Measurement of In Vivo Biomechanical Changes Attributable to Epithelial Removal in Keratoconus Using a Noncontact Tonometer

Cornea ◽  
2020 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Mohammed Ziaei ◽  
Akilesh Gokul ◽  
Hans Vellara ◽  
Lucy M. Lu ◽  
Dipika V. Patel ◽  
...  
Keyword(s):  
Biomechanical Changes ◽  
Noncontact Tonometer

Abstract 17070: Engineering a Novel Ex Vivo Heart Simulator for Biomechanical Analysis of the Aortomitral Junction

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Matthew H Park ◽  
Annabel Imbrie-moore ◽  
Yuanjia Zhu ◽  
Hanjay Wang ◽  
Michael J Paulsen ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Ex Vivo ◽  
Clinical Care ◽  
Biomechanical Analysis ◽  
Future Experimentation ◽  
3D Printed ◽  
Biomechanical Changes ◽  
Predictive Risk ◽  
Future Work

Introduction: Advances in ex vivo heart simulation have enabled the study of valvular biomechanics, disease pathologies, and repair strategies. However, these simulators test the valves in isolation, which does not fully replicate in vivo physiology. We hypothesize that by engineering a simulator that preserves the aortomitral junction, we can better recreate pathophysiologies such as systolic anterior motion (SAM). Here, we present a new heart simulator that preserves and manipulates the native aortomitral physiology. Methods: Our simulator is comprised of three subsystems: the ventricular chamber, atrial chamber, and aortic chamber (Fig A, B). The heart is excised at the apex to preserve the papillary muscles, and the left ventricle, atrial cuff, and aorta are fixed to their respective chambers via hemostatic suturing to 3D-printed elastomeric rings. The chambers are equipped with pressure and flow sensors, and a linear piston pump generates physiologic pressures and flows. The atrial and aortic chambers are mounted on 5-degree-of-freedom arms. To demonstrate system function, we manipulated the aortomitral angle and measured aortic cardiac output. Results: In our testing, we evaluated two unique configurations of an explanted porcine heart, of which the aortomitral angles spanned the SAM predictive risk threshold of <120° (Fig C, D). From the flow readings, we measured a 36% reduction in aortic cardiac output upon decreasing the aortomitral angle by 25°. Conclusions: This work highlights the design and development of an ex vivo heart simulator capable of modeling native aortomitral physiology. Our results point to a clear direction for future experimentation, particularly evaluating the biomechanical changes of the heart based on the aortomitral angle. Future work will utilize this platform to create new models and repair techniques to ultimately improve clinical care of valvular pathologies.

Assessment of the Association Between In Vivo Corneal Biomechanical Changes After Corneal Cross-linking and Depth of Demarcation Line

2019 ◽  
Vol 35 (3) ◽  
pp. 202-206 ◽  
Author(s):  
Riccardo Vinciguerra ◽  
Argyrios Tzamalis ◽  
Vito Romano ◽  
Esmaeil M. Arbabi ◽  
Mark Batterbury ◽  
...  
Keyword(s):  
Cross Linking ◽  
Demarcation Line ◽  
Biomechanical Changes

Biomechanical Changes after in vivo Enzyme-Induced Corneal Crosslinking in Rabbits

2019 ◽  
Vol 63 (5) ◽  
pp. 501-506 ◽  
Author(s):  
Yuan Wu ◽  
Wenjing Song ◽  
Yun Tang ◽  
Xiaoming Yan
Keyword(s):  
Corneal Crosslinking ◽  
Biomechanical Changes

Comparative in Vivo Analysis of the Role of the Adventitia and the Endothelium on Arterial Mechanical Function: Relevance for Aortic Counterpulsation

2017 ◽  
Vol 40 (6) ◽  
pp. 286-293 ◽  
Author(s):  
Daniel Bia ◽  
Yanina Zócalo ◽  
Sandra Wray ◽  
Edmundo I. Cabrera-Fischer
Keyword(s):  
Heart Failure ◽  
Arterial Diameter ◽  
Iliac Arteries ◽  
Arterial Conduit ◽  
Before And After ◽  
In Vivo Analysis ◽  
Biomechanical Changes ◽  
Biomechanical Parameters

Purpose The comparative effect of the intimal and adventitial layers on arterial biomechanics control, in basal and altered conditions, remains to be elucidated. This study aimed ( 1 ) to characterize the arterial conduit (CF) and buffering (distensibility) function of the iliac arteries in in vivo animals, in which the intimal and adventitial layers were removed; ( 2 ) to determine the effects of intra-aortic ballon pumping (IABP) on simultaneously de-adventitialized (DA) and de-endothelialized (DE) iliac arteries before and after induced heart failure. Methods Pressure and diameter signals were measured in the iliac arteries of sheep (n = 7) in which the adventitial and intima layer were removed. Intra-aortic balloon pump (IABP) assistance was used in a control state and after heart failure induction. Results Both DE and DA determined significant changes in arterial diameter, distensibility and CF. Changes were higher after DA than after DE in terms of distensibility and CF (p<0.05). DA followed by DE (DA + DE) showed significant increases in arterial diameter and CF, accompanied by a decrease in distensibility (p<0.05) with respect to intact arteries. Heart failure induction caused significant hemodynamic changes without modifying the already impaired local biomechanical parameters. Nonsignificant improvements in the biomechanical parameters of DA+ DE iliac arteries were observed during IABP before and after heart failure induction. Conclusions Biomechanical changes caused by DA of iliac arteries were more important than those observed after DE. The DA + DE arteries showed significant differences with respect to intact arteries and with DA or DE arteries. IABP-related effects on arterial mechanics were absent in DA+ DE arteries.

In Vivo Early Corneal Biomechanical Changes After Corneal Cross-linking in Patients With Progressive Keratoconus

2017 ◽  
Vol 33 (12) ◽  
pp. 840-846 ◽  
Author(s):  
Riccardo Vinciguerra ◽  
Vito Romano ◽  
Esmaeil M. Arbabi ◽  
Matthias Brunner ◽  
Colin E. Willoughby ◽  
...  
Keyword(s):  
Cross Linking ◽  
Biomechanical Changes

scholarly journals Biomechanical Changes After In Vivo Collagen Cross-Linking With Rose Bengal–Green Light and Riboflavin-UVA

2017 ◽  
Vol 58 (3) ◽  
pp. 1612 ◽  
Author(s):  
Nandor Bekesi ◽  
Patricia Gallego-Muñoz ◽  
Lucía Ibarés-Frías ◽  
Pablo Perez-Merino ◽  
M. Carmen Martinez-Garcia ◽  
...  
Keyword(s):  
Rose Bengal ◽  
Green Light ◽  
Cross Linking ◽  
Biomechanical Changes ◽  
Collagen Cross Linking

scholarly journals DDR2 controls breast tumor stiffness and metastasis by regulating integrin mediated mechanotransduction in CAFs

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Samantha VH Bayer ◽  
Whitney R Grither ◽  
Audrey Brenot ◽  
Priscilla Y Hwang ◽  
Craig E Barcus ◽  
...  
Keyword(s):  
Tumor Microenvironment ◽  
Lung Metastases ◽  
Tumor Stroma ◽  
Collagen Fibers ◽  
Tumor Aggressiveness ◽  
Biomechanical Changes ◽  
Tumor Stiffness ◽  
Collagen Receptor ◽  
Fiber Organization

Biomechanical changes in the tumor microenvironment influence tumor progression and metastases. Collagen content and fiber organization within the tumor stroma are major contributors to biomechanical changes (e., tumor stiffness) and correlated with tumor aggressiveness and outcome. What signals and in what cells control collagen organization within the tumors, and how, is not fully understood. We show in mouse breast tumors that the action of the collagen receptor DDR2 in CAFs controls tumor stiffness by reorganizing collagen fibers specifically at the tumor-stromal boundary. These changes were associated with lung metastases. The action of DDR2 in mouse and human CAFs, and tumors in vivo, was found to influence mechanotransduction by controlling full collagen-binding integrin activation via Rap1-mediated Talin1 and Kindlin2 recruitment. The action of DDR2 in tumor CAFs is thus critical for remodeling collagen fibers at the tumor-stromal boundary to generate a physically permissive tumor microenvironment for tumor cell invasion and metastases.

scholarly journals Ultrasonic evaluations of Achilles tendon mechanical properties poststroke

2009 ◽  
Vol 106 (3) ◽  
pp. 843-849 ◽  
Author(s):  
Heng Zhao ◽  
Yupeng Ren ◽  
Yi-Ning Wu ◽  
Shu Q. Liu ◽  
Li-Qun Zhang
Keyword(s):  
Achilles Tendon ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Biomechanical Properties ◽  
Block Matching ◽  
Cross Sectional ◽  
Mechanical Hysteresis ◽  
Biomechanical Changes ◽  
Hemiparetic Stroke

Spasticity, contracture, and muscle weakness are commonly observed poststroke in muscles crossing the ankle. However, it is not clear how biomechanical properties of the Achilles tendon change poststroke, which may affect functions of the impaired muscles directly. Biomechanical properties of the Achilles tendon, including the length and cross-sectional area, in the impaired and unimpaired sides of 10 hemiparetic stroke survivors were evaluated using ultrasonography. Elongation of the Achilles tendon during controlled isometric ramp-and-hold and ramping up then down contractions was determined using a block-matching method. Biomechanical changes in stiffness, Young's modulus, and hysteresis of the Achilles tendon poststroke were investigated by comparing the impaired and unimpaired sides of the 10 patients. The impaired side showed increased tendon length (6%; P = 0.04), decreased stiffness (43%; P < 0.001), decreased Young's modulus (38%; P = 0.005), and increased mechanical hysteresis (1.9 times higher; P < 0.001) compared with the unimpaired side, suggesting Achilles tendon adaptations to muscle spasticity, contracture, and/or disuse poststroke. In vivo quantitative characterizations of the tendon biomechanical properties may help us better understand changes of the calf muscle-tendon unit as a whole and facilitate development of more effective treatments.

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