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PubMed1979

Leucomalachite green assay for free hemoglobin in serum.

A new colorimetric assay for the determination of serum free hemoglobin utilizing the noncarcinogenic compound leucomalachite green is described. The reaction is complete in 8 min, with the resulting color stable for at least 30 min. The absorption maximum for the leucomalachite green reaction product was observed at 617 nm. Precision studies at 50 and 300 mg/l free hemoglobin concentrations resulted in within-run variations of 1.9 and 1.7%, while the day-to-day variations were 6.9 and 4.0%, respectively. Accuracy studies at concentrations of 50, 150 and 300 mg/l resulted in recoveries of 88, 95 and 98% of theoretical values.

Aniline Compounds↗
PubMed1989

Chlorophenoxy acetic acid derivatives as hemoglobin modifiers and tumor radiosensitizers.

We have studied the influence of the antilipidemia drug, clofibrate, and several structurally related analogs on the binding affinity of hemoglobin for oxygen and the radiation sensitivity of the SCCVII/St carcinoma in the mouse. Several compounds in this class reduced hemoglobin affinity in vivo; and two of these, ML1024 (etophyline clofibrate) and ML1037, were at least as effective as clofibrate at reducing hemoglobin affinity and much less toxic. When given orally at a dose of 4.1 m mole/Kg, 1/2-2 hrs before 20 Gy X rays, clofibrate gave radiosensitization in the SCCVII/St tumor equivalent to a 40-fold reduction in hypoxic fraction. ML1024 and ML1037 at a dose (3.0 m mole/Kg), which had a similar effect on hemoglobin, gave much less sensitization of the tumor. Only ML1024 produced a statistically significant effect, equivalent to a four-fold reduction in hypoxic fraction. We conclude that there are several clofibrate analogs which in relation to their toxicity are much better hemoglobin modifiers than the parent compound. They do not, however, show the same radiosensitizing effects, leading us to believe that mechanisms other than changes in hemoglobin/oxygen binding must also be involved.

Animals↗
PubMedDate not supplied

[Study of normal human fetal and adult hemoglobins by Mössbauer spectroscopy].

Human normal fetal and adult hemoglobins were investigated by Mössbauer spectroscopy. The differences discovered in quadrupole splitting are connected with distinctions in protein molecular structures. An approximation of Mössbauer spectra of hemoglobins in supposition of nonequivalence of Fe(II) electronic structure in alpha-, beta- and gamma-subunits in tetramers was proposed. Qualitative analysis of the relationship of Fe(II) electronic structure, molecular structure of the active site and functionality of hemoglobin was carried out.

Ferrous Compounds↗
PubMed2000

Mechanism of site-directed protein cross-linking. protein-directed selectivity in reactions of hemoglobin with aryl trimesates.

Site-directed cross-linking of hemoglobin has become an efficient way to produce a structurally defined altered protein with desirable functional properties. The reagent trimesoyl tris(3, 5-dibromosalicylate) (1) introduces a bis amide cross-link derived from the epsilon-amino groups of the side chains of the two beta-Lys-82 residues in human hemoglobin. The basis of its specificity was investigated using a set of analogues of 1 (2-12). There are marked differences in the reaction patterns of these compounds with amino groups in hemoglobin compared to reactions with n-propylamine. The compounds that effectively modify the protein contain a carboxyl group ortho to the phenolic oxygen of the ester, while materials with meta or para carboxyl groups give little or no reaction. In contrast, the reactions with n-propylamine are slowest with the ortho carboxyl materials. Addition of the unreactive compound 5 to a solution containing hemoglobin reduces the ability of 1 to modify the protein, showing that the unreactive compound binds but does not react. On the basis of these observations and the known reaction patterns of salicylates, it is clear that the environment in the protein controls the reaction, regardless of the inherent reactivity of the reagent. We propose that the carboxyl group positions the reagent critically within the protein. Only the ortho arrangement permits transfer of the acyl function to the nucleophile.

Chromatography, High Pressure Liquid↗
PubMed1954

The effect of formaldehyde on the oxygen equilibrium of hemoglobin.

1. When formaldehyde (0.10 M) is added to solutions of human hemoglobin, the oxygen affinity of the hemoglobin increases considerably (more than tenfold near pH 7). The interaction between hemes of the same hemoglobin molecule decreases, as shown by a drop in the value of n in Hill's equation from 2.9 to 1.5 or less. 2. In the presence of formaldehyde, both n and the oxygen pressure for half-saturation fall gradually as the pH rises in the range from pH 6.2 to 7.2. 3. Some of the effect of formaldehyde on the oxygen equilibrium may be due to combination with sulfhydryl groups of the protein, but nitrogenous groups are probably also involved.

Formaldehyde↗
PubMed2002

The interplay between heme iron and protein sulfhydryls in the reaction of dimeric Scapharca inaequivalvis hemoglobin with nitric oxide.

The homodimeric hemoglobin from the mollusk Scapharca inaequivalvis possesses a single reactive cysteine residue per monomer, Cys92, which is located in the subunit interface in the vicinity of the heme group. The interplay between the heme iron and Cys92 towards the reaction with NO has been investigated by the combined use of electrospray mass spectrometry, FTIR and UV-Visible spectroscopy. When the ferrous liganded or unliganded protein reacts with free NO in solution Cys92 is not modified, but undergoes nitrosation when the hemoglobin is exposed to the nitric oxide releaser S-nitrosocysteine. When the ferric protein reacts with free NO under anaerobic conditions the heme iron is reduced and Cys92 is nitrosated. At variance with other hemeproteins investigated to date, in Scapharca HbI the heme-iron NO driven reduction is not accompanied by the formation of a ferric iron nitrosyl intermediate in detectable amounts. The results are consistent with the hypothesis that the nitrosating agent is the NO(+) species, which is generated during the NO driven reduction of the ferric heme iron. The possible reaction mechanism is discussed in comparison with recent findings on human hemoglobin and myoglobin.

Animals↗
PubMed1982

Chemical modification of hemoglobin in intact whole cells: morphological studies by scanning electron microscope.

1. Whole blood was incubated in physiological conditions with a variety of modifiers capable of modifying hemoglobin. Some of these compounds have been considered as therapeutic agents for certain hemoglobinopathies such as sickle-cell disease. 2. The extent of modification on hemoglobin was estimated by electrophoresis and the red-cell morphology by scanning electron microscope. 3. Results indicated that carbamyl phosphate, aspirin and glutaryl-salicylamide had no observable effect, whereas cross-linkers in general produced drastic changes in red-cell morphology. 4. Dibromoaspirin, a very effective acetylating agent, produced abnormalities even in concentrations as low as 1 mM.

Anemia, Sickle Cell↗
PubMed1988

A 119Sn Mössbauer spectroscopic study on the interaction of dimethyltin (IV) derivatives with rat hemoglobin, and of related model systems in aqueous solution.

In the context of a study of the molecular basis of the antileukemia (murine) activity of diorganotin (IV) compounds, the interaction with rat hemoglobin (selected as a model protein) of the representative terms dimethyltin dichloride, dimethyltin glycylglycinate (Me2SnGlyGly), and dimethyltin L-cysteinate (Me2Sn-Cys) has been investigated by 119Sn Mössbauer spectroscopy. In order to possibly determine the reaction pathway, aqueous model systems in Hepes buffer at pH 7.4 were also considered. The structural characteristics of reactants and products were advanced on the basis of semiempirical calculations of Mössbauer nuclear quadrupole splitting parameters, delta E, by the point-charge model approach. In aqueous Hepes at pH 7.4, evidence was obtained for the formation of the five-coordinated species, trigonal bipyramidal type (tbp), Me2Sn(OH)2.Hepes(II), Me2Sn(OH)(GlyGly).Hepes(III), and Me2Sn(OH)Cys(IV) (see Fig. 1). Equatorial groups or atoms would be the Me radicals, as well as OH, N(peptide), and S(thiol), respectively. Hepes would coordinate to tin in axial position through the tertiary amino nitrogen, while cysteine would behave as a bidentate chelating agent, with an axially located amino group. Species (II), (III), and (IV) react with cysteine in aqueous Hepes at pH 7.4, yielding Me2Sn(OH)Cys(IV), as well as Me2SnCys2(V), where tin would be embedded into a tbp structure due to one cysteine probably chelating (equatorial S thiol and axial amino nitrogen), and one monodentate through S thiol. Species (II), (III), and (IV) react analogously with rat hemoglobin, primarily through the S thiol of a cysteine side chain, yielding pellets where the environment of tin could be tetrahedral, such as in Me2Sn(OH)(S thiol), (VI), and tetrahedral (IX) or tbp (V) in Me2Sn(Cys)(S thiol), where Cys would act either as chelating or monodentate. Further reaction of (VI) and (IX) could involve imidazole nitrogen atoms, N het, of histidine side chains, forming tetrahedral Me2Sn(S thiol)(N het), (VIII), or tbp Me2Sn(OH)(S thiol)(N het), (VII), and Me2Sn(Cys)(S thiol)(N het), (V) (see Figs. 1 and 5).

Animals↗
PubMed2002

Severe anemia after gastrointestinal hemorrhage in a Jehovah's Witness: new treatment strategies.

OBJECTIVE: Management of severe anemia in a critically ill Jehovah's Witness is challenging. In the past, conservative therapy was the only option available to the practitioner. Recently, new interventional treatment strategies have become available, including human and bovine hemoglobin substitutes and high-dose recombinant human erythropoietin. DESIGN: Case report. SETTING: Intensive care unit in a quaternary care center. PATIENT: A patient with severe, life-threatening anemia caused by gastrointestinal hemorrhage who refused all blood products on religious grounds. INTERVENTION: Bovine hemoglobin substitute and high-dose recombinant human erythropoietin. CASE STUDY: A 50-yr-old Jehovah's Witness presented with massive upper gastrointestinal hemorrhage; initial hemoglobin was 3.5 g/dL. Endoscopy revealed a prepyloric ulcer, and hemorrhage control was achieved by epinephrine injections into the peri-ulcer mucosa. Despite control of hemorrhage, the patient became hemodynamically unstable. A total of 7 units of a bovine hemoglobin-based oxygen carrying compound (HBOC-201) was administered to enhance the patient's oxygen delivery. High-dose recombinant human erythropoietin was administered daily (500 units/kg). Hemoglobin levels were initially maintained and then slowly increased to a maximum of 7.6 g/dL on day 24 of therapy. CONCLUSION: This case demonstrates that the concurrent administration of hemoglobin-based oxygen carriers and recombinant human erythropoietin in severe, life-threatening anemia (hemoglobin, 3.5 g/dL) was associated with patient survival and a significant increase in hemoglobin to 7.6 g/dL, without the administration of allogeneic blood. Hemoglobin-based oxygen carriers can adequately serve as initial therapy to maintain tissue oxygen delivery while awaiting the maximal effect of recombinant erythropoietin on bone marrow red blood cell production. High-dose recombinant human erythropoietin offers these patients the best chance for normalization of hematocrit and survival in the long term.

Anemia↗
PubMed1999

Apheresis of plasma compounds as a therapeutic principle in severe sepsis and multiorgan dysfunction syndrome.

During sepsis there is an increase in the plasma content of several compounds, e.g., bacterial toxins, cytokines, cell debris, free hemoglobin and myoglobin. In blood, these compounds activate various cascade systems, which in large amounts or in more vulnerable patients lead to a disseminated intra-vascular coagulopathy (DIC) with multiorgan dysfunction syndrome (MODS) and death, despite conventional intensive care unit therapy. Therapeutic attempts to reverse these conditions have so far been of limited benefit. These effects have mainly been focused on lowering the blood concentration of single substances such as tumor necrosis factor. By the use of low-and high-flux hemodialysis filters, usually only small amounts of these substances are removed. By the use of plasmapheresis or plasma exchange, the extent of removal is considerably increased. The efficacy varies between the techniques (centrifugation vs. filtration or adsorption) and has also different influences on e.g. the complement system. This report describes these techniques and the therapeutical possibilities given by them. In small trials, blood or plasma exchange has been used as rescue therapy in critically ill patients with a progressive MODS and DIC. A survival of about 80% of the patients has been reported in these studies and the use of combined therapy will be discussed. Controlled trials are required in this field.

Humans↗