Search PubMed⌕ Search

Biomedical subjects

H Rochant

Publications and source records attributed to H Rochant.

At least 91 records · Page 5Linked to original sources
PubMed1981

Genetic regulation of gamma gene expression: study of the interaction of beta-thalassemia with heterocellular HPFH.

A family has been observed which a gene for heterocellular hereditary persistence of fetal hemoglobin (HPFH), probably identical to that previously described as Swiss type HPFH, has been inherited together with beta-thalassemia. The interaction of these two genes resulted in beta-thalassemia heterozygotes with unusually high levels of fetal hemoglobin (3.6-6.15), heterogeneously distributed. Globin synthesis studies showed a similar degree of chain imbalance in the heterocellular HPFH-beta thalassemia compound heterozygotes and in the heterozygous beta-thalassemia member of the family. On the basis of the pattern of genetic transmission of these two characters it can be concluded that the HPFH determinant does not behave as an allele of the gamma beta delta complex.

Adolescent↗
PubMed1981

Change in i-antigen expression of erythrocytes during in vivo aging.

The expression of i-antigen during the in vivo aging of erythrocytes from normal subjects and beta-thalassemic patients was investigated by immunofluorescence labeling and by immunoagglutination. The results showed that the expression of i-antigenic determinants inversely related to the aging of RBCs. This phenomenon could be either the result of a progressive loss of i-antigenic structures or the consequence of i to I transformation occurring during RBCs aging in vivo.

Anemia, Hemolytic, Autoimmune↗
PubMed1981

F-cells are preferentially distributed among high density erythrocytes.

Red blood cells from normal subjects and subjects with heterocellular hereditary persistence of fatal haemoglobin and beta-thalassaemia were fractionated according to density by centrifugation on a discontinuous gradient of Stractan II. F-cells were studied by immunofluorescence and their proportion was evaluated in each separated population. This approach has permitted to show that F-cells were preferentially distributed among high density erythrocytes. This phenomenon reflects a peculiar characteristic of F-cells.

Animals↗
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↗
PubMed1980

[Thrombocytopenic thrombotic purpura in adults. 10 cases (author's transl)].

Thrombocytopenic thrombotic purpura is a rare condition of controverted pathophysiology. The authors have observed and treated 10 cases between 1974 and 1979. The clinical features were uniform: haemolytic anaemia with schistocytosis (10/10), thrombopenia (10/10), fever (9/10), varying neurological disorders (9/10) which required assisted ventilation in 7 cases. Renal insufficiency was found in 7 patients, but associated with renal lesions only one and never interfered with the course of the disease. All patients received corticosteroids in high dosage and anti-platelet aggregation drugs. That treatment alone cured 3 patients. In addition, 5 patients underwent plasmapheresis, which seemed to be very effective in 2 cases. Five patients died, 3 of whom despite corticosteroids, anti-aggregants and plasmapheresis. Thus, none of these treatments seems to be effective in all cases, and prospective multicentre therapeutic trials are probably required.

Adult↗
PubMed1980

[Cellular regulation of the expression of i and I antigens during the in vitro differentiation of BFU-E].

Burst forming units (BFU-E) from the blood of eight normal adults were grown in methylcellulose culture. Follow up of i and I antigens detected by an indirect immunofluorescence technique from the 9th to the 14th day of culture revealed that i antigen expression diminished while maturation proceeded. On the contrary 1 antigen expression increased meanwhile. Nevertheless, in addition to this maturation process, expression of i antigen must be determined by a regulatory mechanism operating during erythroid stem cell differentiation since a large proportion of immature erythroblasts at the 10th day of culture do not express i antigen.

Adult↗
PubMed1980

Disappearance of Hb F and i antigen during the first year of life.

In order to investigate whether a common control mechanism is involved in the diminution of i antigen expression and that of Hb F content in human erythrocytes during the postnatal period, we compared changes in 72 normal infants aged from 0 to 12 months. The proportion of hemoglobins (Hb F, Hb A, Hb A2) and the quantitation of "i" antigen were determined on the total population of red blood cells. In addition, the percentage of individual cells containing Hb F or "i" antigen or both (F cells, "i" cells, and F + "i" cells) were evaluated by using a rhodamine-conjugated anti-Hb F and a fluorescein conjugated anti-system on the same smear preparation. The results provided by the two most sensitive techniques (F cell counting and "i agglutinability) indicated that the curves of disappearance of Hb F and "i" antigen along the 12 first months after birth were identical. A strong correlation (r = 0.97, P < 0.0001) existed between the percentage of F cells and "i" antigen expression. In addition, the progressive increase in Hb A2 concentration was inversely correlated firstly with the proportion of Hb F and second with the expression of the "i" antigen. These results suggest that the switch from fetal to adult hemoglobin and the transformation of "i" antigen expression occurring during the first year following birth are governed by a common control mechanism.

Aging↗
PubMed1980

Fetal hemoglobin synthesis in culture of early erythroid precursors (BFU-E) from the blood of normal adults.

BFU-E from the blood of 14 normal adults have been grown by the plasma clot technique. The hemoglobins synthesized in burst colonies were purified from other proteins by affinity chromatography on Sepharose-haptoglobin. The radioactivity incorporated in the globin chains was estimated by CM-cellulose chromatography in urea. The number of bursts scored at the 14th day of culture fluctuated between 50-130 (average 86, s: 29) for 10(6) mononuclear plated cells. A constant reactivation of fetal hemoglobin was found (from 1.4% to 11%, mean value 5.8%, s:3.07), but was lower than previously described, mainly because of the highly selective purification of Hb. This reactivation of fetal hemoglobin was not dependent upon the concentration of erythropoietin (from 1 U/ml to 6 U/ml) nor on the purity of the erythropoietin preparations (from 6 U/mg of protein to 70 000U/mg of protein). In addition, the same subject exhibited a constant proportion of Hb F synthesized in culture over a period of time up to 6 months. A positive correlation exists between the proportion of Hb F in culture and that of F cells present in the blood, with the exception of two subjects. Such findings suggest that Hb F in culture is a characteristic of each individual and that this reactivation often represents an amplification of the Hb F synthesis in vivo.

Adult↗
PubMed1980

Acute non myeloid leukaemia in adults. Prognostic factors in 92 patients.

An analysis of prognostic factors was performed on a series of 92 adult patients with acute non-myeloid leukaemia (ANML). Four factors were shown to be correlated with a poor short-term prognosis: (1) Neuropathy involving a single cranial nerve (numbness of the chin) as a presenting feature. (2) A low percentage blast cell infiltration of bone marrow (less than 55%). (3) Cytological L2 type or L3 type of cells according to FAB classification proposals. (4) Increased age. Two factors were shown to be correlated with a poor long-term prognosis: 1) A high level of circulating blast cells; 2) A high tumour burden, as in childhood ANML. These two long-term prognostic factors were interrelated. In addition, our results suggested that myelofibrosis could be a poor long-term prognosis factor as well.

Acute Disease↗
PubMed1980

Elevated Hb F associated with beta-thalassaemia trait: haemoglobin synthesis in reticulocytes and in blood BFU-E.

The red cells of a patient heterozygous for beta-thalassaemia contained 19% fetal Hb. Study of his family suggested that the proband had inherited the Swiss type of hereditary persistence of fetal Hb (HPFH) from his mother who is not thalassaemic and possessed 1.37% of Hb and 11% F-cells. Studies of globin synthesis showed a similar imbalance in the heterocellular HPFH-beta-thalassaemia compound heterozygotes and in the heterozygous beta-thalassaemic members of the family. Age stratification of the red cells showed a slight enrichment in Hb F and a decreased Hb A2 level in the older cell populations. Hb F production in the BFU-E colonies of the proband was higher than that found in vivo and in other beta-thalassaemic heterozygotes in culture. Study of single erythroid burst colonies showed a marked heterogeneity in Hb F synthesis from one colony to another, while the pool of free alpha-chains remained of similar magnitude. It is suggested that in the proband, the HPFH gene, which is in trans with respect to the beta-thal-gene, increases the size of the F-cell population and its activity is carried on at the expense of the normal beta A gene.

Cells, Cultured↗
PubMed1980

Expression of the blood group I, i, H, and A1 antigens on erythrocyte membranes studied by immunofluorescence.

A double immunofluorescence technique was used to study the expression of I, i, H and A1 antigens on individual erythrocytes of neonates, adult controls and patients with various haematological disorders. I, i and H staining was heterogeneously distributed from cell to cell as was already demonstrated for A1 antigen. i staining occured in 41 to 64% of cord cells (11 to 32% were strongly fluorescent) but only in 0.2 to 2.3% of adult erythrocytes. I staining occurred in 54 to 97.5% of adult erythrocytes but only in 1 to 14% of those of cord blood. Patients' cells tended to mimic a foetal pattern of heterogeneity in that an increase of i stained cells occured associated with a decrease of A1 or H stained cells. It is suggested that the foetal-like red cells observed in patients with haematological disorders result from an expansion of a normal process of differentiation rather than clonal development of abnormal cells.

ABO Blood-Group System↗
PubMed1980

Congenital dyserythropoietic anemia type III. studies on erythroid differentiation of blood erythroid progenitor cells (BFUE) in vitro.

In order to investigate whether the morphological abnormalities observed in congenital dyserythropoietic anemia type III (CDA III) have a cellular or an environmental origin; BFUE from the blood of a patient exhibiting a CDA type III were grown in vitro. The progeny derived from these BFUE were subsequently studied at light and electron microscopic level. Giant multinuclear erythroblasts which represent the most prominent finding of CDA III in bone marrow were also found in culture. Nuclear clefts found in vivo were also observed by electron microscopic studies performed on the erythroblasts growing in vitro. In each erythroid colony, morphologically normal and giant multinuclear erythroblasts were intermingled. This finding indicates that the two populations of erythroblasts derive from the same defective stem cell. The studies by indirect immunofluorescence of i antigen was preferentially expressed in the immature erythroblasts as in culture from normal subjects but not in the giant mature erythroblasts. This finding suggests that the excess of i antigen expression of CDA III in vivo is rather the indirect consequence of a stimulation of erythropoiesis than result of the disease.

Adult↗