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Purpose Social isolation and loneliness have been long-standing public health concerns, and the coronavirus disease 2019 (COVID-19) pandemic has exacerbated these issues. Therefore, this study aimed to investigate the associations of social isolation and loneliness during the pandemic with experience of COVID-19 infection and hospitalization in the Japanese population. Methods Data were sourced from the Japan COVID-19 and Society Internet Survey (JACSIS), a large-scale, web-based national survey of individuals aged 15–79. This study used JACSIS data from 2020 to 2022, representing the first and third years of the pandemic. Social isolation was measured by the frequency of direct and indirect contact with people other than co-residing family members. Loneliness was evaluated using the UCLA Loneliness Scale, while COVID-19 infection and hospitalization were self-reported. Results A total of 13,612 individuals were included, of whom 1.5% had experienced hospital admission due to COVID-19, and 9.3% were infected but not hospitalized. Social isolation was inversely associated with COVID-19 infection risk (odds ratio = 0.77; 95% confidence interval: 0.66–0.90), while a higher level of loneliness was related to hospitalization (odds ratio = 2.21; 95% confidence interval: 1.59–3.09). Sex-stratified analyses revealed stronger associations in men than women. Conclusion This study highlights the complex relationship between psychosocial factors and infectious disease outcomes, underscoring the need for comprehensive approaches to address the multifaceted challenges posed by global health crises.

People are living longer, and our life has become more digital. Hence, the benefits from digital technology, including economic growth, increasing labor productivity, and ensuring health equity in the face of an aging population emerged as a vital topic for countries around the world. Japan, the Republic of Korea (ROK), Singapore, and Thailand are in the top ten rankings in terms of information and communication technology (ICT) development within the Asia Pacific Region and all are facing challenges of population aging. Well-designed national ICT policy and health promotion policies enabled the countries to make significant progress and development in terms of digitalization and healthy aging. This paper aims to answer questions regarding digitization and health promotion: when it started, how it is going, what are the achievements, and what it holds for the future, considering healthy aging and digitalization by reviewing the national ICT policy and health promotion policies of Japan, Korea, Singapore, and Thailand. This paper is expected to help readers build a comprehensive understanding of each country’s journey towards building a healthy aging digital society. Furthermore, we hope this paper can be a source for countries to exchange experiences and learn from each other with a joint goal of building a healthy aging digital society.

This paper introduces a Markov chain-based approach for the analysis and optimization of spare-management policies in large-scale satellite constellations. Focusing on the direct strategy, we model spare replenishment as a periodic-review reorder-point/order-quantity policy, where spares are deployed directly to constellation planes. The stochastic behavior of satellite failures and launch vehicle lead times is captured through Markov representations of both failure and replenishment dynamics. Based on this efficient and accurate framework, we construct and solve an optimization problem aimed at minimizing operational costs. The effectiveness of the proposed method is demonstrated through a case study using a real-world mega-constellation.

This paper presents a method for analyzing and designing an optimal spare-management policy in large-scale satellite constellations using a Markov chain model. To capture the stochastic nature of satellite failures and launch vehicle lead times, we adopt Markov chains to model both failure and replenishment processes. We reinvestigate an indirect spare strategy, modeled as a multi-echelon periodic-review reorder-point/order-quantity policy, in which spares are first delivered to parking orbits and then transferred to constellation planes. The stock levels in constellation and parking orbits are each modeled as independent Markov chains, and a fixed-point iteration yields a consistent joint stationary solution that describes the strategy's average behavior. This approach accurately captures the stochastic interplay within a multi-echelon model driven by orbital mechanics, avoiding the aggregation assumptions of prior works and remaining valid across a wider operating domain. Building on this fast, accurate analysis, we formulate an optimization problem and solve it via a genetic algorithm. Finally, we demonstrate the practical value of both the analysis method and the optimization framework in a real-world mega-constellation case study.

Understanding the growth and evolution of social networks is an important area of study, as these networks form the foundation for many popular online services such as social networking sites (SNS) and online games. However, previous models developed to explain the growth mechanisms of these networks have struggled to accurately reproduce certain behaviors that are frequently observed in real data, such as waves of novelty, in which new individuals or topics receive more attention than existing ones for a short period of time. In this study, we introduce a new model that incorporates context information into existing agent-based models in order to more accurately capture the structure and growth dynamics of these networks. Context information is introduced through labels based on the timing of appearance and relationships with antecedent agents. New agents are first added to the network when they are called by existing agents, and at this time they are also given a label. Agents added to the network at the same time by the same agent will have the same label. These labels are used to classify agents and give them different selection probabilities. This newly introduced selection probability creates a mechanism in which new agents receive attention beyond preferential attachment. By comparing the results of our model with real data on ten metrics, we demonstrate that it is able to produce behavior that more closely resembles real data. This improved understanding of the dynamics of social networks has important implications for designing effective interventions, including strategies for user acquisition and retention.

Previous studies have primarily focused on quality of imaging in radiotherapy planning computed tomography (RTCT), with few investigations on imaging doses. To our knowledge, this is the first study aimed to investigate the imaging dose in RTCT to determine baseline data for establishing national diagnostic reference levels (DRLs) in Japanese institutions. A survey questionnaire was sent to domestic RT institutions between 10 October and 16 December 2021. The questionnaire items were volume computed tomography dose index (CTDIvol), dose–length product (DLP), and acquisition parameters, including use of auto exposure image control (AEC) or image-improving reconstruction option (IIRO) for brain stereotactic irradiation (brain STI), head and neck (HN) intensity-modulated radiotherapy (IMRT), lung stereotactic body radiotherapy (lung SBRT), breast-conserving radiotherapy (breast RT), and prostate IMRT protocols. Details on the use of motion-management techniques for lung SBRT were collected. Consequently, we collected 328 responses. The 75th percentiles of CTDIvol were 92, 33, 86, 23, and 32 mGy and those of DLP were 2805, 1301, 2416, 930, and 1158 mGy·cm for brain STI, HN IMRT, lung SBRT, breast RT, and prostate IMRT, respectively. CTDIvol and DLP values in institutions that used AEC or IIRO were lower than those without use for almost all sites. The 75th percentiles of DLP in each treatment technique for lung SBRT were 2541, 2034, 2336, and 2730 mGy·cm for free breathing, breath holding, gating technique, and real-time tumor tracking technique, respectively. Our data will help in establishing DRLs for RTCT protocols, thus reducing imaging doses in Japan.

Background Left ventricular outflow tract stenosis and atrioventricular valve regurgitation are often problems encountered in adulthood after complete atrioventricular septal defect repair. The surgical approach and indications for managing long-term outcomes such as left atrioventricular valve regurgitation and left ventricular outflow tract stenosis after complete atrioventricular septal defect repair have been discussed. Case presentation A 23-year-old woman with intellectual disability was diagnosed with complete atrioventricular septal defect and underwent two-patch repair without cleft closure in childhood. Follow-up examination in adulthood demonstrated moderate left-sided atrioventricular valve regurgitation and left ventricular outflow tract stenosis with a circumferential ridge (peak velocity, 3.7 m/s; pressure gradient, 54 mmHg). Intraoperative findings showed a circumferential ridge under the aortic valve, and we removed the ridge. In addition, a cleft was present at the anterior leaflet, and we completely closed the cleft. Anticoagulation therapy was not initiated, and no embolic complications occurred. Follow-up echocardiography demonstrated no ridge under the aortic valve and only mild-range left AVVR. Conclusions We successfully performed surgical treatment without valve replacement or anticoagulation therapy in a patient with poor medical compliance. Delayed reoperation leads to degeneration of the valve structure and makes more difficult to repair. Atrioventricular valve regurgitation should be evaluated in combination with based on the etiology of the regurgitation especially cleft related or not, in addition to the dilatation annulus, cleft size, and depth of the leaflet coaptation depth, and associated other valve diseases.

An inherent limitation of the Ross procedure is long-term two valve disease which will require repetitive reintervention. In this case, a 31-year-old man who had underwent Ross operation due to congenital bicuspid valve 20 years before, underwent double root replacement: valve sparing root reimplantation concomitant with the right ventricular outflow tract (RVOT) reconstruction with a bioprosthesis for severe RVOT stenosis. Although the diameter of autograft root was 42 mm and aortic insufficiency was mild, we added root surgery due to concerns regarding autograft root dilation in response to left ventricular volume load after RVOT reconstruction. The postoperative echocardiogram showed minimal aortic valve regurgitation and normal blood flow in the RVOT, and he was discharged from the hospital on the 17th day after the surgery. In this report, we present the outcomes of Valve-sparing double root replacement following Ross surgery.

Patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive dermatomyositis (DM) frequently develop rapidly progressive interstitial lung disease and may also exhibit hepatic dysfunction, yet the mechanisms of hepatic injury remain poorly defined. We investigated the roles of M2-like macrophages and complement activation in hepatic injury associated with anti-MDA5 antibody-positive DM. Liver specimens from five autopsy cases of anti-MDA5 antibody-positive DM were examined for the presence of CD80-positive M1-like and CD206-positive M2-like macrophages. To establish a model of antibody-mediated hepatic injury, human MDA5 transgenic mice were treated with in-house anti-human MDA5 monoclonal antibodies. The contribution of complement was assessed by comparing hepatic pathology between wild-type and complement component C3-deficient MDA5 transgenic mice. Liver tissues were analyzed by immunohistochemistry and western blotting, and single-cell RNA sequencing libraries were generated from snap-frozen mouse liver samples. Autopsy liver specimens demonstrated the presence of CD80-positive M1-like and CD206-positive M2-like macrophages. In human MDA5 transgenic mice, administration of anti-human MDA5 monoclonal antibodies induced hepatic injury accompanied by increased infiltration of CD206-positive M2-like macrophages. This hepatic injury was markedly attenuated in C3-deficient MDA5 transgenic mice, supporting an important role for complement activation in this model. Complement activation and the accumulation of M2-like macrophages are associated with anti-human MDA5 monoclonal antibody-induced hepatic injury in mice. These findings provide mechanistic insight into antibody-complement-macrophage interactions and suggest that modulation of complement pathways may represent a potential therapeutic approach to limit liver and systemic involvement in this disorder.

In a recent study, we showed that konjac glucomannan (KGM) inhibits rice gruel-induced postprandial increases in plasma glucose and insulin levels. To extend this research, we investigated the effects of KGM addition to rice gruel on pre- and postprandial concentrations of circulating lipoprotein lipase (LPL), glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1), hepatic triglyceride lipase (HTGL), free fatty acids (FFA), and triglycerides (TG). A total of 13 Japanese men, without diabetes, dyslipidemia, or gastrointestinal diseases, interchangeably ingested rice gruel containing no KGM (0%G), rice gruel supplemented with 0.4% KGM (0.4%G), and rice gruel supplemented with 0.8% KGM (0.8%G), every Sunday for 3 weeks. Blood samples were obtained at baseline and at 30, 60, and 120 min after ingestion to measure the abovementioned lipid parameters. Lipid parameters showed small, but significant, changes. Significant reductions were found in circulating FFA levels among all participants. Circulating TG levels significantly declined at 30 min and then remained nearly constant in the 0.8%G group but exhibited no significant difference in the 0%G and 0.4%G groups. Although circulating levels of LPL and GPIHBP1 significantly decreased in the 0%G and 0.4%G groups, they increased at 120 min in the 0.8%G group. Participants in the 0%G and 0.4%G groups showed significant decreases in circulating HTGL levels, which was not observed in the 0.8%G group. Our results demonstrate the novel pleiotropic effects of KGM. Supplementation of rice gruel with KGM powder led to TG reduction accompanied by LPL and GPIHBP1 elevation and HTGL stabilization, thereby attenuating TG metabolism.