| 1. |
- Forsberg, Maria, 1973-, et al.
(författare)
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Activation of Rac2 and Cdc42 on Fc and complement receptor ligation in human neutrophils
- 2003
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 74:4, s. 611-619
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Tidskriftsartikel (refereegranskat)abstract
- Phagocytosis is a complex process engaging a concerted action of signal-transduction cascades that leads to ingestion, subsequent phagolysosome fusion, and oxidative activation. We have previously shown that in human neutrophils, C3bi-mediated phagocytosis elicits a significant oxidative response, suggesting that activation of the small GTPase Rac is involved in this process. This is contradictory to macrophages, where only Fc receptor for immunoglobulin G (FcγR)-mediated activation is Rac-dependent. The present study shows that engagement of the complement receptor 3 (CR3) and FcγR and CR3- and FcγR-mediated phagocytosis activates Rac, as well as Cdc42. Furthermore, following receptor-engagement of the CR3 or FcγRs, a downstream target of these small GTPases, p21-activated kinase, becomes phosphorylated, and Rac2 is translocated to the membrane fraction. Using the methyltransferase inhibitors N-acetyl-S-farnesyl-L-cysteine and N-acetyl-S-geranylgeranyl-L-cysteine, we found that the phagocytic uptake of bacteria was not Rac2- or Cdc42-dependent, whereas the oxidative activation was decreased. In conclusion, our results indicate that in neutrophils, Rac2 and Cdc42 are involved in FcR- and CR3-induced activation and for properly functioning signal transduction involved in the generation of oxygen radicals.
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| 2. |
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| 4. |
- Bergh Thorén, Fredrik, 1976, et al.
(författare)
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A hepatitis C virus-encoded, nonstructural protein (NS3) triggers dysfunction and apoptosis in lymphocytes: role of NADPH oxidase-derived oxygen radicals
- 2004
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Ingår i: Journal of leukocyte biology. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 76:6, s. 1180-6
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Tidskriftsartikel (refereegranskat)abstract
- The persistent infection caused by hepatitis C virus (HCV) is presumably explained by a deficient immune response to the infection, but the basis for the inefficiency of immune-mediated virus eradication is not known in detail. This study addresses mechanisms of relevance to dysfunction of cytotoxic lymphocytes in HCV infection, with a focus on the role of phagocyte-derived oxygen radicals. We show that NS3, a nonstructural, HCV-encoded protein, induces a prolonged release of oxygen radicals from mononuclear and polymorphnuclear phagocytes by activating a key enzyme in radical formation, the reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. The NS3-activated phagocytes, in turn, induced dysfunction and/or apoptosis in three major subsets of lymphocytes of relevance to defense against HCV infection: CD3+/56- T cells, CD3-/56+ natural killer (NK) cells, and CD3+/56+ NKT cells. Two inhibitors of the NADPH oxidase, histamine and diphenylene iodonium, suppressed the NS3-induced oxygen radical production and efficiently protected lymphocytes against NS3-induced apoptosis and dysfunction. In conclusion, we propose that NS3, by triggering oxygen radical formation in phagocytes, may contribute to the dysfunction of antiviral lymphocytes in HCV-infected liver tissue and that strategies to circumvent oxidative stress may be useful in preventing HCV-associated carcinogenesis and facilitating lymphocyte-mediated clearance of infected cells.
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| 5. |
- Hansson, Markus, et al.
(författare)
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Activation of cytotoxic lymphocytes by interferon-alpha: role of oxygen radical-producing mononuclear phagocytes
- 2004
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Ingår i: J Leukoc Biol. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 76:6, s. 1207-13
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Tidskriftsartikel (refereegranskat)abstract
- A significant part of the therapeutic benefit of interferon-alpha (IFN-alpha) therapy in malignant diseases and in chronic viral infections is assumed to result from activation of lymphocytes with natural killer (NK) and T cell phenotype. In tumor tissue and in chronically infected tissue, the function and viability of these lymphocytes are frequently impaired. Mononuclear phagocyte (MP)-derived reactive oxygen species (ROS) have been proposed to contribute to the lymphocyte suppression in these tissues. Here, we report that three types of human cytotoxic lymphocytes of relevance to immunoactivation by IFN-alpha, CD3epsilon+/8+/56- T cells, CD3epsilon-/56+ NK cells, and CD3epsilon+/56+ NK/T cells became anergic to IFN-alpha induction of the cell-surface activation marker CD69 after exposure to autologous MPs in vitro. In addition to their incapacity to express CD69, cytotoxic lymphocytes acquired features characteristic of apoptosis after incubation with MPs. The lymphocyte apoptosis and nonresponsiveness to IFN-alpha were prevented by two inhibitors of reduced nicotinamide adenine dinucleotide phosphate oxidase-dependent formation of ROS in MPs, histamine dihydrochloride and diphenylene ionodonium, as well as by catalase, a scavenger of ROS. We conclude that MP-derived ROS may negatively affect IFN-alpha-induced immunostimulation and propose that ROS inhibitors or scavengers may be useful to improve lymphocyte activation during treatment with IFN-alpha.
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| 6. |
- Hou, Lianhai, et al.
(författare)
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A middle Eocene shorebird from China
- 2002
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Ingår i: The Condor. - 0010-5422 .- 1938-5129. ; 104, s. 896-899
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Tidskriftsartikel (refereegranskat)abstract
- We describe a new species of shorebird, tentatively referred to the family Charadriidae, from the Huadian Formation (Middle Eocene) in Jilin Province, China. In general morphology the specimen closely matches that of an extant charadriid, and correspondsin size to the Killdeer (Charadrius vociferus). If correctly identified this is the oldest record of the Charadriidae. The Middle Eocene paleoenvironment of the Huadian region is thought to have resembled a subtropical swamp.
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| 7. |
- Johansson, Ulf S, et al.
(författare)
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Basal phylogeny of the Tyrannoidea based on comparisons of cytochrome b and exons of nuclear c-myc and RAG-1 genes
- 2002
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Ingår i: The AUK. - 0004-8038 .- 1938-4254. ; 119:4, s. 984-995
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Tidskriftsartikel (refereegranskat)abstract
- The outlines of the phylogenetic relationships within the New World suboscine clade Tyrannoidea were investigated on the basis of nucleotide sequence data from two nuclear genes (c-myc and RAG-1) and one mitochondrial gene (cytochrome b), totaling over 2,400 bp. Representatives of the major tyrannoid lineages were sequenced, including Pachyramphus, Schiffornis, Tityra, and Oxyruncus. The data set with the three genes combined was analyzed under both the parsimony and maximum-likelihood criteria and under different character weighting schemes. The analyses resulted in similar topologies that differed only in poorly supported nodes. The three manakins (Pipra, Manacus, and Chiroxiphia) included in this study were found to be monophyletic, whereas Schiffornis—sometimes also considered to be a manakin—did not group with the manakins, but occurred with Pachyramphus and Tityra in the clade Tityrinae. The two clades Pipromorphinae and Tyranninae are also strongly supported in this analysis and appear as sister groups, thus supporting the monophyly of the tyrant flycatcher assemblage. Phytotoma was placed with the only cotingid species included in this analysis, whereas the position of Oxyruncus was unresolved.
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| 8. |
- Nygård, Louise, et al.
(författare)
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Managing changes in everyday occupations: the experience of persons with Alzheimer's disease.
- 2002
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Ingår i: OTJR (Thorofare, N.J.). - : SAGE Publications. - 1539-4492 .- 1938-2383. ; 22:2, s. 70-81
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to uncover how people with dementia respond to the problems and changes they experience in everyday occupations. Seven participants with dementia were included. Data were collected by means of repeated interviews and observations that focused on the person's experiences of competence and management in everyday occupations. The analysis was carried out from within a phenomenological perspective and resulted in a structure describing management strategies. It was concluded that the participants used a wide variety of strategies. Some strategies were directed toward managing the altered conditions caused by the disease while others served the purpose of responding to the occupational problems of everyday life. The latter strategies were of three types based mainly on environment, habituation, and cognition. Overall, the implicit and explicit cognitive awareness underpinning many strategies seems to call for great caution when assuming that people with dementia soon lose their awareness of disability.
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| 9. |
- Samuelsson, Kersti, 1953-, et al.
(författare)
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The effect of rear-wheel position on seating ergonomics and mobility efficiency in wheelchair users with spinal cord injuries : A pilot study
- 2004
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Ingår i: Journal of rehabilitation research and development. - 0748-7711 .- 1938-1352. ; 41:1, s. 65-74
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Tidskriftsartikel (refereegranskat)abstract
- This study analyzed the effect of rear-wheel position on seating comfort and mobility efficiency. Twelve randomly selected paraplegic wheelchair users participated in the study. Wheelchairs were tested in two rear-wheel positions while the users operated the wheelchair on a treadmill and while they worked on a computer. Propulsion efficiency, seating comfort, and propulsion qualities were registered at different loads during the treadmill session. During the computer session, pelvic position, estimated seating comfort, and estimated activity performance were measured. The change in rear-wheel position affected wheelchair ergonomics with respect to weight distribution (p < 0.0001) and seat inclination angle (position I = 5° and position II = 12°). These changes had a significant effect on push frequency (p < 0.05) and stroke angle (p < 0.05) during wheelchair propulsion. We found no consistent effect on mechanical efficiency, estimated exertion, breathlessness, seating comfort, estimated propulsion qualities, pelvic position, or activity performance.
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