| 1. |
- Volgenant, C. M. C., et al.
(författare)
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Low prevalence of multi-resistant bacteria in undergraduate dental students; an observational case-control multi-centre study in Europe
- 2021
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Ingår i: Journal of Oral Microbiology. - : Informa UK Limited. - 2000-2297. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This study assessed the prevalence of MRSA, ESBL and VRE in students from four dental schools in Europe. Methods: The hand, tongue and nostrils of the students who treated patients (study group) and who did not treat patients (control group) were sampled. After incubation in TSB and subculturing in the presence of 4 mu g/ml oxacillin, positive cultures were identified for Staphylococcus aureus by Mannitol salt agar and agglutination tests. The presence of MRSA was confirmed by specific PCR on the species and on the SSCmec genes. ESBL and VRE were isolated using specific CHROMagar and confirmed using antibiotic sensitivity tests. Results: Of the 879 students who participated in this study (454 students which treated patients, 425 controls) a total of 50 students (5.7%) tested positive for a multi-drug resistant bacterium (MDRB); 13 (1.5%) students tested positive for MRSA, 26 (3.0%) for ESBL and 12 (1.4%) for VRE. No statistically significant differences were found between the students who treated patients compared to the control group for any of the MDRB and study centres, excluding MRSA carriage in the Italian student population. The use of antibiotics the year before sampling, was positively associated with the presence of an MDRB (OR 2.0; 95% Confidence Interval 1.10-3.68; p = 0.02). Conclusion: The risk for MDRB carriage and sequential transmission of MDRB for dental health care students and their patients were acceptably low.
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| 2. |
- Belibasakis, G N, et al.
(författare)
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Cytokine responses of human gingival fibroblasts to Actinobacillus actinomycetemcomitans cytolethal distending toxin.
- 2005
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Ingår i: Cytokine. - : Elsevier BV. - 1043-4666 .- 1096-0023. ; 30:2, s. 56-63
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Tidskriftsartikel (refereegranskat)abstract
- Actinobacillus actinomycetemcomitans is implicated in the pathogenesis of localized aggressive periodontitis, and has the capacity to express a cytolethal distending toxin (Cdt). Gingival fibroblasts (GF) are resident cells of the periodontium, which can express several osteolytic cytokines. The aims of this study were a) to investigate the role of Cdt in A. actinomycetemcomitans-induced expression of osteolytic cytokines and their cognate receptors in GF and b) to determine if the previously demonstrated induction of receptor activator of NFkappaB ligand (RANKL) by A. actinomycetemcomitans is mediated by these pro-inflammatory cytokines or by prostaglandin E(2) (PGE(2)). A. actinomycetemcomitans clearly induced interleukin (IL)-6, IL-1beta, and to a minimal extent, tumor necrosis factor (TNF)-alpha mRNA expression. At the protein level, IL-6 but not IL-1beta or TNF-alpha expression was stimulated. The mRNA expression of the different receptor subtypes recognizing IL-6, IL-1beta and TNF-alpha was not affected. A cdt-knockout strain of A. actinomycetemcomitans had similar effects on cytokine and cytokine receptor mRNA expression, compared to its parental wild-type strain. Purified Cdt stimulated IL-6, but not IL-1beta or TNF-alpha protein biosynthesis. Antibodies neutralizing IL-6, IL-1 or TNF-alpha, and the PGE(2) synthesis inhibitor indomethacin, did not affect A. actinomycetemcomitans-induced RANKL expression. In conclusion, a) A. actinomycetemcomitans induces IL-6 production in GF by a mechanism largely independent of its Cdt and b) A. actinomycetemcomitans-induced RANKL expression in GF occurs independently of IL-1, IL-6, TNF-alpha, or PGE(2).
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| 3. |
- Belibasakis, G N, et al.
(författare)
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The cytolethal distending toxin induces receptor activator of NF-kappaB ligand expression in human gingival fibroblasts and periodontal ligament cells.
- 2005
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Ingår i: Infection and immunity. - 0019-9567 .- 1098-5522. ; 73:1, s. 342-51
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Tidskriftsartikel (refereegranskat)abstract
- Actinobacillus actinomycetemcomitans is associated with localized aggressive periodontitis, a disease characterized by rapid loss of the alveolar bone surrounding the teeth. Receptor activator of NF-kappaB Ligand (RANKL) and osteoprotegerin (OPG) are two molecules that regulate osteoclast formation and bone resorption. RANKL induces osteoclast differentiation and activation, whereas OPG blocks this process by acting as a decoy receptor for RANKL. The purpose of this study was to investigate the effect of A. actinomycetemcomitans on the expression of RANKL and OPG in human gingival fibroblasts and periodontal ligament cells. RANKL mRNA expression was induced in both cell types challenged by A. actinomycetemcomitans extract, whereas OPG mRNA expression remained unaffected. Cell surface RANKL protein was also induced by A. actinomycetemcomitans, whereas there was no change in OPG protein secretion. A cytolethal distending toxin (Cdt) gene-knockout strain of A. actinomycetemcomitans did not induce RANKL expression, in contrast to its wild-type strain. Purified Cdt from Haemophilus ducreyi alone, or in combination with extract from the A. actinomycetemcomitans cdt mutant strain, induced RANKL expression. Pretreatment of A. actinomycetemcomitans wild-type extract with Cdt antiserum abolished RANKL expression. In conclusion, A. actinomycetemcomitans induces RANKL expression in periodontal connective tissue cells. Cdt is crucial for this induction and may therefore be involved in the pathological bone resorption during the process of localized aggressive periodontitis.
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| 4. |
- HILDINGSSON, L, et al.
(författare)
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HIGH-SPIN PHENOMENA IN OS-174
- 1992
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Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 545:4, s. 871-888
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states of 174Os have been investigated by means of the (Nd(S, 4n)Os)-Nd-146-S-32-Os-174 reaction using the ESSA30 multidetector system. The decay is dominated by the ground-state positive-parity band, two negative-parity 4- and 5- bands and another band starting at spin 9. Deformed shell-model calculations have been carried out to interpret the observed band structures. The role of the strongly shape-driving, non-aligned, pi-h9/2 configuration in the low-spin region of the ground-state band is discussed. The first band crossing is interpreted as due to the nu-i13/2 alignment. The two lowest side-bands are understood in terms of coupling to octupole excitations.
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| 5. |
- Pontika, E. C., et al.
(författare)
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Aeroengines : Multi-platform application for aero engine simulation and compressor map operating point prediction
- 2019
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Ingår i: Proceedings of the ASME Turbo Expo. - : American Society of Mechanical Engineers (ASME). - 9780791858677
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Konferensbidrag (refereegranskat)abstract
- This paper presents the development of AeroEngineS (Aircraft Engine Simulation), a multi-platform app with graphical user interface for aero engine simulation and compressor map operating point prediction. Gas turbine performance simulation is a crucial part of the design process. It provides information about the required operating conditions of all the components and the overall performance of the engine so that engineers can determine whether the current engine configuration meets the performance requirements. Some gas turbine simulation programs have been developed in the last decades, however, there was a lack of an open-source, lightweight, user-friendly, but still very accurate, application which would be easily accessible from all platforms. AeroEngineS can be used as a user-friendly preliminary design tool, since, during this design phase, details about the geometry are not known yet. The main aim is to calculate simply and quickly the basic parameters of the thermodynamic cycle and the performance, in order to determine which design is able to meet the required specifications. AeroEngineS constitutes a free and simple app which can primarily serve educational purposes as it is easily accessible by students from any platform to assist them in aero engine technology courses. Secondarily, it has the potential to be used even by engineers as a quick tool accessible from all devices. The app consists of two basic stand-alone functions. The first function is aero engine simulation at Design Point which solves thermodynamic calculations. The second function is compressor map operating point prediction using a novel method of combining scaling techniques and Artificial Neural Networks.
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