Mechanical Characterization of Fresh Human Carotid Atherosclerotic Plaque

2009 ◽  
Author(s):  
Eoghan Maher ◽  
Arthur Creane ◽  
Sherif Sultan ◽  
Niamh Hynes ◽  
Caitríona Lally ◽  
...  
Keyword(s):  
Atherosclerotic Plaque ◽  
Mechanical Characterization ◽  
External Carotid ◽  
Atherosclerotic Plaques ◽  
Finite Element Models ◽  
Tissue Properties ◽  
Surgical Interventions ◽  
The Relationship ◽  
Human Carotid

Quantifying the properties of atherosclerotic plaques is critical to improving our understanding of the pathogenesis of the disease. Furthermore realistic tissue properties are vital in order to obtain legitimate results from finite element models of surgical interventions used to treat cardiovascular disease. The aim of this study is to determine the mechanical properties of fresh human carotid plaques immediately following removal during endarterectomy. A number of studies have reported atherosclerotic plaque properties previously [1–3], however all of these tested cadaveric tissue. This study will further investigate in-patient and inter-patient variability, the relationship between plaque properties and their clinical classification (calcified, mixed or echolucent) and the location of the sample (common, internal, external carotid).

Review: Mechanical Characterization of Carotid Arteries and Atherosclerotic Plaques

2016 ◽  
Vol 63 (10) ◽  
pp. 1613-1623 ◽  
Author(s):  
Chris L. de Korte ◽  
Stein Fekkes ◽  
Aart J. Nederveen ◽  
Rashindra Manniesing ◽  
Hendrik Rik H. G. Hansen
Keyword(s):  
Carotid Arteries ◽  
Mechanical Characterization ◽  
Atherosclerotic Plaques

Expression and Cellular Localization of CXCR4 and CXCL12 in Human Carotid Atherosclerotic Plaques

2018 ◽  
Vol 118 (01) ◽  
pp. 195-206 ◽  
Author(s):  
Sophie Merckelbach ◽  
Emiel van der Vorst ◽  
Michael Kallmayer ◽  
Christoph Rischpler ◽  
Rainer Burgkart ◽  
...  
Keyword(s):  
Protein Level ◽  
Cellular Localization ◽  
Mrna Level ◽  
Plaque Morphology ◽  
Atherosclerotic Plaques ◽  
Cxcl12 Expression ◽  
Carotid Plaques ◽  
Unstable Plaques ◽  
Human Carotid

Background and Aims The CXCR4/CXCL12 complex has already been associated with progression of atherosclerosis; however, its exact role is yet unknown. The aim of this study was to analyse the expression and cellular localization of CXCL12 and its receptor CXCR4 in human carotid atherosclerotic plaques. Methods Carotid plaques (n = 58; 31 stable, 27 unstable, based on histological characterization of plaque morphology) were obtained during carotid endarterectomy, and 10 healthy vessels were used as a control. Expression of cxcr4, cxcr7, cxcl12, ccl2/ccr2 and csf1/csf1r was analysed at mRNA, and level expression of CXCR4, CXCR7 and CXCL12 was analysed at protein level. Cellular localization was determined using consecutive and double immunohistochemical (IHC) staining and microdissection. Results At mRNA level, cxcr4, cxcr7 and cxcl12 were significantly higher expressed in stable carotid plaques compared with controls (p = 0.011, p < 0.001 and p < 0.001). Cxcl12 mRNA expression was successively augmented toward unstable plaques (p < 0.001). At protein level, CXCR4, CXCR7 and CXCL12 expression was significantly increased in both stable (p = 0.001, p < 0.001 and p = 0.035, respectively) and unstable (p = 0.003, p < 0.001 and p = 0.045, respectively) plaques compared with controls. Using IHC, CXCR4 was particularly localized in macrophages and small neovessels. Microdissection confirmed strongest expression of cxcr4 in macrophages within atherosclerotic plaques. Leukocytes and smooth muscle cells showed cxcr4 expression as well. For cxcl12, only microdissected areas with macrophages were positive. Conclusion Expression of CXCR4 and CXCL12 was significantly increased in both stable and unstable carotid atherosclerotic plaques compared with healthy vessels, both at mRNA and protein level. CXCR4 and CXCL12 were localized particularly in macrophages.

Abstract 511: Mrp8 And Mrp14,Endogenous Activators of Toll-lLke Receptor4, are Associated with Rupture-Prone Human Atherosclerotic Plaques

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Mihaela G Ionita ◽  
Gerard Pasterkamp ◽  
Dominique deKleijn
Keyword(s):  
Atherosclerotic Plaque ◽  
Atherosclerotic Plaques ◽  
Atherosclerotic Lesions ◽  
Inflammatory Status ◽  
Potential Marker ◽  
Plaque Phenotype ◽  
Histological Characteristics ◽  
Unstable Plaques ◽  
Human Carotid

Objectives : Atherosclerosis is a chronic, complex inflammatory process and is the underlying cause of stroke and myocardial infarction due to rupture of the atherosclerotic plaque leading to acute occlusion of the artery in the brain or heart. Macrophages, infiltrating atherosclerotic lesions, abundantly express Mrp8 and Mrp14. Recently Mrp8, Mrp14 and the complex Mrp8/14 have been identified as endogenous ligands of Tlr-4.The role of Tlr-4 in the development and progression of the atherosclerotic plaque is well recognized and it is associated with a rupture-prone plaque phenotype. Expression of Mrps in human plaques and its relation to plaque phenotype is unknown. For this, we investigated the levels of Mrp8, Mrp14 and Mrp8/14 complex in a large number of human atherosclerotic plaques. Methods and results : Mrp8, Mrp14 and Mrp8/14 were quantified by ELISAs in human carotid endarterectomy specimens (186 patients) and plaque phenotype was determined by immunohistochemistry. Mrp levels were higher in the unstable (58 fibro-atheromatous, 64 atheromatous) compared to the stable (64 fibrous) plaques: Mrp8 p = 0.001 ; Mrp14 p = 0.001 ; Mrp8/14 p = 0.01 . Concomitantly, Mrp8, Mrp14 and Mrp8/14 were associated with characteristics of unstable plaques: more macrophages ( p = 0.024; p = 0.002; p = 0.076 ), less smooth muscle cells ( p = 0.041; p = 0.001; p = 0.074 ), larger lipid core ( p = 0.001; p = 0.001; p=0.004 ), less collagen ( p = 0.440; p = 0.011; p = 0.372 ). Furthermore, Mrp plaque levels were positively correlated with the pro-inflammatory cytokines (IL-6 and IL-8) and matrix metalloproteinsases (MMP2, MMP8 and MMP9) plaque levels. EDA, marker of stable plaques, was negatively associated with Mrps plaque levels. Histological analysis revealed that Mrps are expressed by a subgroup of plaque macrophages localized in the plaque cap and shoulder, the most rupture-prone sites of an atherosclerotic plaque. Conclusions: We show that Mrp8, Mrp14 and Mrp8/14 are strongly associated with the histological characteristics and inflammatory status of human rupture-prone plaques and identify Mrps as a potential marker for rupture-prone plaques.

Initial Stress in Biomechanical Models of Atherosclerotic Plaques

2011 ◽  
Author(s):  
L. Speelman ◽  
A. C. Akyildiz ◽  
J. J. Wentzel ◽  
E. H. van Brummelen ◽  
J. Jukema ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Finite Element ◽  
Initial Stress ◽  
Atherosclerotic Plaque ◽  
Initial Stresses ◽  
Atherosclerotic Plaques ◽  
Finite Element Models ◽  
Biomechanical Models ◽  
Fibrous Cap ◽  
Stress Studies

Rupture of the cap of an atherosclerotic plaque is instigated when the stresses in the cap due to the blood pressure exceed the local cap strength. Image based computational finite element models of atherosclerotic plaques are widely used to compute stresses in the fibrous cap. These models are often based on pressurized geometries. The shape of the plaque is determined by the blood pressure at the time of imaging, and thus contains initial stresses (IS) and strains, which are generally ignored in plaque stress studies.

scholarly journals An investigation into the critical role of fibre orientation in the ultimate tensile strength and stiffness of human carotid plaque caps

2020 ◽  
Author(s):  
R.D. Johnston ◽  
R.T. Gaul ◽  
C. Lally
Keyword(s):  
Atherosclerotic Plaque ◽  
Critical Role ◽  
Experimental Studies ◽  
Atherosclerotic Lesion ◽  
Collagen Fibre ◽  
Atherosclerotic Plaques ◽  
Fibrous Plaque ◽  
Carotid Plaques ◽  
Risk Of Rupture ◽  
Human Carotid

AbstractThe development and subsequent rupture of atherosclerotic plaques in human carotid arteries is a major cause of ischemic stroke. Mechanical characterization of atherosclerotic plaques can aid our understanding of this rupture risk. Despite this however, experimental studies on human atherosclerotic carotid plaques, and fibrous plaque caps in particular, are very limited. This study aims to provide further insights into atherosclerotic plaque rupture by mechanically testing human fibrous plaque caps, the region of the atherosclerotic lesion most often attributed the highest risk of rupture. The results obtained highlight the variability in the ultimate tensile stress, strain and stiffness experienced in atherosclerotic plaque caps. By pre-screening all samples using small angle light scattering (SALS) to determine the dominant fibre direction in the tissue, along with supporting histological analysis, this work suggests that the collagen fibre alignment in the circumferential direction plays the most dominant role for determining plaque structural stability. The work presented in this study could provide the basis for new diagnostic approaches to be developed, which non-invasively identify carotid plaques at greatest risk of rupture.Graphical Abstract

Mechanical Characterization of Lapping Plate Materials in Diamond Charging Process

2010 ◽  
Vol 126-128 ◽  
pp. 17-22 ◽  
Author(s):  
Hideaki Tanaka ◽  
Hiromu Chiba ◽  
Takehisa Yoshikawa ◽  
K. Iwatsuka ◽  
Yukio Maeda
Keyword(s):  
Work Hardening ◽  
Mechanical Characterization ◽  
Electronic Components ◽  
Work Hardening Coefficient ◽  
Multiple Materials ◽  
The Relationship ◽  
Composite Interfaces ◽  
Hardening Coefficient ◽  
Fixed Abrasive

In the lapping of magnetic heads and other electronic components composed of multiple materials, differences in the processing characteristics of the composite materials result in “residual steps” forming on the surface at composite interfaces. Residual step heights have been reduced to as little as a few nanometers. We investigated using fine abrasives in fixed abrasive lapping for this purpose, which requires highly secure, high-density embedding of the abrasives on the lapping plate. To this end, we modeled the abrasive embedding process and investigated the relationship between the mechanical properties of the lapping plate and the retention of the abrasive, to determine the direction of further research and development. The results of this investigation revealed a correlation between the work hardening in the plate and the resulting abrasive density and cutting edge height. The investigation also showed that it is possible to suppress the reduction in lapping rate that occurs during use by increasing the work hardening coefficient of the plate.

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