SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Noppa Laila) "

Sökning: WFRF:(Noppa Laila)

  • Resultat 1-22 av 22
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  •  
2.
  • Andersson, Henrik, et al. (författare)
  • T A microarray analysis of the murine macrophage response to infection with Francisella tularensis LVS
  • 2006
  • Ingår i: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 55:8, s. 1023-1033
  • Tidskriftsartikel (refereegranskat)abstract
    • The response of cells of the mouse macrophage cell line J774 to infection with Francisella tularensis LVS was analysed by means of a DNA microarray representing approximately 18 500 genes (20 600 clones). The adaptive response was modest at all time points, and at most, 81 clones were differentially regulated from the time point of uptake of bacteria (0 min) up to 240 min later. For all five time points, 229 clones fulfilled the criteria of being differentially regulated, i.e. the ratio between infected versus non-infected cells was at least 1.7-fold up- or down-regulated and P <0.05. It was found that many of the differentially regulated genes are known to respond to stress in general and to oxidative stress specifically. However, at 120 min it was observed that genes that lead to depletion of glutathione were upregulated. Possibly, this was a result of mechanisms induced by F. tularensis. Generally, there was a conspicuous lack of inflammatory responses and, for example, although tumour necrosis factor alpha (TNF-α) was upregulated at 0 min, a significant down-regulation was noted at all subsequent time points. When cells were treated with an inhibitor of inducible nitric oxide synthase (iNOS) or the antioxidant N-acetylcysteine (NAC), the infection-induced cytopathogenic effect was significantly inhibited. Together, the results suggest that F. tularensis LVS infection confers an oxidative stress upon the target cells and that many of the host-defence mechanisms appear to be intended to counteract this stress. The infection is characterized by a very modest inflammatory response.
  •  
3.
  • Forslund, Anna-Lena, 1964-, et al. (författare)
  • Direct repeat-mediated deletion of a type IV pilin gene results in major virulence attenuation of Francisella tularensis
  • 2006
  • Ingår i: Molecular Microbiology. - : Wiley-Blackwell. - 0950-382X .- 1365-2958. ; 59:6, s. 1818-1830
  • Tidskriftsartikel (refereegranskat)abstract
    • Francisella tularensis, the causative agent of tularaemia, is a highly infectious and virulent intracellular pathogen. There are two main human pathogenic subspecies, Francisella tularensis ssp. tularensis (type A), and Francisella tularensis ssp. holarctica (type B). So far, knowledge regarding key virulence determinants is limited but it is clear that intracellular survival and multiplication is one major virulence strategy of Francisella. In addition, genome sequencing has revealed the presence of genes encoding type IV pili (Tfp). One genomic region encoding three proteins with signatures typical for type IV pilins contained two 120 bp direct repeats. Here we establish that repeat-mediated loss of one of the putative pilin genes in a type B strain results in severe virulence attenuation in mice infected by subcutaneous route. Complementation of the mutant by introduction of the pilin gene in cis resulted in complete restoration of virulence. The level of attenuation was similar to that of the live vaccine strain and this strain was also found to lack the pilin gene as result of a similar deletion event mediated by the direct repeats. Presence of the pilin had no major effect on the ability to interact, survive and multiply inside macrophage-like cell lines. Importantly, the pilin-negative strain was impaired in its ability to spread from the initial site of infection to the spleen. Our findings indicate that this putative pilin is critical for Francisella infections that occur via peripheral routes.
  •  
4.
  •  
5.
  • Forslund, Anna-Lena, 1964-, et al. (författare)
  • The type IV pilin, PilA, is required for full virulence of Francisella tularensis subspecies tularensis
  • Annan publikation (populärvet., debatt m.m.)abstract
    • Background: All four Francisella tularensis subspecies possess gene clusters with potential to express type IV pili (Tfp). These clusters include putative pilin genes, as well as pilB, pilC and pilQ, required for secretion and assembly of Tfp. A hallmark of Tfp is the ability to retract the pilus upon surface contact, a property mediated by the ATPase PilT. Interestingly, out of the two major human pathogenic subspecies only the highly virulent type A strains have a functional pilT gene.Results: In a previous study, we were able to show that one pilin gene, pilA, was essential for virulence of a type B strain in a mouse infection model. In this work we have examined the role of several pilin genes in the virulence of the pathogenic type A strain SCHU S4. pilA, pilC, pilQ, and pilT were mutated by in-frame deletion mutagenesis. Interestingly, when mice were infected with a mixture of each mutant strain and the wild-type strain, the pilA, pilC and pilQ mutants were out-competed, while the pilT mutant was equally competitive as the wild-type.Conclusions: This suggests that expression and surface localisation of PilA contribute to virulence in the highly virulent type A strain, while PilT was dispensable for virulence in the mouse infection model.
  •  
6.
  •  
7.
  • Gylfe, Åsa, et al. (författare)
  • Isolation of Lyme disease Borrelia from puffins (Fratercula arctica) and seabird ticks (Ixodes uriae) on the Faeroe Islands
  • 1999
  • Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 37:4, s. 890-896
  • Tidskriftsartikel (refereegranskat)abstract
    • This is the first report on the isolation of Lyme disease Borrelia from seabirds on the Faeroe Islands and the characteristics of its enzootic cycle. The major components of the Borrelia cycle include the puffin (Fratercula arctica) as the reservoir and Ixodes uriae as the vector. The importance of this cycle and its impact on the spread of human Lyme borreliosis have not yet been established. Borrelia spirochetes isolated from 2 of 102 sampled puffins were compared to the borreliae previously obtained from seabird ticks, I. uriae. The rrf-rrl intergenic spacer and the rrs and the ospC genes were sequenced and a series of phylogenetic trees were constructed. Sequence data and restriction fragment length polymorphism analysis grouped the strains together with Borrelia garinii. In a seroepidemiological survey performed with residents involved in puffin hunting on the Faeroe Islands, 3 of 81 serum samples were found to be positive by two commonly used clinical tests: a flagellin-based enzyme-linked immunosorbent assay (ELISA) and Western blotting. These three positive serum samples also had high optical density values in a whole-cell ELISA. The finding of seropositive Faeroe Islanders who are regularly exposed to I. uriae indicate that there may be a transfer of B. garinii by this tick species to humans.
  •  
8.
  •  
9.
  • Jaenson, Thomas G. T., et al. (författare)
  • The ecology of lyme borreliosis in Sweden
  • 1994. - 1
  • Ingår i: Lyme borreliosis. - New York : Springer-Verlag New York. - 9781461524151 ; , s. 113-115
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • The geographical distribution of Lyme borreliosis (Lb) in the North European countries appears to coincide with the geographical distribution of the principal vector, the common tick Ixodes ricinus. We have found that in Sweden this tick species occurs in the southern and south-central parts of the country and along the coast of northern Sweden. This area corresponds with the distributional area of Lyme borreliosis. I. ricinus, and thus also Borrelia burgdorferi s.l., are in general not present in the interior of North Sweden, presumably because the climate is too harsh for the vector.
  •  
10.
  • Johansson, Anna-Lena, et al. (författare)
  • Francisella
  • 2015. - 2
  • Ingår i: Molecular medical microbiology. - : Academic Press. - 9780123971692 - 9780123977632 ; , s. 1991-2009
  • Bokkapitel (refereegranskat)abstract
    • Francisella tularensis, the causative agent of tularaemia, is a zoonotic intracellular pathogen that can be found in a very large number of species ranging from large mammals and vertebrates to invertebrates, arthropods and amoebas. Disease in humans often occurs in parallel with tularaemia in wild animals. Human infection can occur through aerosolization, direct contact with infected animals via arthropod vectors like ticks, mosquitos and biting flies. F. tularensis subspecies tularensis (type A) is one of the most infectious bacteria known and inhalation of as few as ten organisms can be sufficient to establish an infection in humans that if left untreated could be fatal. The success of F. tularensis as a pathogen lies in its unique ability to adapt a lifestyle as an intracellular pathogen and to very timely subvert host defences both at extracellular and intracellular levels. Key events in the infection process are the ability to rapidly escape the phagosome after uptake by phagocytic cells and the ability to replicate to high levels inside the host cells without evoking a host inflammatory response.
  •  
11.
  • Li, Xiaonan, et al. (författare)
  • Bile Salt-Stimulated Lipase and Pancreatic Lipase-Related Protein 2 Are the Dominating Lipases in Neonatal Fat Digestion in Mice and Rats.
  • 2007
  • Ingår i: Pediatr Res. - 0031-3998.
  • Tidskriftsartikel (refereegranskat)abstract
    • During infancy, the basic conditions for digestion of dietary fat differ from later in life. The bile salt-stimulated lipase (BSSL) is an enzyme expressed in the exocrine pancreas and in some species (including human) also in the lactating mammary gland and secreted with the milk. The aim of this study was to compare the ontogeny of four pancreatic lipases [BSSL, pancreatic triglyceride lipase (PL), pancreatic lipase-related protein 2 (PLRP2), and phospholipase A2 (PLA2)] in one species that supplies BSSL with milk (the mouse) and one that does not (the rat). We followed expression of the four pancreatic lipases from postnatal d 1 until after weaning in both species. We found that BSSL and PLRP2, two lipases with broad substrate specificity, dominated. It was not until weaning that significant expression of PL and PLA2 were induced. Thus, BSSL and PLRP2 seem to be responsible for fat digestion as long as milk is the main food. Moreover, the early temporal pattern of BSSL expression differed between species. We speculate that the milk-borne BSSL is able to compensate for a slower ontogeny of pancreatic BSSL expression in the mouse.PMID: 17805199 [PubMed - as supplied by publisher]
  •  
12.
  • Mathisen, Peter, et al. (författare)
  • Francisella tularensis subspecies holarctica´s adaptation to protozoan and mammal hosts
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • The long co-existence of bacteria and protozoa in natural ecosystems has led to the evolution of different bacterial predation-resistance mechanisms1, which in turn may have triggered development of mammal pathogens2, such as the tularemia bacterium Francisella tularensis3. We studied links between environmental persistence and pathogenicity of Francisella tularensis subsp. holarctica (F. t. holarctica), by comparing its growth in association with an aquatic amoeba and a murine macrophage. A virulent wild-type strain and four isogenic mutations with different functional protein deletions were compared; DsbA4, 5 a membrane lipoprotein with disulfide oxidoreductase activity important for proper folding in Francisella tularensis; Hfq6 a pleiotropic regulatory RNA binding protein; PilA7, 8 a type IV pilus subunit and PglA9 a protein involved in O-linked protein glycosylation. DsbA was found to be essential for bacterial growth in association with both amoeba and macrophage, while PglA did not affect bacterial persistence in any of the hosts. Absence of PilA and Hfq had marked negative effect on the bacterial cell counts in amoeba, while growth was only slightly impaired in the macrophage. Functional similarities for bacterial persistence in both hosts highlight eco-evolutionary links between persistence of intracellular pathogenic bacteria in aquatic systems and mammal hosts.
  •  
13.
  • Noppa, Laila, et al. (författare)
  • P13, an integral membrane protein of Borrelia burgdorferi, is C-terminally processed and contains surface-exposed domains
  • 2001
  • Ingår i: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 69:5, s. 3323-3334
  • Tidskriftsartikel (refereegranskat)abstract
    • To elucidate antigens present on the bacterial surface of Borrelia burgdorferi sensu lato that may be involved in pathogenesis, we characterized a protein, P13, with an apparent molecular mass of 13 kDa. The protein was immunogenic and was expressed in large amounts during in vitro cultivation compared to other known antigens. An immunofluorescence assay, immunoelectron microscopy, and protease sensitivity assays indicated that P13 is surface exposed. The deduced sequence of the P13 peptide revealed a possible signal peptidase type I cleavage site, and computer analysis predicted that P13 is an integral membrane protein with three transmembrane-spanning domains. Mass spectrometry, in vitro translation, and N- and C-terminal amino acid sequencing analyses indicated that P13 was posttranslationally processed at both ends and modified by an unknown mechanism. Furthermore, p13 belongs to a gene family with five additional members in B. burgdorferi sensu stricto. The p13 gene is located on the linear chromosome of the bacterium, in contrast to five paralogous genes, which are located on extrachromosomal plasmids. The size of the p13 transcript was consistent with a monocistronic transcript. This new gene family may be involved in functions that are specific for this spirochete and its pathogenesis.
  •  
14.
  •  
15.
  •  
16.
  •  
17.
  • Rydén, Patrik, 1969-, et al. (författare)
  • Evaluation of microarray data normalization procedures using spike-in experiments
  • 2006
  • Ingår i: BMC Bioinformatics. - London : BioMed Central Ltd. - 1471-2105. ; 7:300, s. 17-
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Recently, a large number of methods for the analysis of microarray data have been proposed but there are few comparisons of their relative performances. By using so-called spike-in experiments, it is possible to characterize the analyzed data and thereby enable comparisons of different analysis methods. Results: A spike-in experiment using eight in-house produced arrays was used to evaluate established and novel methods for filtration, background adjustment, scanning, channel adjustment, and censoring. The S-plus package EDMA, a stand-alone tool providing characterization of analyzed cDNA-microarray data obtained from spike-in experiments, was developed and used to evaluate 252 normalization methods. For all analyses, the sensitivities at low false positive rates were observed together with estimates of the overall bias and the standard deviation. In general, there was a trade-off between the ability of the analyses to identify differentially expressed genes (i.e. the analyses' sensitivities) and their ability to provide unbiased estimators of the desired ratios. Virtually all analysis underestimated the magnitude of the regulations; often less than 50% of the true regulations were observed. Moreover, the bias depended on the underlying mRNA-concentration; low concentration resulted in high bias. Many of the analyses had relatively low sensitivities, but analyses that used either the constrained model (i.e. a procedure that combines data from several scans) or partial filtration (a novel method for treating data from so-called not-found spots) had with few exceptions high sensitivities. These methods gave considerable higher sensitivities than some commonly used analysis methods. Conclusion: The use of spike-in experiments is a powerful approach for evaluating microarray preprocessing procedures. Analyzed data are characterized by properties of the observed log-ratios and the analysis' ability to detect differentially expressed genes. If bias is not a major problem; we recommend the use of either the CM-procedure or partial filtration.  
  •  
18.
  •  
19.
  • Salomonsson, Emelie, et al. (författare)
  • Reintroduction of two deleted virulence loci restores full virulence to the live vaccine strain of Francisella tularensis
  • 2009
  • Ingår i: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 77:8, s. 3424-3431
  • Tidskriftsartikel (refereegranskat)abstract
    • A disadvantage of several old vaccines is that the genetic events resulting in the attenuation are often largely unknown and reversion to virulence cannot be excluded. In the 1950s, a live vaccine strain, LVS, was developed from a type B strain of Francisella tularensis, the causative agent of tularemia. LVS, which is highly attenuated for humans but still virulent for mice by some infection routes, has been extensively studied and found to protect staff from laboratory-acquired tularemia. The efforts to improve biopreparedness have identified a demand for a vaccine against tularemia. Recently the rapid progress in genomics of different Francisella strains has led to identification of several regions of differences (RDs). Two genes carried within RDs, pilA, encoding a putative type IV pilin, and FTT0918, encoding an outer membrane protein, have been linked to virulence. Interestingly, LVS has lost these two genes via direct repeat-mediated deletions. Here we show that reintroduction of the two deleted regions restores virulence of LVS in a mouse infection model to a level indistinguishable from that of virulent type B strains. The identification of the two attenuating deletion events could facilitate the licensing of LVS for use in humans.
  •  
20.
  • Salomonsson, Emelie, et al. (författare)
  • Role of type IV pilin encoding genes in virulence of Francisella tularensis subspecies holarctica
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • The number of virulence factors identified in Francisella tularensis, the causative agent of tularemia, is so far relatively few. The F. tularensis genome contains some genes with homology to known virulence factors. One of these is the type IV pili system, which is known to have a key role in virulence of other bacterial species. When we compared different F. tularensis subspecies we could identify distinct differences in Type IV pilin genes between the highly virulent type A strains and the less pathogenic type B strains. In this work we addressed the role in virulence of the different pilin genes in a virulent type B strain. Of all the pilin genes only PilA and the pseudopilins FTT1621-1622 were proven to have a role in virulence. In addition we also verified that the gene encoding the PilT ATPase is non-functional due to a non-sense mutation and we also confirmed that the truncated pilT has no role in mouse virulence. Furthermore we also provide evidence that the F. tularensis pilins are posttranslationally modified presumably by glycosylation by a PilO dependent mechanism.
  •  
21.
  • Sidstedt, Maja, et al. (författare)
  • Humic substances cause fluorescence inhibition in real-time PCR.
  • 2015
  • Ingår i: Analytical Biochemistry. - : Elsevier BV. - 1096-0309 .- 0003-2697. ; 487, s. 30-37
  • Tidskriftsartikel (refereegranskat)abstract
    • Real-time PCR (qPCR) is the cornerstone of DNA analysis, enabling detection and quantification of minute nucleic acid amounts. However, PCR-based analysis is limited, in part, by the presence of inhibitors in the samples. PCR inhibition has been viewed solely as failure to efficiently generate amplicons, i.e. amplification inhibition. Humic substances (HS) are well known inhibitors of PCR amplification. Here we show that HS from environmental samples, specifically humic acid (HA), are very potent detection inhibitors, i.e. quench the fluorescence signal of dsDNA binding dyes. HA quenched the fluorescence of the commonly used qPCR dyes EvaGreen, ResoLight, SYBR Green I and SYTO 82, generating lowered amplification plots although amplicon production was unaffected. For EvaGreen, 500 ng HA quenched almost all fluorescence, whereas 1000 ng HA completely inhibited amplification when applying Immolase DNA polymerase with BSA. Fluorescence spectroscopy measurements showed that HA quenching was either static or collisional, and indicated that HA bound directly to the dye. Fulvic acid did not act as a qPCR detection inhibitor, but inhibited amplification similarly to HA. Hydrolysis probe fluorescence was not quenched by HA. Detection inhibition is an overlooked phenomenon that needs to be considered to allow for development of optimal qPCR assays.
  •  
22.
  • Straskova, Adela, et al. (författare)
  • Proteome analysis of an attenuated Francisella tularensis dsbA mutant : identification of potential DsbA substrate proteins
  • 2009
  • Ingår i: Journal of Proteome Research. - : American Chemical Society (ACS). - 1535-3893 .- 1535-3907. ; 8:11, s. 5336-5346
  • Tidskriftsartikel (refereegranskat)abstract
    • Francisella tularensis (F. tularensis) is highly infectious for humans via aerosol route and untreated infections with the highly virulent subsp. tularensis can be fatal. Our knowledge regarding key virulence determinants has increased recently but is still somewhat limited. Surface proteins are potential virulence factors and therapeutic targets, and in this study, we decided to target three genes encoding putative membrane lipoproteins in F. tularensis LVS. One of the genes encoded a protein with high homology to the protein family of disulfide oxidoreductases DsbA. The two other genes encoded proteins with homology to the VacJ, a virulence determinant of Shigella flexneri. The gene encoding the DsbA homologue was verified to be required for survival and replication in macrophages and importantly also for in vivo virulence in the mouse infection model for tularemia. Using a combination of classical and shotgun proteome analyses, we were able to identify several proteins that accumulated in fractions enriched for membrane-associated proteins in the dsbA mutant. These proteins are substrate candidates for the DsbA disulfide oxidoreductase as well as being responsible for the virulence attenuation of the dsbA mutant.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-22 av 22
Typ av publikation
tidskriftsartikel (14)
annan publikation (6)
konferensbidrag (1)
bokkapitel (1)
Typ av innehåll
refereegranskat (15)
populärvet., debatt m.m. (4)
övrigt vetenskapligt/konstnärligt (3)
Författare/redaktör
Noppa, Laila (22)
Bergström, Sven (7)
Kuoppa, Kerstin (7)
Sjöstedt, Anders (6)
Olsen, Björn (5)
Salomonsson, Emelie (5)
visa fler...
Forsberg, Åke, 1951- (5)
Andersson, Henrik (4)
Näslund, Linda (4)
Östberg, Yngve (4)
Forsman, Mats (3)
Forsberg, Åke (3)
Rydén, Patrik (3)
Hartmanová, Blanka (3)
Landfors, Mattias (3)
Forslund, Anna-Lena (3)
Jaenson, Thomas G T (3)
Titball, Richard (3)
Weihe, Pál (2)
Golovliov, Igor, 195 ... (2)
Gylfe, Åsa (2)
Sjöstedt, Anders, 19 ... (2)
Johansson, Anders (1)
Andersson, Agneta (1)
Hernell, Olle (1)
Svensson, Kerstin (1)
Mathisen, Peter (1)
Nilsson, Elin (1)
Thelaus, Johanna (1)
Berglund, Johan (1)
Hedman, Johannes (1)
Lindquist, Susanne (1)
Hartmanova (Andersso ... (1)
Näslund, A. (1)
Rådström, Peter (1)
Stulik, Jiri (1)
Ornstein, Katharina (1)
Mejlon, H (1)
Zingmark, Carl, 1975 ... (1)
Sidstedt, Maja (1)
Jansson, Linda (1)
Byström, Mona (1)
Titball, Richard W. (1)
Bunikis, J (1)
Bunikis, Jonas (1)
Straskova, Adela (1)
Michell, Stephen L (1)
Li, Xiaonan (1)
Oyston, Petra C. F. (1)
Golovliov, Igor (1)
visa färre...
Lärosäte
Umeå universitet (17)
Linnéuniversitetet (4)
Lunds universitet (2)
Språk
Engelska (22)
Forskningsämne (UKÄ/SCB)
Naturvetenskap (7)
Medicin och hälsovetenskap (7)

År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy