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Biomedical subjects

E C Abraham

Publications and source records attributed to E C Abraham.

At least 73 records · Page 4Linked to original sources
PubMed1984

Glycosylated hemoglobins in heterozygotes and homozygotes for hemoglobin C with or without diabetes.

Glycosylated hemoglobin in red blood cell hemolysates of five patients homozygous for CC, 18 patients with SC condition, and 13 patients heterozygous for Hb C with or without insulin-dependent diabetes mellitus were separated by Bio-Rex 70 chromatography. The various glycosylated components were identified by analysis of the hemoglobin components for ketoamine and phosphate, in vitro glycosylation studies, and by the quantitative differences in the minor components between the participants with and without diabetes. The percentages of Hb A1a + b, Hb A1c, and Hb C1c were significantly increased in the Hb C heterozygote with diabetes. Similarly, the percentages of Hb S1a + b and Hb S1c were elevated in the SC patient with diabetes. It was noteworthy that the levels of these components became normal after adequate control of diabetes. Moreover, the levels of Hb C1c in the CC participants and Hb S1c (Hb S1c/total Hb S) in the SC patients were significantly higher than the Hb S1c levels previously reported in patients with sickle cell anemia. These findings might reflect the fact that CC and SC patients have less severe hemolytic anemia. Moreover, the relative proportions of Hb A1c and Hb C1c were nearly the same in Hb C heterozygotes, which indicated that Hb A and Hb C were glycosylated in vivo to approximately the same extent.

Anemia, Sickle Cell↗
PubMed1983

Demonstration of a minor hemoglobin with modified alpha chains and additional modified hemoglobins in normal and diabetic adults.

We have attempted to separate various hemoglobins in 10 normal and 11 diabetic persons by Bio-Rex 70 chromatography at 4 degrees C with an exponentially increasing sodium phosphate gradient. Minor hemoglobins, namely AIa1, AIa2, AIb1, AIb2, AIb3, AIc, AId1, AId2 and AId3, have been separated and eluted in that order. Most of these minor hemoglobins were newly observed and could not be detected by the previous chromatographic techniques. On the basis of colorimetric assay protein-bound ketoamine was present in all the minor hemoglobins, which was confirmed by chromatographic separation of hemoglobins after reduction with NaB3H4. All the minor hemoglobins, with the exception of Hb AIa1, HbIa2, and Hb AIb1, showed a 2-fold increase in the diabetic patients. Hb AIc (5.0% in normals; 9.0% in diabetics) and Hb AId3 (1.9% in normals; 3.2% in diabetics) were present in the largest amounts. Both Hb AId3 and Hb Ao showed a decrease in oxygen affinity in the presence of 2,3-diphosphoglycerate, whereas Hb AIc showed no effect. Separation of globin chains by cellulose acetate electrophoresis at pH 8.6 showed that the cathodal mobility of the alpha chains of Hb AId3 was slower than those of Hb Ao. Glycosylation of Hb with [14C]glucose followed by separation of hemoglobins by two Bio-Rex 70 chromatographic methods indicated that the minor Hb formed by glycosylation of the alpha-chain amino-terminus was separated from Hb Ao, while the minor hemoglobins formed by the glycosylation of epsilon-NH2 groups chromatographed with Hb Ao.

Chromatography, Ion Exchange↗
PubMed1983

Affinity chromatographic quantitation of glycosylated hemoglobin in newborn infants.

Levels of glycosylated hemoglobin (glyco Hb) were determined in 45 newborn infants by affinity chromatography on phenylboronate-agarose gel and found to correlate well with the results obtained by two chemical methods. However the percentages of Hb FIa+b and Hb FIc determined by Bio-Rex 70 chromatography did not correlate with the glyco Hb values. The glyco Hb levels in the newborns were significantly lower than in the adults. Rechromatography of the glyco and nonglyco Hb fractions on Bio-Rex 70 columns indicated that Hb FO-like glyco Hb (presumably formed by glycosylation of the alpha chain amino terminus and epsilon-amino groups of lysyl amino acids) constituted about 60% of the glyco Hb fraction, whereas both Hb FIc and Hb FIa+b components contained only small portions of the glyco Hb.

Adult↗
PubMed1983

Changes in glycosylated hemoglobins with red cell aging in normal and diabetic subjects and in newborn infants of normal and diabetic mothers.

To determine red cell age-related changes in the formation of glycosylated (glyco) hemoglobins (Hbs), red cells were fractionated by dextran 40 density gradient centrifugation and glyco Hbs determined by both Bio-Rex 70 cation exchange and phenylboronate-agarose affinity chromatographic methods. Blood samples from a normal adult, adults with White's class A diabetes and insulin dependent diabetes mellitus (IDDM), and newborns of normal and diabetic women were used for this study. Red cell fractions from the newborns and the adults showed a steady increase in the levels of glyco Hb determined by the affinity method with increasing red cell density. In the newborns, the absolute levels and the increase of glyco Hb were smaller than in the adults, probably because of decreased red cell survival in fetuses compared to adults. The glyco Hb value for each cell fraction was significantly higher in the adult with IDDM and in the newborns of diabetic women. In the adults, the levels of Hb Ala + b and Hb Alc determined by Bio-Rex 70 chromatography also showed an increase with increasing red cell age. In the newborns, Hb Flc, which contains predominantly acetylated and some glycosylated Hb F, showed only a small increase with increasing red cell age over and above that due to a concomitant increase in Hb F. On the contrary, Hb Fla + b, which contains mostly glyco Hb F, showed a larger increase. The results confirm that glycosylation, but not acetylation, of Hb F takes place over the entire lifespan of red cells.

Adult↗
PubMed1983

Application of affinity chromatography for separation and quantitation of glycosylated hemoglobins.

The use of m-aminophenylboronic acid immobilized on agarose as the affinity matrix for the separation and quantitation of Glyco Hb has been investigated. The glyco fraction isolated from the affinity columns contained about 10% Hb A1a + b, 52% Hb A1c, and 38% Hb A0-like glyco components. The nonglyco fraction had major portions of Hb A1a + b and Hb A0 and a small amount of Hb A1c (also contained Hb F). In normals and diabetic patients, the comparison of the affinity method with the ion-exchange chromatographic, fluorometric, and colorimetric methods showed good correlation. The affinity method also showed acceptable precision and reproducibility. The presence of labile aldimine did not influence the affinity method because it seems that only the stable ketoamine was bound to the affinity gel and thus separated by this method. Moreover, this method was less sensitive to variations in column temperature and sample age. Glyco Hb levels were determined in newborn infants and in adults with various hemoglobinopathies. The results indicated that the presence of Hb F, Hb S, and Hb C did not affect the glyco Hb determinations. Thus the affinity chromatographic approach has wider application than ion-exchange chromatography and is, at the same time, much simpler and faster than the chemical methods.

Adult↗
PubMed1982

Modification of sickle hemoglobin by acetaldehyde and its effect on oxygenation, gelation and sickling.

Erythrocytes from sickle cell anemia patients and chromatographically purified Hb S0 were incubated with 0.25 to 120 mM acetaldehyde for 15 min to 6 h at different temperatures and pH. Several hemoglobin adducts stable to dialysis were separated by Biorex 70 chromatography and the proportions of the adducts formed were dependent on the period of incubation, acetaldehyde concentration, pH and temperature. Acetaldehyde treatment showed an increase in solubility, minimum gelling concentration and oxygen affinity and a decrease in sickling which showed a dependence on Hb S modification. With 0.25 to 1 mM acetaldehyde, significant inhibition of sickling was observed without any effect on the physical characteristics of the hemoglobin molecule. Acetaldehyde may act as a gelation inhibitor as well as a cell sickling inhibitor.

Acetaldehyde↗
PubMed1982

Synthesis of the minor fetal hemoglobin Fic in colonies of erythropoietic precursors isolated from human umbilical cord blood.

The biosynthesis of the minor hemoglobin FIc, which contains acetylated gamma chains, and the major hemoglobin Fo was studied during erythroid cell differentiation and maturation in cultures of erythroid precursors isolated from five human umbilical cord blood samples. A gradual decrease in the synthesis of Hb FIc was observed during the maturation of the erythroid cells when cultured from 7 to 15 days. The synthesis of Hb Fo did not show a consistent change; however, the relative synthesis of Hb FIc was the highest in the 7-day-old colonies and decreased at day 15 to levels observed in the reticulocytes. The addition of sodium butyrate, which is known to promote histone acetylation, significantly increased the synthesis of Hb FIc in 7-day-old colonies.

Butyrates↗
PubMed1982

Synthesis of hemoglobin chains in adult and newborn goats: possible influence of the beta c synthesis on the production of alpha chains.

The rates of in vitro synthesis of hemoglobin alpha and non-alpha chains were determined in adult goats during blood loss anemia and in newborn goats during postnatal development. The reticulocytes were incubated in a medium supporting protein synthesis and containing [14C] leucine. The hemoglobin chains were separated by CM-cellulose chromatography. The adult animals responded to the phlebotomy with a production of nearly 100% beta C chain about 10 days after the start of the experiment. Severe anemia and the production of beta C chain was accompanied by a significant increase in the alpha/non-alpha synthesis ratio. The gamma chain production in the newborns declined rapidly after birth and was completely replaced by that of the beta C chain in 7-10 days. No significant difference in the relative synthesis of the three types of alpha chain was observed during this period. Goats with either a homozygosity for the I alpha or I alpha B chains synthesize the I alpha (or I alpha B) and II alpha chains at a ratio of 3:1. When a heterozygosity for I alpha B chains is present the I alpha:I alpha B:II alpha ratio approximates 2:1:1. Results of kinetic studies suggest that the II alpha chains are synthesized at a slower rate than the II alpha chains. The difference in the alpha/non-alpha ratio during severe anemia may be due to a decreased production of beta C chains. No significant difference in the relative synthesis of the I alpha, I alpha B, and II alpha chains was observed between the anemic adult animal and the newborn goat or the growing kid.

Animals↗
PubMed1981

Minor fetal hemoglobins in relation to gestational age.

Cord blood samples were obtained at delivery in 44 normal women, at gestational periods ranging from 27 to 41 weeks. All women had a normal glucose screening test and 15 were delivered preterm. With the use of Biorex 70 chromatography, red cell lysates were analyzed to determine the percentages of the different hemoglobin (Hb) components, i.e., HbF1a+b, HbFlc, HbFo, and HbA. The percentage of HbFla+b in fetal blood was higher than the corresponding percentage in adult blood. The percentages and ratios of the various Hb components were compared in preterm and term fetuses and their correlation to gestational age was tested. HbF and HbF/A ratios were higher in preterm fetuses and were negatively correlated with gestational age. HbA and HbA/F ratios were lower in preterm fetuses than in term fetuses and correlated positively with gestational age. The percentages of minor components HbFla+b, and HbFlc were not significantly different in the preterm and the term fetuses, and they did not have statistically significant correlation with gestational age. However, the ratios of these minor hemoglobins to HbF, i.e., HbFla+b/HbF, and HbFlc/HbF and HbFl/HbF were found to be significantly higher in term fetuses as compared to preterm fetuses and to correlate positively with gestational age. This is probably due to the gradual lengthening of the life span of fetal erythrocytes as term approaches, which results in the erythrocytes' increased exposure to the glycolytic intermediates and possibly to glucose.

Erythrocytes↗
PubMed1981

Non-enzymatic acetylation of human hemoglobins.

Chromatographically purified Hb F0, Hb A0 and Hb S0 fractions were incubated with 70 microM [14C]acetyl-CoA for 3 h in 20 mM Tris-HCl, pH 7.6 and 8.6. The acid-precipitable radioactivity was monitored and the hemoglobins were separated by Biorex 70 chromatography. The pH dependence of acetylation showed an increase in acetylation with an increase in pH from 7.6 to 8.6, whereas an increase in ionic strength decreased acetylation. Incubation of Hb F0 with [14C]acetyl-CoA resulted in modified hemoglobin and gamma chains that co-chromatographed with Hb FIc and gamma 1c chains, respectively. Acetylation of Hb A0 and Hb S0 produced minor hemoglobins whose chromatographic mobilities were slightly faster than those of Hb AIc and Hb SIc, respectively, Radioactivity peaks also appeared at the leading edges of the major hemoglobin zones as well, which indicates that, like non-enzymatic glycosylation, non-enzymatic acetylation of hemoglobins involves both specific and nonspecific reactions.

Acetyl Coenzyme A↗
PubMed1981

Minor (glycosylated) hemoglobins in cord blood of infants of normal and diabetic mothers.

The levels of minor (glycosylated) hemoglobins in maternal blood during labor and in cord blood at delivery were determined in four groups of women: 20 normal, 22 probably normal, 20 Class A diabetic, and eight overt diabetic women. Maternal HbA, was not significantly increased in the diabetic patients, thereby reflecting adequate metabolic control. In the cord blood, the percentage of the minor hemoglobin HbF1c, which has been shown to be a mixture of acetylated glycosylated HbF, and the ratios HbF1c/HbF and HbA1/hbA were significantly increased in fetuses delivered of diabetic mothers. This supports the view that these fetuses are hyperglycemic in utero. However, there was no correlation between cord blood glycosylated hemoglobins and the birth weight ratio, a sensitive indicator of relative changes in the birth weight.

Adolescent↗
PubMed1981

Glycosylated minor components of human fetal hemoglobin. Chromatographic separation, identification, and functional characterization.

Human adult red cell lysate contains glycosylated minor hemoglobins AIa1, AIa2, AIb, and AIc. Similar minor hemoglobins, designated FIa1, FIa2, Fib, and FIc, have been separated by a Biorex 70 column chromatographic procedure from red cell lysates of newborn children and from an adult homozygote for hereditary persistence of fetal Hb. The minor Hb components were characterized by analyzing for carbohydrate and phosphate contents, by oxygen equilibrium analysis, and by comparing the chromatographic elution profiles of naturally occurring and in vitro synthesized minor components. The results indicate that Hb FIa1, Hb FIa2, and Hb FIc have been formed by the modification of gamma chains of Hb F by reacting with fructose-1,6-P2, glucose-6-P, and glucose, respectively. Hb FIb is a glycoprotein; the mechanism of its formation is unclear. Hb FIa1 and Hb FIa2 had significantly lower oxygen affinities and n values than the other minor components and the major Hb F0. Moreover, 2,3-diphosphoglycerate did not influence the oxygenation of the minor or the major fetal Hb components. Incubations of Hb F with [14C]hexoses and subsequent chromatographic separation of hemoglobins and their globin chains confirm the previous findings that the binding of carbohydrate to Hb involves both specific and nonspecific reactions.

2,3-Diphosphoglycerate↗
PubMed1979

On the chromatographic heterogeneity of human fetal hemoglobin.

Minor fetal hemoglobins in red cell hemolysates of newborn and adults with elevated levels of Hb F have been separated and quantitated by Biorex 70 column chromatography. In addition to Hb F1, other minor hemoglobin zones eluting before F1, pre-F1, and after F1, post-f1 have been observed. The relative amounts of the two pre-F1 zones and F1 are higher in the red cells of adults with 97--100% Hb F (homozygous hereditary persistence of fetal hemoglobin, homozygous deltabeta-thalassemia and homozygous beta0-thalassemia) than in the red cells of an adult with homozygous beta+-thalassemia with 66% Hb F, a child with a trisomy-D-13 having 38% Hb F, and in two newborn. Hb F was glycosylated in vitro with [14C]glucose or [14C] glucose 6-phosphate, and was acetylated using chicken reticulocyte lysate or a crude acetyltransferase preparation isolated from the same lysate with [14C]acetyl-CoA as substrate. Chromatographic analyses indicated that the Hb F1 zone can be formed both by glycosylation and acetylation of Hb F, and that pre-F1 zones can be products of the reaction of Hb F with phosphorylated glycolytic intermediates. Biosynthesis of minor hemoglobins in reticulocytes was studied with [14C]leucine in the presence and absence of cycloheximide and by pulse-chase. The resulting data indicate that Hb F1 synthesis is dependent upon Hb F synthesis and that the posttranslational modification may take place at an early stage in Hb F synthesis.

Acetylation↗
PubMed1979

Microchromatographic quantitation of fetal hemoglobin in patients with sickle cell disease.

A microchromatographic procedure (Isolab Fast Hb Test System) which was developed for the quantitation of Hb AI (10) has been found useful for the quantitation of Hb F in samples that contain Hb S and/or Hb C but no Hb A (% Fmicro). This method has been evaluated through analyses of known mixtures of Hb F and Hb S. The Hb Fmicro levels in patients with sickle cell anemia and related conditions were compared with results obtained by alkali denaturation (% FAD) and conventional DEAE-cellulose chromatography (% FDE). This microchromatographic technique is a fast, simple, and sensitive method for Hb F quantitation in patients with Sickle cell disease.

Adult↗