BACKGROUND: The deficiency of perfect animal femoral head necrosis model limited its further investigation. OBJECTIVE: To verify the feasibility of establishing rabbit femoral head necrosis models using liquid nitrogen rsfdgeration method, and to provide a foundation for subsequent research. METHODS: A total of 20 adult, New Zealand, white rabbits were selected in the study. The round ligament of femur was not cut off and femoral head was not dislocated, and the exposed femoral head were quick frozen using cotton bud carrying liquid nitrogen for successive 25 times, with 10 s per time. The specimens were examined by gross anatomy, X-ray film, MRI and histological observation at day 3, 7 and weeks 2, 4, 6, and 8 after operation. RESULTS AND CONCLUSION: The histolOgical section showed that chondrocyte, osteccyts, and myelold tissues presented necrosis in freezing and periphery at 3days after model preparation, and the repair process appeared at 2weeks after operation. The articular surface of femoral heads appeared collapse at 4 weeks after operation, and these changes became obvious at 6 weeks. The femoral head presented ostecarthdtis-like disorder, with seriously collapsed articular surface at8 weeks, and the contour of femoral head changed in 2 animals. The results demonstrated that without hip dislocation, rabbit femoral head necrosis models can be established successfully using liquid nitrogen refrigeration method. This method is simple, feesible, with high succeed rate, which can be used in subsequent research.

Objective:To evaluate immune response of murine peritoneal macrophage challenging by methicillin-resistant S.aureus(MRSA)after pretreatment with Pam3Csk4(TLR2 agonist).Methods: Murine peritoneal macrophage was pretreated with Pam3Csk4(1 μg/ml).Following pretreatment 12 h later,heat-killed MRSA( HK-MRSA) was added and incubated for another 2 or 6 hours.The protein and mRNA level of TNF-α, IL-6 and IL-1 were determined by ELISA and Q-PCR, respectively.To estimate phagocytosis of macrophage,HK-MRSA/MSSA labeled with FITC( FITC-HK-MRSA/MSSA) were added to well and incubated for 30 min.After washing 5 times with PBS,intracellular FITC-HK-MRSA was detected by flow cytometry.To estimate antimicrobal activity of macrophage,live MRSA and MSSA were added to well and incubated at indication time,the CFU of s.aureus was estimated via a 10-fold serial dilution on agar media.cDNA was further quantitative assessed using primers for mouse FCR-Ⅰ,FCR-Ⅲ,CR-1,CR-3,iNOS and LL37 by Q-PCR .Results: Compared with saline-pretreated cell, the protein and mRNA level of TNF-α, IL-6 and IL-1 were markely reduced, respectively.However, both the phagocytosis and antimicrobal activity to S.aureus were significantly increased in macrophages pretreated with Pam3Csk4.Further study found that the macrophages had higher FCR-Ⅰ,FCR-Ⅲ,CR-1,CR-3,iNOS and LL37 expression at 6 h and 12 h post-stimulation Pam3Csk4.Conclusion: The results suggest that Pam3Csk4 could activate murine antimicrobal activity of peritoneal macrophage challenging by methicillin-resistant Saureus via increasing opsonophagocytosis in depended antibodies, complements manners.The results suggest Pam3Csk4 probably be a novel immunotherapy candidate against MRSA.

BACKGROUND:The authors found that when the bilateral percutaneous vertebral augmentation is used to treat osteoporotic vertebral compression fractures with a total bone cement injection of 4 mL or more,different distribution patterns were usually presented on the X-rays;however,there were few reports addressing the effects of these patterns of bone cement distribution on the biomechanical properties of fractural vertebrae. OBJECTIVE:To further explore the biomechanical effects of different bone cement filling doses and distribution patterns on biomechanics of the fractural vertebrae using the finite element method. METHODS:The L1-L3 finite element models of osteoporosis were established,and the vertebral compression fractures were simulated in L2.Four distribution patterns bilateral partial fusion(FH type),full fusion(FO type),symmetrical separation(SA type),and asymmetric segregation(SN type)were simulated in 4 and 6 mL injections in the osteoporotic vertebral compression fracture models,respectively,and a total of nine sets of models were obtained.These models were solved under the same boundary conditions and compared with the stress and displacement of the L2 fractural vertebra. RESULTS AND CONCLUSION:(1)The maximum stresses of the nine groups of models were concentrated in the L2 fractural area,and the maximum stress and maximum displacement of each filling model were lower than in the osteoporotic vertebral compression fracture model,indicating the effectiveness of bone cement filling in the treatment of osteoporotic vertebral compression fracture.(2)Compared with 4 mL bone cement filling,6 mL bone cement filling could significantly reduce the stress of fractured vertebrae and enhance the strength of fractured vertebrae while improving the stability of fractured vertebrae.(3)In the same state of movement,the FH type stress was the least,followed by the SA type,both of which were close.FO type stress was the largest,especially in the lateral bend,which might be associated with its cluster shape resulting in the concentration of lateral stress.In the aspect of displacement,FH type was the least and FO type was the largest.(4)The results show that increased dose of bone cement injection reduces fractural vertebral stress and improves stability,but increases the risk of leakage.Bilateral symmetrical dispersed bone cement(FH type,SA type)is superior in restoring vertebral strength and stability than full fusion(FO type),asymmetric separated(SN type)bone cement.Therefore,when clinically performing bilateral percutaneous vertebral augmentation treatment of osteoporotic vertebral compression fractures,the bilateral symmetric dispersions of the distribution are first guaranteed;priority is recommended for FH type distribution,for appropriate stress stimulation and best stability.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can cause acute respiratory distress syndrome, hypercoagulability, hypertension, and multiorgan dysfunction. Effective antivirals with safe clinical profile are urgently needed to improve the overall prognosis. In an analysis of a randomly collected cohort of 124 patients with COVID-19, we found that hypercoagulability as indicated by elevated concentrations of D-dimers was associated with disease severity. By virtual screening of a U.S. FDA approved drug library, we identified an anticoagulation agent dipyridamole (DIP) , which suppressed SARS-CoV-2 replication . In a proof-of-concept trial involving 31 patients with COVID-19, DIP supplementation was associated with significantly decreased concentrations of D-dimers ( < 0.05), increased lymphocyte and platelet recovery in the circulation, and markedly improved clinical outcomes in comparison to the control patients. In particular, all 8 of the DIP-treated severely ill patients showed remarkable improvement: 7 patients (87.5%) achieved clinical cure and were discharged from the hospitals while the remaining 1 patient (12.5%) was in clinical remission.