Vitamin D status and latent tuberculosis infection : a preliminary study in a group of healthy Mexican agricultural workers

Vitamin D metabolites are important in the regulation of bone and calcium homeostasis, but also have a more ubiquitous role in the regulation of cell differentiation and immune function. Severely low circulating 25-dihydroxyvitamin D [25(OH)D] concentrations have been associated with the onset of active tuberculosis (TB) in immigrant populations, although the association with latent TB infection (LTBI) has not received much attention. A previous study identified the prevalence of LTBI among a sample of Mexican migrant workers enrolled in Canada's Seasonal Agricultural Workers Program (SA WP) in the Niagara Region of Ontario. The aim of the present study was to determine the vitamin D status of the same sample, and identify if a relationship existed with LTBI. Studies of vitamin D deficiency and active TB are most commonly carried out among immigrant populations to non-endemic regions, in which reactivation of LTBI has occurred. Currently, there is limited knowledge of the association between vitamin D deficiency and LTBI. Entry into Canada ensured that these individuals did not have active TB, and L TBI status was established previously by an interferon-gamma release assay (IGRA) (QuantiFERON-TB Gold In-Tube®, Cellestis Ltd., Australia). Awareness of vitamin D status may enable individuals at risk of deficiency to improve their nutritional health, and those with LTBI to be aware of this risk factor for disease. Prevalence of vitamin D insufficiency among the Mexican migrant workers was determined from serum samples collected in the summer of 2007 as part of the cross sectional LTBI study. Samples were measured for concentrations of the main circulating vitamin D metabolite, 25(OH)D, with a widely used 1251 250HD RIA (DiaSorin Inc.®, Stillwater, MN), and were categorized as deficient «37.5 nmoI/L), insufficient (>37.5 nmollL, < 80 nmol/L) or sufficient (2::80 nmoI/L). Fisher's exact tests and t tests were used to determine if vitamin D status (sufficiency or insufficiency) or 25(OH)D concentrations significantly differed by sex or age categories. Predictors of vitamin D insufficiency and 25(OH)D concentrations were taken from questionnaires carried out during the previous study, and analyzed in the present study using multiple regression prediction models. Fisher's exact test and t test was used to determine if vitamin D status or 25(OH)D concentration differed by LTBI status. Strength of the relationship between interferongamma (IFN-y) concentration (released by peripheral T cells in response to TB antigens) and 25(OH)D concentration was analyzed using a Spearman correlation. Out of 87 participants included in the study (78% male; mean age 38 years), 14 were identified as LTBI positive but none had any signs or symptoms of TB reactivation. Only 30% of the participants were vitamin D sufficient, whereas 68% were insufficient and 2% were deficient. Significant independent predictors of lower 25(OH)D concentrations were sex, number of years enrolled in the SA WP and length of stay in Canada. No significant differences were found between 25(OH)D concentrations and LTBI status. There was a significant moderate correlation between IFN-y and 25(OH)D concentrations ofLTBI-positive individuals. The majority of participants presented with Vitamin D insufficiency but none were severely deficient, indicating that 25(OH)D concentrations do not decrease dramatically in populations who temporarily reside in Canada but go back to their countries of origin during the Canadian winter. This study did not find a statistical relationship between low levels of vitamin D and LTBI which suggests that in the presence of overall good health, lower than ideal levels of 2S(OH)D, may still be exerting a protective immunological effect against LTBI reactivation. The challenge remains to determine a critical 2S(OH)D concentration at which reactivation is more likely to occur.

The mexican war : a history of its origen, and a detailed account of the victories wich terminated in the surrender of the capital ; with the official despatches of the generals. To which is added, the Treaty of Peace, and valuable tables of the strength and losses of the United States Army.

UANL

The mexican war and its warriors : comprising a complete history of all the operations of the American armies in Mexic...

UANL

Recollections of a Virginian in the mexican, indian, and civil wars

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Two wars, an autobiography of Gen. Samuel G. French... mexican war ; war between the states, a diary ; reconstruction period, his experiences ; incidents, reminiscences, etc.

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Report of the Secretary of War, communicating; in compliance witha resolution of the Senate, a map showing the operations of the army of the United States in Texas and the adjacent Mexican Stateson the Rio Grande, accompanied by astronomical observations, and descriptive and military memoirs of the country.

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Mexican vistas : seen from Highways and Byways of travel

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Color studies and a mexican campaign

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Album del ferrocarril mexicano : colección de vistas pintadas del natural. Album of the mexican raulway : a collection of views taken from nature

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Memoirs of the Mexican Revolution : including a narrative of the expedition of General Xavier Mina. To which are annexed some observations on the practicability of opening a commerce between the Pacific and Atlantic oceans, through the Mexican isthmus, in the province of Oaxaca, and at the Lake of Nicaragua; and the vast importance of such commerce to the civilized world.

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Papers relative to mexican affairs: communicated to the Senate june 16, 1864

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Valuing Sovereign Default Risk - A Pricing Formula and its Empirical Results for the Mexican External Debt.

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Fenn's english dialogues, for mexican students a supplement the author's fourth english reader

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Protective Liberalization : the state and the Mexican petrochemical industry 1958-2000

This thesis follows and analyses the involvement of both social actors and the state in the industrial transformation of Mexico. While these actors have been key associates in the development of the Mexican economy for decades, with the 1982 debt crisis, and especially after the promotion of a structural reform in 1986, the patterns of their involvement changed. However, this change was more limited than expected, and the state did not abandon its participation in some key industrial sectors. This thesis will demonstrate that the role of the state remained important during the process of change towards an Export-Oriented developmental paradigm, although the state continued to participate in fashioning social relations, it did so in new ways that can be termed “protective liberalization.”