Global ETD Search

1	Hyperactivation in human semen and sperm subpopulations by selected calcium modulators Ntanjana, Nomfundo January 2014 (has links) Magister Scientiae (Medical Bioscience) - MSc(MBS) / A functional sperm is critical for successful fertilization in order to deliver an intact genome to the site of fertilization. It is often characterized by high motility and normal morphology. Moreover, sperm hyperactivated motility is imperative for both detachment from the oviductal wall and for penetration into the zona pellucida, subsequently resulting in fertilization. Several semen parameters such as volume, colour, sperm morphology and sperm concentration are used to clinically discriminate between fertile and sub-fertile males. Additionally, several sperm functional tests assess sperm function and a male’s fertility potential. A sperm feature that is not currently assessed clinically, but could possibly discriminate between fertility and infertility, is hyperactivation. The aim of this project was to investigate motility degrees (good, medium and poor) of sperm subpopulations and induce hyperactivation in each subpopulation, as well as to sperm in semen, by addition of caffeine and procaine. This was achieved by separating three sperm subpopulations from a semen sample using the Puresperm density gradient separating technique. Sperm subpopulations were exposed to 5mM caffeine and 2 mM procaine respectively for 15, 30, 60, 90 and 120 minutes. Sperm in semen was exposed to caffeine and procaine using a flush technique and analysed at 0, 5, 15, 30, 45 and 60 minutes. Sperm displaying hyperactivation was determined using cut-offs for curvilinear velocity, linearity and amplitude of lateral head displacement. The results indicate significant differences in overall percentage motility, sperm kinematic parameters and hyperactivation among the three subpopulations (p<0.05). Procaine and caffeine both induced hyperactivation in subpopulations, although the most pronounced effect of procaine was evident after 15-30 minutes compared to caffeine (60-90 minutes) in subpopulations. Maximum hyperactivation of sperm in semen was seen after 15- 30 minutes in both procaine and caffeine. Moreover, caffeine had significantly higher stimulating effect than procaine. The results suggest that the existence and distinct motility characteristics of subpopulations should be considered in future during clinical assessment of male fertility, especially when assessing hyperactivation. The immediate and higher stimulation response of sperm with the flush technique indicates that the technique may be an ideal sperm functional test compared to the separation technique. The separation technique may be used to categorize sperm subpopulation of a patient in terms of motility (high motile or low motile) and to stimulate such subpopulations with chemicals for use in assisted reproduction technologies. Hyperactivation Sperm motility Sperm subpopulations Calcium modulators
2	Molecular Pathways Involved in Stallion Sperm Capacitation Vivani, Leticia 01 January 2011 (has links) (PDF) After ejaculation, mammalian spermatozoa must undergo a series of complex and poorly understood cellular events known as “capacitation” in order to be able to fertilize an oocyte. Among these, biochemical changes such as an increase in tyrosine phosphorylation of some sperm proteins have been correlated with the sperm capacity to fertilize an egg and found to be regulated by a cAMP dependent pathway. The influx of ions such as Ca2+ and HCO3- induce the activation of a soluble adenylyl cyclase (SACY) increasing the cAMP levels within the cell that leads to the activation of a protein kinase A (PKA), and a subsequent increase in protein tyrosine phosphorylation. This modification in sperm proteins seems to be essential for induction of a change in the motility pattern known as hyperactivation that enables the sperm to penetrate the zona pellucida of the oocyte and initiate fertilization. Since PKA is a serine/threonine kinase, it is not clear how it mediates protein tyrosine phosphorylation during sperm capacitation. Based on the finding that in somatic cells PKA activates c-Src, it has been proposed that the Src family of protein kinases (SFK) are the intermediate players involved in tyrosine phosphorylation induced by PKA activity. In order to better understand the molecular mechanisms involved in stallion sperm capacitation, the objectives of our study were: (1) To analyze PKA activity during stallion sperm capacitation (2) To evaluate the involvement of the Src family of protein kinases (SFK) on stallion sperm phosphorylation events associated with capacitation. Standard In Vitro Fertilization (IVF) has not been reproducibly successful in the horse. Recent data indicate that good fertilization rates may be achieved after treatment of sperm with procaine to induce hyperactivation. Our objectives were also to determine if drugs used in other species as well as procaine induce hyperactivation in stallion sperm and to evaluate biochemical changes such as protein tyrosine phophorylation. horse sperm pathway capacitation hyperactivation Biotechnology
3	Rôle du CD46 dans le développement et la fonction des lymphocytes T régulateurs naturels Darwiche, Jinane January 2006 (has links) No description available. CD47 Lymphocytes T régulateurs naturels Immunorégulation Hyperactivation lymphocytaire
4	Developing Viral Strategies to Study mTOR and its Regulators as Mediators of Epileptogenesis Gulati, Ruhi 04 November 2019 (has links) No description available. Neurology Epilepsy mTOR hyperactivation mTOR stereotaxic surgery PTEN
5	Seasonal differences in semen characteristics and sperm functionality in Tankwa goats Ngcauzele, Asanele January 2018 (has links) Magister Scientiae (Medical Bioscience) - MSc(MBS) / Tankwa goats have been free-ranging in the Tankwa Karoo National Park in the Northern Cape for more than 80 years. A genetic study concluded that these feral goats are a unique genetic resource compared to other goat breeds in South Africa and should be conserved as a distinctive population. A decision taken by the South African National Parks who is the managing authority in the park, was to remove all alien species, which included the Tankwa goats. Several animals were translocated to the Carnarvon Research Station by the Northern Cape Department of Agriculture, Land Reform & Rural Development, where the Tankwa goat population has grown to a few hundred individuals. Currently, sound scientific decisions including the application of a wide range of technologies and approaches are applied to conserve the population, such as an informed understanding of the reproductive biology of these goats. The aim of this study was to define sperm quality in Tankwa goats using various macroscopic and microscopic evaluation techniques. Tankwa indigenous goat Sperm motility Sperm morphology Hyperactivation Computer-aided sperm analysis (CASA)
6	Alterações semelhantes à capacitação no sêmen bovino após a criopreservação utilizando diluidores a base de gema de ovo ou lecitina de soja / Capacitation-like changes in bovine semen after cryopreservation using extenders within egg yolk or soy lecithin Zaffalon, Fabiane Gilli 11 December 2009 (has links) O objetivo deste estudo foi avaliar os efeitos de três diluidores diferentes na criopreservação do sêmen bovino sobre a motilidade, hiperativação espermática, reação acrossomal, capacitação e peroxidação lipídica das membranas espermáticas. Foram realizadas seis colheitas de sêmen em intervalos quinzenais de dez touros zebuínos da raça Nelore. O sêmen in natura foi avaliado, dividido em três tratamentos: uma fração foi diluída em meio a base de gema de ovo (Botu-Bov® - diluidor 1), a segunda fração diluída em meio a base de lecitina de soja (Botu-Bov® - diluidor 2) e a terceira fração em meio AndroMed® (diluidor 3) também a base de lecitina de soja. Logo após as amostras foram submetidas à congelação. As avaliações do sêmen após descongelação consistiram na análise computadorizada das características de motilidade e nas análises pela citometria de fluxo quanto à reação acrossomal (PI/FITC-PSA/H33342); peroxidação lipídica (PI/C11-BODIPY581/591/H33342) e capacitação espermática através da estabilidade da membrana plasmática (Merocianina 540/Yo-Pro1/H33342). As variáveis foram submetidas à análise de variância e ao teste LSD para comparação das médias, ao nível de 5% de significância. O diluidor a base de gema de ovo preservou melhor a motilidade espermática, a população de células com integridade de membrana plasmática e acrossomo não reagido no sêmen bovino pós-descongelação que os diluidores a base de lecitina de soja. Os espermatozóides criopreservados com o diluidor a base de gema de ovo apresentou menor sub população de células hiperativas e com membrana plasmática desestabilizada quando comparados com os diluidores a base de lecitina de soja e o diluidor a base de gema de ovo possibilitou uma diminuição da peroxidação lipídica das membranas espermáticas / The objective of this experiment was evaluate the effects of three diferent extenders in bovine semen cryopreservation about motility, sperm hiperactivation, acrosome reaction, capacitation, and sperm membrane lipid peroxidation. It was made six collection of semen samples each 15 days of 10 Nelore bulls. Semen samples in natura was verify and divided in three treatments: The first one was extended in egg yolk base (Botu-Bov® Extender 1), second one was extended in soy lecithin base (Botu-Bov® Extender 2) and the third was extended in AndroMed® soy lecithin base too. After that, semen samples were submitted to freeze process. Semen evaluations after thawing were made with computer assisted sperm analysis (CASA) and flow citometry for acrosome reaction (PI/FITC-PSA/H33342), lipid peroxidation (PI/C11-BODIPY581/591/H33342) and sperm capacitation by plasma membrane stability (Merocianina 540/Yo-Pro1/H33342). Data obtained from experimental proceeding were submitted to variance analysis and LSD test to compare means with 5% of significance. Egg yolk base extender preserved better sperm motility, cell population with plasma membrane integrity and non-reacted acrosome in bovine semen after thawing than soy lecithin extenders. Cryopreserved sperm with egg yolk base extender displayed less subpopulation of hiperactivated cells, less destabilized plasma membrane and permitted a decrease of lipid peroxidation of membranes when it was compared with soy lecithin extender Acrosome reaction Bull Cryopreserved semen Diluidores Extender Hiperativação Hyperactivation Reação acrossomal Sêmen criopreservado Touro
7	Alterações semelhantes à capacitação no sêmen bovino após a criopreservação utilizando diluidores a base de gema de ovo ou lecitina de soja / Capacitation-like changes in bovine semen after cryopreservation using extenders within egg yolk or soy lecithin Fabiane Gilli Zaffalon 11 December 2009 (has links) O objetivo deste estudo foi avaliar os efeitos de três diluidores diferentes na criopreservação do sêmen bovino sobre a motilidade, hiperativação espermática, reação acrossomal, capacitação e peroxidação lipídica das membranas espermáticas. Foram realizadas seis colheitas de sêmen em intervalos quinzenais de dez touros zebuínos da raça Nelore. O sêmen in natura foi avaliado, dividido em três tratamentos: uma fração foi diluída em meio a base de gema de ovo (Botu-Bov® - diluidor 1), a segunda fração diluída em meio a base de lecitina de soja (Botu-Bov® - diluidor 2) e a terceira fração em meio AndroMed® (diluidor 3) também a base de lecitina de soja. Logo após as amostras foram submetidas à congelação. As avaliações do sêmen após descongelação consistiram na análise computadorizada das características de motilidade e nas análises pela citometria de fluxo quanto à reação acrossomal (PI/FITC-PSA/H33342); peroxidação lipídica (PI/C11-BODIPY581/591/H33342) e capacitação espermática através da estabilidade da membrana plasmática (Merocianina 540/Yo-Pro1/H33342). As variáveis foram submetidas à análise de variância e ao teste LSD para comparação das médias, ao nível de 5% de significância. O diluidor a base de gema de ovo preservou melhor a motilidade espermática, a população de células com integridade de membrana plasmática e acrossomo não reagido no sêmen bovino pós-descongelação que os diluidores a base de lecitina de soja. Os espermatozóides criopreservados com o diluidor a base de gema de ovo apresentou menor sub população de células hiperativas e com membrana plasmática desestabilizada quando comparados com os diluidores a base de lecitina de soja e o diluidor a base de gema de ovo possibilitou uma diminuição da peroxidação lipídica das membranas espermáticas / The objective of this experiment was evaluate the effects of three diferent extenders in bovine semen cryopreservation about motility, sperm hiperactivation, acrosome reaction, capacitation, and sperm membrane lipid peroxidation. It was made six collection of semen samples each 15 days of 10 Nelore bulls. Semen samples in natura was verify and divided in three treatments: The first one was extended in egg yolk base (Botu-Bov® Extender 1), second one was extended in soy lecithin base (Botu-Bov® Extender 2) and the third was extended in AndroMed® soy lecithin base too. After that, semen samples were submitted to freeze process. Semen evaluations after thawing were made with computer assisted sperm analysis (CASA) and flow citometry for acrosome reaction (PI/FITC-PSA/H33342), lipid peroxidation (PI/C11-BODIPY581/591/H33342) and sperm capacitation by plasma membrane stability (Merocianina 540/Yo-Pro1/H33342). Data obtained from experimental proceeding were submitted to variance analysis and LSD test to compare means with 5% of significance. Egg yolk base extender preserved better sperm motility, cell population with plasma membrane integrity and non-reacted acrosome in bovine semen after thawing than soy lecithin extenders. Cryopreserved sperm with egg yolk base extender displayed less subpopulation of hiperactivated cells, less destabilized plasma membrane and permitted a decrease of lipid peroxidation of membranes when it was compared with soy lecithin extender Diluidores Hiperativação Reação acrossomal Sêmen criopreservado Touro Acrosome reaction Bull Cryopreserved semen Extender Hyperactivation
8	Thérapies ciblées dans le mélanome : mécanismes impliqués dans les effets paradoxaux, les résistances et évaluation de nouvelles combinaisons / Targeted therapies in melanoma : mechanisms involved in paradoxal effects, resistance and evaluation of novel combinations Boespflug, Amélie 10 October 2018 (has links) La prise en charge du mélanome métastatique a été bouleversée par les thérapies ciblées comme les inhibiteurs de RAF (RAFi) et les inhibiteurs de MEK (MEKi). Les RAFi permettent dans le mélanome BRAF V600 muté d’améliorer la survie mais leur effet est limité en monothérapie par l’hyperactivation paradoxale de la voie des MAPK dans les cellules non BRAF V600 mutée qui est responsable de l’apparition de mélanomes primitifs induits. Dans ce travail nous montrons la différence entre les modifications transcriptomiques induites par les RAFi dans des lignées cellulaires de mélanome BRAF mutées par rapport à celles induites dans des lignées non BRAF mutées ce qui a permis d’identifier des gènes potentiellement impliqués dans le développement de mélanomes induits. L’efficacité des RAFi est également limitée dans le temps par la survenue de résistances acquises. Nous montrons qu’une charge allélique mutée (CAM) de BRAF V600 élevée est potentiellement associée à une bonne réponse au traitement par RAFi et que la plasticité cellulaire induite par ZEB1 est associée à la résistance aux RAFi. Il n’existe pour le moment pas de thérapie ciblée approuvée dans le mélanome métastatique NRAS muté. Les MEKi sont limités par des résistances qui ne leur ont pas permis d’améliorer significativement la survie des patients. Nous montrons qu’une amplification de NRAS et la mutation MEK P124L sont responsables de résistance aux MEKi dans le mélanome NRAS muté. Nous avons testé le tramétinib (MEKi) en association avec d’autres thérapies ciblées dans des PDX de mélanome NRAS muté afin de mettre en évidence des combinaisons qui améliorent l’efficacité anti tumorale des MEKi dans cette indication / Targeted therapies like RAF inhibitors (RAFi) and MEK inhibitors (MEKi) have completely changed the therapeutic landscape in metastatic melanome. RAFi offer increased survival in patients with BRAF V600 mutated metastatic melanoma but they are limited in their use as single agents by an hyperactivation of the MAPK signaling pathway in non BRAF mutated cells that is responsible for the developpement of treatment induced primary melanomas. In this work we show the differences in the transcriptomic modifications induced by RAF inhibitos in BRAF mutated melanoma cell lines and NRAS mutated cell lines and we identified potential genes implicated in the development of treatment induced melanomas. The anti-tumor efficacity of RAFi is also limited by the acquired resistances that appear after several months of treatment. We show that a high BRAF V600E mutant allelic burden is potentially associated with a good response to RAFi and that ZEB1 induced cell plasticity is responsible for resistance to RAFi. No targeted therapy is approuved for NRAS mutated melanoma. Innate and acquired resistances limit the developpment of MEKi in this setting. We show that NRAS amplification and a MEK P124L mutation are responsible for resistance in NRAS melanoma. Finally, we tested five targeted therapies in combination with trametinib in NRAS mutated PDXs to identify combinations that improve the anti-tumoral effect of MEKi in this setting Mélanome Thérapie ciblée Résistance Hyperactivation paradoxale NRAS BRAF Plasticité Déséquilibre allélique Melanoma Targeted therapy Resistance Paradoxal activation NRAS BRAF Plasticity Allelic imbalance 610
9	Hyperactivations frontales en mémoire de travail dans le trouble cognitif léger Moffat, Nicolas 04 1900 (has links) Des études récentes ont rapporté que les individus âgés avec un trouble cognitif léger (TCL) ont de plus grandes activations en lien avec la réalisation d’une tâche cognitive que des personnes âgées saines. Des auteurs ont proposé que ces hyperactivations pourraient refléter des processus de plasticité cérébrale compensatoires ayant lieu pendant la phase précoce de la maladie d’Alzheimer. Des processus de compensations fonctionnelles pourraient émerger en réponse à une perte d’intégrité structurelle dans les régions du cerveau normalement requises pour compléter une tâche. Dans ce mémoire, j’ai évalué cette hypothèse chez des personnes avec TCL en faisant appel à une tâche de mémoire de travail comportant plusieurs niveaux de difficulté ainsi qu’aux techniques d’imagerie par résonnance magnétique (IRM) structurelle et fonctionnelle. Des analyses de régression multiples ont été utilisées afin d’identifier les régions cérébrales dont l’activité variait en fonction de l’intégrité neuronale telle que définie par le volume de l’hippocampe. Les valeurs estimées des paramètres du signal de ces régions furent ensuite extraites afin de procéder à des analyses corrélationnelles sur la performance ainsi que sur le volume de différentes structures cérébrales. Les résultats indiquent des hyperactivations dans les régions frontales droites chez les participants TCL souffrant d’une plus grande atteinte neuronale. De plus, le niveau d’activation est négativement corrélé au volume de structures frontales et pariétales. Ces résultats indique la présence d’une hyperactivation compensatoire dans la phase du TCL associée à la réalisation d’une tâche de mémoire de travail. / Recent studies have shown greater task-related activation in individuals with mild cognitive impairment (MCI) compared to healthy older adults. It has been suggested that these hyperactivations reflect compensatory processes of brain plasticity in the early phase of Alzheimer’s disease (AD). Functional compensation processes could emerge in response to a loss of structural integrity in brain regions typically required for the task. In this masters dissertation, I examined this hypothesis in MCI using a working memory task that incorporated a parametrical variation of difficulty level as well as functional and structural magnetic resonance imaging (MRI). Multiple regression analyses were used to identify areas of the brain in MCI in which functional activation varied as a function of neural injury as measured by hippocampal volume. Parameter estimates from these areas were then extracted and used for further correlational analyses with performance and structural volumes. Results indicate that MCI participants with high neural injury hyperactivated a subset of regions in the right frontal lobe. Furthermore, the level of activation was negatively correlated with the volume of frontal and parietal regions. These results indicate the presence of compensatory hyperactivations associated with a working memory task in persons with MCI. Maladie d’alzheimer Trouble cognitive léger Fonctions exécutives Processus compensatoires Hyperactivation Imagerie à résonnance magnétique Analyses multimodales Alzheimer’s disease Mild cognitive impairment Executive functions Compensatory mechanisms Magnetic resonance imaging Multimodal analyses
10	Untersuchungen zur kapazitationsassoziierten Signaltransduktion in humanen Spermatozoen und Evaluation des MACS-Verfahrens zur Ejakulataufbereitung Kriegel, Christian 17 May 2013 (has links) (PDF) Als Kapazitation bezeichnet man den im weiblichen Reproduktionstrakt stattfindenden Reifungsschritt, der Spermien das volle Fertilisierungspotential verleiht. Die molekularbiologischen Grundlagen dieses für eine erfolgreiche natürliche oder auch artifizielle Befruchtung essenziellen Prozesses sind bis heute nur unvollständig verstanden. Im Rahmen der vorliegenden Dissertation wurden die mit der Kapazitation einhergehenden funktionellen und strukturellen spermalen Veränderungen untersucht. Die kapazitative Stimulation führte zu einer gesteigerten Motilität bis hin zur Hyperaktivierung, zu einer vermehrt induzierten Akrosomenreaktion und zu einer deutlich reduzierten Apoptoseaktivität. Anhand von Inhibitionsexperimenten wurde die Rolle der potentiellen Signaltransduktoren Caspase-1, Calpain und Calmodulin analysiert. Dabei wies die Calmodulinantagonisierung auf eine ausgeprägte Calciumabhängigkeit aller untersuchten kapazitationsassoziierten Prozesse hin. Die Hemmung von Caspase-1 und Calpain führte zu einer Beeinträchtigung der Motilität und der Akrosomenreaktion ohne das Ausmaß der Apoptoseinduktion zu beeinflussen. Die vorstehend genannten Erkenntnisse wurden zur Evaluation verschiedener Ejakulataufbereitungsprotokolle genutzt. Dabei konnte gezeigt werden, dass die Kombination des modernen Verfahrens der immunomagnetische Zellseparation mit der etablierten Methode der Dichtegradientenzentrifugation dem einfachen Standard in Bezug auf die Anreicherung hochmotiler Spermien mit minimaler Apoptoseaktivität aus frischen wie auch aus kryokonservierten Ejakulaten deutlich überlegen war. Bedeutsam im Hinblick auf eine mögliche pratische Anwendung der immunomagnetischen Zellseparation erscheint der Befund, dass die durch das kombinierte Anreicherungsverfahren erhaltene Spermatozoensubpopulation im Hamsteroozytenpenetrationstest ein signifikant höheres Fertilisierungspotential zeigte. Spermium Kapazitation Apoptose Fertilität immunomagnetische Zellseparation MACS Hamstereizellen Caspase Calpain Calmodulin Caspase-1 Mitochondrium assistierte Reproduktion Ejakulataufbereitung Dichtegradientenzentrifugation Kryokonservierung Motilität Hyperaktivierung Chlortetracyclinfärbung Akrosomenreaktion Akrosom Sperm Capacitation Apoptosis Fertility Immunomagnetic Cellseparation MACS Hamsteroocyte Caspase Calpaine Calmodulin Caspase-1 Mitochondria Assisted Reproduction Ejaculate Density Gradient Centrifugation Cryopreservation Motility Hyperactivation Chlortetracycline Stain Acrosome Reaction Acrosome ddc:610

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