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Génétique des fibroses pulmonaires familiales de l’adulte / Genetics of adult familial pulmonary fibrosisBorie, Raphaël 21 June 2017 (has links)
Environ 10 % des patients atteints de fibrose pulmonaire idiopathique (FPI) ont au moins un apparenté atteint de pneumopathie interstitielle diffuse (PID). Des mutations avaient été mises en évidence sur les gènes codant pour les protéines impliquées dans le métabolisme du surfactant et les protéines du complexe télomérase. Chez l’adulte, les mutations de TERT étaient les plus fréquentes (˜15 %), les mutations de TERC, DKC1 et TINF2 plus rarement retrouvées. Environ 80 % des formes familiales de fibroses pulmonaires chez l’adulte étaient sans cause identifiée. Les objectifs de cette thèse étaient : 1) d’identifier un nouveau gène en cause dans les fibroses pulmonaires familiales de l’adulte inexpliquées, 2) de mieux caractériser le phénotype des patients présentant des mutations de TERT, de TERC ou du nouveau gène mis en évidence.Nous avons sélectionné 35 familles présentant une fibrose pulmonaire familiale pour lesquelles la recherche de mutation TERT, TERC, ABCA3, SFTPB et SFTPC était négative, pour réaliser un séquençage de l’exome. Quatre familles sur les 35 analysées présentaient un variant très rare sur RTEL1 à l’état hétérozygote. La présence des variants a été confirmée par séquençage selon la méthode de Sanger. Ces variants étaient absents des bases de données de contrôles. Les prédictions in silico étaient en faveur du caractère pathogène de ces variants. Les variants co-ségrégeaient avec la maladie dans les familles.L’analyse des variants à partir de la modélisation en 3D de la protéine suggérait un impact fonctionnel des variants sur le site de fixation à l’ATP ou à l’ADN. La taille des télomères des patients étaient raccourcies en comparaison des témoins de la même catégorie d’âge. En 2014, 237 patients avec une fibrose pulmonaire (153 avec une fibrose pulmonaire familiale, 84 avec un syndrome télomère) avaient bénéficié d’un séquençage de TERC et de TERT. Les variants ont été classés comme pathogènes chez 40 patients (16,8 %). Un âge de survenue précoce de fibrose, une macrocytose, ou une thrombopénie étaient significativement associée avec la présence d’une mutation. La probabilité d’une mutation était la plus importante pour les patients de 40-60 ans. La médiane de survie sans transplantation était plus faible pour les patients porteurs de mutations de TERT ou de TERC. Nous avons réalisé un séquençage de l’exome chez 40 autres familles et mis en évidence 5 nouveaux variants de RTEL1 probablement pathogènes in silico. Nous avons par ailleurs mis en évidence 3 autres mutations de RTEL1 dans une cohorte de PID associées à une polyarthrite rhumatoïde. Nous avons colligé les données de 35 patients atteints de PID et porteurs de mutations hétérozygotes de RTEL1. Vingt patients présentaient une FPI (57 %) et 10 une PID secondaire (25,7%). A la différence des mutations de TERT ou TERC, les mutations de RTEL1 étaient associées à moins d’anomalies hématologiques. Par ailleurs, l’expression pulmonaire de la protéine RTEL1 évaluée par immuno-histochimie et de l’ARNm par PCR était équivalente chez les patients porteurs de mutations RTEL1, de TERT ou atteints de FPI sans mutation. Nous avons identifié et confirmé l’implication d’un nouveau gène, RTEL1, dans environ 10 % des fibroses pulmonaires familiales. La présence d’une macrocytose, d’une thrombopénie ou d’un âge jeune en présence d’une forme familiale de fibrose est prédictive de la présence d’une mutation de TERT ou de TERC. La pénétrance des maladies hématologiques semble plus faible pour les mutations de RTEL1 que pour celles de TERT ou TERC dans notre cohorte recrutée sur l’atteinte pulmonaire. Les mutations de TERT ou de RTEL1 sont fréquemment associées à des PID secondaires / About 10% of patients with idiopathic pulmonary fibrosis (IPF) have at least one relative with interstitial lung disease (ILD). Mutations had been reported on the genes encoding for the proteins involved in the surfactant metabolism and in the telomerase complex In adults, TERT mutations were the most frequent (˜15%), mutations of TERC, DKC1 and TINF2 more rarely found. Approximately 80% of the familial forms of pulmonary fibroses in adults were unidentified. The objectives of this work were: 1) to identify a new gene involved in unexplained adult familial pulmonary fibrosis, 2) to better characterize the phenotype of patients with mutations of TERT, TERC or the new gene detected. We selected 35 families with familial pulmonary fibrosis for which the TERT, TERC, ABCA3, SFTPB and SFTPC mutation search was negative, to perform exome sequencing. Four of the 35 families analyzed showed a very rare variant on RTEL1 in the heterozygous state. The presence of the variants was confirmed by Sanger sequencing. These variants were absent from the control databases. In silico predictions were in favor of the pathogenicity of these variants.In families, the variants co-segregated with the disease. In 3D modeling, analysis of the variants suggested a functional impact at the ATP or DNA binding site. The telomere length of carriers of the mutations was shortened compared to controls in the same age group. In 2014, 237 patients with pulmonary fibrosis (153 with familial pulmonary fibrosis, 84 with telomere syndrome) were sequenced for TERC and TERT. The variants were classified as pathogenic in 40 patients (16.8%). An early age of diangosis, macrocytosis, or thrombocytopenia were significantly associated with the presence of a mutation.The probability of a mutation was greatest for patients aged 40-60 years. The median survival without transplantation was lower for patients with TERT or TERC mutations.We performed a sequencing of the exoma in 40 other families and showed 5 new variants of RTEL1 probably pathogenic in silico. We also demonstrated 3 other mutations of RTEL1 in a cohort of ILD associated with rheumatoid arthritis. We collected data from 35 patients with ILD carriers of RTEL1 heterozygous mutations. Twenty patients had IPF (57%) and 10 a secondary ILD (25.7%). Unlike mutations within TERT or TERC, RTEL1 mutations were associated with fewer hematological abnormalities.Furthermore, the pulmonary expression of the RTEL1 protein evaluated by immunohistochemistry and mRNA by PCR was equivalent in patients carriers of RTEL1 or TERT mutations or IPF without mutation. We identified and confirmed the implication of a new gene, RTEL1, in about 10% of familial pulmonary fibroses. The presence of macrocytosis, thrombocytopenia or a young age is predictive of the presence of a mutation within TERT or TERC. The penetrance of hematological diseases appears to be lower for RTEL1 mutation carriers than for TERT or TERC mutation carriers in our cohort of ILD patient. Mutations of TERT or RTEL1 are frequently associated with secondary ILD
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Electrochemical rate measurements for the reduction of tert-nitrobuutane and relation to modern electron transfer theoryCorrigan, Dennis Arthur. January 1979 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1979. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 180-187).
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Derivatives of trifluorovinylsulfur pentafluoride and F-(tert-butyl) hypochloriteCanich, Jo Ann Marie 01 January 1984 (has links)
Trifluorovinylsulfur pentafluoride dimerizes to (SF5CFCF2)2 in the presence of cesium fluoride. Two derivatives of trifluorovinylsulfur pentafluoride, SF5CF(CF3)C(O)F and SF5CF(CF3)C(O)NH2, were used to prepare the new compounds, SF5CF(CF3)CO2H and SF5CF(CF3)CN, respectively. The first was prepared by reacting the SF5-acid fluoride with water, while the second involved the abstraction of water from the SF5-amide using P4O10. The attempted preparation of a bis-pentafluorosulfur ketone and a pentafluorosulfur containing acid anhydride were unsuccessful.
Selected transition and post transition metal chlorides and elements undergo oxidative displacement and oxidative addition reactions with F-(tert-butyl) hypochlorite, (CF3)3COCl, to form new F-(tert-butoxides). Preliminary studies with selected aromatic systems were also carried out.
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Extra-nuclear telomerase reverse transcriptase (TERT) regulates glucose transport in skeletal muscle cellsShaheen, F., Grammatopoulos, D.K., Muller, Jurgen, Zammit, V.A., Lehnert, H. 2014 June 1923 (has links)
Yes / Telomerase reverse transcriptase (TERT) is a key component of the telomerase complex. By lengthening telomeres in DNA strands, TERT increases senescent cell lifespan. Mice that lack TERT age much faster and exhibit age-related conditions such as osteoporosis, diabetes and neurodegeneration. Accelerated telomere shortening in both human and animal models has been documented in conditions associated with insulin resistance, including T2DM. We investigated the role of TERT, in regulating cellular glucose utilisation by using the myoblastoma cell line C2C12, as well as primary mouse and human skeletal muscle cells. Inhibition of TERT expression or activity by using siRNA (100nM) or specific inhibitors (100nM) reduced basal 2-deoxyglucose uptake by ~50%, in all cell types, without altering insulin responsiveness. In contrast, TERT over-expression increased glucose uptake by 3.25-fold. In C2C12 cells TERT protein was mostly localised intracellularly and stimulation of cells with insulin induced translocation to the plasma membrane. Furthermore, co-immunoprecipitation experiments in C2C12 cells showed that TERT was constitutively associated with glucose transporters (GLUTs) 1, 4 and 12 via an insulin insensitive interaction that also did not require intact PI3-K and mTOR pathways. Collectively, these findings identified a novel extra-nuclear function of TERT that regulates an insulin-insensitive pathway involved in glucose uptake in human and mouse skeletal muscle cells.
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Perfil de expressão dos genes MYC, MYCN, TERT, ASPM e PRAME em Meduloblastoma / Expression profile of genes MYC, MYCN, TERT, ASPM and PRAM in MedulloblastomaVulcani-Freitas, Tânia Maria [UNIFESP] 28 April 2010 (has links) (PDF)
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Previous issue date: 2010-04-28 / Meduloblastoma (MB) é o tumor maligno de sistema nervoso central (SNC) mais comum em criança, compreendendo 20% dos tumores primários de SNC e 40% dos tumores cerebelares da infância. Devido sua forte tendência metastática, o tratamento padrão pós-operatório inclui radio e quimioterapia, cujo impacto causa distúrbios endócrinos e de crescimento, e disfunção neurocognitiva a longo prazo. Frente a esses efeitos negativos, muitas pesquisas em meduloblastoma têm sido realizadas com intuito de obter conhecimento biológico desses tumores para tentar identificar fatores prognósticos moleculares que possam orientar os tratamentos, tornando-os mais específicos e menos agressivos. Alguns estudos em MB têm sugerido que a expressão do oncogene MYC está associada com diminuição da sobrevida e sua superexpressão com maior agressividade do tumor. Por isso, MYC pode ser um indicador importante de prognóstico, além de modulador do comportamento desta doença. Enquanto o gene MYC é expresso em uma variedade de tecidos, a expressão de MYCN, outro membro da família MYC, é restrita a estágios precoces do desenvolvimento embrionário de alguns tecidos apenas, entre eles, o sistema nervoso central e periférico, sendo um mediador importante dos efeitos de ativação na proliferação de células precursoras cerebelares. Dessa forma, quando a expressão de MYCN está desregulada, ela aumenta a tumorigenicidade dessas células podendo dar origem ao MB. Além disso, o gene MYC também é considerado importante regulador da transcrição TERT, gene que codifica uma subunidade catálica de da telomerase, enzima importante para carcinogênese e imortalização de células neoplásicas. A atividade anormal da telomerase está presente em 90% dos cânceres e o aumento de sua atividade está associado a eventos clínicos desfavoráveis. Outro gene importante é o ASPM (abnormal spindle-like microcephaly associated) que desempenha função fundamental na neurogênese e proliferação celular durante o desenvolvimento cerebral. Esse gene codifica uma proteína de centrossomo e fuso mitótico que permite a divisão celular simétrica em células neuroepiteliais durante o desenvolvimento e aumento do tamanho cerebral. Alterações em ASPM é a causa mais comum de microcefalia primária em humanos e de falha de segregação, induzindo a aneuploidias e instabilidade genética. Além desses genes, outro gene estudado recentemente, como alvo em xv imunoterapia, é o gene PRAME que codifica um antígeno tumoral que está presente em vários tumores, incluindo meduloblastoma. O gene PRAME possui baixa ou ausência de expressão em tecidos normais, por isso é pode ser um forte candidato como alvo em imunoterapia, que é um tratamento menos tóxico. OBJETIVOS: O objetivo desse estudo foi investigar a expressão dos genes MYC, MYCN, TERT, ASPM e PRAME em fragmentos tumorais de meduloblastoma de crianças e tentar correlacionar com os parâmetros clínicos e verificar se há correlação de MYC, MYCN, TERT entre si, uma vez que estão correlacionados. MÉTODOS: Análise de expressão gênica foi realizada através de PCR quantitativa em tempo real, utilizando sistema SYBR Green, em 37 amostras tumorais de crianças, com média de idade de 8 anos. Para comparação de perfil de expressão foi usada duas amostra de cérebro normal. A análise estatística foi realizada nos programas Graph Pad Prism 4 e VassarStats RESULTADOS: Todas nossas amostras superexpressaram o gene MYCN com valor de quantificação relativa (RQ) mediana igual a 31 com p=0.001; assim como, todas nossas amostras também superexpressaram o gene ASPM com mediana igual a 586, p<0.0001. Do total de amostras, 95%, 81% e 84% superexpressaram TERT, MYC e PRAME respectivamente, sendo os valores de RQ (mediana) iguais a 322, p=0.01; 9.2, p<0.0001; 33, p<0.0001. Apesar da elevada expressão dos genes estudados na maioria das amostras estudadas, houve apenas correlação estatística entre a superexpressão de MYCN (p=0.008) e os pacientes que foram a óbito, e de TERT e os pacientes que recidivaram (p=0.0431). Não encontramos outra correlação estatística entre a superexpressão dos genes e as características clínicas dos pacientes. CONCLUSÃO: Os genes MYC, MYCN e TERT estavam superexpressos nas amostras de meduloblastoma analisadas em uma freqüência muito superior ao demonstrado na literatura, o que sugere que esses três genes podem ajudar na identificação de tumores agressivos, uma vez que o pognóstico desses pacientes continua baseado apenas em parâmentros clínicos. A superexpressão de ASPM em todas as amostras estudadas sugere que este gene pode estar envolvido na origem de MB, como parte da neurogênse anormal durante o desenvolvimento embrionário, porém estudoas funcionais devem ser realizados para confirmar essa hipótese. Por fim, o gene PRAME pode ser candidato à marcador de célula tumoral em MB, podendo no futuro ser candidato como alvo em imunoterapias. / To investigate the expression of genes MYC, MYCN and TERT in tumor fragments of pediatric medulloblastoma and correlate gene expression profiles with clinical parameters. Analysis of gene expression was performed by quantitative PCR real time in 37 tumor samples and correlated with clinical and pathological data. All 37 samples overexpressed MYCN gene (p= 0.001), 95% and 84% of the samples overexpressed TERT and MYC, respectively (p<0.0001). Twenty nine (78%) of all samples had concomitant high expression of MYC, MYCN and TERT genes together. Seventeen (59%) were high-risk classification, 10 (34%) were metastatic (M+) stage, two (7%) were anaplastic or largecell/ anaplastic subtype, eight (28%) of patients relapsed, beyond thirteen (45%) suffered partial surgical resection. and fourteen (48%) died. We found correlation between MYC, MYCN and TERT expression (p<0.0001). The identification of a subgroup with concomitant overexpression of the three investigated genes suggests the possibility of using more than one aspect of molecular indicative of unfavorable prognosis that characterizes the group with poor outcome. However, in future this may be enhanced by targeted therapy for the product TERT as proposed in some neoplasms. The identification of molecular events in the medulloblastoma categorization aims to help at-risk groups moving towards individualized medicine. / TEDE / BV UNIFESP: Teses e dissertações
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Caracterização bioquimica e molecular do componente transcriptase reversa da telomerase de Leishmania spp / Biochemical and molecular characterization of the Leishmania spp. telomerase reverse transcriptase componentGiardini, Miriam Aparecida 14 June 2007 (has links)
Orientador: Maria Isabel Nogueira Cano / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-10T06:46:56Z (GMT). No. of bitstreams: 1
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Previous issue date: 2007 / Resumo: Telômeros são complexos DNA-proteínas que protegem os cromossomos eucarióticos da degradação, garantindo estabilidade genômica. As seqüências teloméricas são ricas em G e apresentam uma protrusão 3¿ simples-fita que se estende em direção ao terminal cromossômico. Em Leishmania, os telômeros são compostos pela seqüência repetida 5¿-TTAGGG-3¿ e são replicados pela telomerase, a principal responsável pela manutenção dos terminais cromossômicos em eucariotos. Além de replicar os telômeros, o complexo holoenzimático da telomerase, composto pela transcriptase reversa da telomerase (TERT), pelo RNA da telomerase (TER) e por proteínas associadas, também atua como parte de um complexo de ordem maior que protege os terminais teloméricos. O entendimento do mecanismo de regulação da manutenção telomérica será de grande valor científico e poderá levar ao descobrimento de algum alvo potencial para o desenvolvimento de novas drogas anti-leishmania. Com esse objetivo, identificamos, clonamos e caracterizamos o gene que codifica o componente TERT em Leishmania spp.. O alinhamento múltiplo das seqüências através do programa ClustalW demonstrou que as telomerases de Leishmania apresentam muito mais homologia entre si do que com as proteínas de outros kinetoplastídeos e eucariotos. Experimentos de caracterização indicaram que a seqüência putativa do gene da telomerase de Leishmania localiza-se provavelmente em cópia única nos maiores cromossomos. Um único transcrito de RNA mensageiro foi encontrado nos promastigotas. Análises filogenéticas sugeriram que a telomerase de Leishmania pode representar uma ligação entre os mais antigos e os mais novos ramos das telomerases. Além disso, proteínas recombinantes foram expressas em sistema bacteriano, tornando possível a produção de anticorpos policlonais em coelhos. Experimentos de ¿Western blotting¿ e imunoprecipitação de cromatina indicaram que o anticorpo foi capaz de reconhecer a proteína nativa e que a telomerase de L. amazonensis interage in vivo com a seqüência telomérica rica em G. A atividade de telomerase de L. amazonensis foi purificada utilizando-se uma combinação de colunas cromatográficas. Testou-se a atividade enzimática em cada passo da purificação utilizando-se o ensaio ¿Two-tube TRAP¿. Os resultados mostraram que a atividade enzimática é encontrada nas frações purificadas pelas cromatografias de troca iônica, de afinidade por Heparina e de gel filtração. A atividade foi altamente enriquecida após a purificação por afinidade utilizando um oligonucleotídeo de DNA telomérico rico em G. Quando foi utilizado um oligorribonucleotídeo 2¿O-metil complementar à putativa seqüência molde do TER de Leishmania como ligante na cromatografia de afinidade, pouca ou nenhuma atividade enzimática foi eluída da resina, sugerindo que a interação entre a telomerase de L. amazonensis e este oligorribonucleotídeo é tão forte que não permite sua dissociação nas condições de eluição gentis necessárias para manter a atividade enzimática. Formas procíclicas de Trypanosoma brucei foram utilizadas para a construção do sistema ¿PTP-tagging¿, no intuito de futuramente purificar o complexo holoenzimático da telomerase. Em paralelo, ensaios de ¿primer extension¿ foram padronizados e identificou-se uma seqüência candidata ao gene do RNA da telomerase de T. brucei. Também foi identificada e clonada em L. amazonensis, uma seqüência homóloga à PinX1 humana, descrita como uma proteína que interage diretamente com a TERT humana e considerada um inibidor natural da atividade de telomerase / Abstract: Telomeres are protein-DNA complexes that protect linear chromosomes from degradation, providing genomic stability. The telomeric sequences are G-rich and contain a 3¿ single-stranded region that protrudes toward the chromosome end. In Leishmania, the telomeric DNA is composed by the conserved 5¿-TTAGGG-3¿ repeated sequence and it is replicated by telomerase. Telomerase is responsible for maintaining chromosome ends in most eucaryotes by adding new telomeric sequences to the G-rich strand. Besides replicating telomeres, the telomerase holoenzyme complex, composed by the reverse transcriptase component (TERT), the telomerase RNA (TER) and associated proteins, also works as part of the higher order complex that protects telomeric ends. Understanding the regulation of the telomeric maintainance mechanism may allow the discovery of potential targets to the development of new antileishmania drugs. Therefore, we identified, cloned and characterized the TERT gene in Leishmania spp.. A ClustalW multiple-sequence alignment demonstrated that the Leishmania telomerases show greater homology with each other than with the proteins of other kinetoplastids and eukaryotes. Characterization experiments indicated that the putative Leishmania TERT gene was probably located in single copy at the largest chromosomes. A single messenger RNA transcript was found in promastigotes. Phylogenetic analysis suggested that Leishmania telomerase might represent a liaison between the oldest and the newest branches of telomerases. Besides that, recombinant proteins were expressed in bacterial system, allowing production of anti-LaTERT polyclonal serum in rabbits. Western blotting and chromatin immunoprecipitation assays indicated that the anti-LaTERT serum was able to recognize a native protein in nuclear and total extracts of the parasite and that L. amazonensis telomerase interacts in vivo with the G-richtelomeric sequence. We have also purified the L. amazonensis telomerase activity in order to better understand its biochemical features. Protein extracts of L. amazonensis containing telomerase activity were purified using combined chromatographic columns. Enzyme activity was tested in each purification step using the ¿Two-tube TRAP¿ assay. The results showed that enzyme activity is found in fractions purified by ion exchange (DEAE), Heparin affinity and gel filtration chromatographic methods. The activity was greatly enriched after affinity purification using a G rich telomeric DNA oligonucleotide as the ligand. When a 2¿O-methyl oligoribonucleotide complementary to the putative L. amazonensis TER template was used as a ligand in the affinity purification, little or no enzyme activity was eluted from resin, suggesting that the interaction between L. amazonensis telomerase and this oligoribonucleotide is too strong that disables its dissociation under the gentle elution conditions necessary to maintain enzyme activity. In order to identify the telomerase holoenzyme components, procyclic forms of Trypanosoma brucei were used to construct the PTP-tagging system. ¿Primer extension¿ reactions were also done in order to isolate and sequence an RNA candidate for the telomerase RNA gene in T. brucei. In addition, we have cloned a L. amazonensis homologue of the human PinX1 protein, previously known as a hTERT-interacting factor and as a potent telomerase inhibitor / Doutorado / Genetica de Microorganismos / Doutor em Genetica e Biologia Molecular
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Biological Effects and Action Mechanisms of Dietary CompoundsSukamtoh, Elvira 09 July 2018 (has links)
The food that we consume contain many dietary compounds which are biologically active. In this thesis we will discuss the biological effects of dietary compounds and the mechanisms behind their activities.
First, we studied on the anti-metastatic effects of curcumin, a dietary compound derived from turmeric, through lymphangiogenesis inhibition. Curcumin inhibited vascular endothelial growth factor-C (VEGF-C)-induced lymphangiogenesis in vivo and in vitro. Curcumin inhibited lymphangiogenesis, in part through suppression of proliferation, cell cycle progression and migration of lymphatic endothelial cells. Curcumin inhibited expressions of VEGF receptors (VEGFR2 and VEGFR3), as well as down-stream signaling such as phosphorylation of ERK and FAK. Finally, curcumin sulfate and curcumin glucuronide, two major metabolites of curcumin in vivo, had little inhibitory effect on proliferation of HMVEC-dLy cells. Our results demonstrate that curcumin inhibits lymphangiogenesis in vitro and in vivo, which could contribute to the anti-metastatic effects of curcumin.
Next, we investigated the mechanisms underlying the cytotoxic activity of tert-butylhydroquinone (TBHQ), a widely used synthetic food antioxidant. Here we found that the biological effects of TBHQ are mainly mediated by its oxidative conversion to a quinone metabolite tert-butylquinone (TBQ). Co-addition of cupric ion (Cu2+) enhanced, whereas ethylenediaminetetraacetic acid (EDTA) suppressed the oxidative conversion of TBHQ to TBQ, and the biological activities of TBHQ in MC38 colon cancer cells. Finally, a structure and activity relationship study was done and together, these results suggest that the biological activities of TBHQ and other para-hydroquinones are mainly mediated by their oxidative metabolism to generate more biologically active quinone metabolites.
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Adsorption Removal of Tertiary Butyl Alcohol from Wastewater by ZeoliteButland, Tricia Dorothy 29 April 2008 (has links)
Tertiary butyl alcohol (TBA) is used as a fuel oxygenate and is the main breakdown component of methyl tert butyl ether (MTBE). As such, TBA is found in water systems through storage leaks and spills, presence of MTBE in the water, and as an impure byproduct of MTBE-blended fuels. It presents several health hazards and is a suspected carcinogen. Studies involving aquatic life, mice and rats indicate that TBA is a concern at low concentrations. Wastewater removal of tert butyl alcohol (TBA) has been limited to methodology used by MTBE or by anaerobic or aerobic methods. Neither set of techniques is applicable to TBA due to its long biological degradation period, its very specific conditions for anerobic or aerobic treatment, and its low Henry's law constant, low transformation rate, and its high mobility.
The main goal of this project was to determine the adsorption capabilities of different zeolites for TBA. A comparison to previous work done with powdered zeolites and MTBE is shown in the following Chapters. Batch systems of TBA and several different zeolites were examined to determine the best zeolites for TBA adsorption. As shown in Chapter 3, the best zeolites for TBA adsorption over an equilibrium time of 48 hours were silicalite and HiSiv 3000 pellets. Using the two chosen zeolites, silicalite and HiSiv 3000, adsorption isotherms were created and compared against MTBE data using the same data.
The final portion of this project included a continuous system consisting of a zeolite column and a steady flow rate of TBA. The zeolite columns consisted of sole silicalite, sole HiSiv 3000, and different proportions of the two zeolites in the same column. All column experiments were run at similar conditions with variation in the adsorbent bed lengths for easy comparison between the resulting breakthrough curves. At the 3-cm bed length, the zeolite columns outperformed the activated carbon column; however, there was no distinct difference between the zeolite columns. In the 6-cm bed length experiments, there were apparent differences between the two zeolite breakthrough curves. The 9-cm column did not differentiate between the zeolites.
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Synthèse, fonctionnalisation et étude conformationnelle de calixarènes comportant 7, 9, 10 et 12 unités / Synthesis, fonctionnalisation and conformational studies of p-tert-butylcalix[7, 9, 10 and 12]arenesFerchichi, Mouna 27 May 2011 (has links)
Le travail de cette thèse a permis tout d’abord d’aboutir à un protocole simplifié pour la synthèse des p-tert-butylcalix[7] et [9]arènes, composés jusqu’à lors difficilement préparables. Ces macrocycles ont été obtenus en grosse quantité, de l’ordre de la dizaine de gramme. Il faut également noter que cette synthèse sur grande échelle permet d’obtenir les p-tert-butylcalix[10] et [12]arènes avec des rendements modestes mais une simplicité remarquable. A partir de ces calixarènes, deux voies principales de per-fonctionnalisation ont été mises en oeuvre : La réaction de Williamson, consistant à former des éthers, et l’estérification via l’utilisation d’anhydrides. Au total, ce sont 10 nouveaux calixarènes fonctionnalisés qui ont été obtenus. Le comportement dynamique et conformationnel des calix[9]arènes originaux a été évalué en solution et à l’état solide. Dans le cas où cela a été possible, la détermination des constantes de vitesse et d’énergie libre des mouvements conformationnels a montré que ces calix[9]arènes fonctionnalisés étaient très mobiles. En outre, trois nouvelles structures RX ont été obtenues et ont confirmé que ces macrocycles adoptaient une conformation désordonnée. En l’état, ces nouveaux calixarènes ne sont pas des candidats de choix pour devenir des hôtes moléculaires efficaces. Toutefois, ce travail a permis d’améliorer nos connaissances sur des structures dérivées de p-tert-butylcalix[n]arènes (n = 7, 9, 10 et 12) peu étudiés jusqu’à présent / The work of this thesis allowed to propose a simplified procedure for the synthesis of p-tertbutylcalix[ 7] and [9]arenes, which were hardly synthesizable until now. Those macrocycles were obtained in a large amount, about a dozen of grams. It’s important to emphasize that this large scale synthesis allow to obtain the p-tert-butylcalix[10] and [12]arenes with moderate yields but in a straight and simple procedure. From these calixarenes, two main ways of per-functionalization were attempted: Williamson reaction, consisting in forming ethers and esterification by using anhydrides. Totally, 10 new functionalized calixarenes were obtained. Their dynamic and conformational behaviors in solution as well as in the solid state were explored. The determination of the rate constants and of the free energy barrier of the conformational motion has shown that those compounds were mobile. Moreover, three original X-Ray structures were obtained and have revealed that those macrocycles adopted a disordered conformation. At this point, those new calixarenes are not well designed to act as efficient molecular host. However, this work allowed to improve our knowledges on structures made from the p-tert-butylcalix[n]arene (n = 7, 9, 10 and 12), a skeleton rarely described and studied up to now
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Performance Study on the Treatment of MTBE-Borne Waste Gas by Activated Sludge Aeration and Biotrickling Filtering ProcessesSu, Li-Chun 14 June 2005 (has links)
In this study, a laboratory-scale activated sludge reactor and a biotrickling filter were constructed to study the removal of methyl tert-butyl ether (MTBE) from air vented from contaminated sites.
The activated sludge tank (0.4 m¡Ñ0.4 m cross-sectional area, 3.0 m height, and 480 L total volume) was made by acrylic resin. A mixed liquor suspended solids (MLSS) concentration of 2000-3000 mg/L was maintained in the experimental mixed liquor and the sludge was acclimated for 30 days under selected conditions of a Food to Microorganism Ratio (F/M) of 0.3 g BOD/(g MLSS¡Dday) and an influent gas MTBE concentration (C0) of 180 mg/Am3 (@27oC). Results on performance tests show that an average MTBE removal efficiency of 93.6% was obtained with the operation conditions of C0 of 610 mg/Am3 (@27oC), volumetric aeration rate of 0.063 m3/m3¡Dmin, MLSS of 2600 mg/L, and submerged liquid depth of 1.0 m.
The biotrickling filter was made by combining two same type of acrylic resin columns (each 0.2 m inner diameter, 2.0 m height, and packed with 900 pieces of polypropylene Pall rings to a height of 1.35 m) in series for the test gas flow and in-parallel for the trickling liquid flow. Each test was operated for 8 hours to reach a steady state for a set of selected conditions (gas flow rate 0.050 m3/min and superficial gas velocity 0.027 m/s, trickling liquid flow rate 0.004 m3/min and pH: 6.8-7.2, and liquid/gas flow ratio: 80 L/m3). Results show that the MTBE removal efficiencies from the influent gas were 40%, 22% and 15%, respectively, with C0 of 50,100 and 230 mg/Am3 (@27oC).
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