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Träfflista för sökning "LAR1:gu ;srt2:(2010);pers:(Ewing Andrew G 1957)"

Sökning: LAR1:gu > (2010) > Ewing Andrew G 1957

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1.
  • Adams, Kelly L., et al. (författare)
  • Steady-State Electrochemical Determination of Lipidic Nanotube Diameter Utilizing an Artificial Cell Model
  • 2010
  • Ingår i: Analytical Chemistry. - 1520-6882. ; 82:3, s. 1020-1026
  • Tidskriftsartikel (refereegranskat)abstract
    • By exploiting the capabilities of steady-state electrochemical measurements, we have measured the inner diameter of a lipid nanotube using Fick’s first law of diffusion in conjunction with an imposed linear concentration gradient of electroactive molecules over the length of the nanotube. Fick’s law has been used in this way to provide a direct relationship between the nanotube diameter and the measurable experimental parameters Δi (change in current) and nanotube length. Catechol was used to determine the Δi attributed to its flux out of the nanotube. Comparing the nanotube diameter as a function of nanotube length revealed that membrane elastic energy was playing an important role in determining the size of the nanotube and was different when the tube was connected to either end of two vesicles or to a vesicle on one end and a pipet tip on the other. We assume that repulsive interaction between neck regions can be used to explain the trends observed. This theoretical approach based on elastic energy considerations provides a qualitative description consistent with experimental data.
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2.
  • Cans, Ann-Sofie, 1971-, et al. (författare)
  • Tools to monitor exocytosis: a focus on new fluorescent probes and methods
  • 2010
  • Ingår i: Cellscience Reviews. - 1742-8130. ; 6:3, s. 104-22
  • Tidskriftsartikel (refereegranskat)abstract
    • A great deal of research has been focused on unraveling the processes governing the exocytotic pathway and the extent of release during the process. Arguments abound for and against both the occurrence and significance of full release during exocytosis and partial release including kiss-and-run events. Several optical methods to directly observe the exocytosis process have been developed and here we focus on fluorescence methods and probes for this work. Although, fluorescence imaging has been used for cell experiments for decades, in the last two decades a plethora of new approaches has arrived on the scene. These include application of new microscopy techniques, like total internal reflectance and stimulated emission depletion that are offering new ways to circumvent the limits of far field microscopy with diffraction limit of 200 nm, and allow tracking of single synaptic vesicles. For selective imaging of synaptic vesicles the introduction of methods to stain the vesicular compartment have involved developing probes of the vesicular membrane and intravesicular solution, nanoparticle quantum dots that can be observed during exocytosis but not via the fusion pore, and fluorescent false neurotransmitters.
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3.
  • Dong, Yan, et al. (författare)
  • Probing Exocytosis at Single Cells using Electrochemistry
  • 2010
  • Ingår i: Chemical Cytometry: Ultrasensive Analysis of Single Cells (ed C. Lu). - Weinheim : Wiley-VCH Verlag GmbH & Co.. - 978-3-527-32495-8 ; s. 159-174
  • Bokkapitel (övrigt vetenskapligt)
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4.
  • Kuklinski, Nicholas J., et al. (författare)
  • Biogenic Amines in Microdissected Brain Regions of Drosophila melanogaster Measured with Mice liar Electrokinetic Capillary Chromatography-Electrochemical Detection
  • 2010
  • Ingår i: ANALYTICAL CHEMISTRY. - 0003-2700. ; 82:18, s. 7729-7735
  • Tidskriftsartikel (refereegranskat)abstract
    • Micellar electrokinetic chromatography with electrochemical detection has been used to quantify biogenic amines in microdissected Drosophila melanogaster brains and brain regions. The effects of pigment from the relatively large fly eyes on the separation have been examined to find that the red pigment from the compound eye masks much of the signal from biogenic amines. The brains of white mutant flies, which have characteristically low pigment in the eyes, have a significantly simplified separation profile in comparison to the red-eyed, wild-type, Canton S fly. Yet, the white mutant flies were found to have significantly less amounts of dopamine, I-3,4-dihydroxyphenylalanine (L-DOPA), salsolinol, and N-acetyltyramine in their dissected brains when compared to dissected brains of Canton S flies. In addition, significant variation has been observed in the dissected brains between individual flies that might be related to changes in neurotransmitter turnover. The transgenic GFP fly line (TH-GFP), for which the overall profile of biogenic amines is not found to be significantly different from Canton S, can be used to visualize the location of dopamine neurons. Biogenic amines were then quantified in three brain regions observed to have dopamine levels, the central brain, optic lobes, and posterior superiormedial proto-cerebrum (PPM1) region.
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5.
  • Kuklinski, Nicholas J., et al. (författare)
  • Determination of salsolinol, norsalsolinol, and twenty-one biogenic amines using micellar electrokinetic capillary chromatography-electrochemical detection
  • 2010
  • Ingår i: ELECTROPHORESIS. - 0173-0835. ; 31:11, s. 1886-1893
  • Tidskriftsartikel (refereegranskat)abstract
    • Micellar electrokinetic chromatography coupled to amperometric electrochemical detection was used to resolve and then quantify biogenic amines and metabolites within the fruit fly Drosophila melanogaster. A new separation scheme was devised to allow resolution of 24 compounds of interest. This was accomplished by precisely controlling the amount of base added to the background buffer, optimizing the resolution of the separation, and then calculating the pH. Here we focused on measurements of six of the analytes that are thought to be involved in the response to alcohol, dopamine, salsolinol, norsalsolinol, N-acetyloctopamine, octopamine, and N-acetyldopamine. These were identified and quantified within the fly head. We believe that the identification of salsolinol and norsalsolinol in the fly brain is novel.
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6.
  • Kuklinski, Nicholas J., et al. (författare)
  • Micellar capillary electrophoresis - Electrochemical detection of neurochemicals from Drosophila
  • 2010
  • Ingår i: JOURNAL OF SEPARATION SCIENCE. - 1615-9306. ; 33:3, s. 388-393
  • Tidskriftsartikel (refereegranskat)abstract
    • The fruit fly is one of the most heavily studied model organisms for genetics research and has significantly contributed to the molecular, cellular, and evolutionary understandings of human behavior Recent research in the analytical chemistry of the fruit fly has focused on developing methods to obtain highly sensitive chemical quantification information of Drosophila melanogaster, especially looking at the nervous system We provide a brief overview of work in the area of CE of the fly head and brain
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7.
  • Kurczy, Michael E., 1980-, et al. (författare)
  • Mass spectrometry imaging of mating Tetrahymena show that changes in cell morphology regulate lipid domain formation
  • 2010
  • Ingår i: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA. - 0027-8424. ; 107:7, s. 2751-2756
  • Tidskriftsartikel (refereegranskat)abstract
    • Mass spectrometry imaging has been used here to suggest that changes in membrane structure drive lipid domain formation in mating single-cell organisms. Chemical studies of lipid bilayers in both living and model systems have revealed that chemical composition is coupled to localized membrane structure. However, it is not clear if the lipids that compose the membrane actively modify membrane structure or if structural changes cause heterogeneity in the surface chemistry of the lipid bilayer. We report that time-of-flight secondary ion mass spectrometry images of mating Tetrahymena thermophila acquired at various stages during mating demonstrate that lipid domain formation, identified as a decrease in the lamellar lipid phosphatidylcholine, follows rather than precedes structural changes in the membrane. Domains are formed in response to structural changes that occur during cell-to-cell conjugation. This observation has wide implications in all membrane processes.
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8.
  • Kurczy, Michael E., 1980-, et al. (författare)
  • Nanotome Cluster Bombardment to Recover Spatial Chemistry After Preparation of Biological Samples for SIMS Imaging
  • 2010
  • Ingår i: JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY. - 1044-0305. ; 21:5, s. 833-836
  • Tidskriftsartikel (refereegranskat)abstract
    • A C-60(+) cluster ion projectile is employed for sputter cleaning biological surfaces to reveal spatio-chemical information obscured by contamination overlayers. This protocol is used as a supplemental sample preparation method for time of flight secondary ion mass spectrometry (ToF-SIMS) imaging of frozen and freeze-dried biological materials. Following the removal of nanometers of material from the surface using sputter cleaning, a frozen-patterned cholesterol film and a freeze-dried tissue sample were analyzed using ToF-SIMS imaging. In both experiments, the chemical information was maintained after the sputter dose, due to the minimal chemical damage caused by C-60(+) bombardment. The damage to the surface produced by freeze-drying the tissue sample was found to have a greater effect on the loss of cholesterol signal than the sputter-induced damage. In addition to maintaining the chemical information, sputtering is not found to alter the spatial distribution of molecules on the surface. This approach removes artifacts that might obscure the surface chemistry of the sample and are common to many biological sample preparation schemes for ToF-SIMS imaging.
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9.
  • Lanekoff, Ingela, 1975-, et al. (författare)
  • Time of Flight Mass Spectrometry Imaging of Samples Fractured In Situ with a Spring-Loaded Trap System.
  • 2010
  • Ingår i: Analytical chemistry. - 1520-6882. ; 82:15, s. 6652-6659
  • Tidskriftsartikel (refereegranskat)abstract
    • An in situ freeze fracture device featuring a spring-loaded trap system has been designed and characterized for time of flight secondary ion mass spectrometry (TOF SIMS) analysis of single cells. The device employs the sandwich assembly, which is typically used in freeze fracture TOF SIMS experiments to prepare frozen, hydrated cells for high-resolution SIMS imaging. The addition of the spring-loaded trap system to the sandwich assembly offers two advances to this sample preparation method. First, mechanizing the fracture by adding a spring standardizes each fracture by removing the need to manually remove the top of the sandwich assembly with a cryogenically cooled knife. A second advance is brought about because the top of the sandwich is not discarded after the sandwich assembly has been fractured. This results in two imaging surfaces effectively doubling the sample size and providing the unique ability to image both sections of a cell bifurcated by the fracture. Here, we report TOF SIMS analysis of freeze fractured rat pheochromocytoma (PC12) cells using a Bi cluster ion source. This work exhibits the ability to obtain single cell chemical images with subcellular lateral resolution from cells preserved in an ice matrix. In addition to preserving the cells, the signal from lipid fragment ions rarely identified in single cells are better observed in the freeze-fractured samples for these experiments. Furthermore, using the accepted argument that K(+) signal indicates a cell that has been fractured though the cytoplasm, we have also identified different fracture planes of cells over the surface. Coupling a mechanized freeze fracture device to high-resolution cluster SIMS imaging will provide the sensitivity and resolution as well as the number of trials required to carry out biologically relevant SIMS experiments.
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10.
  • Makos, MA, et al. (författare)
  • Development and Characterization of a Voltammetric Carbon-Fiber Microelectrode pH Sensor
  • 2010
  • Ingår i: LANGMUIR. - 0743-7463. ; 26:12, s. 10386-10391
  • Tidskriftsartikel (refereegranskat)abstract
    • This work describes the development and characterization of a modified carbon-fiber microelectrode sensor capable of measuring real-time physiological pH changes in biological microenvironments. The reagentless sensor was fabricated under ambient conditions from voltammetric reduction of the diazonium salt Fast Blue RR onto a carbon-fiber surface in aprotic media. Fast-scan cyclic voltammetry was used to probe redox activity of the p-quinone moiety of the surface-bound molecule as a function of pH. In vitro calibration of the sensor in solutions ranging from pH 6.5 to 8.0 resulted in a pH-dependent anodic peak potential response. Flow-injection analysis was used to characterize the modified microelectrode, revealing sensitivity to acidic and basic changes discernible to 0.005 pH units. Furthermore, the modified electrode was used to measure dynamic in vivo pH changes evoked during neurotransmitter release in the central nervous system of the microanalytical model organism Drosophila melanogaster.
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