ristocetin and Kidney-Failure--Chronic

Erythropoietin corrects anemia and improves hemostasis, but on the other hand bears a risk of thrombotic complications. Therefore in the present study an attempt has been made to evaluate bleeding time, platelet functions and some hemostatic and fibrinolytic parameters in relation to blood and platelet serotonin before and after 1, 2, 4, 8 and 12 weeks of treatment. 22 chronically hemodialyzed patients were administered with human recombinant erythropoietin (rHuEPO) in a dose of 2000 IU s.c. 3 times a week. Bleeding time was shortened significantly as early as after 1 week of the therapy, whereas hematocrit and hemoglobin increased after 2 weeks. These changes lasted throughout the study. Only a transient rise in platelet count, collagen-induced platelet aggregation, beta-thromboglobulin and VIII:C activity were observed during therapy relative to baseline values. ADP- and arachidonic acid-induced platelet aggregation seemed to be unaffected by rHuEPO treatment, whereas a gradual and progressive enhancement in platelet aggregation in response to ristocetin was found, starting from the 2nd week of the therapy. It lasted throughout the study and correlated inversely with the bleeding time and positively with a rise in both blood and platelet serotonin. rHuEPO did not alter plasminogen, fibrinogen, platelet factor 4, alpha 2 macroglobulin levels, protein C activity and euglobulin clot lysis time. A decline in protein C and S concentrations and antithrombin III activity observed during the therapy were counterbalanced by a fall in the activity of alpha 2 antiplasmin, C1 esterase inhibitor and plasminogen activator inhibitor. It is concluded that rHuEPO may improve platelet/vessel wall interactions possibly by means of serotonergic mechanisms. A lowered activity of inhibitors of fibrinolysis may be regarded as a protection against a general tendency to thrombosis during rHuEPO therapy.

Topics: Adenosine Diphosphate; Adult; Anemia; Arachidonic Acid; Biomarkers; Bleeding Time; Blood Platelets; Blood Proteins; Erythropoietin; Female; Fibrinolysis; Hematocrit; Hemoglobins; Hemostasis; Humans; Kidney Failure, Chronic; Male; Middle Aged; Platelet Aggregation; Recombinant Proteins; Renal Dialysis; Ristocetin; Serotonin; Thromboembolism; Time Factors

Topics: Adenosine Diphosphate; Arachidonic Acid; Collagen; Humans; Immunosuppressive Agents; In Vitro Techniques; Kidney Failure, Chronic; Mycophenolic Acid; Platelet Aggregation; Ristocetin; Uremia

A pathogenetic role for fibrin deposition and platelet activation in the kidney is thought to play a role in the pathogenesis of acute renal failure (ARF). Thus, some fibrinolytic parameters and platelet function have been studied in 17 patients with ARF and compared to healthy volunteers and subjects with chronic renal failure (CRF). Since serotonin may participate in pathological processes resulting from platelet/vessel wall interactions, its level in the whole blood and plasma was also assayed. In ARF and CRF platelet aggregatory responses in both whole blood and in platelet rich plasma upon stimulation with various agonists (collagen, arachidonic acid, ADP, ristocetin) were lower than those obtained in healthy volunteers. Increased levels of lipoprotein (a), von Willebrand factor (vWF) and fibronectin were found in ARF relative to controls. Protein C activity was significantly lower in patients with ARF. Euglobulin clot lysis time was prolonged in ARF and CRF, reflecting a decreased overall fibrinolytic activity. Activity of tissue plasminogen activator (tPA) inhibitor (PAI) and PAI:Ag were higher in ARF, whereas tPA:Ag, urokinase, tPA/PAI complexes, thrombin-antithrombin complexes (TAT), plasmin-antiplasmin (PAP) complexes, fibrinogen, and F1+2 did not differ between ARF and controls. In CRF elevated levels of TAT, PAP, fibrinogen and prothrombin fragments F1+2 were found, whereas concentration of fibronectin was lowered when compared to controls. In both groups of renal failure patients increased levels of fibrin monomers and d-dimer were found relative to healthy volunteers. Whole blood serotonin was significantly lower, whereas plasma serotonin was significantly higher in patients with ARF and CRF relative to controls. Serotonin uptake and its release from platelets were markedly diminished in patients with ARF and CRF. Chronic renal failure exhibit a slightly different pattern of coagulopathies that acute renal failure.

Topics: Acute Kidney Injury; Adenosine Diphosphate; Adolescent; Adult; Aged; alpha-2-Antiplasmin; Antithrombin III; Arachidonic Acid; Blood Platelets; Collagen; Female; Fibrinolysin; Fibrinolysis; Fibronectins; Hemostasis; Humans; Kidney Failure, Chronic; Lipoprotein(a); Male; Middle Aged; Peptide Fragments; Peptide Hydrolases; Plasminogen Activator Inhibitor 1; Platelet Aggregation; Prothrombin; Renal Dialysis; Ristocetin; Serotonin; Tissue Plasminogen Activator; von Willebrand Factor

Topics: Adenosine Diphosphate; Arachidonic Acid; Azathioprine; Collagen; Humans; Immunosuppressive Agents; In Vitro Techniques; Kidney Failure, Chronic; Platelet Aggregation; Reference Values; Renal Dialysis; Ribonucleosides; Ristocetin; Serotonin; Uremia

Topics: Erythropoietin; Humans; Kidney Failure, Chronic; Ristocetin; von Willebrand Factor

There are data suggesting that recombinant human erythropoietin (rHuEPO) may induce thromboses in hemodialysis patients, possibly due to alterations in platelet function. In an earlier study, we found evidence of platelet hyperfunction in several patients 4 to 8 weeks following the start of rHuEPO therapy, which was begun shortly after hemodialysis was initiated. Studies were performed to examine the effects of rHuEPO on whole blood platelet aggregation and adenosine triphosphate (ATP) release independent of changes in hematocrit or the uremic state. Eight hemodialysis patients without and four with a history of vascular access clotting had platelet aggregation tests performed at baseline while receiving rHuEPO, off rHuEPO for 2 weeks, and 4 to 6 weeks after restarting the drug. While the plasma EPO level decreased significantly after the 2-week period off rHuEPO (P < 0.0001), the hematocrit did not change at any of the three time periods. Whole blood platelet aggregation in response to adenosine diphosphate (ADP), collagen, and ristocetin was not significantly altered on or off rHuEPO in either patient group. Platelet hyperfunction, determined by aggregation or ATP release either spontaneously or in response to low-dose ADP or ristocetin, was not seen in any patient. These data suggest that the increase in access clotting is not the result of platelet hyperfunction induced directly by rHuEPO.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Adult; Aged; Aged, 80 and over; Blood Platelet Disorders; Collagen; Erythropoietin; Female; Hematocrit; Humans; Kidney Failure, Chronic; Male; Middle Aged; Platelet Aggregation; Recombinant Proteins; Renal Dialysis; Ristocetin

Patients with uraemia have abnormal platelet function that may be partially corrected by haemodialysis, cryoprecipitate or 1-desamino-8-D-arginine vasopressin (DDAVP). We studied the platelet von Willebrand factor receptor, glycoprotein Ib (GPIb), and plasma von Willebrand factor (vWF) in uraemic patients undergoing chronic haemodialysis. Using the slope of agglutination of formalin-fixed platelets as an index of response to ristocetin (with a constant amount of normal plasma as a source of vWF), we found the response of platelets from uraemic patients, both before (2.7 +/- 1.5, n = 40) and after dialysis (1.2 +/- 1.2, n = 40) to be significantly less than that for normal controls (14.1 +/- 10.2, n = 20; P less than 0.001). In addition, the agglutination response of platelets obtained after dialysis was less than that of platelets obtained before dialysis (P less than 0.001). Immunoblotting demonstrated decreased or absent staining of glycocalicin, a subunit of GPIb, in platelet lysates from 25 patients. All platelet samples with reduced glycocalicin also had decreased responses to ristocetin. Tritium-labelled platelets from seven patients showed decreased labelling of a protein with an electrophoretic mobility equivalent to that of GPIb (140,000 daltons). In addition, platelets with the lowest levels of surface GPIb, as demonstrated by flow cytometry, also had decreased ristocetin agglutination and decreased staining on immunoblot. Levels of von Willebrand factor antigen and ristocetin cofactor in plasma from 10 patients were generally within the normal range, although postdialysis levels tended to be higher than pre-dialysis levels. The pre- and post-dialysis plasma vWF multimeric patterns were normal.

Topics: Adult; Aged; Electrophoresis, Polyacrylamide Gel; Female; Humans; Immunoblotting; Kidney Failure, Chronic; Male; Middle Aged; Platelet Aggregation; Platelet Membrane Glycoproteins; Renal Dialysis; Ristocetin; Uremia; von Willebrand Factor

Several mechanisms have been proposed to explain the prolonged bleeding times and clinical bleeding in chronic renal failure. Recent evidence has implicated an abnormality in the structure or function of the von Willebrand factor or in its interaction with uremic platelets. We investigated this factor in 11 patients with chronic renal failure.. Blood samples for cell counts, chemistries, and coagulation studies were obtained from 11 patients with chronic renal failure and prolonged bleeding times. Concentrations of von Willebrand factor antigen and ristocetin cofactor activity were determined in plasma and platelets. Multimeric analysis of von Willebrand factor in plasma and platelets was conducted. In eight cases, the platelets of uremic patients were purified, and the thrombin- and ristocetin-induced binding of normal von Willebrand factor to these platelets was examined.. The mean plasma von Willebrand factor antigen and activity (ristocetin cofactor assay) were elevated 2.77 mu/ml and 1.88 mu/ml, respectively (normal, 1.01 mu/ml and 1.07 mu/ml, respectively). The ratio of activity to antigen in uremic plasma was 0.67 (normal, 1.05). The mean platelet von Willebrand factor antigen and activity in the uremic patients was decreased (0.26 and 0.50 mu/10(9) platelets, respectively) compared with normal patients (0.46 and 0.93 mu/10(9) platelets, respectively). The oligomeric structure of the uremic plasma von Willebrand factor lacked the largest multimers. Collection of the blood for analysis in several protease inhibitors and/or EDTA did not change the multimeric structure. The von Willebrand factor multimeric structure of platelets from uremic patients was normal. The ristocetin-induced platelet aggregation of the uremic platelet-rich plasma was decreased compared with normal plasma samples. Thrombin and ristocetin-induced binding of normal von Willebrand factor to uremic patients' platelets was indistinguishable from the binding to normal platelets.. These data suggest that the uremic platelet-binding sites for von Willebrand factor are intact and that the defect in ristocetin-induced platelet aggregation is most likely plasmatic in nature. At least one plasmatic defect was the observed reduction or absence of the largest plasma von Willebrand factor multimer in uremic patients. The platelet von Willebrand content was significantly decreased. These defects may play a role in the prolonged bleeding time and the clinical bleeding observed in patients with uremia.

Topics: Bleeding Time; Blood Platelets; Chromatography, Agarose; Humans; Kidney Failure, Chronic; Molecular Weight; Platelet Aggregation; Platelet Count; Protein Binding; Ristocetin; Uremia; von Willebrand Factor

The platelet element content was determined by semiquantitative X-ray microanalysis in 6 patients with chronic renal failure. The patients showed a different degree of thrombocytopathy expressed by impaired adhesiveness, epinephrine-induced aggregation and platelet factor 3 availability. The microanalysis indicated significantly increased quantities of phosphorus and copper in patients' platelets. Sodium and zinc showed a decrease in about half of the patients, whereas iron was significantly increased in at least 50% of the patients. Magnesium and potassium did not show any difference from the control. The results of sulfur, chlorine and calcium did not reveal a consistent pattern.

Topics: Arachidonic Acid; Arachidonic Acids; Blood Platelets; Collagen; Copper; Electron Probe Microanalysis; Elements; Epinephrine; Humans; Iron; Kidney Failure, Chronic; Phosphorus; Platelet Aggregation; Platelet Factor 3; Ristocetin; Sodium; Zinc

Chronic renal failure causes elevations of factor VIII coagulant activity and Factor VIII-related antigen even before the patients enter chronic hemodialysis. The change from control of Factor VIII ristocetin cofactor does not reach significance. The elevations are not effected by entering onto hemodialysis. These parameters are the same for non-diabetic and diabetic patients. Protein C, plasminogen and total fibrinolytic capacity are normal in diabetic and non-diabetic patients, with or without hemodialysis for chronic renal failure. However, before entering onto hemodialysis some of these parameters had negative correlation coefficients with parts of the factor VIII complex among the diabetic and non-diabetic patients. These negative correlates turned positive after hemodialysis. Thus, there are differences in these catabolic mechanisms for factor VIII when hemodialysis is used for diabetic and non-diabetic patients with chronic renal failure.

Topics: Adult; Aged; Carrier Proteins; Diabetic Nephropathies; Factor VIII; Fibrinolysis; Humans; Kidney Failure, Chronic; Middle Aged; Plasminogen; Renal Dialysis; Ristocetin