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- Miguel, Maria, et al.
(författare)
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DNA-cationic amphiphile interactions
- 2003
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Ingår i: Colloids and Surfaces a-Physicochemical and Engineering Aspects. ; 228:1-3, s. 43-55
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Tidskriftsartikel (refereegranskat)abstract
- DNA shows strong interactions with cationic cosolutes and these have both biological and technological significance. We outline our research on various mixed system of DNA and cationic amphiphiles including the interaction of DNA with simple cationic surfactants as well as the interaction with catanionic mixtures and positively charged catanionic vesicles. An overview from phase behavior to microstructure will be presented. We will also address DNA compaction and decompaction phenomena in different systems. Finally, simulations on DNA confinement and interaction with cationic polyions are considered. (C) 2003 Published by Elsevier B.V.
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- Candinas, R, et al.
(författare)
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Impact of fusion avoidance on performance of the automatic threshold tracking feature in dual chamber pacemakers: A multicenter prospective randomized study
- 2002
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Ingår i: PACE. - : Wiley. - 1540-8159. ; 25:11, s. 1540-1545
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Tidskriftsartikel (refereegranskat)abstract
- The Autocapture algorithm enables automatic capture verification on a beat-by-beat basis by recognizing the evoked response signal following each pacemaker stimulus. The algorithm intends to increase patient safety while decreasing energy consumption. However, the occurrence of fusion beats, particularly during dual chamber pacing, may limit the energy saving effect of Autocapture. The aim of this multicenter, prospective, randomized study was to evaluate the impact of the Fusion Avoidance (FA) algorithm on the incidence of fusion beats. Thirty-eight patients (mean age 69 +/- 13 years) with intrinsic AV conduction who were implanted with an Affinity DR were studied. After programming a PV/AV delay of 120/190 ms, patients were randomized to FA On or Off. Each group was further randomized with respect to activation of the AutoIntrinsic Conduction Search (AICS) algorithm. The total number of beats, ventricular paced beats, fusion beats, backup pulses, and threshold searches were analyzed from 24-hour Holter recordings. The number of total beats was comparable in both FA groups. The number of total ventricular paced beats, fusion beats, backup pulses, and threshold searches were significantly reduced in the FA On group (% reduction: 68% P < 0.001, 75% P < 0.01, 95% P < 0.01, and 94% P < 0.05, respectively). The number of ventricular paced beats with full capture was significantly reduced when AICS was activated (P < 0.05). In conclusion, the FA algorithm substantially reduces the amount of ventricular paced beats, fusion beats, unnecessary backup pulses and threshold searches, and therefore, provides added benefits in energy saving obtained by Autocapture.
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- Eskilsson, K, et al.
(författare)
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DNA-surfactant complexes at solid surfaces
- 2001
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Ingår i: Langmuir. - 0743-7463 .- 1520-5827. ; 17, s. 1666-1669
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we report on the adsorption of complexes between DNA of different molecular weight and a cationic surfactant, cetyltrimethylammonium bromide (CTAB), on hydrophobized and hydrophilic negatively charged silica surfaces as measured by ellipsometry. We will demonstrate how the adsorption is affected by the state of the DNA-surfactant complexes formed in bulk solution. High molecular weight DNA molecules, which condense (transform from coil to globule state) on addition of small amounts of cationic surfactants, do not adsorb on hydrophilic silica prior to phase separation. However, DNA-surfactant complexes formed from low molecular weight DNA were found to adsorb. For these complexes surfactants interact with DNA, without condensation of the DNA. Adsorbed DNA-surfactant complexes can easily be removed from the hydrophilic silica surface when replacing the bulk DNA-surfactant solution with pure salt solution. At the hydrophobic surface the DNA adsorbs without addition of cationic surfactant. However, with addition of a very low amount of surfactant, a rapid increase in adsorbed amount and a simultaneous decrease in adsorbed layer thickness are observed. This compaction of the adsorbed layer is to some extent reversible when replacing the bulk DNA-surfactant solution with pure salt solution.
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- Lindman, Björn, et al.
(författare)
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DNA-lipid systems. An amphiphile self-assembly and polymer-surfactant perspective
- 2002
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Ingår i: Lipid and Polymer-Lipid Systems. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0340-255X .- 1437-8027. - 9783540430018 ; 120, s. 52-63
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Konferensbidrag (refereegranskat)abstract
- The interaction between DNA and oppositely charged surfactants has been investigated by several techniques, like fluorescence microscopy, electron microscopy, phase diagram determination, and ellipsometry. The phase behaviour is more strongly associative than that in previously studied systems. A precipitate is formed for very low amounts of surfactant and DNA. DNA compaction is a general phenomenon in the presence of multivalent ions and positively charged surfaces; because of the high charge density there are strong attractive ion correlation effects. The interaction between DNA and catanionic mixtures (i.e., mixtures of cationic and anionic surfactants) was also investigated. We observed that DNA compacts and adsorbs onto the surface of positively charged vesicles and that the addition of anionic surfactant can release free DNA back into solution from a compact globular complex between DNA and cationic surfactant. Finally, we investigated DNA interactions with polycations, chitosans with different chain lengths, by fluorescence microscopy, in vivo transfections assays and cryogenic transmission electron microscopy. The general conclusion is that a chitosan effective in promoting compaction is also efficient in transfection.
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