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Salomonsson E.N.,Swedish Defence Research Agency | Forslund A.-L.,Swedish Defence Research Agency | Forsberg A.,Umea Center for Microbial Research
Frontiers in Microbiology | Year: 2011

Francisella tularensis is a highly virulent intracellular human pathogen that is capable of rapid proliferation in the infected host. Mutants affected in intracellular survival and growth are highly attenuated which highlights the importance of the intracellular phase of the infection. Genomic analysis has revealed that Francisella encodes all genes required for expression of functional type IV pili (Tfp), and in this focused review we summarize recent findings regarding this system in the pathogenesis of tularemia. Tfp are dynamic adhesive structures that have been identified as major virulence determinants in several human pathogens, but it is not obvious what role these structures could have in an intracellular pathogen like Francisella. In the human pathogenic strains, genes required for secretion and assembly of Tfp and one pilin, PilA, have shown to be required for full virulence. Importantly, specific genetic differences have been identified between the different Francisella subspecies where in the most pathogenic type A variants all genes are intact while several Tfp genes are pseudogenes in the less pathogenic type B strains. This suggests that there has been a selection for expression of Tfp with different properties in the different subspecies. There is also a possibility that the genetic differences reflect adaptation to different environmental niches of the subspecies and plays a role in transmission of tularemia. This is also in line with recent findings where Tfp pilins are found to be glycosylated which could reflect a role for Tfp in the environment to promote survival and transmission. We are still far from understanding the role of Tfp in virulence and transmission of tularemia, but with the genomic information and genetic tools available we are in a good position to address these issues in the future. © 2011 Näslund Salomonsson,Forslund and Forsberg. Source


Bui H.T.B.,Can Tho University | Ha Q.T.K.,Seoul National University | Oh W.K.,Seoul National University | Vo D.D.,Umea University | And 7 more authors.
Tetrahedron Letters | Year: 2016

Twelve new 2-quinolizinylbenzimidazole and 2-naphthalylbenzimidazole derivatives with various 5- and 6-positioned substituents (aza, H, CH3, Cl, NO2, NH2, OCH3), have been synthesized in moderate to excellent yields via the condensation of 4-oxo-4H-quinolizinecarbaldehyde or naphthalenecarbaldehyde with substituted o-phenylenediamines, o-nitroaniline, and 2,3-pyridinediamine using sodium metabisulfite or sodium hydrosulfite under microwave irradiation. The new benzimidazole derivatives were screened for their cytotoxic activity against the human breast cancer cell line (MCF-7). The results showed on one hand that 2-(substituted quinolizinyl)-1H-benzimidazoles (12b-f) were less active (3-6 fold) than the positive control Tamoxifen (CC50 = 6.52 μM), and on the other hand, among the 2-(substituted naphthalyl)-1H-benzimidazoles series (13a-f), compounds 6,7,8-trimethoxy-3-(5-chloro-1H-benzo[d]imidazol-2-yl)naphthalen-1-ol (13c) (CC50 = 7.48 μM) and 6,7,8-trimethoxy-3-(5-methoxy-1H-benzo[d]imidazol-2-yl)naphthalen-1-ol (13f) (CC50 = 6.43 μM) were found to be as active as Tamoxifen. © 2016 Elsevier Ltd. All rights reserved. Source


Bui H.T.B.,Can Tho University | Vo D.D.,Umea University | Vo D.D.,Umea Center for Microbial Research | Chau Y.N.T.,Vinh University | And 3 more authors.
Synthetic Communications | Year: 2015

A facile synthetic method for the construction of 2-substituted-4-oxo-4H-quinolizine-based core structure has been successfully developed. The synthesis made use of a one-pot Stobbe condensation followed by cyclization starting from the commercially available 2-pyridinecarbaldehyde. The structure of the formed 4-oxo-4H-quinolizine-2-carboxylate was fully confirmed by mass spectra, 1H NMR and 13C NMR, correlation spectrography, heteronuclear multiple bond correlation, and heteronuclear single quantum coherence (HSQC) spectra. The ethyl carboxylate moiety was then further functionalized via direct aminolysis by a range of amines to afford the corresponding 4-oxo-4H-quinolizine-2-carboxamides 4a-i in moderate to good yields. Copyright © Taylor & Francis Group, LLC. Source


Andersson C.,Umea University | Gripenland J.,Umea University | Gripenland J.,Karolinska University Hospital | Johansson J.,Umea University | Johansson J.,Umea Center for Microbial Research
Nature Protocols | Year: 2015

Microbial infections are a global health problem, particularly as microbes are continually developing resistance to antimicrobial treatments. An effective and reliable method for testing the virulence of different microbial pathogens is therefore a useful research tool. This protocol describes how the chicken embryo can be used as a trustworthy, inexpensive, ethically desirable and quickly accessible model to assess the virulence of the human bacterial pathogen Listeria monocytogenes, which can also be extended to other microbial pathogens. We provide a step-by-step protocol and figures and videos detailing the method, including egg handling, infection strategies, pathogenicity screening and isolation of infected organs. From the start of incubation of the fertilized eggs, the protocol takes <4 weeks to complete, with the infection part taking only 3 d. We discuss the appropriate controls to use and potential adjustments needed for adapting the protocol for other microbial pathogens. © 2015 Nature America, Inc. All rights reserved. Source


Surowiec I.,Umea University | Orikiiriza J.,Makerere University | Orikiiriza J.,Trinity College Dublin | Karlsson E.,Umea University | And 10 more authors.
Open Forum Infectious Diseases | Year: 2015

Background. Accuracy in malaria diagnosis and staging is vital to reduce mortality and post infectious sequelae. In this study, we present a metabolomics approach to diagnostic staging of malaria infection, specifically Plasmodium falciparum infection in children. Methods. A group of 421 patients between 6 months and 6 years of age with mild and severe states of malaria with age-matched controls were included in the study, 107, 192, and 122, individuals, respectively. A multivariate design was used as basis for representative selection of 20 patients in each category. Patient plasma was subjected to gas chromatography-mass spectrometry analysis, and a full metabolite profile was produced from each patient. In addition, a proof-of-concept model was tested in a Plasmodium berghei in vivo model where metabolic profiles were discernible over time of infection. Results. A 2-component principal component analysis revealed that the patients could be separated into disease categories according to metabolite profiles, independently of any clinical information. Furthermore, 2 subgroups could be identified in the mild malaria cohort who we believe represent patients with divergent prognoses. Conclusions. Metabolite signature profiling could be used both for decision support in disease staging and prognostication. © The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Societyof America. Source

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