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Almeida-Silva J, Menezes DS, Fernandes JMP, Almeida MC, Vasco-Dos-Santos DR, Saraiva RM, Viçosa AL, Perez SAC, Andrade SG, Suarez-Fontes AM, Vannier-Santos MA. The repositioned drugs disulfiram/diethyldithiocarbamate combined to benznidazole: Searching for Chagas disease selective therapy, preventing toxicity and drug resistance. Front Cell Infect Microbiol 2022; 12:926699. [PMID: 35967878 PMCID: PMC9372510 DOI: 10.3389/fcimb.2022.926699] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 06/27/2022] [Indexed: 12/20/2022] Open
Abstract
Chagas disease (CD) affects at least 6 million people in 21 South American countries besides several thousand in other nations all over the world. It is estimated that at least 14,000 people die every year of CD. Since vaccines are not available, chemotherapy remains of pivotal relevance. About 30% of the treated patients cannot complete the therapy because of severe adverse reactions. Thus, the search for novel drugs is required. Here we tested the benznidazole (BZ) combination with the repositioned drug disulfiram (DSF) and its derivative diethyldithiocarbamate (DETC) upon Trypanosoma cruzi in vitro and in vivo. DETC-BZ combination was synergistic diminishing epimastigote proliferation and enhancing selective indexes up to over 10-fold. DETC was effective upon amastigotes of the BZ- partially resistant Y and the BZ-resistant Colombiana strains. The combination reduced proliferation even using low concentrations (e.g., 2.5 µM). Scanning electron microscopy revealed membrane discontinuities and cell body volume reduction. Transmission electron microscopy revealed remarkable enlargement of endoplasmic reticulum cisternae besides, dilated mitochondria with decreased electron density and disorganized kinetoplast DNA. At advanced stages, the cytoplasm vacuolation apparently impaired compartmentation. The fluorescent probe H2-DCFDA indicates the increased production of reactive oxygen species associated with enhanced lipid peroxidation in parasites incubated with DETC. The biochemical measurement indicates the downmodulation of thiol expression. DETC inhibited superoxide dismutase activity on parasites was more pronounced than in infected mice. In order to approach the DETC effects on intracellular infection, peritoneal macrophages were infected with Colombiana trypomastigotes. DETC addition diminished parasite numbers and the DETC-BZ combination was effective, despite the low concentrations used. In the murine infection, the combination significantly enhanced animal survival, decreasing parasitemia over BZ. Histopathology revealed that low doses of BZ-treated animals presented myocardial amastigote, not observed in combination-treated animals. The picrosirius collagen staining showed reduced myocardial fibrosis. Aminotransferase de aspartate, Aminotransferase de alanine, Creatine kinase, and urea plasma levels demonstrated that the combination was non-toxic. As DSF and DETC can reduce the toxicity of other drugs and resistance phenotypes, such a combination may be safe and effective.
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Affiliation(s)
- Juliana Almeida-Silva
- Innovations in Therapies, Education and Bioproducts Laboratory, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brazil
| | - Diego Silva Menezes
- Parasite Biology Laboratory, Gonçalo Moniz Institute, Oswaldo Cruz Foundation, Salvador, BA, Brazil
| | - Juan Mateus Pereira Fernandes
- Innovations in Therapies, Education and Bioproducts Laboratory, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brazil
| | - Márcio Cerqueira Almeida
- Parasite Biology Laboratory, Gonçalo Moniz Institute, Oswaldo Cruz Foundation, Salvador, BA, Brazil
| | - Deyvison Rhuan Vasco-Dos-Santos
- Innovations in Therapies, Education and Bioproducts Laboratory, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brazil
| | - Roberto Magalhães Saraiva
- Laboratory of Clinical Research on Chagas Disease, Evandro Chagas Infectious Disease Institute, Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brazil
| | - Alessandra Lifsitch Viçosa
- Experimental Pharmacotechnics Laboratory, Department of Galenic Innovation, Institute of Drug Technology - Farmanguinhos, Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brazil
| | - Sandra Aurora Chavez Perez
- Project Management Technical Assistance, Institute of Drug Technology - Farmanguinhos, Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brazil
| | - Sônia Gumes Andrade
- Experimental Chagas Disease Laboratory, Gonçalo Moniz Institute, Oswaldo Cruz Foundation, Salvador, BA, Brazil
| | - Ana Márcia Suarez-Fontes
- Innovations in Therapies, Education and Bioproducts Laboratory, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brazil
| | - Marcos André Vannier-Santos
- Innovations in Therapies, Education and Bioproducts Laboratory, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brazil
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Abstract
Toxic peripheral neuropathies are an important form of acquired polyneuropathy produced by a variety of xenobiotics and different exposure scenarios. Delineating the mechanisms of neurotoxicants and determining the degenerative biological pathways triggered by peripheral neurotoxicants will facilitate the development of sensitive and specific biochemical-based methods for identifying neurotoxicants, designing therapeutic interventions, and developing structure-activity relationships for predicting potential neurotoxicants. This review presents an overview of the general concepts of toxic peripheral neuropathies with the goal of providing insight into why certain agents target the peripheral nervous system and produce their associated lesions. Experimental data and the main hypotheses for the mechanisms of selected agents that produce neuronopathies, axonopathies, or myelinopathies including covalent or noncovalent modifications, compromised energy or protein biosynthesis, and oxidative injury and disruption of ionic gradients across membranes are presented. The relevance of signaling between the main components of peripheral nerve, that is, glia, neuronal perikaryon, and axon, as a target for neurotoxicants and the contribution of active programmed degenerative pathways to the lesions observed in toxic peripheral neuropathies is also discussed.
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Zhang Q, Li Q, Ma J, Zhao Y. PM2.5 impairs neurobehavior by oxidative stress and myelin sheaths injury of brain in the rat. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 242:994-1001. [PMID: 30373045 DOI: 10.1016/j.envpol.2018.07.031] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 06/22/2018] [Accepted: 07/09/2018] [Indexed: 06/08/2023]
Abstract
Air particulate matter (PM) is a serious environmental problem that has been found to cause neuropathological disorders. Although the general toxicity of PM2.5 has been intensively studied, its neurobehavior effects are poorly discussed. In this study, we aim to investigate whether different exposure time of PM2.5 influence neurobehavior of rats, induce oxidative stress, histopathologic abnormalities, apoptosis, or changes of mitochondria and myelin. The results reveal that exposure to PM2.5 impaired spatial learning and memory, inquiring ability, as well as sensory function. These alterations were related to ultrastructure changes of mitochondria and myelin sheaths, abnormal expression of apoptosis-related proteins (Caspase-3, Caspase-9). These results provide a basis for a better understanding of myelin abnormality-related neurobehavior impairment in response to PM2.5.
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Affiliation(s)
- Qun Zhang
- School of Ecological and Environmental Sciences, Shanghai Key Laboratory for Urban Ecological Process and Eco-Restoration, East China Normal University, Shanghai, 200241, China; Institute of Eco-Chongming, Shanghai, 200062, China
| | - Qingzhao Li
- School of Public Health, North China University of Science and Technology, Tangshan, Hebei, 063000, PR China
| | - Jincai Ma
- School of Environment and Resources, Ji Lin University, Ji Lin, 130021, PR China.
| | - Yaping Zhao
- School of Ecological and Environmental Sciences, Shanghai Key Laboratory for Urban Ecological Process and Eco-Restoration, East China Normal University, Shanghai, 200241, China; Institute of Eco-Chongming, Shanghai, 200062, China.
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4
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Pan H, Ding Y, Yan N, Nie Y, Li M, Tong L. Trehalose prevents sciatic nerve damage to and apoptosis of Schwann cells of streptozotocin-induced diabetic C57BL/6J mice. Biomed Pharmacother 2018; 105:907-914. [DOI: 10.1016/j.biopha.2018.06.069] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 06/08/2018] [Accepted: 06/13/2018] [Indexed: 02/06/2023] Open
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Influence of a low dose of silver nanoparticles on cerebral myelin and behavior of adult rats. Toxicology 2016; 363-364:29-36. [PMID: 27427492 DOI: 10.1016/j.tox.2016.07.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 07/11/2016] [Accepted: 07/13/2016] [Indexed: 11/23/2022]
Abstract
Nanoscale particles have large surface to volume ratio that significantly enhances their chemical and biological reactivity. Although general toxicity of nano silver (nanoAg) has been intensively studied in both in vitro and in vivo models, its neurotoxic effects are poorly known, especially those of low-dose exposure. In the present study we assess whether oral administration of nanoAg influences behavior of exposed rats and induces changes in cerebral myelin. We examine the effect of prolonged exposure of adult rats to small (10nm) citrate-stabilized nanoAg particles at a low dose of 0.2mg/kg b.w. (as opposed to the ionic silver) in a comprehensive behavioral analysis. Myelin ultrastructure and the expression of myelin-specific proteins are also investigated. The present study reveals slight differences with respect to behavioral effects of Ag(+)- but not nanoAg-treated rats. A weak depressive effect and hyperalgesia were observed after Ag(+) exposure whereas administration of nanoAg was found to specifically increase body weight and body temperature of animals. Both nanoAg and Ag(+) induce morphological disturbances in myelin sheaths and alter the expression of myelin-specific proteins CNP, MAG and MOG. These results suggest that the CNS may be a target of low-level toxicity of nanoAg.
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Schlebach JP, Narayan M, Alford C, Mittendorf KF, Carter BD, Li J, Sanders CR. Conformational Stability and Pathogenic Misfolding of the Integral Membrane Protein PMP22. J Am Chem Soc 2015; 137:8758-68. [PMID: 26102530 PMCID: PMC4507940 DOI: 10.1021/jacs.5b03743] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
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Despite broad biochemical
relevance, our understanding of the physiochemical
reactions that limit the assembly and cellular trafficking of integral
membrane proteins remains superficial. In this work, we report the
first experimental assessment of the relationship between the conformational
stability of a eukaryotic membrane protein and the degree to which
it is retained by cellular quality control in the secretory pathway.
We quantitatively assessed both the conformational equilibrium and
cellular trafficking of 12 variants of the α-helical membrane
protein peripheral myelin protein 22 (PMP22), the intracellular misfolding
of which is known to cause peripheral neuropathies associated with
Charcot–Marie–Tooth disease (CMT). We show that the
extent to which these mutations influence the energetics of Zn(II)-mediated
PMP22 folding is proportional to the observed reduction in cellular
trafficking efficiency. Strikingly, quantitative analyses also reveal
that the reduction of motor nerve conduction velocities in affected
patients is proportional to the extent of the mutagenic destabilization.
This finding provides compelling evidence that the effects of these
mutations on the energetics of PMP22 folding lie at the heart of the
molecular basis of CMT. These findings highlight conformational stability
as a key factor governing membrane protein biogenesis and suggest
novel therapeutic strategies for CMT.
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Affiliation(s)
| | | | - Catherine Alford
- #Flow Cytometry Core, Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee 37232, United States
| | | | | | - Jun Li
- ⊥Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee 37232, United States
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Frid K, Einstein O, Friedman-Levi Y, Binyamin O, Ben-Hur T, Gabizon R. Aggregation of MBP in chronic demyelination. Ann Clin Transl Neurol 2015; 2:711-21. [PMID: 26273684 PMCID: PMC4531054 DOI: 10.1002/acn3.207] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 03/26/2015] [Indexed: 12/14/2022] Open
Abstract
Objectives Misfolding of key disease proteins to an insoluble state is associated with most neurodegenerative conditions, such as prion, Parkinson, and Alzheimer’s diseases. In this work, and by studying animal models of multiple sclerosis, we asked whether this is also the case for myelin basic protein (MBP) in the late and neurodegenerative phases of demyelinating diseases. Methods To this effect, we tested whether MBP, an essential myelin component, present prion-like properties in animal models of MS, as is the case for Cuprizone-induced chronic demyelination or chronic phases of Experimental Autoimmune Encephalomyelitis (EAE). Results We show here that while total levels of MBP were not reduced following extensive demyelination, part of these molecules accumulated thereafter as aggregates inside oligodendrocytes or around neuronal cells. In chronic EAE, MBP precipitated concomitantly with Tau, a marker of diverse neurodegenerative conditions, including MS. Most important, analysis of fractions from Triton X-100 floatation gradients suggest that the lipid composition of brain membranes in chronic EAE differs significantly from that of naïve mice, an effect which may relate to oxidative insults and subsequently prevent the appropriate insertion and compaction of new MBP in the myelin sheath, thereby causing its misfolding and aggregation. Interpretation Prion-like aggregation of MBP following chronic demyelination may result from an aberrant lipid composition accompanying this pathological status. Such aggregation of MBP may contribute to neuronal damage that occurs in the progressive phase of MS.
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Affiliation(s)
- Kati Frid
- Department of Neurology, The Agnes Ginges Center for Human Neurogenetics, Hadassah University Hospital Jerusalem, 91120, Israel
| | - Ofira Einstein
- Department of Neurology, The Agnes Ginges Center for Human Neurogenetics, Hadassah University Hospital Jerusalem, 91120, Israel
| | - Yael Friedman-Levi
- Department of Neurology, The Agnes Ginges Center for Human Neurogenetics, Hadassah University Hospital Jerusalem, 91120, Israel
| | - Orli Binyamin
- Department of Neurology, The Agnes Ginges Center for Human Neurogenetics, Hadassah University Hospital Jerusalem, 91120, Israel
| | - Tamir Ben-Hur
- Department of Neurology, The Agnes Ginges Center for Human Neurogenetics, Hadassah University Hospital Jerusalem, 91120, Israel
| | - Ruth Gabizon
- Department of Neurology, The Agnes Ginges Center for Human Neurogenetics, Hadassah University Hospital Jerusalem, 91120, Israel
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8
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Dennis KE, Valentine WM. Ziram and sodium N,N-dimethyldithiocarbamate inhibit ubiquitin activation through intracellular metal transport and increased oxidative stress in HEK293 cells. Chem Res Toxicol 2015; 28:682-90. [PMID: 25714994 PMCID: PMC4406076 DOI: 10.1021/tx500450x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
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Ubiquitin activating enzyme E1 plays
a pivotal role in ubiquitin
based protein signaling through regulating the initiating step of
the cascade. Previous studies demonstrated that E1 is inhibited by
covalent modification of reactive cysteines contained within the ubiquitin-binding
groove and by conditions that increase oxidative stress and deplete
cellular antioxidants. In this study, we determined the relative contribution
of covalent adduction and oxidative stress to E1 inhibition produced
by ziram and sodium N,N-dimethyldithiocarbamate
(DMDC) in HEK293 cells. Although no dithiocarbamate-derived E1 adducts
were identified on E1 using shotgun LC/MS/MS for either ziram or DMDC,
both dithiocarbamates significantly decreased E1 activity, with ziram
demonstrating greater potency. Ziram increased intracellular levels
of zinc and copper, DMDC increased intracellular levels of only copper,
and both dithiocarbamates enhanced oxidative injury evidenced by elevated
levels of protein carbonyls and expression of heme oxygenase-1. To
assess the contribution of intracellular copper transport to E1 inhibition,
coincubations were performed with the copper chelator triethylenetetramine
hydrochloride (TET). TET significantly protected E1 activity for both
of the dithiocarbamates and decreased the associated oxidative injury
in HEK293 cells as well as prevented dithiocarbamate-mediated lipid
peroxidation assayed using an ethyl aracidonate micelle system. Because
TET did not completely ameliorate intracellular transport of copper
or zinc for ziram, TET apparently maintained E1 activity through its
ability to diminish dithiocarbamate-mediated oxidative stress. Experiments
to determine the relative contribution of elevated intracellular zinc
and copper were performed using a metal free incubation system and
showed that increases in either metal were sufficient to inhibit E1.
To evaluate the utility of the HEK293 in vitro system for screening
environmental agents, a series of additional pesticides and metals
was assayed, and eight agents that produced a significant decrease
and five that produced a significant increase in activated E1 were
identified. These studies suggest that E1 is a sensitive redox sensor
that can be modulated by exposure to environmental agents and can
regulate downstream cellular processes.
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Affiliation(s)
- Kathleen E Dennis
- †Department of Pathology, Microbiology and Immunology, ‡Center in Molecular Toxicology, §Vanderbilt Brain Institute, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, Tennessee 37232-2561, United States
| | - William M Valentine
- †Department of Pathology, Microbiology and Immunology, ‡Center in Molecular Toxicology, §Vanderbilt Brain Institute, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, Tennessee 37232-2561, United States
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9
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Caito SW, Valentine WM, Aschner M. Dopaminergic neurotoxicity of S-ethyl N,N-dipropylthiocarbamate (EPTC), molinate, and S-methyl-N,N-diethylthiocarbamate (MeDETC) in Caenorhabditis elegans. J Neurochem 2013; 127:837-51. [PMID: 23786526 DOI: 10.1111/jnc.12349] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 06/14/2013] [Accepted: 06/17/2013] [Indexed: 12/14/2022]
Abstract
Epidemiological studies corroborate a correlation between pesticide use and Parkinson's disease (PD). Thiocarbamate and dithiocarbamate pesticides are widely used and produce neurotoxicity in the peripheral nervous system. Recent evidence from rodent studies suggests that these compounds also cause dopaminergic (DAergic) dysfunction and altered protein processing, two hallmarks of PD. However, DAergic neurotoxicity has yet to be documented. We assessed DAergic dysfunction in Caenorhabditis elegans (C. elegans) to investigate the ability of thiocarbamate pesticides to induce DAergic neurodegeneration. Acute treatment with either S-ethyl N,N-dipropylthiocarbamate (EPTC), molinate, or a common reactive intermediate of dithiocarbamate and thiocarbamate metabolism, S-methyl-N,N-diethylthiocarbamate (MeDETC), to gradual loss of DAergic cell morphology and structure over the course of 6 days in worms expressing green fluorescent protein (GFP) under a DAergic cell specific promoter. HPLC analysis revealed decreased DA content in the worms immediately following exposure to MeDETC, EPTC, and molinate. In addition, worms treated with the three test compounds showed a drastic loss of DAergic-dependent behavior over a time course similar to changes in DAergic cell morphology. Alterations in the DAergic system were specific, as loss of cell structure and neurotransmitter content was not observed in cholinergic, glutamatergic, or GABAergic systems. Overall, our data suggest that thiocarbamate pesticides promote neurodegeneration and DAergic cell dysfunction in C. elegans, and may be an environmental risk factor for PD.
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Affiliation(s)
- Samuel W Caito
- Division of Clinical Pharmacology and Pediatric Toxicology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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Synthesis, biological evaluation, and molecular docking studies of benzyl, alkyl and glycosyl [2-(arylamino)-4,4-dimethyl-6-oxo-cyclohex-1-ene]carbodithioates, as potential immunomodulatory and immunosuppressive agents. Bioorg Med Chem 2012; 20:3000-8. [DOI: 10.1016/j.bmc.2012.03.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 02/28/2012] [Accepted: 03/01/2012] [Indexed: 01/06/2023]
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11
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The significance of copper chelators in clinical and experimental application. J Nutr Biochem 2011; 22:301-10. [DOI: 10.1016/j.jnutbio.2010.06.010] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2010] [Revised: 06/08/2010] [Accepted: 06/30/2010] [Indexed: 01/17/2023]
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12
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Synthesis and X-ray analysis of butyl and glycosyl (2-arylamino-4,4-dimethyl-6-oxocyclohex-1-ene)carbodithioates and their possible cyclization to 2-thioxo-6,7-dihydro-1H-benzo[d][1,3]thiazin-5(2H)-one derivatives. Carbohydr Res 2011; 346:169-76. [PMID: 21163469 DOI: 10.1016/j.carres.2010.11.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 11/02/2010] [Accepted: 11/04/2010] [Indexed: 12/30/2022]
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13
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Valentine HL, Viquez OM, Valentine WM. Peripheral nerve and brain differ in their capacity to resolve N,N-diethyldithiocarbamate-mediated elevations in copper and oxidative injury. Toxicology 2010; 274:10-7. [PMID: 20452388 DOI: 10.1016/j.tox.2010.04.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 04/28/2010] [Accepted: 04/30/2010] [Indexed: 11/24/2022]
Abstract
Previous studies have demonstrated that N,N-diethyldithiocarbamate (DEDC) elevates copper and promotes oxidative stress within the nervous system. However, whether these effects resolve following cessation of exposure or have the potential to persist and result in cumulative injury has not been determined. In this study, an established model for DEDC myelin injury in the rat was used to determine whether copper levels, oxidative stress, and neuromuscular deficits resolve following the cessation of DEDC exposure. Rats were exposed to DEDC for 8 weeks and then either euthanized or maintained for 2, 6 or 12 weeks after cessation of exposure. At each time point copper levels were measured by inductively coupled mass spectrometry to assess the ability of sciatic nerve, brain, spinal cord and liver to eliminate excess copper post-exposure. The protein expression levels of glutathione transferase alpha, heme oxygenase 1 and superoxide dismutase 1 in peripheral nerve and brain were also determined by western blot to assess levels of oxidative stress as a function of post-exposure duration. As an initial assessment of the bioavailability of the excess copper in brain the protein expression levels of copper chaperone for superoxide dismutase 1, and prion protein were determined by western blot as a function of exposure and post-exposure duration. Neuromuscular function in peripheral nerve was evaluated using grip strengths, nerve conduction velocities, and morphologic changes at the light microscope level. The data demonstrated that in peripheral nerve, copper levels and oxidative stress return to control levels within several weeks after cessation of exposure. Neuromuscular function also showed a trend towards pre-exposure values, although the resolution of myelin lesions was more delayed. In contrast, total copper and antioxidant enzyme levels remained significantly elevated in brain for longer post-exposure periods. The persistence of effects observed in brain suggests that the central nervous system is more susceptible to long-term cumulative adverse effects from dithiocarbamates. Additionally, significant changes in expression levels of chaperone for superoxide dismutase 1, and prion protein were observed consistent with at least a portion of the excess copper being bioactive.
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Affiliation(s)
- Holly L Valentine
- Department of Pathology, Vanderbilt University Medical Center, 1161 21st Ave. S., Nashville, TN 37232-2561, USA
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Goldschmidt J, Wanger T, Engelhorn A, Friedrich H, Happel M, Ilango A, Engelmann M, Stuermer IW, Ohl FW, Scheich H. High-resolution mapping of neuronal activity using the lipophilic thallium chelate complex TlDDC: protocol and validation of the method. Neuroimage 2009; 49:303-15. [PMID: 19682585 DOI: 10.1016/j.neuroimage.2009.08.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 07/28/2009] [Accepted: 08/05/2009] [Indexed: 10/20/2022] Open
Abstract
In neurons the rate of K(+)-uptake increases with increasing activity. K(+)-analogues like the heavy metal ion thallium (Tl(+)) can be used, therefore, as tracers for imaging neuronal activity. However, when water-soluble Tl(+)-salts are injected systemically only minute amounts of the tracer enter the brain and the Tl(+)-uptake patterns are influenced by regional differences in blood-brain barrier (BBB) K(+)-permeability. We here show that the BBB-related limitations in using Tl(+) for imaging neuronal activity are no longer present when the lipophilic Tl(+) chelate complex thallium diethyldithiocarbamate (TlDDC) is applied. We systemically injected rodents with TlDDC and mapped the Tl(+)-distribution in the brain using an autometallographic (AMG) technique, a histochemical method for detecting heavy metals. We find that Tl(+)-doses for optimum AMG staining could be substantially reduced, and regional differences attributable to differences in BBB K(+)-permeability were no longer detectable, indicating that TlDDC crosses the BBB. At the cellular level, however, the Tl(+)-distribution was essentially the same as after injection of water-soluble Tl(+)-salts, indicating Tl(+)-release from TlDDC prior to neuronal or glial uptake. Upon sensory stimulation or intracortical microstimulation neuronal Tl(+)-uptake increased after TlDDC injection, upon muscimol treatment neuronal Tl(+)-uptake decreased. We present a protocol for mapping neuronal activity with cellular resolution, which is based on intravenous TlDDC injections during ongoing activity in unrestrained behaving animals and short stimulation times of 5 min.
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Affiliation(s)
- Jürgen Goldschmidt
- Leibniz Institut für Neurobiologie, Abteilung Akustik LernenSprache, Brenneckestrasse 6, Magdeburg, Germany.
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