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Objective To establish a new murine model of experimental autoimmune myositis by immunizing with MYBPC2 protein. Methods The purified Myosin-binding protein C, fast type (MYBPC2) was emulsified with complete Freundˊs adjuvant, then C57BL/6 mice were immunized by multi-point subcutaneous injection (0, 7 days), and intraperitoneal injection of pertussis toxin 2 μg simultaneously. The pathological changes of mice with different immunizing dose at the preconceived time were ex-plored. Mean-while, mice were immunized with 600 μg each time, and the muscle endurance was tested on the 21th day. The expression of major histocompatibility complex (MHC) class-Ⅰ and the surface biomarkers of the inflammatory cells in muscle tissues were observed. Mann-Whitney U test was used for statistical analysis. Results ① With the increase of immunizing dosage, muscle damage and inflammation tended to be more serious. On the 21th and 28th day, muscle lesions were most significant. Muscle fiber degeneration and necrosis and inflammatory cell infiltration could be seen in the experimental group. ② Compared with the control group, muscle endurance of mice in the experimental group decreased significantly [(6.1 ±1.3) min versus (9.2±1.6) min, U=2.00, P=0.017]. The MHC class-Ⅰ on the muscle fiber surface of the experimental group was positive, scattered infiltration of CD4 +, CD8+ T ly-mphocytes and CD68 + macrophages between muscle fibers and around the vascular areas could be observed, and CD20+B lymphocytes mainly distributed in the area around the blood vessels, nevertheless rarely seen between muscle fibers. Conclusion Exper-imental autoimmune myositis models of mice have been successfully induced by immunizing with MYBPC2 in China for the first time, and similar clinical and pathological features of human polymyositis could be observed. This new model can be used for studying the pathogenesis of autoimmune myositis.
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AIM: To investigate the effect of extracellular signal-regulated kinase 1/2 signaling pathway after severe diffuse brain injury (DBI) in rats, and to provide base for treatment. METHODS: Male Sprague-Dawley rats were randomly divided into four groups: control group, traumatic group, low dose of inhibitor U0126 treatment group and high dose of inhibitor U0126 treatment group. DBI rat model was established according to the description of Marmarou's diffused brain injury. At 30 min and 1 h, 6 h, 24 h, 48 h and 72 h after injury, morphological changes were observed under light and electronic microscopes. The ERK1/2 phosphorylation and c-Fos were measured by Western blotting. Apoptosis was measured with TUNEL method. Learning and memory function were performed with Morris water maze from 3 days to 7 days after injury. RESULTS: After trauma, some neurons displayed histopathologic changes of necrosis and apoptosis, axon myelin sheath internalization and disconnection. ERK1/2 phosphorylation protein was apparently increased at 30 min after injury, approached peak at 6 h and continued to 24 h. c-fos protein was markedly increased at 30 min after injury, approached peak at 6 h and returned to bottom at 24 h. The number of apoptotic nerve cells increased at 6 h after and approached peak at 72 h. Latencies of searching safety island prolonged. Rats treated with U0126 had reduction in ERK1/2 activity, c-Fos protein, neuronal apoptosis and searching safety island latencies. CONCLUSION: The activated ERK1/2 signaling pathway plays an important role in processing of nerve cell apoptosis after severe DBI.