| 1. |
- Sjögren, M., et al.
(författare)
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Antifouling activity of brominated cyclopeptides from the marine sponge Geodia barretti
- 2004
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Ingår i: Journal of Natural Products. - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 67:3, s. 368-372
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we show the potent antifouling effects of two compounds, barettin (cyclo[(6-bromo-8-entryptophan)arginine]) (1), isolated as a Z/E mixture (87/13), and 8,9-dihydrobarettin (cyclo[(6-bromotryptophan)arginine]) (2), isolated from the marine sponge Geodia barretti. The compounds were isolated guided by their ability to inhibit the settlement of cyprid larvae of the barnacle Balanus improvisus, and their structures were determined by means of mass spectrometry, NMR, and quantitative amino acid analysis. The activities of these brominated diketopiperazine-like cyclic dipeptides are in the range of antifouling agents in use today, as shown by their EC50 values of 0.9 and 7.9 muM, respectively. However, contrary to today's antifouling agents, the effects of barettin and 8,9-dihydrobarettin are nontoxic and reversible. A small set of synthetic analogues, including L-arginine, L-tryptophan, 5-bromo-D,L-tryptophan, 6-bromo-D,L-tryptophan, and 6-fluoro-D,L-tryptophan, were tested for possible structure-activity relationships. None of these compounds showed any effect at a concentration of 10 muM. We hypothesize that the isolated compounds are part of the sponge's chemical defense to deter fouling organisms. This theory is supported by the fact that barettin is found in water exposed to living specimens of G. barretti in concentrations that completely inhibit barnacles from settling.
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| 6. |
- Elmroth, Kerstin, 1970, et al.
(författare)
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Chromatin- and temperature-dependent modulation of radiation-induced double-strand breaks
- 2003
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Ingår i: International Journal of Radiation Biology. - : Informa UK Limited. - 0955-3002 .- 1362-3095. ; 79:10, s. 809-816
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To investigate the influence of chromatin organization and scavenging capacity in relation to irradiation temperature on the induction of double-strand breaks (DSB) in structures derived from human diploid fibroblasts. Materials and methods: Agarose plugs with different chromatin structures (intact cells±wortmannin, permeabilized cells with condensed chromatin, nucleoids and DNA) were prepared and irradiated with X-rays at 2 or 37°C and lysed using two different lysis protocols (new ice-cold lysis or standard lysis at 37°C). Induction of DSB was determined by constant-field gel electrophoresis. Results: The dose-modifying factor (DMFtemp) for irradiation at 37 compared with 2°C was 0.92 in intact cells (i.e. more DSB induced at 2°C), but gradually increased to 1.5 in permeabilized cells, 2.2 in nucleoids and 2.6 in naked DNA, suggesting a role of chromatin organization for temperature modulation of DNA damage. In addition, DMFtemp was influenced by the presence of 0.1 M DMSO or 30 mM glutathione, but not by post-irradiation temperature. Conclusion: The protective effect of low temperature was correlated to the indirect effects of ionizing radiation and was not dependent on post-irradiation temperature. Reasons for a dose modifying factor <1 in intact cells are discussed.
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| 7. |
- Bergman, Mats, et al.
(författare)
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The relative importance of actual and potential competition: Empirical evidence from the pharmaceuticals market
- 2003
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Ingår i: Journal of industrial economics. - : Wiley. - 0022-1821 .- 1467-6451. ; 51, s. 455-467
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Tidskriftsartikel (refereegranskat)abstract
- We study actual and potential competition and other factors that determine price paths of brand-name drugs in the Swedish pharmaceuticals market. The results indicate that the price of the incumbent product is lowered by potential competition, entry of (additional) generics, and the introduction of a so-called reference-price system. We also identify a 'ratchet' effect, through which price regulation makes entry-deterring limit-pricing credible.
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| 8. |
- Björnsson, Gunnar, 1969-, et al.
(författare)
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Argumentationsanalys : Färdigheter för kritiskt tänkande
- 2009. - 2
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Ny reviderad utgåva.Att tänka kritiskt är att självständigt ta ställning till rimligheten i påståenden och argument. Det är en ovärderlig förmåga när vi ställs inför frågor där svaren är många och motstridiga och argumentationen pekar i olika riktningar. I sådana situationer kan det vara svårt att skaffa sig överblick över argumenten, ta ställning till deras styrka och göra en samlad bedömning av alternativen. Lyckligtvis är detta svårigheter som går att hantera med just sådana verktyg som Argumentationsanalys erbjuder. Genom att använda dem förbättrar vi vår förmåga att både identifiera argument i text och tal och bedöma deras beviskraft. Den som själv behöver skriva en argumenterande text eller göra ett argumenterande framförande har dessutom god hjälp av bokens metod att åskådliggöra hur olika argument i en viss fråga förhåller sig till varandra. Argumentationsanalys är en teoretisk och praktisk handledning med övningar. Boken riktar sig till studenter i humanistiska och samhällsvetenskapliga ämnen, men också till alla andra som konfronteras med komplicerade argumentationer.
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- Håkansson, Maria, et al.
(författare)
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Facilitating Mobile Music Sharing and Social Interaction with Push!Music
- 2007
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Ingår i: Proceedings of the 40th Hawaii International Conference on System Sciences. - Los Alamitos, Calif. : IEEE Computer Society Washington. - 1530-1605. - 0769527558 ; , s. 87-
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Konferensbidrag (refereegranskat)abstract
- Push!Music is a novel mobile music listening and sharing system, where users automatically receive songs that have autonomously recommended themselves from nearby players depending on similar listening behaviour and music history. Push!Music also enables users to wirelessly send songs between each other as personal recommendations. We conducted a two-week preliminary user study of Push!Music, where a group of five friends used the application in their everyday life. We learned for example that the shared music in Push!Music became a start for social interaction and that received songs in general were highly appreciated and could be looked upon as 'treats'.
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| 10. |
- Elmroth, Kerstin, 1970, et al.
(författare)
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Cleavage of cellular DNA by calicheamicin γ1
- 2003
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Ingår i: DNA Repair. - 1568-7864 .- 1568-7856. ; 2:4, s. 363-374
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Tidskriftsartikel (refereegranskat)abstract
- It is assumed that the efficient antitumor activity of calicheamicin γ1 is mediated by its ability to introduce DNA double-strand breaks in cellular DNA. To test this assumption we have compared calicheamicin γ1-mediated cleavage of cellular DNA and purified plasmid DNA. Cleavage of purified plasmid DNA was not inhibited by excess tRNA or protein indicating that calicheamicin γ1 specifically targets DNA. Cleavage of plasmid DNA was not affected by incubation temperature. In contrast, cleavage of cellular DNA was 45-fold less efficient at 0°C as compared to 37° due to poor cell permeability at low temperatures. The ratio of DNA double-strand breaks (DSB) to single-stranded breaks (SSB) in cellular DNA was 1:3, close to the 1:2 ratio observed when calicheamicin γ1 cleaved purified plasmid DNA. DNA strand breaks introduced by calicheamicin γ1 were evenly distributed in the cell population as measured by the comet assay. Calicheamicin γ1-induced DSBs were repaired slowly but completely and resulted in high levels of H2AX phosphorylation and efficient cell cycle arrest. In addition, the DSB-repair deficient cell line Mo59J was hyper sensitive to calicheamicin γ. The data indicate that DSBs is the crucial damage after calicheamicin γ1 and that calicheamicin γ1-induced DSBs are recognized normally. The high DSB:SSB ratio, specificity for DNA and the even damage distribution makes calicheamicin γ1 a superior drug for studies of the DSB-response and emphasizes its usefulness in treatment of malignant disease.
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