Morphological identification of right ventricular failure in cases of fatal pulmonary thromboembolism

Forensic significance of intracardiac expressions of Nrf2 in acute myocardial ischemia

When exposed to oxidative and electrophilic stress, a protective antioxidant response is initiated by nuclear factor erythroid 2-related factor 2 (Nrf2). However, the extent of its importance in the forensic diagnosis of acute ischemic heart diseases (AIHD), such as myocardial infarction (MI), remains uncertain. On the other hand, immunohistochemical analyses of fibronectin (FN) and the terminal complement complex (C5b-9) prove valuable in identifying myocardial ischemia that precedes necrosis during the postmortem diagnosis of sudden cardiac death (SCD). In this study, we investigated the immunohistochemical levels of Nrf2, FN, and C5b-9 in human cardiac samples to explore their forensic relevance for the identification of acute cardiac ischemia. Heart samples were obtained from 25 AIHD cases and 39 non-AIHD cases as controls. Nrf2 was localized in the nuclei of cardiomyocytes, while FN and C5b-9 were detected in the myocardial cytoplasm. The number of intranuclear Nrf2 positive signals in cardiomyocytes increased in AIHD cases compared to control cases. Additionally, the grading of positive portions of cardiac FN and C5b-9 in the myocardium was also significantly enhanced in AIHD, compared to controls. Collectively, these results indicate that the immunohistochemical investigation of Nrf2 combined with FN, and/or C5b-9 holds the potential for identifying early-stage myocardial ischemic lesions in cases of SCD.

Cardiomyocytes calpain 2 expression: Diagnostic forensic marker for sudden cardiac death caused by early myocardial ischemia and an indicator of the duration of myocardial agonal period?

Sudden cardiac death (SCD) is an unexpected natural death of cardiac etiology and occurs within one hour of the onset of cardiac symptoms in an apparently healthy subject or within 24 h if death is not witnessed. The diagnosis of early myocardial ischemia (EMI) or acute myocardial infarction (AMI) after death is a challenge for forensic pathologists especially when death occurs in a short period of time after the onset of myocardial ischemia. Disorder of cardiomyocytes Ca2+ homeostasis caused by myocardial ischemia during SCD can lead to the activation of calcium-activated non-lysosomal cysteine protease, including calpains. They serve as a proteolytic unit for cell balance and also participate in the processes of apoptosis and necrosis. Agony is a period that precedes somatic death that differs from cellular agony which may evolve for hours after somatic death lasting differently depending on the cell type and mechanism of death. We hypothesize that the expression of calpain 2 in cardiomyocytes could be a specific and sensitive diagnostic forensic marker for SCD caused by EMI and an indicator of the duration of myocardial agonal period. We will conduct a retrospective study that will prove this hypothesis on the respondents who died of SCD by EMI and AMI, instant death by head gunshot and hanging. There is no data on such an analysis in the available literature. The standard hematoxylin-eosin staining will be used to detect cardiac tissue damage. The expression of calpain 2 in cardiomyocytes will be analyzed immunohistochemically. In SCD caused by EMI we expect lower level of calpain 2 expressionin comparison to AMI due to shorter duration of dying. Similar, we predict in the remote region lower calpain 2 expression than in the region of ischemia for both EMI and AMI. In instant death caused by perforating traumatic brain injury we expect mild or no calpain 2 expression throughout the whole myocardium because of very short (immediate) duration of dying. In death caused by hanging calpain 2 expression throughout the whole myocardium should be strong because of longer cellular agonal period. We expect that our results would indicate the immediate activation of calpain 2 in different causes of cardiomyocytes death. From the degree of expression of calpain 2 we could conclude about the duration of cardiomyocytes agony so calpain 2 could be used as a marker for the assessment the duration of somatic and cellular agony.

Forensic significance of intracardiac heme oxygenase-1 expression in acute myocardial ischemia

Heme oxygenase-1 (HO-1), an inducible stress-response protein, exerts anti-oxidant and anti-apoptotic effects. However, its significance in forensic diagnosis of acute ischemic heart diseases (AIHD) such as myocardial infarction (MI) is still unknown. We examined the immunohistochemical expression of HO-1 in the heart samples to discuss their forensic significance to determine acute cardiac ischemia. The heart samples were obtained from 23 AIHD cases and 33 non-AIHD cases as controls. HO-1 positive signals in cardiomyocyte nuclear were detected in 78.2% of AIHD cases, however, that were detected in only 24.2% control cases with statistical difference between AIHD and non-AIHD groups. In contrast to HO-1 protein expression, there was no significant difference in the appearance of myoglobin pallor regions and leukocyte infiltration in the hearts between AIHD and non-AIHD groups. From the viewpoints of forensic pathology, intracardiac HO-1 expression would be considered a valuable marker to diagnose AIHD as the cause of death.

Granulomatosis with polyangiitis (Wegener's granulomatosis): a rare variant of sudden natural death

Granulomatosis with polyangiitis (GPA), formerly known as Wegener's granulomatosis, is the most common form of life-threatening small-vessel vasculitis. Although its exact pathogenesis remains unclear, GPA is believed to belong to the wide complex of autoimmune diseases due to the presence of anti-neutrophil cytoplasmatic antibodies with cytoplasmic staining pattern (c-ANCA) that is expressed in activated neutrophils. GPA predominantly manifests at the upper and lower respiratory tract and the kidneys, but the impairment of multiple organ systems is possible as well. The so-called classical clinical triad of GPA comprises sinusitis, pneumonia, and glomerulonephritis. Despite the fact that there is an elevated risk of mortality for patients suffering from GPA, sudden death due to GPA is a rare and difficult differential diagnosis of sudden natural death in forensic case work. In the present article, the rare case of a 41-year-old male, who died of a sudden death due to previously undiagnosed GPA, is demonstrated. The final diagnosis was feasible by close interdisciplinary collaboration, considering the entire body of findings obtained during autopsy, histopathological investigation, and analysis of the clinical records. Therefore, it remains necessary to point out that especially for rare causes of death, interdisciplinary collaboration is essential in order to concretize the cause of death and exclude rare differential diagnoses of sudden unexpected death of hospitalized patients in forensic case work.

Early markers of myocardial ischemia: from the experimental model to forensic pathology cases of sudden cardiac death

The goal of this study was to assess whether early markers of myocardial ischemia, identified in a previous experimental work, can be applied in forensic pathology cases of sudden, ischemic cardiac death. These markers include desphosphorylated connexin 43 (Cx43), JunB, TUNEL assay, myoglobin, and troponin T. Fourteen cases of sudden cardiac death with gross and/or histological signs of myocardial infarction and 14 cases of sudden cardiac death with signs of early ischemia at histology and positive immunoreactions for fibronectin and C5b-9 were investigated. The control group was represented by 15 hanging (global hypoxia) cases. Immunohistochemical reactions were classified into four degrees and compared among groups. Cx43 and JunB were significantly more expressed in hanging than in ischemia/infarction, but they showed a different distribution in the tissue (sub-endocardial in ischemia/infarction, diffuse in hanging) and a different intensity of the signal. TUNEL assay was significantly more expressed in the group of early ischemia than in myocardial infarction. Myoglobin and troponin T did not show any significantly different expression among the three groups. Depletion markers have a limited application in forensic cases, and this is mostly because positive (depleted) areas are difficult to distinguish from artifactually paler areas. Nuclear markers (JunB and TUNEL), on the other hand, require a well-trained eye and a high magnification in order to be distinguished. Cx43, JunB, and TUNEL assays were confirmed to be early, sensitive markers for myocardial ischemia. Nonetheless, they are not specific, as they are expressed in global hypoxia as well, but with a different tissular distribution.

Early markers for myocardial ischemia and sudden cardiac death

The post-mortem diagnosis of acute myocardial ischemia remains a challenge for both clinical and forensic pathologists. We performed an experimental study (ligation of left anterior descending coronary artery in rats) in order to identify early markers of myocardial ischemia, to further apply to forensic and clinical pathology in cases of sudden cardiac death. Using immunohistochemistry, Western blots, and gene expression analyses, we investigated a number of markers, selected among those which are currently used in emergency departments to diagnose myocardial infarction and those which are under investigation in basic research and autopsy pathology studies on cardiovascular diseases. The study was performed on 44 adult male Lewis rats, assigned to three experimental groups: control, sham-operated, and operated. The durations of ischemia ranged between 5 min and 24 h. The investigated markers were troponins I and T, myoglobin, fibronectin, C5b-9, connexin 43 (dephosphorylated), JunB, cytochrome c, and TUNEL staining. The earliest expressions (≤30 min) were observed for connexin 43, JunB, and cytochrome c, followed by fibronectin (≤1 h), myoglobin (≤1 h), troponins I and T (≤1 h), TUNEL (≤1 h), and C5b-9 (≤2 h). By this investigation, we identified a panel of true early markers of myocardial ischemia and delineated their temporal evolution in expression by employing new technologies for gene expression analysis, in addition to traditional and routine methods (such as histology and immunohistochemistry). Moreover, for the first time in the autopsy pathology field, we identified, by immunohistochemistry, two very early markers of myocardial ischemia: dephosphorylated connexin 43 and JunB.

Different degrees of ischaemic injury in the right and left ventricle in cases of severe, nonfatal, pulmonary embolism

Pulmonary fat embolism (PFE) is a common complication of blunt force traumas with bone fractures. Severe forms cause impedance to right ventricular (RV) ejection, with eventual right heart ischaemia and failure. In a prospective study, we have investigated 220 consecutive autopsy cases (73 females, 147 males, mean age 52.1 years, min 14 years, max 91 years). PFE was detected in 52 cases that were divided into three groups according to the degree of PFE (1-3). A fourth group of cases of violent death without PFE was used for comparison. In each case, histology (H&E, Masson) and immunohistochemistry (fibronectin and C5b-9) were performed on six cardiac samples (anterior, lateral and posterior wall of both ventricles). The degree of cardiac damage was registered in each sample and the mean degree of damage was calculated in each case at the RV and left ventricle (LV). Moreover, a parameter ∆ that is the difference between the mean damage at the RV and the LV was calculated in each case. The results were compared within each group and between the groups. In the present study, we could not detect prevalent RV damage in cases of high degree PFE as we did in our previous investigation. In the group PFE3 the difference of the degree of damage between the RV and LV was higher than the one observed in the groups PFE0-2 with the antibody anti-fibronectin. Prevalent right ventricular stress in cases of severe PFE may explain this observation.

The risk of misinterpreting genital signs of sexual abuse in cadavers: a case report

The significance of genital findings in a case of suspected child sexual abuse has been widely debated in the past decades, as shown by the different classifications available in literature. In the case of postmortem examination, the search for signs of sexual abuse is considerably more difficult because of the superimposition of postmortem modifications, which may determine tissue modifications that can be mistaken for traumatic lesions. This study aims at reporting a case where presumed findings of the first autopsy were denied by histological analysis; in detail, what looked like a possible bruise of the hymen was correctly recognized as hypostasis (livor) of the hymenal tissue by histological analysis. This case report suggests caution in the analysis and discussion of genital lesions found during postmortem examination since the superimposition of cadaveric modifications may radically modify the morphology of soft tissues.

Sensitivity and specificity of NT-proBNP to detect heart failure at post mortem examination

NT-proBNP, a marker of cardiac failure, has been shown to be stable in post mortem samples. The aim of this study was to assess the accuracy of NT-proBNP to detect heart failure in the forensic setting. One hundred sixty-eight consecutive autopsies were included in the study. NT-proBNP blood concentrations were measured using a chemiluminescent immunoassay kit. Cardiac failure was assessed by three independent forensic experts using macro- and microscopic findings complemented by information about the circumstances of body discovery and the known medical story. Area under the receiving operator curve was of 65.4% (CI 95%, from 57.1 to 73.7). Using a standard cut-off value of >220 pg/mL for NT-proBNP blood concentration, heart failure was detected with a sensitivity of 50.7% and a specificity of 72.6%. NT-proBNP vitreous humor values were well correlated to the ones measured in blood (r (2) = 0.658). Our results showed that NT-proBNP can corroborate the pathological findings in cases of natural death related to heart failure, thus, keeping its diagnostic properties passing from the ante mortem to the post mortem setting. Therefore, biologically inactive polypeptides like NT-proBNP seem to be stable enough to be used in forensic medicine as markers of cardiac failure, taking into account the sensitivity and specificity of the test.