Usefulness of PCR-based assays to assess drug efficacy in Chagas disease chemotherapy: value and limitations

One major goal of research on Chagas disease is the development of effective chemotherapy to eliminate the infection from individuals who have not yet developed cardiac and/or digestive disease manifestations. Cure evaluation is the more complex aspect of its treatment, often leading to diverse and controversial results. The absence of reliable methods or a diagnostic gold standard to assess etiologic treatment efficacy still constitutes a major challenge. In an effort to develop more sensitive tools, polymerase chain reaction (PCR)-based assays were introduced to detect low amounts of Trypanosoma cruzi DNA in blood samples from chagasic patients, thus improving the diagnosis and follow-up evaluation after chemotherapy. In this article, I review the main problems concerning drug efficacy and criteria used for cure estimation in treated chagasic patients, and the work conducted by different groups on developing PCR methodologies to monitor treatment outcome of congenital infections as well as recent and late chronic T. cruzi infections

The Famatinian orogen along the protomargin of Western Gondwana: Evidence for a nearly continuous Ordovician magmatic arc between Venezuela and Argentina

The continental protomargin of Western Gondwana in South America records an important Early-Middle Ordovician magmatic activity associated with the development of the Famatinian orogen. Almost the entire margin has evidence of a magmatic arc preserved as orthogneisses in the high grade metamorphic domains up to volcanic rocks of the same age interfingered with sedimentary facies. These subduction related calcalkaline rocks have new UPb zircon dates that show striking similar ages bracketed between 490 and 460 Ma. The different domains along the continental margin are compared taking the western Sierras Pampeanas as the type locality, showing an alternation among high grade metamorphic – greenschist facies – sedimentary facies. There are three deeply-exhumed segments preserved as orthogneisses in high grade amphibolite facies, the Sierras Pampeanas, the Marañón and the Santander-Mérida domains. These domains are flanked by greenschist facies such as the Quetame in Colombia, the Vilcabamba in Perú, and the Puna Eruptive Belt in northern Argentina. Some segments are characterized by sedimentary facies as the Altiplano domain of Bolivia and the Olmos-Loja domain between Perú and Ecuador. The location and metamorphic grade are controlled by the amount of shortening and uplift, responsible for the different crustal levels exposed, as a consequence of the characteristics of the distinct terranes that collided against the continental margin. As a final remark, the time span of the Famatinian episode when globally compared has a widespread development in Laurentia, Baltica, and Australia, as a consequence of a period of high mobility of the plates during Early-Middle Ordovician times.Fil: Ramos, Victor Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentin