Made available in DSpace on 2015-12-10T14:22:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-07-24. Added 1 bitstream(s) on 2015-12-10T14:28:32Z : No. of bitstreams: 1 000852670.pdf: 3896062 bytes, checksum: 5f9c83850e52e60d31d9bbbf47ddb6e4 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / As tromboses podem ocorrer frequentemente em equinos como decorrência de coagulopatia intravascular disseminada, hipóxia, endotoxemia, cólica e laminite ou ainda por processos iatrogênicos. Porém, há poucos estudos em relação à cirurgia vascular e alterações morfológicas deste processo em equinos. Este trabalho teve por objetivo estudar a morfologia e os aspectos histopatológicos da veia cefálica em dois modelos experimentais. Foram utilizados 10 equinos hígidos, divididos em dois estudos: Estudo Trombose (ET), avaliou-se os aspectos histopatológicos da veia cefálica na tromboflebite aguda induzida. Estudo Fogarty (EF) avaliou-se os aspectos histopatológicos após a aplicação imediata do cateter de Fogarty. Para obtenção de base morfológica para avaliação das túnicas, coletou-se uma amostra controle (AC) de veia cefálica hígida. Nos animais do ET, foi realizada a indução química da trombose na veia cefálica e após 24 horas procedeu-se a coleta de segmento venoso para avaliações histopatológicas. Nos animais do EF, foi realizada a passagem do cateter de Fogarty na veia cefálica hígida e coleta imediata do segmento venoso. Os segmentos da veia cefálica foram divididos em segmento proximal e distal e analisados quanto à morfologia e histometria. Os segmentos do ET apresentaram espessamento da parede vascular, com desorganização das células musculares lisas, maior quantidade de matriz extracelular e alteração morfológica das células endoteliais em relação à AC. Os segmentos do EF apresentaram alterações morfológicas das células endoteliais e menor quantidade de células musculares lisas em relação à AC. A partir destes resultados, podemos concluir que a trombose induziu resposta inflamatória na parede vascular e espessamento das túnicas associada à presença do trombo. O EF apresentou alteração morfológica das células endoteliais em resposta imediata à passagem... / Thrombosis can occur frequently in horses as a consequence of disseminated intravascular coagulopathy, hypoxia, endotoxemic, colics and laminitis or a iatrogenic process. However, there are few studies regarding vascular surgery and morphology changes of this process in horses. This research aimed to study the morphology and histopathological aspects of the cephalic vein in two experimental models. Ten healthy horses, was divided into two studies: Thrombosis study (ET), were used to evaluate the histopathological aspects of the cephalic vein in induced acute thrombophlebitis. Fogarty study (EF) was evaluated histopathological aspects after the immediate application of the Fogarty catheter. To achieve morphological based measures of the coats, were collected a sample control (AC) from a healthy cephalic vein. The animals of ET, chemical induction of thrombosis was performed in the cephalic vein and 24 hours proceeded the segment collection of the vessel for histological evaluation. The animals of EF, were submitted to the passage of a Fogarty catheter in the patent and healthy cephalic vein, followed by immediate collection of a segment venous. The cephalic vein segments were divided into proximal and distal and analyzed for morphology and histometry. The ET segments showed thickening of the vascular wall, with disorganization of the smooth muscle cells, increased amount of extracellular matrix and morphological alteration of endotelial compared to AC. The segments EF showed morphological changes in endothelial cells and fewer smooth muscle cells in relation to AC. From these results, we can conclude that thrombosis induced inflammatory response in vascular wall thickening and coats related to the presence of thrombus. The EF presented morphological alteration of endothelial cells in immediate response to the passage of the catheter, but so did the segment where there was the passage of the catheter

Background: Up to 40% of trauma patients die during the first 24 hours after injury due to massive hemorrhage. In patients who survive this critical time period, no information is available on rates of delayed major bleeding or factors associated with delayed major bleeding. Methods: A retrospective chart review of 150 critically ill adult trauma patients was used to determine the incidence of delayed major bleeding events. Cox proportional hazards multivariate analysis was performed to assess for risk factors associated with delayed major bleeding events. The anticipated rate of delayed major bleeding events was 10%. Results: The incidence of delayed major bleeding in this cohort of critically ill trauma patients was 44%. Predictors that were statistically significantly associated with delayed major bleeding included: male gender, pre-injury use of the antiplatelet agents aspirin and/or clopidogrel, presence of intracranial bleeding, higher injury severity scores, requirement of massive transfusion, and low pH values. Use of anticoagulant prophylaxis was not associated with delayed major bleeding. Conclusion: The rate of delayed major bleeding was higher than estimated. Larger retrospective and prospective cohorts are needed to confirm these findings.

Silk is a natural protein produced by members of the class Arachnida (over 30,000 species of spiders) and by several worms. Silk-based materials have been investigated for medical and biotechnological applications for many years. Although silkworm silk has been studied extensively because of ready availability of the protein, lately the advancements in recombinant technology has made production of spider silk proteins increasingly available. Due to the characteristics like biocompatibility, biodegradability and mechanical strength, silk is highly desirable as a biomaterial for medical purpose. Along with this, techniques for functionalization, has further aided in the development of silk into highly sophisticated material for advanced applications. The main objective of this thesis has been to investigate novel strategies for functionalization of the recombinant spider silk protein Masp2. Two distinct approaches were used, chemical modification and genetic fusion. In the first modification, we created an infection responsive silk nanospheres by chemically grafting a thrombin sensitive peptide to the silk protein encapsulating antibiotic. These particles were then evaluated for in vitro infection responsive drug release and antimicrobial activity. From these assessments, we found that these particles can release the drug effectively in the presence of infection providing the evidence that these particles are enzyme responsive and can be used to formulate targeted drug release. In the second modification, spider silk was genetically modified with a heparin binding peptide to create a fusion protein which can prevent both thrombosis and infection simultaneously. This fusion protein was evaluated for its heparin binding ability and anticoagulant properties in its solution form. Furthermore, due to the similarity in structure of HBP with antimicrobial peptides, it is predicted that the fusion protein will also show antimicrobial property. After establishing these properties, next this fusion protein was utilized as a coating for hemodialysis catheter. Deposition of coating was evaluated after which anticoagulant and anti-infective properties of the protein as a coating material was investigated. This thesis provides evidence of successful production of a recombinant silk-based biopolymer that can be chemically and genetically embedded with a various functional motif to create a hybrid product for different applications.

Orientador: Priscylla Tatiana Chalfun Guimarães-Okamoto / Resumo: Cães com doença renal crônica (DRC) apresentam risco de eventos tromboembólicos, porém o mecanismo que leva à hipercoagulabilidade e ao risco na população de cães é desconhecido. O objetivo deste trabalho foi avaliar as possíveis tendências trombóticas e sua correlação com o estadiamento da DRC em cães. Trata-se de um estudo observacional transversal de casos-controle de cães atendidos no Hospital Veterinário da FMVZ – UNESP, com sinais clínicos compatíveis com DRC. Os animais incluídos neste estudo foram cães de tutores voluntários, com diagnóstico de DRC proteinúrica (n=19) e animais saudáveis (n=20). Foram avaliados hemograma, perfil bioquímico renal, hepático, lipídico e proteínas, urinálise e razão proteína/creatinina urinária, fibrinogênio, TP, TTPa, tromboelastometria (TEM) e o teste de geração de trombina (TGT). Não houve diferença na geração de trombina entre os grupos, refutando a hipótese de que a geração de trombina contribui para o estado de hipercoagulabilidade em cães com DRC e proteinúria. O fibrinogênio aumentado é o principal achado encontrado em cães com DRC, corroborando com os achados de hiercoagulabilidade na TEM. Estudos adicionais são necessários para explorar uma possível contribuição da trombogenicidade para as manifestações clínicas da DRC. / Abstract: Dogs with chronic kidney disease (CKD) are at risk thromboembolic events, but the mechanism leading to hypercoagulability and the population of dogs at risk are unknown. The aim of this study is to evaluate the possible thrombotic tendencies and their correlation with the staging of CKD in dogs. This is a observational cross-section study of client-owned dogs presented to Small Animal Clinical Service at the School of Veterinary Medicine and Animal Science of São Paulo State University, with clinical signs compatible with proteinuric CKD. The animals included this study were client-owned dogs with a diagnosis of proteinuric CKD (n=19) and healthy case-matched controls (n=20). Complete blood counts, renal, hepatic, lipidic and proteins serum biochemistry profile, urinalysis and urinary ratio protein/creatinine, fibrinogen, PT, aPTT, and thrombin generation test were evaluated. There was no difference in generation of thrombin between groups, refuting the hypothesis that thrombin generation is required for the state of hypercoagulability in dogs with CKD and proteinuria. Increased fibrinogen is the main finding found in dogs with CKD, corroborating with the findings of hypercoagulability in thromboelastometry. Studies are mandatory for the evaluation of thrombogenicity for clinical manifestations of DRC. / Doutor

A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Pharmacy Johannesburg 2001. i / The use of a low molecular weight heparin, enoxaparin was evaluated in the prevention and treatment of deep vein thrombosis. Patterns of use were analysed and measured against pre-determined criteria with a view to promoting optimal use and identifying those factors, which may contribute to safer use of the drug. / IT2018

No description available.

Decision analysis is a quantitative approach to decision-making that could bridge the gap between decisions based solely on evidence and the unique values and preferences of individual patients, a feature especially important when existing clinical evidence cannot support clear recommendations and there is a close balance between harms and benefits for the treatment options under consideration. Low molecular weight heparin for the prevention of venous thromboembolism (VTE) during pregnancy represents one such situation. The objective of this thesis is to explore the use of a decision analysis intervention for shared decision-making for thromboprophylaxis during pregnancy. This thesis begins with a scoping review that explores the ways in which decision analysis has been used to inform shared decision-making encounters, highlighting key challenges for implementing and evaluating this type of intervention. This is followed by a protocol that presents the methodology of an explanatory sequential mixed methods pilot study for the Decision Analysis in SHared decision making for Thromboprophylaxis during Pregnancy (DASH-TOP) tool. This tool was pilot tested through interviews of eligible women in Canada and Spain who were facing the treatment decision for the prevention of VTE in the antenatal period. While the tool was well received by patients, more effective ways of obtaining patient preferences and presenting the decision analysis results are required to enhance shared decision-making interactions. Finally, this thesis concludes with a reflection on the lessons learned from developing and evaluating a decision analysis intervention for shared decision-making. The insights from this research have informed the development of an integrated online shared decision-making tool for VTE in the antenatal period, which the DASH-TOP team plans to evaluate in a randomized controlled trial. It is hoped that this information will also provide guidance to researchers interested in developing or evaluating decision analysis interventions for other clinical decisions. / Dissertation / Doctor of Philosophy (PhD)

Thromboembolism (TE) significantly limits the usefulness and safety of blood-contacting devices such as hemodialysis catheters. Computer simulation of TE can provide understanding of the process and can facilitate the design of more effective devices. Previous work conducted at BYU successfully modeled TE in a simple, two-dimensional flow cell design by adding quantitative TE code to a commercial computational fluid dynamics (CFD) package, Fluent. This two-dimensional model predicted thrombus initiation and growth and adjusted flow to accommodate thrombus geometries, but was limited by computational power and unsophisticated meshing techniques. To build upon this work, and take advantage of BYU's new supercomputing system and improvements in automatic meshing software, development of a three-dimensional computational model of thrombosis in three hemodialysis catheters designs was undertaken. Development of the computer model was beset with challenges associated with limitations in both software and hardware, but those challenges were ultimately overcome as both software and hardware evolved. Eventually, the previous C-based Fluent model was ported to the Fortran-based STAR-CD model successfully. A computer geometry of a blood flow cell matching the geometry used with the previous two-dimensional model was created, and results for that geometry using the new computer compared favorably with the results from the previous model. Catheter geometries were created using computer-aided design (CAD) software and were meshed using auto-meshing software. CFD analysis identified potentially-troublesome flow regimes in the catheter designs that coincided with thrombotic regimes observed in preliminary experiments using those same catheter designs. The TE model is now ready for application to the catheter geometries and for rigorous testing (e.g., grid-independence, in-depth comparison with quantitative experiments, etc.).

A unique and novel method to study thromboembolism by direct observation was developed. High-definition videos of thrombus formation and embolization were successfully obtained in miniature flow cells using in-vitro, non-invasive, real-time techniques. Critical parameters of thromboembolism such as thrombus growth rate, thrombus growth direction, shear force on the thrombus at embolization, and adhesion strength of the thrombus to the foreign surface were determined. Thrombus growth was found predominantly in two locations: 1) in the flow recirculation zone just after the trailing edge of the small tubes (53%) and 2) at the leading edge of the small tubes (47%). In the small tubes, thrombus volume and shear force acting on the thrombus increased in a power-law like function of time. In the large tubes, thrombus volume and shear force acting on the thrombus increased in a linear like function of time. The slope of thrombus growth rate in the small tubes was significantly greater than that in the large tubes. Thrombus growth direction was also estimated by tracking the thrombus center of mass with respect to time and typically ranged from 15 to 35 degrees from the direction of flow. According to observations, embolization seems to occur via two possible mechanisms: 1) complete detachment of the thrombus by sliding off the foreign surface or 2) partial embolization of the thrombus by internal tearing. The estimated shear force on the thrombus at embolization was determined and was significantly greater in the small tubes than in the large tubes. The adhesion strengths of thrombi were calculated for the small tubes using the shear force at embolization and the estimated thrombus attachment area and ranged from 9.63 to 28.83 N/m2 (mean = 16.24 ± 2.59 N/m2 95% confidence), which was in good agreement with published results of platelet retention experiments. An experimental series demonstrated that the developed method could be used to study the effects of controlled variables on thromboembolism parameters. In that series, heparin concentration in blood, blood flow rate, and device design were studied one variable at a time to test their effects on thrombus growth parameters and adhesion strength. Because of the small number of data, these preliminary results were statistically insignificant but pointed the way for future studies.

Chemotherapy-associated thrombosis is a common complication in cancer patients. Cancer patients have a 5- to 7-fold increased risk for a thrombotic event compared to healthy individuals. While the overall risk for a thrombotic event in lung cancer patients is approximately 1.4%, the rates of thrombosis vary depending on the stage of the disease and the chemotherapeutic agents used. Activation of coagulation after initiation of chemotherapy has been reported in clinical studies. However, the mechanisms by which lung cancer chemotherapy agents modulate coagulation in lung cancer patients are not completely understood. The focus of this thesis is to investigate the mechanisms by which chemotherapy agents cisplatin, carboplatin, gemcitabine, and paclitaxel (in platinum-based combinations) induce procoagulant effects utilizing in vitro and in vivo approaches. First, we investigated the mechanisms by which lung cancer chemotherapy modulates cell-surface tissue factor (TF) activity on endothelial cells (HUVEC), monocytes, and non-small cell lung carcinoma (NSCLC) A549 cells. We observed that treatment of all three cell lines with platinum-based lung cancer chemotherapy increased cell surface TF activity. We found that the increased TF activity on chemotherapy-treated monocytes was due to increased phosphatidylserine (PS) exposure, whereas the increased TF activity on HUVEC and A549 cells was due to protein disulfide isomerase (PDI)-mediated decryption of TF. These studies demonstrate that lung cancer chemotherapy agents can exert procoagulant effects by increasing PS exposure and by inducing TF decryption on healthy and tumour cells. Next, we determined the effects of lung cancer chemotherapy on the generation of microparticles (MP) and the impact of MPs on thrombin generation. Our in vitro and in vivo studies demonstrate that lung cancer chemotherapy agents increase the generation of TF- and PS-positive MPs from tumour cells and that the MPs contribute to thrombin generation in a FVII-dependent manner. We also investigated the role of cell-free DNA (CFDNA) in mediating procoagulant effects induced by lung cancer chemotherapy agents. We found that lung cancer chemotherapy agents induce CFDNA release from healthy host neutrophils and that this leads to additional generation of thrombin by the intrinsic pathway of coagulation. Lastly, CFDNA levels have been shown to increase in cancer models through formation of neutrophil extracellular traps (NETs). Formation of NETs by NETosis, a process by which neutrophils release extracellular web-like structures composed of DNA, histones, and granular proteins, is dependent on histone citrullination by protein arginine deaminase-4 (PAD-4). In addition, PAD4 inhibition prevents NET formation. Therefore, we wanted to demonstrate that the neutrophil-derived CFDNA release induced by lung cancer chemotherapy is PAD4-dependent. Chemotherapy treatment of PAD4 knockout mice failed to increase CFDNA levels. Furthermore, chemotherapy-treatment did not increase thrombin generation in PAD4 knockout mice. This suggests that chemotherapy-induced CFDNA release occurs through NETosis. In conclusion, lung cancer chemotherapy leads to increased thrombin generation which occurs through increased TF decryption, MP generation, and CFDNA release. Therefore, lung cancer chemotherapy results in simultaneous activation of the extrinsic and intrinsic pathways of coagulation. These studies provide novel insight into the mechanisms of lung cancer chemotherapy-associated thrombosis. / Thesis / Doctor of Philosophy (PhD)