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PubMed1996

Pharmacokinetics of iron(III)-hydroxide sucrose complex after a single intravenous dose in healthy volunteers.

The pharmacokinetics of iron were investigated after intravenous administration to 12 healthy volunteers of iron(III)-hydroxide sucrose complex (Venofer) as a single i.v. dose containing 100 mg Fe. The average predose concentration was 35.7 +/- 12.5 mumol/l. There was no statistically significant difference between the serum iron level before injection (0 h) and the level at 24 h after the injection. The compartment model used includes a Michaelis-Menten term and is in excellent agreement with the observed exchange of iron to transferrin and with the daily iron turnover by transferrin. The intravenously injected iron(III)-hydroxide sucrose complex led rapidly to high serum iron levels. Maximum measured levels averaged 538 mumol/l (30.0 mg/l) at 10 min after the injection. The terminal half-life of the injected iron was calculated to be 5.3 h. Mean total area under the curve (AUC) was 1491 mumol/l h, the mean residence time (MRT) was 5.5 h. The total body clearance was 20.5 ml/min. The volume of distribution of the central compartment (Vc) was 3.21, hence close to the volume of the serum; the volume of distribution at steady state (Vdss) was 7.31; and the volume of distribution during elimination (Vdarea) was 9.21. The calculated amount of iron transported by transferrin was 31.0 +/- 6.6 mg Fe/ 24h. In summary, the data show that the injected iron(III)-hydroxide sucrose complex is quickly cleared from the serum with a terminal half-life of approximately 5-6 h. Renal elimination of iron contributed very little to the overall elimination (in average < 5%). Renal elimination of sucrose averaged about 68 +/- 10% and 75 +/- 11% of the administered dose after 4 h and 24 h, respectively.

Adult↗
PubMed1996

Safety of intravenous injection of iron saccharate in haemodialysis patients.

BACKGROUND: The most frequent i.v. iron preparations used for haemodialysis patients are iron dextran, iron gluconate and iron saccharate. Possible side effects include anaphylactic reactions due to preformed antibodies to dextran or vascular reactions due to unbound iron during treatment with iron gluconate or iron saccharate. METHODS: Four dosage regimens of i.v. iron saccharate therapy were studied: 10, 20, 40 and 100 mg, which were given over a time period of 1 min after the end of the dialysis session. Iron metabolism parameters (serum iron concentrations, transferrin saturation and serum ferritin levels) were measured at 0, 1, 5, 15 and 30 min after application and immediately prior to the next dialysis session. All 18 regular haemodialysis patients studied received recombinant human erythropoietin (rHuEpo). RESULTS: Serum iron levels and transferrin saturation increased significantly following i.v. injection of all doses of iron saccharate. Iron 'oversaturation' of transferrin iron binding did not occur in patients with transferrin levels > 180 mg/dl. However, in patients with transferrin levels < 180 mg/dl the injection of 100 mg iron saccharate resulted in a transferrin saturation of 102.6 +/- 39.5% (two patients with transferrin levels of 87 and 92 mg/dl had transferrin saturation of 119.8 and 149.7%, two patients with transferrin levels of 148 and 171 mg/dl had transferrin saturations of 77.9 and 63.1%, respectively). Serum ferritin levels remained unchanged during the post-injection period and increased by the next dialysis session following injection of 100 mg iron saccharate by 165%. CONCLUSION: It is concluded that intravenous iron saccharate injection (10-100 mg even within 1 min) does not result in 'oversaturation' of transferrin iron binding if serum transferrin levels are > 180 mg/dl (high-risk patients; transferrin < 100 mg/dl). This may explain, at least in part, the minimal side effects observed during the i.v. application of iron saccharate. Low-dose i.v. iron saccharate (10-40 mg) is recommended for iron supplementation of haemodialysis patients. If injection of 100 mg is necessary, serum transferrin level should exceed 180 mg/dl. There is, however, no need for fast i.v. injection during routine iron supplementation.

Adult↗
PubMed1997

The efficiency of fractionated parenteral iron treatment in CAPD patients.

Some chronic renal failure patients respond poorly to recombinant human erythropoietin (rHuEPO). In continuous ambulatory peritoneal dialysis (CAPD) patients, such a poor response may indicate inadequate dialysis or low body iron stores. To correct iron deficiency, once-a-week intravenous iron supplementation is recommended. However, hemodialysis patients receive iron supplements three times a week. This study was designed to compare the efficacy of iron supplementation between once-weekly and twice-weekly regimens. In both groups, rHuEPO doses were similar. Seventeen CAPD patients were studied. All had hemoglobin levels less than 10 g/dL. Ten patients were given 100 mg intravenous iron once weekly, and 7 were given 50 mg intravenous iron twice weekly until a total iron dose of 600 mg was achieved (stage I). The patients were crossed over to receive another 600 mg iron (stage II). Hematocrit increased significantly in patients receiving twice-a-week iron supplementation (+3.8% and 6%) compared to those receiving once-a-week iron supplementation (+1.3% and 1.4%) during stages I and II. The ferritin levels were not different between the groups. In conclusion, rHuEPO is more effective when administered with intravenous iron.

Adult↗
PubMed1998

[Intravenous iron in the treatment of postoperative anemia in surgery of the spine in infants and adolescents].

PURPOSE OF THE STUDY: Spinal fusion surgery often leeds to massive bleeding responsible for anemia in the postoperative period. The aim of this study was to compare the effect of IV iron III hydroxide sucrose complex (Venofer) versus oral iron fumarate administration in postoperative anemia. The efficacy of both treatments was evaluated by comparing hemoglobin level in the postoperative period. METHODS: Two groups of sixteen patients, scheduled for anterior and/or posterior spinal fusion, were compared. Group 1, historical, was treated by supplementation of 10 mg/kg/day oral iron fumarate. Administration was started when hemoglobin level fell below 9 g/100 ml. Group 2 was treated by intravenous iron sucrose complex using same criteria as in group 1 for starting administration. The dosage of iron was individually adapted according to a target hemoglobin level of 13 g/100 ml and to the actual lowest hemoglobin level measured. The total iron deficit was calculated with the following formula: total iron deficit (mg) = 0.24 x body weight (kg) x (target Hb-actual Hb)(g/l). The patients were supplemented by 3 mg/kg/day until the calculated iron deficit was compensated. RESULTS: Both groups were identical regarding age and lowest hemoglobin level reached in the postoperative period. Hemoglobin increased by 0.25 g/day in group 1, and by 0.36 g/day in group 2. In others words, the beneficial effect of IV iron versus oral iron administration was as high as 45 per cent (p = 0.003). CONCLUSION: Intravenous iron therapy as ferric sucrose complex is a new and more effective form of iron therapy than oral iron therapy to restore postoperative hemoglobin after spinal surgery in children.

Administration, Oral↗
PubMed2003

Evaluation of electron-shuttling compounds in microbial ferric iron reduction.

Iron-reducing bacteria can transfer electrons to ferric iron oxides which are barely soluble at neutral pH, and electron-shuttling compounds or chelators are discussed to be involved in this process. Experiments using semipermeable membranes for separation of ferric iron-reducing bacteria from ferric iron oxides do not provide conclusive results in this respect. Here, we used ferrihydrite embedded in 1% agar to check for electron-shuttling compounds in pure and in enrichment cultures. Geobacter sulfurreducens reduced spatially distant ferrihydrite only in the presence of anthraquinone-2,6-disulfonate, a small molecule known to shuttle electrons between the bacterial cell and ferrihydrite. However, indications for the production and excretion of electron-shuttling compounds or chelators were found in ferrihydrite-containing agar dilution cultures that were inoculated with ferric iron-reducing enrichment cultures.

Anthraquinones↗
PubMed2005

Effects of electron transport inhibitors and uncouplers on the oxidation of ferrous iron and compounds interacting with ferric iron in Acidithiobacillus ferrooxidans.

Oxidation of Fe2+, ascorbic acid, propyl gallate, tiron, L-cysteine, and glutathione by Acidithiobacillus ferrooxidans was studied with respect to the effect of electron transport inhibitors and uncouplers on the rate of oxidation. All the oxidations were sensitive to inhibitors of cytochrome c oxidase, KCN, and NaN3. They were also partially inhibited by inhibitors of complex I and complex III of the electron transport system. Uncouplers at low concentrations stimulated the oxidation and inhibited it at higher concentrations. The oxidation rates of Fe2+ and L-cysteine inhibited by complex I and complex III inhibitors (amytal, rotenone, antimycin A, myxothiazol, and HQNO) were stimulated more extensively by uncouplers than the control rates. Atabrine, a flavin antagonist, was an exception, and atabrine-inhibited oxidation activities of all these compounds were further inhibited by uncouplers. A model for the electron transport pathways of A. ferrooxidans is proposed to account for these results. In the model these organic substrates reduce ferric iron on the surface of cells to ferrous iron, which is oxidized back to ferric iron through the Fe2+ oxidation pathway, leading to cytochrome oxidase to O2. Some of electrons enter the uphill (energy-requiring) electron transport pathway to reduce NAD+. Uncouplers at low concentrations stimulate Fe2+ oxidation by stimulating cytochrome oxidase by uncoupling. Higher concentrations lower deltap to the level insufficient to overcome the potentially uphill reaction at rusticyanin-cytochrome c4. Inhibition of uphill reactions at complex I and complex III leads to deltap accumulation and inhibition of cytochrome oxidase. Uncouplers remove the inhibition of deltap and stimulate the oxidation. Atabrine inhibition is not released by uncouplers, which implies a possibility of atabrine inhibition at a site other than complex I, but a site somehow involved in the Fe2+ oxidation pathway.

Acidithiobacillus↗
PubMed2006

Uranium(VI) reduction by Anaeromyxobacter dehalogenans strain 2CP-C.

Previous studies demonstrated growth of Anaeromyxobacter dehalogenans strain 2CP-C with acetate or hydrogen as the electron donor and Fe(III), nitrate, nitrite, fumarate, oxygen, or ortho-substituted halophenols as electron acceptors. In this study, we explored and characterized U(VI) reduction by strain 2CP-C. Cell suspensions of fumarate-grown 2CP-C cells reduced U(VI) to U(IV). More-detailed growth studies demonstrated that hydrogen was the required electron donor for U(VI) reduction and could not be replaced by acetate. The addition of nitrate to U(VI)-reducing cultures resulted in a transitory increase in U(VI) concentration, apparently caused by the reoxidation of reduced U(IV), but U(VI) reduction resumed following the consumption of N-oxyanions. Inhibition of U(VI) reduction occurred in cultures amended with Fe(III) citrate, or citrate. In the presence of amorphous Fe(III) oxide, U(VI) reduction proceeded to completion but the U(VI) reduction rates decreased threefold compared to control cultures. Fumarate and 2-chlorophenol had no inhibitory effects on U(VI) reduction, and both electron acceptors were consumed concomitantly with U(VI). Since cocontaminants (e.g., nitrate, halogenated compounds) and bioavailable ferric iron are often encountered at uranium-impacted sites, the metabolic versatility makes Anaeromyxobacter dehalogenans a promising model organism for studying the complex interaction of multiple electron acceptors in U(VI) reduction and immobilization.

Chlorophenols↗
PubMed1992

Kinetic studies on the formation and decomposition of compounds II and III. Reactions of lignin peroxidase with H2O2.

The present study characterizes the serial reactions of H2O2 with compounds I and II of lignin peroxidase isozyme H1. These two reactions constitute part of the pathway leading to formation of the oxy complex (compound III) from the ferric enzyme. Compounds II and III are the only complexes observed; no compound III* is observed. Compound III* is proposed to be an adduct of compound III with H2O2, formed from the complexation of compound III with H2O2 (Wariishi, H., and Gold, M. H. (1990) J. Biol. Chem. 265, 2070-2077). We provide evidence that demonstrates that the spectral data, on which the formation of compound III* is based, are merely an artifact caused by enzyme instability and, therefore, rule out the existence of compound III*. The reactions of compounds II and III with H2O2 are pH-dependent, similar to that observed for reactions of compounds I and II with the reducing substrate veratryl alcohol. The spontaneous decay of the compound III of lignin peroxidase results in the reduction of ferric cytochrome c. The reduction is inhibited by superoxide dismutase, indicating that superoxide is released during the decay. Therefore, the lignin peroxidase compound III decays to the ferric enzyme through the dissociation of superoxide. This mechanism is identical with that observed with oxymyoglobin and oxyhemoglobin but different from that for horseradish peroxidase. Compound III is capable of reacting with small molecules, such as tetranitromethane (a superoxide scavenger) and fluoride (a ligand for the ferric enzyme), resulting in ferric enzyme and fluoride complex formation, respectively.

Anisoles↗
PubMed2004

Effect of ferric sorbitol citrate (FSC) administration on NF-kappaB in macrophages and spleen cells of rats.

Interaction of iron metabolism and the immune system is complex and pathological changes in one system affect the other. Ferric sorbitol citrate (FSC), non-toxic compound of ferric ions with sorbitol and citrate. has immunomodulatory effect in treated mice. We investigated an effect of FSC on NF-kappaB expression/activation in peritoneal macrophages and spleen cells of rats. TNF-alpha concentrations in sera of control and FSC intraperitoneal (i.p.) treated Wistar rats were measured by ELISA. Furthermore, peritoneal macrophages (PM) were counted and splenocytes were isolated. PM and splenocytes were lysed and their cytoplasmic and nuclear fractions were separated by centrifugation. The influence of FSC on NF-kappaB expression and/or activity as well as expression of its inhibitor IkappaB-alpha was measured by Western blot. 1.5 and three hours after FSC treatment TNF-alpha level in sera was significantly (p < or = 0.05) increased. Activation of transcription factor NF-kappaB in PM was detected three hours after treatment, followed by significant increment in PM number. In splenocytes NF-kappaB was activated six and 48 hours after FSC application. The results indicate that, after i.p. application, FSC acts as a modulator of the immune system activating NF-kappaB in PM. PM consequently secrete TNF-alpha that activates NF-kappaB in splenocytes.

Animals↗
PubMed1994

Structure-function relationship in the serotransferrin: the role of the pH on the conformational change and the metal ions release.

We report experimental evidence that the pH value of the micro-environment of the protein is the key for the conformational changes of transferrin, rather than the ligated for unligated state of the binding sites. The "open" and "closed" conformation of protein, suggested by X-ray crystallography in static condition, is triggered by the pH value and the effect is independent of the metal ion being transported. We propose a simple description of the structure-function relationship that allows this protein to deliver, in particular, iron or aluminum ions in the biological cycle.

Aluminum Compounds↗
PubMed2004

Surface properties and catalytic performance of La(1-x)Sr(x)FeO(3) perovskite-type oxides for methane combustion.

La(1-x)Sr(x)FeO(3) (x=0.0-1.0) perovskites were prepared and tested for the combustion of methane. X-ray diffraction (XRD) patterns revealed the presence of a single perovskite structure for substitutions 0x0.3, however Fe(2)O(3), SrCO(3) and SrFeO(3) phases were observed for substitutions x>0.3. The results of activity test indicate that with La(1-x)Sr(x)FeO(3) as the catalyst, the combustion of methane can take place at low temperatures around 400 degrees C. Partial substitution of La with Sr increases the activity and an optimal substitution fraction (x=0.5) exists in the La(1-x)Sr(x)FeO(3) catalysts. Catalyst activity can be well correlated to the product of the specific surface area and atomic ratio of Fe to La+Sr on the catalyst surface. Experimental results of O(2)-TPD and CH(4)-TPD in the range of 350-500 degrees C indicate that the amount of oxygen desorbed from the La(1-x)Sr(x)FeO(3) catalysts is far larger than that of methane. Therefore, it can be proposed that the catalytic oxidation of CH(4) over these catalysts proceeds with the surface reaction between CH(4) in the gas phase and the adsorbed O(2). Addition of water vapor or CO(2) to the feed inhibited catalyst activity, but the inhibition was reversible and became negligible at high reaction temperature.

Calcium Compounds↗
PubMed2002

The effect of Ca/P concentration and temperature of simulated body fluid on the growth of hydroxyapatite coating on alkali-treated 316L stainless steel.

316L-SS is one of the important materials both in orthopaedics and dentistry for bone screw/plate, intra-medullary rod, fixation wire, HIP joint, and knee joint. However, the biocompatibility and bone-bonding ability troubled researches for years. In the study, a simple chemical method was tried so as to establish and induce a bioactive HA layer on the surface of 316L stainless steel. When the metallic substrates treated with 10 M NaOH aqueous solution and subsequently heated at 600 degrees C, a thin sodium chromium oxide layer was formed on the surfaces as the linking layer for HA and 316L-SS. After 316L-SS treated with alkali solution, it would soak into a simulated body fluid with higher concentration of calcium and phosphorous ions to increase the possibility of nucleation of HA. However, the iron oxide and iron chromium oxides were formed on the surface when calcium and phosphorous ions increased. This resulted in loosening the HA layer. When the alkali-treated 316L-SS was soaked into SBF at a temperature of 80 degrees C, it could form a dense and uniform bone-like hydroxyapatite layer on the surface. In the research, the mechanism of the formation of sodium chromium oxide and HA would also be described by the analysis of X-ray diffractometer, scanning electron microscope, energy-dispersion spectrophotometer, and Fourier transformation infrared.

Alkalies↗
PubMed2006

Thermospectroscopic study of the adsorption mechanism of the hydroxamic siderophore ferrioxamine B by calcium montmorillonite.

The behavior of iron-chelating agents in soils is highly affected by interactions with the solid phase. Still this aspect is frequently ignored. In this research the adsorption of the siderophore ferrioxamine B by Ca-montmorillonite, as a free ligand (desferrioxamine B, DFOB) and as a complex with Fe3+ (ferrioxamine B, FOB), was studied, using thermo X-ray diffraction (thermo-XRD) in the temperature range 25-360 degrees C and thermo-FTIR spectroscopy in the temperature range 25-170 degrees C. The effect of pH (4-7.5) on the adsorption was examined. Extensive use of curve-fitting analysis was required due to significant overlapping of the characteristic absorption bands of the various functional groups. Thermo-XRD analysis showed that both DFOB and FOB penetrated into the interlayer space of Ca-montmorillonite. FTIR results indicated strong interactions of DFOB within the interlayer, which involved all functional groups (NH3+, secondary amide groups, and hydroxamate groups). In contrast, the folded Fe complex of FOB retained its molecular configuration upon adsorption, and the basal spacing of the clay increased correspondingly. FOB interacted in the interlayer space of the clay, mainly through the NH of the secondary amide groups and NH3+, while the functional groups bound to the central Fe cation remained unchanged. The suspension pH had no significant effect on both DFOB and FOB adsorption at the examined range. Adsorption protected the adsorbates from thermal degradation compared to the nonadsorbed samples up to 105 degrees C. At 170 degrees C both DFOB and FOB were already partially degraded, but to a lesser extent than the nonadsorbed samples. Degradation of the molecules occurred mainly through the hydroxamic groups, which constitute the Fe-chelating center in the hydroxamic siderophore.

Adsorption↗
PubMed2006

Reaction route control by microperoxidase-9/CTAB micelle ratios.

Microperoxidases (MP) as water-soluble models attract interest to studying the reaction mechanism of peroxidases because these heme peptides are able to form the same enzyme intermediates during the reaction with peroxides. In this work we have demonstrated that the association of Fe(III)MP-9 and Fe(III)MP-11 with CTAB micelles (MP-9/CTAB and MP11/CTAB) provides a microenvironment with an alkaline interface and a hydrophobic core that exhibits peroxidase behavior. This microenvironment shifts positively the redox potential of microperoxidases by approximately 100 mV. tert-Butylhydroperoxide (t-BuOOH) when added to the medium, converted Fe(III)MP-9/CTAB to MP-9/CTAB Compound II, a high valence oxidized intermediate of the heme peptide. Subsequent addition of diphenylacetaldehyde (DPAA) to MP-9/CTAB Compound II regenerated the native form of the enzyme, Fe(III)MP-9/CTAB, what characterizes the occurrence of a peroxidase cycle. Fe(III)MP-9/CTAB regenerated during the peroxidase cycle reacted with residual DPAA in the medium to form Fe(II)MP-9/CTAB, which indicates that both Fe(III)MP-9/CTAB and its oxyferryl form can use aldehydes as reducing agents. According to the determined reduction potential, Fe(III)MP-9 and Fe(III)MP-9/CTAB should be able to oxidize DPAA (reduction potential -630 mV). The reaction of MP-9/CTAB with DPAA produced benzophenone as final product, detected by infrared spectroscopy and mass spectrometry. Interestingly, a significant difference was observed in the benzophenone yield according to the micelle/MP-9 molar ratio.

Aldehydes↗