scholarly journals Quantifying Age-Related Differences of Ankle Mechanical Properties Using a Robotic Device

Robotics ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 96 ◽  
Author(s):  
Martelli ◽  
Taborri ◽  
Del Prete ◽  
Palermo ◽  
Rossi
Keyword(s):  
Mechanical Properties ◽  
Mechanical Impedance ◽  
Ankle Impedance ◽  
Age Related ◽  
Lower Accuracy ◽  
Adults And Children ◽  
Output System ◽  
Kinematic Performance ◽  
Robotic Devices ◽  
And Inversion

A deep analysis of ankle mechanical properties is a fundamental step in the design of an exoskeleton, especially if it is to be suitable for both adults and children. This study aims at assessing age-related differences of ankle properties using pediAnklebot. To achieve this aim, we enrolled 16 young adults and 10 children in an experimental protocol that consisted of the evaluation of ankle mechanical impedance and kinematic performance. Ankle impedance was measured by imposing stochastic torque perturbations in dorsi-plantarflexion and inversion-eversion directions. Kinematic performance was assessed by asking participants to perform a goaldirected task. Magnitude and anisotropy of impedance were computed using a multipleinput multiple-output system. Kinematic performance was quantified by computing indices of accuracy, smoothness, and timing. Adults showed greater magnitude of ankle impedance in both directions and for all frequencies, while the anisotropy was higher in children. By analyzing kinematics, children performed movements with lower accuracy and higher smoothness, while no differences were found for the duration of the movement. In addition, adults showed a greater ability to stop the movement when hitting the target. These findings can be useful to a proper development of robotic devices, as well as for implementation of specific training programs.

Instrumented Walkway for Estimation of the Ankle Impedance in Dorsiflexion-Plantarflexion and Inversion-Eversion During Standing and Walking

2015 ◽  
Author(s):  
Evandro M. Ficanha ◽  
Guilherme Ribeiro ◽  
Mohammad Rastgaar Aagaah
Keyword(s):  
Degrees Of Freedom ◽  
Force Plate ◽  
Mechanical Impedance ◽  
Standing Position ◽  
Camera System ◽  
Ankle Impedance ◽  
System A ◽  
Human Ankle ◽  
Applied Forces ◽  
And Inversion

This paper describes in detail the fabrication of an instrumented walkway for estimation of the ankle mechanical impedance in both dorsiflexion-plantarflexion (DP) and in inversion-eversion (IE) directions during walking in arbitrary directions and standing. The platform consists of two linear actuators, each capable of generating ±351.3 N peak force that are mechanically coupled to a force plate using Bowden cables. The applied forces cause the force plate to rotate in two degrees of freedom (DOF) and transfer torques to the human ankle to generate DP and IE rotations. The relative rotational motion of the foot with respect to the shin is recorded using a motion capture camera system while the forces applied to the foot are measured with the force plate, from which the torques applied to the ankle are calculated. The analytical methods required for the estimation of the ankle torques, rotations, and impedances are presented. To validate the system, a mockup with known stiffness was used, and it was shown that the developed system was capable of properly estimating the stiffness of the mockup in two DOF with less than 5% error. Also, a preliminary experiment with a human subject in standing position was performed, and the estimated quasi-static impedance of the ankle was estimated at 319 Nm/rad in DP and 119 Nm/rad in IE.

scholarly journals Age-related differences in monocyte DNA methylation and immune function in healthy Kenyan adults and children

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Katherine R. Dobbs ◽  
Paula Embury ◽  
Emmily Koech ◽  
Sidney Ogolla ◽  
Stephen Munga ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Young Adults ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Innate Immune ◽  
Inflammatory Gene Expression ◽  
Cpg Sites ◽  
Age Related ◽  
Adults And Children

Abstract Background Age-related changes in adaptive and innate immune cells have been associated with a decline in effective immunity and chronic, low-grade inflammation. Epigenetic, transcriptional, and functional changes in monocytes occur with aging, though most studies to date have focused on differences between young adults and the elderly in populations with European ancestry; few data exist regarding changes that occur in circulating monocytes during the first few decades of life or in African populations. We analyzed DNA methylation profiles, cytokine production, and inflammatory gene expression profiles in monocytes from young adults and children from western Kenya. Results We identified several hypo- and hyper-methylated CpG sites in monocytes from Kenyan young adults vs. children that replicated findings in the current literature of differential DNA methylation in monocytes from elderly persons vs. young adults across diverse populations. Differentially methylated CpG sites were also noted in gene regions important to inflammation and innate immune responses. Monocytes from Kenyan young adults vs. children displayed increased production of IL-8, IL-10, and IL-12p70 in response to TLR4 and TLR2/1 stimulation as well as distinct inflammatory gene expression profiles. Conclusions These findings complement previous reports of age-related methylation changes in isolated monocytes and provide novel insights into the role of age-associated changes in innate immune functions.

scholarly journals Age related extracellular matrix and interstitial cell phenotype in pulmonary valves

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Shaohua Wu ◽  
Vikas Kumar ◽  
Peng Xiao ◽  
Mitchell Kuss ◽  
Jung Yul Lim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Extracellular Matrix ◽  
Heart Valve ◽  
Cell Phenotype ◽  
Primary Concern ◽  
Ross Operation ◽  
Age Related ◽  
Cardiovascular Morbidity And Mortality ◽  
Extracellular Matrix Components ◽  
Matrix Components

AbstractHeart valve disease is a common manifestation of cardiovascular disease and is a significant cause of cardiovascular morbidity and mortality worldwide. The pulmonary valve (PV) is of primary concern because of its involvement in common congenital heart defects, and the PV is usually the site for prosthetic replacement following a Ross operation. Although effects of age on valve matrix components and mechanical properties for aortic and mitral valves have been studied, very little is known about the age-related alterations that occur in the PV. In this study, we isolated PV leaflets from porcine hearts in different age groups (~ 4–6 months, denoted as young versus ~ 2 years, denoted as adult) and studied the effects of age on PV leaflet thickness, extracellular matrix components, and mechanical properties. We also conducted proteomics and RNA sequencing to investigate the global changes of PV leaflets and passage zero PV interstitial cells in their protein and gene levels. We found that the size, thickness, elastic modulus, and ultimate stress in both the radial and circumferential directions and the collagen of PV leaflets increased from young to adult age, while the ultimate strain and amount of glycosaminoglycans decreased when age increased. Young and adult PV had both similar and distinct protein and gene expression patterns that are related to their inherent physiological properties. These findings are important for us to better understand the physiological microenvironments of PV leaflet and valve cells for correctively engineering age-specific heart valve tissues.

Monkey Model for IgE-Mediated Otitis Media with Effusion

1983 ◽  
Vol 92 (6_suppl) ◽  
pp. 30-30
Author(s):  
R. A. Friedman ◽  
W. J. Doyle ◽  
J. Fagin ◽  
C. D. Bluestone ◽  
P. Fireman
Keyword(s):  
Otitis Media With Effusion ◽  
Challenge Test ◽  
Complement C3 ◽  
Monkey Model ◽  
Age Related ◽  
Additional Funding ◽  
Adults And Children ◽  
Total Complement ◽  
Invasive Techniques ◽  
Cellular Components

Allergic and other immune mechanisms have been suggested as important in the etiology and pathogenesis of OME, and both humoral and cellular components of the immune response have been identified in MEEs obtained from patients with OME. Yet, specific and direct documentation of an immune basis for OME has not been forthcoming. To establish a causal relationship between an immune hypersensitivity and middle ear pathophysiology, a provocative intranasal antigen challenge test has been designed using the nine-step inflation-deflation tympanometric test for ET dysfunction. These initial studies were undertaken by OMRC personnel in association with the allergy and immunology service. Subsequently, on the basis of the preliminary observations additional funding was obtained (NIAID AI 19262) to confirm and extend these studies to document antigen-induced ET dysfunction in allergic adults and children, and to establish a clinical relevance for antigen-induced ET dysfunction. Because questions concerning the etiology and pathogenesis required invasive techniques and are not suitable in humans, a monkey animal model has also been developed. Our future plans will be to further develop the monkey model of OME employing IgE and other immune reactions in monkeys with normal ET function, or with compromised, surgically created ET function. The experimental MEE will be assayed for immune components, including IgA and its secretory piece; IgG, IgM, and IgE, total complement; C3, C4, and cells including polymorphonuclear leukocytes, eosinophils, and lymphocytes (both T and B cells). Since OME is mainly a disease of the young child, it is essential that age-related differences be explored in each aspect of our experimental model. The reversal and prevention of ET dysfunction and/or OME with several drugs, including cromolyn, steroids, and antihistamines, will be studied in humans and in the monkey model.

Ageing Changes in the Tensile Properties of Tendons: Influence of Collagen Fibril Volume Fraction

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
K. L. Goh ◽  
D. F. Holmes ◽  
H.-Y. Lu ◽  
S. Richardson ◽  
K. E. Kadler ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Collagen Fibril ◽  
Volume Fraction ◽  
Area Fraction ◽  
Sectional Area ◽  
Cross Sectional ◽  
P Values ◽  
Age Related ◽  
Fibril Diameter ◽  
Age Related Changes

Connective tissues are biological composites comprising of collagen fibrils embedded in (and reinforcing) the hydrated proteoglycan-rich (PG) gel within the extracellular matrices (ECMs). Age-related changes to the mechanical properties of tissues are often associated with changes to the structure of the ECM, namely, fibril diameter. However, quantitative attempts to correlate fibril diameter to mechanical properties have yielded inconclusive evidence. Here, we described a novel approach that was based on the rule of mixtures for fiber composites to evaluate the dependence of age-related changes in tendon tensile strength (σ) and stiffness (E) on the collagen fibril cross-sectional area fraction (ρ), which is related to the fibril volume fraction. Tail tendons from C57BL6 mice from age groups 1.6–35.3months old were stretched to failure to determine σ and E. Parallel measurements of ρ as a function of age were made using transmission electron microscopy. Mathematical models (rule of mixtures) of fibrils reinforcing a PG gel in tendons were used to investigate the influence of ρ on ageing changes in σ and E. The magnitudes of σ, E, and ρ increased rapidly from 1.6monthsto4.0months (P-values <0.05) before reaching a constant (age independent) from 4.0monthsto29.0months (P-values >0.05); this trend continued for E and ρ (P-values >0.05) from 29.0monthsto35.3months, but not for σ, which decreased gradually (P-values <0.05). Linear regression analysis revealed that age-related changes in σ and E correlated positively to ρ (P-values <0.05). Collagen fibril cross-sectional area fraction ρ is a significant predictor of ageing changes in σ and E in the tail tendons of C57BL6 mice.

scholarly journals Interpretation of the Directional Properties of Voluntarily Modulated Human Ankle Mechanical Impedance

2010 ◽  
Author(s):  
Patrick Ho ◽  
Hyunglae Lee ◽  
Mohammad A. Rastgaar ◽  
Hermano Igo Krebs ◽  
Neville Hogan
Keyword(s):  
Muscle Activation ◽  
Mechanical Impedance ◽  
In Vivo Studies ◽  
General Representation ◽  
Quantitative Characterization ◽  
Ankle Impedance ◽  
Human Ankle ◽  
Electromyographic Recording

This article presents the results of two in-vivo studies providing measurements of human static ankle mechanical impedance. Accurate measurements of ankle impedance when muscles were voluntarily activated were obtained using a therapeutic robot, Anklebot, and an electromyographic recording system. Important features of ankle impedance, and their variation with muscle activity, are discussed, including magnitude, symmetry and directions of minimum and maximum impedance. Voluntary muscle activation has a significant impact on ankle impedance, increasing it by up to a factor of three in our experiments. Furthermore, significant asymmetries and deviations from a linear two-spring model are present in many subjects, indicating that ankle impedance has a complex and individually idiosyncratic structure. We propose the use of Fourier series as a general representation, providing both insight and a precise quantitative characterization of human static ankle impedance.

scholarly journals Decorin expression is important for age-related changes in tendon structure and mechanical properties

2013 ◽  
Vol 32 (1) ◽  
pp. 3-13 ◽  
Author(s):  
Andrew A. Dunkman ◽  
Mark R. Buckley ◽  
Michael J. Mienaltowski ◽  
Sheila M. Adams ◽  
Stephen J. Thomas ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Age Related ◽  
Age Related Changes

Modelling Age Differences in Isometric Elbow Flexion Using Hill's Three-Element Visco-Elastic Model

1993 ◽  
Vol 37 (2) ◽  
pp. 202-205
Author(s):  
R. Darin Ellis ◽  
Kentaro Kotani
Keyword(s):  
Mechanical Properties ◽  
Steady State ◽  
Age Differences ◽  
Elbow Flexion ◽  
Model Parameters ◽  
Elastic Model ◽  
Tissue Elasticity ◽  
Age Related ◽  
Complex Models ◽  
State Force

A visco-elastic model of the mechanical properties of muscle was used to describe age-differences in the buildup of force in isometric elbow flexion. Given information from the literature on age-related physiological changes, such as decreasing connective-tissue elasticity, one would expect changes in the mechanical properties of skeletal muscle and their related model parameters. Force vs. time curves were obtained for 7 young (aged 21–27) and 7 old (aged 69–83) female subject. There were significant age group differences in steady-state force level and the best fitting model parameters. In particular, the viscous damping element of the model plays a large role in describing the increased time to reach steady-state force levels in the older subject group. Implications of this research include incorporating parameter differences into more complex models, such as crash impact models.

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