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PubMed2005

Surfactant charge effects on the location, vibrational spectra, and relaxation dynamics of cyanoferrates in reverse micelles.

Ultrafast infrared spectroscopy has been used to measure vibrational energy relaxation (VER) and reorientation (Tr) times for the high frequency CN stretches of potassium ferrocyanide and ferricyanide and the NO stretch of sodium nitroprusside (SNP) in several reverse micelle (RM) systems using cationic, anionic, and nonionic surfactants. The confinement effects on anion vibrational spectra and dynamics in aqueous RMs depend on the charge of the surfactant that is used to form the RMs. Spectra and VER dynamics of ferrocyanide are not significantly altered in the limited number of RMs in which it could be solubilized. The static spectra of ferricyanide suggest an environment that is most bulklike in anionic RMs and least bulklike in cationic RMs. The dynamics of ferricyanide are slower in cationic RMs and indistinguishable from the bulk in nonionic RMs. The VER dynamics and static spectra of SNP are indistinguishable from the bulk in anionic RMs, but much slower in cationic RMs. This suggests a strong surfactant-solute repulsion in the former and an attraction in the latter. Broad static spectra and probe frequency dependent dynamics are seen for SNP in nonionic RMs, indicating an inhomogeneous distribution of environments. Similar measurements were carried out for SNP in mixtures of water and a model compound containing only the hydrophilic portion of the nonionic surfactants in which RMs are not formed. The results closely resemble those observed for SNP in nonionic RMs and provide evidence that in the latter water penetrates the interface and hydrates the ethylene oxide groups before forming a water pool. The results are consistent with the explanation that Coulombic forces determine the anion location. The anions are repelled to the interior of the water pool, which has a bulklike environment in anionic RMs, and are attracted to the interface in cationic RMs, resulting in a strong interaction with the surfactant. The solute location in the nonionic RMs depends on the hydrophilic nature of the probe, with ferrocyanide and ferricyanide being more hydrophilic than SNP. These results and the dependence on surfactant charge are similar to those reported for azide.

Cyanides↗
PubMed1979

Fe(III)-EDTA complex as iron fortification. Further studies.

The data presented confirm the advantages of Fe(III)-EDTA as a salt for iron fortification. This iron compound exchanges completely with intrinsic wheat iron in the lumen of the gut. The iron absorption data from this salt tested with six different food vehicles compared with the absorption of ferrous sulfate administered with the same vehicles indicate that while the mean absorption from ferrous sulfate varies from 2 to 30% according to the food vehicle mixed with the salt, the absorption from Fe(III)-EDTA remains practically the same. Apparently, the iron absorption from Fe(III)-EDTA complex is slightly or not affected by the presence of vegetable foods or milk. All these data suggest that only a small amount of iron from this salt, about 10 mg/day, would be necessary to prevent iron deficiency anemia even in those populations relying for their subsistence on vegetable food only.

Absorption↗
PubMed2002

Induction of oxidative stress in paraquat formulating workers.

Paraquat as a bipyridyl compound is widely used as an effective herbicide worldwide. In this study, oxidative stress was investigated in blood samples of workers in a pesticide factory, formulating paraquat products for use in agriculture. Controls were age-matched workers with no history of pesticide exposure. They were measured for lipid peroxidation (LPO), antioxidant power and total thiol (SH) groups in blood. The results expressed as mean+/-SD show induction of oxidative stress in workers as revealed by increased plasma LPO (11.46+/-0.99 vs 10.11+/-0.69, P<0.001), decreased plasma antioxidant capacity (1.35+/-0.03 vs 1.54+/-0.05, P<0.001) and plasma SH groups (0.16+/-0.01 vs 0.21+/-0.01, P<0.001) in comparison to those of controls. It is concluded that paraquat-formulating factory workers have elevated LPO and decreased antioxidant power, which may put them in further consequences of oxidative stress.

Adult↗
PubMed2006

Vibrational spectroscopic investigation of structurally-related LiFePO4, NaFePO4, and FePO4 compounds.

Vibrational spectroscopy was utilized to investigate the local structure of LiFePO(4), NaFePO(4), and FePO(4). The factor group splitting of the intramolecular PO(4)(3-) vibrations is between 10 and 20 cm(-1) less for NaFePO(4) than for LiFePO(4). This is because Li(+) ions have a higher charge density than Na(+) ions and can form stronger coordinative bonds with the PO(4)(3-) anions. Thus, the internal modes are more perturbed in LiFePO(4) and exhibit larger factor group splitting effects. The similarity of the factor group multiplets for both LiFePO(4) and NaFePO(4), particularly the PO(4)(3-) bending modes, strongly suggests that the 506 and 470 cm(-1) bands of LiFePO(4) consist almost entirely of lithium translatory motion. There are marked differences between the vibrational spectrum of FePO(4) and those of LiMPO(4) (M=Mn, Fe, Co, or Ni) or NaFePO(4). The monovalent cations interact with the oxygen atoms of the phosphate groups, affecting the frequencies and intensities of the intramolecular PO(4)(3-) modes, in a manner that is absent in FePO(4).

Electrochemistry↗
PubMed2006

Electrocatalytic properties of guanine, adenine, guanosine-5'-monophosphate, and ssDNA by Fe(II) bis(2,2':6',2''-terpyridine), Fe(II) tris(1,10-phenanthroline), and poly-Fe(II) tris(5-amino-1,10-phenanthroline).

The electrocatalytic oxidations of guanine, adenine, guanosine-5'-monophosphate(GMP) and ssDNA were performed in the presence of Fe(II) bis(2,2':6',2''-terpyridine) and Fe(II) tris(1,10-phenanthroline) complexes as homogeneous catalysts by cyclic voltammetric methods. The Fe(II/III) redox couple of these compounds is responsible for their catalytic properties. The electrocatalytic oxidation current of above substrates were developed from the anodic peak currents of Fe(II) bis(2,2':6',2''-terpyridine) and Fe(II) tris(1,10-phenanthroline) complexes at about +0.93 V and 0.97 V, respectively. The electrocatalytic oxidative properties of guanine by Fe(II) bis(2,2':6',2''-terpyridine) complex was measured by amperometry method using the rotating disk electrodes. Electropolymerization of Fe(II) tris(5-amino-1,10-phenanthroline) complex produced thin polymer films on gold and glassy carbon electrodes. The electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry were used to study the in situ growth of the polymer. The poly(FeII(5-NH(2)-1,10-phen)(3)) exhibited a good electrocatalytic oxidation towards guanine and also for the mixture of guanine and adenine too.

Adenine↗
PubMed2005

Identification of alkyl carbazoles and alkyl benzocarbazoles in Brazilian petroleum derivatives.

Carbozoles are important compounds in crude oils, as they may be used as geochemical tracers, being the major type of nitrogen compounds in petroleum. At the same time, they are regarded as undesirable due to the problems they may cause in the refining process, such as catalyst poisoning, corrosion, gum or color formation in final products. As separation and identification of carbazoles are challenging goals, this work presents a chromatographic method, made of a pre-fractionation on neutral alumina followed by the separation and identification of two classes of carbazoles using FeCl(3)/Chromossorb W and gas chromatograph with mass spectrometer (GC/MS) (SIM-single ion monitoring mode) analysis. For the first time, a series of alkyl carbazoles and alkyl benzocarbazoles were identified in heavy gas oil (HGO) and atmospheric residue of distillation (ARD) obtained from Brazilian petroleum.

Aluminum Oxide↗
PubMed2006

Trigonal bipyramidal iron(III) and manganese(III) oxo, sulfido, and selenido complexes. An electronic-structural overview.

Using density functional theory calculations, we have carried out a broad survey of trigonal bipyramidal iron(III) and manganese(III) oxo, sulfido, selenido, and hydroxo complexes, with tripodal tetradentate "triureidoamine" supporting ligands. The calculations reproduce the experimentally observed high-spin states of these compounds; a multifunctional analysis suggests that the high-spin nature of these species follows largely from their trigonal bipyramidal geometry. In conjunction with earlier calculations, the present study provides a broad overview of spin density profiles in iron-oxo species in general. Iron-oxo d(pi)-p(pi) interactions invariably result in a substantial spin density on the oxygen, which in turn may be significantly tuned by hydrogen bonding interactions. The oxygen spin densities are smaller in analogous manganese-oxo species, indicating that manganese is less adept at pi-bonding than iron, which parallels earlier findings on porphyrin systems. The Fe(III)-S/Se spin density profiles provide one of the first confirmations in a transition metal context of Schleyer's prediction that the heavier p-block elements are as effective as their second-row congeners in terms of their pi-donating ability.

Ferric Compounds↗
PubMed2006

Chloroquine inhibits Paracoccidioides brasiliensis survival within human monocytes by limiting the availability of intracellular iron.

The mechanisms used by Paracoccidioides brasiliensis(Pb 18) to survive into monocytes are not clear. Cellular iron metabolism is of critical importance to the growth of several intracellular pathogens, including P. brasiliensis, whose capacity to multiply in mononuclear phagocytes is dependent on the availability of intracellular iron. Chloroquine, by virtue of its basic properties, has been shown to prevent release of iron from holotransferrin by raising endocytic and lysosomal pH, and thereby interfering with normal iron metabolism. Then, in view of this, we have studied the effects of CHLOR on P. brasiliensis multiplication in human monocytes and its effect on the murine paracoccidioidomycosis. CHLOR induced human monocytes to kill P. brasiliensis. The effect of CHLOR was reversed by FeNTA, an iron compound that is soluble at neutral to alkaline pH, but not by holotransferrin, which releases iron only in an acidic environment. CHLOR treatment of Pb 18-infected BALB/c mice significantly reduced the viable fungi recovery from lungs, during three different periods of evaluation, in a dose-dependent manner. This study demonstrates that iron is of critical importance to the survival of P. brasiliensis yeasts within human monocytes and the CHLOR treatment in vitro induces Pb 18 yeast-killing by monocytes by restricting the availability of intracellular iron. Besides, the CHLOR treatment in vivo significantly reduces the number of organisms in the lungs of Pb-infected mice protecting them from several infections. Thus, CHLOR was effective in the treatment of murine paracoccidioidomycosis, suggesting the potential use of this drug in patients' treatment.

Animals↗
PubMed1990

O2- generation and lipid peroxidation during the oxidation of a glycated polypeptide, glycated polylysine, in the presence of iron-ADP.

Oxidation of glycated polylysine, a model compound of glycated protein, caused O2- production even at physiological pH, which could be accelerated by Fe3(+)-ADP. An enediol structure in glycated polylysine and related compounds, which could be confirmed by I2 uptake, was related to their oxidizability. Glycated polylysine was easily coordinated with Fe3+ even in the presence of phosphate at pH 7.4 and the formation of the iron complex was prevented by desferrioxamine. The exposure of unsaturated phospholipid liposomes to glycated polylysine-Fe3(+)-ADP system caused the production of a thiobarbituric acid-reacting substance, which was completely inhibited by 5 microM alpha-tocopherol or 150 microM desferrioxamine and slightly by 0.5 microM SOD. Catalase (20 micrograms/ml) and 10 mM sodium-benzoate did not affect the iron-glycated polylysine-induced lipid peroxidation, indicating no participation of an OH. in this reaction. A ferrous ion-coordinated glycated polylysine may act as an initiator of phospholipid peroxidation in the presence of oxygen. A possible mechanism of the iron-glycated polylysine-induced lipid peroxidation was discussed.

Adenosine Diphosphate↗
PubMed1990

In vitro observations of iron-doped bioactive glasses.

Several in vitro tests are necessary to evaluate the biological compatibility of materials used to manufacture implants for humans or animals. These tests will indicate whether these materials can be tolerated when implanted in vivo. Since ceramic materials are suitable for coating layers, it was decided to study their performance by adding certain oxides as doping agents. This paper describes their influence in vivo in some preliminary tests and in vitro for iron trioxide only. This work attempts to ascertain the range of doping to maintain the bioactivity characteristics and in particular the influence of iron trioxide as a doping agent in the bioactive glass. To do so the adhesion of baby hamster kidney cells to bioactive glasses doped with different concentrations (2 and 4 wt%) of this compound was quantified. The base glass without iron oxide was used as a control as 0 wt% doping. In a second phase, a coating of fibronectin, a glycoprotein that plays an important role in cell binding and spreading on substrates, was quantified on the same surfaces. It was shown that the cell avidity for the surfaces of the materials increases with increased doping of iron oxide. The values are significantly higher than those observed for the base glass. Fibronectin adsorption quantification showed a similar trend, with values of adsorption similar for the doped samples and higher than that of the non-doped glass. It was demonstrated that iron trioxide induces an increase in cell adhesion capability with bioactive glass surfaces and the capability of adhesion of the fibronectin to act as a substrate on the same surfaces.

Adsorption↗
PubMed1997

Feed-back inhibition of oxidative stress by oxidized lipid/amino acid reaction products.

Three oxidized lipid/amino acid reaction products (OLAARPs): 1-methyl-4-pentyl-1,4-dihydropyridine-3,5-dicarbaldehyde, 1-(5-amino-1-carboxypentyl)pyrrole, and N-(carbobenzyloxy)-1(3)-[1-(formylmethyl)hexyl]-l-histidine dihydrate, were prepared and tested for antioxidative activity in a microsomal system in order to investigate the effect that OLAARP formation may be playing in the oxidative stress process. The microsomal system consisted of freshly prepared trout muscle microsomes, which were oxidized in the presence of 5 microM Cu2+, 1 mM Fe3+/5 mM ascorbate, or 1 mM Cu2+/10 mM H2O2, and the compound to be tested as antioxidant added at 50 microM. At different periods of time, samples were tested for lipid peroxidation, assessed by the formation of thiobarbituric acid reactive substances (TBARS), and protein damage, which was evaluated by the formation of protein carbonyls and amino acid analysis. The three OLAARPs and butylated hydroxytoluene significantly (p < 0.05) protected against lipid peroxidation and protein damage for the three systems assayed. On the contrary, neither the amino acids used in the preparation of OLAARPs nor alpha-tocopherol, mannitol, aminoguanidine, or 4, 5-dihydroxy-1,3-benzenedisulfonic acid exhibited this constant protection. Because OLAARPs were produced at inhibitory levels during microsomal lipid peroxidation, these results suggest that OLAARP formation may be an antioxidative defense mechanism by which oxidative stress is feed-back-inhibited, delaying the damage caused by reactive oxygen species.

Alanine↗
PubMed1995

Structure-function relationships for a new series of pyridine-2-carboxaldehyde thiosemicarbazones on ribonucleotide reductase activity and tumor cell growth in culture and in vivo.

The synthesis of a new series of pyridine-2-carboxaldehyde thiosemicarbazones (HCTs) that have amino groups in the 3- and 5-positions has allowed the comparison of the structure/function relationships with regard to inhibition of ribonucleotide reductase activity, L1210 cell growth in culture and L1210 leukemia in vivo. 3-Aminopyridine-2-carboxaldehyde thiosemicarbazones are more active than the corresponding 3-hydroxy-derivatives. The 3-amino-2-pyridine carboxaldehyde thiosemicarbazones were also more active then the 5-amino-2-carboxaldehyde thiosemicarbazones in inhibiting ribonucleotide reductase activity and L1210 cell growth in culture and in vivo. N-Acetylation of the 3-amino derivative resulted in a compound that was much less active both in vitro and in vivo; N-acetylation of the 5-amino derivative did not alter the in vitro inhibitory properties, but did eliminate the antitumor properties in vivo. When the most active HCTs were studied in more detail, it was found that the incorporation of [3H]thymidine into DNA was inhibited completely without the inhibition of [3H]uridine incorporation into RNA. Further, the conversion of [14C]cytidine to deoxycytidine nucleotides and incorporation into DNA was inhibited by the HCTs without an effect on the incorporation of cytidine into RNA. These data support the conclusion that ribonucleotide reductase is the major site of action of these HCTs. The 3-aminopyridine-2-carboxaldehyde thiosemicarbazones emerge as strong candidates for development for clinical trials in cancer patients.

Acetylation↗
PubMed1994

Urinary and biliary excretion of aluminoxamine and ferrioxamine in dogs with various renal function.

We assessed the pharmacokinetics of aluminoxamine and ferrioxamine in dogs with sustained intermittent bile duct ligation and either normal renal function or stable chronic renal failure. A first group of male beagle dogs were given aluminoxamine and ferrioxamine, while a second group received desferrioxamine after loading them with iron and aluminum. Only minute amounts of ferrioxamine and aluminoxamine were found in the bile after administration of these compounds. The distribution volume of aluminoxamine and ferrioxamine appeared to be confined to the extracellular space and their renal excretion correlated with renal function. Administration of desferrioxamine to iron and aluminum-loaded dogs resulted in an increased biliary ferrioxamine but negligible aluminoxamine excretion. Renal clearance of the in vivo formed ferrioxamine and aluminoxamine in this group strongly correlated with renal function. Our observations indicate that biliary excretion of intravenously administered ferrioxamine and aluminoxamine is negligible even in renal failure. The data presented in this study provide indirect evidence that desferrioxamine administration to iron- and aluminum-loaded dogs results in the intra-hepatic formation of ferrioxamine which is partly excreted in the bile. Biliary excretion of aluminoxamine after desferrioxamine administration remained negligible.

Aluminum↗
PubMed2005

Recycling spent zinc manganese dioxide batteries through synthesizing Zn-Mn ferrite magnetic materials.

A novel process to reclaim spent zinc manganese dioxide batteries (SDBs) through synthesizing Zn-Mn ferrite magnetic materials is present. Firstly, the dismantling, watering, magnetism, baking and griddling steps were consecutively carried out to obtain iron battery shells, zinc grains and manganese compounds using the collected SDBs, and then these separated substances were dissolved with 4 mol L(-1) H(2)SO(4) to prepare FeSO(4), ZnSO(4) and MnSO(4) reactant solutions. Secondly, Zn-Mn ferrites with stoichiometric ratio of Mn(0.26)Zn(0.24)FeO(2) were synthesized using chemical co precipitation process with ammonium oxalate precipitator. The XRD results showed that the obtained Zn-Mn ferrites had spinel structure and high purity at the calcining temperatures of 850-1250 degrees C. With the increase of calcining temperature, the finer crystalline structure could be formed, and their intensity of saturation magnetization reached the highest value at 1150 degrees C. The magnetization performances of Zn-Mn ferrites prepared from the SDBs were similar to that of from analysis reagents, suggesting the feasibility to synthesize Zn-Mn ferrites with high properties from SDBs.

Conservation of Natural Resources↗
PubMed2004

Macrophage brain infiltration in experimental autoimmune encephalomyelitis is not completely compromised by suppressed T-cell invasion: in vivo magnetic resonance imaging illustration in effective anti-VLA-4 antibody treatment.

Large inflammatory infiltrates of T cells, macrophages and B cells in the central nervous system (CNS) contribute to the pathogenesis of multiple sclerosis (MS). The passage of T cells through the blood-brain barrier can be suppressed with antibodies directed against alpha-4 integrins (VLA-4) that mediate T-cell adherence. This treatment, in phase III of clinical trial evaluation, reduces lesion development in MS patients. In the ongoing inflammatory disease process the consequences of T-cell inhibitory anti-VLA-4 antibodies on inflammatory compounds are still poorly investigated. We show that anti-VLA-4 antibody treatment during the late preclinical phase of the acute experimental autoimmune encephalomyelitis (EAE) MS rat model interrupts T-cell egress out of the vascular compartment and suppresses clinical disease and histological alterations but macrophage recruitment in the CNS is not fully compromised. Among the treated EAE animals not developing disease, none presented foci of T-cell infiltration in CNS. However, in 75% of the treated EAE rats monocyte ingress in CNS was observed in vivo by magnetic resonance imaging with the ultrasmall superparamagnetic iron oxide contrast agent. Our data shed new light on the role of remaining macrophage brain infiltration in an induced but interrupted T-cell-mediated EAE disease process.

Acute Disease↗
PubMed1995

Subcellular Localization and Characterization of Excessive Iron in the Nicotianamine-less Tomato Mutant chloronerva.

To understand the function of the Fe2+-complexing compound nicotianamine (NA) in the iron metabolism of plants we have localized iron and other elements in the NA-containing tomato wild type (Lycopersicon esculentum) and its NA-free mutant chloronerva by quantitative x-ray microanalysis. Comparison of element composition of the rhizodermal cell walls indicated that the wild type accumulated considerable amounts of iron and phosphorus in the cell wall, whereas in the mutant iron and phosphorus were detected in the cytoplasm and vacuoles of the rhizodermis. In mutant leaves containing high iron concentrations in the symplast, electron-dense inclusions were detected in chloroplasts and phloem. Such particles, consisting mainly of iron and phosphorus, were never found in the wild type and were very rarely detected in young chlorotic mutant leaves or after treatment of the mutant with NA. For further characterization the electron-dense inclusions in mutant leaves were isolated and compared by sodium dodecyl sulfate-gel electrophoresis and immunoblotting to ferritin from iron-loaded Phaseolus vulgaris leaves. Antibodies raised against purified Phaseolus leaf ferritin were used. Neither in mutant nor in wild type (iron loaded and control) was ferritin protein detected. These results suggest that the electron-dense inclusions in mutant leaves are not identical with ferritin. It is concluded that NA is necessary to complex ferrous iron in a soluble and available form within the cells. In the absence of NA the precipitation of excessive iron in the form of insoluble ferric phosphate compounds could protect the cells from iron overload.

Journal Article↗
PubMed2004

Ferritin-induced relaxation in tissues: an in vitro study.

PURPOSE: To study in vitro the proton relaxation induced in tissues by ferritin, the iron-storing protein of mammals. MATERIALS AND METHODS: Nuclear magnetic relaxation dispersion (NMRD) profiles of liver and spleen from control and iron-overloaded mice are compared with NMRD profiles of ferritin and Fercayl-a ferritin-like akaganeite particle-in aqueous solutions or in 1% agarose gel. RESULTS: The relaxation of water protons induced by ferritin and Fercayl in 1% agarose gel is comparable with the relaxation of aqueous solutions of the same compounds, but slower than the relaxation of liver and spleen. The gel is not a good model of tissues containing ferritin. The longitudinal NMRD profiles of control and iron-overloaded liver and spleen are almost identical: ferritin accumulation has only a slight effect on longitudinal relaxation. The transverse NMRD profiles of liver and spleen tissues are linear, but the slope of the linear regression is larger for iron-loaded organs than for control ones, which is a consequence of a higher ferritin concentration in the former. However, the correlation between the slope of the transverse NMRD profiles and the iron concentration is not very good, probably because transverse relaxation is modified by the clustering of ferritin in cells. CONCLUSION: It could be difficult to develop a general technique for the accurate quantification of ferritin-bound iron by nuclear magnetic resonance or magnetic resonance imaging.

Animals↗
PubMed2001

Technical advance: reduction of Fe(III)-chelates by mesophyll leaf disks of sugar beet. Multi-component origin and effects of Fe deficiency.

The characteristics of the Fe(III)-chelate reductase activity have been investigated in mesophyll disks of Fe-sufficient and Fe-deficient sugar beet leaves. The Fe(III)-chelate reductase activity of mesophyll disks was light dependent and increased markedly when the epidermis was removed. Iron(III)-citrate was photo-reduced directly by light in the absence of plant tissue. Total reductase activity was the sum of enzymatic mesophyll reduction, enzymatic reduction carried out by organelles exposed at the disk edge and reduction caused by the release of substances both by exposed mesophyll cells and at the disk edge. Compounds excreted were shown by HPLC to include organic anions, mainly oxalate, citrate and malate. When expressed on a leaf surface basis, Fe deficiency decreased the total mesophyll Fe(III)-chelate reductase activity. However, Fe-sufficient disks reduced less Fe than the Fe-deficient ones when expressed on a chlorophyll basis. The optimal pH values for Fe(III) reduction were always in the range 6.0-6.7. In control leaves Fe(III)-citrate and Fe(III)-malate were the substrates that led to the highest Fe reduction rates. In Fe-deficient leaves Fe(III)-malate led to the highest Fe reduction rates, followed by Fe(III)-EDTA and then Fe(III)-citrate. K:(m) values for the total reductase activity, enzymatic mesophyll reduction and enzymatic reduction carried out by organelles at the disk edge were obtained.

Chenopodiaceae↗