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Träfflista för sökning "WFRF:(Lindström Tobias) srt2:(2002-2004)"

Sökning: WFRF:(Lindström Tobias) > (2002-2004)

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  • Lindström, Fredrick, et al. (författare)
  • Association of amyloid-β peptide with membrane surfaces monitored by solid state NMR
  • 2002
  • Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 4:22, s. 5524-5530
  • Tidskriftsartikel (refereegranskat)abstract
    • Amyloid-β peptide (Aβ), a key substance in Alzheimers disease (AD), is characterized by its abnormal folding into neurotoxic aggregates. Since Aβ comprises an extracellular and transmembrane domain, some of its neurotoxic actions might be exerted via interactions with neuronal membranes. Wideline and magic angle spinning 14N and 31P NMR have been used in combination with differential scanning calorimetry and circular dichroism spectroscopy to investigate the association between Aβ1–40 peptide and membranes with different electrostatic surface potentials. Calorimetric measurements showed that all membrane systems were in the liquid crystalline state at 308 K. Binding of Aβ1–40 at a 30 1 lipid/peptide ratio to membranes composed of neutral dimyristoyl-phosphatidylcholine (DMPC) and negatively charged dimyristoylphosphatidylglycerol (DMPG) at a 4 : 1 molar ratio is mainly driven electrostatically, reflected in characteristic changes of the isotropic 31P chemical shift values for both lipids. In addition, the average orientation of the choline headgroup of DMPC, with its electric P––N+(CH3)3 dipole, changed directly in response to the reduced negative membrane surface potential. The deviation in tilt angle of the PN vector relative to the membrane surface is manifested in the observed 14N NMR quadrupole splitting and can therefore be described semiquantitatively. Adding Aβ1–40 to membranes with nominal neutral surface charge, but composed of a ternary mixture of DMPC with DMPG and the cationic amphiphile didodecyldimethyl–ammonium bromide (DDAB) at a 3 : 1 : 1 molar ratio revealed surprisingly electrostatic interactions visible in the NMR spectra. Since Aβ1–40 does not bind to neutral DMPC bilayers a model is proposed, in which on a molecular level the charged residues of Aβ1–40 peptide can interact independently with lipid headgroups of various charges in these microscopically heterogeneous systems.
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  • Lindström, Tobias, 1976 (författare)
  • Dynamics of high-angle grain boundary YBCO Josephson junctions
  • 2004
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This thesis describes experimental investigations of properties of high-angle YBa2Cu3O7−δ(YBCO)bicrystal Josephson junctions and SQUIDs fabricated on SrTiO3-substrates. The main focus of theinvestigation has been on the effects of the predominant d-wave symmetry of the superconductingwavefunction in YBCO on transport properties and dynamics.At a high-angle grain-boundary interface between two high-temperature superconductors Andreevstates can form, the current carried by these states hasπ-periodic component which flows in a direc-tion opposite of the usual Josephson current. Asymmetric high-angle grain boundaries also exhibit acritical current which is four orders of magnitude lower than symmetric lower-angle junctions, thiscan be attributed to the node-lobe arrangement of the the superconducting order parameter.High-angle grain-boundary dc-SQUIDs that have been studied which exhibit unusual dynamicssuch as a relative ”shift” of the positions of the positive and negative modulation and a highly non-sinusoidal dependence on the external field. This behavior vanished when moving to very narrowjunctions. These result are explained using a semi-classical model which assumes the presence ofa2ndharmonic in the current-phase relation. Numerical simulations confirm that this model is inqualitative agreement with experimental results.The properties of sub-micron sized junctions have also been studied. These exhibit some un-usual behavior. These junctions have been used to study the tunnelling spectra since the high normalresistance means that it is possible to study energies close to the gap.Finally, some general properties of high-angle Josephson Junctions are discussed. It is arguedthat some seemingly inconsistent experimental results can be explained using a multi-channel modelwhich accounts for the wiggling and faceting of the interface.
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  • Ståleheim, Gunilla, et al. (författare)
  • Odiagnostiserade depressioner finns överallt i vården : Somatisk öppen och sluten vård och primärvård i Uplland screenad
  • 2003
  • Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 100:36, s. 2760-2763
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • En större undersökning av depressionsförekomsten inom somatisk öppen och sluten vård samt inom pri- märvården genomfördes under våren 2002 i Uppland under namnet »Depression screening day«.52 av 267 patienter hade en depressionsdiagnos känd inom rutinsjukvården. I samband med undersökning- en upptäcktes ytterligare 40 patienter som hade en de- pression.En del av de nyupptäckta depressionerna var av lätta- re slag, men knappt 40 procent var av sådan svårig- hetsgrad att de enligt gällande rekommendationer från Läkemedelsverket skulle motivera behandling.Inga signifikanta skillnader i svårighetsgrad förelåg mellan patienter diagnostiserade inom rutinsjukvår- den och patienter diagnostiserade i samband med en screeningundersökning. Det tycks således inte främst vara specifika karakteristika hos de depressiva syndro- men som avgör om patienten diagnostiseras inom ru- tinsjukvården eller inte.
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