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  • Artikel  (8.062)
  • Blackwell Publishing Ltd
  • American Institute of Physics (AIP)
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  • 1
    Digitale Medien
    Digitale Medien
    Author index (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Indoor air 15 (2005), S. 0 
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    ISSN: 1600-0668
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Architektur, Bauingenieurwesen, Vermessung , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0668.2005.v15_i6_auindex.x
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  • 2
    Digitale Medien
    Digitale Medien
    Subject index (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Indoor air 15 (2005), S. 0 
    Details
    ISSN: 1600-0668
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Architektur, Bauingenieurwesen, Vermessung , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0668.2005.v15_i6_kwdindex.x
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  • 3
    Digitale Medien
    Digitale Medien
    Disulphide trapping of an in vivo energy-dependent conformation of Escherichia coli TonB protein (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: In Escherichia coli, the TonB system transduces the protonmotive force (pmf) of the cytoplasmic membrane to support a variety of transport events across the outer membrane. Cytoplasmic membrane proteins ExbB and ExbD appear to harvest pmf and transduce it to TonB. Experimental evidence suggests that TonB shuttles to the outer membrane, apparently to deliver conformationally stored potential energy to outer membrane transporters. In the most recent model, discharged TonB is then recycled to the cytoplasmic membrane to be re-energized by the energy coupling proteins, ExbB/D. It has been suggested that the carboxy-terminal 75 amino acids of active TonB could be represented by the rigid, strand-exchanged, dimeric crystal structure of the corresponding fragment. In contrast, recent genetic studies of alanine substitutions have suggested instead that in vivo the carboxy-terminus of intact TonB is dynamic and flexible. The biochemical studies presented here confirm and extend those results by demonstrating that individual cys substitution at aromatic residues in one monomeric subunit can form spontaneous dimers in vivo with the identical residue in the other monomeric subunit. Two energized TonBs appear to form a single cluster of 8–10 aromatic amino acids, including those found at opposite ends of the crystal structure. The aromatic cluster requires both the amino-terminal energy coupling domain of TonB, and ExbB/D (and cross-talk analogues TolQ/R) for in vivo formation. The large aromatic cluster is detected in cytoplasmic membrane-, but not outer membrane-associated TonB. Consistent with those observations, the aromatic cluster can form in the first half of the energy transduction cycle, before release of conformationally stored potential energy to ligand-loaded outer membrane transporters. The model that emerges is one in which, after input of pmf mediated through ExbB/D and the TonB transmembrane domain, the TonB carboxy-terminus can form a meta-stable high-energy conformation that is not represented by the crystal structure of the carboxy-terminus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04384.x
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  • 4
    Digitale Medien
    Digitale Medien
    Reticulocyte-binding protein homologue 1 is required for sialic acid-dependent invasion into human erythrocytes by Plasmodium falciparum (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The Apicomplexan parasite responsible for the most virulent form of malaria, Plasmodium falciparum, invades human erythrocytes through mutiple ligand–receptor interactions. Some strains of P. falciparum are sensitive to neuraminidase treatment of the host erythrocyte and these parasites have been termed sialic acid-dependent as they utilize receptors containing sialic acid. In contrast, other strains can efficiently invade neuraminidase-treated erythrocytes and hence are sialic acid-independent. The molecular interactions that allow P. falciparum to differentially utilize receptors for merozoite invasion are not understood. The P. falciparum reticulocyte-binding protein homologue (PfRh or PfRBL) family have been implicated in the invasion process but their exact role is unknown. PfRh1, a member of this protein family, appears to be expressed in all parasite lines analysed but there are marked differences in the level of expression between different strains. We have used targeted gene disruption of the PfRh1 gene in P. falciparum to show that the encoded protein is required for sialic acid-dependent invasion of human erythrocytes. The ΔPfRh1 parasites are able to invade normally; however, they utilize a pattern of ligand–receptor interactions that are more neuraminidase-resistant. Current data suggest a strategy based on the differential function of specific PfRh proteins has evolved to allow P. falciparum parasites to utilize alternative receptors on the erythrocyte surface for evasion of receptor polymorphisms and the host immune system.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04388.x
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  • 5
    Digitale Medien
    Digitale Medien
    Understanding the control of Pseudomonas aeruginosa alginate synthesis and the prospects for management of chronic infections in cystic fibrosis (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Decades of research have been dedicated to the study of the opportunistic pathogen Pseudomonas aeruginosa, a Gram-negative, environmental bacterium that secretes the exopolysaccharide alginate during chronic lung infection of cystic fibrosis (CF) patients. Although P. aeruginosa utilizes a variety of factors to establish a successful infection in the lungs of CF patients, alginate has stood out as one of the best-studied prognostic indicators of chronic lung infection. While the genetics, biosynthesis and regulation of alginate are well understood, questions still remain concerning its role in biofilm development and its potential as a therapeutic target. The purpose of this review is to provide a brief summary of alginate biosynthesis and regulation, and to highlight recent discoveries in the areas of alginate production, biofilm formation and vaccine design. This information is placed in context with a proposed P. aeruginosa infectious pathway, highlighting avenues for the use of existing therapies as well as the potential for novel agents to reduce or eliminate chronic infections in CF patients.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04552.x
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  • 6
    Digitale Medien
    Digitale Medien
    Patterns of nucleosomal organization in the alc regulon of Aspergillus nidulans: roles of the AlcR transcriptional activator and the CreA global repressor (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: We have studied the chromatin organization of three promoters of the alc regulon of Aspergillus nidulans. No positioned nucleosomes are seen in the aldA (aldehyde dehydrogenase) promoter under any physiological condition tested by us. In the alcA (alcohol dehydrogenase I) and alcR (coding for the pathway-specific transcription factor) promoters, a pattern of positioned nucleosomes is seen under non-induced and non-induced repressed conditions. While each of these promoters shows a specific pattern of chromatin restructuring, in both cases induction results in loss of nucleosome positioning. Glucose repression in the presence of inducer results in a specific pattern of partial positioning in the alcA and alcR promoters. Loss of nucleosome positioning depends absolutely on the AlcR protein and it is very unlikely to be a passive result of the induction of transcription. In an alcR loss-of-function background and in strains carrying mutations of the respective AlcR binding sites of the alcA and alcR promoters, nucleosomes are fully positioned under all growth conditions. Analysis of mutant AlcR proteins establishes that all domains needed for transcriptional activation and chromatin restructuring are included within the first 241 residues. The results suggest a two-step process, one step resulting in chromatin restructuring, a second one in transcriptional activation. Partial positioning upon glucose repression shows a specific pattern that depends on the CreA global repressor. An alcR loss-of-function mutation is epistatic to a creA loss-of-function mutation, showing that AlcR does not act by negating a nucleosome positioning activity of CreA.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04559.x
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  • 7
    Digitale Medien
    Digitale Medien
    The unique structure of archaeal ‘hami’, highly complex cell appendages with nano-grappling hooks (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Proteinaceous, hair-like appendages known as fimbriae or pili commonly extend from the surface of prokaryotic cells and serve important functions such as cell adhesion, biofilm formation, motility and DNA transfer. Here we show that a novel group of archaea from cold, sulphidic springs has developed cell surface appendages of an unexpectedly high complexity with a well-defined base-to-top organization. It represents a new class of filamentous cell appendages, for which the term ‘hamus’ is proposed. Each archaeal cell is surrounded by a halo of about 100 hami, which mediate strong adhesion of the cells to surfaces of different chemical composition. The hami are mainly composed of 120 kDa subunits and remained stable in a broad temperature and pH range (0–70°C; 0.5–11.5). Electron microscopy and cryo-electron tomography revealed that the hamus filament possesses a helical basic structure. At periodic distances, three prickles emanate from the filament, giving it the character of industrially produced barbwire. At its distal end the hami carry a tripartite, barbed grappling hook (60 nm in diameter). The architecture of this molecular hook is reminiscent of man-made fishhooks, grapples and anchors. It appears that nature has developed a perfect mechanical nano-tool in the course of biological evolution, which also might prove useful in the field of nanobiotechnology.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04294.x
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  • 8
    Digitale Medien
    Digitale Medien
    Blue light negatively regulates the sexual filamentation via the Cwc1 and Cwc2 proteins in Cryptococcus neoformans (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Cryptococcus neoformans is a heterothallic basidiomycetous yeast that primarily infects immunocompromised individuals. Dikaryotic hyphae resulting from the fusion of the MATa and MATα mating type strains represent the filamentous stage in the sexual life cycle of C. neoformans. In this study we demonstrate that the production of dikaryotic filaments is inhibited by blue light. To study blue light photoresponse in C. neoformans, we have identified and characterized two genes, CWC1 and CWC2, which are homologous to Neurospora crassa wc-1 and wc-2 genes. Conserved domain analyses indicate that the functions of Cwc1 and Cwc2 proteins may be evolutionally conserved. To dissect their roles in the light response, the CWC1 gene deletion mutants are created in both mating type strains. Mating filamentation in the bilateral cross of cwc1 MATa and MATα strains is not sensitive to light. The results indicate that Cwc1 may be an essential regulator of light responses in C. neoformans. Furthermore, overexpression of the CWC1 or CWC2 gene requires light activation to inhibit sexual filamentation, suggesting both genes may function together in the early step of blue light signalling. Taken together, our findings illustrate blue light negatively regulates the sexual filamentation via the Cwc1 and Cwc2 proteins in C. neoformans.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04549.x
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  • 9
    Digitale Medien
    Digitale Medien
    Retrotransposition strategies of the Lactococcus lactis Ll.LtrB group II intron are dictated by host identity and cellular environment (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Group II introns are mobile retroelements that invade their cognate intron-minus gene in a process known as retrohoming. They can also retrotranspose to ectopic sites at low frequency. Previous studies of the Lactococcus lactis intron Ll.LtrB indicated that in its native host, as in Escherichia coli, retrohoming occurs by the intron RNA reverse splicing into double-stranded DNA (dsDNA) through an endonuclease-dependent pathway. However, in retrotransposition in L. lactis, the intron inserts predominantly into single-stranded DNA (ssDNA), in an endonuclease-independent manner. This work describes the retrotransposition of the Ll.LtrB intron in E. coli, using a retrotransposition indicator gene previously employed in our L. lactis studies. Unlike in L. lactis, in E. coli, Ll.LtrB retrotransposed frequently into dsDNA, and the process was dependent on the endonuclease activity of the intron-encoded protein. Further, the endonuclease-dependent insertions preferentially occurred around the origin and terminus of chromosomal DNA replication. Insertions in E. coli can also occur through an endonuclease-independent pathway, and, as in L. lactis, such events have a more random integration pattern. Together these findings show that Ll.LtrB can retrotranspose through at least two distinct mechanisms and that the host environment influences the choice of integration pathway. Additionally, growth conditions affect the insertion pattern. We propose a model in which DNA replication, compactness of the nucleoid and chromosomal localization influence target site preference.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04554.x
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  • 10
    Digitale Medien
    Digitale Medien
    The TyrR regulon (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The TyrR protein of Escherichia coli can act both as a repressor and as an activator of transcription. It can interact with each of the three aromatic amino acids, with ATP and, under certain circumstances, with the C-terminal region of the α-subunit of RNA polymerase. TyrR protein is a dimer in solution but in the presence of tyrosine and ATP it self-associates to form a hexamer. Whereas TyrR dimers can, in the absence of any aromatic amino acids, bind to certain recognition sequences referred to as ‘strong TyrR boxes’, hexamers can bind to extended sequences including lower-affinity sites called ‘weak TyrR boxes’, some of which overlap the promoter. There is no single mechanism for repression, which in some cases involves exclusion of RNA polymerase from the promoter and in others, interference with the ability of bound RNA polymerase to form open complexes or to exit the promoter. When bound to a site upstream of certain promoters, TyrR protein in the presence of phenylalanine, tyrosine or tryptophan can interact with the α-subunit of RNA polymerase to activate transcription. In one unusual case, activation of a non-productive promoter is used to repress transcription from a promoter on the opposite strand. Regulation of individual transcription units within the regulon reflects their physiological function and is determined by the position and nature of the recognition sites (TyrR boxes) associated with each of the promoters. The intracellular levels of the various forms of the TyrR protein are also postulated to be of critical importance in determining regulatory outcomes. TyrR protein remains a paradigm for a regulator that is able to interact with multiple cofactors and exert a range of regulatory effects by forming different oligomers on DNA and making contact with other proteins. A recent analysis identifying putative TyrR boxes in the E. coli genome raises the possibility that the TyrR regulon may extend beyond the well-characterized transcription units described in this review.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04385.x
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  • 11
    Digitale Medien
    Digitale Medien
    Sequential binding of SeqA protein to nascent DNA segments at replication forks in synchronized cultures of Escherichia coli (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: To demonstrate that sequestration A (SeqA) protein binds preferentially to hemimethylated GATC sequences at replication forks and forms clusters in Escherichia coli growing cells, we analysed, by the chromatin immunoprecipitation (ChIP) assay using anti-SeqA antibody, a synchronized culture of a temperature-sensitive dnaC mutant strain in which only one round of chromosomal DNA replication was synchronously initiated. After synchronized initiation of chromosome replication, the replication origin oriC was first detected by the ChIP assay, and other six chromosomal regions having multiple GATC sequences were sequentially detected according to bidirectional replication of the chromosome. In contrast, DNA regions lacking the GATC sequence were not detected by the ChIP assay. These results indicate that SeqA binds hemimethylated nascent DNA segments according to the proceeding of replication forks in the chromosome, and SeqA releases from the DNA segments when fully methylated. Immunofluorescence microscopy reveals that a single SeqA focus containing paired replication apparatuses appears at the middle of the cell immediately after initiation of chromosome replication and the focus is subsequently separated into two foci that migrate to 1/4 and 3/4 cellular positions, when replication forks proceed bidirectionally an approximately one-fourth distance from the replication origin towards the terminus. This supports the translocating replication apparatuses model.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04389.x
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  • 12
    Digitale Medien
    Digitale Medien
    Strange organelles –Plasmodium mitochondria lack a pyruvate dehydrogenase complex (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Our understanding of the Plasmodium mitochondrion and apicoplast has been greatly assisted by the genome sequence project. Sequence data have seeded recent research showing that the apicoplast is  the  site  of  several  anabolic  pathways  including fatty acid synthesis. The discovery of an active apicoplast pyruvate dehydrogenase complex implies this enzyme generates the acetyl-CoA needed for fatty acid synthesis. However, the absence of a corresponding mitochondrial complex suggests that energy generation in Plasmodium is considerably different from pathways described in other eukaryotes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04314.x
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  • 13
    Digitale Medien
    Digitale Medien
    Differential ability of σs and σ70 of Escherichia coli to utilize promoters containing half or full UP-element sites (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The σs subunit of RNA polymerase (RNAP) is the master regulator of the general stress response in Escherichia coli. Nevertheless, the selectivity of promoter recognition by the housekeeping σ70-containing and σ5-containing RNAP holoenzymes (Eσ70 and Eσs respectively) is not yet fully clarified, as they both recognize nearly identical −35 and −10 promoter consensus sequences. In this study, we show that in a subset of promoters, Eσs favours the presence of a distal UP-element half-site, and at the same time is unable to take advantage of a proximal half-site or a full UP-element. This is reflected by the frequent occurrence of distal UP-element half-sites in natural σs-dependent promoters and the absence of proximal half-sites. Eσ70, however, exhibits the opposite preference. The presence of the −35 element is a prerequisite for this differential behaviour. In the absence of the −35 element, half or full UP-element sites play no role in sigma selectivity, but the distal subsite leads to an equivalent, if not greater, transcriptional stimulation than the proximal one for both sigma factors. Finally, experiments using single amino acid substitutions of σs indicate that the foundation for this preference lies in an inability of σs to interact with the a subunit C-terminal domain.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04382.x
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  • 14
    Digitale Medien
    Digitale Medien
    Heterologous expression of Aquifex aeolicus ribosome recycling factor in Escherichia coli is dominant lethal by forming a complex that lacks functional co-ordination for ribosome disassembly (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Recycling the post-termination ribosomal complex requires the co-ordinated effort of the ribosome, ribosome  recycling  factor  (RRF)  and  elongation  factor EF-G. Although Aquifex aeolicus RRF (aaRRF) binds Escherichia coli ribosomes as efficiently as E. coli RRF, the resulting complex is non-functional and dominant lethal in E. coli, even in the presence of homologous A. aeolicus EF-G. These findings suggest that the E. coli post-termination ribosomal complex with aaRRF lacks functional co-ordination with EF-G required for ribosome recycling. A chimeric EF-G (E. coli domains I–III, A. aeolicus domains IV–V) or an A. aeolicus EF-G with distinct mutations in the domain I–II interface could activate aaRRF. Furthermore, novel mutations that localize to one surface of the  L-shape  structure  of  aaRRF  restored  activity  in E. coli. These aaRRF mutations are spatially distinct from mutations previously described and suggest a novel active centre for coupling EF-G's G domain motor action to ribosome disassembly.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04387.x
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  • 15
    Digitale Medien
    Digitale Medien
    cAMP blocks MAPK activation and sclerotial development via Rap-1 in a PKA-independent manner in Sclerotinia sclerotiorum (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Sclerotinia sclerotiorum is a filamentous ascomycete phytopathogen able to infect an extremely wide range of cultivated plants. Our previous studies have shown that increases in cAMP levels result in the impairment of the development of the sclerotium, a highly differentiated structure important in the disease cycle of this fungus. cAMP also inhibits the activation of a S. sclerotiorum mitogen-activated protein kinase (MAPK), which we have previously shown to be required for sclerotial maturation; thus cAMP-mediated sclerotial inhibition is modulated through MAPK. However, the mechanism(s) by which cAMP inhibits MAPK remains unclear. Here we demonstrate that a protein kinase A (PKA)-independent signalling pathway probably mediates MAPK inhibition by cAMP. Expression of a dominant negative form of Ras, an upstream activator of the MAPK pathway, also inhibited sclerotial development and MAPK activation, suggesting that a conserved Ras/MAPK pathway is required for sclerotial development. Evidence from bacterial toxins that specifically inhibit the activity of small GTPases, suggested that Rap-1 or Ras is involved in cAMP action. The Rap-1 inhibitor, GGTI-298, restored MAPK activation in the presence of cAMP, further suggesting that Rap-1 is responsible for cAMP-dependent MAPK inhibition. Importantly, inhibition of Rap-1 is able to restore sclerotial development blocked by cAMP. Our results suggest a novel mechanism involving the requirement of Ras/MAPK pathway for sclerotial development that is negatively regulated by a PKA-independent cAMP signalling pathway. Cross-talk between these two pathways is mediated by Rap-1.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04390.x
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  • 16
    Digitale Medien
    Digitale Medien
    The human malaria parasite Plasmodium falciparum possesses two distinct dihydrolipoamide dehydrogenases (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The Plasmodium falciparum genome contains genes encoding three α-ketoacid dehydrogenase multienzyme complexes (KADHs) that have central metabolic functions. The parasites possess two distinct genes encoding dihydrolipoamide dehydrogenases (LipDH), which are indispensable subunits of KADHs. This situation is reminiscent of that in plants, where two distinct LipDHs are found in mitochondria and chloroplasts, respectively, that are part of the organelle-specific KADHs. In this study, we show by reverse transcription polymerase chain reaction (RT-PCR) that the genes encoding subunits of all three KADHs, including both LipDHs, are transcribed during the erythrocytic development of P. falciparum. Protein expression of mitochondrial LipDH and mitochondrial branched chain α-ketoacid dihydrolipoamide transacylase in these parasite stages was confirmed by Western blotting. The localization of the two LipDHs to the parasite's apicoplast and mitochondrion, respectively, was shown by expressing the LipDH N-terminal presequences fused to green fluorescent protein in erythrocytic stages of P. falciparum and by immunofluorescent colocalization with organelle-specific markers. Biochemical characterization of recombinantly expressed mitochondrial LipDH revealed that the protein has kinetic and physicochemical characteristics typical of these flavo disulphide oxidoreductases. We propose that the mitochondrial LipDH is part of the mitochondrial α-ketoglutarate dehydrogenase and branched chain α-ketoacid dehydrogenase complexes and that the apicoplast LipDH is an integral part of the pyruvate dehydrogenase complex which occurs only in the apicoplast in P. falciparum.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04398.x
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  • 17
    Digitale Medien
    Digitale Medien
    Enteropathogenic Escherichia coli EspG disrupts microtubules and in conjunction with Orf3 enhances perturbation of the tight junction barrier (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: EspG, a secreted effector of enteropathogenic Escherichia coli (EPEC), as well as its homologue Orf3, has been shown to disrupt microtubules (MTs) in fibroblasts and non-polarized epithelial cells. The roles of MTs and the effects of MT disruption in these cell types differ significantly. The aim of this study was to investigate the effects of EspG on polarized, host target intestinal epithelial cells. Immunofluorescent labelling of tubulin showed that EPEC caused progressive fragmentation and loss of the MT network in cells harbouring attached organisms. Immunoblots of proteins extracted from EPEC-infected cells showed a corresponding loss of α-tubulin. Type III secretion system (TTSS)-deficient strains had no effect on MT suggesting TTSS dependence. Mutation of espG, but not espF or map, ablated EPEC's effects on MTs for up to 6 h. Ectopic expression of EspG in HeLa cells caused MT disruption. While deletion of espG alone had no effect on the EPEC-induced decrease in transepithelial electrical resistance (TER), mutation of both espG and orf3 significantly delayed the kinetics of this response. Complementation of the double mutant with espG alone restored the kinetics of TER drop to that of wild type. Herein, we describe a previously unrecognized phenotype for the EPEC effectors EspG and Orf3.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04571.x
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  • 18
    Digitale Medien
    Digitale Medien
    Erwinia chrysanthemi requires a second iron transport route dependent of the siderophore achromobactin for extracellular growth and plant infection (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Full virulence of the pectinolytic enterobacterium Erwinia chrysanthemi strain 3937 depends on the production in planta of the catechol-type siderophore chrysobactin. Under iron-limited conditions, E. chrysanthemi synthesizes a second siderophore called achromobactin belonging to the hydroxy/carboxylate class of siderophore. In this study, we cloned and functionally characterized a 13 kb long operon comprising seven genes required for the biosynthesis (acs) and extracellular release (yhcA) of achromobactin, as well as the gene encoding the specific outer membrane receptor for its ferric complex (acr). The promoter of this operon was negatively regulated by iron. In a fur null mutant, transcriptional fusions to the acsD and acsA genes were constitutively expressed. Band shift assays showed that the purified E. chrysanthemi Fur repressor protein specifically binds in vitro to the promoter region of the acsF gene confirming that the metalloregulation of the achromobactin operon is achieved directly by Fur. The temporal production of achromobactin in iron-depleted bacterial cultures was determined: achromobactin is produced before chrysobactin and its production decreases as that of chrysobactin increases. Pathogenicity tests performed on African violets showed that achromobactin production contributes to the virulence of E. chrysanthemi. Thus, during infection, synthesis of these two different siderophores allows E. chrysanthemi cells to cope with the fluctuations of iron availability encountered within plant tissues. Interestingly, iron transport mediated by achromobactin or a closely related siderophore probably exists in other phytopathogenic bacterial species such as Pseudomonas syringae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04383.x
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  • 19
    Digitale Medien
    Digitale Medien
    Cell size and nucleoid organization of engineered Escherichia coli cells with a reduced genome (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The minimization of a genome is necessary to identify experimentally the minimal gene set that contains only those genes that are essential and sufficient to sustain a functioning cell. Recent developments in genetic techniques have made it possible to generate bacteria with a markedly reduced genome. We developed a simple system for formation of markerless chromosomal deletions, and constructed and characterized a series of large-scale chromosomal deletion mutants of Escherichia coli that lack between 2.4 and 29.7% of the parental chromosome. Combining deletion mutations changes cell length and width, and the mutant cells with larger deletions were even longer and wider than the parental cells. The nucleoid organization of the mutants is also changed: the nucleoids occur as multiple small nucleoids and are localized peripherally near the envelope. Inhibition of translation causes them to condense into one or two packed nucleoids, suggesting that the coupling of transcription and translation of membrane proteins peripherally localizes chromosomes. Because these phenotypes are similar to those of spherical cells, those may be a consequence of the morphological change. Based on the nucleoid localization observed with these mutants, we discuss the cellular nucleoid dynamics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04386.x
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  • 20
    Digitale Medien
    Digitale Medien
    New insertion sequences of Sulfolobus: functional properties and implications for genome evolution in hyperthermophilic archaea (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Analyses of complete genomes indicate that insertion sequences (ISs) are abundant and widespread in hyperthermophilic archaea, but few experimental studies have measured their activities in these hosts. As a way to investigate the impact of ISs on Sulfolobus genomes, we identified seven transpositionally active ISs in a widely distributed Sulfolobus species, and measured their functional properties. Six of the seven were found to be distinct from previously described ISs of Sulfolobus, and one of the six could not be assigned to any known IS family. A type II ‘Miniature Inverted-repeat Transposable Element’ (MITE) related to one of the ISs was also recovered. Rates of transposition of the different ISs into the pyrEF region of their host strains varied over a 250-fold range. The Sulfolobus ISs also differed with respect to target-site selectivity, although several shared an apparent preference for the pyrEF promoter region. Despite the number of distinct ISs assayed and their molecular diversity, only one demonstrated precise excision from the chromosomal target region. The fact that this IS is the only one lacking inverted repeats and target-site duplication suggests that the observed precise excision may be promoted by the IS itself. Sequence searches revealed previously unidentified partial copies of the newly identified ISs in the Sulfolobus tokodaii and Sulfolobus solfataricus genomes. The structures of these fragmentary copies suggest several distinct molecular mechanisms which, in the absence of precise excision, inactivate ISs and gradually eliminate the defective copies from Sulfolobus genomes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04391.x
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  • 21
    Digitale Medien
    Digitale Medien
    The malaria parasite Plasmodium falciparum has only one pyruvate dehydrogenase complex, which is located in the apicoplast (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The relict plastid (apicoplast) of apicomplexan parasites synthesizes fatty acids and is a promising drug target. In plant plastids, a pyruvate dehydrogenase complex (PDH) converts pyruvate into acetyl-CoA, the major fatty acid precursor, whereas a second, distinct PDH fuels the tricarboxylic acid cycle in the mitochondria. In contrast, the presence of genes encoding PDH and related enzyme complexes in the genomes of five Plasmodium species and of Toxoplasma gondii indicate that these parasites contain only one single PDH. PDH complexes are comprised of four subunits (E1α, E1β, E2, E3), and we confirmed four genes encoding a complete PDH in Plasmodium falciparum through sequencing of cDNA clones. In apicomplexan parasites, many nuclear-encoded proteins are targeted to the apicoplast courtesy of two-part N-terminal leader sequences, and the presence of such N-terminal sequences on all four PDH subunits as well as phylogenetic analyses strongly suggest that the P. falciparum PDH is located in the apicoplast. Fusion of the two-part leader sequences from the E1α and E2 genes to green fluorescent protein experimentally confirmed apicoplast targeting. Western blot analysis provided evidence for the expression of the E1α and E1β PDH subunits in blood-stage malaria parasites. The recombinantly expressed catalytic domain of the PDH subunit E2 showed high enzymatic activity in vitro indicating that pyruvate is converted to acetyl-CoA in the apicoplast, possibly for use in fatty acid biosynthesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04407.x
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  • 22
    Digitale Medien
    Digitale Medien
    A kinase for light and time (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The eukaryotic filamentous fungus Neurospora crassa has proven to be a dependable model system for the analysis of light-regulated gene expression and circadian rhythmicity. The molecular basis of the core circadian clock is a transcription/translation-based feedback loop in which a heterodimer of the white-collar 1 (WC-1) and white-collar 2 (WC-2) proteins act as a transcription factor to promote expression of the negative elements in the clock, frq mRNA and FRQ protein. Additionally, WC-1 is a flavoprotein that acts as the primary responder to environmental light and, in conjunction with WC-2, is the major photoreceptor for the clock as well as other light-regulated processes. Protein kinase C acts as a light-dependent regulator of the WC-1 protein.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04546.x
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  • 23
    Digitale Medien
    Digitale Medien
    Respiration metabolism of Group B Streptococcus is activated by environmental haem and quinone and contributes to virulence (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Group B Streptococcus (GBS) is a common constituent of the vaginal microflora, but its transmission to newborns can cause life-threatening sepsis, pneumonia and meningitis. Energy metabolism of this opportunist pathogen has been deduced to be strictly fermentative. We discovered that GBS undergoes respiration metabolism if its environment supplies two essential respiratory components: quinone and haem. Respiration metabolism led to significant changes in growth characteristics, including a doubling of biomass and an altered metabolite profile under the tested conditions. The GBS respiratory chain is inactivated by: (i) withdrawing haem and/or quinone, (ii) treating cultures with a respiration inhibitor or (iii) inactivating the cydA gene product, a subunit of cytochrome bd quinol oxidase, in all cases resulting in exclusively fermentative growth. cydA inactivation reduced GBS growth in human blood and strongly attenuated virulence in a neonatal rat sepsis model, suggesting that the animal host may supply the components that activate GBS respiration. These results suggest a role of respiration metabolism in GBS dissemination. Our findings show that environmental factors can increase the flexibility of GBS metabolism by activating a newly identified respiration chain. The need for two environmental factors may explain why GBS respiration metabolism was not found in previous studies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04555.x
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  • 24
    Digitale Medien
    Digitale Medien
    Defining the role of PfCRT in Plasmodium falciparum chloroquine resistance (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Recent studies have highlighted the importance of a parasite protein referred to as the chloroquine resistance transporter (PfCRT) in the molecular basis of Plasmodium falciparum resistance to the quinoline antimalarials. PfCRT, an integral membrane protein with 10 predicted transmembrane domains, is a member of the drug/metabolite transporter superfamily and is located on the membrane of the intra-erythrocytic parasite's digestive vacuole. Specific polymorphisms in PfCRT are tightly correlated with chloroquine resistance. Transfection studies have now proven that pfcrt mutations confer verapamil-reversible chloroquine resistance in vitro and reveal their important role in resistance to quinine. Available evidence is consistent with the view that PfCRT functions as a transporter directly mediating the efflux of chloroquine from the digestive vacuole.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04556.x
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  • 25
    Digitale Medien
    Digitale Medien
    The gene NCE103 (YNL036w) from Saccharomyces cerevisiae encodes a functional carbonic anhydrase and its transcription is regulated by the concentration of inorganic carbon in the medium (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Carbonic anhydrase (CA) catalyses the rapid interconversion between CO2 and HCO3–. Despite its wide distribution among living organisms, the presence of CA in fungi has been controversially discussed. Using mass spectrometric analysis of 18O exchange from doubly labelled CO2, we were able to measure CA activity in intact cells of Saccharomyces cerevisiae. Intracellular CA activity was lacking in the Δnce103 mutant, indicating that NCE103 encodes a functional CA. This was proven by overexpressing and purification of the NCE103 gene product showing a specific activity of around 6900 units per mg protein. Interestingly, the in vivo CA activity was 10–20 times higher in cells grown on low inorganic carbon (Ci; air containing 0.035% CO2) than in high-Ci cells (grown on 5% CO2). The enhanced CA activity of low-Ci cells was inducible after transferring high-Ci cells to air. Northern blot analysis revealed that that expression of NCE103 is transcriptionally regulated by low Ci which was also demonstrated by fusing the NCE103 promoter to β-galactosidase as a reporter gene. Inactivation of NCE103 results in a high CO2 requiring mutant indicating that a functional CA is an important prerequisite for S. cerevisiae to grow under low-Ci conditions
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04560.x
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  • 26
    Digitale Medien
    Digitale Medien
    Regulation of azole drug susceptibility by Candida albicans protein kinase CK2 (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Fluconazole resistance of the fungal pathogen Candida albicans can arise through several mechanisms, but the responsible genes and pathways are poorly understood. We report here that mutations in CKA2, identified through an insertional mutagenesis screen, confer fluconazole resistance. CKA2 and its homologue CKA1 specify catalytic subunits of protein kinase CK2. Although cka1 mutations have little effect on fluconazole resistance, CKA1 overexpression suppresses the fluconazole resistance of a cka2 mutant. This observation, along with synthetic cka1–cka2 interactions, argues that Cka1p and Cka2p carry out similar functions. cka2 mutants overexpress CDR1 and CDR2, two fluconazole efflux transporter genes, and a cdr1 mutation decreases resistance of a cka2 mutant, as expected if CDR1 and CDR2 overexpression is responsible for fluconazole resistance of the cka2 mutant. The protein phosphatase calcineurin is required for azole tolerance, and we find that the calcineurin inhibitor cyclosporin reverses fluconazole resistance of cka2 mutants. In addition, a mutation in CRZ1, which specifies a homologue of the Saccharomyces cerevisiae transcription factor that is a major target of calcineurin, suppresses fluconazole resistance  of  cka2 mutants.  Expression  analysis  of Cka2p-responsive genes argues that Cka2p and Crz1p act through distinct mechanisms. Several clinical fluconazole-resistant isolates overexpress some Cka2p-responsive genes. We suggest that a Cka2p-dependent regulatory pathway is altered by clinically derived azole resistance mutations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04562.x
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  • 27
    Digitale Medien
    Digitale Medien
    Measure for measure in the control of type III secretion hook and needle length (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Bacterial flagella and injectisomes are supramolecular structures that are responsible for motility and for delivering toxic proteins into the cytosol of eukaryotic cells, respectively. They look very similar to each other. Both systems are called type III secretion pathways, and their components share substantial sequence similarities. One remarkable feature of the type III systems is that the length of their substructure is fairly well controlled by a secretion switching machinery, which consists of at least two proteins, a length control protein and an integral membrane secretion component. Here, we review how and why the length of these structures must be accurately controlled.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04611.x
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  • 28
    Digitale Medien
    Digitale Medien
    A bacterial hormone (the SCB1) directly controls the expression of a pathway-specific regulatory gene in the cryptic type I polyketide biosynthetic gene cluster of Streptomyces coelicolor (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Gamma-butyrolactone signalling molecules are produced by many Streptomyces species, and several have been shown to regulate antibiotic production. In Streptomyces coelicolor A3(2) at least one γ-butyrolactone (SCB1) has been shown to stimulate antibiotic production, and genes encoding proteins that are involved in its synthesis (scbA) and binding (scbR) have been characterized. Expression of these genes is autoregulated by a complex mechanism involving the γ-butyrolactone. In this study, additional genes influenced by ScbR were identified by DNA microarray analysis, and included a cryptic cluster of genes for a hypothetical type I polyketide. Further analysis of this gene cluster revealed that the pathway-specific regulatory gene, kasO, is a direct target for regulation by ScbR. Gel retardation and DNase I footprinting analyses identified two potential binding sites for ScbR, one at −3 to −35 nt and the other at −222 to −244 nt upstream of the kasO transcriptional start site. Addition of SCB1 eliminated the DNA binding activity of ScbR at both sites. The expression of kasO was growth phase regulated in the parent (maximal during transition phase), undetectable in a scbA null mutant, and constitutively expressed in a scbR null mutant. Addition of SCB1 to the scbA mutant restored the expression of kasO, indicating that ScbR represses kasO until transition phase, when presumably SCB1 accumulates in sufficient quantity to relieve kasO repression. Expression of the cryptic antibiotic gene cluster was undetectable in a kasO deletion mutant. This is the first report with comprehensive in vivo and in vitro data to show that a γ-butyrolactone-binding protein directly regulates a secondary metabolite pathway-specific regulatory gene in Streptomyces.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04543.x
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  • 29
    Digitale Medien
    Digitale Medien
    Translation elongation factor EF-Tu is a target for Stp, a serine-threonine phosphatase involved in virulence of Listeria monocytogenes (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Listeria monocytogenes is a pathogen that causes listeriosis, a severe food-borne infection. This bacterium, in order to survive and grow in the multiple conditions encountered in the host and the environment, has evolved a large number of regulatory elements, in particular many signal transduction systems based on reversible phosphorylation. The genome sequence has revealed genes for 16 putative two-component systems, four putative tyrosine phosphatases, three putative serine-threonine kinases and two putative serine-threonine phosphatases. We found that one of the latter genes, stp, encodes a functional Mn2+-dependent serine-threonine phosphatase similar to PPM eukaryotic phosphatases (Mg2+-or Mn2+-dependent protein phosphatase) and is required for growth of L. monocytogenes in a murine model of infection. We identified as the first target for Stp, the elongation factor EF-Tu. Post-translational phosphorylation of EF-Tu had been shown to prevent its binding to amino-acylated transfer RNA as well as to kirromycin, an antibiotic known to inhibit EF-Tu function. Accordingly, an stp deletion mutant is less sensitive to kirromycin. These results suggest an important role for Stp in regulating EF-Tu and controlling bacterial survival in the infected host.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04551.x
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  • 30
    Digitale Medien
    Digitale Medien
    Nck-independent actin assembly is mediated by two phosphorylated tyrosines within enteropathogenic Escherichia coli Tir (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Enteropathogenic Escherichia coli (EPEC) stimulates tyrosine-kinase signalling cascades to trigger localized actin assembly within mammalian cells. During actin ‘pedestal’ formation, the EPEC effector protein Tir is translocated into the plasma membrane, becomes phosphorylated on tyrosine-474 (Y474) and promotes recruitment of the mammalian adaptor protein Nck to efficiently activate N-WASP-Arp2/3-mediated actin polymerization. Tir also triggers localized actin assembly in the absence of Nck, but the Tir sequences involved in this signalling cascade have not been defined. To identify and characterize the phosphotyrosines that contribute to Nck-independent pedestal formation, we investigated the regulation of Tir tyrosine phosphorylation and found that phosphorylation is stimulated by Tir clustering. In addition to Y474, residue Y454 is also phosphorylated, although at lower efficiency. These tyrosines differentially contribute to actin polymerization in a fashion reminiscent of actin ‘tail’ formation mediated by the vaccinia virus envelope protein A36R, which utilizes two similarly spaced phosphotyrosines to recruit the adaptors Nck and Grb2, respectively, in order to stimulate N-WASP. Neither phosphorylated Y454 nor Y474 directly bind Grb2, but Tir derivatives harbouring these residues ultimately recruit N-WASP and Arp2/3 independently of Nck, suggesting that EPEC exploits additional phosphotyrosine-binding adaptors capable of initiating actin assembly.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04558.x
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  • 31
    Digitale Medien
    Digitale Medien
    A truncated H-NS-like protein from enteropathogenic Escherichia coli acts as an H-NS antagonist (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04569.x
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  • 32
    Digitale Medien
    Digitale Medien
    N-terminal signal region of FliK is dispensable for length control of the flagellar hook (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The length of the flagellar hook is regulated; it is 55 ± 6 nm long in Salmonella. Five genes involved in hook-length regulation are fliK, flhB, fliG, fliM and fliN. The last four genes encode structural components of the protein export apparatus in the flagellar base, whereas FliK is soluble and secreted during flagellar assembly. The role of FliK, however, remains ambiguous. We constructed two kinds of FliK variants: N-terminally truncated FliK protein and FliK N-terminally fused with cyan fluorescent protein (CFP-FliK). Both N-terminally truncated FliK missing the first 99 amino acids (aa) and CFP-FliK fusion variants partially complemented a fliK null (polyhook) mutant to produce cells with filaments, allowing cells to swim; the hooks, however, were not normal but were polyhooks. When the N-terminally defective FliK variants were expressed at high levels, the average polyhook length was shortened coming close to the length of the wild-type hook, independently of the sizes of the FliK variants. These FliK variants were not secreted. CFP-FliK fusion proteins were observed to homogeneously distribute in the cytoplasm. We conclude that FliK does not need to be exported to control hook length and is unlikely to be a ruler; instead, we conclude that FliK controls hook length by the timely switching of secretion modes of the flagellar type III secretion system  by  the  FliK  C-terminal  domain,  and  that  the  N-terminal region is dispensable for hook length control.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04615.x
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  • 33
    Digitale Medien
    Digitale Medien
    Regulation of Sin recombinase by accessory proteins (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Sin recombinase from Staphylococcus aureus acts selectively on directly repeated resH sites, assembling an intertwined synapse in which exactly three supercoils are trapped between the points of strand exchange. Resolution requires the two Sin binding sites in resH (site I, where strand exchange occurs, and site II) and a non-specific DNA-bending protein (e.g. Hbsu). We show that a single amino acid substitution in Sin (I100T) is sufficient to relax the normal requirements for site II and Hbsu. Using this hyperactive protein, and the variant recombination site resHAT, we investigate the roles of site II and Hbsu in synapsis and strand exchange. We conclude that Sin bound at site II, and Hbsu, act together to control site I alignment and the topology of the synapse, and to stimulate strand exchange.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04550.x
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  • 34
    Digitale Medien
    Digitale Medien
    Protein kinase C modulates light responses in Neurospora by regulating the blue light photoreceptor WC-1 (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The Neurospora protein kinase C (NPKC) is a regulator of light responsive genes. We have studied the function of NPKC in light response by investigating its biochemical and functional interaction with the blue light photoreceptor white-collar 1 (WC-1), showing that activation of NPKC leads to a significant decrease in WC-1 protein levels. Furthermore, we show that WC-1 and NPKC interact in a light-regulated manner in vivo, and that protein kinase C (PKC) phosphorylates WC-1 in vitro. We designed dominant negative and constitutively active forms of PKC which are able to induce either a large increase of WC-1 protein level or a strong reduction respectively. Moreover, these changes in PKC activity result in an altered light response. As WC-1 is a key component of Neurospora circadian clock and regulates the clock oscillator component FRQ we investigated the effect of NPKC-mutated forms on FRQ levels. We show that changes in PKC activity affect FRQ levels and the robustness of the circadian clock. Together these data identify NPKC as a novel component of the Neurospora light signal transduction pathway that modulates the circadian clock.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04545.x
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  • 35
    Digitale Medien
    Digitale Medien
    Co-regulation of Salmonella enterica genes required for virulence and resistance to antimicrobial peptides by SlyA and PhoP/PhoQ (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Analysis of the transcriptome of slyA mutant Salmonella enterica serovar Typhimurium revealed that many SlyA-dependent genes, including pagC, pagD, ugtL, mig-14, virK, phoN, pgtE, pipB2, sopD2, pagJ and pagK, are also controlled by the PhoP/PhoQ regulatory system. Many SlyA- and PhoP/PhoQ-co-regulated genes have functions associated with the bacterial envelope, and some have been directly implicated in virulence and resistance to antimicrobial peptides. Purified His-tagged SlyA binds to the pagC and mig-14 promoters in regions homologous to a previously proposed ‘SlyA-box’. The pagC promoter lacks a consensus PhoP binding site and does not bind PhoP in vitro, suggesting that the effect of PhoP on pagC transcription is indirect. Stimulation of pagC expression by PhoP requires SlyA. Levels of SlyA protein and mRNA are not significantly changed under low-magnesium PhoP-inducing conditions in which pagC expression is profoundly elevated, however, indicating that the PhoP/PhoQ system does not activate pagC expression by altering SlyA protein concentration. Models are proposed in which PhoP may control SlyA activity via a soluble ligand or SlyA may function as an anti-repressor to allow PhoP activation. The absence of almost all SlyA-activated genes from the Escherichia coli K12 genome suggests that the functional linkage between the SlyA and PhoP/PhoQ regulatory systems arose as Salmonella evolved its distinctive pathogenic lifestyle.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04553.x
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  • 36
    Digitale Medien
    Digitale Medien
    Granulocytes govern the transcriptional response, morphology and proliferation of Candida albicans in human blood (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Survival in blood and escape from blood vessels into tissues are essential steps for the yeast Candida albicans to cause systemic infections. To elucidate the influence of blood components on fungal growth, morphology and transcript profile during bloodstream infections, we exposed C. albicans to blood, blood fractions enriched in erythrocytes, polymorphonuclear or mononuclear leukocytes, blood depleted of neutrophils and plasma. C. albicans cells exposed to erythrocytes, mononuclear cells, plasma or blood lacking neutrophils were physiologically active and rapidly switched to filamentous growth. In contrast, the presence of neutrophils arrested C. albicans growth, enhanced the fungal response to overcome nitrogen and carbohydrate starvation, and induced the expression of a large number of genes involved in the oxidative stress response. In particular, SOD5, encoding a glycosylphosphatidylinositol (GPI)-anchored superoxide dismutase localized on the cell surface of C. albicans, was strongly expressed in yeast cells that were associated with neutrophils. Mutants lacking key genes involved in oxidative stress, morphology or virulence had significantly reduced survival rates in blood and the neutrophil fraction, but remained viable for at least 1 h of incubation when exposed to erythrocytes, mononuclear cells, plasma or blood lacking neutrophils. These data suggest that C. albicans genes expressed in blood were predominantly induced in response to neutrophils, and that neutrophils play a key role during C. albicans bloodstream infections. However, C. albicans is equipped with several genes and transcriptional programmes, which may help the fungus to counteract the attack of neutrophils, to escape from the bloodstream and to cause systemic infections.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04557.x
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  • 37
    Digitale Medien
    Digitale Medien
    The mutation G145S in PrfA, a key virulence regulator of Listeria monocytogenes, increases DNA-binding affinity by stabilizing the HTH motif (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Listeria monocytogenes, a Gram-positive, facultative intracellular human pathogen, causes systemic infections with high mortality rate. The majority of the known pathogenicity factors of L. monocytogenes is regulated by a single transcription factor, PrfA. Hyperhaemolytic laboratory strains of L. monocytogenes express the constitutively active mutant PrfAG145S inducing virulence gene overexpression independent of environmental conditions. PrfA belongs to the Crp/Fnr family of transcription factors generally activated by a small effector, such as cAMP or O2. We present the crystal structures of wild-type PrfA, the first Gram-positive member of the Crp/Fnr family, and of the constitutively active mutant PrfAG145S. Cap (Crp) has previously been described exclusively in the cAMP-induced (DNA-free and -bound) conformation. By contrast, the PrfA structures present views both of the non-induced state and of the mutationally activated form. The low DNA-binding affinity of wild-type PrfA is supported both structurally (partly disordered helix–turn–helix motif, overall geometry of the HTH α-helices deviates from Cap) and by surface plasmon resonance analyses (KD = 0.9 µM). In PrfAG145S the HTH motifs dramatically rearrange to adopt a conformation comparable to cAMP-induced Cap and hence favourable for DNA binding, supported by a DNA-binding affinity of 50 nM. Finally, the hypothesis that wild-type PrfA, like other Crp/Fnr family members, may require an as yet unidentified cofactor for activation is supported by the presence of a distinct tunnel in PrfA, located at the interface of the β-barrel and the DNA-binding domain.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04561.x
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  • 38
    Digitale Medien
    Digitale Medien
    Coccidioidomycosis and blastomycosis: Advances in molecular diagnosis (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Clinical isolates of Coccidioides spp. and Blastomyces dermatitidis can be identified by chemiluminescent DNA probes and PCR assays targeting multicopy genes. In fixed tissue samples, cells of the two fungi are specified by in situ hybridization and PCR assays targeting 18S rDNA but sequencing of the products is mandatory. Nested PCR assays targeting genes encoding species- or genus-specific proteins like proline rich antigen of Coccidioides spp. and B. dermatitidis adhesin facilitate amplification of specific DNA from fixed tissue samples. The value of DNA amplification from native specimens of suspected cases of coccidioidomycosis or blastomycosis still needs to be determined.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.05.011
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  • 39
    Digitale Medien
    Digitale Medien
    Electrophoresis karyotype and chromosome-length polymorphism of Histoplasma capsulatum clinical isolates from Latin America (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Intact chromosomes of 19 clinical isolates of Histoplasma capsulatum recently obtained in Argentina, Mexico and Guatemala and the laboratory reference strain G186B from Panama were analyzed using pulsed-field gel electrophoresis. Chromosomal banding patterns of the human isolates revealed 5–7 bands, ranging from 1.3 to 10 Mbp in size. Strain G186B showed five bands of approximately 1.1, 2.8, 3.3, 5.4 and 9.7 Mbp. Thirteen different electrokaryotypes were identified, indicating that the genome of H. capsulatum varies widely in nature, as observed previously in laboratory strains. No definite association was found between electrokaryotype and geographical or clinical source.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.05.015
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  • 40
    Digitale Medien
    Digitale Medien
    Periodontal pathogens: A quantitative comparison of anaerobic culture and real-time PCR (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Periodontitis is a multi-factorial chronic inflammatory and destructive disease of the tooth-supporting tissues. Quantitative anaerobic culture techniques have been used for microbial diagnosis of the different forms of the disease. The aim of this study was to compare real-time PCR with quantitative anaerobic culture for detection and quantification of 5 prominent periodontal pathogens. Real-time PCR assays with the 16s rRNA genes of Actinobacillus actinomycetemcomitans, Prevotella intermedia, Tannerella forsythensis, Peptostreptococcus micros and Fusobacterium spp. were developed. The PCR was validated on pure cultures of various bacterial strains. Subsequently, subgingival plaque samples from 259 adult patients with periodontitis were analyzed with quantitative anaerobic culture and real-time PCR. A standard curve for DNA quantification was created for each primer-probe set based on colony-forming units equivalents.All bacterial species were correctly identified. The lower limits of detection by PCR varied between 1–50 colony-forming units equivalents depending on the species. No cross-reactivities with heterologous DNA of other bacterial species were observed. Real-time PCR results showed a high degree of agreement with anaerobic culture results. Real-time PCR is a reliable alternative for diagnostic quantitative anaerobic culture of subgingival plaque samples.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.03.011
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  • 41
    Digitale Medien
    Digitale Medien
    Identification of antimicrobial compounds active against intracellular Staphylococcus aureus (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Small-colony variants (SCVs) of Staphylococcus aureus exhibit characteristics of bacteria that can penetrate mammalian cells and remain intracellular and innocuous for indefinite periods. These properties make SCVs a convenient tool that can be used to identify new antibacterial agents having activity against intracellular, quiescent bacteria. Agents active against SCVs could be useful in the treatment of chronic staphylococcal infections such as bovine mastitis. An hemB deletion mutant of S. aureus Newbould, a bovine mastitis isolate, having a stable, genetically defined SCV phenotype, was used in a screening program to identify compounds active against intracellular, gram-positive bacteria. Out of more than 260,000 compounds screened, nine compounds having the desired properties were identified. The range of MICs against gram-positive bacteria was ≤0.12–32 μg ml−1. One of the compounds (no. 8) showed excellent activity against gram-positive (MICs ≤0.12 μg ml−1) and gram-negative (MICs ≤0.12–4 μg ml−1) bacteria. Each of the nine compounds demonstrated efficacy in a neutropenic mouse thigh infection model. Two compounds, including compound no. 8, reduced numbers of bacteria in a mouse mastitis model of infection. Application of a stepwise screening process has identified lead compounds that may be useful for treating persistent, intracellular infections.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.04.003
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  • 42
    Digitale Medien
    Digitale Medien
    Identification and characterization of a novel fibronectin-binding protein gene from Streptococcus equi subspecies zooepidemicus strain VTU211 (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: This work describes the cloning and sequencing of genes encoding fibronectin-binding proteins from Streptococcus equi subspecies zooepidemicus strain VTU211. A gene encoding a cell-wall protein FNZ was amplified and sequenced. In the same bacterial strain, a second gene termed fnz2 was now discovered, encoding another fibronectin-binding protein (FNZ2). The complete amino acid sequence encoded by fnz2 was deduced and compared to that deduced from fnz. The sequence comparison of the fnz and fnz2 predicted that fibronectin-binding activity is localizing a domain in the C terminal part of FNZ2, since this domain is composed of three repeats, which contain a motif similar to what has earlier been found in other fibronectin-binding proteins in streptococci. Three parts of fnz2 [fnz2(1-8), fnz2(2-4), and fnz2(4-3)] were amplified using polymerase chain reaction and ligated into an expression vector, and recombinant FNZ2 proteins were produced in Escherichia coli. Fibronectin bound to the FNZ2(1–8) [amino acids 212–396] and FNZ2(2–4) (amino acids 36–448) but not to the FNZ2(4–3) (amino acids 36–191) in a Western ligand blot, showing that repeat domain of FNZ2 protein was sufficient for binding of fibronectin. Purified FNZ2(2-4) protein was also shown to display collagen-binding activity to collagen-coated microtiter wells. These results show that recombinant FNZ2 has fibronectin- and collagen-binding activities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.04.006
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  • 43
    Digitale Medien
    Digitale Medien
    Cloning of mce1 locus of Mycobacterium leprae in Mycobacterium smegmatis mc2 155 SMR5 and evaluation of expression of mce1 genes in M. smegmatis and M. leprae (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Plasmid pSET152 is a broad host range mobilizable vector which integrates into streptomyces chromosome utilizing att site and int function of ØC31. Transformation of this plasmid into Mycobacterium smegmatis mc2 155 SMR5 gave stable transformants carrying the pSET152 as an integrated copy. Integration occurred at the cross over sequence 5′TTG disrupting the gatA gene (Glu-tRNAGln amidotransferase subunitA), which is non-essential under conditions used. Recombinant pSET152 plasmids carrying mce1 locus of Mycobacterium leprae were used to construct M. smegmatis transformants carrying the mce1 locus in their chromosome. RT-PCR analysis revealed specific transcripts of M. leprae mce in M. smegmatis. The transcribed mRNA carried intergenic regions between genes of mce1 locus indicating that mce1 locus is an operon. Examination of M. leprae specific mRNA from lepromatous leprosy patient's biopsy showed that mce locus is transcribed as an operon in the pathogen also.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.05.004
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  • 44
    Digitale Medien
    Digitale Medien
    Campylobacter jejuni isolated from retail poultry meat, bovine feces and bile, and human diarrheal samples in Japan: Comparison of serotypes and genotypes (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: To determine the significance of poultry and bovine as infectious sources of Campylobacter jejuni in Japan, the serotype distribution and pulsed-field gel electrophoresis (PFGE) patterns of poultry and bovine isolates were compared with those of isolates from patients with diarrhea in Akita (Japan). Serotypes O:2 and O:4-complex were common in human, poultry, and bovine isolates, and serotype O:23,36,53 was common in human and bovine isolates. SmaI PFGE patterns of isolates belonging to these serotypes were generated. Eight PFGE patterns were shared by poultry and human isolates and three patterns were shared by human and bovine isolates. Further analysis of the isolates having the same SmaI PFGE pattern by KpnI PFGE confirmed that four patterns and two patterns were still shared by poultry and human isolates, and bovine and human isolates, respectively. Thus, serotypic and genotypic data indicated a possible link between sporadic human campylobacteriosis and C. jejuni from retail poultry and bovine bile and feces, suggesting that bovine serves as an infectious source of C. jejuni in Japan, as is observed in other countries.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.05.006
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  • 45
    Digitale Medien
    Digitale Medien
    Efficacy of non-toxic deletion mutants of protective antigen from Bacillus anthracis (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Current human anthrax vaccines available in the United States and Europe consist of alum-precipitated supernatant material from cultures of a toxigenic, nonencapsulated strain of Bacillus anthracis. The major component of human anthrax vaccine that confers protection is protective antigen (PA). A second-generation human vaccine using the recombinant PA (rPA) is being developed. In this study, to prevent the toxicity and the degradation of the native rPA by proteases, we constructed two PA variants, delPA (163–168) and delPA (313–314), that lack trypsin (S163–R164–K165–K166–R167–S168) or chymotrypsin cleavage sequence (F313–F314), respectively. These proteins were expressed in Bacillus brevis 47-5Q. The delPAs were fractionated from the culture supernatant of B. brevis by ammonium sulfate at 70% saturation, followed by anion exchange chromatography on a Hitrap Q, Hiload 16/60 superdex 200 gel filtration column and phenyl sepharose hydrophobic interaction column. In accordance with previous reports, both delPA proteins combined with lethal factor protein did not show any cytotoxicity on J774A.1 cells. The delPA (163–168) and delPA (313–314) formulated either in Rehydragel HPA or MPL-TDM-CWS (Ribi-Trimix), elicited a comparable amount of anti-PA and neutralizing antibodies to those of native rPA in guinea pigs, and confers full protection of guinea pigs from 50 ×LD50 of fully virulent B. anthracis spore challenges. Ribi-Trimix was significantly more effective in inducing anti-PA and neutralizing antibodies than Rehydragel HPA. These results indicate the possibility of delPA (163–168) and delPA (313–314) proteins being developed into nontoxic, effective and stable recombinant vaccine candidates.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.05.009
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  • 46
    Digitale Medien
    Digitale Medien
    Temperate bacteriophages DK4 and BcepMu from Burkholderia cenocepacia J2315 are identical (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.06.001
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  • 47
    Digitale Medien
    Digitale Medien
    Combined detection of Chlamydia trachomatis-specific antibodies against the 10 and 60-kDa heat shock proteins as a diagnostic tool for tubal factor infertility: Results from a case-control study in Cameroon (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: A case-control study was conducted to determine the diagnostic value of Chlamydia trachomatis-associated anti-Chsp10 and/or anti-Chsp60 antibodies in the detection of secondary infertility. There were significant associations between C. trachomatis infection and infertility (p 〈 0.01), and between C. trachomatis-specific anti-Chsp10 or anti-Chsp60 antibodies and secondary infertility (p 〈 0.001). A significant correlation was found between anti-Chsp10 and anti-Chsp60 titers (p 〈 0.01). The detection of either C. trachomatis-associated anti-Chsp10 or anti-Chsp60 antibodies cumulatively allowed specific diagnosis of secondary infertility (57.4% sensitivity, 75.5% specificity).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.01.009
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  • 48
    Digitale Medien
    Digitale Medien
    Immunization with glutathione S-transferase and mutant toxic shock syndrome toxin 1 fusion protein protects against Staphylococcus aureus infection (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: To investigate whether immunization with glutathione S-transferase (GST) and mutant toxic shock syndrome toxin 1 (mTSST-1) fusion protein can protect against Staphylococcus aureus infection, we purified a non-toxic mutant GST–mTSST-1 fusion protein. Mice were immunized with the GST–mTSST-1 plus alum adjuvant and then challenged with viable S. aureus. The results showed that the survival rate of GST–mTSST-1-immunized group was higher and the bacteria counts in the organs were significantly lower than those of the non-immunized mice. Immunization with GST–mTSST-1 induced strongly the production of TSST-1 specific antibodies, especially immunoglobulin G1 and immunoglobulin G2b. Furthermore, the serum samples from GST–mTSST-1-immunized mice also significantly inhibited interferon-γ and tumor necrosis factor-α production from murine spleen cells by TSST-1. These results suggest that vaccination with GST–mTSST-1 provides protection against S. aureus infection and that the protection might be mediated by TSST-1-neutralizing antibody.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.01.010
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  • 49
    Digitale Medien
    Digitale Medien
    The role of genome diversity and immune evasion in persistent infection with Helicobacter pylori (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Helicobacter pylori is an important human pathogen that chronically colonizes the stomach of half the world's population. Infection typically occurs in childhood and persists for decades, if not for the lifetime of the host. How is bacterial persistence possible despite a vigorous innate and adaptive immune response? Here we describe the complex role of bacterial diversity and specific mechanisms to avoid or subvert host immunity in bacterial persistence. We suggest that H. pylori finely modulates the extent to which it interacts with the host in order to promote chronic infection, and that it uses diverse mechanisms to do so.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.04.002
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  • 50
    Digitale Medien
    Digitale Medien
    Oral probiotic bacterial administration suppressed allergic responses in an ovalbumin-induced allergy mouse model (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: This study investigated whether orally administered probiotic bacteria (Bifidobacterium bifidum and Lactobacillus casei) and a gram-negative bacterium (Escherichia coli) function as allergic immune modulators to prevent food allergy, according to the hygiene hypothesis. C3H/HeJ mice were sensitized with ovalbumin (OVA) and cholera toxin for 5 weeks. After sensitization, the OVA-induced mice that were not treated with bacteria had significantly increased levels of OVA-specific IgE, total IgE, and IgG1 in sera, as well as scab-covered tails. In comparison, groups treated with B. bifidum BGN4 (BGN4), L. casei 911 (L. casei), or Escherichia coli MC4100 (E. coli) had decreased levels of OVA-specific IgE, total IgE, and IgG1, and decreased levels of mast cell degranulation and tail scabs. OVA-specific IgA levels were decreased in BGN4- and L. casei-treated groups. In conclusion, administration of E. coli, BGN4, or L. casei decreased the OVA-induced allergy response. However, a normal increase in body weight was inhibited in the E. coli-treated mice and in the montreated mice groups during allergy sensitization. Thus, BGN4 and L. casei appear to be useful probiotic bacteria for the prevention of allergy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.05.005
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  • 51
    Digitale Medien
    Digitale Medien
    Expression and secretion of the protective antigen of Bacillus anthracis in Bacillus brevis (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: We used the Bacillus brevis-pNU212 system to develop a mass production system for the protective antigen (PA) of Bacillus anthracis. A moderately efficient expression-secretion system for PA was constructed by fusing the PA gene from B. anthracis with the B. brevis cell-wall protein signal-peptide encoding region of pNU212, and by introducing the recombinant plasmid, pNU212-mPA, into B. brevis 47-5Q. The clone producing PA secreted about 300 μg of recombinant PA (rPA) per ml of 5PY-erythromycin medium after 4 days incubation at 30 °C. The rPA was fractionated from the culture supernatant of B. brevis 47-5Q carrying pNU212-mPA using ammonium sulfate at 70% saturation followed by anion exchange chromatography on a Hitrap Q, a Hiload 16/60 Superdex 200 gel filtration column and a phenyl sepharose hydrophobic interaction column, yielding 70 mg rPA per liter of culture. The N-terminal sequence of the purified rPA was identical to that of native PA from B. anthracis. The purified rPA exhibited cytotoxicity towards J774A.1 cells when combined with lethal factor. The rPA formulated in either Rehydragel HPA or MPL-TDM-CWS adjuvant (Ribi-Trimix) elicited the expression of a large amount of anti-PA and neutralizing antibodies in guinea pigs and completely protected them against a 100 LD50 challenge with fully virulent B. anthracis spores.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.05.008
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  • 52
    Digitale Medien
    Digitale Medien
    Book Review (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.06.002
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  • 53
    Digitale Medien
    Digitale Medien
    Identification of glyceraldehyde-3-phosphate dehydrogenase of epithelial cells as a second molecule that binds to Porphyromonas gingivalis fimbriae (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Binding of Porphyromonas gingivalis to the host cells is an essential step in the pathogenesis of periodontal disease. P. gingivalis binds to and invades epithelial cells, and fimbriae are thought to be involved in this process. In our earlier studies, two major epithelial cell components of 40 and 50 kDa were identified as potential fimbrial receptors. Sequencing of a cyanogen bromide digestion fragment of the 50-kDa component resulted in an internal sequence identical to keratin I molecules, and hence this cytokeratin represents one of the epithelial cell receptors for P. gingivalis fimbriae. In this study, the 40-kDa component of KB cells was isolated and its amino-terminal sequence determined. The N-terminal amino sequence was found to be GKVKVGVNGF and showed perfect homology with human glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Furthermore, purified P. gingivalis fimbriae were found to bind to rabbit muscle GAPDH. Antibodies directed against internal peptide 49–68 and 69–90 of fimbrillin were shown to inhibit the binding of P. gingivalis and of fimbriae to epithelial cells. Antibodies against these peptides also inhibited the binding of fimbriae to GAPDH. Our results confirmed that the amino-terminal domain corresponding to amino residues 49–68 of the fimbrillin protein is the major GAPDH binding domain. These studies point to GAPDH as a major receptor for P. gingivalis major fimbriae and, as such, GAPDH likely plays a role in P. gingivalis adherence and colonization of the oral cavity, as well as triggering host cell processes involved in the pathogenesis of P. gingivalis infections.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.01.006
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  • 54
    Digitale Medien
    Digitale Medien
    Identification and characterization of the TonB region and its role in transferrin-mediated iron acquisition in Haemophilus parasuis (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Haemophilus parasuis is the causative agent of Glässer's disease, which is responsible for considerable economic losses in the pig-rearing industry. The aim of the study reported here was the identification, sequencing and molecular characterization of the TonB region that includes tonB, exbBD, and tbpBA genes in H. parasuis. In addition, two fusion proteins were generated. One of them (pGEX-6P-1-GST-TbpB) contained the first 501 amino acids of H. parasuis TbpB protein, while the second (pBAD-Thio-TbpB-V5-His) included the first 102 amino acids of H. parasuis TbpB N-terminus domain. A panel of 14 hybridomas secreting monoclonal antibodies was raised against the two recombinant TbpB fusion proteins. Furthermore, to assess whether the expression of the H. parasuis ExbB, TbpB, and TbpA proteins was upregulated under conditions of restricted availability of iron, a rabbit polyclonal antibody against H. parasuis TbpB-His fusion protein was produced. A rabbit polyclonal antibody against serotype 7 of Actinobacillus pleuropneumoniae ExbB and TbpA proteins was also used for the detection of the homologous proteins in H. parasuis. Overall, the data indicate that H. parasuis, like other members of the Pasteurellaceae family, possesses the genetic elements of the TonB region for iron acquisition and the transferrin-binding proteins encoded under this region are upregulated under restricted iron availability.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.02.008
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  • 55
    Digitale Medien
    Digitale Medien
    Comparative evaluation of intranasal and subcutaneous route of immunization for development of mucosal vaccine against experimental tuberculosis (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Activation of mucosal immunity in the respiratory tract is crucial for protection against respiratory infections. Whether the intranasal route of vaccination imparts better protection against pulmonary tuberculosis than that of subcutaneous vaccination remains a debatable issue. In this study, we have investigated the effect of the routes of immunization on the induction of immunoprotection against experimental tuberculosis employing mycobacterial culture filtrate proteins complexed with dimethyldioctadecylammonium bromide. Vaccination via intranasal and subcutaneous routes triggered immune activation in the spleen and cervical lymph node, while the former route of vaccination lead to higher antigen-specific lymphocyte proliferation, interferon-γ, interleukin-12 and interleukin-4 responses in cervical lymph node and induction of antigen-specific IgA responses at mucosal level of the respiratory tract. Mice vaccinated via the intranasal route were found to be better protected against experimental tuberculosis particularly in lung compared to subcutaneous-immunized mice. These results emphasize the importance of the intranasal route vaccination in tuberculosis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.02.009
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  • 56
    Digitale Medien
    Digitale Medien
    A swine toll-like receptor 2-expressing transfectant as a potential primary screening system for immunobiotic microorganisms (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 44 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Toll-like receptor 2 (TLR2) has been shown to mediate cell signaling in response to microbial cell wall components, such as peptidoglycan, lipoteichoic acid, microbial lipoprotein, and zymosan. In this study, we cloned the swine TLR2 and used it to transfect Chinese hamster ovary K-1 cells. We demonstrated that the swine TLR2-expressing transfectant can bind not only zymosan from yeast cell wall components but also intact lactic acid bacteria, resulting in the activation of nuclear factor-κB. These findings suggest that the swine TLR2-expressing transfectant can be very useful for the primary screening of immunobiotic microorganisms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.12.009
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  • 57
    Digitale Medien
    Digitale Medien
    Distribution of “classic” virulence factors among Salmonella spp. (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 44 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Whether an infection with Salmonella spp. leads to a disease largely depends on the virulence of the strain and the constitution of the host. The virulence of the strain is determined by so-called virulence factors. Whereas a number of virulence factors of Salmonella have been identified only recently, others have been studied for decades. These latter virulence factors i.e., virulence-plasmids, toxins, fimbriae and flagella are therefore referred to as “classic” virulence factors. Here we present an overview on the distribution of (genes coding for) these virulence factors among Salmonella spp. The pathogenicity islands of Salmonella are also reviewed, all be it briefly, since they contain a major part of the virulence genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.02.002
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  • 58
    Digitale Medien
    Digitale Medien
    Correlation of the Helicobacter pylori adherence factor BabA with duodenal ulcer disease in four European countries (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 44 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Helicobacter pylori strains harboring the vacAs1, cagA and babA2 have been associated with ulcer disease (UD). We compared the prevalence of these different genotypes and adhesive properties in H. pylori infected patients with UD in four European countries. Genomic DNA was isolated from 314 H. pylori strains: Germany (GER; n= 92), Sweden (SWE, n= 74), Portugal (POR, n= 91) and Finland (FIN, n= 57). The frequencies of babA2 genotype varied from 35% to 60%. Triple-positive strains (vacAs1+, cagA+ and babA2+) were significantly associated with UD in GER and POR and were closely correlated with UD in FIN, but not in SWE. Classification as triple-positive strains had a higher specificity for detection of UD in GER, POR and FIN than type1 or cagA+ strains. In vitro adhesion assays revealed that Swedish strains showed high adhesion properties and were thus correlated with the diagnosis of UD, although PCR detected the babA2 gene at lower frequencies and failed to show a correlation with UD. This finding appears to reflect allelic variations of the babA2 gene in SWE, although adhesive properties of the strains are retained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.10.010
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  • 59
    Digitale Medien
    Digitale Medien
    Identification of a new sialic acid-binding protein in Helicobacter pylori (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 44 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: A novel sialic acid-specific lectin has been isolated from Helicobacter pylori lysate using fetuin–agarose affinity chromatography followed by cleavage of the α(2,3) and α(2,6) linkages of sialic acids using neuraminidase. The protein had a molecular weight of 17.5 kDa on sodium dodecyl sulfate (SDS)–polyacrylamide gel electrophoresis (PAGE) and was identified by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry to be protein of unknown function with gene number HP0721. Recombinant HP0721 was shown to bind to fetuin–agarose and sialic acid-containing glycosphingolipids on thin-layer plates suggesting this protein may represent another sialic acid-specific adhesin of H. pylori. A H. pylori mutant defective for HP0721 was generated and its ability to bind to human AGS cells assayed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.11.008
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  • 60
    Digitale Medien
    Digitale Medien
    Helicobacter pylori antibodies and gastric cancer: a gender-related difference (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 44 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Helicobacter pylori has been proposed as a causative agent of gastric cancer. The aim of this study was to define serum antibodies response against different H. pylori antigens in patients with gastric cancer. Serum samples were collected from 115 Lithuanian patients with non-cardia gastric cancer and 110 age- and sex-matched controls without cancer. Heat-stable, low-molecular-mass, and outer membrane proteins were used as antigens to analyze serum IgG antibody response against H. pylori by enzyme-linked immunosorbent assay. Seroprevalence of H. pylori using low-molecular-mass antigen was significantly higher in gastric cancer patients, compared to controls (77% versus 57%, p 〈 0.05). Significant differences in the prevalence of H. pylori infection between gastric cancer patients and controls were found in females using all three studied antigens: heat-stable (98% versus 84%, p 〈 0.05), low-molecular-mass (88% versus 48%, p 〈 0.05) and outer membrane proteins (78% versus 57%, p 〈 0.05). In males, no significant differences were revealed between gastric cancer patients and controls. There may be other cofactors in addition to H. pylori that are important for the development of gastric cancer. H. pylori seems, however, to be a more important for development of gastric cancer in females than in males or males may have more confounding risk factors for gastric cancer than females.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.11.011
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  • 61
    Digitale Medien
    Digitale Medien
    Characterization of the PCR inhibitory effect of bile to optimize real-time PCR detection of Helicobacter species (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 44 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The inhibitory effect of human and porcine bile samples to detect Helicobacter DNA was studied by adding different concentrations of bile samples to PCR mixtures of six thermostable DNA polymerases containing cagA specific primers and Helicobacter pylori DNA. PCR products were amplified by using the Rotorgene system and SYBR Green I. Among the six DNA polymerases tested, rTth had the lowest sensitivity to bile inhibitors, whereas Taq and Tfl had the highest sensitivity. Bile proteins did not inhibit AmpliTaq DNA polymerase, whereas the fraction containing mainly bile acids and their salts inhibited the amplification capacity of AmpliTaq. Heating human bile at 98 °C and adding casein and formamide to the reaction mixture reduced the PCR inhibitory effect of bile. Therefore, a pre-PCR treatment based on dilution and heating of bile, adding casein and formamide to the reaction mixture of rTth DNA polymerase was found efficient to amplify DNA directly in bile.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.12.004
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  • 62
    Digitale Medien
    Digitale Medien
    CpG oligonucleotides partially inhibit growth of Mycobacterium tuberculosis, but not Salmonella or Listeria, in human monocyte-derived macrophages (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Immunostimulatory DNA sequences and their synthetic oligonucleotide analogs (CpG-ODN) activate innate immunity and can stimulate antibacterial effects against numerous intracellular pathogens. While it has been shown previously that CpG-ODN inhibit growth of Mycobacterium avium in murine and human macrophages, we now report that Mycobacterium tuberculosis growth can be inhibited by CpG-ODN treatment of human monocyte-derived macrophages (hMDM). This inhibitory effect was reversed by IFN-γ, which has been shown repeatedly to enhance the growth of virulent M. tuberculosis in cultured hMDM. The antibacterial effect of CpG-ODN in human macrophages was specific for M. tuberculosis when compared to other intracellular pathogens including Listeria monocytogenes and Salmonella enterica serovar Dublin. These data indicate that CpG-ODN can improve the ability of hMDM to contain growth of virulent M. tuberculosis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.05.007
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  • 63
    Digitale Medien
    Digitale Medien
    Involvement of the virulence gene products of Yersinia enterocolitica in the immune response of infected mice (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The virulence of Yersinia enterocolitica is known to be highly dependent on its virulence plasmid. However, it remains unclear whether the virulence plasmid is engaged also in the induction of cell-mediated immunity that is essential for protective immunity in the host. In this study, we have compared the induction of type 1 helper T cell immunity against Y. enterocolitica using a virulent strain (P+) harboring the pYV plasmid and an avirulent strain (P−) harboring no pYV. Spleen cells from both groups of mice immunized with 1/10 LD50 of P+ strain and those with 1/10 LD50 of P− strain produced a high level of gamma interferon (IFN-γ) upon stimulation with heat-killed bacteria, and CD4+ T cells were exclusively responsible for IFN-γ production. When crude Yersinia outer proteins (Yops) were used for antigenic stimulation, IFN-γ response of immune spleen cells against crude Yops was observed only in mice immunized with P+ strain. Flowcytometric analysis revealed a significant level of increase in IFN-γ-producing CD8+ T cells as well as the increase in IFN-γ-producing CD4+ T cells against crude Yops. These results suggest that the virulence plasmid of Y. enterocolitica is involved in the induction of Th1-type of possibly protective T cells in infected mice.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.05.010
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  • 64
    Digitale Medien
    Digitale Medien
    Antibodies against human muscle enolase recognize a 45-kDa bacterial cell wall outer membrane enolase-like protein (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Enolase, is a glycolytic enzyme ubiquitous in higher organisms, where it forms tissue specific dimers of isoforms, also found in the cytoplasm of fermentative bacteria. The aim of this work was to identify enolase-like proteins in the cell wall of some Gram-negative bacteria using antibodies against human β-enolase, an isoenzyme specific to skeletal and heart muscles. Cell wall outer membrane protein (OMP) preparations were obtained from 9 strains of Enterobacteriaceae and one of Pseudomonas aeruginosa. Specific enzymatic enolase activity was detected in the supernatant fractions of cytosolic and inner membrane material, but not in purified OMP preparations. Rabbit polyclonal antibodies specific against human β-enolase were prepared and purified using immobilized human β-enolase in affinity chromatography. In SDS–polyacrylamide gel electrophoresis and immunoblotting assay of purified OMP preparations, rabbit anti-enolase antibody interacted specifically with a few OMPs, of which a 45-kDa band also interacted with human sera of patients presenting Buerger disease and atherosclerosis. The most distinct interaction of human sera was observed with a 45-kDa OMP of Klebsiella pneumoniae. This protein was further isolated from K. pneumoniae cell mass in two ways, namely preparative SDS–polyacrylamide gel electrophoresis and specific affinity chromatography using immobilized affinity-purified rabbit antibody raised against human β-enolase. The data obtained from tandem mass spectrometry tryptic peptide analysis and sequence comparison of human and bacterial enolases using protein databases, could reveal the similarity in the epitopes between membrane enolase-like protein from Klebsiella and human β-enolase. The results show that the protein present in all studied strains has a common epitope on human β-enolase. These data raise the question whether such a bacterial protein might be a marker for detecting and monitoring damage to skeletal and heart muscles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.01.005
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  • 65
    Digitale Medien
    Digitale Medien
    Transcriptional regulation of β-defensin-2 by lipopolysaccharide in cultured human cervical carcinoma (HeLa) cells (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Human β-defensin-2 (hBD-2) is an antimicrobial peptide with a broad spectrum of antimicrobial activity against bacteria, yeast and fungi. Here, we analyzed the transcriptional regulation of hBD-2 in cultured human cervical carcinoma (HeLa) cells with or without lipopolysaccharide (LPS). DNA from position −329 to −39 in the hBD-2 promoter region contained the consensus binding sites for transcription factors, one site for nuclear factor for IL-6 expression (NF-IL6) and two sites for nuclear factor-κB (NF-κB). Reporter gene assays for promoter activity revealed that the region had the highest level of responsiveness to LPS. Furthermore, mutations in both of the NF-κB binding sites caused a significant reduction of the responsiveness to LPS, whereas mutation in the NF-IL6 binding site resulted in an elevation of the basal promoter activity. Electrophoretic mobility shift assays demonstrated that LPS induced the binding of HeLa nuclear factors to 60-bp probe containing the two NF-κB binding sites, suggesting that the sites were essential for the binding. Our results suggest that the two NF-κB binding sites contribute to LPS-mediated hBD-2 transcription while the NF-IL6 binding site represses LPS-independent hBD-2 transcription in the HeLa cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.01.008
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  • 66
    Digitale Medien
    Digitale Medien
    In vivo expression of the 25-kDa laminin-binding protein of Helicobacter pylori (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The gastroduodenal pathogen Helicobacter pylori has been shown to inhibit the interaction between the extracellular matrix protein laminin and its receptor on gastric epithelial cells, potentially contributing to a loss of mucosal integrity. As a 25-kDa outer membrane protein of H. pylori in association with the bacterial lipopolysaccharides (LPS) mediates attachment to laminin, the aim of this study was to determine whether the 25-kDa protein is produced by H. pylori in infected hosts. We examined the immune response to the 25-kDa laminin binding protein in 12 paediatric patients; samples from a H. pylori-negative healthy adult were used as controls. In immunoblotting, antibodies to a 25-kDa protein were found in the serum and saliva of H. pylori-positive individuals only, and using the positive sera and saliva, laminin binding to the 25-kDa protein was inhibited. Thus, the 25-kDa laminin-binding protein is produced by H. pylori in infected hosts.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.09.006
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  • 67
    Digitale Medien
    Digitale Medien
    In vitro inhibition of Helicobacter pylori by micromycetes (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The anti-Helicobacter pylori effect of 22 micromycetes were studied against one standard strain and 11 clinical isolates of H. pylori. Penicillium ochlochloron and Penicillium funiculosum have been proven the most active fungi against this microorganism. Further bio-guided chemical analysis of P. funiculosum afforded an active component identified as (+) 2,3,4-trihydroxybutanamide.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.02.004
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  • 68
    Digitale Medien
    Digitale Medien
    Molecular heterogeneity in Yersinia enterocolitica and ‘Y. enterocolitica-like’ species – Implications for epidemiology, typing and taxonomy (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Yersinia enterocolitica is an extremely heterogeneous species. Serotyping and biotyping have been used extensively, in the past, to study its heterogeneity and epidemiology. Application of methods like ribotyping, pulsed-field gel electrophoresis and a host of other genomic techniques have further revealed molecular heterogeneity in this species. Furthermore, these methods may be used effectively to supplement serotyping and biotyping schema for studying epidemiology of Y. enterocolitica. This is evident from the ability of some of these methods to subtype strains belonging to serogroups O:3, O:9 and O:8 – which are most commonly encountered in human Yersiniosis. Multilocus enzyme electrophoresis and nucleotide sequencing have reiterated the taxonomic relationships of this organism. However there is paucity of information about the molecular heterogeneity of ‘Y. enterocolitica-like’ species, which need to be addressed in the future. Also, newer techniques such as amplified fragment length polymorphism, VNTR-based typing and multilocus sequence typing should be applied to further understand epidemiology, population structure and evolutionary genetics of Y. enterocolitica and ‘Y. enterocolitica-like’ species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.03.006
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  • 69
    Digitale Medien
    Digitale Medien
    Photoinactivation of Escherichia coli using porphyrin derivatives with different number of cationic charges (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 44 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The photodynamic effect of meso-substituted cationic porphyrins, 5-[4-(trimethylammonium)phenyl]-10,15,20-tris(2,4,6-trimethoxyphenyl)porphyrin iodide 1, 5,10-di(4-methylphenyl)-15,20-di(4-trimethylammoniumphenyl)porphyrin iodide 2 and 5-(4-trifluorophenyl)-10,15,20-tris(4-trimethylammoniumphenyl)porphyrin iodide 3, have been investigated in both homogeneous medium bearing photooxidizable substrates and in vitro on a typical gram-negative bacterium Escherichia coli. Absorption and fluorescence spectroscopic studies were compared in N,N-dimethylformamide. Fluorescence quantum yields (φF) of 0.10, 0.06 and 0.08 were calculated for porphyrins 1, 2 and 3, respectively. The singlet molecular oxygen, O2(1Δg), production was evaluated using 9,10-dimethylanthracene yielding values of 0.66, 0.36 and 0.42 for porphyrins 1, 2 and 3, respectively. Guanosine 5′-monophosphate was used as biological substrate model. Similar decomposition of guanosine 5′-monophosphate was obtained using these cationic porphyrins as sensitizer. In biological medium, photosensitized inactivation of E. coli was analyzed using cells without and with one washing step. E. coli cultures were treated with sensitizer at 37 °C for 30 min in dark. In both procedures, a higher photoinactivation of cells (〉99.999%) was found for cells treated with 10 μM of tricationic porphyrin 3 and irradiated for 5 min with visible light. Porphyrins 1 and 2 only show an important photodamage when the cells are irradiated without washing step. These results indicated that the tetracationic porphyrin 3 could be a promising sensitizer with potential applications in the photoinactivation of bacterial cells by photodynamic therapy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.12.007
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  • 70
    Digitale Medien
    Digitale Medien
    Biological importance of the two Toll-like receptors, TLR2 and TLR4, in macrophage response to infection with Candida albicans (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 44 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The aim of this study was to assess the role of TLR2, TLR4 and MyD88 accessory molecule in the effector and secretory response of macrophages to viable microbial agents. Using TLR-deleted macrophage cell lines generated from the bone marrow of genetically engineered mice (TLR4 gene-deficient, MyD88- and TLR2-knockout mice) and wild-type control mice, we found that TLR2-deleted macrophages exhibit increased ability to contain Candida albicans infection compared to TLR2+/+ counterpart. In contrast, both MyD88+/+ and TLR4+/+ macrophages retain levels of functional activity comparable to that of the respective wild-type MyD88+/+ and TLR4+/+ controls. The difference in anticandidal effector functions observed between TLR2+/+ and TLR2+/+ macrophages is abrogated upon opsonization of the fungal target and interestingly is not observed when using other microbial targets, such as Streptococcus pneumoniae and Helicobacter pylori. When tested for secretory response to C. albicans, TLR2-deleted macrophages show a pattern of cytokine production similar to that of TLR2+/+ controls. Finally, flow cytometry analysis reveals that TLR2-deleted macrophages express only TLR4, while, as expected, TLR2+/+ macrophages are both TLR2 and TLR4 positive; in no cases, modulation of such markers occurs in macrophages exposed to C. albicans infection. In conclusion, these data indicate that TLR2 and TLR4 have different biological relevance, in which TLR2 but not TLR4, is involved in the accomplishment of macrophage-mediated anticandidal activity, while the secretory response to C. albicans appears to be TLR4 but not TLR2-dependent.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.12.005
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  • 71
    Digitale Medien
    Digitale Medien
    A study on the bacterial photo-toxicity of phenothiazinium based photosensitisers (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: “Comet assay” showed light activated (3.15 J cm−2 over 30 min) phenothiazinium based photosensitisers (PhBPs) to induce photo-damage of Staphylococcus aureus DNA, as indicated by DNA “tails” between 80 and 120 μm. In general, PhBPs exhibited significant singlet oxygen yields (ΦΔPhBP 〉 0.7), suggesting the use of type II mechanisms of photo-oxidation. However, the photodynamic action of PhBPs on DNA showed generally insignificant production of 7,8-dihydro-8-oxo-2′-deoxyguanosine, normally a major product of type II DNA photo-oxidation. These combined results show DNA to be a major site of action of PhBPs and suggest that this action may involve type II attack on a nucleoside(s) other than guanosine.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.09.002
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  • 72
    Digitale Medien
    Digitale Medien
    Structure of the O-polysaccharide and serological studies of the lipopolysaccharide of Proteus penneri 60 classified into a new Proteus serogroup O70 (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: An alkali-treated lipopolysaccharide of Proteus penneri strain 60 was studied by chemical analyses and 1H, 13C and 31P NMR spectroscopy, and the following structure of the linear pentasaccharide–phosphate repeating unit of the O-polysaccharide was established:〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:09288244:FIM351:FIM_351_mu1"/〉 Rabbit polyclonal O-antiserum against P. penneri 60 reacted with both core and O-polysaccharide moieties of the homologous LPS. Based on the unique O-polysaccharide structure and serological data, we propose to classify P. penneri 60 into a new, separate Proteus serogroup O70. A weak cross-reactivity of P. penneri 60 O-antiserum with the lipopolysaccharide of Proteus vulgaris O8, O15 and O19 was observed and discussed in view of the chemical structures of the O-polysaccharides.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.09.004
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  • 73
    Digitale Medien
    Digitale Medien
    Gamma delta T cell responses associated with the development of tuberculosis in health care workers (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: This study evaluated T cell immune responses to purified protein derivative (PPD) and Mycobacterium tuberculosis (Mtb) in health care workers who remained free of active tuberculosis (HCWs w/o TB), health care workers who went on to develop active TB (HCWs w/TB), non-health care workers who were TB free (Non-HCWs) and tuberculosis patients presenting with minimal (Min TB) or advanced (Adv TB) disease. Peripheral blood mononuclear cells (PBMC) were stimulated with Mtb and PPD and the expression of T cell activation markers CD25+ and HLA-DR+, intracellular IL-4 and IFN-γ production and cytotoxic responses were evaluated. PBMC from HCWs who developed TB showed decreased percentages of cells expressing CD8+CD25+ in comparison to HCWs who remained healthy. HCWs who developed TB showed increased γδ TCR+ cell cytotoxicity and decreased CD3+γδ TCR+ cell cytotoxicity in comparison to HCWs who remained healthy. PBMC from TB patients with advanced disease showed decreased percentages of CD25+CD4+ and CD25+CD8+ T cells that were associated with increased IL-4 production in CD8+ and γδ TCR+ phenotypes, in comparison with TB patients presenting minimal disease. TB patients with advanced disease showed increased γδ TCR+ cytotoxicity and reduced CD3+γδ TCR+ cell cytotoxicity. Our results suggest that HCWs who developed TB show an early compensatory mechanism involving an increase in lytic responses of γδ TCR+ cells which did not prevent TB.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.09.005
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  • 74
    Digitale Medien
    Digitale Medien
    Evaluation of touch-down real-time PCR based on SYBR Green I fluorescent dye for the detection of Neisseria meningitidis in clinical samples (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Antibiotic treatment prior to transport or admission of patients to hospital has reduced the proportion of patients with invasive meningococcal disease (IMD) from whom Neisseria meningitidis can be isolated by standard microbiological techniques. Assays to detect the crgA gene were used to detect meningococcal DNA by both conventional polymerase chain reaction (PCR) and real-time PCR (RTPCR) in relation to microbiological diagnosis of cases over two years between 2002 and 2003. The sensitivity of both PCR assays for culture-confirmed cases was 93% and the specificity was 98.6%. Agreement between the two PCR assays was 96.2%. The inter- and intra-assay variations and effects of different amounts of DNA on the melting temperatures were examined. The touch-down RTPCR based on SYBR Green I fluorescent dye detected and characterized N. meningitidis in clinical samples within one hour.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.10.011
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  • 75
    Digitale Medien
    Digitale Medien
    Intestinal immunity of Escherichia coli NISSLE 1917: a safe carrier for therapeutic molecules (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The development of novel approaches that allow accurate targeting of therapeutics to the intestinal mucosa is a major task in the research on intestinal inflammation. For the first time, a live genetically modified bacterial strain has been approved by Dutch authorities as a therapeutic agent for experimental therapy of intestinal bowel disease (IBD) in humans. Genetically modified probiotics can very well be used as carriers for localized antigen delivery into the intestine. Therapeutic safety, however, of such a carrier organism, is crucial, especially when a specific probiotic strain has to be used under diseased conditions. In this study, we tested the potential of Escherichia coli NISSLE 1917 to serve as a safe carrier for targeted delivery of recombinant proteins to the intestinal mucosa. In a well-defined and very sensitive immunological system, we demonstrate that intestinal recombinant E. coli NISSLE 1917 has no effect on migration, clonal expansion and activation status of specific CD4+ T cells, neither in healthy mice nor in animals with acute colitis. Furthermore, recombinant E. coli NISSLE 1917 has no effect on the induction or breakdown of peripheral T-cell tolerance in an autoimmune environment. The excellent colonization properties of E. coli NISSLE 1917 render this strain an ideal candidate as carrier organism for gut-focused in situ synthesis of therapeutic molecules.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.10.023
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  • 76
    Digitale Medien
    Digitale Medien
    Induction of immune response to Streptococcus pneumoniae by administration of oral viridans streptococci via phosphorylcholine determinant (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Expression of the phosphorylcholine (PC) epitope was examined in 48 viridans streptococcal strains, including Streptococcus pneumoniae R36a as the positive control, and their immunogenicity to induce an S. pneumoniae-cross-reactive response was evaluated in mice. Thirteen strains were found to express the PC epitope, while no obvious association was found between the taxonomic categories and PC expression. Serum antibody responses to S. pneumoniae cells were induced in mice by intraperitoneal injection of the PC-positive, but not PC-negative, strains. The cross-reactive antibodies induced by non-pneumococcal oral streptococci were readily inhibited by free hapten PC. IgM was the sole isotype of the anti-pneumococcal and anti-PC antibodies, and the phenomenon of immunological memory was not observed. Since the anti-PC antibody is critically important for resistance against pneumococcal infection in mice, the present results indicate the possibility that PC-expressing oral commensal bacteria have a significant influence on the hosts’ responsiveness to S. pneumoniae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.11.001
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  • 77
    Digitale Medien
    Digitale Medien
    Induction of antigen-specific immune responses by oral vaccination with Saccharomyces cerevisiae expressing Actinobacillus pleuropneumoniae ApxIIA (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: An effective way of inducing both mucosal and systemic immune responses to protect against Actinobacillus pleuropneumoniae serotype 2 Korean isolate was examined in mice by oral immunization using Saccharomyces cerevisiae expressing the ApxIIA protein. The immunogenicity of the yeast-derived ApxIIA antigen was confirmed by the challenge test and ApxIIA-specific IgG antibody response assay. The group subcutaneously immunized with the protein extracted from the yeast expressing ApxIIA showed a higher survival rate after challenging with A. pleuropneumoniae serotype 2 isolate and IgG antibody level in serum than the group injected with that prepared from the yeast harboring vector only.Feeding the yeast expressing ApxIIA to mice induced both systemic and mucosal immune responses against the antigen. ApxIIA-specific IgA antibody titers and the number of IgA-secreting cells of mice vaccinated with S. cerevisiae expressing ApxIIA dose-dependently increased from the third immunization in both intestine and lung (P 〈 0.01). A similar tendency of ApxIIA-specific IgG antibody responses was observed in the sera. The protective efficacy of the oral immunization was then evaluated by a challenge with a minimal lethal dose (MLD, 4.5 × 107 CFU/ml) of the A. pleuropneumoniae serotype 2 isolate. Fifty percent of the 30 mg administered group and 30% of the 15 mg administered group survived while none of the mice in the control groups survived after 36 h. These results suggest that feeding animals the yeast expressing the antigen can be an effective strategy to induce protective immune responses against A. pleuropneumoniae infection.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.07.004
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  • 78
    Digitale Medien
    Digitale Medien
    Induction of CD69 expression and Th1 cytokines release from human peripheral blood lymphocytes after in vitro stimulation with Alloiococcus otitidis and three middle ear pathogens (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Alloiococcus otitidis is a recently discovered pathogen of otitis media. However, only a limited number of studies are available about the pathogenic and immunological role of A. otitidis. The aim of this study was to investigate the activation and the cytokine production of human peripheral blood lymphocytes at the early immune response after stimulation with A. otitidis. After stimulation of whole human peripheral blood lymphocytes for 18 h with whole killed A. otitidis or the three major middle ear pathogens (Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis), the expression of CD69 and the production of cytokines were analyzed. The expression of CD69 on T cells and B cells was dose-dependently enhanced after stimulation with A. otitidis. The release of interleukin (IL)-12 was induced after stimulation with A. otitidis, whereas the release of IL-4 was not induced after stimulation with A. otitidis. In addition, the release of interferon (IFN)-γ was induced after stimulation with A. otitidis. Although the release of IFN-γ started within 18 h after stimulation with A. otitidis, intracellular production of IFN-γ was not observed in either CD4+ T cells or CD8+ T cells within 18 h upon stimulation. The patterns of CD69 expression and T helper-type 1 (Th1)-promoting cytokines production were similarly shown when human peripheral blood lymphocytes were stimulated with the other three major pathogens. Our results suggest that A. otitidis has sufficient immunogenic potential to modulate a host immune response, like the other three major middle ear pathogens, and also suggest that the immunogenicity of A. otitidis is very similar, at the early immune response, to that of the three major middle ear pathogens.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.10.014
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  • 79
    Digitale Medien
    Digitale Medien
    Invertebrates as animal models for Staphylococcus aureus pathogenesis: a window into host–pathogen interaction (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Recently, the use of invertebrate models of infection has given exciting insights into host–pathogen interaction for a number of bacteria. In particular, this has revealed important factors of the host response with remarkable parallels in higher organisms. Here, we review the advances attained in the elucidation of virulence determinants of a major human pathogen, Staphylococcus aureus, in relation to the invertebrate models thus far applied, the silkworm (Bombyx mori), the fruit fly (Drosophila melanogaster) and the roundworm (Caenorhabditis elegans). Also, the major pathways of host defence are covered in light of the response to S. aureus and the similarities and divergences in innate immunity of vertebrates and invertebrates. Consequently, we comparatively consider pathogen recognition receptors, signal transduction pathways (including Toll, Imd and others), and the humoral and cellular antimicrobial effectors. The technically convenient and ethically acceptable invertebrates appear as a valuable first tool to discriminate molecules participating from both sides of the host–S. aureus interaction as well as a high throughput method for antimicrobial screening.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.11.003
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  • 80
    Digitale Medien
    Digitale Medien
    Molecular and experimental virulence of Listeria monocytogenes strains isolated from cases with invasive listeriosis and febrile gastroenteritis (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: We analyzed 27 Listeria monocytogenes strains of serotypes 1/2b and 4b, from invasive and gastroenteric listeriosis, for molecular and experimental virulence. Molecular virulence was tested by PCR for the presence of 8 major virulence-associated genes and genetic polymorphisms through restriction enzyme analysis; genomic DNA typing using pulsed-field gel electrophoresis was also performed. Experimental virulence was evaluated through intra-peritoneal and intra-gastric mouse virulence assays. Our results showed no significant differences in the virulence-related molecular properties of the strains analyzed. All strains were equally pathogenic following intra-peritoneal inoculation of mice. In mice inoculated intra-gastric with 4 representative strains of the 2 types of listeriosis, there were no significant differences in the bacterial count when comparing invasive and gastroenteric strains, suggesting that the strains were comparable in terms of mean oral infectivity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.11.005
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  • 81
    Digitale Medien
    Digitale Medien
    Memory immune response generated in Cercopithecus aethiops against meningococcal polysaccharide serogroup C conjugate vaccine (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The chemical conjugation of bacterial polysaccharide to carrier proteins has proved to be an efficient tool to improve the immunological response against these bacterial antigens. In this study, we characterized the antibody response generated in a non-human primate model against the meningococcal capsular polysaccharide serogroup C (CCPS) conjugated to the P64k protein. Similar to licensed vaccines the CCPS conjugate is able to generate a good memory immune response with antibody titers threefold higher than the free CCPS. Three different ELISA protocols were used to measure the antibody response and the importance of the coating antigen was demonstrated. The ELISA using the derivatized CCPS showed the best results and had a high correlation with the bactericidal activity. The antibodies elicited showed a high protective capacity when assayed in the infant rat protection model.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.07.003
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  • 82
    Digitale Medien
    Digitale Medien
    Sensitivity of Borrelia genospecies to serum complement from different animals and human: a host–pathogen relationship (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Different Borrelia species and serotypes were tested for their sensitivity to serum complement from various animals and human. Complement-mediated Borrelia killing in cattle, European bison and deer was higher irrespective of the Borrelia species whereas in other animals and human it was intermediate and Borrelia species-dependent. Activation of the alternative complement pathway by particular Borrelia strain was in correlation with its sensitivity or resistance. These results support the incompetent reservoir nature of cattle, European bison, red, roe and fallow deer, at the same time present the probable reservoir nature of mouflon, dog, wolf, cat and lynx. In short, this study reviews Borrelia–host relationship and its relevance in reservoir competence nature of animals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.07.012
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  • 83
    Digitale Medien
    Digitale Medien
    Kinetic studies of bioactive products nitric oxide and 8-iso-PGF2α in Burkholderia pseudomallei infected human macrophages, and their role in the intracellular survival of these organisms (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The oxidative response of Burkholderia pseudomallei and Escherichia coli infected macrophages from normal and melioidosis subjects was determined by measuring the production of nitric oxide which is one of the reactive nitrogen intermediates, and the activation state of these macrophages was determined by measuring the generation of 8-iso-PGF2α, a bioactive product of free radical induced lipid peroxidation. Macrophages obtained from the melioidosis patients generated significantly lower levels of nitric oxide and 8-iso-PGF2α compared to macrophages obtained from the normal subjects (P 〈 0.001). The reduced efficiency of the oxygen dependent microbicidal mechanism in macrophages of melioidosis patients may be one of the survival strategies developed by B. pseudomallei to remain viable intracellularly.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.08.001
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  • 84
    Digitale Medien
    Digitale Medien
    Humoral immune response against soluble and fractionate antigens in experimental sporotrichosis (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Sporotrichosis is a chronic granulomatous mycosis caused by the dimorphic fungus Sporothrix schenckii, which is widely distributed in nature, and presents a saprophytic mycelial form on plant debris and soil. The immunological mechanisms involved in the prevention and control of sporotrichosis are not yet fully understood. In this study, mice were studied after infection with Sporothrix schenckii. In the first week after infection, fungal loading increased and thence decreased drastically 14 days after infection. Analysis by immunoblotting showed that the sera of all mice tested had antibodies reacting only with a 70 kDa antigen, with predominance of IgG1 and IgG3. Taken together, our results show that antigens from S. schenckii induced a specific humoral response in infected mice.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.08.004
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  • 85
    Digitale Medien
    Digitale Medien
    N-acetyl-d-galactosamine/N-acetyl-d-glucosamine – recognizing lectin from the snail Cepaea hortensis: purification, chemical characterization, cloning and expression in E. coli (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: From the albumin gland of the snail Cepaea hortensis we isolated and characterized a new N-acetyl-d-galactosamine/N-acetyl-d-glucosamine (GalNAc/GlcNAc) specific lectin (CHA-II) which was purified by a combination of affinity chromatography on GalNAc-agarose and gel filtration. The purified native lectin was found to be a multimeric protein, as revealed by SDS–PAGE and MALDI-TOF analysis. In SDS–PAGE the denatured and reduced lectin showed two bands of molecular masses with 17 and 15.5 kDa which reacted equally with anti-CHA-II rabbit antiserum. The lectin was O- and N-glycosylated with [(Gal)2-Man]2-Man-GlcNAc-GlcNAc-Asn as a probable structure for the oligosaccharide. Isoelectric focusing revealed a heterogeneous protein of at least four bands around pH 8.7. Tryptic peptides of CHA-II were N-terminally sequenced and highly degenerated gene specific oligonucleotide primers (GSPs) had been constructed. Using total RNA isolated from albumin glands, cDNAs were produced by the running race technique. Specific PCR fragments were obtained by PCR using GSPs, the universal primer and 5′- or 3′-RACE-cDNAs. The amplified fragments were cloned into the vector pDrive and were sequenced. The resulting total cDNA sequence consisted of 496 base pairs including an open reading frame of 360 base pairs which encoded a protein of 120 amino acids. The protein carried a putative signal peptide. The mature protein was predicted to comprise 99 amino acid residues with a calculated molecular weight of 11,239 Da. The PCR fragment encoding the mature protein was cloned into the vector pQE30 and expressed in E. coli. Recombinant CHA-II lectin was produced as inclusion bodies and extracted by 6 M guanidine hydrochloride. After refolding, the recombinant CHA-II agglutinated specifically human red blood cells of groups A and AB. In immunodiffusion experiments using rabbit antiserum raised against the native lectin, the protein showed a precipitation line of identity with the native lectin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.08.006
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  • 86
    Digitale Medien
    Digitale Medien
    Prevalence of human herpesvirus-8 infection in HIV-positive patients with and without Kaposi's sarcoma in Hungary (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Human herpesvirus-8 (HHV-8) infection of 130 Hungarian HIV-positive individuals with or without Kaposi's sarcoma was investigated from 158 serum and 122 peripheral blood samples using anti-latency-associated nuclear antigen (LANA) indirect immunofluorescence assay (IFA), recombinant orf65 and orfK8.1 antigen enzyme-linked immunosorbent assays (ELISAs), Western blot assays and orf26 specific nested polymerase chain reaction (PCR). The overall prevalence of HHV-8 infection was found to be 31.5% (41/130) among the Hungarian HIV-positive patients. This seroprevalence rate is 7–11-fold higher than that of healthy HIV-negative blood donors in Hungary. The highest prevalence of HHV-8 infection (36.1%, 35/97) was observed in homo- or bisexual patients. Similar to the serologic results, HHV-8 DNA was not always detectable in all serial samples previously shown to be positive for HHV-8 DNA.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.08.012
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  • 87
    Digitale Medien
    Digitale Medien
    A role of mitogen and stress-activated protein kinase 1/2 in survival of lipopolysaccharide-stimulated RAW 264.7 macrophages (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The effect of inhibition of mitogen and stress-activated protein kinases 1/2 (MSK1/2) on lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells was investigated. Pretreatment with Ro 31-8220, an inhibitor of MSK1/2, induced cell death in LPS-stimulated RAW 264.7 cells. In contrast, calphostin C, another inhibitor of protein kinase C, did not cause cell death. Cell death was not mediated by the release of pro-inflammatory mediators from LPS-stimulated RAW 264.7 cells. Cell death was accompanied by DNA fragmentation and annexin V binding, suggesting apoptotic cell death. Further, several caspase inhibitors did not prevent LPS-induced cell death of Ro 31-8220-pretreated RAW 264.7 cells. Nuclear translocation of apoptosis-inducing factor (AIF) was detected in Ro 31-8220-pretreated cells after LPS stimulation. Cell death was due to mitochondrial damage. Ro 31–8220 exclusively inhibited the phosphorylation of cAMP-responsive element binding protein (CREB), a substrate of MSK1/2. RAW 264.7 cells transfected with the dominant-negative MSK1 clones underwent cell death in response to LPS. Hence, it was suggested that MSK1/2 might play a critical role in the survival of LPS-stimulated RAW 264.7 cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.09.007
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  • 88
    Digitale Medien
    Digitale Medien
    Editorial board (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/S0928-8244(05)00010-6
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  • 89
    Digitale Medien
    Digitale Medien
    Immunobiology of hookworm infection (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Hookworms infect almost one billion people and are a major cause of iron-deficiency anaemia in developing countries of the tropics. Despite their prevalence and the morbidity they cause, little is known about the immune response to this complex eukaryotic parasite. Recent publications have shed light on the human cellular immune responses to hookworms, as well as mechanisms that hookworms utilize to skew the immune response in its favour. Unlike most other human helminth infections, neither age- nor exposure-related immunity develops in the majority of infected people. A vaccine is therefore a highly desirable goal. To this end, gene sequencing efforts have resulted in the deposition of more than 10,000 hookworm cDNA sequences in the public domain, providing a molecular snapshot of this intriguing parasite and providing novel tools for the development of new control strategies. Significant progress has been made in the development of anti-hookworm recombinant vaccines, and clinical trials are expected to begin in the near future.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.11.006
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  • 90
    Digitale Medien
    Digitale Medien
    Notes to authors (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/S0928-8244(04)00254-8
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  • 91
    Digitale Medien
    Digitale Medien
    In vitro activation of chicken leukocytes and in vivo protection against Salmonella enteritidis organ invasion and peritoneal S. enteritidis infection-induced mortality in neonatal chickens by immunostimulatory CpG oligodeoxynucleotide (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Unmethylated CpG oligodinucleotides (CpG-ODN) flanked by specific bases found in bacterial DNA are known to stimulate innate immune responses. In this study, synthetic CpG-ODNs were evaluated for their in vitro stimulation of leukocyte and in vivo protection against Salmonella enteritidis (SE) in neonatal chickens. Our studies showed that CpG-ODN stimulated bactericidal activities, releasing granules (degranulation) and generating reactive oxygen species (oxidative burst), in chicken heterophils and up regulated nitric oxide production in chicken peripheral blood monocytes. When day-old chickens were given (i.p.) synthetic CpG-ODNs followed by oral challenge of SE, a significant reduction (p 〈 0.05) of organ invasion by SE was observed in chickens pretreated with CpG-ODN containing the immunostimulatory GTCGTT motif. This CpG-OND also significantly reduced mortality of chickens with acute peritoneal infection of SE. Our study provides evidence that immunostimulatory CpG-ODN stimulated innate immune activities and enhanced the resistance to infectious pathogens in neonatal chickens.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2004.07.009
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  • 92
    Digitale Medien
    Digitale Medien
    Corrigendum to: ‘Vaccination with Leishmania soluble antigen and immunostimulatory oligodeoxynucleotides induces specific immunity and protection against Leishmania donovani infection’ (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 43 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/rp10.1016-S0928-8244(03)00034-8
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  • 93
    Digitale Medien
    Digitale Medien
    Towards a molecular diagnosis of invasive aspergillosis and disseminated candidosis (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: A lot of in-house polymerase chain reaction assays have been reported for diagnosis of invasive aspergillosis and disseminated candidosis. Encouraging results have been published to anticipate the diagnosis over the conventional microbiological methods. However, the absence of standardized methods has led to diverging results. As a consequence, these tests are not recognized as consensual diagnostic criteria, in contrast with some antigenemia detection kits. The major breakthrough for improving the results of these methods is the emergence of real-time technologies. This markedly improves the reliability of the PCR results by dramatically decreasing the risk of false positive results due to PCR products carryover. Moreover, using the quantitative results provided by this technique, this allows to rapidly compare the efficiency of primers, probes, and DNA extraction methods. Therefore, the hope is to identify the more specific and sensitive parameters to implement comparative studies. Automated DNA extraction should also be useful to achieve this goal.Whatever sophisticated technology is used, we still have to define the meaning of detecting nucleic acids in a given clinical sample. This seems simple in normally sterile anatomical sites but less obvious for example in respiratory specimens for invasive aspergillosis or in blood for candidosis in heavily colonized patients. Additional studies of the kinetics of fungal DNA are needed. The development of real-time technology should improve our knowledge in order to give the clinicians informative clues for making a decision.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.05.012
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  • 94
    Digitale Medien
    Digitale Medien
    Biosynthesis of glycoproteins in the pathogenic fungus Candida albicans: Activation of dolichol phosphate mannose synthase by cAMP-mediated protein phosphorylation (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Following incubation with ATP and a cAMP-dependent protein kinase under optimal conditions of lipid acceptor, phospholipid and metal ion requirements, the transfer activity of partially purified dolichol phosphate mannose synthase (DPMS) increased about 60% and this activation correlated with a 50% increase in Vmax with no alteration in the apparent Km for GDP-Manose. Phosphorylation with [γ-32P]ATP resulted in the labeling of several polypeptides, one of which exhibited the molecular weight of the enzyme (30 kDa) and was also recognized using a specific anti-DPMS monoclonal antibody. This and the fact that the phosphate label could be removed by an alkaline phosphatase indicate that Candida DPMS may be regulated by phosphorylation–dephosphorylation, a mechanism that has been proposed for the enzyme in other organisms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.05.016
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  • 95
    Digitale Medien
    Digitale Medien
    Interaction of pathogenic fungi with host cells: Molecular and cellular approaches (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: This review provides an overview of several molecular and cellular approaches that are likely to supply insights into the host–fungus interaction. Fungi present intra- and/or extracellular host–parasite interfaces, the parasitism phenomenon being dependent on complementary surface molecules. The entry of the pathogen into the host cell is initiated by the fungus adhering to the cell surface, which generates an uptake signal that may induce its cytoplasmatic internalization. Furthermore, microbial pathogens use a variety of their surface molecules to bind to host extracellular matrix (ECM) components to establish an effective infection. On the other hand, integrins mediate the tight adhesion of cells to the ECM at sites referred to as focal adhesions and also play a role in cell signaling. The phosphorylation process is an important mechanism of cell signaling and regulation; it has been implicated recently in defense strategies against a variety of pathogens that alter host-signaling pathways in order to facilitate their invasion and survival within host cells. The study of signal transduction pathways in virulent fungi is especially important in view of their putative role in the regulation of pathogenicity. This review discusses fungal adherence, changes in cytoskeletal organization and signal transduction in relation to host–fungus interaction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.05.014
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  • 96
    Digitale Medien
    Digitale Medien
    Editorial: Molecular genetic approaches to the study of human pathogenic fungi (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.06.004
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  • 97
    Digitale Medien
    Digitale Medien
    Homology, disruption and phenotypic analysis of CaGS Candida albicans gene induced during macrophage infection (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: During macrophage infection Candida albicans expresses differentially several genes whose functions are associated with its survival strategy. Among others, we have isolated CaGS gene, which is homologous to SNF3, a glucose sensor of Saccharomyces cerevisiae. To elucidate its potential role during infection, CaGS has been disrupted and the resulting phenotype analyzed on different solid media. The null mutant lost the ability to form hyphae on a medium with low glucose concentration and serum. Furthermore, this mutant does not disrupt macrophage in in vitro infections. We believe that this putative glucose sensor is involved in hyphal development during macrophage infection.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.06.007
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  • 98
    Digitale Medien
    Digitale Medien
    Rapid molecular identification of Neisseria meningitidis isolates using the polymerase chain reaction followed by single-stranded conformation polymorphism analysis (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Typing of Neisseria meningitidis strains is currently performed with conventional and molecular methods. Our objectives were: first, to develop a polymerase chain reaction (PCR) followed by single-stranded conformation polymorphism (SSCP) analysis of the PorA gene (VR1 region) to distinguish N. meningitidis subtypes and second, to evaluate the method for the identification and characterization of N. meningitidis in patient specimens. SSCP analysis of the VR1 region of the PorA1/2 gene from 126 N. meningitidis strains and 29 clinical samples identified seven SSCP types (SP-1 to SP-7); four strains were not typeable by the method. Classification according to the SSCP methods and serosubtype agreed for 122 of the 126 typeable strains (96.8%). For the 24-culture positive clinical samples, serosubtype and SSCP agreed in all cases. Five samples, which were culture-negative but obtained from children during an apparent outbreak of meningococcal disease in a primary school, presented identical SSCP classification for each sample (SP-2). PCR-SSCP is a rapid and cost-effective method for typing N. meningitidis strains that could provide important early information in the surveillance of suspected meningococcal outbreaks, particularly when culture-negative specimens constitutes the main source of material to analyze.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.03.003
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  • 99
    Digitale Medien
    Digitale Medien
    Iron and iron chelating agents modulate Mycobacterium tuberculosis growth and monocyte-macrophage viability and effector functions (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Excess of iron promotes Mycobacterium tuberculosis infection, its replication and progression to clinical disease and death from tuberculosis. Chelation of iron may reduce M. tuberculosis replication, restore host defence mechanisms and it could constitute an application in the prevention and treatment strategies where both iron overload and tuberculosis are prevalent. We investigated the effect of iron and iron chelating agents, like desferrioxamine and silybin, individually and in combination with iron on mycobacterial number, viability in culture and after recovery from monocyte-macrophages, together with monocyte-macrophages viability and oxidative defence. Mycobacterial number and viability in culture were assessed using real-time quantitative PCR of H37Rv IS6110 DNA, 16S rRNA and 85B mRNA, whereas the microplate AlamarBlueTM assay was used to detect viability in culture post-infection. Mitochondrial membrane potential and phosphatidyl serine exposure of monocyte-macrophages, detected using Mitotracker Red fluorescence and Annexin V binding, respectively, served as indicators of host cell viability. Superoxide generation served as marker of monocyte-macrophage effector functions. Extracellular H37Rv showed a significant increase in number and viability in presence of excess iron and, by large, a significant decrease in number and viability in presence of the iron chelating agents, silybin and desferrioxamine, compared to cultivation without supplementation. Intracellularly, excess iron increased H37Rv viability significantly but reduced monocyte-macrophages mitochondrial membrane potential and compromised superoxide production. Desferrioxamine had little influence on intracellular parameters, but consistently prevented effects of excess iron, while silybin significantly altered most intracellular parameters and mostly failed to prevent effects of excess iron. These findings suggest that chelation therapy should be considered in conditions of iron overload and that effective chelating agents like desferrioxamine, with limited intracellular access might need to be used in combination with lypophilic chelating agents.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.02.007
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  • 100
    Digitale Medien
    Digitale Medien
    The influence of microbial metabolites on human intestinal epithelial cells and macrophages in vitro (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 45 (2005), S. 0 
    Details
    ISSN: 1574-695X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Microbial metabolites may influence the metabolic integrity of intestinal epithelial cells and induce mucosal immune responses. Therefore, we investigated the effects of the microbial metabolites butyrate, iso-valerate, and ammonium on Caco-2 cells and macrophages. Barrier functioning was determined by measuring transepithelial electrical resistance and basolateral recoveries of metabolites. The barrier function of Caco-2 cells remained intact after exposures. Basolateral recoveries ranged from 6.2% to 15.2%. Tumour necrosis factor-α and interleukin-10 were measured to determine immune reactions. The Caco-2 cells did not secrete both cytokines. Physiological concentrations of butyrate and iso-valerate stimulated the secretion of tumour necrosis factor-α and suppressed the secretion of interleukin-10 by macrophages that are not protected by an epithelial barrier. In contrast, ammonium concentrations as high as those produced by microbiotas of IBD patients suppressed the release of both cytokines when the barrier function is impaired.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/j.femsim.2005.03.010
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