Jonathan Pratten

University of Verona, Verona, Veneto, Italy

Are you Jonathan Pratten?

Claim your profile

Publications (102)280.78 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In previous works we have shown that a low-molecular-mass (LMM) fraction from mushroom (Lentinus edodes) homogenate interferes with binding of Streptococcus mutans to hydroxyapatite and Prevotella intermedia to gingival cells. Additionally, inhibition of biofilm formation of both odonto- and periodonto-pathogenic bacteria and detachment from preformed biofilms have been described for this compound. Further purification of mushroom extract has been recently achieved and a sub-fraction (i.e. # 5) has been identified as containing the majority of the mentioned biological activities. The aim of this study was to characterise the bacterial receptors for the purified mushroom sub-fraction #5 in order to better elucidate the mode of action of this compound when interfering with bacterial adhesion to host surfaces or with bacteria-bacteria interactions in the biofilm state. Candidate bacterial molecules to act as target of this compound were bacterial surface molecules involved in cell adhesion and biofilm formation, and, thus, we have considered cell wall associated proteins (CWPs), teichoic acid (TA) and lipoteichoic acid (LTA) of S. mutans, and outer membrane proteins (OMPs) and lipopolysaccharide (LPS) of P. intermedia. Fifteen S. mutans CWPs and TA were capable of binding sub-fraction#5, while LTA did not. As far as P. intermedia is concerned, we show that five OMPs interact with sub-fraction # 5. Capacity of binding to P. intermedia LPS was also studied but in this case negative results were obtained. Binding sub-fraction # 5 to surface molecules of S. mutans or P. intermedia may result in inactivation of their physiological functions. As a whole, these results indicate, at molecular level, the bacterial surface alterations affecting adhesion and biofim formation. For these antimicrobial properties, the compound may find use in daily oral hygiene.
    BMC Complementary and Alternative Medicine 02/2014; 14(1):75. · 2.08 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The low molecular mass (LMM) extract of Cichorium intybus var. silvestre (red chicory) has been shown to inhibit virulence-linked properties of oral pathogens including Streptococcus mutans, Actinomyces naeslundii and Prevotella intermedia. In the present study HPLC-DAD-ESI/MS(2) was used to investigate the compounds contained in this extract for their anti-virulence activity. The extract contained a number of components, including oxalic, succinic, shikimic and quinic acids, which interfere with the growth and virulence traits (i.e., biofilm formation, adherence to epithelial cells and hydroxyapatite) of oral pathogens involved in gingivitis and tooth decay. Succinic and quinic acid seem to be the most potent, mainly by interfering with the ability of oral pathogens to form biofilms (either through inhibition of their development or promotion of their disruption). Our findings suggest that one or more of these compounds may modulate plaque formation in vivo, which is a prerequisite for the development of both caries and gingivitis.
    Food Chemistry 06/2013; 138(2-3):1706-12. · 3.33 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: Dental caries is an infectious disease which results from the acidic demineralisation of the tooth enamel and dentine as a consequence of the dental plaque (a microbial biofilm) accumulation. Research showed that several foods contain some components with antibacterial and antiplaque activity. Previous studies indicated antimicrobial and antiplaque activities in a low-molecular-mass (LMM) fraction of extracts from either an edible mushroom (Lentinus edodes) or from Italian red chicory (Cichorium intybus). METHODS: We have evaluated the antimicrobial mode of action of these fractions on Streptococcus mutans, the etiological agent of human dental caries. The effects on shape, macromolecular syntheses and cell proteome were analysed. RESULTS: The best antimicrobial activity has been displayed by the LMM mushroom extract with a bacteriostatic effect. At the MIC of both extracts DNA synthesis was the main macromolecular synthesis inhibited, RNA synthesis was less inhibited than that of DNA and protein synthesis was inhibited only by roughly 50%. The partial inhibition of protein synthesis is compatible with the observed significant increase in cell mass. The increase in these parameters is linked to the morphological alteration with transition from cocci of the untreated control to elongated cells. Interestingly, these modifications were also observed at sub-MIC concentrations. Finally, membrane and cytosol proteome analysis was conducted under LMM mushroom extract treatment in comparison with untreated S. mutans cells. Significant changes were observed for 31 membrane proteins and 20 of the cytosol fractions. The possible role of the changed proteins is discussed. CONCLUSIONS: This report has shown an antibiotic-like mode of action of mushroom and chicory extracts as demonstrated by induced morphogenetic effects and inhibition of specific macromolecular synthesis. This feature as well as the safe use of this extract as result of its natural origin render the LMM both mushroom and chicory extracts suitable for the formulation into products for daily oral hygiene such as mouthwashes or toothpastes.
    BMC Complementary and Alternative Medicine 05/2013; 13(1):117. · 2.08 Impact Factor
  • Source
    Dallas Roulston, Jonathan Pratten, David Spratt
    [Show abstract] [Hide abstract]
    ABSTRACT: -Dental plaque is a biofilm that forms preferentially on the hard, non-shedding surface of the teeth. -Within plaque, the constituent bacteria are metabolically active, fermenting dietary carbohydrates and producing lactic acid. This along with their complex structure leads to ion-concentration microgradients forming within the biofilm. -Little is known about the complex processes that take place within dental plaque. -A more accurate method for the measurement of pH within dental plaque is needed to better understand how changes affect the overall composition and processes within the biofilm. Previous work to establish the existence of microgradients was performed using micro-electrodes[1,2]. Microelectrodes lack resolution, are destructive to the colony being analysed and may influence the measurement itself.
  • [Show abstract] [Hide abstract]
    ABSTRACT: OBJECTIVE: Development of high strength dental composites with adhesive, antibacterial and re-mineralizing potential. MATERIALS: Urethane and triethylene glycol dimethacrylates were combined with HEMA (10 or 20wt%) and 2MP (2 or 10wt%), antibacterial chlorhexidine (2.5wt%) and chemical cure initiators. Reactive mono/tri calcium phosphate (CP) mixed with silica/silicon carbide nanoparticles (S) (CP:S weight ratio 1:2 or 2:1) was added (50wt%). RESULTS: Decreasing CP/S ratio and HEMA content reduced monomer conversion at 15min from 93 to 63%. Conversely, decreasing CP/S increased initial "dry" compressive (137-203MPa) and flexural (79-116MPa) strength. With high HEMA content, these decreased by ∼15-20MPa upon 24h water storage. With low HEMA content, average decline was <8MPa due to reduced water sorption. Early water sorption induced mass increase, volume expansion, mono calcium phosphate dissolution and chlorhexidine release, were proportional to the initial calcium phosphate content. Furthermore, they increased ∼1.5 fold upon raising HEMA wt%. These diffusion controlled processes and strength decline slowed after 24h as phosphates reaction bound water within the materials. Increasing 2MP concentration reduced calcium release but did not affect strength. Formulations with high CP/S indicated greater antibacterial activity in agar diffusion and in vitro biofilm tests. SIGNIFICANCE: New material use beneath a conventional composite could potentially reduce high failure rates associated with residual caries and bacterial microleakage.
    Dental materials: official publication of the Academy of Dental Materials 02/2013; · 2.88 Impact Factor
  • Source
  • Source
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objective: To fractionate, sub-fractionate and test Shiitake mushroom homogenate in an iterative process, to identify the active components and test in a biofilm disruption assay with a view to using these as potential anti-caries and anti-gingivitis agents. Method: Shitake mushroom homogenates were iteratively fractionated (liquid chromatography, reverse phase HPLC and gel filtration chromatography) and active components identified using HPLC and mass spectroscopy. Mature biofilms of each of the test organisms (Streptococcus mutans and Actinomyces naeslundii ) were grown on cellulose nitrate membrane filters and incubated with the test compounds for 1 min. Viability staining (LIVE/DEAD BacLight) and fluorescence microscopy were used to estimate the number of live and dead cells disrupted from the biofilm as well as the number of live and dead cells remaining. Result: The active compounds in Shitake mushroom homogenates were identified as adenosine, quinic acid, inosine, oxalic acid and succinic acid. The disruption and killing assays showed that all of the compounds disrupted at least 60% of the S. mutans biofilm; oxalic acid being the most effective (disrupting 90% of the biofilm). Quinic acid was the most effective antimicrobial (killing over 60% of cells). Similar results were obtained for A. naeslundii biofilms with all compounds disrupting at least 60% of the biofilm and adenosine disrupting 80%. Inosine was most effective antimicrobial, killing 28% of disrupted cells. Conclusion: The active fractions and the pure isolated compounds showed promise at disrupting and killing biofilm-grown cells and may be of use as anti-caries and anti-gingivitis agents.
    IADR General Session 2012; 06/2012
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The main objective was to investigate whether low-molecular-weight fraction of edible mushroom shiitake extract (Lentinus edodes) possesses caries-preventive properties. The study was designed as a double-blind, three-leg, cross-over, randomized, controlled clinical trial carried out on two series of volunteers at the University of Gothenburg, and the Academic Centre for Dentistry Amsterdam. Volunteers rinsed twice daily with a solution containing low-molecular-weight fraction of edible mushroom, placebo (negative control without active ingredients), or Meridol (positive control, AmF-SnF(2)) for two weeks, with a two-week washout period between each rinsing period. Changes in the acidogenicity of dental plaque before and after a sucrose challenge, shifts in microbial composition, and plaque scores were determined. Frequent rinses with shiitake reduced the metabolic activity of dental plaque. No reduction of plaque scores and no inhibition of the production of organic acids in plaque was found. Minor differences in microbial composition between test sessions were found. To conclude, the results indicate that shiitake extract has anticariogenic potential, but not to the same extent as the positive control.
    BioMed Research International 01/2012; 2012:217164. · 2.71 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The link between diet and health has lead to the promotion of functional foods which can enhance health. In this study, the oral health benefits of a number of food homogenates and high molecular mass and low molecular mass fractions were investigated. A comprehensive range of assays were performed to assess the action of these foods on the development of gingivitis and caries using bacterial species associated with these diseases. Both antigingivitis and anticaries effects were investigated by assays examining the prevention of biofilm formation and coaggregation, disruption of preexisting biofilms, and the foods' antibacterial effects. Assays investigating interactions with gingival epithelial cells and cytokine production were carried out to assess the foods' anti- gingivitis properties. Anti-caries properties such as interactions with hydroxyapatite, disruption of signal transduction, and the inhibition of acid production were investigated. The mushroom and chicory homogenates and low molecular mass fractions show promise as anti-caries and anti-gingivitis agents, and further testing and clinical trials will need to be performed to evaluate their true effectiveness in humans.
    BioMed Research International 01/2012; 2012:510198. · 2.71 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Silicone polymers containing the light-activated antimicrobial agent methylene blue with or without gold nanoparticles were evaluated for their ability to reduce the microbial load on surfaces in a clinical environment. When irradiated with white light, polymers containing nanogold were more effective in this respect than those containing only methylene blue.
    Infection Control and Hospital Epidemiology 11/2011; 32(11):1130-2. · 4.02 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study has investigated novel bone adhesives consisting of fluid photo-polymerizable poly(lactide-co-propylene glycol-co-lactide)dimethacrylate (PGLA-DMA) mixed with systematically varying fillers of β-tricalcium phosphate (β-TCP) and monocalcium phosphate monohydrate (MCPM), for the delivery of an antibacterial drug chlorhexidine (CHX). All formulations were found to polymerize fully within 200 s after exposure to blue light. In addition, water sorption by the polymerized materials catalyzed varying filler conversion to dicalcium phosphate (DCP) (i.e. brushite and monetite). With greater DCP levels, faster degradation was observed. Moreover, increase in total filler content enhanced CHX release, associated with higher antibacterial activity. These findings thus suggest that such rapid-setting and degradable adhesives with controllable drug delivery property could have potential clinical value as bone adhesives with antibacterial activity.
    Journal of Materials Science Materials in Medicine 06/2011; 22(9):1993-2004. · 2.14 Impact Factor
  • Source
    Zoie A Aiken, Michael Wilson, Jonathan Pratten
    [Show abstract] [Hide abstract]
    ABSTRACT: ATP bioluminescence is being applied in hospitals to measure surface contamination. We compared commercial luminometers for detecting the number Staphylococcus aureus associated with surfaces. The data showed that the ATP bioluminescence methods tested were not robust enough to generate quantitative data on bacterial numbers, especially at low concentrations.
    Infection Control and Hospital Epidemiology 05/2011; 32(5):507-9. · 4.02 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Photodynamic therapy (PDT) has been proposed as a new technique to inactivate microorganisms as it does not lead to the selection of mutant resistant strains; a clear benefit compared to antibiotic treatment. PDT has also attracted the interest of nanotechnology as the effectiveness of the treatment can be greatly enhanced by the use of nanoparticles. In the last decade, different approaches to the combination of nanoparticles and PDT have been investigated in relation to the antimicrobial applications of the technique. One use of the nanoparticles is to improve the delivery of photosensitiser to the bacteria; others use the nanoparticles to improve the inactivation kinetics. A different approach utilises nanoparticles as a photosensitiser. In this review these diverse types of interactions will be described.
    Photochemical and Photobiological Sciences 03/2011; 10(5):712-20. · 2.92 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to determine the prevalence and proportions of opportunistic pathogens harboured on orthodontic retainers. First, Staphylococcus spp. and Candida spp. were isolated from the retainer's inner surface and from other mucosal surfaces of the subject's mouth by routine bacterial culture. The prevalence and proportions of these micro-organisms on retainers was compared in different areas of the mouth within a group of retainer wearers, and mucosal carriage was compared to a group of nonretainer wearers. Staphylococcus spp. were isolated from 50% of the retainers and comprised on average 8·4% of the viable microbiota. Candida spp. comprised 0·13% of the viable microbiota and were recovered from 66·7% of the retainers. Neither genus was isolated from nonretainer wearers. Second, the two most commonly worn retainers manufactured from different materials were sampled; again Staphylococcus spp. and Candida spp. were recovered; however, no statistical differences were observed between the devices. Opportunistic, nonoral, pathogenic micro-organisms were recovered from orthodontic retainers. It is possible that an orthodontic retainer could be a reservoir for opportunistic pathogens and act as a source of cross-, self- and re-infection.
    Letters in Applied Microbiology 02/2011; 52(5):501-5. · 1.63 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Bacterial attachment is highly dependent on a surfaces microstructure. For example, some rough surfaces provide grooves suitable for bacterial adhesion. Superhydrophobic surfaces with a Cassie-Baxter wetting mechanism are shown to prevent contact between a bacterium and surface attachment points. The surface used in this study is a highly rough thin film made from a silicone elastomer via an aerosol assisted chemical vapour deposition (AACVD) process. The films had water contact angles averaging 165°, a very low slip angle, and were capable of duplicating the Lotus effect. The ability of bacteria (Escherichia coli and Methicillin-resistant Staphylococcus aureus) to adhere to this surface was tested by submersion in a bacterial suspension. The superhydrophobic elastomer surfaces reduced the attachment of the bacteria tested, relative to the control surfaces of plain glass, and flat elastomeric films. The reduction in bacterial adhesion, without the external action of chemicals, gives the elastomer surface deposited with AACVD possible applications in biomedical and catering industries. This progressive study of bacterial adhesion is carried out on an AACVD prepared surface and presents adhesion results from both smooth and highly roughened elastomeric surfaces.
    Thin Solid Films 01/2011; 519(11):3722-3727. · 1.87 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Antimicrobial films containing silver nanoparticles on a titania substrate were prepared and shown to have marked visible light photocatalytic properties. The films could be transformed from purple (silver oxide) to orange (silver) by 254 nm, 365 nm or white light radiation and the process reversed when the films were stored in air and in the dark. The films were characterized by XRD, Raman, AFM, SEM, EDX, UV–Vis spectroscopy and XPS as well as tested for functionality using a range of techniques including water contact angle measurement, the photo-destruction of stearic acid to a range of light sources and antimicrobial activity against MRSA and Escherichia coli bacteria under hospital lighting conditions. XRD and Raman indicated that the films were anatase, X-ray photoelectron measurements confirmed the presence of silver loading on the titania surface and EDX showed silver doping in the TiO2 layer. There appears to be an interaction between the phonon resonance of the silver nanoparticles and the band onset of the titania leading to significant visible light photo-oxidation of stearic acid as well as visible light induced superhydrophilicity. Samples were tested for photo-degradation of stearic acid under three different lighting conditions: UVA – 365 nm, white light (commonly found in UK hospitals) and UVA filtered white light. The Ag oxide-titania films were seen to be active photocatalysts under visible light conditions as well as displaying white light induced superhydrophilicity. These surfaces demonstrated a 99.996% reduction in the number of viable E. coli bacteria due to the silver ion presence and a 99.99% reduction in the number of MRSA bacteria due to the enhanced photocatalysis in a double pronged approach to antimicrobial mechanisms consisting of a synergistic relationship between the photocatalyst (TiO2) and the surface bound silver nanoparticles.Graphical abstractPhotograph showing the difference in colour between sample Ag-TiO2 (purple on the left) and Ag-TiO2-UV (orange on the right). Note that the microscope slides contained a 1 cm well cavity ca. 1 mm deep to make them suitable for microbiology testing.Highlights► Antimicrobial films containing silver nanoparticles on a titania substrate were prepared and shown to have marked visible light photocatalytic properties. ► The films could be transformed from purple (silver oxide) to orange (silver) by 254 nm, 365 nm or white light radiation and the process reversed when the films were stored in air and in the dark. ► Duel action antimicrobial properties work from a combination of silver ion release and photoactivated properties.
    Journal of Photochemistry and Photobiology A: Chemistry. 01/2011; 220:113-123.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of the current study was to investigate the anticariogenic potential of the (sub)fractions obtained from the edible mushroom shiitake (Lentinula edodes) in in vitro caries model. We used a modified constant depth film fermentor (CDFF) with pooled saliva as the inoculum and bovine dentin as a substratum. The test compounds were low molecular weight fraction (MLMW) of the shiitake extract and subfractions 4 and 5 (SF4 and SF5) of this fraction. Chlorhexidine (CHX) and water served as a positive and a negative control, respectively. Dentin mineral loss was quantified (TMR), microbial shifts within the microcosms were determined (qPCR), and the acidogenicity of the microcosms was assessed (CIA). From the compounds tested, the SF4 of shiitake showed strong inhibiting effect on dentin demineralization and induced microbial shifts that could be associated with oral health. The acid producing potential was increased, suggesting uncoupling of the glycolysis of the microbiota by the exposure to SF4. In conclusion, the results suggest that SF4 of shiitake has an anticariogenic potential.
    BioMed Research International 01/2011; 2011:135034. · 2.71 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Low molecular mass (LMM) fractions obtained from extracts of raspberry, red chicory, and Shiitake mushrooms have been shown to be an useful source of specific antibacterial, antiadhesion/coaggregation, and antibiofilm agent(s) that might be used for protection towards caries and gingivitis. In this paper, the effects of such LMM fractions on human gingival KB cells exposed to the periodontal pathogens Prevotella intermedia and Actinomyces naeslundii were evaluated. Expression of cytokeratin 18 (CK18) and β4 integrin (β4INT) genes, that are involved in cell proliferation/differentiation and adhesion, and of the antimicrobial peptide β2 defensin (HβD2) in KB cells was increased upon exposure to either live or heat-killed bacteria. All LMM fractions tested prevented or reduced the induction of gene expression by P. intermedia and A. naeslundii depending on the experimental conditions. Overall, the results suggested that LMM fractions could modulate the effects of bacteria associated with periodontal disease in gingival cells.
    BioMed Research International 01/2011; 2011:230630. · 2.71 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Although foods are considered enhancing factors for dental caries and periodontitis, laboratory researches indicate that several foods and beverages contain components endowed with antimicrobial and antiplaque activities. A low molecular mass (LMM) fraction of an aqueous mushroom extract has been found to exert these activities in in vitro experiments against potential oral pathogens. We therefore conducted a clinical trial in which we tested an LMM fraction of shiitake mushroom extract formulated in a mouthrinse in 30 young volunteers, comparing the results with those obtained in two identical cohorts, one of which received water (placebo) and the other Listerine. Plaque index, gingival index and bacterial counts in plaque samples were determined in all volunteers over the 11 days of the clinical trial. Statistically significant differences (P < 0.05) were obtained for the plaque index on day 12 in subjects treated with mushroom versus placebo, while for the gingival index significant differences were found for both mushroom versus placebo and mushroom versus Listerine. Decreases in total bacterial counts and in counts of specific oral pathogens were observed for both mushroom extract and Listerine in comparison with placebo. The data suggest that a mushroom extract may prove beneficial in controlling dental caries and/or gingivitis/periodontitis.
    BioMed Research International 01/2011; 2011:857987. · 2.71 Impact Factor

Publication Stats

2k Citations
280.78 Total Impact Points

Institutions

  • 2011–2013
    • University of Verona
      • Department of Pathology and Diagnostics
      Verona, Veneto, Italy
    • VU University Amsterdam
      • Academic Centre for Dentistry Amsterdam (ACTA)
      Amsterdam, North Holland, Netherlands
  • 1995–2013
    • UCL Eastman Dental Institute
      Londinium, England, United Kingdom
  • 2012
    • University of Gothenburg
      • Department of Cariology
      Göteborg, Vaestra Goetaland, Sweden
  • 1999–2011
    • University College London
      • • Department of Chemistry
      • • Division of Infection and Immunity
      London, ENG, United Kingdom
  • 2010
    • Liverpool John Moores University
      Liverpool, England, United Kingdom
  • 2009
    • Loughborough University
      • Wolfson School of Mechanical and Manufacturing Engineering
      Loughborough, ENG, United Kingdom
  • 2008
    • University of Kent
      • School of Physical Sciences
      Cantorbery, England, United Kingdom
  • 2006
    • University of Groningen
      • Department of Orthodontics
      Groningen, Province of Groningen, Netherlands
  • 2005
    • University of Campinas
      Conceição de Campinas, São Paulo, Brazil
  • 1994–2001
    • University of London
      Londinium, England, United Kingdom