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- Löfgren, Ragnhild, et al.
(författare)
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CR3, FcγRIIA and FcγRIIIB induce activation of the respiratory burst in human neutrophils : the role of intracellular Ca2+, phospholipase D and tyrosine phosphorylation
- 1999
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Ingår i: Biochimica et Biophysica Acta. Molecular Cell Research. - 0167-4889 .- 1879-2596. ; 1452:1, s. 46-59
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Tidskriftsartikel (refereegranskat)abstract
- Human neutrophils express two different types of phagocytic receptors, complement receptors (CR) and Fc receptors. In order to characterize the different signaling properties of each receptor we have used non-adherent human neutrophils and investigated CR3, FcγRIIA and FcγRIIIB for their signaling capacity. Selective activation of each receptor was achieved by coupling specific antibodies to heat-killed Staphylococcus aureus particles, Pansorbins, through their Fc moiety. Despite the fact that these particles are not phagocytosed, we show that addition of Pansorbins with anti-CD18 antibodies recognizing CR3 induced prominent signals leading to a respiratory burst. Stimulation with anti-FcγRIIIB Pansorbins induced about half of the response induced by anti-CR3 Pansorbins, whereas anti-FcγRIIA Pansorbins induced an even weaker signal. However, FcγRIIA induced strong phosphorylation of p72syk whereas FcγRIIIB induced only a very weak p72syk phosphorylation. During CR3 stimulation no tyrosine phosphorylation of p72syk was seen. Both phospholipase D and NADPH oxidase activities were dependent on intracellular calcium. This is in contrast to tyrosine phosphorylation of p72syk that occurred even in calcium-depleted cells, indicating that oxygen metabolism does not affect p72syk phosphorylation. Inhibitors of tyrosine phosphorylation blocked the respiratory burst induced by both FcγRIIA and FcγRIIIB as well as CR3. This shows that tyrosine phosphorylation of p72syk is an early signal in the cascade induced by FcγRIIA but not by CR3.
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| 2. |
- Löfgren, Åsa, 1972, et al.
(författare)
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The Phase-Out of Leaded Gasoline in the EU: A Successful Failure?
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The objective of this paper is to analyze in both descriptive and econometric terms the phase-out of leaded gasoline consumption in the EU countries. The phase-out process is characterized by increased consumption of unleaded gasoline. We analyze the importance of price differences, share of catalytic converters, income per capita, and country characteristics in the phase-out process. Since the expected maintenance costs of using unleaded gasoline in cars without catalytic converters compared to the use of leaded gasoline differ insignificantly according to available evidence, and consumers still use leaded gasoline even though unleaded gasoline is cheaper; we interpret this as a lack of reliable information. The results indicate that countries, which have not yet phased out leaded gasoline, should do this by either banning leaded gasoline or by increasing the tax differential between leaded and unleaded gasoline depending on the objective of the social planner.
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