Apparatus to Determine the Macroscopic and Microscopic Biaxial Swelling Response of the Annulus Fibrosus

2002 ◽  
Author(s):  
Paul Hulme ◽  
Sabina Bruehlmann ◽  
Neil A. Duncan
Keyword(s):  
Annulus Fibrosus ◽  
Biaxial Loading ◽  
Mechanical Response ◽  
Swelling Behaviour ◽  
Vertebral Bodies ◽  
And Control ◽  
Bearing Structure ◽  
Outer Annulus Fibrosus

The intervertebral disc (IVD) is a “hydrostatic load-bearing structure” [1], found between the vertebral bodies of the spine. The IVD is composed of the inner and outer annulus fibrosus and a gelatinous center, the nucleus pulposus. Fluid is the largest component of the IVD. Swelling affects the macroscopic mechanical response of the tissue, as well as the microscopic nutrient and solute transport to the cells of the IVD. Previous studies describing the macroscopic swelling behaviour of the annulus fibrosus have been uniaxial in nature [2,3]. However, the behaviour of the annulus is markedly affected by its geometry [3]. By examining a biaxial section of annulus fibrosus with a portion of the bone attachment present, the structure of the annular test section will be maintained and by inference so should its function [4]. Therefore, the objective of this study was to develop an apparatus to investigate simultaneously both the macroscopic and microscopic swelling behaviour of the annulus fibrosus subjected to realistic biaxial loading. The biaxial loading device should maintain the annulus fibrosus in vivo geometry and environment, monitor stress and control tissue strain, while positioning the tissue in a manner that allows for in situ visualization of the cells.

In situ intercellular mechanics of the bovine outer annulus fibrosus subjected to biaxial strains

2004 ◽  
Vol 37 (2) ◽  
pp. 223-231 ◽  
Author(s):  
Sabina B. Bruehlmann ◽  
Paul A. Hulme ◽  
Neil A. Duncan
Keyword(s):  
Annulus Fibrosus ◽  
Outer Annulus ◽  
Outer Annulus Fibrosus

In situmonitoring of X-ray strain pole figures of a biaxially deformed ultra-thin film on a flexible substrate

2014 ◽  
Vol 47 (1) ◽  
pp. 181-187 ◽  
Author(s):  
G. Geandier ◽  
D. Faurie ◽  
P.-O. Renault ◽  
D. Thiaudière ◽  
E. Le Bourhis
Keyword(s):  
Thin Film ◽  
Biaxial Loading ◽  
Mechanical Response ◽  
Flexible Substrate ◽  
X Ray ◽  
Area Detector ◽  
Pole Figures ◽  
Insight Into ◽  
Ultra Thin Film

X-ray strain pole figures (SPFs) have been capturedin situduring biaxial deformation of a gold ultra-thin film (thickness = 40 nm) deposited on a polymer substrate. An area detector was used to extract one line in the reciprocal space while the strained sample was rotated azimuthally step by step to produce the SPF. Such SPFs have been obtained for a textured anisotropic ultra-thin film under controlled non-equibiaxial loading using the SOLEIL synchrotron DIFFABS tensile device. The experimental setup allows the pole figure measurements of {111} and {200} reflections to be performed simultaneously. Interestingly, those two crystallographic directions are related to the two-extreme elastic mechanical behaviour. The full directional lattice strain dependence (SPF) is obtained within 15 min and can be monitored step by step upon loading. This procedure gives an insight into ultra-thin film mechanical response under complex biaxial loading.

Biaxial Mechanical Testing of Single Annulus Fibrosus Layers

2010 ◽  
Author(s):  
J. P. Rys ◽  
A. M. Ellingson ◽  
D. J. Nuckley ◽  
V. H. Barocas
Keyword(s):  
Intervertebral Disc ◽  
Annulus Fibrosus ◽  
Spinal Nerve ◽  
Older Individuals ◽  
Physical Trauma ◽  
Age Related ◽  
Biaxial Mechanical Testing ◽  
Partial Displacement ◽  
Outer Annulus Fibrosus

The intervertebral disc (IVD), consisting of the inner nucleus pulposus and the outer annulus fibrosus, is subjected to multiaxial stress in vivo. The disc undergoes degenerative changes that account for impairment and disability in middle-aged and older individuals.4 In addition to age-related degeneration, the intervertebral disc is subject to the development of lesions due to partial displacement or rupture of the annulus fibrosus. Such occurrences, typically resulting from physical trauma, can yield disabling effects from impingement on spinal nerve structures. A greater understanding of the IVD and how it functions mechanically is crucial in prevention and repair of debilitating spinal disorders.

Assessment of airway response distribution and paradoxical airway dilation in mice during methacholine challenge

2017 ◽  
Vol 122 (3) ◽  
pp. 503-510 ◽  
Author(s):  
S. Dubsky ◽  
G. R. Zosky ◽  
K. Perks ◽  
C. R. Samarage ◽  
Y. Henon ◽  
...  
Keyword(s):  
Dynamic Imaging ◽  
Lung Mechanics ◽  
Imaging Method ◽  
Response Distribution ◽  
Interconnected System ◽  
Airway Response ◽  
Airway Responses ◽  
And Control

Detailed information on the distribution of airway diameters during bronchoconstriction in situ is required to understand the regional response of the lungs. Imaging studies using computed tomography (CT) have previously measured airway diameters and changes in response to bronchoconstricting agents, but the manual measurements used have severely limited the number of airways measured per subject. Hence, the detailed distribution and heterogeneity of airway responses are unknown. We have developed and applied dynamic imaging and advanced image-processing methods to quantify and compare hundreds of airways in vivo. The method, based on CT, was applied to house dust-mite-sensitized and control mice during intravenous methacholine (MCh) infusion. Airway diameters were measured pre- and post-MCh challenge, and the results compared demonstrate the distribution of airway response throughout the lungs during mechanical ventilation. Forced oscillation testing was used to measure the global response in lung mechanics. We found marked heterogeneity in the response, with paradoxical dilation of airways present at all airway sizes. The probability of paradoxical dilation decreased with decreasing baseline airway diameter and was not affected by pre-existing inflammation. The results confirm the importance of considering the lung as an entire interconnected system rather than a collection of independent units. It is hoped that the response distribution measurements can help to elucidate the mechanisms that lead to heterogeneous airway response in vivo. NEW & NOTEWORTHY Information on the distribution of airway diameters during bronchoconstriction in situ is critical for understanding the regional response of the lungs. We have developed an imaging method to quantify and compare the size of hundreds of airways in vivo during bronchoconstriction in mice. The results demonstrate large heterogeneity with both constriction and paradoxical dilation of airways, confirming the importance of considering the lung as an interconnected system rather than a collection of independent units.

The Development of an In Situ Assay for bFGF Release

1993 ◽  
Vol 331 ◽  
Author(s):  
S. K. Hobbs ◽  
L. M. Periolat ◽  
L. G. Cima ◽  
M. Nugent ◽  
M. Leunig ◽  
...  
Keyword(s):  
In Vivo Studies ◽  
Dorsal Skinfold Chamber ◽  
Control Growth ◽  
Vessel Growth ◽  
And Control ◽  
Tissue Reactivity ◽  
In Situ Assay

AbstractThere is a need for an in situ assay to quantify tissue reactivity to sustained release of bFGF to better understand and control growth factor-induced angiogenesis. To this end we have adapted the alginate/heparin-sepharose release system for use in the mouse dorsal skinfold chamber. A mathematical model was used to predict the time dependence of bFGF release as a function of bFGF loading, heparin concentration, and device geometry. The model predictions agreed well with previously reported in vitro data. In vivo studies to correlate blood vessel growth as a function of release rate are in progress.

Dynamic mechanical response of brain tissue in indentation in vivo, in situ and in vitro

2011 ◽  
Vol 7 (12) ◽  
pp. 4090-4101 ◽  
Author(s):  
Thibault P. Prevost ◽  
Guang Jin ◽  
Marc A. de Moya ◽  
Hasan B. Alam ◽  
Subra Suresh ◽  
...  
Keyword(s):  
Brain Tissue ◽  
Mechanical Response ◽  
Dynamic Mechanical

scholarly journals Seeing the Light: The Use of Zebrafish for Optogenetic Studies of the Heart

2021 ◽  
Vol 12 ◽  
Author(s):  
Jonathan S. Baillie ◽  
Matthew R. Stoyek ◽  
T. Alexander Quinn
Keyword(s):  
Experimental Model ◽  
Optical Measurement ◽  
Cardiac Activity ◽  
Experimental Models ◽  
Spatially Resolved ◽  
And Control ◽  
Spatiotemporal Control ◽  
Insight Into

Optogenetics, involving the optical measurement and manipulation of cellular activity with genetically encoded light-sensitive proteins (“reporters” and “actuators”), is a powerful experimental technique for probing (patho-)physiological function. Originally developed as a tool for neuroscience, it has now been utilized in cardiac research for over a decade, providing novel insight into the electrophysiology of the healthy and diseased heart. Among the pioneering cardiac applications of optogenetic actuators were studies in zebrafish, which first demonstrated their use for precise spatiotemporal control of cardiac activity. Zebrafish were also adopted early as an experimental model for the use of optogenetic reporters, including genetically encoded voltage- and calcium-sensitive indicators. Beyond optogenetic studies, zebrafish are becoming an increasingly important tool for cardiac research, as they combine many of the advantages of integrative and reduced experimental models. The zebrafish has striking genetic and functional cardiac similarities to that of mammals, its genome is fully sequenced and can be modified using standard techniques, it has been used to recapitulate a variety of cardiac diseases, and it allows for high-throughput investigations. For optogenetic studies, zebrafish provide additional advantages, as the whole zebrafish heart can be visualized and interrogated in vivo in the transparent, externally developing embryo, and the relatively small adult heart allows for in situ cell-specific observation and control not possible in mammals. With the advent of increasingly sophisticated fluorescence imaging approaches and methods for spatially-resolved light stimulation in the heart, the zebrafish represents an experimental model with unrealized potential for cardiac optogenetic studies. In this review we summarize the use of zebrafish for optogenetic investigations in the heart, highlighting their specific advantages and limitations, and their potential for future cardiac research.

Augmented bidirectional HCO3 transport by rat distal tubules in chronic alkalosis

1991 ◽  
Vol 261 (2) ◽  
pp. F308-F317 ◽  
Author(s):  
D. E. Wesson ◽  
G. M. Dolson
Keyword(s):  
Metabolic Alkalosis ◽  
Distal Tubule ◽  
Free Flow ◽  
Proton Secretion ◽  
Nephron Segment ◽  
Distal Tubules ◽  
And Control

Free-flow micropuncture studies show both augmented net HCO3 reabsorption in the distal tubule of rats with chronic metabolic alkalosis and higher HCO3 delivery to this nephron segment. The present studies in rats used in vivo microperfusion of surface distal tubules to investigate whether the augmented net reabsorption 1) was due to decreased HCO3 secretion and/or to increased proton secretion or 2) depended on the higher HCO3 delivery to the distal tubule. Artificial perfusates were designed to simulate in situ deliveries of HCO3 to the distal tubules of both alkalotic and control animals and to represent extremes of in situ Cl deliveries. Rather than being decreased, both measured and calculated HCO3 secretion were higher in the alkalotic animals for each perfusate used. Similarly, calculated proton secretion (difference between net HCO3 reabsorption and calculated HCO3 secretion) was higher for the alkalotic animals using each HCO3-containing perfusate. Augmented net HCO3 reabsorption by alkalotic animals was more clearly demonstrated using higher HCO3 deliveries and Cl-free perfusates. These studies demonstrate that both the reabsorptive and secretory components of net HCO3 transport are increased in the distal tubule of animals with chronic metabolic alkalosis.

scholarly journals Evidence of a tunable biological spring: elastic energy storage in aponeuroses varies with transverse strain in vivo

2019 ◽  
Vol 286 (1900) ◽  
pp. 20182764 ◽  
Author(s):  
Christopher J. Arellano ◽  
Nicolai Konow ◽  
Nicholas J. Gidmark ◽  
Thomas J. Roberts
Keyword(s):  
Energy Storage ◽  
Mechanical Behaviour ◽  
Elastic Energy ◽  
Biaxial Loading ◽  
Longitudinal Direction ◽  
General Assumption ◽  
Transverse Strain ◽  
Longitudinal Stiffness

Tendinous structures are generally thought of as biological springs that operate with a fixed stiffness, yet recent observations on the mechanical behaviour of aponeuroses (broad, sheet-like tendons) have challenged this general assumption. During in situ contractions, aponeuroses undergo changes in both length and width and changes in aponeuroses width can drive changes in longitudinal stiffness. Here, we explore if changes in aponeuroses width can modulate elastic energy (EE) storage in the longitudinal direction. We tested this idea in vivo by quantifying muscle and aponeuroses mechanical behaviour in the turkey lateral gastrocnemius during landing and jumping, activities that require rapid rates of energy dissipation and generation, respectively. We discovered that when aponeurosis width increased (as opposed to decreased), apparent longitudinal stiffness was 34% higher and the capacity of aponeuroses to store EE when stretched in the longitudinal direction was 15% lower. These data reveal that biaxial loading of aponeuroses allows for variation in tendon stiffness and energy storage for different locomotor behaviours.

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