| PAMAM dendrimer (polyamidoamine dendrimer) is a polymer with dentritic branching and radial symmetry. It consists of three parts:a central core, an interior dendritic structure (the branches) and an exterior surface (the end group).PAMAM dendrimers can be divided in to the whole (cationic) or half (anionic) generation polymers. The surface of the whole generation is functionalized with primary amino surface groups and the half generation is with carboxylate surface groups. Due to the cationic surface, the whole generation PAMAM could be used for gene delivery for expression in cells or in animals. Therefore, the biosafety of these PAMAMs need to be evaluated.In this dissertation, we determine the cells viability after PAMAM G1to G8and G3.5, G4.5, G5.5and G7.5treatment. We find that treatment of A549cells by cationic PAMAMs, from G3to G8could cause cells death, while the anionic PAMAMs have no effect on cells viability. Furthermore, we find that PAMAM G3causes A549cells death through autophagy, but not through apoptosis. Treating cells with inhibitor of autophagy,3-methyladenine (3MA), or by knockdown the autophagy related gene, beclin, could improve the cells viability treated by PAMAM G3. In the meanwhile, autophagic cell death happens in the PAMAM G4, G5, G6, G7and G8treated A549cells.In the following step, we analyze the signal transduction pathways in the PAMAM G3induced autophagic cell death. We find that PAMAM G3induced A549autophagic cell death through Akt-TSC2-mTOR pathway.Furthermore, we discover that PAMAM G3could induce acute lung injury and cause death in mice, while the autophagy inhibitor3MA could improve the situation. It is indicated that autophagy plays an important role in PAMAM G3induced mice acute lung injury. In March2009, in the United States and Mexico, a new porcine influenza A H1N1virus was identified from specimens of patients with influenza-like symptom. The virus can spread from person to person has been spreading to more than100countries and regions.Main clinical manifestations of human infected with influenza A H1N1virus was acute respiratory infection symptom. And rapid progression in some patients, sudden high fever, severe pneumonia or secondary acute respiratory distress syndrome, pulmonary hemorrhage, respiratory failure and multiple organ injury were observed. Mechanism of acute respiratory infection related injury caused by pathogenic is not clear yet.In this study, we established animal model of Influenza A H1N1virus infection in mice, found that:the activation of NF-κB signaling can induce production of inflammation-related factors (cytokines, chemokines), then the formation of cytokine storm, which plays an important role in the process of acute lung injury in mice after Influenza A H1N1virus infection.By detecting the mortality of mice, the lung wet to dry ratio, lung pathology, the level of the inflammation-related factors (cytokines, chemokines) in broncho-alveolar lavage fluid and phosphorylation of NF-K B and IK B-a in lung mononuclear macrophages as indicators, we compare the virulences of different strains of influenza virus after infection. Influenza A H1N1virus BJ strain on the4-week-old C57BL/6mice was found with a stronger ability of lung injury, in comparison to CA07strain. And the viral load in lung tissue of mice was significantly higher than CA07strain.Infected with influenza A H1N1virus strain BJ, mice given continuous steroid Dexamethasone, which significantly reduced mortality and markedly respited the lung injury.These findings expand our understanding of influenza A H1N1virus induced lung injury and also provide valuable information for the anti-viral research.
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