Résumé
BACKGROUND: How to regulate the secretion of vascular endothelial growth factor from dental pulp stem cells is of great significance for promoting dental pulp regeneration by dental pulp stem cells, especially promoting dentinogenesis, dental pulp angiogenesis and neurogenesis. OBJECTIVE: To review the factors affecting the secretion of vascular endothelial growth factor from dental pulp stem cells, providing ideas for pulp regeneration and other clinical applications. METHODS: We searched the articles in PubMed, CNKI, WanFang databases with the keywords of “vascular endothelial growth factor; dental pulp stem cell; dental pulp regeneration; hypoxia; inflammatory mediator; bacterial virulence factor; growth factor; material” in Chinese and English, respectively. Finally, 56 articles met the criteria for review. RESULTS AND CONCLUSION: Vascular endothelial growth factor is the most important cytokine in angiogenesis and neovasculization, which promotes the proliferation and differentiation of stem cells as well as protecting nerves and promoting neurogenesis. Dental pulp stem cells are the most important stem cells in dental pulp tissues. They are also important seed cells in pulp regeneration. Dental pulp stem cells have biological characteristics such as high proliferation, self-renewal and multi-lineage differentiation, and have certain secretory activities, which can be used as an alternative source of exogenous vascular endothelial growth factor. A variety of factors, such as hypoxia, bacterial virulence factors, inflammatory factors, growth factors and materials, are associated with the cytokine secretion activity of dental pulp stem cells, which can affect the expression and secretion of vascular endothelial growth factor in dental pulp stem cells. Therefore, increasing concern has been emphasized on the regulation of vascular endothelial growth factor ecpression and secretion in dental pulp stem cells and the better use in pulp regeneration.
Résumé
TA (Toxin-Antitoxin) systems are widely spread in chromosomes and plasmids of bacteria and archaea. These systems consist of two co-expression genes, encoding stable toxin and sensitive antitoxin, respectively. The toxicity of toxins usually inhibits bacterial growth and antitoxins can neutralize the toxins. Interaction between them would regulate the growth state of bacteria precisely. According to the composition of TA and nature of antitoxin, six types of TA have been found. The role of these TA systems in bacteria has been a hot research topic in recent years. Now, the research status on functions of bacterial TA is reviewed.
Résumé
The amount of iron that might be readily available to bacteria in body fluids is extremely small. This iron restricted environment induces phenotypic changes in the metabolism and in the composition of the membrane proteins of bacteria growing in vivo. These changes are now providing a fresh insight into the capabilities of bacteria to multiply in host tissues and are suggesting new possibilities for targetting therapeutic and prophylactic measures.