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Hassanin M, Kerek E, Chiu M, Anikovskiy M, Prenner EJ. Binding Affinity of Inorganic Mercury and Cadmium to Biomimetic Erythrocyte Membranes. J Phys Chem B 2016; 120:12872-12882. [DOI: 10.1021/acs.jpcb.6b10366] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mohamed Hassanin
- Department
of Biological Sciences and ‡Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Evan Kerek
- Department
of Biological Sciences and ‡Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Michael Chiu
- Department
of Biological Sciences and ‡Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Max Anikovskiy
- Department
of Biological Sciences and ‡Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Elmar J. Prenner
- Department
of Biological Sciences and ‡Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
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The structural and functional effects of Hg(II) and Cd(II) on lipid model systems and human erythrocytes: A review. Chem Phys Lipids 2015; 193:36-51. [PMID: 26455331 DOI: 10.1016/j.chemphyslip.2015.09.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 09/26/2015] [Accepted: 09/28/2015] [Indexed: 01/24/2023]
Abstract
The anthropogenic mobilization of mercury and cadmium into the biosphere has led to an increased and ineludible entry of these metals into biological systems. Here we discuss the impact of Hg(II) and Cd(II) on lipid model systems and human erythrocytes from a biophysical perspective. After a brief introduction to their implications on human health, studies that have investigated the effects of Hg(II) and Cd(II) on lipid model systems and human erythrocytes are discussed. In terms of lipids as toxicological target sites, predominantly variations in lipid head groups have been the source of investigation. However, as research in this field progresses, the effects of Hg(II) and Cd(II) on other structural features, such as acyl chain length and unsaturation, and other important lipid components and complex biomimetic lipid mixtures, will require further examinations. This review provides an analysis of what has been learned collectively from the diverse methodologies and experimental conditions used thus far. Consequently, there is a need for more comprehensive and thorough investigations into the effects of Hg(II) and Cd(II) on lipid membranes under consistent experimental conditions such as pH, ionic strength, temperature, and choice of lipid model system.
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Guan J, Wang YC, Gunasekaran S. Using L-Arginine-Functionalized Gold Nanorods for Visible Detection of Mercury(II) Ions. J Food Sci 2015; 80:N828-33. [DOI: 10.1111/1750-3841.12811] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Accepted: 12/23/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Jiehao Guan
- Dept. of Biological Systems Engineering; Univ. of Wisconsin-Madison; 460 Henry Mall Madison WI U.S.A
| | - Yi-Cheng Wang
- Dept. of Biological Systems Engineering; Univ. of Wisconsin-Madison; 460 Henry Mall Madison WI U.S.A
| | - Sundaram Gunasekaran
- Dept. of Biological Systems Engineering; Univ. of Wisconsin-Madison; 460 Henry Mall Madison WI U.S.A
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Laporte JM, Ribeyre F, Truchot JP, Boudou A. Experimental study of the combined effects of pH and salinity on the bioaccumulation of inorganic mercury in the crayfish Astacus leptodactylus. CHEMICAL SPECIATION & BIOAVAILABILITY 2015. [DOI: 10.1080/09542299.1996.11083261] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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5
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Mercury increases water permeability of a plant aquaporin through a non-cysteine-related mechanism. Biochem J 2013; 454:491-9. [PMID: 23819815 DOI: 10.1042/bj20130377] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Water transport across cellular membranes is mediated by a family of membrane proteins known as AQPs (aquaporins). AQPs were first discovered on the basis of their ability to be inhibited by mercurial compounds, an experiment which has followed the AQP field ever since. Although mercury inhibition is most common, many AQPs are mercury insensitive. In plants, regulation of AQPs is important in order to cope with environmental changes. Plant plasma membrane AQPs are known to be gated by phosphorylation, pH and Ca²⁺. We have previously solved the structure of the spinach AQP SoPIP2;1 (Spinacia oleracea plasma membrane intrinsic protein 2;1) in closed and open conformations and proposed a mechanism for how this gating can be achieved. To study the effect of mercury on SoPIP2;1 we solved the structure of the SoPIP2;1-mercury complex and characterized the water transport ability using proteoliposomes. The structure revealed mercury binding to three out of four cysteine residues. In contrast to what is normally seen for AQPs, mercury increased the water transport rate of SoPIP2;1, an effect which could not be attributed to any of the cysteine residues. This indicates that other factors might influence the effect of mercury on SoPIP2;1, one of which could be the properties of the lipid bilayer.
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6
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Le MT, Hassanin M, Mahadeo M, Gailer J, Prenner EJ. Hg- and Cd-induced modulation of lipid packing and monolayer fluidity in biomimetic erythrocyte model systems. Chem Phys Lipids 2013; 170-171:46-54. [PMID: 23523984 DOI: 10.1016/j.chemphyslip.2013.03.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 01/31/2013] [Accepted: 03/05/2013] [Indexed: 01/05/2023]
Abstract
The public health consequences that are associated with the low level exposure of various human populations to Cd(2+) and Hg(2+) are incompletely understood. In order to assess if interactions between these inorganic pollutants and erythrocyte biomembranes may contribute to their chronic toxicity, we have used a Langmuir trough to probe the effect of HgCl2 and CdCl2 on the packing and elasticity properties of biomimetic lipid monolayers using different lipid mixtures. These lipid films were deposited at room temperature on a biologically relevant subphase (1mM phosphate, 100mM NaCl at pH 7.4) in the absence and presence of 100μM HgCl2, CdCl2 and 1:1 mixtures thereof. The interactions of heavy metals with the lipids were monitored as changes in the surface pressure (π)-area (A) isotherms. In addition, metal induced changes to the elastic properties of the model systems were analyzed by area and compressibility data of phosphatidylcholine (PC) systems containing 0, 15, 30, 45 and 100% phosphatidylethanolamine (PE) and phosphatidylserine (PS). These mixtures revealed changes in lateral lipid packing as indicated by area expansion as well as enhanced film rigidity. The results demonstrate that both heavy metals affected the various lipid matrices, but metal mixtures showed the strongest impact. Based on these data, the adverse interaction of Hg(2+) and Cd(2+) with lipid bilayer membranes is identified as a feasible mechanism by which these toxic metals exert toxicity in mammalian cells. Interestingly, these metal interactions were found to depend on the lipid composition.
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Affiliation(s)
- Mary T Le
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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7
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Hg2+ and Cd2+ interact differently with biomimetic erythrocyte membranes. Biometals 2008; 22:261-74. [DOI: 10.1007/s10534-008-9162-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Accepted: 08/29/2008] [Indexed: 11/25/2022]
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8
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Lahajnar G, Pečar S, Sepe A. Na-nitroprusside and HgCl2 modify the water permeability and volume of human erythrocytes. Bioelectrochemistry 2007; 70:462-8. [DOI: 10.1016/j.bioelechem.2006.07.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2006] [Revised: 06/27/2006] [Accepted: 07/11/2006] [Indexed: 10/24/2022]
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Suwalsky M, Ungerer B, Villena F, Cuevas F, Sotomayor CP. HgCl2 disrupts the structure of the human erythrocyte membrane and model phospholipid bilayers. J Inorg Biochem 2000; 81:267-73. [PMID: 11065190 DOI: 10.1016/s0162-0134(00)00105-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The structural effects of Hg(II) ions on the erythrocyte membrane were studied through the interactions of HgCl2 with human erythrocytes and their isolated resealed membranes. Studies were carried out by scanning electron microscopy and fluorescence spectroscopy, respectively. Hg(II) induced shape changes in erythrocytes, which took the form of echinocytes and stomatocytes. This finding means that Hg(II) locates in both the outer and inner monolayers of the erythrocyte membrane. Fluorescence spectroscopy results indicate strong interactions of Hg(II) ions with phospholipid amino groups, which also affected the packing of the lipid acyl chains at the deep hydrophobic core of the membrane. HgCl2 also interacted with bilayers of dimyristoylphosphatidylcholine and dimyristoylphosphatidylethanolamine, representative of phospholipid classes located in the outer and inner monolayers of the erythrocyte membrane, respectively. X-ray diffraction indicated that Hg(II) ions induced molecular disorder to both phospholipid bilayers, while fluorescence spectroscopy of dimyristoylphosphatidylcholine large unilamellar vesicles confirmed the interaction of Hg(II) ions with the lipid polar head groups. All these findings point to the important role of the phospholipid bilayers in the interaction of Hg(II) on cell membranes.
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Affiliation(s)
- M Suwalsky
- Faculty of Chemical Sciences, University of Concepción, Chile.
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Girault L, Boudou A, Drfourc EJ. Methyl mercury interactions with phospholipid membranes as reported by fluorescence, 31P and 199Hg NMR. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1325:250-62. [PMID: 9168150 DOI: 10.1016/s0005-2736(96)00263-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Methylmercury (CH3Hg(II)) interactions with multilamellar vesicles of dimyristoyl(DM)- and dipalmitoyl(DP)-phosphatidylcholine (PC), -phosphatidic acid (PA), -phosphatidylglycerol (PG), -phosphatidylserine (PS) and -phosphatidylethanolamine (PE) have been investigated from the metal viewpoint by solution 199Hg-NMR and from the membrane side by diphenylhexatriene fluorescence polarization and solid state 31P-NMR. Results can be summarized as follows: (1) CH3Hg(II) strong binding to membranes results in a progressive decrease of the free CH3HgOH 199Hg-NMR isotropic signal and because of a slow exchange, in the NMR time scale, between free and bound methylmercury pools the lipid/water partition coefficients, K(lw), of the CH3HgOH species can be determined in the lamellar gel (fluid) phase. It is found: K(lw)(DMPC) approximately 2 +/- 2 (2 +/- 2); K(lw)(DMPE) approximately 7 +/- 3 (16 +/- 3); K(lw)(DMPG) = 170 +/- 10 (110 +/- 10); K(lw)(DMPS) = 930 +/- 50 (1250 +/- 60); K(lw)(DMPA) = 1250 +/- 60 (300 +/- 20). CH3Hg(II) interactions with membrane phospholipids are therefore electrostatic in nature and the phosphate moiety is proposed as a potential binding site. (2) The presence of CH3HgOH stabilizes the PG gel phase and destabilizes that of PS. No effect is observed on PC, PA and PE thermotropism. (3) methylmercury promotes the formation of isotropic 31P-NMR lines with PG, PA and PE systems suggesting the presence of non-bilayer phases and hence membrane reorganization. The above effects are compared to those of inorganic mercury Hg(II) and discussed in the context of cell toxicity.
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Affiliation(s)
- L Girault
- Centre de Recherche Paul Pascal, CNRS, Pessac, France
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Girault L, Lemaire P, Boudou A, Debouzy JC, Dufourc EJ. Interactions of inorganic mercury with phospholipid micelles and model membranes. A 31P-NMR study. EUROPEAN BIOPHYSICS JOURNAL : EBJ 1996; 24:413-21. [PMID: 8765713 DOI: 10.1007/bf00576713] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The binding of inorganic mercury Hg(II) to phospholipid headgroups has been investigated by phosphorus-31 nuclear magnetic resonance of phosphatidylethanolamine (PE), phosphatidylserine (PS) and phosphatidylcholine (PC) in water micellar and multilamellar phases. HgCl2 triggers the aggregation of phospholipid micelles, leading to a lipid-mercury precipitate that is no longer detectable by high-resolution 31P-NMR. The remaining signal area corresponds to micelles in the soluble fraction and is a non-linear function of the initial mercury-to-lipid molar ratio. Kinetics of micelle aggregation are exponential for the first 15 min and show a plateau tendency after 120 min. Apparent Hg(II) affinities for phospholipid headgroups are in the order: PE > PS > PC. The same binding specificity is observed when HgCl2 is added to (1:1) mixtures of different micelles (PE + PC; PS + PC). However, mercury binding to mixed micelles prepared with two lipids (PE/PC or PS/PC) induces the aggregation of both lipids. Hg(II) also leads to a 31P-NMR chemical shift anisotropy decrease of PC, PS and mixed (1:1) PE/PC multilamellar vesicles and markedly broadens PS spectra. This indicates that HgCl2 binding forces phospholipid headgroups to reorient and that the concomitant network formation leads to a slowing down of PS membrane collective motions. Formation of a gel-like lamellar phase characterized by a broad NMR linewidth is also observed upon HgCl2 binding to PE samples both in fluid (L alpha) or hexagonal (H(II)) phases. The PE hexagonal phase is no longer detected in the presence of HgCl2. Mixed PE/PC dispersions remain in the fluid phase upon mercury addition, indicating that no phase separation occurs. Addition of excess NaCl leads to the appearance of the non-reactive species HgCl4(2-) and induces the reversal of all the above effects.
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Affiliation(s)
- L Girault
- Centre de Recherche Paul Pascal, CNRS, Pessac, France
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12
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Delnomdedieu M, Allis JW. Interaction of inorganic mercury salts with model and red cell membranes: importance of lipid binding sites. Chem Biol Interact 1993; 88:71-87. [PMID: 8330326 DOI: 10.1016/0009-2797(93)90085-d] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The effect of two mercury salts, HgCl2 and Hg(NO3)2, on the thermotropic properties of phosphatidylserine (PS) model membranes and sonicated rat red cell membranes was investigated by fluorescence polarization. Both Hg(II) salts abolished the phase transition and decreased the membrane fluidity by interacting with PS. Maximal effect was observed at a Hg/PS ratio of 2.5-5 for mercuric chloride and at 1.5 for the nitrate salt. For both mercury compounds, 10 mM NaCl protected model membranes from the effects of Hg(II). HgCl2 and Hg(NO3)2 also decreased the fluidity of rat red cell membranes. Maximal effect was observed for 0.4 mM HgCl2 and 0.6 mM Hg(NO3)2, with 0.0125 mg protein/ml. Addition of NaCl to the Hg(II)-red cell system decreased the Hg(II)-induced perturbation of the thermotropic properties. For both membrane systems, the effects observed with Hg(NO3)2 were greater than those with HgCl2, which can be accounted for by the absence of competition with chloride ions in samples containing Hg(NO3)2.[Cl-] governs the availability of Hg(II) by determining its chemical speciation: increasing [Cl-] generates HgCl3- and HgCl4(2-), which do not interact with lipid binding sites. These results indicate that besides protein thiol groups, Hg(II)-lipid binding sites play an important role in the interaction of Hg(II) with red cell membranes that is qualitatively different from Hg(II) binding to protein thiol groups.
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Affiliation(s)
- M Delnomdedieu
- Health Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711
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Delnomdedieu M, Boudou A, Georgescauld D, Dufourc EJ. Specific interactions of mercury chloride with membranes and other ligands as revealed by mercury-NMR. Chem Biol Interact 1992; 81:243-69. [PMID: 1540995 DOI: 10.1016/0009-2797(92)90081-u] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
High resolution mercury nuclear magnetic resonance (199Hg-NMR) experiments have been performed in order to monitor mercury chemical speciation when HgCl2 is added to water solutions and follow mercury binding properties towards biomembranes or other ligands. Variations of 199Hg chemical shifts by several hundred ppm depending upon pH and/or pCl changes or upon ligand or membrane addition afforded to determine the thermodynamic parameters which describe the equilibria between the various species in solution. By comparison to an external reference, the decrease in concentration of mercury species in solution allowed to estimate the amount as well as the thermodynamic parameters of unlabile mercury-ligand or mercury-membrane complexes. Hence, some buffer molecules can be classified in a scale of increasing complexing power towards Hg(II): EGTA greater than Tris greater than HEPES. In contrast, MOPS, Borax, phosphates and acetates show little complexation properties for mercury, in our experimental conditions. Evidence for complexation with phosphatidylethanolamine (PE), phosphatidylserine (PS) and human erythrocyte membranes has been found. Hg(II) does not form complexes with egg phosphatidylcholine membranes. Interaction with PE and PS model membranes can be described by the presence of two mercury sites, one labile, the other unlabile, in the NMR time scale. In the labile site Hg(PE) and Hg(PS)2 would be formed whereas in the unlabile site Hg(II) would establish bridges between three PE or PS molecules. Calculated thermodynamic data clearly indicate that PE is a better complexing agent than PS. Evidence is also found that complexation with lipids uses at first the HgCl2 species. Interestingly, mercury complexation with ligands or membranes can be completely reversed by addition of decimolar NaCl solutions. Minute mechanisms for mercury complexation with the primary amine of PE or PS membrane head groups are discussed.
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Saouter E, Ribeyre F, Boudou A, Maury-Brachet R. Hexagenia rigida (ephemeroptera) as a biological model in aquatic ecotoxicology: experimental studies on mercury transfers from sediment. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 1991; 69:51-67. [PMID: 15092170 DOI: 10.1016/0269-7491(91)90163-q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/1990] [Revised: 07/30/1990] [Accepted: 08/07/1990] [Indexed: 05/24/2023]
Abstract
The accumulation of two mercury compounds--HgCl(2) and CH(3)HgCl--by Hexagenia rigida (burrowing mayfly nymphs) from contaminated sediments was investigated experimentally. Three exposure periods were selected: 7, 14 and 28 days. Results reveal a high capacity of this species for Hg accumulation and considerable differences between the two chemical forms of the metal. Thus, the amount of total mercury accumulated after 28 days' exposure would be 60 times greater for the organic form if the two compounds were initially added to the sediment in the same concentrations. No significant growth inhibition appears for the different experimental conditions studied. Data treatment at the organism level showed a positive linear correlation between the fresh weight and Hg content in the nymphs; this was especially marked when the exposure time was relatively long and Hg was in the form of CH(3)HgCl. The study of mercury distribution in the organs of Hexagenia rigida (gills and gut) and the examination of results obtained in similar experimental conditions after contamination of the nymphs via the water column showed the importance of the trophic route, via ingested sediment, for the bioaccumulation of the metal initially introduced into the sediment.
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Affiliation(s)
- E Saouter
- Laboratoire d'Ecologie fondamentale et Ecotoxicologie, URA CNRS 1356, Université de Bordeaux I, UFR de Biologie, Avenue des facultés, 33405 Talence Cedex, France
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Saouter E, Le Menn R, Boudou A, Ribeyre F. Structural and ultrastructural analysis of gills and gut of Hexagenia rigida nymphs (ephemeroptera) in relation to contamination mechanisms. Tissue Cell 1991; 23:929-38. [DOI: 10.1016/0040-8166(91)90042-r] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/1991] [Revised: 07/04/1991] [Indexed: 11/24/2022]
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