Markers of mechanical asphyxia: immunohistochemical study on autoptic lung tissues

The Role of Protein Degradation in Estimation Postmortem Interval and Confirmation of Cause of Death in Forensic Pathology: A Literature Review

It is well known that proteins are important bio-macromolecules in human organisms, and numerous proteins are widely used in the clinical practice, whereas their application in forensic science is currently limited. This limitation is mainly attributed to the postmortem degradation of targeted proteins, which can significantly impact final conclusions. In the last decade, numerous methods have been established to detect the protein from a forensic perspective, and some of the postmortem proteins have been applied in forensic practice. To better understand the emerging issues and challenges in postmortem proteins, we have reviewed the current application of protein technologies at postmortem in forensic practice. Meanwhile, we discuss the application of proteins in identifying the cause of death, and postmortem interval (PMI). Finally, we highlight the interpretability and limitations of postmortem protein challenges. We believe that utilizing the multi-omics method can enhance the comprehensiveness of applying proteins in forensic practice.

Relationship between intrathrombotic appearance of HSP27 and HSP70 and thrombus ages in a murine model of deep vein thrombosis

Heat shock proteins (HSPs) are molecular chaperones whose primary function is cytoprotection, supporting cell survival under (sub) lethal conditions. They have been implicated in various diseases such as inflammatory diseases and cancer due to their cytoprotective and immunomodulatory effects, and their biological mechanisms have been studied. Central family members include, HSP27, which is induced by various stimuli such as heat shock, hypoxia, hyperoxia, ultraviolet exposure, and nutritional deficiency, and HSP70, which is homeostatically expressed in many organs such as the gastrointestinal tract and has anti-cell death and anti-inflammatory effects. In this study, HSP27 and HSP70 were investigated during thrombus formation and dissolution in a deep vein thrombosis model by immunohistochemistry to determine their involvement in this process and whether their expression could be used as a forensic marker. In the process of thrombus formation and lysis, HSP27 and HSP70 were found to be expressed by immunohistochemical analysis. The role of inhibitors of HSP27 and HSP70 in the pathogenesis of thrombosis in mice was also investigated. When HSP27 or HSP70 inhibitors were administered, thrombi were significantly smaller than in the control group on day 5 after inferior vena cava ligation, indicating pro-thrombotic effects HSP27 and HSP70. If HSP27- or HSP70-positive cells were clearly visible and easily identifiable in the thrombus sections, the thrombus was presumed to be more than 10 days old. Thus, the detection of intrathrombotic HSP27 and HSP70 could forensically provide useful information for the estimation of thrombus ages. Collectively, our study implied that both HSP27 and HSP70 might be molecular targets for thrombus therapy and that the detection of HSP-related molecules such as HSP27 and HSP70 could be useful for the determination of thrombus ages.

Lethal nitrous oxide (N2O) intoxication during surgery: the contribution of immunohistochemistry in identifying the cause of death: a case report

BACKGROUND

Nitrous oxide (N2O) is a gas used in medicine for its analgesic, anxiolytic and amnesic properties. It is a drug considered safe if adequately administered. In the literature, accidental N2O-related deaths are rare. They are mostly related to inhalation of this substance for recreational and autoerotic purposes; rarely are reported deaths due to incorrect administration of medical gas in anesthesia. The diagnosis of death from acute N2O intoxication is complex and is generally an exclusion diagnosis: the macroscopic and microscopic post-mortem signs are entirely nonspecific. Furthermore, the circumstantial data are not always supportive and can even be confusing, mainly if the death occurred inside a hospital.

CASE PRESENTATION

We describe a particular case of death from acute nitrous oxide poisoning in a hospital environment, of a Caucasian male of 72-years-old. The intoxication occurred during a minimally invasive vascular surgery due to an incorrect assembly of the supply lines of medical gases (O2 and N2O). The identification of the cause of death resulted from the analysis of circumstantial data, macroscopic and microscopic autoptic findings, and immunohistochemical investigations based on the search for antibodies anti E-selectin, P-selectin, and HIF 1-α.

CONCLUSION

Although not pathognomonic of asphyxiation by N2O, the latter molecules are a valid and early marker of hypoxic insult. Therefore, in concert with all other findings, it may constitute valid support for the forensic pathologist to ascertain the cause of death in case of suspected intoxication by N2O.

Further explorations into the role of mast cells in deaths associated with fatal asphyxia: an immunohistochemical study utilizing CD 117 marker

Asphyxia-related deaths have always been a challenging task in the speciality of forensic pathology. Apart from helpful macroscopical signs (e.g., strangulation mark, cyanosis, petechial haemorrhage, and lung oedema), recent literature indicates that prolonged asphyxia is sufficient to induce an increase in mast cells (MC). Inflammatory cells migrate from the bone marrow to the lungs, aiding in the diagnosis of fatal asphyxial deaths. HIF1-α, a key regulator protein, is released from lung tissue capillaries during catastrophic hypoxia circumstances, as previously demonstrated in immunohistochemistry (IHC) research. The present study analyzed lung samples from 164 medico-legal autopsy cases, including 57 asphyxia/hypoxia deaths and 107 controls (non-asphyxial deaths). Peribronchial, perivascular and perialveolar MCs were detected using CD117 antibody, and the average of MCs in each of these locations was noted in each case. The results indicated a statistically significant increase in peribronchial and perialveolar mast cells (MC) in fatal asphyxial deaths, including those caused by hanging, drowning, or postural asphyxia. Peri-bronchial MC in lung sections of asphyxial deaths were in the range of 0.2-5.4 and in non-asphyxial samples were in the range of 0.0-2.2. Peri-alveolar MCs in lung sections of asphyxial deaths were in the range of 0.0-0.6 and in non-asphyxial samples were in the range of 0.0-0.2. Our data suggest that mast cells (MC) play an important role in fatal hypoxia-related mortality and CD 117 may be a reliable marker for detection of mast cells in asphyxial deaths. It could be very beneficial to forensic pathologists tasked with differentiating fatal asphyxia fatalities from other causes of death.

Quantitative estimation of TNF-α and IL-3 by using ELISA from human lung tissue in fatal asphyxial deaths

Asphyxia-related deaths have always been a challenging task in the specialty of forensic pathology. Apart from helpful macroscopical signs (e.g., strangulation marks, cyanosis, petechial haemorrhage, and lung edema), recent literature indicates that prolonged asphyxia is sufficient to induce an increase in mast cells (MC). Inflammatory cells migrate from the bone marrow to the lungs, aiding in the diagnosis of fatal asphyxial death. The present study analyzed human lung tissue samples from 90 medico-legal autopsy cases, including 45 asphyxial deaths and 45 controls (non-asphyxial deaths). The cases ranged from 2 to 68 years, with a mean age of 33.23 years. In 90 cases, 74 cases were of males, and 16 were of females. Human lung tissue samples were analyzed by using the sandwich ELISA method. The results indicated a statistically significant increase in TNF-α and IL-3 concentration in fatal asphyxial deaths, including those caused by hanging, drowning, and smothering. Mean ± SD in asphyxial and non-asphyxial cases for the TNF-α and IL-3 concentration statistically analysed. In asphyxial cases, the average IL-3 concentration (Conc.) was 1558.50 ± 350.53 pg/ml, and the average TNF-α concentration (Conc.) was 499.75 ± 479.41 pg/ml. In contrast, in non-asphyxial cases, the average IL-3 concentration (Conc.) was found to be 849.73 ± 484.99 pg/ml, and the average TNF-α concentration (Conc.) was 208.08 ± 81.23 pg/ml. The mean change in IL-3 and TNF-α (Conc.) values are found to significant (<0.01) in asphyxial cases as compared to non-asphyxial cases. The ROC (Receiver operating characteristic curve) analysis revealed that TNF-α (AUC = 0.89) and IL-3 (AUC = 0.87) concentration (conc.) were stronger predictors of asphyxial deaths with an optimal cut-off value of 455.20 pg/ml for TNF-alpha and 1700.62 pg/ml for IL-3 respectively. Our findings imply that mast cells (MC) are critical in fatal hypoxia-related mortality and that TNF-α and IL-3 can be reliable markers for detecting mast cells in asphyxial deaths. It could be very beneficial to forensic pathologists tasked with differentiating fatal asphyxial fatalities from other causes of death.

The potential of using non-coding RNAs in forensic science applications

With the continuous development and integration of molecular biology and forensic science, non-coding RNAs (ncRNAs), especially ncRNAs with regulatory functions such as microRNA, long non-coding RNA, and circular RNA, have recently been actively explored by forensic scholars. In this study, we review the literature on these ncRNAs in various fields of forensic science, including postmortem interval determination, wound age estimation, forensic age assessment, cause of death analysis, and body fluid identification, aiming to evaluate the current research and provide a perspective for future applications.

Useless and limits of Postmortem CT (PMCT) in a complex case of preterm infant murder

The present case-report empathizes the usefulness of post-mortem computed tomography (PMCT) in the detection of live birth signs in a baby found dead, comparing the results with standard autoptic, histologic and immunohistochemical examinations. The report describes the case of a new-born who was thrown out on the footpath from a window of the fifth floor according to the investigative police, whilst the mother has hidden herself immediately after childbirth. PMCT showed diffusely aerated lung parenchyma with signs of severe lung distress, air in the airways with no fluid inside, and air in the upper gastro-intestinal tract, in absence any resuscitation manoeuvres performed on the baby at delivery. PMCT underlined multiple fractures of the skull with degeneration of cerebral parenchyma. All these findings were confirmed by conventional autopsy and histological and immunohistochemical examinations, clinching the usefulness of PMCT in differentiating live births from stillbirths.

Diagnosis of asphyxiation in advanced decomposed corpses by using Oil-Red-O Stain and immunohistochemical technology

BACKGROUND

The unambiguous diagnosis of asphyxiation is still a major challenge for the forensic pathologist, especially in terms of highly advanced decomposed corps.

METHODOLOGY

In order to demonstrate asphyxiation particularly in profoundly putrid bodies we hypothesized that hypoxic stress is basically responsible for generalized fatty degeneration of visceral organs which can be detected by histological examination using a special staining technique referred to as Oil-Red-O Stain (Sudan III-red-B-stain). To test this hypothesis we examined different tissues (myocardium, liver, lung and kidney) of 107 people divided into 5 groups. These are: (i) 71 case-victims who were found in a truck and died most likely due to asphyxiation, whereby any other violent or natural cause of death was ruled out by postmortem examination; (ii) 10 barely decomposed positive-control-victims; (iii) 6 non-decomposed positive-control-victims; iv) 10 drowning non-decomposed positive-control victims, and v) 10 negative-control-victims. Apart from general histological special staining methods, an immunohistochemically approach as a case-control-study on lung tissues of same individuals was carried out by means of using two polyclonal rabbit-antibodies against (i) HIF-1-α (Hypoxia Inducing Factor-1 alpha) and (ii) SP-A (pulmonary surfactant-associated protein A) to detect both the transcription factor and pulmonary surfactants. The positive proof of already either of them gives evidence of death caused by hypoxia.

RESULTS

Histological examination of myocardium, liver and kidney of the 71 case-victims and the 10 positive-control-victims using Oil-Red-O Stain showed a fatty degeneration of small droplet type; there was no evidence for fatty degeneration in tissues of the 10 negative-control-victims. These findings strongly indicate a causal association between oxygen deficiency and generalized fatty degeneration of viscera due to insufficient oxygen supply. In terms of methodology, this special staining technique seems to be very informative, even applicable on decomposed corps. Results of immunohistochemistry indicate that on the one hand the detection of HIF-1α is not possible to perform on (advanced) putrid bodies, whereas the verification of SP-A is still feasible on the other.

CONCLUSION

Positive Oil-Red-O staining and the immunohistochemical detection of SP-A can serve as a serious hint for the diagnosis of asphyxia on putrid corpses, considering other circumstances of death that have been determined.

Combining Oxidative Stress Markers and Expression of Surfactant Protein A in Lungs in the Diagnosis of Seawater Drowning

BACKGROUND AND OBJECTIVES

The diagnosis of seawater drowning (SWD) remains one of the most complex and contentious. It is one of the leading causes of unintentional death around the world. In most cases, the forensic pathologist must reach an accurate diagnosis from the autopsy findings and a series of complementary tests such as histopathological, biological, and chemical studies. Despite the lung being the most affected organ in death by submersion, there are few studies on this type of death's impact on this organ. The aim was to investigate human lung cadavers of forensic cases due to different causes of death, the concentration of the oxidative stress markers malondialdehyde (MDA) and γ-glutamyl-l-cysteinyl glycine (GSH), and the relationship with the expression of surfactant protein A (SP-A) to try to discriminate SWD from other types of causes of death.

MATERIALS AND METHODS

A total of 93 forensic autopsy cases were analyzed. Deaths were classified into three major groups based on the scene, cause of death, and autopsy findings (external foam, frothy fluid in airways, overlapping medial edges of the lungs): (a) drowning in seawater (n = 35), (b) other asphyxia (n = 33), such as hangings (n = 23), suffocations (n = 6), and strangulation (n = 4), and (c) other causes (n = 25), such as multiple suffocations. Oxidative stress markers (MDA and GSH) and the immunohistochemical expression of SP-A were determined in both lungs.

RESULTS

MDA levels were statistically higher in both lungs in cases of SWD than in other causes of death (p = 0.023). Similarly, significantly higher levels of GSH were observed in SWD compared to the rest of the deaths (p = 0.002), which was more significant in the right lung. Higher immunohistochemical expression of SP-A was obtained in the cases of SWD than in the other causes of death, with higher levels in both lungs. The correlation analysis between the levels of oxidative stress (MDA and GSH) in the lung tissue and the expression level of SP-A showed positive and significant results in SWD, both in the alveolar membrane and the alveolar space.

CONCLUSIONS

Determining the levels of MDA and GSH in lung tissue and the expression level of SP-A can be of great importance in diagnosing SWD and the circumstances of death. A better understanding of the physiology of submersion is essential for its possible repercussions in adopting measures in the approach to patients who have survived a submersion process. It is also necessary for forensic pathology to correctly interpret the events that lead to submersion.

Distinguishing Asphyxia from Sudden Cardiac Death as the Cause of Death from the Lung Tissues of Rats and Humans Using Fourier Transform Infrared Spectroscopy

The ability to determine asphyxia as a cause of death is important in forensic practice and helps us to judge whether a case is criminal. However, in some cases where the deceased has underlying heart disease, death by asphyxia cannot be determined by traditional autopsy and morphological observation under a microscope because there are no specific morphological features for either asphyxia or sudden cardiac death (SCD). Here, Fourier transform infrared (FTIR) spectroscopy was employed to distinguish asphyxia from SCD. A total of 40 lung tissues (collected at 0 h and 24 h postmortem) from 20 rats (10 died from asphyxia and 10 died from SCD) and 16 human lung tissues from 16 real cases were used for spectral data acquisition. After data preprocessing, 2675 spectra from rat lung tissues and 1526 spectra from human lung tissues were obtained for subsequent analysis. First, we found that there were biochemical differences in the rat lung tissues between the two causes of death by principal component analysis and partial least-squares discriminant analysis (PLS-DA), which were related to alterations in lipids, proteins, and nucleic acids. In addition, a PLS-DA classification model can be built to distinguish asphyxia from SCD. Second, based on the spectral data obtained from lung tissues allowed to decompose for 24 h, we could still distinguish asphyxia from SCD even when decomposition occurred in animal models. Nine important spectral features that contributed to the discrimination in the animal experiment were selected and further analyzed. Third, 7 of the 9 differential spectral features were also found to be significantly different in human lung tissues from 16 real cases. A support vector machine model was finally built by using the seven variables to distinguish asphyxia from SCD in the human samples. Compared with the linear PLS-DA model, its accuracy was significantly improved to 0.798, and the correct rate of determining the cause of death was 100%. This study shows the application potential of FTIR spectroscopy for exploring the subtle biochemical differences resulting from different death processes and determining the cause of death even after decomposition.

Nitrous oxide intoxication: systematic literature review and proposal of new diagnostic possibilities

Background

Nitrous oxide (N2O), also called “laughing gas,” is the most commonly used inhalation anesthetic in dentistry. The N2O is no longer used, because of the long-term neurologic and cardiovascular sequelae. Due to its sedative and euphoric properties, N2O is often used for recreational use or in some erotic activities. Accidental deaths are mainly associated with the uses of N2O: death can occur from sudden cardiac arrhythmia or, most commonly, acute asphyxiation due to hypoxia. This paper aims to study the literature concerning deaths due to N2O intoxication and highlight pathological findings useful for diagnosis when the crime scene investigation does not reveal any evidence.

Materials and methods

The authors conducted the literature search by PubMed and Scopus databases, searching for articles from 1 January 1970 to 1 March 2020 using the key terms: “Nitrous oxide,” “Laughing gas,” “Hypoxic damage,” “Nitrous oxide anesthesia,” and “Nitrous oxide death.”

Results and discussion

A total of 244 articles were collected. Only 26 articles were included in the systematic review. Most of the deaths from intoxication are due to asphyxiation; the diagnosis is often difficult and immunohistochemistry could be helpful. Nitrous oxide increases the intracellular adhesion molecule expression, E- and P-Selectin (markers of the early inflammatory response), and HIF-1 α (indicative of oxidative stress during ischemia-reperfusion).

Conclusion

The macroscopic and microscopic signs of N2O intoxication are non-specific, but N2O has been proven to cause hypoxic damage to the brain. The suspicion of the presence of the gas in the environment should guide the pathologist. Tissue analyzes provide important information; immunohistochemical stains can confirm hypoxic damage through the use of markers such as HIF-1 α, E-Selectin, and P-Selectin.

Cause of Death in Charred Bodies: Reflections and Operational Insights Based on a Large Cases Study

Our study aims to demonstrate the experience of analyzing fully or partially charred corpses to offer a proper implementation protocol for determining the cause of death. In this study, we present a total of 103 cases obtained from the University of Rome La Sapienza and the University of Pisa archives. All cases were classified based on the extent and severity of burns using a visual method. We divided all cases into two groups. The first group included grade I-II burns (21 cases) without the need for identification. The second group (82 cases) included injuries worse than grade burns II, so all cases were analyzed using an analytical method. For each case, we have documented which of the following analyses have been used and the corresponding findings: inspection, autopsy examination, imaging examination, genetic and toxicological examinations, and histological examination. The results describe the main diagnostic findings and show that only the application of all the above systematic analyses can provide greater accuracy and reliability in describing the causes of death or solving problems, such as identification. In conclusion, we propose an available protocol that defines the main steps of a complete diagnostic pathway that pathologists should follow daily in studying charred bodies.

State-of-the-Art on Wound Vitality Evaluation: A Systematic Review

The vitality demonstration refers to determining if an injury has been caused ante- or post-mortem, while wound age means to evaluate how long a subject has survived after the infliction of an injury. Histology alone is not enough to prove the vitality of a lesion. Recently, immunohistochemistry, biochemistry, and molecular biology have been introduced in the field of lesions vitality and age demonstration. The study was conducted according to the preferred reporting items for systematic review (PRISMA) protocol. The search terms were "wound", "lesion", "vitality", "evaluation", "immunohistochemistry", "proteins", "electrolytes", "mRNAs", and "miRNAs" in the title, abstract, and keywords. This evaluation left 137 scientific papers. This review aimed to collect all the knowledge on vital wound demonstration and provide a temporal distribution of the methods currently available, in order to determine the age of lesions, thus helping forensic pathologists in finding a way through the tangled jungle of wound vitality evaluation.

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.

Immunohistochemistry in the Postmortem Diagnosis of Sepsis: A Systematic Review

It is not uncommon for the forensic pathologist to question whether a deceased person had experienced sepsis that could have either been the cause of or contributed to the person's death. Often, the missing typical pathologic factors or lack of clinical and circumstantial information on the death render the autopsy of a sepsis-related death a difficult task for the forensic pathologist. Several authors emphasize on how an immunohistochemical analysis could help in diagnosing death related to sepsis. The research we carried out analyzes the main scientific studies in the literature, primarily the tracing of 21 immunohistochemical antigens evaluated to help diagnose death related to sepsis. The purpose of this review was to analyze and summarize the markers studied until now and to consider the limitations of immunohistochemistry that currently exist with regard to this particular field of forensic pathology. Immunohistochemistry provided interesting and promising results, but further studies are needed in order for them to be confirmed, so that they may be applied in standard forensic practice.

Acute or chronic pulmonary emphysema? Or both?-A contribution to the diagnosis of death due to violent asphyxiation in cases with pre-existing chronic emphysema

The diagnosis of death due to violent asphyxiation may be challenging if external injuries are missing, and a typical acute emphysema (AE) "disappears" in pre-existing chronic emphysema (CE). Eighty-four autopsy cases were systematically investigated to identify a (histo-) morphological or immunohistochemical marker combination that enables the diagnosis of violent asphyxiation in cases with a pre-existing CE ("AE in CE"). The cases comprised four diagnostic groups, namely "AE", "CE", "acute and chronic emphysema (AE + CE)", and "no emphysema (NE)". Samples from all pulmonary lobes were investigated by conventional histological methods as well as with the immunohistochemical markers Aquaporin 5 (AQP-5) and Surfactant protein A1 (SP-A). Particular attention was paid to alveolar septum ends ("dead-ends") suspected as rupture spots, which were additionally analyzed by transmission electron microscopy. The findings in the four diagnostic groups were compared using multivariate analysis and 1-way ANOVA analysis. All morphological findings were found in all four groups. Based on histological and macroscopic findings, a multivariate analysis was able to predict the correct diagnosis "AE + CE" with a probability of 50%, and the diagnoses "AE" and "CE" with a probability of 86% each. Three types of "dead-ends" could be differentiated. One type ("fringed ends") was observed significantly more frequently in AE. The immunohistochemical markers AQP-5 and SP-A did not show significant differences among the examined groups. Though a reliable identification of AE in CE could not be achieved using the examined parameters, our findings suggest that considering many different findings from the macroscopical, histomorphological, and molecular level by multivariate analysis is an approach that should be followed.

Metabolomics improves the histopathological diagnosis of asphyxial deaths: an animal proof-of-concept model

The diagnosis of mechanical asphyxia remains one of the most difficult issues in forensic pathology. Asphyxia ultimately results in cardiac arrest (CA) and, as there are no specific markers, the differential diagnosis of primitive CA and CA secondary to asphyxiation relies on circumstantial details and on the pathologist experience, lacking objective evidence. Histological examination is currently considered the gold standard for CA post-mortem diagnosis. Here we present the comparative results of histopathology versus those previously obtained by ¹H nuclear magnetic resonance (NMR) metabolomics in a swine model, originally designed for clinical purposes, exposed to two different CA causes, namely ventricular fibrillation and asphyxia. While heart and brain microscopical analysis could identify the damage induced by CA without providing any additional information on the CA cause, metabolomics allowed the identification of clearly different profiles between the two groups and showed major differences between asphyxiated animals with good and poor outcomes. Minute-by-minute plasma sampling allowed to associate these modifications to the pre-arrest asphyxial phase showing a clear correlation to the cellular effect of mechanical asphyxia reproduced in the experiment. The results suggest that metabolomics provides additional evidence beyond that obtained by histology and immunohistochemistry in the differential diagnosis of CA.

Exploring metabolic alterations associated with death from asphyxia and the differentiation of asphyxia from sudden cardiac death by GC-HRMS-based untargeted metabolomics

The determination of cause of death is one of the most important tasks in forensic practice. However, asphyxia is a difficult cause of death to determine, especially when the deceased has an underlying disease that can lead to a sudden unexpected death, such as coronary atherosclerotic heart disease (CAHD, which is the leading cause of sudden cardiac death, SCD), because its determination is currently still based on an exclusion strategy. In this study, gas chromatography coupled with high-resolution mass spectrometry (GC-HRMS)-based untargeted metabolomics was employed to obtain the pulmonary metabolic profiles of rats who died from asphyxia and SCD. First, fourteen metabolites were identified to investigate the mechanism of death from asphyxia, and we proposed some explanations that may account for these metabolic alterations, including the perturbation of amino acid metabolism, lipid metabolism, and energy metabolism (TCA cycle). Second, we discovered eight potential biomarkers to differentiate between asphyxia and SCD as the cause of death. The excellent classification performances of the eight individual biomarkers and their combination in fresh lung tissue were observed. Third, we also explored the relative change in the concentration of the eight metabolites and their classification performance in decomposed tissue (at 24 h postmortem). Lactic acid, pantothenic acid, and the combination of the eight biomarkers can be recognized as perfect classifiers to discriminate asphyxia from SCD even when decomposition has occurred. Our results showed that GC-HRMS-based untargeted metabolomics can be used as a promising tool to explore the metabolic alterations of the death process and to determine the cause of death.

Intrathrombotic appearances of AQP-1 and AQP-3 in relation to thrombus age in murine deep vein thrombosis model

Aquaporins (AQPs) are membrane-bound proteins for water transportation and are useful for diagnosing drowning and wound vitality in forensic pathology. Here, we examined intrathrombotic expression of AQP-1 and AQP-3 using deep vein thrombosis models in mice. To perform immunohistochemical analyses, we used anti-AQP-1 and anti-AQP-3 antibodies. In thrombus samples with the post-ligation intervals of 1 to 5 days, AQP-1⁺ areas were over 70%. At 7 days after the IVC ligation, AQP-1⁺ areas became less than 50%, eventually decreasing to 11% at 21 days. At 3 days after the IVC ligation, AQP-3⁺ cells started to appear from the peripheral area. Thereafter, the positive cell number progressively increased and reached to a peak at 10 days after the IVC ligation. When the intrathrombotic AQP-1⁺ area was as large as the intrathrombotic collagen area or smaller, it would indicate a thrombus age of ≥ 10 days. AQP-3⁺ cell number of > 30 would indicate a thrombus age of 10–14 days. Collectively, our study implied that the detection of AQP-1 and AQP-3 would be useful for the determination of thrombus age.

Immunohistochemistry in the Detection of Early Myocardial Infarction: Systematic Review and Analysis of Limitations Because of Autolysis and Putrefaction

The postmortem diagnosis of acute myocardial infarction is one of the main problems in forensic practice, especially in cases in which death occurs soon after (from minutes to a few hours) the onset of the ischemic damage. Several authors have highlighted the possibility to overcome the limits of conventional histology in this diagnosis by utilizing immunohistochemistry. In the present research, we examined over 30 scientific studies and picked out over 20 main immunohistochemical antigens analyzed with a view to enabling the rapid diagnosis of early myocardial infarction. The aim of our review was to examine and summarize all the principal markers studied to date and also to consider their limitations, including protein alteration because of cadaveric autolysis and putrefaction.

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.

Immunohistochemical expression of P-selectin, SP-A, HSP70, aquaporin 5, and fibronectin in saltwater drowning and freshwater drowning

The diagnosis of drowning is one of the most difficult in forensic medicine. The aim of this study was to analyze pulmonary tissue reactions in death by drowning. In particular, we focused on the immunohistochemical expression of P-selectin, SP-A, HSP70, AQP-5, and fibronectin to investigate our expression in drowning and to understand whether there are differences between saltwater drowning (SWD) and freshwater drowning (FWD), which may indicate a different pathophysiology. We retrospectively investigated 10 cases of SWD (Mediterranean Sea) from the Institute of Legal Medicine of Genoa (Italy), and 10 cases of FWD (Lake of Geneva) from the University Center of Legal Medicine of Geneva (Switzerland). As control group, we examined 10 cases of death by acute external bleeding, characterized by minimal respiratory distress. As compared with controls, in SWD cases, the results showed a decrease of SP-A expression with membrane patterns. Furthermore, we observed a greater SP-A expression with granular pattern in drowning cases without statistically significant difference between SWD and FWD. For the markers AQP-5, HSP70, fibronectin, and P-selectin, no statistically significant differences were found between SWD, FWD, and controls.

Evidence for the Fucoidan/P-Selectin Axis as a Therapeutic Target in Hypoxia-induced Pulmonary Hypertension

Rationale: Pulmonary arterial hypertension (PAH) is characterized by vascular remodeling and excessive proliferation of pulmonary artery smooth muscle cells (PASMCs). Fucoidan, a polysaccharidic ligand of the adhesion molecule P-selectin, exhibits antiproliferative properties. The effects of the fucoidan/P-selectin axis on vascular remodeling and pulmonary hypertension (PH) after hypoxia remain unexplored. Objectives: We aimed to evaluate the therapeutic potential of targeting the fucoidan/P-selectin axis in PH. Methods: Mice with PH induced by chronic hypoxia (35 d) were given either fucoidan (from Fucus vesiculosus) or anti-P-selectin antibody (Rb40.34) during Days 21-35. Right ventricular (RV) function was determined by echocardiography. Vascular morphometry was assessed by immunohistochemistry. Human and experimental PH lungs and PASMCs were used for assessment of P-selectin expression and function. Measurements and Main Results: Fucoidan attenuated chronic hypoxia-induced PH in mice, reducing pulmonary vascular remodeling and restoring RV function. In vitro, fucoidan inhibited hypoxia and growth factor-stimulated PASMC proliferation and migration. Chronic hypoxia caused an upregulation of P-selectin in the medial layer of the small pulmonary arteries. P-selectin was persistently upregulated in PASMCs of human and hypoxia-induced experimental PH. HIF-1α (hypoxia-inducible factor 1α) directly bound to the P-selectin promoter and transcriptionally activated P-selectin in hypoxia. P-selectin blockage resulted in a marked reduction of PASMC proliferation in vitro. Blockage of P-selectin by administration of anti-P-selectin Rb40.34 antibody and P-selectin-deficient mice improved vascular remodeling and restored RV function. Conclusions: Fucoidan is a potent natural adjuvant that represents a promising therapeutic approach for PH. Our data indicate a previously unrecognized role of P-selectin in the proliferative response of PASMCs associated with PH.

Determining the time of death by morphological and immunohistochemical evaluation of collagen fibers in postmortem gingival tissues

The estimation of the post mortem interval (PMI) is still one of the most challenging variables to determine and the different approaches currently used in its estimation generally yield to large post mortem windows. In the present study we combined morphological and immunohistochemical analysis in order to reach a more detailed knowledge on tissue organization and degradation after death. Ultrastructural cellular changes and the extracellular matrix of gingival tissues, collected at different post mortem intervals, were observed by a Transmission Electron Microscopy (TEM), in combination with the immunohistochemical detection of extracellular matrix proteins (i.e. collagen type I and collagen type III) as potential post mortem biochemical markers. The final goal was to find a correlation between morphological modifications, biomarkers expression and the time of death. Samples of gingival tissues obtained from 10 cadavers at different post mortem intervals (short post mortem interval, 1-3 days; mid post mortem interval, 4-6 days; long post mortem interval, 7-9 days) were processed for light microscopy and TEM and they were also immunostained with anti-collagen type I and type III antibodies. Results showed gradual degradation of extracellular matrix in the suboral connective tissue in relation to the different time of death. Moreover PMI was related to an increase of nuclear chromatin condensation and cytoplasmic vacuolization both in epithelial and connective tissues. In conclusion, in addition to traditional forensic approaches to estimate PMI, the combined analyses of cellular morphology, ultrastructure and immunohistochemical expression of collagen proteins allow to better infer the PMI.

Inflammatory reaction patterns of the lung as a response to alveolar hypoxia and their significance for the diagnosis of asphyxiation

Providing evidence of asphyxia death is a challenging issue in forensic pathology. Besides helpful macroscopical signs (e.g. strangulation mark, lung edema), recent data from literature indicate that the time of protracted asphyxia suffices to trigger an increase of giant cells and a migration of inflammatory cells from the bone marrow to the lung, thus offering a help in diagnosis of asphyxia death. In search of new valid asphyxia markers, the present study examined this hypothesis and investigated the leading role of pre-existing lung tissue cells and their functional state in reaction patterns to asphyxia. In specimens of suffocated human lungs following a short (n = 13) and a long asphyxia terminal episode (n = 15), and controls (sudden cardiovascular (n = 11) and traumatic deaths (n = 7)), the count of alveolar phagocytes, megakaryocytes, giant and mast cells, using H&E and toluidine blue staining, was performed. To show macrophage activation, immunohistochemical stainings for CD68, late (25F9) and early (MRP-8/-14) stage inflammatory markers were used. Measuring concentration of tryptase in femoral blood acted as a parameter for mast cell degranulation and consequently their activation. Results showed the lack of specificity of macroscopical parameters despite an association of suffocation with heavy lung edema. No significant differences in the numbers of inflammatory cells in the lungs of different case groups were detected. The doubling of MRP-8- and a five-fold elevation of MRP-14-positive cells compared to cardiovascular controls, proved an early activation state of pre-exiting monocytes in protracted asphyxia. These activated monocytes induced the degranulation of mast cells, resulting in slightly elevated tryptase levels in suffocation compared to cardiovascular controls. In summary, the duration of asphyxia (max. 20 min in cases investigated) only suffices to cause changes on molecular level, being not detectable in any specific macroscopical or histological form in the lung. Despite a potential utility of this molecular insight in individual cases, these results point to the classic doctrine of the evaluation of a rounded overall picture, accentuating on the proof of the ligature tool and the marks of suffocation process.

HIF1α protein and mRNA expression as a new marker for post mortem interval estimation in human gingival tissue

Estimating the post mortem interval (PMI) is still a crucial step in Forensic Pathology. Although several methods are available for assessing the PMI, a precise estimation is still quite unreliable and can be inaccurate. The present study aimed to investigate the immunohistochemical distribution and mRNA expression of hypoxia inducible factor (HIF-1α) in post mortem gingival tissues to establish a correlation between the presence of HIF-1α and the time since death, with the final goal of achieving a more accurate PMI estimation. Samples of gingival tissues were obtained from 10 cadavers at different PMIs (1-3 days, 4-5 days and 8-9 days), and were processed for immunohistochemistry and quantitative reverse transcription-polymerase chain reaction. The results showed a time-dependent correlation of HIF-1α protein and its mRNA with different times since death, which suggests that HIF-1α is a potential marker for PMI estimation. The results showed a high HIF-1α protein signal that was mainly localized in the stratum basale of the oral mucosa in samples collected at a short PMI (1-3 days). It gradually decreased in samples collected at a medium PMI (4-5 days), but it was not detected in samples collected at a long PMI (8-9 days). These results are in agreement with the mRNA data. These data indicate an interesting potential utility of Forensic Anatomy-based techniques, such as immunohistochemistry, as important complementary tools to be used in forensic investigations.

G6PC3, ALDOA and CS induction accompanies mir-122 down-regulation in the mechanical asphyxia and can serve as hypoxia biomarkers

Hypoxia influences different cellular biological processes. To reveal the dynamics of hypoxia's effects on miRNA regulation in vivo, we examined the expression levels of all miRNAs in human brain and heart specimens from cases of mechanical asphyxia compared with those from cases of craniocerebral injury and hemorrhagic shock. We further validated differently expressed miRNAs in another 84 human specimens and rat models. We found that mir-122 was significantly down-regulated and that its putative targets G6PC3, ALDOA and CS were increased in the brain and cardiac tissues in cases of mechanical asphyxia compared with craniocerebral injury and hemorrhagic shock. Our data indicate that mir-122 and its targets G6PC3, ALDOA and CS play roles in the hypoxia responses that regulate glucose and energy metabolism and can serve as hypoxia biomarkers.

Detection of intrathrombotic endothelial progenitor cells and its application to thrombus age estimation in a murine deep vein thrombosis model

Endothelial progenitor cells (EPCs), a newly identified cell type, are bone marrow-derived progenitor cells that co-express stem cell markers and Flk-1 (one of the receptors for vascular endothelial growth factor). In this study, double-color immunofluorescence analysis was performed using anti-CD34 and anti-Flk-1 antibodies in order to examine the time-dependent intrathrombotic appearance of EPCs, using the thrombi of DVT model mice with different thrombus ages (1-21 days). In thrombus cross-section specimens with an age of less than 3 days, CD34+/Flk-1+ EPCs were not detected. EPCs were initially observed in wounds aged 5 days, and their number was increased in thrombi with the advance of thrombus ages. The number of EPCs was the largest in the 10-day thrombus. Moreover, all 15 samples aged 7-14 days had an EPC number of more than 10, and, in 9 of them, the number of intrathrombotic EPCs was over 20. In contrast, in all thrombus samples aged 21 days, the number of intrathrombotic EPCs was less than 20. However, in three of them, the intrathrombotic EPC number was ≥ 10. These observations suggested that an intrathrombotic EPC number exceeding 20 would indicate a thrombus age of approximately 7-14 days.

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.

Back to the Future - Part 1. The medico-legal autopsy from ancient civilization to the post-genomic era

Part 1 of the review "Back to the Future" examines the historical evolution of the medico-legal autopsy and microscopy techniques, from Ancient Civilization to the Post-Genomic Era. In the section focusing on "The Past", the study of historical sources concerning the origins and development of the medico-legal autopsy, from the Bronze Age until the Middle Ages, shows how, as early as 2000 BC, the performance of autopsies for medico-legal purposes was a known and widespread practice in some ancient civilizations in Egypt, the Far East and later in Europe. In the section focusing on "The Present", the improvement of autopsy techniques by Friedrich Albert Zenker and Rudolf Virchow and the contemporary development of optical microscopy techniques for forensic purposes during the 19th and 20th centuries are reported, emphasizing, the regulation of medico-legal autopsies in diverse nations around the world and the publication of international guidelines or best practices elaborated by International Scientific Societies. Finally, in "The Future" section, innovative robotized and advanced microscopy systems and techniques, including their possible use in the bio-medicolegal field, are reported, which should lead to the improvement and standardization of the autopsy methodology, thereby achieving a more precise identification of natural and traumatic pathologies.

Comprehensive Histological and Immunochemical Forensic Studies in Deaths Occurring in Custody

In-custody deaths have several causes, and these include homicide, suicide, natural death from chronic diseases, and unexplained death possibly related to acute stress, asphyxia, excited delirium, and drug intoxication. In some instances, these deaths are attributed to undefined accidents and natural causes even though there is no obvious natural cause apparent after investigation. Understanding these deaths requires a comprehensive investigation, including documentation of circumstances surrounding the death, review of past medical history, drug and toxicology screens, and a forensic autopsy. These autopsies may not always clearly explain the death and reveal only nonspecific terminal events, such as pulmonary edema or cerebral edema. There are useful histologic and biochemical signatures which identify asphyxia, stress cardiomyopathy, and excited delirium. Identifying these causes of death requires semiquantitative morphologic and biochemical studies. We have reviewed recent Bureau of Justice Statistics on in-custody death, case series, and morphological and biochemical studies relevant to asphyxia, stress cardiomyopathy, and excited delirium and have summarized this information. We suggest that regional centers should manage the investigation of these deaths to provide more comprehensive studies and to enhance the expertise of forensic pathologists who would routinely manage potentially complex and difficult cases.

Interaction Between Human Polyomavirus BK and Hypoxia Inducible Factor-1 alpha

BK polyomavirus (BKV) has a worldwide seroprevalence of approximately 90%. After primary infection, BKV establishes a life-long latency within the urogenital tract. The severe immunological impairment occurring in renal transplant recipients leads to BKV reactivation, which may result in polyomavirus associated nephropathy (PVAN). While the transplanted kidney is transiently unperfused, Hypoxia Inducible Factors (HIFs) mediate the cellular response to hypoxia. The α-subunit of HIF isoform 1 (HIF-1α) may interact with several viruses, but until now, there has been no information regarding the interaction between BKV and HIF-1α. The aim of this study is to investigate the possible interaction between HIF-1α and BKV and its potential effect on the pathogenesis of PVAN. Screening of 17 kidney tissue samples revealed that HIF-1α expression was 13.6-fold higher in PVAN tissues compared to control tissues. A luminometric assay in co-transfected African green monkey kidney cells (VERO) demonstrated BKV promoter activation ranging from two to sixfold (P < 0.05) when HIF-1α was over-expressed. A Chromatin ImmunoPrecipitation (ChIP) assay showed structural binding between the BKV promoter and HIF-1α. The amount of BKV DNA increased by threefold in VERO infected cells that were exposed to simulated hypoxia, compared to the cells not subjected to hypoxia. Both ex vivo and in vitro interactions between HIF-1α and BKV were observed, suggesting that HIF-1α, stabilized during transplantation, may be able to bind the BKV promoter and enhance BKV replication. Thus, hypoxia should be considered a risk factor for the development of PVAN in kidney transplant recipients.

Detection of endothelial progenitor cells in human skin wounds and its application for wound age determination

Endothelial progenitor cells (EPCs), a newly identified cell type, are bone marrow-derived progenitor cells that co-express stem cell markers and vascular endothelial growth factor (VEGF) receptor (Flk-1). In this study, a double-color immunofluorescence analysis was carried out using anti-CD34 and anti-Flk-1 antibodies to examine the time-dependent appearance of EPCs, using 52 human skin wounds with different wound ages (Group I, 0-1 days; Group II, 2-6 days; Group III, 7-14 days; and Group IV, 17-21 days). In wound specimens with an age of less than one day, CD34(+)/Flk-1(+) EPCs were not detected. EPCs were initially observed in wounds aged two days, and their number was increased in lesions with advances in wound age. In morphometrical analysis, the average number of EPCs was the highest in the wounds of Group III. Especially, 20 out of 21 wounds aged 7-12 days had >20 EPCs, and all wound samples with postinfliction intervals of 14-21 days had <15 EPCs. These observations at least showed that >20 EPCs would indicate a wound age of 7-12 days. Taken together, our observations indicate the detection of EPCs would be useful for wound age determination.