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PubMed2006

[Analysis of the characteristics of corrosion scale in drinking water distribution systems].

Scanning electron microscopy, X-ray fluorescence spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy were used to analyze the microstructure, chemical composition, crystalline structure and compound constitute of the corrosion scale from cast iron pipe and galvanized steel pipe in drinking water distribution systems. The outer of the corrosion scale was compact, while the inner was porous. Iron was the primary chemical element of the corrosion scale, and the composition of the scale was iron compounds. The outer scale were ferric compounds such as alpha-FeOOH, gamma-FeOOH, alpha-Fe2O3, gamma-Fe2O3, FeCl3, while the inner were ferrous compounds such as Fe3O4, FeCl2, FeCO3. The characteristics of the corrosion scale was lying on hydraulic conditions and water quality in distribution systems, and the characteristics of iron pipe materials.

Corrosion↗
PubMedDate not supplied

Hepatic heme synthesis in a new model of experimental hemochromatosis: studies in rats fed finely divided elemental iron.

Rats fed chow containing finely divided elemental iron (from carbonyl-iron) develop hepatic iron overload resembling human hereditary hemochromatosis in that deposition of iron is primarily in periportal hepatocytes and with hepatic iron concentrations sufficiently high to be associated in the human disease with hepatic fibrosis or cirrhosis. In recent studies using this model, we reported changes in hepatic hemoproteins and heme oxygenase, the rate-controlling enzyme of heme breakdown. We now report effects of iron-loading on three enzymes of heme synthesis: 5-aminolevulinate synthase; the first and rate-controlling enzyme of the pathway, 5-aminolevulinate dehydrase (or porphobilinogen synthase), and uroporphyrinogen decarboxylase, the activity of which is decreased in porphyria cutanea tarda, a liver disease in which iron is known to play an important but still poorly understood role. Of the three enzymes, only activity of the dehydrase was altered by iron-loading: it was decreased significantly as early as 1 week after starting iron feeding, and with marked iron overload was 30 to 32% of control values. The degree of decrease was inversely related (r = -0.77 to -0.88) to the degree of iron overload and was partially reversed within 1 to 3 days when feeding of the iron-supplemented diet was stopped. The decrease in dehydrase activity was not attributable to lack of reduced glutathione or other disulfide-reducing agents or to zinc deficiency; nor was evidence found for inhibition by iron compounds or other possible inhibitors present in iron-loaded livers.(ABSTRACT TRUNCATED AT 250 WORDS)

5-Aminolevulinate Synthetase↗
PubMed2002

Fortification: overcoming technical and practical barriers.

The main barriers to successful iron fortification are the following: 1) finding an iron compound that is adequately absorbed but causes no sensory changes to the food vehicle; and 2) overcoming the inhibitory effect on iron absorption of dietary components such as phytic acid, phenolic compounds and calcium. These barriers have been successfully overcome with some food vehicles but not with others. Iron-fortified fish sauce, soy sauce, curry powder, sugar, dried milk, infant formula and cereal based complementary foods have been demonstrated to improve iron status in targeted populations. The reasons for this success include the use of soluble iron such as ferrous sulfate, the addition of ascorbic acid as an absorption enhancer or the use of NaFeEDTA to overcome the negative effect of phytic acid. In contrast, at the present time, it is not possible to guarantee a similar successful fortification of cereal flours or salt. There is considerable doubt that the elemental iron powders currently used to fortify cereal flours are adequately absorbed, and there is an urgent need to investigate their potential for improving iron status. Better absorbed alternative compounds for cereal fortification include encapsulated ferrous sulfate and NaFeEDTA, which, unlike ferrous sulfate, do not provoke fat oxidation of cereals during storage. Encapsulated compounds also offer a possibility to fortify low grade salt without causing off-colors or iodine loss. Finally, a new and useful additional approach to ensuring adequate iron absorption from cereal based complementary foods is the complete degradation of phytic acid with added phytases or by activating native cereal phytases.

Biological Availability↗
PubMed2001

Mössbauer study of atmospheric aerosols of Shanghai.

Three iron-containing atmospheric aerosol samples were collected, one at a tunnel, one near a viaduct, and one at a park in Shanghai City. These samples were studied by Mössbauer spectroscopy. The experimental results show that ultrafine particles alpha-Fe2O3 (about 13 nm) are the main component of the iron-containing atmospheric aerosols in the tunnel, and high-spin Fe3+ in sulfate containing a small amount of alpha-FeOOH is the main component of iron-containing particles in the aerosols from the other two places. The concentrations of iron in these locations, compared with those of some foreign cities, are much higher. To explore the chemical compositions of iron compounds in aerosols, SPM (scanning proton microprobe) has also been used. From these results, a possible chemical process by which the iron oxides converted to iron sulfate in air was discussed.

Aerosols↗
PubMed1995

The role of iron in beta amyloid toxicity.

There is evidence that oxidative damage plays a causative role in Alzheimer's disease and amyloid beta protein (A beta) toxicity. Iron is frequently a potent facilitator of free radical production due to its ability to mediate the conversion of H2O2 to hydroxyl radicals via the Fenton reaction or by virtue of hypervalent iron compounds. It is shown here that iron facilitates A beta toxicity to cultured cells.

Alzheimer Disease↗
PubMed2002

Iron fortification of foods: overcoming technical and practical barriers.

Iron fortification of food is a methodology utilized worldwide to address iron deficiency. A critical problem in some food fortification programs is the lack of bioavailability of iron compounds. This article reviews presentations on iron fortification programs in the Americas and the technical and practical barriers faced by the programs. Effective programmatic strategies will incorporate systematic consideration of sound program management, ensure consumption of fortified foods, and promote advocacy and supportive legislation. However, these factors are often overlooked or are not addressed coherently. Key components to consider in implementation of iron fortification programs include: utilization of foods and condiments containing fortificants that are bioavailable; program development and its implementation coordinated with targeted communications; utilizing resources from public/private sector partnerships; and operational research on how to overcome practical barriers for successful implementation of fortification.

Anemia, Iron-Deficiency↗
PubMed2004

The mechanisms for regulating absorption of Fe bis-glycine chelate and Fe-ascorbate in caco-2 cells are similar.

Inorganic iron (Fe) absorption from the diet is controlled mainly in the intestinal tract where apical Fe uptake is inversely related to the Fe content in the enterocyte. Iron bis-glycine chelate is an iron compound that may be absorbed by a mechanism different from the regulated nonheme Fe pathway. Because Fe bis-glycine chelate is used increasingly as an Fe fortificant in foods, the critical question is whether this compound is a safe Fe supplement. We compared apical Fe uptake and transepithelial transport offered either as (59)Fe bis-glycine chelate or a (59)Fe-ascorbate (Fe-AA) complex in Caco-2 cells, as a model of human intestinal epithelia, grown in different Fe concentrations in the media (0.5, 5 and 20 micro mol/L Fe). Apical Fe uptake from (59)Fe-AA and (59)Fe bis-glycine chelate did not differ nor did transepithelial transport rates. The rate of (59)Fe uptake decreased with increasing intracellular Fe concentration (P < 0.001), an indication of a common absorption regulatory mechanism. We also evaluated the effect of an excess of Fe (100 micro mol/L) provided as Fe bis-glycine chelate or Fe-AA on the incorporation of 1 micro mol/L (55)Fe-AA into Fe-replete Caco-2 cells. The inhibition of Fe bis-glycine chelate on the absorption of the extrinsic tag of (55)Fe-AA (87.5%) did not differ from that of Fe added as Fe-AA (86.8%). These results suggest that Fe derived from Fe bis-glycine chelate and Fe-AA have similar regulatory absorption mechanisms.

Absorption↗
PubMed1972

Iron-binding proteins in milk and resistance to Escherichia coli infection in infants.

Human milk contains large quantities of iron-binding protein, of which the greater proportion is lactoferrin, though small amounts of transferrin are also present. Three samples of human milk with unsaturated iron-binding capacities of between 56 and 89% had a powerful bacteriostatic effect on Escherichia coli O111/B4. The bacteriostatic properties of milk were abolished if the iron-binding proteins were saturated with iron. Purified human lactoferrin, in combination with specific E. coli antibody, strongly inhibited the growth of E. coli, and this effect was also abolished by saturating the lactoferrin with iron.Guinea-pig milk also contains lactoferrin and transferrin. Newly born guinea-pigs fed on an artificial diet and dosed with E. coli O111 had higher counts of E. coli O111 in the intestine than suckled animals. The apparent suppressive effect of guinea-pig milk on E. coli in the intestine could be reversed by feeding the iron compound haematin. It seems that iron-binding proteins in milk may play an important part in resistance to infantile enteritis caused by E. coli.

Animals↗
PubMed2003

Ultrastructural analysis of a putative magnetoreceptor in the beak of homing pigeons.

With the use of different light and electron microscopic methods, we investigated the subcellular organization of afferent trigeminal terminals in the upper beak of the homing pigeon, Columba livia, which are about 5 microm in diameter and contain superparamagnetic magnetite (SPM) crystals. The SPM nanocrystals are assembled in clusters (diameter, approximately 1-2 microm). About 10 to 15 of these clusters occur inside one nerve terminal, arranged along the cell membrane. Each SPM cluster is embedded in a solid fibrous cup, open towards the cell surface, to which the cluster adheres by delicate fiber strands. In addition to the SPM clusters, a second inorganic iron compound has been identified: noncrystalline platelets of iron phosphate (about 500 nm wide and long and maximally 100 nm thick) that occur along a fibrous core of the terminal. The anatomic features suggested that these nerve endings could detect small intensity changes of the geomagnetic field. Such stimuli can induce deformations of the SPM clusters, which could be transduced into primary receptor potentials by mechanosensitive membrane receptor channels. The subepidermal fat cells surrounding the nerve endings prevent the inside from external mechanical stimuli. These structural findings corresponded to conclusions inferred from rock magnetic measurements, theoretical calculations, model experiments, and behavioral data, which also matched previous electrophysiologic recordings from migratory birds.

Animals↗
PubMed2000

Involvement of iron (ferric) reduction in the iron absorption mechanism of a trivalent iron-protein complex (iron protein succinylate).

Iron protein succinylate is a non-toxic therapeutic iron compound. We set out to characterise the structure of this compound and investigate the importance of digestion and intestinal reduction in determining absorption of the compound. The structure of the compound was investigated by variable temperature Mössbauer spectroscopy, molecular size determinations and kinetics of iron release by chelators. Intestinal uptake was determined with radioactive compound force fed to mice. Reduction of the compound was determined by in vitro incubation with intestinal fragments. The compound was found to contain only ferric iron, present as small particles including sizes below 10 nm. The iron was released rapidly to chelators. Digestion with trypsin reduced the molecular size of the compound. Intestinal absorption of the compound was inhibited by a ferrous chelator (ferrozine), indicating that reduction to ferrous iron may be important for absorption. The native compound was a poor substrate for duodenal reduction activity, but digestion with pepsin, followed by pancreatin, released soluble iron complexes with an increased reduction rate. We conclude that iron protein succinylate is absorbed by a mechanism involving digestion to release soluble, available ferric species which may be reduced at the mucosal surface to provide ferrous iron for membrane transport into enterocytes.

Animals↗
PubMed1994

Differences and similarities in permissive A/J versus non-permissive BALB/c murine macrophages infected with Legionella pneumophila: the role of iron.

Legionella pneumophila, a facultative intracellular pathogen, replicates within and kills thioglycolate-elicited (TG) macrophages from A/J mice, while growth is inhibited in TG macrophages from BALB/c mice which show no impaired viability. The role of iron in BALB/c and A/J macrophages regarding their permissiveness to L. pneumophila intracellular growth was investigated. We previously reported that TG macrophages from the A/J mouse strain readily supported the intracellular growth of L. pneumophila, while resident macrophages from the same strain of mice were not permissive. Recently we also found that such a difference in permissiveness between both A/J macrophage populations may be explained, at least in part, to intracellular availability of iron. In this report, differences in permissiveness to L. pneumophila growth between A/J TG macrophages and BALB/c TG macrophages was not due to intracellular iron availability. BALB/c and A/J TG macrophages exhibited similar expression of transferrin receptor and cellular iron content. The treatment of BALB/c TG macrophages with different iron compounds, namely ferric nitrilotriacetate (12.5-100 microM), ferric citrate (12.5-100 microM) and transferrin (0.5-5 mg ml-1), did not stimulate the intracellular proliferation of L. pneumophila. The reduction of intracellular iron availability by treatment with antibodies against transferrin receptor or with desferrioxamine suppressed the growth of L. pneumophila within BALB/c TG macrophages, suggesting that these cells do not restrict L. pneumophila growth because of iron. The production of nitric oxide was also similar in both macrophage populations, as measured by the Griess reaction. However, the synthesis of oxygen reactive species was three times higher in non-permissive BALB/c macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Microbial iron transport.

Iron, an essential nutrient, is not readily available in aquatic or terrestrial environments or in animal hosts. Therefore, microbes have developed various strategies for acquiring iron while at the same time protecting themselves from iron's potential toxic effects. The major strategies used by bacteria and fungi to acquire iron include production and utilization of siderophores (ferric specific chelators); utilization of host iron compounds such as heme, transferrin, and lactoferrin; and reduction of Fe(III) to Fe(II) with subsequent transport of Fe(II). Selected examples are discussed with attention to which strategies work best in which environments. The similarities and differences among the different systems with respect to iron binding compounds, receptors, and regulation are also presented.

Animals↗
PubMed2004

Particle size reduction and encapsulation affect the bioavailability of ferric pyrophosphate in rats.

Particle size is an important determinant of Fe absorption from poorly soluble Fe compounds in foods. Decreasing the particle size of elemental iron powders increases their absorption. The effect of a reduction in particle size on the bioavailability of ferric pyrophosphate (FePP) is unclear. Encapsulation of iron compounds for food fortification may protect against adverse sensory changes, but at the same time may reduce bioavailability. The hemoglobin (Hb) repletion method in weanling Sprague-Dawley rats (n = 100) was used to compare the relative bioavailability (RBV) of 4 forms of FePP: 1) regular FePP [mean particle size (MPS) approximately 21 microm]; 2) MPS approximately 2.5 microm; 3) MPS approximately 2.5 microm encapsulated in hydrogenated palm oil; and 4) MPS approximately 0.5 microm with emulsifiers. The RBV compared with ferrous sulfate was calculated by the slope-ratio technique. The RBV was 43% for encapsulated MPS approximately 2.5 microm, significantly lower than the other FePP compounds (P < 0.05), 59% for the regular FePP, and 69% for MPS approximately 2.5 microm, not different from each other but significantly lower than ferrous sulfate (P < 0.05), and 95% for emulsified MPS approximately 0.5 microm, comparable to ferrous sulfate. Encapsulation of FePP with hydrogenated palm oil at a capsule:substrate ratio of 60:40 decreased RBV. Particle size reduction increases the RBV of FePP and may make this compound more useful for food fortification.

Animals↗
PubMed2006

Iron enriched yeast biomass--a promising mineral feed supplement.

Yeast biomass enriched with iron could represent a new and safer solution for prevention from anaemia development. Such an iron source is less toxic and has better absorbability in organisms. The purpose of our research was the determination of the most suitable iron source in the cultivation medium for the yeast Saccharomyces cerevisiae, regarding good growth and iron accumulation in cells. Iron(III) citrate, iron(III) chloride, iron(III) nitrate and Fe-EDTA complex were used. The uptake of the chosen iron compound, Fe(III) citrate, by the yeasts Candida intermedia and Kluyveromyces marxianus was also investigated. Different growth behaviour of the three yeast strains in the presence of Fe(III) citrate was observed. The highest amounts of accumulated iron in S. cerevisiae, C. intermedia and K. marxianus biomass were about 13, 20 and 34mgFeg(-1)dry wt., respectively. To optimise the accumulation of iron in K. marxianus and to characterise iron enriched yeast biomass, further experiments are needed.

Animal Feed↗
PubMed1997

Liver MRI with contrast enhancement.

Liver MR imaging has improved substantially in the last decade due to advances in equipment design and pharmaceutical development. Contrast agents for the liver have been examined within three major classes. Extracellular agents (Gd HP-DO3A, Gd DTPA, and Gd DTPA-BMA) are currently in widespread clinical use. Gadolinium chelates with hepatobiliary excretion are in clinical trials (Gd BOPTA and Gd EOB-DTPA). With respect to particulate agents, one (AMI-25) has received Food and Drug Administration (FDA) approval recently. Imaging technique is critical to proper use, with different strategies employed depending on the class of agent. With gadolinium chelates, T1-weighted images are used for visualization, with dynamic scans being important for extracellular agents, and both dynamic and delayed scans being important for agents with hepatobiliary excretion. With the particulate iron compounds, T2-weighted images are used for visualization, with emphasis on delayed imaging.

Clinical Trials as Topic↗
PubMed2001

Strain-specific iron-dependent virulence in Escherichia coli.

For reasons unknown, certain Escherichia coli strains become highly virulent when injected with hemoglobin or other soluble iron sources. Two clinical isolates (virulent and nonvirulent) showed equivalent hemoglobin-mediated growth acceleration in vitro. However, when injected intraperitoneally into mice without hemoglobin, the virulent strain was cleared more slowly (t(1/2), >4 h vs. <30 min). The virulent E. coli strain had a polysialic acid-containing capsule, whereas the nonvirulent strain did not. Virulent E. coli grown at 20 degrees C (which blocks polysialylation) were cleared as rapidly as nonvirulent organisms. In another virulent E. coli strain having abundant outer membrane polysialic acid, targeted deletion of the polysialyltransferase accelerated host clearance and blocked iron-dependent virulence. The iron-dependent virulence of certain E. coli strains may represent the combined effect of slow in vivo clearance-associated, in this case, with outer membrane polysialylation coupled with accelerated growth permitted by iron compounds.

Alcian Blue↗
PubMed1975

Pathways of clearance in mouse lungs exposed to iron oxide aerosols.

The history of particle clearance was studied in lungs of mice serially sacrificed at intervals up to 14 months following single exposures to an aerosol of submicronic, particulate, iron oxide used as a similitude for atmospheric dust. Clearance was followed by light microscopy in unstained and Prussian blue stained frozen and plastic embedded sections, as well as by electron microscopy, where iron oxide can be recognized by its form. Related problems were investigated through histochemical demonstration of acid phosphatase activity in pulmonary lysosomes and Prussian blue staining of various tissues after administration of iron compounds by gastrointestinal and vascular routes. The iron particles settle extensively but not uniformly on pulmonary alveolar surfaces. Clearance is centripetal and involves two mechanisms, an extracellular mechanism fed by fluid currents sweeping across the surfcace, and cellular mechanism principally involving alveolar macrophages. In the early post exposure period both actively remove deposited particles predominantly through the pulmonary airways. By 24 hours uncleared residues have become ingested and clearance thereafter results mainly from cellular action. Macrophages enter bronchial passages where they sometimes continue to pursue normal activities. A chronic phase of clearance begins when deposited particles become sequestered in macrophages of pulmonary connective tissues. These cells are reached by several routes, not least by crossing the bronchial epithelium. Particle clearance from these macrophages is very slow, and residue-containg cells eventually congregate in lymphoid tissues surrounding major bronchi. These findings are discussed as they help to develop an overall picture of clearance from the lungs and as they bear on related topics, such as functional roles of alveolar and pulmonary connective tissue macrophages and the pathogenesis of chronic bronchial disease.

Acid Phosphatase↗
PubMed1991

Effect of iron succinyl-protein complexes on gastrointestinal motility in the fasting dog.

Studying the gastrointestinal motor effects of iron compounds may help to elucidate the mechanism originating the gastrointestinal side effects of frequently reported during martial therapy. The aims of the present study were: (1) to examine the gastrointestinal motor effects of ferrous sulfate (reference compound) and (2) to compare its effects with those of two iron succinyl-protein complexes (ITF 1096 and ITF 282, an iron-albumin and iron-casein complex, respectively). In 6 fasting, conscious dogs, fitted with 8 bipolar electrodes and 3 strain-gauge force transducers along the gastrointestinal tract, gastrointestinal motor activity was recorded. Ferrous sulfate and iron succinyl-protein complexes were administered by an orogastric tube at two dose levels: the lower and higher dose levels were approximately equivalent to 10 and 30 mg/kg as Fe, respectively. In control experiments, 154 mM NaCl, ITF 211 (succinylated albumin) and ITF 297 (succinylated casein) were used. Administration of 154 mM NaCl did not affect gastrointestinal motility nor did it disrupt migrating motor complex (MMC) cycling. ITF 1096 and ITF 282, only at the higher dose, lengthened the MMC period and increased intestinal, but not gastric spike activity. The effects of ITF 211 and ITF 297 were similar to those of ITF 1096 and ITF 282. Ferrous sulfate, at the lower dose, lengthened the MMC period; the higher dose disrupted MMC cycling and induced intense, irregular spike bursts in the stomach and in the small bowel, accompanied, in 3 out of 6 dogs, by a prolonged tonic contraction of the upper small bowel. Four out of 6 dogs vomited after the higher dose of ferrous sulfate. No vomiting was observed with any of the other treatments. We conclude that ITF 1096 and ITF 282 have a markedly better gastrointestinal tolerability than ferrous sulfate.

Animals↗