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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.
661

Synthesis and biological evaluation of 6-substituted coumaranone derivatives and related compounds as monoamine oxidase inhibitors / Adriaan Sarel van Dyk

Van Dyk, Adriaan Sarel January 2014 (has links)
Parkinson’s disease (PD) is an age related neurodegenerative disorder that presents with both motor and non-motor symptoms. The most common pathological characteristic of PD is the loss of the pigmented dopaminergic neurons of the substantia nigra pars compacta (SNpc), with the appearance of intracellular inclusions known as Lewy bodies in the affected neurons. The loss of the SNpc neurons results in a deficiency of dopamine in the nigrostriatal pathway of the brain, and it is this deficiency that is responsible for the motor symptoms of PD. Monoamine oxidase B (MAO-B) is predominantly found in the striatum and is responsible for the oxidative metabolism of dopamine. The first-line treatment of PD is dopamine replacement therapy with levodopa, the metabolic precursor of dopamine. Rapid metabolism of levodopa at central and peripheral level, however, hampers its therapeutic potential. MAO-B inhibition enhances striatal dopamine activity by means of inhibiting dopamine metabolism, and MAO-B inhibitors are thus used in the treatment of PD, particularly in combination with levodopa. The aim of this study was to design new potent, reversible MAO inhibitors with selectivity towards MAO-B for the symptomatic treatment of PD. Recent studies have shown that C5-substituted phthalide derivatives are highly potent inhibitors of human MAO-B. Phthalide derivatives were also found to be potent inhibitors of human MAO-A. The structural similarity between phthalide and 3-coumaranone suggests that 3-coumaranone may be a useful scaffold for the design of reversible MAO-B inhibitors. In the present study, 3-coumaranone derivatives were thus synthesised and evaluated as potential MAO-A and MAO-B inhibitors. By reacting 6-hydroxy-3-coumaranone with the appropriate alkylbromide in N,N-dimethylformamide in the presence of potassium carbonate, a series of twenty 3-coumaranone derivatives were synthesised. The structures of the compounds were verified with NMR spectroscopy and mass spectrometry. The purities of the compounds were determined by HPLC analyses. To determine the inhibition potencies, the recombinant human MAO-A and MAO-B enzymes were used, and the inhibition potencies were expressed as IC50 values. The results indicated that the 3-coumaranone derivatives are highly potent MAO-B inhibitors. For example, 9 of the 3-coumaranone derivatives inhibited MAO-B with IC50 values < 0.05 μM, with the most potent inhibitor exhibiting an IC50 value of 0.004 μM. Although the 3-coumaranone derivatives are selective MAO-B inhibitors, some compounds were also potent MAO-A inhibitors with the most potent inhibitor exhibiting an IC50 value of 0.586 μM. The reversibility of MAO-B inhibition by a representative inhibitor was examined by measuring the degree to which the enzyme activity recovers after dialysis of the enzyme-inhibitor complex. Since MAO-B activity was almost completely recovered after dialysis, it may be concluded that the 3-coumaranone derivatives bind reversibly to MAO-B. Lineweaver-Burk plots were constructed to show that the representative 3-coumaranone derivative is a competitive inhibitor of MAO-B. To conclude, the 3-coumaranone derivatives are potent, selective, reversible and competitive inhibitors of MAO-B. These compounds may find application in the treatment of neurodegenerative disorders such as PD. Potent MAO-A inhibitors were also discovered, which suggests that 3-coumaranone derivatives may serve as leads for the design of drugs for the treatment of depression. In addition, 3-coumaranone derivatives which inhibited both MAO-A and MAO-B, may have potential application in the therapy of both PD and depressive illness. / MSc (Pharmaceutical Chemistry), North-West University, Potchefstroom Campus, 2015
662

Synthesis and biological evaluation of 6-substituted coumaranone derivatives and related compounds as monoamine oxidase inhibitors / Adriaan Sarel van Dyk

Van Dyk, Adriaan Sarel January 2014 (has links)
Parkinson’s disease (PD) is an age related neurodegenerative disorder that presents with both motor and non-motor symptoms. The most common pathological characteristic of PD is the loss of the pigmented dopaminergic neurons of the substantia nigra pars compacta (SNpc), with the appearance of intracellular inclusions known as Lewy bodies in the affected neurons. The loss of the SNpc neurons results in a deficiency of dopamine in the nigrostriatal pathway of the brain, and it is this deficiency that is responsible for the motor symptoms of PD. Monoamine oxidase B (MAO-B) is predominantly found in the striatum and is responsible for the oxidative metabolism of dopamine. The first-line treatment of PD is dopamine replacement therapy with levodopa, the metabolic precursor of dopamine. Rapid metabolism of levodopa at central and peripheral level, however, hampers its therapeutic potential. MAO-B inhibition enhances striatal dopamine activity by means of inhibiting dopamine metabolism, and MAO-B inhibitors are thus used in the treatment of PD, particularly in combination with levodopa. The aim of this study was to design new potent, reversible MAO inhibitors with selectivity towards MAO-B for the symptomatic treatment of PD. Recent studies have shown that C5-substituted phthalide derivatives are highly potent inhibitors of human MAO-B. Phthalide derivatives were also found to be potent inhibitors of human MAO-A. The structural similarity between phthalide and 3-coumaranone suggests that 3-coumaranone may be a useful scaffold for the design of reversible MAO-B inhibitors. In the present study, 3-coumaranone derivatives were thus synthesised and evaluated as potential MAO-A and MAO-B inhibitors. By reacting 6-hydroxy-3-coumaranone with the appropriate alkylbromide in N,N-dimethylformamide in the presence of potassium carbonate, a series of twenty 3-coumaranone derivatives were synthesised. The structures of the compounds were verified with NMR spectroscopy and mass spectrometry. The purities of the compounds were determined by HPLC analyses. To determine the inhibition potencies, the recombinant human MAO-A and MAO-B enzymes were used, and the inhibition potencies were expressed as IC50 values. The results indicated that the 3-coumaranone derivatives are highly potent MAO-B inhibitors. For example, 9 of the 3-coumaranone derivatives inhibited MAO-B with IC50 values < 0.05 μM, with the most potent inhibitor exhibiting an IC50 value of 0.004 μM. Although the 3-coumaranone derivatives are selective MAO-B inhibitors, some compounds were also potent MAO-A inhibitors with the most potent inhibitor exhibiting an IC50 value of 0.586 μM. The reversibility of MAO-B inhibition by a representative inhibitor was examined by measuring the degree to which the enzyme activity recovers after dialysis of the enzyme-inhibitor complex. Since MAO-B activity was almost completely recovered after dialysis, it may be concluded that the 3-coumaranone derivatives bind reversibly to MAO-B. Lineweaver-Burk plots were constructed to show that the representative 3-coumaranone derivative is a competitive inhibitor of MAO-B. To conclude, the 3-coumaranone derivatives are potent, selective, reversible and competitive inhibitors of MAO-B. These compounds may find application in the treatment of neurodegenerative disorders such as PD. Potent MAO-A inhibitors were also discovered, which suggests that 3-coumaranone derivatives may serve as leads for the design of drugs for the treatment of depression. In addition, 3-coumaranone derivatives which inhibited both MAO-A and MAO-B, may have potential application in the therapy of both PD and depressive illness. / MSc (Pharmaceutical Chemistry), North-West University, Potchefstroom Campus, 2015
663

P53 suppresses expression of the 14-3-3gamma oncogene

Radhakrishnan, Vijayababu, Putnam, Charles, Qi, Wenqing, Martinez, Jesse January 2011 (has links)
BACKGROUND:14-3-3 proteins are a family of highly conserved proteins that are involved in a wide range of cellular processes. Recent evidence indicates that some of these proteins have oncogenic activity and that they may promote tumorigenesis. We previously showed that one of the 14-3-3 family members, 14-3-3gamma, is over expressed in human lung cancers and that it can induce transformation of rodent cells in vitro.METHODS:qRTPCR and Western blot analysis were performed to examine 14-3-3gamma expression in non-small cell lung cancers (NSCLC). Gene copy number was analyzed by qPCR. P53 mutations were detected by direct sequencing and also by western blot. CHIP and yeast one hybrid assays were used to detect p53 binding to 14-3-3gamma promoter.RESULTS:Quantitative rtPCR results showed that the expression level of 14-3-3gamma was elevated in the majority of NSCLC that we examined which was also consistent with protein expression. Further analysis of the expression pattern of 14-3-3gamma in lung tumors showed a correlation with p53 mutations suggesting that p53 might suppress 14-3-3 gamma expression. Analysis of the gamma promoter sequence revealed the presence of a p53 consensus binding motif and in vitro assays demonstrated that wild-type p53 bound to this motif when activated by ionizing radiation. Deletion of the p53 binding motif eliminated p53's ability to suppress 14-3-3gamma expression.CONCLUSION:Increased expression of 14-3-3gamma in lung cancer coincides with loss of functional p53. Hence, we propose that 14-3-3gamma's oncogenic activities cooperate with loss of p53 to promote lung tumorigenesis.
664

Hur påverkar kosten symptom hos barn med ADHD? / How does diet affect symptoms for children with ADHD?

Hector, Johanna, Persson, Marie January 2016 (has links)
Inledning: Drygt 5% av barn i Sverige har en uppmärksamhets- och hyperaktivitetsstörning/ Attention Deficit Hyperactivity Disorder(ADHD), och runt 75% av dem medicineras för att minska symptomen av ADHD. Hyperaktivitet, svårigheter att fokusera och koncentrera sig, och impulsivt beteende är några karaktärsdrag hos barn med ADHD. Syfte: Syftet med litteraturöversikten är att se om det finns kostrelaterade behandlingskomplement för att lindra ADHD hos barn. Metod: En litteraturöversikt där tio vetenskapliga originalartiklar har analyserats och delats upp i fyra olika teman. Resultat: En elimineringskost där vissa födoämnen uteslutadess, ett minskat intag av tillsatser (konstgjorda färgämnen och konserveringsmedel) eller ökat intag av omega-3 visade positiva effekter hos en grupp barn med ADHD där symptomen minskade, speciellt hyperaktivitet. Diskussion: Trots att resultaten av studierna visar en positiv effekt hos vissa barn med ADHD så behövs mer grundlig forskning angående elimineringskost, tillsatser och omega-3. Studierna baseras ofta på frågeformulär som fylls i av föräldrarna vilket kan leda till subjektiva resultat som tar bort generaliserbarheten av studierna. De positiva effekterna antyder att komplementära behandlingsmetoder kan finnas genom en förändrad kost, som förbättrar livskvaliteten och minskar biverkningar hos barn med ADHD och samtidigt sänker kostnaderna för samhället. / Introduction: About 5% of all children in Sweden are diagnosed with Attention Deficit Hyperactivity Disorder (ADHD) and about 75 % get medication do reduce symptoms. Hyperactivity, difficulties to focus and concentrate and impulsive behavior are typical characteristics for children with ADHD. Aim: The aim with this literature review is to see if complementary treatments based on diet can assist to reduce symptoms of ADHD for children. Method: A literature review that analyses ten original articles which are divided into four different topics. Result: An elimination diet that excludes certain foods, reduced intake of food additives and preservatives or increased intake of omega-3 showed positive effects for a group of children with ADHD as symptoms minimized especially for hyperactivity. Discussion: Even though results of the studies show positive effects for certain children with ADHD, more research is needed that further investigates the effects of elimination diet, food additives and omega-3. The studies were mainly based on questionnaires, filled in by parents, which can lead to subjective results. The positive effects suggest that alternative treatments by changed diet might assist children with ADHD, improving life quality and reducing medication side effects together with reduced costs for society.
665

Högläsningens effekter på elevers läsförmåga : En kvalitativ studie om lärares syn på högläsning och hur de använder den i undervisningen / Read-aloud effects on pupils' reading skills : A qualitative study about teachers’ view on the effects of read-alouds and how they use it in practice

Augustsson, Mikaela January 2016 (has links)
Syftet med studien är att undersöka hur lärare använder sig av högläsning i undervisning för att främja elevernas läsförmåga och hur detta syns i elevernas aktiviteter. Teorin som studien bygger på är det sociokulturella perspektivet med ursprung i Lev Vygotskijs teorier om lärande, utveckling och språk. I studien har fem lärare som arbetar i årskurserna F–3 blivit intervjuade med en semistrukturerad intervju. Lärarna har även blivit observerade under en av sina högläsningslektioner för att se hur de använder sig av högläsning för att utveckla elevernas läsförmåga. Resultatet visar att lärarna försöker använda sig av högläsning dagligen i sin undervisning då de anser att den ger väldigt mycket. Lärarna anser att högläsningen utvecklar elevernas ordförråd, läsförståelse, läslust och koncentrationsförmåga. Utifrån observationerna, tidigare forskning och lärarnas intervjuer visar resultatet även att lärarna använder sig av olika arbetssätt och metoder för att eleverna ska få möjlighet att utveckla sin läsförmåga. / The purpose of this study is to examine some teachers' view of the effect of read-alouds on the development of pupils' reading skills, as well as the opportunities the pupils get to develop their reading skills in teacher practices of reading aloud. The study is based on the sociocultural perspective originating in Lev Vygotsky theories on learning, development and language. In this study, five teachers working in preschool and grades 1–3 have been interviewed using qualitative interviews. Teachers have also been observed during one of their read-aloud lessons in order to see how they use reading aloud to develop pupils' reading skills. The results show that the teachers try to read aloud daily in their teaching because they find it has great advantages. The teachers believe that reading aloud develops pupils' vocabulary, reading comprehension, love of reading and concentration. Based on previous research, observation and teacher interviews, the results also show that teachers use approaches to and methods for giving their pupils opportunity to develop their reading skills.
666

Handskrift i dagens skola : En studie av lärares och elevers attityder till handskrift och datorskrift i läs- och skrivinlärning / Handwriting in school today : A study of teachers’ and pupils’ attitudes to handwriting and computer writing in literacy education

Olofsson, Linda January 2016 (has links)
The aim of this study is to investigate how teachers and primary school pupils view the use of handwriting in literacy tuition and what their thoughts are on the future of handwriting. In the study, handwriting is compared to today’s digital ways of writing. The study sets out from the Swedish curriculum (Lgr 11) and is based on interviews with teachers and pupils in grades 1–3. The results show that the pupils tend to see handwriting mainly from an individual perspective and that they consider it to be important knowledge in adult and professional life. The teachers in the study view handwriting from a pedagogical perspective and focus mainly on its role in literacy tuition. In contrast to the pupils involved in the study, the teacher are uncertain regarding the future of handwriting.
667

Prevalent and differential herpesviral gene regulation mediated by 3'-untranslated regions

McClure, Lydia Virginia 16 September 2014 (has links)
Herpesviral infections are currently incurable and are associated with severe human diseases, such as cancer. Kaposi’s Sarcoma-associated Herpesvirus (KSHV), like all herpesviruses, undergoes a long-term, latent infection where few viral products are made as a mechanism to evade the host immune system. Recently, the KSHV latent genome was shown to have bivalent histone marks thought to keep the virus poised for replication. However, it is unclear how the virus prevents spurious leaky transcription from this primed state. The 3' untranslated region (3'-UTR) of transcripts is a common site of gene expression regulation, however less than half of the KSHV 3'-UTRs have been mapped and few studies have interrogated their role during infection. The work presented here is the first large-scale map and analysis of the KSHV 3'-UTRs. Four methods were used to identify the 3'-UTRs expressed by the ~85 KSHV genes, including prediction algorithms, 3'-RACE, DNA tiling array, and next generation deep sequencing analysis. The role of each KSHV 3'-UTR in gene expression was then examined using luciferase reporter assays and showed a surprising prevalence of negative regulation conveyed during latent infection. Sequential deletions across numerous 3'-UTRs indicated RNA structure is likely involved in this regulation. In addition, several KSHV 3'-UTRs conveyed an increase in translation during lytic infection through enhanced recognition by the cap-dependent translation initiation machinery activated via the MNK1 kinase. A second mechanism of KSHV gene regulation was identified through motifs encoded in the K7 3'-UTR. This work indicated that a previously characterized RNA element and a novel putative hairpin are both partially responsible for negative regulation conveyed by the K7 3'-UTR. We hypothesize that these structural motifs control expression of the K7 transcript by altering its sub-cellular location and/or via RNA stability. This work represents a broad 3'-UTR study that mapped the KSHV 3'-UTRs and is the first large-scale functional analysis of 3'-UTRs from a large genome virus. We have implicated post-transcriptional mechanisms, along with known transcriptional regulation, in viral evasion of the immune response during latency and the escape of viral-mediated host shutoff. These results identify new potential targets for therapeutic intervention of KSHV-associated disease. / text
668

Dualité d'action de la galectine-3 dans la pathophysiologie de l'arthrose

Janelle-Montcalm, Audrée January 2007 (has links)
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
669

Nanocomposites polythiophènes/nanotubes de carbone alignés : élaboration, caractérisations et applications aux supercondensateurs en milieu liquide ionique / Nanocomposites polythiophene/aligned carbon nanotubes : elaboration, characterizations and applications for energy storage (supercapacitors) in Ionic liquid

Lagoutte, Sébastien 22 October 2010 (has links)
Le présent travail a porté sur l’élaboration d’électrodes à base de polymère conducteur et d’un tapis de nanotubes de carbone alignés pour les applications de supercondensateur.Dans la première partie de ce travail, nous avons porté notre attention sur le choix de nos matériaux et nous avons pu déterminer leur comportement électrochimique en milieu liquide ionique. Les deux polymères choisis : le poly(3-méthylthiophène) et le poly(3,4-diméthylthiophène) possèdent des propriétés très différentes en terme de capacitance, de potentiel d’oxydation, de résistance ou de cyclabilité. Afin d’allier ces propriétés entre elles, nous avons réalisé la synthèse de copolymères obtenus par voie électrochimique en milieu liquide ionique aprotique. Cette électro-co-polymérisation nous a permis d’obtenir une large gamme de matériaux aux propriétés variables selon la composition du polymère.Dans la deuxième partie de ce travail, nous avons optimisé la synthèse électrochimique d’un nanocomposite poly(3-méthylthiophène)/nanotubes de carbone alignés en milieu liquide ionique. Les matériaux obtenus offrent la propriété d’être « auto-supportés » et permettent ainsi de s’affranchir de collecteur de courant. La nanostructuration grâce aux nanotubes et l’absence de collecteur de courant nous ont permis d’améliorer d’un facteur 3 la capacitance spécifique de nos électrodes. Une optimisation des conditions d’élaboration des nanocomposites permettent d’atteindre une capacitance de 180F.g-1 dans EMITFSI à 30°C. / The present work concerned the elaboration of electrodes containing electronic conducting polymer and a carpet of aligned carbon nanotubes for supercapacitor applications. In the first part of this work, we put our attention on the choice of our materials and we were able to determine their electrochemical behavior in ionic liquid. Both chosen polymers : poly(3-méthylthiopène) and poly(3.4-diméthylthiophène) possess very diffrent properties in term of capacitance, oxidation potential, resistance or cyclability. In the second part of this work, we optimized the electrochemical synthesis of a nanocomposite poly(3-méthyltiophène)/aligned carbon nanotubes in ionic liquid. The obtained materials offer the property to be "self-supported" and allow using themselves without current collector. And optimization of the conditions of nanocomposites elaboration allows reaching a capacitance of 180 F.g-1 in EMITFSI in 30°C.
670

Vieillissement du tritiure de palladium : caractérisation mécanique, état de l'hélium et modélisation / Ageing of palladium tritide : mechanical characterization, helium state and modelling

Segard, Mathieu 29 November 2010 (has links)
Le palladium est couramment utilisé pour le stockage du tritium, isotope radioactif de l’hydrogène, car il forme un tritiure réversible, à basse pression d’équilibre. La décroissance du tritium en hélium-3 provoque un vieillissement du tritiure, caractérisé notamment par l’apparition de bulles d’hélium-3, qui est étudié ici. De précédents travaux de modélisation du vieillissement avaient abouti à la création de deux modèles traitant, d’une part, de la germination des bulles d’hélium-3 (utilisation d’un automate cellulaire) et, d’autre part, de la croissance des bulles (mécanique des milieux continus). Ces modèles étaient fonctionnels, mais leur utilisation était limitée par le manque de données expérimentales d’entrée et de recalage. Ce travail de thèse a donc consisté à acquérir les données expérimentales les plus pertinentes pour améliorer la modélisation du vieillissement du tritiure de palladium. La première partie de ce travail a consisté à estimer les propriétés mécaniques du tritiure de palladium (limite d’élasticité, contrainte maximale, loi de comportement…), déduites de celles de l’hydrure et du deutérure de palladium, mesurées à l’aide d’essais de traction in situ. En seconde partie, la caractérisation du vieillissement a été entreprise, focalisée sur des observations de bulles dans le tritiure de palladium par microscopie électronique en transmission, des mesures de pression à l’intérieur des bulles par résonance magnétique nucléaire et des mesures de gonflement macroscopique du matériau par pycnométrie. Ces travaux ont conduit à des avancées significatives quant à la compréhension du vieillissement et ont permis d’améliorer considérablement sa modélisation. / Palladium is commonly used for the storage of tritium (the hydrogen radioactive isotope), since it forms a low-equilibrium-pressure and reversible tritide. Tritium decay into helium-3 is responsible for the ageing of the tritide, leading to the apparition of helium-3 bubbles for instance. Both experimental and theoretical aspects of this phenomenon are studied here.Previous works on ageing modelling led to two main models, dealing with:- Helium-3 bubbles nucleation (using a cellular automaton),- Bubbles growth (using continuum mechanics).These models were quite efficient, but their use was limited by the lack of input data and fitting experimental parameters.To get through these limitations, this work has consisted in studying the most relevant experimental data to improve the modelling of the palladium tritide ageing.The first part of this work was focused on the assessment of the mechanical properties of the palladium tritide (yield strength, ultimate strength, mechanical behaviour…). They were deduced from the in situ tensile tests performed on palladium hydride and deuteride.In the second part, ageing characterization was undertaken, mainly focusing on:- Bubbles observations in palladium tritide using transmission electron microscopy,- Internal bubble pressure measurements using nuclear magnetic resonance,- Macroscopic swelling measurements using pycnometry.The present work has led to significant progress in ageing understanding and has brought very valuable improvements to the modelling of such a phenomenon.

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