Publications by authors named "Chaminda Jayampath Seneviratne"

32 Publications

Role of the oral microbiome, metabolic pathways, and novel diagnostic tools in intra-oral halitosis: a comprehensive update.

Crit Rev Microbiol 2021 Mar 3:1-17. Epub 2021 Mar 3.

Oral Health ACP, Duke NUS Medical School, Singapore, Singapore.

Halitosis or oral malodor is one of the most common reasons for the patients' visit to the dental clinic, ranking behind only dental caries and periodontitis. In the present times, where social and professional communications are becoming unavoidable, halitosis has become a concern of growing importance. Oral malodor mostly develops due to the putrefaction of substrates by the indigenous bacterial populations. Although culture-based studies have provided adequate information on halitosis, the high throughput omics technologies have amplified the resolution at which oral microbial community can be examined and has led to the detection of a broader range of taxa associated with intra-oral halitosis (IOH). These microorganisms are regulated by the interactions of their ecological processes. Thus to develop effective treatment strategies, it is important to understand the microbial basis of halitosis. In the current review, we provide an update on IOH in context to the role of the oral microbiome, metabolic pathways involved, and novel diagnostic tools, including breathomics. Understanding oral microbiota associated with halitosis from a broader ecological perspective can provide novel insights into one's oral and systemic health. Such information can pave the way for the emergence of diagnostic tools that can revolutionize the early detection of halitosis and various associated medical conditions.
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http://dx.doi.org/10.1080/1040841X.2021.1888867DOI Listing
March 2021

Casein phosphopeptide-amorphous calcium phosphate fluoride treatment enriches the symbiotic dental plaque microbiome in children.

J Dent 2021 Mar 12;106:103582. Epub 2021 Jan 12.

Singapore Oral Microbiomics Initiative, National Dental Research Institute Singapore (NDRIS), National Dental Centre Singapore, Oral Health ACP, Duke NUS Medical School, Singapore. Electronic address:

Objectives: The dysbiotic oral microbiome plays a key role in the pathogenesis of caries in children. Topical application of casein phosphopeptide-amorphous calcium phosphate containing fluoride (CPP-ACP/F) is an effective treatment modality for children with caries (CC). Hitherto the mechanism by which CPP-ACP/F modules the oral microbiome in CC has not been investigated. The study aimed to examine the CPP-ACP/F effect on the dental plaque microbiome of children group with caries.

Methods: This preliminary prospective clinical cohort included 10 children with caries. The children received topical fluoride CPP-ACP/F once-a-week for one month. Plaque samples were collected before and after treatment and subjected to 16S rDNA-based next-generation-sequencing. Microbial composition, diversity and functional roles were analyzed in comparison to the clinical characteristics of cohort using standard bioinformatics tools.

Results: CPP-ACP/F treatment modulated dysbiotic oral microbiome towards healthier community as the higher proportion of Proteobacteria and certain microbial protective species were enriched following CPP-ACP/F treatment. Despite overall uniformity of community structure in children with caries between the groups, some bacterial species were differentially represented in a statistically significant manner between pre- and post- treatments. Three bacterial species were found to be predictive of strongly sensitive to the CPP-ACP/F treatment, marked by decreased abundance of Lautropia mirabalis and increased abundance of Gemella haemolysans and Schwartzia succinivorans.

Conclusion: Within the limits of the current study, it could be concluded that the CPP-ACP/F varnish treatment modulated the microbial composition of the dental plaque microbiome towards symbiosis. These symbiotic changes may demonstrate the potential clinical significance of CPP-ACP/F varnish treatment.
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http://dx.doi.org/10.1016/j.jdent.2021.103582DOI Listing
March 2021

Persistent inhibition of Candida albicans biofilm and hyphae growth on titanium by graphene nanocoating.

Dent Mater 2021 Feb 25;37(2):370-377. Epub 2020 Dec 25.

Faculty of Dentistry, National University of Singapore, 9 Lower Kent Ridge Road, Singapore; Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore; NUS Craniofacial Research and Innovation Center, National University of Singapore, Singapore. Electronic address:

Objectives: Candida albicanscolonizes biomaterial surfaces and are highly resistant to therapeutics. Graphene nanocoating on titanium compromises initial biofilm formation. However, its sustained antibiofilm potential is unknown. The objective of this study was to investigate the potential of graphene nanocoating to decrease long-term fungal biofilm development and hyphae growth on titanium.

Methods: Graphene nanocoating was deposited twice (TiGD) or five times (TiGV) on grade 4 titanium with vacuum assisted technique and characterized with Raman spectroscopy and atomic force microscope. The biofilm formation and hyphae growth of C. albicans was monitored for seven days by CFU, XTT, confocal, mean cell density and scanning electronic microscopy (SEM). Uncoated titanium was the Control. All tests had three independent biological samples and were performed in independent triplicates. Data was analyzed with one- or two-way ANOVA and Tukey's HSD (α = 0.05).

Results: Both TiGD and TiGV presented less biofilms at all times points compared with Control. The confocal and SEM images revealed few adhered cells on graphene coated samples, absence of hyphae and no features of a mature biofilm architecture. The increase in number of layers of graphene nanocoating did not improve its antibiofilm potential.

Significance: The graphene nanocoating exerted a long-term persistent inhibitory effect on the biofilm formation on titanium. The fewer cells that were able to attach on graphene coated titanium were scattered and unable to form a mature biofilm with hyphae elements. The findings open opportunities to prevent microbial attachment and proliferation on implantable materials without the use of antibiotics.
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http://dx.doi.org/10.1016/j.dental.2020.11.028DOI Listing
February 2021

A Risk-Based Approach to the COVID-19 Pandemic: The Experience in National Dental Centre Singapore.

Front Med (Lausanne) 2020 20;7:562728. Epub 2020 Nov 20.

Oral Health Academic Clinical Programme, Duke-NUS Medical School, Singapore, Singapore.

The emergence of a highly infectious coronavirus strain, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to a major global public health emergency. The increasing number of infected cases and fatalities worldwide forced several countries into lockdown in a bid to control virus transmission. The practice of dentistry is considered high-risk due to the generation of aerosols associated with most dental procedures, and healthcare professionals must take appropriate precautions whilst working in this challenging environment. This review aims to provide an overview on transmission routes and shares a risk-based approach to coronavirus disease 2019 (COVID-19) in a specialty tertiary center. Risk assessment and mitigation focussed on staff and patient safety, adopting a wide safety margin, and responding dynamically to the level of risk at the workplace. As the severity of the pandemic depends on many still-unknown factors and shows little sign of abating, the routine practice of dentistry will continue to be disrupted in the near future. We describe a color-coded framework to maximize safety and to minimize disease spread. Areas covered include healthcare team management, personal protective equipment, clinical work, and dental education. Guidelines in each category change with the corresponding severity of the situation, and we believe it will be useful for the safer practice of dentistry in this current climate and can be modified for future similar disease outbreaks.
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http://dx.doi.org/10.3389/fmed.2020.562728DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7714928PMC
November 2020

The Role of Dentists in COVID-19 Is Beyond Dentistry: Voluntary Medical Engagements and Future Preparedness.

Front Med (Lausanne) 2020 6;7:566. Epub 2020 Oct 6.

National Dental Research Institute Singapore, National Dental Centre Singapore, Singapore, Singapore.

The emergence of the highly infectious novel coronavirus SARS-CoV-2 has led to a global COVID-19 pandemic. Since the outbreak of COVID-19, worldwide healthcare systems have been severely challenged. The rapid and explosive surge of positive cases has significantly increased the demand for medical care. Herein we provide a perspective on the role dentists can play in voluntary medical assistance and future preparedness for a similar pandemic. Though dentists and physicians have different scopes of practice, their trainings share many similarities. Hence, dental professionals, with their knowledge of basic human science and sterile surgical techniques, are an invaluable resource in the COVID-19 pandemic response. Overall, it is commendable that many dentists have risen to the challenge in the fight against COVID-19. For example, in Singapore, National Dental Centre Singapore (NDCS) deployed dental clinicians as well as volunteers from research laboratories to screen for suspected cases, provide consultations as well as conduct swabbing operations. Dental practice will be considerably changed in the post-COVID-19 era. There is a greater need to have refresher courses for practicing dentists on new infection control strategies. Moreover, the curriculum in dental schools should be expanded to include competencies in pandemic and disaster relief. In addition, voluntary medical work should be made a part of the community dentistry curriculum. This volunteerism will leave a positive impact on developing the careers of young dentists. Hence, the contribution of dentists beyond dental practice in this pandemic situation will be appreciated by future generations.
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http://dx.doi.org/10.3389/fmed.2020.00566DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7574679PMC
October 2020

The Proteome of Community Living Is Differentially Modulated by the Morphologic and Structural Features of the Bacterial Cohabitants.

Microorganisms 2020 Oct 7;8(10). Epub 2020 Oct 7.

National Dental Research Institute Singapore (NDRIS), National Dental Centre Singapore, Singapore 168938, Singapore.

is a commensal polymorphic and opportunistic fungus, which usually resides as a small community in the oral cavities of a majority of humans. The latter eco-system presents this yeast varied opportunities for mutualistic interactions with other cohabitant oral bacteria, that synergizes its persistence and pathogenicity. Collectively, these communities live within complex plaque biofilms which may adversely affect the oral health and increase the proclivity for oral candidiasis. The proteome of such oral biofilms with myriad interkingdom interactions are largely underexplored. Herein, we employed limma differential expression analysis, and cluster analysis to explore the proteomic interactions of biofilms with nine different common oral bacterial species, , , , , , , , , and . Interestingly, upon exposure of biofilms to the foregoing heat-killed bacteria, the proteomes of the fungus associated with cellular respiration, translation, oxidoreductase activity, and ligase activity were significantly altered. Subsequent differential expression and cluster analysis revealed the subtle, yet significant alterations in the proteome, particularly on exposure to bacteria with dissimilar cell morphologies, and Gram staining characteristics.
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http://dx.doi.org/10.3390/microorganisms8101541DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7601143PMC
October 2020

Inhibitory effects of xylitol and sorbitol on Streptococcus mutans and Candida albicans biofilms are repressed by the presence of sucrose.

Arch Oral Biol 2020 Nov 29;119:104886. Epub 2020 Aug 29.

Singapore Oral Microbiomics Initiative, National Dental Research Institute Singapore (NDRIS), National Dental Centre Singapore, SingHealth Duke NUS Medical School, 5 Second Hospital Avenue, Singapore. Electronic address:

Objective: Among the preventive and therapeutic options available for dental caries, sugar alcohols (xylitol and sorbitol) have been widely promoted as oral healthcare products due to its perceived anticariogenic effect. However, the therapeutic efficacy of these sugar alcohols against Streptococcus mutans and Candida albicans in a sucrose supplemented environment, as found in disease-prone conditions in the oral cavity, has not been adequately investigated.

Methods: Single and mixed-species biofilm formation was evaluated in medium with different concentrations of xylitol, sorbitol with or without sucrose supplementation. Biofilm quantification methods such as crystal violet assay, XTT assay, CFU counting complemented with confocal and electron microscopic techniques were used.

Results: Under sucrose-free conditions, xylitol and sorbitol demonstrated a significant dose-dependent inhibitory effect on S. mutans biofilms, whereas inhibitory effect on C. albicans biofilm was weak. The presence of 1 % sucrose in the environment diminished the inhibitory effect of both xylitol and sorbitol on S. mutans and C. albicans mono-species biofilms. Sucrose supplementation on pre-formed S. mutans biofilms also reduced the inhibitory effect of xylitol. Xylitol and sorbitol presence reduced mixed-species biofilm formation and altered the biofilm architecture and glucan production. However, sucrose supplementation reduced the inhibitory effect of sugar alcohols and enhanced the mixed-species biofilm formation.

Conclusions: Xylitol and sorbitol exerts an inhibitory effect on S. mutans and C. albicans biofilm formation and this inhibitory effect is repressed by the presence of sucrose.
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http://dx.doi.org/10.1016/j.archoralbio.2020.104886DOI Listing
November 2020

Lactobacillus Plantarum 108 Inhibits Streptococcus mutans and Candida albicans Mixed-Species Biofilm Formation.

Antibiotics (Basel) 2020 Aug 4;9(8). Epub 2020 Aug 4.

Singapore Oral Microbiomics Initiative, National Dental Research Institute Singapore (NDRIS), National Dental Centre Singapore, SingHealth Duke NUS Medical School, 5 Second Hospital Avenue, Singapore 168938, Singapore.

is the principal biofilm forming oral pathogen associated with dental caries. Studies have shown that , a commensal oral fungus is capable of forming pathogenic mixed-species biofilms with The treatment of bacterial and fungal infections using conventional antimicrobial agents has become challenging due to the antimicrobial resistance of the biofilm mode of growth. The present study aimed to evaluate the efficacy of secretory components of , a potentially promising probiotic strain, against and single and mixed-species biofilms. supernatant inhibited and single-species biofilms as shown by XTT reduction assay, crystal violet assay, and colony forming units counting. The probiotic supernatant significantly inhibited the mixed-species biofilm formation. The pre-formed mixed-species biofilms were also successfully reduced. Confocal microscopy showed poorly developed biofilm architecture in the probiotic supernatant treated biofilms. Moreover, the expression of genes associated with glucosyltransferase activity and hyphal specific genes ( and ) were down-regulated in the presence of the probiotic supernatant. Altogether, the data demonstrated the capacity of supernatant to inhibit the and mixed-species biofilms. Herein, we provide a new insight on the potential of probiotic-based strategies to prevent bacterial-fungal mixed-species biofilms associated with dental caries.
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http://dx.doi.org/10.3390/antibiotics9080478DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7459986PMC
August 2020

Oral microbiome-systemic link studies: perspectives on current limitations and future artificial intelligence-based approaches.

Crit Rev Microbiol 2020 May 21;46(3):288-299. Epub 2020 May 21.

Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam, University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.

In the past decade, there has been a tremendous increase in studies on the link between oral microbiome and systemic diseases. However, variations in study design and confounding variables across studies often lead to inconsistent observations. In this narrative review, we have discussed the potential influence of study design and confounding variables on the current sequencing-based oral microbiome-systemic disease link studies. The current limitations of oral microbiome-systemic link studies on type 2 diabetes mellitus, rheumatoid arthritis, pregnancy, atherosclerosis, and pancreatic cancer are discussed in this review, followed by our perspective on how artificial intelligence (AI), particularly machine learning and deep learning approaches, can be employed for predicting systemic disease and host metadata from the oral microbiome. The application of AI for predicting systemic disease as well as host metadata requires the establishment of a global database repository with microbiome sequences and annotated host metadata. However, this task requires collective efforts from researchers working in the field of oral microbiome to establish more comprehensive datasets with appropriate host metadata. Development of AI-based models by incorporating consistent host metadata will allow prediction of systemic diseases with higher accuracies, bringing considerable clinical benefits.
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http://dx.doi.org/10.1080/1040841X.2020.1766414DOI Listing
May 2020

Proteomics Analysis of Candida albicans dnm1 Haploid Mutant Unraveled the Association between Mitochondrial Fission and Antifungal Susceptibility.

Proteomics 2020 01 18;20(1):e1900240. Epub 2019 Dec 18.

National Dental Research Institute Singapore, Singhealth Duke NUS, Singapore, 5 Second Hospital Ave, Singapore, 168938.

Candida albicans is a major fungal pathogen, accounting for approximately 15% of healthcare infections with associated mortality as high as 40% in the case of systemic candidiasis. Antifungal agents for C. albicans infections are limited, and rising resistance is an inevitable problem. Therefore, understanding the mechanism behind antifungal responses is among the top research focuses in combating Candida infections. Herein, the recently developed C. albicans haploid model is employed to examine the association between mitochondrial fission, regulated by Dnm1, and the pathogen's response to antifungals. Proteomic analysis of dnm1Δ and its wild-type haploid parent, GZY803, reveal changes in proteins associated with mitochondrial structures and functions, cell wall, and plasma membrane. Antifungal susceptibility testing revealed that dnm1Δ is more susceptible to SM21, a novel antifungal, than GZY803. Analyses of reactive oxygen species release, antioxidant response, lipid peroxidation, and membrane damages uncover an association between dnm1Δ and the susceptibility to SM21. Dynasore-induced mitochondrial inhibition in SC5314 diploids corroborate the findings. Interestingly, Dynasore-primed SC5314 cultures exhibit increased susceptibility to all antifungals tested. These data suggest an important contribution of mitochondrial fission in antifungal susceptibility of C. albicans. Hence, mitochondrial fission can be a potential target for combined therapy in anti-C. albicans treatment.
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http://dx.doi.org/10.1002/pmic.201900240DOI Listing
January 2020

Periodontal Commensals and Pathogens Differentially Modulate Immuno-Inflammatory Response in Human Oral Keratinocytes.

Chin J Dent Res 2019 ;22(2):105-112

Objective: To investigate the immunoinflammatory response in the crosstalk of human oral keratinocytes (HOKs) with selected periodontal commensals and pathogens.

Methods: Four representative viable oral bacteria, including periodontal commensals (Streptococcus mutans, Sm; and Actinomyces israelii, Ai) and pathogens (Aggregatibacter actinomycetemcomitans, Aa; and Porphyromonas gingivalis, Pg), were selected. A viable bacteria-HOKs interactive model was tested under various conditions of oxygen, antibiotics, duration and multiplicity of infection (MOI). The expression of IL-6 and IL-8 in HOKs was assessed by real-time qPCR and ELISA.

Results: An MOI of 1 was determined to be the appropriate ratio of bacteria and HOKs with substantial amounts of viable bacterial cells and HOKs in an antibiotic-free medium under aerobic conditions for 2 h. Sm and Pg significantly upregulated the expression of IL-6 and IL-8 (P < 0.05), while Ai and Aa could not induce significant levels of these cytokines with reference to the control.

Conclusion: Within the limitations of this study, the current findings suggest that periodontal commensals and pathogens may differentially modulate immunoinflammatory response in human oral keratinocytes.
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http://dx.doi.org/10.3290/j.cjdr.a42514DOI Listing
October 2019

Machine learning and its potential applications to the genomic study of head and neck cancer-A systematic review.

J Oral Pathol Med 2019 Oct 21;48(9):773-779. Epub 2019 Apr 21.

Department of Oral & Maxillofacial Surgery, Queen Alexandra Hospital, Portsmouth, UK.

Background: Machine learning (ML) is powerful tool that can identify and classify patterns from large quantities of cancer genomic data that may lead to the discovery of new biomarkers, new drug targets, and a better understanding of important cancer genes. The aim of this systematic review was to evaluate the existing literature and assess the application of machine learning of genomic data in head and neck cancer (HNC).

Materials And Methods: The addressed focused question was "Does machine learning of genomic data play a role in prognostic prediction of HNC?" PubMed, EMBASE, Scopus, Web of Science, and gray literature from January 1990 up to and including May 2018 were searched. Two independent reviewers performed the study selection according to eligibility criteria.

Results: A total of seven studies that met the eligibility criteria were included. The majority of studies were cohort studies, one a case-control study and one a randomized controlled trial. Two studies each evaluated oral cancer and laryngeal cancer, while other one study each evaluated nasopharyngeal cancer and oropharyngeal cancer. The majority of studies employed support vector machine (SVM) as a ML technique. Among the included studies, the accuracy rates for ML techniques ranged from 56.7% to 99.4%.

Conclusion: Our findings showed that ML techniques for the analysis of genomic data can play a role in the prognostic prediction of HNC.
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http://dx.doi.org/10.1111/jop.12854DOI Listing
October 2019

Hydrophobicity of graphene as a driving force for inhibiting biofilm formation of pathogenic bacteria and fungi.

Dent Mater 2019 03 21;35(3):403-413. Epub 2019 Jan 21.

Faculty of Dentistry, National University of Singapore, Singapore; Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore. Electronic address:

Objective: To evaluate the surface and wettability characteristics and the microbial biofilm interaction of graphene coating on titanium.

Methods: Graphene was deposited on titanium (Control) via a liquid-free technique. The transfer was performed once (TiGS), repeated two (TiGD) and five times (TiGV) and characterized by AFM (n=10), Raman spectroscopy (n=10), contact angle and SFE (n=5). Biofilm formation (n=3) to Streptococcus mutans, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans was evaluated after 24h by CV assay, CFU, XTT and confocal microscopy. Statistics were performed by one-way Anova, Tukey's tests and Pearson's correlation analysis at a pre-set significance level of 5 %.

Results: Raman mappings revealed coverage yield of 82 % for TiGS and ≥99 % for TiGD and TiGV. Both TiGD and TiGV presented FWHM>44cm and I/I ratio<0.12, indicating multiple graphene layers and occlusion of defects. The contact angle was significantly higher for TiGD and TiGV (110° and 117°) comparing to the Control (70°). The SFE was lower for TiGD (13.8mN/m) and TiGV (12.1mN/m) comparing to Control (38.3mN/m). TiGD was selected for biofilm assays and exhibited significant reduction in biofilm formation for all microorganisms compared to Control. There were statistical correlations between the high contact angle and low SFE of TiGD and decreased biofilm formation.

Significance: TiGD presented high quality and coverage and decreased biofilm formation for all species. The increased hydrophobicity of graphene films was correlated with the decreased biofilm formation for various species.
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http://dx.doi.org/10.1016/j.dental.2018.09.016DOI Listing
March 2019

Keystone Species in Pregnancy Gingivitis: A Snapshot of Oral Microbiome During Pregnancy and Postpartum Period.

Front Microbiol 2018 9;9:2360. Epub 2018 Oct 9.

Discipline of Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore, Singapore.

It is well known that pregnancy is under the constant influence of hormonal, metabolic and immunological factors and this may impact the oral microbiota toward pregnancy gingivitis. However, it is still not clear how the oral microbial dysbiosis can modulate oral diseases as oral microbiome during pregnancy is very poorly characterized. In addition, the recent revelation that placental microbiome is akin to oral microbiome further potentiates the importance of oral dysbiosis in adverse pregnancy outcomes. Hence, leveraging on the 16S rRNA gene sequencing technology, we present a snapshot of the variations in the oral microbial composition with the progression of pregnancy and in the postpartum period and its association with pregnancy gingivitis. Despite the stability of oral microbial diversity during pregnancy and postpartum period, we observed that the microbiome makes a pathogenic shift during pregnancy and reverts back to a healthy microbiome during the postpartum period. Co-occurrence network analysis provided a mechanistic explanation of the pathogenicity of the microbiome during pregnancy and predicted taxa at hubs of interaction. Targeting the taxa which form the ecological guilds in the underlying microbiome would help to modulate the microbial pathogenicity during pregnancy, thereby alleviating risk for oral diseases and adverse pregnancy outcomes. Our study has also uncovered the possibility of novel species in subgingival plaque and saliva as the key players in the causation of pregnancy gingivitis. The keystone species hold the potential to open up avenues for designing microbiome modulation strategies to improve host health during pregnancy.
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http://dx.doi.org/10.3389/fmicb.2018.02360DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6189292PMC
October 2018

Oral Health in Pregnant Chinese Women in Singapore: A Call to Go beyond the Traditional Clinical Care.

Healthcare (Basel) 2018 Jul 9;6(3). Epub 2018 Jul 9.

Discipline of Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore 119083, Singapore.

Objective: To examine the correlations among oral health knowledge, attitude, practices and oral disease among pregnant Chinese women in Singapore. : A descriptive correlational study was conducted in pregnant Chinese women in Singapore. A questionnaire was used to collect data of oral health knowledge, attitude and practices. Plaque index scores were used to assess the oral health of subjects. : A total of 82 pregnant women participated in the study, out of whom 38% showed adequate oral health knowledge, nearly half of them achieved adequate and oral health attitude and practice scores while 34% had good Plaque index scores. The lower income group had higher experience of self-reported dental problems during pregnancy than those in the higher income group ( = 0.03). There were significant positive correlations between scores of oral health practice, attitude and oral health knowledge levels. The plaque index scores negatively correlated with the oral health practice scores ( = 0.02). : Our findings provided evidence that oral health knowledge, attitude and practices among Chinese pregnant women were not optimal which implies the importance of promoting their oral health during pregnancy through the improvement of knowledge and attitudes. This would facilitate formulation and implementation of appropriate oral health promotion policies.
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http://dx.doi.org/10.3390/healthcare6030077DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6163358PMC
July 2018

Quantitative Proteomics of Strong and Weak Biofilm Formers of Reveals Novel Regulators of Biofilm Formation.

Mol Cell Proteomics 2018 04 22;17(4):643-654. Epub 2018 Jan 22.

From the Oral Sciences, Faculty of Dentistry, National University of Singapore;

is a bacterial pathogen associated with both endodontic and systemic infections. The biofilm formation ability of plays a key role in its virulence and drug resistance attributes. The formation of biofilms on implanted medical devices often results in treatment failure. In the present study, we report protein markers associated with the biofilm formation ability of using iTRAQ-based quantitative proteomics approach. In order to elucidate the biofilm-associated protein markers, we investigated the proteome of strong and weak biofilm-forming clinical isolates in comparison with standard American Type Culture Collection (ATCC) control strains. Comparison of strong and weak biofilm-forming clinical isolates with ATCC control strains showed that proteins associated with shikimate kinase pathway and sulfate transport were up-regulated in the strong biofilm former, while proteins associated with secondary metabolites, cofactor biosynthesis, and tetrahydrofolate biosynthesis were down-regulated. In the weak biofilm former, proteins associated with nucleoside and nucleotide biosynthesis were up-regulated, whereas proteins associated with sulfate and sugar transport were down-regulated. Further pathway and gene ontology analyses revealed that the major differences in biofilm formation arise from differences in metabolic activity levels of the strong and weak biofilm formers, with higher levels of metabolic activity observed in the weak biofilm former. The differences in metabolic activity could therefore be a major determinant of the biofilm ability of The new markers identified from this study can be further characterized in order to understand their exact role in biofilm formation ability. This, in turn, can lead to numerous therapeutic benefits in the treatment of this oral and systemic pathogen. The data has been deposited to the ProteomeXchange with identifier PXD006542.
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http://dx.doi.org/10.1074/mcp.RA117.000461DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5880108PMC
April 2018

Comparative Ploidy Proteomics of Candida albicans Biofilms Unraveled the Role of the AHP1 Gene in the Biofilm Persistence Against Amphotericin B.

Mol Cell Proteomics 2016 11 19;15(11):3488-3500. Epub 2016 Sep 19.

From the ‡Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore 119083,

Candida albicans is a major fungal pathogen causing lethal infections in immunocompromised patients. C. albicans forms antifungal tolerant biofilms contributing significantly to therapeutic failure. The recently established haploid C. albicans biofilm model provides a new toolbox to uncover the mechanism governing the higher antifungal tolerance of biofilms. Here, we comprehensively examined the proteomics and antifungal susceptibility of standard diploid (SC5314 and BWP17) and stable haploid (GZY792 and GZY803) strains of C. albicans biofilms. Subsequent downstream analyses identified alkyl hydroperoxide reductase 1 (AHP1) as a critical determinant of C. albicans biofilm's tolerance of amphotericin B. At 32 μg/ml of amphotericin B, GZY803 haploid biofilms showed 0.1% of persister population as compared with 1% of the diploid biofilms. AHP1 expression was found to be lower in GZY803 biofilms, and AHP1 overexpression in GZY803 restored the percentage of persister population. Consistently, deleting AHP1 in the diploid strain BWP17 caused a similar increase in amphotericin B susceptibility. AHP1 expression was also positively correlated with the antioxidant potential. Furthermore, C. albicans ira2Δ/Δ biofilms were susceptible to amphotericin B and had a diminished antioxidant capacity. Interestingly, AHP1 overexpression in the ira2Δ/Δ strain restored the antioxidant potential and enhanced the persister population against amphotericin B, and shutting down the AHP1 expression in ira2Δ/Δ biofilms reversed the effect. In conclusion, we provide evidence that the AHP1 gene critically determines the amphotericin B tolerance of C. albicans biofilms possibly by maintaining the persisters' antioxidant capacity. This finding will open up new avenues for developing therapies targeting the persister population of C. albicans biofilms. The mass spectrometry proteomics data are available via ProteomeXchange with identifier PXD004274.
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http://dx.doi.org/10.1074/mcp.M116.061523DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5098045PMC
November 2016

Innate Immune Response of Human Embryonic Stem Cell-Derived Fibroblasts and Mesenchymal Stem Cells to Periodontopathogens.

Stem Cells Int 2016 25;2016:8905365. Epub 2016 Aug 25.

Discipline of Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore; NUS Graduate School for Integrative Sciences and Engineering, Singapore; Tissue Engineering Program, Life Sciences Institute, National University of Singapore, Singapore.

Periodontitis involves complex interplay of bacteria and host immune response resulting in destruction of supporting tissues of the tooth. Toll-like receptors (TLRs) play a role in recognizing microbial pathogens and eliciting an innate immune response. Recently, the potential application of multipotent stem cells and pluripotent stem cells including human embryonic stem cells (hESCs) in periodontal regenerative therapy has been proposed. However, little is known about the impact of periodontopathogens on hESC-derived progenies. This study investigates the effects of heat-killed periodontopathogens, namely, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, on TLR and cytokine expression profile of hESC-derived progenies, namely, fibroblasts (hESC-Fib) and mesenchymal stem cells (hESC-MSCs). Additionally, the serotype-dependent effect of A. actinomycetemcomitans on hESC-derived progenies was explored. Both hESC-Fib and hESC-MSCs constitutively expressed TLR-2 and TLR-4. hESC-Fib upon exposure to periodontopathogens displayed upregulation of TLRs and release of cytokines (IL-1β, IL-6, and IL-8). In contrast, hESC-MSCs were largely nonresponsive to bacterial challenge, especially in terms of cytokine production. Further, exposure of hESC-Fib to A. actinomycetemcomitans serotype c was associated with higher IL-8 production than serotype b. In contrast, the hESC-MSCs displayed no serotype-dependent response. Differential response of the two hESC progenies implies a phenotype-dependent response to periodontopathogens and supports the concept of immunomodulatory properties of MSCs.
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http://dx.doi.org/10.1155/2016/8905365DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5014959PMC
September 2016

Synergistic Antibacterial Effects of Nanoparticles Encapsulated with Scutellaria baicalensis and Pure Chlorhexidine on Oral Bacterial Biofilms.

Nanomaterials (Basel) 2016 Apr 7;6(4). Epub 2016 Apr 7.

Faculty of Dentistry, The University of Hong Kong, 34 Hospital Road, Hong Kong, China.

(SB) is a traditional Chinese medicine for treating infectious and inflammatory diseases. Our recent study shows potent antibacterial effects of nanoparticle-encapsulated chlorhexidine (Nano-CHX). Herein, we explored the synergistic effects of the nanoparticle-encapsulated SB (Nano-SB) and Nano-CHX on oral bacterial biofilms. Loading efficiency of Nano-SB was determined by thermogravimetric analysis, and its releasing profile was assessed by high-performance liquid chromatographyusing baicalin (a flavonoid compound of SB) as the marker. The mucosal diffusion assay on Nano-SB was undertaken in a porcine model. The antibacterial effects of the mixed nanoparticles (Nano-MIX) of Nano-SB and Nano-CHX at 9:1 (/) ratio were analyzed in both planktonic and biofilm modes of representative oral bacteria. The Nano-MIX was effective on the mono-species biofilms of () , , () , and () (MIC 50 μg/mL) at 24 h, and exhibited an enhanced effect against the multi-species biofilms such as , , , and () (MIC 12.5 μg/mL) at 24 h that was supported by the findings of both scanning electron microscopy (SEM) and confocal scanning laser microscopy (CLSM). This study shows enhanced synergistic antibacterial effects of the Nano-MIX on common oral bacterial biofilms, which could be potentially developed as a novel antimicrobial agent for clinical oral/periodontal care.
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http://dx.doi.org/10.3390/nano6040061DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5302556PMC
April 2016

Lipoteichoic acid from an clinical strain promotes TNF-α expression through the NF-κB and p38 MAPK signaling pathways in differentiated THP-1 macrophages.

Biomed Rep 2015 Sep 27;3(5):697-702. Epub 2015 Jul 27.

Faculty of Dentistry, University of Hong Kong, Hong Kong, SAR 999077, P.R. China.

To study the immune-inflammatory response and signaling mechanism of macrophages to purified () lipoteichoic acid (LTA), intact LTA was obtained from an clinical strain P25RC using the butanol method and hydrophobic interaction chromatography purification. The fractions containing LTA were determined using phosphate detection. Contaminations with lipopolysaccharide and proteins were excluded using the Limulus amoebocyte lysate assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, respectively. LTA was analyzed using nuclear magnetic resonance. Prior to LTA stimulation assays, THP-1 monocytes were pretreated with phorbol 12-myristate 13-acetate to differentiate into macrophages. Macrophages were treated with LTA in concentration gradients and cells without LTA treatment as the control. Gene expression of , and were evaluated by quantitative polymerase chain reaction. Tumor necrosis factor-α (TNF-α) and interleukin (IL)-10 were quantified using ELISA. The activated and total nuclear factor-κB (NF-κB) p65 and three mitogen-activated protein kinases (p38, ERK1/2 and JNK) were assessed using western blot analysis. LTA induced the gene expression of and whilst it downregulated , suggesting a -dependent and -independent immune-inflammatory activity. LTA stimulated the expression of pro-inflammatory cytokine TNF-α (P<0.05), but not the anti-inflammatory cytokine IL-10. In conclusion, LTA stimulated the expression of TNF-α in macrophages possibly through the NF-κB and p38 pathways.
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http://dx.doi.org/10.3892/br.2015.495DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4576493PMC
September 2015

Impact of Actinomyces naeslundii on bisphosphonate-related osteonecrosis of the jaws in ovariectomized rats with periodontitis.

J Craniomaxillofac Surg 2015 Oct 14;43(8):1662-9. Epub 2015 Jul 14.

Discipline of Oral Diagnosis & Polyclinics, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China. Electronic address:

Bisphosphonates-related osteonecrosis of the jaws (BRONJ) is a severe complication of BPs therapy with unknown pathogenesis. This study aimed to evaluate the impact of Actinomyces naeslundii (A. naeslundii) on the progression of BRONJ in ovariectomized (OVX) rat model with periodontal diseases. Sixty rats were randomly assigned into four groups. All rats underwent bilateral ovariectomy. Six weeks after surgery, animals with periodontitis induced by ligature placement were administrated with normal saline (NS), NS &A. naeslundii inoculation, zolecdronic acid (ZA) and ZA &A. naeslundii inoculation for 12 weeks, respectively. Loads of total bacteria and A. naeslundii in the mouth were assessed by real time PCR. After sacrifice, the mandibles were harvested for micro-computed tomography (micro-CT) and histological examination. Real-time PCR demonstrated that A. naeslundii was not routinely found in the rats and ZA treatment did not promote its accumulation. Micro-CT examination disclosed that ligature placement induced significant alveolar bone loss, which was greatly attenuated by ZA treatment and aggravated by A. naeslundii. Histological assessment demonstrated that ZA treatment increased the risk of developing BRONJ-like disease but this condition was not worsen with the presence of A. naeslundii. Our study suggested that oral A. naeslundii inoculation aggravated periodontal disease but not BRONJ in our animal model.
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http://dx.doi.org/10.1016/j.jcms.2015.07.001DOI Listing
October 2015

New "haploid biofilm model" unravels IRA2 as a novel regulator of Candida albicans biofilm formation.

Sci Rep 2015 Jul 23;5:12433. Epub 2015 Jul 23.

1] Institute of Molecular &Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore [2] Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.

Clinical isolates of the fungal human pathogen Candida albicans are invariably diploid and heterozygous, impeding genetic study. Recent isolation of C. albicans haploids opens opportunities to apply technologies unfeasible in diploids. However, doubts remain on whether the haploids, derived from chromosome loss, can represent the diploids. Here, we use C. albicans haploids to investigate biofilm, a key virulence attribute. We conducted the first comprehensive characterization of biofilm formation of the haploids in comparison with the diploids. We demonstrate that the haploids form biofilms with essentially the same characteristics as the diploids. Screening a haploid mutant library has uncovered novel GTPase-related genes as biofilm regulators, including IRA2 that encodes an activator of the Ras GTPase. IRA2-deletion mutants develop poorly constructed biofilm in both haploid and diploid C. albicans. Our results demonstrate that the haploids are a valid model for C. albicans biofilm research and a powerful tool for uncovering novel regulators.
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http://dx.doi.org/10.1038/srep12433DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5378891PMC
July 2015

Antifungal susceptibility and phenotypic characterization of oral isolates of a black fungus from a nasopharyngeal carcinoma patient under radiotherapy.

BMC Oral Health 2015 Mar 20;15:39. Epub 2015 Mar 20.

Department of Clinical Oncology, Li Ka Shing Faculty of Medicine, Queen Mary Hospital, The University of Hong Kong, 1/F, Professorial Block, Queen Mary Hospital, Pok Fu lam, Hong Kong.

Background: During a research project on fungal Candida species in patients wearing obturator treated with radiotherapy for their recurrent nasopharyngeal carcinoma, we serendipitously observed the presence of black fungus in two consecutive samples from a patient.

Case Presentation: The samples were collected from a 57 year-old Hong Kong gentleman who diagnosed to have undifferentiated type of nasopharyngeal carcinoma. He was treated with definitive concurrent chemoradiotherapy followed by adjuvant chemotherapy and then received a second-course radiotherapy with IMRT. 18S rDNA sequencing revealed that the isolates belong to Exophiala dermatitidis which was susceptible to fluconazole, itraconazole, ketoconazole and voriconazole. Interestingly, E. dermatitidis isolates were resistant to caspofungin and one isolate was resistant to amphotericin B. Both isolates formed biofilms comparable to that of Candida albicans. Single isolate of E. dermatitidis showed hemolysin and proteinase ability comparable to C. albicans whilst the other isolate was not.

Conclusion: We, for the first time, reported the discovery of a black fungus-E. dermatitidis isolates derived from a patient with nasopharyngeal carcinoma treated with radiotherapy. These isolates were shown to be resistant to caspofungin, a major antifungal agent for systemic candidiasis. As little is known about the black fungus in the clinical setting, it is important that clinicians must keep abreast of the new discovery in this field.
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http://dx.doi.org/10.1186/s12903-015-0023-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4381516PMC
March 2015

Role of periodontal disease in bisphosphonate-related osteonecrosis of the jaws in ovariectomized rats.

Clin Oral Implants Res 2016 Jan 5;27(1):1-6. Epub 2014 Nov 5.

Discipline of Oral Diagnosis & Polyclinics, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.

Objective: This study aimed to investigate the role of progressive periodontal disease in inducing bisphosphonate-related osteonecrosis of the jaws (BRONJ) using an ovariectomized (OVX) rat model mimicking human intracortical remodeling process.

Materials And Methods: Thirty 12-week-old Spraque-Dawly (SD) female rats were randomly assigned into two groups. All rats underwent bilateral ovariectomy. Six weeks after surgery, zoledronic acid (ZA) or vehicle control was administered intraperitoneally for 12 weeks. On the same day of injection, a cotton ligature was placed subgingivally around the first left lower molar to induce periodontitis. All animals were sacrificed 12 weeks after injection. The entire mandibles were harvested for micro-computed tomography (micro-CT) and histological examinations.

Results: Micro-CT examination showed that ligature placement caused significant alveolar bone loss both in ZA (0.63 ± 0.13 vs. 0.38 ± 0.06 mm, P < 0.001) and in control (0.88 ± 0.19 vs. 0.40 ± 0.06 mm, P < 0.001) groups. Whereas in the ZA group, bone loss was attenuated compared with the control group (P < 0.01); the bone mineral density in the ZA group (1.00 ± 0.02 g/cm(3)) was significantly higher than that in vehicle control group (0.96 ± 0.03 g/cm(3), P < 0.001). Histological examination found necrotic bone tissue with extensive, empty lacunae in two of 15 rats in ZA group, but in none of the control group.

Conclusion: Bisphosphonates inhibit alveolar bone resorption in progressive periodontal disease, which might benefit the management of periodontitis, but increase the risk of developing BRONJ.
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http://dx.doi.org/10.1111/clr.12502DOI Listing
January 2016

Nanoparticle-encapsulated chlorhexidine against oral bacterial biofilms.

PLoS One 2014 29;9(8):e103234. Epub 2014 Aug 29.

Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, China.

Background: Chlorhexidine (CHX) is a widely used antimicrobial agent in dentistry. Herein, we report the synthesis of a novel mesoporous silica nanoparticle-encapsulated pure CHX (Nano-CHX), and its mechanical profile and antimicrobial properties against oral biofilms.

Methodology/principal Findings: The release of CHX from the Nano-CHX was characterized by UV/visible absorption spectroscopy. The antimicrobial properties of Nano-CHX were evaluated in both planktonic and biofilm modes of representative oral pathogenic bacteria. The Nano-CHX demonstrated potent antibacterial effects on planktonic bacteria and mono-species biofilms at the concentrations of 50-200 µg/mL against Streptococcus mutans, Streptococcus sobrinus, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans and Enterococccus faecalis. Moreover, Nano-CHX effectively suppressed multi-species biofilms such as S. mutans, F. nucleatum, A. actinomycetemcomitans and Porphyromonas gingivalis up to 72 h.

Conclusions/significance: This pioneering study demonstrates the potent antibacterial effects of the Nano-CHX on oral biofilms, and it may be developed as a novel and promising anti-biofilm agent for clinical use.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0103234PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4149348PMC
May 2015

Evaluation of the Candida albicans removal and mechanical properties of denture acrylics cleaned by a low-cost powered toothbrush.

J Prosthodont Res 2014 Oct 20;58(4):243-51. Epub 2014 Jul 20.

Dental Materials Science, Faculty of Dentistry, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, P.R. China.

Purpose: To investigate the effects of using a low-cost powered toothbrush for cleaning on dental prostheses made of heat polymerized poly(methyl methacrylate), PMMA.

Methods: Heat cured PMMA specimens beam with the dimensions of 45.0 mm×6.5 mm×4.5mm were fabricated. The specimens were kept in water storage at 37 °C constant temperature for 0, 1, 7, 15, 30 and 60 days and randomly assigned for testing or control. Test specimens underwent brushing by using a powered toothbrush at an applied force of 2.00 N for 22 min with water as medium. Surface roughness measurement (Ra), flexural strength and efficacy of brushing to remove coated Candida albicans biofilm were investigated.

Results: The results of the mean surface roughness value and the flexural strength were analysed by using two-way ANOVA and Tukey post hoc test at 5% significance level. In general, the specimens showed no significant changes in flexural strength after brushing. However, the flexural strength and the surface roughness value were significantly lower in specimens group after 7 days in water storage compared to the control. SEM micrographs of post-brushed specimens revealed satisfactory removal of C. albicans biofilm.

Conclusion: A low-cost powered toothbrush together with a liquid medium successfully removed C. albicans biofilm on dental acrylic PMMA-based prostheses, without compromising the mechanical properties.
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http://dx.doi.org/10.1016/j.jpor.2014.06.002DOI Listing
October 2014

Biofilm formation of salivary microbiota on dental restorative materials analyzed by denaturing gradient gel electrophoresis and sequencing.

Dent Mater J 2014 4;33(3):325-31. Epub 2014 Mar 4.

Comprehensive Dental Care (Endodontics), Faculty of Dentistry, The University of Hong Kong.

The microbial diversity of biofilms formed on the surfaces of amalgam, glass-ionomer cement, and resin composite was analyzed by denaturing gradient gel electrophoresis (DGGE). The V2-V3 region of salivary microbial 16S rDNA gene sequences of planktonic and biofilm bacteria, after 1 day and 1 week of incubation, was amplified by polymerase chain reaction (PCR) and analyzed by DGGE. The amounts of strongly adherent phylotypes after 1 day and 1 week on the three dental restorative materials were more than those on hydroxyapatite. Streptococcus salivarius was detected in both loosely adherent and strong adherent groups of all 1-day samples. At 1 week, the amounts of loosely adherent and strongly adherent phylotypes present on the three restorative materials ranked in this ascending order: glass-ionomer cement < resin composite < amalgam. Results of DGGE analysis suggested that glass-ionomer cement was the best material of choice in terms of suppressing bacterial phylotypes in biofilms.
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http://dx.doi.org/10.4012/dmj.2013-152DOI Listing
May 2016

In vitro and in vivo activity of a novel antifungal small molecule against Candida infections.

PLoS One 2014 22;9(1):e85836. Epub 2014 Jan 22.

Faculty of Dentistry, University of Hong Kong, Hong Kong.

Candida is the most common fungal pathogen of humans worldwide and has become a major clinical problem because of the growing number of immunocompromised patients, who are susceptible to infection. Moreover, the number of available antifungals is limited, and antifungal-resistant Candida strains are emerging. New and effective antifungals are therefore urgently needed. Here, we discovered a small molecule with activity against Candida spp. both in vitro and in vivo. We screened a library of 50,240 small molecules for inhibitors of yeast-to-hypha transition, a major virulence attribute of Candida albicans. This screening identified 20 active compounds. Further examination of the in vitro antifungal and anti-biofilm properties of these compounds, using a range of Candida spp., led to the discovery of SM21, a highly potent antifungal molecule (minimum inhibitory concentration (MIC) 0.2-1.6 µg/ml). In vitro, SM21 was toxic to fungi but not to various human cell lines or bacterial species and was active against Candida isolates that are resistant to existing antifungal agents. Moreover, SM21 was relatively more effective against biofilms of Candida spp. than the current antifungal agents. In vivo, SM21 prevented the death of mice in a systemic candidiasis model and was also more effective than the common antifungal nystatin at reducing the extent of tongue lesions in a mouse model of oral candidiasis. Propidium iodide uptake assay showed that SM21 affected the integrity of the cell membrane. Taken together, our results indicate that SM21 has the potential to be developed as a novel antifungal agent for clinical use.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0085836PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3899067PMC
December 2014

The effects of natural compounds-containing mouthrinses on patients with fixed orthodontic appliance treatment: clinical and microbiological outcomes.

Int J Paediatr Dent 2013 Nov 28;23(6):452-9. Epub 2012 Dec 28.

Discipline of Orthodontics, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.

Aim: To investigate the effects of two natural compounds-containing mouthrinses (NCCMs) (a fructus mume (FM) extract-containing mouthrinse and an essential oil (EO)-containing mouthrinse) on gingival health and microbial profiles in young orthodontic patients.

Design: This 6-month randomized, single-blinded, parallel-controlled clinical trial consists of 90 patients with fixed appliance treatment. The subjects were allocated to (1) negative control group: oral hygiene instruction (OHI) alone; (2) test group 1: OHI plus EO mouthrinse; and (3) test group 2: OHI plus FM mouthrinse. Clinical examinations included plaque index (PI), bleeding index (BI) and modified gingival index (MGI). Salivary microbial quantifications included total aerobic and anaerobic bacteria, Streptococci and Lactobacilli counts. Clinical and microbiological examinations were conducted at baseline, 3rd and 6th months (T1, T2, and T3).

Results: BI was significantly reduced in both the FM mouthrinse and EO mouthrinse groups compared with the negative control group at T3 (P < 0.05). There were no significant intergroup differences in salivary bacteria counts in all groups (P > 0.05).

Conclusion: Both NCCMs effectively reduced gingival bleeding without causing significant alterations of microbial profile in young orthodontic patients.
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http://dx.doi.org/10.1111/ipd.12018DOI Listing
November 2013