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PubMed1982

Effect of liganded hemoglobin S and hemoglobin A on the aggregation of deoxy-hemoglobin S.

The effect of the carbonmonoxy forms of Hb S and Hb A on the solubility and kinetics of the aggregation of deoxy-Hb S in concentrated phosphate buffer was studied. The delay time was prolonged exponentially when the ratios of CO-Hb S and CO-Hb A to deoxy-Hb S were increased. This increase in the delay time prior to aggregation can be explained by the decrease in the concentration of deoxy-Hb S. As with deoxy-Hb A, the n value for the delay time prior to the aggregation of deoxy Hb S was unaffected by CO-Hb S and CO-Hb A. Electrophoretic and spectrophotometric analyses of the composition of CO- and deoxy-Hbs A and S in the solution before and after aggregation showed that CO-Hb S co-polymerized with deoxy-Hb S but that CO-Hb A did not. The amount of CO-Hb S in the polymer phase depended on the initial fraction of the CO form of Hb S. The participation of CO-Hb S in the polymer phase was further confirmed by direct measurement of the absorption spectra of the polymer phase after it was dissolved in deoxygenated phosphate buffer. From these results, we concluded that nuclei are formed only from deoxy-Hb S, but that once nuclei are formed, CO-Hb S and deoxy-Hb A co-polymerize with deoxy-Hb S.

Carbon Monoxide↗
PubMed1991

Hemoglobin aggregation and pseudosickling in vitro of hemoglobin Setif-containing erythrocytes.

Erythrocytes from individuals heterozygous for hemoglobin Setif (alpha 94 Asp----Tyr) sickle in vitro without deoxygenation when incubated in chloride buffer due to hemoglobin aggregation. We now report quantitative studies of hemoglobin polymerization and deformability in these cells. Hemoglobin polymer gradually increased in intact cells during a 24 h incubation period at 24 degrees C. After 24 hr, about 80% of the cells in 290 mOsm sodium chloride buffer contained polymer which appeared as short rods compared to greater than 99% containing polymer at 450 mOsm. Similar proportions of cells were morphologically sickled. Deformability of erythrocytes with 40% hemoglobin Setif incubated in 290 mOsm buffer at 37 degrees C decreased to 80% of normal by 210 min but in 450 mOsm decreased to 50% after only 30 min as measured by the ektacytometer. However, at 4 degrees C deformability remained normal even in 450 mOsm buffer. The solubility of gelled hemolysate containing 40% hemoglobin Setif was 24 g/dl and 21 g/dl at 290 and 459 mOsm buffer respectively. The gel persisted at 4 degrees C with a solubility of 26 g/dl, but melted when dialyzed into sodium phosphate or potassium phosphate buffer. These data suggest that hemoglobin polymerization, reduced deformability, and sickling of hemoglobin Setif-containing erythrocytes are related to reduced hemoglobin solubility. The rate and extent of intracellular polymerization in vitro are considerably reduced (as in the case of sickle trait) compared with erythrocytes from individuals with sickle cell anemia. Hence, the slower kinetics of hemoglobin aggregation in hemoglobin Setif-containing cells provide an alternate system for studying hemoglobin polymerization and abnormal rheology.

Anemia, Sickle Cell↗
PubMed1976

Copper and the oxidation of hemoglobin: a comparison of horse and human hemoglobins.

Oxidation studies of hemoglobin by Cu(II) indicate that for horse hemoglobin, up to a Cu(II)/heme molar ratio of 0.5, all of the Cu(II) added is used to rapidly oxidize the heme. On the other hand, most of the Cu(II) added to human hemoglobin at low Cu(II)/heme molar ratios is unable to oxidize the heme. Only at Cu(II)/heme molar ratios greater than 0.5 does the amount of oxidation per added Cu(II) approach that of horse hemoglobin. At the same time, binding studies indicate that human hemoglobin has an additional binding site involving one copper for every two hemes, which has a higher copper affinity than the single horse hemoglobin binding site. The Cu(II) oxidation of human hemoglobin is explained utilizing this additional binding site by a mechanism where a transfer of electrons cannot occur between the heme and the Cu(II) bound to the high affinity human binding site. The electron transfer must involve the Cu(II) bound to the lower affinity human hemoglobin binding site, which is similar to the only horse hemoglobin site. The involvement of beta-2 histidine in the binding of this additional copper is indicated by a comparison of the amino acid sequences of various hemoglobins which possess the additional site, with the amino acid sequences of hemoglobins which do not possess the additional site. Zn(II), Hg(II), and N-ethylmaleimide (NEM) are found to decrease the Cu(II) oxidation of hemoglobin. The sulfhydryl reagents, Hg(II) and NEM, produce a very dramatic decrease in the rate of oxidation, which can only be explained by an effect on the rate for the actual transfer of electrons between the Cu(II) and the Fe(II). The effect of Zn(II) is much smaller and can, for the most part, be explained by the increased oxygen affinity, which affects the ligand dissociation process that must precede the electron transfer process.

Animals↗
PubMed2003

Hemoglobin predicts long-term survival in dialysis patients: a 15-year single-center longitudinal study and a correlation trend between prealbumin and hemoglobin.

BACKGROUND: Dialysis patients have much higher mortality rates than the general population. Anemia is a common complication of uremia and a major contributor to morbidity and mortality in dialysis patients. The benefits of anemia correction using recombinant human erythropoietin (rHuEPO) are well established. Optimum hemoglobin level for dialysis patients remain controversial. We have investigated the association of enrollment hemoglobin with long-term survival in hemodialysis (HD) and peritoneal dialysis (PD) patients. METHODS: We enrolled 529 HD and 326 PD patients from 1987 and followed them to April 2003. Demographics, enrollment, and clinical and laboratory data were recorded. The Kaplan-Meier method was used to compute observed survival, and the multivariate Cox regression analysis was used to identify the independent predictors of mortality risk. RESULTS: Mean ages of HD and PD patients were 60 +/- 16 (SD) and 54 +/- 16 (SD) years, respectively. Forty-seven percent of HD patients and 41% of PD patients were diabetic. Mean enrollment hemoglobin levels of HD and PD patients were 9.44 +/- 1.9 and 9.61 +/- 1.77 g/dL respectively. Cumulative 15 year observed survivals of HD (P = 0.05) and PD (P = 0.032) patients with hemoglobin levels greater or equal to 12 g/dL were higher than those with hemoglobin levels less than 12 g/dL. Hemoglobin <12 g/dL was a better predictor of mortality in nondiabetics than diabetics, particularly in HD patients. Both in HD and PD diabetic patients, hemoglobin was not a significant predictor of mortality. By Cox regression analysis, after adjusting for age, race, gender, and months on dialysis at enrollment, the relative risk of mortality of patients with hemoglobin <12 g/dL was 2.13-fold (P = 0.008) higher for HD and 1.85-fold (P = 0.06) higher for PD compared to those with hemoglobin >/=12 g/dL (P = 0.035). A logistic regression analysis revealed a strong inverse relationship between the hemoglobin level and the odds risk of death in HD (OR = 0.83, P = 0.008) and in PD (OR = 0.85, P = 0.02) patients. CONCLUSION: Enrollment hemoglobin is a predictor of long-term survival in HD and PD patients. Patients with hemoglobin levels that are higher than current treatment recommendations (>12 g/dL) may benefit from long-term survival. Survival of dialysis patients may be improved by better management of malnutrition and anemia.

Adult↗
PubMed1978

Net charge and oxygen affinity of human hemoglobin are independent of hemoglobin concentration.

The dependence of net charge and oxygen affinity of human hemoglobin upon hemoglobin concentration was reinvestigated. In contrast to earlier reports from various laboratories, both functional properties of hemoglobin were found to be independent of hemoglobin concentration. Two findings indicate a concentration-independent net charge of carbonmonoxy hemoglobin at pH 6.6: (A) The pH value of a given carbonmonoty hemoglobin solution remains constant at 6.6 when the hemoglobin concentration is raised from 10 to 40 g/dl, indicating that there is no change in protonation of titratable groups of hemoglobin: (b) the net charge of carbonmonoxy hemoglobin as estimated from the Donnan distribution of 22Na+ shows no dependence on hemoglobin concentration in this concentration range. The oxygen affinity of human hemoglobin was determined from measurements of oxygen concentrations in equilibrated samples using a Lex-O2-Con apparatus (Lexington Instruments, Waltham, Mass.). P50 averaged 11.4 mm Hg at 37 degrees C, pH = 7.2, and ionic strength approximately 0.15. Neither P50 nor Hill's n showed any variation with hemoglobin concentrations increasing from 10 to 40 g/dl.

Electrophysiology↗
PubMed1998

hgpB, a gene encoding a second Haemophilus influenzae hemoglobin- and hemoglobin-haptoglobin-binding protein.

Haemophilus influenzae requires heme for growth and can utilize both hemoglobin and hemoglobin-haptoglobin as heme sources. We previously identified a hemoglobin- and hemoglobin-haptoglobin-binding protein, HgpA, in H. influenzae HI689. Mutation of hgpA did not affect binding or utilization of either heme source. The hgpA mutant exhibited loss of a 120-kDa protein and increased expression of a 115-kDa protein. These data suggested that at least one other gene product is involved in binding of these heme sources by H. influenzae. A 3.2-kbp PCR product derived from HI689 was cloned. The nucleotide sequence indicated a separate, distinct gene with high homology to hgpA, which would encode a 115-kDa protein. Primers were designed for directional cloning of the structural gene in the correct reading frame. Sonicates of induced Escherichia coli harboring the cloned open reading frame bound both hemoglobin and hemoglobin-haptoglobin. An insertion/deletion mutant of H. influenzae at the newly identified locus, designated hgpB, was constructed. The 115-kDa protein was not detected in the mutant after affinity purification using biotinylated hemoglobin. An hgpA hgpB double-mutant strain exhibited a reduced ability to utilize hemoglobin-haptoglobin, although it was unaltered in the ability to utilize hemoglobin. Affinity isolation of hemoglobin-binding proteins from the double mutant resulted in isolation of an approximately 120-kDa protein. Internal peptide sequencing revealed this protein to be a third distinct protein, highly homologous to HgpA and HgpB. In summary a second hemoglobin- and hemoglobin-haptoglobin-binding protein of H. influenzae has been identified and characterized, and the presence of an additional protein of similar function has been revealed.

Amino Acid Sequence↗
PubMed1975

The inhibition of the primary interaction between 125I-labeled human hemoglobin and rabbit anti-human hemoglobin sera: a sensitive radioimmunoassay technique.

A rapid and sensitive radioimmunoassay technique for hemoglobin based upon a modification of the Farr test is described. Since hemoglobin is soluble in ammonium sulfate whereas antibody is precipitated, the amount of free and antibody-bound radiolabeled human hemoglobin can be quantitatively measured after ammonium sulfate precipitation. Nanogram quantities of hemoglobin can be detected by the addition of unlabelled human hemoglobin to the antiserum before the labeled hemoglobin, thus establishing a competition reaction between labeled and unlabeled antigen for antibody. If sufficient quantities of unlabeled human hemoglobin are present, all of the antibody combining sites become saturated and the primary interaction between 125-I-labeled hemoglobin and antibody is completely inhibited. The method can be employed to discriminate various normal human hemoglobins, non-human primate hemoglobins as well as sickle-cell hemoglobin (HbS). Other possible applications of the technique are discussed.

Ammonium Sulfate↗
PubMed1982

Studies on reconstituted myoglobins and hemoglobins. II. Role of the heme side chains in the oxygenation of hemoglobin.

To clarify the functional role of the 2- and 4-side chains of heme in hemoglobin we prepared several hemins carrying nonnatural side chains at positions 2 and 4, reconstituted human adult hemoglobins with them, and investigated their optical and oxygen binding properties. The absorption maxima for all these reconstituted hemoglobins, no matter whether they are oxy-, deoxy-, or carbon monoxy-form, shifted toward shorter wavelengths than those for protoheme-hemoglobin. As in the case of myoglobin (Kawabe, K., et al. (1982) J. Biochem. 92, 1703-1712), the absorption spectrum is more significantly affected by resonance effects than by the inductive effects of the peripheral heme substituents. Contrary to the case of myoglobins, the spectral difference between pemptoheme-hemoglobin and isopemptoheme-hemoglobin and that between 2-isopropyl-4-vinyl-deuteroheme-hemoglobin and 2-vinyl-4-isopropyldeuteroheme-hemoglobin were very small. All the reconstituted hemoglobins used in this study showed higher oxygen affinity and reduced cooperativity in oxygen binding than native hemoglobin. We have shown that the 2- and 4-side chains are functionally nonequivalent and that modification of the 4-side chain exerts greater influence on oxygen affinity than modifying the 2-side chain. The magnitude of the Bohr effect and response to 2,3-diphosphoglycerate and inositol hexaphosphate were reduced in the reconstituted hemoglobins. We have proposed a stereochemical mechanism based on constraint of heme movement before ligation against the tight distal side of the heme pocket.

Animals↗
PubMed1983

Mechanisms of the adjuvant effect of hemoglobin in experimental peritonitis. VI. Effects of stroma-free hemoglobin and red blood cell stroma on mortality and neutrophil function.

Hemoglobin is known to increase the lethality of experimental E. coli peritonitis, but its mechanism of action has not been defined. Some evidence from this laboratory previously suggested that hemoglobin could interfere with local leukocyte function in the peritoneal cavity. In the present study we compared the effect of impure bovine hemoglobin, highly purified stroma-free hemoglobin, and red blood cell stroma on the mortality rate of rats with Escherichia coli peritonitis, as well as on human neutrophil function in vitro. Both hemoglobin preparations markedly increased the mortality rate at low bacterial concentrations. Red blood cell stromal elements increased the rate to a minimal degree and only at high bacterial concentrations. The character of the E. coli-induced peritoneal leukocytosis was not significantly affected by concomitant administration of either stroma-free hemoglobin or red blood cell stroma. Although crystalline bovine hemoglobin inhibited in vitro leukocyte chemotaxis, centrifugation of this preparation to remove debris abrogated this effect. Stroma-free hemoglobin had no effect on in vitro leukocyte chemotaxis. Red blood cell stromal elements in high concentration diminished phagocytosis and bacterial killing by human neutrophils, but stroma-free hemoglobin had no effect on these neutrophil functions. The results confirm that hemoglobin is a potent adjuvant in experimental E. coli peritonitis, but contrary to our previous conclusion does not owe this effect to direct interference either with neutrophil influx into the peritoneal cavity during bacterial peritonitis or with human leukocyte function in vitro. Such prior conclusions appear to have been based on insoluble material including stromal elements in the hemoglobin preparations used. Red cell stromal elements derived from as little as 1 ml of packed red cells can significantly interfere with the phagocytosis and killing of E. coli.

Animals↗
PubMed1984

Mechanism of the adjuvant effect of hemoglobin in experimental peritonitis: VIII. A leukotoxin is produced by Escherichia coli metabolism in hemoglobin.

Hemoglobin, but not albumin, has long been recognized as an infection potentiating factor in experimental Escherichia coli peritonitis, but the mechanism has defied definition. We have shown previously that stroma-free hemoglobin is not toxic to polymorphonuclear neutrophils. To test the hypothesis that hemoglobin provides a nutritional boost to the growth of E. coli in vivo, we inoculated E. coli into dialysis bags containing equivalent amounts of stroma-free hemoglobin or albumin. These bags were implanted into the peritoneal cavity of rats and at intervals the fluid was removed and the bacteria enumerated. This technique allows for intraperitoneal bacterial growth but eliminates the variables of lymphatic clearance and phagocytic ingestion. The growth rate of E. coli was the same irrespective of the nutritional supplement in the bag. Thus there is no experimental support for the notion that hemoglobin directly accelerates E. coli proliferation under in vivo conditions. To test the hypothesis that a leukocyte toxin may result from E. coli growth in hemoglobin, we exposed normal human neutrophils to the sterilized contents of the peritoneal dialysis bags. In vitro function of the neutrophils (viability, random migration, chemotaxis, phagocytosis, bacterial killing, and chemiluminescence) was significantly depressed by prior exposure to hemoglobin supernatants that had supported E. coli proliferation in vivo. Stroma-free hemoglobin had minimal adverse effects. Albumin supernatants that had supported E. coli proliferation in vivo had significantly less effect on neutrophil function even though the endotoxin levels were identical to the hemoglobin E. coli solutions. We must conclude that leukotoxins result from E. coli growth in solutions of pure hemoglobin. The data support the idea that the infection potentiating effect of hemoglobin in vivo is due to such leukotoxins.

Animals↗
PubMed1978

Specific antibodies to hemoglobin A1 (anti-Glu) and hemoglobin S (anti-Val) in the guinea pig: immunologic and structural correlations.

Like goats and sheep, guinea pigs can produce, in response to human sickle cell hemoglobin (beta6 Glu leads to Val), an antibody population (anti-Val) that will bind sickle cell hemoglobin but not normal hemoglobin HbA. Unlike goats and sheep, guinea pigs can produce in response to human hemoglobin A1 an antibody fraction, anti-Glu, that will not react with human sickle cell hemoglobin. These anti-Glu antibodies have been isolated by affinity chromatography and their specificity confirmed by fluorescence-quenching titrations. The sequence of the first 10 amino acids of the beta-chain of guinea pig hemoglobin has been determined. This sequence differs from those of both hemoglobin HbA and sickle cell hemoglobin by two residues, those at positions 5 and 6. This explains the similarity of the immunogenicity of this site on the two human hemoglobins when administered to guinea pigs. Both goats and sheep are identical to hemoglobin A1 at the beta-6 position.

Amino Acids↗
PubMed1998

Comparison of hemoglobin A1C results by two different methods on patients with structural hemoglobin variants.

OBJECTIVES: The objective was to compare hemoglobin A1C (HbA1C) results obtained by two methods based on different analytical principles for individuals with a structural hemoglobin variant. DESIGN AND METHODS: Hemoglobin A1C results were obtained using the Bio-Rad Variant (based on cation exchange chromatography) and the Bayer DCA 2000 (based on an immunological reaction) on individuals with a structural hemoglobin variant. The identity of the hemoglobin variant was confirmed by high pressure liquid chromatography (HPLC) and electrophoresis. RESULTS: Hemoglobin A1C results obtained by the two methods on individuals with S, C, D, and E trait were in close agreement. CONCLUSION: The Bio-Rad Variant and Bayer DCA 2000 produce equivalent hemoglobin A1C results on patients with S, C, and E trait. With appropriate correction, correlation of hemoglobin A1C results from the Bio-Rad Variant for individuals with D trait was good (r = 0.927). Glycohemoglobin results obtained by the two methods for some unusual structural hemoglobin variants were in close agreement.

Chromatography, Ion Exchange↗