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| 2. |
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| 3. |
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| 4. |
- Sandström, Olof, et al.
(författare)
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Miljöpåverkan av skogsindustriutsläpp
- 1997
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Ingår i: Naturvårdsverkets rapportserie. Rapport 4695. ; , s. 1-89
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 5. |
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| 6. |
- Wright, Sandra A. I.
(författare)
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The genetics of antibiotic production and the role of antibiotics in biological control of Erwinia amylovora by Erwinia herbicola
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Erwinia herbicola is an epiphyte of apple and pear with potential as a biocontrol agent of Erwinia amylovora, which causes fire blight. This research aimed to assess the relative role of antibiotics produced by E. herbicola, Eh318 as a mechanistic basis for biocontrol. A genomic library of Eh318 DNA was constructed in Escherichia coli and two distinct cosmids, pCPP702 and pCPP704, were identified that conferred upon E. coli the ability to produce two antibiotics inhibitory to E. amylovora. The antibiotics were distinct based on their spectra of activity, differential susceptibility to the presence of histidine and arginine and antibiotic production by marker-exchange mutants of Eh318. Transposon mutagenesis and subcloning were used to delineate the Eh318 DNA that enabled E. coli to produce the two antibiotics. The smallest clone that conferred antibacterial activity was pCPP717. Its antibiotic was named pantocin A. The Eh318 insert DNA of pCPP717 revealed three predicted genes, paaA, paaB and paaC, in a 2.7 kb region. The predicted paaA gene product is similar in sequence to a group of biosynthetic enzymes that possess a dinucleotide binding motif. PaaC was judged to encode a membrane protein. The second antibiotic was named pantocin B. Its synthesis is conferred on E. coli by DNA harbored in clone pCPP719. Between 19 kb and 20 kb of Eh318 DNA is needed for the production of pantocin B. Direct Tn5- and marker-exchange mutants of Eh318, deficient in pantocin A and/or pantocin B, were created. The mutant strains were tested for biocontrol ability in immature pear fruit in the laboratory and in apple blossoms in a controlled environment chamber. Results from both assays revealed that the marker-exchange mutant deficient in both antibiotics (Eh440) protected against fire blight less well than Eh318. The single marker-exchange mutants, Eh421 (deficient in pantocin A) and Eh439 (deficient in pantocin B), were not significantly impaired in biocontrol ability, whereas three directly induced Tn5-mutants, Eh454, Eh464 and Eh468, were less effective than Eh318. Thus, pantocins contribute to but are not solely responsible for the biological control of fire blight by E. herbicola Eh318.
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| 7. |
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| 9. |
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| 10. |
- Dahlgren, Ulf, 1953, et al.
(författare)
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Expression of a dietary protein in E. coli renders it strongly antigenic to gut lymphoid tissue.
- 1991
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Ingår i: Immunology. - 0019-2805. ; 73:4, s. 394-7
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Tidskriftsartikel (refereegranskat)abstract
- Bacteria that colonize the intestinal mucosa elicit a strong mucosal immune response, whereas food antigens such as ovalbumin are very weakly immunogenic to the gut-associated lymphoid tissue. This may either be due to special physico-chemical properties of bacterial substances versus proteins from animals and plants, or to stimulating properties of the bacteria on, e.g., antigen presentation, rendering all substances contained within bacteria antigenic. To test these hypotheses, ovalbumin was expressed in wild-type Escherichia coli and germ-free female rats were colonized with this strain. The systemic and mucosal antibody response of these rats was compared with that of rats given large amounts of dietary ovalbumin. Biliary IgA antibodies, which reflect the local IgA antibody production in the intestine, were only found in the rats colonized with ovalbumin-synthesizing E. coli. IgG antibodies in the bile were also only seen in these rats. We conclude that mucosal immunogenicity depends on the context in which a protein is presented to the gut-associated lymphoid tissue, rather than to special antigenic characteristics of the protein in itself.
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| 11. |
- Herías, M V, et al.
(författare)
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Escherichia coli K5 capsule expression enhances colonization of the large intestine in the gnotobiotic rat.
- 1997
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Ingår i: Infection and immunity. - : American Society for Microbiology. - 0019-9567 .- 1098-5522. ; 65:2, s. 531-6
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Tidskriftsartikel (refereegranskat)abstract
- The role of capsule expression in the capacity of Escherichia coli to colonize in the large intestinal environment was studied in a gnotobiotic rat model. The rats were given perorally a mixture of two mutant strains differing in K5 expression. After 2 weeks, the rats were sacrificed, and subsequently intestinal contents, intestinal mucosae, and mesenteric lymph nodes were homogenized and bacterial numbers were quantified. Two E. coli mutant pairs were used, the first pair (972-998) lacking the O-specific side chain and the second pair (973-997) carrying the O75 lipopolysaccharide. The K5+ mutants established themselves at a higher level than the K5- mutants (10(9) versus 10(6) CFU/g [P < 0.001] for the first pair and 10(9) versus 10(8) CFU/g [P < 0.01] for the second pair, respectively). The results were confirmed by serology showing a K5+ phenotype for practically all isolates. The bacterial population associated with the mucosa was similar to that in the luminal contents with respect to the proportions of the respective mutants, and translocation occurred in numbers proportional to the intestinal population densities of the respective mutants. All mutants were able to express type 1 as well as P fimbriae. After colonization, the expression of P fimbriae remained high whereas only a minority of the isolates expressed type 1 fimbriae. The results suggest that capsule expression and P fimbriae enhance intestinal colonization by E. coli and that these virulence factors, by increasing bacterial densities in the intestine, secondarily increase translocation.
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| 12. |
- Herías, M V, et al.
(författare)
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Role of Escherichia coli P fimbriae in intestinal colonization in gnotobiotic rats.
- 1995
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Ingår i: Infection and immunity. - : American Society for Microbiology. - 0019-9567 .- 1098-5522. ; 63:12, s. 4781-9
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Tidskriftsartikel (refereegranskat)abstract
- Adherence via P fimbriae is associated with long-term persistence of Escherichia coli in the human large intestine, but a causal relationship has not been proven. In the present study, germfree rats were colonized with a mixture of two isogenic E. coli strains, one P fimbriated and the other type 1 fimbriated. Both types of fimbriae conferred adherence to rat colonic epithelial cells. With two mutant strains from a pyelonephritogenic isolate of serotype O75:K5:H-, the P-fimbriated strain 824 attained much higher numbers than its type 1-fimbriated counterpart when colonized in vivo for 2 weeks (10(10) versus 10(6) bacteria per g, respectively; P < 0.0001). The expression of P fimbriae by 824 was also retained during colonization. With transformant isogenic strains obtained from a normal fecal isolate incapable of phase variation, no benefit of P fimbriae was seen and most bacteria lost their plasmids during in vivo colonization. When the pyelonephritogenic mutant and fecal transformant strains were combined, the former colonized at high levels while the latter were suppressed. In contrast, no suppression was seen when the transformant E. coli strains colonized in combination with Lactobacillus acidophilus or Peptostreptococcus sp. The results indicate that P fimbriae, but also other bacterial traits linked to uropathogeneicity, could play an important role for persistence in the gut normal microbiota. Neither P nor type 1 fimbriae seemed to contribute to the ability to translocate to the mesenteric lymph nodes.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
- Kirsebom, L A
(författare)
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RNase P--a 'Scarlet Pimpernel'.
- 1995
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Ingår i: Mol Microbiol. - : Wiley. - 0950-382X .- 1365-2958. ; 17:3, s. 411-20
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Forskningsöversikt (populärvet., debatt m.m.)
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| 17. |
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| 18. |
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| 19. |
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| 20. |
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| 21. |
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| 22. |
- Gustafson, Rolf, et al.
(författare)
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Prevalence of Borrelia burgdorferi sensu lato infection in Ixodes ricinus in Sweden
- 1995
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 27:6, s. 597-601
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Tidskriftsartikel (refereegranskat)abstract
- Between 1988-1991, a total of 3,141 Ixodes ricinus ticks, 2,740 adults and 401 nymphs, was collected from different localities in 23 of the 25 provinces of Sweden. The ticks were identified, dissected and examined for the presence of Borrelia spirochetes. Indirect immunofluorescence was performed, using an antiserum obtained from rabbits, immunized with sonicated, whole Borrelia burgdorferi spirochetes isolated from Swedish Ixodes ricinus ticks. Borrelia-positive I. ricinus were found in all 23 provinces. The prevalence of infection in adults ranged from 3% in Jämtland to 23% in Södermanland. In nymphs, the infection prevalence ranged from 0% in 9 provinces to 15% in Södermanland. A significantly greater proportion of the adult ticks were found to be positive for Borrelia in the southern and central parts of Sweden as compared to the northern part (Norrland). No significant difference in prevalence could be demonstrated between the western and eastern parts of Sweden. On average, 10% of the nymphs and 15% of the adult I. ricinus were positive for Borrelia. Of 41 non-I. ricinus ticks, none was positive for Borrelia. This study shows that Borrelia burgdorferi sensu lato is present throughout the distributional area of I. ricinus in Sweden. This should lead to increased awareness of signs and symptoms compatible with Lyme borreliosis in persons living in or visiting areas where I. ricinus is present.
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| 23. |
- Herías, M V, et al.
(författare)
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Increased antibody production against gut-colonizing Escherichia coli in the presence of the anaerobic bacterium Peptostreptococcus.
- 1998
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Ingår i: Scandinavian journal of immunology. - : Wiley. - 0300-9475 .- 1365-3083. ; 48:3, s. 277-82
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Tidskriftsartikel (refereegranskat)abstract
- Germ-free rats were colonized with E. coli alone, or with E. coli plus Lactobacillus acidophilus and a strain of the obligate anaerobic gram-positive species, Peptostreptococcus. The presence of Peptostreptococcus reduced translocation of E. coli, but increased the serum antibody response to E. coli antigen. Whereas the immunoglobulin G (IgG) anti-E. coli antibodies largely represented cross-reactive antibodies, those of the immunoglobulin M (IgM) isotype represented true anti-E. coli antibodies because they could not be absorbed by L. acidophilus or Peptostreptococcus but could with E. coli. We suggest that peptostreptococci prime the gut immune system to other bacterial antigens and that this could be a mechanism behind the reduced translocation of facultative anaerobes in the presence of obligate anaerobes.
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| 24. |
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| 25. |
- Gustafsson, Lars, et al.
(författare)
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Infectious disease, reproductive effort and the cost of reproduction in birds
- 1994
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Ingår i: Philosophical transactions of the Royal Society of London: Series B. ; :346, s. 1655-1658
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Reproductive effort can have profound effects on subsequent performance. Field experiments on the collared flycatcher (Ficedula albicollis) have demonstrated a number of trade-offs between life-history traits at different ages. The mechanism by which reproductive effort is mediated into future reproductive performance remains obscure. Anti-parasite adaptations such as cell-mediated immunity may probably also be costly. Hence the possibility exists of a trade-off between reproductive effort and the ability to resist parasitic infection. Serological tests on unmanipulated collared flycatchers show that pre-breeding nutritional status correlates positively with reproductive success and negatively with susceptibility to parasitism (viruses, bacteria and protozoan parasites). Both immune response and several indicators of infectious disease correlate negatively with reproductive success. Similar relations are found between secondary sexual characters and infection parameters. For brood-size-manipulated birds there was a significant interaction between experimentally increased reproductive effort and parasitic infection rate with regard to both current and future fecundity. It seems possible that the interaction between parasitic infection, nutrition and reproductive effort can be an important mechanism in the ultimate shaping of life-history variation in avian populations.
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| 26. |
- Förlin, Lars, 1950, et al.
(författare)
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Studier av miljöeffekter hos tånglake
- 1997
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Ingår i: Havsmiljön. - 1104-3458. ; mars 1997, s. 14-15
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 27. |
- Mejlon, Hans, et al.
(författare)
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Seasonal prevalence of Borrelia burgdorferi in Ixodes ricinus in different vegetation types in Sweden
- 1993
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 25:4, s. 449-456
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this investigation was to estimate the seasonal risk of contracting human Lyme disease in different vegetation types in southern Sweden. Host-seeking Ixodes ricinus ticks (Acari: Ixodidae) were collected with standardized methods during May-September 1988 and March-October 1989 at 10 different sampling sites. Tick abundance was greatest during May-June and August-September. Prevalence of Borrelia burgdorferi infection of the ticks was assessed by phase-contrast microscopy complemented by immunology. Spirochetal infection of tick larvae was not detected. The prevalence of infection among nymphal ticks differed significantly between years and between sampling sites. Infection prevalence was greater in adult females than in nymphs, but was similar in female and male ticks. Among all vegetation types studied, the greatest Lyme disease risk was deemed to be from I. ricinus nymphs during May and September in mixed forest vegetation.
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| 28. |
- Adlerberth, Ingegerd, 1959, et al.
(författare)
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A mannose-specific adherence mechanism in Lactobacillus plantarum conferring binding to the human colonic cell line HT-29.
- 1996
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Ingår i: Applied and environmental microbiology. - 0099-2240. ; 62:7, s. 2244-51
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Tidskriftsartikel (refereegranskat)abstract
- Two Lactobacillus plantarum strains of human intestinal origin, strains 299 (= DSM 6595) and 299v (= DSM 9843), have proved to be efficient colonizers of the human intestine under experimental conditions. These strains and 17 other L. plantarum strains were tested for the ability to adhere to cells of the human colonic cell line HT-29.L.plantarum 299 and 299v and nine other L. plantarum strains, including all six strains that belong to the same genetic subgroup as L. plantarum 299 and 299v, adhered to HT-29 cells in a manner that could be inhibited by methyl-alpha-D-mannoside. The ability to adhere to HT-29 cells correlated with an ability to agglutinate cells of Saccharomyces cerevisiae and erythrocytes in a mannose-sensitive manner and with adherence to D-mannose-coated agarose beads. L. plantarum 299 and 299v adhered to freshly isolated human colonic and ileal enterocytes, but the binding was not significantly inhibited by methyl-alpha-D-mannoside. Periodate treatment of HT-29 cells abolished mannose-sensitive adherence, confirming that the cell-bound receptor was of carbohydrate nature. Proteinase K treatment of the bacteria also abolished adherence, indicating that the binding involved protein structures on the bacterial cell surface. Thus, a mannose-specific adhesin has been identified in L. plantarum; this adhesin could be involved in the ability to colonize the intestine.
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| 29. |
- Ahrné, Siv, et al.
(författare)
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The normal Lactobacillus flora of healthy human rectal and oral mucosa.
- 1998
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Ingår i: Journal of applied microbiology. - 1364-5072. ; 85:1, s. 88-94
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Tidskriftsartikel (refereegranskat)abstract
- The Lactobacillus flora of the rectal and oral mucosa was sampled from 42 healthy volunteers. Species identification was carried out by numerically comparing API 50CH fermentation patterns with type strains, using an SJ-similarity cut-off level of 79%. For the largest groups, identity was further confirmed by DNA-DNA hybridizations against the type strain of the species. Seventeen lactobacilli clusters were defined, of which most were found both on rectal and oral mucosa. The largest taxa were Lactobacillus plantarum, Lact. rhamnosus and Lact. paracasei ssp. paracasei, which were isolated from 52%, 26% and 17% of the individuals, respectively. Most isolates were tested for their capacity to adhere to the human colonic cell line HT-29 in the absence and presence of methyl-alpha-D-mannoside. Mannose-sensitive adherence to HT-29 cells was encountered in two-thirds of the Lact. plantarum isolates, but infrequently among isolates of other taxa. The results suggest that Lact. plantarum is a major colonizer of the human gastrointestinal mucosa, and that its capacity to adhere to mannose-containing receptors may be of some ecological importance.
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| 30. |
- Berndtson, Eva, et al.
(författare)
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Campylobacter incidence on a chicken farm and the spread of Campylobacter during the slaughter process
- 1996
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Ingår i: International Journal of Food Microbiology. - : Elsevier. - 0168-1605 .- 1879-3460. ; 32:1-2, s. 35-47
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Tidskriftsartikel (refereegranskat)abstract
- To get a better understanding of the epidemiology of Campylobacter, a chicken farm was studied for 16 weeks with samplings in each flock weekly from input until the flock became colonized with Campylobacter or slaughtered. Samples were taken from fresh droppings and from drinkers during the rearing period, as well as from the environment in empty houses. The spread of Campylobacter during the slaughter process was also surveyed. No Campylobacter was found in samples from newly-hatched ol one-week-old chickens or their drinkers. All Hocks but one were colonized at two to five weeks of age. All Campylobacter isolates belonged to the same sero- and biotype; C. jejuni Penner 2. The spread of Campylobacter in the flock was rapid and usually all samples were positive once colonization had been proven. C. jejuni was isolated from flies in ante-rooms as well as from air in chicken units ill houses with positive chicken flocks. Samples were taken at slaughter when some of the Campylobacter positive Hocks from the farm were slaughtered. Campylobacter were isolated from all sampled equipment along the processing line, from the chicken transport crates to the chillers, as well as from the air.
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| 31. |
- Berndtson, Eva, et al.
(författare)
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Experimental colonization of mice with Campylobacter jejuni
- 1994
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Ingår i: Veterinary Microbiology. - : Elsevier. - 0378-1135 .- 1873-2542. ; 41:1-2, s. 183-188
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Tidskriftsartikel (refereegranskat)abstract
- The ability of one human and two chicken strains of Campylobacter jejuni to colonise and survive in three different strains of laboratory mice (NMRI, CBA and C57-Black) was studied. Mice were inoculated orally with Campylobacter jejuni and faeces samples were cultured at regular intervals during the following months. The length of colonisation of mice differed between mouse strains but also between Campylobacter strains. The mouse strain C57-Black was not colonised with C. jejuni to the same degree as the other mouse strains. It is concluded that mice can become colonised for prolonged periods and that they may act as reservoirs of Campylobacter for other species.
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| 32. |
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| 33. |
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| 34. |
- Pettersson, Jonas, et al.
(författare)
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The V-antigen of Yersinia is surface exposed before target cell contact and involved in virulence protein translocation :
- 1999
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Ingår i: Molecular Microbiology. - : John Wiley & Sons. - 0950-382X .- 1365-2958. ; 32:5, s. 961-976
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Tidskriftsartikel (refereegranskat)abstract
- Type III-mediated translocation of Yop effectors is an essential virulence mechanism of pathogenic Yersinia. LcrV is the only protein secreted by the type III secretion system that induces protective immunity. LcrV also plays a significant role in the regulation of Yop expression and secretion. The role of LcrV in the virulence process has, however, remained elusive on account of its pleiotropic effects. Here, we show that anti-LcrV antibodies can block the delivery of Yop effectors into the target cell cytosol. This argues strongly for a critical role of LcrV in the Yop translocation process. Additional evidence supporting this role was obtained by genetic analysis. LcrV was found to be present on the bacterial surface before the establishment of bacteria target cell contact. These findings suggest that LcrV serves an important role in the initiation of the translocation process and provides one possible explanation for the mechanism of LcrV-induced protective immunity.
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| 35. |
- Johanson, Urban, et al.
(författare)
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Comparison of the complete sequence of the str operon in Salmonella typhimurium and Escherichia coli
- 1992
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Ingår i: Gene. - 0378-1119 .- 1879-0038. ; 120:1, s. 93-98
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Tidskriftsartikel (refereegranskat)abstract
- The nucleotide (nt) sequences of the str operon in Escherichia coli K-12 and Salmonella typhimurium LT2 were completed and compared at the nt and amino acid (aa) level. The order of conservation at the nt and aa level is rpsL greater than tufA greater than rpsG greater than f usA. A striking difference is that the rpsG-encoded ribosomal protein, S7, in E. coli K-12 is 23 aa longer than in S. typhimurium. The very low (0.18) codon adaptation index of this part of the E. coli K-12-encoding gene and the unusual stop codon (UGA) suggest that this is a relatively recent extension. A trend towards a higher G+C content in fusA (gene encoding elongation factor (EF)-G) and tufA (gene encoding EF-Tu) in S. typhimurium is noted. In fusA, nt substitutions at all three positions in a codon occur at a much higher frequency than expected from the number of nt substitutions in the gene, assuming they are random and independent events. An analysis of substitutions in this and other genes suggests that the triple substitutions in fusA, and some other genes, are the result of the sequential accumulation of individual mutations, probably driven by selection pressure for particular codons or aa.
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| 36. |
- Frithz-Lindsten, Elisabet, et al.
(författare)
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Functional conservation of the effector protein translocators PopB/YopB and PopD/YopD of Pseudomonas aeruginosa and Yersinia pseudotuberculosis.
- 1998
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Ingår i: Molecular Microbiology. - : John Wiley & Sons. - 0950-382X .- 1365-2958. ; 29:5, s. 1155-1165
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Tidskriftsartikel (refereegranskat)abstract
- Virulent Yersinia species cause systemic infections in rodents, and Y. pestis is highly pathogenic for humans. Pseudomonas aeruginosa, on the other hand, is an opportunistic pathogen, which normally infects only compromised individuals. Surprisingly, these pathogens both encode highly related contact-dependent secretion systems for the targeting of toxins into eukaryotic cells. In Yersinia, YopB and YopD direct the translocation of the secreted Yop effectors across the target cell membrane. In this study, we have analysed the function of the YopB and YopD homologues, PopB and PopD, encoded by P. aeruginosa. Expression of the pcrGVHpopBD operon in defined translocation-deficient mutants (yopB/yopD) of Yersinia resulted in complete complementation of the cell contact-dependent, YopE-induced cytotoxicity of Y. pseudotuberculosis on HeLa cells. We demonstrated that the complementation fully restored the ability of Y. pseudotuberculosis to translocate the effector molecules YopE and YopH into the HeLa cells. Similar to YopB, PopB induced a lytic effect on infected erythrocytes. The lytic activity induced by PopB could be prevented if the erythrocytes were infected in the presence of sugars larger than 3 nm in diameter, indicating that PopB induced a pore of similar size compared with that induced by YopB. Our findings show that the contact-dependent toxin-targeting mechanisms of Y. pseudotuberculosis and P. aeruginosa are conserved at the molecular level and that the translocator proteins are functionally interchangeable. Based on these similarities, we suggest that the translocation of toxins such as ExoS, ExoT and ExoU by P. aeruginosa across the eukaryotic cell membrane occurs via a pore induced by PopB.
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| 37. |
- Leary, Sophie E. C., et al.
(författare)
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Yersinia outer proteins (YOPS) E, K and N are antigenic but non-protective compared to V antigen, in a murine model of bubonic plague
- 1999
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Ingår i: Microbial Pathogenesis. - : Elsevier. - 0882-4010 .- 1096-1208. ; 26:3, s. 159-169
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Tidskriftsartikel (refereegranskat)abstract
- The pathogenic Yersiniae produce a range of virulence proteins, encoded by a 70 kb plasmid, which are essential for infection, and also form part of a contact-dependent virulence mechanism. One of these proteins, V antigen, has been shown to confer a high level of protection against parenteral infection with Y. pestis in murine models, and is considered to be a protective antigen. In this study, the protective efficacy of V antigen has been compared in the same model with that of other proteins (YopE, YopK and YopN), which are part of the contact-dependent virulence mechanism. Mice immunised with two intraperitoneal doses of V antigen or each of the Yops, administered with either Alhydrogel or interleukin-12, produced high antigen-specific serum IgG titres. As shown in previous studies, V+Alhydrogel was fully protective, and 5/5 mice survived a subcutaneous challenge with 90 or 9x10(3) LD50's of Y. pestis GB. In addition, these preliminary studies also showed that V+IL-12 was partially protective: 4/5 or 3/5 mice survived a challenge with 90 or 9x10(3) LD50's, respectively. In contrast, none of the mice immunised with the Yops survived the challenges, and there was no significant delay in the mean time to death compared to mice receiving a control protein. These results show that using two different vaccine regimens, Yops E, K and N, failed to elicit protective immune responses in a murine model of plague, whereas under the same conditions, V antigen was fully or partially protective.
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| 38. |
- Mattsby-Baltzer, Inger, 1949, et al.
(författare)
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IL-1beta, IL-6, TNFalpha, fetal fibronectin, and endotoxin in the lower genital tract of pregnant women with bacterial vaginosis.
- 1998
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Ingår i: Acta obstetricia et gynecologica Scandinavica. - : Wiley. - 0001-6349. ; 77:7, s. 701-6
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Tidskriftsartikel (refereegranskat)abstract
- In our studies on women with bacterial vaginosis (BV) in early pregnancy a strong association has been found between BV and the levels of endotoxin or interleukin-1alpha (IL-1alpha) in the lower genital tract. In the present study we investigated if an association could be found between BV and other cytokines (IL-1beta, IL-6, tumor necrosis factor alpha, TNF) or fetal fibronectin (FFN). The cytokine-inducing capacity of endotoxins present in the cervical mucus was explored in a monocytic cell assay.Cervical mucus or cervicovaginal fluid was collected from women with (BV) and without BV (nonBV) attending a family planning unit for first trimester abortion. The concentrations of IL-1beta, IL-6, TNF and FFN were determined by quantitative enzyme immunoassays. TNF was determined in 63 women (BV, n=25) out of whom 37 (BV, n=11) were analyzed for IL-1beta and the remaining 26 for IL-6 (BV, n=14). FFN was determined in another 36 women (BV, n= 19). The cytokine-inducing capacity of endotoxin-containing cervical mucus and purified endotoxin of Prevotella bivia were studied by an in vitro cell assay using a human monocytic cell line (THP-1).IL-lbeta and IL-6 were found in almost all women. The levels of IL-1beta, but not IL-6, TNF or FFN, were significantly increased in women with BV compared with the nonBV women (p<0.05). Purified endotoxin from P. bivia, and cervical mucus from BV women containing high levels of endotoxin were able to induce a cytokine response (IL-6) in monocytic cells in vitro.BV is associated with increased levels of IL-1beta in the lower genital tract of pregnant women in the first trimester. The ability of BV-associated endotoxins to induce cytokine production in monocytic cells may partly explain the increased IL-1beta levels.
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| 39. |
- Bunikis, J, et al.
(författare)
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Molecular polymorphism of the Lyme disease agent Borrelia garinii in northern Europe is influenced by a novel enzootic Borrelia focus in the North Atlantic
- 1996
-
Ingår i: Journal of Clinical Microbiology. - Washington, DC, United States : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 34:2, s. 364-368
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Tidskriftsartikel (refereegranskat)abstract
- Lyme disease Borrelia species are distributed in temperate areas of North America and Eurasia. To elucidate the distribution of borreliae in subarctic regions, strains isolated from Ixodes ricinus and Ixodes uriae ticks found on islands in the northern Atlantic and Baltic Sea were molecularly characterized. All isolates were verified as Borrelia garinii by 16S rRNA gene analysis and immunoblotting with monoclonal antibodies specific for the outer surface proteins A and C. Three ribotypes (RTs) of B. garinii were delineated. I. ricinus complex-associated RT1 was phenotypically most heterogeneous. Two newly identified ribotypes were shared by different tick species and conformed to two established OspA serotypes. RT2 was restricted to the islands in the northern Baltic Sea, whereas RT3 was recovered also from ticks found in the North Atlantic. In conclusion, molecular polymorphism of the studied borrelia isolates suggests a complex enzootic potential of B. garinii in northern Europe and implies a novel, seabird tick I. uriae-associated enzootic focus of Lyme disease borreliae in the North Atlantic.
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| 40. |
- Dopson, Mark, et al.
(författare)
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Potential role of thiobacillus caldus in arsenopyrite bioleaching
- 1999
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 65:1, s. 36-40
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the potential role of the three strains of Thiobacillus caldus (KU, BC13, and C-SH12) in arsenopyrite leaching in combination with a moderately thermophilic iron oxidizer, Sulfobacillus thermosulfidooxidans. Pure cultures of T. caldus and S. thermosulfidooxidans were used as well as defined mixed cultures. By measuring released iron, tetrathionate, and sulfur concentrations, we found that the presence of T. caldus KU and BC13 in the defined mixed culture lowered the concentration of sulfur, and levels of tetrathionate were comparable to or lower than those in the presence of S. thermosulfidooxidans. This suggests that T. caldus grows on the sulfur compounds that build up during leaching, increasing the arsenopyrite-leaching efficiency. This result was similar to leaching arsenopyrite with a pure culture of S. thermosulfidooxidans in the presence of yeast extract. Therefore, three possible roles of T. caldus in the leaching environment can be hypothesized: to remove the buildup of solid sulfur that can cause an inhibitory layer on the surface of the mineral, to aid heterotrophic and mixotrophic growth by the release of organic chemicals, and to solubilize solid sulfur by the production of surface-active agents. The results showed that T. caldus KU was the most efficient at leaching arsenopyrite under the conditions tested, followed by BC13, and finally C-SH12.
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| 41. |
- Ericsson, Henrik, et al.
(författare)
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An outbreak of listeriosis suspected to have been caused by rainbow trout
- 1997
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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 35:11, s. 2904-2907
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Tidskriftsartikel (refereegranskat)abstract
- An outbreak of listeriosis in Sweden, consisting of nine cases, was investigated by means of molecular typing of strains from patients and strains isolated from suspected foodstuffs, together with interviews of the patients. Listeria monocytogenes was isolated from six of the patients, and all isolates were of the same clonal type. This clonal type was also isolated from a 'gravad' rainbow trout, made by producer Y, found in the refrigerator of one of the patients. Unopened packages obtained from producer y were also found to contain the same clonal type of L. monocytogenes. Based on the interview results and the bacteriological typing, we suspect that at least six of the nine cases were caused by gravad or cold-smoked rainbow trout made by producer Y. To our knowledge, this is the first rainbow trout-borne outbreak of listeriosis ever reported.
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| 42. |
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| 43. |
- Hallberg, K. B., et al.
(författare)
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Arsenic toxicity is not due to a direct effect on the oxidation of reduced inorganic sulfur compounds byThiobacillus caldus
- 1996
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Ingår i: FEMS Microbiology Letters. - 0378-1097 .- 1574-6968. ; 145:3, s. 409-414
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Tidskriftsartikel (refereegranskat)abstract
- Thiobacillus caldus is a moderately thermophilic acidophile which has been implicated in the biooxidation of arsenic containing mineral sulfides. The toxic effects of arsenic on this bacterium are presented here. Addition of arsenite to a growing culture of T. caldus caused a transient increase in the optical density of the culture while causing a simultaneous decrease in cell viability. The increase in optical density was shown to be due to the formation of extracellular sulfur. The oxidation rates of tetrathionate and thiosulfate were decreased by increasing concentrations of arsenite, while in a culture induced to arsenic resistance the rates were not as adversely effected. Sulfur oxidation was also inhibited to the same extent as tetrathionate oxidation, with the oxidation of solid sulfur being slightly more effected than the oxidation of sulfur dissolved in acetone. Thus, bactericidal arsenite causes a transient formation of extracellular sulfur in the culture supernatant of T. caldus yet the toxicity of arsenite is not due to direct inhibitory effects on reduced inorganic sulfur compound oxidation by these bacteria.
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| 44. |
- Hallberg, K B, et al.
(författare)
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Reduced sulfur compound oxidation by Thiobacillus caldus.
- 1996
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Ingår i: Journal of Bacteriology. - 0021-9193 .- 1098-5530. ; 178:1, s. 6-11
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Tidskriftsartikel (refereegranskat)abstract
- The oxidation of reduced inorganic sulfur compounds was studied by using resting cells of the moderate thermophile Thiobacillus caldus strain KU. The oxygen consumption rate and total oxygen consumed were determined for the reduced sulfur compounds thiosulfate, tetrathionate, sulfur, sulfide, and sulfite in the absence and in the presence of inhibitors and uncouplers. The uncouplers 2,4-dinitrophenol and carbonyl cyanide m-chlorophenyl-hydrazone had no affect on the oxidation of thiosulfate, suggesting that thiosulfate is metabolized periplasmically. In contrast, the uncouplers completely inhibited the oxidation of tetrathionate, sulfide, sulfur, and sulfite, indicating that these compounds are metabolized in the cytoplasm of T. caldus KU. N-Ethylmaleimide inhibited the oxidation of tetrathionate and thiosulfate at the stage of elemental sulfur, while 2-heptyl-4-hydroxyquinoline-N-oxide stopped the oxidation of thiosulfate, tetrathionate, and elemental sulfur at the stage of sulfite. The following intermediates in the oxidation of the sulfur compounds were found by using uncouplers and inhibitors: thiosulfate was oxidized to tetrathionate, elemental sulfur was formed during the oxidation of tetrathionate and sulfide, and sulfite was found as an intermediate of tetrathionate and sulfur metabolism. On the basis of these data we propose a model for the metabolism of the reduced inorganic sulfur compounds by T. caldus KU.
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| 45. |
- Hellers, Marianne, 1962-
(författare)
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Expression and processing of cecropin and attacin using a baculovirus vector
- 1992
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The cecropins and attacins are two antibacterial peptides induced uponimmunization in the moth Hyalophora cecropia. They are both synthesized aspreproproteins that are processed and post-translationally modified along the exportpathway.To study these processing and modification events, the baculovirus expressionvector system was employed as a model system. The strong polyhedrin promoter ofAutographa californica nuclear polyhedrosis virus (AcNPV) was used to driveexpression of different forms of cecropin and attacin. To successfully express thesesmall proteins that are sensitive to proteolysis, Trichoplusia ni larvae and H.cecropia pupae were used instead of Spodoptera frugiperda cell culture. Therecombinant proteins produced by living animals were biologically active, accuratelyprocessed and the cecropins were C-terminally amidated.The amidation machinery of H. cecropia was further investigated. It was foundthat enzymes needed for amidation are present in small amounts in both fat body andhemolymph of H. cecropia pupae, and that a bacterial infection causes an increase ofthe amidation activity, indicating a coregulation of the immune proteins and theenzymes needed for their processing.In order to establish that T. ni was a suitable host for heterologous expression of theantibacterial peptides, the endogeneous immune response of the larvae wasinvestigated and it was ascertained that the immune proteins do not have a deleteriouseffect on AcNPV.The potential of diapausing H. cecropia pupae as expression host was explored byexpressing four different recombinant proteins. It was shown that H. cecropia pupaecompare favourably as expression host to T. ni larvae.
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| 46. |
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| 47. |
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| 48. |
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| 49. |
- Larsson, U., et al.
(författare)
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Pelagic bacterial and phytoplankton in a subtropical marine environment exposed to chronic oil contamination.
- 1990
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Ingår i: Oil and Chemical Pollution. - 0269-8579. ; 7:2, s. 129-142
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Tidskriftsartikel (refereegranskat)abstract
- The abundance and production of pelagic bacteria, phytoplankton primary production and chlorophyll content were studied in coastal waters receiving the effluent from an oil refinery in the Arabian Gulf. The area also receives unknown amounts of other effluents rich in organic matter and nutrients. The abundance of bacteria was measured by epifluorescent direct counts, and productivity was estimated by 3H-thymidine uptake measurements. The results showed a clear stimulation of the primary productivity as well as elevated amounts of chlorophyll a in the area receiving the effluent. Both bacterial abundances and production were an order of magnitude higher in a small area close to the refinery outlet, but dropped rapidly and reached background values outside an impacted area of c 10 km2. The increased bacterial production in this area corresponded to a substrate demand of 4 to 11 tonnes of carbon per day, 4 to 12 times the daily discharge of some 0·9 tonnes of carbon in the form of petroleum hydrocarbons from the oil refinery. These data, plus the low petroleum hydrocarbon concentrations found in the sediments and in bivalves outside the impacted area, suggest that bacterial degradation of the petroleum hydrocarbons from the refinery could be a major process restricting the area impacted by oil pollution.
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| 50. |
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