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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.

To study the quantitative effect of ethanol on the diatom test for water and lung samples.In experiment 1, we tested 20 water samples taken from natural water areas. In experiments 1-1 and 1-2, each sample was digested with sodium hypochlorite (NaClO) solution (Purelox) and fuming nitric acid (HNOIn experiments 1-1, 1-2, 1-3, 1-4, and 2, the geometric means of the ratios derived from the two methods (with/without ethanol) were 0.70 (95 % confidence interval [CI]: 0.65-0.77, P 0.001), 0.83 (95 % CI: 0.73-0.93, P = 0.005), 3.00 (95 % CI: 2.31-3.91, P 0.001), 0.91 (95 % CI: 0.79-1.04, P = 0.164), and 3.06 (95 % CI: 2.28-4.41, P 0.001), respectively.Our experiments suggest that ethanol would be useless in diatom tests of water samples or in the conventional (HNO

Understanding the actual conditions of methamphetamine (MA)-related death is important from the perspectives of criminal justice and public health. In this report, we review 104 cases of MA-related death handled by our departments between January 2014 and December 2020. Based on information from police and autopsy examinations, we classified the cases into the following categories: "accidental intoxication" ("MA only" and "multiple drugs or alcohol"), "fatal disease" ("definitively MA-related," "possibly MA-related," and "unlikely MA-related"), "accident," "suicide," "homicide," and "undetermined." The total number and annual trends for each category and their respective femoral blood concentrations were investigated. "Fatal disease" was the most common category (48 cases), followed by "suicide" (25 cases), "accidental intoxication" (14 cases), and "accident" (11 cases). "Definitively MA-related" in which MA may have played a role in their onset or exacerbation accounted for the majority of "fatal disease": 12 cases of heart disease, 4 cases of aortic dissection, 12 cases of cerebral hemorrhage, and 4 cases of subarachnoid hemorrhage. Cases classified as "definitively MA-related" died with lower femoral blood concentrations of MA compared with "MA only." Cases with "fatal disease" might have been misdiagnosed as "death by natural causes" if a proper autopsy and toxicology examinations were not performed. In death investigations, it is necessary to keep in mind that there are some MA-related deaths, and efforts should be made to increase awareness about the risk of death in using this drug.

A man and a woman were found dead in the same car with a burned coal briquette. The cause of death of the woman was assigned to acute carbon monoxide (CO) poisoning without difficulty based on typical findings associated with this condition, including elevation of carboxyhaemoglobin (COHb). However, the man had an unremarkable elevation of COHb and a higher rectal temperature compared to that of the woman. Postmortem computed tomography (PMCT) revealed ambiguous low-density areas in the bilateral globi pallidi. Further analysis by postmortem magnetic resonance (PMMR) imaging showed these lesions more clearly; the lesions appeared as marked high signal intensity areas on both the T2-weighted images and the fluid-attenuated inversion recovery sequences. A subsequent autopsy revealed signs of pneumonia, dehydration, starvation, and hypothermia, suggesting that the man died from prolonged CO poisoning. Both globi pallidi contained grossly ambiguous lesions, and a detailed neuropathologic investigation revealed these lesions to be coagulative necrotic areas; this finding was compatible with a diagnosis of prolonged CO poisoning. This case report shows that postmortem imaging, especially PMMR, is useful for detecting necrotic lesions associated with prolonged CO poisoning. This report further exemplifies the utility of PMMR for detecting brain lesions, which may be difficult to detect by macroscopic analysis.

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.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.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.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 man in his seventies who lived alone was found dead in his home. Postmortem computed tomography (CT) performed prior to autopsy showed right-sided tension pneumothorax. Autopsy revealed an active pulmonary tuberculosis (TB) lesion. Macroscopic and histopathological findings showed pleural infiltration by TB lesions, suggesting that tension pneumothorax developed in association with TB infection. Routine postmortem CT performed prior to autopsy is useful in screening for TB because the presence of TB lesions can be confirmed from characteristic pulmonary findings. However, it may be difficult to identify tuberculous pulmonary lesions on CT if pneumothorax occurs and the lung collapses completely as in this case. Thus, forensic pathologists and radiologists should be cognizant of this rare complication of TB.

The diatom test method using sodium hypochlorite (NaClO) was equivalent to the conventional method in water samples. However, the method using NaClO was inferior to the conventional method in lung samples, in which ethanol was used and the reaction with NaClO was longer compared with the method in water samples. Using water samples, we aimed to clarify whether these differences affect the diatom test result.Thirteen water samples from natural water sources were each divided into four parts corresponding to four (2 × 2) digestion methods: 3 "digestion" vs. 1 "digestion" and with ethanol vs. without ethanol. After the base-2 logarithmic transformation, the diatom counts were analyzed using three-way analysis of variance (ANOVA); factor 1 was "digestion times," factor 2 was "ethanol," and factor 3 was "sample number," and the interaction between factors 1 and 2 was also analyzed.The geometric means of the diatoms from the 3 "digestion" with ethanol method, the 3 "digestion" without ethanol method, the 1 "digestion" with ethanol method, and the 1 "digestion" without ethanol method were 373.5, 551.8, 436.6, and 522.0, respectively. ANOVA showed a significant difference in factor 2 (P = 1.7 × 10Ethanol may decrease the diatom count in the diatom test using NaClO. In contrast, the diatom frustules do not dissolve through three-times digestion using NaClO.

Stature estimation is one of the most basic and important methods of personal identification. The long bones of the limbs provide the most accurate stature estimation, with the femur being one of the most useful. In all the previously reported methods of stature estimation using computed tomography (CT) images of the femur, laborious manual measurement was necessary. A semi-automatic bone measuring method can simplify this process, so we firstly reported a stature estimation process using semi-automatic bone measurement software equipped with artificial intelligence. Multiple measurements of femurs of adult Japanese cadavers were performed using automatic three-dimensional reconstructed CT images of femurs. After manually setting four points on the femur, an automatic measurement was acquired. The relationships between stature and five femoral measurements, with acceptable intraobserver and interobserver errors, were analyzed with single regression analysis using the standard error of the estimate (SEE) and the coefficient of determination (R2). The maximum length of the femur (MLF) provided the lowest SEE and the highest R2; the SEE and R2 in all cadavers, males and females, respectively, were 3.913 cm (R2 = 0.842), 3.664 cm (R2 = 0.705), and 3.456 cm (R2 = 0.686) for MLF on the right femur, and 3.837 cm (R2 = 0.848), 3.667 cm (R2 = 0.705), and 3.384 cm (R2 = 0.699) for MLF on the left femur. These results were non-inferior to those of previous reports regarding stature estimation using the MLF. Stature estimation with this simple and time-saving method would be useful in forensic medical practice.

Postmortem computed tomography (PMCT) images help identify individuals and extract information from corpses. PMCT may substitute for a standard examination when bodies are severely damaged or when resources are limited in a mass fatality incident. In such situations, the dental information revealed by PMCT has the potential to narrow down candidates for identification further. However, the validity of the dental findings obtained from PMCT images remains unclear. In this study, we investigated the validity of dental findings on PMCT images compared to regular dental examinations as the reference standard. We routinely collected PMCT images of 148 unidentified corpses and compared the dental findings of each tooth obtained from PMCT with those of a regular dental examination. The validity of dental findings of PMCT was measured by sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). We also evaluated the accuracy of dental findings per corpse using 32 teeth as the denominator. The dental findings with high sensitivity and high specificity were a present tooth (0.96 and 0.97), a missing tooth (0.97 and 0.97), pontic (0.92 and 1.00), a dental implant (1.00 and 1.00), and a root filling (0.94 and 0.99). The mean accuracy of the dental findings per corpse in PMCT was 95.6% (standard deviation: 6.9, minimum ≤ median ≤ maximum: 65.6 ≤ 100 ≤ 100). The number of corpses with 100% accuracy in the dental findings was 81 (54.7%). The information obtained in this study highlights the potential use of PMCT during human identification in several settings with limited resources, such as the number of specialists present and the condition of the corpses.

The diagnosis of drowning is an important issue in forensic investigations. Moreover, discriminating between seawater and freshwater drowning is crucial to identify where the drowning occurred. The present study aimed to investigate electrolyte concentrations in pleural fluid in decomposed bodies in late postmortem intervals and derive cut-off values for the diagnosis of seawater and freshwater drowning.Data were collected from 44 seawater drowning cases, 60 freshwater drowning cases, and 30 non-drowning cases with pleural effusion which served as controls. The levels of sodium ion (NaThe receiver operating characteristic analysis revealed that the sensitivity and specificity were both 1.000 for SUMThe electrolyte concentrations in pleural effusion may be useful for the diagnosis of drowning in decomposed bodies with a longer postmortem interval.

We report a fatal case of airway obstruction caused by spontaneous retropharyngeal hematoma (RH) in the setting of treatment with dipyridamole. A 90-year-old woman presented with cervical swelling, neck and chest ecchymoses, and complaints of dyspnea. She suffered cardiopulmonary arrest in the ambulance, and her death was confirmed after transportation to the hospital. The major finding of postmortem computed tomography (PMCT) prior to autopsy was widening of the prevertebral soft tissue. The results of the autopsy indicated that the cause of death was mechanical asphyxia, secondary to pharyngeal and laryngeal compression caused by the RH. There were no evident injuries, medical interventions, or particular diseases, suggesting the spontaneous cause of the RH. To the best of our knowledge, this is the first report of a fatal case secondary to spontaneous RH that was revealed through PMCT imaging.

To elucidate postmortem computed tomography (PMCT) and postmortem magnetic resonance (PMMR) imaging findings suggesting massive fat embolism. Consecutive forensic cases with PMCT and PMMR scans of subjects prior to autopsy were assessed. For PMCT, 16- or 64-row multidetector CT scans were used; for PMMR, a 1.5 T system was used. MRI sequences of the chest area included T2- and T1-weighted fast spin-echo imaging, T2*-weighted imaging, T1-weighted 3-dimensional gradient-echo imaging with or without a fat-suppression pulse, short tau inversion recovery, and in-phase/opposed-phase imaging. At autopsy, forensic pathologists checked for pulmonary fat embolism with fat staining; Falzi’s grading system was used for classification. Of 31 subjects, four were excluded because fat staining for histopathological examination of the lung tissue could not be performed. In three of the remaining 27 subjects, histology revealed massive fat embolism (Falzi grade III) and the cause of death was considered to be associated with fat embolism. CT detected a “fat-fluid level” in the right heart or intraluminal fat in the pulmonary arterial branches in two subjects. MRI detected these findings more clearly in both subjects. In one subject, CT and MRI were both negative. There were no positive findings in the 24 subjects that were fat embolism–negative by histology. In some subjects, a massive fat embolism can be suggested by postmortem imaging with a “fat-fluid level” in the right heart or intraluminal fat in the pulmonary arterial branches. PMMR potentially suggests fat embolism more clearly than PMCT.

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 0.9 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 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.

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