Nondestructive Methods for Recovery of Biological Material from Human Teeth for DNA Extraction

The extraction of DNA from human skeletal remains applied to forensic, and evolutionary studies do not exclude risks, which are to be evaluated when working with unique specimens that could be damaged or even destroyed. In the present study were evaluated several nondestructive methods for recovering DNA instead of the most currently used pulverization method. Three different procedures to access inside the dental pieces (occlusal perforation, cervical perforation, and cervical cut) have been compared with the aim of recovering as many cell remains as possible to carry out a DNA extraction. Given the DNA quantitation results, a method was proposed that consists of a cervical cut to facilitate the access to the pulp cavity and a subsequent filing of the root canals down to the apex of the dental root. This methodology allows the recovery of both mitochondrial and nuclear DNA, with the minimum deterioration for the dental pieces.     

Characteristics of Backspatter on the Firearm and Shooting Hand—An Experimental Analysis of Close‐range Gunshots

Contact and close‐range gunshot injuries can produce bloodstains on the shooting hand and weapon. In this study, backspatter was analyzed in experimental horizontal pistol shots into blood‐filled sponges. The shooting distances were set between 0 and 45 cm. With increasing shooting distance, there was a significant decrease in the degree of backspatter. Microspatter could be detected on the weapon and shooting hand up to a shooting distance of 40 cm. They were predominantly located on thumb and index finger as well as the radial dorsal aspects of the hand. Fine spray of microspatter combined with elongated droplets in the shape of exclamation marks was found at contact and 2‐cm distance shots. An angular calculation based on the shape of the bloodstains was possible up to a shooting distance of 2 cm. No bloodstains were detected beyond 45 cm.     

Assessment of Maceration Techniques Used to Remove Soft Tissue from Bone in Cut Mark Analysis

Maceration techniques employed in forensics must be effective without compromising the bone's integrity and morphology, and prevent destruction of evidence. Techniques must also be fast, safe, easily obtainable and inexpensive; not all techniques currently employed are appropriate for forensic use. To evaluate the most suitable approach, seven techniques including current and new methodologies were applied to fresh, fleshed porcine ribs exhibiting cut marks. A sample size of 30 specimens per technique was examined under scanning electron microscopy at the cut mark and the surrounding uncompromised regions; a scoring system of effectiveness was applied. The previously unpublished microwave method fared best for bone and cut mark preservation. Sodium hypochlorite destroyed cut marks, and was deemed unsuitable for forensic analysis. No single technique fulfilled all criteria; however, this study provides a benchmark for forensic anthropologists to select the most appropriate method for their situation, while maintaining the high standards required by forensic science.     

Diagnostic Value of PSA and AP Tests for the Detection of Spermatozoa in Postmortem Swabs from the Genital and Anal Region in Males

The aim of this study was to clarify whether positive results for prostate‐specific antigen (PSA) and acid phosphatase (AP) occur in postmortem swabs from the genito‐anal region in males (n = 80; 4 regions) and females (n = 20; 3 regions) and to calculate the positive predictive value (PPV) concerning the presence of spermatozoa. In male subjects, the highest incidence of positive test results was found in urethral swabs (PSA 76%, AP 71%) and the lowest frequencies appeared in perianal and rectal swabs (15–20%). Microscopic evaluation for spermatozoa was positive between 39% in urethral swabs and 1% in rectal swabs. PPV regarding positive identification of spermatozoa was 33.3% for PSA and 31.5% for AP. The combination of both tests yielded a PPV of 38.2%. In female cases, no spermatozoa were identified, and one case was PSA‐ and AP‐positive in perianal swabs. Our findings indicate that PSA and AP tests are of limited value for the postmortem detection of spermatozoa in male subjects.     

Implant Bone Integration Importance in Forensic Identification

Odontological identification consists of the comparison of antemortem dental information regarding a missing person with postmortem data from an unidentified corpse or human remains. Usually, the comparison concerns morphologic features that the operator chooses among all the visible characteristics because of inter‐individual uniqueness; for this reason, implants can be of enormous assistance. A case concerning the recovery of a burnt oral implant, connected to a bone fragment, among 2780 charred bone fragments, suspected to have belonged to a victim of homicide, is presented to demonstrate that dental implants and their site of bone integration represent a very precious element for personal forensic identification. Because of their morphological invariability in time and because of their morphologic uniqueness, they were used as evidence to associate unidentified human charred remains to a missing person where DNA analysis failed to do so. The case illustrates the fundamental contribution, not yet described in literature, given by the clinical aspects of tooth replacement with dental implants to a forensic discipline. Clinical practitioners should therefore be aware of the great importance of their work and of dental records in a forensic identification scenario.     

A Silver‐Stain Modification of Standard Histological Slide Preparation for Use in Anthropology Analyses

The traditional histology method typically employed by forensic anthropologists involves plastic embedding of undecalcified bone. The embedded sample is then cut by a diamond blade saw and ground to the required thickness of ~50–100 microns using a grinder. There are several limitations to this method: Cement lines may be blurred; depth‐of‐field artifacts may result from viewing thick sections; and medicolegal offices with limited budgets may not be able to invest in additional equipment or training for this method. A silver nitrate stain modification of the standard histology preparation technique of decalcified bone is presented. The benefits of this technique are that: Cement lines are viewed clearly; no depth‐of‐field artifacts are present; and because this is a modification of the standard technique used by histology laboratories typically employed by medicolegal offices, no additional equipment or training is required.     

微视野与视诱发电位在黄斑病变中的法医学应用

目的研究微视野仪与视诱发电位检测结果与最佳矫正视力的相关性,探索检测眼底黄斑病变者最佳矫正视力的途径。方法对62例黄斑病变者(黄斑病变组,62眼)及18例健康志愿者(对照组,36眼)进行最佳矫正视力、微视野仪及视诱发电位的检测。结果 (1)微视野仪检测示黄斑病变组视网膜平均敏感度、固视百分率均低于对照组,置信椭圆面积均大于对照组;视诱发电位检测示0.5周期/度(circle per degree,cpd)及2 cpd P100波振幅较对照组降低,潜伏期延长(P0.05)。(2)黄斑病变组最佳矫正视力与其视网膜平均敏感度、置信椭圆面积及黄斑中心2°、4°固视百分率之间呈正相关性(P0.05)。视网膜平均敏感度与P100波的振幅呈线性相关(P0.05)。(3)多元线性回归方程为y=0.053 x1+0.008 x3+3.897(y为最佳矫正视力,x1、x3分别为视网膜平均敏感度与2 cpd P100波振幅)。结论联合使用微视野仪与视诱发电位有助于判断黄斑区视网膜病变患者的客观最佳矫正视力。     

大鼠过敏性休克死后血清IgE、类胰蛋白酶的变化

目的观察大鼠过敏性休克死亡后血清IgE、类胰蛋白酶的变化规律,探讨其与死亡时间(PMI)、尸体及样本保存环境的相关性。方法建立大鼠过敏性休克死亡动物模型并分组,包括室温组、冷藏组、冷冻组、人工溶血组、血清样本保存组,并设立对照组。大鼠处死采血后,按离心后上层血清颜色进行溶血程度分级。通过ELISA法检测血清IgE、类胰蛋白酶在各组中的质量浓度。结果大鼠过敏性休克死亡后血清IgE、类胰蛋白酶水平明显高于对照组;室温、冷冻保存下血清IgE、类胰蛋白酶随PMI的不同有明显变化,冷藏保存下浓度相对稳定;随溶血程度的增加,血清IgE、类胰蛋白酶水平均呈升高趋势。样本不同温度条件下保存25 d,血清IgE、类胰蛋白酶无明显变化。结论大鼠过敏性休克死后血清IgE、类胰蛋白酶明显升高,但其水平受PMI、环境温度影响较大,尤其是室温或冷冻保存。     

MSCT鉴定高坠死亡1例分析

目的使用多层螺旋CT(multi-slice spiral computed tomography,MSCT)技术对高坠伤的损伤特征进行观察分析,并通过对高坠伤的分析和观察重建高坠过程,从而探讨MSCT在分析高坠伤案例中的应用价值。方法以真实的高坠伤案例为对象,分别运用MSCT平扫、三维重建技术对尸体进行全面检查,联合运用系统尸体解剖分析高坠伤死亡方式等特点,比较尸体解剖和MSCT在获取损伤信息方面的差异。结果MSCT扫描结合三维重建,发现全身多部位骨折以及肝破裂,尸体解剖与影像学检查结果相对应,推断死亡原因为高坠致全身多发伤。结论 MSCT在高坠伤案件致伤方式分析中可作为传统尸体解剖的补充手段。     

基于上转换发光技术的尿液中吗啡及甲基苯丙胺快速定量检测方法研究

目的利用上转换发光免疫层析技术(UPT-LF)建立一种尿液中吗啡(MOP)及甲基苯丙胺(MET)快速定量检测方法并对其进行系统评价。方法以上转换发光纳米颗粒(UCP-NPs)作为生物示踪物,竞争模式免疫层析作为检测平台,建立可对尿液中MOP及MET进行定量检测的UPT-LF,即MOP-UPT-LF、MET-UPT-LF。以MOP-UPT-LF为代表,评价UPT-LF对痕量毒品检测极限,通过系列浓度标准品测定,评价定量检测能力。根据常规检测阈值,调整MOP-UPT-LF及MET-UPT-LF检测敏感性及线性范围,并评价其定量检测能力。以LC-MS、GC-MS分别作为MOP、MET检测的金标准,以胶体金免疫层析作为对照,对执法现场收集尿样进行检测,确定UPT-LF定性检测性能。对系列浓度MOP模拟阳性样本同时进行LC-MS及MOP-UPT-LF定量检测,对系列浓度MET模拟阳性样本同时进行GC-MS及MET-UPT-LF定量检测,评价UPT-LF定量检测性能。结果在痕量检测条件下,MOP-UPT-LF敏感性可达1ng/m L,线性范围为1~5000ng/m L(r=-0.98172,P<0.0005)。在常规检测条件下,MOP-UPT-LF敏感性为50ng/m L,线性范围调整为50~3000ng/m L(r=-0.98464,P<0.0005);MET-UPT-LF敏感性为100ng/m L,线性范围为100~5000ng/m L(r=-0.99964,P<0.0005)。就定性检测而言,MOP-UPT-LF及MET-UPT-LF均较优,灵敏度及特异度均为100%,与胶体金结果一致。就定量检测而言MOP-UPT-LF及MET-UPT-LF与定量确证方法LC-MS及GC-MS无显著差异。结论本研究建立MOP-UPT-LF、MET-UPT-LF方法,在满足快筛试剂快速简便的基础上,进一步实现了现场快速定量检测,为尿液中毒品的现场快速定量检测提供了技术保障。