This thesis concentrates on discovering the best consolidant or consolidants for stabilizing a Columbian mammoth’s sub-fossilized mandibles, a distal femur, an ulna, a radius, and a tooth. It was recovered from a wet, sandy gravel pit owned by the Vernor Family located in Clute, Texas. Based on thermoluminescence dating, the mammoth dates to around 66,000 years ago. The bones are fragile and unstable. They retain a minute amount of organic material (collagen) and hydroxyapatite, but not enough to retain any structural support. Experiments and analyses were conducted on various bone samples to compare each of the following consolidants’ properties. The consolidants examined were silicone oil, polyvinyl acetate (PVA) with viscosity of 25, Acryloid B-72, Butvar 98, Starbond EM-02, methyltrimethoxysilane (MTMS), Paleo-bond, and Rhoplex (Primal) WS24. Stability, strength, and appearance were evaluated by measurable observations. The Scanning Electron Microscope (SEM) and the Environmental Scanning Electron Microscope (ESEM) at the Microscopy and Imaging Center at Texas A&M University were used to map penetration of these consolidants. SEM was utilized for both imaging and energy-dispersive x-ray spectroscopy (EDS) to examine the presence and absence of certain elements. ESEM was used to view consolidants at the microscopic level to further examine the bonding between the consolidant and the bone’s cellular structure. By examining and testing all the consolidants, methyltrimethoxysilane (MTMS) was chosen to stabilize the ulna, radius, left and right mandibles, distal femur, and tooth. This research opened new avenues to different methods in preserving sub-fossilized bone and broadens our understanding of bone conservation.

NASA goals include long-term International Space Station (ISS) missions and the ambitious objective of eventually sending astronauts to Mars. Unfortunately, exposure to unloading due to microgravity during spaceflight has been shown to cause detrimental health effects on bone. Therefore, NASA is seeking a ground-based animal model to study the long-term effects of unloading on bone in order to better insure the health and mission capability of astronauts. The hindlimb unloaded (HU) rat model was used to study the effects of multiple unloading exposures and aging on bone properties. Six month old, adult, male Sprague-Dawley rats were separated into the following groups: baseline (BL, sacrificed when received at 6 months age), aging cage control (AC, normal weight-bearing cage activity), 1HU7 (unloaded for 1 month starting at 7 months of age and allowed to recover for 3 months), 1HU10 (normal cage activity until 10 months of age, unloaded for 1 month, recovered for 2 months), and 2HU10 (unloaded for 1 month at 7 months of age, allowed to recover for 2 months, unloaded again for 1 month at 10 months of age, followed by 2 months of recovery). Every 28 days a subset of animals (n=15) were euthanized and both femurs were excised. A peripheral quantitative computed tomography (pQCT) scanner was used to collect densitometric and geometric properties at the right and left femoral neck and at the left femoral midshaft. Mechanical testing (axial and lateral compression of the femoral neck and 3pt bending of the midshaft) was performed at each location and strength indices based on pQCT parameters were calculated. Femoral neck properties decreased due to HU but recovered with respect to increase over HU, BL, and AC by the end of the recovery periods. Femoral midshaft properties were relatively unaffected, but did show slight decreases for older animals at month 10, which recovered during the two month recovery period. Femoral neck geometry exhibited increased endocortical resorption and periosteal apposition of the cortical shell which suggests that trabecular bone plays an important role in how the total bone is affected by HU. Densitometric properties were affected less by HU with respect to BL than were mechanical strength values. Results suggest that femoral neck is more affected by unloading than midshaft, particularly for multiple exposures of unloading. Also, aging does not appear to be a critical factor for bone loss due to HU for either femoral neck or midshaft.

BMPRII, a BMP type II receptor, plays an important role in regulating diverse biological events. BMPRII contains a long carboxyl tail domain, which is highly conserved among vertebrate species. The tail domain has been shown to regulate cytoskeleton remodeling, whereas the function in regulating canonical BMP signalling is not well studied. Here, I show that the BMPRII tail domain reduces the magnitude of BMP7-induced pSmad1 activation in the early stage, which also changes the magnitude of BMP target gene expression. Furthermore, my data also suggest that the BMPRII tail not only modulates BMP7-induced Smad1 carboxyl terminal phosphorylation, but also inhibits endogenous BMP signalling under overexpression conditions. Finally, BMP7 promotes Neuro2a neurite extension and I demonstrate that knockdown of BMPRII affects BMP7 induced neurite outgrowth. Altogether, these studies demonstrate that the BMPRII tail may play a role in regulating responsiveness to BMP7, and thereby modulates BMP7 dependent neurite extension in neuronal cells.

Gnathic changes after head and neck radiotherapy have not been thoroughly characterized radiographically. The objectives of this study are to characterize changes to the teeth and jaws on panoramic images following intensity modulated radiotherapy (IMRT), and to determine whether subject comorbidities and radiation dose affect these changes. This retrospective analysis reviews the charts and panoramic images of 126 head and neck cancer patients who received IMRT at Princess Margaret Hospital between January 1, 2005 and December 31, 2008. Of the 126 subjects, 75 (60%) showed changes on panoramic radiographs; 66 (88%) of which consisted of widened periodontal ligament spaces (WPLS). The median time to WPLS was 29 months after IMRT. Female sex and dose correlated with decreased time to WPLS. These results suggest that WPLS is a common radiographic sign following IMRT that may not require endodontic intervention as post-IMRT WPLS is unrelated to the pulpal status of the tooth.

BMPRII, a BMP type II receptor, plays an important role in regulating diverse biological events. BMPRII contains a long carboxyl tail domain, which is highly conserved among vertebrate species. The tail domain has been shown to regulate cytoskeleton remodeling, whereas the function in regulating canonical BMP signalling is not well studied. Here, I show that the BMPRII tail domain reduces the magnitude of BMP7-induced pSmad1 activation in the early stage, which also changes the magnitude of BMP target gene expression. Furthermore, my data also suggest that the BMPRII tail not only modulates BMP7-induced Smad1 carboxyl terminal phosphorylation, but also inhibits endogenous BMP signalling under overexpression conditions. Finally, BMP7 promotes Neuro2a neurite extension and I demonstrate that knockdown of BMPRII affects BMP7 induced neurite outgrowth. Altogether, these studies demonstrate that the BMPRII tail may play a role in regulating responsiveness to BMP7, and thereby modulates BMP7 dependent neurite extension in neuronal cells.

Gnathic changes after head and neck radiotherapy have not been thoroughly characterized radiographically. The objectives of this study are to characterize changes to the teeth and jaws on panoramic images following intensity modulated radiotherapy (IMRT), and to determine whether subject comorbidities and radiation dose affect these changes. This retrospective analysis reviews the charts and panoramic images of 126 head and neck cancer patients who received IMRT at Princess Margaret Hospital between January 1, 2005 and December 31, 2008. Of the 126 subjects, 75 (60%) showed changes on panoramic radiographs; 66 (88%) of which consisted of widened periodontal ligament spaces (WPLS). The median time to WPLS was 29 months after IMRT. Female sex and dose correlated with decreased time to WPLS. These results suggest that WPLS is a common radiographic sign following IMRT that may not require endodontic intervention as post-IMRT WPLS is unrelated to the pulpal status of the tooth.

Development of peak bone mass during childhood to early adulthood has been considered as a major determinate of risk of fracture and osteoporosis later in life. The purpose of this project was to determine the impact of food and nutrient intake on bone from childhood to early adulthood using mixed longitudinal data from the University of Saskatchewan Pediatric Bone Mineral Accrual Study (PBMAS). <p>To determine the role of consumption of milk products and vegetable and fruit on the total body-bone mineral content (TB-BMC) accrual in boys and girls from childhood to late adolescence, seven-year longitudinal data were used. Using a multilevel modeling statistical approach containing major biological and environmental factors, vegetables and fruit intake, calcium intake and physical activity were significant independent environmental predictors of TB-BMC in boys. <p>Change in the pattern of beverage intake of adolescents as a major component of nutrition transition has aroused health concerns such as obesity, tooth decay, and inadequate bone accrual. Beverage consumption and its relationship with calcium intake of grade 9 students from 1991 to 2004 was evaluated. Percent contribution of milk to total beverage intake was significantly decreased in boys and girls. A significant negative association between milk intake and consumption of non-carbonated soft drinks was observed in both genders. In girls only, a significant negative trend in calcium intake was observed over time. <p>Milk products, specifically fluid milk, were the major source of dietary calcium from childhood to early adulthood in both genders. There was a substitution of fluid milk by cheese, a decrease in vegetable and fruit intake, and the low intake of vitamin D in young adults, specifically females. <p>The effect of food and nutrient intake, measured at young adult age and previously in peri-adolescence, on bone mass was investigated. In males, the intake of calcium from peri-adolescence to early adulthood was sustained, whereas in females, there was a significant decrease. Height, weight, protein intake, physical activity and gender were the significant predictors of bone measures only in young adults who had consistent calcium intake from peri-adolescence. Collectively, the results of this study present the bone protective nutrients and food groups from childhood to early adulthood in our cohort. The food choices and dietary habits of the cohort change by age, but not in the favour of bones, with females more at risk. To prevent risk of osteoporosis, there should be promotion of a healthy dietary plan, not a single food group or nutrient, accompanied with an adequate level of physical activity.

No description available.

Development of peak bone mass during childhood to early adulthood has been considered as a major determinate of risk of fracture and osteoporosis later in life. The purpose of this project was to determine the impact of food and nutrient intake on bone from childhood to early adulthood using mixed longitudinal data from the University of Saskatchewan Pediatric Bone Mineral Accrual Study (PBMAS). <p>To determine the role of consumption of milk products and vegetable and fruit on the total body-bone mineral content (TB-BMC) accrual in boys and girls from childhood to late adolescence, seven-year longitudinal data were used. Using a multilevel modeling statistical approach containing major biological and environmental factors, vegetables and fruit intake, calcium intake and physical activity were significant independent environmental predictors of TB-BMC in boys. <p>Change in the pattern of beverage intake of adolescents as a major component of nutrition transition has aroused health concerns such as obesity, tooth decay, and inadequate bone accrual. Beverage consumption and its relationship with calcium intake of grade 9 students from 1991 to 2004 was evaluated. Percent contribution of milk to total beverage intake was significantly decreased in boys and girls. A significant negative association between milk intake and consumption of non-carbonated soft drinks was observed in both genders. In girls only, a significant negative trend in calcium intake was observed over time. <p>Milk products, specifically fluid milk, were the major source of dietary calcium from childhood to early adulthood in both genders. There was a substitution of fluid milk by cheese, a decrease in vegetable and fruit intake, and the low intake of vitamin D in young adults, specifically females. <p>The effect of food and nutrient intake, measured at young adult age and previously in peri-adolescence, on bone mass was investigated. In males, the intake of calcium from peri-adolescence to early adulthood was sustained, whereas in females, there was a significant decrease. Height, weight, protein intake, physical activity and gender were the significant predictors of bone measures only in young adults who had consistent calcium intake from peri-adolescence. Collectively, the results of this study present the bone protective nutrients and food groups from childhood to early adulthood in our cohort. The food choices and dietary habits of the cohort change by age, but not in the favour of bones, with females more at risk. To prevent risk of osteoporosis, there should be promotion of a healthy dietary plan, not a single food group or nutrient, accompanied with an adequate level of physical activity.

This thesis concentrates on discovering the best consolidant or consolidants for stabilizing a Columbian mammoth’s sub-fossilized mandibles, a distal femur, an ulna, a radius, and a tooth. It was recovered from a wet, sandy gravel pit owned by the Vernor Family located in Clute, Texas. Based on thermoluminescence dating, the mammoth dates to around 66,000 years ago. The bones are fragile and unstable. They retain a minute amount of organic material (collagen) and hydroxyapatite, but not enough to retain any structural support. Experiments and analyses were conducted on various bone samples to compare each of the following consolidants’ properties. The consolidants examined were silicone oil, polyvinyl acetate (PVA) with viscosity of 25, Acryloid B-72, Butvar 98, Starbond EM-02, methyltrimethoxysilane (MTMS), Paleo-bond, and Rhoplex (Primal) WS24. Stability, strength, and appearance were evaluated by measurable observations. The Scanning Electron Microscope (SEM) and the Environmental Scanning Electron Microscope (ESEM) at the Microscopy and Imaging Center at Texas A&M University were used to map penetration of these consolidants. SEM was utilized for both imaging and energy-dispersive x-ray spectroscopy (EDS) to examine the presence and absence of certain elements. ESEM was used to view consolidants at the microscopic level to further examine the bonding between the consolidant and the bone’s cellular structure. By examining and testing all the consolidants, methyltrimethoxysilane (MTMS) was chosen to stabilize the ulna, radius, left and right mandibles, distal femur, and tooth. This research opened new avenues to different methods in preserving sub-fossilized bone and broadens our understanding of bone conservation.