[Study of cryoglobulin associated with no retraction of clot in multiple myeloma].
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Requirements for alpha(5)beta(1) integrin-mediated retraction of fibronectin-fibrin matrices.
Retraction of the blood clot by nucleated cells contributes both to hemostasis and to tissue remodeling. Although plasma fibronectin (FN) is a key component of the clot, its role in clot retraction is unclear. In this report, we demonstrate that the incorporation of FN into fibrin matrices significantly improves clot retraction by nucleated cells expressing the integrin alpha(5)beta(1). Further, we show that FN-fibrin clots support increased cell spreading when compared with fibrin matrices. To determine the structural requirements for FN in this process, recombinant FN monomers deficient in ligand binding or fibrin cross-linking were incorporated into fibrin clots. We show that recombinant FN monomers support clot retraction by Chinese hamster ovary cells expressing the integrin alpha(5)beta(1). This process depends on both the Arg-Gly-Asp (RGD) and the synergy cell-binding sites and on covalent FN-fibrin binding, demonstrating that cross-linking within the clot is important for cell-FN interactions. These data show that alpha(5)beta(1) can bind to FN within a clot to promote clot retraction and support cell shape change. This provides strong evidence that alpha(5)beta(1)-FN interactions may contribute to the cellular events required for wound contraction.
Animals↗
Lymphokines and thrombosis. I. Thrombocyte aggregating activity released by human lymphocytes stimulated with concanavalin-A.
Supernatants from Con-A stimulated human lymphocytes containing leucocyte migration inhibitory activity were measured for thrombocyte aggregation activity and for influence on thrombocyte rich plasma clot retraction and whole blood clot retraction. The lymphocyte released activity of the supernatants produced thrombocyte aggregation and an acceleration of clot retraction. The activity resisted heating at 56 degrees C for 30 min and was inactivated at 80 degrees C for 30 min. The active substance seems to have a molecular weight above 10,000 daltons. The findings suggest that thrombotic processes associated with cell-mediated (type IV) immune inflammation could be due, at least partially, to lymphokine effects on thrombocytes.
Blood Platelets↗
Biochemical and biophysical conditions for blood clot lysis.
We have studied how pharmacological dissolution of blood clots was affected by clot retraction, the mode of transport of fibrinolytic agents into the clot and the thickness of the composite fibrin fibers. Retracted clots were resistant to fibrinolysis in a milieu without dissolved plasminogen, because the amount of fibrin-bound plasminogen in retracted clots was insufficient for successful clot lysis. In plasma containing plasminogen, retracted clots were successfully lysed with fibrin-specific plasminogen activators, but not with non-fibrin-specific activators. Preincubation of retracted clots in plasma increased their plasminogen content as well as their sensitivity to fibrinolysis. The rate of lysis was increased up to 100-times when plasminogen activator and plasminogen were introduced into cylindrical clots by pressure-induced bulk flow in comparison with diffusion alone. The magnitude of the increase was similar in retracted and nonretracted clots, but the absolute rate of lysis was faster in non-retracted clots. The influence of fibrin fiber thickness on fibrinolysis was studied by atomic force microscopy. The time to complete lateral section of fibers did not differ between thick and thin composite fibers, and the rate of diameter reduction was faster in thick fibers than in thin ones. Taken together our results suggest that lysis of retracted clots proceeds in circular stages: (a) activation of bound plasminogen followed by partial degradation of fibrin, (b) opening of new plasminogen-binding sites on partly degraded fibrin, (c) binding of plasminogen to the new binding sites which enhances the susceptibility of clots to lysis. Lysis is accelerated by bulk flow of plasminogen activator and plasminogen into clots in comparison to diffusion alone. Fibrinolysis of thick composite fibrin fibers proceeds more efficiently than lysis of thin fibers.
Biophysical Phenomena↗
Stabilization of platelet-fibrinogen interactions: modulation by divalent cations.
The binding of fibrinogen to its GPIIb-IIIa receptor is divalent-cation dependent. In addition to Ca+2 and Mg+2, Mn+2 has been shown to modulate adhesive protein interactions with integrins. This study examined the effect of Mn+2 on fibrinogen interactions with intact platelets. Compared with that of control platelets in buffer containing 1 mmol/L Mg+2, fibrinogen binding to adenosine diphosphate- or thrombin-stimulated platelets decreased 23% +/- 12% and 15% +/- 9% (mean +/- SD, n = 4), respectively, after addition of 1 mmol/L Mn+2. No change in binding affinity was noted, but the stability of platelet-fibrinogen interactions was diminished markedly. Ethylenediaminetetraacetic acid dissociated 68% +/- 8% of fibrinogen bound to ADP-treated platelets (p < 0.05) during a 60-minute incubation with fibrinogen and 1 mmol/L Mn+2, compared with 40% +/- 13% of fibrinogen bound to control platelets and 29% +/- 8% of fibrinogen bound in the presence of Ca+2 (mean +/- SD, n = 6). Mn+2 also diminished the stabilization of fibrinogen interaction with thrombin-stimulated platelets and inhibited the recovery of bound fibrinogen with the Triton X-100 (Union Carbide Corp., Danbury, Conn.) insoluble cytoskeleton. Only 31% +/- 10% of fibrinogen bound to thrombin-stimulated platelets for 60 minutes in the presence of Mn+2 associated with the cytoskeleton (p < 0.05), compared with 61% +/- 14% and 75% +/- 20% of fibrinogen bound to control platelets incubated with and without Ca+2, respectively. Mn+2 further inhibited large adenosine diphosphate- or thrombin-induced platelet aggregate formation and reduced the ability of platelets to retract fibrin clots. These data suggest that Mn+2 alters GPIIb-IIIa function relative to native fibrinogen and support a role for the stabilization of platelet-fibrinogen interactions in platelet aggregation and clot retraction.
Adenosine Diphosphate↗
An in vitro test of platelet viability.
The survival of transfused platelets is inversely related to the time of storage of platelets in vitro. The effects of storage on the ability of platelets to produce retraction of clots and on the morphologic alterations of platelets within the clots has been studied. The results suggest that clot retraction, using low concentrations of platelets, may be useful as an in vitro method for evaluating the viability of platelets.
Blood Platelets↗
Active GPIIb-IIIa conformations that link ligand interaction with cytoskeletal reorganization.
Glycoprotein (GP) IIb-IIIa plays a critical role in platelet aggregation and platelet-mediated clot retraction. This study examined the intramolecular relationship between GPIIb-IIIa activation and fibrinogen binding, platelet aggregation, and platelet-mediated clot retraction. To distinguish between different high-affinity activation states of GPIIb-IIIa, the properties of an antibody (D3) specific for GPIIIa that induces GPIIb-IIIa binding to adhesive protein molecules and yet completely inhibits clot retraction were used. Clot retraction inhibition by D3 was not due to altered platelet-fibrin interaction; however, combination treatments of D3 and adenosine diphosphate (ADP) inhibited full-scale aggregation and decreased the amounts of GPIIb-IIIa and talin incorporated into the core cytoskeletons. Morphologic evaluation of the D3/ADP aggregates showed platelets that were activated but to a lesser extent when compared to ADP only. ADP addition to platelets caused an increase in the number of D3 binding sites indicating that ligand had bound to the GPIIb-IIIa receptor. These data suggest that high-affinity GPIIb-IIIa- mediated ligand binding can be separated mechanistically from GPIIb-IIIa-mediated clot retraction and that clot retraction requires additional signaling through GPIIb-IIIa after ligand binding. The conformation recognized by D3 represents the expression of a GPIIb-IIIa activation state that participates in full-scale platelet aggregation, cytoskeletal reorganization, and clot retraction.
Adenosine Diphosphate↗
Serum anti-platelet activity in acute leukemias (AL) and chronic thrombocytopenic purpura (ITP).
Serum anti-platelet activity in 44 patients with acute leukemia (AL), 19 patients with idiopathic thrombocytopenic purpura (ITP) and 30 healthy controls was studied by using the platelet factor 3 availability test (PF-3) and the inhibition test of clot retraction. Shortening of the clotting time in PF-3 test performed with isologous platelets was found in 30 of 44 cases as a result of accelerating the intrinsic coagulation pathway. During AL remission in 6 examined cases an effect of this serum activity on autologous platelets was demonstrated. Serum anti-platelet activity was inhibited by rabbit anti-IgG. The obtained results suggest that the activity present in the globulin fraction of AL patients serum may contribute to thrombocytopenia in this disease. The influence of various concentrations and combinations of cytostatics on PF-3 and the inhibition of clot retraction tests were examined in vitro. Out of vincristine, methotrexate, cytosine arabinoside and cerubidine only the combination of cytosine arabinoside and vincristine caused the clotting time in the PF-3 test to be shortened. As a single drug only methotrexate caused an inhibition of clot retraction.
Acute Disease↗
Platelet thrombosthenin: subcellular localization and function.
Thrombosthenin, an immunologically distinct contractile protein was isolated in relatively pure form from human platelets. The protein, which was of high molecular weight appeared to be composed of multiple polypeptide subunits, probably polymeric in nature.Thrombosthenin had magnesium-dependent ATPase activisty, releasing an average of 3 mug phosphorus per mg protein in 30 min. After the addition of ATP, there was a reversible alteration in viscosity with calculated ATP sensitivity ranging from 64 to 90%. These biochemical properties of thrombosthenin resemble those of smooth muscle.Specific antisera to thrombosthenin significantly inhibited the ATPase activity of the protein. Clot retraction of recalcified platelet-rich plasma and clot retraction of clotted fibrinogen-platelet mixtures were also inhibited by the antisera. The findings suggest that thrombosthenin is an important component of the clot retraction system.Thrombosthenin was extracted from isolated platelet granule and membrane fractions. The contractile protein derived from the membrane compartment was more active as an ATPase and appeared to be more homogeneous on immunologic analysis.
Journal Article↗
The nonoperative treatment of massive pyloroduodenal hemorrhage by retracted autologous clot embolization.
Six patients with massive pyloroduodenal hemorrhage were treated by selective embolization of retracted autologous clot to occlude the bleeding vessels. All patients had severe associated illnesses and were very poor candidates for operative treatment. The actively bleeding vessel was occluded successfully and hemorrhage was controlled with autologous clot alone in five of these patients, although two patients later bled from other sites. Although three patients died, none died as a direct result of bleeding. The only complication encountered, multiple small hepatic infarct, occurred when the embolized clot migrated from the gastroduodenal artery to the hepatic artery. A method of avoiding this complication is presented. Selective emolization of retracted autologous clot represents a useful alternative to the operative management of massive pyloroduodenal hemorrhage and should be considered for the treatment of patients whose associated diseases make them poor candidates for operative treatment.
Adult↗
Activation of platelet-rich plasma using thrombin receptor agonist peptide.
PURPOSE: This study proposes an alternative preparation method of platelet-rich plasma (PRP). Specifically, we compare the use of thrombin receptor agonist peptide-6 (TRAP) and bovine thrombin as a clotting agent in the preparation of PRP. MATERIALS AND METHODS: PRP was prepared by centrifugation and clotted with thrombin or TRAP. In vitro clotting times were monitored as a function of TRAP concentration, and clot retraction was determined by measuring clot diameter over time. Following the optimization of TRAP concentration, experiments were repeated with the addition of several commercially available bone substitutes. The release of PRP-relevant growth factors as a function of PRP preparation was also determined. RESULTS: The most rapid polymerization of PRP takes place with the addition of thrombin, followed by TRAP/Allogro (Ceramed, Lakewood, CO), TRAP/BioGlass (Mo-Sci, Rolla, MN), TRAP/BioOss (Osteohealth, Shirley, NY), and TRAP alone. Thrombin caused considerable clot retraction (43%), whereas TRAP alone resulted in only 15% retraction. TRAP/Allogro, TRAP/BioOss, and TRAP/BioGlass all exhibited minimal retraction (8%). CONCLUSIONS: The use of TRAP to activate clot formation in the preparation of PRP may be a safe alternative to bovine thrombin. It results in an excellent working time and significantly less clot retraction than the currently available methods of PRP production.
Analysis of Variance↗
Phenylmercuric acetate and some hemostatic activities of rat platelets.
Fungicide, phenylmercuric acetate (PMA) dose-dependently inhibits in vitro ADP-induced rat platelet primary aggregation. During ex vivo experiments, after oral application of different doses of PMA, the ADP-induced aggregation, clot retraction, bleeding time and clotting time were estimated. Inhibition of platelet activity was found only after a single administration with the high dose of PMA (0.5 LD50). Administration to the rats five times a low dose of PMA (0.2 LD50) and exposure during 5 weeks to the dose of 0.05 LD50 produced hypercoagulation (statistically significant reduction of clotting time) with simultaneous stimulation of platelet activity (stimulation of aggregation, clot retraction and shortening of bleeding time).
Adenosine Diphosphate↗
Involvement of alpha v beta 3 integrin in mediating fibrin gel retraction.
Platelet integrin alpha IIb beta 3 (GPIIb-IIIa) plays important roles in platelet-mediated clot retraction. However, little is known about the mechanisms of clot retraction mediated by nucleated cells. In this report, we demonstrate that another member of the beta 3 integrin family, alpha v beta 3, is involved in clot retraction mediated by nucleated cells. Retraction of fibrin clots was observed using a human melanoma cell line, C32TG, which contains no alpha IIb beta 3 complex. This retraction was inhibited by RGD-containing peptide, monoclonal anti-beta 3, and anti-alpha v beta 3 antibodies. Immunoelectron microscopic studies revealed a direct interaction between beta 3 integrin and fibrin fibers at an early stage of clot retraction. We found that another human embryonal cell line, 293, which is known to express alpha v beta 1, but no alpha v beta 3, lacks fibrin gel retractile activity. Upon transfection of beta 3 DNA into 293 cells, the beta 3 subunit formed a complex with an endogenous alpha v subunit. The beta 3-bearing transfectants were found to retract fibrin gels, which was specifically inhibited by anti-beta 3 antibody. In addition, a point mutation at Asp119 in the beta 3 ligand binding domain abolished the clot retractile activity of 293 transfectants, indicating the requirement of alpha v beta 3 ligand-binding activity. Our findings suggest that alpha v beta 3 is involved in mediating the interaction between the three-dimensional fibrin network and nucleated cells and in promoting "post-receptor occupancy" events.
Antibodies, Monoclonal↗
ClfA(221-550), a fibrinogen-binding segment of Staphylococcus aureus clumping factor A, disrupts fibrinogen function.
Clumping factor A (ClfA) is a surface protein of Staphylococcus aureus bacteria known for its ability to bind the C-terminus of plasma fibrinogen gamma chain, which participates in mediating fibrinogen-platelet interaction and fibrin cross-linking, resulting in thrombus formation. With an aim to develop agents that block fibrinogen gamma chain C-terminus, the fibrinogen-binding segment of ClfA locating at residues 221-550 was produced by recombinant technology and tested for its ability to inhibit platelet functions and fibrin clot formation. Recombinant ClfA(221-550) bound fibrinogen and blocked fibrinogen-platelet interaction, resulting in the inhibition of both ADP- and collagen-induced platelet aggregations. ClfA(221-550) also affected fibrin clot formation, in which factor XIIIa-mediated cross-linking of fibrinogen gamma chains was abrogated by ClfA(221-550) leaving the release of fibrinopeptides A and B from fibrinogen by thrombin unaltered, indicating that ClfA(221-550) interfered with fibrin clot formation without affecting thrombin's catalytic activity. Platelet-mediated clot retraction depends on both platelet-fibrinogen interaction and fibrin clot formation, which makes platelet thrombus less susceptible to fibrinolysis. At the concentration that reduced platelet aggregation by 40%, ClfA(221-550) prevented platelet-mediated clot retraction, whereas the glycoprotein IIb/IIIa antagonist tirofiban needed a higher concentration in inhibiting clot retraction than inhibiting platelet aggregation. By virtue of the multiple effects of ClfA(221-550) on platelet aggregation, fibrin clot formation and platelet-mediated clot retraction, the binding of ClfA(221-550) to fibrinogen merits further investigation for its potential as a new antithrombotic agent.
Adenosine Diphosphate↗
Platelet factor 3 in normal subjects and patients with renal failure.
Two tests were used to differentiate abnormalities in release of platelet factor 3 (PF3) from quantitative deficiencies of this factor in normal subjects and in patients with renal failure. The first test was an assay which determined availability of PF3 (PF3-A time) and involved the use of a mixture of patient's platelet-rich plasma (PRP) and normal platelet-poor plasma (PPP) in a fixed ratio (1:8). The second test was similar but used "frozen and thawed" platelets to obtain a quantitative estimate of PF3 (PF3-F time). An abnormal PF3-A time was found in approximately three-quarters of 55 patients with renal insufficiency; 43 of these had chronic and 12 had acute renal failure. This abnormality was present both in patients with and without hemorrhagic manifestations, although it was slightly more common in bleeders. The PF3-F test was abnormal in approximately one-third of the bleeding patients and one-quarter of the non-bleeders. The PF3-A time returned to normal or was significantly shortened 24-48 hr after peritoneal or hemodialysis. Studies on patients who were not dialyzed showed no statistically significant correlations between the PF3-A time and either the serum urea nitrogen, creatinine, calcium, or phosphorus. Furthermore, the PF3-A time was not affected by guanidinosuccinic or guanidinoacetic acids. We therefore conclude that the demonstrable platelet abnormality in patients with uremia is produced by an unknown dialyzable material. The mean plasma clot retraction of uremic patients was also significantly different from the mean plasma clot retraction or normal controls. However, unlike the PF3-A time, the abnormality of plasma clot retraction was not immediately affected by dialysis. Correction of plasma clot retraction did occur after repeated dialyses.
Acute Kidney Injury↗
Identification of a novel binding site for platelet integrins alpha IIb beta 3 (GPIIbIIIa) and alpha 5 beta 1 in the gamma C-domain of fibrinogen.
The interactions of platelets with fibrinogen mediate a variety of responses including adhesion, platelet aggregation, and fibrin clot retraction. Whereas it was assumed that interactions of the platelet integrin alpha IIb beta 3 with the AGDV sequence in the gamma C-domain of fibrinogen and/or RGD sites in the A alpha chains are involved in clot retraction and adhesion, recent data demonstrated that fibrinogen lacking these sites still supported clot retraction. These findings suggested that an unknown site in fibrinogen and/or other integrins participate in clot retraction. Here we have identified a sequence within gamma C that mediates binding of fibrinogen to platelets. Synthetic peptide duplicating the 365-383 sequence in gamma C, designated P3, efficiently inhibited clot retraction in a dose-dependent manner. Furthermore, P3 supported platelet adhesion and was an effective inhibitor of platelet adhesion to fibrinogen fragments. Analysis of overlapping peptides spanning P3 and mutant recombinant gamma C-domains demonstrated that the P3 activity is contained primarily within gamma 370-383. Integrins alpha IIb beta 3 and alpha 5 beta 1 were implicated in recognition of P3, since platelet adhesion to the peptide was blocked by function-blocking monoclonal antibodies against these receptors. Direct evidence that alpha IIb beta 3 and alpha 5 beta 1 bind P3 was obtained by selective capture of these integrins from platelet lysates using a P3 affinity matrix. Thus, these data suggest that the P3 sequence in the gamma C-domain of fibrinogen defines a previously unknown recognition specificity of alpha IIb beta 3 and alpha 5 beta 1 and may function as a binding site for these integrins.
Amino Acid Sequence↗
Spontaneous inhibitors to coagulation factors.
Spontaneous inhibitors to coagulation factors are autoantibodies that usually appear in the elderly, but may also occur in patients with immunological disorders such as lupus, lymphoma, asthma or drug reactions. Most antibodies are directed against factor VIII, but any coagulation protein may be affected. They should be suspected in individuals who previously had normal haemostasis, but who now begin to experience bleeding into the skin and muscles, or suffer haemorrhages after routine procedures such as insertion of vascular catheters, intramuscular injections, or minor surgery. The haemostasis laboratory is critical in identifying the particular inhibitor and quantitating its potency. Factor VIII inhibitors prolong the partial thromboplastin time (PTT) but not the prothrombin time (PT), and incubating mixtures of patient plasma and normal plasma enhances the prolongation of the clotting time. The Bethesda assay provides a rough assessment of inhibitor potency. Inhibitors of von Willebrand factor prolong the bleeding time and impair ristocetin-induced platelet aggregation. Factor V inhibitors are associated with a prolonged PTT and PT, not correctable with normal plasma. Patients will often have a history of exposure to bovine thrombin in fibrin glue. The antibodies most difficult to recognize are those that alter fibrin polymerization or stabilization. Abnormal clot retraction or clot solubility in urea solutions are an important clue. The management of these disorders depends on characterization of the inhibitor, and using appropriate clotting factor concentrates to control acute bleeding. For example, recombinant human factor VIII or desmopressin may be effective for patients with low titre factor VIII inhibitors, whereas porcine factor VIII, recombinant factor Vlla, or prothrombin complex concentrates stem bleeding in those with high titres. Inhibitors of von Willebrand factor may be amenable to desmopressin, cryoprecipitate, or von Willebrand factor concentrates. Some patients with factor V inhibitors have responded to platelet transfusions, as the platelet factor V may be shielded from the autoantibody. Bleeding due to factor XIII inhibitors may be managed with fibrogammin, a factor XIII concentrate. All patients should be treated for underlying disorders and given drugs such as corticosteroids and cytotoxic agents to suppress inhibitor formation. Major advances in new immunosuppressive technologies, such as monoclonal B-cell antibodies, offer hope of more effective therapies for spontaneous inhibitors to coagulation factors.
Adult↗
[Influence of cytostatic combination therapy with vincristine sulphate and iphosphamide on blood coagulation].
Disorders of blood coagulation were investigated before and during a cytostatic combination therapy with vincristine sulphate and iphosphamide (Asta Z 4942) in 12 patients with malignant tumours or haemoblastoses. Thromboplastin time, partial thromboplastin time, thrombin time, heat-dependent fibrin, clot retraction, and clotting factors II, V, VIII, IX, X, and the platelet count were determined. A change in the plasmatic coagulation system attributable to the combination therapy could not be demonstrated in any patient. The influence of the cytostatic combination on the platelet-dependent haemostasis was small; a decrease in platelet count could be observed in only one patient, in whom an additional causative damage to thrombopoiesis due to the underlying disease could be assumed. Regardless of the cytostatic therapy there were indications of a hypercoagulability in 10 patients. This explains the increased susceptibility of such patients for thromboses or consumption coagulopathy.
Adult↗