BACKGROUND:Bone marrow stem cels combined with traditional surgery regimen can significantly improve the therapeutic effects on bone nonunion, which are considered to have an important application value. OBJECTIVE:To explore therapeutic effect of bone marrow mesenchymal stem cels on bone nonunion under micro-damage environment. METHODS:Forty New Zealand white rabbits were selected and randomized into experimental and control groups, 20 rabbits in each group. Bone marrow of the tibia was extracted to isolate and culture bone marrow mesenchymal stem cels. Passage 3 cels with the order of magnitudes of 107 were labeled by superparamagnetic iron oxide nanoparticles. A 15-mm bone defect was made at the middle of the radius of the rabbit forelimb. Bone nonunion appeared at 6 weeks after bone defects. Bone marrow mesenchymal stem cels combined with iliac particles were implanted into the bone defect of rabbits in the experimental group, and only iliac particles were implanted into the bone defect of rabbits in the control group. Within 12 weeks after implantation, the bone nonunion was observed through gross morphology, X-ray observation, and pathological observation. RESULTS AND CONCLUSION:After implantation, a remarkable calus was found in the experimental group, and the bone defect recovered gradualy until it was completely healed; in the control group, there was no calus, and the bone marrow cavity was closed and ful of granulation tissues. In the experimental group, there were actively proliferated cartilage tissues, bone particles were fused, osteoid structures appeared, and osteoblasts proliferated progressively; in the control group, poor cartilage hyperplasia was found, and there were a large amount of dead bone tissues but no fused bone particles and osteoblasts. In the experimental group, X-ray films on the defected radium showed cloudiness-like shadow, the bone marrow cavity was recanalized, and the skeleton was shaped wel; in the control group, few bone particles were absorbed, the bone marrow cavity was partly recanalized, and the injured bone was not healed with osteosclerosis. These findings indicate that under the micro-damage environment, bone marrow mesenchymal stem cels can differentiate into osteoblasts to repair bone defects-induced bone nonunion.

Objective To investigate the inhibition of Eriobotryae Folium from twenty different districts towards phosphodiesterase 4(PDF4) in vitro.Methods The Eriobotryae Folium were extracted with 95％ ethanol reflux and the inhibition rates against PDE4D2 were carried out by liquid scintillation counting method.Results All the samples exhibited inhibitory activities towards PDE4 at 5 mg/L.Among them,nine samples were of the inhibition rate less than 80％,eleven samples were of more than 80％ inhibition and eight samples were of more than 90％ inhibition.Conclusion The Eriobotryae Folium shows significantly different inhibitory activities towards PED4.

Objective To screen a Madin-Darby canine kidney (MDCK) cell line for H5N1 influ-enza virus isolation and to evaluate its safety in vaccine production. Methods MDCK cells were cloned by the method of limiting dilution. Hemagglutination test was used to screen MDCK cells that were suitable for H5N1 influenza virus production. Tests for analyzing the characteristics, extraneous agents, endogenous agents and tumorigenicity of MDCK cells were performed according to Chinese Pharmacopeia Volume Ⅲ. Results A total of 108 MDCK cell lines were obtained and three of them were selected after hemagglutina-tion test. G1 cells were chosen following further screening with tumorigenicity test and receptor abundance analysis. The average number of chromosomes of the MDCK-G1 cells was 78±4. No bacteria, fungi or myco-plasma contamination was detected. In experimental group, each nude mouse was injected with 1×107/ml viable cells to observe their tumorigenicity. Twelve weeks after cell injection, no node was found at injection sites or in gross anatomy. There was no significant difference between the experimental and negative control groups. The result of the tumorigenicity test was negative. No node formation was found after injecting nude mice with cell lysate or cellular DNA collected from equivalent amount of cells. It was indicated that the MDCK-G1 cells were of low-oncogenic potential. Conclusions The MDCK-G1 cell line could be used as a substrate to produce H5N1 influenza virus vaccine.

COVID-19 is caused by a novel coronavirus-severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), which has being spreading around the world, posing a serious threat to human health and lives. Neutralizing antibodies and small molecule inhibitors for virus replication cycle are the main antiviral treatment for novel coronavirus recommended in China. To further promote the rational use of antiviral therapy in clinical practice, the National Center for Infectious Diseases (Beijing Ditan Hospital Capital Medical University and the First Affiliated Hospital, Zhejiang University School of Medicine) invited experts in fields of infectious diseases, respiratory and intensive care to develop an Expert Consensus on Antiviral Therapy of COVID-19 based on the Diagnosis and Treatment Guideline for COVID-19 ( trial version 10) and experiences in the diagnosis and treatment of COVID-19 in China. The consensus is concise, practical and highly operable, hopefully it would improve the understanding of antiviral therapy for clinicians and provide suggestions for standardized medication in treatment of COVID-19.