The urinary bladder stores urine and permits proper micturition, both functions that are inherently mechanical. Bladder research to date has been limited to whole-organ testing and simple uniaxial study, both of which are inadequate for comprehensive modeling and rigorous analysis of the mechanical properties of the bladder wall. In this work, we studied the quasi-static and time-dependent properties of the bladder wall to further understand bladder function. To obtain the requisite multiaxial data we utilized biaxial testing techniques, which allow for a more realistic physiological loading state. The goal of the study was to develop a comprehensive understanding of bladder wall biomechanics to provide insight into tissue-level bladder function. This information can be compared against other ongoing and future studies of pathologies to aid in the design of clinical treatments.
The results indicated that bladder tissue 10 days after spinal cord injury was more compliant than normal bladder when referenced to the preconditioned state. However, the preconditioned state itself was different between normal and spinal-cord-injured groups, indicating large rapid changes in structure. There was a fundamental change in material behavior after spinal cord injury that indicates structural rearrangement on a microstructural fiber level. Unlike other soft tissues, there was no difference in mechanical response over three orders of magnitude of loading strain rate, most likely due to the large range of bladder function, including fast emptying and very slow filling. The time-dependent stress relaxation tests indicated that bladder behavior was dependent on stress level, with less relaxation occurring at higher stress levels. This may be because the massive structural rearrangements during normal function cause more collagen to bear load at higher stress levels as protection from over distention.
This study provided the first mechanically rigorous information regarding the tissue properties of the normal bladder wall, including comparisons to a diseased state. This information can be used to understand how differences in structure caused by disease alter the tissue behavior, and hence the biological function, of the urinary bladder.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-04142003-092041 |
| Date | 08 May 2003 |
| Creators | Gloeckner, Dorothy Claire |
| Contributors | Michael B. Chancellor, Michael S. Sacks, George D. Stetten, Sanjeev G. Shroff, William C de Groat |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu:80/ETD/available/etd-04142003-092041/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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