| 1. |
- King, Carina, et al.
(författare)
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COVID-19—a very visible pandemic
- 2020
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Ingår i: The Lancet. - : Elsevier. - 0140-6736 .- 1474-547X. ; 396:10248, s. 15-15
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Adams, Kelly L., et al.
(författare)
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In Vitro Electrochemistry of Biological Systems
- 2008
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Ingår i: Annual Reviews of Analytical Chemistry. - : Annual Reviews. - 1936-1327 .- 1936-1335. ; 1, s. 329-355
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Tidskriftsartikel (refereegranskat)abstract
- This article reviews recent work involving electrochemical methods for in vitro analysis of biomolecules, with an emphasis on detection and manipulation at and of single cells and cultures of cells. The techniques discussed include constant potential amperometry, chronoamperometry, cellular electroporation, scanning electrochemical microscopy, and microfluidic platforms integrated with electrochemical detection. The principles of these methods are briefly described, followed in most cases with a short description of an analytical or biological application and its significance. The use of electrochemical methods to examine specific mechanistic issues in exocytosis is highlighted, as a great deal of recent work has been devoted to this application.
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| 3. |
- Adams, Kelly L., et al.
(författare)
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Steady-State Electrochemical Determination of Lipidic Nanotube Diameter Utilizing an Artificial Cell Model
- 2010
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 82:3, s. 1020-1026
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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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| 4. |
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| 5. |
- Arcibal, Imee G, et al.
(författare)
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Recent advances in capillary electrophoretic analysis of individual cells
- 2007
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Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 387:1, s. 51-57
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Tidskriftsartikel (refereegranskat)abstract
- Because variability exists within populations of cells, single-cell analysis has become increasingly important for probing complex cellular environments. Capillary electrophoresis (CE) is an excellent technique for identifying and quantifying the contents of single cells owing to its small volume requirements and fast, efficient separations with highly sensitive detection. Recent progress in both whole-cell and subcellular sampling has allowed researchers to study cellular function in the areas of neuroscience, oncology, enzymology, immunology, and gene expression.
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| 6. |
- Aref, Mohaddeseh A., et al.
(författare)
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Intracellular injection of phospholipids directly alters exocytosis and the fraction of chemical release in chromaffin cells as measured by nano-electrochemistry
- 2020
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Ingår i: Chemical Science. - : Royal Society of Chemistry (RSC). - 2041-6520 .- 2041-6539. ; 11:43, s. 11869-11876
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Tidskriftsartikel (refereegranskat)abstract
- Using a nano-injection method, we introduced phospholipids having different intrinsic geometries into single secretory cells and used single cell amperometry (SCA) and intracellular vesicle impact electrochemical cytometry (IVIEC) with nanotip electrodes to monitor the effects of intracellular incubation on the exocytosis process and vesicular storage. Combining tools, this work provides new information to understand the impact of intracellular membrane lipid engineering on exocytotic release, vesicular content and fraction of chemical release. We also assessed the effect of membrane lipid alteration on catecholamine storage of isolated vesicles by implementing another amperometric technique, vesicle impact electrochemical cytometry (VIEC), outside the cell. Exocytosis analysis reveals that the intracellular nano-injection of phosphatidylcholine and lysophosphatidylcholine decreases the number of released catecholamines, whereas phosphatidylethanolamine shows the opposite effect. These observations support the emerging hypothesis that lipid curvature results in membrane remodeling through secretory pathways, and also provide new evidence for a critical role of the lipid localization in modulating the release process. Interestingly, the IVIEC data imply that total vesicular content is also affected by in situ supplementation of the cells with some lipids, while, the corresponding VIEC results show that the neurotransmitter content in isolated vesicles is not affected by altering the vesicle membrane lipids. This suggests that the intervention of phospholipids inside the cell has its effect on the cellular machinery for vesicle release rather than vesicle structure, and leads to the somewhat surprising conclusion that modulating release has a direct effect on vesicle structure, which is likely due to the vesicles opening and closing again during exocytosis. These findings could lead to a novel regulatory mechanism for the exocytotic or synaptic strength based on lipid heterogeneity across the cell membrane.
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| 7. |
- Aref, Mohaddeseh, et al.
(författare)
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Potentiometric pH Nanosensor for Intracellular Measurements: Real-Time and Continuous Assessment of Local Gradients
- 2021
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 93:47, s. 15744-15751
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Tidskriftsartikel (refereegranskat)abstract
- We present a pH nanosensor conceived for single intracellular measurements. The sensing architecture consisted of a two-electrode system evaluated in the potentiometric mode. We used solid-contact carbon nanopipette electrodes tailored to produce both the indicator (pH nanosensor) and reference electrodes. The indicator electrode was a membrane-based ion-selective electrode containing a receptor for hydrogen ions that provided a favorable selectivity for intracellular measurements. The analytical features of the pH nanosensor revealed a Nernstian response (slope of -59.5 mV/pH unit) with appropriate repeatability and reproducibility (variation coefficients of <2% for the calibration parameters), a fast response time (<5 s), adequate medium-term drift (0.7 mV h(-)(1)), and a linear range of response including physiological and abnormal cell pH levels (6.0-8.5). In addition, the position and configuration of the reference electrode were investigated in cell-based experiments to provide unbiased pH measurements, in which both the indicator and reference electrodes were located inside the same cell, each of them inside two neighboring cells, or the indicator electrode inside the cell and the reference electrode outside of (but nearby) the studied cell. Finally, the pH nanosensor was applied to two cases: (i) the tracing of the pH gradient from extra-to intracellular media over insertion into a single PC12 cell and (ii) the monitoring of variations in intracellular pH in response to exogenous administration of pharmaceuticals. It is anticipated that the developed pH nanosensor, which is a label-free analytical tool, has high potential to aid in the investigation of pathological states that manifest in cell pH misregulation, with no restriction in the type of targeted cells.
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| 8. |
- Asadpour, Farzaneh, et al.
(författare)
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Vesicular release dynamics are altered by the interaction between the chemical cargo and vesicle membrane lipids
- 2021
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Ingår i: Chemical Science. - : Royal Society of Chemistry (RSC). - 2041-6520 .- 2041-6539. ; 12:30, s. 10273-10278
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Tidskriftsartikel (refereegranskat)abstract
- The release of the cargo from soft vesicles, an essential process for chemical delivery, is mediated by multiple factors. Among them, the regulation by the interaction between the chemical cargo species and the vesicular membrane, widely existing in all vesicles, has not been investigated to date. Yet, these interactions hold the potential to complicate the release process. We used liposomes loaded with different monoamines, dopamine (DA) and serotonin (5-HT), to simulate vesicular release and to monitor the dynamics of chemical release from isolated vesicles during vesicle impact electrochemical cytometry (VIEC). The release of DA from liposomes presents a longer release time compared to 5-HT. Modelling the release time showed that DA filled vesicles had a higher percentage of events where the time for the peak fall was better fit to a double exponential (DblExp) decay function, suggesting multiple kinetic steps in the release. By fitting to a desorption-release model, where the transmitters adsorbed to the vesicle membrane, the dissociation rates of DA and 5-HT from the liposome membrane were estimated. DA has a lower desorption rate constant, which leads to slower DA release than that observed for 5-HT, whereas there is little difference in pore size. The alteration of vesicular release dynamics due to the interaction between the chemical cargo and vesicle membrane lipids provides an important mechanism to regulate vesicular release in chemical and physiological processes. It is highly possible that this introduces a fundamental chemical regulation difference between transmitters during exocytosis.
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| 9. |
- Barut, Inci, 1984, et al.
(författare)
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Correlative Cellular Mass Spectrometry Imaging and Amperometry Show Dose Dependent Changes in Lipid Composition and Exocytosis
- 2023
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Ingår i: Angewandte Chemie - International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 62:15
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Tidskriftsartikel (refereegranskat)abstract
- Aberrant functioning of the proteasome has been associated with crucial pathologic conditions including neurodegeneration. Yet, the complex underlying causes at the cellular level remain unclear and there are conflicting reports of neuroprotective to neurodegenerative effects of proteasomal inhibitors such as lactacystin that are utilised as models for neurodegenerative diseases. The conflicting results may be associated with different dose regimes of lactacystin and hence we have performed a dose dependent study of the effects of lactacystin to identify concurrent changes in the cell membrane lipid profile and the dynamics of exocytosis using a combination of surface sensitive mass spectrometry and single cell amperometry. Significant changes of negatively charged lipids were associated with different lactacystin doses that showed a weak correlation with exocytosis while changes in PE and PE−O lipids showed dose dependent changes correlated with initial pore formation and total release of vesicle content respectively.
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| 10. |
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| 11. |
- Becquart, Cécile, et al.
(författare)
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Intracellular Absolute Quantification of Oligonucleotide Therapeutics by NanoSIMS
- 2022
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 94:29, s. 10549-10556
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Tidskriftsartikel (refereegranskat)abstract
- Antisense oligonucleotide (ASO)-based therapeutics hold great potential for the treatment of a variety of diseases. Therefore, a better understanding of cellular delivery, uptake, and trafficking mechanisms of ASOs is highly important for early-stage drug discovery. In particular, understanding the biodistribution and quantifying the abundance of ASOs at the subcellular level are needed to fully characterize their activity. Here, we used a combination of electron microscopy and NanoSIMS to assess the subcellular concentrations of a 34S-labeled GalNAc-ASO and a naked ASO in the organelles of primary human hepatocytes. We first cross-validated the method by including a 127I-labeled ASO, finding that the absolute concentration of the lysosomal ASO using two independent labeling strategies gave matching results, demonstrating the strength of our approach. This work also describes the preparation of external standards for absolute quantification by NanoSIMS. For both the 34S and 127I approaches used for our quantification methodology, we established the limit of detection (5 and 2 μM, respectively) and the lower limit of quantification (14 and 5 μM, respectively).
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| 12. |
- Berglund, E. C., et al.
(författare)
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Freeze-Drying as Sample Preparation for Micellar Electrokinetic Capillary Chromatography-Electrochemical Separations of Neurochemicals in Drosophila Brains
- 2013
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 85:5, s. 2841-2846
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Tidskriftsartikel (refereegranskat)abstract
- Micellar electrokinetic capillary chromatography with electrochemical detection has been used to quantify biogenic amines in freeze-dried brains of Drosophila melanogaster. Freeze-drying samples offers a way to preserve the biological sample while making dissection of these tiny samples easier and faster. Fly samples were extracted in cold acetone and dried in a rotary evaporator. Extraction and drying times were optimized in order to avoid contamination by red pigment from the fly eyes and still have intact brain structures. Single freeze-dried fly brain samples were found to produce representative electropherograms as a single hand-dissected brain sample. With utilization of the faster dissection time that freeze-drying affords, the number of brains in a fixed homogenate volume can be increased to concentrate the sample. Thus, concentrated brain samples containing five or fifteen preserved brains were analyzed for their neurotransmitter content, and four analytes; N-acetyloctopamine, N-acetylserotonin, N-acetyltyramine, and N-acetyldopamine were found to correspond well with previously reported values.
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| 13. |
- Berglund, E Carina, et al.
(författare)
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Oral administration of methylphenidate blocks the effect of cocaine on uptake at the Drosophila dopamine transporter.
- 2013
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Ingår i: ACS chemical neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 4:4, s. 566-74
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Tidskriftsartikel (refereegranskat)abstract
- Although our understanding of the actions of cocaine in the brain has improved, an effective drug treatment for cocaine addiction has yet to be found. Methylphenidate binds the dopamine transporter and increases extracellular dopamine levels in mammalian central nervous systems similar to cocaine, but it is thought to elicit fewer addictive and reinforcing effects owing to slower pharmacokinetics for different routes of administration between the drugs. This study utilizes the fruit fly model system to quantify the effects of oral methylphenidate on dopamine uptake during direct cocaine exposure to the fly CNS. The effect of methylphenidate on the dopamine transporter has been explored by measuring the uptake of exogenously applied dopamine. The data suggest that oral consumption of methylphenidate inhibits the Drosophila dopamine transporter and the inhibition is concentration dependent. The peak height increased to 150% of control when cocaine was used to block the dopamine transporter for untreated flies but only to 110% for methylphenidate-treated flies. Thus, the dopamine transporter is mostly inhibited for the methylphenidate-fed flies before the addition of cocaine. The same is true for the rate of the clearance of dopamine measured by amperometry. For untreated flies the rate of clearance changes 40% when the dopamine transporter is inhibited with cocaine, and for treated flies the rate changes only 10%. The results were correlated to the in vivo concentration of methylphenidate determined by CE-MS. Our data suggest that oral consumption of methylphenidate inhibits the Drosophila dopamine transporter for cocaine uptake, and the inhibition is concentration dependent.
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| 14. |
- Borges, R., et al.
(författare)
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The dynamic nature of exocytosis from large secretory vesicles. A view from electrochemistry and imaging
- 2023
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Ingår i: Cell Calcium. - : Elsevier BV. - 0143-4160. ; 110
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Tidskriftsartikel (refereegranskat)abstract
- In this brief review, we discuss the factors that modulate the quantum size and the kinetics of exocytosis. We also discuss the determinants which motivate the type of exocytosis from the so-called kiss-and-run to full fusion and along the intermediate mode of partial release. Kiss-and-run release comprises the transient opening of a nanometer (approx. 2 nm diameter) fusion pore between vesicle and plasma membrane allowing a small amount of release. Partial release comprises a larger more extended opening of the pore to allow a larger fraction of released vesicle content and is what is observed as normal full release in most electrochemical measurements. Partial release appears to be dominant in dense core vesicles and perhaps synaptic vesicles. The concept of partial release leads to the fraction released as a plastic component of exocytosis. Partial vesicular distension and the kinetics of exocytosis can be modulated by second messengers, physiological modulators, and drugs. This concept adds a novel point of regulation for the exocytotic process.
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| 15. |
- Brusselaers, N., et al.
(författare)
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Evaluation of science advice during the COVID-19 pandemic in Sweden
- 2022
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Ingår i: Humanities & Social Sciences Communications. - : Springer Science and Business Media LLC. - 2662-9992. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Sweden was well equipped to prevent the pandemic of COVID-19 from becoming serious. Over 280 years of collaboration between political bodies, authorities, and the scientific community had yielded many successes in preventive medicine. Sweden's population is literate and has a high level of trust in authorities and those in power. During 2020, however, Sweden had ten times higher COVID-19 death rates compared with neighbouring Norway. In this report, we try to understand why, using a narrative approach to evaluate the Swedish COVID-19 policy and the role of scientific evidence and integrity. We argue that that scientific methodology was not followed by the major figures in the acting authorities-or the responsible politicians-with alternative narratives being considered as valid, resulting in arbitrary policy decisions. In 2014, the Public Health Agency merged with the Institute for Infectious Disease Control; the first decision by its new head (Johan Carlson) was to dismiss and move the authority's six professors to Karolinska Institute. With this setup, the authority lacked expertise and could disregard scientific facts. The Swedish pandemic strategy seemed targeted towards "natural" herd-immunity and avoiding a societal shutdown. The Public Health Agency labelled advice from national scientists and international authorities as extreme positions, resulting in media and political bodies to accept their own policy instead. The Swedish people were kept in ignorance of basic facts such as the airborne SARS-CoV-2 transmission, that asymptomatic individuals can be contagious and that face masks protect both the carrier and others. Mandatory legislation was seldom used; recommendations relying upon personal responsibility and without any sanctions were the norm. Many elderly people were administered morphine instead of oxygen despite available supplies, effectively ending their lives. If Sweden wants to do better in future pandemics, the scientific method must be re-established, not least within the Public Health Agency. It would likely make a large difference if a separate, independent Institute for Infectious Disease Control is recreated. We recommend Sweden begins a self-critical process about its political culture and the lack of accountability of decision-makers to avoid future failures, as occurred with the COVID-19 pandemic.
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| 16. |
- Cans, Ann-Sofie, 1971, et al.
(författare)
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Highlights of 20 years of electrochemical measurements of exocytosis at cells and artificial cells
- 2011
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Ingår i: Journal of Solid State Electrochemistry. - : Springer Science and Business Media LLC. - 1433-0768 .- 1432-8488. ; 15:7-8, s. 1437-1450
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Tidskriftsartikel (refereegranskat)abstract
- Advances in electrochemical methodology over the past 30 years have allowed chemical measurements to be made with decreasing amounts of analyte and at smaller spatial dimensions. This has allowed the investigation of single cells and single vesicles in cells either during release of chemical transmitter or separately. The cellular event called exocytosis can be measured with amperometry or cyclic voltammetry as discovered by Wightman and first published in 1990. In addition, the measurement of vesicle contents with electrochemistry is a new approach we have termed electrochemical cytometry. This involves isolation of intact vesicles, separation of the vesicles, and then lysing followed by coulometric analysis of the electroactive vesicle content. In this review, we will highlight work done by us and by others to discuss measurements of exocytosis at single cells and measurements at artificial cell models for studying the biophysical properties of vesicle membrane dynamics and lipid nanotubes connecting artificial cells using electrochemical methods.
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| 17. |
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| 18. |
- Cans, Ann-Sofie, 1971, et al.
(författare)
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Tools to monitor exocytosis: a focus on new fluorescent probes and methods
- 2010
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Ingår i: Cellscience Reviews. - 1742-8130. ; 6:3, s. 104-22
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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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| 19. |
- Da Silva Lima, Alex, et al.
(författare)
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Electrochemistry at and in single cells
- 2020
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Ingår i: Electrochemistry for Bioanalysis. Bhavik Patel (red.). - : Elsevier. - 9780128212035 ; , s. 125-160
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter introduces the reader to electrochemical methods for analysis of extracellular events and applications of electrodes for measurements in single cell cytoplasm and organelles. Applications include measurements of exocytosis, the process by which chemical species are released by cells, and excretion of reactive oxygen and nitrogen species as well as cholesterol in cell membranes. In addition, new methods have been devised to measure the electroactive contents of single organelles both removed from cells and in living cells. A large part of the success of these methods has come from the development of new micro and nano electrodes. © 2020 Elsevier Inc. All rights reserved.
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| 20. |
- Ding, J., et al.
(författare)
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Inhibition of HMGCoA Reductase Reveals An Unexpected Role for Cholesterol During PGC Migration in the Mouse.
- 2008
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Ingår i: BMC developmental biology. - 1471-213X. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT: BACKGROUND: Primordial germ cells (PGCs) are the embryonic precursors of the sperm and eggs. Environmental or genetic defects that alter PGC development can impair fertility or cause formation of germ cell tumors. RESULTS: We demonstrate a novel role for cholesterol during germ cell migration in mice. Cholesterol was measured in living tissue dissected from mouse embryos and was found to accumulate within the developing gonads as germ cells migrate to colonize these structures. Cholesterol synthesis was blocked in culture by inhibiting the activity of HMG CoA reductase (HMGCR) resulting in germ cell survival and migration defects. These defects were rescued by co-addition of isoprenoids and cholesterol, but neither compound alone was sufficient. In contrast, loss of the last or penultimate enzyme in cholesterol biosynthesis did not alter PGC numbers or position in vivo. However embryos that lack these enzymes do not exhibit cholesterol defects at the stage at which PGCs are migrating. This demonstrates that during gestation, the cholesterol required for PGC migration can be supplied maternally. CONCLUSIONS: In the mouse, cholesterol is required for PGC survival and motility. It may act cell-autonomously by regulating clustering of growth factor receptors within PGCs or non cell-autonomously by controlling release of growth factors required for PGC guidance and survival.
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| 21. |
- Dong, Yan, et al.
(författare)
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Amperometric measurements of catecholamine release from single vesicles in MN9D cells.
- 2008
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Ingår i: Journal of neurochemistry. - : Wiley. - 1471-4159 .- 0022-3042. ; 107:6, s. 1589-95
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Tidskriftsartikel (refereegranskat)abstract
- MN9D cells have been used as a successful model to investigate dopamine pharmacology and to test the specific effects of drugs for the treatment of Parkinson's disease. However, quantitative measurements of quantal release from these cells have not been carried out. In this work, we used amperometry to investigate catecholamine release from MN9D cells. Amperometric events were observed in both undifferentiated and differentiated (butyric acid-treated) cells. An increase in quantal size and half-width was observed for differentiated cells versus undifferentiated cells; however, the number of events per cell and the amplitude remained constant. In transmission electron microscopy images, no obvious cluster of small synaptic vesicles was observed, and large dense-core vesicles were present in the cell body of undifferentiated cells; however, after differentiation, vesicles were concentrated in the cell processes. In differentiated cells, l-DOPA caused an increase in quantal size and half-width, which could be blocked by the vesicular monoamine transporter inhibitor, reserpine.
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| 22. |
- Dong, Y., et al.
(författare)
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Pituitary Adenylate Cyclase Activating Polypeptide Modulates Catecholamine Storage and Exocytosis in PC12 Cells
- 2014
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- A number of efforts have been made to understand how pituitary adenylate cyclase activating polypeptide (PACAP) functions as a neurotrophic and neuroprotective factor in Parkinson's disease (PD). Recently its effects on neurotransmission and underlying mechanisms have generated interest. In the present study, we investigate the effects of PACAP on catecholamine storage and secretion in PC12 cells with amperometry and transmission electron microscopy (TEM). PACAP increases quantal release induced by high K+ without significantly regulating the frequency of vesicle fusion events. TEM data indicate that the increased volume of the vesicle is mainly the result of enlargement of the fluidic space around the dense core. Moreover, the number of docked vesicles isn't modulated by PACAP. When cells are acutely treated with L-DOPA, the vesicular volume and quantal release both increase dramatically. It is likely that the characteristics of amperometric spikes from L-DOPA treated cells are associated with increased volume of individual vesicles rather than a direct effect on the mechanics of exocytosis. Treatment with PACAP versus L-DOPA results in different profiles of the dynamics of exocytosis. Release via the fusion pore prior to full exocytosis was observed with the same frequency following treatment with PACAP and L-DOPA. However, release events have a shorter duration and higher average current after PACAP treatment compared to L-DOPA. Furthermore, PACAP reduced the proportion of spikes having rapid decay time and shortened the decay time of both fast and slow spikes. In contrast, the distributions of the amperometric spike decay for both fast and slow spikes were shifted to longer time following L-DOPA treatment. Compared to L-DOPA, PACAP may produce multiple favorable effects on dopaminergic neurons, including protecting dopaminergic neurons against neurodegeneration and potentially regulating dopamine storage and release, making it a promising therapeutic agent for the treatment of PD.
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| 23. |
- Dong, Yan, et al.
(författare)
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Probing Exocytosis at Single Cells using Electrochemistry
- 2010
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Ingår i: Chemical Cytometry: Ultrasensive Analysis of Single Cells (ed C. Lu). - Weinheim : Wiley-VCH Verlag GmbH & Co.. - 9783527324958 ; , s. 159-174
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 24. |
- Dowlatshahi Pour, Masoumeh, 1976, et al.
(författare)
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An investigation on the mechanism of sublimed DHB matrix on molecular ion yields in SIMS imaging of brain tissue
- 2016
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Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 408:12, s. 3071-3081
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Tidskriftsartikel (refereegranskat)abstract
- We have characterized the use of sublimation to deposit matrix-assisted laser desorption/ionization (MALDI) matrices in secondary ion mass spectrometry (SIMS) analysis, i.e. matrix-enhanced SIMS (ME-SIMS), a common surface modification method to enhance sensitivity for larger molecules and to increase the production of intact molecular ions. We use sublimation to apply a thin layer of a conventional MALDI matrix, 2,5-dihydroxybenzoic acid (DHB), onto rat brain cerebellum tissue to show how this technique can be used to enhance molecular yields in SIMS while still retaining a lateral resolution around 2 mu m and also to investigate the mechanism of this enhancement. The results here illustrate that cholesterol, which is a dominant lipid species in the brain, is decreased on the tissue surface after deposition of matrix, particularly in white matter. The decrease of cholesterol is followed by an increased ion yield of several other lipid species. Depth profiling of the sublimed rat brain reveals that the lipid species are de facto extracted by the DHB matrix and concentrated in the top most layers of the sublimed matrix. This extraction/concentration of lipids directly leads to an increase of higher mass lipid ion yield. It is also possible that the decrease of cholesterol decreases the potential suppression of ion yield caused by cholesterol migration to the tissue surface. This result provides us with significant insights into the possible mechanisms involved when using sublimation to deposit this matrix in ME-SIMS.
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| 25. |
- Dowlatshahi Pour, Masoumeh, 1976, et al.
(författare)
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Food-induced changes of lipids in rat neuronal tissue visualized by ToF-SIMS imaging
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Time of flight secondary ion mass spectrometry (ToF-SIMS) was used to image the lipid localization in brain tissue sections from rats fed specially processed cereals (SPC). An IonTof 5 instrument equipped with a Bi cluster ion gun was used to analyze the tissue sections. Data from 15 brain samples from control and cereal-fed rats were recorded and exported to principal components analysis (PCA). The data clearly show changes of certain lipids in the brain following cereal feeding. PCA score plots show a good separation in lipid distribution between the control and the SPC-fed group. The loadings plot reveal that the groups separated mainly due to changes in cholesterol, vitamin E and c18:2, c16:0 fatty acid distribution as well as some short chain monocarboxylic fatty acid compositions. These insights relate to the working mechanism of SPC as a dietary supplement. SPC is thought to activate antisecretory factor (AF), an endogenous protein with regulatory function for inflammation and fluid secretion. These data provide insights into lipid content in brain following SPC feeding and suggest a relation to activating AF.
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| 26. |
- Dowlatshahi Pour, Masoumeh, 1976, et al.
(författare)
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Mass spectrometric profiling of lipids in intestinal tissue from rats fed cereals processed for medical conditions
- 2016
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Ingår i: Biointerphases. - : American Vacuum Society. - 1934-8630 .- 1559-4106. ; 11:2, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used for lipid profiling of intestine tissue sections from rats fed specially processed cereals and rats fed ordinary feed as a control. This cereal is known to increase the activity of antisecretory factor in plasma and the exact mechanism for the activation process at the cellular level is unclear. ToF-SIMS has been used to track food induced changes in lipid content in intestinal tissue sections to gain insight into the possible mechanisms involved. Data from 20 intestine sections belonging to four different rats from each group of control and specially processed cereals-fed rats were obtained using the stage scan macroraster with a lateral resolution of 5 lm. Data were subsequently subjected to orthogonal partial least squares discriminant analysis. The data clearly show that changes of certain lipids are induced by the specially processed cereal feed. Scores plots show a well-defined separation between the two groups. The corresponding loading plots reveal that the groups separate mainly due to changes of vitamin E, phosphocholine, and phosphosphingolipid fragments, and that for the c18:2 fatty acid. The observed changes in lipids might give insight into the working mechanisms of antisecretory factor in the body, and this has been successfully used to understand the working mechanism of specially processed cereal-induced antisecretory factor activation in intestine.
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| 27. |
- Dowlatshahi Pour, Masoumeh, 1976, et al.
(författare)
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Mass spectrometry imaging as a novel approach to measure hippocampal zinc
- 2019
-
Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 34:8, s. 1581-1587
-
Tidskriftsartikel (refereegranskat)abstract
- Zinc (Zn2+) is an essential trace element that plays crucial roles in the functioning of hundreds of enzymes and DNA binding transcription factors. Zinc is also an essential neuromodulator and can act as a potent neurotoxin in excitotoxic brain injury after seizures, strokes, and brain trauma where high levels of Zn2+ can cause irreparable brain damage in certain brain regions. However, the mechanism of neurotoxicity has not been fully understood yet and is still under debate. In the present study, we have developed a time of flight secondary ion mass spectrometry (ToF-SIMS) imaging method to investigate the distribution of zinc in the rat brain. The zinc distribution in hippocampus sections from healthy rats and rats exposed to traumatic brain injury was imaged and the results were compared to those from conventional zinc-probe based fluorescence microscopy. Two related zinc species, ZnOH3 + and ZnO2H+, can successfully be visualized by ToF-SIMS in the rat hippocampus. Statistical data analysis of the image data demonstrated a substantial increase of both ZnOH3 + and ZnO2H+ in the zinc related species in the acute brain injury tissue. Our findings positively support the fact that toxic vesicular zinc accumulation might not be the sole source for neuronal degeneration following traumatic brain injuries. Also, we could successfully apply ToF-SIMS imaging for the first time to visualize the zinc content and distribution across hippocampus sections. Consequently, ToF-SIMS is a powerful method to further investigate biological phenomena such as seizures, ischemia, and strokes and also other forms of cellular damage in the central nervous system.
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| 28. |
- Drake, Thomas M., et al.
(författare)
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Outcomes following small bowel obstruction due to malignancy in the national audit of small bowel obstruction
- 2019
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Ingår i: European Journal of Surgical Oncology. - : Elsevier BV. - 0748-7983 .- 1532-2157. ; 45:12, s. 2319-2324
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical Oncology Introduction: Patients with cancer who develop small bowel obstruction are at high risk of malnutrition and morbidity following compromise of gastrointestinal tract continuity. This study aimed to characterise current management and outcomes following malignant small bowel obstruction. Methods: A prospective, multicentre cohort study of patients with small bowel obstruction who presented to UK hospitals between 16th January and 13th March 2017. Patients who presented with small bowel obstruction due to primary tumours of the intestine (excluding left-sided colonic tumours) or disseminated intra-abdominal malignancy were included. Outcomes included 30-day mortality and in-hospital complications. Cox-proportional hazards models were used to generate adjusted effects estimates, which are presented as hazard ratios (HR) alongside the corresponding 95% confidence interval (95% CI). The threshold for statistical significance was set at the level of P ≤ 0.05 a-priori. Results: 205 patients with malignant small bowel obstruction presented to emergency surgery services during the study period. Of these patients, 50 had obstruction due to right sided colon cancer, 143 due to disseminated intraabdominal malignancy, 10 had primary tumours of the small bowel and 2 patients had gastrointestinal stromal tumours. In total 100 out of 205 patients underwent a surgical intervention for obstruction. 30-day in-hospital mortality rate was 11.3% for those with primary tumours and 19.6% for those with disseminated malignancy. Severe risk of malnutrition was an independent predictor for poor mortality in this cohort (adjusted HR 16.18, 95% CI 1.86 to 140.84, p = 0.012). Patients with right-sided colon cancer had high rates of morbidity. Conclusions: Mortality rates were high in patients with disseminated malignancy and in those with right sided colon cancer. Further research should identify optimal management strategy to reduce morbidity for these patient groups.
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| 29. |
- Dunevall, Johan, 1984, et al.
(författare)
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Characterizing the Catecholamine Content of Single Mammalian Vesicles by Collision-Adsorption Events at an Electrode
- 2015
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 137:13, s. 4344-4346
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Tidskriftsartikel (refereegranskat)abstract
- We present the electrochemical response to single adrenal chromaffin vesicles filled with catecholamine hormones as they are adsorbed and rupture on a 33 mu m diameter disk-shaped carbon electrode. The vesicles adsorb onto the electrode surface and sequentially spread out over the electrode surface, trapping their contents against the electrode. These contents are then oxidized, and a current (or amperometric) peak results from each vesicle that bursts. A large number of current transients associated with rupture of single vesicles (86%) are observed under the experimental conditions used, allowing us to quantify the vesicular catecholamine content.
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| 30. |
- Dunevall, Johan, 1984, et al.
(författare)
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Vesicle impact electrochemical cytometry compared to amperometric exocytosis measurements
- 2017
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Ingår i: Current Opinion in Electrochemistry. - : Elsevier BV. - 2451-9103 .- 2451-9111. ; 5:1, s. 85-91
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Tidskriftsartikel (refereegranskat)abstract
- Three new tools are discussed for understanding chemical communication between cells and primarily to delve into the content and structure of nanometer transmitter vesicles. These are amperometric measurements of exocytosis, vesicle impact electrochemical cytometry, and intracellular vesicle impact electrochemical cytometry. These are combining in the end nanoscale mass spectrometry imaging to begin determination of vesicle structure. These methods have provided solid evidence for the concept of open and closed exocytosis leading to partial release of the vesicle content during normal exocytosis. They have also been used to discover cases where the fraction of transmitter released is not changed, and other cases where the vesicle transmitter fraction released is altered, as with zinc, thought to alter cognition. Overall, the combination of these methods is showing us details of vesicular processes that would not be measureable without these micro and nano electrochemical methods.
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| 31. |
- Eves, D J, et al.
(författare)
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Electrochemistry inside and outside single nerve cells
- 2007
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Ingår i: New Frontiers in Ultrasensitive Bioanalysis: Advanced Analytical ChemistryApplications in Nanobiotechnology, Single Molecule Detection, and Single Cell Analysis. - Hoboken : John Wiley & Sons. ; , s. 215-234
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 32. |
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| 33. |
- Ewing, Andrew G, 1957
(författare)
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Electrochemical measurements of transmitters in flies, at cells, and from transmitter vesicles
- 2013
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Ingår i: Abstracts of Papers of the American Chemical Society (Conference: 246th National Meeting of the American-Chemical-Society (ACS)). - 0065-7727.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have developed three electroanalytical methods to measure neurochemicals in ultrasmall biological environments. First, voltammetry in the fly brain has been used to understand the drug action. We have used this to study the action of methylphenidate on that of cocaine with an eventual goal of understanding and remediating cocaine addiction. Second, we have used small electrodes to measure neurotransmitter release from single cells, a method that has become commonplace after twenty years. Here, we have analyzed amperometric peaks corresponding to release at PC12 cells and found stable plateau currents during the decay of the peaks, indicating closing of the vesicle after incomplete release of the vesicular content. From careful analysis of these data, we have proposed a process for most exocytosis events where the vesicle partially opens to release transmitter and then closes directly again, leaving the possibility for both a stable pre and post spike foot to be observed with amperometry. Third, those experiments correlate well with those from the electrochemical cytometry method we developed to count electroactive molecules in individual synaptic vesicles in directly sampled populations from cells or brain tissue. With this method we can compare the total numbers of molecules to those released and only a fraction is in fact released both at cell models and in mammalian brains. Partial release is important in that it produces a new pharmaceutical paradigm and could be important in understanding learning and memory. It also makes it clear that the dynamics of vesicle opening, controlled largely by lipids, might be an important characteristic in neurotransmission.
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| 34. |
- Ewing, Andrew G, 1957, et al.
(författare)
-
Frontiers in Neurochemistry
- 2018
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Ingår i: ChemPhysChem. - : Wiley. - 1439-4235 .- 1439-7641. ; 19, s. 1121-1122
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 35. |
- Ewing, Andrew, 1957
(författare)
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Mass spectrometry imaging of lipids and metabolites: from fruit fly brains to single nanometer vesicles
- 2016
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Ingår i: New Biotechnology. - : Elsevier BV. - 1876-4347 .- 1871-6784. ; 33:Supplement: S Meeting Abstract: O5-1, s. S21-S21
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Tidskriftsartikel (refereegranskat)abstract
- We have been developing mass spectrometry imaging methods to study the process of neurocommunication at the system and cellular level. We focus on PC12 cells as a model of exocytosis and the fly model (Drosophila melanogaster) providing a unique system to examine neurotransmitter release and drug dependence mechanisms in a small, but complete system.Mass spectrometry imaging with ion beams allows spatial resolution of a few micrometers down to 40 nanometers in favorable cases. We have been using secondary ion mass spectrometry (SIMS) with a unique 40-kV argon cluster ion source and the NanoSIMS to measure the lipids across the fly brain and catecholamine in nanometer vesicles, respectively. Here, we have focused on the effect of the drug, methylphenidate, on lipid composition in the brain and find that it varies in a way that might affect learning and memory. We have also used NanoSIMS to measure transmitter in subregions of nanometer vesicles. Combined with other new methods to measure the content of the interior of vesicles, we have begun to investigate the details and implications of open and closed exocytosis on regulation of how the brain works.
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| 36. |
- Gerber, Lorenz, 1976, et al.
(författare)
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Using imaging ToF-SIMS data to determine the cell wall thickness of fibers in wood
- 2014
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Ingår i: Surface and Interface Analysis. - : Wiley. - 1096-9918 .- 0142-2421. ; 46:S1, s. 225-228
-
Tidskriftsartikel (refereegranskat)abstract
- Here, we demonstrate the use of time-of-flight secondary ion mass spectrometry (ToF-SIMS) imaging data for estimation of cell wall thickness in wood samples. Current research in forest biotechnology focuses on transgenic trees with wood properties tailored to specific applications. Appropriate analytical methods to characterize the very heterogeneous wood material are constantly being developed and improved. Chemical imaging of wood by ToF-SIMS represents an interesting tool for this purpose with many applications. In addition to wood chemistry, the impact of specific genetic modifications on wood anatomy needs to be assessed. Cell wall thickness is an important anatomical parameter that among others is used for assessing biomass accumulation. We developed a strategy to estimate cell wall thickness from ToF-SIMS images and implemented it in the open source programming language R'. In brief, random lines are projected over the black and white mask of a ToF-SIMS image, and length values of all line sections that cut across a cell wall are collected. After enough iteration, the shortest values of the obtained count distribution represent the crossing sections normal to the cell walls, hence cell wall thickness. Compared with conventional light microscopy image analysis, TOF-SIMS data offers many advantages such as submicron resolution and additional spectral information for automated annotation of distinct anatomical features. This work underlines the importance of SIMS imaging for studies of wood chemistry and anatomy and provides a new approach to obtain an important wood anatomical parameter from ToF-SIMS data.
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| 37. |
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| 38. |
- Gu, Chaoyi, 1992, et al.
(författare)
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Comparison of Disk and Nanotip Electrodes for Measurement of Single-Cell Amperometry during Exocytotic Release
- 2020
-
Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 92:15, s. 10268-10273
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Tidskriftsartikel (refereegranskat)abstract
- We compare single-cell amperometric measurements of exocytosis from pheochromocytoma (PC12) cells between two types of electrodes, carbon fiber disk microelectrodes and nanotip conical-shape carbon fiber microelectrodes. During the exocytotic process, individual exocytotic release events, measured as current spikes at the electrode, offer quantitative and dynamic information about the chemical release from cells. Using two electrodes gives rise to an unequal distance between the fusion pore and the electrode as well as fusion pore size, which leads to different average spike shapes. Nanotip electrodes show a slightly higher and narrower spike than disk electrodes when measuring exocytosis. The estimated pore-electrode distance and fusion pore size for disk electrodes are 239 and 11.5 nm, while for nanotip electrodes, these are 215 and 18.2 nm, respectively. The data show that nanotip electrodes, despite showing slightly different dynamics for release, are quantitative in measuring the number of molecules released and can be used for quantitative comparison between exocytosis and vesicular content in intracellular vesicle impact electrochemical cytometry.
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| 39. |
- Gu, Chaoyi, 1992, et al.
(författare)
-
Mass spectrometric imaging of plasma membrane lipid alteration correlated with amperometrically measured activity-dependent plasticity in exocytosis
- 2020
-
Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 21:24, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- The mechanism of synaptic plasticity and its link to memory formation are of interest, yet relatively obscure, especially the initial chemical change in the cell membrane following transmitter release. To understand the chemical mechanism of plasticity, we studied how repetitive stimuli regulate certain membrane lipid species to enhance exocytotic release using mass spectrometric imaging. We found that increasing high-curvature lipid species and decreasing low-curvature lipids in the cell membrane favor the formation of a longer-lasting exocytotic fusion pore, resulting in higher release fraction for individual exocytotic events. The lipid changes observed following repetitive stimuli are similar to those after exposure to the cognitive enhancing drug, methylphenidate, examined in a previous study, and offer an interesting point of view regarding the link between plasticity and memory and cognition.
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| 40. |
- Gu, Chaoyi, 1992, et al.
(författare)
-
Omega-3 and-6 Fatty Acids Alter the Membrane Lipid Composition and Vesicle Size to Regulate Exocytosis and Storage of Catecholamines
- 2024
-
Ingår i: ACS CHEMICAL NEUROSCIENCE. - 1948-7193. ; 15:4, s. 816-826
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Tidskriftsartikel (refereegranskat)abstract
- The two essential fatty acids, alpha-linolenic acid and linoleic acid, and the higher unsaturated fatty acids synthesized from them are critical for the development and maintenance of normal brain functions. Deficiencies of these fatty acids have been shown to cause damage to the neuronal development, cognition, and locomotor function. We combined electrochemistry and imaging techniques to examine the effects of the two essential fatty acids on catecholamine release dynamics and the vesicle content as well as on the cell membrane phospholipid composition to understand how they impact exocytosis and by extension neurotransmission at the single-cell level. Incubation of either of the two fatty acids reduces the size of secretory vesicles and enables the incorporation of more double bonds into the cell membrane structure, resulting in higher membrane flexibility. This subsequently affects proteins regulating the dynamics of the exocytotic fusion pore and thereby affects exocytosis. Our data suggest a possible pathway whereby the two essential fatty acids affect the membrane structure to impact exocytosis and provide a potential treatment for diseases and impairments related to catecholamine signaling.
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| 41. |
- Gu, Chaoyi, 1992, et al.
(författare)
-
Plasticity in exocytosis revealed through the effects of repetitive stimuli affect the content of nanometer vesicles and the fraction of transmitter released
- 2019
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 116:43, s. 21409-21415
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical techniques with disk and nano-tip electrodes, together with calcium imaging, were used to examine the effect of short-interval repetitive stimuli on both exocytosis and vesicular content in a model cell line. We show that the number of events decreases markedly with repeated stimuli suggesting a depletion of exocytosis machinery. However, repetitive stimuli induce a more stable fusion pore, leading to an increased amount of neurotransmitter release. In contrast, the total neurotransmitter content inside the vesicles decreases after repetitive stimuli, resulting in a higher average release fraction from each event. We suggest a possible mechanism regarding a link between activity-induced plasticity and fraction of release.
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| 42. |
- Gu, Chaoyi, 1992, et al.
(författare)
-
Simultaneous detection of vesicular content and exocytotic release with two electrodes in and at a single cell
- 2021
-
Ingår i: Chemical Science. - : Royal Society of Chemistry (RSC). - 2041-6520 .- 2041-6539. ; 21, s. 7393-74
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Tidskriftsartikel (refereegranskat)abstract
- We developed a technique employing two electrodes to simultaneously and dynamically monitor vesicular neurotransmitter storage and vesicular transmitter release in and at the same cell. To do this, two electrochemical techniques, single-cell amperometry (SCA) and intracellular vesicle impact electrochemical cytometry (IVIEC), were applied using two nanotip electrodes. With one electrode being placed on top of a cell measuring exocytotic release and the other electrode being inserted into the cytoplasm measuring vesicular transmitter storage, upon chemical stimulation, exocytosis is triggered and the amount of release and storage can be quantified simultaneously and compared. By using this technique, we made direct comparison between exocytotic release and vesicular storage, and investigated the dynamic changes of vesicular transmitter content before, during, and after chemical stimulation of PC12 cells, a neuroendocrine cell line. While confirming that exocytosis is partial, we suggest that chemical stimulation either induces a replenishment of the releasable pool with a subpool of vesicles having higher amount of transmitter storage, or triggers the vesicles within the same subpool to load more transiently at approximately 10-20 s. Thus, a time scale for vesicle reloading is determined. The effect of l-3,4-dihydroxyphenylalanine (l-DOPA), the precursor to dopamine, on the dynamic alteration of vesicular storage upon chemical stimulation for exocytosis was also studied. We found that l-DOPA incubation reduces the observed changes of vesicular storage in regular PC12 cells, which might be due to an increased capacity of vesicular transmitter loading caused by l-DOPA. Our data provide another mechanism for plasticity after stimulation via quantitative and dynamic changes in the exocytotic machinery.
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| 43. |
- Gu, Hui, 1988, et al.
(författare)
-
Amperometry and Electron Microscopy show Stress Granules Induce Homotypic Fusion of Catecholamine Vesicles
- 2024
-
Ingår i: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION. - 1433-7851 .- 1521-3773. ; 63:16
-
Tidskriftsartikel (refereegranskat)abstract
- An overreactive stress granule (SG) pathway and long-lived, stable SGs formation are thought to participate in the progress of neurodegenerative diseases (NDs). To understand if and how SGs contribute to disorders of neurotransmitter release in NDs, we examined the interaction between extracellular isolated SGs and vesicles. Amperometry shows that the vesicular content increases and dynamics of vesicle opening slow down after vesicles are treated with SGs, suggesting larger vesicles are formed. Data from transmission electron microscopy (TEM) clearly shows that a portion of large dense-core vesicles (LDCVs) with double/multiple cores appear, thus confirming that SGs induce homotypic fusion between LDCVs. This might be a protective step to help cells to survive following high oxidative stress. A hypothetical mechanism is proposed whereby enriched mRNA or protein in the shell of SGs is likely to bind intrinsically disordered protein (IDP) regions of vesicle associated membrane protein (VAMP) driving a disrupted membrane between two closely buddled vesicles to fuse with each other to form double-core vesicles. Our results show that SGs induce homotypic fusion of LDCVs, providing better understanding of how SGs intervene in pathological processes and opening a new direction to investigations of SGs involved neurodegenerative disease. Vesicle impact electrochemical cytometry (VIEC) reveals larger molecule number and slower dynamics of vesicles opening after vesicles are treated with stress granules (SGs), implying homotypic fusion between vesicles, confirmed by observation of multi-core vesicles with transmission electron microscopy (TEM). This finding provides new insights into how neural cells regulate exocytosis under oxidative stress and how SGs promote neurodegeneration.
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| 44. |
- Hanrieder, Jörg, 1980, et al.
(författare)
-
High Resolution Metabolite Imaging in the Hippocampus Following Neonatal Exposure to the Environmental Toxin BMAA Using ToF-SIMS
- 2014
-
Ingår i: Acs Chemical Neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 5:7, s. 568-575
-
Tidskriftsartikel (refereegranskat)abstract
- The environmental neurotoxin beta-N-methylamino-L-alanine (BMAA) is suggested to be linked with neurodegenerative disease. In a rat model, neonatal exposure to BMAA induced selective uptake in the hippocampus and caused cell loss, mineralization and astrogliosis as well as learning and memory impairments in adulthood. Moreover, neonatal exposure resulted in increased protein ubiquitination in the cornus ammonis 1 (CA1) region of the adult hippocampus indicating that BMAA may induce protein aggregation. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) based imaging is a powerful technology for spatial profiling of small molecular weight compounds in biological tissues with high chemical specificity and high spatial resolution. The aim of this study was to characterize neurochemical changes in the hippocampus of six month-old rats treated neonatally (postnatal days 9-10) with BMAA. Multivariate data analysis of whole section ToF-SIMS scans was performed to delineate anatomical regions of interest based on their chemical distribution pattern. Further analysis of spectral data obtained from the outlined anatomical regions, including CA1 and dentate gyms (DG) revealed BMAA-induced long-term changes. Increased levels of phospholipids and protein fragments in the histopathologically altered CA1 region as well as phosphate depletion in the DG were observed. Moreover, high resolution SIMS imaging revealed a specific localization of phosphatidylcholine lipids, protein signals and potassium in the histopathologically altered CA1 These findings demonstrate that ToF-SIMS based imaging is a powerful approach for probing biochemical changes in situ and might serve as promising technique for investigating neurotoxin-induced brain pathology.
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| 45. |
- Hanrieder, Jörg, 1980, et al.
(författare)
-
Imaging mass spectrometry in neuroscience.
- 2013
-
Ingår i: ACS chemical neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 4:5, s. 666-79
-
Tidskriftsartikel (refereegranskat)abstract
- Imaging mass spectrometry is an emerging technique of great potential for investigating the chemical architecture in biological matrices. Although the potential for studying neurobiological systems is evident, the relevance of the technique for application in neuroscience is still in its infancy. In the present Review, a principal overview of the different approaches, including matrix assisted laser desorption ionization and secondary ion mass spectrometry, is provided with particular focus on their strengths and limitations for studying different neurochemical species in situ and in vitro. The potential of the various approaches is discussed based on both fundamental and biomedical neuroscience research. This Review aims to serve as a general guide to familiarize the neuroscience community and other biomedical researchers with the technique, highlighting its great potential and suitability for comprehensive and specific chemical imaging.
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| 46. |
- Hanrieder, Jörg, 1980, et al.
(författare)
-
Probing the lipid chemistry of neurotoxin-induced hippocampal lesions using multimodal imaging mass spectrometry
- 2014
-
Ingår i: Surface and Interface Analysis. - : Wiley. - 1096-9918 .- 0142-2421. ; 46:S1, s. 375-378
-
Tidskriftsartikel (refereegranskat)abstract
- The environmental toxin -N-methylamino-l-alanine (BMAA) has been causatively linked to neurodegenerative disease pathology. In a rat model, neonatal BMAA resulted in selective uptake in the hippocampal formation and caused learning and memory impairments in adult animals. Moreover, high dose neonatal BMAA exposure resulted in formation of histopathological lesions in the CA1 region of the adult hippocampus; however, the mechanism underlying BMAA induced neuropathology remains elusive. Imaging mass spectrometry (IMS) is a powerful method for spatial interrogation of biochemical distribution in biological tissue with high chemical specificity. The aim of this study was to therefore characterize the lipid microenvironment of BMAA-induced hippocampal lesions in adult rats using matrix-assisted laser desorption/ionization (MALDI) and time-of-flight SIMS (ToF-SIMS imaging). Multimodal imaging was carried out by ToF-SIMS scans of the hippocampal formation followed by whole tissue scans using MALDI imaging. Multivariate analysis was performed on the SIMS data in order to delineate the spatial biochemistry surrounding the lesions. The data show lesion-specific localization of phosphatidylcholine fragments, suggesting neuroinflammatory glial cell activation. Complementary MALDI imaging data showed increased levels of phosphoethanolamines colocalizing with the proteopathic lesions pointing to macroautophagic mechanisms associated with neurotoxin-induced protein accumulation. Multimodal IMS by means of ToF-SIMS and MALDI mass spectrometry proved to be a powerful technique for neurotoxicological research.
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| 47. |
- Hanrieder, Jörg, 1980, et al.
(författare)
-
Spatial Elucidation of Spinal Cord Lipid- and Metabolite-Regulations in Amyotrophic Lateral Sclerosis
- 2014
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- Amyotrophic lateral sclerosis (ALS) is a devastating, rapidly progressing disease of the central nervous system that is characterized by motor neuron degeneration in the brain stem and the spinal cord. We employed time of flight secondary ion mass spectrometry (ToF-SIMS) to profile spatial lipid-and metabolite-regulations in post mortem human spinal cord tissue from ALS patients to investigate chemical markers of ALS pathogenesis. ToF-SIMS scans and multivariate analysis of image and spectral data were performed on thoracic human spinal cord sections. Multivariate statistics of the image data allowed delineation of anatomical regions of interest based on their chemical identity. Spectral data extracted from these regions were compared using two different approaches for multivariate statistics, for investigating ALS related lipid and metabolite changes. The results show a significant decrease for cholesterol, triglycerides, and vitamin E in the ventral horn of ALS samples, which is presumably a consequence of motor neuron degeneration. Conversely, the biogenic mediator lipid lysophosphatidylcholine and its fragments were increased in ALS ventral spinal cord, pointing towards neuroinflammatory mechanisms associated with neuronal cell death. ToF-SIMS imaging is a promising approach for chemical histology and pathology for investigating the subcellular mechanisms underlying motor neuron degeneration in amyotrophic lateral sclerosis.
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| 48. |
- Hanrieder, Jörg, 1980, et al.
(författare)
-
Spatial neuroproteomics using imaging mass spectrometry
- 2015
-
Ingår i: Biochimica et Biophysica Acta - Proteins and Proteomics. - : Elsevier BV. - 1878-1454 .- 1570-9639. ; 1854:7, s. 718-731
-
Forskningsöversikt (refereegranskat)abstract
- The nervous system constitutes arguably the most complicated and least understood cellular network in the human body. This consequently manifests itself in the fact that the molecular bases of neurodegenerative diseases remain unknown. The limited understanding of neurobiological mechanisms relates directly to the lack of appropriate bioanalytical technologies that allow highly resolved, sensitive, specific and comprehensive molecular imaging in complex biological matrices. Imaging mass spectrometry (IMS) is an emerging technique for molecular imaging. The technique is characterized by its high chemical specificity allowing comprehensive, spatial protein and peptide profiling in situ. Imaging MS represents therefore a powerful approach for investigation of spatio-temporal protein and peptide regulations in CNS derived tissue and cells. This review aims to provide a concise overview of major developments and applications concerning imaging mass spectrometry based protein and peptide profiling in neurobiological and biomedical research. This article is part of a Special Issue entitled: Neuroproteomics: Applications in Neuroscience and Neurology.
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| 49. |
- Hanrieder, Jörg, 1980, et al.
(författare)
-
Time-of-Flight Secondary Ion Mass Spectrometry Based Molecular Histology of Human Spinal Cord Tissue and Motor Neurons
- 2013
-
Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 85:18, s. 8741-8748
-
Tidskriftsartikel (refereegranskat)abstract
- Secondary ion mass spectrometry is a powerful method for imaging biological samples with high spatial resolution. Whole section time-of-flight-secondary ion mass spectrometry (TOF-SIMS) scans and multivariate data analysis have been performed on the human spinal cord in order to delineate anatomical regions of interest based on their chemical distribution pattern. TOF-SIMS analysis of thoracic spinal cord sections was performed at 5 μm resolution within 2 h. Multivariate image analysis by means of principal component analysis and maximum auto correlation factor analysis resulted in detection of more than 400 m/z peaks that were found to be significantly changed. Here, the results show characteristic biochemical distributions that are well in line with major histological regions, including gray and white matter. As an approach for iterative segmentation, we further evaluated previously outlined regions of interest as identified by multivariate image analysis. Here, further discrimination of the gray matter into ventral, lateral, and dorsal neuroanatomical regions was observed. TOF-SIMS imaging has been carried out at submicrometer resolution obtaining localization and characterization of spinal motor neurons based on their chemical fingerprint, including neurotransmitter precursors that serve as molecular indicators for motor neuron integrity. Thus, TOF-SIMS can be used as an approach for chemical histology and pathology. TOF-SIMS holds immense potential for investigating the subcellular mechanisms underlying spinal cord related diseases including chronic pain and amyotrophic lateral sclerosis.
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| 50. |
- Harreither, Wolfgang, et al.
(författare)
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Carbon Nanotube Fiber Microelectrodes Show a Higher Resistance to Dopamine Fouling
- 2013
-
Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 85:15, s. 7447-7453
-
Tidskriftsartikel (refereegranskat)abstract
- We have compared the properties and resistance to DA fouling of a carbon nanotube fiber (CNTF) microelectrode to a traditional carbon fiber (CF) microelectrode. These two materials show comparable electrochemical activities for outer-sphere and inner-sphere redox reactions. Although the CNTF might have a higher intrinsic RC constant, thus limiting its high-frequency behavior, the CNTF shows a significantly higher durability than the CF in terms of electrode stability. During constant oxidation of 100 mu M DA, the signal measured by the CNTF rnicroelectrode shows a 2-h window over which no decrease in current is observed. Under the same conditions, the current obtained at the CF microelectrode decreases by almost 50%. A model of the fouling process, assuming the formation of growing patches of insulator on the surface, has been compared to the data. This model is found to be in good agreement with our results and indicates a growth rate of the patches in the 0.1-2 nm s(-1) range.
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