Abstract: Languishing labor market conditions throughout Latin America, along with pull factors in countries such as the United States, point to continued and increased skilled migration from Latin America. The outflow of well-educated Salvadorans, Guatemalans, Peruvians, Venezuelans, Brazilians, and Mexicans in search of better incomes and career opportunities is well noted. Yet, important qualitative differences exist in terms of who does -and, important in this context who does not- emigrate and why? Drawing on interview data with Mexican professionals in Mexico City, in this article I suggest that social network theory is insufficient for understanding skilled migration from Mexico. Focusing on those who stay behind, I offer instead a sociocultural framework, one that emphasizes individuals’ own discursive renderings and that acknowledges that individuals’ decisions not to migrate are rooted in class-based dispositions, cultural beliefs, and social practices.

Resumen: El debilitamiento de las condiciones del mercado de trabajo en Latinoamérica, además de los factores de atracción en países como Estados Unidos, indican que la migración calificada continuará y se incrementará. El flujo de salida de salvadoreños, guatemaltecos, peruanos, venezolanos, brasileños y mexicanos bien preparados en busca de mejores salarios y oportunidades de desarrollo en sus carreras es evidente. Aun así, existen importantes diferencias cualitativas en términos de quién -y algo muy importante en este contexto, quién no- emigra y por qué. A partir de un trabajo con datos de entrevistas con profesionistas mexicanos en la Ciudad de México, en este artículo se sugiere que la teoría social de redes es insuficiente para entender la migración calificada desde México. El enfoque se centra en quienes se quedan, y se ofrece, en lugar de un marco sociocultural, uno que enfatiza las perspectivas propias del discurso de los individuos y que reconoce que las decisiones individuales de no migrar se encuentran enraizadas en situaciones basadas en la clase, las creencias culturales y las prácticas sociales.

Nitroarylidenemalononitriles and their cyanoacetamide derivatives with remarkable anti-epimastigote properties, were synthesized attempting to obtain new 3,5-diamino-4-(5'-nitroarylidene)-4H-thiadiazine 1,1-dioxide derivatives, which in previous reports had shown anti-Trypanosoma cruzi activity. Tests to evaluate the cytotoxicity of compounds were performed on J774 macrophages. 5-nitro-2-thienyl-malononitrile (5NO2TM), was the only product which maintained a high anti-epimastigote activity at concentrations in which it was no longer cytotoxic, thus it was assayed against intracellular amastigotes. Its anti-amastigote activity was similar to that of nifurtimox. Afterwards in vivo toxicity and anti-chagasic activity were determined. A reduction in parasitemia was observed.

Cytotoxicity assays of 24 new 3,5-disubstituted-tetrahydro-2H-1,3,5-thiadiazin-2-thione derivatives were performed. The 17 compounds with higher anti-epimastigote activity and lower cytotoxicity were, thereafter, screened against amastigote of Trypanosoma cruzi. Out of these 17 derivatives S-2d was selected to be assayed in vivo, because of its remarkable trypanocidal properties. To determine toxicity against J774 macrophages, a method based on quantification of cell damage, after 24 h, was used. Cell respiration, an indicator of cell viability, was assessed by the reduction of MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] to formazan. Anti-amastigote activity was estimated after 48 h by microscopic counts of May Grünwald-Giemsa-stained monolayers. Nifurtimox and benznidazole were used as reference drugs. For the in vivo experiences, mice were infected with 10(4) blood trypomastigotes and then treated during 15 days with S-2d or nifurtimox by oral route. All of the compounds were highly toxic at 100 µg/ml for macrophages and a few of them maintained this cytotoxicity even at 10 µg/ml. Of the derivatives assayed against amastigotes 3k and S-2d showed an interesting activity, that was held even at 1µg/ml. It is demonstrated that the high anti-epimastigote activity previously reported is mainly due to the non-specific toxicity of these compounds. In vivo assays assessed a reduction of parasitemia after administration of S-2d to infected mice.