Among vertebrates, whole-body movement is centered around the vertebral column. The bony vertebral column primarily consists of trabecular (spongy) bone that adapts in vivo to support mechanical demands respective to region, ontogeny, ecology, and locomotion. Previous work has extensively investigated the formfunction relationships of vertebral trabecular bone in terrestrial mammals, who use limb contact with a substrate as the primary support against gravity. However, we lack data from obligate swimming mammals whose locomotor ecology diverged from their terrestrial counterparts in two major ways: (1) body mass is supported by water’s uplifting buoyant forces and (2) swimmers power movement through dorsoventral loading of the axial body. This study examined vertebral trabecular bone mechanical properties and micoarchitecture from fully aquatic mammals, specifically sirenians (i.e. manatees) and cetaceans (i.e. dolphins and whales). We compression tested bone from several regions of the vertebral column among developmental stages in Florida manatees (Trichechus manatus latirostris) and among 10 cetacean species (Families Delphinidae and Kogiidae) with various swimming modes and diving behaviors. In addition, we microCT scanned a subset of cetacean vertebrae before subjecting them to mechanical tests. We demonstrated that in precocial manatee calves, vertebrae were the strongest and toughest in the posterior vertebral column, which may support rostrocaudal force propagation and increasing bending amplitudes towards the tail tip during undulatory swimming. Among cetaceans, we showed that greatest strength, stiffness, toughness, bone volume fraction, and degree of anisotropy were in rigidtorso shallow-divers, while properties had the smallest values in flexible-torso deep-divers. We propose that animals swimming in shallower waters actively swim more than species that conduct habitual glides during deep descents in the water column, and place comparatively greater loads on their vertebral columns. We found that cetacean bone volume fraction was the best predictor for mechanical properties. Due to the shared non-weight bearing conditions of water and microgravity, we present these data as a contribution to the body of work investigating bone adaptations in mammals that live in weightless conditions throughout life and evolutionary history. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

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Indiana University-Purdue University Indianapolis (IUPUI) / Heritable disorders of phosphate handling are the most common cause of hypophosphatemic rickets in developed countries. Isolated renal phosphate wasting and subsequent low serum phosphate concentrations may result from a number of genetic disorders that include: autosomal dominant hypophosphatemic rickets (ADHR), X-linked hypophosphatemic rickets (XLH), and autosomal recessive hypophosphatemic rickets (ARHR). Fibroblast growth factor-23 (FGF23), identified as the causative gene in ADHR, is produced in bone and plays a central role in kidney phosphate regulation. Increased serum concentrations of FGF23 lead to renal phosphate wasting through down regulation of renal sodium-phosphate co-transporters. However, the molecular mechanisms of FGF23 bioactivity in hormonal phosphate regulation are largely unknown. An experimental focus of this dissertation was to investigate the molecular mechanisms of FGF23-mediated phosphate regulation in the bone-kidney hormonal axis. To this end, the role of Dentin Matrix Protein 1 (DMP1), newly identified as the gene responsible for ARHR, was further defined by the identification of a novel large deletion as well as testing the molecular consequences of DMP1 mutations. FGF23 requires a signaling complex composed of Klotho and an FGFR for bioactivity, however, the location and composition of the signaling complex is unknown. Klotho localizes to the renal distal convoluted tubule, whereas the sodium phosphate co-transporters are expressed within the renal proximal tubules. The molecular mechanisms of FGF23 signaling were investigated by isolating a novel marker of FGF23 bioactivity using array technology, determining the location of initial FGF23 signaling in the kidney, and by identifying a novel mutation in a receptor upstream of FGF23 production. Taken together, these results increase the knowledge of the molecular mechanisms of phosphate homeostasis in relation to FGF23 bioactivity, leading to the identification of potentially novel therapeutic targets. / indefinitely

As part of a medico-legal analysis it is necessary to identify if bone tissue is animal or human in nature. This process is complicated when bone is highly fragmented or burned. Previous research has established the ability to differentiate human from non-human bone histologically, however, further research is necessary to determine if this is still applicable in the case of burned remains. In South Africa, approximately 500 deaths and 15 000 fire related injuries occur annually in Cape Town and such fires ranged between 600°C to 1000°C. The aim of this research was to study the qualitative and quantitative characteristics of femur bone microstructure of human and animal bones exposed to different temperatures and to determine the possibility of distinguishing them. The study consisted of 17 femoral bone samples collected from four different species namely; humans (Homo sapiens), pig (Sus scrofa), wildebeest (Connochaetes gnou) and cow (Bos taurus). Unburned samples were compared to bone samples burned at 600°C, 700°C, 800°C and 900°C in a muffle furnace for 20 minutes. Bone samples were processed into thin sections for histological analysis. During analysis, each bone specimen was divided into four quadrants and two periosteal regions. For histomorphometric analysis, quantitative characteristics were assessed by measuring the area, perimeter, and minimum and maximum diameter of the Haversian system and Haversian canals as well as osteon circularity and osteon density. According to the qualitative results, the main structural bone tissue observed in all quadrants and two periosteal regions of unburned animal bone was primary vascular plexiform bone and irregular Haversian bone. Human bone consisted of dense Haversian bone. Quantitative results indicated a statistically significant difference in most parameters between species within burned as well as unburned samples (p<0.001). Statistically significant differences in quantitative parameters within human and wildebeest bone were noted at different burn temperatures (p<0.001). Overall, the results showed that heat exposure to bones can affect the bones' quantitative and qualitative characteristics but human and non-human bones can still be differentiated. This histological method can be used in forensic fire cases.

A mathematical model which is used to detect bone edges accurately is described in this thesis. This model is derived by assuming the X-ray source to be a square region. It is shown that for an ideal X-ray source (point source), the bone edge lies exactly at the location of maximum first derivative of the imaged object's transmission function. However, for the non-ideal case, it is shown that the bone edge does not lie at the maximum first derivative location. Also, it is shown that an offset can be calculated from the edge parameters. The Marr- Hildreth edge detector is used to detect the initial estimates for edge location. Precise estimates are obtained by using the facet model. The offset is then calculated and applied to these estimates. / Master of Science

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Dissertation (MSD) --Boston University, Goldman School of Dental Medicine, 2012 (Department of Oral Biology). / Includes bibliographic references: leaves 71-77. / Lysyl oxidases constitute a family of enzymes responsible for the formation of crosslinks in collagen and elastin. These enzymes have also been linked to pathological fibrosis. The importance of collagen in the structural and mechanical properties of bone led us to investigate the hypothesis that the absence of one or more of these enzymes could lead to a significant bone phenotype. This phenotype could resemble osteoporosis or diabetic bone disease. In addition, we tried to overexpress lysyl oxidase proenzyme in vitro. The ability to produce enough amounts of lysyl oxidase proenzyme and the ability to process it and activate it could facilitate the development of drugs that control its activity in pathological fibrosis. [TRUNCATED]

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