Metal ions affect neuronal membrane fluidity of rat cerebral cortex

The effect of various metal ions on neuronal membrane fluidity was examined using 2-(14-carboxypropyl)-2-ethyl-4,4-dimethyl-3-oxazolidinyloxy, which has been used for the examination of membrane fluidity in hydrophobic areas by electron spin resonance spectrometry. Potassium, cobalt, calcium, magnesium, nickel, copper, ferric, and aluminium ions decreased the membrane fluidity while ferrous ions increased it at each high concentration. Sodium and zinc ions had no effect. Ethylenediaminetetraacetic acid decreased membrane fluidity at high concentrations. Nicardipine lowered membrane fluidity and flunarizine elevated it at each high concentration. There was no change in membrane fluidity by other calcium antagonists, nimodipine and nifedipine.     

Effects of cobalt, magnesium, and cadmium on contraction of rat soleus muscle.

The effects on isometric tension of three divalent ions that block calcium channels, magnesium, cobalt, and cadmium, were tested in small bundles of rat soleus fibers. Cobalt, at a concentration of 2 or 6 mM, reversibly depressed twitch and tetanic tension and the depression was much greater in solutions containing no added calcium ions. Magnesium caused much less depression of tension than cobalt. The depression of tension was not accompanied by membrane depolarization or a reduction in the amplitude of action potentials. A reduction caused by 6 mM cobalt in the amplitude of 40 or 80 mM potassium contractures was not accompanied by a comparable reduction in tension during 200 mM potassium contractures, and could be explained by a shift in the potassium contracture tension-voltage curve to more positive potentials (by +7 mV on average). Similar effects were not seen with 2 or 6 mM magnesium. At a concentration of 20 mM, both cobalt and magnesium depressed twitch and tetanic tension, cobalt having greater effect than magnesium. Both ions shifted the potassium contracture tension-voltage curve to the right by +5 to +10 mV, caused a small depression of maximum tension, and slowed the time course of potassium contractures. Cadmium (3 mM) depressed twitch, tetanic, and potassium contracture tension by more than 6 mM cobalt, but experiments were complicated by the gradual appearance of large contractures that became even larger, and sometimes oscillatory, when the solution containing cadmium was washed out. It was concluded that divalent cations affect both activation and inactivation of tension in a manner that cannot be completely explained by a change in surface charge.     

EDTA chelation effects on urinary losses of cadmium, calcium, chromium, cobalt, copper, lead, magnesium, and zinc

The efficacy of a chelating agent in binding a given metal in a biological system depends on the binding constants of the chelator for the particular metals in the system, the concentration of the metals, and the presence and concentrations of other ligands competing for the metals in question. In this study, we make a comparison of the in vitro binding constants for the chelator, ethylenediaminetetraacetic acid, with the quantitative urinary excretion of the metals measured before and after EDTA infusion in 16 patients. There were significant increases in lead, zinc, cadmium, and calcium, and these increases roughly corresponded to the expected relative increases predicted by the EDTA-metal-binding constants as measured in vitro. There were no significant increases in urinary cobalt, chromium, or copper as a result of EDTA infusion. The actual increase in cobalt could be entirely attributed to the cobalt content of the cyanocobalamin that was added to the infusion. Although copper did increase in the post-EDTA specimens, the increase was not statistically significant. In the case of magnesium, there was a net retention of approximately 85% following chelation. These data demonstrate that EDTA chelation therapy results in significantly increased urinary losses of lead, zinc, cadmium, and calcium following EDTA chelation therapy. There were no significant changes in cobalt, chromium, or copper and a retention of magnesium. These effects are likely to have significant effects on nutrient concentrations and interactions and partially explain the clinical improvements seen in patients undergoing EDTA chelation therapy.     

Inhibition of 2'-5' oligoadenylate synthetase by divalent metal ions.

OAS1 is the small form and OAS2 is the medium form of the human interferon-induced 2'-5' oligoadenylate synthetases. The p42 isoform of OAS1 and the p69 isoform of OAS2 have been expressed in insect cells and purified to give pure, highly active 2'-5' oligoadenylate synthetase. The catalysis of 2'-5' oligoadenylate synthesis is strictly dependent on double-stranded RNA and magnesium ions. We have examined the effect of a series of divalent metal ions: copper, iron and zinc ions strongly inhibited the enzymatic activity, cobalt and nickel ions were partly inhibitory whereas calcium and manganese ions were without effect. However, manganese ions can replace magnesium ions as activator. The inhibitory effect of zinc ions was characterised in detail. The inhibitory constants of Zn(2+) were estimated to be 0.10 mM for OAS1p42 and to 0.02 mM for OAS2p69. Cross-linking experiments showed that zinc ions can control the oligomerisation by enhancing the formation of tetrameric forms of OAS1p42     

A Stopped-Flow Method for the Determination of Ascorbic Acid in Orange Juice Containing Triose Reductone

The adsorption of uranium by chitin phosphate and chitosan phosphate was investigated to obtain information on uranium recovery from aqueous systems, especially sea water and uranium mine waste water. The adsorption of uranium by chitin phosphate and chitosan phosphate was much greater than copper, cadmium, manganese, zinc, cobalt, nickel, magnesium and calcium. The adsorption of uranium was very rapid during the first 10 min and was affected by pH of the solution, temperature, granule radius and the co-existence of carbonate ion. The amounts of uranium adsorbed on the adsorbents increased linearly as the external uranium concentration increased. Uranium adsorbed on chitin phosphate easily desorbed with diluted sodium carbonate solution. On the other hand, uranyl and cobalt ions were separated from each other by using chitin phosphate.     

The effect of ions, ion channel blockers, and ionophores on uptake of vitellogenin into cockroach follicles

Since calcium plays an important role in vitellogenin binding and uptake in Nauphoeta cinerea and because calcium channels have been described in follicles of this species, we investigated the effect of various ions, ionophores, and ion channel blockers on vitellogenin uptake in vitro. Calcium significantly stimulated vitellogenin uptake; this effect could be substituted best by barium and less well by strontium and magnesium. The stimulatory effect of calcium, and to a certain extent also that of barium, was dependent on the vitellogenin concentration, whereas the effect of strontium and magnesium was not. In the presence of calcium, vitellogenin uptake was inhibited by barium, strontium, and magnesium as well as by the transition elements nickel, cobalt, and zinc, but not by manganese which had a stimulatory effect. Valinomycin, verapamil, tetraethylammonium, and atropine reduced vitellogenin uptake, while amiloride and ouabain were ineffective. Our results indicate that calcium inward (and possibly potassium outward) fluxes play an important role in vitellogenin uptake.     

Inorganic elements in the adults of Ascaridia galli (Schrank, 1788)

Inorganic analysis of Ascaridia galli has shown the levels of sodium, potassium, copper, magnesium, calcium, zinc, iron, nitrogen, phosphorus, sulphur, chlorine and cobalt (expressed as percentage of dry weight) to be higher in females than in males.     

Inactivation of tyrosine 3-monooxygenase by acetone precipitation and its restoration by incubation with a sulfhydryl agent and iron

The acetone precipitation of a partially purified tyrosine 3-monooxygenase (L-tyrosine, tetrahydropteridine: oxygen oxidoreductase (3-hydroxylating), EC 1.14.16.2) resulted in the complete loss of enzymatic activity. The enzymatic activity was restored by incubation with iron and dithiothreitol. The restoration of the activity was a pH-, temperature- and time-dependent reaction. Since cobalt, nickel, copper, zinc, manganese, cadmium, magnesium calcium and barium ions were all ineffective in restoring activity, iron ion appeared to be specifically required in the restoration of the enzyme activity. Dithiothreitol could be partially replaced in the restoration step by glutathione, 2-mercaptoethanol or cysteine.     

Modification of radiosensitivity of chlorpromazine with biological metal ions in Thiobacillus ferrooxidans

Effect of chlorpromazine with biological metal ions, viz. calcium, magnesium, zink and copper was studied on T. ferrooxidans cell system. Chlorpromazine, calcium and magnesium alone could produce radioprotection. Maximum radioprotection was exhibited by chlorpromazine at lower concentration while copper and zink offered radiosensitization. However, combination of chlorpromazine with all biological metal ions exhibited radiosensitization. Dose modifying factor by chlorpromazine at lower concentration (0.025 mM) was 0.754 while in combination with Ca2+, Mg2+, Cu2+ and Zn2+ was 1.08, 1.25, 1.37 and 1.389 respectively. The possible interaction between chlorpromazine and biological metal ions is discussed at cellular membrane level.     

Effect of calcium ion uptake on Candida albicans morphology

In liquid culture using a synthetic medium, added magnesium but not calcium was required for exponential growth of Candida albicans yeast cells. However, medium without added divalent cations supported 2-3 generations of yeast growth or germ tube induction. The addition of calcium ions (1.0 mM) at any stage during the induction of germ tube formation caused reversion to a yeast mode of growth, in contrast to the effect of zinc and cobalt ions which were toxic to all growth. Inhibition of germ tube formation by calcium was not observed in the presence of either magnesium (10 microM) or manganese (100 microM). The presence of either of these ions caused inhibition of 45Ca uptake in yeast cultures. We conclude that unrestricted calcium uptake resulted in the specific inhibition of C. albicans mycelial growth, indicating a critical role for calcium in the regulation of C. albicans morphogenesis.     

Cations in Hemolymph and Alimentary Tract Tissues of Healthy and Milky Diseased European Chafer (Amphimallon majalis) Larvae

A study was made of certain cations present in hemolymph and alimentary tract tissues of healthy and diseased European chafer larvae and the spores of Bacillus popilliae collected from diseased hemolymph. The major ions found in the hemolymph, in order of decreasing abundance, were potassium, magnesium, sodium, and calcium. Hemolymph of diseased larvae contained relatively higher concentrations of sodium, potassium, magnesium, iron, and zinc than hemolymph of healthy larvae. Concomitantly, the concentrations of ions were lower in the mid-gut and anterior intestinal tissues of diseased larvae. Only sodium decreased slightly in the diseased tissues of the rectum and rectal sac; other ions remained unchanged or increased. Little or no manganese or copper was detected in the hemolymph or tissues. The major cations of spores of B. popilliae were sodium, calcium, and magnesium. Small amounts of potassium, manganese, copper, iron, and zinc were detected in the spores. Based on calcium and dipicolinic acid determinations of the spores, sufficient calcium was found to allow for the formation of calcium dipicolinate in the expected concentrations.     

The influence of a specific microelemental environment in alginate gel beads on the course of propionic acid fermentation

In this work the exchange of calcium, cobalt, iron, magnesium, zinc and manganese ions between alginate gel beads and casein medium was investigated. The high release of calcium ions from alginate to the medium and the biosorption of some metal ions were observed. The pure alginate gel adsorbed all the metal ions examined, from a fermentative medium. Gel with immobilized cells of two strains of Propionibacterium freudenreichii subsp. shermanii showed an active ability to adsorb only cobalt, iron and zinc ions. In this way, a special microelemental environment was created in the alginate gel. This resulted in an increase of propionic acid production and a decrease of vitamin B₁₂ biosynthesis. Received: 30 April 1997 / Received revision: 2 July 1997 / Accepted: 4 July 1997     

Serum Levels of Zinc,Copper, Iron,Cobalt, Magnesium,and Selenium Elements in Children Diagnosed with <Emphasis Type="Italic">Giardia Intestinalis</Emphasis> and <Emphasis Type="Italic">Enterobiosis Vermicularis</Emphasis> in Hatay,Turkey

The intestinal parasites are noted to be an important health problem in Turkey as similarly reported in the globe. The aim of this study was to investigate the changes in total content of essential elements, namely, zinc, iron, copper, cobalt, magnesium, and selenium, in children infected with intestinal parasites aged between 6 and 12 years inhabiting in Hatay Province, Turkey. These essential elements were measured in the children/patient who was positive for intestinal parasites, Giardia intestinalis and Enterobius vermicularis. Scores were obtained from the positive study group (SG), and their age matched the healthy children control group (CG). Serological levels of zinc, iron, copper, cobalt, magnesium, and selenium were analyzed by Varian Liberty Series II inductively coupled plasma atomic emission spectrometer (ICP-AES). The mean magnesium concentrations were found to be statistically different at 95% confidence interval level between study groups. As a result of this study, selenium was found to be uncorrelated with all other elements examined; whereas, copper was observed to have statistically significant correlations with cobalt, magnesium, and zinc. In addition, cobalt-magnesium, cobalt-zinc, and magnesium-zinc metal pairs were found to have statistically significant correlations based on study findings.     

Characterization of a cobalt-resistant mutant of Neurospora crassa with transport block

A cobalt-resistant strain of Neurospora crassa (cor) was obtained by repeated subculturing of the wild type on cobalt-containing agar medium. N. crassa cor is twentyfold more resistant to cobalt ions compared with the wild type. Resistance was stable on repeated subculturing of cor on cobalt-free media. N. crassa cor is also cross-resistant to nickel (fourfold), but not to zinc or copper. Higher concentrations of iron and magnesium ions are required to reverse growth inhibition due to cobalt toxicity in N. crassa cor, compared with the wild type. Germinating conidia and mycelia of the cor strain accumulated lower levels of cobalt ions compared with the parent N. crassa. The partial transport block for cobalt uptake is shown to be primarily due to decreased surface binding of cobalt to mycelia and cell walls. Efflux of mycelial cobalt was also observed in wild type and cobalt-resistant N. crassa. The characteristics of cor in comparison with wild type N. crassa are discussed in relation to the mechanisms of cobalt resistance.     

The Distribution of some Inorganic Elements in Plant Tissue 2

Tomato plants were fed with calcium 45, cobalt 60, copper 64,iron 59, magnesium 28, manganese 54, molybdenum 99, potassium42, sodium 24, tungsten 187, and zinc 65 in sand or water culture.Fresh tissues were then extracted with a series of reagents,and the percentage radioactivity determined in each fraction.Apart from calcium and iron, a measurable proportion of theassimilated activities were found in a form soluble in ethanol:the nature of the soluble cobalt and zinc complexes was investigated.Almost all the elements were removed by treatment with dilutehydrochloric and perchloric acids, but significant amounts ofiron and cobalt were left in the residue.     

Effect of aldosterone on the serum zinc, copper, and magnesium concentrations in the rat

Possible regulation of trace metal metabolism by various steroid hormones has been reported by a number of investigators. The purpose of the present study was to determine the effect of aldosterone on the serum copper, zinc, and magnesium concentrations in the rat. Male and female rats were infused with aldosterone for up to 72 h and the serum copper, zinc, and magnesium concentrations were determined. The serum zinc concentration exhibited a transient decrease with a nadir at 24 h. No significant change was observed in serum magnesium or copper that was directly attributable to aldosterone. The mechanism by which aldosterone affects the transient serum zinc decrease was not demonstrated, but several possibilities were discussed.     

Tracing the toxic ions of an endodontic tricalcium silicate-based sealer in local tissues and body organs

BackgroundThis study aimed to track the toxic ions released by MTA Fillapex, BioRoot RCS, and an experimental tricalcium silicate-based sealer (CEO) into local and distant tissues as well as to investigate their potential adverse effects. In addition, the chemical constituents of the sealers were also evaluated. The main components of the dry powders, pastes, and mixed sealers were characterized.Material and methodsDry powder and sealer discs were each set for 72 h and their main components were characterized by energy dispersive X-ray spectroscopy. Polyethylene tubes filled with sealers were used to measure silicon and calcium ions. Polyethylene tubes filled with sealers or empty tubes were implanted into the dorsal connective tissue of Wistar rats. On days 7, 15, 30, and 45, the animals were euthanized and their brains, livers, kidneys, and subcutaneous tissues were removed and processed to determine the concentrations of chromium, cobalt, copper, lead, iron, magnesium and nickel using an inductively coupled plasma optical emission spectrometer.ResultsThe main compounds in all sealers were carbon, oxygen, silicon, and calcium. MTA Fillapex release more Si while highest levels of Si were found in presence of BioRoot. The release of Si and Ca ions promoted by MTA Fillapex raise by time. No traces of cobalt, chromium, or magnesium were detected in any tissue. Irrespective of the sealer, no traces of copper and lead were found in the subcutaneous tissue; however, they were observed in the organs. The highest concentration of iron was identified in the liver. All sealers exhibited similar nickel traces in the brain, kidney, and liver except for MTA Fillapex, which demonstrated levels higher than CEO in the subcutaneous tissue on day 7. Tracing nickel ions over time revealed that lowest concentrations were found in subcutaneous tissue.ConclusionTaken together, our data demonstrate that CEOs have chemical compositions similar to those of other commercial sealers. Furthermore, none of them exhibited a threat to systemic health. Moreover, the minimal amounts of iron and nickel detected were not related to the sealers.     

Metals affect the structure and activity of human plasminogen activator inhibitor-1. II. Binding affinity and conformational changes

Human plasminogen activator inhibitor type 1 (PAI-1) is a serine protease inhibitor with a metastable active conformation. The lifespan of the active form of PAI-1 is modulated via interaction with the plasma protein, vitronectin, and various metal ions. These metal ions fall into two categories: Type I metals, including calcium, magnesium, and manganese, stabilize PAI-1 in the absence of vitronectin, whereas Type II metals, including cobalt, copper, and nickel, destabilize PAI-1 in the absence of vitronectin, but stabilize PAI-1 in its presence. To provide a mechanistic basis for understanding the unusual modulation of PAI-1 structure and activity, the binding characteristics and conformational effects of these two types of metals were further evaluated. Steady-state binding measurements using surface plasmon resonance indicated that both active and latent PAI-1 exhibit a dissociation constant in the low micromolar range for binding to immobilized nickel. Stopped-flow measurements of approach-to-equilibrium changes in intrinsic protein fluorescence indicated that the Type I and Type II metals bind in different modes that induce distinct conformational effects on PAI-1. Changes in the observed rate constants with varying concentrations of metal allowed accurate determination of binding affinities for cobalt, nickel, and copper, yielding dissociation constants of ～40, 30, and 0.09 μM, respectively. Competition experiments that tested effects on PAI-1 stability were consistent with these measurements of affinity and indicate that copper binds tightly to PAI-1.     

TOXIC EFFECTS OF HEAVY METALS ON CROP PLANTS GROWN IN SOIL CULTURE

A number of pot experiments were made on various crops, to study the effects on the chemical composition of the plants of treating the soil with cobalt, copper or nickel sulphates, or with the cupric or ferric salts of ethylenediamine-tetraacetic acid (EDTA).
The tops of copper sulphate-treated plants usually contained higher concentrations of copper, manganese, calcium and magnesium and lower concentrations of potassium and phosphorus, than those of control plants.
The most marked effect of cobalt on oat was to increase the concentration of Ca+Mg in the tops; nickel had a profound effect on the composition of barley tops.
Total iron concentration was reduced in oat by cobalt and copper, and in barley by copper and nickel application. Symptoms of iron deficiency appeared only in the oat plants, their incidence being correlated with the reduction in iron concentration in the tops.
The ferric salt of EDTA tended to reduce the incidence of iron deficiency symptoms produced in oat by copper sulphate, but also gave rise to distinct toxic effects. Plants given the cupric salt of EDTA contained unusually large amounts of iron.     

Acid and alkaline phosphatase activity in Trypanosoma cruzi epimastigotes

Phosphatase activity in intact Trypanosoma cruzi epimastigotes has been demonstrated. After subcellular fractionation three activities were characterized: (a) a membrane-bound microsomal acid activity with an optimum pH of 4.0 and a Km of 1.2 mM, strongly inhibited by tartrate and fluoride; (b) a soluble cytosolic acid activity with an optimum pH of 5.5 and a Km of 0.95 mM, strongly inhibited by p-hydroxymercuribenzoate, EDTA and copper ions and activated by cyanide, manganese and magnesium ions; and (c) a soluble cytosolic alkaline activity with an optimum pH of 8.0 and a Km of 3.8 mM, inhibited by p-hydroxymercuribenzoate, fluoride, EDTA, and copper, calcium and zinc ions. This activity was increased by magnesium and manganese ions.