Thesis (M. Res. (Med.))--University of Hong Kong, 200.

Freie Universiẗat, Diss., 2005--Berlin. / Dateiformat: zip, Dateien im PDF-Format. Erscheinungsjahr an der Haupttitelstelle: 2005.

Η ουδετεροπενία που σχετίζεται με τη χημειοθεραπεία, είναι μια συχνή ανεπιθύμητη ενέργεια της θεραπείας κατά του καρκίνου, η οποία κάνει τους ασθενείς πιο ευπαθείς σε λοιμώξεις απειλητικές για τη ζωή. Ο κίνδυνος για εμπύρετη ουδετεροπενία ποικίλει ανάλογα με το σχήμα της χημειοθεραπείας και διάφορα χαρακτηριστικά του ασθενούς, όπως η μεγάλη ηλικία ή σοβαρές συνοδές παθήσεις. Διάφορες κλινικές μελέτες έδειξαν ότι η χορήγηση αυξητικών παραγόντων των κοκκιοκυττάρων (G-CSFs) μειώνει σημαντικά τον κίνδυνο για εμπύρετη ουδετεροπενία. Η μείωση κινδύνου που αναφέρεται σε κλινικές μελέτες, κυμαίνεται από 8% μέχρι 37%, και η διακύμανση του ποσοστού αυτού αντικατοπτρίζει διαφορές στον κίνδυνο εμπύρετης ουδετεροπενίας που σχετίζεται με το σχήμα της χημειοθεραπείας. Το πρόβλημα που περιορίζει τη χορήγησή τους είναι το μεγάλο κόστος που έχουν. Επομένως, η τελική απόφαση για τη χορήγηση αυτών των φαρμάκων βασίζεται στις μελέτες αποτελεσματικότητας του φαρμάκου. Σκοπός της μελέτης ήταν η διερεύνηση του πραγματικού ποσοστού εμφάνισης εμπύρετης ουδετεροπενίας σε ασθενείς με διάφορους συμπαγείς όγκους συμπεριλαμβανομένων και των λεμφωμάτων στους οποίους χορηγήθηκε αυξητικός παράγοντας αποικιών κοκκιοκυττάρων. Επιπρόσθετα μελετήθηκε ο συσχετισμός του ποσοστού εμφάνισης εμπύρετης ουδετεροπενίας με διάφορους παράγοντες που μπορεί να επηρεάζουν την εμφάνιση της. Τέλος, πραγματοποιήθηκε ανάλυση κόστους-αποτελεσματικότητας της δευτερογενούς χορήγησης αυξητικού παράγοντα στο Κέντρο. Σε μια αναδρομική μελέτη μελετήθηκαν 482 ασθενείς οι οποίοι έλαβαν αυξητικό παράγοντα (λενογραστίμη) είτε ως πρωτογενή είτε ως δευτερογενή προφύλαξη. Η συλλογή των δεδομένων έγινε καταγράφοντας στοιχεία από τους φακέλους με το ιατρικό ιστορικό των ασθενών, από το λογισμικό πρόγραμμα Power Pro του φαρμακείου (ιστορικό φαρμάκων κάθε ασθενούς) και από το λογισμικό πρόγραμμα MOSAIQ του Κέντρου (αιματολογικές εξετάσεις των ασθενών). Μετά από πρωτογενή προφύλαξη με λενογραστίμη εμφανίστηκαν 38 εμπύρετα επεισόδια σε 30/367 (8,2%) ασθενείς, ενώ μετά από δευτερογενή προφύλαξη εμφανίστηκαν μόνο 5 εμπύρετα επεισόδια σε 5/115 (4,3%) ασθενείς. Από τη στατιστική ανάλυση δεδομένων προκύπτει ότι σημαντικοί προδιαθεσικοί παράγοντες για την εμφάνιση εμπύρετης ουδετεροπενίας ήταν το φύλο (p=0,015), η προηγούμενη ή ταυτόχρονη ακτινοθεραπεία (p=0,040) και ο αριθμός συνοδών παθήσεων (p=0,014). Με την αύξηση της διάρκειας χορήγησης λενογραστίμης μειώθηκε σημαντικά ο αριθμός επεισοδίων εμπύρετης ουδετεροπενίας ανά ασθενή (p=0,0067), η διάρκεια νοσηλείας στο νοσοκομείο (p=0,02), ενώ αντίθετα αυξήθηκαν οι ανεπιθύμητες ενέργειες οι οποίες παρατηρήθηκαν σε 153/482 (31,7%) ασθενείς (p=0,029). Η πιο συχνή ανεπιθύμητη ενέργεια που εμφανίστηκε ήταν ο πόνος στα οστά σε 148/482 (30,7%) ασθενείς, παρόλα αυτά σε 124/148 (83,8%) ασθενείς θεραπεύτηκε με χορήγηση παρακεταμόλης. Σύμφωνα με τα αποτελέσματα της ανάλυσης κόστους-αποτελεσματικότητας η χορήγηση χημειοθεραπείας με δευτερογενή προφύλαξη με λενογραστίμη σε ασθενείς «χαμηλού κινδύνου» παρουσιάζει υψηλότερη κλινική αποτελεσματικότητα από τη μη προφύλαξη, η οποία επέφερε τη μείωση του συνολικού κόστους ανά ασθενή που θεραπεύεται. Συμπερασματικά, φαίνεται ότι η λενογραστίμη αποτελεί υποψήφιο είδος G-CSF με ελκυστικά χαρακτηριστικά για χορήγηση σε ουδετεροπενικούς ασθενείς με πυρετό. Τα ποσοστά εμπύρετης ουδετεροπενίας που εμφανίστηκαν, αν και ήταν υψηλά, παραμένουν μικρότερα από αυτά που παρατηρήθηκαν την ίδια χρονική περίοδο σε πολλά κέντρα του εξωτερικού. Η δευτερογενής προφύλαξη με λενογραστίμη σε ασθενείς «χαμηλού κινδύνου» εκτιμάται ως η κυρίαρχη επιλογή τόσο από πλευράς κλινικής αποτελεσματικότητας όσο και από πλευράς κόστους-αποτελεσματικότητας. / Chemotherapy-induced febrile neutropenia (FN) is a serious side effect of cancer treatment, commonly occurring during the initial cycles of cytotoxic therapy and increasing in frequency with both the depth and duration of neutropenia. The risk of developing FN appears to depend on a variety of factors, including tumor type, chemotherapy regimen and patient-related risk factors. Myeloid growth factors have been shown to reduce the incidence, duration, and severity of neutropenic events across a broad range of malignancies and regimens, often enabling the delivery of full chemotherapy dose intensity. A major limitation of the use of G-CSFs is the ability to predict which patients are at risk of developing neutropenic complications as administration is costly. The purpose of this study was to: (1) evaluate the real-world incidence of FN in patients with solid tumors, including lymphoma, after receiving lenograstim, (2) analyse factors that predict the occurrence of chemotherapy-induced myelosuppression, and (3) evaluate the cost-effectiveness of secondary prophylaxis with lenograstim. The study conducted in Bank of Cyprus Oncology Center at Nicosia. A total of 482 patients who received G-CSF between February 2008 and January 2010 were identified and selected from the pharmacy records. Data were retrospectively obtained from the medical records and records with the blood cell accounts. Results were recorded and analyzed using a database system (SPSS). The incidence of FN after primary prophylaxis with lenograstim was 8,2% and after secondary prophylaxis was 4,3%. Analysis of the results showed that gender (p=0,015), prior or concurrent radiation (p=0,040) and comorbidities (p=0,014) were associated with the risk of severe and febrile neutropenia. The use of CSFs in patients with established FN reduces the amount of time spent in hospital (p=0,02), while side effects were increased (p=0,029). Bone pain was reported in 30,7% patients receiving lenograstim and was treated with paracetamol in 83,8% patients. Secondary prophylaxis with lenograstim improved health outcomes with a very limited cost. In this retrospective study lenograstim was shown to be effective in the prophylaxis of chemotherapy-induced neutropenia. Gender, prior or concurrent radiation and comorbidities were prognostic factors for neutropenia. Also, secondary prophylaxis in low risk patients was cost-effective at the current official price in Cyprus.

The discovery of the existence of the cell membrane has led to a search for its organization on a molecular scale. The advent of artificial lipid bilayers and the development of electron microscopy in the 1930's provided direct visual evidence for the existence of the cell membrane and drove forward models of membrane structure based its known composition of proteins, lipids and carbohydrates. The fluid mosaic model of membrane structure, based on thermo- dynamics and newly developed protein structural studies of the time, placed integral globular membrane proteins within a fluid phospholipid bilayer. This model allowed for the association of proteins into groups and the possible mobility of proteins within the lipid bilayer. At the the same time fluorescence microscopy demonstrated movement of proteins in the plane of the lipid bilayer. Since then experimental techniques have been developed that show protein complexes of varying sizes do exist and so this gives us the opportunity to ask how receptor proteins fit into the molecular organization of the cell membrane. This thesis presents an investigation into how the epidermal growth factor receptor (EGFR) organizes in the cell membrane of colorectal carcinoma cells. First a new cell line for studying the receptor by stably expressing the epidermal growth factor receptor conjugated to enhanced green fluorescent protein (EGFR-eGFP) in SW620 cells was developed. This is an interest- ing cell line because it originates from a colonic adenocarcinoma that during the process of metastasis has lost the ability to express the EGFR. It therefore provided an environment for the expression of the fluorescent form of the receptor more in keeping with its natural environment. The technique of total internal reflection fluorescence (TIRF) microscopy was used to visualize the fluorescently tagged receptor in the cell membrane. This technique uses the principles of total internal reflection to excite fluorescence in molecules located only 100 nm into the cell. Because sources of fluorescence from outside the illuminated area are minimized individual fluorescent molecules can be imaged. The spots in the images, produced by the fluorophores, were detected using a single molecule detection and tracking algorithm. The intensities of these detected spots were analysed and compared with that from a single molecule of enhanced green fluorescent protein (eGFP). This gave an estimate of the number of receptors contained within each receptor complex. Before ligand binding most of the receptors were found to be located in complexes containing up to eight molecules and most frequently they were found in complexes of two molecules. Larger complexes of receptors were found to have formed after activation of the receptor by its ligand.

Human adult mesenchymal stem cells (MSCs) derived from bone marrow have the capacity to self-renew and to differentiate into a variety of cells and tissues. They can leave their niche to migrate to remote tissues where they play a critical role in angiogenesis, wound repair and tissue regeneration. A major goal in adult stem cell research is to define how MSC fate is controlled by the pericellular extracellular matrix (ECM) and soluble factors that largely constitute their tissue-specific niches. Defining crucial regulatory signals that control the fate and function of MSCs in vitro will contribute to the development of therapeutic strategies to improve tissue regeneration. The objective of this study was to investigate the molecular relationships between cell-ECM integrin receptors and platelet-derived growth factor receptor (PDGFR) tyrosine kinases, which are crucial in modulating MSC expansion, recruitment, and differentiation towards a number of different cell lineages. This study reports that ECM-directed cross-talk between PDGFR-β and alpha5β1 integrin controls the migration of MSCs. Cell adhesion to fibronectin induced integrin alpha5β1-dependent phosphorylation of PDGFR-β in the absence of growth factor stimulation. Phosphorylated PDGFR-β co-immunoprecipitated with integrin alpha5 and co-localised with alpha5β1 in a transient tidemark of focal adhesions. Adhesion to fibronectin also strongly potentiated platelet-derived growth factor (PDGF)-BB-stimulated PDGFR-β phosphorylation, in an alpha5β1-dependent manner. PDGFR-β-activated phosphatidylinositol 3 ́-kinase (PI3-kinase) and Akt activity, actin reorganisation and cell migration were all regulated by fibronectin engagement of alpha5β1 integrin. This synergistic relationship between integrin alpha5β1 and PDGFR-β is a fundamental determinant of mesenchymal cell migration. Thus, fibronectin-rich matrices can prime PDGFR-β to recruit mesenchymal cells at sites of tissue remodelling.

Tendon plays an important role in regulating body locomotion and providing additional stability to the body. However, tendon is susceptible to injuries and the healing process could be devastating along with the several issues, namely adhesion formations, slow healing and failure at fixation sites, which have deferred the success of proper tendon healing via tendon tissue engineering. This dissertation thus aims to create a sustained dual-drug therapy to address these issues. For adhesion formation, naproxen sodium (NPS) has been shown to be able to avoid this symptom through inhibiting inflammation process.

Transmissible spongiform encephalopathies (TSEs) are rare, uniformly fatal neurodegenerative disorders that can affect many mammalian species, including humans. A hallmark of these diseases is the conversion of cellular prion protein (PrPC) into an abnormally folded form. This misfolded PrPC is infectious, since it can provide a template for pathogenic conversion of PrPC in a new host. In addition to any toxicity of the misfolded protein, loss of normal PrPC function could be involved in the neurodegenerative processes. However, the physiological role of PrPC is still poorly understood and this project has aimed to address that lack of knowledge. Out of the many putative functions ascribed to PrPC, the most commonly proposed is that it protects cells from stress. In contrast, I have found that stable transfection of the prion protein gene into SH-SY5Y neuroblastoma cells increases cell death in response to serum removal from the culture medium. Following treatment with several chemical toxins, two out of four stably transfected clones did, generally, display greater viability than untransfected cells that do not express detectable levels of PrPC. However, knockdown of PrPC expression by RNA interference had no effect on this stress resistance, indicating that it may not have been mediated directly by PrPC. Given the lack of robust stress protection afforded by PrPC transfection, proteomic analyses of the cells were carried out to identify alternative processes that were perturbed as a result of PrPC expression. The results obtained suggested roles for PrPC in cytoskeletal organisation and cell cycle regulation. Various proteins involved in cytoskeletal organisation were confirmed by western blotting to be differentially expressed in some or all of the stably transfected clones. Additionally, the expression changes to proteins involved in cell cycle regulation resulted in slower proliferation of the clones compared with untransfected cells, a difference that was reduced following RNA interference-mediated knockdown of PrPC. Taken together, these data suggested that specific growth factor-activated pathways were differentially regulated in the stably transfected clones. One candidate pathway was nerve growth factor (NGF) signalling, which promotes neuronal survival and differentiation as well as regulating various processes outside of the nervous system. PrPC-transfection resulted in altered expression of receptors for NGF, suggesting that the stably transfected clones were, indeed, responding differently to NGF stimulation. However, the molecular mechanism responsible for these expression changes remains to be determined, since co-immunoprecipitation experiments did not identify any physical interactions between PrPC and the NGF receptors. Nonetheless, a role for PrPC in modulating NGF signalling has the potential to explain many of the diverse phenotypic observations in PrPC-null mice and might indicate that loss of PrPC function is an important part of TSE pathogenesis.

Made available in DSpace on 2014-06-11T19:28:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-03-01Bitstream added on 2014-06-13T18:07:24Z : No. of bitstreams: 1 silverio_kg_me_arafo.pdf: 1644294 bytes, checksum: 5d943591d5c51a3846c75163db9a2ebb (MD5) / O objetivo do presente estudo foi avaliar in vitro o efeito do condicionamento radicular com fator de crescimento de fibroblastos básico (b-FGF) sobre a morfologia e densidade de fibroblastos. Para tal, blocos de dentina com 4 mm2 de área de superfície foram obtidos de raízes de dentes humanos extraídos devido severo envolvimento periodontal, sendo instrumentados manualmente e autoclavados. Noventa amostras foram selecionadas aleatoriamente e distribuídas em 3 grupos segundo o tratamento de superfície prévio ao condicionamento com o b-FGF: sem tratamento - controle; 50 mg/mL de cloridrato de tetraciclina e EDTA a 24%. As 30 amostras de cada um destes 3 grupos foram distribuídas em 3 subgrupos quanto à dose de b-FGF: 0 æg/mL - controle; 50 æg/mL e 125 æg/mL. Após os tratamentos, as amostras foram incubadas a 37º C e 98% de umidade com 2mL de meio Eagle, sendo 1mL com fibroblastos de linhagem contínua (células McCoy) na concentração de 1 x 105 células/mL e 1mL meio sem células, por 24 h. Após as 24 h, as amostras foram submetidas a preparo de rotina para MEV e então, fotomicrografadas nos aumentos de 500X (densidade celular) e 1000X (morfologia celular). Em seguida, as fotomicrografias foram avaliadas por 3 examinadores treinados, calibrados, independentes e cegos, os quais verificaram morfologia e densidade celular segundo os escores propostos por Gamal et al. (1998) e Jenkins et al. (1988), respectivamente. A aplicação da Análise de Regressão pela Técnica da Árvore demonstrou haver diferenças estatisticamente significantes para a densidade celular (p<0,0001) entre os grupos EDTA, tetraciclina e controle, sendo que também houve diferenças entre as doses de 0/50 æg e 125 æg de b-FGF nas amostras condicionadas com EDTA (p<0,0001) e entre as doses de 0 e 50/125 æg de b-FGF nas amostras condicionadas com tetraciclina... . / The aim of this study was to evaluate in vitro the effect of the root surface conditioning with basic fibroblast growth factor (b-FGF) about morphology and density of fibroblasts. Dentin slices of with 4 mm2 of surface area were obtained from roots of teeth extracted due to severe periodontal involvment. These were scaled and sterilized. Ninety samples were randomly distributed into 3 groups according to treatment before application of b-FGF: non-treated - control; 50mg/mL of tetracycline HCl and EDTA 24%. The thirty samples of each group were distributed into 3 subgroups according to the concentration of b-FGF: 0 æg/mL - control; 50 æg/mL and 125 æg/mL. After treatments, the samples were incubated at 37ºC and 98% humidity with 1mL of Eagle Medium with 1 x 105 cells/mL of fibroblast from continuos lineage (McCoy Cells) plus 1mL this solution without cells during 24 hours. The samples were submitted to routine preparation for SEM and photographed at 500x (density celular) and 1000x (morphology celular). Three independent and blind examiners evaluated the fibroblast`s morphology and density, according to Gamam et al. (1998) and Jenkins et al. (1998), respectively. Classification and Regression Trees test results indicated significant differences on the density (p<0,0001) among EDTA, tetracycline and control groups with also differences between concentrations of 0/50æg and 125æg of b-FGF at the samples conditioning with EDTA (p<0,0001) and between concentrations of 0 and 50/125 æg of b-FGF at the samples conditioning with tetracycline(p<0,0001). The results of this test to morphology indicated significant differences between treatment or non-treatment with b-FGF, and that concentration of 125 æg demonstrated to be more favorable than the concentration of 50 æg. In conclusion, the treatment of root surfaces with b-FGF influenced the density... (Complete abstract, click electronic address below).

Over the past few years, researchers have focused their attention on the development of targeted cancer therapies to minimize the side effects associated with non-targeted treatments such as chemotherapy. Specifically, these approaches have focused on blocking growth factor receptors (GFR) that are overexpressed in cancer cells. In this thesis, we also focus on targeting overexpressed GFR; however, instead of blocking the GFR, our novel approach aims at using them to selectively enhance the endocytotic process of macropinocytosis to deliver peptides that either disrupts the mitochondria or inhibits glycolysis. Herein, we show the selective enhancement of macropinocytosis by the fusion protein comprised of the keratinocyte growth factor (KGF) fused to elastin like polypeptide (ELP), KGF-ELP. Furthermore, we report the synthesis of the fusion protein consisting of mitochondriotoxic peptide (KLAKLAK)2 with ELP, (KLAKLAK)2-ELP. We show that (KLAKLAK)2-ELP forms nanoparticles (NPs) that are internalized via macropinocytosis and their internalization is facilitated by the interaction between the ELP domain and heparan sulfate proteoglycan (HSPG) on the cell surface. This internalization results in mitochondrial swelling, depolarization and subsequent cell death. Moreover, we show that heterogeneous NPs comprising of the two fusions KGF-ELP and (KLAKLAK)2-ELP selectively kill lung cancer cells expressing the keratinocyte growth factor receptor (KGFR). We also report the synthesis of the fusion consisting of peptides derived from a phosphorylated domain of the glycolytic enzyme phophoglycerate mutase (PGM) and ELP, PGM-ELP. We demonstrate that this fusion inhibits the step in glycolysis that converts 3-phosphoglycerate (3PG) to 2-phosphoglycerate (2PG); the results show that cell death occurred preferentially in lung cancer cells compared to normal cells. Additionally, the heterogeneous NPs comprising of KGF-ELP and PGM-ELP selectively enhanced killing in lung cells with high levels KGFR. Finally, the synthesis of a fusion proteins consisting of four PGM domains fused to ELP, (PGM)4-ELP, exhibits higher cytotoxic effect and efficiency when compared to the single PGM domain fusion, PGM-ELP. Overall, we conclude that targeting overexpressed growth factor receptors to stimulate macropinocytosis can be a tremendously selective therapy for the treatment of lung cancer. This can result in attenuating side effects and improvement of the patient’s prognosis

The purpose of this study is to demonstrate the effectiveness of spheres-in-tube structured scaffolds to sequentially deliver two biomolecules during two phases of tissue regeneration following spinal cord injury (SCI). Scaffolds were synthesized of a poly (lactic-co-glycolic acid) (PLGA) base combined with Poly (L-lactic acid) / Poly (ε-caprolactone) (PLLA/PCL) microspheres. The scaffolds are constructed by leveraging the different solubilities of PLGA, PLLA and PCL in super critical carbon dioxide and ethyl acetate during fabrication processes. Microspheres can reduce the pore size and porosity of PLGA scaffolds; this enhances their mechanical strength and enables them to provide long-term treatment without collapse. The release of the epidermal growth factor (EGF) and basic fibroblast growth factor (FGF-b) are being used to study the release profiles of the designed scaffolds. The analysis shows that FGF-b is released from high porosity PLGA base as the first delivery vehicle and completes the release in the first week. PLLA or PCL microspheres, having the property of sustainably delivering encapsulated EGF in 36 days, are used as the second drug delivery vehicle. FGF-b released within the first week can mimic biomolecules used to protect the surviving neurons and promote the development of sprout axons. The sustained release of EGF from microspheres is used for long-term therapy to differentiate multipotent cells into determined types at the injury site. The results demonstrate that these enhanced parameters along with the ability of sequential co-delivery of growth factors, make these designed scaffolds a promising candidate in SCI studies.