summary A continuous flow system was developed to evaluate the adhesion of Streptococcus mutans ATCC 25175 to filling materials (Ariston, Tetric, Dyract, Compoglass, Vitremer, Aqua Ionofil, Ketac ...Fil, amalgam, Galloy and ceramics as controls). Streptococcus mutans was added to saliva‐coated test specimens, and a nutrient broth permanently supplied over a time period of 48 h and then the weight of plaque, the number and viability of the bacteria adhering to the materials were determined. The weights of artificial plaque on all filling materials tested were higher than those on ceramics, the highest values were measured on the glass–ionomers. The amount of plaque correlates with the surface roughness, whereas there was no correlation of the surface roughness with the number of colony‐forming units (CFU) of S. mutans. The CFU of adhering S. mutans also depends on the viability of the bacteria. The plaque on Ketac Fil contained a high number of viable bacteria. The fluorides of glass–ionomers do not efficiently prevent the attachment and the viability of S. mutans.
Background and Objective: This study analyzed the interaction of Porphyromonas gingivalis ATCC 33277 and Aggregatibacter actinomycetemcomitans Y4 with peripheral blood polymorphonuclear neutrophils ...taken from patients with aggressive periodontitis and chronic periodontitis.
Material and Methods: Peripheral blood polymorphonuclear neutrophils obtained from 12 patients with chronic periodontitis, six patients with aggressive periodontitis and 12 healthy controls were exposed to P. gingivalis and A. actinomycetemcomitans following opsonization of the bacteria using the patient’s own serum. Serum immunoglobulin G (IgG) levels against both periodontopathogens were measured. Phagocytosis and killing of the bacteria, as well as the extracellular human neutrophil elastase activity, were quantified. The total amount and the extracellular release of reactive oxygen species were measured using luminol‐dependent and isoluminol‐dependent chemiluminescence.
Results: Polymorphonuclear neutrophils from patients with chronic (62.16 ± 19.39%) and aggressive (43.26 ± 26.63%) periodontitis phagocytosed more P. gingivalis than the healthy controls (24.43 ± 19.87%) at the 30‐min time point after exposure to the bacteria (p < 0.05). High serum IgG levels against P. gingivalis and A. actinomycetemcomitans were detected in subjects with periodontitis. Polymorphonuclear neutrophils from subjects with chronic and aggressive periodontitis released significantly more reactive oxygen species and demonstrated greater human neutrophil elastase activity in the absence of any stimulus than polymorphonuclear neutrophils from healthy controls (p < 0.05). Polymorphonuclear neutrophils in chronic periodontitis released significantly more reactive oxygen species when exposed to P. gingivalis and A. actinomycetemcomitans than polymorphonuclear neutrophils in aggressive periodontitis.
Conclusion: High serum IgG levels against P. gingivalis and A. actinomycetemcomitans promote phagocytosis in periodontitis. The extracellular release of reactive oxygen species and neutrophil elastase by polymorphonuclear neutrophils may also contribute to damage of the surrounding periodontal tissues.
Electrolyte-gate field-effect transistors (EG-FETs) gained continuously more importance in the field of bioelectronics. The reasons for this are the intrinsic properties of these FETs. Binding of ...analysts or changes in the electrolyte composition are leading to variations of the drain-source current. Furthermore, due to the signal amplification upon voltage-to-current conversion even small extracellular signals can be detected. Here we report about impedance spectroscopy with an FET array to characterize passive components of a cell attached to the transistor gate. We developed a 16-channel readout system, which provides a simultaneous, lock-in based readout. A test signal of known amplitude and phase was applied via the reference electrode. We monitored the electronic transfer function of the FETs with the attached cell. The resulting frequency spectrum was used to investigate the surface adhesion of individual HEK293 cells. We applied different chemical treatments with either the serinpeptidase trypsin or the ionophor amphotericin B (AmpB). Binding studies can be realized by a time-dependent readout of the lock-in amplifier at a constant frequency. We observed cell detachment upon trypsin activity as well as membrane decomposition induced by AmpB. The results were interpreted in terms of an equivalent electrical circuit model of the complete system. The presented method could in future be applied to monitor more relevant biomedical manipulations of individual cells. Due to the utilization of the silicon technology, our method could be easily up-scaled to many output channels for high throughput pharmacological screening.
Background and Objectives
Immunoglobulin (Ig) G1 plays an important role in the adaptive immune response. Kgp, a lysine‐specific cysteine protease from Porphyromonas gingivalis, specifically ...hydrolyses IgG1 heavy chains. The purpose of this study was to examine whether cleavage of IgG1 occurs in gingival crevicular fluid (GCF) in vivo, and whether there is any association with the presence of Porphyromonas gingivalis and other periodontopathogens.
Material and Methods
GCF was obtained from nine patients with aggressive periodontitis, nine with chronic periodontitis and five periodontally healthy individuals. The bacterial loads of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Treponema denticola, Prevotella intermedia and Tannerella forsythia were analysed by real‐time polymerase chain reaction, and the presence and cleavage of IgG1 and IgG2 were determined using Western blotting. Kgp levels were measured by ELISA.
Results
Cleaved IgG1 was identified in the GCF from 67% of patients with aggressive periodontitis and in 44% of patients with chronic periodontitis. By contrast, no cleaved IgG1 was detectable in healthy controls. No degradation of IgG2 was detected in any of the samples, regardless of health status. Porphyromonas gingivalis was found in high numbers in all samples in which cleavage of IgG1 was detected (P < 0.001 compared with samples with no IgG cleavage). Furthermore, high numbers of Tannerella forsythia and Prevotella intermedia were also present in these samples. The level of Kgp in the GCF correlated with the load of Porphyromonas gingivalis (r = 0.425, P < 0.01). The presence of Kgp (range 0.07–10.98 ng/mL) was associated with proteolytic fragments of IgG1 (P < 0.001). However, cleaved IgG1 was also detected in samples with no detectable Kgp.
Conclusion
In patients with periodontitis, cleavage of IgG1 occurs in vivo and may suppress antibody‐dependent antibacterial activity in subgingival biofilms especially those colonized by Porphyromonas gingivalis.
A central feature of the evolution of large software systems is that change-which is necessary to add new functionality, accommodate new hardware, and repair faults-becomes increasingly difficult ...over time. We approach this phenomenon, which we term code decay, scientifically and statistically. We define code decay and propose a number of measurements (code decay indices) on software and on the organizations that produce it, that serve as symptoms, risk factors, and predictors of decay. Using an unusually rich data set (the fifteen-plus year change history of the millions of lines of software for a telephone switching system), we find mixed, but on the whole persuasive, statistical evidence of code decay, which is corroborated by developers of the code. Suggestive indications that perfective maintenance can retard code decay are also discussed.
Objective
A controlled clinical trial was conducted to evaluate the effects of oral prophylaxis on halitosis‐associated, immunological and microbiological parameters.
Methods
Thirty subjects were ...included in this controlled clinical trial (patients with generalized chronic periodontitis and controls without clinical attachment loss; each n = 15). Before oral prophylaxis and 14 days after (including tongue cleaning) volatile sulphur compounds (VSC), organoleptic scores and a tongue coating index were evaluated. The levels of IL‐1β, IL‐8, IL‐10 and MMP‐8 were measured in GCF, and also major periodontal pathogens were detected. Data were statistically analysed using anova and paired t‐test.
Results
Supragingival plaque and calculus removal with combined tongue cleaning was able to reduce significantly (P < 0.05) the VSC values in both groups (no significant differences between both groups). Two weeks after periodontal debridement, the VSC values were observed in the periodontitis group, but not in the control group, similar to the baseline values. The difference between the groups was statistically significant (P < 0.05). Only a repeated prophylaxis session in the periodontitis group was able to reduce VSC values significantly in comparison with baseline (P < 0.05). Organoleptic scores (10 and 30 cm) were significantly different (P < 0.05) between both groups before and after the treatment. Periodontal pathogens and host‐derived markers were not significantly affected by a single prophylaxis session.
Conclusions
Oral prophylaxis may result in a significant decrease in VSC values. However, in periodontal diseases, a more complex treatment seems to be necessary.
Summary
We have previously shown that benzamidine‐type compounds can inhibit the activity of arginine‐specific cysteine proteinases (gingipains HRgpA and RgpB); well‐known virulence factors of ...Porphyromonas gingivalis. They also hinder in vitro growth of this important periodontopathogenic bacterium. Apparently growth arrest is not associated with their ability to inhibit these proteases, because pentamidine, which is a 20‐fold less efficient inhibitor of gingipain than 2,6‐bis‐(4‐amidinobenzyl)‐cyclohexanone (ACH), blocked P. gingivalis growth far more effectively. To identify targets for benzamidine‐derived compounds other than Arg‐gingipains, and to explain their bacteriostatic effects, P. gingivalis ATCC 33277 and P. gingivalis M5‐1‐2 (clinical isolate) cell extracts were subjected to affinity chromatography using a benzamidine–Sepharose column to identify proteins interacting with benzamidine. In addition to HRgpA and RgpB the analysis revealed heat‐shock protein GroEL as another ligand for benzamidine. To better understand the effect of benzamidine‐derived compounds on P. gingivalis, bacteria were exposed to benzamidine, pentamidine, ACH and heat, and the expression of gingipains and GroEL was determined. Exposure to heat and benzamidine‐derived compounds caused significant increases in GroEL, at both the mRNA and protein levels. Interestingly, despite the fact that gingipains were shown to be the main virulence factors in a fertilized egg model of infection, mortality rates were strongly reduced, not only by ACH, but also by pentamidine, a relatively weak gingipain inhibitor. This effect may depend not only on gingipain inhibition but also on interaction of benzamidine derivatives with GroEL. Therefore these compounds may find use in supportive periodontitis treatment.
Objectives: The objective of the study was to evaluate the in vitro activity of ciprofloxacin, gatifloxacin and moxifloxacin against 16 Porphyromonas gingivalis strains. Methods: MICs of the ...quinolones were established by Etest and the agar dilution technique. Experiments focused on determination of the spontaneous mutation rate and the induction of resistant strains, using 0.25-fold MIC of antibiotic. Fragments of gyrA and gyrB as well as of parC were sequenced. Results: Moxifloxacin and gatifloxacin had very low MIC values. Subinhibitory concentrations of the fluoroquinolones rapidly induced mutations. The spontaneous mutation rate was strain- and quinolone-dependent; the lowest rate was encountered after moxifloxacin. The predicted serum concentrations of the quinolones were bactericidal to wild-type strains, but 100 mg/L of each tested quinolone was insufficient to kill a mutant exhibiting moderate resistance. Often the mutants exhibited high resistance to ≥32 mg/L. All these mutants bore a Ser-83→Phe substitution in GyrA. Conclusions: DNA gyrase is the primary target of fluoroquinolones in P. gingivalis. In terms of the achievable level in the gingival fluid and the MICs, moxifloxacin might prevent the development of resistance and may be an alternative in the antibiotic treatment of P. gingivalis-associated periodontitis.
Visual discovery and analysis Eick, S.G.
IEEE transactions on visualization and computer graphics,
2000-Jan.-March, 2000-01-00, 20000101, Letnik:
6, Številka:
1
Journal Article
Recenzirano
We have developed a flexible software environment called ADVIZOR for visual information discovery. ADVIZOR complements existing assumptive-based analyses by providing a discovery-based approach. ...ADVIZOR consists of five parts: a rich set of flexible visual components, strategies for arranging the components for particular analyses, an in-memory data pool, data manipulation components, and container applications. Working together, ADVIZOR's architecture provides a powerful production platform for creating innovative visual query and analysis applications.
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