Browsing by Subject "Bone and Bones"
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Item Dietary protein in bone health: friend and foe(2006-02-16) Sakhaee, KhashayarItem Evaluating Bone by Ultrasound(2008-05-13) Liu, Peiying; Antich, Peter P.Bone fractures associated with osteoporosis, a major bone disease characterized by low density and high fracture risk, are common causes of disability and large medical care expenses around the world. Considering its low cost, high portability, and non-ionizing nature, non-invasive ultrasound techniques have been investigated as tools for evaluating bone quality and biomechanical competence. Quantitative ultrasound has been used clinically as a surrogate for the current gold standard measure in osteoporosis diagnosis - Bone Mineral Densitometry (BMD), which unfortunately utilizes ionizing radiation. This study proposes the application of a reflection ultrasound method to evaluate non-BMD properties of cancellous bone, including porosity and the microstructure of the trabecular network, all of which are directly related to bone morphological changes caused by osteoporosis and could result in better predictions of fracture risk. Computer simulations and phantom studies were adopted to guide the measurement of bone properties. In the computer simulations, the cellular model and the wire model of cancellous bone predict the backscattering dependence on porosity from two different perspectives, but reach the same result. This leads to the first conclusion that reflection ultrasound is not sensitive to the shape of a scatterer of wavelength size but to the spacing between scatterers. The in vitro cancellous bone study demonstrated that the average porosity is correlated with the density, while the local porosity depends upon the heterogeneity of the cancellous bone. The average porosity of cancellous bone can be directly determined from ultrasound signals reflected from the bone. Results of the ex vivo and in vivo short bone studies in patella are in agreement with that of Ultrasound Critical-angle Reflectometry (UCR). Thus, the second conclusion of this dissertation is that reflection ultrasound can be an effective tool for assessing bone properties in vivo. During the short bone-mimicking phantom study, the first critical angle detected by UCR was shown to correspond to the solid ultrasound velocity and is independent of porosity, but its amplitude is strongly related to porosity; the second critical angle, corresponding to bulk ultrasound velocity, is strongly related to porosity, but the correlation between its amplitude and the porosity is weak.Item [News](1989-01-12) Rutherford, SusanItem [News](1988-07-05) Rutherford, SusanItem Postpartum period: an opportunity to improve maternal metabolic health(2015-08-28) Ramos-Roman, Maria A.Item Vanishing Act: Lymphatic Vessels and Disappearing Bones(December 2021) Monroy, Marco Antonio; Jewell, Jenna L.; Dellinger, Michael T.; Cleaver, Ondine; Brekken, Rolf A.Generalized lymphatic anomaly (GLA) and Gorham-Stout disease (GSD) are related diseases of the lymphatic system. Patients with GLA or GSD develop ectopic lymphatic vessels in bone and gradually lose bone. Despite growing interest in the development of tissue-specific lymphatics, the cellular origin of bone lymphatic endothelial cells (bLECs) is not known, and the development of bone lymphatics has not been fully characterized. In this dissertation, I review the latest advances in research on the development of the lymphatic system and human lymphatic diseases. I also present my work on the development of bone lymphatics in mouse models of GLA and GSD. I show by lineage-tracing that bLECs arise from pre-existing Prox1-positive LECs. I demonstrate that bone lymphatics develop in a stepwise manner, where regional lymphatics grow, breach the periosteum, and then invade bone. I also show that osteoclasts are closely associated with invading lymphatics and that lymphatic invasion of bone is impaired in mice that lack osteoclasts. Additionally, I demonstrate that rapamycin suppresses the formation of bone lymphatics in mouse models of GLA and GSD. These findings shed light on the development of bone lymphatics, a process that has puzzled investigators since Gorham and Stout published their landmark paper over 60 years ago. They also show that an emerging treatment for GLA and GSD patients can inhibit lymphatic invasion of bone.