Relationship between short-term self-reported dietary magnesium intake and whole blood ionized magnesium (iMg2+) or serum magnesium (s-Mg) concentrations

AbstractObjective Since we and others have shown that supplemental magnesium raises whole blood ionized magnesium (iMg2+) we investigated the relationships between self-reported dietary magnesium intake and concentrations of whole blood iMg2+ and serum magnesium (s-Mg).Methods We obtained whole blood iMg2+ concentrations, as well as s-Mg concentrations, from a pilot, three-arm, randomized, controlled, crossover bioavailability study of magnesium supplements (n = 23; 105 measures). Dietary magnesium intake was assessed using three-day food records and the Nutrition Data System for Research (NDSR, University of Minnesota, MN, USA). Whole blood iMg2+ was measured with an electrode analyser (NOVA Biochemical, Waltham, MA, USA), whereas s-Mg was measured using atomic absorption spectroscopy. A linear mixed-effects model was employed with dietary magnesium as the outcome variable and iMg2+, s-Mg, study treatment and study visit as fixed effects. We adjusted age, gender, race and body mass index covariates.Results Values for dietary magnesium, iMg2+ and s-Mg were 303.8 ± 118.9 mg/day, 1.3 ± 0.1 mg/dL and 2.2 ± 4.1 mg/dL, respectively. No association was found between dietary magnesium intake and iMg2+ −125 ± 176.95 (p = .49) or s-Mg −9.33 ± 5.04 (p = .08).Conclusions Whole blood iMg2+ and s-Mg concentrations do not reflect short-term self-reported dietary intake in adults. Further research is needed to determine whether blood biomarkers of magnesium may reflect dietary magnesium intake.Key messagesDietary intake of magnesium, a shortfall nutrient, may be objectively measured using blood biomarkers of magnesium.Serum magnesium and whole blood iMg2+ were not associated with short-term dietary intake of magnesium

Use of Moraxella catarrhalis Lipooligosaccharide Mutants To Identify Specific Oligosaccharide Epitopes Recognized by Human Serum Antibodies▿

Moraxella catarrhalis is a causative agent of otitis media in children and lower respiratory tract infections in adults suffering from chronic obstructive pulmonary disease (COPD). This strict human pathogen continues to be a significant cause of disease in this broad spectrum of patients because there is no available vaccine. Although numerous putative vaccine antigens have been described, little is known about the human immune response to M. catarrhalis infection in vivo. Human serum antibodies are directed at a number of surface proteins, and lipooligosaccharides (LOS) and detoxified LOS may be an effective immunogen in mice. In this study, we used a specific LOS-based enzyme-linked immunosorbent assay (ELISA), containing the three major M. catarrhalis serotypes together with a complete series of truncated LOS mutants, to detect the development of new antibodies to specific regions of the oligosaccharide molecule. We compared serum samples from COPD patients who had recently cleared an M. catarrhalis infection to serum samples collected prior to their infection. Variability in the antibody response to LOS was observed, as some patients developed serotype-specific antibodies, others developed antibodies to the LOS of each serotype, others developed broadly cross-reactive antibodies, and some did not develop new antibodies. These newly developed human antibodies are directed at both side chains and core structures in the LOS molecule. This LOS-based ELISA can be used to dissect the human antibody response to both internal and external carbohydrate epitopes, thus providing a better understanding of the humoral immune response to M. catarrhalis LOS epitopes developed during natural infection