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Biomedical subjects

H Wajcman

Publications and source records attributed to H Wajcman.

At least 163 records · Page 9Linked to original sources
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

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

[Glycosylated hemoglobin: résults of 550 cases (author's transl)].

A selective estimation of glycosylated hemoglobin, HbA1C, exclusive of other minor components, is propably one of the best available tests. Such an automated method is proposed, which was experimented in 550 cases. It demonstrates a quite narrow gaussian distribution in controls. In contrast, a large dispersion is observed among long term diabetics, most of them with ocular complications with only a minority of results in the normal range. This is still more evident in case of juvenile diabetes.

Chromatography↗
PubMed1979

Quantitation of hemoglobin A1c: a rapid, automated precision-chromatography technique.

Hemoglobin A1c is increased in patients with diabetes mellitus and its level reflects the status of blood glucose equilibrium over a period of several weeks. The practical use of its estimation was hampered by technical difficulties in investigating large series of samples. In order to apply this examination for routine purposes we describe in this paper acceleration and full automatization of the original chromatographic method allowing quantitation of hemoglobin A1c in 45 min.

Autoanalysis↗
PubMed1979

Structural bases of the inhibitory effects of hemoglobin F and hemoglobin A2 on the polymerization of hemoglobin S.

We have previously found that the inhibitory effect of hemoglobin F (Hb F) on the polymerization of Hb S proceeds via the formation of asymmetrical hybrid tetramers of the type alpha2betasgamma. Examination of the gelling properties of binary mixtures of Hb S and several Hb variants now shows that, among the gamma chain amino acid residues that differ from those of the beta chain, residues gamma80 (EF4) and gamma87 (F3) are at least partly responsible for this inhibition. Furthermore, we find that mixing Hb A2(alpha2delta2) with Hb S strongly inhibits gelling to an extent similar to that seen with Hb S/Hb F mixtures; this inhibition is attributable to amino acid differences between the delta and beta chain sequences at positions delta22 (B4) and delta87 (F3). Therefore, residues 22, 80, and 87 of the beta chain appear to be involved in intermolecular contact sites that stabilize the deoxy Hb S polymers.

Amino Acid Sequence↗
PubMed1979

[Hemoglobin J Amiens beta 17 (A 14) Lys replaced by Asn. Coincidence of a functionally silent new abnormal hemoglobin and a polycythemia vera (author's transl)].

A new abnormal hemoglobin, Hb J Amiens beta 17 (A 14) Lys replaced by Asn, has been discovered during the exploration of a recent polycythemia in a 65-year-old patient of Spanish extraction. Oxygen affinity of washed red blood cells was found to be normal at pH 7.13 (P 50 = 30.0 mmHg, N = 29.5 +/- 1). Cooperativity is unchanged, and no instability was detected. From this study, it is concluded that there is no relation between this functionally silent hemoglobin and the polycythemia. In fact, the recent appearance of the polycythemia, the involvement of the other blood cell lines, particularly the thrombocytosis, the high score of leukocyte alkaline phosphatases, and the results of the bone marrow biopsy led to the diagnosis of polycythemia vera.

Aged↗
PubMed1979

[Hemoglobin G Coushatta (beta 22 (B4) glu leads to ala) in Algeria: an homozygous case].

In this paper, we report the first observation of Hb G Coushatta (beta 22 (B4) Glu leads to Ala) in North Africa. An homozygous case was discovered and studied. The structural abnormality was characterized by using S. aureus protease. The analytical methods capable of distinguishing these hemoglobins from D Punjab, D Ouled Rabah and D Iran which have similar hemoglobin electrophoretic mobilities will be discussed.

Adolescent↗
PubMed1978

[Hemoglobin Pyrgos beta 83 (EF 7) Gly leads to Asp in a Malian: structural identification and functional properties (author's transl)].

The second observation of hemoglobin Pyrogos is reported. This abnormality was initially described in a Greek family, in our case it concerns an African negro originating from the Republic of Mali. The abnormal hemoglobin was without clinical or hematological consequences. The structural defect is a substitution of an Asp for a Gly in the immediate vicinity of lysine beta 82. This leads to a large inhibition of the corresponding tryptic cleavage and therefore to difficulties in the determination of the mutation. A second feature is a slight modification occurring near one of the 2.3 DPG binding site. As a consequence, the regulatory effect of this organic phosphate is smaller in the purified and stripped component than on hemoglobin A.

Amino Acid Sequence↗