Naringin-induced M2 macrophage polarization facilitates osteogenesis of BMSCs and improves cranial bone defect healing in rat.

Osteoimmunology has uncovered the critical role of the immune microenvironment in the bone healing process, with macrophages playing a central part in generating immune responses via chemokine production. Naringin, a flavanone glycoside extracted from various plants, has been shown to promote osteoblast differentiation, thereby enhancing bone formation and mitigating osteoporosis progression. Current research on the osteogenic mechanism primarily focuses on the direct impact of naringin on mesenchymal stem cells, while its indirect immunoregulatory effects remain elusive. In this study, we investigated the bone defect-enhancing effects of varying naringin concentrations in vivo using a cranial bone defect model in Sprague-Dawley rats. We assessed the osteoimmune modulation capacity of naringin by exposing lipopolysaccharide (LPS)-induced RAW 264.7 macrophages to different doses of naringin. To further elucidate the underlying osteogenic enhancement mechanism, Bone Marrow Stromal Cells (BMSCs) derived from mice were treated with conditioned media from naringin-treated macrophages. Our findings indicated that naringin promotes M2 phenotype polarization in macrophages, as evidenced by the downregulation of pro-inflammatory cytokines Inducible Nitric Oxide Synthase (iNOS), interleukin (IL)-1ß, and Tumor Necrosis Factor (TNF)-α, and the upregulation of anti-inflammatory cytokine Transforming growth factor (TGF)-ß. Transcriptome analysis revealed that differentially expressed genes were significantly enriched in osteoblast differentiation and anti-inflammatory response pathways in naringin-pretreated macrophages, with the cytokines signaling pathway being upregulated. The conditioned media from naringin-treated macrophages stimulated the expression of osteogenic-related genes Alkaline phosphatase (Alp), osteocalcin (Ocn), osteopontin (Opn), and Runt-related transcription factor (Runx) 2, as well as protein expression in BMSCs. In conclusion, naringin alleviates macrophage inflammation by promoting M2 phenotype polarization, which in turn enhances the osteogenic differentiation of BMSCs, contributing to its bone healing effects in vivo. These results suggest that naringin holds significant potential for improving bone defect healing through osteoimmune modulation.

The health benefit of physical exercise on COVID-19 pandemic: Evidence from mainland China.

OBJECTIVES: Our study aims to investigate the health benefit of regular physical exercise participation on a series of COVID-19 outcomes including COVID-19 morbidity, mortality, and cure rate. METHODS: Prefecture-level panel data related to physical exercise and the COVID-19 pandemic in China were collected from January 1 to March 17, 2020, (N = 21379). Multiple linear regression was conducted, and the ordinary least squares technique was used to estimate the coefficient. RESULTS: It was shown that regular sports participation significantly negatively affected COVID-19 morbidity (estimate = -1.1061, p<0.01) and mortality (estimate = -0.3836, p<0.01), and positively affected cure rate (estimate = 0.0448, p<0.01), implying that engaging in physical exercise regularly does have a significant positive effect on COVID-19 outcomes. Then, we explored the heterogeneity of the effect of physical exercise on areas with different risk levels and it was revealed that the effect of physical exercise was more pronounced in high-risk areas in terms of morbidity (estimate = -1.8776, p<0.01 in high-risk areas; estimate = -0.0037, p<0.01 in low-risk areas), mortality (estimate = -0.3982, p<0.01 in high-risk areas; estimate = -0.3492, p<0.01 in low-risk areas), and cure rate (estimate = 0.0807, p<0.01 in high-risk areas; 0.0193 = -0.0037, p<0.05 in low-risk areas). CONCLUSIONS: Our results suggest that regularly engaging in physical exercise before the pandemic has positive health effects, especially in the case of a more severe epidemic. Therefore, we urge readers to actively engage in physical exercise so that we can reduce the risks in the event of a pandemic.

Sports Participation and Anti-Epidemic: Empirical Evidence on the Influence of Regular Physical Activity on the COVID-19 Pandemic in Mainland China.

This study aims to investigate the effects and influencing mechanisms of regular physical activity (RPA) on the COVID-19 pandemic. Daily data from 279 prefecture-level cities in mainland China were collected from 1 January to 17 March 2020. A two-way fixed-effects model was used to identify the causal relationship between physical activity and COVID-19, while also considering factors such as patterns of human behavior and socioeconomic conditions. The instrumental variable (IV) approach was applied to address potential endogeneity issues for a more accurate causal identification, and the mediating effect model was applied to examine the mechanisms of the influence of physical activity on the epidemic. We found that regular physical activity significantly improves individual immunity, which, in turn, leads to a reduction in the probability of being infected with COVID-19. Furthermore, we investigated the heterogeneity of the influence, finding that the negative impact of physical activity on the pandemic is more pronounced in the absence of adequate medical resources, strong awareness of prevention among residents, and fully implemented public health measures. Our results provide empirical evidence for the mechanisms of influence of physical activity on the pandemic. We would suggest that not only should physical activity be actively practiced during the pandemic, but also long-term regular exercise habits should be consciously cultivated to improve the ability of the individual immune system to better cope with sudden outbreaks of emerging infectious diseases.

Research on the Influence of Information Diffusion on the Transmission of the Novel Coronavirus (COVID-19).

With the rapid development of the Mobile Internet in China, epidemic information is real-time and holographic, and the role of information diffusion in epidemic control is increasingly prominent. At the same time, the publicity of all kinds of big data also provides the possibility to explore the impact of media information diffusion on disease transmission. We explored the mechanism of the influence of information diffusion on the transmission of COVID-19, developed a model of the interaction between information diffusion and disease transmission based on the Susceptible-Infected-Recovered (SIR) model, and conducted an empirical test by using econometric methods. The benchmark result showed that there was a significant negative correlation between the information diffusion and the transmission of COVID-19. The result of robust test showed that the diffusion of both epidemic information and protection information hindered the further transmission of the epidemic. Heterogeneity test results showed that the effect of epidemic information on the suppression of COVID-19 is more significant in cities with weak epidemic control capabilities and higher Internet development levels.

Can urban rail transit reduce haze pollution? A spatial difference-in-differences approach.

This paper explores the influence and mechanism of urban rail transit on haze pollution in mainland China. Based on the satellite remote sensing dataset released by the Earth Observing System of Data and Information System (EOSDIS) of the National Aeronautics and Space Administration (NASA) and urban rail transit network data of Robert Schwan, the prefecture-year urban rail transit and haze concentration-related dataset from 2001 to 2018 is collected. Considering the significant spatial autocorrelation of urban haze pollution, a spatial difference-in-differences (SDID) approach is applied to empirically investigate the influence of urban rail transit on haze pollution. The results show that the connection of urban rail transit significantly reduces the urban PM2.5 concentration, and the effect has significant regional heterogeneity. Furthermore, it is found that the substitution effect on motor vehicles is the mechanism in which urban rail transit impacts haze pollution. Based on our findings, accelerating urban rail transit network support, appropriately relaxing the subway application in some large cities, and taking comprehensive measures to attract more residents to choose subway travel is proposed.

Are Sports Champions Also Anti-Epidemic Heroes? Quantitative Research on the Influence of Sports Champions' Demonstration Effect on the COVID-19 Epidemic in China.

What kind of role do sports champions play in the COVID-19 epidemic? Do they contribute to the mitigation of the epidemic by some pathway? In this paper, we empirically explore the influence and mechanism of the demonstration effect of sports champions upon the COVID-19 epidemic using COVID-19-related dataset of prefecture-level cities in China from 1 January 2020 to 17 March 2020. The two-way fixed effect model of econometrics is applied to estimate the result, the instrumental variable approach is adopted to address potential endogeneity issues, and socio-economic factors including public health measures, residents' self-protection awareness, effective distance from Wuhan are also taken into consideration. The results show that the demonstration effect of champions in major sporting events increases the participation in physical exercise, which in turn reduces the possibility of being infected with the epidemic. An increase of one gold medal results in a 0.93% increase in the sports population, then leads to a 3.58% decrease in the cumulative case growth rate (p < 0.01). Further, we find that the effect is greater in regions with developed economies and abundant sports resources. Interestingly, it is greater in regions with less attention to sports, which again confirms the role of the demonstration effect.

Market integration and green economic growth-recent evidence of China's city-level data from 2004-2018.

Very few studies exist in rationalizing comprehensively the relationship between market integration and green economic growth in China. This paper tries to answer the question whether and how market integration influences regional green economic growth in China. Based on the panel data of 285 city-level regions from year 2004 to 2018 in China, this paper develops explanatory mechanism and discusses the influence theoretically and empirically. To advance the analysis, we construct market integration indicator through relative price variance method based on commodity retail price index and employ the Malmquist-Luenberger (ML) productivity index and DEA-SBM (data envelopment analysis-slacks-based measure) model to evaluate green total factor productivity (GTFP) as indicator for green economic growth. Our empirical findings are: (1) Apparent regional imbalance exists in both the development of market integration and green growth and gaps are expanding from year 2004 to 2018. (2) Market integration promotes regional green growth significantly. (3) Mechanism analysis illustrates that market integration fosters green growth through economies of scale effect, composition effect and spillover effect, respectively. (4) Heterogeneous analysis suggests that the influence from market integration on green growth varies depending on region's difference in traffic situation and in overall development level.

Does lower regional density result in less CO2 emission per capita? : Evidence from prefecture-level administrative regions in China.

Regional density is a useful tool for analyzing regional spatial structure as well as a good starting point for analyzing regional CO2 emissions per capita. This paper empirically analyzes the relationship between regional density and per capita CO2 emissions in China's prefecture-level administrative regions. We improve the CO2 emission measurement method for prefecture-level administrative regions and estimate the per capita CO2 emissions of 252 prefectural-level cities in China from 2003 to 2013. Using panel fixed effect model regression, and taking the terrain roughness index as an instrumental variable to solve endogeneity, we find that the relationship between regional density and per capita CO2 emissions presents in an inverted U-shape, per capita CO2 emissions first increase with the increase of regional density, and after reaching the turning point, it decreases with regional density. In a mechanism test, analyzing the interaction terms between regional density and industrial structure, and regional density and urbanization level respectively. We found that industrial structure and urbanization are important mechanisms for regional density to affect CO2 emissions. In order to reduce per capita CO2 emissions, we propose corresponding policy implications for the regions in different positions of the "U" curve.

The influence of weather conditions on the COVID-19 epidemic: Evidence from 279 prefecture-level panel data in China.

Studying the influence of weather conditions on the COVID-19 epidemic is an emerging field. However, existing studies in this area tend to utilize time-series data, which have certain limitations and fail to consider individual, social, and economic factors. Therefore, this study aimed to fill this gap. In this paper, we explored the influence of weather conditions on the COVID-19 epidemic using COVID-19-related prefecture-daily panel data collected in mainland China between January 1, 2020, and February 19, 2020. A two-way fixed effect model was applied taking into account factors including public health measures, effective distance to Wuhan, population density, economic development level, health, and medical conditions. We also used a piecewise linear regression to determine the relationship in detail. We found that there is a conditional negative relationship between weather conditions and the epidemic. Each 1 °C rise in mean temperature led to a 0.49% increase in the confirmed cases growth rate when mean temperature was above -7 °C. Similarly, when the relative humidity was greater than 46%, it was negatively correlated with the epidemic, where a 1% increase in relative humidity decreased the rate of confirmed cases by 0.19%. Furthermore, prefecture-level administrative regions, such as Chifeng (included as "warning cities") have more days of "dangerous weather", which is favorable for outbreaks. In addition, we found that the impact of mean temperature is greatest in the east, the influence of relative humidity is most pronounced in the central region, and the significance of weather conditions is more important in the coastal region. Finally, we found that rising diurnal temperatures decreased the negative impact of weather conditions on the spread of COVID-19. We also observed that strict public health measures and high social concern can mitigate the adverse effects of cold and dry weather on the spread of the epidemic. To the best of our knowledge, this is the first study which applies the two-way fixed effect model to investigate the influence of weather conditions on the COVID-19 epidemic, takes into account socio-economic factors and draws new conclusions.

Do prevention and control measures work? Evidence from the outbreak of COVID-19 in China.

In the face of COVID-19, an emerging infectious disease, in addition to the classic non-pharmaceutical interventions such as isolation, quarantine, social, China also adopted strict mobility restrictions including inter-administrative districts travel restrictions, which severely affect residents' lives and almost completely stopped production activities at cost of a huge economic and social cost. In this paper, we develop the model of Dirk Brockmann and Dirk Helbing (2013) to theoretically explain the impact mechanism of prevention and control measures on the spread of the epidemic. Then, we divide the measures taken in China into two categories: mobility restrictions and other non-pharmacological interventions (O-NPI), and apply econometric approach to empirically test the effects of them. We find that although both of the two measures play a good role in controlling the development of the epidemic, the effect shows significant difference in different regions, and both the two measures had no significant effects in low-risk regions; Further, we prove that measures taken in a low-risk region is mainly against the imported cases, while a high-risk region has to defend against both imported cases and spread from within; The rapid and accurate transmission of information, a higher protection awareness of the public, and a stronger confidence of residents can promote the implementation of the measures.

Traffic control and social distancing evidence from COVID-19 in China.

We collected COVID-19 epidemiological and epidemic control measures-related data in mainland China during the period January 1 to February 19, 2020, and empirically tested the practical effects of the epidemic control measures implemented in China by applying the econometrics approach. The results show that nationally, both traffic control and social distancing have played an important role in controlling the outbreak of the epidemic, however, neither of the two measures have had a significant effect in low-risk areas. Moreover, the effect of traffic control is more successful than that of social distancing. Both measures complement each other, and their combined effect achieves even better results. These findings confirm the effectiveness of the measures currently in place in China, however, we would like to emphasize that control measures should be more tailored, which implemented according to each specific city's situation, in order to achieve a better epidemic prevention and control.

Research on the Influence of Information Diffusion on the Transmission of the Novel Coronavirus (COVID-19)

With the rapid development of mobile Internet in China, the information of the epidemic is full-time and holographic, and the role of information diffusion in epidemic control is increasingly prominent. At the same time, the publicity of all kinds of big data also provides the possibility to explore the impact of media information diffusion on disease transmission. This paper explores the mechanism of the influence of information diffusion on the spread of the novel coronavirus, develops a model of the interaction between information diffusion and disease transmission based on the SIR model, and empirically tests the role and mechanism of information diffusion in the spread of COCID-19 by using econometric method. The result shows that there was a significant negative correlation between the information diffusion and the spread of the novel coronavirus; The result of robust test shows that the spread of both epidemic information and protection information hindered the further spread of the epidemic.

Treatment of radiation-induced acute intestinal injury with bone marrow-derived mesenchymal stem cells.

The aim of the present study was to investigate the ability of bone marrow-derived mesenchymal stem cells (BMSCs) to repair radiation-induced acute intestinal injury, and to elucidate the underlying repair mechanism. Male Sprague-Dawley rats were subjected to whole abdominal irradiation using a single medical linear accelerator (12 Gy) and randomly assigned to two groups. Rats in the BMSC-treated group were injected with 1 ml BMSC suspension (2×106 cells/ml) via the tail vein, while the control group rats were injected with normal saline. BMSCs were identified by detecting the expression of CD29, CD90, CD34 and CD45 using flow cytometry. The expression of the cytokines stromal cell-derived factor 1 (SDF-1), prostaglandin E2 (PGE2) and interleukin (IL)-2 was detected using immunohistochemical techniques. Plasma citrulline concentrations were evaluated using an ELISA kit. Rat general conditions, including body weight, and changes in cellular morphology were also recorded. The results suggested that BMSCs exerted a protective effect on radiation-induced acute intestinal injury in rats. The histological damage was rapidly repaired in the BMSC-treated group. In addition, the BMSC-treated group showed significantly reduced radiation injury scores (P<0.01), mildly reduced body weight and plasma citrulline levels, significantly more rapid recovery (P<0.01), significantly reduced expression of the cytokines PGE2 and IL-2 (P<0.05) and significantly increased SDF-1 expression (P<0.01) compared with the control group. In summary, the present results indicate that BMSCs are able to effectively reduce inflammation and promote repair of the structure and function of intestinal tissues damaged by radiation exposure, suggesting that they may provide a promising therapeutic agent.