These data suggest that long-term coffee consumption is associated with a statistically significantly lower risk for type 2 diabetes.

Background: In animal studies of the effects of hormonally active agents, measurement of anogenital distance (AGD) is now routine, and serves as a bioassay of fetal androgen action. Although measurement of AGD in humans has been discussed in the literature, to our knowledge it has been measured formally in only two descriptive studies of females. Because AGD has been an easy-to-measure, sensitive outcome in animals studies, we developed and implemented an anthropometric protocol for measurement of AGD in human males as well as females.

Background: Variations in the incidence of cancer can be influenced by diet and specific lifestyles. In the last years, diet has been evaluated as an important factor in the development of ovarian cancer, even though the results have not been consistent. Dietary factors related to the risk of ovarian cancer in Mexican women were evaluated. Methods: A case-control study in Mexico City was done during 1995–1997 in a social security hospital, evaluating 84 new cases of ovarian cancer and 629 controls. A validated questionnaire with 116 items about the frequency and type of food intake was used. The analysis of nutrients was done with the residual method adjusted for total energy intake and other predictor variables through logistic regression methods. Also, partition models estimated the total caloric intake for other sources. Results: The nutrients negatively associated with ovarian cancer in the highest versus the lowest tertile were retinol (OR 0.52; p for trend = 0.03) and vitamin D (OR 0.43; 95% CI 0.23–0.80; p = 0.01; residual model). Additionally, carbohydrates were positively associated (partition model: OR 1.08; 95% CI 1.00–1.15), and tortilla intake did not show an association with ovarian cancer (OR 0.96; 95% CI 0.78–1.17). Conclusions: The diet of the Mexican population is rich in carbohydrates; in Mexico corn intake is the main energy source. On the other hand, vitamins such as retinol and vitamin D were shown to be associated with this neoplasm in a protective way; nevertheless, further studies are necessary to allow us to corroborate our results. This is the first attempt in our country that relates the Mexican diet to ovarian cancer.

Daily diet factors that could potentially be related to endometrial cancer (EC) in Mexico are still unknown. This study aims to evaluate the association between EC and Mexican dietary factors. A case-control study in Mexico City was conducted during 1995-1997 in a social security hospital, using 85 incident cases of EC and 629 controls. A validated questionnaire with 116 items about the frequency and type of food intake was used. The analysis of nutrients was performed using the residual method, adjusting by predictor variables through logistic regression methods. In addition, partitional models estimated total caloric intake for other sources. We found no association between EC risk and consumption of animal or vegetable proteins, saturated, monounsaturated, or polyunsaturated fat, although high intake of nutrients such as lactose (odds ratio [OR], 0.46; 95% confidence interval [CI], 0.21-1.01, P for trend = 0.004), vitamin D (OR, 0.38; 95% CI, 0.18-0.82, P= 0.003), and calcium (OR, 0.39; 95% CI, 0.17-0.89, P= 0.02) were inversely associated with EC. Our results suggest that dietary vitamin D and calcium play an important role in the development of EC, although the mechanisms postulated should be explained with additional studies with large populations.

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The aim of this study was to analyse the influence of inspiratory muscle training (IMT) on ventilatory efficiency, in normoxia and hypoxia, and to investigate the relationship between ventilatory efficiency and cycling performance. Sixteen sport students (23.05 ± 4.7 years; 175.11 ± 7.1 cm; 67.0 ± 19.4 kg; 46.4 ± 8.7 ml·kg−1·min−1) were randomly assigned to an inspiratory muscle training group (IMTG) and a control group (CG). The IMTG performed two training sessions/day [30 inspiratory breaths, 50% peak inspiratory pressure (Pimax), 5 days/week, 6-weeks]. Before and after the training period subjects carried out an incremental exercise test to exhaustion with gas analysis, lung function testing, and a cycling time trial test in hypoxia and normoxia. Simulated hypoxia (FiO2 = 16.45%), significantly altered the ventilatory efficiency response in all subjects (p < 0.05). Pimax increased significantly in the IMTG whereas no changes occurred in the CG (time × group, p < 0.05). Within group analyses showed that the IMTG improved ventilatory efficiency (VE/VCO2 slope; EqCO2VT2) in hypoxia (p < 0.05) and cycling time trial performance [WTTmax (W); WTTmean (W); PTF(W)] (p < 0.05) in hypoxia and normoxia. Significant correlations were not found in hypoxia nor normoxia found between ventilatory efficiency parameters (VE/VCO2 slope; LEqCO2; EqCO2VT2) and time trial performance. On the contrary the oxygen uptake efficiency slope (OUES) was highly correlated with cycling time trial performance (r = 0.89; r = 0.82; p < 0.001) under both conditions. Even though no interaction effect was found, the within group analysis may suggest that IMT reduces the negative effects of hypoxia on ventilatory efficiency. In addition, the data suggest that OUES plays an important role in submaximal cycling performance.

U n objetivo en todo estudio epidemiológico, en el que se desea conocer la frecuencia con la que ocurre un evento o estimar la asociación entre un factor de riesgo y una enfermedad, debe ser el de medir y calcular con la mayor precisión y exactitud posibles dichas determinaciones. En otras palabras, la validez del conocimiento derivado de cualquier estudio epidemiológico dependerá, en gran medida, de la ausencia de error y de la capacidad de estimar o predecir el parámetro verdadero en la población blanco. En el contexto de la epidemiología, la validez se refiere a la ausencia de sesgo o error. A lo largo del presente trabajo se hace referencia a dos tipos de validez: a) la validez interna, que se refiere principalmente a los errores cometidos durante el proceso de selección de la población de estudio, durante las mediciones que se realizan en dicha población o a errores ocasionados por la falta de comparabilidad de los grupos estudiados, y b) la validez externa, que se refiere a la capacidad del estudio de generalizar los resultados observados en la población en estudio hacia la población blanco. Es importante notar que la validez externa depende de que exista la interna, es decir, es necesario cumplir con los requisitos necesarios de validez interna para poder extrapolar lo resultados, por esta razón en los diferentes estudios epidemiológicos se privilegian acciones que maximizan la validez interna, aun comprometiendo, en cierta medida, la validez externa. Sesgos en estudios epidemiológicosMauricio Hernández-Avila, Ph.D., (1) Francisco Garrido, M.C., M. en C., (2) Eduardo Salazar-Martínez, Dr. en C. (1) Todo estudio epidemiológico está sujeto a un cierto margen de error, por lo que será muy importante conocer cuáles son sus fuentes principales y los diferentes procedimientos que pueden ser utilizados para minimizar su impacto en los resultados. Los errores se pueden clasificar en dos grandes tipos: los errores no aleatorios o sistemáticos y los errores aleatorios (no sistemáticos); ambos tipos de error, de no controlarse adecuadamente, pueden comprometer la validez del estudio. El error aleatorio (no sistemá-tico) ocurre cuando las mediciones repetidas, ya sean en un mismo sujeto o en diferentes miembros de la población en estudio, varían de manera no predecible, mientras que el error sistemático (no aleatorio) ocurre cuando estas medidas varían de manera predecible y, por lo tanto, se tiende a sobre o subestimar el valor verdadero en medidas repetidas. La analogía que se utiliza para describir ambos conceptos es la práctica de "tiro al blanco" donde el punto medio del objetivo es el valor verdadero en la población blanco y los "disparos" son las diferentes mediciones que se realizan en la población en estudio para estimar dicho valor verdadero. Un buen tirador cuya arma no está bien calibrada apuntará al blanco equivocado, podrá ser muy preciso (todos los disparos dan en el mismo lugar), pero ninguno de ellos da en el blanco correcto. Esto corresponde al error sistemático. Por otra parte, un tirador con mano ...

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