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  • 1
    Publication Date: 2013-02-21
    Description: Bacillus cereus strains harboring a pXO1-like virulence plasmid cause respiratory anthrax-like disease in humans, particularly in welders. We developed mouse models for intraperitoneal as well as aerosol challenge with spores of B. cereus G9241, harboring pBCXO1 and pBC218 virulence plasmids. Compared to wild-type B. cereus G9241, spores with a deletion of the pBCXO1-carried protective antigen gene ( pagA1 ) were severely attenuated, whereas spores with a deletion of the pBC218-carried protective antigen homologue ( pagA2 ) were not. Anthrax vaccine adsorbed (AVA) immunization raised antibodies that bound and neutralized the pagA1 -encoded protective antigen (PA1) but not the PA2 orthologue encoded by pagA2 . AVA immunization protected mice against a lethal challenge with spores from B. cereus G9241 or B. cereus Elc4, a strain that had been isolated from a fatal case of anthrax-like disease. As the pathogenesis of B. cereus anthrax-like disease in mice is dependent on pagA1 and PA-neutralizing antibodies provide protection, AVA immunization may also protect humans from respiratory anthrax-like death.
    Print ISSN: 0019-9567
    Electronic ISSN: 1098-5522
    Topics: Medicine
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  • 2
    Publication Date: 2015-07-09
    Print ISSN: 1045-2249
    Electronic ISSN: 1465-7279
    Topics: Biology
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  • 3
    Publication Date: 2013-01-03
    Description: The spectra of several high-redshift ( z 〉 6) quasars have shown indications for a Gunn–Peterson (GP) damping wing, suggesting a substantial mean neutral hydrogen fraction ( $\bar{x}_{\rm H\,{\scriptscriptstyle I}}^{\rm IGM}\gtrsim 0.03$ ) in the z 6 intergalactic medium (IGM). However, previous analyses assumed that the IGM was uniformly ionized outside of the quasar’s H  ii region. Here we relax this assumption and model patchy reionization scenarios for a range of IGM and quasar parameters. Compared to uniform reionization, patchy reionization imprints a different average damping wing profile with an associated sightline-to-sightline scatter. We quantify the impact of these differences on the inferred $\bar{x}_{\rm H\,{\scriptscriptstyle I}}^{\rm IGM}$ , by fitting the spectra of three quasars: SDSS J1148+5251 ( z = 6.4189), J1030+0524 ( z = 6.308) and J1623+3112 ( z = 6.247). We find that the best-fitting values of $\bar{x}_{\rm H\,{\scriptscriptstyle I}}^{\rm IGM}$ in the patchy models agree well with the uniform case. More importantly, we confirm that the observed spectra favour the presence of a GP damping wing, with peak likelihoods decreasing by factors of few–10 when the spectra are modelled without a damping wing. We also find that the Lyα absorption spectra, by themselves, cannot distinguish the damping wing in a relatively neutral IGM from a damping wing in a highly ionized IGM, caused either by an isolated neutral patch or by a damped Lyα absorber (DLA). However, neutral patches in a highly ionized universe ( $\bar{x}_{\rm H\,{\scriptscriptstyle I}}^{\rm IGM}\lesssim 10^{-2}$ ) and DLAs with the large required column densities ( $N_{\rm H\,{\small I}}\gtrsim {\rm { few}}\times 10^{20}{\rm { cm}^{-2}}$ ) are both rare. As a result, when we include reasonable prior probabilities for the line of sight (LOS) to intercept either a neutral patch or a DLA at the required distance of ~ 40-60 comoving Mpc away from the quasar, we find strong lower limits on the neutral fraction in the IGM, $\bar{x}_{\rm H\,{\scriptscriptstyle I}}^{\rm IGM}\gtrsim 0.1$ (at 95 per cent confidence). This supports earlier claims that a substantial global fraction of hydrogen in the z 6 IGM is in neutral form.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 4
    Publication Date: 2012-09-06
    Description: Nonpigmented Yersinia pestis ( pgm ) strains are defective in scavenging host iron and have been used in live-attenuated vaccines to combat plague epidemics. Recently, a Y. pestis pgm strain was isolated from a researcher with hereditary hemochromatosis who died from laboratory-acquired plague. We used hemojuvelin-knockout ( Hjv –/– ) mice to examine whether iron-storage disease restores the virulence defects of nonpigmented Y. pestis . Unlike wild-type mice, Hjv –/– mice developed lethal plague when challenged with Y. pestis pgm strains. Immunization of Hjv –/– mice with a subunit vaccine that blocks Y. pestis type III secretion generated protection against plague. Thus, individuals with hereditary hemochromatosis may be protected with subunit vaccines but should not be exposed to live-attenuated plague vaccines.
    Print ISSN: 0022-1899
    Electronic ISSN: 1537-6613
    Topics: Medicine
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  • 5
    Publication Date: 2015-11-11
    Description: Many pathogens usurp the host hemostatic system during infection to promote pathogenesis. Yersinia pestis , the causative agent of plague, expresses the plasminogen activator protease Pla, which has been shown in vitro to target and cleave multiple proteins within the fibrinolytic pathway, including the plasmin inhibitor α2-antiplasmin (A2AP). It is not known, however, if Pla inactivates A2AP in vivo ; the role of A2AP during respiratory Y. pestis infection is not known either. Here, we show that Y. pestis does not appreciably cleave A2AP in a Pla-dependent manner in the lungs during experimental pneumonic plague. Furthermore, following intranasal infection with Y. pestis , A2AP-deficient mice exhibit no difference in survival time, bacterial burden in the lungs, or dissemination from wild-type mice. Instead, we found that in the absence of Pla, A2AP contributes to the control of the pulmonary inflammatory response during infection by reducing neutrophil recruitment and cytokine production, resulting in altered immunopathology of the lungs compared to A2AP-deficient mice. Thus, our data demonstrate that A2AP is not significantly affected by the Pla protease during pneumonic plague, and although A2AP participates in immune modulation in the lungs, it has limited impact on the course or ultimate outcome of the infection.
    Print ISSN: 0019-9567
    Electronic ISSN: 1098-5522
    Topics: Medicine
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  • 6
    Publication Date: 2015-12-29
    Description: Pneumonic plague represents the most severe form of disease caused by Yersinia pestis due to its ease of transmission, rapid progression, and high mortality rate. The Y. pestis outer membrane Pla protease is essential for the development of pneumonic plague; however, the complete repertoire of substrates cleaved by Pla in the lungs is not known. In this study, we describe a proteomic screen to identify host proteins contained within the bronchoalveolar lavage fluid of mice that are cleaved and/or processed by Y. pestis in a Pla-dependent manner. We identified peroxiredoxin 6 (Prdx6), a host factor that contributes to pulmonary surfactant metabolism and lung defense against oxidative stress, as a previously unknown substrate of Pla. Pla cleaves Prdx6 at three distinct sites, and these cleavages disrupt both the peroxidase and phospholipase A 2 activities of Prdx6. In addition, we found that infection with wild-type Y. pestis reduces the abundance of extracellular Prdx6 in the lungs compared to that after infection with pla Y. pestis , suggesting that Pla cleaves Prdx6 in the pulmonary compartment. However, following infection with either wild-type or pla Y. pestis , Prdx6-deficient mice exhibit no differences in bacterial burden, host immune response, or lung damage from wild-type mice. Thus, while Pla is able to disrupt Prdx6 function in vitro and reduce Prdx6 levels in vivo , the cleavage of Prdx6 has little detectable impact on the progression or outcome of pneumonic plague.
    Print ISSN: 0019-9567
    Electronic ISSN: 1098-5522
    Topics: Medicine
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  • 7
    Publication Date: 2016-02-16
    Description: We employed a semi-Markov multistate model for the simultaneous analysis of various endpoints describing the course of breast cancer. Results were compared with those from standard analyses using a Cox proportional hazards model. We included 3,012 patients with invasive breast cancer newly diagnosed between 2001 and 2005 who were recruited in Germany for a population-based study, the Mamma Carcinoma Risk Factor Investigation (MARIE Study), and prospectively followed up until the end of 2009. Locoregional recurrence and distant metastasis were included as intermediate states, and deaths from breast cancer, secondary cancer, and other causes were included as competing absorbing states. Tumor characteristics were significantly associated with all breast cancer–related endpoints. Nodal involvement was significantly related to local recurrence but more strongly related to distant metastases. Smoking was significantly associated with mortality from second cancers and other causes, whereas menopausal hormone use was significantly associated with reduced distant metastasis and death from causes other than cancer. The presence of cardiovascular disease at diagnosis was solely associated with mortality from other causes. Compared with separate Cox models, multistate models allow for dissection of prognostic factors and intermediate events in the analysis of cause-specific mortality and can yield new insights into disease progression and associated pathways.
    Print ISSN: 0002-9262
    Electronic ISSN: 1476-6256
    Topics: Medicine
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  • 8
    Publication Date: 2012-08-15
    Description: Aims Dynamic three-dimensional-cardiac magnetic resonance (3D-CMR) perfusion proved highly diagnostic for the detection of angiographically defined coronary artery disease (CAD) and has been used to assess the efficacy of coronary stenting procedures. The present study aimed to relate significant coronary lesions as assessed by fractional flow reserve (FFR) to the volume of myocardial hypoenhancement on 3D-CMR adenosine stress perfusion imaging and to define the inter-study reproducibility of stress inducible 3D-CMR hypoperfusion. Methods and results A total of 120 patients with known or suspected CAD were examined in two CMR centres using 1.5 T systems. The protocol included cine imaging, 3D-CMR perfusion during adenosine infusion, and at rest followed by delayed enhancement (DE) imaging. Fractional flow reserve was recorded in epicardial coronary arteries and side branches with ≥2 mm luminal diameter and 〉40% severity stenosis (pathologic FFR 〈 0.75). Twenty-five patients underwent an identical repeat CMR examination for the determination of inter-study reproducibility of 3D-CMR perfusion deficits induced by adenosine. Three-dimensional CMR perfusion scans were visually classified as pathologic if one or more segments showed an inducible perfusion deficit in the absence of DE. Myocardial ischaemic burden (MIB) was measured by segmentation of the area of inducible hypoenhancement and normalized to left ventricular myocardial volume (MIB, %). Three-dimensional CMR perfusion resulted in a sensitivity, specificity, and diagnostic accuracy of 90, 82, and 87%, respectively. Substantial concordance was found for inter-study reproducibility [Lin's correlation coefficient: 0.98 (95% confidence interval: 0.96–0.99)]. Conclusion Three-dimensional CMR stress perfusion provided high diagnostic accuracy for the detection of functionally significant CAD. Myocardial ischaemic burden measurements were highly reproducible and allowed the assessment of CAD severity.
    Print ISSN: 0195-668X
    Electronic ISSN: 1522-9645
    Topics: Medicine
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  • 9
    Publication Date: 2014-04-29
    Description: Potassium (K + )-uptake transport proteins present in prokaryote and eukaryote cells are categorized into two classes; Trk/Ktr/HKT, K + channel, and Kdp belong to the same superfamily, whereas the remaining K + -uptake family, Kup/HAK/KT has no homology to the others, and neither its membrane topology nor crucial residues for K + uptake have been identified. We examined the topology of Kup from Escherichia coli . Results from the reporter fusion and cysteine labeling assays support a model with 12 membrane-spanning domains. A model for proton-coupled K + uptake mediated by Kup has been proposed. However, this study did not show any stimulation of Kup activity at low pH and any evidence of involvement of the three His in Kup-mediated K + uptake. Moreover, replacement of all four cysteines of Kup with serine did not abolish K + transport activity. To gain insight on crucial residues of Kup-mediated K + uptake activity, we focused on acidic residues in the predicted external and transmembrane regions, and identified four residues in the membrane regions required for K + uptake activity. This is different from no membrane-localized acidic residues essential for Trk/Ktr/HKTs, K + channels and Kdp. Taken together, these results demonstrate that Kup belongs to a distinct type of K + transport system.
    Print ISSN: 0021-924X
    Electronic ISSN: 1756-2651
    Topics: Biology , Chemistry and Pharmacology
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