Reframing the Paradigms of Inner Bodies

Awareness of our environments both external and internal are in continuous flux and highly mediated by technologies we have created. The research project we shall discuss is situated at the pivotal point of reframing our perception and consciousness in the context of the current in silico culture. More to the point, we shall refer to inroads into the bi-modal computer-generated simulations of blood flow patterns, in the pathological situation of a brain aneurysm, leading not only to the understanding of the phenomenon but also to the optimal communication of its complexity. This new approach, removed from both in vivo as well as in vitro, brings together visual and sound artists, computer engineers, designers and cognitive scientists with the essential goal of restructuring and re-configuring our understanding of self. This being said, the need to create ways that allow remodeling and reframing our perceptions through easily interactive tools that are also increasingly autonomous is at the core of the research we shall be presenting. Through novel approaches and complex technological mediation, the accompanying conscious experiences co-evolve and develop in complexity. The aim is for this project to serve as an example and starting point for stimulating debate

Sex Differences in Carotid Plaque and Stenosis

Background and Purpose-Women are relatively protected from cardiovascular events; they are 3 times as likely as men to survive to age 90 years. Although clinical trials show an excess of thrombotic events with estrogen/progestin hormone replacement therapy, much experimental and epidemiological evidence suggests that estrogen may have beneficial effects on endothelial function and atherosclerosis, raising the possibility of sex differences in arterial remodeling. We studied sex differences in carotid plaque and stenosis in relation to survival free of stroke, death, and myocardial infarction. Methods-A total of 1686 patients from an atherosclerosis prevention clinic were followed annually for up to 5 years (mean, 2.5 ± 1.3 years) with baseline and follow-up measurements; there were 45 strokes, 94 myocardial infarctions, and 41 deaths. Results-Carotid stenosis and plaque increased with age. Women had greater stenosis compared with men (P=0.001), whereas men had greater plaque area than did women at all ages (P\u3c0.0001). Stroke, myocardial infarction, and death combined were predicted significantly by plaque area (P=0.004) but not by stenosis (P=0.042). Conclusions-Women have more stenosis but less plaque than men, suggesting that differences in sex hormones may affect remodeling of atherosclerosis. Plaque area was a stronger predictor of outcomes than was stenosis

Geometry of the carotid bifurcation predicts its exposure to disturbed flow

BACKGROUND AND PURPOSE: That certain vessels might be at so-called geometric risk of atherosclerosis rests on assumptions of wide interindividual variations in disturbed flow and of a direct relationship between disturbed flow and lumen geometry. In testing these often-implicit assumptions, the present study aimed to determine whether investigations of local risk factors in atherosclerosis can indeed rely on surrogate geometric markers of disturbed flow. METHODS: Computational fluid dynamics simulations were performed on carotid bifurcation geometries derived from MRI of 25 young adults. Disturbed flow was quantified as the surface area exposed to low and oscillatory shear beyond objectively-defined thresholds. Interindividual variations in disturbed flow were contextualized with respect to effects of uncertainties in imaging and geometric reconstruction. Relationships between disturbed flow and various geometric factors were tested via multiple regression. RESULTS: Relatively wide variations in disturbed flow were observed among the 50 vessels. Multiple regression revealed a significant (P\u3c0.002) relationship between disturbed flow and both proximal area ratio (β≈0.5) and bifurcation tortuosity (β≈-0.4), but not bifurcation angle, planarity, or distal area ratio. These findings were shown to be insensitive to assumptions about the flow conditions and to the choice of disturbed flow indicator and threshold. CONCLUSIONS: Certain geometric features of the young adult carotid bifurcation are robust surrogate markers of its exposure to disturbed flow. It may therefore be reasonable to consider large-scale retrospective or prospective imaging studies of local risk factors for atherosclerosis without the need for time-consuming and expensive flow imaging or CFD studies. © 2008 American Heart Association, Inc

Liver macrophages in murine listeriosis: Cell-mediated immunity is correlated with an influx of macrophages capable o f generating reactive oxygen intermediates

[No abstract available

Murine kupffer cells: Mononuclear phagocytes deficient in the generation of reactive oxygen intermediates

[No abstract available

Progress toward sonifying Napoleon’s march and fluid flow simulations through binaural horizons

Cross-modal data analytics—that can be rendered for experience through vision, hearing, and touch—poses a fundamental challenge to designers. Non-linguistic sonification is a well-researched means for non-visual pattern recognition but higher density datasets pose a challenge. Because human hearing is optimized for detecting locations on a horizontal plane, our approach recruits this optimization by employing an immersive binaural horizontal plane using auditory icons. Two case studies demonstrate our approach: A sonic translation of a map and a sonic translation of a computational fluid dynamics simulation

Variation in the carotid bifurcation geometry of young versus older adults: Implications for geometric risk of atherosclerosis

Background and Purpose - Retrospective analysis of clinical data has demonstrated major variations in carotid bifurcation geometry, in support of the notion that an individual\u27s vascular anatomy or local hemodynamics may influence the development of atherosclerosis. On the other hand, anecdotal evidence suggests that vessel geometry is more homogenous in youth, which would tend to undermine this geometric risk hypothesis. The purpose of our study was to test whether the latter is indeed the case. Methods - Cross-sectional images of the carotid bifurcations of 25 young adults (24±4 years) and a control group of 25 older subjects (63±10 years) were acquired via MRI. Robust and objective techniques were developed to automatically characterize the 3D geometry of the bifurcation and the relative dimensions of the internal, external, and common carotid arteries (ICA, ECA, and CCA, respectively). Results - Young vessels exhibited significantly less interindividual variation in the following geometric parameters: bifurcation angle (48.5±6.3° versus 63.6±15.4°); ICA angle (21.6±6.7° versus 29.2±11.3°); CCA tortuosity (0.010±0.003 versus 0.014±0.011); ICA tortuosity (0.025±0.013 versus 0.086±0.105); ECA/CCA diameter ratio (0.81±0.06 versus 0.75±0.13), ICA/CCA (0.81 ±0.06 versus 0.77±0.12) diameter ratio, and bifurcation area ratio (1.32±0.15 versus 1.19±0.35). Conclusions - The finding of more modest interindividual variations in young adults suggests that, if there is a geometric risk for atherosclerosis, its early detection may prove challenging. Taken together with the major interindividual variations seen in older vessels, it suggests a more complex interrelationship between vascular geometry, local hemodynamics, vascular aging, and atherosclerosis, the elucidation of which now calls for prospective studies. © 2005 American Heart Association, Inc

Automated Parameterization and Patching of Bifurcating Vessels

Recent developments in computational modeling of human arteries have opened the possibility of performing subject-specific analyses on increasingly larger numbers of subjects. This achievement will eventually lead to a better understanding of the role of geometry and hemodynamics in the initiation and development of vascular disease. The availability of data from population or longitudinal studies raises the problem of quantitatively comparing distributions of geometric and hemodynamic quantities among different models. This task is made difficult by the fact that modeled arterial segments typically comprise bifurcations and regions of high curvature. A technique for comparing surface distributions among realistic models of the carotid bifurcation has been recently proposed in [1]. In that work, surface mesh nodes were classified as belonging to semi-automatically defined quadrilateral patches, and nodal quantities of interest averaged over each patch. This avoided node-to-node comparison and the need for registration. However, patch definition required user interaction and was thus subject to operator-variability. In this work we present a fully automated technique for parameterization and patching of the surface of bifurcating vessels. The method is based on robust and objective schemes aimed at preserving the consistency of the parameterization over a wide range of bifurcating geometries, allowing quantitative comparison of surface distributions in presence of high anatomic variability

Spatiotemporal Hemodynamic Complexity in Carotid Arteries: An Integrated Computational Hemodynamics and Complex Networks-Based Approach

Objective: The study of the arterial hemodynamics is essential for a better understanding of the risks associated with the onset/progression of vascular disease. However, conventional quantification and visualization paradigms are not sufficient to fully capture the spatiotemporal evolution of correlated blood flow patterns and their “sphere of influence” in complex vascular geometries. In the attempt to bridge this knowledge gap, an integrated computational hemodynamics and complex networks-based approach is proposed to unveil organization principles of cardiovascular flows. Methods: The approach is applied to ten patient-specific hemodynamic models of carotid bifurcation, a vascular bed characterized by a complex hemodynamics and clinically-relevant disease. Correlation-based networks are built starting from time-histories of two fluid mechanics quantities of physiological significance, respectively (1) the blood velocity vector axial component locally aligned with the main flow direction, and (2) the kinetic helicity density. Results: Unlike conventional hemodynamic analyses, here the spatiotemporal similarity of dynamic intravascular flow structures is encoded in a distance function. In the case of the carotid bifurcation, this study measures for the first time to what extent flow similarity is disrupted by vascular geometric features. Conclusion: It emerges that a larger bifurcation expansion, a hallmark of vascular disease, significantly disrupts the network topological connections between axial flow structures, reducing also their anatomical persistence length. On the contrary, connections in helical flow patterns are overall less geometry-sensitive. Significance: The integrated approach proposed here, by exploiting the connections of hemodynamic patterns undergoing similar dynamical evolution, opens avenues for further comprehension of vascular physiopathology

Wall shear stress topological skeleton independently predicts long-term restenosis after carotid bifurcation endarterectomy

Wall Shear Stress (WSS) topological skeleton, composed by fixed points and the manifolds linking them, reflects the presence of blood flow features associated to adverse vascular response. However, the influence of WSS topological skeleton on vascular pathophysiology is still underexplored. This study aimed to identify direct associations between the WSS topological skeleton and markers of vascular disease from real-world clinical longitudinal data of long-term restenosis after carotid endarterectomy (CEA). Personalized computational hemodynamic simulations were performed on a cohort of 13 carotid models pre-CEA and at 1 month after CEA. At 60 months after CEA, intima-media thickness (IMT) was measured to detect long-term restenosis. The analysis of the WSS topological skeleton was carried out by applying a Eulerian method based on the WSS vector field divergence. To provide objective thresholds for WSS topological skeleton quantitative analysis, a computational hemodynamic dataset of 46 ostensibly healthy carotid bifurcation models was considered. CEA interventions did not completely restore physiological WSS topological skeleton features. Significant associations emerged between IMT at 60 months follow-up and the exposure to (1) high temporal variation of WSS contraction/expansion (R2 = 0.51, p < 0.05), and (2) high fixed point residence times, weighted by WSS contraction/expansion strength (R2 = 0.53, p < 0.05). These WSS topological skeleton features were statistically independent from the exposure to low WSS, a previously reported predictor of long-term restenosis, therefore representing different hemodynamic stimuli and potentially impacting differently the vascular response. This study confirms the direct association between WSS topological skeleton and markers of vascular disease, contributing to elucidate the mechanistic link between flow disturbances and clinical observations of vascular lesions