Biology subjects

Cavallero, S.

Publications and source records attributed to Cavallero, S..

5 recordsLinked to original sources

bioRxiv2023

The trade-off between growth and risk in Kelly's gambling and beyond

We study a generalization of Kellys horse model to situations where gambling on horses other than the winning horse does not lead to a complete loss of the investment. In such a case, the odds matrix is non-diagonal, a case which is of special interest for biological applications. We derive a trade-off for this model between the mean growth rate and the volatility as a proxy for risk. We show that this trade-off is related to a game-theoretic formulation of this problem developed previously. Since the effect of fluctuations around the average growth rate is asymmetric, we also study how the risk-growth trade-off is modified when risk is evaluated more accurately by the probability of the gambles ruin.

biophysics↗

bioRxiv2023

Exercise Mitigates Flow Recirculation and Activates Mechanosensitive Transcriptome to Uncover Endothelial SCD1-Catalyzed Anti-Inflammatory Metabolites

Exercise modulates vascular plasticity in multiple organ systems; however, the metabolomic transducers underlying exercise and vascular protection in the disturbed flow-prone vasculature remain under-investigated. We simulated exercise-augmented pulsatile shear stress (PSS) to mitigate flow recirculation in the lesser curvature of the aortic arch. When human aortic endothelial cells (HAECs) were subjected to PSS ({tau}ave = 50 dyne{middle dot}cm-2, {partial}{tau}/{partial}t = 71 dyne{middle dot}cm-2{middle dot}s-1, 1 Hz), untargeted metabolomic analysis revealed that Stearoyl-CoA Desaturase (SCD1) in the endoplasmic reticulum (ER) catalyzed the fatty acid metabolite, oleic acid (OA), to mitigate inflammatory mediators. Following 24 hours of exercise, wild-type C57BL/6J mice developed elevated SCD1-catalyzed lipid metabolites in the plasma, including OA and palmitoleic acid (PA). Exercise over a 2-week period increased endothelial SCD1 in the ER. Exercise further modulated the time-averaged wall shear stress (TAWSS or{tau} ave) and oscillatory shear index (OSIave), upregulated Scd1 and attenuated VCAM1 expression in the disturbed flow-prone aortic arch in Ldlr-/- mice on high-fat diet but not in Ldlr-/-Scd1EC-/- mice. Scd1 overexpression via recombinant adenovirus also mitigated ER stress. Single cell transcriptomic analysis of the mouse aorta revealed interconnection of Scd1 with mechanosensitive genes, namely Irs2, Acox1 and Adipor2 that modulate lipid metabolism pathways. Taken together, exercise modulates PSS ({tau}ave and OSIave) to activate SCD1 as a metabolomic transducer to ameliorate inflammation in the disturbed flow-prone vasculature.

physiology↗

bioRxiv2021

Computational Simulation of 4-D Micro-Circular Network in Zebrafish Tail Amputation and Regeneration

Wall shear stress (WSS) in the micro-vasculature contributes to biomechanical cues that regulate mechanotransduction underlying vascular development, regeneration, and homeostasis. We hereby elucidate the interplay between hemodynamic shear forces and luminal remodeling in response to vascular injury and regeneration in the zebrafish model of tail amputation. Using the transgenic Tg(fli1:eGFP; Gata1:ds-red) line, we were able to track the enhanced green-fluorescent protein (eGFP)-labeled endothelial lining of the 3-D microvasculature for post-image segmentation and reconstruction of fluid domain for computational fluid dynamics (CFD) simulation. At 1 day post amputation (dpa), dorsal aorta (DA) and posterior cardinal vein (PCV) were severed, and vasoconstriction developed in the dorsal longitudinal anastomotic vessel (DLAV) with a concomitant increase in WSS in the segmental vessels (SV) proximal to the amputation site and a decrease in WSS in SVs distal to amputation. Simultaneously, we observed angiogenesis commencing at the tips of the amputated DLAV and PCV where WSS was minimal in the absence of blood flow. At 2 dpa, vasodilation occurred in a pair of SVs proximal to amputation, resulting in increased flow rate and WSS, whereas in the SVs distal to amputation, WSS normalized to the baseline. At 3 dpa, the flow rate in the arterial SV proximal to amputation continued to rise and merged with DLAV that formed a new loop with PCV. Thus, our CFD modeling uncovered a well-coordinated micro-vascular adaptation process following tail amputation, accompanied by the rise and fall of WSS and dynamic changes in flow rate during vascular regeneration.

bioengineering↗

bioRxiv2020

Liver Electrical Impedance Tomography for Early Identification of Fatty Infiltrate in Obesity

Non-alcoholic fatty liver disease (NAFLD) is endemic in developed countries and is one of the most common causes of cardiometabolic diseases in overweight/obese individuals. While liver biopsy or magnetic resonance imaging (MRI) is the current gold standard to diagnose NAFLD, the former is prone to bleeding and the latter is costly. We hereby demonstrated liver electrical impedance tomography (EIT) as a non-invasive and portable detection method for fatty infiltrate. We enrolled 19 subjects (15 females and 4 males; 27 to 74 years old) to undergo liver MRI scans, followed by EIT measurements via a multi-electrode array. The liver MRI scans provided subject-specific a priori knowledge of the liver boundary conditions for segmentation and EIT reconstruction, and the 3-D multi-echo MRI data quantified liver proton-density fat fraction (PDFF%) as a recognized reference standard for validating liver fat infiltrate. Using acquired voltage data and the reconstruction algorithm for the EIT imaging, we computed the absolute conductivity distribution of abdomen in 2-D. Correlation analyses were performed to compare the individual EIT conductivity vs. MRI PDFF with their demographics in terms of gender, BMI (kg{middle dot}m-2), age (years), waist circumference (cm), height (cm), and weight (kg). Our results indicate that EIT conductivity (S{middle dot}m-1) and liver MRI for PDFF were not correlated with the demographics, whereas the decrease in EIT conductivity was correlated with the increase in MRI PDFF (R = - 0.69, p= 0.003). Thus, EIT conductivity holds promise for developing a non-invasive, portable, and quantitative method to detect fatty liver disease.

bioengineering↗

bioRxiv2020

Vascular Injury Changes Topology of Vessel Network to Adapt to Partition of Blood Flow for New Arteriovenous Specification

Within vascular networks, wall shear stress (WSS) modulates endothelial cell proliferation and arteriovenous specification. Mechano-responsive signaling pathways enable vessels within a connected network to structurally adapt to properly partition blood flow between different parts of organ systems. Here, we study vascular regeneration in a zebrafish model system, performing tail amputation of the Dorsal Aorta (DA)-Posterior Cardinal Vein (PCV) embryonic circulatory loop (ECL) at 3 days post fertilization (dpf). Following severing the ECL, the topology of the micro-circular network is reorganized to engender local increase in blood flow and peak WSS in the closest Segmental Artery (SeA) to the amputation site. Remodeling of this artery increases its radius, and blood flow. These hemodynamic WSS cues activate post-angiogenic Notch-ephrinb2 signaling to guide network reconnection and restore microcirculation. Gain- and loss-of-function analyses of Notch and ephrinb2 pathways, manipulations of WSS by modulating myocardial contractility and blood viscosity directly implicate that hemodynamically activated post-angiogenic Notch-ephrinb2 signaling guides network reconnection and restore microcirculation. Taken together, amputation of the DA-PCV loop induces changes in microvascular topology to partition blood flow and increase WSS-mediated Notch-ephrinb2 pathway, driving the new DLAV-PCV loop formation for restoring local microcirculation.

molecular biology↗