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Query: UMLS:C0001511 (Adhesion)
 5,955 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

When exposed to thrombin, the adhesion of platelets to a von Willebrand factor (vWf) substrate, relative to a control substrate, is selectively increased. Adhesion to a vWf substrate is dependent upon the concentration of vWf, the duration of the adhesion assay, the concentration of thrombin, and the presence of divalent cations. The enhanced adhesion results from an action of thrombin on the platelets; no effect on the vWf substrate is involved. Once adherent to the substrate, the platelets undergo a profound change in morphology from the spiny sphere phenotype characteristic of activated platelets to a flattened and highly spread state. The adhesion of activated platelets to solid phase vWf is not inhibited by physiological concentrations of fibrinogen.
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PMID:Thrombin enhanced adhesion of platelets to von Willebrand factor substrates. 301 79

A procedure is presented allowing detailed studies of the adsorption of coagulation factors from whole blood on to surface. Anticoagulant (citrate or hirudin) was added to fresh venous blood. The blood was incubated in hydrophilic or hydrophobic glass tubes without contact with air. The adsorption of fibrinogen, fibronectin and factor IX was measured with an enzyme immunoassay using specific antibodies directed against these proteins. Adsorption of enzymically active kallikrein was measured using a chromogenic peptide substrate. Adhesion and activation of platelets was measured by direct examination in a scanning electron microscope and by measurement of release of beta-thromboglobulin. The results show that the adsorption of plasma proteins at the blood-solid interface is dependent on the anticoagulant used, surface energy of the test surface and incubation time. In experiments using hirudin a specific inactivator of thrombin, as anticoagulant, we found dynamic changes of the adsorbed protein film which could not be studied using citrated blood.
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PMID:Adsorption of coagulation proteins and adhesion and activation of platelets at the blood-solid interface. An experimental study of human whole blood. 322 38

Platelets adhere to vitronectin substrate following activation with physiological concentrations of thrombin. Adhesion of activated platelets to vitronectin substrate is dependent upon the presence of divalent cations, the amount of vitronectin, and the duration of adhesion assay. The adhesion of platelets is inhibited by synthetic peptides containing the sequence of Arg-Gly-Asp. In addition, monoclonal antibodies to glycoprotein IIb-IIIa complex inhibit the adhesion of activated platelets to vitronectin substrate in a dose-dependent manner. These studies suggest that the glycoprotein IIb-IIIa complex on activated platelets may interact with vitronectin substrate through the Arg-Gly-Asp mechanism. Since vitronectin is present in the subendothelial matrix, it might be involved in platelet-vessel wall interactions.
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PMID:Interaction of thrombin-stimulated platelets with vitronectin (S-protein of complement) substrate: inhibition by a monoclonal antibody to glycoprotein IIb-IIIa complex. 323 53

The purpose of this study was to examine the influence of substances released from human platelets upon their accumulation on human fibrinogen-coated glass tubes. After prestimulation with thrombin for one minute or in the absence of prestimulation, washed human platelets suspended in Eagle's medium with RBC were drawn through the tubes at 1 ml/min, 80 s-1, for 1, 2 or 6 min. Thrombin prestimulation (0.02, 0.05 or 0.25 U/ml) was followed by inactivation with hirudin (0.1, 0.25 or 1.25 U/ml) before flow. Singly adherent platelets were observed in the absence of thrombin or with thrombin for exposure times of 1 and 2 min. At 6 min after at least 0.05 U/ml of thrombin, surface-bound aggregates were observed. The initial rate of adhesion increased with the amount of thrombin used for prestimulation. For adhesion to fibrinogen in the absence of prestimulation, platelet-derived ADP was a stimulator. Adhesion was shown to be independent of the ADP and arachidonic acid pathways in response to prestimulation with a low level of thrombin, 0.02 U/ml. For adhesion and cohesion, aggregation, in the presence of sufficient thrombin for prestimulation, 0.05 U/ml, ADP, serotonin and substances from arachidonic acid metabolism acted jointly to stimulate platelets.
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PMID:Adhesion and aggregation of thrombin prestimulated human platelets on surface-bound fibrinogen: evidence for involvement of ADP and arachidonic acid pathways. 641 17

Human Factor VIII associated von Willebrand factor (VIII:vWF) binds to human platelets in vitro only in the presence of a mediator such as ristocetin, thrombin or ADP. Studies reported here were designed to determine if human platelets will adhere to solid-phase VIII:vWF. Human VIII:vWF was purified from a phosphate precipitate of A1(OH)3 absorbed plasma using 4% agarose and DEAE cellulose. Purified VIII:vWF (90 units of VIII:vWF activity/mg) was coated on dialysis membranes using ultrafiltration (final concentration of 0.4 units/cm2). Membranes (0.5 cm2) were held stationary in human citrated PRP suspension or washed platelet suspensions and stirred continuously for 5 minutes at 37 degrees C. The membranes were then rinsed in phosphate buffered saline, fixed, stained, and examined by light and scanning electron microscopy. Abundant normal platelets adhered to VIII:vWF-coated membranes, while minimal adhesion was seen on uncoated membranes and membranes coated with albumin. Adhesion occurred without ristocetin, thrombin, ADP or other agonist and in the presence of Ca+2/Mg+2 ions. Preincubation of the VIII:vWF coated membranes with monospecific rabbit anti-VIII:vWF inhibited the adhesion reaction. However, preincubation of VIII:vWF coated membranes with naturally occurring human anti-FVIIIc antibodies failed to interfere with platelet adhesion. Platelets from a patient with Bernard-Soulier Syndrome (BSS) which did not bind human VIII:vWF in the presence of ristocetin or aggregate with bovine cryoprecipitate also did not adhere to VIII:vWF-coated membranes.
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PMID:Adhesion of human platelets to purified solid-phase von Willebrand factor: studies of normal and Bernard-Soulier platelets. 641 73

Heparin inhibited monolayer adhesion of washed human and rabbit platelets to collagen-coated glass at 2.5 and 20 units/ml concentration, in the absence of red cells. Adhesion of rabbit platelets to de-endothelialized rabbit aorta, under similar conditions, was less strongly inhibited but no inhibition was seen at 40% haematocrit. Addition of plasma reduced, rather than enhanced heparin activity and hirudin 0.5 units/ml had no significant effect. Heparin also inhibited platelet aggregation, release of (14C) 5-HT and production of malondialdehyde in response to collagen and thrombin. Inhibition of thrombin-induced activity was greater in the presence of plasma. However, heparin enhanced aggregation and release evoked by ADP and did not consistently inhibit MDA synthesis produced by arachidonate. The results indicate that in addition to the effects of heparin on platelet function mediated by anti-thrombin activity and the previously described augmentation of responses to ADP, heparin has weak inhibitory activity against platelet-collagen interactions. Binding of heparin to the platelet membrane (and to surfaces to which platelets adhere) could account for these findings by causing non-specific interference with agonist-receptor interactions.
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PMID:Effect of heparin on platelet monolayer adhesion, aggregation and production of malondialdehyde. 710 Dec 45

A comparative study of leukocyte adhesion to the endothelium of the thoracic aorta and left carotid artery in rats has been performed after administration of two hyperlipidemic diets for 15 days, proinflammatory agents (thrombin, lipopolysaccharide and zymosan activated serum) and plasma expanders [dextran, polyvinylpyrrolidone (PVP), rat albumin and several bovine albumins from different sources]. Leukocytes adhered to the endothelium were demonstrated in surface preparations by esterase activity. Activation of circulating leukocytes was measured by nitroblue tetrazolium reduction and luminol enhanced chemiluminescence. Both hyperlipidemic diets produced, in all rats, more leukocyte adhesion in the aorta than in the carotid artery. All proinflammatory agents produced at 1 h, increases in leukocyte adhesion--which in all rats were greater in the carotid artery than in the aorta--and leukocyte activation, which was higher at 3 h than at 1 h. Dextran, PVP, bovine albumins 103700 and A-4503 at 18 h produced slight increases in leukocyte adhesion in the aorta but not in the carotid artery. Rat albumin and bovine albumin A-7906 determined an intense leukocyte adhesion at 18 h which was not preferential to either vessel. Adhesion produced by A-7906 was maximal at 12 h and partially inhibited by dexamethasone. This last albumin produced leukocyte activation at 3 h and was sequestered 5 min after administration, reaching normal values at 1 h. Albumins 103700 and A-4503 neither activated leukocytes nor were sequestered after administration.
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PMID:Effect of hyperlipidemic diets, proinflammatory agents and plasma expanders on leukocyte adhesion to the endothelium of aorta and carotid artery of rats. 753 42

Platelet-activating factor (PAF) is known to modulate polymorphonuclear leukocyte (PMN) adhesion to endothelial cells cultured under static conditions and activated by thrombin. In contrast, there are no data on the role of PAF in PMN adhesion to cells exposed to flow conditions and activated by stimuli other than thrombin. Here we used the PAF receptor antagonist L-659,989 to evaluate PMN adhesion to human umbilical vein endothelial cells (HUVEC) in basal conditions or upon challenge with thrombin or tumor necrosis factor-alpha (TNF-alpha). Experiments were performed under dynamic flow using a parallel-plate flow chamber and a computer-based image analysis system. Rolling and adhesion of PMNs to endothelial cells significantly increased upon stimulation with thrombin. Thrombin-stimulated HUVEC also synthesized higher amounts of PAF than untreated cells. Pretreatment of PMNs with L-659,989 significantly reduced their rolling and adhesion to thrombin-activated HUVEC. Stimulation of HUVEC with TNF-alpha significantly increased the number of rolling and adherent PMNs as compared with untreated cells. Adhesion of PMNs to and migration across TNF-alpha-stimulated HUVEC were reduced by L-659,989, whereas cell rolling was unchanged. We conclude that PAF mediates leukocyte interaction under flow conditions with HUVEC activated by inflammatory stimuli.
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PMID:PAF mediates neutrophil adhesion to thrombin or TNF-stimulated endothelial cells under shear stress. 763 59

Magnesium deficiency and its association with platelet hyperreactivity has been well recognised in a variety of diseases including myocardial infarction, preeclampsia, and diabetes. In order to investigate potential effects of intravenous Mg2+ supplementation, platelet function was studied by measurements of in vitro bleeding time (BT) and of fibrinogen (Fg)-mediated aggregation of washed platelets. In addition, the effect of Mg2+ on platelet adhesion onto immobilised Fg, on Fg binding to activated platelets, and on surface expression of GMP-140 or GP53 was evaluated. Mg2+ (4 mM) prolonged in vitro BT by 30% and inhibited Fg-mediated aggregation significantly, independent of the agonist used to initiate platelet aggregation (ADP, collagen, epinephrine, thrombin, phorbol ester). Adhesion of resting platelets to immobilised Fg was reduced by 50% in the presence of 2 mM Mg2+. Moreover, Mg2+ reduced Fg binding to ADP- or collagen-stimulated platelets as well as surface expression of GMP-140 with an IC50 of approximately 3 mM. Intravenous administration of Mg2+ to healthy volunteers inhibited both ADP-induced platelet aggregation (p < 0.05) by 40% and binding of Fg or surface expression of GMP-140 by 30% (p < 0.05). Thus, pharmacological concentrations of Mg2+ effectively inhibit platelet function in vitro and ex vivo.
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PMID:Effects of magnesium on platelet aggregation and adhesion. Magnesium modulates surface expression of glycoproteins on platelets in vitro and ex vivo. 774 Apr 63

Endothelial damage, synovial oedema, fibrin deposition, polymorphonuclear cell (PMN) invasion, and mild lining cell hyperplasia characterize acute inflammatory arthritis. Later on, perivascular tissue is infiltrated by mononuclear cells. The early events are mediated by interactions between PMNs and endothelial cells. Both parts in the adhesion event are activated with multiple stimuli resulting in complex interactions of varying intensity and duration. Adhesion molecules present on the surface of PMNs (L-selectin) or induced by inflammatory stimuli (beta 2-integrins) mediate PMN adhesion to activated endothelium, which has counter receptors (E-selectin for L-selectin and ICAM-1 and ICAM-2 for beta 2-integrins). At the initial phase L-selectin initiates the rolling of PMNs on endothelial cells. Further stimuli result in a more prolonged adhesion between PMNs and endothelium. At the side of endothelium, induction of P-selectin and PAF by histamine, thrombin and LTC4 contribute to the acute rolling of PMNs on endothelial surface. Tumor necrosis factor (TNF), interleukin-1 (IL-1) and lipopolysaccharide activate endothelial cells to synthesize interleukin-8 (IL-8), a potent chemotactic and proadhesive mediator for PMNs, and further adhesion molecule (E-selectin), a mediator of long-term adhesion between PMN and endothelium. After adhesion and migration to the focus of inflammation, PMNs induce inflammation by aggregating, releasing hydrolyzing enzymes, generating lipid peroxidation products such as prostaglandins and LTB4, and oxygen derived free radicals. In studies on the pathogenesis of seronegative spondyloarthropathies, we have shown persistently aberrant PMN function evidenced by enhanced chemotaxis and high production of toxic oxygen derived free radicals by PMN.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The present knowledge of the inflammatory process and the inflammatory mediators. 781 74


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