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ABSTRACT: 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.International Journal of Oral Science (2013) 5, doi:10.1038/ijos.2013.15; published online 29 March 2013.
International Journal of Oral Science 03/2013; 5. · 1.41 Impact Factor
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ABSTRACT: 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.
PLoS ONE 01/2013; 8(2):e56343. · 4.09 Impact Factor
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ABSTRACT: To investigate the effect of Streptococcus mutans luxS gene on polysaccharide matrix metabolism.
Based on the immobilization of magnetic beads by adherent cells,an assay of biofilm quantitative analysis was developed for the kinetic quantification of biofilm formation. S.mutans luxS gene mutant strain and wild-type strain were compared for their ability of utilizing exogenous carbohydrate to form extracellular polysaccharide matrix. SPSS 10.0 software package was used for statistical analysis. Dunnet t two-side test of one factor analysis of variance was performed.
Both luxS mutant strain and wild-type strain could use exogenous carbohydrate to form polysaccharide matrix.With 1% sucrose added ,both strains completed their biofilm formation within one hour.When adding 1% glucose,these strains also accelerated the formation of biofilm,and this was more significant in the mutant strain.
The luxS gene of S. mutans can regulate its extracellular polysaccharide matrix metabolism. Moreover, the regulation of this gene on biofilm formation is more probably via polysaccharide matrix pathway. Supported by National Natural Science Foundation of China(30872886), Research Fund of Science and Technology Commission of Shanghai Municipality(08DZ2271100),Shanghai Leading Academic Discipline Project(S30206) and Youth Phosphor Program of Science and Technology Commission of Shanghai Municipality (09QA1403700).
Shanghai kou qiang yi xue = Shanghai journal of stomatology 02/2011; 20(1):6-9.
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ABSTRACT: This study aimed to evaluate changes in the biodiversity of the oral microflora of patients with head and neck cancer treated with postoperative intensity-modulated radiotherapy (IMRT) or conventional radiotherapy (CRT). Pooled dental plaque samples were collected during the radiation treatment from patients receiving IMRT (n = 13) and CRT (n = 12). Denaturing gradient gel electrophoresis (DGGE) was used to analyze the temporal variation of these plaque samples. The stimulated and unstimulated salivary flow rates were also compared between IMRT and CRT patients. Reductions in the severity of hyposalivation were observed in IMRT patients compared with CRT patients. We also observed that the temporal stability of the oral ecosystem was significantly higher in the IMRT group (69.96 ± 7.82%) than in the CRT group (51.98 ± 10.45%) (P < 0.05). The findings of the present study suggest that IMRT is more conducive to maintaining the relative stability of the oral ecosystem than CRT.
Journal of Radiation Research 01/2011; 52(6):834-9. · 1.68 Impact Factor
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ABSTRACT: The purpose of this study was to develop a mathematical model to quantitatively describe the passive transport of macromolecules within dental biofilms.
Fluorescently labeled dextrans with different molecular mass (3 kD, 10 kD, 40 kD, 70 kD, 2000 kD) were used as a series of diffusion probes. Streptococcus mutans, Streptococcus sanguinis, Actinomyces naeslundii and Fusobacterium nucleatum were used as inocula for biofilm formation. The diffusion processes of different probes through the in vitro biofilm were recorded with a confocal laser microscope.
Mathematical function of biofilm penetration was constructed on the basis of the inverse problem method. Based on this function, not only the relationship between average concentration of steady-state and molecule weights can be analyzed, but also that between penetrative time and molecule weights.
This can be used to predict the effective concentration and the penetrative time of anti-biofilm medicines that can diffuse through oral biofilm. Furthermore, an improved model for large molecule is proposed by considering the exchange time at the upper boundary of the dental biofilm.
International Journal of Oral Science 12/2010; 2(4):190-7. · 1.41 Impact Factor
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ABSTRACT: To investigate the effect of Streptococcus mutans luxS mutarotation on the early biofilm formation.
Based on the immobilization of magnetic beads by adherent cells, an assay of biofilm quantitative analysis was developed for the kinetic quantification of biofilm formation in this study. Streptococcus mutans luxS mutant strain was constructed and subject to this biofilm luxS mutant strain were compared.
The delta luxS mutant started to form a biofilm from the 6th hour (delta BFI = 2.015), and the delta BFI of luxS mutant increased more quickly than that of the wild type strain, until reaching a complete immobilization of the beads after 10 hours (delta BFI = 7.025). The wild-type strain start to form a biofilm from the 10 th hour (delta BFI = 1.875) and the beads were completely immobilized between 12 and 14 hours.
The luxS mutation can accelerate biofilm on a polystyrene surface during the mid-exponential growth phase. And a luxS-dependent signal may play an important role in the early biofilm formation of Streptococcus mutans.
Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology 03/2009; 44(2):72-5.
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ABSTRACT: It is reported that Streptococcus mutans luxS gene may have an important role in the interspecies quorum sensing system. To construct the S. mutans luxS gene knockout mutant, this research aim to construct the luxS gene allelic exchange plasmid.
The upstream and downstream flank DNA fragments of S. mutans luxS gene (Xup, Xdn)and the E. coli kanamycin resistance gene (Kana) were enriched by pfu DNA polymerase with "nest PCR" methods. These fragments were ligated into pBluescript SK (+) Phagemids vector with double endonuclease reaction sequentially.
With endonuclease reaction and DNA sequencing, it was proved that the objective plasmid, Xukd-pbsk, was constructed correctively and the kanamycin resistance gene could be expressed in vitro.
The S. mutans luxS gene allelic exchange plasmid is constructed correctively in this research and can be used in the future research of S. mutans luxS gene knockout mutant.
Hua xi kou qiang yi xue za zhi = Huaxi kouqiang yixue zazhi = West China journal of stomatology 03/2006; 24(1):70-2.
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ABSTRACT: To obtain the clone of conserved fragment of urease gene of Staphylococcus warneri.
Urease activity was measured by phenol red assay. An internal fragment of the urease gene of Staphylococcus warneri was amplified by PCR with primers derived from conserved amino acid sequences of the large subunit of urease. The PCR product was then cloned into T-vector and sequenced.
Urease activity of Staphylococcus warneri was positive. The internal fragment of urease gene of Staphylococcus warneri was highly homologous to known urease gene cluster of other bacteria.
In this study, urease activity of Staphylococcus warneri was proved and the internal fragment of urease gene encoding conserved amino acid sequences was cloned.
Shanghai kou qiang yi xue = Shanghai journal of stomatology 03/2006; 15(1):66-8.
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ABSTRACT: To compare the antibacterial effect between sodium fluoride and Galla Chinesis in bioflim model. To evaluate the feasibility of application of Gala Chinesis in the clinical practice of caries prevention.
Streptococcus mutans, Streptococcus sanguis, Streptococcus salivarius and Actinomyces naeslundii had been chosen as the experimental bacteria. In the experiment, biofilmn model was constructed, and two agents were added in the media. After a period of continuous culture, the number of bacteria adhering on the HA disc was examed, the planktonic pH in the flow cell was recorded continuously, and the morphology of the biofilmn formed on the HA disc was observed by SEM.
(1) Galla Chinesis could inhibit the growth of the four oral bacteria in the biofilm just as sodium fluoride. (2) Galla Chinesis and sodium fluoride could prevent the descent of the planktonic pH in the flow cell, but Galla Chinesis was less efficient than sodium fluoride. (3) The biofilms formed after application of Galla Chinesis and fluoride, but the bacterial cells had less matrix than those applicated with sucrose.
Galla Chinesis is one kind of effective cariostatic natural agents.
Hua xi kou qiang yi xue za zhi = Huaxi kouqiang yixue zazhi = West China journal of stomatology 11/2005; 23(5):367-9.
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ABSTRACT: To study the effect of 11 different natural drugs on the growth and acid production of Lactobacillus, as a preparation for screening an effective agent to mediate the balance of oral microflora.
Lactobacillus AC413 was chosen as the experimental bacterium. Eleven kinds of drugs, such as Rhizoma Chuanxiong, Surgentodoxa cuneata and Galla Chinensis were extracted by means of maceration, percolation and reflux extraction. The values of MIC of various extracts were measured. Then, different experimental media containing various extracts were prepared. The concentration of the extracts was lower than the MIC of the drug and the initial pH of the medium was 7.4. Lactobacillus was cultured in the medium for 48 hours, and finally the rest pH was measured. One-way ANOVA was used for statistical analysis.
When the concentration of the drugs was lower than 8.000mg/ml, Tea polyphenols, Catechu, Galla Chinensis, Radix et Rhizoma Rhei and Nidus Vespae can inhibit the growth of Lactobacillus effectively. Tea polyphenols, Nidus Vespae, Radix Scuteilariae, Galla Chinensis and Surgentodoxa cuneata can inhibit the acid production of Lactobacillus effectively, Rhizoma Chuanxiong, Radix et Rhizoma Rhei, Semen Arecae and Catechu have no preliminary effect on it, but Surgentodoxa Cuneata and Radix Angelicae Pubescentis can increase it.
Tea polyphenols, Catechu, Galla Chinensis, Radix et Rhizoma Rhei and Nidus Vespae can inhibit the growth of Lactobacillus effectively, and Tea polyphenols, Radix et Rhizoma Rhei, Nidus Vespae, Radix Scuteilariae, Galla Chinensis and Surgentodoxa Cuneata can inhibit the acid production of Lactobacillus effectively.
Shanghai kou qiang yi xue = Shanghai journal of stomatology 03/2005; 14(1):67-70.
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ABSTRACT: To figure out the reason for increased acid tolerance of Ingbritt-FR, the fluoride-resistant strain of Streptococcus mutans Ingbritt, by determining and comparing the H(+)-ATPase activities of both fluoride-resistant and their parental strains.
The permeabilized cells of S. mutans Ingbritt and Ingbritt-FR were prepared by treating them with 10% toluene and then two cycles of freezing and thawing. The permeabilized cells were used for ATPase assay by adding them to the reaction mixture which contained 50mM Tris-maleate buffer (pH 6.0), 10 mM MgSO4 and 5 mM ATP. ATPase activity was assessed by measuring inorganic phosphate released from ATP hydrolysis.Two-way ANOVA was used for statistical analysis.
The activities of H(+)-ATPase of Ingbritt-FR were 308.48, 136.67, and 82.80 micromol Pi/g cell dry weight/min, at 10, 20, and 60 minutes respectively, significantly higher than those of their parent strain: 104.77, 64.69, and 30.7 (P<0.01). The enzyme activities were decreasing with time.
The higher ATPase activity of fluoride-resistant mutant of S. mutans Ingbritt may account for the increased acid tolerance of this organism, and the increment of ATPase activity and acid tolerance of fluoride-resistant strain is likely to increase the cariogenic potential of S. mutans after fluoride-resistant mutation.
Shanghai kou qiang yi xue = Shanghai journal of stomatology 03/2005; 14(1):71-3.
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ABSTRACT: To investigate the effects of 5 kinds of natural medicine such as Radix et Rhizoma Rhei on the adherence of Streptococcus mutans to salivary acquired pellicle, and to screen effective natural medicines for the prevention of caries.
The in vitro model of experimental pellicle was saliva-coated hydroxyapatites (S-HA). Streptococcus mutans and S-HA were treated with natural medicines respectively, and then the adherence of bacteria to S-HA was tested.
Radix et Rhizoma Rhei, Semen Arecae and Rhizoma Liguistici Chuanxiong could decrease the attachment of Streptococcus mutans to S-HA, and Semen Arecae was the most effective one. Radix Angelicae Dahuricae had no remarkable effect, and Catechu inhibited the adherence only after the bacteria being under treatment.
Radix et Rhizoma Rhei, Semen Arecae, Rhizoma Liquistici Chuanxiong and Catechu could effectively inhibit the adherence of Streptococcus mutans to salivary acquired pellicle, but the effect of Radix Angelicae Dahuricae on the adherence is un-noticeable.
Sichuan da xue xue bao. Yi xue ban = Journal of Sichuan University. Medical science edition 10/2004; 35(5):687-9.
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ABSTRACT: To study the role of Polistes mandarinus on the growth,acid generation and water insoluble glucan(WIG) production of Streptococcus mutans, Streptococcus sanguis and Actinomyces viscosus as a preparation for screening an effective agent ot medicate the balance of oral microflora.
Streptococcus mutans 3a3, Streptococcus sanguis SB 179 and Actinomyces viscosus ATCC 19246 were chosen as the experimental bacteria. The effects of Polistes mandarinus on the growth, acid generation and glucan production were observed.
Polistes mandarinus can inhibit the growth and acid generation of S.mutans,S.sanguis and A.viscosus, and the water-insoluble glucan production of S.mutants and S.sanguis effectively.
Polistes mandarinus can inhibit the growth, acid generation and glucan production of oral bacteria effectively.
Shanghai kou qiang yi xue = Shanghai journal of stomatology 04/2002; 11(1):50-2.
