1001
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Budtz-Jørgensen E, Grandjean P, Weihe P. Separation of risks and benefits of seafood intake. ENVIRONMENTAL HEALTH PERSPECTIVES 2007; 115:323-7. [PMID: 17431478 PMCID: PMC1849938 DOI: 10.1289/ehp.9738] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Accepted: 12/14/2006] [Indexed: 05/14/2023]
Abstract
BACKGROUND Fish and seafood provide important nutrients but may also contain toxic contaminants, such as methylmercury. Advisories against pollutants may therefore conflict with dietary recommendations. In resolving this conundrum, most epidemiologic studies provide little guidance because they address either nutrient benefits or mercury toxicity, not both. OBJECTIVES Impact on the same health outcomes by two exposures originating from the same food source provides a classical example of confounding. To explore the extent of this bias, we applied structural equation modeling to data from a prospective study of developmental methylmercury neurotoxicity in the Faroe Islands. RESULTS Adjustment for the benefits conferred by maternal fish intake during pregnancy resulted in an increased effect of the prenatal methylmercury exposure, as compared with the unadjusted results. The dietary questionnaire response is likely to be an imprecise proxy for the transfer of seafood nutrients to the fetus, and this imprecision may bias the confounder-adjusted mercury effect estimate. We explored the magnitude of this bias in sensitivity analysis assuming a range of error variances. At realistic imprecision levels, mercury-associated deficits increased by up to 2-fold when compared with the unadjusted effects. CONCLUSIONS These results suggest that uncontrolled confounding from a beneficial parameter, and imprecision of this confounder, may cause substantial underestimation of the effects of a toxic exposure. The adverse effects of methylmercury exposure from fish and seafood are therefore likely to be underestimated by unadjusted results from observational studies, and the extent of this bias will be study dependent.
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Affiliation(s)
- Esben Budtz-Jørgensen
- Department of Biostatistics, Institute of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Philippe Grandjean
- Institute of Public Health, University of Southern Denmark, Odense, Denmark
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA
- Address correspondence to P. Grandjean, Institute of Public Health, University of Southern Denmark, Winslowparken 17, 5000 Odense, Denmark. Telephone: 45-6550.3769. Fax: 45-6591.1458. E-mail:
| | - Pal Weihe
- Institute of Public Health, University of Southern Denmark, Odense, Denmark
- Faroese Hospital System, Tórshavn, Faroe Islands
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1002
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dos Santos APM, Mateus ML, Carvalho CML, Batoréu MCC. Biomarkers of exposure and effect as indicators of the interference of selenomethionine on methylmercury toxicity. Toxicol Lett 2007; 169:121-8. [PMID: 17267146 DOI: 10.1016/j.toxlet.2006.12.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Accepted: 12/19/2006] [Indexed: 10/23/2022]
Abstract
The present study was conducted to clarify the interference of selenomethionine (SeMet) on methylmercury (MeHg) toxicity through the evaluation of changes in biomarkers of exposure and effect in rats exposed to MeHg and co-exposed to MeHg and SeMet. Male Wistar rats received two intraperitoneally (i.p.) administrations, either MeHg (1.5mg/kg body weight), SeMet alone (1mg/kg body weight) or combined MeHg and SeMet, followed by 3 weeks of rat urine collection and neurobehavioural assays. The effects of different administrations were investigated by the quantification of total mercury in kidney and brain, analysis of urinary porphyrins, determination of hepatic GSH and evaluation of motor activity functions (rearing and ambulation). MeHg exposure resulted in a significant increase of urinary porphyrins during the 3 weeks of rat urine collection, where as it caused a significant decrease in motor activity only at the first day after cessation of rat exposure. Additionally, SeMet co-exposure was able to normalize the porphyrins excretion, and a tendency to restore rat motor activity was observed, on the first day after cessation of exposure. Brain and kidney mercury levels increased significantly in rats exposed to MeHg; however, in co-exposed rats to SeMet no significant changes in Hg levels were found as compared to rats exposed to MeHg alone. Hence, the present study shows that urinary porphyrins are sensitive and persistent indicators of MeHg toxicity and demonstrates for the first time that SeMet reduces its formation. Finally, these results confirm that the mechanism of interaction between SeMet and MeHg cannot be explained by the reduction of Hg levels in target organs and suggestions are made to clarify the interference of SeMet on MeHg toxicity.
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Affiliation(s)
- Ana P M dos Santos
- Centro de Estudos de Ciências Farmacêuticas, Faculty of Pharmacy, University of Lisbon, Av. Prof. Gama Pinto, 1649-003 Lisbon, Portugal
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1003
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Brodkin E, Copes R, Mattman A, Kennedy J, Kling R, Yassi A. Lead and mercury exposures: interpretation and action. CMAJ 2007; 176:59-63. [PMID: 17200393 PMCID: PMC1764574 DOI: 10.1503/cmaj.060790] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Lead and mercury are naturally occurring elements in the earth's crust and are common environmental contaminants. Because people concerned about possible exposures to these elements often seek advice from their physicians, clinicians need to be aware of the signs and symptoms of lead and mercury poisoning, how to investigate a possible exposure and when intervention is necessary. We describe 3 cases of patients who presented to an occupational medicine specialist with concerns of heavy metal toxicity. We use these cases to illustrate some of the issues surrounding the investigation of possible lead and mercury exposures. We review the common sources of exposure, the signs and symptoms of lead and mercury poisoning and the appropriate use of chelation therapy. There is a need for a clear and consistent guide to help clinicians interpret laboratory investigations. We offer such a guide, with information about population norms, lead and mercury levels that suggest exposure beyond that seen in the general population and levels that warrant referral for advice about clinical management.
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Affiliation(s)
- Elizabeth Brodkin
- Community Medicine Residency Program, Department of Medicine, Faculty of Medicine, University of British Columbia.
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1004
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Mergler D, Anderson HA, Chan LHM, Mahaffey KR, Murray M, Sakamoto M, Stern AH. Methylmercury exposure and health effects in humans: a worldwide concern. AMBIO 2007; 36:3-11. [PMID: 17408186 DOI: 10.1579/0044-7447(2007)36[3:meahei]2.0.co;2] [Citation(s) in RCA: 669] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The paper builds on existing literature, highlighting current understanding and identifying unresolved issues about MeHg exposure, health effects, and risk assessment, and concludes with a consensus statement. Methylmercury is a potent toxin, bioaccumulated and concentrated through the aquatic food chain, placing at risk people, throughout the globe and across the socioeconomic spectrum, who consume predatory fish or for whom fish is a dietary mainstay. Methylmercury developmental neurotoxicity has constituted the basis for risk assessments and public health policies. Despite gaps in our knowledge on new bioindicators of exposure, factors that influence MeHg uptake and toxicity, toxicokinetics, neurologic and cardiovascular effects in adult populations, and the nutritional benefits and risks from the large number of marine and freshwater fish and fish-eating species, the panel concluded that to preserve human health, all efforts need to be made to reduce and eliminate sources of exposure.
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Affiliation(s)
- Donna Mergler
- Department of Biological Sciences, Institute for Environmental Sciences, University of Québec, Montreal, Canada.
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1005
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Sutton DJ, Tchounwou PB. Mercury-induced externalization of phosphatidylserine and caspase 3 activation in human liver carcinoma (HepG2) cells. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2007; 3:38-42. [PMID: 16823075 PMCID: PMC3785678 DOI: 10.3390/ijerph2006030005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Apoptosis arises from the active initiation and propagation of a series of highly orchestrated specific biochemical events leading to the demise of the cell. It is a normal physiological process, which occurs during embryonic development as well as in the maintenance of tissue homeostasis. Diverse groups of molecules are involved in the apoptosis pathway and it functions as a mechanism to eliminate unwanted or irreparably damaged cells. However, inappropriate induction of apoptosis by environmental agents has broad ranging pathologic implications and has been associated with several diseases including cancer. The toxicity of several heavy metals such as mercury has been attributed to their high affinity to sulfhydryl groups of proteins and enzymes, and their ability to disrupt cell cycle progression and/or apoptosis in various tissues. The aim of this study was to assess the potential for mercury to induce early and late-stage apoptosis in human liver carcinoma (HepG2) cells. The Annexin-V and Caspase 3 assays were performed by flow cytometric analysis to determine the extent of phosphatidylserine externalization and Caspase 3 activation in mercury-treated HepG2 cells. Cells were exposed to mercury for 10 and 48 hours respectively at doses of 0, 1, 2, and 3 microg/mL based on previous cytotoxicity results in our laboratory indicating an LD50 of 3.5 +/- 0.6 microg/mL for mercury in HepG2 cells. The study data indicated a dose response relationship between mercury exposure and the degree of early and late-stage apoptosis in HepG2 cells. The percentages of cells undergoing early apoptosis were 0.03 +/- 0.03%, 5.19 +/- 0.04%, 6.36 +/- 0.04%, and 8.84 +/- 0.02% for 0, 1, 2, and 3 microg/mL of mercury respectively, indicating a gradual increase in apoptotic cells with increasing doses of mercury. The percentages of Caspase 3 positive cells undergoing late apoptosis were 3.58 +/- 0.03%, 17.06 +/- 0.05%, 23.32 +/- 0.03%, and 34.51 +/- 0.01% for 0, 1, 2, and 3 microg/mL of mercury respectively, also indicating a gradual increase in Caspase positive cells with increasing doses of mercury.
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Affiliation(s)
- Dwayne J. Sutton
- Molecular Toxicology Research laboratory, NIH-Center for Environmental Health, College of Science, Engineering and Technology, Jackson State University, 1400 Lynch Street, Box 18540 Jackson, Mississippi 39217,
USA
| | - Paul B. Tchounwou
- Molecular Toxicology Research laboratory, NIH-Center for Environmental Health, College of Science, Engineering and Technology, Jackson State University, 1400 Lynch Street, Box 18540 Jackson, Mississippi 39217,
USA
- Correspondence to Dr. Paul B. Tchounwou.
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1006
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Abstract
This review covers the toxicology of mercury and its compounds. Special attention is paid to those forms of mercury of current public health concern. Human exposure to the vapor of metallic mercury dates back to antiquity but continues today in occupational settings and from dental amalgam. Health risks from methylmercury in edible tissues of fish have been the subject of several large epidemiological investigations and continue to be the subject of intense debate. Ethylmercury in the form of a preservative, thimerosal, added to certain vaccines, is the most recent form of mercury that has become a public health concern. The review leads to general discussion of evolutionary aspects of mercury, protective and toxic mechanisms, and ends on a note that mercury is still an "element of mystery."
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Affiliation(s)
- Thomas W Clarkson
- Department of Environmental Medicine, University of Rochester School of Medicine, New York, USA.
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1007
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Abstract
The safety of mercury-containing dental amalgam has been hotly debated for well over a century. Dental exposures from mercury have been suggested as the cause of numerous diseases including multiple sclerosis, autism and many others. Known health effects of mercury exposure include CNS and renal damage. However, these effects have only been shown at occupational or higher levels of exposure, and have not been conclusively shown to be present at levels of mercury exposure consistent with that from dental amalgam fillings. The use of mercury amalgam fillings remains a state-of-the-art treatment for dental caries throughout the world. Although there have been a small number of peer-reviewed reports examining the health effects of dental mercury in children, only very recently have the only randomised, controlled clinical trials (two) of the safety of mercury amalgam been published. The purpose of this review is to discuss the scientific evidence on the safety of the use of mercury-containing dental amalgam as a treatment for dental caries.
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Affiliation(s)
- Michael D Martin
- Associate Professor of Oral Medicine, University of Washington, School of Dentistry, Department of Oral Medicine, Box 356370, Seattle, WA 98195, USA.
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1008
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Fok TF, Lam HS, Ng PC, Yip ASK, Sin NC, Chan IHS, Gu GJS, So HK, Wong EMC, Lam CWK. Fetal methylmercury exposure as measured by cord blood mercury concentrations in a mother-infant cohort in Hong Kong. ENVIRONMENT INTERNATIONAL 2007; 33:84-92. [PMID: 16962662 DOI: 10.1016/j.envint.2006.08.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2006] [Revised: 07/26/2006] [Accepted: 08/04/2006] [Indexed: 05/11/2023]
Abstract
This study was designed to examine newborn infants in Hong Kong prenatally exposed to levels of methylmercury considered to increase risk of neurotoxic effects and to examine subject characteristics that modify the degree of prenatal mercury exposure. Mercury concentrations in 1057 sets of maternal and cord blood samples and 96 randomly selected maternal hair samples were measured. Subject characteristics were measured or collected by questionnaire. Of the 1057 cord blood samples collected only 21.6% had mercury concentrations less than 29 nmol/L (5.8 micro g/L). Median maternal hair mercury concentration was 1.7 ppm. The geometric mean cord to maternal blood mercury ratio was 1.79 to 1. Increasing maternal fish consumption and maternal age were found to be associated with increased cord blood mercury concentrations. Marine fish consumption increased cord blood mercury concentrations more than freshwater fish (5.09%/kg vs 2.86%/kg). Female babies, maternal alcohol consumption and increasing maternal height were associated with decreased cord blood mercury concentrations. Pregnant women in Hong Kong consume large amounts of fish and as a result, most of their offspring have been prenatally exposed to moderately high levels of mercury. In this population, pregnant women should choose freshwater over marine fish and limit fish consumption.
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Affiliation(s)
- Tai F Fok
- Department of Paediatrics, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong.
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1009
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Nikolic J, Stojanovic I, Pavlovic R, Sokolovic D, Bjelakovic G, Beninati S. The role of L-arginine in toxic liver failure: interrelation of arginase, polyamine catabolic enzymes and nitric oxide synthase. Amino Acids 2007; 32:127-31. [PMID: 16699819 DOI: 10.1007/s00726-006-0309-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2005] [Accepted: 03/02/2006] [Indexed: 12/12/2022]
Abstract
The existing interrelation in metabolic pathways of L-arginine to polyamines, nitric oxide (NO) and urea synthesis could be affected in sepsis, inflammation, intoxication and other conditions. The role of polyamines and NO in the toxic effect of mercury chloride on rat liver function was studied. Administration of mercury chloride for 24 h led to significantly elevated plasma activities of Alanine transaminase (ALT) and Aspartate transaminase (AST). Malondyaldehyde (MDA) levels were unaffected (p > 0.05) and arginase activity was significantly decreased (p < 0.05) while nitrate/nitrite production was significantly elevated (p < 0.001) in liver tissue. Polyamine oxidase (PAO) and diamine oxidase (DAO) activities, enzymes involved in catabolism of polyamines, were decreased. L-arginine supplementation to intoxicated rats potentiated the effect of mercury chloride on NO production and it was ineffective on arginase activity. Results obtained in this study show that mercury chloride-induced toxicity leads to abnormally high levels of ALT and AST that may indicate liver damage with the involvement of polyamine catabolic enzymes and NO.
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Affiliation(s)
- J Nikolic
- Department of Biochemistry, School of Medicine, University of Nis, Nis, Serbia and Montenegro.
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1010
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Grim CE, Grim CM. Office Blood Pressure Measurement. Hypertension 2007. [DOI: 10.1016/b978-1-4160-3053-9.50011-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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1011
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Yin Z, Milatovic D, Aschner JL, Syversen T, Rocha JB, Souza DO, Sidoryk M, Albrecht J, Aschner M. Methylmercury induces oxidative injury, alterations in permeability and glutamine transport in cultured astrocytes. Brain Res 2006; 1131:1-10. [PMID: 17182013 PMCID: PMC1847599 DOI: 10.1016/j.brainres.2006.10.070] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2006] [Revised: 10/09/2006] [Accepted: 10/26/2006] [Indexed: 01/12/2023]
Abstract
The neurotoxicity of high levels of methylmercury (MeHg) is well established both in humans and experimental animals. Astrocytes accumulate MeHg and play a prominent role in mediating MeHg toxicity in the central nervous system (CNS). Although the precise mechanisms of MeHg neurotoxicity are ill-defined, oxidative stress and altered mitochondrial and cell membrane permeability appear to be critical factors in its pathogenesis. The present study examined the effects of MeHg treatment on oxidative injury, mitochondrial inner membrane potential, glutamine uptake and expression of glutamine transporters in primary astrocyte cultures. MeHg caused a significant increase in F(2)-isoprostanes (F(2)-IsoPs), lipid peroxidation biomarkers of oxidative damage, in astrocyte cultures treated with 5 or 10 microM MeHg for 1 or 6 h. Consistent with this observation, MeHg induced a concentration-dependant reduction in the inner mitochondrial membrane potential (DeltaPsi(m)), as assessed by the potentiometric dye, tetramethylrhodamine ethyl ester (TMRE). Our results demonstrate that DeltaPsi(m) is a very sensitive endpoint for MeHg toxicity, since significant reductions were observed after only 1 h exposure to concentrations of MeHg as low as 1 microM. MeHg pretreatment (1, 5 and 10 microM) for 30 min also inhibited the net uptake of glutamine ((3)H-glutamine) measured at 1 min and 5 min. Expression of the mRNA coding the glutamine transporters, SNAT3/SN1 and ASCT2, was inhibited only at the highest (10 microM) MeHg concentration, suggesting that the reduction in glutamine uptake observed after 30 min treatment with lower concentrations of MeHg (1 and 5 microM) was not due to inhibition of transcription. Taken together, these studies demonstrate that MeHg exposure is associated with increased mitochondrial membrane permeability, alterations in glutamine/glutamate cycling, increased ROS formation and consequent oxidative injury. Ultimately, MeHg initiates multiple additive or synergistic disruptive mechanisms that lead to cellular dysfunction and cell death.
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MESH Headings
- Amino Acid Transport Systems, Neutral/genetics
- Animals
- Animals, Newborn
- Astrocytes/drug effects
- Astrocytes/metabolism
- Astrocytes/pathology
- Cell Membrane Permeability/drug effects
- Cell Membrane Permeability/physiology
- Cells, Cultured
- Central Nervous System/drug effects
- Central Nervous System/metabolism
- Central Nervous System/physiopathology
- Dose-Response Relationship, Drug
- Glutamic Acid/metabolism
- Glutamine/metabolism
- Lipid Peroxidation/drug effects
- Lipid Peroxidation/physiology
- Membrane Potential, Mitochondrial/drug effects
- Membrane Potential, Mitochondrial/physiology
- Mercury Poisoning, Nervous System/metabolism
- Mercury Poisoning, Nervous System/physiopathology
- Methylmercury Compounds/toxicity
- Mitochondria/drug effects
- Mitochondria/metabolism
- Mitochondria/pathology
- Mitochondrial Membranes/drug effects
- Mitochondrial Membranes/metabolism
- Mitochondrial Membranes/pathology
- Oxidative Stress/drug effects
- Oxidative Stress/physiology
- RNA, Messenger/drug effects
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Reactive Oxygen Species/metabolism
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Affiliation(s)
- Zhaobao Yin
- Department of Pediatrics, Pharmacology, and the Kennedy Center, Norwegian University of Science and Technology, Trondheim, Norway
| | - Dejan Milatovic
- Department of Pediatrics, Pharmacology, and the Kennedy Center, Norwegian University of Science and Technology, Trondheim, Norway
| | - Judy L. Aschner
- Department of Pediatrics, Pharmacology, and the Kennedy Center, Norwegian University of Science and Technology, Trondheim, Norway
| | - Tore Syversen
- Department of Clinical Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway
| | - Joao B.T. Rocha
- Departamento de Análises Clínicas e Toxicológicas, Centro de Ciências da Saúde, Universidade Federal de Santa Maria, Brazil
| | - Diogo O. Souza
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Marta Sidoryk
- Department of Neurotoxicology, Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Jan Albrecht
- Department of Neurotoxicology, Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Michael Aschner
- Department of Pediatrics, Pharmacology, and the Kennedy Center, Norwegian University of Science and Technology, Trondheim, Norway
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1012
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The safety of amalgam compared with resin composite restorations in children older than 8 years showed no significant differences on neurobehavioral or nerve conduction studies during a 7-year follow-up. J Evid Based Dent Pract 2006; 6:280-2. [PMID: 17174253 DOI: 10.1016/j.jebdp.2006.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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1013
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Franco JL, Braga HDC, Nunes AKC, Ribas CM, Stringari J, Silva AP, Garcia Pomblum SC, Moro AM, Bohrer D, Santos ARS, Dafre AL, Farina M. Lactational exposure to inorganic mercury: evidence of neurotoxic effects. Neurotoxicol Teratol 2006; 29:360-7. [PMID: 17222531 DOI: 10.1016/j.ntt.2006.11.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Revised: 11/23/2006] [Accepted: 11/24/2006] [Indexed: 11/27/2022]
Abstract
This study examined the effects of inorganic mercury (mercuric chloride - HgCl2) exposure exclusively through maternal milk on biochemical parameters related to oxidative stress (glutathione and thiobarbituric acid reactive substances levels, glutathione peroxidase and glutathione reductase activities) in the cerebellum of weanling mice. These parameters were also evaluated in the cerebellum of mothers, which were subjected to intraperitoneal injections of HgCl2 (0, 0.5 and 1.5 mg/kg, once a day) during the lactational period. Considering the relationship between cerebellar function and motor activity, the presence of motor impairment was also evaluated in the offspring exposed to HgCl2 during lactation. After treatments (at weaning), pups lactationally exposed to inorganic mercury showed high levels of mercury in the cerebellar tissue, as well as significant impairment in motor performance in the rotarod task and decreased locomotor activity in the open field. Offspring and dams did not show changes in cerebellar glutathione levels or glutathione peroxidase activity. In pups, lactational exposure to inorganic mercury significantly increased cerebellar lipoperoxidation, as well as the activity of cerebellar glutathione reductase. However, these phenomena were not observed in dams. These results indicate that inorganic mercury exposure through maternal milk is capable of inducing biochemical changes in the cerebellum of weanling mice, as well as motor deficit and these phenomena appear to be related to the pro-oxidative properties of inorganic mercury.
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Affiliation(s)
- Jeferson L Franco
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil
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1014
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Chen YW, Huang CF, Tsai KS, Yang RS, Yen CC, Yang CY, Lin-Shiau SY, Liu SH. Methylmercury induces pancreatic beta-cell apoptosis and dysfunction. Chem Res Toxicol 2006; 19:1080-5. [PMID: 16918248 DOI: 10.1021/tx0600705] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mercury is a well-known toxic metal, which induces oxidative stress. Pancreatic beta-cells are vulnerable to oxidative stress. The pathophysiological effect of mercury on the function of pancreatic beta-cells remains unclear. The present study was designed to investigate the effects of methylmercury (MeHg)-induced oxidative stress on the cell viability and function of pancreatic beta-cells. The number of viable cells was reduced 24 h after MeHg treatment in a dose-dependent manner with a range from 1 to 20 microM. 2',7'-Dichlorofluorescein fluorescence as an indicator of reactive oxygen species (ROS) formation after exposure of HIT-T15 cells or isolated mouse pancreatic islets to MeHg significantly increased ROS levels. MeHg could also suppress insulin secretion in HIT-T15 cells and isolated mouse pancreatic islets. After 24 h of exposure to MeHg, HIT-T15 cells had a significant increase in mercury levels with a dose-dependent manner. Moreover, MeHg displayed several features of cell apoptosis including an increase of the sub-G1 population and annexin-V binding. Treatment of HIT-T15 cells with MeHg resulted in disruption of the mitochondrial membrane potential and release of cytochrome c from the mitochondria to the cytosol and activation of caspase-3. Antioxidant N-acetylcysteine effectively reversed the MeHg-induced cellular responses. Altogether, our data clearly indicate that MeHg-induced oxidative stress causes pancreatic beta-cell apoptosis and dysfunction.
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Affiliation(s)
- Ya Wen Chen
- Institute of Toxicology, Department of Laboratory Medicine, and Department of Orthopaedics, College of Medicine, National Taiwan University, Taipei, Taiwan
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1015
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Meng XM, Liu L, Hu HY, Zhu MZ, Wang MX, Shi J, Guo QX. Highly sensitive and selective fluorescent chemosensors for Hg(II) in an aqueous environment based on carbamodithioate. Tetrahedron Lett 2006. [DOI: 10.1016/j.tetlet.2006.08.127] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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1016
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Ko SK, Yang YK, Tae J, Shin I. In Vivo Monitoring of Mercury Ions Using a Rhodamine-Based Molecular Probe. J Am Chem Soc 2006; 128:14150-5. [PMID: 17061899 DOI: 10.1021/ja065114a] [Citation(s) in RCA: 377] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Exposure to mercury causes severe damage to various tissues and organs in humans. Concern over mercury toxicity has encouraged the development of efficient, sensitive, and selective methods for the in vivo detection of mercury. Although a variety of chemosensors have been exploited for this purpose, no in vivo monitoring systems have been described to date. In this report, we describe an irreversible rhodamine chemosensor-based, real-time monitoring system to detect mercury ions in living cells and, in particular, vertebrate organisms. The chemosensor responds rapidly, irreversibly, and stoichiometrically to mercury ions in aqueous media at room temperature. The results of experiments with mammalian cells and zebrafish show that the mercury chemosensor is cell and organism permeable and that it responds selectively to mercury ions over other metal ions. In addition, real-time monitoring of mercury-ion uptake by cells and zebrafish using this chemosensor shows that saturation of mercury-ion uptake occurs within 20-30 min in cells and organisms. Finally, accumulation of mercury ions in zebrafish tissue and organs is readily detected by using this rhodamine-based chemosensor.
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Affiliation(s)
- Sung-Kyun Ko
- Department of Chemistry, Yonsei University, Seoul 120-749, Korea
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1017
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Fillion M, Mergler D, Passos CJS, Larribe F, Lemire M, Guimarães JRD. A preliminary study of mercury exposure and blood pressure in the Brazilian Amazon. Environ Health 2006; 5:29. [PMID: 17032453 PMCID: PMC1617089 DOI: 10.1186/1476-069x-5-29] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2005] [Accepted: 10/10/2006] [Indexed: 05/12/2023]
Abstract
BACKGROUND Fish is considered protective for coronary heart disease (CHD), but mercury (Hg) intake from fish may counterbalance beneficial effects. Although neurotoxic effects of methylmercury (MeHg) are well established, cardiovascular effects are still debated. The objective of the present study was to evaluate blood pressure in relation to Hg exposure and fish consumption among a non-indigenous fish-eating population in the Brazilian Amazon. METHODS The study was conducted among 251 persons from six communities along the Tapajós River, a major tributary of the Amazon. Data was obtained for socio-demographic information, fish consumption, height and weight to determine body mass index (BMI), systolic and diastolic blood pressure, and Hg concentration in hair samples. RESULTS Results showed that overall, systolic and diastolic blood pressure, were relatively low (mean: 113.9 mmHg +/- 14.6 and 73.7 mmHg +/- 11.0). Blood pressure was significantly associated with hair total Hg (H-Hg), age, BMI and gender. No association was observed between fish consumption and blood pressure, although there were significant inter-community differences. Logistic regression analyses showed that the Odds Ratio (OR) for elevated systolic blood pressure (> or = 130 mmHg) with H-Hg > or = 10 microg/g was 2.91 [1.26-7.28], taking into account age, BMI, smoking, gender and community. CONCLUSION The findings of this preliminary study add further support for Hg cardiovascular toxicity.
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Affiliation(s)
- Myriam Fillion
- Centre de recherche interdisciplinaire sur la biologie, la santé, la société et l'environnement (CINBIOSE), Université du Québec à Montréal, C.P. 8888, Succ. Centre-Ville, Montréal, Québec H3C 3P8, Canada
| | - Donna Mergler
- Centre de recherche interdisciplinaire sur la biologie, la santé, la société et l'environnement (CINBIOSE), Université du Québec à Montréal, C.P. 8888, Succ. Centre-Ville, Montréal, Québec H3C 3P8, Canada
| | - Carlos José Sousa Passos
- Centre de recherche interdisciplinaire sur la biologie, la santé, la société et l'environnement (CINBIOSE), Université du Québec à Montréal, C.P. 8888, Succ. Centre-Ville, Montréal, Québec H3C 3P8, Canada
| | - Fabrice Larribe
- Département de Mathématiques, Université du Québec à Montréal, C.P. 8888, Succ. Centre-Ville, Montréal, Québec H3C 3P8, Canada
| | - Mélanie Lemire
- Centre de recherche interdisciplinaire sur la biologie, la santé, la société et l'environnement (CINBIOSE), Université du Québec à Montréal, C.P. 8888, Succ. Centre-Ville, Montréal, Québec H3C 3P8, Canada
| | - Jean Rémy Davée Guimarães
- Laboratório de Traçadores, Instituto de Biofísica, Universidade Federal do Rio de Janeiro, Bloco G, CCS, Ilha do Fundão, Rio de Janeiro (RJ), CEP 21949-900, Brasil
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1018
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Kang MS, Jeong JY, Seo JH, Jeon HJ, Jung KM, Chin MR, Moon CK, Bonventre JV, Jung SY, Kim DK. Methylmercury-induced toxicity is mediated by enhanced intracellular calcium through activation of phosphatidylcholine-specific phospholipase C. Toxicol Appl Pharmacol 2006; 216:206-15. [PMID: 16854443 DOI: 10.1016/j.taap.2006.04.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 04/09/2006] [Accepted: 04/28/2006] [Indexed: 11/16/2022]
Abstract
Methylmercury (MeHg) is a ubiquitous environmental toxicant to which humans can be exposed by ingestion of contaminated food. MeHg has been suggested to exert its toxicity through its high reactivity to thiols, generation of arachidonic acid and reactive oxygen species (ROS), and elevation of free intracellular Ca(2+) levels ([Ca(2+)](i)). However, the precise mechanism has not been fully defined. Here we show that phosphatidylcholine-specific phospholipase C (PC-PLC) is a critical pathway for MeHg-induced toxicity in MDCK cells. D609, an inhibitor of PC-PLC, significantly reversed the toxicity in a time- and dose-dependent manner with concomitant inhibition of the diacylglycerol (DAG) generation and the phosphatidylcholine (PC)-breakdown. MeHg activated the group IV cytosolic phospholipase A(2) (cPLA(2)) and acidic form of sphingomyelinase (A-SMase) downstream of PC-PLC, but these enzymes as well as protein kinase C (PKC) were not linked to the toxicity by MeHg. Furthermore, MeHg produced ROS, which did not affect the toxicity. Addition of EGTA to culture media resulted in partial decrease of [Ca(2+)](i) and partially blocked the toxicity. In contrast, when the cells were treated with MeHg in the presence of Ca(2+) in the culture media, D609 completely prevented cell death with parallel decrease in [Ca(2+)](i). Our results demonstrated that MeHg-induced toxicity was linked to elevation of [Ca(2+)](i) through activation of PC-PLC, but not attributable to the signaling pathways such as cPLA(2), A-SMase, and PKC, or to the generation of ROS.
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Affiliation(s)
- Mi Sun Kang
- Department of Environmental and Health Chemistry, College of Pharmacy, Chung-Ang University, Seoul, 221 Huksuk-Dong, Dongjak-Ku, Seoul 156-756, South Korea
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1019
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Franco JL, Teixeira A, Meotti FC, Ribas CM, Stringari J, Garcia Pomblum SC, Moro AM, Bohrer D, Bairros AV, Dafre AL, Santos ARS, Farina M. Cerebellar thiol status and motor deficit after lactational exposure to methylmercury. ENVIRONMENTAL RESEARCH 2006; 102:22-8. [PMID: 16564521 DOI: 10.1016/j.envres.2006.02.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Revised: 01/27/2006] [Accepted: 02/08/2006] [Indexed: 05/08/2023]
Abstract
This study examined the exclusive contribution of methylmercury (MeHg) exposure through maternal milk on biochemical parameters related to the thiol status (glutathione (GSH) levels, glutathione peroxidase (GPx) and glutathione reductase (GR) activities) in the cerebellums of suckling mice. The same biochemical parameters were also evaluated in the cerebellums of mothers, which were submitted to a direct oral exposure to MeHg (10 mg/L in drinking water). With regard to the relationship between cerebellar function and motor activity, the presence of signs of motor impairment was also evaluated in the offspring exposed to MeHg during lactation. After the treatment (at weaning period), the pups lactationally exposed to MeHg showed increased levels of mercury in the cerebellum compared to pups in the control group and a significant impairment in the motor performance in the rotarod apparatus. In addition, these pups showed decreased levels of GSH in the cerebellum compared to pups in the control group. In dams, MeHg significantly increased the levels of cerebellar GSH and the activities of cerebellar GR. However, this was not observed in pups. This study indicates that (1) the exposure of lactating mice to MeHg causes significant impairments in motor performance in the offspring which may be related to a decrease in the cerebellar thiol status and (2) the increased GSH levels and GR activity, observed only in the cerebellums of MeHg-exposed dams, could represent compensatory pathophysiologic responses to the oxidative effects of MeHg toward endogenous GSH.
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Affiliation(s)
- Jeferson L Franco
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil
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1020
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KINGHORN APRIL, HUMPHRIES MURRAY, OUTRIDGE PETER, MAN CHAN HING. RECONSTRUCTING HISTORICAL MERCURY EXPOSURE FROM BELUGA WHALE CONSUMPTION AMONG INUIT IN THE MACKENZIE DELTA. J ETHNOBIOL 2006. [DOI: 10.2993/0278-0771(2006)26[310:rhmefb]2.0.co;2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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1021
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Jarosinska D, Barregård L, Biesiada M, Muszynska-Graca M, Dabkowska B, Denby B, Pacyna J, Fudala J, Zielonka U. Urinary mercury in adults in Poland living near a chloralkali plant. THE SCIENCE OF THE TOTAL ENVIRONMENT 2006; 368:335-43. [PMID: 16253310 DOI: 10.1016/j.scitotenv.2005.09.069] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2004] [Revised: 08/10/2005] [Accepted: 09/12/2005] [Indexed: 05/05/2023]
Abstract
We conducted a study within the framework of the interdisciplinary European Mercury Emission from Chloralkali Plants (EMECAP) project to assess exposure to mercury (Hg) and the contribution of Hg emissions from a mercury cell chloralkali plant to urinary mercury (U-Hg) in adults living near the plant. We collected data from questionnaires and first morning urine samples from 75 subjects living near the Tarnow plant in Poland and 100 subjects living in a reference area. Median U-Hg was 0.32 mug/g creatinine (microg/gC) and 0.20 microg/gC, respectively. The median U-Hg was also higher in the amalgam-free subjects living near the plant (0.26 microg/gC) than in the reference group (0.18 microg/gC), but no such association was found in a multivariate analysis. There was a statistically significant positive association between U-Hg and number of teeth with amalgams, a negative association with age and a tendency towards higher U-Hg in female subjects. In the amalgam-free subjects there were statistically significant effects of female sex and fish consumption, and a negative association with age. The additional long-term average air Hg concentration from the plant, based on EMECAP environmental measurements and modelling, was estimated to be 1-3.5 ng/m(3) for the residential study area and should have a very small effect on U-Hg. The other Hg emission sources such as coal combustion facilities located nearby should be taken into account in assessing the overall impact of air Hg on U-Hg in this area.
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Affiliation(s)
- Dorota Jarosinska
- Institute of Occupational Medicine and Environmental Health, 13 Koscielna, 41-200 Sosnowiec, Poland.
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1022
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Gil S, Lavilla I, Bendicho C. Ultrasound-Promoted Cold Vapor Generation in the Presence of Formic Acid for Determination of Mercury by Atomic Absorption Spectrometry. Anal Chem 2006; 78:6260-4. [PMID: 16944910 DOI: 10.1021/ac0606498] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new cold vapor technique within the context of green chemistry is described for determination of mercury in liquid samples following high-intensity ultrasonication. Volatile Hg evolved in a sonoreactor without the use of a chemical reducing agent is carried to a quartz cell kept at room temperature for measurement of the atomic absorption. The mechanism involved lies in the reduction of Hg(II) to Hg(0) by reducing gases formed upon sonication and subsequent volatilization of Hg(0) due to the degassing effect caused by the cavitation phenomenon. Addition of a low molecular weight organic acid such as formic acid favors the process, but vapor generation also occurs from Hg solutions in ultrapure water. The detection limit of Hg was 0.1 microg/L, and the repeatability, expressed as relative standard deviation, was 4.4% (peak height). Addition of small amounts of oxidizing substances such as the permanganate or dichromate anions completely suppressed the formation of Hg(0), which confirms the above mechanism. Effect of other factors such as ultrasound irradiation time, ultrasound amplitude, and the presence of concomitants are also investigated. Some complexing anions such as chloride favored the stabilization of Hg(II) in solution, hence causing an interference effect on the ultrasound-assisted reduction/volatilization process.
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Affiliation(s)
- Sandra Gil
- Departamento de Química Analítica y Alimentaria, Area de Química Analítica, Facultad de Química, Universidad de Vigo, Campus As Lagoas-Marcosende s/n, 36310 Vigo, Spain
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1023
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Guzzi G, Grandi M, Cattaneo C, Calza S, Minoia C, Ronchi A, Gatti A, Severi G. Dental amalgam and mercury levels in autopsy tissues: food for thought. Am J Forensic Med Pathol 2006; 27:42-5. [PMID: 16501347 DOI: 10.1097/01.paf.0000201177.62921.c8] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Eighteen cadavers from routine autopsy casework were subject to a study of tissue levels of total mercury in brain, thyroid, and kidney samples by atomic absorption. On these same cadavers, all dental amalgam fillings (the most important source of inorganic mercury exposure in the general population, according to the World Health Organization (WHO) were charted. Total mercury levels were significantly higher in subjects with a greater number of occlusal amalgam surfaces (>12) compared with those with fewer occlusal amalgams (0-3) in all types of tissue (all P < or = 0.04). Mercury levels were significantly higher in brain tissues compared with thyroid and kidney tissues in subjects with more than 12 occlusal amalgam fillings (all P < or = 0.01) but not in subjects with 3 or less occlusal amalgams (all P > or = 0.07).
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Affiliation(s)
- Gianpaolo Guzzi
- Italian Association for Metals and Biocompatibility Research (AIRMEB), Milan, Italy
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1024
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Freire MAM, Oliveira RB, Picanço-Diniz CW, Pereira A. Differential effects of methylmercury intoxication in the rat's barrel field as evidenced by NADPH diaphorase histochemistry. Neurotoxicology 2006; 28:175-81. [PMID: 16930717 DOI: 10.1016/j.neuro.2006.06.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 06/20/2006] [Accepted: 06/22/2006] [Indexed: 10/24/2022]
Abstract
In the present study, we investigated the effects of mercury intoxication on the structure of the posteromedial barrel subfield (PMBSF) in the primary somatosensory cortex (SI) of adult rats, as revealed by histochemical reactivity to the enzyme NADPH diaphorase (NADPH-d). Enzymatic reactivity in the neuropil inside barrels was drastically reduced in intoxicated animals, suggesting that the synthesis and/or transport of the nitric oxide synthase enzyme can be altered in acute mercury intoxication. However, the cell bodies and dendrites of barrel neurons, also strongly reactive to the enzyme, were spared from the mercury's deleterious effects.
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Affiliation(s)
- Marco Aurélio M Freire
- Laboratory of Functional Neuroanatomy, Department of Morphology, Federal University of Pará, Belém 66075-900, PA, Brazil.
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1025
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Latshaw MW, Glass T, Parsons P, Hidalgo J, Schwartz B. Predictors of Blood Mercury Levels in Older Urban Residents. J Occup Environ Med 2006; 48:715-22. [PMID: 16832229 DOI: 10.1097/01.jom.0000205208.85800.70] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The objective of this study was to describe the distribution and predictors of blood mercury levels in an adult population. METHODS This was a cross-sectional analysis of first-visit data (2001-2002) on a random sample of 474 subjects from the Baltimore Memory Study. RESULTS After adjustment for race/ethnicity, education, assets, and diabetes, persons in the highest quartile of fish consumption had median mercury levels 1.82 times above the levels in the lowest quartile, while those in the highest education category had median mercury levels 1.57 times higher than levels in the lowest category. Nine percent of subjects were above the reference dose recommended by the Environmental Protection Agency, which is high compared with that found by the Centers for Disease Control and Prevention in women of childbearing age. CONCLUSIONS These findings offer guidance for targeted education and possible new insights regarding the kinetics of mercury.
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Affiliation(s)
- Megan Weil Latshaw
- Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA.
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1026
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Cummings CE, Rosenman KD. Ulcerative colitis reactivation after mercury vapor inhalation. Am J Ind Med 2006; 49:499-502. [PMID: 16691608 DOI: 10.1002/ajim.20306] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND After exposure to mercury vapor at three consecutive 10-month intervals, an electrician in an electroplating plant had flare-ups of ulcerative colitis within 24 hr, that subsided in several days, then returned upon re-exposure 10 months later. METHODS The patient and his workplace were both evaluated for mercury exposure. In addition to workplace inspection, both personal and area monitoring for environmental mercury was performed, using both multiple mercury diffusion badges and direct (instantaneous) readings, during maintenance of mercury-filled electrical blocks. RESULTS Eight-hour time weighted average (TWA) mercury vapor exposure was measured at 0.41 mg/m3 (ACGIH and NIOSH recommended TWA = 0.025 mg/m3; OSHA permissible exposure limit -0.1 mg/m3) for 5 years since stopping overexposure to mercury, the patient remained symptom free in clinical remission. CONCLUSIONS In a patient with chronic ulcerative colitis in remission, occupational exposure to mercury vapor led to episodes of disease reactivation.
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Affiliation(s)
- Curtis E Cummings
- Department of Environmental and Occupational Health, School of Public Health, Drexel University, Philadelphia, Pennsylvania 19102-1192, USA.
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1027
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Chen YW, Huang CF, Tsai KS, Yang RS, Yen CC, Yang CY, Lin-Shiau SY, Liu SH. The role of phosphoinositide 3-kinase/Akt signaling in low-dose mercury-induced mouse pancreatic beta-cell dysfunction in vitro and in vivo. Diabetes 2006; 55:1614-24. [PMID: 16731823 DOI: 10.2337/db06-0029] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The relationship between oxidation stress and phosphoinositide 3-kinase (PI3K) signaling in pancreatic beta-cell dysfunction remains unclear. Mercury is a well-known toxic metal that induces oxidative stress. Submicromolar-concentration HgCl(2) or methylmercury triggered reactive oxygen species (ROS) production and decreased insulin secretion in beta-cell-derived HIT-T15 cells and isolated mouse islets. Mercury increased PI3K activity and its downstream effector Akt phosphorylation. Antioxidant N-acetyl-l-cysteine (NAC) prevented mercury-induced insulin secretion inhibition and Akt phosphorylation but not increased PI3K activity. Inhibition of PI3K/Akt activity with PI3K inhibitor or by expressing the dominant-negative p85 or Akt prevented mercury-induced insulin secretion inhibition but not ROS production. These results indicate that both PI3K and ROS independently regulated Akt signaling-related, mercury-induced insulin secretion inhibition. We next observed that 2- or 4-week oral exposure to low-dose mercury to mice significantly caused the decrease in plasma insulin and displayed the elevation of blood glucose and plasma lipid peroxidation and glucose intolerance. Akt phosphorylation was shown in islets isolated from mercury-exposed mice. NAC effectively antagonized mercury-induced responses. Mercury-induced in vivo effects and increased blood mercury were reversed after mercury exposure was terminated. These results demonstrate that low-dose mercury-induced oxidative stress and PI3K activation cause Akt signaling-related pancreatic beta-cell dysfunction.
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Affiliation(s)
- Ya Wen Chen
- Institute of Toxicology, College of Medicine, National Taiwan University, No. 1, Section 1, Jen-Ai Road, Taipei, 10043, Taiwan
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1028
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Stringari J, Meotti FC, Souza DO, Santos ARS, Farina M. Postnatal methylmercury exposure induces hyperlocomotor activity and cerebellar oxidative stress in mice: dependence on the neurodevelopmental period. Neurochem Res 2006; 31:563-9. [PMID: 16758366 DOI: 10.1007/s11064-006-9051-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/31/2006] [Indexed: 10/24/2022]
Abstract
During the early postnatal period the central nervous system (CNS) is extremely sensitive to external agents. The present study aims at the investigation of critical phases where methylmercury (MeHg) induces cerebellar toxicity during the suckling period in mice. Animals were treated with daily subcutaneous injections of MeHg (7 mg/kg of body weight) during four different periods (5 days each) at the early postnatal period: postnatal day (PND) 1-5, PND 6-10, PND 11-15, or PND 16-20. A control group was treated with daily subcutaneous injections of a 150 mM NaCl solution (10 ml/kg of body weight). Subjects exposed to MeHg at different postnatal periods were littermate. At PND 35, behavioral tests were performed to evaluate spontaneous locomotor activity in the open field and motor performance in the rotarod task. Biochemical parameters related to oxidative stress (levels of glutathione and thiobarbituric acid reactive substances, as well as glutathione peroxidase and glutathione reductase activity) were evaluated in cerebellum. Hyperlocomotor activity and high levels of cerebellar thiobarbituric acid reactive substances were observed in animals exposed to MeHg during the PND 11-15 or PND 16-20 periods. Cerebellar glutathione reductase activity decreased in MeHg-exposed animals. Cerebellar glutathione peroxidase activity was also decreased after MeHg exposure and the lowest enzymatic activity was found in animals exposed to MeHg during the later days of the suckling period. In addition, low levels of cerebellar glutathione were found in animals exposed to MeHg during the PND 16-20 period. The present results show that the postnatal exposure to MeHg during the second half of the suckling period causes hyperlocomotor activity in mice and point to this phase as a critical developmental stage where mouse cerebellum is a vulnerable target for the neurotoxic and pro-oxidative effects of MeHg.
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Affiliation(s)
- James Stringari
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Brazil
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1029
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Dalvie MA, Ehrlich R. Community mercury levels in the vicinity of peri-urban waste disposal sites and fossil fuel burning operations. ENVIRONMENT INTERNATIONAL 2006; 32:493-9. [PMID: 16434098 DOI: 10.1016/j.envint.2005.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2005] [Revised: 11/16/2005] [Accepted: 11/22/2005] [Indexed: 05/06/2023]
Abstract
INTRODUCTION A study was conducted as a result of concern about mercury absorption amongst residents of a peri-urban area in Cape Town, South Africa, in close proximity to waste disposal sites and an industrial area. STUDY METHODS The study compared urine mercury concentrations in a random sample of adult residents and children in both the formal and informal housing settlements of the "exposure" area (n = 90) and a control area (n = 90). A short questionnaire elicited demographic, lifestyle and medical details and possible occupational, household and environmental mercury exposures. RESULTS The two samples were comparable with respect to background and potential confounding variables. The prevalence of urinary mercury levels>or=the WHO reference range in the exposure area was also higher than that in the control area (13% vs. 0%). The median urinary mercury concentrations in both study areas were below the World Health Organisation (WHO) reference level of 5.0 microg/g creatinine. The median level in the exposure area was slightly, but statistically significantly, higher than in the control area (1.1 vs. 0.25 microg/g creatinine), and the excess persisted after controlling for known possible mercury exposures. CONCLUSIONS This is to our knowledge the first study of community inorganic mercury absorption in a developing country setting, and where airborne mercury was the exposure of concern. It was concluded that the health risk associated with the urinary mercury levels of residents in the exposure area was very low. However, low level environmental exposure in the area of concern could not be excluded.
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Affiliation(s)
- Mohamed A Dalvie
- Occupational and Environmental Health Research Unit, School of Public Health and Family Medicine, Health Sciences Faculty, University of Cape Town, Anzio Road, Observatory, 7925, Cape Town, South Africa.
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1030
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Abstract
While there is a significant amount of data showing health benefits of increased fish consumption, there are conflicting reports about the cardiovascular risks of mercury in seafood. A recent long-term study attempted to resolve this controversy, providing an opportunity to balance recommendations from the US Environmental Protection Agency for mercury with those from the American Heart Association for fish consumption.
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Affiliation(s)
- Cathy W Levenson
- Program in Neuroscience and the Department of Nutrition, Food & Exercise Sciences, Florida State University, Tallahassee, Florida 32306-4340, USA.
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1031
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Ibrahim D, Froberg B, Wolf A, Rusyniak DE. Heavy Metal Poisoning: Clinical Presentations and Pathophysiology. Clin Lab Med 2006; 26:67-97, viii. [PMID: 16567226 DOI: 10.1016/j.cll.2006.02.003] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Humans have had a long and tumultuous relationship with heavy metals. Their ubiquitous nature and our reliance on them for manufacturing have resulted at times in exposures sufficient to cause systemic toxicity. Their easy acquisition and potent toxicity have also made them popular choices for criminal poisonings. This article examines the clinical manifestation and pathophysiology of poisoning from lead, mercury, arsenic, and thallium.
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Affiliation(s)
- Danyal Ibrahim
- Department of Emergency Medicine, Division of Medical Toxicology, Indiana University School of Medicine, 1050 Wishard Boulevard, Room 2200, Indianapolis, IN 46202, USA
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1032
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Abstract
Omega-3 fatty acids are a subset of polyunsaturated fatty acids found in marine sources as eicosapentaenoic acid and docosahexaenoic acid and in some leafy vegetables, nuts, and oils as alpha-linolenic acid (ALA). The metabolism of omega-3's may explain the cardioprotective effects observed in epidemiologic and experimental studies. Although most data for cardioprotective effects come from studies of marine sources, vegetable sources of omega-3 fatty acids (alpha-linolenic acid) may have similar effects through in vivo conversion to eicosapentaenoic acid and docosahexaenoic acid. This document will provide an overview of omega-3 fatty acids with a focus on specific sources, metabolism, safety issues, and their potential indication for cardiovascular prevention.
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Affiliation(s)
- Andrew P DeFilippis
- Division of General Medicine, Emory University School of Medicine, Atlanta, GA 30303, USA.
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1033
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Garg TK, Chang JY. Methylmercury causes oxidative stress and cytotoxicity in microglia: Attenuation by 15-deoxy-delta 12, 14-Prostaglandin J2. J Neuroimmunol 2006; 171:17-28. [PMID: 16225932 DOI: 10.1016/j.jneuroim.2005.09.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2005] [Accepted: 09/13/2005] [Indexed: 11/23/2022]
Abstract
Methylmercury (MeHg) causes severe neurological disorders in the central nervous system. This study focused on the effects of MeHg on microglia, macrophage-like cells that reside in the CNS important in neuro-immune interactions. The murine N9 microglial cell line was used in this set of study. MeHg caused reactive oxygen species generation, mitochondrial depolarization and aconitase inactivation, all of which were signs of cellular oxidative stress. MeHg greatly increased microglial IL-6 secretion despite the fact that it severely inhibited protein synthesis. The concentration that caused 50% cell death in 24 h was approximately 9 microM. Pretreatment of microglia with the prostaglandin derivative, 15-deoxy-delta 12, 14-Prostaglandin J2 attenuated MeHg induced cell death. The saving effect did not appear to be mediated through activation of peroxisome proliferator activated receptors (PPAR) since other agonists of these receptors did not prevent MeHg induced microglial death.
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Affiliation(s)
- Tarun K Garg
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, 4301 W. Markham St., Little Rock, AR 72205, USA
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1034
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Hutton EA, Ogorevc B, Hočevar SB, Smyth MR. Bismuth film microelectrode for direct voltammetric measurement of trace cobalt and nickel in some simulated and real body fluid samples. Anal Chim Acta 2006. [DOI: 10.1016/j.aca.2005.10.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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1035
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Clements CJ, McIntyre PB. When science is not enough – a risk/benefit profile of thiomersal-containing vaccines. Expert Opin Drug Saf 2005; 5:17-29. [PMID: 16370953 DOI: 10.1517/14740338.5.1.17] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Without a preservative, such as thiomersal (known as thimerosal in the US), multi-dose liquid presentations of vaccine are vulnerable to bacteriological contamination that can result in death or serious illness of the recipient. Concerns about levels of mercury exposure from thiomersal-containing vaccines were first raised in the US during 1999 in the context of Hepatitis B vaccine for newborns. Since then, a large body of evidence from animal and epidemiological studies has accumulated on the safety of thiomersal. Ironically, these data have become largely irrelevant in wealthy countries, where mono-dose, thiomersal-free vaccines have been introduced as a precautionary measure in almost all childhood vaccines, in part related to residual public scepticism. In poor countries, multi-dose vials remain important for vaccine delivery. There is a real danger that this controversy may result in the loss to the world of thiomersal as a preservative, simply from popular pressure. In reality, it would be impossible to cease overnight using thiomersal and maintain the supply of vital vaccines. This paper reviews and summarises the data available from published studies on mercury toxicity, and thiomersal in vaccines in particular, that overwhelmingly indicate continued use of thiomersal is safe in those countries where it is most needed.
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Affiliation(s)
- C John Clements
- Centre for International Health, The Macfarlane Burnet Institute for Medical Research and Public Health Ltd, GPO Box 2284, Commercial Road, Melbourne, VIC 3004, Australia.
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1036
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Affiliation(s)
- Samuel J Spiegel
- Department of Mining Engineering, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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1037
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Tarabová B, Kurejová M, Sulová Z, Drabová M, Lacinová L. Inorganic Mercury and Methylmercury Inhibit the Cav3.1 Channel Expressed in Human Embryonic Kidney 293 Cells by Different Mechanisms. J Pharmacol Exp Ther 2005; 317:418-27. [PMID: 16326920 DOI: 10.1124/jpet.105.095463] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Part of the neurotoxic effects of inorganic mercury (Hg(2+)) and methylmercury (MeHg) was attributed to their interaction with voltage-activated calcium channels. Effects of mercury on T-type calcium channels are controversial. Therefore, we investigated effects of Hg(2+) and MeHg on neuronal Ca(v)3.1 (T-type) calcium channel stably expressed in the human embryonic kidney (HEK) 293 cell line. Hg(2+) acutely inhibited current through the Ca(v)3.1 calcium channel in concentrations 10 nM and higher with an IC(50) of 0.63 +/- 0.11 microM and a Hill coefficient of 0.73 +/- 0.08. Inhibition was accompanied by strong deceleration of current activation, inactivation, and deactivation. The current-voltage relation was broadened, and its peak was shifted to a more depolarized membrane potentials by 1 microM Hg(2+). MeHg in concentrations between 10 nM and 100 microM inhibited the current through the Ca(v)3.1 calcium channel with an IC(50) of 13.0 +/- 5.0 microM and a Hill coefficient of 0.47 +/- 0.09. Low concentration of MeHg (10 pM to 1 nM) had both positive and negative effects on the current amplitude. Micromolar concentrations of MeHg reduced the speed of current activation and accelerated current inactivation and deactivation. The current-voltage relation was not affected. Up to 72 h of exposure to 10 nM MeHg had no significant effect on current amplitude, whereas 72-h-long exposure to 1 nM MeHg increased significantly current density. Acute treatment with Hg(2+) or MeHg did not affect HEK 293 cell viability. In conclusion, interaction with the Ca(v)3.1 calcium channel may significantly contribute to neuronal symptoms of mercury poisoning during both acute poisoning and long-term environmental exposure.
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Affiliation(s)
- Bohumila Tarabová
- Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava
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1038
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Moretto MB, Funchal C, Santos AQ, Gottfried C, Boff B, Zeni G, Pureur RP, Souza DO, Wofchuk S, Rocha JBT. Ebselen protects glutamate uptake inhibition caused by methyl mercury but does not by Hg2+. Toxicology 2005; 214:57-66. [PMID: 16011868 DOI: 10.1016/j.tox.2005.05.022] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Revised: 05/19/2005] [Accepted: 05/29/2005] [Indexed: 11/26/2022]
Abstract
Alterations of the neurotransmitter release systems in CNS have been reported in a variety of neuropathological processes associated with heavy metal toxicity. Neurotoxic effects of mercurials were investigated in vitro in cerebral cortex slices from young rats. The present study indicates that: (i) the environmental contaminants methylmercury (MeHg) and mercuric chloride (Hg2+) (50 microM) inhibited the glutamate net uptake from the cerebral cortex of 17-day-old rats; (ii) ebselen (10 microM) reverted the MeHg-induced inhibition of glutamate net uptake but did not protect the inhibition caused by Hg2+. At same time, we investigated another diorganochalcogenide, diphenyl diselenide (PhSe)2 and it was observed that this compound did not revert the action of MeHg or Hg2+; (iii) in addition, we observed that exposure of slices to 50 microM MeHg and Hg2+ for 30 min followed by Trypan blue exclusion assay resulted in 58.5 and 67.5% of staining cells, respectively, indicating a decrease in cell viability. Ebselen protected slices from the deleterious effects of MeHg, but not of Hg2+ on cell viability. Conversely, ebselen did not modify the reduction of MTT caused by MeHg and Hg2+; (iv) the protective effect of ebselen on MeHg-induced inhibition of glutamate net uptake seems to be related to its ability in maintaining cell viability.
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Affiliation(s)
- M B Moretto
- Departamento de Análises Clínicas e Toxicológicas, Centro de Ciências da Saúde, Universidade Federal de Santa Maria, RS, Brazil
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1039
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Yoon S, Albers AE, Wong AP, Chang CJ. Screening Mercury Levels in Fish with a Selective Fluorescent Chemosensor. J Am Chem Soc 2005; 127:16030-1. [PMID: 16287282 DOI: 10.1021/ja0557987] [Citation(s) in RCA: 458] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Societal concerns over toxic mercury accumulation in humans from fish and other dietary and environmental sources provide motivation to develop new tools and tactics for mercury detection in a wide range of laboratory and field settings. Here we report the synthesis, properties, and application of a selective and sensitive small-molecule chemosensor for fluorescence screening of mercury levels in fish. Mercuryfluor-1 (MF1) is a water-soluble, fluorescein-based reagent that features excellent selectivity for Hg2+ over competing analytes and the largest turn-on fluorescence response to date (>170-fold increase) for reporting this heavy metal ion in aqueous solution. Combining this chemoselective Hg2+ probe with a microwave digestion protocol provides a facile method for assaying mercury levels in fish samples with mercury concentrations spanning 0.1 to 8 ppm, a range well matched with the United States Environmental Protection Agency (U.S. EPA) standard for the maximum safe level of mercury in edible fish (0.55 ppm).
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Affiliation(s)
- Sungho Yoon
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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1040
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Wolf PL. The effects of diseases, drugs, and chemicals on the creativity and productivity of famous sculptors, classic painters, classic music composers, and authors. Arch Pathol Lab Med 2005; 129:1457-64. [PMID: 16253027 DOI: 10.5858/2005-129-1457-teodda] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
CONTEXT Many myths, theories, and speculations exist as to the exact etiology of the diseases, drugs, and chemicals that affected the creativity and productivity of famous sculptors, classic painters, classic music composers, and authors. OBJECTIVE To emphasize the importance of a modern clinical chemistry laboratory and hematology coagulation laboratory in interpreting the basis for the creativity and productivity of various artists. DESIGN This investigation analyzed the lives of famous artists, including classical sculptor Benvenuto Cellini; classical sculptor and painter Michelangelo Buonarroti; classic painters Ivar Arosenius, Edvard Munch, and Vincent Van Gogh; classic music composer Louis Hector Berlioz; and English essayist Thomas De Quincey. The analysis includes their illnesses, their famous artistic works, and the modern clinical chemistry, toxicology, and hematology coagulation tests that would have been important in the diagnosis and treatment of their diseases. CONCLUSIONS The associations between illness and art may be close and many because of both the actual physical limitations of the artists and their mental adaptation to disease. Although they were ill, many continued to be productive. If modern clinical chemistry, toxicology, and hematology coagulation laboratories had existed during the lifetimes of these various well-known individuals, clinical laboratories might have unraveled the mysteries of their afflictions. The illnesses these people endured probably could have been ascertained and perhaps treated. Diseases, drugs, and chemicals may have influenced their creativity and productivity.
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Affiliation(s)
- Paul L Wolf
- Department of Pathology and Laboratory Medicine, University of California, VA Medical Center, San Diego, CA 92103, USA.
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1041
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Risher JF, Amler SN. Mercury exposure: evaluation and intervention the inappropriate use of chelating agents in the diagnosis and treatment of putative mercury poisoning. Neurotoxicology 2005; 26:691-9. [PMID: 16009427 DOI: 10.1016/j.neuro.2005.05.004] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2005] [Indexed: 10/25/2022]
Abstract
Public awareness of the potential for mercury to cause health problems has increased dramatically in the last 15 years. It is now widely recognized that significant exposure to all forms of mercury (elemental/metallic and both inorganic and organic compounds) can result in a variety of adverse health effects, including neurological, renal, respiratory, immune, dermatologic, reproductive, and developmental sequellae. And while the various media have made the general population cognizant of the need to avoid unnecessary exposure to this naturally occurring element, there has also evolved a growing tendency to attribute unexplainable neurologic, as well as other, signs and symptoms to mercury, whether or not significant exposure to mercury has actually occurred. For the physician, making a diagnosis of mercury intoxication can be difficult, because many of the clinical signs and symptoms of mercury exposure can also be attributed to any number of causes, including undiagnosed neurological diseases, pharmacotherapy, vitamin or mineral deficiencies, and psychological stress. The physician must be able to recognize the clinical manifestations of mercury intoxication, and understand the importance of biological markers in making a definitive diagnosis of mercury poisoning. In a desire to treat the patient complaining of symptoms similar to some that can be caused by mercury, a growing number of physicians, particularly those in alternative medicine fields, result to chelation to "rid" the body of the mercury, believed to be the cause of the ailments. And although the use of chelation is increasing, controlled studies showing that this procedure actually improves outcome are lacking. If chelation therapy is considered to be indicated, the attending physician should communicate the risks of chelation to the patient before beginning treatment with metal-chelating drugs.
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Affiliation(s)
- John F Risher
- Agency for Toxic Substances and Disease Registry, Division of Toxicology (F-32), 1600 Clifton Road, Atlanta, GA 30333, USA.
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1042
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Pigatto PD, Guzzi G. Oral lichenoid lesions: More than mercury. ACTA ACUST UNITED AC 2005; 100:398-400. [PMID: 16182158 DOI: 10.1016/j.tripleo.2004.12.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2004] [Revised: 12/07/2004] [Accepted: 12/28/2004] [Indexed: 10/25/2022]
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1043
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Eisele K, Lang PA, Kempe DS, Klarl BA, Niemöller O, Wieder T, Huber SM, Duranton C, Lang F. Stimulation of erythrocyte phosphatidylserine exposure by mercury ions. Toxicol Appl Pharmacol 2005; 210:116-22. [PMID: 16137732 DOI: 10.1016/j.taap.2005.07.022] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Revised: 07/19/2005] [Accepted: 07/21/2005] [Indexed: 01/06/2023]
Abstract
The sequelae of mercury intoxication include induction of apoptosis. In nucleated cells, Hg2+-induced apoptosis involves mitochondrial damage. The present study has been performed to elucidate effects of Hg2+ in erythrocytes which lack mitochondria but are able to undergo apoptosis-like alterations of the cell membrane. Previous studies have documented that activation of a Ca2+-sensitive erythrocyte scramblase leads to exposure of phosphatidylserine at the erythrocyte surface, a typical feature of apoptotic cells. The erythrocyte scramblase is activated by osmotic shock, oxidative stress and/or energy depletion which increase cytosolic Ca2+ activity and/or activate a sphingomyelinase leading to formation of ceramide. Ceramide sensitizes the scramblase to Ca2+. The present experiments explored the effect of Hg2+ ions on erythrocytes. Phosphatidylserine exposure after mercury treatment was estimated from annexin binding as determined in FACS analysis. Exposure to Hg2+ (1 microM) indeed significantly increased annexin binding from 2.3+/-0.5% (control condition) to 23+/-6% (n=6). This effect was paralleled by activation of a clotrimazole-sensitive K+-selective conductance as measured by patch-clamp recordings and by transient cell shrinkage. Further experiments revealed also an increase of ceramide formation by approximately 66% (n=7) after challenge with mercury (1 microM). In conclusion, mercury ions activate a clotrimazole-sensitive K+-selective conductance leading to transient cell shrinkage. Moreover, Hg2+ increases ceramide formation. The observed mechanisms could similarly participate in the triggering of apoptosis in nucleated cells by Hg2+.
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Affiliation(s)
- Kerstin Eisele
- Department of Physiology, University of Tübingen, Germany
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1044
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Dye BA, Schober SE, Dillon CF, Jones RL, Fryar C, McDowell M, Sinks TH. Urinary mercury concentrations associated with dental restorations in adult women aged 16-49 years: United States, 1999-2000. Occup Environ Med 2005; 62:368-75. [PMID: 15901883 DOI: 10.1136/oem.2004.016832] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Mercury amalgam dental restorations have been used by dentists since the mid 19th century and issues on safety continue to be periodically debated within the scientific and public health communities. Previous studies have reported a positive association between urine mercury levels and the number of dental amalgams, but this relation has never been described in a nationally representative sample in the United States. AIMS AND METHODS Using household interview, dietary interview, dental examination, and laboratory data from the 1999-2000 National Health and Nutrition Examination Survey (NHANES), the association between mercury concentrations and dental restorations was examined in US women of reproductive age. RESULTS In women of childbearing age, approximately 13% of all posterior dental surfaces were restored with amalgams and the average urinary mercury level in women was low (1.34 microg/l). It is estimated that an increase of 1.8 microg/l in the log transformed values for mercury in urine would occur for each 10 dental surfaces restored with amalgam. CONCLUSIONS Although the findings do not address the important issues of adverse health effects at low thresholds of mercury exposure, they do provide important reference data that should contribute significantly to the ongoing scientific and public health policy debate on the use of dental amalgams in the USA.
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Affiliation(s)
- B A Dye
- Centers for Disease Control and Prevention/National Center for Health Statistics, Hyattsville, MD 20782, USA.
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1045
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Abstract
Children's health is, to a large extent, a function of their environment. Infectious agents remain the leading cause of death and disability in the world. In contrast, many of the new morbidities--asthma, intellectual impairments, behavioural problems, and cancer--are linked with industrial pollutants or other environmental influences. Our understanding of the risk factors for many diseases is incomplete, but it is widely recognised that disability and death result largely from interactions of environmental factors, broadly defined, and host susceptibility.
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Affiliation(s)
- B P Lanphear
- Cincinnati Children's Environmental Health Center, Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati, Cincinnati, Ohio, USA.
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1046
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Affiliation(s)
- Michael Aschner
- Department of Pediatrics and the Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2495, USA.
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1047
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Gonzalez P, Dominique Y, Massabuau JC, Boudou A, Bourdineaud JP. Comparative effects of dietary methylmercury on gene expression in liver, skeletal muscle, and brain of the zebrafish (Danio rerio). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2005; 39:3972-80. [PMID: 15984772 DOI: 10.1021/es0483490] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Effects of dietary methylmercury (MeHg) on gene expression were examined in three organs (liver, skeletal muscle, and brain) of the zebrafish (Danio rerio). Adult male fish were fed over 7, 21, and 63 days on three different diets: one control diet (C0: 0.08 microg of Hg g(-1), dry wt) and two diets (C1 and C2) contaminated by MeHg at 5 and 13.5 microg of Hg g(-1), dry wt. Total Hg and MeHg concentrations were determined in the three organs after each exposure duration, and a demethylation process was evidenced only in the liver. Thirteen genes known to be involved in antioxidant defenses, metal chelation, active efflux of organic compounds, mitochondrial metabolism, DNA repair, and apoptosis were investigated by quantitative real-time RT-PCR and normalized according to actin gene expression. Surprisingly, no change in the expression levels of these genes was observed in contaminated brain samples, although this organ accumulated the highest mercury concentration (63.5 +/- 4.4 microg g(-1), dry wt after 63 days). This lack of genetic response could explain the high neurotoxicity of MeHg. coxI and cytoplasmic and mitochondrial sod gene expressions were induced early in skeletal muscle and later in liver, indicating an impact on the mitochondrial metabolism and production of reactive oxygen species. Results demonstrated that skeletal muscle was not only an important storage reservoir but was also affected by MeHg contamination. The expression of the metallothionein mt2 and the DNA repair rad51 genes was up-regulated in liver between 21 and 63 days, whereas in skeletal muscle, mt2 remained uninduced, and gadd and rad51 were found to be repressed.
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Affiliation(s)
- P Gonzalez
- Laboratoire d'Ecophysiologie et Ecotoxicologie des Systèmes Aquatiques, Université Bordeaux 1/UMR CNRS 5805, Place du Dr Peyneau, 33120 Arcachon, France
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1048
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Kingman A, Albers JW, Arezzo JC, Garabrant DH, Michalek JE. Amalgam exposure and neurological function. Neurotoxicology 2005; 26:241-55. [PMID: 15713345 DOI: 10.1016/j.neuro.2004.09.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Accepted: 09/24/2004] [Indexed: 11/30/2022]
Abstract
Concerns regarding the safety of silver-mercury amalgam fillings continue to be raised in the absence of any direct evidence of harm. The widespread population exposure to amalgam mandated that a thorough investigation be conducted of its potential effects on the nervous system. The National Institute of Dental and Craniofacial Research and U.S. Air Force investigators collaborated in the ongoing Air Force Health Study (AFHS) of Vietnam era veterans. The primary study question involved adverse health effects associated with exposure to herbicides or dioxin. An assessment of exposure to dental amalgam fillings was added to the 1997-1998 health examination to investigate possible associations between amalgam exposure and neurological abnormalities. Our study population consisted of 1663 dentate AFHS participants, comprised of 986 AFHS controls and 677 Ranch Hand veterans who were exposed to dioxin in Vietnam. Two hundred and fifty-two of the participants had confirmed diabetes mellitus. Study outcomes included clinical neurological signs, vibrotactile thresholds, and summary variables for different levels of peripheral neuropathy. A limitation of our study is that our database did not include more sensitive continuous measures such as nerve conduction studies. No significant associations were found between amalgam exposure and clinical neurological signs of abnormal tremor, coordination, station or gait, strength, sensation, or muscle stretch reflexes or for any level of peripheral neuropathy among our study participants. A statistically significant association was detected between amalgam exposure and the continuous vibrotactile sensation response for the combined non-diabetic participants and separately for non-diabetic AFHS controls. No significant association in this measure was detectable for non-diabetic Ranch Hand veterans or among the combined diabetic participants. The association is a sub-clinical finding that was not associated with symptoms, clinically evident signs of neuropathy, or any functional impairment. Overall, we found no association between amalgam exposure and neurological signs or clinically evident peripheral neuropathy. Our findings do not support the hypothesis that exposure to amalgam produces adverse, clinically evident neurological effects.
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Affiliation(s)
- Albert Kingman
- Division of Clinical Research and Health Promotion, National Institute of Dental and Craniofacial Research, National Institutes of Health, 45 Center Drive, Room 4As-25U, Bethesda, MD 20892-6401, USA.
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1049
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Sweet DH. Organic anion transporter (Slc22a) family members as mediators of toxicity. Toxicol Appl Pharmacol 2005; 204:198-215. [PMID: 15845414 DOI: 10.1016/j.taap.2004.10.016] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Accepted: 10/21/2004] [Indexed: 01/11/2023]
Abstract
Exposure of the body to toxic organic anions is unavoidable and occurs from both intentional and unintentional sources. Many hormones, neurotransmitters, and waste products of cellular metabolism, or their metabolites, are organic anions. The same is true for a wide variety of medications, herbicides, pesticides, plant and animal toxins, and industrial chemicals and solvents. Rapid and efficient elimination of these substances is often the body's best defense for limiting both systemic exposure and the duration of their pharmacological or toxicological effects. For organic anions, active transepithelial transport across the renal proximal tubule followed by elimination via the urine is a major pathway in this detoxification process. Accordingly, a large number of organic anion transport proteins belonging to several different gene families have been identified and found to be expressed in the proximal nephron. The function of these transporters, in combination with the high volume of renal blood flow, predisposes the kidney to increased toxic susceptibility. Understanding how the kidney mediates the transport of organic anions is integral to achieving desired therapeutic outcomes in response to drug interactions and chemical exposures, to understanding the progression of some disease states, and to predicting the influence of genetic variation upon these processes. This review will focus on the organic anion transporter (OAT) family and discuss the known members, their mechanisms of action, subcellular localization, and current evidence implicating their function as a determinant of the toxicity of certain endogenous and xenobiotic agents.
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Affiliation(s)
- Douglas H Sweet
- Department of Pharmaceutical Sciences, Medical University of South Carolina, 280 Calhoun Street (Room QE218), PO Box 250140, Charleston, SC 29425, USA.
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1050
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Fonfría E, Vilaró MT, Babot Z, Rodríguez-Farré E, Suñol C. Mercury compounds disrupt neuronal glutamate transport in cultured mouse cerebellar granule cells. J Neurosci Res 2005; 79:545-53. [PMID: 15635608 DOI: 10.1002/jnr.20375] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cerebellar granule cells are targeted selectively by mercury compounds in vivo. Despite the affinity of mercury for thiol groups present in all cells, the molecular determinant(s) of selective cerebellar degeneration remain to be elucidated fully. We studied the effect of mercury compounds on neuronal glutamate transport in primary cultures of mouse cerebellar granule cells. Immunoblots probed with an antibody against the excitatory amino acid transporter (EAAT) neuronal glutamate transporter, EAAT3, revealed the presence of a specific band in control and mercury-treated cultures. Micromolar concentrations of both methylmercury and mercuric chloride increased the release of endogenous glutamate, inhibited glutamate uptake, reduced mitochondrial activity, and decreased ATP levels. All these effects were completely prevented by the nonpermeant reducing agent Tris-(2-carboxyethyl)phosphine (TCEP). Reduction of mitochondrial activity by mercuric chloride, but not by methylmercury, was inhibited significantly by 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS) and by reduced extracellular Cl- ion concentration. In addition, DIDS and low extracellular Cl- completely inhibited the release of glutamate induced by mercuric chloride, and produced a partial although significant reduction of that induced by methylmercury. We suggest that a direct inhibition of glutamate uptake triggers an imbalance in cell homeostasis, leading to neuronal failure and Cl(-)-regulated cellular glutamate efflux. Our results demonstrate that neuronal glutamate transport is a novel target to be taken into account when assessing mercury-induced neurotoxicity.
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Affiliation(s)
- Elena Fonfría
- Department of Neurochemistry, Institut d'Investigacions Biomèdiques de Barcelona, Consejo Superior de Investigaciones Científicas, CSIC-IDIBAPS, Barcelona, Spain
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