Soluble Nickel Research Articles

Time- and concentration-dependent genomic responses of the rat airway to inhaled nickel sulfate.

While insoluble nickel subsulfide (Ni3S2) was carcinogenic in the lung in a 2‐year rat bioassay, soluble nickel sulfate hexahydrate (NiSO4*6H2O) was not. To investigate whether differences in the cellular responses to these two nickel compounds could underlie their differential activities, we conducted parallel studies to determine the gene expression changes in micro‐dissected lung distal airway cells from Fischer 344 rats following inhalation of the two compounds for one and four weeks (6 hr per day, 5 days per week). The results of the Ni3S2 study have been reported previously; this paper reports the results for NiSO4 and provides a comparative analysis. The cellular responses to NiSO4 were highly similar to those previously reported for Ni3S2, and a set of genes was identified whose expression could be used as biomarkers for comparing cellular nickel effects from in vitro or in vivo studies with soluble NiSO4 and particulate Ni3S2. Evaluation of the genomic concentration‐responses for the two compounds suggests that the highest inhaled concentration in the tumor bioassay for NiSO4, which was limited by toxicity, may not have achieved the Ni concentrations at which tumors were observed in the Ni3S2 bioassay. However, several key differences in the immune responses to NiSO4 and Ni3S2 were identified that may result from the differential intracellular disposition of Ni from NiSO4 entering the cell as an ion rather than as a slowly soluble Ni3S2 particle. These differences may also contribute to the observation of tumors in the bioassay for Ni3S2 but not NiSO4. Environ. Mol. Mutagen. 58:607–618, 2017. © 2017 The Authors Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society

Synthesis, characterization, and catalytic activity of a water soluble copper(II) and nickel(II) heterobimetallic complex [CuNi(μ-OH)(μ-OH2)(μ-OAc)(bpy)2](ClO4)2 in aqueous medium in the absence of a base and co-catalyst

A copper(II)–nickel(II)-based catalyst system has been synthesized and characterized by elemental analysis, molar conductance, mass spectra, magnetic moment, EPR, UV-Vis, IR spectroscopy, and cyclic voltammetry. The structure of the complex was established by X-ray crystallography. The complex is an efficient catalyst, which oxidizes primary and secondary alcohols to the corresponding aldehydes and ketones at 70 °C employing 15% H2O2 as the oxidant in the absence of a base and co-catalyst.

Synthesis and electrochemical properties of a water soluble nickel(II) complex supported by N-phenylpyridin-2-ylmethanimine ligand

The N-phenylpyridin-2-ylmethanimine ligand, HL reacts with NiCl2·6H2O to afford a water soluble nickel(II) complex, [Ni(HL)2Cl2] 1. Electrochemical studies exhibit that this complex acts as an electrocatalyst for water reduction to hydrogen from a neutral water (pH 7.0) with a TOF of 970.45mol of hydrogen per mole of catalyst per hour at an OP of 837.6mV. This can be attributed to the ligand HL, that coordinates through four nitrogen atoms to the nickel center and can stabilize low oxidation state of nickel well.

Preparation of nanosized nickel powder by direct-current electrolysis combined with high-voltage spark discharge

The possibility of obtaining nanosized nickel powder by simultaneous dc electrolysis and high-voltage spark discharge has been explored. The powder has been prepared from a nickel sulfate-containing electrolyte using soluble nickel anodes at a cathodic current density in the range of 11000–19000 A/m2, a voltage on the spark gap of 12–16 kV, and a pulse repetition frequency of 0.5 Hz. The effect of various factors on the synthesis of the powder has been studied and the optimum conditions for its preparation have been found using mathematical experiment design. The size distribution of particles has been determined with a particle size analyzer. The BET specific surface area of the powder has been measured to be 11.7 ± 2.1 m2/g.

Substitutional impact on biological activity of new water soluble Ni(II) complexes: Preparation, spectral characterization, X-ray crystallography, DNA/protein binding, antibacterial activity and in vitro cytotoxicity

A series of new water soluble nickel(II) complexes containing triphenylphosphine and 4-methoxysalicylaldehyde-4(N)-substituted thiosemicarbazones were synthesized and characterized. Crystallographic investigations confirmed the structure of the complexes (1–4) having the general structure [Ni(4-Msal-Rtsc)(PPh3)] (Where R=H (1); CH3 (2); C2H5 (3); C6H5 (4)) which showed that thiosemicarbazone ligands coordinated to nickel(II) ion as ONS tridentate bibasic donor. DNA/BSA protein binding ability of the ligands and their new complexes were studied by taking calf-thymus DNA (CT-DNA) and Bovine serum albumin (BSA) through absorption and emission titrations. Ethidium bromide (EB) displacement study showed the intercalative binding trend of the complexes to DNA. From the albumin binding studies, the mechanism of quenching was found as static and the alterations in the secondary structure of BSA by the compounds were confirmed with synchronous spectral studies. The binding affinity of the complexes to CT-DNA and BSA has the order of [Ni(4-Msal-etsc)(PPh3)] (3) >[Ni(4-Msal-mtsc)(PPh3)] (2) >[Ni(4-Msal-tsc)(PPh3)] (1) >[Ni(4-Msal-ptsc)(PPh3)] (4). In vitro cytotoxicity of the complexes was tested on human lung cancer cells (A549), human cervical cancer cells (HeLa), human liver carcinoma cells (Hep G2). All the complexes exhibited significant activity against three cancer cells. Among them, complex 4 exhibited almost 2.5 fold activity than cisplatin in A549 and HepG2 cell lines. In HeLa cell line, the complexes exhibited significant activity which is less than cisplatin. While comparing the activity of the complexes in A549 and HepG2 cell lines it falls in the order 4>1>2>3>cisplatin. The results obtained from DNA, protein binding and cytotoxicity studies, it is concluded that the cytotoxicity of the complexes as determined by MTT assay were not unduly influenced by the complexes having different binding efficiency with DNA and protein. The complexes exhibited good spectrum of antibacterial activity against four pathogenic bacteria such as E. faecalis (gram +ve), S. aureus (gram +ve), E. coli (gram −ve) and P. aeruginosa (gram −ve).

Hormonal Perturbations in Occupationally Exposed Nickel Workers.

BACKGROUND:Nickel exposure is recognized as an endocrine disruptor because of its adverse effects on reproduction.AIM:This study was designed to investigate the possible testiculo-hormonal perturbations on workers occupationally exposed to nickel and to assess its effects on human male sexual function.METHODS:Cross-sectional comparative study, comprising 105 electroplating male non-smoker, non-alcoholic workers exposed to soluble nickel and 60 controls was done. Serum luteinizing hormone, follicle stimulating hormone, testosterone levels and urinary nickel concentrations were determined for the studied groups.RESULTS:Serum luteinizing hormone, follicle stimulating hormone, urinary nickel and the simultaneous incidence of more than one sexual disorder were significantly higher in the exposed workers compared to controls. The occurrence of various types of sexual disorders (decreased libido, impotence and premature ejaculation) in the exposed workers was 9.5, 5.1 and 4.4 folds respectively than the controls.CONCLUSIONS:Exposure to nickel produces possible testiculo-hormonal perturbations in those exposed workers.

Nickel in equine sports drug testing - pilot study results on urinary nickel concentrations.

The issue of illicit performance enhancement spans human and animal sport in presumably equal measure, with prohibited substances and methods of doping conveying both ways. Due to the proven capability of unbound ionic cobalt (Co(2) (+) ) to stimulate erythropoiesis in humans, both human and equine anti-doping regulations have listed cobalt as a banned substance, and in particular in horse drug testing, thresholds for cobalt concentrations applying to plasma and urine have been suggested or established. Recent reports about the finding of substantial amounts of undeclared nickel in arguably licit performance- and recovery-supporting products raised the question whether the ionic species of this transition metal (Ni(2) (+) ), which exhibits similar prolyl hydroxylase inhibiting properties to Co(2) (+) , has been considered as a substitute for cobalt in doping regimens. Therefore, a pilot study with 200 routine post-competition doping control horse urine samples collected from animals participating in equestrian, gallop, and trotting in Europe was conducted to provide a first dataset on equine urinary Ni(2) (+) concentrations. All specimens were analyzed by conventional inductively coupled plasma mass spectrometry (ICP-MS) to yield quantitative data for soluble nickel. Concentrations ranging from below the assay's limit of quantification (LOQ, 0.5 ng/mL) up to 33.4 ng/mL with a mean value (± standard deviation) of 6.1 (±5.1) ng/mL were determined for the total nickel content. In horses, nickel is considered a micronutrient and feed supplements containing nickel are available; hence, follow-up studies are deemed warranted to consolidate potential future threshold levels concerning urine and blood nickel concentrations in horses using larger sets of samples for both matrices and to provide in-depth insights by conducting elimination studies with soluble Ni(2) (+) -salt species. Copyright © 2016 John Wiley & Sons, Ltd.

Nickel in a serpentine-enriched Fluvisol: Redox affected dynamics and binding forms

We determined redox-induced (im)mobilization of geogenic nickel (Ni) as well as binding forms of Ni in a Fluvisol at the River Velika Morava valley (Serbia), enriched with serpentine minerals. The selected site is representative for intensive agricultural land use in the area and susceptible to dynamic redox conditions due to periodical flooding. A seven-step sequential extraction, grain-size and light-liquid separation as well as mineralogical analyses were used, first, to assess binding forms of Ni and second, to determine relationships between grain-size fractions, abundance of heavy density minerals, and Ni concentration in the bulk soil. The sequential extraction revealed that the majority of Ni was in the residual fraction, followed by organic matter and Fe oxides. Fine grain-size fraction (<63μm) was the major location of accumulation of Ni in the soil. Minerals which are characteristic for serpentine soils such as serpentine, spinels, hematite, and magnetite were found in silt and in the heavy density fraction (>2.9gml−1) of the medium and fine sand. However, the light minerals quartz, chlorite, micas, and secondary clay minerals dominate the soil mineral composition. Thus, total Ni concentration in the soil is derived from the content of Ni-bearing minerals and diluted by the minerals which are low in Ni.We simulated flooding using an automated biogeochemical microcosm system and determined the release dynamics of Ni at controlled redox potentials (EH) in soil slurries. Pre-defined redox-windows were systematically created in steps of approximately 100mV from reducing to oxidizing conditions while EH and pH were continuously monitored. In parallel, the release dynamics of soluble nickel (Ni), iron (Fe), magnesium (Mg), manganese (Mn), dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and sulfate (SO42−) were measured at each EH-window. Our results highlighted that geogenic Ni can be mobilized to a considerable amount during low EH, while elevating EH from reducing to oxidizing conditions generated an immobilization Ni. We suggested that mobilization of Ni has been primarily affected by formation of Ni–DOC complexes at low EH, whereas Ni seems to be immobilized as a result of formation of Fe/Mn (hydro)oxides and the linked co-precipitation of Ni during oxidation. Factor analysis (FA) as multivariate statistical method explained 85.08% of the variance (67.89% and 17.19% component Nos. 1 and 2, respectively). The FA reveals that soluble Ni, Fe, DOC, Mn, and Mg were clustered in one group which indicate that the combined effect of DOC together with the chemistry of Fe, Mn, and Mg might be linked to the redox-induced release dynamics of Ni. The practical perspective of the study was to draw attention to dynamics of soluble Ni in fluctuating conditions for a better ecological risk assessment of floodplain sites under agricultural use. Nevertheless, similar studies should be conducted with further serpentine soils from various sites world-wide to verify the detected dynamics and processes.

Predicting Soluble Nickel in Soils Using Soil Properties and Total Nickel.

Soil soluble nickel (Ni) concentration is very important for determining soil Ni toxicity. In the present study, the relationships between soil properties, total and soluble Ni concentrations in soils were developed in a wide range of soils with different properties and climate characteristics. The multiple regressions showed that soil pH and total soil Ni concentrations were the most significant parameters in predicting soluble Ni concentrations with the adjusted determination coefficients (Radj 2) values of 0.75 and 0.68 for soils spiked with soluble Ni salt and the spiked soils leached with artificial rainwater to mimic field conditions, respectively. However, when the soils were divided into three categories (pH < 7, 7–8 and > 8), they obtained better predictions with Radj 2 values of 0.78–0.90 and 0.79–0.94 for leached and unleached soils, respectively. Meanwhile, the other soil properties, such as amorphous Fe and Al oxides and clay, were also found to be important for determining soluble Ni concentrations, indicating that they were also presented as active adsorbent surfaces. Additionally, the whole soil speciation including bulk soil properties and total soils Ni concentrations were analyzed by mechanistic speciation models WHAM VI and Visual MINTEQ3.0. It was found that WHAM VI provided the best predictions for the soils with pH < 7, was relatively reasonable for pH 7 to 8, and gave an overestimation for pH > 8. The Visual MINTEQ3.0 could provide better estimation for pH < 8 and meanwhile quite reasonable results for pH > 8. These results indicated the possibility and applicability of these models to predict soil soluble Ni concentration by soil properties.

Antimicrobial Air Filters Using Natural Euscaphis japonica Nanoparticles.

Controlling bioaerosols has become more important with increasing participation in indoor activities. Treatments using natural-product nanomaterials are a promising technique because of their relatively low toxicity compared to inorganic nanomaterials such as silver nanoparticles or carbon nanotubes. In this study, antimicrobial filters were fabricated from natural Euscaphis japonica nanoparticles, which were produced by nebulizing E. japonica extract. The coated filters were assessed in terms of pressure drop, antimicrobial activity, filtration efficiency, major chemical components, and cytotoxicity. Pressure drop and antimicrobial activity increased as a function of nanoparticle deposition time (590, 855, and 1150 µg/cm2filter at 3-, 6-, and 9-min depositions, respectively). In filter tests, the antimicrobial efficacy was greater against Staphylococcus epidermidis than Micrococcus luteus; ~61, ~73, and ~82% of M. luteus cells were inactivated on filters that had been coated for 3, 6, and 9 min, respectively, while the corresponding values were ~78, ~88, and ~94% with S. epidermidis. Although statistically significant differences in filtration performance were not observed between samples as a function of deposition time, the average filtration efficacy was slightly higher for S. epidermidis aerosols (~97%) than for M. luteus aerosols (~95%). High-performance liquid chromatography (HPLC) and electrospray ionization-tandem mass spectrometry (ESI/MS) analyses confirmed that the major chemical compounds in the E. japonica extract were 1(ß)-O-galloyl pedunculagin, quercetin-3-O-glucuronide, and kaempferol-3-O-glucoside. In vitro cytotoxicity and disk diffusion tests showed that E. japonica nanoparticles were less toxic and exhibited stronger antimicrobial activity toward some bacterial strains than a reference soluble nickel compound, which is classified as a human carcinogen. This study provides valuable information for the development of a bioaerosol control system that is environmental friendly and suitable for use in indoor environments.

Thiolate-protected Ni39 and Ni41 nanoclusters: synthesis, self-assembly and magnetic properties.

Thiolate-protected soluble nickel clusters, Ni(39)(SC(2)H(4)Ph)24 and Ni(41)(SC(2)H(4)Ph)25, were synthesized via a wet chemical method. The cluster formulae were identified by MALDI-TOF. Possible structures of the clusters were discussed. These clusters exhibit ferromagnetism with hysteresis loops in the 1.8-300 K range. By solvent evaporation, the clusters can self-assemble into simple cubic structured crystals with a width in the range of 1-10 μm and length up to 300 μm. These properties shed light on their application potentials in nanomagnetics working at room temperature.

Evaluation the Influence of Soil Solution Chemistry on Soluble Nickel Toxicity to Bok Choy

Nickel (Ni) is an essential element for plants but it is toxic at large concentrations. In the present study, bioassays of bok choy were taken in 17 Chinese soils with different properties and climate characteristics to evaluate the toxicity of soil soluble nickel (Ni) toxicity in soil pore water to bok choy. The tested soils were spiked with 8 levels of soluble Ni chloride with or without leaching treatments. The effective soluble Ni concentrations that caused 10% root growth inhibition (EC10) and 50% inhibition (EC50) varied widely from 0.05 to 2.1 mg/L and from 0.13 to 7.6 mg/L in 17 unleached soils, represented 41.8 to 58.5 folds differences, and from 0.08 to 2.2 mg/L and from 0.47 to 4.5 mg/L in leached soils, represented 27 to 9.6 folds differences. It indicated that the soil soluble properties greatly influenced Ni toxicity to bok choy. However, soluble Ni toxicity thresholds were not significantly decreased in 15 soils. Regression models between soil solution properties and phytotoxicity threshold values were developed. The model showed that soil solution Mg2+K+ and electrical conductivity (EC) were the important factors affecting Ni toxicity on bok choy, and meanwhile they were positively related to the toxicity thresholds. These quantitative relationships could be used for the risk assessment of Ni in terrestrial environment in China.

Role of Hypoxia-Inducible Factor 1, α Subunit and cAMP-Response Element Binding Protein 1 in Synergistic Release of Interleukin 8 by Prostaglandin E2 and Nickel in Lung Fibroblasts

Numerous epidemiological studies have linked exposure to particulate matter (PM) air pollution with acute respiratory infection and chronic respiratory and cardiovascular diseases. We have previously shown that soluble nickel (Ni), a common component of PM, alters the release of CXC chemokines from cultured human lung fibroblasts (HLF) in response to microbial stimuli via a pathway dependent on disrupted prostaglandin (PG)E2 signaling. The current study sought to identify the molecular events underlying Ni-induced alterations in PGE2 signaling and its effects on IL-8 production. PGE2 synergistically enhances Ni-induced IL-8 release from HLF in a concentration-dependent manner. The effects of PGE2 were mimicked by butaprost and PGE1-alcohol and inhibited with antagonists AH6809 and L-161,982, indicating PGE2 signals via PGE2 receptors 2 and 4. PGE2 and forskolin stimulated cAMP, but it was only in the presence of Ni-induced hypoxia-inducible factor 1, α subunit (HIF1A) that these agents stimulated IL-8 release. The Ni-induced HIF1A DNA binding was enhanced by PGE2 and mediated, in part, by activation of p38 MAPK. Negation of cAMP-response element binding protein 1 or HIF1A using short interfering RNA blocked the synergistic interactions between Ni and PGE2. The results of the current study provide novel information on the ability of atmospheric hypoxia-mimetic metals to disrupt the release of immune-modulating chemokines by HLF in response to PGE2. Moreover, in the presence of HIF1A, cAMP-mediated signaling pathways may be altered to exacerbate inflammatory-like processes in lung tissue, imparting a susceptibility of PM-exposed populations to adverse respiratory health effects.

Disturbance of aerobic metabolism accompanies neurobehavioral changes induced by nickel in mice

The oral ingestion of soluble nickel compounds leads to neurological symptoms in humans. Deficiencies in aerobic metabolism induced by neurotoxic stimulus can cause an energy crisis in the brain that results in a variety of neurotoxic effects. In the present study, we focused on the aerobic metabolic states to investigate whether disturbance of aerobic metabolism was involved in nickel-induced neurological effects in mice. Mice were orally administered nickel chloride, and neurobehavioral performance was evaluated using the Morris water maze and open field tests at different time points. Aerobic metabolic states in the cerebral cortex were analyzed at the same time points at which neurobehavioral changes were evident. We found that nickel exposure caused deficits in both spatial memory and exploring activity in mice and that nickel was deposited in their cerebral cortex. Deficient aerobic metabolism manifested as decreased O2 consumption and ATP concentrations, lactate and NADH accumulation, and oxidative stress. Meanwhile, the activity of prototypical iron–sulfur clusters (ISCs) containing enzymes that are known to control aerobic metabolism, including complex I and aconitase, and the expression of ISC assembly scaffold protein (ISCU) were inhibited following nickel deposition. Overall, these data suggest that aerobic metabolic disturbances, which accompanied the neurobehavioral changes, may participate in nickel-induced neurologic effects. The inactivation of ISC containing metabolic enzymes may result in the disturbance of aerobic metabolism. A better understanding of how nickel impacts the energy metabolic processes may provide insight into the prevention of nickel neurotoxicity.

Soluble Nickel Nanoparticles for Catalytic Hydrogenation

With the rapid development of materials science, the noble metal nanoparticles (NPs) with tunable size and shape have attracted much attention because the tailored nanoparticles affected the catalytic performance tremendously. Besides the noble metal nanoparticles, the easily available transition metal nanoparticles such as Ni-NPs have also been utilized as catalysts recently for various kinds of reactions. In this review, we presented primarily work towards the preparation approach for Ni nanoparticles with predictable and controllable size, shape, composition, and morphology. Especially, the synthetic routes to the controllable Ni nanoparticles through chemical reduction, thermal decomposition, ultrasonic and microwave irradiation, coupling with using reasonably environment-friendly, low cost alternative solvent systems like ionic liquid or w/o microemulsion were illustrated. The particular attention has been given to the recent research progress in employing Ni nanoparticles as catalysts in catalytic hydrogenation of olefins, α, β-unsaturated aldehydes and derivatives of nitrobenzene, and decisive factors influencing the catalytic activity of Ni nanoparticles were then summarized. Keywords: Nickel nanoparticles, Stabilization, Hydrogenation, Catalysis, Immobilization

A Heterogeneous Nickel Catalyst for the Hydrogenolysis of Aryl Ethers without Arene Hydrogenation

A heterogeneous nickel catalyst for the selective hydrogenolysis of aryl ethers to arenes and alcohols generated without an added dative ligand is described. The catalyst is formed in situ from the well-defined soluble nickel precursor Ni(COD)(2) or Ni(CH(2)TMS)(2)(TMEDA) in the presence of a base additive, such as (t)BuONa. The catalyst selectively cleaves C(Ar)-O bonds in aryl ether models of lignin without hydrogenation of aromatic rings, and it operates at loadings down to 0.25 mol % at 1 bar of H(2) pressure. The selectivity of this catalyst for electronically varied aryl ethers differs from that of the homogeneous catalyst reported previously, implying that the two catalysts are distinct from each other.

Robust Photogeneration of H 2 in Water Using Semiconductor Nanocrystals and a Nickel Catalyst

Homogeneous systems for light-driven reduction of protons to H(2) typically suffer from short lifetimes because of decomposition of the light-absorbing molecule. We report a robust and highly active system for solar hydrogen generation in water that uses CdSe nanocrystals capped with dihydrolipoic acid (DHLA) as the light absorber and a soluble Ni(2+)-DHLA catalyst for proton reduction with ascorbic acid as an electron donor at pH = 4.5, which gives >600,000 turnovers. Under appropriate conditions, the precious-metal-free system has undiminished activity for at least 360 hours under illumination at 520 nanometers and achieves quantum yields in water of over 36%.

Effect of sulfur forms on concentrations of cadmium and nickel soluble in 1 mol HCl dm-3 in arable soils

Heavy metal contamination of arable soils remains one of the world’s most serious environmental problems. The mobility of heavy metals in soil is determined by soil conditions, environmental factors and human activity. The immediate and residual effects of sulfur fertilization on the concentrations of heavy metals in soil are an important consideration when monitoring changes in environmental conditions in agricultural areas. The objective of this study was to determine the effect of increasing doses of sulfate and elemental sulfur on changes in the concentrations of cadmium and nickel soluble in 1 mol HCl dm –3 in soil samples collected at a depth of 0-40 and 40-80 cm. A three-year field experiment was conducted on Dystric Cambisols (FAO) of the texture of heavy loamy sand. Soil samples were collected from each plot, prior to the establishment of the trials, after each harvest and before sowing the consecutive crop. The soil samples were used to determine the concentrations of Cd and Ni in soil (extractions with 1 mol HCl dm –3 , the ratio between soil and extraction - 1:10) by the AAS method using a Schimadzu AA apparatus. Irregular changes in soluble cadmium concentrations were observed in soil fertilized with sulfate and elemental sulfur. No distinct trends were noticed in response to sulfate and elemental sulfur fertilization. The effect of sulfur was noticeable only in the third year of the experiment. Sulfur application contributed to a decrease in the soluble nickel content of soil. Sulfate and elemental sulfur fertilization did not increase the levels of cadmium and nickel soluble in 1 mol HCl dm –3 . The soil can be used for growing high-quality

Short term effects of vanadium and nickel intoxication on rats liver antioxidant defence system

Hoda E. A. Farid, Medhat M. Abozid*, Kamal E. Mahmoud Department of Biochemistry, Faculty of Agricultural, Minufiya University (EGYPT) *Corresponding author: medh_latef@yahoo.com DOI: 10.7813/2075-4124.2012/4-5/A.2 ABSTRACT The present study was performed to investigate short term effects of vanadium and nickel intoxication on rats liver antioxidant defence system. After 4 weeks of oral treatment of 150 mg vanadium (V) /L or 180 mg nickel (Ni) /L and their combination. At the end of treatment, malondialehyde (MDA) level in liver tissues and serum alanine-(ALT) and aspartate-(AST) aminotransferase activities were increased but the antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT) activities were decreased significantly. Significant decrease was observed in the glutathione (GSH) content in all groups compared with control. Glutathione-S-transferase (GST) activity was showed the same behavior. Joint action analysis of vanadium, nickel and their mixture, depending upon biochemical data measurements showed antagonistic (An) effects in ALT, AST, GST, GSH, SOD and MDA while, additive effect (Ad) was found in CAT. In conclusion, vanadium and nickel treatments caused profound cell damage as indicated by increased MDA in liver and leakage of intracellular enzymes, ALT and AST to the blood, as well as decrease in antioxidant biomarkers. Key words: vanadium, nickel, antioxidant enzymes, malondialdehyde, rat. 1. INTRODUCTION There has been a growing interest for heavy metals, in recent years, studies on impact of trace heavy metals have continued to assume increasing relevance especially in the areas of petroleum chemistry and toxicology [1]. Metals play important roles in a wide variety of biological processes of living systems. Homeostasis of metal ions, maintained through tightly regulated mechanisms of uptake, storage and secretion is therefore critical for life and is maintained within strict limits [2]. Despite the fact that some studies showed its beneficial pharmaceutical effects, vanadium therapeutically exposure and the exposure associated with taking vanadium supplements, especially those which can provide more than 10 mg V/day [3], should be taken into consideration. Long-term intake of even small doses of vanadium could be toxic; no recommended dietary allowance has been clearly established [4]. The main target organ for nickel induced toxicity in animals is the respiratory tract [5]. The toxicity of nickel compounds appears to be related to the solubility of the compound. Several acute animal studies have reported soluble nickel sulfate as being the most toxic and insoluble nickel oxide the least toxic [6]. Vanadium and nickel metals not only are present in residual waters from the oil industry but also can be present as particulate matter in inhaled air [7] and as environmental heavy metals emitted from automotive materials [8]. Both metals are also present as aerosols or in the ashes of thermal power stations operating on oil fuel [9]. The recovery of heavy metals from industrial residues is an important task for environmental and economic reasons [10]. Although toxicity of individual heavy metals has been studied extensively, [11] the toxicological impact of a mixture is relatively less understood. Therefore, studies on mixture of heavy metals are necessary in order to understand their interactions on the living system and to evaluate their risk assessment [12]. Considering the above- stated, the toxic effect of vanadium and nickel in liver of rats after separate and combined exposures was planned to be carried in the present research by using antioxidant indices and marker enzymes of tissue damage (aminotransferases) as biochemical indicators. 2. MATERIALS AND METHODS 2.1. Chemicals Kits for glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were obtained from gamma trade company, Egypt. Ammonium metavanadate (NH

Reproductive toxicology of nickel – Review

The goal of this minireview is to summarize our current knowledge on the reproductive toxicity of soluble nickel salts. We made an attempt to present the most relevant data obtained from in vivo and in vitro experiments performed on mammals, mammalian primary cell cultures and cell lines. Nickel has been demonstrated to disturb the mammalian reproductive functions at several levels of regulation. The results of previous investigations indicate that the hormonal effects may play an important role in the reproductive toxicology of nickel both at the neuroendocrine and gonadal levels in the hypothalamic-pituitary-gonadal (HPG) axis. At the molecular level, it may be important that nickel may substitute certain other metals in metal dependent enzymes, leading to an altered protein function. It readily crosses the cell membrane via calcium channels and competes with calcium for specific receptors. Nickel can cross-link aminoacids to DNA, lead to formation of reactive oxygen species (ROS), moreover mimic hypoxia. These changes may lead to the activation of some signaling pathways, subsequent transcription factors and eventually to alterations in gene expression and cellular metabolism. These events are likely to be involved in the reproductive toxicity of nickel.