新型冠状病毒肺炎疫情爆发后,广大护理工作者用自己的实际行动践行着救死扶伤,甘于奉献的崇高精神.重庆市璧山区人民医院从全院抽调精兵强将组建隔离病房,成为抗击疫情的“一线战场”.在这场没有硝烟的战斗中,有这样一批90后女护士,在“一线战场”上用她们的坚毅与执着,诠释白衣天使的职责.

ObjectiveThe aim of this study was to examine the influence of various time intervals on the composition of the supragingival plaque microbiome, especially the dynamic core microbiome, and to find a suitable observation interval for further studies on oral microbiota.Methods and MaterialsEight qualified volunteers whose respective age ranges from 25 to 28 years participated in the present study. The supragingival plaque was collected from the buccogingival surface of the maxillary first molar at eight time slots with different intervals (day 0, 1 day, 3 days, 1 week, 2 weeks, 3 weeks, 1 month, and 3 months). Bioinformatic analyses was performed based on 16S rDNA pyrosequencing (454 sequencing platform) targeting at the hypervariable V4-V5 region, in order to assess the diversity and variation of the supragingival plaque microbiome.ResultsA total of 359,565 qualified reads for 64 samples were generated for subsequent analyses, which represents 8,452 operational taxonomic units identified at 3% dissimilarity. The dynamic core microbiome detected in the current study included five phyla, 12 genera and 13 species. At the genus level, the relative abundance of bacterial communities under the "1 day," "1 month," and "3 months" intervals was clustered into sub-category. At the species level, the number of overlapping species remained stable between the "1 month" and "3 months" intervals, whereas the number of dynamic core species became stable within only 1 week.ConclusionsThis study emphasized the impact of different time intervals (days, weeks and months) on the composition, commonality and diversity of the supragingival microbiome. The analyses found that for various types of studies, the time interval of a month is more suitable for observing the general composition of the supragingival microbiome, and that a week is better for observing the dynamic core microbiome.

Objective: The aim of this article was to study the variation in oral microflora of the subgingival plaque during and after radiotherapy.Design: During and after radiotherapy, microbial samples were collected at seven time points (early stage, medium stage, and later stage of radiotherapy, and 1 month, 3 months, 6 months, and 1 year after radiotherapy) in three subjects for a total of 21 samples. Polymerase chain reaction (PCR) amplification was carried out on the 16S rDNA hypervariable V1-V3 region, and then the PCR products were determined by high-throughput pyrosequencing.Results: The rarefaction curve indicating the richness of the microflora demonstrated that the number of operational taxonomic units (OTUs) was in decline from the early stage of radiotherapy to the time point 1 month after radiotherapy and then trended upward. The Shannon diversity index declined during radiotherapy (ranging from 4.59 to 3.73), and generally rose after radiotherapy, with the lowest value of 3.5 (1 month after radiotherapy) and highest value of 4.75 (6 months after radiotherapy). A total of 120 genera were found; five genera (Actinomyces, Veillonella, Prevotella, Streptococcus, Campylobacter) were found in all subjects across all time points.Conclusion: The richness and diversity of oral ecology decreased with increased radiation dose, and it was gradually restored with time. (C) 2015 Elsevier Ltd. All rights reserved.

The objective of this study was to investigate the compositional profiles and microbial shifts of oral microbiota during head-and-neck radiotherapy. Bioinformatic analysis based on 16S rRNA gene pyrosequencing was performed to assess the diversity and variation of oral microbiota of irradiated patients. Eight patients with head and neck cancers were involved in this study. For each patient, supragingival plaque samples were collected at seven time points before and during radiotherapy. A total of 147,232 qualified sequences were obtained through pyrosequencing and bioinformatic analysis, representing 3,460 species level operational taxonomic units (OTUs) and 140 genus level taxa. Temporal variations were observed across different time points and supported by cluster analysis based on weighted UniFrac metrics. Moreover, the low evenness of oral microbial communities in relative abundance was revealed by Lorenz curves. This study contributed to a better understanding of the detailed characterization of oral bacterial diversity of irradiated patients.

Radiotherapy is the primary treatment modality used for patients with head-and-neck cancers, but inevitably causes microorganism-related oral complications. This study aims to explore the dynamic core microbiome of oral microbiota in supragingival plaque during the course of head-and-neck radiotherapy. Eight subjects aged 26 to 70 were recruited. Dental plaque samples were collected (over seven sampling time points for each patient) before and during radiotherapy. The V1-V3 hypervariable regions of bacterial 16S rRNA genes were amplified, and the high-throughput pyrosequencing was performed. A total of 140 genera belonging to 13 phyla were found. Four phyla (Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria) and 11 genera (Streptococcus, Actinomyces, Veillonella, Capnocytophaga, Derxia, Neisseria, Rothia, Prevotella, Granulicatella, Luteococcus, and Gemella) were found in all subjects, supporting the concept of a core microbiome. Temporal variation of these major cores in relative abundance were observed, as well as a negative correlation between the number of OTUs and radiation dose. Moreover, an optimized conceptual framework was proposed for defining a dynamic core microbiome in extreme conditions such as radiotherapy. This study presents a theoretical foundation for exploring a core microbiome of communities from time series data, and may help predict community responses to perturbation as caused by exposure to ionizing radiation.

Streptococcus mutans is recognised as a major aetiological agent of dental caries. One of its important virulence factors is its ability to form biofilms on tooth surfaces. The aim of this study was to evaluate the effects of the quorum sensing inhibitor furanone C-30 on biofilm formation by S. mutans and its luxS mutant strain. The effects of furanone C-30 on biofilms of both strains formed on 96-well microtitre plates at 37 °C were determined by a colorimetric technique (MTT assay). Different concentrations of furanone C-30 (0.0, 2.0 and 4.0 μg/mL) and different time points of biofilm formation (4, 14 and 24 h) were investigated. The structures and thickness of the biofilms were observed by confocal laser scanning microscopy (CLSM). Quorum sensing-related gene expression (ftf, smu630, brpA, gbpB, gtfB, vicR, comDE and relA) was investigated by real-time polymerase chain reaction (RT-PCR). The results showed that synthetic furanone C-30 can inhibit biofilm formation by S. mutans and its luxS mutant strain, although it does not affect the bacterial growth rate itself. The quantities of biofilm formed by both strains significantly decreased (P < 0.05) and the biofilms became thinner and looser as revealed by CLSM with increasing concentrations of furanone C-30. Expression of the genes tested was downregulated in the biofilms by the addition of furanone C-30. These results revealed that synthetic furanone C-30 can effectively inhibit biofilm formation by S. mutans and its luxS mutant strain.

Objective:To research the effect of quorum sensing inhibitor furanone C-30 on initial biofilm formation of Streptococcus mutans.Methods:The in vitro synthetic quorum sensing inhibitor furanone C-30 was prepared with BHI medium in which Streptococcus mutans was cultivated into different final concentration of 10μmol/L,100μmol/L.Biofilms were formed after being incubaed at 37℃ for 24 h,followed which the kinetic quantification of biofilm formation was detected by BioFilm Ring Test.Results:The furanone C-30 group with a concentration of 100μmol/L was shown to inhibit the biofilm formation by Streptococcus mutans significantly(P0.05).The time of magnetic beads immobilized and the value of BFI were both different between the 100μmol/L furanone C-30 group and the control groups.Conclusions:Quorum sensing inhibitor furanone C-30 in the concentration of 100μmol/L can inhibit the biofilm formation of Streptococcus mutans.It may direct a new way for the prevention and therapy of caries.

AI-2-mediated quorum sensing has been identified in various bacteria, including both Gram-negative and Gram-positive species, and numerous phenotypes have been reported to be regulated by this mechanism, using the luxS-mutant strain. But the AI-2 production process confused this regulatory function; some considered this regulation as the result of a metabolic change, which refers to an important metabolic cycle named activated methyl cycle (AMC), caused by luxS-mutant simultaneously with the defect of AI-2. Herein we hypothesized that the quorum sensing system-not the metabolic aspect-is responsible for such a regulatory function. In this study, we constructed plasmids infused with sahH and induced protein expression in the luxS-mutant strain to make the quorum-sensing system and metabolic system independent. The biofilm-related genes were investigated by real-time polymerase chain reaction (PCR), and the results demonstrated that the quorum-sensing completed strain restored the gene expression of the defective strain, but the metabolically completed one did not. This evidence supported our hypothesis that the autoinducer-2-mediated, quorum-sensing system, not the AMC, was responsible for luxS mutant regulation.

Objective To compare the biofilm early formation ability of Pseudomonas aeruginosa PAO1,Streptococcus mutans UA159 and Escherichia coli MG1655 through a biofilm quantitative analysis named BioFilm Ring Test.Method Based on th eimmobilization of magnetic beads by adherent cells,an assay was developed for the kinetic quantification of biofilm formation in this study.Result There were no significant difference between Pseudomonas aeruginosa PAO1 and Escherichia coli MG1655 in bacterial growth rate.But the biofilm formation speed of Pseudomonas aeruginosa PAO1 was much quicker than that of Escherichia coli MG1655.There were no significant difference between Escherichia coli MG1655 and Streptococcus mutans UA159 in biofilm formation speed.But the bacterial growth rate of Escherichia coli MG1655 was much higher than that of Streptococcus mutans UA159.Conclusion Each bacterial strain has its own special pattern of biofilm formation.The BioFilm Ring Test may be used as a rapid,reproducible and easy-handling method to study the kinetics of bacterial biofilm early formation.

目的 观察上海防酸牙膏(加强型) 治疗牙本质过敏症的临床疗效.方法 采用双盲法对70例牙本质过敏症的患者随机分成A、B2组,每组35例,分别使用上海防酸牙膏和上海防酸牙膏(加强型)2种牙膏,分别记录刷牙前、刷牙8周后Schiff冷空气敏感指数,并进行统计学处理.结果 2组患者使用前的Schiff冷空气敏感指数无统计学差异(P>0.05);使用8周后,A、B2组的Schiff冷空气敏感指数都有降低,且2组之间有统计学差异(P<0.05).揭盲显示,B管牙膏为上海防酸牙膏(加强型).结论 上海防酸牙膏(加强型)对牙本质过敏症具有临床疗效.