BACKGROUND:With the development of modern orthodontics, to invent an efficient appliance is the focus in
recent studies. Transmission straight wire appliance was born on this background. This appliance can accelerate occlusion and shorten treatment duration. The relationship between distal width and angulation of gable bends of main arch wire needs to study in depth.
OBJECTIVE:To establish three-dimensional finite element model of transmission straight wire appliance with better biological and mechanical similarity, and to obtain the relationship between distal width and angulation of gable bend of main arch wire.
METHODS:By using scanning of spiral CT with 64 rows, the sectional image data in DICOM format of maxil ary dentition and maxil ae of the volunteers (Class Ⅱ, division 1) were obtained. With the help of Ansys workbench 13.0, Mimics 10.01, Unigraphics NX and Geomagic Studio 8.0 softwares, the three-dimensional finite element model including transmission straight wire appliance, bend, Australian Orthodontic Wire, maxil ae, maxil ary tooth and periodontal ligament was established in Windows XP Service Pack 3 system.
RESULTS AND CONCLUSION:A three-dimensional finite element model of transmission straight wire appliance was established, which consisted of 250 929 elements and 657 766 nodes. Furthermore, three-dimensional finite element model had higher geometric similarity and mechanical similarity, as wel as the advantages of adding or subtracting components according to the requirement of the research. The model was conductive to analyze the mechanical system of transmission straight wire appliance and guide the clinical application and appliance modification.

Objective To identify inflammation-related genes in atrial fibrillation(AF)and explore the possible role and mechanism of these genes and infiltrating immune cells in the development of AF.Methods A series of bioinformatics analysis combined with machine learning algorithms to identify biomarkers of AF,the receiver operating characteristic(ROC)curves were used to verify the prediction and diagnostic value of key genes,and Spearman correlation analysis was used to clarify the correlation between key genes and infiltrating immune cells.Results 593 differential genes(| log2(fold change,FC)|>1,P<0.05),7 immune cell subtypes(P<0.05)were selected,190 immune-related differential genes were obtained,3 biomarkers(IGF1,PTGS 2 and PPARG),and the correlation analysis showed that 3 markers were significantly associated with infiltrating immune cells(P<0.05).Conclusion IGF1,PTGS2 and PPARG are inflammation-related genes of AF,which are speculated to be closely related to the process and pathway of immune cell infiltration.

AIM:To investigate the regulatory role of retinoid X receptor(RXR)in oxidative stress response of rat type Ⅱ alveolar epithelial cells(AECII)induced by hypoxia/reoxygenation(HR).METHODS:The AECII were di-vided into control(C)group,HR group,HR+solvent dimethyl sulfoxide(DMSO)group(HD group),HR+RXR agonist 9-cis-retinoic acid(9-RA)group(RA group),and HR+RXR antagonist HX531 group(HX group).Cell Counting Kit-8(CCK-8)method was used to measure the cell viability.Immunofluorescence staining was used to detect the expression of surfactant protein A(SP-A)and RXRα in AECII.Kits were detected to the levels of superoxide dismutase(SOD)and malondialdehyde(MDA)in cells.Transmission electron microscopy was used to observe the ultrastructural changes of the cells.Western blot was used to detect the protein level of nuclear factor E2-related factor 2(Nrf2).RT-PCR was used to detect the expression level of Nrf2 mRNA.RESULTS:Compared with C group,the cell viability and SOD activity in HR,HD,RA and HX groups were decreased significantly(P<0.05),the MDA content were increased significantly(P<0.05),the Nrf2 mRNA and protein expression levels were decreased significantly(P<0.05 or P<0.01),and the immuno-fluorescence expression of RXRα was significantly increased(P<0.01).Compared with HR and HX groups,the cells in RA group showed significantly increased cell viability(P<0.05),increased SOD activity(P<0.05),decreased MDA con-tent(P<0.05),increased Nrf2 mRNA and protein expression levels(P<0.01),and significantly increased immunofluo-rescence expression of RXRα(P<0.01).CONCLUSION:Hypoxia/reoxygenation can aggravate the oxidative stress re-sponse of rat AECII,and RXR agonist intervention can alleviate HR-induced rat AECII injury by inhibiting oxidative stress.

AIM:To investigate the effects of sodium hydrosulfide(NaHS)on hexokinase 2(HK2)-nucleo-tide-binding oligomerization domain-like receptor protein 3(NLRP3)-gasdermin D(GSDMD)pathway and pyroptosis in-duced by lung ischemia/reperfusion(I/R)in rats.METHODS:Male Sprague-Dawley rats were divided into 6 groups:control group,control+NaHS group,I/R group,low-dose NaHS+I/R(L+I/R)group,medium-dose NaHS+I/R(M+I/R)group,and high-dose NaHS+I/R(H+I/R)group,with 6 rats in each group.The NaHS was administered via intraperi-toneal injection at 1.5 mL,30 min before modeling.The left lung tissues were collected 30 min after ischemia and 1 h af-ter reperfusion,and the wet/dry weight ratio and total lung water content were recorded.Hematoxylin-eosin(HE)staining was used to examine lung tissue morphological changes.The levels of malondialdehyde(MDA),myeloperoxidase(MPO)and lactate in lung tissues were measured with test kits.ELISA was employed to determine the levels of interleukin-1β(IL-1β)and IL-18.The expression of glycolysis-and pyroptosis-related indicators was analyzed by Western blot,qRT-PCR and immunofluorescence staining.RESULTS:Compared with control group,the rats in NaHS group showed no signifi-cant differences in all laboratory tests(P>0.05).The rats in I/R group exhibited significant lung injury,oxidative stress,increased lactate level,and up-regulated glycolysis and pyroptosis(P<0.05 or P<0.01).Compared with I/R group,the indicators in L+I/R group showed a downward trend(P<0.01)or no difference(P>0.05),while those in M+I/R group dis-played a significant reduction(P<0.05 or P<0.01).However,the indexes in H+I/R group exhibited no significant dif-ferences in these tests(all P>0.05).CONCLUSION:A moderate dose(56 μmol·L-1·kg-1)of NaHS mitigated the oc-currence of pyroptosis by inhibiting the HK2-NLRP3-GSDMD pathway,thus contributing to the attenuation of lung I/R in-jury in rats.