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-Emphysema can be induced in animals by postnatal treatment with dexamethasone (Dex) and such models have been widely used for various research. However, it is not clear what are the effects of Dex on assembly of alveolar elastic fibers in the emphysema model in mice. This study compared the expression profile of genes related to alveolar development between Dex treated and control mice during the treatment from postnatal day 3 (P3) to P14 with a 2-day break. From morphological observation of lung sections on P42, we confirmed the induction of emphysema in the treated mice. The mRNA expression level of fibrillin-1, which consists of microfibrils as a scaffold to form elastic fibers, and fibulin-5, which is a key protein reinforcing the fibers, reached maximum on P7 in control mice. However, in the Dex group, expression levels both types of mRNA were much lower with no clear expression peak. On the other hand, mRNA expression of tropoelastin, the main component in elastic fibers, reached maximum on P5 in the Dex group, which was 9 days earlier than in the control group. At this time, the amount of microfibrils might not be enough for tropoelastin to be deposited completely in Dex treated mice. This imbalance in the expression of tropoelastin and microfibril might interfere with the efficient formation of elastic fibers.

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Background In April 2020, the Japanese government requested that people stay home except when unavoidable for their livelihood, as a COVID-19 emergency measure. Especially, elderly people refrained from going out. We investigated mortality rates from external causes in 2020 among Japanese elderly people. Methods The monthly mortality rates from accidents (V01-X59), traffic accidents (V01-V99) and suicides (X60-X84) among elderly from 2015 to November 2020 were analyzed. Ordinary monthly expected values and reference ranges (RR: 95% range) were calculated by cause and sex and compared with the observed values. Results All accidents: Abnormal increases (beyond the RR) occurred in August for both sexes. Traffic accidents: Extreme decreases (below the RR) occurred in at least 3 months from March to October for each sex. Suicides: Extreme decreases occurred in at least 2 months from February to May for each sex. Abnormal increases occurred in November for males, and in September to November for females. Conclusions Extreme decreases in traffic accident mortalities can be explained by people staying home. Abnormal increases in accident mortalities in summer might be explained by the heat. The increases might also be related to wearing face masks. Suicide results suggest that females are especially vulnerable to the social environment created by the preventive measures against COVID-19. Key messages COVID-19 measures might have affected the physical, mental, and social well-being of elderly people. Acknowledgements This study was supported by Mitsui Sumitomo Insurance Welfare Foundation.