Global Thrombosis Test: Occlusion by Coagulation or SIPA?

AbstractThe global thrombosis test (GTT) is a point of care device that tests thrombotic and thrombolytic status. The device exposes whole blood flow to a combination of both high and low shear stress past and between ball bearings potentially causing thrombin and fibrin formation. The question arises as to whether thrombosis in the GTT is dominated by coagulation-triggered red clot or high shear-induced white clot. We investigated the nature of the thrombus formed in the GTT, the device efficacy, human factors use, and limitations. The GTT formed clots that were histologically fibrin-rich with trapped red blood cells. The occlusion time (OT) was more consistent with coagulation than high shear white clot and was strongly lengthened by heparin and citrate, two common anticoagulants. The clot was lysed by tissue plasminogen activator (tPA), also consistent with a fibrin-rich red clot. Changing the bead to a collagen-coated surface and eliminating the low shear zone between the beads induced a rapid OT consistent with a platelet-rich thrombus that was relatively resistant to heparin or tPA. The evidence points to the GTT as occluding primarily due to fibrin-rich red clot from coagulation rather than high shear platelet aggregation and occlusion associated with arterial thrombosis.

Download Full-text

High glucose induced NF-κB DNA-binding activity in HAEC is maintained under low shear stress but inhibited under high shear stress: role of nitric oxide

Atherosclerosis ◽

10.1016/j.atherosclerosis.2003.08.023 ◽

2003 ◽

Vol 171 (2) ◽

pp. 225-234 ◽

Cited By ~ 17

Author(s):

S Mohan

Keyword(s):

Nitric Oxide ◽

Shear Stress ◽

High Glucose ◽

Binding Activity ◽

High Shear ◽

High Shear Stress ◽

Dna Binding Activity ◽

Low Shear Stress ◽

Low Shear

Download Full-text

Thrombus Initiation With Subsequent Growth Measured for Physiological Shear and High Pathological Shear

ASME 2011 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2011-53865 ◽

2011 ◽

Author(s):

David L. Bark ◽

Andrea N. Para ◽

David N. Ku

Keyword(s):

Myocardial Infarction ◽

Acute Myocardial Infarction ◽

Heart Attack ◽

Arterial Thrombosis ◽

Atherosclerotic Disease ◽

High Shear ◽

Subsequent Growth ◽

Low Shear ◽

Undisturbed Flow

Arterial thrombosis is often found near an atheroma in atherosclerotic disease, which can lead to acute myocardial infarction, i.e. a heart attack. Thrombus typically grows in regions of exposed subendothelium, which can exist when the plaque cap of the atheroma ruptures or erodes. The subendothelium creates an adherent surface to platelets and other thrombus constituents. Furthermore, an atheroma alters the normal physiological hemodynamics, which has been reported to correspond to local thrombus growth, despite equally adherent surfaces in undisturbed flow regions [1,2]. However, there has been some disagreement about which hemodynamics, specifically shear, may play the most influential role of localizing thrombus. Low shear and high shear have both resulted in thrombus growth [1,2]. Shear in the region of an atheroma can get over 100,000 s−1 [3].

Download Full-text

Low shear stress preferentially enhances IKK activity through selective sources of ROS for persistent activation of NF-κB in endothelial cells

AJP Cell Physiology ◽

10.1152/ajpcell.00535.2005 ◽

2007 ◽

Vol 292 (1) ◽

pp. C362-C371 ◽

Cited By ~ 49

Author(s):

Sumathy Mohan ◽

Koichi Koyoma ◽

Amalraj Thangasamy ◽

Hiroyasu Nakano ◽

Randolph D. Glickman ◽

...

Keyword(s):

Endothelial Cells ◽

Shear Stress ◽

Nadph Oxidase ◽

Significant Proportion ◽

Time Frame ◽

Oxidase Inhibitor ◽

Ros Generation ◽

High Shear ◽

Low Shear Stress ◽

Low Shear

NF-κB signaling pathway has been known to play a major role in the pathological process of atherogenesis. Unlike high shear stress, in which the NF-κB activity is transient, our earlier studies have demonstrated a persistent activation of NF-κB in response to low shear stress in human aortic endothelial cells. These findings partially explained why low shear regions that exist at bifurcations of arteries are prone to atherosclerosis, unlike the relatively atheroprotective high shear regions. In the present study, we further investigated 1) the role of NF-κB signaling kinases (IKKα and β) that may be responsible for the sustained activation of NF-κB in low shear stress and 2) the regulation of these kinases by reactive oxygen species (ROS). Our results demonstrate that not only is a significant proportion of low shear-induced-kinase activity is contributed by IKKβ, but it is also persistently induced for a prolonged time frame. The IKK activity (both α and β) is blocked by apocynin (400 μM), a specific NADPH oxidase inhibitor, and diphenyleneiodonium chloride (DPI; 10 μM), an inhibitor of flavin-containing oxidases like NADPH oxidases. Determination of ROS also demonstrated an increased generation in low shear stress that could be blocked by DPI. These results suggest that the source of ROS generation in endothelial cells in response to low shear stress is NADPH oxidase. The DPI-inhibitable component of ROS is the primary regulator of specific upstream kinases that determine the persistent NF-κB activation selectively in low shear-induced endothelial cells.

Download Full-text

Albumin Uptake Into Endothelial Cells in Separated Flow

10.1115/imece2000-2526 ◽

2000 ◽

Author(s):

Susumu Kudo ◽

Ryuhei Yamaguchi ◽

Masashi Sato ◽

Kotaro Oka ◽

Kazuo Tanishita

Keyword(s):

Endothelial Cells ◽

Shear Stress ◽

Cell Morphology ◽

Stress Gradient ◽

Separated Flow ◽

High Shear ◽

High Shear Stress ◽

Low Shear Stress ◽

Shear Stress Gradient ◽

Low Shear

Abstract The purpose of this study is to reveal the albumin uptake into endothelial cells in the separated flow area. After 24 hr of exposure to flow induced in a back step flow channel, the endothelial cells were incubated in 37°C for 60 minutes in PBS containing tetramethylrhodamine isothiocyanate conjugated albumin (TRITC-albumin). Thereafter, the cell morphology and the albumin uptake were observed by a confocal laser scanning microscope (CLSM). In a low shear stress area (stagnant and reattachment areas), the cells aligned randomly. In a high shear stress area (reversal and fully developed areas), the cells were elongated and aligned to flow direction. In low-shear-stress and high-shear-stress gradient areas (reattachment areas), the amount of albumin uptake into the cells was the largest in all areas. These data indicate that shear stress and shear stress gradient affect the endothelial cell morphology and the albumin uptake into endothelial cells.

Download Full-text

Endothelial Cell Morphometry of Atherosclerotic Lesions and Flow Profiles at Aortic Bifurcations in Cholesterol Fed Rabbits

Journal of Biomechanical Engineering ◽

10.1115/1.2891387 ◽

1992 ◽

Vol 114 (3) ◽

pp. 301-308 ◽

Cited By ~ 28

Author(s):

Mitsuji Okano ◽

Yoji Yoshida

Keyword(s):

Endothelial Cells ◽

Shear Stress ◽

Lipid Deposition ◽

High Shear ◽

High Shear Stress ◽

Atherosclerotic Lesions ◽

Flow Profiles ◽

Flow Divider ◽

Low Shear Stress ◽

Low Shear

Observations on shapes of endothelial cells both in sudanophilic and nonsudanophilic regions at bifurcations of the brachiocephalic (BC) and left subclavian (SA) arteries in hyperlipidemic rabbits were performed under a SEM. The stagnation point of flow and leading edges of flow dividers were nonsudanophilic and covered by round and long fusiform endothelial cells, respectively. The hips of flow dividers of both branchings, proven to be relatively low shear stress regions, by movement of microspheres in steady flow, were sudanophilic and covered by ellipsoidal cells. Similar studies were carried out in normolipidemic rabbits. It might be concluded that lipid deposition in hyperlipidemic rabbits occurs in relatively low shear stress regions, where endothelial cells are functionally activated, rather than in laminar high shear stress regions at the flow divider.

Download Full-text

Low Shear Stress Increases Recombinant Protein Production and High Shear Stress Increases Apoptosis in Human Cells

iScience ◽

10.1016/j.isci.2020.101653 ◽

2020 ◽

Vol 23 (11) ◽

pp. 101653

Author(s):

Caijuan Zhan ◽

Gholamreza Bidkhori ◽

Hubert Schwarz ◽

Magdalena Malm ◽

Aman Mebrahtu ◽

...

Keyword(s):

Shear Stress ◽

Recombinant Protein ◽

Recombinant Protein Production ◽

Protein Production ◽

Human Cells ◽

High Shear ◽

High Shear Stress ◽

Low Shear Stress ◽

Low Shear

Download Full-text

Restoration of endothelial autophagic flux in vascular endothelial cells exposed to low shear stress reduces atherosclerotic lesions

Archives of Cardiovascular Diseases Supplements ◽

10.1016/j.acvdsp.2021.04.078 ◽

2021 ◽

Vol 13 (2) ◽

pp. 177

Author(s):

S. Chatterjee ◽

M. Kheloufi ◽

S. Mazlan ◽

X. Loyer ◽

T. Mckinsey ◽

...

Keyword(s):

Endothelial Cells ◽

Shear Stress ◽

Vascular Endothelial Cells ◽

Autophagic Flux ◽

Vascular Endothelial ◽

Atherosclerotic Lesions ◽

Low Shear Stress ◽

Low Shear

Download Full-text

Direct and rapid measurement of hydrogen peroxide in human blood using a microfluidic device

Scientific Reports ◽

10.1038/s41598-021-82623-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

R. Gaikwad ◽

P. R. Thangaraj ◽

A. K. Sen

Keyword(s):

Hydrogen Peroxide ◽

Microfluidic Device ◽

Human Blood ◽

Blood Cells ◽

Limit Of Detection ◽

Point Of Care ◽

Time Interval ◽

Fluorescence Measurement ◽

Rapid Measurement ◽

Automated Method

AbstractThe levels of hydrogen peroxide ($${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 ) in human blood is of great relevance as it has emerged as an important signalling molecule in a variety of disease states. Fast and reliable measurement of $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 levels in the blood, however, continues to remain a challenge. Herein we report an automated method employing a microfluidic device for direct and rapid measurement of $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 in human blood based on laser-induced fluorescence measurement. Our study delineates the critical factors that affect measurement accuracy—we found blood cells and soluble proteins significantly alter the native $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 levels in the time interval between sample withdrawal and detection. We show that separation of blood cells and subsequent dilution of the plasma with a buffer at a ratio of 1:6 inhibits the above effect, leading to reliable measurements. We demonstrate rapid measurement of $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 in plasma in the concentration range of 0–49 µM, offering a limit of detection of 0.05 µM, a sensitivity of 0.60 µM−1, and detection time of 15 min; the device is amenable to the real-time measurement of $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 in the patient’s blood. Using the linear correlation obtained with known quantities of $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 , the endogenous $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 concentration in the blood of healthy individuals is found to be in the range of 0.8–6 µM. The availability of this device at the point of care will have relevance in understanding the role of $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 in health and disease.

Download Full-text