The objective of the study was to analyse Streptococcus mutans biofilms grown under different dietary conditions by using multifaceted methodological approaches to gain deeper insight into the cariogenic impact of car...The objective of the study was to analyse Streptococcus mutans biofilms grown under different dietary conditions by using multifaceted methodological approaches to gain deeper insight into the cariogenic impact of carbohydrates. S. mutans biofilms were generated during a period of 24 h in the following media： Schaedler broth as a control medium containing endogenous glucose, Schaedler broth with an additional 5% sucrose, and Schaedler broth supplemented with 1% xylitol. The confocal laser scanning microscopy（CLSM）-based analyses of the microbial vitality, respiratory activity（5-cyano-2,3-ditolyl tetrazolium chloride, CTC） and production of extracellular polysaccharides（EPS） were performed separately in the inner, middle and outer biofilm layers. In addition to the microbiological sample testing, the glucose/sucrose consumption of the biofilm bacteria was quantified, and the expression of glucosyltransferases and other biofilm-associated genes was investigated. Xylitol exposure did not inhibit the viability of S. mutans biofilms, as monitored by the following experimental parameters： culture growth, vitality, CTC activity and EPS production. However,xylitol exposure caused a difference in gene expression compared to the control. Gtf C was upregulated only in the presence of xylitol.Under xylitol exposure, gtf B was upregulated by a factor of 6, while under sucrose exposure, it was upregulated by a factor of three.Compared with glucose and xylitol, sucrose increased cell vitality in all biofilm layers. In all nutrient media, the intrinsic glucose was almost completely consumed by the cells of the S. mutans biofilm within 24 h. After 24 h of biofilm formation, the multiparametric measurements showed that xylitol in the presence of glucose caused predominantly genotypic differences but did not induce metabolic differences compared to the control. Thus, the availability of dietary carbohydrates in either a pure or combined form seems to affect the cariogenic potential of S. mutans biofilms.展开更多
Mechanical alloying and annealing at 1150 °C for 2 h under an argon atmosphere were used to prepare Ti-45S5 bioglass nanocomposites. Ti-45S5 bioglass material was chemically modified by silver. The antibacterial ...Mechanical alloying and annealing at 1150 °C for 2 h under an argon atmosphere were used to prepare Ti-45S5 bioglass nanocomposites. Ti-45S5 bioglass material was chemically modified by silver. The antibacterial activity of Ti-10% 45S5 bioglass nanocomposite containing silver against Streptococcus mutans and Staphylococcus aureus was studied. Nanocomposites were characterized by X-ray diffraction, scanning electron microscopy equipped with an electron energy dispersive spectrometer and transmission electron microscopy to evaluate phase composition, crystal structure and grain size. In vitro bacterial adhesion study indicated a significantly reduced number of Streptococcus mutans and Staphylococcus aureus on the bulk nanostructured Ti-45S5 bioglass-Ag plate surface in comparison to that on microcrystalline Ti plate surface. Nanostructured Ti-based biomaterials can be considered to be the future generation of dental implants.展开更多
objective: construct a homologous recombinant plasmid which was expected to be transformed into S.mutans Methods: a region at the 5’terminus of the S.mutans F-ATPase β subunit gene was amplified by PCR, the PCR prod...objective: construct a homologous recombinant plasmid which was expected to be transformed into S.mutans Methods: a region at the 5’terminus of the S.mutans F-ATPase β subunit gene was amplified by PCR, the PCR product was inserted into vector pVA891,yielding recombinant plasmid.Results: the DNA sequence of the recombinant plasmid was identified correct in whole by restriction endonuclease and DNA sequence techniques.Conclusion: the recombinant plasmid of S.mutans DNA was cloned in effect,it may assist in construction of homologues recombinant mutant.展开更多
Tooth decay affects most of the population in developed countries. The multifactorial etiology of the disease includes multiple bacterial species, S. mutans is the main pathogen associated with the disease. This bacte...Tooth decay affects most of the population in developed countries. The multifactorial etiology of the disease includes multiple bacterial species, S. mutans is the main pathogen associated with the disease. This bacterium adheres to the tooth surface and allows the colonization of other microorganisms resulting in dental biofilm. Several therapeutic agents are available to treat or prevent tooth decay, but none, with the exception of fluoride, has significantly influenced the disease’s global burden. Moreover, the probable development of resistance of microorganisms to existing antibacterial agents and the scarcity of good antimicrobial agents motivates this effort for innovation. The detailed knowledge obtained in recent years on the S. mutans allowed the identification of potential targets in this microorganism, enabling the development of specific drugs to combat tooth decay. Thus, the identification of potential targets in these pathogens is the first step in the discovery process of new therapeutic agents. Currently, the experimental assays used for this purpose are expensive and time consuming. In contrast, bioinformatics methods to predict drug targets are cheap, quick and workaday in the biotechnology. This article will review the potential drug targets in S. mutans, as well as the bioinformatics methods used to identify these targets and effective drugs for specific pharmacological treatment of dental caries.展开更多
The novel quaternary ammonium bromide (QAB)-containing oligomers were synthesized and applied for developing an antibacterial resin composite. Compressive strength (CS) and S. mutans (an oral bacteria strain) viabilit...The novel quaternary ammonium bromide (QAB)-containing oligomers were synthesized and applied for developing an antibacterial resin composite. Compressive strength (CS) and S. mutans (an oral bacteria strain) viability were used to evaluate the mechanical strength and antibacterial activity of the formed composites. All the QAB-modified resin composites showed significant antibacterial activity and mechanical strength reduction. Increasing chain length and loading significantly enhanced the antibacterial activity but dramatically reduced the CS as well. The 30-day aging study showed that the incorporation of the QAB accelerated the degradation of the composite, suggesting that the QAB may not be well suitable for development of antibacterial dental resin composites or at least the QAB loading should be well controlled, unlike its use in dental glass-ionomer cements. The work in this study is beneficial and valuable to those who are interested in studying antibacterial dental resin composites.展开更多
The construction of the first infectious clone JFH-1 speeds up the research on hepatitis C virus (HCV). However, Huh7 cell line was the only highly permissive cell line for HCV infection and only a few clones were ful...The construction of the first infectious clone JFH-1 speeds up the research on hepatitis C virus (HCV). However, Huh7 cell line was the only highly permissive cell line for HCV infection and only a few clones were fully permissive. In this study, two different fully permissive clones of Huh7 cells, Huh7.5.1 and Huh7-Lunet-CD81 (Lunet-CD81) cells were compared for their responses upon HCV infection. The virus replication level was found slightly higher in Huh7.5.1 cells than that in Lunet-CD81 cells. Viability of Huh7.5.1 cells but not of Lunet-CD81 cells was reduced significantly after HCV infection. Further analysis showed that the cell cycle of infected Huh7.5.1 cells was arrested at G1 phase. The G1/S transition was blocked by HCV infection in Huh7.5.1 cells as shown by the cell cycle synchronization analysis. Genes related to cell cycle regulation was modified by HCV infection and gene interaction analysis in GeneSpring GX in Direct Interactions mode highlighted 31 genes. In conclusion, the responses of those two cell lines were different upon HCV infection. HCV infection blocked G1/S transition and cell cycle progress, thus reduced the cell viability in Huh7.5.1 cells but not in Lunet-CD81 cells. Lunet-CD81 cells might be suitable for long term infection studies of HCV.展开更多
This study reports the synthesis and evaluation of a novel furanone-containing antibacterial resin composite. Compres-sive strength (CS) and S. mutans viability were used to evaluate the mechanical strength and antiba...This study reports the synthesis and evaluation of a novel furanone-containing antibacterial resin composite. Compres-sive strength (CS) and S. mutans viability were used to evaluate the mechanical strength and antibacterial activity of the composites. With 5% to 30% addition of the furanone derivative, the composite showed no change in CS but a significant antibacterial activity with a 16% - 68% reduction in the S. mutans viability. Further, the antibacterial activity of the modified composite was not affected by human saliva. The aging study implies that the modified composite may have a long-lasting antibacterial function. Within the limitations of this study, it appears that this experimental resin composite may potentially be developed into a clinically attractive dental restorative due to its high mechanical strength and antibacterial function.展开更多
A novel antibacterial glass-ionomer cement has been developed. Compressive strength (CS) and S. mutans viability were used to evaluate the mechanical strength and antibacterial activity of the formed cement. Compressi...A novel antibacterial glass-ionomer cement has been developed. Compressive strength (CS) and S. mutans viability were used to evaluate the mechanical strength and antibacterial activity of the formed cement. Compressive yield strength (YS), modulus (M), diametral tensile strength (DTS) and flexural strength (FS) were also determined. All the formulated antibacterial cements showed a significant antibacterial activity, accompanying with an initial CS reduction. The effect of the synthesized antibacterial polymer loading was significant. Increasing loading from 1% to 20% significantly decreased the S. mutans viability from 3% to 50% and also reduced the initial CS (325 MPa) of the formed cements from 19% to 75%. The cement with 5% antibacterial polymer loading showed 142 MPa, 6.9 GPa, 224 MPa, 52 MPa, and 62 MPa in YS, M, CS, DTS and FS, respectively, as compared to 170, 7.1, 325, 60 and 87 for the experimental cement without antibacterial polymer addition and 141, 6.9, 236, 42 and 53 for Fuji II LC. It was also found that the chlorine-containing antibacterial cement showed better CS values than the bromine-containing cement, with no significant difference in antibacterial activity. The antibacterial cement also showed a similar antibacterial activity to Streptococcus mutans, lactobacillus, Staphylococcus aureus and Staphylococcus epidermidis. The human saliva did not affect the antibacterial activity of the cement. The thirty-day aging study indicates that the cements may have a long-lasting antibacterial function.展开更多
Both genetic and environmental factors are important in the pathogenesis of Parkinson＇s disease. As α-synuclein is a major constituent of Lewy bodies, a pathologic hallmark of Parkinson＇s disease, genetic aspects ...Both genetic and environmental factors are important in the pathogenesis of Parkinson＇s disease. As α-synuclein is a major constituent of Lewy bodies, a pathologic hallmark of Parkinson＇s disease, genetic aspects of α-synuclein is widely studied. However, the influence of dietary factors such as quercetin on α-synuclein was rarely studied. Herein we aimed to study the neuroprotective role of quercetin against various toxins affecting apoptosis, autophagy and aggresome, and the role of quercetin on α-synuclein expression. PC12 cells were pre-treated with quercetin（100, 500, 1,000 μM） and then together with various drugs such as 1-methyl-4-phenylpyridinium（MPP＋; a free radical generator）, 6-hydroxydopamine（6-OHDA; a free radical generator）, ammonium chloride（an autophagy inhibitor）, and nocodazole（an aggresome inhibitor）. Cell viability was determined using a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltertazolium bromide（MTT） assay. Apoptosis was detected by annexin V-fluorescein isothiocyanate and propidium iodide through the use of fluorescence activated cell sorter. α-Synuclein expression was detected by western blot assay and immunohistochemistry. The role of α-synuclein was further studied by knocking out α-synuclein using RNA interference. Cell viability increased at lower concentrations（100 and 500 μM） of quercetin but decreased at higher concentration（1,000 μM）. Quercetin exerted neuroprotective effect against MPP＋, ammonium chloride and nocodazole at 100 μM. MPP＋ induced apoptosis was decreased by 100 μM quercetin. Quercetin treatment increased α-synuclein expression. However, knocking out α-synuclein exerted no significant effect on cell survival. In conclusion, quercetin is neuroprotective against toxic agents via affecting various mechanisms such as apoptosis, autophagy and aggresome. Because α-synuclein expression is increased by quercetin, the role of quercetin as an environmental factor in Parkinson＇s disease pathogenesis needs further investigation.展开更多
基金supported by the National Deutsche Gesellschaft fr Zahnerhaltung-GABA Scientific Fund, Germany
文摘The objective of the study was to analyse Streptococcus mutans biofilms grown under different dietary conditions by using multifaceted methodological approaches to gain deeper insight into the cariogenic impact of carbohydrates. S. mutans biofilms were generated during a period of 24 h in the following media： Schaedler broth as a control medium containing endogenous glucose, Schaedler broth with an additional 5% sucrose, and Schaedler broth supplemented with 1% xylitol. The confocal laser scanning microscopy（CLSM）-based analyses of the microbial vitality, respiratory activity（5-cyano-2,3-ditolyl tetrazolium chloride, CTC） and production of extracellular polysaccharides（EPS） were performed separately in the inner, middle and outer biofilm layers. In addition to the microbiological sample testing, the glucose/sucrose consumption of the biofilm bacteria was quantified, and the expression of glucosyltransferases and other biofilm-associated genes was investigated. Xylitol exposure did not inhibit the viability of S. mutans biofilms, as monitored by the following experimental parameters： culture growth, vitality, CTC activity and EPS production. However,xylitol exposure caused a difference in gene expression compared to the control. Gtf C was upregulated only in the presence of xylitol.Under xylitol exposure, gtf B was upregulated by a factor of 6, while under sucrose exposure, it was upregulated by a factor of three.Compared with glucose and xylitol, sucrose increased cell vitality in all biofilm layers. In all nutrient media, the intrinsic glucose was almost completely consumed by the cells of the S. mutans biofilm within 24 h. After 24 h of biofilm formation, the multiparametric measurements showed that xylitol in the presence of glucose caused predominantly genotypic differences but did not induce metabolic differences compared to the control. Thus, the availability of dietary carbohydrates in either a pure or combined form seems to affect the cariogenic potential of S. mutans biofilms.
文摘Mechanical alloying and annealing at 1150 °C for 2 h under an argon atmosphere were used to prepare Ti-45S5 bioglass nanocomposites. Ti-45S5 bioglass material was chemically modified by silver. The antibacterial activity of Ti-10% 45S5 bioglass nanocomposite containing silver against Streptococcus mutans and Staphylococcus aureus was studied. Nanocomposites were characterized by X-ray diffraction, scanning electron microscopy equipped with an electron energy dispersive spectrometer and transmission electron microscopy to evaluate phase composition, crystal structure and grain size. In vitro bacterial adhesion study indicated a significantly reduced number of Streptococcus mutans and Staphylococcus aureus on the bulk nanostructured Ti-45S5 bioglass-Ag plate surface in comparison to that on microcrystalline Ti plate surface. Nanostructured Ti-based biomaterials can be considered to be the future generation of dental implants.
文摘objective: construct a homologous recombinant plasmid which was expected to be transformed into S.mutans Methods: a region at the 5’terminus of the S.mutans F-ATPase β subunit gene was amplified by PCR, the PCR product was inserted into vector pVA891,yielding recombinant plasmid.Results: the DNA sequence of the recombinant plasmid was identified correct in whole by restriction endonuclease and DNA sequence techniques.Conclusion: the recombinant plasmid of S.mutans DNA was cloned in effect,it may assist in construction of homologues recombinant mutant.
文摘Tooth decay affects most of the population in developed countries. The multifactorial etiology of the disease includes multiple bacterial species, S. mutans is the main pathogen associated with the disease. This bacterium adheres to the tooth surface and allows the colonization of other microorganisms resulting in dental biofilm. Several therapeutic agents are available to treat or prevent tooth decay, but none, with the exception of fluoride, has significantly influenced the disease’s global burden. Moreover, the probable development of resistance of microorganisms to existing antibacterial agents and the scarcity of good antimicrobial agents motivates this effort for innovation. The detailed knowledge obtained in recent years on the S. mutans allowed the identification of potential targets in this microorganism, enabling the development of specific drugs to combat tooth decay. Thus, the identification of potential targets in these pathogens is the first step in the discovery process of new therapeutic agents. Currently, the experimental assays used for this purpose are expensive and time consuming. In contrast, bioinformatics methods to predict drug targets are cheap, quick and workaday in the biotechnology. This article will review the potential drug targets in S. mutans, as well as the bioinformatics methods used to identify these targets and effective drugs for specific pharmacological treatment of dental caries.
文摘The novel quaternary ammonium bromide (QAB)-containing oligomers were synthesized and applied for developing an antibacterial resin composite. Compressive strength (CS) and S. mutans (an oral bacteria strain) viability were used to evaluate the mechanical strength and antibacterial activity of the formed composites. All the QAB-modified resin composites showed significant antibacterial activity and mechanical strength reduction. Increasing chain length and loading significantly enhanced the antibacterial activity but dramatically reduced the CS as well. The 30-day aging study showed that the incorporation of the QAB accelerated the degradation of the composite, suggesting that the QAB may not be well suitable for development of antibacterial dental resin composites or at least the QAB loading should be well controlled, unlike its use in dental glass-ionomer cements. The work in this study is beneficial and valuable to those who are interested in studying antibacterial dental resin composites.
基金supported partly by grants of National Nature Science Foundation of China (grant 31200135)
文摘The construction of the first infectious clone JFH-1 speeds up the research on hepatitis C virus (HCV). However, Huh7 cell line was the only highly permissive cell line for HCV infection and only a few clones were fully permissive. In this study, two different fully permissive clones of Huh7 cells, Huh7.5.1 and Huh7-Lunet-CD81 (Lunet-CD81) cells were compared for their responses upon HCV infection. The virus replication level was found slightly higher in Huh7.5.1 cells than that in Lunet-CD81 cells. Viability of Huh7.5.1 cells but not of Lunet-CD81 cells was reduced significantly after HCV infection. Further analysis showed that the cell cycle of infected Huh7.5.1 cells was arrested at G1 phase. The G1/S transition was blocked by HCV infection in Huh7.5.1 cells as shown by the cell cycle synchronization analysis. Genes related to cell cycle regulation was modified by HCV infection and gene interaction analysis in GeneSpring GX in Direct Interactions mode highlighted 31 genes. In conclusion, the responses of those two cell lines were different upon HCV infection. HCV infection blocked G1/S transition and cell cycle progress, thus reduced the cell viability in Huh7.5.1 cells but not in Lunet-CD81 cells. Lunet-CD81 cells might be suitable for long term infection studies of HCV.
文摘This study reports the synthesis and evaluation of a novel furanone-containing antibacterial resin composite. Compres-sive strength (CS) and S. mutans viability were used to evaluate the mechanical strength and antibacterial activity of the composites. With 5% to 30% addition of the furanone derivative, the composite showed no change in CS but a significant antibacterial activity with a 16% - 68% reduction in the S. mutans viability. Further, the antibacterial activity of the modified composite was not affected by human saliva. The aging study implies that the modified composite may have a long-lasting antibacterial function. Within the limitations of this study, it appears that this experimental resin composite may potentially be developed into a clinically attractive dental restorative due to its high mechanical strength and antibacterial function.
文摘A novel antibacterial glass-ionomer cement has been developed. Compressive strength (CS) and S. mutans viability were used to evaluate the mechanical strength and antibacterial activity of the formed cement. Compressive yield strength (YS), modulus (M), diametral tensile strength (DTS) and flexural strength (FS) were also determined. All the formulated antibacterial cements showed a significant antibacterial activity, accompanying with an initial CS reduction. The effect of the synthesized antibacterial polymer loading was significant. Increasing loading from 1% to 20% significantly decreased the S. mutans viability from 3% to 50% and also reduced the initial CS (325 MPa) of the formed cements from 19% to 75%. The cement with 5% antibacterial polymer loading showed 142 MPa, 6.9 GPa, 224 MPa, 52 MPa, and 62 MPa in YS, M, CS, DTS and FS, respectively, as compared to 170, 7.1, 325, 60 and 87 for the experimental cement without antibacterial polymer addition and 141, 6.9, 236, 42 and 53 for Fuji II LC. It was also found that the chlorine-containing antibacterial cement showed better CS values than the bromine-containing cement, with no significant difference in antibacterial activity. The antibacterial cement also showed a similar antibacterial activity to Streptococcus mutans, lactobacillus, Staphylococcus aureus and Staphylococcus epidermidis. The human saliva did not affect the antibacterial activity of the cement. The thirty-day aging study indicates that the cements may have a long-lasting antibacterial function.
基金supported by a grant(03-2010-0240)from the Seoul National University Hospital Research Fund(BSJ)and Yuhan Cooperation(Seoul,Republic of KoreaTBA)
文摘Both genetic and environmental factors are important in the pathogenesis of Parkinson＇s disease. As α-synuclein is a major constituent of Lewy bodies, a pathologic hallmark of Parkinson＇s disease, genetic aspects of α-synuclein is widely studied. However, the influence of dietary factors such as quercetin on α-synuclein was rarely studied. Herein we aimed to study the neuroprotective role of quercetin against various toxins affecting apoptosis, autophagy and aggresome, and the role of quercetin on α-synuclein expression. PC12 cells were pre-treated with quercetin（100, 500, 1,000 μM） and then together with various drugs such as 1-methyl-4-phenylpyridinium（MPP＋; a free radical generator）, 6-hydroxydopamine（6-OHDA; a free radical generator）, ammonium chloride（an autophagy inhibitor）, and nocodazole（an aggresome inhibitor）. Cell viability was determined using a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltertazolium bromide（MTT） assay. Apoptosis was detected by annexin V-fluorescein isothiocyanate and propidium iodide through the use of fluorescence activated cell sorter. α-Synuclein expression was detected by western blot assay and immunohistochemistry. The role of α-synuclein was further studied by knocking out α-synuclein using RNA interference. Cell viability increased at lower concentrations（100 and 500 μM） of quercetin but decreased at higher concentration（1,000 μM）. Quercetin exerted neuroprotective effect against MPP＋, ammonium chloride and nocodazole at 100 μM. MPP＋ induced apoptosis was decreased by 100 μM quercetin. Quercetin treatment increased α-synuclein expression. However, knocking out α-synuclein exerted no significant effect on cell survival. In conclusion, quercetin is neuroprotective against toxic agents via affecting various mechanisms such as apoptosis, autophagy and aggresome. Because α-synuclein expression is increased by quercetin, the role of quercetin as an environmental factor in Parkinson＇s disease pathogenesis needs further investigation.
