62,402 research outputs found
Connexin-dependent neuroglial networking as a new therapeutic target
Astrocytes and neurons dynamically interact during physiological processes, and it is now widely accepted that they are both organized in plastic and tightly regulated networks. Astrocytes are connected through connexin-based gap junction channels, with brain region specificities, and those networks modulate neuronal activities, such as those involved in sleep-wake cycle, cognitive, or sensory functions. Additionally, astrocyte domains have been involved in neurogenesis and neuronal differentiation during development; they participate in the "tripartite synapse" with both pre-synaptic and post-synaptic neurons by tuning down or up neuronal activities through the control of neuronal synaptic strength. Connexin-based hemichannels are also involved in those regulations of neuronal activities, however, this feature will not be considered in the present review. Furthermore, neuronal processes, transmitting electrical signals to chemical synapses, stringently control astroglial connexin expression, and channel functions. Long-range energy trafficking toward neurons through connexin-coupled astrocytes and plasticity of those networks are hence largely dependent on neuronal activity. Such reciprocal interactions between neurons and astrocyte networks involve neurotransmitters, cytokines, endogenous lipids, and peptides released by neurons but also other brain cell types, including microglial and endothelial cells. Over the past 10 years, knowledge about neuroglial interactions has widened and now includes effects of CNS-targeting drugs such as antidepressants, antipsychotics, psychostimulants, or sedatives drugs as potential modulators of connexin function and thus astrocyte networking activity. In physiological situations, neuroglial networking is consequently resulting from a two-way interaction between astrocyte gap junction-mediated networks and those made by neurons. As both cell types are modulated by CNS drugs we postulate that neuroglial networking may emerge as new therapeutic targets in neurological and psychiatric disorders
Tetracycline Actions Relevant to Rosacea Treatment
Until today, the pathogenesis of rosacea is not known in detail. Yet in recent years evidence has been accumulating that rosacea with its common symptoms such as inflammatory lesions, erythema, telangiectasia, phymatous changes, and ocular symptoms is of inflammatory nature. Tetracycline derivatives like doxycycline successfully used in the treatment of skin diseases like acne and rosacea seem to inhibit different inflammatory pathways involved in the pathogenesis by various modes of action. Although data for skin diseases are relatively scanty, the following modes of action of tetracyclines seem to be most relevant for an effective treatment of acne and rosacea: inhibition of matrix metalloproteinases, downmodulation of cytokines, inhibition of cell movement and proliferation, inhibition of granuloma formation, inhibition of reactive oxygen species, nitric oxide, and angiogenesis, whereas inhibition of phospholipase A2 seems to be of lower importance. The role of the saprophytic mite Demodex folliculorum remains to be clarified. Additional studies are necessary to further elucidate how tetracyclines work in rosacea treatment. Copyright (C) 2009 S. Karger AG, Base
Resistance of Liposomal Sunscreen Formulations against Plain Water as well as Salt Water Exposure and Perspiration
The present in vivo investigation using a total of 30 healthy adult volunteers with Fitzpatrick skin type II examines the persistent efficacy of sunscreens using liposomal suspensions as the vehicle. Based on the COLIPA guidelines, the protective effect of a single application of 4 different liposomal sunscreen formulations (sun protection factors, SPFs: 50+, 30,25 and 15) against sunburn at the recommended amount of 2 mg/cm(2) was determined after exposure of the skin to plain water and salt water and after profuse perspiration. Under the influence of plain water, salt water and sweating, the SPF values of sunscreen 1 (labeled SPF of 50+) were reduced only marginally to 97, 96 and 99%, respectively, those of sunscreen 2 (labeled SPF of 30) to 97, 96 and 99%, respectively, those of sunscreen 3 (labeled SPE of 25) to 90, 83 and 91%, respectively, and those of sunscreen 4 (labeled SPF of 15) to 96, 96 and 95%, respectively. This set of data shows that despite plain water and salt water immersion or profuse sweating, the liposomal sunscreen formulation may deliver a long-lasting protective effect in everyday situations encountered by outdoor workers or during leisure activities. Copyright (C) 2010 S. Karger AG, Base
Enriched Lawvere Theories for Operational Semantics
Enriched Lawvere theories are a generalization of Lawvere theories that allow
us to describe the operational semantics of formal systems. For example, a
graph enriched Lawvere theory describes structures that have a graph of
operations of each arity, where the vertices are operations and the edges are
rewrites between operations. Enriched theories can be used to equip systems
with operational semantics, and maps between enriching categories can serve to
translate between different forms of operational and denotational semantics.
The Grothendieck construction lets us study all models of all enriched theories
in all contexts in a single category. We illustrate these ideas with the
SKI-combinator calculus, a variable-free version of the lambda calculus.Comment: In Proceedings ACT 2019, arXiv:2009.0633
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