Treatment for middle cerebral artery bifurcation aneurysms: in silico comparison of the novel Contour device and conventional flow-diverters.

Endovascular treatment has become the standard therapy for cerebral aneurysms, while the effective treatment for middle cerebral artery (MCA) bifurcation aneurysms remains a challenge. Current flow-diverting techniques with endovascular coils cover the aneurysm orifice as well as adjacent vessel branches, which may lead to branch occlusion. Novel endovascular flow disruptors, such as the Contour device (Cerus Endovascular), are of great potential to eliminate the risk of branch occlusion.

Role of blood flow in endothelial functionality: a review.

Endothelial cells, located on the surface of blood vessel walls, are constantly stimulated by mechanical forces from the blood flow. The mechanical forces, i.e.

A computational study of fluid transport characteristics in the brain parenchyma of dementia subtypes.

The cerebral environment is a complex system consisting of parenchymal tissue and multiple fluids. Dementia is a common class of neurodegenerative diseases, caused by structural damages and functional deficits in the cerebral environment. In order to better understand the pathology of dementia from a cerebral fluid transport angle and provide clearer evidence that could help differentiate between dementia subtypes, such as Alzheimer's disease and vascular dementia, we conducted fluid-structure interaction modelling of the brain using a multiple-network poroelasticity model, which considers both neuropathological and cerebrovascular factors.

A CT-based predictive model for stent-induced vessel damage: application to type B aortic dissection.

Objectives: The distal stent-induced new entry (distal SINE) is a life-threatening device-related complication after thoracic endovascular aortic repair (TEVAR). However, risk factors for distal SINE are not fully determined, and prediction models are lacking. This study aimed to establish a predictive model for distal SINE based on the preoperative dataset.

A Computational Framework to Predict Calvarial Growth: Optimising Management of Sagittal Craniosynostosis.

The neonate skull consists of several bony plates, connected by fibrous soft tissue called sutures. Premature fusion of sutures is a medical condition known as craniosynostosis. Sagittal synostosis, caused by premature fusion of the sagittal suture, is the most common form of this condition.

Should friction losses be included in an electromechanical model of a bioinspired flapping-wing micro aerial vehicle to estimate the flight energetic requirements?

The paper aims to examine the effects of mechanical losses on the performance of a bioinspired flapping-wing micro aerial vehicle (FWMAV) and ways to mitigate them by introducing a novel electromechanical model. The mathematical model captures the effect of a DC gear motor, slider-crank, flapping-wings aerodynamics, and frictional losses. The aerodynamic loads are obtained using a quasi-steady flow model.

Molecular dynamics simulation: A new way to understand the functionality of the endothelial glycocalyx.

Endothelial glycocalyx (EG) is a carbohydrate-rich layer which lines the lumen side of blood vessel walls. The EG layer is directly exposed to blood flow. The unique physiological location and its strongly coupled interaction with blood flow allow the EG layer to modulate microvascular mass transport and to sense and transmit mechanical signals from the passing blood.

Virtual Flow-T Stenting for Two Patient-Specific Bifurcation Aneurysms.

The effective treatment of wide necked cerebral aneurysms located at vessel bifurcations (WNBAs) remains a significant challenge. Such aneurysm geometries have typically been approached with Y or T stenting configurations of stents and/or flow diverters, often with the addition of endovascular coils. In this study, two WNBAs were virtually treated by a novel T-stenting technique (Flow-T) with a number of braided stents and flow-diverter devices.

Understanding the Role of Endothelial Glycocalyx in Mechanotransduction via Computational Simulation: A Mini Review.

Endothelial glycocalyx (EG) is a forest-like structure, covering the lumen side of blood vessel walls. EG is exposed to the mechanical forces of blood flow, mainly shear, and closely associated with vascular regulation, health, diseases, and therapies. One hallmark function of the EG is mechanotransduction, which means the EG senses the mechanical signals from the blood flow and then transmits the signals into the cells.

Using Sensitivity Analysis to Develop a Validated Computational Model of Post-operative Calvarial Growth in Sagittal Craniosynostosis.

Craniosynostosis is the premature fusion of one or more sutures across the calvaria, resulting in morphological and health complications that require invasive corrective surgery. Finite element (FE) method is a powerful tool that can aid with preoperative planning and post-operative predictions of craniosynostosis outcomes. However, input factors can influence the prediction of skull growth and the pressure on the growing brain using this approach.

Thrombin-Fibrinogen In Vitro Flow Model of Thrombus Growth in Cerebral Aneurysms.

Cerebral aneurysms are balloon-like structures that develop on weakened areas of cerebral artery walls, with a significant risk of rupture. Thrombi formation is closely associated with cerebral aneurysms and has been observed both before and after intervention, leading to a wide variability of outcomes in patients with the condition. The attempt to manage the outcomes has led to the development of various computational models of cerebral aneurysm thrombosis.

Multi-stage learning for segmentation of aortic dissections using a prior aortic anatomy simplification.

Aortic dissection (AD) is a life-threatening cardiovascular disease with a high mortality rate. The accurate and generalized 3-D reconstruction of AD from CT-angiography can effectively assist clinical procedures and surgery plans, however, is clinically unavaliable due to the lacking of efficient tools. In this study, we presented a novel multi-stage segmentation framework for type B AD to extract true lumen (TL), false lumen (FL) and all branches (BR) as different classes.

Exploring neurodegenerative disorders using a novel integrated model of cerebral transport: Initial results.

The (NVU) underlines the complex and symbiotic relationship between brain cells and the cerebral vasculature, and dictates the need to consider both neurodegenerative and cerebrovascular diseases under the same mechanistic umbrella. Importantly, unlike peripheral organs, the brain was thought not to contain a dedicated lymphatics system. The concept (a portmanteau of glia and lymphatic) has further emphasized the importance of cerebrospinal fluid transport and emphasized its role as a mechanism for waste removal from the central nervous system.

Sodium ion transport across the endothelial glycocalyx layer under electric field conditions: A molecular dynamics study.

In the present research, the sodium ion transport across the endothelial glycocalyx layer (EGL) under an imposed electric field is investigated, for the first time, using a series of molecular dynamics simulations. The electric field is perpendicularly imposed on the EGL with varying strengths. The sodium ion molarity difference between the inner and outer layers of EGL, Δc, is used to quantify the sodium transport in the presence of the negatively charged glycocalyx sugar chains.

Finite element evaluations of the mechanical properties of polycaprolactone/hydroxyapatite scaffolds by direct ink writing: Effects of pore geometry.

Osteochondral (OC) defects usually involve the damage of both the cartilage and its underneath subchondral bone. In recent years, tissue engineering (TE) has become the most promising method that combines scaffolds, growth factors, and cells for the repair of OC defects. An ideal OC scaffold should have a gradient structure to match the hierarchical mechanical properties of natural OC tissue.

On the Validation of a Multiple-Network Poroelastic Model Using Arterial Spin Labeling MRI Data.

The Multiple-Network Poroelastic Theory (MPET) is a numerical model to characterize the transport of multiple fluid networks in the brain, which overcomes the problem of conducting separate analyses on individual fluid compartments and losing the interactions between tissue and fluids, in addition to the interaction between the different fluids themselves. In this paper, the blood perfusion results from MPET modeling are partially validated using cerebral blood flow (CBF) data obtained from arterial spin labeling (ASL) magnetic resonance imaging (MRI), which uses arterial blood water as an endogenous tracer to measure CBF. Two subjects-one healthy control and one patient with unilateral middle cerebral artery (MCA) stenosis are included in the validation test.

Membrane Deformation of Endothelial Surface Layer Interspersed with Syndecan-4: A Molecular Dynamics Study.

The lipid membrane of endothelial cells plays a pivotal role in maintaining normal circulatory system functions. To investigate the response of the endothelial cell membrane to changes in vascular conditions, an atomistic model of the lipid membrane interspersed with Syndecan-4 core protein was established based on experimental observations and a series of molecular dynamics simulations were undertaken. The results show that flow results in continuous deformation of the lipid membrane, and the degree of membrane deformation is not in monotonic relationship with the environmental changes (either the changes in blood velocity or the alteration of the core protein configuration).

Principal mode of Syndecan-4 mechanotransduction for the endothelial glycocalyx is a scissor-like dimer motion.

Aim: Endothelial glycocalyx (EG) plays a pivotal role in a plethora of diseases, like cardiovascular and renal diseases. One hallmark function of the EG as a mechanotransducer which transmits mechanical signals into cytoplasm has been documented for decades. However, the basic question - how the glycocalyx transmits the flow shear stress- is unanswered so far.

Microvascular ion transport through endothelial glycocalyx layer: new mechanism and improved Starling principle.

Ion transport through the endothelial glycocalyx layer is closely associated with many vascular diseases. Clarification of ion behaviors around the endothelial glycocalyx layer under varying circumstances will benefit pathologies related to cardiovascular and renal diseases. In this research, a series of large-scale molecular dynamics simulations are conducted to study the response of ion transport to the changing blood flow velocity and the shedding of endothelial glycocalyx sugar chains.

Effect of the Mixing Region Geometry and Collector Distance on Microbubble Formation in a Microfluidic Device Coupled with ac-dc Electric Fields.

In this work, we report a significant advance in the preparation of monodisperse microbubbles using a combination of microfluidic and electric field technologies. Microbubbles have been employed in various fields such as biomedical engineering, water purification, and food engineering. Many techniques have been investigated for their preparation.

Disturbed flow induces a sustained, stochastic NF-κB activation which may support intracranial aneurysm growth in vivo.

Intracranial aneurysms are associated with disturbed velocity patterns, and chronic inflammation, but the relevance for these findings are currently unknown. Here, we show that (disturbed) shear stress induced by vortices is a sufficient condition to activate the endothelial NF-kB pathway, possibly through a mechanism of mechanosensor de-activation. We provide evidence for this statement through in-vitro live cell imaging of NF-kB in HUVECs exposed to different flow conditions, stochastic modelling of flow induced NF-kB activation and induction of disturbed flow in mouse carotid arteries.

General Computational Methodology for Modeling Electrohydrodynamic Flows: Prediction and Optimization Capability for the Generation of Bubbles and Fibers.

The application of an electric field on a fluid in motion gives rise to unique features and flow manipulation capabilities. Technologies ranging from bubble formation, droplet generation, fiber spinning, and many others are predicated on this type of flows, often referred to as Electrohydrodynamics (EHD). In this paper, we present a numerical methodology that allows for the modeling of such processes in a generalized way.

Understanding endothelial glycocalyx function under flow shear stress from a molecular perspective.

Background: The endothelial glycocalyx plays a pivotal role in regulating blood flow, filtering blood components, sensing and transducing mechanical signals. These functions are intimately related to its dynamics at the molecular level.

Objective: The objective of this research is to establish the relationship between the functions of the endothelial glycocalyx and its dynamics at the molecular level.

Characterizing and Modeling Bone Formation during Mouse Calvarial Development.

The newborn mammalian cranial vault consists of five flat bones that are joined together along their edges by soft fibrous tissues called sutures. Early fusion of these sutures leads to a medical condition known as craniosynostosis. The mechanobiology of normal and craniosynostotic skull growth is not well understood.

Reducing Salt Intake and Exercising Regularly: Implications From Molecular Dynamics Simulations of Endothelial Glycocalyx.

It is widely accepted that salt intake reduction and regular exercise is a healthy lifestyle, which can prevent cardiovascular diseases (CVD). Meanwhile, there is evidence that the endothelial glycocalyx layer (EGL) is related to CVD. However, how such a healthy lifestyle helps to prevent CVD via the function of the EGL has not been scientifically established.