Geographical Distribution of Trypanosoma cruzi Genotypes in Venezuela

Chagas disease is an endemic zoonosis native to the Americas and is caused by the kinetoplastid protozoan parasite Trypanosoma cruzi. The parasite is also highly genetically diverse, with six discrete typing units (DTUs) reported TcI – TcVI. These DTUs broadly correlate with several epidemiogical, ecological and pathological features of Chagas disease. In this manuscript we report the most comprehensive evaluation to date of the genetic diversity of T. cruzi in Venezuela. The dataset includes 778 samples collected and genotyped over the last twelve years from multiple hosts and vectors, including nine wild and domestic mammalian host species, and seven species of triatomine bug, as well as from human sources. Most isolates (732) can be assigned to the TcI clade (94.1%); 24 to the TcIV group (3.1%) and 22 to TcIII (2.8%). Importantly, among the 95 isolates genotyped from human disease cases, 79% belonged to TcI - a DTU common in the Americas, however, 21% belonged to TcIV- a little known genotype previously thought to be rare in humans. Furthermore, were able to assign multiple oral Chagas diseases cases to TcI in the area around the capital, Caracas. We discuss our findings in the context of T. cruzi DTU distributions elsewhere in the Americas, and evaluate the impact they have on the future of Chagas disease control in Venezuela

Trypanosoma cruzi: parasitism in adipose connective tissue

Trypanosoma cruzi, causante de la enfermedad de Chagas, es un hemoflagelado ubicuo e intracelular obligatorio de mamíferos. Macrófagos y adipocitos han sido incriminados como blancos de la invasión temprana por ese parásito; a pesar de ello, su histotropismo es estudiado habitualmente en la musculatura, órganos digestivos y estructuras nerviosas por presentar patología más frecuentemente. En este trabajo se investigó al tejido conectivo graso como un microambiente apropiado para T. cruzi en la fase aguda de la infección, inoculando vía subcutànea a ratones NMRI con aislados caracterizados por RAPD como Zimodeme 1 (Z1=T. cruzi I) obtenidos de Panstrongylus geniculatus; Rhodnius prolixus, Didelphis marsupialis; glándulas anales de estos marsupiales, Rattus rattus y humanos de zonas urbanas y rurales de Venezuela. Animales con parasitemias elevadas (10^5 tripomastigotes/mL de sangre) fueron sacrificados durante la fase aguda de la infección mediante sobreanestesia para retirarles fragmentos de tejido conectivo adiposo univacuolado anexo al esternón, que fueron trabajados histológicamente y teñidos con H-E. Parasitismo intracelular escaso a intenso (1-10/31- 40 pseudoquistes en 50 campos de 400X, respectivamente) con la presencia de estadios amastigotes o tripomastigotes fue producido en macrófagos y adipocitos de ratones. Los resultados muestran que poblaciones de T. cruzi pueden colonizar frecuentemente al conectivo adiposo, independientemente del hospedador experimental y del área geográfica del cual se aislaron; por ello, el estudio de este tejido es recomendado en investigaciones sobre la caracterización de esta parasitosis. Se discuten estos resultados en relación con el hallazgo de T. cruzi en hábitats particulares, como las glándulas anales de marsupiales ricas en lípidos, en las cuales su polimorfismo y metaciclogénesis son dependientes de niveles adecuados de material graso.210 - [email protected]@hotmail.comBimestralTrypanosoma cruzi, an ubiquitous obligatory intracellular hemoflagelate, is responsible for Chagas´s disease in mammals. Macrophages and adipocytes have been considered as to be early parasite invasion targets; even when historically their tissue behavior has usually been studied in muscles and digestive and nervous structures which are generally damaged. In this study connective adipose tissue was investigated as a adequate micro-environment for T. cruzi, during infection acute phase, by inoculating NMRI mice with isolates, which were characterized by RAPD such as Zimodeme 1 (Z1= T. cruzi I) and obtained from Panstrongylus geniculatus, Rhodnius prolixus, Didelphis marsupialis, anal glands from these marsupials, Rattus rattus and humans from urban and rural areas of Venezuela. Animals with high parasite levels (1-10/31-40 pseudocysts/50 fields 400X) were sacrificed during the high infection level phase, with the presence of amastigotes or trypomastigotes which were produced in mice macrophages and adipocytes. The results show that T. cruzi populations can usually colonize fat tissues, regardless of the host or the geographic areas in which they were isolated. The study of this tissue is recommended in research on the characterization of this parasitosis. The results are discussed in relation to the findings of T. cruzi in special habitats, such as the fat rich marsupial anal glands, since their polymorphism and metacyclogenesis are dependent on adequate levels of lipid materials

Magnetic properties for the Mn2GeTe4 compound

Measurements of magnetic susceptibility χ, in the temperature range from 2 to 300 K, and of magnetization M vs. applied magnetic field B, up to 5 T, at various temperatures were made on polycrystalline samples of the Mn2GeTe4 compound. It was found that Mn2GeTe4 has a Néel temperature TN of about 135 K, shows mainly antiferromagnetic behavior with a very weak superimposed ferromagnetic component that is attributed to spin canting. Also, the magnetic results suggest that a possible spin-glass transition takes place at Tf≈45 K. The spin-glass order parameter q(T), determined from the susceptibility data, was found to be in agreement with the prediction of conventional spin-glass theory. The M vs. B results indicated that bound magnetic polarons (BMPs) occur in the compound, and that the effects from BMPs disappear at approximately 80 K. The M vs. B curves were well fitted by a Langevin type of equation, and the variation of the fitting parameters determined as a function of temperature. Using a simple spherical model, the radius of the BMP in the material was found to be about 27 Å; this value is similar to the effective Bohr radius for an acceptor in the II-IV-V2 and I-III-VI2 ternary semiconductor compounds. © 2008 Elsevier B.V. All rights reserved.Fil: Quintero, M.. Universidad de Los Andes Facultad de Ciencias; VenezuelaFil: Quintero, E.. Universidad de Los Andes Facultad de Ciencias; VenezuelaFil: Caldera, D.. Universidad de Los Andes Facultad de Ciencias; VenezuelaFil: Moreno, E.. Universidad de Los Andes Facultad de Ciencias; VenezuelaFil: Morocoima, M.. Universidad de Los Andes Facultad de Ciencias; VenezuelaFil: Grima, P.. Universidad de Los Andes Facultad de Ciencias; VenezuelaFil: Ferrer, D.. Universidad de Los Andes Facultad de Ciencias; VenezuelaFil: Marchan, N.. Universidad de Los Andes Facultad de Ciencias; VenezuelaFil: Bocaranda, P.. Universidad de Los Andes Facultad de Ciencias; VenezuelaFil: Delgado, G. E.. Universidad de Los Andes Facultad de Ciencias; VenezuelaFil: Henao, J. A.. Facultad de Ciencias; ColombiaFil: Macías, M. A.. Facultad de Ciencias; ColombiaFil: Pinto, J. L.. Facultad de Ciencias; ColombiaFil: Ponce Altamirano, Claudio Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentin