scholarly journals Brain solute transport is more rapid in periarterial than perivenous spaces

2021 ◽  
Author(s):  
Vegard Vinje ◽  
Erik Nicolaas Theodorus Petrus Bakker ◽  
Marie E Rognes
Keyword(s):  
Fluid Flow ◽  
Solute Transport ◽  
Interstitial Fluid ◽  
Computational Modelling ◽  
Perivascular Spaces ◽  
Tracer Transport ◽  
Csf Flow ◽  
Arrival Times ◽  
Open Question ◽  
Rapid Appearance

Background: Perivascular fluid flow, of cerebrospinal or interstitial fluid in spaces surrounding brain blood vessels, is recognized as a key component underlying brain transport and clearance. An important open question is how and to what extent differences in vessel type or geometry affect perivascular fluid flow and transport. Methods: Using computational modelling in both idealized and image-based geometries, we study and compare fluid flow and solute transport in pial (surface) periarterial and perivenous spaces. Results: Our findings demonstrate that differences in geometry between arterial and venous pial perivascular spaces (PVSs) lead to higher net CSF flow, more rapid tracer transport and earlier arrival times of injected tracers in periarterial spaces compared to perivenous spaces. Conclusions: These findings can explain the experimentally observed rapid appearance of tracers around arteries, and the delayed appearance around veins without the need of a circulation through the parenchyma, but rather by direct transport along the PVSs.

scholarly journals Brain solute transport is more rapid in periarterial than perivenous spaces

2021 ◽  
Author(s):  
Vegard Vinje ◽  
Erik Nicolaas Theodorus Petrus Bakker ◽  
Marie E Rognes
Keyword(s):  
Fluid Flow ◽  
Solute Transport ◽  
Interstitial Fluid ◽  
Computational Modelling ◽  
Perivascular Spaces ◽  
Tracer Transport ◽  
Csf Flow ◽  
Arrival Times ◽  
Open Question ◽  
Rapid Appearance

Abstract Background: Perivascular fluid flow, of cerebrospinal or interstitial fluid in spaces surrounding brain blood vessels, is recognized as a key component underlying brain transport and clearance. An important open question is how and to what extent differences in vessel type or geometry affect perivascular fluid flow and transport. Methods: Using computational modelling in both idealized and image-based geometries, we study and compare fluid flow and solute transport in pial (surface) periarterial and perivenous spaces. Results: Our findings demonstrate that differences in geometry between arterial and venous pial perivascular spaces (PVSs) lead to higher net CSF flow, more rapid tracer transport and earlier arrival times of injected tracers in periarterial spaces compared to perivenous spaces. Conclusions: These findings can explain the experimentally observed rapid appearance of tracers around arteries, and the delayed appearance around veins without the need of a circulation through the parenchyma, but rather by direct transport along the PVSs.

scholarly journals Brain solute transport is more rapid in periarterial than perivenous spaces

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Vegard Vinje ◽  
Erik N. T. P. Bakker ◽  
Marie E. Rognes
Keyword(s):  
Fluid Flow ◽  
Solute Transport ◽  
Computational Modelling ◽  
Perivascular Spaces ◽  
Tracer Transport ◽  
Csf Flow ◽  
Pial Surface ◽  
Arrival Times ◽  
Open Question ◽  
Rapid Appearance

AbstractFluid flow in perivascular spaces is recognized as a key component underlying brain transport and clearance. An important open question is how and to what extent differences in vessel type or geometry affect perivascular fluid flow and transport. Using computational modelling in both idealized and image-based geometries, we study and compare fluid flow and solute transport in pial (surface) periarterial and perivenous spaces. Our findings demonstrate that differences in geometry between arterial and venous pial perivascular spaces (PVSs) lead to higher net CSF flow, more rapid tracer transport and earlier arrival times of injected tracers in periarterial spaces compared to perivenous spaces. These findings can explain the experimentally observed rapid appearance of tracers around arteries, and the delayed appearance around veins without the need of a circulation through the parenchyma, but rather by direct transport along the PVSs.

scholarly journals Mathematical modelling of fluid flow and solute transport to define operating parameters for in vitro perfusion cell culture systems

2020 ◽  
Vol 10 (2) ◽  
pp. 20190045 ◽  
Author(s):  
Lauren Hyndman ◽  
Sean McKee ◽  
Nigel J. Mottram ◽  
Bhumika Singh ◽  
Steven D. Webb ◽  
...  
Keyword(s):  
Cell Culture ◽  
Fluid Flow ◽  
Mathematical Modelling ◽  
Solute Transport ◽  
Computational Modelling ◽  
Operating Parameters ◽  
Perfusion Cell Culture ◽  
Culture Systems ◽  
Cell Culture Systems

In recent years, there has been a move away from the use of static in vitro two-dimensional cell culture models for testing the chemical safety and efficacy of drugs. Such models are increasingly being replaced by more physiologically relevant cell culture systems featuring dynamic flow and/or three-dimensional structures of cells. While it is acknowledged that such systems provide a more realistic environment within which to test drugs, progress is being hindered by a lack of understanding of the physical and chemical environment that the cells are exposed to. Mathematical and computational modelling may be exploited in this regard to unravel the dependency of the cell response on spatio-temporal differences in chemical and mechanical cues, thereby assisting with the understanding and design of these systems. In this paper, we present a mathematical modelling framework that characterizes the fluid flow and solute transport in perfusion bioreactors featuring an inlet and an outlet. To demonstrate the utility of our model, we simulated the fluid dynamics and solute concentration profiles for a variety of different flow rates, inlet solute concentrations and cell types within a specific commercial bioreactor chamber. Our subsequent analysis has elucidated the basic relationship between inlet flow rate and cell surface flow speed, shear stress and solute concentrations, allowing us to derive simple but useful relationships that enable prediction of the behaviour of the system under a variety of experimental conditions, prior to experimentation. We describe how the model may used by experimentalists to define operating parameters for their particular perfusion cell culture systems and highlight some operating conditions that should be avoided. Finally, we critically comment on the limitations of mathematical and computational modelling in this field, and the challenges associated with the adoption of such methods.

The influence of the relative timing of arterial and subarachnoid space pulse waves on spinal perivascular cerebrospinal fluid flow as a possible factor in syrinx development

2010 ◽  
Vol 112 (4) ◽  
pp. 808-813 ◽  
Author(s):  
Lynne E. Bilston ◽  
Marcus A. Stoodley ◽  
David F. Fletcher
Keyword(s):  
Spinal Cord ◽  
Fluid Flow ◽  
Subarachnoid Space ◽  
Pulse Wave ◽  
Driving Forces ◽  
Fluid Pressure ◽  
Perivascular Spaces ◽  
Relative Timing ◽  
Csf Flow ◽  
Cerebrospinal Fluid Flow

Object The mechanisms of syringomyelia have long puzzled neurosurgeons and researchers alike due to difficulties in identifying the driving forces behind fluid flow into a syrinx, apparently against a pressure gradient between the spinal cord and the subarachnoid space (SAS). Recently, the synchronization between CSF flow and the cardiac cycle has been postulated to affect fluid flow in the spinal cord. This study aims to determine the effect of changes in the timing of SAS pressure on perivascular flow into the spinal cord. Methods This study uses a computational fluid dynamics model to investigate whether the relative timing of a spinal artery cardiovascular pulse wave and fluid pressure in the spinal SAS can influence CSF flow in the perivascular spaces. Results The results show that the mass flow rate of CSF through a model periarterial space is strongly influenced by the relative timing of the arterial pulse wave and the SAS pressure. Conclusions These findings suggest that factors that might alter the timing of the pulse wave or the fluid flow in the SAS could potentially affect fluid flow into a syrinx.

scholarly journals Effect of tumor shape, size, and tissue transport properties on drug delivery to solid tumors

2021 ◽  
Author(s):  
Mostafa Sefidgar ◽  
M Soltani ◽  
Kaamran Raahemifar ◽  
Hossein Bazmara ◽  
Seyed Mojtaba Mousavi Nayinian ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Fluid Flow ◽  
Solute Transport ◽  
Solid Tumor ◽  
Drug Concentration ◽  
Interstitial Fluid ◽  
Initial Conditions ◽  
Surrounding Tissue ◽  
Governing Equations ◽  
Tumor Shape

Background The computational methods provide condition for investigation related to the process of drug delivery, such as convection and diffusion of drug in extracellular matrices, drug extravasation from microvessels or to lymphatic vessels. The information of this process clarifies the mechanisms of drug delivery from the injection site to absorption by a solid tumor. In this study, an advanced numerical method is used to solve fluid flow and solute transport equations simultaneously to investigate the effect of tumor shape and size on drug delivery to solid tumor. Methods The advanced mathematical model used in our previous work is further developed by adding solute transport equation to the governing equations. After applying appropriate boundary and initial conditions on tumor and surrounding tissue geometry, the element-based finite volume method is used for solving governing equations of drug delivery in solid tumor. Also, the effects of size and shape of tumor and some of tissue transport parameters such as effective pressure and hydraulic conductivity on interstitial fluid flow and drug delivery are investigated. Results Sensitivity analysis shows that drug delivery in prolate shape is significantly better than other tumor shapes. Considering size effect, increasing tumor size decreases drug concentration in interstitial fluid. This study shows that dependency of drug concentration in interstitial fluid to osmotic and intravascular pressure is negligible. Conclusions This study shows that among diffusion and convection mechanisms of drug transport, diffusion is dominant in most different tumor shapes and sizes. In tumors in which the convection has considerable effect, the drug concentration is larger than that of other tumors at the same time post injection.

scholarly journals Effect of tumor shape, size, and tissue transport properties on drug delivery to solid tumors

2021 ◽  
Author(s):  
Mostafa Sefidgar ◽  
M Soltani ◽  
Kaamran Raahemifar ◽  
Hossein Bazmara ◽  
Seyed Mojtaba Mousavi Nayinian ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Fluid Flow ◽  
Solute Transport ◽  
Solid Tumor ◽  
Drug Concentration ◽  
Interstitial Fluid ◽  
Initial Conditions ◽  
Surrounding Tissue ◽  
Governing Equations ◽  
Tumor Shape

Background The computational methods provide condition for investigation related to the process of drug delivery, such as convection and diffusion of drug in extracellular matrices, drug extravasation from microvessels or to lymphatic vessels. The information of this process clarifies the mechanisms of drug delivery from the injection site to absorption by a solid tumor. In this study, an advanced numerical method is used to solve fluid flow and solute transport equations simultaneously to investigate the effect of tumor shape and size on drug delivery to solid tumor. Methods The advanced mathematical model used in our previous work is further developed by adding solute transport equation to the governing equations. After applying appropriate boundary and initial conditions on tumor and surrounding tissue geometry, the element-based finite volume method is used for solving governing equations of drug delivery in solid tumor. Also, the effects of size and shape of tumor and some of tissue transport parameters such as effective pressure and hydraulic conductivity on interstitial fluid flow and drug delivery are investigated. Results Sensitivity analysis shows that drug delivery in prolate shape is significantly better than other tumor shapes. Considering size effect, increasing tumor size decreases drug concentration in interstitial fluid. This study shows that dependency of drug concentration in interstitial fluid to osmotic and intravascular pressure is negligible. Conclusions This study shows that among diffusion and convection mechanisms of drug transport, diffusion is dominant in most different tumor shapes and sizes. In tumors in which the convection has considerable effect, the drug concentration is larger than that of other tumors at the same time post injection.

scholarly journals Near-surface real-time seismic imaging using parsimonious interferometry

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sherif M. Hanafy ◽  
Hussein Hoteit ◽  
Jing Li ◽  
Gerard T. Schuster
Keyword(s):  
Fluid Flow ◽  
Real Time ◽  
Temporal Resolution ◽  
Seismic Imaging ◽  
Time Lapse ◽  
Rock Properties ◽  
Recording Time ◽  
Near Surface ◽  
Arrival Times ◽  
Order Of Magnitude

AbstractResults are presented for real-time seismic imaging of subsurface fluid flow by parsimonious refraction and surface-wave interferometry. Each subsurface velocity image inverted from time-lapse seismic data only requires several minutes of recording time, which is less than the time-scale of the fluid-induced changes in the rock properties. In this sense this is real-time imaging. The images are P-velocity tomograms inverted from the first-arrival times and the S-velocity tomograms inverted from dispersion curves. Compared to conventional seismic imaging, parsimonious interferometry reduces the recording time and increases the temporal resolution of time-lapse seismic images by more than an order-of-magnitude. In our seismic experiment, we recorded 90 sparse data sets over 4.5 h while injecting 12-tons of water into a sand dune. Results show that the percolation of water is mostly along layered boundaries down to a depth of a few meters, which is consistent with our 3D computational fluid flow simulations and laboratory experiments. The significance of parsimonious interferometry is that it provides more than an order-of-magnitude increase of temporal resolution in time-lapse seismic imaging. We believe that real-time seismic imaging will have important applications for non-destructive characterization in environmental, biomedical, and subsurface imaging.

scholarly journals On the characterization of interstitial fluid flow in the skeletal muscle endomysium

2020 ◽  
Vol 102 ◽  
pp. 103504 ◽  
Author(s):  
Qiuyun Wang ◽  
Shaopeng Pei ◽  
X. Lucas Lu ◽  
Liyun Wang ◽  
Qianhong Wu
Keyword(s):  
Skeletal Muscle ◽  
Fluid Flow ◽  
Interstitial Fluid ◽  
Interstitial Fluid Flow

Drainage of cerebral interstitial fluid into deep cervical lymph of the rabbit

1981 ◽  
Vol 240 (4) ◽  
pp. F329-F336 ◽  
Author(s):  
M. W. Bradbury ◽  
H. F. Cserr ◽  
R. J. Westrop
Keyword(s):  
Cerebrospinal Fluid ◽  
Caudate Nucleus ◽  
Subarachnoid Space ◽  
Interstitial Fluid ◽  
Bulk Flow ◽  
Perivascular Spaces ◽  
Csf Analysis ◽  
Intraventricular Injections ◽  
Intracerebral Microinjection ◽  
Do So

Lymph from the jugular lymph trunks of anesthetized rabbits has been continuously collected and radioiodinated albumin (RISA) therein estimated after microinjection of 1 microliter of 131I-albumin into the caudate nucleus, after single intraventricular injections, and during intraventricular infusions. Comparison of lymph at 7 and 25 h after intracerebral microinjection with efflux of radioactivity from whole brain suggests that about 50% of cleared radioactivity goes through lymph. Concentrations, normalized to cerebrospinal fluid (CSF), were much higher in lymph and retropharyngeal nodes after brain injection than after CSF injection or infusion. Also after brain injection, lymph and nodes contained more activity on injected side in contrast to lack of laterality after CSF administration. Calculation suggests that less than 30% of RISA cleared from brain can do so via a pool of well-mixed CSF. Analysis of tissues is compatible with much RISA draining by bulk flow via cerebral perivascular spaces plus passage from subarachnoid space of olfactory lobes into submucous spaces of nose and thus to lymph.

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