Papers by JOSE IGNACIO DELGADO BARRA
Genetics, 1996
Intense biochemical and genetic research on the eth-1 r mutant of Neurospora crassa suggested th... more Intense biochemical and genetic research on the eth-1 r mutant of Neurospora crassa suggested that this locus might encode S-adenosylmethionine synthetase (S-Adomet synthetase). We have used protoplast transformation and phenotypic rescue of a thermosensitive phenotype associated with the eth-1 r mutation to clone the locus. Nucleotide sequence analysis demonstrated that it encodes S-Adomet synthetase. Homology analyses of prokaryotic, fungal and higher eukaryotic S-Adomet synthetase polypeptide sequences show a remarkable evolutionary conservation of the enzyme. N. crassa strains carrying S-Adomet synthetase coding sequences fused to a strong heterologous promoter were constructed to assess the phenotypic consequences of in vivo S-Adomet synthetase overexpression. Studies of growth rates and microscopic examination of vegetative development revealed that normal growth and morphogenesis take place in N. crassa even at abnormally high levels of cellular S-Adomet. The degree of cyto...
Genetics, 1996
eth-1r a thermosensitive allele of the Neurospora crassa S-adenosylmethionine (AdoMet) synthetase... more eth-1r a thermosensitive allele of the Neurospora crassa S-adenosylmethionine (AdoMet) synthetase gene that confers ethionine resistance, has been cloned and sequenced. Replacement of an aspartic amino acid residue (D48 → N48), perfectly conserved in prokaryotic, fungal and higher eukaryotic AdoMet synthetases, was found responsible for both thermosensitivity and ethionine resistance conferred by eth-1r. Gene fusion constructs, designed to overexpress eth-1r in vivo, render transformant cells resistant to ethionine. Dominance of ethionine resistance was further demonstrated in eth-1 +/eth-1r partial diploids carrying identical gene doses of both alleles. Heterozygous eth-1 +/eth-1r cells have, at the same time, both the thermotolerance conferred by eth-1 + and the ethionine-resistant phenotype conferred by eth-1r. AdoMet levels and AdoMet synthetase activities were dramatically decreased in heterozygous eth-1 +/eth-1r cells. We propose that this negative effect exerted by eth-1r...
American Journal of Physiology-Gastrointestinal and Liver Physiology, 1984
The interaction of biologically active 125I-labeled cholera toxin with isolated chick intestinal ... more The interaction of biologically active 125I-labeled cholera toxin with isolated chick intestinal epithelial cells involves a large number (approx 1.7 10(6)/cell) of high-affinity (Kd = 8–9 X 10(-9) M) binding sites that belong to a single class. Binding of iodotoxin to the cells occurs rapidly, is half-maximal within 1 min, and is complete in 3–7 min (at 37 degrees C) depending on the toxin concentration. Toxin binding is saturable and includes only a small contribution from nonspecific sites. Ligand competition studies suggest that the isolated B subunit of choleragen (CT-B) behaves in an almost identical fashion to the holotoxin (CT), whereas the A subunit shows no detectable activity in competitive binding. Assays for cAMP indicate that neither that A nor the B subunits of CT contain any activity for increasing the level of intracellular cAMP. B subunit, when incubated with CT, inhibits CT-induced elevation of cAMP in a dose-dependent manner. Preincubation of 125I-CT with various...
Agradeço a Deus, comandante a nos direcionar nesta viagem do saber e do conhecimento, pela vida. ... more Agradeço a Deus, comandante a nos direcionar nesta viagem do saber e do conhecimento, pela vida. Agradeço imensamente à minha esposa Gislane Damasceno, que compreende bem a importância da formação e, por isso, fez de tudo para me ajudar nessa conquista. Ela, que é também, de muitas formas, autora deste trabalho, foi e sempre será meu amor, meu incentivo e meu suporte. Aos meus filhos Luciano, Gabriela e Giuliano, por terem, em vários momentos, de abrir mão da presença paterna sem compreender o porquê das viagens semanais. Luciano, que assumiu o papel de pai, teve de se desdobrar entre a dinâmica da vida de criança, os afazeres do lar e os estudos. Aos meus pais Olvandino e Zeneide e aos meus irmãos Ana Maria, João, Rita, Lúcia, Zé Fernandes, Zé Vando, e Antônio, família de pescadores que aprendeu a vencer na vida a partir de um ensinamento ímpar chamado honestidade. Cada um de seu jeito, de sua maneira sempre esteve ao meu lado; uns mais presentes, dando-me dinheiro pra viagem, pra hospedagem, outros, orgulhosos de ter alguém que ousou acreditar e foi capaz de vencer através da educação. Ao meu orientador Prof. Dr. Gilmar Pereira da Silva, companheiro e amigo que me inspira a viver, de fato, práticas emancipadoras de educação. Vejo nele alguém realmente comprometido em transformar a sociedade por meio da educação. Agradeço à minha sogra Maria de Nazaré e ao meu sogro Jarbas Furtado, pessoas especiais sempre. Ao meu cunhado Raimundo Nunes e à minha irmã Maria Rita, que me acolheram em sua casa durante o período de estudo, abrindo mão de seu espaço para também contribuir para minha conquista, minha eterna gratidão. A todos os meus sobrinhos, representados aqui pelo Genilson "Cibalena", exemplos de lealdade e compromisso, por terem me ajudado imensamente nos momentos das dificuldades, sobretudo, financeiras. Ao Programa de Pós Graduação em Educação da UFPA e a todos os seus docentes, na pessoa da Profa. Marilena Loureiro, que criaram as condições para que eu me tornasse, de fato, um pesquisador. Ao Prof. Dr. Doriedson Rodrigues, exemplo de dedicação e reflexo de comprometimento e engajamento do fazer docente, cuja história de vida muito se assemelha à minha e, nessa relação, me ensina a percorrer o caminho da prática docente de forma corajosa e afetuosa. À Colônia de Pescadores Z-16 de Cametá, onde trabalhei durante vários anos e onde milito até hoje, por ter me ensinado que as conquistas vêm pela persistência e pelo trabalho, pois, com apenas alguns sócios e um prédio simples, essa entidade conseguiu se tornar referência de organização e de luta social. Às muitas pessoas e instituições que possibilitaram a realização deste trabalho de pesquisa, que considero, pessoalmente, resultado de um grande esforço coletivo! A todos, obrigado pelo estímulo, pelas opiniões, pelos textos enviados, pelos comentários compartilhados, pelas críticas, pelas conversas e, também, pelos momentos de descanso e renovação da alma para continuar trilhando esse caminho difícil, mas prazeroso. Palavras-chave: Pesca artesanal. Movimentos sociais. Acordos de pesca. Colônia de pescadores.
En general, el derecho al ser pragmatico adquiere especial importancia el formalismo (llamado tam... more En general, el derecho al ser pragmatico adquiere especial importancia el formalismo (llamado tambien positivismo por la doctrina juridica) pero estas ideas actuan como principios orientadores de los contratos, lo cual significa que sirven para dar curso a argumentaciones teorico-filosoficas que en ningun caso pretenden llegar a ser excluyentes el uno del otro. Los principios sirven para corregir las desviaciones de las instituciones frente a casos extremos, por lo tanto, hay que atender a circunstancias especiales para ver cual de ellos pesa mas. Este es el tema central que pretendo explicar en el presente trabajo de investigacion y para ello sera necesario analizar a los distintos autores que se enmarcan dentro de una determinada corriente para luego centrarme en que para lograr explicar la obligatoriedad del contrato es fundamental complementar estos principios y no considerar que son excluyentes. Asi, de esta forma, se podra tener una vision mas acabada de esta institucion juridica que es la base del derecho civil, mas todavia, del derecho en general.
The Mckinsey Quarterly, Sep 22, 2001
Family-owned businesses in Latin America need stronger governance structures to survive and thriv... more Family-owned businesses in Latin America need stronger governance structures to survive and thrive in an era of globalization. The backbone of the economies of Latin America, and of most emerging markets, has traditionally been family-owned businesses, whether they be huge conglomerates or corner bodegas. In more developed economies, stock markets tend to view family-owned businesses [1] with suspicion: when family members aren't squabbling, it is thought, they are looking after their own interests rather than those of the business. Empirical evidence suggests that there is some truth to the common observation that the first generation builds the company, the second preserves it, and the third squanders it. In fact, fewer than 15 percent of family-owned businesses survive under family control beyond the third generation. But family-owned businesses have their purposes, especially in areas that lack developed capital markets and a cadre of professional managers: if successful, they provide investors in emerging markets with an alternative to holding illiquid or volatile shares in opaque public companies. Last year, the market capitalization of Latin America's stock exchanges represented only 32 percent of gross domestic product, while the corresponding figure in Southeast Asia was 114 percent of GDP; in Europe, 115 percent; and in the United States, 164 percent (Exhibit 1). Nevertheless, the representation of family-owned businesses in the ranks of the top 100 companies has fallen sharply--from 70.8 percent (1994) to 57.1 percent (1999) in Mexico and from 24 percent to 18.8 percent in Argentina--as deregulation and the advent of multinational corporations have spurred the cross-border integration of economies and industries. And many family-owned businesses cannot match the multinationals' scale, strategic focus, cutting-edge management techniques, and deep pockets (Exhibit 2). To survive and thrive, big family-owned businesses in Latin America must shift to strategies that will enable them to compete more successfully. To execute any high-performance strategy, they first need stronger governance models that can prevent family squabbles from spilling over into the business, help it obtain the strongest management talent, and provide for a smooth succession of power across generations. Diversified growth Family-owned businesses in Latin America have traditionally held interests in a range of industries. Although this approach often strained the management and capital resources of these businesses, the fact is that protectionist trade, investment, and, sometimes, foreign-exchange restrictions often made local diversification the only way to grow. Many family-owned Latin American business conglomerates, grupos such as the enterprises controlled by the Santo Domingo family, in Colombia (airlines, automobiles, beer, the mass media, telecommunications), thrived in these closed economies, becoming dominant forces in several industries. Many of the attributes of family-owned businesses have accounted for their relative success in the region. Their informal structure, for example, facilitates quick decision making, which is vital in a region plagued by political and economic instability. They tend to have strong shared values--often rooted in a founder's vision--and traditions that help to promote staff loyalty. They also tend to have a deep understanding of the peculiarities of their local markets and close ties with high government officials. But the game has changed as Latin American markets have opened up to competition from multinational companies. Some diversified local competitors have found that they are simply no match for foreign focused attackers that have strong management skills, easy access to the capital they need, and the ability to offer better products and services at a lower price. Consequently, Latin American companies risk either going out of business altogether or becoming targets for takeover. …
Pasos De Arte Y Cultura, 2007
Medicina Oral Patologia Oral Y Cirugia Bucal, 2014
Objetivos: El objetivo de este trabajo fue evaluar los habitos de riesgo, fenotipos clinicos y ce... more Objetivos: El objetivo de este trabajo fue evaluar los habitos de riesgo, fenotipos clinicos y celulares y los cambios en ADN TP53 en muestras de mucosa oral de pacientes con Desordenes Orales Potencialmente Malignos (DOPM), con el fin de crear modelos que permitan obtener patrones genotipicos y fenotipicos que determinen el riesgo de que las lesiones malignicen. Diseno del estudio: se recogieron en historias clinicas los fenotipos clinicos, historia familiar de cancer y habitos de riesgo. Se estudio la mutacion del gen TP53 y las caracteristicas morfometricas-morfologicas y se aplicaron modelos multivariantes. Fueron establecidos tres grupos: a) grupo cancer oral (CO) (n=10), b) grupo DOPM (n=10), y c) grupo control (n=8). Resultados: en el 50% de los pacientes con malignizacion se encontraron habitos enolicos y tabaquicos. Se observo un alto porcentaje de mutaciones de TP53 en lesiones de CO (30%) y DOPM (media 20%) (p=0.000). La mayoria de esas mutaciones fueron GC-> TA mutacion translocacion (60%). Sin embargo, los pacientes con CO presentaron mutaciones en todos los exones e intrones estudiados. La mayor precision diagnostica (p=0.0001) fue observada al incorporar las variables de habitos tabaquico y enolico con mutaciones TP53. Conclusiones: Nuestros resultados muestran ser estadisticamente fiables, con estimaciones imparciales de los parametros, incluso para pequenas muestras. Los modelos 2 y 3 fueron los mas precisos para evaluar el riesgo de que DOPM se conviertan en cancerosos. Sin embargo, en un contexto de salud publica, el modelo 3 es el mas recomendado debido a que las caracteristicas consideradas son mas faciles y menos costosas de evaluar.
Religiosidad Popular En Espana Actas Del Simposium 1 4 Ix 1997 Vol 1 1997 Constituciones Sinodales Etc Isbn 84 921074 8 0 Pags 1101 1120, 1997
Acta odontológica latinoamericana : AOL, 2006
The present study evaluates the phenotypic and genotypic changes that take place during early onc... more The present study evaluates the phenotypic and genotypic changes that take place during early oncogenesis. The submandibular glands of male rats were injected with a 0.5% solution of 9,10-dimethyl-1,2-benzanthracene (DMBA) in acetone. Gland samples were taken at 0, 7, 30 and 150 days post-injection and submitted to histological, biochemical, immunocytochemical and PCR evaluation. Histopathological analysis was performed on hematoxylin-eosin stained slides. Total protein content was assessed by Lowry's method and the protein profile was analyzed by 12% SDS-PAGE. Bcl-2 was demonstrated by silver-enhanced gold immunolabeling. p53 immunolabeling was performed using the streptavidin-biotin system. All the treated animals developed carcinoma-like lesions at 30 and 150 days. Total protein concentration rose significantly (p < 0.05) above control values at 7, 30 and 150 days. The treated glands exhibited positive immunolabeling for p53 in the nuclei of neoplastic cells at 30 and 150 ...
Mutation research, 2008
Escherichia colidam cells have an active but non-directed mismatch repair system; therefore, asse... more Escherichia colidam cells have an active but non-directed mismatch repair system; therefore, assembly of MutSLH complex at a mismatched base pair can result in MutH-mediated cleavage of GATC sites in both DNA strands. Unpaired double-strand breaks on a fraction of the replication errors occurring in dam cells presumably cause cell death, selectively eliminating these putative mutants from the population. We show that E. colidam cells transformed with plasmids containing either the mutS, mutL or mutH gene display a mutation frequency three to eight times lower than that of the parental dam strain, due to increased mismatch-stimulated cell killing. Transformed strains are also more susceptible to killing by the base analogue 2-aminopurine. However, dam and dam transformed cells have similar duplication time, proportion of live/dead cells and morphology.
Se trata de probar la relación entre sintomatología ansiosa y el modo de aculturación que adopta ... more Se trata de probar la relación entre sintomatología ansiosa y el modo de aculturación que adopta la población inmigrante. Para ello, se ha tomado una muestra de 43 sujetos inmigrantes de la provincia de Sevilla, seleccionada de modo incidental en distintas asociaciones de inmigrantes. Dos grupos componen la muestra: marroquí (17 individuos) y latinoamericana (26 individuos). La información necesaria para llevar a cabo el estudio se ha obtenido mediante la realización de entrevistas personalizadas en las que se han administrado dos cuestionarios, el Cuestionario de Ansiedad Estado-Rasgo (STAI) de Spielberger, Gorsuch y Lushene (1988) y el Cuestionario sobre Modos de Aculturación de Navas y cols. (2004). Los resultados obtenidos indican que no existe una relación significativa entre las variables ansiedad (estado y rasgo) y modos de aculturación; sin embargo, sí puede observarse un ligero incremento de la ansiedad estado en la población de origen marroquí. Palabras clave: modos de aculturación, inmigración, ansiedad.
Protein Expression and Purification, 2008
The B subunit of Escherichia coli heat-labile toxin (LTB) may function as an efficient carrier mo... more The B subunit of Escherichia coli heat-labile toxin (LTB) may function as an efficient carrier molecule for the delivery of genetically coupled antigens across the mucosal barrier. We constructed vectors for the expression of LTB and LTBSC proteins. LTBSC is a fusion protein that comprises the amino acid sequence from the C-domain of rat synapsin fused to the C-terminal end of LTB. Both constructions have a coding sequence for a 6His-tag fused in-frame. LTBSC was expressed in E. coli as inclusion bodies. The inclusion bodies were isolated and purified by Ni2+-chelating affinity chromatography under denaturing condition. Purified LTBSC was diluted in several refolding buffers to gain a soluble and biologically active protein. Refolded LTBSC assembled as an active oligomer which binds to the GM1 receptor in an enzyme-linked immunosorbent assay (ELISA). Soluble LTB in the E. coli lysate was also purified by Ni2+-chelating affinity chromatography and the assembled pentamer was able to bind with high affinity to GM1 in vitro. LTBSC and LTB were fed to rats and the ability to induce antigen-specific tolerance was tested. LTBSC inhibited the specific delayed-type hypersensitivity (DTH) response and induced decreased antigen-specific in vivo and in vitro cell proliferation more efficiently than LTB. Thus, the novel hybrid molecule LTBSC when orally delivered was able to elicit a systemic immune response. These results suggest that LTBSC could be suitable for exploring further therapeutic treatment of autoimmune inflammatory diseases involving antigens from central nervous system.
PLoS ONE, 2013
Mismatch Repair System corrects mutations arising from DNA replication that escape from DNA polym... more Mismatch Repair System corrects mutations arising from DNA replication that escape from DNA polymerase proofreading activity. This system consists of three main proteins, MutS-L-H, responsible for lesion recognition and repair. MutL is a member of GHKL ATPase family and its ATPase cycle has been proposed to modulate MutL activity during the repair process. Pseudomonas aeruginosa MutL (PaMutL) contains an N-terminal (NTD) ATPase domain connected by a linker to a Cterminal (CTD) dimerization domain that possesses metal ion-dependent endonuclease activity. With the aim to identify characteristics that allow the PaMutL NTD allosteric control of CTD endonuclease activity, we used an in silico and experimental approach to determine the interaction surfaces of P. aeruginosa NTD (PaNTD), and compared it with the well characterized Escherichia coli MutL NTD (EcNTD). Molecular dynamics simulations of PaNTD and EcNTD bound to or free of adenosine nucleotides showed that a significant difference exists between the behavior of the EcNTD and PaNTD dimerization interface, particularly in the ATP lid. Structure based simulations of MutL homologues with endonuclease activity were performed that allowed an insight of the dimerization interface behavior in this family of proteins. Our experimental results show that, unlike EcNTD, PaNTD is dimeric in presence of ADP. Simulations in mixed solvent allowed us to identify the PaNTD putative DNA binding patch and a putative interaction patch located opposite to the dimerization face. Structure based simulations of PaNTD dimer in presence of ADP or ATP suggest that nucleotide binding could differentially modulate PaNTD protein-protein interactions. Far western assays performed in presence of ADP or ATP are in agreement with our in silico analysis.
PLoS ONE, 2012
Different studies have suggested that mutation rate varies at different positions in the genome. ... more Different studies have suggested that mutation rate varies at different positions in the genome. In this work we analyzed if the chromosomal context and/or the presence of GATC sites can affect the frameshift mutation rate in the Escherichia coli genome. We show that in a mismatch repair deficient background, a condition where the mutation rate reflects the fidelity of the DNA polymerization process, the frameshift mutation rate could vary up to four times among different chromosomal contexts. Furthermore, the mismatch repair efficiency could vary up to eight times when compared at different chromosomal locations, indicating that detection and/or repair of frameshift events also depends on the chromosomal context. Also, GATC sequences have been proved to be essential for the correct functioning of the E. coli mismatch repair system. Using bacteriophage heteroduplexes molecules it has been shown that GATC influence the mismatch repair efficiency in a distance-and number-dependent manner, being almost nonfunctional when GATC sequences are located at 1 kb or more from the mutation site. Interestingly, we found that in E. coli genomic DNA the mismatch repair system can efficiently function even if the nearest GATC sequence is located more than 2 kb away from the mutation site. The results presented in this work show that even though frameshift mutations can be efficiently generated and/or repaired anywhere in the genome, these processes can be modulated by the chromosomal context that surrounds the mutation site.
Oral Oncology, 2014
(RDU), es un espacio donde se almacena, organiza, preserva, prov ee acceso libre y procura dar vi... more (RDU), es un espacio donde se almacena, organiza, preserva, prov ee acceso libre y procura dar visibilidad a nivel nacional e internacional, a la producción científica, académica y cultural en formato digital , generada por los integrantes de la comunidad universitaria.
Medicina Oral Patología Oral y Cirugia Bucal, 2013
Objectives: The aim of this work was to assess risk habits, clinical and cellular phenotypes and ... more Objectives: The aim of this work was to assess risk habits, clinical and cellular phenotypes and TP53 DNA changes in oral mucosa samples from patients with Oral Potentially Malignant Disorders (OPMD), in order to create models that enable genotypic and phenotypic patterns to be obtained that determine the risk of lesions becoming malignant. Study Design: Clinical phenotypes, family history of cancer and risk habits were collected in clinical histories. TP53 gene mutation and morphometric-morphological features were studied, and multivariate models were applied. Three groups were estabished: a) oral cancer (OC) group (n=10), b) OPMD group (n=10), and c) control group (n=8). Results: An average of 50% of patients with malignancy were found to have smoking and drinking habits. A high percentage of TP53 mutations were observed in OC (30%) and OPMD (average 20%) lesions (p=0.000). The majority of these mutations were GC → TA transversion mutations (60%). However, patients with OC presented mutations in all the exons and introns studied. Highest diagnostic accuracy (p=0.0001) was observed when incorporating alcohol and tobacco habits variables with TP53 mutations. Conclusions: Our results prove to be statistically reliable, with parameter estimates that are nearly unbiased even for small sample sizes. Models 2 and 3 were the most accurate for assessing the risk of an OPMD becoming cancerous. However, in a public health context, model 3 is the most recommended because the characteristics considered are easier and less costly to evaluate.
Journal of Oral Pathology & Medicine, 2008
BACKGROUND: In recent years, success of statistics in field of genetics has been the identificati... more BACKGROUND: In recent years, success of statistics in field of genetics has been the identification of genes that affect the process of disease. Experimental models using animals enable early stages of tumor development to be studied. The aim of this study was to apply graph models to assess the association between the observed phenotypic changes in rat oral mucosa and induced tumorigenesis in the submandibular gland (SMG). MATERIALS AND METHODS: We studied changes in oncogenes TP53 and bcl-2, histopathological and immunomarker variables in samples of oral mucosa and SMG of Wistar male rats, 60 days old and 180 g in weight, in which tumorigenesis was induced in their SMG by a 0.5% solution of 9,10-dimethyl-1,2-benzanthracene in acetone. A set of linear structural equations were defined, with each formula indicating the response variables and the direct influences. In graph models, saliva was considered as a latent variable. The association was analyzed using Graphical Gaussian Markov models and odd ratios. RESULTS: About 40% of animals treated with 9, 10dimethyl-1, 2-benzanthracene showed histological alterations in the epithelial basal strata of their oral mucosa only at 150 days. Statistical models indicated a relationship between gene alteration in gene bcl-2 in the SMG and histological changes observed in the oral mucosa (P = 0.04). CONCLUSION: Graph statistical model with one latent variable allows to conclude that these results associated with other clinical parameters may be useful in detecting early changes in SMG tumorigenesis. Furthermore, the design of randomized sampling of oral mucosa allows to validate these results and establish a reliable methodology for presumptive diagnosis or screening in the future.
Journal of Bacteriology, 2002
The gene for glycine betaine transmethylase (gbt) was identified in Pseudomonas aeruginosa strain... more The gene for glycine betaine transmethylase (gbt) was identified in Pseudomonas aeruginosa strain Fildes III by biochemical, physiological, and molecular approaches. Based on sequence analysis, the knockout gene corresponded to an open reading frame (ORF) named PA3082 in the genome of P. aeruginosa PAO1. The translated product of this ORF displayed similarity to transferases of different microorganisms. Mutation in gbt blocked the utilization of choline and glycine betaine as carbon and nitrogen sources.
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Papers by JOSE IGNACIO DELGADO BARRA