Publications by authors named "Brandon Mahan"

The Alzheimer's disease (AD)-affected brain purges K with concurrently increasing serum K, suggesting brain-blood K transferal. Here, natural stable K isotope ratios-δ41K-of human serum samples were characterized in an AD biomarker pilot study (plus two paired Li-heparin and potassium ethylenediaminetetraacetic acid [K-EDTA] plasma samples). AD serum was found to have a significantly lower mean δ41K relative to controls.

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Aging is the main risk factor for Alzheimer's disease (AD). AD is linked to alterations in metal homeostasis and changes in stable metal isotopic composition can occur, possibly allowing the latter to serve as relevant biomarkers for potential AD diagnosis. Copper stable isotopes are used to investigate changes in Cu homeostasis associated with various diseases.

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The stable calcium (Ca) isotopes offer a minimally invasive method for assessing Ca balance in the body, providing a new avenue for research and clinical applications. In this study, we measured the Ca isotopic composition of soft tissues (brain, muscle, liver, and kidney), mineralized tissue (bone), and blood (plasma) from 10 mice (5 females and 5 males) with three different genetic backgrounds and same age (3 months old). The results reveal a distinctive Ca isotopic composition in different body compartments of mice, primally controlled by each compartment's unique Ca metabolism and genetic background, independent of sex.

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  • River sharks (Glyphis spp.) and some sawfish (Pristidae) utilize riverine habitats, but their long-term living patterns remain unclear.
  • The study examined the movements and elemental signatures of northern river shark and sawfish species, employing a technique called LA-ICP-MS on their vertebrae to assess their habitat use based on elemental ratios.
  • Findings revealed that barium indicates freshwater use, while lithium and strontium indicate marine use; both river shark species generally favor upper-estuarine environments, with evidence that parturition happens in freshwater for the largetooth sawfish.
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Potassium (K) is an essential electrolyte for cellular functions in living organisms, and disturbances in K+ homeostasis could lead to various chronic diseases (e.g. hypertension, cardiac disease, diabetes, and bone health).

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Natural stable metal isotopes have shown utility in differentiation between healthy and diseased brain states (e.g. Alzheimer's disease, AD).

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  • - Copper stable isotopes can help track changes in copper levels related to diseases like liver cirrhosis and cancer, but we need more data on how these isotopes are distributed in healthy organisms first
  • - A study examined copper isotopes in various organs (brain, liver, kidneys, etc.) of 14 mice and found that each organ has a unique isotope composition, with kidneys showing the highest levels
  • - Male and female mice show differences in copper concentrations, but genetic background doesn’t seem to influence the isotopic distribution; this study suggests stable copper isotopes could be useful for studying diseases that disrupt copper homeostasis
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  • The K-Pg boundary shows geochemical signs of extraterrestrial materials, but lacks evidence of volatilization, a process from large impacts.
  • Stable Zn isotopes effectively indicate volatility, where vaporization enhances heavy isotopes in remaining materials.
  • Analysis of Zn isotopes in K-Pg boundary sediments reveals heavier Zn values and lower concentrations, suggesting partial evaporation linked to the impact event, distinguishing it from volcanic influences or weathering effects.
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Introduction: Alzheimer's disease (AD) is neuropathologically marked by amyloid beta (Aβ) plaques and neurofibrillary tangles. Little is known about isotopic compositions of human AD brains. Here we study this in comparison with control subjects for copper and zinc.

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Biometals play a critical role in both the healthy and diseased brain's functioning. They accumulate in the normal aging brain, and are inherent to neurodegenerative disorders and their associated pathologies. A prominent example of this is the brain accumulation of metals such as Ca, Fe and Cu (and more ambiguously, Zn) associated with Alzheimer's disease (AD).

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Metallomics is a rapidly evolving field of bio-metal research that integrates techniques and perspectives from other "-omics" sciences (e.g. genomics, proteomics) and from research vocations further afield.

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The role of metals in biologic systems is manifold, and understanding their behaviour in bodily processes, especially those relating to neurodegenerative diseases, is at the forefront of medical science. The function(s) of metals - such as the transition metals - and their utility in both the diagnosis and treatment of diseases in human beings, is often examined via the characterization of their distribution in animal models, with porcine models considered exceptional proxies for human physiology. To this end, we have investigated the homeostatic distribution of numerous metals (Mg, K, Ca, Mn, Fe, Cu, Zn, Rb and Mo), the non-metal P, and Zn isotopes in the organs and blood (red blood cells, plasma) of Göttingen minipigs.

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Chondrites and their main components, chondrules, are our guides into the evolution of the Solar System. Investigating the history of chondrules, including their volatile element history and the prevailing conditions of their formation, has implications not only for the understanding of chondrule formation and evolution but for that of larger bodies such as the terrestrial planets. Here we have determined the bulk chemical composition-rare earth, refractory, main group, and volatile element contents-of a suite of chondrules previously dated using the Pb-Pb system.

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