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Biomedical subjects

J Riou

Publications and source records attributed to J Riou.

70 records · Page 4Linked 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

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↗
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↗
PubMed1977

[Hepatic and renal desamidinases in swine].

By cellulose acetate electrophoresis we have confirmed the presence of two desamidinasic fractions in aqueous extracts of acetone powder from pig liver. Pig kidney extracts have been partially purified by thermal denaturation and chromatography on Sephadex G-200 and D.E.A.E. Sephadex A-50. Michaelis constants of the two eluted arginasic fractions have been determined.

Animals↗
PubMedDate not supplied

Short insertion in a hemoglobin chain: Hb Esch, an unstable alpha1 variant with duplication of the sequence Ala65-Leu-Thr-Asn68.

Hemoglobin (Hb) Esch, is an alpha1 variant, expressed at less than 5%, resulting from the duplication of the 12 nucleotides corresponding to CD65 through 68. The effect of this insertion is the repetition of the sequence Ala-Leu-Thr-Asn, which corresponds to the last turn of helix E. In this variant the presence of a one-turn elongated helix E causes instability and increased ligand affinity. Hb Esch was characterized by DNA sequencing and confirmed by electrospray mass spectrometry. Functional studies were performed by flash photolysis measurements on a fraction isolated by flatbed isoelectric focusing, which was enriched in the abnormal hemoglobin. Similar to other alpha chain variants due to short insertion (or deletion), Hb Esch probably results from a slipped mispairing mechanism. The stability of such modified proteins depends upon the region which is added or deleted and usually is more stable when involving a flexible loop or complete helix turn(s) near by.

Adult↗
PubMedDate not supplied

Determination of Hb F levels: the routine methods.

The two classical methods used to determine the level of Hb F in a hemolysate are herein described. Measurement of this hemoglobin fraction by resistance to alkali denaturation was the first technique introduced; it is today largely replaced by ion exchange high performance liquid chromatography. The limits, pitfalls, and advantages of the two methods are discussed.

Alkalies↗