Comparative Effects of Deferiprone and Salinomycin on Lead-Induced Disturbance in the Homeostasis of Intrarenal Essential Elements in Mice

Lead (Pb) exposure induces severe nephrotoxic effects in humans and animals. Herein, we compare the effects of two chelating agents, salinomycin and deferiprone, on Pb-induced renal alterations in mice and in the homeostasis of essential elements. Adult male mice (Institute of Cancer Research (ICR)) were randomized into four groups: control (Ctrl)—untreated mice administered distilled water for 28 days; Pb-exposed group (Pb)—mice administered orally an average daily dose of 80 mg/kg body weight (BW) lead (II) nitrate (Pb(NO₃)₂) during the first two weeks of the experimental protocol followed by the administration of distilled water for another two weeks; salinomycin-treated (Pb + Sal) group—Pb-exposed mice, administered an average daily dose of 16 mg/kg BW salinomycin for two weeks; deferiprone-treated (Pb + Def) group—Pb-exposed mice, administered an average daily dose of 20 mg/kg BW deferiprone for 14 days. The exposure of mice to Pb induced significant accumulation of the toxic metal in the kidneys and elicited inflammation with leukocyte infiltrations near the glomerulus. Biochemical analysis of the sera revealed that Pb significantly altered the renal function markers. Pb-induced renal toxicity was accompanied by a significant decrease in the endogenous renal concentrations of phosphorous (P), calcium (Ca), copper (Cu) and selenium (Se). In contrast to deferiprone, salinomycin significantly improved renal morphology in Pb-treated mice and decreased the Pb content by 13.62% compared to the Pb-exposed group. There was also a mild decrease in the renal endogenous concentration of magnesium (Mg) and elevation of the renal concentration of iron (Fe) in the salinomycin-treated group compared to controls. Overall, the results demonstrated that salinomycin is a more effective chelating agent for the treatment of Pb-induced alterations in renal morphology compared to deferiprone.     

Pb Stress and Ectomycorrhizas: Strong Protective Proteomic Responses in Poplar Roots Inoculated with Paxillus involutus Isolate and Characterized by Low Root Colonization Intensity

The commonly observed increased heavy metal tolerance of ectomycorrhized plants is usually linked with the protective role of the fungal hyphae covering colonized plant root tips. However, the molecular tolerance mechanisms in heavy metal stressed low-colonized ectormyocrrhizal plants characterized by an ectomycorrhiza-triggered increases in growth are unknown. Here, we examined Populus × canescens microcuttings inoculated with the Paxillus involutus isolate, which triggered an increase in poplar growth despite successful colonization of only 1.9% ± 0.8 of root tips. The analyzed plants, lacking a mantle—a protective fungal biofilter—were grown for 6 weeks in agar medium enriched with 0.75 mM Pb(NO₃)₂. In minimally colonized ‘bare’ roots, the proteome response to Pb was similar to that in noninoculated plants (e.g., higher abundances of PM- and V-type H⁺ ATPases and lower abundance of ribosomal proteins). However, the more intensive activation of molecular processes leading to Pb sequestration or redirection of the root metabolic flux into amino acid and Pb chelate (phenolics and citrate) biosynthesis coexisted with lower Pb uptake compared to that in controls. The molecular Pb response of inoculated roots was more intense and effective than that of noninoculated roots in poplars.     

Adsorption of heavy metal cations from aqueous solutions by wool fibers

Adsorption of metal cations by kivircik wool from aqueous NiCl₂, CuCl₂, ZnCl₂, CdCl₂, HgCl₂ and Pb(NO₃)₂ solutions at 25°C and 50°C was investigated using atomic absorption spectroscopy. A fiber diffusion controlled adsorption rate model was used to predict the effective diffusion coefficients of metal ions in wool. It has been shown that wool is a potential adsorbent for removing toxic metal ions from contaminated water.     

Spermatozoa Transcriptional Response and Alterations in PL Proteins Properties after Exposure of Mytilus galloprovincialis to Mercury

Mercury (Hg) is an environmental pollutant that impacts human and ecosystem health. In our previous works, we reported alterations in the properties of Mytilus galloprovincialis protamine-like (PL) proteins after 24 h of exposure to subtoxic doses of toxic metals such as copper and cadmium. The present work aims to assess the effects of 24 h of exposure to 1, 10, and 100 pM HgCl₂ on spermatozoa and PL proteins of Mytilus galloprovincialis. Inductively coupled plasma–mass spectrometry indicated accumulation of this metal in the gonads of exposed mussels. Further, RT-qPCR analyses showed altered expression levels of spermatozoa mt10 and hsp70 genes. In Mytilus galloprovincialis, PL proteins represent the major basic component of sperm chromatin. These proteins, following exposure of mussels to HgCl₂, appeared, by SDS-PAGE, partly as aggregates and showed a decreased DNA-binding capacity that rendered them unable to prevent DNA damage, in the presence of CuCl₂ and H₂O₂. These results demonstrate that even these doses of HgCl₂ exposure could affect the properties of PL proteins and result in adverse effects on the reproductive system of this organism. These analyses could be useful in developing rapid and efficient chromatin-based genotoxicity assays for pollution biomonitoring programs.     

A Smart Nanotherapeutic Agent for in vitro and in vivo Reversal of Heavy-Metal-Induced Causality: Key Information from Optical Spectroscopy

Human exposure to heavy metals can cause a variety of life-threatening disorders, affecting almost every organ of the body, including the nervous, circulatory, cardiac, excretory, and hepatic systems. The presence of heavy metal (cause) and induced oxidative stress (effect) are both responsible for the observed toxic effects. The conventional and effective way to combat heavy metal overload diseases is through use of metal chelators. However, they possess several side effects and most importantly they fail to manage the entire causality. In this study, we introduce citrate-functionalized Mn₃O₄ nanoparticles (C−Mn₃O₄ NPs) as an efficient chelating agent for treatment of heavy metal overload diseases. By means of UV/Vis absorbance and steady-state fluorescence spectroscopic techniques we investigated the efficacy of the NPs in chelation of a model heavy metal, lead (Pb). We also explored the retention of antioxidant properties of the Pb-chelated C−Mn₃O₄ NPs using a UV/Vis-assisted DPPH assay. Through CD spectroscopic studies we established that the NPs can reverse the Pb-induced structural modifications of biological macromolecules. We also studied the in vivo efficacy of NPs in Pb-intoxicated C57BL/6j mice. The NPs were not only able to mobilize the Pb from various organs through chelation, but also saved the organs from oxidative damage. Thus, the C−Mn₃O₄ NPs could be an effective nanotherapeutic agent for complete reversal of heavy-metal-induced toxicity through chelation of the heavy metal and healing of the associated oxidative stress.     

A Clearance Period after Soluble Lead Nanoparticle Inhalation Did Not Ameliorate the Negative Effects on Target Tissues Due to Decreased Immune Response

The inhalation of metal (including lead) nanoparticles poses a real health issue to people and animals living in polluted and/or industrial areas. In this study, we exposed mice to lead(II) nitrate nanoparticles [Pb(NO₃)₂ NPs], which represent a highly soluble form of lead, by inhalation. We aimed to uncover the effects of their exposure on individual target organs and to reveal potential variability in the lead clearance. We examined (i) lead biodistribution in target organs using laser ablation and inductively coupled plasma mass spectrometry (LA-ICP-MS) and atomic absorption spectrometry (AAS), (ii) lead effect on histopathological changes and immune cells response in secondary target organs and (iii) the clearance ability of target organs. In the lungs and liver, Pb(NO₃)₂ NP inhalation induced serious structural changes and their damage was present even after a 5-week clearance period despite the lead having been almost completely eliminated from the tissues. The numbers of macrophages significantly decreased after 11-week Pb(NO₃)₂ NP inhalation; conversely, abundance of alpha-smooth muscle actin (α-SMA)-positive cells, which are responsible for augmented collagen production, increased in both tissues. Moreover, the expression of nuclear factor κB (NF-κB) and selected cytokines, such as tumor necrosis factor alpha (TNFα), transforming growth factor beta 1 (TGFβ1), interleukin 6(IL-6), IL-1α and IL-1β , displayed a tissue-specific response to lead exposure. In summary, diminished inflammatory response in tissues after Pb(NO₃)₂ NPs inhalation was associated with prolonged negative effect of lead on tissues, as demonstrated by sustained pathological changes in target organs, even after long clearance period.     

Removal of lead,cadmium and zinc from aqueous solutions by precipitation with sodium Di‐(n‐octyl) phosphinate

Sodium di‐(n‐octyl) phosphinate (NaL) was used as a precipitating agent to remove heavy metals from aqueous nitrate solutions. Cadmium, zinc and mixtures of lead, cadmium and zinc were precipitated in the form of PbL_2(s), CdL_2(s), and ZnL_2(s). Lowering the pH of the feed solution reduced the removal of the metals as some of the phosphinate precipitated in the acid form as HL_(S). The removal of lead, cadmium, and zinc, from a solution containing the three metals gave a selectivity in the order Zn > Pb > Cd. Predictions of an equilibrium‐constant model, using measured solubility products of the precipitates and literature values of stability constants, gave metal removals, loss of precipitating agent, and equilibrium pH in good agreement with measured values.     

Quantitation of Metals During the Extraction of Virgin Olive Oil from Olives Using ICP-MS after Microwave-assisted Acid Digestion

Trace metals such as Cu and Fe have negative effects on the oxidative stability of olive oils, and consequently, their concentrations are used as quality criterion. Also, maximum levels are established for heavy metals (As and Pb) in olive oils due to their high toxicity. Olive fruits can be contaminated with these metals from soil and air and from the use of pesticides or fertilizers, with the potential contamination of virgin olive oil (VOO) during its extraction from the fruits. This work presents two goals: (a) to optimize an analytical method for the determination of metals in raw olive fruits using an Abencor system; (b) to carry out a preliminary study of the fate of the metals during VOO extraction. The selected metals were quantified in raw olive fruits, and in the olive pomace and VOO obtained after their processing. The metal determination was performed by inductively coupled plasma-mass spectrometry after microwave-assisted acid digestion with HNO₃/H₂O₂. The results showed that most of the metals (at least 90 %) present in the olive fruits were retained by the olive pomace, so obtaining high-quality VOO from the point of view of its metal content.     

Solution and solid-state photoluminescence of dinuclear Pb(II) dicarboxylate compound with 2,6-bis(benzimidazolyl)pyridine: The lone-pair stereochemistry and its effect on supramolecular interaction

[Pb₂(boa)(Hbbp)₂] has been synthesized by treating 4-carboxylphenoxyacetic (H₂boa) and 2,6-bis(benzimidazolyl)pyridine (H₂bbp) with metal salts under hydrothermal conditions. Adjacent metal centers forms dinuclear metal complex through carboxylato groups as building blocks. The arrangement of the half deprotonated H₂bbp ligand and carboxylate groups exhibits a coordination gap around the Pb(II) ion, occupied possibly by a stereoactive lone pair of electrons on Pb(II), with the coordination environment around the lead atoms is hemidirected. This system is a particularly clear example that coordination sphere of a unique dinuclear Pb(II) compound was controlled by lone pair activity, weak Pb···O interactions, π–π stacking and the hydrogen bonds. The above weak interactions influence differently strong red-shifted effect about the solution and solid-state photoluminescence of the compound, compared to the free ligand.     

Neurotoxicity of Chronic Co-Exposure of Lead and Ionic Liquid in Common Carp: Synergistic or Antagonistic?

Previous studies have indicated that the harmful heavy metal lead (Pb) contamination in aquatic systems has caused intelligence development disorders and nervous system function abnormalities in juveniles due to the increased permeability of the blood–brain barrier. Ionic liquids (ILs) are considered “green” organic solvents that can replace traditional organic solvents. Studies have found the presence of ILs in soil and water due to chemical applications or unintentional leakage. Therefore, what would happen if Pb interacted with ILs in a body of water? Could ILs enable Pb to more easily cross the blood–brain barrier? Therefore, we examined the combined exposure of Pb and ILs in common carp at low concentration (18.3 mg L⁻¹ of Pb(CH₃COO)₂•3 H₂O and 11 mg L⁻¹ of the IL 1-methyl-3-octylimidazolium chloride, 5% of their LC₅₀) for 28 days in the present study. The result of a neurobehavioral assay showed that chronic exposure of lead at lower concentrations significantly altered fish movement and neurobehaviors, indicating that lead exposure caused neurotoxicity in the carp. Increases in the neurotransmitter dopamine levels and injuries in the fish brain accounted for neurobehavioral abnormalities induced by lead exposure. Moreover, we also found that lead could easily cross the blood–brain barrier and caused significant bioaccumulation in the brain. Particularly, our study indicated that the ionic liquid could not synergistically promote blood–brain barrier permeability and hence failed to increase the absorption of lead in the fish brain, suggesting that the combined exposure of lead and ILs was not a synergistic effect but antagonism to the neurotoxicity. The results of this study suggested that ILs could recede the Pb induced neurotoxicity in fish.     

Synthesis, structure and magnetic properties of a novel lead(II) complex containing nitronyl nitroxide radicals

The lead(II) complex with nitronyl nitroxide, [Pb(NIT2Py)₂(NO₃)₂] [NIT2Py = 2-(2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide], has been prepared and characterized by magnetic and single-crystal X-ray diffraction studies. In the complex, the lead(II) ion is coordinated with two bidentate nitronyl nitroxide and two nitrate anions. The lead(II) ion shows seven-coordinate geometry. Magnetic susceptibility data for the title complex has been measured in the range 5–300 K. There are antiferromagnetic interaction between the coordinated nitronyl nitroxides (J = −19.35 cm⁻¹) and intermolecular ferromagnetic interactions. Thus, we observe the sixth periodic IVA group metal element Pb(II) ion providing an effective pathway for the magnetic exchange interaction between nitronyl nitroxide radicals.     

Exopolysaccharide Carbohydrate Structure and Biofilm Formation by Rhizobium leguminosarum bv. trifolii Strains Inhabiting Nodules of Trifolium repens Growing on an Old Zn–Pb–Cd-Polluted Waste Heap Area

Heavy metals polluting the 100-year-old waste heap in Bolesław (Poland) are acting as a natural selection factor and may contribute to adaptations of organisms living in this area, including Trifolium repens and its root nodule microsymbionts—rhizobia. Exopolysaccharides (EPS), exuded extracellularly and associated with bacterial cell walls, possess variable structures depending on environmental conditions; they can bind metals and are involved in biofilm formation. In order to examine the effects of long-term exposure to metal pollution on EPS structure and biofilm formation of rhizobia, Rhizobium leguminosarum bv. trifolii strains originating from the waste heap area and a non-polluted reference site were investigated for the characteristics of the sugar fraction of their EPS using gas chromatography mass-spectrometry and also for biofilm formation and structural characteristics using confocal laser scanning microscopy under control conditions as well as when exposed to toxic concentrations of zinc, lead, and cadmium. Significant differences in EPS structure, biofilm thickness, and ratio of living/dead bacteria in the biofilm were found between strains originating from the waste heap and from the reference site, both without exposure to metals and under metal exposure. Received results indicate that studied rhizobia can be assumed as potentially useful in remediation processes.     

Surface Electrical Potentials of Root Cell Plasma Membranes: Implications for Ion Interactions,Rhizotoxicity, and Uptake

Many crop plants are exposed to heavy metals and other metals that may intoxicate the crop plants themselves or consumers of the plants. The rhizotoxicity of heavy metals is influenced strongly by the root cell plasma membrane (PM) surface’s electrical potential (ψ₀). The usually negative ψ₀ is created by negatively charged constituents of the PM. Cations in the rooting medium are attracted to the PM surface and anions are repelled. Addition of ameliorating cations (e.g., Ca²⁺ and Mg²⁺) to the rooting medium reduces the effectiveness of cationic toxicants (e.g., Cu²⁺ and Pb²⁺) and increases the effectiveness of anionic toxicants (e.g., SeO₄²⁻ and H₂AsO₄⁻). Root growth responses to ions are better correlated with ion activities at PM surfaces ({I^Z}₀) than with activities in the bulk-phase medium ({I^Z}_b) (I^Z denotes an ion with charge Z). Therefore, electrostatic effects play a role in heavy metal toxicity that may exceed the role of site-specific competition between toxicants and ameliorants. Furthermore, ψ₀ controls the transport of ions across the PM by influencing both {I^Z}₀ and the electrical potential difference across the PM from the outer surface to the inner surface (E_m,surf). E_m,surf is a component of the driving force for ion fluxes across the PM and controls ion-channel voltage gating. Incorporation of {I^Z}₀ and E_m,surf into quantitative models for root metal toxicity and uptake improves risk assessments of toxic metals in the environment. These risk assessments will improve further with future research on the application of electrostatic theory to heavy metal phytotoxicity in natural soils and aquatic environments.     

Stability and wettability of ternary carbide Mo2Ga2C in molten metals

Mo₂Ga₂C is a novel member of MAX phases, which is a family of ternary carbide/nitride with layered structure. The stability and wettability of Mo₂Ga₂C in molten metals are crucial for the application of Mo₂Ga₂C in the field of composite materials. In this work, the stability and wettability of Mo₂Ga₂C in three molten metals (Pb, Sn and Zn) were investigated. Mo₂Ga₂C was mixed with metal powders and annealed at different temperatures under vacuum. At 700 °C, Mo₂Ga₂C was not stable in any of the three molten metals. The decomposition of Mo₂Ga₂C was affected by the type of metal matrix as well as the reaction temperature. Mo₂Ga₂C decomposed at 550 °C in Pb, at 450 °C in Sn, or at 650 °C–750 °C in Zn. To characterized the wettability of these metals with Mo₂Ga₂C, the contact angle of molten metals with Mo₂Ga₂C at 650 °C were measured, which are 103° for Pb, 126° for Sn and 0° for Zn, respectively. Mo₂Ga₂C has good wettability with Zn and is not wetted by Pb and Sn.     

Experimental phase equilibria study and thermodynamic modelling of the PbO-“FeO”-SiO2-ZnO,PbO-“FeO”-SiO2-Al2O3 and PbO-“FeO”-SiO2-MgO systems in equilibrium with metallic Pb and Fe

Phase equilibria of the PbO-“FeO”-SiO₂-ZnO, PbO-“FeO”-SiO₂-Al₂O₃ and PbO-“FeO”-SiO₂-MgO slags with liquid Pb metal, solid or liquid Fe metal and solid oxides (cristobalite and tridymite SiO₂, willemite (Zn,Fe)₂SiO₄, wustite (Fe,Al)O_1+x, spinel (Fe,Al)₃O₄, olivine Fe₂SiO₄, corundum (Al,Fe)₂O₃, mullite Al₆Si₂O₁₃ and pyroxene (Mg,Fe)SiO₃) were investigated at 1125–1670 °C. These conditions correspond to the minimum solubility of PbO in slag in presence of Pb and Fe metals at reducing conditions and represent the limit of lead smelting and slag cleaning process. High-temperature equilibration on silica, corundum or iron foil substrates, followed by quenching and direct measurement of Pb, Fe, Si, Zn, Al and Mg concentrations in the liquid and solid phases with the electron probe X-ray microanalysis (EPMA) was used. Present data can be used to improve the thermodynamic models for all phases in this system.     

Potential of carbon nanomaterials for removal of heavy metals from water

Heavy metals, such as, cadmium, lead, nickel and zinc can be removed from water using sorbents. The rate and extent of removal may be enhanced by choice of appropriate sorbents. In this study heavy metal sorption was studied on indigenously synthesized carbon nanomaterials (CNMs). Two CNMs differing in surface morphology were synthesized using turpentine oil in a chemical vapour deposition (CVD) setup by varying the process parameters. Activation and catalyst removal were achieved by post-treatment with HNO₃ and KOH. Characterization of the CNMs produced revealed that both comprised of graphitic amorphous carbon, however, while the nanocarbon (NC) produced using cobalt catalyst in N₂ atmosphere comprised of varying grain sizes indicative of soot, the nanoporous carbon (NPC) produced using silica catalyst in H₂ atmosphere had a distinctive uniformly porous surface morphology. Comparative sorption studies with cadmium, lead, nickel and zinc also revealed greater sorption on NPC compared to NC. Batch isotherms for the various heavy metals using NPC and a commercial activated carbon (AC) widely used for metal sorption revealed that NPC is characterized by significantly higher metal sorption capacity and more favourable sorption energetics. The superior performance of NPC as a sorbent may be due to its unique nanoporous structure.     

First-principles study on transition metal-doped anatase TiO2

The electronic structures, formation energies, and band edge positions of anatase TiO₂ doped with transition metals have been analyzed by ab initio band calculations based on the density functional theory with the planewave ultrasoft pseudopotential method. The model structures of transition metal-doped TiO₂ were constructed by using the 24-atom 2 × 1 × 1 supercell of anatase TiO₂ with one Ti atom replaced by a transition metal atom. The results indicate that most transition metal doping can narrow the band gap of TiO₂, lead to the improvement in the photoreactivity of TiO₂, and simultaneously maintain strong redox potential. Under O-rich growth condition, the preparation of Co-, Cr-, and Ni-doped TiO₂ becomes relatively easy in the experiment due to their negative impurity formation energies, which suggests that these doping systems are easy to obtain and with good stability. The theoretical calculations could provide meaningful guides to develop more active photocatalysts with visible light response.     

Solidification/Stabilization of Heavy Metal-Loaded Red Muds and Fly Ashes

Red muds and fly ashes, used as immobilization agents for heavy metal ions in aqueous solution, were loaded to saturation with Pb(II), Cd(II) and Cu(II), and solidified by cement-based CFS technology to hard concrete blocks which should not pose any risk to the environment. The setting and hardening characteristics of mortars as well as the flexural and mechanical strengths of the solidified specimens were optimized with respect to the dosage of natural and metal-loaded solid wastes. The fixed metals essentially did not leach out into water over extended periods. The matrix-disrupting effect of lead was eliminated by adding NaAlO₂, Ca₃(PO₄)₂ or Ca₃(PO₄)₂+CaCl₂ at optimal dosages so as to improve the setting, hardening and mechanical properties of the final concrete block. © 1997 SCI.