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Smith DR, Woolard D, Luck ML, Laughlin NK. Succimer and the reduction of tissue lead in juvenile monkeys. Toxicol Appl Pharmacol 2000; 166:230-40. [PMID: 10906287 DOI: 10.1006/taap.2000.8973] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The extent to which succimer (2,3-dimercaptosuccinic acid, DMSA) chelation reduces target organ lead (Pb) levels, including the skeleton, relative to the cessation of Pb exposure is a primary consideration in evaluating its efficacy for reducing toxicity in children. Here, we utilized a rhesus monkey model of childhood Pb exposure and a sensitive stable (204)Pb isotope tracer methodology to determine the efficacy of succimer for reducing Pb in blood, liver, and skeletal tissues from chronic (>/=1 year) versus short-term (3-4 days) Pb exposures. Specific attention was paid to the efficacy of succimer treatment compared to the cessation of Pb exposure. Infant rhesus monkeys (n = 48) were exposed to Pb daily for 1 year or >1 year postpartum to reach and maintain a target blood Pb level of 35-40 microg/dL. Two successive 19-day succimer treatment regimens were administered at 53 and 65 weeks of age (30 mg/kg/day x 5 days followed by 20 mg/kg/day x 14 days). Blood was collected over the course of treatment, and liver and bone biopsy samples were collected on days 0, 5, and 20, relative to the start of treatment (day 0). Complete 24-h urine collections were conducted over the course of treatment. Results of the first chelation indicate that a single regimen of succimer treatment led to significant reductions in blood and liver Pb levels, relative to the placebo group. However, the cessation of Pb exposure alone (i.e., placebo) also led to significant reductions in blood and liver compared to pretreatment levels. Neither succimer nor the cessation of Pb exposure had a significant impact on bone lead levels. Blood Pb levels in the succimer-treated group rebounded within 5 days after treatment ended, becoming comparable with levels in the placebo group from that point on. Results from the second chelation indicate that succimer treatment is essentially equally efficacious in reducing blood Pb at moderate (20 microg/dL) levels where exposures ended >3 months previously and more elevated (40-50 microg/dL) levels where exposures ended just prior to treatment, relative to the placebo treatment. Finally, similar overall outcomes were observed for tissue Pb from recent exposures (i.e., (204)Pb tracer levels), indicating little or no apparent difference in the chelation of Pb from recent (3-4 days) versus long-term exposures. These data demonstrate that succimer does not reduce skeletal Pb levels, and they show that the efficacy of succimer for reducing blood Pb levels does not persist beyond the completion of treatment due to posttreatment rebounds in blood Pb from endogenous sources. They also demonstrate the relative benefit of eliminating Pb exposures, which serves to underscore the importance of primary prevention of Pb exposure. The extent to which these data reflect the efficacy of succimer for reducing neurocognitive impairment is not yet known, although those data are forthcoming.
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Rael LT, Ayala-Fierro F, Carter DE. The effects of sulfur, thiol, and thiol inhibitor compounds on arsine-induced toxicity in the human erythrocyte membrane. Toxicol Sci 2000; 55:468-77. [PMID: 10828280 DOI: 10.1093/toxsci/55.2.468] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The mechanism of arsine (AsH(3)) toxicity is not completely understood. The first cytotoxic effect of AsH(3) is disruption of ion homeostasis, with a subsequent hemolytic action. The only accepted treatment for AsH(3) toxicity is exchange transfusion of the blood. In this study the effect of sulfur, sulfur compounds, thiol-containing compounds, and thiol inhibitors on AsH(3)-induced disruption of membrane transport and hemolysis in human erythrocytes was investigated in vitro. Elemental sulfur, sodium thiosulfate, 5, 5'-dithio-bis(2-nitrobenzoic acid), and meso-2,3-dimercaptosuccinic acid were successful in delaying hemolysis, but the most successful agent was the sulfhydryl inhibitor, N-ethylmaleimide (NEM). This indicated that sulfhydryl groups, possibly membrane sulfhydryls, are major factors in the hemolytic mechanism of AsH(3). Measuring intracellular ion concentrations tested the effect of NEM on AsH(3)-induced disruption of membrane transport. AsH(3) alone caused all ions tested to flow with their concentration gradients: Intracellular K+ and Mg++ decreased, whereas Na+, Cl-, and Ca++ increased. NEM was unable to prevent ion loss except for Ca++, whose increase was prevented for 1 h after AsH(3) treatment. The influx of Ca++ in AsH(3)-treated erythrocytes is an irreversible event leading to hemolysis. Reduction of oxygenated hemoglobin to carboxyhemoglobin completely inhibited AsH(3)-induced hemolysis. In addition, AsH(3) and NEM had no direct chemical interactions. We concluded that membrane sulfhydryl groups are likely targets of AsH(3) toxicity, with NEM being able to prevent AsH(3)-induced hemolysis.
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Merkord J, Weber H, Kröning G, Hennighausen G. Antidotal effects of 2,3-dimercaptopropane-1-sulfonic acid (DMPS) and meso-2,3-dimercaptosuccinic acid (DMSA) on the organotoxicity of dibutyltin dichloride (DBTC) in rats. Hum Exp Toxicol 2000; 19:132-7. [PMID: 10773844 DOI: 10.1191/096032700678815701] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
1. Dialkyltin compounds have been widely used in industry and agriculture, mainly as biocides, catalysts and plast stabilizer. In dependence on the length of the alkyl chains these organotins exert toxic effects on the immune system, the bile duct, liver and pancreas. It has been supposed that similar to organoarsenic the toxicity of the dialkyltin compounds is related to reactions with biological dithiol groups. Therefore, in the present study, the antidotal effects of 2,3-dimercapto-propane-1-sulfonic acid (DMPS) and meso-2,3-dimercaptosuccinic acid (DMSA) on the organotoxic effects of dibutyltin dichloride (DBTC, single administration of 27 micromol kg(-1) b.w. i.v.) in rats were studied using different doses (100 and 500 micromol kg(-1) b.w.) and routes of administration (i.p. and p.o.) of both chelators. Several parameters of organotoxicity (thymus weight and cellularity, bile duct diameter, histological lesions of pancreas and liver, activities of amylase, lipase and alkaline phosphatase, bilirubin and hyaluronic acid in serum) were measured from 6 h to 8 weeks. 2. DMPS and DMSA diminished the DBTC induced bile duct, pancreas and liver lesions stronger than the thymus atrophy. Moreover, the development of a fibrosis of the pancreas and a cirrhosis of liver several weeks after single administration of DBTC to rats was inhibited by DMPS and DMSA. The antidotal effects on serum parameter were observed after both administration routes of the chelators. DMPS was more effective than DMSA in most measured parameters. The decrease in the biliary excretion of organotin by DMPS and DMSA seems to be the reason for the pronounced protective effects of DMPS and DMSA on bile duct, pancreas and liver. 3. For the treatment of poisonings with dibutyltin compounds, the administration of DMPS or DMSA can be recommended.
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Flora GJ, Arora U, Seth PK. Influence of combined therapeutic potential of meso 2,3-dimercaptosuccinic acid and calcium disodium edetate on lead-induced testicular alterations in rats. BIOMEDICAL AND ENVIRONMENTAL SCIENCES : BES 1999; 12:285-291. [PMID: 10840584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The therapeutic efficacy of a combination of meso 2,3-dimercaptosuccinic acid (DMSA) and calcium disodium EDTA in protecting testicular disorders in chronic lead intoxication was investigated. The results indicate that two five-days courses of the combined therapy produced a more effective recovery in the lead induced biochemical and histopathological disorders compared to conventional single 5 days therapy. No adverse effect of the chelators, when administered individually or in combination, was noticed in the testes of control (without lead exposure) animals.
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80
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Hottel TL, el-Refai NY, Jones JJ. A comparison of the effects of three chelating agents on the root canals of extracted human teeth. J Endod 1999; 25:716-7. [PMID: 10726535 DOI: 10.1016/s0099-2399(99)80115-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The effects of EDTA were compared in vitro with the effects of two other chelating agents: succimer and trientine HCl. Thirty extracted human teeth with single canals were used. Groups of 10 were treated by the three agents and then examined under the scanning electron microscope. The results showed that EDTA widened the dentinal tubules. Trientine HCl also produced widening of the dentinal tubules very similar to EDTA, whereas succimer produced more extensive widening.
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81
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Mishima K, Hidaka S, Takamura N, Shinozawa S. Protection against cis-diamminedichloroplatinum-induced nephrotoxicity by 2,3-dimercaptosuccinic acid in rats. Ren Fail 1999; 21:593-602. [PMID: 10586422 DOI: 10.3109/08860229909094153] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The present study was designed to examine the usefulness of 2,3-dimercaptosuccinic acid (DMSA) for the purpose of reducing cis-diamminedichloroplatinum (DDP)-induced nephrotoxicity and effective clinical use of DDP and safe. The effectiveness of DMSA on the DDP-excretion in rat kidney was observed by measuring the platinum concentration using Atomic Absorption Instrument. Co-administration of DMSA (1.0 or 2.0 mmol/kg) 1 hour after DDP injection (20 mumol/kg) showed more decrease in the platinum concentration than that immediately after DDP injection. The alleviating effect of DMSA on DDP toxicity was evaluated by lipid peroxidation, enzymatic antioxidants, and glutathione levels. The administration of DDP alone caused a significant increase in lipid peroxidation and significant decreases in enzymatic antioxidants and glutathione levels in the kidney. Co-administration of DMSA (2.0 mmol/kg) 1 hour after DDP injection showed the most effective reduction of these enzymatic damages caused by DDP. These findings suggested that the co-administration of DMSA (2.0 mmol/kg) 1 hour after DDP injection leads DDP to effective excrete from renal tissue and suppresses the lipid peroxide reaction and results in reduction of nephrotoxicity.
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82
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Lynn S, Yu GL, Yan K. Vicinal-thiol-containing molecules enhance but mono-thiol-containing molecules reduce nickel-induced DNA strand breaks. Toxicol Appl Pharmacol 1999; 160:198-205. [PMID: 10527919 DOI: 10.1006/taap.1999.8758] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Several thiol-containing molecules (TCM) are currently used as antidotes for nickel, and vicinal TCM seem to be more effective in mobilizing tissue nickel than are mono TCM. Using single cell alkaline electrophoresis, we have shown that the vicinal TCM, meso-2, 3-dimercaptosuccinic acid (DMSA), 2,3-dimercaptopropane-1-sulfonate, and 2,3-dimercaptopropanol markedly enhanced, whereas the mono TCM, D-penicillamide, glutathione, beta-mercaptoethanol, and diethyl dithiocarbomate, reduced nickel chloride (Ni)-induced DNA breaks in a human leukemia cell line, NB4 cells. Ni or TCM alone did not induce plasmid DNA breaks in test tubes and neither did Ni plus mono TCM; however, Ni plus vicinal TCM did. Vicinal TCM did, but mono TCM did not generate H(2)O(2) in solution. H(2)O(2) alone did not, but H(2)O(2) plus Ni induced plasmid DNA breaks. Although Ni plus glutathione did not break DNA, Ni plus glutathione plus H(2)O(2) did. The Ni-DMSA-induced DNA breaks in NB4 cells, as well as in plasmids, were completely prevented by d-mannitol or partially prevented by several antioxidants. Therefore, the DNA breaks induced by Ni plus vicinal TCM seem to be due to the complex of Ni with TCM in concert with the H(2)O(2) produced by the vicinal TCM. The results that DMSA at a concentration as low as 5 microM enhanced the Ni-induced DNA breaks suggest a further evaluation of the TCM as nickel chelators is needed.
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83
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Pokorski PL, McCabe MJ, Pounds JG. Lead inhibits meso-2,3-dimercaptosuccinic acid induced calcium transients in cultured rhesus monkey kidney cells. Toxicology 1999; 134:19-26. [PMID: 10413185 DOI: 10.1016/s0300-483x(99)00011-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previously we have shown that meso-2,3-dimercaptosuccinic acid (DMSA, 15-500 microM) elicits concentration-dependent increases in intracellular calcium levels ([Ca2+]i) in untreated rhesus monkey kidney cells (LLC-MK2) (Pokorski et al., 1997, unpublished results). Little is known about the restorative effects of the chelating agent 2,3-dimercaptosuccinic acid on intracellular calcium homeostasis in the presence of lead. Lead interacts at numerous sites in Ca2+ homeostasis and may mimic Ca2+ to interfere with Ca2+-mediated intracellular signaling. To examine the effects of lead on [Ca2+]i and DMSA-induced calcium transients, LLC-MK2 were plated on 35 mm coverslip dishes (10(4) cells/dish) and pre-treated with non-cytotoxic concentrations of lead (0-100 microM) for 24 h. Cells were washed, loaded with the calcium-sensitive probe Fura-2/AM, rinsed again, and examined in loading buffer in the absence of any additional lead. Intracellular calcium was measured using a dual-wavelength calcium imaging system. Basal [Ca2+]i levels did not change between Pb-exposed (0-50 microM, 24 h) and non-lead exposed cells. In cells treated with > or = 10 microM lead for 24 h, the ability of DMSA to elicit a calcium response was blocked. These results provide evidence that pre-exposure to lead blocks the entry of extracellular calcium into LLC-MK2 cells when stimulated by specific calcium mobilizing agents.
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84
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Gerhardsson L, Börjesson J, Mattsson S, Schütz A, Skerfving S. Chelated lead in relation to lead in bone and ALAD genotype. ENVIRONMENTAL RESEARCH 1999; 80:389-398. [PMID: 10330313 DOI: 10.1006/enrs.1998.3936] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In order to assess whether lead in bone is available for chelation by 2,3 meso-dimercaptosuccinic acid (DMSA), 21 workers (10 active and 11 retired) from a secondary lead smeltery were studied. A morning urine sample was obtained from all participants, followed by ingestion of 10 mg per kg body weight of the chelating agent DMSA. All urine produced during the following 24 h was collected in consecutive 6- and 18-h portions. Concentrations of lead in blood (B-Pb) and urine were determined by flameless atomic absorption spectrometry (AAS), in plasma (P-Pb) by inductively coupled plasma mass spectrometry (ICP-MS), and in finger bone (Bone-Pb) by K X-ray fluorescence technique (XRF). DMSA-chelatable lead excreted in the 24-h portion correlated well with the excretion in the 6-h portion (U-Pb6h; rs=0.95; P<0.001). U-Pb6h showed a non-linear relationship to B-Pb (rs=0.84; P<0.001) and linear relationships to P-Pb (rs=0. 91; P<0.001) and lead in morning urine (rs=0.95; P<0.001). In active workers, but not in retired ones, P-Pb and U-Pb6h showed some relationship to Bone-Pb. In alternative multiple regression models B-Pb or P-Pb were both significant predictors of U-Pb6h, while Bone-Pb did not significantly improve the models. It can, thus, be concluded that DMSA-chelatable lead mainly reflects lead concentrations in blood, soft tissues, and possibly also trabecular bone. It is not a good index of total body burden and long-term exposure. For such estimations cortical Bone-Pb is more valid, as it contains the major fraction of long-term accumulated lead in the body. Further, the mobilization test did not give better information than measurements of lead levels in blood, plasma, or urine without chelation.
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85
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Pigman EA, Lott JR, Fernando Q, Blanchard J. Use of the Caco-2 cell model to assess the relative lead-chelating ability of diasterioisomers of 2,3-dimercaptosuccinic acid. ENVIRONMENTAL HEALTH PERSPECTIVES 1999; 107:111-5. [PMID: 9924005 PMCID: PMC1566335 DOI: 10.1289/ehp.99107111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The purpose of this study was to examine the mechanisms of lead (Pb) uptake by human intestinal cells and to compare the intestinal transport and relative lead-chelating ability of two diastereoisomeric forms (i.e., meso and racemic) of 2, 3-dimercaptosuccinic acid (DMSA). The model used was the human adenocarcinoma (Caco-2) cell monolayer. The Caco-2 cells were cultured in flasks for examination of cellular uptake of lead and subsequent chelation of the lead by the DMSA isomers. For assessment of the comparative intestinal transport of the diastereoisomers, the Caco-2 cells were cultured on semipermeable supports. The effects of N-ethylmaleimide and 1,25-dihydroxyvitamin D3 (vitamin D3) on the uptake of lead by the Caco-2 monolayer were examined to determine the contributions of sulfhydryl-binding and calcium-binding protein, respectively, to the lead uptake process. Analysis of lead was performed using both macro- and micro-proton-induced X-ray emission (PIXE), and DMSA was measured spectrophotometrically following derivatization with 5,5'-dithiobis-2-nitrobenzoic acid. Results from micro-PIXE imaging suggest that lead is bound on the surface of the cell, and that sulfhydryl binding may be an important step in the uptake of lead by the Caco-2 cells. Macro-PIXE results indicate that the racemic form of DMSA may be more effective in chelating lead from within the cell. Comparison of the transport of the two DMSA diastereoisomers indicates that the racemic form is transported across the Caco-2 monolayer more readily than the meso form.
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86
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Cosquer A, Pichereau V, Le Mée D, Le Roch M, Renault J, Carboni B, Uriac P, Bernard T. Toxicity and osmoprotective activities of analogues of glycine betaine obtained by solid phase organic synthesis towards Sinorhizobium meliloti. Bioorg Med Chem Lett 1999; 9:49-54. [PMID: 9990455 DOI: 10.1016/s0960-894x(98)00679-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Seven analogues of the bacterial osmoprotectant glycine betaine (GB, trimethylammonioacetate), in which the methyl groups of the Me3N+ moiety are replaced by various substituents, were obtained by SPOS using Wang resin. Their biological activities (osmoprotection vs toxicity), appeared closely related to their uptake efficiency and their catabolism in the betaine-demethylating model bacterium Sinorhizobium meliloti.
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87
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Chen S, Golemboski KA, Sanders FS, Dietert RR. Persistent effect of in utero meso-2,3-dimercaptosuccinic acid (DMSA) on immune function and lead-induced immunotoxicity. Toxicology 1999; 132:67-79. [PMID: 10199582 DOI: 10.1016/s0300-483x(98)00139-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Meso-2,3-dimercaptosuccinic acid (DMSA) is a drug currently employed for cheltion therapy in lead poisoning; however, little is known about its potential effects on the immune system. To examine the effect of DMSA and its capacity to reverse immunotoxicity resulting from exposure to lead in utero, female Fischer 344 rats were administered lead acetate in drinking water from 2 weeks prior to mating until parturition; DMSA was given by gavage on days 6-21 of gestation. The immune function of the female offspring was tested at 13 weeks of age. The results showed that lead (250 ppm) suppressed Th1-type responses (delayed-type hypersensitivity (DTH), interferon gamma (IFN gamma) production), enhanced a Th2-type response (interleukin-4 (IL-4) production), and increased tumor necrosis factor alpha (TNF alpha) production from macrophages. DMSA treatment (60 mg/kg per day) during pregnancy significantly lowered the blood lead levels of both the embryos and the lactating dams as well as the milk lead level of lactating dams. The chelation treatment also reversed the lead-induced alterations in pup body weight, relative spleen weight, TNF alpha, and IL-4 production. But in utero exposure to DMSA alone resulted in decreased DTH response in adult offspring. This was likely due to a reduced cell recruitment, since plasma monocyte chemoattractant protein-1 (MCP-1) levels were decreased. The DMSA-exposed offspring also demonstrated increased interleukin-2 (IL-2) production. These results suggest that DMSA reverses some of the lead-induced immunotoxicity; however, this treatment itself during embryonic development produces subsequent adult immunomodulation.
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88
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Reymond JM, Desmeules J. Sodium stibogluconate (pentostan) overdose in a patient with acquired immunodeficiency syndrome. Ther Drug Monit 1998; 20:714-6. [PMID: 9853993 DOI: 10.1097/00007691-199812000-00023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A 32-year-old man with acquired immunodeficiency syndrome (AIDS) admitted to the hospital for treatment of visceral leishmaniasis was inadvertently given 10 times the prescribed first dose of sodium stibogluconate ([Sb] 6.5 g instead of 0.65 g). He experienced no immediate major toxicity during the first 48 hours, but a significant rise of pancreatic enzyme activities was observed (amylase at 10 times the upper limit of normal, lipase at 50 times the upper limit of normal) without clinical signs or indications on computed tomography (CT) of pancreatitis. The third day after the overdose, he developed appendicitis, which appeared coincidental; he recovered uneventfully from surgery. Most of the overdose of Sb was eliminated within the first few hours. Pharmacokinetics remained linear; the rapid, long elimination half-lives (2.7 hours and 54 hours, respectively) were similar to those in previously published results. The administration of a chelating agent, dimercaptosuccinic acid (DMSA), 72 hours after the Sb overdose did not modify the pharmacokinetics of the medication.
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89
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Neal R, Cooper K, Gurer H, Ercal N. Effects of N-acetylcysteine and 2,3-dimercaptosuccinic acid on lead induced oxidative stress in rat lenses. Toxicology 1998; 130:167-74. [PMID: 9865483 DOI: 10.1016/s0300-483x(98)00104-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Lead (Pb) is known to disrupt the pro-oxidant/anti-oxidant balance of tissues which leads to biochemical and physiological dysfunction. The present study investigated the effects of exposure on the redox status of the lenses of Fisher 344 rats and examined whether antioxidant or chelator administration reversed these changes. Animals were given 5 weeks of 2000 ppm Pb exposure followed by 1 week of either antioxidant, chelator or distilled water administration. Glutathione (GSH) and cysteine (CYS) levels decreased in the Pb-exposed group. N-acetylcysteine or 2,3-dimercaptopsuccinic acid (Succimer) supplementation following Pb intoxication resulted in increases in the GSH and CYS levels. Protein bound glutathione (PSSG) and cysteine (PSSC) increased following Pb exposure. In the Succimer-treated animals, the PSSG decreased significantly. The glutathione disulfide (GSSG) levels remained unchanged. Malondialdehyde (MDA) levels, a major lipid peroxidation byproduct, increased following Pb exposure and decreased following Succimer treatment. Our results suggest that antioxidant supplementation, as well as chelation, following Pb exposure may enhance the reductive status of lenses.
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90
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Tandon SK, Singh S, Prasad S, Mathur N. Mobilization of lead by calcium versenate and dimercaptosuccinate in the rat. Clin Exp Pharmacol Physiol 1998; 25:686-92. [PMID: 9750957 DOI: 10.1111/j.1440-1681.1998.tb02277.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
1. Calcium disodium ethylenediaminetetraacetate (CaNa2 EDTA) and meso-2,3-dimercaptosuccinic acid (DMSA) individually and in permutation-combination in various doses (0.1, 0.2 and 0.4 mmol/kg bodyweight) were investigated for their efficacy to mobilize lead from vital tissues into urine and faeces and to restore the lead-sensitive biochemical parameters in lead pre-exposed rats with a view to develop the most acceptable treatment regimen for lead poisoning with a minimal loss of endogenous essential elements. 2. The combined therapy was more effective than a single chelator treatment. 3. The combination of 0.2 mmol/kg CaNa2EDTA + 0.4 mmol/kg DMSA caused a lower depletion of zinc, calcium and iron but possessed almost equal capability to that of 0.4 mmol/kg CaNa2EDTA + 0.4 mmol/kg DMSA to produce urinary as well as faecal excretion of lead, to reduce the tissue burden of lead, including that of the brain, and to reverse lead-induced biochemical alterations. 4. The combination of 0.2 mmol/kg CaNa2EDTA + 0.4 mmol/kg DMSA has shown a definite improvement over previously reported combinations in terms of removal of lead from tissues, particularly the brain, restoration of urinary delta-aminolevulinic acid levels and a decrease in the loss of body zinc and is, therefore, recommended for the treatment of lead intoxication.
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91
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Gürer H, Ozgünes H, Neal R, Spitz DR, Erçal N. Antioxidant effects of N-acetylcysteine and succimer in red blood cells from lead-exposed rats. Toxicology 1998; 128:181-9. [PMID: 9750041 DOI: 10.1016/s0300-483x(98)00074-2] [Citation(s) in RCA: 145] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study examined whether lead-induced alterations in selected parameters that are indicative of oxidative stress accompany the toxic effects of lead in red blood cells (RBCs) in vivo. It also explored the possibility that treatment with N-acetylcysteine (NAC) or succimer (meso-2,3-dimercaptosuccinic acid) was capable of reversing parameters indicative of lead-induced oxidative stress. Fisher 344 rats were given 2000 ppm lead acetate in their drinking water for 5 weeks. The lead was then removed and the animals were given NAC (800 mg/kg/day) or succimer (90 mg/kg/day) in their drinking water for 1 week, after which the RBCs were harvested. Animals not given lead and those given lead, but not NAC or succimer, served as negative and positive controls, respectively. At the end of the experiment, blood-lead levels were 35 +/- 4 microg/dl in lead-treated animals, which were reduced to 2.5 +/- 1 microg/dl by treatment with succimer and to 25 +/- 3 microg/dl by treatment with NAC. Lead-exposed animals demonstrated signs of anemia as evidenced by anisocytosis, poikilocytosis, and alterations in hemoglobin, hematocrit, and mean corpuscular volume. Lipid peroxidation, as evidenced by increased malondialdehyde (MDA) content, as well as decreases in reduced glutathione (GSH) and increases in catalase and glucose 6-phosphate dehydrogenase (G6PD) activity were noted in RBCs from lead-treated rats, suggesting that the lead induced oxidative stress. In addition, a significant reduction in blood delta-aminolevulinic acid dehydratase (ALAD) activity suggested that accumulation and autooxidation of delta-aminolevulinic acid might contribute to lead-induced oxidative stress. Treatment with either NAC or succimer reversed lead-induced alterations in MDA and GSH content, but only succimer appeared to partially restore ALAD activity. These results provide in vivo evidence supporting the hypothesis that lead induces oxidative stress in RBCs, which is reversible by treatment with a thiol antioxidant (NAC), as well as a chelating agent (succimer).
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92
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Wray GM, Hinds CJ, Thiemermann C. Effects of inhibitors of poly(ADP-ribose) synthetase activity on hypotension and multiple organ dysfunction caused by endotoxin. Shock 1998; 10:13-9. [PMID: 9688085 DOI: 10.1097/00024382-199807000-00003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The nuclear enzyme poly(ADP-ribose) synthetase (PARS) is activated by DNA strand breakage, caused, for example by nitric oxide (NO), peroxynitrite, or oxygen-derived free radicals. Activation of PARS can cause intracellular energy depletion and cell death in vitro and may play a role in the circulatory and organ failure caused by endotoxin (LPS). Here we investigate the effects of various chemically distinct inhibitors of PARS activity (3-aminobenzamide, nicotinamide, 1,5-dihydroxyisoquinoline) on circulatory failure and organ dysfunction caused by LPS in the rat. Administration of endotoxin caused circulatory failure, acute renal dysfunction, hepatocellular injury and dysfunction, pancreatic injury, elevation of plasma lactate levels, and overproduction of NO. None of the PARS inhibitors used reduced the circulatory failure, the renal dysfunction, rise in lactate, or the overproduction of NO caused by LPS. Although 1,5-dihydroxyisoquinoline (ISO) attenuated the rises in the serum levels of bilirubin, alanine aminotransferase (ALT) (indicators of liver injury/dysfunction), and lipase (indicator of pancreatic injury); a similar effect was also observed with the vehicle for ISO, dimethyl sulfoxide (DMSO), which is a well known scavenger of hydroxyl radicals. Thus, the beneficial effects of ISO are unlikely to be due to inhibition of PARS activity, but may be due to the scavenging of free radicals by its vehicle DMSO. Activation of PARS does not contribute to the circulatory failure, renal dysfunction, lactic acidosis, or the overproduction of NO and is unlikely to contribute to the liver injury/dysfunction caused by endotoxic shock in the rat.
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93
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de la Torre A, Bellés M, Llobet JM, Mayayo E, Domingo JL. Comparison of the effectiveness of 2,3-dimercaptopropanol (BAL) and meso-2,3-dimercaptosuccinic acid (DMSA) as protective agents against mercuric chloride-induced nephrotoxicity in rats. Biol Trace Elem Res 1998; 63:1-10. [PMID: 9764565 DOI: 10.1007/bf02785272] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The effectiveness of 2,3-dimercaptopropanol (BAL) and meso-2,3-dimercaptosuccinic acid (DMSA) on HgCl2-induced nephrotoxicity was studied in the rat. Seven groups of adult male rats were given a single sc toxic dose of HgCl2 (0.68 mg/kg) followed by 0.9% saline (positive control group), BAL (15, 30, and 60 mg/kg) or DMSA (50, 100, and 200 mg/kg) administered ip at 0, 24, 48, and 72 h thereafter. Although the renal function of HgCl2-exposed rats was slightly improved after BAL administration, Hg concentrations in the kidney were only reduced at 60 mg/kg. In addition, the protective effect of BAL was not dose-related. In contrast to BAL, DMSA was effective in increasing the urinary excretion of Hg and in reducing the renal Hg content. These results show that DMSA would be more effective than BAL in preventing or in protecting against inorganic Hg-induced nephrotoxicity.
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94
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Aaseth J, Korkina LG, Afanas'ev IB. Hemolytic activity of copper sulfate as influenced by epinephrine and chelating thiols. ZHONGGUO YAO LI XUE BAO = ACTA PHARMACOLOGICA SINICA 1998; 19:203-6. [PMID: 10375726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
AIM To study the effects of epinephrine, homocysteine, and other complexing agents on the cytotoxicity of copper sulfate. METHODS In vitro suspensions of human red cells incubated with cupric sulfate were used, and hemolysis was determined by extracellular hemoglobin. RESULTS The hemolytic activity of CuSO4 (0.3 mmol.L-1) was enhanced by the presence of epinephrine and to a lesser extent by homocysteine, whereas D-penicillamine, succimer, and mercaptodextran reduced the copper-induced hemolysis. The latter 3 chelating thiols also reduced the copper-epinephrine-induced hemolysis. The plasma protein ceruloplasmin reduced markedly the copper-epinephrine-induced hemolysis, even upon concentrations < 20% of that of copper. Chromic chloride, as well, acted anti-hemolytically. CONCLUSION The latter protectors may interact with the production or activity of toxic oxygen, while classical copper chelators sequester cupric ions from interaction with epinephrine or homocysteine.
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95
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Nathan I, Ben-Valid I, Henzel R, Masalha H, Baram SN, Dvilansky A, Parola AH. Alterations in membrane lipid dynamics of leukemic cells undergoing growth arrest and differentiation: dependency on the inducing agent. Exp Cell Res 1998; 239:442-6. [PMID: 9521862 DOI: 10.1006/excr.1997.3914] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effect of various differentiation inducers on membrane cell dynamics was studied using HL-60 and K562 leukemic cell lines. Membrane lipid dynamics was measured by the steady-state fluorescence polarization (P) method utilizing either 1,6-diphenyl-1,3,5-hexatriene (DPH) or the trimethyl ammonium derivative of DPH (TMA-DPH), which ascertains anchorage of the label to the membrane-water-lipid interface. Decrease in membrane microfluidity was observed in HL-60 cells undergoing differentiation into macrophages by 1,25-dihydroxyvitamin D3 and by K562 cells induced to differentiate by DMSO. Sodium butyrate caused an increase in membrane fluidity in K562 cells undergoing differentiation into erythroid-like cells while in HL-60 cells a dual effect was observed. At 0.4 mM concentration, in which the cells were induced to differentiate along the monocyte pathway, a decrease in membrane fluidity was observed, while at 1 mM concentration an increase in membrane fluidity occurred. Interferon-gamma (IFN-gamma) induced an increase in membrane fluidity in both cell lines. Using HL-60 cells fluorescently labeled by TMA-DPH, similar results indicating fluidization of the membrane following IFN-gamma treatment were obtained. Advanced fluorescence lifetime measurements, evaluated either by phase modulation spectrofluorometry or by single photon correlation fluorometry confirmed that the decrease in fluorescence polarization by IFN-gamma resulted from membrane fluidization and not from elongation of the probe's excited state lifetime. It is suggested that the inducer mode of action, and not the differentiation route, determine the outcome of changes in membrane microviscosity.
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MESH Headings
- Butyrates/pharmacology
- Butyric Acid
- Calcitriol/pharmacology
- Cell Differentiation/drug effects
- Cell Division/drug effects
- Diphenylhexatriene/analogs & derivatives
- Fluorescence Polarization
- Fluorescent Dyes
- HL-60 Cells/drug effects
- HL-60 Cells/metabolism
- Humans
- Interferon-gamma/pharmacology
- Leukemia, Erythroblastic, Acute/metabolism
- Leukemia, Erythroblastic, Acute/pathology
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Membrane Fluidity/drug effects
- Membrane Lipids/metabolism
- Recombinant Proteins
- Succimer/pharmacology
- Tumor Cells, Cultured/drug effects
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96
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Tripathi N, Flora SJ. Effects of some thiol chelators on enzymatic activities in blood, liver and kidneys of acute arsenic (III) exposed mice. BIOMEDICAL AND ENVIRONMENTAL SCIENCES : BES 1998; 11:38-45. [PMID: 9559101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The effects of meso 2, 3-dimercaptosuccinic acid (DMSA), sodium 2, 3-dimercaptopropane 1-sulfonate (DMPS) and S-adenosyl L-methionine (SAM) on the enzymatic activities of mice were studied. The mice were given intraperitoneal (i.p.) injections of these chelating agents (1 mmol/kg) and 3 h later the activity of delta-aminolevulinic acid dehydratase (ALAD) in the blood, and aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltranspeptidase (gamma-GT), alkaline phosphatase (ALP) in the liver and kidney were determined. The activity of blood ALAD was significantly increased by the administration of DMSA and SAM while DMPS had only a moderate effect. The activities of other hepatic enzymes changed little when the mice were treated with these chelating agents, except for a significant reduction in hepatic ALP activity following DMPS administration. Arsenic (III) administration markedly increased the activities of ALT and ALP in the liver and kidneys. The changes in the enzymatic activities by treatment with arsenic were prevented by injection of DMSA, DMPS and SAM, DMSA being the most effective. These results indicate that DMSA, DMPS and SAM were not toxic to the liver or kidneys of mice and that treatment with DMSA is more effective than DMPS or SAM in protecting mice from acute hepatic or renal toxicity caused by arsenic.
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97
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Misra M, Behari JR. Effect of liposome-encapsulated meso-2,3-dimercaptosuccinic acid on mice exposed to lead through drinking water. BOLLETTINO CHIMICO FARMACEUTICO 1997; 136:611-4. [PMID: 9528168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Liposomes are the potent carriers of therapeutic drugs for their targeted delivery to the intracellular sites specially when the drug is hydrophilic in nature and is unable to cross the cell membrane. Lead, a major source of environmental pollution, is accumulated in the body system of both animals and humans through reticuloendothelial system, the site where liposomes also get engulfed upon their entry into the body. In view of these considerations, meso-2,3 dimercaptosuccinic acid (DMSA), a potent chelating drug used in heavy metals intoxication, specially lead, was encapsulated in small unilamellar liposomes composed of phosphatidyl-choline and cholesterol (1:1) and used to evaluate its efficacy in lead intoxication. DMSA either in free form or encapsulated in liposomes was administered intravenously (2,62 mumoles/kg, three injections at a gap of 48 hours each, total 7.85 mumoles/kg) to mice which were pre-fed with lead in drinking water (500 micrograms/ml) for one month. It was found that only DMSA encapsulated in liposomes was significantly effective in reducing the level of lead in liver, kidneys and spleen at the dose administered. DMSA either in free form or encapsulated in liposomes also restored the inhibition in blood delta-aminolevulinic acid dehydratase (delta-ALAD) activity. The results suggest that liposome encapsulated DMSA may be preferred over free DMSA for reducing the body burden of lead.
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98
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Yan H, Carter CE, Xu C, Singh PK, Jones MM, Johnson JE, Dietrich MS. Cadmium-induced apoptosis in the urogenital organs of the male rat and its suppression by chelation. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH 1997; 52:149-68. [PMID: 9310147 DOI: 10.1080/00984109708984058] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cadmium-induced apoptosis is shown to occur, in vivo, in several organs of the male Wistar rat urogenital system, 48 h after cadmium administration i.p. at a dose of 0.03 mmol/kg. Characteristic DNA fragmentation (as measured by an enzyme-linked immunosorbent-assay, ELISA) and histopathologically observed changes characteristic of apoptosis are found in the kidney, prostate, seminal vesicles, testes, and epididymis. TUNEL assay also demonstrates the apoptosis. Such changes are absent from bladder and vas deferens tissue. Timely administration of an appropriate chelating agent capable of reaching intracellular cadmium binding sites can suppress the processes leading to apoptosis. Administration of monoisomyl meso-2,3-dimercaptosuccinate (Mi-ADMS, 0.5 mmol/kg i.p.) to cadmium-treated rats is effective in greatly reducing typical histopathologic signs of apoptosis and the associated chromatin DNA fragmentation as revealed by ELISA when the antagonist is administered 1 h after cadmium. Administration of the chelating agent at law times results in greater degradation of DNA into oligonucleotides and more prominent histopathological evidence of apoptotic changes in the affected organs of the rat urogenital system. There is also a progressive increase in apoptotic changes indicated by TUNEL assay, as the antagonist is administered at progressively greater intervals after cadmium.
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99
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Bernal J, Lee JH, Cribbs LL, Perez-Reyes E. Full reversal of Pb++ block of L-type Ca++ channels requires treatment with heavy metal antidotes. J Pharmacol Exp Ther 1997; 282:172-80. [PMID: 9223552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The mechanisms of Pb++ block and unblock of L-type Ca++ channel currents were measured using ventricular myocytes or the cloned channel. The cloned channel was expressed in either Xenopus laevis oocytes or human embryonic kidney cells (HEK 293, stable transfectants). The threshold for Pb++ block was 1 nM, and the apparent IC50 value was 152 nM in oocytes and 169 nM in HEK 293 cells. Pb++ block was dependent on the composition of the external recording solution but not dependent on the subunit composition of the channel. Pb++ block was voltage dependent, with little block observed at negative test potentials using low concentrations of Pb++. Strong depolarizations (>+100 mV) reversed Pb++ block, allowing measurement of reblock kinetics. Reblock was fast (tau = 11 msec), as measured during a +20-mV test pulse. Simple washout did not completely reverse Pb++ block, especially after exposure to concentrations of >100 nM. Full recovery could only be observed after treatment with heavy metal antidotes such as meso-2,3-dimercaptosuccinic acid, 2,3-dimercapto-1-propanesulfonic acid and EDTA. These results suggest that Pb++ blocks voltage-gated Ca++ channels by two mechanisms and that full reversal of lead block requires chelator treatment.
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100
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Shah DT, Walker EM, Jones MM, Singh PK, Larsen B. Inhibitory effects of seven organosulphur compounds on clinical isolates of Candida species in vitro. ANNALS OF CLINICAL AND LABORATORY SCIENCE 1997; 27:282-6. [PMID: 9210973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Thirty clinical isolates of Candida albicans and 10 other Candida species were tested for susceptibility to 6 substituted dithiocarbamates and one dimercaptosuccinate. Dimethyldithiocarbamate, sodium pyrrolidine dithiocarbamate, and sodium diethyldithiocarbamate showed dose-dependent antifungal activity which was partially reversed by the addition of zinc, copper, or iron sulfate with greatest reversal at 2:1 metal to dithiocarbamate molar ratio. Anaerobiosis also interfered with dithiocarbamate antifungal activity.
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