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Biomedical subjects

J Rosa

Publications and source records attributed to J Rosa.

At least 91 records · Page 5Linked to original sources
PubMed1987

[Hemoglobin Boumerdès alpha 2(37) (C2) Pro----Arg beta 2: a new variant of the alpha chain associated with hemoglobin S in an Algerian family].

We report the first case of Hb Boumerdes, an alpha chain variant alpha 2(37) (C2) Pro----Arg beta 2, in an Algerian family. The propositus was also homozygous for the sickle cell gene. The abnormal hybrid Hb alpha 2Boum. beta 2S had an electrophoretic mobility on cellulose acetate pH 8.7 electrophoresis between those of Hb S and Hb A2. Its expression was about 16%. The alpha 2Boum. beta 2A fraction has a mobility between those of Hb F and Hb S. The effects of this mutation on Hb oxygen affinity and deoxy Hb S polymer formation were not studied. The propositus' sickle cell phenotype was benign.

Adolescent↗
PubMed1986

A 13C-NMR study of mutant hemoglobins with altered oxygen affinity.

The 13CO-NMR spectra of carbonylhemoglobins Saint Mandé (beta 102Asn----Tyr), Malmö (beta 97His----Gln), Hôtel Dieu (beta 99Asp----Gly) and Ao have been determined. The positions of the 13CO resonances for hemoglobins Ao, Malmö and Hôtel Dieu were similar indicating similar ligand environments for all. The 13CO resonance for the beta-subunit of Saint Mandé was upfield-shifted compared to the others. This is evidence that structural changes at the beta 102 position directly affect iron-ligand bonding as well as quaternary structure.

Carbon Isotopes↗
PubMed1986

High resolution NMR studies of histidine-substituted and histidine-perturbed hemoglobin variants. Histidine assignments, electrostatic interactions at the protein surface, and implications for hemoglobin S polymerization.

The aromatic region of the proton NMR spectrum of human adult hemoglobin (HbA) contains resonances from at least 11 titratable histidine residues. Assignments for five beta chain histidines have previously been proposed. In order to further characterize the aromatic spectra of HbA we studied 11 histidine-substituted and -perturbed hemoglobin variants in oxy and deoxy states and at different pH values by 400 MHz NMR spectroscopy. We propose assignments for the resonances corresponding to the C2 protons of His alpha 20, His alpha 72, His alpha 112, and His beta 77 in oxy and deoxy spectra and of His beta 97 and His beta 117 in deoxy spectra. Our assignments for His beta 2 and His beta 117 in the oxy state agree with those previously reported for the CO form, but in the deoxy state our spectra suggest a different assignment. Studies with Hb variants in which a histidine is perturbed by a neighboring substitution suggest additional assignments for His alpha 50 and His alpha 89 and demonstrate a strong dependence of the imidazole ring pK on hydrogen bond interactions and on the net charge of neighboring residues. Some of the newly proposed assignments of histidine resonances are used to discuss specific intermolecular interactions implicating His alpha 20, His beta 77, and His beta 117 in deoxy HbS polymers.

Electrochemistry↗
PubMed1986

Glycerated hemoglobin, alpha 2A beta 2(82) (EF6) N epsilon-glyceryllysine. A new post-translational modification occurring in erythrocyte bisphosphoglyceromutase deficiency.

A new minor Hb fraction initially designated Hbx, has been found in the hemolysate of an erythremic patient that we have previously described with a complete erythrocyte bisphosphoglycerate mutase (EC 5.4.2.4) deficiency. Hbx (3.5% of the total) was detected by isoelectric focusing and exhibited electrophoretic and chromatographic properties similar to those of several variants of the Hb central cavity. By density fractionation of red cells, it was demonstrated that Hbx was an aging hemoglobin as in the case of glycated Hb A1c. Functional studies revealed a low oxygen affinity and almost complete inhibition of the allosteric effect of the organic phosphate effectors. Structural studies demonstrated an absence of tryptic cleavage between the peptides beta T9 and beta T10 suggesting the presence of an adduct on Lys beta 82 or on a neighboring residue. Fast atom bombardment mass spectrometry and a specific enzymatic assay with glyoxylate reductase demonstrated that the beta 82 adduct was a glycerate moiety. It was concluded that Hbx was a glycerylated Hb, alpha 2A beta 2(82) (EF6) N epsilon-glyceryllysine, to our knowledge the first example of glycerylated protein. The mechanism of formation of glyceryl Hb, which was found in the four studied subjects with a bisphosphoglyceromutase deficiency, remains to be determined.

Amino Acids↗
PubMed1986

Disulfide scrambling of interleukin-2: HPLC resolution of the three possible isomers.

Native interleukin-2 (IL-2) contains three cysteines; two exist in a disulfide bridge (Cys-58 and Cys-105) and the third Cys-125 is a free sulfhydryl. In the presence of 6 M guanidine hydrochloride at alkaline pH, IL-2 is converted into three isomers. Each isomer represents one of the three possible disulfide-linked forms that can be generated from three cysteines. These three isomers were resolved on a C4 reverse-phase HPLC system. The identity of each of the three forms was determined by carboxymethylation of the free cysteines in each isomer with [3H]iodoacetic acid followed by determination of the labelled cysteines by tryptic peptide mapping. Tryptic peptide mapping of the more predominant of the two scrambled peaks showed it to be the Cys-105-S-S-Cys-125 linked form of IL-2. A Ser-125 construction of IL-2, which lacks a free cysteine, did not scramble under these conditions. These experiments demonstrate the utility of reverse-phase HPLC in studies of protein folding and disulfide bond structure.

Amino Acid Sequence↗
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↗
PubMed1986

Cloning and sequencing of mRNAs coding for two adult alpha globin chains of the salamander Pleurodeles waltlii.

A cDNA library of erythrocyte mRNAs was established from immature red blood cells of the adult amphibian, Pleurodeles waltlii (urodele; salamander). The cDNA clones corresponding to the four adult globin chains were first identified and characterized by positive selection and the cDNAs derived from the two (major and minor) alpha-globin chains sequenced. The sequences presented contain both the complete 3'-noncoding region and the coding region of both chains, with the exception of the first nine codons of the minor alpha-chain, and a portion of the 5'-noncoding region of the major chain. The amino acid sequences of the encoded alpha-globin polypeptides have been deduced and compared with those of Xenopus laevis and of man. These comparative studies suggest that the alpha-globins of Pleurodeles waltlii and Xenopus laevis may have diverged from a common ancestral gene at the time when mammalian and amphibian lines diverged, and that they then evolved separately. Duplication of the alpha-gene, which is responsible for the polypeptide heterogeneity, appears to have occurred earlier in Pleurodeles waltlii than in Xenopus laevis.

Amino Acid Sequence↗
PubMed1986

Hemoglobin S Antilles: a variant with lower solubility than hemoglobin S and producing sickle cell disease in heterozygotes.

We have found a sickling variant, Hb S Antilles, alpha 2 beta 2(6 Glu----Val, 23 Val----Ile), that has the same electrophoretic mobility as Hb S but a distinct isoelectric focus and produces sickling in the carriers of the Hb A/S Antilles trait. The carriers' erythrocytes tend to sickle at O2 partial pressures similar to those that induce sickling in Hb S/C disease. Pure deoxy-Hb S Antilles is 50% as soluble as deoxy-Hb S (saturating concentration = 11 g X dl-1 compared to 18.4 for Hb S). Dilute solutions of pure Hb S Antilles have a lower oxygen affinity than those of Hb A or Hb S (partial pressure for 50% binding is 9 mm Hg compared to 5.5 mm Hg for Hb A or S at pH 7.00). A/S Antilles erythrocytes have a much lower oxygen affinity than A/S cells; this is further decreased in dense cells fractionated on a Percoll density gradient. Their oxygen equilibrium curves had anomalous shapes like those of S/S cells. Fiber formation in the erythrocytes of Hb S Antilles carriers is clearly due to its low solubility and oxygen affinity, showing that heterozygosity for this hemoglobin presents another sickle cell syndrome and suggesting that Hb S heterozygotes who exhibit symptoms of sickle cell disease should be carefully screened for double mutations.

Amino Acid Sequence↗
PubMed1986

Interaction of hemoglobin Siriraj with hemoglobin S: a mild sickle cell syndrome.

Hb Siriraj is a beta chain variant in which beta 7 (A4) Glu is replaced by a lysine. It has been encountered in association with Hb S in a black man from Martinique. Some properties of Hb Siriraj are compared, particularly, with Hb C [alpha 2 beta 26(A3)Glu----Lys], and a study of its in vitro interaction with Hb S is discussed.

Amino Acid Sequence↗
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↗
PubMed1986

[DNA polymorphism in beta-thalassemia: a study of 15 families in Tunisia].

In order to perform prenatal diagnosis of beta-thalassemia by DNA analysis in Tunisia, we investigated molecular defects and their frequencies. We have determined which haplotypes are associated with beta zero or beta +-thalassemia phenotypes. Six of the haplotypes described by Orkin were observed among 15 patients homozygous for beta zero (11) or beta +-thalassemia (4). We also investigated the molecular defects. The frameshift mutation in codon 6, characterized by Mst II seems more frequent than the beta 39 non sense mutation indicating that Tunisian patients differ from other Mediterranean patients from Algeria or Italy. Results concerning beta +-thalassemia are too preliminary to draw any conclusion. The study is currently being enlarged with other molecular probes and restriction enzymes.

DNA↗
PubMed1986

[Screening for hemoglobinopathies and G6PD deficiencies in Morocco].

Screening for abnormal hemoglobins and G6PD deficiency was conducted in adult and new born Maroccans from Casablanca. The results presented deal with HbS and HbC traits, alpha, gamma, and delta mutations, the presence of detectable amount of Hb Bart's and the G6PD deficiency frequency.

Adult↗
PubMed1986

[Epidemiologic study of hemoglobinopathies in the Congo in 2,257 newborn infants].

A systematic examination of 2,257 Congolese newborns from Brazzaville for abnormal hemoglobins has been conducted. Gene frequency for HbS was 0.117; no HbC was found. Of the sample 14.4% had detectable amounts of Hb Bart's. Beta-thalassemia trait frequency was approximately estimated to 0.3%, 5 mutations of gamma chain, and 1 mutation for alpha chain were detected.

Anemia, Sickle Cell↗
PubMed1986

Hémoglobinopathies in France.

A first approximation of the incidences of abnormal hemoglobin traits in France is given. The data include all the large ethnic minorities living in France, and also take into account the second and third generations. We estimate 1.3 X 10(5) and 1.8 X 10(5) individuals with HbS trait and beta-thalassemia trait respectively.

Anemia, Sickle Cell↗
PubMed1986

Hb Kokura alpha 2 47 (CE5) Asp----Gly beta 2 in a French Jewish family.

An abnormal hemoglobin was found in a young polycythemic man. Case study showed that the polycythemia was not due to hemoglobinopathy as the blood oxygen affinity was normal. Structural study of this variant permitted the characterization of a Hb Kokura alpha 2 47 (CE5) Asp----Gly beta 2 for the first time in France.

Adult↗
PubMed1985

Structural and functional studies of hemoglobin Poissy alpha 2 beta 2(56) (D7) Gly----Arg and 86 (F2) Ala----Pro.

Hemoglobin Poissy alpha 2 beta 2(56) (D7) Gly----Arg and 86 (F2) Ala----Pro, is a new variant of the beta chain with two substitutions within the second exon of the corresponding gene. The electrophoretic mobilities are identical to those of Hb Hamadan alpha 2 beta 2(56) (D7) Gly----Arg as is the fingerprint of the tryptic hydrolysate of the two abnormal beta chains. The second substitution beta 86 Ala----Pro was detected by high-pressure liquid chromatography. Hb Poissy has a threefold increase in oxygen affinity with low Hill coefficient and diminished Bohr effect, which are restored to normal upon addition of 2,3-bisphosphoglycerate. Since the functional properties of Hb Hamadan (beta 56 Gly----Arg) have been described as normal, the abnormal function of Hb Poissy may be attributed to the beta 86 (F2) Ala----Pro substitution. Hb Poissy exhibits a mild instability and a greater reactivity of the thiol groups of the beta 93 (F9) Cys residues in the deoxy form than does Hb A. The oxidation rate of Hb Poissy is biphasic indicating a large inequivalence between the alpha and beta hemes. Thereafter NMR studies demonstrated that the beta 86 Ala----Pro substitution produces a displacement of the F helix closer to the heme plane and a large increase in the dynamic fluctuations of the tertiary structure on the proximal side of the beta hemes. These results lead to the conclusion that the beta 86 Ala----Pro substitution produces a destabilization of the F helix extending downwards to the FG corner and altering both the beta hemes and the alpha 1 beta 2 contacts.

Amino Acids↗