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PubMedDate not supplied

The effect of abnormal hemoglobins on the membrane regulation of cell hydration.

Several hemoglobinopathies are associated with abnormalities in the permeability of the red cell membrane, in some cases leading to permanent alterations of the intracellular milieu. Homozygous sickle cell disease is the most thoroughly studied example. Deoxygenation of sickle cells causes a transient increase in the permeability to monovalent cations and Ca; prolonged deoxygenation can lead to a permanent accumulation of Ca and loss of total cations and water. Although the mechanisms for the permeability changes are not yet defined, mechanical stress on the membrane, with subsequent damages by excess Ca or membrane-associated hemoglobin have been suggested to play a role. Loss of cell water and increase in mean cell hemoglobin concentration causes massive reduction of cell deformability in the oxygenated state and makes the hemoglobin more likely to undergo sickling because of the strong concentration dependence of the sickling process. Limited evidence suggests the occurrence of permeability defects in other hemoglobinopathies and the thalassemias. The suggested alterations range from a slight increase in K permeability of incubated thalassemia cells to substantial dehydration of cells from patients with homozygous hemoglobin C disease. Oxidative damage to the membrane, involving an abnormal hemoglobin-membrane association, may underly the permeability changes in these cells.

Adenosine Triphosphate↗
PubMed1996

[A case of abnormal hemoglobin (HbJ Cape Town) with high serum levels of HbAlc].

We describe a case of hemoglobinopathy detected on admission for examination for high blood glucose levels and abnormal liver function. In 1991, it was pointed out that he had postprandial hyperglycemia. In 1994, at age 60, he had lassitude and anorexia. He was admitted to our hospital on the suspicion of diabetes mellitus and liver disease. Glycosylated hemoglobin levels was very high, but the 75 gram oral glucose tolerance test result was within the normal range. After abstinence from alcohol, his glutamic oxaloacetic transaminase, glutamic pyruvic transaminase and gamma glutamyl traspeptidase became normal. Diabetes was excluded and abnormal hemoglobinopathy had been suspected. We analyzed his abnormal hemoglobin. In isoelectro-phoresis a fast moving variant was detected suggesting the presence of abnormal hemoglobin at the cathode. We fractionated hemolytic globin by CM-chromatography and detected an abnormal peak before the alpha chain band. Subsequently, we sequenced isolated abnormal alpha chain and detected the substitution of Ariginine for Glutamamine at position 92 (Hb J Cape Town). So far he has not demonstrated any symptoms or signs of HbJ Cape Town. Hemoglobinopathy is not uncommon in aged people.

Amino Acids↗
PubMed1980

Oxygen affinity and stability of hemoglobin Dunn alpha 6(A4)Asp replaced by Asn): use of isoelectric focusing in recognition of a new abnormal hemoglobin.

A new slow-moving hemoglobin was found in low proportion in an asymptomatic black woman. Isoelectric focusing helped to distinguish it from other hemoglobins with similar electrophoretic mobility, and amino acid analysis showed that aspartic acid alpha 6 (A4) had been replaced by asparagine. Oxygen affinity was increased, but the Bohr and DPG effects were normal. Stability of the purified hemoglobin was decreased, but that of hemolysates was normal. Abnormal oxygen affinity of this variant, and that of hemoglobin Sawara (alpha 6(A4)Asp replaced by Ala), may reflect loss of a salt bridge between Asp alpha 6 and Lys-alpha 127(H10) which would tend to favor the high-affinity R conformation of the molecule.

Adult↗
PubMed1986

[Abnormal hemoglobins screened in Tunisia].

We report the complete data we have collected concerning abnormal Hb in Tunisia, and their local repartition. The highest frequencies are observed in the North-West countries.

Genetic Testing↗
PubMed1973

Hemoglobin abnormalities in neoplastic hematological disorders.

Fetal hemoglobin (F) and hemoglobin A(2) were estimated in 35 patients with malignant hematological disorders. In 9 out of 10 patients with morphological and cytochemical features of acute myeloblastic leukemia the hemoglobin F was greater than 2%. Of the other 25 patients investigated only one patient with polycythemia rubra vera had a hemoglobin F level of more than 2%. Estimation of fetal hemoglobin may be of value in the classification of acute leukemias and the increased level observed probably reflects disturbed hemoglobin synthesis in the acute myeloblastic type.

Adolescent↗
PubMed1987

[Use of HPLC in different stages of characterization of abnormal hemoglobin. Application to a case of hemoglobin Grady (alpha-118 [+Glu-Phe-Thr])].

In this work the structural abnormality of Hb Grady was determined using mainly the high performance liquid chromatography (HPLC) technology. The methods described here are now easily available in an increasing number of laboratories. A small amount of the abnormal Hb (ca. 10 mg) was isolated by isoelectric focusing and its subunits fractionated by reversed phase HPLC. After tryptic or chymotryptic digestion the peptides were isolated by HPLC. Their amino-acid compositions were also determined by HPLC procedures following a precolumn derivatization.

Adult↗
PubMed1990

[Structural analysis of abnormal hemoglobin by the polymerase chain reaction (PCR) of genomic DNA].

Determination of the primary structure of abnormal Hbs on the basis of DNA sequencing of the globin gene obtained from a carrier of abnormal Hb was performed. DNA obtained from the leukocytes of the peripheral blood was amplified by the polymerase chain reaction (PCR) using the proper amplification primer set. Amplified DNA was digested with two different restriction endonucleases and cloned to vector M 13 mp 18 or mp 19, which had been digested with the same enzymes. DNA sequencing was done by the dideoxy chain termination method using T 7 DNA polymerase, and the abnormal Hbs whose primary structure was determined were as follows: Hb Fukuoka [beta 2 His(CAC/T)----Tyr(TAT)], Hb Machida [beta 6 Glu(GAG)----Gln (CAG)], Hb Hope [beta 136 Gly(GGT)----Asp(GAT)], Hb Hiroshima [beta 146 His(CAC)----Asp(GAC)] and Hb Kodaira [beta 146 His(CAC)----Gln(CAA)]. This method for determining the primary structure of abnormal Hbs might be more effective than the ordinary method, which involves amino acid analysis and amino acid sequencing of the abnormal peptide obtained from abnormal Hb.

DNA↗
PubMed1972

Oxygen equilibrium characteristics of abnormal hemoglobins. Hirose (alpha-2-beta-2-37Ser), L Ferrara (alpha-2-47-Gly-beta-2), Broussais (alpha-2-90-Asn-beta-2), and Dhofar (alpha-2-beta-2-58Arg).

The oxygen equilibrium characteristics of four structural variants of hemoglobin A were correlated with their amino acid substitutions. Hemoglobin Dhofar, in which the proline at E2(58)beta is replaced by arginine, had normal oxygen equilibrium characteristics. Hemoglobin L Ferrara. in which the aspartic acid at CD5(47)alpha is replaced by glycine, and hemoglobin Broussais, in which the lysine at FG2(90)alpha is replaced by asparagine, both showed a slightly elevated oxygen affinity; nevertheless both demonstrated a normal heme-heme interaction and a normal Bohr effect. Hemoglobin Hirose, in which the tryptophan at C3 (37)beta is replaced by serine, showed abnormalities of all oxygen equilibrium characteristics; i.e., increased oxygen affinity, diminished heme-heme interaction, and reduced Bohr effect.These results suggest that aspartic acid at CD5(47)alpha and lysine at FG2(90)alpha are involved in the function of the hemoglobin molecule, despite the fact that these positions are not located directly in the heme or the alpha-beta-contact regions. Tryptophan at C3(37)beta is located at contact between alpha(1)- and beta(2)-subunits. It is suggested that the substitution by serine might disturb the quarternary structure of the mutant hemoglobin molecule during transition from oxy-form to deoxy-form resulting in an alteration of the heme function.

Arginine↗
PubMed1986

Hemoglobin abnormalities. An evaluation on new-born infants and their mothers in a maternity unit close to Brazzaville (P.R. Congo).

In order to evaluate the polymorphism of hemoglobin in a population of Equatorial Africa, we undertook a prospective study of 146 births at a rural maternity hospital close to Brazzaville (P.R. Congo). This showed among the mothers 31 (22%) carriers of the sickle cell trait (AS), six with delta mutation, and two with beta-thalassemia trait. Among the children, 27 (18.5%) had sickle cell trait and one had sickle cell homozygosity. The frequency of the HbF Sardinia trait was 7.5%. This and other studies suggested a dilution gradient from Europe to Africa. Hemoglobin Bart's could be visually detected in 23.3% of the new-born babies. We attempted to distinguish between those infants with a high level of Hb Bart's (Bart's ++ group: 13.7%) and a group with a detectable Hb Bart's level that in our experimental conditions is between 1 and 2% (Bart's + group: 9.6%). Mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) were 88.6 +/- 5.7 fl and 29.0 +/- 2.1 pg in the Bart's ++ group; 94.5 +/- 10.9 fl and 30.6 +/- 4.1 pg in the Bart's + group; whereas they were 101.0 +/- 8.7 fl and 33.9 +/- 2.5 pg in the control group. Since iron deficiencies are very rare in new-borns and selecting according to published data on black people as homozygous alpha-thalassemia of the type I (-alpha/-alpha), individuals of the Bart's ++ group whose MCV was below 95 fl and MCV below 30 pg, the gene frequency is estimated to be 34% and that of heterozygotes (-alpha/alpha alpha) 45%. These high frequencies were confirmed in AS mothers: 45% showed a significant decrease of the S fraction.

Adult↗
PubMed1991

Familial pulmonary hypertension in association with an abnormal hemoglobin. Insights into the pathogenesis of primary pulmonary hypertension.

A kindred with a familial hemoglobinopathy and familial primary pulmonary hypertension with autosomal dominant transmission has been identified. Affected family members were obvious from their cyanosis due to a reduced affinity for oxygen by the hemoglobin variant. The mother and one child had clinical pulmonary hypertension, whereas two siblings had cyanosis and preclinical pulmonary vascular disease as evidenced by abnormal perfusion lung scans and elevated levels of fibrinopeptide A in the face of normal pulmonary hemodynamics. In one, pulmonary hypertension could be induced with exercise. The studies on this family support the hypothesis that primary pulmonary hypertension may be initiated by abnormalities of the pulmonary vascular bed that predispose to in situ thrombosis. The possible common genetic transmission of the two diseases offers the speculation that the gene that confers predisposition to pulmonary hypertension may be located near the gene responsible for beta globulin.

Beta-Globulins↗