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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
311

Osteoporotic Fractures and Heart Failure in the Community

Gerber, Yariv, Melton, L. Joseph, Weston, Susan A., Roger, Vronique L. 01 May 2011 (has links)
Purpose: Recent findings suggest a role for heart failure in the etiology of osteoporotic fractures, yet the temporal sequence of occurrence of the 2 conditions needs clarification. Methods: Using the Rochester Epidemiology Project, the authors conducted a 2-phase study: a case-control study compared osteoporotic fracture history among Olmsted County, Minnesota, residents newly diagnosed with heart failure in 1979-2002 with age- and sex-matched community controls without heart failure (961 pairs; mean age 76 years; 54% women). Both groups were then followed to July 2009 to evaluate their subsequent fracture risk in a cohort study. Results: Prior fractures were more frequent in heart failure cases than controls (23.1% vs. 18.8%, P = .02). The adjusted odds ratio (OR) for heart failure associated with prior fracture was 1.39 (95% confidence interval [CI], 1.07-1.81), mainly driven by hip fractures (OR 1.82; 95% CI, 1.25-2.66) with little or no association with other fractures. Over a mean follow-up of 7.5 years, 444 individuals developed subsequent osteoporotic fractures. The adjusted fracture risk was marginally elevated in heart failure patients compared with controls (hazard ratio [HR] 1.32; 95% CI, 0.98-1.79), again largely attributable to hip fractures (HR 1.58; 95% CI, 1.03-2.41). Conclusions: In this community, the association with fracture risk was about as strong before as after the diagnosis of heart failure and was nearly entirely attributable to hip fractures. Additional work is needed to identify common underlying mechanisms for heart failure and hip fracture, which may define prevention opportunities.
312

Review of Treatment Modalities for Postmenopausal Osteoporosis

Hamdy, Ronald C., Chesnut, Charles H., Gass, Margery L., Holick, Michael F., Leib, Edward S., Lewiecki, Michael E., Maricic, Michael, Watts, Nelson B. 01 October 2005 (has links)
This review summarizes and updates data presented at recent annual Southern Medical Association conferences on postmenopausal osteoporosis. As part of any osteoporosis treatment program, it is important to maintain adequate calcium and 25-hydroxyvitamin D levels either through diet or supplementation. Among the available pharmacologic therapies, the bisphosphonates alendronate and risedronate have demonstrated the most robust fracture risk reductions- approximately 40 to 50% reduction in vertebral fracture risk, 30 to 40% in nonvertebral fracture risk, and 40 to 60% in hip fracture risk. Ibandronate, a new bisphosphonate, has demonstrated efficacy in reducing vertebral fracture risk. Salmon calcitonin nasal spray and raloxifene demonstrated significant reductions in vertebral fracture risk in pivotal studies. Teriparatide significantly reduced vertebral and nonvertebral fracture risk. Drugs on the horizon include strontium ranelate, which has been shown to reduce vertebral and nonvertebral fracture risk, and zoledronic acid, an injectable bisphosphonate that increased bone density with once-yearly administration.
313

Bone mechanobiology of modeling and remodeling and the effect of hematopoietic lineage cells

Robinson, Samuel Thomas January 2020 (has links)
Osteoporosis is characterized by chronic bone loss and deterioration of microarchitecture that can leave patients more susceptible to costly and debilitating fractures. A variety of treatment options have been developed that target different cells and pathways to disrupt its progression. In addition to pharmaceutical options, regular exercise is recommended, as external, mechanical loading has long been recognized as a stimulus bone can use to regulate its size and shape to meet mechanical demands. While bone cell signaling is undoubtedly multifaceted, meaningful changes in bone mass ultimately result from the actions of bone-forming osteoblasts and bone-resorbing osteoclasts. To this end, therapies are most traditionally described through their impacts on these cells, and are broadly categorized as anabolic (activating osteoblasts and having bone-building effects, such as parathyroid hormone injections and sclerostin antibody treatment), or anti-resorptive (targeting osteoclasts and slowing resorption, such as bisphosphonates and denosumab). Bone formation and resorption are rooted in two overarching processes: coupled bone remodeling (resorption followed by formation in the same space) and uncoupled bone modeling (formation or resorption occurring independently). Hematopoietic-lineage cells have an inherent, established role in bone remodeling, as descendent osteoclasts perform the resorption to initiate remodeling, but have only more recently been implicated as potential orchestrators of anabolic bone modeling in their preosteoclastic states, suggesting the extent of their differentiation may be a mechanism steer the bone response between maintenance remodeling and adaptive modeling regimes. Understanding how pharmaceutical treatments and mechanical loading work through these regimes, augment intrinsic sensing mechanisms, or tilt local signals to favor one or the other may provide valuable insight into optimizing or combining current treatments, and potentially suggest new therapeutic avenues. We first establish a method for quantifying modeling and remodeling in vivo using image registration on weekly micro-computed tomography scans. This technique is implemented in a study to assess the independent and combined effects of daily mechanical loading and parathyroid hormone injections in mice. We found that both resulted in significant increases in bone formation through anabolic modeling and remodeling, and while the modeling effects were usually additive or independent, the remodeling response was synergistic. Additionally, while PTH tended to exert its influence indiscriminately, the loading response was more targeted and pronounced in ways that mirrored local mechanical strains. Interestingly, this held true for catabolic modeling as well, where we observed a previously unreported phenomenon of load-induced increases in catabolic modeling in areas of low strain on the endosteal surface of cortical bone. We then began targeted interventions into the hematopoietic lineage cells, starting at their most terminally differentiated state in bone, the osteoclast. Using an injectable osteoclast maturation inhibitor, osteoprotegerin (OPG), we observed how arresting this process influenced modeling and remodeling in response to loading in normal mice, and in mice genetically modified to reduce sclerostin expression. We observed the expected reductions in catabolic modeling regardless of genotype. We also found that in sclerostin-depleted mice treated with OPG, anabolic modeling was elevated, and there was no added benefit of mechanical loading to the response in trabecular and endosteal compartments, suggesting the controlled manipulation of these factors can fully recapitulate the intrinsic mechanosensing capabilities. Since the loading response is largely modeling-based, these findings support the hypothetical determinant of the modeling/remodeling response being the preosteoclast/osteoclast ratio in these areas. In contrast, however, on the periosteal surface a pronounced load-induced anabolic modeling response persisted in all treatment conditions, suggesting the unique cell populations in the periosteum may have more robust, more finely tuned, or differentially regulated mechanosensing mechanisms. Finally, to probe the hematopoietic lineage further upstream and address the other side of the preosteoclast/osteoclast hypothesis, we utilized a novel genetically modified mouse model that allows for inducible macrophage (preosteoclast) ablation. Modeling and remodeling dynamics in response to loading were quantified in mice with normal or depleted macrophage quantities with concurrent normal or genetically-reduced sclerostin expression. In agreement with our hypothesis linking these cells to the anabolic modeling response, macrophage ablation resulted in significantly less anabolic modeling on trabecular and endosteal surfaces, which was not recovered by mechanical loading in either wild type or sclerostin deficient mice. Again, however, the periosteal surface was unique. Macrophage ablation did not reduce anabolic modeling on the periosteal surface, and loading still significantly increased it, regardless of sclerostin expression. Thus, similar to our findings with osteoprotegerin, a unique contrast existed between macrophage/preosteoclast ablation drastically reducing anabolic modeling and nullifying any mechanoresponse on trabecular and endosteal surfaces, but not the periosteal surface. Taken together, these studies outline and implement a novel method to quantify modeling and remodeling in response to loading and clinically relevant treatments, with an emphasis on perturbations of the hematopoietic lineage. Concurrent stimuli are used to observe and quantify overlaps and augmentations in treatment efficacies, with a focus on mechanisms related to mechanoadaptation. Future work will focus on targeted approaches to identify unique mechanosensing factors driving the periosteal response, more sophisticated data analysis tools to observe to what extent localized bone metabolism can be predicted by strain and morphology, and the protein and cellular-level dynamics that underlie our findings. As an addendum, a novel bone morphological parameter is described. A trabecular-cortical interface surface area metric (iSAM) is quantified on a set of cadaver bone segments from clinical high-resolution peripheral quantitative computed-tomography scans (a clinical analog to micro-computed tomography). iSAM is shown to correlate with stiffness and ultimate force derived from mechanical testing of the same samples, and improve correlations gleaned from traditional morphometric parameters alone.
314

Fragment reattachment with light-cured glass-ionomer

Minutillo, Anthony L., 1965- January 1996 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / This investigation examined the relationships among light cured glass ionomer liner, light cured glass ionomer base, and composite resin material in the reattachment of fractured anterior tooth fragments. Seventy-five bovine incisor teeth were fractured and luted back together with three different materials (Universal Bonding Agent/TPH Composite Resin; VariGlass VLC Liner; VariGlass VLC Base, LD Caulk Div Dentsply Int Inc, Milford, DE) of equal number. The reattached fragments were subjected to thermocycling with a 40° C differential and then were loaded until the force required to detach the fragment was reached. The mean dislodgment strengths were 36.8 (± 25.6)kg for the composite resin, 36.4 (± 26.7)kg for the glass ionomer base, and 31.4 (± 29.S)kg for the glass ionomer liner. Analysis of variance demonstrated no significant difference between the three groups at p≤0.05. Also examined was the type of fracture after reattachment. Of the sixty-five teeth that were studied microscopically, 84.6 percent of the fractures were cohesive in nature, thus a breakdown occurred within the material itself.
315

The Impact of Oral Bisphosphonate Therapy on Vertebral Morphometry in Patients with Duchenne Muscular Dystrophy and Glucocorticoid-Induced Osteoporosis

Nasomyont, Nat 15 June 2020 (has links)
No description available.
316

Understanding the Depth and Nature of Flow Systems in the Nashoba Terrane, Eastern Massachusetts, U.S.A.

Diggins, John P 01 January 2009 (has links) (PDF)
Igneous and metamorphic rock units have long been considered marginal aquifers yet they are a significant source for potable drinking water in many areas worldwide. Additionally, use of these systems is on the rise due to many factors including, contamination and overuse of surficial systems, as well as expanding population and drought. The Nashoba Terrane is a fault-bounded block of high-grade, steeply dipping metavolcanic and metasedimentary rock located in eastern Massachusetts, U.S.A. The Nashoba is northeast trending, extending from Oxford, MA to the Gulf of Maine south of Newburyport, MA. Seventeen previously drilled wells throughout the Nashoba were selected for use in this study. The goal of this study was to characterize the hydrogeologic system of the Nashoba Terrane. Wells studied were in three bedrock types: granite, schist and amphibolite. Three fracture types were identified: FPF, subhorizontal unloading joints and tectonic joints. Several major fracture orientation sets were also identified including northeast trending FPF, east-west trending and north-south trending tectonic joints as well as northwest trending tectonic joints. Dominant sets varied in the three rock types and the frequency of fractures was found to decrease with depth. Only four percent of all fractures measured in this study were flowing. Approximately 32% of the flowing fractures were northeast trending, 17% of subhorizontal fractures were flowing and the remaining 51% were of variable orientation and dip. In general, the orientation of fractures was not found to determine whether a fracture flows, nor was rock type a significant determinant of flow. There was no flow identified below 170 meters and the majority of flow in the Nashoba Terrane is constrained to the upper 100 meters. This is most likely due to decreased fracture frequency and permeability with depth. This study is significant to the search for a sustainable groundwater source in bedrock because results show that the few fractures are actually contributing to flow and that flow is primarily occurring near the surface.
317

Radiographic Union Score for Tibia (RUST) scoring system in adult diaphyseal femoral fractures treated with intramedullary nailing: an assessment of interobserver and intraobserver reliability

Panchoo, Pravesh 14 April 2023 (has links) (PDF)
Objectives The Radiographic Union Score for Tibia (RUST) scoring system has been validated in multiple studies assessing the healing of tibial fractures. Our objective was to assess the inter and intraobserver reliability for the RUST in diaphyseal femoral fractures treated with intramedullary (IM) nailing. Patients and Methods A total of 60 sets of anteroposterior (AP) and lateral radiographs of diaphyseal femoral fractures treated by reamed IM nailing were randomly selected from a prospectively collected database. The 60 sets of radiographs were then scored by three reviewers using the RUST system. Interobserver reliability was measured at initial scoring. The 60 sets of radiographs were scored again by the three reviewers to calculate the intraobserver reliability. Results The RUST scores ranged from 4 to 12 with a mean score of 11.3 ± 1.3. The interobserver intraclass correlation coefficient (ICC) was 0.87 (95% CI, 0.81-0.92) and the intraobserver ICC was 0.91 (95% CI, 0.88-0.94), which indicated excellent agreement. Conclusion This study demonstrated that the RUST system can be used reliably in the assessment of healing in diaphyseal femur fractures treated by reamed intramedullary nailing, with excellent interobserver and intraobserver reliability.
318

Application of Combined Jointed Media and Discrete Slip Plane Characteristics to Subsidence Predictions

Basinger, David W. 01 December 1984 (has links) (PDF)
This thesis presents an application of a numerical formulation incorporating the effects of joints, cracks, and fractures to a soil subsidence predictions problem, and the extension of that formulation to combined discrete slip planes and jointed media continua formulations. The results obtained are compared to each other and to a physical centrifuge simulation performed previously on the same problem.
319

Chronic Liver Disease and the Risk of Osteoporotic Fractures: A Meta-Analysis

Hidalgo, Diego F., Boonpheng, Boonphiphop, Sikandar, Sehrish, Nasr, Lubna, Hidalgo, Jessica 16 September 2020 (has links)
Introduction Chronic liver disease (CLD) causes more than 1 million deaths every year and remains a pandemic in the last decade affecting more than 600,000 patients in the United States. Previous studies found patients with CLD had increased risk of osteoporosis, so fractures were inferred to be complications of this condition. The aim of this meta-analysis is to summarize the best evidence that correlates CLD patients and the risk to develop osteoporotic fractures versus control patients without CLD. Methods A review of the literature using MEDLINE and EMBASE database was performed during December 2017. We included cross-sectional and cohort studies that reported relative risks (RR), odds ratios (OR) and hazard ratios (HR) comparing the risk of developing osteoporotic fractures among patients with CLD versus patients without CLD. Pooled OR and 95% confidence interval (CI) were calculated using generic inverse- variance method. The Newcastle-Ottawa scale was used to determine the quality of the studies. Effect estimates from the individual study were extracted and combined using the random-effect, generic inverse variance method of DerSimonian and Laird. Results After the review of the literature, seven studies fulfilled the eligibility criteria established during the analysis. Significant association was found between CLD and osteoporotic fractures with a pooled OR of 2.13 (95% CI, 1.79 - 2.52). High heterogeneity among the studies was found (I2=88.5). No publication bias was found using Egger regression test (p=0.44). Conclusion We found a significant association between CLD and the risk of developing osteoporotic fractures. The calculated risk was 2.13 times higher for patients with CLD when compared with controls. The results showed high heterogeneity but no publication bias. More prospective studies are needed to fully understand the mechanisms involved in loss of bone density and osteoporotic fractures in order to improve the morbidity associated with this disease.
320

Predictors of Morbidity and Mortality Among Thoracic Trauma Patients

McConnell, Jeremy Patrick 01 January 2019 (has links) (PDF)
Background. There are roughly 300,000 rib fractures treated for in the United States each year. These represent 10-26% of thoracic trauma injuries and have about a 10% mortality rate. There is a common belief that mortality in rib fracture patients can be contributed to the diagnosis of pneumonia, but this study does not support that claim. Purpose. To determine the predictors of morbidity and mortality in rib fracture patients. Methods. Using a level 1 trauma center patient registry, we retrospectively analyzed all patients that were admitted with at least one rib fracture (n=1,344). All predictors were analyzed with linear regressions. Results. The average age of the patients was 55.48 ± 20.29 years old and ranged between 15 and 98. ISS (OR: 1.0508, p<0.001), bilateral fractures (OR: 1.9495, p = 0.009) and pulmonary contusion (OR: 1.7481, p = 0.022) were all significant predictors of pneumonia. The age of the patient (OR: 1.0467, p < 0.001), ISS (OR: 1.0585, p <0.001), having 6 or more fractured ribs (OR: 3.1450, p < 0.001), the presence of hemothorax (OR: 2.5063, p = 0.048), and the use of mechanical ventilation (OR: 13.2125, p < 0.001) were all significant predictors of mortality. Flail segments (OR: 1.9871, p = 0.067), ISS (OR: 1.1267, p < 0.001), pulmonary contusions (OR: 1.5329, p = 0.047), pneumothorax (OR: 1.4372, p =0.073) and pneumonia (OR: 21.4516, p < 0.001) are all predictors of requiring mechanical ventilation. Conclusion. There are many studies that indicate rib fracture patients who are diagnosed with pneumonia have a higher risk or mortality. With this in mind, the logical course of treatment would be to counteract the complications pneumonia brings as to reduce the risk or mortality. To do this, it is recommend the patient be put on mechanical ventilation. While this has been seen to help with pneumonia patients, this study provides evidence that health care professionals should look for ways to reduce the need for mechanical ventilation instead of using it to combat the pneumonia.

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