11 research outputs found
Astrocytic Ion Dynamics: Implications for Potassium Buffering and Liquid Flow
We review modeling of astrocyte ion dynamics with a specific focus on the
implications of so-called spatial potassium buffering, where excess potassium
in the extracellular space (ECS) is transported away to prevent pathological
neural spiking. The recently introduced Kirchoff-Nernst-Planck (KNP) scheme for
modeling ion dynamics in astrocytes (and brain tissue in general) is outlined
and used to study such spatial buffering. We next describe how the ion dynamics
of astrocytes may regulate microscopic liquid flow by osmotic effects and how
such microscopic flow can be linked to whole-brain macroscopic flow. We thus
include the key elements in a putative multiscale theory with astrocytes
linking neural activity on a microscopic scale to macroscopic fluid flow.Comment: 27 pages, 7 figure
Entwurf und Implementierung einer Umweltmodell-Datenbank fuer die Roboterprogrammierung
TIB: AC 7197+MF / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Endothelial and Epithelial Expression of Eotaxin-2 (CCL24) in Nasal Polyps
Background: Nasal polyposis is mostly associated with eosinophilia of mucosal tissue. This points to the implication of CC chemokines in nasal eosinophilia. Recently the CC chemokine eotaxin-2 (CCL24) was identifi ed. This study was initiated to localize the cellular source, analyze expression of mRNA, and quantify protein synthesis of CCL24. Methods: Specimens of nasal inferior turbinates from controls and polypous tissue from patients suffering from chronic polypous sinusitis were collected. Furthermore, fi broblasts and epithelial cells were cultured. CCL24 protein was analyzed by immunohistochemistry and ELISA, expression of mRNA by SQ-RT-PCR. Results: CCL24 was observed in endothelial and epithelial cells. Specimens from patients expressed signifi cantly ( 1 2fold) more CCL24 mRNA than controls. Fibroblasts and unstimulated cells did not express CCL24 mRNA. Upon stimulation with TNF- _ , INF- _ , IL-4, or costimulation with TNF- _ and INF- _ CCL24 mRNA was signifi cantly enhanced (3.2â19.6%). In controls, fi broblast, and un- stimulated cells CCL24 protein was below detection limit. Most polyps comprised signifi cant amounts of CCL24 (mean 0.24 ng/mg). TNF- _ , INF- _ or IL-4 induced CCL24 protein (0.1â0.3 ng/ml) in epithelial cells. Costimulation with TNF- _ and IL-4 (0.1â30 and 1â30 ng/ml, respectively) synergistically induced synthesis of CCL24 protein (0.18â0.31 ng/ml). Conclusion: In nasal polyps endothelial and epithelial cells are obviously the main source of CCL24, which was shown for transcription (mRNA) and production (protein) levels and was associated with diseases. Results gave evidence of CLL24- directed migration of cells from inside (the bloodstream) to the epithelial side (mucosa) in eosinophilic infl ammatory diseases, e.g. nasal polyposis