BACKGROUND:The elastic modulus of traditional bone implants is large and does not match the elastic modulus of human bone,which will cause a stress shielding effect and lead to bone resorption.The trabecular scaffold of the triply periodic minimal surface with radial gradient has elastic modulus matching with human cancellous bone,and its yield strength is greater than that of human cortical bone,which provides a new choice for the design of bone scaffold. OBJECTIVE:Triply periodic minimal surface structure with radial gradient was constructed by the implicit surface method.The sample was manufactured by laser selective melting technology,and the quasi-static compression test was carried out to obtain trabecular scaffolds with mechanical properties matching human bones. METHODS:Four types of the trabecular scaffolds of the triply periodic minimal surface with a radial gradient of G,I,P and D were established by the implicit surface method.Samples were manufactured by laser selective melting technology.We observed the surface morphology of the molded sample,evaluated the molding quality,conducted a quasi-static compression test,and evaluated the mechanical properties of the samples. RESULTS AND CONCLUSION:The quasi-static compression test results showed that compared with the four triply periodic minimal surface scaffolds,the platform stress of the G scaffold had less fluctuation and no failure or fracture,indicating that the G scaffold had the best plasticity.The mechanical properties of the G scaffolds with 45%,55%and 65%porosities were analyzed.It was found that the elastic modulus of G scaffolds with 55%porosity was within the range of elastic modulus of human cancellous bone(0.022-3.7 GPa),and the yield strength was close to the maximum yield strength of human cortical bone(187.7-222.3 MPa).In conclusion,G triply periodic minimal surface scaffold with 55%porosity can reduce the stress shielding effect,bear a higher body load,improve the stability of the implant,and prolong the service life of the implant.

BACKGROUND:Vertebral compression fracture is a common disease in the current orthopedic field.However,the occurrence of re-fracture in neighboring vertebrae after surgery is a problem that cannot be ignored,which has a serious impact on the normal life of patients. OBJECTIVE:The aim of this study is to establish four postoperative models with different recovery heights using computed tomography images.By using finite element analysis,we derived the stresses on the neighboring vertebrae at different recovery heights and further explored the importance of postoperative recovery of the height of the injured vertebrae. METHODS:A finite element model of the thoracolumbar spine(T11-L3)was established and validated,on the basis of which four postoperative finite element models of L1 with different recovery heights of 100%,80%,60%,and 40%were constructed,in which the cement capacity varied with the recovery height.The specific models are as follows:Model 1 was the postoperative model with normal recovery height,and the cement capacity was 8.3 mL.Model 2 was the postoperative model in which 20%of the anterior height of the L1 was removed and the posterior convexity angle became 10.41°,and the cement capacity was 6.9 mL.Model 3 was the postoperative model in which 40%of the anterior height of the L1 was removed and the posterior convexity angle became 20.17°,and the cement capacity was 4.7 mL.Model 4 was a postoperative model with 60%of the L1 anterior height removed and the posterior convexity angle changed to 28.85°,with a cement capacity of 3.6 mL.For evaluation of the postoperative model,we applied a moment of 7 Nm and an axial force of 500 N.The followings were recorded and analyzed:peak stresses in the L2 upper endplate and T12 lower endplate;peak stresses in the L2 and T12 cancellous bone. RESULTS AND CONCLUSION:(1)The highest peak stresses for each condition of the L2 upper endplate,T12 lower endplate,L2 cancellous bone,and T12 cancellous bone occurred in Model 1 and Model 4.In particular,the T12 lower endplate,except for the posterior extension condition,the anterior flexion,left and right lateral bending,and left and right rotation conditions all reached their highest peak stresses in Model 4,with stresses of 50.3,33.1,44.9,34.3,and 31.9 MPa.(2)Based on the peak stresses in the adjacent vertebral endplates and cancellous bone,after excluding Model 1 and Model 4,the minimum peak stresses for most of the conditions appeared in the Model 2,and the minimum peak stresses appeared in the Model 2 in 66.6%of the cases,especially in the upper endplates of the L2 and cancellous bone except for the posterior extension condition,the minimum peak stresses all appeared on the Model 2.(3)Therefore,controlling the recovery height at about 100%and 40%of the original height was a dangerous recovery height,which had a greater impact on the neighboring vertebrae.Controlling the recovery height at about 80%of the original height may be a more ideal choice.With a recovery height of about 80%of the original height,the adjacent vertebrae are subjected to less stress,thus reducing the risk of re-fracture of the adjacent vertebrae in the patient.

Objective To identify the key genes differentially expressed in Wilms tumor and analyze their potential impacts on prognosis and immune responses of the patients. Methods High-throughput RNA sequencing was used to identify the differentially expressed mRNAs in clinical samples of Wilms tumor and paired normal tissues, and their biological functions were analyzed using GO, KEGG and GSEA enrichment analyses. The hub genes were identified using STRING database, based on which a prognostic model was constructed using LASSO regression. The mutations of the key hub genes were analyzed and their impacts on immunotherapy efficacy was predicted using the cBioPortal platform. RT-qPCR was used to verify the differential expressions of the key hub genes in Wilms tumor. Results Of the 1612 differentially expressed genes identified in Wilms tumor, 1030 were up-regulated and 582 were down-regulated, involving mainly cell cycle processes and immune responses. Ten hub genes were identified, among which 4 genes (TP53, MED1, CCNB1 and EGF) were closely related to the survival of children with Wilms tumor. A 3-gene prognostic signature was constructed through LASSO regression analysis, and the patients stratified into with high- and low-risk groups based on this signature had significantly different survival outcomes (HR=1.814, log-rank P=0.002). The AUCs of the 3-, 5-and 7-year survival ROC curves of this model were all greater than 0.7. The overall mutations in the key hub genes or the individual mutations in TP53/CCNB1 were strongly correlated with a lower survival rates, and a high TP53 expression was correlated with a poor immunotherapy efficacy. RT-qPCR confirmed that the key hub genes had significant differential expressions in Wilms tumor tissues and cells. Conclusion TP53 gene plays an important role in the Wilms tumor and may potentially serve as a new immunotherapeutic biomarker as well as a therapeutic target.

Objective To identify the key genes differentially expressed in Wilms tumor and analyze their potential impacts on prognosis and immune responses of the patients. Methods High-throughput RNA sequencing was used to identify the differentially expressed mRNAs in clinical samples of Wilms tumor and paired normal tissues, and their biological functions were analyzed using GO, KEGG and GSEA enrichment analyses. The hub genes were identified using STRING database, based on which a prognostic model was constructed using LASSO regression. The mutations of the key hub genes were analyzed and their impacts on immunotherapy efficacy was predicted using the cBioPortal platform. RT-qPCR was used to verify the differential expressions of the key hub genes in Wilms tumor. Results Of the 1612 differentially expressed genes identified in Wilms tumor, 1030 were up-regulated and 582 were down-regulated, involving mainly cell cycle processes and immune responses. Ten hub genes were identified, among which 4 genes (TP53, MED1, CCNB1 and EGF) were closely related to the survival of children with Wilms tumor. A 3-gene prognostic signature was constructed through LASSO regression analysis, and the patients stratified into with high- and low-risk groups based on this signature had significantly different survival outcomes (HR=1.814, log-rank P=0.002). The AUCs of the 3-, 5-and 7-year survival ROC curves of this model were all greater than 0.7. The overall mutations in the key hub genes or the individual mutations in TP53/CCNB1 were strongly correlated with a lower survival rates, and a high TP53 expression was correlated with a poor immunotherapy efficacy. RT-qPCR confirmed that the key hub genes had significant differential expressions in Wilms tumor tissues and cells. Conclusion TP53 gene plays an important role in the Wilms tumor and may potentially serve as a new immunotherapeutic biomarker as well as a therapeutic target.

Objective:To compare and evaluate the difference in maxillary dentition position using an anatomical facebow and jaw movement analyzer.Methods:From March to May 2023, 15 medical interns from Yantai Stomatological Hospital were recruited, including 9 males and 6 females, aged 20-25 years. Digital models and plaster models of maxillary dentition were obtained from the 15 medical interns. The anatomical facebow group (AFB) and jaw movement analyzer group (JMA) were used to transfer the position of the maxillary dentition to the virtual articulator. The virtual occlusal articulator module of exocad denture design software was used to measure the inclination angle of the occlusal plane of the two groups, the distance between the mesio-incisal angle of the left maxillary central incisor and the lateral center point of the lateral condylar sphere of the virtual occlusal articulator, the distance between the mesial buccal cusp of the maxillary first molar and the lateral center point of the lateral condyle sphere of the virtual articulator. The same marks (mesial incisor point of left maxillary central incisor and mesial buccal cusp point of both maxillary first molars) were measured in two groups of maxillary dentition, and the root-mean-square error between 3 points was calculated.Results:The occlusal plane inclination angle in AFB group (9.11°±3.85°) was significantly larger than that in JMA group (4.94°±2.69°) ( t=10.45, P<0.001). There were significant differences between AFB and JMA groups. The distances from the mesial cusp of the left first molar to the lateral center of the left condylar, from the mesial cusp of the left maxillary central incisor to the lateral center of the left condylar[(91.75±3.05), (129.09±4.60) mm]were significantly smaller than those in the JMA group[(95.68±5.45), (132.41±5.64) mm]( t=-4.48, P=0.001; t=-4.21, P=0.001). In both groups of models, the distance of the mesial cusp of the left maxillary central incisor was (8.81±2.56) mm, and the distance between mesial buccal cusp of maxillary left first molar was (7.56±2.49) mm, the distance between mesial buccal cusp of maxillary right first molar was (7.13±2.77) mm; the root mean square error was (7.93± 2.94) mm. Compared with 0, the difference was statistically significant ( t=10.45, P<0.001). Conclusions:There were differences between the two methods (anatomical facebow and the jaw movement analyzer) for transferring the maxillary dentition position to the three-dimensional space position of the virtual articulator.

Objective:To summarize the distributional characteristics of postoperative occurrence of multi-drug resistant organism (MDRO) infections and their risk factors in simultaneous pancreas-kidney transplantation (SPK) recipients and examine the impact of MDRO infections on the survival of SPK recipients.Method:From January 2016 to December 2022, the relevant clinical data were retrospectively reviewed for 218 SPK recipients. The source of donor-recipient specimens and the composition percentage of MDRO pathogens were examined. According to whether or not MDRO infection occurred post-transplantation, they were assigned into two groups of MDRO (98 cases) and non-MDRO (120 cases). The clinical data of two groups of donors and recipients were analyzed. And the risk factors for an onset of MDRO infection were examined by binary Logistic regression. The survival rate of two recipient groups was compared by Kaplan-Meier method.Result:A total of 98/218 recipients (45%) developed MDRO infections. And 46 (46.9%) of sputum and 34 (34.7%) of urine were cultured positively and 49 (50%) pathogens expressed extended spectrum beta-lactamase. There were pneumonia (46 cases, 46.9%), urinary tract infections (34 cases, 34.7%), abdominal infections (16 cases, 16.3%) and bloodstream infections (2 cases, 2.0%). Univariate regression analysis revealed that length of renal failure ( P=0.037), length of hospitalization ( P<0.001), length of antibiotic use ( P<0.001), novel antibiotics ( P=0.014), albumin ( P<0.001) and leukocyte count ( P<0.001) were risk factors for an onset of MDRO infections. The results of multifactorial regression indicated that low albumin ( OR=0.855, 95% CI: 0.790~0.925, P<0.001) and leukopenia ( OR=0.656, 95% CI: 0.550~0.783, P<0.001) were independent risk factors for an onset of MDRO infections. The survival rates of recipients in MDRO group at Year 1/3 post-operation were 92.9% (91/98) and 89.8% (88/98). And the survival rate of recipients in non-MDRO group was 96.7% (116/120) at Year 1/3 post-operation. Inter-group difference was not statistically significant in 1-year survival rate of two recipient groups ( P=0.201); statistically significant inter-group difference in 3-year survival rate between two recipient groups ( P=0.041) . Conclusion:Low albumin and leukopenia are risk factors for MDRO infection. Infection with MDRO has some impact on the survival of recipients.

Objective To investigate the distribution and drug resistance characteristics of pathogens in donors and recipients undergoing simultaneous pancreas-kidney transplantation (SPK). Methods Clinical data of 231 pairs of donors and recipients undergoing SPK were analyzed retrospectively. The pathogens of samples from donors and recipients were identified by VITEK-2 analyzer, and drug sensitivity test was performed by K-B method. The source distribution and composition ratio of pathogens in donor and recipient samples, distribution characteristics of multi-drug resistant organism, infection of recipients and drug resistance characteristics of pathogens were analyzed. Results A total of 395 strains of pathogens were cultured from 1 294 donor samples, and the detection rate was 30.53%. Gram-negative bacteria mainly consisted of klebsiella pneumoniae, Gram-positive bacteria mainly comprised staphylococcus aureus, and fungi primarily included candida albicans, respectively. In total, 2 690 strains of pathogens were cultured from 10 507 recipient samples, and the detection rate was 25.60%. Gram-negative bacteria mainly consisted of pseudomonas maltophilia, Gram-positive bacteria primarily comprised enterococcus faecalis, and fungi mainly included candida albicans, respectively. Among 395 pathogens of donors, 15 strains of methicillin-resistant staphylococcus aureus (MRSA), 16 strains of extended-spectrum β-lactamase (ESBL) positive drug-resistant bacteria, 8 strains of carbapenem-resistant pseudomonas aeruginosa (CR-PA), 21 strains of carbapenem-resistant acinetobacter baumannii (CR-AB), 2 strains of carbapenem-resistant enterobacteriaceae (CRE) and 1 strain of multiple-drug/pan-drug resistant pseudomonas aeruginosa (MDR/PDR-PA) were identified. Among 2 690 strains of recipient pathogens, 73 strains of ESBL positive drug-resistant bacteria, 44 strains of CR-PA, 31 strains of CR-AB and 3 strains of MDR/PDR-PA were detected. One recipient developed donor-derived infection, 69 cases of pneumonia, 52 cases of urinary tract infection, 35 cases of abdominal infection and 2 cases of hematogenous infection were reported within postoperative 1 year. Gram-negative bacteria were resistant to certain antibiotics. Gram-positive bacteria were sensitive to vancomycin. Fungi were sensitive to amphotericin B. Conclusions Gram-negative bacteria are the main pathogens of SPK recipients, which are resistant to certain antibiotics. Empirical use of antibiotics can be delivered before culture results are obtained. Subsequently, sensitive antibiotics should be chosen according to the culture results to improve the survival rate of SPK recipients.

PURPOSE: . The objective of this study was to investigate how internal structures influence the overall and marginal accuracy of full arch preparations fabricated through additive manufacturing in different printing systems. MATERIALS AND METHODS: . A full-arch preparation digital model was set up with three internal designs, including solid, hollow, and grid. These were printed using three different resin printers with nine models in each group. After scanning, each data was imported into the 3D data processing software together with the master cast, aligned and trimmed, and then put into the 3D data analysis software again to compare the overall and marginal deviation whose results are expressed using root mean square values and color maps. To evaluate the trueness of the resin model, the test data and reference data were compared, and the precision was evaluated by comparing the test data sets. Color maps were observed for qualitative analysis. Data were statistically analyzed by one-way analysis of variance and Bonferroni method was used for post hoc comparison (α = .05). RESULTS: . The influence of different internal structures on the accuracy of 3D printed resin models varied significantly (P < .05). Solid and grid models showed better accuracy, while the hollow model exhibited poor accuracy. The color maps show that the resin models have a tendency to shrink inwards. CONCLUSION . The internal structure design influences the accuracy of the 3D printing model, and the effect varies in different printing systems. Irrespective of the kind of printing system, the printing accuracy of hollow model was observed to be worse than those of solid and grid models. [J Adv Prosthodont 2023;15:145-54]

Objective:To summarize the clinical characteristics and risk factors of acute rejection(AR)of transplanted pancreas and kidney after simultaneous pancreas-kidney transplantation(SPK)and explore the effects of AR on the survival of transplanted pancreas, kidney and recipients.Methods:From September 2016 to July 2022, the relevant clinical data were retrospectively reviewed for 218 recipients undergoing SPK.According to whether or not AR occurred after SPK, they were assigned into two groups of AR(n=53)and non-AR(n=165). The relevant clinical data were compared for two groups of donors and recipients and the risk factors of AR analyzed by binary Logistic regression.Kaplan-Meier method was employed for comparing the survival rates of recipients/transplanted pancreas and kidneys in two groups.Results:A total of 53 cases(24.3%)developed ARs of transplanted pancreas(n=31, 14.2%)(5 of 2 ARs), transplanted kidney(n=15, 6.9%)(1 of 2 ARs)and transplanted pancreas & kidney AR(n=11, 5.0%)(2 of 2 ARs). Tacrolimus blood levels in AR and non-AR groups were(5.8±1.2)and(6.3±1.6)μg/L and failed to attain targets in 36(67.9%)and 78(47.3%)cases.During follow-ups, the incidence of pneumonia and urinary tract infections in AR group versus non-AR group were[43.4%(23/53)vs.27.3%(45/165)and 39.6%(21/53)vs.18.8%(31/165)]and the differences were statistically significant( P=0.028 & 0.002). The results of multifactorial regression analysis revealed that sub-optimal blood level of tacrolimus was an independent risk factor for an occurrence of AR in grafts of SPK recipients( OR=2.254, 95% CI: 1.167-4.353, P=0.016). Comparisons of 1/5-year postoperative survival rates between recipients in AR and no-AR group(98.1% vs.93.9% and 92.1% vs.92.4%)indicated that the differences were not statistically significant( P=0.233 & 0.806). Through comparing 1/5-year survival rates of transplanted pancreas in AR and non-AR groups(94.3% vs.100%, 89.4% vs.98.6%), the differences were statistically significant( P=0.003 & 0.004). And 1/5-year survival rates of transplanted kidneys in AR and non-AR groups(92.5% vs.100% and 90.2% vs.100%)were compared and the differences were statistically significant(all P<0.001). Conclusions:The incidence of AR is higher in transplanted pancreas and kidney after SPK.And the incidence of pneumonia and urinary tract infection is higher in AR group than that in non-AR group.Sub-optimal blood level of tacrolimus is an independent risk factor for the occurrence of AR.The 1/5-year survival rates of transplanted pancreas and transplanted kidney are lower in AR group than those in non-AR group.It has some effect on the survival of transplanted pancreas and kidney.

Objective:To explore the features of free uroflow(FF) curve patterns in female patients with detrusor underactivity(DU) and their clinical significance.Methods:Data of 275 adult female patients with lower urinary tract symptoms(LUTS) underwent urodynamic studies(UDS) at urology center of our hospital from June 2014 to June 2016 were analyzed retrospectively. The uroflow curve patterns of patients with DU were classified and analyzed in the context of parameters of FF, cystometry (CM), and pressure-flow study(PFS). The prevalence of each abnormal uroflow curve pattern in DU patients were calculated and compared with those in non-DU patients.Results:No bell-shaped curve was found in 141 patients with DU. The abnormal curve patterns can be divided into 5 types: Type Ⅰ (bell-shaped curve with saw tooth) in 20 cases (14.2%), Type Ⅱ (box-like curve) in 34 cases (24.1%), Type Ⅲ (triangle curve with decreasing slop) in 62 cases(43.9%), Type Ⅳ (triangle curve with increasing slop) in 4 cases (4.3%), Type Ⅴ (tide-wave curve)in 19 cases (13.5%). Maximum flow rate of free uroflow(Q max.FF) of type Ⅰ [(28.4±9.7) ml/s] was significantly greater than that of type Ⅱ, Ⅲ and Ⅴ[(17.0±4.1), (15.8±5.4) and (12.9±6.4) ml/s, P<0.05]. Flow time of free uroflow(FT.FF) of type Ⅲ and Ⅴ [(43.7±17.2) and (50.1±28.9)s] were significantly longer than that of type Ⅰ and Ⅱ [(18.5±7.3)s and (27.2±9.7)s, P<0.05]. Post voided residual > 50ml was noted in 19 cases (30.6%) of type Ⅲ, 7 cases (36.8%) of type Ⅴ, 1 case (2.9%) of type Ⅱ and no one in type Ⅰ and Ⅳ. Abnormal manifestations in cystometry mainly included bladder hypersensitivity, detrusor overactivity, and stress urinary incontinence. Detrusor pressure at Q max (Pdet.Q max) of type Ⅴ [(7.4±5.0) cmH 2O] was significantly lower than that of type Ⅰ, Ⅱ, Ⅲ [(11.8±6.7), (12.0±5.3), (12.1±5.0) cmH 2O, P<0.05]. Among 134 cases of non-DU, there were type Ⅰ curves in 88 cases (65.7%), type Ⅱ curves in 4 cases (2.9%), type Ⅲ curves in 15 cases (11.2%), type Ⅳ curves in 1 cases (0.7%), type Ⅴ curves in 7 cases (5.2%). And normal bell-shaped curves in 19 cases(14.2%). The prevalence of type Ⅱ, Ⅲ and Ⅴ in DU patients was significantly higher than that in the non DU patients ( P<0.05). Conclusions:This study reveals that the characteristics of reduced detrusor contractility and duration, prolonged bladder emptying or incomplete emptying can be reflected in the patterns of free uroflow curve in female patients with DU. The abnormalities of these free uroflow curve patterns, especially type Ⅱ, Ⅲ and Ⅴ will be helpful in preliminarily screening DU in females.