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Biomedical subjects

J Rosa

Publications and source records attributed to J Rosa.

At least 181 records · Page 10Linked to original sources
PubMed1979

Fetal to adult hemoglobin switch in cultures of early erythroid precursors from human fetuses and neonates.

Erythroid burst colonies derived from the cord blood of nine neonates and from the blood and liver of three fetuses aborted after 20 weeks of gestation were grown in plasma clot culture. Their quantitative study revealed a higher proportion of burst-forming units (BFU-Es) in cord blood than in cord blood of normal adults. In addition, colony-forming units (CFU-Es) were present in cord blood but absent from adult blood. Study of haemoglobin synthesis in 14-day cultures of cord blood BFU-Es showed a significantly higher degree of Hb A synthesis than was found in reticulocytes from fresh cord blood; this proportion was, however, similar to that expected in vivo about three weeks after birth. These data suggest that the hemoglobin switch is already programmed in most of the early erythroid precursors present in cord blood or full-term neonates and indicate that the differentiation time is probably of the same order of magnitude in vivo and in vitro. The proportion of Hb A and F synthesis in erythroid bursts was not influenced by the concentration of erythropoietin in the range studied--ie, from 0.5 to 12 international units. Low but identical proportions of Hb A synthesis were found both in erythroid cells from liver after two hours of incubation with [3H]-leucine, and in 14-day liver bursts from fetuses aborted at 20 weeks of gestation.

Adult↗
PubMed1979

Hemoglobin Bougardirey-Mali beta 119 (GH2) Gly replaced by Val. An electrophoretically silent variant migrating in isoelectrofocusing as Hb F.

Hemoglobin Bougardirey-Mali was detected by isoelectrofocusing during a screening in a 32 years old African, a native of Mali. This abnormal Hb, representing 35% of the total, exhibited the same pI as that of Hb F. In contrast, it was indistinguishable from Hb A in all the electrophoretic systems tested, and equally by its resistance to alkaline denaturation. Structural studies have shown that the abnormality was localized on the beta chain. A fingerprint of the tryptic digest of the aminoethylated beta chain indicated the absence of the beta T12 b. The presence of an abnormal beta T12 b was suspected in the T14-15 spot, as indicated by the intensity of staining and its amino acid composition. beta T12 b was isolated by chromatography on PA 35. Its sequential analysis by manual Edman-dansyl degradation showed that glycine 119 was replaced by a valine residue. This mutation is localized in a alpha 1 beta 1 contact, which makes the molecules slightly unstable. The clinical consequences of this mutation seem to be minor; similar observations have been reported for the other Hb mutated at the same locus, i.e. Hb Fannin-Lubbock beta 119 Gly leads to Asp.

Adult↗
PubMed1979

Hb A1c: a review on its structure, biosynthesis, clinical significance and methods of assay.

Normal red blood cells contain, in addition to the major hemoglobin (Hb A) some minor fractions as Hb A2 and glycosylated hemoglobins: Hb A1a, Hb A1b, Hb A1c. The study of the glycosylated hemoglobins has been greatly stimulated by the observation that their proportion was increased in diabetes mellitus. This paper sums up the more recent knowledge on the structure of the minor fractions, and mainly on Hb A1c. Biosynthesis of these hemoglobins is also considered. Since the glycosylated hemoglobins has raised a great interest, different techniques were designed for its assay: chemical, chromatographic and immunological techniques and isoelectric focusing. In this paper, these different methods are reviewed and compared.

Animals↗
PubMed1978

The first case of a complete deficiency of diphosphoglycerate mutase in human erythrocytes.

An inherited and complete deficiency of diphosphoglycerate mutase was discovered in the erythrocytes of a 42-yr-old man of French origin whose blood hemoglobin concentration was 19.0 g/dl. Upon physical examination he was normal with the exception of a ruddy cyanosis. The morphology of his erythrocytes was also normal and there was no evidence of hemolysis. The erythrocyte 2,3-diphosphoglycerate level was below 3% of normal values and, as a consequence, the affinity of the cells for oxygen was increased. Diphosphoglycerate mutase activity was undetectable in erythrocytes as was that of diphosphoglycerate phosphatase. The activities of all the other erythrocyte enzymes that were tested were normal except for nomophosphoglycerate mutase which was diminished to 50% of the normal value. The levels of reduced glutathione, ATP, fructose 1,6-diphosphate, and of triose phosphates were elevated, whereas those of glucose 6-phosphate and fructose 6-phosphate were decreased. This report sheds new light on the role of diphosphoglycerate mutase in the metabolism of erythrocytes.

Adult↗
PubMed1978

Hemoglobin Creteil: oxygen transport by erythrocytes. In-vitro and in-vivo studies in a high oxygen-affinity mutant hemoglobin.

Hemoglobin Hb) Creteil alpha2beta(2)89 (F5) Ser leads to Asn is a high oxygen-affinity variant that has a low cooperativity, a decreased Bohr effect, and does not interact with diphosphoglycerate (DPG) (1). This hemoglobin variant was silent by routine electrophoresis. Careful analyses of the oxygen dissociation curves of erythrocytes, determined at varying pH and Pco2 in fresh and DPG-depleted cells, gave extensive information on the abnormal function of the mutant hemoglobin. From the O2 dissociation curves of the erythrocytes of the heterozygous subject it appeared that Hb Creteil is inappropriate for O2 transport to the tissues because it remained completely saturated with O2 at normal physiologic levels of Po2. In-vivo measurements showed that only one half of the total hemoglobin present actually participated in oxygen transport. Polycythemia should therefore be maintained within clinically tolerable limits because it helps to keep arterial Po2 and Pvo2 close to their normal values and thus protects the individual from a permanent increase in blood flow.

Adult↗
PubMed1978

Isoelectric focusing of human hemoglobin: its application to screening, to the characterization of 70 variants, and to the study of modified fractions of normal hemoglobins.

Isoelectric focusing on slabs of acrylamide gel was adapted for the screening of abnormal hemoglobins, the characterization of 70 human variants, and the study of minor fractions of normal hemoglobin. The screening method was as fast and inexpensive as conventional techniques, allowed the simultaneous analysis of some 50 samples of whole blood, and yielded resolution superior to that obtained by other methods with hemolysates. Among the 70 variants, 31 mutants could not be separated from HbS by cellulose acetate electrophoresis. The characterization technique of electrofocusing allowed us to distinguish between most variants. Only one mutant, Hb Galveston, could be confused with HbS. Hb Köln, the most frequent unstable mutant, exhibited a special pattern. HbA1C was separated from HbA. Preliminary results indicate that quantitation of HbA1C by gel scanning is feasible.

Electrophoresis, Cellulose Acetate↗