ABSTRACT The present work analyzed the concentration of As, Cd, Pb, and Hg in sediment and the Hg concentration in fish muscle from two coastal lagoons in the states of Jalisco (Barra de Navidad Lagoon) and Colima (Cuyutlán Lagoon), Mexico. Both lagoons showed relatively low levels of metal contamination and potential health risk compared to other Mexican areas. A non-carcinogenic hazard quotient (HQ) was determined. As (10.7 ± 1.3 - 25.4 ± 3.1 µg g-1) and Pb (42.7 ± 4.2 - 123.9 ± 14.7 µg g-1) concentrations exceeded the permissible levels, otherwise for Hg and Cd were below the limits. The highest total mercury concentration was found in Haemulopsis sp. and Lutjanus sp. with 0.23 and 0.1 µg g-1 (wet weight) respectively, out of 14 species of fish analyzed that are frequently consumed locally. HQ based on the national daily per capita consumption of fish in Mexico and the consumption of fish associated with fishing communities in Mexico showed an HQs >2, which manifests the vulnerability of these communities to persistent toxic and bioaccumulative contaminants.

ABSTRACT Mexico is responsible for the protection and management of a large number and variety of aquatic bodies of national and international importance. Environmental pollution by so-called persistent and bioaccumulative toxic substances (PBTS) poses significant risks for all of the world's aquatic ecosystems, especially in countries with emerging economies, where environmental regulations are often poorly implemented. In Mexico, the development of industrial projects and the deficient application of environmental regulations, together with the rapid increase in population and the inefficient disposal of urban waste, have generated a severe problem of water pollution in the country. National environmental protection programs have not included the monitoring of PBTS, even though researchers have been monitoring the main aquatic ecosystems of the country for nearly three decades, generating valuable information that could help improve the protection and exploitation of these ecosystems. The present work reviewed a large portion of the available literature (∼150 articles) on aquatic biomonitoring of the main PBTS (Hg, Cd, Pb, POCs, and PCBs) in Mexico. This work aims to collect, synthesize, and facilitate the management and interpretation of the reported data to improve the country's aquatic ecosystems' protection and management.

This paper provides a short introduction to optimization problems with semidefinite constraints. Basic duality and optimality conditions are presented. For linear semidefinite programming some advances by dealing with degeneracy and the semidefinite facial reduction are discussed. Two relatively recent areas of application are presented. Finally a short overview of relevant literature on algorithmic approaches for efficiently solving linear and nonlinear semidefinite programming is provided.

La introducción de especies exóticas a ambientes nuevos, producto de actividades humanas, produce un impacto devastador e irreversible a los ecosistemas naturales. Como la acuicultura es una de las fuentes del problema, esta publicación revisa el papel de algunos gobiernos y organizaciones internacionales en el desarrollo de esta actividad. Concluimos que estas organizaciones deben reconsiderar el uso de paquetes tecnológicos que promueven la introducción de especies exóticas y en su lugar deben ayudar al desarrollo de tecnologías que promuevan el cultivo de especies nativas con potencial para la acuicultura. Esto requiere de investigación que permita conocer las condiciones optimas para el cultivo, lo cual permitirá además, mejorar las capacidades locales de investigación. Algunas agencias internacionales financiadoras pueden ejercer una gran influencia en promover estas nuevas prácticas.

The introduction of alien species in new environments, as a consequence of human activities, contributes to an irreversible and devastating impact to natural ecosystems. As aquaculture is one source of this problem, this paper reviews the role of some governments and international organizations in the development of this activity. We conclude that these organizations should reconsider the use of technical packages that encourage introduction of exotic species. Instead, they should help the development of technologies that propose to cultivate native species with potential for aquaculture. This will require research to determine optimal conditions for culture, and it will improve local research capacities. International technical funding agencies can exert a great influence in encouraging new practices.

A introdução de espécies exóticas a ambientes novos, produto de atividades humanas, produz um impacto devastador e irreversível aos ecossistemas naturais. Como a aqüicultura é uma das fontes do problema, esta publicação revisa o papel de alguns governos e organizações internacionais no desenvolvimento desta atividade. Concluímos que estas organizações devem reconsiderar o uso de pacotes tecnológicos que promovem a introdução de espécies exóticas e em seu lugar devem ajudar ao desenvolvimento de tecnologias que promovam o cultivo de espécies nativas com potencial para a aqüicultura. Isto requer de investigação que permita conhecer as condições ótimas para o cultivo, o qual permitirá alem disso, melhorar as capacidades locais de investigação. Algumas agências internacionais financiadoras podem exercer uma grande influência em promover estas novas práticas.

14 patients, 9 males and 5 females, with ischemic heart disease demonstrated by coronariography or myocardial perfusion study and positive ergometric test were included in this study. All of them underwent 3 consecutive ergometric tests (Erg. 1, Erg. II and Erg. III) with an interval of 30 min between Erg. I and Erg. II and of 24 h between Erg II and Erg III. Significant differences were found between the means of Erg. I and II (p <FONT FACE=Symbol>£</FONT> 0.01) and between Erg. I and III (p <FONT FACE=Symbol>£</FONT> 0.5) in the following variables: duration of ischemia (434 s ± 228, 300 s ± 177, 314 s ± 226); depression of the ST segment (-2.9 mm ± 1.3, -2.1 mm ± 1.3, -2.2 mm ± 1.1); variation of the slope of the ST/FC relation (-507 mm/s ± 188, -360 mm/s ± 225, -402 mm/s ± 180); and between Erg. 1 and Erg. III (p <FONT FACE=Symbol>£</FONT> 0.5) in the duration of angina (243 s ± 66, 172 s ± 109, 122 s ± 90). The double products in the variables measured increased in Erg. II and III compared with Erg. 1, but with no statistical significance p >.05. It was concluded that ischemia induced by exercise showed less evidence of ischemia at 30 min. A trend towards an ischemic reduction, although less intense, was also observed. The ischemic preconditioning may be the mechanism generating both cardioprotections.

El precondicionamiento isquémico posee un efecto cardioprotector que depende de mecanismos metabólicos. Nos propusimos demostrar a través de la isquemia inducida por el ejercicio, la presencia del precondicionamiento isquémico clásico y la segunda ventana. Se incluyeron 14 pacientes, 9 masculinos y 5 femeninos, con una cardiopatía isquémica demostrada por coronariografia o estudio de perfusión miocárdica y prueba ergométrica positiva. A todos se les realizó 3 pruebas ergométricas consecutivas (Erg. I, Erg. II y Erg. III), con un intervalo entre Erg I y Erg II de 30 min y entre Erg II y Erg III de 24 h. Se encontraron diferencias significativas entre las medias de Erg. I y II (p <FONT FACE=Symbol>£</FONT>,001) y entre Erg I y III ( p <FONT FACE=Symbol>£</FONT> ,05) en las variables: duración de la isquemia (434 s ± 228, 300 s ± 177, 314 s ± 226); depresión del segmento ST (-2,9 mm ± 1,3, -2,1 mm ± 1,3, -2,2 mm ± 1,1); variación de la pendiente de la relación ST/FC (-507 mm/s ± 188, -360 mm/s ± 225, - 402 mm/s ± 180); y entre Erg. I y Erg. III (p <FONT FACE=Symbol>£</FONT>,05) en la duración de angina (243 s ±66, 172 s ± 109, 122 s ± 90). Los doble productos en las variables medidas tuvieron incremento en Erg. II y III en relación con Erg. I, pero sin significación estadística p> , 05. Concluimos que la isquemia inducida por el ejercicio generó menor evidencia de isquemia a los 30 min. A las 24 h también se encontró una tendencia de reducción isquémica, aunque de menor intensidad. El precondicionamiento isquémico pudiera ser el mecanismo generador de ambas cardioprotecciones.