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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.
21

Assessing Structure-Function Relationships in a Mouse Model of Emphysema using Ventilation and Perfusion (V/Q) SPECT/CT

McCurry, Cory January 2015 (has links)
Emphysema is a condition of the lung characterized by abnormal, permanent enlargement of the airspaces distal to the terminal bronchiole, accompanied by a destruction of their walls. The primary pathogenesis of emphysema is poorly understood. One of the major issues of COPD is that no diagnostic tests are sensitive enough to detect early disease. Standard pulmonary function tests (PFTs) do not explain the underlying pathophysiology of airflow limitation, nor do they provide information on how COPD may be affecting pulmonary blood flow. Functional imaging, specifically ventilation and perfusion (V/Q) Single Photon Emission Computed Tomography (SPECT), is a sensitive tool that can provide information on pulmonary function in different lung regions. When V/Q images are co-registered to CT, regional analysis can be coupled to structural information. The objective of this study was to examine how emphysematous change identified and localized by CT density based thresholds affects lung function as measured by V/Q SPECT in a mouse model of the disease. A dose response study was conducted where Female BALB/c mice were exposed intranasally to 0.0, 0.5, 2.5 and 5.0 units (U) of porcine pancreatic elastase (PPE). V/Q SPECT/CT scanning was performed 45 days post exposure, followed by measurement of lung compliance using the Flexivent® rodent ventilator 46 days post exposure. Whole lung slice analysis software was used to quantify airspace enlargement and alveolar capillary density from histological sections of the lung. CT pulmonary angiography (CTPA) was also performed on controls and mice exposed to 5 U PPE to examine vascular density. In this mouse model of emphysema, V/Q SPECT was useful in quantitatively examining how ventilation and perfusion is affected in mild and severe emphysema while providing evidence of low log(V/Q) ratio in otherwise normal lung densities. This could be caused by airflow obstruction as a result of widespread narrowing or loss of small conducting airways. Low log(V/Q) ratio is caused by mild emphysema indicating airflow obstruction or dysfunctional hypoxic vasoconstriction in underventilated regions of the lung. The majority of severely emphysematous regions of the lung have matched but equally reduced log(V/Q), although low log(V/Q) is also present. Pulmonary hypertension in response to chronic hypoxia may explain our finding of reduced perfusion activity and vascular density in emphysematous lung, but further research is required to investigate the presence of this pathology. V/Q SPECT was also shown to be superior in the detection of emphysema compared to CT and Flexivent measured lung compliance providing evidence towards shifting the current assessment and monitoring paradigms. Due to the widespread availability of this imaging technique, it could be used to screen asymptomatic smokers for early disease and identify and locate pathology so therapies targeting the appropriate disease pathway can be prescribed. This will inevitably improve patient care. / Thesis / Master of Science (MSc)
22

An investigtion of the polymicrobial nature of lower respiratory tract infections in cystic fibrosis patients

Nelson, Andrew January 2011 (has links)
Cystic fibrosis (CF) is a genetically inherited condition most prevalent amongst Caucasians. In previous studies, it has been demonstrated that bacterial, fungal and viral pathogens cause lung function decline and ultimately result in death due to respiratory failure. Patients with CF produce sputum daily, which makes it an ideal infection to study in terms of access to samples. However, it is unknown how transport of the samples from the patient to the laboratory will affect the results of molecular microbiological analysis. We found that the bacterial community profiles were significantly different in samples stored at room temperature from those which were refrigerated. Furthermore, a significant increase in bacterial load and numbers of Pseudomonas spp. and a significant decrease in number of H. influenzae were seen in the samples stored at room temperature. In this study we also aimed to characterise the factors which have an effect on the bacterial and fungal communities present in the CF lung in patients who possessed the F508del CFTR allele. We found that gender was a significant factor in the assembly of bacterial communities, due to a reduction in bacterial diversity and community evenness. Furthermore, we identified that P. aeruginosa colonisation affected bacterial community composition. We have also identified that bacterial community assembly in the CF lung appears to be stochastic. However, our data also shows that gender and P. aeruginosa colonisation affect assembly suggesting that, in some respects, a deterministic community assembly is also being observed. Our data also suggests that fungal communities are more diverse than is currently recognised. Additionally, we have found that patients who are homozygous for the F508del CFTR mutation harbour more rich fungal communities than patients who are heterozygous. A further objective was to follow these patients longitudinally to determine the stability of the CF lung microbiota, to determine the effects of antibiotic therapy, and to assess if any changes occurred in the CF lung during times of pulmonary exacerbation which could be identified as the causative agent. We did not find a significant relationship between exacerbations and the bacterial communities present in CF. However, in one patient we found that a particular bacterial taxa was present when the patient presented with an exacerbation but was absent when the patient was stable, suggesting that acquisition of a new bacterial taxa can potentially cause an exacerbation. We also found that an increase in bacterial load was not the cause of exacerbations in our cohort. Furthermore, the presence and abundance of fungal species was found not to be the cause of exacerbations.
23

Generic mass spectrometric workflows for mAb-related therapeutic protein quantification in pre-clinical species / Développement de nouvelles approches génériques de spectrométrie de masse pour la quantification de protéines thérapeutiques dans des études précliniques

Lanshoeft, Christian 08 December 2017 (has links)
Ce travail de thèse s’est focalisé sur le développement des approches génériques de spectrométrie de masse (MS) pour la quantification des anticorps monoclonaux (mAbs) et de leurs produits dérivés dans des études précliniques. Premièrement, le développement des protocoles de préparation d’échantillons basée sur la digestion directe à partir de sérum ou comportant une étape d’immuno-précipitation spécifique par anticorps a permis la quantification des mAbs couvrant une large gamme d'étalonnage de cinq ordres de grandeur. En outre, l'emploi de peptides provenant de la région constante du mAb a démontré la polyvalence de telles approches génériques de chromatographie liquide en tandem MS (LC-MS/MS). Deuxièmement, les instruments de MS à haute résolution (HRMS) ont étés évalués dans le cadre de cette thèse en tant qu'alternative aux spectromètres de masse de type triple quadripôle traditionnellement utilisés pour l’analyse bottom-up quantitative. L’avantage majeur de l’intégration des analyseurs de HRMS a été associé à la possibilité de l’analyse quantitative simultanée des mAbs et leurs produits associés directement au niveau de la protéine fournissant un niveau d'informations bien au-delà de celui obtenu avec des approches bottom-up. Par conséquent, l’apport essential de la HRMS pour les analyses qualitative et quantitative des protéines thérapeutiques de type mAbs et produits associés a été démontré dans cette thèse. / This PhD thesis focused on the development of generic mass spectrometry (MS)-based workflows for monoclonal antibody (mAb)-related therapeutic protein quantification in pre-clinical species. First, the development of bottom-up sample preparation protocols either based on direct serum digestion or immuno-capture allowed mAb-related therapeutic protein quantification over five orders of magnitude whereas the employment of peptides from the constant region of the mAb demonstrated the versatility of such generic liquid chromatography tandem MS (LC-MS/MS)-based approaches. Second, high-resolution MS (HRMS) instruments were evaluated as an alternative to triple quadrupole mass analyzers, traditionally utilized for bottom-up mAb quantification by LC-MS/MS. The major benefit of HRMS incorporation into the workflow was associated with the possibility to quantify simultaneously mAb-related therapeutic proteins directly at an intact level, providing an information level far beyond the one obtained with bottom-up LC-MS/MS methodologies. Hence, the pivotal role of HRMS for the qualitative and quantitative analyses of mAb-related therapeutic proteins was further outlined throughout this doctoral work.
24

Développement préclinique de sondes fluorées utilisées dans l'imagerie moléculaire des pathologies neurodégénératives / Pre-clinical development of fluorinated probes used in molecular imaging of neurodegenerative pathologies

Brun-Salabert, Anne-Sophie 08 October 2015 (has links)
Les mécanismes physiopathologiques liés aux maladies neurodégénératives restent encore largement méconnus. Deux processus semblent être particulièrement en cause dans les phénomènes de neurodégénérescence : la neurotoxicité par afflux massif de calcium due à une activation excessive des récepteurs NMDA (GluN) et la neurotoxicité par déstabilisation du cytosquelette du neurone par le biais de la phosphorylation anormale de la protéine tau. L'imagerie moléculaire par le biais de la tomographie par émission de positons (TEP) et de radiotraceurs, en étudiant les mécanismes moléculaires in vivo, permet de détecter et quantifier ces phénomènes. Ce travail a eu pour objet d'étudier un dérivé de la mémantine, un antagoniste des GluN se fixant sur un site intra-canal accessible uniquement lorsque ces récepteurs sont activés ce qui en fait donc un vecteur d'imagerie intéressant pour étudier leur activation. Nous avons mis au point la synthèse d'un nouveau radiotraceur dérivé de la mémantine : la [18F]-FNM (Fluoroéthylnormémantine). Il s'agit d'une synthèse par substitution nucléophile d'un groupement tosylate par du [18F], suivie d'une hydrolyse acide. Cette synthèse est reproductible avec un rendement de 10%, son activité spécifique est > 355 GBq/µmol. Chez le rat, le traceur passe la barrière hémato-encéphalique et sa distribution cérébrale est bien corrélée avec la localisation des GluN (r=0.622, p<0.0001). Sa cinétique de fixation (40 minutes) est compatible avec son utilisation en TEP. En ce qui concerne les tauopathies, la protéine tau stabilise l'organisation microtubulaire. Lors d'une phosphorylation anormale, l'interaction avec les microtubules diminue et les protéines tau vont s'accumuler en formant des Paires de Filaments en Hélice (PHF). Nous avons optimisé la radiosynthèse de l' [18F]-AV1451 ciblant les PHF. Notre rendement de synthèse est de 30% et l'activité spécifique du traceur > 10 GBq/µmol. Nous avons réalisé des autoradiographies sur des coupes de cerveaux atteints de tauopathie et nous avons constaté la capacité du traceur à différencier les coupes saines des coupes malades. La production de cet outil dans notre centre va nous permettre d'étudier la présence de PHF chez le marmouset, un primate particulièrement intéressant dans l'étude du vieillissement. Nous avons donc réalisé la synthèse de deux radiotraceurs innovants : la [18F]-FNM et le [18F]-AV1451, les synthèses sont reproductibles et les rendements compatibles avec des productions de doses en recherche pré-clinique et clinique. / The pathophysiological mechanisms associated with neurodegenerative diseases remain largely unknown. Two processes appear to be particularly involved in the phenomena of neurodegeneration: neurotoxicity induced by massive influx of calcium caused by excessive activation of NMDA receptors (GluN) and neurotoxicity by destabilization of neuron cytoskeleton through abnormal protein tau phosphorylation. Molecular imaging through positron emission tomography (PET) and radiotracers, by studying the molecular mechanisms in vivo, allows to detect and quantify these phenomena. This work was intended to study a memantine derivative, a GluN antagonist. We chose to develop a ligand that selectively binds to the ion channel in the open and active state which therefore makes it an interesting vector to study their overactivation. We have developed the synthesis of a new memantine analogue radiotracer: the [18F]-FNM (Fluoroéthylnormémantine). This is a synthesis by nucleophilic substitution of a tosylate with [18F], followed by acid hydrolysis. This synthesis is reproducible with a yield of 10%, its specific activity was> 355 GBq / µmol. In rats, the tracer cross the blood-brain barrier and brain distribution correlates well with the location of GluN (r = 0.622, p <0.0001). The binding kinetics (40 minutes) is compatible with its use in PET. Regarding tauopathies, the tau protein stabilizes microtubule organization. During abnormal phosphorylation, interaction with microtubules and tau proteins decreases and tau will accumulate to form Paired helical Filament (PHF). We optimized the radiosynthesis of [18F] AV1451 targeting 3 tau PHF. Our yield of synthesis is 30% and the specific activity of the tracer> 10 GBq / µmol. We made autoradiography on brains sections and have shown tracer ability to differentiate healthy and pathological slices. This tool will allow us to study the presence of PHF in marmosets, a particularly interesting primate in the study of aging. So we performed the synthesis of two innovative radiotracers: the [18F]-FNM and [18F]-AV1451, syntheses are reproducible and yields compatible with doses manufacturing in pre-clinical and clinical research.
25

Estudo fitoquímico e atividades biológicas preliminares de extratos de Polygonum Acre (Polygonaceae) H.B.K. e Synadenium Carinatum (Euphorbiaceae) Boiss

Sofiati, Filipe Toni [UNESP] 27 February 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:29:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-27Bitstream added on 2014-06-13T18:39:59Z : No. of bitstreams: 1 sofiati_ft_me_arafcf.pdf: 498028 bytes, checksum: f700c538895a18a84971f88a7fb19e6f (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Embora milhares de espécies vegetais sejam utilizadas na medicina tradicional do mundo, estima-se que apenas 1% são conhecidas por estudos científicos, com valor terapêutico demonstrado. As espécies Polygonum acre e Synadenium carinatum são de fácil cultivo, estando largamente distribuídas no Brasil, e possuindo um alto índice de utilização na medicina popular. Entre os usos populares da espécie Polygonum acre podem ser citados: anti-séptico, antiinflamatório, hipotensor, anti-hemorroidal, diurético, vermicida e anti-diarréico. A espécie Synadenium carinatum é popularmente utilizada para o tratamento de cânceres. No entanto, não existem estudos científicos que comprovem esses efeitos, nem informações sobre a segurança de utilização dessas drogas pelos seres humanos além de haver poucos estudos fitoquímicos destas espécies. Neste trabalho foram realizados os estudos fitoquímico, microbiológico, a busca de atividades biológicas dos extratos dessas plantas e a investigação de aspectos relativos à segurança de utilização. Os testes fitoquímicos indicaram a presença de flavonóides, taninos, saponinas, mono, sesqui e diterpenos, e derivados cinâmicos nas espécies P. acre e S. carinatum, enquanto que apenas a espécie P. acre respondeu positivamente quanto à presença de proantocianidinas condensadas e leucoantocianidinas. Na avaliação da atividade antimicrobiana através do método de difusão em ágar e da técnica de Concentração Inibitória Mínima, a espécie P. acre apresentou atividade antimicrobiana nas concentrações de 300 mg/mL, enquanto a atividade antimicrobiana para os extratos de S. carinatum não foi evidenciada. Nos testes de toxicidade aguda, pode-se observar que na dose de 2 g/kg, o extrato etanólico 70% de P. acre apresentou taxa de mortalidade de 50%, enquanto o extrato etanólico 70% de S. carinatum não apresentou toxicidade... / Although there are thousands of plant species used in traditional medicines in the world, it is estimated that only 1% are known by scientific studies with demonstrated therapeutic value. The species Polygonum acre and Synadenium carinatum are easy to culture, being widely distributed in Brazil, and having a high rate of use in folk medicine. Among the popular uses of the species Polygonum acre may be cited anti-septic, anti-inflammatory, hypotensive, anti-hemorrhoid, diuretic, vermifuge, and anti-diarrheal. The Synadenium carinatum species is popularly used in the treatment against cancer. However, there are no scientific studies that show these effects, no information about the safe use of these drugs by human beings and there are few phytochemical studies of this species. In this work, the phytochemical study and microbiological quality control, the search for biological activities of the extracts of plants and the investigation of aspects related to safe use were done. The phytochemical tests indicated the presence of flavonoids, tannins, saponins, mono, sesqui and diterpenes, and cinnamic derivatives in P. acre and S. carinatum species, while only the species P. acre responded positively about the presence of condensed proanthocyanidins and leucoanthocianidins. In the evaluation of antimicrobial activity by the ágar diffusion method and Minimum Inhibitory Concentration technique, the P. acre species had antimicrobial activity at concentrations of 300 mg / mL, while the antimicrobial activity for the extracts of S. carinatum was not demonstrated. In the tests of acute toxicity the ethanol extract 70% of P. acre at a dose of 2 g/kg showed 50% of mortality while the ethanol extract 70% of S. carinatum has no toxicity. At the dose of 1 g/kg the 70% ethanol extract of P. acre showed 50% of mortality while the latex of S. carinatum caused 100% of death the mice... (Complete abstract click electronic access below)
26

Investigation into the effects of specific muscarinic acetylcholine receptor antagonists on the myocardium in pre-clinical conditions of ischaemia reperfusion injury and oxidative stress model

Khan, J. January 2015 (has links)
Muscarinic acetylcholine receptors (mAChRs) are G-protein coupled receptors that mediate various actions of Acetylcholine (ACh) in the central nervous system and peripheral nervous system. In mammals, five distinct mAChR subtypes (M1-M5) have been recognised with the M2 subtype being predominantly present in the heart. The mAChR antagonists are routinely used for the treatment of various pathophysiological conditions including respiratory conditions. However, it has been postulated that mAChR antagonists may increase morbidity and mortality in chronic obstructive pulmonary disorder (COPD) and asthma patients with underlying cardiovascular disease, raising concerns regarding the cardiovascular safety of these agents. The current study was therefore undertaken to investigate the effects of individual mAChR antagonists in the setting of myocardial ischaemia reperfusion injury and oxidative stress models. We also investigated whether the inhibition of the mitochondrial permeability transition pore (MPTP) with cyclosporine-A (CsA) in the presence and absence of individual mAChR antagonists provided protection against ischaemia reperfusion injury. Furthermore, we also aimed to investigate the intracellular signalling pathway associated with mAChRs antagonists mediated myocardial injury under the stress conditions. Langendorff results showed that the non-selective M1-M3 mAChR antagonist, ipratropium bromide, the M2 mAChR antagonist, AF-DX 116 and the M3 mAChR antagonist, DAU 5884 significantly increased the infarct size to risk ratio of the heart in conditions of ischaemia and reperfusion. Detrimental effects of AF-DX 116 and DAU 5884 were abrogated by co-treatment of these drugs with mAChR agonist, acetylcholine (ACh) and/or CsA. Cell viability data of isolated cardiac myocytes revealed that AF-DX 116 and DAU 5884 caused a concentration dependent decrease in the viability of cardiac myocytes as well as causing a reduction in the time taken to depolarisation and hypercontracture under oxidative stress. AF-DX 116 and DAU 5884 significantly increased the levels of p-SAPK/JNK and decreased the levels of p-Akt and p-ERK. In addition, ACh and CsA showed to activate p-Akt and p-ERK. To conclude, the data suggest that AF-DX 116 and DAU 5884 caused cardiotoxicity at cellular, tissue and protein level in conditions of ischaemia reperfusion injury and oxidative stress. Furthermore, inhibition of the mitochondrial transition pore with CsA protected against the AF-DX 116 and DAU 5884 induced injury via activation of the pro-survival proteins, p-Akt and p-ERK.
27

Dementia care access and experience for South Asians in the UK : the influence of Hindu, Sikh and Muslim religions

Regan, Jemma January 2013 (has links)
Background: In the UK, South Asian and Black Caribbean communities are more at risk of developing vascular dementia and experience a higher rate of young onset dementia (under age 65 years), compared with the majority ethnic population (Seabrooke & Milne, 2004). Despite this, Black and Minority Ethnic (BME) persons with dementia are underrepresented in health services, receive diagnoses later in disease progression and are less likely to access anti-dementia medication or partake in research trials (Cooper, Tandy, Balamurali et al., 2009). An emerging theme in culture and dementia research is the impact of religion on dementia in terms of perceiving the illness, accepting the illness, coping with the illness and accessing services (Milne & Chryssanthopoulou, 2005). Religious beliefs and practices offer one explanation for BME underrepresentation in mainstream health and social care services (MHSCS). MHSCS appear ill-equipped to respond to the religious needs of ethnic minority individuals (Bowes & Wilkinson, 2003). Aim: To conduct an investigation of the influence of religion on access to - and experiences of - dementia care services, for South Asians from the Sikh, Hindu and Muslim communities in the West Midlands. Method: An exploratory, qualitative study employing Critical Realist Grounded Theory methodology (Strauss & Corbin, 1990) utilising a multimethods approach of semi-structured interviews and observations informing a three-phase data collection and data analysis model with five service user and service provider cohorts. Results: A two-stage model: “Existing Service Provision” and “Service Improvements” demonstrates religious beliefs influence low knowledge of dementia, stigma of mental illness, isolation and family duty of care. This led to ill-informed care choices and carer burden. Persons with dementia were also under-identified within their religious communities. Regular outreach in to South Asian religious communities is vital to educate and identify underrepresented persons, allow informed dementia care choices and relieve carer burden. Scripture-influenced dementia training is required to dispel stigma and improve care options. Investment in face to- face communication with translators and a shift away from paper resources is required. Conclusion: The full potential of religious communities in dementia care provision is yet to be realised. Utilising this resource as a symbiotic channel – firstly, to identify persons with dementia and educate the congregation about dementia - and secondly, to utilise the existing congregation to meet the psycho-social needs of the person with dementia, offers a holistic care package, leading to informed care choices.
28

COMBATING THE HIV/TB CO-INFECTION SYNDEMIC: TESTING A NOVEL RESPIRATORY MUCOSAL ADENOVIRAL TUBERCULOSIS VACCINE IN NAÏVE AND HIV-INFECTED HUMANIZED MICE / TESTING A TB VACCINE IN HUMANIZED MICE IN THE CONTEXT OF HIV

Chacon, Alexis January 2023 (has links)
HIV and Tuberculosis (TB) co-infection place an immense burden on health care systems as they act in synergy to worsen disease prognoses. TB is the most common cause of death in people living with HIV (PLWH) and in turn, HIV is the most significant risk factor for progressing from latent to active TB disease. While HIV and TB are endemic in sub-Saharan Africa, they also disproportionately affect marginalized populations in Canada. Unfortunately, the only licensed TB vaccine, BCG, does not protect from adult pulmonary TB and is not recommended for PLWH. Thus, the development of novel TB vaccines, which are safe and effective in PLWH, remains an urgent global necessity. We have found that humanized mice (hu-mice) are ideal models to research this as they can be successfully infected with HIV, TB and HIV/TB and recapitulate human disease pathology. A next-generation respiratory mucosal (RM) trivalent chimpanzee adenoviral-vectored vaccine (Tri:ChAd68) was developed and tested in our naïve and HIV-infected hu-mice. When immunizing naïve hu-mice, a trend of increased M.tb-specific CD4+ T cells producing IFNγ and TNFα in the lungs and spleen was observed. After subsequent M.tb infection, the vaccinated naïve hu-mice also exhibited significantly reduced lung mycobacterial burden, tissue dissemination and lung pathology. We then investigated the vaccine immunogenicity and ability to protect from TB in the context of HIV. Our immunized HIV-infected hu-mice were also able to produce M.tb-specific T cells and when challenged with M.tb, we observed a decreased trend in mycobacterial load in the lungs, indicating that the vaccine may be able to offer protection against TB when a prior HIV infection is present. These findings demonstrate the protective potential of the RM Tri:ChAd68 vaccine against TB disease for PLWH. In the future, we will test this vaccine in antiretroviral treated HIV-infected hu-mice to increase clinical significance. / Thesis / Master of Science in Medical Sciences (MSMS) / HIV and TB are major diseases that can occur together, severely worsening patients’ health and challenging global healthcare systems. The current TB vaccine, BCG, isn’t ideal for people living with HIV (PLWH), causing this vulnerable population to be at greater risk of getting TB infection. Therefore, developing a new TB vaccine that is safe and effective in PLWH is an urgent global issue. We used humanized mice that develop human immune cells to test a novel TB vaccine delivered to the lungs (Tri:ChAd68) to see if it could protect against TB and overcome immune challenges from HIV. We saw increased immune responses and lower TB infection in our vaccinated humanized mice and the vaccine appeared to also be beneficial in the mice that had prior HIV infection. This suggests the Tri:ChAd68 vaccine may be able to offer protection against TB in PLWH; however, more studies are needed to conclude this.
29

DEVELOPMENT OF PORCINE TISSUE ENGINEERED CARTILAGE FOR PRE-CLINICAL STUDIES

Falcon, Jessica M, 0000-0001-6829-1826 January 2020 (has links)
Damage to the hyaline articular cartilage that cushions joints is exceedingly common worldwide, whether caused by traumatic injuries or degenerative pathologies that can lead to the onset of osteoarthritis. Clinically, cartilage lesions are treated with surgical procedures that attempt to restore the architecture of the hyaline tissue. Unfortunately, the current treatment options often result in the undesired formation of fibrocartilage, a type of cartilage with mechanical properties that are inferior to those of hyaline cartilage. The ability to withstand constant mechanical load is the primary function of articular cartilage, and therefore, critical to restore. The field of cartilage tissue engineering aims to address the limitations of current treatment options by generating restorative tissue with cartilaginous protein composition and concomitant mechanical competency of native hyaline cartilage. Efforts to recapitulate functional cartilage often include approaches that start with cells seeded on a scaffold. Scaffolds are employed to provide the mechanical structure while cells execute the formation of the extracellular matrix. Furthermore, adult mesenchymal stem cells (MSCs) are used in combination with chondrocytes, the single cell type of cartilage, to enhance chondrogenic composition. Given the possible adult MSC sources, such as bone marrow, adipose tissue or the synovial membrane, it is important to select the source that will yield maximum cartilage differentiation. However, the multi-lineage differentiation capacity of MSCs is also their intrinsic limitation. Stem cells undergoing differentiation to cartilage formation can transition into bone, a process known as hypertrophy, which yields changes in chondrocyte function and subsequent undesired deposition of mineralized matrix instead of a normal chondral matrix. The overarching hypothesis of this thesis is that using cartilage-specific MSCs from the synovial membrane, a tissue adjacent to the articular surface, will generate cartilage with superior properties when compared to tissue derived from other cell sources. This hypothesis was tested in the following four aims: First, to assess the in vivo response of tissue engineered cartilage generated from gold standard bone marrow-derived MSCs in a preclinical minipig model; second, to compare the chondrogenic capacity of synovial MSCs and bone marrow MSCs in scaffold-free and scaffold-based engineered cartilage; third, to challenge scaffold-based engineered cartilage with a hypertrophic environment and evaluate the response; and fourth, to explore the use of a hypoxia-simulating agent for the enhancement of chondrogenic differentiation. Together these studies contribute to the identification of an optimal cell source for cartilage tissue engineering to be used in translational preclinical models. / Bioengineering
30

Pre-clinical development of viral vectored transmission-blocking malaria vaccines

Kapulu, Melissa Chola January 2014 (has links)
Malaria transmission-blocking vaccine candidate antigens have been developed to induce antibodies using different delivery systems, mainly protein-in-adjuvant formulations, independently in various laboratories giving varied transmission-blocking activity (TBA). However, only one candidate antigen has been tested in clinical trials. In order to advance the most efficacious target(s) for possible clinical development, a rank order of the leading antigens based on TBA in a head-to-head comparison using a single delivery platform was made. Candidate antigens, AnAPN1, PfsHAP2, Pfs230-C, Pfs25, and Pfs48/45 (with or without N-glycosylation site substitution), were generated as recombinant viral-vectored vaccines using simian adenovirus and modified vaccinia Ankara and administered to mice in a heterologous prime-boost regimen. Vaccine-induced antibody responses were induced to all except PfsHAP2 were maintained up to ten and a half months post-boost. TBA was assessed at the peak response against Plasmodium falciparum NF54 laboratory strain and African field isolates by ex vivo membrane feeding assays in Anopheles stephensi and A. gambiae respectively. Antibodies to three antigens [Pfs230-C, Pfs25 and Pfs48/45+<sub>NGln</sub>] had TBA against P. falciparum NF54, and those against Pfs230-C and Pfs25 consistently showed efficacy regardless of the parasite exposure in both mosquito species. Further analysis of antibody responses to these two candidate antigens showed concentration-dependent efficacy against P. falciparum field isolates. In a rabbit study, responses to Pfs230-C, Pfs25 and Pfs48/45+<sub>NGln</sub> also showed IgG concentration-dependent efficacy. To assess TBA against AnAPN1, antibody responses to three fragments were tested. TBA was observed only against N-terminal 135 amino acid fragment. Pfs230-C and Pfs25 were generated as fusion vaccines using either a self-cleaving or glycine-proline linker sequence. Comparable antibody responses were induced between the two fusion strategies that had synergistic effects at inhibiting P. falciparum NF54 development in A. stephensi.

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