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Biomedical subjects

J Breton-Gorius

Publications and source records attributed to J Breton-Gorius.

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

Cellular regulation of i and I antigen expressions in human erythroblasts grown in vitro.

In order to study the cellular regulation of i and I antigen expressions n erythroid cells, burst-forming-unit erythroids were grown in methylcellulose from the blood of normal human adults. Erythroid colonies were harvested on days 9, 11 or 14 of culture. Individual colonies or pooled colonies were subsequently cytocentrifuged and then i or I antigens were studied by immunofluorescence using a monoclonal anti-i or I antibody. Labelled cells were firstly located, their erythroid origin and their stage of maturation were subsequently ascertained after May-Grünwald-Giemsa staining. This approach shows that: (1) a marked heterogeneity occurred from one colony to another, most of the colonies being i-negative while the others contained a mixed population composed by a minority of i-positive erythroid cells; (2) the proportion of both i colonies and i cells decreased with the aging of culture; (3) i antigen was preferentially expressed on immature erythroblasts; however, immaturity per se was not sufficient to determine i expression; (4) I antigen expression was also related to the process of erythroid maturation but in an inverse way; its expression was higher in mature erythroblasts than in immature ones.

Adult↗
PubMed1981

Embryonic and fetal hemoglobin synthesis in K562 cell line.

K562 cell line was grown in liquid suspension and in plasma clot cultures. Morphological studies revealed the presence of a minority of cells, which were identified as erythroblasts. However, the majority of the cells remained unidentified. Biochemical studies confirmed the synthesis of hemoglobin by K562 cells. The pattern of hemoglobin (Hb) production was of the embryonic type, with the presence of small amount of fetal Hb. The addition of several inducers, like Epo and butyrate, was unable to modify the pattern of Hb production of K562. In contrast, the addition of hemin increased the synthesis of Hb and stimulated the synthesis of fetal Hb and probably adult Hb.

Butyrates↗
PubMed1981

Gray platelet syndrome: alpha-granule deficiency. Its influence on platelet function.

The ultrastructure, cytochemistry, biochemistry, and functions of platelets from two patients with the familial gray platelet syndrome are described. Ultrastructural studies showed a lack of alpha-granules in the megakaryocytes in the vicinity of a marrow myelofibrosis and/or in platelets. A normal number of mitochondria and a slight increase of dense bodies was confirmed by labeling the whole patient with mepacrine. Platelet peroxidase (in the dense tubular system) and catalase-positive granules (revealed by the cytochemistry) were present. Platelets from both patients had severe deficiency of beta TG either after tritonization (less than 4% of normal) or thrombin treatment (less than 15% of normal), and the plasma beta TG levels were slightly increased. Functional studies of these platelets showed an uptake of [14C]5HT inhibited by reserpine similar to that in the control platelets. Thromboxane formation was within normal limits in the presence of arachidonic acid, ADP, collagen, or ionophore A23187, indicating that (1) the cyclooxygenase/thromboxane synthetase systems were not altered and (2) the phospholipase activities were not impaired. Although the platelet adhesion to prepolymerized fibrillar type III collagen and the ADP-, arachidonic acid-, and ionophore A23187-mediated aggregations were apparently normal, in every case the release of [14C]5HT was either at the low side of the normal range or decreased. This abnormality was increased when collagen or thrombin was added to either PRP or washed platelets from both patients, where at the same time, the aggregation and the release were markedly reduced. The results suggest that alpha-granules or their content has an influence on not only the platelet aggregation but also the dense bodies involved in the [14C]5HT release reaction.

Adolescent↗
PubMed1981

Heterogeneity in the cellular commitment of a human leukemic cell line: K 562.

The cellular origin of the K 562 cell line, established from a patient in the blast crisis of chronic myeloid leukemia has been investigated. In agreement with previous reports, an erythroid differentiation was observed. A minority of immature, but hemoglobinized erythroblasts were identified both by electron microscopy and by immunofluorescence using an antibody to gamma-globin chains. Embryonic and fetal hemoglobin (Hb) were synthesized. Hemin increased the number of erythroblasts as well as the absolute amount of Hb synthesized: the Hb pattern was also significantly modified. By cytochemical ultrastructural detection of peroxidase activity (PA), a weak PA, distinct from granulocytic peroxidases, was found exclusively in the nuclear envelope and rough endoplasmic reticulum in a small number proportion of cells. In its localization this PA resembled that of normal and leukemic promegakaryoblasts. The addition of sodium butyrate or dimethylformamide markedly increased the number of these cells (up to 30%) but did not modify their cytoplasmic maturation. No modification of Hb synthesis was observed. Cloning of the K 562 line revealed a marked heterogeneity from one clone to another in Hb production, in the phenotype of Hb synthesis, and in the inducibility by butyrate or dimethylformamide. An inverse relationship between the number of cells with PA and Hb production was found in the different clones. Recloning some of these primary clones resulted in secondary clones, which displayed properties similar to those from which they had originated. All attempts to obtain granulocytic differentiation by addition of different inducers failed. These results clearly indicate that the K 562 cell line arises from the proliferation of bipotent stem cells, these cells possessing variable capacities of differentiation toward erythroid and presumably megakaryocytic cell lineages.

Cell Line↗
PubMed1981

Beta-thalassemia and sickle cell disease in culture of early erythroid precursors: hemoglobin synthesis and ultrastructural study.

Hemoglobin synthesis was studied in culture of early erythroid precursors (BFU-E) from the blood of nine patients exhibiting sickle cell anemia and of 14 with various types of beta-thalassemia. The results concerning gamma gene expression and plating efficiency in heterozygotes for sickle cell anemia were similar to those of normal adults (gamma/alpha = 0.05; 65 BFU-E colonies/10(6) plated cells) while, in contrast, homozygotes for sickle cell disease exhibited average values higher than the controls (gamma/alpha = 0.18; 80 BFU-E colonies/10(6) plated cells). However, the results were very heterogeneous from one subject to another. In heterozygotes for beta-thalassemia, gamma gene expression and plating efficiency were both slightly higher than those for normal individuals (gamma/alpha = 0.095; 129 BFU-E colonies/10(6) plated cells). In patients homozygous for beta-thalassemia, a marked increase in plating efficiency and gamma-chain synthesis was constantly observed (gamma/alpha = 0.41; 221 BFU-E colonies/10(6) plated cells). The high proportion of gamma chain synthesis was not related to a positive selection of F cells, since the gamma/alpha ratio remained constant during the in vitro erythroid maturation. Furthermore, a major increase in free alpha chain proteolysis can be ruled out, since the beta/alpha ratio was of the same order of magnitude in culture and in freshly drawn cells. Thus, the increased Hb F synthesis in vitro was the consequence of a true stimulation of gamma gene expression, which permitted partial correction of the globin chain imbalance. Ultrastructural studies in two homozygotes for beta-thalassemia showed a marked decrease in the abnormalities of the erythroblasts derived from erythroid precursors in vitro in comparison to those from fresh bone marrow samples. In particular, Heinz bodies were much less numerous and a high frequency of mature erythroblasts and reticulocytes was observed in culture. These results support the view that, in sickle cell anemia and beta-thalassemia, a high potential for gamma gene expression exists and can be expressed in culture.

Anemia, Sickle Cell↗
PubMed1981

Constitutional thrombocytopathy with subnormal response to thromboxane A2.

A new type of congenital platelet dysfunction was found in a young woman presenting a life-long bleeding disorder. The known types of thrombopathia and von Willebrand's disease were excluded by appropriate investigations. The platelets were morphologically normal, underwent normal shape change and contraction and synthesized thromboxane A2 (TXA2) normally. The release reaction was abnormal and the aggregation response to ADP, adrenalin, collagen, thrombin, sodium arachidonate and vasopressin was depressed due to decreased sensitivity of the platelets to prostaglandin endoperoxides and TXA2. Platelet cAMP content was increased.

Adolescent↗
PubMed1981

Defective alpha-granule production in megakaryocytes from gray platelet syndrome: ultrastructural studies of bone marrow cells and megakaryocytes growing in culture from blood precursors.

The ultrastructure and cytochemistry of megakaryocytes from two patients with a familial gray platelet syndrome are described. Although the Golgi zones appeared normally developed, the megakaryocytes lacked alpha-granules. Catalase-containing particles were normal in number. In immature megakaryocytes, granules measuring from 0.05-0.1 mu and having an electron-dense core occurred in the Golgi area. These granules, which are considered as the precursors of alpha-granules in normal megakaryocytes, appeared unable to mature, and their number decreased with the megakaryocyte maturation. The presence of dense material in distended demarcation membranes and/or vacuoles suggested that their content was discharged. It is suggested that myelofibrosis present in the bone marrow from these two patients may be related to the possible excretion of a polypeptide growth factor normally contained in the alpha-granules. Megakaryocytes grown by the plasma clot procedure from blood precursors isolated from the two patients also did not exhibit alpha-granules, which were replaced by vacuoles. Our findings suggest that the lack of alpha-granules in gray platelets may be related to a defective megakaryocyte-committed cell, and evidence is presented which suggests that the precursors of alpha-granules are produced but that their contents are then lost.

Blood Platelets↗
PubMed1980

Studies of marmoset megakaryocytopoiesis in vitro.

Liquid culture of the mononuclear fraction of the blood of marmosets without any added stimulator resulted in the appearance of megakaryocytes. These cells could not be identified by light microscopy or by indirect immunofluorescence using antiplatelet antiserum. Ultrastructural identification was made using platelet peroxidase. Some megakaryocytes demonstrated sparse but detectable demarcation membranes, early granule formation, and platelet formation. The results indicate that marmoset megakaryocytic progenitor cells circulate and can begin to differentiate in vitro, although unstimulated liquid culture conditions do not promote the development of the usual light-microscopic features of differentiation.

Animals↗
PubMed1980

Congenital dyserythropoietic anaemia type I: absence of clonal expression in the nuclear abnormalities of cultured erythroblasts.

Erythroid colonies derived from the circulating early erythroid precursor (BFU-E) of a patient with congenital dyserythropoietic anaemia type I (CDA I) have been grown in plasma clot and studied by electron microscopy. The number of circulating BFU-E was in the normal range with a roughly normal appearance at the light microscopic level. However, investigation of individual colonies by electron microscopy has always shown a mixture of normal and abnormal erythroblasts exhibiting the typical nuclear aberrations found in vivo. The proportion of normal erythroblasts varied from one colony to another. After the release of the cells from the clot in order to permit new cellular interactions, macrophages were observed to phagocytose abnormal erythroblasts but also a few erythroblasts with normal nuclei. These findings demonstrate that CDA I is a disorder which results from a defective erythroid stem cell but that the progeny of each BFU-E may vary considerably in the extent to which they express the morphological defects. Based on studies of cultures of BFU-E, similar conclusions were previously made for CDA II.

Adult↗
PubMed1980

Phagocytosis of neutrophil polymorphonuclears by macrophages in human bone marrow: importance in granulopoiesis.

The cytological and electron-microscopic appearance of aneutrophil phagocytosis by macrophages in normal human bone marrow is described. This feature can be observed in every normal bone marrow and is especially frequent in autoimmune disease. Bone marrrow phagocytosis of polymorphonuclear neutrophils seems to be a physiological process resulting from the random egress of neutrophils from bone marrow to blood.

Bone Marrow↗
PubMed1980

Lactoferrin deficiency as a consequence of a lack of specific granules in neutrophils from a patient with recurrent infections. Detection by immunoperoxidase staining for lactoferrin and cytochemical electron microscopy.

Neutrophils from a boy suffering from recurrent infections were found to be totally deficient in specific granules when studied by electron microscopy. In contrast, myeloperoxidase-containing azurophil granules were increased in number. This deficiency of specific granules could be detected at the light-microscopic level using an immunocytochemical technique to demonstrate the absence of lactoferrin. Neutrophils also exhibited abnormal nuclear segmentation, nuclear clefts, an abnormally weak cytochemical reaction for alkaline phosphatase, and an increased number of mitochondria and ribosomes. Some granulocytic precursors were abnormal, and many of these cells were phagocytosed by macrophages in the bone marrow. Despite these multiple abnormalities and the history of severe pyogenic infection, the in vitro bactericidal capacity of the neutrophils was within normal limits, and normal degranulation of azurophil granules occurred following phagocytosis. The precise mechanism by which the deficiency of specific granules in this patient led to an enhanced in vivo susceptibility to infection therefore remains obscure. However, attention is drawn to the fact that in three previously described cases of specific granule deficiency a history of recurrent infections was present.

Bacterial Infections↗