| 1. |
- Penston, M. V., et al.
(författare)
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The extended narrow line region of NGC 4151. I. Emission line ratios and their implications
- 1990
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 236:1, s. 53-6262
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents the first results from long-slit spectra of the Seyfert galaxy NGC 4151 which give average diagnostic ratios of weak lines in the extended narrow line region (ENLR) of that galaxy and the first direct density measurement in an ENLR. These data confirm that the ENLR is kinematically undisturbed gas in the disc of the galaxy which is illuminated by an ionizing continuum stronger by a factor of 13 than a power law interpolated between observed ultraviolet and X-ray fluxes. Explanations of this apparent excess include a hot thermal continuum, time variations and an anisotropic radiation field. The authors give reasons for favouring anisotropy which might be caused by shadowing by a thick accretion disc or by relativistic beaming. Shadowing by a molecular torus is unlikely, given the absence of an infrared signal from the reradiated flux absorbed by any torus. Anisotropy would have important implications for the bolometric luminosity and nature of active galactic nuclei
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| 2. |
- Sargeson, A. M., et al.
(författare)
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Names and symbols of transfermium elements (IUPAC recommendations 1994)
- 1994
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Ingår i: Pure and Applied Chemistry. - : Walter de Gruyter GmbH. - 0033-4545 .- 1365-3075. ; 66:12, s. 2419-2421
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Tidskriftsartikel (refereegranskat)abstract
- The Transfermium Working Group (TWG) was set up in 1986 under the joint auspices of the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics (IUPAP). Its conclusions, duly endorsed by IUPAC and IUPAP, were published in the following three reports:1. Criteria that must be satisfied for the discovery of a new chemical element to be recognized, Pure & Appl. Chem., 63, 879-886 (1991).2. Discovery of the transfermium elements: Introduction to the discovery profiles, Pure & Appl. Chem., 65, 1757-1763 (1993).3, Discovery of the transfermium elements: Discovery profiles of the transfermium elements, Pure & Appl. Chem., 65, 1764-1814 (1993).IUPAC went a stage further by inviting responses on reports 2 and 3 from the three major groups concerned, i.e., Lawrence Berkeley Laboratory, California; Joint Institute for Nuclear Research, Dubna; and Gesellschaft fur Schwerionenforschung , Darmstadt. These responses together with the TWG's reply to the responses were published unedited in Pure & Appl. Chem.,Vol. 65, (1993), pp. 1815-1824.
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| 3. |
- Knipp, D.J., et al.
(författare)
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Ionospheric Convection Response to Slow, Strong Variations in a Northward Interplanetary Magnetic Field: A Case Study for January 14, 1988
- 1993
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 98, s. 19273-19292
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Tidskriftsartikel (refereegranskat)abstract
- We analyze ionospheric convection patterns over the polar regions during the passage of an interplanetary magnetic cloud on January 14, 1988, when the interplanetary magnetic field (IMF) rotated slowly in direction and had a large amplitude. Using the assimilative mapping of ionospheric electrodynamics (AMIE) procedure, we combine simultaneous observations of ionospheric drifts and magnetic perturbations from many different instruments into consistent patterns of high-latitude electrodynamics, focusing on the period of northward IMF. By combining satellite data with ground-based observations, we have generated one of the most comprehensive data sets yet assembled and used it to produce convection maps for both hemispheres. We present evidence that a lobe convection cell was embedded within normal merging convection during a period when the IMF B(y) and B(z) components were large and positive. As the IMF became predominantly northward, a strong reversed convection pattern (afternoon-to-morning potential drop of around 100 kV) appeared in the southern (summer) polar cap, while convection in the northern (winter) hemisphere became weak and disordered with a dawn-to-dusk potential drop of the order of 30 kV. These patterns persisted for about 3 hours, until the IMF rotated significantly toward the west. We interpret this behavior in terms of a recently proposed merging model for northward IMF under solstice conditions, for which lobe field lines from the hemisphere tilted toward the Sun (summer hemisphere) drape over the dayside magnetosphere, producing reverse convection in the summer hemisphere and impeding direct contact between the solar wind and field lines connected to the winter polar cap. The positive IMF B(x) component present at this time could have contributed to the observed hemispheric asymmetry. Reverse convection in the summer hemisphere broke down rapidly after the ratio \textbackslashB(y)/B(z)\textbackslash exceeded unity, while convection in the winter hemisphere strengthened. A dominant dawn-to-dusk potential drop was established in both hemispheres when the magnitude of B(y) exceeded that of B(z), with potential drops of the order of 100 kV, even while B(z) remained northward. The later transition to southward B(z) produced a gradual intensification of the convection, but a greater qualitative change occurred at the transition through \textbackslashB(y)/B(z)\textbackslash = 1 than at the transition through B(z) = 0. The various convection patterns we derive under northward IMF conditions illustrate all possibilities previously discussed in the literature: nearly single-cell and multicell, distorted and symmetric, ordered and unordered, and sunward and antisunward.
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| 4. |
- Dietrich, M., et al.
(författare)
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Monitoring of active galactic nuclei. IV. The Seyfert 1 galaxy NGC 4593
- 1994
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 284:1, s. 33-4343
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Tidskriftsartikel (refereegranskat)abstract
- Results of a five-month campaign of optical monitoring the Seyfert 1 galaxy NGC 4593 are presented. High resolution Halpha and Hbeta spectra and direct images in the Johnson U, B, V, R and I bands were obtained between January and June 1990. The emission lines and the continuum showed strong variations on time scales of weeks to days. The Halpha line varied by more than 30% within only 5 days. Cross-correlating the light curves of the Balmer lines with that of the optical continuum gives a lag of around 4 days. Therefore, this low luminosity Seyfert galaxy may have one of the smallest broad line regions known so far
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| 5. |
- Stirpe, G. M., et al.
(författare)
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Monitoring of active galactic nuclei. V. The Seyfert 1 galaxy Markarian 279
- 1994
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 285:3, s. 857-867867
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Tidskriftsartikel (refereegranskat)abstract
- For pt. IV see ibid., vol.284, no.1, p.33-43 (1994). Reports on the Lovers of Active Galaxies' (LAG) monitoring of the Seyfert 1 galaxy Markarian 279 from January to June 1990. The source, which was in a very bright state, gradually weakened after the first month of monitoring: the Halpha and Hbeta flux decreased by 20% and 35% respectively, and the continuum under Halpha by 30%. The luminosity-weighted radius of the broad line region (BLR), as derived from the cross-correlation function, is of the order of 10 light days. This result is very uncertain because the features in the light curves are very shallow, but it is unlikely that the radius of the BLR is more than 1 light month. The profile variations of Halpha confirm that the prevailing motions are not radial. The data of the present campaign and those obtained in previous years, when the source was in a much weaker state, show that the red asymmetry of the Balmer lines correlates positively with the broad line flux. This new effect is briefly discussed
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| 6. |
- Wanders, I., et al.
(författare)
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Spectroscopic monitoring of active galactic nuclei. II. The Seyfert-1 galaxy NGC 3516
- 1993
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 269:1-2, s. 39-5353
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Tidskriftsartikel (refereegranskat)abstract
- The authors present the results of a five month spectroscopic monitoring campaign of the Seyfert-1 galaxy NGC 3516. Using a new calibration method and applying a correction for seeing differences during the various observations they can scale the spectra to each other with a much higher accuracy than hitherto achieved. NGC 3516 shows large amplitude variations on a time scale of several weeks. Asymmetric profile variations occur on the same time scale as the continuum variations. The authors show the presence of a varying dip on the blue wing of the Hbeta profile, which is not present on the Halpha profile, and which corresponds to the absorption features previously seen in the UV emission lines of NGC 3516. From cross-correlation analysis they find a time lag of 14plusmn2 days for the Halpha and 7plusmn3 days for the Hbeta emission-line response to continuum variations
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| 7. |
- Jackson, N., et al.
(författare)
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Monitoring of active galactic nuclei. I. The quasars 1302-102 and 1217+023
- 1992
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 262:1, s. 17-2525
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Tidskriftsartikel (refereegranskat)abstract
- Presents the results of a five-month spectroscopic monitoring campaign of two radio-loud quasars PKS 1217+023 and PKS 1302-102. There is a pronounced lack of variability in 1302-102 apart from a possible small change in the continuum level near the end of the monitoring period, but 1217+023 underwent a 20% continuum decrease in the middle of the campaign. No line variability at all was observed. The co-added data represent two of the best spectra yet obtained of any radio-loud quasar other than 3C 273, and the shape of the Hbeta line and the presence underneath it of other contaminating lines are well determined. The Hbeta broad line in 1302-102 is redshifted by 3 Aring with respect to the narrow line region and there is evidence for a separate broad Hbeta feature on top of the main Hbeta emission in both quasars. This feature is stronger in 1217+023 than in 1302-102
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| 8. |
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| 9. |
- Salamanca, I., et al.
(författare)
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Spectroscopic monitoring of active galactic nuclei. III. Size of the broad line region in NGC 3227
- 1994
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 282:3, s. 742-752752
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Tidskriftsartikel (refereegranskat)abstract
- For pt.II see ibid., vol.269, no.1-2, p.39-53 (1993). The authors present the results of a five-month monitoring campaign of the active galactic nucleus in NGC 3227. The Hbeta and Halpha emission lines and the optical continuum have been analysed. The optical AGN continuum and the broad-line region (BLR) emission in NGC 3227 appear to vary by about 40% on a timescale of 1.5 month. The levels of the broad-line emission and the 675.0 nm continuum are well correlated, a fact consistent with the assumption that the BLR material is photoionised by the central continuum source. Cross-correlation analyses between the light curves of the 675.0 nm AGN continuum and the BLR H emission indicate that the lag of the BLR emission with respect to the continuum variations is 17plusmn7 days. This result suggests that the BLR clouds that are affected by the changes in the flux of the central ionising source lie about 17 light days away from it
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| 10. |
- Söderström, K, et al.
(författare)
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High expression of V gamma 8 is a shared feature of human gamma delta T cells in the epithelium of the gut and in the inflamed synovial tissue.
- 1994
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Ingår i: Journal of Immunology. - 0022-1767 .- 1550-6606. ; 152:12, s. 6017-27
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Tidskriftsartikel (refereegranskat)abstract
- We have analyzed the V-gene usage in gamma delta T cells of the human gut and joint by using a new mAb (B18) specific for V gamma 8 of human TCR-gamma delta+ T cells. The B18+ population constituted a minor subset of the gamma delta T cells in peripheral blood (PB) of healthy persons (6 +/- 5%) and only 1 of 35 gamma delta T cell clones analyzed was positive. In contrast, the B18+ subset was a dominant gamma delta T cell population among intraepithelial lymphocytes (IEL) derived from the human intestine (74 +/- 29, p < 0.002), and two of three IEL clones from patients with coeliac disease were B18+. Interestingly, a higher proportion of B18+ gamma delta T cells was found in the synovial fluid of patients with rheumatoid arthritis (RA) (21 +/- 18%, 0.02 < p < 0.05) compared with normal PB. Furthermore, the B18+ subset was more frequent among IL-2-expanded gamma delta T cells (42 +/- 20%) derived from synovial tissue than among IL-2-expanded cells derived from synovial fluid (p < 0.002) and PB from RA patients (p < 0.02) as well as normal PB (p < 0.002). The V-gene usage of 13 gamma delta T cell clones from the synovial fluid of arthritic patients was analyzed. All B18+ clones (n = 7) expressed mRNA for V gamma 8 together with mRNA for V delta 1 (n = 5) or mRNA for V delta 3 (n = 2). None of the B18- clones expressed V gamma 8 (n = 6). We conclude that the gamma delta T cell that expresses V gamma 8, together with mainly V delta 1, is a major gamma delta T cell subset among the IEL of the gut and a highly frequent subset in the synovial tissue of patients with RA. This subset may correspond to the mouse V gamma 7+ IEL, which has a high degree of amino acid sequence homology with the human V gamma 8 protein.
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| 11. |
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| 12. |
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- De Cossío, Maria E Fernández, et al.
(författare)
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Human monoclonal antibodies against an epitope on the class 5c outer membrane protein common to many pathogenic strains of Neisseria meningitidis
- 1992
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Ingår i: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 0022-1899 .- 1537-6613. ; 166:6, s. 1322-1328
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Tidskriftsartikel (refereegranskat)abstract
- Neisseria meningitidis is a causative agent of meningitis. Despite vaccination programs, it still causes a large number of deaths in young children. Early diagnosis followed by passive immunization with human monoclonal antibodies could be an approach to effective therapy. Peripheral blood lymphocytes from normal, healthy blood donors and from vaccinated individuals were immunized in vitro, using outer membrane proteins purified from A. meningitidis B:4:P1,15. The immunized human B cells were Epstein-Barr virus transformed and fused to a heteromyeloma. Several stable human hybridoma cell lines were established and two, secreting antibodies against the 31-kDa class 5c outer membrane protein, were characterized further. The human antibodies were of IgG1 and IgG3 isotypes, with κ light chains. The recognized epitope was commonly found among pathogenic strains of N. meningitidis; thus, these human monoclonal antibodies may be important in the evaluation of N. meningitidis infections.
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| 20. |
- Hillarp, A, et al.
(författare)
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The human C4b-binding protein beta-chain gene
- 1993
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Ingår i: The Journal of biological chemistry. - 0021-9258. ; 268:20, s. 23-15017
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Tidskriftsartikel (refereegranskat)abstract
- Human complement component C4b-binding protein (C4BP) is composed of seven alpha-chains and one beta-chain. The alpha- and beta-chains are homologous and both contain multiple copies of short consensus repeats (SCR) and in addition carboxyl-terminal non-repeat regions. Each of the alpha-chains contains a binding site for C4b, whereas the beta-chain binds protein S, a vitamin K-dependent protein involved in the regulation of blood coagulation. The alpha- and beta-chain genes are closely linked in the regulators of complement activation gene cluster on the long arm of human chromosome 1, band 1q32. The human beta-chain gene which has now been characterized was found to span more than 10 kilobases of DNA. The presence of at least two different beta-chain gene transcripts was suggested by the isolation of two new cDNA clones which contained different sequences in their extended 5'-untranslated regions. Northern blot analysis demonstrated that the two clones represented distinct beta-chain mRNAs with different 5' end sequences. One class of beta-chain mRNA (denoted A19) was found to be encoded by six exons and primer extension, and S1 nuclease protection assays revealed multiple closely spaced transcription start sites for this mRNA class. Its 5'-untranslated region and signal peptide was encoded by the first exon. The second class of mRNA (denoted A12) had a different transcription start site and its 5'-untranslated region was derived from at least three exons out of which the last one was formed by utilization of an acceptor splice site within the first A19 exon. Exons encoding the mature beta-chain and the 3'-untranslated region were common to both classes of mRNA. The beta-chain contains three SCRs, out of which the first and second are encoded by individual exons, whereas two exons encode the third SCR. The exon encoding the carboxyl-terminal part of the third SCR also encodes 14 amino acids of the non-repeat region. The last exon encodes the remaining 46 carboxyl-terminal amino acids and the entire 3'-untranslated region. The elucidation of the organization of the beta-chain gene provides insight into the sophisticated molecular structure of C4BP and a basis for future structural and functional studies.
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| 21. |
- Olsson, U, et al.
(författare)
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Effects of selenium deficiency on xenobiotic-metabolizing and other enzymes in rat liver.
- 1993
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Ingår i: International Journal for Vitamin and Nutrition Research. - 0300-9831 .- 1664-2821. ; 63:1
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Tidskriftsartikel (refereegranskat)abstract
- The present study was undertaken to characterize effects of selenium (Se) deficiency on 16 enzymes recovered in either one or more of the subcellular fractions of rat liver (as a basis for future studies on the mechanisms underlying the observed changes). Male rats were fed a Torula-yeast based diet with 0.23 mg Se/kg or the same diet with 0.009 mg Se/kg, from weaning and for 10 weeks. Statistically significant effects of Se deficiency were the following: Se-dependent glutathione peroxidase decreased to 0.14% of the Se-adequate controls, while cytosolic glutathione transferase increased 3-fold in Se deficiency when CDNB was the substrate, but decreased significantly when trans-stilbene oxide (diagnostic for subunit 4) was used as the substrate. Cytosolic DT-diaphorase increased about 7-fold in Se deficiency. Further, DT-diaphorase in the microsomal fraction was also significantly increased in Se deficiency, as were the microsomal and mitochondrial epoxide hydrolases and microsomal glutathione transferase. Furthermore, increased activity of the peroxisomal marker enzyme catalase (P < 0.05) was noted in Se-deficient rats. It is our working hypothesis that changes in enzyme activities in Se deficiency are mainly due to changed levels of endogenously generated metabolites or altered functions of endocrine tissues.
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| 22. |
- Pardo-Manuel, F, et al.
(författare)
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Human genes for the alpha and beta chains of complement C4b-binding protein are closely linked in a head-to-tail arrangement
- 1990
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 87:12, s. 32-4529
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Tidskriftsartikel (refereegranskat)abstract
- C4b-binding protein (C4BP) is an important component in the regulation of the complement system and also binds the anticoagulant vitamin K-dependent protein S. These activities are performed by distinct, although structurally related, polypeptides of 70 kDa (alpha chain) and 45 kDa (beta chain), respectively. In this report we have investigated the genetic relationships between these polypeptides. Using pulsed field gel electrophoresis analysis we demonstrate that the genes coding for the alpha (C4BP alpha) and beta (C4BP beta) chains are closely linked within the regulator of complement activation gene cluster. In addition, we have determined that the 3' end of the C4BP beta gene lies 3.5-5 kilobases from the 5' end of the C4BP alpha gene. These findings support the concept that the C4BP alpha and C4BP beta genes are the result of a gene duplication event.
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| 23. |
- Pasker-de Jong, P. C., et al.
(författare)
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Psychopharmaceuticals and perinatal deaths
- 1992
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Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - 0001-6349 .- 1600-0412. ; 71:6, s. 492-3
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Tidskriftsartikel (refereegranskat)
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| 24. |
- Wold, Agnes E, 1955, et al.
(författare)
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Resident colonic Escherichia coli strains frequently display uropathogenic characteristics.
- 1992
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Ingår i: The Journal of infectious diseases. - 0022-1899. ; 165:1, s. 46-52
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial factors associated with long-term persistence in the colon have not been defined. Individual Escherichia coli strains in the colonic flora of 13 schoolgirls with asymptomatic bacteriuria were identified by electromorphic typing of chromosomally encoded enzymes and defined as resident or transient. The strains were characterized as to serotype, receptor specificity, and adherence to the human colonic epithelial cell line HT-29. Colonic resident strains expressed P fimbriae, adhered to colonic epithelial cells via a mannose-resistant mechanism, and expressed the uropathogenic serotypes O1, O2, O6, O7, O18, O25, or O75 more often than did the transient strains, which were often nontypeable. The serotype and hemagglutination pattern were generally retained during intestinal carriage, in contrast to the loss of such properties upon prolonged colonization of the urinary tract. P fimbriae with Gal alpha 1----4Gal beta-specific adherence may, in fact, have evolved to increase persistence in the colon.
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| 25. |
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