Biochemical markers of fatal hypothermia

Prominent black esophagus, Wischnewsky spots, and black duodenum in a fatal hypothermia case with an underlying diabetic ketoacidosis

Hypothermia can occur in patients with diabetic ketoacidosis (DKA), and these two conditions can exacerbate each other. Fatal hypothermia and DKA have overlapping features and findings such as Wischnewsky spots (WS), black esophagus, basal subnuclear vacuolization in the renal tubule, dehydration, and increased acetone levels. Therefore, it may be challenging to differentiate or clarify the context of these two conditions. Herein, we report a case of a 49-year-old man with type 1 diabetes who was found lying in his house in mid-winter. He experienced cardiopulmonary arrest 10 h after the initial discovery and died at the hospital. On autopsy, florid left cardiac blood was observed. Black discoloration of the distal part of the esophageal mucosa, widespread WS in the gastric mucosa, and black discoloration of the duodenal mucosa were observed. Histologically, neutrophil infiltration in the esophageal mucosa, neutrophil infiltration and bleeding in the gastric mucosa, basal subnuclear vacuolization and Armanni-Ebstein lesion in the renal tubule epithelium in the kidney, and hyalinization of the islets of Langerhans were observed in the pancreas. Blood acetone and β-hydroxybutyrate levels were 538 µg/mL and 8947 µmol/L, respectively. Glycated hemoglobin A1c and glucose levels were 16.2% and 883 mg/dL, respectively, while C-reactive protein level was 3.64 mg/dL. In conclusion, obnubilation due to DKA was assumed to be the underlying cause of hypothermia, and the combination of these two conditions led to the outcome of death. The concurrent presence of these conditions likely contributed to the conspicuous mucosal findings in the upper gastrointestinal tract.

Establishing vitreous glucose and beta-hydroxybutyrate thresholds to assist in the diagnosis of hypothermia

The post-mortem diagnosis of hypothermia is challenging to establish due to the lack of pathognomonic findings and the confounding problem that any comorbidity may account for death. A 4-year retrospective case-control study was performed to compare the vitreous glucose and beta-hydroxybutyrate (BHB) concentrations between hypothermia deaths and controls. Over the study period 34 cases of hypothermia and 39 controls were analyzed. Hypothermia deaths versus controls had higher mean vitreous glucose (2.93 mmol/L vs. 1.14 mmol/L; p < 0.0001), BHB (1.89 mmol/L vs. 1.35 mmol/L; p = 0.01), and combined glucose+BHB (4.83 mmol/L vs. 2.46 mmol/L; p < 0.0001). Receiver operating characteristic (ROC) curves showed that the best model for predicting hypothermia in all cases was a combined vitreous glucose+BHB threshold of 2.03 mmol/L (sensitivity 88.2 %; specificity 56.4 %). A sub-group analysis broken down by detectable levels of blood ethanol showed that cases of hypothermia with and without ethanol maintained higher median vitreous glucose relative to the controls (2.05 vs. 0.35 mmol/L and 2.70 vs. 0.65 mmol/L; p = 0.02), however median BHB was only significantly elevated when ethanol was absent (1.88 vs. 1.42 mmol/L; p < 0.0001). Subsequent ROC curve analysis demonstrated that a better model for predicting hypothermia was in cases when blood ethanol was absent. In those deaths vitreous BHB alone had the best area under the curve, with an optimum threshold of 1.83 mmol/L (sensitivity 83.3 %; specificity 96.3 %). This study shows that post-mortem vitreous glucose and BHB are useful ancillary studies to assist in the diagnosis of hypothermia. Ethanol however is a confounder and can alter the utility of vitreous BHB when diagnosing hypothermia in those who have consumed alcohol prior to death.

Deaths due to suspected hypothermia in sheep and alpacas on a Manawatū farm in New Zealand in mid-summer

CASE HISTORY

In mid-summer (February), 42 of a flock of 68 ram hoggets (approximately 5 months of age) and two of a group of 14 alpacas on a farm in the Manawatū region of New Zealand were found recumbent or dead following a period of persistent rain, strong winds and relatively low temperatures. The hoggets and alpacas had been shorn 4 and 53 days previously, respectively, and were in adequate to good body condition with access to ad libitum pasture. Post-mortem and histological examinations were undertaken on four hoggets and two alpacas.

CLINICAL FINDINGS

Apart from hypothermic body temperatures from four recumbent hoggets, nothing of significance was identified on clinical or gross pathological examination. Histological changes of vacuolar hepatopathy, renal tubular degeneration and pulmonary congestion were present in all animals examined.

DIAGNOSIS

Based on the history and clinical and pathological findings, hypothermia was highly probable to have been the cause of the deaths.

CLINICAL RELEVANCE

These cases emphasise the importance of shelter for recently shorn sheep and alpacas regardless of the season.

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.

Factors Influencing Postmortem Catecholamine Level and Its Correlations With Agony Time and Cause of Death in Medicolegal Autopsy

BACKGROUND

Catecholamines consisting of epinephrine (EP), norepinephrine (NE), and dopamine (DA) are known as a class of chemical neurotransmitters and hormones essential for regulation of physiological processes including stress responses. Many researchers have tried to establish a relationship between postmortem catecholamine level and agony time or underlying cause of death. However, relevant studies have yielded debatable results. This study was performed to determine characteristics of catecholamine distribution in postmortem specimens with various influencing factors and to assess relationships of postmortem catecholamine levels with agony time and cause of death.

METHODS

A total of 114 autopsy cases were analyzed for catecholamine levels and EP/NE ratios in femoral blood, heart blood, and urine specimens. Postmortem catecholamine levels according to sex, age, medical treatments (cardiopulmonary resuscitation [CPR] and EP injection), postmortem interval (PMI), agonal period, manner of death, and cause of death were evaluated.

RESULTS

Close mutual relationships were noted among femoral and heart blood catecholamine levels. There was no correlation between blood and urine catecholamine levels. Catecholamine levels showed no significant differences according to sex, age, or manner of death. Heart EP and heart EP/NE ratio were significantly higher in the group with CPR. Femoral DA, heart EP, heart NE, heart DA, and urine DA were significantly increased in the group with EP injection. Urine NE and urine DA showed significant differences among PMI groups, with both increased over PMI. In correlation analysis, femoral DA and urine NE displayed weak correlations with PMI. Regarding agony time, femoral and heart DA were significantly increased in long agony group compared to those in the short agony group. With regard to the cause of death, multiple comparison analysis for major categories (natural death, injury, intoxication, asphyxia, drowning, and fire death) revealed a significant increase of femoral NE in asphyxia in comparison with injury. In subgroup analysis for the group without EP injection, femoral NE (P = 0.048), femoral DA (P = 0.039), and heart EP (P = 0.021) showed significant differences between PMI groups.

CONCLUSION

Results of this study have important implications for understanding postmortem catecholamine distribution and their mutual associations, influences of clinical and demographic factors, and relationships with agony time and cause of death in Korean population. Although comprehensive demonstration of catecholamine level as stress index was not possible in the present study, the assessment of postmortem catecholamine levels could be used as a supportive tool in classification of agonal status and differential diagnosis of the cause of death in particular cases. Further investigation is needed on this issue.

Examination of Postmortem β-Hydroxybutyrate Increase in Forensic Autopsy Cases

Ketoacidosis is one of the common diseases that sometimes result in death. In forensic autopsy cases, the measuring of ketone bodies, especially β-hydroxybutyrate (BHB), is useful in diagnosing postmortem ketoacidosis as a cause of death. However, increased BHB values are not always indicative of ketoacidosis. Other causes of death, such as hypothermia, are known to increase BHB values. In addition, sometimes, we experience cases of increased BHB values that are unlikely to be associated with the pathophysiology or the cause of death resulting in an increase in BHB values. In this study, autopsies were performed to determine the relationship between blood BHB values and the postmortem interval (PMI). The patients were divided into four groups: PMI ≤ 24 h, PMI ≤ 48 h, PMI ≤ 72 h, and PMI > 72 h. The BHB values for each group were then compared. Based on the analysis, patients with a PMI ≤ 72 h and those with a PMI > 72 h had significantly higher BHB values than patients with a PMI ≤ 24 h. In conclusion, there remains a possibility that the BHB values increase after death. Forensic pathologists should consider PMI when diagnosing ketoacidosis as the cause of death.

The Importance of BHB Testing on the Post-Mortem Diagnosis of Ketoacidosis

Although beta-hydroxybutyrate (BHB) analysis has proved its importance in forensic pathology, its effects on cause-of-death diagnostics are unaddressed. Therefore, this study aims at evaluating the effects of BHB analysis on the number of deaths by DKA (diabetes ketoacidosis), AKA (alcoholic ketoacidosis), HHS (hyperosmolar hyperglycaemic state), hypothermia, diabetes, alcoholism, and acidosis NOS (not otherwise specified). All 2900 deaths from 2013 through 2019 in which BHB was analysed at the National Board of Forensic Medicine, and 1069 DKA, AKA, HHS, hypothermia, diabetes, alcoholism, and acidosis cases without BHB analysis were included. The prevalence of BHB-positive cases for each cause of death, and trends and proportions of different BHB concentrations, were investigated. The number of BHB analyses/year increased from 13 to 1417. AKA increased from three to 66 and acidosis from one to 20. The deaths from alcoholism, DKA, and hypothermia remained stable. It is unclear why death from alcoholism remained stable while AKA increased. The increase in unspecific acidosis deaths raises the question why a more specific diagnosis had not been used. In conclusion, BHB analysis is instrumental in detecting AKA and acidosis. The scientific basis for the diagnosis of DKA and hypothermia improved, but the number of cases did not change.

Histopathological, histochemical and biochemical postmortem changes in induced fatal hypothermia in rats

Reaching a postmortem diagnosis of hypothermia is challenging in forensic practice. Therefore, this study was conducted to detect the histopathological, histochemical and biochemical changes that occur in adult albino rats following exposure to induced fatal hypothermia. Twenty-four adult albino rats were divided into the negative control, moderate hypothermia, severe hypothermia and hypoxia groups. Rats in the control group were euthanized when those in the moderate hypothermic group died. Blood samples were collected via heart puncture, and the cerebrum, heart, suprarenal gland, kidney, liver and skeletal muscle were removed to investigate the biochemical, histochemical and histopathological changes. Postmortem assessment depicted significant changes in lipid peroxidation, represented by increased malondialdehyde levels in the studied organs of the rats in hypothermic and hypoxia groups. Histopathological examination of the rats’ organs revealed degeneration and necrosis in the hypothermia and hypoxia groups. Sections taken from the severe hypothermic rats revealed a loss of normal cardiac tissue architecture, necrotic changes in the pyramidal cells in the cerebral cortex, and massive necrosis, mainly in the tubules of the renal cortex and medulla. These findings suggest that histological changes might be used as biochemical markers for postmortem diagnosing of fatal hypothermia, particularly in severe hypothermic conditions.

Key points

Death by hypothermia is a serious public health problem worldwide.

Confirming a diagnosis and determining the cause of death in cases of hypothermia are among the most difficult practices in forensic medicine.

Death by hypothermia might be associated with structural abnormalities in various organs.

Studies using different tissue staining techniques will enable an overall illustration of the role of histopathological changes in body organs as indicators of hypothermia.

Characteristics of post-mortem beta-hydroxybutyrate-positivet cases - A retrospective study on age, sex and BMI in 1407 forensic autopsies

BACKGROUND

Post-mortem biochemistry, including the analysis of beta-hydroxybutyrate (BHB), is increasingly employed in forensic medicine, especially in conditions such as diabetes and chronic alcoholism. However, not much is known about the associations between age, body mass index (BMI), and sex and BHB concentrations in ketoacidotic conditions.

AIM

To retrospectively study the association between age, BMI and sex in several conditions, such as diabetic ketoacidosis (DKA), alcoholic ketoacidosis (AKA), and elevated post-mortem BHB concentrations.

METHODS

1407 forensic autopsy cases analysed for BHB were grouped by diagnosis: DKA, AKA, HHS [hyperosmolar hyperglycaemic state], acidosis NOS [not otherwise specified], or hypothermia. Age, sex, BMI and the concentrations of blood alcohol, vitreous glucose and blood BHB were recorded.

RESULTS

Cases of AKA and DKA were most numerous (184 and 156, respectively). In DKA and in its male subgroup, cases with severe ketosis (BHB>1000 µg/g) were younger and had a lower BMI than those with moderate ketosis (BHB 250-1000 µg/g) and controls (P<0.001). In DKA and in its female subgroup, cases with moderate ketosis cases were older (P = 0.0218 and P = 0.0083) than controls. In AKA and in its male subgroup, cases with severe ketosis had a lower BMI than those with moderate ketosis (P = 0.0391 and P = 0.0469) and controls (P<0.001). Cases with moderate ketosis had a lower BMI than controls (P<0.001).

CONCLUSIONS

BHB concentration is associated with BMI in DKA and AKA, and with both BMI and age in DKA. Constitutional factors should, therefore, be considered in potential AKA and DKA cases.

Preliminary Metabolomic Profiling of the Vitreous Humor from Hypothermia Fatalities

The postmortem diagnosis of hypothermia fatalities is often complex due to the absence of pathognomonic lesions and biomarkers. In this study, potential novel biomarkers of hypothermia fatalities were searched in the vitreous humor of known cases of hypothermia fatalities (n = 20) compared to control cases (n = 16), using a targeted metabolomics approach allowing quantitative detection of 188 metabolites. A robust discriminant model with good predictivity was obtained with the supervised OPLS-DA multivariate analysis, showing a distinct separation between the hypothermia and control groups. This signature was characterized by the decreased concentrations of five metabolites (methionine sulfoxide, tryptophan, phenylalanine, alanine, and ornithine) and the increased concentration of 28 metabolites (21 phosphatidylcholines, 3 sphingomyelins, spermine, citrulline, acetylcarnitine, and hydroxybutyrylcarnitine) in hypothermia fatalities compared to controls. The signature shows similarities with already identified features in serum such as the altered concentrations of tryptophan, acylcarnitines, and unsaturated phosphatidylcholines, revealing a highly significant increased activity of methionine sulfoxide reductase, attested by a low methionine sulfoxide-to-methionine ratio. Our results show a preliminary metabolomics signature of hypothermia fatalities in the vitreous humor, highlighting an increased methionine sulfoxide reductase activity.

Relationship between betahydroxybutyrate (BHB) and acetone concentrations in postmortem blood and cause of death

Unexpected death caused by diabetic or alcoholic ketoacidosis is easily overlooked due to the non-specific symptoms. Although the acid betahydroxybutyrate (BHB) is the most abundant ketone body formed in conditions with ketoacidosis, routine analysis in postmortem investigations often only includes the neutral ketone body acetone. This study aims to evaluate the usefulness of implementing routine BHB analysis in postmortem cases, by investigating the relationship between BHB and acetone concentrations in postmortem blood and the main cause of death. From our database of forensic autopsy cases examined from 2012 to 2015, there were 376 cases with BHB and/or acetone detected in postmortem blood that could be paired with data from the Norwegian Cause of Death Registry. Cases were categorized into three groups based on cause of death: "Diabetes-related" (n = 38), "Alcohol-related" (n = 35) and "Other" (n = 303). Analysis of BHB in blood was performed using UHPLC-MS/MS (limit of quantification (LOQ) 52 mg/L) and of acetone using HS-GC-FID (LOQ 87 mg/L). For the purpose of the study, the acetone method was also validated for a LOQ of 23 mg/L. The median BHB concentration was significantly higher in the group of diabetes-related deaths (671 mg/L, range 68-1311 mg/L) compared to the group of alcohol-related (304 mg/L, range 65-1555 mg/L, p <0.001) and other causes of deaths (113 mg/L, range 0-1402 mg/L, p <0.001). In seven deaths (1.9%), the BHB blood concentration was above the suggested pathological threshold of 250 mg/L, without detection of acetone in blood above 23 mg/L. In 15% of deaths by other causes than diabetes or alcohol, a pathologically significant BHB blood concentration was detected. Our results indicate that BHB is a more reliable marker of pathologically significant ketoacidosis than acetone, and we suggest that BHB should be routinely analyzed in postmortem investigations.

Utility of Postmortem Vitreous Beta-Hydroxybutyrate Testing for Distinguishing Sudden from Prolonged Deaths and for Diagnosing Ketoacidosis

A retrospective, cross-sectional analysis of vitreous beta-hydroxybutyrate (BHB) on 967 forensic cases over a two-year period was conducted. Cases were sorted into six categories of death: (i) sudden traumatic/non-natural (ST), (ii) sudden natural (SN), (iii) prolonged traumatic/non-natural (PT), (iv) prolonged natural (PN), (v) diabetic ketoacidosis (DKA), and (vi) alcoholic ketoacidosis (AKA). The mean BHB for all cases was 1.67 mmol/L (17.4 mg/dL; range: 0.11-18.02 mmol/L). The numbers of DKA, AKA, PN, PT, SN, and ST deaths were 21, 5, 155, 258, 275, and 253, respectively. Their mean vitreous BHBs were as follows: 11.04 mmol/L (DKA), 8.88 mmol/L (AKA), 1.56 mmol/L (PN), 1.55 mmol/L (PT), 1.26 mmol/L (SN), and 1.38 mmol/L (ST). There was a statistically significant difference between the mean BHBs of the PN and SN death groups (p < 0.001), as well as between those of the PT and ST death groups (p = 0.004). Given the overlapping ranges seen between the prolonged and sudden death groups, the identified differences did not hold clinical significance. In addition, we sought to determine a threshold value for vitreous BHB to definitely diagnose cases of ketoacidosis. BHB threshold concentrations between 2.5 and 5 mmol/L produced sensitivities >92% and specificities >96%. A receiver operator characteristic curve found 3.43 mmol/L to be the optimal cutoff value, demonstrating a specificity of 98.3% and a sensitivity of 96.2%.

Cortisol levels after cold exposure are independent of adrenocorticotropic hormone stimulation

We previously showed that postmortem serum levels of adrenocorticotropic hormone (ACTH) were significantly higher in cases of hypothermia (cold exposure) than other causes of death. This study examined how the human hypothalamic-pituitary-adrenal axis, and specifically cortisol, responds to hypothermia. Human samples: Autopsies on 205 subjects (147 men and 58 women; age 15-98 years, median 60 years) were performed within 3 days of death. Cause of death was classified as either hypothermia (cold exposure, n = 14) or non-cold exposure (controls; n = 191). Cortisol levels were determined in blood samples obtained from the left and right cardiac chambers and common iliac veins using a chemiluminescent enzyme immunoassay. Adrenal gland tissues samples were stained for cortisol using a rabbit anti-human polyclonal antibody. Cell culture: AtT20, a mouse ACTH secretory cell line, and Y-1, a corticosterone secretory cell line derived from a mouse adrenal tumor, were analyzed in mono-and co-culture, and times courses of ACTH (in AtT20) and corticosterone (in Y-1) secretion were assessed after low temperature exposure mimicking hypothermia and compared with data for samples collected postmortem for other cases of death. However, no correlation between ACTH concentration and cortisol levels was observed in hypothermia cases. Immunohistologic analyses of samples from hypothermia cases showed that cortisol staining was localized primarily to the nucleus rather than the cytoplasm of cells in the zona fasciculata of the adrenal gland. During both mono-culture and co-culture, AtT20 cells secreted high levels of ACTH after 10-15 minutes of cold exposure, whereas corticosterone secretion by Y-1 cells increased slowly during the first 15-20 minutes of cold exposure. Similar to autopsy results, no correlation was detected between ACTH levels and corticosterone secretion, either in mono-culture or co-culture experiments. These results suggested that ACTH-independent cortisol secretion may function as a stress response during cold exposure.

Updated review of postmortem biochemical exploration of hypothermia with a presentation of standard strategy of sampling and analyses

Hypothermia is defined as a core body temperature below 35°C and can be caused by environmental exposure, drug intoxication, metabolic or nervous system dysfunction. This lethal pathology with medico-legal implications is complex to diagnose because macroscopic and microscopic lesions observed at the autopsy and the histological analysis are suggestive but not pathognomonic. Postmortem biochemical explorations have been progressively developed through the study of several biomarkers to improve the diagnosis decision cluster. Here, we present an updated review with novel biomarkers (such as catecholamines O-methylated metabolites, thrombomodulin and the cardiac oxyhemoglobin ratio) as well as some propositional interpretative postmortem thresholds and, to the best of our knowledge, for the first time, we present the most adapted strategy of sampling and analyses to identify biomarkers of hypothermia. For our consideration, the most relevant identified biomarkers are urinary catecholamines and their O-methylated metabolites, urinary free cortisol, blood cortisol, as well as blood, vitreous humor and pericardial fluid for ketone bodies and blood free fatty acids. These biomarkers are increased in response either to cold-mediated stress or to bioenergetics ketogenesis crisis and significantly contribute to the diagnosis by exclusion of death by hypothermia.

Biochemical detection of fatal hypothermia and hyperthermia in affected rat hypothalamus tissues by Fourier transform infrared spectroscopy

It is difficult to determinate the cause of death from exposure to fatal hypothermia and hyperthermia in forensic casework. Here, we present a state-of-the-art study that employs Fourier-transform infrared (FTIR) spectroscopy to investigate the hypothalamus tissues of fatal hypothermic, fatal hyperthermic and normothermic rats to determine forensically significant biomarkers related to fatal hypothermia and hyperthermia. Our results revealed that the spectral variations in the lipid, protein, carbohydrate and nucleic acid components are highly different for hypothalamuses after exposure to fatal hypothermic, fatal hyperthermic and normothermic conditions. In comparison with the normothermia group, the fatal hypothermia and hyperthermia groups contained higher total lipid amounts but were lower in unsaturated lipids. Additionally, their cell membranes were found to have less motional freedom. Among these three groups, the fatal hyperthermia group contained the lowest total proteins and carbohydrates and the highest aggregated and dysfunctional proteins, while the fatal hypothermia group contained the highest level of nucleic acids. In conclusion, this study demonstrates that FTIR spectroscopy has the potential to become a reliable method for the biochemical characterization of fatal hypothermia and hyperthermia hypothalamus tissues, and this could be used as a postmortem diagnostic feature in fatal hypothermia and hyperthermia deaths.

A serum metabolomics signature of hypothermia fatalities involving arginase activity, tryptophan content, and phosphatidylcholine saturation

INTRODUCTION

Hypothermia is a potentially lethal condition whose postmortem diagnosis is often complex to perform due to the absence of pathognomonic lesions and biomarkers. Our first study of human serum and urinary metabolome in hypothermia fatalities sought novel biomarkers with better diagnostic performances than those already existing.

MATERIAL AND METHOD

Thirty-two cases of hypothermia deaths and 16 cases excluding known antemortem exposure to cold or postmortem elements suggesting hypothermia were selected. A targeted metabolomic study allowing the detection and quantitation of 188 metabolites was performed on collected serum and urine using direct flow injection (FIA) and liquid chromatography (LC) separation, both coupled to tandem mass spectrometry (MS/MS). Amino acid quantification was also carried on using an in-house LC-MS/MS method in order to replicate the results obtained with the metabolomic study.

RESULTS

A discriminant metabolic signature allowing a clear separation between hypothermia and control groups was obtained in the serum. This signature was characterized by increased arginase activity and fatty acid unsaturation along with decreased levels of tryptophan in hypothermia fatalities compared to controls. By contrast, no discriminant metabolic signature separating hypothermia from control fatalities was found in urines.

DISCUSSION

The serum metabolic signature of hypothermia fatalities herein observed pointed toward metabolic adaptations that likely aimed at heat production enhancement, endothelial function, and cell membrane fluidity preservation. Novel biomarkers potentially useful in a hypothermia diagnosis were also identified.

Measurement of Cerebral Biomarkers Proving Traumatic Brain Injuries in Post-Mortem Body Fluids

Until now, it is impossible to identify a fatal traumatic brain injury (TBI) before post-mortem radiological investigations or an autopsy take place. It would be preferable to have an additional diagnostic tool such as post-mortem biochemistry to get greater insight into the pathological pathways and survival times after sustaining TBI. Cerebrospinal fluid (CSF) and serum samples of 84 autopsy cases were collected from forensic autopsies with post-mortem intervals (PMI) of up to 148 h. The cases were categorized into a fatal TBI case group (n = 42) and non-TBI controls (n = 42). The values of glial fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF), and neutrophil gelatinase-associated lipocalin (NGAL) were analyzed by means of quantitative chemiluminescent multiplex immunoassays. The main results indicate that the usage of liquid samples with good macroscopic quality is more relevant for meaningful biomarker analyses than the length of the PMI. All three proteins were shown to differentiate TBI fatalities from the controls in CSF. In serum, only GFAP could be shown to be able to identify TBI cases. This study is the first approach to measure the three proteins together in CSF and serum in autopsy cases. Determined threshold values may differentiate between fatal TBI and control cases. The presented results emphasize the possible use of post-mortem biochemistry as a supplemental tool in everyday forensic routine.

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.

Intra-operative predictors of postoperative Takotsubo syndrome in liver transplant recipients-An exploratory case-control study

INTRODUCTION

Takotsubo syndrome (TTS), also known as Takotsubo cardiomyopathy or stress-induced cardiomyopathy, has been described following a variety of surgeries and disease states. The relationship between intra-operative anesthesia management and the development of this syndrome has never been fully elucidated.

OBJECTIVES

The primary objective of this study was to determine the relationship of multiple intra-operative factors on the pathogenesis of TTS.

METHODS

A single-center retrospective review of all liver transplants performed at Mayo Clinic Florida from January 2005 to December 2014. Patients developing left ventricular dilation and a concomitant decrease in ejection fraction, a negative cardiac catheterization, or stress test within 30 days of transplantation were identified. Cases were matched 2:1 to controls with respect to MELD, age, sex, and indication for transplantation. Our evaluation included liver graft characteristics, intra-operative medications, and intra-operative hemodynamic measurements.

RESULTS

We identified 24 cases of TTS from a pool of 1752 transplants, for an incidence of 1.4%. No statistically significant differences in intra-operative measures between the two groups were identified (all P ≥ .08).

CONCLUSION

Our exploratory, single-center retrospective review evaluating 46 intra-operative characteristics found no association with the development of TTS.

A fatal case of hypothermia caused by dog bites

Death from hypothermia usually *We presented a fatal case of hypothermia after being bitten by dog in this article. occurs among people exposed to cold and humid environmental conditions when they are homeless, aged, suffering from natural or psychiatric diseases and drug or alcohol intoxication. A normal healthy person dying from hypothermia due to dog bites is unusual and rare. Here, we present a fatal case of hypothermia following dog bites causing blood loss and multiple wounds on the body. A 56-year-old man was found dead in a remote roadside puddle of a small village, early in the morning. He was naked, and his body trunk and limbs had multiple irregular wounds. Gray animal hairs could be seen in parts of the wound cavities and surrounding areas. In addition, there was a kennel near the scene. Family members argued that the deceased was bitten to death by a dog. However, autopsy revealed several findings which were strongly supportive of fatal hypothermia. Moreover, we saw no obvious changes caused by blood loss, either on the body surface or internal organs. Accordingly, we concluded the true cause of his death was fatal hypothermia; bites from a dog was a necessary causative factor.

Equilibria Between Cell Membranes and Electrolyte Solution: Effect of Fatal Accidental Hypothermia

Equilibria between the membranes of erythrocytes as well as thrombocytes and solution ions in fatal accidental hypothermia were analyzed using a theoretical four-equilibria model. The model was developed to determinate parameters characterizing cell membrane—surrounding ion interactions: the total surface concentrations of both acidic and basic groups C_A, C_B, and association constants K_AH, K_BOH. Knowledge of these parameters was necessary to calculate the theoretical values of surface charge density. The model was validated by curve-fitting the experimental data points to simulated data generated by the model. The experimental and theoretical surface charge density values agree at pH 2–8, at higher pH the deviation was observed.

Death from Hypothermia during a Training Course under "Extreme Conditions": Related to Two Cases

Death from hypothermia following exhaustion or from various complicated pathologies is no longer a frequent cause of death among combat troops. During a training course under "extreme conditions" in the French Alps, two young African officers died. Confronted with these two clinically confirmed cases of hypothermia, the unknown anatomopathological and biological specificities associated with death from hypothermia were highlighted. In these typical and clinically confirmed cases of death from subacute exhaustion hypothermia, none of the signs revealed by the autopsy were specific. Although some recent publications have addressed the utility of postmortem biochemical markers when establishing a diagnosis, with no anamnesis, with no knowledge or analysis of the circumstances of death, and without an in situ examination of the body, it appears difficult, if not impossible, to confirm that death was caused by hypothermia.

Vitreous humor analysis for the detection of xenobiotics in forensic toxicology: a review

Vitreous humor (VH) is a gelatinous substance contained in the posterior chamber of the eye, playing a mechanical role in the eyeball. It has been the subject of numerous studies in various forensic applications, primarily for the assessment of postmortem interval and for postmortem chemical analysis. Since most of the xenobiotics present in the bloodstream are detected in VH after crossing the selective blood-retinal barrier, VH is an alternative matrix useful for forensic toxicology. VH analysis offers particular advantages over other biological matrices: it is less prone to postmortem redistribution, is easy to collect, has relatively few interfering compounds for the analytical process, and shows sample stability over time after death. The present study is an overview of VH physiology, drug transport and elimination. Collection, storage, analytical techniques and interpretation of results from qualitative and quantitative points of view are dealt with. The distribution of xenobiotics in VH samples is thus discussed and illustrated by a table reporting the concentrations of 106 drugs from more than 300 case reports. For this purpose, a survey was conducted of publications found in the MEDLINE database from 1969 through April 30, 2015.

Comprehensive investigation of postmortem glucose levels in blood and body fluids with regard to the cause of death in forensic autopsy cases

The serum glucose level is regulated within a narrow range by multiple factors under physiological conditions, but is greatly modified in the death process and after death. The present study comprehensively investigated glucose levels in blood and body fluids, including pericardial fluid (PCF), cerebrospinal fluid (CSF) and vitreous humor, reviewing forensic autopsy cases (n=672). Right heart blood glucose level was often higher than at other sites, and the CSF glucose level was the lowest, showing greater dissociation in acute/subacute death cases. The glucose level was higher in the diabetic (high HbA1c) than in the non-diabetic (low HbA1c) group at each site (p<0.01-0.0001). Fatal diabetic ketoacidosis cases had evidently high glucose levels at each site; whereas in the non-diabetic group, blood glucose level was higher in fatal alcohol abuse, saltwater drowning, electrocution, cerebrovascular disease and sudden cardiac death due to ischemic heart disease. Fatal methamphetamine (MA) abuse, sepsis, malnutrition (starvation) and hypoglycemia due to antidiabetics showed markedly lower blood glucose levels. Ketones in bilateral cardiac blood and PCF were increased in diabetic ketoacidosis and fatal alcohol abuse as well as in most cases of hyperthermia (heatstroke), hypothermia (cold exposure) and malnutrition. These findings suggest that combined analysis of glucose, HbA1c and ketones in blood and body fluids is useful to investigate not only fatal diabetic metabolic disorders but also death processes due to other causes, including alcohol and MA abuse, as well as thermal disorders, sepsis and malnutrition.

Urinary thrombomodulin and catecholamine levels are interrelated in healthy volunteers immersed in cold and warm water

Severe hypothermia has been shown to influence the levels of catecholamines and thrombomodulin, an endothelial protein essentially involved in the regulation of haemostasis and inflammation. A link between thrombomodulin and catecholamines during cold exposure has also been previously suggested. The aim of this study was to assess the influence of short-term cold exposure without hypothermia on catecholamines and the circulating and urinary thrombomodulin levels. Seven healthy male subjects were immersed in cold water (+10°C) for 10 minutes followed by a 20-minute immersion in +28°C water. Warm water immersion was performed separately for each subject (+30°C for 30 minutes). Thrombomodulin and catecholamine concentrations were measured from pre- and post-immersion (up to 23 hours) samples. In urine, the thrombomodulin level correlated strongly with adrenaline (ρ = 0.806) and noradrenaline (ρ = 0.760) levels. There were no significant differences in thrombomodulin levels between immersion temperatures. Post-immersion urinary thrombomodulin levels were significantly lower than the pre-immersion level at both immersion temperatures. Median concentrations of plasma noradrenaline and urinary adrenaline were higher after exposure to +10°C than to +30°C. Thus, further evidence of the association between thrombomodulin and catecholamines was gained in a physiologically relevant setting in humans. Additionally, it is evident that a short-term cold exposure was not able to elicit changes in the thrombomodulin levels in a follow-up period of up to 23 hours. These findings provide further understanding of the physiological responses to cold during immersion, and of the potential influence of stress on haemostatic and inflammatory responses.

Hypothermia: effects on platelet function and hemostasis

Mild therapeutic hypothermia is considered standard care in the treatment of patients resuscitated from cardiac arrest. With increasingly more frequent concomitant use of platelet-inhibiting drugs, clinicians must be cognizant of the ramifications of hypothermia on platelet function as part of hemostasis. The effects of hypothermia on platelet function have been studied for more than 50 years, but the results are inconsistent and may be related to the circumstances during which hypothermia is achieved. This review summarizes current knowledge of platelet function during hypothermia and the impact on hemostasis.

The postmortem diagnosis of alcoholic ketoacidosis

AIMS

The aim of this article is to review the forensic literature covering the postmortem investigations that are associated with alcoholic ketoacidosis fatalities and report the results of our own analyses.

METHODS

Eight cases of suspected alcoholic ketoacidosis that had undergone medico-legal investigations in our facility from 2011 to 2013 were retrospectively selected. A series of laboratory parameters were measured in whole femoral blood, postmortem serum from femoral blood, urine and vitreous humor in order to obtain a more general overview on the biochemical and metabolic changes that occur during alcoholic ketoacidosis. Most of the tested parameters were chosen among those that had been described in clinical and forensic literature associated with alcoholic ketoacidosis and its complications.

RESULTS

Ketone bodies and carbohydrate-deficient transferrin levels were increased in all cases. Biochemical markers of generalized inflammation, volume depletion and undernourishment showed higher levels. Adaptive endocrine reactions involving insulin, glucagon, cortisol and triiodothyronine were also observed.

CONCLUSIONS

Metabolic and biochemical disturbances characterizing alcoholic ketoacidosis can be reliably identified in the postmortem setting. The correlation of medical history, autopsy findings and biochemical results proves therefore decisive in identifying pre-existing disorders, excluding alternative causes of death and diagnosing alcoholic ketoacidosis as the cause of death.

Cardiac troponin T in forensic autopsy cases

The aim of the present study was to describe the findings of postmortem serum and pericardial fluid (PF) cardiac troponin T (cTnT) in various causes of death with regard to the postmortem interval (PMI) and comorbid cardiovascular disease, using 101 autopsy cases with PMI of 8-141 h divided into 9 groups: cardiovascular disease (CVD), other diseases (OD), poisoning (P), asphyxia (A), drowning (D), hypothermia (H), thoracic trauma (TT), other trauma (OT) and fire fatalities (F). The results suggest that cTnT levels may help to differentiate cardiovascular death from poisoning and non-thoracic trauma, as well as to differentiate cardiovascular and other diseases as cause of death from drowning and hypothermia. However, the effect of PMI, unlike comorbid cardiovascular disease, has to be taken into account.

Glucocorticosteroids as markers of death from hypothermia

In the course of hypothermia, biochemical changes occur that are associated with stimulation of protective thermogenic mechanisms as well as mobilization of internal energy resources mediated by the hormone system. The objective of the investigation was the assessment of validity of determinations of cortisol, cortisone and corticosterone as hypothermia markers in cases of fatal hypothermia combined with concomitant insobriety of the victims. The experimental group consisted of blood samples collected in the course of medico-legal autopsies of 23 hypothermia victims. The controls included blood samples originating from 34 victims of violent sudden deaths (deaths by hanging and traffic road accidents at the scene) and from ten individuals deceased after prolonged agony in consequence of post-traumatic subdural hematomas. In both groups, three subgroups were distinguished that included cases with ethanol levels within the following ranges: 0.0-0.99, 1.0-2.99 and ≥3.0‰. The comparison of determination results showed that irrespectively of blood ethanol concentration, cortisol, cortisone and corticosterone levels seen in hypothermia victims were significantly higher as compared to the controls (P<0.001).