記述言語：日本語   出版者・発行元：Forensic Science Medicine and Pathology  

Purpose: The lack of specific autopsy findings for carbon dioxide (CO<inf>2</inf>) intoxication hinders the determination of cause of death based on autopsy findings alone. In addition, when death occurs in a space is filled with CO<inf>2</inf> or other gases, the cause of death must be distinguished between intoxication and asphyxia due to oxygen deficiency, which also has no specific autopsy findings. In this study, we aimed to identify diagnostic markers of mRNA expression in the brainstem that indicate cause of death in cases of suspected CO<inf>2</inf> intoxication. Methods: Mouse models of CO<inf>2</inf> intoxication (composition of ambient gases at 70% CO<inf>2</inf>, 20% O<inf>2</inf>, and 10% N<inf>2</inf>) and asphyxia due to oxygen deficiency (5% O<inf>2</inf>, 95% N<inf>2</inf>) were used to identify mRNA markers specific to intoxication or asphyxia. Results: Using RNA-Sequence analysis, we identified 7 candidate genes for qRT-PCR analysis: Acid-sensing ion channel 4 (Asic4), Early growth response protein 1 (Egr1), Neurogranin (Nrgn), Opioid receptor delta 1 (Oprd1), Semaphorin 3f (Sema3f), Transthyretin (Ttr), and Tryptophan hydroxylase 2 (Tph2). We observed a significant increase of Nrgn mRNA expression in the brainstem of CO<inf>2</inf> intoxication and a significant increase of Ttr mRNA expression in the brainstem of asphyxia due to oxygen deficiency. Conclusion: Assays for the expression of Nrgn and Ttr in the human brainstem may assist in the diagnosis/differential diagnosis of CO<inf>2</inf> intoxication and asphyxia due to oxygen deficiency, respectively.

DOI： 10.1007/s12024-025-00981-1

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PubMed

記述言語：日本語   出版者・発行元：Forensic Science Medicine and Pathology  

A mixture of baking soda (sodium hydrogen carbonate) and citric acid is used for cleaning purposes, but, in recent years, this mixture has been introduced on the internet as a method for suicide. Here, we report a case in which the two agents were mixed in a bathtub to generate carbon dioxide (CO<inf>2</inf>). A man in his early 60s was found dead in his clothes in a bathtub with a lid. Postmortem changes were somewhat progressed, but only pulmonary edema was observed, with no injuries or lesions that could have led to cause of death, and no drug toxicants detected. Empty containers of baking soda (789 g) and citric acid (850 g) were found at the scene. We conducted a reproduction experiment showing that CO<inf>2</inf> reached a lethal concentration (~ 60%) within 12 s, but the O<inf>2</inf> concentration was about 10%, which is not a lethal concentration. Therefore, it is highly likely that the man died of CO<inf>2</inf> intoxication within a short period of time and before he would have suffered asphyxiation due to oxygen deficiency. Normally, this result can only be obtained with the cooperation of an investigative agency and a large-scale reproduction experiment, but we were able to diagnose the cause of his death, including a differential diagnosis of asphyxia due to oxygen deficiency, by means of a reproduction model at 1/35 scale that could easily be performed in the laboratory.

DOI： 10.1007/s12024-024-00927-z

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PubMed

記述言語：日本語   出版者・発行元：(一社)日本医用画像工学会  

死後画像診断は解剖前に体内の異変を把握できるため,より正確かつ短時間で解剖を行うために有用である.一方で,画像撮影から解剖までの短時間で読影が求められる,死後画像に精通した読影医が少ないといったことから画像解析による支援が期待されている.著者らは,頭部死後CT画像の脳内出血の種類,位置,出血量を把握するために機械学習による脳内出血セグメンテーションモデルの開発を行っている.本研究では密なスキップ接続と残差接続を持つDense Residual U-Netを提案し,残差接続を持つResidual U-Net,スキップ接続を持つDense U-Netと比較する.実験結果ではスキップ接続が最も密な提案法で最もDice係数が高くなり,脳内出血セグメンテーションの性能向上に有効であることを確認した.(著者抄録)

記述言語：日本語   出版者・発行元：Scientific Reports  

Sudden death in the bathroom (bath-related death) occurs more frequently in Japan than in other countries. To clarify the epidemiological characteristics of bath-related deaths, we reviewed inquest records of deaths in Kagoshima Prefecture from 2006 to 2019. We identified 2689 cases of bath-related death. Of these cases, 90% were among people aged ≥ 65 years. The majority occurred in a home bathtub between 16:00 and 20:00. Most deaths (52.0%) occurred in winter (December–February), and there were extremely strong negative correlations with the environmental temperatures (maximum, minimum, and mean) on the day of death. We identified the environmental temperature during cold winter months that bath-related deaths are likely to occur in Kagoshima, although further investigation concerning the effects of other confounding factors is required. Forensic autopsies have only been performed in 29 cases and the cause of death was not diagnosed correctly in the majority of cases. Although autopsies are essential to elucidate the pathogenesis of the deaths, it is difficult to increase the rate of autopsies under the current Japanese death investigation system. Therefore, we suggest that the best way to prevent bath-related death is establishing an “Alert system” based on our results, and to have people refrain from bathing on dangerous days.

DOI： 10.1038/s41598-023-29400-7

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PubMed

記述言語：日本語   出版者・発行元：Forensic Science International Reports  

The 7-month-old girl was left in a nursery until following morning. About 3 h after being given milk, she was found dead in a right lateral supine position. There was no external evidence of injury to suggest a maltreatment. Hemorrhages were present in the accessory respiratory muscles, but the most notable findings were masses on either side of the trachea and immediately inferior to the thyroid gland. Both of masses were in continuity with the intrathoracic thymus. Histopathologically, the masses showed normal thymic structure and collagen fibers on the left side of the trachea showed metachromasia on Masson's staining. There were no remarkable findings in organs except for congestion. The cause of death was determined to be mechanical asphyxia due to tracheal compression by the cervical ectopic thymus. Hemorrhage in the accessory respiratory muscle was considered to be caused by effortful breathing during the process of asphyxia. The metachromasia of Masson's stain on the trachea may be due to the same mechanism as a “compression mark reaction”, and may be useful in proving compression by the ectopic thymus. We consider that chronic compression of the trachea led to the tracheomalacia, which enabled the final lethal compression when lying in a right lateral supine position. An ectopic thymus is caused by a failure of descent of the embryonic thymic tissue into the thoracic cavity at the appropriate developmental stage and is generally asymptomatic. However, the cervical ectopic thymus should be considered in the diagnosis of a cause of sudden infant death.

DOI： 10.1016/j.fsir.2022.100286

Scopus

記述言語：日本語  

記述言語：日本語