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- Jokiranta, T S, et al.
(författare)
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Complement C3b interactions studied with surface plasmon resonance technique
- 2001
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Ingår i: International Immunopharmacology. - 1567-5769 .- 1878-1705. ; 1:3, s. 495-506
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Tidskriftsartikel (refereegranskat)abstract
- The surface plasmon resonance (SPR) phenomenon is utilized in a number of new real time biosensors. In this study, we have used this technique to study interactions between the central complement component C3b and its multiple ligands by using the Biacore equipment. The SPR technique is particularly suitable for analysis of the alternative complement pathway (AP) because the inherent nature of the latter is to amplify deposition of C3b on various surfaces. C3b was coupled onto the sensor surface and the coupling efficiency was compared under various conditions on both polystyrene and carboxymethylated dextran surfaces. After enzymatic C3b coupling or standard amine C3b coupling, we analyzed and compared the binding of four C3b ligands to the surface: factor B, factor H, C5 and the soluble complement receptor 1 (sCR1, CD35). Binding of each ligand to C3b was detected when C3b had been coupled either enzymatically or using the amine coupling, but the half-lives of the interactions were found to vary depending on the coupling procedure. Factor H binds to C3b via three interaction sites. The target sites are exposed on the C3b, C3c and C3d fragments of C3, respectively. Therefore, we also tested by using the Biacore whether factor B, C5 and sCR1 bind to C3c and/or C3d. It was found that factor B bound to C3d, but not to C3c. On the other hand, both C5 and sCR1 bound to C3c, but not to C3d. In conclusion, this study shows that SPR is a powerful tool in analyzing and mapping the interactions of C3b with its multiple ligands.
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- Kowal, Marta, et al.
(författare)
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Reasons for Facebook Usage : Data From 46 Countries
- 2020
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Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Seventy-nine percent of internet users use Facebook, and on average they access Facebook eight times a day (Greenwood et al., 2016). To put these numbers into perspective, according to Clement (2019), around 30% of the world's population uses this Online Social Network (OSN) site.Despite the constantly growing body of academic research on Facebook (Chou et al., 2009; Back et al., 2010; Kaplan and Haenlein, 2010; McAndrew and Jeong, 2012; Wilson et al., 2012; Krasnova et al., 2017), there remains limited research regarding the motivation behind Facebook use across different cultures. Our main goal was to collect data from a large cross-cultural sample of Facebook users to examine the roles of sex, age, and, most importantly, cultural differences underlying Facebook use.
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- Hepojoki, J, et al.
(författare)
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Acute hantavirus infection induces galectin-3-binding protein
- 2014
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Ingår i: The Journal of general virology. - : Microbiology Society. - 1465-2099 .- 0022-1317. ; 95:Pt 11, s. 2356-2364
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Tidskriftsartikel (refereegranskat)abstract
- Hantaviruses are zoonotic viruses that cause life-threatening diseases when transmitted to humans. Severe hantavirus infection is manifested by impairment of renal function, pulmonary oedema and capillary leakage. Both innate and adaptive immune responses contribute to the pathogenesis, but the underlying mechanisms are not fully understood. Here, we showed that galectin-3-binding protein (Gal-3BP) was upregulated as a result of hantavirus infection bothin vitroandin vivo. Gal-3BP is a secreted glycoprotein found in human serum, and increased Gal-3BP levels have been reported in chronic viral infections and in several types of cancer. Ourin vitroexperiments showed that, whilst Vero E6 cells (an African green monkey kidney cell line) constitutively expressed and secreted Gal-3BP, this protein was detected in primary human cells only as a result of hantavirus infection. Analysis of Gal-3BP levels in serum samples of cynomolgus macaques infected experimentally with hantavirus indicated that hantavirus infection induced Gal-3BP alsoin vivo. Finally, analysis of plasma samples collected from patients hospitalized because of acute hantavirus infection showed higher Gal-3BP levels during the acute than the convalescent phase. Furthermore, the Gal-3BP levels in patients with haemorrhagic fever with renal syndrome correlated with increased complement activation and with clinical variables reflecting the severity of acute hantavirus infection.
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| 7. |
- Jarva, H, et al.
(författare)
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Binding of the complement inhibitor C4bp to serogroup B Neisseria meningitidis
- 2005
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Ingår i: Journal of Immunology. - 1550-6606. ; 174:10, s. 6299-6307
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Tidskriftsartikel (refereegranskat)abstract
- Neisseria meningitidis (meningococcus) is an important cause of meningitis and sepsis. Currently, there is no effective vaccine against serogroup B meningococcal infection. Host defense against neisseriae requires the complement system (C) as indicated by the fact that individuals deficient in properdin or late C components (C6-9) have an increased susceptibility to recurrent neisserial infections. Because the classical pathway (CP) is required to initiate efficient complement activation on neisseriae, meningococci should be able to evade it to cause disease. To test this hypothesis, we studied the interactions of meningococci with the major CP inhibitor Cob-binding protein (C4bp). We tested C4bp binding to wild-type group B meningococcus strain (H44/76) and to 11 isogenic mutants thereof that differed in capsule expression, lipo-oligosaccharide sialylation, and/or expression of either porin (Por) A or PorB3. All strains expressing PorA bound radiolabeled C46p, whereas the strains lacking PorA bound significantly less C4bp. Increased binding was observed under hypotonic conditions. Deleting PorB3 did not influence C4bp binding, but the presence of polysialic acid capsule reduced C4bp binding by 50%. Bound C4bp remained functionally active in that it promoted the inactivation of Cob by factor I. PorA-expressing strains were also more resistant to C lysis than PorA-negative strains in a serum bactericidal assay. Binding of C4bp thus helps Neisseria meningitidis to escape CP complement activation.
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