| 1. |
- Augustinsson (Nilsdotter-Augustinsson), Åsa, 1962-, et al.
(författare)
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Interaction of staphylococcus epidermidis from infected hip prostheses with neutrophil granulocytes
- 2001
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 33:6, s. 408-412
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on the interaction of Staphylococcus epidermis isolated from granulation tissue covering infected hip prostheses and neutrophil granulocytes. Bacterial strains isolated from normal flora were used as controls. The bacteria were well characterized with routine methods and further characterized with random amplified polymorphic DNA analyses and slime tests. Phagocytosis and chemiluminescence (CL) assays were used in the neutrophil interaction studies. The prostheses strains were ingested to a lesser extent than strains from normal flora (p ≤ 0.001). There was no significant difference between the prostheses strains and the normal flora strains in terms of total CL response. However, the extracellular CL response from the neutrophils was lower in comparison with the normal flora when interacting with the prostheses strains. The results of this study support the notion that S. epidermidis strains isolated from infected hip prostheses have an enhanced capacity to resist phagocytosis and that most of these strains elicit a reduced inflammatory response, measured as the production of extracellular oxidative metabolites from the neutrophils, compared to normal flora.
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| 2. |
- Bäckman, Jenny, 1974-, et al.
(författare)
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Clear-cutting affects the ammonia-oxidising community differently in limed and non-limed coniferous forest soils
- 2004
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Ingår i: Biology and Fertility of Soils. - : Springer Science and Business Media LLC. - 0178-2762 .- 1432-0789. ; 40:4, s. 260-267
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Tidskriftsartikel (refereegranskat)abstract
- The effects of clear-cutting on the ammonia-oxidising bacterial community were studied in the soil of limed and non-limed spruce forest plots located in the central part of southern Sweden. The communities were studied using denaturing gradient gel electrophoresis (DGGE) profiling after polymerase chain reaction (PCR) amplification from total DNA with primers reported to be specific for beta-subgroup ammonia-oxidising bacteria. The bands on the DGGE were sequenced and each unique sequence was interpreted as representing one ammonia-oxidising population. The relative abundance of each population was determined by measuring the fluorescence of the respective DGGE bands. In both limed and non-limed soil, the same two Nitrosospira populations were found, one belonging to cluster 2 (NScl2) and one to cluster 4 (NScl4). However, while NScl4 first appeared a year after the clear-cutting in the non-limed plot, it was present both before and after the cutting in the limed plot. Irrespective of previous liming, clear-cutting caused a shift in the ammonia-oxidiser community, from dominance by the NScl2 population to a community with approximately equal relative abundance of NScl2 and NScl4. In both plots the total size of the community increased after clear-cutting (based on increased DGGE band intensity), most likely due to increased NH4+ availability, but the growth response was faster in the limed plot. Hence, the prior liming increased the responsiveness of the ammonia-oxidisers to the changes caused by cutting. This is the first study to report the effects of clear-cutting on the ammonia-oxidising community, and the results show a clear correlation between increased potential nitrification and a shift in the ammonia-oxidiser community.
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| 3. |
- Hermansson, Anna, et al.
(författare)
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Quantification of ammonia-oxidising bacteria in limed and non-limed acidic coniferous forest soil using real-time PCR
- 2004
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717 .- 1879-3428. ; 36:12, s. 1935-1941
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Tidskriftsartikel (refereegranskat)abstract
- Ammonia-oxidising bacteria (AOB) in limed and non-limed acidic coniferous forest soil were investigated using real-time PCR. Two sites in southern Sweden were studied, 244 Åled and Oxafällan. The primers and probe used earlier appeared to be specific to the 16S rRNA gene of AOB belonging to the β-subgroup of the Proteobacteria [Appl. Environ. Microbiol. 67 (2001) 972]. Plots treated with two different doses of lime, 3 or 6 t ha-1, were compared with non-limed control plots on two occasions during a single growing season. Three different soil depths were analysed to elucidate possible differences in the density of their AOB communities. The only clear effect of liming on the AOB was recorded in the beginning of the growing season at 244 Åled. In samples taken in April from this site, the numbers of AOB were higher in the limed plots than in the control plots. At the end of the growing season the AOB communities were all of a similar size in the different plots at both sites, irrespective of liming. The number of AOB, determined using real-time PCR, ranged between 6×106 and 1×109 cells g-1 soil (dw) at the two sites, and generally decreased with increasing soil depth. The results showed no correlation between community density and potential nitrification. This may indicate a partly inactive AOB community. Furthermore, more than 107 cells g-1 soil (dw) were recorded using real-time PCR in the control plot at 244 Åled, although Bäckman et al. [Soil Biol. Biochem. 35 (2003) 1337] detected no AOB like sequences in the same plots using PCR followed by DGGE. Taken together our results strongly suggest that the primers and probe set used are not well suited for quantifying AOB in acidic forest soils, which is probably due to an insufficient specificity. This shows that it is extremely important to re-evaluate any primers and probe set when used in a new environment. Consideration should be given to the specificity and sensitivity, both empirically and using bioinformatic tools.
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| 4. |
- Hermansson, A, et al.
(författare)
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Quantification of ammonia-oxidizing bacteria in arable soil by real-time PCR
- 2001
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 67:2, s. 972-976
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Tidskriftsartikel (refereegranskat)abstract
- Real-time PCR was used to quantify populations of ammonia-oxidizing bacteria representing the ▀ subdivision of the class Proteobacteria in samples of arable soil, both nitrogen fertilized and unfertilized, from Mellby, Sweden. Primers and probes targeting a 16S ribosomal DNA region of the ammonia-oxidizing bacteria were designed and used. In the fertilized soil there were ~6.2 x 107 ammonia-oxidizing bacteria per g of soil, three times more than the number of bacteria in the unfertilized soil. The lyric efficiency of bead beating in these soils was investigated by using populations of free or loosely attached bacteria, bacteria tightly bound to particles, and bacteria in nonfractionated samples. The shapes of the curves generated in these tests showed that the concentration of template DNA released at various times remained constant after 10 to 100 s of bead beating.
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| 5. |
- Katerov, V, et al.
(författare)
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Streptococcal opacity factor : A family of bifunctional proteins with lipoproteinase and fibronectin-binding activities
- 2000
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Ingår i: Current Microbiology. - : Springer Science and Business Media LLC. - 0343-8651 .- 1432-0991. ; 40:3, s. 149-156
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Tidskriftsartikel (refereegranskat)abstract
- The serum opacity factor (SOF) of Streptococcus pyogenes is a type- specific lipoproteinase of unknown biological significance. We have sequenced the sof gene and characterized the corresponding SOF protein from a strain of type M63. It was found that sof63 is related to sof22 and that, similar to SOF22 [25], SOF63 binds fibronectin. Moreover, we demonstrate opacity factor activity in a Streptococcus dysgalactiae fibronectin-binding protein FnBA that is structurally related to the SOF proteins of S. pyogenes. Sequence analysis of these three SOF proteins showed a unique periodical pattern of conserved and variable regions. The enzymatically active part of SOF63 was localized to the fragment corresponding to the entire set of conserved and variable sequences, while for fibronectin-binding a single repeat in the C terminal part of the protein was sufficient. The results show that streptococcal SOF proteins form a novel family of bifunctional proteins with lipoproteinase and fibronectin-binding activities.
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| 6. |
- Strindhall, Jan, et al.
(författare)
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Variations among clinical isolates of Staphylococcus aureus to induce expression of E-selectin and ICAM-1 in human endothelial cells
- 2002
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Ingår i: FEMS Immunology and Medical Microbiology. - 0928-8244 .- 1574-695X. ; 32:3, s. 227-235
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Tidskriftsartikel (refereegranskat)abstract
- Eighteen clinical isolates of Staphylococcus aureus, nine methicillin-sensitive and nine methicillin-resistant, were investigated for their ability to induce expression of E-selectin and ICAM-1 in human endothelial cells. Upregulation of adhesion molecules varied between isolates; 17 isolates induced expression of E-selectin and 13 of ICAM-1. Some isolates induced a significant expression of E-selectin without stimulation of ICAM-1, whereas the opposite was not found. Bacterial viability was required for induction of the adhesion molecules. The kinetics of ICAM-1 expression in S. aureus-infected cells differed from those stimulated with interleukin-1β (IL-1β). On the other hand, expression of E-selectin was very similar in S. aureus-infected and IL-1β-stimulated cells. There was no correlation between ability of S. aureus to induce expression of cell adhesion molecules, methicillin susceptibility, pulse field gel electrophoresis patterns, biochemical characteristics, phage typing and toxin production.
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