Forensic Pathological Analysis of Death Due to Pulmonary Thromboembolism: A Retrospective Study Based on 145 Cases.

ABSTRACT: Pulmonary thromboembolism (PTE) is a common cause of sudden unexpected death in forensic and clinical practice. Although the prevention of thrombosis has been paid more attention in clinical practice in recent years, the number of deaths due to PTE remains extensive. In the present study, 145 cases of fatal PTE were collected and retrospectively analyzed from 2001 to 2020 at the School of Forensic Medicine, China Medical University in Liaoning Province, northeast of China. The demographic characteristics, risk factors of PTE, origins of thrombi, and time interval from the occurrence of main risk factors to PTE were retrospectively analyzed. The 40 to 59 age group accounted for the 51.0% of the total cases. Immobilization, trauma (especially fracture of the pelvis, femur, tibia, or fibula), surgery, cesarean section, and mental disorders were the top 5 high-risk factors. Among the involved cases, 92.9% of the PTE (130/140) occurred within 60 days and peak at 8 to 15 days after the exposure of main risk factors. According to the autopsy findings, 87.6% of the thrombi blocked the bilateral pulmonary arteries at pulmonary hilus, with a maximum diameter of 1.6 cm and a maximum length of 21.9 cm, which were mainly derived from lower limb (65.5%) or pelvic veins (10.3%). Although the embolus limited the pulmonary circulation, there is no difference on the ratio of lung-to-heart weight between PTE and the disease-free accident victims. Overall, our present retrospective study provides important information for the forensic analysis on the cause of death and potential guidance on clinical prevention of PTE.

Candidate biomarkers in brown adipose tissue for post-mortem diagnosis of fatal hypothermia.

Post-mortem diagnosis of fatal hypothermia (FHT) is challenging in forensic practice because traditional morphological and biochemical methods lack specificity. Recent studies have reported that brown adipose tissue (BAT) is activated during cold-induced non-shivering thermogenesis in mammals, but BAT has not been used to diagnose FHT. The aim of this study was to identify novel biomarkers in BAT for FHT based on morphological changes and differential protein expression. Two FHT animal models were created by exposing mice to 4 or -20 °C at 50% humidity. Morphologically, the unilocular lipid droplet content was significantly increased in BAT of FHT model mice compared with that of control mice. Proteomics analysis revealed a total of 283 and 266 differentially expressed proteins (DEPs) between the 4 or -20 °C FHT subgroups and control group, respectively. In addition, 140 proteins were shared between the FHT subgroups. GO and KEGG analyses revealed that the shared DEPs were mainly enriched in pathways associated with metabolism, oxidative phosphorylation, and thermogenesis. Further screening (|log2FC| > 1.6, q-value (FDR) < 0.05) identified GMFB, KDM1A, DDX6, RAB1B, SHMT-1, CLPTM1, and LMF1 as candidate biomarkers of FHT. Subsequent validation experiments were performed in FHT model mice using classic immunohistochemistry and western blotting. RAB1B and GMFB expression was further verified in BAT specimens from human cases of FHT. The results demonstrate that BAT can be used as a target organ for FHT diagnosis employing RAB1B and GMFB as biological markers, thus providing a new strategy for the post-mortem diagnosis of FHT in forensic practice.

Sudden Death Due to Severe Ovarian Hyperstimulation Syndrome: An Autopsy-Centric Case Report.

ABSTRACT: Ovarian hyperstimulation syndrome (OHSS) is a rare iatrogenic disorder associated with controlled ovarian stimulation during assisted reproductive technology. Severe OHSS may impose serious complications, including pleural effusion, acute renal insufficiency, venous thrombosis, and even death, although lethal outcomes are rare in forensic practice. The reported incidence of severe OHSS ranges from 0.008% to 10%. Herein, we present the case of a 29-year-old woman who diagnosed with polycystic ovary syndrome and infertility chose to undergo assisted reproduction. She received leuprorelin acetate and follicle stimulating hormone prior to egg retrieval. Three days after the retrieval procedure, she developed abdominal pain and distension. Later that same day, she died unexpectedly. The subsequent autopsy revealed turbid effusions of pleural and peritoneal cavities, abnormal ovarian enlargement, and duskiness of multiple organ surfaces. Microscopic examination disclosed edema and hemorrhage in follicles of both ovaries, thrombosis within the myocardial matrix, and massive pulmonary edema. Routine toxicology screening was negative. The death was attributed to severe OHSS. This case provides a morphologic reference for clinical and forensic work. Autopsy findings in instances of severe OHSS provide valuable insight into the mechanisms and pathogenesis of this disease.

A novel approach for the forensic diagnosis of drowning by microbiological analysis with next-generation sequencing and unweighted UniFrac-based PCoA.

The diagnosis of drowning is one of the major challenges in forensic practice, especially when the corpse is in a state of decomposition. Novel indicators of drowning are desired in the field of forensic medicine. In the past decade, aquatic bacteria have attracted great attention from forensic experts because they can easily enter the blood circulation with drowning medium, and some of them can proliferate in the corpse. Recently, the advent of next-generation sequencing (NGS) has created new opportunities to efficiently analyze whole microbial communities and has catalyzed the development of forensic microbiology. We presumed that NGS could be a potential method for diagnosing drowning. In the present study, we verified this hypothesis by fundamental experiments in drowned and postmortem-submersed rat models. Our study revealed that detecting the bacterial communities with NGS and processing the data in a transparent way with unweighted UniFrac-based principal coordinates analysis (PCoA) could clearly discriminate the skin, lung, blood, and liver specimens of the drowning group and postmortem submersion group. Furthermore, the acquired information could be used to identify new cases. Taken together, these results suggest that we could build a microbial database of drowned and postmortem-submersed victims by NGS and subsequently use a bioinformatic method to diagnose drowning in future forensic practice.

Nrf2 Ablation Promotes Alzheimer's Disease-Like Pathology in APP/PS1 Transgenic Mice: The Role of Neuroinflammation and Oxidative Stress.

INTRODUCTION: Alzheimer's disease (AD), the most common neurodegenerative disorder, is characterized by the accumulation of amyloid-ß (Aß) peptide and hyperphosphorylated tau protein. Accumulating evidence has revealed that the slow progressive deterioration of AD is associated with oxidative stress and chronic inflammation in the brain. Nuclear factor erythroid 2- (NF-E2-) related factor 2 (Nrf2), which acts through the Nrf2/ARE pathway, is a key regulator of the antioxidant and anti-inflammatory response. Although recent data show a link between Nrf2 and AD-related cognitive decline, the mechanism is still unknown. Thus, we explored how Nrf2 protects brain cells against the oxidative stress and inflammation of AD in a mouse model of AD (APP/PS1 transgenic (AT) mice) with genetic removal of Nrf2. METHODS: The spatial learning and memory abilities of 12-month-old transgenic mice were evaluated using a Morris water maze test. Hippocampal levels of Nrf2, Aß, and p-tauS404 and of astrocytes and microglia were determined by immunostaining. Inflammatory cytokines were determined by ELISA and quantitative real-time polymerase chain reaction (qRT-PCR). Oxidative stress was measured by 8-hydroxydeoxyguanosine immunohistochemistry, and the antioxidant response was determined by qRT-PCR. RESULTS: The spatial learning and memory abilities of AT mice were impaired after Nrf2 deletion. Aß and p-tauS404 accumulation was increased in the hippocampus of AT/Nrf2-KO mice. Astroglial and microglial activation was exacerbated, followed by upregulation of the proinflammatory cytokines IL-1ß, IL-6, and TNF-α. CONCLUSION: Our present results show that Nrf2 deficiency aggravates AD-like pathology in AT mice. This phenotype was associated with increased levels of oxidative and proinflammatory markers, which suggests that the Nrf2 pathway may be a promising therapeutic target for AD.

Postmortem Diagnosis of Fatal Hypothermia by Fourier Transform Infrared Spectroscopic Analysis of Edema Fluid in Formalin-Fixed, Paraffin-Embedded Lung Tissues.

The goal of this study was to investigate whether pulmonary edema could become a specific diagnostic marker for fatal hypothermia using Fourier transform infrared (FTIR) spectroscopy in combination with chemometrics. The spectral profile analysis indicated that hypothermia fatalities associated with pulmonary edema fluid contained more ß-sheet protein conformational structures than the control causes of death, which included sudden cardiac death, brain injury, cerebrovascular disease, mechanical asphyxiation, intoxication, and drowning. Subsequently, the results of principal component analysis (PCA) further revealed that the content of ß-sheet protein conformational structures in the pulmonary edema fluid was the main discriminatory marker between fatal hypothermia and the other causes of death. Ultimately, a robust postmortem diagnostic model for fatal hypothermia using a partial least-squares discriminant analysis (PLS-DA) algorithm was constructed. Pulmonary edema fluid spectra collected from eight new forensic autopsy cases that did not participate in the construction of the diagnostic model were predicted using the model. The results showed the causes of death of all these eight cases were correctly classified. In conclusion, this preliminary study demonstrates that FTIR spectroscopy in combination with chemometrics could be a promising approach for the postmortem diagnosis of fatal hypothermia.

Dynamic cell type-specific expression of Nrf2 after traumatic brain injury in mice.

Nrf2 plays a pivotal role in antioxidant response and anti-inflammation after traumatic brain injury (TBI), and its deletion aggravates TBI-induced brain damage. Previous studies have demonstrated that Nrf2 is activated post TBI, but dynamic changes in expression and cell type-specific characteristics remain unclear. In this study, the Feeney weight-drop contusion model was conducted to mimic TBI, and the ipsilateral cerebral cortex was collected at 1, 3, 7 and 14 days post TBI (dpi). Nrf2 protein levels were observed by western blot. Cell type-specific localization of Nrf2 after TBI was detected at different time intervals by double immunofluorescence staining. NeuN, GFAP, IBA1 and NG2 were used as cell type-specific markers to neurons, astrocytes, microglia and NG2 glia, respectively. After TBI, Nrf2 protein levels peaked at 1 dpi. Robust transient Nrf2 accumulation was co-localized with neurons, which was predominant at 1 dpi. Continuous weak Nrf2 expression was detected in activated astrocytes, and the number of double positive cells peaked at 7 dpi. Inducible widespread immunostaining of Nrf2 was observed in the nucleus of the microglia, and the number of Nrf2+ microglia peaked at 7 dpi. In addition, we also explored colocalization of Nrf2 in NG2 glia, in which the percentage of Nrf2+ in NG2 glia reached a climax at 3 dpi. This study reveals that the accumulation of endogenous Nrf2 might mediate different pathophysical roles in neurons and glias after TBI, the cell-type specific and time-dependent expression provide insights to explain the roles of Nrf2 in different neural cells.

Curcumin plays neuroprotective roles against traumatic brain injury partly via Nrf2 signaling.

Traumatic brain injury (TBI), which leads to high mortality and morbidity, is a prominent public health problem worldwide with no effective treatment. Curcumin has been shown to be beneficial for neuroprotection in vivo and in vitro, but the underlying mechanism remains unclear. This study determined whether the neuroprotective role of curcumin in mouse TBI is dependent on the NF-E2-related factor (Nrf2) pathway. The Feeney weight-drop contusion model was used to mimic TBI. Curcumin was administered intraperitoneally 15 min after TBI induction, and brains were collected at 24 h after TBI. The levels of Nrf2 and its downstream genes (Hmox-1, Nqo1, Gclm, and Gclc) were detected by Western blot and qRT-PCR at 24 h after TBI. In addition, edema, oxidative damage, cell apoptosis and inflammatory reactions were evaluated in wild type (WT) and Nrf2-knockout (Nrf2-KO) mice to explore the role of Nrf2 signaling after curcumin treatment. In wild type mice, curcumin treatment resulted in reduced ipsilateral cortex injury, neutrophil infiltration, and microglia activation, improving neuron survival against TBI-induced apoptosis and degeneration. These effects were accompanied by increased expression and nuclear translocation of Nrf2, and enhanced expression of antioxidant enzymes. However, Nrf2 deletion attenuated the neuroprotective effects of curcumin in Nrf2-KO mice after TBI. These findings demonstrated that curcumin effects on TBI are associated with the activation the Nrf2 pathway, providing novel insights into the neuroprotective role of Nrf2 and the potential therapeutic use of curcumin for TBI.