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Estudo e desenvolvimento de uma nova metodologia de produção de iodo-125 a partir de xenônio-124 pelo método de ativação neutrônica / Study and development of a new methodology for production of iodine-125 from xenon-124 through the method of neutron activationCOSTA, OSVALDO L. da 10 December 2015 (has links)
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-12-10T17:38:32Z
No. of bitstreams: 0 / Made available in DSpace on 2015-12-10T17:38:32Z (GMT). No. of bitstreams: 0 / Neste trabalho foi desenvolvida uma nova metodologia de produção de iodo-125, que resultou na primeira produção deste radionuclídeo no Brasil. Cápsulas de alumínio foram projetadas, fabricadas e avaliadas para que suportassem condições de pressão, temperatura e fluxo de nêutrons no reator nuclear IEA-R1 do IPEN sem a ocorrência de liberação de material radioativo. Foram projetados, desenvolvidos e fabricados sistemas de carregamento, descarregamento e recuperação dos gases para a manipulação do gás xenônio e do iodo. Foi desenvolvido um novo método de lavagem da cápsula, para dissolução do iodo-125 adsorvido nas paredes, por meio de imersão em banho ultrassônico. Foram irradiadas três cápsulas no reator nuclear IEA-R1, por um período de aproximadamente 60 h contínuas, a um fluxo de nêutrons de 5,5 x 1013 n cm-2 s-1. Foi produzido um total de 13,53 GBq (365,73 mCi) de iodo-125, e o único contaminante encontrado foi o radionuclídeo iodo-126. Na análise radioquímica, pelo método de cromatografia em papel ascendente, o iodo-125 em solução de NaOH apresentou percentual de iodeto acima de 98%, superior à exigência da farmacopeia americana para soluções de iodo radioativo que é de 95%. Para a análise radionuclídica foi desenvolvida uma fonte planar, a base de resina epoxídica, para a contagem do iodo-125 em detector de germânio de alta pureza. A correlação entre o iodo-125 e o iodo-126 produzido apresentou valores entre 0,5 e 0,7% após um período de decaimento de 10 d, grau de pureza suficiente para a utilização em técnicas de radioimunoensaio. / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Exploring the iodine(III)-mediated ring contraction: new substrates, novel conditions and asymmetric reactions / Explorando a contração de anel mediada por iodo(III): novos substratos, novas condições e reações assimétricasAnees Ahmad 28 August 2015 (has links)
In the first section this thesis includes the reactivity of various oxygen-containing benzofused cyclic alkenes with HTIB (Hydroxy(tosyloxy)iodobenzene). Instead of getting ring contraction products, 2H-chromene resulted in 4H-chromenes together with trans-addition products. Only cis-addition products were isolated from 4-methyl-2H-chromene. Ring contraction was observed in dihydrobenzoxepines and 2,2-dimethyl-2H-chromenes giving functionalized chromanes and benzofurans, respectively. In the second part, the ring contraction of 1,2-dihydronaphthalenes using HTIB was expanded to substrates bearing oxygen and nitrogen substituents in the aromatic ring. The N-protecting groups Fmoc and Bz are stable under the reaction conditions giving indanes in 64-77% yield. The Ts-protected substrate gave only addition products. Acetoxy and benzoyloxy alkenes afforded indanes in 60-71% yield. A new and efficient method for the oxidative rearrangement (ring contraction and expansion) of alkenes using in situ generated iodine(III) is described in the third section. The protocol uses inexpensive and stable chemicals (PhI, mCPBA and TsOH) furnishing rearrangement products in yields comparable to those obtained using commercially available iodine(III). Additionally, a new route for the one step transformation of 4-methyl-1,2-dihydronaphthalene into 1-methyl-2-tetralone using mCPBA and TsOH was developed. In the last section is presented the reactivity of chiral iodine(III) with 1,2-dihydronaphthalenes. The hypervalent iodine species is generated in situ from chiral aryl iodide, which is prepared in one high yield step from inexpensive starting materials. Protected (Ac, Bz and Fmoc) amine alkenes gave indanes in 60-75% and 58-64% ee. In the same way, oxygenated substrates afforded acetal in 41-61% yield and 54-78% ee. Ring contraction products were obtained in 77-88% yield and 34-40% ee when 1-methyl and aryl substituted alkenes were utilized. / A primeira parte desta tese inclui a reatividade de vários alquenos benzofundidos cíclicos contendo oxigênio com HTIB (Hidróxi(tosilóxi)iodobenzeno). Em vez de obter os produtos de contração de anel, 2H-cromeno resultou em 4H-cromenos, juntamente com produtos trans-adição. Apenas produtos de adição de cis foram isolados a partir de 4-metil-2H-cromeno. Contração do anel foi observada em di-hidrobenzoxepinas e 2,2-dimetil-2H-cromenos dando cromanos funcionalizados e benzofuranos, respectivamente. Na segunda parte, a contração de anel de 1,2-di-hidronaftalenos usando HTIB foi expandida para substratos contendo substituintes de oxigênio e de nitrogênio no anel aromático. Os grupos N-protetores Fmoc e Bz são estáveis sob as condições de reação fornecendo indanos em 64-77% de rendimento. O substrato protegido com Ts deu apenas os produtos de adição. Acetóxi e benzoilóxi alquenos geraram indanos em 60-71% de rendimento. Um método novo e eficiente para o rearranjo oxidativo (contração e expansão do anel) de alquenos utilizando iodo(III) gerado in situ é descrito na terceira parte. O protocolo utiliza reagentes baratos e estáveis (PhI, mCPBA e TsOH) fornecendo produtos de rearranjo com rendimentos comparáveis aos obtidos utilizando iodo(III) disponível comercialmente. Além disso, um método para a transformação em uma etapa de 4-metil-1,2-di-hidronaftaleno em 1-metil-2-tetralona utilizando mCPBA e TsOH foi desenvolvido. Na última parte é apresentada a reatividade de iodo(III) quiral com 1,2-di-hidronaftalenos. A espécie de iodo hipervalente é gerada in situ a partir de iodeto de arila quiral, o qual é preparado em uma etapa em rendimento elevado a partir de materiais de partida baratos. Amino alquenos protegidos (Ac, Bz e Fmoc) deram indanos em 60-75% de rendimento e 58-64% ee. Da mesma forma, os substratos oxigenados proporcionram acetais em 41-61% de rendimento e 54-78% de ee. Produtos de contração de anel foram obtidos em 77-88% de rendimento e 34-40% de ee quando alquenos 1-metil e aril substituídos foram utilizados.
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An Animal Study of Low-cost Texas Diets in Supporting Reproduction, Lactation, and Iodine NeedsHicks, Gladys 08 1900 (has links)
A study of low-cost Texas diets to support reproduction, lactation, and iodine needs in animals.
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Predicting market pig weights and fat iodine value and effect of zinc on growth performance and immune function of finishing pigsPaulk, Chad Bennett January 1900 (has links)
Doctor of Philosophy / Department of Animal Science / Jim L. Nelssen and Michael D. Tokach / The optimum sampling method swine producers should use to estimate the mean and SD of pig BW within a barn was determined based upon both the time required to conduct and the precision and accuracy of each sampling method. Weighing 5 pigs from 15 pens was determined to be the optimal sampling method. This should require approximately 55 min to complete. Weighing 5 pigs from 15 pens had a CI range of 7.2 to 8.0 kg for estimating the mean BW and 5.6 kg for estimating SD. Next, a meta-analysis was conducted using data from existing literature to generate equations to predict finishing pig back, belly, and jowl fat iodine value. While numerous factors were evaluated, dietary essential fatty acids, dietary net energy content, and backfat thickness had the greatest influence on predicting iodine value of the 3 distinct fat depots. Lastly, 6 experiments were conducted to determine the effects of added Zn on growth performance, pork quality, plasma Zn, and ileal mucosal inflammation mRNA expression of finishing pigs fed diets containing ractopamine-HCl (RAC; Elanco Animal Health, Greenfield, IN). Additional Zn increased plasma Zn and reduced relative expression of IL-1β, but did not improve growth performance of pigs fed diets containing RAC in 5 of the experiments. However, in 1 of the experiments, adding Zn to diets containing RAC resulted in a trend for improved growth performance of pigs. Supplementing the RAC diets with dietary Zn decreased the percentage of type IIA fibers and tended to increase the percentage of type IIX fibers compared to pigs fed the RAC diet without added Zn. Ractopamine-HCl produced chops that were lighter and less red, but possessed reduced metmyoglobin reducing ability at the end of the display period. However, adding Zn to RAC diets increased metmyoglobin reducing ability levels at the end of the display period.
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Effects of pelleting and dietary fat and fiber levels on pig growth and fat qualityNemechek, Jeremiah Eugene January 1900 (has links)
Doctor of Philosophy / Department of Animal Sciences and Industry / Mike Tokach / In 11 experiments, 7,325 pigs were used to determine the effects of: 1) diet type and form on finishing pig growth performance and carcass fat iodine value (IV); 2) pellet quality and feeder adjustment on pig growth performance; 3) corn particle size and diet form on finishing pig growth performance and carcass characteristics; and 4) dietary acidification, diet complexity, and feed-grade antibiotics on nursery pig growth performance. Feeding diets with wheat middlings and dried distillers grains with solubles all the way until marketing decreased G:F and carcass yield, and worsened carcass fat IV. Withdrawing these ingredients 17 d prior to market restored carcass yield, but resulted in small improvements in IV. Pelleting diets improved growth performance; however, a novel finding is that pelleting diets fed to finishing pigs increased belly fat IV. Feeding nursery pigs from a wide feeder gap may improve ADG and ADFI, with no negative effects on G:F. For finishing pigs, reducing feeder gap reduced feed disappearance and improved G:F. In all experiments, feeding pelleted diets improved G:F, but the greatest improvements occurred when the percentage of fines was minimized. Grinding corn finer than 650 microns decreased ADFI and improved G:F for finishing pigs fed meal diets, but not for pigs fed pelleted diets. Pelleting diets improved ADG and G:F, but the greatest magnitude of G:F improvement to pellets occurred when pigs were fed diets containing the largest particle size corn. Thus, grinding corn finer than 650 microns improved feed efficiency for finishing pigs fed meal diets, but provided no additional benefit for pigs fed pelleted diets. When dietary supplementation of benzoic acid was evaluated, added benzoic acid in nursery pig diets did not influence growth performance in university conditions, whereas feeding complex diets or antimicrobials improved growth. In the commercial setting, acidifiers improved growth in one
experiment but not the other. The varying response to acidifiers is likely influenced by health status, age, or starting weight of pigs.
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Response to radioiodine in male hyperthyroid patients at Tygerberg HospitalOnimode, Yetunde Ajoke 03 1900 (has links)
Thesis (MSc (Medical Imaging and Clinical Oncology. Nuclear Medicine))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Radioiodine therapy is reputed to yield poorer results in male patients than in females. We
retrospectively reviewed the records of 308 patients treated with radioiodine-131 (RAI) for Graves’
disease (n=266, 86.4%), toxic multinodular goitres (n=35, 11.4%) and toxic solitary nodules (n=7,
2.3%).
The mean age of the men was 44 ±13.6 years (range 14-77 years). Patients with GD were
predominantly in the younger age groups, while those with toxic nodular goitres were in the older
range. Two hundred and fifty-nine patients (84.1%) were treated with a single dose of RAI, while
49 (15.9%) required further doses. A second dose had to be administered to 38 patients, while 8
received 3 doses, 2 got 4 doses and 1 patient had 5 doses in all (these included a first dose received
prior to referral to our Thyroid Clinic). Cure was determined as euthyroidism or hypothyroidism at
the 3-month follow-up visit.
The average pre-treatment T4 value was 68.9 ± 31.8 pmol/L (range 5.7 – 155 pmol/L); while the
mean Tc-99m pertechnetate uptake value was 15.8 ± 10.9% (range 0.88 - 62.9).
Patients with GD presented with more severe hyperthyroidism than the other patients; mean free T4
of 71.9 ± 31.1 pmol/L compared to 51.4 ± 29.9 pmol/L for the TMG group of patients, and 39.6 ±
26.8 pmol/L for the TSN group (ANOVA p<0.0001, confirmed by the Kruskal-Wallis test). Patients
with TMG and TSN were treated with higher doses than patients with GD; mean first doses of
349.3 ± 88.5 MBq and 428.1 ± 28.6 MBq respectively, compared to a mean dose of 325.1 ± 69.3
MBq for patients with GD. Treatment with multiple doses of RAI correlated with higher values of
T4 and T3 at presentation (p<0.0001). However, none of the baseline variables of age, T4 and T3,
and first dose of RAI was significant predictors of free T4 outcome at 3 months. A consistently
higher dose was administered to the male patients, compared to female patients of similar age,
diagnosis and level of thyrotoxicosis (Tc-99m pertechnetate uptake). Despite this, male patients had
similar outcomes as the female patients 3 months after therapy.
Our findings lend weight to the theory that male patients are more difficult to treat than their female
counterparts, seeing that the former had similar outcomes despite the significantly higher doses of
RAI administered to the males. / AFRIKAANSE OPSOMMING: Radiojodium terapie lewer na bewering swakker resultate in mans as in vroulike pasiënte. Die
inligting van 308 pasiënte met Grave se siekte (n=266, 86.4%), toksiese multinodulêre tiroïed
(n=35, 11.4%) en enkel toksiese nodules (n=7, 2.3%) wat met radiojodium (I-131) behandel is, is
retrospektief nagegaan.
Die gemiddelde ouderdom van die mans was 44 ±13.6 jaar (reikwydte 14-77 jaar). Die meeste
pasiënte met Grave se siekte was in die jonger ouderdomsgroep, terwyl dié met toksiese
multinodulêre tiroïed, ouer was. Tweehonderd nege-en-vyftig pasiënte (84.1%) is met ‘n enkel
dosis radiojodium behandel, terwyl 49 (15.9%) meer as een dosis benodig het. ‘n Tweede dosis is
aan 38 pasiënte gegee, terwyl agt 3 dosisse, twee 4 dosisse en 1 pasiënt 5 dosisse in totaal ontvang
het (wat ‘n eerste dosis voor verwysing na die tiroïedkliniek, ingesluit het). Herstel is gedefinieer as
eutiroïdisme of hipotiroidisme tydens die drie maande opvolgbesoek.
Die gemiddelde T4-waarde voor behandeling was 68.9 ± 31.8 pmol/L (reikwydte 5.7–155 pmol/L);
terwyl die gemiddelde Tc-99m pertegnetaatopname 15.8 ± 10.9% (reikwydte 0.88–62.9) was.
Pasiënte met Grave se siekte het met erger hipertiroidisme as die ander pasiënte gepresenteer; met
‘n gemiddelde vry T4 van 71.9 ± 31.1 pmol/L vergeleke met 51.4 ± 29.9 pmol/L vir die toksiese
multinodulêre tiroïedgroep en 39.6 ± 26.8 pmol/L vir die enkel toksiese nodule groep (ANOVA
p<0.0001, bevestig met die Kruskal-Wallistoets). Pasiënte met toksiese multinodulêre tiroïed en
enkel toksiese nodule, is met hoër dosisse as dié met Grave se siekte behandel; met ‘n gemiddelde
eerste dosis van 349.3 ± 88.5 MBq en 428.1 ± 28.6 MBq onderskeidelik, vergeleke met ‘n
gemiddelde dosis van 325.1 ± 69.3 MBq vir pasiënte met Grave se siekte. Behandeling met meer as
een dosis radiojodium het gekorreleer met hoër T4- en T3- waardes by (p<0.0001). Geen van die
basislyn veranderlikes (ouderdom, T4 en T3, en die eerste dosis radiojodium) was egter ‘n
betekenisvolle voorspeller van die vry T4 uitkoms op 3 maande nie. Die dosis wat aan manlike
pasiënte toegedien is, was konstant hoër, vergeleke met die vroulike pasiënte van dieselfde
ouderdom, diagnose en vlak van tirotoksikose. (Tc-99m pertegnetaatopname). Ongeag hiervan, was
die uitkoms by manlike en vroulike pasiënte 3 maande na terapie dieselfde.
Ons bevindinge dra by tot die teorie dat manlike pasiënte moeiliker is om te behandel as hul
vroulike eweknieë, aangesien mans soortgelyke uitkomste gehad het ten spyte van betekenisvol
hoër dosisse radiojodium.
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NMR studies on the mechanism of iodine mediated polymerisationWright, Trevor 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: In reverse iodine transfer polymerisation (RITP), chain transfer agents (CTAs) are
generated in situ from the reaction between 2,2’-azobis(isobutyronitrile) (AIBN) and
molecular iodine. This stage of RITP is the inhibition period, which ends when all
iodine has been consumed. The evolution of CTAs was studied for the
polymerisation reactions of n-butyl acrylate and styrene respectively. RITP of n-butyl
acrylate was performed at 70 °C. In situ 1H nuclear magnetic resonance (NMR)
experiments were carried out to study the evolution of CTAs during the inhibition
period of n-butyl acrylate polymerisation and the structures A-I and A-Mn-I (where A
represents the moiety originating from AIBN, M represents the monomer unit and n is
the mean number degree of polymerisation) were observed. A polymer with the
general structure A-Mm-I is formed. The molecular weight of poly(n-butyl acrylate)
(PnBA) was evaluated with size exclusion chromatography (SEC) and NMR.
Structural analysis of PnBA was done using NMR spectroscopy and matrix-assisted
laser desorption/ionisation time-of-flight (MALDI-ToF) mass spectrometry. Similar
conditions to those used for n-butyl acrylate polymerisation were used for RITP of
styrene. The evolution of CTAs during the inhibition period of styrene polymerisation
was studied using in situ 1H NMR. The inhibition period of styrene polymerised by
RITP was much shorter than expected. This is due the consumption of iodine in the
reaction between styrene and iodine which reversibly forms 1,2-diiodo-ethyl benzene.
The CTAs A-I and A-Mn-I are formed, as well as 1-phenylethyl iodide (1-PEI). The
molecular weight of polystyrene (PS) was determined using SEC and NMR and the
functionality was evaluated using 1H NMR. The structure of PS was confirmed with
1H NMR and MALDI-ToF mass spectrometry. By increasing the temperature of the
reaction, the inhibition period can be shortened. Both polymerisation systems retain
control over molecular weight with an increase in temperature, however, n-butyl
acrylate is limited due to the possible formation of mid-chain radicals. The formation
of an A–Mm–A population (direct combination of the initiator and styrene) in RITP of
styrene results in more initiator being consumed than for n-butyl acrylate, despite
limited conversion of styrene to polymer. / AFRIKAANSE OPSOMMING: In omgekeerde-jodium-oordrag polimerisasie, is die kettingoordragagente
gegenereer in situ van die reaksie tussen 2,2’-azobis(isobutironitriel) (AIBN) en
molekulêre jodium. Hierdie fase van RITP is die inhibisie tydperk wat eindig wanneer
alle jodium verbruik is. Die evolusie van kettingoordragagente is vir die
polimerisasiereaksies van butielakrilaat en stireen onderskeidelik bestudeer.
Omgekeerde-jodium-oordrag polimerisasie van butielakrilaat was uitgevoer by 70 °C.
In situ 1H kernmagnetieseresonans (KMR) eksperimente is uitgevoer om die evolusie
van die kettingoordragagente te bestudeer tydens die inhibisie van butielakrilaat
polymerisasie en die strukture A-I en A-Mn-I (waar A die gedeelte voorstel wat
afkomstig is van AIBN, M die monomeer-eenheid en n die gemiddelde aantal
polymerisasiegraad verteenwoordig) is ge-identifiseer. 'n Polimeer met die algemene
struktuur A-Mm-I is gevorm. Die molekulêre gewig van poli(butielakrilaat) (PnBA) was
geëvalueer deur grootte-uitsluitings chromatografie en KMR spektroskopie.
Strukturele ontleding van PnBA is gedoen deur die KMR spektroskopie en matriks
ge-assisteerde laser desorpsie/ionisasie tyd-van-vlug massaspektroskopie.
Soortgelyke kondisies as dié wat gebruik word vir butielakrilaat polymerisasie, is
gebruik vir omgekeerde-jodium-oordrag polimerisasie van stireen. Die evolusie van
die ketting oordrag agente gedurende die inhibisie periode van stireen polymerisasie
is deur in situ 1H KMR bestudeer en die inhibisie periode is baie korter as verwag. Dit
is as gevolg van die opname van jodium in die reaksie tussen stireen en jodium wat
omkeerbare stireen-di-jodied tot gevolg hê. Die ketting oordrag agente A-I en A-Mn-I
is gevorm, sowel as 1-feniel-etiel jodied. Die molekulêre massa van polistireen (PS)
is bepaal met behulp van grootte-uitsluitings chromatografie en KMR spektroskopie
en die funksioneering is geëvalueer met behulp van 1H KMR. Die struktuur van PS is
bevestig deur 1H KMR en matriks ge-assisteerde laser desorpsie/ionisasie tyd-vanvlug
massaspektroskopie. Deur die verhoging van die temperatuur van die reaksie,
kan die inhibisie periode verkort word. Beide polimerisasie sisteme behou beheer oor
die molekulêre massa met 'n toename in temperatuur, alhoewel butielakrilaat beperk
word as gevolg van die moontlike vorming van middel kettingradikale. Die vorming
van die A-Mm-A spesie (direkte kombinering van AIBN en stireen) in omgekeerdejodium-
oordrag polimerisasie van stireen veroorsaak dat meer AIBN verbruik word as
butielakrilaat, ten spyte van die beperkte omskakeling van stireen tot polimeer.
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L'hypothyroïdie juvénile endémique en Ubanga, ZaïreVanderpas, Jean 01 January 1994 (has links)
<p align="justify"><i>Note des Bibliothèques : la thèse du Dr Vanderpas a été défendue en 1991 mais il n'est techniquement pas possible d'indiquer cette date dans le logiciel Bictel/e.</i></p>
<p align="justify"><u>Première partie</u> : Fonction thyroïdienne de la naissance à 7 ans chez les enfants d’un essai clinique de supplémentation d’huile iodée versus placebo à la femme enceinte.</p>
<p align="justify">L’endémie goitreuse du Nord-Congo (République démocratique, ex-Zaïre) a fait l’objet d’un programme de santé publique de prévention du goitre et du crétinisme dans le cadre du Centre d’Etudes Médicales de l’Université Libre de Bruxelles pour les actions de coopération de 1974 à 1995. Le partenaire congolais était l’Institut de Recherche Scientifique et le Bureau National des Troubles dus à la Carence Iodée.</p>
<p align="justify">Le présente travail s’inscrit dans ce contexte et analyse plus particulièrement la fonction thyroïdienne chez l’enfant de zéro à sept ans, dans la continuité d’un suivi d’un essai clinique pharmacologique randomisé et contrôlé (RCT, Randomised Clinical Trial) de phase 2 consistant à administrer une huile iodée (Lipiodol®) à des femmes enceintes se présentant à la maternité de Karawa. Cette cohorte de femmes enceintes a été précédemment étudiée par le Professeur Claude-Hector Thilly*.</p>
<p align="justify">Chez les enfants nés de mères non supplémentées en iode, l’histoire fonction thyroïdienne se caractérise comme suit :
<li>Une fonction thyroïdienne relativement stable au ours de la première année de vie par rapport aux valeurs de TSH et de T4 sériques du sang de cordon ; les moyennes de ces marqueurs biologiques sont clairement indicateurs d’un niveau de carence iodée par rapport aux normes d’une population d’enfants belges d’âge comparable (T4 sérique abaissée et TSH sérique élevée) ;</li>
<li>Une aggravation des altérations de la TSH et de la T4 sériques au cours de la deuxième année de vie, aggravation qui se poursuit jusqu’à la quatrième année ;</li>
<li>Un maintien de marqueurs biologiques de TSH et T4 sérique fortement altérés au moins jusqu’à l’âge de 7 ans (étendue d’âge étudiée).</li></p>
<p align="justify">Dans cette région, le manioc est connu pour son rôle goitrogène, au travers de son contenu en glucosides cyanogènes, et il avait été précédemment démontré que le thiocyanate élevé des mères passait librement la barrière placentaire. Au cours de la première année de vie, lorsque les nourrissons sont essentiellement alimentés au sein, le thiocyanate sérique diminue fortement et se rapproche de valeurs observées chez des enfants d’autres régions non exposés au manioc. La dégradation de la fonction thyroïdienne au cours de la deuxième année de vie coïncide avec l’introduction du manioc dans l’alimentation. Pour une valeur de concentration urinaire en iode stable au cours des 7 premières années de vie, la prévalence de goitre et les variations de T4 et TSH sériques suivent celles du thiocyanate sérique. Cela est confirmé au travers d’une analyse multi-variée qui met en évidence l’association entre les valeurs moyennes de TSH et T4 et les concentrations urinaires en iode et en thiocyanate.</p>
<p align="justify">L’administration intra-musculaire d’huile iodée prévient les altérations de la fonction thyroïdienne chez la mère (Thilly 1978), et cette protection s’étend chez l’enfant jusqu’à 24 mois, c’est-à-dire jusqu’à ce que l’allaitement maternel reste le principal apport nutritionnel. Au-delà de 24 mois, des altérations de la fonction thyroïdienne apparaissent chez certains de ces enfants (Elévation de la TSH et abaissement de la T4), et au-delà de 4 ans, la fréquence des altérations de la fonction thyroïdienne est aussi fréquente chez les enfants de mères traitées que chez les enfants de mères non traitées.</p>
<p align="justify">Au vu de la fréquence fort élevée d’altérations de la fonction thyroïdienne entre 4 et 7 ans (2/3 ont une TSH anormalement élevée > 10 mU/L), seuls certains enfants présentent les stigmates d’une hypothyroïdie prolongée depuis le début de l’existence. Il apparaît qu’il y a lieu de distinguer des hypothyroïdies juvéniles de durée, de sévérité, et de timing différents. Si l’hypothyroïdie juvénile est aussi fréquente au-delà de 4 ans dans les deux groupes de l’étude, les stigmates cliniques d’hypothyroïdie persistante sont plus fréquemment observés chez les enfants nés de mères non supplémentées en iode que chez les autres. De plus, la sévérité des stigmates cliniques (degré d’arriération mentale ; importance du retard de développement statural) démontre que l’hypothyroïdie persistante s’est installée plus précocement chez ertains enfants nés de mères non supplémentées en iode que chez les autres. Dans les formes les plus sévères, l’évolution staturale et le niveau d’intelligence de ces enfants avec hypothyroïdie persistante sont compatibles avec le tableau clinique de crétinisme myxédémateux endémique décrits chez le sujet adulte par les Professeurs François Delange et Jacques Dumont.</p>
<p align="justify"><u>Deuxième partie</u>: étude du métabolisme iodé chez les enfants hypothyroïdiens et mise en évidence de la carence combinée en iode et en sélénium.</p>
<p align="justify">Certains enfants hypothyroïdiens le sont depuis longtemps (depuis la naissance, éventuellement), d’autres le sont transitoirement, sans que leur hypothyroïdie passagère ne laisse de séquelles évidentes en termes de retard statural ou d’arriération mentale.</p>
<p align="justify">Ceux qui sont en hypothyroïdie persistante au-delà de 4 ans ont une fonction thyroïdienne altérée : lorsqu’on leur administre de l’iode, leur glande ne répond pas à cette correction de carence iodée, et ils demeurent profondément hypothyroïdiens. Ce phénomène de non réponse à la correction de la carence iodée n’estpas observé chez les enfants hypothyroïdiens plus jeunes : cela démontre qu’il y a, chez certains enfants, une perte progressive de la capacité fonctionnelle de la thyroïde à répondre à la supplémentation iodée. Ces sujets développent le tableau clinique de crétin myxédémateux endémique.</p>
<p align="justify">On constate que l’hypothyroïdie juvénile recouvre un vaste spectre depuis les cas d’hypothyroïdie transitoire jusqu’aux cas d’hypothyroïdie irréversible, même après correction de la carence iodée.</p>
<p align="justify">Sur base d’hypothèse physiopathologique de cette perte de capacité fonctionnelle de la thyroïde chez certains jeunes enfants, il a été proposé qu’une carence combinée en iode et en sélénium pourrait expliquer ce processus. Une telle carence combinée a été décrite dans notre travail dans la région goitreuse du Nord-Congo, et pas dans d’autres régions non goitreuses du même pays ou dans d’autres endémies goitreuses avec peu de crétinisme myxédémateux endémique (Soudan, Sénégal).</p>
<p align="justify"><FONT size=1>*Thilly Claude-Hector, Delange François, Lagasse Raphael, Bourdoux Pierre, Ramioul L, Berquist Helen, Ermans André-Marie. Fetal hypothyroidism and maternal thyroid status in severe endemic goiter. Journal of Clinical Endocrinology and Metabolism.</FONT></P>
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Localization of targets for regulation of gene expression after ionising radiationAl-Assar, Osama January 1999 (has links)
No description available.
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A solid state laser system for Doppler-free spectroscopy of muoniumBakule, Pavel January 1998 (has links)
No description available.
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