For future application to studying regulation of microvascular oxygen delivery, a model is developed for O transport within an idealized volume of tissue, that is perfused by a continuous distribution of capillaries. Considering oxygen diffusion, convection, and consumption, an O-dependent transfer term between the capillaries and tissue is used to extend previous single-compartment approaches to include separate tissue and capillary compartments. The coupled tissue-capillary PDE system is considered for unidirectional capillary flow in z, as a simplified model of O transport in skeletal muscle, and steady-state 2D solutions are obtained using boundary conditions in x that are consistent with two experimental situations of interest. To validate the continuous capillary model, comparisons are made of an exact nonlinear solution (for no flux at x=0) to results of an established discrete capillary model (solved via finite differences) for varying capillary density, O consumption rate, and red blood cell velocity. In addition, comparisons of an approximate linearized solution (for fixed PO at x=0) are made to the corresponding discrete capillary solution. Results of the continuous capillary model are presented for varying inlet O saturation, showing the utility of the new model for studying physiological problems. Numerical solution of the new model for problems with time dependence and complex geometry is expected to be substantially more efficient than for the corresponding discrete capillary problems.
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http://dx.doi.org/10.1016/j.mbs.2020.108535 | DOI Listing |
J Clin Med
December 2024
Lions Eye Institute, Perth, WA 6009, Australia.
Diabetic macular edema (DME) is a significant cause of vision loss. The development of peripheral non-perfusion (PNP) might be associated with the natural course, severity, and treatment of DME. The present study seeks to understand the predictive power of central macular changes and clinico-demographic features for PNP in patients with clinically significant DME.
View Article and Find Full Text PDFMolecules
January 2025
Department of General and Biological Chemistry, Astana Medical University, 010000 Astana, Kazakhstan.
The physicochemical and adsorption properties of granular sorbents based on natural bentonite and modified sorbents based on it have been studied. It was found that modification of natural bentonite with iron (III) polyhydroxocations (mod. 1_Fe_5 GA) and aluminum (III) (mod.
View Article and Find Full Text PDFSci Adv
January 2025
Knight Cancer Precision Biofabrication Hub, Knight Cancer Institute, OHSU, Portland, OR 97201, USA.
A hallmark of chronic and inflammatory diseases is the formation of a fibrotic and stiff extracellular matrix (ECM), typically associated with abnormal, leaky microvascular capillaries. Mechanisms explaining how the microvasculature responds to ECM alterations remain unknown. Here, we used a microphysiological model of capillaries on a chip mimicking the characteristics of healthy or fibrotic collagen to test the hypothesis that perivascular cells mediate the response of vascular capillaries to mechanical and structural changes in the human ECM.
View Article and Find Full Text PDFTransl Vis Sci Technol
January 2025
Yale Cardiovascular Research Center, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA.
Purpose: Alteration of visual acuity in wet age-related macular degeneration (AMD) is mostly driven by vascular endothelial growth factor A (VEGF-A)-induced edema from leaky newly forming blood vessels below the retina layers. To date, all therapies aimed at alleviation of this process have relied on inhibition of VEGF-A activity. Although effective in preventing vascular leak and edema, this approach also leads to the loss of normal vasculature and multiple related side effects.
View Article and Find Full Text PDFNanomaterials (Basel)
December 2024
Department of Civil, Construction, and Environmental Engineering, Iowa State University, Ames, IA 50011, USA.
Multifunctional nanosurfaces receive growing attention due to their versatile properties. Capillary force lithography (CFL) has emerged as a simple and economical method for fabricating these surfaces. In recent works, the authors proposed to leverage the evolution strategies (ES) to modify nanosurface characteristics with CFL to achieve specific functionalities such as frictional, optical, and bactericidal properties.
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