| 1. |
- Wöhri, Annemarie, 1976, et al.
(författare)
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A Lipidic-Sponge Phase Screen for Membrane Protein Crystallization
- 2008
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Ingår i: Structure. - : Elsevier BV. - 0969-2126 .- 1878-4186. ; 16:7, s. 1003-1009
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Tidskriftsartikel (refereegranskat)abstract
- A major current deficit in structural biology is the lack of high-resolution structures of eukaryotic membrane proteins, many of which are key drug targets for the treatment of disease. Numerous eukaryotic membrane proteins require specific lipids for their stability and activity, and efforts to crystallize and solve the structures of membrane proteins that do not address the issue of lipids frequently end in failure rather than success. To help address this problem, we have developed a sparse matrix crystallization screen consisting of 48 lipidic-sponge phase conditions. Sponge phases form liquid lipid bilayer environments which are suitable for conventional hanging- and sitting-drop crystallization experiments. Using the sponge phase screen, we obtained crystals of several different membrane proteins from bacterial and eukaryotic sources. We also demonstrate how the screen may be manipulated by incorporating specific lipids such as cholesterol; this modification led to crystals being recovered from a bacterial photosynthetic core complex.
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| 2. |
- Andersson, Gerhard, 1966-, et al.
(författare)
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Cognitive bias via the Internet : A comparison of web-based and standard emotional Stroop tasks in social phobia
- 2006
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Ingår i: Cognitive Behaviour Therapy. - : Informa UK Limited. - 1650-6073 .- 1651-2316. ; 35:1, s. 55-62
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Tidskriftsartikel (refereegranskat)abstract
- There is accumulating evidence to suggest that social phobia is associated with attentional bias for words related to social threat. Information processing in individuals with social phobia (n = 87) was investigated in the present study using 2 versions of the emotional Stroop task. Results from a standard emotional Stroop task indicated delayed colour naming of socially threatening words relative to neutral words, in line with previous research, whereas results from a Web-based emotional Stroop task indicated a facilitation effect, with faster manual indication of colour choice for socially threatening words than for neutral words. Possible explanations for these contrasting findings and issues for further research are discussed. © 2006 Taylor & Francis.
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| 3. |
- Andersson, Magnus, et al.
(författare)
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Structural Dynamics of Light-Driven Proton Pumps
- 2009
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Ingår i: Structure. - : Elsevier BV. - 0969-2126 .- 1878-4186. ; 17:9, s. 1265-1275
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Tidskriftsartikel (refereegranskat)abstract
- Bacteriorhodopsin and proteorhodopsin are simple heptahelical proton pumps containing a retinal chromophore covalently bound to helix G via a protonated Schiff base. Following the absorption of a photon, all-trans retinal is isomerized to a 13-cis conformation, initiating a sequence of conformational changes driving vectorial proton transport. In this study we apply time-resolved wide-angle X-ray scattering to visualize in real time the helical motions associated with proton pumping by bacteriorhodopsin and proteorhodopsin. Our results establish that three conformational states are required to describe their photocycles. Significant motions of the cytoplasmic half of helix F and the extracellular half of helix C are observed prior to the primary proton transfer event, which increase in amplitude following proton transfer. These results both simplify the structural description to emerge from intermediate trapping studies of bacteriorhodopsin and reveal shared dynamical principles for proton pumping.
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| 4. |
- Hassing, Linda, 1967, et al.
(författare)
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Overweight in midlife and risk of dementia: a 40-year follow-up study
- 2009
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Ingår i: International Journal of Obesity. - : Springer. ; 33:8, s. 893-898
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This study examines whether overweight in midlife increases dementia risk later in life. Methods: In 1963 body mass index was assessed in 1152 participants of The Swedish Twin Registry, at the age of 45–65 years. These participants were later screened for dementia in a prospective study with up to 40 years follow-up. A total of 312 participants were diagnosed with dementia. Results: Logistic regression analyses adjusted for demographic factors, smoking and alcohol habits, indicated that men and women categorized as overweight in their midlife had an elevated risk of dementia (OR=1.59; 95% CI: 1.21–2.07, P=0.002), Alzheimer's disease (OR=1.71; 95% CI: 1.24–2.35, P=0.003), and vascular dementia (OR=1.55; 95% CI: 0.98–2.47, P=0.059). Further adjustments for diabetes and vascular diseases did not substantially affect the associations, except for vascular dementia (OR=1.36; 95% CI: 0.82–2.56, P=0.116), reflecting the significance of diabetes and vascular diseases in the etiology of vascular dementia. There was no significant interaction between overweight and APOE alt epsilon4 status, indicating that having both risk factors does not have a multiplicative effect with regard to dementia risk. Conclusions: This study gives further support to the notion that overweight in midlife increases later risk of dementia. The risk is increased for both Alzheimer's disease and vascular dementia, and follows the same pattern for men and women. Keywords: BMI, alzheimer's disease, vascular dementia, dementia, overweight, obesity
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| 5. |
- Johansson, Linda C, 1983, et al.
(författare)
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Membrane protein crystallization from lipidic phases
- 2009
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Ingår i: Current Opinion in Structural Biology. - : Elsevier BV. - 0959-440X .- 1879-033X. ; 19:4, s. 372-378
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Tidskriftsartikel (refereegranskat)abstract
- Membrane protein structural biology is enjoying a steady acceleration in the rate of success. Nevertheless, numerous membrane protein targets are resistant to the traditional approach of directly crystallizing detergent solubilized and purified protein and the 'niche market' of lipidic phase crystallization is emerging as a powerful complement. These approaches, including lipidic cubic phase, lipidic sponge phase, and bicelle crystallization methods, all immerse purified membrane protein within a lipid rich matrix before crystallization. This environment is hypothesized to contribute to the protein's long-term structural stability and thereby favor crystallization. Spectacular recent successes include the high-resolution structures of the beta(2)-adrenergic G-protein-coupled receptor, the A(2A) adenosine G-protein-coupled receptor, and the mitochondrial voltage dependent anion channel. In combination with technical innovations aiming to popularize these methods, lipidic phase crystallization approaches can be expected to deliver an increasing scientific impact as the field develops.
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| 6. |
- Johansson, Linda, 1975-
(författare)
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The Role of Cognitive Processes in Eating Pathology
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Researchers have recently combined clinical and cognitive areas of research in order to investigate the role of cognitive factors in explaining how emotional disorders are developed and maintained. It is believed that biased cognitive processing of emotionally relevant information can greatly affect emotional responses and behaviour where insights into such cognitive processes can have invaluable clinical implications.The present thesis investigates the role of cognitive biases for information related to food and body appearance in individuals with eating disorders (ED) and those with non-clinically eating disorder-related concerns (NED). Are ED characterised by cognitive biases toward such information related to their specific concerns? Are such cognitive biases specific to clinical ED or present also in NED samples? Are cognitive biases operating at both conscious and unconscious levels of cognitive processing?The tasks used to pursue these questions were: the emotional Stroop task, an Internet version of the emotional Stroop, Jacoby’s white noise paradigm and a recognition task. The influence of priming on the emotional Stroop task was also investigated in order to test whether the use of this task could be extended to more complex investigations than selective attention.Results provide support for that cognitive processing of information related to eating and body appearance is biased in individuals with ED. It is, however, unclear whether such biased processing is specific to clinical ED. Findings further suggest that cognitive biases occur primarily at unconscious levels of cognitive processing. Support was also obtained for that the emotional Stroop task is sensitive to priming where initial body perception may be one factor influencing cognitive responses toward negative self referent words following exposure to thin ideal images. Results further suggest that the emotional Stroop task successfully can be administered via the Internet where manipulating task delivery and response mode may increase the sensitivity of this task. Some of the advantages of administering the emotional Stroop task via Internet over traditional methods are access to more heterogeneous samples, more ecologically valid situations, reduced costs and minimisation of demand characteristics.
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| 7. |
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| 8. |
- Sällsten, Gerd, 1952, et al.
(författare)
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Experimental wood smoke exposure in humans
- 2006
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Ingår i: Inhalation Toxicology. - : Informa UK Limited. - 0895-8378 .- 1091-7691. ; 18:11, s. 855-864
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Tidskriftsartikel (refereegranskat)abstract
- Experimental studies are used to evaluate effects of human exposure to diesel exhaust and concentrated ambient particles. This article describes a system for studying exposure of humans to wood smoke. Wood smoke was generated using a wood stove placed outside an exposure chamber that can hold at least 10 subjects. A partial flow of the generated wood smoke from the stove was mixed with filtered indoor air. Personal and stationary measurements were performed of PM2.5 and PM1 mass concentrations and various volatile organic compounds (VOCs): 1,3-butadiene, benzene, and aldehydes. In addition, particulate matter ( PM) mass, number concentrations, and size distributions of particles (0.007 - 6.7 mu m), as well as nitrous oxides, CO2, and CO, were measured online. Filters were analyzed for trace elements and black smoke. Polycyclic aromatic compounds, toluene, and xylenes were determined in stationary samples. Results of the first experiment showed no differences between personal and stationary measurements for particles or VOCs. Consequently, stationary measurements can be used to predict personal exposure. All PM mass ( about 250 mu g/m(3)) was in the PM1 fraction. Subjective symptoms were generally weak, while clear objective signs were found, for example, in biomarkers of inflammation. With careful control of the combustion process, relatively constant mass and number concentrations were obtained over each exposure session. By varying the combustion and dilution of the wood smoke, different exposure scenarios can be achieved and thus, knowledge about which of the properties of particles and gaseous compounds are crucial for the effects.
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| 9. |
- Wöhri, Annemarie, 1976, et al.
(författare)
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Lipidic sponge phase crystal structure of a photosynthetic reaction center reveals lipids on the protein surface.
- 2009
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 1520-4995 .- 0006-2960. ; 48:41, s. 9831-8
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Tidskriftsartikel (refereegranskat)abstract
- Membrane proteins are embedded in a lipid bilayer and maintain strong interactions with lipid molecules. Tightly bound lipids are responsible for vertical positioning and integration of proteins in the membrane and for assembly of multisubunit complexes and occasionally act as substrates. In this work we present the lipidic sponge phase crystal structure of the reaction center from Blastochloris viridis to 1.86 A, which reveals lipid molecules interacting with the protein surface. A diacylglycerol molecule is bound, through a thioether bond, to the N-terminus of the tetraheme cytochrome c subunit. From the electron density recovered at the Q(B) site and the observed change in recombination kinetics in lipidic sponge phase-grown crystals, the mobile ubiquinone appears to be displaced by a monoolein molecule. A 36 A long electron density feature is observed at the interface of transmembrane helices belonging to the H- and M-subunits, probably arising from an unidentified lipid.
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