膝关节侧副韧带损伤MRI影像诊断的比较研究

目的研究膝关节侧副韧带损伤的MRI诊断与法医学鉴定意义。方法对经手术或临床证实的11例共13条损伤的侧副韧带与12例正常膝关节进行回顾性MRI对比研究。结果正常胫、腓侧副韧带在T1WI和T2WI上均呈扁平条状低信号结构,平均长度分别为6.8cm和5.7cm;13条侧副韧带损伤,单纯胫侧副韧带损伤6条,单纯腓侧副韧带损伤3条,两侧侧副韧带同时损伤2例4条;其中I级侧副韧带损伤5条,II级侧副韧带损伤5条;III级侧副韧带损伤3条;7例(63.6%)出现并发症,其中前交叉韧带损伤3条,后交叉韧带损伤4条,半月板损伤2个。结论MRI能清晰显示膝关节侧副韧带解剖结构,能准确诊断侧副韧带损伤并进行分级,还能发现多种并发症,对法医学鉴定有重要意义。     

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。     

恒强磁场下的大鼠肿瘤细胞凋亡和P53基因的关系

目的 探讨恒强磁场所致的Warlker-256肿瘤细胞凋亡机制。方法 以全长P53cDNA作探针,采用DNA和RNA Dot Blot及分子印迹杂交(Southern和Northern Blot)技术和免疫组织化学染色检测320只磁场处理动物和80只未经磁场处理动物肿瘤细胞P53基因扩增、重排、缺失、转录和表达。结果 在Warlker-256肿瘤细胞,P53为野生型,磁场处理和未经处理的动物均未见P53基因扩增、重排和缺失。磁场处理组P53基因转录比未经磁场处理组明显增强(P<0.01)。免疫组化显示,磁场处理组比未经磁场处理组P53表达显著增强(P<0.01)。结论 以上结果提示恒强磁场引起的荷瘤大鼠肿瘤细胞凋亡同P53基因转录和表达增强有关,表现出P53依赖性凋亡的特点。     

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.     

Identifying Fatal Head Injuries on Postmortem Computed Tomography Using Convolutional Neural Network/Deep Learning: A Feasibility Study

Postmortem computed tomography (PMCT) is a relatively recent advancement in forensic pathology practice that has been increasingly used as an ancillary investigation and screening tool. One area of clinical CT imaging that has garnered a lot of research interest recently is the area of “artificial intelligence” (AI), such as in screening and computer-assisted diagnostics. This feasibility study investigated the application of convolutional neural network, a form of deep learning AI, to PMCT head imaging in differentiating fatal head injury from controls. PMCT images of a transverse section of the head at the level of the frontal sinus from 25 cases of fatal head injury were combined with 25 nonhead-injury controls and divided into training and testing datasets. A convolutional neural network was constructed using Keras and was trained against the training data before being assessed against the testing dataset. The results of this study demonstrated an accuracy of between 70% and 92.5%, with difficulties in recognizing subarachnoid hemorrhage and in distinguishing congested vessels and prominent falx from head injury. These results are promising for potential applications as a screening tool or in computer-assisted diagnostics in the future.