eprintid: 7984
rev_number: 4
userid: 6
dir: disk0/00/00/79/84
datestamp: 2011-11-10 19:46:11
lastmod: 2016-11-15 13:44:07
status_changed: 2011-11-10 19:46:11
type: thesis_degree
metadata_visibility: show
contact_email: cda9@pitt.edu
item_issues_count: 0
eprint_status: archive
creators_name: Agosti, Christopher D.
creators_email: cda9@pitt.edu
creators_id: CDA9
title: VISCOELASTIC CHARACTERIZATION OF RABBIT NUCLEUS PULPOSUS TISSUE IN TORSIONAL CREEP
ispublished: unpub
divisions: sch_eng_mechanical
full_text_status: public
keywords:  creep; degeneration; humidity chamber; hydration; intervertebral disc; mineral oil; nutting; proteoglycan; quasi linear; recovery; rheological; rheology; small animal model; spine; stress relaxation; tissue engineering; yielding; collagen; isochronal; viscoelasticity
abstract: Recently, molecular therapy approaches have been shown to favorably alter the course of intervertebral disc degeneration (IDD) in a rabbit model. Typical experimental outcome measures for the rabbit model of IDD include MRI, x-ray, histology, and gene expression. Biomechanical function is another desirable parameter through which to compare treatments, although this is difficult due to limited availability of data for small animal models. In the current study, nucleus pulposus tissue was taken from the healthy rabbit intervertebral disc and tested in torsional creep to establish a database of healthy tissue behavior for future use in assessing the functional efficacy of molecular therapy treatments of IDD. Nucleus pulposus tissue was excised from the L5-L6 intervertebral disc, mounted between the cone and plate of an AR1000 Rheometer, and various torsional creep experiments were performed. Several creep models were fit to the data and modeling analyses were conducted. Of the models compared, the Andrade creep model provides the most reliable data extrapolation. It appears that the tissue is nonlinearly viscoelastic since it does not adhere to the Boltzmann superposition principle. A nonlinear viscoelastic constitutive model, derived for Andrade creep and used to predict the strain behavior obtained at higher levels of stress, provides consistent prediction results. The application of this model to degenerated rabbit NP tissue is expected to result in altered model parameters - thus providing quantifiable, functional benchmarks of success for molecular therapy approaches to the treatment of IDD.
date: 2006-09-27
date_type: completed
institution: University of Pittsburgh
refereed: TRUE
etdcommittee_type: committee_chair
etdcommittee_type: committee_member
etdcommittee_type: committee_member
etdcommittee_name: Smolinski, Patrick J.
etdcommittee_name: Plazek, Donald J.
etdcommittee_name: Gilbertson, Lars G.
etdcommittee_email: smolinski@engr.pitt.edu
etdcommittee_id: PATSMOL
etd_defense_date: 2006-04-27
etd_approval_date: 2006-09-27
etd_submission_date: 2006-05-31
etd_access_restriction: immediate
etd_patent_pending: FALSE
assigned_doi: doi:10.5195/pitt.etd.2011.7984
thesis_type: thesis
degree: MSME
committee: Patrick J. Smolinski (smolinski@engr.pitt.edu) - Committee Chair
committee: Donald J. Plazek () - Committee Member
committee: Lars G. Gilbertson () - Committee Member
etdurn: etd-05312006-183824
other_id: http://etd.library.pitt.edu/ETD/available/etd-05312006-183824/
other_id: etd-05312006-183824
citation:   Agosti, Christopher D.  (2006) VISCOELASTIC CHARACTERIZATION OF RABBIT NUCLEUS PULPOSUS TISSUE IN TORSIONAL CREEP.  Master's Thesis, University of Pittsburgh.    (Unpublished)  
document_url: http://d-scholarship-dev.library.pitt.edu/7984/1/AgostiCD2006.pdf