Why are Wischnewski spots not always present in lethal hypothermia? The results of testing a stress-reduced animal model

Hypothermic sepsis in time since death estimation - a case report

Both hyper- and hypothermia are problematic in temperature based forensic time since death estimation. Hyperthermia may occur in infection, traumatic brain injury, and intoxication. Hypothermia is encountered predominantly in exposure. Sepsis may present itself clinically as hypothermic. Sepsis is not uncommon in the forensic setting and mostly occurs in the context of malpractice accusations. There is usually little overlap between sepsis and typical forensic time since death estimation scenarios of violent or otherwise suspicious deaths. In the presented case, hypothermia and time since death estimations did collide. An inmate was found dead in his jail cell. Wardens claimed they had visually approached him alive relatively shortly prior. Rectal temperature measurements, using two separate crime scene thermometers as well as temperature loggers, revealed low rectal temperature at relatively high ambient temperature. These findings suggested a much longer postmortem interval and consequently raised doubts about the stated timeline. The wardens' claims were however confirmed by camera recordings, which also allowed a reasonable estimate of the true time of death. The cause of death was confirmed as septic organ failure at autopsy, which explained low rectal temperature. The presence of WISCHNEWSKI-spots was noted. When the PRISM-method was applied to the temperature recordings, low rectal temperature at the time of death was detected successfully. However, adaptation of the underlying equation for lower "starting temperature" did not produce satisfactory results. It is concluded that even though hypothermia at the time of death may possibly be detected from temperature data, attempts at time since death estimation for cases of hypothermia by adaptation of the equation should be avoided.

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.

Wischnewski Spots in a Case of Hyperosmolar Hyperglycemic State

ABSTRACT

Wischnewski spots were first described as a common finding in gastric mucosa of decedents exposed to hypothermic environmental conditions. In recent literature, they were also reported in cases of diabetic ketoacidosis, pancreatitis, and fatal burns. Although Wischnewski spots are not specific to cases of hypothermia, we present a case that further supports this contention. We report a case of a middle-aged woman with type 2 diabetes who died of complications of hyperosmolar hyperglycemic state. Although there were no features of hypothermia, she presented with Wischnewski spots in the gastric mucosa. On histology, the gastric mucosa contained brown-black pigmentations with no neutrophilic infiltration. Biochemical analysis from vitreous humor and femoral blood showed marked elevation of glucose levels, low concentration of ketone bodies, pseudohyponatremia, and prerenal azotemia. The autopsy findings in this case discussion shed light to the possible genesis and pathophysiology of Wischnewski spots and highlight an additional differential diagnosis for these lesions.

Biological Mechanisms behind Wischnewsky Spots Finding on Gastric Mucosa: Autopsy Cases and Literature Review

Hypothermia is an emergency caused by the lowering of the central body temperature with a slowdown of basic vital functions. Reduced mobility, old age, psychiatric or metabolic disorders are relevant risk factors. Diagnosis of death from hypothermia is a challenge, as there are no pathognomonic signs, and supportive findings can be inconstant. Wischnewsky Spots (WS) are blackish lesions of gastric mucosa, typically associated with hypothermic death. The pathophysiology of these lesions is still uncertain. The aim of this paper is to investigate the pathological mechanisms determining the appearance of WS by analyzing the current scientific knowledge in this area. We performed a narrative review of the literature published in the last 20 years, comparing the results with three cases of hypothermia reported from our experience. The review proved that WS show a multifactorial etiology, i.e., not only body temperature decrease, but also various extrinsic and intrinsic factors, such as physical and psychological stress, agony, causa mortis and metabolic comorbidities. The review summarizes the current knowledge in the field of incidence, pathology and morphology of WS by proposing some scientific and technical points for clinical and forensic analysis of this phenomenon.

Hypothermia causes platelet activation in the human spleen

BACKGROUND

Accidental hypothermia results in various dysfunctions in the human body. Additionally, coagulation disorder can lead to a life-threatening condition. We previously demonstrated that platelets stored in the spleen were activated and thus triggered coagulation disorder in a mouse model of hypothermia. In the present study, we wanted to investigate if this phenomenon in mice also occurs in humans as a reaction to hypothermia.

METHODS

We analyzed splenic tissue collected from 22 deceased subjects who have died from hypothermia. These samples were compared with 22 control cases not exposed to cold environment. We performed immunohistochemical staining for CD61 (a marker of all platelets) and CD62P (a marker of activated platelets). We also evaluated the morphology of platelets in the spleen with scanning electron microscopy.

RESULTS

Immunohistochemical analysis revealed no significant changes in the amounts of CD61-positive platelets between the hypothermia and control cases. However, the hypothermia cases contained abundant CD62P-positive platelets compared with those of the control cases. Immunohistochemical analysis also revealed that the activated platelets formed aggregates and adhered to splenic sinusoidal endothelial cells in the hypothermia cases. However, we observed no significant fibrin formation around the activated platelets.

CONCLUSIONS

Hypothermia resulted in splenic platelet activation, which may be used as a postmortem marker of hypothermia. The release of activated platelets from the spleen into to circulation upon rewarming may promote coagulation disturbances.

Body temperature-dependent microRNA expression analysis in rats: rno-miR-374-5p regulates apoptosis in skeletal muscle cells via Mex3B under hypothermia

Forensic diagnosis of fatal hypothermia is considered difficult because there are no specific findings. Accordingly, exploration of novel fatal hypothermia-specific findings is important. To elucidate the molecular mechanism of homeostasis in hypothermia and identify novel molecular markers to inform the diagnosis of fatal hypothermia, we focused on microRNA expression in skeletal muscle, which plays a role in cold-induced thermogenesis in mammals. We generated rat models of mild, moderate, and severe hypothermia, and performed body temperature-dependent microRNA expression analysis of the iliopsoas muscle using microarray and quantitative real-time PCR (qRT-PCR). The results show that rno-miR-374-5p expression was significantly induced only by severe hypothermia. Luciferase reporter assay and qRT-PCR results indicated that Mex3B expression was regulated by rno-miR-374-5p and decreased with decreasing body temperature. Gene ontology analysis indicated the involvement of Mex3B in positive regulation of GTPase activity. siRNA analysis showed that Mex3B directly or indirectly regulated Kras expression in vitro, and significantly changed the expression of apoptosis-related genes and proteins. Collectively, these results indicate that rno-miR-374-5p was activated by a decrease in body temperature, whereby it contributed to cell survival by suppressing Mex3B and activating or inactivating Kras. Thus, rno-miR-374-5p is a potential supporting marker for the diagnosis of fatal hypothermia.

Clinicopathological prognostic indicators of survival and pathological findings in cold-stressed Florida manatees Trichechus manatus latirostris

Cold-stress syndrome (CSS) is a leading natural cause of mortality in free-ranging Florida manatees Trichechus manatus latirostris, but comprehensive investigations into blood analyte derangements and prognostic indicators in CSS are lacking. The objectives of this study were to (1) compare admission blood analyte data of manatees pre and post rehabilitation for CSS to identify clinicopathological derangements, (2) identify blood analyte prognostic indicators for survival, and (3) correlate post-mortem anatomic pathological changes with clinicopathological findings to improve the understanding of CS pathophysiology. CSS manatees admitted to a rehabilitation facility between 2007 and 2017 were included: 59 manatees with data for clinicopathological analysis (7 non-survivors and 49 survivors) and 14 manatees with necropsy data (7 with and 7 without blood analyte data). Main interpretive clinicopathological findings indicated systemic inflammation, bone marrow damage, diuresis, malnutrition, tissue necrosis, fat mobilization, hepatic impairment, acid-base imbalances, and gastrointestinal ulceration. The best diagnostically performing prognostic indicators for survival included platelet concentration, aspartate aminotransferase, calcium, and blood urea nitrogen. The main anatomic pathological findings were cutaneous lesions (n = 14), lipid depletion (n = 12), upper gastrointestinal ulceration and/or hemorrhage (n = 9), and pneumonia (n = 5). Based on the identified blood prognostic indicators interpreted in the context of anatomic pathological findings, multi-organ tissue injury, gastrointestinal ulceration and/or hemorrhage, and hemodynamic and platelet derangements are the presumptive major factors of CSS manatee mortality. These results contribute to the understanding of the complex CSS pathophysiology and offer the use of blood analyte prognostic indicators as a clinically applicable tool for the medical care of manatees during rehabilitation, thereby contributing to increased rehabilitation success and conservation of the Florida manatee.

The Veterinary Forensic Necropsy: A Review of Procedures and Protocols

Investigation of animal-related crime, and therefore submission of forensic cases to veterinary pathology facilities, is increasing, yet many veterinary pathologists are unfamiliar and often uncomfortable with involvement in the forensic necropsy. This article discusses various aspects of the forensic necropsy without specific attention to any particular species group or crime. General advice is given on procedures, documentation, and recording of the examination, and the article indicates how these features may differ from those used in investigation of natural disease. It also discusses evidence management, including recordkeeping, identification of evidence, labeling of photographs, and use of standard operating procedures and protocols. Various written and visual methods for documentation of the forensic necropsy are covered, and adjunctive topics such as sample collection, assessment, and description of wounds and taphonomy are included. Cause, mechanism, and manner of death are defined, and guidance to the use of these terms is given. The aim of this article is to offer guidance on procedural aspects of the forensic necropsy that will help those developing their forensic services, contribute to standardization of the provision of forensic veterinary pathology, and build the confidence of the "uncomfortable" forensic veterinary pathologist.

Changes in Surface Charge Density of Blood Cells in Fatal Accidental Hypothermia

The objective of this research was to evaluate postmortem changes concerning electric charge of human erythrocytes and thrombocytes in fatal accidental hypothermia. The surface charge density values were determined on the basis of the electrophoretic mobility measurements of the cells conducted at various pH values of electrolyte solution. The surface charge of erythrocyte membranes after fatal accidental hypothermia increased compared to the control group within whole range of experimental pH values. Moreover, a slight shift of the isoelectric point of erythrocyte membranes towards high pH values was observed. The surface charge of thrombocyte membranes in fatal accidental hypothermia decreased at low pH compared to the control group. However, at pH range 4-9, the values increased compared to the control group. The isoelectric point of thrombocyte membranes after fatal accidental hypothermia was slightly shifted towards low pH values compared to the control group. The observed changes are probably connected with the partial destruction and functional changes of the blood cell structure.

Wischnewski spots in fatal burns

The occurrence of Wischnewski spots in fatal hypothermia has been considered an important indicator of reduced core temperatures, its incidence varying between 40 and 100%. Though many human and animal studies have been conducted to study this phenomenon, the underlying mechanisms contributing to the formation of Wischnewski spots are still not clearly understood. They have been largely reported in human deaths occurring from exposure to freezing temperatures. This is the first reported case of Wischnewski spots observed in a case of fatal burns.

Issues in the diagnosis of hypothermia: a comparison of two geographically separate populations

A review of hypothermic deaths was undertaken using cases from the Charité University, Berlin, Germany and Forensic Science South Australia, Australia. There were 16 cases from Berlin (age range 38-96 years; average 68 years; M:F = 13:3) Wischnewski spots were present in all 16 cases (100%), skin discolouration in nine (56%), and acute pancreatitis and muscle haemorrhage in one case each (6%). There were 62 Australian cases (age range 30-89 years; average 67 years; M:F = 13:18). Wischnewski spots were present in 57 (92%), skin discolouration in seven (11%), vacuolization of renal cells in six (10%), and acute pancreatitis in one (2%). Reporting of the pathological findings in hypothermia may vary among jurisdictions influenced by the location and nature of these deaths and also by reliance on particular features to make the diagnosis. In addition, it is possible that the aetiology of these markers is quite complex and involves not only a significant reduction in core temperature, but the variable and poorly-understood interaction of a number of other factors.