Instrumental neutron activation analysis, a technique for measurement of Se, Hg, Fe, Zn, K, Mn, Br, and the Hg:Se ratio in brain tissue samples with results from the Memory and Aging Project (MAP)

Mercury, selenium, and fatty acids in the axial muscle of largemouth bass: evaluating the influence of seasonal and sexual changes in fish condition and reproductive status

Largemouth bass (LMB, 265-475 mm) were collected to document whether changes in fish condition and reproductive status influenced the concentration of total mercury (Hg) and selenium (Se) in axial muscle by season and sex. The fatty acid (FA) composition of fish was also examined to describe seasonal and sexual differences and identify whether arachidonic acid (ARA) could be used as a biomarker of Hg toxicity. There was a trend for females to have lower (p < 0.062) Se concentrations than males. The concentration of Se for females during spring (mean ± SD, 686 ± 51 ng/g dw) was 15% lower than males (806 ± 67 ng/g dw). Lower Se concentrations in females than males continued through summer and fall. Concentration of Hg for females during spring (152 ± 39 ng/g ww) was also 59% lower than males (373 ± 303 ng/g ww), but the difference was not significant (p > 0.2). The percent of lipids was greatest in fall and winter (3%) and comprised primarily of omega-3 fatty acids (35 g/100 g lipid). Fish condition as measured by percent lipids and relative weight was negatively (p < 0.02) related to Hg concentration for females and males. Lipid content for both sexes was also positively (p < 0.05) related to the Se:Hg ratio. Relative weight was positively related to the Se:Hg ratio for females during all seasons (p = 0.014), but only during spring and summer for males (p < 0.007). A low Se:Hg value was associated with an elevation in ARA for both sexes and a reduced hepatosomatic index in males. Data suggested that females transferred muscle stores of Se and Hg to developing oocytes during spring. This study generates hypotheses regarding the physiological drivers of seasonal and sexual variability in Hg, Se, and FA in LMB that may be applicable to other species and have implications for fisheries health and management.

Unravelling neurological disorders through metallomics-based approaches

Understanding the biological process involving metals and biomolecules in the brain is essential for establishing the origin of neurological disorders, such as neurodegenerative and psychiatric diseases. From this perspective, this critical review presents recent advances in this topic, showing possible mechanisms involving the disruption of metal homeostasis and the pathogenesis of neurological disorders. We also discuss the main challenges observed in metallomics studies associated with neurological disorders, including those related to sample preparation and analyte quantification.

Selective Fluorometric Analysis of Hg(II) in Industrial Waste Water Samples

The highly selective and sensitive fluorometric method has been developed for trace level determination of Hg(II) is based on photo-induced electron transfer between rhodamine-6G dye and metal complex. Quenching in fluorescence intensity by fluorescence resonance energy transfer (FRET) is due to interaction between metal ion complex and dye. The fluorescence emitted was measured at 510 and 550 nm, for excitation and emission wavelengths respectively. Possible interferences present in water samples, which could affect the analytical response are studied and determined. The calibration graph was dynamically linear from 0.002 to 0.05 mgL^-1 of Hg(II) with limit of detection 7 × 10^-4 mgL^-1 and limit of quantitation 1.9 × 10^-3 mgL^-1. The Stern-Volmer constant (K_SV) calculated for the quenching of R-6G with Hg (II) was 8.47 Lmg^-1 s^-1 at optimized reaction conditions. The proposed FRET based fluorometric method was applied successfully in different industrial wastewater samples with satisfactory outcome.

Nearly Monodisperse Copper Selenide Nanoparticles for Recognition, Enrichment, and Sensing of Mercury Ions

In the current work, Cu(I)_1.28Cu(II)_0.36Se nanoparticles were synthesized via a simple procedure and were applied for the first time for recognition, adsorption, enrichment, and detection of Hg(II) ions. The experimental results show that 99.9% Hg(II) could be adsorbed by Cu(I)_1.28Cu(II)_0.36Se nanoparticles within just 30 s, and the Hg(II) concentration could be lowered down to a super-low level of 0.01 ppb. Cu(I)_1.28Cu(II)_0.36Se nanoparticles also demonstrate high selectivity to Hg(II) and Ag(I) among nine representative metal ions. The enrichment experiments show that Hg(II) of ultratrace concentration could be enriched significantly by Cu(I)_1.28Cu(II)_0.36Se nanoparticles, and thus, the detection limit of Hg(II) based on inductively coupled plasma emission spectroscopy-mass spectrometry would be pushed down by 2 orders of magnitude. These outstanding features of Cu(I)_1.28Cu(II)_0.36Se nanoparticles could be well accounted for in terms of the solubility product principle and the high affinity between selenium and mercury. Cu(I)_1.28Cu(II)_0.36Se nanoparticles were also found to have peroxidase-like activity, which could be inhibited by Hg(II) but not by Ag(I). This unique characteristic coupled with the solubility product principle successfully allows recognition and detection of Hg(II) even in the presence of Ag(I), which has a similar pK_sp to Hg(II). As a result, the qualitative and quantitative analyses of Hg(II) could be performed by the naked eye and UV-visible spectroscopy, respectively. The current results indicate that Cu(I)_1.28Cu(II)_0.36Se nanoparticles not only have great potential in various aspects of dealing with Hg(II) pollution but would also shed light on discovering new nanomaterials to address other heavy metal ions.

Brain Bromine Levels Associated with Alzheimer's Disease Neuropathology

BACKGROUND

Bromine is a naturally occurring element that is widely present in the human environment in various chemical forms primarily as flame retardants, pesticides, and water treatments.

OBJECTIVE

In this exploratory study, we investigated the association of brain bromine concentrations on Alzheimer's disease (AD) neuropathology, cerebral infarcts, and Lewy bodies.

METHODS

The study was conducted in 215 deceased participants of the Memory and Aging Project, a clinical-pathologic cohort study. Brain bromine levels were measured using instrumental neutron activation analysis. Multiple brain regions were assessed for diffuse and neuritic plaques, neurofibrillary tangles, cerebral macro-and microinfarcts, and Lewy bodies. Standardized measures of AD pathology (Braak, CERAD, NIA-Reagan, global AD pathology) were computed.

RESULTS

In linear regression models, the higher brain bromine levels were associated with more AD neuropathology (Braak (p trend = 0.01); CERAD (p trend = 0.02); NIA-Reagan (p trend = 0.02).

CONCLUSION

Bromine accumulation in the brain is associated with higher level of AD neuropathology. The potential deleterious effects of this element on AD need further exploration.