The brain is a singular organ of unique biological complexity that serves as the command center for cognitive and motor function. As such, this specialized system also possesses a unique chemical composition and reactivity at the molecular level. In this regard, two vital distinguishing features of the brain are its requirements for the highest concentrations of metal ions in the body and the highest per-weight consumption of body oxygen. In humans, the brain accounts for only 2% of total body mass but consumes 20% of the oxygen that is taken in through respiration. As a consequence of high oxygen demand and cell complexity, distinctly high metal levels pervade all regions of the brain and central nervous system. Structural roles for metal ions in the brain and the body include the stabilization of biomolecules in static (e.g., Mg2+ for nucleic acid folds, Zn2+ in zinc-finger transcription factors) or dynamic (e.g., Na+ and K+ in ion channels, Ca2+ in neuronal cell signaling) modes, and catalytic roles for brain metal ions are also numerous and often of special demand.

Metals in Neurobiology: Probing Their Chemistry and Biology with Molecular Imaging

Copper toxicity, oxidative stress, and antioxidant nutrients.

The interplay between free radicals, antioxidants, and co-factors is important in maintaining health, aging and age-related diseases. Free radicals induce oxidative stress, which is balanced by the body’s endogenous antioxidant systems with an input from co-factors, and by the ingestion of exogenous antioxidants. If the generation of free radicals exceeds the protective effects of antioxidants, and some co-factors, this can cause oxidative damage which accumulates during the life cycle, and has been implicated in aging, and age dependent diseases such as cardiovascular disease, cancer, neurodegenerative disorders, and other chronic conditions. The life expectancy of the world population is increasing, and it is estimated that by 2025, 29% of the world population will be aged ≥60 years, and this will lead to an increase in the number of older people acquiring age-related chronic diseases. This will place greater financial burden on health services and high social cost for individuals and society. In order to acheive healthy aging the older people should be encouraged to acquire healthy life styles which should include diets rich in antioxidants. The aim of this review is to highlight the main themes from studies on free radicals, antioxidants and co-factors, and to propose an evidence-based strategy for healthy aging.

Studies on free radicals, antioxidants, and co-factors.

Zinc requirements and the risks and benefits of zinc supplementation

Acute toxicological effects of copper nanoparticles in vivo.

Copper absorption and retention in young men at three levels of dietary copper by use of the stable isotope 65Cu.

Copper absorption, excretion, and retention by young men consuming low dietary copper determined by using the stable isotope 65Cu

Copper status of young men consuming a low-copper diet

Molybdenum absorption, excretion, and retention studied with stable isotopes in young men during depletion and repletion.

Methods were developed to separate and purify Mo from biological samples and to measure isotopic ratios in 1 microgram of Mo. A magnetic sector, thermal ionization mass spectrometer was used with simultaneous collection of five isotopes. Isotopic ratios were corrected for mass fractionation by iterative normalization using the 96/98 ratio. Ion beam intensity was enhanced by using a double-filament configuration, loading samples onto evaporation filaments with silica gel and boric acid. A triple-isotope-dilution approach was used, so the method could be applied to two-tracer studies of Mo metabolism in human subjects. 94Mo was added to samples prior to purification to quantify the total Mo content of samples and to determine the amounts of enriched 97Mo and 100Mo appearing in urine and fecal samples of study participants. The three ratios, 94/98, 97/98, and 100/98, were determined with within-run precision of from 0.06 to 0.10% (RSD). Precision of the ratios between replicates was from 0.05 to 0.08%.

Judith R. Turnlund

Papers

Copper absorption and retention in young men at three levels of dietary copper by use of the stable isotope 65Cu.

Copper absorption, excretion, and retention by young men consuming low dietary copper determined by using the stable isotope 65Cu

Copper status of young men consuming a low-copper diet

Molybdenum absorption, excretion, and retention studied with stable isotopes in young men during depletion and repletion.

Isotope ratios of molybdenum determined by thermal ionization mass spectrometry for stable isotope studies of molybdenum metabolism in humans.