Nanocrystal formulations have been explored to deliver poorly water-soluble drug molecules. Despite various studies of nanocrystal formulation and delivery, much more understanding needs to be gained into absorption mechanisms and kinetics of drug nanocrystals at various levels, ranging from cells to tissues and to the whole body. In this study, nanocrystals of tetrakis (4-hydroxyphenyl) ethylene (THPE) with an aggregation-induced emission (AIE) property was used as a model to explore intracellular absorption mechanism and dissolution kinetics of nanocrystals. Cellular uptake studies were conducted with KB cells and characterized by confocal microscopy, flow cytometry, and quantitative analyses. The results suggested that THPE nanocrystals could be taken up by KB cells directly, as well as in the form of dissolved molecules. The cellular uptake was found to be concentration- and time-dependent. In addition, the intracellular THPE also could be exocytosed from cells in forms of dissolved molecules and nanocrystals. Kinetic modeling was conducted to further understand the cellular mechanism of THPE nanocrystals based on first-order ordinary differential equations (ODEs). By fitting the kinetic model against experimental measurements, it was found that the initial nanocrystal concentration had a great influence on the dynamic process of dissolution, cellular uptake, and exocytosis of THPE nanocrystals. As the nanocrystal concentration increased in the culture media, dissolution of endocytosed nanocrystals became enhanced, subsequently driving the efflux of THPE molecules from cells.

Objective:To evaluate the prevention and control effect of coal-burning-borne endemic fluorosis in Ankang City of Shaanxi Province, so as to provide a scientific basis for formulating precise prevention and control strategies in the future.Methods:From 2019 to 2023, according to the requirements of the "Monitoring Program of Shaanxi Province for Coal-burning-borne Endemic Fluorosis (2019 Edition)", full coverage monitoring was carried out in all affected villages in seven affected counties under the jurisdiction of Ankang City. Using the simple random sampling method, 30 households in each affected village were selected to investigate the use of improved stoves and the formation of health-related behaviors. All children aged from 8 to 12 in the village were examined for the prevalence of dental fluorosis. At the same time, 6 monitoring villages were selected in 2019, and 8 monitoring villages were selected in 2023 to collect real-time urine samples from children aged 8 - 12 for determination of urinary fluoride level. The evaluation for control and elimination of disease areas was carried out in accordance with the "Evaluation Approach for Control and Elimination of Priority Endemic Diseases (2019 Edition)".Results:From 2019 to 2023, a total of 203 880 households were monitored, the rate of qualified improved stoves and the correct use rate of qualified improved stoves were more than 95.00%. The utilization rate of improved stoves decreased from 16.34% (6 584/40 290) in 2019 to 8.89% (3 706/41 700) in 2023, showing a decreasing trend year by year (χ 2trend = 3 400.37, P < 0.001). The utilization rate of clean energy increased from 82.52% (33 247/40 290) in 2019 to 94.36% (39 350/41 700) in 2023, showing an upward trend year by year (χ 2trend = 7 506.09, P < 0.001). The correct drying rate of corn and pepper for human consumption were 100.00%. A total of 455 327 children aged 8 - 12 were examined, and 2 301 cases of dental fluorosis were diagnosed, with a detection rate of 0.51%. Children with dental fluorosis were mainly extremely mild and mild, accounting for 94.87% (2 183/2 301). The dental fluorosis index was 0.012, indicating no trend of fluorosis prevalence. The detection rate of dental fluorosis in children decreased from 0.81% (765/94 537) in 2019 to 0.24% (204/86 066) in 2023, showing a declining trend year by year (χ 2trend = 375.45, P < 0.001). The geometric mean urinary fluoride levels of children aged 8 to 12 in 2019 and 2023 were 0.48 and 0.42 mg/L, respectively, with statistically significant differences between groups ( Z = - 3.05, P = 0.002). As of 2023, 1 390 affected villages had met the elimination criteria. Conclusions:The prevention and control of coal-burning-borne endemic fluorosis in Ankang City has achieved remarkable results, with all seven affected counties reaching the elimination standard. In the future, we should strengthen the management of high fluoride coal mines, continue to promote the use of clean energy, strengthen health promotion and disease monitoring, and continuously consolidate and improve the results of prevention and control.

Objective:To study the epidemiological characteristics of mortality and cause of death composition in patients with coal-burning-borne endemic arsenism in Ankang City, Shaanxi Province.Methods:Mortality data of patients with coal-burning-borne endemic arsenism in Ankang City from 2018 to 2023 were collected from the Shaanxi Provincial Endemic Disease Prevention and Control Information Management Platform and the National Death Cause Information Registration System. Crude and standardized mortality rates, years of life lost (YLL) due to premature death were calculated, and the population and regional distribution characteristics of death cases were analyzed. Causes of death were classified and analyzed according to the International Classification of Diseases (ICD-10) category codes.Results:From 2018 to 2023, a total of 610 patients with coal-burning-borne endemic arsenism died in Ankang City, Shaanxi Province. The average annual crude mortality rate was 5.20/100 000. The average age of death for patients was 77.78 years old, and the mortality rate showed an upward trend with age (χ 2tend = 1 163.82, P < 0.001), with a significant increase in patients over 60 years old. The male to female ratio was 3.18∶1.00 (464/146). Among the seven diseased districts and counties, Langao County had the highest mortality rate. The YLL was 6 241.68 person-years. The top four causes of death among these cases circulatory system diseases, respiratory system diseases, malignant tumors, and injuries differed from those of the entire population in Ankang City, with respiratory system diseases being more prominently ranked. Conclusions:The death cases of coal-burning-borne endemic arsenism in Ankang City are mainly elderly males, and are more common in Langao County. There are various causes of death, coexisting with circulatory system diseases, respiratory system diseases, malignant tumors, and injuries.

The eutR gene deletion mutant of Salmonella enteritidis was successfully constructed by homologous recombination.Through the study of its biochemical characteristics,motility,resist-ance to stress in vitro and survival ability in RAW 264.7 cells,it was found that the biochemical characteristics and motility of the eutR gene deletion mutant of Salmonella enteritidis had no sig-nificant change compared with the wild type of Salmonella enteritidis.The ability of eutR gene de-letion strain of Salmonella enteritidis to resist acid,alkali and oxidation was significantly reduced,while the ability to resist heat was not significantly changed;the survival ability of eutR gene dele-tion strain in RAW 264.7 cells was significantly reduced compared with the wild type.In order to further analyze the effect of eutR gene on the expression of virulence factors of Salmonella enterit-idis,the relative expression levels of invH,ssav,ssrA,xthA,orf245,sodC,lrp,mrr1 and hflk virulence genes of the deletion strain and the wild strain were detected by SYBR Green PCR.It was found that the expression of the virulence factors mentioned above in the eutR gene deletion strain of Salmonella enteritidis was significantly down-regulated compared with that in the wild-type strain.The LD50 of the eutR gene-deleted strain of Salmonella enteritidis was determined by ani-mal experiments,and the results showed that the LD50 of the eutR gene-deleted strain was higher than that of the wild-type strain,indicating that the eutR gene could affect the virulence of Salmonella.This study clarified the effect of eutR gene on the survival ability,some biological characteristics and virulence of Salmonella enteritidis in macrophages,and provided a new gene knockout target for the development of attenuated Salmonella enteritidis genetic engineering vac-cine.