A technology for optimization of potential parameters from condensed phase simulations (POP) is discussed and illustrated. It is based on direct calculations of the derivatives of macroscopic observables with respect to the potential parameters. The derivatives are used in a local minimization scheme, comparing simulated and experimental data. In particular, we show that the Newton Trust-Region protocol allows for accurate and robust optimization. POP is illustrated for a toy problem of alanine dipeptide and is applied to folding of the peptide WAAAH. The helix fraction is highly sensitive to the potential parameters while the slope of the melting curve is not. The sensitivity variations make it difficult to satisfy both observations simultaneously. We conjecture that there is no set of parameters that reproduces experimental melting curves of short peptides that are modeled with the usual functional form of a force field. We then apply the newly developed technology to study the liquid mixture of tert-butanol and water. We are able to obtain, after 4 iterations, the correct phase behavior and accurately predict the value of the Kirkwood Buff (KB) integrals. We further illustrate that a potential that is determined solely by KB information, or the pair correlation function, is not necessarily unique. / text

Expansionen komprimierter Fluide finden breite Anwendung und werden hier mit Hilfe der Schwingungsspektroskopie untersucht. Dabei ist der Aggregatzustand der bei der Zerstäubung entstehenden Partikel von besonderem Interesse. In Abhängigkeit von Stagnationsdruck, Düsentemperatur, und Düsenabstand werden neben Lachgas tert-Butylalkohol und n-Pentan hinsichtlich ihrer Partikelbildung charakterisiert. Die Ergebnisse bilden eine Grundlage für die Expansion nahkritischer Lösungen.

Première partie: Les adénomes hépatocellulaires (AHC) sont des tumeurs bénignes qui se développent le plus souvent chez la femme jeune suite à la prise de contraceptifs oraux. Ils sont classés, sur le plan moléculaire, en: 1) AHC inflammatoires (AHCI), caractérisés par des mutations de différents gènes (IL6ST, GNAS ou STAT3) entrainant une activation de la voie de signalisation de l'interleukine 6; 2) les AHC avec mutations biallèliques inactivatrices d'HNF1A (H-AHC); 3) les AHC mutés pour CTNNB1 (bAHC) qui présentent un risque accru de transformation maligne et 4) les AHC non classés (UAHC). La glycogénose de type I (GSD I) est une maladie métabolique héréditaire rare qui prédispose au développement des AHC. Cependant les principales études moléculaires des AHC ont été réalisées sur des tumeurs sporadiques, et le profil moléculaire des AHC associée à la GSDI reste à déterminer.L'objectif de notre a été de caractériser, par des techniques de séquencage et de PCR quantitative, les altérations moléculaires d'une série d'AHC développés chez les patients atteints de GSD. Nous avons mis en évidence que le profil des AHC développés dans un contexte de GSDI était différent de celui des AHC sporadiques, avec aucun H-AHC et une tendance vers une augmentation de la fréquence des mutations de CTNNB1. Nous avons également observé que les foies non tumoraux des patients atteints de GSDI présentaient différentes anomalies métaboliques (répression de la néoglucogenèse et activation de la glycolyse et de la synthèse des acides gras) également retrouvées dans les H-AHC sporadiques. Ces anomalies sont d'autre connues pour favoriser la cancérogénèse. Notre étude a ainsi démontré que la GSDI prédisposait à des AHC de sous type moléculaire particulier, elle a également identifié diverses anomalies métaboliques observées dans les foies non tumoraux des patients atteints de GSDI qui pourraient contribuer au développement des tumeurs. Deuxième partie: Le carcinome hépatocellulaire (CHC), développé à partir des hépatocytes, est la tumeur maligne hépatique primitive la plus fréquente. Il représente le cinquième cancer le plus fréquent dans le monde et la troisième cause de mortalité liée au cancer. Il se développe dans environ 80% des cas dans un contexte d'hépatopathie chronique, sur parenchyme cirrhotique. Le processus de transformation maligne de la cirrhose en CHC est séquentiel, et passe par différentes étapes prénéoplasiques, comme les macronodules de bas ou haut grade. Il a récemment été mis en évidence que l'anomalie moléculaire la plus fréquente dans le CHC était les mutations du promoteur de TERT, gène codant pour la télomérase. Le but de notre étude a été d'étudier si ces mutations étaient également présente dans une série de 96 nodules développés sur cirrhose. Dans 31 cas, nous avons également déterminer le statut mutationnel de 10 gènes fréquemment mutés dans le CHC. L'ensemble des nodules a fait l'objet d'une relecture par 6 anatomopathologistes spécialisés en pathologie hépatique, et l'expression de marqueurs immunohistochimiques de malignité (Glypican 3, heat Shock protein 70, Glutamine Synthetase) a été évaluée. Nous avons identifié des mutations dans 6% des macronodules de bas grade, 20% des macronodules de haut grade, et dans environ 50% des nodules transformés en CHC. L’existence de mutations était corrélée à plusieurs critères morphologiques et immunohistochimiques de malignité. Aucune mutation dans un des 10 autres gènes fréquemment mutés dans le CHC n’a été retrouvée. Nos résultats démontrent que la fréquence des mutations du promoteur de TERT augmente au cours de la carcinogénèse hépatique, et qu’il s’agit d’une anomalie très précoce qui pourrait constituer un biomarqueur d'évaluation du risque de transformation des lésions prénéoplasiques développées sur cirrhose. / First Part: Hepatocellular adenomas (HCA) are benign tumors which most often develop in young women taking oral contraceptives. They are classified as : 1) inflammatory HCA (IHCA), characterized by mutations of genes (IL6ST, GNAS, STAT3) involved in the interleukin 6 pathway; 2) HCA with biallelic inactivating mutations of HNF1A (H-HCA) ; 3) CTNNB1 mutated HCA (bAHC), which harbour a high risk of malignant transformation and 4) unclassified HCA (UHCC). Glycogen storage disease type 1 (GSD1) is a rare hereditary metabolic disease that predispose to HCE development. The main molecular studies of HCA were pervformed on sporadic cases, and the molecular profile of HCA associated to GSDI remains to be investigated. The aim of our study was to characterize, by gene sequencing and gene expression profiling, a series of HCA developed in patients with GSD1. The molecular profile of GSD1 HCA was different to that of sporadic HCA, with a lack of H-HCA and a high frequency of b-HCA. We also observed that non tumoral livers of GSD1 patients featured several metabolic alterations (gluconeogenesis repression, glycolysis and fatty acid synthesis activation) that were also observed in sporadic H-HCA and may favor carcinogenesis. Alltogether, our study demonstrated that GSD1 predispose to particular HCA subtypes and the metabolic alterations observed in non tumorl liver of GSD1 patients may contribute to tumor formation. Second Part: Hepatocellular carcinoma (HCCIt is the fifth most frequent cancer and the third cause of cancer related death worldwide. If TERT promoter mutations are, so far, the most frequent recurrent molecular alterations of HCC, genetic determinants of the early steps of carcinogenesis on cirrhosis are still poorly understood. We aimed to evaluate the occurrence of telomerase reverse transcriptase (TERT) promoter mutations in a series of 96 macrondouels developed in a cirrhotic background. For 30 cases, 10 genes frequently mutated in HCC were also screeened. Six liver pathologists reviewed all the samples, and mmunohistochemistry (IHC) analyses were performed for glypican 3, glutamine synthase, and heat shock protein 70. TERT promoter mutations were highly related to the step-wise hepatocarcinogenesis because mutations were identified in 6% of low grade dysplastic nodules, 19% of high grade dysplastic nodules, 61% of high grade nodules with foci of transformation into HCC, and 42% of small HCC. Mutations in the 10 genes recurrently mutated in HCC were only identified in 28% of the small HCC. In conclusion, Frequency of TERT promoter mutations rapidly increases during the different steps of the transformation of premalignant lesions into HCC on cirrhosis. Consequently, somatic TERT promoter mutation is a new biomarker predictive of transformation of premalignant lesions into HCC.

Objective: Hepatocellular carcinoma (HCC) often develops in patients with alcohol-related cirrhosis at an annual risk of up to 2.5%. Some host genetic risk factors have been identified but do not account for the majority of the variance in occurrence. This study aimed to identify novel susceptibility loci for the development of HCC in people with alcohol related cirrhosis. - Design: Patients with alcohol-related cirrhosis and HCC (cases: n=1214) and controls without HCC (n=1866), recruited from Germany, Austria, Switzerland, Italy and the UK, were included in a two-stage genome-wide association study using a case–control design. A validation cohort of 1520 people misusing alcohol but with no evidence of liver disease was included to control for possible association effects with alcohol misuse. Genotyping was performed using the InfiniumGlobal Screening Array (V.24v2, Illumina) and the OmniExpress Array (V.24v1-0a, Illumina). - Results: Associations with variants rs738409 in PNPLA3 and rs58542926 in TM6SF2 previously associated with an increased risk of HCC in patients with alcohol-related cirrhosis were confirmed at genome-wide significance. A novel locus rs2242652(A) in TERT (telomerase reverse transcriptase) was also associated with a decreased risk of HCC, in the combined meta-analysis, at genome-wide significance (p=6.41×10⁻⁹, OR=0.61 (95% CI 0.52 to 0.70). This protective association remained significant after correction for sex, age, body mass index and type 2 diabetes (p=7.94×10⁻⁵, OR=0.63 (95% CI 0.50 to 0.79). Carriage of rs2242652(A) in TERT was associated with an increased leucocyte telomere length (p=2.12×10⁻⁴⁴). - Conclusion: This study identifies rs2242652 in TERT as a novel protective factor for HCC in patients with alcohol-related cirrhosis.

No description available.

Recently, clathrate hydrate has attracted much attention because of its energy gas enclathration phenomenon. Since energy gas such as methane, ethane, and hydrogen could be stored in solid hydrate form, clathrate hydrate research has been considerably focused on energy gas storage and transportation medium. Especially, methane hydrate, which is crystalline compound that are formed by physical interaction between water and relatively small sized guest molecules, can contain about as much as 180 volumes of gas at standard pressure and temperature condition. To utilize gas hydrate as energy storage and transportation medium, two important key features: storage capacity and storage condition must be considered. Herein, we report the inclusion phenomena of methane occurred on tert-butyl alcohol hydrate through thermodynamic measurement and spectroscopic analysis by using powder X-ray diffractometer, and 13C solidstate NMR. From spectroscopic analysis, we found the formation of sII type (cubic, Fd3m) clathrate hydrate by introducing methane gas into tert-butyl alcohol hydrate whereas tert-butyl alcohol hydrate alone does not form clathrate hydrate structure. Under equilibrium condition, pressure-lowering effect of methane + tert-butyl alcohol double hydrate was also observed. The present results give us several key features for better understanding of inclusion phenomena occurring in the complex hydrate systems and further developing methane or other gas storage and transportation technique.

Thesis (Ph. D.)--Worcester Polytechnic Institute. / Keywords: Water; Adsorption; Molecular simulation; Nanoporous materials. Includes bibliographical references (p. 117-119).

Made available in DSpace on 2016-06-02T20:36:44Z (GMT). No. of bitstreams: 1 5184.pdf: 2838409 bytes, checksum: 855df3c811457d71bb20ef1cd94525c3 (MD5) Previous issue date: 2013-02-28 / Universidade Federal de Minas Gerais / In this work some studies about the synthesis of a new Znphthalocyanine derivative containing 8 tert-butyl groups on peripheral positions were performed. In order to obtain this compound, a new monomeric unit were synthesized 4,5-di-tert-butylphthalonitrile where a Diels-Alder reaction between a cyclic sulfone (diene) and a dinitrile (dienophile) was the key step. Beyond the synthesis and structural characterization of this phthalocyanine, preliminary photophysical studies to verify potential applications of this compound as photosensitizer were performed. To reach the 4,5-dissubstituted phthalonitrile 8, firstly, thiophene 5 was synthesized (SCHEME 8). After established the methodology to provide 5 in good yield, some tests between 5 and fumaronitrile (6) on cycloaddition conditions were performed, however, as expected, no reaction occurred, and the starting materials were recovered (SCHEME 9). Aiming at the raising diene 5 reactivity, this compound was oxidized to sulfone 9 (SCHEME 10). After that, some test between the sulfone 9 and fumaronitrile (6) were performed. The objective was to achieve a one-pot 3 steps reaction (Diels-Alder SO2 cheletropic elimination oxidation). However compound 8 was reached only in poor yields (SCHEME 10). To overcome the poor yields, some dinitrilic dienophiles were proposed. For example, dicyanoacetylene 10 (SCHEME 11) could furnish the phthalonitrile 8 after a cycloaddition and SO2 elimination. However, dicyanoacetylene (10) showed not to be accessible, and, in our hands, it was not possible to obtain with literature available procedures. According to literature, the insertion of halogens in dinitrilic dienophiles greatly raises its reactivity for cycloaddition reactions. Then, the bromination of fumaronitrile (6) to obtain the dienophile 13 was performed (SCHEME 12). After compound 13 was reached, some tests with diene 9 were done. The 4,5-di-tertbutylphthalonitrile (8) was obtained in 50% yield in a solvent-free three step domino sequence (Diels-Alder SO2 cheletropic elimination HBr elimination). Studies to obtain the phthalocyanine 14 were performed (SCHEME 13). Firstly, a current methodology in literature were tested which uses DMAE/140°C/Zn(OAc)2, however the best obtained result for 14 was only 7% yield. In addition, many polymeric byproducts were observed. Another tested methodology was the addition of phthalonitrile 8 in a solution of n-pentanol and its respective alcoxide under heating. Phthalocyanine 15 was obtained in 22% yield in these conditions. When the tetramerization was performed and the crude product metallated using anhydrous Zn(OAc)2, phthalocyanine 14 was obtained in 21% yield (SCHEME 14). In both cases these results were optimized, and the results were in agreement with the literature. All synthesized compounds were fully characterized (1D and 2D NMR, UV-Vis, IR), HRMS (ESI-TOF for compound 8 and MALDI-TOF for compounds 14 and 15) and low resolution mass spectroscopy (compounds 1, 2, 3, 4, 5 and 9). Preliminary photophysical and photochemical studies for phthalocyanines 14 and 15 were performed (aggregation studies, singlet oxygen quantum yield, fluorescence quantum yield and photobleaching). The obtained results demonstrated compounds 14 and 15 fulfill some essential requirements for PDT studies. / Neste trabalho foram realizados alguns estudos sobre a síntese de um novo derivado do tipo Zn-ftalocianina, contendo oito grupos tert-butil em suas posições periféricas. Para isso, iniciamos com a síntese de uma nova unidade monomérica - 4,5-di-tert-butilftalonitrilo - tendo como etapa chave a reação de Diels- Alder entre uma sulfona cíclica (dieno) e um dienófilo dinitrílico. Além da síntese e caracterização estrutural desta nova ftalocianina, foram realizados alguns estudos fotofísicos preliminares visando apontar algumas aplicações deste corante enquanto fotossensibilizador. Para obter o ftalonitrilo 4,5-dissubstituído, inicialmente foi realizada a síntese do tiofeno 5, como descrito no ESQUEMA 1. Estabelecida a metodologia que forneceu 5 em melhor rendimento, foram realizados alguns testes de cicloadição entre o tiofeno 5 e o fumaronitrilo (6), porém, como esperado, a reação não ocorreu, sendo possível recuperar os materiais de partida (ESQUEMA 2). Visando aumentar a reatividade do dieno 5, foi realizada uma oxidação para a sulfona 9 (ESQUEMA 3). Alguns testes de cicloadição foram realizados, utilizando a sulfona 9 e o fumaronitrilo (6). Neste caso, o objetivo foi realizar uma reação one-pot com três etapas reacionais (Diels-Alder - eliminação queletrópica de SO2 - oxidação). O composto 8 foi obtido, entretanto, apenas em baixos rendimentos (5-19%) (ESQUEMA 3). Visando contornar os baixos rendimentos de obtenção de 8, propusemos alguns outros dienófilos dinitrílicos. Por exemplo, o dicianoacetileno (10) (ESQUEMA 4), que forneceria diretamente o ftalonitrilo 8 após uma cicloadição e eliminação de SO2. Entretanto, o dicianoacetileno (10) se mostrou um composto de difícil obtenção, sendo que, em nossas mãos, não foi possível obtê-lo com o procedimento descrito na literatura. De acordo com a literatura, a inserção de halogênios em dienófilos dinitrílicos aumenta muito sua reatividade frente a reações de cicloadição. Assim, partindo dessa informação, foi realizada a bromação do fumaronitrilo (6) visando obter o dienófilo 13 (ESQUEMA 5). Após a obtenção de 13 foram realizados alguns testes fazendo reagir 13 com o dieno 9, sendo que, na ausência de solvente, obtevese o 4,5-di-tert-butilftalonitrilo (8) com 50% de rendimento em um processo one-pot de 3 etapas (Diels-Alder eliminação queletrópica de SO2 eliminação de HBr). Após realizar a síntese do ftalonitrilo 8, foram iniciados os estudos para obtenção da respectiva ftalocianina de zinco octassubstituída 14 (ESQUEMA 6). Primeiramente foram testadas algumas metodologias de uso recorrente na literatura, utilizando-se DMAE/140oC/Zn(OAc)2, entretanto, o melhor resultado de formação 14 foi de apenas 7% de rendimento, além da formação de muitos polímeros. A próxima metodologia testada foi a adição do ftalonitrilo 8 em uma solução de n-pentanol anidro e seu respectivo alcóxido de sódio, sob aquecimento (ESQUEMA 7). Nestas condições foi obtida a ftalocianina não metalada 15 com 22% de rendimento. Quando a reação de tetramerização foi realizada e o produto reacional foi submetido à metalação com Zn(OAc)2 sem purificação prévia, o composto 14 foi isolado com 21% de rendimento (ESQUEMA 7). Em ambos os casos estes foram os melhores resultados obtidos após a otimização dos procedimentos, sendo que rendimentos em torno de 20% são compatíveis com a maioria das sínteses descritas na literatura destes compostos. Os compostos sintetizados neste trabalho foram caracterizados utilizando-se técnicas de espectroscopia de RMN 1D e 2D, espectroscopia na região do UV-Vis, espectroscopia na região do infravermelho, espectrometria de massas de baixa e espectrometria de massas de alta resolução (ESI-TOF e MALDI-TOF). Estudos fotofísicos e fotoquímicos preliminares foram realizados (estudos de agregação, rendimento quântico de oxigênio singlete, rendimento quântico de fluorescência e photobleaching) para as ftalocianinas 14 e 15. Os resultados obtidos indicaram que estes novos compostos reúnem algumas das características essenciais para uso enquanto fotossensibilizador em tratamentos de lesões por terapia fotodinâmica (PDT), por exemplo, ausência de agregação em solução e produção de oxigênio singlete.

L’éthyl tert-butyl éther (ETBE) et le méthyl tert-butyl éther (MTBE) sont des éthers carburants utilisés comme additifs dans les essences sans plomb. Du fait de leur utilisation massive, de nombreux cas de pollutions d’aquifères ont été répertoriés, en particulier pour le MTBE, et ces composés représentent donc un risque sanitaire potentiel. Des travaux récents ont permis de mettre en évidence différents micro-organismes capables de dégrader ces composés malgré leur faible biodégradabilité dans l'environnement. Néanmoins, une meilleure compréhension de l'écologie et de la régulation de ces capacités de dégradation permettrait une meilleure gestion de la bioremédiation de sites contaminés par l'ETBE ou le MTBE.L’objectif de la thèse, réalisée dans le cadre d'un projet ANR Blanc (MiOxyFun), est de mieux comprendre l'écologie des communautés microbiennes impliquées dans la dégradation de ces éthers et leur relation avec la régulation ainsi qu'avec les cinétiques de dégradation de ces composés par des membres spécifiques de ces communautés. Ainsi, à partir de différents échantillons environnementaux venant de sites pollués par l'ETBE ou le MTBE, des enrichissements ont pu être réalisés en laboratoire afin d'étudier leurs microflores. Ces enrichissements ont été étudiés notamment pour leurs cinétiques de dégradation, la composition de leurs communautés bactériennes, et pour l'isolement de souches bactériennes directement impliquées dans la dégradation de ces composés. L'étude des cinétiques de dégradation de l'ETBE ou du MTBE par différents enrichissements obtenus sur ETBE (cinq) et sur MTBE (six) a permis de montrer des profils de dégradation très différents. La dégradation était généralement lente et s'accompagnait d'un faible rendement en biomasse avec parfois accumulation transitoire de tert-butanol (TBA). Les capacités de dégradation d'autres composés des essences (BTEXs et n-alcanes) étaient aussi différentes d'un enrichissement à l'autre, le benzène, entre autres, étant dégradé par 10/11 enrichissements. Des techniques d'empreinte moléculaire (RISA, DGGE) ont permis de constater que les communautés bactériennes présentes dans les cinq enrichissements sur ETBE étaient différentes de celles sur les enrichissements sur MTBE. Les enrichissements sur ETBE ont fait spécifiquement l'objet d'une étude par analyse de banques de clones réalisées à partir des gènes codant l'ARNr 16S de ces enrichissements. Cette étude a montré la prédominance des Proteobacteria dans trois enrichissements, la prédominance des Acidobacteria dans un autre ainsi qu'une composition plus héterogène dans le cinquième. De plus, des Actinobacteria ont été détectées dans les 5 enrichissements.En parallèle, plusieurs souches possédant des capacités de dégradation ont été isolées des enrichissements: Rhodococcus sp. IFP 2040, IFP 2041, IFP 2042, IFP 2043 (dégradant l'ETBE jusqu'au TBA), une Betaproteobacteria IFP 2047 (dégradant l'ETBE), Bradyrhizobium sp. IFP 2049 (dégradant le TBA), Pseudonocardia sp. IFP 2050 (dégradant l'ETBE et le MTBE), Pseudoxanthomonas sp. IFP 2051 et une Proteobacteria IFP 2052 (dégradant le MTBE). Une étude par qPCR sur les gènes codant l'ARNr 16S a montré la prédominance de certaines souches isolées dans les enrichissements ETBE. Enfin, plusieurs gènes connus comme étant impliqués dans la dégradation des éthers carburants ont pu être mis en évidence dans les enrichissements et dans certaines des souches isolées. / ETBE and MTBE are fuel oxygenates added to unleaded gasoline to improve combustion. Due to their extensive use, numerous aquifers have been contaminated, particularly by MTBE. The use of ETBE and MTBE is considered to represent an environmental risk. Recent research has uncovered a range of microorganisms capable of degrading these compounds, even though their environmental half-lives are long. Improved understanding of the ecology and regulation of this degradative ability could improve the management of the ETBE and MTBE contaminated site remediation. The aim of this work, taking place in the framework of the ANR project MiOxyFun was to investigate the ecology of ETBE- and MTBE-degrading microbial communities and their relationship to the regulation and kinetics of ETBE- and MTBE-degradation by specific members of these communities. Several ETBE- and MTBE-degrading microbial communities were enriched in the laboratory from environmental samples from contaminated sites throughout the world. These enrichments were examined for their degradation kinetics, microbial community structure, and used to isolate specific community members actively degrading ETBE and/or MTBE. The ETBE or MTBE biodegradation kinetics of the five ETBE- and six MTBE- degrading enrichments demonstrated a diversity of biodegradation rates. Overall, biodegradation was generally slow and associated to a low biomass yield. Tert-butanol (TBA) was transiently produced in several cases. Biodegradation of other gasoline compounds (BTEXs and n-alkanes) was tested and varied among the enrichments studied. Benzene, however, was degraded in 10 out of the 11 enrichments. DNA fingerprinting techniques (RISA, DGGE) showed that the microflora present in the five ETBE enrichments were different from those of the MTBE enrichments. The ETBE enrichments were studied further by sequencing the 16S rRNA genes extracted, amplified and cloned from these enrichments. Proteobacteria dominated three of the ETBE enrichments, Acidobacteria in another one, and a more heterogeneous composition was found in the fifth ETBE enrichment. Actinobacteria were detected in all five enrichments. Several strains with ETBE or MTBE degradation capacities were isolated: Rhodococcus sp. IFP 2040, IFP 2041, IFP 2042, IFP 2043 (degrading ETBE to TBA),a Betaproteobacteria IFP 2047 (degrading ETBE), Bradyrhizobium sp. IFP 2047 (degrading TBA), Pseudonocardia sp. IFP 2050 (degrading ETBE and MTBE), Pseudoxanthomonas sp. IFP 2051 and a Proteobacteria IFP 2052 (degrading MTBE). Quantification of the 16S rRNA gene confirmed the relatively high number of these isolates in some of the ETBE enrichments. Several genes involved in ETBE and/or MTBE biodegradation were detected in some of the enrichments and in some of the isolated strains.

yes / The Forkhead transcription factor, FoxO3a induces genomic death responses in neurones following translocation from the cytosol to the nucleus. Nuclear translocation of FoxO3a is triggered by trophic factor withdrawal, oxidative stress and the stimulation of extrasynaptic NMDA receptors. Receptor activation of phosphatidylinositol 3-kinase (PI3K)-Akt signalling pathways retains FoxO3a in the cytoplasm, thereby inhibiting the transcriptional activation of death-promoting genes. We hypothesized that phenolic antioxidants such as tert-Butylhydroquinone (tBHQ), which is known to stimulate PI3K-Akt signalling, would inhibit FoxO3a translocation and activity. Treatment of cultured cortical neurones with NMDA increased the nuclear localization of FoxO3a, reduced the phosphorylation of FoxO3a, increased caspase activity and up-regulated Fas ligand expression. In contrast the phenolic antioxidant, tBHQ, caused retention of FoxO3a in the cytosol coincident with enhanced PI3K- dependent phosphorylation of FoxO3a. tBHQ-induced nuclear exclusion of FoxO3a was associated with reduced FoxO-mediated transcriptional activity. Exposure of neurones to tBHQ inhibited NMDA-induced nuclear translocation of FoxO3a, prevented NMDA-induced up-regulation of FoxO-mediated transcriptional activity, blocked caspase activation and protected neurones from NMDA-induced excitotoxic death. Collectively, these data suggest that phenolic antioxidants such as tBHQ oppose stress-induced activation of FoxO3a and therefore have potential neuroprotective utility in neurodegeneration.