Postmortem serum nitrogen compounds and C-reactive protein levels with special regard to investigation of fatal hyperthermia

Autopsy Findings and Inflammatory Markers in SARS-CoV-2: A Single-Center Experience

Purpose

The systemic inflammatory response related to COVID-19 can be easily investigated in living patients. Unfortunately, not every biomarker is suitable for postmortem analysis since several factors may interfere. The aim of this study was to summarize key histopathological findings within each organ system due to COVID-19 and to assess if serological inexpensive and widely available biomarkers such as CRP, IL-6, fibrinogen and d-Dimers, associated with adverse outcomes in COVID-19, can be implemented in a post-mortem assessment.

Patients and Methods

A total of 60 subjects divided in 2 groups were included. All subjects died outside a hospital setting and therefore did not receive specific or symptomatic therapies that could have modulated the inflammatory response. The first group included 45 subjects in which mandatory autopsy was performed in order to establish the cause of death and macroscopic examination of the lungs was highly suggestive of SARS-CoV-2 infection. As controls (Group 2), 20 subjects who died from polytrauma in high velocity car accidents and suicide were selected. Bronchial fluids collected during the autopsy procedure were used for the RT-PCR diagnosis of SARS-CoV-2 and serum samples were sent for analysis of IL-6, CRP, d-Dimers and fibrinogen.

Results

Compared with the control group, the subjects of the COVID-19 group were older (59±19.5 vs.38±19.15 years, p=0.0002) and had more underlying comorbidities such as hypertension (60% vs 35%, p=0.06) or were overweight (53.3% vs 30%, p=0.08). The levels of CRP, IL-6, fibrinogen and d-Dimers in postmortem plasma samples were significantly higher in COVID-19 subjects than in control group (p< 0.0001). Moreover, the level of IL-6 was significantly higher in overweight patients (r=0.52, P<0.001). In all COVID-19 subjects, the histological examination revealed features corresponding to the exudative and/or proliferative phases of diffuse alveolar damage. Large pulmonary emboli were observed in 7 cases. Gross cardiac enlargement with left ventricular hypertrophy was observed in 19 cases. The most frequent pathological finding of the central nervous system was acute/early-subacute infarction.

Conclusion

Due to the complexity of the inflammatory response, we postulate that a combination of biomarkers, rather than a single laboratory parameter, might be more effective in obtaining a reliable postmortem COVID-19 diagnosis.

Heat-Related Illness in Emergency and Critical Care: Recommendations for Recognition and Management with Medico-Legal Considerations

Hyperthermia is an internal body temperature increase above 40.5 °C; normally internal body temperature is kept constant through natural homeostatic mechanisms. Heat-related illnesses occur due to exposure to high environmental temperatures in conditions in which an organism is unable to maintain adequate homeostasis. This can happen, for example, when the organism is unable to dissipate heat adequately. Heat dissipation occurs through evaporation, conduction, convection, and radiation. Heat disease exhibits a continuum of signs and symptoms ranging from minor to major clinical pictures. Minor clinical pictures include cramps, syncope, edema, tetany, and exhaustion. Major clinical pictures include heatstroke and life-threatening heat stroke and typically are expressed in the presence of an extremely high body temperature. There are also some categories of people at greater risk of developing these diseases, due to exposure in particular geographic areas (e.g., hot humid environments), to unchangeable predisposing conditions (e.g., advanced age, young age (i.e., children), diabetes, skin disease with reduced sweating), to modifiable risk factors (e.g., alcoholism, excessive exercise, infections), to partially modifiable risk factors (obesity), to certain types of professional activity (e.g., athletes, military personnel, and outdoor laborers) or to the effects of drug treatment (e.g., beta-blockers, anticholinergics, diuretics). Heat-related illness is largely preventable.

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.

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.

Post-mortem in situ stability of serum markers of cerebral damage and acute phase response

The aim of the given study was to test the in situ stability of biochemical markers of cerebral damage and acute phase response in the early post-mortem interval to assess their usability for forensic pathology. A monocentric, prospective study investigated post-mortem femoral venous blood samples at four time points obtained within 48 h post-mortem starting at the death of 20 deceased, using commercial immunoassays for the ten parameters: S100 calcium-binding protein B (S100B), glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), brain-derived neurotrophic factor (BDNF), interleukin-6 (IL-6), C-reactive protein (CRP), procalcitonin (PCT), ferritin, soluble tumor necrosis factor receptor type 1 (sTNFR1), and lactate dehydrogenase (LDH). Significant changes in serum levels were observed only later than 2 h after death for all markers. Inter-laboratory comparability was high, and intra-assay precision was sufficient for most markers. Most of the biomarker levels depended on the severity of hemolysis and lipemia but were robust against freeze-thaw cycles. Serum levels increased with longer post-mortem intervals for S100B, NSE, ferritin, sTNFR1, and LDH (for all p < 0.001) but decreased over this period for CRP (p = 0.089) and PCT (p < 0.001). Largely unchanged median values were found for GFAP (p = 0.139), BDNF (p = 0.106), and IL-6 (p = 0.094). Serum levels of CRP (p = 0.059) and LDH (p = 0.109) did not differ significantly between the final ante-mortem (resuscitation) and the first post-mortem sample (moment of death). Collecting the post-mortem blood sample as soon as possible will reduce the influence of post-mortem blood changes. Serum GFAP for detection of cerebral damage as well as serum IL-6 and CRP as proof of acute phase response seemed to be preferable due to their in situ stability in the first 2 days after death.

Intra-individual alterations of serum markers routinely used in forensic pathology depending on increasing post-mortem interval

Post-mortem biochemistry of serum markers has been the subject of numerous studies, but in-situ marker stability after death has not been sufficiently evaluated yet. Such laboratory analyses are especially necessary in the cases of functional deaths without morphological evidence of the death causes and also in cardiac death cases with only very short survival times. The aim of the study was to determine the post-mortem stability of commonly-used serum markers at predefined time points. In 20 cases, peripheral venous samples were taken starting immediately after circulatory arrest and ending 48 hours after death. Serum creatinine, urea, 3-β-hydroxybutyrate, tryptase, myoglobin, troponin T, creatin kinase and creatin kinase-MB have been included. For all markers, we observed increasing marker levels for longer post-mortem intervals. Significant marker level changes began two hours after death. Excessive increases were observed for cardiac and muscle markers. Marker levels showed high intra-assay precision. Furthermore, the markers were robust enough to withstand freeze-thaw cycles. Potential contamination of arteriovenous blood did not influence the post-mortem marker levels. Post-mortem blood should be sampled as soon as possible, as increased post-mortem intervals may heavily change marker levels in-situ in individual cases, whereas the markers are mostly unaffected by laboratory conditions.

Identification of potential markers of fatal hypothermia by a body temperature-dependent gene expression assay

Diagnosis of fatal hypothermia is considered to be difficult in forensic practice and even if findings due to cold exposure are evident, cold exposure is not necessarily a direct cause of death. Identification of useful molecular markers for the diagnosis of fatal hypothermia has not been successful. In this study, to identify novel molecular markers that inform the diagnosis of fatal hypothermia, we focused on skeletal muscle, which plays a role in cold-induced thermogenesis in mammals. We made rat models of mild, moderate, and severe hypothermia and performed body temperature-dependent gene expression analysis in the iliopsoas muscle using next-generation sequencing (NGS). NGS showed that after severe hypothermia, the expression levels of 91 mRNAs were more than double those in mild and moderate hypothermia and control animals. Gene ontology (GO) analysis indicated that these mRNAs are involved in a number of biological processes, including response to stress and lipids, and cellular response to hypoxia. The expression of four genes [connective tissue growth factor (Ctgf), JunB proto-oncogene, AP-1 transcription factor subunit (Junb), nuclear receptor subfamily 4, group A, member 1 (Nr4a1), and Syndecan 4 (Sdc4)] and the level of one protein (CTGF) were induced only by severe hypothermia. These genes and protein are involved in muscle regeneration, tissue repair, and lipid metabolism. These results indicate that heat production to maintain body temperature in a process leading to fatal hypothermia might be performed by the iliopsoas muscle, and that Ctgf, Junb, Nr4a1, and Sdc4 genes are potential diagnostic markers for fatal hypothermia.

Usefulness of postmortem biochemistry in identification of ketosis: Diagnosis of ketoacidosis at the onset of autoimmune type 1 diabetes in an autopsy case with cold exposure and malnutrition

A severely malnourished, Japanese female in her twenties was found dead in her apartment. On autopsy, most of the findings from the internal examination were suggestive of hypothermia. Postmortem biochemistry, however, showed severely increased levels of glycated hemoglobin (HbA1c) and blood and urine glucose levels. Levels of acetone, 3-hydroxybutyric acid, and acetoacetate in various body fluids were also highly increased, indicating ketosis. The serum insulin and c-peptide levels were severely low, and subsequent testing was positive for anti-GAD antibodies. Immunohistochemical examination of the pancreatic islet cells revealed few insulin-positive cells but many glucagon-positive cells on staining. Furthermore, slight invasion of CD8-positive lymphocytes in the pancreatic islets of Langerhans was observed. Results of immunostaining of the pancreatic and bronchial epithelial tissues were partly positive for the Influenza A virus. We concluded that severe ketoacidosis associated with rapid-onset hyperglycemia due to autoimmune type 1 diabetes (AT1D) had occurred shortly before death. However, the ketosis was accompanied by hypothermia and malnutrition as well as diabetic ketoacidosis (DKA). Therefore, we retrospectively collected biochemical data on cases of hypothermia and malnutrition and compared them with the present case. Serum glucose, acetone, 3-hydroxybutyric acid, and acetoacetic acid can be used for screening and diagnosis to distinguish DKA from ketosis due to hypothermia and malnutrition. Therefore, in the present case, we diagnosed that the natural cause of death was due to AT1D. In conclusion, screening investigations for relevant biochemical markers can provide essential information for the diagnosis of metabolic disturbances, which fail to demonstrate characteristic autopsy findings.

Postmortem biochemistry: Current applications

The results of biochemical analyses in specimens obtained postmortem may aid death investigation when diabetic and alcoholic ketoacidosis is suspected, when death may have been the result of drowning, anaphylaxis, or involved a prolonged stress response such as hypothermia, and in the diagnosis of disease processes such as inflammation, early myocardial infarction, or sepsis. There is often cross-over with different disciplines, in particular with clinical and forensic toxicology, since some endogenous substances such as sodium chloride, potassium chloride, and insulin can be used as poisons. The interpretation of results is often complicated because of the likelihood of postmortem change in analyte concentration or activity, and proper interpretation must take into account all the available evidence. The unpredictability of postmortem changes means that use of biochemical measurements in time of death estimation has little value. The use of vitreous humour is beneficial for many analytes as the eye is in a physically protected environment, this medium may be less affected by autolysis or microbial metabolism than blood, and the assays can be performed with due precaution using standard clinical chemistry analysers. However, interpretation of results may not be straightforward because (i) defined reference ranges in life are often lacking, (ii) there is a dearth of knowledge regarding, for example, the speed of equilibration of many analytes between blood, vitreous humour, and other fluids that may be sampled, and (iii) the effects of post-mortem change are difficult to quantify because of the lack of control data. A major limitation is that postmortem vitreous glucose measurements are of no help in diagnosing antemortem hypoglycaemia.

Markers for sepsis diagnosis in the forensic setting: state of the art

Reliable diagnoses of sepsis remain challenging in forensic pathology routine despite improved methods of sample collection and extensive biochemical and immunohistochemical investigations. Macroscopic findings may be elusive and have an infectious or non-infectious origin. Blood culture results can be difficult to interpret due to postmortem contamination or bacterial translocation. Lastly, peripheral and cardiac blood may be unavailable during autopsy. Procalcitonin, C-reactive protein, and interleukin-6 can be measured in biological fluids collected during autopsy and may be used as in clinical practice for diagnostic purposes. However, concentrations of these parameters may be increased due to etiologies other than bacterial infections, indicating that a combination of biomarkers could more effectively discriminate non-infectious from infectious inflammations. In this article, we propose a review of the literature pertaining to the diagnostic performance of classical and novel biomarkers of inflammation and bacterial infection in the forensic setting.

Urea nitrogen, creatinine, and uric acid levels in postmortem serum, vitreous humor, and pericardial fluid

Urea nitrogen, creatinine, and uric acid are relatively stable in postmortem serum and may, therefore, be used for diagnostic purposes when chronic kidney disease and end-stage renal failure are investigated as causes of death. Nevertheless, uncertainties remain in defining the best alternative to postmortem serum for the identification and assessment of significantly decreased kidney function. In this study, we investigated urea nitrogen, creatinine, and uric acid levels in postmortem serum, pericardial fluid, and vitreous humor in a series of medico-legal cases (500 autopsies) with various causes of death. No postmortem interval-related differences were observed in any of the investigated fluids for any analyzed parameter, confirming the biochemical stability of all compounds after death. Data analysis failed to reveal statistically significant differences between postmortem serum and pericardial fluid urea nitrogen, creatinine, and uric acid concentrations. Conversely, statistically significant differences were observed in all analyzed biomarkers between postmortem serum and vitreous humor levels, with lower concentrations of all markers measured in vitreous. The results of this study suggest that, in order to estimate as accurately as possible blood analyte concentrations at the time of death, pericardial fluid should be preferred to vitreous humor.

Forensic molecular pathology: its impacts on routine work, education and training

The major role of forensic pathology is the investigation of human death in relevance to social risk management to determine the cause and process of death, especially in violent and unexpected sudden deaths, which involve social and medicolegal issues of ultimate, personal and public concerns. In addition to the identification of victims and biological materials, forensic molecular pathology contributes to general explanation of the human death process and assessment of individual death on the basis of biological molecular evidence, visualizing dynamic functional changes involved in the dying process that cannot be detected by morphology (pathophysiological or molecular biological vital reactions); the genetic background (genomics), dynamics of gene expression (up-/down-regulation: transcriptomics) and vital phenomena, involving activated biological mediators and degenerative products (proteomics) as well as metabolic deterioration (metabolomics), are detected by DNA analysis, relative quantification of mRNA transcripts using real-time reverse transcription-PCR (RT-PCR), and immunohisto-/immunocytochemistry combined with biochemistry, respectively. Thus, forensic molecular pathology involves the application of omic medical sciences to investigate the genetic basis, and cause and process of death at the biological molecular level in the context of forensic pathology, that is, 'advanced molecular autopsy'. These procedures can be incorporated into routine death investigations as well as guidance, education and training programs in forensic pathology for 'dynamic assessment of the cause and process of death' on the basis of autopsy and laboratory data. Postmortem human data can also contribute to understanding patients' critical conditions in clinical management.

Low plasma C-reactive protein level as an early diagnostic tool for heatstroke vs central nervous system-associated infection in the ED

PURPOSES

Heatstroke (HS) is a life-threatening condition, manifested by systemic inflammation and multiorgan failure. Rapid recognition and treatment are life saving. We report a laboratory-oriented characterization of HS by low plasma C-reactive protein (CRP) level and propose its usefulness in distinguishing this type of hyperpyrexia from central nervous system-associated high core temperature.

METHODS

After institutional review board approval, records of patients admitted to general intensive care unit between August 2008 and September 2011 with core temperature 39.0°C or higher due to HS or meningoencephalitis (ME) were reviewed. Patients' demographics, CRP on admission and 24 to 48 hours later, serum creatinine, creatine phosphokinase, platelets count, international normalized ratio, alanine transaminase, serum pH, and lactate levels were retrieved.

RESULTS

Thirty-six patients were admitted to the intensive care unit with high core temperature: 19 patients, aged 21 to 85 years, had HS; 17 individuals, aged 22 to 81 years, had ME. None of the HS individuals had infection. Twelve HS patients were previously healthy; in 13 patients, the event occurred postexercise. Mean admission CRP levels was 2.1 ± 3.3 mg/L in the HS group compared with 129 ± 84 mg/L in the ME patients (P < .0001); mean 24- to 48-hour CRP levels were 14.6 ± 16.8 vs 139 ± 98 mg/L, respectively (P < .0001). There were no clinically significant differences between the groups regarding laboratory parameters indicative of end-organ damage. Six HS patients underwent computed tomography and/or lumbar puncture before starting intensive cooling, due to misdiagnosis; 5 of them died subsequently.

CONCLUSIONS

Low serum CRP levels characterize non-central nervous system-associated HS. This available laboratory test could identify noninfectious hyperthermic patients upon admission, saving precious time until treatment and avoiding unnecessary diagnostic tests.

Postmortem chemistry update part I

Postmortem chemistry is becoming increasingly essential in the forensic pathology routine and considerable progress has been made over the past years. Biochemical analyses of vitreous humor, cerebrospinal fluid, blood and urine may provide significant information in determining the cause of death or in elucidating forensic cases. Postmortem chemistry may essentially contribute in the determination of the cause of death when the pathophysiological changes involved in the death process cannot be detected by morphological methods (e.g. diabetes mellitus, alcoholic ketoacidosis and electrolytic disorders). It can also provide significant information and useful support in other forensic situations, including anaphylaxis, hypothermia, sepsis and hormonal disturbances. In this article, we present a review of the literature that covers this vast topic and we report the results of our observations. We have focused our attention on glucose metabolism, renal function and electrolytic disorders.