Browsing by Author "Byrd, Kenneth E."

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    GABA and Glutamate Levels in Occlusal Splint-Wearing Males with Possible Bruxism
    (Elsevier B.V., 2015-07) Dharmadhikari, Shalmali; Romito, Laura M.; Dzemidzic, Mario; Dydak, Ulrike; Xu, Jun; Bodkin, Cynthia L.; Manchanda, Shalini; Byrd, Kenneth E.; Department of Oral Biology, IU School of Dentistry
    Objective The inhibitory neurotransmitter γ-aminobutyric acid (GABA) plays an important role in the pathophysiology of anxiety behavioural disorders such as panic disorder and post-traumatic stress disorder and is also implicated in the manifestation of tooth-grinding and clenching behaviours generally known as bruxism. In order to test whether the stress-related behaviours of tooth-grinding and clenching share similar underlying mechanisms involving GABA and other metabolites as do anxiety-related behavioural disorders, we performed a Magnetic Resonance Spectroscopy (MRS) study for accurate, in vivo metabolite quantification in anxiety-related brain regions. Design MRS was performed in the right hippocampus and right thalamus involved in the hypothalamic−pituitary−adrenal axis system, together with a motor planning region (dorsal anterior cingulate cortex/pre-supplementary motor area) and right dorsolateral prefrontal cortex (DLPFC). Eight occlusal splint-wearing men (OCS) with possible tooth-grinding and clenching behaviours and nine male controls (CON) with no such behaviour were studied. Results Repeated-measures ANOVA showed significant Group × Region interaction for GABA+ (p = 0.001) and glutamate (Glu) (p = 0.031). Between-group post hoc ANOVA showed significantly lower levels of GABA+ (p = 0.003) and higher levels of Glu (p = 0.002) in DLPFC of OCS subjects. These GABA+ and Glu group differences remained significant (GABA+, p = 0.049; Glu, p = 0.039) after the inclusion of anxiety as a covariate. Additionally, GABA and Glu levels in the DLPFC of all subjects were negatively related (Pearson's r = −0.75, p = 0.003). Conclusions These findings indicate that the oral behaviours of tooth-grinding and clenching, generally known as bruxism, may be associated with disturbances in brain GABAergic and glutamatergic systems.
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    Morphologic Changes in the Mandibular Condyle of Growing Sprague-Dawley Rats After Electrolytic Lesioning of the Trigeminal Motor Nucleus
    (1994) Hurst, Charles A.; Byrd, Kenneth E.; Roberts, W. Eugene; Garetto, Lawrence P.; Hohlt, William; Burr, David
    Lesioning motoneurons in the brainstem alters biomechanical forces and affects craniofacial growth by producing skeletal asymmetries. The purpose of this study was to examine changes that occur in the mandibular condyle in rats that have had their trigeminal motor nucleus (TMN) lesioned. The following null hypothesis was tested: unilateral electrolytic lesioning of the TMN has no effect on condylar morphology in growing rats. To accomplish this, experimental rats received a small electrolytic lesion in their left side TMN. The controls received a sham lesion that caused TMN stimulation with no electrolytic lesion produced. Seven rats from each group were sacrificed at 28, 56, and 84 days postoperatively. The rats were decapitated and their skulls were dried. Mandibular condyles were harvested from the dry rat skulls. The specimens were embedded and sectioned. The sections were stained with H&E. The following parameters were measured: condyle perimeter, condylar widths at 125 μm increments measured with a grid aligned with the condylar neck, width of the condylar neck, and bone surface area proximal to the condylar neck measurement. Experimental groups were compared with control groups by means of factorial analysis of variance, ANOVA, with the factors being the experimental operation and the time of sacrifice. Findings show significant or near borderline significant F tests for right-left differences and side-by-group interactions for width at 625 μm, 750 μm, 875 μm, and 1000 μm from the top of the condyle; but not at the other widths measured. Right-left difference and side-by-time interaction for shape factor measurement were also shown to be significant. The null hypothesis stating unilateral electrolytic lesioning of the TMN has no effect on condylar morphology in growing rats was therefore rejected. The failure to reach significance in some parameters may have been due to the small number of specimens. Due to the fragile nature of the dried specimens, group numbers ranged from seven to four condyle pairs per group. In conclusion, lesions to the TMN of growing rats affect the morphology of the mandibular condyle in the medial-lateral plane. Alterations in morphology during growth after lesioning the TMN were likely caused by changes in the neuromuscular activity of masticatory muscles and their biomechanical effects on bone. Data in this study suggest that it is valuable to view mandibular condyles from a frontal view (i.e., frontal tomography) when altered condylar morphology in human patients is suspected.
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    A New Look at Old Abe’s Color Guard
    (Coddington, 2019) Phillips, Tyler; Zou, Xukai; Byrd, Kenneth E.; Computer and Information Science, School of Science
    Many images of the American Civil War exist today and allow us to gain insight into the lives’ of those involved in the conflict. Unfortunately, these images also pose questions as many of the soldiers they depict are unidentified or identified with unknown reliability. One such image is that of the Wisconsin Infantry Color Guard and their bald eagle mascot “Old Abe.” One of the men in the color guard has been identified as George W. Riley due to an inscription on the back of the image. We perform state-of-art biometric-facial analysis of this soldier and several candidate identities. Through this biometric analysis and corroborating historical documents, we present compelling evidence that this soldier is not George W. Riley, but is more likely Walter J. Quick.