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At least 19 recordsLinked to original sources
PubMed1991

Absorption of low and therapeutic doses of ferric maltol, a novel ferric iron compound, in iron deficient subjects using a single dose iron absorption test.

Ferric maltol is a novel ferric iron compound with potential use as an oral therapy for iron deficiency anaemia. Using a single, low dose iron absorption test we compared absorption of ferric maltol with absorption of ferrous sulphate in 21 iron deficient subjects. Absorption of 10 mg of ferric maltol as either aqueous solution or a single tablet compared favourably with that of an equivalent dose of ferrous sulphate. At a higher, more therapeutic dose of 60 mg elemental iron as tablets, absorption of ferric maltol appeared to be both more rapid and total absorption greater, than that seen with ferrous sulphate. We conclude that iron from ferric maltol, both at low dose and higher, more therapeutic doses, is at least as well absorbed as from ferrous sulphate. Ferric maltol is the first ferric iron formulation to be absorbed to a degree equivalent to that of ferrous iron salts and may represent a viable form of administration for ferric iron in the treatment of iron deficiency anaemia.

Adult↗
PubMedDate not supplied

Differential regulation of ferritin expression in Friend leukemia cells by iron compounds.

Ferritin is an ubiquitous iron storage protein that plays a key role in determining the intracellular fate of iron. Therefore, ferritin synthesis is highly regulated by the iron status of the cell through post-transcriptional mechanisms that involve a specific high-affinity interaction between an iron-responsive element (IRE) in the 5' untranslated region of ferritin mRNA and a 98 kDa cytoplasmic protein, the iron-regulatory factor (IRF). The mechanisms that regulate the expression of the iron storage protein ferritin were investigated in erythroid (Friend erythroleukemia cell, FLC) and fibroblastic (L929 and B6) cell lines after exposure to various iron compounds. Both hemin (ferric protoporphyrin IX) and iron (as ferric ammonium citrate, FAC) were used as inducers of ferritin synthesis. Administration of hemin increases ferritin synthesis 8-12 fold both in erythroid and in non-erythroid cell lines, whereas FAC is a weak inducer of ferritin in FLC (only 5-fold). These results correlate with ferritin mRNA expression in FLC observed after hemin treatment compared to the effect exerted by FAC administration. This differential effect suggests that heme is the physiological compound able to stimulate ferritin synthesis in erythroid cell lines and that it plays an important physiological role in regulating gene expression in developing erythroid cells.

Deferoxamine↗
PubMed1978

Intramuscular injections of iron compounds and oncogenesis in man.

To evaluate the evidence for iron compounds as local carcinogens in man, histological material and clinical reports have been reviewed in seven of the eight published cases of tumours developing at the site of intramuscular injections. The microscopical appearances suggested benign lesions in two cases and a variety of tumours in the other five. In only two cases (a rhabdomyosarcoma and a fibrosarcoma) was the interval between injections and tumour development longer than six years. Of the remaining three tumours, one was considered to be a rather slowly growing haemangiopericytoma (with an interval of two years), one appeared to be a subcutaneous lymphoma with no evidence of having arisen in the gluteal muscles, and one was a pleomorphic sarcoma with a possible five-year interval. Sarcomas induced experimentally by iron compounds differ in being less variable in type and in containing abundant iron-containing macrophages, which were negligible in these human tumours.Although the total number of patients who have received intramuscular injections of iron compounds is not known, the present findings, in contrast to experimental work, do not support the view that such treatment carries a strong risk of tumour development.

Adolescent↗
PubMed1981

Ability of Neisseria gonorrhoeae, Neisseria meningitidis, and commensal Neisseria species to obtain iron from transferrin and iron compounds.

The ability of Neisseria species to use iron compounds and to compete with iron-binding proteins was examined with deferrated defined medium and the iron chelator deferoxamine. All Neisseria species were able to assimilate a variety of ferric and ferrous iron salts. They were not able to efficiently solubilize an inorganic iron salt such as ferric nitrate, but were able to use iron chelated by citrate, oxalacetate, pyrophosphate, or nitrilotriacetate. Each of the 95 Neisseria isolates examined was able to use hemin as a sole source of iron, and most, but not all, of the isolates were able to obtain iron from hemoglobin. Heated human serum stimulated growth of all gonococci, meningococci, and some commensal Neisseria species in iron-deficient medium. All gonococci and meningococci were able to scavenge iron from 25% saturated transferrin, whereas most commensal organisms were inhibited by this iron-binding protein. The ability to compete with transferrin was specific, since partially saturated conalbumin was bacteriostatic for all Neisseria species. Although the pathogenic Neisseria species were able to compete more efficiently with transferrin for iron than were the nonpathogenic Neisseria species, no correlation was observed between the virulence of different strains or colony types of gonococci and the ability to scavenge iron in vitro from transferrin or other chelators.

Blood↗
PubMed1981

Polynuclear iron compounds in human transferrin preparations.

During commonly used saturation procedures of transferrin with iron compounds, both as ferri and ferrous, polynuclear iron compounds are easily formed, even when nitrilotriacetate (NTA) is used as a strong iron ligand. The presence of these nonspecific bound irons is demonstrated with Mossbauer spectroscopy and with electronic optical spectroscopy. But no evidence, however, has been found of two different iron binding sites. Because dialysis is not able to remove all polynuclear iron, an easy method with gel filtration has been developed that does remove the polynuclear iron. Some notes are made about the often used method, in transferrin biochemistry, of saturation determination, i.e. the quotient of the absorbances of 470 and 280 nm.

Binding Sites↗
PubMed1998

Iron compounds catalyze the oxidation of 10-formyl-5,6,7,8 tetrahydrofolic acid to 10-formyl-7,8 dihydrofolic acid.

We have previously demonstrated that 10-formyl-7,8-dihydrofolic acid (10-HCO-H2folate) is a better substrate for mammalian aminoimidazolecarboxamide ribotide transformylase (EC 2.1.2.3) than is 10-formyl-5,6,7,8-tetrahydrofolic acid (10-HCO-H4folate) (J.E. Baggott, G.L. Johanning, K.E. Branham, C.W. Prince, S.L. Morgan, I. Eto, W.H. Vaughn, Biochem. J. 308, 1995, 1031-1036). Therefore, the possible metabolism of 10-HCO-H4folate to 10-HCO-H2folate was investigated. A spectrophotometric assay for the oxidation of 10-HCO-H4folate to 10-HCO-H2folate which measures the disappearance of reactant (decrease in absorbance at 356 nm after acidification of aliquots of the reaction solution), is used to demonstrate that iron compounds catalyze the oxidation of 10-HCO-H4folate to 10-HCO-H2folate in the presence and absence of ascorbate. Chromatographic separation of the 10-HCO-H2folate product from the reaction mixture, its UV spectra, a microbiological assay and an enzymatic assay established that the iron-catalyzed oxidation product of 10-HCO-H4folate was 10-HCO-H2folate; without substantial side reactions. The inhibition of this iron-catalyzed oxidation by deferoxamine, apotransferrin and mannitol and the stimulation by citrate and EDTA indicated of a mechanism involving a reaction of 10-HCO-H4folate with hydroxyl radicals (*OH) generated by Fenton chemistry. The presence of "free iron" (e.g., Fe3+ citrate) in bile, cerebrospinal fluid and intracellularly suggest that this oxidation could occur in vivo and that 10-HCO-H4folate may be a *OH scavenger.

Animals↗
PubMed1995

Inhibition of adenylyl cyclase in rat striatal homogenates by combinations of dopamine and ferric iron compounds.

The adenylyl cyclase activity of homogenates of striatal tissue from rat brain has been used as a model to test the hypothesis that the products of the reaction of polyphenols with ferric iron compounds are toxic. Dopamine (DA), at levels that stimulate adenylyl cyclase, inhibited the activity in the presence of 2 mol of potassium ferricyanide (FC), methemoglobin or ferricytochrome c per mol of DA. Combinations of potassium ferrocyanide and DA were not inhibitory. Neither pyrocatechol nor hydroquinone stimulated the activity, but these polyphenols were inhibitory in the presence of FC. Tyramine, phosphorylated DA or phosphorylated pyrocatechol had no effect on the activity of the enzyme in the presence or absence of FC. Forskolin was unable to stimulate the adenylyl cyclase once the latter was inhibited by DA plus FC, and dithiothreitol could not reverse inhibition by DA plus FC. Incubation of DA with FC, in the absence of the homogenate, resulted in substances that were not inhibitory. These findings suggest that the polyphenols plus FC react to yield substances that inhibit the adenylyl cyclase by affecting the catalytic unit of the enzyme complex.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1976

Factors affecting the susceptibility of staphylococci to killing by the cationic proteins from rabbit polymorphonuclear leucocytes: the effects of alteration of cellular energetics and of various iron compounds.

Anaerobiosis, various respiratory inhibitors and certain agents altering cellular energetics profoundly affect the staphylocidal action of the cationic proteins from rabbit polymorphonuclear leucocytes. It is suggested that sensitivity to these proteins depends on the structure of the cell membrane as influenced by (1) the oxidation level of the cytochrome chain and (2) its energized state. Agents such as amytal and rotenone, which cause a block at the beginning of the chain and would increase its oxidation level, enhance killing, whereas those causing a block in or at the end of the chain, such a 2-n-heptyl-4-hydroxyquinoline-N-oxide, cyanide and anaerobiosis, which would cause reduction of a part or whole of the chain, prevent killing. Among agents altering the energized state of the membrane, dicyclohexyl-carbodi-imide, an ATPase inhibitor, does not prevent killing, whereas 2,4-dinitrophenol, carbonylcyanide-trifluoromethoxy-phenylhydrazone and 5-Cl, 3-t-butyl, 2'-Cl, 4'-NO2-salicylanilide, all uncouplers and ionophores for a specific ion, do prevent killing, although gramicidin, a relatively nonspecific ionophore, does not. The paper also contains an extension of previous work on the effect of iron and haematin, to include various other iron compounds and haematin derivatives.

Amobarbital↗
PubMed1988

Accumulation of iron and iron compounds in liver tissue. A comparative study of the histological and chemical estimation of liver iron.

Unsatisfactory results obtained by histological evaluation of liver tissue in iron loading diseases prompted us to study the distribution of the total liver iron, haem iron and ferritin iron in post mortem human liver tissue from two different sites of the same liver. The total liver iron content was measured by flameless atomic absorption spectroscopy in native liver homogenates and in acid digested liver tissue from 60 consecutive autopsies, and the results from the two methods were compared. From the standard deviation of the duplicate analyses, it was deduced that the liver iron is possibly inhomogeneously distributed. The CVduplo (22%) of total iron, measured in acid digested tissue was higher than the CVduplo (14%) of total iron in homogenates from liver tissue from which non-homogenized tissue e.g. vessel walls, fibrotic tissue, had been removed. The CVduplo of ferritin iron and haem iron in liver homogenate was 14% and 30% respectively. The ferritin iron increased with an increasing total iron content until saturation of ferritin iron appeared to be reached at 2.5 micrograms ferritin iron per mg liver protein. When the results of total non-heam liver iron measurements are expressed properly (amount of iron per amount of homogenized liver protein), the distribution of iron is found to be homogeneous in both normal and pathological liver tissues. It was concluded that the estimation of liver iron content by visual microscopic evaluation is unsatisfactory, and that more reliable results are obtained by atomic absorption spectrophotometry.

Ferric Compounds↗
PubMed1976

Observations and interpretation of x-ray absorption edges in iron compounds and proteins.

X-ray absorption spectra near the Kalpha edge have been measured in various iron group compounds using the intense synchrotron radiation at the Stanford Synchrotron Research Project. In the cubic compounds KMF3 where M = Mn+2, Fe+2, Co+2, Ni+2, and Zn+2, well resolved lines were observed and assigned to the 1s leads to 3d, 1s leads to 4s, and 1s leads to 4p transitions. The observed energies agreed rather well with the spectroscopic energy levels of the Z + 1 ion and the intensities are shown to agree with those expected on the basis of one electron transitions of the form Z 1s2dn(L,S) leads to (Z + 1)1s2dnn'l'(L",S). The energies of the intense 1s leads to 4p transition increase by about 5 V going from KFeF3 to K2NaFeF6, but only by about 1 V from K4Fe(CN)6 to K3Fe(CN)6. The transitions confirm that upon oxidation of the hexacyanides the iron electronic structure barely changes. In the iron sulfur protein rubredoxin, where the iron is bound to a tetrahedron of sulfurs, the 1s leads to 3d transition was about seven times more intense than the same transition in an octahedrally coordinated compound. These intensities parallel those observed in the d-d transitions of optical spectra, because in both types of spectra the intensities depend upon 4p admixture. In the heme protein cytochrome c, upon oxidation the 1s leads to 4p transition shifts only about 1 V to higher energies similar to the iron hexacyanides. These results are discussed in terms of covalent bonding.

Cytochrome c Group↗