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The effect of change in pH on the solubility of iron bis-glycinate chelate and other iron compounds.

The effect of a pH change from 2 to 6 was tested on the solubility of ferrous sulfate, ferrous fumarate, iron bis-glycine chelate (Ferrochel) and sodium-iron ethylenediaminetetraacetic acid (NaFeEDTA). It was found that at pH 2 ferrous sulfate, Ferrochel and NaFeEDTA were completely soluble and only 75% of iron from ferrous fumarate was soluble. When pH was raised to 6, iron from amino acid chelate and NaFeEDTA remained completely soluble while solubility from ferrous sulfate and ferrous fumarate decreased 64 and 74%, respectively compared to the amount of iron initially soluble at pH 2. These results suggest that iron solubility from iron bis-glycine chelate and NaFeEDTA is not affected by pH changes within the ranges tested, probably because iron remained associated to the respective compounds.

Edetic Acid↗

Genotoxicity of iron compounds in Salmonella typhimurium and L5178Y mouse lymphoma cells.

The mutagenic activity of elemental and salt forms of iron (Fe), including compounds currently being used in dietary supplements and for food fortification, were evaluated for mutagenicity in Salmonella typhimurium and L5178Y mouse lymphoma cells. Except for the weak response obtained with ferrous fumarate, none of the compounds induced a mutagenic response in Salmonella. In the mouse lymphoma assay, responses were related to the Fe compound and/or reduction of ferric (Fe+3) to ferrous (Fe+2). Responses with the elemental forms of Fe were divergent. Electrolytic Fe with a relatively larger particle size and irregular shape was negative. The smaller-sized carbonyl Fe, which after 4 hr attached to and was taken up by the cells, induced mutagenic responses both with and without S9. With ferric chloride (FeCl3) and ferric phosphate (FePO4), there was an increase in mutant frequency only with S9. With the Fe+2 compounds, ferrous sulfate (FeSO4) and ferrous fumarate (FeC4H2O4), positive responses were observed without S9. The Fe chelate, sodium Fe(III)EDTA was positive in both the presence and absence of S9. The lowest effective doses (LED) for induction of mutagenicity were identified for these compounds and an LED ratio calculated. The LED ratio ranges from 1 for FeSO4 to 30 for carbonyl Fe, which are similar to oral LD50 values obtained in animal studies.

Animals↗

Virulence of iron transport mutants of Shigella flexneri and utilization of host iron compounds.

Mutants of Shigella flexneri defective in aerobactin-mediated iron transport were assayed for virulence in several model systems. A Tn5 insertion mutant was invasive in HeLa cells, lethal in the chicken embryo, and produced keratoconjunctivitis in the guinea pig, indicating little or no loss of ability to invade and multiply intracellularly. Although the mutant failed to grow in low-iron medium in vitro, growth equivalent to that of the wild type was observed in HeLa cell lysates. Thus, there appears to be sufficient available iron inside the HeLa cell to allow growth in the absence of siderophore synthesis. Possible host iron sources were tested, and both the mutant and wild type utilized hemin or hematin as a sole source of iron. Only the wild-type, aerobactin-producing strain could remove iron from transferrin or lactoferrin. Two deletion mutants were also assayed for virulence and were found to be avirulent for the chicken embryo. These deletions encompass flanking sequences as well as the aerobactin genes; therefore, adjacent genes may be required for virulence.

Animals↗

Iron compounds after erythrophagocytosis: chemical characterization and immunomodulatory effects.

In humans, the lymphomyeloid system has a fundamental role on iron metabolism promoting its recycling due to a continuous removal of effete red blood cells. Additionally, one of the most intriguing aspects of metalloporphyrins in biology is their effect on the immune system. However, the process of erythrocyte catabolism is still poorly understood and needs further research. In the present study, we attempt to investigate the nature and the possible physiologic role of Fe compounds released after erythrophagocytosis during the removal of red blood cells. Monocyte erythrophagocytosis in vitro experiments were done to characterize chemically the Fe compounds present inside the cells and in the culture supernatants. We tested the probable immunomodulatory functions of erythrophagocytosis products over lymphocyte cultures activated in vitro with T mitogens (alpha-CD3). Data obtained from atomic absorption spectroscopy confirmed the presence of Fe in the culture supernatants of monocyte cultures after erythrophagocytosis. Also, high-spin haem complexes derived from erythrocyte catabolism were detected by electron paramagnetic electronic resonance. Finally, in vitro activated lymphocyte proliferation experiments indicate the co-mitogenic properties of monocyte culture supernatants after red blood cells phagocytosis. Thus, the results of the present work provide evidence that culture monocyte supernatants after in vitro erythrophagocytosis contain Fe (III) high-spin haem complexes and show lymphocyte proliferation co-stimulatory properties.

Adjuvants, Immunologic↗

Parenteral iron compounds sensitize mice to injury-initiated TNF-alpha mRNA production and TNF-alpha release.

Intravenous Fe is widely used to treat anemia in renal disease patients. However, concerns of potential Fe toxicity exist. To more fully define its spectrum, this study tested Fe's impact on systemic inflammation following either endotoxemia or the induction of direct tissue damage (glycerol-mediated rhabdomyolysis). The inflammatory response was gauged by tissue TNF-alpha message expression and plasma TNF-alpha levels. CD-1 mice received either intravenous Fe sucrose, -gluconate, or -dextran (FeS, FeG, or FeD, respectively; 2 mg), followed by either endotoxin (LPS) or glycerol injection 0-48 h later. Plasma TNF-alpha was assessed by ELISA 2-3 h after the LPS or glycerol challenge. TNF-alpha mRNA expression (RT-PCR) was measured in the kidney, heart, liver, lung, and spleen with Fe +/- LPS treatment. Finally, the relative impacts of intramuscular vs. intravenous Fe and of glutathione (GSH) on Fe/LPS- induced TNF-alpha generation were assessed. Each Fe preparation significantly enhanced LPS- or muscle injury-mediated TNF-alpha generation. This effect was observed for at least 48 h post-Fe injection, a time at which plasma iron levels were increased by levels insufficient to fully saturate transferrin. Fe did not independently increase plasma TNF-alpha or tissue mRNA. However, it potentiated postinjury-induced TNF-alpha mRNA increments and did so in an organ-specific fashion (kidney, heart, and lung; but not in liver or spleen). Intramuscular administration, but not GSH treatment, negated Fe's ability to synergize LPS-mediated TNF-alpha release. We conclude 1) intravenous Fe can enhance TNF-alpha generation during LPS- or glycerol-induced tissue damage; 2) increased TNF-alpha gene transcription in the kidney, heart, and lung may contribute to this result; and 3) intramuscular administration, but not GSH, might potentially mitigate some of Fe's systemic toxic effects.

Anemia↗

Surface treatment of dentin with GLUMA and iron compounds for bonding indirect restorations.

The purpose of this study was to evaluate five dentin bonding systems simulating indirect restorations. The surface of bovine and human dentin was primed with a glutaraldehyde agent (GLUMA) and placed in a humidor at 37 degrees C for 168 h. In an experimental bonding system (GLUMA/CY/SB), the surfaces were etched with phosphoric acid, primed with cytochrome c, and then bonded to an acrylic rod with a self-curing resin (4-META/MMA-TBB). Specimens using two commercially available bonding systems [All-Bond 2 (AB2) and Super-Bond C & B (10-3/SB)] and two controls with and without GLUMA (GLUMA/10-3/SB and CY/SB) were also prepared. Tensile testing revealed that the bond strengths were influenced by the bonding system, 168 h dentin exposure and their interaction, but not by the tooth origin. AB2 showed the lowest bond strength. With the 10-3/SB system, exposing the dentin to humidity resulted in a decrease in bond strength. After 168 h of exposure, no significant differences were observed between 10-3/SB and CY/SB. The most effective bonding was obtained with the bonding systems of GLUMA/10-3/SB and GLUMA/CY/SB. Improved outcome is expected with these bonding systems when building up abutment teeth with indirect restorations.

Analysis of Variance↗

Identification and characterization of the iron compounds in bone marrow by means of Mössbauer spectrometry.

In order to determine and to demonstrate the cellular iron molecular states in hematopoietic bone marrow, direct investigations were performed by means of different and complementary spectroscopic techniques: optical absorption, electron spin resonance and Mössbauer spectrometry. In fact, the latter appears to have been the most informative. In addition to the hemoglobin forms, five- and six-coordination ligand protoporphyrins IX (monomeric and polymeric stacking, respectively) were observed. A small amount of non-hemic high-spin iron III storage component (ferritin) was measured. No diferric transferrin was detected. A ferrous compound was also observed and attributed to the mitochondrial iron pool.

Bone Marrow↗