Development of a BLI assay-based method for detecting LptA/LptC interaction / 生物工程学报

In Gram-negative bacteria, lipopolysaccharide transport (Lpt) protein LptA and LptC form a complex to transport LPS from the inner membrane (IM) to the outer membrane (OM). Blocking the interaction between LptA and LptC will lead to the defect of OM and cell death. Therefore, Lpt protein interaction could be used as a target to screen new drugs for killing Gram-negative bacteria. Here we used biolayer interferometry (BLI) assay to detect the interaction between LptA and LptC, with the aim to develop a method for screening the LptA/LptC interaction blockers in vitro. Firstly, LptC and LptA with or without signal peptide (LptAfull or LptAno signal) were expressed in E. coli BL21(DE3). The purified proteins were then labeled with biotin and the super streptavidin (SSA) biosensor was blocked with diluent. The biotin labeled protein sample was mixed with the sensor, and then the binding of the protein with a series of diluted non biotinylated protein was detected. At the same time, non-biotinylated protein was used as a control. The binding of biotinylated protein to a small molecule IMB-881 and the blocking of interaction were also detected by the same method. In the blank control, the biosensor without biotinylated protein was used to detect the serially diluted samples. The signal response constant was calculated by using steady analysis. The results showed that biotinylated LptC had a good binding activity with LptAfull and LptAno signal with KD value 2.9e⁻⁷±7.9e⁻⁸ and 6.0e⁻⁷±2.8e⁻⁸, respectively; biotinylated LptAno signal had a good binding activity with LptC, with a KD value of 9.6e⁻⁷±7.2e⁻⁸. All binding curves showed obvious fast binding and fast dissociation morphology. The small molecule compound IMB-881 can bind to LptA to block the interaction between LptA and LptC, but has no binding activity with LptC. In summary, we developed a method for detecting the LptA/LptC interaction based on the BLI technology, and confirmed that this method can be used to evaluate the blocking activity of small molecule blockers, providing a new approach for the screening of LptA/LptC interaction blockers.

Alveolar bone defect repair using autologous bone marrow mesenchymal stem cells combined with platelet-rich fibrin / 中国组织工程研究

Abstract BACKGROUND: Alveolar bone deficiency wil not meet aesthetic and functional requirements for dental implants. OBJECTIVE:To observe the repair effect of passage 3 autologous bone marrow mesenchymal stem cels (BMSCs) and platelet-rich fibrin (PRF) on alveolar bone defects in rabbits. METHODS:Twenty-seven New Zealand rabbits were randomly divided into BMSCs/PRF group, PRF group and model group (n=9 per group). The left mandible incisors were extracted in al the rabbits under general anesthesia. BMSCs/PRF group was immediately implanted BMSCs/PRF composite into the alveolar socket, PRF group only implanted PRF, and model group implanted nothing. RESULTS AND CONCLUSION: In the model group, the alveolar crest and alveolar mucosa become sunken notably and narrowed. In the BMSCs/PRF and PRF groups, the thickness of alveolar bone wal, alveolar bone width, alveolar bone height difference, and bone mineral density were al increased, especialy in the former group. In addition, the trabecular arrangement was better in the BMSCs/PRF groups than the model and PRF group. Our findings indicate that alveolar socket filing with composite of BMSCs and PRF can achieve preservation of alveolar bone width and height after tooth extraction in rabbits.

The animal models of H5N1 avian influenza virus / 基础医学与临床

H5N1 subtype of avian influenza virus (AIV) has been prevailing in many countries over the world, which has threaten human health. The establishment of AIV animal models may provide a tool for the study on the infection, mutation of avian influenza virus and pathogenesis of the disease. The pathogenicity of H5N1 to mammalian such as cynomolgus macaques, ferrets, mice, rats, gerbils, cats were summarized in current review, which may provide meaningful help for the establishment and study on ideal experiment animal models.