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Biomedical subjects

Y Beuzard

Publications and source records attributed to Y Beuzard.

At least 127 records · Page 7Linked to original sources
PubMed1980

A gamma and G gamma globin chain synthesis in BFU-E colonies from adult, newborn, and fetal subjects and from thalassemic patients.

The G gamma and A gamma content of Hb F produced in cultures of BFU-Es from the blood of normal fetuses, neonates, and adults was determined. The results show that erythroid progenitors produce A gamma and G gamma chains in a ratio characteristic of their ontogenic stage. The analysis of the G gamma/A gamma ratio in culture of BRU-Es from thalassemic patients showed a marked heterogeneity, resembling that observed in freshly drawn cells. These results afford evidence that the type of gamma chain produced is programmed at the level of early erythroid progenitors.

Adult↗
PubMed1980

Prenatal diagnosis of hemoglobinopathies: comparison of the results obtained by isoelectric focusing of hemoglobins and by chromatography of radioactive globin chains.

Isoelectric focusing (IEF) of hemoglobin was compared to the classical chromatography of labeled globin chains for 22 antenatal diagnoses of hemoglobinopathies: 11 for beta thalassemia, and 11 for sickle cell disease. In all cases, the two methods gave identical results. The diagnosis was confirmed after birth or abortion. Three fetuses homozygous for beta thalassemia and one homozygous for sickle cell disease exhibited no Hb A by IEF, in contrast to normal fetuses or those heterozygous for one of the two hemoglobinopathies. In addition, blood samples obtained in other centers after abortion of 22 fetuses homozygous for beta + or beta 0 thalassemia exhibited no Hb A when analyzed by IEF. When Hb A was present, the respective proportions of Hb A and acetylated Hb F were determined by densitometry of the IEF gel. The Hb A/acetylated Hb F ratio obtained by IEF correlated well with the beta A/gamma ratio of globin chain synthesis, IEF requires 0.1 mg of unlabeled hemoglobin. It is performed in 90 min and several samples can be analyzed simultaneously. If present, maternal contamination of fetal blood must be eliminated by selective lysis of maternal (RBC) using the Orskov reaction. Improvements in this method to obtain suitable samples for IEF analysis are described.

Anemia, Sickle Cell↗
PubMed1980

Cord blood screening for hemoglobin abnormalities by thin layer isoelectric focusing.

Hemoglobin variants can be successfully identified in cord blood samples. The methods most commonly used include cellulose acetate (CAC) and citrate agar (CAG) electrophoresis. Recently thin layer isoelectric focusing (TLIF) has been shown to be an excellent method for identifying hemoglobin variants. To determine the applicability of TLIF for cord blood screening, we compared the results of 835 samples obtained by TLIF with that obtained by CAC, CAG, and the combination of both CAC and CAG. In 100 of these samples we detected an abnormal hemoglobin pattern using TLIF. In contrast, we detected only 80 abnormal samples by CAC, 70 by CAG, and 80 by using the combination of CAC and CAG. Due to the increased resolution provided by TLIF, we correctly diagnosed two sickle cell trait samples by TLIF that were incorrectly suspected to be homozygous for sickle cell disease by CAC and CAG. We identified 41 samples containing Bart's hemoglobin by TLIF in contrast to only 21 using CAC and 14 using CAG. The time and cost of TLIF was comparable to that using the combination of both methods. We, therefore, conclude that TLIF is the method of choice for cord blood screening.

Anemia, Sickle Cell↗
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↗
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

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↗
PubMed1978

Beta thalassemia with reticulocytopenia: clinical, biochemical, and ultrastructural studies.

An unusual form of beta thalassemia is described in two children of unrelated families. Its main features are a severe anaemia with a low reticulocyte count associated with an erythroblastic hyperplasia; these characteristics indicate a completely ineffective erythropoiesis. The results of the study of haemoglobin synthesis performed on the bone marrow in vitro showed a greater imbalance in chain synthesis than that typically found in Cooley's anaemia. Ultrastructural studies revealed, in erythroblasts, all the features observed in Cooley's anaemia, although these features were more widely encountered. In addition, two peculiar findings were noted: (1) many inclusion bodies, which were partially or totally surrounded by smooth membranes, and which may indicate an autophagic phenomenon; and (2) a spongy appearance of the chromatin in rare erythroblasts of one of the two patients which resembled that found in congenital dyserythropoietic anaemia type I. These findings suggest that the great imbalance in the synthesis of the haemoglobin chain is responsible for the presence of an increased number of inclusion bodies and results in the death of nearly all the late erythroblasts. Furthermore, the present results point out the need for further study of the synthesis of the globin chains in atypical congenital dyserythropoietic anaemias.

Blood Cell Count↗