Genetic characterization of a core set of a tropical maize race Tuxpeño for further use in maize improvement.

The tropical maize race Tuxpeño is a well-known race of Mexican dent germplasm which has greatly contributed to the development of tropical and subtropical maize gene pools. In order to investigate how it could be exploited in future maize improvement, a panel of maize germplasm accessions was assembled and characterized using genome-wide Single Nucleotide Polymorphism (SNP) markers. This panel included 321 core accessions of Tuxpeño race from the International Maize and Wheat Improvement Center (CIMMYT) germplasm bank collection, 94 CIMMYT maize lines (CMLs) and 54 U.S. Germplasm Enhancement of Maize (GEM) lines. The panel also included other diverse sources of reference germplasm: 14 U.S. maize landrace accessions, 4 temperate inbred lines from the U.S. and China, and 11 CIMMYT populations (a total of 498 entries with 795 plants). Clustering analyses (CA) based on Modified Rogers Distance (MRD) clearly partitioned all 498 entries into their corresponding groups. No sub clusters were observed within the Tuxpeño core set. Various breeding strategies for using the Tuxpeño core set, based on grouping of the studied germplasm and genetic distance among them, were discussed. In order to facilitate sampling diversity within the Tuxpeño core, a minicore subset of 64 Tuxpeño accessions (20% of its usual size) representing the diversity of the core set was developed, using an approach combining phenotypic and molecular data. Untapped diversity represents further use of the Tuxpeño landrace for maize improvement through the core and/or minicore subset available to the maize community.

Social capital in settings with a high concentration of road traffic injuries. The case of Cuernavaca, Mexico.

There exists a differential ability within local communities to maintain effective social controls to prevent road traffic injuries (RTIs) in high risks areas. In 2002 we conducted a cross-sectional study in Cuernavaca, Mexico which incorporated 339 adults living in three areas which were characterized by high RTI concentrations. Multivariate analyses demonstrated that even when participants perceived RTIs as a local problem, they expressed no expectations that community members would exert social control through their involvement in local issues and law adherence. The study revealed four key conclusions regarding the association between the low levels of social capital and RTIs: (a) public roads are used solely for transportation, are not viewed as a communal space, and consequently reciprocity is not viewed as a relevant way of controlling behaviors in public places; (b) "strong immediate personal networks" bring about a lack of reciprocity between those sharing the public space which generates uncooperative behavior; (c) high levels of residential instability hinders the identification of common problems; (d) when there exists a low level of civic commitment and a scarcity of social resources directed towards the problem, the possibilities of social control over RTIs are low.

Epidemiological and nutritional transition in Mexico: rapid increase of non-communicable chronic diseases and obesity.

OBJECTIVE: The objective of this paper is to characterise the epidemiological and nutritional transition and their determinants in Mexico. DESIGN: Age-adjusted standardised mortality rates (SMRs) due to acute myocardial infarction (AMI), diabetes mellitus and hypertension were calculated for 1980-1998. Changes in the prevalences of overweight and obesity in women and children and of dietary intake from 1988 to 1999 were also used in the analysis. Quantities of food groups purchased by adult equivalent (AE) and food expenditures away from home between 1984 and 1989 were used to assess trends. All information was analysed at the national and regional levels, and by urban and rural areas. RESULTS: SMR for diabetes, AMI and hypertension increased dramatically parallel to obesity at the national and regional levels. Fat intake in women and the purchase of refined carbohydrates, including soda, also increased. DISCUSSION: The results suggest that obesity is playing a role in the increased SMRs of diabetes, AMI and hypertension in Mexico. Total energy dietary intake and food purchase data could not explain the rise in the prevalence of obesity. The increases in fat intake and the purchase of refined carbohydrates may be risk factors for increased mortality. Information on physical activity was not available. CONCLUSION: SMRs due to diabetes, hypertension and AMI have increased dramatically in parallel with the prevalence of obesity; therefore actions should be taken for the prevention of obesity. Reliable information about food consumption and physical activity is required to assess their specific roles in the aetiology of obesity.

Methodology in the epidemiological research of respiratory diseases and environmental pollution.

There are complex and diverse methodological problems involved in the clinical and epidemiological study of respiratory diseases and their etiological factors. The association of urban growth, industrialization and environmental deterioration with respiratory diseases makes it necessary to pay more attention to this research area with a multidisciplinary approach. Appropriate study designs and statistical techniques to analyze and improve our understanding of the pathological events and their causes must be implemented to reduce the growing morbidity and mortality through better preventive actions and health programs. The objective of the article is to review the most common methodological problems in this research area and to present the most available statistical tools used.

Methodology in the epidemiological research of respiratory diseases and environmental pollution

Existem problemas metodológicos diversos e complexos envolvidos no estudo clínico e epidemiológico de doenças respiratórias e seus fatores etiológicos. A associaçäo do crescimento urbano, da industrializaçäo e da deterioraçäo ambiental com as doenças respiratórias torna necessário focalizar a atençäo a esse campo de estudo com uma abordagem multidisciplinar. Devem ser implementados modelos de estudo e técnicas estatísticas adequadas para analisar e melhorar o entendimento sobre os eventos patológicos e suas causas e para reduzir a crescente morbimortalidade fazendo uso de medidas preventivas e melhores programas de saúde. O objetivo do artigo é revisar os problemas metodológicos mais comuns nessa área de pesquisa e apresentar os métodos estatísticos usados de maior acesso

México: comportamiento reproductivo y marginación social 1970-1990. Elementos para un diagnóstico geográfico en salud reproductiva / Mexico: reproductive behavior and social deprivation: 1970-1990. elements for a geographical diagnosis in reproductive health

La falta de conocimiento relativamente claro acerca de las características del comportamineto reproductivo regional, dificulta la evaluación de las metas propuestas por la Ley General de Población y hace improductivo cualquier esfuerzo por relacionar la población con el desarrollo regional. Este trabajo está ubicado en la perspectiva de la superación de esta situación. Se estimaron tasas específicas de fecundidad y tasas globales de fecundidad (TFG) a nivel estatal a través de técnicas indirectas. Se utilizó información censal y estadísticas vitales para las entidades federativas en el periodo 1970-1990. Para contextualizarlo, el comportamiento reproductivo se relacionó con los índices de marginación social elaborados por el Programa Nacional de Solidaridad y el Consejo Nacional de Población para esos mismos años. Se encontró una correlación alta y estadísticamente significativa (p< 0.01) entre los niveles de marginación y fecundidad en todo el periodo. Igualmente, se encontró una relación inversa estadísticamente signiicativa (p< 0.01) entre los niveles de marginación estatales y las velocidades de descenso en las TGF para las décadas en estudio. Se concluye que en las TGF hubo un descenso generalizado aunque no uniforme al interior del país. En este trabajo se plantea la necesidad de profundizar el análisis en el sentido de que las diferencias en los niveles de fecundidad y sus velocidades de descenso podrían estar sobredeterminadas por los distintos niveles de marginación, más que por la efectividad y generalización de los programas de planificación familiar. El mapeo de estos resultados se puede utilizar como un elemento de diagnóstico del comportamiento reproductivo de la población, a la vez que brinda la información necesaria para elaborar una respuesta social organizada en materia de salud reproductiva

The lack of a definite knowledge on regional reproductive behavior characteristics hinders the evaluation of the goals stated in the General Population Law (Ley General de Población) and counteracts any efforts towards equating population growth with regional development. The present work aims at overcoming this problem. Indirect specific fertility rates and global fertility rates (GFR) were obtained by state, using census and vital statistics data for the states of Mexico during the 1970-1990 period. Reproductive behavior was related to social deprivation indexes used by PRONASOL and CONAPO for those years. A high statistically significant correlation (p< 0.01) between state social deprivation levels and the downward trends of GFR for the same decades was found. Findings evidence a general downward trend of GFR during the period of study. However, this trend was not uniform across the country. Further studies are needed to determine whether these differences are due to the various social deprivation levels rather than to the effectiveness and extension of family planning programs. Mapping these results could be useful as diagnostic elements of the reproductive behavior of the population and also generates information necessary to support social organized responses in reproductive health.