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| 2. |
- Dixelius, Johan, 1958-
(author)
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Endothelial differentiation and angiogenesis regulation
- 2002
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Doctoral thesis (other academic/artistic)abstract
- Angiogenesis can be defined as the formation of new blood vessels from pre-existing ones. Angiogenesis is required for development and maintenance of our vascular system and thus of fundamental importance to our existence. The endothelial cells that line the inside of the vessels de-differentiate, migrate, proliferate and re-differentiate during angiogenesis. Angiogenesis is tightly regulated, controlled by several angiogenic factors of various classes that promote angiogenesis but also by anti-angiogenic factors that counteract the effect of the pro-angiogenic factors. We have examined three factors involved in angiogenesis regulation, Vascular endotelial growth factor (VEGFR) -3, the matrix protein laminin-1 and the collagen XVIII derived fragment endostatin. Five tyrosine phosphorylation sites in the cytoplasmic tail of VEGFR-3 were identified by phosphopeptide mapping (PPM). The data was confirmed by PPM using point-mutated receptors generated by site-directed mutagenesis.Laminin-1 was found to promote angiogenesis in the chicken chorioallantoic membrane assay and in a synergistic fashion together with suboptimal levels of fibroblast growth factor 2 (FGF-2) in embryoid bodies. Laminin-1 also promoted endothelial tubular morphogenesis in vitro, and upregulated the expression of the endothelial differentiation marker Jagged-1. Endostatin was shown to affect endothelial FGF-2-induced cell survival and morphogenesis. This was a result of direct binding to endothelial cells and induction of tyrosine phosphorylation of many proteins including the adaptor protein Shb. The apoptotic and morphogenic responses induced by endostatin was shown to be dependent on Shb. Further, endostatin inhibited endothelial migration and affected molecules implicated in migration. In particular, FGF-2 induced actin reorganization, and β-catenin regulation was modulated by endostatin.
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| 3. |
- Lindh, Roland, 1958-, et al.
(author)
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Low-rank configuration interaction with orbital optimization - the LR SCF approach
- 1988
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In: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 148:4, s. 276-280
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Journal article (peer-reviewed)abstract
- Orbital optimization has been included in the low-range (LR) CI approach to configuration interaction, It is shown to have a noticeable effect on the computed correlation energy when only a small number of single excitation operators are used to approximate the doubly excited part of the wavefunction. The importance of optimization decreases rapidly when the number of parameters describing the LR wavefunction is increased. Test calculations are performed for H2O (geometry optimization) and for the polarizability of F−. Optimization of the orbitals leads to improved convergence for all properties studied.
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| 4. |
- Olofsson, Jenny, 1980-, et al.
(author)
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The Abundant Free Living Amoeba, Acanthamoeba polyphaga, Increases the Survival of Campylobacter jejuni in Milk and Orange Juice
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Other publication (other academic/artistic)abstract
- Campylobacter jejuni is a common cause of human bacterial diarrhea in most parts of the world. Most C. jejuni infections are acquired from contaminated poultry, milk and water. Due to health care costs and human suffering, it is important to identify all possible sources of infection. Unpasteurized milk has been associated with several outbreaks of C. jejuni infection. Campylobacter has been identified on fresh fruit and other gastrointestinal pathogens such as Salmonella, E. coli O157:H7 and Cryptosporidium have been involved in fruit juice outbreaks. C. jejuni is sensitive to the acidic environment of fruit juice, but co-cultures with A. polyphaga have previously been shown to protect C. jejuni at low pH. In this study we found that co-culture with A. polyphaga prolonged the C. jejuni survival both in milk and juice. The effect of co-culture was most pronounced in juice stored at room temperature. On the other hand, we found that A. polyphaga did not have any effect on C. jejuni survival during pasteurization of milk or orange juice, indicating that this is a good method for eliminating C. jejuni in these products. In conclusion, amoebae associated C. jejuni in milk and juice might cause C. jejuni infections.
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| 5. |
- Olsen, Björn, 1958-
(author)
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Birds and Borrelia
- 1995
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Doctoral thesis (other academic/artistic)abstract
- The Lyme disease causing spirochaete Borrelia burgdorferi sensu lato is transmitted by ticks within the genus Ixodes. These ticks are liberal host seekers and parasitise mammals, birds and reptiles.Prior to this study, the distribution of I. ricinus ticks and Lyme disease was thought to be restricted to the southern half of Sweden. On the island Norrbyskär, located in the Bothnian Gulf, there were reports of a high incidence of tick infestation on humans. To investigate the occurrence of B. burgdorferi s.l. in these ticks and to characterise presumptive isolates at the molecular level we sampled a number of I. ricinus ticks. Three different isolates were obtained from two different ticks, NBS16 from a nymph and NBS23a and NBS23b from an adult female tick.The seabird associated tick I. uriae is circumpolar distributed in both hemispheres. On the island Bonden, which house one of the largest seabird colonies in the Baltic Sea, I. uriae were collected and surveyed for spirochaetes. One isolate of B. burgdorferi s.l. was obtained. This B. burgdorferi s.l. isolate is identical to the Lyme disease Borrelia strain NBS16 isolated from Norrbyskär.To investigate the role of seabirds in the epidemiology of B. burgdorferi s.l., I. uriae were collected from seabird colonies in the southern and northern hemispheres. Borrelia DNA was extracted from the ticks and from cultured spirochaetes. Sequence analysis of the flagellin gene revealed that the DNA obtained was from B. garinii, regardless of the geographical origin of the sample. Identical fla gene fragments in ticks collected in both hemispheres indicate a transhemispheric exchange of B. garinii. A marine ecological niche and epidemiological route for Lyme disease Borrelia are proposed.The prevalence of B. burgdorferi s.l. infected ticks on migrating passerine birds was studied. A total of 22, 998 birds were caught and examined for ticks. The presence of spirochaetes in the 967 collected ticks was determined by DNA amplification by PCR on all ticks. To determine which B. burgdorferi s.l. species were present, classification was performed by DNA amplification using species-specific 16S rDNA primers and by DNA sequencing. Flagellin gene sequences of all species of B. burgdorferi s.l. previously recorded in Europe were found. B. garinii was the most prevalent. These data support the notion that passerine birds are at least partly responsible for the distribution of Lyme disease Borrelia spirochaetes in Europe.To elucidate the distribution of B. burgdorferi s.l. in subarctic regions, strains isolated from I. ricinus and I. uriae ticks found on islands in the northern Atlantic and Baltic Sea were characterised molecularly. All isolates were verified as B. garinii by 16S-rRNA gene analysis and immunoblotting using monoclonal antibodies specific for the outer surface proteins A and C. Three ribotypes (RT's) of B. garinii were found. The I. ricinus associated RT1 is phenotypically the most heterogeneous. RT2 is restricted to the islands in the northern Baltic Sea, whereas RT3 was also recovered from ticks found on islands in the North Atlantic. The heterogeneity of the B. garinii population in the Baltic Sea might be influenced by two geographically opposite directions, North Atlantic (RT3) and Euroasia (RT1).
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| 6. |
- Olsen, Jeppe, et al.
(author)
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A non-linear approach to configuration interaction: The low-rank CI method (LR CI)
- 1987
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In: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 133:2, s. 91-101
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Journal article (peer-reviewed)abstract
- An alternative to the linear CI expansion is presented, which is based on the spectral resolution of the double excitation CI coefficients arranged as a symmetric matrix. The resulting energy expression is a quartic function of the new variables, where the double excitation operator is given as T̂2 = ∑IMωI(d̂I)2, where d̂dI is a single excitation operator: d̂I =∑Ia,d̂IiaÊai. Since M is a small number, the number of variables is reduced considerably compared to normal SDCI, with only little loss in accuracy. A program for non-linear CI calculations has been written and is presented with results for H2O and N2. The method can easily be extended to include orbital optimization and cluster terms in the wavefunction, still yielding a fully variational approximation to the Schrödinger equation.
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| 7. |
- Palmgren, Helena, 1955-, et al.
(author)
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Enteropathogenic Bacteria in Migrating Birds Arriving in Sweden
- 1997
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In: Scandinavian Journal of Infectious Diseases. - : Scandinavian University Press. - 0036-5548 .- 1651-1980. ; 29:6, s. 565-568
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Journal article (peer-reviewed)abstract
- Birds have been thought to play a role in transmitting infectious agents like influenza, Borrelia and Salmonella. To investigate the role of migrating birds in the dispersal of enteropathogenic bacteria, stool samples from 151 wild birds (50 gulls and 101 passerines) just entering Sweden from their winter grounds were analysed for Salmonella spp., Campylobacter spp. and EHEC O157:H7. The thermophilic isolated enteropathogens found were further analysed by antibiograms. Among the 50 gulls examined, we found 2 isolates of Salmonella typhimurium with multiple antibiotic resistance. Three isolates of C. jejuni were found in the 101 stool samples from passerines. We did not isolate EHEC O157:H7 in any of the bird stools examined.
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| 8. |
- Palmgren, Helena, 1955-, et al.
(author)
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Salmonella Aamager, Campylobacter jejuni, and urease-positive thermophilic Campylobacter found in free-flying peregrine falcons (Falco peregrinus) in Sweden
- 2004
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In: Journal of Wildlife Diseases. - : Wildlife Disease Association. - 0090-3558 .- 1943-3700. ; 40:3, s. 583-587
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Journal article (peer-reviewed)abstract
- Rare species with small population sizes are vulnerable to perturbations such as disease, inbreeding, or random events. The threat arising from microbial pathogens could be large and other species could act as reservoirs for pathogens. We report finding three enteric bacterial species, Salmonella Amager, Campylobacter jejuni, and urease-positive thermophilic Campylobacter, in nestling free-flying peregrine falcons (Falco peregrinus) in Sweden in 2000. Cainpylobacterfied inarked genetic similarities to an isolate froin a human, providing a possible association between a human-associated strain of this bacterinin and peregrine falcons.
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| 9. |
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| 10. |
- Palmgren, Helena, 1955-, et al.
(author)
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Salmonella in sub-Antarctica : low heterogeneity in salmonella serotypes in South Georgian seals and birds
- 2000
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In: Epidemiology and Infection. - : Cambridge University Press. - 0950-2688 .- 1469-4409. ; 125:2, s. 257-262
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Journal article (peer-reviewed)abstract
- The number of human visitors to Antarctica is increasing rapidly, and with it a risk of introducing infectious organisms to native animals. To study the occurrence of salmonella serotypes in sub- Antarctic wildlife, faecal samples were collected from gentoo penguins, macaroni penguins, gray-headed albatrosses, black-browed albatrosses and Antarctic fur seals on Bird Island in the South Georgian archipelago during the austral summer of 1996 and 1998. In 1996, S. havana, S. typhimurium and S. enteritidis were isolated from 7% of gentoo penguins and 4% of fur seals. In 1998, however, 22% of fur seals were found to be infected with S. havana, S. enteritidis and S. newport. All isolates, except one, showed identical pulsed-field gel electrophoresis-patterns within each serotype, irrespective of sampling year and animal reservoir. No significant antibiotic resistance was found. The very low heterogeneity in the salmonella isolates found could either indicate a high genetic adaptation of the bacteria to the environment or a recent introduction of salmonella into the area.
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