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Mutations of the Shank3 gene have consistently been identified as a risk factor for Autism Spectrum Disorder, and are associated with neurological abnormalities indicative of neural connectivity issues. This project aimed to elucidate the functions of Shank3 protein in the growth cone during neural development. It was hypothesised that in dorsal root ganglia growth cones, Shank would colocalise with Homer1b/c (a protein that regulates intracellular calcium responses to BDNF), that siRNA-mediated knockdown of Shank3 protein would reduce Shank expression, and that Shank3 knockdown would abolish growth cone turning responses to BDNF. Shank and Homer appeared to colocalise in the growth cone. However, Shank3 knockdown did not decrease protein expression, and cell culture issues required that turning assays be terminated. As such, this research infers a role of Shank protein in peripheral nervous development but is unable to clarify the specific implications of this for axon pathfinding. Directions for future research include addressing cell culture issues, and repeating knockdown and turning experiments on hippocampal cells known to express Shank3 in the growth cone.

Biofilm formation is important in the pathogenesis of many bacterial infections of both humans and animals. Coagulase-negative staphylococci (CNS) are significant biofilm-producing pathogens found in human foreign-body infections and ruminant mastitis. We have previously shown differences in biofilm production by representatives of various genotypes of Staphylococcus aureus causing bovine mastitis. We further demonstrated that 2-aminoimidazole compounds have anti-biofilm and antibacterial potentiation properties when tested in vitro using these isolates. The CNS are the bacteria most commonly isolated from goat milk, and they can be important pathogens in the goat mammary gland. Our purpose was to evaluate the biofilm-forming potential of representatives of genotypes of the most common CNS we found in goat mastitis. We hypothesized differences in biofilm-producing potential among goat CNS isolates and that biofilm formation may reflect pathogenic potential. Using the most prolific biofilm-forming CNS isolate, we hypothesized that 2-aminoimidazole compounds would inhibit biofilm production and potentiate antibacterial activity., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2018

© 2015 ISS Objective: To implement high-resolution morphologic and quantitative magnetic resonance imaging (MRI) of the temporomandibular joint (TMJ) using ultrashort time-to-echo (UTE) techniques in cadavers and volunteers. Methods: This study was approved by the institutional review board. TMJs of cadavers and volunteers were imaged on a 3-T MR system. High-resolution morphologic and quantitative sequences using conventional and UTE techniques were performed in cadaveric TMJs. Morphologic and UTE quantitative sequences were performed in asymptomatic and symptomatic volunteers. Results: Morphologic evaluation demonstrated the TMJ structures in open- and closed-mouth position. UTE techniques facilitated the visualization of the disc and fibrocartilage. Quantitative UTE MRI was successfully performed ex vivo and in vivo, reflecting the degree of degeneration. There was a difference in the mean UTE T2* values between asymptomatic and symptomatic volunteers. Conclusions: MRI evaluation of the TMJ using UTE techniques allows characterization of the internal structure and quantification of the MR properties of the disc. Quantitative UTE MRI can be performed in vivo with short scan times.

© 2015 John Wiley & Sons, Ltd. Magnetization transfer (MT) imaging is one way to indirectly assess pools of protons with fast transverse relaxation. However, conventional MT imaging sequences are not applicable to short T2tissues such as cortical bone. Ultrashort echo time (UTE) sequences with TEvalues as low as 8μs can detect signals from different water components in cortical bone. In this study we aim to evaluate two-dimensional UTE-MT imaging of cortical bone and its application in assessing cortical bone porosity as measured by micro-computed tomography (μCT) and biomechanical properties. In total, 38 human cadaveric distal femur and proximal tibia bones were sectioned to produce 122 rectangular pieces of cortical bone for quantitative UTE-MT MR imaging, μCT, and biomechanical testing. Off-resonance saturation ratios (OSRs) with a series of MT pulse frequency offsets (Δf) were calculated and compared with porosity assessed with μCT, as well as elastic (modulus, yield stress, and strain) and failure (ultimate stress, failure strain, and energy) properties, using Pearson correlation and linear regression. A moderately strong negative correlation was observed between OSR and μCT porosity (R2=0.46-0.51), while a moderate positive correlation was observed between OSR and yield stress (R2=0.25-0.30) and failure stress (R2=0.31-0.35), and a weak positive correlation (R2=0.09-0.12) between OSR and Young's modulus at all off-resonance saturation frequencies. OSR determined with the UTE-MT sequence provides quantitative information on cortical bone and is sensitive to μCT porosity and biomechanical function.

© 2015 John Wiley & Sons, Ltd. Magnetization transfer (MT) imaging is one way to indirectly assess pools of protons with fast transverse relaxation. However, conventional MT imaging sequences are not applicable to short T2 tissues such as cortical bone. Ultrashort echo time (UTE) sequences with TE values as low as 8μs can detect signals from different water components in cortical bone. In this study we aim to evaluate two-dimensional UTE-MT imaging of cortical bone and its application in assessing cortical bone porosity as measured by micro-computed tomography (μCT) and biomechanical properties. In total, 38 human cadaveric distal femur and proximal tibia bones were sectioned to produce 122 rectangular pieces of cortical bone for quantitative UTE-MT MR imaging, μCT, and biomechanical testing. Off-resonance saturation ratios (OSRs) with a series of MT pulse frequency offsets (Δf) were calculated and compared with porosity assessed with μCT, as well as elastic (modulus, yield stress, and strain) and failure (ultimate stress, failure strain, and energy) properties, using Pearson correlation and linear regression. A moderately strong negative correlation was observed between OSR and μCT porosity (R2=0.46-0.51), while a moderate positive correlation was observed between OSR and yield stress (R2=0.25-0.30) and failure stress (R2=0.31-0.35), and a weak positive correlation (R2=0.09-0.12) between OSR and Young's modulus at all off-resonance saturation frequencies. OSR determined with the UTE-MT sequence provides quantitative information on cortical bone and is sensitive to μCT porosity and biomechanical function.