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

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 (3.2–19.6%). 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 (0.1–0.3 ng/ml) in epithelial cells. Costimulation with TNF- _ and IL-4 (0.1–30 and 1–30 ng/ml, respectively) synergistically induced synthesis of CCL24 protein (0.18–0.31 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

How can reasoners simplify database querying (and why haven’t they done it yet)?

The last few decades have seen vast progress in computational reasoning. This has included significant developments in theory, increasing maturity of tools both in performance and usability, and the evolution of standards and benchmarks. The purpose of this article is to reflect on the use of reasoning for rewriting and simplifying relational database queries. We undertake a review of some of the results and reasoning algorithms that have been developed with a motivation from query evaluation, and add to this a look at open problems in the area as well as a critique of prior work from the point of view of practice