Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Streptococcus mutans, a major causal agent of dental caries, functions in nature as a component of a biofilm on teeth (dental plaque) and yet very little information is available on the physiology of the organism in such surface-associated communities. As a consequence, we undertook to examine the synthesis of proteins by planktonic and biofilm cells growing in a biofilm chemostat at pH 7.5 at a dilution rate of 0.1 h−1 (mean generation time=7 h). Cells were incubated with 14C-labelled amino acids, the proteins extracted and separated by two-dimensional electrophoresis followed by autoradiography and computer-assisted image analysis. Of 694 proteins analysed, 57 proteins were enhanced 1.3-fold or greater in biofilm cells compared to planktonic cells with 13 only expressed in sessile cells. Diminished protein expression was observed with 78 proteins, nine of which were not expressed in biofilm cells. The identification of enhanced and diminished proteins by mass spectrometry and computer-assisted protein sequence analysis revealed that, in general, glycolytic enzymes involved in acid formation were repressed in biofilm cells, while biosynthetic processes were enhanced. The results show that biofilm cells possess novel proteins, of as yet unknown function, that are not present in planktonic cells.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The study examines the effect of maxillary prosthetic appliances on the composition of the microflora in the peri-implant sulcus. Two groups of patients participated. One group consisted of 18 people with removable prostheses, and a second group of 9 people with fixed prostheses was chosen to match them in age. sex and function period of their prosthetic appliances. One implant site per patient was chosen for microbiological sampling, and the samples were taken on 2 separate occasions from all the subjects, with a 3-month interval. From those with removable prostheses, a further sample was collected by scraping a squared area from the mucosal side of the prosthesis. The prevalence of black-pigmented Porphyromonasl Prevotella. Actinohacllus actinomycetemcomitans, mutans streptococci, lactobacilli, enteric bacteria and yeasts was analysed using blood-agar and selective agar media. The results show that the prevalence was significantly higher for Lactohacillus, Prevotella spp. and yeasts in subjects with removable prostheses than in subjects with fixed prostheses. No significant difference was registered in the pattern of microbial composition in subjects with the removable prosthesis when the peri-implant sulcus plaque and the biofilm on the corresponding mucosal side of their prosthesis were examined. The insertion of a removable reconstruction to cover the area of the osseointegrated implants gave rise to a progressive change in the peri-implant plaque towards a-more aciduric micrdflora.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1600-051X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract. Cortisol is one of the primary mediators of the stress response, in the main having immunosuppressive effects. An important component of the host response in periodontal inflammation is gingival crevicular fluid (GCF), with constituents mainly derived from serum, Cortisol like many other steroids, is present in saliva but its occurrence in GCF does not seem to be documented, Unstimulated whole saliva was collected and GCF was sampled on filter disks. The samples were analysed by a modified RIA method for serum in such a way that small volumes and low concentrations could be measured. Our findings suggest that the total concentration of cortisol in GCF might be estimated to levels below 1/10 of that in serum. However, what appears as a distinctive feature is the considerable variation of the cortisol concentrations for individual teeth. To our knowledge, this is the first time cortisol has been measured in gingival crevicular fluid, and this opens Ihe prospects for further in vivo research.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Streptococcus mutans is a component of the dental plaque biofilm and a major causal agent of dental caries. Log-phase cells of the organism are known to induce an acid tolerance response (ATR) at sub-lethal pH values (∼5.5) that enhances survival at lower pH values such as those encountered in caries lesions. In this study, we have employed a rod biofilm chemostat system to demonstrate that, while planktonic cells induced a strong ATR at pH 5.5, biofilm cells were inherently more acid resistant than such cells in spite of a negligible induction of an ATR. Since these results suggested that surface growth itself triggered an ATR in biofilm cells, we were interested in comparing the effects of a pH change from 7.5 to 5.5 on protein synthesis by the two cell types. For this, cells were pulse labeled with [14C]-amino acids following the pH change to pH 5.5, the proteins extracted and separated by two-dimensional (2D) electrophoresis followed by autoradiography and computer-assisted image analysis. A comparison between the cells incubated at pH 5.5 and the control biofilm cells revealed 23 novel proteins that were absent in the control cells, and 126 proteins with an altered relative rate of synthesis. While the number of changes in protein expression in the biofilm cells was within the same range as for planktonic cells, the magnitude of their change was significantly less in biofilm cells, supporting the observation that acidification of biofilm cells induced a negligible ATR. Mass spectrometry and computer-assisted protein sequence analysis revealed that ATR induction of the planktonic cells resulted in the downregulation of glycolytic enzymes presumably to limit cellular damage by the acidification of the external environment. On the other hand, the glycolytic enzymes in control biofilm cells were significantly less downregulated and key enzymes, such as lactate dehydrogenase were upregulated during pH 5.5 incubation, suggesting that the enhanced acid resistance of biofilm cells is associated with the maintenance of pH homeostasis by H+ extrusion via membrane ATPase and increased lactate efflux.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1436-3771
    Keywords: Key words Organic acids ; Plaque weight ; Streptococcus mutans ; Lactobacilli ; Dental caries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The aim was to investigate the composition and concentration of organic acids produced by plaque bacteria in vivo and its possible relation to caries development in schoolchildren. Sucrose-exposed pooled plaque from 25 healthy teenagers was collected and the levels of Streptococcus mutans and lactobacilli were estimated. The acid anions were analysed with isotachophoresis. The prevalence and incidence of dental caries during a 2-year period was recorded. Depending on the amount of plaque collected, the subjects were divided into a low (n=12) and a high (n=13) plaque weight group. The dominating anions in sucrose exposed plaque were lactate, acetate and propionate. For the entire study group, no association was found between the total acid concentration and caries development but for the participants with low plaque weight a positive relationship (P〈0.01) was disclosed. No correlation was found between the concentrations of acids and the number of lactobacilli or Streptococcus mutans. The present results did not suggest that the acidogenicity of sugar-exposed pooled plaque samples was a suitable indicator of caries activity in teenagers.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...