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PubMed1980

Binding of O2 and CO to hemes and hemoproteins.

Enthalpies and entropies have been determined for the reversible binding of O2 and CO to chelated protoheme, a compound having a covalently attached imidazole bound to the iron. The values, based upon 1 atm standard state, are delta HO2 = -14.0 kcal (1 kcal = 4.18 kJ)/mol, delta SO2 = -35 eu, delta HCO = -17.5 kcal/mol, delta SCO = -34 eu, delta H identical to O2 = 21 kcal/mol (dissociation), and delta H identical to CO = 25 kcal/mol (dissociation). The similarity of these values to those of high-affinity hemoproteins such as isolated hemoglobin chains or R-state hemoglobin (delta HO2 = -13.5, delta HCO = -17.5) show that this model compound accurately mimics the dynamic behavior of these hemoproteins, in contrast to the behavior of other, more elaborate, model compounds. The enthalpy of the replacement of O2 by CO, delta HM, is 3.5 kcal/mol, abut the same as that of R-state hemoglobin. This result obtained with the model compound which most resembles the hemoglobin active site, indicates that distal side steric effects in these hemoproteins neither decrease CO affinity nor differentiate between the binding of CO anmd O2. Consequences of these findings in the binding of O2 and CO to hemoproteins are discussed.

Carbon Monoxide↗
PubMed1987

O-carbamoylsalicylates: agents for modification of hemoglobins.

To combine the attractive features of cyanate and of O-acetylsalicylate as hemoglobin-modifying agents we have prepared carbamoylsalicylate. This compound is a close analogue of aspirin and also resembles a masked cyanate. O-Carbamoylsalicylate and some related carbamates modify hemoglobin substantially, even at 5 mM concentration.

Antisickling Agents↗
PubMed1985

Heme-linked spectral changes of the protein moiety of hemoproteins in the near ultraviolet region.

Spectral changes of hemoproteins in the near ultraviolet region on binding to a ligand and on oxidation-reduction of the heme-iron were studied by computer-controlled spectrophotometry. Near ultraviolet difference spectra between the low spin and high spin forms of ferric hemoproteins were classified into three groups: Those showing two absorption peaks having maxima at around 285 and 295 nm, those showing a peak at around 275 nm, and those showing a peak at around 300 nm. No corresponding absorption peak was observed with model heme complexes of low molecular weight. The intensity of the peak in cyanide difference spectra of catalase and horseradish peroxidase in the near ultraviolet region was dependent on the concentration of added cyanide and paralleled the intensity of the spectral changes in the Soret region. The spectral changes in both the near ultraviolet and Soret regions developed within 6 ms after the addition of cyanide. Difference spectra between the reduced and oxidized forms of cytochrome c, cytochrome oxidase-cyanide complex, hemoglobin, and lactoperoxidase-cyanide complex showed a characteristic peak at around 285-290 nm. Various difference spectra of hemoglobin in the near ultraviolet region were also measured. The observed positions, shapes, combinations, and relative intensities of the peaks were compared with those of solvent perturbation difference spectra and pH difference spectra of proteins and aromatic amino acids and also with the diacetylchitobiose-induced difference spectrum of lysozyme. The kinds of aromatic amino acid residues possibly responsible for the observed difference peaks were discussed on the basis of the results of the comparison. Based on the results obtained, the common occurrence of a heme-linked functional response of the hemoprotein conformation was suggested.

Animals↗
PubMed2004

Comparison of a combination ferrous fumarate product and a polysaccharide iron complex as oral treatments of iron deficiency anemia: a Taiwanese study.

Despite efforts to improve iron supplements for iron deficiency anemia, there is no consensus on products that balance efficacy, safety and tolerability, and cost. Ferrous products are effective, but they are associated with more gastrointestinal side effects than ferric products. Ferric products tend to have lower absorption. We present results from a 12-week study that randomized 72 people with uncomplicated iron deficiency anemia to receive a ferrous iron supplement (Ferall, a combination of ferrous fumarate with ascorbic acid, folic acid, and cyanocobalamin) or a ferric iron polysaccharide complex (Niferex, ferro-glycine sulfate) plus ascorbic acid. The ferrous product was significantly more effective, the primary and secondary endpoints including changes in levels of hemoglobin and serum ferritin. There was a slightly higher frequency of gastrointestinal side effects in patients taking the ferrous product, but both supplements were well tolerated. No participant withdrew from the study because of side effects. We concluded that the ferrous product is safe and effective for use in uncomplicated iron deficiency anemia. The lack of direct comparison between single-agent ferrous fumarate and the combination ferrous product limited interpretation of results in terms of possible effects due to other components, such as ascorbic acid.

Administration, Oral↗
PubMed1985

Unscheduled DNA synthesis correlated to alkylation of hemoglobin in individuals occupationally exposed to propylene oxide.

Exposure to propylene oxide was determined previously by the degree of alkylation of hemoglobin measured on the histidine residue as N-3-(2-hydroxypropyl) histidine, using blood samples from 8 propylene oxide-exposed employees and 13 unexposed referents. Mononuclear leukocytes isolated from the same blood samples were used to quantify DNA repair proficiency following an in vitro challenge with the carcinogen, N-acetoxy-2-acetylamino-fluorene. Decreases in the DNA repair proficiency index correlated significantly to in vivo exposure levels to propylene oxide (r = -0.64, p less than 0.03). These data suggest a possible short-term biological assay for monitoring the in vivo genotoxic effects of propylene oxide exposure in the human population.

Adult↗
PubMedDate not supplied

[Interaction of riboflavin and hemoproteins with organic free radicals and superoxide anions generated in the ultrasound field].

The reduction of ferricytochrome c to the ferro form in aqueous alcohol solutions in air by the action of ultrasound and the complete inhibition of this process in the presence of superoxide dismutase indicate the generation of superoxide anions. Further exposure to the ultrasonic field leads to a reverse process of oxidation of the cytochrome c ferro form to the ferri form by hydrogen peroxides and organic peroxides. The addition of catalase protects the cytochrome c ferro form from oxidation to the ferri form. The oxidized form of riboflavin effectively interacts with organic free radicals and superoxide anions to produce a leuko form, which is easily oxidized by air oxygen or the ferri forms of hemoglobin and cyt c to form riboflavin and hydrogen peroxide or the ferro forms of heme-containing proteins, respectively. The recurrence of redox reactions in the presence of riboflavin, organic free radicals, and O2 and the ferri forms of heme-containing proteins suggests that riboflavin can play a role of an antioxidant in the organism. It is supposed that, due to interaction with superoxide anions, riboflavin stabilizes the NO level in the organism under conditions of increased superoxide anion generation and (or) decreased superoxide dismutase activity. A possible role of riboflavin in the modulation of toxic and signal pathways of nitrogen oxide is discussed.

Air↗
PubMed1996

In vivo dosimetry of ethylene oxide and propylene oxide in the cynomolgus monkey.

In mammals, including the cynomolgus monkey, a striking difference between the potencies of ethylene oxide (EO)* and propylene oxide (PO) with respect to induction of certain clastogenic effects has previously been observed. In order to clarify to what extent such differences can be ascribed to a difference in detoxification rate, cynomolgus monkeys were administered an equimolar mixture of the two epoxides at two dose levels, and the blood doses were determined by measurement of the degree of alkylation of N-terminal valines in hemoglobin (Hb). For the highest exposure a saturation in the detoxification of PO was evident from a marked increase in adduct level. At the lower exposure, the dose in blood resulting from exposure to PO was about one fourth of that from EO. Although playing a great role, differences in detoxification rate, therefore, cannot fully account for the much lower clastogenic potency of PO, which has been found in earlier studies. Furthermore, the determination of doses in blood gives data on relationship between in vivo dose and exposure dose (accounting for detoxification), with relevance for risk estimation.

Alkylation↗
PubMed2000

A comprehensive structural analysis of hemoglobin adducts formed after in vitro exposure of erythrocytes to butadiene monoxide.

A widely used method for assessing occupational and environmental exposure to 1,3-butadiene involves the detection of hemoglobin adducts formed by the reactive metabolite butadiene monoxide (BMO). This assay employs the N-alkyl Edman method, which was developed to determine adducts formed at the amine group of the N-terminal valine of hemoglobin. Disadvantages of this procedure include its limitation to detecting only one adduct per globin chain, despite the presence of numerous other, and potentially more reactive, nucleophilic amino acids in hemoglobin. The method is also not suitable for determining whether the reaction of BMO occurs at the N-terminal valine of alpha- or beta-globin. The primary goals of the current research are to determine the degree of modification of alpha- and beta-globin chains by BMO and to localize the reactive residues to specific regions of the globin polypeptides. The reaction products after in vitro incubation of C57Bl/6 mouse erythrocytes with BMO were isolated by acid extraction of heme and microprecipitation of globin, followed by the determination of the number and location of adducts by mass spectrometry. The modification degree was monitored by electrospray mass spectrometry, which was used to measure the time- and concentration-dependent formation of BMO-hemoglobin adducts (< or =10 adducts per globin). The results indicate that BMO reacts faster and to a higher degree with alpha-globin than with beta-globin. Structural analysis was performed by peptide mapping of globin peptides after trypsin digestion using liquid chromatography/mass spectrometry. These experiments allowed the localization of BMO-hemoglobin adducts to specific regions within alpha- and beta-globin, and also provided information about their relative reactivity. Interestingly, the initial site of adduct formation on alpha-globin is located near the N-terminal peptide, whereas the initial site on beta-globin is located at the C-terminal region. Collectively, the results establish differences in the reactivities of alpha- and beta-globin toward BMO, demonstrate the formation of multiple adducts at several alpha- and beta-globin sites, and show that the N-terminal valine residues are not the first to be modified by BMO.

Amino Acid Sequence↗
PubMed1991

Preparation and surface characterization of carboxymethylchitin-incorporated submicron bilayer-lipid membrane artificial cells (liposomes) encapsulating hemoglobin.

In view of the desirability to increase the survival time of the lipsome-based artificial red blood cells in vivo, bovine hemoglobin-loaded liposomes (LEHb) are incorporated with a polyanionic polymer, a highly substituted type of carboxymethylchitin (CMC). The liposomes are prepared by a modified Reverse Phase Evaporation technique and then purified using a Sepharose 4B column. A comparative study between experimental techniques for the determination of adsorption efficiency suggests that FT-IR spectroscopy gives a more accurate quantitative adsorption index while the chitinase-based enzymatic assay should be used as a qualitative detection tool. The overall composition of the bilayer(s) can be approximated by that of the natural (RBC) membrane in terms of total lipids and carbohydrates at 87.8% (phospholipids and cholesterol) and 12.2% CMC respectively.

Biocompatible Materials↗
PubMedDate not supplied

[Dose-effect of the administration of ferrous fumarate in aged persons with iron deficiency].

BACKGROUND: Anemia is the most prevalent hematological problem in elderly persons, affecting 14% of the males and 6% of the females of the population over 60 years of age in Mexico City. OBJECTIVE: To determine the effect produced by the prolonged administration of ferrous fumarate in elderly persons with iron deficiency. METHOD: In a population of 178 subjects, aged between 65 to 100 years, iron deficiency was diagnosed in 51 (28.6%), who had serum iron concentrations below 80 micrograms/dL for men and 60 micrograms/dL for women, but only 21 patients (11.8%), accepted to participated in the study. The response to a 6 months oral administration of ferrous fumarate were studied with a daily oral dose of 5 mg/kg of elemental iron. The patients were classified in 3 groups according to the abnormal parameters of iron metabolism (group 1 = 10.9% anemia, group 2 = 28.0% and group 3 = 63.0% anemia). RESULTS: The efficacy of treatment was evaluated by quantification of the changes occurred in serum iron concentrations, hemoglobin, ferritin and transferrin saturation index, at 0, 30, 90 and 180 days of treatment. This study showed that the treatment of oral ferrous fumarate in elderly patients with iron deficiency, produces a quantifiable improvement in measures of iron parameters within 6 months. CONCLUSIONS: The results of this study suggest the usefulness of prolonged treatment with ferrous fumarate in elderly patients with iron deficiency, to avoid therapeutic failure as a consequence of non-compliance as is common in elderly patients.

Age Factors↗
PubMed2006

Fortifying milk with ferrous gluconate and zinc oxide in a public nutrition program reduced the prevalence of anemia in toddlers.

We aimed to assess the efficacy of whole cow's milk fortified with ferrous gluconate and zinc oxide, along with ascorbic acid, in reducing the prevalence of anemia and improving iron status of low income children 10-30 mo of age. Healthy children were randomly assigned to drink 400 mL/d of cow's whole milk, either fortified milk (FM) with 5.8 mg/400 mL of iron as ferrous gluconate, 5.28 mg/400 mL of zinc as zinc oxide, and 48 mg/400 mL of ascorbic acid, or nonfortified milk (NFM) with 0.2 mg iron/400 mL, 1.9 mg zinc/400 mL, and 6.8 mg ascorbic acid/400 mL. Hemoglobin, serum ferritin, soluble transferrin receptors (TfR), and C-reactive protein concentrations were measured at baseline and 6 mo after intervention. The prevalence of anemia declined from 41.4 to 12.1% (P < 0.001), or 29 percentage points, in the FM group; there was no change in the NFM group. Hemoglobin (coefficient = 0.22, P < 0.01) was positively and TfR (coefficient = -0.29, P < 0.001) negatively associated with treatment, controlling for their respective baseline values, age, and gender. Treatment with FM was negatively associated with the likelihood of being anemic (pseudo R(2) = 0.085, P < 0.03) after 6 mo of intervention. Ferrous gluconate added to whole cow's milk as a fortificant along with ascorbic acid is efficacious in reducing the prevalence of anemia and in improving iron status of Mexican toddlers. The results of this study lead to broadening a subsidized FM distribution program to 4.2 million beneficiary children 1-11 y of age in Mexico.

Anemia, Iron-Deficiency↗
PubMed1994

Influence of body iron stores on the serum erythropoietin concentration in hemodialyzed patients.

The influence of body iron stores on the concentration of serum erythropoietin was studied in 48 hemodialyzed patients not receiving human recombinant erythropoietin, androgens or iron supplements. The serum erythropoietin concentration was 11.6 +/- 10.4 mIU/ml. There was no correlation between the serum erythropoietin and the hematocrit or hemoglobin concentration; however, there was a correlation between the serum erythropoietin and the log of serum ferritin (r = -0.5699, p < 0.01). Serum erythropoietin levels were higher in the 18 ferropenic patients (serum ferritin < 50 ng/ml) than in the 30 patients with normal serum ferritin concentration (18 +/- 13.8 vs. 7.8 +/- 4.7 mIU/ml, p < 0.01). The administration of intravenous iron to the ferropenic patients resulted in a reduction in serum erythropoietin independent of the response of the anemia (18 +/- 13.8 basal and 7.9 +/- 6.5 mIU/ml at 4 weeks, p < 0.01). Our data would suggest that the concentration of erythropoietin in hemodialyzed patients is influenced by the serum ferritin level.

Adult↗
PubMed2002

Pharmacological correction of hypothermic P(50) shift does not alter outcome from focal cerebral ischemia in rats.

Hypothermia decreases the arterial PO(2) at which hemoglobin is 50% saturated (P(50)), increasing hemoglobin O(2)-binding affinity. We used RSR13, a synthetic allosteric modifier of hemoglobin that increases P(50), to study the role of altered hemoglobin O(2)-binding affinity in mild hypothermic neuroprotection. RSR13 (150 mg/kg iv) restored P(50) to normothermic values. Rats underwent 70 min of middle cerebral artery occlusion (MCAO) at 30.0, 34.0, or 37.5 degrees C with hemoglobin saturation held at 98-100%. The 34.0 degrees C group received RSR13 or vehicle before ischemia. After 7 days of recovery, infarct volumes were reduced in all hypothermic groups, without evidence of a detrimental effect on infarct size or neurological score as a result of P(50) correction. To examine for a beneficial effect of P(50) correction, ischemia duration was increased to 120 min in rats maintained at 34.0 degrees C. Correction of P(50) by RSR13 did not alter cerebral infarct sizes or neurological scores. The decrease in P(50), caused by mild hypothermia, could not be associated with infarct size or neurological deficit resulting from ischemic brain hypoxia in rats.

Aniline Compounds↗
PubMed2000

Chymase mediates mast cell-induced angiogenesis in hamster sponge granulomas.

We investigated the contribution of mast cell chymase in mast cell-dependent angiogenesis using the hamster sponge-implant model, where angiogenesis in the granulation tissue surrounding the subcutaneously implanted sponge was evaluated by measuring the hemoglobin content. Daily local injection of compound 48/80 (3-100 microg/site/day), a potent mast cell activator, induced formation of granulomas and angiogenesis in time- and dose-dependent manners. This angiogenic response was inhibited by chymase inhibitors including chymostatin (> or = 1 nmol/site/day), soybean trypsin inhibitor (SBTI; > or = 1.4 nmol/site/day) and lima bean trypsin inhibitor (LBTI; > or = 3.3 nmol/site/day), but not by a tryptase inhibitor like leupeptin (> or = 700 nmol/site/day). Although pyrilamine (> or = 2,580 nmol/site/day), a histamine H1 receptor antagonist, and protamine (300 microg/site/day) also inhibited angiogenesis, these effects were much less pronounced than those by chymase inhibitors. Furthermore, antigen-induced angiogenesis in hamsters pre-sensitized with ovalbumin was also inhibited by the chymase inhibitors by 60-70%. Our results suggest that chymase is a major mediator in mast cell-mediated angiogenesis.

Animals↗
PubMed2006

Relationships between biomarkers of exposure and toxicokinetics in Fischer 344 rats and B6C3F1 mice administered single doses of acrylamide and glycidamide and multiple doses of acrylamide.

Acrylamide (AA) is a widely studied industrial chemical that is neurotoxic, mutagenic to somatic and germ cells and carcinogenic in rodents. AA is also formed in many commonly consumed starchy foods during cooking. Our previous toxicokinetic investigations of AA and its important genotoxic metabolite, glycidamide (GA), in rodents showed that AA is highly bioavailable from oral routes of administration, is widely distributed to tissues and that the dietary route, in particular, favors metabolism to GA. Measurements of DNA adducts in many tissues supported the hypothesis that AA is carcinogenic in rodent bioassays through metabolism to GA. The current investigation describes the development and validation of methodology for measuring hemoglobin (Hb) adducts with AA and GA in the same rodents previously used for toxicokinetic and DNA adduct measurements. The goal was to investigate possible relationships between these circulating biomarkers of exposure and serum toxicokinetic parameters for AA and GA and tissue GA-DNA adducts in rodents from both single and repeated dosing with AA. Significant correlations were observed between GA-Hb and liver GA-DNA adducts for either single or multiple dosing regimens with AA. Using available GA-Hb adduct data, empirical and allometric relationships permitted estimation of liver DNA adducts in humans in the range of 0.06-0.3 adducts/10(8) nucleotides. This approach may prove useful in extrapolating human cancer risks from findings in rodent bioassays.

Acrylamide↗
PubMed1991

Randomized, placebo-controlled trial of iron supplementation in infants with low hemoglobin levels fed iron-fortified formula.

In spite of the declining prevalence of iron-deficiency anemia, a large proportion of low-income infants have "low-normal" (11-11.5 g/dL) and "low" (less than 11 g/dL) hemoglobin (Hgb) values. Because most of these infants are fed iron-fortified formulas, it was of interest whether additional iron supplementation would enhance Hgb values. A cohort of 334 healthy, inner-city, minority, 6-month-old infants, fed iron-fortified formulas, with Hgb values ranging from 9 to 11.5 g/dL, participated in a double-blind, randomized, placebo-controlled trial of supplemental iron at 0, 3, and 6 mg/kg per day for 3 months. Hemoglobin values increased significantly with age, regardless of assignment to placebo or supplemental iron (means for the entire cohort: 6 months 10.9 g/dL, 8 months 11.2, 10 months 11.3, and 12 months 11.4). The proportion of "responders" (Hgb level increased greater than or equal to 1 g/dL) was 34% and did not differ significantly by placebo or iron dose. There were no significant differences in mean corpuscular volume or levels of erythrocyte porphyrins or serum ferritin between treatment groups. The implications of this clinical trial are twofold: (1) screening healthy infants fed iron-fortified formula at the age of 6 months is not justified, regardless of socioeconomic status; (2) the clinical practice of routinely treating low-income, "low-Hgb" infants with iron supplementation, without regard to dietary considerations, is unwarranted.

Anemia, Hypochromic↗
PubMed2003

Evaluation of iron bioavailability from bonito dark muscle using anemic rats.

The bioavailability of iron from ferrous sulfate (FeII-S), heme iron prepared from hemoglobin (HIP), and bonito dark muscle (BDM) was assessed in anemic rats using a hemoglobin regeneration efficiency (HRE) method. Freeze-dried BDM (FD), boiled and freeze-dried BDM (B/FD), and boiled and smoke-dried BDM (B/SD) were used as BDM source. Rats were made anemic by feeding on an iron-deficient diet for 28 days. To replete their iron levels, anemic rats were then fed on a diet containing iron at a level of 17 ppm for 14 days. Rats receiving FeII-S gained significantly more weight and had greater food intake and higher HRE compared to the other four groups. The bioavailability of iron from HIP was poor compared with that from FeII-S and BDM. When the HRE of rats fed FeII-S was 100, that of rats fed BDF was approximately 80. These results suggest that BMD is an effective dietary source of iron.

Anemia, Iron-Deficiency↗