ABSTRACT
【Objective】 To explore the plasma-activated medium (PAM) produced by low temperature plasma (LTP) on the proliferation and angiogenesis of human umbilical vein endothelial cells (HUVECs) so as to provide theoretical basis for the future use of PAM to promote wound healing and inhibit tumor angiogenesis. 【Methods】 HUVECs were selected as the in vitro research model. The PAM-containing medium after LTP treatment for different time points (0 s, 15 s, 30 s, 45 s, 60 s, and 75 s) was used for intervention. The influence of PAM on HUVECs viability was assessed using the MTT assay and cell cycle analysis. The effects of PAM on angiogenesis were examined through angiogenesis experiments. Intracellular levels of reactive oxygen species (ROS) were measured using fluorescence probes. A melanoma mouse model was established, and CD31 expression was detected by immunohistochemistry. 【Results】 As the treatment time increased, the intracellular levels of ROS also elevated. PAM derived from LTP exhibited a bidirectional effect on angiogenesis in HUVECs. Compared to the control group (0 s), low-dose treatments (15 s and 30 s) enhanced HUVECs viability, while high-dose treatments (45 s, 60 s, and 75 s) significantly decreased cell viability (P<0.05). The proportion of HUVECs in the S phase was significantly increased in the PAM-15 s and PAM-30 s groups, but markedly decreased in the PAM-45 s, PAM-60 s, and PAM-75 s groups, with statistically significant differences (P<0.05). The HUVECs tube formation ability was enhanced in the 15 s and 30 s PAM groups, but diminished in the PAM-45 s, PAM-60 s, and PAM-75 s groups, characterized by the decreased numbers of vascular nodes, intersections, meshes, and branching points (P<0.05). After PAM treatment in the melanoma mouse model, the control group exhibited widespread distribution of CD31 in tumor tissue, while the PAM-5 min and PAM-10 min groups displayed reduced distribution of CD31. 【Conclusion】 Short-term exposure to PAM enhances HUVECs proliferation and angiogenesis, whereas prolonged exposure suppresses cell viability and inhibits angiogenesis.
ABSTRACT
【Objective】 Escherichia coli phage (ECP) and Staphylococcus aureus phage (SAP) isolated from sewage were used as research objects, and their biological characteristics were analyzed to provide new experimental materials for the application of phages. 【Methods】 ECP and SAP were purified and cultured by double-layer agar method. Then a series of biological characteristics of these two phages were preliminarily analyzed by electron microscope observation, optimal multiplicity of infection (MOI) test, one-step growth curve test, temperature, pH, chloroform and ultraviolet sensitivity tests, respectively. 【Results】 The results of biological characteristics showed that ECP and SAP were both virulent phages, belonging to myoviridac family. Their optimal MOI was 10-1, and they had strong resistance to ultraviolet light. The cleavage volume of ECP was 76.3 PFU/cell, while that of SAP was 8.3 PFU/cell. ECP had a wide range of temperature tolerance and could stably survive at 30-50 ℃, while SAP was more sensitive to temperature and could be completely inactivated at 50 ℃ for 1 h. ECP could maintain a good lysis activity in the range of pH 5-11, while SAP in the range of pH 6-9. ECP had strong resistance to chloroform and was non-membranous phage, while SAP was more sensitive to chloroform and was a membranous phage. 【Conclusion】 ECP and SAP are both virulent phages and have strong resistance to ultraviolet light. The lysability, temperature, pH, and chloroform tolerance of ECP are stronger than those of SAP.
ABSTRACT
【Objective】 To observe the inactivation effect of a new low-temperature plasma air disinfector on microorganisms in the natural environment and artificial contaminated environment so as to further determine the minimum effective processing parameters. 【Methods】 First， in 0.5 m3 of super clean workbench and 1.05 m3 airtight organic glass cavity in the body， the new low-temperature plasma air disinfector developed was used to inactivate the natural bacteria in the air under different parameters. Then in 1.05 m3 airtight organic glass cavity in the body， the new low-temperature plasma air disinfector was used to treat the Staphylococcus aureus and Escherichia coli under the condition of artificial bacteria spraying. Last， the plate counting method was used to evaluate the inactivation effect of the disinfector on natural bacteria and artificial bacteria in the air. 【Results】 For the low-temperature plasma air disinfector in 0.5 m3 and 1.05 m3 confined space， the lowest effective treatment parameters for inactivated natural bacteria were 13 kV， 5 min or 12 kV， 10 min. For the low-temperature plasma air disinfection machine in 13 kV discharge voltage treatment of different time， compared with before treatment， the killing rate of Escherichia coli and Staphylococcus aureus increased significantly after treatment for 20 min （P<0.000 1）. Both could meet the requirements of disinfection specifications ［100%， （99.98±0.01）%≥99.90%］. 【Conclusion】 The inactivation of natural bacteria and artificial bacteria by the new low-temperature plasma air disinfector has reached the qualified standard of disinfection stipulated in Technical Specifications for Disinfection.