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Biomedical subjects

J Vermylen

Publications and source records attributed to J Vermylen.

At least 289 records · Page 16Linked to original sources
PubMed1977

Turnover of fibrinogen, plasminogen, and prothrombin during exercise in man.

The turnover of biologically intact high-purity 125I- and 131I-labeled fibrinogen, plasminogen, and/or prothrombin was studied in 16 untrained healthy subjects before and during strenuous physical exercise on a bicycle ergometer (repeated 4 times/day for 2 days). The exertion resulted in the well-known changes in the coagulation and fibrinolytic tests but did not induce changes in the concentration of fibrinogen, plasminogen, or prothrombin in the plasma. A significantly increased catabolism of fibrinogen and plasminogen but not of prothrombin was observed. The extent of Aalpha-chain degradation of fibrinogen in the plasma was quantitated before and 2 h after exercise, and a significant increase in degraded Aalpha chains was found in the postexercise samples. Immunochemical estimation of plasmin-antiplasmin complex in four subjects revealed a small increase after exercise in three of them. All these data support the concept that plasminogen activation and plasmin-induced fibrinogen degradation occur to some extent in man following strenuous physical exercise.

Adult↗
PubMed1977

Effect of furosemide on plasma fibrinolytic activity and urokinase excretion.

Plasma fibrinolytic activity, as measured by the fibrin-plate method, is enhanced after a single intravenous administration of 40 mg of furosemide. This effect becomes evident within 30 min and a peak response is attained 6 h after i.v. administration. On successive administration of furosemide, the fibrinolytic effect persists and the second peak becomes manifest again after 6 h. Following the parenteral administration of furosemide there is an initial decrease of urinary urokinase excretion which returns to a normal level after 3 to 6 h. Possible mechanisms which may explain the enhanced fibrinolytic activity after furosemide administration are discussed.

Endopeptidases↗
PubMed1976

Molecular size distribution of fibrinogen derivatives formed in vitro and in vivo: a chromatographic study.

Using gel chromatography, fibrinogen derivatives present in purified systems or in biological fluids were separated and partially characterized. Eight groups of fibrinogen derivatives could be separated by gel filtration through 6% agarose in large columns, four with an elution volume smaller and four groups with an elution volume larger than that of fibrinogen. Careful calibration of the column allowed estimation of the diffusion coefficients of some of the derivatives and, thus, comparison with derivatives previously identified. Three, rather than two, groups of intermediate derivatives were observed during the degradation of human fibrinogen by plasmin in vitro or in vivo. One of these had a marked tendency to polymerize. A rather distinct difference in elution pattern was found between plasma obtained during streptokinase administration and from patients with intravascular coagulation.

Blood Coagulation↗
PubMed1976

Factor VIII and human platelet aggregation. I. Evience that the platelet aggregating activity of bovine factor VIII is a property of its 'carrier protein' subunit.

Bovine factor VIII is a potent inducer of aggregation of human platelets. Upon gel filtration of five-thousand-fold purified material in 0.5 M CaCl2, bovine factor VIII is separated into high and low molecular weight components; the former contains both a 'carrier protein' and platelet aggregating activity, the latter the procoagulant activity (low molecular weight factor VII, LMW-FVIII). Upon removal of Ca2+ ions, LMW-F VIII recombines with the 'carrier protein'. LMW-F VIII modifies aggregation by 'carrier protein', but not aggregation by undissociated bovine factor VII, adenosine-5'-diphosphate or adrenaline. This finding indicates that the platelet aggregating activity in indeed a property of the 'carrier protein'.

Animals↗
PubMed1976

Factor VIII and human platelet aggregation. II. Characteristics of aggregation of human platelets by bovine factor VIII.

Bovine factor VIII aggregates human platelets either in a strong single wave at high concentration (10 mug/ml platelet suspension) or in two waves at low concentration (0.2-I mug/ml). The strong single wave of aggregation is not associated with release of [14C]serotonin or beta-glucuronidase; the high concentration does not induce retraction of reptilase-clotted platelet-rich plasma. Wtih the low concentration, relase of [14C]serotonin is observed just prior to the onset of the second wave of aggregation; release of beta-glucuronidase does not occur at any moment. The low concentration of bovine factor VIII induces moderate retraction of reptilase-clotted platelet-clotted platelet-rich plasma, which is inhibited by acetylsalicylic acid, indomethacin and apyrase, indicating that it is a consequence of release of platelet adenosine-5'-diphosphate. It has previously been suggested tht carbohydrate groups are involved in the human platelet-bovine factor VIII interaction, since galactose oxidase and periodate oxidation abolish the platelet aggregating activity of bovine factor VIII. The present study shows that these oxidizing substances also induce a degradation of bovine factor VIII, so that the exact role of carbohydrate groups in the aggregation process remains to be established.

Animals↗
PubMed1976

Factor VIII and human platelet aggregation. III. Further studies on aggregation of humna platelets by neuraminidase-treated human factor VIII.

When highly purified human factor VIII is submitted to agarose gel chromatography in the presence of 0.5 M CaCl2, the procoagulant activity (low molecular weight factor VIII, LMW-F VIII) is separated from the void volume protein (Vo-VIII). Upon incubation of human factor VIII with purfied neuraminidase, a very stable platelet aggregating activity develops in the "Vo-VIII' fraction, not in the "LMS-FVIII' part. Evidence is provided that the generated aggregating activity is a property of the 'carrier protein' for LMW-F VIII. Desialylated factor VIII retains its antigenic reactivity, its procoagulant or ristocetin cofactor properties and the capacity of its subunits to dissociate and recombine. Neuraminidase-treated human factor VIII, in contrast to intact bovine factor VIII or intact human factor VIII in the presence of restocetin, does not induce aggregation of EDTA-platelet rich plasma, of congenitally afibrinogenaemic platelet rich plasma, nor of washed platelets.

Chromatography, Agarose↗
PubMed1976

Significance of urinary excretion of fibrin degradation products during treatment of glomerulonephritis.

189 patients with various types of glomerular disease were studied. Creatinine clearance, protein excretion and urinary excretion of fibrin degradation products (FDPs) were measured before and at various intervals (up to 42 months) after starting treatment with indomethacin, alone or in combination with other drugs. The following observations were made: a. Patients with a urinary FDP in excess of 2 mg/24 hours before treatment had a significantly lower creatinine clearance and a significantly higher protein excretion than patients excreting less than 2 mg FDP/24 hours, indicating that FDP excretion reflects the severity of the renal disease. b. During treatment, the incidence of high FDP excretion decreases progressively, but remains high in patients who ultimately develop renal insufficiency. c. There is no correlation between the initial value of FDP excretion and the subsequent changes in creatinine clearance and proteinuria during treatment. This implies either that the initial FDP excretion has no prognostic value or, perhaps more likely, that disease activity is modified by treatment. d. The best correlation between FDP excretion and evolution is found in proliferative glomerulonephritis. There are reason to suppose that, in this group at least, the treatment influenced the evolution of the disease.

Creatinine↗
PubMed1976

Factor VIII and human platelet aggregation. IV. Effect of proteolytic enzymes on platelet aggregation by factor VIII.

During digestion of highly purified bovine factor VIII or neuraminidase-treated human factor VIII by plasmin the procoagulant activity is destroyed more rapidly than the aggregating activity. At an intermediate stage, fragments are transiently formed, which inhibit platelet aggregation by the respective undigested materials, but without corssed inhibition. During proteolysis by plasmin, human factor VIII retains antigenic and restocetin cofactor properties. Contrary to previous observations obtained with less purified preparations, plasmin digest of human or bovine factor VIII do not inhibit ADP-induced platelet aggregation. Thrombin and reptilase do not modify the aggragating activities of bovine and neuraminidase-treated human factor VIII.

Animals↗
PubMed1976

Platelet-endotoxin interaction: a review.

The studies reviewed in the present manuscript outline the effects of bacterial endotoxins on human and animal platelets. In animals the endotoxin administration is followed by thrombocytopenia, presence of platelet aggregates in the blood vessels of several organs, appearance of appreciable quantities of serotonin in plasma and increased platelet factor 3 availability. These in vivo effects can readily be explained by the in vitro demonstration that endotoxin aggregates platelets, induces release of vasoactive amines and adenine nucleotides and activates platelet factor 3. There is substantial evidence suggesting that the mechanism of this animal platelet-endotoxin interaction is immunological and complement dependent. In humans thrombocytopenia is frequently observed in endotoxemia as encountered during Gram-negative sepsis indicating that platelets are involved in some of the biological effects endotoxin. In vitro experiments demonstrate that several endotoxin preparations significantly enhance a weak procoagulant activity of human platelets different from platelet factor 3.

Animals↗
PubMed1976

Modification of venous stasis thrombosis in the rat by platelet-active drugs and by heparin.

In rats, stasis thrombosis of a renal vein was produced by the occlusion of a vascular segment after induction of systemic hypercoagulability by i.v. injection of ellagic acid. Prostaglandin E1, at doses which reduced platelet retention by glass beads (6 mug/min/300 g i.v.) only slightly reduced the thrombus size. The platelet release inhibitors suprofen and indomethacin, at doses which prolonged tail bleeding time in rats (50 mg/kg i.v.) had no effect on the thrombus size. Heparin (10 and 20 U/kg i.v.) produced a marked, dose-related reduction of venous thrombosis. The platelet-active compound VK774, at the dose levels of 50 to 10 mg/kg i.v., also reduced the thrombus size to about half that of controls. Lower doses (5, 2.5 mg/kg i.v.) had a progressively weaker effect. Binding to ellagic acid or induction of coagulation changes by VK774 are proposed as possible mechanisms of action. It is concluded that, in comparison with the contribution of plasma coagulation, the participation of the aspects of platelet function we measured in the development of venous stasis thrombosis is comparatively small.

Animals↗
PubMed1975

Sodium acetate buffer: a diluent of choice in the clot lysis time technique.

Sodium acetate buffer, 0.12 M, pH 7.4 as a diluent in the low temperature technique of dilute clot lysis time, is more effective in accelerating the velocity of lysis than phosphate buffer of similar pH and molarity. A uniform shape of the clot is maintained throughout the digestion in sodium acetate buffer and the end point of lysis is characteristically marked by an abrupt and sharply defined disintegration. Sodium acetate buffer can be employed advantageously in this technique not only to improve the observation but also to shorten the lysis times.

Acetates↗