Agency: European Commission | Branch: FP7 | Program: CP-SICA | Phase: HEALTH-2007-2.3.4-1 | Award Amount: 3.75M | Year: 2009
The focus of this multidisciplinary proposal is to elucidate the epidemiology of the genetic lineages of T. cruzi, for improved understanding and prevention of Chagas disease. The project will unite skills in genotyping, genomics, genetics and pathogenesis in Europe with considerable compatible skills in South America, and with key research in endemic areas that have distinct characteristics. The proposal is intended to be high impact in terms of both research progress and fostering of collaborative networks. Aim: Elucidate the epidemiology of the genetic lineages of T. cruzi, for improved understanding and prevention of Chagas disease. Technology development: 1. Develop further and apply MLST; PCR-RFLP and MLMT to the analysis of genetic populations of T. cruzi, 2. Sequence the unresolved genome of T. cruzi I, 3. Develop lineage specific diagnosis, 4. Develop an oligochromatography PCR-dipstick procedure for detection of T. cruzi. Molecular epidemiology: 5. Pilot studies of association between genetic lineage, clinical outcome, and prevalence of congenital infection, 6. Map the silvatic vector, silvatic mammal, human and ecological associations of the T. cruzi genotypes IId,e,b,a. 7. Compare lineage specific pathogenesis and transmissibility of congenital infection in a mouse model, and compare lineage susceptibility to drugs in vitro. Population genetics and phylogenetics: 8. Re-evaluate the population genetics and evolution of T. cruzi lineages. International cryobank and database: 9. Establish in South America an accessible, expanded, international cryobank for T. cruzi, 10. Establish a website and database for outputs of the project. The project encompasses the desirable characteristics prescribed by the call, in that they include: genomics/proteomics; effective, innovative relevance to disease, pathogenesis, drugs, interventions; an integrated multidisciplinarity, and capacity building, networking and training in endemic regions.
Agency: European Commission | Branch: FP7 | Program: CP-FP-SICA | Phase: SiS-2009-126.96.36.199 | Award Amount: 1.20M | Year: 2010
A number of findings from research in science education are well known and broadly accepted. They refer e.g. to inquiry based, learning by doing, social dimension of learning, active learning, diversity of learning styles, based on individual, cultural, ethnic, gender-related factors. For researchers working side by side with school teachers, it is everyday experience to see how difficult it is to receive indications coming from research and transform them into teaching practice: there are cultural barriers, preparation barriers, time and resource constraints. TRACES will promote transformative research activities and investigate the factors that contribute to the research-practice gap and identify innovative policies in science education that can contribute to fill that gap. It will do so through both desk and field research, in a cyclic process of analysis, action, reflection. In particular, we are interested in looking at the effectiveness of research based science teaching in taking account of learners diversities in terms on individual, cultural, ethnic, linguistic, gender-related factors.
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.
Sabate D.C.,National University of Salta |
Audisio M.C.,National University of Salta
Microbiological Research | Year: 2013
Three surfactin-producing Bacillus subtilis strains, C4, M1 and G2III, previously isolated from honey and intestines from the Apis mellifera L. bee, were phylogenetically characterized at sub-species level as B. subtilis subsp. subtilis using gyrA gene sequencing. The antagonistic effect of surfactin was studied against seven different Listeria monocytogenes strains, 6 of which were resistant to bacteriocins. Surfactin showed anti- Listeria activity against all 7 strains and a dose of 0.125. mg/mL of surfactin was enough to inhibit this pathogen. Surfactin sintetized by B. subtilis subsp. subtilis C4 inhibited the pathogen in lower concentrations, 0.125. mg/mL, followed by G2III and M1 with 0.25 and 1. mg/mL, respectively. In particular, a dose of 0.125. mg/mL reduced the viability of L. monocytogenes 99/287 RB6, a bacteriocin-resistant strain, to 5 log orders. Surfactin assayed maintained anti- Listeria activity within a pH range of between 2 and 10, after heat treatment (boiling for 10. min and autoclaving at 121 °C for 15. min) and after treatment with proteolytic enzymes. These results suggest that surfactin can be used as a new tool for prevention and the control of L. monocytogenes in different environments, for example, in the food industry. © 2012 Elsevier GmbH.
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.
Slavutsky A.M.,National University of Salta |
Bertuzzi M.A.,National University of Salta
LWT - Food Science and Technology | Year: 2015
Nanolaminated films were formulated by coating a hydrophilic film with a lipid nanolayer. This was performed by coating a starch film with sunflower oil, due to favourable interfacial forces that interact between the oil and the starch film support. The lipid nanolayer presence was corroborated by SEM analyses. Sorption isotherm curves of nanolaminated films show the same trend as starch films used as support but with an important reduction in the film water content through all the aw range studied. The effect on permeability and diffusivity of the driving force (δaw) and aw range, were evaluated. Water diffusion coefficients of oil laminated films are lower than the corresponding to starch films and in both cases, diffusivity decreases with aw. Water vapour permeability depends on the driving force and aw range, and it was concluded that in nanolaminated films, permeation phenomenon is controlled by water diffusion through the hydrophobic nanolayer. Nanolaminated films show an increase in tensile strength and Young module with a decrease in elongation in relation to starch based films. © 2014 Elsevier Ltd.
Slavutsky A.M.,National University of Salta |
Bertuzzi M.A.,National University of Salta
Carbohydrate Polymers | Year: 2014
Water transport in edible films based on hydrophilic materials such as starch, is a complex phenomenon due to the strong interaction of sorbed water molecules with the polymeric structure. Cellulose nanocrystals (CNC) were obtained from sugarcane bagasse. Starch and starch/CNC films were formulated and their water barrier properties were studied. The measured film solubility, contact angle, and water sorption isotherm indicated that reinforced starch/CNC films have a lower affinity to water molecules than starch films. The effects that the driving force and the water activity (aw) values at each side of the film have on permeability were analyzed. Permeability, diffusivity, and solubility coefficients indicated that the permeation process depends mostly on the tortuous pathway formed by the incorporation of CNC and therefore were mainly controlled by water diffusion. The interaction between CNC and starch chain is favoured by the chemical similarities of both molecules. © 2014 Elsevier Ltd.
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.
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.
Salazar G.A.,National University of Salta
Atmospheric Environment | Year: 2011
For ten sites in Argentina, monthly average Ångström turbidity coefficient β values were estimated using mean monthly global solar irradiation values measured at these sites from the former Argentinean radiometric network REDSOL. The values of the horizontal direct and diffuse components of the global irradiation were estimated using the Yang Hybrid model (YHM) and, to determine the representativeness of those results, they were compared to values from the SWERA database which uses the CSR model, developed by NREL, to make estimates. An inconsistency in the estimated values of the diffuse component was detected, therefore a new expression for that component was proposed, generating a corrected version of the YHM (CYHM). The turbidity coefficient β is considered an independent variable in the equation that estimates the direct transmittance and the values that forces an exact correlation between the measured monthly average global irradiance values with those estimated with the CYHM are considered representative for each site since the RMSE between the monthly global irradiation values of SWERA and CYHM is 11.7%, this value being very close to that found by the designers of the CSR model (10%) when they tested it with meteorological data from USA. The monthly average value estimates of turbidity coefficient β show expected behavior, with values varying according to the season of the year. © 2011 Elsevier Ltd.