Search PubMed⌕ Search

Biomedical subjects

G Tobelem

Publications and source records attributed to G Tobelem.

At least 181 records · Page 10Linked to original sources
PubMed1978

Effect of prostacyclin (PGI2) on platelet adhesion to rabbit arterial subendothelium.

The effect of prostacyclin on platelet aggregation and adhesion was investigated in everted pieces of rabbit abdominal aorta, from which the endothelium had previously been removed. Citrated human blood, to which different, concentrations of prostacyclin (0.1-100 ng/ml) were added, was perfused through the vessels, after which sections were examined and evaluated by light microscopy. Prostacyclin inhibited thrombus formation at concentrations greater than 0.1 ng/ml, whereas 20 ng/ml were required to reduce the amount of adhesion to the subendothelial surface. Thus prostacyclin prevents thrombus formation at much lower concentrations than are needed to inhibit platelet-vessel wall interaction.

Animals↗
PubMed1978

Platelets from "giant platelet syndrome (BSS)" are discocytes and normal sized.

A comparison is made between the shape of human platelets obtained from nine normal donors and two BSS donors. Sizes are evaluated from a cinematographic analysis of freely rotating, unfixed, and glutaraldehyde-hardened platelets in citrated PRP and of platelets on blood smear. On blood smeae, the mean diameters of BSS platelets are 1.7 to 1.8 times larger than those of normal platelets, with a major fraction having a diameter greater than 2.5 micrometer. As for normal donors, 80% to 90% BSS platelets in PRP are in the disc form (discocyte). In addition, they are essentially indistinguishable from a normal discocyte. Echinocytes (spherical forms with pseudopods) for BSS have a main body diameter (i.e., excluding pseudopods) 1.6 times larger than normal and in addition a reduced number of pseudopods. The results demonstrate that the giant size of BSS platelets results from abnormal behavior of these platelets during the preparation of the blood smear. It is suggested that this disorder is associated with a defect in the mechanism of platelet shape change.

Adult↗
PubMed1978

Acquired IgG antibody occurring in a thrombasthenic patient: its effect on human platelet function.

In subagglutinating amounts, an IgG antibody isolated from the plasma of a polytransfused thrombasthenic patient (L) inhibited ADP-, epinephrine-, collagen-, and thrombin-induced aggregation of normal human platelets. The inhibition of ADP-induced aggregation was strongly diminished following the prior incubation of the antibody with control human platelet stroma but not with the stroma prepared from the platelets of two different thrombasthenic patients. The IgG(L) did not affect the binding of 14C-ADP to control human platelet membranes and did not inhibit the ADP-induced shape change. Bovine factor VIIIVWF-induced agglutination and ristocetin-induced aggregation of control human platelets were not inhibited in the presence of the antibody. The IgG(L) strongly inhibited ADP-induced retraction of reptilase clot and thrombin-induced clot retraction. This antibody therefore induced a thrombasthenialike state in normal human platelets, suggesting that the antigenic site recognized by the antibody plays a central role in the later stages of the mechanism of platelet aggregation induced by physiologic aggregation-inducing agents.

Adenosine Diphosphate↗
PubMed1977

Adhesion and aggregation of human platelets to rabbit subendothelium. A new approach for investigation: specific antibodies.

An SgG antibody occurring in a recently transfused thrombasthenic patient inhibited all the ADP-mediated aggregations and platelet-platelet interaction (thrombus formation) on rabbit aorta subendothelium; another IgG antibody occurring in a multitransfused Bernard-Soulier patient inhibited ristocetin and bovine factor VIII mediated aggregation and platelet-subendothelium interaction.

Animals↗
PubMed1977

Molecular defect in platelets from patients with bernard-soulier syndrome.

An IgG antibody isolated from the serum of a patient with the Bernard-Soulier syndrome induced platelet agglutination in the platelet-rich plasma of 50 normal subjects regardless of their ABO, KOa, KOb, HLA, or PlA1 types. This antibody was nonreactive with platelets from three other Bernard-Saulier syndrome patients. Indirect immunoprecipitation tests using this serum (or purified IgG) and soluble membrane antigens labeled with 125I that had been extracted from normal platelets by the nonionic detergent Nonidet P-40 gave a single radioactive peak at 150,000 MW in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These findings strongly suggest that the antigenic determinant reacting with this antibody is absent from platelets of Bernard-Soulier syndrome patients and that the deficient molecule is of 150,000 MW. The role of this molecule in subendothelial adhesion and macromolecular-mediated aggregations is discussed.

Antibodies↗
PubMed1976

[Myelomatous G-kappa immunoglobulin with antistreptolysin O activity].

A new case of myeloma with antistreptolysin O activity is described. The myeloma protein is Kappa IgG. By precipitation of this myeloma IgG with anti-Kappa antiserum, the antistreptolysin O activity is completely inhibited. For the antibody activities of the myeloma protein described in the litterature, the antistreptolysin O activity is the most frequently found. With this 19th case the authors discuss the fundamental problems of the antibody activities of myeloma protein.

Antibody Specificity↗
PubMed1976

[Epileptic seizure revealing a cerebral arterial accident during administration of oral contraceptives with platelet function disorders].

The authors observed the onset of an epileptic fit in a 27 year-old woman, ten months after starting treatment with the contraceptive pill. Carotid arteriography revealed the existence of non-obstructive lesions in the area supplied by the left anterior cerebral artery. Disorders of platelet aggregation and disaggregation were demonstrated 15 days after stopping the contraceptive treatment. The significance of these abnormalities is discussed in the light of data in the literature.

Adult↗
PubMed1976

Bernard-Soulier syndrome: a new platelet glycoprotein abnormality. Its relationship with platelet adhesion to subendothelium and with the factor VIII von Willebrand protein.

A decreased platelet adhesion to rabbit aorta subendothelium (Baumgartner technique) is confirmed in the Bernard Soulier (giant platelet) syndrome. Electron microscope techniques using a purified antibody against Factor VIII/von Willebrand protein, revealed an apparently normal presence of the Factor VIII/von Willebrand protein on the Bernard Soulier platelets. Electrophoretic characterization of the major protein and glycoprotein components of the Bernard Soulier platelets following sodium dodecyl sulfate solubilization indicated a relatively normal protein content but suggested a reduced content of the 155,000 molecular weight major platelet glycoprotein. This was confirmed by a reduced release of high molecular weight acidic glycopeptides following incubation of washed Bernard Soulier platelets with trypsin. It is proposed that this abnormality may be related to the previously reported reduced sialic acid content and the reduced electrophoretic mobility of the Bernard Soulier platelets and that a glycoprotein reduced or abnormal in the Bernard Soulier platelets is necessary for the normal adhesion of platelets to subendothelium.

Adult↗
PubMed1976

[Clinical and biological studies in the Bernard-Soulier syndrome (author's transl)].

Bernard-Soulier syndrome is a rare constitutional thrombopathy, the main clinical feature is a bleeding tendency which is variable. The long bleeding time, in spite of a normal or little decreased platelet count, has been recently explained: the giant platelets have a defective adhesion to subendothelium. This abnormal adhesion could be related with an abnormal pattern of platelet membrane glycoproteins. Interactions between vessel wall, von Willebrand's factor and platelets are discussed.

Adenosine Diphosphate↗
PubMed1976

[The development of arterial thrombi].

The factors involved in arterial thrombosis include the endothelial and subendothelial cells of the arterial wall, platelets and other blood cells, plasma factors and blood flow. An arterial thrombus arises from an interaction between platelets and the subendothelium (basement membrane and microfibrils) which has been shown by recent experiments to have a thrombogenic propensity. The particular structure of the subendothelium and its glycoprotein membrane receptors for platelets is implicated on thrombogenesis which requires the intervention of von Willebrand's factor; the well-known role of collagen is also important. An arterial thrombosis may evolve into a mural thrombus or may spread or form an embolus.

Arterial Occlusive Diseases↗
PubMed1975

[Platelet membrane glycoprotein defect, molecular basis for the abnormal adhesion of platelets to the subendothelium in thrombocytic hemorrhagic dystrophy].

A large reduction in the staining capacity of a glycoprotein of 155 000 M.W. was observed in the platelets of 2 macrogiant platelets syndrome patients, associated with a reduced platelet adhesion to rabbit aorta subendothelium and with the presence of von Willebrand protein on these platelets as revealed by an antihuman factor VIII-Von Willebrand protein rabbit antibody. These results led the authors to propose a strong hypothesis on the role of this glycoprotein rich in sialic acid - in platelet adhesion to subendothelium.

Adult↗