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| 2. |
- Höglund Åberg, Carola, 1958-
(författare)
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Exotoxins of Aggregatibacter actinomycetemcomitans and periodontal attachment loss in adolescents
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aggregatibacter actinomycetemcomitans is an oral bacterium that is mainly associated with aggressive forms of periodontitis, which most often starts at an early age. Amongst the virulence factors of A. actinomycetemcomitans, two exotoxins, the leukotoxin (LtxA) and the cytolethal distending toxin (Cdt), are suggested to play an important role in the pathogenicity of aggressive periodontitis. There is also a genetic diversity of the different strains of A. actinomycetemcomitans, and a variation in the ability of different strains to express and release exotoxins has been suggested. Of the different genotypes of A. actinomycetemcomitans, the highly leukotoxic JP2 genotype, which is prevalent in individuals of African origin, seems to be the genotype that is most strongly associated with localized aggressive periodontitis.This thesis is built upon studies of a West African adolescent population. The aim was to study the virulence characteristics of A. actinomycetemcomitans genotypes with a specific focus on the LtxA and the Cdt in relation to the progression of attachment loss (AL). The specific aim was first, to investigate cross-sectionally the presence of the JP2 and non-JP2 genotypes of A. actinomycetemcomitans in relation to the prevalence of AL and then prospectively to assess the progression of AL in a Ghanaian adolescent population. Second, in clinical isolates of A. actinomycetemcomitans obtained from the participants of the study, the serotypes and the virulence characteristics related to the two exotoxins were studied and associated with the progression of AL at the individual level.In Paper I, based on the study population consisting of 500 adolescents (mean age 13.2 years; SD ±1.5), it was shown that the overall carrier rate of A. actinomycetemcomitans was high (54.4%) and that the presence of this bacterium was associated with AL ≥ 3 mm. The JP2 genotype was prevalent (8.8%) in this population. In Paper II, 397 (79.4%) of the study participants were periodontally examined again at a 2-year follow-up. The presence of the JP2 genotype of A. actinomycetemcomitans in subgingival plaque was strongly associated with the progression of AL. This study also provided support for an enhanced estimated risk (odds ratio, OR=3.4), though less pronounced, for the progression of AL in individuals positive for the non-JP2 genotypes of A. actinomycetemcomitans.In Paper III, all three cdt genes (a, b and c) were detected in 79% of the examined A. actinomycetemcomitans isolates, all of which expressed an active toxin. The distribution of the cdt genes showed a serotype-dependent pattern. In particular, the presence of the b serotypes (both JP2 and non-JP2 genotypes) was associated with the disease progression, whereas the expression of Cdt was not particularly related to the disease progression. In Paper IV, it was shown that the presence of of A. actinomycetemcomitans isolates with high leukotoxicity, also those of the non-JP2 genotypes of A. actinomycetemcomitans, were associated with an increased risk of the progression of AL in relation to the reference group. The main proportion of the serotype b isolates was distributed in the category of highly leukotoxic isolates. The analyses of the non-JP2 genotypes of serotype b indicated a diversity linked to the level of leukotoxicity.In conclusion, A. actinomycetemcomitans in general was associated with the progression of AL. Individuals with an increased risk of developing progression of AL mainly harboured isolates of A. actinomycetemcomitans with a high leukotoxicity, which suggests that the LtxA is an important virulence factor. Of the two exotoxins, the pathogenic potential was mainly associated with the LtxA, while the role of the Cdt is unclear.
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- Klinge, Björn, et al.
(författare)
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Peri-implant tissue destruction : The Third EAO Consensus Conference 2012
- 2012
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Ingår i: Clinical Oral Implants Research. - : John Wiley & Sons. - 0905-7161 .- 1600-0501. ; 23:Suppl 6, s. 108-110
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The task of this working group was to update the existing knowledge base regarding the prevalence of peri-implant tissue destruction, the role of occlusal overload, and the outcome of non-surgical and surgical treatment.MATERIALS AND METHODS: The literature was systematically searched and critically reviewed. Four manuscripts were presented in key areas deemed to be essential for the current understanding of the magnitude of the clinical entity peri-implantitis. The role of overload as an etiological component was reviewed. Also available data on the results from non-surgical and surgical interventions for the control of tissue destruction were presented.RESULTS: The consensus statements following plenary session approval, clinical implications, and directions for future research based on the group discussions are presented in this article. The results and conclusions of the systematic review process are presented by the respective authors in the subsequent papers.
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| 4. |
- Klinge, Björn, et al.
(författare)
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Peri-implant tissue destruction : The Third EAO Consensus Conference 2012
- 2012
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Ingår i: Clinical Oral Implants Research. - : Blackwell Munksgaard. - 0905-7161 .- 1600-0501. ; 23:Suppl 6, s. 108-110
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The task of this working group was to update the existing knowledge base regarding the prevalence of peri-implant tissue destruction, the role of occlusal overload, and the outcome of non-surgical and surgical treatment. MATERIALS AND METHODS: The literature was systematically searched and critically reviewed. Four manuscripts were presented in key areas deemed to be essential for the current understanding of the magnitude of the clinical entity peri-implantitis. The role of overload as an etiological component was reviewed. Also available data on the results from non-surgical and surgical interventions for the control of tissue destruction were presented. RESULTS: The consensus statements following plenary session approval, clinical implications, and directions for future research based on the group discussions are presented in this article. The results and conclusions of the systematic review process are presented by the respective authors in the subsequent papers.
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| 6. |
- Mapelli, Valeria, 1978, et al.
(författare)
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Viability Study of the Use of Cast Iron Open Cell Foam as Microbial Fuel Cell Electrodes
- 2013
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Ingår i: Advanced Engineering Materials. - : Wiley. - 1527-2648 .- 1438-1656. ; 15:3, s. 112-117
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Tidskriftsartikel (refereegranskat)abstract
- Nowadays, the development of new green technologies has been promoted worldwide both by public andprivate institutions. In this context the research on microbial fuel cells (MFC) represents a promisingalternative to carbon based energy sources. Unfortunately, this technology has been always affected by too lowcurrent density output for allowing an intensive application in the industrial and civil field. The study dealswith this limitation and focuses on the implementation of metallic sponges, specifically cast iron based, aselectrodes, aiming at increasing the exposed surface and thus the current density at the MFC anode. Cast ironwas selected because of its low toxicity for the microorganisms, however its high melting point carries severalproblems for the manufacture process. Parallel to this, the realization of electrodes using foamed metals impliesfurther issues related to the generation of correct pore size distribution and adequate bacterial activity. Forinstance, the metal foams are expected to be open-cell type, so that there can be an efficientmass transport alsoto the inner regions of the electrode. In order to control these parameters the metal sponges are produced byinfiltration of cast iron on ceramic beds. Combining previous data with themeasurements of power generationefficiency the authors conclude the study attempting to design MFCs with metal foamed electrodes.
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| 7. |
- Mombelli, Davide, et al.
(författare)
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Performance of Metal Foams as MFC Electrodes and Characterization of Waste Streams from Pulp and Paper plants in Bioelectrochemical Systems
- 2012
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Ingår i: Communication in Agricultural and Applied Sciences, Ghent University. ; 77:2, s. 129-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Optimization of electrode structure and materials is a subject taken into high consideration to improve the performance of microbial fuel cell (MFC) systems. In this work we show the use of novel electrodes made of metal alloys with a peculiar foam structure. The foam structure of the electrodes, realized according to a proprietary process, is intended to increase the electrode surface available to the microorganisms for the formation of the biofilm. Cast iron (GS800) and stainless steel (304) foams have been used as electrodes in MFC systems run with pure culture of Shewanella oneidensis. In general, foam electrodes showed better performance compared to the massive ones, in terms of current density at the anode. Metal foams with different porosities (i.e. 10, 20 and 30 pores per inch) were compared, showing that the pore density is a critical feature, clearly influencing the overall MFC output and the kinetics of the voltage generation throughout the run. These differences were potentially related to differences in the mass transfer and in the dynamics of the anode colonization by S. oneidensis, which were both affected by the varying porosities.Furthermore, MFC with stainless steel electrodes performed better than the ones using cast iron electrodes, most probably due to changes occurring on the cast iron surface affected by oxidation and corrosion phenomena.Concomitantly to MFC experiments aiming to test metal foam electrodes, we performed a study on the possible use of waste streams from a Swedish pulp and paper plant, exploiting the endogenous microbial populations present in the stream. Analysis of the chemical composition of the waste stream and of the microbial populations thriving in this environment was performed and followed by the analysis of dynamic changes occurring within a bioelectrochemical system. This exploratory study on the use of waste streams from pulp and paper plants aimed to set the basis for a future integration of bioelectrochemical systems into a wider biorefinery concept.
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| 8. |
- Mombelli, Davide, et al.
(författare)
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Viability study of the use of cast iron open cell foam as microbial fuel cell electrodes.
- 2011
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Ingår i: MetFoam2011, Sept. 18-21 2011, BEXCO, Busan, Korea.
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Konferensbidrag (refereegranskat)abstract
- Nowadays, the development of new green technologies has been promoted worldwide both by public and private institutions. In this context the research on microbial fuel cells (MFC) represents a promising alternative to carbon based energy sources. Unfortunately, this technology has been always affected by too low current density for allowing an intensive application in the industrial and civil field. The study deals with this limitation and focuses on the implementation of metallic foams, specifically cast iron based, as electrodes, increasing the exposed surface and thus the activity of the bacterial population. The pig iron was selected because of its low toxicity for the microorganisms and their metabolism, however its high melting point carries several problems for the manufacture process. Parallel to this, the realization of electrodes using foamed metals implies further issues related to the generation of correct pores size distribution and adequate bacterial activity. For instance, the metal foams are expected to be open-cell type, so that the mass transport might reach also the inner regions. In order to control these parameters the metal foams are produced by infiltration of cast iron on ceramic beds. Combining the previous data with the measurements of power generation efficiency the authors conclude the study attempting to design MFCs with metal foamed electrodes.
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| 9. |
- Sanz, Mariano, et al.
(författare)
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Clinical research on peri-implant diseases : consensus report of Working Group 4.
- 2012
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Ingår i: Journal of Clinical Periodontology. - 0303-6979 .- 1600-051X. ; 39:Suppl 12, s. 202-6
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Two systematic reviews have evaluated the quality of research and reporting of observational studies investigating the prevalence of, the incidence of and the risk factors for peri-implant diseases and of experimental clinical studies evaluating the efficacy of preventive and therapeutic interventions.MATERIALS AND METHODS: For the improvement of the quality of reporting for both observational and experimental studies, the STROBE and the Modified CONSORT recommendations were encouraged.RESULTS: To improve the quality of research in peri-implant diseases, the following were recommended: the use of unequivocal case definitions; the expression of outcomes at the subject rather than the implant level; the implementation of study validation tools; the reporting of potential sources of bias; and the use of appropriate statistical methods.CONCLUSIONS: In observational studies, case definitions for peri-implantitis were agreed. For risk factor determination, the progressive use of cross-sectional and case-control studies (univariate analyses), to prospective cohorts (multilevel modelling for confounding), and ultimately to intervention studies were recommended. For preventive and interventional studies of peri-implant disease management, parallel arm RCTs of at least 6-months were encouraged. For studies of non-surgical and surgical management of peri-implantitis, the use of a composite therapeutic end point was advocated. The development of standard control therapies was deemed essential.
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| 10. |
- Sanz, Mariano, et al.
(författare)
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Clinical research on peri-implant diseases : consensus report of Working Group 4.
- 2012
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Ingår i: Journal of Clinical Periodontology. - : Blackwell Munksgaard. - 0303-6979 .- 1600-051X. ; 39:Suppl 12, s. 202-6
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Two systematic reviews have evaluated the quality of research and reporting of observational studies investigating the prevalence of, the incidence of and the risk factors for peri-implant diseases and of experimental clinical studies evaluating the efficacy of preventive and therapeutic interventions. MATERIALS AND METHODS: For the improvement of the quality of reporting for both observational and experimental studies, the STROBE and the Modified CONSORT recommendations were encouraged. RESULTS: To improve the quality of research in peri-implant diseases, the following were recommended: the use of unequivocal case definitions; the expression of outcomes at the subject rather than the implant level; the implementation of study validation tools; the reporting of potential sources of bias; and the use of appropriate statistical methods. CONCLUSIONS: In observational studies, case definitions for peri-implantitis were agreed. For risk factor determination, the progressive use of cross-sectional and case-control studies (univariate analyses), to prospective cohorts (multilevel modelling for confounding), and ultimately to intervention studies were recommended. For preventive and interventional studies of peri-implant disease management, parallel arm RCTs of at least 6-months were encouraged. For studies of non-surgical and surgical management of peri-implantitis, the use of a composite therapeutic end point was advocated. The development of standard control therapies was deemed essential.
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