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PubMed1982

On the interaction of heparin-containing polymers with plasma proteins and blood.

In vitro exper iments showed that polymeric hydrogels containing covalently immobilized heparin affect the parameters of blood clotting system. This is not accounted for by the elution of heparin into the surrounding medium and this property of heparin-containing polymers is caused by specific interaction of immobilized heparin with plasma proteins. By the methods of coagulograms and thromboelastography it was revealed that the decrease of total blood anticoagulant activity takes place due to the decrease in blood of fibrinogen, prothrombin and thrombin content and the suppression of fibrin stabilizing factor activity. Free heparin content in blood was left unaffected. It was found that plasma proteins permeate the hydrophilic polymer matrix and interact with immobilized heparin. Binding strength for immobilized heparin is decreased in the array fibrinogen congruent to thrombin much greater than plasmin greater than serum albumin. Complexes of immobilized heparin with fibrinogen, thrombin and plasmin display lytic action towards unstabilized fibrin.

Animals↗
PubMed1994

Assessment of hypercoagulability in patients with cancer using the Sonoclot Analyzer and thromboelastography.

Patients with cancer have an increased incidence of thrombosis and abnormal haemostasis detectable by sophisticated laboratory tests. Whether abnormalities in such highly sensitive assays is clinically relevant to bleeding or thrombosis is not clear. The thromboelastograph (TEG) and Sonoclot analyzers assess the coagulation process in whole blood and may therefore be physiologically more relevant than assays of isolated haemostatic components. Blood was collected from healthy volunteers and patients with breast cancer, colorectal cancer or benign disease and tested in the TEG and Sonoclot. Results in the cancer group were compared to appropriately sex-matched controls. The TEG parameters R (P < 0.02), angle (P < 0.05) and MA (P < 0.001) were abnormal in colorectal cancer; up to 8/17 (47%) patients being assessed as hypercoagulable. R (P < 0.05), angle (P = 0.05) and MA (P < 0.001) were abnormal in breast cancer; 2/21 (9%) patients having abnormal results. In the Sonoclot Analyzer, 11/17 (64%) patients with colorectal cancer had a significant increase in clot rate (P < 0.001) while 2/17 had a decreased SonACT time (P = 0.05). 4/21 (19%) breast cancer patients had a significant increase in clot rate (P < 0.001) and the SonACT was shortened (P = 0.05). Platelets and fibrinogen levels were generally normal and only one patient had clinical evidence of thrombosis. There were no significant coagulation changes in patients with benign colon or breast disease. In conclusion, hypercoagulability was detected in a high proportion of breast and colorectal cancer patients by both techniques. The clot rates of the TEG and Sonoclot were significantly correlated but the latter was abnormal in a greater proportion of cancer patients.

Adult↗
PubMed1984

Purification and properties of the main coagulant and anticoagulant principles of Vipera russellii snake venom.

Vipera russellii venom was separated into thirteen fractions by means of DEAE-Sephadex A-50 column chromatography. Fraction III possessed anticoagulant and phospholipase A activities and Fraction XI possessed procoagulant and caseinolytic activities, both were further purified by gel filtration on Sephacryl S-200 column. Purified procoagulant (Component II) was a two-chain protein with molecular weight of 86 000 consisting of A-chain (Mr 66 000) and B-chain (Mr 20 000). It was a glycoprotein containing 7.8% neutral sugar and 715 amino-acid residues. The procoagulant activity was 10-times that of the crude venom. It was an acidic proteinase with isoelectric point of pH 4.2. Upon heat treatment at 60 degrees C, Component II was stable at pH 5.5 and 7.2 for 3 h, but was destroyed completely after 30 min at pH 8.9. It was devoid of esterase or amidase activity. Purified anticoagulant (Component I) was a single peptide chain with molecular weight of 16 000. It was carbohydrate free and contained 136 amino-acid residues. It was a basic protein with an isoelectric point of larger than pH 10. It was a potent phospholipase A with an enzymatic activity of 510 +/- 30 mumol/min per mg using phosphatidylcholine as substrate, and 1 microgram/ml was sufficient to cause 100% hemolysis by the indirect hemolytic method. Upon heat treatment at 90 degrees C, Component I was heat stable at pH 5.5 for more than 3 h, but was destroyed completely after 2 h at pH 7.2 and 8.9. The anticoagulant activity of Component I could be neutralized by platelet factor 3, tissue thromboplastin and cephalin.

Amino Acids↗
PubMed1987

Characterization of a potent platelet aggregation inhibitor from Agkistrodon rhodostoma snake venom.

By means of CM-Sephadex C-50 column chromatography and gel filtration on Sephadex G-75 and G-50 columns, a potent platelet aggregation inhibitor was purified and characterized. It was a glycoprotein with a molecular weight of 31,000. It was devoid of phospholipase A, ADPase, esterase and fibrino(geno)lytic activities. It inhibited dose-dependently the aggregation of washed platelets induced by collagen, thrombin, sodium arachidonate, platelet activating factor and ionophore A23187 with a similar IC50 (5-10 micrograms/ml). It was also active in platelet-rich plasma, with an IC50 of 10-15 micrograms/ml. The venom inhibitor reduced the elasticity of whole blood clot and inhibited the thrombin-induced clot retraction of platelet-rich plasma. These activities were related to its inhibitory activity on platelet aggregation rather than blood coagulation. The venom inhibitor had various effects on [14C]serotonin release stimulated by aggregation agonists. It had no effect on thromboxane B2 formation of platelets stimulated by sodium arachidonate, collagen and ionophore A23187. The presence of this venom inhibitor prior to the initiation of aggregation was a prerequisite for the maintenance of its maximal activity. It showed a similar inhibitory effect on collagen or thrombin-induced aggregation even when it was added after the platelets had undergone the shape change. High fibrinogen levels partially antagonized its activity. The venom inhibitor completely inhibited the fibrinogen-induced aggregation of alpha-chymotrypsin-treated platelets. It is concluded that this venom inhibitor interferes with the interaction of fibrinogen with fibrinogen receptors, leading to inhibition of aggregation.

Animals↗
PubMed1992

Effects of chromium during pH change on blood coagulation in Tilapia sparrmanii (Cichlidae).

1. Tilapia sparrmanii was exposed to 0.098 mg/l potassium dichromate. 2. The effect of chromium on blood coagulation was measured with a thrombelastograph at a pH of 5, 7.4 and 9 over 96 hr, as well as an uncontrolled pH after 2 weeks of exposure. 3. The prolonged kinetic times and reduced maximal amplitudes at a pH of 7, 4 and 9, differed significantly from the control values. 4. Thrombelastograms reflected a decrease in the clotting ability of fish blood, with an increase in pH, which is typical of thrombocytopenia. 5. It was evident that the exposure of fish to chromium led to clotting defects that caused internal bleeding.

Animals↗
PubMedDate not supplied

A comparison of thromboelastogram and template bleeding time in the evaluation of platelet function after aspirin ingestion.

STUDY OBJECTIVE: To compare template bleeding time (TBT) with thromboelastography (TEG) in human subjects after aspirin ingestion. DESIGN: Healthy volunteers were given a single 650 mg dose of aspirin or a dose of 650 mg of aspirin on three successive days. TBT and TEG studies were performed prior to aspirin ingestion and 4, 24, 72, and 168 hours after ingestion. SETTING: Inpatient operating room support area at the UCLA Center for Health Sciences. VOLUNTEERS: Residents and nurses who were in good general health, had not taken aspirin for 2 weeks, had normal platelet counts, and had no evidence of bleeding or coagulation disorders. INTERVENTION: TBT and TEG studies were performed prior to and after the ingestion of aspirin. MEASUREMENTS AND MAIN RESULTS: TBT studies were significantly prolonged at 4, 24, and 72 hours compared with controls. Maximum bleeding time prolongation occurred 24 hours after aspirin ingestion. Bleeding time returned to control values by the end of 168 hours (1 week). No TEG parameter was significantly changed by aspirin ingestion. CONCLUSION: TEG results may not identify patients who have an increased bleeding time as a result of aspirin ingestion.

Adult↗
PubMedDate not supplied

Influence of ketorolac tromethamine on clot elastic strength in humans as assessed by thromboelastography.

STUDY OBJECTIVE: To evaluate the effect of ketorolac tromethamine on coagulation using thromboelastography (TEG). DESIGN: TEGs were performed in each patient before and after ketorolac administration. Each patient's predrug results were used as control measurements for comparison with the postdrug results. SETTING: Medical center surgical unit. PATIENTS: Twenty ASA physical status I and II patients undergoing minor elective surgery; 12 healthy volunteers. INTERVENTIONS: TEGs were performed in all subjects before and 60 minutes after the intramuscular (IM) administration of ketorolac tromethamine 60 mg. Ten surgical patients were studied in the intraoperative period, and 10 surgical patients were studied in the postoperative period. The 12 healthy volunteers did not undergo a surgical procedure. MEASUREMENTS AND MAIN RESULTS: Specific parameters assessed from the TEGs were reaction time (R time), coagulation time (RK time), clot formation rate (angle of deflection), and maximum clot strength (maximum amplitude of deflection). Ketorolac administration did not cause statistically significant changes in these parameters in any of the three groups studied. CONCLUSIONS: IM administration of ketorolac tromethamine 60 mg did not significantly alter the speed of formation or viscoelastic strength of clots as measured by TEG. These results provide additional support for prior clinical studies confirming the safety of ketorolac administration in the perioperative period.

Adult↗
PubMedDate not supplied

Thromboelastography and Sonoclot analysis in the healthy parturient.

STUDY OBJECTIVE: To compare values for two whole blood viscoelastic coagulation tests, thromboelastography (TEG) and Sonoclot analysis (Sonoclot R Coagulation Analyzer, Sienco, Inc., Morrison, CO), between healthy parturients and nonparturients. DESIGN: Prospective study. SETTING: University hospital. PATIENTS: 41 healthy, nonpregnant females and full-term nonlaboring and laboring parturients. INTERVENTIONS: Blood samples for TEG and Sonoclot analysis were taken from all patients. TEG tracings were analyzed for reaction time (R), coagulation time (RK), the difference between RK and R (K), clot formation rate (alpha degree), and maximum amplitude (MA) values. Sonoclot tracings were analyzed for onset, rate increases, peak, and rate decreases values. MEASUREMENTS AND MAIN RESULTS: All TEG values were significantly different between nonpregnant females and parturients (p < 0.05). Sonoclot analysis showed that the parturients had a significantly decreased onset and increased primary slope (rate increases) in comparison to the nonpregnant females (p < 0.05). CONCLUSION: The differences found in the parturients reflect a hypercoagulable state. If these tests are to be used in evaluating obstetric patients, the results should be compared with values obtained for healthy parturients, not healthy nonparturients.

Blood Coagulation Tests↗