Growth and Stability of Thrombi in Flowing Citrated Blood: Assessment of Platelet-Surface Interactions with Computer-Assisted Morphometry

1988 ◽  
Vol 60 (03) ◽  
pp. 392-398 ◽  
Author(s):  
Kjell S Sakariassen ◽  
Herbert Kuhn ◽  
Reto Muggli ◽  
Hans R Baumgartner
Keyword(s):  
Blood Flow ◽  
Platelet Adhesion ◽  
Three Dimensional ◽  
Blood Stream ◽  
Three Dimensions ◽  
Computer Assisted ◽  
Platelet Surface ◽  
Shear Rates ◽  
Perfusion Studies ◽  
En Face

SummaryThe differential quantitation of platelet deposition in perfusion studies is a major problem. We report on methods to prepare semithin sections of platelet deposits on collagen coated on glass and plastic cover slips, to study growth and stability of thrombi in three dimensions, and the development of a computer-assisted differential quantitation of platelet-collagen interactions. The interactions were quantified as percentage of the surface covered with platelets (platelet adhesion), thrombus height, thrombus density and thrombus area per unit sectional length, respectively.Cover slips coated with fibrillar equine collagen in parallelplate perfusion chambers were exposed to flowing citrated blood at shear rates ranging from 200 to 2,600 s−1. Thrombi, partially enmeshed in the collagen meshwork, prevailed on the surface at all shear rates. Maximal platelet adhesion and thrombus density were seen at >5 μg/cm2 collagen, while thrombus area and height were maximal at >10 μg/cm2. The volume of the thrombi appeared correlated to the number of deposited platelets (r = 0.92). En face preparations showed deposits of platelet islands which grew in diameter with time, particularly in the direction of the blood flow, becoming progressively confluent. Sections cut parallel to the direction of the blood stream indicated that this growth pattern was at least partially caused by thrombi bent in the direction of the blood flow. This view is consistent with data from corresponding sections cut perpendicular to the direction of the blood flow showing that the initial thrombus growth at 2 min is isotropic, while anisotropic growth, characterized with decreased growth in height, is observed at 5 and 10 min.Our three-dimensional analysis suggests that the growth occurs mainly in height, and that blood shear forces may bend the thrombi toward the surface resulting in platelet thrombi preferentially elongated in the direction of the blood flow.

scholarly journals Exemplification of Tomographic Method to Evaluate the Quality of Welded Joints Made from EN 5754-H22 Alloy

2016 ◽  
Vol 39 (1) ◽  
pp. 65-78
Author(s):  
Józef Błachnio ◽  
Artur Kułaszka ◽  
Marek Chalimoniuk ◽  
Piotr Woźny
Keyword(s):  
Welded Joints ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Computer Assisted ◽  
Ct Scanner ◽  
Computer Assisted Tomography ◽  
Tomographic Method ◽  
Industrial Ct ◽  
The Given

Abstract The quality of welded joints depends on many factors. The relevant standards stipulate technical conditions of welds quality assessment, which provides the basis for stating whether the given joint is compatible with the requirements or whether it is defective. In practice, making welded joints that are totally devoid of defects is extremely difficult. To conduct the control of inner structure of the given joint a non-destructive method with the application of industrial CT scanner might be applied. This modern diagnosing method combines the x-ray examination with advanced computer technology. The basic advantage of computer-assisted tomography consists in examining objects in three dimensions and the possibility to carry out three-dimensional reconstructions. The aim of this article is to discuss the use of this method to evaluate the quality of welded joints made of aluminium alloys. Capabilities of computer-assisted tomography were depicted by the case of weld probes constructed with TIG (ang. Tungsten Inert Gas) welding by different process variables. One has made the analysis of the quality of probes showing the smallest and the biggest internal and external welding defects.

scholarly journals GPR56/ADGRG1 is a platelet collagen-responsive GPCR and hemostatic sensor of shear force

2020 ◽  
Vol 117 (45) ◽  
pp. 28275-28286 ◽  
Author(s):  
Jennifer Yeung ◽  
Reheman Adili ◽  
Emily N. Stringham ◽  
Rong Luo ◽  
Alexander Vizurraga ◽  
...  
Keyword(s):  
Blood Flow ◽  
G Protein ◽  
Shear Force ◽  
Platelet Adhesion ◽  
Shape Change ◽  
Blood Perfusion ◽  
Perfusion Studies ◽  
Platelet Receptor ◽  
Plug Formation ◽  
Platelet Shape

Circulating platelets roll along exposed collagen at vessel injury sites and respond with filipodia protrusion, shape change, and surface area expansion to facilitate platelet adhesion and plug formation. Various glycoproteins were considered to be both collagen responders and mediators of platelet adhesion, yet the signaling kinetics emanating from these receptors do not fully account for the rapid platelet cytoskeletal changes that occur in blood flow. We found the free N-terminal fragment of the adhesion G protein-coupled receptor (GPCR) GPR56 in human plasma and report that GPR56 is the platelet receptor that transduces signals from collagen and blood flow-induced shear force to activate G protein 13 signaling for platelet shape change.Gpr56−/−mice have prolonged bleeding, defective platelet plug formation, and delayed thrombotic occlusion. Human and mouse blood perfusion studies demonstrated GPR56 and shear-force dependence of platelet adhesion to immobilized collagen. Our work places GPR56 as an initial collagen responder and shear-force transducer that is essential for platelet shape change during hemostasis.

scholarly journals Three-dimensional multi-scale model of deformable platelets adhesion to vessel wall in blood flow

2014 ◽  
Vol 372 (2021) ◽  
pp. 20130380 ◽  
Author(s):  
Ziheng Wu ◽  
Zhiliang Xu ◽  
Oleg Kim ◽  
Mark Alber
Keyword(s):  
Blood Flow ◽  
Blood Vessel ◽  
Vessel Wall ◽  
Platelet Adhesion ◽  
Three Dimensional ◽  
Clot Formation ◽  
Scale Model ◽  
Injury Site ◽  
Platelet Receptors ◽  
Multi Scale

When a blood vessel ruptures or gets inflamed, the human body responds by rapidly forming a clot to restrict the loss of blood. Platelets aggregation at the injury site of the blood vessel occurring via platelet–platelet adhesion, tethering and rolling on the injured endothelium is a critical initial step in blood clot formation. A novel three-dimensional multi-scale model is introduced and used in this paper to simulate receptor-mediated adhesion of deformable platelets at the site of vascular injury under different shear rates of blood flow. The novelty of the model is based on a new approach of coupling submodels at three biological scales crucial for the early clot formation: novel hybrid cell membrane submodel to represent physiological elastic properties of a platelet, stochastic receptor–ligand binding submodel to describe cell adhesion kinetics and lattice Boltzmann submodel for simulating blood flow. The model implementation on the GPU cluster significantly improved simulation performance. Predictive model simulations revealed that platelet deformation, interactions between platelets in the vicinity of the vessel wall as well as the number of functional GPIb α platelet receptors played significant roles in platelet adhesion to the injury site. Variation of the number of functional GPIb α platelet receptors as well as changes of platelet stiffness can represent effects of specific drugs reducing or enhancing platelet activity. Therefore, predictive simulations can improve the search for new drug targets and help to make treatment of thrombosis patient-specific.

Blood Platelet Surface Interactions on Fibrinogen Under Flow as Viewed With Fluorescent Video-Microscopy

1986 ◽  
Vol 108 (1) ◽  
pp. 49-53 ◽  
Author(s):  
I. A. Feuerstein ◽  
J. Kush
Keyword(s):  
Platelet Adhesion ◽  
Blood Platelets ◽  
Blood Platelet ◽  
Video Microscopy ◽  
Platelet Surface ◽  
Shear Rates ◽  
Luminal Area ◽  
Coated Surface ◽  
First Contact ◽  
Adhesion Process

The interaction of fluorescently labeled blood platelets with fibrinogen-coated glass was studied in Poiseuille flow at 3 wall shear rates, 40, 80 and 944 s−1. Observations were made via video-microscopy at a distance of 0.5 cm from a tube’s entrance over a 1370 μm2 portion of luminal area. The rates of arrival and detachment, and the net rate of adhesion of cells increased nonlinearly with flow rate. The fraction of arriving cells, first contacts, which adhered without subsequent movement and the fraction of arriving cells which adhered, moved to new positions and then remained adherent, were maximal at 80 s−1. For platelets which adhere and then move to a number of new positions, the likelihood of permanent adhesion is greater than 85 percent. The adhesion process is one in which 40–60 percent of cells permanently adhere on first contact with an additional 30 percent adhering after several moves along the surface. Cells contacting where a platelet was previously adherent had a greater chance of adhering than they would on an unaltered fibrinogen surface. The efficiency of platelet adhesion is greater for second contacts than for first contacts on unaltered fibrinogen coated surface.

RHEOLOGY AND PLATELET-SURFACE ADHESION

1987 ◽  
Author(s):  
S K Sakariassen ◽  
E Fressinaud ◽  
D Meyer ◽  
J J Sixma ◽  
R H Baumgartner
Keyword(s):  
Monoclonal Antibodies ◽  
Shear Rate ◽  
Vascular Injury ◽  
Platelet Adhesion ◽  
Surface Adhesion ◽  
Initial Attachment ◽  
Platelet Surface ◽  
Shear Rates ◽  
Coated Surfaces ◽  
Platelet Spreading

The process of platelet adhesion to sites of vascular injury is pivotal for the arrest of bleeding. The same process may, on the other hand, lead to formation of mural thrombi and may play a role in atherogenesis through the release of platelet-derived growth factor. The events of platelet-surface adhesion may be divided into initial attachment and the subsequent spreading on the surface. These interactions are mediated by a variety of factors, including glycoproteins (GP) in the platelet membrane, von Willebrand factor (vWF) in plasma, and the composition of the surface.However, in most instances their effects on adhesion are dependent on the shear rate.We have investigated the importance of some of these factors in flowing blood at shear rates ranging from those present in large arteries (≃ 200 sec-1) to those present in the microcirculation (≃2600 sec-1). We used annular- and parallel-plate-perfusion chambers with de-endothelial-ized human arteries and collagen-coated surfaces, respectively. A highly reactive surface, such as formed by collagen fibrils, triggers rapid platelet adhesion and thrombus growth on the upstream portion of the surface. This rapid consumption of platelets depletes the boundary layer of the blood flow of platelets, resulting in fewer platelets to adhere further downstream. This effect is most pronounced at shear rates below 650 sec-1, i.e., at conditions with low radial transport of platelets. This phenomenon, apparently physical in nature, we have termed "axial dependence."Deficiency of GPIb results in impaired initial attachment of platelets to subendothelium, a defect which virtually abolishes initial attachment at shear rates above 500 sec-1. However, inhibition of binding of ADP to its putative 100Kd GP receptor by the adenosine analogue 5'-p-fluoro-sulfonyl-adenosine completely prevents initial attachment of platelets. Conversely, deficiency of GPIIb/IIIa results in partially impaired platelet spreading (20-50%), but only at shear rates above 1000 sec-1; deficiency of GPIa results in no platelet spreading, independent of the shear rate. The importance of GPIb and GPIIb/IIIa in adhesion was further demonstrated by experiments using monoclonal antibodies to either GPIb or GPIIb/IIIa.Addition of these antibodies to blood from healthy subjects duplicates the effects found in the natural deficiency states. Furthermore, we used two monoclonal antibodies to vWF, which specifically inhibit either ristocetin-induced binding of vWF to GPIb or thrombin/ADP-induced binding of vWF to GPIIb/IIIa. Each of these antibodies inhibits ≃ 90% of adhesion at 2600 sec-1 shear rate, while no effect is seen at 650 sec-1. Inhibition of binding of vWF, fibronectin, and fibrinogen to GPIIb/IIIa by a dodecapeptide of the γ-carboxy terminus of fibrinogen inhibits ≃ 30% of adhesion in normal blood at 2600 sec-1 shear rate. No effect is present at 650 sec-1 shear rate.These experiments indicate that (1) ADP and/or its putative receptor and GPIb are involved in the early phase of adhesion, whereas (2) GPIa and GPIIb/IIIa are involved in the spreading reaction. It is also apparent that (3) GPIb and GPIIb/IIIa act as receptors for vWF in the process of bridging the platelet to sites of vascular injury, and that (4) vWF is required for both initial attachment and spreading. (5) The shear rate has an unambiguous role in these complex interactions and in the "axial dependence" phenomenon.

Computational Fluid Dynamics Analysis of the Performance of Three Hemodialysis Catheters

2010 ◽  
Author(s):  
M. Elkhoury ◽  
N. Youssef ◽  
C. Issa
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Blood Stream ◽  
Double Lumen ◽  
Shear Rates ◽  
Computational Fluid Dynamics Analysis

In this study, FLUENT (computational fluid dynamics software) is utilized to compare the performance of three widely used hemodialysis catheters, Niagara double lumen, Flexxicon II double lumen and Hemosplit long-term catheters of BARD Access Systems, in terms of blood flow rate and shorter exposure time. Running the three models at a fixed blood flow rate of 300 ml/min, it is found that Niagara catheter displays the lowest shear rates, yet high enough to induce thrombosis, which occurs as a result of platelet aggregation. High vorticity magnitudes exceeding 50,000s−1 are detected near the venous luminal walls of the Hemosplit catheter rendering the formation of Hemolysis which causes free toxic hemoglobin to circulate in the blood stream. Furthermore, the highest shear rates are found to occur at the arterial inlet, downstream the openings where inflow of blood occurs. It was found that the Niagara catheter, with open side holes, is the most recommended among the three considered catheters.

Computer Assisted Image Reconstruction of Oligomer Structure

1976 ◽  
Vol 34 ◽  
pp. 472-473
Author(s):  
A.M. Jones ◽  
A. Max Fiskin
Keyword(s):  
Three Dimensional ◽  
Depth Of Field ◽  
Computer Assisted ◽  
Projection Data ◽  
Two Dimensional ◽  
Single Particles ◽  
Dimensional Reconstruction ◽  
Computer Assisted Image ◽  
The Fourier Transform ◽  
Space Approach

If the tilt of a specimen can be varied either by the strategy of observing identical particles orientated randomly or by use of a eucentric goniometer stage, three dimensional reconstruction procedures are available (l). If the specimens, such as small protein aggregates, lack periodicity, direct space methods compete favorably in ease of implementation with reconstruction by the Fourier (transform) space approach (2). Regardless of method, reconstruction is possible because useful specimen thicknesses are always much less than the depth of field in an electron microscope. Thus electron images record the amount of stain in columns of the object normal to the recording plates. For single particles, practical considerations dictate that the specimen be tilted precisely about a single axis. In so doing a reconstructed image is achieved serially from two-dimensional sections which in turn are generated by a series of back-to-front lines of projection data.

convergent-beam diffraction from surfaces

1987 ◽  
Vol 45 ◽  
pp. 30-33
Author(s):  
J. A. Eades ◽  
A. E. Smith ◽  
D. F. Lynch
Keyword(s):  
Reciprocal Lattice ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Three Dimensions ◽  
Plane Figure ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Beam Patterns ◽  
Beam Diffraction

It is quite simple (in the transmission electron microscope) to obtain convergent-beam patterns from the surface of a bulk crystal. The beam is focussed onto the surface at near grazing incidence (figure 1) and if the surface is flat the appropriate pattern is obtained in the diffraction plane (figure 2). Such patterns are potentially valuable for the characterization of surfaces just as normal convergent-beam patterns are valuable for the characterization of crystals.There are, however, several important ways in which reflection diffraction from surfaces differs from the more familiar electron diffraction in transmission.GeometryIn reflection diffraction, because of the surface, it is not possible to describe the specimen as periodic in three dimensions, nor is it possible to associate diffraction with a conventional three-dimensional reciprocal lattice.

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