This paper reviews and analyzes the modifications of silicone rubber, containing nanometer material tilling, plasma surface modification, surface grafting, mixture with bioactive substrates and bionic coating. At last, the author shows the prospect for the future development of silicone rubber modification.
Equipment and Supplies ; Humans ; Silicone Elastomers ; chemistry

Objective To study the feasibility and safety of limb remote ischemic preconditioning (RIPC) in infants and explore the protective effect on myecardium ischemia reperfusion injury for infants undergoing cardiac operation under cardiopulmonary bypass. Methods 60 infants weight less than 7 kilograms with ventricular septal defect were enrolled into the study. 30 of them (RIPC group) were ischemic preconditioned two times (24 hours and 1 hour preoperatively) by three cycles of iscbemia (5 minutes for each) and reperfusion on the left upper arm using a blood pressure cuff. Serum lactate dehydrogenase (LDH), creatine kinase (CK) and its isoenzyme (CK-MB), and tro-ponin I (TnI) ; malondialdehyde (MDA) and superoxide dismutase (SOD) was preoperatively detected. The expression of heat shock pro-tein 70 (HSP 70) in cardiomyocytes was determined by western blot analysis. The surgical outcome including limb movement and sensory function was also recorded. Results No limb disability or sensory disturbance or no other surgical complications was found in all infants. LDH, CK, TnI at the beginning of operation in RIPC group was higher than those in control group. After operation, leakage of heart enzymes were attenuated in RIPC group, and the serum concentration of enzymes were lower than those in the control group. The RIPC group had low coronary sinus venous concentration of MDA but high SOD. The expression of HSP70 was upregulated in cardiomyocytes of RIPC group. Conclusion The limb RIPC can be done easily and safety in infants, and BIPC can reduce the leakage of myocardial enzymes and upregu-late the expression of HSP, which possess protective effect on myocardial IRI.

This paper reviews and analyzes the modifications of silicone rubber, containing nanometer material fil ing, plasma surface modification, surface grafting, mixture with bioactive substrates and bionic coating. At last, the author shows the prospect for the future development of silicone rubber modification.

Objective:To analyze the risk factors for patellar clunk syndrome after total knee arthroplasty (TKA) without patellar surface replacement.Methods:Retrospectively analyzed were a total of 222 patients who had undergone TKA without patellar surface replacement at Department of Joint Surgery, The Second Hospital of Shanxi Medical University from June 2020 to June 2021. There were 43 males and 179 females, and 38 cases of rheumatoid arthritis and 184 cases of arthritis. They were divided into a patellar clunk syndrome group ( n = 56) and a non-patellar clunk syndrome group ( n = 166) according to the occurrence of patellar clunk after TKA. The incidence of early patellar clunk syndrome after TKA was 25.2% (56/222). The patient gender, arthritis type, prosthesis type, postoperative range of knee motion, postoperative patellar thickness, Insall-Salvati index, postoperative joint line height, lower extremity muscle strength, and the distance from the tibial plateau to the patellar tendon were recorded. The risk factors for patellar clunk syndrome were determined by univariate analysis and logistic analysis. Results:The univariate analysis showed significant differences between the 2 groups in prosthesis type, postoperative joint line height, postoperative lower extremity muscle strength, and the distance from the tibial plateau to the patellar tendon ( P < 0.05). The logistic analysis showed that the posterior cruciate substituting (PS) prosthesis was an independent risk factor compared with the cruciate-retaining (CR) prosthesis ( OR = 2.791, 95% CI: 1.411 to 5.521, P = 0.003), and the increased lower extremity muscle strength was an independent protective factor ( OR = 0.295, 95% CI: 0.148 to 0.587, P = 0.001). Conclusions:The incidence of patellar clunk syndrome is relatively high. The PS prosthesis may be an independent risk factor relative to the CR prosthesis. As the increased lower extremity muscle strength may be an independent protective factor, the recovery and strengthening of the muscle strength after TKA require more attention.

Objective To investigate the effects and related mechanism of 5-aza-2'-deoxycytidine (Aza) on endothelial function in Hyperhomocysteinemia rats.Methods Adult male SD rats were divided into 3 groups (n =7 each):control group,hyperhomocysteinemia (HHcy) group and Aza group according to the random number table.Control group rats were fed with normal diet.HHcy group rats were fed with diet adding 3％ L-methionine.Aza group rats were fed with diet adding 3％ L-methionine and Aza (0.5 mg/kg) injection for consecutive three days per week for 8 weeks.After 8 weeks,content of rat plasma homocysteine (Hcy) was detected by enzyme linked immunosorbent assay (ELISA).The rat mesenteric artery endothelium-dependent diastolic function was detected.The nitric oxide synthase (eNOS) activity and asymmetric dimethyl fine ammonia acid (ADMA) content were detected by ELISA,and the content of nitric oxide was detected by nitrate reductase method in the mesenteric arteries.The mRNA expression of DNA methyl transferase 1 (DNMT1) and dimethyl arginine acid dimethylamine hydrolase 2 (DDAH2) in the mesenteric arteries were detected by real-time fluorescence quantitative PCR,and the protein expressions of DNMT1 and DDAH2 in the mesenteric arteries were detected by Western blot.The DDAH2 promoter methylation level in the mesenteric arteries was detected by nested methylation specific PCR.Results (1) The content of plasma Hcy was significantly higher in the HHcy group and Aza group compared to the control group ((29.00 ±0.94) μmol/L and (26.43 ±0.47) μmol/L vs.(10.34 ±0.63) μmol/L,both P ＜ 0.01),which was significantly reduced in the Aza group compared with the HHcy group (P ＜ 0.05).(2) Acetylcholine-mediated relaxation at various concentrations was significantly lower in the HHcy group and the Aza group compared with the control group (both P ＜ 0.05),which was significantly increased in Aza group compared with HHcy group (P ＜ 0.05).SNP-mediated relaxation at various concentrations was similar among the three groups(all P ＞0.05).(3) Compared with the control group,the content of nitric oxide in the HHcy group was significantly decreased ((0.52 ± 0.01) μmol/g vs.(0.42 ± 0.00) μmol/g,P ＜ 0.01),which could be increased by Aza((0.49 ± 0.01) μmol/g,P ＜ 0.05);the eNOS activity in the HHcy group was significantly decreased ((0.74 ± 0.01) U/mg vs.(0.57 ± 0.00) U/mg,P ＜ 0.01),which could be significantly increased by Aza ((0.65 ±0.01) U/mg,P ＜0.01);the content of ADMA in the HHcy group was significantly increased ((0.34 ± 0.01) μmol/g vs.(0.37 ± 0.00) μmol/g,P ＜ 0.05),which could be significantly decreased by Aza ((0.32 ± 0.01) μmo]/g,P ＜ 0.05).(4) Compared with the control group,the relative expression of DDHA2 mRNA in the HHcy group was significantly decreased (0.15 ±0.01 vs.0.12 s0.01,P ＜0.01),which could be significantly increased by Aza (0.13 ± 0.01,P＜ 0.05);the relative expression of DDHA2 protein in the HHcy group was significantly decreased (0.31 ± 0.02 vs.0.24 ± 0.01,P ＜ 0.01),which could be significantly increased by Aza (0.28 ± 0.01,P ＜ 0.01).Compared with the control group,the relative expression of DNMT1 mRNA in the HHcy group was significantly increased (0.23 ± 0.01 vs.0.43 ± 0.01,P ＜ 0.01),which could be significantly decreased by Aza (0.39 ±0.01,P ＜0.05);the relative expression of DNMT1 protein in the HHcy group was significantly increased (0.35 ±0.01 vs.0.50 ±0.01,P ＜0.01),which could be significantly decreased by Aza (0.47 ± 0.01,P ＜ 0.05).(5) Compared with the control group,the methylated/non methylated ratio of DDHA2 promoter in the HHcy group was significantly increased (1.04 ± 0.03 vs.1.26 ± 0.03,P ＜ 0.01),which could be significantly decreased by Aza (0.80 ± 0.03,P ＜ 0.01).Conclusion Aza can inhibit the activity of DNMT1,reduce DDAH2 promoter methylation level,increase the expression of DDAH2,decrease the content of ADMA,increase eNOS activity and content of nitric oxide,thus lead to the improvement of endothelial dysfunction in mesenteric artery of Hyperhomocysteinemia rats.

Aiming at the non-stationarity and temporal characteristics of variable-length electrocardiogram(ECG)signals,an arrhythmia identification algorithm is proposed based on continuous wavelet transform and higher-order statistics.Considering the varying number of data points for each sample in variable-length ECG signals,the RR interval interpolation method is employed for data preprocessing,and the signal is decomposed into different time-frequency components using continuous wavelet transform,which enables the network to better extract both temporal and frequency features from the ECG signals.Regarding the issue of insufficient utilization of temporal information,a temporal mining module is introduced based on higher-order statistics and long short-term memory network to capture and learn long-term dependencies in the ECG signals,thereby facilitating the identification and understanding of specific arrhythmia categories.Extensive experiments conducted on the publicly available MIT-BIH ECG database validate the effectiveness and superiority of the proposed method.