Low 25-Hydroxyvitamin D [25(OH)D] Levels as a Predictor of Depressive Symptoms: Evidence from Community-Dwelling Older Adults Population in Mexico City.

OBJECTIVE: The purpose of this study was to assess the association between serum 25-hydroxyvitamin D [25(OH)D] levels and depressive symptoms in Mexican older adults 70 years and older. METHODS: A total of 326 adults aged 70 or older from Coyoacán Cohort Study were included in this study. The depressive symptoms were assessing by Center for Epidemiologic Studies Depression Scale (CES-D) and serum 25-hydroxyvitamin D [25(OH)D] levels were measured by commercially available enzyme-linked immunosorbent assay (ELISA). RESULTS: Overall, the prevalence of depressive symptoms was 36.5%. The mean age was 79 years, and 53.4% were women. The total serum 25-hydroxyvitamin D [25(OH)D] levels were lower in older adults with depressive symptoms when compared with older adults without depressive symptoms (p = .006). Logistic regression models showed a significant association between low serum 25(OH)D levels and depressive symptoms even after adjusting for potential confounders (OR = 2.453; 95% CI:1.218-4.939; p = .012). In addition, linear regression model to predict the effect of 25-hydroxyvitamin D [25(OH)D] levels on the CES-D score as a continuous variable, was statistically significant [F(1,324) = 8.54, p = .004], and the R-squared value was .026, indicating that this regression model explains 2.6% of the change in the CES-D score. CONCLUSION: These results suggest that older Mexican adults with lower serum 25-hydroxyvitamin D [25(OH)D] levels are at higher risk of presenting depressive symptoms.

A capillary fraction collector coupled to a fluorescence reader: a novel device to continuously quantify glutamate during microdialysis.

Microdialysis coupled to HPLC is the preferred method for quantification of glutamate (Glu) concentrations, both in normal and pathological conditions. However, HPLC is a time consuming technique that suffers from poor temporal resolution. Here we describe an alternative method to measure glutamate concentrations in small-volume dialysis samples by quantifying hydrogen peroxide released by glutamate oxidase using the Amplex Red method. This system permits continuous automatic sample collection and the detection of a fluorescent reaction product, resorufin, which provides a measure of the glutamate concentration. Quantification can be carried out in small microdialysis samples to allow a temporal resolution of 60 s. Both in vitro and in vivo tests showed that this method was reproducible and reliable, detecting Glu along a linear scale. To validate the proposed method, extracellular Glu concentrations in the rat brain were measured and correlated with electrophysiological activity prior, during and after seizure induction with 4-aminopyridine. This method may be adapted to monitor other biologically active compounds, including acetylcholine and glucose, as well as other compounds that generate hydrogen peroxide as a reaction product and may be used as an alternative to other neurochemical methods.