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Biomedical subjects

D Labie

Publications and source records attributed to D Labie.

At least 127 records · Page 7Linked to original sources
PubMed1981

[Polymorphism of hemoglobins D in Ivory Coast: Hb Korle Bu (beta 73 (E17) Asp leads to Asn), Hb Avicenna (beta 47 (CD6) Asp leads to Ala) and Hb Cocody (beta 21 (B3) Asp leads to Asn) (author's transl)].

A recent screening performed at the CHU Cocody in Abidjan (Ivory Coast) revealed six cases of hemoglobin "D". The use of a rapid strategy based on isoelectric focusing studies, finger-printing, reverse phase high performance liquid chromatography and solid phase microsequence technique led to the characterization of three abdominal hemoglobins. The first variant corresponded to the Hb Korle Bu (beta 73 (E17) Asp leads to Asn) (pI = 7.210) which is common in this country. The second, Hb Avicenna (beta 47 (CD6) Asp leads to Ala) (pI = 7.225) has not yet been reported in Africa. The last one was a new variant, Hb Cocody (beta 21 (B3) Asp leads to Asn) (pI = 7.205). A large number of hemoglobin "D" have been detected in European, American negroes, Amerindian or Asiatic populations, but only few observations were reported in Africa. Large screenings and discriminative methodologists must provide information on the polymorphism of hemoglobin D in the African population.

Chemical Phenomena↗
PubMed1981

Minor haemoglobin fractions in uraemic and in diabetic patients.

Using a high resolution automated chromatographic method, the levels of the different minor haemoglobins Hb A1a, A1b, and A1c were measured in 20 healthy controls, in 20 patients with chronic renal failure, in 20 uraemic patients on intermittent haemodialysis, and in 20 insulin-dependent diabetic patients. In uraemic non haemodialysed patients, the levels of the three minor fractions were increased significantly. The two fractions Hb A1b and A1c were normalised subsequent to haemodialysis, whereas the level of Hb A1a was higher in the haemodialysed than in the uraemic non haemodialysed group. In both groups of uraemic patients, no correlation was found between the minor Hb fractions and the corresponding serum creatinine, uric acid, urea, phosphorus, bicarbonate and blood glucose levels. In diabetic patients, the three minor fractions were increased. As expected, Hb A1c and glucose concentrations were tightly correlated. No correlation was found between blood glucose levels and Hb A1a, whereas a correlation existed between blood glucose levels and Hb A1b. It is concluded that the increase of minor haemoglobin fractions in renal failure does not only reflect the glucose intolerance. Renal failure itself causes an increase of the three minor fractions. Overall assay of the minor haemoglobin components (Hb A1) may lead to misinterpretation in case of diabetic patients with chronic renal failure.

Adult↗
PubMed1981

The sickle gene polymorphism in North Africa.

Analysis of the restriction endonuclease Hpa 1-beta globin gene linkage has been performed in a predominantly Arab population of North Africa possessing the sickle (beta A) gene is found associated with a 7.6 kilobase) or 7.0 kb Hpa 1 fragment (54/54 assignable beta A genes), whereas the beta S gene is found associated with a 13 kb Hpa 1 fragment (42/42 assignable beta S genes). The results demonstrate a very tight linkage of the beta S gene to the 13 kb Hpa 1 fragment as well as a very low probability that a beta A gene will be found on a 13 kb Hpa 1 fragment. Thus, the North African population presents a nearly ideal opportunity for prenatal diagnosis solely by Hpa 1-beta globin gene linkage analysis. Additionally, the evidence supports the hypothesis that the beta S gene flowed from West Africa rather than from Arab populations in the Middle East.

Africa, Northern↗
PubMed1981

[Recent data concerning abnormal hemoglobins (author's transl)].

The study of abnormal hemoglobins was oriented towards three criteria as a function of commonly encountered clinical problems : differentiation between frequent, relatively infrequent and exceptional hemoglobins ; systematic study of high-risk ethnic groups and isolated discoveries ; silent hemoglobinopathies and those accompanied by physiopathological repercussions such as hemolytic anemia, disturbance in oxygen transport and cyanosis. The chronology and rationale for these studies was discussed, with particular attention being given both to normalized baseline measures and to the new, high-resolution techniques such as isoelectric focalization. No attempt was made to provide an exhaustive list, but rather examples were provided illustrating the various points considered. Finally, a number of particular points are brought up to where a correctly made diagnosis can avoid the necessity of subjecting patients to long and possibly dangerous tests.

Anemia, Hemolytic↗
PubMed1981

Hemoglobin Barcelona beta 94 (FG1) Asp leads to His : a new hemoglobin Variant with increased oxygen affinity.

A new variant, Hb Barcelona (beta 94 Asp leads to His) found in a Spanish family presenting with a mild polycythemia, is described. Its increase in oxygen affinity is explained by the rupture of the salt-bridge between beta 94 Asp and beta 146 His which normally stabilizes the deoxystructure and accounts for approximately half of the Bohr effect. A comparison between the estimated oxygen transport to the tissues by the blood from a patient with Hb Kempsey and that of the patients with Hb Barcelona showed, in the latter cases, that an almost normal oxygen delivery was obtained by the increase of the hemoglobin level.

Chemical Phenomena↗
PubMed1980

Beta-chain contact sites in the haemoglobin S polymer.

The amino acid residues involved in the areas of contact that stabilise the haemoglobin S polymer fibre seem to be the same ones that stabilise the basic unit of the deoxyhaemoglobin S crystal: the Wishner-Love double strand. The haemoglobin S fibre is probably formed by a unique packing of these double strands.

Binding Sites↗
PubMed1980

[Polycythemia resulting from abnormal hemoglobin with increased affinity for oxygen. Two cases (author's transl)].

An abnormal hemoglobin with increased oxygen affinity has to be suspected in all the cases of polycythemia where no direct signs of "polycythemia vera", or any of the classical reasons for erythropoietic stimulation can be demonstrated. This fact is documented by two new observations, one concerning a 44 year-old man with Hb Kempsey, another concerning a 58 year-old woman with Hb Malmö. The diagnosis is based on a scrupulous electrophoretic study involving an isoelectric focusing on polyacrylamide gel, and, on the study of the oxygen binding properties of the red blood cells. This polycythemia being a compensatory mechanism allowing a normal oxygen delivery to the tissues has to be respected and a compromise must be found with the cardiovascular risk.

Adult↗
PubMed1980

Interaction between cytochrome b5 and hemoglobin: involvement of beta 66 (E10) and beta 95 (FG2) lysyl residues of hemoglobin.

In erythrocytes the reduction of oxidized hemoglobin (methemoglobin) is dependent upon an electron transport reaction between cytochrome b5 and methemoglobin. These two proteins are believed to form a complex whose bonding is principally determined by complementary charge interactions between acidic groups of cytochrome b5 and basic groups of hemoglobin. In order to refine this model, three surface lysyl hemoglobin variants--namely Hb N Baltimore beta 95 (FG2) Lys leads to Glu, Hb I Toulouse beta 66 (E10) Lys leads to Glu, and Hb I Philadelphia alpha 16 (A14) Lys leads to Glu--have been studied with respect to their reducibility and ability to bind cytochrome b5. In the two former variants, the substituted amino acids are located near the heme crevice; in the third one the substitution lies far from it. Substitutions of lysine for glutamic acid in positions beta 66 and beta 95 perturb the formation of the cytochrome b5--hemoglobin complex and result in a dramatic impairment of the cytochrome b5-mediated reduction, whereas the same mutation in position alpha 16 has no effect. We conclude that the lysine residues in positions beta 66 and beta 95 are directly involved in the binding of cytochrome b5. The three-dimensional structure of hemoglobin suggests that the cytochrome b5-binding domain of hemoglobin is constituted by four lysine residues surrounding the heme crevice in both alpha and beta chains. Similarities with other interacting hemoproteins are discussed.

Amino Acid Sequence↗
PubMed1980

Hemoglobins of an amphibia, the neotenous Ambystoma mexicanum. Complete amino-acid sequence of the alpha chain of the major component using automatic solid-phase Edman degradation.

The primary structure of axolotl (neotenous Ambystoma mexicanum) alpha chain has been determined. NH2-terminal sequence data were performed using the solid-phase method. Complete amino acid assignments were deduced from the sequences of peptides obtained after cleavage with cyanogen bromide; the methionine-containing peptides, isolated from alpha chain tryptic digest, allowing the alignment of these fragments. All overlaps have been clearly established. Axolotl alpha chain contains 142 residues, one extra phenylalanine residue being located at its N terminus, when compared with mammalian alpha chains. The amino acid sequences of this polypeptidic chain and of an other urodele, the newt Taricha granulosa, show 44 differences with only 18 non-isopolar replacements. Homologies between various vertebrate alpha chains are briefly discussed.

Ambystoma↗
PubMed1979

Titration curves of polypeptide chains by combined isoelectric focusing-electrophoresis in 8 M urea.

Titration curves of reduced and alkylated polypeptide chains can be successfully performed in 8 M urea-polyacrylamide gel plates by electrophoresis perpendicular to a stationary stack of focused carrier ampholytes. All buffers and thiol reagents with pK values in the range pH 3--10 should be removed, since their pH-dependent ionization affects the migration and apparent pI values of the protein chains. No blurring of the patterns below pH 4.5 is observed, as usually found in titration curves in the absence of urea, thus allowing the direct titration of Glu and Asp residues. It is not possible by the present technique to titrate any group below pH ca. 3 and above pH ca. 10, due to the lack of suitable carrier ampholytes and to a "flooding" phenomenon, with concomitant identical electrophoretic mobility for all protein species, irrespective of their relative pI values and amino acid composition. The "electrophoretic titration curves" thus obtained were well correlated with the overall amino acid composition of the polypeptide chains analyzed.

Electrophoresis, Polyacrylamide Gel↗