Browsing by Author "Huang, Ruijie"
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Item Effect of Green Tea on Streptococcus mutans Metabolic Activity, Planktonic Growth, and Biofilm Activity in the Presence of Nicotine(Office of the Vice Chancellor for Research, 2013-04-05) Gardner, R.; Foltz, J.; Li, Mingyun; Huang, Ruijie; Gregory, Richard L.Streptococcus mutans is the main bacterial cause of dental caries, and it has been proven by previous research that its growth is affected by various concentrations of nicotine and other agents. The amount of S. mutans in the mouth is directly proportional to the number of dental cavities. Studies have shown that smokers have an increased amount of caries, much of which is due to the low concentrations of nicotine the mouth is exposed to. It is known that S. mutans thrives in low-moderate concentrations of nicotine, and that nicotine is a promoting agent for S. mutans. S. mutans has also been proven as a contributor to atherosclerosis, resulting from dental plaque entering the bloodstream. Green Tea is a commonly consumed beverage, which has been known to reduce the number of dental cavities. Previous research has concluded that green tea contains polyphenols, which have antimicrobial effects, including an inhibitory effect on S. mutans. The objective of this research is to observe how green tea affects S. mutans metabolic activity, as well as biofilm and planktonic growth, in the presence of nicotine. The experiments compared S. mutans treated with nicotine concentrations (0-8 mg/ml), and S. mutans treated with a 2.5 g/200 mL concentration of Sencha Jade Reserve Japanese green tea in conjunction with the various nicotine concentrations. The assays were performed in a microtiter plate; the XTT and biofilm assays measured absorbance, and the planktonic assay measured kinetic growth. The experiments conclude that green tea has an inhibitory effect on nicotine-treated S. mutans metabolic activity and planktonic growth, with higher concentrations of green tea inhibiting more effectively. It was also concluded that green tea increases biofilm formation. These conclusions provide evidence of the inhibitory effect green tea has on nicotine-treated S. mutans, and may indicate a way to reduce the incidence of caries and atherosclerosis.Item Effect of nicotine on cariogenic virulence of Streptococcus mutans(Springer, 2016-11) Li, Mingyun; Huang, Ruijie; Zhou, Xuedong; Qiu, Wei; Xu, Xin; Gregory, Richard L.; Department of Biomedical and Applied Sciences, IU School of DentistryNicotine has well-documented effects on the growth and colonization of Streptococcus mutans. This study attempts to investigate the effects of nicotine on pathogenic factors of S. mutans, such as the effect on biofilm formation and viability, expression of pathogenic genes, and metabolites of S. mutans. The results demonstrated that addition of nicotine did not significantly influence the viability of S. mutans cells. The biofilms became increasingly compact as the concentrations of nicotine increased. The expression of virulence genes, such as ldh and phosphotransferase system (PTS)-associated genes, was upregulated, and nlmC was upregulated significantly, while ftf was downregulated. The lactate concentration of S. mutans grown in 1 mg/mL of nicotine was increased up to twofold over either biofilm or planktonic cells grown without nicotine. Changes in the metabolites involved in central carbon metabolism from sucrose indicated that most selected metabolites were detectable and influenced by increased concentrations of nicotine. This study demonstrated that nicotine can influence the pathogenicity of S. mutans and may lead to increased dental caries through the production of more lactate and the upregulation of virulence genes.Item Effect of nicotine on streptococcus mutans(2014-11) Huang, Ruijie; Gregory, Richard L.; Tu, Wanzhu; Windsor, L. Jack; Wu, Christine; Song, FengyuStreptococcus mutans is a key contributor to dental caries. Smokers have increased caries, but the association between tobacco, nicotine, caries and S. mutans growth is little investigated. In the first section, seven S. mutans strains were used for screening. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum biofilm inhibitory concentration (MBIC) were 16 mg/ml (0.1 M), 32 mg/ml (0.2 M), and 16 mg/ml (0.1 M), respectively, for most of the S. mutans strains. Growth of planktonic S. mutans cells was significantly repressed by 2.0-8.0 mg/ml nicotine concentrations. Biofilm formation and metabolic activity of S. mutans was increased in a nicotine-dependent manner up to 16.0 mg/ml. Scanning electron microscopy (SEM) revealed higher nicotine-treated S. mutans had thicker biofilm and more spherical bacterial cells than lower concentrations of nicotine. In the second section, confocal laser scanning microscopy (CLSM) results demonstrated that both biofilm bacterial cell numbers and extracellular polysaccharide (EPS) synthesis were increased by nicotine. Glucosyltransferase (Gtf) and glucan binding protein A (GbpA) protein expression of S. mutans planktonic cells were upregulated, while GbpB protein expression of biofilm cells were downregulated by nicotine. The mRNA expression of those genes were mostly consistent with their protein results. Nicotine was not directly involved in S. mutans LDH activity. However, since it increased the total number of bacterial cells in biofilm; total LDH activity of S. mutans biofilm was increased. In the third section, a PCR-based multiple species cell counting (PCR-MSCC) method was designed to investigate the effect of nicotine on S. mutans in a ten mixed species culture. The absolute S. mutans number in mixed biofilm culture was increased but the percentage of S. mutans in the total number of bacterial cells was not changed. In conclusion, nicotine enhanced biofilm formation and biofilm metabolism of S. mutans, through stimulating S. mutans planktonic cell Gtfs and Gbps expression. This leads to more planktonic cells attaching to dental biofilm. Increased S. mutans cell numbers, in biofilms of single species or ten mixed species, resulted in higher overall LDH activity. More lactic acid may be generated and contribute to caries development in smokers.Item Effect of phototherapy on the metabolism of Streptococcus mutans biofilm based on a colorimetric tetrazolium assay(JST, 2018-06) Gomez, Grace F.; Huang, Ruijie; Eckert, George; Gregory, Richard L.; Biomedical Sciences and Comprehensive Care, School of DentistryThe aim of this in vitro study was to determine the effect of violet-blue light on the metabolic activity of early Streptococcus mutans biofilm, reincubated at 0, 2, and 6 h after 5 min of violet-blue light treatment. S. mutans UA159 biofilm cells were cultured for 12 to 16 h in microtiter plates with Tryptic Soy broth (TSB) or TSB with 1% sucrose (TSBS) and irradiated with violet-blue light for 5 min. After irradiation, the plates were reincubated at 37°C for 0, 2, or 6 h in 5% CO2. Colorimetric tetrazolium salt reduction assay was used to investigate bacterial metabolic activity. Mixed model ANOVA was used to find the difference between the violet-blue light treated and nontreated groups. Bacterial metabolic activity was significantly lower in the violet-blue light group for TSB than in the nontreated group (P < 0.0001) regardless of recovery time. However, the differences between metabolic activity in the treated groups without sucrose decreased over time. For TSBS, metabolic activity was significantly lower with violet-blue light at 0 and 2 h. Violet-blue light inhibited the metabolic activity of S. mutans biofilm cells in the light-treated group. This finding may present a unique treatment method for patients with active caries.Item EFFECT OF TOBACCO-TREATED MG63 OSTEOBLAST ON HUMAN PULP CELLS(Office of the Vice Chancellor for Research, 2012-04-13) Gebreslassie, Seret; Huang, Ruijie; Li, Mingyun; Song, Fengeyu; Gregory, Richard L.Objective: The objective of this study is to determine the effects of to-bacco products on protein concentration and growth of MG63 osteoblasts and the effects of the bacterial cells and culture supernatants on human pulp cells. The study was designed to observe the effects of P.gingivalis grown in four different tobacco solutions such as CSC (cigarette smoked condensate), nicotine (chewing tobacco), and DST (dissolvable smokeless tobacco) strips, and in the media control only without tobacco products. Methods: MG63 os-teoblast was grown in BHI-YE (Bacteria Heart Infusion-Yeast Extract) and hemin-vitamin K. In addition, MG63 osteoblast was grown in BHI-Y-E con-taining nicotine, CSC, and DST. Human pulp cells were grown in media con-taining BGS (Bovine Growth Serum) and washed. The pulp cell cultures will be assayed for cytotoxicity and the supernatants will be assayed for cyto-kines and MMP expression. Results: The protein assays was performed us-ing a microplate spectrophometer and SoftMax Pro 5.2, and we observed that nicotine and DST treated cells had significantly less protein than control cells, however, CSC treated cells had significantly more protein. The undilut-ed control had significantly less protein than the tobacco-treated superna-tants. Conclusion: Based on the previous experiments, we speculate that the additional protein in the undiluted CSC cells and tobacco-treated super-natant may stimulate more effect on human pulp cells than the control, nico-tine or DST treated cells or the control supernatant.Item Effects of artificial honey and epigallocatechin-3-gallate on streptococcus pyogenes(Springer, 2022-08-26) Jiang, Xiaoge; Lin, An; Li, Shijia; Shi, Yangyang; Zhou, Fangjie; Felix Gomez, Grace Gomez; Gregory, Richard L.; Zhang, Chaoliang; Chen, Song; Huang, Ruijie; Oral Pathology, Medicine and Radiology, School of DentistryBackground Streptococcus pyogenes is an important global human pathogen that causes pharyngitis, and antibacterial therapy has become an important part of the overall therapy for pharyngitis. As natural derivatives, honey and green tea are often recommended for patients with pharyngitis in traditional Chinese medicine without experimental theoretical basis on wether the combined effect of honey and green tea on pharyngitis is better than they alone. The aims of this study were to explore the effects of artificial honey (AH) and epigallocatechin-3-gallate (EGCG) on S. pyogenes and elucidate the possible mechanisms, which were investigated using MIC (the minimum inhibitory concentration), FIC (fractional inhibitory concentration) index, growth pattern, biofilm formation and RT-qPCR. Results The MIC of AH on S. pyogenes was 12.5% (v/v) and the MIC of EGCG was 1250 μg/ml. The FIC index of AH and EGCG was 0.5. The planktonic cell growth, growth pattern and biofilm formation assays showed that AH and EGCG mixture had stronger inhibitory effect on S. pyogenes than they alone. RT-qPCR confirmed that the expression of hasA and luxS gene were inhibited by AH and EGCG mixture. Conclusions AH and EGCG mixture can inhibit the planktonic cell growth, biofilm formation and some virulence genes expression of S. pyogenes, better than they alone. The combination of honey and green tea have the potential to treat pharyngitis as natural derivatives, avoiding drug resistance and double infection.Item EFFECTS OF NICOTINE ON QUORUM SENSING IN STREPTOCOCCUS MUTANS(Office of the Vice Chancellor for Research, 2012-04-13) Bikormana, Emmanuel; Huang, Ruijie; Li, Mingyun; Gregory, Richard L.Streptococcus mutans is gram-positive cocci, facultative anaerobic bacterium commonly found in the human oral cavity, and significantly contributes to caries. The quorum sensing system plays an important role in microbial cell-cell interactions that leads to development of dental plaque. S. mutans produces glucosyltransferases together with the glucan binding proteins in order to facilitate the adherence of glucans to the tooth surface, thereby forming biofilms. Moreover, previous studies indicate that in the presence or absence of sucrose, a cell surface protein called antigen I/II plays an important role in the adherence process of S. mutans. There is a relationship between smoking and dental caries, in which the smoking population has a higher incidence of dental caries than a non-smoking population. Nicotine is one of the most important components in tobacco. In this study we investigated the effects of nicotine on quorum sensing in S. mutans. An S. mutans wild type UA159 and its knockout mutants defective in comC, comD and comE were used to investigate planktonic cell growth, the biofilm formation and biofilm metabolism at different concentrations of nicotine (0-32 mg/ml). The effects of nicotine on quorum sensing for S. mutans’ biofilm formation was evaluated using sucrose-dependent and sucrose-independent assays. The results indicate that S. mutans UA159 and its knockout mutants had no substantial differences in planktonic cell growth. In the presence of sucrose, the comC mutant was unable to produce biofilms, whereas the biofilm formation and biofilm metabolism of the comD and comE mutants were enhanced with increased nicotine concentration as with UA159 up to 8 mg/mL of nicotine. However, in the absence of sucrose, it was observed that the ComC mutant formed biofilms relatively similar to UA159. Biofilm formation in the comD and comE mutants was also enhanced with the increase of nicotine concentration up to 4 and 2 mg/mL, respectively. The results suggest that nicotine enhances the adherence process in S. mutans by antigen I/II through the comDE signaling pathway. However, the fact that the comC mutant produced biofilm in the absence of sucrose, but not in the presence of sucrose, indicates that the activity of antigen I/II is activated through different cell-cell signaling pathways depending on the amount of sucrose present.Item Evaluating hop extract concentrations found in commercial beer to inhibit Streptococcus mutans biofilm formation(Wiley, 2022) Gregory, Eric R.; Bakhaider, Renad F.; Gomez, Grace F.; Huang, Ruijie; Moser, Elizabeth A.S.; Gregory, Richard L.; Biomedical Sciences and Comprehensive Care, School of DentistryAims: The purpose of this study was to compare the effect of hop extracts with diverse β-acid concentrations on Streptococcus mutans biofilm formation. Methods and results: Ten different hop extracts, with α-acid concentrations similar to those found in commercial beer products and β-acid concentrations ranging from 2.6 to 8.1%, were added to distilled water to make standardized concentrations. S. mutans isolates were treated with hop extract dilutions varying from 1:2 to 1:256. The minimum inhibitory, minimum bactericidal and minimum biofilm inhibitory concentrations were determined and the optical density was evaluated. Live/dead staining confirmed the bactericidal effects. Biofilm formation of several strains of S. mutans was significantly inhibited by hop extract dilutions of 1:2, 1:4, 1:8, 1:16 and 1:32. Strong negative correlations were observed between α- and β-acid concentrations of the hop extracts and S. mutans total growth and biofilm formation. Conclusions: The use of hop extracts prepared similarly to commercial beer decreased S. mutans biofilm formation. Significance and impact of the study: The inclusion of hops in the commercial beer products may provide beneficial health effects. Further studies are warranted to determine an effect in vivo on the development of dental caries.Item Evaluation of selected properties of a new root repair cement containing surface pre-reacted glass ionomer fillers(Springer, 2016) Yassen, Ghaeth H.; Huang, Ruijie; Al-Zain, Afnan; Yoshida, Takamitsu; Gregory, Richard L.; Platt, Jeffrey A.; Department of Biomedical and Applied Sciences, IU School of DentistryObjective This study evaluated selected properties of a prototype root repair cement containing surface pre-reacted glass ionomer fillers (S-PRG) in comparison to mineral trioxide aggregate (MTA) and intermediate restorative material (IRM). Materials and methods The antibacterial effect of S-PRG, MTA, and IRM cements was tested against Porphyromonas gingivalis and Enterococcus faecalis after 1 and 3 days of aging of the cements. The set cements were immersed in distilled water for 4 h to 28 days, and ion-releasing ability was evaluated. Initial and final setting times of all cements were evaluated using Gilmore needles. The push-out bond strength between radicular dentin and all cements was tested at different levels of the roots. Results S-PRG and IRM cements, but not MTA cement, demonstrated significant antibacterial effect against P. gingivalis. All types of cements exhibited significant antibacterial effect against E. faecalis without being able to eliminate the bacterium. S-PRG cement provided continuous release of fluoride, strontium, boron, sodium, aluminum, and zinc throughout all tested time points. Both initial and final setting times were significantly shorter for S-PRG and IRM cements in comparison to MTA. The push-out bond strength was significantly lower for S-PRG cement in comparison to MTA and IRM at coronal and middle levels of the roots. Conclusions S-PRG cement demonstrated significant antibacterial effects against endodontic pathogens, multiple ion-releasing ability, relatively short setting time, and low bonding strength. Clinical relevance S-PRG cement can be used as a one-visit root repair material with promising antibacterial properties and ion-releasing capacity.Item In Vitro Effects of Sports and Energy Drinks on Streptococcus mutans Biofilm Formation and Metabolic Activity(AAPD, 2017) Vinson, LaQuia A.; Goodlett, Amy K.; Huang, Ruijie; Eckert, George J.; Gregory, Richard L.; Pediatric Dentistry, School of DentistryPurpose: Sports and energy drinks are being increasingly consumed and contain large amounts of sugars, which are known to increase Streptococcus mutans biofilm formation and metabolic activity. The purpose of this in vitro study was to investigate the effects of sports and energy drinks on S. mutans biofilm formation and metabolic activity. Methods: S. mutans UA159 was cultured with and without a dilution (1:3 ratio) of a variety of sports and energy drinks in bacterial media for 24 hours. The biofilm was washed, fixed, and stained. Biofilm growth was evaluated by reading absorbance of the crystal violet. Biofilm metabolic activity was measured by the biofilm-reducing XTT to a water-soluble orange compound. Results: Gatorade Protein Recovery Shake and Starbucks Doubleshot Espresso Energy were found to significantly increase biofilm (30-fold and 22-fold, respectively) and metabolic activity (2-fold and 3-fold, respectively). However, most of the remaining drinks significantly inhibited biofilm growth and metabolic activity. Conclusions: Several sports and energy drinks, with sugars or sugar substitutes as their main ingredients inhibited S. mutans biofilm formation. Among the drinks evaluated, Gatorade Protein Recovery Chocolate Shake and Starbucks Doubleshot Energy appear to have cariogenic potential since they increased the biofilm formation and metabolic activity of S. mutans.