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PubMed1992

The reducing activity of S-aminoethylcysteine ketimine and similar sulfur-containing ketimines.

S-aminoethylcysteine ketimine and other sulfur-containing similar ketimines reduce molecular oxygen and phospho-18-tungstate (Folin Marenzi reagent), although the sulfur atom is formally present in the non reducing thioether form. We have now found that 2,6-diclorophenolindophenol, some ferrihemoproteins and other reagents are also reduced by this group of ketimines. Ferricytochrome c is reduced faster than methemoglobin, metmyoglobin and free hematin, whereas horse radish peroxidase compound I is reduced at once. These results indicate a wider reducing activity of this type of ketimine. The oxidation of ketimines by ferric cytochrome c appears a relevant finding pointing to a new possible way of enzymatic modification of sulfur-ketimines in tissues.

2,6-Dichloroindophenol↗
PubMed2005

Response of mouse skin to tattooing: use of SKH-1 mice as a surrogate model for human tattooing.

Tattooing is a popular cosmetic practice involving more than 45 million US citizens. Since the toxicology of tattoo inks and pigments used to formulate tattoo inks has not been reported, we studied the immunological impact of tattooing and determined recovery time from this trauma. SKH-1 hairless mice were tattooed using commercial tattoo inks or suspensions of titanium dioxide, cadmium sulfide, or iron oxide, and sacrificed at 0.5, 1, 3, 4, 7, or 14 days post-tattooing. Histological evaluation revealed dermal hemorrhage at 0.5 and 1 day. Acute inflammation and epidermal necrosis were initiated at 0.5 day decreasing in incidence by day 14. Dermal necrosis and epidermal hyperplasia were prominent by day 3, reducing in severity by day 14. Chronic active inflammation persisted in all tattooed mice from day 3 to 14 post-tattooing. Inguinal and axillary lymph nodes were pigmented, the inguinal being most reactive as evidenced by lymphoid hyperplasia and polymorphonuclear infiltration. Cutaneous nuclear protein concentrations of nuclear factor-kappa B were elevated between 0.5 and 4 days. Inflammatory and proliferative biomarkers, cyclooxygenase-1, cyclooxygenase-2, and ornithine decarboxylase protein levels were elevated between 0.5 and 4 days in the skin and decreased to control levels by day 14. Interleukin-1 beta and interleukin-10 were elevated in the lymph nodes but suppressed in the tattooed skin, with maximal suppression occurring between days 0.5 and 4. These data demonstrate that mice substantially recover from the tattooing insult by 14 days, leaving behind pigment in the dermis and the regional lymph nodes. The response seen in mice is similar to acute injury seen in humans, suggesting that the murine model might be a suitable surrogate for investigating the toxicological and phototoxicological properties of ingredients used in tattooing.

Animals↗
PubMed1979

Simple metallic compounds as pulp-capping agents.

A study is described in which six metallic compounds identified in a previous pilot experiment were tested as pulp-capping agents using the exposed rat molar. Barium sulfate, calcium carbonate, cupric oxide, ferric oxide, and heavy magnesium oxide gave poor results. Stannic oxide gave more favorable results and is being studied further.

Animals↗
PubMed2000

Halocarbons produced by natural oxidation processes during degradation of organic matter.

Volatile halogenated organic compounds (VHOC) play an important role in atmospheric chemical processes-contributing, for example, to stratospheric ozone depletion. For anthropogenic VHOC whose sources are well known, the global atmospheric input can be estimated from industrial production data. Halogenated compounds of natural origin can also contribute significantly to the levels of VHOC in the atmosphere. The oceans have been implicated as one of the main natural sources, where organisms such as macroalgae and microalgae can release large quantities of VHOC to the atmosphere. Some terrestrial sources have also been identified, such as wood-rotting fungi, biomass burning and volcanic emissions. Here we report the identification of a different terrestrial source of naturally occurring VHOC. We find that, in soils and sediments, halide ions can be alkylated during the oxidation of organic matter by an electron acceptor such as Fe(III): sunlight or microbial mediation are not required for these reactions. When the available halide ion is chloride, the reaction products are CH3Cl, C2H5Cl, C3H7Cl and C4H9Cl. (The corresponding alkyl bromides or alkyl iodides are produced when bromide or iodide are present.) Such abiotic processes could make a significant contribution to the budget of the important atmospheric compounds CH3Cl, CH3Br and CH3I.

Atmosphere↗
PubMed1995

Phosphoric acid tooth conditioner containing copper salt for bonding MMA-TBB resin.

The purpose of this study was to examine the feasibility of a conditioner for treating enamel and dentin simultaneously for MMA-TBB resin bonding. Various phosphoric acid solutions containing copper salts were prepared and used as conditioners before bonding MMA-TBB resin to bovine teeth. Their effects on the surface morphology and bonding were studied by scanning electron microscopy and tensile bond strength testing. The concentrations of phosphoric acid as well as copper salts therein affected the bond strength to dentin. Ten percent phosphoric acid containing 3% copper (II) chloride appeared optimal for treating dentin and was significantly effective in improving the bond strength compared with phosphoric acid alone. This conditioner was applicable also to enamel without any adverse effect on the bond strength. Therefore, enamel and dentin may effectively be treated simultaneously with this conditioner before bonding of MMA/TBB-based resin.

Acid Etching, Dental↗
PubMed1990

Iron (III) hydroxamate transport into Escherichia coli. Substrate binding to the periplasmic FhuD protein.

Due to its extreme insolubility, Fe3+ is not transported as a monoatomic ion. In microbes, iron is bound to low molecular weight carriers, designated siderophores. For uptake into cells of Escherichia coli Fe3+ siderophores have to be translocated across two membranes. Transport across the outer membrane is receptor-dependent and energy-coupled; transport across the cytoplasmic membrane seems to follow a periplasmic binding protein-dependent transport mechanism. In support of this notion we demonstrate specific binding of the Fe3+ hydroxamate compounds ferrichrome, aerobactin, and coprogen, which are transported via the Fhu system, to the periplasmic FhuD protein, and no binding of the transport inactive ferrichrome A, ferric citrate, and iron sulfate. About 10(4) ferrichrome molecules were bound to the FhuD protein of cells which overproduced plasmid-encoded FhuD. Binding depended on transport across the outer membrane mediated by the FhuA receptor and the TonB protein. Binding to FhuD was supported by the exclusive resistance of FhuD to proteinase K in the presence of the transport active hydroxamates. The overproduced precursor form of the FhuD protein was not protected by the Fe3+ hydroxamates indicating a conformation different to the mature form. The FhuD protein apparently serves as a periplasmic carrier for Fe3+ hydroxamates with widely different structures.

Bacterial Proteins↗
PubMed2003

Suppressive effects of Active Hexose Correlated Compound on the increased activity of hepatic and renal ornithine decarboxylase induced by oxidative stress.

Active Hexose Correlated Compound (AHCC), an extract derived from fungi of Basidiomycetes family has been shown to act as a biological response modifier in various disorders. In our present study, ferric nitrilotriacetate (Fe-NTA), which generates hydroxyl radicals in vivo, was given intraperitoneally to rats and AHCC was tested for its ability to suppress oxidative stress and the activity of ornithine decarboxylase (ODC) in the liver and kidney. Substantial increments in glutathione-related enzymes including glutathione reductase, glutathione peroxidase activity as well as oxidized glutathione contents were shown in the liver at 12 h after treatment with Fe-NTA (7.5 mg Fe/kg body weight). Effects of oxidative stress induced by Fe-NTA were also demonstrated by the increase in serum lipid peroxidation, aminotransferases and urinary 8-hydroxy-2'-deoxyguanosine. However, the increases in these parameters were restored to normal in AHCC-pretreated rats. The ODC activity in the liver and kidney was significantly increased by Fe-NTA, while the increased ODC activity induced by Fe-NTA was normalized in AHCC-pretreated rats. These results suggest AHCC acts as a potent antioxidant and protects against disorders induced by oxidative stresses.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1980

Iron acquisition by Neisseria meningitidis in vitro.

Assays employing iron-limited solid and liquid, defined and complex media were devised to test the iron requirements of Neisseria meningitidis. A variety of tests yielded no evidence for the secretion of a soluble iron-binding substance (siderophore) by the meningococci. The meningococci were unable to use iron bound to some common hydroxamate- and catechol-type siderophores or even compete with them for iron in the growth medium. A total of 20 strains of meningococci, differing widely in their virulence for mice, were similar in ability to acquire iron from a variety of iron-containing substances; the iron in such compounds as hog gastric mucin, citrate, hemoglobin, and myoglobin was easily acquired, whereas the iron in compounds such as ferrioxamine B, ferrichrome,ferritin, Imferon, cytochrome c, FePO4, and [Fe(OH)3]n was not readily available. No correlation was noted between the ability of particular strains to obtain iron from compounds and virulence in mice. Iron complexed or chelated with a number of metabolic organic acids, polyphosphates, and several synthetic polycarboxylic acids was readily available to all strains, even though some of the compounds used had high effective binding constants for iron and all were in 3- or 10-fold molar excess over the iron present. The addition of some of these iron-complexing substances (e.g., citrate and pyrophosphate) in iron-free form made many biologically important iron compounds that are normally inaccessible to the meningococci readily available.

Animals↗
PubMed1979

Inhibition of drug oxidation and stimulation of NADPH oxidase in vitro by doxorubicin and triferric-doxorubicin.

The electrophilic properties of the quinone-hydroquinone configuration of anthracycline antibiotics suggests a possible influence on cytochrome P-450-mediated mono-oxygenase reactions. Both doxorubicin and triferric-doxorubicin (a derivative in which the quinone groups are blocked with iron) showed a similar dose-dependent inhibition of liver microsomal drug metabolism. A doxorubicin concentration-related stimulation of NADPH oxidase activity was found to be linear but that for triferric-doxorubicin was asymptotic. Neither inhibitor affected the activity of cytochrome c reductase, cytochrome b5 reductase or cytochrome P-450 reductase. However, doxorubicin did potentiate the inhibitory effect of aniline on cytochrome P-450 reductase and on ethylmorphine metabolism. It is concluded that these anthracyclines inhibit drug metabolism in vitro not by their electron-withdrawing potential but in a manner more similar to that described for type II compounds.

Aminophenols↗
PubMed2000

Investigation of the stability of hardened slag paste for the stabilization/solidification of wastes containing heavy metal ions.

We have studied the effect of chromium ions and lead ions on the chemical stability of hardened slag paste with toxic wastes during the stabilization/solidification process. The influences of Cr and Pb ions on the hydration of slag were also investigated. Sodium silicate (Na(2)SiO(3)), 5 wt.% of slag, was used as an alkali activator for slag hydration. The physical stability of hardened paste containing partial replacement of slag with fly ash and gypsum was also examined. When gypsum was added to slag, the compressive strength of hardened slag paste developed, accompanying the activation of alumino-ferrite-tricalciumsulfate (Al(2)O(3)-Fe(2)O(3)-3CaSO(4), AFt) and alumino-ferrite-monocalciumsulfate (Al(2)O(3)-Fe(2)O(3)-CaSO(4), AFm) phase generation. Those phases caused densification of the microstructure. Concurrently, the leaching amount of heavy metal ions was decreased. When fly ash was added to slag, the compressive strength increased and the leaching amount decreased with both active formation of aluminate hydrates and ion substitution. Lead ions were mostly stabilized through physical encapsulation by the hardened slag paste's hydrate matrix. In the case of chromium ions, we observed that it was mainly solidified through the formation of a substitutional solid solution with aluminum atoms in the structure of aluminate hydrates.

Alkalies↗
PubMed1998

Use of 2-isocyanatoethyl methacrylate and iron (II) perchlorate for bonding tri-n-butylborane-initiated luting agents to dentin.

The present study investigated the effect of 2-isocyanatoethyl methacrylate (IEM) and iron (II) perchlorate on dentin adhesion. Four primers were evaluated, consisting of aqueous 2-hydroxyethyl methacrylate (HEMA) solutions containing 5, 10, 20 or 50 micromol/g iron (II) perchlorate. Five luting agents were prepared with methyl methacrylate (MMA), poly(methyl methacrylate) (PMMA), tri-n-butylborane (TBB) initiator and IEM. The concentrations of IEM in the luting agents were 0.2, 0.4, 0.8, 2.0 and 4.0 wt%. Extracted bovine teeth were ground to expose the dentin, etched with an aqueous solution of 10 wt% phosphoric acid, primed, and then bonded with stainless-steel rods; tensile bond strengths were determined after 1 d immersion in water. The highest bond strength (20.7 MPa) was recorded for the group using 10 micromol/g iron (II) perchlorate and 2.0 wt% IEM. The use of IEM was effective in decreasing the optimal concentration of iron (II) perchlorate, and this may contribute to the color stability of iron-containing pretreatment agents.

Acid Etching, Dental↗
PubMed1989

Iron metabolism of Escherichia coli studied by Mössbauer spectroscopy and biochemical methods.

To date it has barely been recognized that the nature of about 75% of the Escherichia coli iron pool is unknown. Here we report the isolation of two iron species representing major components of iron metabolism in various growth states of E. coli. In vivo Mössbauer spectroscopy was applied to obtain information on the intracellular distribution pattern of iron in E. coli K12 W3110. Only two types of iron could be detected in the cell spectra: hexacoordinated Fe2+ and Fe3+ high-spin complexes. Other iron-requiring compounds are at least one order of magnitude less abundant in E. coli. The Mössbauer parameters of these complexes fit neither cytochromes nor iron-sulfur proteins nor ferric holo-bacterioferritin. They are sensitive to metabolic changes and inhibitors. The ratio of Fe/subunit, Fe2+/Fe3+ interconversion, chromatographic and electrophoretic data exclude bacterioferritin as the main iron metabolite in E. coli. Bacterioferritin can be observed only at very high ferric ion concentrations in the medium. The 55Fe fluorograms of both cytoplasmic and membrane fractions exhibit two exclusive bands with apparent molecular masses of 17 and 15 kDa, respectively. The two bands comprised 70% of the applied radioactivity. In gel filtration the main iron peak elutes at 155 kDa yielding two bands with apparent molecular masses of 17 and 15 kDa on SDS/PAGE. We therefore conclude that the iron species form a protein with an apparent molecular mass of 155 kDa containing 17-kDa and 15-kDa subunits. The iron content of the protein is 44 micrograms Fe/mg protein which corresponds to approximately 13 iron ions/subunit. No iron protein exhibiting the observed features has been described so far. Additional Mössbauer experiments suggest that these novel iron proteins are not restricted to E. coli but that similar components are detectable in several bacterial and fungal systems, thus pointing to a general occurrence.

Bacterial Proteins↗
PubMed1998

New chelate-forming polymer microspheres carrying dyes as chelators for iron overload.

Dye-incorporated [poly(EGDMA-HEMA)] microspheres were investigated as a new chelate-forming polymer for iron overload. Poly(EGDMA-HEMA) microspheres, in the size range of 150-200 microm, were produced by a modified suspension polymerization of EGDMA and HEMA. The reactive dye-ligands (i.e. Cibacron Blue F3GA, Alkali Blue 6B and Congo Red) were covalently incorporated to the microspheres. The maximum dye incorporations were 16.5 micromol Cibacron Blue F3GA g(-1), 23.7 micromol Alkali Blue 6B g(-1), and 14.5 micromol Congo Red g(-1). The maximum Fe(III) adsorptions on the dye-incorporated microspheres from aqueous solutions containing different amounts of Fe(III) ions were 51.0, 37.3, and 25.1 mg g(-1) for the Cibacron Blue F3GA, Alkali Blue 6B, and Congo Red carrying microspheres, respectively. The maximum Fe(III) adsorptions were observed at pH 4.0 in all cases. Fe(III) removal from human plasma was also investigated. The maximum adsorption capacities of Fe(III) ions from human plasma for Cibacron Blue F3GA, Alkali Blue 6B, and Congo Red, were of 12.0, 7.5, and 3.8 mg g(-1) polymer, respectively. It was observed that Fe(III) could be repeatedly adsorbed and desorbed without significant loss in adsorption capacity.

Adsorption↗
PubMed1995

The antioxidant and prooxidant activity of some B vitamins and vitamin-like compounds.

The antioxidant and prooxidant properties of some B vitamins (BVIT) and vitamin-like compounds (VLC) that are commonly included in multivitamin preparations were investigated. Microsomal lipid peroxidation induced by FeCl3 and ascorbate was dose-dependently inhibited by pyridoxal and pantothenate but was stimulated by thiamin, pyridoxine and carnitine. Among the compounds tested, only pyridoxine and pyridoxal reacted, but rather poorly, with superoxide anions. All test compounds reacted with .OH with second-order rate constants comparable or higher than that for mannitol, as assayed using deoxyribose oxidation by a system containing EDTA-chelated Fe(III), H2O2 and ascorbate. When assayed in the absence of EDTA, pyridoxal showed increased inhibition of deoxyribose oxidation over that in the presence of EDTA, suggesting a potent ability of pyridoxal to bind and deactivate iron. Pantothenate, pyridoxine and myo-inositol appeared to equally inhibit deoxyribose oxidation both in the presence and absence of EDTA. The lack of inhibition on deoxyribose oxidation in the absence of EDTA by thiamin, carnitine and choline may suggest that the .OH-scavenging ability is equalled by the ability of the scavenger-iron complexes to form .OH or other redox active species. However, stimulation of lipid peroxidation by pyridoxine was unexplained and the effect was not attributed to reduction of Fe(III) to Fe(II). This study shows that the radical-scavenging ability of BVIT and VLC did not correlate with their effects on microsomal lipid peroxidation. Moreover, the stimulation of lipid peroxidation by thiamin, pyridoxine and carnitine suggests that supplementation of large amounts of these compounds may not be desirable.

Animals↗
PubMed1992

Investigation of Fe(III) chloride as a colour reagent for the spectrophotometric determination of bumetanide in the pure form and in preparations.

The formation and stability of the complex between bumetanide (3-butylamino-4-phenoxy-5-sulphamoylbenzoic acid) and Fe(III) ion was studied. It has been found that bumetanide reacts with Fe(III) chloride in the presence of ammonium thiocyanate at the pH 1.83-1.92 to form a violet complex soluble in chlorophorm, with the maximum absorbance at 514.5 nm. At the optimum experimental conditions the conditional stability constant of the complex was found to be log K' = 7.34. The Beer's law was obeyed up to the 160 microg x cm(-3) and the relative standard deviation varied from 0.406% to 0.475% (n = 10). The proposed method was found to be suitable for the accurate and sensitive analysis of bumetanide as a pure compound and from tables and ampoules.

Bumetanide↗
PubMed1987

The role of hydroxyl radicals in irreversible inactivation of lactoperoxidase by excess H2O2. A spin-trapping/ESR and absorption spectroscopy study.

H2O2 is catalytically metabolized by ferric lactoperoxidase (LPO)----compound (cpd) I----cpd II----ferric LPO cycles. An excess of the substrate, however, is degraded by a ferric LPO----cpd I----cpd II----cpd III----ferrous LPO----ferric LPO cycle. This latter pathway leads to the partial or total irreversible inactivation of the enzyme depending on the excess of H2O2 (H. Jenzer, W. Jones, and H. Kohler (1986) J. Biol. Chem. 261, 15550-15556). Spin-trapping/ESR data indicate that in the course of the reaction superoxide (HO2./O2-) and hydroxyl radicals (OH.) are formed. Since many substances known to scavenge radicals, such as a spin trap (e.g., 5,5-dimethyl-1-pyrroline-N-oxide) desferrioxamine, albumin, or mannitol, do not prevent enzyme inactivation, we conclude that OH. generation is a site-specific reaction at or near the active center of LPO where bulky scavenger molecules may not be able to penetrate. We suggest the formation of OH. by a Fenton-like reaction between H2O2 and the intermediate ferrous state of the enzyme, which substitutes for Fe2+ in the Fenton reaction. OH. is a powerful oxidant which in turn may attack rapidly the nearest partner available, either H2O2 to produce HO2. and H2O, or the prosthetic group to give rise to oxidative cleavage of the porphyrin ring structure of the heme moiety of LPO and thus to the liberation of iron.

Electron Spin Resonance Spectroscopy↗
PubMed2004

Sorption of the herbicide dichlobenil and the metabolite 2,6-dichlorobenzamide on soils and aquifer sediments.

The worldwide used herbicide dichlobenil (2,6-dichlorobenzonitrile) has resulted in widespread presence of its metabolite 2,6-dichlorobenzamide (BAM) in pore- and groundwater. To evaluate the transport of these compounds we studied the sorption of dichlobenil and BAM in 22 sediment samples of clayey till, sand, and limestone including sediments exhibiting varying oxidation states. Dichlobenil sorbed to all investigated sediments, with a high sorption in topsoils (Kd = 7.4-17.4 L kg(-1)) and clayey till sediments (Kd = 2.7-126 L kg(-1)). The sorption of the polar metabolite BAM was much lower than the sorption of dichlobenil but followed the same tendency with the highest sorption in the topsoils (Kd = 0.24-0.66 L kg(-1)) and in the clayey till sediments (Kd = 0.10-0.93 L kg(-1)). The sorption of both compounds was significantly higher (2-47 times) in the unoxidized (reduced) clayey till than in the weathered (oxidized) clayey till. Such a difference in sorption capacity could neither be explained by a higher organic carbon content, sorption to clay minerals, differences in clay mineralogy, nor by blocking of reactive surface sites on clay minerals by iron oxides. However, by removing an average of 81% of the organic carbon from the reduced clayey till with H2O2, the sorption decreased on average 50%. Therefore, most of the sorption capacity in the reduced clayey till was related to organic carbon, which indicates that sorption processes are affected by changes in organic compound composition due to weathering.

Adsorption↗