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Biomedical subjects

P Triadou

Publications and source records attributed to P Triadou.

18 recordsLinked to original sources
PubMed1996

Lack of platelet response to collagen associated with autoantibodies against glycoprotein (GP) Ia/IIa and Ib/IX leading to the discovery of SLE.

An increased bleeding time and a prolonged APTT (activated partial thromboplastin time) observed in a 48-year-old woman led to the discovery of SLE confirmed by immunological tests. Platelet function and analysis of membrane glycoproteins revealed an isolated impaired collagen induced platelet aggregation and allowed the detection of autoantibodies directed against GpIa/IIa and GpIb/IX.

Antigens, CD↗
PubMed1994

Fetal haemoglobin variations following hydroxyurea treatment in patients with cyanotic congenital heart disease.

Haematological features of 64 patients suffering from non operable cyanotic congenital heart disease (CCHD) treated with hydroxyurea (HU) were compared with those of 43 patients suffering from the same disorder who had not yet received this drug. Patients with subclinical renal dysfunction were excluded by measuring plasma creatinine levels. MCV and HbF were higher among patients receiving HU, the increase in MCV being cumulative with HU dosage but the rise in HbF dose independent. HbF response to HU was found to be due to the coordinated increase in F-cell and F-reticulocyte production rather than to a selective survival of F-cells. Absence of a relationship between plasma erythropoietin and HbF levels excluded a dominant role of the former in increasing F-cell production and results determined after doubling the HU dosage or immediately after initiating therapy suggested genetic differences to be responsible for the individual variations in Hb F response. No irreversible toxic effects or malignancies were noted in this series of patients. HU was administered for a relatively long period of time, the mean duration of treatment exceeding 5 years, while the study also included patients below the age of 10 years.

Adolescent↗
PubMed1992

Human platelet aggregation by Yersinia pseudotuberculosis is mediated by invasin.

Plasmid-free strains of Yersinia pseudotuberculosis induce aggregation of human platelets in vitro. It appears that this phenomenon is mediated by invasin (Inv), a 103-kDa outer membrane protein that permits bacteria to penetrate mammalian cells, since (i) an isogenic inv-deficient mutant failed to aggregate platelets compared with the parental strain; (ii) a monoclonal antibody directed against invasin inhibited platelet aggregation; (iii) Inv+ Escherichia coli HB101 promoted platelet aggregation. Platelet receptors for invasin were identified by using a panel of anti-platelet glycoprotein monoclonal antibodies in a bacterial adhesion assay. We found that bacteria bind to platelet membrane glycoproteins Ic and IIa. Electron microscopic study of bacterium-platelet interactions also revealed that bacteria expressing invasin attach to and are phagocytized by thrombocytes, in contrast to inv-deficient bacteria, indicating that these anucleated cells are able to internalize bacteria in vitro after specific interaction with invasin.

Adhesins, Bacterial↗
PubMed1990

Platelet function in sickle cell disease during steady state.

Platelet function was investigated in 37 patients with sickle cell disease during steady state. The measurement of platelet aggregation in whole blood, demonstrating interaction of sickle cells and platelets, showed increased activity in patients compared to controls. In contrast, by classical platelet aggregation in platelet-rich plasma (PRP) we observed decreased platelet aggregation in sickle cell patients. Aggregation of washed platelets appeared identical in patients and controls beta thromboglobulin (beta TG) and platelet factor 4 (PF4) as well as fibrinopeptide A (FPA) plasma levels were increased in patients with sickle cell disease. These results suggest that in sickle cell patients there is in vivo platelet stimulation, which may therefore appear "exhausted" in patients plasma during in vitro studies, and also a possible role of coagulation in the pathophysiology of sickle cell disease as supported by high levels of FPA.

Adenosine Triphosphate↗
PubMed1989

Use of the ferritin/alanine aspartate transaminase ratio as an iron overload marker independent of liver cell damage.

To define an iron overload index independent of liver cell damage, the mean annual levels of alanine aspartate transaminase (ALAT) and serum ferritin and their ratios were determined. Ferritin/ALAT ratio values were compared between two groups of patients with acute or chronic hepatitis without iron overload, and one group of thalassaemic patients with iron overload. The two groups without iron overload exhibited ferritin/ALAT ratio values of 2 and 1.2 respectively; a ratio value higher than 10 was always observed in those patients with iron overload. The ferritin/ALAT ratio is correlated with the degree of iron overload. This ratio increases in regularly-transfused patients without chelation treatment. It generally remains stable or decreases after initiation of iron chelation therapy. The ferritin/ALAT ratio thus appears useful in the follow-up of patients subjected to a long-term transfusional treatment particularly when acute or chronic liver cell damage may interfere with iron overload by increasing serum ferritin values.

Alanine Transaminase↗
PubMed1986

Neocytopheresis: a new approach for the transfusion of patients with thalassaemia major.

At present the treatment of thalassaemia major consists of regular blood transfusions coupled with chelation therapy using deferoxamine. A complementary approach to the problem is the use of blood units enriched with young red cells (neocytes), which reduce the transfusional frequency and thereby diminish the risk of iron overload. Young red cell units were collected from blood from 60 volunteer donors using a cell separator (IBM 2997). Donors' blood was anticoagulated and the young red cell harvesting carried out over 4 h at a constant rotor speed of 500 rpm. Three biological criteria were used to evaluate young red cell quality: the number of reticulocytes, the pyruvate kinase activity and the mean corpuscular volume, all of which show an enrichment of young red cells as compared to standard donor units. The 51Cr young red cell survival in four normal donors and in two splenectomized patients showed an increased red cell half-life compared to the same study performed with standard blood units. Blood consumption was diminished significantly when the two patients were transfused with young red cell units. It must be emphasized that, despite the high cost of this blood product, the efficiency of this transfusion technique, by reducing blood consumption, represents important progress and a hopeful treatment for chronic anaemia.

Blood Donors↗
PubMed1983

Tissue-specific formation of transcription-initiation complexes at the 5' end of the mouse beta major globin gene.

Accurate initiation of transcription in vitro requires, in addition to RNA polymerase II, factors present in soluble extracts of cultured cells. We have developed transcription system in vitro, which permits us to visualize the transcription-initiation complexes on a mouse beta globin restricted fragment from a recombinant beta globin bacteriophage DNA. Using the lambda fragments as internal controls this system has allowed us to assess the specificity of transcription with RNA polymerase II. Comparing extracts from cells and tissues expressing the globin genes (Friend cells, spleen and blood from phenylhydrazine-induced anemic mice) with those which do not (thymus, liver, PCC3 cells), we observed that specific initiation of transcription on the beta globin gene occurs only with soluble extracts from erythroid tissues. This tissue-specific transcription is partially sensitive to alpha-amanitin and occurs at the 5' end of the globin gene.

Amanitins↗
PubMed1983

Alpha-globin loci in homozygous beta-thalassemia intermedia.

Homozygous beta-thalassemia intermediate (TI) differs from thalassemia major (TM) in being less severe clinically. Associated alpha-thalassemia could account for the TI phenotype by reducing the alpha/non-alpha chain imbalance. We have analyzed the alpha loci of 9 TI and 11 TM patients by restriction endonuclease mapping. All the TM and 7 of the TI patients have the normal complement of four alpha-globin genes (alpha alpha/alpha alpha). One TI patient has three alpha-globin genes (alpha alpha/-alpha), and another TI patient has five alpha genes (alpha alpha/alpha alpha alpha).

Adolescent↗
PubMed1982

Tissue-specific binding of total and beta-globin genomic deoxyribonucleic acid to non-histone chromosomal proteins from mouse erythropoietic cells.

The synthesis and DNA binding activity of purified nuclear non-histone proteins from mouse erythroblasts and myoblasts have been compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, affinity chromatography, and protein blotting. The labeled non-histone proteins bound to mouse total DNA clearly differ between erythroid and muscle cell lines, but these differences mainly reflect the qualitative changes observed in their pattern of synthesis. By contrast, a cloned genomic mouse beta-globin DNA fragment binds specifically several proteins (100K, 65K, 50K, 45K, and 34K) from erythropoietic Friend cells and does not bind any protein in the corresponding fraction from myoblasts. The specificity of these DNA protein interactions requires a NaCl concentration of 0.1 M and a low protein/DNA ratio. In these conditions lambda DNA binds the above proteins to only a small extent. During the dimethyl sulfoxide induced terminal differentiation of Friend mouse erythroleukemia (MEL) cells, there is an apparent overall decrease of total as well as globin DNA binding to the nuclear non-histone proteins but not to the histones, whereas no significant qualitative changes are detected.

Animals↗
PubMed1982

[Thalassaemia intermedia. Clinical and laboratory study. Therapeutic suggestions (author's transl)].

The clinical and laboratory criteria which distinguish thalassaemia intermedia (T.I.) from thalassaemia major were analyzed in a series of 30 patients with homozygous beta- thalassaemia, 8 of whom had T.I. The appearance of the first symptoms after the age of 2 years, the moderate spleen enlargement, the haemoglobin levels approaching 8 g/100 ml and the response to moderate transfusions over 1-year observation period were in favour of T.I. Since patients who had transfusions were clinically better than those who had none, it is suggested that T.I. patients should be treated with regular transfusions and iron chelating agents.

Age Factors↗
PubMed1982

[Monitoring and appraisal of the effects of blood transfusion and iron chelation in thalassemia major].

A total of 21 patients with thalassaemia major between 2 and 20-years-old were on a "hypertransfusion" regimen for 1 to 14 year periods. The use of the transfusion quotient (TQ) allowed a precise survey of the blood requirement. In all splenectomized patients the TQ was between 1 and 2; TQ increased and was always greater than 2 when patients became hypersplenic. Of the 21 regularly transfused patients, 12 had iron chelation therapy by continuous subcutaneous desferrioxamine (DF) injection (1 g over 8 to 12 h at home, nightly). The iron balance was negative for 7 patients, equilibrated for 1 and positive for 4 patients. All patients receiving more than injections of DF weekly had a negative balance; the variation of the serum ferritin level correlated with the iron balance (r = 0,77; P less than 0,01). The beneficial effects of the treatment were improvement in social and professional activity, in growth and puberty development and attenuation of the skull and face dysmorphia. Monitoring ferritin is a simple way to estimating the effects of chelation on iron overload.

Adolescent↗
PubMed1981

Identification of transcription initiation sites for bacterial RNA polymerase and eukaryotic RNA polymerase B on the 5' end of the mouse beta-Globin gene.

Using a recombinant phage containing the mouse beta-Globin gene with lambda gtWES bacteriophage DNA, transcription initiation sites for Escherichia coli RNA polymerase and calf thymus RNA polymerase B were mapped at the 5' and 3' ends of the mouse beta-Globin gene. The bacterial enzyme was capable of initiating RNA synthesis at the 3' end site located at about 700 residues from the 3' end of the beta-Globin restriction enzyme map. Initiation at this site was more efficient than initiation at the known early lambda promotors (PL, PR). Calf thymus RNA polymerase B initiated transcription at the same sites as the bacterial enzyme but in this case maximum efficiency was at the 5' end site as compared to the 3' end site. Initiation of transcription occurs in the region of the d(T-A-T-A-A) sequence. Initiation efficiency at the 5' end site, as probed by the maximum rate of transcription, was shown to depend partly upon the presence of the adjacent sequences upstream and downstream of the 5' initiation site.

Base Sequence↗
PubMedDate not supplied

[Some historic milestones of clinical haematology].

Microscopy, cell staining methods and tests for characterization of coagulation factor deficiencies are the landmarks of hematology at the beginning. Direct access to bone marrow, automatization, development of in vitro culture systems, monoclonal antibodies, biochemistry of proteins and nucleic acids were used to build today conception of the blood. Definitions of stem cells, growth factors, chromosomal translocations in leukemias and coagulation cascade represent the various aspects of the complex scientific object that the blood became.

Blood Coagulation↗