Browsing by Author "Tomaschke, Andrew A."

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    Assessing cortical bone porosity with MRI in an animal model of chronic kidney disease
    (Elsevier, 2023) Newman, Christopher L.; Surowiec, Rachel K.; Swallow, Elizabeth A.; Metzger, Corinne E.; Kim, Jieun; Tomaschke, Andrew A.; Chen, Neal X.; Allen, Matthew R.; Wallace, Joseph M.; Moe, Sharon M.; Wu, Yu-Chien; Niziolek, Paul J.; Radiology and Imaging Sciences, School of Medicine
    Chronic kidney disease (CKD) is characterized by secondary hyperparathyroidism and an increased risk of hip fractures predominantly related to cortical porosity. Unfortunately, bone mineral density measurements and high-resolution peripheral computed tomography (HR-pQCT) imaging have shortcomings that limit their utility in these patients. Ultrashort echo time magnetic resonance imaging (UTE-MRI) has the potential to overcome these limitations by providing an alternative assessment of cortical porosity. The goal of the current study was to determine if UTE-MRI could detect changes in porosity in an established rat model of CKD. Cy/+ rats (n = 11), an established animal model of CKD-MBD, and their normal littermates (n = 12) were imaged using microcomputed tomography (microCT) and UTE-MRI at 30 and 35 weeks of age (which approximates late-stage kidney disease in humans). Images were obtained at the distal tibia and the proximal femur. Cortical porosity was assessed using the percent porosity (Pore%) calculated from microCT imaging and the porosity index (PI) calculated from UTE-MRI. Correlations between Pore% and PI were also calculated. Cy/+ rats had higher Pore% than normal rats at both skeletal sites at 35 weeks (tibia = 7.13 % +/- 5.59 % vs. 0.51 % +/- 0.09 %, femur = 19.99 % +/- 7.72 % vs. 2.72 % +/- 0.32 %). They also had greater PI at the distal tibia at 30 weeks of age (0.47 +/- 0.06 vs. 0.40 +/- 0.08). However, Pore% and PI were only correlated in the proximal femur at 35 weeks of age (ρ = 0.929, Spearman). These microCT results are consistent with prior studies in this animal model utilizing microCT imaging. The UTE-MRI results were inconsistent, resulting in variable correlations with microCT imaging, which may be related to suboptimal bound and pore water discrimination at higher magnetic field strengths. Nevertheless, UTE-MRI may still provide an additional clinical tool to assess fracture risk without using ionizing radiation in CKD patients.
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    Ribosylation-induced increase in advanced glycation end products has limited impacts on mechanical properties in human cortical bone
    (Elsevier, 2025-04-02) Gallagher, Katelynn R.; White, Olivia N.; Tomaschke, Andrew A.; Segvich, Dyann M.; Wallace, Joseph M.; Biomedical Engineering, Purdue School of Engineering and Technology
    Diabetes affects over 38 million individuals in the U.S. and is associated with a heightened risk of fractures despite normal or elevated bone mineral density (BMD). This increased fracture susceptibility may be linked to the accumulation of advanced glycation end products (AGEs), which are theorized to compromise bone quality by stiffening the collagen network, leading to tissue embrittlement. In this study, the mechanical effects of AGE accumulation in human cortical bone were evaluated in vitro. Bone beams, derived from a human femur, were incubated in a ribose solution to induce AGE accumulation, while control beams were incubated in a control solution. Dynamic Mechanical Analysis (DMA) and three-point bending tests were conducted to assess the mechanical properties of the bone beams. Fluorescent AGE analysis was performed to quantify and compare AGE levels between the groups. The study found no significant differences in mechanical properties between the control and ribose-treated groups, despite a significant elevation in normalized AGE content in the ribose group. These results suggest that AGE accumulation may have a weaker impact on the mechanical properties of human bone than previously hypothesized. However, this study emphasizes the need for further research to explore the relationship between AGE accumulation and bone quality. Understanding this relationship is crucial for developing strategies to reduce fracture risk in populations with high AGE levels, such as diabetic and elderly individuals.