大鼠死后组织细胞DNA含量变化与死亡时间的相关性研究

目的应用流式细胞术研究大鼠死后组织细胞DNA含量变化与死亡时间的相关性。方法SD大鼠断颈处死后于不同时间段取心、肝、脾、肾器官组织,经胰蛋白酶消化等处理后制成单细胞悬液,应用流式细胞术,在620nm波长处检测各组不同器官组织细胞DNA含量,观察其变化规律。结果大鼠各器官组织细胞DNA含量随死亡时间延长均呈下降趋势。其中以脾组织细胞DNA含量变化趋势与死亡时间最具相关性,肝、肾次之,而心最差;死后48h,各器官组织细胞仅存微量完整的细胞核DNA。结论机体死亡后,各器官组织细胞核DNA含量随死亡时间的延长逐渐减少,具有一定的变化规律,可应用组织细胞DNA含量变化来推断死亡时间。     

人脾细胞核几何参数变化与早期死亡时间的相关性研究

目的运用图像分析技术探讨人脾脏细胞核几何参数变化与死亡时间的关系。方法选31例已知死亡时间的人离体脾组织,在死后36h内每h细胞学涂片、Feulgen-Vans染色,对人脾细胞核的异形指数等5个几何参数进行图像分析。结果脾脏细胞核异形指数在死后5～36h呈上升趋势,r=0.983,线性回归方程y=11.334x-33.339,面积、等效直径、平均直径、周长均与死亡时间无明显的相关性。结论异形指数能较客观地反映人脾细胞核DNA降解后的离散分布状况,与死亡时间有明显相关性,可能是推断早期准确死亡时间的较好形态学指标。     

家兔死后红细胞内钾钠离子含量与死亡时间的关系

研究了40只家兔死后不同时间心血红细胞内钾钠离子含量变化及红细胞膜Na+－K+－ATP酶活性。发现红细胞内钾离子含量随死亡时间增加呈线性下降（r=-0．829,P＜0．025）。在死后0－48小时,红细胞内钾离子含量与死亡时间显著相关。红细胞膜Na+－K+－ATP酶活性在死后48小时无显著变化。     

Measuring Family Violence: The Conceptualization and Utilization of Prevalence and Incidence Rates

The present study argues for a standard conceptualization of prevalence and incidence in family violence research. Reviewing several definitions of both prevalence and incidence in the family violence literature, we identify important inconsistencies in conceptualizations. The use of time frame to distinguish incidence and prevalence seems to have been a main thrust of the conceptual confusion. A gold standard conceptualization is proposed that sees prevalence as the extent to which violent behavior is distributed in the population and incidence as the amount of violent behavior that occurs among those in the population who experience violence. A discussion of rates calculated with other conceptualizations illustrates the need for standardization as well as the utility of the conceptualization in the present study. The calculation of prevalence and incidence rates is exemplified with respect to interpartner violence using Statistics Canada's Violence Against Women Survey (VAWS). Using duration as an independent variable, we also illustrate how the choice of incidence or prevalence rates may affect the operation of risk markers. Given the need for standardization, the relative ease with which this can be accomplished, and the knowledge that research in this area will be conducted well into the future, we conclude with a plea for a standard use of prevalence and incidence among family violence scholars.     

Current state and progress of research on forensic biomechanics in China

Forensic biomechanics gradually has become a significant component of forensic science. Forensic biomechanics is evidence-based science that applies biomechanical principles and methods to forensic practice, which has constituted one of the most potential research areas. In this review, we introduce how finite element techniques can be used to simulate forensic cases, how injury criteria and injury scales can be used to describe injury severity, and how tests of postmortem human subjects and dummy can be used to provide essential validation data. This review also describes research progress and new applications of forensic biomechanics in China.

Key points

• The review shows the main research progress and new applications of forensic biomechanics in China.
• The review introduces eight cases about the application of forensic biomechanics, including the multiple rigid body reconstruction, the finite element applications, study of mechanical properties, traffic crash reconstruction based on multiple techniques and analysis of morphomechanical mechanism about blood dispersal.
• Though forensic biomechanics has a great advantage for the evaluation of injury mechanisms, it still has some uncertainties owing to the uniqueness of the human anatomy, the complexity of biological materials, and the uncertainty of injury-causing circumstances.

     

Aqueous Fluid as a Viable Substitute for Vitreous Fluid in Postmortem Chemistry Analysis

Vitreous fluid sampling for postmortem chemistry analysis is discouraged in pediatric forensic cases involving head trauma due to the risk of introducing retinal artifacts. Aqueous fluid is physically separated from the posterior chamber of the eye, and therefore, unlikely to produce vitreal artifact when sampled. Analysis of aqueous fluid is therefore proposed as a substitute for vitreous. Vitreous and aqueous fluid was sampled concurrently from 28 pediatric and 55 adult decedents, and sodium (Na), potassium (K), chloride (Cl), urea nitrogen (UN), creatinine (Cr), and glucose (Glc) concentrations were compared. Significant correlation existed between all analytes regardless of age or postmortem interval, and linear regression equations were derived. Aqueous concentrations were generally higher than vitreous for Na, K, and Cr and were marginally lower for Cl, UN, and Glc. Assuming vitreous fluid as a standard for correlating postmortem chemistry to antemortem serum values, aqueous may be a viable substitute for vitreous when expected differences are considered.     

Urea,Uric Acid,and Creatinine in Postmortem Blood,Vitreous Humor,and Synovial Fluid: A Comparative and Correlation Study,

Urea, uric acid, and creatinine have been demonstrated to be relatively stable in postmortem blood (BL), thus being useful for diagnostic purposes. However, no studies have explored their levels in BL, vitreous humor (VH), and synovial fluid (SF) concurrently. Therefore, we measured and compared their levels in these fluids. We also determined the effects of various factors on their levels. The results indicated that BL urea, uric acid, and creatinine levels were significantly higher than VH and SF levels. VH and SF urea levels and SF creatinine levels had a strong correlation with BL urea and creatinine levels, respectively. BL creatinine levels were higher in men than in women. BL and SF creatinine levels were negatively correlated with age. SF uric acid and BL, VH, and SF creatinine levels exhibited a positive correlation with weight. Only VH creatinine levels were positively correlated with body mass index. None of urea, uric acid, and creatinine levels were correlated with postmortem interval.     

A Pilot Study Comparing Postmortem and Antemortem CT for the Identification of Unknowns: Could a Forensic Pathologist Do It?

Forensic pathologists are commonly tasked with identifying human remains. Although DNA analysis remains the gold standard in identification, time and cost make it particularly prohibitive. Radiological examination, more specifically analog imaging, is more cost-effective and has been widely used in the medical examiner setting as a means of identification. In the United States, CT imaging is a fairly new imaging modality in the forensic setting, but in more recent years, offices are acquiring CT scans or collaborating with local hospitals to utilize the technology. To broaden the spectrum of potential identifying characteristics, we collected 20 cases with antemortem and postmortem CT images. The results were qualitatively assessed by a forensic pathologist and a nonmedically trained intern, and all cases were correctly identified. This study demonstrates that identification of human remains using visual comparison could be performed with ease by a forensic pathologist with limited CT experience.     

Evaluation of Agonal Cardiac Function for Sudden Cardiac Death in Forensic Medicine with Postmortem Brain Natriuretic Peptide (BNP) and NT-proBNP: A Meta-analysis

Sudden cardiac death (SCD) is an unexpected death caused by a sudden loss of cardiac function, which is currently a global public health problem. Evaluation of the agonal cardiac function of the deceased is a quite important task for the diagnosis of SCD in forensic medicine. Brain natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are currently considered as significant biomarkers for the diagnosis of heart failure in both clinical and forensic practices. To investigate the postmortem evaluation roles of postmortem BNP and NT-proBNP levels for SCD, the present study meta-analyzed eight related studies from Embase, Cochrane Library, PubMed, China Biomedical Literature Database, China National Knowledge Infrastructure, and Wanfang Data. Newcastle–Ottawa Quality Assessment Scale was used to assess the quality of the included literature, and the meta-analysis was performed by RevMan 5.3.5 software. Postmortem NT-proBNP in pericardial fluid showed higher levels in the SCD group than that of the non-SCD group with the weighted mean difference = 3665.74, 95% confidence interval: 1812.89–5518.59, and p = 0.0001. However, postmortem levels of BNP in pericardial fluid and NT-proBNP in serum revealed no statistical difference between SCD and non-SCD subjects. The results of present meta-analysis demonstrated that postmortem NT-proBNP in the pericardial fluid could be used as an ancillary indicator for evaluation of agonal cardiac function in forensic medicine.     

Artifacts Caused by Leaf-Cutting Ants of the Genus Atta (Hymenoptera: Formicidae): Postmortem Bite Injuries and the Tearing of Clothes

Ants are one of the first insects to find an exposed cadaver and can be present during all stages of decomposition. Although these organisms are not commonly used in postmortem interval estimates, they are to be taken into account on criminal investigations involving human corpses, since they can leave bite marks that can be mistaken for antemortem or perimortem injuries, which could be misleading when ascertaining the occurrence of abuse or physical altercation during a crime. A few studies report the action of ants on human cadavers and even though leaf-cutting ants of the genus Atta are frequently encountered in succession studies that use animal carcasses, there are no records of these fungus-growing species on human corpses. Atta is a genus restricted to the New World, ranging from northern Argentina to southern United States and acts as one of the most conspicuous neotropical herbivores. In this study, we report three cases of violent death that illustrate the impact of ants, especially those of the genus Atta, in a forensic setting. We compare the patterns displayed by postmortem bite injuries caused by leaf-cutter ants and other common species with less robust mandibles. We also present the capability of Atta ants to create artifacts by cutting victim’s clothes in a crime scene, contributing to the knowledge of ant-mediated confounding factors in crime scene investigation.