Secondary household transmission of SARS-CoV-2: a case-control study on factors associated with reduced transmission risk.

OBJECTIVES: This study aimed to identify factors deterring secondary household transmission of SARS-CoV-2 from SARS-CoV-2-positive cohabitants. METHODS: A case-control study was conducted with 272 healthcare workers in close contact with SARS-CoV-2-positive cohabitants. Logistic regression modeling was employed to determine the factors independently associated with secondary household transmission. RESULTS: A SARS-CoV-2 infection within the past 6 months was the most protective factor against secondary household transmission (adjusted odds ratio = 0.07, 95% CI: 0.01-0.61, P <0.05). Home isolation and older age of primary index case (7-12, ≥18 years) were also associated with a reduced risk. Both monovalent and bivalent messenger ribonucleic acid booster vaccinations exhibited potential protective tendencies but were not statistically significant. Additionally, bivalent vaccines did not demonstrate a clear advantage over monovalent vaccines. CONCLUSION: A recent history of SARS-CoV-2 infection, home isolation of positive cohabitants, and older age of primary index cases were positively associated with a reduced risk of secondary household transmission. Regarding booster vaccinations, data from a single center with a limited sample size may not capture all statistically significant differences, necessitating broader studies.

Evaluation of physical and psychological status of health care workers infected with COVID-19 during a hospital outbreak in Japan.

PURPOSE: COVID-19 causes physical and psychological impacts on health care workers (HCWs), especially when it occurs during an outbreak. As there are few reports on outcomes of HCWs infected with COVID-19 during a hospital outbreak, we investigated the physical and psychological impacts on HCWs infected with COVID-19 during an outbreak in our hospital. METHODS: During the outbreak in our hospital, 231 people were infected with COVID-19 including patients, HCWs and their families. Among them, 83 HCWs were enrolled in this study. Current quality of life (QOL) was assessed with the EuroQol-visual analogue scales (EQ-VAS), and motivation to keep on working was evaluated by a 10-point analogue scale. Physiological recovery rates including return to work (RTW) period were also analyzed. RESULTS: One nurse quit work due to anxiety regarding re-infection with COVID-19. The median period to RTW from the diagnosis was 14.0 (12.0-17.0) days. Motivation to keep on working was slightly reduced, and the EQ-VAS was 75.0 (65.0-83.6). There were no significant differences in QOL and motivation between male and female HCWs, nurses and other HCWs, treatment and non-treatment group, and supplemental and non-supplemental oxygen group. The most frequent persistent symptoms at 1,3 and 6 months after infection were anosmia followed by fatigue. CONCLUSION: Although QOL and motivation to keep on working were slightly reduced, only one HCW quit work. No severe persistent symptoms were observed, and the RTW period was relatively short.

A cell wall protein (YqgA) is genetically related to the cell wall-degrading dl-endopeptidases in Bacillus subtilis.

The Gram-positive bacterium Bacillus subtilis has a thick cell wall. The cell wall contains various proteins, both for secretion and for peptidoglycan (PG) maintenance. Penicillin-binding proteins for PG synthesis, PG hydrolases (autolysins), and regulator proteins for the autolysins are the known components of the PG maintenance system. YqgA was identified as an abundant protein attached to the cell wall of B. subtilis through a proteomics analysis. The YqgA protein was localized at cell division sites during the transition period between the exponential and the stationary phases. YqgA localization was affected by mutations in the dl-endopeptidases (DLEPases), which are the autolysins involved in cell morphogenesis. Furthermore, yqgA mutations on a background of defective DLEPases led to delays in cell growth and cell morphological changes. These results demonstrate that yqgA is genetically related to the genes encoding DLEPases involved in cell morphogenesis.

Effect on blood pressure of daily lemon ingestion and walking.

Background. Recent studies suggest that the daily intake of lemon (Citrus limon) has a good effect on health, but this has not been confirmed in humans. In our previous studies, it was observed that people who are conscious of their health performed more lemon intake and exercise. An analysis that took this into account was required. Methodology. For 101 middle-aged women in an island area in Hiroshima, Japan, a record of lemon ingestion efforts and the number of steps walked was carried out for five months. The change rates (Δ%) of the physical measurements, blood test, blood pressure, and pulse wave measured value during the observation period were calculated, and correlations with lemon intake and the number of steps walked were considered. As a result, it was suggested that daily lemon intake and walking are effective for high blood pressure because both showed significant negative correlation to systolic blood pressure Δ%. Conclusions. As a result of multiple linear regression analysis, it was possible that lemon ingestion is involved more greatly with the blood citric acid concentration Δ% and the number of steps with blood pressure Δ%, and it was surmised that the number of steps and lemon ingestion are related to blood pressure improvement by different action mechanisms.

[Effect of variation of lemon intake and walking in daily life on various indicators of muscle mass and blood biochemistry in menopausal middle-aged and elderly women].

OBJECTIVES: We examined the factors considered to change body composition and blood biochemistry indicators in menopausal middle-aged and elderly women. These changes result from exercise by walking as part of their daily activities and lemon consumption by women who live on the small islands of the Seto Inland Sea, Japan's largest citrus fruit (lemon)-producing region. METHODS: Between September 2011 and March 2012, we recorded the daily lemon consumption and the number of steps taken by 101 middle-aged and elderly female lemon farmers. We also measured their body dimensions, body compositions, and blood pressure pulse wave velocity and conducted blood tests before and after the survey period. The results before and after the survey period were compared by the t-test and associations were determined on the basis of Pearson's correlation coefficient. Covariance structural analysis was carried out to determine causal associations. RESULTS: From the results of covariance structure analysis, lemon intake did not have a direct impact on each item examined. The third item, i.e., "the factors related to arteriosclerosis," was affected indirectly via citric acid and fatigue, and anticoagulation was shown. The fourth item, i.e., "the factors related to maintenance of muscle mass," which is affected by menopausal years and the change in walking speed, was shown to be associated with the second item, i.e., "the factors related to lipid metabolism." Menopausal years affected the first, third and fourth items. CONCLUSIONS: Lemon intake did not have a direct impact on each item. Lemon has been shown to indirectly affect the third item through citric acid. Walking affected the second item, the level of total cholesterol, such as HDL cholesterol, through the fourth item. The importance of providing services that lead to sustained physical activity and a well-balanced metabolism between lipids and carbohydrates has been shown.

The major and minor wall teichoic acids prevent the sidewall localization of vegetative DL-endopeptidase LytF in Bacillus subtilis.

Cell separation in Bacillus subtilis depends on specific activities of DL-endopeptidases CwlS, LytF and LytE. Immunofluorescence microscopy (IFM) indicated that the localization of LytF depended on its N-terminal LysM domain. In addition, we revealed that the LysM domain efficiently binds to peptidoglycan (PG) prepared by chemically removing wall teichoic acids (WTAs) from the B. subtilis cell wall. Moreover, increasing amounts of the LysM domain bound to TagB- or TagO-depleted cell walls. These results strongly suggested that the LysM domain specifically binds to PG, and that the binding may be prevented by WTAs. IFM with TagB-, TagF- or TagO-reduced cells indicated that LytF-6xFLAG was observed not only at cell separation site and poles but also as a helical pattern along the sidewall. Moreover, we found that LytF was localizable on the whole cell surface in TagB-, TagF- or TagO-depleted cells. These results strongly suggest that WTAs inhibit the sidewall localization of LytF. Furthermore, the helical LytF localization was observed on the lateral cell surface in MreB-depleted cells, suggesting that cell wall modification by WTAs along the sidewall might be governed by an actin-like cytoskeleton homologue, MreB.