| 1. |
- Bang, Charlotte Sahlberg, 1967-, et al.
(författare)
-
Multiresistant uropathogenic extended-spectrum β-lactamase (ESBL)-producing Escherichia coli are susceptible to the carbon monoxide releasing molecule-2 (CORM-2).
- 2014
-
Ingår i: Microbial Pathogenesis. - London : Elsevier. - 0882-4010 .- 1096-1208. ; 66, s. 29-35
-
Tidskriftsartikel (refereegranskat)abstract
- Carbon monoxide (CO) releasing molecules (CO-RMs) have been shown to inhibit growth of commensal Escherichia coli (E. coli). In the present study we examined the effect of CORM-2 on uropathogenic E. coli (UPEC) that produces extended-spectrum β-lactamase (ESBL). Viability experiments showed that CORM-2 inhibited the growth of several different ESBL-producing UPEC isolates and that 500 μM CORM-2 had a bactericidal effect within 4 h. The bactericidal effect of CORM-2 was significantly more pronounced than the effect of the antibiotic nitrofurantoin. CORM-2 demonstrated a low level of cytotoxicity in eukaryotic cells (human bladder epithelial cell line 5637) at the concentrations and time-points where the antibacterial effect was obtained. Real-time RT-PCR studies of different virulence genes showed that the expression of capsule group II kpsMT II and serum resistance traT was reduced and that some genes encoding iron acquisition systems were altered by CORM-2. Our results demonstrate that CORM-2 has a fast bactericidal effect against multiresistant ESBL-producing UPEC isolates, and also identify some putative UPEC virulence factors as targets for CORM-2. CO-RMs may be candidate drugs for further studies in the field of finding new therapeutic approaches for treatment of uropathogenic ESBLproducing E. coli.
|
|
| 2. |
- Bang, Charlotte Sahlberg, 1967-, et al.
(författare)
-
The antibacterial effect of nitric oxide against ESBL-producing uropathogenic E-coli is improved by combination with miconazole and polymyxin B nonapeptide
- 2014
-
Ingår i: BMC Microbiology. - London : BioMed Central. - 1471-2180. ; 14
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Nitric oxide (NO) is produced as part of the host immune response to bacterial infections, including urinary tract infections. The enzyme flavohemoglobin, coded by the hmp gene, is involved in protecting bacterial cells from the toxic effects of NO and represents a potentially interesting target for development of novel treatment concepts against resistant uropathogenic bacteria. The aim of the present study was to investigate if the in vitro antibacterial effects of NO can be enhanced by pharmacological modulation of the enzyme flavohemoglobin.Results: Four clinical isolates of multidrug-resistant extended-spectrum beta-lactamase (ESBL)-producing uropathogenic E. coli were included in the study. It was shown that the NO-donor substance DETA/NO, but not inactivated DETA/NO, caused an initial growth inhibition with regrowth noted after 8 h of exposure. An hmp-deficient strain showed a prolonged growth inhibition in response to DETA/NO compared to the wild type. The imidazole antibiotic miconazole, that has been shown to inhibit bacterial flavohemoglobin activity, prolonged the DETA/NO-evoked growth inhibition. When miconazole was combined with polymyxin B nonapeptide (PMBN), in order to increase the bacterial wall permeability, DETA/NO caused a prolonged bacteriostatic response that lasted for up to 24 h.Conclusion: An NO-donor in combination with miconazole and PMBN showed enhanced antimicrobial effects and proved effective against multidrug-resistant ESBL-producing uropathogenic E. coli.
|
|
| 3. |
- Demirel, Isak, 1987-
(författare)
-
Uropathogenic Esherichia coli, multidrug-resistance and induction of host defense mechanisms
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Uropathogenic Escherichia coli (UPEC) is the primary cause of urinary tract infection (UTI), which is one of the most common infections in humans. UPEC strains have acquired successful strategies to subvert the host defense and antibiotics to persist in the urinary tract. The main aim of this thesis was to investigate the host defense mechanisms during a UPEC infection in vitro.The results showed that SOCS3, a key regulator of the immune system, was increased in bladder epithelial cells in response to a UPEC infection. In addition, UPEC decreased the phosphorylation of the SOCS3 regulated transcription factor STAT3. Nitric oxide (NO), a host-derived antimicrobial factor was shown to increase the release of IL-6 from renal epithelial cells alone or in combination with UPEC. The induction of IL-6 was mediated by ERK1/2 and p38 MAPK signaling and NO was also shown to attenuate UPEC-induced IL-6 mRNA degradation. Furthermore, extended-spectrum beta-lactamase (ESBL)-producing UPEC isolates were shown to induce higher PMN migration and ROS-production, but lower cytokine secretion from renal epithelial cells than susceptible isolates. Ineffective ceftibuten treatment of ESBL isolates induced bacterial filamentation associated with an increased release of ATP and LPS, with a subsequent enhancement of the ESBL evoked host response.Taken together, the findings show that UPEC can induce SOCS3, a suppressor of host responses and that NO can regulate proinflammatory mediators. In addition, the data suggest that there are differences between ESBL- and non-ESBL-producing isolates ability to evoke a host response. Exposing resistant isolates to ineffective antibiotics was shown to alter the evoked host response.
|
|
| 4. |
- Gärdsback, Magnus, et al.
(författare)
-
Influence of Strain Path on Work Hardening and Texture in an Austenitic Stainless Steel
- 2014
-
Ingår i: THERMEC 2013. - : Trans Tech Publications Inc.. - 9783038350736 ; , s. 2567-2572
-
Konferensbidrag (refereegranskat)abstract
- The effect of strain path on work hardening and texture for a super austenitic stainless steel was investigated using both experiments and modeling. Compression deformation tests by stepwise changing loading direction in two and three dimensions were performed on cubic specimens at room temperature. The results were compared to uniaxial compression with equal accumulative strain, up to 20%, and uniaxial tension with equal final strain, up to 10% elongation of the longest side. The textures in all samples were analyzed using pole figures from EBSD analysis. Because of the high stacking fault energy of this super austenitic stainless steel, the texture was dominated by <110>-fiber texture in the compressive direction for the uniaxial compression, <111>- and <100>-fiber texture in the tensile direction for the uniaxial tensile test, and a combination of all these for the cube deformation. The density of the texture was much weaker for samples where the loading direction altered, if samples with equal accumulated strain were compared. The cube deformation was also modeled using a crystal plasticity model. The crystal plasticity model consists of a representative volume element (RVE) containing crystal grains with random orientations. The Taylor assumption was used for homogenization between the macro-and subscale. The material parameters in the crystal plasticity model were determined by calibration of its macroscopic response to experimental data. The simulated textures correspond rather well to the experimental results, but the work hardening should be completed to take into account kinematic hardening.
|
|
| 5. |
- Kruse, Robert, 1972-, et al.
(författare)
-
IL-8 and global gene expression analysis define a key role of ATP in renal epithelial cell responses induced by uropathogenic bacteria
- 2014
-
Ingår i: Purinergic Signalling Purinergic Signalling. - Dordrect, Netherlands : Springer. - 1573-9538 .- 1573-9546. ; 10:3, s. 499-508
-
Tidskriftsartikel (refereegranskat)abstract
- The recent recognition of receptor-mediated ATP signalling as a pathway of epithelial pro-inflammatory cytokine release challenges the ubiquitous role of the TLR4 pathway during urinary tract infection. The aim of this study was to compare cellular responses of renal epithelial cells infected with uropathogenic Escherichia coli (UPEC) strain IA2 to stimulation with ATP-gamma-S. A498 cells were infected or stimulated in the presence or absence of apyrase, that degrades extracellular ATP, or after siRNA-mediated knockdown of ATP-responding P2Y(2) receptors. Cellular IL-8 release and global gene expression were analysed. Both IA2 and A498 cells per se released ATP, which increased during infection. IA2 and ATP-gamma-S caused a similar to 5-fold increase in cellular release of IL-8 and stimulations performed in the presence of apyrase or after siRNA knockdown of P2Y(2) receptors resulted in attenuation of IA2-mediated IL-8 release. Microarray results show that both IA2 and ATP-gamma-S induced marked changes in gene expression of renal cells. Thirty-six genes were in common between both stimuli, and many of these are key genes belonging to classical response pathways of bacterial infection. Functional analysis shows that 88 biological function-annotated cellular pathways were identical between IA2 and ATP-gamma-S stimuli. Results show that UPEC-induced release of IL-8 is dependent on P2Y(2) signalling and that cellular responses elicited by UPEC and ATP-gamma-S have many identical features. This indicates that renal epithelial responses elicited by bacteria could be mediated by bacteria- or host-derived ATP, thus defining a key role of ATP during infection.
|
|
| 6. |
- Place, Joachim, et al.
(författare)
-
Reflection seismic characterization of the Grängesberg iron deposit and its mining-induced structures, central Sweden
- 2014
-
Konferensbidrag (refereegranskat)abstract
- Reflection seismic investigation has been conducted on the Grängesberg apatite iron deposit. At the timeof closure in 1989, the mine was operated at about 650 m below the surface. Mining activities might beresumed in the next years, which require better understanding of (1) the ore geometry and (2) the faultnetwork which has developed up to the surface from excavated zones at depth. Two E-W orientedreflection lines with a total length of 3.5 km were acquired. The seismic lines intersect the Grängesbergore body and open pit, as well as several of the mining-induced faults. A weight drop mounted on anhydraulic bobcat truck was used as a seismic source; both cabled and wireless receivers were used for thedata recording. Preprocessing of the data first required the cable- and wireless- recorded datasets to bemerged before stacking all data available at each shot point. The dataset exhibits several shallowreflections which are likely to occur on steep lithologic or tectonic structures. Other deeper reflections arerecorded; careful processing will be carried out in order to preserve such events in final stacked sectionsand help with refining the geological model of the area.
|
|
| 7. |
- Önnberg, Anna, 1980-, et al.
(författare)
-
Characterization of CTX-M-producing Escherichia coli by repetitive sequence-based PCR and real-time PCR-based replicon typing of CTX-M-15 plasmids
- 2014
-
Ingår i: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS). - Malden, USA : John Wiley & Sons. - 0903-4641 .- 1600-0463. ; 122:11, s. 1136-1143
-
Tidskriftsartikel (refereegranskat)abstract
- The emergence of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae is a major global concern. CTX-M is the dominating ESBL type worldwide, and CTX-M-15 is the most widespread CTX-M type. The dissemination of CTX-M appears to be in part due to global spread of the Escherichia coli clone O25b-ST131. However, the gene-encoding CTX-M is mainly located on mobile genetic elements, such as plasmids, that also promote the horizontal dissemination of the CTX-M genes. In this study, 152 CTX-M-producing E. coli isolated in 1999-2008 in Örebro County, Sweden, were typed using a commercial repetitive sequence-based PCR (the DiversiLab system), and the prevalence of ST131 was investigated by pabB PCR. Real-time PCR-based plasmid replicon typing was performed on 82 CTX-M-15-producing E. coli isolates. In general, the CTX-M-producing E. coli population was genetically diverse; however, ST131 was highly prevalent (27%), and the dominating clone in our area. The blaCTX -M-15 gene was mainly located on IncF plasmids (69%), but a relatively high proportion of IncI1 plasmids (29%) were also detected among E. coli with diverse rep-PCR patterns, indicating that horizontal transmission of IncI1 plasmids carrying blaCTX -M-15 may have occurred between different E. coli strains.
|
|
| 8. |
- Demirel, Isak, 1987-, et al.
(författare)
-
Comparison of host response mechanisms evoked by extended spectrum beta lactamase (ESBL)- and non-ESBL-producing uropathogenic E. coli
- 2013
-
Ingår i: BMC Microbiology. - London, United Kingdom : BioMed Central. - 1471-2180. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Infections caused by extended spectrum beta-lactamases (ESBL)-producing bacteria have been emerging worldwide and the majority of ESBL-producing E. coli strains are isolated from patients with urinary tracts infections. The purpose of this study was to compare the host-response mechanisms in human polymorphonucleated leukocytes (PMN) and renal epithelial cells when stimulated by ESBL-or non-ESBL-producing uropathogenic E. coli (UPEC) isolates. The host-pathogen interaction of these ESBL-producing strains in the urinary tract is not well studied.Results: The ability of ESBL strains to evoke ROS-production from PMN cells was significantly higher than that of the non-ESBL strains. The growth of ESBL strains was slightly suppressed in the presence of PMN compared to non-ESBL strains after 30 min and 2 h, but the opposite was observed after 5 and 6 h. The number of migrating PMN was significantly higher in response to ESBL strains compared to non-ESBL strains. Stimulation of A498 cells with ESBL strains elicited lower production of IL-6 and IL-8 compared to non-ESBL strains.Conclusion: Significant differences in host-response mechanisms were identified when host cells were stimulated by ESBL-or non-ESBL producing strains. The obtained results on the early interactions of ESBL-producing strains with the host immune system may provide valuable information for management of these infections.
|
|
| 9. |
- Demirel, Isak, et al.
(författare)
-
Expression of suppressor of cytokine signalling 3 (SOCS3) in human bladder epithelial cells infected with uropathogenic Escherichia coli
- 2013
-
Ingår i: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS). - : Wiley. - 0903-4641 .- 1600-0463. ; 121:2, s. 158-167
-
Tidskriftsartikel (refereegranskat)abstract
- Suppressor of cytokine signalling (SOCS) proteins inhibit pro-inflammatory signalling mediated by Janus-activated kinase (JAK)-signal transducer and activator of transcription (STAT) pathways. To evade the immune response some pathogens appear to modify the host SOCS proteins. Uropathogenic Escherichia coli (UPEC) are able to subvert the host response evoked by bladder epithelial cells, but the mechanisms are not fully understood. The objective of this study was to investigate whether UPEC can modify the host SOCS and STAT3 response. Real time RT-PCR studies demonstrated an increased SOCS1 and SOCS3 expression in the isolated human bladder epithelial cell lines (RT-4 and 5637) in response to cytokines. UPEC strain IA2 increased SOCS3, but not SOCS1, mRNA levels with a peak at 6h after infection. The increase of SOCS3 was confirmed at the protein level by Western blotting. The UPEC strain IA2 caused a time-dependent decrease in the phosphorylation of STAT3. This study demonstrates that UPEC are able to affect SOCS3 and STAT3 signalling in human uroepithelial cells. The finding that UPEC are able to induce mediators involved in suppression of host cytokine signalling may help to elucidate how UPEC may circumvent the host response during urinary tract infection.
|
|
| 10. |
- Demirel, Isak, 1987-, et al.
(författare)
-
Nitric oxide activates IL-6 production and expression in human renal epithelial cells
- 2012
-
Ingår i: American Journal of Nephrology. - Basel, Switzerland : S. Karger. - 0250-8095 .- 1421-9670. ; 36:6, s. 524-530
-
Tidskriftsartikel (refereegranskat)abstract
- Background/Aims: Increased nitric oxide (NO) production or inducible form of NO synthase activity have been documented in patients suffering from urinary tract infection (UTI), but the role of NO in this infection is unclear. We investigated whether NO can affect the host response in human renal epithelial cells by modulating IL-6 production and mRNA expression. Methods: The human renal epithelial cell line A498 was infected with a uropathogenic Escherichia coli (UPEC) strain and/or the NO donor DETA/NO. The IL-6 production and mRNA expression were evaluated by ELISA and real-time RT-PCR. IL-6 mRNA stability was evaluated by analyzing mRNA degradation by real-time RT-PCR.Results: DETA/NO caused a significant (p < 0.05) increase in IL-6 production. Inhibitors of p38 MAPK and ERK1/2 signaling, but not JNK, were shown to significantly suppress DETA/NO-induced IL-6 production. UPEC-induced IL-6 production was further increased (by 73 ± 23%, p < 0.05) in the presence of DETA/NO. The IL-6 mRNA expression increased 2.1 ± 0.17-fold in response to DETA/NO, while the UPEC-evoked increase was pronounced (20 ± 4.5-fold). A synergistic effect of DETA/NO on UPEC-induced IL-6 expression was found (33 ± 7.2-fold increase). The IL-6 mRNA stability studies showed that DETA/NO partially attenuated UPEC-induced degradation of IL-6 mRNA.Conclusions: NO was found to stimulate IL-6 in renal epithelial cells through p38 MAPK and ERK1/2 signaling pathways and also to increase IL-6 mRNA stability in UPEC-infected cells. This study proposes a new role for NO in the host response during UTI by modulating the transcription and production of the cytokine IL-6.
|
|
