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1
Denis, Valérie. "Régulation des gènes de la biosynthèse des purines chez la levure Saccharomyces Cerevisiae." Bordeaux 2, 1999. http://www.theses.fr/1999BOR28660.
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Fairhurst, Neil. "Synthesis of modified purines." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46294.
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Petrilli, Camila Lopes. "Regulação da atividade da glândula pineal por estimulação purinérgica." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-01052013-140517/.
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A biossíntese de MEL pela pineal envolve a conversão da serotonina a NAS pela enzima AA-NAT, seguida demetilação da NAS pela enzima HIOMT gerando a MEL. A ativação β-adrenérgica é essencial e a co-estimulação de receptores P2Y1 potencia a produção de NAS induzida por noradrenalina. Neste trabalho avaliamos o efeito da estimulação de receptores P2Y1 sobre a produção de MEL induzida pela estimulação β-adrenérgica. A co-estimulação purinérgica com ADP, levou a potenciação da produção de NAS induzida por ISO e a inibição do conteúdo de MEL de maneira dependente de concentração. Em extratos nucleares de pineais estimuladas com ADP, a translocação nuclear de AP-1 foi observada, não havendo alteração significativa na translocação nuclear dos dímeros NF-κB p50/p50 e p50/RelA. PDTC, inibidor de NF-κB, não alterou o conteúdo de NAS e MEL em pineais em cultura estimuladas com ISO e ADP. A expressão gênica e a atividade enzimática de AA-NAT e HIOMT não foram alteradas pela co-estimulação com ISO e ADP. O bloqueio seletivo dos receptores P2Y1 por A3\'P5\'P inibiu de maneira dependente de concentração o efeito potenciador do ADP sobre a produção de NAS induzida por ISO, mas não reverteu a inibição observada nos níveis de melatonina. Estes resultados apontam para um mecanismo diferencial de modulação da produção de NAS e MEL abrindo novas perspectivas ao estudo dos mecanismos regulatórios da produção de MEL e seus metabólitosThe biosynthesis of MEL by the pineal gland involves the conversion of serotonin to NAS by the enzyme AA-NAT, followed by methylation of NAS by the enzyme HIOMT generating MEL. The activation of β-adrenergic receptors is essential and the co-stimulation of P2Y1 receptors potentiates noradrenaline-induced NAS production. In this study we evaluated the effect of P2Y1 receptors stimulation on the production of MEL synthesis induced by β-adrenergic stimulation. Purinergic co-stimulation with ADP potentiated ISO-induced NAS production and inhibited melatonin content in a concentration dependent manner. In nuclear extracts from stimulated pineal glands with ADP, the nuclear translocation of AP-1 was observed, with no significant change in the nuclear translocation of the NF-κB dimers p50/p50 and p50/RelA. PDTC, an inhibitor of NF-κB, did not alter the content of NAS and MEL in cultured pineal glands co-stimulated with ISO and ADP. ISO and ADP co-stimulation did not alter the transcript and enzyme activity of AA-NAT and HIOMT. The selective blockade of P2Y1 receptors by A3\'P5\'P inhibited, in a concentration-dependent manner, the potentiating effect of ADP on ISO-induced NAS production but did not change the inhibition observed on MEL levels. These results suggest a differential mechanism on the modulation of NAS and MEL production opening new perspectives to the study of the regulatory mechanisms involved in the biosynthesis of MEL and its metabolites
4
Worthington, Rebecca A. (Ann). "Structure-function studies of P2X receptors." Thesis, The University of Sydney, 2001. https://hdl.handle.net/2123/27719.
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P2X receptors are fast, ATP-gated cation ion channels. To date seven subtypes of P2X receptors
have been cloned and identified, PZXH. The membrane topology of the P2X subunit consists of
intracellular amino- and carboxy-termini, two transmembrane spanning domains and a large
extracellular loop. Despite similar membrane topology, within this family of receptors the P2X
subtypes possess different functional characteristics. They exhibit different sensitivities to
agonists and antagonists, are modulated differently by extracellular ions, and have different pore
forming abilities. The regions that are responsible for differences in function between P2X
subtypes have not been elucidated.
This thesis aims to further knowledge regarding the relationship between the structure of the P2X
family and differences in the function of the various receptor subtypes.
Examination of the primary structure of the P2X receptor family led to the identification of
epitope regions suitable for antibody production. This suite of antibodies was tested for
specificity and the distribution of P2X receptors was examined in a range of rat tissues and two
cell lines.
The pathophysiological involvement of the P2X7 receptor was examined in B-CLL patients. Two
polymorphisms as well as a loss of function mutation were identified in both normal and
leukaemic populations.
The site of agonist binding is believed to be within the extracellular loop. Examination of the
primary structure of the human cytolytic receptor P2X7 led to the identification of two noncontiguous regions that could potentially be involved in binding ATP. Three amino acid residues
that lie within the extracellular loop were targeted and their involvement in ATP binding was
determined. Two lysine residues at positions 193 and 31 1 and a proline residue at 210 were each
exchanged with alanine. An abolition of function of human receptors with mutations at positions
193 or 311 was observed, consistent with a disruption of the ATP binding domain, although
alterations in transduction or gating cannot be dismissed. The P2X receptor appears to be
comprised of a trimeric subunit arrangement, and Hill coefficients of between 1 and 3 reported
for ATP binding suggest that there is more than one ATP binding site per functional receptor.
Modelling of the putative binding cleft of the hP2X7 subunit was performed and the residues
important for ATP binding were highlighted. The fimctional trimeric receptor appears to possess
three intersubunit ATP binding sites.
In an attempt to isolate regions of the extracellular domain that contribute to or control various
channel properties, chimaeras between subtypes P2X], P2X4 and P2X7 were constructed and their
properties examined. Each of the six chimaeras has been shown to be correctly inserted into the
cell membrane and functional. These constructs will continue to be investigated and form the
basis for extensive future work.
5
Ghérardi, Arnaud. "Toxoplasma gondii : étude de la purine nucléoside phosphorylase." Lyon 1, 2001. http://www.theses.fr/2001LYO1T208.
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La 4e de couverture indique : "Toxoplasma gondii est un protozoaire Apicomplexa responsable de toxoplasmose congénitale et cérabrale. Cette dernière est une importante cause de morbidité et de mortalité chez l'immunodéprimé. Comme la majorité des protozoaires, T. Gondii est incapable de synthétiser ses propres purines et dépend donc entièrement de celles de son hôte. Il dispose des enzymes pour interconvertir celles-ci de façon à former les bases puriques qui intégreront divers métabolimes et constitueront les acides nucléiques. Le dosage de six enzymes de la voie des purines a montré que la purine nucléoside phosphorylase (PNP Ec 2. 4. 2. 1) présentait l'activité enzymatique la plus élevée dans le cerveau murin et dans la forme tachyzoi͏̈te de la souche ME49 du parasite isolé de culture cellulaire. L'enzyme de cerveaux de souris saines et de souris parasitées par la souche avirulente DUR de T. Gondii a été purifiée d'un facteur 40. La PNP de tachyzoi͏̈tes de la souche virulente RH et avirulente ME49 isolés de culture cellulaire a été purifiée d'un facteur 11 et la détermination des paramètres cinétiques montre une différence entre l'enzyme du parasite et celle de l'hôte. Des composés chimiques inhibiteurs de la PNP de protozoaires et des composés de formules originales, synthétisés par le laboratoire de Chimie Organique, ont été testés, et l'activité enzymatique de l'enzyme a été dosée par chromatographie liquide haute performance afin de déterminer les IC50 et les Ki des inhibiteurs. La révélation histoenzymatique par précipitation du plomb a été réalisée. L'activité PNP sur des coupes de kyste cérébral de souris et sur des tachyzoi͏̈tes de la souche ME49 de T. Gondii isolés de culture cellulaire a été mise en évidence par microscopie électronique. La localisation de la PNP est cytoplasmique et est particulièrement importante dans les tachyzoi͏̈tes par rapport à leur cellules hôtes. Une intense activité intracytoplasmique péri-membranaire a été observée dans ces formes. "
6
Kahn, Kalju. "Kinetic and mechanistic characterization of the urate oxidase reaction /." free to MU campus, to others for purchase, 1998. http://wwwlib.umi.com/cr/mo/fullcit?p9924895.
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Wong, Cecilia Sui Si. "A study of the purinergic receptors : A1R and P2Y1R in their homodimerization and receptor signaling /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?BICH%202005%20WONG.
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Tyagi, Surendera Kumar. "Electrochemical and enzyme-catalyzed oxidation chemistry of some biologically important purine derivatives (uric acid, 9-B-D-ribofuranosyluric acid and xanthosine) /." Full-text version available from OU Domain via ProQuest Digital Dissertations, 1986.
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9
Longthorne, Darren Stuart. "Thieno-extended purines and related ring systems." Thesis, University of Salford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261839.
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Oliveira, Lisandre de. "Métodos em nutrição de ruminantes: uso de índices fecais para estimar consumo e estimativa da síntese proteica microbiana ruminal." Universidade Federal de Santa Maria, 2009. http://repositorio.ufsm.br/handle/1/10733.
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Conselho Nacional de Desenvolvimento Científico e TecnológicoThis study was carried out to evaluate methods in ruminant nutrition: use of fecal index to estimate intake and use of purine or purine derivatives to estimate rumen microbial protein synthesis. Data from three digestibility trials conducted with castrated male lambs fed ryegrass (Lolium multiflorum, Lam) or Cynodon (Cynodon dactylon var dactylon) at different levels of intake were compiled. Intake data were related to faecal excretion of different chemical compounds through regression analysis. Significant regressions with high R2 were used to calculate estimated intake values, which were compared to observed values by paired t test. Organic matter (OM) intake (g/day) had significant (P<0.01) relation to faecal excretion (g/day) of N and/or acid detergent fiber (ADF) in ryegrass trial (R2 varied from 0.69 to 0.85) while N, ADF and neutral detergent fiber (NDF) had significant (P<0.01) relation to OM intake in Cynodon trials (R2 varied from 0.51 to 0.56). It is concluded that faecal excretion of N and/or ADF had high potential to estimate intake by grazing animals. Rumen microbial protein synthesis estimated either by duodenal purines or urine purines derivatives was different (P<0.01). Moreover, these estimates were highly affected by purines:microbial N proportion used in calculations.
O objetivo deste trabalho foi avaliar métodos em nutrição de ruminantes: o uso de índices fecais para estimar consumo e uso de purinas no duodeno ou de derivados de purinas na urina para estimar a síntese de nitrogênio microbiano ruminal. Foram compilados dados de três ensaios de digestibilidade in vivo utilizando ovinos machos castrados não fistulados ou fistulados no duodeno alimentados com azevém (Lolium multiflorum, Lam) ou capim-paulista (Cynodon dactylon var dactylon) fornecidos verde a diferentes níveis de consumo. Os dados de consumo foram relacionados à excreção fecal de diferentes componentes químicos. As equações de regressão com coeficientes de correlação mais significativos foram utilizadas para calcular consumos estimados, os quais foram comparados pelo teste t para dados pareados com os consumos observados. O consumo de MO foi significativamente (P<0,01) relacionado com a excreção fecal de N e/ou fibra em detergente ácido (FDA) no ensaio com azevém (R2 variou de 0,69 a 0,85) e com a excreção fecal de N, FDA ou fibra em detergente neutro (FDN) nos ensaios com Cynodon (R2 variou de 0,51 a 0,56). Conclui-se que a excreção fecal de FDA e/ou N tem um alto potencial para estimar consumo por animais em pastejo. A síntese de nitrogênio microbiano ruminal estimado pela metodologia das purinas duodenais ou dos derivados de purinas excretados na urina não foi similar (P<0,01). Adicionalmente, estas estimativas foram altamente influenciadas pela relação purinas:N microbiano utilizada nos cálculos.
11
Araújo, Helena Paula de Freitas Caldeira. "Purines, creatine, defective methylation and their biochemical and clinical relationship." Tese, Porto : Edição do Autor, 2003. http://catalogo.up.pt/F?func=find-b&local_base=UPB01&find_code=SYS&request=000115547.
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Liu, Yang Glaser Rainer. "Variable-temperature ¹H-NMR and AB initio study of 5-amino-imidazole-4-carboxamide (AICA) competing paths for amide-H scrambling /." Diss., Columbia, Mo. : University of Missouri--Columbia, 2008. http://hdl.handle.net/10355/6281.
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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb. 18, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dr. Rainer Glaser, Thesis Supervisor. Includes bibliographical references.
13
Pinson, Benoît. "Purification et caractérisations chimique et fonctionnelle de la purine-cytosine perméase de la membrane plasmique de la levure Saccharomyces cerevisae." Bordeaux 2, 1996. http://www.theses.fr/1996BOR28443.
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L'objectif de ce travail est l'étude biochimique et bioénergétique du mécanisme moléculaire de fonctionnement de la Purine-Cytosine Perméase (PCP), protéine intrinsèque de la membrane plasmique de la levure Saccharomyces cerevisiae qui catalyse l'entrée dans la cellule de trois bases purines (adenine, hypoxanthine et guanine) et de la cytosine. La PCP solubilisée par un détergent non ionique a pu être purifiée par chromatographie d'affinité, soit par une colonne de chélate de nickel en travaillant avec une forme modifiée de la protéine (six résidus histidyles ajoutés à son extrémité C-terminale), soit sur une colonne d'immunoaffinité construite avec un anticorps anti-C terminal, mais en travaillant cette fois-ci avec la forme sauvage du transporteur. Ces deux approches ont permis d'obtenir des échantillons de PCP pure à 90 %, et l'analyse de la séquence de la protéine purifiée nous a montré que cette protéine avait son extrémité N-terminal bloquée. L'immunoprécipitation de la PCP après des marquages in vivo des proréines cellulaires avec de l'ortophosphate radioactif a permis de mettre en évidence que la PCP est phosphorylée. Cette phosphorylation se produit sur des résidus séryles au cours du trafic des protéines entre l'appareil de Golgi et la membrane plasmique ou dans cette membrane elle même. La fusion (par congélation décongélation et extrusion) de préparations enrichies en membranes plasmiques de souches surexprimant la PCP et de protéoliposomes contenant la cytochrome c oxydase a permis d'obtenir des vésicules closes dans lesquelles nous avons pu générer une différence de potentiel électrochimique transmembranaire en protons. Ce système artificiel a permis de prouver que la PCP est un transporteur actif secondaire qui catalyse un symport proton/base et qui utilise principalement la composante chimique de la force proton-motriceThe aim of this work is the biochemical and bioenergetical analyses of the uptake mechanism of the Purine-Cytosine Permease (PCP), a protein located in the plasma membrane of the yeast Saccharomyces cerevisiae which catalyses adenine, guanine, hypoxantine and cytosine transport in cells. After solubilisation with a non ionic detergent, PCP was purified by affinity chromatography, either on nickel chelate affinity column using a recombinant PCP carrying a carboxy-terminal affinity tag for metallic ions (six successive histidyl residues), or on immunoaffinity column obtained with anti-C-terminal peptide) IgG using a wild-type PCP. By means of these two chromatographies, we have obtained a PCP enriched fraction containing 90 % of this protein. Determination of the PCP saquence shows a blocked N-terminal extremity. By means of in vivo radioactive ortophosphate labelling of cells proteins and PCP immunoprecipitation, we demonstrate that this protein is phosphorylated. This phosphorylation occurs on seryls residues in the secretory pathway either between the Golgi apparatus and the plasma membrane or in the plasma membrane itself. Plasma membrane enriched fractions containing PCP were fused with proteoliposomes containing cytochrome oxidase to obtain closed vesicles in which proton motive force could be generated and maintained. By means of this artificial system, we demonstrate that PCP is a secondary active carrier that catalyses a proton/base symport using mainly the chemical component of the proton motive force
14
Hartley, David John. "Thieniomidazoles, thieno-extended purines and related triazole systems." Thesis, University of Salford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299149.
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McKeveney, Declan, and n/a. "The Solid-Phase Combinatorial Synthesis of 2,6,9- Trisubstituted Purines as Potential Adenosine A3 Receptor Antagonists." Griffith University. School of Science, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050830.120105.
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Purines as a class of compounds have been implicated in many biological systems, including as adenosine receptor antagonists. A method of synthesising 2,6,9-trisubstituted purines would be useful to produce small libraries of compounds for probing adenosine receptor selectivity. A library of trisubstituted purines has been achieved using a solid-phase methodology. The electronic properties of the substrate were found to result in difficulties with the loading of substrate onto the resin. Theoretical calculations provided the basis for mono-substitution in order to activate the substrate. This modified substrate has loaded onto the resin in reproducible and high yields. Amine and thiol, on-resin, C-2 substitution was shown to proceed at room temperature. This represents significantly milder conditions than are generally seen in the literature. This is due to the activating effect of the carbamate linker chosen on the pyrimidine ring. This also results in a faster reaction rate than is seen in the corresponding solution-phase reaction. This study showed that the electronic profile of the loaded substrate was responsible for the low alkylation on the carbamate nitrogen of loaded dichloro- or C-6 substituted chloropyrimidines. This reaction was modified by activating the pyrimidine ring via C-2 substitution and has been shown to go to completion with three different alkyl groups to give a clean product direct from resin cleavage. On-resin nitro reduction had been planned. The resin bound product would then be carried on to the next step of resin cleavage and cyclisation of the imidazole ring to give the final purine products. On resin reduction could not be achieved, however, cleavage of the compound from the resin and reduction in solution was found to be efficient as the cyclisation reagents could be included in this step without interfering with yield or purity of products and so this represents a clear improvement upon the planned synthesis. Efforts to fully characterise the library brought up issues of purine NMR. Extremely broad signals were observed in the proton spectra of many of the compounds making assignments difficult. Broad 13C NMR signals have also been observed. Restricted rotation about the substituent N-C bond is responsible for these problems. Crystal structure data has confirmed the double bond character of this bond with one of the substituted pyrimidines. High temperature NMR experiments have demonstrated how this can be overcome and the fine structure of the spectra observed. HMBC and COSY correlations have been used alongside the 1H and 13C spectra to allow full characterisation of the compounds wherever possible. Receptor homology models were created and updated for all four adenosine receptor subtypes. Known adenosine agonists and antagonists were created and minimised for use in docking experiments. Receptor docking experimental data is reported. Binding assays are being carried out by a third party and will be submitted for publication at a later date. A small library of 2,6,9-trisubstituted purines has been synthesised, exemplifying an efficient and robust method to achieve pure compounds for biological evaluation. A good level of diversity has been achieved at each combinatorial position (two substitutions and an N-alkylation). Final compounds have been isolated in good yields with a high level of purity.
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McKeveney, Declan. "The Solid-Phase Combinatorial Synthesis of 2,6,9- Trisubstituted Purines as Potential Adenosine A3 Receptor Antagonists." Thesis, Griffith University, 2005. http://hdl.handle.net/10072/367926.
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Purines as a class of compounds have been implicated in many biological systems, including as adenosine receptor antagonists. A method of synthesising 2,6,9-trisubstituted purines would be useful to produce small libraries of compounds for probing adenosine receptor selectivity. A library of trisubstituted purines has been achieved using a solid-phase methodology. The electronic properties of the substrate were found to result in difficulties with the loading of substrate onto the resin. Theoretical calculations provided the basis for mono-substitution in order to activate the substrate. This modified substrate has loaded onto the resin in reproducible and high yields. Amine and thiol, on-resin, C-2 substitution was shown to proceed at room temperature. This represents significantly milder conditions than are generally seen in the literature. This is due to the activating effect of the carbamate linker chosen on the pyrimidine ring. This also results in a faster reaction rate than is seen in the corresponding solution-phase reaction. This study showed that the electronic profile of the loaded substrate was responsible for the low alkylation on the carbamate nitrogen of loaded dichloro- or C-6 substituted chloropyrimidines. This reaction was modified by activating the pyrimidine ring via C-2 substitution and has been shown to go to completion with three different alkyl groups to give a clean product direct from resin cleavage. On-resin nitro reduction had been planned. The resin bound product would then be carried on to the next step of resin cleavage and cyclisation of the imidazole ring to give the final purine products. On resin reduction could not be achieved, however, cleavage of the compound from the resin and reduction in solution was found to be efficient as the cyclisation reagents could be included in this step without interfering with yield or purity of products and so this represents a clear improvement upon the planned synthesis. Efforts to fully characterise the library brought up issues of purine NMR. Extremely broad signals were observed in the proton spectra of many of the compounds making assignments difficult. Broad 13C NMR signals have also been observed. Restricted rotation about the substituent N-C bond is responsible for these problems. Crystal structure data has confirmed the double bond character of this bond with one of the substituted pyrimidines. High temperature NMR experiments have demonstrated how this can be overcome and the fine structure of the spectra observed. HMBC and COSY correlations have been used alongside the 1H and 13C spectra to allow full characterisation of the compounds wherever possible. Receptor homology models were created and updated for all four adenosine receptor subtypes. Known adenosine agonists and antagonists were created and minimised for use in docking experiments. Receptor docking experimental data is reported. Binding assays are being carried out by a third party and will be submitted for publication at a later date. A small library of 2,6,9-trisubstituted purines has been synthesised, exemplifying an efficient and robust method to achieve pure compounds for biological evaluation. A good level of diversity has been achieved at each combinatorial position (two substitutions and an N-alkylation). Final compounds have been isolated in good yields with a high level of purity.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Science
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Duperray, Maëlle. "Rôle des gènes de la voie de biosynthèse des purines au cours du développement embryonnaire de Xenopus laevis." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0750/document.
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La voie de biosynthèse des purines est une voie métabolique conservée et essentielle. Chez l’Homme, des mutations dans plusieurs gènes impliqués dans cette voie provoquent de sévères maladies neuro-musculaires à composante développementale. Cependant, le lien entre génotypes et phénotypes n’est pas connu. Afin de mieux comprendre le rôle des gènes de la voie des purines au cours du développement, nous avons utilisé Xenopus laevis comme modèle vertébré. Les principaux gènes de la voie des purines du xénope n’étaient pas connus, ils ont donc tout d’abord été identifiés in sillico, puis les fonctions enzymatiques pour lesquels ils codent ont été validées in vivo en système hétérologue chez S. cerevisiae. Des analyses d’expression spatiotemporelle chez l’embryon de xénope ont montré que ces gènes sont exprimés tout au long du développement et en particulier dans les tissus neuro-musculaires, suggérant un rôle dans le développement de ces tissus. Le knock-down des gènes, ppat, hprt ou adsl, trois gènes clés de la voie des purines, conduit dans chaque cas à de sévères altérations des muscles squelettiques et en particulier des somites et des muscles hypaxiaux des embryons. Ces phénotypes musculaires sont la conséquence d’une altération précoce de l’expression des gènes MRF (Myogenic Regulatory Factors) myoD et myf5. Un défaut de migration des myoblastes précurseurs des muscles hypaxiaux a également été mis en évidence. Pour conclure, X. laevis est un modèle pertinent qui apporte de nouvelles connaissances permettant de mieux comprendre la cause des altérations musculaires développementales associées aux déficiences en purinesThe purine biosynthesis pathway is a conserved metabolic pathway essential for many cell functions. In Human, several mutations in genes involved in this pathway lead to severe neuromuscular diseases, which are at least in part caused by unknown developmental impairments. We established a Xenopus laevis model to decipher the role of the purine biosynthesis genes during vertebrate development. As no data was available regarding this pathway, the main Xenopus purine genes were first identified in silico and functionally validated in vivo using the yeast Saccharomyces cerevisiae as a heterologous system. Spatio-temporal analyses revealed that these genes are expressed all along the development, especially in neuromuscular tissues, suggesting an important role during their formation. The knock-down of ppat, adsl or hprt, three key purine genes, leads in each case to severe defects in skeletal muscles embryonic defects, in particular in somites and hypaxial muscles. These muscular phenotypes are the consequence of an early alteration in expression of some crucial Myogenic Regulatory Factors (MRF), such as myoD and myf5. Moreover, an alteration of the hypaxial muscles precursors was observed. In conclusion our results establish X. laevis as an ideal model to get new insights into the neuromuscular developmental alterations associated to purine deficiencies
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Marsac, Roxane. "La déficience en Adénylosuccinate Lyase - de la déficience métabolique aux défauts musculaires en utilisant le Caenorhabditis elegans comme modèle animal." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0321.
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La voie de biosynthèse des purines est un réseau métabolique conservé de procaryotes à l'Homme, assurant l'homéostasie de l'ATP et du GTP. Les purines peuvent être synthétisées de novo, réutilisées ou produites par interconversion de métabolites existants à l'aide de la voie dite de recyclage. De plus, les intermédiaires peuvent agir en tant que métabolites signals régulant l'expression génique. Cette voie est bien caractérisée chez des micro-organismes tels la levure ou la bactérie, mais peu de choses sont connues chez les métazoaires. Différentes maladies sont associées à des déficiences enzymatiques de la voie de biosynthèse des purines conduisant à des anomalies neuro-musculaires, des comportements du spectre autistique et à un retard psychomoteur chez l'Homme. Nous nous sommes particulièrement intéressés à la déficience en Adénylosuccinate Lyase (ADSL), une enzyme impliquée dans la voie de novo et dans la voie de recyclage des purines, responsable des symptômes neuronaux et musculaires chez les patients.Pour mieux comprendre les mécanismes sous-jacents à cette déficience, nous avons établi C. elegans comme organisme modèle métazoaire pour étudier la voie de la biosynthèse des purines, et en particulier le déficit en ADSL. Dans notre étude, par alignement de séquence, profil HPLC et complémentation fonctionnelle chez la levure, nous avons montré que la voie de novo et la voie de recyclage sont fonctionnellement conservées chez C. elegans. Grâce à notre étude, nous sommes en mesure d’attribuer des phénotypes développementaux et tissus spécifiques à des étapes séparables du métabolisme des purines dans un organisme modèle métazoaire. Notre analyse montre que l'activité ADSL dans la voie de recyclage joue un rôle crucial pour le maintien de la lignée germinale, pour l'intégrité musculaire et pendant le développement post-embryonnaireThe purine biosynthesis pathway is a metabolic network conserved from prokaryotes to humans, ensuring ATP and GTP homeostasis. Purines can either be synthesized de novo, reused, or produced by interconversion of extant metabolites using the so-called recycling pathway. Moreover, intermediates can act as signal metabolites regulating gene expression. This pathway is well characterized in microorganisms such as heat or bacteria, but little is know about its regulation in metazoans. Different diseases are associated with deficiencies in purine synthesis enzymes leading to neuromuscular defects, autistic spectrum behaviors and psychomotor delay in humans. We focused our analysis on the deficiency of Adenylosuccinate Lyase (ADSL), which is an enzyme involved in the purine de novo and the recycling pathways causing neuronal and muscular symptoms in patients. To better understand mechanisms underlying this deficiency, we have established C. elegans as a metazoan model organism to study the purine biosynthesis pathway, specially the ADSL deficiency. In our study, by sequence alignment, HPLC profiling and functional complementation in yeast, we have shown that both the de novo and the recycling pathway are functionally conserved in C. elegans. Thanks to our study, we are able to ascribe developmental and tissue specific phenotypes to separable steps of the purine metabolism network in a metazoan model organism. Our analysis shows that ADSL activity in the recycling pathway plays a crucial role for germline maintenance, for muscle integrity and during the post-embryonic development
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Lopatář, Ján. "Regulation of cortical excitability and seizure activity by purines." Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/46834/.
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The purine nucleoside adenosine is considered an important endogenous anticonvulsant, which exerts its actions via adenosine receptors. Adenosine can be released per se, or as ATP, which is then broken down to adenosine via the action of extracellularly located ectonucleotidases. ATP is a signalling molecule in its own right, which can activate ionotropic P2X and metabotropic P2Y receptors. While the role of adenosine and its receptors in epilepsy is well established, little data is known about the role of the P2 receptors. The aim of this work was threefold: (i) to what extent the P2 receptors modulate seizure-like activity in vitro, (ii) to detect the release of ATP and/or adenosine during seizure-like activity, and (iii) to establish the cellular source of the purines released. To do so, I used two NMDA receptor dependent models of electrically (high-frequency stimulation in Mg2+-free medium)- or chemically (6 mM K+ in Mg2+-free medium)- induced seizure-like events (SLE), and a model of bursting based on the activation of group I metabotropic glutamate receptors (GI mGluR). In my NMDA receptor-dependent models, I show that some P2 receptors partially aggravate SLEs, but their contribution is dwarfed compared to the powerful action of the adenosine A1 receptors. Accordingly, the minimal contribution of P2 receptors was reflected in my inability to detect ATP using microelectrode biosensors, despite my attempts to boost the amount of extracellular ATP using two ecto-ATPase inhibitors. GI mGluR-dependent bursting was partially blocked by the P2Y1 receptor antagonist MRS2179. Biosensor data revealed small, CA3 regionspecific ATP release. In contrast, larger quantities of adenosine were detected in all models used. Work with mice modified to express different levels of adenosine kinase (ADK) revealed that ADK plays an important role in regulating the amount of extracellular adenosine and seizure parameters. Furthermore, dn SNARE mice, in which astrocytic vesicular release of purines is selectively blocked, showed small amounts of SLE-related adenosine produced. My data suggest that P2 receptors partially contribute to seizure activity. Furthermore, I have confirmed the strong anticonvulsive action of adenosine, which is likely released from astrocytes, and tightly regulated by ADK. Thus, work contained in this thesis will hopefully contribute to the on-going attempts to establish adenosine-based epilepsy therapies.
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Obispo, Nestor E. "Feasibility of using total purines as a microbial marker /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487948440826443.
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Ibrahim, Nada. "Conception et synthèses régiospécifiques de purines di- et trisubstituées comme inhibiteurs de la glycogène synthase kinase-3." Paris 11, 2010. http://www.theses.fr/2010PA112006.
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La glycogène synthase (GSK-3) est une enzyme qui participe à une multitude de processus biologiques. Elle est notamment impliquée dans certaines maladies comme l’Alzheimer le le diabète de type 2. Dans ce contexte, la GSK-3 est devenue une cible privilégiée en chimie médicinale pour concevoir et découvrir des inhibiteurs sélectifs pouvant présenter un intérêt thérapeutique pour le traitement de ces maladies. Dans le but de continuer la recherche d’inhibiteurs présentant un meilleur profil de sélectivité, nous nous sommes proposés de synthétiser une « librairie » de nouveaux inhibiteurs de GSK-3, dérivés des purines, et mimant l’ATP, le ligand naturel de l’enzyme. Au cours de ce travail de thèse, nous avons mis au point différentes méthodes de synthèse de purine modifiées sur les atomes périphériques C2,C6,N7,C8 et N9 du noyau. Les méthodes de synthèse ainsi développées ont permis de construire une librairie de purines diversifiées possédant des applications biologiques potentielles. A présent 64 exemples de purines substituées comportant des substituant aryles en position C8, des substituants amides, amines, et éthers en position C6 ainsi que des purines comportant des groupements méthyles en position N7 ou N9 sont évalués en tant qu’inhibiteurs de glycogène synthase kinase-3 (GSK-3) et ont déjà fourni des résultats prometteurs. Les modes de liaisons des molécules actives ont été élucidés par docking dans le site actif de la GSK-3The purin core is privileged scaffold in medicinal chemistry which is frequently used in the preparation of combinatorial libraries. Its seven peripheral atoms may be considered as seven potential points of structural diversity. A wide variety of interesting inhibitors, such as kinases inhibitors, and modulators of key biological targets have been found among derivatives bearing various combinations of substituents at these centers. In the aim to discover new glycogen synthase kinase inhibitors which is an enzyme involved in many pathological processes such as type 2 diabete and Alzheimer desease, we developed regiospecific and efficient methods for the synthesis of 6,7,8, 6,8,9, 2 , 6 and 6,8-purines, via a copper and palladium catalyzed amidation reaction and SNaAr reaction to give access to polysubstituted purine library bearing aryl groups at C8 position, amines, ethers and amides groups at C6 and finally methyl at N7 or N9 positions. The molecules have provided promising redults as Glycogen synthase kinase inhibitors. In addition, the binding mode of the most active molecules were elucidated by docking in the active site of GSK-3
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Rosso, Lia. "A study of pituicytes in primary culture : morphological plasticity, taurine release and implications for oxytocin and vasopressin output." Nice, 2004. http://www.theses.fr/2004NICE4015.
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L’ocytocine et la vasopressine sont synthétisées et sécrétées par les neurones du système hypothalamo-neurohypophysaire. Les éléments non-neuronaux les plus abondants du lobe neural sont les pituicytes, des cellules gliales spécialisées, qui jouent un rôle important dans la modulation de la sécrétion des deux neurohormones. En effet, dans des situations physiologiques qui nécessitent une augmentation de la sécrétion d’ocytocine et de vasopressine, les pituicytes modifient leur morphologie. Ces changements morphologiques sont comparables à l’étoilement en culture primaire. De plus, les pituicytes peuvent moduler la sécrétion de vasopressine en libérant la taurine. Nous avons montré que l’ATP et l’adénosine induisent l’étoilement des pituicytes alors que les neurohormones induisent la réversion de l’étoilement. Ces deux phénomènes impliquent l’activation de différentes voies de signalisation. L’étape clé de l’étoilement est l’inhibition de la protéine Rhoa : la réversion de cet étoilement nécessite l’activation de CDC42. Les hormones induisent aussi une augmentation de la libération de taurine par les pituicytes par un mécanisme calcium-dépendant. En revanche, l’adénosine induit une diminution de la libération basale de taurine. Aussi bien la voie purinergique que la voie de signalisation activée par les neurohormones contrôle la morphologie des pituicytes et la libération de taurine par ces cellules. Nos résultats nous ont amené à proposer un modèle dans lequel, par le biais des pituicytes, la voie purinergique induirait une facilitation de la sécrétion hormonale alors que les neurohormones exerceraient un rétrocontrôle négatif de leur propre sécrétionOxytocin and vasopressin are synthesized and secreted by the neurons of the hypothalamo-neurohypophysial system. The most abundant non-neural elements of the neural lobe are the specialized glial cells pituicytes. These cells are a key element in the modulation of the secretion of both neurohormones. Indeed, under physiological conditions requiring a high output of hormones, pituicytes modify their own morphology. This phenomenon seems to correspond to the pituicytes stellation in primary culture. On the other hand, pituicytes may modulate the secretion of vasopressin by releasing taurine, which inhibit the secretion of vasopressin. In this study we have shown that ATP and adenosine induce stellation of pituicytes in primary culture while the neurohormones induce the reversal of stellation. The pathways involved in the two opposite phenomena are different. The key step of pituicytes stellation is inhibition of RHOA, while the reversal of stellation is mediated by the activation of CDC42. In this study we have also shown that oxytocin and vasopressin induce and increase adenosine decreases the basal taurine efflux from pituicytes. Thus, our results suggest that both purinergic and neurohormones pathways control the functions and activities of pituicytes by regulating both their morphology and also their capacity to release taurine. More particularly, from our results emerges the hypothesis that by modulating the activity of pituicytes the activation of the purinergic pathway facilitates neurohormone release, whereas the neurohormones exert a negative feed-back on their own secretion
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García, Sesnich Cristián Patricio. "Pequeños medios de generación distribuida: caso aplicación purines de cerdos." Tesis, Universidad de Chile, 2007. http://www.repositorio.uchile.cl/handle/2250/104756.
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Dalziel, Hugh H. "The role of purines in sympathetic neurotransmission in smooth muscles." Thesis, University of Glasgow, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278487.
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Araújo, Helena Paula de Freitas Caldeira. "Purines, creatine, defective methylation and their biochemical and clinical relationship." Doctoral thesis, Universidade da Madeira, 2003. http://hdl.handle.net/10400.13/226.
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Araújo, Margarida Duarte Cerqueira Martins de. "Endogenous purines as potential pharmacological targets to control myenteric neurotransmissions." Doctoral thesis, Instituto de Ciências Biomédicas Abel Salazar, 2010. http://hdl.handle.net/10216/57129.
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Araújo, Helena Paula de Freitas Caldeira. "Purines, creatine, defective methylation and their biochemical and clinical relationship." Doctoral thesis, Porto : Edição do Autor, 2003. http://hdl.handle.net/10216/64652.
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Geremia, Kara L. "Computational Estimation of the pKa's of Purines and Related Compounds." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1449754930.
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Dabouis, Vincent. "Pyrido[1,2-e]purines : structures, interactions membranaires et activités intercalantes." Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE19013.
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Hanna, Ramy Lewez. "Role played by purines in evoking the exercise pressor reflex /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Araújo, Margarida Duarte Cerqueira Martins de. "Endogenous purines as potential pharmacological targets to control myenteric neurotransmissions." Tese, Instituto de Ciências Biomédicas Abel Salazar, 2010. http://hdl.handle.net/10216/57129.
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Spiegel, Erin Kathleen. "Psychomotor deficits in mice transgenic for a mutant adenylosuccinate lyase associated with autism in humans /." Connect to full text via ProQuest. IP filtered, 2006.
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Thesis (Ph.D. in Human Medical Genetics) -- University of Colorado at Denver and Health Sciences Center, 2006.Typescript. Includes bibliographical references (leaves 127-143). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;
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Black, Duncan Arthur. "Aspects of purine and pyrimidine metabolism." Doctoral thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/26590.
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In Chapter 1 a review of the literature concerning aspects of erythrocyte membrane transport and metabolism, and purine and pyrimidine metabolism is presented. The effects of pH, pO₂ and inorganic phosphate (Pi) on the uptake and metabolism of hypoxanthine by erythrocytes has been studied in Chapter 2. Uptake of hypoxanthine and accumulation of inosine 5'-monophosphate (IMP) were markedly increased at acid pH, high external phosphate concentrations, and low pO₂. Release of accumulated IMP as hypoxanthine occurred at alkaline pH values and low external phosphate concentrations. Conditions favouring IMP accumulation gave rise, in the absence of hypoxanthine, to a corresponding increase in 5'-phosphoribosyl-1-pyrophosphate (PRPP). Intracellular phosphate concentrations were markedly pH dependent and a model is presented whereby hypoxanthine uptake and release are controlled by intracellular concentrations of inorganic phosphate and 2,3- bisphosphoglycerate (2,3-DPG). These allosteric effectors influence, in opposing ways, two enzymes governing IMP accumulation, namely PRPP synthetase and 5'-nucleotidase. These metabolic properties suggest that the erythrocyte could play a role in the removal of hypoxanthine from anoxic tissue. In Chapter 3 the kinetics and mechanism of transport of orotate across the human erythrocyte membrane and the effect of pH and inorganic phosphate on its metabolism (in the erythrocyte) have been studied. It has been shown that orotate enters erythrocytes with non-saturable kinetics and with a capacity of 190 μmoles/1 packed cells/min at a concentration of 4-6 mmolar. The presence of competition for transport by a number of anions and the lack of competition by uridine is indicative of transport by a general anion transporter, with the ability for concentrative uptake in the absence of other external anions being compatible with transport via a ping-pong mechanism. Inhibition of transport by the specific band 3 inhibitors DIDS and CHCA confirm that transport is via the band 3 anion transporter. This explains the lack of significant uptake of orotate by most differentiated tissues which lack the intact band 3 protein. However, the demonstration of band 3 in rat hepatocytes (Cheng and Levy, 1980) provides a mechanism for the orotate transport which has been observed in liver (Handschumacher and Coleridge, 1979). Changes in pH and inorganic phosphate (Pi) concentrations have been shown to have marked effects on the relative quantities of metabolic products produced by the erythrocyte from orotate. There was an increase in orotate metabolised with increasing Pi, an effect augmented by lowering the pH, and most easily explained by the allosteric activation of PRPP synthetase by Pi. The increase in UTP levels with decreasing pH may be the consequence of both increased PRPP availability for the formation of uridine nucleotide from orotate, and decreased conversion of UMP to uridine by pyrimidine 5'-nucleotidase, which is known to be inhibited by phosphate. The accumulation of UDP sugars is optimal at a phosphate concentration of 10 mmolar, which is unexplained but would be compatible with an inhibitory effect of Pi on CTP synthetase. A PRPP wasting cycle at alkaline pH values is proposed to explain the apparent paradox where no PRPP was observed to accumulate in erythrocytes (Chapter 2) at pH values of 7.6 and above in the presence of 10 mmolar phosphate and no added hypoxanthine, yet the metabolism of orotate, which is a PRPP utilising reaction, at alkaline pH values was readily demonstrable here. This (apparent paradox) can be resolved if one assumes that even in the absence of added hypoxanthine and demonstrable intracellular IMP there are sufficient quantities of hypoxanthine and/or IMP to maintain a PRPP wasting cycle at alkaline pH values. The cycle is interrupted at acidic pH values as phosphate levels rise and inhibit 5'-nucleotidase, an effect augmented by the decreasing levels of 2,3-DPG which accompany decreasing pH. This wasting cycle has recently been confirmed by P. Berman (unpublished). The kinetics of orotate uptake by erythrocytes and its eventual release as uridine provides a role for the erythrocyte in the transport and distribution of pyrimidines to peripheral tissues. A model is proposed and involves the de novo production of orotate in the liver. In the next step erythrocytes take up the orotate secreted by the liver into the circulation, convert it into an intermediate buffer store of uridine nucleotides, whose distribution is a function of pH and phosphate concentration, and eventually release it as uridine, which is a readily available form of pyrimidine for utilisation by peripheral nucleated cells. The enhancement of uptake of labelled orotate into nucleic acids of cultured cells is demonstrated here. The degradative half of the cycle proposes that uracil and palanine are the predominant degradative forms of pyrimidines produced by peripheral cells, and their ultimate metabolic fate is complete catabolism in the liver to CO₂ and water. In the final chapter the possible role of the human erythrocyte in the prevention of reperfusion injury has been investigated. The development of a model of renal ischaemia in the rat is described. The ability of human erythrocytes, "primed" by preincubating in acid medium of high Pi concentration and low pO₂, to take up hypoxanthine in a concentrative manner when perfused through ischaemic rat kidney is demonstrated. Attempts to demonstrate improved survival and renal function in rats with "primed" human erythrocytes prior to reperfusion were, however, unsuccessful. It is further demonstrated that "unprimed" human erythrocytes, resident in ischaemic rat kidney for 3 hours, take up hypoxanthine and convert it to IMP. that erythrocytes could play a physiological prevention of reperfusion injury.
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Sivendran, Sharmila. "Bacillus subtilis and human adenylosuccinate lyase I. Studies of two novel point mutations of ASL deficiency II. Effect of adjacent amino acids on the pK of His68 III. Studies with a new substrate analogue /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 147 p, 2008. http://proquest.umi.com/pqdweb?did=1456297461&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Lagos, Susaeta Francisco Manuel. "Análisis de factibilidad técnica y económica de la generación de biogás a partir de purines mediante biodigestores anaerobios." Tesis, Universidad de Chile, 2013. http://repositorio.uchile.cl/handle/2250/131621.
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Memoria para optar al Título Profesional de Médico VeterinarioLos sistemas productivos del mundo viven un desafío importante de sustentabilidad y giro hacia tecnologías más limpias. La digestión anaerobia es una tecnología que puede atenuar el impacto que producen los sistemas pecuarios en el medio, además de generar un nuevo recurso, el biogás, junto con otros beneficios ambientales, económicos y sociales. Por tales razones se desarrolló el presente trabajo, que tuvo por objetivo describir la situación actual del uso de purines para la generación de biogás mediante digestión anaeróbica, y generar modelos de biodigestores anaerobios aplicables a lecherías en Chile. En base a revisión bibliográfica y visita de experiencias, se recabaron aspectos teórico-prácticos de generación de purines lecheros; digestión anaerobia de purines con el biogás como principal producto; biodigestores anaerobios; y sobre proyectos de biodigestores anaerobios en lecherías chilenas y en un sistema de bovinos de engorda. La biodigestión anaerobia es un proceso bacteriano que logra rescatar cerca del 65% de la energía contenida en los purines, siempre que los parámetros sean manejados adecuadamente, especialmente la temperatura y el pH, además de limitantes como el sulfuro de hidrógeno, oxígeno, fibra y espuma. El principal producto de la digestión anaerobia es el biogás, el que tiene una constitución similar al gas natural. Comúnmente se establecen 4 tipos de biodigestores anaerobios: lagunas cubiertas, mezcla completa, flujo continuo y película fija. Para la elección del modelo de biodigestor se deben considerar los volúmenes de purín producidos, la cantidad de sólidos contenida y el volumen de biogás a generar. Además, los distintos modelos tienen distintas eficiencias y demandas externas de mezcla, temperatura, etc. En Chile existen alrededor de 6 plantas de biogás funcionando en base a purines, lo que denota una baja implementación nacional de estos sistemas, atribuido principalmente a: la falta de información en cuanto a los beneficios potenciales, escasos elementos de fomento, alta inversión requerida, dificultades técnicas y falta de profesionales especialistas. En base a recopilación bibliográfica y entrevistas a profesionales, se identificaron posibles beneficiarios de sistemas de digestión anaerobia de purines en relación a los volúmenes y capacidad energética de los purines producidos, y tecnologías posibles de implementar gracias a la generación del biogás, usado como sustrato energético para las lecherías. Mediante la combustión del biogás es posible generar calor, frio, energía mecánica y electricidad. La industria lechera presenta un gran potencial en este aspecto, ya que por la energía contenida y los grandes volúmenes de purines producidos, se puede suplir hasta el 100% de requerimientos energéticos como la ordeña mecánica 2 y la refrigeración de la leche. El producto más interesante del biogás es la electricidad, para la cual es necesario analizar la factibilidad de generación dadas las posibilidades de inversión, y los volúmenes de purín generados. Toda la información y experiencia sirvió como sustrato para la generación de dos modelos teóricos de biodigestores anaerobios para lecherías en Chile; uno para pequeñas lecherías y otro para lecherías de tamaño mediano, especificando sus características y requerimientos, así como los modelos de biodigestores a usar, productos generados e inversión aproximada
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Cultrone, Antonietta. "La xanthine dioxygénase α-kétoglutarate dépendante : une enzyme caractéristique des champignons." Paris 11, 2004. http://www.theses.fr/2004PA112069.
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Le sujet de cette thèse est le clonage du gène xanA et le caractérisation de la protéine XanA d'Aspergillus nidulans. XanA est une enzyme qui hydroxyle la xanthine en acide urique. Dans une souche sauvage la purine hydroxylase I (HxA) catalyse l'hydroxylation de l'hypoxanthine en xanthine et de la xanthine en acide urique. L'hypoxanthine peut aussi être hydroxylée par la purine hydroxylase II codée par le gène hxnS. Les purines hydroxylases I et II sont des enzymes associées à un cofacteur à molybdène, alors que XanA ne l'est pas. Nous avons cloné et séquencé le gène xanA. Il code une protéine de 370 acides aminés. XanA présente des similarités avec les protéines de la famille des dioxygénases. Des protéines fortement similaires à XanA n'ont été trouvées que chez les champignons (N. Crassa, S. Pombe, F. Graminearum, P. Chrysosporium, C. Cinereus, U. Maydis, C. Albicans). Une mutation dans le gène xanA a été isolée. Cette mutation (xanA1) est une transversion de C à A qui se traduit par le remplacement d'une alanine par une asparagine au niveau du codon 167. Le phénotype de la délétion du gène xanA est identique à celui de xanA1. La surexpression de xanA chez A. Nidulans a permis de caractériser l'enzyme. Nous avons démontré qu'il s'agit d'une xanthine dioxygénase dépendante de l'a-kétoglutarate. Le gène xanA (chromosome VIII) et son promoteur sont partiellement dupliqués sur le chromosome II. L'homologue de xanA chez S. Pombe (TC3962) ne complémente pas la mutation xanA1 d'A. Nidulans, tandis que cette mutation est complementée par l'homologue de xanA chez N. Crassa (xan1). L'expression de xanA est soumise au contrôle du facteur GATA AreA et est dépendante du facteur UaYThis work comprises the cloning of the xanA gene and the biochemical characterization of the XanA protein of aspergillus nidulans. This enzyme catalyses the oxidation of xanthine to uric acid. In the wild type strain, purine hydroxylase I (HxA) catalyses both the hydroxylation of hypoxanthine to xanthine and that of xanthine to uric acid. Hypoxanthine is also oxidized to xanthine by a second purine hydroxylase (purine hydroxylase II), which is coded by the hxnS gene. Both purine hydroxylases contain a molybdopterin co-factor while XanA does not. We have cloned and sequenced the xanA gene. XanA encodes a protein 370 amino acids long. The sequence of XanA has confirmed that it's not a molybdenum-containing enzyme; we found some similarities with proteins of the dioxygenase family. Proteins with high similarity to XanA were found only in fungi in N. Crassa, S. Pombe, F. Graminearum, p: chrysosporium, C. Cinereus, U. Maydis, C. Albicans. One mutation (xanA1) has been isolated. The xanA1 allele is a C to A transversion resulting in an alanine to asparagine change in codon 167. The phenotype of the xanA1 mutation is identical to that of xanA deletion. Overexpression of the xanAgene in A. Nidulans has permitted a preliminary characterization of the enzyme. We have shown it is an a-ketoglutarate dependent xanthine dioxygenase. The xanA gene (chromosome VIII), including its promoter is partially duplicated in chromosome II. The S. Pombe homologue of xanA, TC3962, is not able to complement the mutation xanA1. As all other enzymes of the purine utilization pathway xanA expression is under the control of the GATA factor AreA and the pathway specific transcription factor UaY
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Vita, Marina. "Preclinical studies of roscovitine /." Stockholm : Karolinska institutet, 2005. http://diss.kib.ki.se/2005/91-7140-302-7/.
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Retamoso, Leandro Thies. "PAPEL DO SISTEMA PURINÉRGICO E DOS RECEPTORES DE POTENCIAL TRANSITÓRIO VANILOIDE 1 (TRPV 1) NA DOR MUSCULAR TARDIA APÓS EXERCÍCIO EXCÊNTRICO EM RATOS." Universidade Federal de Santa Maria, 2014. http://repositorio.ufsm.br/handle/1/6715.
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Chronic exercise has been recommended as a strategy for preventing several diseases associated with lifestyle such as heart disease, hypertension, osteoporosis and type II diabetes. Although regular physical exercise has benefits for health, all sports practitioners, and even sedentary people, have already feel delayed onset muscle soreness (DOMS) once, characterized by discomfort in skeletal muscle. As the most DOMS generator, acute eccentric exercise induce fatigue, strength reduction and performance impairment. Despite some researches demonstrating reactive oxygen species (ROS) in this context, there are few information about purine degradation as well as transient receptor potential vanilloid 1 (TRPV1) on DOMS development. In this context, animals performed a downhill running test (eccentric exercise) on treadmill until exhaustion for histologic evaluation, mechanical allodynea, strength force test and biochemical analysis. The results showed an increase in mechanical allodynea and ADP, AMP, uric acid and TRPV1 immunoreactivity levels. In conclusion, the results support the contribution of ROS and the participation of purine and TRPV1 on delayed onset muscle soreness.O exercício físico crônico tem sido recomendado como estratégia para a prevenção de diversas doenças associadas ao estilo de vida, como doenças cardíacas, hipertensão, osteoporose e diabetes tipo 2. Embora o exercício físico regular traga benefícios para a saúde, todos os praticantes de atividade física e esporte e, até mesmo indivíduos sedentários, já experimentaram alguma vez na vida um episódio de dor muscular tardia (DMT), caracterizada pela sensação de desconforto na musculatura esquelética. Como grande gerador de DMT, destaca-se o exercício excêntrico agudo que induz fadiga, redução de força e perda de desempenho. Apesar de diversos estudos demonstrando a participação das espécies reativas de oxigênio neste quadro, pouco se sabe sobre a participação da degradação das purinas bem como a participação dos receptores de potencial transitório vaniloide 1 (TRPV1) no desenvolvimento da dor muscular tardia. Para tanto, os ratos wistar machos realizaram teste de downhill em esteira (exercício excêntrico) até a exaustão. Após foram analisados os danos histológicos nos músculos gastrocnêmio e sóleo, Outro set de animais após a exaustão foram avaliados nos testes de alodinea mecanica na pata traseira direita, teste funcional de força nas pastas dianteiras e análises bioquímicas no músculo gastrocnêmio. Os resultados demonstram aumento na alodinea, na carbonilação protéica, nos níves de ADP, AMP, ácido úrico, além de elevar os níveis de immureatividade do receptor TRPV1 e atividade da xantina oxidase. Esses dados apontam uma possível contribuição das espécies reativas de oxigênio, da degradação de purinas e dos receptores TRPV1 na dor muscular tardia.
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Rico, Eduardo Pacheco. "A utilização do zebrafish como modelo para avaliar a influência da exposição crônica ao etanol nos sistemas glutamatérgico, purinérgico e níveis de BDNF." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/31701.
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O zebrafish (Danio rerio) é uma espécie utilizada como modelo experimental em diversas áreas, tais como neurociências toxicologia. Seu genoma já está praticamente sequenciado e estudos demonstraram que muitos genes deste peixe são similares aos de mamíferos. Além disso, o zebrafish é um excelente modelo para estudar a função de diferentes sistemas de neurotransmissão. O consumo do etanol exerce diversas mudanças na coordenação motora, percepção sensorial e cognição promovendo um amplo espectro de alterações bioquímicas e fisiológicas nas células nervosas. Aqui, nós investigamos o efeito promovido pela exposição crônica de etanol nos sistemas purinérgico e glutamatérgico, e níveis de BDNF no SNC de zebrafish. Os transportadores de alta afinidade de aminoácidos (EAAT) regulam os níveis extracelulares de glutamato. Nós identificamos e descrevemos o padrão de expressão dos genes relacionados aos transportadores e as propriedades de captação de glutamato nas três importantes estruturas cerebrais de zebrafish (telencéfalo, tecto óptico e cerebelo). As pesquisas nos bancos de dados do seu genoma através de análise filogenética confirmaram a presença de diversos EAATs (EAAT2, EAAT3, três EAAT1 parálogos e duas sequências parálogas para EAAT5). Também, a captação de glutamato dependente de sódio foi significativamente maior no tecto óptico, indicando diferenças funcionais entre as estruturas cerebrais. Os EAATs pertencem à família dos carreadores de soluto 1 (SLC1), que constitui os transportadores de alta afinidade de aminoácidos e transportadores de aminoácidos neutros. Recentemente, foi demonstrada uma análise filogenética e clonagem dos genes SLC1/EAAT identificando distintos membros desta família de transportadores. No sentido de unificar a designação dos genes SLC1/EAAT em zebrafish, foi proposta uma nomenclatura comum para estes grupos. O etanol promoveu uma diminuição significativa na captação de glutamato após 7 e 14 dias de exposição (30% e 54%, respectivamente), enquanto que após 28 dias, não foram observadas alterações. Na,K-ATPase, a enzima responsável pelo controle do gradiente iônico, não teve sua atividade alterada após todos os períodos de exposição testados. Além disso, os peixes expostos ao etanol durante 7 e 14 dias tiveram uma redução nos níveis de mRNA para SLC1A1/EAAT3. Entretanto, a expressão gênica do SLC1A8a,b/EAAT6a,b aumentou após todos os períodos testados, enquanto que SLC1A3a,b/EAAT1b aumentou somente após 28 dias. A prolongada exposição ao etanol não foi capaz de alterar as atividades da glutamina sintetase e glutaminase. Da mesma forma, etanol não alterou a hidrólise de ATP e GTP. Entretanto, foi verificada uma diminuição na hidrólise de ADP (46% e 34%) e GDP (48% e 36%) após 7 e 14 dias respectivamente. Após 7 e 14 dias de exposição ao etanol, também foi observada uma significativa alteração na hidrólise de AMP (48% e 36%), enquanto que a hidrólise de GTP foi inibida somente após 7 dias (46%). Os níveis de transcritos das nucleosídeo trifosfato difosfohidrolase (NTPDases) foram alteradas após 7, 14 e 28 dias. Em contraste, a expressão da 5′-nucleotidase não foi alterada. A atividade da adenosina deaminase (ADA) na fração solúvel não foi modificada, mas uma redução da atividade na fração de membrana após 28 dias de exposição ao etanol (44%) foi observada. A análise da expressão gênica demonstrou que ADA1 permaneceu inalterada, enquanto que os transcritos de ADAL, ADA2-2, ADA2-1, e sua isoforma truncada de ―splicing‖ alternativo (ADA2-1/T) foram alteradas após a ação prolongada do etanol. Após 14 e 28 dias, etanol aumentou a expressão gênica do BDNF, mas não alterou os níveis de transcritos para trkB. A determinação da proteína BDNF através dos métodos de ELISA indicou um aumento de (51%), sendo confirmando imunohistioquímicamente. Estes resultados sugerem que a homeostase da função neurotrófica pode ser alterada pelo prolongado consumo de etanol. Esta tembém inclui uma revisão sobre o papel de diferentes neurotransmissores excitatórios e inibitórios em zebrafish, tais como, dopaminérgico, serotoninérgico, colinérgico, glutamatérgico, purinérgico, histaminérgico, nitrérgico, glicinérgico, gabaérgico, enfatizando aspectos farmacológicos e toxicológicos. Em suma, esta tese demonstra o efeito da exposição crônica ao etanol afeta o sistema glutamtérgico e purinérgico, expressão de BDNF em cérebro de zebrafish. O aumento do conhecimento global sobre os sistemas de neurotransmisão em zebrafish e o esclarecimento de efeitos farmacológicos e toxicológicos poderia contribuir para novas estratégias de pesquisa em ciências básicas e biomédicas.The zebrafish (Danio rerio) is a species used as experimental models in various fields such as neurosciences, toxicology. Its genome has already been sequenced and studies have shown that many genes are similar to those of mammals. Furthermore, zebrafish provides an excellent model to study the function of different neurotransmitter systems. The ethanol consumption exerts several changes in motor coordination, sensory perception and cognition, promoting a wide-spectrum of biochemical and physiological alterations on nervous cells. Here we investigated the effects promoted by chronic ethanol exposure on glutamatergic and purinergic systems, and BDNF levels in zebrafish CNS. High-affinity excitatory amino acid transporters (EAATs) regulate extracellular glutamate levels. We identified and described the expression profile of EAATs-related genes and the functional properties of glutamate uptake in three major brain structures from zebrafish (telencephalon, optic tectum and cerebellum). Searches on zebrafish genome databases and a phylogenetic analysis confirmed the presence of several EAAT-related genes (EAAT2, EAAT3, three EAAT1 paralogs and two EAAT5 sequences). Moreover, the glutamate uptake was significantly higher in optic tectum, which indicates functional differences within zebrafish brain structures. EAATs belong to the solute carrier family 1 (SLC1), that constitute high-affinity glutamate and neutral amino acid transporters. Recently, the phylogenetic analysis and cloning reporting of SLC1/EAAT genes from zebrafish identified distinct members of this transporter family. In order to unify the nomenclature of SLC1/EAAT genes in zebrafish, it was proposed a common nomenclature for these groups. The actions of ethanol on glutamate uptake showed a significant decrease in glutamate transport (30% and 54%) after 7 and 14 days of exposure, whereas after 28 days, no significant changes were detected. Na,K-ATPase, the enzyme responsible to generate ion gradients, did not alter after all exposure periods. Moreover, fish exposed to ethanol during 7 and 14 days exhibit a decrease of mRNA levels for SLC1A1/EAAT3. However, the gene expression of SLC1A8a,b/EAAT6a,b increased after all exposure periods, whereas SLC1A3a,b/EAAT1b increased only after 28 days. The prolonged ethanol exposure did not significantly change the glutamine synthetase and glutaminase activities. In the same way, ethanol did not alter the ATP and GTP hydrolysis. However, a decrease in ADP (46% and 34%) and GDP (48% and 36%) hydrolysis was verified after 7 and 14 days, respectively. After 7 and 14 days of ethanol exposure, a significant decrease in AMP hydrolysis (48% and 36%) was also observed, whereas GMP hydrolysis was inhibited only after 7 days (46%). Furthermore, nucleoside triphosphate diphosphohydrolase (NTPDase) transcript levels were altered after 7, 14, and 28 days. In contrast, 5′-nucleotidase expression was not altered. Adenosine deaminase (ADA) activity from soluble fraction was not modified, but a decrease of ADA activity in membrane fraction after 28 days (44%) of ethanol exposure was observed. Gene expression analysis demonstrated that ADA1 remained unaltered, whereas ADAL, ADA2-2, ADA2-1 transcripts, and its truncated alternative splice isoform (ADA2-1/T) were altered after prolonged ethanol exposure. After 14 and 28 days, ethanol increased the BDNF gene expression, but did not change the levels of trkB transcripts. The measurement of BDNF protein through ELISA kit anti-BDNF showed increased amounts after 28 days of exposure (51%), which was also confirmed by immunohistochemstry. These results suggest that the homeostasis of neurotrophic functions may be altered by prolonged ethanol consumption. Moreover, we present a review about the role of different excitatory and inhibitory neurotransmitters systems in zebrafish, such as dopaminergic, serotoninergic, cholinergic, glutamatergic, purinergic, histaminergic, nitrergic, glycinergic, and GABAergic systems, emphasizing pharmacological and toxicological aspects. In conclusion, this thesis demonstrates that chronic ethanol exposure affects the glutamatergic and purinergic systems, and BDNF expression in zebrafish brain. The significant increase in the global knowledge about the neurotransmitters systems in zebrafish and the elucidation of pharmacological and toxicological effects could lead to new strategies and appropriate priorities in research in order to support complementary insights on basic sciences and biomedical research.
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Stefanello, Cristiano Miguel. "Avaliação de marcadores internos para estimativa de fluxo de digesta e proteína microbiana no duodeno de ruminantes." Universidade Federal de Santa Maria, 2014. http://repositorio.ufsm.br/handle/1/10849.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThe aim of this study was to evaluate the use of internal markers to estimate duodenal flow of digesta and duodenal microbial protein synthesis in cattle and sheep. Data and samples of in vivo digestibility trials, eight trials with sheep (n=204) and two with cattle (n=31) were used. All animals were cannulated in the duodenum, procedure previously conducted at the Laboratory of Food Science and Ruminants Nutrition at the Federal University of Santa Maria and Laboratory of Animal Nutrition and Food Science at the University of the State of Santa Catarina. Internal markers, acid detergent fiber (ADF) and acid detergent lignin (ADL) were compared to estimate the flow of duodenal digesta. Purines in duodenal digesta were compared with purine derivatives (PD) excreted in urine as markers to estimate the flow of rumen microbial protein in the duodenum. In the latter case, different equations available in literature were tested to estimate the flow of microbial protein from urinary PD. It was concluded that ADF may be used as an internal marker to estimate duodenal flow of digesta in experimental animals cannulated in the duodenum where total fecal excretion is measured, and that the use of DP as a marker of duodenal flow of microbial protein is acceptable for cattle but not for sheep. In sheep, regardless of the equation used, the DP underestimated duodenal availability of rumen microbial protein.
O objetivo do presente estudo foi avaliar o uso de marcadores internos para estimativa de fluxo de digesta duodenal e de síntese de proteína microbiana duodenal em bovinos e ovinos. Foram utilizados dados e amostras de oito ensaios de digestibilidade in vivo com ovinos (n=204) e dois com bovinos (n=31), canulados no duodeno, previamente conduzidos no Laboratório de Bromatologia e Nutrição de Ruminantes da Universidade Federal de Santa Maria e no Laboratório de Nutrição Animal e Bromatologia da Universidade do Estado de Santa Catarina. Para estimativa do fluxo de digesta duodenal, foram comparados os seguintes marcadores internos: fibra em detergente ácido (FDA) e lignina em detergente ácido (LDA). Para estimar o fluxo de proteína microbiana ruminal no duodeno, foi comparado o uso de purinas na digesta duodenal com os derivados de purinas (DP) excretados na urina como marcadores. Neste último caso, foram testadas diferentes equações disponíveis na literatura para estimar o fluxo de proteína microbiana a partir dos DP urinários. Concluiu-se que a FDA pode ser utilizada como marcador interno para estimar o fluxo duodenal de digesta em ensaios com animais canulados no duodeno, onde é medida a excreção total de fezes, e que o uso dos DP como marcadores do fluxo duodenal de proteína microbiana é aceitável em bovinos, mas não em ovinos. Em ovinos, independentemente da equação utilizada, os DP subestimam a disponibilidade duodenal de proteína microbiana ruminal.
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Sahnoun, Sophian. "C-H fonctionnalisation de purines : synthèse d'inhibiteurs potentiels de la HSP90." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00692582.
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Les résistances aux traitements actuels contre le cancer incitent à trouver de nouvelles cibles thérapeutiques. Une de ces cibles, la hsp90 (heat shock protein 90), impliquée dans la maturation de protéines clientes oncogènes, se révèle très prometteuse car son inhibition induit la dégradation de ces protéines par la voie du protéasome.PU3 et PU24S sont des inhibiteurs de la hsp90 de type purine fonctionnalisés en position 8. Dans le but d'identifier des composés encore plus actifs et/ou de nouvelles familles d'inhibiteurs, nous avons développé de nouveaux procédés sélectifs métallo-catalysés permettant l'activation de liaisons C-H de divers hétérocycles, et en particulier des purines (adénines, xanthines). Ces nouvelles approches ont permis un accès direct et simple à de nombreuses purines fonctionnalisées en C-8 par des groupements aromatiques, hetéroaromatiques, éthyléniques et benzyliques.
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Burch, L. R. "Properties of enzymes acting on cytokinins and other purines in plants." Thesis, University of Aberdeen, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356795.
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Sahnoun, Sophian. "C-H fonctionnalisation de purines : synthèse d’inhibiteurs potentiels de la HSP90." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA114803/document.
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Les résistances aux traitements actuels contre le cancer incitent à trouver de nouvelles cibles thérapeutiques. Une de ces cibles, la hsp90 (heat shock protein 90), impliquée dans la maturation de protéines clientes oncogènes, se révèle très prometteuse car son inhibition induit la dégradation de ces protéines par la voie du protéasome.PU3 et PU24S sont des inhibiteurs de la hsp90 de type purine fonctionnalisés en position 8. Dans le but d’identifier des composés encore plus actifs et/ou de nouvelles familles d’inhibiteurs, nous avons développé de nouveaux procédés sélectifs métallo-catalysés permettant l’activation de liaisons C-H de divers hétérocycles, et en particulier des purines (adénines, xanthines). Ces nouvelles approches ont permis un accès direct et simple à de nombreuses purines fonctionnalisées en C-8 par des groupements aromatiques, hetéroaromatiques, éthyléniques et benzyliquesResistance to current treatments of cancer encourages finding new therapeutical targets. The heat shock protein 90 (hsp90) is a molecular chaperon which regulates the folding of many client proteins associated with all of the six hallmarks of cancer, and helps maintaining their proper conformation. Consequently, the hsp90 has become an exciting new target in cancer drug discovery since the inhibition of its ATPase activity leads to depletion of these client proteins via the proteasomal pathway. PU3 and PU24S are purine-based hsp90 inhibitors functionalized on C-8 position. In the aim to identify more active compounds and/or new subfamilies of inhibitors, we have developed new metal-catalyzed C-H activation processes of various heterocycles including purines and other azoles. These new and simple approaches have allowed the access to numerous C-8 functionalized purines bearing (het)aryl, alkenyl and benzyl moieties
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Kulikov, Vladislav [Verfasser], Gerd [Akademischer Betreuer] Meyer, Leroy [Akademischer Betreuer] Cronin, Bernhard [Akademischer Betreuer] Lippert, and Hans-Günther [Akademischer Betreuer] Schmalz. "Hybrid Materials Consisting of Silver(I) Purine Complexes, Protonated Purines and Polyoxometalates / Vladislav Kulikov. Gutachter: Gerd Meyer ; Leroy Cronin ; Bernhard Lippert ; Hans-Günther Schmalz." Köln : Universitäts- und Stadtbibliothek Köln, 2013. http://d-nb.info/1044679964/34.
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Pelletier, Alexandrine. "Origine, métabolisme et effets des nucléotides et nucléosides extracellulaires sur le système circulatoire du cobaye." Sherbrooke : Université de Sherbrooke, 1999.
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Damaj, Mohamad Imad. "Évaluation pharmacocinétique et neurochimique chez l'animal d'un nouvel antidépresseur, le COR3224." Paris 11, 1991. http://www.theses.fr/1991PA114811.
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Deharvengt, Sophie. "Etude du système gène suicide/prodrogue : Purine nucléoside phosphorylase/6-méthyle purine désoxyribose et de son ciblage thérapeutique dans les carcinomes pancréatiques." Université Louis Pasteur (Strasbourg) (1971-2008), 2003. http://www.theses.fr/2003STR13209.
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Le cancer du pancréas reste une maladie peu ou pas curable, nécessitant le développement de nouveaux moyens thérapeutiques, tel que la thérapie génique. Une approche prometteuse est l'utilisation de systèmes gène suicide/prodrogue, consistant à insérer dans les cellules tumorales un gène codant pour une enzyme exogène capable de convertir une prodrogue, relativement non toxique, en un métabolite cytotoxique. Son avantage majeur est son effet de voisinage (bystander), qui permet une éradication de la tumeur sans que la totalité des cellules exprime le gène suicide, surmontant ainsi le faible taux de transfection rencontré dans les expériences in vivo. L'objectif de ce travail est d'étudier un nouveau système gène suicide/prodrogue : la Purine Nucléoside Phosphorylase d'Escherichia Coli (ePNP)/6-méthyle-purine désoxyribose (MePdR) dans le traitement des adénocarcinomes pancréatiques. EPNP converti le MePdR non toxique en un métabolite toxique, le 6-méthyle-purine (MeP). Le MeP est capable de tuer les cellules quiescentes, ce qui le distingue de la plupart des agents anti-tumoraux et permet son utilisation dans le traitement de tumeurs solides. Après clonage du gène et établissement de clones stables, la toxicité et l'effet bystander de ce système ont été vérifiés in vitro sur des modèles digestifs et in vivo sur des xénogreffes humaines chez des souris immunodéficientes. Le transfert d'ePNP par électropration a été évalué sur le même modèle de tumeurs localisées en sous cutané. Afin de mieux cibler l'expression d'ePNP dans les cellules tumorales, des promoteurs de marqueurs tumoraux ont été utilisés. Ils permettent l'expression sélective d'ePNP dans les cellules néoplasiques exprimant ces marqueurs. Enfin, pour prendre en compte le contexte clinique avec présence de métastases dans lequel l'électroporation s'avère difficilement applicable, une technique de transfert systémique par l'utilisation de parvovirus murins présentant des propriétés d'oncotropisme, a été utilisée. Tous les résultats obtenus mettent l'accent sur les potentialités du système ePNP/MePdR dans le traitement des adénocarcinomes pancréatiques humainsPancreatic cancer is a disease poorly or not curable that requires the development of new therapeutic tools, such as the gene therapy. A promising approach is the use of suicide gene/prodrug systems, which consists in transducing in the tumoral cells a gene encoding for an exogenous enzyme able to convert a prodrug, relatively safe, in a cytotoxic metabolite. The major advantage of this approach is its bystander effect (on the vicinity), which allows tumour eradication even when all cells are not expressing the suicide gene. It offers the opportunity to overcome the poor experimental rate of transfection encountered in vivo. The objective of the current work is to study a new suicide gene /prodrug system, Escherichia Coli Purine Nucleoside Phosphorylase (ePNP)/6-methylpurine deoxyribose (MePdR) for pancreatic adenocarcinoma treatment. EPNP converted non-toxic MePdR into a toxic metabolite 6-methyl-purine (MeP). The ability of MeP to kill the quiescent cells, on the contrary of the majority of the antitumour agents, allows its use for the treatment of solid tumours. After gene cloning and establishment of stable clones, toxicity and bystander effect of this system were checked in vitro on digestive models and in vivo on human subcutaneous tumour xenografts in immunocompromised mice. Transfer of ePNP gene by electroporation was evaluated on the same tumour model. We used promoters of tumour markers to improve the targeting of ePNP expression within tumour cells. They allow the selective expression of ePNP into the neoplastic cells expressing such markers. Lastly, taking in account a clinical situation with presence of metastases in which electroporation cannot be easily applied, we used murine parvovirus with oncotropic properties to perform a systemic transfer. Thus, all these results highlight the potentialities of the MePdR/ePNP system to treat human pancreatic adenocarcinoma
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BEGHOUL, FARIDA. "Nouveaux analogues des purines dans le traitement de la leucemie a tricholeucocytes." Strasbourg 1, 1995. http://www.theses.fr/1995STR15056.
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Quashie, Neils Benjamin. "Purine transport in plasmodium falciparum." Thesis, Thesis restricted. Connect to e-thesis to view abstract, 2008. http://theses.gla.ac.uk/165/.
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Thesis (Ph.D.) -- University of Glasgow, 2008.Ph.D. thesis submitted to the Division of Infection and Immunity, Institute of Biomedical and Life Sciences, University of Glasgow, 2008. Includes bibliographical references. Print version also available.
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Terrazas, Martínez Montserrat. "Marcatge amb 15N de purines i disseny de nous inhibidors del VIH-I." Doctoral thesis, Universitat de Barcelona, 2006. http://hdl.handle.net/10803/2797.
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En la present Tesi s'han intentat desenvolupar noves metodologies que permetin modificar les nucleobases puríniques dels nucleòsids amb dues intencions clarament diferenciades: d'una banda, el seu marcatge amb 15N, per tal de facilitar l'anàlisi estructural d'àcids nucleics; d'altra banda, la cerca de noves espècies antivíriques.En els capítols 1 i 2 d'aquesta memòria s'ha estudiat la reactivitat d'una àmplia gamma d'1-sulfonilinosines amb amines. L'objectiu final era comprovar si aquests substrats podrien experimentar atacs nucleòfils sobre la posició electròfila C2 per espècies com amines per a generar un intermedi obert, la posterior ciclació del qual hauria de portar a inosines modifiades en el N1. De les diferents vies de sulfonilació assajades (N1-tosil, N1-triisopropilbenzensulfonil, N1-pentafluorobenzensulfonil, N1-4- nitrobenzensulfonil, N1-2,4-dinitrobenzensulfonil, N1-2-nitrobenzensulfonil, N1-mesil i N1-triflil), la que va donar millors resultats en la reacció amb amoníac marcat fou la corresponent al grup 2-nitrobenzensulfonil. D'aquesta manera s'arribà amb bon rendiment a 2'-desoxiinosines totalment marcades en el N1. D'altra banda, en la reacció amb alquilamines, els grups 2-nitrobenzensulfonil i 2,4-dinitrobenzensulfonil van ser els candidats més adients per alquilar la posició N1 de l'anell de purina. D'aquesta manera es creà també una nova ruta d'accés cap a les 1-alquil-2'-desoxiinosines.
En el tercer capítol es presenta i es dicuteix un nou mecanisme de transposició de nucleobases puríniques que permet transformar directament inosines en adenosines N1-alquilades i en [1-15N]adenosines a partir de 2,4-dinitrobenzensulfonilinosines.
En el capítol 4 hem desenvolupat un nou mètode de marcatge amb 15N dels grups amino exocíclics de purines. La nostra idea inicial d'introduir directament 15NH3 sobre espècies puríniques activades de forma suau no ha estat possible. En canvi, l'acoblament catalitzat per Pd(0) de 6-bromopurines i 2-bromoinosiens amb quantitats estequiomètriques de [15N]benzamida va resultar molt efectiu. A més, aquest protocol, juntament amb el desenvolupat per al marcatge del N1 de 2'-desoxiinosines, ens ha permès descriure una nova ruta d'accés a les [N,1-15N2]adenosines.
Finalment, hem aplicat els procediments desenvolupats per a la modificació de nucleobases puríniques a la preparació de noves espècies nucleosídiques dimèriques dirigides a la inhibició de l'enzim transcriptasa inversa (RT) del virus de la immunodeficiència humana (VIH-1). Així, en el cinquè capítol ens hem centrat en el disseny, la síntesi i l'avaluació de l'activitat anti-VIH d'espècies dimèriques. Aquest estudi ens ha portat al descobriment d'un compost de moderada activitat inhibitòria i de baixa citotoxicitat.
This PhD Thesis is aimed at the development of new methodologies for the modification of purine nucleobases. In particular, we studied their labeling with 15N. Nitrogen-labeling enjoy several interesting applications; among them, NMR of 15Nlabeled nucleobases has provided key information on local interactions involved in molecular recognition processes, such as hydrogen bonding, protonation, hydration and ligand interactions. On the other hand, we also focused our attention on the design and synthesis of new anti-HIV-1 nucleosides.
[1-15N]-Labeling of purine nucleosides was easily achieved from N-nitroinosines via a simple ring opening-ring closing mechanism. Unfortunately, this procedure cannot be applied to 2'-deoxyinosines due to depurination processes during the nitration reaction. To overcome this difficulty, in chapters 1 and 2, we investigated the reaction of other N1-activated inosines (the 1-sulphonylinosines) with amines.
Several sulphonyl groups were tested: triflyl, mesyl, tosyl, 4-nitrobenzenesulphonyl, 2,4-dinitrobenzenesulphonyl, 2-nitrobenzenesulphonyl, trimethylbenzenesulphonyl, triisopropylbenzenesulphonyl and pentafluorobenzenesulphonyl. Among them, the 2 -nitrobenzenesulphonyl group turned out to be the most appropriate choice in the reaction with labeled ammonia; and the 2,4-dinitrobenzenesulphonyl gave also good results in the reaction with alkylamines.
In the third chapter we explored a different rearrangement mechanism that allowed us the facile conversion of 2,4-dinitrobenzenesulphonylinosines into [115N]adenosines, [1-15N]-2'-deoxyadenosines, and 1-alkyladenosines.
Labeling of the amino group of purines focused also our attention. In this connection, in the fourth chapter we studied the Pd-catalyzed coupling of 6- and 2- halopurine nucleosides with synthetic equivalents of ammonia as the label source. This novel approach allowed us a straightforward preparation of double-labeled adenosines, 2'-deoxyadenosines, and [2-15NH2]guanosines, under mild conditions and by using only stoichiometric amounts of the 15N labeled reagent.
Finally, in the fifth chapter, we designed and synthesized new dimeric nucleosidic species aimed at the inhibition of the reverse transcriptase enzyme of the HIV-1.