(C) 2009 Elsevier Ltd. All rights reserved.”
“Considering their extremely complicated and hierarchical structure, a long standing question in vascular physio-pathology is how to characterize blood vessels patterns, including which parameters to use. Another question is how to define a pertinent taxonomy, with applications to normal development and to diagnosis and/or staging of diseases.

To address these issues, fractal analysis has been applied by previous investigators to a large variety of healthy or pathologic vascular networks whose fractal dimensions have been sought.

A review of the results selleck inhibitor obtained on healthy vascular networks first shows that no consensus has emerged about whether normal networks must be considered as fractals or not.

Based on a review of previous theoretical work an vascular morphogenesis, we argue that these Nirogacestat clinical trial divergences are the signature of a two-step morphogenesis process, where vascular networks form via progressive penetration of arterial and venous quasi-fractal arborescences into a pre-existing homogeneous capillary mesh. Adopting this perspective, we study the multi-scale behavior of generic patterns (model structures constructed as the superposition of homogeneous meshes and quasi-fractal trees) and of healthy intracortical networks in order to determine the artifactual and true components of their multi-scale behavior. We demonstrate that,

at least in the brain, healthy vascular structures are a superposition of two components: at low scale, a mesh-like capillary component which becomes homogeneous and space-filling over a cut-off length of order of its characteristic length; at larger scale, quasi-fractal branched (tree-like) structures. Such complex structures are consistent with all previous studies on the multi-scale behavior of vascular structures at different scales, resolving the apparent contradiction about their fractal nature.

Consequences regarding the way fractal analysis of vascular networks should be conducted to provide meaningful results are presented. Finally,

consequences for vascular morphogenesis or hemodynamics are discussed, as well as implications in case of pathological conditions, such as cancer. (C) 2009 Elsevier Ltd. All rights reserved.”
“To analyze the small-conductance see more calcium-dependent K+ current observed in dopaminergic neurons of the rat midbrain, we have developed a new dynamic current clamping method that incorporates recording of intracellular Ca2+ levels. As reported earlier, blocking the small-conductance current with apamin shifted the firing modes of dopaminergic neurons and changed the firing rate and spike afterhyperpolarization. We modeled the kinetic properties of the current and assessed the model in a real-time computational system. Here, we show that the spike afterhyperpolarization is regulated by the small-conductance current, an effect that is observed in dopaminergic neurons.