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Biomedical subjects

E C Abraham

Publications and source records attributed to E C Abraham.

87 records · Page 5Linked to original sources
PubMed1978

Influence of mouse age and erythrocyte age on glutathione metabolism.

In order to determine whether the biological age of a mouse influences erythrocyte metabolism and erythrocyte aging in vivo, blood samples were collected from male C57/BL6J mice of different biological ages ranging from mature (10 months) to "very old" (37 months). In the very old mouse, compared with the mature mouse, the erythrocyte survival time was decreased, erythrocyte densities were increased, the concentrations of total free thiol and reduced glutathione, and glutathione reductase activity were decreased. Erythrocytes were separated into different density (age) groups by phthalate ester two-phase centrifugation or by albumin density-gradient centrifugation. The density-age relationship of erythrocytes was established by pulse-labelling with 59Fe in vivo and by subsequent determinations of specific radioactivity of erythrocyte fractions of different densities prepared during a chase period of 60 days. The age of erythrocytes in mice of all ages was directly related to density. Also, in older erythrocytes compared with younger erythrocytes, decreased concentrations of total free thiol and reduced glutathione, and decreased glutathione reductase activity were observed. These were the lowest in the old erythrocytes of very old mice. These results in aging erythrocytes from aging mice suggest that the glutathione status the erythrocyte may be an index of aging, not only of the cell but also of the organism.

Aging↗
PubMed1978

Is the trimodality of Hb Leslie (alpha 2 beta 2 131 Gln---O) in heterozygotes the result of a variable number of active alpha-chain genes? Evidence for posttranslational control of hemoglobin synthesis.

Whether the trimodality in the relative concentration of the hemoglobin variant Hb Leslie in heterozygotes (Huisman, Hemoglobin 1:349-382, 1977) is due to a polymorphism of the alpha-chain structural genes was investigated by conventional incubation of reticulocytes with 14C-leucine. In addition, an aliquot from each of the incubations was incubated under the same conditions but without isotope. Three Hb Leslie heterozygotes with presumably four, three (heterozygous alpha-thalassemia-2), and two (homozygous alpha-thalassemia-2) active alpha-chain genes and with 33%, 22% and 11% Hb Leslie respectively, and one patient with the Hb Leslie beta(0)-thalassemia condition with more than 85% Hb Leslie were studied. The data indicate that betaLeslie chains have a lower affinity for alpha chains that betaA chains. A concomitant alpha-chain deficiency results in a reduced incorporation of betaLeslie chains into the tetrameric Hb Leslie molecules, while the quantity of Hb Leslie produced correlates with the degree of alpha-chain deficiency. Excess of betaLeslie chains is preferentially degraded.

Female↗
PubMed1978

Variability in the interaction of beta-thalassemia with the alpha-chain variants Hb G-Philadelphia and Hb Rampa.

Two unrelated families are reported in which beta-thalassemia trait occurred with a heterozygosity of Hb G-Philadelphia (alpha2 68(E17)Asn leads to Lys beta2) in one family and with Hb Rampa (alpha2 95(G2)Pro leads to Ser beta2) in the other. The percentage of Hb G-Philadelphia was not influenced by the simultaneous presence of a beta-thalassemai determinant, but that of Hb Rampa was descreased from 20% in the simple heterozygote to about 6% in persons with the Hb Rampa-beta-thalassemia combination. Data from in vitro recombination experiments with isolated alpha X, alpha A, and beta A chains, with heme attached, indicated a preferential formation of Hb A over Hb Rampa but not over Hb G-Philadelphia in conditions of relative beta-chain deficiency. This suggests that the rate of assembly of monomers to form dimers or tetramers can be an important mechanism of controlling the quantity of certain hemoglobin variants with critical substitutions in heterozygotes.

Adolescent↗
PubMed1977

An improved chromatographic procedure for quantitation of human fetal hemoglobin.

The DEAE-cellulose chromatographic procedure which uses glycine-KCN-NaCl solutions as Developers and a NaCl gradient to elute the hemoglobin zones was found to be useful for the quantitation of Hb F in samples containing Hb A, provided the level of Hb F exceeds 2 percent. The method has been evaluted through a study of artificial mixtures and of blood samples from patients with various disorders. The data have been compared with results obtained by four other procedures that are used for the quantitation of Hb F.

Chromatography, DEAE-Cellulose↗
PubMed1977

Differences in affinity of variant beta chains for alpha chains: a possible explanation for the variation in the percentages of beta chain variants in heterozygotes.

The alpha and beta chains of the hemoglobins A, S, Leslie and N-Baltimore have been isolated as PMB derivates by CM-cellulose and DEAE-cellulose chromatography. The relative affinities of the betaA, betaS, betaLeslie and betaN-Baltimore chains for alpha chains were measured through quantitation by chromatography of the hemoglobins A and Leslie, A and S, and A and N-Baltimore that were formed when variable amounts of alpha chains were added to a mixture of equal amounts of the appropriate beta chains. The data indicate a greatly decreased affinity of betaLeslie chains for alpha chains; a similar preference of alpha chains for betaA chains was observed for mixtures involving alpha, betaA, and betaS chains, but the affinity of betaS chains for alpha chains was higher than that of betaLeslie chains. The betaN-Baltimore chains assembled with alpha chains at a similar rate as betaA chains. The data as interpreted indicate that the affinity of certain beta chains for alpha chains can be a major post-translational control mechanism which regulates the level of a beta chain variant in heterozygotes.

Chromatography, DEAE-Cellulose↗
PubMed1976

Hemoglobin Athens-Georgia, or alpha 2 beta 2 40(C6)Arg replaced by Lys, a hemoglobin variant with an increased oxygen affinity.

A new hemoglobin variant, termed hemoglobin Athens-Georgia, has been found in a 23-year-old Caucasian student and three members of her family. The electrophoretic mobility of this variant at pH 9.0 is slightly less than that of hemoglobin-A. Arginyl residue in position 40 of the beta chain, corresponding to position 6 of the C helix, has been replaced by a lysyl residue. This amino acid substitution is at the alpha1-beta2 contact and slightly affects the oxygen binding properties of the hemoglobin molecule. Hemoglobin Athens-Georgia has an increased affinity for oxygen, a normal heme-heme interaction and a normal Bohr effect. Hematological abnormalities are not associated with this variant.

Adolescent↗
PubMed1976

Quantitative microchromatographic determination of hemoglobin F in patients with hemoglobins S and/or C.

The improved microchromatographic procedure for the detection of Hb-S and/or Hb-C in cord blood at birth (Schroeder et al.: J. Lab Clin Med 86:528-532, 1975) as well as a modification thereof may also be used for the quantitative determination of Hb-F in the presence of Hb-S and/or Hb-C. However, Hb-A interferes and must be absent. The methods use 0.5 X 6 cm columns of CM-cellulose with Tirs or Bis-tris developers and require 2-4 hr to complete. At low percentages of Hb-F, the sharper zone of the Tris method is more easily visible than that of the Bis-tris method, but the latter is a somewhat more rapid procedure. About 300 cases with Hb-S and/or Hb-C have been examined by the microchromatographic procedure. Most of these results (Fmicro) have been compared with data from the determination of Hb-F by one or more of the following methods: alkali denaturation (FAD), conventional DEAE-Sephadex chromatography (FDES), or isoleucine analyses of zones from DEAE-Sephadex chromatography (FIle). The accuracy and precision of the microchromatographic method is estimated to be 5-10%. The microchromatographic methods require much less time than conventional chromatography but more time than alkali denaturation procedures. Compared to the latter, the new methods use whole blood and less blood and permit the physical separation of Hb-F.

Chromatography↗
PubMed1975

Oxidation-reduction potentials of human fetal hemoglobin and gamma chains. Effects of blocking sulfhydryl groups.

The oxidation-reduction equilibrium of the gamma chains of human fetal hemoglobin (Hb F) has been studied and compared with that of the alpha and beta chains of human adult hemoglobin (Hb A). The effects of the sulfhydryl (--SH) reagents, iodoacetate, iodoacetamide, and p-mercuribenzoate (PMB), on the three kinds of chains and on Hb F have been compared. The midpoint potentials (E-m) of all three sorts of chains are lower than those of tetrameric hemoglobin A or F. The E-m values of alpha chains are the lowest, E-m = 0.049 volt at 6 degrees, and are unaffected by pH change or by PMB treatment, at least from pH 6 to 8. The E-m values of beta-SH chains are higher; E-m = 0.102 volt at pH 7, decreasing to 0.050 volt at pH 8, both at 6 degrees. These results agree with those of Banerjee and Cassoly ((1969) J. Mol. Biol. 42, 337-349). They reported no effect of PMB on beta chains, but we find that 2 eq of PMB/chain raise E--M to 0.139 volt at pH 7 at 6 degrees, chiefly as the result of reaction at beta-93, not at beta-112. Carboxymethylation at beta-93 has an insignificant effect compared with that of PMB. The oxidation-reduction potential of gamma chains is similar to that of beta chains. E-m = 0.098 volt at pH 7 at 6 degrees, decreasing to 0.064 at pH 8 and 0.010 at pH 9. The effects of --SH reagents, reacting at position gamma-93 (the only --SH group present in gamma chains), are essentially the same as those seen with beta chains. The oxidation-reduction potential of Hb F is almost identical with that of Hb A, except for being 0.008 volt lower at pH 6 at 6 degrees. This agrees with the results reported by Flohe and Uehleke ((1966) Life Sci. 5, 1041-1045). PMB or iodoacetamide treatment lowers E-m by 0.02 to 0.03 volt, depending on the pH, from 6 to 9, in much the same way as previously reported for Hb A(Brunori, M., Taylor, J.F., Antonini, E., Wyman, J., and Rossi-Fanelli, A. (1967) J. Biol. Chem. 242, 2295-2300). The "residual oxidation Bohr effect" noted in Hb F can be attributed to the oxidation Bohr effect of the gamma chains. The apparent pK of the heme-linked water molecule was found at 25 degrees to be, for Hb F, 8.1; for gamma-SH chains, 7.85; for gamma-PMB chains, 8.35; and for gamma chains treated with iodoacetate, 7.80. Sedimentation coefficients, s-20, w, at a protein concentration of 5 mg/ml, were found to be, for fetal hemoglobin 4.09, for iodoacetamide-treated fetal hemoglobin 4.04, for PMB-treated fetal hemoglobin 3.41, for fetal gamma-SH chains 4.25, and for fetal gamma-PMB chains 3.08.

Adult↗
PubMed1975

Microchromatography of hemoglobins. IV. An improved procedure for the detection of hemoglobins S and C at birth.

Substitution of CM-cellulose for CM-Sephadex had yielded a superior microchromatographic method for distinguishing the AS, AC, SS, SC, and CC conditions at birth. On the translucent columns of CM-Sephadex, the hemoglobin zones are somewhat diffuse. However, the compact, well-defined zones on the CM-cellulose column facilitate the interpretation of the results even though the amount of sample is only 20 per cent as great. The CM-cellulose method is as simple and rapid as the original CM-Sephadex procedure.

Chromatography↗
PubMedDate not supplied

Separation of human hemoglobins by DEAE-cellulose chromatography using glycine-KCN-NaC1 developers.

This chromatographic procedure uses DEAE-cellulose as ion exchanger and glycine-KCN-NaC1 solutions as developers. Blood samples from several adults and newborn infants with alpha, beta, delta, or gamma chains variants have been analysed. The hemoglobins are eluted as compact and symmetrical zones, and the separation of many hemoglobin types is greatly improved. The procedure is relatively fast, simple, and inexpensive.

Adult↗