and uncertainty estimates, the error propagation method yielded for N=10.4 drinks, a combined uncertainty (standard deviation) of 1.3 drinks (CV=12.3%). Similarly, estimating the blood alcohol concentration yielded for 0.120 g/100 ml, an uncertainty of 0.0255 g/100 ml (CV=21.2%). Widmark's uncertainty method yielded 1.6 drinks (CV=15.4%). The derivation of Widmark's uncertainty estimate is also presented, showing that he considered only rho and beta to be uncertain. Widmark estimates for the number of drinks should include a 2CV estimate of approximately 25% while the blood alcohol concentration estimate should include a 2CV estimate of approximately 42%. Including valid estimates of uncertainty should enhance the legal admissibility and confidence for Widmark estimations.     

Extraction procedures for some common drugs in clinical and forensic toxicology.

The results of four extraction systems for 86 drugs are reported. These systems were investigated with the view to obtaining a rapid, reliable, and efficient extraction technique in clinical and forensic toxicology.     

Alcohol screening with the Alcoscan test strip in forensic praxis

The Alcoscan test strip was applied as an assay for the screening of alcohol in vitreous humor and urine samples in autopsy cases and in saliva from drunken drivers. The method gives instant and reliable semi-quantitative information on the presence of alcohol and is valuable when considering the necessity of chemical sampling especially during autopsy.     

Difficulties of sex determination from forensic bone degraded DNA: A comparison of three methods

Sex determination is of paramount importance in forensic anthropology. Numerous anthropological methods have been described, including visual assessments and various measurements of bones. Nevertheless, whatever the method used, the percentage of correct classification of a single bone usually varies between 80% and 95%, due to significant intra- and inter-population variations, and sometimes variations coming from secular trends. DNA is increasingly used in a forensic context. But forensic DNA extraction from bone raises several issues, because the samples are very often badly altered and/or in very small quantity. Nuclear DNA is difficult to get from degraded samples, according to low copy number, at least in comparison with mitochondrial DNA. In a forensic context (as in a paeleoanthropological context) DNA sex determination is usually complicated by the weak amount of DNA, the degraded nature of nucleic acids, the presence of enzymatic inhibitors in DNA extracts, the possible faint amplification of Y band and the risk of contamination during either excavation or manipulation of samples.The aim of this work was to compare three methods of DNA sex determination from bones: procedure #1 using a single PCR amplification, procedure #2 using a double PCR amplification, and procedure #3 adding bleaching for decontamination of the bone, instead of simply rubbing the bone. These processes were applied to samples of bones (49 samples coming from 39 individuals) that were in various states of post mortem alteration.The main results are the following. (i) No DNA could be extracted from three skulls (parietal bones, mastoid process), the compact bone of one rib, and the diaphysis of one femur; (ii) there was a contamination in three skulls; and (iii) the Y band did not appear in two male cases, with one of the three procedures (male tibia, procedure #2) and with procedures #2 and #3 (male femur).This study emphasises the main issue while working with altered bones: the impossibility to extract DNA in some cases, and, worth of all, the contamination of the sample or the faint amplification of Y band which leads to a wrong sex answer. Multiple and significant precautions have to be taken to avoid such difficulties.     

MDMA心肌毒性的法医毒理学研究进展

3,4-亚甲基二氧基甲基苯丙胺(MDMA)是近年来在全世界,特别是亚洲地区公共娱乐场所流行性滥用的"摇头丸"的主要药物成分。MDMA主要作用于人体神经系统从而表现出各种神经系统症状。目前的实验研究发现,MDMA对人体多个系统具有毒性作用,其中对心血管系统的毒性损害作用较为显著。本文就近年来针对MDMA心肌毒性机制的法医毒理学研究进展进行综述,为进一步深入研究提供理论信息。     

人骨骼及牙齿DNA提取方法的比较和优化

目的人骨骼和牙齿DNA提取方法的比较和优化。方法收集18份不同个体的长骨、30颗磨牙和同一个体2根股骨、8颗磨牙。利用TissueLyser-Ⅱ组织破碎仪和PreFiler Express BTA^TM法医DNA提取试剂盒（BTA法）,应用Automate Express^TM自动化法医DNA提取系统提取DNA,进行STR分型,与脱钙法进行比较,并进行实验条件优化。结果用TissueLyser-Ⅱ结合BTA法,约2.5h即可完成骨骼和牙齿的DNA提取,分型成功率分别为94.4%和96.7%。与脱钙法比较,两种方法获得DNA质量浓度和检出率比较接近（P〈0.05）,但BTA法在操作过程方面更具优势。最佳样本量为100mg,消化时间为2h。结论采用TissueLyser-Ⅱ组织破碎仪结合BTA法对骨骼和牙齿进行DNA提取和分型检验,能满足实际检案的要求,可在法医学实践中选择使用。     

A simple automated instrument for DNA extraction in forensic casework

The Qiagen BioRobot EZ1 is a small, rapid, and reliable automated DNA extraction instrument capable of extracting DNA from up to six samples in as few as 20 min using magnetic bead technology. The San Diego Police Department Crime Laboratory has validated the BioRobot EZ1 for the DNA extraction of evidence and reference samples in forensic casework. The BioRobot EZ1 was evaluated for use on a variety of different evidence sample types including blood, saliva, and semen evidence. The performance of the BioRobot EZ1 with regard to DNA recovery and potential cross-contamination was also assessed. DNA yields obtained with the BioRobot EZ1 were comparable to those from organic extraction. The BioRobot EZ1 was effective at removing PCR inhibitors, which often co-purify with DNA in organic extractions. The incorporation of the BioRobot EZ1 into forensic casework has streamlined the DNA analysis process by reducing the need for labor-intensive phenol-chloroform extractions.     

分子印迹技术在法庭毒物分析中的研究进展

分子印迹聚合物具有预识别性、高度选择性、实用性,已广泛应用在样本前处理中,可以选择性的识别复杂基质中低浓度目标物,提高检测灵敏度。本文旨在综述和探讨分子印迹技术的原理和在法庭科学领域毒物分析应用中的研究进展。     

A pharmacokinetic study of ethyl glucuronide in blood and urine: applications to forensic toxicology

This pharmacokinetic study investigated the kinetics of ethanol and its metabolite ethyl glucuronide (EtG) in blood and urine during the whole time course of absorption and elimination. There are few previous studies on the kinetics of EtG in blood, and we wanted to evaluate whether such knowledge could yield valuable information regarding the time of ethanol ingestion in forensic cases, such as, for instance, drunk driving. Ten male volunteers consumed ethanol at a fixed dose of 0.5 g/kg body weight in a fasted state. Blood samples were collected for 14 h and urine samples were collected for 45-50 h after the start of drinking. EtG reached its maximum concentration (C(max)) in blood after a median of 4 h (range 3.5-5), a median of 3 h (range 2-4.5) after C(max) for ethanol. The ethanol-to-EtG ratios in blood (ethanol in g/L, EtG in mg/L) were >1 only for the first median 3.5 h (range 2.5-3.5) after drinking. EtG elimination occurred with a median half-life of 2.2 h (range 1.7-3.1 h), and the renal clearance was 8.32 L/h (median, range 5.25-20.86). The concentrations of EtG were always much higher in urine than in blood. The total amount of EtG excreted in the urine was median 30 mg (range 21.5-39.7), representing 0.017% (median, range 0.013-0.022) of the ethanol given, on a molar basis. The information from the present study may be a valuable supplement to determine the time of ethanol ingestion. For this purpose, two subsequent increasing EtG values and a high ethanol-to-EtG ratio in blood would support information of recent drinking.     

磁珠DNA自动提取系统在法医检验中的应用

磁珠DNA自动提取系统是将磁珠分离技术与DNA自动提取工作站结合运用,以达到高效提取DNA的目的,它具有操作时间短、准确性高、检材用量少等特点,特别适用于大批量生物检材的快速提取,是目前主流的DNA自动化提取方法。本文对磁珠DNA自动提取系统的基本组成、工作原理、操作流程及其在法医检验领域中的应用等进行了综述,并对该系统的发展前景进行了展望。     

A density gradient technique for use in forensic soil analysis

A high-density aqueous salt solution for the preparation of density gradients is presented. It has been used successfully by the authors in forensic soil analysis. It has a density range that allows for the separation of a soil specimen's heavy mineral components. It has no odor or toxic fumes, which eliminates the need to use a hood during preparation, and is far superior to the organic liquids normally used to prepare density gradients. This liquid should cause many forensic scientists to reexamine their attitudes towards using density gradients in forensic soil casework.     

DNA提取自动化工作站在法医学领域的应用

自动化工作站是指运用生化技术对生物性检材进行批量处理分析的全自动化工作平台,它可在短时间内批量进行移液,加样,混合等操作,特别适合用于大量生物性检材的PCR模板的制备。本文仅对DNA提取自动化工作站的基本模式、基本方法、法医学应用等进行综述,以期使该技术在法医DNA分析中得到更广泛的应用。