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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.
231

A framework for rapid problem assessment in healthcare delivery systems

Singprasong, Rachanee January 2012 (has links)
Problems in healthcare are difficult to comprehend due to complexity, involvement of multiple stakeholders in decision making and fragmented structure of delivery systems. Major Problem Structuring Methods (PSMs) have been used to aid problem understanding which, in principle, can provide greater clarity to strategic problems and engage diverse decision makers using transparent representation that capture differing perceptions of problems. In reality, PSMs can be difficult in accurately representing problems, limited in highlighting improvement opportunities due to non-intuitive visual representations and requirements for facilitators and stakeholders to be experts in tools used. This research aims to address this gap by developing a framework, taking into account characteristics of healthcare delivery systems, advantages and limitations of PSMs with an aim of providing accurate and holistic representation of delivery workflow, so as to promote problem understanding in a rapid manner. The framework, termed CARE, first establishes nature of problem and a commonly agreed problem statement along with an understanding of stakeholder involvement and operating regulations. It then sets specific guidelines for data collection, representation, verification and validation from stakeholders and provides methodology for data analysis which allows facilitator insight into possible flaws in workflow. A case study approach is used to test effectiveness of CARE across two different healthcare settings, each involving a different nature of problem. Implementation of CARE leads to improved participation and ownership amongst stakeholders, ease of facilitation during individual or multidisciplinary meetings, intuitive and informative representation of workflow, minimized time and effort for implementation and minimized dependencies on learning new tools and terminologies. A post mortem indicates the positive impact of CARE on services rendered to the patients, leading to an increase in patient satisfaction and workflow efficiencies. The research concludes by noting the contributions and lessons learnt from this research for healthcare practitioners and possible future work.
232

Polymerní nosiče pro nukleární medicínu / Polymer carriers for nuclear medicine

Sedláček, Ondřej January 2015 (has links)
In the thesis, we developed and studied a novel polymer delivery system for the DNA-intercalator bearing radioisotope iodine-125. Auger electrons emitting radioisotopes (such as iodine-125 or indium-111) are a potentially effective cancer treatment. Their use as an effective cancer therapy requires that they will be transported within close proximity of DNA, where they induce double-strand breaks leading to the cell death. This type of therapy may be even more beneficial when associated with drug delivery systems. The DNA intercalators proved to be effective carriers for the delivery of Auger electron emitters into DNA. Therefore, the new radioiodinated DNA-intercalating ellipticinium derivatives were synthesized and characterized. These compounds were linked to N-(2-hydroxypropyl) methacrylamide copolymer with narrow molecular weight distribution via acid-sensitive hydrazone linker. The structure of the linker plays a crucial role in the biological effectivity of the delivery system, so it was optimized to be stable at pH 7.4 (representing the pH of blood plasma), whereas in slightly acidic pH in endosomes after the cell internalization, the radioiodine-containing biologically active intercalator is rapidly released from its polymer carrier. The intercalating ability of the active compound was...
233

Development of spray-dried polycaprolactone-drug loaded nanoparticles towards improving current HIV chemotherapy

29 July 2013 (has links)
M.Sc. (Chemistry) / Human immunodeficiency virus (HIV) is continuously rewriting medical history as one of the diseases affecting humankind. Current treatments available for HIV, namely antiretrovirals (ARVs), do not completely eradicate the virus from the body, leading to life time commitment. Many ARVs suffer from high toxicities and unpleasant side effects; as a result many patients do not adhere to the treatment. Nanoparticles (NPs) used as drug delivery systems (DDS) hold tremendous potential, since they can easily protect the drug from external environment and enter the human cells to deliver drugs. Therefore, the main objective of this work was to load two ARVs, namely lamivudine (LAM) and efavirenz (EFV), into a biodegradable, biocompatible poly(epsilon-caprolactone) (PCL) polymer based NPs. LAM is a hydrophilic drug suffering from low half life of 5 to 7 hours and many unpleasant side effects. EFV is a hydrophobic drug suffering from low aqueous solubility (4 μg/ml), which leads to a limited oral absorption and low bioavailability (40-45%).
234

Design and evaluation of a gastroretentive device for drugs with a narrow absorption window

Moonisami, Sarashnee 03 November 2009 (has links)
M.Sc. (Pharmaceutical Affairs), Faculty of Health Sciences, University of the Witwatersrand, 2009
235

Desenvolvimento e caracterização de sistemas nanoestruturados para potencial administração nasal de zidovudina /

Carvalho, Flávia Chiva. January 2009 (has links)
Resumo: A zidovudina (AZT) é o fármaco antiretroviral mais utilizado no tratamento da AIDS, porém possui baixa biodisponibilidade, pois sofre intenso metabolismo hepático. Para alcançar concentrações plasmáticas efetivas são requeridas doses altas e freqüentes, as quais podem chegar a níveis tóxicos. A via nasal tem sido proposta como uma rota alternativa para administração de fármacos que sofrem metabolismo pré-sistêmico, pois favorece a absorção direta para circulação sanguínea; porém, ela possui mecanismos de depuração mucociliar, os quais podem eliminar rapidamente a formulação da cavidade nasal. Sistemas de liberação mucoadesivos podem promover o contato prolongado entre a formulação e os sítios de absorção da cavidade nasal, retardando a depuração mucociliar. Alguns sistemas estabilizados por tensoativos, capazes de formar diferentes estruturas liotrópicas líquido cristalinas, têm sido propostos para aumentar o tempo de contato de formulações com as mucosas. Estes sistemas, ao entrar em contato com os fluidos aquosos que compõem o muco, se ordenam em cristais líquidos (CLs), formando uma matriz de liberação do fármaco. O objetivo deste trabalho foi desenvolver sistemas capazes de formar CLs, como potenciais sistemas mucoadesivos para administração intranasal do AZT. A caracterização por microscopia de luz polarizada e SAXS mostrou que microemulsões (MEs) formadas por AC205/ácido oléico/água formam CLs com a adição tanto de água como de fluído nasal simulado (FNS). As MEs foram capazes de incorporar cerca de 50 mg.g-1 de AZT. A mucoadesão foi avaliada por ensaios de reologia oscilatória, em que a adição de fase aquosa aumentou os módulos elásticos dos sistemas, e pela medida da força para remover as formulações a partir de um disco de mucina, obtidas através de um analisador de textura. Ensaios de liberação in vitro em... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Zidovudine (AZT) is the most widely used drug in AIDS treatment; however, AZT shows low oral bioavailability, since it suffers extensive hepatic metabolism. In order to maintain therapeutic levels, large doses have to be given frequently, which may reach toxic levels. The nasal route has been exploited as an alternative route of drugs that suffer first pass metabolism, as it ensures the direct drug absorption to blood circulation; however, the nasal route has mucociliary clearance mechanisms which can quickly remove the formulation of the nasal cavity. Mucoadhesive drug delivery systems can improve residence time of formulation in the nasal cavity absorption sites, delaying mucociliary clearance. Some surfactants systems which are able to form different liotropic liquid crystalline structures have been explored as a strategy to increase formulation residence time on the mucosa. When these systems are placed in physiologic aqueous environment, they can form a drug delivery matrix. The aim of this work was to develop systems capable of forming CLs as potential intranasal AZT mucoadhesive systems. The polarized light microscopy and SAXS characterization showed that microemulsions (MEs) composed by AC205/oleic acid/water form CLs with the addition of either water or simulated nasal fluid (FNS). The MEs were able to incorporate about 50 mg.g-1 of AZT. The mucoadhesion was evaluated both by oscillatory rheology, in which aqueous phase addition increased the elastic modulus of the systems, and by measurement of the necessary force to remove the formulations from mucin disc, obtained through texture analyzer. In vitro Franz' Cell drug release assay showed, according to the Weibull model, that phase transition sustained AZT release. These results suggest that the systems in hand have great potential for nasal AZT administration. / Orientador: Maria Palmira Daflon Gremião / Coorientador: Victor Hugo Vitorino Sarmento / Banca: Maria Palmira Daflon Gremião / Banca: Marcela Longhi / Banca: Rosângela Itri / Mestre
236

Potencialidade do uso de sistemas lipossomais contendo ácido ursólico como estratégia para otimização do tratamento da doença de Chagas / Potencial use of liposomal systems containing ursolic acid for the treatment optimization of Chagas Disease

Trevisani, Mayara Garcia 18 August 2014 (has links)
A doença de Chagas causada pelo Trypanosoma cruzi representa um grave problema de saúde pública na América Latina e cada vez mais em todo o mundo, afetando principalmente regiões de baixo poder aquisitivo, e por isso negligenciada pela indústria farmacêutica. Atualmente apenas um fármaco está disponível, o benzonidazol, o qual apresenta eficácia limitada e está associado a diversos efeitos colaterais. Estudos recentes demonstraram atividade tripanocida do ácido ursólico, entretanto sua utilização é limitada pela alta hidrofobicidade, sendo o uso dos nanocarreadores lipossomais reconhecido como uma estratégia promissora para solucionar tal limitação, além de serem sistemas altamente versáteis e biocompatíveis. Neste trabalho, foram desenvolvidos lipossomas de fosfatidilcolina e colesterol contendo ácido ursólico pela técnica da evaporação do solvente e hidratação do filme lipídico seguida de sonicação, permitindo a obtenção de vesículas unilamelares e com baixa polidispersividade. A partir da avaliação preliminar da estabilidade das dispersões, a adição do colesterol na razão molar 10:1 fosfatidilcolina:colesterol foi essencial para a manutenção do conteúdo encapsulado quando a formulação foi estocada em temperatura ambiente e melhor retenção do conteúdo a 4°C (90%). Após a liofilização o emprego de sucrose na razão molar 1:10 lipídeo:açúcar, a formulação manteve o tamanho e distribuição de tamanho e impediu a agregação das vesículas. A formulação obtida foi caracterizada por microscopia eletrônica de transmissão, apresentando diâmetro entre 100 e 120 nm, também observado pelo espalhamento dinâmico da luz. As análises por espectroscopia no infravermelho e calorimetria exploratória diferencial demonstraram uma forte interação do fármaco com a membrana fosfolipídica por interações de hidrogênio, assim como uma menor mobilidade das cadeias lipídicas e formação de uma matriz vítrea a qual foi responsável pela efetiva crioproteção das vesículas. Estudo in vitro do perfil de liberação do fármaco a partir dos lipossomas pela técnica da diálise resultou em alta retenção do conteúdo encapsulado e uma liberação sustentada deste. A partir de ensaio biológico in vitro empregando azul de trypan, a formulação liofilizada contendo ácido ursólico se mostrou segura até a concentração em que seria necessária para carrear 32 ?M do fármaco, considerando a linhagem de mamíferos LLC-MK2. Em relação à atividade tripanocida em linhagem da cepa CL da forma epimastigota empregando MTT, o lipossoma contendo o fármaco foi capaz de causar morte celular do parasita em 100%, considerando-se um possível efeito sinérgico do ácido ursólico e o colesterol, cuja seletividade à membrana do parasita tem sido recentemente demonstrada. Contudo apenas a formulação contendo o ácido ursólico apresentou índice de seletividade aceitável, o que está relacionado com o efeito citoprotetor do ácido ursólico. / Chagas disease caused by Trypanosoma cruzi is a serious public health problem in Latin America and is an increasing disease around the world, mainly affecting regions with low purchasing power, and therefore Chagas disease is considered neglected by the pharmaceutical industry. Today, only one product is available, benznidazole, which has limited efficacy and is associated with several side effects. Recent studies have shown trypanocidal activity of ursolic acid, however its use is limited by the high hydrophobicity. The use of liposomal nanocarriers is recognized as a promising strategy to address this limitation and they are highly versatile and biocompatible systems. In this study, ursolic acid loaded phosphatidylcholine and cholesterol liposomes were developed using the solvent evaporation and lipid film hydration technique followed by sonication, allowing unilamellar vesicles formation with low polydispersity. From the preliminary assessment of the dispersion stability, the addition of cholesterol allowed the encapsulation efficiency maintenance when the formulation was stored at room temperature and better drug retention at 4°C (90%). After lyophilization employing sucrose 1:10 lipid:sugar molar ratio, the formulation manteined the size and size distribution and vesicle aggregation was prevented. The formulation obtained was characterized by transmission electron microscopy, with diameter between 100 and 120 nm, also observed by dynamic light scattering. The analysis by infrared spectroscopy and differential scanning calorimetry showed a strong hydrogen interaction between ursolic acid and the phospholipid membrane, as well as a lower mobility of the lipid chains and glassy matrix formation which was responsible for the effective cryoprotection. In vitro drug release profile from liposomes by dialysis technique resulted in high retention of the encapsulated content and a sustained release. From in vitro biological assay using trypan blue, the ursolic acid loaded lyophilized liposomes proved to be safe up to a concentration that would be required to carry 32 ?M of the drug, considering the LLC-MK2 mammalians cell line. Regarding the trypanocidal activity of epimastigotes CL strain by MTT technique, the ursolic acid loaded liposomes showed greater efficacy than blank liposome able to causing 100% of parasite cell death, considering a possible synergism effect of ursolic acid and cholesterol, whose selectivity to the parasite membrane has been recently demonstrated. However, only the formulation containing ursolic acid showed acceptable selectivity index, which is related to the ursolic acid cytoprotective effect.
237

Dendrímeros: uma estratégia para a veiculação de um fármaco anticâncer / Dendrimers: a strategy for an anticancer drug delivery

Topan, José Fernando 16 September 2016 (has links)
O câncer de mama constitui o segundo tipo de câncer mais frequente no mundo e o mais comum entre as mulheres, devido ao seu alto grau de malignidade. A quimioterapia é utilizada no tratamento de câncer de mama com presença de metástase, dentre os fármacos mais utilizados está o paclitaxel, que atua na desestabilização dos microtúbulos na divisão celular, levando a célula neoplásica a apoptose, porém, o paclitaxel é uma molécula extremamente lipofílica, solubilizada em Cremophor® EL, um tensoativo altamente tóxico utilizado na formulação comercial. O objetivo deste trabalho foi desenvolver complexos dendriméricos com paclitaxel para a otimização da terapia do câncer de mama. Para a quantificação do paclitaxel nos sistemas de liberação desenvolvidos foram validados métodos analíticos por espectrofotometria UV-Vis e por cromatografia líquida de alta eficiência. Os métodos foram seletivos, linear, precisos e exatos. Para a obtenção de uma formulação concentrada os complexos foram liofilizados. O complexo PAMAM-G4-NH2-Paclitaxel foi obtido em diversos meios reacionais, com diferentes faixas de pH, sendo o tampão Hepes, pH 7,4, e água; os meios que obtiveram melhores resultados de complexação, posteriormente foram analisados por DLS e NTA, com diâmetro médio de partícula em 160 nm e potencial zeta catiônico. A caracterização do complexo obtido foi realizada por análises de espectrofotometria no infravermelho e ressonância magnética nuclear. O estudo in vitro de liberação do paclitaxel a partir dos complexos dendriméricos foi realizado utilizando membrana de acetato de celulose e quantificação por CLAE. O perfil de liberação demonstrou que após 156 horas, no máximo 35% do fármaco foi liberado. A liberação lenta representa uma vantagem para o tratamento de tumores sólidos, pois idealmente o sistema de liberação deve manter o fármaco encapsulado durante a circulação sanguínea e liberá-lo uma vez acumulado passivamente no sítio tumoral. A citotoxicidade foi avaliada na linhagem tumoral 4T1, através do ensaio do MTT. O complexo PAMAM-G4-NH2-Paclitaxel apresentou citotoxicidade 5 vezes maior que a formulação comercial. Na avaliação antitumoral in vivo do complexo, foram avaliados a curva do crescimento tumoral, o registro de peso, a sobrevivência dos animais e a proliferação celular com o anticorpo ki 67. O complexo dendrimérico teve efeito estatisticamente significativo na redução do volume tumoral e, através da análise de imunohistoquimica foi confirmada a redução da proliferação celular. Portanto, o complexo PAMAM-G4-NH2-Paclitaxel pode representar uma estratégia promissora para o tratamento de câncer de mama e posteriormente deverá ser avaliada por meio de estudos clínicos. / Breast cancer is the second most common type of cancer worldwide and the most common among women, due to its high degree of malignancy. Chemotherapy is used to treat breast cancer metastasis, among the most widely used drugs are paclitaxel, which operates in the microtubules destabilization in cell division, resulting in neoplastic cell apoptosis, however, paclitaxel is a highly lipophilic molecule which is solubilized in Cremophor® EL, a highly toxic surfactant used in the commercial formulation. The aim of this study was to develop dendrimeric complex with paclitaxel for the optimization of breast cancer therapy. To quantify the paclitaxel in the developed delivery systems, the analytical method was validated by UV-Vis spectrophotometry and high-performance liquid chromatography. The methods were selective, linear, accurate and precise. To obtain a concentrated formulation, the complexes were lyophilized. The PAMAM-G4-NH2-paclitaxel complex was obtained in various reaction media with different pH ranges, with the HEPES buffer, pH 7.4, and water. The media with obtained the best complexation were subsequently analyzed by DLS and NTA, and the mean particle diameter was 160 nm with a cationic zeta potential. The characterization of the obtained complex was performed by infrared and nuclear magnetic resonance spectrophotometric analysis. The in vitro release study of paclitaxel from the dendrimeric complex was evaluated using membranes of cellulose acetate and quantified by HPLC. The release profile showed that after 156 hours at most 35% of the drug was released. The extended release is an advantage for the solid tumors treatment, because ideally the release system should keep the drug encapsulated during blood circulation and release it over time passively accumulated in the tumor site. Cytotoxicity was assessed in tumor cell line 4T1, using the MTT assay, the PAMAM-G4-NH2 paclitaxel complex showed cytotoxicity 5 times greater than the commercial formulation. In in vivo antitumor evaluation of the complex were evaluated curve of tumor growth, the weight record, the animal survival and cell proliferation with the antibody ki 67. Dendrimer complex had statistically significant effect in reducing tumor volume and through the immunohistochemical analysis the results were confirmed the reduction of cell proliferation. Therefore, the PAMAM-G4- NH2-paclitaxel complex can represent a promising strategy for the breast cancer treatment and should be further evaluated by means of clinical studies
238

Poliplexos de derivados de poli(succinimida), com/sem grupamento dodecil, e pEGFP-N3: síntese polimérica, transfecção e medida de expressão de GFP / Dodecylated and non-dodecylated poly(succinimide)-based polyplexes with pEGFP-N3 plasmid: polymer synthesis, plasmid transfection and GFP expression.

Kravicz, Marcelo Henrique 26 January 2018 (has links)
O uso de genes em terapias é um conceito originado em 1970 em consequência do crescimento exponencial de novas tecnologias para liberação de DNA, também pela capacidade de expressão de genes exógenos em células de mamíferos. Propomos, então, a síntese de polímeros catiônicos, em dois grupos, por meio da aminólise da poli(succinimida) (PSI): grupo 1An, polímeros catiônicos com arcabouço poli (ácido aspártico) com cadeias laterais contendo aminas protonáveis; grupo 2An, polímeros catiônicos anfifílicos, contenho o poli (ácido aspártico) como arcabouço, com aminas protonáveis e cadeias dodecilamina. Estudos de SEC mostraram que derivados dodecilados 2An tiveram tamanho menor que os polímeros do grupo 1An, não dodecilados. A capacidade tamponante para todos os polímeros sintetizados foi maior que o bPEI 25, e o grupo 2An apresentou as maiores capacidades tamponantes. Derivados 2An com as aminas A1 a A4 apresentaram menor CMC do que o grupo 1An. Citotoxicidade dos policátions foi dependente das suas concentrações e, entre todos os polímeros, aqueles com aminas A5 e A6 não foram citotóxicos. A presença da cadeia dodecilamina na PSI não diminuiu a viabilidade celular até 250 ?L-1, sugerindo que a porção hidrofóbica não é citotóxica na faixa de concentrações testada. A complexação do pEGFP-N3 com os derivados de PSI foi realizada, bem como a transfecção dos poliplexos em células HeLa. A expressão de GFP dos complexos obtidos com bPEI 25 foi quantificada e comparada com os poliplexos preparados com os derivados da PSI. Ensaios de transfecção mostraram que os derivados dodecilados da PSI apresentaram expressão negligenciável de GFP em células HeLa, sugerindo uma ligação forte entre plasmídeo e os derivados sintetizados e não-liberação do material genético nas células, ou dano celular causado pela cadeia hidrofóbica nas células. Os maiores valores de GFP quantificados foram encontrados nos poliplexos contendo polímeros não-dodecilados e com as aminas A3 e A4, nas razoes N:P 5 a 20 para A3 e N:P 5 para A4. Ambas as estruturas A3 e A4 fazem parte do core do bPEI 25. / Genes as drugs for human therapy is a concept originally conceived around 1970, a consequence of the exponential growth in knowledge of human gene function, the more effective technologies for DNA delivery, and the ability to transfer and express exogenous genes in mammalian cells. Here we propose synthesizing two small library groups of cationic polymers via aminolysis of poly(succinimide) (PSI) backbone: group 1An, polycationic polymers with a degradable amide of poly(aspartic) acid backbone, protonable oligoamine side chains into the main polymer structure, and group 2An, amphiphilic cationic polymers with a degradable amide of poly(aspartic) acid backbone, protonable oligoamine side chains into the main polymer structure and dodecyl side chain moieties. SEC showed that dodecylated derivatives 2An had lower size than 1An group, non-dodecylated polyelectrolytes. Buffering capacity of all synthesized polymers was higher than the standard bPEI 25, and the dodecylated 2An group had the highest buffering capacities values. 2An derivatives with amines A1 to A4 showed lower CMC than their non-dodecylated pairs. Cytotoxicity of all polycations was dependent on the concentrations, and among all polymers, those with amines A5 and A6 had lower cytotoxicity than bPEI 25. Moreover, the presence of the hydrophobic dodecyl side chain in the PSI backbone did not decrease the cell viability until 250 ?g mL-1 polymer concentration, thus suggesting the hydrophobic moiety is not cytotoxic in this range. Complexation of pEGFP-N3 plasmid with PSI derivatives grafted with amines A1 to A4 was performed, as well as the transfection of polyplexes into HeLa cells. GFP expression of bPEI25 polyplexes in different complex volumes was quantified and compared with PSI derivatives/pEGFP-N3 polyplexes. Transfection assays showed that dodecylated PSI derivatives had negligible or no GFP expression in HeLa cells, thus suggesting a strong interaction between polycations and pDNA or a cellular damage caused by the hydrophobic moiety, although cytotoxicity assay of polyplexes showed low cytotoxicity of polyplexes. The highest GFP expression values were found for polycations 1A3 and 1A4, both without the dodecylamine side chain, in the N:P ratios 5 to 20 for 1A3, and N:P ratio 5 for 1A4. Both amines A3 and A4 used for the PSI grafting are core structures of bPEI 25.
239

Processing of polymer-based systems for improved performance and controlled release

Ma, Jia January 2011 (has links)
This thesis focuses on improved processing methods for enhanced mechanical properties in polymer nanocomposites, and controlled drug release in polymer based delivery systems. Supercritical carbon dioxide assisted mixing was successfully used in preparation of polypropylene/sepiolite and polypropylene/multiwall carbon nanotube nanocomposites. Relatively homogeneous dispersed and well separated nanofillers were obtained throughout the PP matrix. A better preservation of nanofiller lengths was observed in the scCO 2 assisted mixing. Mechanical property studies showed a marked increase in Young's modulus and tensile strength with the addition of nanofillers. More interestingly, techniques usually designed to achieve high quality PP nanocomposites, such as the use of masterbatches, maleic anhydride grafted polypropylene compatibilizers or polymer coated MWNTs are not needed to achieve equivalent mechanical properties with scCO2 assisted mixing. ScCO2 was also used as a foaming technique to modify the traditional cured poly(ethyl methacrylate/tetrahydrofurfuryl methacrylate) system for a controlled release of chlorhexidine. Highly porous structures were produced and chlorhexidine released from scCO2 foamed samples was more than 3 times higher than traditionally cured samples. By altering the processing conditions, such as CO2 saturation time and depressurization time the CX release rate was altered. Finally, the electrospinning method was combined with the layering encapsulation technique in order to enable the incorporation of water-soluble drugs in poly(lactic-co-glycolic acid) fibres for biomedical applications. Water-soluble drug, Rhodamine 6G or protein bovine serum albumin, loaded calcium carbonate microparticles were successfully incorporated in PLGA fibres and a bead and string structured composite fibres.
240

Focused Ultrasound Mediated Blood-Brain Barrier Opening in Non-Human Primates: Safety, Efficacy and Drug Delivery

Downs, Matthew January 2015 (has links)
The blood-brain barrier (BBB) is physiologically essential for brain homeostasis. While it protects the brain from noxious agents, it prevents almost all currently available drugs from crossing to the parenchyma. This greatly hinders drug delivery for the treatment of neurological diseases and disorders such as Parkinson’s, Alzheimer’s and Huntington’s, as well as the development of drugs for the treatment of such diseases. Current drug delivery techniques to the brain are either invasive and target specific, or non-invasive with low special specificity. Neither group of techniques are optimal for long term treatment of patients with neurological diseases or disorders. Focused ultrasound coupled with intravenous administration of microbubbles (FUS) has been proven as an effective technique to selectively and noninvasively open the BBB in multiple in vivo models including non-human primates (NHP). Although this technique has promising potential for clinical outpatient procedures, as well as a powerful tool in the lab, the safety and potential neurological effects of this technique need to be further investigated. This thesis focuses on validating the safety and efficacy of using the FUS technique to open the BBB in NHP as well as the ability of the technique to facility drug delivery. First, a longitudinal study of repeatedly applying the FUS technique targeting the basal ganglia region in four NHP was conducted to determine any potential long-term adverse side effects over a duration of 4-20 months. The safety of the technique was evaluated using both MRI as well as behavioral testing. Results demonstrated that repeated application of the FUS technique to the basal ganglia in NHP did not generate permanent side effects, nor did it induce a permanent opening of the BBB in the targeted region. The second study investigated the potential of the FUS technique as a method to deliver drugs, such as a low dose of haloperidol, to the basal ganglia in NHP and mice to elicit pharmacodynamical effects on responses to behavioral tasks. After opening the BBB in the basal ganglia of mice and NHP, a low dose of haloperidol was successfully delivered generating significant changes in their baseline motor responses to behavioral tasks. Domperidone was also successfully delivered to the caudate of NHP after opening the BBB and induced transient hemilateral neglect. In the final section of this thesis, the safety and efficacy of the FUS technique was evaluated in fully alert NHP. The FUS technique was successful in generating BBB opening volumes larger on average to that of the BBB opening volumes in anesthetized experiments. Safety results through MRI verification as well as behavioral testing during application of the technique demonstrated that the FUS technique did not generate adverse neurological effects. Conversely, the FUS technique was found to induce slight positive effects on the response of the NHP to the behavioral task. Collectively, the work presented in this thesis demonstrates the safety and effectiveness of the FUS technique to open the BBB and deliver neuroactive drugs in the NHP.

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