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At least 91 records · Page 5Linked to original sources
PubMed1998

The form of iron oxide deposits in thalassemic tissues varies between different groups of patients: a comparison between Thai beta-thalassemia/hemoglobin E patients and Australian beta-thalassemia patients.

Mössbauer spectra of 12 beta-thalassemia/hemoglobin E spleen samples from Thai patients who had not received multiple blood transfusions and chelation therapy and seven beta-thalassemia spleen samples from Australian patients who had received multiple blood transfusions and chelation therapy were recorded with sample temperatures of 78 K. Each spectrum was found to consist of a superposition of a relatively intense central doublet characteristic of high-spin Fe(III), a low intensity sextet of peaks due to magnetic hyperfine-field splitting, and occasionally a doublet that could be attributed to heme iron. A significant (P=0.01) difference (Kolmogorov-Smirnov statistic of 0.71) between the distributions of sextet signal intensity as a fraction (Fs) of the total non-heme iron Mössbauer spectral signal for the two groups of patients was detected. The distribution of Fs for the Thai beta-thalassemia/hemoglobin E spleens had a mean value of 0.128 (S.D. 0.035) while that for the Australian beta-thalassemia spleens had a mean of 0.27 (S.D. 0.12). No significant difference between the distributions of non-heme iron concentrations in the tissues for the two groups of patients was detected by atomic absorption spectrometry. This study shows that the Australian beta-thalassemia patients had a higher fraction of their non-heme spleen iron in a goethite-like form than the Thai beta-thalassemia/Hb E patients.

Chelation Therapy↗
PubMed1987

High-dose carbonyl iron for iron deficiency anemia: a randomized double-blind trial.

To determine if high doses of oral iron could shorten the duration of therapy necessary to treat Fe deficiency anemia, high-dose Fe 600 mg three times per day (given as nontoxic carbonyl Fe) was compared with standard ferrous sulfate 60 mg Fe++ three times per day in a randomized, double-blind, 3-wk trial involving 36 female blood donors with mild Fe deficiency anemia. In animal studies, both forms of Fe have similar bioavailability when administered in equal amounts. High-dose carbonyl Fe was well tolerated with gastrointestinal side effects similar those observed with standard FeSO4 therapy. The 10-fold larger amount of Fe resulted in a mean 1.5-fold increase in estimated Fe absorption. Both regimens corrected anemia but neither replenished storage Fe. These results suggest that the principal advantage to the use of carbonyl Fe would derive from its safety rather than from the large doses that can be given.

Adolescent↗
PubMedDate not supplied

Scavenging effects of hemoglobin and related heme containing compounds on nitric oxide, reactive oxidants and carcinogenic volatile nitrosocompounds of cigarette smoke. A new method for protection against the dangerous cigarette constituents.

The present study refers to the utilization of hemoglobin and related heme containing substances in scavenging noxious compounds contained in the gas phase of cigarette smoke (e.g. nitric oxide (NO), nitrogen oxides (NOx), hydrogen peroxide (H2O2), carbon monoxide (CO), aldehydes, trace elements and carcinogenic nitrosocompounds) which were up to today insufficiently retained by conventional cigarette filters. Hemoglobin impregnated conventional cigarette filters were capable of withholding the above noxious components of the cigarette smoke up to 90%. Similar results were also obtained when solid hemoglobin was sandwiched between two common filters so that all cigarette smoke drawn through the filter comes into contact with the active groups of the hemoglobin molecules (Fe3+, Fe2+, -SH, -NH2). The present study also shows that noxious oxidants contained in cigarette smoke can be retained and neutralized by appropriate scavengers like: a) substances which contain stereospecifically bound iron, b) substances which contain porphyrin ring with iron (e.g. protoporphyrin), c) substances which contain porphyrin ring that does not necessarily contain iron, d) substances which contain porphyrin ring complexed with other metals (e.g. Cu2+, Mg2+). We have also demonstrated that rat alveolar macrophages challenged by cigarette smoke release both superoxide (O2-) and NO the interaction of which resulted in the formation of peroxynitrite (ONOO-). Alveolar macrophages continue to release NO/ONOO- for 30 min following two or three puffs of smoke. Similar results were also obtained in experiments with human volunteers. It was shown that during cigarette smoking the ratio of NO/ONOO- in the inhaled smoke was 1:0.5 while in the exhaled smoke was 1:9, due to secondary redox reactions taking place in the lung resulting in the ONOO- formation. When smokers inhaled cigarette smoke passed through a conventional filter containing hemoglobin, a 70% reduction of both NO and ONOO- in their exhaled cigarette smoke was observed. All findings prove conclusively that, alveolar macrophages exposed to cigarette smoke evoke a dramatic increase of NO, NOx, ONOO- and H2O2 inside the lung. These substances stimulate by a positive feed back mechanism the alveolar macrophages and perhaps even endothelium of the alveolar vessels, to produce more oxidants resulting in lung damage.

Anticarcinogenic Agents↗
PubMed1984

Kinetics of partitioning and binding of digoxin and its analogues in the subcompartments of blood.

The kinetics of digoxin and analogues (metabolites) in the subcompartments of blood, erythrocytes and plasma, were first order and concentration independent. The rate and extent of red blood cell partitioning of the tested compounds were, according to first-order kinetics, identical in the presence and absence of structurally related compounds and dependent on lipophilicity and temperature; red blood cell penetration was a reversible process. Erythrocyte partitioning of digoxin and its analogues was postulated to be by passive diffusion. There was significant intracellular binding of the compounds, and hemoglobin was the major ligand. The kinetics of red blood cell partitioning of the individual compounds were fitted according to a closed two- or three-compartment modeL. The latter indicated the existence of two kinetically separable compartments within the red blood cells. Model-independent mean transit times of red blood cell-plasma water partitioning of the compounds depended largely on the lipophilicity and were a thousand times greater for the least lipophilic analogues than for the most lipophilic derivatives. Red blood cell partitioning of digoxin and its metabolites under in vivo and in vitro conditions, were equivalent. Plasma protein binding of the tested compounds was concentration independent, unaltered in the presence of the analogues, and temperature independent between 24 degrees C and 37 degrees C. Binding to albumin in buffer solution was significantly larger than to albumin in plasma for all the compounds. Binding of digoxin and its analogues to albumin in buffer solution increased with increasing lipophilicity of the compounds.

Albumins↗
PubMed1982

Nutritional iron and dopamine binding sites in the rat brain.

Iron-deficiency (ID) anemia in man is associated with neurological disorders and abnormal behavior. Rats made nutritionally iron-deficient have markedly diminished behavioral responses to centrally-acting drugs (amphetamine and apomorphine) which affect monoaminergic systems. ID has no effect on either the levels of monoamines or on the activities of monoamine-metabolizing enzymes in the brain. We have investigated the possibility that ID may affect postsynaptic events at the level of receptor by measuring the specific binding sites of several neurotransmitters in different brain areas. The results clearly show that ID causes a significant (40-60%) reduction of the DA D2 binding sites in the caudate. DA-sensitive adenylate cyclase, alpha- and beta-adrenergic, muscarinic cholinergic and the benzodiazepine binding sites were not affected by ID. The effects of ID on DA D2 binding sites and the behavioral responses to apomorphine can be reversed when iron-deficient rats are placed for 8 days on an iron-deficient diet supplemented with iron. Chronic hemolytic anemia produced by repeated phenylhydrazine injections caused no change in serum iron and had no effect on either apomorphine-induced hyperactivity or 3H-spiroperidol binding in the caudate. Since the highest concentration of iron is found in DA-rich brain areas, it is possible that iron may be crucial to either the synthesis or coupling of the DA D2 binding site. The possibility that the DA supersensitivity induced by neuroleptics may be related to iron metabolism in the brain has been investigated.

Anemia, Hemolytic↗
PubMed1992

Artificial blood substitutes.

Investigations directed toward the development of an effective artificial blood substitute are continuing as concerns remain regarding the safety and adequacy of the nation's blood supply. Perfluorochemical compounds, modified hemoglobin solutions, and microencapsulated hemoglobin represent the major areas of research. If a successful red cell substitute can be developed, many problems inherent in current blood transfusion practices could be alleviated, particularly in emergency situations.

Blood Substitutes↗
PubMed1993

Effect of local change in O2 saturation of hemoglobin on cerebral vasodilation from hypoxia and hypotension.

We tested the effect of certain newly synthesized allosteric modifiers of hemoglobin on the dilation induced by arterial hypoxia, arterial hypotension, and arterial hypercapnia in cerebral arterioles of anesthetized cats equipped with cranial windows for the observation of the cerebral microcirculation. The allosteric modifiers of hemoglobin are isomers of 2-(aryloxy)-2-methylpropionic acid. They shift the oxygen dissociation of hemoglobin to the right, thereby facilitating the local release of oxygen. When these compounds were applied topically by superfusion at a rate of 1 ml/min in a concentration of 0.1 mM, they had no significant effect on baseline arteriolar diameter but reduced significantly the vasodilation from arterial hypoxia and arterial hypotension. They did not influence the vasodilation from arterial hypercapnia. Spectrophotometric measurements of optical densities from pial veins 50-80 microns in diameter indicated that the superfusion with the allosteric compounds reduced hemoglobin oxygen saturation both during room air breathing and during hypoxia. We conclude that the vasodilations from arterial hypoxia and arterial hypotension are mediated by local oxygen-dependent mechanisms. The allosteric modifiers of hemoglobin may be useful as tools in investigating oxygen-dependent mechanisms.

Animals↗
PubMed1983

Inhibition of the growth of Plasmodium falciparum in vitro by covalent modification of hemoglobin.

Antimalarial effects might be expected from compounds that modify hemoglobin. Dibromoaspirin and bis(dibromosalicyl) diesters decrease gelation of hemoglobin by specific covalent modification (acetylation and crosslinking) of this protein but do not interfere with oxygen transport. These compounds were toxic to malaria parasites when continuously present in culture, as were drugs with similar pharmacological effects such as indomethacin, ibuprofen, and phenylbutazone. Aspirin and acetaminophen were much less effective. When erythrocytes were pretreated with these compounds prior to parasite exposure, only dibromoaspirin and dibromosalicyl diesters prevented parasite development. The modified hemoglobin was highly resistant to digestion by cathepsin D and parasite proteases, suggesting that covalent modifications of hemoglobin that do not disrupt normal hemoglobin function have antimalarial effects.

Animals↗
PubMed1984

Measurement of intracellular pH and deoxyhemoglobin concentration in deoxygenated erythrocytes by phosphorus-31 nuclear magnetic resonance.

Deoxygenation of erythrocytes produced marked changes in their 31P nuclear magnetic resonance spectra in the superconducting spectrometer. Most significantly, all intracellular and extracellular phosphates underwent downfield shifts. In fully deoxygenated blood the extracellular phosphates showed downfield shifts that were dependent upon packed cell volume, when added pyrophosphate was used as a measure of extracellular chemical shift behavior. This effect on extracellular signals was attributed to the paramagnetic contribution of deoxyhemoglobin to the "bulk" magnetic susceptibility of the red cell suspension. Line broadening was observed in deoxygenated whole cell systems but not in hemolysates, as a result of paramagnetic susceptibility gradients across the cell membrane. The degree of downfield shift upon deoxygenation was of different magnitude for each intracellular phosphate [2-P of 2,3-diphosphoglycerate (2,3-DPG) greater than 3-P of 2,3-DPG greater than inorganic phosphate greater than ATP phosphates], independent of packed cell volume but dependent on the degree of deoxygenation of hemoglobin. When deoxygenation shift effects in adult cells were compared to those of cord blood cells containing 70% fetal hemoglobin, it was found that 45% of the 2,3-DPG shift effects were attributable to binding of that compound to hemoglobin. By use of a nonphysiologic phosphate analogue, methylphosphonate, as an internal reference, it was found that an increase in pH of deoxy cells contributed to the downfield shift of inorganic phosphate. In hemolysates, the methylphosphonate - inorganic phosphate chemical shift difference was found to be pH dependent, with a sensitivity of (-) 0.39 pH unit/ppm, independent of the hemoglobin oxygenation state.

2,3-Diphosphoglycerate↗