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Biomedical subjects

P Hourdille

Publications and source records attributed to P Hourdille.

11 recordsLinked to original sources
PubMed1985

Fibrinogen synthesis by megakaryocyte rich human marrow cell concentrates.

A rapid method is described for the production of a human marrow cell suspension highly enriched in megakaryocytes. These concentrates were incubated with radiolabelled amino-acids, and cell lysates were then analysed for fibrinogen synthesis. Neosynthesized proteins were detected by immunoprecipitation, immuno-affinity chromatography and electrophoresis. Fluorography of the electrophoresis gels showed three radioactive bands corresponding to the three chains of cold fibrinogen. Immunoblotting and autoradiography of bidimensional, nonreduced-reduced electrophoresis gels showed that these three proteins were joined by disulfide bonds in the cell. These results suggest that megakaryocytes synthesize fibrinogen, and imply that platelet fibrinogen is of megakaryocytic origin.

Autoradiography↗
PubMed1985

Distribution of glycoprotein IIb-IIIa complexes in the surface membranes of human platelets and megakaryocytes.

The distribution of glycoprotein (GP) IIb-IIIa complexes in the surface membranes of human platelets and megakaryocytes was investigated by transmission electron microscopy of cells that had been incubated with Fab fragments of a human alloantibody (IgG L) specific for the complex. Binding was visualized by a second antibody conjugated to peroxidase or adsorbed onto gold particles. Initial studies showed that the peroxidase reaction product and the gold particles were to be found at the outer surface of unactivated platelets. The occasional small cluster of particles was present. A positive reaction, more apparent with peroxidase labelling, was also seen in the channels of the platelet open canalicular system. Gold particles were abundant on the outer surface of mature megakaryocytes, and their distribution resembled that on unactivated platelets. As with platelets, peroxidase-labelled antibodies penetrated better, and revealed GP IIb-IIIa in the demarcation membrane system. A double immunofluorescence study, involving Fab fragments of IgG L and rhodamine-conjugated antibodies to factor VIII R:Ag, demonstrated the presence of GP IIb-IIIa in megakaryocyte precursor cells. Our results show that the GP IIb-IIIa complex is present in megakaryocyte membranes and that it appears at the same time as the other platelet antigens.

Antigens, Surface↗
PubMed1982

Protein synthesis in human platelets correlation with platelet size.

Protein synthesis was investigated in human platelets by measuring incorporation of radio actively labelled amino acids into trichloroacetic acid (TCA) precipitable material. Platelet polysomes were characterized by their sedimentation rate in a sucrose gradient. It was confirmed that platelets synthesize proteins in their cytoplasm and that a part of their polysomes are bound to the skeletal framework. A higher level of protein synthesis was found in a population of small platelets separated on Ficoll (2%-4%) density gradient. Moreover, small platelets contained more polysomes than larger platelets. These results show that small platelets are more active in protein turnover or de novo synthesis. These findings can be related to peripheral maturation of platelets.

Blood Platelets↗
PubMed1980

Platelet dense bodies loaded with mepacrine. Study in chronic idiopathic thrombocytopenic purpura (ITP).

In 22 cases of chronic ITP, the platelet 5-HT storage organelles were counted by examination of platelets loaded with mepacrine and correlated with the size and volume of the platelets. Statistical analysis showed that the mean volume and the number of granules increased in ITP without increase in the mean number of granules per unit volume. A strong correlation was found between platelet long diameter and number of dense bodies in controls (44 healthy subjects) (r = 0.94; y = 2.826 x - 0.699) and in ITP (r = 0.92; y = 2.587 x + 0.06). This study demonstrated in chronic ITP the presence both of platelets without granules and others rich in granules. The anomalies were present no matter what the count of platelets and did not change the mean values for granules and for ADP in most cases. Most platelets remain morphologically normal.

Adenosine Diphosphate↗