Intervalos de referencia para 25-hidroxivitamina D en población autóctona y aparentemente sana de Yucatán / Reference values for 25-hydroxy-vitamin D in a native and apparently healthy population from Yucatan, Mexico

Introducción: La 25-hidroxivitamina D [25(OH)D] se considera un marcador del estado general de salud y su deficiencia es un problema a nivel mundial. En la actualidad no existe un consenso para definir sus niveles óptimos, siendo necesario establecerlos para cada población de acuerdo con sus características étnicas y factores ambientales a los que está expuesta. Objetivo: Determinar los intervalos de referencia para 25(OH)D en población autóctona y aparentemente sana de Yucatán. Métodos: Se estudiaron 71 voluntarios aparentemente sanos, de uno u otro sexo, de uno a 65 años, originarios y residentes en Yucatán. Se determinaron los niveles séricos de 25(OH)D, así como los de calcio, fósforo y paratohormona por su relación con el metabolismo de la vitamina D. Los intervalos de referencia se calcularon con los métodos paramétrico y consistente. Se registró el fototipo de piel y se aplicó el test de Garabédian para determinar el consumo diario de calcio y vitamina D. Resultados: El valor medio de 25(OH)D fue de 23,49±5,60ng/mL. Los límites de referencia para 25(OH)D total y por sexos fueron más estrechos y significativamente diferentes a los propuestos por el fabricante. Se encontró correlación directa entre los niveles de 25(OH)D y el calcio sérico (r=0,36; p=0,003) e inversa con la paratohormona intacta (r=−0,44; p<0,001). Una dieta rica en calcio y vitamina D no es suficiente para mantener los requerimientos normales de 25(OH)D en esta población. Conclusiones: Los intervalos de referencia propuestos están adecuados a las peculiaridades de la población de Yucatán, y pudieran mejorar la exactitud de la medición del estado de salud con base en los niveles séricos de vitamina D

Introduction: 25-hydroxyvitamin D [25(OH)D] is considered a marker of general health and its deficiency is a problem worldwide. There is still no consensus to define their optimal levels, with it being necessary to establish them for each population according to their ethnic characteristics and environmental factors to which they are exposed. Objective: To determine the reference intervals for 25(OH)D in the native and apparently healthy population of Yucatan. Methods:The study included 71 apparently healthy volunteers, female and male, between one and 65 years old, and originally from Yucatan. Serum levels of 25(OH)D were measured along with the determination of calcium, phosphorus, and parathormone levels due to their relationship with vitamin D metabolism. Reference intervals were calculated using parametric and robust methods. The skin phototype was recorded and the Garabedian test was applied to determine the daily intake of calcium and vitamin D. Results: The mean value of 25(OH)D was 23.49±5.60ng/mL. The reference limits for total and gender-related 25(OH)D, and by gender were narrower and significantly different from those proposed by the manufacturer. A direct correlation was found between 25(OH)D levels and serum calcium (r=0.36; P=.003) and an inverse one with intact parathormone (r=−0.44; P<.001). A diet rich in calcium and vitamin D is not sufficient to maintain the normal requirements of 25(OH)D in this population. Conclusions: The proposed reference intervals are adequate to the peculiarities of the population of Yucatan and could improve the accuracy of health status measurement based on serum levels of vitamin D

Effect of a combination DNA vaccine for the prevention and therapy of Trypanosoma cruzi infection in mice: role of CD4+ and CD8+ T cells.

Chagas disease is a major public health problem, with about 10 million infected people, and DNA vaccines are a promising alternative for the control of Trypanosoma cruzi, the causing agent of the disease. We tested here a new DNA vaccine encoding a combination of two leading parasite antigens, TSA-1 and Tc24, for the prevention and therapy of T. cruzi infection. Immunized Balb/c mice challenged by T. cruzi presented a significantly lower parasitemia and inflammatory cell density in the heart compared to control mice. Similarly, the therapeutic administration of the DNA vaccine was able to significantly reduce the parasitemia and inflammatory reaction in acutely infected Balb/c and C57BL/6 mice, and reduced cardiac tissue inflammation in chronically infected ICR mice. Therapeutic vaccination induced a marked increase in parasite-specific IFNγ producing CD4(+) and CD8(+) T cells in the spleen as well as an increase in CD4(+) and CD8(+) T cells in the infected cardiac tissue. In addition, some effect of the DNA vaccine could still be observed in CD4-knockout C57BL/6 mice, which presented a lower parasitemia and inflammatory cell density, but not in CD8-deficient mice, in which the vaccine had no effect. These results indicate that the activation of CD8(+) T cells plays a major role in the control of the infection by the therapeutic DNA vaccine, and to a somewhat lesser extent CD4(+) T cells. This observation opens interesting perspectives for the potentiation of this DNA vaccine candidate by including additional CD8(+) T cell antigens/epitopes in future vaccine formulations.