Search

Your search keyword '"Meissner R"' showing total 35 results
Start Over Author "Meissner R" Publisher wiley
35 results on '"Meissner R"'

34. Positive and negative ions of the amino acid histidine formed in low-energy electron collisions.

Author

Meißner R, Feketeová L, Bayer A, Postler J, Limão-Vieira P, and Denifl S

Subjects
Electrons, Heating, Ions chemistry, Mass Spectrometry, Models, Chemical, Molecular Conformation, Quantum Theory, Thermodynamics, Histidine chemistry
Abstract

Histidine is an aromatic amino acid crucial for the biological functioning of proteins and enzymes. When biological matter is exposed to ionising radiation, highly energetic particles interact with the surrounding tissue which leads to efficient formation of low-energy electrons. In the present study, the interaction of low-energy electrons with gas-phase histidine is studied at a molecular level in order to extend the knowledge of electron-induced reactions with amino acids. We report both on the formation of positive ions formed by electron ionisation and negative ions induced by electron attachment. The experimental data were complemented by quantum chemical calculations. Specifically, the free energies for possible fragmentation reactions were derived for the τ and the π tautomer of histidine to get insight into the structures of the formed ions and the corresponding neutrals. We report the experimental ionisation energy of (8.48 ± 0.03) eV for histidine which is in good agreement with the calculated vertical ionisation energy. In the case of negative ions, the dehydrogenated parent anion is the anion with the highest mass observed upon dissociative electron attachment. The comparison of experimental and computational results was also performed in view of a possible thermal decomposition of histidine during the experiments, since the sample was sublimated in the experiment by resistive heating of an oven. Overall, the present study demonstrates the effects of electrons as secondary particles in the chemical degradation of histidine. The reactions induced by those electrons differ when comparing positive and negative ion formation. While for negative ions, simple bond cleav ages prevail, the observed fragment cations exhibit partly restructuring of the molecule during the dissociation process., (© 2019 The Authors. Journal of Mass Spectrometry published by John Wiley & Sons Ltd.)

Published
2019
Full Text
View/download PDF

35. Co-pathological connected primary neurons in a microfluidic device for Alzheimer studies.

Author

Kunze A, Meissner R, Brando S, and Renaud P

Subjects
Alzheimer Disease metabolism, Animals, Cells, Cultured, Cerebral Cortex metabolism, Cerebral Cortex pathology, Cytological Techniques methods, Nerve Degeneration pathology, Neurons metabolism, Okadaic Acid, Phosphorylation, Rats, Rats, Wistar, tau Proteins metabolism, Alzheimer Disease pathology, Cytological Techniques instrumentation, Microfluidic Analytical Techniques instrumentation, Models, Neurological, Neurons pathology
Abstract

This communication presents a novel experimental model for Alzheimer studies, where connected primary neurons were set into subtend, co-pathological states. Cortical neurons were cultured in two separated cell compartments in a microfluidic device. A neurite network was generated in a main channel through the neurite outgrowth from both cell compartments. A gradient of okadaic acid (OA) is generated over this neurite network by perfusion. OA is a phosphatase inhibitor that induces hyperphosphorylation of Tau proteins, a major hallmark in Alzheimer disease. The local OA treatment resulted in a connected "diseased" and "healthy" cell population. Anti-phosphorylated tau (Ser262) staining confirmed different states of phosphorylated Tau proteins, and synapthophysin staining the connection of "healthy" and "diseased" cells. Here, we present a novel in vitro model that opens the possibility to study cellular and molecular propagation mechanisms in neurodegeneration, in Tauopathies (as e.g., in Alzheimer), as well as simultaneous drug effects on connected healthy and diseased cell populations., (Copyright © 2011 Wiley Periodicals, Inc.)

Published
2011
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results