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- Porcu, E, et al.
(författare)
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Mendelian randomization integrating GWAS and eQTL data reveals genetic determinants of complex and clinical traits
- 2019
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10:1, s. 3300-
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Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association studies (GWAS) have identified thousands of variants associated with complex traits, but their biological interpretation often remains unclear. Most of these variants overlap with expression QTLs, indicating their potential involvement in regulation of gene expression. Here, we propose a transcriptome-wide summary statistics-based Mendelian Randomization approach (TWMR) that uses multiple SNPs as instruments and multiple gene expression traits as exposures, simultaneously. Applied to 43 human phenotypes, it uncovers 3,913 putatively causal gene–trait associations, 36% of which have no genome-wide significant SNP nearby in previous GWAS. Using independent association summary statistics, we find that the majority of these loci were missed by GWAS due to power issues. Noteworthy among these links is educational attainment-associated BSCL2, known to carry mutations leading to a Mendelian form of encephalopathy. We also find pleiotropic causal effects suggestive of mechanistic connections. TWMR better accounts for pleiotropy and has the potential to identify biological mechanisms underlying complex traits.
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| 4. |
- Sjöström, B, et al.
(författare)
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A method for the preparation of submicron particles of sparingly water-soluble drugs by precipitation in oil-in-water emulsions. II. Influence of the emulsifier, the solvent, and the drug substance
- 1993
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Ingår i: Journal of Pharmaceutical Sciences. - 0022-3549 .- 1520-6017. ; 82, s. 584-589
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Tidskriftsartikel (refereegranskat)abstract
- Small particles of two steroids; cholesteryl acetate and b-sitosterol, have been prepared by the following technique: The steroid was dissolved in an organic solvent, which was emulsified in water in the presence of sur--factant, thus giving a water continuous emulsion. As the organic solvent was evaporated the steroid precipitated. One particle was found to form in each emulsion droplet. Particle sizes down to 25 nm were obtained by this method. Particles were prepared from emulsions containing different organic solvents and surfactants and the effect on the size and the colloi--dal stability of the particles were examined. It was found that the final particle suspension is relatively stable provided the initial emulsion is stable. Furthermore, there is a close correlation between the initial emul--sion droplet size and the final particle size. The particle size, therefore, can be varied in the same manner as the size of emulsion droplets, e.g. by changing the emulsification process parameters, the amount and choice of surfactant and the oil/water ratio. Finally, the particle size depends on the choice of solvent and only slightly on the concentration of drug in the oil phase of the emulsion.
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- Branduardi-Raymont, G., et al.
(författare)
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Exploring solar-terrestrial interactions via multiple imaging observers
- 2022
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Ingår i: Experimental astronomy. - : Springer Nature. - 0922-6435 .- 1572-9508. ; 54:2-3, s. 361-390
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Tidskriftsartikel (refereegranskat)abstract
- How does solar wind energy flow through the Earth's magnetosphere, how is it converted and distributed? is the question we want to address. We need to understand how geomagnetic storms and substorms start and grow, not just as a matter of scientific curiosity, but to address a clear and pressing practical problem: space weather, which can influence the performance and reliability of our technological systems, in space and on the ground, and can endanger human life and health. Much knowledge has already been acquired over the past decades, particularly by making use of multiple spacecraft measuring conditions in situ, but the infant stage of space weather forecasting demonstrates that we still have a vast amount of learning to do. A novel global approach is now being taken by a number of space imaging missions which are under development and the first tantalising results of their exploration will be available in the next decade. In this White Paper, submitted to ESA in response to the Voyage 2050 Call, we propose the next step in the quest for a complete understanding of how the Sun controls the Earth's plasma environment: a tomographic imaging approach comprising two spacecraft in highly inclined polar orbits, enabling global imaging of magnetopause and cusps in soft X-rays, of auroral regions in FUV, of plasmasphere and ring current in EUV and ENA (Energetic Neutral Atoms), alongside in situ measurements. Such a mission, encompassing the variety of physical processes determining the conditions of geospace, will be crucial on the way to achieving scientific closure on the question of solar-terrestrial interactions.
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| 7. |
- Folmer, B, et al.
(författare)
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The effect of surfactant-polymer association on the stabilities of foams and thin films: sodium dodecyl sulfate and poly(vinyl pyrrolidone)
- 2000
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Ingår i: Langmuir. - 0743-7463 .- 1520-5827. ; 16, s. 5987-5992
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Tidskriftsartikel (refereegranskat)abstract
- The foaming behaviour of the anionic surfactant Sodium Dodecyl Sulphate (SDS) has been studied in the presence and in the absence of the nonionic polymer Poly Vinyl Pyrrolidone (PVP). A current model of surfactant - polymer aggregation in bulk and at the air-water interface is related to the foam and thin film stability. Tensiometry, foaming tests and a thin film balance are used to obtain this relationship. It is found that at very low surfactant concentrations, where the surfactants are present as unimers in the bulk solution, there is association between surfactants and polymer at the liquid/air surface, giving an increased foam and thin film stability as compared to the same surfactant concentration but without polymer. As the surfactants and polymers associate in the bulk solution there is desorption of surfactants and polymers from the surface rendering a decrease in foam and thin film stability. At higher surfactant concentrations the bulk viscosity is significantly increased due to the presence of both micelles and saturated micelle-polymer complexes. Also the surfactant surface coverage at the liquid/air surface has reached its maximum value and is similar to the SDS solution above the CMC when no polymer is present. Both the increased surface viscosity and the increased bulk viscosity contribute to the observed foam and film stability. In the thin film studies several stratification steps are observed probably due to micelles, which are being pushed out of the film.
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| 8. |
- Sjöström, B, et al.
(författare)
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A method for the preparation of submicron particles of sparingly water-soluble drugs by precipitation in oil-in-water emulsions. I. Influence of emulsification and surfactant concentration
- 1993
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Ingår i: Journal of Pharmaceutical Sciences. - 0022-3549 .- 1520-6017. ; 82, s. 579-583
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a method for the synthesis of small particles of poorly water soluble drug substances using emulsions. In the first place, the drug is dissolved in an organic solvent and a water soluble surfactant is dissolved in water. Secondly, these two solutions are mixed to form an emulsion, where the organic solution is emulsified into small droplets in the aqueous phase. The action of the surfactant is partly to decrease the interfacial tension between the water and the organic solution, thus increasing the ease of emulsification, and partly to stabilize the droplets formed against aggregation, or coalescence. The final step in the process is to remove the organic solvent by evaporation in doing which the drug precipitates and one particle is formed in each droplet. If the surfactant is sufficiently effective in stabilizing the particles formed against coagula--tion, we have a suspension of small spherical drug particles. In this paper we use a model system consisting of cholesteryl acetate and toluene. Particles down to 50 nm were obtained by this method. The sizes of the particles were found to be dependent on the surfactant concentration and the emulsification energy.
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| 10. |
- Andersson, M., et al.
(författare)
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A New Class of Labile Surfactants that Break Down to Non-surface Active Products upon Heating or after a Pre-set Time, without the Need for a pH Change
- 2007
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Ingår i: Tenside Surfactants Detergents. - : Walter de Gruyter GmbH. - 0932-3414 .- 2195-8564. ; 44:6, s. 366-372
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Tidskriftsartikel (refereegranskat)abstract
- A new class of labile surfactants that break down at a controllable rate without the need for a change in pH will be presented. The invention has been patented by YKI Institute for Surface Chemistry, and is based on use of β-keto acids or their salts as surface-active compounds. These surfactants spontaneously break down through decarboxylation, to form an oil-like ketone and CO 2/HCO 3 -/CO 32 - depending on pH. The rate of breakdown can be controlled within a wide range by temperature or by certain additives, but, unlike most cleavable surfactants, a change in pH is not needed. Furthermore the surfactants can be conveniently activated from a stabile precursor just before use, and one (of many possible) precursors of this kind is already available on the industrial scale in the form of a wellknown chemical that is FDA-approved in other, non-surfactant, applications. The compound in question, alkyl ketene dimer (AKD), is produced in large scale by a number of large chemical producers today, and used for hydrophobization of paper. The present article gives an overview of the surfactant chemistry, with focus on recent studies of the kinetics of activation of the surfactant precursor and breakdown kinetics of the labile surfactant at different conditions. Furthermore, possible industrial applications of the surfactant will be discussed, with one example taken from a recent feasibility study performed within the car washing area. © Carl Hanser Publisher.
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