ABSTRACT
Recombinant bacterial vector vaccines have been widely used as carriers for the delivery of protective antigens and nucleic acid vaccines to prevent certain infectious diseases because of their ability to induce mucosal immunity, humoral immunity and cellular immunity. However, protective antigens and nucleic acids recombined into bacterial vector vaccines are difficult to be released into host cells because of the presence of bacterial cell wall. Vaccine strains that are residual in animals or livestock products may also cause environmental contamination and spread of the vaccine strains. The effective solution for these problems is to construct an auto-lysis system that can regulate the vaccine strains to grow normally in vitro while lysis in vivo. The lysis systems that have been applied in germs mainly include: the lysis system based on regulated delayed peptidoglycan synthesis, the lysis system based on the regulation of bacteriophage lysis protein and the lysis system based on the toxin-antitoxin system. In addition, a potential lysis system based on bacterial Type Ⅵ Secretion System (T6SS) is also expected to be a new method for the construction of auto-lysis strains. This review will focus on the regulatory mechanisms of these bacterial lysis systems.
Subject(s)
Animals , Antigens, Bacterial , Bacterial Vaccines , Vaccines, Attenuated , Vaccines, DNAABSTRACT
Objective To investigate neurological function, volume of cerebral infarction, changes of lipid peroxidation, and the intervention effect of compound angelica injection (CAI) on rats with focal cerebral ischemia injury. Methods Models of rat with cerebral ischemia were reproduced by middle cerebral artery occlusion (MCAO). All animals were randomly divided into sham-operation group, model group, CAI group, and edaravone group. 1 hour after the models were established, rats in the sham-operation group and model group received intraperitoneal injection with normal saline, while rats in CAI group and edaravone group received intraperitoneal injection with relevant medicine for continuing 7 days. Volume of cerebral infarction was detected by Tetrazole staining method, neurologic function were detected by neuroethology, and concentration of MDA in brain tissue was also detected. Results After 7-day cerebral ischemia, compared with the model group, volume of cerebral infarction in CAI group was significantly reduced (P<0.05), and the concentration of MDA was a little lower. Conclusion CAI has significant protective effects which can significantly improve neurological function, reduce volume of cerebral infarction, and alleviate the effects of lipid peroxidation of rats with focal cerebral ischemia injury.
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Objective To investigate the effect of Buyang Huanwu Decoction on blood-brain barrier of focal cerebral ischemia rats, and explore the mechanism of the decoction. Methods The model of focal cerebral ischemia was made by thread embolism method. SD rats were divided randomly into sham-operated group, model group and Buyang Huanwu Decoction group. Buyang Huanwu Decoction group was given Buyang Huanwu Decoction by gavage, the sham-operated group and model group were given normal saline of the same quantity 24 h after modeling. The nervous function deficit scores was evaluated, brain tissues and serum were taken from the rats after treating for seven days, infarct volume was detected by TTC staining, and pathological changes of microvessel were observed microscopically in HE stained sections. And the protein level of MMP-9, MMP-2, VEGF in brain tissue and the serum levels of vWF in serum of every groups were measured by ELISA. Results Compared with model group, Buyang Huanwu Decoction significantly improved the neurological behavior performance, decreased the cerebral infarct volume, alleviated the pathological changes and decreased the protein level of MMP-9, MMP-2, VEGF, vWF. Conclusion Buyang Huanwu Decoction has the protective effect on blood-brain barrier in the model rats of focal cerebral ischemia. The mechanism may be related with restrainning the expression of MMP-9, MMP-2, VEGF, vWF.
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Objective To investigate the protective effects of insulin like growth factor 1(IGF-1) on cortical neurons under condition of hypoxia and the possible mechanism. Methods Cerebral cortical neurons from newborn rats were cultured under the condition of oxygen and glucose deprivation (OGD) . On day 7, neurons were treated with IGF-1 or IGF-1 plus LY294002 or PD98059 under condition of OGD or normal condition. MTT assay was used to analyze the viability of neurons in each group. The expression of total Akt and p-Akt were analyzed by Western blot. Results Compared with the control, the neuron viability was significantly higher in IGF-1 treated group under normal or OGD condition (P＜0.05). The protective effects of IGF-1 were attenuated in the presence of LY294002 but not PD98059. The result of Western blot showed IGF-1 upregulated the expression of p-Akt, which was inhibited by LY294002. Conclusion PI3K pathway may play an important role in neuroprotection afforded by IGF-1.