scholarly journals Multicomponent Mechanical Characterization of Atherosclerotic Human Coronary Arteries: An Experimental and Computational Hybrid Approach

2021 ◽  
Vol 12 ◽  
Author(s):  
Su Guvenir Torun ◽  
Hakki M. Torun ◽  
Hendrik H. G. Hansen ◽  
Giulia Gandini ◽  
Irene Berselli ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Coronary Arteries ◽  
Cross Sections ◽  
Plaque Rupture ◽  
Ex Vivo ◽  
Hybrid Approach ◽  
Material Model ◽  
Bayesian Optimization ◽  
High Frequency Ultrasound ◽  
Atherosclerotic Plaque Rupture

Atherosclerotic plaque rupture in coronary arteries, an important trigger of myocardial infarction, is shown to correlate with high levels of pressure-induced mechanical stresses in plaques. Finite element (FE) analyses are commonly used for plaque stress assessment. However, the required information of heterogenous material properties of atherosclerotic coronaries remains to be scarce. In this work, we characterized the component-wise mechanical properties of atherosclerotic human coronary arteries. To achieve this, we performed ex vivo inflation tests on post-mortem human coronary arteries and developed an inverse FE modeling (iFEM) pipeline, which combined high-frequency ultrasound deformation measurements, a high-field magnetic resonance-based artery composition characterization, and a machine learning-based Bayesian optimization (BO) with uniqueness assessment. By using the developed pipeline, 10 cross-sections from five atherosclerotic human coronary arteries were analyzed, and the Yeoh material model constants of the fibrous intima and arterial wall components were determined. This work outlines the developed pipeline and provides the knowledge of non-linear, multicomponent mechanical properties of atherosclerotic human coronary arteries.

scholarly journals Tissue-engineered Collagenous Fibrous Cap Models to Systematically Elucidate Atherosclerotic Plaque Rupture.

2021 ◽  
Author(s):  
T.B. Wissing ◽  
K. Van der Heiden ◽  
S.M. Serra ◽  
A.I.P.M. Smits ◽  
C.V.C. Bouten ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Plaque Rupture ◽  
Tissue Mechanics ◽  
Reciprocal Relationships ◽  
Fibrous Cap ◽  
Soft Inclusion ◽  
Atherosclerotic Plaque Rupture ◽  
Collagenous Tissues ◽  
Heterogeneous Tissues ◽  
Culture Protocol

Abstract A significant amount of vascular thrombotic events is associated with rupture of the fibrous cap that overlie atherosclerotic plaques. Cap rupture is however difficult to predict due to the heterogenous composition of the plaque, unknown material properties, and the stochastic nature of the event. Here, we aim to create tissue engineered human fibrous cap models with a variable but controllable collagen composition, suitable for mechanical testing, to scrutinize the reciprocal relationships between composition and mechanical properties. Myofibroblasts were cultured in 1 x 1.5 cm-sized fibrin-based constrained gels for 21 days according to established (dynamic) culture protocols (i.e. static, intermittent or continuous loading) to vary collagen composition (e.g. amount, type and organization). At day 7, a soft 2 mm ∅ fibrin inclusion was introduced in the centre of each tissue to mimic the soft lipid core, simulating the heterogeneity of a plaque. Results demonstrate reproducible collagenous tissues, that mimic the bulk mechanical properties of human caps and vary in collagen composition due to the presence of an successfully integrated soft inclusion and the culture protocol applied. The models can be deployed to assess tissue mechanics, evolution and failure of fibrous caps or complex heterogeneous tissues in general.

Sudden Death in Coronary Artery Disease are Associated With High 3D Critical Plaque Wall Stress: A 3D Multi-Patient FSI Study Based on Ex Vivo MRI of Coronary Plaques

2013 ◽  
Author(s):  
Xueying Huang ◽  
Chun Yang ◽  
Jie Zheng ◽  
Richard Bach ◽  
David Muccigrosso ◽  
...  
Keyword(s):  
Computational Models ◽  
Plaque Rupture ◽  
Ex Vivo ◽  
Carotid Artery Disease ◽  
Wall Stress ◽  
Carotid Plaques ◽  
Group 2 ◽  
Artery Disease ◽  
Atherosclerotic Plaque Rupture

Atherosclerotic plaque rupture is the primary cause of cardiovascular clinical events such as heart attack and stroke. It is commonly believed that plaque rupture may be linked to critical mechanical conditions. Image-based computational models of vulnerable plaques have been introduced seeking critical mechanical indicators which may be used to identify potential sites of rupture [1–5]. A recent study by Tang et al. [4] using in vivo MRI-based 3D fluid-structure interaction (FSI) models for human carotid plaques with and without rupture reported that higher critical plaque wall stress (CPWS) values were associated with plaques with rupture, compared to those without rupture. However, existing computational plaque models are mostly for carotid plaques based on MRI data. Comparable similar studies for coronary plaques are lacking in the current literature. In this study, 3D computational multi-component models with FSI were constructed to identified 3D critical plaque wall stress, critical flow shear stress (CFSS) based on ex vivo MRI data of coronary plaques acquired from 10 patients. The patients were split into 2 groups: patients died in carotid artery disease (CAD, Group 1, 6 patients) and non CAD (Group 2, 4 patients). The possible link between CPWS and death in CAD was investigated by comparing the CPWS values from the two groups.

scholarly journals Neutrophil extracellular traps induce MCP-1 release from endothelial cells at the plaque rupture site in acute myocardial infarction

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
A Ondracek ◽  
T.M Hofbauer ◽  
A Mangold ◽  
T Scherz ◽  
V Seidl ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Endothelial Cells ◽  
Plaque Rupture ◽  
Ex Vivo ◽  
Coronary Intervention ◽  
Neutrophil Extracellular Traps ◽  
Funding Source ◽  
Extracellular Traps

Abstract Introduction Leukocyte-mediated inflammation is crucial in acute myocardial infarction (AMI). We recently observed that neutrophil extracellular traps (NETs) are increased at the culprit site, promoting activation and differentiation of fibrocytes, cells with mesenchymal and leukocytic properties. Fibrocyte migration is mediated by monocyte chemoattractant protein (MCP)-1 and C-C chemokine receptor type 2 (CCR2). We investigated the interplay between NETs, fibrocyte function, and MCP-1 in AMI. Methods Culprit site and femoral blood of AMI patients was drawn during percutaneous coronary intervention. We characterized CCR2 expression of fibrocytes by flow cytometry. MCP-1 and the NET marker citrullinated histone H3 (citH3) were measured by ELISA. Fibrocytes were treated in vitro with MCP-1. Human coronary arterial endothelial cells (hCAECs) were stimulated with isolated NETs, and MCP-1 was measured by ELISA and qPCR. The influence of MCP-1 on NET formation in vitro was assessed using isolated neutrophils. Results We have included 50 consecutive AMI patients into the study. NETs and concentrations of MCP-1 were increased at the CLS. NET stimulation of hCAECs induced MCP-1 on mRNA and protein level. Increasing MCP-1 gradient was associated with fibrocyte accumulation at the site of occlusion. In the presence of higher MCP-1 these fibrocytes expressed proportionally less CCR2 than peripheral fibrocytes. In vitro, MCP-1 dose-dependently decreased fibrocyte CCR2 and reduced ex vivo NET release of healthy donor neutrophils. Conclusions NETs induce endothelial MCP-1 release, presumably promoting a chemotactic gradient for leukocyte and fibrocyte migration. MCP-1 mediated inhibition of NET formation could point to a negative feedback loop. These data will shed light on vascular healing. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Austrian Science Fund

scholarly journals New Hybrid Approach for Developing Automated Machine Learning Workflows: A Real Case Application in Evaluation of Marcellus Shale Gas Production

Fuels ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 286-303
Author(s):  
Vuong Van Pham ◽  
Ebrahim Fathi ◽  
Fatemeh Belyadi
Keyword(s):  
Artificial Intelligence ◽  
Machine Learning ◽  
Shale Gas ◽  
Field Data ◽  
Marcellus Shale ◽  
Hybrid Approach ◽  
Gas Production ◽  
Bayesian Optimization ◽  
Real Field ◽  
Engineering Problems

The success of machine learning (ML) techniques implemented in different industries heavily rely on operator expertise and domain knowledge, which is used in manually choosing an algorithm and setting up the specific algorithm parameters for a problem. Due to the manual nature of model selection and parameter tuning, it is impossible to quantify or evaluate the quality of this manual process, which in turn limits the ability to perform comparison studies between different algorithms. In this study, we propose a new hybrid approach for developing machine learning workflows to help automated algorithm selection and hyperparameter optimization. The proposed approach provides a robust, reproducible, and unbiased workflow that can be quantified and validated using different scoring metrics. We have used the most common workflows implemented in the application of artificial intelligence (AI) and ML in engineering problems including grid/random search, Bayesian search and optimization, genetic programming, and compared that with our new hybrid approach that includes the integration of Tree-based Pipeline Optimization Tool (TPOT) and Bayesian optimization. The performance of each workflow is quantified using different scoring metrics such as Pearson correlation (i.e., R2 correlation) and Mean Square Error (i.e., MSE). For this purpose, actual field data obtained from 1567 gas wells in Marcellus Shale, with 121 features from reservoir, drilling, completion, stimulation, and operation is tested using different proposed workflows. A proposed new hybrid workflow is then used to evaluate the type well used for evaluation of Marcellus shale gas production. In conclusion, our automated hybrid approach showed significant improvement in comparison to other proposed workflows using both scoring matrices. The new hybrid approach provides a practical tool that supports the automated model and hyperparameter selection, which is tested using real field data that can be implemented in solving different engineering problems using artificial intelligence and machine learning. The new hybrid model is tested in a real field and compared with conventional type wells developed by field engineers. It is found that the type well of the field is very close to P50 predictions of the field, which shows great success in the completion design of the field performed by field engineers. It also shows that the field average production could have been improved by 8% if shorter cluster spacing and higher proppant loading per cluster were used during the frac jobs.

Ferrite-encapsulated nanoparticles with stable photothermal performance for multimodal imaging-guided atherosclerotic plaque neovascularization therapy

2021 ◽  
Author(s):  
Zhuowen Yang ◽  
Jianting Yao ◽  
Jianxin Wang ◽  
Cong Zhang ◽  
Yang Cao ◽  
...  
Keyword(s):  
Atherosclerotic Plaque ◽  
Multimodal Imaging ◽  
Plaque Rupture ◽  
Pathological Angiogenesis ◽  
Atherosclerotic Plaque Rupture ◽  
Encapsulated Nanoparticles

Pathological angiogenesis is a critical contributor to atherosclerotic plaque rupture. However, there are few effective theranostic strategies to stabilize plaques by suppressing neovascularization. A polymeric nanosystem using 3 nm manganese...

scholarly journals Myorelaxant Effect of the Dysphania ambrosioides Essential Oil on Sus scrofa domesticus Coronary Artery and Its Toxicity in the Drosophila melanogaster Model

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2041
Author(s):  
Luiz Jardelino de Lacerda Neto ◽  
Andreza Guedes Barbosa Ramos ◽  
Renata Evaristo Rodrigues da Silva ◽  
Luís Pereira-de-Morais ◽  
Fernanda Maria Silva ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Smooth Muscle ◽  
Coronary Artery ◽  
Essential Oil ◽  
Coronary Arteries ◽  
Sus Scrofa ◽  
Ex Vivo ◽  
Alternative Methods ◽  
Major Constituent ◽  
Sus Scrofa Domesticus

Purpose: Alternative methods for the use of animals in research have gained increasing importance, due to assessments evaluating the real need for their use and the development of legislation that regulates the subject. The principle of the 3R’s (replacement, reduction and refinement) has been an important reference, such that in vitro, ex vivo and cord replacement methods have achieved a prominent place in research. Methods: Therefore, due to successful results from studies developed with these methods, the present study aimed to evaluate the myorelaxant effect of the Dysphania ambrosioides essential oil (EODa) using a Sus scrofa domesticus coronary artery model, and the toxicity of both the Dysphania ambrosioides essential oil and its major constituent, α-terpinene, against Drosophila melanogaster in toxicity and negative geotaxis assays. Results: The EODa relaxed the smooth muscle of swine coronary arteries precontracted with K+ and 5-HT in assays using Sus scrofa domesticus coronary arteries. The toxicity results presented LC50 values of 1.546 mg/mL and 2.282 mg/mL for the EODa and α-terpinene, respectively, thus showing the EODa and α-terpinene presented toxicity to these dipterans, with the EODa being more toxic. Conclusions: Moreover, the results reveal the possibility of using the EODa in vascular disease studies since it promoted the relaxation of the Sus scrofa domesticus coronary smooth muscle.

scholarly journals Synthetic Aperture Imaging Using High-Frequency Convex Array for Ophthalmic Ultrasound Applications

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2275
Author(s):  
Hae Gyun Lim ◽  
Hyung Ham Kim ◽  
Changhan Yoon
Keyword(s):  
Image Quality ◽  
Penetration Depth ◽  
Spatial Resolution ◽  
High Frequency ◽  
Imaging System ◽  
Ex Vivo ◽  
Synthetic Aperture ◽  
Single Element ◽  
High Frequency Ultrasound ◽  
Synthetic Aperture Imaging

High-frequency ultrasound (HFUS) imaging has emerged as an essential tool for pre-clinical studies and clinical applications such as ophthalmic and dermatologic imaging. HFUS imaging systems based on array transducers capable of dynamic receive focusing have considerably improved the image quality in terms of spatial resolution and signal-to-noise ratio (SNR) compared to those by the single-element transducer-based one. However, the array system still suffers from low spatial resolution and SNR in out-of-focus regions, resulting in a blurred image and a limited penetration depth. In this paper, we present synthetic aperture imaging with a virtual source (SA-VS) for an ophthalmic application using a high-frequency convex array transducer. The performances of the SA-VS were evaluated with phantom and ex vivo experiments in comparison with the conventional dynamic receive focusing method. Pre-beamformed radio-frequency (RF) data from phantoms and excised bovine eye were acquired using a custom-built 64-channel imaging system. In the phantom experiments, the SA-VS method showed improved lateral resolution (>10%) and sidelobe level (>4.4 dB) compared to those by the conventional method. The SNR was also improved, resulting in an increased penetration depth: 16 mm and 23 mm for the conventional and SA-VS methods, respectively. Ex vivo images with the SA-VS showed improved image quality at the entire depth and visualized structures that were obscured by noise in conventional imaging.

Comparison of the Cross Sectional Area, the Loss in Volume and the Mechanical Properties of LAE442 and MgCa0.8 as Resorbable Magnesium Alloy Implants after 12 Months Implantation Duration

2010 ◽  
Vol 638-642 ◽  
pp. 675-680 ◽  
Author(s):  
Martina Thomann ◽  
Nina von der Höh ◽  
Dirk Bormann ◽  
Dina Rittershaus ◽  
C. Krause ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cross Sections ◽  
Degradation Process ◽  
Cross Sectional Area ◽  
Bending Test ◽  
Sectional Area ◽  
Cross Sectional ◽  
Initial Strength ◽  
Three Point Bending ◽  
The Cross

Current research focuses on magnesium based alloys in the course of searching a resorbable osteosynthetic material which provides sufficient mechanical properties besides a good biocompatibility. Previous studies reported on a favorable biocompatibility of the alloys LAE442 and MgCa0.8. The present study compared the degradation process of cylindrical LAE442 and MgCa0.8 implants after 12 months implantation duration. Therefore, 10 extruded implants (2.5 x 25 mm, cross sectional area 4.9 mm²) of both alloys were implanted into the medullary cavity of both tibiae of rabbits for 12 months. After euthanization, the right bone-implant-compound was scanned in a µ-computed tomograph (µCT80, ScancoMedical) and nine uniformly distributed cross-sections of each implant were used to determine the residual implants´ cross sectional area (Software AxioVisionRelease 4.5, Zeiss). Left implants were taken out of the bone carefully. After weighing, a three-point bending test was carried out. LAE442 implants degraded obviously slower and more homogeneously than MgCa0.8. The mean residual cross sectional area of LAE442 implants was 4.7 ± 0.07 mm². MgCa0.8 showed an area of only 2.18 ± 1.03 mm². In contrast, the loss in volume of LAE442 pins was more obvious. They lost 64 % of their initial weight. The volume of MgCa0.8 reduced clearly to 54.4 % which corresponds to the cross sectional area results. Three point bending tests revealed that LAE442 showed a loss in strength of 71.2 % while MgCa0.8 lost 85.6 % of its initial strength. All results indicated that LAE442 implants degraded slowly, probably due to the formation of a very obvious degradation layer. Degradation of MgCa0.8 implants was far advanced.

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