BACKGROUND:Zirconia is considered to be one ofthe promising prosthodontics materials because of its high strength, high hardness, excelent wear resistance and excelent corrosion resistance. However, the development of zirconia is hindered owing to the uncertainty in long-term stability of zirconiaal-ceramic crowns such as the cracking (chipping) of veneering porcelain and deterioration of mechanical properties of zirconia dental crowns under intraoral conditions.
OBJECTIVE:To summarize the preparation of zirconia bioceramic and its application progress in the field of prosthodontics.
METHODS:The properties, crystal structure, preparation and use of zirconia in prosthodontics were reviewed. Reasons that affected the stability of zirconia were also discussed. The future development of zirconia was forecasted.
RESULTS AND CONCLUSION:Preparation of zirconia bioceramics involves the folowing aspects:powder synthesis, biscuit molding, and ceramic sintering.To improvethe istability of zirconia al-ceramic crowns,we optimize the preparation of zirconia powder topromotethe purity, mechanical properties, biological properties and stability. Furthermore, it is necessary to explore the effects of crystal nucleation, growth, second phase and grain size on crystal stability and biomechanical propertiesof thetooth abutment, as wel astoconduct an in-depth theoretical analysis on the effect oftooth abutmentand lattice matching of porcelain crowns on the interface.

Objective To explore the application of continuing nursing model in life of puerperae with preterm infants and evaluate its effects.Methods Based on continuous nursing model of Ahmadi,puerperae's continuing nursing program was constructed.Randomized controlled trail design was used,and totally 110 puerperae in a hospital in Beijing were recruited from August 2016 to March 2017.The experimental group received continuing nursing intervention model,and the control group received routine nursing care.Parenting knowledge and psychological evaluation of the two groups were collected 3 days before discharge,1 month,3 months and 6 months after discharge.Results Ninety-eight puerperae completed the study.In the experimental group,the score of parenting knowledge was higher than that of the control group(P＜0.01),and the total score of mental health assessment and scores of depression and anxiety were lower than those in the control group (P＜0.05).Conclusion Puerperae's continuing nursing program based on the continuous nursing model of Ahmadi improved maternal ability and positive emotion,and promoted quality of life.

Objective To investigate the effect of salt-induced kinase 2 (SIK2) in the G2/M checkpoint in response to ionizing radiation and the possible mechanism.Methods HeLa cells were irradiated with 60Co γ-rays.The cell model of knockdown SIK2 expression was constrcuted by transfecting HeLa cells with a pSicoR-based lentivirus vector of expressing SIK2 shRNA by lipofectamin 2000.Western blot and flow cytometry were performed to measure the changes of SIK2 protein level and cell cycle distribution.The phosphorylated histone protein H3 on Ser 10 was used as a molecular marker of mitotic cells for detecting the function of G2/M checkpoint.Results The expression level of SIK2 protein increased in HeLa cells after 60Co γ-ray irradiation.A cell model of knockdown SIK2 expression was successfully generated by transfecting the specific shRNA against SIK2.Depression of SIK2 significantly increased the cellular sensitivity at 1,2,4,6 Gy post-irradiation (t =-3.445,-2.581,-3.251,-2.553,P ＜0.05),and led cells to release earlier from the G2/M boundary arrest compared to control cells at 5,6 h post-irradiation (t =4.341,6.500,P ＜ 0.05).Western blot analysis indicated that the irradiation-induced phosphorylated CHK2/T68 in SIK2 knock-down cells was earlier than that in control cells.Conclusions salt-induced kinase 2 (SIK2) participates in the regulation of G2/M checkpoint induced by ionizing radiation and affects cellular radiosensitivity.

BACKGROUND:Cobalt chloride (CoCl2) may promote the proliferation of human umbilical cord-derived mesenchymal stem cels (hUC-MSCs) in a time- and concentration-dependent manner, and meanwhile, CoCl2 can regulate the expression of genes and proteins in hUC-MSCs. OBJECTIVE:To explore the effects of CoCl2 induced-hypoxia on the proliferation of hUC-MSCs and gene and protein expressions in hUC-MSCs, thereby establishing an effective method for MSCs culture and amplificationin vitro. METHODS: hUC-MSCs were extracted using tissue explant method. Under hypoxia conditions induced by CoCl2 (0, 100, 150, 200, 250 μmol/L) for different periods (0, 1, 2, 3, 4 days), flow cytometry was used to identify cel surface-associated antigens; cel counting kit-8 was used to detect cel proliferation; RT-PCR was used to determine levels of hypoxia inducible factor-1α, inducible nitric oxide synthase, stromal cel-derived factor-1, interleukin-6, transforming growth factor-β mRNA; western blot assay was used to detect protein expression of hypoxia inducible factor-1α. RESULTS AND CONCLUSION:The cels were positive for CD29, CD73, CD90, CD105, while negative for CD31, CD14, CD34, CD45, CD11b, HLA-DR. Moreover, the antigen expression was not affected by CoCl2 induced-hypoxia. CoCl2 induced-chemical hypoxia could promote the proliferation of hUC-MSCs in a time- and concentration-dependent manner. RT-PCR results showed thatunder hypoxia, hypoxia inducible factor 1α, inducible nitric oxide synthase and stromal cel-derived factor-1 mRNA expressions were significantly up-regulated, but interleukin-6 and transforming growth factor-β mRNA expressions were down-regulated significantly (P < 0.05). Additionaly, the protein expression of hypoxia inducible factor 1α was increased under hypoxia conditions. These findings indicate that CoCl2 induced-hypoxia environment may promote the proliferation of hUC-MSCs and the optimal concentration of CoCl2 is 200μmol/L. However, a higher concentration of CoCl2 (≥ 250μmol/L) inhibits the proliferation of hUC-MSCs, and the mechanism may be related to the increase of hypoxia inducible factor-1α at protein and mRNA levels.

BACKGROUND:The cross-linking reagent is the main unit to support the skeleton of molecularly imprinted polymers, which is closely related to the bio-friendly adaption of polymers. The biocompatible and biodegradable capacities of common crosslinking agents are unclear.
OBJECTIVE:To prepare a novel biodegradable molecularly imprinted polymer and to evaluate the adsorption and biodegradability properties of the polymer.
METHODS:The biodegradable molecularly imprinted polymer was synthesized with the acrylated polyε-caprolactone as the cross-linking reagent under the UV polymerization. The adsorption of the polymer was evaluated by adsorption isotherm, Scatchard analysis and kinetic curves. The biodegradation of the polymer was observed in the simulated physiological environment system in vitro.
RESULTS AND CONCLUSION:Both the molecularly imprinted polymer and non-molecularly imprinted polymer showed an adsorption effect on theophyl ine, the template. But the adsorption amount of the molecularly imprinted polymer was significantly more than that of the non-molecularly imprinted polymer. The drug loading and encapsulation efficiency of the molecularly imprinted polymer were 1.54%and 12.48%, respectively. The degradation rates of molecularly imprinted polymer and poly(ε-caprolactone) diol were 6.60%and 1.33%, respectively, within the observation time in vitro. The obtained molecularly imprinted polymer not only exhibited specific adsorption to certain molecules but also showed good biodegradable properties in the simulated physiological environment system, which is necessary to be a potent drug carrier.

Objective:To explore the independent risk factors and early diagnosis of dermatomyositis (DM) with positive anti-melanoma differentiation associated gene 5 (MDA5) antibody.Methods:A total of 223 DM patients admitted to the Department of Rheumatology and Immunology, Affiliated Hospital of Xuzhou Medical University from January 2012 to June 2021 were retrospectively analyzed, according to whether the anti-MDA5 antibody was positive or not, the patients were divided into anti-MDA5 antibody positive group ( n= 34) and anti-MDA5 antibody negative group ( n=189). The demographic data, clinical manifestations and laboratory test results of the two groups were compared. The risk factors of DM patients with positive anti-MDA5 antibody were analyzed by binary Logistic regression, and the receiver operating characteristic curve (ROC) was drawn to evaluate the predictive value of various risk factors for anti-MDA5 antibody positive DM patients. Results:The incidence of skin ulcer [20.6%(7/34) vs 9.0%(17/189), χ2=4.03, P=0.045], the positive rate of anti-Ro52 antibody [61.8%(21/34) vs 21.2%(40/189), χ2=23.90, P<0.001], the incidence of interstitial lung disease (ILD) [91.2% (31/34) vs 38.6%(73/189), χ2=31.98, P<0.001] and rapidly progressive interstitial lung disease (RP-ILD) [67.6%(23/34) vs 5.3%(10/189), χ2=88.87, P<0.001], the levels of D-dimer [1.87(1.23, 2.56) μg/ml vs 1.15(0.59, 1.29) μg/ml, χ2=4.68, P<0.001] and serum ferritin (SF) [931.65(579.12, 1 160.43) ng/ml vs 507.40(200.40, 588.55) ng/ml, χ2=5.60, P<0.001] in the anti-MDA5 antibody positive group were higher than those in the anti-MDA5 antibody negative group, wherease the creatine kinase (CK) level in the anti-MDA5 anti-body positive group was significantly lower than that in the anti-MDA5 antibody negative group [85.50(61.25, 1 55.00) U/L vs 263.00(66.50, 1 111.14) U/L, χ2=3.08, P=0.002]. Multivariate Logistic regression analysis showed that positive anti-Ro52 antibody [ OR(95% CI)=5.027(1.632, 15.483), P=0.005], increased D-dimer level [ OR(95% CI)=1.665(1.124, 2.466), P=0.011], occurrence of ILD [ OR(95% CI)=10.071(2.061, 49.207), P=0.004] and RP-ILD[ OR(95% CI)=10.91(3.294, 36.134), P<0.001] were independent risk factors for anti-MDA5 antibody positive DM patients. The ROC curve showed that the areas under the curve (95% CI) of anti-Ro52 antibody, D-dimer, ILD and RP-ILD were 0.703(0.615, 0.791), 0.752(0.661, 0.843)], 0.763(0.703, 0.822), 0.812(0.730, 0.893) respectively. The P value of all these parameters were <0.001 and their value in predicting anti-MDA5 antibody positive DM was high. Conclusion:Positive anti-Ro52-Ab, increased D-dimer level, presence of ILD and RP-ILD are independent risk factors for anti-MDA5 antibody positive DM patients, and they have certain early diagnostic value for DM patients with positive anti-MDA5 antibody.

Objective: To evaluate the satisfaction of parents with students eye health services after one year implementation of the "Three-year Action Plan for the Prevention and Control of Myopia in Children and Adolescents in Minhang District (2019-2021)", and to provide a reference for optimizing intervention measures. Methods: A total of 20 176 parents were selected with multi-stage sampling method for the satisfaction evaluate. Results: Health services in appointed medical institutions(6 849, 84.65%), providing feedback on the vision screening(16 915, 83.84%) and procedures in appointed medical institutions(6 704, 82.91%) were the top three terms for parents satisfaction with children and adolescents eye health services, respectively. While the eye behavior and eye environment intervention(8 467, 42.01%), parents informing(7 850, 38.91%) and regular follow-up management(7 222, 33.67%) were the top three that were suggested to improvement. Comparative analysis showed that the school period and the history of previous diagnosis of eye diseases had an impact on the satisfaction of children and adolescents eye health services and the demand for improvement significantly (P<0.05). Conclusion After one year of intervention, parents are generally satisfied with the eye health services for students. At the same time, students with different characteristics parents focused on difference needs for health services. It urges more refined and personalized eye health services should be provided.

Objective: To determine the influencing factors of electronic screen time of urban preschoolers before and after the COVID-19 outbreak, so as to provide a scientific basis for the control of digital screen use and early prevention of myopia among preschoolers. Methods: Using multi stage cluster random sampling method, a cross sectional survey of 8 244 kindergarten students in a district of Shanghai was implemented, through parent questionnaire collecting the time child spent on various electronic screens before and after the COVID-19 outbreak, estimated the weighting screen time, and emphatically analyzed the relationship between family electronic screen supervision behavior and preschoolers weighting screen time. Results: The proportion of daily over use time on average of mobile phones, computers and TV/projection screens among the surveyed preschool children during COVID-19 was 30.52%, 51.40% and 56.82%, respectively. On school days before the epidemic, the proportion was 21.94%, 41.80% and 47.51% respectively. After controlling for primary covariates, parents frequent control of children s electronic screen use, parents guidance for electronic screen use were significantly associated with lower weighted screen refractive time ( OR =0.60-0.77, P < 0.05 ). The use of electronic screen when parents accompanied their children, the use of electronic screen time by parents but not strictly implemented were significantly associated with higher weighted screen refractive time and increased screen refractive time ( OR =1.18-1.80, P <0.05). Conclusion Urban preschoolers electronic screen time was high during and before COVID-19. In the control measures of preschool children s electronic screen time, attention should be paid to the management of electronic screen use within the family and parents role model.

Objective: To development teacher health literacy on students visual protection questionnaire for kindergarten, primary and middle schools, and to provide a basis for quantitative assessment of visual protection health literacy of school teachers. Methods: Based on official documents related to prevention and control of myopia as well as the integrated definition of health literacy of WHO Europe, the framework for technical evaluation was established. Totally 24 multi disciplinary experts in related fields conducted two round Delphi expert consultation. Evaluation items, questions and corresponding weights were determined based on experts opinions and scores. Results: In two rounds of Delphi consultation, the response rates were 83.3% and 79.2% respectively, and the authority coefficient was 0.91. The final questionnaire was composed by dimensions of core knowledge of myopia, daily instruction, guidance for myopic behaviors, promotion of outdoor activities, and creation of teaching light environment, including 30 and 23 items for middle and primary school teachers and kindergarten teachers respectively. The coefficient of variation ( CV ) of the five dimensions ranged from 0.07 to 0.15, and that of each question ranged from 0.08 to 0.29. Expert opinions were accordant and credible. Conclusion A reliable questionnaire of teacher health literacy on students visual protection health literacy for school teachers is established, which can be used as the entry point and effectiveness evaluation basis for the school based intervention of myopia.

Objective: The current situation and associated factors of primary and middle school students screen time and related eye hygiene in different periods before and after COVID-19 were investigated, so as to provide a scientific basis for taking targeted measures of preventing and controlling myopia among those students. Methods: A total of 11 402 students were selected from 24 primary schools, 18 junior high schools and 16 high schools by multi stage stratified cluster sampling method. And a questionnaire survey was conducted among students and their parents to understand students screen time and screen hygiene behaviors and related factors in different periods before and after the outbreak of COVID-19. Results: The rate of screen overuse was 7.26%, 9.12% and 35.30% during school days, weekends and home study, respectively. The overuse rate of mobile phones and tablets at home increases with the increase of school stage. Totally 16.30% of students use mobile phones for online learning. The screen overuse rate of those who have not been diagnosed with myopia was lower than that of those who have been diagnosed during home study( OR=0.77, P <0.05). The higher the parents educational level was, the lower the screen overuse rate of children during the weekends became( P <0.05). In any period, the high proportion of screens used in homework and poor home screen eye environment increased the risk of screen overuse and poor eye hygiene ( P <0.05). Parental good behavior was conducive to reducing the risk( OR= 0.65-0.97, P <0.05). When the family had regulation on the screen use time, the implementation of laxity would increase the risk of screen overuse ( OR=1.18-2.48, P <0.05). Conclusion The screen overuse rate of urban primary and middle school students during home study is high, and a certain proportion of students still use mobile phones for online learning. The proportion of screens used in homework, home screen eye environment and screen use management are related to screens overuse. More attention should be paid to those with myopia and low educational level of parents.