| 1. |
- Johansson, Eva-Liz, et al.
(författare)
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Comparison of different routes of vaccination for eliciting antibody responses in the human stomach
- 2004
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Ingår i: Vaccine. - : Elsevier BV. - 0264-410X. ; 22:8, s. 984-90
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Tidskriftsartikel (refereegranskat)abstract
- Determination of optimal routes to induce mucosal immune responses locally in the stomach and duodenum are important steps in the development of vaccines against Helicobacter pylori infection. In this study, we immunized H. pylori-infected individuals either nasally or rectally with a model antigen, i.e. cholera toxin B subunit, and compared the immune responses after these routes with the responses after oral or intrajejunal vaccination. Specific antibody levels in serum as well as specific antibody levels and antibody-secreting cells in biopsies from antrum and duodenum were determined by ELISA and ELISPOT methods. In contrast to oral vaccination, nasal and rectal vaccination did not induce significant increases in specific antibody-secreting cells either in the antrum or duodenum. Furthermore, when analyzing the antibody levels in saponin extracted biopsies, intrajejunal vaccination was superior to both nasal and rectal vaccination in inducing antigen-specific IgA levels in the stomach. We conclude that oral vaccination is the optimal route for induction of antigen-specific IgA antibody responses in the stomach and duodenum of humans, while nasal or rectal vaccination is less suitable for this purpose.
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| 2. |
- Johansson, Anders, 1966-
(författare)
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A genome-wide DNA microarray analysis of Francisella tularensis strains demonstrates extensive genetic conservation within the species but identifies regions that are unique to the highly virulent F. tularensis subspecies tularensis.
- 2002
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Francisella tularensis is a potent pathogen and a possible bioterrorism agent. Little is known, however, to explain the molecular basis for its virulence and the distinct differences in virulence found between the four recognized subspecies tularensis, mediaasiatica, holarctica, and novicida. We developed a DNA microarray based on 1,832 clones from a shotgun library used for sequencing of the highly virulent F. tularensis subspecies tularensis, strain Schu S4. This allowed a genome-wide analysis of 27 strains representing all four subspecies. Overall, the microarray analysis confirmed a limited genetic variation within the species F. tularensis, and when strains were compared, at most 3.7 % of the probes showed differential hybridization. Despite marked differences in their virulence and geographical origin, a high genomic similarity between strains of the subspecies tularensis and mediaasiatica was apparent. Within the subspecies holarctica, strains from Japan showed unique hybridization patterns. Eight Regions of Difference (RD), 0.6 - 11.5 kb in size altogether comprising 21 open reading frames, were identified that distinguished strains of the moderately virulent subspecies holarctica and the highly virulent subspecies tularensis, respectively. One of these regions, RD1, allowed for the first time the development of a F. tularensis specific PCR assay discriminating each of the four subspecies.
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| 3. |
- Johansson, Anders, 1966-
(författare)
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Comparative analysis of PCR versus culture for diagnosis of ulceroglandular tularemia
- 2000
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Ingår i: Journal of Clinical Microbiology. - Washington D.C. : ASM. - 0095-1137 .- 1098-660X. ; 38:1, s. 22-26
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Tidskriftsartikel (refereegranskat)abstract
- PCR and culture were comparatively evaluated for their abilities to demonstrate Francisella tularensis in wound specimens from tularemia patients during an outbreak in Sweden in 1998. For transport of the specimens used for PCR, a buffer solution containing a nuclease inhibitor was used, and for transport of the specimens used for culture, a commercial transport system was selected after experimental comparison of various systems. Of 40 patients with culture- and/or serology-verified ulceroglandular tularemia, PCR detected F. tularensis DNA in 30 (75%) patients, whereas culture detected bacterial growth in 25 (62%) patients. Compared to data from a previous study, the present inclusion of a nuclease inhibitor in the transport medium did not improve the sensitivity of the PCR, whereas the sensitivity of the culture procedure was significantly increased by selection of the system used for transport. Among eight patients with clinically suspected tularemia but with negative serology and culture, specimens from four patients showed detectable DNA. In three of these patients the diagnosis was verified by the demonstration of an F. tularensis-specific T-cell response in vitro. In conclusion, PCR was more sensitive than culture for demonstration of F. tularensis in wound specimens. Besides, we showed that tularemia may proceed without development of serum antibodies, and in these patients, PCR may be of special importance for verification of the diagnosis.
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| 4. |
- Johansson, Anders, 1966-
(författare)
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Evaluation of PCR-based methods for discrimination of Francisella species and subspecies and development of a specific PCR that distinguishes the two major subspecies of Francisella tularensis.
- 2000
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Ingår i: Journal of Clinical Microbiology. - Washington D.C. : ASM. - 0095-1137 .- 1098-660X. ; 38:11, s. 4180-4185
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies have demonstrated that the four subspecies of the human pathogen Francisella tularensis, despite showing marked variations in their virulence for mammals and originating from different regions in the Northern Hemisphere, display a very close phylogenetic relationship. This property has hampered the development of generally applicable typing methods. To overcome this problem, we evaluated the use of PCR for discrimination of the subspecies using various forms of long arbitrary primers or primers specific for repetitive extragenic palindromic sequences (REP) or enterobacterial repetitive intragenic consensus (ERIC) sequences. Patterns generated by use of REP, ERIC, or long arbitrary primers allowed differentiation at the species level and of the four subspecies of F. tularensis. With each of these three methods, similar or identical clustering of strains was found, and groups of strains of different geographical origins or differing in virulence showed distinct patterns. The discriminatory indices of the methods varied from 0.57 to 0.65; thus, the patterns were not sufficiently discriminatory to distinguish individual strains. The sequence of a fragment generated by amplification with an arbitrary primer was determined, and a region showing interstrain heterogeneity was identified. Specific primers were designed, and a PCR was developed that distinguished strains of F. tularensis subsp. holarctica from strains of other F. tularensis subspecies, including strains of the highly virulent F. tularensis subsp. tularensis. Notably, one European isolate showed the genetic pattern typical of the highly virulent F. tularensis subsp. tularensis, generally believed to exist only in North America. It is proposed that a combination of the specific PCR together with one method generating subspecies-specific patterns is suitable as a rapid and relatively simple strategy for discrimination of Francisella species and subspecies.
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| 5. |
- Johansson, Anders, 1966-
(författare)
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Extensive allelic variation among Francisella tularensis strains in a short-sequence tandem repeat region
- 2001
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Ingår i: Journal of Clinical Microbiology. - Washington D. C. : ASM. - 0095-1137 .- 1098-660X. ; 39:9, s. 3140-3146
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Tidskriftsartikel (refereegranskat)abstract
- Members of the genus Francisella and the species F. tularensis appear to be genetically very similar despite pronounced differences in virulence and geographic localization, and currently used typing methods do not allow discrimination of individual strains. Here we show that a number of short-sequence tandem repeat (SSTR) loci are present in F. tularensis genomes and that two of these loci, SSTR9 and SSTR16, are together highly discriminatory. Labeled PCR amplification products from the loci were identified by an automated DNA sequencer for size determination, and each allelic variant was sequenced. Simpson's index of diversity was 0.97 based on an analysis of 39 nonrelated F. tularensis isolates. The locus showing the highest discrimination, SSTR9, gave an index of diversity of 0.95. Thirty-two strains isolated from humans during five outbreaks of tularemia showed much less variation. For example, 11 of 12 strains isolated in the Ljusdal area, Sweden in 1995 and 1998 had identical allelic variants. Phenotypic variants of strains and extensively cultured replicates within strains did not differ, and, for example, the same allelic combination was present in 55 isolates of the live-vaccine strain of F. tularensis and another one was present in all 13 isolates of a strain passaged in animals. The analysis of short-sequence repeats of F. tularensis strains appears to be a powerful tool for discrimination of individual strains and may be useful for a detailed analysis of the epidemiology of this potent pathogen.
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| 6. |
- Johansson, Anders, 1972-, et al.
(författare)
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Influence of tidal volume and thoraco-abdominal separation on the respiratory induced variation of the photoplethysmogram
- 2000
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Ingår i: Journal of clinical monitoring and computing. - 1387-1307 .- 1573-2614. ; 16:8, s. 575-581
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Tidskriftsartikel (refereegranskat)abstract
- Objective. The present study was aimed at determining the relative influences of tidal volume and thoraco-abdominal separation (relative thoracic and abdominal contribution to the tidal volume) on the respiratory induced intensity variation (RIIV) of the photoplethysmographic signal. The effects were studied in two body positions. Methods. Respiratory inductive plethysmography was used or quantifying thoraco-abdominal separation and for assessing tidal volumes. 10 subjects were trained to perform widely varying degrees of thoraco-abdominal separation at different tidal volumes. The relationship between the RIIV signal peak-to-peak value (measured at the forearm), and the tidal volume and thoraco-abdominal separation was investigated in two body positions with the use of multiple linear regression. Results. Larger tidal volume and more thoracic contribution to respiration were found to increase the RIIV peak-to-peak value (p < 0.0005). In the supine position, the tidal volume influence was stronger than that of thoraco-abdominal separation, and in the sitting position, the opposite was seen. Conclusions. The effects on the RIIV signal following changes in thoraco-abdominal separation and tidal volume are of the same order of magnitude. In the supine position, the influence of thoracic versus abdominal contribution to the tidal volume is not as significant as in the sitting position. Photoplethysmography is a promising technique for combined monitoring of several respiratory parameters, including tidal volume. In situations where the relative thoracic and abdominal contribution are likely to vary, the tidal volume information becomes less reliable.
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| 7. |
- Johansson, Anders, 1966-
(författare)
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The Architectural Metaphor : Textual Models in Spatial Construction
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The dissertation concerns the concept of model withinarchitecture, and elaborates particular uses in this field,where modelling is a heuristic process aiming at invention anddiscovery. Methodologically, this is made by introducing thecomparative concepts of metaphor and narrative. Thedissertation presents a‘projective theory ofmodels’, describing cases in which it is utilized both inthe production of and in applied models.A projective model has as a purpose to develop concepts andformulate structures, which otherwise would be unarticulated.Here the representative status is critical, and when treated asa material object, the reductivity of the model may bequestioned. This is explored through the correlative conceptsof metaphor and narrative. Theory of metaphor is used toexamine the nature of the transferences between the model andits reference. Narrative is used as a tool to elaborate thesetransferences, and in acquiring a certain organization of agiven space. The theoretical framework is developed bydiscussing relevant works by Nelson Goodman, regarding thetheory of representational systems and notationality, MaxBlack, regarding the relation between scientific models andmetaphor, Paul Ricoeur, regarding theory of metaphor andnarrativity, and Michel de Certeau, regarding narrativity andthe relationship between the city and textual structures.The concept of model falls into two categories,consecutively studied within the dissertation: First, models inarchitectural production. This covers all means ofrepresentation, including drawing, three dimensional models andtext, that is, everything at hand for an architect to model aconstruction during its process of becoming. Second, modelswithin built matter. This covers images and ornamentation ofsurfaces, told and written narratives about a space, andemergent social behaviour in relation to its physicalenvironment. Such use of models can be described as‘spatial tropes’, defining particular functionsperformed in space. The processes of producing and using modelsin architecture show similar characteristics. Informed by boththe theoretical elaboration and the investigations of the twocategoriesin which models are at work, a number of keyconcepts operative in the modelling process arearticulated.
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| 8. |
- Pettersson-Reif, B. Anders, 1966, et al.
(författare)
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Proper orthogonal decomposition of stratified shear turbulence
- 2004
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Ingår i: Advances in Turbulence X, Proceedings of the tenth European turbulence conference, Andersson, H.I. and Krogstad, P.- Å. (Eds.), June 29 - July 2, Trondheim, Norway.
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Konferensbidrag (refereegranskat)
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| 9. |
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