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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 4031-4033 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A fiber-optic sensor for weak interaction measuring of the electric field intensity in microwave fields is presented. The most remarkable features of the sensor are a low isotropy error, a good selectivity between the electric and magnetic field component, a high sensitivity, low field distortions, and inexpensive fabrication. A tiny microwave absorber mounted at the end of an optical fiber changes its temperature according to the electric field intensity. The absorber temperature is measured by making use of the optical transmittivity variation of a semiconductor element. A simple evaluation of the optical attenuation leads to a readout which is proportional to the square of the electric field strength. In order to overcome the problems due to fiber bend losses a mode acceptance filter is described. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1523-5378
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background. Availability of the essential nutrient iron is thought to vary greatly in the gastric mucosa, and thus the human gastric pathogen Helicobacter pylori requires regulatory responses to these environmental changes. Bacterial iron-responsive regulation is often mediated by Ferric Uptake Regulator (Fur) homologs, and in this study we have determined the role of H. pylori Fur in regulation of H. pylori iron uptake.Methods. Wild-type H. pylori and fur mutant derivatives were compared after growth in iron-restricted and iron-replete conditions. Iron-uptake was measured using 55Fe-labeled iron, whereas gene expression was monitored at the transcriptional level using Northern hybridization and lacZ reporter gene fusions.Results. Iron-uptake and total cellular iron content were approximately five-fold increased in the fur mutant compared with the wild-type strain, which indicated that in the fur mutant iron-uptake is not repressed by excess iron. A comprehensive screening of all H. pylori genes encoding putative iron-uptake proteins indicated that some of these H. pylori genes are constitutively expressed, while others are iron- and Fur-regulated.Conclusions. Iron uptake in H. pylori is in part differently regulated compared with other bacteria, since in H. pylori some iron-uptake systems are constitutively expressed. However, other iron uptake systems of H. pylori display the iron- and Fur-mediated repression that is common in bacteria. Taken together, this Fur-mediated modulation of iron-uptake capacity may be a specific adaptation to the conditions in the human stomach, where iron starvation and iron overload can be encountered in relatively short time intervals.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Helicobacter 9 (2004), S. 0 
    ISSN: 1523-5378
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This paper reviews the new literature from the past year on the association between colonization with Helicobacter pylori and non-malignant disease of the upper gastrointestinal tract. This issue has, in the past year, remained a topic of wide research interest yielding many important new data. These data show that H. pylori eradication is the most effective therapy for peptic ulcer disease, but that a considerable proportion of ulcer patients remain to have dyspeptic symptoms. The discussion on the interaction between H. pylori and NSAID use in the etiology of ulcer disease has not yet been settled. Several studies, both from Asia and Europe, now reported that H. pylori eradication has a minimal effect on the primary prevention of ulcer disease in NSAID users, but eradication appears of relevance for the secondary prevention of ulcer disease in addition to proton pump inhibitor maintenance therapy. Various studies brought further support for the hypothesis that H. pylori eradication is of some benefit for patients with non-ulcer dyspepsia, although the effects are limited. The prevalence of H. pylori is lower among GERD patients than among controls, but H. pylori eradication has not been consistently shown to increase the risk for the newly development of GERD in an individual subject undergoing H. pylori eradication. The discussion on H. pylori and GERD should not preclude us from treating H. pylori-infected patients for accepted clinical indications. In patients using proton pump inhibitors for GERD, H. pylori eradication leads to a resolution of their corpus-predominant pangastritis, without impairing the efficacy of PPI therapy.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1523-5378
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background.  Helicobacter pylori factors that contribute to disease outcome are largely unknown, but intimate contact with host cells mediated by outer membrane proteins is thought to play an important role. Expression of the outer membrane proteins OipA, HopZ, SabA, and SabB is regulated by phase-variable dinucleotide repeats in the coding regions of the respective genes. We have evaluated the correlation between the expression status of these four genes and disease outcome of H. pylori infection in a Dutch patient population.Materials and Methods.  H. pylori strains, isolated from 96 Dutch patients with gastritis (n = 29), duodenal ulcer (n = 28), gastric ulcer (n = 21), gastric carcinoma (n = 9), and lymphoma (n = 9), were analyzed for the ‘on/off’ expression status of the H. pylori genes oipA, hopZ, sabA, and sabB by direct DNA sequence analysis of amplified fragments.Results.  The off-status of sabB was significantly associated with duodenal ulcer (p = .036), but not with gastric ulcer. In contrast, the expression status of oipA, hopZ, and sabA did not correlate with disease outcome. Furthermore, lymphoma strains appeared to express a significantly smaller amount of putative adhesins when compared to gastritis, gastric ulcer, duodenal ulcer and gastric carcinoma strains (p 〈 .02 for all groups tested).Conclusion.  The off-status of sabB was found to be associated with duodenal ulcer disease, and thus represents a putative marker for disease outcome. Assuming that SabB is involved in bacterial adhesion, this association suggests that adherent H. pylori are more prone to elimination by the host immune system.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry 4 (1912), S. 114-118 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1523-5378
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Helicobacter pylori persists in the human stomach for decades. This requires an efficient adaptation of H. pylori to the gastric niche and involves the regulation of bacterial genes in response to environmental stress. Efficient molecular tools to identify regulated H. pylori genes are scarce, therefore we developed a genomic lacZ reporter gene fusion system in H. pylori to screen for stress-regulated genes.〈section xml:id="abs1-3"〉〈title type="main"〉Materials and methods.The integration vector pBW was constructed and used to generate random genomic lacZ fusions in H. pylori. Two-hundred-and-fifty H. pylori transformants were selected from this library, replica-plated and screened for differential lacZ expression after exposure to two environmental stress conditions: increased temperature (42°C), and iron-limitation.〈section xml:id="abs1-4"〉〈title type="main"〉Results.From a library of H. pylori transformants with random genomic transcriptional lacZ fusions, two stress-regulated H. pylori loci were identified. The transcription of a gene of unknown function (designated hsp12) was increased by incubation at 42°C. The transcription of a locus, consisting of the three fumarate reductase subunit genes (frdCAB) and the HP0190 gene from H. pylori strain 26695, was decreased under iron-limitation.〈section xml:id="abs1-5"〉〈title type="main"〉Conclusions.This is the first time that a genomic transcriptional lacZ reporter gene H. pylori library has been used as a tool for the fast and efficient identification of environmental stress-regulated H. pylori genes.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1546-170X
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] The immune response to adenoviral vectors can induce inflammation and loss of transgene expression in transfected tissues. This would limit the use of adenovirus-mediated gene transfer in disease states in which long-term gene expression is required. While studying the effect of the ...
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 28 (2000), S. 0 
    ISSN: 1574-695X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The level of the IgG antibody titer against Helicobacter pylori correlates with the severity of gastritis. H. pylori strains can harbor the so-called pathogenicity island, containing the cytotoxin associated gene (cagA). Since cagA-positive strains are more virulent it can be postulated that the gastritis will be more severe and hence the IgG antibody titer higher. In a cross-sectional study the correlation of IgG antibody titer and cagA status was studied from patients undergoing upper gastrointestinal endoscopy. Biopsy specimens were obtained to determine the H. pylori status. In addition a serum sample was taken for detection of IgG antibodies against H. pylori as well as CagA. A total of 290 patients positive for IgG antibodies against H. pylori were included. Of these 153 were cagA-positive and 137 were cagA-negative. The mean IgG antibody titer was significantly higher in cagA-positive patients compared to cagA-negatives, 0.75 (S.D. 0.22) versus 0.69 (S.D. 0.24) (P=0.033). It is concluded that the IgG antibody titer is significantly higher in patients harboring cagA-positive H. pylori strains. However, in daily practice the level in IgG antibody titer cannot predict whether or not an individual carries a cagA-positive H. pylori strain since major overlap in IgG antibody titer between cagA-positive and cagA-negative patients is present.
    Type of Medium: Electronic Resource
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