1
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de Souza Prestes A, Vargas JLS, Dos Santos MM, Druzian GT, da Rocha JT, Aschner M, Barbosa NV. EtHg is more toxic than MeHg to human peripheral blood mononuclear cells: Involvement of apoptotic, mitochondrial, oxidative and proliferative parameters. Biochim Biophys Acta Gen Subj 2023; 1867:130446. [PMID: 37619690 DOI: 10.1016/j.bbagen.2023.130446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 08/15/2023] [Accepted: 08/21/2023] [Indexed: 08/26/2023]
Abstract
BACKGROUND Methylmercury (MeHg) and ethylmercury (EtHg) are potent toxicants affecting the environment and human healthy. In this way, the present study aimed to investigate and compare the effects of MeHg and EtHg exposure on human peripheral blood mononuclear cells (PBMCs), which are critical components of the mammalian immune system. METHODS PBMCs were exposed to 2.5 μM MeHg or 2.5 μM EtHg. The number of cells and incubation times varied according to each assay. After exposures, the PBMCs were subjected to different evaluations, including cell viability, morphological aspects, cell cycle phases, indices of apoptosis and necrosis, reactive species (RS) production, and mitochondrial functionality. RESULTS PBMCs exposed to EtHg were characterized by decreased viability and size, increased granularity, RS production, and apoptotic indexes accompanied by an intensification of Sub-G1 and reduction in G0-G1 cell cycle phases. Preceding these effects, we found mitochondrial dysfunctions, namely a reduction in the electron transport system related to mitochondrial complex I. In contrast, PBMCs exposed to MeHg showed only reduced viability. By ICP-MS, we found that PBMCs treated with EtHg accumulated Hg + levels ∼1.8-fold greater than MeHg-exposed cells. CONCLUSIONS AND SIGNIFICANCE Taken together, our findings provide important insights about mercury immunotoxicity, showing that EtHg is more immunotoxic to human PBMCs than MeHg.
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Affiliation(s)
- Alessandro de Souza Prestes
- Department of Biochemistry and Molecular Biology, Federal University of Santa Maria, Santa Maria, RS, Brazil.
| | - João Luis Souza Vargas
- Department of Biochemistry and Molecular Biology, Federal University of Santa Maria, Santa Maria, RS, Brazil
| | - Matheus Mülling Dos Santos
- Department of Biochemistry and Molecular Biology, Federal University of Santa Maria, Santa Maria, RS, Brazil
| | | | - João Teixeira da Rocha
- Department of Biochemistry and Molecular Biology, Federal University of Santa Maria, Santa Maria, RS, Brazil
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Nilda Vargas Barbosa
- Department of Biochemistry and Molecular Biology, Federal University of Santa Maria, Santa Maria, RS, Brazil.
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2
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Puty B, Bittencourt LO, Plaça JR, de Oliveira EHC, Lima RR. Astrocyte-Like Cells Transcriptome Changes After Exposure to a Low and Non-cytotoxic MeHg Concentration. Biol Trace Elem Res 2023; 201:1151-1162. [PMID: 35378667 DOI: 10.1007/s12011-022-03225-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 03/29/2022] [Indexed: 02/07/2023]
Abstract
The central nervous system is the main target of MeHg toxicity and glial cells are the first line of defense; however, their true role remains unclear. This study aimed to identify the global map of human glial-like (U87) cells transcriptome after exposure to a non-toxic and non-lethal MeHg concentration and to investigate the related molecular changes. U87 cells were exposed upon 0.1, 0.5, and 1 µM MeHg for 4 and 24 h. Although no changes were observed in the percentage of viable cells, the metabolic viability was significantly decreased after exposure to 1 µM MeHg for 24 h; thus, the non-toxic concentration of 0.1 µM MeHg was chosen to perform microarray analysis. Significant changes in U87 cells transcriptome were observed only after 24 h. The expression of 392 genes was down regulated while 431 genes were up-regulated. Gene ontology showed alterations in biological processes (75%), cellular components (21%), and molecular functions (4%). The main pathways showed by KEGG and Reactome were cell cycle regulation and Rho GTPase signaling. The complex mechanism of U87 cells response against MeHg exposure indicates that even a low and non-toxic concentration is able to alter the gene expression profile.
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Affiliation(s)
- Bruna Puty
- Laboratory of Functional and Structural Biology, Institute of Biological Science, Federal University of Pará, Belém, Brazil
- Laboratory of Tissue Culture and Cytogenetics, Environmental Section, Evandro Chagas Institute, Ananindeua, Brazil
| | - Leonardo Oliveira Bittencourt
- Laboratory of Functional and Structural Biology, Institute of Biological Science, Federal University of Pará, Belém, Brazil
| | - Jéssica Rodrigues Plaça
- National Institute of Science and Technology in Stem Cell and Cell Therapy (INCT/CNPq) and Center for Cell-Based Therapy, CEPID/FAPESP, Ribeirão Preto, Brazil
| | | | - Rafael Rodrigues Lima
- Laboratory of Functional and Structural Biology, Institute of Biological Science, Federal University of Pará, Belém, Brazil.
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3
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Azevedo LF, Karpova N, Rocha BA, Barbosa Junior F, Gobe GC, Hornos Carneiro MF. Evidence on Neurotoxicity after Intrauterine and Childhood Exposure to Organomercurials. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:1070. [PMID: 36673825 PMCID: PMC9858833 DOI: 10.3390/ijerph20021070] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/03/2023] [Accepted: 01/04/2023] [Indexed: 06/17/2023]
Abstract
Although the molecular mechanisms underlying methylmercury toxicity are not entirely understood, the observed neurotoxicity in early-life is attributed to the covalent binding of methylmercury to sulfhydryl (thiol) groups of proteins and other molecules being able to affect protein post-translational modifications from numerous molecular pathways, such as glutamate signaling, heat-shock chaperones and the antioxidant glutaredoxin/glutathione system. However, for other organomercurials such as ethylmercury or thimerosal, there is not much information available. Therefore, this review critically discusses current knowledge about organomercurials neurotoxicity-both methylmercury and ethylmercury-following intrauterine and childhood exposure, as well as the prospects and future needs for research in this area. Contrasting with the amount of epidemiological evidence available for methylmercury, there are only a few in vivo studies reporting neurotoxic outcomes and mechanisms of toxicity for ethylmercury or thimerosal. There is also a lack of studies on mechanistic approaches to better investigate the pathways involved in the potential neurotoxicity caused by both organomercurials. More impactful follow-up studies, especially following intrauterine and childhood exposure to ethylmercury, are necessary. Childhood vaccination is critically important for controlling infectious diseases; however, the safety of mercury-containing thimerosal and, notably, its effectiveness as preservative in vaccines are still under debate regarding its potential dose-response effects to the central nervous system.
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Affiliation(s)
- Lara Ferreira Azevedo
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-903, SP, Brazil
| | - Nina Karpova
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-903, SP, Brazil
| | - Bruno Alves Rocha
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-903, SP, Brazil
| | - Fernando Barbosa Junior
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-903, SP, Brazil
| | - Glenda Carolyn Gobe
- Kidney Disease Research Group, School of Medicine, Translational Research Institute, University of Queensland, 37 Kent Street, Woolloongabba, QLD 4102, Australia
| | - Maria Fernanda Hornos Carneiro
- Department of Pharmacy, Faculty of Chemistry and Pharmacy, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
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4
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Neuron Protection by EDTA May Explain the Successful Outcomes of Toxic Metal Chelation Therapy in Neurodegenerative Diseases. Biomedicines 2022; 10:biomedicines10102476. [PMID: 36289738 PMCID: PMC9599085 DOI: 10.3390/biomedicines10102476] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/22/2022] [Accepted: 09/28/2022] [Indexed: 11/20/2022] Open
Abstract
Many mechanisms have been related to the etiopathogenesis of neurodegenerative diseases (NDs) such as multiple sclerosis, amyotrophic lateral sclerosis, Parkinson’s disease, and Alzheimer’s disease. In this context, the detrimental role of environmental agents has also been highlighted. Studies focused on the role of toxic metals in the pathogenesis of ND demonstrate the efficacy of treatment with the chelating agent calcium disodium ethylenediaminetetraacetic acid (EDTA) in eliminating toxic metal burden in all ND patients, improving their symptoms. Lead, cadmium, aluminum, nickel, and mercury were the most important toxic metals detected in these patients. Here, I provide an updated review on the damage to neurons promoted by toxic metals and on the impact of EDTA chelation therapy in ND patients, along with the clinical description of a representative case.
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5
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Kumar Rai R, Shankar Pati R, Islam A, Roy G. Detoxification of organomercurials by thiones and selones: A short review. Inorganica Chim Acta 2022. [DOI: 10.1016/j.ica.2022.120980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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6
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Sousa AH, Pereira JPG, Malaquias AC, Sagica FDES, de Oliveira EHC. Intracellular accumulation and DNA damage caused by methylmercury in glial cells. J Biochem Mol Toxicol 2022; 36:e23170. [PMID: 35822649 DOI: 10.1002/jbt.23170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 05/14/2022] [Accepted: 07/01/2022] [Indexed: 11/10/2022]
Abstract
Mercury is widely used in industrial and extractive processes, and the improper disposal of waste or products containing this metal produces a significant impact on ecosystems, causing adverse effects on living organisms, including humans. Exposure to methylmercury, a highly toxic organic compound, causes important neurological and developmental impairments. Recently, the genotoxicity of mercurial compounds has gained prominence as one of the possible mechanisms associated with the neurological effects of mercury, mostly by disturbing the mitotic spindle and causing chromosome loss. In this sense, it is important to investigate if these compounds can also cause direct damage to DNA, such as single and double-strand breaks. Thus, the aim of this study was to investigate the cytotoxic and genotoxic potential of methylmercury in cell lines derived from neurons (B103) and glia (C6), exposed to methylmercury (MeHg) for 24 h, by analyzing cell viability, metabolic activity, and damage to DNA and chromosomes. We found that in comparison to the neuronal cell line, glial cells showed higher tolerance to MeHg, and therefore a higher LC50 and consequent higher intracellular accumulation of Hg, which led to the occurrence of several genotoxic effects, as evidenced by the presence of micronuclei, bridges, sprouts, and chromosomal aberrations.
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Affiliation(s)
- Aline H Sousa
- Programa de Pós Graduação em Epidemiologia e vigilância em Saúde, Instituto Evandro Chagas, Ananindeua, Pará, Brazil.,Seção de Bacteriologia, Instituto Evandro Chagas, Ananindeua, Pará, Brazil
| | - João P G Pereira
- Programa de Pós Graduação em Epidemiologia e vigilância em Saúde, Instituto Evandro Chagas, Ananindeua, Pará, Brazil.,Seção de Meio Ambiente, Instituto Evandro Chagas, Ananindeua, Pará, Brazil
| | - Allan C Malaquias
- Faculdade de Medicina, Universidade Federal do Pará, Campus de Altamira, Pará, Brazil
| | | | - Edivaldo H C de Oliveira
- Seção de Meio Ambiente, Instituto Evandro Chagas, Ananindeua, Pará, Brazil.,Faculdade de Ciências Naturais, ICEN, Universidade Federal do Pará, Belém, Pará, Brazil
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7
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Hafey MJ, Aleksunes LM, Bridges CC, Brouwer KR, Chien HC, Leslie EM, Hu S, Li Y, Shen J, Sparreboom A, Sprowl J, Tweedie D, Lai Y. Transporters and Toxicity: Insights from the International Transporter Consortium Workshop 4. Clin Pharmacol Ther 2022; 112:527-539. [PMID: 35546260 DOI: 10.1002/cpt.2638] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 04/30/2022] [Indexed: 12/29/2022]
Abstract
Over the last decade, significant progress been made in elucidating the role of membrane transporters in altering drug disposition, with important toxicological consequences due to changes in localized concentrations of compounds. The topic of "Transporters and Toxicity" was recently highlighted as a scientific session at the International Transporter Consortium (ITC) Workshop 4 in 2021. The current white paper is not intended to be an extensive review on the topic of transporters and toxicity but an opportunity to highlight aspects of the role of transporters in various toxicities with clinically relevant implications as covered during the session. This includes a review of the role of solute carrier transporters in anticancer drug-induced organ injury, transporters as key players in organ barrier function, and the role of transporters in metal/metalloid toxicity.
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Affiliation(s)
- Michael J Hafey
- ADME and Discovery Toxicology, Merck & Co., Inc., Rahway, New Jersey, USA
| | - Lauren M Aleksunes
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, New Jersey, USA
| | - Christy C Bridges
- Department of Biomedical Sciences, Mercer University School of Medicine, Macon, Georgia, USA
| | | | - Huan-Chieh Chien
- Pharmacokinetics and Drug Metabolism, Amgen, Inc., South San Francisco, California, USA
| | - Elaine M Leslie
- Departments of Physiology and Lab Med and Path, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Shuiying Hu
- Division of Outcomes and Translational Sciences, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
| | - Yang Li
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
| | - Jinshan Shen
- Relay Therapeutics, Cambridge, Massachusetts, USA
| | - Alex Sparreboom
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
| | - Jason Sprowl
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, Buffalo, New York, USA
| | | | - Yurong Lai
- Drug Metabolism, Gilead Sciences Inc., Foster City, California, USA
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8
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Wildner G, Loreto JS, de Almeida P, Claro MT, Ferreira SA, Barbosa NV. Short exposure to ethyl and methylmercury prompts similar toxic responses in Drosophila melanogaster. Comp Biochem Physiol C Toxicol Pharmacol 2022; 252:109216. [PMID: 34710619 DOI: 10.1016/j.cbpc.2021.109216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/07/2021] [Accepted: 10/14/2021] [Indexed: 12/30/2022]
Abstract
Methylmercury (MeHg) and ethylmercury (EtHg) are important mercury organic forms in terms of human poisoning. Since the comparative effects of compounds are mainly in vitro, this study was designed to investigate the toxicities induced by MeHg and EtHg in an in vivo study using adult Drosophila melanogaster (D. melanogaster). Firstly, we performed a survival curve, where the flies were fed on a medium containing MeHg and EtHg at concentrations ranging from 2.5 to 200 μM, until the end of their lifespan. After that, the concentrations 25 and 200 μM of MeHg and EtHg were chosen to be tested in a short exposure for 5 days. The analysis of survival by Kaplan-Meier plot revealed that all concentrations of MeHg and EtHg reduced significantly the lifespan of the flies. Short exposure to both concentrations of MeHg and EtHg impaired the ability of flies in the climbing assay and induced lipid peroxidation. Only the flies exposed to the highest concentration had viability loss, thiol depletion, and increased reactive species (RS) and Hg levels in the whole body. Our findings indicate that MeHg and EtHg exhibit similar toxic effects in vivo, and that oxidative stress is a phenomenon behind the toxicity of both mercurials. The data obtained also reinforce the use of D. melanogaster as a useful organism for basic toxicological research.
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Affiliation(s)
- Guilherme Wildner
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Avenida Roraima, 1000, 97105-900 Santa Maria, RS, Brazil
| | - Julia Sepel Loreto
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Avenida Roraima, 1000, 97105-900 Santa Maria, RS, Brazil
| | - Pamela de Almeida
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Avenida Roraima, 1000, 97105-900 Santa Maria, RS, Brazil
| | - Mariana Torri Claro
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Avenida Roraima, 1000, 97105-900 Santa Maria, RS, Brazil
| | - Sabrina Antunes Ferreira
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Avenida Roraima, 1000, 97105-900 Santa Maria, RS, Brazil
| | - Nilda Vargas Barbosa
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Avenida Roraima, 1000, 97105-900 Santa Maria, RS, Brazil.
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9
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Erdemli-Köse SB, Yirün A, Balci-Özyurt A, Erkekoğlu P. Modification of the toxic effects of methylmercury and thimerosal by testosterone and estradiol in SH-SY5Y neuroblastoma cell line. J Appl Toxicol 2021; 42:981-994. [PMID: 34874569 DOI: 10.1002/jat.4269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/05/2021] [Accepted: 11/09/2021] [Indexed: 11/09/2022]
Abstract
Short-chained alkyl mercury compounds accumulate in particularly in the brain. Exposure to these compounds is associated with various neurotoxic effects. Gender-based differences are observed in neurodevelopmental disorders, and testosterone and estradiol may alter the toxic effect of the compounds. The present study aimed to investigate the toxic effects of methylmercury and thimerosal on SH-SY5Y cells in high testosterone/low estradiol and high estradiol/low testosterone containing cellular environment and estimate whether male and female brains react differently to the toxic effects of methylmercury and thimerosal. Study groups (n = 3) were designed as control: growth medium, thimerosal (T): 1.15-μM thimerosal, methylmercury (M): 2.93-μM methylmercury, high testosterone/low estradiol + thimerosal (TT): 1-μM testosterone + 0.75-μM estradiol + 1.15-μM thimerosal, high estradiol/low testosterone + thimerosal (ET): 0.1-μM testosterone + 7.5-μM estradiol + 1.15-μM thimerosal, high testosterone/low estradiol + methylmercury (TM): 1-μM testosterone + 0.75-μM estradiol + 2.93-μM methylmercury and high estradiol/low testosterone + methylmercury (EM): 0.1-μM testosterone + 7.5-μM estradiol + 2.93-μM methylmercury. While a significant decrease in glutathione levels was observed in M group, it was not seen in EM group. A significant increase in the protein carbonyl levels was detected in T group. A similar increase was observed in the TM and TT groups in which testosterone was dominant. It was determined that methylmercury, but not thimerosal, caused significant DNA damage and in TT group. The results showed that both thimerosal and methylmercury are toxic on SH-SY5Y cells and toxic effects of methylmercury are more severe than thimerosal. It has been determined that testosterone and estradiol alter the toxic effects of thimerosal and methylmercury.
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Affiliation(s)
- Selinay Başak Erdemli-Köse
- Department of Pharmaceutical Toxicology, Hacettepe University Faculty of Pharmacy, Ankara, Turkey.,Faculty of Arts and Sciences, Department of Chemistry, Burdur Mehmet Akif Ersoy University, Burdur, Turkey
| | - Anıl Yirün
- Department of Pharmaceutical Toxicology, Hacettepe University Faculty of Pharmacy, Ankara, Turkey.,Department of Pharmaceutical Toxicology, Çukurova University Faculty of Pharmacy, Adana, Turkey
| | - Aylin Balci-Özyurt
- Department of Pharmaceutical Toxicology, Hacettepe University Faculty of Pharmacy, Ankara, Turkey
| | - Pınar Erkekoğlu
- Department of Pharmaceutical Toxicology, Hacettepe University Faculty of Pharmacy, Ankara, Turkey.,Department of Vaccine Technology, Hacettepe University Vaccine Institute, Ankara, Turkey
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10
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Branco V, Aschner M, Carvalho C. Neurotoxicity of mercury: an old issue with contemporary significance. ADVANCES IN NEUROTOXICOLOGY 2021; 5:239-262. [PMID: 34263092 PMCID: PMC8276940 DOI: 10.1016/bs.ant.2021.01.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Mercury exerts a variety of toxic effects, depending on the specific compound and route of exposure. However, neurotoxicity in virtue of its consequence to health causes the greatest concern for toxicologists. This is particularly true regarding fetal development, where neurotoxic effects are much more severe than in adults, and the toxicity threshold is lower. Here, we review the major concepts regarding the neurotoxicity of mercury compounds (mercury vapor; methylmercury and ethylmercury), from exposure routes to toxicokinetic particularities leading to brain deposition and the development of neurotoxic effects. Albeit research on the neurotoxicity of mercury compounds has significantly advanced from the second half of the twentieth century onwards, several grey areas regarding the mechanism of toxicity still exist. Thus, we emphasize research advances during the last two decades concerning the molecular interactions of mercury which cause neurotoxic effects. Highlights include the disruption of glutamate signaling and excitotoxicity resulting from exposure to mercury and the interaction with redox active residues such as cysteines and selenocysteines which are the premise accounting for the disruption of redox homeostasis caused by mercurials. We also address how immunotoxic effects at the CNS, namely microglia and astrocyte activation modulate developmental neurotoxicity, a major topic in contemporary research.
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Affiliation(s)
- Vasco Branco
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, USA
| | - Cristina Carvalho
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
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11
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Geier DA, Kern JK, Homme KG, Geier MR. A Cross-Sectional Study of Blood Ethylmercury Levels and Cognitive Decline Among Older Adults and the Elderly in the United States. J Alzheimers Dis 2020; 72:901-910. [PMID: 31658062 PMCID: PMC6918911 DOI: 10.3233/jad-190894] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Cognitive health is an emerging public health concern for the aging American population. Mercury (Hg) is a toxic element that can cause nervous system damage. This hypothesis-testing study evaluated the relationship between blood ethyl-Hg levels and cognitive decline in an older adult and elderly American population. A total of 1,821,663 weighted-persons between 60-80 years old with detectable blood ethyl-Hg levels within the 2011-2012 National Health and Nutritional Examination Survey were examined. Those persons with blood ethyl-Hg levels greater than the median were deemed the higher ethyl-Hg exposure group and those with ethyl-Hg levels less than the median were deemed the lower ethyl-Hg exposure group. Three tests were utilized to measure cognitive function: 1) Consortium to Establish a Registry for Alzheimer's Disease - Word List Learning (CERAD W-L) delayed recall test, 2) animal fluency test, and 3) Digit Symbol Substitution Test. Each cognitive test score was categorized as higher for those with scores greater than the median and lower for those with scores less than the median. Survey logistic regression modeling with covariates was used to analyze the data for the relationship between blood ethyl-Hg levels and cognitive function scores. Significantly increased risks for lower animal fluency test (odds ratio (OR) = 13.652, p = 0.0029) and CERAD W-L delayed recall test (OR = 6.401, p = 0.0433) scores were observed among the higher ethyl-Hg exposure group as compared to the lower ethyl-Hg exposure group. This study supports the hypothesis that increased ethyl-Hg exposure is associated with significant cognitive decline in older adult and elderly Americans.
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Affiliation(s)
- David A Geier
- Institute of Chronic Illnesses, Inc., Silver Spring, MD, USA.,CoMeD, Inc., Silver Spring, MD, USA
| | - Janet K Kern
- Institute of Chronic Illnesses, Inc., Silver Spring, MD, USA.,CoMeD, Inc., Silver Spring, MD, USA.,CONEM US Autism Research Group, Allen, TX, USA
| | - Kristin G Homme
- International Academy of Oral Medicine and Toxicology, ChampionsGate, FL, USA
| | - Mark R Geier
- Institute of Chronic Illnesses, Inc., Silver Spring, MD, USA.,CoMeD, Inc., Silver Spring, MD, USA
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12
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Moser R, Zaccarini F, Alber T, Kerbl R. First finding of tiemannite, HgSe, in human bladder stones: An electron microprobe study. Micron 2020; 138:102928. [PMID: 32871494 DOI: 10.1016/j.micron.2020.102928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 08/18/2020] [Accepted: 08/18/2020] [Indexed: 11/24/2022]
Abstract
Human bladder stones, surgically removed from a 4 years old boy, were studied by X-ray diffraction (XRD) and by electron microprobe analyses (EPMA). XRD data show that the bladder stones are mainly composed of struvite with minor apatite. Tiny particles, <10 μm in size, composed of mercury (Hg) and selenium (Se) were found using scanning electron microscopy (SEM) and quantitative analysis by wave-length dispersive system (WDS). On the basis of their composition, the particles consist of tiemannite, a rare mineral with the ideal formula HgSe. The young patient was not exposed to relevant mercury contamination and has no teeth fillings of amalgam. Although this observation is not conclusive, we suggest that Hg was introduced as methylmercury by food. The discovered tiemannite can be classified as endogenous mineral, i.e., directly precipitated from the same fluids that formed the host bladder stones. This assumption is supported by the fact that tiemannite and struvite can crystallize at the same temperature and pH values. As proposed for the formation of tiemannite previously reported in the liver of cetaceans, we suggest that the tiemannite in the human body represents a probable product of demethylation of Hg. In this contribution, we suggest that Hg and Se were initially collected by urine in the human body and finally precipitated to form tiemannite under appropriate chemical-physical conditions together with the formation of the host bladder stone. This observation suggests that the precipitation and accumulation of metals, including Hg and Se, in the human body can be considered a physiological response to eliminate part of these trace elements, thus enabling detoxification.
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Affiliation(s)
- Reinhard Moser
- Leoben Hospital, Department of Pediatrics and Adolescent Medicine, A8700, Vordernberger Str. 42, Leoben, Austria.
| | - Federica Zaccarini
- University of Leoben, Department of Applied Geological Sciences and Geophysics, Peter Tunner Str. 5, A8700 Leoben, Austria.
| | - Thomas Alber
- Leoben Hospital, Department of Urology, Vordernberger Str. 42, A8700, Leoben, Austria.
| | - Reinhold Kerbl
- Leoben Hospital, Department of Pediatrics and Adolescent Medicine, A8700, Vordernberger Str. 42, Leoben, Austria.
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13
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Dórea JG. Neurotoxic effects of combined exposures to aluminum and mercury in early life (infancy). ENVIRONMENTAL RESEARCH 2020; 188:109734. [PMID: 32544722 DOI: 10.1016/j.envres.2020.109734] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/22/2020] [Accepted: 05/23/2020] [Indexed: 06/11/2023]
Abstract
Aluminum and mercury are environmentally ubiquitous. Individually they are both neurotoxic elements with shared neuro-pathogenic pathways: oxidative stress, altered neurotransmission, and disruption of the neuroendocrine and immune systems. In the infant, Al and Hg differ in type of exposure, absorption, distribution (brain access), and metabolism. In environmentally associated exposure (breast milk and infant formulas) their co-occurrences fluctuate randomly, but in Thimerosal-containing vaccines (TCVs) they occur combined in a proprietary ratio; in these cases, low-doses of Thimerosal-ethylmercury (EtHg) and adjuvant-Al present the most widespread binary mixture in less developed countries. Although experimental studies at low doses of the binary Hg and Al mixture are rare, when studied individually they have been shown to affect neurological outcomes negatively. In invitro systems, comparative neurotoxicity between Al and Hg varies in relation to the measured parameters but seems less for Al than for Hg. While neurotoxicity of environmental Hg (mainly fish methyl-Hg, MeHg) is associated with neurobehavioral outcomes in children, environmental Al is not associated, except in certain clinical conditions. Therefore, the issues of their neurotoxic effects (singly or combined) are discussed. In the infant (up to six months) the organic-Hg and Al body burdens from a full TCV schedule are estimated to reach levels higher than that originating from breastfeeding or from high aluminum soy-based formulas. Despite worldwide exposure to both Al and Hg (inorganic Hg, MeHg, and Thimerosal/EtHg), our knowledge on this combined exposure is insufficient to predict their combined neurotoxic effects (and with other co-occurring neurotoxicants).
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Affiliation(s)
- José G Dórea
- Universidade de Brasília, Brasília, 70919-970, DF, Brazil.
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14
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López-Berenguer G, Peñalver J, Martínez-López E. A critical review about neurotoxic effects in marine mammals of mercury and other trace elements. CHEMOSPHERE 2020; 246:125688. [PMID: 31896013 DOI: 10.1016/j.chemosphere.2019.125688] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/16/2019] [Accepted: 12/16/2019] [Indexed: 05/26/2023]
Abstract
Marine mammals are more exposed to mercury (Hg) than any others animals in the world. As many trace elements, Hg it is able to impair the brain function, which could be a cause of population decline. Nevertheless, these issues have been scarcely studied because of the technical and ethical difficulties. We conducted a systematic review about marine mammals' brain exposition to Hg and other trace elements, and their neurotoxic effects. Information was scarce and the lack of standardization of nomenclature of brain structures, sample collecting and results presentation made it difficult to obtain conclusions. Hg was the most studied metal and toothed whales the most studied group. Despite being its target organ, brain accumulates lesser concentrations of Hg than other tissues as liver. We found a significant positive correlation between both organs' burden (rho = 0.956 for cetaceans; rho = 0.756 for pinnipeds). Reported Hg values in brain of cetaceans (median 3.00 ppm ww) surpassed by one or two orders of magnitude those values found in other species as pinnipeds (median 0.33 ppm ww) or polar bears (median 0.07 ppm ww). Such values exceeded neurotoxicity thresholds. Although marine mammals ingest mostly the organic and more toxic form MeHg, different fractions of inorganic mercury can appear in brain, which could suggest some detoxification mechanisms. Other suggested mechanisms include Se-Hg interaction and liver sequestration. Although other elements are subjected to a rigid homeostatic control, appear in low concentrations or do not exert an important neurotoxic effect, they should be more studied to elucidate their neurotoxicity potential.
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Affiliation(s)
- G López-Berenguer
- Area of Toxicology, Department of Health Sciences, Faculty of Veterinary Medicine, University of Murcia, 30100, Murcia, Spain
| | - J Peñalver
- Area of Toxicology, Department of Health Sciences, Faculty of Veterinary Medicine, University of Murcia, 30100, Murcia, Spain; Fisheries and Aquaculture Service (CARM), 30100, Murcia, Spain
| | - E Martínez-López
- Area of Toxicology, Department of Health Sciences, Faculty of Veterinary Medicine, University of Murcia, 30100, Murcia, Spain; Toxicology and Risk Assessment Group, Biomedical Research Institute of Murcia (IMIB-Arrixaca), University of Murcia, 30100, Murcia, Spain.
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15
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Kern JK, Geier DA, Homme KG, Geier MR. Examining the evidence that ethylmercury crosses the blood-brain barrier. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2020; 74:103312. [PMID: 31841767 DOI: 10.1016/j.etap.2019.103312] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Revised: 12/06/2019] [Accepted: 12/06/2019] [Indexed: 06/10/2023]
Abstract
Scientific research can provide us with factual, repeatable, measurable, and determinable results. As such, scientific research can provide information that can be used in the decision-making process in the care of patients and in public policy. Although it has been suggested that ethylmercury (C2H5Hg+)-containing compounds do not cross the blood-brain barrier (BBB), this review examines the literature that addresses the question as to whether ethylmercury-containing compounds cross the BBB. The review will begin with cellular studies that provide evidence for the passive and active transport of mercury species across the BBB. Then, animal and clinical studies will be presented that specifically examine whether mercury accumulates in the brain after exposure to ethylmercury-containing compounds or Thimerosal (an ethylmercury-containing compound used as a preservative in vaccines and other drugs that metabolizes or degrades to ethylmercury-containing compounds and thiosalicylate). The results indicate that ethylmercury-containing compounds are actively transported across membranes by the L (leucine-preferring)-amino acid transport (LAT) system, the same as methylmercury-containing compounds. Further, 22 studies from 1971 to 2019 show that exposure to ethylmercury-containing compounds (intravenously, intraperitoneally, topically, subcutaneously, intramuscularly, or intranasally administered) results in accumulation of mercury in the brain. In total, these studies indicate that ethylmercury-containing compounds and Thimerosal readily cross the BBB, convert, for the most part, to highly toxic inorganic mercury-containing compounds, which significantly and persistently bind to tissues in the brain, even in the absence of concurrent detectable blood mercury levels.
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Affiliation(s)
- Janet K Kern
- Institute of Chronic Illnesses, Inc, Silver Spring, MD, USA; CoMeD, Inc, Silver Spring, MD, USA; CONEM US Autism Research Group, Allen, TX, USA.
| | - David A Geier
- Institute of Chronic Illnesses, Inc, Silver Spring, MD, USA; CoMeD, Inc, Silver Spring, MD, USA
| | - Kristin G Homme
- International Academy of Oral Medicine and Toxicology, ChampionsGate, FL, USA
| | - Mark R Geier
- Institute of Chronic Illnesses, Inc, Silver Spring, MD, USA; CoMeD, Inc, Silver Spring, MD, USA
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Ramos A, Dos Santos MM, de Macedo GT, Wildner G, Prestes AS, Masuda CA, Dalla Corte CL, Teixeira da Rocha JB, Barbosa NV. Methyl and Ethylmercury elicit oxidative stress and unbalance the antioxidant system in Saccharomyces cerevisiae. Chem Biol Interact 2020; 315:108867. [PMID: 31672467 DOI: 10.1016/j.cbi.2019.108867] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 10/07/2019] [Accepted: 10/21/2019] [Indexed: 11/19/2022]
Abstract
Methylmercury (MeHg) and Ethylmercury (EtHg) are toxic to the central nervous system. Human exposure to MeHg and EtHg results mainly from the consumption of contaminated fish and thimerosal-containing vaccines, respectively. The mechanisms underlying the toxicity of MeHg and EtHg are still elusive. Here, we compared the toxic effects of MeHg and EtHg in Saccharomyces cerevisiae (S. cerevisiae) emphasizing the involvement of oxidative stress and the identification of molecular targets from antioxidant pathways. Wild type and mutant strains with deleted genes for antioxidant defenses, namely: γ-glutamylcysteine synthetase, glutathione peroxidase, catalase, superoxide dismutase, mitochondrial peroxiredoxin, cytoplasmic thioredoxin, and redox transcription factor Yap1 were used to identify potential pathways and proteins from cell redox system targeted by MeHg and EtHg. MeHg and EtHg inhibited cell growth, decreased membrane integrity, and increased the granularity and production of reactive species (RS) in wild type yeast. The mutants were predominantly less tolerant of mercurial than wild type yeast. But, as the wild strain, mutants exhibited higher tolerance to MeHg than EtHg. Our results indicate the involvement of oxidative stress in the cytotoxicity of MeHg and EtHg and reinforce S. cerevisiae as a suitable model to explore the mechanisms of action of electrophilic toxicants.
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Affiliation(s)
- Angelica Ramos
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Matheus M Dos Santos
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Gabriel T de Macedo
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Guilherme Wildner
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Alessandro S Prestes
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Claudio A Masuda
- Instituto de Bioquímica Médica Leopoldo De Meis, Universidade Federal do Rio de Janeiro, RJ, Brazil
| | | | | | - Nilda V Barbosa
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
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Dórea JG. Multiple low-level exposures: Hg interactions with co-occurring neurotoxic substances in early life. Biochim Biophys Acta Gen Subj 2018; 1863:129243. [PMID: 30385391 DOI: 10.1016/j.bbagen.2018.10.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 10/01/2018] [Accepted: 10/19/2018] [Indexed: 12/11/2022]
Abstract
All chemical forms of Hg can affect neurodevelopment; however, low levels of organic Hg (methylmercury-MeHg and ethylmercury-EtHg in Thimerosal-containing vaccines, hereafter 'TCV') exposures during early life (pregnancy and lactation) co-occur with other environmental neurotoxic substances. These neurotoxicants may act in parallel, synergistically, or antagonistically to Hg. Nevertheless, the risks of neurotoxicity associated with multiple neuro-toxicants depend on type, time, combinations of exposure, and environmental and/or genetic-associated factors. Neurological developmental disorders, delays in cognition and behavioral outcomes associated with multiple exposures (which include Hg) may show transient or lasting outcomes depending on constitutional and/or environmental factors that can interact to neutralize, aggravate or attenuate these effects; often these studies are challenging to interpret. During pregnancy and lactation, fish-MeHg exposure is frequently confounded with the opposing effects of neuroactive nutrients (in fish) that lead to positive, negative, or no effects on neurobehavioral tests. In infancy, exposures to acute binary mixtures (TCV- EtHg and Al-adjuvants in infant immunizations) are associated with increased risks of tics and other developmental disorders. Despite the certitude that promulgates single environmental neurotoxicants, empirical comparisons of combined exposures indicate that Hg-related outcome is uneven. Hg in combination with other neurotoxic mixtures may elevate risks of neurotoxicity, but these risks arise in circumstances that are not yet predictable. Therefore, to achieve the goals of the Minamata treaty and to safeguard the health of children, low levels of mercury exposure (in any chemical form) needs to be further reduced whether the source is environmental (air- and food-borne) or iatrogenic (pediatric TCVs).
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Affiliation(s)
- José G Dórea
- Universidade de Brasília, Brasília 70919-970, DF, Brazil..
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18
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Dórea JG. Low-dose Thimerosal (ethyl-mercury) is still used in infants` vaccines: Should we be concerned with this form of exposure? J Trace Elem Med Biol 2018; 49:134-139. [PMID: 29895363 DOI: 10.1016/j.jtemb.2018.05.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Accepted: 05/16/2018] [Indexed: 12/25/2022]
Abstract
In developing countries, Thimerosal-containing vaccines (TCV) are the main causes of organic Hg exposure for newborns, neonates, and infants immunized with TCV. This article addresses early-life exposure to this unique organic mercury compound (ethylmercury-EtHg) and the risks of its exposure. English language studies pertaining to Thimerosal/EtHg toxicity and exposure during early life were searched in PubMed; and, those publications judged to be relevant to the topic of this review were selected. The risk from the neurotoxic effects of pre- and post-natal Hg exposures depend, in part, on aggravating or attenuating environmental and/or genetic-associated factors. Health authorities in charge of controlling infectious disease dismiss the toxicology of mercury (immunological and subtle neurological effects as insignificant) related to low-dose Thimerosal. The review addresses the evidence that brings into question the safety of Thimerosal that is still present in vaccines given to pregnant women, infants, and children in developing countries, and recognizes the ethical imperative to extend the use of Thimerosal-free vaccines to developing countries, not just developed countries.
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Affiliation(s)
- José G Dórea
- Health Sciences, Universidade de Brasília, Brasília, 70919-970, DF, Brazil.
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Patnaik R, Padhy RN. Comparative study on toxicity of methylmercury chloride and methylmercury hydroxide to the human neuroblastoma cell line SH-SY5Y. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:20606-20614. [PMID: 29752667 DOI: 10.1007/s11356-018-2164-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 04/26/2018] [Indexed: 05/27/2023]
Abstract
Toxicities of methylmercury chloride (CH3HgCl) and methylmercury hydroxide (CH3HgOH) to cultured neuroblastoma cell line SH-SY5Y in vitro are evaluated. This is the comparative study between two methylmercury compounds to find out the extent of toxicity of these compounds are toxic to SH-SY5Y cell line. Both cytotoxicity and genotoxicity experiments were carried out to find out the more toxic compound. For cytotoxicity study, four staining assay methods independently with trypan blue (TB), acridine orange/ethidium bromide (AO/EB), 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyl tetrazolium bromide (MTT), and neutral red (NR) were used and the comet assay method was done for genotoxicity study. The obtained toxicity data were used for probit analysis. In cytotoxicity, CH3HgCl had minimum inhibitory concentration (MIC) value in each assay method as 3 mg/L invariably; LC25 values were in the range 7.41 to 10.23 mg/L, and LC50 values were 14.79 to 15.48 mg/L; while LC75 values were 20.89 to 26.91 mg/L. Moreover, LC100 value was 30 mg/L, known from comet assay experiments for CH3HgCl. Similarly for CH3HgOH, the MIC value in each assay method was invariably 3 mg/L, the LC25 values were in the range 12.58 to 16.59 mg/L, and LC50 values were 19.49 to 23.44 mg/L; LC75 values were 27.54 to 30.90 mg/L and LC100 value was 42 mg/L in each assay done for cytotoxicity and genotoxicity studies. Computed DNA fragmentation indices in comet assays were 98.6 ± 0.57 30 mg/L with CH3HgCl and 76 ± 5.29 30 mg/L with CH3HgOH. This study clearly indicated that methylmercury chloride is more toxic than methylmercury hydroxide to SH-SY5Y cell line. Toxicity of Hg had been quantified with in vitro cultured human neuroblastoma cell line; since it has neurotoxic effects, its neural evaluation has implications in environmental health issues.
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Affiliation(s)
- Rajashree Patnaik
- Central Research Laboratory, IMS and Sum Hospital, Siksha 'O' Anusandhan University, Kalinga Nagar, Bhubaneswar, Odisha, 751003, India
| | - Rabindra N Padhy
- Central Research Laboratory, IMS and Sum Hospital, Siksha 'O' Anusandhan University, Kalinga Nagar, Bhubaneswar, Odisha, 751003, India.
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Garza-Lombó C, Posadas Y, Quintanar L, Gonsebatt ME, Franco R. Neurotoxicity Linked to Dysfunctional Metal Ion Homeostasis and Xenobiotic Metal Exposure: Redox Signaling and Oxidative Stress. Antioxid Redox Signal 2018; 28:1669-1703. [PMID: 29402131 PMCID: PMC5962337 DOI: 10.1089/ars.2017.7272] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
SIGNIFICANCE Essential metals such as copper, iron, manganese, and zinc play a role as cofactors in the activity of a wide range of processes involved in cellular homeostasis and survival, as well as during organ and tissue development. Throughout our life span, humans are also exposed to xenobiotic metals from natural and anthropogenic sources, including aluminum, arsenic, cadmium, lead, and mercury. It is well recognized that alterations in the homeostasis of essential metals and an increased environmental/occupational exposure to xenobiotic metals are linked to several neurological disorders, including neurodegeneration and neurodevelopmental alterations. Recent Advances: The redox activity of essential metals is key for neuronal homeostasis and brain function. Alterations in redox homeostasis and signaling are central to the pathological consequences of dysfunctional metal ion homeostasis and increased exposure to xenobiotic metals. Both redox-active and redox-inactive metals trigger oxidative stress and damage in the central nervous system, and the exact mechanisms involved are starting to become delineated. CRITICAL ISSUES In this review, we aim to appraise the role of essential metals in determining the redox balance in the brain and the mechanisms by which alterations in the homeostasis of essential metals and exposure to xenobiotic metals disturb the cellular redox balance and signaling. We focus on recent literature regarding their transport, metabolism, and mechanisms of toxicity in neural systems. FUTURE DIRECTIONS Delineating the specific mechanisms by which metals alter redox homeostasis is key to understand the pathological processes that convey chronic neuronal dysfunction in neurodegenerative and neurodevelopmental disorders. Antioxid. Redox Signal. 28, 1669-1703.
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Affiliation(s)
- Carla Garza-Lombó
- 1 Redox Biology Center and School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln , Lincoln, Nebraska.,2 Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas , Universidad Nacional Autónoma de México, Mexico City, México
| | - Yanahi Posadas
- 3 Departamentos de Farmacología y de, Centro de Investigación y de Estudios Avanzados (CINVESTAV) , Mexico City, México .,4 Departamentos de Química, Centro de Investigación y de Estudios Avanzados (CINVESTAV) , Mexico City, México
| | - Liliana Quintanar
- 4 Departamentos de Química, Centro de Investigación y de Estudios Avanzados (CINVESTAV) , Mexico City, México
| | - María E Gonsebatt
- 2 Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas , Universidad Nacional Autónoma de México, Mexico City, México
| | - Rodrigo Franco
- 1 Redox Biology Center and School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln , Lincoln, Nebraska
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The risk of neurodevelopmental disorders following Thimerosal-containing Hib vaccine in comparison to Thimerosal-free Hib vaccine administered from 1995 to 1999 in the United States. Int J Hyg Environ Health 2018; 221:677-683. [DOI: 10.1016/j.ijheh.2018.03.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Revised: 12/27/2017] [Accepted: 03/13/2018] [Indexed: 01/24/2023]
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Bjørklund G, Dadar M, Mutter J, Aaseth J. The toxicology of mercury: Current research and emerging trends. ENVIRONMENTAL RESEARCH 2017; 159:545-554. [PMID: 28889024 DOI: 10.1016/j.envres.2017.08.051] [Citation(s) in RCA: 240] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 08/27/2017] [Accepted: 08/30/2017] [Indexed: 05/16/2023]
Abstract
Mercury (Hg) is a persistent bio-accumulative toxic metal with unique physicochemical properties of public health concern since their natural and anthropogenic diffusions still induce high risk to human and environmental health. The goal of this review was to analyze scientific literature evaluating the role of global concerns over Hg exposure due to human exposure to ingestion of contaminated seafood (methyl-Hg) as well as elemental Hg levels of dental amalgam fillings (metallic Hg), vaccines (ethyl-Hg) and contaminated water and air (Hg chloride). Mercury has been recognized as a neurotoxicant as well as immunotoxic and designated by the World Health Organization as one of the ten most dangerous chemicals to public health. It has been shown that the half-life of inorganic Hg in human brains is several years to several decades. Mercury occurs in the environment under different chemical forms as elemental Hg (metallic), inorganic and organic Hg. Despite the raising understanding of the Hg toxicokinetics, there is still fully justified to further explore the emerging theories about its bioavailability and adverse effects in humans. In this review, we describe current research and emerging trends in Hg toxicity with the purpose of providing up-to-date information for a better understanding of the kinetics of this metal, presenting comprehensive knowledge on published data analyzing its metabolism, interaction with other metals, distribution, internal doses and targets, and reservoir organs.
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Affiliation(s)
- Geir Bjørklund
- Council for Nutritional and Environmental Medicine, Toften 24, 8610 Mo i Rana, Norway.
| | - Maryam Dadar
- Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
| | | | - Jan Aaseth
- Innlandet Hospital Trust and Inland Norway University of Applied Sciences, Elverum, Norway
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Methylmercury Uptake into BeWo Cells Depends on LAT2-4F2hc, a System L Amino Acid Transporter. Int J Mol Sci 2017; 18:ijms18081730. [PMID: 28786956 PMCID: PMC5578120 DOI: 10.3390/ijms18081730] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 07/28/2017] [Accepted: 08/01/2017] [Indexed: 12/24/2022] Open
Abstract
The organic mercury compound methylmercury (MeHg) is able to target the fetal brain. However, the uptake of the toxicant into placental cells is incompletely understood. MeHg strongly binds to thiol-S containing molecules such as cysteine. This MeHg-l-cysteine exhibits some structural similarity to methionine. System L plays a crucial role in placental transport of essential amino acids such as leucine and methionine and thus has been assumed to also transport MeHg-l-cysteine across the placenta. The uptake of methylmercury and tritiated leucine and methionine into the choriocarcinoma cell line BeWo was examined using transwell assay and small interfering (si)RNA mediated gene knockdown. Upon the downregulation of large neutral amino acids transporter (LAT)2 and 4F2 cell-surface antigen heavy chain (4F2hc), respectively, the levels of [3H]leucine in BeWo cells are significantly reduced compared to controls treated with non-targeting siRNA (p < 0.05). The uptake of [3H]methionine was reduced upon LAT2 down-regulation as well as methylmercury uptake after 4F2hc silencing (p < 0.05, respectively). These findings suggest an important role of system L in the placental uptake of the metal. Comparing the cellular accumulation of mercury, leucine, and methionine, it can be assumed that (1) MeHg is transported through system L amino acid transporters and (2) system L is responsible for the uptake of amino acids and MeHg primarily at the apical membrane of the trophoblast. The findings together can explain why mercury in contrast to other heavy metals such as lead or cadmium is efficiently transported to fetal blood.
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The Putative Role of Environmental Mercury in the Pathogenesis and Pathophysiology of Autism Spectrum Disorders and Subtypes. Mol Neurobiol 2017; 55:4834-4856. [DOI: 10.1007/s12035-017-0692-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Accepted: 07/13/2017] [Indexed: 01/28/2023]
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25
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Meinerz DF, Branco V, Aschner M, Carvalho C, Rocha JBT. Diphenyl diselenide protects against methylmercury-induced inhibition of thioredoxin reductase and glutathione peroxidase in human neuroblastoma cells: a comparison with ebselen. J Appl Toxicol 2017; 37:1073-1081. [DOI: 10.1002/jat.3458] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 01/30/2017] [Accepted: 01/31/2017] [Indexed: 12/14/2022]
Affiliation(s)
- Daiane F. Meinerz
- Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas; Universidade Federal de Santa Maria; 97105-900 Santa Maria RS Brazil
| | - Vasco Branco
- Research Institute for Medicines (iMed.ULisboa); Faculty of Pharmacy, Universidade de Lisboa; Av. Prof. Gama Pinto 1649-003 Lisbon Portugal
| | - Michael Aschner
- Department of Molecular Pharmacology; Albert Einstein College of Medicine; Forchheimer 209, 1300 Morris Park Avenue Bronx NY 10461 USA
| | - Cristina Carvalho
- Research Institute for Medicines (iMed.ULisboa); Faculty of Pharmacy, Universidade de Lisboa; Av. Prof. Gama Pinto 1649-003 Lisbon Portugal
| | - João Batista T. Rocha
- Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas; Universidade Federal de Santa Maria; 97105-900 Santa Maria RS Brazil
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Ghizoni H, de Souza V, Straliotto MR, de Bem AF, Farina M, Hort MA. Superoxide anion generation and oxidative stress in methylmercury-induced endothelial toxicity in vitro. Toxicol In Vitro 2017; 38:19-26. [DOI: 10.1016/j.tiv.2016.10.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 10/12/2016] [Accepted: 10/26/2016] [Indexed: 12/23/2022]
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27
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Dórea JG. Low-dose Thimerosal in pediatric vaccines: Adverse effects in perspective. ENVIRONMENTAL RESEARCH 2017; 152:280-293. [PMID: 27816865 DOI: 10.1016/j.envres.2016.10.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 10/26/2016] [Accepted: 10/27/2016] [Indexed: 06/06/2023]
Abstract
Vaccines are prophylactics used as the first line of intervention to prevent, control and eradicate infectious diseases. Young children (before the age of six months) are the demographic group most exposed to recommended/mandatory vaccines preserved with Thimerosal and its metabolite ethylmercury (EtHg). Particularly in the less-developed countries, newborns, neonates, and young children are exposed to EtHg because it is still in several of their pediatric vaccines and mothers are often immunized with Thimerosal-containing vaccines (TCVs) during pregnancy. While the immunogenic component of the product has undergone more rigorous testing, Thimerosal, known to have neurotoxic effects even at low doses, has not been scrutinized for the limit of tolerance alone or in combination with adjuvant-Al during immaturity or developmental periods (pregnant women, newborns, infants, and young children). Scientific evidence has shown the potential hazards of Thimerosal in experiments that modeled vaccine-EtHg concentrations. Observational population studies have revealed uncertainties related to neurological effects. However, consistently, they showed a link of EtHg with risk of certain neurodevelopment disorders, such as tic disorder, while clearly revealing the benefits of removing Thimerosal from children's vaccines (associated with immunological reactions) in developed countries. So far, only rich countries have benefited from withdrawing the risk of exposing young children to EtHg. Regarding Thimerosal administered to the very young, we have sufficient studies that characterize a state of uncertainty: the collective evidence strongly suggests that Thimerosal exposure is associated with adverse neurodevelopmental outcomes. It is claimed that the continued use of Thimerosal in the less-developed countries is due to the cost to change to another preservative, such as 2-phenoxyethanol. However, the estimated cost increase per child in the first year of life is lower than estimated lifetime cost of caring for a child with a neurodevelopmental disorder, such tic disorder. The evidence indicates that Thimerosal-free vaccine options should be made available in developing countries.
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Affiliation(s)
- José G Dórea
- Professor Emeritus, Faculty of Health Sciences, Universidade de Brasilia, 70919-970 Brasilia, DF, Brazil.
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Lohren H, Bornhorst J, Fitkau R, Pohl G, Galla HJ, Schwerdtle T. Effects on and transfer across the blood-brain barrier in vitro-Comparison of organic and inorganic mercury species. BMC Pharmacol Toxicol 2016; 17:63. [PMID: 27978854 PMCID: PMC5159962 DOI: 10.1186/s40360-016-0106-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 11/19/2016] [Indexed: 01/22/2023] Open
Abstract
Background Transport of methylmercury (MeHg) across the blood-brain barrier towards the brain side is well discussed in literature, while ethylmercury (EtHg) and inorganic mercury are not adequately characterized regarding their entry into the brain. Studies investigating a possible efflux out of the brain are not described to our knowledge. Methods This study compares, for the first time, effects of organic methylmercury chloride (MeHgCl), EtHg-containing thiomersal and inorganic Hg chloride (HgCl2) on as well as their transfer across a primary porcine in vitro model of the blood-brain barrier. Results With respect to the barrier integrity, the barrier model exhibited a much higher sensitivity towards HgCl2 following basolateral incubation (brain-facing side) as compared to apical application (blood-facing side). These HgCl2 induced effects on the barrier integrity after brain side incubation are comparable to that of the organic species, although MeHgCl and thiomersal exerted much higher cytotoxic effects in the barrier building cells. Hg transfer rates following exposure to organic species in both directions argue for diffusion as transfer mechanism. Inorganic Hg application surprisingly resulted in a Hg transfer out of the brain-facing compartment. Conclusions In case of MeHgCl and thiomersal incubation, mercury crossed the barrier in both directions, with a slight accumulation in the basolateral, brain-facing compartment, after simultaneous incubation in both compartments. For HgCl2, our data provide first evidence that the blood-brain barrier transfers mercury out of the brain.
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Affiliation(s)
- Hanna Lohren
- Department of Food Chemistry, Institute of Nutritional Science, Univeristy of Potsdam, Potsdam, Germany
| | - Julia Bornhorst
- Department of Food Chemistry, Institute of Nutritional Science, Univeristy of Potsdam, Potsdam, Germany
| | - Romy Fitkau
- Department of Food Chemistry, Institute of Nutritional Science, Univeristy of Potsdam, Potsdam, Germany
| | - Gabriele Pohl
- Department of Food Chemistry, Institute of Nutritional Science, Univeristy of Potsdam, Potsdam, Germany
| | | | - Tanja Schwerdtle
- Department of Food Chemistry, Institute of Nutritional Science, Univeristy of Potsdam, Potsdam, Germany.
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Yoshida S, Matsumoto S, Kanchika T, Hagiwara T, Minami T. The organic mercury compounds, methylmercury and ethylmercury, inhibited ciliary movement of ventricular ependymal cells in the mouse brain around the concentrations reported for human poisoning. Neurotoxicology 2016; 57:69-74. [DOI: 10.1016/j.neuro.2016.08.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 08/15/2016] [Indexed: 11/29/2022]
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Manceau A, Enescu M, Simionovici A, Lanson M, Gonzalez-Rey M, Rovezzi M, Tucoulou R, Glatzel P, Nagy KL, Bourdineaud JP. Chemical Forms of Mercury in Human Hair Reveal Sources of Exposure. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:10721-10729. [PMID: 27676331 DOI: 10.1021/acs.est.6b03468] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Humans are contaminated by mercury in different forms from different sources. In practice, contamination by methylmercury from fish consumption is assessed by measuring hair mercury concentration, whereas exposure to elemental and inorganic mercury from other sources is tested by analysis of blood or urine. Here, we show that diverse sources of hair mercury at concentrations as low as 0.5 ppm can be individually identified by specific coordination to C, N, and S ligands with high energy-resolution X-ray absorption spectroscopy. Methylmercury from seafood, ethylmercury used as a bactericide, inorganic mercury from dental amalgams, and exogenously derived atmospheric mercury bind in distinctive intermolecular configurations to hair proteins, as supported by molecular modeling. A mercury spike located by X-ray nanofluorescence on one hair strand could even be dated to removal of a single dental amalgam. Chemical forms of other known or putative toxic metals in human tissues could be identified by this approach with potential broader applications to forensic, energy, and materials science.
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Affiliation(s)
- Alain Manceau
- ISTerre, Université Grenoble Alpes, CNRS, CS 40700, 38058 Grenoble, France
| | - Mironel Enescu
- Laboratoire Chrono Environnement, Université de Franche-Comté, CNRS , 25030 Besançon, France
| | | | - Martine Lanson
- ISTerre, Université Grenoble Alpes, CNRS, CS 40700, 38058 Grenoble, France
| | | | - Mauro Rovezzi
- European Synchrotron Radiation Facility (ESRF), 71 Rue des Martyrs, 38000 Grenoble, France
| | - Rémi Tucoulou
- European Synchrotron Radiation Facility (ESRF), 71 Rue des Martyrs, 38000 Grenoble, France
| | - Pieter Glatzel
- European Synchrotron Radiation Facility (ESRF), 71 Rue des Martyrs, 38000 Grenoble, France
| | - Kathryn L Nagy
- Department of Earth and Environmental Sciences, MC-186, 845 West Taylor Street, University of Illinois at Chicago , Chicago, Illinois 60607, United States
| | - Jean-Paul Bourdineaud
- Institut Européen de Chimie et Biologie, Université de Bordeaux, CNRS , 2 rue Escarpit, 33607 Pessac, France
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Acosta G, Torres S, Kaplan M, Fernández LP, Pacheco PH, Gil RA. Liquid chromatography coupled to molecular fluorescence with postcolumn UV sensitization for thimerosal and derivative compounds monitoring in environmental samples. Electrophoresis 2016; 37:2531-2537. [DOI: 10.1002/elps.201600147] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 07/16/2016] [Accepted: 07/23/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Gimena Acosta
- Instituto de Química de San Luis; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, CCT-San Luis); San Luis Argentina
- Área de Gestión en Calidad y Salud, Facultad de Química Bioquímica y Farmacia; Universidad Nacional de San Luis; Chacabuco y Pedernera San Luis Argentina
| | - Sabier Torres
- Instituto de Química de San Luis; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, CCT-San Luis); San Luis Argentina
- Área de Química Analítica, Facultad de Química Bioquímica y Farmacia; Universidad Nacional de San Luis; Chacabuco y Pedernera San Luis Argentina
| | - Marcos Kaplan
- Instituto de Química de San Luis; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, CCT-San Luis); San Luis Argentina
- Área de Química Analítica, Facultad de Química Bioquímica y Farmacia; Universidad Nacional de San Luis; Chacabuco y Pedernera San Luis Argentina
| | - Liliana P. Fernández
- Instituto de Química de San Luis; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, CCT-San Luis); San Luis Argentina
- Área de Química Analítica, Facultad de Química Bioquímica y Farmacia; Universidad Nacional de San Luis; Chacabuco y Pedernera San Luis Argentina
| | - Pablo H. Pacheco
- Instituto de Química de San Luis; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, CCT-San Luis); San Luis Argentina
- Área de Farmacología y Toxicología, Facultad de Química Bioquímica y Farmacia; Universidad Nacional de San Luis; Chacabuco y Pedernera San Luis Argentina
| | - Raúl A. Gil
- Instituto de Química de San Luis; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, CCT-San Luis); San Luis Argentina
- Área de Química Analítica, Facultad de Química Bioquímica y Farmacia; Universidad Nacional de San Luis; Chacabuco y Pedernera San Luis Argentina
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Affiliation(s)
- Eva M. Krupp
- University of Aberdeen; Chemistry Department; Meston Walk Aberdeen AB24 3UE UK
| | - Zuzana Gajdosechova
- University of Aberdeen; Chemistry Department; Meston Walk Aberdeen AB24 3UE UK
| | - Tanja Schwerdtle
- University of Potsdam, Institute of Nutritional Science; Department of Food Chemistry; Arthur-Scheunert-Allee 114-116 14558 Nuthetal Germany
| | - Hanna Lohren
- University of Potsdam, Institute of Nutritional Science; Department of Food Chemistry; Arthur-Scheunert-Allee 114-116 14558 Nuthetal Germany
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Geier DA, Kern JK, Hooker BS, King PG, Sykes LK, Homme KG, Geier MR. Thimerosal exposure and increased risk for diagnosed tic disorder in the United States: a case-control study. Interdiscip Toxicol 2016; 8:68-76. [PMID: 27486363 PMCID: PMC4961900 DOI: 10.1515/intox-2015-0011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 04/10/2015] [Accepted: 04/23/2015] [Indexed: 01/08/2023] Open
Abstract
A hypothesis testing, case-control study evaluated automated medical records for exposure to organic-Hg from Thimerosal-containing hepatitis B vaccines (TM-HepB) administered at specific intervals in the first six-months-of-life among cases diagnosed with a tic disorder (TD) or cerebral degeneration (CD) (an outcome not biologically plausibly linked to TM exposure) in comparison to controls; both cases and controls were continuously enrolled from birth (born from 1991-2000) within the Vaccine Safety Datalink (VSD) database. TD cases were significantly more likely than controls to have received increased organic-Hg from TM-HepB administered within the first month-of-life (odds ratio (OR)=1.59, p<0.00001), first two-months-of-life (OR=1.59, p<0.00001), and first six-months-of-life (OR=2.97, p<0.00001). Male TD cases were significantly more likely than male controls to have received increased organic-Hg from TM-HepB administered within the first month-of-life (OR =1.65, p<0.0001), first two-months-of-life (OR=1.64, p<0.0001), and first six months-of-life (OR=2.47, p<0.05), where as female TD were significantly more likely than female controls to have received increased organic-Hg from TM-HepB administered within the first six-months-of-life (OR=4.97, p<0.05). By contrast, CD cases were no more likely than controls to have received increased organic-Hg exposure from TM-HepB administered at any period studied within the first six-months-of-life. Although routine childhood vaccination is considered an important public health tool to combat infectious diseases, the present study associates increasing organic-Hg exposure from TM-HepB and the subsequent risk of a TD diagnosis.
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Affiliation(s)
- David A Geier
- Institute of Chronic Illnesses, Inc., 14 Redgate Ct, Silver Spring, MD, USA
| | - Janet K Kern
- Institute of Chronic Illnesses, Inc., 14 Redgate Ct, Silver Spring, MD, USA
| | - Brian S Hooker
- Institute of Chronic Illnesses, Inc., 14 Redgate Ct, Silver Spring, MD, USA
| | - Paul G King
- Institute of Chronic Illnesses, Inc., 14 Redgate Ct, Silver Spring, MD, USA
| | - Lisa K Sykes
- Institute of Chronic Illnesses, Inc., 14 Redgate Ct, Silver Spring, MD, USA
| | - Kristin G Homme
- Institute of Chronic Illnesses, Inc., 14 Redgate Ct, Silver Spring, MD, USA
| | - Mark R Geier
- Institute of Chronic Illnesses, Inc., 14 Redgate Ct, Silver Spring, MD, USA
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Mechanisms involved in the transport of mercuric ions in target tissues. Arch Toxicol 2016; 91:63-81. [PMID: 27422290 DOI: 10.1007/s00204-016-1803-y] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 07/07/2016] [Indexed: 01/16/2023]
Abstract
Mercury exists in the environment in various forms, all of which pose a risk to human health. Despite guidelines regulating the industrial release of mercury into the environment, humans continue to be exposed regularly to various forms of this metal via inhalation or ingestion. Following exposure, mercuric ions are taken up by and accumulate in numerous organs, including brain, intestine, kidney, liver, and placenta. In order to understand the toxicological effects of exposure to mercury, a thorough understanding of the mechanisms that facilitate entry of mercuric ions into target cells must first be obtained. A number of mechanisms for the transport of mercuric ions into target cells and organs have been proposed in recent years. However, the ability of these mechanisms to transport mercuric ions and the regulatory features of these carriers have not been characterized completely. The purpose of this review is to summarize the current findings related to the mechanisms that may be involved in the transport of inorganic and organic forms of mercury in target tissues and organs. This review will describe mechanisms known to be involved in the transport of mercury and will also propose additional mechanisms that may potentially be involved in the transport of mercuric ions into target cells.
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Thimerosal-Preserved Hepatitis B Vaccine and Hyperkinetic Syndrome of Childhood. Brain Sci 2016; 6:brainsci6010009. [PMID: 26999226 PMCID: PMC4810179 DOI: 10.3390/brainsci6010009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2015] [Revised: 03/06/2016] [Accepted: 03/08/2016] [Indexed: 11/16/2022] Open
Abstract
(1) BACKGROUND: Hyperkinetic syndrome of childhood (HKSoC) is an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9) category in which the majority of the children are also diagnosed under the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision (DSM-IV-TR), where the umbrella term is "Attention-Deficit and Disruptive Behavior Disorders". The diagnostic criteria for HKSoC are developmentally inappropriate inattention, hyperactivity, and impulsivity. Some studies have implicated mercury (Hg) exposure as a risk factor. (2) METHODS: This hypothesis testing study; using the Vaccine Safety Datalink; assessed the toxicological effects of bolus exposure to organic-Hg from Thimerosal-containing vaccines (TCVs) by examining the relationship between Thimerosal-preserved hepatitis B vaccines (TM-HepB) given at varying levels and at specific intervals in the first six months after birth and the risk of a child being diagnosed with HKSoC. (3) RESULTS: Children diagnosed with HKSoC were significantly more likely to be exposed to increased organic-Hg from TM-HepB doses given within the first month (odds ratio = 1.45; 95% confidence interval (CI) = 1.30-1.62); within the first two months (odds ratio = 1.43; 95% CI = 1.28-1.59); and within the first six months (odds ratio = 4.51; 95% CI = 3.04-6.71) than controls. (4) CONCLUSION: The results indicate that increasing organic-Hg exposure from TCVs heightens the risk of a HKSoC diagnosis.
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Napolitano L, Scalise M, Galluccio M, Pochini L, Albanese LM, Indiveri C. LAT1 is the transport competent unit of the LAT1/CD98 heterodimeric amino acid transporter. Int J Biochem Cell Biol 2015; 67:25-33. [PMID: 26256001 DOI: 10.1016/j.biocel.2015.08.004] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 06/10/2015] [Accepted: 08/04/2015] [Indexed: 01/25/2023]
Abstract
LAT1 (SLC7A5) and CD98 (SLC3A2) constitute a heterodimeric transmembrane protein complex that catalyzes amino acid transport. Whether one or both subunits are competent for transport is still unclear. The present work aims to solve this question using different experimental strategies. Firstly, LAT1 and CD98 were immuno-detected in protein extracts from SiHa cells. Under oxidizing conditions, i.e., without addition of SH (thiol) reducing agent DTE, both proteins were revealed as a 120kDa major band. Upon DTE treatment separated bands, corresponding to LAT1(35kDa) or CD98(80kDa), were detected. LAT1 function was evaluated in intact cells as BCH sensitive [(3)H]His transport inhibited by hydrophobic amino acids. Antiport of [(3)H]His was measured in proteoliposomes reconstituted with SiHa cell extract in presence of internal His. Transport was increased by DTE. Hydrophobic amino acids were best inhibitors in addition to hydrophilic Tyr, Gln, Asn and Lys. Cys, Tyr and Gln, included in the intraliposomal space, were transported in antiport with external [(3)H]His. Similar experiments were performed in proteoliposomes reconstituted with the recombinant purified hLAT1. Results overlapping those obtained with native protein were achieved. Lower transport of [(3)H]Leu and [(3)H]Gln with respect to [(3)H]His was detected. Kinetic asymmetry was found with external Km for His lower than internal one. No transport was detected in proteoliposomes reconstituted with recombinant hCD98. The experimental data demonstrate that LAT1 is the sole transport competent subunit of the heterodimer. This conclusion has important outcome for following studies on functional characterization and identification of specific inhibitors with potential application in human therapy.
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Affiliation(s)
- Lara Napolitano
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Mariafrancesca Scalise
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Michele Galluccio
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Lorena Pochini
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Leticia Maria Albanese
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Cesare Indiveri
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy.
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Geier DA, Kern JK, Hooker BS, King PG, Sykes LK, Geier MR. A longitudinal cohort study of the relationship between Thimerosal-containing hepatitis B vaccination and specific delays in development in the United States: Assessment of attributable risk and lifetime care costs. J Epidemiol Glob Health 2015; 6:105-18. [PMID: 26166425 PMCID: PMC7320444 DOI: 10.1016/j.jegh.2015.06.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Revised: 05/04/2015] [Accepted: 06/01/2015] [Indexed: 12/15/2022] Open
Abstract
Epidemiological evidence suggests a link between mercury (Hg) exposure from Thimerosal-containing vaccines and specific delays in development. A hypothesis-testing longitudinal cohort study (n = 49,835) using medical records in the Vaccine Safety Datalink (VSD) was undertaken to evaluate the relationship between exposure to Hg from Thimerosal-containing hepatitis B vaccines (T-HBVs) administered at specific intervals in the first 6 months of life and specific delays in development [International Classification of Disease, 9th revision (ICD-9): 315.xx] among children born between 1991 and 1994 and continuously enrolled from birth for at least 5.81 years. Infants receiving increased Hg doses from T-HBVs administered within the first month, the first 2 months, and the first 6 months of life were significantly more likely to be diagnosed with specific delays in development than infants receiving no Hg doses from T-HBVs. During the decade in which T-HBVs were routinely recommended and administered to US infants (1991–2001), an estimated 0.5–1 million additional US children were diagnosed with specific delays in development as a consequence of 25 μg or 37.5 μg organic Hg from T-HBVs administered within the first 6 months of life. The resulting lifetime costs to the United States may exceed $1 trillion.
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Affiliation(s)
- David A Geier
- Institute of Chronic Illnesses, Inc, Silver Spring, MD, USA
| | - Janet K Kern
- Institute of Chronic Illnesses, Inc, Silver Spring, MD, USA.
| | - Brian S Hooker
- Biology Department, Simpson University, Redding, CA, USA
| | | | | | - Mark R Geier
- Institute of Chronic Illnesses, Inc, Silver Spring, MD, USA
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Tonazzi A, Giangregorio N, Console L, Scalise M, La Russa D, Notaristefano C, Brunelli E, Barca D, Indiveri C. Mitochondrial carnitine/acylcarnitine transporter, a novel target of mercury toxicity. Chem Res Toxicol 2015; 28:1015-22. [PMID: 25849418 DOI: 10.1021/acs.chemrestox.5b00050] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effect of Hg(2+) and CH3Hg(+) on the mitochondrial carnitine/acylcarnitine transporter (CACT) has been studied on the recombinant protein and on the CACT extracted from HeLa cells or Zebrafish and reconstituted in proteoliposomes. Transport was abolished upon treatment of the recombinant CACT in proteoliposomes by Hg(2+) or CH3Hg(+). Inhibition was reversed by the SH reducing agent 1,4-dithioerythritol, GSH, and N-acetylcysteine. IC50 for Hg(2+) and CH3Hg(+) of 90 nM and 137 nM, respectively, were measured by dose-response analyses. Inhibition was abolished in the C-less CACT mutant. Strong reduction of inhibition by both reagents was observed in the C136A and some reduction in the C155A mutants. Inhibition similar to that of the WT was observed in the C23V/C58V/C89S/C155V/C283S mutant, containing only C136. Optimal inhibition by Hg(2+)was found in the four replacement mutants C23V/C58V/C89S/C283S containing both C136 and C155 indicating cross-reaction of Hg(2+) with the two Cys residues. Inhibition kinetic analysis showed mixed inhibition by Hg(2+) or competitive inhibition by CH3Hg(+). HeLa cells or Zebrafish were treated with the more potent inhibitor. Ten micromolar HgCl2 caused clear impairment of viability of HeLa cells. The transport assay in proteoliposomes with CACT extracted from treated cells showed that the transporter was inactivated and that DTE rescued the activity. Nearly identical results were observed with Zebrafish upon extraction of the CACT from the liver of the treated animals that, indeed, showed accumulation of the mercurial compound.
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Affiliation(s)
- Annamaria Tonazzi
- †CNR Institute of Biomembranes and Bioenergetics, via Amendola 165/A, 70126 Bari, Italy.,‡Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy
| | - Nicola Giangregorio
- †CNR Institute of Biomembranes and Bioenergetics, via Amendola 165/A, 70126 Bari, Italy.,‡Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy
| | - Lara Console
- §Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Mariafrancesca Scalise
- §Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Daniele La Russa
- §Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Caterina Notaristefano
- ‡Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy
| | - Elvira Brunelli
- §Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Donatella Barca
- §Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Cesare Indiveri
- †CNR Institute of Biomembranes and Bioenergetics, via Amendola 165/A, 70126 Bari, Italy.,§Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
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Geier DA, King PG, Hooker BS, Dórea JG, Kern JK, Sykes LK, Geier MR. Thimerosal: Clinical, epidemiologic and biochemical studies. Clin Chim Acta 2015; 444:212-20. [DOI: 10.1016/j.cca.2015.02.030] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 02/06/2015] [Accepted: 02/14/2015] [Indexed: 10/24/2022]
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Acosta G, Spisso A, Fernández LP, Martinez LD, Pacheco PH, Gil RA. Determination of thimerosal in pharmaceutical industry effluents and river waters by HPLC coupled to atomic fluorescence spectrometry through post-column UV-assisted vapor generation. J Pharm Biomed Anal 2015; 106:79-84. [DOI: 10.1016/j.jpba.2014.09.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 09/08/2014] [Accepted: 09/09/2014] [Indexed: 01/14/2023]
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Geier DA, Kern JK, King PG, Sykes LK, Geier MR. A case-control study evaluating the relationship between thimerosal-containing haemophilus influenzae type b vaccine administration and the risk for a pervasive developmental disorder diagnosis in the United States. Biol Trace Elem Res 2015; 163:28-38. [PMID: 25382662 PMCID: PMC4297306 DOI: 10.1007/s12011-014-0169-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 10/30/2014] [Indexed: 10/26/2022]
Abstract
Thimerosal is an organic mercury (Hg)-containing compound (49.55 % Hg by weight) historically added to many multi-dose vials of vaccine as a preservative. A hypothesis testing case-control study evaluated automated medical records in the Vaccine Safety Datalink (VSD) for organic Hg exposure from Thimerosal in Haemophilus influenzae type b (Hib)-containing vaccines administered at specific times within the first 15 months of life among subjects diagnosed with pervasive developmental disorder (PDD) (n = 534) in comparison to controls. The generally accepted biologically non-plausible linkage between Thimerosal exposure and subsequent diagnosis of febrile seizure (n = 5886) was examined as a control outcome. Cases diagnosed with PDD received significantly more organic Hg within the first 6 months of life (odds ratio (OR) = 1.97, p < 0.001) and first 15 months of life (OR = 3.94, p < 0.0001) than controls, whereas cases diagnosed with febrile seizure were no more likely than controls to have received increased organic Hg. On a per microgram of organic Hg basis, cases diagnosed with a PDD in comparison to controls were at significantly greater odds (OR = 1.0197, p < 0.0001) of receiving increasing organic Hg exposure within the first 15 months of life, whereas cases diagnosed febrile seizure were no more likely than controls (OR = 0.999, p > 0.20) to have received increasing organic Hg exposure within the first 15 months of life. Routine childhood vaccination is an important public health tool to reduce the morbidity and mortality associated with infectious diseases, but the present study provides new epidemiological evidence of a significant relationship between increasing organic Hg exposure from Thimerosal-containing vaccines and the subsequent risk of PDD diagnosis in males and females.
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Affiliation(s)
- David A. Geier
- The Institute of Chronic Illnesses, Inc, 14 Redgate Ct, Silver Spring, MD 20905 USA
| | - Janet K. Kern
- The Institute of Chronic Illnesses, Inc, 14 Redgate Ct, Silver Spring, MD 20905 USA
- Department of Psychiatry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX USA
| | | | | | - Mark R. Geier
- The Institute of Chronic Illnesses, Inc, 14 Redgate Ct, Silver Spring, MD 20905 USA
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Lohren H, Bornhorst J, Galla HJ, Schwerdtle T. The blood–cerebrospinal fluid barrier – first evidence for an active transport of organic mercury compounds out of the brain. Metallomics 2015; 7:1420-30. [DOI: 10.1039/c5mt00171d] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hg strongly transfers across the blood–CSF barrier towards the blood side after incubation with organic Hg compounds.
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Affiliation(s)
- Hanna Lohren
- Department of Food Chemistry
- Institute of Nutritional Science
- University of Potsdam
- 14558 Nuthetal, Germany
| | - Julia Bornhorst
- Department of Food Chemistry
- Institute of Nutritional Science
- University of Potsdam
- 14558 Nuthetal, Germany
| | | | - Tanja Schwerdtle
- Department of Food Chemistry
- Institute of Nutritional Science
- University of Potsdam
- 14558 Nuthetal, Germany
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Geier DA, Kern JK, Hooker BS, King PG, Sykes LK, Geier MR. Thimerosal-containing hepatitis B vaccination and the risk for diagnosed specific delays in development in the United States: a case-control study in the vaccine safety datalink. NORTH AMERICAN JOURNAL OF MEDICAL SCIENCES 2014; 6:519-31. [PMID: 25489565 PMCID: PMC4215490 DOI: 10.4103/1947-2714.143284] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Background: Within the first 3 years of life, the brain develops rapidly. Its development is characterized by critical developmental periods for speech, vision, hearing, language, balance, etc.; and alteration in any of the processes occurring in those critical periods can lead to specific delays in development. Aims: The present study evaluated the potential toxic effects of organic-mercury exposure from Thimerosal (49.55% mercury by weight) in childhood vaccines and its hypothesized possible relationship with specific delays in development. Materials and Methods: A hypothesis testing case-control study was undertaken to evaluate the relationship between exposure to Thimerosal-containing hepatitis B vaccines administered at specific intervals in the first 6 months among cases diagnosed with specific delays in development and controls born between 1991-2000, utilizing data in the Vaccine Safety Datalink database. Results: Cases were significantly more likely than controls to have received increased organic-mercury from Thimerosal-containing hepatitis B vaccine administered in the first, second, and sixth month of life. Conclusion: Though routine childhood vaccination may be an important public health tool to reduce the morbidity and mortality associated with infectious diseases, the present study supports an association between increasing organic-mercury exposure from Thimerosal-containing childhood vaccines and the subsequent risk of specific delays in development among males and females.
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Affiliation(s)
- David A Geier
- Institute of Chronic Illnesses, Inc, Silver Spring, Maryland, USA
| | - Janet K Kern
- Institute of Chronic Illnesses, Inc, Silver Spring, Maryland, USA ; Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Brian S Hooker
- Biology Department, Simpson University, Redding, California, USA
| | | | | | - Mark R Geier
- Institute of Chronic Illnesses, Inc, Silver Spring, Maryland, USA
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Carneiro MFH, Oliveira Souza JM, Grotto D, Batista BL, de Oliveira Souza VC, Barbosa F. A systematic study of the disposition and metabolism of mercury species in mice after exposure to low levels of thimerosal (ethylmercury). ENVIRONMENTAL RESEARCH 2014; 134:218-227. [PMID: 25173055 DOI: 10.1016/j.envres.2014.07.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Revised: 07/15/2014] [Accepted: 07/17/2014] [Indexed: 06/03/2023]
Abstract
Thimerosal (TM) is an ethylmercury (etHg)-containing preservative used in some vaccines despite very limited knowledge on the kinetics and direct interaction/effects in mammals׳ tissues after exposure. Thus, this study aimed to evaluate the kinetics of Hg species in mice in a time course analysis after intramuscular injection of TM, by estimating Hg half-lives in blood and tissues. Mice were exposed to one single intramuscular dose of 20 µg of Hg as TM. Blood, brain, heart, kidney and liver were collected at 0.5 hour (h), 1 h, 8 h, 16 h, 144 h, 720 h and 1980 h after TM exposure (n=4). Hg species in animal tissues were identified and quantified by speciation analysis via liquid chromatography hyphenated with inductively coupled mass spectrometry (LC-ICP-MS). It was found that the transport of etHg from muscle to tissues and its conversion to inorganic Hg (inoHg) occur rapidly. Moreover, the conversion extent is modulated in part by the partitioning between EtHg in plasma and in whole blood, since etHg is rapidly converted in red cells but not in a plasma compartment. Furthermore, the dealkylation mechanism in red cells appears to be mediated by the Fenton reaction (hydroxyl radical formation). Interestingly, after 0.5 h of TM exposure, the highest levels of both etHg and inoHg were found in kidneys (accounting for more than 70% of the total Hg in the animal body), whereas the brain contributed least to the Hg body burden (accounts for <1.0% of total body Hg). Thirty days after TM exposure, most Hg had been excreted while the liver presented the majority of the remaining Hg. Estimated half-lives (in days) were 8.8 for blood, 10.7 for brain, 7.8 for heart, 7.7 for liver and 45.2 for kidney. Taken together, our findings demonstrated that TM (etHg) kinetics more closely approximates Hg(2+) than methylmercury (meHg) while the kidney must be considered a potential target for etHg toxicity.
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Affiliation(s)
- Maria Fernanda Hornos Carneiro
- Laboratório de Toxicologia e Essencialidade de Metais, Faculdade de Ciências Farmacêuticas de Ribeirão Preto - USP, Avenida do Café, s/n, Monte Alegre, CEP 14040-903 Ribeirão Preto, SP, Brazil.
| | - Juliana Maria Oliveira Souza
- Laboratório de Toxicologia e Essencialidade de Metais, Faculdade de Ciências Farmacêuticas de Ribeirão Preto - USP, Avenida do Café, s/n, Monte Alegre, CEP 14040-903 Ribeirão Preto, SP, Brazil.
| | - Denise Grotto
- Laboratório de Toxicologia e Essencialidade de Metais, Faculdade de Ciências Farmacêuticas de Ribeirão Preto - USP, Avenida do Café, s/n, Monte Alegre, CEP 14040-903 Ribeirão Preto, SP, Brazil; Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade de Sorocaba, Rodovia Raposo Tavares km 92.5, CEP 18023-000 Sorocaba, SP, Brazil.
| | - Bruno Lemos Batista
- Laboratório de Toxicologia e Essencialidade de Metais, Faculdade de Ciências Farmacêuticas de Ribeirão Preto - USP, Avenida do Café, s/n, Monte Alegre, CEP 14040-903 Ribeirão Preto, SP, Brazil; Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Bloco B, Avenida dos Estados 5001, CEP 0910-170 Santo André, SP, Brazil.
| | - Vanessa Cristina de Oliveira Souza
- Laboratório de Toxicologia e Essencialidade de Metais, Faculdade de Ciências Farmacêuticas de Ribeirão Preto - USP, Avenida do Café, s/n, Monte Alegre, CEP 14040-903 Ribeirão Preto, SP, Brazil.
| | - Fernando Barbosa
- Laboratório de Toxicologia e Essencialidade de Metais, Faculdade de Ciências Farmacêuticas de Ribeirão Preto - USP, Avenida do Café, s/n, Monte Alegre, CEP 14040-903 Ribeirão Preto, SP, Brazil.
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A dose-response relationship between organic mercury exposure from thimerosal-containing vaccines and neurodevelopmental disorders. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2014; 11:9156-70. [PMID: 25198681 PMCID: PMC4199012 DOI: 10.3390/ijerph110909156] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Revised: 08/07/2014] [Accepted: 08/26/2014] [Indexed: 11/25/2022]
Abstract
A hypothesis testing case-control study evaluated concerns about the toxic effects of organic-mercury (Hg) exposure from thimerosal-containing (49.55% Hg by weight) vaccines on the risk of neurodevelopmental disorders (NDs). Automated medical records were examined to identify cases and controls enrolled from their date-of-birth (1991–2000) in the Vaccine Safety Datalink (VSD) project. ND cases were diagnosed with pervasive developmental disorder (PDD), specific developmental delay, tic disorder or hyperkinetic syndrome of childhood. In addition, putative non-thimerosal-related outcomes of febrile seizure, failure to thrive and cerebral degenerations were examined. The cumulative total dose of Hg exposure from thimerosal-containing hepatitis B vaccine (T-HBV) administered within the first six months of life was calculated. On a per microgram of organic-Hg basis, PDD (odds ratio (OR) = 1.054), specific developmental delay (OR = 1.035), tic disorder (OR = 1.034) and hyperkinetic syndrome of childhood (OR = 1.05) cases were significantly more likely than controls to receive increased organic-Hg exposure. By contrast, none of the non-thimerosal related outcomes were significantly more likely than the controls to have received increased organic-Hg exposure. Routine childhood vaccination may be an important public health tool to reduce infectious disease-associated morbidity/mortality, but the present study significantly associates organic-Hg exposure from T-HBV with an increased risk of an ND diagnosis.
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Zimmermann LT, dos Santos DB, Colle D, dos Santos AA, Hort MA, Garcia SC, Bressan LP, Bohrer D, Farina M. Methionine stimulates motor impairment and cerebellar mercury deposition in methylmercury-exposed mice. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2014; 77:46-56. [PMID: 24555646 DOI: 10.1080/15287394.2014.865582] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Methylmercury (MeHg) is a highly toxic environmental contaminant that produces neurological and developmental impairments in animals and humans. Although its neurotoxic properties have been widely reported, the molecular mechanisms by which MeHg enters the cells and exerts toxicity are not yet completely understood. Taking into account that MeHg is found mostly bound to sulfhydryl-containing molecules such as cysteine in the environment and based on the fact that the MeHg-cysteine complex (MeHg-S-Cys) can be transported via the L-type neutral amino acid carrier transport (LAT) system, the potential beneficial effects of L-methionine (L-Met, a well known LAT substrate) against MeHg (administrated as MeHg-S-Cys)-induced neurotoxicity in mice were investigated. Mice were exposed to MeHg (daily subcutaneous injections of MeHg-S-Cys, 10 mg Hg/kg) and/or L-Met (daily intraperitoneal injections, 250 mg/kg) for 10 consecutive days. After treatments, the measured hallmarks of toxicity were mostly based on behavioral parameters related to motor performance, as well as biochemical parameters related to the cerebellar antioxidant glutathione (GSH) system. MeHg significantly decreased motor activity (open-field test) and impaired motor performance (rota-rod task) compared with controls, as well as producing disturbances in the cerebellar antioxidant GSH system. Interestingly, L-Met administration did not protect against MeHg-induced behavioral and cerebellar changes, but rather increased motor impairments in animals exposed to MeHg. In agreement with this observation, cerebellar levels of mercury (Hg) were higher in animals exposed to MeHg plus L-Met compared to those only exposed to MeHg. However, this event was not observed in kidney and liver. These results are the first to demonstrate that L-Met enhances cerebellar deposition of Hg in mice exposed to MeHg and that this higher deposition may be responsible for the greater motor impairment observed in mice simultaneously exposed to MeHg and L-Met.
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Affiliation(s)
- Luciana T Zimmermann
- a Departamento de Bioquímica, Centro de Ciências Biológicas , Universidade Federal de Santa Catarina , Florianópolis , Santa Catarina , Brazil
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Geier DA, Hooker BS, Kern JK, King PG, Sykes LK, Geier MR. A two-phase study evaluating the relationship between Thimerosal-containing vaccine administration and the risk for an autism spectrum disorder diagnosis in the United States. Transl Neurodegener 2013; 2:25. [PMID: 24354891 PMCID: PMC3878266 DOI: 10.1186/2047-9158-2-25] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2013] [Accepted: 12/16/2013] [Indexed: 11/20/2022] Open
Abstract
Background Autism spectrum disorder (ASD) is defined by standardized criteria of qualitative impairments in social interaction, qualitative impairments in communication, and restricted and stereotyped patterns of behavior, interests, and activities. A significant number of children diagnosed with ASD suffer a loss of previously-acquired skills, which is suggestive of neurodegeneration or a type of progressive encephalopathy with an etiological pathogenic basis occurring after birth. To date, the etiology of ASD remains under debate, however, many studies suggest toxicity, especially from mercury (Hg), in individuals diagnosed with an ASD. The present study evaluated concerns about the toxic effects of organic-Hg exposure from Thimerosal (49.55% Hg by weight) in childhood vaccines by conducting a two-phased (hypothesis generating/hypothesis testing) study with documented exposure to varying levels of Thimerosal from vaccinations. Methods A hypothesis generating cohort study was undertaken to evaluate the relationship between exposure to organic-Hg from a Thimerosal-containing Diphtheria-Tetanus-acellular-Pertussis (DTaP) vaccine in comparison to a Thimerosal-free DTaP vaccine administered, from 1998 through 2000, for the risk of ASD as reported in the Vaccine Adverse Event Reporting System (VAERS) database (phase I). A hypothesis testing case–control study was undertaken to evaluate the relationship between organic-Hg exposure from Thimerosal-containing hepatitis B vaccines administered at specific intervals in the first six months of life among cases diagnosed with an ASD and controls born between 1991 through 1999 in the Vaccine Safety Datalink (VSD) database (phase II). Results In phase I, it was observed that there was a significantly increased risk ratio for the incidence of ASD reported following the Thimerosal-containing DTaP vaccine in comparison to the Thimerosal-free DTaP vaccine. In phase II, it was observed that cases diagnosed with an ASD were significantly more likely than controls to receive increased organic-Hg from Thimerosal-containing hepatitis B vaccine administered within the first, second, and sixth month of life. Conclusions Routine childhood vaccination is an important public health tool to reduce the morbidity and mortality associated with infectious diseases, but the present study provides new epidemiological evidence supporting an association between increasing organic-Hg exposure from Thimerosal-containing childhood vaccines and the subsequent risk of an ASD diagnosis.
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Affiliation(s)
| | | | | | | | | | - Mark R Geier
- The Institute of Chronic Illnesses Inc, 14 Redgate Ct, Silver Spring, MD, USA.
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Kern JK, Haley BE, Geier DA, Sykes LK, King PG, Geier MR. Thimerosal exposure and the role of sulfation chemistry and thiol availability in autism. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2013; 10:3771-800. [PMID: 23965928 PMCID: PMC3774468 DOI: 10.3390/ijerph10083771] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 07/10/2013] [Accepted: 07/11/2013] [Indexed: 01/22/2023]
Abstract
Autism spectrum disorder (ASD) is a neurological disorder in which a significant number of the children experience a developmental regression characterized by a loss of previously acquired skills and abilities. Typically reported are losses of verbal, nonverbal, and social abilities. Several recent studies suggest that children diagnosed with an ASD have abnormal sulfation chemistry, limited thiol availability, and decreased glutathione (GSH) reserve capacity, resulting in a compromised oxidation/reduction (redox) and detoxification capacity. Research indicates that the availability of thiols, particularly GSH, can influence the effects of thimerosal (TM) and other mercury (Hg) compounds. TM is an organomercurial compound (49.55% Hg by weight) that has been, and continues to be, used as a preservative in many childhood vaccines, particularly in developing countries. Thiol-modulating mechanisms affecting the cytotoxicity of TM have been identified. Importantly, the emergence of ASD symptoms post-6 months of age temporally follows the administration of many childhood vaccines. The purpose of the present critical review is provide mechanistic insight regarding how limited thiol availability, abnormal sulfation chemistry, and decreased GSH reserve capacity in children with an ASD could make them more susceptible to the toxic effects of TM routinely administered as part of mandated childhood immunization schedules.
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Affiliation(s)
- Janet K. Kern
- Institute of Chronic Illnesses, Inc., Silver Spring, MD 20905, USA; E-Mails: (D.A.G.); (M.R.G.)
| | - Boyd E. Haley
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA; E-Mail:
| | - David A. Geier
- Institute of Chronic Illnesses, Inc., Silver Spring, MD 20905, USA; E-Mails: (D.A.G.); (M.R.G.)
| | - Lisa K. Sykes
- CoMeD, Inc., Silver Spring, MD 20905, USA; E-Mails: (L.K.S.); (P.G.K.)
| | - Paul G. King
- CoMeD, Inc., Silver Spring, MD 20905, USA; E-Mails: (L.K.S.); (P.G.K.)
| | - Mark R. Geier
- Institute of Chronic Illnesses, Inc., Silver Spring, MD 20905, USA; E-Mails: (D.A.G.); (M.R.G.)
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