Application of the molluscan neuropeptide FMRFamide to two identified neurones in the cerebral ganglia of Helix aspersa induces quite different effects. In the Cl neurone, FMRFamide produces a slow hyperpolarizing current carried by K+ while with the C2 neurone it causes a fast depolarizing current carried by Na+. Possible mechanisms underlying the slow K+ response were examined and the fast response was characterized using voltage clamp techniques. Some patch clamp experiments were also used for the slow response. The slow response was shown to depend on a G protein, which was sensitive to inhibition by pertussis toxin, indicating that it was mediated by a Gi or Go protein. Second messengers such as cyclic AMP, cyclic GMP, IP3, arachidonic acid and Ca2+ along with the activation of protein kinase C were all found not to be directly involved in producing the FMRFamide response. These negative results with the second messengers gave rise to the view that the FMRFamide receptors and K+ ion channels may be linked directly through the activation of G proteins. 5-HT, probably acting through raised cyclic AMP levels, reduced the amplitude of the FMRFamide response which suggests that the channel opened by FMRFamide may be an "S" K+ type channel. Activation of protein kinase C by phorbol ester also reduced the FMRFamide response. A role for protein phosphorylation was indicated by the use of okadaic acid which inhibits protein phosphatases 1 and 2A. Its application reduced the amplitude of the FMRFamide response which suggested that increased protein phosphorylation levels lead to smaller responses. Thus, it seemed possible that protein phosphorylation levels controlled by cyclic AMP, protein kinase C activation and protein phosphatases 1 and 2A might modulate the activity of the receptor/ G protein/ ion channel complex. Alternatively, FMRFamide may operate through the activation of protein phosphatase(s) which reduce protein phosphorylation levels. Patch clamp studies in cell attached mode on the Cl neurone failed to reveal any channel openings induced by FMRFamide. This result also tends to rule out the direct involvement of a second messenger. The fast depolarizing FMRFamide response of the C2 neurone, which is due to the opening of a ligand gated channel, was found to be carried by Na+ and not Ca2+. Amiloride produced a reversible block of the current. Tetrodotoxin and lignocaine had no effect on the FMRFamide response while raised cyclic AMP levels potentiated the response. In the presence of okadaic acid and increased levels of cyclic AMP, the FMRFamide response is potentiated. This potentiation was not maintained in the presence of okadaic acid alone. The raised protein phosphorylation levels therefore did not cause potentiation, which suggested that cyclic AMP may have a direct effect on the receptor/channel complex.

No description available.

No description available.

No description available.

Cette thèse porte sur l’étude de paramètres acoustiques dans parole fluente chez des locuteurs bègues (SB) et des non-bègues (SNB), tunisiens.Les paramètres acoustiques comparés entre SB et SNB incluent le temps d’établissement du voisement (ou V.O.T), la fréquence du fondamental (F0), des mesures du Jitter et du Shimmer, l’étendue et la direction de la transition du second formant (F2), et également les trois premiers formants (F1, F2 et F3) des trois voyelles /a, i, u/. Les résultats sont en accord avec les études antérieures en ce qui concerne le V.O.T, qui serait aussi plus long chez les bègues américains et français. Concernant les valeurs du F0, des différences significatives entre les deux groupes sont obtenues pour /u/. Les mesures du Jitter et du Shimmer ne montrent pas de différences significatives, contrairement aux résultats recueillis chez les bègues américains où la signification est obtenue pour les mesures du Shimmer. Enfin,en ce qui concerne l’étude des variations formantiques, il y a des tendances sans atteindre la signification pour F1, F2 et F3. Les mesures de F2 sont moins élevées chez les bègues avec quelques résultats significatifs obtenus pour les séquences du type C-u. Le triangle vocalique des trois voyelles /a i u/ chez les enfants bègues tunisiens n’est totalement centralisé contrairement aux triangles obtenus chez les locuteurs bègues français et américains, selon la littérature. / This thesis concerns the comparison of acoustic parameters in fluent speech in Tunisian stutterers’ speakers (SB) and non-stutterers (SNB), Tunisians.The acoustic parameters which are compared between SB and SNB include the Voice Onset Time (VOT), the fundamental frequency (F0), the measurements of jitter and shimmer, the scope and direction of the transition of the second formant (F2), and the first three formants (F1, F2 and F3) of the three vowels /a, i, u/. The results are consistent with previous studies regarding the V.O.T, which has been found also be longer for American and French stutterers. Concerning F0values, significant differences between the two groups are obtained for /u/. Measurements of jitter and shimmer show no significant differences, contrary to the results found from American concerning the shimmer. Finally, as regards the study of formant variations, there are tendencies without reaching significance for F1, F2 and F3. F2 values are lower in stutterers with significant results obtained for sequences of C-u. The vowel triangle of the three vowels /a, u, i/ in Tunisian children who stutter, is not centralized, unlike triangles obtained for French and American stuttering speakers, according to the literature.

Ce travail porte sur la synthèse et la caractérisation de fluorures divisés obtenus par voiesolvothermale assistée par chauffage micro-ondes pour la réduction des impuretés dans lecycle du combustible nucléaire. / This work deals with the synthesis and characterization of divided fluorides obtained bysolvothermal process assisted by microwave heating to reduce impurities in the nuclear fuelcycle.

Hair growth disorders cause significant psychological distress, but are poorly controlled. Since prostaglandin F₂α (PGF₂α) and prostamide F₂α analogue glaucoma treatments cause eyelash growth as side-effects, they may be useful for alopecia. How they function is unknown; possibilities include direct action on hair follicles or stimulating follicular blood flow. It is important to clarify whether scalp follicles can also respond as human follicle response to androgens differ with body site. Therefore, human scalp follicles were grown in vitro in organ culture with PGF₂α, latanoprost, a PGF₂α analogue, and bimatoprost, a prostamide F₂α analogue, with, or without, appropriate antagonists, and the presence of PGF₂α (FP) and prostamide F₂α receptors were investigated using molecular biological and immunohiostochemical methods. Each treatment significantly stimulated follicle growth rate, the percentage of growing follicles, and the amount of hair produced in a dose-responsive manner (10nM-1μM); the receptor antagonists blocked these effects. Immunohistochemistry of frozen scalp sections demonstrated FP protein only in dermal papillae and connective tissue sheaths. RT-PCR identified FP and various prostamide F₂α receptors in anagen follicles and isolated dermal papillae and bulbar connective tissue sheath, but not in bulb matrix or other epithelial tissues. Therefore, isolated human scalp hair follicles can respond biologically to PGF₂α and related pharmaceuticals in organ culture via follicular receptors and express the genes and protein for FP and prostamide F₂α receptors. PGF₂α-related drugs appear to act directly on follicles via receptors in the regulatory dermal papilla. They offer an exciting, novel approach for treating alopecia and merit clinical investigation.

Human anaphylatoxin C3a increases glycogenolysis in perfused rat liver. This action is inhibited by prostanoid synthesis inhibitors and prostanoid antagonists. Because prostanoids but not anaphylatoxin C3a can increase glycogenolysis in hepatocytes, it has been proposed that prostanoid formation in nonparenchymal cells represents an important step in the C3a-dependent increase in hepatic glycogenolysis. This study shows that (a) human anaphylatoxin C3a (0.1 to 10 mug/ml) dose-dependently increased prostaglandin D2, thromboxane B, and prostaglandin F2alpha formation in rat liver macrophages (Kupffer cells); (b) the C3a-mediated increase in prostanoid formation was maximal after 2 min and showed tachyphylaxis; and (c) the C3a-elicited prostanoid formation could be inhibited specifically by preincubation of C3a with carboxypeptidase B to remove the essential C-terminal arginine or by preincubation of C3a with Fab fragments of a neutralizing monoclonal antibody. These data support the hypothesis that the C3a-dependent activation of hepatic glycogenolysis is mediated by way of a C3a-induced prostanoid production in Kupffer cells.

Volunteer canola (<i>Brassica napus</i> L.) has become an abundant weed in western Canadian cropping systems. Modern canola cultivars are strong competitors and produce large seed yields, however seed shattering during harvest creates large volunteer seedbanks. The segregation of hybrid trait and changes in variability of traits may allow successive generations of volunteer <i>B. napus</i> weeds to display different levels of fitness and other traits. Three cultivars: 2 hybrid, and 1 open-pollinated at three consecutive generations: G1, the initial crop; G2, first generation of volunteers; and G3 the second generation of volunteers, were used to evaluate the competitive ability, fitness and population dynamics of volunteer canola when grown as a weed in wheat (<i>Triticum aestivum</i> L.). Traits including seed, biomass, and pod production, plant height, seed weight, dormancy, and competitive ability were measured. In all traits but height and seed weight, hybrid breakdown occurred, as the hybrid G1displayed greater mean values than the G2 generation. Hybrids commonly showed the highest mean values of various traits in the G1, lowest mean values in the G2. Hybrid G3 populations produced mean values not different from the G1 or G2 generations for many traits. The open-pollinated cultivar displayed mean values for all traits which did not vary across generations. Generational differences in <i>B. napus</i> seedlings resulted in differences in wheat yield losses. <i>B. napus</i> densities at maturity provided a more robust model of wheat yield loss, as there were differences in wheat yield losses due to the interaction of generation and cultivar of <i>B. napus</i>. Commercial seed generations were the most competitive and fit plants, while volunteer generations were less competitive, and not as fit.

Volunteer canola (<i>Brassica napus</i> L.) has become an abundant weed in western Canadian cropping systems. Modern canola cultivars are strong competitors and produce large seed yields, however seed shattering during harvest creates large volunteer seedbanks. The segregation of hybrid trait and changes in variability of traits may allow successive generations of volunteer <i>B. napus</i> weeds to display different levels of fitness and other traits. Three cultivars: 2 hybrid, and 1 open-pollinated at three consecutive generations: G1, the initial crop; G2, first generation of volunteers; and G3 the second generation of volunteers, were used to evaluate the competitive ability, fitness and population dynamics of volunteer canola when grown as a weed in wheat (<i>Triticum aestivum</i> L.). Traits including seed, biomass, and pod production, plant height, seed weight, dormancy, and competitive ability were measured. In all traits but height and seed weight, hybrid breakdown occurred, as the hybrid G1displayed greater mean values than the G2 generation. Hybrids commonly showed the highest mean values of various traits in the G1, lowest mean values in the G2. Hybrid G3 populations produced mean values not different from the G1 or G2 generations for many traits. The open-pollinated cultivar displayed mean values for all traits which did not vary across generations. Generational differences in <i>B. napus</i> seedlings resulted in differences in wheat yield losses. <i>B. napus</i> densities at maturity provided a more robust model of wheat yield loss, as there were differences in wheat yield losses due to the interaction of generation and cultivar of <i>B. napus</i>. Commercial seed generations were the most competitive and fit plants, while volunteer generations were less competitive, and not as fit.