Nikolaos Stergiopoulos

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At a time of growing concern over the ethics of animal experimentation, mouse models are still an indispensable source of insight into the cardiovascular system and its most frequent pathologies. Nevertheless, reference data on the murine cardiovascular an ...

Arteries display a nonlinear anisotropic behavior dictated by the elastic properties and structural arrangement of its main constituents, elastin, collagen, and vascular smooth muscle. Elastin provides for structural integrity and for the compliance of the ...

Objective: One of the factors contributing to complications related to open repair of the aorta is the construction of a hand-sewn anastomosis. Aortic anastomotic devices (AADs), such as the intraluminal ringed graft (IRG), and the anastomotic stenting tec ...

Background: Carotid-to-femoral pulse wave velocity (c-f PWV) is commonly used to assess large artery stiffness, particularly as a surrogate of aortic stiffness. Given that c-f PWV represents the average stiffness of all main arteries along the carotid-to-femoral arterial pathway, without specifically accounting for the stiffness of the proximal aorta, we hypothesized that c-f PWV may not represent stricto sensu the stiffness of the ascending aorta (AAO), which is the main contributor to total arterial compl

The transaortic valvular pressure gradient (TPG) plays a central role in decision-making for patients suffering from severe aortic stenosis. However, the flow-dependence nature of the TPG makes the diagnosis of aortic stenosis challenging since the markers ...

Background The renin-angiotensin system (RAS) has been shown to play an active role within the erectile tissues. The aim of this narrative review is to summarize the literature addressing the pathophysiological role of RAS on erectile function. Additionall ...

Cytoskeletal rearrangement occurs in a variety of cellular processes and involves a wide spectrum of proteins. Among these, the gelsolin superfamily proteins control actin organization by severing filaments, capping filament ends and nucleating actin assembly [1]. Gelsolin is the founding member of this family, which now contains at least another six members: villin, adseverin, capG, advillin, supervillin and flightless I. In addition to their respective role in actin filament remodeling, these proteins hav

Angiotensin (Ang) II contributes to the development of atherosclerosis, while Ang-(1-7) has atheroprotective actions. Accordingly, angiotensin-converting enzyme 2 (ACE2), which breaks-down Aug 11 and forms Ang-(1-7), has been suggested as a target against ...

Plaque-prone areas are exposed to a particular hemodynamic environment characterized by a low mean shear stress value and a cyclic reversal flow. This mechanical environment, also termed oscillatory shear stress (OSS), induces the expression of several pro ...

The numerical tools to simulate blood flow in the cardiovascular system are constantly developing due to the great clinical interest and to scientific advances in mathematical models and computational power. The present work aims to address and validate ne ...

Animal models of aortic aneurysm and dissection can enhance our limited understanding of the etiology of these lethal conditions particularly because early-stage longitudinal data are scant in humans. Yet, the pathogenesis of often-studied mouse models and ...

Driven by the need for more efficient and seamless integration of physical models and data, physics -informed neural networks (PINNs) have seen a surge of interest in recent years. However, ensuring the reliability of their convergence and accuracy remains ...

Interest in patient-specific blood-flow circulation modeling has increased substantially in recent years. The availability of clinical data for geometric and elastic properties together with efficient numerical methods has now made model rendering feasible ...

PURPOSE. We report on the in vivo testing of a novel noninvasively adjustable glaucoma drainage device (AGDD), which features an adjustable outflow resistance, and assess the safety and efficiency of this implant. METHODS. Under general anesthesia, the AGD ...

Cyclic circumferential stretch and shear stress caused by pulsatile blood flow work in concert, yet are very different stimuli capable of independently mediating endothelial function by modulating eNOS expression, oxidative stress (via production of supero ...

Smooth muscle cell calcium dynamics and diameter were measured in intact pressurized rat mesenteric artery segments during vasoconstriction and vasomotion. Arteries showed a certain norepinephrine (NE) threshold (0.3-0.4 microM) for the onset of vasomotion, during a cumulative NE concentration-response curve. This was due to a necessary [Ca2+]i threshold (increase over basal level of 22.2 +/- 2.6%) to elicit oscillations. The calcium oscillations obtained were synchronous over the entire vessel length and p

Mathematical models of the arterial tree constitute a valuable tool to investigate the hemodynamics of aging and pathology. Rendering such models as patient specific could allow for the assessment of central hemodynamic variables of clinical interest. Howe ...

Aortic diastolic pressure decay (DPD) has been shown to have considerable pathophysiological relevance in the assessment of vascular health, as it is significantly affected by arterial stiffening. Nonetheless, the aortic pressure waveform is rarely availab ...

Mechanical properties of the adventitia are largely determined by the organization of collagen fibers. Measurements on the waviness and orientation of collagen, particularly at the zero-stress state, are necessary to relate the structural organization of c ...

With advancing age arteries stiffen, reducing arterial compliance and leading to the development of systolic hypertension and to a substantial increase in pulse pressure. An augmented pulse pressure can be a predictor of the development of hypertension, wh ...

Nikolaos Stergiopoulos

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A 1D model of the arterial circulation in mice

Effect of elastin degradation on carotid wall mechanics as assessed by a constituent-based biomechanical model

A systematic review and meta-analysis of the efficacy of aortic anastomotic devices

Relation of carotid-to-femoral pulse wave velocity to aortic stiffness and total arterial compliance in healthy individuals

The Impact of Left Ventricular Performance and Afterload on the Evaluation of Aortic Valve Stenosis: A 1D Mathematical Modeling Approach

Pathophysiological role of the renin-angiotensin system on erectile dysfunction

Gelsolin superfamily proteins: key regulators of cellular functions

Diminazene enhances stability of atherosclerotic plaques in ApoE-deficient mice

Transcriptional and post-transcriptional regulation of preproendothelin-1 by plaque-prone hemodynamics

Fluid Structure Interaction Simulations of Physiological Blood Flow in the Aorta

Co-localization of microstructural damage and excessive mechanical strain at aortic branches in Angiotensin-II-infused mice

Residual-based attention in physics-informed neural networks

Physiological simulation of blood flow in the aorta: comparison of hemodynamic indices as predicted by 3-D FSI, 3-D rigid wall and 1-D models

In Vivo Testing of a Novel Adjustable Glaucoma Drainage Device

Autonomous effects of shear stress and cyclic circumferential stretch regarding endothelial dysfunction and oxidative stress: an ex vivo arterial model

Calcium dynamics and vasomotion in rat mesenteric arteries

On the importance of the nonuniform aortic stiffening in the hemodynamics of physiological aging

On the similarity between aortic and carotid pressure diastolic decay: a mathematical modelling study

Experimental investigation of collagen waviness and orientation in the arterial adventitia using confocal laser scanning microscopy

Effects of reduced cyclic stretch on vascular smooth muscle cell function of pig carotids perfused ex vivo