The association between the essential metal mixture and fasting plasma glucose in Chinese community-dwelling elderly people.

BACKGROUND: Epidemiological studies about the effect of essential metal mixture on fasting plasma glucose (FPG) levels among elderly people are sparse. The object of this study was to examine the associations of single essential metals and essential metal mixture with FPG levels in Chinese community-dwelling elderly people. METHODS: The study recruited 2348 community-dwelling elderly people in total. Inductively coupled plasma-mass spectrometry was adopted to detect the levels of vanadium (V), selenium (Se), magnesium (Mg), cobalt (Co), calcium (Ca), and molybdenum (Mo) in urine. The relationships between single essential metals and essential metal mixture and FPG levels were evaluated by linear regression and Bayesian kernel machine regression (BKMR) models, respectively. RESULTS: In multiple-metal linear regression models, urine V and Mg were negatively related to the FPG levels (ß = - 0.016, 95 % CI: - 0.030 to - 0.003 for V; ß = - 0.021, 95 % CI: - 0.033 to - 0.009 for Mg), and urine Se was positively related to the FPG levels (ß = 0.024, 95 % CI: 0.014-0.034). In BKMR model, the significant relationships of Se and Mg with the FPG levels were also found. The essential metal mixture was negatively associated with FPG levels in a dose-response pattern, and Mg had the maximum posterior inclusion probability (PIP) value (PIP = 1.0000), followed by Se (PIP = 0.9968). Besides, Co showed a significant association with decreased FPG levels in older adults without hyperlipemia and in women. CONCLUSIONS: Both Mg and Se were associated with FPG levels, individually and as a mixture. The essential metal mixture displayed a linear dose-response relationship with reduced FPG levels, with Mg having the largest contribution to FPG levels, followed by Se. Further prospective investigations are necessary to validate these exploratory findings.

Selenium attenuates the association of co-exposure to arsenic, cadmium, and lead with cognitive function among Chinese community-dwelling older adults.

The effects of interactions between the toxic and essential metal mixtures on cognitive function are poorly understood. This study aims to identify the joint association of arsenic (As), cadmium (Cd), and lead (Pb) with cognitive function in older adults and the moderating role of selenium (Se), zinc (Zn), and copper (Cu) in this association. This study included 1000 community-dwelling older adults. Cognitive function was assessed by the Mini-Mental State Examination (MMSE). Blood concentrations of As, Cd, Pb, Se, Zn, and Cu were measured using inductively coupled plasma mass spectrometry. Linear regression and Bayesian kernel machine regression (BKMR) models were applied to assess the individual and joint associations of As, Cd, and Pb with cognitive function and to examine whether Se, Zn, and Cu (individually and as a mixture) modified these associations. In the adjusted single-metal models, both Cd (ß = - 0.37, 95% CI: - 0.73 to - 0.01) and Pb (ß = - 0.44, 95% CI: - 0.86 to - 0.02) were associated with MMSE scores, while Se (ß = 0.71, 95% CI: 0.30 to 1.13) exhibited a positive relationship with MMSE scores. Univariate exposure-response functions from BKMR models showed similar results. Moreover, the toxic metal mixture (As, Cd, and Pb) exhibited a significant negative association with MMSE scores in a dose-response pattern, with Pb being the greatest contributor within the mixture. The negative association of Pb alone or the toxic metal mixture with MMSE scores became weaker at higher concentrations of Se within its normal range, especially when Se levels were greater than the median (89.18 µg/L). Our findings support that Se can attenuate the negative associations of exposure to single Pb or the As, Cd, and Pb mixtures with cognitive function. Future prospective studies are needed to replicate our findings.

The effect of Zn(2+) on Pelodiscus sinensis creatine kinase: unfolding and aggregation studies.

We studied the effects of Zn(2+) on creatine kinase from the Chinese soft-shelled turtle, Pelodiscus sinensis (PSCK). Zn(2+) inactivated the activity of PSCK (IC(50) = .079 ± .004 mM) following first-order kinetics consistent with multiple phases. The spectrofluorimetry results showed that Zn(2+) induced significant tertiary structural changes of PSCK with exposure to hydrophobic surfaces and that Zn(2+) directly induced PSCK aggregation. The addition of osmolytes such as glycine, proline, and liquaemin successfully blocked PSCK aggregation, recovering the conformation and activity of PSCK. We measured the ORF gene sequence of PSCK by rapid amplification of cDNA end and simulated the 3D structure of PSCK. The results of molecular dynamics simulations showed that eight Zn(2+) bind to PSCK and one Zn(2+) is predicted to bind in a plausible active site of creatine and ATP. The interaction of Zn(2+) with the active site could mostly block the activity of PSCK. Our study provides important insight into the action of Zn(2+) on PSCK as well as more insights into the PSCK folding and ligand-binding mechanisms, which could provide important insight into the metabolic enzymes of P. sinensis.