Search PubMed⌕ Search

Biomedical subjects

M Dechavanne

Publications and source records attributed to M Dechavanne.

At least 109 records · Page 6Linked to original sources
PubMed1982

Tryptic peptide map analysis of the major human blood platelet membrane glycoproteins separated by two-dimensional polyacrylamide gel electrophoresis.

Washed platelets were surface-labelled by lactoperoxidase catalyzed iodination and either the platelets or membranes were solubilized in detergent and applied to a wheat germ agglutinin-Sepharose column and a Lens culinaris lectin Sepharose column coupled sequentially. The glycoproteins eluted from the lectin columns were separated by two-dimensional gel electrophoresis. Alternatively, labelled whole platelets or membranes were solubilized and then directly separated by two-dimensional polyacrylamide gel electrophoresis. Spots corresponding to specific glycoproteins identified by apparent isoelectric point (pI), apparent molecular weight (Mr), staining and labelling characteristics were cut from the gels and analyzed by tryptic peptide mapping. The maps of the individual glycoproteins(GP) Ia, Ib, IIa, IIb, GP4-4.5 132-135, IIIa, IIIb and IIIc were all different. Glycoproteins with the same Mr but different pI were distinct with the exception of regions of GP Ib. There were minor differences in the maps of glycoproteins separated in the reduced or non-reduced state. Tryptic peptide maps provide a valuable additional parameter for the identification and characterization of platelet glycoproteins.

Blood Platelets↗
PubMed1982

Simultaneous enzymo-immunologic assays of platelet associated IgG, IgM and C3. A useful tool in assessment of immune thrombocytopenias.

A solid phase enzymo-immunologic assay (EIA) has been developed to measure platelet associated (PA) IgG, IgM and C3. Washed platelets are mixed with a goat anti-IgG (IgM or C3) antiserum and then incubated in serum coated polystyrene plates. There is an inverse relationship between the level of PA IgG (IgM or C3) and the amount of goat antibodies binding to the IgG (IgM or C3) coating the plates. These goat antibodies are detected by addition of a phosphatase-labelled sheep anti-goat immunoglobulins antibody followed by a substrate giving a colour reaction. Using this technique, platelets from normal donors gave values of 2.04 +/- 1.10 fg IgG/platelet (mean +/- SD), 8.66 +/- 2.61 x 10(-16) g IgM/platelet and 5.67 +/- 2.63 x 10(-16) g C3/platelet. In 35 thrombocytopenic ITP patients we observed an increased level of PA IgG in 25, of PA IgM in 24 and of PA C3 in 23, and all of them had at least an increase of one of the 3 components. In 10 ITP patients in remission, 2 had an increased level of PA IgG while PA IgM and C3 values were normal in all. On the other hand, 2 non thrombocytopenic patients with systemic lupus erythematosus had an increased level of PA IgM. Compared to the standard antiglobulin consumption assay (ACA), the EIA was simpler to perform and more sensitive.

Blood Platelets↗
PubMed1982

Characterization of the platelet membrane glycoprotein abnormalities in Bernard-Soulier syndrome and comparison with normal by surface-labeling techniques and high-resolution two-dimensional gel electrophoresis.

The platelets from three patients with Bernard-Soulier syndrome have been analyzed by surface-labeling coupled with two-dimensional gel electrophoresis and compared with normals. As well as the previously described absence or deficiency in glycoprotein (GP) Ib(alpha) it could be shown that GP Ib beta and an additional low molecular weight glycoprotein GP17 were not detectable using carbohydrate-labeling methods or deficient to the same extent as the GPIb alpha subunit. In addition, the thrombin cleavable glycoprotein could not be detected using carbohydrate-labeling methods in two patients and was deficient in a third. This finding was confirmed in a fourth patient by one-dimensional gel electrophoresis. Thus, the changes in the membrane of Bernard-Soulier platelets are more complex than previously thought.

Adolescent↗
PubMed1981

Glycoproteins of platelet membranes from Glanzmann's thrombasthenia. A comparison with normal using carbohydrate-specific or protein-specific labelling techniques and high-resolution two-dimensional gel electrophoresis.

Platelets from Glanzmann's thrombasthenia patients and from normal donor were surface labeled by techniques specific for sugars (terminal sialic acid, penultimate galactose/N-acetylgalactosamine) and proteins (tyrosine-histidine residues). These labelled platelets were solubilized in sodium dodecyl sulphate and separated on a two-dimensional electrophoretic system [O'Farrell. P. H. (1975) J. Biol. Chem. 250, 4007--4021] first according to their isoelectric point (pI) and then according to their molecular weight. In addition, unlabelled sodium-dodecyl-sulphate-solubilized platelets were separated on a two-dimensional polyacrylamide gel and the glycoproteins were identified by binding of 125I-labelled Lens culinaris lectin (specific for mannose and glucose). In one Glanzmann's thrombasthenia patient glycoproteins IIbA1 and IIIaA1 were absent and in two others lower amounts of two glycoproteins were found in positions similar or close to these two membrane glycoproteins. The terminal sialic acid moieties of major glycoproteins (IbA1, IbB1 and IIIbA1) were more intensely labelled in Glanzmann's thrombasthenia than in normals and these glycoproteins had an altered pI. A glycoprotein tentatively designated as Ic/IIa(?) had an altered pI and was labelled more intensely in Glanzmann's thrombasthenia platelets than in normals. A number of low-molecular-weight glycoproteins (IVa, IVb, VII) and one high-molecular weight glycoprotein normally found in platelets of healthy donors were reproducibly not detected in Glanzmann's thrombasthenia platelets. These results obtained by a combination of highly sensitive techniques strongly indicate that in Glanzmann's thrombasthenia the absence or reduction of two major membrane glycoproteins (IIbA1, IIIaA1) is not the only defect but that there appears to be a profound perturbation of the platelet membrane surface.

Blood Platelet Disorders↗
PubMed1981

Refractoriness of diabetic platelets to inhibitory prostaglandins.

Inhibition of collagen-induced platelet aggregation by either endothelial extracts, prostacyclin, prostaglandin E1 or prostaglandin D2 was investigated. The inhibition was less efficient with diabetic platelets than with platelets from normal donors. The refractoriness of diabetic platelets to inhibitory prostaglandins was observed both with platelet-rich plasma and platelets isolated from their plasma. Moreover levels of cyclic AMP in resting platelets and after stimulation by either PGE1 or PGD2 were lower in diabetic platelets than in normal platelets. It is concluded that the weaker response of diabetic platelets to inhibitory prostaglandins could be related to their content in cyclic AMP.

Adolescent↗
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

[Lupus anticoagulant screening: comparison of 5 tests (author's transl)].

Five tests were carried out on 15 lupus anticoagulant plasmas: activated partial thromboplastin time with a commercial reagent (APTT); kaolin partial thromboplastin time with a human brain extract (KPTT-H); tissue thromboplastin inhibition test (TTI); Russell's viper venom time without phospholipid (RVVT); assay of phospholipid-related procoagulant activity (PPA). One of our criteria for diagnosis of lupus anticoagulant was a prolonged APTT; hence this test was abnormal in all 15 plasmas. An abnormal TTI was observed for the 15 lupus anticoagulants while PTT-H was abnormal in only 13 cases, RVVT in 11 cases and PPA assay in 12 cases. In another study evaluating the specificity of TTI and PPA assay, the TTI appeared to be influenced by factor II, V, VII, and X deficiencies, but not by factor VIII: C, IX, XI, and XII deficiencies, or by anti-factor VIII: C anticoagulants. Furthermore, the TTI displayed a weak sensitivity to heparin. On the other hand, the PPA assay was influenced by anti-factor VIII: C anticoagulants of high potency and was found to be more sensitive to heparin than the TTI. Our overall results emphasize the value of TTI as a screening test for the lupus anticoagulant.

Blood Coagulation↗
PubMed1980

Dihomogammalinolenic acid (20:3 omega 6) is more anti-aggregatory than eicosapentaenoic (20:5 omega 3) in a platelet-endothelial cell mixture.

The effect of 20:3 omega 6, the precursor of 1 series prostaglandins was to inhibit platelet aggregation more strongly than either 20:5 omega 3, the precursor of 3 series prostaglandins or 20:3 omega 3 which is not a substrate of prostaglandin synthetase. When platelets and dissociated endothelial cells were pretreated with 20:3 omega 6, platelet aggregation in the presence of endothelial cells was much more inhibited than after 20:5 omega 3 pretreatment.

8,11,14-Eicosatrienoic Acid↗
PubMed1980

Fatty acids bound to serumalbumin decrease the half-life of thromboxane A2.

The half-life of thromboxane A2 is increased in plasma as well as in a buffer containing serumalbumin. Moreover, the half-life of thromboxane A2 depends on the amount of unesterified fatty acids bound to albumin. When more fatty acids are bound, the half-life is shortened. This shortening is accompanied by a decrease of the aggregating activity of thromboxane A2.

Chemical Phenomena↗