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PubMed1978

Catalases and peroxidases histochemical detection; techniques suitable to discriminate these enzymes.

By using the benzidine reaction, on filter paper strips loaded with catalases, peroxidases, porphyrins, haemic iron compounds and iron salts, it was possible to establish 2 histochemical techniques able to detect and discriminate catalases and peroxidases. Spot test analytical studies show that only peroxidases oxidize benzidine in presence of a 0.0015 M H2O2 final concentration into the incubation medium. If a 0.0035 M H2O2 final concentration is used both peroxidases and haemic iron were able to oxidize benzidine. At a 0.01 M H2O2 final concentration the oxidative property of catalases become apparent and therefore at this H2O2 concentration either peroxidases or haemic iron, as well as catalases could be detected. By increasing the H2O2 concentration into the incubation medium, when a 4M concentration was chosen to detect histochemically catalases without any peroxidases interference. Using 0.0015 M and 4 M H2O2 final concentrations into the incubation medium it is possible to discriminate histochemically catalases and peroxidases. Several inhibitors of catalases and peroxidases were used as an attempt to try a specific inhibition of only one of these enzymes. It was demonstrated that the use of inhibitors does not help the histochemical discrimination between catalases and peroxidases.

Adrenal Glands↗
PubMed2004

Modulation of DMT1 activity by redox compounds.

Iron(II) exacerbates the effects of oxidative stress via the Fenton reaction. A number of human diseases are associated with iron accumulation including ischemia-reperfusion injury, inflammation and certain neurodegenerative diseases. The functional properties and localization in plasma membrane of cells and endosomes suggest an important role for the divalent metal transporter DMT1 (also known as DCT1 and Nramp2) in iron transport and cellular iron homeostasis. Although iron metabolism is strictly controlled and the activity of DMT1 is central in controlling iron homeostasis, no regulatory mechanisms for DMT1 have been so far identified. Our studies show that the activity of DMT1 is modulated by compounds that affect its redox status. We also show that both iron and zinc are transported by DMT1 when expressed in Xenopus laevis oocytes. Radiotracer uptake and electrophysiological measurements revealed that H(2)O(2) and Hg(2+) treatments result in substantial inhibition of DMT1. These findings may have a profound relevance from a physiological and pathophysiological standpoint.

Animals↗
PubMed1976

Isolation, properties and taxonomic relevance of lipid-soluble, iron-binding compounds (the nocobactins) from Nocardia.

Representative strains of the genus Nocardia, when grown on iron-deficient media, produce intracellular lipid-soluble, iron-binding compounds known as nocobactins. However, strains representing the 'rhodochrous' taxon fail to form such compounds. The formation of the nocobactins is completely repressed in bacteria grown on iron-sufficient media. Procedures for purifying the nocobactins are described. From their various properties (u.v. and visible spectra of the the ferri- and desferri-materials, mobility upon thin-layer chromatography, and dissociation patterns in HCl), they can be distinguished from the mycobactins (related compounds from mycobacteria) and divided into three main classes. The classes correspond to the three well-described species of the genus Norcardia: N. asteroides, N. brasiliensis and N. caviae. The correlation of the nocobactin data with previous results of conventional numerical taxonomy is high. Two strains of N. asteroides, however, did not produce nocobactins of the group type.

Azepines↗
PubMed1976

Iron-chelating compound from Mycobacterium avium.

A iron-chelating monohydroxamate was isolated from cultures of Mycobacterium avium grown on an iron-limiting medium. The hydroxyamate metabolite was characterized by chemical degradation and spectral measurements as L-alpha-asparaginyl-L-alpha-(N-hydroxy)-asparagine.

Asparagine↗
PubMed1997

High-Pressure Iron-Sulfur Compound, Fe3S2, and Melting Relations in the Fe-FeS System

An iron-sulfur compound (Fe3S2) was synthesized at pressures greater than 14 gigapascals in the system Fe-FeS. The formation of Fe3S2 changed the melting relations from a simple binary eutectic system to a binary system with an intermediate compound that melted incongruently. The eutectic temperature in the system at 14 gigapascals was about 400°C lower than that extrapolated from Usselman's data, implying that previous thermal models of Fe-rich planetary cores could overestimate core temperature. If it is found in a meteorite, the Fe3S2 phase could also be used to infer the minimum size of a parent body.

Journal Article↗
PubMed1989

Iron-binding compounds produced by wood-decaying basidiomycetes.

The chrome azurol-S universal siderophore assay and the rapid paper electrophoresis siderophore assay were used to screen 10 wood-decaying basidiomycete isolates for the formation of iron-chelating compounds. All 10 isolates were positive for chrome azurol-S reactivity on solid plating medium and in liquid cultures, and 9 of the 10 isolates produced fluorescent iron-binding compounds in the paper electrophoresis assay.

Journal Article↗
PubMed1980

A direct colorimetric method for the determination of phospholipids with dithiocyanatoiron reagent.

A simple and sensitive colorimetric method for the quantitative determination of phospholipids in various kinds of biological materials is described. The method, modification of a previous method using tetrathiocyanatocobaltate, is based on the formation of hydrophobic complexes between dithiocyanatoiron reagent and phospholipids. Under the standard conditions all species of neutral phospholipids, including lysophosphatidylcholine and sphingomyelin, form stable hydrophobic complexes with the iron compound. Although species of acidic phospholipids also have slight affinity for the iron compound, they do not disturb the assay appreciably, because their contents in biological materials are low. Under special conditions, the iron compound reacts only with phosphatidylcholine, and therefore it may also be used for specific determination of this phospholipid.

Colorimetry↗
PubMed2002

Novel chiral three-dimensional iron(III) compound exhibiting magnetic ordering at T(c) = 40 K.

The preparation and crystal structure determination of the iron(III) compound of formula [(NH(4))(2)[Fe(2)O(ox)(2)Cl(2)].2H(2)O](n) (1) (ox = oxalate dianion) are reported here. Complex 1 crystallizes in the orthorhombic system, space group Fdd2, with a = 14.956(7) A, b = 23.671(9) A, c = 9.026(4) A, and Z = 8. The structure of complex 1 consists of the chiral anionic three-dimensional network [Fe(2)O(ox)(2)Cl(2)](2-) where the iron(III) ions are connected by single oxo and bisbidentate oxalato groups. The metal-metal separations through these bridging ligands are 3.384(2) and 5.496(2) A, respectively. Ammonium cations and crystallization water molecules are located in the helical pseudohexagonal tunnels defined by iron atoms. The longest iron-iron distance in the pseudohexagonal tunnel is 15.778(2) A whereas the shortest one is 8.734(2) A. The iron atoms are hexacoordinated: a terminal chloro ligand and five oxygen atoms, that of the oxo group and four from two cis coordinated oxalate ligands, build a distorted octahedral environment around the metal atom. The Fe-O(oxo) bond distance [1.825(2) A] is significantly shorter than the Fe(III)-O(ox) [average value 2.103(4) A] and Fe(III)-Cl bond distances [2.314(2) A]. Magnetic susceptibility measurements of 1 in the temperature range 2.0-300 K reveal the occurrence of a susceptibility maximum at 195 K and a transition toward a magnetically ordered state in the lower temperature region with T(c) = 40 K. The strong antiferromagnetic coupling through the oxo bridge (J = -46.4 cm(-1), the Hamiltonian being H = -JS(A).S(B)) accounts for the susceptibility maximum whereas a weak spin canting of approximately 0.3 degrees due to the antisymmetric magnetic exchange within the chiral three-dimensional network is responsible for the magnetic ordering. The values of coercive field (H(c)) and remnant magnetization (M(r)) obtained from the hysteresis loop of 1 at 5 K are 4000 G and 0.016 micro(B).

Journal Article↗
PubMed2005

Iron absorption by human subjects from different iron fortification compounds added to Thai fish sauce.

OBJECTIVES: (a) To measure iron absorption by human subjects from citric acid stabilized fish sauce fortified with ferrous sulfate, ferric ammonium citrate or ferrous lactate and (b) to identify the effect of added citric acid (3 g/l) on iron absorption from ferrous sulfate fortified fish sauce. DESIGN: Iron absorption from the intrinsically labeled compounds was determined via erythrocyte incorporation of isotopic labels ((57)Fe and (58)Fe) using a randomized crossover design. In three separate absorption studies, 10 adult women each consumed a basic test meal of rice and vegetable soup seasoned with isotopically labeled, iron fortified fish sauce. RESULTS: Iron absorption was significantly lower from ferrous lactate and from ferric ammonium citrate fortified fish sauce than from ferrous sulfate fortified fish sauce. Fractional iron absorption (geometric mean; -1s.d., +1s.d.) was 8.7(3.6; 21.4)% for ferrous lactate compared to 13.0(5.4; 31.4)% from ferrous sulfate, P = 0.003 (study 1) and 6.0(2.5; 14.3)% from ferric ammonium citrate relative to 11.7(4.4; 30.7)% from ferrous sulfate, P < 0.001, in study 2. Citric acid added at a molar ratio of approximately 2.5 to iron had no effect on iron absorption from ferrous sulfate (study 3). Iron absorption in the presence of citric acid was 14.1(6.4; 30.8)% compared to 12.0(5.8; 24.7)% in its absence (P = 0.26). CONCLUSIONS: Iron absorption was 50-100% higher from ferrous sulphate fortified fish sauce than from fish sauce fortified with ferric ammonium citrate or ferrous lactate. In the presence of citric acid as a chelator, ferrous sulfate would appear to be a useful fortificant for fish sauce. SPONSORSHIP: International Atomic Energy Agency (IAEA), Vienna, Austria.

Adolescent↗
PubMed2005

Detection, identification and mapping of iron anomalies in brain tissue using X-ray absorption spectroscopy.

This work describes a novel method for the detection, identification and mapping of anomalous iron compounds in mammalian brain tissue using X-ray absorption spectroscopy. We have located and identified individual iron anomalies in an avian tissue model associated with ferritin, biogenic magnetite and haemoglobin with a pixel resolution of less than 5 microm. This technique represents a breakthrough in the study of both intra- and extra-cellular iron compounds in brain tissue. The potential for high-resolution iron mapping using microfocused X-ray beams has direct application to investigations of the location and structural form of iron compounds associated with human neurodegenerative disorders--a problem which has vexed researchers for 50 years.

Absorptiometry, Photon↗
PubMed1984

The tissue-specific accumulation of hepatic zinc metallothionein following parenteral iron loading.

The synthesis in various tissues of the unique metal-binding protein, metallothionein, can be influenced by the administration of certain trace elements. Zinc and cadmium, both of which bind to metallothionein, are most widely recognized as potent inducers. Preliminary results in our laboratory suggested that iron loading causes a marked accumulation of hepatic zinc metallothionein. We present in this report the effects of parenteral iron administration on metallothionein concentration in various tissues. Male chicks (300-350 g) received (ip) either a single injection (+1 Fe) of iron (10 mg Fe/kg, as FeCl3), two injections (+2 Fe) given 24-hr apart, three injections (+3 Fe) each given 24-hr apart, or an equivalent volume of 0.9% saline (control). Twenty-four hours following the final injection, chicks were killed and tissues analyzed for cytoplasmic zinc and metallothionein (Zn-MT). The parenteral administration of ferric iron, FeCl3, resulted in a marked tissue-specific accumulation of zinc as metallothionein. In chicks given +2 Fe, hepatic Zn-MT increased more than 10-fold with a third injection (+3 Fe) causing no further change. The concentration of Zn-MT in renal and pancreatic tissue was unaffected by iron loading. An increase in hepatic Zn-MT was evident prior to detectable changes in total hepatic iron. The administration of other ferrous iron compounds at a similar rate produced comparable changes in hepatic Zn-MT. Feeding excess dietary iron, however, had no effect on liver Zn-MT levels even though similar hepatic iron concentrations were attained. Our results indicated that parenteral administration, but not feeding, of various iron compounds causes a marked increase in zinc metallothionein, specifically in liver tissue.

Amino Acids↗
PubMed1998

Effects of host iron transport compounds on growth kinetics and outer-membrane protein expression of Bilophila wadsworthia.

Since the environmental iron concentration has emerged as an important attribute in the expression of bacterial virulence, the purpose of this study was to determine the effects of transferrin, lactoferrin, heme compounds, and inorganic iron sources (ferric and ferrous sulfate) on the growth of Bilophila wadsworthia and to study its outer membrane composition when grown under these different simulated in vivo conditions. Lactoferrin, transferrin, hemin and hemoglobin supported full growth of the bacteria in media lacking other iron sources. Bilophila wadsworthia was also capable of growing in the presence of ferrous and ferric sulfate. Profiles obtained by SDS-PAGE showed two iron-regulated outer membrane proteins (IROMPs) of 190 kDa and 88 kDa. The 190 kDa was susceptible to proteinase K cleavage in whole cells, indicating its exposure at the cell surface. These two major IROMPs were expressed in iron-restricted media supplemented with iron-bound organic sources and repressed by the addition of inorganic iron sources.

Journal Article↗