| 1. |
- Lundqvist, Carina, et al.
(författare)
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Intra-epithelial lymphocytes. Evidence for regional specialization and extrathymic T cell maturation in the human gut epithelium
- 1995
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Ingår i: International Immunology. - : Oxford University Press (OUP). - 0953-8178 .- 1460-2377. ; 7:9, s. 1473-1487
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Tidskriftsartikel (refereegranskat)abstract
- The human gut epithelium is a unique immunological compartment, containing substantial amounts of intra-epithelial lymphocytes (IEL) with unknown functions. In this study we show that distinct and unusual subpopulations of IEL are present at different levels of human intestine. IEL phenotypes in normal jejunum, ileum and colon were compared using immunoflow cytometry and immunohistochemistry. The expression of mRNA for recombination-activating gene-1 (RAG-1) in IEL from all three levels was compared using reverse-transcription polymerase chain reaction, and the morphology of IEL in situ was determined using immunoelectron microscopy. Surface marker profiles of isolated intestinal epithelial cells at all three levels were also investigated. On average the proportion of TCR gamma delta IEL was comparable in jejunum than ileum and colon and varied in phenotype with gut level. CD4-CD8-TCR alpha beta IEL dominated in colon but were absent in jejunum. CD8+ TCR alpha beta IEL were present at all levels but only in jejunum did they constitute the majority of all IEL. CD4+ TCR alpha beta IEL were present in similar frequencies at all levels of the gut. In general, the majority of IEL had an activated phenotype (CD45RO+, alpha E beta 7+). Furthermore, IEL exhibited phenotypes which are rare in peripheral blood. The thymocyte markers CD1a and CD1c as well as the NK cell marker CD56 were expressed on a fraction of TCR alpha beta and TCR gamma delta IEL. A small population of 'null' cells (CD45+ TCR/CD#-CD20-CD14-CD15- cells) was also present at equal proportions along the gut. Jejunal but not colonic IEL expressed RAG-1 mRNA suggesting that extrathymic T cell maturation occurs in the epithelium of small intestine. RAG-1 was expressed in CD2+TCR/CD3- and CD3+/TCR-IEL. Ultrastructurally, IEL often formed small clusters and intimate contacts with epithelial cells, suggesting cell cooperation within the epithelium. Some IEL had pseudopodium-like extensions penetrating the epithelial basement membrane suggesting transmigration. Epithelial cells in small intestine but not colon expressed heat shock protein 60 and HLA-DR. CD1a, CD1b and CD1c were not expressed on intestinal epithelial cells at any level. The distinct surface marker profiles of IEL and epithelial cells along small and large intestine suggest functional regional specialization and are compatible with the hypothesis that TCR alpha beta IEL participate in immune reactions to lumenal antigens while TCR gamma delta IEL perform surveillance of the epithelium.
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| 2. |
- Andersson, Mikael, et al.
(författare)
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Effect of bilayer phase transitions on vesicle structure and its influence on the kinetics of viologen reduction.
- 1995
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Ingår i: Journal of physical chemistry. - 0022-3654. ; 99:39, s. 14531-14538
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Vesicles were prepared from pure phosphatidylcholines (PC), phosphatidic acids (PA), or dioctadecyldimethylamonium bromide (DODAB). The aggregate structure was examined above and below the gel-to-liquid crystalline transition temperature (T-m) by means of cryo-transmission electron microscopy. The redox reaction between a membrane bound viologen and dithionite was studied in the different lipid systems. It was found that the presence of faceted vesicles or open bilayer fragments, below T-m, lead to double-exponential reduction kinetics.
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| 3. |
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| 4. |
- Hammarström, Leif, et al.
(författare)
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Artificial photosynthesis: towards functional mimics of photosystem II?
- 1998
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Ingår i: Biochimica et Biophysica Acta - Bioenergetics. - 0005-2728. ; 1365:1-2, s. 193-199
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the initial development of a project aiming at the construction of functional mimics of the oxygen-evolving complex of photosystem II, coupled to photoinduced charge separation. Biomimetic electron donors, manganese complexes and tyrosine, have been linked to a Ru(II)-polypyridine photosensitiser. Oxidation of the donors by intramolecular electron transfer from the photo-oxidised Ru(III) complex was demonstrated using optical flash photolysis and EPR experiments. A step-wise electron transfer Mn->tyrosine->Ru(III) was demonstrated.
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| 5. |
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| 6. |
- Hammarström, Leif, et al.
(författare)
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Cryo-TEM Evidence : Sonication of Dihexadecyl Phosphate Does Not Produce Closed Bilayers with Smooth Curvature
- 1995
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 11:2, s. 408-410
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Dihexadecyl phosphate (DHP) is commonly used for formation of model membranes. In this report cryo-transmission electron microscopy (cryo-TEM) pictures are presented. They clearly show that after cooling to room temperature, dispersions of DHP sonicated at 80 degrees C are dominated by open and folded bilayer fragments, rather than by vesicles with smooth curvature. Quantitative results of an earlier kinetic investigation of viologen reduction in DHP were reproduced using these dispersions.
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| 7. |
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| 8. |
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| 9. |
- Hammarström, Leif, et al.
(författare)
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Mimicking Photosystem II Reactions in Artificial Photosynthesis
- 1999
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Ingår i: Zeitschrift für Physikalische Chemie. - 0942-9352. ; 213:2, s. 157-163
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Tidskriftsartikel (refereegranskat)abstract
- The paper describes a project aiming at the construction of functional mimics of the oxygen evolving complex of Photosystem II, coupled to photoinduced charge separation. Biomimetic electron donors - manganese complexes and tyrosine - have been linked to a Ru(II)-polypyridine photosensitizer. Oxidation of the donors by intramolecular electron transfer from the photo-oxidized Ru(III) complex was demonstrated using optical flash photolysis and EPR experiments. A step-wise electron transfer Mn → tyrosine → Ru(III) was demonstrated, in a sequence analogous to reactions of the PSII donor side.
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| 10. |
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