Estimation of population affinity using proximal femoral measurements based on computed tomographic images in the Japanese and western Australian populations

The present study analyzes morphological differences femora of contemporary Japanese and Western Australian individuals and investigates the feasibility of population affinity estimation based on computed tomographic (CT) data. The latter is deemed to be of practical importance because most anthropological methods rely on the assessment of aspects of skull morphology, which when damaged and/or unavailable, often hampers attempts to estimate population affinity. The study sample comprised CT scans of 297 (146 females; 151 males) Japanese and 330 (145 females; 185 males) Western Australian adult individuals. A total of 10 measurements were acquired in two-dimensional CT images of the left and right femora; two machine learning methods (random forest modeling [RFM]) and support vector machine [SVM]) were then applied for population affinity classification. The accuracy of the two-way (sex-specific and sex-mixed) model was between 71.38 and 82.07% and 76.09-86.09% for RFM and SVM, respectively. Sex-specific (female and male) models were slightly more accurate compared to the sex-mixed models; there were no considerable differences in the correct classification rates between the female- and male-specific models. All the classification accuracies were higher in the Western Australian population, except for the male model using SVM. The four-way sex and population affinity model had an overall classification accuracy of 74.96% and 79.11% for RFM and SVM, respectively. The Western Australian females had the lowest correct classification rate followed by the Japanese males. Our data indicate that femoral measurements may be particularly useful for classification of Japanese and Western Australian individuals.

Lethal hemopericardium caused by infection of mitral annular calcification: An autopsy case report

Mitral annular calcification (MAC) is a chronic and degenerative condition involving calcification of the mitral annulus. MAC is a risk factor for coronary artery disease, cardiovascular events, stroke, and cardiovascular death. However, patients with MAC are often asymptomatic. Herein, we present the first case of cardiac tamponade due to infection of MAC in forensic pathology. An 80-year-old woman was found in cardiopulmonary arrest shortly after experiencing fatigue. She was transferred to a hospital, and despite chest compression and ventilation, she was pronounced dead due to no response. Postmortem computed tomography, autopsy, and histological examination showed MAC, abscess formation involving Gram-positive cocci on the MAC, and fistulation of the abscess into the intracardial pericardial cavities, resulting in a massive lethal hemopericardium.

Estimation of ancestry from cranial measurements based on MDCT data acquired in a Japanese and Western Australian population

The estimation of ancestry is important not only towards establishing identity but also as a required precursor to facilitating the accurate estimation of other attributes such as sex, age at death, and stature. The present study aims to analyze morphological variation in the crania of Japanese and Western Australian individuals and test predictive models based on machine learning for their potential forensic application. The Japanese and Western Australian samples comprise computed tomography (CT) scans of 230 (111 female; 119 male) and 225 adult individuals (112 female; 113 male), respectively. A total of 18 measurements were calculated, and machine learning methods (random forest modeling, RFM; support vector machine, SVM) were used to classify ancestry. The two-way unisex model achieved an overall accuracy of 93.2% for RFM and 97.1% for SVM, respectively. The four-way sex and ancestry model demonstrated an overall classification accuracy of 84.0% for RFM and 93.0% for SVM. The sex-specific models were most accurate in the female samples (♀ 95.1% for RFM and 100% for SVM; ♂91.4% for RFM and 97.4% for SVM). Our findings suggest that cranial measurements acquired in CT images can be used to accurately classify Japanese and Western Australian individuals into their respective population. This is the first study to assess the feasibility of ancestry estimation using three-dimensional CT images of the skull.

Evaluation of organophosphorus pesticide tyrosine adducts for postmortem change by human serum albumin with liquid chromatography quadrupole Orbitrap mass spectrometry

Organophosphorus pesticides (OPPs) having a phosphate ester moiety, such as malathion (MA) and methidathion (DMTP), are widely used and have been detected in many fatal cases of accidental exposure or suicide in Japan. In forensic toxicology, the accurate determination of blood OPP concentration is mandatory to prove death by OPP poisoning. However, fatal pesticide concentration in blood at autopsy varies depending on the circumstances surrounding the dead body. In this study, we found that 16 OPPs were degraded by human serum albumin (HSA) in a temperature-dependent fashion. The mechanism underlying MA, DMTP, azinphos-methyl, etrimfos, fenthion (MPP), pirimiphos-methyl, (E)-dimethylvinphos, (Z)-dimethylvinphos, vamidothion, edifenphos (EDDP), fosthiazate, and pyraclofos degradation involves the formation of adducts with tyrosine residues in HSA. The mass spectra obtained by liquid chromatography quadrupole Orbitrap mass spectrometry revealed that phosphate ester amino acid adducts such as Y-adduct1, Y-adduct2, Y-adduct3, Y-adduct4, and Y-adduct5 were formed in HSA solution incubated with OPPs. These results indicate that the 16 OPPs are postmortem changed by HSA. The detection of phosphate ester amino acid adducts such as Y-adduct1, Y-adduct2, Y-adduct3, Y-adduct4, and Y-adduct5, instead of MA, DMTP, azinphos-methyl, etrimfos, MPP, pirimiphos-methyl, (E)-dimethylvinphos, (Z)-dimethylvinphos, vamidothion, EDDP, fosthiazate, and pyraclofos per se, may be used to determine death by these OPPs poisoning.

Mandibular torus thickness associated with age: Postmortem computed tomographic analysis

Age estimation is an essential step in identifying human corpses. Several mandibular landmarks have been highlighted as skeletal sites for age estimation since aging causes morphological changes. Reports suggest that mandibular torus size may be associated with aging; however, thorough investigation has not been performed owing to the difficulty in measuring it. Therefore, this study aimed to determine the association between age and mandibular torus thickness using postmortem computed tomography data from Japanese corpses. This study included 2,792 corpses with mean (standard deviation) age of 58.0 (22.4) years (range, 0-101 years) and 67.6 % males. Further, 2,662 (95.3 %), 14 (0.5 %), 59 (2.1 %), and 57 (2.0 %) corpses were in the permanent, mixed, primary, and predental dentition periods, respectively. Multivariable analysis was performed to quantify the impact of age on mandibular torus thickness, adjusting for sex, height, weight, and occlusal contact status. The model also included an interaction term between age and occlusal status because of the potential effect modification by occlusion. Results of the multivariable regression analysis showed that mandibular torus thickness increased with age (the regression coefficients (95 % confidence interval) were 0.6 (0.2-1.0), 0.7 (0.3-1.0), 1.0 (0.6-1.4), 1.3 (0.9-1.7), 1.3 (0.8-1.8), and 1.1 (0.4-1.7) for age groups 30-39, 40-49, 50-59, 60-69, 70-79, and 80-89 years, respectively), especially in males with occlusal contact. A significant association between mandibular torus thickness and age, modified by occlusal status and sex, was identified. Therefore, data regarding the thickness of the mandibular torus and occlusal status may be useful for age estimation in human corpses.

A Descriptive Study of the Characteristics of Homicide-Suicide in Forensic Autopsy Cases

Homicide followed by suicide (HS) is a tragic event with varied characteristics across countries and regions. Compared to Western countries, there are limited studies on HS in Asian countries. Therefore, this study aimed to clarify the characteristics of recent HS cases by examining forensic autopsy records from 2008 to 2020 collected from the Department of Legal Medicine, Chiba University, in Japan. A total of 77 HS cases were identified, involving 77 perpetrators (52 completed suicides, 25 attempted suicides), with 28 perpetrator and 89 victim autopsies. Our findings showed that older adults accounted for nearly half of the victims; victims were mostly females, whereas most perpetrators were male. The most common HS relationship was that between a parent and a child. Autopsy findings showed that the most common cause of death was strangulation, and illegal drugs were detected only in a few cases; however, psychotropic drugs were detected in child victims. No obvious evidence of past child physical abuse by caregivers was found. In contrast, intimate partner violence (IPV) was present, with a history of IPV found in half of HS cases involving adult intimate partner relationships. Notably, gender differences in age and relationship to the victim were identified. Likewise, some perpetrators may have expressed their plans and intentions for HS before the event, which may represent an important sign for HS prevention. However, to accurately reveal the course of HS, nationwide integrated statistics, forensic autopsies, including toxicological analyses of the deceased; and forensic psychiatric perspectives, including psychological autopsy, are required.

Forensic application of three interstitial pneumonia markers: search for new pneumonia markers in dead bodies

In forensic cases, detailed identification of pneumonia is important. Our objective was to statistically determine the applicability of three interstitial lung disease (ILD) markers for forensic diagnosis using serum collected from dead bodies with various postmortem intervals (PMIs). We retrospectively analyzed the levels of postmortem serum Krebs von den Lungen-6 (KL-6) and pulmonary surfactant-associated proteins A and D (SP-A and SP-D) using 221 samples obtained during forensic autopsy at our facility from 2019 to 2023. We evaluated the diagnostic efficacy of ILD markers for various pneumonias against the pathological diagnosis, and examined the assessment of the severity of ILD. When comparing the ILD group with bacterial pneumonia (BP) versus the control group, there was a significant increase in KL-6 in the ILD group. When comparing the severe ILD (SILD) group with the mild ILD (MILD) group, there was a significant increase in KL-6 and SP-D in the SILD group. The optimal cutoff values for differentiating SILD were 607.0 U/mL for KL-6, 55.5 ng/mL for SP-A, and 160.0 ng/mL for SP-D, and the sensitivity/specificity (%) of KL-6, SP-A, and SP-D for SILD were 84.1/95.2, 55.6/85.7, and 66.7/74.6, respectively. This is the first study to examine KL-6 in postmortem serum in forensic medicine. By analyzing dead bodies with various PMIs, our results confirmed statistically that postmortem serum KL-6 specifically detects ILD, postmortem serum SP-A has high sensitivity to lung injury, and postmortem serum SP-D is potentially useful in assessing the severity of ILD.

Population affinity estimation using pelvic measurements based on computed tomographic data acquired from Japanese and Western Australian populations

The present study analyzes morphological differences in the pelvis of Japanese and Western Australian individuals and investigates the feasibility of population affinity classification based on computed tomography (CT) data. The Japanese and Western Australian samples comprise CT scans of 207 (103 females; 104 males) and 158 (78 females; 80 males) adult individuals, respectively. Following volumetric reconstruction, a total of 19 pelvic landmarks were obtained on each sample, and 11 measurements, including two angles, were calculated. Machine learning methods (random forest modeling [RFM] and support vector machine [SVM]) were used to classify population affinity. Classification accuracy of the two-way models was approximately 80% for RFM: the two-way sex-specific and sex-mixed models for SVM achieved > 90% and > 85%, respectively. The sex-specific models had higher accurate classification rates than the sex-mixed models, except for the Japanese male sample. The classification accuracy of the four-way sex and population affinity model had an overall classification accuracy of 76.71% for RFM and 87.67% for SVM. All the correct classification rates were higher in the Japanese relative to the Western Australian sample. Our data suggest that pelvic morphology is sufficiently distinct between Japanese and Western Australian individuals to facilitate the accurate classification of population affinity based on measurements acquired in CT images. To the best of our knowledge, this is the first study investigating the feasibility of population affinity estimation based on CT images of the pelvis, which appears as a viable supplement to traditional approaches based on cranio-facial morphology.

Detection of diatoms in a case of mud aspiration at a coastal area

The source of diatoms detected in non-drowned bodies have been attributed to postmortem invasion, contamination during autopsy or diatom testing, or "natural load." However, sand aspiration has not been reported as a source. Herein, we report an autopsy case in which diatoms were detected in a non-drowned human who had aspirated mud. A man in his 60 s was found dead at a harbor park in Japan. His whole body was covered with sand, including his face. A situational investigation suggested that he may have entered the sea. Autopsy revealed intratracheal mud, with no obvious findings indicating drowning, suggesting that he died from mud aspiration probably due to hypothermia or non-lethal ethanol intoxication. In the diatom test, 10-100 diatoms/g were detected in bilateral lung samples, which were similar to those found in the intraoral and intratracheal mud and the sand samples from around the discovery site and not similar to those found in the seawater samples. The diatoms in the stomach content exhibited an intermediate trend between those found in the sand and seawater. Therefore, careful qualitative and quantitative analyses are required to differentiate between true drowning and false-positives in non-drowning cases to determine the cause of death.

Estimation of missing mandible from the skull using postmortem CT images

Skeletal remains often have missing mandibles owing to the environment in which the corpse was placed or damage caused by an animal. Loss of the mandible reduces the accuracy of skull identification. Although several studies have validated methods for estimating mandibular morphology from conventional anthropological measurements using skull specimens, there are no reports using three-dimensional computed tomography (3DCT) images. Here, we examined methods for establishing the mandibular morphology from the remaining skulls using postmortem computed tomography (PMCT) images. We used PMCT images from 200 Japanese subjects as samples. After verifying the morphological correlation between the cranium and mandible, we created and validated estimation models using multiple regression analysis (stepwise method) for seven sites that were necessary for understanding the morphology of the mandible. Among the regression models, the estimated model for bicondylar breadth had the highest coefficient of determination (adjR2 = 0.53). We verified the accuracy of the model on a sample independent from the specimen used to create the estimation model and found that the formulated model of bicondylar breadth had good estimation accuracy, with a high correlation coefficient between the measured and predicted values of 0.82 and a mean absolute error of 3.582 mm, indicating that the model had good estimation accuracy. Here, we established a novel method for estimating the missing mandibular morphology based on PMCT data from the Japanese population. Our estimation model can help determine the missing mandibular morphology in a cranium remnant.

Usefulness of powdered crown of mandibular first premolars in birth year estimation by radiocarbon dating

BACKGROUND

Radiocarbon (14C), whose levels increased in the atmosphere between 1955 and 1963, accumulates in the enamel of human teeth only during the process of tooth formation and has been applied to estimate the birth year of unidentified corpses. However, enamel isolation from teeth is time-consuming and labor-intensive. Therefore, this study aimed to estimate the birth year using 14C in the crown of a single mandibular first premolar tooth.

MATERIALS AND METHODS

Fourteen mandibular first premolars collected from forensic autopsies were analyzed. For nine teeth, each tooth was cut longitudinally: half of the tooth was enamel, and the other half was crown (1). For the other five teeth, the entire crown was used (2). Thereafter, the 14C concentration in each tooth was measured using accelerator mass spectrometry.

RESULTS

The absolute error between the actual date of birth (DOB) and the estimated DOB was within the range of 1.0-8.8 years in the enamel of five teeth and 0.1-4.0 years in the crown halves of seven teeth (1). For the five teeth with entire crowns, the absolute errors ranged between 0.3 and 3.0 years (2).

CONCLUSION

The absolute error of 14C-based year of birth estimation using the powdered crown of the mandibular first premolar teeth ranged between 0.1 and 4.0 years. Our method, which involves pulverizing an entire crown, eliminates the need for the equipment, time, and labor associated with enamel isolation. Therefore, 14C dating using powdered crowns of mandibular premolars can be useful for birth year estimation.

Two medicolegal autopsy cases of multinodular and vacuolating neuronal tumor revealed by postmortem MRI

The multinodular and vacuolating neuronal tumor (MVNT) is a recently recognized brain lesion. MVNT has a characteristic appearance in MRI images and is potentially epileptogenic. To the best of our knowledge, no report has yet described this pathological entity in the forensic medicine literature. We present two medicolegal autopsy cases where postmortem MRI (PMMR) was useful to detect this lesion. Case 1: a man in his 30s, with about a 7-year history of intractable epilepsy and known MVNT died suddenly. Although MVNT was not detected in the initial morphological evaluation during autopsy, PMMR of the formalin-fixed brain revealed the lesion in the left frontal lobe. Histopathology confirmed it as a MVNT. Case 2: a man in his 20s hanged himself to death. PMMR prior to autopsy revealed MVNT in his brain, and the diagnosis was confirmed by a detailed histopathological evaluation. In both cases, postmortem CT was not useful for evaluation. The cases suggested that MVNT can cause sudden, unexpected epileptic death, and pre- or post-autopsy PMMR may be useful to detect it.

COVID-19 Analysis in Tissue Samples Acquired by Minimally Invasive Autopsy in Out-of-Hospital Deaths with Postmortem Degeneration

Minimally invasive autopsy (MIA) is an alternative to a full autopsy for the collection of tissue samples from patients' bodies using instruments such as a biopsy needle. MIA has been conducted in many cases of coronavirus disease 2019 (COVID-19) and has contributed to the elucidation of the disease pathogenesis. However, most cases analyzed are hospital deaths, and there are few reports on the application of MIA in out-of-hospital deaths with varying extents of post-mortem changes. In this study, MIA and autopsies were performed in 15 patients with COVID-19 2-30 days after death, including 11 out-of-hospital deaths. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome detection by reverse transcriptase quantitative polymerase chain reaction using MIA samples was mostly consistent with autopsy samples, particularly lung tissue, even in out-of-hospital cases. MIA had high sensitivity and specificity (> 0.80). Histological examination of lung tissue obtained by MIA showed characteristics of COVID-19 pneumonia, with 91% agreement with autopsy samples, whereas localization of SARS-CoV-2 protein in lung tissue was indicated by immunohistochemistry, with 75% agreement. In conclusion, these results suggest that MIA is applicable to out-of-hospital deaths due to COVID-19 with various postmortem changes, especially when autopsies are not available.

Genomic analysis of SARS-CoV-2 in forensic autopsy cases of COVID-19

Numerous genomic analyses of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been conducted, highlighting its variations and lineage transitions. Despite the importance of forensic autopsy in investigating deaths due to coronavirus disease 2019 (COVID-19), including out-of-hospital deaths, viral genomic analysis has rarely been reported due in part to postmortem changes. In this study, various specimens were collected from 18 forensic autopsy cases with SARS-CoV-2 infection. Reverse-transcription quantitative polymerase chain reaction revealed the distribution of the virus in the body, primarily in the respiratory organs. Next-generation sequencing determined the complete genome sequences in 15 of the 18 cases, although some cases showed severe postmortem changes or degradation of tissue RNA. Intrahost genomic diversity of the virus was identified in one case of death due to COVID-19. The accumulation of single-nucleotide variations in the lung of the case suggested the intrahost evolution of SARS-CoV-2. Lung of the case showed diffuse alveolar damage histologically and positivity for SARS-CoV-2 by immunohistochemical analysis and in situ hybridization, indicating virus-associated pneumonia. This study provides insights into the feasibility of genomic analysis of SARS-CoV-2 in forensic autopsy cases and the potential for uncovering important information in COVID-19 deaths, including out-of-hospital deaths.

Identification of post-mortem paliperidone metabolite in human blood by LC-Q-Orbitrap-MS

Paliperidone is a widely used antipsychotic agent detected in many fatal intoxications and suicide cases. In forensic toxicology, the accurate determination of blood paliperidone concentrations is required to prove death by paliperidone poisoning. However, the lethal concentration of paliperidone in blood at autopsy differs from that at the time of death. In this study, we found that paliperidone was decomposed by hemoglobin (Hb) through the Fenton reaction in a temperature-dependent fashion. The mechanism underlying paliperidone decomposition involves the cleavage of its C-N bond linker moiety. The mass spectra obtained by liquid chromatography quadrupole orbitrap mass spectrometry (LC-Q-Orbitrap-MS) revealed the formation of 6-fluoro-3-(4-piperidinyl)benzisoxazole (PM1) in Hb/H2O2 solution incubated with paliperidone, as well as in the blood of individuals who died from intentional ingestion of paliperidone. These results suggest that PM1 is the only metabolite produced from paliperidone as a result of temperature-dependent, post-mortem changes induced by Hb via the Fenton reaction, and may be useful as a biomarker to correct for the concentration of paliperidone in blood at the time of death in clinical cases.

Age estimation by palatal suture using modified Kamijo's method

The present study aimed to investigate the correlation between palatal suture obliteration and age in modern Japanese and to develop an age estimation equation by modifying Kamijo's (1949) method. The subjects were 195 Japanese skeletal remains (155 males and 40 females) whose age and sex were known. First, obliteration score (OS) was obtained by measuring palatal suture obliteration from photographic images taken at the time of forensic autopsy, and the correlation with age was examined; no significant correlation was found in females. Second, the palatal sutures were divided into 14 sections, and each section was scored from 0 to 4 points according to the degree of the suture obliteration. Suture scores (SS) were then calculated for each of the four sutures, and the sum of the 14 scores (TSS: total suture score) was used to perform regression analysis for age. For male and all subjects (male and female), age significantly increased (p < 0.001) according to increment of SSs for all sutures. TSS has the highest regression coefficient (r = 0.540), and the lowest standard error of estimation (13.54 years) for all of the patients. The intra- and inter-observer agreement scoring showed high reliability. Validation study using the formulae showed a high percentage of correct responses (80 %). In conclusion, age estimation regression formula by palatal suture using modified Kamijo's method was established for Japanese population, and the study showed the formula might be valid for age estimation.

Age estimation by evaluating median palatine suture closure using postmortem CT

This study sought to develop an age-estimation formula to evaluate the extent of median palatine suture (MP) closure using postmortem computed tomographic (PMCT) images. The PMCT images of 634 Japanese subjects (mean age, 54.5 years; standard deviation [SD], 23.2 years) with known age and sex were examined. The degree of suture closure of the MP, anterior median palatine suture (AMP), and posterior median palatine suture (PMP) was measured and scored (suture closure score, SCS), and a single linear regression analysis was conducted with age at death. On the analysis, SCS of MP, AMP, and PMP showed a significant correlation with age (p < 0.001). The correlation coefficient of MP was higher (0.760, male; 0.803, female; and 0.779, total) than that of AMP (0.726, male; 0.745, female; and 0.735, total) or PMP (0.457, male; 0.630, female; and 0.549, total). The regression formula and standard error of estimation (SEE) of MP were calculated as Age = 100.95 × SCS + 20.51 (SEE 14.87 years) for male subjects, Age = 91.93 × SCS + 26.65 (SEE 14.12 years) for female subjects, and Age = 95.17 × SCS + 24.09 (SEE 14.59 years) for the total, respectively. In addition, another 50 Japanese subjects were randomly selected to validate the age-estimation formula. In this validation, the actual age of 36 subjects (72%) was within the estimated age ± SEE. This study showed that the age estimation formula using PMCT images of MPs was potentially useful for estimating the age of unidentified corpses.

X-ray analytic microscopy with CT-guided sample extraction to analyze potential projectile fragments in a dead serow

In forensic pathology, it is important to detect and recover as evidence residual metal particles and projectiles when evaluating potential gunshot wounds. This process can be challenging when the bullets are fragmented. This report presents our experience using multiple modalities to analyze the wound of an illegally killed Japanese serow (Capricornis crispus) found in a mountainous region without its head and hind limbs. We performed postmortem computed tomography (PMCT) and necropsy that showed a distant-range gunshot wound of the neck likely created by a centerfire rifle. A postmortem cut through the neck and absent head precluded a complete evaluation. To determine the composition of the metal-like fragments in the neck, sampling and metal analysis were performed in two ways. Samples extracted from the exposed wound surface without CT guidance were analyzed directly using inductively coupled plasma mass spectrometry (ICP-MS). Samples from the bone, muscles, and cervical cord extracted under CT guidance were analyzed using x-ray analytic microscopy (XGT-9000, HORIBA, Kyoto, Japan). In wound surface samples, silicon and iron were detected as the main components on ICP-MS, suggesting that the materials were gravel. The samples taken under CT guidance and analyzed with XGT-9000 revealed that the high-density CT areas were mainly composed of lead. Combining CT-guided sample extraction and XGT-9000 can be useful for retrieving true projectile fragments and avoiding the confusion created by erroneously sampling non-projectile surface materials.

High titers of infectious SARS-CoV-2 in corpses of patients with COVID-19

OBJECTIVES

The prolonged presence of infectious SARS-CoV-2 in deceased patients with COVID-19 has been reported. However, infectious virus titers have not been determined. Such information is important for public health, death investigation, and handling corpses. The aim of this study was to assess the level of SARS-CoV-2 infectivity in the corpses of patients with COVID-19.

METHODS

We collected 11 nasopharyngeal swabs and 19 lung tissue specimens from 11 autopsy cases with COVID-19 in 2021. We then investigated the viral genomic copy number by real-time reverse transcription-polymerase chain reaction and infectious titers by cell culture and virus isolation.

RESULTS

Infectious virus was present in six of 11 (55%) cases, four of 11 (36%) nasopharyngeal swabs, and nine of 19 (47%) lung specimens. The virus titers ranged from 6.00E + 01 plaque-forming units/ml to 2.09E + 06 plaque-forming units/g. In all cases in which an infectious virus was found, the time from death to discovery was within 1 day and the longest postmortem interval was 13 days.

CONCLUSION

The corpses of patients with COVID-19 may have high titers of infectious virus after a long postmortem interval (up to 13 days). Therefore, appropriate infection control measures must be taken when handling corpses.

Statistical analysis of biomechanical properties and size of the sternum and its fracture risk in a Japanese sample

OBJECTIVE

Sternal fractures can have life-threatening complications. To understand chest injury mechanisms, sufficient data regarding the mechanical properties and structure of the sternum are required. The aim of this study was to examine the mechanical properties and size of the sternum in a Japanese forensic sample.

MATERIALS AND METHODS

Sterna were obtained from 120 Japanese dead bodies of known age and sex. The sample thickness (ST) and the sample width (SW) were measured using a computed tomographic image. Three-point-bending tests were conducted using a three-point-bending apparatus to assess the fracture load (FL) of the sample. Then, the flexural strength (FS) was calculated and the natural logarithm of FL (ln FL) and FS (ln FS) were also calculated.

RESULTS

The values of ST, ln FL, and ln FS for male samples were significantly greater than those for female samples. Both ln FL and ln FS had significant negative correlations with age regardless of sex; the Pearson product-moment correlation coefficients were larger for female samples than for male samples. Although age was significantly negatively correlated with SW in female samples, there was no significant correlation between age and SW in male samples. No significant correlations were found between age and ST regardless of sex.

CONCLUSION

This is the first study to present quantitative data on the biomechanical properties of the sternum. Because of the smaller sternal strength of elderly women, it is especially important for them to avoid the risk of sternal fractures.

Impact of the COVID-19 pandemic on pathological autopsy practices in Japan

During the coronavirus disease 2019 (COVID-19) pandemic, autopsies have provided valuable insights into the pathogenesis of COVID-19. The precise effect of this pandemic on autopsy procedures in Japan, especially in instances unrelated to COVID-19, has not yet been established. Therefore, we conducted a questionnaire survey from December 2020 to January 2021 regarding the status of pathological autopsy practices in Japan during the first year of the COVID-19 pandemic. The questionnaire was sent to 678 medical facilities with pathologists, of which 227 responded. In cases where a confirmed diagnosis of COVID-19 was not made at the time of autopsy, many facilities counted them as suspected COVID-19 cases if pneumonia was suspected clinically. At around half of the sites, autopsies were prohibited for suspected COVID-19 cases. In addition, the number of autopsies of non-COVID-19 cases during the pandemic period was also investigated, and a significant decrease was observed compared with the incidence in the pre-pandemic period. The COVID-19 pandemic has affected not only the autopsies of COVID-19 cases but also the entire practice of pathological autopsies. It is necessary to establish a system that supports the implementation of pathological autopsy practices during the pandemic of an emerging infectious disease.

Statistical analysis of the thickness and biomechanical properties of Japanese children's skulls

OBJECTIVE

The structure and strength of a child's skull are important in accurately determining what and how external forces were applied when examining head injuries. The aims of this study were to measure skull thickness and strength in children, evaluate sex differences, and investigate the correlation between skull thickness and strength and age.

MATERIALS AND METHODS

Skulls were obtained from 42 Japanese dead bodies under 20 years of age. During the autopsies, bone samples were taken from each skull. The length, width, and central thickness of the skulls were measured using calipers. Three-point bending tests were conducted, and bending load and displacement were recorded. Bending stress and bending strain were calculated, and Young's modulus, 0.2% proof stress, and maximum stress were obtained.

RESULTS

In cases under 1.5 years old, 14 out of 46 male samples and 20 out of 40 female samples did not fracture during the three-point bending test, though no significant sex differences were detected. No significant differences in age, sample thickness, Young's modulus, 0.2% proof stress, or maximum stress were detected between the sexes. The sample thickness, Young's modulus, 0.2% proof stress, and maximum stress increased significantly and logarithmically with age (R² = 0.761-0.899). Although age correlated with thickness, Young's modulus, and maximum stress more in females than in males, 0.2% proof stress correlated slightly better in males than in females.

CONCLUSION

The skulls of preschool children, in particular, are thin, have low strength, and are at high risk of fracturing even with relatively small external forces. Unlike adults, no significant sex differences in skull thickness or strength were observed in children.

Identification, measurement, and evaluation of blood concentrations of insulin glargine and insulin lispro by UPLC-MS-MS in a dead body suspected of insulin overdose

Insulin preparations, which are drug treatments for diabetes, cause fatal hypoglycemia when an overdose is administered. Cases of homicide and suicide using these preparations have been reported and are of great forensic interest. However, there are few reports assessing the postmortem concentration of insulin preparations, and it is often difficult to determine the cause of death. In the present study, we report a case of a suspected insulin glargine and insulin lispro overdose for suicide. A woman in her 30s had a history of mental illness and diabetes. The day before her death, she reported to her boyfriend that she had taken large doses of insulin preparations and prescription drugs. An autopsy revealed no fatal injuries or lesions. Drug screening tests revealed several prescription drugs, none of which showed toxic concentrations. Analysis using LC-MS/MS detected insulin glargine in the peripheral and cardiac blood at 429 μU/mL and 1362 μU/mL, respectively, whereas insulin lispro was detected in both the peripheral and cardiac blood at levels below the lower limit of quantification (LLOQ; <50 μU/mL). The cause of death was considered likely to be hypoglycemia caused by an overdose of insulin glargine. Insulin glargine is rapidly metabolized after subcutaneous administration and is rarely detected in the blood when used at therapeutic doses. There are no other reports on the quantification of insulin glargine parent compounds in postmortem samples, and this case provides important data on postmortem blood concentrations of insulin glargine intoxication.

Relevance of diatom testing on closed organs of a drowned cadaver who died after receiving treatment for 10 days: A case report

A male in his late adolescence fell into the sea and was found 50 min later with cardiopulmonary arrest. He was revived approximately 260 min after he drowned. Although he received several treatments, including venoarterial extracorporeal membrane oxygenation and continuous hemodiafiltration, he was clinically diagnosed with brain death. He died 10 days after the accident. The autopsy did not reveal any unremarkable findings other than those associated with post-resuscitation changes and medical treatment. The diatom test revealed 47.9, 311.6, and 577.5 diatom particles per gram from water, left lung, and right lung samples, respectively. No diatoms were detected in a 10 g liver sample, and 1 diatom was detected in each of approximately 12 g of bilateral kidney samples, which was different from the abundant species in the lung samples. The diatom test of the closed organs could be considered false negative for confirming drowning death since diatoms can also be detected in non-drowned cadavers on dry land. This suggests that diatoms might not reach the closed organs via circulation and that the diatom test of closed organ samples might no longer be necessary to confirm drowning deaths.

Increased Myosin light chain 9 expression during Kawasaki disease vasculitis

Introduction

Kawasaki disease (KD) is an acute systemic vasculitis that predominantly afflicts children. KD development is known to be associated with an aberrant immune response and abnormal platelet activation, however its etiology is still largely unknown. Myosin light chain 9 (Myl9) is known to regulate cellular contractility of both non-muscle and smooth muscle cells, and can be released from platelets, whereas any relations of Myl9 expression to KD vasculitis have not been examined.

Methods

Plasma Myl9 concentrations in KD patients and children with febrile illness were measured and associated with KD clinical course and prognosis. Myl9 release from platelets in KD patients was also evaluated in vitro. Myl9 expression was determined in coronary arteries from Lactobacillus casei cell wall extract (LCWE)-injected mice that develop experimental KD vasculitis, as well as in cardiac tissues obtained at autopsy from KD patients.

Results and discussion

Plasma Myl9 levels were significantly higher in KD patients during the acute phase compared with healthy controls or patients with other febrile illnesses, declined following IVIG therapy in IVIG-responders but not in non-responders. In vitro, platelets from KD patients released Myl9 independently of thrombin stimulation. In the LCWE-injected mice, Myl9 was detected in cardiac tissue at an early stage before inflammatory cell infiltration was observed. In tissues obtained at autopsy from KD patients, the highest Myl9 expression was observed in thrombi during the acute phase and in the intima and adventitia of coronary arteries during the chronic phase. Thus, our studies show that Myl9 expression is significantly increased during KD vasculitis and that Myl9 levels may be a useful biomarker to estimate inflammation and IVIG responsiveness to KD.

Occupational accidental injury deaths in Tokyo and Chiba prefectures, Japan: A 10-year study (2011-2020) of forensic institute evaluations

Occupational accidental injury deaths (OAIDs) are a major social problem, and the analysis of individual cases is important for developing injury prevention measures. In this study, OAIDs with autopsies performed at forensic facilities in the metropolitan area of Japan (Tokyo and Chiba prefectures) from 2011 to 2020 were reviewed. The epidemiological characteristics of these OAIDs (n = 136), which accounted for 13.5% of OAIDs reported in the region during the study period, were compared with those of non-occupational accidental injury deaths (non-OAID) cases (n = 3926). Among OAID cases, 134 (98.5%) were men and 13 (9.6%) were foreign-born workers, which was significantly more than in non-OAID cases (p < 0.001, respectively). OAIDs were most frequent in construction (39.0%) followed by the manufacturing category (21.3%). The percentage of OAIDs in workers aged 65 and over showed an increasing trend. Most accidents occurred just after the start of work or just before the workday ended, as well as during the peak months of the year. The most common type of accident was fall/crash from a height (25.0%), and the most common injury site was the chest; none of these cases were confirmed to have been wearing a safety belt properly. Among foreign-born workers, the most common type of accident was caught in/between. As the working population is expected to change in the future, and an increase in the number of older adults and foreign workers is expected, it is necessary to take preventive measures such as improving the work environment based on ergonomics and providing safety education.

Cadmium body burden and health effects after restoration of cadmium-polluted soils in cadmium-polluted areas in the Jinzu River basin

BACKGROUND

Itai-itai disease is caused by environmental cadmium (Cd) pollution in the Jinzu River basin in Japan. To reduce the Cd contamination of rice, soil restoration of paddy fields was carried out. We evaluated the effect of soil restoration on the health status of residents of the former Cd-polluted area.

METHODS

Participants were 1,030 men and 944 women who lived in the area of restoration of Cd-polluted rice paddies. First morning urine was collected and urinary Cd, β2-microglobulin (β2MG), and N-acetyl-β-D-glucosaminidase (NAG) levels were measured. Associations among age, years of residence before and after soil restoration, and urinary Cd, β2MG, and NAG levels were evaluated by multiple regression analysis.

RESULTS

The geometric mean (interquartile range) of urinary Cd (µg/g Cr) was 1.00 (0.58-1.68) in men and 1.67 (1.02-2.91) in women. The geometric means of urinary β2MG (µg/g Cr) and NAG (U/g Cr) were 174.6 (92.6-234.2) and 1.47 (0.72-3.14) in men, and 217.6 (115.3-28.7) and 1.48 (0.73-2.96) in women, respectively. Urinary Cd, β2MG, and NAG were significantly positively correlated (p < 0.01 all). Age and duration of residence in the Cd-polluted area before soil restoration were independently associated with urinary Cd, β2MG, and NAG. Among the 916 participants who had resided in the area before the soil restoration, urinary Cd concentrations were significantly higher, thus by 1.03-fold (95% CI, 1.01-1.04) in men and 1.03-fold (95% CI, 1.01-1.05) in women, when the years of residence before soil restoration by each 5-years increment. By contrast, urinary Cd concentrations were significantly lower, thus 0.97-fold (95% CI, 0.96-0.99) lower in men and 0.97-fold (95% CI, 0.95-0.99) lower in women, by each 5-year increment of residence after soil restoration. A similar association was observed for urinary β2MG concentration, and no significant association was observed for urinary NAG levels in men or women.

CONCLUSIONS

Cd exposure and associated renal tubular dysfunction in residents of a former Cd-polluted area were influenced by Cd exposure from the environment prior to soil restoration. Soil restoration in Cd-polluted areas reduced the Cd exposure of local residents.

Detection of lisdexamfetamine and its metabolite d-amphetamine in urine and gastric contents collected from a cadaver at forensic autopsy

PURPOSE

Lisdexamfetamine (LDX), which is used for the treatment of attention-deficit/hyperactivity disorder and narcolepsy, is composed of L-lysine attached to dextroamphetamine (d-amphetamine). In this article, we report a forensic autopsy case in which prescription drugs were unknown at autopsy. While amphetamine was detected, methamphetamine could not be detected by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in any of samples collected. Thus, we aimed to quantify LDX concentrations in autopsy samples and to prove that the amphetamine detected in this case was due to metabolized LDX.

METHODS

Femoral vein blood, cardiac whole blood, urine, and gastric content samples were taken at autopsy for toxicological analysis. Qualitative and quantitative analyses were performed using LC-MS/MS. In addition, optical isomer separation for the amphetamine detected was conducted. The stability of LDX in whole blood and urine was also examined at three different temperatures.

RESULTS

The concentrations of LDX were < 4.00, 30.9, and 4.42 ng/mL in whole blood, urine, and gastric content samples, respectively. The concentrations of amphetamine were 329, 510, 2970, and 915 ng/mL in femoral vein blood, heart whole blood, urine, and gastric contents, respectively. The amphetamine detected in this case was identified to be only d-amphetamine by optical isomer separation. The d-amphetamine detected was considered to be derived from LDX. Stability experiments revealed that LDX in whole blood decreased at ambient temperature.

CONCLUSIONS

The results in the present case report may be useful in interpreting whether or not the amphetamine detected in a cadaver is a metabolite of LDX.

Carrion flies (Insecta: Diptera) found on human cadavers in Chiba prefecture, Honshu, Japan, with the first record of Fannia prisca from a human corpse

Forensic entomology (FE) involves the collection and analysis of necrophagous insects and arthropods for postmortem interval estimation based on their growth and succession. In Japan, research on FE is limited, and the predominant species of necrophagous insects and their distribution have not been clarified. The present study aimed to clarify the actual situation of insects, targeting Diptera collected from human cadavers, in Chiba Prefecture. We targeted the cases for which specimens could be collected from forensic autopsies conducted at the Legal Medicine Department of Chiba University Graduate School of Medicine or from human bodies handled by the Chiba Police in 2019. We specifically chose cases from which adult insects could be bred. Fifty cases were applicable, and 47 cases were successful in rearing adult flies. Sixteen species of Diptera were identified: six species of Calliphoridae, four species of Sarcophagidae, and a few species of Fanniidae, Muscidae, Phoridae, Piophilidae, and Stratiomyidae. The most frequently observed species were Lucilia sericata (20 cases) and Chrysomya pinguis (18 cases). For the first time, globally, we recorded the presence of Fannia prisca in a human cadaver. In conclusion, this is the first report to reveal the presence of carrion flies in human death cases in Chiba Prefecture, Japan. Research in FE is important in the context of the Japanese natural and social environment since this can aid forensic investigations conducted by authorities.

Prevalence of blood-borne infections in forensic samples: Epidemiology in areas of Chiba, Japan

OBJECTIVES

To statistically clarify the prevalence and risk factors of infections in forensic autopsy cases in Chiba Prefecture, Japan. The aim was to improve preventive measures against infection in forensic autopsies.

METHODS

We retrospectively investigated the positive detection rates of five infections (hepatitis B, HBV; hepatitis C, HCV; human immunodeficiency virus, HIV; human T-lymphotropic virus, HTLV; Treponema pallidum, TP) using 1491 samples obtained in forensic autopsy at our facility from 2014 to 2018. In addition, risk factors related to infection such as methamphetamine and tattoos were analyzed. Pearson's chi-square test was used for statistical analysis, and the difference was judged to be significant at p < 0.05.

RESULTS

Among our samples, 9.0% of cadavers tested positive for infection, and the prevalence rates for HBV, HCV, HIV, HTLV, and TP were 1.0%, 6.7%, 0.3%, 0.7%, and 1.1% respectively. Statistically, cadavers linked to information about methamphetamine use had a 7.2 times higher rate of infection, and those with tattoos had a 5.6 times higher rate of infection, with HCV being the predominant cause.

CONCLUSIONS

To limit the risk of infection among autopsy workers, cadavers and samples should be handled on the presupposition that the bodies are at risk of infections. It is also important to obtain as much information as possible about the medical history and potential illegal drug use to help assess the risk of infection in a patient during forensic autopsy. We propose that all autopsy cases should be screened for infections whenever possible.

A case of fatal fulminant fat embolism syndrome following multiple fractures resulting from a fall

Fat embolism syndrome is a life-threatening condition in which fatty substances enter the circulation and cause respiratory distress and neurological symptoms. It can occur following trauma and severe fat embolism occurring soon after trauma is known as fulminant fat embolism syndrome. Although fat staining of the lungs is helpful for diagnosing fat embolism syndrome at autopsy, clinical and other information is needed to determine the relationship between cause of death and the syndrome. In this report, we describe the macroscopic, microscopic, and computed tomography (CT) findings specific for fat embolism that were observed in a patient with fulminant fat embolism syndrome who died soon after the injury. An 85-year-old woman fell from a bath stretcher during assisted bathing and died 3 h later. Autopsy revealed fractures of the left femoral neck and other bones, as well as large amounts of fat-like material in the right and left pulmonary arteries. Histological examination of the lung with Oil red O staining showed extensive fat vacuoles. Based on these findings and postmortem CT images of the fractures and fatty globules in the pulmonary arteries detected prior to death, the cause of death was determined to be blunt force trauma, with fat embolism syndrome playing a significant role. This case is an example of fulminant fat embolism, which can be fatal in a short period of time, and demonstrates that CT performed postmortem but before autopsy can be useful in detecting fat embolism syndrome due to trauma.

Trends and Characteristics in Health Care-related Deaths Investigated through Medico-legal Autopsies after System Changes in Japan

In Japan, a new cause-of-death investigation system and related new laws were enacted in the mid-2010s. These laws provided for an autopsy system for non-criminal unnatural deaths and a medical accident investigation system outside the criminal justice process for health care-related deaths. We retrospectively explored changes in the number and characteristics of medico-legal autopsy cases of health care-related deaths in Chiba Prefecture, Japan, and examined trends over time during these reforms. We found that the percentage of forensic autopsies based on the Code of Criminal Procedure for health care-related deaths had decreased significantly. The number of autopsies of accidental and unintentional deaths in nursing homes, which are not covered by the newly established medical accident investigation system, has been increasing, reflecting the ageing of society. The trend toward decriminalisation of health care-related deaths was expected to contribute more to medical safety if the scope was expanded and a system for disclosure of autopsy information was established.

Evaluation of Post-Mortem Interaction between Hemoglobin and Oxime-Type Carbamate Pesticides

Oxime-type carbamate pesticides having an oxime moiety such as aldicarb, butocarboxim, methomyl, oxamyl, and thiofanox are widely used and have been detected in many fatal cases of accidental exposure or suicide. In forensic toxicology, the accurate determination of blood pesticide concentration is obligatory to prove death by oxime-type carbamate pesticide poisoning. However, the fatal pesticide concentration in blood at autopsy differs from that at the time of death. In this study, we found that oxime-type carbamate pesticides were decomposed by Hb in a temperature-dependent fashion. The mechanism underlying methomyl, aldicarb, oxamyl, and thiofanox decomposition involves the formation of adducts with the amino acids in Hb. With regard to butocarboxim, its decomposition involves the oxidation of the free form and the formation of adducts with the amino acids in Hb. The mass spectra obtained by liquid chromatography quadrupole time-of-flight mass spectrometry revealed that carbamylated amino acid adducts such as W_car-adduct and V_car-adduct were formed in Hb solution incubated with methomyl, aldicarb, oxamyl, and thiofanox, whereas alkylated amino acid adducts such as W_alkyl-adduct were formed in Hb solution incubated with butocarboxim. These results indicate that aldicarb, butocarboxim, methomyl, oxamyl, and thiofanox are post-mortem changed by Hb.

Dental characteristics associated with methamphetamine use: analysis using forensic autopsy data

Background

Little is known regarding the oral conditions in nonelderly methamphetamine users, such as the presence of dental caries and periodontitis. We aimed the oral conditions between methamphetamine users and non-users stratified by age groups.

Methods

In this cross-sectional study, computed tomography images were obtained from 3,338 decedents at two forensic medicine departments in Japan. Decedents aged > 20 or ≤ 64 years were included in the study and categorised into methamphetamine-detected (MA) and undetected (control) groups based on toxicological examinations. Decedents in the MA and control groups were matched for age and sex in a 1:4 ratio. The matched pairs were further categorised into young adults (20–44 years) and middle-aged adults (45–64 years). Oral characteristics, including the decayed, missing, and filled teeth (DMFT) index; periodontitis; distributional patterns of each tooth condition; and occlusal status, were compared between the MA and control groups for each age category. Among 3,338 decedents, 37 young and 55 middle-aged adults in the MA group were matched with 148 and 220 adults in the control group, respectively.

Results

In the young adult group, methamphetamine use was significantly associated with higher DMFT index (mean [standard deviation], 14.2 [7.6] vs 11.0 [6.1]; p = 0.007), smaller number of filled teeth (2.8 [2.9] vs 5.3 [4.0]; p = 0.001), higher proportion of periodontitis (39.0% vs 6.8%; p < 0.001), and lower proportion of occlusal support (54.1% vs 81.1%; p = 0.001). Young adult methamphetamine users tended to have untreated decayed canines and molars and missing molars. These findings were similar to those in middle-aged adults except the tendency to have missing maxillary incisors.

Conclusions

Nonelderly methamphetamine users had distinctive oral characteristics that may help screen for methamphetamine abuse through dental examinations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02182-6.

Lipiodol remnants misinterpreted as a metal device on postoperative abdominal X-ray images

We experienced a case of pregnancy after hysterosalpingogram and residual lipiodol in the extraperitoneal space. Initially, we suspected a metallic remnant; however, analysis by mass spectrometer confirmed that it was a remnant of lipiodol.

Sixty-eight cases of postmortem pink teeth observed in dental autopsies of unidentified cadavers

The pink teeth phenomenon was first reported in people who died by hanging or drowning in 1829. In recent years, there have been many reports that the occurrence of postmortem pink teeth is closely related to the condition of surroundings and time after death rather than to the cause of death, as had previously been thought. We observed pink teeth in 68 of 324 unidentified cadavers autopsied during 2015-2021, and we investigated the relationship of pink teeth with age, sex, cadaveric condition, time after death, tooth type, and cause of death. The results showed no significant differences in the occurrence of pink teeth according to sex or place of discovery (indoors, outdoors, or in water). Pink teeth tended to be observed below the age of 60 years. In the 68 cases with pink teeth, 29.1% of all vital teeth were affected, with the anterior teeth being most common. No evidence was found that supported an association between pink teeth and cause of death. These results are largely consistent with recent reports on postmortem pink teeth. As it stands, the pink teeth phenomenon may be nonspecific and must not be misinterpreted in medico-legal investigations. This case series provides further evidence supporting recent reports and contributes to clarifying in greater detail the mechanisms of the coloration and fading of pink teeth.

Simple and simultaneous quantification of cyanide, ethanol, and 1-propanol in blood by headspace GC–MS/NPD with Deans switch dual detector system

Cyanide is a powerful and rapidly acting poison. In Japan, cyanide poisoning is rare, and regular cyanide testing can be costly and time consuming. In contrast, alcohol analysis is routinely performed in most forensic laboratories. In this study, we attempted to develop a method for the simultaneous quantification of cyanide and alcohols in blood using headspace gas chromatography (HS-GC). As nitrogen-phosphorus detection (NPD) is more sensitive to hydrogen cyanide than mass spectrometry (MS), a Deans switch was used to switch the detectors during a single run. The separation provided by three analytical columns, PoraBOND Q, CP-Sil 5 CB, and HP-INNOWax, was investigated, and PoraBOND Q was selected. The use of HS-GC-MS/NPD with a Deans switch enabled the simple and simultaneous quantification of cyanide, ethanol, and 1-propanol. Eighteen other volatile compounds were detected in the SIM/scan mode of the MS.

A quantitative comparison between using sodium hypochlorite as a digestion method for the diatom test and the conventional method using fuming nitric acid

OBJECTIVE

To determine the efficacy of using sodium hypochlorite (NaClO, Purelox) as a simple and rapid alternative digestion method for the diatom test through a quantitative comparison with the conventional method that uses fuming nitric acid (HNO₃).

MATERIALS AND METHODS

In experiment 1, using 30 water samples, the NaClO and HNO₃ methods were compared using paired t-test. In experiments 2 and 3, we included blank human lung plus 13 water samples and total of 32 drowned human lung samples, respectively, to compare the NaClO and HNO₃ methods using paired t-test. The relationship between the concentration ratio and background factors was tested in experiment 3. Welch's t-test was used to determine differences in the ratio between the lung side and sex, whereas Pearson's correlation coefficient was used to determine the correlation between the ratio and either age or postmortem interval. The geometric mean of two counts was used for each specimen and all counts were logarithmically transformed to base 2 in the statistical analysis.

RESULTS

The NaClO method was completed within 80 min for any sample. In experiment 1, there was no significant difference between the NaClO and HNO₃ methods using water samples (the mean of the ratios: 0.99, 95% confidence interval (95%CI: 0.89-1.10, P = 0.80). In experiment 2, the count of the NaClO method was lower than that of the HNO₃ method using lung plus water samples (the mean of the ratios: 0.47, 95% CI: 0.35-0.65, P = 0.0002). In experiment 3, the concentration of the NaClO method was lower than that of the HNO₃ method using drowned lung samples (the mean of the ratios: 0.28, 95% CI: 0.20-0.38, P < 0.0001). A weak correlation between the postmortem interval and the ratio of the two methods was observed (r = -0.58, P = 0.012), although no difference between lung sides or sexes were detected (P = 0.87 and P = 0.50, respectively) and no correlation occurred between age and the ratio (r = 0.15, P = 0.43).

CONCLUSION

Using NaClO as a simple and rapid digestion method for diatom testing of water samples would be an excellent alternative to conventional methods. Although the method's diatom detection rate for the lung samples was not optimal, it was still shown to be a feasible method.

Age estimation by evaluation of osteophytes in thoracic and lumbar vertebrae using postmortem CT images in a modern Japanese population

Estimation of age at death is important in forensic investigations of unknown remains. There have been several reports on applying the degree of osteophyte formation-an age-related change in the vertebral body-for age estimation; however, this method is not yet established. This study investigated a method for age estimation of modern Japanese individuals using osteophytes measured on CT images. The sample included 250 cadavers (125 males) aged 20-95 years. The degree of osteophyte formation was evaluated as score O (0-5 points), and the degree of fusion of the osteophytes between the upper and lower vertebrae was evaluated as score B (0-2 points). Age estimation equations were developed using regression analyses with seven variables, determined by scores O and B, and the equation with the smallest standard error of estimate (SEE) was obtained when the number of vertebrae with score O ≥ 2 was used as the explanatory variable. Age estimation with SEE of about 10 years was possible even when partial vertebrae with a high degree of osteophyte formation were used, showing its potential for practical application. The cutoff value for age estimation was established using the receiver operating characteristic curve analysis, wherein good results were obtained for all variables (area under the curve ≥ 0.8). The combination of the estimation equation and the cutoff value can narrow the range of age estimates.

Technical and interpretive pitfalls of postmortem CT: Five examples of errors revealed by autopsy

Image acquisition of dead bodies, particularly using postmortem computed tomography (PMCT), has become common in forensic investigations worldwide. Meanwhile, in countries such as Japan which have an extremely low rate of autopsy, PMCT is being increasingly used in the clinical field to certify the cause of death (COD) without performing an autopsy or toxicological tests, even in cases of unnatural death. Additionally, these PMCT images are predominantly interpreted by clinical personnel such as emergency physicians or clinicians who are not trained in PMCT interpretation and who work for the police, that is, the so-called police doctors. Many potential pitfalls associated with the use of PMCT have been previously described in textbooks and published papers, including the pitfalls of not performing a complete forensic pathology investigation, and the use of physicians without appropriate PMCT training to interpret PMCT and direct death investigation and certification. We describe five examples in which apparent misdiagnosis of COD based on PMCT misinterpretation was revealed by autopsy. Here are the five examples of errors: (1) Postmortem changes were misinterpreted as COD, (2) resuscitation effects were misinterpreted as COD, (3) COD was determined after an incomplete examination, (4) fatal findings caused by external origin were wrongly interpreted as 'of internal origin' based on PMCT, and (5) non-fatal findings on PMCT were wrongly interpreted as fatal. Interpretation of PMCT by appropriately trained physicians and an accompanying complete forensic investigation, including autopsy when indicated, is necessary to prevent significant errors in COD determination and related potential adverse medicolegal consequences.

Experimental water injection into lungs using an animal model: Verification of the diatom concentration test to diagnose drowning

BACKGROUND

In forensic medicine, the diatom test is used to diagnose drowning. Drowning and postmortem immersion can be distinguished by calculating the ratio of diatom concentration in the lungs and drowning water (L/W ratio). However, this claim was based on the unproven hypothesis that diatoms may be concentrated in the lungs due to respiratory movements. This study was conducted to examine whether the L/W ratio increased with experimental water injection.

METHODS

A total of two experiments was performed using 22 non-drowned cat carcasses found on dry land. First, for the experimental postmortem immersion, we soaked seven whole-body cat carcasses in pond water for an hour. Second, the pond water was experimentally injected one or ten times into each harvested lung from seven and eight cats, respectively. In the diatom test, two diatom species (Aulacoseira ambigua and Discostella asterocostata) that were dominantly observed in pond water as well as other diatom species were counted separately. The L/W ratios of each cat were calculated. Univariate linear regression analysis was performed to demonstrate the association among L/W ratios and the three categories of the experiments. The L/W ratios of the two experiments were compared with those of drowning or postmortem immersion cases of humans or cats.

RESULTS

It was revealed that the clear L/W ratio differences between the three groups (experimental postmortem immersion<0.02, 1-injection < 0.2, 10-injection > 0.9 for all diatom counting) were with statistically significant as proven by the univariate regression analyses. In actual cases of cats and humans, L/W ratios were>0.4 for drowning and<0.04 for postmortem immersion.

CONCLUSION

The L/W ratio increased with multiple experimental water injections into the lungs, thereby verifying the validity of the diatom concentration test to diagnose drowning. The diatom test can be used to distinguish between drowning and postmortem immersion in humans and cats by calculating the L/W ratio.

Factors associated with methamphetamine use in Japanese people who died of unnatural causes: Analysis using forensic autopsy reports

This study aimed to examine factors related to methamphetamine use in Japanese people who died of unnatural causes. This study used a cross-sectional design. A total of 3343 forensic autopsy reports were obtained from two forensic medicine departments in the Kanto region of Japan. We classified the decedents who underwent forensic autopsies into methamphetamine/amphetamine (MA) and undetected (comparison) groups based on toxicological examination. We matched the decedents in the MA group with those in the comparison group at a 1:4 ratio based on sex and age. The variables, including gang members, criminal records, tattoos, body mass index, infections, concurrent psychotropic drug use, and cause of death, were compared between the groups. Of the 3343 decedents, we matched 109 in the MA group with 436 in the comparison group. Methamphetamine use was significantly associated with gang membership (13.8% vs. 3%, p < 0.001), criminal records unrelated to methamphetamine (47.7% vs. 13.8%, p < 0.001), tattoos (29.2% vs. 6.4%, p < 0.001), and hepatitis C virus infection (48.0% vs. 3.6%, p < 0.001). One-third of the patients in the MA group died from poisoning. This is the first study to show the physical and social characteristics associated with methamphetamine use in Japanese people who died of unnatural causes. Our results could be extended to people with methamphetamine use disorder at risk of death and enable the development of policies and practices to provide necessary intervention in a timely manner.