Diabetes is a chronic and debilitating disease that affects nearly half a billion people worldwide with the vast majority of diabetics suffering from Type 2 diabetes mellitus (T2DM), a disease characterized by insulin insensitivity that often requires pharmacotherapy to effectively maintain target blood sugar levels. The thiazolidinedione (TZD) class of drugs consists of oral hypoglycaemic agents used alone or in combination with other antidiabetic drugs to treat T2DM. The drugs within this class, which include rosiglitazone and pioglitazone, were originally heralded as providing novel first and second-line treatment of T2DM with glycaemic control and physiological effects comparable to, and in some cases, better than, first-line treatments such as metformin. However, over time they have also been associated with adverse cardiovascular, osteological, and carcinogenic effects in some, but not all clinical trials, observational studies, and meta-analyses. Given the conflicting evidence to date on the safety of TZD drugs, their role in the treatment of T2DM continues to be debated and epidemiological gaps remain. The objectives of this doctoral research are fourfold: 1) to conduct an in-depth review of the epidemiology of TZD pharmacotherapy including pharmacokinetics and modes of action, the results of previous studies investigating health risks and benefits associated with TZD treatment, and new and future uses for this class of drugs; 2) to determine whether diabetic patients treated with TZDs are at increased risk of adverse cardiovascular outcomes; 3) to assess whether TZD pharmacotherapy is associated with an increased risk of bone fractures and whether risks differ depending on fracture site and patient sex; and, 4) to investigate associations between TZD use and risk of bladder cancer. Specific research questions were investigated using nested case-control analyses designed to capture incident users of antidiabetic drugs and electronic health data from Cerner Health Facts®, an electronic medical record database that stores time-stamped patient records from more than 480 contributing hospitals throughout the United States. Findings from this work are reported in a series of manuscripts, including a published review paper. Key findings include: 1) TZD use was associated with an increased risk of incident myocardial infarction and congestive heart failure compared to never use of TZD drugs with a trend towards a potential early treatment effect within the first year of exposure to pioglitazone; 2) TZD use was associated with an increased risk of closed bone fractures among Type 2 diabetics with use of pioglitazone or rosiglitazone associated with an increased risk across multiple fracture sites in women, but only rosiglitazone use in men and only at peripheral fracture sites; 3) use of either pioglitazone or rosiglitazone were associated with an increased risk of incident bladder cancer compared to never users, however, a low number of bladder cancer cases resulted in underpowered analyses; and, 4) insulin use in a hospital setting may replace a patient's normal course of antidiabetic therapy which, when combined with other potential sources of bias in traditional nested case-control studies using hospital-based data, may lead to overestimation or underestimation of adverse health risks associated with non-insulin antidiabetic therapies. Although these findings warrant replication, the results of the research contained within this dissertation suggest that caution should be exercised when prescribing diabetic patients TZD drugs if they have cardiovascular, osteological, or carcinogenic risk factors. Additional pharmacovigilance studies should also continue to strive to better understand the health risks related to TZD therapy, especially as new therapeutic roles for TZDs in the prevention and treatment of some cancers, inflammatory diseases, and other conditions in non-diabetic populations are being explored.

Often bone fractures are joined by inserting metal plates and screws to hold the fragmented bone under compression. However, after the fractured bone is healed removing the screws leaves holes in the bone which takes months to fill up and heal completely. The goal of this research is to investigate those voids specifically in a finite element model of a femur. The holes were found to experience high stress that can easily lead to crack propagations during everyday activities. Finite element models of femurs were modeled after two common fracture fixation systems, specifically just after the plates, rods and screws are removed. To observe the stress levels bones are likely to experience, common mechanical tests that are relevant to or associated with common daily activities were performed. While the 3-point bending tests did not yield significant results, the compression and torsion tests produced high stress areas near the screw holes. In certain cases, the von Mises’ stress reached 3.66 x 106 N/mm2. Our finite element modeling seeks to establish groundwork for future explorations on the holes created by fracture fixation hardware. In the future, this work will lead to redesigning of fixation systems with reduced stress concentration around the holes. Therefore, the initiation of new cracks around these holes will be limited during everyday activity.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / O propósito do presente trabalho foi investigar a participação da proliferação celular e da expressão dos componentes da matriz extracelular na cascata de eventos do processo de reparo da fratura óssea, empregando as técnicas histológica, imunohistoquímica e morfométrica, em um modelo experimental padronizado para a indução da lesão na tíbia de ratos a partir do método empregado por Yuehuei e Friedman7. É importante padronizar um modelo de indução da fratura, para posterior investigação da participação das células e dos componentes da matriz extracelular no processo de reparo da fratura, considerando que o tempo de consolidação depende significantemente da natureza e do tipo da lesão produzida. Quarenta (n = 40) ratos Wistar foram submetidos a fratura . Os animais foram avaliados em oito (n = 8) grupos de cinco (n = 5) animais, cada grupo emperimental com 12, 24, 48, 72, 96, 144, 192 e 240 horas após a fratura (12h até 10 dias). As fraturas foram classificadas de acordo com o sistema de classificação internacional de fratura de Muller100, AO (Associação para Osteosíntese). Foram encontradas fraturas simples em 86% do total, sendo 68% de fraturas transversas e 18% de fraturas obliquas, 14% do total de fraturas foram complexas, sendo 8% de fraturas irregulares e 6% de fraturas segmentares. Esses resultados demonstram que o aparelho permite padronizar radiológicamente o tipo de fratura, caracterizado pela linha que separa os fragmentos ósseos. Os resultados qualitativos dos componentes da matriz extracelular para TGF-β, VEGF, colágeno I e II, osteopontina, proteoglicanos, fibras do sistema elástico com a coloração de resorcina funcsina de Weigert, e para proliferação celular pelo PCNA, assim como os resultados morfométricos, sugerem que a modulação da expressão dos componentes da matriz extracelular e a proliferação celular durante o processo de reparo da fratura não é homogênea para todos os componentes teciduais, dependendo significantemente das tensões locais geradas pelo tipo da linha de fratura que pode ser determinante no tempo de regeneração do osso e na qualidade da restauração das propriedades biomecânica. Nossos achados podem contribuir para melhor compreensão da reparo de fratura óssea e para novas abordagens terapêuticas que considerem as propriedades biomecânicas do tecido ósseo em reparo nas suas diferentes etapas / The purpose of this study was to investigate the role of cells proliferation and extracellular matrix components expression in the process of bone fracture repair. To do so it used histological techniques, immunohistochemistry and morphometric analysis as well as a standardized experimental model for the induction of injury to the tibia of rats as proposed by Yuehuei and Friedman7. It is important to standardize a model of fracture induction for further investigation of the involvement of cells and extracellular matrix components in the fracture repair process, whereas the healing time depends significantly on the nature and type of lesion produced. Forty (n = 40) Wistar rats were subjected to fracture. The animals were divided into eight (n = 8) groups of five (n = 5). Each subgroup was observed after 12, 24, 48, 72, 96, 144, 192 and 240 hours of fracture (12 to 10 days). Immediately afterwards, the fractures were classified according to the system of international classification of fracture by Muller100, AO (Association for Osteosynthesis). Simple fractures were found in 86% of the total, among them, 68% were transverse and 18% were oblique. Complex fractures were found in 14% of the cases, among them 8% were irregular and 6% were segmental. These results demonstrated that the device enables researchers to standardize the type of fracture by X-ray, marked by the line separating the bone fragments. The qualitative results of the cells and extracellular matrix components of TGF-β, VEGF, PCNA, collagen I and II, osteopontin, proteoglycans, elastic fibers system with resorcin funcsin of Weigert, as well as the morphometric results suggest that the repair process of the fracture is not homogeneous for all components. Expression of the extracellular matrix components and cell proliferation modulation significantly depends on the local stresses generated by the type of the fracture. Such type can be decisive in determining time duration for bone regeneration and quality of the biomechanical properties restoration. Our findings may contribute to better understanding of bone fracture repair and for new therapeutic approaches that consider the biomechanical properties of bone tissue in repair in its different stages

Orientador: Roger William Fernandes Moreira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-23T17:35:55Z (GMT). No. of bitstreams: 1 Rodrigues_DanilloCosta_M.pdf: 1685806 bytes, checksum: 0e90fd8fb32a562bcf7161f1f78bfab7 (MD5) Previous issue date: 2013 / Resumo: O presente estudo teve como propósito analisar a resistência mecânica de duas marcas de fixação do sistema 1,5mm através de teste mecânico de carregamento linear em dois métodos de fixação em modelos de hemimandíbulas de alumínio com fraturas simuladas e realizar análise fractográfica. Foi realizada a confecção de quatro estruturas de alumínio semelhantes a hemimandíbula, sendo utilizada duas hemimandíbulas para cada grupo de estudo. As mesmas foram fixadas com placas e parafusos das marcas Tóride® e Traumec®. No grupo I foi empregada uma placa reta de titânio de quatro furos na zona de compressão e outra na zona de tensão mandíbular; e no grupo II, foi empregada apenas uma placa reta de quatro furos na zona neutra. Para os testes mecânicos, foi utilizada a máquina para ensaio universal mecânica Instron® modelo 4411 até ocorrer a falha total do sistema de fixação (fratura da placa). Em seguida, as amostras foram submetidas a análises fractográficas das superfícies fraturadas com microscópio eletrônico de varredura FEI®. Foi aplicada a Análise de Variância (ANOVA) dois fatores e o teste de Tukey com significância de 5%. A fixação com duas placas retas de quatro furos apresentou maior resistência à carga (p<0,01) em relação ao grupo de apenas uma placa, independente da marca comercial. A marca Tóride® apresentou média de deslocamento de pico maior que as placas Traumec® quando avaliadas nos grupos com uma placa e extensão de carga no deslocamento de 5mm. As amostras romperam por sobrecarga dúctil, por falha mecânica caracterizada por dano alveolar / Abstract: The purpose of this study was to analyze the mechanical strength of two brands of 1.5 mm system fixation through mechanical linear load test in two fixation methods in aluminum hemimandibles with simulated body fractures and perform fractographic analysis of the samples. Four aluminum structures similar to hemimandibles were fabricated with a linear sectioning simulating a fracture of mandibular body and two hemimandibles were used in each group for posterior fixation with plates and screws with two national brands: Toride® and Traumec®. The group I was fixed with a straight titanium plate with four holes in the compression zone and another one in the tension zone. Group II was fixed with a straight plate with four holes in the neutral zone. For mechanical testing, a universal mechanical testing Instron ® Model 4411 was used and the test was made until final failure of the system (fracture plate). Then, the samples were submitted to fractographic analysis through a scanning electron microscope FEI ®. A analysis of variance (ANOVA) Two-way and Tukey test with 5% significance (?= .05) were applied for statistical analysis. The fixation method with two straight plates showed a higher load resistance (p<0.01) when compared to the group of only one plate, regardless of the brand. The brand Toride® showed an average of peak displacement higher than Traumec® when the groups with only one plate with the extension of 5mm were evaluated. All the samples fractured by ductile overload, characterized by alveolar micromechanisms / Mestrado / Cirurgia e Traumatologia Buco-Maxilo-Faciais / Mestre em Clínica Odontológica

This study investigates the skeletal muscle repair and regeneration process following blunt trauma injury in murine models. Skeletal muscle injury is recorded most often in sports injuries and include strains and sprains, contusions, and bruising, however, there is growing consensus about the role skeletal muscle plays in the reparative process of bone fractures. Skeletal muscle stem cells or satellite cells are mesenchymal stem cell derived cells that exist between the basal lamina and cell membrane of muscle fibers usually in close proximity to capillary beds. After a traumatic injury, satellite cells respond to the influx of signaling from immune cells, oxygen tension, and myogenic proteins which influence differentiation into myoblasts for repair of tissue damage. Research continues to elucidate the relationship between bone and skeletal muscle following trauma injuries. Skeletal muscle stem cells play a vital role in fracture healing, and in certain conditions, are even induced into the osteogenic pathway. The goals of this study are to characterize the temporal progression of myogenesis during muscle repair that will be used with future studies of muscle and bone injury. And to identify potential crosstalk mechanisms between muscle and bone repair during trauma. In our experiment model trauma was introduced to mice with a modified muscle contusion device where a weight was dropped onto the femoral quadriceps muscles and the quadriceps and biceps muscle tissues were harvested at post-operative days (POD) 2, 4, 12, 16, and 24. Reverse-Transcriptase Quantitative Polymerase Chain Reaction was used to analyze gene expression profiles for satellite/stem cells (Pax7 and Prx1), muscle regeneration (MyoD, Myf5, Myl2, and Myh1), angiogenesis (VegfA, VegfR2), myokine (Myostatin and IL6), and BMP signaling (ID1). Our findings indicate that both Pax7 and Prx1 expression slightly decreased after injury but showed a significant (p<0.05) increase and peak of expression at POD 16 in the femoral quadriceps muscles. The early myogenic genes, MyoD and Myf5 peaked early at POD 4 while the adult myofiber markers, Myl2 and Myh2, peaked later at POD 16 in the femoral quadriceps muscles. Only slight changes were observed in the femoral biceps muscles. The angiogenic genes peaked at POD16 in the femoral quadriceps muscles and POD 12 in the femoral biceps muscles. The expression of Myostatin, an inhibitor of muscle mass, decreased early (POD 4 and 12) however showed a non-significant increase at POD 16 in the femoral quadriceps muscles. Lastly, the expression of ID1, which is downstream target of BMP signaling peaked early at POD 4 in the femoral quadriceps muscles. These data indicates that stem/satellite cells decrease in response to muscle injury but by POD 4, myogenic commitment and programming occurs. While early myogensis occurs, BMP signaling peaks and Myostatin expression decreases suggesting a coordinated event. Adult myofiber regeneration occurs in parallel to angiogenesis. The myogenic events were primarily isolated to the injured femoral quadriceps muscles. This model of muscle injury can be used to study muscle regeneration within context to bone injury.

<p>Approximately 6.3 million bone fractures occur annually in the USA, resulting in considerable morbidity, deterioration in quality of life, loss of productivity and wages, and sometimes death (e.g. hip fractures). Although anabolic and antiresorptive agents have been introduced for treatment of osteoporosis, no systemically-administered drug has been developed to accelerate the fracture healing process. To address this need, we have undertaken to target a bone anabolic agent selectively to fracture surfaces in order to concentrate the drug’s healing power directly on the fracture site. We report here that conjugation of dasatinib to a bone fracture-homing oligopeptide via a releasable linker reduces fractured femur healing times in mice by ~60% without causing overt off-target toxicity or remodeling of nontraumatized bones. Thus, achievement of healthy bone density, normal bone volume, and healthy bone mechanical properties at the fracture site is realized after only 3-4 weeks in dasatinib-targeted mice, but requires ~8 weeks in PBS-treated controls. Moreover, optimizations have been implemented to the dosing regimen and releasing mechanisms of this targeted-dasatinib therapy, which has enabled us to cut the total doses by half, reduce the risk of premature release in circulation, and still improve upon the therapeutic efficacy. These efforts might reduce the burden associated with frequent doses on patients with broken bones and lower potential toxicity brought by drug degradation in the blood stream. In addition to dasatinib, a few other small molecules have also been targeted to fracture surfaces and identified as prospective therapeutic agents for the acceleration of fracture repair. In conclusion, in this dissertation, we have successfully targeted dasatinib to bone fracture surfaces, which can significantly accelerate the healing process at dasatinib concentrations that are known to be safe in oncological applications. A modular synthetic method has also been developed to allow for easy conversion of a bone-anabolic warhead into a fracture-targeted version for improved fracture repair.</p><p></p>

No description available.

TP508 is a 23 amino acid peptide derived from human prothrombin. It helps wound healing in both soft tissues and bones. In our previous study, we have demonstrated that TP508 retains chondrocyte in a less mature differentiation state while expanding the cartilage mass, indicating it may partly help bone healing by expand the cartilage template in the endochondral bone formation stage. In our current study, we want to demonstrate that TP508 also blocks chondrocyte apoptosis. We used rat costochondral growth plate chondrocytes as our model. We first established chelerythrine as an apoptogen in chondrocytes. TP508 is able to block apoptosis caused by chelerythrine. Chelerythrine also causes an increase in NO production, which is known to cause both pathological and physiological apoptosis of chondrocyte, and blocking NO production can in turn block apoptosis caused by them. TP508 is also able to block NO production caused by chelerythrine. Therefore, TP508 may partially block chondrocyte apoptosis by blocking NO production. From all above, we conclude that besides decreasing chondrocyte differentiation, TP508 also blocks their apoptosis, so as to conserve the cartilage template in endochondral bone formation

Fracture healing requires a series of events including inflammatory response and callus formation, callus remodeling and bone healing. Fracture healing is a complex process, there are several overlapping phases , including inflammation , cartilage formation and bone remodeling, there are many internal or external factors could impact on fracture healing, leading to delayed bone healing or non healing. The global androgen receptor knockout (GARKO) mice has been know to reduce bone mass in endochondral bone and osteoblast mineralization, but the impact for callus formation in fracture healing is still unclear. The goals of study is to investigate the role of androgen and androgen receptor in wild-type (WT) mice and GARKO mice after fracture healing during callus formation and bone mineralization and bone remodeling. Therefore, long-term animal experiments observed by micro-computed tomography to study the roles of androgen and androgen receptor on the process and mechanisms of fracture healing is necessary. We applied in vivo micro-computer tomography (Micro-CT) to build up the three-dimensional model images at different time points for wild-type mice and GARKO mice after fracture healing and observe the bone healing process of micro-structure of the development of callus during fracture healing. The callus tissue morphology observed by histological staining to study the proportion and position of collagen, fibrous tissue and bone. The results show that the healing of WT mice is better than GARKO mice. GARKO mice develop smaller callus size and less bone volume and show delayed healing. In general, orchiectomy (ORX) decreases callus size in WT mice but not in GARKO mice. However, the healing rate of elderly GARKO mice is not obvious in comparison with young GARKO mice. Together, our study demonstrated that the androgen and androgen receptor regulate fracture healing and play an important role in bone repair and healing. Our mouse model may be used for the therapeutic drug screening of bone fractures caused by osteoporosis.

Non-union bone fractures are a standing problem for clinical treatments. It has been found that the exogenous growth factor recombinant human bone morphogenetic protein-2 (rhBMP-2) induces bone healing in potential non-union fractures. However, the currently used clinical dose of rhBMP-2 is high and causes side-effects. Mechanical loading is known to enhance the induced effects of rhBMP-2 in bone healing, which may lead to a reduced required dose. Yet, the exact underlying mechanism is unknown. To further investigate the combined role of mechanical loading and rhBMP-2 in the early phase of fracture healing a 2D computational model was developed. The model uses a lattice-based approach where biological rule-based events are combined with finite element analysis to simulate both untreated bone healing progression and when subjected to mechanical loading and rhBMP-2. Two healing cases were investigated:  normal fracture healing in a small bone defect (1 mm gap) and non-union fracture healing in a large bone defect (5 mm gap). By varying the magnitude and timing of applied load as well as the rhBMP-2 dose, a combination that would reduce the currently used rhBMP-2 dose and still enable healing in a large bone defect was searched. The model could simulate fracture healing in a large bone defect when subjected to rhBMP-2, independently of the applied load. Also the expected non-union result in a large bone defect without applied rhBMP-2 was obtained. The model could not capture normal fracture healing in a small bone defect as well as bone remodelling. It was found that a 50 % reduced rhBMP-2 dose could not induce healing in a large bone defect when applied separately but when applied together with load. Additionally, this combination of stimulation gave similar results compared to other combinations using higher rhBMP-2 doses. To conclude, even though the model was able to replicate some of the healing events seen experimentally, it is in need of modifications to correct current deficiencies. Still, after some further development and validation, the model has the potential to be used in future studies of fracture healing when influenced by mechanical loading and rhBMP-2. The found possibility for a reduced dosage of rhBMP-2 when applied together with load has to be further investigated before any conclusions can be drawn.