Feller, David Daniel
(2013)
The Effects Of Post-Natal Hyperthyroidism on Coronal Suture Fusion and Calvarial Growth in Rabbits with Familial, Delayed-Onset Synostosis: Testing a Gene/Environmental Causal Mechanism of Variable Phenotypic Expression of Craniosynostosis.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Early fusion of craniosynostosis may occur prior to birth or afterwards during cranial vault growth. The cause of craniosynostosis may be due to genetic maturations and/or environmental influences. Many reports show environmental influences increasing the penetrance or expression of craniosynostosis. The purpose of this study is to identify the environmental influences of post-natal administration of tri-iodothyronine (T3) in rabbits that demonstrate familial delayed onset craniosynostosis, and identify a possible gene/environment interaction.
A total of 65 New Zealand white rabbits (Oryctolagus cuniculus) were used. Forty one (41) rabbits with delayed onset craniosynostosis were obtained, as well as 24 in-colony normal rabbits from a similar colony, but who did not display phenotypic expression of craniosynostosis. Both phenotypic groups were divided into 3 treatments groups: post-natal injections of tri-iodothyronine (T3), vehicle sham, or control no-treatment group. A 2x3x3 (phenotype x treatment x age) design was used. Amalgam markers were placed around frontonasal, coronal and anterior lambdoid suture. Lateral and dorsoventral cephalograms were taken at 10, 25 and 42 days. Lateral cephalograms were traced, 13 anatomic landmarks identified, and both linear and angular measurements were made. Correlation between treatment group and coronal suture marker measurement was made.
Results showed statistically increased blood T3 levels (F = 5.96, p<0.005) and decreased blood T4 levels (F = 41.07; p<0.000) in T3 treated groups. Coronal suture marker separation decreased in treated rabbits but was not significant (F=2.07; p NS). Mean changes in body weight were significant in T3 treated groups (F=6.91; p<0.002). Mean changes in total craniofacial length, cranial vault and length, and cranial base angle were not significant. Mean changes in cranial vault shape index were significant (F=5.837; p<0.006). Mean changes in palatal angle were significant for delayed on-set rabbits as well as T3 treated groups (F=4.535; p<0.05; and F=3.333; p<0.05).
In conclusion, the effect of T3 on cranial development showed changes in cranial vault shape index and palatal plane angle. Decreased coronal suture marker separation was observed in T3 treated rabbits but not statistically significant. No gene/environment interaction was observed in this study and other factors affecting variable phenotypic expression should be explored.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
8 July 2013 |
| Date Type: |
Publication |
| Defense Date: |
7 June 2013 |
| Approval Date: |
8 July 2013 |
| Submission Date: |
10 June 2013 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
81 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
School of Dental Medicine > Dental Science |
| Degree: |
MDS - Master of Dental Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Craniosynostosis, thyroxine, tri-iodothyronine, coronal, suture, synostosis, fusion, delayed on-set, gene/environment, rabbit, amalgam, growth, calvarial, thyroid |
| Date Deposited: |
08 Jul 2013 14:46 |
| Last Modified: |
15 Nov 2016 14:13 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/18929 |
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