Objective The athletic performance and physiological indicators of two top seated cross-country skiers during simulated competitions were analyzed,and the characteristics of exercise intensity and pacing strategies in different terrains were explored,so as to provide a scientific basis for physical fitness allocation and speed rhythm optimization of the athletes.Methods Differential global positioning system and Momentum Technology MT-Sports T2 were used to test athlete A and athlete B with class of locomotor winter 10(LW 10),who were the first and second runners-up of Beijing Winter Paralympic mid-distance cross-country ski race.The athletes' real-time gliding speed and heart rate during five consecutive 15 km cross-country skiing time trials were collected,and the time spent on each section,speed and heart rate changes in each course were analyzed.Results The coefficient of variation(CV)of mean heart rate on uphill and flat terrain sections were significantly correlated with total scores.The average gliding speed and average heart rate as a percentage of maximum heart rate(HRmax)of the athletes in three terrains were significantly correlated with total scores.The correlation between the mean time spent on uphill and flat terrain and total performance was stronger than that between the mean time spent on downhill terrain and total scores.Both athletes used a cumulative acceleration speed rhythm.Conclusions Uphill and flat terrain time are critical to race performance.Athletes adopt a progressive pacing strategy,gradually increasing speed in the first half,maintaining stable output in the mid-race,and finishing the last lap at a high-speed.Heart rates are mainly distributed between 70％-90％HRmax,and balancing high-intensity efforts on uphills with recovery on downhills helps optimize energy expenditure.

Malaria is an infectious disease caused by Plasmodium through the bite of female mosquitoes, posing a significant threat to global public health. Since 2000, humans have adopted various measures to prevent and control malaria, but due to the impact of COVID-19, the number of malaria cases has increased rather than decreased, making malaria vaccines one of the focal points for controlling the disease. The Plasmodium that infects humans mainly includes Plasmodium falciparum and Plasmodium vivax. The life cycle of Plasmodium includes the pre-erythrocytic stage, the blood stage, and the mosquito stage. Two vaccines, RTS,S/AS01E, and R21/Matrix-M, which have been pre-qualified by the World Health Organization to target the pre-erythrocytic proteins of Plasmodium falciparum. The clinical trial data show reduction in malaria mortality rates among children, and mass vaccination is currently underway in Africa. However, no malaria vaccines targeting other stages or antigens have yet entered phase III clinical trials. This article describes the hazards and prevention of malaria, summarizes malaria vaccines designed in recent years for the three stages of the Plasmodium life cycle: the pre-erythrocytic stage, the blood stage, and the mosquito stage, and demonstrates the challenges and ideas in the field of malaria vaccine research and development, aiming to provide some reference for the development of novel malaria vaccines.

This study reviews recent publications on the biomechanical causes and treatment of flat foot,through searching PubMed,Web of Science,CNKI,Wanfang and other databases.The reasons for the formation of flat foot include congenital factors and acquired factors,while the treatment methods mainly include orthopedic insoles,physical therapy,surgical therapy and exercise therapy.These methods,to a certain extent,can correct foot structural abnormalities,optimize biomechanical properties and improve foot stability and range of motion.For future research,the advanced imaging and simulation technology will be used for accurate assessment,the application of novel materials and non-surgical therapies will relieve long-term symptoms,genetic researches will promote the development of early diagnosis and personalized treatment,and the use of intelligent orthosis will realize real-time monitoring and dynamic adjustment,to provide more and more effective methods and means for the evaluation,intervention and treatment of flat foot.

Objective The athletic performance and physiological indicators of two top seated cross-country skiers during simulated competitions were analyzed,and the characteristics of exercise intensity and pacing strategies in different terrains were explored,so as to provide a scientific basis for physical fitness allocation and speed rhythm optimization of the athletes.Methods Differential global positioning system and Momentum Technology MT-Sports T2 were used to test athlete A and athlete B with class of locomotor winter 10(LW 10),who were the first and second runners-up of Beijing Winter Paralympic mid-distance cross-country ski race.The athletes' real-time gliding speed and heart rate during five consecutive 15 km cross-country skiing time trials were collected,and the time spent on each section,speed and heart rate changes in each course were analyzed.Results The coefficient of variation(CV)of mean heart rate on uphill and flat terrain sections were significantly correlated with total scores.The average gliding speed and average heart rate as a percentage of maximum heart rate(HRmax)of the athletes in three terrains were significantly correlated with total scores.The correlation between the mean time spent on uphill and flat terrain and total performance was stronger than that between the mean time spent on downhill terrain and total scores.Both athletes used a cumulative acceleration speed rhythm.Conclusions Uphill and flat terrain time are critical to race performance.Athletes adopt a progressive pacing strategy,gradually increasing speed in the first half,maintaining stable output in the mid-race,and finishing the last lap at a high-speed.Heart rates are mainly distributed between 70％-90％HRmax,and balancing high-intensity efforts on uphills with recovery on downhills helps optimize energy expenditure.

This study reviews recent publications on the biomechanical causes and treatment of flat foot,through searching PubMed,Web of Science,CNKI,Wanfang and other databases.The reasons for the formation of flat foot include congenital factors and acquired factors,while the treatment methods mainly include orthopedic insoles,physical therapy,surgical therapy and exercise therapy.These methods,to a certain extent,can correct foot structural abnormalities,optimize biomechanical properties and improve foot stability and range of motion.For future research,the advanced imaging and simulation technology will be used for accurate assessment,the application of novel materials and non-surgical therapies will relieve long-term symptoms,genetic researches will promote the development of early diagnosis and personalized treatment,and the use of intelligent orthosis will realize real-time monitoring and dynamic adjustment,to provide more and more effective methods and means for the evaluation,intervention and treatment of flat foot.

Objective To measure the anatomical parameters of the first maxillary molars in children of different age groups and evaluate the age-related changes in dental crowns.Methods A retrospective analysis was conduc-ted on cone beam computed tomography(CBCT)images of 4-8-year-old children.NNT software was used to ana-lyze multiple important indicators of maxillary first molar.Results A total of 308 first maxillary molars,including 154 pediatric patients,were evaluated in this study.The thickness of the pulp apex H1(left,P=0.01;right,P=0.02)and the thickness of the pulp chamber floor H3(left and right P＜0.01)were positively correlated with age,while the height of the pulp cavity H2(left and right P＜0.01)and the height of the palate tip D1(left P=0.003,right P=0.002)showed a negative correlation with age.There was no significant correlation between the height of the buccal tip and age(P＞0.05).There were significant differences in H1 and H3 between the 4-year-old and 5-year-old age groups between the 8-year-old age group(P＜0.05),as well as significant differences in H2 and D1 between the 4-year-old and 5-year-old between the 6-year-old,7-year-old and 8-year-old age groups(P＜0.05).Conclusion The age-related changes in the crowns of the first maxillary molars are important references for the clinical treatment,and can be accurately measured through CBCT data.

Objective To evaluate and compare the treatment efficacy between concentrated growth factor(CGF)and blood clots(BC)as scaffolds in regenerative endodontic procedures(REPs).Methods Twenty young permanent teeth from 18 healthy children with pulp necrosis or periapical periodontitis were randomly divided into CGF group and BC group.In the CGF group(n=10),after ap-ical bleeding,CGF was inserted into the root canal as a stent.In the BC group(n=10),by stimulating apical bleeding,blood entered the root canal and produced blood clots as scaffolds.Clinical examination and apical X-ray shooting were conducted for each follow-up visit.Cone beam computed tomographic(CBCT)images were acquired preoperatively and at the 24-month recall.The increase of root length,root wall thickness,and newly-formed calcified tissue were calculated.Results The root length increased by(1.68±0.90)mm in the CGF group and(2.36±1.34)mm in the BC group.Root wall thickness increased by(0.44±0.34)mm in the CGF group and(0.50±0.31)mm in the BC group.There was no statistically significant difference in root lengthening and root wall thickening between two groups(P＞0.05).The amount of newly formed calcified tissue in the CGF group((22.13±19.12)mm3)was significantly less than that in the BC group((42.97±22.69)mm3)(P＜0.05).According to the goals for success outlined by American Association of Endodontists(AAE),90%(9/10)of the CGF cases and100%(10/10)of the BC cases achieved the primary and secondary goals(P＞0.05).40%of the CGF cases(4/10)and 60%of the BC cases(6/10)achieved the tertiary goal(P＞0.05).Conclusion CGF is found to be use-ful as a scaffold for REPs,but the success rate is slightly lower than that of BC group and the difference is not statistically significant.

Objective As a signaling molecule,NO regulates key physiological processes and is closely related to periodontitis.To investigate the effect of flavonoid NO donor composite nanoparticles(G10@HAP/MSN@ZnO@COS)on osteogenic differentiation of periodontal ligament stem cells(PDLSCs)by regulating macrophage polarization.Methods The novel NO donor drug G10 was loaded on hydroxyapatite/mesoporous silicanant particles(HAP/MSN),filled with zinc oxide(ZnO),and then coated with chitosan(COS)to prepare composite nanoparticles(G10@HAP/MSN@ZnO@COS).The best concentration of G10@HAP/MSN@ZnO@COS was screened to promote cell proliferation by CCK-8 cell experiment.After the mouse mononuclear macrophages were stimulated by lipopo-lysaccharide,the mice were divided into four groups:Control group,G10 group,HAP/MSN@ZnO@COS group and G10@HAP/MSN@ZnO@COS group.Each group was cultured with fresh medium,5 μg/mL G10,5 μg/mL HAP/MSN@ZnO@COS and 5 μg/mL G10@HAP/MSN@ZnO@COS for 72 h respectively.ELISA and RT-qPCR were used to detect the expression of cytokines(TNF-α,IL-6,IL-1β,iNOS,IL-10)and mRNA expression in each group,and the phenotypic changes of M1/M2 were evaluated.The supernatant of each culture medium was used as conditioned medium to culture PDLSCs,and the osteogenic ability and cell miner-alization were evaluated by alkaline phosphatase activity test and alizarin red staining.Results CCK-8 experiment showed that G10@HAP/MSN@ZnO@COS of 5 μg/mL could significantly promote the proliferation of PDLSCs.The results of ELISA showed that compared with Control group,the expression of M1 type marker IL-1β,IL-6,TNF-α and iNOS in G10@HAP/MSN@ZnO@COS group was significantly decreased(P＜0.000 1),while the expression of M2 type marker IL-10 was significantly increased(P＜0.000 1).The results of RT-qPCR were consistent with those of ELISA,which showed that the expression of M1-related genes in G10@HAP/MSN@ZnO@COS group decreased significantly(P＜0.01).The results of alizarin red staining and alkaline phosphatase activity test showed that the number of mineralized nodules and alkaline phosphatase activity in G10@HAP/MSN@ZnO@COS-CM group were significantly higher than those in other groups(P＜0.000 1).Conclusion Composite nanoparticles(G10@HAP/MSN@ZnO@COS)can effectively inhibit the polarization of macrophages to M1 phenotype and promote it to M2 phenotypic polarization.The anti-inflammatory microenvironment regulated by G10@HAP/MSN@ZnO@COS can en-hance the osteogenic differentiation of PDLSCs.

Objective: Investigate osteogenic differentiation of canine periodontal ligament stem cells ( cPDLSCs) via over-expression ephrinB2 in cPDLSCs． Methods : cPDLSCs were isolated from the premolars and molars of Beagle．After transfected with EfnB2-GFP-Bsd and GFP-Bsd empty Vector，cPDLSCs were induced to osteogenic differentiation．Western blot was used to invest the expression of ephrinB2 protein．The effect of osteogenic differentiation of EfnB2-cPDLSCs and Vector-cPDLSCs were analyzed by RT-PCR , CCK-8，Alizarin-red S staining and ALP. Results: There was no significant difference in cell proliferation between EfnB2-cPDLSCs and Vector-cPDLSCs．While EfnB2-cPDLSCs displayed an enhanced ALP activity and more prominent mineralized nodules compared with Vector-cPDLSCs．The odonto-/ osteogenic genes in EfnB2-cPDLSCs were also highly enhanced． Conclusion The results of our study indicated that ephrinB2 gene-transfected cPDLSCs showed enhanced osteogenic differentiation.

Objective: To investigate the effect of Wnt3a on osteogenic differentiation of human dental pulp stem cells (DPSC). Methods: DPSCs were subjected to different concentrations of Wnt3a (0, 5, 20, 50 and 100 μg/L) and at seven days after culture the alkaline phosphatase (ALP) activity was tested. Mineralized nodule formation was examined by alizarin red staining. Osteogenic-related gene expression of bone sialoprotein (BSP), osteocalcin (OCN), collagen type Ⅰ (COL-Ⅰ), Runt-related transcription factor-2 (RUNX2) was examined by quantitative real-time PCR (qPCR). Results: After seven days of induction by DPSC, Wnt3a protein could inhibit the ALP activity (concentration 0: 1.076±0.203, 5 μg/L: 0.828±0.118, 20 μg/L: 0.505±0.044, 50 μg/L: 0.499±0.038, 100 μg/L: 0.483±0.060). The expression of OCN in 5 μg/L Wnt3a group (0.092±0.005) was lower than that in culture medium (0.858±0.190)(P<0.05). Alizarin red staining showed that 5 μg/L Wnt3a had no mineralization induction effect on DPSC. Conclusions Wnt3a could inhibit osteogenic differentiation of dental pulp stem cells.