Objective: To analyze the distribution characteristics of fluoride and trichloromethane in drinking water in rural schools in Guizhou Province and assess their health risks, so as to provide a scientific basis for ensuring the safety of drinking water in rural schools. Methods: During the dry season (March to May) and wet season (July to September) of 2020 to 2022, 788 rural primary and secondary schools in agricultural counties (districts) in Guizhou Province were selected for investigation by using a direct sampling method. A total of 1 566 drinking water samples were collected from these schools, and the mass concentrations of fluoride and trichloromethane in the water samples were detected. The Mann-Whitney U test was used for intergroup comparison, and a health risk assessment model was employed to evaluate the health risks of students oral intake of fluoride and trichloromethane. Results: From 2020 to 2022, the mass concentrations of fluoride and trichloromethane in the drinking water of rural schools in Guizhou Province all met the standards, and the ranges were no detection to 0.99 mg/L and (no detection to 0.06)×10 -3 mg/L, respectively. The mass concentrations of fluoride in dry and wet seasons were 0.05(0.05,0.10), 0.05(0.05,0.10) mg/L, the mass concentrations of trichloromethane were [0.02(0.02,1.00)]×10 -3 , [0.02(0.02,1.00)]×10 -3 mg/L, the mass concentrations of fluoride in factory water and terminal water were 0.05(0.05,0.05), 0.05(0.05,0.10) mg/L, and the differences were not statistically significant ( Z=-0.04, -0.88, - 0.98 , P >0.05). There was a statistically significant difference in the mass concentration of trichloromethane between factory water and peripheral water [0.02(0.02,0.02)×10 -3 , 0.02(0.02,1.05)×10 -3 mg/L]( Z=-2.16, P < 0.05 ). The non-carcinogenic risk assessment values for students oral exposure to fluoride and trichloromethane were in the range of 0.01(0.01,0.03)-0.03(0.03,0.06) and [0.26( 0.26 ,14.54)]×10 -4 -[0.52(0.52,48.62)]×10 -4 , respectively, all of which were at acceptable levels; the carcinogenic risk assessment values for oral exposure to trichloromethane were in the range of [0.08(0.08, 4.51 )]×10 -7 -[0.16(0.16,15.07)]×10 -7 , indicating a low risk. Conclusions The health risks of students expore to fluoride and trichloromethane in drinking water in rural schools of Guizhou Province are low. It is necessary to strengthen the standardized management of disinfection in some rural drinking water projects and the monitoring of fluoride in water sources to reduce the exposure risk to children.

OBJECTIVE To evaluate the long-term cost-effectiveness of canagliflozin or semaglutide in patients with type 2 diabetes mellitus（T2DM）poorly controlled with metformin. METHODS Based on the perspective of China’s health system， a Markov model was used to calculate the long-term costs and utilities of canagliflozin or semaglutide combined with metformin for T2DM patients in China for 30 years based on the data from SUSTAIN 8 study. The incremental cost-effectiveness ratio（ICER） and incremental net monetary benefit （INMB） were calculated using one time the 2024 per capita gross domestic product（GDP） as the willingness-to-pay（WTP） threshold. One-way sensitivity analysis， probability sensitivity analysis and scenario analysis were conducted to confirm the stability of the conclusions. RESULTS Compared with canagliflozin + metformin， ICER of semaglutide combined with metformin was 260 485.67 yuan/quality-adjusted life year （QALY），which was higher than the WTP threshold set in this study （95 749 yuan/QALY），and the corresponding INMB was －61 576.24 yuan，indicating that the canagliflozin + metformin regimen was more cost-effective. The cost of diabetes without complications treatment in the semaglutide + metformin group had the greatest influence on INMB，but changes in parameters within the selected range did not drive decision reversal. With the increasing of WTP threshold，the economic acceptability of semaglutide + metformin regimen increased. Under the current WTP threshold，the annual cost of semaglutide should be reduced by 42.95% to make the semaglutide + metformin regimen more cost- effective. CONCLUSIONS From the perspective of China’s health system， canagliflozin + metformin is more cost-effective than semaglutide + metformin for T2DM patients yueru. with poor glycemic control with metformin alone.

ObjectiveTo explore whether the mechanism of Shuangshen Ningxin capsules （SSNX） in alleviating myocardial ischemia-reperfusion injury （MIRI） in rats is related to the regulation of mitochondrial fission and fusion. MethodThis study focused on Sprague Dawley （SD） rats and ligated the left anterior descending branch of the coronary artery to construct a rat model of MIRI. The rats were divided into the sham operation group， model group， SSNX group （90 mg·kg^-1） and trimetazidine group （5.4 mg·kg^-1）. The activity of superoxide dismutase （SOD） and the content of malondialdehyde （MDA） were detected by micro method. Changes in mitochondrial membrane potential （△Ψm） and the degree of mitochondrial permeability transition pore （mPTP） opening were detected by the chemical fluorescence method. The intracellular adenosine triphosphate （ATP） level was detected by the luciferase assay. The messenger ribonucleic acid （mRNA） and protein expression levels of mitochondrial fission and fusion related factors dynamin-related protein 1 （DRP1）， mitochondrial fission 1 protein （FIS1）， optic atrophy protein 1 （OPA1）， mitochondrial outer membrane fusion protein 1 （MFN1）， and MFN2 were detected by real-time polymerase chain reaction （real-time PCR） and Western blot. ResultCompared with the sham operation group， the model group showed a decrease in serum SOD activity and an increase in MDA content. The opening level of mPTP， the level of △Ψm and ATP content decreased， the protein expressions of mitochondrial fission factors DRP1 and FIS1 increased， and the protein expressions and mRNA transcription levels of fusion related factors OPA1 and MFN1 decreased. Compared with the model group，SSNX significantly increased serum SOD activity， reduced MDA content， increased intracellular ATP level and △Ψm， reduced the opening level of mPTP， downregulated the protein expressions of mitochondrial fission factors DRP1 and FIS1， and increased the mRNA transcription levels and protein expressions of fusion related factors OPA1 and MFN1. ConclusionSSNX inhibits the expressions of mitochondrial fission factors DRP1 and FIS1， and increases the expressions of fusion related factors OPA1 and MFN1， inhibiting mitochondrial fission and increasing mitochondrial fusion， thereby alleviating MIRI.

ObjectiveTo describe the epidemic characteristics of COVID-19 after policy adjustment from “Category B notifiable disease with category A management” to “Category B notifiable disease with category B management”， and to explore the protective effect of previous infection with SARS-CoV-2 on common symptoms of reinfection. MethodsHealthcare workers infected with SARS-CoV-2 in a grade A tertiary hospital in Shanghai were included in the study from December 4， 2022 to January 11， 2023. Data on demographic characteristics， clinical symptoms， medical history， and COVID-19 vaccination history were collected. We determined the epidemiological curve and characteristics， and then compared the difference in the severity of clinical symptoms between primary and reinfection subjects. ResultsA total of 2 704 cases were included in the study， of which 45 had reinfection， 605 （22.4%）were males， 608 （22.5%）were doctors， 1 275 （47.2%） were nurses， and 2 351 （86.9%） received ≥3 doses of COVID-19 vaccination. The average age of these healthcare workers was （34.9±9.1） years old. The number of cases with mild/moderate illness， asymptomatic infection， fever， headache， dry cough， expectoration， and chest tightness were 2 704 （100.0%）， 92 （3.4%）， 2 385 （88.2%）， 2 066 （76.4%）， 1 642 （60.7%）， 1 807 （66.8%）， and 439 （16.2%）， respectively. Reinfection was a protective factor for fever （OR=0.161， P<0.001）， headache （OR=0.320， P<0.001）， and peak body temperature （β=-0.446， P<0.001）. ConclusionFollowing the COVID-19 policy adjustment as a category B notifiable disease， healthcare workers at a grade A tertiary hospital in Shanghai predominantly experiences mild to moderate COVID-19 symptoms. Reinfection results in milder clinical manifestations， with a lower proportion of being asymptomatic.

Objective To design a mobile personnel radiation protection equipment for operation in environments with high radiation such as spent fuel reprocessing plants, to achieve simultaneous protection against γ radiation, neutron radiation, and radioactive aerosol, to reduce the internal and external exposure dose of radioactive workers, and to meet the requirement of operation for two hours. Methods The core parts of the mobile personnel radiation protection equipment included a shielding chamber and a respiratory maintenance system. An automated chassis was used for the movement and lifting of the shielding chamber. MCNP software was used to simulate and calculate the protective effects of shielding chamber made of different materials and material thicknesses. Experimental verification of the shielding chamber design was conducted. Mathematical models were established to describe the variations in the content of various gases in the chamber with personnel operation time. A respiratory maintenance system, a harmful gas absorption device, and an automated mobile chassis were designed. Results The shielding chamber made of polyethylene with a thickness of 80 mm achieved an 80% neutron shielding rate. The respiratory maintenance system could support workers for 2 hours of operation inside the equipment. The mobile chassis allowed operation of the equipment with one person. Conclusion This mobile personnel radiation protection equipment can solve the problem in simultaneous protection against γ radiation, neutron radiation, and radioactive aerosol. The equipment can provide radiation protection for radioactive workers, reduce exposure dose, and reduce personnel burden. This system provides technical means for the operation and maintenance of equipment in high-radiation sites such as spent fuel reprocessing plants.

Objective:To discuss the effect of human umbilical cord mesenchymal stem cells culture supernatant(hUCMSCs-Sup)on the proliferation,apoptosis,and endometrium receptivity of the human endometrial stromal cells(hEndoSCs)treated with mifepristone(Ms),and to clarify the possible mechanism.Methods:The hEndoSCs were cultured in vitro and divided into control group and 40,60,80,and 100 μmol·L-1 Ms groups.The survival rates of the cells in various groups were detected by MTT assay.The hEndoSCs were divided into control group,40 μmol·L-1 Ms group,and 60 μmol·L-1 Ms group.The apoptotic rates of the cells in various groups were detected by flow cytometry;the expression levels of apoptosis-related protein B-cell lymphoma-2(Bcl-2)and Bcl-2-associated X protein(Bax)proteins in the cells in various groups were detected by Western blotting method,and the ratio of Bcl-2/Bax was calculated.After treated with hUCMSCs-Sup,the hEndoSCs were divided into control group,Ms group,Ms+hUCMSCs-Sup group,and Ms+hUCMSCs-Sup+3-methyladenine(3-MA)group.The survival rates of the cells in various groups were detected by MTT assay;the apoptotic rates of the cells in various groups were detected by flow cytometry;the expression levels of microtubule-associated protein 1 light chain 3B-Ⅱ(LC3B-Ⅱ)and microtubule-associated protein 1 light chain 3B-I(LC3B-Ⅰ)proteins in the cells in various groups were detected by Western blotting method,and the ratio of LC3B-Ⅱ/LC3B-Ⅰwas calculated;the expression levels of endometrium receptivity marker molecules mRNA in the cells in various groups were detected by real-time fluorescence quantitative PCR(RT-qPCR)method.Results:Compared with control group,the survival rates of the cells in 40,60,80,and 100 μmol·L-1 Ms groups were significantly decreased(P<0.05)in a time-dependent and dose-dependent manner.Compared with control group,the apoptotic rates of the cells in 40 and 60 μmol·L-1 Ms groups were significantly increased(P<0.05),and the ratios of Bcl-2/Bax were significantly decreased(P<0.05).After treated with hUCMSCs-Sup,compared with control group,the survival rate of the cells and ratio of LC3B-Ⅱ/LC3B-Ⅰ in the cells in Ms group were significantly decreased(P<0.05),the apoptotic rate was significantly increased(P<0.05),and the expression levels of homeobox A10(HOXA10),leukemia inhibitory factor(LIF),and integrin subunit beta 3(ITGB3)mRNA in the cells were significantly decreased(P<0.05);compared with Ms group,the survival rate of the cells and ratio of LC3B-Ⅱ/LC3B-Ⅰin the cells in Ms+hUCMSCs-Sup group were significantly increased(P<0.05),the apoptotic rate was significantly decreased(P<0.05),and the expression levels of HOXA10,LIF,and ITGB3 mRNA in the cells were significantly increased(P<0.05);compared with Ms+hUCMSCs-Sup group,the survival rate of the cells and ratio of LC3B-Ⅱ/LC3B-Ⅰ in the cells in Ms+hUCMSCs-Sup+3-MA group were significantly decreased(P<0.05).Conclusion:hUCMSCs-Sup can increase the survival rate and decrease the apoptotic rate of the hEndoSCs after treated with Ms,and increase the endometrium receptivity,and its mechanism may be associated with the activation of autophagy of the hEndoSCs by hUCMSCs-Sup.

ObjectiveTo observe the effects of the kidney-tonifying and blood-activating prescription on the Wnt/β-catenin signaling pathway and uterine spiral artery remodeling in a mouse model of recurrent miscarriage and to explore its underlying mechanism. MethodA mouse model of normal pregnancy was established by mating CBA/J mice with BALB/c mice. A mouse model of recurrent miscarriage was established by mating CBA/J mice with DBA/2 mice. The modeled mice of recurrent miscarriage were randomized into model， dydrogesterone， and low- and high-dose Chinese medicine groups. The mice in normal pregnancy were used as the control group. Each group consisted of 10 mice， and the drug administration lasted for 14 days. After the treatment， the embryo absorption rate of each group was recorded. Hematoxylin-eosin （HE） staining was employed to observe the pathological morphology of the uterine decidua， and the physiological transformation rate of spiral arteries （SPA） was evaluated. Real-time polymerase chain reaction （Real-time PCR） and Western blot were performed to determine the mRNA and protein levels， respectively， of matrix metalloproteinases （MMP）-2， MMP-9， vascular endothelial growth factor （VEGF）， and Wnt/β-catenin signaling pathway. ResultCompared with the control group， the model group presented increased embryo absorption rate （P<0.05）， decreased physiological transformation rate of uterine SPA （P<0.05）， cellular swelling， degeneration， and disordered arrangement in the uterine decidua tissue， and down-regulated mRNA and protein levels of key factors involved in SPA remodeling （MMP-2， MMP-9， VEGF） and the Wnt/β-catenin signaling pathway （Wnt2， β-catenin， Cyclin D₁， c-Myc） （P<0.05）. Compared with the model group， both the low- and high-dose Chinese medicine reduced embryo absorption rate （P<0.05）， increased SPA physiological transformation rate （P<0.05）， improved uterine decidua tissue morphology， and increased decidua vessel count. Furthermore， they up-regulated the mRNA and protein levels of MMP-2， MMP-9， VEGF， and proteins in the Wnt/β-catenin signaling pathway （P<0.05）. ConclusionRecurrent miscarriage is associated with impaired uterine spiral artery remodeling. The kidney-tonifying and blood-activating prescription can promote uterine spiral artery remodeling by activating the Wnt/β-catenin signaling pathway and promoting the expression of VEGF， MMP-2， and MMP-9， thus treating recurrent miscarriage.

Objective:To investigate the cognition and learning habits of different types of postgraduates and evaluate learning effect and its potential risk factors on clinical epidemiology in a medical college, so as to provide relevant data for improving the teaching method and learning effect of clinical research methods for postgraduates.Methods:A cross-sectional study design was conducted to enroll all the postgraduates of Grade 2020 in a military medical school. A self-filled questionnaire was adopted to collect data. The discrepancy of cognition and learning habits between different types of postgraduates was evaluated by univariate analysis. Discussion was conducted to clarify the potential risk factors of learning effect. t tests or Mann-Whitney U tests were conducted to test the differences between groups for continuous variables. Chi-squared tests or McNemar tests were applied to evaluate the difference between groups for categorical variables. Results:A total of 652 postgraduate students were enrolled for analysis, including 409 master students (62.7) and 243 doctoral students (37.3). The proportion of doctoral students who have heard of clinical epidemiology ( χ2=19.99, P<0.001), who have learned clinical epidemiology ( χ2=9.20, P=0.002), who are interested in ( χ2=11.41, P=0.001) and think the course is important ( χ2=10.71, P=0.001), who previewed before class( χ2=11.21, P=0.001), reviewed after class ( χ2=3.29, P=0.001) and actively discuss in class ( χ2=11.64, P=0.001) is significantly higher than that of master students, the difference was statistically significance. The average score of all the postgraduates was (5.50±1.62) points before teaching and (7.47±1.90) points after teaching, the difference was statistically significant ( t=-23.49, P<0.001). After teaching, the grades of full-time students improved more than that of part-time graduate students, there was statistical significance in the master group ( t=4.41, P<0.001), while not in the doctor group ( t=0.94, P=0.351). Conclusions:The mastery of key points on clinical epidemiology have significantly improved after teaching among the postgraduates of different types. Different teaching methods and processes should be adopted to the variety of postgraduates according to their knowledge foundations and shortcomings. Besides, standardizing their learning habits are of certain significance to improve the learning effect.

Objective:To study the correlation between serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) level and echocardiographic parameters in patients with chronic Keshan disease, providing reference for diagnosis and prognosis evaluation of chronic Keshan disease.Methods:Ninety-nine patients with chronic Keshan disease who received standardized treatment at Jingchuan County People's Hospital in Pingliang City, Gansu Province from January to December 2020 were selected. Among them, 16 patients were classified as cardiac function grade Ⅱ according to New York Heart Association (NYHA), 69 as grade Ⅲ and 14 as grade Ⅳ. The patients underwent echocardiography and their serum NT-proBNP level was measured using fluorescence immunochromatography. The differences in serum NT-proBNP levels among patients with different cardiac function grades were compared, and the correlation between cardiac function grades, serum NT-proBNP level and echocardiographic parameters was analyzed.Results:The serum NT-proBNP levels in patients with cardiac function grades Ⅱ, Ⅲ, and Ⅳ were (1 107.26 ± 268.03), (2 125.98 ± 293.02), and (8 268.59 ± 2 659.50) pg/ml, respectively. The differences among the three groups were statistically significant ( F = 13.94, P < 0.001). The serum NT-proBNP level was positively correlated with cardiac function grades ( r = 0.44, P < 0.001), left ventricular end-diastolic diameter, left ventricular end-systolic diameter, and left atrial diameter ( r = 0.45, 0.52, 0.38, P < 0.001), and negatively correlated with fractional shortening and left ventricular ejection fraction ( r = - 0.39, - 0.46, P < 0.001). Conclusions:The serum NT-proBNP level in patients with chronic Keshan disease with different cardiac function grades is different, and is positively correlated with echocardiographic parameters reflecting the degree of cardiac structural and functional impairment. The NT-proBNP level may become an early diagnostic, grading, and prognostic indicator for chronic Keshan disease.

Objective Given that psychosocial stress can contribute to a series of diseases,such as inflammatory bowel disease and irritable bowel syndrome,we aimed to establish an experimental chronic restraint mouse intestinal stress injury model as a basis for exploring the pathogenic mechanism of chronic restraint stress-induced gastrointestinal diseases,and for developing preventive and curative measures.Methods Eighteen male SPF-grade BALB/c mice were acclimatized for 7 days and then divided into a control group and a chronic restraint stress group according to body weight,using a randomized numerical table method.The mice were subjected to restraint stress for 3 hours per day for 14 days to establish an intestinal injury model.The model was evaluated by observing body weight,pathological changes in intestinal histomorphology,expression of tight junction proteins,apoptosis of intestinal epithelial cells,and mRNA expression levels of inflammatory cytokines.Results After 14 days of chronic restraint stress,model mice showed weight loss,shortened duodenal villus height,abnormal crypt structure,a decreased villus/crypt ratio,colonic mucosal inflammatory cell infiltration,and irregular crypt structure.Protein immunoblotting,immunohistochemistry,and immunofluorescence staining showed that the expression levels of the duodenal and colonic tight junction proteins Occludin and Claudin-1 were significantly decreased in mice after chronic restraint stress(P＜0.05),while expression levels of the apoptotic protein cleaved-caspase-3 in intestinal epithelial cells were significantly increased(P＜0.05).Regarding the mRNA expression levels of intestinal inflammatory factors and chemokines,chronic restraint stress for 14 days significantly increased the gene expression levels of interleukin(IL)-1β,IL-6,monocyte chemoattractant protein-1(MCP-1),tumor necrosis factor-α,and IL-10 in the duodenum of mice(P＜0.05),and significantly increased the gene expression levels ofIL-1β,IL-6,and MCP-1 in the colon(P＜0.001).Conclusions The use of a behavioral restriction device to restrain mice continuously for 14 days led to abnormal intestinal tissue structure,intestinal barrier dysfunction,and intestinal epithelial cell apoptosis,and triggered an intestinal inflammatory response in the stressed mice,indicating successful establishment of a mouse model of intestinal injury by chronic restraint stress.