The Fluid Shear Stress Distribution on the Membrane of Leukocytes in the Microcirculation

2003 ◽  
Vol 125 (5) ◽  
pp. 628-638 ◽  
Author(s):  
Masako Sugihara-Seki ◽  
Geert W. Schmid-Scho¨nbein
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Fluid Shear Stress ◽  
Cell Function ◽  
Shear Stress Distribution ◽  
Shear Stresses ◽  
Fluid Shear ◽  
Stress Gradients ◽  
Freely Suspended ◽  
Microvessel Wall

Recent in-vivo and in-vitro evidence indicates that fluid shear stress on the membrane of leukocytes has a powerful control over several aspects of their cell function. This evidence raises a question about the magnitude of the fluid shear stress on leukocytes in the circulation. The flow of plasma on the surface of a leukocyte at a very low Reynolds number is governed by the Stokes equation for the motion of a Newtonian fluid. We numerically estimated the distribution of fluid shear stress on a leukocyte membrane in a microvessel for the cases when the leukocyte is freely suspended, as well as rolling along or attached to a microvessel wall. The results indicate that the fluid shear stress distribution on the leukocyte membrane is nonuniform with a sharp increase when the leukocyte makes membrane attachment to the microvessel wall. In a microvessel (10 μm diameter), the fluid shear stress on the membrane of a freely suspended leukocyte (8 μm diameter) is estimated to be several times larger than the wall shear stress exerted by the undisturbed Poiseuille flow, and increases on an adherent leukocyte up to ten times. High temporal stress gradients are present in freely suspended leukocytes in shear flow due to cell rotation, which are proportional to the local shear rate. In comparison, the temporal stress gradients are reduced on the membrane of leukocytes that are rolling or firmly adhered to the endothelium. High temporal gradients of shear stress are also present on the endothelial wall. At a plasma viscosity of 1 cPoise, the peak shear stresses for suspended and adherent leukocytes are of the order of 10 dyn/cm2 and 100 dyn/cm2, respectively.

scholarly journals Assessing Machine Learning versus a Mathematical Model to Estimate the Transverse Shear Stress Distribution in a Rectangular Channel

Mathematics ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 596
Author(s):  
Babak Lashkar-Ara ◽  
Niloofar Kalantari ◽  
Zohreh Sheikh Khozani ◽  
Amir Mosavi
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Fuzzy Inference ◽  
Rectangular Channel ◽  
Tsallis Entropy ◽  
Shear Stress Distribution ◽  
Data Series ◽  
Shear Stresses ◽  
Inference System ◽  
Aspect Ratios

One of the most important subjects of hydraulic engineering is the reliable estimation of the transverse distribution in the rectangular channel of bed and wall shear stresses. This study makes use of the Tsallis entropy, genetic programming (GP) and adaptive neuro-fuzzy inference system (ANFIS) methods to assess the shear stress distribution (SSD) in the rectangular channel. To evaluate the results of the Tsallis entropy, GP and ANFIS models, laboratory observations were used in which shear stress was measured using an optimized Preston tube. This is then used to measure the SSD in various aspect ratios in the rectangular channel. To investigate the shear stress percentage, 10 data series with a total of 112 different data for were used. The results of the sensitivity analysis show that the most influential parameter for the SSD in smooth rectangular channel is the dimensionless parameter B/H, Where the transverse coordinate is B, and the flow depth is H. With the parameters (b/B), (B/H) for the bed and (z/H), (B/H) for the wall as inputs, the modeling of the GP was better than the other one. Based on the analysis, it can be concluded that the use of GP and ANFIS algorithms is more effective in estimating shear stress in smooth rectangular channels than the Tsallis entropy-based equations.

scholarly journals Shear Stress Distribution in the Opening Chords of Hybrid R/C T-Beams with Opening

2018 ◽  
Vol 147 ◽  
pp. 01005
Author(s):  
Jonie Tanijaya
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Shear Force ◽  
Maximum Shear Stress ◽  
Shear Stress Distribution ◽  
Shear Stresses ◽  
Web Openings ◽  
The Right ◽  
Lower Corner ◽  
T Beam

This study is carried out to evaluate the potential of three hybrid T-beams with web openings theoretical shear stresses distribution. The shear stresses at the opening edges were plotted at the working stage, yielding stage and collapse stage for these three tested beams. The available experimental results from the previous research was compared to the finite element results as well as the developed analytical. The shear stress distribution at the middle of the top and bottom chords of the opening in pure bending region are zero. At the upper and lower corners of the opening occurs the maximum shear stresses. The maximum shear stress occurs at the right lower corner chord at the high moment edge and at the left upper corner chord at the low moment edge in beams with openings at high shear and high flexural – shear region. Furthermore, an extensive parametric study is performed on these beams to find the distributing ratio of the shear force between the opening chords. The shear force at an opening in hybrid R/C T-beam is carried by the top and bottom chords of the opening according to the area – moment of inertia root ratio with the correction factor 0.70.

Effects of Fluid Shear Stress on Endothelial Cell Invasion Into Three-Dimensional Matrices

2007 ◽  
Author(s):  
Hojin Kang ◽  
Kayla J. Bayless ◽  
Roland Kaunas
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Endothelial Cell ◽  
Cell Invasion ◽  
Fluid Shear Stress ◽  
Vascular Endothelial Cells ◽  
Umbilical Vein ◽  
Shear Stresses ◽  
Collagen Gels ◽  
Fluid Shear

We have previously developed a cell culture model to study the effects of angiogenic factors, such as sphingosine-1-phosphate (S1P), on the invasion of endothelial cells into the underlying extracellular matrix. In addition to biochemical stimuli, vascular endothelial cells are subjected to fluid shear stress due to blood flow. The present study is aimed at determining the effects of fluid shear stress on endothelial cell invasion into collagen gels. A device was constructed to apply well-defined fluid shear stresses to confluent human umbilical vein endothelial cells (HUVECs) seeded on collagen gels. Fluid shear stress induced significant increases in cell invasion with a maximal induction at ∼5 dyn/cm2. These results provide evidence that fluid shear stress is a significant stimulus for endothelial cell invasion and may play a role in regulating angiogenesis.

scholarly journals Fluid Shear Stress Modulation of Gene Expression in Endothelial Cells

Physiology ◽  
1998 ◽  
Vol 13 (5) ◽  
pp. 241-246 ◽  
Author(s):  
Martin Braddock ◽  
Jean-Luc Schwachtgen ◽  
Parul Houston ◽  
Marion C. Dickson ◽  
Michael J. Lee ◽  
...  
Keyword(s):  
Fluid Shear Stress ◽  
Cell Function ◽  
Shear Stresses ◽  
Biological Processes ◽  
Fluid Shear ◽  
Endothelial Cell Function ◽  
Complex Interactions ◽  
Expression Of Genes ◽  
Modulation Of Gene Expression ◽  
Flowing Blood

The vascular endothelium, lining the blood vessel wall, is constantly exposed to wall shear stresses generated by flowing blood. Gene regulation, critical for endothelial cell function, depends on complex interactions at the promoter level and utilizes overlapping signal transduction cascades to activate the expression of genes involved in many biological processes.

Numerical Analysis of Shear Stress on Adhesive Joint between FRP and Steel Structure in Civil Engineering

2012 ◽  
Vol 568 ◽  
pp. 216-221
Author(s):  
Shu Kuan Zhang ◽  
Pei Yan Huang ◽  
Hao Zhou ◽  
Chuan Yu Zhao
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Adhesive Joint ◽  
Civil Engineering ◽  
Great Influence ◽  
Steel Structure ◽  
High Strength ◽  
Shear Stress Distribution ◽  
Shear Stresses ◽  
Accurate Analysis

Fiber reinforced polymer (FRP) is widely applied in the concrete and steel structure reinforcement field because of its high strength and convenient constructability in civil engineering. The adhesive joint is the weakness of the reinforced structure, but with the complicated stress distribution for analytic method. Numerical method provides the best solution to the further analysis. In this paper, a finite element method (FEM) of double lap joint model was established with ANSYS to investigate the shear stress in the adhesive joint of the reinforced structure, the shear stresses were analyzed in detail in both length and thickness direction in civil engineering. The results show that, 1) the FEM calculation results of shear stress of adhesive and the theoretical calculation values are consistent within the main part of the adhesive; 2) FEM is the effective method to further study the shear stress distribution of the adhesive, meshing size has great influence on the results of calculation; 3) to obtain more accurate analysis of shear stress distribution, the non-linear characteristics of the adhesive should be considered

scholarly journals High Fluid Shear Stress and Spatial Shear Stress Gradients Affect Endothelial Proliferation, Survival, and Alignment

2011 ◽  
Vol 39 (6) ◽  
pp. 1620-1631 ◽  
Author(s):  
Jennifer M. Dolan ◽  
Hui Meng ◽  
Sukhjinder Singh ◽  
Rocco Paluch ◽  
John Kolega
Keyword(s):  
Shear Stress ◽  
Fluid Shear Stress ◽  
Fluid Shear ◽  
Stress Gradients ◽  
Endothelial Proliferation ◽  
High Fluid

scholarly journals Shear-induced platelet aggregation can be mediated by vWF released from platelets, as well as by exogenous large or unusually large vWF multimers, requires adenosine diphosphate, and is resistant to aspirin

Blood ◽  
1988 ◽  
Vol 71 (5) ◽  
pp. 1366-1374 ◽  
Author(s):  
JL Moake ◽  
NA Turner ◽  
NA Stathopoulos ◽  
L Nolasco ◽  
JD Hellums
Keyword(s):  
Shear Stress ◽  
Platelet Aggregation ◽  
Fluid Shear Stress ◽  
Thrombus Formation ◽  
Adenosine Diphosphate ◽  
Shear Stresses ◽  
Fluid Shear ◽  
Von Willebrand ◽  
Induced Aggregation

Abstract Fluid shear stress in arteries and arterioles partially obstructed by atherosclerosis or spasm may exceed the normal time-average level of 20 dyne/cm2. In vitro, at fluid shear stresses of 30 to 60 dyne/cm2 applied for 30 seconds, platelet aggregation occurs. At these shear stresses, either large or unusually large von Willebrand factor (vWF) multimers in the suspending fluid exogenous to the platelets mediates aggregation. Adenosine diphosphate (ADP) is also required and, in these experiments, was released from the platelets subjected to shear stress. At 120 dyne/cm2, the release of endogenous platelet vWF multimers can substitute for exogenous large or unusually large vWF forms in mediating aggregation. Endogenous released platelet vWF forms, as well as exogenous large or unusually large vWF multimers, must bind to both glycoproteins Ib and the IIb/IIIa complex to produce aggregation. Shear- induced aggregation is the result of shear stress alteration of platelet surfaces, rather than of shear effects on vWF multimers. It is mediated by either large plasma-type vWF multimers, endogenous released platelet vWF forms, or unusually large vWF multimers derived from endothelial cells, requires ADP, and is not inhibited significantly by aspirin. This type of aggregation may be important in platelet thrombus formation within narrowed arterial vessels, and may explain the limited therapeutic utility of aspirin in arterial thrombosis.

Development of Microfluidic Chips to Study the Effects of Shear Stress on Cell Functions

2010 ◽  
Author(s):  
Jianbin Wang ◽  
Jinseok Heo ◽  
Susan Z. Hua
Keyword(s):  
Shear Stress ◽  
Fluid Shear Stress ◽  
Cellular Systems ◽  
Shear Stresses ◽  
Microfluidic Chips ◽  
Fluid Shear ◽  
Cell Functions ◽  
Culture Cells ◽  
Wide Range ◽  
On Chip

Fluid shear stress has profound effect on many cell functions, including proliferation, migration, transport, and gene expression. Cellular systems such as endothelial cells in heart artery and epithelial cells in kidney tubule are constantly subject to fluid flow. We have developed a series of microfluidic chips that generate a wide range and modes of shear stresses within a perfusion chamber, enabling us to culture cells on chip and examine the effects of shear stress on cell growth and cell functions.

Experimental Technique of Measuring Dynamic Fluid Shear Stress on the Aortic Surface of the Aortic Valve Leaflet

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Choon Hwai Yap ◽  
Neelakantan Saikrishnan ◽  
Gowthami Tamilselvan ◽  
Ajit P. Yoganathan
Keyword(s):  
Shear Stress ◽  
Aortic Valve ◽  
Steady Flow ◽  
Fluid Shear Stress ◽  
Shear Stresses ◽  
Straight Tube ◽  
Valve Leaflet ◽  
Fluid Shear ◽  
Valve Model

Aortic valve (AV) calcification is a highly prevalent disease with serious impact on mortality and morbidity. The exact cause and mechanism of the progression of AV calcification is unknown, although mechanical forces have been known to play a role. It is thus important to characterize the mechanical environment of the AV. In the current study, we establish a methodology of measuring shear stresses experienced by the aortic surface of the AV leaflets using an in vitro valve model and adapting the laser Doppler velocimetry (LDV) technique. The valve model was constructed from a fresh porcine aortic valve, which was trimmed and sutured onto a plastic stented ring, and inserted into an idealized three-lobed sinus acrylic chamber. Valve leaflet location was measured by obtaining the location of highest back-scattered LDV laser light intensity. The technique of performing LDV measurements near to biological surfaces as well as the leaflet locating technique was first validated in two phantom flow systems: (1) steady flow within a straight tube with AV leaflet adhered to the wall, and (2) steady flow within the actual valve model. Dynamic shear stresses were then obtained by applying the techniques on the valve model in a physiologic pulsatile flow loop. Results show that aortic surface shear stresses are low during early systole (<5dyn/cm2) but elevated to its peak during mid to late systole at about 18–20 dyn/cm2. Low magnitude shear stress (<5dyn/cm2) was observed during early diastole and dissipated to zero over the diastolic duration. Systolic shear stress was observed to elevate only with the formation of sinus vortex flow. The presented technique can also be used on other in vitro valve models such as congenitally geometrically malformed valves, or to investigate effects of hemodynamics on valve shear stress. Shear stress data can be used for further experiments investigating effects of fluid shear stress on valve biology, for conditioning tissue engineered AV, and to validate numerical simulations.

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