Navigating cholestasis: identifying inborn errors of bile acid metabolism for precision diagnosis.

Inborn errors of bile acid metabolism (IEBAM) cause cholestasis during the neonatal period, and 8 types of IEBAM have been reported to date. IEBAM accounts for approximately 2% of cases of cholestasis of unknown cause. As only 10 patients have been identified in Japan, IEBAM presents diagnostic challenges due to the similarity of clinical symptoms with biliary atresia, thus necessitating precise differentiation to avoid unnecessary invasive procedures. Laboratory tests in IEBAM are characterized by normal γ-glutamyltransferase (GGT) and serum total bile acid (STBA) levels despite the presence of cholestasis; therefore, measuring STBA and GGT is essential to distinguishing biliary atresia from IEBAM. With suspected IEBAM, liquid chromatography-mass spectrometry (LC/MS) analysis of urinary bile acids is needed to optimize diagnostic and therapeutic efficacy and avoid open cholangiography and initiate treatment for primary bile acids such as cholic acid or chenodeoxycholic acid. This prospective report aims to increase awareness of IEBAM by highlighting the characteristics of general blood test and bile acid profiles from LC/MS analyses of blood, urine, and stool samples.

Forensic significance of intracardiac expressions of Nrf2 in acute myocardial ischemia.

When exposed to oxidative and electrophilic stress, a protective antioxidant response is initiated by nuclear factor erythroid 2-related factor 2 (Nrf2). However, the extent of its importance in the forensic diagnosis of acute ischemic heart diseases (AIHD), such as myocardial infarction (MI), remains uncertain. On the other hand, immunohistochemical analyses of fibronectin (FN) and the terminal complement complex (C5b-9) prove valuable in identifying myocardial ischemia that precedes necrosis during the postmortem diagnosis of sudden cardiac death (SCD). In this study, we investigated the immunohistochemical levels of Nrf2, FN, and C5b-9 in human cardiac samples to explore their forensic relevance for the identification of acute cardiac ischemia. Heart samples were obtained from 25 AIHD cases and 39 non-AIHD cases as controls. Nrf2 was localized in the nuclei of cardiomyocytes, while FN and C5b-9 were detected in the myocardial cytoplasm. The number of intranuclear Nrf2 positive signals in cardiomyocytes increased in AIHD cases compared to control cases. Additionally, the grading of positive portions of cardiac FN and C5b-9 in the myocardium was also significantly enhanced in AIHD, compared to controls. Collectively, these results indicate that the immunohistochemical investigation of Nrf2 combined with FN, and/or C5b-9 holds the potential for identifying early-stage myocardial ischemic lesions in cases of SCD.

A case of hemoperitoneum after percutaneous radiofrequency ablation in a patient with hepatocellular carcinoma.

We report a case of hemoperitoneum after percutaneous radiofrequency ablation in a patient with hepatocellular carcinoma. A 60-year-old female was hospitalized for the treatment of thrombasthenia and cirrhosis caused by chronic Hepatitis C, and computed tomography revealed hepatocellular carcinoma, which was treated by percutaneous radiofrequency ablation. After the ablation, hemoperitoneum was suspected because of the low hemoglobin level with abdominal pain. Approximately 6 h after the ablation treatment, the patient suddenly fell into a shock state and died. In this case, medical treatment-related death including malpractice was suspected, and forensic autopsy was performed. The abdominal cavity contained 910 mL of dark red fluid blood and 210 g of soft hemocoagula. Moreover, several puncture marks were observed on the liver surface and diaphragm, and there was no clear damage to the main arteries and veins. Considering the macroscopic and microscopic findings, the cause of death was assumed as hemorrhagic shock due to the hemoperitoneum caused by the damage to the liver by radiofrequency ablation. It is important to consider all the indications and adverse effects of radiofrequency ablation.

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.

Healthy Patients With AKR1D1 Mutation Not Requiring Primary Bile Acid Therapy: A Case Series.

Δ4-3-Oxosteroid 5ß-reductase (AKR1D1) deficiency typically causes severe cholestasis occurs in newborns, leading to death unless patients are treated with primary bile acids. However, we encountered an AKR1D1 deficiency patient treated with only ursodeoxycholic acid who had cholestasis until about 1 year of age but then grew up healthy without further treatment. We also have been following other healthy patients with AKR1D1 mutation who have never developed cholestasis and have not been treated. However, reports are few, involving 3 patients. To better understand and clinically manage a diverse group of patients with AKR1D1 mutation who do not develop potentially fatal cholestasis in the neonatal period, ongoing accumulation and study of informative cases is needed.

Essential Involvement of Neutrophil Elastase in Acute Acetaminophen Hepatotoxicity Using BALB/c Mice.

Intense neutrophil infiltration into the liver is a characteristic of acetaminophen-induced acute liver injury. Neutrophil elastase is released by neutrophils during inflammation. To elucidate the involvement of neutrophil elastase in acetaminophen-induced liver injury, we investigated the efficacy of a potent and specific neutrophil elastase inhibitor, sivelestat, in mice with acetaminophen-induced acute liver injury. Intraperitoneal administration of 750 mg/kg of acetaminophen caused severe liver damage, such as elevated serum transaminase levels, centrilobular hepatic necrosis, and neutrophil infiltration, with approximately 50% mortality in BALB/c mice within 48 h of administration. However, in mice treated with sivelestat 30 min after the acetaminophen challenge, all mice survived, with reduced serum transaminase elevation and diminished hepatic necrosis. In addition, mice treated with sivelestat had reduced NOS-II expression and hepatic neutrophil infiltration after the acetaminophen challenge. Furthermore, treatment with sivelestat at 3 h after the acetaminophen challenge significantly improved survival. These findings indicate a new clinical application for sivelestat in the treatment of acetaminophen-induced liver failure through mechanisms involving the regulation of neutrophil migration and NO production.

Risk Factors for Frequent Infections in Patients With Extremely Severe Motor and Intellectual Disabilities.

BACKGROUND: At our institution, patients of all ages with extremely severe motor and intellectual disabilities (ESMID) receive comprehensive management similar to intensive care for "extremely ill patients." Some patients with ESMID develop frequent infections that are difficult to manage. The purpose of this study was to identify risk factors for frequent infections in these patients. METHODS: Thirty-seven patients with ESMID who were treated for infections at our institution between September 2018 and August 2019 were retrospectively investigated. Frequent infection was defined as three or more episodes of infection and antimicrobial treatment in one year. Infection status and potential risk factors for frequent infections (patient background factors, severity score, hematological parameters, anthropometry index, and parenteral nutritional status) were examined in univariate and multivariate analyses. RESULTS: Frequent infections occurred in 11 of the 37 patients (29.7%) during the study period, including respiratory and urinary tract infections. Univariate and multivariate analyses suggested hypoalbuminemia (p<0.01) and hypertriglyceridemia (p<0.01) were independent risk factors for frequent infections. CONCLUSIONS: Hypoalbuminemia and hypertriglyceridemia may be risk factors for frequent infections in patients with ESMID.

Application and limitation of a biological clock-based method for estimating time of death in forensic practices.

Estimating time of death is one of the most important problems in forensics. Here, we evaluated the applicability, limitations and reliability of the developed biological clock-based method. We analyzed the expression of the clock genes, BMAL1 and NR1D1, in 318 dead hearts with defined time of death by real-time RT-PCR. For estimating the time of death, we chose two parameters, the NR1D1/BMAL1 ratio and BMAL1/NR1D1 ratio for morning and evening deaths, respectively. The NR1D1/BMAL1 ratio was significantly higher in morning deaths and the BMAL1/NR1D1 ratio was significantly higher in evening deaths. Sex, age, postmortem interval, and most causes of death had no significant effect on the two parameters, except for infants and the elderly, and severe brain injury. Although our method may not work in all cases, our method is useful for forensic practice in that it complements classical methods that are strongly influenced by the environment in which the corpse is placed. However, this method should be applied with caution in infants, the elderly, and patients with severe brain injury.

Forensic application of epidermal expression of HSP27 and HSP70 for the determination of wound vitality in human compressed neck skin.

Estimating the age and vitality of human skin wounds is essential in forensic practice, and the use of immunohistochemical parameters in this regard remains a challenge. Heat shock proteins (HSPs) are evolutionarily conserved universal proteins that protect biological systems from various types of stress. However, its importance in forensic pathology for determining wound activation in neck compression skin remains unclear. The expression of HSP27 and HSP70 in neck skin samples was immunohistochemically examined to understand its forensic applicability in determining wound vitality. Skin samples were obtained from 45 cases of neck compression (hanging, 32 cases; strangulation, 10 cases; manual strangulation, 2 cases; other, 1 case) during forensic autopsies; intact skin from the same individual was used as a control. HSP27 expression was detected in 17.4% of keratinocytes in the intact skin samples. In the compressed region, the frequency of HSP27 expression in keratinocytes was 75.8%, which was significantly higher than that in intact skin. Similarly, HSP70 expression was 24.8% in intact skin samples and 81.9% in compressed skin samples, significantly higher in compressed skin than in intact skin samples. This increase in case compression cases may be due to the cell defence role of HSPs. From a forensic pathology perspective, the immunohistochemical examination of HSP27 and HSP70 expression in neck skin could be considered a valuable marker for diagnosing traces of antemortem compression.

Inborn errors of bile acid metabolism in Japan.

Bile acids are a category of steroids biosynthesized from cholesterol in the liver. Inborn errors of their metabolism are inherited in an autosomal recessive manner, resulting in enzyme deficiencies affecting the bile acid biosynthetic pathway. These defects in the pathway cause accumulation of unusual bile acids or bile alcohols. Unusual bile acids are highly cytotoxic, causing injury to the liver. These unusual bile acids damage hepatocytes, resulting in cholestatic liver injury beginning in infancy. Except for cerebrotendinous xanthomatosis and some secondary defects, various inborn errors of bile acid metabolism (IEBAM) have been reported from Japan, affecting eight patients including three with 3ß-hydroxy-Δ5 -C27 -steroid dehydrogenase/isomerase deficiency, three with Δ4 -3-oxosteroid 5ß-reductase deficiency, one with oxysterol 7α-hydroxylase deficiency, and one with bile acid-CoA: amino acid N-acyltransferase deficiency. Distinctive laboratory findings in patients with 3ß-hydroxy-Δ5 -C27 -steroid dehydrogenase/isomerase deficiency, Δ4 -3-oxosteroid 5ß-reductase deficiency, and oxysterol 7α-hydroxylase deficiency include normal serum γ-glutamyltransferase and total bile acids concentrations despite presence of cholestasis (elevated serum direct bilirubin) from infancy. Pediatricians and pediatric surgeons who suspect a case of IEBAM should obtain urinary and serum bile acid analyses using gas or liquid chromatography-mass spectrometry as well as genetic analyses. Available treatments include oral cholic acid, chenodeoxycholic acid, glycocholic acid, and ursodeoxycholic acid; fat-soluble vitamin supplementation; and liver transplantation. Early diagnosis and treatment can offer a good outcome.

Macrophage polarity and wound age determination.

We investigated the dynamics of the gene expression of M1 and M2 macrophage markers during skin wound healing in mice. Expression of M1-macrophage markers, such as Il12a, Tnf, Il6, Il1b, and Nos2 was upregulated after wounding and peaked at 1 or 3 days after injury, and that of M2-macrophage markers such as Mrc1, Cd163, Ccl17, Arg, and Tgfb1, peaked at 6 days after injury. Consistent with these findings, using triple-color immunofluorescence analysis revealed that F4/80+CD80+ M1 macrophages were more abundant than F4/80+CD206+ M2 macrophages on day 3 in mouse wound specimens, and that M2 macrophages were prominently detected in day 6 wounds. For application in forensic practice, we examined macrophage polarization using human wound specimens. The average ratios of CD68+iNOS+ M1 macrophages to CD68+CD163+ M2 macrophages (M1/M2 ratios) were greater than 2.5 for the wounds aged 2-5 days. Out of 11 wounds aged 1-5 days, five samples had the M1/M2 ratios of > 3.0. These observations propose that the M1/M2 ratios of 3.0 would indicate a wound age of 1-5 days as the forensic opinion. This study showed that M1 and M2 macrophages in human skin wound might be a promising marker for wound age determination.

Forensic Application of Epidermal Ubiquitin Expression to Determination of Wound Vitality in Human Compressed Neck Skin.

Ubiquitin is a member of the heat shock protein family and is rapidly induced by various types of stimuli, including ischemic and mechanical stress. However, its significance in determining wound vitality of neck compression skin in forensic pathology remains unclear. We immunohistochemically examined the expression of ubiquitin in the neck skin samples to understand its forensic applicability in determining wound vitality. Skin samples were obtained from 53 cases of neck compression (hanging, 42 cases; strangulation, 11 cases) during forensic autopsies. Intact skin from the same individual was used as the control. Ubiquitin expression was detected in 73.9% of keratinocytes in intact skin samples, but only in 21.2% of keratinocytes in the compression regions, with statistical differences between the control and compression groups. This depletion in the case of neck compression may be caused by the impaired conversion of conjugated to free ubiquitin and failure of de novo ubiquitin synthesis. From a forensic pathological perspective, immunohistochemical examination of ubiquitin expression in the skin of the neck can be regarded as a valuable marker for diagnosing traces of antemortem compression.

ASP7266, a Novel Antibody against Human Thymic Stromal Lymphopoietin Receptor for the Treatment of Allergic Diseases.

Thymic stromal lymphopoietin (TSLP), positioned at the top of the inflammatory cascade, is a key regulator that enhances allergic inflammatory responses by activating T helper type 2 cells, Group 2 innate lymphoid cells (ILC2), and myeloid dendritic cells (mDCs) via the TSLP receptor (TSLPR). We evaluated the inhibitory effects of ASP7266, a novel recombinant fully human IgG1 monoclonal antibody against TSLPR, on TSLP signaling and inflammation. The inhibitory effects of ASP7266 and the control antibody tezepelumab on TSLP and TSLPR interactions were investigated using a proliferation assay with TSLP stimulation and a chemokine production assay. The pharmacological effects of ASP7266 were investigated by examining differentiation of naive CD4+ T cells, ILC2 cytokine production, and ascaris extract-induced skin allergic reaction in cynomolgus monkeys. ASP7266 potently inhibited TSLP-induced cell proliferation and C-C motif chemokine ligand 17 production. Furthermore, ASP7266 inhibited TSLP-stimulated mDC-mediated naive CD4+ T-cell differentiation and interleukin 5 production by lineage-negative peripheral blood mononuclear cells, which can be considered ILC2 in vitro. In sensitized monkeys, ASP7266 completely suppressed ascaris extract-induced allergic skin reactions. Based on these results, ASP7266, a novel human therapeutic antibody against TSLPR, is a potential therapy for patients with allergic diseases. SIGNIFICANCE STATEMENT: TSLP, positioned at the top of the inflammatory cascade, plays a key role in various allergic diseases, including asthma, chronic rhinosinusitis with nasal polyposis, and atopic dermatitis. Here we show that the anti-TSLPR antibody ASP7266 exhibited excellent pharmacological activity in preclinical studies. Therefore, ASP7266 has the potential to be a promising treatment option for patients with allergic disorders.

A case of necrotizing fasciitis following intra-articular injections - Iatrogenic or spontaneous?

Here, we report a case of necrotizing fasciitis following intra-articular injection of hyaluronic acid. A 73-year-old female received intra-articular injections of hyaluronic acid due to arthralgia at the left shoulder and knee, and was found dead in her living room at one day. At the forensic autopsy, injection marks with bullae and erythema were found at the left shoulder and knee and liquefactive necrosis of muscle tissues was observed in the left but not right extremities. Histopathological examinations of the left upper arm and thigh revealed severe rhabdomyolysis with lots of bacterial clusters. Bacteriological examinations detected group A Streptococcus from intracardiac blood and affected muscle tissues. Postmortem biochemical analysis of blood showed escalated blood urea nitrogen (133.8 mg/dL), creatinine (4.57 mg/dL) and C-reactive protein (45.0 mg/dL). The cause of her death was diagnosed as streptococcal toxic shock syndrome (STSS). Moreover, it was suggested that the injection was inappropriately conducted and served as a portal of bacterial entry.

Forensic significance of intracardiac heme oxygenase-1 expression in acute myocardial ischemia.

Heme oxygenase-1 (HO-1), an inducible stress-response protein, exerts anti-oxidant and anti-apoptotic effects. However, its significance in forensic diagnosis of acute ischemic heart diseases (AIHD) such as myocardial infarction (MI) is still unknown. We examined the immunohistochemical expression of HO-1 in the heart samples to discuss their forensic significance to determine acute cardiac ischemia. The heart samples were obtained from 23 AIHD cases and 33 non-AIHD cases as controls. HO-1 positive signals in cardiomyocyte nuclear were detected in 78.2% of AIHD cases, however, that were detected in only 24.2% control cases with statistical difference between AIHD and non-AIHD groups. In contrast to HO-1 protein expression, there was no significant difference in the appearance of myoglobin pallor regions and leukocyte infiltration in the hearts between AIHD and non-AIHD groups. From the viewpoints of forensic pathology, intracardiac HO-1 expression would be considered a valuable marker to diagnose AIHD as the cause of death.

Rotor Syndrome: Glucuronidated Bile Acidemia From Defective Reuptake by Hepatocytes.

Organic anion transporting polypeptide (OATP) 1B1 (gene, solute carrier organic anion transporter family member 1B1 [SLCO1B1]) and OATP1B3 (SLCO1B3) serve as transporters for hepatic uptake of important endogenous substances and several commonly prescribed drugs. Inactivation of both proteins together causes Rotor syndrome. How this OATP1B1/1B3 defect disturbs bile acid (BA) metabolism is largely unknown. In this study, we performed detailed BA analysis in 3 patients with genetically diagnosed Rotor syndrome. We found that BAs glucuronidated at the C-3 position (BA-3G) accounted for 50% or more of total BAs in these patients. In contrast but similarly to healthy controls, only trace amounts of BA-3G were detected in patients with constitutional indocyanine green excretory defect (OATP1B3 deficiency) or sodium-taurocholate cotransporting polypeptide (NTCP; gene, solute carrier family 10 member 1 [SLC10A1]) deficiency. Therefore, substantial amounts of BA-3G are synthesized in hepatocytes. The cycling pathway of BA-3G, consisting of excretion from upstream hepatocytes and uptake by downstream hepatocytes by OATP1B1/1B3 may exist to reduce the burden on upstream hepatocytes. Conclusion: Detailed BA analysis revealed glucuronidated bile acidemia in patients with Rotor syndrome. Further exploration of the physiologic role of glucuronidated BAs is necessary.

A Japanese prospective multicenter study of urinary oxysterols in biliary atresia.

Diagnosis of biliary atresia (BA) can involve uncertainties. In the present prospective multicenter study, we considered whether urinary oxysterols represent a useful marker for diagnosis of BA in Japanese children. Subjects under 6 months old at 7 pediatric centers in Japan were prospectively enrolled, including patients with cholestasis and healthy controls (HC) without liver disease. Patients with cholestasis constituted 2 groups representing BA patients and others with cholestasis from other causes (non-BA). We quantitatively analyzed 7 oxysterols including 4ß-, 20(S)-, 22(S)-, 22(R)-, 24(S)-, 25-, and 27-hydroxycholesterol by liquid chromatography/electrospray ionization-tandem mass spectrometry. Enrolled subjects included 14 with BA (median age 68 days; range 26-170) and 10 non-BA cholestatic controls (59; 14-162), as well as 10 HC (57; 25-120). Total urinary oxysterols were significantly greater in BA (median, 153.0 µmol/mol creatinine; range 24.1-486.7; P < 0.001) and non-BA (36.2; 5.8-411.3; P < 0.05) than in HC (2.7; 0.8-7.6). In patients with BA, urinary 27-hydroxycholesterol (3.61; 0.42-11.09; P < 0.01) was significantly greater than in non-BA (0.71; 0-5.62). In receiver operating characteristic (ROC) curve analysis for distinguishing BA from non-BA, the area under the ROC curve for urinary 27-hydroxycholesterol was 0.83. In conclusion, this first report of urinary oxysterol analysis in patients with BA indicated that 27-hydroxycholesterol may be a useful marker for distinguishing BA from other causes of neonatal cholestasis.

Bile Acid Synthesis Disorders in Japan: Long-Term Outcome and Chenodeoxycholic Acid Treatment.

BACKGROUND: We encountered 7 Japanese patients with bile acid synthesis disorders (BASD) including 3ß-hydroxy-Δ5-C27-steroid dehydrogenase/isomerase (3ß-HSD) deficiency (n = 3), Δ4-3-oxosteroid 5ß-reductase (5ß-reductase) deficiency (n = 3), and oxysterol 7α-hydroxylase deficiency (n = 1) over 21 years between 1996 and 2017. AIM: We aimed to clarify long-term outcome in the 7 patients with BASD as well as long-term efficacy of chenodeoxycholic acid (CDCA) treatment in the 5 patients with 3ß-HSD deficiency or 5ß-reductase deficiency. METHODS: Diagnoses were made from bile acid and genetic analyses. Bile acid analysis in serum and urine was performed using gas chromatography-mass spectrometry. Clinical and laboratory findings and bile acid profiles at diagnosis and most recent visit were retrospectively obtained from medical records. Long-term outcome included follow-up duration, treatments, growth, education/employment, complications of treatment, and other problems. RESULTS: Medians with ranges of current patient ages and duration of CDCA treatment are 10 years (8 to 43) and 10 years (8 to 21), respectively. All 7 patients, who had homozygous or compound heterozygous mutations in the HSD3B7, SRD5B1, or CYP7B1 gene, are currently in good health without liver dysfunction. In the 5 patients with CDCA treatment, hepatic function gradually improved following initiation. No adverse effects were noted. CONCLUSIONS: We concluded that CDCA treatment is effective in 3ß-HSD deficiency and 5ß-reductase deficiency, as cholic acid has been in other countries. BASD carry a good prognosis following early diagnosis and initiation of long-term CDCA treatment.

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.

Complete decapitation by a self-constructed guillotine in a burned body - complex suicide or postmortem burning?

We report a suicide case of complete decapitation using a self-constructed guillotine. A 45-year-old man, whose body was severely burned, was found dead. The head was completely separated from the middle level of the neck, and a sharp blade with a steel frame was placed between the head and neck. The severance plane passed between the C4 and C5 vertebrae. Vital reactions such as hemorrhage could not be confirmed at the decapitated skin edge because the body was severely burned. Both common carotid arteries were sharply transected. Subendocardial hemorrhage was detected in the left ventricle. Only a little blood, but no soot, was detected in the respiratory tract, including the trachea and bilateral bronchi. Subarachnoid hemorrhage was noted at the edge of the cervical spinal cord. The saturation level of CO-Hb was 5.7% in the left cardiac blood, 5.9% in the right cardiac blood, and 5.8% in the peripheral blood from the femoral vein. Cervical transection was diagnosed as the cause of death. We believe that he was unintentionally burned by spread fire from an automobile after decapitation by a self-constructed guillotine.