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Salta, Argentina

The National University of Salta is an Argentine public national university in Salta. It was founded on 11 May 1972 as a part of the Plan Taquini, a reorganization plan for education. It has around 20,000 students. Wikipedia.

Perez Brandan C.,National University of Salta
Bioengineered | Year: 2012

Chagas disease is the clinical manifestation of the infection produced by the parasite Trypanosoma cruzi. Currently there is no vaccine to prevent this disease and the protection attained with vaccines containing non-replicating parasites is limited. Genetically attenuated trypanosomatid parasites can be obtained by deletion of selected genes. Gene deletion takes advantage of the fact that this parasite can undergo homologous recombination between endogenous and foreign DNA sequences artificially introduced in the cells. This approach facilitated the discovery of several unknown gene functions, as well as allowing us to speculate about the potential for genetically attenuated live organisms as experimental immunogens. Vaccination with live attenuated parasites has been used effectively in mice to reduce parasitemia and histological damage, and in dogs, to prevent vector-delivered infection in the field. However, the use of live parasites as immunogens is controversial due to the risk of reversion to a virulent phenotype. Herein, we present our results from experiments on genetic manipulation of two T. cruzi strains to produce parasites with impaired replication and infectivity, and using the mutation of the dhfr-ts gene as a safety device against reversion to virulence. Source

Grossi R.O.,National University of Salta
Acta Mechanica | Year: 2012

This paper deals with the formulation of an analytical model for the dynamic behavior of anisotropic plates, with an arbitrarily located internal line hinge with elastic supports and piecewise smooth boundaries elastically restrained against rotation and translation among other complicating effects. The equations of motion and its associated boundary and transition conditions are derived using Hamilton's principle. By introducing an adequate change of variables, the energies that correspond to the different elastic restraints are handled in a general framework. The concept of transition conditions and the determination of the analytical expressions are presented. Analytical examples are worked out to illustrate the range of applications of the developed analytical model. One of the essential features of this work is to demonstrate how the commonly formal derivations used in the applications of the calculus of variations can be made rigorous. © 2011 Springer-Verlag. Source

Quinteros A.S.,National University of Salta
Zootaxa | Year: 2013

The genus Liolaemus was split in two subgenera, Liolaemus sensu stricto and Eulaemus. Inside the Liolaemus sensu stricto subgenus, many groups have been proposed. One of them is the L. alticolor-bibronii group. Here, I studied 184 morphological characters of more than one thousand specimens that of the L. alticolor-bibronii group. Many of these characters are original from this study, especially the characters related to color pattern. Also, I include eight population without taxonomic status. Using those characters and terminal taxa, I performed phylogenetic analyses using parsimony as optimality criterion, under implied weight. Two difpferent topologies were found. The results show that the L. alticolor-bibronii group is monophyletic, and that it is sister to the L. gravenhorsti group. This finding is congruent with previous morphological and molecular phylogenies. Also, nested within the L. alticolor-bibronii group the L. lemniscatus and the L. robertmentensi groups are found. In contrast to previous hypotheses, Liolaemus tacnae is never recovered as a member of the L. alticolor-bibronii group. Source

Perez Brandan C.,National University of Salta
PLoS neglected tropical diseases | Year: 2011

Trypanosoma cruzi is a protozoan parasite that causes severe disease in millions of habitants of developing countries. Currently there is no vaccine to prevent this disease and the available drugs have the consequences of side effects. Live vaccines are likely to be more effective in inducing protection than recombinant proteins or DNA vaccines; however, safety problems associated to their use have been pointed out. In recent years, increasing knowledge on the molecular genetics of Trypanosomes has allowed the identification and elimination of genes that may be necessary for parasite infectivity and survival. In this sense, targeted deletion or disruption of specific genes in the parasite genome may protect against such reversion to virulent genotypes. By targeted gene disruption we generated monoallelic mutant parasites for the dhfr-ts gene in a T. cruzi strain that has been shown to be naturally attenuated. In comparison to T. cruzi wild type epimastigotes, impairment in growth of dhfr-ts(+/-) mutant parasites was observed and mutant clones displayed decreased virulence in mice. Also, a lower number of T. cruzi-specific CD8(+) T cells, in comparison to those induced by wild type parasites, was detected in mice infected with mutant parasites. However, no remarkable differences in the protective effect of TCC wild type versus TCC mutant parasites were observed. Mice challenged with virulent parasites a year after the original infection with the mutant parasites still displayed a significant control over the secondary infection. This study indicates that it is possible to generate genetically attenuated T. cruzi parasites able to confer protection against further T. cruzi infections. Source

Zimicz N.,National University of Salta
Journal of Mammalian Evolution | Year: 2014

The ecological interaction between small and medium sized South American metatherian carnivores, from the Miocene to Recent, has been analyzed with the objective to understand the ecological interactions between the Hathliacynidae (Sparassodonta) and some Didelphoidea (Didelphimorphia). The species richness through time for these two groups, along with the body mass, diet, and several morphofunctional variables has been analyzed here. The results show a double-wedge geometry of the diversity curve. The climax of the Hathliacynidae took place during the Santacrucian mammal-age with a subsequent decline, in the species richness of this family, followed by the extinction of the family at the Barrancalobian subage. Carnivorous Didelphoidea show a first maximum species richness during the Chapadmalalan followed by a decline and a new rise during Recent times. The coexistence of these mentioned groups took place from the Chasicoan to the Chapadmalalan mammal-ages covering a time span of around 6,000,000 years. The multivariate and univariate analyses of morphofunctional variables suggest a restriction of the Hathliacynidae to hypercarnivory while the Didelphoidea occupied the niche of meso- and hypocarnivory. The body mass analyses show some overlap in small sizes but it is not correlated with any superposition in the morphospace of functional variables. In summary, any passive replacement or active displacement between the Hathliacynidae and carnivorous Didelphoidea are supported by the fossil record. In turn, a partition of the metatherian carnivorous guild seems to have occurred through to the Neogene. The extinction of the Hathliacynidae seems to be a result of environmental change. © 2014, Springer Science+Business Media New York. Source

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