Metal toxicity, liver disease and neurodegeneration

Advancement of membrane separation technology for organic pollutant removal

In the face of growing global freshwater scarcity, the imperative to recycle and reuse water becomes increasingly apparent across industrial, agricultural, and domestic sectors. Eliminating a range of organic pollutants in wastewater, from pesticides to industrial byproducts, presents a formidable challenge. Among the potential solutions, membrane technologies emerge as promising contenders for treating diverse organic contaminants from industrial, agricultural, and household origins. This paper explores cutting-edge membrane-based approaches, including reverse osmosis, nanofiltration, ultrafiltration, microfiltration, gas separation membranes, and pervaporation. Each technology's efficacy in removing distinct organic pollutants while producing purified water is scrutinized. This review delves into membrane fouling, discussing its influencing factors and preventative strategies. It sheds light on the merits, limitations, and prospects of these various membrane techniques, contributing to the advancement of wastewater treatment. It advocates for future research in membrane technology with a focus on fouling control and the development of energy-efficient devices. Interdisciplinary collaboration among researchers, engineers, policymakers, and industry players is vital for shaping water purification innovation. Ongoing research and collaboration position us to fulfill the promise of accessible, clean water for all.

The emerging role of copper in depression

Copper (Cu) is an essential trace element in the brain and serves as an important cofactor for numerous enzymes involved in a wide range of biochemical processes including neurobehavioral, mitochondrial respiration, and antioxidant effects. Recent studies have demonstrated that copper dyshomeostasis is tightly associated with the development of depression by inducing oxidative stress and inflammatory responses. However, these findings have remained controversial so far. Cumulative studies have shown a positive association, while some other studies showed no association and even a negative association between serum/plasma copper level and depression. Based on these conflicted results, the association was speculated to be due to the clinical features of the population, stages of the disease, severity of copper excess, and types of specimens detected in these studies. In addition, there was an inverse association between dietary copper intake and depression. Furthermore, increasing copper intake could influence dietary zinc and iron intake to prevent and treat depression. Thus, copper supplementation may be a good measure to manage depression. This review provided a deeper understanding of the potential applicability of copper in the prevention and treatment of depression.

Dystonia and Parkinson's disease: Do they have a shared biology?

Parkinsonism and dystonia co-occur across many movement disorders and are most encountered in the setting of Parkinson's disease. Here we aim to explore the shared neurobiological underpinnings of dystonia and parkinsonism through the clinical lens of the conditions in which these movement disorders can be seen together. Foregrounding the discussion, we briefly review the circuits of the motor system and the neuroanatomical and neurophysiological aspects of motor control and highlight their relevance to the proposed pathophysiology of parkinsonism and dystonia. Insight into shared biology is then sought from dystonia occurring in PD and other forms of parkinsonism including those disorders in which both can be co-expressed simultaneously. We organize these within a biological schema along with important questions to be addressed in this space.

Spatio-temporal dynamics of water quality in river sources of drinking water in Uttarakhand with reference to human health

Any contamination in potable water leads to high risk on human health. Hence, it is inevitable to characterize water quality and assess temporal change with reference to human health. In this paper, nineteen water quality parameters from 50 sources of drinking water supply operated by state agency Uttarakhand Jal Sansthan (UJS) were analysed. The water samples were collected for pre-monsoon (May) and post-monsoon (November) seasons for the year 2010, 2011, 2018 and 2019. Multivariate analysis such as Pearson's correlation coefficient (r), K-mean, hierarchical clustering and principle component analysis (PCA) were applied to examine the drinking water quality at source sites. The strength of correlation among the parameters is reduced over the time. Cluster analysis provides six major hydro-chemical clusters in the study region. Clusters were compact during 2010-2011 and converted to overlapping structure in later period. The size of clusters was change from two clusters to six clusters during 2018-2019. These hydro-chemical clusters were examined through PCA and established six major hydro-chemical components of water quality. The physico-chemical parameters, namely, pH, alkalinity, TH, TDS, Na, K, Ca, Mg, Cl and SO₄, were in PC-1, the heavy metals in PC-3, turbidity in PC-4, TC in PC-5 and PC-6 is combination of turbidity, NO₃ and TC, whereas PC-2 was a mix of pH and Na and K salts. Study highlighted that the water quality has changed over the time due to runoff of plant debris, erosion, agricultural fertilizer, development activities and local geology hosts. Each PCs was mapped with associated human health issues. Result reveals that structures and pattern of PCs indicate several human health diseases over the later period with seasonal effects.

Non-invasive radionuclide imaging of trace metal trafficking in health and disease: "PET metallomics"

Several specific metallic elements must be present in the human body to maintain health and function. Maintaining the correct quantity (from trace to bulk) and location at the cell and tissue level is essential. The study of the biological role of metals has become known as metallomics. While quantities of metals in cells and tissues can be readily measured in biopsy and autopsy samples by destructive analytical techniques, their trafficking and its role in health and disease are poorly understood. Molecular imaging with radionuclides - positron emission tomography (PET) and single photon emission computed tomography (SPECT) - is emerging as a means to non-invasively study the acute trafficking of essential metals between organs, non-invasively and in real time, in health and disease. PET scanners are increasingly widely available in hospitals, and methods for producing radionuclides of some of the key essential metals are developing fast. This review summarises recent developments in radionuclide imaging technology that permit such investigations, describes the radiological and physicochemical properties of key radioisotopes of essential trace metals and useful analogues, and introduces current and potential future applications in preclinical and clinical investigations to study the biology of essential trace metals in health and disease.

The impacts of different anticoagulants and long-term frozen storage on multiple metal concentrations in peripheral blood: a comparative study

It is important but remains unclear whether ethylenediaminetetraacetic acid (EDTA) and sodium heparin anticoagulants have different impacts on the levels of various metals in peripheral blood after long-term frozen storage. The concentrations of 22 metals (Al, As, Ba, Ca, Cd, Cr, Co, Cu, Mn, Mg, Mo, Ni, Fe, Pb, Rb, Se, Sn, Sb, Sr, Ti, V, Zn) in whole blood, blood cells and plasma from 22 healthy participants were determined twice, 18 months apart, using inductively coupled plasma mass spectrometry (ICP-MS). The mean percentage error (MPE) and intraclass correlation coefficient (ICC) were calculated to evaluate the impact of the anticoagulants and long-term frozen storage on metal concentrations, respectively. The concentrations of Sb and Ba in whole blood, blood cells and plasma were significantly altered by EDTA and sodium heparin at two measurement timepoints (P < 0.05 and MPE > 80%). In EDTA tubes, the Ti and Ni concentrations in blood cells were changed significantly; and in heparin tubes, the concentrations of Ni and Mo in blood cells and Sb in plasma were also altered (P < 0.05 and MPE > 80%). The ICCs of 11 metals in whole blood, 15 metals in blood cells and 16 metals in plasma remained unchanged in EDTA tubes, and 16 metals in whole blood, 15 metals in blood cells and 17 metals in plasma remained unchanged in heparin tubes (ICC > 0.40). Our study suggested the use of EDTA tubes to determine Sb concentrations in peripheral blood and heparin tubes to determine Ba concentrations. Additionally, heparin tubes may be more suited for determining multiple metal concentrations in whole blood, whereas for blood cells and plasma either EDTA or heparin tubes could be used.

Copper, Iron, and Manganese Toxicity in Neuropsychiatric Conditions

Copper, manganese, and iron are vital elements required for the appropriate development and the general preservation of good health. Additionally, these essential metals play key roles in ensuring proper brain development and function. They also play vital roles in the central nervous system as significant cofactors for several enzymes, including the antioxidant enzyme superoxide dismutase (SOD) and other enzymes that take part in the creation and breakdown of neurotransmitters in the brain. An imbalance in the levels of these metals weakens the structural, regulatory, and catalytic roles of different enzymes, proteins, receptors, and transporters and is known to provoke the development of various neurological conditions through different mechanisms, such as via induction of oxidative stress, increased α-synuclein aggregation and fibril formation, and stimulation of microglial cells, thus resulting in inflammation and reduced production of metalloproteins. In the present review, the authors focus on neurological disorders with psychiatric signs associated with copper, iron, and manganese excess and the diagnosis and potential treatment of such disorders. In our review, we described diseases related to these metals, such as aceruloplasminaemia, neuroferritinopathy, pantothenate kinase-associated neurodegeneration (PKAN) and other very rare classical NBIA forms, manganism, attention-deficit/hyperactivity disorder (ADHD), ephedrone encephalopathy, HMNDYT1-SLC30A10 deficiency (HMNDYT1), HMNDYT2-SLC39A14 deficiency, CDG2N-SLC39A8 deficiency, hepatic encephalopathy, prion disease and “prion-like disease”, amyotrophic lateral sclerosis, Huntington’s disease, Friedreich’s ataxia, and depression.

Seleno-l-methionine suppresses copper-enhanced zinc-induced neuronal cell death via induction of glutathione peroxidase

Excessive zinc ion (Zn²⁺) release is induced in pathological situations and causes neuronal cell death. Previously, we have reported that copper ions (Cu²⁺) markedly exacerbated Zn²⁺-induced neuronal cell death by potentiating oxidative stress, the endoplasmic reticulum (ER) stress response, and the activation of the c-Jun amino-terminal kinase (JNK) signaling pathway. In contrast, selenium (Se), an essential trace element, and amino acids containing selenium (such as seleno-l-methionine) have been reported to inhibit stress-induced neuronal cell death and oxidative stress. Thus, we investigated the effect of seleno-l-methionine on Cu²⁺/Zn²⁺-induced neuronal cell death in GT1-7 cells. Seleno-l-methionine treatment clearly restored the Cu²⁺/Zn²⁺-induced decrease in the viable cell number and attenuated the Cu²⁺/Zn²⁺-induced cytotoxicity. Accordingly, the levels of ER stress-related factors (especially, CHOP and GADD34) and of phosphorylated JNK increased upon CuCl₂ and ZnCl₂ co-treatment, whereas pre-treatment with seleno-l-methionine significantly suppressed these upregulations. Analysis of reactive oxygen species (ROS) as upstream factors of these pathways revealed that Cu²⁺/Zn²⁺-induced ROS production was clearly suppressed by seleno-l-methionine treatment. Finally, we found that seleno-l-methionine induced the antioxidative protein, glutathione peroxidase. Taken together, our findings suggest that seleno-l-methionine suppresses Cu²⁺/Zn²⁺-induced neuronal cell death and oxidative stress via induction of glutathione peroxidase. Thus, we think that seleno-l-methionine may help prevent refractory neurological diseases.

Involvement of SAPK/JNK Signaling Pathway in Copper Enhanced Zinc-Induced Neuronal Cell Death

Zinc (Zn) plays an important role in many organisms in various physiological functions such as cell division, immune mechanisms and protein synthesis. However, excessive Zn release is induced in pathological situations and causes neuronal cell death. Previously, we reported that Cu ions (Cu2+) markedly exacerbates Zn2+-induced neuronal cell death by potentiating oxidative stress and the endoplasmic reticulum stress response. In contrast, the stress-activated protein kinase/c-Jun amino-terminal kinase (SAPK/JNK) signaling pathway is important in neuronal cell death. Thus, in this study, we focused on the SAPK/JNK signaling pathway and examined its involvement in Cu2+/Zn2+-induced neurotoxicity. Initially, we examined expression of factors involved in the SAPK/JNK signaling pathway. Accordingly, we found that phosphorylated (ie, active) forms of SAPK/JNK (p46 and p54) are increased by CuCl2 and ZnCl2 co-treatment in hypothalamic neuronal mouse cells (GT1-7 cells). Downstream factors of SAPK/JNK, phospho-c-Jun, and phospho-activating transcription factor 2 are also induced by CuCl2 and ZnCl2 co-treatment. Moreover, an inhibitor of the SAPK/JNK signaling pathway, SP600125, significantly suppressed neuronal cell death and activation of the SAPK/JNK signaling pathway induced by CuCl2 and ZnCl2 cotreatment. Finally, we examined involvement of oxidative stress in activation of the SAPK/JNK signaling pathway, and found that human serum albumin-thioredoxin fusion protein, an antioxidative protein, suppresses activation of the SAPK/JNK signaling pathway. On the basis of these results, our findings suggest that activation of ZnCl2-dependent SAPK/JNK signaling pathway is important in neuronal cell death, and CuCl2-induced oxidative stress triggers the activation of this pathway.

Neurologic Considerations and Complications Related to Liver Transplantation

Neurologic complications of surgery can be devastating. The authors review neurologic considerations and complications associated with liver transplantation and discuss strategies to prevent, identify, and treat such adverse outcomes in the perioperative period.

On-Demand Detaching Nanosystem for the Spatiotemporal Control of Cancer Theranostics

Engineering multiple theranostic modalities into a single nanoscale entity holds great potential to rejuvenate cancer treatments; however, enabling the sophisticated spatiotemporal control of each component for maximizing theranostic improvement and minimizing side effects concurrently remains a challenge. Herein, an intelligent detachable "nanorocket" is developed to sequentially manipulate and optimize multitheranostic processes for magnetic resonance-assisted ultrasound-drug combined therapy (MR-HIFU-Drug). The "nanorocket" is constructed by integrating multicomponent (MnCO₃, doxorubicin, silica) on the pH-sensitive CaCO₃ nanoparticles step by step via cation exchange and controlled heterogeneous nucleation, in which doxorubicin is encapsulated in both carbonates and silica component. The "nanorocket" can initiate sequential detachment in the acidic tumor microenvironment. Specifically, carbonates decompose instantly, releasing Mn²⁺ as the MR contrast agent and leaving hollow silica nanostructure behind as the HIFU synergistic agent. Consequently, burst release of drug is also triggered, further triggering the degradation of silica, which in turn regulates the slow release of drug from the silica matrix. Thus, efficient tumor inhibition is achieved by enhanced HIFU ablation and biphase release of doxorubicin with a stepwise clearance of Mn and Si. This work establishes a system for the systematic spatiotemporal dispatch of diverse theranostic components for the balance of efficacy and safety in cancer theranostics.

Assessment of 22 inorganic elements in human amniotic fluid: a cross-sectional study conducted in Canary Islands (Spain)

We conducted a cross-sectional study in the Hospital Universitario de Canarias (Tenerife, Canary Islands, Spain) measuring 22 inorganic elements in amniotic fluid (AF) samples obtained from 65 pregnant women. ICP-MS was used for quantification of inorganic elements. Newborn parameters at delivery were all within the normal range. Concentrations of all elements were detected in measurable amounts in AF. The concentration of elements was similar to those reported in the literature. The concentrations of the most dangerous heavy metals - Cd, Cr, Ni, Hg and Pb - were lower than those reported by other authors. This study demonstrates that toxic inorganic elements pass into and accumulate in AF. The presence of such pollutants in contact with developing embryos from the intrauterine period could exert adverse health effects that deserve future investigations.

Iron and manganese-related CNS toxicity: mechanisms, diagnosis and treatment

INTRODUCTION

Iron (Fe) and manganese (Mn) are essential nutrients for humans. They act as cofactors for a variety of enzymes. In the central nervous system (CNS), these two metals are involved in diverse neurological activities. Dyshomeostasis may interfere with the critical enzymatic activities, hence altering the neurophysiological status and resulting in neurological diseases. Areas covered: In this review, the authors cover the molecular mechanisms of Fe/Mn-induced toxicity and neurological diseases, as well as the diagnosis and potential treatment. Given that both Fe and Mn are abundant in the earth crust, nutritional deficiency is rare. In this review the authors focus on the neurological disorders associated with Mn and Fe overload. Expert commentary: Oxidative stress and mitochondrial dysfunction are the primary molecular mechanism that mediates Fe/Mn-induced neurotoxicity. Although increased Fe or Mn concentrations have been found in brain of patients, it remains controversial whether the elevated metal amounts are the primary cause or secondary consequence of neurological diseases. Currently, treatments are far from satisfactory, although chelation therapy can significantly decrease brain Fe and Mn levels. Studies to determine the primary cause and establish the molecular mechanism of toxicity may help to adapt more comprehensive and satisfactory treatments in the future.

Implications of Manganese in Chronic Acquired Hepatocerebral Degeneration

Neurological symptoms can be one of the over-riding symptoms in patients with liver cirrhosis. Patients can present with subtle changes in mood or neurological function due to hepatic encephalopathy (HE), to more severe presentations including stupor and coma. While HE, in its severe form, can be clinically easy to diagnose, more subtle forms may be more difficult to recognize. Other neurological diseases may indeed be overlooked in the context of cirrhosis or confuse the physician regarding the diagnosis. Chronic acquired hepatocerebral degeneration (CAHD) is an uncommon problem occurring in patients with cirrhosis characterised by a Parkinsonian-like neurological presentation with damage to the brain secondary to manganese (Mn) deposition. Here we describe a case of a patient with a neurological presentation of liver disease with a review of the current CAHD literature. In conclusion, CAHD is a rare condition occurring in liver cirrhosis that should always be considered in patients with neurological manifestations of chronic liver disease.

State of the art of management of hepatic myelopathy

Hepatic myelopathy (HM) is characterized by progressive weakness and spasticity of the lower extremities, which is a severe spinal cord involvement rarely occurring in patients with cirrhosis or other chronic liver diseases. The diagnosis is assigned after the exclusion of other clinical entities leading to spastic paraparesis. Liver transplantation represents a potentially treatment for HM in early stage.

Zebrafish slc30a10 deficiency revealed a novel compensatory mechanism of Atp2c1 in maintaining manganese homeostasis

Recent studies found that mutations in the human SLC30A10 gene, which encodes a manganese (Mn) efflux transporter, are associated with hypermanganesemia with dystonia, polycythemia, and cirrhosis (HMDPC). However, the relationship between Mn metabolism and HMDPC is poorly understood, and no specific treatments are available for this disorder. Here, we generated two zebrafish slc30a10 mutant lines using the CRISPR/Cas9 system. Compared to wild-type animals, mutant adult animals developed significantly higher systemic Mn levels, and Mn accumulated in the brain and liver of mutant embryos in response to exogenous Mn. Interestingly, slc30a10 mutants developed neurological deficits in adulthood, as well as environmental Mn-induced manganism in the embryonic stage; moreover, mutant animals had impaired dopaminergic and GABAergic signaling. Finally, mutant animals developed steatosis, liver fibrosis, and polycythemia accompanied by increased epo expression. This phenotype was rescued partially by EDTA- CaNa₂ chelation therapy and iron supplementation. Interestingly, prior to the onset of slc30a10 expression, expressing ATP2C1 (ATPase secretory pathway Ca²⁺ transporting 1) protected mutant embryos from Mn exposure, suggesting a compensatory role for Atp2c1 in the absence of Slc30a10. Notably, expressing either wild-type or mutant forms of SLC30A10 was sufficient to inhibit the effect of ATP2C1 in response to Mn challenge in both zebrafish embryos and HeLa cells. These findings suggest that either activating ATP2C1 or restoring the Mn-induced trafficking of ATP2C1 can reduce Mn accumulation, providing a possible target for treating HMDPC.

Impaired function of the manganese transporter SLC30A10 has been implicated in HMDPC (hypermanganesemia with dystonia, polycythemia, and cirrhosis), an early-onset metabolic disorder clinically characterized by increased systemic Mn levels, neurological impairment, polycythemia, and hepatic injury. No specific treatment is currently available for HMDPC. Moreover, the mechanisms that underlie Mn metabolism are poorly understood, thereby hindering the development of effective treatments. To investigate the physiological processes underlying Mn metabolism and to develop new disease models of HMDPC, we generated two zebrafish slc30a10 mutant lines using the CRISPR/Cas9 system and found that these mutants develop clinical deficits typically associated with HMDPC. Furthermore, we identified a putative compensatory role for ATP2C1 in the absence of SLC30A10 with respect to modulating Mn metabolism. These findings provide a valuable tool for investigating the role of manganese dysregulation in neurological degenerative diseases and which can be used to develop new pharmacological approaches for managing Mn accumulation.

Neuro-Preventive Effect and Elevation of Cellular Adenosine Triphosphate by PUFAs from Pteleiosis suberosa Stem Bark on Mercury Sub-Acute Exposed Rats

OBJECTIVES

Occupational/industrial exposure and experimental intoxication of mercury can produce neurological effects but Pteleiosis suberosa stem bark extract (PTSSBE) might be useful in the treatment of brain disorders because it's anti-ulcer, anti-inflammatory and antioxidant effects had been documented.

METHODS

The present study was therefore designed to investigate some phenolic constituents, evaluate its antioxidant properties and examine its reversal effects of PTSSBE on sub-acute mercury-induced brain toxicity. Rats were divided into five groups of 10 animals each. Group I was given distilled water; group II, III, IV and V was orally administered with mercury at a dose of 3.75 mg/kg body weight. Group III, IV and V were co-treated with PTSSBE of 25, 50 and 100 mg/ kg body weight respectively, for 10 days.

RESULTS

The results revealed that the stem bark extract exhibited high presence of antioxidants. Experimental exposure of rats to mercury significantly decreased the activities of catalase (CAT), lactate dehydrogenase (LDH), and the level of reduced glutathione (GSH), while the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and the formation of malondialdehyde (MDA) were increased. These effects were reversed by co-administration with PTSSBE in mercury-induced brain toxicity in rats.

CONCLUSION

The protective effects of Pteleiosis suberosa, during mercury exposure suggest that these phenolics and PUFAs may be helpful in treating neurological disorders and other related cerebral toxicity implicated in depleted cellular ATP and oxidative stress.

Recent Updates on Acquired Hepatocerebral Degeneration

BACKGROUND

Acquired hepatocerebral degeneration (AHD) refers to a chronic neurological syndrome in patients with advanced hepatobiliary diseases. This comprehensive review focuses on the pathomechanism and neuroimaging findings in AHD.

METHODS

A PubMed search was performed using the terms "acquired hepatocerebral degeneration," "chronic hepatocerebral degeneration," "Non-Wilsonian hepatocerebral degeneration," "cirrhosis-related parkinsonism," and "manganese and liver disease."

RESULTS

Multiple mechanisms involving the accumulation of toxic substances such as ammonia or manganese and neuroinflammation may lead to widespread neurodegeneration in AHD. Clinical characteristics include movement disorders, mainly parkinsonism and ataxia-plus syndrome, as well as cognitive impairment with psychiatric features. Neuroimaging studies of AHD with parkinsonism show hyperintensity in the bilateral globus pallidus on T1-weighted magnetic resonance images, whereas molecular imaging of the presynaptic dopaminergic system shows variable findings. Ataxia-plus syndrome in AHD may demonstrate high-signal lesions in the middle cerebellar peduncles on T2-weighted images.

DISCUSSION

Future studies are needed to elucidate the exact pathomechanism and neuroimaging findings of this heterogeneous syndrome.

Effects of manganese exposure on visuoperception and visual memory in schoolchildren

BACKGROUND

Manganese (Mn) is an essential metal involved in multiple physiological functions. Environmental exposure to airborne Mn is associated with neurocognitive deficits in humans. Children, whose nervous system is in development, are particularly susceptible to Mn neurotoxicity.

OBJECTIVE

The objective of this study was to assess the association between Mn environmental exposure, and effects on visuoperception and visual memory in schoolchildren.

METHODS

We assessed schoolchildren between 7 and 11 years old, with similar socioeconomic status, from the mining district of Molango (n=148) and Agua Blanca (n=119, non-mining area) in Hidalgo state, Mexico. The Rey-Osterrieth Complex Figure (ROCF) test was used to assess visuoperception and short-term visual memory. Hair manganese (MnH) concentrations were determined. Linear regression models were constructed to estimate the associations between MnH and ROCF scores, adjusted for potential confounders.

RESULTS

The geometric mean MnH was nine times higher in schoolchildren from the Mn mining area (5.25μg/g) than in schoolchildren from the non-mining area (0.55μg/g). For the ROCF Copy trial, MnH was significantly associated with an increase in distortion errors (tangency, closure), angle errors, overtracing (partial overtracing). In the Immediate Recall trial, MnH was significantly associated with increased overtracing (partial overtracing) and omissions, and negatively associated with the number of perceptual drawn units, total score and percentage immediate recall.

CONCLUSIONS

MnH is associated with alterations in visuoperception and short-term visual memory in schoolchildren exposed to airborne Mn.

Hypermanganesemia with Dystonia, Polycythemia and Cirrhosis (HMDPC) due to mutation in the SLC30A10 gene

Manganese (Mn) is an essential element for metabolic pathways but it can be toxic when present in excessive amounts in the body. Hypermanganesemia along with dystonia, polycythemia, characteristic MRI brain findings in the basal ganglia, and chronic liver disease are the hallmarks of an inherited Mn transporter defect due to mutations in the SLC30A10 gene. We are reporting three siblings who presented with features of dystonia, polycythemia, MRI brain showing basal ganglia hyperintensity on T1 weighted images and chronic liver disease. Blood Mn levels were markedly elevated in the affected patients. Mutation analysis of DNA samples of the affected children confirmed a homozygous missense mutation in SLC30A10. Chelation therapy with intravenous disodium calcium edetate was started in two siblings and led to a marked decrease in whole blood Mn. Oral Penicillamine was later added to the therapy which further improved blood Mn levels. This is a rare disorder and is one of the potentially treatable inherited metal storage disorders. It can be fatal if left untreated. Penicillamine may be an effective alternative to disodium calcium edetate.

The effect of high dose oral manganese exposure on copper, iron and zinc levels in rats

Manganese is an essential dietary nutrient and trace element with important roles in mammalian development, metabolism, and antioxidant defense. In healthy individuals, gastrointestinal absorption and hepatobiliary excretion are tightly regulated to maintain systemic manganese concentrations at physiologic levels. Interactions of manganese with other essential metals following high dose ingestion are incompletely understood. We previously reported that gavage manganese exposure in rats resulted in higher tissue manganese concentrations when compared with equivalent dietary or drinking water manganese exposures. In this study, we performed follow-up evaluations to determine whether oral manganese exposure perturbs iron, copper, or zinc tissue concentrations. Rats were exposed to a control diet with 10 ppm manganese or dietary, drinking water, or gavage exposure to approximately 11.1 mg manganese/kg body weight/day for 7 or 61 exposure days. While manganese exposure affected levels of all metals, particularly in the frontal cortex and liver, copper levels were most prominently affected. This result suggests an under-appreciated effect of manganese exposure on copper homeostasis which may contribute to our understanding of the pathophysiology of manganese toxicity.

Copper disrupts S-nitrosothiol signaling in activated BV2 microglia

Microglia, the primary resident immune cells of the central nervous system (CNS), responds rapidly to pathogens and injury by secreting immune mediators including nitric oxide (NO). The reaction of NO with the anti-oxidant glutathione forms S-nitrosoglutathione (GSNO), the major pool of biologic NO in the body. GSNO is degraded by GSNO reductase (GSNOR). Recently, we have shown that copper (Cu(I)) inhibits the release of NO in lipopolysaccharide (LPS)-stimulated BV2 microglia and induces BV2 microglia to acquire a mixed a profile with both pro- and anti-inflammatory characteristics. Since GSNOR is the critical enzyme in GSNO metabolism, we sought to determine whether Cu(I) affects GSNOR activity and S-nitrosothiol (SNO) accumulation in activated BV2 microglia. Our results show that GSNOR protein expression is reduced by Cu(I) treatment in LPS-stimulated BV2 microglia. Our results also show a decrease in S-nitrosothiol content despite a reduced GSNOR expression. This effect is most likely due to Cu(I) reacting with the central thiol of the SNO bond resulting in the degradation of SNO. A dose of 1 μM Cu(I) did not affect SNO protein accumulation in LPS-stimulated BV2 microglia, however, a dose of 100 μM Cu(I) inhibited SNO protein in accordance with inhibition of S-nitrosothiols. These data provide direct evidence that Cu(I) disrupts S-nitrosothiol homeostasis and NO metabolism, and, thus, provide new insights into the mechanisms involved in microglia-mediated-CNS disorders.

Altered metal metabolism in patients with HCV-related cirrhosis and hepatic encephalopathy

Dysfunctional metal homeostasis contributes to oxidative stress and neuronal damage. These have been implicated in hepatic encephalopathy pathogenesis. To investigate whether altered metal metabolism is associated with hepatic encephalopathy. Twenty-one controls and 34 HCV-cirrhotic patients (ENC/NEC patients according to presence/absence of previous overt episodes of hepatic encephalopathy) and a control group were studied. Serum iron, copper, ceruloplasmin, ceruloplasmin activity, transferrin, and ceruloplasmin/transferrin ratio were determined. Neuropsychological tests were performed by the repeatable battery of neuropsychological status. Magnetic resonance assessed basal ganglia volumes and metal deposition (pallidal index and T2*). Cirrhotic patients performed worse than controls at cognitive tests, especially ENC patients,. At biochemical analysis copper concentrations, ceruloplasmin activity and transferrin levels were lower in ENC than in NEC patients and controls (p < 0.05 and p < 0.01, respectively). Ceruloplasmin/transferrin ratio was higher in ENC compared to NEC patients (p < 0.05), and controls (p < 0.01). By brain magnetic resonance, ENC patients showed reduced caudate and globus pallidus volumes compared to controls (p < 0.05), and ENC and NEC patients an increased pallidal index compared to controls (p < 0.01). In ENC patients, ceruloplasmin activity correlated with caudate volume and pallidal index (ρ = 0.773 and ρ = -0.683, p < 0.05). Altered metal metabolism likely contributes to cirrhotic hepatic encephalopathy.

Glial Asthenia and Functional Paralysis: A New Perspective on Neurodegeneration and Alzheimer's Disease

Neuroglia are represented by several population of cells heterogeneous in structure and function that provide for the homeostasis of the brain and the spinal cord. Neuroglial cells are also central for neuroprotection and defence of the central nervous system against exo- and endogenous insults. At the early stages of neurodegenerative diseases including Alzheimer's disease neuroglial cells become asthenic and lose some of their homeostatic, neuroprotective, and defensive capabilities. Astroglial reactivity, for example, correlates with preservation of cognitive function in patients with mild cognitive impairment and prodromal Alzheimer's disease. Here, we overview the experimental data indicating glial paralysis in neurodegeneration and argue that loss of glial function is fundamental for defining the progression of neurodegenerative diseases.

Manganese-induced atypical parkinsonism is associated with altered Basal Ganglia activity and changes in tissue levels of monoamines in the rat

Manganese neurotoxicity is associated with motor and cognitive disturbances known as Manganism. However, the mechanisms underlying these deficits remain unknown. Here we investigated the effects of manganese intoxication on motor and non-motor parkinsonian-like deficits such as locomotor activity, motor coordination, anxiety and “depressive-like” behaviors. Then, we studied the impact of this intoxication on the neuronal activity, the globus pallidus (GP) and subthalamic nucleus (STN). At the end of experiments, post-mortem tissue level of the three monoamines (dopamine, norepinephrine and serotonin) has been determined. The experiments were carried out in adult Sprague-Dawley rats, daily treated with MnCl₂ (10 mg/kg/, i.p.) for 5 weeks. We show that manganese progressively reduced locomotor activity as well as motor coordination in parallel with the manifestation of anxiety and “depressive-like” behaviors. Electrophysiological results show that, while majority of GP and STN neurons discharged regularly in controls, manganese increased the number of GP and STN neurons discharging irregularly and/or with bursts. Biochemical results show that manganese significantly decreased tissue levels of norepinephrine and serotonin with increased metabolism of dopamine in the striatum. Our data provide evidence that manganese intoxication is associated with impaired neurotransmission of monoaminergic systems, which is at the origin of changes in basal ganglia neuronal activity and the manifestation of motor and non-motor deficits similar to those observed in atypical Parkinsonism.

Chelating polymeric beads as potential therapeutics for Wilson's disease

Wilson's disease is a genetic disorder caused by a malfunction of ATPase 7B that leads to high accumulation of copper in the organism and consequent toxic effects. We propose a gentle therapy to eliminate the excessive copper content with oral administration of insoluble non-resorbable polymer sorbents containing selective chelating groups for copper(II). Polymeric beads with the chelating agents triethylenetetramine, N,N-di(2-pyridylmethyl)amine, and 8-hydroxyquinoline (8HQB) were investigated. In a preliminary copper uptake experiment, we found that 8HQB significantly reduced copper uptake (using copper-64 as a radiotracer) after oral administration in Wistar rats. Furthermore, we measured organ radioactivity in rats to demonstrate that 8HQB radiolabelled with iodine-125 is not absorbed from the gastrointestinal tract after oral administration. Non-resorbability and the blockade of copper uptake were also confirmed with small animal imaging (PET/CT) in mice. In a long-term experiment with Wistar rats fed a diet containing the polymers, we have found that there were no signs of polymer toxicity and the addition of polymers to the diet led to a significant reduction in the copper contents in the kidneys, brains, and livers of the rats. We have shown that polymers containing specific ligands could potentially be novel therapeutics for Wilson's disease.

Recent discoveries on the functions of astrocytes in the copper homeostasis of the brain: a brief update

In the last two decades, there has been widespread acknowledgment of the pivotal role played by astrocytes in diverse aspects of central nervous system functioning. Astrocytes are crucial for the homeostasis of the copper in the central nervous system as evident by its proficiency in acquisition, trafficking, and export of copper. Moreover, the imbalance in copper homeostasis and impairment in astrocyte functioning are increasingly being recognized as an important contributing factor in the development of neurodegeneration and cognitive waning. In this review, we discuss the most recent advances in the field of copper homeostasis in astrocytes along with briefly outlining the copper dyshomeostasis associated hepatocerebral and neurodegenerative diseases.

Copper toxicity induced hepatocerebral and neurodegenerative diseases: an urgent need for prognostic biomarkers

Copper (Cu) has been the subject of intensive research over several decades as numerous evidence robustly support the involvement of excess Cu induced neurotoxicity in hepatocerebral (Wilson's disease) and neurodegenerative disorders (especially Alzheimer's disease and Parkinson's disease); notwithstanding, the ideal Cu neurotoxicity biomarker/s for early prognosis remains elusive. Non-ceruloplasmin bound Cu is a biological marker of Wilson's disease and recent studies have shown that its levels are also increased in Alzheimer's disease. Copper chaperone for superoxide dismutase seems to be the other most promising biomarker of Cu toxicity (subject to its validation). Serum/plasma Cu, urine Cu and ceruloplasmin concentrations, most widely used laboratory indicators to diagnose Wilson's disease, are not specific for Cu excess milieu as these are also influenced by age, sex, inflammation and hormonal status. High inter-individual variability, nonexistence of standardized assays and non-specificity limit the use of other cuproenzymes as biomarkers of Cu neurotoxicity. The majority of Cu neurotoxicity biomarker research has focused in plasma/serum where other factors including inflammation, oxidative stress, dietary and environmental factors influence the Cu condition being studied. Proteomics study of cerebrospinal fluid, due to its high specificity and sensitivity represents an alternative approach to study early peripheral Cu neurotoxicity biomarker/s in experimental animals. In addition, network biology, transcriptomics in conjunction with novel in vivo Cu imaging techniques allow us to explore other potential candidates and propose new targets to be studied for chronic Cu neurotoxicity biomarker/s, and for possible therapeutic interventions.

The effect of iron-vitamin C co-supplementation on biomarkers of oxidative stress in iron-deficient female youth

There is no study that assessed the effect of co-supplementation of iron and vitamin C on biomarkers of oxidative stress in non-anemic iron-deficient females. We investigated the effects of iron vs. iron + vitamin C co-supplementation on biomarkers of oxidative stress in iron-deficient girls. In a double-blind randomized controlled clinical trial, performed among 60 non-anemic iron-deficient girls, participants were randomly assigned to receive either 50 mg/day elemental iron supplements or 50 mg/day elemental iron + 500 mg/day ascorbic acid for 12 weeks. Fasting blood samples were taken at baseline, weeks 6 and 12 for assessment of biomarkers of oxidative stress. Compared with the baseline levels, both iron and iron + vitamin C supplementation resulted in a significant reduction in serum malondialdehyde (MDA) levels (P time < 0.001) and remarkable elevation in serum total antioxidant capacity (TAC; P time < 0.001) and vitamin C levels (P time = 0.001); however, comparing the two groups we failed to find an additional effect of iron + vitamin C supplementation to that of iron alone on serum TAC and MDA levels (P group was not statistically significant). Iron + vitamin C supplementation influenced serum vitamin C levels much more than that by iron alone (P group < 0.01). We also found a significant interaction term between time and group about serum vitamin C levels while this interaction was not significant about serum TAC and MDA levels. In conclusion, we found that iron supplementation with/without vitamin C improve biomarkers of oxidative stress among non-anemic iron-deficient females and may strengthen the antioxidant defense system by decreasing reactive oxygen species. Co-supplementation of iron + vitamin C has no further effect on oxidative stress compared with iron alone.

Does dietary copper supplementation enhance or diminish PCB126 toxicity in the rodent liver?

Copper is essential for the function of the mitochondrial electron transport chain and several antioxidant proteins. However, in its free form copper can participate in Fenton-like reactions that produce reactive hydroxyl radicals. Aryl-hydrocarbon receptor (AhR) agonists, including the most potent polychlorinated biphenyl (PCB) congener, 3,3',4,4',5-pentachlorobiphenyl (PCB126), increase copper levels in rodent livers. This is accompanied by biochemical and toxic changes. To assess the involvement of copper in PCB toxicity, male Sprague-Dawley rats were fed an AIN-93G diet with differing dietary copper levels: low (2 ppm), adequate (6 ppm), and high (10 ppm). After three weeks, rats from each group were given a single ip injection of corn oil (control), 1, or 5 μmol/kg body weight PCB126. Two weeks following injections, biochemical and morphological markers of hepatic toxicity, trace metal status, and hepatic gene expression of metalloproteins were evaluated. Increasing dietary copper was associated with elevated tissue levels of copper and ceruloplasmin. In the livers of PCB126-treated rats, the hallmark signs of AhR activation were present, including increased cytochrome P450 and lipid levels and decreased glutathione. In addition, a doubling of hepatic copper levels was seen, and overall metal homeostasis was disturbed, resulting in decreased hepatic selenium, manganese, zinc, and iron. Expression of key metalloproteins was either decreased (cytochrome c oxidase), unchanged (ceruloplasmin and CuZnSOD), or increased (tyrosinase and metallothioneins 1 and 2) with exposure to PCB126. Increases in metallothionein may contribute/reflect the increased copper seen. Alterations in dietary copper did not amplify or abrogate the hepatic toxicity of PCB126. PCB126 toxicity, i.e., oxidative stress and steatosis, is clearly associated with disturbed metal homeostasis. Understanding the mechanisms of this disturbance may provide tools to prevent liver toxicity by other AhR agonists.

Interaction of occupational manganese exposure and alcohol drinking aggravates the increase of liver enzyme concentrations from a cross-sectional study in China

BACKGROUND

Over exposure to manganese (Mn) can damage the human central nervous system and potentially cause liver toxicity. Alcohol drinking is also one of the well-known harmful factors to hepatic organism. The interaction between Mn exposure and alcohol consumption to liver function was investigated in this study.

METHODS

A total of 1112 on-the-spot workers were included in the cross-sectional survey from a large scale of manganese exposed workers healthy cohort (MEWHC) in a ferro-manganese refinery company. A questionnaire was used to collect the demographic information, occupational history, and alcohol drinking habits. Occupational health examination was carried out for each worker. The five key serum indices, including total bilirubin (TBILI), direct bilirubin (DBILI), indirect bilirubin (IBILI), alanine transaminase (ALT), and aspartate transaminase (AST), were determined to evaluate the liver function of each subject.

RESULTS

Workers exposed to high levels of Mn had significantly elevated serum concentrations of liver enzymes (DBILI: 3.84±1.20 μmol/L, ALT: 27.04±19.12 IU/L, and AST: 29.96±16.68 IU/L), when compared to those in the low-exposure group (DBIL: 3.54±0.85 μmol/L, ALT: 20.38±10.97 IU/L, and AST: 26.39±8.07 IU/L), all P<0.01. These serum indices had a significantly increasing trend with the elevation of Mn exposure level (Ptrend <0.01). In addition, the workers with alcohol drinking also showed higher concentrations of liver enzymes than those non-drinkers, especially, and there was significant interaction between Mn exposure and alcohol consumption in terms of these three indices (P<0.001).

CONCLUSIONS

Occupational exposure to Mn can lead to a dose-dependent increase of liver enzyme concentrations, and interact with alcohol drinking to potentially aggravate the liver damage. It will be important for Mn exposed workers to control drinking and also assess liver function in the occupational health examination.

Biometals in rare neurodegenerative disorders of childhood

Copper, iron, and zinc are just three of the main biometals critical for correct functioning of the central nervous system (CNS). They have diverse roles in many functional processes including but not limited to enzyme catalysis, protein stabilization, and energy production. The range of metal concentrations within the body is tightly regulated and when the balance is perturbed, debilitating effects ensue. Homeostasis of brain biometals is mainly controlled by various metal transporters and metal sequestering proteins. The biological roles of biometals are vastly reviewed in the literature with a large focus on the connection to neurological conditions associated with ageing. Biometals are also implicated in a variety of debilitating inherited childhood disorders, some of which arise soon following birth or as the child progresses into early adulthood. This review acts to highlight what we know about biometals in childhood neurological disorders such as Wilson's disease (WD), Menkes disease (MD), neuronal ceroid lipofuscinoses (NCLs), and neurodegeneration with brain iron accumulation (NBIA). Also discussed are some of the animal models available to determine the pathological mechanisms in these childhood disorders, which we hope will aid in our understanding of the role of biometals in disease and in attaining possible therapeutics in the future.

Dystonia with brain manganese accumulation resulting from SLC30A10 mutations: a new treatable disorder

Background

The first gene causing early-onset generalized dystonia with brain manganese accumulation has recently been identified. Mutations in the SLC30A10 gene, encoding a manganese transporter, cause a syndrome of hepatic cirrhosis, dystonia, polycythemia, and hypermanganesemia.

Methods

We present 10-year longitudinal clinical features, MRI data, and treatment response to chelation therapy of the originally described patient with a proven homozygous mutation in SLC30A10.

Results

The patient presented with early-onset generalized dystonia and mild hyperbilirubinemia accompanied by elevated whole-blood manganese levels. T1-sequences in MRI showed hyperintensities in the basal ganglia and cerebellum, characteristic of manganese deposition. Treatment with intravenous disodium calcium edetate led to clinical improvement and reduction of hyperintensities in brain imaging.

Conclusions

We wish to highlight this rare disorder, which, together with Wilson's disease, is the only potentially treatable inherited metal storage disorder to date, that otherwise can be fatal as a result of complications of cirrhosis. © 2012 Movement Disorder Society

Mutations in SLC30A10 cause parkinsonism and dystonia with hypermanganesemia, polycythemia, and chronic liver disease

Manganese is essential for several metabolic pathways but becomes toxic in excessive amounts. Manganese levels in the body are therefore tightly regulated, but the responsible protein(s) remain incompletely known. We studied two consanguineous families with neurologic disorders including juvenile-onset dystonia, adult-onset parkinsonism, severe hypermanganesemia, polycythemia, and chronic hepatic disease, including steatosis and cirrhosis. We localized the genetic defect by homozygosity mapping and then identified two different homozygous frameshift SLC30A10 mutations, segregating with disease. SLC30A10 is highly expressed in the liver and brain, including in the basal ganglia. Its encoded protein belongs to a large family of membrane transporters, mediating the efflux of divalent cations from the cytosol. We show the localization of SLC30A10 in normal human liver and nervous system, and its depletion in liver from one affected individual. Our in silico analyses suggest that SLC30A10 possesses substrate specificity different from its closest (zinc-transporting) homologs. We also show that the expression of SLC30A10 and the levels of the encoded protein are markedly induced by manganese in vitro. The phenotype associated with SLC30A10 mutations is broad, including neurologic, hepatic, and hematologic disturbances. Intrafamilial phenotypic variability is also present. Chelation therapy can normalize the manganesemia, leading to marked clinical improvements. In conclusion, we show that SLC30A10 mutations cause a treatable recessive disease with pleomorphic phenotype, and provide compelling evidence that SLC30A10 plays a pivotal role in manganese transport. This work has broad implications for understanding of the manganese biology and pathophysiology in multiple human organs.

Gold-containing indoles as anticancer agents that potentiate the cytotoxic effects of ionizing radiation

This report describes the design and application of several distinct gold-containing indoles as anticancer agents. When used individually, all gold-bearing compounds display cytostatic effects against leukemia and adherent cancer cell lines. However, two gold-bearing indoles show unique behavior by increasing the cytotoxic effects of clinically relevant levels of ionizing radiation. Quantifying the amount of DNA damage demonstrates that each gold-indole enhances apoptosis by inhibiting DNA repair. Both Au(I)-indoles were tested for inhibitory effects against various cellular targets including thioredoxin reductase, a known target of several gold compounds, and various ATP-dependent kinases. While neither compound significantly inhibits the activity of thioreoxin reductase, both showed inhibitory effects against several kinases associated with cancer initiation and progression. The inhibition of these kinases provides a possible mechanism for the ability of these Au(I)-indoles to potentiate the cytotoxic effects of ionizing radiation. Clinical applications of combining Au(I)-indoles with ionizing radiation are discussed as a new strategy to achieve chemosensitization of cancer cells.

Acquired hepatocerebral degeneration and hepatic encephalopathy: correlations and variety of clinical presentations in overt and subclinical liver disease

Acquired hepatocerebral degeneration (AHD) and hepatolenticular degeneration can have similar clinical presentations, but when a chronic liver disease and atypical motor findings coexist, the distinction between AHD and hepatic encephalopathy (HE) can be even more complicated. We describe three cases of AHD (two having HE) with different neuroimaging findings, distinct hepatic diseases and similar motor presentations, all presenting chronic arterial hypertension and weight loss before the disease manifestations. The diagnosis and physiopathology are commented upon and compared with previous reports. In conclusion, there are many correlations among HE, hepatolenticular degeneration and AHD, but the overlapping of AHD and HE could be more common depending on the clinical knowledge and diagnostic criteria adopted for each condition. Since AHD is not considered a priority that affects the liver transplant list, the prognosis in AHD patients remains poor, and flow interruption in portosystemic shunts must always be taken into account.

Impaired hepatic function and central dopaminergic denervation in a rodent model of Parkinson's disease: a self-perpetuating crosstalk?

In Parkinson's disease (PD), aside from the central lesion, involvement of visceral organs has been proposed as part of the complex clinical picture of the disease. The issue is still poorly understood and relatively unexplored. In this study we used a classic rodent model of nigrostriatal degeneration, induced by the intrastriatal injection of 6-hydroxydopamine (6-OHDA), to investigate whether and how a PD-like central dopaminergic denervation may influence hepatic functions. Rats received an intrastriatal injection of 6-OHDA or saline (sham), and blood, cerebrospinal fluid, liver and brain samples were obtained for up to 8 weeks after surgery. Specimens were analyzed for changes in cytokine and thyroid hormone levels, as well as liver mitochondrial alterations. Hepatic mitochondria isolated from animals bearing extended nigrostriatal lesion displayed increased ROS production, while membrane potential (ΔΨ) and ATP production were significantly decreased. Reduced ATP production correlated with nigral neuronal loss. Thyroid hormone levels were significantly increased in serum of PD rats compared to sham animals while steady expression of selected cytokines was detected in all groups. Hepatic enzyme functions were comparable in all animals. Our study indicates for the first time that in a rodent model of PD, hepatic mitochondria dysfunctions arise as a consequence of nigrostriatal degeneration, and that thyroid hormone represents a key interface in this CNS-liver interaction. Liver plays a fundamental detoxifying function and a better understanding of PD-related hepatic mitochondrial alterations, which might further promote neurodegeneration, may represent an important step for the development of novel therapeutic strategies.

Environmental exposure to manganese and motor function of children in Mexico

OBJECTIVES

Occupational manganese (Mn) exposure has been associated with motor deficits in adult workers, but data on the potential effects of environmental exposure to Mn on the developing motor function for a children population is scarce. The aim of this study was to evaluate the association between exposure to Mn and motor function of school aged children.

METHODS

We conducted a cross-sectional study selecting 195 children (100 exposed and 95 unexposed) between 7 and 11 years old. The following tests were used to evaluate the motor function: Grooved pegboard, finger tapping, and Santa Ana test. Mn exposure was assessed by blood (MnB) and hair concentrations (MnH). We constructed linear regression models to evaluate the association between exposure to Mn and the different test scores adjusting for age, sex, maternal education, hemoglobin and blood lead.

RESULTS

The median concentration of MnH and MnB was significantly higher in exposed (12.6 μg/g and 9.5 μg/L) compared to unexposed children (0.6 μg/g and 8.0 μg/L). The exposed children on average performed the grooved pegboard test faster, but made more errors, although these results did not reach statistical significance with neither one of the Mn exposure biomarkers. MnB showed an inverse association on the execution of the finger tapping test (average in 5 trials β -0.4, p=0.02), but no association was observed with MnH.

CONCLUSIONS

A subtle negative association of Mn exposure on motor speed and coordination was shown. In adults, the main effect of environmental Mn exposure has been associated with motor skills, but these results suggest that such alterations are not the main effect on children.

Age-associated variation in sensory perception of iron in drinking water and the potential for overexposure in the human population

Humans interact with their environment through the five senses, but little is known about population variability in the ability to assess contaminants. Sensory thresholds and biochemical indicators of metallic flavor perception in humans were evaluated for ferrous (Fe(2+)) iron in drinking water; subjects aged 19-84 years participated. Metallic flavor thresholds for individuals and subpopulations based on age were determined. Oral lipid oxidation and oral pH were measured in saliva as potential biochemical indicators. Individual thresholds were 0.007-14.14 mg/L Fe(2+) and the overall population threshold was 0.17 mg/L Fe(2+) in reagent water. Average thresholds for individuals younger and older than 50 years of age (grouped by the daily recommended nutritional guidelines for iron intake) were significantly different (p = 0.013); the population thresholds for each group were 0.045 mg/L Fe(2+) and 0.498 mg/L Fe(2+), respectively. Many subjects >50 and a few subjects <50 years were insensitive to metallic flavor. There was no correlation between age, oral lipid oxidation, and oral pH. Standardized olfactory assessment found poor sensitivity for Fe(2+) corresponded with conditions of mild, moderate, and total anosmia. The findings demonstrate an age-dependent sensitivity to iron indicating as people age they are less sensitive to metallic perception.