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PubMed1983

Encapsulation of hemoglobin in phospholipid vesicles.

Hemoglobin has been encapsulated in phospholipid vesicles by extrusion of hemoglobin/lipid mixtures through polycarbonate membranes. This technique avoids the use of organic solvents, sonication, and detergents which have proven deleterious to hemoglobin. The vesicles are homogeneous, with a mean size of 2400 A as determined by photon correlation spectroscopy. The encapsulated hemoglobin binds oxygen reversibly and the vesicles are impermeable to ionic compounds. Hemoglobin encapsulated in egg phosphatidylcholine vesicles converts to methemoglobin within 2 days at 4 degrees C. By contrast, when a mixture of dimyristoyl phosphatidylcholine, cholesterol and dicetyl phosphate is used there is no acceleration in methemoglobin formation, and the preparation is stable for at least 14 days at 4 degrees C.

Animals↗
PubMed2000

High-performance liquid chromatography coupled to enzyme-amplified biochemical detection for the analysis of hemoglobin after pre-column biotinylation.

The determination of proteins with enzyme-amplified biochemical detection (EA-BCD) coupled on-line with high-performance liquid chromatography (HPLC) is demonstrated. The EA-BCD system was developed to detect biotin-containing compounds. Hemoglobin, which was used as a model compound, was biotinylated prior to sample introduction. Several biotinylation parameters, such as pH and removal of excess biotinylation reagent, were investigated. After biotinylation samples were introduced to HPLC followed by EA-BCD. To the HPLC effluent, alkaline phosphatase label streptavidin (S-AP) was added, which possesses high affinity to biotin and biotin-containing compounds. Excess S-AP was removed by means of an immobilized biotin column followed by substrate addition. The non-fluorescent substrate is converted to a highly fluorescent product by the enzyme label. A detection limit of 2 femtomol biotinylated Hb was achieved with good reproducibility and linearity. However, biotinylation at low analyte concentration suffers from low yield due to slow reaction kinetics. Finally, Hb was successfully extracted from urine with a recovery of 94%.

Alkaline Phosphatase↗
PubMedDate not supplied

Sustained endothelial dependent dilation in pial arterioles after crosslinked hemoglobin transfusion.

Hemoglobin is known to bind nitric oxide (NO) with high affinity. Plasma-based hemoglobin may provide a more effective sink for NO than red cell-based hemoglobin because of a closer and consistent proximity to the endothelium. Despite the known endothelial tight junctions that exist in cerebral vessels, plasma-based hemoglobin may inhibit NO-derived vasoreactive mechanisms in brain. If so, the response to endothelial and non-endothelial dependent vasodilator substances should be affected. In pentobarbital anesthetized cats, we tested this hypothesis by measuring the pial arteriole blood vessel diameter using aa cranial window before and after systemic transfusion of a human crosslinked hemoglobin compound. We than topically applied solutions of endothelial dependent or endothelial independent vasodilators and an NO synthase inhibitor to the surface of the brain within the window and remeasured the arteriole size. Topical acetylcholine (Ach) increased diameter in all arteriole sizes. The corresponding increases in diameter to Ach in time control eats (32% hematocrit) and in albumin transfused cats (18% hematocrit) were similar to those in hemoglobin transfused cats. Likewise, size-dependent dilation to SIN-1 in the hemoglobin group was similar to that in the control and albumin groups. The pial arteriole response to adenosine diphosphate (ADP) and sodium nitroprusside (SNP) also increased arteriole diameter in small, medium and large arterioles. Superfusion with L-nitroarginine to inhibit NO synthase markedly reduced the dilator response to Ach and ADP but not to SIN-1 or SNP. Thus, prior crosslinked hemoglobin transfusion does not interfere with vasodilator responses to either Ach, ADP, SIN-1 or SNP. When dilute solutions of crosslinked hemoglobin were superfused abluminally in the cranial window in anesthetized but non-transfused animals, the dilator response to Ach was unchanged at 10(-4)M hemoglobin, was attenuated at 10(-7) and 10(-6)M hemoglobin, and was completely blocked at 10(-5)M hemoglobin. This finding implies negligible permeation of the blood-brain barrier by crosslinked hemoglobin acutely after the transfusion.

Acetylcholine↗
PubMed1997

Effect of organotin compounds on trout hemoglobins.

The stability of trout hemoglobin was examined in the presence of some organotin compounds. Tributyltin chloride (TBTC) and triphenyltin chloride (TPTC) protect HbI most efficently from the oxidation. On the other hand, the same compounds accelerate the precipitation process in HbIV to a great extent. Parahydroxymercuribenzoate (PMB), an agent blocking free SH-groups of the protein, abolished the ability of TPTC to decrease the oxidation rate of HbI.

Animals↗
PubMed1991

Interleukin-1 beta release from human peripheral blood monocytes associated with phagocytosis of carbonyl-iron or erythrocytes.

Interleukin-1 beta (IL-1 beta) release from human peripheral blood monocytes during the incubation with carbonyl-iron or sheep red blood cells was investigated. The incubation of purified monocytes with carbonyl-iron or sheep red blood cells enhanced IL-1 beta release, while their compounds, hemoglobin, globin and ferric citrate did not. The mechanisms of IL-1 beta release by carbonyl-iron or sheep red blood cells may be related to their phagocytosis, as non-phagocytic monocytes did not release IL-1 beta.

Enzyme-Linked Immunosorbent Assay↗
PubMed1984

A blood substitute from hydroxyethyl starch and hemoglobin.

One method to increase the retention time of hemoglobin (Hgb) is to react it with a hydroxyethyl starch (HES) molecule. To examine this hypothesis, polymer-bound hemoglobin compounds were synthesized by the dialdehyde route. The electrophoretic mobility patterns indicate complete binding of the Hgb. Preliminary exchange-transfusion experiments in rates showed that they could survive for at least 10 h at Hct less than 10% when transfused with 6% HES-Hgb solutions. The retention time of the Hgb in the urine was increased to 12 h with these new polymers.

Animals↗
PubMed1990

Detection of the hemoglobin E mutation using the color complementation assay: application to complex genotyping.

The color complementation assay (CCA) is a method of allele-specific DNA amplification by which competitive priming and extension of fluorescently labeled oligonucleotide primers determine the color of DNA amplification product. This diagnostic method precludes the need for radioisotopes, electrophoresis, and multiple high-stringency reaction conditions. The multiplicity of mutant globin genes present in Southeast Asians complicates clinical diagnosis and underscores the importance of DNA-based diagnostic methods. We have applied CCA to distinguish beta A and beta E alleles. Competing 15mer primers were a fluorescein-labeled complement to beta A and a rhodamine-labeled complement to beta E, identical except for their central nucleotides. A common unlabeled primer was used to amplify DNA product, the color of which was determined by the perfectly complementary primer. Color photography and spectrofluorometry, as well as a method of black-white photography that we developed to distinguish fluorescein- and rhodamine-labeled DNA, were used to record results. We applied CCA to define the complex genotype of a Thai woman with thalassemia intermedia, 96% HbE, and 4% HbF whose possible genotypes included several permutations of alpha-thalassemia, beta-thalassemia, and beta E genes. zeta-Globin gene mapping of DNA doubly digested with Bg/II and Asp 718 showed the -alpha 3.7/--SEA genotype, and CCA confirmed homozygous beta E/beta E. The CCA is useful for diagnosing the compound hemoglobin genotypes of Southeast Asians and could be applied also to prenatal diagnosis in this population.

Adult↗
PubMed1978

The program of Friend cell erythroid differentiation: early changes in Na+/K+ ATPase function.

Treatment of Friend erythroleukemia cells with several different chemical agents causes an early decrease in the 86Rb+ influx mediated by Na+/K+ adenosine triphosphatase (ATPase). These agents, which induce Friend cells to differentiate, include dimethylsulfoxide (DMSO), ouabain, hypoxanthine, and actinomycin D. The magnitude of the early decrease in 86Rb+ influx correlates with the proportion of cells in cultures of inducible Friend cell clones which later go on to synthesize hemoglobin. Compounds which do not incude differentiation in these cells, such as xanthine, exogenous hematin, and erythropoietin, do not cause a change in 86Rb+ influx. A change in the intracellular K+ ion concentration does not occur during induction by DMSO because, although there is a decrease in K+ content per cell soon after induction, there is a parallel decrease in cell volume. These results and previous observations from this laboratory are discussed in terms of the posible involvement of the Na+/K+ ATPase in Friend cell differentiation.

Animals↗
PubMed2002

Identification of an iron-regulated, hemin-binding outer membrane protein in Sinorhizobium meliloti.

Rhizobia are soil bacteria that are able to establish symbiotic associations with leguminous hosts. In iron-limited environments these bacteria can use iron present in heme or heme compounds (hemoglobin, leghemoglobin). Here we report the presence in Sinorhizobium meliloti of an iron-regulated outer membrane protein that is able to bind hemin but not hemoglobin. Protein assignment was done by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Tryptic peptides correlated with the mass measurements obtained accounted for 54% of the translated sequence of a putative heme receptor gene present in the chromosome of S. meliloti 1021. The results which we obtained suggest that this protein (designated ShmR for Sinorhizobium heme receptor) is involved in high-affinity heme-mediated iron transport.

Amino Acid Sequence↗
PubMed1993

Compound heterozygosity for hemoglobin C and Korle-Bu: moderate microcytic hemolytic anemia and acceleration of crystal formation [corrected].

We report here that compound heterozygosity for hemoglobin Korle-Bu (HbKB) and HbC (beta 6 Glu-->Lys) is associated with moderate chronic hemolytic anemia with microcytosis. To understand the pathogenesis of this syndrome, we have studied the effect of Hb Korle-Bu (KB = beta 73 Asp-->Asn) on the crystallization of HbC. We have previously established that fetal Hb (HbF) inhibits the crystallization of HbC. In contrast, HbS accelerates crystallization affecting the pathogenesis of SC disease. We now report on in vitro crystallization of mixtures of HbKB, HbC, and various amounts of HbF and the native hemolysate of a child who is a compound heterozygote for HbKB and HbC. At 6 months of age, the propositus' hemolysate contained 55% HbKB, 39% HbC, and 6% HbF. Crystal formed within 2 minutes compared with 30 minutes for the mixture of 40% HbC:60% HbS and with 180 minutes for 40% HbC:60% HbA. The morphology of the crystals formed was cubic, in contrast with the tetragonal crystals observed in CC and SC disease. Early crystals did not exhibit "sharp edges" until 45 minutes. Purified HbKB formed aggregates but not crystals after 24 hours. Isopycnic gradients showed that the KB/C compound heterozygotes have red blood cell (RBC) densities intermediate between the AC and CC phenotype and similar to SC disease. The surface residue beta 73, known to participate in areas of interaction of the deoxy HbS polymer, can now be assigned to areas of contact in HbC containing crystals. The hemolysis observed in the HbKB/C compound heterozygote is likely to be secondary to the acceleration of Hb crystallization. The microcytosis and increased RBC density is clearly the consequence of the presence of HbC, but the basis of the increased RBC pathology compared with AC trait, despite the low proportion of HbC (35% to 40%), remains to be elucidated.

Adolescent↗
PubMed1986

The intermediate compounds between human hemoglobin and carbon monoxide at equilibrium and during approach to equilibrium.

The procedure of Perrella et al. (Perrella, M., Benazzi, L., Cremonesi, L., Vesely, S., Viggiano, G., and Rossi-Bernardi, L. (1983) J. Biol. Chem. 258, 4511-4517) for trapping the intermediate compounds between human hemoglobin and carbon monoxide was validated by quantitatively determining during the approach to equilibrium all the species present in a solution containing large amounts of intermediates. An accurate estimate of the intermediate compounds at 50% carbon monoxide saturation in 0.1 M KCl, pH 7, at 22 degrees C, allowed the calculation, according to Adair's scheme, of the four equilibrium constants. At 50% ligand saturation, the pool of intermediate species was about 12% of the total. A slightly greater concentration of tri-liganded than mono-liganded species was found. Carbon monoxide bound to beta chains in slightly greater excess with respect to alpha chains in both the mono- and tri-liganded species. The symmetrical bi-liganded intermediates, alpha 2 beta CO2 and alpha 2CO beta 2, were absent. The nature of the bi-liganded intermediate found to be present in detectable amounts by our technique has yet to be clarified: it could be either the asymmetrical species (alpha beta) (alpha CO beta CO) and (alpha beta CO) (alpha CO beta) or both of them. Such a finding on the functional heterogeneity among the four possible bi-liganded intermediates is consistent with hypotheses of the existence of more than two quaternary structures in the course of ligand binding to hemoglobin.

Carbon Monoxide↗
PubMed1989

Comparison of in vivo binding of aromatic nitro and amino compounds to rat hemoglobin.

The hemoglobin (Hb) binding of five nitroarenes, i.e. nitrobenzene (NB), 4-nitrobiphenyl (4-NBP), 1-nitropyrene (1-NP), 2-nitronaphthalene (2-NN) and 2-nitrofluorene (2-NF), and the corresponding amines, administered p.o. to male S.D. rats, was determined by HPLC, to evaluate the extent of in vivo reductive and oxidative activations of these compounds to N-hydroxylamines, which covalently bind to Hb to form acid-labile sulfinamides. Hb binding of the nitroarenes, except for NB, was significantly lower than that of the corresponding amines. Among the aromatic amines, 4-aminobiphenyl exhibited extremely high Hb binding. Hb binding of NB and 4-NBP decreased markedly after pretreatment with a mixture of antibiotics, but the binding of the others did not decrease appreciably. 1-Aminopyrene and 1-NP bound abundantly to plasma proteins, although the Hb binding was slight. Based on the Hb binding and the in vitro metabolism by liver microsomes and intestinal bacteria, the extent of in vivo reductive activation of nitroarenes is discussed.

Amines↗
PubMed1995

Fetal hemoglobin expression in compound heterozygotes for -117 (G-->A)A gamma HPFH and beta zero 39 nonsense thalassemia.

The -117(G-->A)A gamma hereditary persistence of fetal hemoglobin (Greek HPFH) and beta zero 39-thal mutations are rather frequent in Sardinia so that their interaction is to be expected. Characterization of eight compound heterozygotes for these defects indicated that HPFH was linked to haplotype VII and beta zero 39-thal to haplotype II. Haplotype II beta zero 39-thal chromosome carries the A gamma T gene which is a useful marker of gamma-gene expression. Since the Hb F level in these compound heterozygotes was significantly higher than in 46 -117 HPFH carriers, the A gamma I, A gamma T, and G gamma globin level was determined. A gamma T was underexpressed while G gamma was significantly increased, which suggest that in -117 A gamma HPFH/beta zero 39-thal healthy subjects the increase in Hb F production is determined only by the -117 mutated A gamma gene and the adjacent G gamma gene.

Adult↗
PubMedDate not supplied

Compound heterozygosity for hemoglobin Knossos [alpha 2 beta 2 27 (B9) Ala-Ser] and IVS I-1 mutation.

A three-year-old female with compound heterozygosity for Hb Knossos and IVS-I-1 mutation is presented. On physical examination she had no abnormality except for pallor. Hb was 6.9 g/dl, MCV 61 fl, Hb A2 2% and Hb F 38.5%. Acrylamidegel electrophoresis at a pH of 6 revealed the presence of Hb Knossos in the child and her father. DNA studies revealed that the child was compound heterozygous for Hb Knossos and the IVS I-1 mutation. When the clinical expression of this combination in a previously reported patient with Hb Knossos/FSC8 mutation is compared, it is shown that the newly presented patient has a more severe condition, indicating that the mutations in the trans of Hb Knossos may play a role in the phenotypical expression of the disease.

Anemia↗
PubMed1979

Resonance Raman and EPR of nitrosyl human hemoglobin and chains, carp hemoglobin, and model compounds. Implications for the nitrosyl heme coordination state.

We report the joint resonance Raman (RR) and electron paramagnetic resonance (epr) study of five- and six-coordinate nitrosyl heme model compounds and of the titled nitrosyl hemoproteins. Both epr and RR spectra fall into two types which, in the models, correspond to five- and six-coordinate nitrosyl hemes. However, neither RR nor epr spectroscopy is highly sensitive to the nature of the bond between a nitrosyl heme and a coordinated nitrogenous base, nor do the results of one technique uniformly correlate with those of the other. It is not possible to use epr spectroscopy as a test for the coordination state of a nitrosyl heme. The position of the highest frequency (depolarized) RR band possibly provides such a test. Any breaking of the very weak bond between nitrosyl heme and proximal histidine in T state human HbNO is more a consequence of tertiary structural features unique to the human alphaNO chains than it is of properties of the T quaternary conformation.

Animals↗
PubMed1978

"Tension" on heme by the proximal base and ligand reactivity: conclusions drawn from model compounds for the reaction of hemoglobin.

The kinetic data on model compounds of hemoglobin indicate that in oxyderivatives ligand dissociation rates are sensitive to the "tension" exerted by the proximal base on the metal-to-ligand bond; the corresponding rates for carboxy derivatives are not sensitive to the tension. It is suggested that the metal-to-ligand bond becomes weaker with increased "pull" (or tension) on Fe from the proximal base due to the steric and/or electronic interaction between the ligand, the porphyrin ring, and the proximal base. In model compounds the linear heme Fe-to-CO bound vis-a-vis the bent heme Fe-to-O2 bond probably makes such interactions less significant in carboxy derivatives. It is proposed that the kinetic alpha,beta-chain nonequivalence in Hb4(O2)4 is due to the difference in the tension in the two chains on Fe by the proximal base. The absence of alpha,beta-chain differences large enough to show up in CO dissociation rates from Hb4(CO)4 is explained on the basis of lack of sensitivity of the Fe-CO bound to tension from the proximal base. The implications of the results for the observed cooperative effects in ligand combination (for CO) and dissociation (for O2 and NO) rates of hemoglobin have also been discussed.

Carbon Monoxide↗