Single-stranded DNA as an immunohistochemical marker of neuronal damage in human brain: an analysis of autopsy material with regard to the cause of death

Single-stranded DNA (ssDNA) is a marker of apoptosis and programmed cell death, which appears prior to DNA fragmentation during delayed neuronal death. The present study investigated the immunohistochemical distribution of ssDNA in the brain to investigate apoptotic neuronal damage with regard to the cause of death in medicolegal autopsy cases (n=305). Neuronal immunopositivity for ssDNA was globally detected in the brain, independent of the age, gender of subjects and postmortem interval, and depended on the cause of death. Higher positivity was typically found in the pallidum for delayed brain injury death and fatal carbon monoxide intoxication, and in the cerebral cortex, pallidum and substantia nigra for drug intoxication. For mechanical asphyxiation, a high positivity was detected in the cerebral cortex and pallidum, while the positivity was low in the substantia nigra. The neuronal ssDNA increased during the survival period within about 24h at each site, depending on the type of brain injury, and in the substantia nigra for other blunt injuries. The neuronal positivity was usually lower for drowning and acute ischemic disease. Topographical analysis of ssDNA-positive neurons may contribute to investigating the cause of brain damage and survival period after a fatal insult.     

水通道蛋白-4研究进展及法医学意义

头颅创伤、脑卒中、脑肿瘤、缺血性脑损伤、出血性脑损伤均伴有脑水肿的发生，严重者可危及患者生命甚至造成死亡。水通道蛋白-4（Aquaporin-4）作为主要在脑组织中表达的水通道蛋白，起着调节脑内水转运的重要功能，参与脑水肿的病理生理过程，提示研究水通道蛋白-4表达水平可能为法医学外伤性脑损伤时间推断提供新的依据。     

Sudden Death Due to Primary Intraventricular Hemorrhage: Report of Two Cases

Primary intraventricular hemorrhage (PIVH) is a rare type of stroke defined as bleeding within the ventricles of the brain without any associated parenchymal hemorrhage. Here, we reported two cases of sudden death due to PIVH. One of the patients was found dead under a highway bridge without witnesses, and the other patient was hospitalized with hemorrhage in the ventricular system, as revealed by a head computed tomography scan. In these two patients, autopsy and macroscopic examination only showed hemorrhages in the ventricular system without any traumatic brain injury or other intraparenchymal hemorrhage. The sources of bleeding for both patients were ultimately confirmed as ruptured brain arteriovenous malformations located in the subventricular zone. We reported these cases to broaden our understanding of sudden death associated with PIVH, especially when caused by brain arteriovenous malformation. We also summarized the essential details of the diagnoses and available technical methods for PIVH cases.     

Evaluation of human brain damage in fatalities due to extreme environmental temperature by quantification of basic fibroblast growth factor (bFGF), glial fibrillary acidic protein (GFAP), S100β and single-stranded DNA (ssDNA) immunoreactivities

Fatalities due to extreme environmental temperatures involving hypothermia (cold exposure) and hyperthermia (heat stroke) might present with poor or nonspecific morphological pathologies, which are insufficient to establish the cause of death in forensic practice. The present study immunohistochemically investigated basic fibroblast growth factor (bFGF), glial fibrillary acidic protein (GFAP), S100β and single-stranded DNA (ssDNA) in the parietal lobe and hippocampus of the brain in fatalities from hypothermia (n=15) and hyperthermia (n=18), and compared them to those of controls (n=39), including acute death due to ischemic heart disease, mechanical asphyxiation and drowning. In addition, S100β concentration in cerebrospinal fluid (CSF) was measured. Characteristic findings in hypothermia cases were higher glial bFGF immunopositivity in the cerebral cortex and white matter, and higher S100β immunopositivity in the cerebral cortex with a lower CSF S100β concentration. Hyperthermia showed lower glial GFAP and S100β immunopositivities in the white matter, and higher neuronal ssDNA immunopositivity in the cerebral cortex and hippocampus, accompanied by high glial bFGF and S100β immunopositivities in the cerebral cortex. These findings suggest neuroprotective glial responses without marked neuronal or glial damage in fatal hypothermia, and diffuse neuronal apoptosis despite initiation of neuroprotective cortical astrocyte responses, accompanied by glial damage in the white matter, in fatal hyperthermia. These markers may be useful for evaluating brain damage and responses in fatalities due to extreme environmental temperatures.     

Intrapulmonary aquaporin-5 expression as a possible biomarker for discriminating smothering and choking from sudden cardiac death: a pilot study

The diagnosis of mechanical asphyxia as a cause of death, especially smothering and choking lacking evident injury, is one of the most difficult tasks in forensic pathology. The present study investigated the intrapulmonary expressions of aquaporins (AQPs; AQP-1 and AQP-5), as markers of water homeostasis, in forensic autopsy cases (total n=64, within 48 h postmortem) of mechanical asphyxiation due to neck compression (strangulation, n=24), including manual/ligature strangulation (n=12) and atypical hanging (n=12), smothering (n=7) and choking (n=8), compared with sudden cardiac death (n=14) and acute brain injury (n=11). Quantification of mRNA using a Taqman real-time PCR assay system demonstrated suppressed expression of AQP-5, but not AQP-1, in smothering and choking, compared with that in strangulation as well as sudden cardiac death and acute brain injury death. Immunostaining of AQP-5 was weakly detected in a linear pattern in the type I alveolar epithelial cells in smothering and choking cases, while cardiac and brain injury death showed marked positivity, and most strangulation cases had AQP-5-positive granular aggregates and fragments in intra-alveolar spaces. These observations indicate a partial difference in pulmonary molecular pathology among these causes of death, suggesting a procedure for possible discrimination of smothering and choking from sudden cardiac death.     

过敏性和冠心病猝死者心肌组织中肥大细胞类胰蛋白酶、脑利钠肽的表达

目的探讨肥大细胞类胰蛋白酶、脑利钠肽(brain natriuretic peptide,BNP)在过敏性猝死和冠心病猝死鉴别诊断中的意义。方法选取山西医科大学法医病理学教研室2010—2015年尸检案例心肌标本共30例,分为颅脑损伤致死组、过敏性猝死组、冠心病猝死组,每组各10例。采用免疫荧光染色和Western印迹法分析各组心肌组织肥大细胞类胰蛋白酶和BNP的表达。结果过敏性猝死组、冠心病猝死组心肌组织内肥大细胞类胰蛋白酶免疫荧光染色均出现阳性染色;三组间两两比较,表达差异均具有统计学意义(P0.05)。冠心病猝死组心肌组织内BNP的表达量高于过敏性猝死组、颅脑损伤致死组(P0.05),过敏性猝死组与颅脑损伤致死组之间差异无统计学意义(P0.05)。结论联合检测心肌组织内肥大细胞类胰蛋白酶、BNP有望为过敏性猝死和冠心病猝死的法医学鉴别诊断提供帮助。     

Sudden cardiac death and myocardial ischemia indicators: a comparative study of four immunohistochemical markers

The postmortem diagnosis of acute myocardial infarction represents a current challenge for forensic pathologists, particularly when death occurs within minutes to a few hours after the ischemic insult. Among the adult population the single most important cause of sudden cardiac death (SCD) is the well-known atherosclerotic coronary artery disease, commonly asymptomatic or unrecognized. The recognition of early myocardial damage using routine hematoxylin and eosin (H&E) staining is possible only if death has occurred at least 6 hours after the onset of the ischemic injury. The usefulness of immunohistochemical markers to the diagnosis of early myocardial damage has been recently suggested because most of them can be visible even serologically as early as few minutes after the beginning of the symptoms. To evaluate the usefulness of plasma and cellular antigens, their distribution patterns have been studied among a group of 18 SCD cases in which a myocardial ischemia was strongly suspected. For the present study, 4 markers have been selected on the basis of their different diagnostic potential as follows: among the plasma markers the C5b-9 and fibronectin, among the cellular markers the myoglobin and cardiac troponin. The results show that only the study of multiple markers such as those selected can provide enough evidence of myocardial ischemia and/or necrosis, supporting the final diagnosis of SCD. No single immunohistochemical staining is ideal for diagnosing early myocardial ischemia but a set of markers can improve the ability of forensic pathologists to detect ischemic areas when no macroscopic or microscopic evidence of necrosis is available. However, the interpretation of data obtained in each individual cannot be isolated from the overall assessment of the factors (cardiopulmonary resuscitation and/or agonal artifacts) that can affect the expression of each marker.     

Axonal injury in young pediatric head trauma: a comparison study of β-amyloid precursor protein (β-APP) immunohistochemical staining in traumatic and nontraumatic deaths

We tested the independent utility of β-amyloid precursor protein (β-APP) immunohistochemical staining as evidence of brain trauma in the deaths of young children. Blinded reviewers retrospectively reviewed immunostained brain tissues from homicidal deaths, age-matched control cases without evidence of trauma, as well as cases of sudden infant death syndrome (SIDS). The reviewers correctly identified five of the seven cases with documented inflicted head trauma. However, one of seven age-matched control cases and one of 10 SIDS/sudden unexplained death in infancy (SUDI) cases demonstrated staining patterns similar to those seen in cases of inflicted trauma. We discuss these cases and the circumstances surrounding them with the intent to explain the difficulties associated with immunohistological interpretation of axonal injury. Although the utility of β-APP is quite powerful if not confounded by global hypoxic-ischemic injury, ultimately, β-APP studies should be only one piece of information in the determination of cause and manner of death.     

急性心肌缺血再灌FOS免疫组织化学实验研究

探寻FOS蛋白在心肌早期缺血再灌流损伤中变化规律,为心性猝死的诊断提供新方法。利用SD大鼠建立心肌缺血再灌流损伤模型,设立正常、缺血对照组与缺血再灌组。心脏标本经HE染色及免疫级化观察。结果发现,在冷冻切片上缺血20min再灌流30min,再灌流区心肌细胞核呈阳性着色。但在石蜡切片上,缺血30min再灌流30min后,再灌流区才有心肌细胞核（37．76％±9．66％）呈弱阳性着色,再灌流60min后核呈棕褐色阳性染色,120min后开始减弱（35.36％±3.16％）。正常和单纯缺血组心肌细胞核未见有阳性反应。HE染色无明显病理改变。结果提示,SABC－FOS免疫组织化学方法最早可揭示心肌缺血20min再灌流30min的损伤,FOS蛋白在再灌流后60－120min之间可能有一个高峰表达。此法对显示实验性心肌早期缺血再灌流损伤有重要的价值。有望用于心性猝死的诊断。     

大鼠心肌急性缺血再灌注NF-кB P65和caspase-3的表达

目的观察大鼠急性心肌缺血再灌注后NF-кBP65和caspase-3在心肌中表达的规律,为心肌急性缺血早期死亡的法医学鉴定提供科学证据。方法运用免疫组化和图像分析技术观察66只SD大鼠心肌缺血再灌注后NF-кBP65和caspase-3蛋白在不同实验组中的表达规律。结果心肌缺血组缺血区域心肌组织缺血5min就可见NF-кBP65和caspase-3蛋白表达,并随缺血时间延长表达逐渐增强;而非缺血区域心肌组织仅见低水平表达或不表达;但两种蛋白(两者)并非在缺血区域心肌同一部位表达,也不是在心肌细胞内的同一部位表达;caspase-3主要在心肌细胞浆表达,而кBP65既在心肌细胞浆表达,也在心肌细胞核中表达。心肌缺血再灌注组(在)心肌缺血5min~1h内,再灌注与否并不影响这两种蛋白的表达。正常对照组未见这两种蛋白表达。结论心肌缺血再灌注时,心肌组织中有NF-кBP65和caspase-3蛋白的表达,这两种蛋白在心肌中的表达可视作诊断早期心肌缺血的参考指标。     

MicroRNA在创伤性脑损伤的研究进展

MicroRNA是一类非编码小分子RNA,可调控人类基因组中20%-30%的基因,对细胞分化、增殖和凋亡起着重要调控作用。部分microRNA在哺乳动物中枢神经系统呈高水平表达,在神经元发育、突触发生和可塑性等过程中发挥关键作用,对认知功能亦有重要影响。创伤性脑损伤所致认知障碍的鉴定是法医学领域的重点及难点问题,识别其相关的特异性microRNA及其靶基因、阐明相应的信号传导通路对明确颅脑损伤的诊断、鉴别、预后及判断致伤机制、推断死因等方面可能均具有重要价值,应是今后的研究重点。本文简介microRNA在中枢神经系统中的分布与功能,对microRNA在创伤性脑损伤中所发挥的作用以及法医学研究进展做了重点阐述。     

Detection of apoptosis in ischemic heart. Usefulness in the diagnosis of early myocardial injury

Myocardial samples of hearts with histologic findings of acute myocardial infarction (group A), sudden coronary deaths without histologic changes (group B), and chronic ischemic heart disease (group C) were analyzed to investigate the appearance of apoptosis in acute and chronic ischemic cardiac disorders. This analysis involved the morphologic detection of DNA strand breaks in myocyte nuclei by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay and the biochemical determination of DNA laddering in the myocardium using archival formalin-fixed, paraffin-embedded tissue sections of human myocardium. The authors demonstrated that apoptosis of myocardial cells could occur after ischemic myocardial cell injury. In all documented cases of acute myocardial infarction (group A), the infarcted area included extensive presence of both apoptosis and necrosis. In the tissue bordering on and away from the obviously infarcted areas, positive nuclei were intermingled with nonstained normal myocytes. The number of positive nuclei decreased with the distance from the infarction foci. In group B, myocardial samples showed focal or diffuse nuclear positivity of varying degrees for apoptosis, confirming the presence of myocardial ischemic cell death, whereas the histologic diagnosis remained inconclusive. This finding suggests that apoptosis could be used as a marker for acute ischemic injury. In group C, stained nuclei were dispersed with intermingled normal cardiomyocytes.     

原发性脑干挫伤的HE染色观察

目的观察原发性脑干挫伤的形态学特点。方法从465例致死性颅脑损伤中,检出171例有脑干挫伤病变、均于伤后10min～7d死亡者。脑干标本经福尔马林固定后,以脑干各颅神经根水平面等处切取检材,每例共8块,HE染色,光镜观察。结果 171例中有24例颅底骨折致脑干挫伤者,脑干横切面见小灶出血,其余只有在镜下方可见有组织出血、挫碎或撕裂等脑挫伤改变,以及对损伤的应激反应现象。结论原发性脑干挫伤的形态学具有一定特点,故对鉴定脑干损伤有着重要的参考价值。     

Brain injury after survived gunshot to the head: reactive alterations at sites remote from the missile track

Gunshot wounds to the brain usually lead to acute respiratory arrest or death after a brief survival period, even in cases involving only slight direct tissue damage. It can be assumed therefore that the damage extends beyond the zone of recognizable destruction and hemorrhages. To determine the true extent of the tissue injury resulting from gunshot wounds to the brain, we carried out microscopic investigations for reactive changes (emigration of leukocytes and macrophages, axonal expression of beta-amyloid precursor protein (beta-APP) in 10 cases of gunshot wound to the narrow channel of the brain with survival times >2h. Demonstration of leukocytes expressing naphthol AS-D chloroacetate esterase activity in the brain tissue at the border of the missile track established the vitality of the gunshot effect. The presence of macrophages (CD68-epitope) allowed demarcation of a 1-2mm wide necrotic zone around the permanent cavity. Within this zone and beyond, beta-APP showed an initial increase followed by a decline in the number of injured axons. Three types of beta-APP positive staining could be differentiated. In the immediate vicinity of the missile track beta-APP positive neurons were present at a distance of 2-4mm from the margin of the permanent cavity (type 1) as a result of primary injured neuronal tissue by the gunshot itself. At longer distances from the narrow channel and the permanent cavity single beta-APP positive axons or axon fragments and two additional types were found; type 2 shows a parallel, wave-like arrangement of the damaged fibers, which suggests that the injury was produced by mechanical acceleration of the brain tissue created by the energy the projectile expended within the brain; irregular aggregation of beta-APP positive axons or axon fragments within a local edema represents type 3, which may be attributed to secondary ischemia or edema.     

The expression of excitatory amino acid transporter 2 in traumatic brain injury

It is well recognized that glutamate is the major excitatory neurotransmitter, which is removed from the synaptic cleft by excitatory amino acid transporter 2 (EAAT2) located on the perisynaptic astrocytes and that neuronal death has been associated with an increased extracellular glutamate concentration. In this study, we have immunohistochemically demonstrated the expression of EAAT2 protein in the human brain after traumatic brain injury (TBI). The EAAT2 expression patterns can be divided into three types: continuous and highly extensive staining (E); continuous but sporadic staining (M); and sporadic pattern staining (S). In six of the nine short survival cases studied (1 h to 1 day), continuous and highly extensive staining for EAAT2 (E type) was observed in the ipsilateral cerebral cortex. On the other hand, we were able to demonstrate weak staining (S and M types) in 5 of the 7 long survival cases (≥1 day) and in 12 of the 14 very short survival cases (<1 h) studied. Similar findings were obtained in the contralateral cerebral cortex and also in the ipsilateral hippocampus. In addition, positive staining for glial fibrillary acidic protein was detected around the cerebral contusion, but the EAAT2-positive expression was not observed in the same region for all of the six short and long survival cases (≥1 h) after TBI. These findings clearly showed the differences in EAAT2 expression in the cerebral cortex according to the survival time and severity of cerebral contusion after TBI. Therefore, we emphasized that EAAT2 might play an important role in contributing to extracellular glutamate concentrations and secondary brain injury after TBI.     

创伤性脑损伤后生物分子标志物的研究进展

创伤性脑损伤(traumatic brain injury,TBI)是指机械性外力作用于头部时发生的损伤,导致一个或者多个病变,如颅内损伤、神经病学或者神经心理学改变、意识障碍或者死亡。TBI可因直接打击、缺血缺氧性脑损伤、炎性介质、细胞因子及氧自由基等机制诱发神经元死亡。TBI发生发展过程中产生了大量生物分子标志物,深入研究TBI后生物分子标志物的变化及其规律,对法医学鉴定及临床治疗都有重大意义。本文结合相关文献概述了TBI相关生物分子标志物的研究进展,为寻找更精确的与TBI诊断相关的生物分子标志物提供参考依据。     

Diagnostic significance of myofibrillar degeneration of cardiocytes in forensic pathology

The incidence of myofibrillar degeneration (MFD) was studied in the following different forensic-pathological diagnostic groups of 25 cases each: acute morphine intoxication, acute carbon monoxide intoxication, hanging, strangulation by hand/ligature, drowning, acute hemorrhagic shock, lethal acute brain injury, explainable death of babies or infants and sudden infant death syndrome, together with 18 cases of intoxication with various drugs. The MFD was demonstrated by the Luxol-fast-blue reaction, with two types of phenomena being differentiated, namely cross-band lesions and diffuse staining. All diagnostic groups included cases of MFD of differing degrees. Cross-band lesions were observed in practically all cases of hanging, strangulation and acute hemorrhagic shock. Diffuse stain was noted particularly in cases of drowning and acute brain injury. The diagnostic significance is discussed.     

Can Renal Acute Tubular Necrosis Be Differentiated from Autolysis at Autopsy?*

Abstract: We investigate the morphological characteristics that may differentiate between ischemic acute tubular necrosis (ATN) and autolysis in postmortem samples. Renal tissue from 57 postmortem cases with an antemortem diagnosis of ATN and 57 age-/sex-matched control cases were examined for 10 morphological characteristics: epithelial proliferation (Ki-67 immunoperoxidase positivity), fibrin thrombi, tubular epithelial whorls, mitoses, casts, autolysis, tubulorrhexis, epithelial flattening, interstitial inflammation, and interstitial expansion. Tubular epithelial whorls were found in 16 ATN cases and were absent in controls. These findings suggest that specific morphological criteria may distinguish ischemic ATN from autolysis. Diagnoses of ATN may be confirmed using these combined criteria as contributing to cause of death and/or to ascertain previously undiagnosed cases of ATN postmortem.     

Tissue-specific differences in mRNA quantification of glucose transporter 1 and vascular endothelial growth factor with special regard to death investigations of fatal injuries

Glucose transporter 1 (GLUT1) and vascular endothelial growth factor (VEGF) have been established as being responsible for cellular adaptation to oxygen deficiency in tissue ischemia and hypoxia mediated by hypoxia-inducible factor 1. We hypothesized that mRNA quantification of these factors in autopsy tissue specimens could have diagnostic significance for investigating the pathology of death, especially after injury. Various cases (total, n=119; less than 48h postmortem) were examined, including fatal blunt injury (n=71) and sharp instrument injury (n=18), as well as asphyxia (strangulation/hanging, n=12) and acute myocardial infarction/ischemia (n=18) as controls. Quantification of mRNA by TaqMan real-time RT-PCR and immunostaining were performed for GLUT1 and VEGF in lung, kidney, and skeletal muscle specimens. The postmortem interval showed no significant influence on the relative quantification of mRNA during the early postmortem period. Characteristic results were found in blunt injury cases: both GLUT1 and VEGF mRNAs decreased in the lung but increased in the skeletal muscle depending on survival time. In the kidney, subacute deaths showed higher GLUT1 mRNA levels compared with acute deaths from blunt injury, but no significant change was found for VEGF mRNA. Immunohistochemistry showed visually predominant GLUT1 immunoreactivity in the renal cortex for cases with a longer survival time, coincident with the results at the mRNA level. Tissue-specific differences in mRNA quantification of GLUT1 and VEGF shed light on tissue ischemia/hypoxia and subsequent tissue-dependent pathophysiological changes leading to death after injury.     

心肌缺血猝死心肌中高迁移率族蛋白B-1的表达研究

目的探讨高迁移率族蛋白B-1(High Mobility Group Box protein 1,HMGB1)在心肌缺血猝死后诊断中的法医学价值。方法收集不同案例心肌蜡块分为疑似早期心肌缺血猝死组(早期梗死组)20例、心肌梗死猝死组(心肌梗死组)15例、冠心病非心源性猝死组(对照组1)10例和正常心肌组(对照组2)10例,应用免疫组织化学二步法染色,观察心肌胞核和胞浆中HMGB1表达,用ImagePro Plus 6.0软件计算HMGB1表达的平均光密度,用SPSS 13.0对表达进行数据统计分析。结果 HMGB1在四组心肌细胞胞核中表达均呈阳性;早期梗死组和心肌梗死组胞浆均呈阳性表达,对照组1和对照组2胞浆呈阴性。各组平均光密度分别为0.3031±0.0557、0.3195±0.0523、0.0252±0.0030、0.0207±0.0029,早期梗死组和心肌梗死组的阳性反应与两个对照组相比存在显著差异(P﹤0.01)。结论 HMGB1可作为早期心肌缺血猝死的一个辅助诊断指标。