Design and Validation of a Modular, Backdrivable Ankle Exoskeleton.

Partial-assist ankle exoskeletons have been limited by inherent trade-offs between favorable characteristics including high torque capacity, high control bandwidth, back-drivability, compliance, and low mass. Emerging quasi-direct drive actuators have a rigid transmission with a low gear ratio, enabling inherent backdrivability and compliance with accurate torque and position control. Our existing modular, backdrivable exoskeleton system () uses quasi-direct drive actuators at the hip and/or knee to deliver high assistive torques alongside low dynamic backdrive torques, enabling natural interaction with users with remnant voluntary motion.

Association Between Insomnia, Stress Events, and Other Psychosocial Factors and Incident Atrial Fibrillation in Postmenopausal Women: Insights From the Women's Health Initiative.

Background The association between psychosocial factors and atrial fibrillation (AF) is poorly understood. Methods and Results Postmenopausal women from the Women's Health Initiative were retrospectively analyzed to identify incident AF in relation to a panel of validated psychosocial exposure variables, as assessed by multivariable Cox proportional hazard regression and hierarchical cluster analysis. Among the 83 736 women included, the average age was 63.

Socioeconomic Burden of Rising Methamphetamine-Associated Heart Failure Hospitalizations in California From 2008 to 2018.

Background: Methamphetamine-associated cardiomyopathy/heart failure (MethHF) is an increasingly recognized disease entity in the context of a rising methamphetamine (meth) epidemic that most severely impacts the western United States. Using heart failure (HF) hospitalization data from the Office of Statewide Health Planning and Development, this study aimed to assess trend and disease burden of MethHF in California.

Methods: Adult patients (≥18 years old) with HF as primary hospitalization diagnosis between 2008 and 2018 were included in this study.

Infants at risk for physical disability may be identified by measures of postural control in supine.

Background: Early detection of delay or impairment in motor function is important to guide clinical management and inform prognosis during a critical window for the development of motor control in children. The purpose of this study was to investigate the ability of biomechanical measures of early postural control to distinguish infants with future impairment in motor control from their typically developing peers.

Methods: We recorded postural control from infants lying in supine in several conditions.

Comparison of Clinical Characteristics and Outcomes of Patients With Reversible Versus Persistent Methamphetamine-Associated Cardiomyopathy.

Anecdotal cases of reversible methamphetamine-associated cardiomyopathy (rMAC) have been reported, but not well understood. This study sought to determine the clinical characteristics, outcomes and predictors of reversibility among patients with rMAC as compared with patients with persistent MAC (pMAC). We retrospectively studied adult MAC patients with left ventricular ejection fraction (LVEF) ≤40% at a single center between 2004 and 2018.

Cardiac MRI T2* in Liver Transplant Candidates: Application and Performance of a Novel Imaging Technique to Identify Patients at Risk for Poor Posttransplant Cardiac Outcomes.

Background: In end-stage liver disease, alterations in iron metabolism can lead to iron overload and development of iron overload cardiomyopathy. In liver transplant candidates, evaluation for cardiac iron overload and dysfunction can help to identify candidates at increased risk for peritransplant morbidity and mortality, though recommendations for pretransplant evaluation of cardiac iron overload are not standardized. Cardiac Magnetic Resonance Imaging T2* (CMRI-T2*) is a validated method to quantify cardiac iron deposition, with normal T2* value of 20 ms or greater.

Clinical Characteristics and Outcome of Methamphetamine-Associated Pulmonary Arterial Hypertension and Dilated Cardiomyopathy.

Objectives: This study sought to characterize patients with methamphetamine-associated pulmonary arterial hypertension (MA-PAH) and cardiomyopathy (MA-CMP), to compare with MA controls (MA-CTL), users with structurally normal hearts, with the aim of identifying risk factors for these conditions.

Background: MA-PAH and MA-CMP are 2 poorly understood cardiac complications in MA users.

Methods: We retrospectively studied the clinical characteristics and outcomes of 50 MA-PAH, 296 MA-CMP, and 356 MA-CTL patients, whom we evaluated between 2010 and 2017.

A Clinical Score for Predicting Atrial Fibrillation in Patients with Cryptogenic Stroke or Transient Ischemic Attack.

Objectives: Detection of atrial fibrillation (AF) in post-cryptogenic stroke (CS) or transient ischemic attack (TIA) patients carries important therapeutic implications.

Methods: To risk stratify CS/TIA patients for later development of AF, we conducted a retrospective cohort study using data from 1995 to 2015 in the Stanford Translational Research Integrated Database Environment (STRIDE).

Results: Of the 9,589 adult patients (age ≥40 years) with CS/TIA included, 482 (5%) patients developed AF post CS/TIA.

Frequency and Associated Clinical Features of Functional Tricuspid Regurgitation in Patients With Chronic Atrial Fibrillation.

Significant functional tricuspid regurgitation (TR) can develop in some but not all patients with chronic atrial fibrillation (AF). This study sought to identify factors likely to be involved in determining the severity of TR in patients with chronic AF. In this retrospective cohort study of adult patients referred for transthoracic echocardiography for evaluation of AF between 2004 and 2015, we identified 170 patients with chronic AF in the absence of structural or known coronary heart disease.

Oxygen-Generating Biomaterials: A New, Viable Paradigm for Tissue Engineering?

There have been many attempts to provide sufficient nutrients, especially oxygen, to engineered large tissues to overcome the effects of hypoxia or poor vascularization. Delivering sufficient oxygen to the transplanted cells is one of the most critical issues that affects cell survival and correct maturation of engineered tissues. An emerging approach is using 3D scaffolds made from oxygen-generating biomaterials to tackle transport limitations deep within the engineered tissues.

Morphology impact on oxygen sensing ability of Ru(dpp)3Cl2 containing biocompatible polymers.

Especially for tissue engineering applications, the diffusion of oxygen is a critical factor affecting spatial distribution and migration of cells. The cellular oxygen demand also fluctuates depending on tissue type and growth phase. Sensors that determine dissolved oxygen levels under biological conditions provide critical metabolic information about the growing cells as well as the state of the tissue culture within the tissue scaffold.

Comparison of radionuclide angiographic synchrony analysis to echocardiography and magnetic resonance imaging for the diagnosis of arrhythmogenic right ventricular cardiomyopathy.

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heritable arrhythmia syndrome entailing a high risk of sudden cardiac death. Discernment from benign arrhythmia disorders, particularly right ventricular outflow tract ventricular tachycardia (RVOT VT), may be challenging, providing an impetus to explore alternative modalities that may facilitate evaluation of patients with suspected ARVC.

Objective: We evaluated the role of equilibrium radionuclide angiography (ERNA) as a diagnostic tool for ARVC.

Plakoglobin immunolocalization as a diagnostic test for arrhythmogenic right ventricular cardiomyopathy.

Background: A recent study using an anti-plakoglobin antibody and immunofluorescence methods in endomyocardial tissue specimens found that a marked reduction in plakoglobin staining was highly sensitive and specific for the diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC). The purpose of our study was to determine the diagnostic utility of plakoglobin immunolocalization using more standard immunoperoxidase methods suitable for clinical laboratories.

Methods: Between January 2007 and October 2010, all patients at our center with suspected ARVC underwent noninvasive and genetic testing, right ventricular (RV) angiography, electrophysiologic studies, and endomyocardial biopsy from the RV septum.

Suppression of calcium-induced repolarization heterogeneity as a mechanism of nitroglycerin's antiarrhythmic action.

This study examined whether the antifibrillatory action of nitroglycerin (NTG) is attributable to reduction in calcium-induced heterogeneity of repolarization independent of autonomic and coronary vasodilatory influences. The effects of intrapericardial (IPC) NTG on coronary blood flow, contractility, repolarization, and arrhythmia susceptibility were measured in anesthetized pigs (N = 43). Autonomic influences were minimized by vagotomy and beta-adrenergic blockade (metoprolol, 1.

Potent antifibrillatory effects of intrapericardial nitroglycerin in the ischemic porcine heart.

Objectives: We investigated the antiarrhythmic effects of intrapericardial nitroglycerin (NTG) during acute myocardial ischemia in the porcine heart.

Background: Nitroglycerin is a nitric oxide donor that exerts potent effects on the cardiovascular system. Intrapericardial administration allows investigation of pharmacologic actions on cardiac tissue in an in vivo system while minimizing the confounding influences of systemic effects.