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- Wilsson, Åsa, 1966-
(författare)
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On the interaction between human neutrophils and Staphylococcus aureus
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Intracellular free calcium is a key second messenger and has been shown to regulate several crucial functions in human neutrophils. The results show that a rise in [Ca2+], is an absolute requirement for efficient killing of serum-opsonized Staphylococcus aureus by human neutrophils. The reduced killing in the absence of Ca2+ was not due to an inhibited ingestion of the S. aureus bacteria but to impairment of the subsequent production of oxygen radicals.S. aureus is a bacterium which binds to extracellular matrix proteins such as vitronectin. When studying the role of Ca2+ during phagocytosis of S. aureus adherent to vitronectin-coated surfaces, the results show that a rise in [Ca2+], is not a prerequisite for ingestion per se. However, Ca2+ control neutrophil migration on vitronectin, by regulating reversible integrindependent adhesion of the neutrophils.The intracellular signalling events of the neutrophils induced by S. aureus were also evaluated. The results demonstrate that S. aureus induces both priming and apoptosis in the neutrophils. This was restricted to viable and not heat-killed bacteria. During priming tyrosine phosphorylation of PLCγ2 and Syk is increased. In addition, the Src-family protein kinase Lyn is activated as well by these bacteria. Inhibition of these proteins by selective drugs abrogates priming of the neutrophils, indicating that these proteins participate in neutrophil priming. Interaction of neutrophils with S. aureus as well as a S. aureus-derived factor induces apoptosis in the neutrophils, and this is regulated by p38 MAPK.Taken together, this investigation shows that the Ca2+-dependent processing of bacteria by human neutrophils leads to several cellular responses affecting inflammation, such as oxidative activation, tyrosine phosphorylation, priming and apoptosis.
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| 2. |
- Aabenhus, Rune, et al.
(författare)
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First attempt to produce experimental Campylobacter concisus infection in mice
- 2008
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Ingår i: World Journal of Gastroenterology. - : Baishideng Publishing Group Inc.. - 1007-9327. ; 14:45, s. 6954-6959
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To infect mice with atypical Campylobacter concisus (C concisus) for the first time. METHODS: Three separate experiments were conducted in order to screen the ability of five clinical C concisus isolates of intestinal origin and the ATCC 33237 type strain of oral origin to colonize and produce infection in immunocompetent BALB/cA mice. The majority of the BALB/cA mice were treated with cyclophosphamide prior to C concisus inoculation to suppress immune functions. Inoculation of C concisus was performed by the gastric route. RESULTS: C concisus was isolated from the liver, ileum and jejunum of cyclophosphamide-treated mice in the first experiment. No C concisus strains were isolated in the two subsequent experiments. Mice infected with C concisus showed a significant loss of body weight from day two through to day five of infection but this decreased at the end of the first week. Histopathologicalexamination did not consistently find signs of inflammation in the gut, but occasionally microabscesses were found in the liver of infected animals. CONCLUSION: Transient colonization with C concisus was observed in mice with loss of body weight. Future studies should concentrate on the first few days after inoculation and in other strains of mice. (C) 2008 The WJG Press. All rights reserved.
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| 3. |
- Abu Al-Soud, Waleed, et al.
(författare)
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Assessment of PCR-DGGE for the identification of diverse Helicobacter species, and application to faecal samples from zoo animals to determine Helicobacter prevalence.
- 2003
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Ingår i: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 52:9, s. 765-771
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Tidskriftsartikel (refereegranskat)abstract
- Helicobacter species are fastidious bacterial pathogens that are difficult to culture by standard methods. A PCR-denaturing gradient gel electrophoresis (PCR-DGGE) technique for detection and identification of different Helicobacter species was developed and evaluated. The method involves PCR detection of Helicobacter DNA by genus-specific primers that target 16S rDNA and subsequent differentiation of Helicobacter PCR products by use of DGGE. Strains are identified by comparing mobilities of unknown samples to those determined for reference strains; sequence analysis can also be performed on purified amplicons. Sixteen DGGE profiles were derived from 44 type and reference strains of 20 Helicobacter species, indicating the potential of this approach for resolving infection of a single host by multiple Helicobacter species. Some more highly related species were not differentiated whereas in highly heterogeneous species, sequence divergence was observed and more than one PCR-DGGE profile was obtained. Application of the PCR-DGGE method to DNA extracted from faeces of zoo animals revealed the presence of Helicobacter DNA in 13 of 16 samples; a correlation was seen between the mobility of PCR products in DGGE analysis and DNA sequencing. In combination, this indicated that zoo animals are colonized by a wide range of different Helicobacter species; seven animals appeared to be colonized by multiple Helicobacter species. By this approach, presumptive identifications were made of Helicobacter bilis and Helicobacter hepaticus in a Nile crocodile, Helicobacter cinaedi in a baboon and a red panda, and Helicobacter felis in a wolf and a Taiwan beauty snake. All of these PCR products (400 bp) showed 100 % sequence similarity to 16S rDNA sequences of the mentioned species. These results demonstrate the potential of PCR-DGGE-based analysis for identification of Helicobacter species in complex ecosystems, such as the gastrointestinal tract, and could contribute to a better understanding of the ecology of helicobacters and other pathogens with a complex aetiology.
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| 5. |
- Abu Al-Soud, Waleed, et al.
(författare)
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DNA of Helicobacter spp. and common gut bacteria in primary liver carcinoma.
- 2008
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Ingår i: Digestive and Liver Disease. - : Elsevier BV. - 1590-8658. ; 40:2, s. 126-131
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND AIM: Gastric and enteric Helicobacter species have been associated with the pathogenesis of some extragastric diseases. METHODS: We retrospectively investigated the presence of DNA of Helicobacter species in samples of the cancer and the surrounding tumour-free liver tissues of patients with hepatocellular carcinoma (HCC, n=12) and cholangiocarcinoma (CC, n=13). The patients were from an area with low liver cancer incidence and with low hepatitis B and C prevalence. Patients with a benign liver disease (n=24) were included as controls. Paraffin-embedded liver samples were examined by a Helicobacter genus-specific PCR assay as well as group-specific PCR assays for Enterobacteriaceae, Bacteroides, Lactobacillus and Enterococcus. PCR products of positive samples were characterised by denaturing gradient gel electrophoresis (DGGE) and DNA sequencing. RESULTS: PCR assay detected Helicobacter DNA in seven of 12 (58%) and eight of 13 (62%) normal liver tissue specimens from HCC and CC patients, respectively. Two cancer samples from HCC patients were Helicobacter-positive but none of the CC cancers. In the control group, three of 24 (12.5%) patients with a benign liver condition were positive for Helicobacter species (p<0.01 compared to results of tumour-free liver tissue from the cancer patients). DGGE and DNA sequence analysis showed that 90% of the detected PCR products were "H. pylori-like". DNA of some other enteric bacteria was detected in the liver of one cancer patient and one control (4% of all patients). CONCLUSION: The presence of DNA of Helicobacter species in liver specimens, but not of other common gut bacteria, was associated with human hepatic carcinogenesis.
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| 10. |
- Ambalam, Padma, et al.
(författare)
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Bile Enhances Cell Surface Hydrophobicity and Biofilm Formation of Bifidobacteria.
- 2014
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Ingår i: Applied Biochemistry and Biotechnology. - : Springer Science and Business Media LLC. - 1559-0291 .- 0273-2289. ; 172:4, s. 1970-1981
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Tidskriftsartikel (refereegranskat)abstract
- Twenty-four human bifidobacterial strains were analysed for cell surface hydrophobicity (CSH) using a salt aggregation test (SAT) and a Congo red binding (CRB) assay. Three strains were selected for a systematic study on the CSH and biofilm formation: Bifidobacterium breve 46, Bifidobacterium animalis ssp. lactis 8:8 and a reference strain B. animalis ssp. lactis JCM 10602. CRB of the B. breve 46 and B. animalis ssp. lactis JCM 10602 was significantly enhanced (P < 0.05) when grown in deMan-Rogosa-Sharpe cysteine (MRSC) broth supplemented with taurocholic acid (TA) or native porcine bile (PB). An enhanced CSH of the strains grown with PB and gastric mucin correlated with an increased mucin binding and an enhanced biofilm formation in prebiotic oligosaccharide-supplemented cultures. The three strains showed late bile-induced biofilm (72 h) under an anaerobic growth condition, and both B. animalis ssp. lactis strains showed a late bile-induced biofilm formation under aerobic conditions shown by crystal violet staining. These two strains were thus considered to be oxygen tolerant and more robust. Furthermore, enhanced biofilm formation of these robust bifidobacterial strains in the presence of prebiotics may allow for strong colonisation in the gastrointestinal tract when administered to in vivo models as a "synbiotic supplement".
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