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Biomedical subjects

H F Bunn

Publications and source records attributed to H F Bunn.

At least 163 records · Page 9Linked to original sources
PubMed1973

The effect of aspirin on sickling and oxygen affinity of erythrocytes.

The recent suggestion that the administration of aspirin might be useful in the treatment of sickle-cell anemia has been further studied and found to be without basis. After incubation with aspirin, sickle-cell erythrocytes are not inhibited from sickling after deoxygenation. In addition, although aspirin does transfer the acetyl group to hemoglobin both in vitro and in vivo, in our experiments the reaction does not result in any alteration in the oxygen equilibrium of either intact erythrocytes or hemoglobin in solution. Furthermore, patients maintained on long-term aspirin administration also showed no shift in the oxygen affinity of their blood.

Anemia, Sickle Cell↗
PubMed1973

Hemoglobin brigham (alpha2Abeta2100 Pro--Leu). Hemoglobin variant associated with familial erythrocytosis.

Erythrocytosis associated with the presence of a hemoglobin with increased oxygen affinity has been reported for 10 hemoglobin variants, most of which demonstrate altered electrophoretic mobility. Several members of a family were found to have erythrocytosis, and both the whole blood and the hemoglobin exhibited increased oxygen affinity. Phosphate-free hemoglobin solutions had a normal Bohr effect and reactivity to 2,3-diphosphoglycerate. The electrophoretic properties of the hemoglobin were normal, but on peptide mapping of a tryptic digest of the isolated beta-chains, a normal betaT11 peptide and an abnormal betaT11 with greater R(f) were seen. Analysis of the abnormal peptide showed the substitution of leucine for the normal proline at beta100 (helical residue G2).The hemoglobin variant, designated Hb Brigham, serves to emphasize the necessity for detailed evaluation of the structure and function of hemoglobin in familial erythrocytosis even with electrophoretically "normal" hemoglobin.

Amino Acids↗
PubMed1973

Effects of cyanate and 2,3-diphosphoglycerate on sickling. Relationship to oxygenation.

Cyanate and 2,3-diphosphoglycerate (2,3-DPG) both influence the oxygen affinity of hemoglobin. The studies presented here concern the effects of these compounds on the sickling phenomenon. The inhibitory effect of cyanate on sickling is largely due to the fact that it increases the percentage of oxyhemoglobin S at a given oxygen tension. In addition, cyanate inhibits sickling by a mechanism that is independent of oxygenation. In this paper, we have demonstrated that the viscosity of carbamylated sickle blood was lower than that of non-carbamylated controls at the same oxygen saturation. Furthermore, carbamylation resulted in an increase in the minimum concentration of deoxy-sickle hemoglobin required for gelation. Like cyanate, 2,3-DPG affected sickling of intact erythrocytes by two mechanisms. Since 2,3-DPG decreases the percentage of oxyhemoglobin S at a given oxygen tension, sickling is enhanced. In addition, 2,3-DPG had a direct effect. When the intracellular 2,3-DPG concentration was increased in vitro, a greater percentage of cells were sickled at a given oxygen saturation. Conversely, sickling was inhibited in cells in which 2,3-DPG was artificially lowered. These data indicate that the enhancement of sickling by 2,3-DPG is in part independent of its influence on oxygen affinity.

Anemia, Sickle Cell↗
PubMed1972

Structural and functional studies on hemoglobin Bethesda (alpha2beta2 145His), a varient associated with compensatory erythrocytosis.

Studies have been performed on a 12-yr-old Chinese girl with compensatory erythrocytosis due to the presence of hemoglobin Bethesda comprising about 45% of the red cell hemoglobin. Her parents and three siblings were normal. The oxygen affinity of her blood was markedly increased: under physiological conditions (pH 7.40, 37 degrees C). P(50) was 12.8 mm Hg (normal = 26.5 mm Hg). The red cell 2,3-diphosphoglycerate (2.3-DPG) level was normal. The abnormal hemoglobin could not be separated from hemoglobin A by zone electrophoresis at pH 8.6 or isoelectric focusing on polyacrylamide gel. However, after the hemoglobin was split into free alpha and beta chains by treatment with p-hydroxymercuribenzoate (PMB) or 6 M urea, an abnormal beta chain was readily demonstrated having a higher isoelectric point (more positive net charge) than normal beta(A). Structural analysis of the variant beta chain demonstrated the substitution of histidine for tyrosine at position 145: hemoglobin Bethesda (alpha(2)beta(2) (145His)). From earlier chemical and crystallographic studies, it has been postulated that this residue is a critical determinant of hemoglobin function. Hemoglobin Bethesda was separated from hemoglobin A by column chromatography. Oxygen equilibria of purified hemoglobin Bethesda revealed an extremely high oxygen affinity (exceeding that of isolated alpha and beta chains), and markedly reduced cooperativity. The Bohr effect of hemoglobin Bethesda was 1/3 that of hemoglobin A. However, hemoglobin Bethesda showed a significant interaction with 2.3-DPG and inositol hexaphosphate.

Adenosine Triphosphate↗
PubMed1972

Oxygen equilibrium of hemoglobin E.

Oxygen equilibrium was determined on hemoglobin of individuals both heterozygous and homozygous for hemoglobin E. The whole blood oxyhemoglobin dissociation curve of AE blood was identical to that of normal AA blood. E hemoglobin, isolated by diethylaminoethyl Sephadex and carboxymethyl cellulose column chromatography, had oxygen affinity, heme-heme interaction, and Bohr effect identical to those of hemoglobin A prepared from the same column. Furthermore, the two hemoglobins had equal reactivity with 2,3-diphosphoglycerate. Phosphate-free hemolysates of blood from E and A homozygotes also had identical oxygen saturation curves. These results do not confirm earlier reports that hemoglobin E has an abnormally low oxygen affinity.

Adult↗