| 1. |
- Tinnsten, Mats, et al.
(författare)
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Optimization of acoustic response
- 1999
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Ingår i: Structural Optimization. - 0934-4373. ; 18:1, s. 36-47
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Tidskriftsartikel (refereegranskat)abstract
- The expression 'acoustic optimization' can be applied to numerous different disciplines within the field of acoustics. From seismic waves, sound in the atmosphere through bioacoustic, psychoacoustics, and room and theater acoustics over shock and vibration in mechanical structures. This paper deals with the latter. Sound generated by vibrating structures is often called noise which is to be minimized. However, not all vibrating structures produce noise, for example the violin is also a vibrating structure that in most people's opinion produces sound called music. In the case of the violin, great effort is made not to minimize but to optimize the sound, i.e. to get the 'right' sound out of the structure. Acoustic optimization within this discipline involves automatic changes of structural design variables to obtain minimum or specified sound in specified regions inside or outside the structure. Examples of problem formulations and some theoretical considerations in the field of acoustic optimization in connection with vibrating mechanical structures will be pointed out. Four simple test cases are included as numerical examples of the method proposed.
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| 2. |
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| 3. |
- Bergström, Sven, et al.
(författare)
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Molecular characterization of Borrelia burgdorferi isolated from Ixodes ricinus in northern Sweden.
- 1992
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 24:2, s. 181-188
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Tidskriftsartikel (refereegranskat)abstract
- Ixodes ricinus ticks, harbouring Borrelia burgdorferi, were found in an area in northern Sweden, not thought to be endemic for Lyme borreliosis. This investigation took place at Norrbyskär, an island situated in the Bothnian Gulf, 63 degrees 33'N/19 degrees 52'E. One of 42 nymphal and 8/43 adult I. ricinus ticks collected carried spirochetes as seen by phase contrast microscopy. Pure bacterial cultures were obtained from 2 of the ticks. Western blot analysis using species-specific monoclonal antibodies showed that the isolated spirochetes were B. burgdorferi. The identity of the isolated spirochetes was confirmed by DNA amplification using B. burgdorferi OspA and flagellin gene specific oligonucleotides as well as partial DNA sequencing of the respective OspA and flagellin genes. The 2 isolated spirochaete populations were different as shown by their protein profiles in sodium dodecyl sulphate polyacrylamide gels. Moreover, the demonstration of Lyme borreliosis in a patient from the island of Norrbyskär indicates the need for clinical consideration of this disease in northern Sweden.
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| 4. |
- Björkvall, Gunilla, Iversen, Gunilla, et al.
(författare)
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"A brief Description of Corpus Troporum"
- 1992
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Ingår i: Proceedings of the first British– Swedish conference on musicology, Medieval studies. - : Stockholm. ; , s. 119-122.
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 5. |
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| 6. |
- Jonsson, Maria, 1966-
(författare)
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Contribution of the outer surface proteins of Borrelia burgdorferi s.l. to the pathogenesis of Lyme disease
- 1994
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Borrelia burgdorferi s. l. is a spirochete which causes the multisystemic disorder Lyme disease. As the borreliae lack toxin production, the pathogenicity is thought to involve, at least in part, molecules from the outer surface. Most Lyme disease Borrelia strains express two major outer surface lipoproteins, OspA (31 kD) and OspB (34 kD), on their surface. However, some strains lack the expression of OspA and OspB, but express a smaller 21 to 25 kD OspC protein instead. This thesis focuses on the importance of these proteins in the pathogenesis of Lyme disease.Biochemical and immunochemical studies of the OspA and OspB proteins from strains of various geographic origins show considerable differences in the apparent molecular weights and in their reactivities to monoclonal antibodies. The cloning and sequencing of the ospAB opérons from strains of different origins has demonstrated that the heterogeneity is found also at the DNA level Comparison of the ospAB sequences allows the classification of the strains into three types, which coincide with the recent species designations, B. burgdorferi sensu stricto, B. afzelii and B. garinii The genes are located on a linear plasmid about 50 kb in size, and are cotranscribed as a single message.The expression of the osp operon in different strains was studied by Western blot and Northern blot analysis. The ospAB operon of strains expressing varying amounts of the Osp proteins was cloned and sequenced. The DNA sequence was found to be >99% identical. The regulation appears to be primarily at the transcriptional level.In patients who have received incomplete treatment, B. burgdorferi have been isolated several years after the onset of the disease. As mentioned above, the ospAB loci of different strains show considerable heterogeneity, and it has been speculated that the spirochetes evade the host’s immune system by antigenic variation of the Osp proteins. In a mouse model system it was shown that no variation of the osp genes occurs over the course of an infection, and that other escape mechanisms must be used.The OspB proteins in particular have been shown to be very heterogeneous in different isolates. The MAb 84C recognizes a wide variety of B. burgdorferi strains, and the binding epitope was mapped to a conserved region in the carboxyl terminus of the OspB protein with putative structural and/or functional importance.It is well known that antibodies can kill bacteria in the presence of complement and phagocytes. Some antibodies seem to have a bactericidal effect by themselves. H6831 is a monoclonal antibody recognizing the OspB protein of some B. burgdorferi strains. The bactericidal action of univalent FAb fragments from H6831 was further characterized, and the binding epitope was mapped to a very heterogeneous region of the carboxyl end of the OspB protein.
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| 7. |
- Jonsson, Maria, et al.
(författare)
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Heterogeneity of outer membrane proteins in Borrelia burgdorferi : comparison of osp operons of three isolates of different geographic origins.
- 1992
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Ingår i: Infection and Immunity. - : American Society for Microbiology. - 0019-9567 .- 1098-5522. ; 60:5, s. 1845-53
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Tidskriftsartikel (refereegranskat)abstract
- Biochemical and immunochemical studies of the outer membrane proteins of Borrelia burgdorferi have shown that the OspA and OspB proteins from strains of different geographic origins may differ considerably in their reactivities with monoclonal antibodies and in their apparent molecular weights. To further characterize this variation in Osp proteins between strains, the osp operons and deduced translation products from two strains, one from Sweden (ACAI) and one from eastern Russia (Ip90), were studied. Polyacrylamide gel electrophoresis and Western blot (immunoblot) analyses confirmed differences between ACAI, Ip90, and the North American strain B31 in their Osp proteins. The sequences of the ospA and ospB genes of ACAI and Ip90 were compared with that of the previously studied osp operon of B31 (S. Bergström, V. G. Bundoc, and A. G. Barbour, Mol. Microbiol. 3:479-486, 1989). The osp genes of ACAI and Ip90, like the corresponding genes of B31, were found on plasmids with apparent sizes of about 50 kb and are cotranscribed as a single unit. Pairwise comparisons of the nucleotide sequences revealed that the ospA genes of ACAI and Ip90 were 85 and 86% identical, respectively, to the ospA gene of strain B31 and 86% identical to each other. The ospB sequences of these two strains were 79% identical to the ospB gene of B31 and 81% identical to each other. There was significantly greater similarity between the ospA genes of the three different strains than there was between the ospA and ospB genes within each strain. These studies suggest that the duplication of osp genes in B. burgdorferi occurred before the geographical dispersion of strains represented by ACAI, Ip90, and B31.
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| 8. |
- Jonsson, Maria, et al.
(författare)
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Subcutaneous implanted chambers in different mouse strains as an animal model to study genetic stability during infection with Lyme disease Borrelia
- 1995
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Ingår i: Microbial Pathogenesis. - : Academic Press. - 0882-4010 .- 1096-1208. ; 18:2, s. 109-14
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Tidskriftsartikel (refereegranskat)abstract
- Tissue metal net cages were implanted subcutaneously in BALB/cJ and C3H/Tif mice as an experimental model of Borrelia burgdorferi infection. B. burgdorferi sensu stricto strain Sh2-82 could be isolated up to 14 weeks after the inoculation. However, a significant difference in infectivity between the two mice strains was observed. C3H/Tif mice were more susceptible to developing chronic B. burgdorferi s.s. infections than BALB/cJ mice. Although a B. burgdorferi infection was established, no rearrangements in the ospA and ospB genes were observed in any of the infected mice.
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| 9. |
- Jonsson, Maria, et al.
(författare)
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Transcriptional and translational regulation of the expression of the major outer surface proteins in Lyme disease Borrelia strains
- 1995
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Ingår i: Microbiology. - : Society for General Microbiology. - 1350-0872 .- 1465-2080. ; 141:6, s. 1321-1329
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Tidskriftsartikel (refereegranskat)abstract
- The major outer surface proteins of Lyme disease spirochaetes are differentially expressed in different isolates. Borrelia afzelii strain F1 expresses none, or very low amounts, of the OspA and OspB proteins. To elucidate the mechanisms that control the expression of these abundant surface proteins the ospAB operon of B. afzelii F1 was cloned, sequenced and compared to the previously sequenced ospAB operon of B. afzelii ACAI and Borrelia burgdorferi B31. The two B. afzelii strains showed almost 100% identity at the DNA level, although Coomassie-stained gels and Western blot analyses showed significant variation in the Osp protein content. Transcriptional analysis revealed that the amount of ospAB mRNA produced in B. afzelii F1 varies more than the amount of protein, suggesting that the expression of OspA and OspB proteins is regulated at both the transcriptional and the translational level. Furthermore, the inverse relationship between the transcription of ospC and the ospAB operon could indicate coregulation of these separately encoded operons.
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| 10. |
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