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Chien CY, Wang JD, Lin CC. Nerve excitability test and lead toxicity: a case-control study. J Occup Med Toxicol 2023; 18:19. [PMID: 37653420 PMCID: PMC10472560 DOI: 10.1186/s12995-023-00385-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 08/11/2023] [Indexed: 09/02/2023] Open
Abstract
BACKGROUND Although conventional electrophysiological parameters have been proposed as clinical indicators for monitoring lead neuropathies, their correlations with blood lead level are weak. In this study, we investigated the applicability of nerve excitability tests (NETs) to evaluate lead intoxication. METHODS Fourteen workers who were exposed to lead with an elevated blood level ranging from 17.8 to 64.9 µg/dL and 20 healthy controls with similar ages and body heights were enrolled. Both workers and controls underwent nerve conduction studies (NCSs), motor evoked potentials (MEPs) with transcranial magnetic stimulation (TMS), and NETs. RESULTS NCSs showed prolonged distal latencies and decreased motor nerve conduction velocity of median nerves in the workers but without significant correlation to blood lead level (BLL). Significantly prolonged MEP latency was observed in the workers (+ 6 ms). NETs demonstrated hyperpolarized resting membrane potentials in stimulus-response curves and changes in the property of potassium channels under a hyperpolarized current in threshold electrotonus, implying that lead hyperpolarized nerves by interfering with potassium channels. NETs also showed a better correlation with BLL than conventional electrophysiological parameters. CONCLUSIONS Axonal hyperpolarization and central conduction delay are more apparently reflecting elevated BLL than NCS. NET may have the potential for early detection of lead neuropathy.
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Affiliation(s)
- Chung-Yao Chien
- Department of Neurology, College of Medicine, National Cheng Kung University Hospital, National Cheng Kung University, 138 Sheng Li Road, Tainan, 704, Taiwan
| | - Jung-Der Wang
- Department of Public Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Department of Occupational and Environmental Medicine, National Cheng Kung University Hospital, Tainan, Taiwan
| | - Chou-Ching Lin
- Department of Neurology, College of Medicine, National Cheng Kung University Hospital, National Cheng Kung University, 138 Sheng Li Road, Tainan, 704, Taiwan.
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.
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Bazvand F, Mahdizad Z. Presumed retinal lead poisoning: a case report. Doc Ophthalmol 2022; 145:71-76. [PMID: 35691959 DOI: 10.1007/s10633-022-09878-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 05/08/2022] [Indexed: 11/25/2022]
Abstract
PURPOSE To describe a case of presumed retinal lead poisoning. METHODS Clinical examination, optical coherence tomography, fundus autofluorescence, fluorescein angiography, and electroretinography were used to study a 42-year-old male with the complaint of bilateral reduced vision following systemic lead poisoning. RESULTS The fundus examination showed venous tortuosity, as well as macular atrophy, and pigmentary changes in his both eyes. Optical coherence tomography revealed retinal thinning, outer retinal and retinal pigment epithelium atrophy, as well as foveal schitic changes. Blue autofluorescence showed moderately hypoautofluorescence in peripapillary area of both eyes. Fluorescein angiogram showed a leopard-like pattern of hypo- and hyperfluorescence in the posterior pole. Electroretinogram showed a moderate reduction in photopic and scotopic responses. CONCLUSIONS The most probable diagnosis of this case is early onset retinal lead poisoning.
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Affiliation(s)
- Fatemeh Bazvand
- Retina and Vitreous Service, Farabi Comprehensive Center of Excellence in Ophthalmology, Tehran University of Medical Sciences, Qazvin square, Tehran, 1336616351, Iran
| | - Zahra Mahdizad
- Retina and Vitreous Service, Farabi Comprehensive Center of Excellence in Ophthalmology, Tehran University of Medical Sciences, Qazvin square, Tehran, 1336616351, Iran.
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Fox DA. Retinal and visual system: occupational and environmental toxicology. HANDBOOK OF CLINICAL NEUROLOGY 2015; 131:325-40. [PMID: 26563796 DOI: 10.1016/b978-0-444-62627-1.00017-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Occupational chemical exposure often results in sensory systems alterations that occur without other clinical signs or symptoms. Approximately 3000 chemicals are toxic to the retina and central visual system. Their dysfunction can have immediate, long-term, and delayed effects on mental health, physical health, and performance and lead to increased occupational injuries. The aims of this chapter are fourfold. First, provide references on retinal/visual system structure, function, and assessment techniques. Second, discuss the retinal features that make it especially vulnerable to toxic chemicals. Third, review the clinical and corresponding experimental data regarding retinal/visual system deficits produced by occupational toxicants: organic solvents (carbon disulfide, trichloroethylene, tetrachloroethylene, styrene, toluene, and mixtures) and metals (inorganic lead, methyl mercury, and mercury vapor). Fourth, discuss occupational and environmental toxicants as risk factors for late-onset retinal diseases and degeneration. Overall, the toxicants altered color vision, rod- and/or cone-mediated electroretinograms, visual fields, spatial contrast sensitivity, and/or retinal thickness. The findings elucidate the importance of conducting multimodal noninvasive clinical, electrophysiologic, imaging and vision testing to monitor toxicant-exposed workers for possible retinal/visual system alterations. Finally, since the retina is a window into the brain, an increased awareness and understanding of retinal/visual system dysfunction should provide additional insight into acquired neurodegenerative disorders.
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Affiliation(s)
- Donald A Fox
- Departments of Vision Sciences, Biology and Biochemistry, Pharmacology, and Health and Human Performance, University of Houston, Houston, TX, USA.
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Alvarenga KDF, Alvarez Bernardez-Braga GR, Zucki F, Duarte JL, Lopes AC, Feniman MR. Correlation analysis of the long latency auditory evoked potential N2 and cognitive P3 with the level of lead poisoning in children. Int Arch Otorhinolaryngol 2013; 17:41-6. [PMID: 25991992 PMCID: PMC4423252 DOI: 10.7162/s1809-97772013000100007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 11/04/2012] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION The effects of lead on children's health have been widely studied. AIM To analyze the correlation between the long latency auditory evoked potential N2 and cognitive P3 with the level of lead poisoning in Brazilian children. METHODS This retrospective study evaluated 20 children ranging in age from 7 to 14 years at the time of audiological and electrophysiological evaluations. We performed periodic surveys of the lead concentration in the blood and basic audiological evaluations. Furthermore, we studied the auditory evoked potential long latency N2 and cognitive P3 by analyzing the absolute latency of the N2 and P3 potentials and the P3 amplitude recorded at Cz. At the time of audiological and electrophysiological evaluations, the average concentration of lead in the blood was less than 10 ug/dL. RESULTS In conventional audiologic evaluations, all children had hearing thresholds below 20 dBHL for the frequencies tested and normal tympanometry findings; the auditory evoked potential long latency N2 and cognitive P3 were present in 95% of children. No significant correlations were found between the blood lead concentration and latency (p = 0.821) or amplitude (p = 0.411) of the P3 potential. However, the latency of the N2 potential increased with the concentration of lead in the blood, with a significant correlation (p = 0.030). CONCLUSION Among Brazilian children with low lead exposure, a significant correlation was found between blood lead levels and the average latency of the auditory evoked potential long latency N2; however, a significant correlation was not observed for the amplitude and latency of the cognitive potential P3.
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Affiliation(s)
- Kátia de Freitas Alvarenga
- Speech Therapist; Associate Professor at the Department of Speech Therapy of the College of Dentistry of Bauru/University of São Paulo - FOB/USP, Bauru, São Paulo, Brazil
| | | | - Fernanda Zucki
- Speech Therapist; Master in Communication Disorders by the Universidade Tuiuti do Paraná - UTP/PR. PhD student in Applied Dental Sciences Program of Bauru Dental School/University of São Paulo FOB/USP, Bauru, São Paulo, Brazil
| | - Josilene Luciene Duarte
- Speech Therapist, Master in Speech Pathology, Bauru Dental School, University of São Paulo, Brazil. PhD student in Applied Dental Sciences Program of Bauru Dental School/University of São Paulo FOB/USP, Bauru, São Paulo, Brazil
| | - Andrea Cintra Lopes
- Speech Therapist; Professor, Doctor, at the Department of Speech Therapy of Bauru Dental School/University of São Paulo FOB/USP, Bauru, São Paulo, Brazil
| | - Mariza Ribeiro Feniman
- Speech Therapist; Full Professor for the Speech Therapy Course, Bauru Dental School/University of São Paulo FOB/ USP, Bauru, São Paulo, Brazil
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Boucher O, Muckle G, Saint-Amour D, Dewailly E, Ayotte P, Jacobson SW, Jacobson JL, Bastien CH. The relation of lead neurotoxicity to the event-related potential P3b component in Inuit children from arctic Québec. Neurotoxicology 2009; 30:1070-7. [PMID: 19576242 DOI: 10.1016/j.neuro.2009.06.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 06/05/2009] [Accepted: 06/19/2009] [Indexed: 11/30/2022]
Abstract
The event-related potential (ERP) P3b, a cognitive electrophysiological measure that has been linked to working memory processing in many experimental paradigms, was measured in Inuit children from Nunavik (Arctic Québec, Canada) to assess lead (Pb) neurotoxicity. Visual and auditory oddball paradigms were administered at 5 (N=27) and 11 (N=110) years of age, respectively, to elicit this ERP component. Pearson correlations and multiple regression analyses were performed to examine the associations between Pb levels and P3b parameters (peak latency and amplitude). Greater prenatal Pb exposure was related to a decrease in P3b amplitude at 5 years of age, and early childhood Pb exposure was associated with delayed P3b latency at 5 years. No significant association was observed at 11 years. These results, in line with those from previous neurobehavioral studies, suggest that Pb exposure affects cognitive processing in children even though the Pb levels measured in a large majority of our sample were below the threshold value for public health intervention used by federal agencies. This study strengthens the arguments for reducing sources of Pb exposure in Nunavik and for lowering the blood Pb concentrations considered "acceptable" in governmental policies.
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Murata K, Iwata T, Dakeishi M, Karita K. Lead Toxicity: Does the Critical Level of Lead Resulting in Adverse Effects Differ between Adults and Children? J Occup Health 2009; 51:1-12. [DOI: 10.1539/joh.k8003] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Katsuyuki Murata
- Department of Environmental Health SciencesAkita University School of MedicineJapan
| | - Toyoto Iwata
- Department of Environmental Health SciencesAkita University School of MedicineJapan
| | - Miwako Dakeishi
- Department of Environmental Health SciencesAkita University School of MedicineJapan
| | - Kanae Karita
- Department of Public HealthKyorin University School of MedicineJapan
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Visually-evoked P300 and NOGO potentials as indicators of central nervous system function in patients with vibration syndrome. Int Arch Occup Environ Health 2008; 82:79-85. [DOI: 10.1007/s00420-008-0309-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Accepted: 02/20/2008] [Indexed: 10/22/2022]
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Borges VC, Santos FW, Rocha JBT, Nogueira CW. Heavy metals modulate glutamatergic system in human platelets. Neurochem Res 2007; 32:953-8. [PMID: 17406985 DOI: 10.1007/s11064-006-9231-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Accepted: 11/16/2006] [Indexed: 11/30/2022]
Abstract
Research strategies have been developed to characterize parameters in peripheral tissues that might easily be measured in humans as surrogate markers of damage, dysfunction or interactions involving neural targets of toxicants. The similarities between platelet and neuron may even be clinically important, as a number of biochemical markers show parallel changes in the central nervous system (CNS) and platelets. The purpose of our research was to investigate the effect of Hg(2+), Pb(2+) and Cd(2+) on the [(3)H]-glutamate binding and [(3)H]-glutamate uptake in human platelets. The involvement of oxidative stress in the modulation of glutamatergic system induced by heavy metals was also investigated. The present study clearly demonstrates that Hg(2+), Cd(2+), and Pb(2+) inhibited [(3)H]-glutamate uptake in human platelets. Hg(2+) inhibited [(3)H]-glutamate binding, while Cd(2+) and Pb(2+) stimulated [(3)H]-glutamate binding in human platelets. Hg(2+), Cd(2+) and Pb(2+) increased lipid peroxidation levels and reactive oxygen species (ROS) measurement in platelets. The present limited results could suggest that glutamatergic system may be used as a potential biomarker for neurotoxic action of heavy metals in humans.
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Affiliation(s)
- V C Borges
- Departamento de Química, Centro de Ciencias Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
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Hirata M, Taoda K, Kitahara T, Tsujimura H, Nishiyama K. Neuro-physiological study in persons with cervico-brachial disorders. INDUSTRIAL HEALTH 2005; 43:630-5. [PMID: 16294917 DOI: 10.2486/indhealth.43.630] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
OBJECTIVES In order to clarify the involvement in the nervous system by cervico-brachial disorders (CBD), we performed neurophysiological tests on the peripheral nervous system (PNS) and the central nervous system (CNS) in patients with CBD, subclinicals and healthy controls. SUBJECTS AND METHODS We employed antidromic sensory nerve conduction velocities (SCV) in the hands and fingers for PNS function and event-related potentials (P300) for CNS higher function. Subjects for SCV were 27 patients, 14 workers with sign and symptoms of CBD (subclinicals) and 22 controls. Subjects for P300 were 23 patients, 12 subclinicals and 10 healthy controls. CONCLUSIONS In the PNS, since significant reduction SCV in the index finger among patients was observed, we could not find clear evidence of decrease of conduction function. In the CNS, since the latencies and amplitudes of auditory P300 among patients were significantly delayed and decreased, respectively, and the latencies significantly correlated with symptom score, it was suggested that the dysfunction of the cognition and memory function. However, further investigation is necessary to clarify the mechanism.
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Affiliation(s)
- Mamoru Hirata
- Department of Hazard Assessment, National Institute of Industrial Health, Nagao 6-21-1, Tama-ku, Kawasaki 214-8585, Japan
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Struzyńska L, Chalimoniuk M, Sulkowski G. Changes in expression of neuronal and glial glutamate transporters in lead-exposed adult rat brain. Neurochem Int 2005; 47:326-33. [PMID: 15985313 DOI: 10.1016/j.neuint.2005.05.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2005] [Revised: 05/12/2005] [Accepted: 05/12/2005] [Indexed: 11/24/2022]
Abstract
Excitatory amino acid transporters (EAATs) are membrane-bound proteins localized in glial and neuronal cells which transport glutamate (Glu) in a process essential for terminating its action and protecting neurons from excitotoxic damage. Since Pb-induced neurotoxicity has a glutamatergic component and astrocytes serve as a cellular Pb deposition site, it was of interest to investigate the response of main glutamate transporters to short-term lead exposure in the adult rat brain (25mg/kg b.w. of lead acetate, i.p. for 3 days). We examined the expression of mRNA and protein of GLAST, GLT-1 and EAAC1 in homogenates obtained from cerebellum, hippocampus and forebrain. Molecular evidence is provided which indicates that, of the two glial transporters, GLT-1 is more susceptible than GLAST to the neurotoxic effect arising from Pb. RT-PCR analysis revealed highly decreased expression of GLT-1 mRNA in forebrain and hippocampus. In contrast, GLAST was overexpressed in forebrain and in cerebellum. In the case of EAAC1, the enhanced expression of mRNA and protein of transporter was observed only in forebrain. The results demonstrate regional differences in the expression of glutamate transporters after short-term exposure to Pb. In forebrain, downregulation of GLT-1 is compensated by enhanced expression of GLAST, while in hippocampus, the expression of both is lowered. This observation suggests that under conditions of Pb toxicity in adult rat brain, the hippocampus is most vulnerable to the excitotoxic cell damage arising from impaired clearance of the released glutamate.
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Affiliation(s)
- Lidia Struzyńska
- Laboratory of Pathoneurochemistry, Department of Neurochemistry, Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland.
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