Abstract Introduction The aims of this study were to evaluate the antibacterial and biofilm eradication efficacies of N-acetylcysteine (NAC) on Enterococcus faecalis. Methods The minimum inhibitory ...concentration (MIC) and minimum bactericidal concentration (MBC) of NAC on E. faecalis were determined. In addition, the ability of dentin powder to neutralize the antibacterial activity of NAC was examined. Calcium hydroxide, a commonly used intracanal medicament, was included as a comparison. The efficacy of NAC on E. faecalis biofilms was tested by exposure of 21-day old E. faecalis biofilms to NAC. Results NAC was most bactericidal at pH 11 with MIC and MBC of 1.56 mg/mL and 12.5 mg/mL, respectively. Although preincubation of calcium hydroxide with dentin powder abolished its antibacterial effects, NAC completely killed E. faecalis regardless of dentin powder preincubation. In addition, prolonged incubation of NAC with dentin powder (up to 3 weeks) did not significantly reduce its antibacterial activity on E. faecalis . Furthermore, NAC also effectively eradicated E. faecalis biofilms. Conclusions NAC was bactericidal against both the planktonic and biofilm forms of E. faecalis . This antibacterial property of NAC was unaffected by the presence of dentin.
Recent studies have shown that morphine modulates the function of glia cells through both opioid receptor dependent and independent mechanisms. However, the mechanism by which morphine regulates ...neuronal disorders through the alteration of microglia activity remains unclear. In this study, using rat primary mesencephalic neuron-glia cultures, we report that both l-morphine and its synthetic stereoenantiomer, d-morphine, an ineffective opioid receptor agonist, significantly reduced LPS- or 1-methyl-4-phenylpyridinium-induced dopaminergic neurotoxicity with similar efficacy, indicating a nonopioid receptor-mediated effect. In addition, using reconstituted neuron and glia cultures, subpicomolar concentrations of morphine were found to be neuroprotective only in the presence of microglia, and significantly inhibited the production of inflammatory mediators from LPS-stimulated microglia cells. Mechanistic studies showed that both l- and d- morphine failed to protect dopaminergic neurons in cultures from NADPH oxidase (PHOX) knockout mice and significantly reduced LPS-induced PHOX cytosolic subunit p47(phox) translocation to the cell membrane by inhibiting ERK phosphorylation. Taken together, our results demonstrate that morphine, even at subpicomolar concentrations, exerts potent anti-inflammatory and neuroprotective effects either through the inhibition of direct microglial activation by LPS or through the inhibition of reactive microgliosis elicited by 1-methyl-4-phenylpyridinium. Furthermore, our study reveals that inhibition of PHOX is a novel site of action for the mu-opioid receptor-independent effect of morphine.
Highlights • Twenty-seven subjects undergoing periodontal maintenance were recruited to participate in the present study aimed at determining the efficacy of adjunctive photodynamic therapy (PDT) on ...residual pockets • At 3 months test sites showed significant reduction in probing pocket depths and clinical attachment loss • In the short-term, application of adjunctive PDT may lead to faster resolution of residual pockets
Burkholderia pseudomallei is a Gram-negative saprophyte that is the causative agent of melioidosis, a severe infectious disease endemic in Northern Australia and Southeast Asia. This organism has ...sparked much scientific interest in the West because of its classification as a potential bioterrorism agent by the U.S. Centers for Disease Control and Prevention. However, relatively little is known about its pathogenesis. We demonstrate that B. pseudomallei actively inhibits NF-kappaB and type I IFN pathway activation, thereby downregulating host inflammatory responses. We found the virulence factor TssM to be responsible for this activity. TssM interferes with the ubiquitination of critical signaling intermediates, including TNFR-associated factor-3, TNFR-associated factor-6, and IkappaBalpha. The expression but not secretion of TssM is regulated by the type III secretion system. We demonstrate that TssM is important for B. pseudomallei infection in vivo as inflammation in the tssM mutant-infected mice is more severe and corresponds to a more rapid death compared with wild-type bacteria-infected mice. Abs to TssM can be detected in the sera of melioidosis patients, indicating that TssM is functionally expressed in vivo and thus could contribute to bacterial pathogenesis in human melioidosis.
Gingival and periodontal ligament fibroblasts are functionally distinct cell types within the dento-gingival unit that participate in host immune response. Their microenvironment influences the ...behavior and immune response to microbial challenge. We developed three-dimensional gingival and periodontal connective tissue equivalents (CTEs) using human fibrin-based matrix. The CTEs were characterized, and the heterogeneity in their innate immune response was investigated. The CTEs demonstrated no to minimal response to planktonic Streptococcus mitis and Streptococcus oralis, while their biofilms elicited a moderate increase in IL-6 and IL-8 production. In contrast, Fusobacterium nucleatum provoked a substantial increase in IL-6 and IL-8 production. Interestingly, the gingival CTEs secreted significantly higher IL-6, while periodontal counterparts produced higher IL-8. In conclusion, the gingival and periodontal CTEs exhibited differential responses to various bacterial challenges. This gives insights into the contribution of tissue topography and fibroblast heterogeneity in rendering protective and specific immune responses toward early biofilm colonizers.
A role for monocyte/macrophage modulation of wound healing at endosseous implants is proposed. The modification of the endosseous implant surface topography can alter cell adhesion and resultant cell ...behavior. The aim of this study was to define the effect of increased cpTitanium surface topography on adherent J744A.1 macrophage phenotype in culture. The J744A.1 cells were cultured on 20
mm diameter cpTitanium disks prepared with smooth and grit-blasted/acid rough surface topographies for 24–72
h. Following culture in growth media with or without lipopolysaccharide (LPS), total RNA was isolated and real-time polymerase chain reaction (PCR) was used to measure the steady-state levels of the pro-inflammatory cytokines interleukin 1-beta (IL-1
β) and interleukin 6 (IL-6) and the anti-inflammatory cytokine interleukin-10 (IL-10). Additional evidence of pro-inflammatory signaling was sought by measurement of cellular nitric oxide (NO) production. In the absence of LPS, IL-1
β levels were increased on grit-blasted/acid rough surfaces during the first 48
h. In contrast, IL-6 levels were reduced on the grit-blasted/acid rough surfaces. When cultures were treated with LPS, high levels of IL-1
β and IL-6 expression were measured, irrespective of surface topography. The responses of J744A.1 cells to surface and superimposed LPS stimulation suggest only modest effects of the modeled endosseous implant surface on adherent cell pro-inflammatory cytokine expression and NO signaling.
The D-DART (Droplet and Aerosol Reducing Tent) is a foldable design that can be attached to the dental chair to prevent the spread of contaminated dental aerosols. The objective of this study was to ...evaluate the ability of the D-DART to reduce spread of aerosols generated during dental treatment. Thirty-two patients (sixteen per group) undergoing deep ultrasonic scaling were recruited and randomly allocated to groups D-DART or Control (no D-DART). After 20 min from the start of the treatment, the clinician’s face shield and dental chair light were swabbed and the viable microbial load was quantified (ATP bioluminescence analysis, blinded operator). Statistical analyses were performed with Tukey’s Honest Test with a level of significance pre-set at 5%. There were significant increases in ATP values obtained from the operator’s face shield and dental chair light for the Control compared with baseline (31.3 ± 8.5 and fold increase). There was no significant change in microbial load when the D-DART was used compared with baseline (1.5 ± 0.4 fold increase). The D-DART contained and prevented the spread of aerosols generated during deep scaling procedures.
Abstract Introduction Alkaline-tolerant bacteria in primary infected root canals could have enhanced survival capacity against antimicrobials commonly used in root canal treatment. The aims of this ...study were to isolate and characterize alkaline-tolerant bacteria before endodontic treatment (S1), after chemomechanical root canal preparation (S2), and after calcium hydroxide dressing (S3). Methods Bacteriologic samples were obtained from 43 primary infected root canals. Samples were inoculated into culture media at a pH of 9 and incubated anaerobically. The identities of bacterial isolates were determined by 16S ribosomal RNA sequencing. Results All S1 samples were culture positive, with 70% harboring bacteria tolerating a pH of 9. Gram-positive bacteria Pseudoramibacter alactolyticus and Streptococcus spp were the most frequently isolated strains with a prevalence of 54%. Of 13 culture-positive S2 samples, 8 isolates tolerated a pH of 9, namely Streptococcus sanguinis , Enterococcus faecalis , Enterobacter cancerogenus , Streptococcus oralis , and Fusobacterium nucleatum . Seven of these 8 isolates (88%) were correspondingly isolated at S1. All 3 culture-positive S3 samples tolerated a pH of 9, namely S. sanguinis and E. faecalis, which were also isolated in the corresponding S1 and S2 samples. Conclusions We showed that the presence of alkaline-tolerant Streptococcus and Enterococcus spp in primary infected root canals could lead to their persistence during and after root canal treatment and could pose a challenge to current treatment efficacy.
Abstract Introduction Calcium hydroxide (CaOH2 ) is a widely used interappointment dressing, but its antibacterial property is compromised by dentin. Hence, the addition of chlorhexidine (CHX) with ...Ca(OH)2 has been proposed. However, the antimicrobial efficacy of this mixture compared with Ca(OH)2 alone is currently still debatable. Cysteamine is a mucolytic agent used to reduce the viscosity of mucus through the disruption of proteins, which are also important components of the extracellular matrix of biofilms. The aims of this study were to determine the efficacy of cysteamine alone and in combination with Ca(OH)2 to eradicate Enterococcus faecalis biofilm compared with CHX with Ca(OH)2 , and to determine if this effect is affected by dentin. Methods The biofilm eradication efficacies of Ca(OH)2 alone and with cysteamine were determined using 7-day E. faecalis biofilm cultured on dentin discs and compared with Ca(OH)2 with 2% CHX. The effects of dentin on the efficacies of Ca(OH)2 alone and with either cysteamine or CHX were examined. Results Cysteamine alone completely abolished E. faecalis biofilm at 200 mg/mL. The combination of Ca(OH)2 with either cysteamine at 10 mg/mL or 2% CHX completely obliterated E. faecalis biofilm. Cysteamine with Ca(OH)2 completely eradicated E. faecalis biofilm despite preincubation with dentin, whereas CHX with Ca(OH)2 was less effective. Conclusions Cysteamine effectively eliminated E. faecalis biofilm and showed synergistic effects in combination with Ca(OH)2 , which were unaffected by dentin. Hence, our findings support the use of cysteamine as a potential adjunct to Ca(OH)2 as an interappointment dressing.
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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