Size Fractionation of Metal Species from Serum Samples for Studying Element Biodistribution in Alzheimer’s Disease

Abstract

This work considers the development of a novel analytical procedure for rapid and simple size fractionation of metal species from human serum samples, with a great potential for studying characteristic abnormalities of metal homeostasis associated with Alzheimer's disease and other neurodegenerative disorders. For this purpose, serum samples are subjected to protein precipitation under non-denaturing conditions, taking special care for maintaining the integrity of metal-biomolecule bindings and for preventing species transformation, and then both the supernatant (low molecular mass fraction) and the precipitate (high molecular mass fraction) are analyzed by ICP-MS in order to determine the biodistribution of serum trace elements. This methodology is validated for 11 trace elements, including aluminum, cadmium, cobalt, chromium, copper, iron, manganese, molybdenum, selenium, vanadium, and zinc, in terms of sensitivity, selectivity, accuracy, and precision.

Altered Metal Homeostasis Associates with Inflammation, Oxidative Stress, Impaired Glucose Metabolism, and Dyslipidemia in the Crosstalk between Childhood Obesity and Insulin Resistance

“…For the analysis of the total metal contents, aliquots of plasma (150 µL) and erythrocyte (50 µL) samples were diluted to a final volume of 3 mL using an alkaline solution containing 2% 1-butanol ( w / v ), 0.05% EDTA ( w / v ), 0.05% Triton X-100 ( w / v ), and 1% NH 4 OH ( w / v ) [ 20 ]. Complementarily, samples were also subjected to protein precipitation under non-denaturing conditions for size-fractionation of metal species following the methodology optimized by González-Domínguez et al [ 21 , 22 ]. Briefly, 300 µL of cold acetone (−20 °C) was added dropwise to 150 µL of plasma, or 50 µL in the case of erythrocytes.…”

Circulatory Levels of Toxic Metals (Aluminum, Cadmium, Mercury, Lead) in Patients with Alzheimer’s Disease: A Quantitative Meta-Analysis and Systematic Review

“…Recent research suggests the importance of epigenetic mechanisms in defining the relationship between environmental exposures and AD [8]. Specifically, environmental toxic metals exposure has been implicated in AD pathogenesis [9]. Humans are exposed to toxic metals through a variety of sources, such as diet and occupational exposures [7].…”

“…If Hg accumulates in the brain beyond the ability of Selenoprotein P (SelP) to fully buffer its toxicity, Hg can cause oxidative stress and apoptosis in AD [14]. In addition, Pb and Cd cause a reduction in the brain content of acetylcholine, an important neurotransmitter closely related to the pathogenesis of AD [9,15].…”

Trace elements as potential modulators of puberty‐induced amelioration of oxidative stress and inflammation in childhood obesity

“…Thus, the accuracy was computed considering the concentrations detected in spiked and nonspiked samples by using the following formula: [100 × (concentration spiked − concentration nonspiked )/spiked concentration]. On the other hand, the fractionation method was validated using standard solutions of bovine serum albumin (BSA), as described elsewhere 26 . For this purpose, we prepared a 50 mg/mL aqueous solution of BSA containing copper and zinc, which was subjected to the above‐described protocol for protein precipitation under nondenaturing conditions.…”

“…On the other hand, the fractionation method was validated using standard solutions of bovine serum albumin (BSA), as described elsewhere. 26 For this purpose, we prepared a 50 mg/mL aqueous solution of BSA containing copper and zinc, which was subjected to the above-described protocol for protein precipitation under nondenaturing conditions. Then, multielemental analysis was performed in the resulting HMM and LMM fractions to check the integrity of metal-protein bindings during the extraction process (i.e., negligible release of copper and zinc into the LMM fraction).…”