Mutations in CHCHD2 are linked to a familial, autosomal dominant form of Parkinson’s disease (PD). The gene product may regulate mitochondrial respiratory function. However, whether mitochondrial dysfunction induced by CHCHD2 mutations further yields α-synuclein pathology is unclear. Here, we provide compelling genetic evidence that mitochondrial dysfunction induced by PD-linked CHCHD2 T61I mutation promotes α-synuclein aggregation using brain autopsy, induced pluripotent stem cells (iPSCs) and Drosophila genetics. An autopsy of an individual with CHCHD2 T61I revealed widespread Lewy pathology with both amyloid plaques and neurofibrillary tangles that appeared in the brain stem, limbic regions and neocortex. A prominent accumulation of sarkosyl-insoluble α-synuclein aggregates, the extent of which was comparable to that of a case with α-synuclein (SNCA) duplication, was observed in CHCHD2 T61I brain tissue. The prion-like activity and morphology of α-synuclein fibrils from the CHCHD2 T61I brain tissue were similar to those of fibrils from SNCA duplication and sporadic PD brain tissues. α-Synuclein insolubilization was reproduced in dopaminergic neuron cultures from CHCHD2 T61I iPSCs and Drosophila lacking the CHCHD2 ortholog or expressing the human CHCHD2 T61I. Moreover, the combination of ectopic α-synuclein expression and CHCHD2 null or T61I enhanced the toxicity in Drosophila dopaminergic neurons, altering the proteolysis pathways. Furthermore, CHCHD2 T61I lost its mitochondrial localization by α-synuclein in Drosophila. The mislocalization of CHCHD2 T61I was also observed in the patient brain. Our study suggests that CHCHD2 is a significant mitochondrial factor that determines α-synuclein stability in the etiology of PD.
Sudden death in a hot bathtub occurs frequently in Japan, particularly among elderly people. This retrospective report describes the epidemiologic circumstances and physical findings at autopsy. In total, 268 victims were found unconscious or dead during tub bathing. After postmortem examination, the manner of death was judged as natural cause in 191 (71.2%) and accidental drowning in 63 (23.5%) cases. Mean age (SD) was 72.1 (15.2) years with no significant difference between males and females. A seasonal difference was evident: the winter displayed the highest frequency. Drowning water inhalation, which was confirmed in 72% of victims, was absent in the others. The most common observations on postmortem examination were cardiac ischemic changes and cardiomegaly. Water inhalation signs were evident in a significantly fewer victims exhibiting these factors. In contrast, inhalational findings were observed more frequently in victims with other backgrounds such as alcohol intake, mobility disturbance, and history of epilepsy. Annual mortality in Japan from accidental drowning in persons aged older than 75 years is 33 deaths per 100,000 population. However, this number may be considerably underestimated as pathologists tend to regard lack of water inhalation as indicating a natural cause of death. Confusion in diagnosis remains consequent to the accidental and natural aspects of "dead in hot bathtub" phenomenon.
Many breakwaters were damaged by the Great East Japan Earthquake of March 11, 2011. The majority of the breakwaters were destroyed or deformed under tsunami overflow; however, the failure mechanism under tsunami overflow is not clear. Therefore, with the main objective of this report being to clarify the stability of breakwaters under tsunami overflow, hydraulic model experiments and numerical simulations were conducted with Kamaishi Bay breakwaters as the subject, and failure mechanisms of the trunk of the breakwaters were examined.
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