ABSTRACT
@#Abstract: Objective To detect and analyze the antiserum of Yersinia pestis phage in Marmota himalayana blood from the natural plague foci of Qinghai-Tibet Plateau by micro-bolus technique, to provide a theoretical basis for interaction between phages and mammalian immunology, phage therapy and interaction between bacteriophage and ecology in future. Methods Using diagnostic Yersinia pestis phage and 3 wild plague phages from Qinghai-Tibet Plateau Natural Plague Foci as antigens, 847 serums of Marmota Himalayana blood, from Tongde, Guinan, Gonghe, Xinghai, Tianjun foci counties in Qinghai Plateau, were collected from July to September in 2020, 2021 and determined on antiserum of Yersinia pestis phage by microplate method and double agar plate method. Results The neutralization reaction experiment lasted for 24 hours between 4 phage and 847 serums by microplate method independently. These mixtures were tested by double agar plate method. All results were negative on antiserum of Yersinia pestis bacteriophage. Conclusions The positive antiserum of Yersinia pestis phage in Marmota himalayana were not found the natural plague foci of Qinghai-Tibet Plateau, which agreed with plague epidemiology in 5 foci counties in Qinghai plateau from 2020-2021, that was a characteristic of the resting period. In other words, it was in the absence of plague pathogen. It also showed indirectly that the absence or weak presence of Yersinia pestis bacteriophage in the plague foci. It showed a lower frequency on host animals coming into contact with phages naturally. The antiserum of Yersinia pestis phage may be related to the form of plague infection and the intensity of the disease.
ABSTRACT
Abstract The aim of this study was to investigate the effect of TiO2/N-succinyl-chitosan composite (TiO2/ NSCS) photodynamic therapy (PDT), while considering the effects of various light sources on the activation of photosensitizer. The methyl thiazolyl tetrazolium assay was used to examine the cell survival rate of the cells. The results showed that glioma cell strain (U251) was the most sensitive cancer cell strain to TiO2/NSCS. When the concentration of TiO2/NSCS was between 0 and 800 μg·mL-1, there was no obvious cytotoxicity to normal liver cells (HL-7702) and U251 cells. During the PDT process, the photokilling effect of TiO2/NSCS on U251 cells under ultraviolet-A (UVA) light irradiation was stronger than that of pure TiO2, and its killing effects were positively correlated with concentration and irradiation time. In addition, both UVA and visible light could excite TiO2/ NSCS, which had significant killing effect on U251 cells. The results of acridine orange/ethidium bromide fluorescent double staining and Annexin V/propidium iodide double staining indicated that TiO2/NSCS under UVA and visible light irradiation could kill U251 cells by inducing apoptosis, and the apoptosis rate of TiO2/NSCS treatment groups was higher than that of TiO2 treatment groups. Therefore, TiO2/NSCS might be used as a potential photosensitizer in PDT.