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Found the following, using "squid cell membrane" as keywords:
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Selective open-channel block of KV1 potassium channels by S-nitrosodithiothreitol (SNDTT)
by Brock, Mathew William, Ph.D., Stanford University, 2003, 214 pages; AAT 3085165
Advisor: Gilly, William F.
School: Stanford University
School Location: United States -- California
Index terms(keywords): Open-channel block, Potassium channels, Nitrosodithiothreitol-S, Voltage-gated potassium channels
Source: DAI-B 64/03, p. 1109, Sep 2003
Source type: DISSERTATION
Subjects: Neurology, Biophysics, Organic chemistry
Publication Number: AAT 3085165
Document URL:
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ProQuest document ID: 765393901
Abstract (Document Summary)
Blockade of voltage-gated K + (Kv) channels is a feature of many large quaternary and tertiary amines. These compounds bind with a 1:1 stoichiometry in an aqueous cavity along the channel pore that is exposed to the cytoplasm only when channels are open. This thesis addresses the action of S-nitrosodithiothreitol (SNDTT; ONSCH 2 CH(OH)CH(OH)CH 2 SNO), which produces qualitatively similar "open-channel block" in Kv channels despite its unconventional (small, electrically neutral, and polar) structure. In whole-cell voltage-clamped squid giant fiber lobe neurons, bath-applied SNDTT causes reversible time-dependent block of delayed-rectifier K + channels, but not Na + or Ca 2+ channels. The inactivation-removed Shaker B (ShBΔ) Kv1 channel expressed in HEK 293 cells is blocked in a similar manner and was used to further characterize the action of SNDTT. Dose-response data for ShBΔ indicate that two molecules of SNDTT can bind to each open channel, but binding of a single molecule is sufficient for block. The dissociation constant for the second molecule bound (0.14 mM) is lower than for the first (0.67 mM), indicating cooperativity. Surprisingly, the steady-state level of block by this electrically neutral compound has a voltage-dependence (∼-0.25 e 0 ) similar in magnitude but opposite in directionality to that reported for amines. Both nitrosyl (-NO) groups on SNDTT (one on each sulfur atom) are required for block, but transfer of these reactive groups to channel cysteine residues is not involved. Competition with internal tetraethylammonium indicates that bath-applied SNDTT crosses the cell membrane to act at an internal site. Through targeted mutagenesis, we have identified two contiguous residues (Thr469 and Ile470) in the channel cavity that are strong determinants of SNDTT sensitivity. At position 469, a side chain -OH group is required for high affinity block, and may form a hydrogen bond with an -NO group on SNDTT. Finally, SNDTT is remarkably selective for Kv1 subfamily channels. When individually expressed in HEK 293 cells, rat Kv1.1-1.6 display profound time-dependent block by SNDTT, an effect not seen for rat Kv2.1, 3.1, or 4.2. SNDTT may therefore be useful as a pharmacological probe of Kv subtype, and may represent the prototype for a new class of pharmaceuticals selectively targeting Kv1 channels.
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Nanoparticles: Engineering, assembly, and biomedical applications
by Kim, Do-Kyung, Ph.D., Kungliga Tekniska Hogskolan (Sweden), 2002, 216 pages; AAT C809956
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School: Kungliga Tekniska Hogskolan (Sweden)
School Location: Sweden
Index terms(keywords): Nanoparticles, Biomedical, Ferrofluids, Superparamagnetism
Source: DAI-C 63/04, p. 854, Winter 2002
Source type: DISSERTATION
Subjects: Materials science
Publication Number: AAT C809956
ISBN: 9172832657
Document URL:
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ProQuest document ID: 725953091
Abstract (Document Summary)
This thesis deals with novel aspects of Nanotechnology through " bottom-up " and " top-down " strategies, applied to biotechnology as an interdisciplinary study.
The main objectives of this thesis are to design SPION (superparamagnetic iron oxide nanoparticles) surface modified with other biocompatible agents, varying from organic to polymer and biocompatible materials, such as proteins. The particles have been introduced to intact organs of living animals (rat brain) to examine how they interact in the brain tissue and to confirm the feasibility of using SPION for biomedical applications such as MR imaging.
Several different types of materials including SPION (first generation), immobilized biocompatible materials on SPION (second generation), for in-vivo biomedical applications, nanowires, nanotubes have been prepared by using different aspects of Nanotechnology. Various processes and techniques for the preparation of functional nanomaterials such as coprecipitaion, microemulsion (μE), and template-assisted electrodeposition are developed.
Core-shell structure nanocomposites are fabricated by template-directed self-assembly ( bottom-up ). Controlled electroless deposition of Au is followed by a subsequent removal of the template core without destroying the formed Au shells. The work also includes the development of microcontact printing (μCP) techniques, where the ink used on the surface of the stamp is made of aminopropyl trimethoxy silane (APTMS). The approach is demonstrated with the formation of 2D and 3D structures.
Several different types of magnetic measurements of SPION are investigated. Authentication of superparamagnetism has been carried out by SQUID measurements, up to 7 Tesla, and evaluating the basic physical properties by the Langevien theory. Electron spin resonance (ESR) measurements have been performed as a function of temperature with different particle sizes. The line width of the ESR spectra can be correlated to the distribution of the SPION exchange interactions. Microwave energy absorption rates of SPION have been calculated using a non-linear fitting to experimental data.
The in-vivo experiments showed that, after injection of starch coated SPION into rat brain parenchyma in striatum, a strong phagocytic uptake of the particles is observed due to their strong affinity to the body cell. Diffusion barriers between blood and neural tissue, in the endothelium of the parenchymal vessels (BBB), in the epithelia of the chroid plexuses, and arachnoid membrane (blood-CSF barriers), severely restrict penetration of several diagnostic agents.
The prediction of SPION transport has been made by the modeling of the movement of a single SPION in a biological capillary system. The model considered the four most important factors, i.e. particle size, capillary diameter, distance between the magnets, and capillary length.
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