| 1. |
- Andersson, Magnus, et al.
(författare)
-
Vortex liquid properties in optimally doped and oxygen-deficient YBa2Cu3O7-delta single crystals
- 2000
-
Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 332:1-4, s. 86-92
-
Tidskriftsartikel (refereegranskat)abstract
- The electrical anisotropy, gamma = (m(c)/m(ab))(1/2), can easily be varied by changing the oxygen content in single crystals of YBa2Cu3O7-delta (YBCO); thus making this system useful as a test system For vortex dynamics in high-temperature superconductors (HTSC). Here, some recent results are reviewed. Measurements of the c-axis resistivity with the magnetic field B II ab-plane is shown to be a powerful tool in studying vortex velocity correlations both parallel and perpendicular to the applied field. In optimally doped crystals, we iind evidence that the in-plane vortex lattice melts at T-m into a disentangled vortex liquid, which looses its correlation along the c-axis at a higher temperature T-br > T-m. For weakly disordered crystals and magnetic fields B \\ c-axis, a relation between the vortex glass line and the magnetic field dependence of the characteristic energy, U*, in the pinned vortex liquid is proposed. This approach is shown to give support to our idea of describing the vortex glass resistivity in the liquid regime by a modified glass correlation Length, xi(g) = xi(0)\k(B)T/U-0 - 1\(-nu) which depends on the average pinning energy, Lr,, in the system [A. Rydh, O. Rapp, M. Andersson, Phys. Rev. Lett. 83 (1999) 1850].
|
|
| 2. |
- Carlsson, Katrin, et al.
(författare)
-
Fear and the Amygdala : Manipulation of Awareness Generates Differential Cerebral Responses to Phobic and Fear-Relevant (but Nonfeared) Stimuli
- 2004
-
Ingår i: Emotion. - : American Psychological Association (APA). - 1528-3542 .- 1931-1516. ; 4:4, s. 340-353
-
Tidskriftsartikel (refereegranskat)abstract
- Rapid response to danger holds an evolutionary advantage. In this positron emission tomography study, phobics were exposed to masked visual stimuli with timings that either allowed awareness or not of either phobic, fear-relevant (e.g., spiders to snake phobics), or neutral images. When the timing did not permit awareness, the amygdala responded to both phobic and fear-relevant stimuli. With time for more elaborate processing, phobic stimuli resulted in an addition of an affective processing network to the amygdala activity, whereas no activity was found in response to fear-relevant stimuli. Also, right prefrontal areas appeared deactivated, comparing aware phobic and fear-relevant conditions. Thus, a shift from top-down control to an affectively driven system optimized for speed was observed in phobic relative to fear-relevant aware processing. (PsycINFO Database Record (c) 2006 APA, all rights reserved) (journal abstract)
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Dolby, Viveka, et al.
(författare)
-
Effects of pH, salt and time on ligand binding properties of overexpressed melanocortin 4 receptor.
- 2004
-
Ingår i: Journal of Biochemical and Biophysical Methods. - : Elsevier BV. - 0165-022X. ; 58:3, s. 195-205
-
Tidskriftsartikel (refereegranskat)abstract
- The G-protein coupled melanocortin 4 receptor (MC4r) plays an important role in the energy metabolism. We overexpressed the MC4r in CHO cells and performed characterisation studies on the cell membranes to determine functional stability and ligand binding properties of the receptor. The affinity for the ligands [Nle4, Image-Phe7]-αMSH and MTII was lost below pH 6 but could be restored by returning to physiological pH. Increasing NaCl concentration up to 1 M had little influence on the binding of either ligand. At neutral pH, physiological salt concentration and 4 °C the ligand affinity of the receptor was stable for up to 6 days. These findings will facilitate design of purification methods for the receptor.
|
|
| 6. |
- Gottschalk, Ingo, et al.
(författare)
-
Conversion between two cytochalasin B-binding states of the human GLUT1 glucose transporter
- 2000
-
Ingår i: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 267:23, s. 6875-6882
-
Tidskriftsartikel (refereegranskat)abstract
- Two cytochalasin B-binding states of the human red blood cell facilitative glucose transporter GLUT1 were studied, one exhibiting one cytochalasin B-binding site on every second GLUT1 monomer (state 1) and the other showing one site per monomer (state 2). Quantitative affinity chromatography of cytochalasin B was performed on (a) biotinylated red blood cells, (b) cytoskeleton-depleted red blood cell membrane vesicles, and (c) GLUT1 proteoliposomes. The cells were adsorbed on streptavidin-derivatized gel beads, and the vesicles and proteoliposomes entrapped in dextran-grafted agarose gel beads. Cytochalasin B binding to free vesicles and proteoliposomes was analyzed by Hummel and Dreyer size-exclusion chromatography and ultracentrifugation. Analysis of the biotinylated cells indicated an equilibrium between the two GLUT1 states. GLUT1 in free membrane vesicles attained state 2, but was converted into state 1 on entrapment of the vesicles. Purification of GLUT1 in the presence of non-ionic detergent followed by reconstitution produced GLUT1 in state 1. This state was maintained after entrapment of the proteoliposomes. Finally, GLUT1 showed slightly higher affinity for cytochalasin B in state 1 than in state 2. In summary, the cytochalasin B-binding state of GLUT1 seemed to be affected by (a) biotinylation of the cell surface, (b) removal of the cytoskeleton at high pH and low ionic strength, (c) interaction between the dextran-grafted agarose gel matrix and the membrane vesicles, and (d) reconstitution to form proteoliposomes.
|
|
| 7. |
- Gottschalk, Ingo, et al.
(författare)
-
Immobilised biomembrane affinity chromatography for binding studies of membrane proteins
- 2002
-
Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 768:1, s. 31-40
-
Forskningsöversikt (refereegranskat)abstract
- Analyses of specific interactions between solutes and a membrane protein can serve to characterize the protein. Frontal affinity chromatography of an interactant on a column containing the membrane protein immobilized in a lipid environment is a simple and robust approach for series of experiments with particular protein molecules. Regression analysis of the retention volumes at a series of interactant concentrations shows the affinity of the protein for the interactant and the amount of active binding sites. The higher the affinity, the fewer sites are required to give sufficient retention. Competition experiments provide the affinities of even weakly binding solutes and the non-specific retention of the primary interactant. Hummel and Dreyer size-exclusion chromatography allows complementary analyses of non-immobilized membrane materials. Analyses of the human facilitative glucose transporter GLUT1 by use of the inhibitor cytochalasin B (radioactively labeled) and the competitive substrate D-glucose (non-labeled) showed that GLUT1 interconverted between two states, exhibiting one or two cytochalasin B-binding sites per two GLUTI monomers, dependent on the membrane composition and environment. Similar analyses of a nucleoside transporter, a photosynthetic reaction center, nicotinic acetylcholine receptors and a P-glycoprotein, alternative techniques, and immobilized-liposome chromatographic approaches are presented briefly.
|
|
| 8. |
- Lundqvist, Andreas
(författare)
-
Dendritic cells in immune and gene therapy against cancer
- 2003
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dendritic cells (DC) are extensively used for vaccine therapy due to their superior T cell stimulatory capacity. However, the modest therapeutic effects reported by most clinical trials using DC, together with the rapid developing field of DC biology suggests important considerations for improvement of the clinical outcome. The general aim of this thesis is to develop DC-based cancer vaccines thereby facilitating the translation of such therapeutic approaches to the clinic. An ancillary aim of this study is to better understand the factors that affect the apoptosis of DC particularly during their differentiation from monocyte precursors. Mature DC are effectively resistant to Fas-mediated apoptosis. One of the underlying mechanisms that mediate this resistance is the observed upregulation of Bcl-XL that accompanies DC maturation. These results provide additional support for the use of mature DC as cellular adjuvants since they not only represent a more potent T cell stimulatory population, but also may mediate a more protracted effect due to their resistance to Fas induced apoptosis. The mode of antigen delivery is pivotal to the generation of specific immunity. In this study, a comparison of viral and non-viral gene delivery techniques to human DC derived from peripheral blood precursors or CD34+ stem cells were performed. DC differentiated from both types progenitor cells were receptive to non-viral transfection using mRNA and electroporation. In addition, the number of transfected cells was comparable to what could be achieved by adeno- and retro-viral transduction. These findings encourage the use of non-viral methods for transfection of DC as problem of neutralizing antibodies and prohibitively expensive safety tests associated with viral delivery may limit their use in the clinic. Certain viruses can lead to inhibition or maturation of DC or even induce their apoptosis. Furthermore, the effect of viral transduction on cell physiology and APC activity has not been satisfactorily elucidated. Transduction of monocyte derived-DC using adenovirus (AdV) results in generation of DC that are phenotypically and functionally "activated". Taken together, the transfer of antigenic epitopes at high efficiency to human monocyte-derived DC as well as the DC- activating effects are strong arguments for their clinical application of AdV-transduced DC-based vaccines. The final aspect of the thesis utilizes prostate specific antigen (PSA) as a model tumor antigen for generation of specific T cell response, using DC transfected with different delivery methods. Stimulation with AdV transduced TNFalpha treated DC resulted in the generation of PSA-specific T cells that predominantly produced IL10. However, stimulation with untreated, lipopolysaccharide, or anti-CD40 treated AdV transduced DC resulted in generation of IFNgamma, but not IL-10, producing PSA-specific T cells indicating that the predominant population was Th1 T cells. In conclusion, conventional antigen delivery and DC maturation methods may influence the functional characteristics of the generated DC and may produce T cell populations with aberrant functions, that in certain instances may be counter productive to the anti-tumor immune response desired with vaccination strategies.
|
|
| 9. |
|
|
| 10. |
- Lundqvist, Andreas, et al.
(författare)
-
Dynamic train/track interaction including model for track settlement evolvement
- 2004
-
Ingår i: Vehicle System Dynamics. - 0042-3114 .- 1744-5159. ; 41 (Supplement), s. 667-676
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A ballasted railway track exposed to train traffic will degenerate. Track alignment and track level will deteriorate. Settlements of the track (loss of track level and alignment) require maintenance; the track is lifted and aligned, and new ballast material is injected under the sleepers. This paper presents a computer model by which the dynamic train/track interaction can be simulated and the permanent deformation of the track (i.e. track settlements) can be calculated. The voided sleepers ("hanging" sleepers) phenomenon will also be discussed.
|
|
| 11. |
|
|
| 12. |
|
|
