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PubMed1993

Reversal of developmental delays in iron-deficient anaemic infants treated with iron.

Iron-deficient anaemic infants perform worse in tests of mental and motor development than do iron-sufficient infants of a comparable age. A randomised, double-blind trial was done to monitor the effects of iron supplementation on performance in the Bayley scales of mental and motor development among 12-18-month-old infants in Indonesia. Iron-deficient anaemic infants (n = 50) were assigned randomly to receive dietary ferrous sulphate or placebo for 4 month. Similar treatment randomisation was done among nonanaemic iron-deficient (n = 29) and iron-sufficient (n = 47) infants. Before intervention, the mean mental and motor scores of the iron-deficient anaemic infants were significantly (p < 0.01) lower than those of the nonanaemic iron-deficient and iron-sufficient classes. After intervention, developmental delays were reversed among iron-deficient anaemic infants who had received iron but they remained the same among placebo-treated iron-deficient anaemic infants. Neither ferrous sulphate nor placebo had significant effects on the scores of the other two iron-status classes. The poor performance of 12-18-month-old iron-deficient anaemic infants in the Bayley scales of mental and motor development can be improved to the level of performance of iron-sufficient infants by treatment with ferrous sulphate.

Administration, Oral↗
PubMed1990

What the intermediate compounds in ligand binding to hemoglobin tell about the mechanism of cooperativity.

The populations of the intermediates in concentrated solutions of hemoglobin A0 equilibrated at various PCO values, pH 7.0, 0.1 M KCl, and 20 degrees C, have been determined using cryogenic methods. Data on CO saturations and distributions of intermediates were analysed in terms of the free energies of dimer-tetramer assembly of the intermediates (G.K. Ackers and F.R. Smith, Annu. Rev. Biophys. Chem. 16 (1987) 583). The cooperative free energy value of the singly ligated species was approximately one-half the total cooperative energy. The cooperative free energy value of the doubly ligated species was not significantly different from that of carboxyhemoglobin. Because of experimental error, the observed difference in concentrations among the populations of the doubly ligated species cannot be taken as indicative of their functional heterogeneity. Additional studies on some NO intermediates have emphasized that (alpha 1 beta 1)(alpha 2 beta 2)X, a key intermediate in the formulation of the 'third-state' hypothesis in the deoxy/cyanomethemoglobin system, has a free energy value for dimer-tetramer assembly which is critically dependent on the nature of the ligand X as suggested by Ackers and Smith (reference as cited above).

Carboxyhemoglobin↗
PubMed2003

Red blood cell magnetophoresis.

The existence of unpaired electrons in the four heme groups of deoxy and methemoglobin (metHb) gives these species paramagnetic properties as contrasted to the diamagnetic character of oxyhemoglobin. Based on the measured magnetic moments of hemoglobin and its compounds, and on the relatively high hemoglobin concentration of human erythrocytes, we hypothesized that differential migration of these cells was possible if exposed to a high magnetic field. With the development of a new technology, cell tracking velocimetry, we were able to measure the migration velocity of deoxygenated and metHb-containing erythrocytes, exposed to a mean magnetic field of 1.40 T and a mean gradient of 0.131 T/mm, in a process we call cell magnetophoresis. Our results show a similar magnetophoretic mobility of 3.86 x 10(-6) mm(3) s/kg for erythrocytes with 100% deoxygenated hemoglobin and 3.66 x 10(-6) mm(3) s/kg for erythrocytes containing 100% metHb. Oxygenated erythrocytes had a magnetophoretic mobility of from -0.2 x 10(-6) mm(3) s/kg to +0.30 x 10(-6) mm(3) s/kg, indicating a significant diamagnetic component relative to the suspension medium, in agreement with previous studies on the hemoglobin magnetic susceptibility. Magnetophoresis may open up an approach to characterize and separate cells for biochemical analysis based on intrinsic and extrinsic magnetic properties of biological macromolecules.

Cell Movement↗
PubMed1997

Propylene oxide: mutagenesis, carcinogenesis and molecular dose.

The results from mutagenic and carcinogenic studies of propylene oxide (PO) and the current efforts to develop molecular dosimetry methods for PO-DNA adducts are reviewed. PO has been shown to be active in several bacterial and mammalian mutagenicity tests and induces site of contact tumors in rodents after long-term administration. Quantitation of N7-(2-hydroxypropyl)guanine (7-HPG) in nasal and hepatic tissues of male F344 rats exposed to 500 ppm PO (6 h/day; 5 days/week for 4 weeks) by inhalation was performed to evaluate the potential of high concentrations of PO to produce adducts in the DNA of rodent tissues and to obtain information necessary for the design of molecular dosimetry studies. The persistence of 7-HPG in nasal and hepatic tissues was studied in rats killed three days after cessation of a 4-week exposure period. DNA samples from exposed and untreated animals were analyzed for 7-HPG by two different methods. The first method consisted of separation of the adduct from DNA by neutral thermal hydrolysis, followed by electrophoretic derivatization of the adduct and gas chromatography-high resolution mass spectrometry (GC-HRMS) analysis. The second method utilized 32P-postlabeling to quantitate the amount of this adduct in rat tissues. Adducts present in tissues from rats killed immediately after cessation of exposure were 835.4 +/- 80.1 (respiratory), 396.8 +/- 53.1 (olfactory) and 34.6 +/- 3.0 (liver) pmol adduct/mumol guanine using GC-HRMS. Lower values, 592.7 +/- 53.3, 296.5 +/- 32.6 and 23.2 +/- 0.6 pmol adduct/mumol guanine were found in respiratory, olfactory and hepatic tissues of rats killed after three days of recovery. Analysis of the tissues by 32P-postlabeling yielded the following values: 445.7 +/- 8.0 (respiratory), 301.6 +/- 49.2 (olfactory) and 20.6 +/- 1.8 (liver) pmol adduct/mumol guanine in DNA of rats killed immediately after exposure cessation and 327.1 +/- 21.7 (respiratory), 185.3 +/- 29.2 (olfactory) and 15.7 +/- 0.9 (liver) pmol adduct/mumol guanine after recovery. Current methods of quantitation did not provide evidence for the endogenous formation of this adduct in control animals. These studies demonstrated that the target tissue for carcinogenesis has much greater alkylation of DNA than liver, a tissue that did not exhibit a carcinogenic response.

Alkylation↗
PubMed1996

Randomised study of cognitive effects of iron supplementation in non-anaemic iron-deficient adolescent girls.

BACKGROUND: Up to 25% of adolescent girls in the USA are iron deficient. This double-blind, placebo-controlled clinical trial assessed the effects of iron supplementation on cognitive function in adolescent girls with non-anaemic iron deficiency. METHODS: 716 girls who enrolled at four Baltimore high schools were screened for non-anaemic iron deficiency (serum ferritin < or = 12 micrograms/L with normal haemoglobin). 98 (13.7%) girls had non-anaemic iron deficiency of whom 81 were enrolled in the trial. Participants were randomly assigned oral ferrous sulphate (650 mg twice daily) or placebo for 8 weeks. The effect of iron treatment was assessed by questionnaires and haematological and cognitive tests, which were done before treatment started and repeated after the intervention. We used four tests of attention and memory to measure cognitive functioning. Intention-to-treat and per-protocol analyses were done. FINDINGS: Of the 81 enrolled girls with non-anaemic iron deficiency, 78 (96%) completed the study (39 in each group). Five girls (three control, two treatment) developed anaemia during the intervention and were excluded from the analyses. Thus, 73 girls were included in the per-protocol analysis. Ethnic distribution, mean age, serum ferritin concentrations, haemoglobin concentrations, and cognitive test scores of the groups did not differ significantly at baseline. Postintervention haematological measures of iron status were significantly improved in the treatment group (serum ferritin 27.3 vs 12.1 micrograms/L, p < 0.001). Regression analysis showed that girls who received iron performed better on a test of verbal learning and memory than girls in the control group (p < 0.02). INTERPRETATION: In this urban population of non-anaemic iron-deficient adolescent girls, iron supplementation improved verbal learning and memory.

Adolescent↗
PubMed1999

Methods for biological monitoring of propylene oxide exposure in Fischer 344 rats.

Propylene oxide (PO) is used as an intermediate in the chemical industry. Human exposure to PO may occur in the work place. Propylene, an important industrial chemical and a component of, for example, car exhausts and cigarette smoke, is another source of PO exposure. Once taken up in the organism, this epoxide alkylates macromolecules, such as haemoglobin and DNA. The aim of the present investigation was to compare two methods for determination of in vivo dose, the steady state concentration of PO in blood of exposed rats and the level of haemoglobin adducts. Male Fischer 344 rats were exposed for 4 weeks (6 h/day, 5 days/week) to PO at a mean atmospheric concentration of 500 ppm (19.9 micromol/l). Immediately after the last exposure blood was collected in order to determine the steady state concentration of PO. Free PO was measured in blood samples of three animals by means of a head space method to be 37 +/- 2 micromol/l blood (mean +/- S.D.). Blood samples were also harvested for the measurement of haemoglobin adducts. N-2-Hydroxypropyl adducts with N-terminal valine in haemoglobin were quantified using the N-alkyl Edman method with globin containing adducts of deuterium-substituted PO as an internal standard and N-D,L-2-hydroxypropyl-Val-Leu-anilide as a reference compound. Tandem mass spectrometry was used for adduct quantification. The adduct levels were < 0.02 and 77.7 +/- 4.7 nmol/g globin (mean +/- S.D.) in control animals (n = 7) and in exposed animals (n = 34), respectively. The adduct levels expected at the end of exposure were calculated to be 71.7 +/- 4.1 nmol/g globin (mean +/- S.D.) using the measured steady state concentration of PO in blood and taking into account the growth of animals, the life span of erythrocytes, the exposure conditions and the second order rate constant for adduct formation. The good agreement between the estimated and measured adduct levels indicates that both end-points investigated are suitable for biological monitoring.

Animals↗
PubMed2001

Bioavailability study of dried microencapsulated ferrous sulfate--SFE 171--by means of the prophylactic-preventive method.

Microencapsulated ferrous sulfate with soy lecithin (SFE-171) has been used as an iron source for the fortification of milk and dairy products. With the purpose to extend the use of this agent to other kind of foods or even to pharmaceutical preparations for oral administration, the SFE-171 was turned into a fluid powder (SFE-171-P) by means of vacuum drying. The iron bioavailability (BioFe) of SFE-171-P was evaluated in this work by means of the prophylactic-preventive method in rats, using ferrous sulfate as reference standard. Both iron sources were separately added to a basal diet of low iron content in a concentration of 10 mg iron/kg diet. Two groups of 10 weaned rats 25 days old received the fortified diets during 28 days, while a third group of the same size received the basal diet without iron additions. The weights and haemoglobin concentrations (HbC) of every animal were determined before and after the treatment, thus allowing the calculation of the mass of iron incorporated into haemoglobin (HbFe) during this period. The BioFe of the iron sources were obtained as the percentage ratio between the HbFe and the mass of iron consumed by each animal. The results were also given as Relative Biological Value (RBV), which relates the BioFe of the studied source with that of the reference standard. The liver iron concentration (LIC) of each animal was determined at the end of the experiment in order to evaLuate the influence of the studied iron sources on the liver iron stores. SFE-171-P presented BioFe, RBV and LIC values of (47 +/- 7)%, 109% and (46.6 +/- 3.4) mg/kg respectively, while the corresponding values for the reference standard were of (43 +/- 7)%, 100% and (45.0 +/- 4.7) mg/kg. These results show that the drying process used to produce the SFE-171-P does not affect its bioavailability, which is also adequate for the potential use of this product in food fortification or with pharmaceutical purposes.

Animals↗
PubMed1976

Influence of globin structures on the state of the heme. Ferrous low spin derivatives.

Studies of high spin ferrous and ferric derivatives led us to conclude that in the quaternary R structure the state of the hemes is similar to that in the free alpha and beta subunits, but in the T structure a tension acts on the hemes which tries to pull the iron and the proximal histidine further from the plane of the porphyrin. We have now studied the effect of inositol hexaphosphate (IHP) on the three low spin ferrous compounds of hemoglobin with O2, CO, and NO. IHP failed to switch the quaternary structure of carbonmonoxy- and oxyhemoglobin A to the T state, but merely caused a transition to an as yet undefined modification of the R structure. IHP is known to cause a switch to the T structure in hemoglobin Kansas. We have found that this switch induces red shifts of the visible alpha and beta absorption bands and the appearance of a shoulder on the red side of the alpha band; these changes are very weak in carbonmonoxy- and slightly stronger in oxyhemoglobin Kansas. As already noted by previous authors, addition of IHP to nitrosylhemoglobin A induces all the changes in uv absorption and CD spectra, sulfhydryl reactivities, and exchangeable proton resonances normally associated with the R leads to T transition, and is accompanied by large changes in the Soret and visible absorption bands. Experiments with nitrosyl hybrids show that these changes in absorption are caused predominantly by the hemes in the alpha subunits. In the accompanying paper Maxwell and Caughey (J. C. Maxwell and W. S. Caughey (1976), Biochemistry, following paper in this issue) report that the NO in nitrosylhemoglobin without IHP gives a single ir stretching frequency characteristic for six-coordinated nitrosyl hemes; addition of IHP causes the appearance of a second ir band, of intensity equal to that of the first, which is characteristic for five-coordinated nitrosyl hemes. Taken together, these results show that the R leads to T transition causes either a rupture or at least a very dramatic stretching of the bond from the iron to the heme-linked histidine, such that an equilibrium is set up between five- and six-coordinated hemes, biased toward five-coordinated hemes in the alpha and six-coordinated ones in the beta subunits. The reason why IHP can switch nitrosyl-, but not carbonmonoxy- or oxyhemoglobin A, from the R to the T structure is to be found in the weakening of the iron-histidine bond by the unpaired NO electron and by the very short Fe-NO bond length.

Binding Sites↗
PubMed2002

Myoglobin-induced lipid oxidation. A review.

An overview of myoglobin-initiated lipid oxidation in simple model systems, muscle, and muscle-based foods is presented. The potential role of myoglobin spin and redox states in initiating lipid oxidation is reviewed. Proposed mechanisms for myoglobin-initiated lipid oxidation in muscle tissue (pH 7.4) and meat (pH 5.5) are evaluated with the purpose of putting forward general mechanisms explaining present observations regarding the catalytic events.

Animals↗
PubMed2005

Tissue iron distribution and adaptation of iron absorption in rats exposed to a high dietary level of NaFeEDTA.

Although it has been shown that iron absorption from NaFeEDTA, a promising iron fortificant, is effectively down-regulated in iron-loaded rats, effects of prolonged exposure to high dietary levels of NaFeEDTA are not well understood. The objectives of this study were to determine whether rats can adapt to a high dietary level of NaFeEDTA by down-regulating iron absorption, and to determine effects on tissue iron distribution, with or without an iron absorption inhibitor. Male Sprague-Dawley rats were exposed to diets supplemented with FeSO4 or NaFeEDTA at 1200 mg of Fe/kg of diet, with or without tea, for 27 days. Iron absorption measured by whole-body counting before and after exposure showed that rats adapted to the high dietary level of FeSO4 or NaFeEDTA by down-regulating iron absorption to a similar extent. However, nonheme iron concentrations in liver and spleen were about 35-50% lower, whereas the concentration in kidney was about 300% higher in rats fed NaFeEDTA, compared to rats fed FeSO4. Tea had no major impact on iron absorption or iron status, regardless of iron source. Our results showed that although iron absorption was down-regulated similarly, body iron distribution was markedly different between rats exposed to FeSO4 and those exposed to NaFeEDTA. Further studies are warranted to determine the effects of prolonged exposure to dietary NaFeEDTA on kidney iron accumulation and kidney function.

Absorption↗
PubMed2002

Complexities in ETS-domain transcription factor function and regulation: lessons from the TCF (ternary complex factor) subfamily. The Colworth Medal Lecture.

The ETS-domain transcription factor family can be divided into a series of subfamilies. Elk-1 represents the founding member of the ternary complex factor (TCF) subfamily. By focusing on the TCF subfamily, we can demonstrate the complexities that exist in the function and regulation of ETS-domain transcription factors. This article focuses on Elk-1 in detail and summarizes the functions of other TCFs. The key themes covered include the domain structure of the TCFs, the mechanisms of complex formation with serum response factor, regulation of TCFs by mitogen-activated protein kinase cascades, and transcriptional regulatory properties of the TCFs. Finally, the emerging role of the TCFs in vivo is discussed. A picture is developing indicating that, while these proteins exhibit significant sequence and functional conservation, key differences in their structure and regulation are being identified which may relate to unique functions of these proteins in vivo.

Amino Acid Sequence↗