scholarly journals On the Impact of Vessel Wall Stiffness on Quantitative Flow Dynamics in a Synthetic Model of the Thoracic Aorta

2021 ◽  
Author(s):  
Judith Zimmermann ◽  
Michael Loecher ◽  
Fikunwa Kolawole ◽  
Kathrin Bäumler ◽  
Kyle Gifford ◽  
...  
Keyword(s):  
Thoracic Aorta ◽  
Temporal Resolution ◽  
Aortic Wall ◽  
Predictive Marker ◽  
Flow Dynamics ◽  
4D Flow ◽  
Cross Sectional ◽  
Wall Stiffness ◽  
The Impact

Abstract Aortic wall stiffening is a predictive marker for morbidity in hypertensive patients. Arterial pulse wave velocity (PWV) correlates with the level of stiffness and can be derived using non-invasive 4D-flow magnetic resonance imaging (MRI). The objectives of this study were twofold: to develop subject-specific thoracic aorta models embedded into an MRI-compatible flow circuit operating under controlled physiological conditions; and to evaluate how a range of aortic wall stiffness impacts 4D-flow-based quantification of hemodynamics, particularly PWV. Three aorta models were 3D-printed using a novel photopolymer material at two compliant and one nearly rigid stiffnesses and characterized via tensile testing. Luminal pressure and 4D-flow MRI data were acquired for each model and cross-sectional net flow, peak velocities, and PWV were measured. In addition, the confounding effect of temporal resolution on all metrics was evaluated. Stiffer models resulted in increased systolic pressures (112, 116, and 133 mmHg), variations in velocity patterns, and increased peak velocities, peak flow rate, and PWV (5.8 to 7.3 m/s). Lower temporal resolution (20 ms down to 62.5 ms per image frame) impacted estimates of peak velocity and PWV (7.31 down to 4.77 m/s). Using compliant aorta models is essential to produce realistic flow dynamics and conditions that recapitulated in vivo hemodynamics.

scholarly journals On the impact of vessel wall stiffness on quantitative flow dynamics in a synthetic model of the thoracic aorta

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Judith Zimmermann ◽  
Michael Loecher ◽  
Fikunwa O. Kolawole ◽  
Kathrin Bäumler ◽  
Kyle Gifford ◽  
...  
Keyword(s):  
Thoracic Aorta ◽  
Temporal Resolution ◽  
Aortic Wall ◽  
Predictive Marker ◽  
Flow Dynamics ◽  
4D Flow ◽  
Cross Sectional ◽  
Wall Stiffness ◽  
The Impact

AbstractAortic wall stiffening is a predictive marker for morbidity in hypertensive patients. Arterial pulse wave velocity (PWV) correlates with the level of stiffness and can be derived using non-invasive 4D-flow magnetic resonance imaging (MRI). The objectives of this study were twofold: to develop subject-specific thoracic aorta models embedded into an MRI-compatible flow circuit operating under controlled physiological conditions; and to evaluate how a range of aortic wall stiffness impacts 4D-flow-based quantification of hemodynamics, particularly PWV. Three aorta models were 3D-printed using a novel photopolymer material at two compliant and one nearly rigid stiffnesses and characterized via tensile testing. Luminal pressure and 4D-flow MRI data were acquired for each model and cross-sectional net flow, peak velocities, and PWV were measured. In addition, the confounding effect of temporal resolution on all metrics was evaluated. Stiffer models resulted in increased systolic pressures (112, 116, and 133 mmHg), variations in velocity patterns, and increased peak velocities, peak flow rate, and PWV (5.8–7.3 m/s). Lower temporal resolution (20 ms down to 62.5 ms per image frame) impacted estimates of peak velocity and PWV (7.31 down to 4.77 m/s). Using compliant aorta models is essential to produce realistic flow dynamics and conditions that recapitulated in vivo hemodynamics.

scholarly journals Wall shear stress in the thoracic aorta at rest and with dobutamine stress after arterial switch operation

2020 ◽  
Author(s):  
Roel L F van der Palen ◽  
Joe F Juffermans ◽  
Lucia J M Kroft ◽  
Mark G Hazekamp ◽  
Hildo J Lamb ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Thoracic Aorta ◽  
Aortic Wall ◽  
Arterial Switch Operation ◽  
Dobutamine Stress ◽  
Lv Function ◽  
Resonance Imaging ◽  
4D Flow ◽  
Switch Operation ◽  
Lv Ejection Fraction

Abstract OBJECTIVES Progressive root dilatation is an important complication in patients with transposition of the great arteries (TGA) after arterial switch operation (ASO) that may be caused by altered flow dynamics. Aortic wall shear stress (WSS) distribution at rest and under dobutamine stress (DS) conditions using 4D flow magnetic resonance imaging were investigated in relation to thoracic aorta geometry. METHODS 4D flow magnetic resonance imaging was performed in 16 adolescent TGA patients after ASO (rest and DS condition) and in 10 healthy controls (rest). The primary outcome measure was the WSS distribution along the aortic segments and the WSS change with DS in TGA patients. Based on the results, we secondary zoomed in on factors [aortic geometry and left ventricular (LV) function parameters] that might relate to these WSS distribution differences. Aortic diameters, arch angle, LV function parameters (stroke volume, LV ejection fraction, cardiac output) and peak systolic aortic WSS were obtained. RESULTS TGA patients had significantly larger neoaortic root and smaller mid-ascending aorta (AAo) dimensions and aortic arch angle. At rest, patients had significantly higher WSS in the entire thoracic aorta, except for the dilated root. High WSS levels beyond the proximal AAo were associated with the diameter decrease from the root to the mid-AAo (correlation coefficient r = 0.54–0.59, P = 0.022–0.031), not associated with the aortic arch angle. During DS, WSS increased in all aortic segments (P < 0.001), most pronounced in the AAo segments. The increase in LV ejection fraction, stroke volume and cardiac output as a result of DS showed a moderate linear relationship with the WSS increase in the distal AAo (correlation coefficient r = 0.54–0.57, P = 0.002–0.038). CONCLUSIONS Increased aortic WSS was observed in TGA patients after ASO, related to the ASO-specific geometry, which increased with DS. Stress-enhanced elevated WSS may play a role in neoaortic root dilatation and anterior aortic wall thinning of the distal AAo.

scholarly journals Imaging-Based Biomarkers: Characterization of Post-Kawasaki Vasculitis in Infants and Hypertension Phenotype in Rat Model

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Roch Listz Maurice ◽  
Nagib Dahdah ◽  
Johanne Tremblay
Keyword(s):  
Mechanical Properties ◽  
Arterial Wall ◽  
Turning Point ◽  
Aortic Wall ◽  
Brown Norway ◽  
Carotid Stiffness ◽  
Old Rats ◽  
The Impact

Background. Investigating the mechanical properties of the arteries is essential in cardiovascular diseases. Recent imaging modalities allow mapping mechanical properties within the arterial wall.Aims. We report the potential ofimaging-based biomarker(ImBioMark) to investigate the effect of aging on the rat. We also present preliminary data with ImBioMark characterizing vascular sequelae of Kawasaki disease (KD) in young humans.Methods. We investigatedin vivothe effect of aging on male Brown Norway (BN) rats' (n=5) carotid stiffness. In a second experiment, the impact of KD on the ascending aorta (AA) was examined in KD children (n=2) aged 13 ± 1.41 years old compared to KD-free children (n=5) aged 13.13 ± 0.18 years old.Results. The stiffness of BN's carotid artery was three times stiffer in the old rats, with a turning point at 40 weeks old (P=0.001). KD had a very significant impact on the AA stiffness with strain estimates of 2.39 ± 0.51% versus 4.24 ± 0.65% in controls (P<0.001).Conclusion. ImBioMark phenotypes hypertension in rat models noninvasivelyin vivowithout resorting to euthanasia. Quantifying aortic wall remodeling is also feasible in humans. Future investigations target human cardiovascular disease.

scholarly journals Borna Disease Virus Infection, a Human Mental-Health Risk

2003 ◽  
Vol 16 (3) ◽  
pp. 534-545 ◽  
Author(s):  
Liv Bode ◽  
Hans Ludwig
Keyword(s):  
Disease Virus ◽  
Enzyme Linked Immunosorbent Assay ◽  
Diagnostic Systems ◽  
Cross Sectional ◽  
Borna Disease Virus ◽  
Pros And Cons ◽  
The Impact ◽  
Borna Disease

SUMMARY This article focuses on human Borna disease virus (BDV) infections, most notably on the development of valid diagnostic systems, which have arisen as a major research issue in the past decade. The significance of a novel modular triple enzyme-linked immunosorbent assay that is capable of specifically measuring anti-BDV antibodies as well as major structural proteins N (p40) and P (p24) in the blood, either as free antigens in the plasma or as antibody-bound circulating immune complexes (CICs), is explained. The impact of CICs and plasma antigen, which indicate periods of antigenemia in the course of BDV infection, along with other infection markers that are still in use is discussed. The review further provides new insight into possible links of BDV to human diseases, summarizing cross-sectional and longitudinal data which correlate acute depression with the presence and amount of antigen and CICs. Moreover, BDV prevalence in healthy people is reevaluated, suggesting that this was previously underestimated. Antiviral efficacy of amantadine, in vivo and in vitro, is outlined as well, with emphasis on wild-type (human and equine) versus laboratory strains. Finally, the pros and cons of the association of BDV with human disease, as detailed in the literature, are critically discussed and related to our data and concepts. This article supports existing correlative evidence for a pathogenic role of BDV infection in particular human mental disorders, in analogy to what has been proven for a variety of animal species.

scholarly journals Masticatory system integration in a commensal canid: interrelationships between bones, muscles and bite force in the red fox

2021 ◽  
Vol 224 (5) ◽  
Author(s):  
Colline Brassard ◽  
Marilaine Merlin ◽  
Elodie Monchâtre-Leroy ◽  
Claude Guintard ◽  
Jacques Barrat ◽  
...  
Keyword(s):  
Red Fox ◽  
Bite Force ◽  
Similar Amount ◽  
Canis Lupus Familiaris ◽  
Cross Sectional ◽  
Domestic Species ◽  
Mandible Shape ◽  
The Impact ◽  
Strong Relationships

ABSTRACT The jaw system in canids is essential for defence and prey acquisition. However, how it varies in wild species in comparison with domestic species remains poorly understood, yet is of interest in terms of understanding the impact of artificial selection. Here, we explored the variability and interrelationships between the upper and lower jaws, muscle architecture and bite force in the red fox (Vulpes vulpes). We performed dissections and used 3D geometric morphometric approaches to quantify jaw shape in 68 foxes. We used a static lever model and bite force estimates were compared with in vivo measurements of 10 silver foxes. Our results show strong relationships exist between cranial and mandible shape, and between cranial or mandible shape on the one hand and muscles or estimated bite force on the other hand, confirming the strong integration of the bony and muscular components of the jaw system. These strong relationships are strongly driven by size. The functional links between shape and estimated bite force are stronger for the mandible, which probably reflects its greater specialisation towards biting. We then compared our results with data previously obtained for dogs (Canis lupus familiaris) to investigate the effect of domestication. Foxes and dogs differ in skull shape and muscle physiological cross-sectional area (PCSA). They show a similar amount of morphological variation in muscle PCSA, but foxes show lower variation in cranial and mandible shape. Interestingly, the patterns of covariation are not stronger in foxes than in dogs, suggesting that domestication did not lead to a disruption of the functional links of the jaw system.

scholarly journals Dorsoventral polarity directs cell responses to migration track geometries

2020 ◽  
Vol 6 (31) ◽  
pp. eaba6505
Author(s):  
Emily O. Wisniewski ◽  
Panagiotis Mistriotis ◽  
Kaustav Bera ◽  
Robert A. Law ◽  
Jitao Zhang ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Myosin Ii ◽  
Cross Sectional ◽  
Dorsoventral Polarity ◽  
Rhoa Activity ◽  
Cell Responses ◽  
Aspect Ratios ◽  
The Impact

How migrating cells differentially adapt and respond to extracellular track geometries remains unknown. Using intravital imaging, we demonstrate that invading cells exhibit dorsoventral (top-to-bottom) polarity in vivo. To investigate the impact of dorsoventral polarity on cell locomotion through different confining geometries, we fabricated microchannels of fixed cross-sectional area, albeit with distinct aspect ratios. Vertical confinement, exerted along the dorsoventral polarity axis, induces myosin II–dependent nuclear stiffening, which results in RhoA hyperactivation at the cell poles and slow bleb-based migration. In lateral confinement, directed perpendicularly to the dorsoventral polarity axis, the absence of perinuclear myosin II fails to increase nuclear stiffness. Hence, cells maintain basal RhoA activity and display faster mesenchymal migration. In summary, by integrating microfabrication, imaging techniques, and intravital microscopy, we demonstrate that dorsoventral polarity, observed in vivo and in vitro, directs cell responses in confinement by spatially tuning RhoA activity, which controls bleb-based versus mesenchymal migration.

scholarly journals Data Assimilation by Stochastic Ensemble Kalman Filtering to Enhance Turbulent Cardiovascular Flow Data From Under-Resolved Observations

2021 ◽  
Vol 8 ◽  
Author(s):  
Dario De Marinis ◽  
Dominik Obrist
Keyword(s):  
Data Assimilation ◽  
Flow Field ◽  
Turbulent Flows ◽  
Temporal Resolution ◽  
Flow Fields ◽  
Observation Data ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri

We propose a data assimilation methodology that can be used to enhance the spatial and temporal resolution of voxel-based data as it may be obtained from biomedical imaging modalities. It can be used to improve the assessment of turbulent blood flow in large vessels by combining observed data with a computational fluid dynamics solver. The methodology is based on a Stochastic Ensemble Kalman Filter (SEnKF) approach and geared toward pulsatile and turbulent flow configurations. We describe the observed flow fields by a mean value and its covariance. These flow fields are combined with forecasts obtained from a direct numerical simulation of the flow field. The method is validated against canonical pulsatile and turbulent flows. Finally, it is applied to a clinically relevant configuration, namely the flow downstream of a bioprosthetic valve in an aorta phantom. It is demonstrated how the 4D flow field obtained from experimental observations can be enhanced by the data assimilation algorithm. Results show that the presented method is promising for future use with in vivo data from 4D Flow Magnetic Resonance Imaging (4D Flow MRI). 4D Flow MRI returns spatially and temporally averaged flow fields that are limited by the spatial and the temporal resolution of the tool. These averaged flow fields and the associated uncertainty might be used as observation data in the context of the proposed methodology.

A technique to assess aortic distensibility and compliance in anesthetized and awake rats

1996 ◽  
Vol 270 (2) ◽  
pp. H780-H786 ◽  
Author(s):  
A. Van Gorp ◽  
D. S. Van Ingen Schenau ◽  
J. Willigers ◽  
A. P. Hoeks ◽  
J. G. De Mey ◽  
...  
Keyword(s):  
Aortic Wall ◽  
Cardiac Cycle ◽  
Aortic Distensibility ◽  
Aortic Diameter ◽  
Cross Sectional ◽  
Anesthetized Rats ◽  
Coefficients Of Variation ◽  
Tracking Device ◽  
Awake Rats

A noninvasive ultrasonic technique, based on tracking arterial wall displacements with a vessel wall-tracking device attached to a conventional B-mode imager, to assess end-diastolic aortic diameter (d) and aortic diameter changes during the cardiac cycle (delta d) in anesthetized and awake rats is presented. From these parameters and invasively measured aortic pulse pressure (delta P), aortic distensibility and compliance, the relative and absolute increases in lumen cross-sectional area for a given increase in delta P, respectively, can be calculated. d, delta d, and delta P could be determined with good intra-session (variations per day) and inter-session (variations between days) coefficients of variation (CV). The CVs for delta d were smaller in awake (4.6-6.0%) than in anesthetized rats (7.9-11.0%), probably due to variations in delta P during anesthesia (CV: 9.0-12.3%). The CVs for d in awake (3.3-6.5%) and anesthetized rats (2.6-5.0%) were comparable. In awake rats the CV for delta d, but not for d, increased after implantation of the aortic catheter. It is concluded that d, delta d, and delta P of the aorta can be reliably measured noninvasively in anesthetized and awake rats, allowing the in vivo assessment of aortic distensibility and compliance. The technique is sensitive enough to detect effects of agents on aortic wall properties.

scholarly journals Laquinimod dampens IL-1β signaling and Th17-polarizing capacity of monocytes in patients with MS

2020 ◽  
Vol 8 (1) ◽  
pp. e908
Author(s):  
Sinah Engel ◽  
Valérie Jolivel ◽  
Stefan H.-P. Kraus ◽  
Morad Zayoud ◽  
Karolina Rosenfeld ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
Intracellular Cytokine Staining ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
Activation Markers ◽  
Messenger Ribonucleic Acid ◽  
The Impact

ObjectiveTo assess the impact of laquinimod treatment on monocytes and to investigate the underlying immunomodulatory mechanisms in MS.MethodsIn this cross-sectional study, we performed in vivo and in vitro analyses of cluster of differentiation (CD14+) monocytes isolated from healthy donors (n = 15), untreated (n = 13), and laquinimod-treated patients with MS (n = 14). Their frequency and the expression of surface activation markers were assessed by flow cytometry and the viability by calcein staining. Cytokine concentrations in the supernatants of lipopolysaccharide (LPS)-stimulated monocytes were determined by flow cytometry. The messenger ribonucleic acid (mRNA) expression level of genes involved in cytokine expression was measured by quantitative PCR. The LPS-mediated nuclear factor kappa-light-chain-enhancer of activated B-cell (NF-κB) activation was determined by the quantification of the phosphorylation level of the p65 subunit. Laquinimod-treated monocytes were cocultured with CD4+ T cells, and the resulting cytokine production was analyzed by flow cytometry after intracellular cytokine staining. The interleukin (IL)-17A concentration of the supernatant was assessed by ELISA.ResultsLaquinimod did not alter the frequency or viability of circulating monocytes, but led to an upregulation of CD86 expression. LPS-stimulated monocytes of laquinimod-treated patients with MS secreted less IL-1β following a downregulation of IL-1β gene expression. Phosphorylation levels of the NF-κB p65 subunit were reduced after laquinimod treatment, indicating a laquinimod-associated inhibition of the NF-κB pathway. T cells primed with laquinimod-treated monocytes differentiated significantly less into IL-17A–producing T helper (Th)-17 cells.ConclusionsOur findings suggest that inhibited NF-κB signaling and downregulation of IL-1β expression in monocytes contributes to the immunomodulatory effects of laquinimod and that the impairment of Th17 polarization might mediate its disease-modifying activity in MS.

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