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At least 919 records · Page 51Linked to original sources
PubMed1989

Distal His----Arg mutation in bovine myoglobin results in a ligand binding site similar to the abnormal beta site of hemoglobin Zurich (beta 63 His----Arg).

Carbon monoxide binding to a myoglobin mutant with distal arginine in place of histidine has been examined. The mutant is derived from a cDNA clone for Mb mRNA from fetal bovine skeletal muscle. The mutation only slightly perturbs visible/Soret spectra whereas the infrared spectrum of liganded CO is greatly modified to become nearly identical to Hb Zurich beta-subunit spectrum. The mutant IR spectra differ substantially from spectra of wild-type MbCO and normal HbCO beta-subunit. For both the Mb and the Hb the distal His----Arg mutation increases the affinity for CO and reduces the number of observed conformers. These results demonstrate that this mutation greatly reduces the differences between Mb and Hb in the structure and properties of its ligand binding sites.

Animals↗
PubMedDate not supplied

Care of the child with sickle cell disease: acute complications.

Sickle cell disease (SCD) is a term used to describe a group of genetic disorders of hemoglobin production characterized by a predominance of the abnormal hemoglobin known as hemoglobin S. Common acute complications of SCD in children requiring hospitalization include painful episodes, febrile illness, and splenic sequestration. The staff nurse has an important role in providing prompt treatment and instituting preventative measures to avoid the adverse clinical outcomes of SCD such as acute chest syndrome, severe anemia, cardiovascular instability, and bacterial sepsis. A basic understanding of the pathophysiology of vaso-occlusion, the immune system, hemolysis, and the spleen is essential in the care of a child during an acute complication of SCD. Additionally important are a knowledge of the genetics, pathophysiology, medical and nursing management, and a familiarity with patient and family education material relating to sickle cell disease.

Anemia, Sickle Cell↗
PubMedDate not supplied

[Risks of confusion in the laboratory detection of drepanocytosis (author's transl)].

A brief review of the most usual methods for detecting hemoglobin S, their principles, their limits and interpretations. The author, then, considers the identification of hemoglobin S either isolated or associated with other abnormal hemoglobins or with thalassemiae. He emphasizes the techniques preventing some confusion in results interpretation. Problems in identifying HbS in new-born baby are also considered.

Anemia, Sickle Cell↗
PubMed1996

[Analysis of abnormal erythrocyte proteins and the etiological relation to hemolytic anemia].

Analytical procedures and diagnostic methods on abnormal proteins associated with hemolytic anemia are reviewed. Hemoglobin variants and enzymopathies are disorders of soluble proteins in erythrocytes. Electrophoretic mobilities and enzyme assay are clinically most useful to detect the disorders. Unique methods have been devised for unstable hemoglobins. Abnormal skeletal proteins are responsible for some spherocytosis and related diseases. Disorder of proteins which have penetrated into the membrane may cause similar hemolysis. Complement regulatory proteins on the surface of membrane are defective in paroxysmal nocturnal hemoglobinuria. Flow-cytometric analysis is convenient for disclosing clonal abnormal erythrocytes. Antibodies are investigated after elution. Ultimate characterization for the erythrocyte proteins are performed on biochemical approaches, such as amino acid analysis by HPLC and determination of base sequences of cDNA.

Anemia, Hemolytic, Congenital↗
PubMed1981

The biosynthesis of hemoglobin G San Josè (beta 7(A4) Glu replaced by Gly).

This report is concerned with the evaluation of hematological parameters and the percentage level of the abnormal hemoglobin (Hb) G San Josè as found in 4 heterozygous carriers from a family of Sicilian origin. Biosynthetic studies and in vitro recombination experiments strongly indicate that abnormal beta chains are synthesized at lower rate than beta A chains and exhibit a minor affinity (relative to beta A chains) for complementary chains in a condition of relative aA chain deficiency. The possibility that the low affinity of beta G chains for a chains may play a decisive role in controlling the level of the abnormal Hb in the peripheral blood of the present non-a-thalassemic abnormal Hb carriers is therefore discussed.

Adult↗
PubMed1993

Hb Melusine [alpha 114(GH2)Pro-->Ser]: a new neutral hemoglobin variant.

Hb Melusine [alpha 114(GH2)Pro-->Ser] was found in an Algerian patient during a systematic screening for hemoglobinopathies performed in Luxembourg. The abnormal hemoglobin was suspected when a thickening of the Hb A band was observed by isoelectrofocusing. The mutant hemoglobin was silent in all other electrophoretic methods used for presumptive diagnosis with the exception of globin electrophoresis in the presence of Triton X-100. This technique revealed an alpha chain considerably more hydrophobic than normal. The structural abnormality of Hb Melusine concerns position alpha 114(GH2) that belongs to a cluster of hydrophobic residues localized in the N-terminal half of the alpha T-12b tryptic peptide. It has been shown in the case of another variant of that position (Hb Nouakchott), that the replacement of the Pro GH2 by a Leu was responsible for a dramatic increase in the retention time of the alpha polypeptide chain during reversed phase high performance liquid chromatography, much higher than that reported for similar substitutions in other regions of the hemoglobin molecule.

Adult↗
PubMed1978

Hemoglobin Lincoln Park: a betadelta fusion (anti-Lepore) variant with an amino acid deletion in the delta chain-derived segment.

An electrophoretically slow-moving hemoglobin variant was identified in three members of a family originating from Southern Mexico. The variant, Hb Lincoln Park, made up approximately 14% of the total hemoglobin and appeared to have normal stability and functional properties. None of the individuals in whom the abnormal hemoglobin was present was anemic, but each had a mildly elevated reticulocyte count. Structural data suggest that the non-alpha chain of Hb Lincoln Park represents a betadelta gene-fusion product, with normal beta chain structure of the amino-terminal portion of the chain and delta sequences subsequently, the crossover point occurring between animo acid residues 22 and 50. An additional abnormality is the deletion of valine-137, a component of the delta gene-derived segment of the betadelta chain. To account for the development of this abnormal globin chain, a series of intergenic crossovers is proposed; the first, a nonhomologous crossover between the beta and delta genes, presumably gave rise to the betadelta fusion gene; two additional crossovers, one of them unequal, may then have occurred between the same beta and delta genes to produce the amino acid deletion.

Adult↗
PubMed1975

Hemoglobin Syracuse (alpha2beta2-143(H21)His leads to Pro), a new high-affinity variant detected by special electrophoretic methods. Observations on the auto-oxidation of normal and variant hemoglobins.

Family members from four generations were found to have polycythemia and increased whole blood O2 affinity (P50; 11 mm Hg; normal, 27 mm Hg). No abnormal hemoglobin bands were seen after electrophoresis on starch gel at pH 8.6 or agar gel at pH 6.0. Analysis of the oxygenated hemolysate by isoelectric focusing on polyacrylamide gel revealed two closely spaced bands. When deoxygenated hemolysate was analyzed in oxygen-free gels, the two components were more widely separated. About 40% of the patient's hemoglobin focused at a more acid pH than hemoglobin A, indicating a hemoglobin variant with impaired Bohr effect. Chromatography of globin in 8 M urea revealed two beta-chain peaks, the first of which was eluted at a lower buffer molarity than normal beta chain. Fingerprints of tryptic digests of the aminoethylated chains were done on silica gel thin-layer plates. Tp 14 from the abnormal beta chain had slower electrophoretic mobility and a greater Rf value. Amino acid analyses of this peptide gave values identical with those of betaTp 14, except that it contained one proline residue and no histidine. Since the one His in betaTp 14 is in position 143, hemoglobin Syracuse in alpha2beta2-143 His leads to Pro. Native Hb Syracuse could be separated from hemoglobin A on a carboxymethylcellulose column. The inclusion of 0.1 mM EDTA in the preparative buffers proved very useful in reducing the formation of methemoglobin. Oxygen equilibria of purified hemoglobin Syracuse showed high oxygen affinity (P50 value 12% that of hemoglobin A) and lack of cooperativity between subunits (Hill's n equals 1.1). The alkaline Bohr effect was about half that of hemoglobin A. The proline substitution at betaH21 disrupts the helical configuration and probably prevents the formation of salt bonds that are important in stabilizing the deoxy structure and contribute to the alkaline Bohr effect. Since beta143 His is a binding site for 2,3-diphosphoglycerate (2,3-DPG), it is not suprising that hemoglobin Syracuse had markedly impaired reactivity with 2,3-DPG. Hemoglobin Syracuse auto-oxidized more slowly than hemoglobin A, probably reflecting a slower rate of dissociation of oxygen from fully liganded hemoglobin.

Adult↗
PubMed2005

Hb Stara Zagora: a new hyper-unstable hemoglobin causing severe hemolytic anemia.

We describe a new hyper-unstable beta chain variant (codons 137-139, -6 bp) in a 2-year-old Bulgarian boy. The abnormal hemoglobin (Hb) is associated with severe hemolytic anemia as a consequence of its hyper instability. The child was admitted to the Pediatric Clinic (Faculty of Medicine, Stara Zagora, Bulgaria) at the age of 2 months. Because of anemia (Hb 6.9 g/dL) and high serum iron level (58 microM/L) the child was transfused. However, a month later his Hb level had dropped to 7.5 g/dL, and since then he has been on a regular monthly blood transfusion regimen. Hemoglobin analysis of a blood sample collected 2 months after the last transfusion at the age of 2 years, revealed no abnormalities except for the presence of inclusion bodies after incubation of peripheral blood with brilliant cresyl blue. Sequencing of the beta-globin gene revealed heterozygosity for a 6 bp deletion (-TGGCTA) at codons 137 [the second and third base pair (bp)], 138 and 139 (the first bp), forming a new codon at position 137 (GAT). This event eliminates three amino acids (Val-Ala-Asn) and introduces a new residue (Asp). It creates a new restriction site for HphI. The parents and his dizygotic twin brother had no history of hemolysis. The paternity of the child was confirmed by DNA analysis.

Anemia, Hemolytic↗
PubMed1993

Unstable alpha-chain hemoglobin variants with factitious beta-thalassemia biosynthetic ratio: Hb Questembert (alpha 131[H14]Ser-->Pro) and Hb Caen (alpha 132[H15]Val-->Gly).

Hb Questembert [alpha 131(H14)Ser-->Pro] was found in several members of a French family suffering from congenital Heinz body anemia. The unstable hemoglobin was expressed in the peripheral red blood cells at a very low level. Globin biosynthetic studies revealed a high specific activity of the abnormal chain and an alpha-/beta-labeling ratio similar to that of beta-thalassemia trait. Hb Caen [alpha 132(H15) Val-->Gly] is another unstable variant with the same globin biosynthesis abnormality. In both cases the structural modification is localized at the end of the H helix, a region encoded by the third exon. The mechanism for the unbalanced globin synthesis is not yet clear. It may be related 1) to a defect in chain assembly, 2) to an increased rate of degradation of the variant chain followed by the release of unlabeled beta-chains from the abnormal hemoglobin, thus leading to an apparent suppression of beta-chain synthesis, or 3) to a modified stability of the abnormal alpha-globin mRNA.

Adult↗
PubMed1982

A hemolytic plaque assay for the detection of red blood cells carrying abnormal or mutant hemoglobin.

A simple hemolytic plaque assay for the detection of red blood cells carrying abnormal or mutant hemoglobin is described. The assay is based on the use, as indicator cells, of sheep red blood cells coated with monospecific antibody against the hemoglobin variant, another complement fixing multispecific anti-hemoglobin antibody as developing serum and an antibody against red cell ghosts which can lyse only the red cells of the species being studied and not the indicator sheep red cells. The test red cells are mixed with the indicator sheep red cells, the developing antiserum and the anti-ghost antibody. The mixture is transferred into thin chambers prepared with 2 microscope slides and incubated at room temperature (25 degrees C). The indicator sheep red cells around each test red cell carrying abnormal or mutant hemoglobin are lysed resulting in the formation of a plaque. Instead of anti-hemoglobin-coated sheep red blood cells, protein A-coated sheep red blood cells may be used as indicator cells provided the developing antiserum is monospecific for the hemoglobin variant. When sheep red blood cells coated with an antibody specific for DBA/2J mouse hemoglobin were used in the assay, only red cells from DBA/2J mice (carrying d hemoglobin) formed plaques while C57BL/6J red cells (carrying s hemoglobin) did not.

Animals↗
PubMed1978

Genetic diversity in hemoglobins. Disease and nondisease.

Recent mass screening programs for sickle cell trait have been the first large-scale efforts to detect potentially deleterious genes and to provide genetic counseling to healthy carriers. In these programs, the expected prevalence of sickle hemoglobin and hemoglobin C has been found, and other mutant hemoglobin genes have also been uncovered. Many of these are not associated with disease, but simply reflect normal genetic diversity. A paradox of this finding is illustrated when, in counseling, many persons demonstrate difficulty in understanding that though they have an abnormal hemoglobin gene, they themselves are not ill or abnormal. The problem's solution lies in educating both health professionals and the public so that the normal existence of considerable genetic diversity is recognized. Since every person may carry mutant genes, whether potentially deleterious or innocuous, our definition of normal must be revised.

Genes↗
PubMed1998

Qualitative and quantitative analysis of hemoglobin variants by capillary isoelectric focusing.

We developed two capillary isoelectric focusing (CIEF) assays, in narrow pH gradients, with the aim of routinely separating and quantitating normal and abnormal hemoglobins (Hbs): a one-step CIEF assay where residual electroosmotic flow mobilizes the proteins during focalization, and a two-step CIEF assay where focused Hbs are mobilized by low pressure by maintaining high-voltage. The resolution of 0.10 pH unit obtained with the one-step assay allowed the separation of the Hbs A, F, S and C; but Hb A2, which represents about 2-3% of whole Hb, could not be quantitated. The better resolution of 0.02 pH unit obtained with the two-step assay allowed the separation of some Hb variants of very close isoelectric points. The reproducibility of retention times was satisfactory (C.V.<5%). Moreover, in this configuration quantitation of Hb A2, Hb F and Hb S led to a standard deviation of less than 5%, allowing the diagnosis of thalassemias. The one-step assay could be useful only for the detection of abnormal variants, while the two-step assay could be applied to the routine analysis of Hbs, with quantitation of minor fractions and presumptive identification of variants.

Electrochemistry↗
PubMed1989

Hemoglobin Hope found in a patient with basal cell carcinoma of the genial region.

Hemoglobinopathy was detected in a 72-year-old female with basal cell carcinoma of the genial region during high-performance liquid chromatography of hemolysate for the assay of HbA1c. Structural analysis demonstrated that this abnormal hemoglobin was identical to Hb Hope [beta 136(H14)Gly----Asp]. No clinical or hematological abnormality was observed. A study of the family revealed that a younger sister and two sons of the propositus had the same hemoglobin variant. This is the second observation of Hb Hope in a Japanese family.

Aged↗
PubMed1968

Hemoglobin Hijiyama: a new fast-moving hemoglobin in a Japanese family.

A variant of hemoglobin A, named Hb Hijiyama, found in two generations of a Japanese family living in Hiroshima, Japan, has a higher anodal electrophoretic mobility than hemoglobin A; a gain of two negative charges per molecule is indicated. Fingerprinting and amino acid analysis showed the biochemical anomaly to be in the beta chain at residue 120, where lysine is replaced by glutamic acid. In the heterozygote carriers of the abnormal hemoglobin there is no apparent association with clinical or hematologic abnormalities.

Adult↗