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Biomedical subjects

M Dechavanne

Publications and source records attributed to M Dechavanne.

At least 91 records · Page 5Linked to original sources
PubMed1985

Intravenous plasmin-treated gammaglobulin therapy in idiopathic thrombocytopenic purpura. Results in 40 patients.

A study of the effects of high-dose IV plasmin-treated IgG was undertaken in 40 patients (30 children and 10 adults) with idiopathic thrombocytopenic purpura (ITP). After a first course of treatment, a success therapy (platelet counts greater than 100 X 10(9)/l) was observed in 21 patients. The results after additional courses of pH 4 treated IgG in 7 patients tended to indicate that the 2 kinds of concentrates might induce similar platelet responses. No significant side-effects were observed. Platelet associated (PA), IgG, IgM and C3 levels were determined before therapy and on the 7th day after the first infusion (day 8) in 27 patients (36 courses). In spite of great variability, overall results showed a significant decrease in PA IgG (P less than 0.05), PA IgM (P less than 0.01) and PA C3 (P less than 0.001) at day 8. A significant inverse relationship was found between either PA IgG, or PA IgM or PA C3 levels, and platelets counts (respectively, r = -0.57, -0.55, -0.66, P less than 0.001). Our results also showed that pretreatment platelet counts were higher in patients with success therapy (25.8 +/- 16.9 X 10(9)/l) than in others (11.3 +/- 12.1 X 10(9)/l, P less than 0.001). This suggested that pretreatment platelet counts could help predicting the platelet response.

Adolescent↗
PubMed1984

Inhibition of platelet aggregation and thromboxane synthesis after intake of small amount of icosapentaenoic acid.

Elderly people ingested 150 mg/day of icosapentaenoic acid (20:5n-3) or a placebo for one month. Platelet aggregation, platelet arachidonate metabolism and the fatty acid composition of both plasma and platelet lipids were investigated before and after the intake. Platelet aggregation induced by collagen, epinephrine or low concentrations of ADP was significantly reduced after 20:5n-3 intake. Besides, the main oxygenated product formation from endogenous platelet arachidonate under thrombin stimulation was markedly decreased after the 20:5n-3 supplementation. Such a decrease was absent after placebo. Moreover, no modification in the fatty acid composition of both plasma lipids and platelet phosphatidylcholine could be observed. We conclude that intake of low amounts of 20:5n-3 by elderly people, is able to lower their platelet sensitivity to aggregating agents, probably by decreasing the endogenous formation of platelet thromboxane A2, although no modification in the fatty acid composition was detected.

Adenosine Diphosphate↗
PubMed1984

Isolation of thrombospondin released from thrombin-stimulated human platelets by fast protein liquid chromatography on an anion-exchange Mono-Q column.

Thrombospondin, a glycoprotein found in human platelet alpha granules, is thought to play a major role in platelet haemostatic functions. A rapid method to isolate thrombospondin for functional and structural studies was developed. Freshly prepared supernatants from thrombin-stimulated platelets were separated on an anion-exchange Mono-Q column on a fast protein liquid chromatography system. Detection of thrombospondin in the eluted peaks was performed using sodium dodecyl sulphate-polyacrylamide gel electrophoresis combined with silver staining and a solid-phase radioimmunoassay with monoclonal antibodies directed against thrombospondin and other platelet granule glycoproteins. Thrombospondin was isolated rapidly to a high degree of purity using the fast protein liquid chromatography Mono-Q system (20 min), compared with the time taken with other techniques.

Antibodies, Monoclonal↗
PubMed1984

Relationship between cyclic AMP and thromboxane formation in platelet-endothelial cell interactions.

Human platelet aggregation was triggered in the presence of various numbers of cultured endothelial cells. Thromboxane B2 formation and platelet cyclic AMP were also measured. Using a low concentration of thrombin (0.025U/ml) as aggregating agent, the inhibition of platelet aggregation correlated with that of thromboxane formation and was directly related to both the number of endothelial cells and platelet cyclic AMP. In contrast, using arachidonic acid (10(-5)M) instead of thrombin, platelet aggregation could be abolished although thromboxane formation was not affected. These results suggest that platelet aggregation induced by low concentrations of thrombin might be dependent on prostaglandin endoperoxides/thromboxane A2 production which could be inhibited by cyclic AMP. The normal synthesis of thromboxane B2 from exogenous arachidonate indicates that cyclic AMP is only active upon the liberation of endogenous arachidonate from platelet phospholipids.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

Drugs effect on platelet survival time: comparison of two pyrimido-pyrimidine derivatives in patients with aortic or mitral replacement.

A prospective randomized trial of the effects of 2 antiplatelet aggregating drugs, dipyridamole (375 mg/d), a related substance RA 233 (1500 mg/d) and placebo, concomitantly with oral anticoagulants, was carried out in patients with prior valvular replacement. The study was aimed to determine effect on platelet survival time (PST) of these 2 agents. The trial sample consisted of 40 males and 15 females aged 40-70 years (average 53 years). 32 received Björk-Shiley valve in aortic position, 23 underwent mitral valve replacement: 3 with Cooley-Cutter, 11 with Lillehei-Kaster 500 and 9 with Starr-Edwards 6120 prostheses; 28 patients had aortic stenosis, 21 aortic insufficiency. All the PST measured after 3 months of treatment were within normal ranges and not different between placebo, dipyridamole or RA 233 treated subjects: averages in days were, respectively, 7.49, 7.11 and 6.88. The present study did not support the claim that modern valve prosthesis could lead to a shortened PST.

Adult↗
PubMed1984

Fatty acid composition in native and cultured human endothelial cells.

Endothelial cells from human umbilical veins were isolated by collagenase treatment. Cells were cultured in the presence of either 20% fetal bovine serum (FBS) or 20% human serum (HS). At confluency, endothelial cell lipids were labeled with tracer concentrations of tritiated arachidonic acid, then extracted and separated into lipid subclasses by thin layer chromatography. The fatty acid composition of each lipid class was determined by glass capillary gas-liquid chromatography analysis and compared to that of cells freshly isolated from the cord (NC cells). The fatty acid compositions differed only in phospholipids. Polyunsaturated fatty acids (PFAs), arachidonic, and linoleic acids were depleted in FBS cell phospholipids and replaced by both stearic and oleic acids. No significant difference could be observed between NC cell and HS cell phospholipids. We conclude that PFAs might be decreased in FBS cells because of the relative paucity of PFAs in FBS as compared to HS. It seems therefore more convenient to cultivate endothelial cells in the presence of HS, especially in respect to their phospholipid content of arachidonic acid, which is the physiological reservoir for prostacyclin synthesis.

Animals↗
PubMed1984

Lipoxygenase activity of intact human platelets.

The oxygenation by lipoxygenase of different icosaenoic and docosaenoic acids by intact human platelets was studied. The HPLC analysis of the hydroxy compound (s) derived from icosaenoic acids showed that the 12-derivatives predominate. The increase of the fatty acid concentration markedly enhanced their oxygenation except for icosapentaenoic acid. The conversion of this acid into its hydroxy derivative rose in the presence of arachidonic acid, probably through both its cyclo-oxygenase and lipoxygenase product formation. Since 12-hydroxy-icosaenoic acids are modulators of PGH2-induced platelet aggregation, we conclude that the interactions between polyunsaturated fatty acids during their oxygenation by platelet lipoxygenase could be relevant to the regulating activity of dietary fatty acids.

Blood Platelets↗
PubMed1984

Uptake and effect on arachidonic acid oxygenation of some icosaenoic acids in human platelets.

8,11,14-icosatrienoic (DHLA), 5,8,11,14,17-icosapentaenoic (EPA) acids (the monoenoic and trienoic prostaglandin precursors, respectively) and 5,8,11-icosatrienoic acid (20:3n-9) were pre-coated onto albumin and then incorporated into platelet lipids. Around 80% of the total incorporation concerned their acylation into phospholipids and a few percentage was oxygenated through the cyclooxygenase and/or lipoxygenase pathways, simulating therefore the in vivo situation. Such modified platelets normally oxygenated exogenous arachidonic acid (AA) while (only when enriched with DHLA or EPA) they produced less oxygenated derivatives of AA under thrombin stimulation. This indicates that endogenous AA liberation was decreased in both DHLA and EPA-rich platelets, which might be related to the formation of inhibitory prostaglandins from these polyunsaturated fatty acids.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1983

Monoclonal antibodies against platelet membrane glycoproteins. Characterization and effect on platelet function.

The specificity of five monoclonal antibodies (P1-P6) against platelet surface components was determined by immunoprecipitation of surface-labelled platelets from normal donors and patients with known platelet glycoprotein defects, followed by analysis by gel electrophoresis. Three (P2, P4 and P6) precipitated glycoproteins IIb and IIIa and, in addition, P2 precipitated glycoprotein Ia. P1 precipitated normally only glycoprotein Ib also Ia when the platelets were pretreated with neuraminidase. P3 precipitated principally glycoprotein Ia but glycoprotein Ib was also weakly precipitated. The effects of the monoclonals on platelet function were tested. P1 and P2 completely inhibited and P3 slightly inhibited thrombin-induced platelet aggregation. P2 also inhibited collagen-induced aggregation and partially inhibited ADP-induced platelet aggregation. P3, P4 and P6 partially inhibited ADP-induced platelet aggregation. None had any effect on ristocetin-induced aggregation despite P1 and P3 binding to glycoprotein Ib. These results confirm the role of glycoproteins IIb and IIIa in aggregation induced by various agents and suggest that the function of glycoprotein Ib in thrombin-induced aggregation is more important than previously suspected and that glycoprotein Ia may also be involved in platelet functions.

Animals↗
PubMed1983

Potentiating effect of 5,8,11-eicosatrienoic acid on human platelet aggregation.

5,8,11-Eicosatrienoic acid (20:3 omega 9), a fatty acid increased in the platelet phospholipids of man and animals fed saturated fats, was either added to human platelets simultaneously with the aggregating agents, or incorporated into the platelet phospholipids by preincubation. 20:3 omega 9 markedly increased the response of platelets to all aggregating agents tested when added simultaneously with the agent, but solely to thrombin and ionophore, after incorporation into the platelet phospholipids. The potentiating effects of 20:3 omega 9 on thrombin aggregation do not appear to be related to prostaglandin formation, but rather to the production of a monohydroxy derivative through the lipoxygenase pathway.

8,11,14-Eicosatrienoic Acid↗
PubMed1983

Plasma lipoproteins and fatty acid composition after "minipill".

A study of the effect of a low-dose oral contraceptive, Adepal (ethinyl estradiol and levonorgestrel, 30 and 150 micrograms on the 5th to 12th, 40 and 200 micrograms on the 13th to 28th, respectively) on the blood lipids, lipoproteins and fatty acid composition has been conducted on 13 young women before and after six months of treatment. All together, total cholesterol concentration did not vary; however, the high cholesterol values decreased whereas the low cholesterol values increased with the pill. Triglyceride levels increased significantly (p less than 0.001). High density lipoprotein (HDL)-cholesterol decreased clearly (p less than 0.001) regardless of the cholesterol value at the beginning; low and very low density lipoprotein (LDL + VLDL)-cholesterol increased slightly, as well as the apoprotein B (Apo B) concentration (p less than 0.05). The lipoprotein electrophoresis showed intermediate bands (IDL) in 5/12 of the women after treatment. The three major classes of lipoprotein showed some variations in the fatty acid composition after the oral contraceptive; in any lipid class from any lipoprotein, the linoleic (18: 1 omega 6), arachidonic (20: 4 omega 6) and eicosapentaenoic (20: 5 omega 3) acids decreased whereas the palmitic (16: 0) and oleic (18: 1 omega 9) acids increased. Our results suggest that a low-dose contraceptive like Adepal produces, nevertheless, some significative modifications of plasma lipids and lipoproteins.

Adult↗
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↗