Estimation of In Vivo Human Carotid Artery Elasticity Using Arterial Dispersion Ultrasound Vibrometry.

Objective: Arterial stiffening serves as an early indicator for a variety of cardiovascular diseases. Arterial Dispersion Ultrasound Vibrometry (ADUV) is a method that leverages acoustic radiation force to stimulate arterial wall motion, assess wave propagation characteristics, and subsequently calculate the arterial shear modulus. Previously, we introduced an inversion technique based on a guided cylindrical wave model, which proved effective in rubber tube phantom experiments.

An empirical model for world record running speeds with distance, age, and sex: anaerobic and aerobic contributions to performance.

The objective of this study is to derive mathematical equations that closely describe published data on world record running speed as a function of distance, age, and sex. Running speed declines with increasing distance and age. Over long distances, where aerobic metabolism is dominant, speed declines in proportion to the logarithm of distance.

Attenuation of Nerve Agent Induced Neurodegenerative and Neuroinflammatory Changes in Rats with New Combination Treatment of Galantamine, Atropine and Midazolam.

Acute nerve agent exposure can kill a person within minutes or produce multiple neurotoxic effects and subsequent brain damage with potential long-term adverse outcomes. Recent abuse of nerve-agents on Syrian civilians, during Japan terrorist attacks, and personal assassinations in the UK, and Malaysia indicate their potential threat to world population. Existing nerve agent antidotes offer only incomplete protection especially, if the treatment is delayed.

Designing an implementation strategy to increase health-related social needs screening: Applying the PRISM framework in a resource-limited clinical setting.

Despite growing acceptability of health-related social needs (HRSN) screening and increasing policy incentives for adoption, clinical implementation of HRSN screening remains low. HRSN screening has been particularly difficult for Community Health Centers (CHCs), which have limited resources to implement and sustain new workflows. While CHCs provide care to patients with disproportionately high levels of unmet social needs, identifying HRSN screening implementation strategies that take CHC-specific contexts into account remains elusive.

The dependence of maximum oxygen uptake and utilization (V̇O max) on hemoglobin-oxygen affinity and altitude.

Oxygen transport from the lungs to peripheral tissue is dependent on the affinity of hemoglobin for oxygen. Recent experimental data have suggested that the maximum human capacity for oxygen uptake and utilization (V̇O max) at sea level and altitude (~3000 m) is sensitive to alterations in hemoglobin-oxygen affinity. However, the effect of such alterations on V̇O max at extreme altitudes remains largely unknown due to the rarity of mutations affecting hemoglobin-oxygen affinity.

Attenuated cardiac autonomic function in humans with high-affinity hemoglobin and compensatory polycythemia.

During hypoxic exposure, humans with high-affinity hemoglobin (and compensatory polycythemia) have blunted increases in heart rate compared with healthy humans with typical oxyhemoglobin dissociation curves. This response may be associated with altered autonomic control of heart rate. Our hypothesis-generating study aimed to investigate cardiac baroreflex sensitivity and heart rate variability among nine humans with high-affinity hemoglobin [6 females, O partial pressure at 50% [Formula: see text] (P) = 16 ± 1 mmHg] compared with 12 humans with typical affinity hemoglobin (6 F, P = 26 ± 1 mmHg).

Full waveform inversion for arterial viscoelasticity.

. Arterial viscosity is emerging as an important biomarker, in addition to the widely used arterial elasticity. This paper presents an approach to estimate arterial viscoelasticity using shear wave elastography (SWE).

Sociocultural Costs of the Long-term COVID-19 Outbreak in Bangladesh: A Systematic Review.

Beyond the physical transmission of COVID-19, the pandemic has had far-reaching consequences in Bangladesh, including social and cultural implications. This review paper aimed at identifying and synthesizing the costs of COVID-19 on sociocultural issues in Bangladesh. For this purpose, we conducted a systematic search in MEDLINE, PubMed, ProQuest, Web of Science, Scopus and Google Scholar up to August 2021.

Evaluating the Teaching Health Center Graduate Medical Education Model at 10 Years: Practice-Based Outcomes and Opportunities.

Background: Since 2011, the Teaching Health Center Graduate Medical Education (THC GME) program has sought to expand access to care by training residents in safety net settings.

Objective: To examine impact on physician scope, location, and patient population served using a unique data set.

Methods: Using 2017-2020 data from the American Board of Family Medicine National Graduate Survey, we compared demographics, practice location, populations served, and scope of practice between graduates of THC GME programs and graduates of other family medicine programs.

Measurement of wave propagation through a tube using dual transducers for elastography in arteries.

Measuring waves induced with acoustic radiation force (ARF) in arteries has been studied over the last decade. To date, it remains a challenge to quantitatively assess the local arterial biomechanical properties. The cylindrical shape and waveguide behavior of waves propagating in the arterial wall pose complexities to determining the mechanical properties of the artery.

Full wave simulation of arterial response under acoustic radiation force.

With the ultimate goal of estimating arterial viscoelasticity using shear wave elastography, this paper presents a practical methodology to simulate the response of a human carotid artery under acoustic radiation force (ARF). The artery is idealized as a nearly incompressible viscoelastic hollow cylinder submerged in incompressible, inviscid fluid. For this idealization, we develop a multi-step methodology for efficient computation of three-dimensional response under complex ARF excitation, while capturing the fluid-structure interaction between the arterial wall and the surrounding fluid.

The influence of acoustic radiation force beam shape and location on wave spectral content for arterial dispersion ultrasound vibrometry.

. Arterial dispersion ultrasound vibrometry (ADUV) relies on the use of guided waves in arterial geometries for shear wave elastography measurements. Both the generation of waves through the use of acoustic radiation force (ARF) and the techniques employed to infer the speed of the resulting wave motion affect the spectral content and accuracy of the measurement.

Muscle oxygenation during normoxic and hypoxic cycling exercise in humans with high-affinity haemoglobin.

New Findings: What is the central question of this study? Do humans with high-affinity haemoglobin (HAH) demonstrate attenuated skeletal muscle deoxygenation during normoxic and hypoxic exercise? What is the main finding and its importance? Examination of near-infrared spectroscopy-derived muscle oxygenation profiles suggests that fractional oxygen extraction is blunted during hypoxic exercise in humans with HAH compared with control subjects. However, muscle tissue oxygen saturation levels were higher in humans with HAH during exercise in normoxia compared with control subjects. These alterations in fractional oxygen extraction in humans with HAH might influence blood flow regulation and exercise capacity during hypoxia.

Functional implications of microvascular heterogeneity for oxygen uptake and utilization.

In the vascular system, an extensive network structure provides convective and diffusive transport of oxygen to tissue. In the microcirculation, parameters describing network structure, blood flow, and oxygen transport are highly heterogeneous. This heterogeneity can strongly affect oxygen supply and organ function, including reduced oxygen uptake in the lung and decreased oxygen delivery to tissue.

Predictors of loss to follow-up from HIV antiretroviral therapy in Namibia.

Despite progress on population-level HIV viral suppression, unknown outcomes amongst people who have initiated antiretroviral therapy (ART) in low- and middle-income countries, commonly referred to as loss to follow-up (LTFU), remains a barrier. The mean global estimate of LTFU is 20%, exceeding the World Health Organization target of <15%. Pervasive predictors associated with LTFU include younger age, low body mass index, low CD4 count, advanced HIV clinical stage and certain ART regimens.

Toward improved accuracy in shear wave elastography of arteries through controlling the arterial response to ultrasound perturbation in-silico and in phantoms.

Dispersion-based inversion has been proposed as a viable direction for materials characterization of arteries, allowing clinicians to better study cardiovascular conditions using shear wave elastography. However, these methods rely onknowledge of the vibrational modes dominating the propagating waves induced by acoustic radiation force excitation: differences between anticipated and real modal content are known to yield errors in the inversion. We seek to improve the accuracy of this process by modeling the artery as a fluid-immersed cylindrical waveguide and building an analytical framework to prescribe radiation force excitations that will selectively excite certain waveguide modes using ultrasound acoustic radiation force.

Information transmission in a two-step cascade: interplay of activation and repression.

We present an information-theoretic formalism to study signal transduction in four architectural variants of a model two-step cascade with increasing input population. Our results categorize these four types into two classes depending upon the effect of activation and repression on mutual information, net synergy, and signal-to-noise ratio. Using the Gaussian framework and linear noise approximation, we derive the analytic expressions for these metrics to establish their underlying relationships in terms of the biochemical parameters.

Analysis of flow resistance in the pulmonary arterial circulation: implications for hypoxic pulmonary vasoconstriction.

Hypoxic pulmonary vasoconstriction (HPV) plays an essential role in distributing blood in the lung to enhance ventilation-perfusion matching and blood oxygenation. In this study, a theoretical model of the pulmonary vasculature is used to predict the effects of vasoconstriction over specified ranges of vessel diameters on pulmonary vascular resistance (PVR). The model is used to evaluate the ability of hypothesized mechanisms of HPV to account for observed levels of PVR elevation during hypoxia.

Multimodal guided wave inversion for arterial stiffness: methodology and validation in phantoms.

Arterial stiffness is an important biomarker for many cardiovascular diseases. Shear wave elastography is a recent technique aimed at estimating local arterial stiffness using guided wave inversion (GWI), i.e.

COVID-19 vaccine rumors and conspiracy theories: The need for cognitive inoculation against misinformation to improve vaccine adherence.

Introduction: Rumors and conspiracy theories, can contribute to vaccine hesitancy. Monitoring online data related to COVID-19 vaccine candidates can track vaccine misinformation in real-time and assist in negating its impact. This study aimed to examine COVID-19 vaccine rumors and conspiracy theories circulating on online platforms, understand their context, and then review interventions to manage this misinformation and increase vaccine acceptance.

The Oxygen Cascade During Exercise in Health and Disease.

The oxygen transport cascade describes the physiological steps that bring atmospheric oxygen into the body where it is delivered and consumed by metabolically active tissue. As such, the oxygen cascade is fundamental to our understanding of exercise in health and disease. Our narrative review will highlight each step of the oxygen transport cascade from inspiration of atmospheric oxygen down to mitochondrial consumption in both healthy active males and females along with clinical conditions.

Shear wave dispersion analysis of incompressible waveguides.

A suite of methodologies is presented to compute shear wave dispersion in incompressible waveguides encountered in biomedical imaging; plate, tube, and general prismatic waveguides, all immersed in an incompressible fluid, are considered in this effort. The developed approaches are based on semi-analytical finite element methods in the frequency domain with a specific focus on the complexities associated with the incompressibility of the solid media as well as the simplification facilitated by the incompressibility of the surrounding fluid. The proposed techniques use the traditional idea of selective reduced integration for the solid medium and the more recent idea of perfectly matched discrete layers for the surrounding fluid.

Effects of impaired microvascular flow regulation on metabolism-perfusion matching and organ function.

Impaired tissue oxygen delivery is a major cause of organ damage and failure in critically ill patients, which can occur even when systemic parameters, including cardiac output and arterial hemoglobin saturation, are close to normal. This review addresses oxygen transport mechanisms at the microcirculatory scale, and how hypoxia may occur in spite of adequate convective oxygen supply. The structure of the microcirculation is intrinsically heterogeneous, with wide variations in vessel diameters and flow pathway lengths, and consequently also in blood flow rates and oxygen levels.