L'enzynle HSD3B2 humaine et la protéine STAR de souris encodées par les gènes HSD3B2 et Star, respectivement, sont retrouvées principalement au niveau des gonades et surrénales. L'importance de STAR comme transporteur du cholestérol et de HSD3B2 comme enzyme de la stéroïdogenèse est lnise en évidence par des mutations de ces gènes causant une hyperplasie congénitale des surrénales, un pseudohermaphrodisme mâle et une insuffisance des surrénales. Un rôle pour la famille de récepteurs nucléaires orphelins NUR 77 dans la stéroïdogenèse a été considéré. En effet, NUR77 est présent dans les gonades et surrénales où son expression est fortement et rapidement induite par des horlnones qui activent certains gènes impliqués dans la stéroïdogenèse. De plus, les profils d'expression de Nur77 et des gènes RSD3B2 et Star sont corrélés. Lors de cette thèse, j'ai démontré que les promoteurs HSD3B2 et Star constituent des nouvelles cibles de NUR77. Des éléments de réponse localisés à -130 pb et -95 pb des promoteurs HSD3B2 et Star respectivement, sont essentiels et suffisants pour conférer une réponse dépendante de NUR77, et la mutation de ces élélnents . diminue leurs activités basale et homlono-dépendante dans les cellules stéroïdogéniques. Dans les cellules de Leydig, un réduction de l'expression de Nur77 par siARN réduit l'induction de l'expression de Star par l'AMPc. Également, NUR77 coopère avec des co activateurs de la famille SRC et avec des membres de la famille AP-1 dans la régulation des promoteurs RSD3B2 et Star, respectivement. De plus, le dexaméthasone, un glucocorticoïde synthétique, inhibe l'activation de Star en diminuant le recrutement de NUR77, et non SF-I, à la région proximale du promoteur Star, donnant un argument moléculaire à la suppression causée par le stress de la production de testostérone dans le testicule. J'ai démontré que la voie de signalisation des CaMK est requise pour l'expression de STAR et NUR77 en réponse à l'AMPc dans les cellules de Leydig. Ainsi, CaMKI est spécifiquement exprimé dans les cellules de Leydig. Enfin, je démontre que CaMKI coopère avec NUR 77 et MEF2 pour activer les promoteurs Star et Nur77, respectivement, dans ces cellules. Ainsi, l'identification de NUR 77 comme régulateur important des promoteurs HS1J3B2 et Star et de son mécanisme d'action aident à mieux défénir la spécificité tissulaire et la régulation hormonale de ces gènes dans les cellules de Leydig en plus de soulever un rôle pour CaMKI dans ce processus.

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Made available in DSpace on 2015-05-14T13:00:13Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2275378 bytes, checksum: fcb4196c739d83997818dc074daf738f (MD5) Previous issue date: 2010-03-11 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The pharmacological effects of carvacrol, a monoterpenoid phenol, on the cardiovascular system were studied in normotensive rats, using in vivo and in vitro techniques. In superior mesenteric artery rings isolated from rats with functional endothelium carvacrol (10-8 - 3 ₓ 10-4 M) concentration-dependently relaxed phenylephrine-induced contractions (pD2 = 4.59  0.02, MR = 103.03  1.5%, N=8) and this effect was not altered after removal of the endothelium (pD2 = 4.36  0.02, MR = 111.03  4.8%, N=8), suggesting that the vasorelaxant response induced by carvacrol appears to be independent of vascular endothelium. Furthermore, carvacrol antagonized the vasoconstriction induced by high K+ solution (Tyrode with 80 mM of KCl) (pD2 = 4.12  0.01, MR = 94.38  3.97%, N=6), inhibited contraction elicited by CaCl2 in depolarizing (KCL 60 mM) nominally without Ca2+ medium out carvacrol also antagonized the contractions induced by the L-type Ca2+ channel agonist, S(-)-Bay K 8644 (pD2 = 4.537  0.023, MR = 9.8  3.58%, N=6), indicating that the vasodilatation involve probably the inhibition of Ca2+ influx through L-type voltage-dependent calcium channels (Cav type-L). Additionally, carvacrol antagonized the contractions induced by CaCl2 in nominally without Ca2+ medium in the presence of PHE and nifedipine, suggesting a possible inhibition of calcium influx by store operated channels (SOC), receptor operated channels (ROC) and/or TRP channels. Interestingly, in a depolarizing (KCL 60 mM) nominally without Ca2+ medium and in the presence of nifedipine, carvacrol also inhibited the contraction induced by CaCl2, suggesting a probable inhibition of SOC and/or TRP channels. To evaluate the involvement of TRP channels in the vasorelaxant effect induced by carvacrol, non-selective inhibitors were used. No change in the relaxation response was observed in the presence of ruthenium red (pD2= 4.31  0.029, N=6), however, the effect induced by carvacrol was potentiated by La3+ (pD2 = 5.231  0,04, N=6), Gd3+ (pD2 = 4.97  0.02, N=6) or Ni2+ (pD2 = 5.079  0.02, N=6), furthermore, Mg2+ (pD2 = 4.168  0.021; MR = 81.12  4.03%, N=6) attenuated the relaxation elicited by carvacrol, suggesting that monoterpenoid may to action on TRPC1, TRPC3, TRPC6 and TRPM7 channels. Carvacrol also induced hypotension and bradycardia in non-anesthetized normotensive rats. In conclusion, these results suggest that carvacrol induced vasorelaxant effect in superior mesenteric artery rats isolated probably inhibiting Ca2+ influx by Cav, SOC (TRPC1), ROC (TRPC1 or TRPC6) and TRPM7 channels. Moreover, the effects induced by carvacrol in normotensive non-anesthetized rats showed a hypotensive and bradycardic activity. / Os efeitos farmacológicos de carvacrol, um fenol monoterpenóide, sobre o sistema cardiovascular, foi estudado em ratos normotensos, usando técnicas in vivo e in vitro. Carvacrol (10-8 - 3 ₓ 10-4 M) induziu vasorelaxamento dos anéis de artéria mesentérica superior isolada de rato pré-contraídos com 10 μM FEN (pD2 = 4,59  0,02, Emáx = 103,03  1,5%) na presença do endotélio funcional e esse efeito não foi alterado após a remoção do endotélio (pD2 = 4,36  0,02, Emáx = 111,03  4,8%), sugerindo, portanto, que a resposta vasorelaxante induzida por carvacrol parece ser independente do endotélio vascular. Interessantemente em anéis pré-contraídos com KCl 80 mM (pD2 = 4,12  0,01, Emáx = 94,38  3,97%), observou-se uma diminuição na sua potência e na sua eficácia farmacológica, sugerindo um passo comum na via que seria um aumento citosólico dos níveis de cálcio. Adicionalmente, carvacrol antagonizou, de maneira dependente de concentração, as contrações induzidas por CaCl2 em meio despolarizante nominalmente sem Ca2+ e induziu relaxamento das contrações induzidas pelo S(-)-Bay K 8644 (pD2 = 4,537  0,023, Emáx = 91,8  3,58%) com uma diminuição na sua eficácia farmacológica, sugerindo uma inibição do influxo de cálcio por canais de Ca2+ tipo-L. Além disso, antagonizou as contrações induzidas por CaCl2 em meio nominalmente sem cálcio, na presença de FEN e nifedipina, sugerindo uma provável inibição do influxo de cálcio por SOC, ROC e/ou canais TRP. Como também, em um meio despolarizante e nominalmente sem cálcio na presença de nifedipina esse mesmo antagonismo foi observado, ressaltando a provável inibição dos SOC e/ou canais TRP. Para avaliar a participação dos canais TRP, as preparações foram incubadas com La3+ (pD2 = 5,231  0,04) , Gd3+ (pD2 = 4,97  0,02) e Ni2+ (pD2 = 5,079  0,02) onde seu efeito foi potencializado sugerindo sua ação sobre os canais TRPC e ao utilizar magnésio (pD2 = 4,168  0,021 e Emáx = 81,12  4,03%) tanto sua potência quanto sua eficácia farmacológica foi atenuada, sugerindo inibição do canal TRPM7. Nos estudos in vivo, em ratos normotensos não anestesiados, carvacrol produziu hipotensão e bradicardia. Em conclusão, esses resultados sugerem que carvacrol induz efeito vasorelaxante em anéis de artéria mesentérica superior isolada de rato por inibir provavelmente TRPM7, como também inibir o influxo de cálcio por Cav, SOC, ROC e ou TRPC1 e 6. Além disso, os efeitos induzidos por carvacrol em ratos normotensos não anestesiados mostrou uma atividade hipotensora e bradicárdica.

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Dans le néocortex murin, la division des cellules précurseurs a lieu dès le stade E11 et donne naissance aux premiers neurones pionniers dont les cellules de Cajal-Retzius. L'activité électrique spontanée, portée par les canaux ioniques, joue un rôle prépondérant dans le développement du système nerveux central. Comprendre la place des canaux ioniques et de la signalisation calcique dans les phases précoces de le neurogenèse était l'objectif principal de mon projet. Nous avons montré l'apparition précoce de canaux sodiques dépendants du voltage dans 55% des cellules neuronales à E13, dont les cellules de Cajal-Retzius. En parallèle, nous avons observé des activités calciques spontanées dans les cellules proliférantes et neuronales au même stade. La conception d'un logiciel d'imagerie nous a permis d'analyser statistiquement ces activités et d'identifier les canaux ioniques impliqués. Alors que les synapses ne sont pas encore formées, nous avons observé la mise en place d'activités synchrones au sein du néocortex et démontré l'existence de communications paracrines entre les cellules. De plus, nous avons identifié l'existence d'une cascade de signalisation où la dépolarisation des récepteurs glycinergiques active les canaux sodiques présents sur les neurones pionniers. Dans ces neurones, l'influx sodique entraîne une augmentation de calcium cytoplasmique via un échangeur Na+/Ca2+ puis une exocytose glutamatergique dont le libération paracrine induit l'activation d'autres cellules néocorticales. L'utilisation de la culture organotypique de cerveau nous a laissé entrevoir une implication physiologique majeure de cette cascade de signalisation dans la corticogenèse.

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M.Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / In the present study, the removal of Ca2+ and Mg2+ from cooling tower water using Amberlite IR120 and Amberjet 1200 was studied by the application of one factor at a time method (OFAT) and response surface modelling (RSM). The effect of operational parameters such as contact time (min), pH, dosage (mL), concentration (mg/L) and temperature (K) were investigated using central composite design. The regeneration of the Amberlite IR120 and Amberjet were also studied. The purpose of the study was to apply OFAT and RSM to investigate and optimize the ion exchange operating parameters. Furthermore, the second-order empirical model that was developed, using the analysis of variance (ANOVA), presented a sufficient correlation to the ion exchange experimental data. The optimal ion exchange operating conditions for Amberlite IR120 and Amberjet 1200 were found to be: contact time was 120 min, dosage of 150mL, initial pH level of 2, concentration of 400mg/L and temperature of 343K. Regeneration of Amberlite IR120 and Amberjet 1200 using 0.5 M NaCl stripping solution initially showed an increase in % Ca2+ and Mg2+ removal, then a decrease in subsequent cycles. The correlation coefficients (R2) of Langmuir, Freudlich and Tempkin isotherms were found to range from 0.92 to 1 and this suggest that experimental data best described the models. However correlation coefficients (R2) for Dubinin–Radushkevich (D-R) model were found to range between 0.5 to 0.8 and this means that experimental data does not fit the model. Thermodynamic functions such as entropy (Δ𝑆𝑜), enthalpy (Δ𝐻𝑜) and change of free energy (Δ𝐺𝑜) were obtained from the gradient and intercepts of straight line graphs. The positive values of ΔG° were found meaning that the adsorption is not spontaneous and positive values of ΔH° were found meaning the endothermic type of adsorption which indicate the chances of physical adsorption.The correlation coefficient (R2) values of pseudo-first-order, pseudo-second-order and intraparticle models were found to range from 0.89 to 1 on both metals as shown in table 4.4. This observation clearly indicates that pseudo-first-order, pseudo-second-order and intraparticle diffusion models best describe the experimental data in the removal Ca2+ and Mg2+ from cooling tower water.

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