| 1. |
- Kucharíková, S., et al.
(författare)
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Covalent immobilization of antimicrobial agents on titanium prevents Staphylococcus aureus and Candida albicans colonization and biofilm formation
- 2016
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Ingår i: Journal of Antimicrobial Chemotherapy. - : Oxford University Press. - 0305-7453 .- 1460-2091. ; 71:4, s. 936-945
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Biofilm-associated implant infections represent a serious public health problem. Covalent immobilization of antimicrobial agents on titanium (Ti), thereby inhibiting biofilm formation of microbial pathogens, is a solution to this problem. Methods: Vancomycin (VAN) and caspofungin (CAS) were covalently bound on Ti substrates using an improved processing technique adapted to large-scale coating of implants. Resistance of the VAN-coated Ti (VAN-Ti) and CAS-coated Ti (CAS-Ti) substrates against in vitro biofilm formation of the bacterium Staphylococcus aureus and the fungal pathogen Candida albicans was determined by plate counting and visualized by confocal laser scanning microscopy. The efficacy of the coated Ti substrates was also tested in vivo using an adapted biomaterial-associated murine infection model in which control-Ti, VAN-Ti or CAS-Ti substrates were implanted subcutaneously and subsequently challenged with the respective pathogens. The osseointegration potential of VAN-Ti and CAS-Ti was examined in vitro using human bone marrow-derived stromal cells, and for VAN-Ti also in a rat osseointegration model. Results: In vitro biofilm formation of S. aureus and C. albicans on VAN-Ti and CAS-Ti substrates, respectively, was significantly reduced compared with biofilm formation on control-Ti. In vivo, we observed over 99.9% reduction in biofilm formation of S. aureus on VAN-Ti substrates and 89% reduction in biofilm formation of C. albicans on CAS-Ti substrates, compared with control-Ti substrates. The coated substrates supported osseointegration in vitro and in vivo. Conclusions: These data demonstrate the clinical potential of covalently bound VAN and CAS on Ti to reduce microbial biofilm formation without jeopardizing osseointegration.
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| 2. |
- Artin, Ingrid, et al.
(författare)
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Effects of carbon dioxide on neurotoxin gene expression in nonproteolytic Clostridium botulinum type E
- 2008
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 74:8, s. 2391-2397
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Tidskriftsartikel (refereegranskat)abstract
- Carbon dioxide is an antimicrobial gas commonly used in modified atmosphere packaging. In the present study, the effects of carbon dioxide on the growth of and neurotoxin production by nonproteolytic Clostridium botulinum type E were studied during the growth cycle. Quantitative reverse transcription-PCR and an enzyme-linked immunosorbent assay were used to quantify expression of the type E botulinum neurotoxin gene (cntE) and the formation of type E neurotoxin. The expression levels of cntE were similar in two strains, with relative expression peaking in the transition between exponential phase and stationary phase. In stationary phase, cntE mRNA expression declined rapidly. The cntE mRNA half-life was calculated to be approximately 9 minutes. Neurotoxin formation occurred in late exponential phase and stationary phase. High carbon dioxide concentrations delayed growth by increasing the lag time and decreasing the maximum growth rate. The effects of carbon dioxide concentration on relative neurotoxin gene expression and neurotoxin formation were significant. Expression of cntE mRNA and the formation of extracellular neurotoxin were twofold higher with a headspace carbon dioxide concentration of 70% (vol/vol) compared to 10% (vol/vol). This finding sheds a new, cautionary light on the potential risks of botulism associated with the use of modified atmosphere packaging. Copyright © 2008, American Society for Microbiology. All Rights Reserved.
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| 3. |
- Caous, Josefin Seth, 1982, et al.
(författare)
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Adhesion of Streptococcus mitis and Actinomyces oris in co-culture to machined and anodized titanium surfaces as affected by atmosphere and pH
- 2013
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Ingår i: BMC Oral Health. - : Springer Science and Business Media LLC. - 1472-6831. ; 13:4
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundWith the rising demand for osseointegrated titanium implants for replacing missing teeth, often in patients with a history of periodontitis, implant-related infections have become an issue of growing concern. Novel methods for treating and preventing implant-associated infections are urgently needed. The aim of this study was to investigate if different pH, atmosphere and surface properties could restrict bacterial adhesion to titanium surfaces used in dental implants.MethodsTitanium discs with machined or anodized (TiUnite™) surface were incubated with a co-culture of Streptococcus mitis and Actinomyces oris (early colonizers of oral surfaces) at pH 5.0, 7.0 and 9.0 at aerobic or anaerobic atmosphere. The adhesion was analysed by counting colony forming (CFU) units on agar and by confocal laser scanning microscopy (CLSM).ResultsThe CFU analysis showed that a pH of 5.0 was found to significantly decrease the adhesion of S. mitis, and an aerobic atmosphere, the adhesion of A. oris. S. mitis was found in significantly less amounts on the anodized surface than the machined surface, while A. oris was found in equal amounts on both surfaces. The CLSM analysis confirmed the results from the CFU count and provided additional information on how the two oral commensal species adhered to the surfaces: mainly in dispersed clusters oriented with the groves of the machined surface and the pores of the anodized surface.ConclusionsBacterial adhesion by S. mitis and A. oris can be restricted by acidic pH and aerobic atmosphere. The anodized surface reduced the adhesion of S. mitis compared to the machined surface; while A. oris adhered equally well to the pores of the anodized surface and to the grooves of the machined surface. It is difficult to transfer these results directly into a clinical situation. However, it is worth further investigating these findings from an in vitro perspective, as well as clinically, to gain more knowledge of the effects acid pH and aerobic atmosphere have on initial bacterial adhesion.
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| 4. |
- Rådström, P., et al.
(författare)
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Pre-PCR processing strategies
- 2003
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Ingår i: PCR Technology: Current Innovations, Second Edition. - : CRC Press. - 9781420040654 - 9780849311840 ; , s. 37-47
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- PCR is particularly valuable for monitoring gene expression, quantifying food-borne pathogens, testing viral load, and also for clinical diagnosis. However, although it can be extremely effective with pure solutions of nucleic acids, its usefulness is limited, in part, by the presence of inhibitory substances. Originating from the samples or from DNA extraction protocols, these can reduce or even block amplification. Although many biological samples have been reported to inhibit PCR amplification, the biochemical and physical mechanisms and identities of many inhibitors remain unclear. © 2004 by CRC Press LLC.
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| 5. |
- Rådström, P., et al.
(författare)
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Strategies for overcoming PCR inhibition
- 2008
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Ingår i: Cold Spring Harbor Protocols. - : Cold Spring Harbor Laboratory. - 1940-3402 .- 1559-6095. ; 3:3
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Tidskriftsartikel (refereegranskat)abstract
- To design a reliable and sensitive conventional or real-time PCR method, it is crucial to select the optimal DNA polymerase(s) and/or amplification facilitator(s) for the chemicals present in the samples during amplification. PCR optimization currentlytends to focus on primer design, buffer, and thermocycling conditions to obtain specific PCR products. The amplification mixture canbe modified by the addition of PCR facilitators or by the choice of the appropriate polymerase to improve proofreading activity, PCR yield, length of amplicon, etc. Modifications can also be made to suit specific applications, such as cloning of PCR products, in vitro mutagenesis, in situ PCP, multiplex PCR, PCR ELISA, or reverse-transcription PCR, However, less effort has been devoted to overcoming the effects of PCR-inhibitory compounds. Ideally, the number of steps required to generate PCR samples should be minimized. The use of appropriate DNA polymerases and amplification facilitators, in combination with optimized sampling techniques reduces the amount of sample handling involved in the analysis. As new PCR technology develops, research inpre-PCR processing is likely to expand in response to the growing demand for rapid, robust, and simple PCR protocols. A future challenge in pre-PCR processing strategies is to design PCR protocols that integrate sampling and DNA amplification in anautomated manner. Furthermore, to monitor PCR performance in the presence of biological compounds, mathematical models are required for the objective interpretation of PCR results. Once the validation parameters of the PCR assay of interest have been studied, the specific sample matrix can be characterized with respect to VCR interference. After obtaining this information, pre-PCR processing strategies can be designed to optimize the protocol for a specific sample. Copyright © 2008 by Cold Spring Harbor Laboratory Press.
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