The aim of my work was to monitor and valorize of postnatal dynamics of thyroid hormones, thyroxine (TT4), triiodothyronine (TT3) and its free fractions (FT3 and FT4), in lambs up to 60 days of age. During the experiment 26 lambs were devided into two groups according to sex and were supplemented by iodine in concentration 0,7 ? 5 mg. Standard directed day ration for sheep is average 0,3 mg of iodine in 1 kilogram of dry mass (DM). One of the groups was also supplemented by selenium in concentration 0,2 ? 0,4 mg in 1 kilogram of DM.

Em nosso laboratório foi demonstrado que ratos submetidos à restrição crônica de sal na dieta apresentaram maior peso corpóreo (PC), menor sensibilidade à insulina e alterações pressóricas em comparação com ratos submetidos à sobrecarga crônica de sal na dieta. No presente estudo, o objetivo foi avaliar alguns mecanismos de obesidade e alterações hormonais associados à dieta hipossódica. Foram utilizados ratos Wistar machos submetidos à dieta hipo (HO: 0,15% NaCl), normo (NO: 1,27% NaCl) ou hipersódica (HR: 7,94% NaCl) desde o desmame até 12 semanas de idade. Nestes animais foram realizadas medidas de pressão arterial (PA), freqüência cardíaca (FC), consumo de ração, PC, perfil dos hormônios [leptina (LEP), GH, insulina (INSh - anticorpo anti-insulina humana), T3, T4 e TSH] e decaimento da 125I-insulina (DEC-INS). O consumo de ração foi avaliado durante sete dias consecutivos com um (1G) ou quatro (4G) ratos por gaiola de plástico e com um rato por gaiola metabólica (1GM). O PC também foi medido neste período. Glicemia (GLI) e insulinemia (INSr - anticorpo anti-insulina de rato) basais foram quantificadas antes da realização do estudo do DEC-INS. Para avaliar o DEC-INS, foi injetado 1mCi de 125I-insulina humana pelo cateter implantado na veia jugular, após 6 a 8 horas de jejum fisiológico. As amostras de sangue foram coletadas pelo cateter implantado na carótida a cada 30 segundos durante 2 minutos e depois a cada 1 minuto até 10 minutos de experimento. Os resultados obtidos demonstraram que ratos submetidos à dieta HR apresentaram maior PA em comparação a ratos em dieta NO e HO. Os ratos submetidos à dieta HO apresentaram menor FC cardíaca em relação ao grupo NO. A avaliação de ingestão alimentar revelou que ratos em dieta HR consumiram maiores quantidades de ração (1G e 4G) em comparação com ratos em dieta NO e HO. O grupo HO apresentou maior PC em comparação com os grupos de ratos NO e HR. Os ratos em dieta HR ou HO apresentaram níveis diminuídos de LEP em comparação com ratos submetidos à dieta NO. Os ratos que receberam dieta HO apresentaram níveis elevados de INSr em comparação com ratos em dieta HR e NO. Os ratos em dieta HR apresentaram níveis elevados de T4 total e níveis reduzidos de TSH em comparação com animais em dieta NO e HO. INSr e GLI basais foram maiores nos ratos em dieta HO do que nos ratos que receberam dieta HR e NO. O DEC-INS (decaimento exponencial) foi mais rápido no grupo HR demonstrado por meio de menor meia-vida da 125I-insulina. Os resultados sugerem que maior PC nos ratos sob restrição salina crônica é devido a maior eficiência metabólica (maior PC e menor consumo de dieta) que pode estar relacionada com alterações hormonais e com a dieta HO. Palavras-chave: Pressão arterial, sal, sódio, ingestão alimentar e perfil hormonal. / Previous studies from our laboratory have shown that chronic salt restriction decreases blood pressure, increases insulin resistance, and body weight (BW) in Wistar rats. The aim of this study was to evaluate some mechanisms of obesity and hormonal alterations associated with chronic salt restriction. Male Wistar rats were fed a low (LSD: 0,15% NaCl), normal (NSD: 1,27% NaCl), or high salt diet (HSD: 7,94% NaCl) from weaning. At the 12th week of age, tail-cuff blood pressure (TCBP), intra arterial blood pressure (BP), heart rate ((HR), food intake, BW, hormonal levels [leptin (LEP), growth hormone (GH), insulin (INSh - antibody anti-human insulin), T3, T4 and TSH] and 125I insulin decay study (DECAY-INS) were measured. To evaluate the food intake and body weight, each dietary group was divided in 3 subgroups, according to housing conditions: one (1C) or four (4C) rats per cage and one rat per metabolic cage (1MC) for daily food consumption and BW determinations during 7 days. Fasting plasma glucose (GLU) and insulin (INSr - antibody anti-rat insulin) were measured before the DECAY-INS. To evaluate the DECAY-INS, 1mCi human 125I-insulin was injected through the jugular catheter after 6-8 hours of food restriction. Blood samples were withdrawn through the carotid catheter every 30 sec during 2min, and in sequence, every 1 min for additional 10 minutes. 125Iinsulin was determined by RIA for human insulin. Rats on HSD had higher intra arterial BP and TCBP compared to rats on NSD and LSD. Heart rate was lower on LSD than on NSD. In all housing conditions, BW was higher on LSD than on NSD and HSD. Food intake was higher on HSD (1C and 4C) than on NSD and LSD. Plasma GH and LEP were higher on NSD than on the 68 other two groups. Plasma INSh was higher in LSD compared to HSD and NSD rats. Plasma total T4 was higher on HSD than on the NSD and LSD, TSH was lower on HSD than on NSD and HSD, and T3 was not different among all groups. Fasting GLU and INSr were higher on LSD compared to HSD and NSD rats. The exponential insulin decay was faster on HSD demonstrated by a lower 125I-INS half-life. These results suggest that obesity in rats on chronic LSD is due to a higher metabolic efficiency (higher body weight and lower diet consumption), that may be related to the hormonal consequences of LSD. Key Words: blood pressure, salt, sodium, food intake and hormonal profile.

Les couches de conversion actuellement utilisées dans l'industrie aéronautique, pour protéger le métal de la corrosion et favoriser l'adhérence de la peinture, contiennent du chrome hexavalent, composé toxique et cancérigène dont l'utilisation va prochainement être interdite par la réglementation européenne REACh. L'une des pistes envisagée pour remplacer ces couches chromatées est l'utilisation de couches de conversion TCP (Trivalent Chromium Protection). Ces travaux portent sur l'étude des couches de TCP et s'attachent à caractériser chaque étape du traitement de surface industriel, incluant les étapes de prétraitement et de post-traitement. Des techniques d'analyse de surface (XPS, ToF-SIMS, AFM, MEB et PM-IRRAS) ont été utilisées pour analyser la composition chimique et la morphologie de la surface après chaque étape du traitement. Cette étude a été réalisée sur un alliage d'aluminium AA 2024-T3, très utilisé en aéronautique pour ses propriétés mécanique, mais présentant une faible résistance à la corrosion. Les résultats obtenus ont notamment mis en évidence que la couche de TCP se forme sur toute la surface de l'alliage (composés intermétalliques et cavités), et ont permis de comprendre comment le post-traitement permet d'améliorer la résistance à la corrosion de la couche de TCP. Ces travaux s'intéressent également à des couches de conversion sans chrome, à base de zirconium, étudiées ici pour servir de point de départ au développement d'une conversion sans chrome qui respecterait les exigences de résistance à la corrosion. / Conversion coatings are used in aerospace industry to protect the metal from corrosion and to promote paint adhesion. Currently, chromate conversion coatings are used, but chromate is toxic and carcinogenic and its use will be forbidden by the European REACh regulation. TCP (Trivalent Chromium Protection) conversion coatings, are considered as a promising alternative to replace chromate conversion coating. This work focuses on the characterisation of the TCP layer and considers each step of the industrial surface treatment, including pre-treatment and post-treatment steps. Surface analytical techniques (XPS, ToF-SIMS, AFM, SEM and PM-IRRAS) were used to analyse the chemical composition and morphology of the surface after each step in the process. This work was done on an aluminium alloy AA 2024-T3, commonly used in the aerospace industry for its good mechanical properties, but poorly resistant to corrosion. The results obtained demonstrate, among other things, that the TCP layer totally covers the surface (intermetallic compounds and cavities) and enable to understand how the post-treatment can improve the corrosion resistance of the TCP coating. This work also focuses on conversion coating based on zirconium, which are studied here to be used as a starting point to develop a new conversion coating without chromium, meeting the corrosion resistance requirement.

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Mon projet de thèse s'inscrit dans un vaste projet de caractérisation de protéines nouvellement identifiées dont l'expression est sélective à certaines régions du cerveau. Cette expression sélective pouvant être liée aux phénomènes de dégénérescence neuronale qui caractérisent les maladies neurodégénératives, ces protéines constituent donc des biomarqueurs potentiels. Une étude structurale et physico-chimique a été effectuée sur une dizaine de protéines, dont la protéine CRYM murine (mCRYM) qui fait parti de la famille des Cytosolic- 3,3',5-triiodo-L-thyronine(T3)-Binding Protein car elle régule la concentration en hormone thyroïdienne T3 libre dans la cellule. mCRYM appartient également à la famille des µ-crystallines et à la superfamille des µ-crystallines/Ornithines Cyclodésaminases. Les protéines présentant des homologies pour ces trois familles sont la plupart différentes par leur fonction (enzymatique ou structurale), leur localisation tissulaire et leurs caractéristiques physico-chimiques. Cette diversité est due au recrutement de gènes de la superfamille des crystallines pour diverses fonctions métaboliques tout en conservant le taxon spécifique des crystallines. Je suis parvenue à résoudre sa structure cristallographique complexée au NADP(H) et à l'hormone thyroïdienne T3 à une résolution de 1,75 Å. La protéine mCRYM est un exemple intéressant d'évolution par son appartenance à différentes familles de protéines et, à ce jour, aucune activité enzymatique n'a été identifiée. Sa caractérisation structurale et thermodynamique a donc permis de mettre en évidence les différences et les similitudes avec ses homologues enzymatiques et d'émettre des hypothèses quant à son évolution moléculaire. Ces résultats soulèvent de nouvelles questions concernant son rôle physiologique : mCRYM est-elle une enzyme ou une protéine structurale ? Comment intervient le couple redox NADPH/NADP+ pour réguler l'action génomique et/ou non génomique de l'hormone T3 ? L'hormone T3 est-il le seul ligand physiologique de CRYM dans le cerveau ?

L'objectif de cette thèse était d'identifier certains processus liés au fonctionnement des nourriceries de la<br />sole Solea solea (L.) dans les pertuis Charentais, bassin ostréicole de 1er rang européen et nourriceries majeures<br />pour la sole du golfe de Gascogne. Les juvéniles de la sole dépendent d'habitats côtiers et estuariens, ce qui<br />implique (i) une capacité d'adaptation à la variabilité environnementale de ces milieux et (ii), l'accès à l'intégralité<br />d'un habitat essentiel au cycle biologique de l'espèce. La nourricerie réalisée rend compte des ajustements que le<br />poisson doit opérer entre les contraintes liées à l'habitat et sa capacité à gérer ces contraintes, à travers la<br />sélection des aires de nourrissage, de repos et de refuge. Couplant travaux de terrains et expériences en<br />mésocosme, des méthodes basées sur des estimateurs intégratifs ont été retenues, taux de croissance, indice de<br />condition de Fulton et statut endocrine de ces poissons. Ces résultats ont été confrontés à une approche<br />comportementale visant à déterminer comment les soles utilisent l'espace (pistage par télémétrie acoustique) et<br />accèdent à la nourriture (régime alimentaire et estimation de la ration en équivalent carbone) dans un habitat sous<br />influence conchylicole.<br />La croissance des juvéniles du pertuis Breton, sub-maximale durant la période de croissance rapide, tend<br />vers un plateau autour de l'équinoxe d'automne. Une expérience en mésocosme confirme que la température in<br />situ ne peut entraîner ce ralentissement de la croissance. Or en même temps, ces juvéniles présentent une<br />condition médiocre, les niveaux d'hormones thyroïdiennes circulantes les plus faibles et l'activité alimentaire la plus<br />basse de l'année. Cet état suggère des contraintes propres à la mer des Pertuis, système de baies semi-fermées<br />sous influence modérée de panaches estuariens. Il semble qu'un environnement marin moins favorable en fin d'été<br />et/ou des effets en cascade sur le réseau trophique ne permettent pas à l'intégralité de la classe d'âge 0 d'y grandir<br />en fonction des potentialités de l'espèce. Dans le contexte climatique actuel néanmoins, une partie d'entre eux est<br />capable d'hiverner dans ces nourriceries où ils recouvrent des niveaux hormonaux élevés et restaurent leur activité<br />alimentaire. Les contraintes environnementales des pertuis Charentais, si elles sont d'ordre à moduler la<br />croissance des soles, ne semblent pas altérer leur comportement. Nous avons pu montrer par une expérience en<br />mésoscosme que ni l'effet des structures d'élevage, ni celui des modifications d'habitat liées à la biodéposition ne<br />restreignent l'accès aux zones placées sous emprises ostréicoles. Vérifier ces résultats en mer sera nécessaire<br />avant de conclure que les juvéniles accèdent à l'intégralité des nourriceries dans les pertuis Charentais. Toutefois,<br />deux cycles d'alimentation de 30 h dans le pertuis d'Antioche démontrent la capacité de très jeunes soles à ajuster<br />leurs rythmes d'activité et l'intensité de la prise alimentaire selon, vraisemblablement, le contexte hydrodynamique,<br />qu'il soit imposé par le cycle des marées de quinzaine ou par le vent. Cela a également permis une première<br />estimation de la ration journalière des jeunes soles en carbone organique, ce qui permettra de compléter les<br />modèles de réseau trophique actuellement développés. Enfin, l'infestation importante des soles des pertuis par les<br />métacercaires d'un Bucephalidae, enkystées dans différents organes sensibles, révèle des interactions biotiques<br />inattendues. Les cercaires de ce parasite étant propagées par les élevages de moules, cette parasitose donne un<br />nouvel éclairage aux interactions existant entre la fonction de nourricerie des habitats côtiers et la conchyliculture.

Fibroblast growth factor-23 (FGF23) is a novel, bone-produced hormone that regulates renal phosphate (Pi) reabsorption and calcitriol metabolism. Disorders of mineral and bone metabolism, such as autosomal dominant hypophosphatemic rickets (ADHR) and hyperostosis-hyperphosphatemia syndrome (HHS), witness the importance of well-balanced serum levels of FGF23. Patients with chronic kidney disease (CKD) are highly morbid due to Pi retention/hyperphosphatemia and calcitriol deficiency, which lead to elevated serum levels of parathyroid hormone (PTH) and secondary hyperparathyroidism (sHPT). As a response to hyperphosphatemia, CKD patients have also remarkably high serum FGF23 levels, which are associated with cardiovascular risk factors and increased mortality in CKD. The overall aim of this dissertation was to discern a possible role of FGF23 in parathyroid biology. Our in vitro experiments on isolated bovine parathyroid cells demonstrate that FGF23 directly and dose-dependently suppresses the PTH production and secretion, while increasing the expression of the 25-hydroxyvitamin D3-activating enzyme 1α-hydroxylase. We investigated possible expressional changes in the FGF23 receptor co-factor Klotho in hyperparathyroid disorders and found that Klotho expression is decreased or absent and inversely correlated to serum calcium (Ca) in adenomas of primary HPT (pHPT). In the hyperplastic parathyroid glands of sHPT, Klotho expression declines in parallel with the kidney function and correlates with the glomerular filtration rate. Moreover, Klotho expression is suppressed by Ca and FGF23, increased by calcitriol, but unaffected by Pi and PTH in vitro. Finally, we identified a novel missense mutation in the gene encoding GALNT3, which is normally involved in the post-translational glycosylation of FGF23, as the cause of aberrant FGF23 processing in a patient with HHS. In summary, we provide evidence for a novel bone/parathyroid axis in which FGF23 functions as a direct, negative regulator of the PTH production. High extracellular Ca is a major determinant of the Klotho expression in pHPT, whereas the Klotho levels in sHPT may be attributed to a combination of the high FGF23 and Ca, and low calcitriol levels associated with CKD. Hence, the decreased Klotho expression in sHPT could explain the concomitantly high FGF23 and PTH levels, as well as the failure of FGF23 to prevent or mitigate the development of sHPT in CKD.

In freshwater, there is more opportunity for silver (Ag) to interact with organic ligands than in seawater. Triclosan is an antibiotic agent which resembles thyroid hormone T3 and is finding its way into aquatic systems. Preliminary toxicology studies for the frogSCOPE program suggest that triclosan and nanosilver (nanoAg), also used as an antibiotic agent, may be chemically interacting, as they seem to synergistically increase the endocrine-disrupting abilities already observed independently in each chemical. Ag speciation methods can be used to determine if triclosan or thyroid hormone T3 are interacting with Ag ion (Ag+), which gets released over time by nanoAg. To fully utilize Ag speciation methods, however, total Ag in the sample must also be independently analyzed. Here we investigated a new total Ag analysis using cadmium sulfide quantum dots (CdS QDs) as fluorescence probes in solution. This method promises results in a fraction of the time of the established competitive ligand equilibration-solvent extraction (CLE-SE) technique utilizing PDC- and DDC- to bind Ag and bring it out of solution. Following this investigation were a series of experiments using CLE-SE for total Ag and Ag speciation in well water used to house bullfrog tadpoles in frogSCOPE Ag exposure studies. CLE-SE for Ag speciation was also applied to well water samples containing the two levels of nanoAg or Ag+ used in frogSCOPE Ag exposures, and used in ligand competition experiments to examine the potential of triclosan or T3 to act as strong Ag-binding ligands, as compared to glutathione and EDTA, two known Ag-binding ligands. The results of the latter experiments could be used to determine if either of these could be forming complexes with Ag which increase or decrease their delivery to amphibian cells. The fluorometric method using CdS QDs showed no ideal analytical response to nanomolar Ag+, even when commercial QDs were modified and used, so it could not be applied to our samples. Using CLE-SE for total Ag, the well water used as a base for toxicity studies in frogSCOPE contained Ag below the method detection limit of 5 pM. Using the speciation variation of the CLE-SE method, no evidence of naturally-occurring ligands which could produce extractable (hydrophobic) or non-extractable (hydrophilic) Ag complexes was found in this well water. EDTA and glutathione responded as model Ag-binding ligands to form non-extractable hydrophilic Ag complexes in fresh water. T3 behaved like these model ligands, while triclosan enhanced the extractability of Ag in the presence of certain concentrations of the added ligand, DDC-. In another set of experiments, coordination of Ag by triclosan or T3 was not detectable within that analytical window. These results suggest that ionic Ag released over time by nanoAg may be binding T3 and preventing it from reaching its receptor, but confirming the interaction of triclosan and Ag+ will require additional experiments using different analytical windows.

No description available.