986 resultados para Tiopurina metil transferase


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With the fast growth of cancer research, new analytical methods are needed to measure anticancer drugs. This is usually accomplished by using sophisticated analytical instruments. Biosensors are attractive candidates for measuring anticancer drugs, but currently few biosensors can achieve this goal. In particular, it is challenging to have a general method to monitor various types of anticancer drugs with different structures. In this work, a biosensor was developed to detect anticancer drugs by modifying carbon paste electrodes with glutathione-s-transferase (GST) enzymes. GST is widely studied in the metabolism of xenobiotics and is a major contributing factor in resistance to anticancer drugs. The measurement of anticancer drugs is based on competition between 1-chloro-2,4-dinitrobenzene (CDNB) and the drugs for the GST enzyme in the electrochemical potential at 0.1 V vs. Ag/AgCl by square wave voltammetry (SWV) or using a colorimetric method. The sensor shows a detection limit of 8.8 mu M cisplatin and exhibits relatively long life time in daily measurements. (C) 2014 Elsevier B.V. All rights reserved.

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As ciclodextrinas (CDs) são oligossacarídeos cíclicos que solubilizam e modificam moléculas por possuir uma cavidade interna hidrofílica e região externa hidrofóbica, com uma estrutura tronco-cônica, conferindo a estes açúcares cíclicos propriedades físico-químicas para complexação de uma grande variedade de moléculas. A enzima ciclodextrina glicosiltransferase (CGTase) catalisa reações de conversão de amido em diferentes tipos de CDs, a sua produção é influenciada por vários fatores. As pesquisas dirigidas para a produção de CGTases de menor custo são importantes para viabilizar economicamente o uso das CDs em escala industrial. No presente estudo, as CDs foram produzidas a partir de diferentes fontes de carbono pelo micro-organismo Bacillus circulans ATCC 21783, estudou-se seu crescimento celular assim como sua produção enzimática, utilizando a ferramenta estatística de planejamento experimental. O micro-organismo Bacillus circulans ATCC 21783 mostrou-se ser eficiente na produção da enzima CGTase, os resultados indicaram a potencialidade do grão de sorgo como o melhor substrato para fermentação na produção de CGTase. Quanto maior o tamanho do grão de sorgo, maiores concentrações de glicose e amido estarão presentes, o que influencia diretamente a produção enzimática. Por meio do planejamento experimental foram proposto modelos matemáticos que expressam tanto a produção enzimática quanto a concentração das variáveis das concentrações da fonte de carbono, pH e a temperatura. A importância de desenvolver o modelo é demonstrar a sua aplicação bem-sucedida para determinação das condições ideais que representam o processo de alta produtividade enzimática da CGTase. A otimização das variáveis foram obtidas a partir de quatro planejamentos experimentais composto central (PCC) e seus resultados analisados pelas superfícies de resposta. Os melhores resultados do planejamento encontrados no...

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Prostate cancer is the second leading cause of cancer death in the country. Due to this factor, the interest of showing what relationship exists between vasectomy surgery and the incidence of prostate carcinoma has started. Some epidemiological studies showed an increased risk of prostate cancer in vasectomized men (Emard et al., 2001). On the other hand other authors have argued that there is no correlation (Patel et al., 2005) and there are those who said that vasectomy is linked to reduced risk of prostate cancer (Ross, 1983). Faced with an analysis of published works, such discussion remains today. The vasectomy, or deferentectomia, is a contraceptive male method, which is the section of the vas deferens of man by preventing the sperm from being expelled along with the seminal fluid during ejaculation, and is one of the most simple, economical, uncomplicated post- operative. This study aims to evaluate the process of cell proliferation and to evaluate immuno-histochemically the expression of specific markers of PCNA (Proliferating Cell Nuclear Antigen) and Ki-67, in the prostate of the gerbil after chemical induction by intraperitoneal injection of the carcinogen N-methyl -N-nitrosourea (MNU), because the regulation of the functional balance between cell proliferation and apoptosis is associated with hyperplasia and prostatic carcinoma. The experimental procedure was performed at the Laboratory of the Department of Anatomy, along with collecting the data for later analysis

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It is believed that epigenetic mechanisms such as DNA methylation are important for the tumorigenesis and maintenance of the altered state of tumor cells. DNA methylation occurs by the addition of a methyl group to carbon 5 of cytosine, catalyzed by the enzyme DNA methyl-transferase, which can change the expression of a gene, including the tumor suppressor genes. In human squamous cell carcinoma, several features have shown the etiological role of genes in tumor development. Among them, FOXE1 gene (forkhead box E1 - thyroid transcription factor) is presented with an important role in susceptibility to disease. Similarly the FOXE1 methylation pattern could alter the expression of this gene in dogs and predisposed to tumor on. Therefore, this study aims to investigate in dogs, the validity of the strategy employed in humans to analyze the FOXE1 methylation status. DNA extraction from fresh frozen tumoral samples was performed by Wizard Genomic® DNA Purification Kit. The methylation status was determined by MSP-PCR (methylation-specific polymerase chain reaction), using 2.0 ng of DNA treated with sodium bisulphate. One hundred micrograms of bisulphite-modified DNA was amplified using primers specific for either methylated or unmethylated DNA (primers sequences are available at http://pathology2.jhu.edu/pancreas/primer.pdf). The analysis of fragments was loaded on to 7% polyacrylamide gels and silver nitrate staining. In this stage of technical approach, 60% were FOXE1 hypermethylated. In conclusion, it was observed that the standard technique for assessing the methylation pattern of gene FOXE1 in humans can be used for the same evaluation in dogs. The correlation of these molecular data with clinical and histopathological parameters may have diagnostic and prognostic value and still be used as a tumor marker for therapeutic decision and surgical approach

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Sickle cell anemia (SCA) shows a pathophysiology that involves multiple changes in sickle cell erythrocytes, vaso-occlusive episodes, hemolysis, activation of inflammatory mediators, endothelial cell dysfunction, and oxidative stress. These events complicate treatment and culminate in the development of manifestations such as anemia, pain crises and multiorgan dysfunction. The aim of this study was to evaluate, in SCA patients, oxidative stress and antioxidant capacity markers, correlating them to treatment with hydroxyurea (HU), β-globin haplotypes and glutathione S-transferase polymorphisms (GSTT1, GSTM1 and GSTP1), in comparison to a control group (CG). The study groups were composed of 48 individuals without hemoglobinopathies (CG), SCA patients treated with HU [AF (+HU), N = 13] and untreated SCA patients [AF (-HU), N = 15], after informed consent. The groups were analyzed using cytological, electrophoretic, chromatographic and molecular methods and information from medical records. The GSTM1 and GSTT1 polymorphisms were determined by multiplex PCR, while the GSTP1 polymorphism by PCR-RFLP. Biochemical parameters were measured using spectrophotometric methods [TBARS, TEAC and catalase (CAT) and GST activities] and a chromatographic method [glutathione (GSH)]. The fetal Hb (Hb F) levels observed in the SCA (+HU) group (10.9%) confirmed the already well-described pharmacological effect of HU, but the SCA (-HU) group also had high Hb F levels (6.1%), which may have been influenced by genetic factors not targeted in this study. We found a higher frequency of the Bantu haplotype (48.2%), followed by the Benin (32.1%) and also Cameroon haplotypes, rare in our population, and 19.7% of atypical haplotypes. The presence of Bantu haplotype was related to higher lipid peroxidation levels in patients, but also, it conferred a differential response to HU treatment, raising Hb F levels in 52.6% (P = 0.03). The protective effect of Hb F was confirmed, because the increase in their levels resulted in a 41.3% decrease in lipid peroxidation levels (r = -0.74, P = 0.0156). The genotypic frequency of the GST polymorphisms observed was similar to that of other studies in the Brazilian population, and its association with biochemical markers revealed a significant difference only for the GSTP1 polymorphism, where patients with genotype V/V showed higher GSH and TEAC levels (P = 0.04 and P = 0.03, respectively) compared to patients with genotype I/I. The TBARS levels were about five to eight times higher in the SCA (+HU) and SCA (-HU) groups, respectively, compared to controls, and HU produced a 35.2% decrease in lipid peroxidation levels in the SCA (+HU) group (P < 0.0001). Moreover, the SCA (+HU) group showed higher TEAC levels when compared to CG (P = 0.002). We did not find any significant difference in GST activity between the groups studied (P = 0.76), but CAT activity was about 17 and 30% lower in SCA (+HU) and SCA (-HU) groups, respectively (P < 0.00001). Plasma GSH levels were ~2 times higher in SCA patients than in the control group (P = 0.0005) and showed a positive correlation with TBARS levels, confirming its antioxidant function. HU treatment contributed to higher CAT activity and TEAC levels and lower lipid peroxidation, and its pharmacological effect showed a “haplotype-dependent” response. These findings may contribute to elucidating the potential of HU in ameliorating oxidative stress in SCA subjects.

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