Direct radioimmunological measurement of thromboxane B2 in plasma.
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Humans↗
Biomedical subjects
U Delvos
Publications and source records attributed to U Delvos.
Quantitative assessment of soluble fibrin in plasma by affinity chromatography--a comparative study with desAA-fibrin, desAABB-fibrin and fibrinogen.
A quantitative determination of soluble fibrin in plasma was carried out by affinity chromatography. For this purpose, desAA-fibrin and fibrinogen immobilized on Sepharose 4B were used at the stationary side whereas batroxobin-induced 125I-desAA-fibrin or thrombin-induced 125I-desAABB-fibrin mixed with plasma containing 131I-fibrinogen represented the fluid phase. The binding characteristics of these mixtures to the immobilized proteins were compared at 20 degrees C and 37 degrees C. Complete binding of both types of fibrin to the immobilized desAA-fibrin was always seen at 20 degrees C as well as at 37 degrees C. However, binding of soluble fibrin was accompanied by substantial binding of fibrinogen that was more pronounced at 20 degrees C. Striking differences depending on the temperature at which the affinity chromatography was carried out, were documented for the fibrinogen-fibrin interaction. At 20 degrees C more than 90% of the applied desAA-fibrin was bound to the immobilized fibrinogen whereas at 37 degrees C only a mean of 17% were retained at the fibrinogen-Sepharose column. An opposite finding with regard to the tested temperature was made with the desAABB-fibrin. Nearly complete binding to insolubilized fibrinogen was found at 37 degrees C (95%) but only 58% of the desAABB-fibrin were bound at 20 degrees C. The binding patterns did not change when the experiments were performed in the presence of calcium ions. The opposite behaviour of the two types of soluble fibrin to immobilized fibrinogen at the different temperatures, together with the substantial binding of fibrinogen in the presence of soluble fibrin to insolubilized fibrin in every setting tested, devaluates affinity chromatography as a tool in the quantitative assessment of soluble fibrin in patient's plasma.
Body Temperature↗
Binding of fibrinogen to cultured bovine endothelial cells.
The binding properties of purified bovine fibrinogen to bovine aortic endothelial cells have been examined in a tissue culture system. Endothelial cells bound 125I-fibrinogen in a calcium dependent fashion. Removal of calcium by EDTA instantaneously detached most of the cell-associated fibrinogen. Binding of fibrinogen to the endothelial cells was not saturable with time and dosage. Competition studies and displacement experiments did not indicate the involvement of a specific receptor site for the fibrinogen-endothelial cell-interaction. Bovine serum albumin provided in the physiological ratio of 20:1 to fibrinogen competed as effectively as unlabelled fibrinogen for 125I-fibrinogen binding to the endothelial cells. And furthermore, internalization of cell-associated tracer into the endothelial cells that could be demonstrated in the presence of serum free medium did not occur in the presence of albumin. These data suggest that fibrinogen binding to intact bovine endothelial cells is unspecific and presumably negligible in the presence of physiological albumin concentrations.
Animals↗
Effect of the heparinoid pentosan polysulphate (SP 54) on the functional properties of cultured bovine aortic endothelial cells.
The effect of the heparinoid, pentosan polysulphate (PP) on the proliferative behaviour of cultured bovine endothelial cells (EC) was examined. In addition, the toxicity of the drug towards EC, its influence on prostacyclin production and release, and on cell-associated plasminogen activator activity was determined. At a concentration of 10 micrograms/ml in the culture medium, PP exerted a growth promoting effect on EC. Increased cell numbers were accompanied by increased 3H-thymidine incorporation into cellular DNA compared with controls, however, final density of the cells was not affected. In contrast, at doses of 1 mg/ml the growth of EC was substantially slowed down. This finding did not reflect cell injury as shown by an unaltered release of 51Cr from the cells. Incubation of PP with EC had no influence on the prostacyclin release from the cells neither on the accumulation of the metabolite in the culture fluid over 24 hours nor on the releasing capacity upon stimulation with arachidonic acid. PP increased the cell-associated plasminogen activator activity in growing cells and counteracted in cultures at final density the inhibitory effect of serum on the intracellular plasminogen-activator activity. Our results suggest that stimulation of the fibrinolytic activity of the endothelium and a growth promoting effect for endothelial cells that may lead to faster coverage of small lesions could contribute to the antithrombotic potency of pentosan polysulphate in vivo.
Animals↗
[Regulation of blood coagulation].
The patency of the vascular tree as well as thrombus formation are achieved by the interactions of several components of the circulating blood and the vessel wall. Circulating glycoproteins (coagulation factors), cellular elements of the blood (platelets), the fibrinolytic system, the endothelium of the vasculature and inhibitors that are present in the blood stream are involved in the maintainance of the subtle balance between anti-coagulant and pro-coagulant forces. Regulation of the activity of thrombin represents a key event in this process.
Anticoagulants↗
Interactions of vascular wall cells with collagen gels.
Culture properties of bovine aortic endothelial cells and bovine aortic smooth muscle cells have been examined in relation to collagen gels. Endothelial cells grown on collagen maintain typical monolayer morphology not only in relationship to the overlying medium but also with respect to the collagen substrate. Endothelial cells placed within a collagen matrix assume a mycelial pattern resembling that of the microvasculature. Overlayment of confluent endothelial cells with collagen induces separation of the cells, changes in morphology, and reinitiation of growth. These shape changes do not require protein synthesis, appear to be independent of fibronectin, are not inhibited by cytochalasin D, but are inhibited by colchicine. Endothelial cell growth can be reinitiated by collagen. This phenomenon appears to be related to a change in cell shape and perhaps to separation of cells at the intercellular junction. In contrast, smooth muscle cells plated on collagen infiltrate the gels and assume a spindle-like, elongated morphologic appearance. Overlayment with collagen does not alter smooth muscle cell shape. Migration into the collagen gels is significantly enhanced when cells are cultured in medium containing platelet-released products, independent of growth stimulation itself. Migration is accompanied by collagen gel degradation. Release of labeled collagen into the medium by smooth muscle cells and appearance of TCA fragments in collagenase assay suggest secretion of collagenase. In summary, endothelial cells, but not smooth muscle cells, are restricted to the surface of collagen gels. The ability of the smooth muscle cells to invade is stimulated by platelet products and may be related to the synthesis of a smooth muscle collagenase.
Animals↗
Intensification of remission induction therapy for acute nonlymphocytic leukemia (ANLL). I. Response and toxicity in four different regimens.
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Acute Disease↗
[Influence of ribose on 2,3-diphosphoglycerate concentrations in human erythrocytes].
The effect of ribose on the 2,3-diphosphoglycerate concentration (2,3-DPG) of human red blood cells was investigated and compared to the effect of inosine. Ribose as well as inosine increases 2,3-DPG. Most impressing effects can be demonstrated on stored blood, which is poor in 2,3-DPG concentration. Physiologic 2,3-DPG-concentrations, however, may be increased too. Generally the effect of inosine is greater than the effect of ribose. When ribose is applicated intravenously a slight increase in 2,3-DPG is found. Both compounds own characteristic side-effects, which diminish their value for therapeutical purposes.
Diphosphoglyceric Acids↗
Effect of bilirubin on stored red blood cells.
Bilirubin may cause haemolysis of red cells, especially in the presence of light. The possible dependence of this effect on the metabolic state of the cells has been investigated. For this purpose erythrocytes were stored up to five days to deplete the concentration of ATP. Every day a constant amount of bilirubin was added to the cells. On third day of storage bilirubin induced haemolysis, which was aggravated rapidly during further storage. Bilirubin-induced haemolysis could be reduced after increasing the ATP levels by incubation of the red cells with inosine.
Adenosine Triphosphate↗
The mechanism of fibrin-induced disorganization of cultured human endothelial cell monolayers.
Deposition of polymerizing fibrin on the vascular endothelium is the final event in intravascular coagulation. Exposure of fibrin clots to confluent monolayers of cultured human endothelial cells for 4 to 24 hours resulted in the disappearance of their normal cobblestone morphology and in the formation of endothelial cell aggregates. The present study was designed to evaluate the conditions and structural requirements of the fibrin clot for the induction of disorganization. Even after harsh treatment with denaturing agents or loading with large amounts of fibrinogen antibodies, polymerized fibrin always induced disorganization of the monolayers. In contrast, soluble fibrin that was kept in solution by either fibrinogen, fragment D-cate, or the tetrapeptide Gly-Pro-Arg-Pro did not cause any alteration of the monolayers. The fibrinogen degradation product D-cate (Mr 94,000) itself had no microscopically detectable influence on the monolayer structure. In the absence of fibrin, the effect of thrombin on endothelial cells was found to be distinct from that induced by fibrin; however, the exposure of pieces of glass coverslips caused alterations in morphology indistinguishable from the fibrin-induced disorganization of the monolayer. Experiments using protein-coated polyester films indicated that the ability of the endothelial cells to attach to the overlying material, independent of its chemical structure, is the prerequisite for the induction of disorganization, but not a defined component of the fibrin molecule. Disorganization of vascular endothelium in vivo might be important for the organization and revascularization of an occluding thrombus.
Collagen↗
A regimen for antithrombin III substitution in patients with acute lymphoblastic leukemia under treatment with L-asparaginase.
BACKGROUND AND METHODS: Seventeen adult patients with acute lymphoblastic leukemia (ALL) treated with L-asparaginase (20,000 IU/m2 on six alternate days) were infused with antithrombin III (AT III) concentrates (Kybernin P, Behring). Substitution therapy was aimed at increasing the reduced AT III concentration usually found in these patients, since AT III deficiency is thought to be associated with an increased risk of thrombosis. Two schedules of AT III administration, different in dosage, timing and duration were evaluated. The first 7 patients (group A) received a fixed dose of 2,000 U every day for 6 times, starting with the second L-asparaginase (L-ase) infusion, independently of their plasma AT III levels. In the following 10 patients (group B), 20-25 U/Kg b.w. were administered daily for 7 times only when the plasma AT III level was lower than 60% with plasma fibrinogen higher than 100 mg/dl and platelet count higher than 50 x 10(9)/l, or when AT III was below 40%. Thirteen patients who received L-ase without AT III substitution served as controls. RESULTS AND CONCLUSIONS: Both substitution regimens resulted in mean plasma AT III nadir values significantly (p less than 00.1) higher than in the controls. Our data suggest that, in ALL patients receiving L-ase according to the L20 protocol, satisfactory plasma AT III levels may be assured with infusions of 20-25 U/Kg b.w./day for 7-10 days, starting by day 2 of L-ase treatment.
Adult↗