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Molecular Oral Microbiology

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https://www.readbyqxmd.com/read/28776953/establishment-of-oral-bacterial-communities-in-germ-free-mice-and-the-influence-of-recipient-age
#1
Yingying Wu, Caroline Westwater, E Xiao, Jôice Dias Corrêa, Wenmei Xiao, Dana T Graves
The acquisition of the oral microbiome is a complex process. We examined how the timing of microbial exposure alters bacterial colonization of the tooth surface. Germ-free mice were conventionalized by exposure to specific pathogen free (SPF) mice to acquire a commensal microbiome over three distinct four week periods, 0-4 weeks of age (Conv0-4w), 4-8 weeks (Conv4-8w), or 8-12 weeks (Conv8-12w). Bacterial DNA was extracted from the tooth surface and analyzed by 16S rDNA sequencing. Total bacteria and inflammatory cytokine expression in gingiva were determined by quantitative real-time PCR...
August 4, 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/28744965/expression-of-brpa-in-streptococcus-mutans-is-regulated-by-fnr-box-mediated-repression
#2
Sumei Liao, Arpan De, Tatyana Thompson, Lynne Chapman, Jacob P Bitoun, Xin Yao, Qingzhao Yu, Fangrui Ma, Zezhang T Wen
Our previous studies showed that brpA in S. mutans, which encodes a member of the LytR-CpsA-Psr family of proteins, can be cotranscribed with brpB upstream as a bicistronic operon, while the intergenic region also has strong promoter activity. To elucidate how brpA expression is regulated, the promoter regions were analyzed using PCR-based deletions and site-directed mutagenesis and a promoterless luciferase gene as a reporter. Allelic exchange mutagenesis was also used to examine genes encoding putative trans-acting factors, and the impact of such mutations on brpA expression was analyzed by reporter assays...
July 26, 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/28727895/how-to-become-a-killer-or-is-it-all-accidental-virulence-strategies-in-oral-streptococci
#3
Izabela Sitkiewicz
Streptococci are a diverse group of gram positive microorganisms sharing common virulence traits and similar strategies to escape the oral niche and establish an infection in other parts of the host organism. Invasive infection with oral streptococci is "a perfect storm" that requires the concerted action of multiple biotic and abiotic factors. Our understanding of streptococcal pathogenicity and infectivity should probably be less mechanistic and driven not only by the identification of novel virulence factors...
July 20, 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/28654195/dynamics-of-the-oral-microbiota-as-a-tool-to-estimate-time-since-death
#4
Joe Adserias Garriga, Narciso M Quijada, Marta Hernandez, David Rodríguez Lázaro, Dawnie Steadman, Jesús Garcia-Gil
Oral cavity harbors one of the most diverse microbiomes in the human body. It has been shown to be the second most complex in the body after the gastro- intestinal tract. Upon death, the indigenous microorganisms lead the decomposition of the carcass. Therefore, oral cavity and gastro-intestinal tract microbiomes, play a key role in human decomposition. The aim of the present study is to monitor the microbiome of decaying bodies on a daily basis and to identify signature bacterial taxa, that can improve postmortem interval estimation...
June 27, 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/28609586/targeted-antimicrobial-therapy-in-the-microbiome-era
#5
REVIEW
Victoria N Stone, Ping Xu
Even though the oral microbiome is one of the most complex sites on the body it is an excellent model for narrow-spectrum antimicrobial therapy. Current research indicates disruption of the microbiome leads to a dysbiotic environment allowing for the overgrowth of pathogenic species and the onset of oral diseases. The gram-negative colonizer, Porphyromonas gingivalis has long been considered a key player in the initiation of periodontitis and Streptococcus mutans has been linked to dental caries. With antibiotic research still on the decline, new strategies are greatly needed to combat infectious diseases...
June 13, 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/28548373/role-of-de-n-acetylase-pgab-from-aggregatibacter-actinomycetemcomitans-in-exopolysaccharide-export-in-biofilm-mode-of-growth
#6
Mayilvahanan Shanmugam, Abimbola O Oyeniyi, Chaitra Parthiban, Satish Kumar Gujjarlapudi, Gerald B Pier, Narayanan Ramasubbu
Aggregatibacter actinomycetemcomitans, a Gram-negative bacterium, is the causative agent of localized aggressive periodontitis. Attachment to a biotic surface is a critical first step in the A. actinomycetemcomitans infection process for which exopolysaccharides have been shown to be essential. In addition, the pga operon, containing genes encoding for biosynthetic proteins for poly-N-acetyl glucosamine (PNAG), plays a key role in A. actinomycetemcomitans virulence, as a mutant strain lacking the pga operon induces significantly less bone resorption...
May 26, 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/28544588/the-in-vivo-th17-and-treg-immune-responses-to-aggregatibacter-actinomycetemcomitans
#7
Susan Mahabady, Natalia Tjokro, Shant Aharonian, Homayoun H Zadeh, Casey Chen, Hooman Allayee, Parish P Sedghizadeh
The periodontal pathogen Aggregatibacter actinomycetemcomitans is known to elicit systemic immune response in infected host, and occasionally causes non-oral infections. Detailed information on its immunopathological responses and the involvement of bacterial virulence factors remains to be elucidated. The aim of this study was to assess the systemic immune response to A. actinomycetemcomitans oral infection. We used an animal model that simulates systemic dissemination of the bacteria by injecting live wild type (WT) D7S-1 and double knockout mutant of leukotoxin and cytolethal distending toxin (ΔltxΔcdt) A...
May 22, 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/28681571/corrigendum
#8
(no author information available yet)
No abstract text is available yet for this article.
August 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/27714987/in-vitro-characterization-of-biofilms-formed-by-kingella-kingae
#9
J B Kaplan, V Sampathkumar, M Bendaoud, A K Giannakakis, E T Lally, N V Balashova
The Gram-negative bacterium Kingella kingae is part of the normal oropharyngeal mucosal flora of children <4 years old. K. kingae can enter the submucosa and cause infections of the skeletal system in children, including septic arthritis and osteomyelitis. The organism is also associated with infective endocarditis in children and adults. Although biofilm formation has been coupled with pharyngeal colonization, osteoarticular infections, and infective endocarditis, no studies have investigated biofilm formation in K...
August 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/27498608/structure-function-aspects-of-the-porphyromonas-gingivalis-tyrosine-kinase-ptk1
#10
C Liu, D P Miller, Y Wang, M Merchant, R J Lamont
The development of synergistically pathogenic communities of Porphyromonas gingivalis and Streptococcus gordonii is controlled by a tyrosine-phosphorylation-dependent signaling pathway in P. gingivalis. The Ptk1 bacterial tyrosine (BY) kinase of P. gingivalis is required for maximal community development and for the production of extracellular polysaccharide. We show that the consensus BY kinase Walker A and B domains, the RK cluster, and the YC domain of Ptk1 are necessary for autophosphorylation and for substrate phosphorylation...
August 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/27476978/nucleases-from-prevotella-intermedia-can-degrade-neutrophil-extracellular-traps
#11
M Doke, H Fukamachi, H Morisaki, T Arimoto, H Kataoka, H Kuwata
Periodontitis is an inflammatory disease caused by periodontal bacteria in subgingival plaque. These bacteria are able to colonize the periodontal region by evading the host immune response. Neutrophils, the host's first line of defense against infection, use various strategies to kill invading pathogens, including neutrophil extracellular traps (NETs). These are extracellular net-like fibers comprising DNA and antimicrobial components such as histones, LL-37, defensins, myeloperoxidase, and neutrophil elastase from neutrophils that disarm and kill bacteria extracellularly...
August 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/27448788/activation-of-the-trem-1-pathway-in-human-monocytes-by-periodontal-pathogens-and-oral-commensal-bacteria
#12
M Varanat, E M Haase, J G Kay, F A Scannapieco
Periodontitis is a highly prevalent disease caused in part by an aberrant host response to the oral multi-species biofilm. A balance between the oral bacteria and host immunity is essential for oral health. Imbalances in the oral microbiome lead to an uncontrolled host inflammatory response and subsequent periodontal disease (i.e. gingivitis and periodontitis). TREM-1 is a signaling receptor present on myeloid cells capable of acting synergistically with other pattern recognition receptors leading to amplification of inflammatory responses...
August 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/28317288/tribute
#13
J London, D Lunsford, R J Palmer
No abstract text is available yet for this article.
June 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/27476770/the-road-less-traveled-defining-molecular-commensalism-with-streptococcus-sanguinis
#14
REVIEW
J Kreth, R A Giacaman, R Raghavan, J Merritt
The commensal oral microbial flora has evolved with the human host to support colonization of the various intraoral sites without triggering a significant immune response. In exchange, the commensal microbes provide critical protection against invading pathogens. The intrinsic ability of the oral flora to create a symbiotic microbial community with the host can be disturbed, selecting for the overgrowth of a dysbiotic community that can result in dental diseases, such as caries and periodontitis. Although the mechanisms of molecular pathogenesis in oral diseases are well characterized, much less is known about the molecular mechanisms used by the commensal flora to maintain oral health...
June 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/27346827/immunologic-environment-influences-macrophage-response-to-porphyromonas-gingivalis
#15
G Papadopoulos, Y B Shaik-Dasthagirisaheb, N Huang, G A Viglianti, A J Henderson, A Kantarci, F C Gibson
Macrophages adapt both phenotypically and functionally to the cytokine balance in host tissue microenvironments. Recent studies established that macrophages contribute an important yet poorly understood role in the development of infection-elicited oral bone loss. We hypothesized that macrophage adaptation to inflammatory signals encountered before pathogen interaction would significantly influence the subsequent immune response of these cells to the keystone oral pathobiont Porphyromonas gingivalis. Employing classically activated (M1) and alternatively activated (M2) murine bone-marrow-derived macrophage (BMDMø), we observed that immunologic activation of macrophages before P...
June 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/27224005/global-tlr2-and-4-deficiency-in-mice-impacts-bone-resorption-inflammatory-markers-and-atherosclerosis-to-polymicrobial-infection
#16
S S Chukkapalli, I M Velsko, M F Rivera-Kweh, H Larjava, A R Lucas, L Kesavalu
Toll-like-receptors (TLRs) play a significant role in the generation of a specific innate immune response against invading pathogens. TLR2 and TLR4 signaling contributes to infection-induced inflammation in periodontal disease (PD) and atherosclerosis. Observational studies point towards a relationship between PD and atherosclerosis, but the role of TLR2 and TLR4 in the recognition of multiple oral pathogens and their modulation of host response leading to atherosclerosis are not clear. We evaluated the role of TLR2 and TLR4 signaling in the induction of both PD and atherosclerosis in TLR2(-/-) and TLR4(-/-) mice to polymicrobial infection with periodontal pathogens Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, and Fusobacterium nucleatum...
June 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/27194631/effect-of-salivary-agglutination-on-oral-streptococcal-clearance-by-human-polymorphonuclear-neutrophil-granulocytes
#17
A Itzek, Z Chen, J Merritt, J Kreth
Salivary agglutination is an important host defense mechanism to aggregate oral commensal bacteria as well as invading pathogens. Saliva flow and subsequent swallowing more easily clear aggregated bacteria compared with single cells. Phagocytic clearance of bacteria through polymorphonuclear neutrophil granulocytes also seems to increase to a certain extent with the size of bacterial aggregates. To determine a connection between salivary agglutination and the host innate immune response by phagocytosis, an in vitro agglutination assay was developed reproducing the average size of salivary bacterial aggregates...
June 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/28502123/novel-method-for-the-depletion-of-cariogenic-bacteria-using-dextranomer-microspheres
#18
Lauren Mashburn-Warren, Jennifer S Downey, Steven D Goodman
Streptococcus mutans is recognized as one of the key contributors to the dysbiotic state that results in dental caries. While existing treatment strategies reduce the incidence of tooth decay, they also eliminate both the cariogenic and beneficial microbes. Here we introduce a novel treatment alternative using Sephadex, cross-linked dextranomer microspheres (DMs), typically used for gel filtration chromatography. In addition DM beads can be used for affinity purification of glucosyltransferases (GTFs) from S...
May 14, 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/28453906/oral-treponeme-major-surface-protein-sequence-diversity-and-distributions-within-periodontal-niches
#19
Meng You, Yuki Chan, Donnabella C Lacap-Bugler, Yong-Biao Huo, Wenling Gao, W Keung Leung, Rory M Watt
Treponema denticola and other species (phylotypes) of oral spirochetes are widely-considered to play important etiological roles in periodontitis and other oral infections. The major surface protein (Msp) of T. denticola is directly implicated in several pathological mechanisms. Here, we have analyzed msp sequence diversity across 68 strains of oral phylogroup 1 and 2 treponemes; including reference strains of T. denticola, Treponema putidum, Treponema medium, 'Treponema vincentii', and 'Treponema sinensis'...
April 28, 2017: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/28383798/survival-of-an-aggregatibacter-actinomycetemcomitans-quorum-sensing-luxs-mutant-in-the-mouths-of-rhesus-monkeys-insights-into-ecological-adaptation
#20
Senthil Kumar Velusamy, Vandana Sampathkumar, Dipti Godboley, Daniel H Fine
Experiments were designed to explore a prominent autoinducer-2 (AI-2) producing gene (luxS) related to colonization and survival of Aggregatibacter actinomycetemcomitans, a low abundance member of the indigenous flora, that forms a key component of the dysbiotic flora in localized aggressive periodontitis. The luxS gene was disrupted in a primate strain of A. actinomycetemcomitans prior to implantation into the oral cavity of Rhesus monkeys (Rh). The colonization efficiency of the luxS mutant (RhAa-VS4) was compared to the parental wild-type strain (RhAa3) (positive control) and a ltxA mutant (RhAa-VS2) (negative control)...
April 6, 2017: Molecular Oral Microbiology
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