73 research outputs found

    β-thalassemia Intermedia In A Brazilian Patient With - 101 (c > T) And Codon 39 (c > T) Mutations

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    Context: We verified molecular alterations in a 72-year-old Brazilian male patient with a clinical course of homozygous β-thalassemia intermedia, who had undergone splenectomy and was surviving without regular blood transfusions. The blood cell count revealed microcytic and hypochromic anemia (hemoglobin = 6.5 g/dl, mean cell volume = 74 ft, mean cell hemoglobin = 24 pg) and hemoglobin electrophoresis showed fetal hemoglobin = 1.3%, hemoglobin A 2 = 6.78% and hemoglobin A = 79.4%. Objective: To identify mutations in a patient with the symptoms of β-thalassemia intermedia. Design: Molecular inquiry into the mutations possibly responsible for the clinical picture described. Setting: The structural molecular biology and genetic engineering center of the Universidade Estadual de Campinas, Campinas, Brazil. Procedures: DNA extraction was performed on the patient's blood samples. The polymerase chain reaction (PCR) was done using five specific primers that amplified exons and the promoter region of the β globin gene. The samples were sequenced and then analyzed via computer programs. Results: Two mutations that cause the disease were found: -101 (C > T) and codon 39 (C > T). Conclusions: This cases represents the first description of -101 (C > T) mutation in a Brazilian population and it is associated with a benign clinical course.12112830Baysal, E., Carver, M.F.H., The beta and delta-thalassemia repository (1995) Hemoglobin., 19 (3-4), pp. 213-236Zago, M.A., Costa, F., Bottura, C., Beta-thalassemia in Brazil (1981) Braz. J. Med. Biol. Res., 14 (6), pp. 383-388Ewing, B., Green, P., Base-calling of automated sequencer traces using Phred. II Error probabilities (1998) Genome Res., 8 (3), pp. 186-194Green, P., (2002), http://bozeman.genome.washington.edu/phrap.docs/phrap.html, The Phred/Phrap/Consed System Home Page. Phrap Assembler. Available at URL September 30Gordon, D., Abajian, C., Green, P., Consed: A graphical tool for sequence finishing (1998) Genome Res., 8 (3), pp. 195-20

    Cytogenetic characterization and evaluation of c-MYC gene amplification in PG100, a new Brazilian gastric cancer cell line

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    Gastric cancer is the fourth most frequent type of cancer and the second cause of cancer mortality worldwide. The genetic alterations described so far for gastric carcinomas include amplifications and mutations of the c-ERBB2, KRAS, MET, TP53, and c-MYC genes. Chromosomal instability described for gastric cancer includes gains and losses of whole chromosomes or parts of them and these events might lead to oncogene overexpression, showing the need for a better understanding of the cytogenetic aspects of this neoplasia. Very few gastric carcinoma cell lines have been isolated. The establishment and characterization of the biological properties of gastric cancer cell lines is a powerful tool to gather information about the evolution of this malignancy, and also to test new therapeutic approaches. The present study characterized cytogenetically PG-100, the first commercially available gastric cancer cell line derived from a Brazilian patient who had a gastric adenocarcinoma, using GTG banding and fluorescent in situ hybridization to determine MYC amplification. Twenty metaphases were karyotyped; 19 (95%) of them presented chromosome 8 trisomy, where the MYC gene is located, and 17 (85%) presented a deletion in the 17p region, where the TP53 is located. These are common findings for gastric carcinomas, validating PG100 as an experimental model for this neoplasia. Eighty-six percent of 200 cells analyzed by fluorescent in situ hybridization presented MYC overexpression. Less frequent findings, such as 5p deletions and trisomy 16, open new perspectives for the study of this tumor.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal do Pará Instituto de Ciências Biológicas Laboratório de Citogenética HumanaUniversidade Federal de São Paulo (UNIFESP) Disciplina de GenéticaUNIFESP, Disciplina de GenéticaCNPq: 20/2007CNPq: 550885/2007-2SciEL

    Critical aspects of the random-field Ising model

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    We investigate the critical behavior of the three-dimensional random-field Ising model (RFIM) with a Gaussian field distribution at zero temperature. By implementing a computational approach that maps the ground-state of the RFIM to the maximum-flow optimization problem of a network, we simulate large ensembles of disorder realizations of the model for a broad range of values of the disorder strength h and system sizes  = L3, with L ≤ 156. Our averaging procedure outcomes previous studies of the model, increasing the sampling of ground states by a factor of 103. Using well-established finite-size scaling schemes, the fourth-order’s Binder cumulant, and the sample-to-sample fluctuations of various thermodynamic quantities, we provide high-accuracy estimates for the critical field hc, as well as the critical exponents ν, β/ν, and γ̅/ν of the correlation length, order parameter, and disconnected susceptibility, respectively. Moreover, using properly defined noise to signal ratios, we depict the variation of the self-averaging property of the model, by crossing the phase boundary into the ordered phase. Finally, we discuss the controversial issue of the specific heat based on a scaling analysis of the bond energy, providing evidence that its critical exponent α ≈ 0−
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