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At least 307 records · Page 17Linked to original sources
PubMed2004

Hemocompatibility of polyacrylonitrile dialysis membrane immobilized with chitosan and heparin conjugate.

Chitosan (CS)/heparin (HEP) polyelectrolyte complex (PEC) was covalently immobilized onto the surface of polyacrylonitrile (PAN) membrane. The effect of surface modification on the protein adsorption and platelet adhesion, metabolites permeation and anticoagulation activity of the resulting membrane was investigated. Surface characterization such as water contact angle, and X-ray photoelectron spectroscope were performed. The immobilization of PEC caused the water contact angle to reduce, thereby indicating the increase in the hydrophilicity. Protein adsorption, platelet adhesion, and thrombus formation were all reduced by the immobilization of HEP. Anticoagulant activity was evaluated with activated partial thrombin time (APTT), prothrombin time (PT), fibrinogen time, and thrombin time (TT). The results revealed that PEC-immobilizing membrane can improve antithrombogenicity of PAN membrane. In addition, the PEC-immobilized membranes can suppress the proliferation of Pseudomonas aeruginosa. In vitro cytotoxicity test showed leachable substance released was below cytotoxic level. The pure water permeability results show little variation due to PEC-immobilization. Thus PEC-immobilization can endow the PAN membrane hemocompatibility and antibacterial activity while retaining the original permeability.

Adsorption↗
PubMed1982

Heparin kinetics determined by three assay methods.

Heparin kinetics were determined in four normal subjects, each of whom received three different doses (25, 50, and 75 units/kg body weight) by intravenous injection. Multiple blood samples were collected after each dose and each plasma sample was assayed for heparin activity using three different assay methods. Two of these assays are based on coagulation tests, i.e., activated partial thromboplastin time and thrombin time, while the third is based on chemical neutralization of heparin using hexadimethrine bromide. Heparin kinetics showed pronounced dose-dependent changes, irrespective of the assay method used, which were characterized by increasing biologic half-life and decreasing total clearance (Cl) with increasing dose. No changes were noted in apparent volume of distribution (Vd). This data also showed that there were differences in kinetic parameters of heparin depending on the assay method. In general, values for total Cl and apparent Vd based on chemical neutralization were approximately 1.5 to 2.0 times these parameters based on coagulation tests. We conclude that the immediate mechanism of the dose-dependent heparin kinetics is decreasing total clearance with increasing dose and suggest that in vivo activation of the anticoagulant properties of heparin may explain the assay-dependent kinetics.

Adult↗
PubMed2003

Changes in coagulation and markers of fibrinolysis in horses undergoing colic surgery.

Activation of coagulation can be frequently found in horses with colic. However, it has also been demonstrated as a sequela of surgical trauma alone in humans. The purpose of the present study was to determine changes in coagulation and fibrinolysis in horses that underwent colic surgery and to evaluate whether these changes were secondary to the colic or the surgery and wound healing. Thirty horses that underwent colic surgery with uncomplicated recovery were included. Ten horses with a Forssell's procedure served as control group with a standardized surgical trauma. Besides daily physical examinations during the observation period of 10 days, activated partial thromboplastin time (aPTT), prothrombin time and thrombin time as well as fibrin monomer (FM), D-Dimer (DD) and antithrombin (AT) III were determined. Compared with the control group the aPTT was the only standard coagulation test that was significantly prolonged before and after the event of colic surgery. After surgery, hyperfibrinogenaemia occurred in all groups. In colic groups FM and DD concentrations were within reference range at admission,and were significantly greater than in control horses after surgery. AT III activity decreased after colic surgery, but did not change in the control group. It was concluded that an activated coagulation state after colic surgery has to be expected, resulting not only from the colic disease, but also from the event of surgery.

Animals↗
PubMed1982

Relation of simple clotting tests to clotting factor levels in liver disease.

The prothrombin time with Manchester and ox thromboplastins, the 'P & P' test of Owren and Aas, the partial thromboplastin time, the thrombin time and assays for factors II, V, VII, VIII:C, IX and X were performed by one observer in 18 patients with liver disease and 27 normal subjects; the prothrombin time and partial thromboplastin time were also carried out on another 28 similar patients by various observers. Routine liver function tests were measured in all patients. The prothrombin time with Manchester thromboplastin was well correlated with other clotting tests, and performing the other tests did not add to the information. Discriminant function analysis confirmed that clotting tests did not distinguish between different types of liver disease. Correlations between clotting tests and liver function tests reflected liver cell damage but were also influenced by acute phase reactions.

Adolescent↗
PubMed1989

[Effects of low molecular weight heparin (FR-860) on coagulative and fibrinolytic activities].

We studied the effects of FR-860 on coagulative and fibrinolytic activities in human plasma compared to conventional unfractionated heparin (UF-heparin). Both FR-860 and UF-heparin dose-dependently prolonged the recalcification time, activated partial thromboplastin time, prothrombin time, factor Xa (F.Xa) clotting time and thrombin time. These effects of FR-860 were weaker than that of UF-heparin. FR-860 showed equipotent efficacy on the anti-F.Xa activity, and weak antithrombin activity compared to UF-heparin. FR-860 had no effects on the activity of ATIII and fibrinolytic activity. UF-heparin shortened the urokinase-activated euglobulin lysis time and showed antiplasmin activity, but did not influence the activities of ATIII, plasminogen and alpha 2-plasmin inhibitor. UF-heparin decreased the fibrinogen level at higher doses. These efficacies of FR-860 were weaker than that of UF-heparin. These results suggest that FR-860 is more efficient and lower in bleeding risk than UF-heparin in clinical use.

Adult↗
PubMed1986

Coagulation assays and platelet aggregation patterns in human, baboon, and canine blood.

Coagulation assays in citrated plasma and platelet-aggregation patterns in citrated platelet-rich plasma were performed, using human, baboon, and canine blood. Similar fibrinogen concentrations, factor VIII antihemolytic factor (AHF) clotting protein concentrations, and thrombin times were seen in human and baboon plasma, whereas prothrombin times and activated partial thromboplastin times were significantly (P less than 0.017) more prolonged in baboon plasma than in human plasma. Canine plasma had significantly lower prothrombin times, activated partial thromboplastin times and thrombin times, and significantly higher concentrations of fibrinogen and factor VIII (AHF) clotting protein than did human plasma. The baboon factor VIII antigen cross-reacted with an antibody against human factor VIII antigen, whereas the canine factor VIII antigen did not. Human and canine platelets had similar aggregation patterns to adenosine diphosphate (ADP), whereas baboon platelets were less responsive to ADP than were human platelets. The response to collagen-induced aggregation in human and baboon blood was similar at concentrations of 0.190, 0.100, 0.050 and 0.025 mg/ml, whereas the response in human and canine blood was similar at concentrations of 0.190, 0.100, and 0.050 mg/ml. The lag time before aggregation with collagen was 2 to 3 times longer for canine platelets than for human platelets; human and baboon platelets had similar lag times. Baboon platelets were more responsive to arachidonic acid than were human platelets at concentrations of 0.25, 0.12, and 0.06 mg/ml, whereas canine platelets were less responsive than were human platelets at the highest concentration of 0.5 mg/ml. Human platelets were more responsive to epinephrine than were baboon or canine platelets.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Hemostatic parameters in newborn--II. Sequential study during the first four weeks of life.

A sequential study of kaolin cephalin clotting time (KCCT), prothrombin time (PT), thrombin time (TT), plasma fibrinogen and serum FDP was conducted during the first four weeks of life on term and preterm babies. A "physiological dip" of PT and TT was noted inappropriate for gestational age (AGA) babies both term and preterm; in case of KCCT, the dip was significant in term AGA babies only. At the end of four weeks, PT and TT had moderately improved in term babies but showed little improvement in preterm ones; KCCT reached almost an adult value in all babies except in preterm AGA and term LGA (large for gestational age) ones. Plasma fibrinogen showed no "physiological dip" and reached adult level in two to four weeks. Serum FDP levels were appreciably raised in preterm AGA babies only at birth and there too normalised by 72 h.

Age Factors↗
PubMed1985

ChromoTimeSystem--a new generation of coagulation analyses.

A new system of reagents and a dedicated instrument for coagulation and fibrinolysis assays, the ChromoTimeSystem is described. All assays are performed in the Chromotimer, a microprocessor controlled 4 channel photometer which is connected to micro computer. Most of the reagents use chromogenic substrates. PT, APTT, fibrinogen, reptilase time and thrombin time are all performed with 25 microliters of sample and 250 microliters of reagent. Neither predilution nor preincubation steps are necessary improving these photometric assays in respect to practicability and speed compared to coagulometric techniques. The use of photometry in contrast to the varying physical principles of classical coagulation analysis will be a step forward into standardization.

Antithrombin III↗
PubMed1983

Combination estrogen and progestogen replacement therapy does not adversely affect coagulation.

Coagulation and fibrinolysis profiles of naturally menopausal women receiving conjugated estrogens (0.625 or 1.25 mg for 21 of 28 days) and medroxyprogesterone acetate (10 mg for seven of 28 days) for 18 months were compared with those of similar women receiving no hormone therapy. Tests indicative of the dynamics of the coagulation cascade, ongoing intravascular coagulation, and anticoagulation were performed. Hormone therapy had no effect on prothrombin times, activated partial thromboplastin times, or thrombin times. There was no evidence of intravascular coagulation in any of the groups as assessed by platelet counts, fibrinogen antigen and activity, and fibrin degradation products. Antithrombin III antigen and activity, alpha 1-antitrypsin antigen, and alpha 2-macroglobulin antigen, the natural inhibitors of coagulation, were also unaffected by hormone therapy. Plasminogen antigen levels were unaffected, but plasminogen activity was enhanced in the hormone-treated groups, suggesting a stimulatory effect on fibrinolysis. These data indicate that in terms of the coagulation system, healthy women can safely use a combined regimen of conjugated estrogens and medroxyprogesterone acetate.

Androstenedione↗
PubMed1995

Chrono-pharmacological study of once daily curative dose of a low molecular weight heparin (200 IU antiXa/kg of Dalteparin) in ten healthy volunteers.

Low molecular weight heparin (LMWH) is currently prescribed for the treatment of deep vein thrombosis at the dose of 100 IU antiXa/kg twice daily or at a dose of 175 IU antiXa/kg once daily with a similar efficacy. We decided to study the chrono-pharmacology of curative dose of LMWH once daily administrated according to the one previously described with unfractionated heparin (UFH). Ten healthy volunteers participated in an open three-period crossover study according to three 24 h cycles, separated by a wash-out interval lasting 7 days: one control cycle without injection, two cycles with subcutaneous injection of 200 IU antiXa/kg of Dalteparin (Fragmin) at 8 a.m. or at 8 p.m. Parameters of heparin activity were analysed as maximal values and area under the curve. Activated partial thromboplastin time (APTT), thrombin time (TT), prothrombin time (PT) and tissue factor pathway inhibitor (TFPI) were higher after 8 p.m. injection than after 8 a.m. injection (p < 0.05) while no chrono-pharmacological variation of anti factor Xa (AXa) activity was observed. Thus the biological anticoagulant effect of 200 IU antiXa/kg of Dalteparin seems to be higher after an evening injection than after a morning injection. A chrono-therapeutic approach with LMWH, as prescribed once daily, deserves further investigation since our results suggest that a preferential injection time may optimise the clinical efficacy of these LMWH.

Adult↗
PubMed1991

The rate of fibrinopeptide B release modulates the rate of clot formation: a study with an acquired inhibitor to fibrinopeptide B release.

An asymptomatic 50-year-old male with a gamma globulin paraprotein was found to have prolonged prothrombin time, activated partial thromboplastin time, and thrombin time but a normal reptilase time. The prolonged clotting times were not the result of a factor deficiency because they were not corrected by the addition of normal plasma. Instead, this patient had an antibody that delayed thrombin-mediated fibrinopeptide B release thereby producing an apparent dysfibrinogenaemia. His isolated IgG prolonged the thrombin clotting time of both normal plasma and fibrinogen. Precincubation of his IgG with fibrinopeptide B, but not with fibrinopeptide A or thrombin, decreased its ability to prolong the thrombin clotting time. The patient's purified IgG but not control IgG delayed thrombin-mediated fibrinopeptide B release from fibrinogen without affecting the release of fibrinopeptide A. These studies define a novel, clinically silent dysfibrinogenaemia due to an antibody that delays thrombin-mediated fibrinopeptide B release from fibrinogen thereby markedly prolonging the clotting times.

Blood Coagulation Disorders↗
PubMed1995

Quantification of thrombelastographic changes after blood component transfusion in patients with liver disease in the intensive care unit.

Thrombelastography (TEG) can be used to monitor hemostasis and guide transfusion therapy during orthotopic liver transplantation. However, data are limited regarding the type and quantity of blood components necessary for TEG-guided blood component transfusion in coagulopathic critically ill patients with liver disease. We evaluated changes in four thrombelastogram variables (reaction time, thrombin constant time, alpha angle, and maximum amplitude) in whole blood samples after 74 separate blood component transfusions in 60 critically ill patients with a coagulopathy and liver disease. Only platelets significantly improved TEG variables in patients who received a single type of blood component. Each unit of platelets decreased the reaction and thrombin constant time by 0.43 (P < 0.05) and 0.82 (P < 0.005) min, respectively, increased the alpha angle by 1.5 degrees (P < 0.005), and the maximum amplitude by 1.4 mm (P < 0.005). In patients who received multiple blood components, cryoprecipitate decreased the thrombin constant time by 0.56 min/U (P < 0.05), and each unit of platelets decreased the thrombin constant time by 0.39 min (P < 0.005), and increased the alpha angle and maximum amplitude by 0.63 degrees (P < 0.05) and 0.99 mm (P < 0.005), respectively. We conclude that platelet transfusions, alone or in combination with other blood components, are most effective for improving abnormal TEG variables in coagulopathic critically ill patients with liver disease.

Blood Coagulation Disorders↗
PubMed1984

Low-dose streptokinase for selective thrombolysis: systemic effects and complications.

The systemic effects and complications associated with the infusion of low-dose (5,000 U/hr) intravascular streptokinase were reviewed in 159 patients. Eighty-two percent of the patients had a 50% decrease in plasma fibrinogen levels during the first 4 hours of treatment, and 100% of the patients showed the same decline following 12 hours of treatment. The thrombin time was prolonged to at least 1 1/2 times the control thrombin time in 42% of the patients at 4 hours of treatment and in 92% at 24 hours of treatment. The rate or degree of change in fibrinogen levels or prolongation of the thrombin time did not correlate with the incidence of complications. Seventeen patients (10.7%) suffered major complications. Thirteen of the 17 had hemorrhagic complications, three had thrombotic or embolic complications, and one had a false aneurysm. In this series, systemic effects occurred in all patients. It is concluded that, despite precautionary measures, hemorrhagic complications may occur. Steps should be taken to minimize complications, including careful observation of the patient and monitoring of plasma fibrinogen levels until adequate regeneration is complete.

Aneurysm↗
PubMed1990

[Parameters of hemostasis during treatments associating fractionated heparin administered subcutaneously to standard and fractionated heparin administered intravenously in the chronic hemodialysis patient].

The hemorrhagic risk of an association of fractioned heparin (Fraxiparine) injected intravenously at the dose of 7500 AXaICU or of unfractionned heparin (UFH) injected intravenously at the usual dose used for a priming dose for hemodialysis (3750 +/- 1280 IU + 1000 IU after 2 hours of dialysis) to the subcutaneous administration of a thrombo-embolism preventive dose of Fraxiparine (7500 AXaICU) was evaluated on the modifications of the following hemostasis parameters: thrombin time, Activated Partial Thrombin Time (APTT), prothrombin time, anti Xa activity in 13 uremic patients on hemodialysis. The association of intravenous and subcutaneous Fraxiparine prevents efficiently the clotting of the extracorporeal circulation without inducing a detectable antithrombinic activity. In contrast, the association of I.V. UFH to subcutaneous Fraxiparine induces a significant increase of the thrombin time and of the APTT. This latter is exclusively explained by the activity of UFH. It is concluded that subcutaneous Fraxiparine at the thromboembolism preventive dose can be associated as well to I.V. Fraxiparine as to UFH without increasing the antithrombinic activity of the plasma.

Aged↗
PubMed1977

[Diagnostic therapeutic problems of defibrination syndrome in shock, sepsis, and neonatal hypoxia (author's transl)].

The diagnosis of defibrination syndrome in shock, sepsis and neonatal hypoxia is based, in addition to the clinical picture, upon a few parameters of the hemostatic system, which, in part as global tests, provide information about the course of coagulation. The parameters measured are partial thromboplastin time, thromboplastin time, plasma thrombin time, fibrinogen, thrombin-coagulase and reptilase times as well as platelet count. Normal values of these laboratory parameters were established for healthy newborns 1--5 days of age, and for healthy adults. It is suggested that especially partial thromboplastin time, the thrombin-coagulase and reptilase times, the latter influenced by fibrinolysis cleavage products, are representative for the tentative diagnosis of disseminated intravascular coagulation with fibrinolysis syndrome (DICFS). The platelet fall often lags 1--2 days behind the event. Moreover normal values for newborns, are markedly higher than those for older children or adults. In the presence of DICFS, a low-dose heparin therapy is immediately initiated. If completed defibrination is manifest, therapy is supplemented with urokinase and streptokinase, For DICFS with congenital sepsis, an exchange transfusion with heparinized fresh blood is the treatment of choice.

Asphyxia Neonatorum↗
PubMed2004

Comparing direct thrombin inhibitors using aPTT, ecarin clotting times, and thrombin inhibitor management testing.

BACKGROUND: Patients with heparin-induced thrombocytopenia and thrombosis may be acutely anticoagulated with direct thrombin inhibitors (DTIs). The anticoagulation is typically monitored using the activated partial thromboplastin time (aPTT) or ecarin clotting time (ECT). OBJECTIVE: To compare 14 methods for measuring aPTT, as well as ECT and thrombin inhibitor management test (TIM), in samples containing DTIs. METHODS: DTIs were added to pooled normal plasma to achieve low (0.1-1.2 microg/mL) and high (1.5-8.0 microg/mL) drug concentrations. Each low-concentration DTI sample was tested using all aPTT reagents, while each low- and high-concentration DTI was tested using the ECT and TIM. RESULTS: All aPTT reagents had a significant dose-dependent correlation with drug concentration. Only Actin FSL and APTT-S demonstrated equivalent aPTT ratios obtained from any DTI. The TAS-aPTT was the most sensitive aPTT reagent to argatroban, with the aPTT ranging from 52.7 to 121.2 seconds corresponding to 0.1 to 1.2 microg/mL of drug concentration. The TAS-aPTT and Pathromtin were the most sensitive aPTT reagents to bivalirudin, with aPTTs of 87.4 seconds and 101.5 seconds, respectively, at 1.2 microg/mL of drug. Pathromtin was the most sensitive aPTT reagent to lepirudin, with a maximum aPTT of 108.9 seconds at 1.2 microg/mL of drug. There was no statistically significant difference between the TIM and ECT clotting times for each DTI. Lepirudin and bivalirudin ECT and TIM clotting times were equivalent. CONCLUSIONS: There are unique differences between reagent manufacturers in the monitoring of DTIs. Acceptable alternatives to aPTT monitoring of DTI anticoagulation include the ECT and TIM.

Arginine↗
PubMed1995

A study of ambrein treatment for the evaluation of change in plasma biochemical parameters in rats.

Biochemical effects of acute and subacute treatments with ambrein were investigated in rats by measuring the total proteins, cholesterol, triglycerides, GOT, GPT and alkaline phosphatase in the blood plasma. Also, determinations of prothrombin time (PT), partial thrombin time (PTT), thrombin time (TT) and fibrinogen level were performed. Furthermore, changes in plasma electrolyte concentration were studied. Ambrein administered i.p. did not cause any toxic symptoms in the liver as revealed by the histology of the liver tissue both in acute and subacute treatments. Ambrein itself did not significantly affect the plasma protein, cholesterol, GOT and GPT profiles, but lowered alkaline phosphatase at high doses (50 and 250 mg/kg) after subacute treatment. Thus far, no specific pattern of action of ambrein in electrolyte control has been found. However, it increased PT, PTT and TT and decreased fibrinogen levels in both the acute and subacute studies, pointing towards its potential as an anticoagulant and antifibrinogenic agent.

Alanine Transaminase↗