Effects Of Thallium Research Articles

Effects of Thallium–Aluminum‐Codoped Zinc Oxide Thin Film as a New Transparent Conducting Oxide

Herein, the electro–optical properties of sol–gel spin‐coated “thallium–aluminum‐codoped zinc oxide (TAZO)” focusing on the effects of thallium are investigated. It is shown that the amount of thallium (Tl) has a significant effect on improving the electrical properties of TAZO as a new transparent conducting oxide (TCO). The optimum results are achieved by adding 1 at% of Tl to aluminum‐doped zinc oxide (AZO), after which the sheet resistance (Rs) value is reduced from 30.21 to 2.832 KΩ sq−1. Although less Rs is recorded in all amounts of Tl used (from 1 to 4 at%) than in Tl‐free samples, Rs also increases as the amount of Tl increases, which is related to the degradation of the crystal structure at higher values of Tl. In view of a trade‐off between electrical conductivity and optical transparency, a decrease in transparency in the presence of Tl is a predictable issue, but while the Tl‐free samples record 90% transparency, the uniform thin film of 1 at% Tl‐AZO is able to achieve 85% transparency. This small amount of reduction in transparency shows the high potential of Tl to improve the properties of AZO as a TCO.

The Effects of Thallium on the Spontaneous Contraction of the Heart Muscle and the Energetic Processes in Cardiomyocyte Mitochondria

The Effects of Thallium on the Spontaneous Contraction of the Heart Muscle and the Energetic Processes in Cardiomyocyte Mitochondria

Assessing the fate and toxicity of Thallium I and Thallium III to three aquatic organisms

Thallium has been shown to significantly increase in both water and aquatic biota after exposure to metal mine effluent, however, there is a lack of knowledge as to its fate and effect in the aquatic environment. The objectives of this project were to assess (1) fate of thallium by conducting speciation analysis and determining the influence of water quality on toxicity and (2) effects of thallium (I) and (III) on three aquatic species; the algae, Pseudokirchneriella subcapitata, the invertebrate Ceriodaphnia dubia and the vertebrate Pimephales promelas.Speciation analysis proved challenging with poor recovery of thallium (I), however analysis with solutions >125μg/L revealed that over a 7-d period, recovery of thallium (III) was less than 15%, suggesting that the majority of thallium (III) was converted to Thallium (I). It was only in fresh solutions where recovery of Thallium (III) was greater than 80%.The lowest IC25s generated during our effects assessment for both Thallium (I) and (III) were more than 10-fold greater than the highest concentration recorded in receiving environments (8μg/L) and more than 100-fold greater than the current guideline (0.8μg/L).To assess the influence of water quality on thallium toxicity, the concentrations of both potassium and calcium were reduced in dilution water. When potassium was reduced for both C. dubia and P. subcapitata tests, the lowest IC25 generated was 5-fold higher than the current guideline, but within the range of concentrations reported in receiving environments for both Thallium (I) and (III). When calcium was reduced in dilution water, toxicity only increased in the Tl (III) tests with C. dubia; the IC25 for Tl(III), similar to the exposures conducted with reduced potassium, was within the range of total thallium concentrations reported in the receiving environment.Without an accurate, repeatable method to assess thallium speciation at low concentrations it is not possible to draw any firm conclusions as to whether the IC25s for Tl (III) are relevant to concentrations present in receiving environments. Based on the results of our study we recommend that any test, to determine Thallium (III) toxicity, use fresh solutions, made daily, to get good recovery and accurate toxicity results. The results generated in our effects and exposure assessment would indicate that the current guideline of 0.8μg/L is protective. Special attention should be placed on the concentration of potassium in receiving environments when estimating thallium toxicity.

Tl(I) and Tl(III) alter the expression of EGF-dependent signals and cyclins required for pheochromocytoma (PC12) cell-cycle resumption and progression.

The effects of thallium [Tl(I) and Tl(III)] on the PC12 cell cycle were evaluated without (EGF(-)) or with (EGF(+)) media supplementation with epidermal growth factor (EGF). The following markers of cell-cycle phases were analyzed: cyclin D1 (G1 ); E2F-1, cyclin E and cytosolic p21 (G1 →S transition); nuclear PCNA and cyclin A (S); and cyclin B1 (G2). The amount of cells in each phase and the activation of the signaling cascade triggered by EGF were also analyzed. Tl(I) and Tl(III) (5-100 μM) caused dissimilar effects on PC12 cell proliferation. In EGF(-) cells, Tl(I) increased the expression of G1 →S transition markers and nuclear PCNA, without affecting cyclin A or cyclin B1. In addition to those, cyclin B1 was also increased in EGF(+) cells. In EGF(-) cells, Tl(III) increased the expression of cyclin D1, all the G1→S and S phase markers and cyclin B1. In EGF(+) cells, Tl(III) increased cyclin D1 expression and decreased all the markers of G1 →S transition and the S phase. Even when these cations did not induce the activation of EGF receptor (EGFR) in EGF(-) cells, they promoted the phosphorylation of ERK1/2 and Akt. In the presence of EGF, the cations anticipated EGFR phosphorylation without affecting the kinetics of EGF-dependent ERK1/2 and Akt phosphorylation. Altogether, results indicate that Tl(I) promoted cell proliferation in both EGF(-) and EGF(+) cells. In contrast, Tl(III) promoted the proliferation of EGF(-) cells but delayed it in EGF(+) cells, which may be related to the toxic effects of this cation in PC12 cells.

Toxicity of thallium on isolated rat liver mitochondria: The role of oxidative stress and MPT pore opening

Thallium(I) is a highly toxic heavy metal; however, up to now, its mechanisms are poorly understood. The authors' previous studies showed that this compound could induce reactive oxygen species (ROS) formation, reduced glutathione (GSH) oxidation, membrane lipid peroxidation, and mitochondrial membrane potential (MMP) collapse in isolated rat hepatocyte. Because the liver is the storage site of thallium, it seems that the liver mitochondria are one of the important targets for hepatotoxicity. In this investigation, the effects of thallium on mitochondria were studied to investigate its mechanisms of toxicity. Mitochondria were isolated from rat liver and incubated with different concentrations of thallium (25-200 µM). Thallium(I)-treated mitochondria showed a marked elevation in oxidative stress parameters accompanied by MMP collapse when compared with the control group. These results showed that different concentrations of thallium (25-200 µM) induced a significant (P < 0.05) increase in mitochondrial ROS formation, ATP depletion, GSH oxidation, mitochondrial outer membrane rupture, mitochondrial swelling, MMP collapse, and cytochrome c release. In general, these data strongly supported that the thallium(I)-induced liver toxicity is a result of the disruptive effect of this metal on the mitochondrial respiratory complexes (I, II, and IV), which are the obvious causes of metal-induced ROS formation and ATP depletion. The latter two events, in turn, trigger cell death signaling via opening of mitochondrial permeability transition pore and cytochrome c expulsion.

The Effects of Thallium Acetate on Hepatopancreatic Cells of Gammarus pulex (Crustacea: Amphipoda)

In our study, the toxic effects of thallium on Gammarus pulex a sensitive indicator organism for environmental pollution was studied for cytological changes. According to studies carried out with thallium acetate, this chemical was observed to lead to cellular changes in the hepatopancreas of the Gammarus pulex. In our studies, by using EPA acute toxicity tests, the LC 50 value was found to be 0.244 mg/L. The LC 50 value was calculated using the EPA Probit Analysis Program. The cytological changes to Gammarus pulex when exposed to thallium was examined with the Transmission Electron Microscope. Due to thallium intoxication, degenerative changes were frequently present in the cellular membranes; there were changes in the mitochondria as partial or total loss of cristae, there was an increase in the number of lipid droplets, lysosomes and autophagic vacuoles were found to have increased in the hepatocytesand the nucleus showed significant shrinkage and deformation. We also observed fragmentation and dilation of the rough endoplasmic reticulum (RER) and the number of lesions also increased in the inner and outer mitochondrial membranes and in the RER. A lot of lipid droplets were also observed in the hepatocytes.

ChemInform Abstract: The Kinetics of the Soft Metal Ion Promoted Hydrolysis of Phenyl Isothiocyanates in Aqueous Solution. The Effects of Thallium(III) Ions and of Substituents

In the Hg2+ ion-promoted hydrolysis of RC6H4NCS a large increase in electron-release by R produces only a small increase in reaction rate. These substituent effects support the mechanism previously proposed. Tl3+ ions are surprisingly much (ca. 103-fold) less effective in promoting the hydrolyses than are Hg2+ ions, but show the same kinetic form and similar substituent effects. A similar mechanism is suggested. The low reactivity of Tl3+ ions, the different pattern of their activation parameters, and the greater dependence of the Tl3+ ion-promotion on ionic strength, all suggest that these ions form adducts with isothiocyanates with special difficulty; the comparable reactivity normally found for Hg2+ and Tl3+ ions when promoting the decomposition of organosulphur compounds may require chelating substrates.

Determination of atenolol by the micelle‐stabilized room‐temperature phosphorescence methodology

A micellar-stabilized room-temperature phosphorescence (MS-RTP) method for the determination of atenolol has been developed in micellar solutions of sodium dodecylsulphate (SDS) in the presence of thallium(I) as a heavy atom and sodium sulphite as an oxygen scavenger. The effects of thallium(I) nitrate, SDS and sodium sulphite concentrations on atenolol MS-RTP intensity were studied. Optimized conditions to obtain maximum sensitivity were 0.015 mol/L thallium(I) nitrate, 0.1 mol/L SDS and 0.0075 mol/L sodium sulphite. The maximum phosphorescence signal was completely developed in 10 min and the intensity was measured at lambda(ex) = 272 nm and lambda(em) = 412 nm. The linear range of application obtained was 2.01-16.00 microg/mL. The detection limit estimated from the least-squares regression analysis was 0.86 microg/mL and the relative standard deviation of 10 replicates was 1.7%. The proposed method was applied to the determination of atenolol in a pharmaceutical formulation. The quantitation was carried out by means of standard calibration, standard-additions calibration and Youden calibration. These three experiments were necessary to evaluate the presence of constant and proportional errors due to the matrix.

Alteration of the doping state induced by thallium loss in Tl-2201

Influence of thallium content in Tl-2201 on superconductivity is investigated by annealing at different temperatures at 0.2 oxygen pressure. Deeply overdoped, non-superconducting Tl-2201s undergo a transition from non-superconducting to superconducting and then to non-superconducting state with increasing annealing temperature. By analysis of mass loss of Tl-2201 at high temperature, effects of thallium and oxygen content on superconductivity were separated. The loss of thallium results in that the Tl-2201 undergoes an alteration from over-doping to under-doping state. During annealing at temperatures lower than 500 °C, the thallium lose is ignored. The mainly feature of Tl-2201 exhibits absorption of oxygen and an increase in the mass of Tl-2201. At temperatures higher than 500 °C, the loss of thallium in Tl-2201 becomes dominant, meantime accompanying with a release of oxygen. A phase diagraph with respect to the relationship between the hole carrier concentration, the interstitial oxygen and the substitution Cu 2+ for Tl 3+ was discussed. The under-doped Tl-2201s only appear at low substitution Cu 2+ for Tl 3+ region.

Effects of thallium(I) and thallium(III) on liposome membrane physical properties

The hypothesis that thallium (Tl) interaction with membrane phospholipids could result in the alteration of membrane physical properties was investigated. Working with liposomes composed of brain phosphatidylcholine and phosphatidylserine, we found that Tl +, Tl 3+, and Tl(OH) 3 (0.5–25 μM): (a) increased membrane surface potential, (b) decreased the fluidity of the anionic regions of the membrane, in association with an increased fluidity in the cationic regions, and (c) promoted the rearrangement of lipids through lateral phase separation. The magnitude of these effects followed the order Tl 3+, Tl(OH) 3>Tl +. In addition, Tl 3+ also decreased the hydration of phospholipid polar headgroups and induced membrane permeabilization. The present results show that Tl interacts with membranes inducing major alterations in the rheology of the bilayer, which could be partially responsible for the neurotoxic effects of this metal.

Thallium in terrestrial environments--occurrence and effects.

In this investigation thallium contents in soil and plants in the EuroRegion Neisse were analysed and the distribution determined. The median top-soil content is 0.5 mg/kg in the area investigated. In this low-contaminated area the moss Pleurozium schreberi contains 0.04-0.13 microg/g and the moss Polytrichumformosum between 0.01 and 0.05 microg/g Tl. The effects of thallium on man and the terrestrial environment were examined. In an epidemiological study a significant positive correlation was found between the thallium content of the two mosses and the incidence of diseases of the circulatory system. The LOEC for thallium in bioassays with terrestrial invertebrates and plants in artificial soil ranged from 1 to 500 mg/kg, which indicates an toxicity of thallium up to 100 times higher than that of Cadmium.

Effects of Thallium in Soil on the Growth and Thallium Content of Komatsuna (Brassica campestris L.)

Effects of Thallium in Soil on the Growth and Thallium Content of Komatsuna (Brassica campestris L.)

Effects of Thallium in Water Culture Solution on the Growth, and the Thallium Content of 3 Kinds of Seedlings

Effects of Thallium in Water Culture Solution on the Growth, and the Thallium Content of 3 Kinds of Seedlings

Effects of thallium on primary cultures of testicular cells.

The objective of this in vitro study was to examine the response of mixed cultures of Sertoli and germ cells to treatment with thallium (Tl) at the range of concentrations that, in previous studies, was shown in vivo to affect reproduction. Cultures were prepared from the testis of Sprague-Dawley rats. Cultures containing approximately 3.75 x 10(6) cells/ml were treated with Tl concentrations corresponding to 35, 7, and 1.4 micrograms Tl/g testis, estimated from protein content of cultures. Observations at 24, 48, and 72 h after treatment showed a significant release of germ cells into the culture medium that was both concentration and time dependent. Cultures treated with 35 micrograms Tl/g testis showed a threefold increase in germ-cell detachment compared with controls after only 24 h of exposure. As the treatment time increased to 48 h of exposure, even cultures exposed at the lowest Tl concentration (1.4 micrograms Tl/g testis) showed significant loss of germ cells. After 48 h, cultures exposed to 7 micrograms Tl/g testis exhibited a 2.5-fold increase in germ-cell detachment, and those exposed to 35 micrograms Tl/g testis exhibited a 10-fold increase over controls. Morphological investigations of cell cultures showed evident loss of germ cells with significant reduction in prepachytene and pachytene spermatocytes and changes in the shape of Sertoli cells. These results are in agreement with in vivo studies, in which thallium treatment at comparable exposure levels manifested its earliest toxic testicular effects in Sertoli and germ cells. They also demonstrate the usefulness of this in vitro culture technique to assess toxic testicular damage rapidly.

The kinetics of the soft metal ion promoted hydrolysis of phenyl isothiocyanates in aqueous solution. The effects of thallium(III) ions and of substituents

In the Hg2+ ion-promoted hydrolysis of RC6H4NCS a large increase in electron-release by R produces only a small increase in reaction rate. These substituent effects support the mechanism previously proposed. Tl3+ ions are surprisingly much (ca. 103-fold) less effective in promoting the hydrolyses than are Hg2+ ions, but show the same kinetic form and similar substituent effects. A similar mechanism is suggested. The low reactivity of Tl3+ ions, the different pattern of their activation parameters, and the greater dependence of the Tl3+ ion-promotion on ionic strength, all suggest that these ions form adducts with isothiocyanates with special difficulty; the comparable reactivity normally found for Hg2+ and Tl3+ ions when promoting the decomposition of organosulphur compounds may require chelating substrates.

インピーダンス測定法によるパラジウムの電析反応におよぼすタリウムの影響

The effects of thallium on palladium electrodeposition reactions were investigated by impedance measurements. Ethylenediamine in the electrolyte formde an adsorption layer on the electrode surface and lowered the double layer capacitance Cd. However thallium ion in the electrolyte was deposited on the electrode surface at underpotential deposited, breaking the ethylenediamine adsorption layer and increasing Cd. In addition, the addition of thallium ion to the electrolyte resulted in secondary capacitive loops and inductive loops were observed at low frequency. The secondary loops reflected the activation of a crystal growth reaction with increasing overpotential, but the inductive loops did not correspond to the growth mode of the electrodeposits. These responses suggest that the hydrogen ion adsorption reaction as the rate determining step.

Effects of thallium on membrane currents at diastolic potentials in canine cardiac Purkinje strands.

A two-micro-electrode voltage-clamp technique was used to record membrane currents from canine cardiac Purkinje strands during hyperpolarizing steps to potentials between -70 and -150 mV in Tyrode solutions containing K+ and/or Tl+. Complete replacement of external K+ by equimolar Tl+ increases the instantaneous inwardly rectifying current. The inwardly rectifying region of the instantaneous I-V relation is shifted to more positive potentials and its slope is increased. The diastolic time-dependent current is reduced or reversed. Partial substitution of equimolar Tl+ for K+ reduces the diastolic time-dependent current. The instantaneous I-V relation is shifted inward for molar fractions of Tl+ (YTl) greater than 0.5, and is slightly more inward or unchanged for YTl less than or equal to 0.5. Addition of small amounts of Tl+ shifts the instantaneous I-V relation inward and reduces the diastolic time-dependent current. Addition of Tl+ in solutions containing Ba2+ to block the background inward rectifier has no effect on the instantaneous I-V relation; the diastolic time-dependent (pace-maker) current is reduced. Block of the pace-maker current by Tl+ is largely independent of potential in Ba2+ Tyrode solution. Since Tl+ has opposite effects on the pace-maker current and the inward rectifier, these findings support other evidence that the pace-maker current is not part of the background inward rectifier.

Tl+-ions: influence on cardiac contractility.

Attention has recently focussed on the heavy metal thallium as an environmental contaminant of increasing importance. From accidental or suicidal ingestions of thallium it has been known for many years that cardiovascular disorders regularly emerge, and for this reason, a variety of investigations of cardiological interest have been conducted. Amongst these, the effects of thallium on the contractile force of isolated myocardial tissues have been studied. Previous experiments were all carried out at concentrations far beyond those encountered during intoxication and yielded controversal data. We therefore reinvestigated the effects of thallium on myocardial tissue at levels between l0(-8) and 10(-3) M, thus covering the range of thallium concentrations encountered after uptake from a polluted environment through those seen after unintentional or intentional ingestion to levels at which previous studies were performed. Sheep interventricular cordis muscles were used at a stimulation frequency of 0.4 Hz showing three types of responses to thallium exposure. From a total of 32 experiments in 15% of all cases thallium caused a persistent increase in contractility which tended to decrease with time and thallium concentration but always remained greater than the control value. 50% of the experiments showed a progressive loss of contractile force with time and thallium concentration, despite transient increases in contractility which lasted for only 2-5 min after the application of each new thallium concentration. A combination of these types of reaction was observed in the remaining experiments in that a low thallium concentrations myocardial contractility increased considerably but then decreased progressively with time and thallium concentration. Guinea pig papillary muscles were used to test one thallium concentration only for up to 75 min. At 10(-8) M there was no effect, at 10(-7), 10(-6), 10(-5) M Tl+ there were positive inotropic transients followed by an inotropic decay; at 10(-4) M Tl+ only a progressive decrease of contractility was observed. The relationships between time and thallium concentration at different rates of stimulation were examined in two series of experiments at 0.1, 0.2, 0.4, 1.0, and 2.0 Hz. The effects of thallium were accelerated with increased beating rate and the decay of contraction also proceeded to markedly lower levels. In the rested state, thallium was also very effectual; this was illustrated in two series of experiments in which after 10 min intervals of quiescency 15 or more test stimuli were applied at different beating rates (0.1 to 2.0 Hz). The configurations of the resulting staircase phenomena were analyzed with respect to control behavior for each frequency of the test stimuli and for each thallium concentration. These results suggested an involvement of the slow inward current. The steady state values after quiescency showed a pronounced thallium-induced decay similar to that obtained at high constant stimulation rates...

Tl+-ions: effects on the automaticity of sinoatrial tissue and dV/dtmax and iK2 of cardiac Purkinje fibres.

The disrhythmic effects of thallium were investigated in various cardiac tissues to determine the primary site of intoxication with respect to ensuing arrhythmias. In isolated cardiac tissue Lameijer and van Zwieten [1] had contended that arrhythmias arise from the sinus node after thallium poisoning. To test this hypothesis we administered concentrations of Tl+ between 10(-7) and 10(-4) M to guinea pig sinoatrial preparations, to guinea pig papillary muscles and to sheep cardiac Purkinje fibres. In sinoartial preparations thallium provoked increases and decreases of spontaneous beat frequency which were not linked to corresponding changes in contractile force. In conductive tissue, Purkinje fibres, the inactivation kinetics of the fast sodium current and the pacemaker current iK2 were investigated by voltage clamp experiments. Here, thallium was seen to be essentially without toxic effects which could account for arrhythmias. In ventricular muscle actions potentials and contractile force were recorded simultaneously. Here again, ventricular arrhythmias are not to be expected from thallium intoxication in rather high concentrations. The findings support the view that arrhythmogenic effects of thallium are restricted to the sinus node.

Tl+-ions: comparison on the effects on the slow inward current and contractility of ventricular tissues.

To conclude our investigation of thallium effects on cardiac tissues, we studied the slow inward current of sheep cardiac Purkinje fibres exposed to 10-7 to 10-5 ᴍ Tl+ for extended periods of up to 80 min. Our previous results had suggested a possible involvement of the slow inward current during thallium intoxication: a) the modification of contractility staircases observed during thallium exposure, b) action potential recordings of ventricular muscle, c) changes in spontaneous beating in sino-atrial preparations. The thallium levels chosen were between those yielding strong positive inotropic transients and those producing a marked long­term decay of contraction force. The slow inward current was measured using a conventional two-microelectrode-technique and the standard voltage clamp protocol for this current system. The experimental work was restricted to the determination of d∞, the kinetics of activation of the slow inward current and of īsi, the current voltage relation of the current system. This was necessary since the effects of thallium were known to be short-lived and therefore frequent repeat runs of the voltage clamp program had to be performed in order to obtain the time courses of possible transient changes. The results showed that the slow inward current was first increased and then declined at the low concentration of 10-7 ᴍ Tl+. At 10-5 m Tl+ the initial increase was smaller, whereas the decay of the slow inward current proceeded to lower values. Comparison with contractility measure­ments at the same concentrations of thallium showed a distinct parallelism between changes of the slow inward current and myocardial contractility. Despite this apparent relationship, we do not conclude that the contractile events are primarily a result of changes of the slow inward current, since thallium does not seem to specifically alter the parameters of the slow inward current at the membrane level.