The down-regulation of STC2 mRNA may serve as a biomarker for death from mechanical asphyxia

Death from mechanical asphyxia (DMA) is a common cause of death in forensic pathology. However, due to the lack of biomarkers, the authentication of DMA now relies on a series of non-specific signs, which may cause troubles in the judicial trials, especially when the criminal scene is not fully elucidated. To search for the potential biomarkers for DMA, brain samples of DMA and craniocerebral injury groups were screened by microarray. The obtained mRNAs were validated by animal and human samples. Primary cell culture was conducted to explore the biochemical changes under hypoxia. 415 differentially expressed mRNAs between two groups were discovered. Ten mRNAs were examined in both human and animal samples died of different causes of death. Stanniocalcin-2 (STC2) showed significant down-regulation in DMA samples compared to other groups, regardless of PMI, age, or temperature. Cellular experiments indicated that ROS level peaked after 15-min-hypoxic culture, when the expression level of STC2 was significant down-regulated simultaneously. The ER-stress-related proteins also showed potential connection with STC2. In general, it is indicated that the down-regulation of STC2 may serve as a biomarker for DMA.

Identification of differentially expressed proteins in heart of mouse death from smother based on label-free proteomics

Identification of mechanical asphyxia deaths without obvious injuries is a difficult problem for forensic medicine. This study aimed to identify molecular biological markers to predict death from mechanical asphyxia (smother). We established a smother model of mice by over the head with plastic bag tightly until the mice died and applied label-free proteomic technology to identify differentially expressed proteins (DEPs) in heart. A total of 3307 proteins were quantified, and a Fold Change (FC) > 1.2 (or <1/1.2) and Q value < 0.05 were considered as DEPs. Through comparative analysis, we identified 606 DEPs compared to the control group, comprising 219 upregulated and 387 downregulated proteins. Bioinformatics analysis (MCODE analysis) showed that the candidate proteins were mainly involved in regulation of ribosome function, myocardial contraction and calcium regulation, regulation of coagulation and regulation of mitochondrial oxidative respiration. Seven of these proteins were validated using parallel reaction monitoring (PRM), including fibrinogen alpha chain (FIBA), fibrinogen gamma chain (FIBG), Calsequestrin-2 (CASQ2), NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 11 (NDUAB), NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 3 (NDUA3), NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 13 (NDUAD) and Rab7 (RAB7A). CASQ2 and FIBG were further validated by immunohistochemistry. In conclusion, our results may provide some auxiliary indices for identifying the death from mechanical asphyxia.

ER stress-related protein, CHOP, may serve as a biomarker of mechanical asphyxia: a primary study

The precise authentication of death from mechanical asphyxia (DMA) has been a complex problem in forensic medicine. Besides the traditional methods that concern the superficial characterization of the body, researchers are now paying more attention to the biomarkers that may help the identification of DMA. It has been reported that the extremely hypoxic environment created by DMA can cause the specific expression of mitochondria-related protein, which may sever as the biomarkers of DMA authentication. Since endoplasmic reticulum stress (ER stress) has been found to be related to the dysfunction of mitochondria, it is promising to look for the biomarkers of DMA among ER stress-related proteins. In this article, animal and cell experiments were conducted to examine how ER-mitochondria interaction may be influenced in the hypoxic condition caused by DMA primarily. Human samples were then used to verify the possible biomarkers of DMA. We found that ER stress-related protein CHOP was significantly up-regulated within a short-term postmortem interval (PMI) in brain tissue of DMA samples, which may interact with a series of ER stress- and mitochondria-related protein, leading to the apoptosis of the cells. It was also verified in human samples that the expression level of CHOP can sever as a potential biomarker of DMA within a specific PMI.

Entrapment within an ottoman storage bed: an unusual accidental asphyxial death

Herein, we present an uncommon forensic case of death by asphyxia. The victim was a woman whose body at death scene investigation (DSI) was discovered beside an ottoman storage bed. According to the rescue team, who had moved the body before our arrival, the body was originally found in the prone position and stuck with the neck, thorax and arms within the bed. Examination of the body showed hypostasis that was mainly distributed to the face and the lower chest while sparing the neck and the upper chest. The face was markedly swollen, and the eyes were congested with blood. Dissection and histology revealed pulmonary oedema and emphysema of both lungs. Integrating circumstantial, radiology and autopsy data, it was established that the victim, while trapped between the mattress and the edge of the ottoman storage bed, died by mechanical asphyxia due to cervical-thoracic compression and postural asphyxia acting simultaneously.

[Medico-legal aspects of deaths by mechanical asphyxia occurring in Abidjan from 2002 to 2020]

AIM

The aim of this work was to describe the deaths by mechanical as phyxiation that occurred in Abidjan in order to contribute to their prevention.

MATERIAL AND METHODS

This was a retrospective and descriptive study carried out over a period of 19 years (2002-2020) and relating to deaths by mechanical asphyxia treated by Forensic Medicine.

RESULTS

Deaths by mechanical asphyxiation represented 1.23% (756/60,984), concerned men (85%), from the informal sector (39.7%) or pupils/students (34.1%), single people (75%). These deaths occurred on Wednesdays (16.7%), in the afternoon (47.9%), during the month of June (15.2%), by drowning (72.2%), during swimming (56%). The hanging (15.1%) was discovered at the victim's home (95.6%) and the contexts that occurred were financial problems (26%) and depression (25%). Choking (11.4%) followed landslides (79%). Strangulation (1.3%) was criminal (100%) and occurred in the context of settling scores (60%) and crimes of passion (40%). The circumstances of occurrence of drowning and suffocation were accidental respectively in 71.8% and 82.6% of cases while hanging was suicidal (85%).

CONCLUSION

Deaths by mechanical asphyxiation although minimal, constitute a social drama. Their prevention requires the implementation of preventive measures against drowning.

Model for the prediction of mechanical asphyxia as the cause of death based on four biological indexes in human cardiac tissue

Determination of mechanical asphyxia as the cause of death has always been difficult for forensic pathologists, particularly when signs of asphyxia are not obvious on the body. Currently, depending on only physical examination of corpses, pathologists must be cautious when making cause-of-death appraisals. In a previous study, four biomarkers-dual-specificity phosphatase 1 (DUSP1), potassium voltage-gated channel subfamily J member 2 (KCNJ2), miR-122, and miR-3185-were screened in human cardiac tissue from cadavers that died from mechanical asphyxia compared with those that died from craniocerebral injury, hemorrhagic shock, or other causes. Expression of the markers correlated with death from mechanical asphyxia regardless of age, environmental temperature, and postmortem interval. However, a single biological index is not an accurate basis for the identification of the cause of death. In this study, receiver operating characteristic curves of the ΔCq values of the four indexes were generated. The diagnostic accuracy of the indexes was judged according to their area under the curve (DUSP1: 0.773, KCNJ2: 0.775, miR-122: 0.667, and miR-3185: 0.801). Finally, a nomogram was generated, and single blind experiment was conducted to verify the cause of death of mechanical asphyxia.

Identification of the miRNA-3185/CYP4A11 axis in cardiac tissue as a biomarker for mechanical asphyxia

Death by mechanical asphyxia is one of the most difficult conclusions to make in forensic science, especially in corpses displaying slight or no trauma to the surface of the body. Therefore, death by mechanical asphyxia is difficult to prove in medico-legal practice. MicroRNAs (miRNAs) are a class of small, non-coding RNAs involved in the regulation of numerous physiological and pathological cellular processes. In the present study, we demonstrate that significantly increased expression of miR-3185 in cardiac tissues was detected among cases of mechanical asphyxia compared to case of craniocerebral injury, hemorrhagic shock, sudden cardiac death and poisoning. We observed no correlation between the expression of miR-3185 and postmortem interval, age or temperature. Further work indicated that CYP4A11 is a putative target gene of miR-3185 and expressed at a relatively low level in cardiac tissue specimens from cases of mechanical asphyxia compared with specimens from cases of craniocerebral injury, hemorrhagic shock, sudden cardiac death and poisoning. Our results suggest that the miRNA-3185/CYP4A11 axis is associated with mechanical asphyxia-induced death and may provide new insight into asphyxial death investigations.

Value of the serum thyroglobulin level for diagnosing neck compression in postmortem cases

To investigate the relationship between blood thyroglobulin (Tg) levels and neck compression, the Tg levels of right cardiac blood were measured using a chemiluminescence immunoassay in 256 autopsy cases. There were 11 cases in which neck compression was confirmed based on autopsy findings and other information, in which the mean Tg level was 3155 ng/mL (range: 179-16,500 ng/mL). In the remaining cases, the mean Tg level was 4160 ng/mL (range: 0.3-139,000 ng/mL). There was no significant difference between the mean Tg levels of the two groups. In a comparison between the case groups with Tg levels of ≥200 ng/mL and <200 ng/mL, it was found that the frequency of neck compression was significantly higher (P < 0.05) in the ≥200 ng/mL group. The frequency of high Tg levels (≥200 ng/mL) was increased among the cases in which death was caused by neck compression or asphyxia. In a comparison of the median Tg values of right heart blood, left heart blood, whole blood, and femoral venous blood, the median Tg values of whole blood and right heart blood were shown to be about 10 times higher than those of left heart blood and peripheral blood. It is said that high postmortem blood Tg levels are caused by mechanical compression of the thyroid gland. However, high Tg levels were detected in the half of the cases without neck compression. Therefore, neck compression should be diagnosed carefully based on autopsy findings and other information.

Postmortem biochemical investigation results in situations of fatal mechanical compression of the neck region

Biochemical investigations performed in cases of mechanical asphyxia have provided diverging information over time. The purpose of the study presented herein was threefold: to investigate the postmortem stability of a series of molecules (thyroglobulin, iodothyronines, calcitonin, and parathyroid hormone) in blood after death, to determine the same molecules in a series of cases of suicidal hangings for which antemortem serum samples were available, and to measure the same molecules in postmortem serum obtained from different sampling sites thereby evaluating the distribution of these molecules in the specific samples. Preliminary results indicated postmortem stability of thyroglobulin, calcitonin, and parathyroid hormone levels, decreasing total and free T4 levels, and increasing total and free T3 concentrations. Our findings also showed that antemortem mechanical force applied to the neck region (hanging cases) may be accompanied by increased thyroglobulin in peripheral (femoral) blood, though a certain number of cases with nonincreased thyroglobulin levels may be observed. Lastly, our results revealed that hanging, manual, and ligature strangulation cases may be accompanied by increased thyroglobulin, total T3, and free T3 values in postmortem serum specimens obtained from blood sampled at different sampling sites, even in the absence of microscopically identified thyroid gland tissue damage. Such increases are more constant and important in arterial and venous blood samples obtained from sampling sites located in close vicinity of the thyroid gland.

DUSP1 and KCNJ2 mRNA upregulation can serve as a biomarker of mechanical asphyxia-induced death in cardiac tissue

The incidence of death by asphyxia is second to the incidence of death by mechanical injury; however, death by mechanical asphyxia may be difficult to prove in court, particularly in cases in which corpses do not exhibit obvious signs of asphyxia. To identify a credible biomarker of asphyxia, we first examined the expression levels of 47,000 mRNAs in human cardiac tissue specimens from individuals who died of mechanical asphyxia and compared the expression levels with the levels of the corresponding mRNAs in specimens from individuals who died of craniocerebral injury using microarray. We selected 119 differentially expressed mRNAs, examined the expression levels of these mRNAs in 44 human cardiac tissue specimens of individuals who died of mechanical asphyxia, craniocerebral injury, hemorrhagic shock, or other causes. That the expression of dual-specificity phosphatase 1 (DUSP1) and potassium voltage-gated channel subfamily J member 2 (KCNJ2) was upregulated in human cardiac tissues from the mechanical asphyxia group compared with control tissues, regardless of age, environmental temperature, and postmortem interval (PMI), indicating that DUSP1 and KCNJ2 may be associated with mechanical asphyxia-induced death and can thus serve as useful biomarkers of death by mechanical asphyxia.

An Approach to the Classification of Apparent Asphyxial Infant Deaths

Recent evidence indicates that with thorough, high quality death investigations and autopsies, forensic pathologists have recognized that many unexpected infant deaths are, in fact, asphyxial in nature. With this recognition has come a commensurate decrease in, and in some cases, abolition of, the label "sudden infant death syndrome" (SIDS). Current controversies often pertain to how and why some infant deaths are determined to be asphyxial in nature and whether or not apparent asphyxial circumstances are risk factors for SIDS, or rather, harbingers of asphyxial deaths. In an effort to sidestep these controversies, some forensic pathologists elected to instead use the noncommittal label "sudden unexpected infant death" (SUID), leading to the unfortunate consequence of SUID - like SIDS - gaining notoriety as an actual disease that could be diagnosed, studied, and ultimately cured. Although it is not possible to provide death certification guidance for every conceivable type of unexpected infant death, we recognize and propose a simple classification system for overarching themes that cover the vast majority of cases where infants die suddenly and unexpectedly.

Fatal mechanical asphyxia induces changes in energy utilization in the rat brain: An (18)F-FDG-PET study

PURPOSE

This study was designed to evaluate changes in brain glucose metabolism in rats following ligature strangulation.

MATERIALS AND METHODS

Thirteen male Wistar rats were used in the present study, divided into control (n=7) and asphyxia groups (n=6, ligature strangulation). Positron emission tomography (PET) with 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG) was used to evaluate brain glucose metabolism. Rats were scanned for PET-CT, and image data co-registered with a T2WI MRI template using SPM8 software. Image J was employed to draw regions of interest (ROIs) from the MRI template and acquire ROI activity information from the PET images.

RESULTS

In the asphyxia group vs. controls, (18)F-FDG uptake (FU) was decreased in the substantia nigra (25.26%, p<0.001), rhombencephalon (pons/medulla oblongata, 13.92%, p<0.01), hypothalamus (22.06%, p<0.01), ventral tegmentum (10.12%, p<0.05) and amygdala (12.74%, p<0.05); however, FU was increased in motor (18.21%, p<0.05) and visual cortices (19.2%, p<0.05).

CONCLUSIONS

The glucose metabolism distribution map in the asphyxiated rat brains were substantially changed versus controls. PET with (18)F-FDG can demonstrate excitement and inhibition of different brain areas even in cases of ligature strangulation.

Ectopic cervical thymus associated with infant death: 2 case reports and literature review

An ectopic cervical thymus is a rare congenital anomaly that can be located anywhere along the developmental pathway of thymic descent. Most lesions manifest as a cystic mass and have an indolent course. Two fatal cases associated with ectopic cervical thymus in the form of a solid mass are presented in conjunction with a review of the clinicopathological characteristics of the solid form. This report emphasizes the importance of considering a diagnosis of ectopic cervical thymus in infants with neck masses, with or without obstructive symptoms, to prevent possibly fatal outcomes.