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PubMed1984

On the therapeutic effects of trivalent and divalent iron in iron deficiency anaemia.

The effectiveness of orally administered iron was investigated using three different iron preparations in a randomized study with 3 patient groups, each consisting of 20 subjects with iron deficiency anaemia. Group A received a ferric(III)-dextrin complex, group B Fe(II)-sulfate, and group C Fe(II)-fumarate with vitamins. For all three preparations the increase in the number of erythrocytes as well as hemoglobin and hematocrit values ran absolutely parallel for a period of 12 weeks. A relevant difference between the trivalent ferric-dextrin complex and the two bivalent iron preparations could not be detected on evaluation of the parameters measured except for a moderate increase in the transaminase values in the patients group who received the Fe(II)-sulfate preparation. No differences were found among the preparations with respect to tolerance. The results are discussed with respect to a possible overloading of the iron transport system by highly absorptive Fe(II)-preparations.

Adult↗
PubMedDate not supplied

[Study of DNA-iron complexes by gamma-resonance spectroscopy].

The re-establishing effect of L-ascorbic acid on DNA-Fe3+ complex was studied with the help of Mössbauer spectroscopy. The ratios (formula: see text) were determined under various conditions of re-establishment. The catalyzing effect of Fe3+ free ions at L-ascorbic acid oxidation by oxygen dissolved in liquid and oxidation of iron in DNA-Fe2+ complex at heating and long keeping was observed.

Ascorbic Acid↗
PubMed1980

Application of content uniformity test to tablet preparations.

Authors have carried out investigations in regard to the application of the Content Uniformity Test (CUT) specified by U. S. P. XIX. On the basis of results obtained with three tablet preparations, they have found that CUT specification may favourably be used, applying appropriate methods of determination, in the case of dosage forms for the better fulfilment of quality requirements. Prescription of the same as requirement postulates the development of supply of quality control both in regard to material and personnel.

Ascorbic Acid↗
PubMed1983

The significance of transferrin for intestinal iron absorption.

A mechanism is proposed by which apotransferrin is secreted from mucosal cells, loaded with iron in the intestinal lumen, and then the intact complex is taken into the cell. Within the cell, iron is released and transferred to the blood stream, whereas iron-free transferrin returns to the brush border to be recycled. We have investigated this hypothesis by measuring intestinal absorption of radioiron and 125I-labeled plasma transferrin using tied-off gut segments in normal and iron-deficient rats. There was no absorption of diferric transferrin from the ileum, but high absorption from the duodenum and jejunum segments. Jejunal absorption occurred as a function of the dose offered and showed saturation kinetics. In normal animals, 4 micrograms of the 50 micrograms of transferrin iron was absorbed over 1 hr. In iron-deficient animals, mean values as high as 13 micrograms were observed. Radioiron content of the jejunal mucosa bore a linear relationship to the dose administered and was inversely proportional to the amount of iron entering the plasma. Recycling of transferrin was indicated by the presence of labeled apotransferrin in the lumen, first observed between 15 and 60 min after the injection of diferric transferrin. A high resistance of diferric and apotransferrin to proteolytic degradation within the gut lumen was demonstrated. Comparative studies with lactoferrin and ferritin disclosed poor availability of their iron for absorption. The small amount that was absorbed did not relate to the iron status of the recipient animal. These studies support the role of mucosal transferrin as a shuttle protein for iron absorption.

Anemia, Hypochromic↗
PubMed1982

The probable binding between cations and stimulatory protein kinase modulator and subsequent stimulation on cerebellar modulator-dependent protein kinases.

The formation of complexes between cations and stimulatory protein kinase modulator (PKMs) were performed by preincubation and gel filtration. The stimulatory effects of Fe3+, Fe2+, Mg2+, and Co2+ complexes on cerebellar modulator-dependent protein kinases (M-PK) were similar to those without preformation of complexes by preincubation and gel filtration. Antagonism by Ca2+ on the stimulatory effect of Mg2+ was noted in spite of the ineffectiveness of Ca2+ when present alone.

Animals↗
PubMed1995

On the "oxygen in heavy-ion tracks" hypothesis.

Two well-known chemical systems, the Fricke (system I) and the Fricke + ethanol (system II), were irradiated with intermediate-energy 12C and 40Ca ion beams. A vertical beam allowed us to study radiation phenomena in the bulk of a stirred solution and in the motionless surface layer in contact with air. The G value of the formation of Fe3+ in system II compared to system I allowed us to distinguish between oxygenated and hypoxic conditions in the reaction zone, i.e., in our case, in the vicinity of the heavy-ion path. Our results for nonstirred solutions that are open to air indicate an oxygen deficiency in the reaction zones even for medium-intensity ion fluences. The origin of this effect is not completely clear at present. Nevertheless, it is evident that postulated mechanisms for the generation of O2 in heavy-ion tracks are not sufficient to keep an oxygenated condition in nonstirred solutions. We cannot exclude the possibility that the low oxygen enhancement ratio observed in experiments with high-LET radiation may arise, at least partly, from an insufficiency rather than an excess of oxygen.

Ferric Compounds↗
PubMed1993

Evaluation of activity of putative superoxide dismutase mimics. Direct analysis by stopped-flow kinetics.

By stopped-flow kinetic analysis, we have directly evaluated the superoxide dismutase (SOD) activity of a number of organic nitroxides and iron- and manganese-based complexes that have been attributed with having SOD activity based upon competition experiments with cytochrome c. In 60 mM HEPES buffer, pH 8.1, or 50 mM potassium phosphate buffer, pH 7.8, Mn(II) and manganese complexes of desferal had no detectable SOD activity by stopped-flow analysis (catalytic rate constant (kcat) < 10(5.5) M-1 s-1), whereas Mn(II) and manganese complexes of desferal inhibited the reduction of cytochrome c by superoxide generated by the xanthine/xanthine oxidase system. Fe(II)-N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (FeTPEN) was eight times more active than Fe(III)-tris[N-(2-pyridylmethyl)-2-aminoethyl]amine(Fe-TPAA) in the cytochrome c assay, but only FeTPAA catalyzed the first-order decay of superoxide (kcat = 2.15 x 10(6) M-1 s-1) by stopped-flow. Fe(III)-tetrakis(4-N-methylpyridyl)porphine (FeTMPP) was active at low micromolar concentrations in both the cytochrome c and stopped-flow assays. At high micromolar concentrations, the organic nitroxides 2,2,6,6-tetramethylpiperidin-1-yloxy (TEMPO) and 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-yloxy (TEMPOL) were inhibitory in the cytochrome c assay, but showed no detectable SOD activity by stopped-flow. None of the tested compounds inhibited xanthine oxidase activity as shown by the measurement of urate production. Under the conditions of the cytochrome c assay, FeTPEN, TEMPO, and TEMPOL oxidized reduced cytochrome c which rationalizes the false positives for these compounds in this assay. The inhibitory activities of Mn(II) and the manganese desferal complexes in the cytochrome c assay appear to be due to a stoichiometric, not catalytic, reaction with superoxide as catalytic amounts of these agents do not induce a first-order decay of superoxide as shown by stopped-flow.

Cyclic N-Oxides↗
PubMed1996

Role of Cu/Zn-superoxide dismutase in xenobiotic activation. I. Chemical reactions involved in the Cu/Zn-superoxide dismutase-accelerated oxidation of the benzene metabolite 1,4-hydroquinone.

Cu/Zn-superoxide dismutase (Cu/Zn-SOD) has been shown to modulate the autoxidation of a variety of phenoic compounds, including 1,4-hydroquinone (HQ), a benzene-derived metabolite. The acceleration of autoxidation of HQ by Cu/Zn-SOD results in the production of 1,4-benzoquinone (BQ). It has been proposed that the chemical mechanism involved in the Cu/Zn-SOD-catalyzed autoxidation of HQ may be occur through either its conventional activity as a superoxide:superoxide oxidoreductase or as a semiquinone:superoxide oxidoreductase. However, Cu/Zn-SOD-accelerated oxidation of HQ has not been resolved experimentally. In this study, with ESR spectroscopy we investigated further the chemical reactions involved in the SOD-accelerated oxidation of HQ. In phosphate-buffered saline (PSB), HQ underwent a slow autoxidation to BQ, which was accelerated by Cu/Zn-SOD, Mn-SOD, or Fe-SOD with similar efficiency. In contrast, among free metals, only Cu(II) strongly mediated the oxidation of HQ to BQ. Mn(II) exhibited a slight capacity to oxidize HQ, whereas neither FE(II) nor FE(III) was capable of modulating the autoxidation of HG. The presence of either form of SOD also dramatically enhanced the formation of semiquinone anion radicals SQ-. from HQ. The SOD-accelerated oxidation of HQ was also accompanied by the generation of H202. In PBS containing bovine serum albumin (BSA) (PBS/BSA), HQ did not undergo autoxidation to SQ-., and as such the presence of SOD was unable to induce the formation of either SQ-. or BQ or the consumption of O2. The addition of 10 microM BQ to HQ (100 or 1000 microM) in PBS/BSA resulted in the formation of SQ-. and initiated a slow rate of oxidation of HQ to BQ. In this case, the presence of Cu/Zn-SOD strongly accelerated the oxidation of HQ to SQ-. and BQ and the utilization of O2. Furthermore, the enhancement by Cu/Zn-SOD of the generation of SQ-. or BQ from HQ in PBS/BSA was extensively inhibited under anaerobic conditions. The enhancement of SQ-. generation from HQ by all three forms of SOD does not support the possibility that Cu/Zn-SOD can oxidize SQ-. to BQ. Taken together, this study demonstrates that unlike free copper, Cu/Zn-SOD does not directly interact with HQ to cause its oxidation to BQ. Rather, the autoxidation of HQ to SQ-. is a prerequisite for the enhancing capacity of Cu/Zn-SOD, and the dismutation of superoxide anion radicals generated from the SQ-. in the presence of O2 appears to be the underlying mechanism responsible for the enhancement by Cu/Zn-SOD of the oxidation of HQ.

Anaerobiosis↗
PubMed1976

Approaches to the standardization of serum unsaturated iron-binding capacity.

An important aspect in the development and use of serum unsaturated iron-binding capacity (UIBC) procedures is the standardization of reference serum. Spectrophotometric titration of serum transferrin is the oldest of the UIBC methods; however, the literature on this subject indicates that the technique is not being fully exploited and describes a variety of suboptimal conditions. A spectrophotometric titration protocol is described which gives excellent reproducibility with fresh, frozen, lyophilized, and stored serum samples. An indirect UIBC method utilizing differential chelation and ultrafiltration is also described. In this method Fe3+ -NTA (nitrilotriacetic acid), in excess of the anticipated UIBC, is added to a serum sample supplemented with NaHC03. The addition of EDTA (ethelenediaminetetraacetic acid) allows the mobilization of iron from nonspecific macromolecular sites. The ultrafiltrate is analyzed for iron, and the UIBC is calculated. The results were validated via an ultrafiltration titration which was compared with a spectrophotometric titration. The precision of this method is excellent.

Anemia, Hypochromic↗