SirT1 is a class III histone deacetylase that has beneficial roles in various diseases related to aging such as cancer, diabetes and neurodegenerative disease. Resveratrol is a natural compound that mimics most of the beneficial effects attributed to SirT1. Resveratrol has toxicity towards cancer cells and has been reported to be a direct activator of SirT1. Interestingly, SirT1 over-expression has also been reported to be toxic. We set out to determine if resveratrol toxicity is mediated through activation of SirT1. We have assessed resveratrol toxicity in embryonic stem cells and mouse embryonic fibroblast (MEFs) across different SirT1 genotypes. Our data indicates that SirT1 is not implicated in resveratrol toxicity in either normal or transformed MEFs. Thus, resveratrol toxicity does not appear to be mediated by SirT1.

SirT1 is a class III histone deacetylase that has beneficial roles in various diseases related to aging such as cancer, diabetes and neurodegenerative disease. Resveratrol is a natural compound that mimics most of the beneficial effects attributed to SirT1. Resveratrol has toxicity towards cancer cells and has been reported to be a direct activator of SirT1. Interestingly, SirT1 over-expression has also been reported to be toxic. We set out to determine if resveratrol toxicity is mediated through activation of SirT1. We have assessed resveratrol toxicity in embryonic stem cells and mouse embryonic fibroblast (MEFs) across different SirT1 genotypes. Our data indicates that SirT1 is not implicated in resveratrol toxicity in either normal or transformed MEFs. Thus, resveratrol toxicity does not appear to be mediated by SirT1.

SirT1 is a class III histone deacetylase that has beneficial roles in various diseases related to aging such as cancer, diabetes and neurodegenerative disease. Resveratrol is a natural compound that mimics most of the beneficial effects attributed to SirT1. Resveratrol has toxicity towards cancer cells and has been reported to be a direct activator of SirT1. Interestingly, SirT1 over-expression has also been reported to be toxic. We set out to determine if resveratrol toxicity is mediated through activation of SirT1. We have assessed resveratrol toxicity in embryonic stem cells and mouse embryonic fibroblast (MEFs) across different SirT1 genotypes. Our data indicates that SirT1 is not implicated in resveratrol toxicity in either normal or transformed MEFs. Thus, resveratrol toxicity does not appear to be mediated by SirT1.

Submitted by VANESSA CRISTINA FRANCISCO null (vanessacristina15@yahoo.com.br) on 2017-01-20T10:57:41Z No. of bitstreams: 1 Dissertacao VANESSA FRANCISCO.pdf: 1752576 bytes, checksum: 912fec76d80b6e05e9423678e6ef2d46 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2017-01-24T16:31:32Z (GMT) No. of bitstreams: 1 francisco_vc_me_arafcf.pdf: 1752576 bytes, checksum: 912fec76d80b6e05e9423678e6ef2d46 (MD5) / Made available in DSpace on 2017-01-24T16:31:32Z (GMT). No. of bitstreams: 1 francisco_vc_me_arafcf.pdf: 1752576 bytes, checksum: 912fec76d80b6e05e9423678e6ef2d46 (MD5) Previous issue date: 2016-11-17 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O aroma, além da textura, é um dos atributos sensoriais mais importantes para a aceitação da carne bovina pelo consumidor. O aroma da carne é influenciado por fatores como dieta, sistema de produção (pasto ou confinamento), raça, sexo, idade ao abate, maturação, corte e método de cocção. Entre os principais compostos responsáveis pelo aroma em carnes estão os aldeídos, cetonas e compostos sulfurados, provenientes de reações químicas tais como reação de Maillard, reações de oxidação de lipídios e degradação da tiamina. Várias técnicas de extração têm sido utilizadas para a análise de compostos voláteis em carnes, dentre elas, a extração-destilação simultânea (Simultaneous Distillation/ Extraction - SDE), headspace dinâmico e a MEFS (microextração em fase sólida). Atualmente esta última é a mais utilizada, por ser uma técnica rápida, fácil e não necessitar do uso de solventes. Tendo em vista que há poucos trabalhos no Brasil sobre compostos voláteis em carne bovina, este trabalho objetivou otimizar as condições de extração por MEFS para a caracterização de compostos voláteis em carne bovina bem como determinar o perfil qualitativo destes compostos em carne proveniente de animais cruzados terminados a pasto ou confinamento. No primeiro experimento deste estudo, foram testados seis diferentes tipos de materiais de recobrimento de MEFS quanto a sua eficiência na extração de compostos voláteis em carne bovina: 75 µm CAR/PDMS (Carboxen/ Polidimetilsiloxano), 65 µm PDMS/DVB (Polidimetilsiloxano/Divinilbenzeno), 50/30 µm DVB/CAR/PDMS (Divinilbenzeno/ Carboxen/ Polidimetilsiloxano), 100 µm PDMS (Polidimetilsiloxano), 70 µm CAR (Carboxen) e 85 µm PA (Poliacrilato), bem como foram otimizadas as condições de extração utilizando a metodologia de superfície de resposta. As análises foram realizadas por cromatografia em fase gasosa acoplada ao detector de ionização em chama (CG-DIC) e cromatografia em fase gasosa acoplada à espectrometria de massas (CG-EM), sendo aplicado um planejamento experimental do tipo delineamento composto central rotacional (DCCR), baseado num planejamento fatorial 22. As fibras de fase mista foram as que apresentaram melhores resultados, sendo que a fibra CAR/PDMS foi a que extraiu o maior número de compostos, nas condições de extração otimizada de 65 minutos a 60 °C. No segundo experimento, para caracterização do perfil químico dos compostos voláteis em carne de animais cruzados, foi utilizada a carne de animais de quatro grupos genéticos, machos não castrados e fêmeas, filhos de vacas cruzadas ½ Angus x ½ Nelore (TA) ou ½ Simental x ½ Nelore (TS) com Touros Angus ou Limousin terminados a pasto ou confinamento. Foram encontrados 94 compostos das seguintes classes químicas: alcanos (29), aldeídos (18), compostos sulfurados (10), compostos aromáticos (9), cetonas (9), alcoóis (7), ácidos carboxílicos (7), éteres (4), compostos nitrogenados (3) e lactona (1). Os principais efeitos foram observados no sistema de produção (confinamento ou pasto) e raça do touro (Angus ou Limousin), sendo encontrados 4 compostos e 12 compostos com diferenças significativas (p<0,05) respectivamente. Os compostos provenientes da oxidação de lipídios como hexanal, heptanal, 3-hidroxi-2-butanona, 1-octen-3-ol, 1-hexanol e 2,3-octanodiona foram os que mais se destacaram e são importantes marcadores que contribuem para a formação do aroma de carne bovina assada. / CNPq: 134462/2014-9

SirT1 is a class III histone deacetylase that has beneficial roles in various diseases related to aging such as cancer, diabetes and neurodegenerative disease. Resveratrol is a natural compound that mimics most of the beneficial effects attributed to SirT1. Resveratrol has toxicity towards cancer cells and has been reported to be a direct activator of SirT1. Interestingly, SirT1 over-expression has also been reported to be toxic. We set out to determine if resveratrol toxicity is mediated through activation of SirT1. We have assessed resveratrol toxicity in embryonic stem cells and mouse embryonic fibroblast (MEFs) across different SirT1 genotypes. Our data indicates that SirT1 is not implicated in resveratrol toxicity in either normal or transformed MEFs. Thus, resveratrol toxicity does not appear to be mediated by SirT1.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Colorectal cancer is one of the most common cancer types worldwide. Both genetic and epigenetic alterations play a critical role in its initiation and progression. One of the genes frequently epigenetically silenced or lost in many types of human cancer is tumor suppressor gene Hypermethylated in Cancer 1 (HIC1). It encodes for transcriptional repressor regulating its target genes directly or indirectly. Twelve genes whose expression is repressed by HIC1 have been identified to date. These genes encode for transcription factors, cell cycle and apoptosis regulators or proteins involved in angiogenesis as well as cell migration and invasiveness. Employing mouse embryonic fibroblasts upon Hic1-conditional knockout we have revealed six novel genes potentially repressed by Hic1 including Toll-like receptor 2 (Tlr2). Here we show that Tlr2 is one of the Hic1 target genes and that Hic1 inactivation in the intestine leads to increased Tlr2 production. Moreover, enhanced inflammatory response upon chemical-induced colitis as well as increased tumor formation in ApcMin mice was observed in Hic1-deficient mice. Expression profiling in human fibroblast upon HIC1 knockdown revealed increased expression of another potential target gene, transcription factor E2F7. Our study describes a new relationship between HIC1 and...

DNA DSBs are most toxic to cells because they can lead to genomic rearrangements and even cell death. Most DSBs induced by ionizing radiation or radiomimetic drugs such as calicheamicin and bleomycin, bear 3′-phosphate or 3′- PG moieties that must be removed to allow subsequent gap filling and ligation. DSBs can be repaired by two main pathways: the homologous recombination (HR) pathway and the non-homologous end-joining (NHEJ) pathway, NHEJ is the primary repair pathway in mammalian cells. While HR repairs single strand breaks (SSBs) or DSBs accurately by using an undamaged copy of the sequence mostly at late S phase and G2 phase, the NHEJ pathway repairs DSBs without the requirement for sequence homology in a processing that may be error-free or error- prone and is most active at G1 phase. TDP1 is a DNA repair enzyme in both pathways, It associates with DNA SSB repair proteins XRCC1 and DNA ligase III and plays a role in processing of topoisomerase I- mediated SSBs. Our early results suggested that TDP1 also can remove protruding 3’- PG and other 3’ blocks from DSBs ends in vitro. A homozygous H493R mutation in the active site of TDP1 causes spinocerebellar ataxia with axonal neuropathy (SCAN1), a rare autosomal recessive genetic disease with neurological symptoms including peripheral neuropathy. DNA damage and misrepair can be determined by measuring the incidence of chromosomal aberrations such as rings, breaks, dicentrics, acentric fragments, and translocations in metaphase cells, and micronuclei in interphase cells. To assess the possible role of TDP1 in DSB repair in intact cells, the radiosensitivity of SCAN1 cells was determined by using a dose-fractionation method of irradiation. The data indicated that, when exposed to fractionated radiation doses, the SCAN1 cells were more sensitive than normal cells. Moreover, following treatment of cells with calicheamicin, SCAN1 cells showed a significantly higher incidence of dicentric chromosomes, acentric fragments, and micronuclei compared to normal cells, indicating that calicheamicin-induced DSBs were repaired less accurately and less efficiently, or more slowly in SCAN1 cells than in normal cells. All these results are consistent with a role for TDP1 in repair of 3’-PG DSBs in vivo. Oxidative stress is thought to induce replicative senescence and DNA damage in mouse embryo fibroblasts (MEFs). To determine the possible roles of oxidative stress on Tdp1-deficient MEFs, Tdp1-knockout MEFs and normal MEFs were cultured in 20% oxygen (atmospheric) and 3% (physiological) oxygen. The data from growth assays indicated that normal MEFs showed replicative senescence in 20% oxygen but not in 3% oxygen. Tdp1-knockout MEFs showed very poor growth compared to Tdp1 normal MEFs in both oxygen conditions, clearly suggesting an influence of repair of Tdp1 on oxidative stress induced DNA-DSBs in MEFs. Taken together, our results indicated that TDP1 is capable of removing protruding 3’-PG from DSB ends in intact cells. Moreover, DSBs induced by oxidative stress were repaired more slowly or inefficiently in MEFs when Tdp1 is absent, resulting in cell cycle arrest and poor cell growth.

SOUZA, Francisco Thiago Correia de. Validação e determinação de carbofurano e carbaril em plasma sanguíneo de agricultores do perímetro irrigado do baixo Jaguaribe-CE por MEFS-HS/CG-EM. 2014. 89 f. Dissertação (Mestrado em química)- Universidade Federal do Ceará, Fortaleza-CE, 2014. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-10-11T14:37:03Z No. of bitstreams: 1 2014_dis_ftcsouza.pdf: 1510094 bytes, checksum: 558971bf2d922838752f45e145b0532f (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2016-10-11T18:25:16Z (GMT) No. of bitstreams: 1 2014_dis_ftcsouza.pdf: 1510094 bytes, checksum: 558971bf2d922838752f45e145b0532f (MD5) / Made available in DSpace on 2016-10-11T18:25:16Z (GMT). No. of bitstreams: 1 2014_dis_ftcsouza.pdf: 1510094 bytes, checksum: 558971bf2d922838752f45e145b0532f (MD5) Previous issue date: 2014 / The presence of pesticides is increasing concern in Brazil since 2007 to 2012, the volume of pesticides (considering only the active ingredient) applied to the crops grew 14 %. The uncontrolled use of these compounds has offered risks to workers and residents of the areas of agribusiness. A survey conducted by a group of Federal University of Ceará, showed that in 23 samples of water from the irrigated perimeter region of low Jaguaribe, collected at different locations and analyzed by liquid chromatography, all showed the presence of some pesticides, highlighting the carbaryl and carbofuran as the most detected. One study found chromosomal abnormalities in bone marrow cells of individuals exposed to pesticides in the region, which reinforces the need to develop bioanalytical methods able to detect pesticides in biological samples, for which exposure can be monitored by competent authorities. Based on that a method was developed for analysis of carbaryl and carbofuran, using a gas chromatograph equipped with mass detector, it was monitored the analytical signal of pesticides and their respective products of thermal degradation, degradation that occurred gun chromatograph. A study to determine the appropriate line speed for the method was carried out with the construction of the Van Deemter diagram, being determined as great as the speed of 50.5 cm s-1. Sample preparation was carried out with the precipitation of the plasma proteins microextraction followed by solid phase in the headspace (HS-SPME) of the supernatant; to extract optimization was performed factorial design with central component 22 in three fibers having different characteristics. The Polydimethylsiloxane/Divinylbenzene fiber (PDMS/DVB) of 65 μm showed a higher affinity for analytes and determined as optimum conditions the time of 40 min. extraction with NaCl 30 % w/v of ionic strength and temperature of 110 °C; pH 5.5, stirring speed of 1000 rpm and 40 ml vial were kept constant. A method for quantitative determination has been validated only for carbaryl, making monitored by signal 1-naphthol. The % 1-naphthol produced by thermal degradation of carbaryl in the conditions of SPME and GC-MS were respectively determined by NMR 8 % and 94 % as determined by the generated signal detector. The selectivity was evaluated in blood plasma matrix for normal, hemolyzed, and lipemic samples, the highly selective method. The linear response range was 12-180 μg L-1; using the matrix method of superposition using the substitute pattern as pirimicarb, the linearity of calibration curve was determined by the value of the correlation coefficient (R = 0.999), being conducted further study of the linearity. The values of detection and limit of quantification were 3.0 and 12.0 μg L-1, demonstrating that small concentrations can be analyzed by the method; the precision and accuracy intra and inter race were all within the recommended resolution by the National Sanitary Surveillance Agency No. 27/2012, less than 15% for medium to high concentrations and lower than 20 % for low concentrations. Samples of 10 workers in the region were analyzed, but was not detected presence of carbaryl and carbofuran in plasma of these individuals. / A presença dos agrotóxicos é cada vez mais preocupante no Brasil visto que entre 2007 e 2012, o volume de defensivos (considerando apenas o princípio ativo) aplicado nas lavouras cresceu 14 %. O uso descontrolado desses compostos tem oferecido riscos a trabalhadores e moradores das regiões do agronegócio. Uma pesquisa realizada por um grupo da Universidade Federal do Ceará, mostrou que em 23 amostras de água da região do perímetro irrigado do baixo Jaguaribe, coletadas em diferentes localidades e analisadas por cromatografia líquida, todas apresentaram a presença de algum agrotóxico, destacando-se o carbaril e o carbofurano como os mais detectados. Um estudo constatou anormalidades cromossômicas em células da medula óssea de indivíduos expostos a pesticidas na região, o que reforça a necessidade de desenvolvimento de métodos bioanalíticos capazes de detectar pesticidas em amostras biológicas, para que essa exposição possa ser monitorada pelas autoridades competentes. Baseado nisso um método foi desenvolvido para análise de carbaril e carbofurano, usando um cromatógrafo a gás equipado com detector de massas, em que foi monitorado o sinal analítico do agrotóxico e de seus respectivos produtos de degradação térmica, degradação essa ocorrida injetor do cromatógrafo. Um estudo para determinação da melhor velocidade linear para o método foi realizado com a construção do diagrama de Van Deemter, sendo determinada como ótima, a velocidade de 50,5 cm s-1. O preparo da amostra foi realizado com a precipitação das proteínas do plasma seguida de microextração em fase sólida no modo headspace (MEFS-HS) do sobrenadante; para otimização da extração foi realizado planejamento fatorial 22 com componente central, em 3 fibras com características diferentes. A fibra Polidimetilsiloxano/Divinilbenzeno (PDMS/DVB) de 65µm mostrou uma maior afinidade com os analitos, sendo determinada como condições ótimas o tempo de 40 min. de extração com NaCl 30 % p/v de força iônica e 110 °C de temperatura; o pH 5,5, agitação de 1000 rpm e vial de 40 mL foram mantidos constantes. Foi validado um método para determinação quantitativa apenas para o carbaril, sendo esse monitorado pelo sinal do 1-naftol. A % de 1-naftol produzido pela degradação térmica do carbaril, nas condições de MEFS e no CG-EM, foram respectivamente de 8% determinado por RMN e 94 % determinado pelo sinal gerado no detector EM. A seletividade foi avaliada na matriz de plasma sanguíneo para amostras normais, lipêmica e hemolisada, sendo o método bem seletivo. A faixa linear de trabalho foi de 12 a 180 µg L-1; utilizando o método de superposição da matriz com a utilização do pirimicarbe como padrão substituto, a linearidade da curva de calibração foi determinada pelo valor do coeficiente de correlação (R = 0,999), sendo realizado um estudo mais aprofundado da linealidade. Os valores do limite de detecção e quantificação foram de 3,0 e 12,0 µg L-1, o que demonstra que pequenas concentrações podem ser analisadas pelo método; a precisão e exatidão intra e inter corrida foram todos dentro do recomendado pela resolução da Agência Nacional de Vigilância Sanitária Brasileira nº 27/2012, menores que 15 % para concentrações médias e altas e, menores que 20 % para baixas concentrações. Amostras de 10 trabalhadores da região foram analisadas, porém não foi detectada presença de carbaril e carbofurano no plasma desses indivíduos.