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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.
11

Hyperoxia impairs pro-angiogenic RNA production in preterm endothelial colony-forming cells

A. Ahern, Megan, P. Black, Claudine, J. Seedorf, Gregory, D. Baker, Christopher, P. Shepherd, Douglas January 2017 (has links)
Disruptions in the response of endothelial progenitor cells to changes in oxygen environment may present a possible mechanism behind multiple pediatric pulmonary disease models, such as bronchopulmonary dysplasia. Using high-throughput fixed single-cell protein and RNA imaging, we have created "stop-motion" movies of Thymosin. 4 (T beta 4) and Hypoxia Inducible Factor 1 alpha (HIF-1 alpha) protein expression and vascular endothelial growth factor (vegf) and endothelial nitric oxide synthase (eNOS) mRNA in human umbilical cord-derived endothelial colony-forming cells (ECFC). ECFC were grown in vitro under both room air and hyperoxia (50% O-2). We find elevated basal T beta 4 protein expression in ECFC derived from prematurely born infants versus full term infants. T beta 4 is a potent growth hormone that additionally acts as an actin sequestration protein and regulates the stability of HIF-1 alpha. This basal level increase of T beta 4 is associated with lower HIF1 alpha nuclear localization in preterm versus term ECFC upon exposure to hyperoxia. We find altered expression in the pro-angiogenic genes vegf and eNOS, two genes that HIF-1 alpha acts as a transcription factor for. This provides a potential link between a developmentally regulated protein and previously observed impaired function of preterm ECFC in response to hyperoxia.
12

Joint modeling of longitudinal and time to event data with application to tuberculosis research

Nigrini, Sharday January 2021 (has links)
Due to tuberculosis (TB) being one of the top ten diseases in Africa with the highest mortality rate, a crucial objective is to find the appropriate medication to cure patients and prevent people from contracting the disease. Since this statistic is not improving sufficiently, it is evident that there is a need for new anti-TB drugs. One of the main challenges in developing new and effective drugs for the treatment of TB is to identify the combinations of effective drugs when subsequent testing of patients in pivotal clinical trials are performed. During the early weeks of the treatment of TB, trials of the early bactericidal activity assess the decline in colony-forming unit (CFU) count of Mycobacterium TB in the sputum of patients containing smear-microscopy-positive pulmonary TB. A previously published dataset containing CFU counts of treated patients over 56 days is used to perform joint modeling of the nonlinear data over time and the patients’ sputum culture conversion (i.e., the time-to-event outcome). It is clear from the results obtained that there is an association between the longitudinal and time-to-event outcomes. / Mini Dissertation ( MSc (Advanced Data Analytics))--University of Pretoria, 2021. / South African Medical Research Council (SAMRC) / Statistics / MSc (Advanced Data Analytics) / Restricted
13

Mesenchyme homeobox 2 regulation of fetal endothelial progenitor cell function

Gohn, Cassandra Rebekah 19 June 2017 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / In the United States, 10% of pregnancies are complicated by diabetes mellitus (DM). Intrauterine DM exposure can have long-lasting implications for the fetus, including cardiovascular morbidity. Previously, we showed that fetal endothelial colony forming cells (ECFCs) from DM pregnancies have decreased vessel-forming ability and increased senescence. However, the molecular mechanisms responsible for this dysfunction remain largely unknown. The objective of this thesis was to understand how Mesenchyme Homeobox 2 (MEOX2) interacts with pathways that regulate cell cycle progression and migration, and how this interaction results in impaired vasculogenesis in DM exposed ECFCs. We tested the hypothesis that upregulated MEOX2 in DM-exposed ECFCs decreases network formation through impairments in senescence, cell cycle progression, migration, and adhesion. MEOX2 is a transcription factor which inhibits angiogenesis by upregulating cyclin dependent kinase inhibitors. Here, data show that nuclear MEOX2 is increased in DM-exposed ECFCs. Lentiviral-mediated overexpression of MEOX2 in control ECFCs increased network formation, altered cell cycle progression, increased senescence, and enhanced migration. In contrast, MEOX2-knockdown in DM-exposed ECFCs decreased network formation and migration, while cell cycle progression and senescence were unchanged. Adhesion and integrin expression defects were evaluated as mechanisms by which MEOX2 altered ECFC migration. While MEOX2-overexpression did not alter adhesion or cell surface integrin levels in control cells, MEOX2 overexpression in DM-exposed ECFCs resulted in an increase in α6 integrin surface expression. Similarly, MEOX2-knockdown in DM-exposed ECFCs did not alter adhesion, though did reduce α6 integrin surface expression and total cellular α6 mRNA and protein levels. Together, these data suggest that alterations in cell cycle progression and senescence are not responsible for the disrupted vasculogenesis of DM-exposed ECFCs. Importantly, these data suggest that altered migration may be a key mechanism involved and that altered cell surface levels of the α6 integrin may modify migratory capacity. Moreover, these data suggest that the α6 integrin may be a previously unrecognized transcriptional target of MEOX2. Ultimately, while initially believed to be maladaptive, these data suggest that increased nuclear MEOX2 in DM-exposed ECFCs may serve a protective role, enabling vessel formation despite exposure to a DM intrauterine environment.
14

MECHANISMS OF OZONE TOXICITY

SOO, CAROL 22 May 2002 (has links)
No description available.
15

Liten tuva stjälper ofta stort lass : Bakteriell kontamination över tid av operationsinstrument vid öppen neurokirurgi / A small tuft often overturns a big load : Bacterial contamination over time on surgical instruments used in open neurosurgery

Ekman, Jakob, Bernroth, Benjamin January 2016 (has links)
Bakgrund: Postoperativa sårinfektioner orsakar lidande för den drabbade patienten och kostnader för patienten, vården och samhället. Intraoperativ kontamination av operationsinstrumenten är en av källorna till dessa infektioner. Operationssjuksköterskan är ansvarig för aseptiken och operationsinstrumenten.   Syfte: Syftet med denna pilotstudie var att mäta graden av bakteriell kontamination över tid på operationsinstrument som används vid öppen neurokirurgi samt observera utvalda källor till kontamination under samma tid. Metod: Denna studie designades som en kvantitativ icke-experimentell observationsstudie. Datainsamlingen skedde under hösten 2015 och bestod av omhändertagandet av specifika instrument som använts av operatören under operationen efter förutbestämd åtgången knivtid. Bakterieodlingar på dessa instrument skedde sedan på laboratorium enligt en förutbestämd metod och graden av kontamination mättes genom observation av mängden colony forming units (CFU). Resultaten presenteras i form av förändringar av mängden CFU. Resultat: Fem operationer observerades och tio odlingar utfördes på tio instrument. Totalt tio CFU registrerades under samtliga observationer. Ingen signifikant ökning av antal CFU kunde observeras från en till två timmars knivtid (P=0,156). Antal dörröppningar ökade från 3,4 till 9,0 och antal personer på operationssalen ökade från 5,4 till 5,8. Slutsats: Trots det ringa antal observationer som ingick i denna studie tyder resultaten på god aseptik och minimal bakteriell kontamination på operationsinstrumenten under operationens två första timmar. Ytterligare forskning med längre observationer, fler observationer och observationer kring annan typ av kirurgi behövs. / Background: Post-operative surgical site infections (SSI) cause suffering for the afflicted patient and is a great cost for the patient, the health care system and society. Intra-operative contamination of surgical instruments is one of the sources of these infections. The operating room nurse is responsible for preventing infections. Purpose: The purpose of this pilot-study was to measure the degree of bacterial contamination over time on surgical instruments used in open neurosurgery as well as to observe specific sources of contamination during this time. Method: The design was a quantitative nonexperimental observational study. The data collection took place during autumn 2015 and consisted of the sampling of specific instruments used by the surgeon during surgery after preset elapsed operating times. Bacterial culturing on these instruments was then carried out at a laboratory according to a preset routine and the degree of contamination was measured by observing the amount of colony forming units (CFU). The results are presented as changes in CFU. Results: Five operations were observed and ten bacterial culturings were conducted on ten instruments. A total of ten CFU was registered during all observations. No significant increase in the number of CFU could be observed from one to two hours of elapsed surgery (P=0,156). The amount of door openings increased from 3,4 to 9,0 and the number of personnel in the operating room increased from 5,4 to 5,8. Conclusion: Despite the small number of observations included in this study the results indicate good aseptics and minimal bacterial contamination on the surgical instruments during the first two hours of surgery. Further research with longer observations, more observations and observations on other forms of surgery is needed.
16

Epithelial and vascular progenitors in the developing lung: Newer insights and therapeutic implications

Stanislaus Alphonse, Anthuvan Rajesh Unknown Date
No description available.
17

Role of Circulating Peripheral Blood-Derived Endothelial Colony-Forming Cells in Patients with Proliferative Diabetic Retinopathy

Tan, Kevin S. 13 May 2009 (has links)
No description available.
18

Abundance, genetic diversity and persistence of Metarhizium spp. fungi from soil of strawberry crops and their potential as biological control agents against the two-spotted spider mite Tetranychus urticae / Abundância, diversidade genética e persistência de fungos Metarhizium spp. isolados de solos de morangueiro e seu potencial como agentes de controle biológico do ácaro rajado, Tetranychus urticae

Castro, Thiago Rodrigues de 20 April 2016 (has links)
The growing demand for strawberries has imposed challenges, especially regarding the control of pests. Many farmers report problems with reduced chemical control efficiency, probably due to selection of resistant populations of insects and mites. An alternative is the use of biological control using pathogenic fungi as a tool in integrated pest management. Metarhizium spp. (Hypocreales: Clavicipitaceae) are generalist entomopathogenic fungi with worldwide distribution and can cause diseases in a large number of hosts. Many studies on the development of Metarhizium as a biological control agent were performed, but this bulk of knowledge is in remarkable contrast to the lack of research on the fundamental ecology of Metarhizium in agroecosystems. This thesis aimed to evaluate the establishment, persistence and dispersal of these entomopathogenic fungi in strawberry crop soil in Inconfidentes, Minas Gerais, Brazil; and to study the diversity and abundance of species of Metarhizium isolated from organic and conventional strawberry crop soils, and the field margins in Brazil and Denmark. The effectiveness of new species of Metarhizium recently found in Brazil, was evaluated against two spotted spider mite, Tetranychus urticae. Applied isolates of M. anisopliae (ESALQ1037) and M. robertsii (ESALQ1426) were able to persist for up to 12 months after the application within the soil, and disperse to other plots and colonize the rhizosphere of strawberry plants. In the plots where ESALQ1037 and ESALQ1426 were applied, 25% and 87.5% of the isolates recovered after 12 months consisted of the same isolates inoculated. A new taxonomically unassigned lineage, referred to as Metarhizium sp. Indet. 5 in this study, was found in strawberry crop margins. The dominant species of Metarhizium in Brazil and Denmark was Metarhizium robertsii and M. brunneum respectively. Further, Metarhizium pemphigi was first detected in Denmark in this study. Soil in organically grown strawberries harbored a more diverse population of Metarhizium spp. compared with conventionally grown strawberries. These studies showed for the first time the potential of new species of Metarhizium as spider mite biological control agents, the lowest median lethal time (LT50 = 4 ± 0.17 days) was observed in mites treated with the isolate ESALQ1638 of Metarhizium sp. indet. 1. The best isolates were ESALQPL63 of B. bassiana, ESALQ1608 and ESALQ1638 of Metarhizium sp. indet. 1 and ESALQ3069 and ESALQ3222 of M. pingshaense based on the survival curve, total mortality, percentage of sporulated cadavers and LT50. Knowledge of the diversity of Metarhizium spp. and persistence in strawberry soil generated in this study may be useful in developing conservation strategies and maximize the natural biological pest control. / A crescente demanda por morangos vem impondo desafios, especialmente quanto ao controle das pragas. Muitos agricultores relatam problemas com a redução da eficiência do controle químico, provavelmente devido à seleção de populações resistentes de insetos e ácaros. Uma alternativa é o uso de controle biológico com fungos entomopatogênicos como ferramenta dentro do manejo integrado de pragas. Metarhizium spp. (Hypocreales: Clavicipitaceae), são fungos entomopatogênicos generalistas com distribuição cosmopolita e que podem causar doenças em um grande número de hospedeiros. Muitos estudos sobre o desenvolvimento de Metarhizium como agente de controle biológico foram realizados, mas este leque de conhecimento está em contraste com a notável falta de investigação sobre a ecologia de Metarhizium nos agroecossistemas. Esta tese teve como objetivo avaliar o estabelecimento, persistência e dispersão destes fungos entomopatogênicos em solo de morangueiro em Inconfidentes, Minas Gerais, Brasil; bem como estudar a diversidade e abundância de espécies de Metarhizium isolados do solo de cultivos orgânico e convencional de morangueiro, e das margens das plantações no Brasil e Dinamarca. A eficácia de novas espécies de Metarhizium, encontradas recentemente no Brasil, foi avaliada contra o ácaro rajado, Tetranychus urticae. Os isolados inoculados de M. anisopliae (ESALQ1037) e M. robertsii (ESALQ1426) foram capazes de persistir por até 12 meses após a aplicação no solo, além de dispersar para outras parcelas e colonizar a rizosfera dos morangueiros. Nas parcelas onde ESALQ1037 e ESALQ1426 foram aplicados, 25% e 87,5% dos isolados recuperados após 12 meses consistiam dos mesmos isolados inoculados. Uma nova linhagem não taxonomicamente identificada, referida neste trabalho como Metarhizium sp. Indet. 5, foi encontrada nas margens de morangueiros cultivados. A espécie dominante de Metarhizium no Brasil e Dinamarca foi Metarhizium robertsii e M. brunneum, respectivamente. Além disso, Metarhizium pemphigi foi detectado pela primeira vez na Dinamarca neste estudo. Solos de cultivo orgânico de morangueiro em geral apresentaram uma diversidade maior de Metarhizium do que solos de cultivos convencionais. Estes estudos revelaram pela primeira vez o potencial de novas espécies de Metarhizium como agentes de controle biológico do ácaro rajado, sendo o menor tempo letal mediano (TL50= 4 ± 0.17 dias) observado em ácaros tratados com o isolado ESALQ1638 de Metarhizium sp. indet. 1. Os melhores isolados foram ESALQPL63 de B. bassiana, ESALQ1608 e ESALQ1638 de Metarhizium sp. indet. 1 e ESALQ3069 e ESALQ3222 de M. pingshaense baseado na curva de sobrevivência, mortalidade total, porcentagem de cadáveres esporulados e TL50. O conhecimento da diversidade de Metarhizium spp. e persistência em solos de morango, gerados neste estudo, poderão ser úteis no desenvolvimento de estratégias de conservação e maximizar o controle biológico natural de pragas.
19

Influência de fatores de crescimento pró-angiogênicos na manutenção das características de células progenitoras mesenquimais derivadas do tecido adiposo / Influence of pro-angiogenic growth factors in the maintenance of mesenchymal stem cells characteristics derived from adipose tissue

Pimentel, Thaís Valéria Costa de Andrade 16 October 2015 (has links)
A manutenção do estado progenitor durante o cultivo de células mesenquimais progenitoras derivadas do tecido adiposo (MSCs-TA), caracterizado pelo potencial de diferenciação e da capacidade de autorrenovação, é atualmente um dos maiores desafios da terapia celular. Sabendo da influência da angiogênese no desenvolvimento de tecidos de origem mesenquimal, avaliamos se um ambiente pro-angiogênico mimetizado em cultura forneceria condições para manutenção de um estado progenitor durante o processo de expansão celular. Utilizando como modelo de um ambiente pró-angiogênico o cultivo no meio EGM-2, o qual é suplementado pelos fatores de crescimento EGF, FGF-2, IGF e VEGF, nós demonstramos que a presença de tais fatores pró-angiogênicos é fundamental para a manutenção do estado progenitor de MSCs-TA em cultura. Verificamos que a presença de tais fatores de crescimento possibilitaram às MSCs-TA apresentarem um alto potencial de diferenciação adipogênico e osteogênico em comparação ao meio convencional DMEM/F12 e ao meio EBM, ausente de fatores. Além disso, o cultivo na presença de fatores pró-angiogênicos aumentou o potencial clonogênico das MSCs-TA, ao mesmo tempo em que aumentou a capacidade proliferativa destas células. Dentre os fatores de crescimento, EGF e FGF-2 foram responsáveis pelos efeitos mais robustos. Ao mesmo tempo, células cultivadas nas presença destas citocinas foram capazes de manter a morfologia fibroblastóide e apresentaram alta expressão do fator de pluripotência Klf-4. Em concordância com estes achados, o transplante subcutâneo de MSCs-TA cultivadas nestas condições mostrou que aquelas mantidas em EGM-2 geram um tecido semelhante ao tecido formado pela fração estromal vascular não cultivada. Estes resultados reforçam o papel do ambiente pró-angiogênico na manutenção do estado progenitor de MSCs-TA, e que tal estado foi proporcionado pela ação dos fatores de crescimento pró-angiogênicos EGF, FGF-2, IGF e VEGF nas células em cultivo, com destaque para as citocinas EGF e FGF-2. Em conclusão, o uso do ambiente pró-angiogênico no cultivo de MSCs-TA mostrou-se como uma abordagem promissora para a manutenção do estado progenitor destas células in vitro. / The maintenance of the progenitor state in the culture of adipose tissue derived- mesenchymal progenitor cell (TA-MSCs), characterized by the differentiation potential and self-renewal capability, is currently one of the major challenges of cell therapy. The information that the angiogenesis influences the development of mesenchymal tissues, has led us to evaluate how a pro-angiogenic environment mimicked in culture would provide conditions for maintaining a progenitor state during the cell expansion process. We designe a model for a pro-angiogenic environment in which cells grown in EGM-2 supplemented with the following growth factors: EGF, FGF-2, IGF and VEGF, and demonstrated that the presence of such pro-angiogenic growth factors was crucial for maintenance of the progenitor of AT-MSCs in culture. We observed that the presence of such growth factors allowed to AT-MSCs a high potential of adipogenic and osteogenic differentiation compared to conventional DMEM/F12 medium and the EBM medium, in the absence of the factors. Furthermore, the culture in presence of pro-angiogenic growth factors increased the clonogenic potential of AT-MSCs and increased the proliferative capability of these cells. Among the growth factors, EGF and FGF-2 were responsible for most robust effects. At the same time, cells cultured in the presence of these cytokines were able to maintaining the fibroblastoid morphology and presented high expression levels of Klf-4 pluripotency factor. In agreement with these observations, the subcutaneous transplantation of AT-MSCs cultured under these conditions showed that those cells kept in EGM-2 generated a tissue-like to tissue formed by the stromal vascular fraction uncultivated. These results reinforce the role of the pro-angiogenic environment in the maintenance of the progenitor state of AT-MSCs, and that such a state was provided by the action of the pro-angiogenic growth factors EGF, FGF-2, IGF and VEGF in cultured cells, highlighting EGF and FGF-2 cytokines. In conclusion, we showed that the use of a pro-angiogenic environment in AT-MSCs culture is a promising approach to the maintain the progenitor state of these cells in vitro.
20

Comparação entre o crescimento de Unidades Formadoras de Colônias (UFC) de Staphylococcus spp. e Klebsiella pneumoniae e a sensibilidade destas cepas ao processo de pasteurização lenta / Comparison between the growth of Colony Form Units of Staphylococcus spp. and Klebsiella pneumoniae and the sensibility of these microorganisms to the process of slow pasteurization

Gisele Dias de Freitas 15 February 2008 (has links)
Introdução: O leite pode ser considerado um dos alimentos mais completos por apresentar alto teor de proteínas e sais minerais, porém, também é considerado excelente meio de cultura para microrganismos. Objetivos: Identificar o número de UFC de Staphylococcus spp. e Klebsiella pneumoniae, cultivados isoladamente ou em associação, em leite integral estéril, a 6 oC, 27 oC e 37 oC e descrever a curva de morte térmica, quando submetidas ao processo de pasteurização lenta isoladamente ou em associação. Material e Métodos: Avaliação através da contagem das UFC, do comportamento de Staphylococcus spp. e K. pneumoniae, isoladas de tanque de refrigeração de leite, submetidas a temperaturas que simulam o leite em condições de refrigeração (6 °C), condições ambientais (25 °C) e na temperatura ideal de crescimento de patógenos mesófilos (36°C). Avaliação da sensibilidade de Staphylococcus spp. e K. pneumoniae isoladas e em associações ao processo de pasteurização lenta. Resultados: Na escala 1 de Mac Farland a média de UFC de K. pneumoniae foi maior que a de Staphylococcus spp. A 6 °C as bactérias no leite, isoladas ou em associação crescem na mesma velocidade. A 25 °C a K. pneumoniae cresce mais que o Staphylococcus spp. A 25 °C K. pneumoniae associada ao Staphylococcus spp. cresce mais do que quando encontra-se isolada. A 36 °C K. pneumoniae associada ao Staphylococcus spp. cresce mais do que quando encontra-se isolada e ainda mais que a 25 °C. A pasteurização lenta foi efetiva, pois reduziu em no mínimo 90% as UFC no leite após 30 minutos a 65 °C. Conclusão: a medida que aumenta a temperatura, até 36 °C, a Klebsiella pneumoniae apresenta crescimento superior ao Staphylococcus spp., a contaminação de leite por Klebsiella pneumoniae (contaminação ambiental) irá influenciar mais na qualidade do produto final, comparando-se à contaminação por Staphylococcus spp., oriundo de mastite e a interação de microrganismos altera a morte dos mesmos, recomendando-se que novos estudos sejam realizados para que se entenda melhor esse processo. / Introduction: The milk can be considered one of the most complete food for its high contents of protein and minerals, but also it is considered an excellent medium of culture for microorganisms. Objective: To identify the number of the Colony Forming Units of Staphylococcus spp. and Klebsiella pneumoniae, in integral sterile milk, at different temperatures (6ºC, 27ºC e 37ºC) and to describe a thermal curve death, when submitted to the process of slow pasteurization isolated or in association. Materials and methods: Evaluation by counting of the colony forming units and the behavior of the Staphylococcus spp. and Klebsiella pneumoniae, isolated and in association occurred in the cooling tank, submitted to temperatures that simulate the conditions of milk in cooling (6ºC), environmental condition (25ºC) and the optimal temperature for the growth of microorganisms (36ºC). Evaluation of the sensibility of Staphylococcus spp. and Klebsiella pneumoniae isolated and in association during the pasteurization process. Results: In Scale 1 of Mac Farland the average of the colony form units of the K. pneumoniae was greater than the colony of Staphylococcus spp. At 6ºC the microorganisms in the milk isolated or in association grew at the same speed. At 25ºC K. pneumoniae associated with Staphylococcus spp. grew more than when they were isolated. At 36ºC K. pneumoniae associated with Staphylococcus spp. grew more then when it was isolated and more than at 25ºC. So we can conclude that the slow pasteurization was effective, because it has reduced at least 90% of the colony form unity in the milk after 30 minutes at 65ºC. Conclusion: By raising the temperature up to 36ºC, a Klebsiella pneumoniae had a superior growth when compared with Staphylococcus spp.; the contamination of milk by Klebsiella pneumoniae (environmental contamination) influences the most the quality of the final product when compared to the contamination by Staphylococcus spp. from mastitis, we can also conclude that the interaction of microorganisms modify the death rate of them. New studies and researches are recommended to a deeper and better comprehension of this process.

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