Modeling the Inflation Response of C57BL/6 Mouse Sclera

2011 ◽  
Author(s):  
Kristin M. Myers ◽  
Thao D. Nguyen
Keyword(s):  
Material Properties ◽  
Soft Tissues ◽  
Ganglion Cells ◽  
The United States ◽  
Small Rodent ◽  
Tissue Samples ◽  
Tissue Microstructure ◽  
Material Parameters ◽  
Meaningful Material

Small rodent models have become increasingly useful to investigate how the mechanical properties of soft tissues may influence disease development. These animal models allow access to aged, diseased, or genetically-altered tissue samples, and through comparisons with wild-type or normal tissue it can be explored how each of these variables influence tissue function. The challenges to deriving meaningful material parameters for these small tissue samples include designing physiologically-relevant mechanical testing protocols and interpreting the experimental load-displacement data in an appropriate constitutive framework to quantify material parameters. This study was motivated by determining the possible role of scleral material properties in the development of glaucomatous damage to the retinal ganglion cells (RGC). Glaucoma is one of the leading causes of blindness in the United States and in the world with an estimate of 60 million people affected by this year [1]. Through exploring mouse models, the overall goal of our work is to determine the role of scleral material properties and scleral tissue microstructure in the pathogenesis of glaucoma.

The Inflation Response of Mouse Sclera: Age Effects on the Mechanical Properties of Scleral Tissue

2010 ◽  
Author(s):  
Kristin M. Myers ◽  
Frances Cone ◽  
Harry Quigley ◽  
Baptiste Coudrillier ◽  
Thao D. Nguyen
Keyword(s):  
Material Properties ◽  
Visual Information ◽  
Vision Loss ◽  
Ganglion Cells ◽  
The United States ◽  
Ocular Tissue ◽  
Mouse Strains ◽  
Retinal Ganglion ◽  
Deformation Response

The mouse model offers an opportunity to investigate how alterations to the connective soft tissue contribute to the development of disease through the study of transgenic and diseased mouse strains. For example, by measuring the deformation response of the eye wall to increases in pressure of these different mouse types, the possible role of ocular tissue material properties in glaucomatous damage can be determined. Glaucoma is one of the leading causes of blindness in the United States and in the world with an estimate of 60 million people affected by this year [1]. It is caused by damage to the retinal ganglion cells (RGC), a type of neuron that transmits visual information to the brain. Despite therapeutic efforts to reduce the rate of vision loss in glaucoma patients, the rate of blindness remains high [2]. There is evidence that elevated intraocular pressure (IOP) is a strong risk factor for the disease [3–5], and it is hypothesized that possible alterations in the time-dependent scleral material properties may play an important role in cumulative RGC death.

Chemical degeneration of intestinal nerves

1990 ◽  
Vol 258 (6) ◽  
pp. G848-G855 ◽  
Author(s):  
C. T. Frantzides ◽  
J. C. Garancis ◽  
B. T. Doumas ◽  
R. E. Condon
Keyword(s):  
Substance P ◽  
Cobalt Chloride ◽  
Ganglion Cells ◽  
Electron Microscopic ◽  
Tissue Samples ◽  
Mucosal Cells ◽  
Cobalt Solution ◽  
Small Intestinal ◽  
Immunohistochemical Studies

In 15 dogs, cobalt chloride solutions were infused close intra-arterially to perfuse a short segment of the jejunum. In an additional four dogs, the jejunum was perfused with the aqueous vehicle (perfusion control). All animals were killed after 1 mo and tissue samples from cobalt-treated and from nonperfused intestine (tissue comparison control) were obtained for electron microscopic and immunohistochemical studies. Segments infused with 0.25 g/dl cobalt solution showed minimal changes; the most striking feature was an increase of vasoactive intestinal polypeptide (VIP)- and substance P-containing neurosecretory granules. Cobalt chloride at higher concentrations (0.75-1.5 g/dl) induced degeneration of ganglion cells and axons in both the myenteric and submucosal plexi. In contrast, the smooth muscle and the mucosal cells of the cobalt-perfused intestine showed no histological abnormalities. Immunohistochemical staining of tissues treated with 0.75-1.5 g/dl cobalt solutions revealed absence of substance P, Met-enkephalin, and VIP immunoreactivity in all section studied; control segments showed the presence of all three peptides. Cobalt chloride in concentrations of 0.75-1.5 g/dl causes degeneration of intestinal intramural nerves and provides an experimental model suitable for studying the role of these nerves in small intestinal function.

scholarly journals Why Are Viscosity and Nonlinearity Bound to Make an Impact in Clinical Elastographic Diagnosis?

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2379 ◽  
Author(s):  
Guillermo Rus ◽  
Inas H. Faris ◽  
Jorge Torres ◽  
Antonio Callejas ◽  
Juan Melchor
Keyword(s):  
Soft Tissues ◽  
Elastic Parameters ◽  
Tissue Microstructure ◽  
Non Invasive ◽  
Recent Developments ◽  
Mechanical Biomarkers ◽  
Nonlinear Elastic

The adoption of multiscale approaches by the biomechanical community has caused a major improvement in quality in the mechanical characterization of soft tissues. The recent developments in elastography techniques are enabling in vivo and non-invasive quantification of tissues’ mechanical properties. Elastic changes in a tissue are associated with a broad spectrum of pathologies, which stems from the tissue microstructure, histology and biochemistry. This knowledge is combined with research evidence to provide a powerful diagnostic range of highly prevalent pathologies, from birth and labor disorders (prematurity, induction failures, etc.), to solid tumors (e.g., prostate, cervix, breast, melanoma) and liver fibrosis, just to name a few. This review aims to elucidate the potential of viscous and nonlinear elastic parameters as conceivable diagnostic mechanical biomarkers. First, by providing an insight into the classic role of soft tissue microstructure in linear elasticity; secondly, by understanding how viscosity and nonlinearity could enhance the current diagnosis in elastography; and finally, by compounding preliminary investigations of those elastography parameters within different technologies. In conclusion, evidence of the diagnostic capability of elastic parameters beyond linear stiffness is gaining momentum as a result of the technological and imaging developments in the field of biomechanics.

The Bulge Inflation Response of Bovine Sclera

2009 ◽  
Author(s):  
Kristin M. Myers ◽  
Thao D. Nguyen
Keyword(s):  
Visual Information ◽  
Vision Loss ◽  
Mechanical Response ◽  
Ganglion Cells ◽  
The United States ◽  
Retinal Ganglion ◽  
Tissue Samples ◽  
Strip Testing ◽  
The Relationship ◽  
The Brain

Glaucoma is one of the leading causes of blindness in the United States and in the world [1]. It is caused by damage to the retinal ganglion cells (RGC), a type of neuron that transmits visual information to the brain. Despite therapeutic efforts to reduce the rate of vision loss in glaucoma patients, the rate of blindness remains high [2]. There is evidence that elevated intraocular pressure (IOP) plays an important role in the damage to RGCs [3–5], but the relationship between the mechanical properties of the connective tissue and how it affects the cellular function is not understood. The load-bearing eye wall consists of the cornea and the sclera. Both tissues are collagen rich structures with preferentially aligned collagen lamellae dictating its mechanical response. Previous studies have shown that the viscoelastic material response of the eye wall differs between normal and glaucoma animal tissues [6]. However, these previous studies relied on strip testing of tissue samples.

scholarly journals Identification of Material Parameters of a Hyper-Elastic Body With Unknown Boundary Conditions

2018 ◽  
Vol 85 (5) ◽  
Author(s):  
M. Hajhashemkhani ◽  
M. R. Hematiyan ◽  
S. Goenezen
Keyword(s):  
Boundary Conditions ◽  
Elastic Material ◽  
Material Properties ◽  
Soft Tissues ◽  
Material Model ◽  
Unknown Boundary ◽  
Material Parameters ◽  
Hyper Elastic ◽  
Unknown Boundary Conditions

Identification of material properties of hyper-elastic materials such as soft tissues of the human body or rubber-like materials has been the subject of many works in recent decades. Boundary conditions generally play an important role in solving an inverse problem for material identification, while their knowledge has been taken for granted. In reality, however, boundary conditions may not be available on parts of the problem domain such as for an engineering part, e.g., a polymer that could be modeled as a hyper-elastic material, mounted on a system or an in vivo soft tissue. In these cases, using hypothetical boundary conditions will yield misleading results. In this paper, an inverse algorithm for the characterization of hyper-elastic material properties is developed, which takes into consideration unknown conditions on a part of the boundary. A cost function based on measured and calculated displacements is defined and is minimized using the Gauss–Newton method. A sensitivity analysis is carried out by employing analytic differentiation and using the finite element method (FEM). The effectiveness of the proposed method is demonstrated through numerical and experimental examples. The novel method is tested with a neo–Hookean and a Mooney–Rivlin hyper-elastic material model. In the experimental example, the material parameters of a silicone based specimen with unknown boundary condition are evaluated. In all the examples, the obtained results are verified and it is observed that the results are satisfactory and reliable.

The Role of Gender and Sensation Seeking in Film Choice

2008 ◽  
Vol 20 (3) ◽  
pp. 97-105 ◽  
Author(s):  
Smita C. Banerjee ◽  
Kathryn Greene ◽  
Marina Krcmar ◽  
Zhanna Bagdasarov ◽  
Dovile Ruginyte
Keyword(s):  
United States ◽  
Undergraduate Students ◽  
Sensation Seeking ◽  
Negative Mood ◽  
Positive Mood ◽  
The United States ◽  
High Arousal ◽  
Subject Design ◽  
Happy Mood

This study demonstrates the significance of individual difference factors, particularly gender and sensation seeking, in predicting media choice (examined through hypothetical descriptions of films that participants anticipated they would view). This study used a 2 (Positive mood/negative mood) × 2 (High arousal/low arousal) within-subject design with 544 undergraduate students recruited from a large northeastern university in the United States. Results showed that happy films and high arousal films were preferred over sad films and low-arousal films, respectively. In terms of gender differences, female viewers reported a greater preference than male viewers for happy-mood films. Also, male viewers reported a greater preference for high-arousal films compared to female viewers, and female viewers reported a greater preference for low-arousal films compared to male viewers. Finally, high sensation seekers reported a preference for high-arousal films. Implications for research design and importance of exploring media characteristics are discussed.

Confronting the Problems of Professional Sports: A Public Policy Response to Franchise Relocation and Stadium Subsidization

2005 ◽  
Vol 1 ◽  
Author(s):  
Taylor F Brinkman
Keyword(s):  
Local Community ◽  
Professional Sports ◽  
The United States ◽  
Direct Result ◽  
Sports Organizations ◽  
Sports Leagues ◽  
Sports Finance ◽  
Sports Venues ◽  
Benefits And Costs

During the past decade, forty-six professional sports venues were constructed in the United States, while only 16 expansion teams were created by the major sports leagues. Nearly two thirds of these newly built stadiums and arenas were funded with public tax revenues, despite substantial evidence showing no positive economic impact of new sports stadium construction on local communities. In reviewing the economic literature, this article investigates the role of professional sports organizations in the construction and public subsidization of new sports venues. Franchise relocation and public stadium subsidization is a direct result of the monopoly power of professional sports leagues, whose franchise owners extract large subsidies from their host communities by threatening to relocate to viable alternative locations. After explaining how the most common methods of stadium subsidization project a disproportionate allocation of the benefits and costs of hosting a professional team to local community interests, this article outlines several considerations for local policymakers who seek to reinvigorate public discussion of equity concerns in professional sports finance.

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