Effect of heparin on chronically induced intravascular coagulation in dogs.

When intermediate-strength thromboplastin was continuously infused into dogs for 10 days or more, platelet counts decreased sharply and factor VIII concentrations decreased by more than 50%. There was little change in plasma fibrinogen, prothrombin, factor V, antithrombin III, plasminogen, prothrombin time, and thrombin time values. When heparin was infused (25-50 U/kg per h) along with the same thromboplastin, there was no change in onset or degree of thrombocytopenia. However, the decrease in factor VIII was abolished and there were significant increases in fibrinogen, prothrombin, and factor V. The absolute concentrations of the various clotting factors seemed to give no indication of their turnover rates. Unexplained is the remarkable heparin tolerance that developed in these dogs.     

Coagulation parameters of captive mountain gazelle (Gazella gazella Pallas, 1766; Bovidae: Antilopinae) and Nubian ibex (Capra ibex nubiana Cuvier, 1825; Bovidae: Caprinae)

The coagulation profiles of 36 mountain gazelles (Gazella gazella) aged 2–6?years, and 17 Nubian ibexes (Capra ibex nubiana), aged 1–4?years, were evaluated and compared. The following parameters were determined in both species: prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen concentration (FIB), and clotting factors VII, VIII:C, IX, X, and XI. Thrombin clotting time (TCT) was also determined in mountain gazelles. The results indicated significant interspecies differences in most parameters, with lower PT, aPTT, and factors VII, IX, and XI and higher factor XIII:C activities in the Nubian ibex than the mountain gazelle. Gender seemed to have a limited influence on these parameters within each species. Both species had higher plasma FIB and factor VIII:C activity relative to humans. This study is the first record of coagulation variables in these two species of wild Arabian desert ruminants.     

Circadian variation of blood clotting time and circulating vitamin K in the athletic horse

In equine sport medicine, blood clotting and fibrinolysis variations are well investigated, given the practical implications of several pathophysiological conditions affecting the athlete horse such as exercise-induced pulmonary haemorrhage (EIPH) and other bleeding disorders whose etiology and pathogenesis mechanisms are not yet clearly understood. The purpose of the present investigation was to gain evidence of a daily rhythm of several blood clotting indices such as prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), plasma fibrinogen concentration and serum vitamin K concentration in the athletic horses. Blood samples from five thoroughbred mares were collected at 4-h intervals for 48 h (starting at 08:00 h on day 1 and finishing at 4:00 on day 2 via an intravenous catheter inserted into the jugular vein. Prothrombin time, activated partial thromboplastin time, thrombin time and plasma fibrinogen concentration were assessed by means of a Seac Clot 2 coagulometer (SEAC, Italy), while serum vitamin K concentration was measured by HPLC. Data analysis was conducted by one-way repeated analysis of variance (ANOVA) and by the single cosinor method. ANOVA showed a significant influence of time on all parameters investigated, in all horses, on either day. Cosinor analysis defined the periodic parameters and their acrophases (expressed in hours) during the 2 days of monitoring. PT showed a nocturnal acrophase, whereas serum vitamin K concentration acrophase occurred during the evening. The results of this study reflect the physiological peculiarities of the horse that is subjected to a number of exogenous (environmental, nutritional, physical) and endogenous stimuli capable of entraining the circadian rhythm specifically and thus producing time-dependent variations not always comparable with those observed in humans or laboratory animals.     

Evaluation of four coagulation tests to detect plasma lupus anticoagulants.

Lupus anticoagulant was detected in 205 newly diagnosed, untreated patients with systemic lupus erythematosus by the following tests: kaolin clotting time, activated partial thromboplastin time, plasma prothrombin time, and, in the last 99 patients, by dilute Russell's viper venom time. In 10 patients, lupus anticoagulant was detected by kaolin clotting time prolongation, corrected by inosithin but not by normal plasma; 12 and 6 of them had prolonged activated partial thromboplastin time and partial plasma prothrombin time, respectively. Only 10 patients had a history of recurrent abortions and/or thrombosis, nine of whom had lupus anticoagulant as shown by the kaolin clotting time test. Of the 99 patients studied by all four tests, 9 showed lupus anticoagulant by both kaolin clotting time and dilute Russell's viper venom time; 7 had a history of abortion and/or thrombosis. The dilute Russell's viper venom time test is easy to perform and not affected by inhibitors to factor VIII or IX. It is recommended as a primary screening test for lupus anticoagulant detection in a hospital clinical laboratory.     

Lack of fibrin formation in exercise-induced activation of coagulation.

Strenuous physical exercise leads to a significant shortening of blood clotting in various test systems. Such short times are also characteristic of those observed in sedentary patients with thrombosis or disseminated intravascular coagulation, and of those observed in experimental animals after thrombin infusion. The patients exhibit an increase in circulating fibrinopeptide A, which is attributed to thrombin action on circulating fibrinogen, and to an increase of fibrinogen degradation products, which is thought to indicate reactive fibrinolysis. To check whether physical exercise leads to fibrinemia, 10 healthy male volunteers were subjected to strenuous exercise on a bicycle ergometer. Blood samples were taken immediately before and on completion of the exercise period. Despite a significant shortening of the activated partial thromboplastin time, the thrombin time, and the Reptilase time, no increase of fibrinopeptide A could be demonstrated and the ethanol gelation test remained consistently negative. Simultaneously, the euglobulin lysis time was significantly shortened, whereas the fibrin(ogen) degradation products did not increase. The results indicate that the shortening of the coagulation times associated with physical exercise must be explained by mechanisms other than thrombin-mediated conversion of fibrinogen to fibrin.     

Variation of the fibrinogen concentration in the blood after intravenous injection of thrombin in animals that received dicoumarin

Summary Albino rats ranging in weight from 180 to 200 g were given dicoumarin per os. The first group of animals were given a single 5 mg dose of the preparation shortly before the experiment. To rats of the second group dicoumarin was administered during three days: a 5 mg dose on the first day, and a 2 mg dose on the second and third day before the experiment. On the day of the experiment the rats were given thrombin intravenously; the fibrinogen content of the blood was examined before and six minutes after the injection, as well as changes in the following tests were studied: total time of coagulation, prothrombin time, thrombin time, and the time of thromboplastin generation. It was found that within the first 24 h of administration of a single dicoumarin dose the intravenous injection of thrombin caused in the test animals a larger decline of fibrinogen concentration than in the control animals. The animals given dicoumarin during three days reacted to intravenous thrombin injection in the same way as the control rats.(Presented by Member of the Academy of Medical Sciences USSR, S. E. Severin) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 61, No. 1, pp. 46–48, January, 1966     

Horn fly (Diptera: Muscidae) saliva targets thrombin action in hemostasis

The horn fly, Hematobia irritans (L.), is an important pest of livestock because the adult stage of both sexes are aggressive blood-feeders. Remarkably, even though horn fly adults feed recurrently on their hosts as ectoparasites, these flies lack the ADP-responsive antiplatelet aggregation and vasodilatory antihemostatic systems described for other blood-feeding Diptera. Horn fly salivary gland extracts do interfere with the normal coagulation process as demonstrated by the recalcification time assay. Using this as a baseline, the effects of saliva on recalcification time, activated partial thromboplastin time, prothrombin time, and thrombin time were measured to determine which arm(s) of the coagulation cascade might be impacted. Factor-deficient plasma assays also were used to measure possible perturbations in clotting. Gland-free saliva delayed the recalcification time as well as the activated partial thromboplastin time, prothrombin time, and thrombin time. Saliva also further delayed clotting times of plasmas deficient in factor V, factor VIII, and factor XIII, indicating that other factors in the coagulation cascade were inhibited. Although horn fly saliva did not alter the ability of deficient plasma reconstituted with factor X to clot, it did inhibit deficient plasma reconstituted with factor II (thrombin). Antithrombin activity in saliva was confirmed by its ability to interfere with thrombin hydrolysis of fibrinogen, its normal substrate, and by its inhibition of thrombin action on a chromagenic substrate that mimics the hydrolytic site of fibrinogen. Thus, horn fly saliva contains a factor that specifically targets thrombin, a key component in the coagulation cascade. While the biochemical mechanisms of inhibition may vary, this antihemostatic characteristic is shared with other zoophilic Diptera such as black flies, Simulium spp., and tsetse, Glossina morsitans morsitans Westwood, that feed on ungulates.     

膝关节置换中应用骨水泥和止血带对凝血功能的影响

背景：有研究表明膝关节置换中骨水泥固定假体时骨水泥对患者的血液动力学及凝血功能的影响较大。 目的：观察膝关节置换中骨水泥和止血带对患者凝血功能的影响。 方法：采用随机对照研究方法,将骨性关节行单侧膝关节置换患者40例随机分成2组,置换时分别应用止血带和不用止血带。通过比较两组患者血浆凝血酶原时间、活化的部分凝血活酶时间、凝血酶时间、纤维蛋白原及血浆D-二聚体水平的变化,来观察膝关节置换中骨水泥和止血带对置换中凝血功能的影响。 结果与结论：两组患者在骨水泥置入后60,120 min,血浆凝血酶原时间值缩短(P < 0.05),纤维蛋白原和D-二聚体在注入骨水泥后增多(P < 0.05),其中止血带组的变化更为明显,两组患者在180 min时基本恢复正常,活化的部分凝血活酶时间及凝血酶时间在骨水泥注入前后均无明显变化,另外,所监测的凝血功能相关指标(血浆凝血酶原时间、活化部分凝血酶原时间、凝血酶时间、纤维蛋白原及D-二聚体的数值在注入骨水泥前后均在正常范围内。相比非止血带组,止血带组血浆凝血酶原时间缩短、纤维蛋白原及D-二聚体含量增多(P < 0.05)。说明膝关节置换中骨水泥应用后可以使单侧膝关节置换患者的凝血功能处于高凝状态,止血带可加重患者的高凝状态。     

Coagulation and fibrinolytic changes in evolving acute myocardial infarction treated by high-dose, brief-duration intracoronary or intravenous streptokinase

Twenty-two patients were infused with 240,000 units streptokinase during a 60-minute period into the ostium of the infarct-related coronary artery (IC), and 23 patients were infused with 1,500,000 units streptokinase intravenously (IV) over 45 minutes; all infusions occurred within 12 hours of the patients' onset of chest pain. Thereafter, heparin was infused for 10 days. Serial coagulation and fibrinolytic parameters were studied over 46 to 72 hours after the streptokinase infusion. A generalized fibrinolytic state was produced in both groups as evidenced by a fall in fibrinogen and plasminogen levels, prolongation of thrombin and reptilase clotting times, a rise in fibrinogen degradation products, and a shortening of the euglobulin lysis time. Recovery to preinfusion levels was similar in both groups of patients. Hemorrhagic complications requiring blood replacement occurred in 7/23 (30%) treated IC, and 4/23 (17%) in the IV group.     

Hemostatic abnormalities in malignancy, a prospective study of one hundred eight patients. Part I. Coagulation studies.

A prospective study of hemostatic abnormalities in 108 cancer patients was undertken at an oncology clinic in a university teaching hospital. Tests included Quick prothrombin time, activated partial thromboplastin time, thrombin time, platelet count, modified Ivy bleeding time, fibrinogen, fibrin degradation products (FDP), euglobulin lysis time, protamine sulfate test, and factor V, VII, VIII and X assays. Ninety-eight per cent of the patients had one or more abnormal coagulation tests. The commonest abnormalities were elevated fibrin degradation products and prolonged thrombin time. Thrombocytosis occurred in 57% of patients, hyperfibrinogenemia in 46%, thrombocytopenia in 11%, and non had hypofibrinogenmia. It is suggested that platelet count, fibrinogen concentration, and serum FDP assay are the most useful tests in assessing the hemostatic abnormalities in cancer patients, although thrombin time, factor V assay, and bleeding time may also be helpful. The peripheral blood smears of 53 patients were reviewed, and only one showed microangiopathic hemolytic anemia. The data illustrate that subclinical coagulopathy is relatively frequent in patients with malignancy.     

Blood coagulation indices in rabbits vaccinated with BCG

Summary Determination was made of the blood coagulation time, recalcification time, prothrombin time and fibrinogen content in the plasma of 8 BCG-vaccinated rabbits and 6 control animals. On the 3rd-15th days after vaccination changes occurred in the blood coagulation indices of the immunized animals. During the initial immunization period (up to 6th observation day) there was a reduction of the blood coagulation time and prothrombin time, whereas the initially increased fibrinogen content began to drop, without however reaching the control figures. Consequently, there is a tendency for a rise in the total blood coagulation capacity at the initial period of immunity production. On the 90–120th experimental days the blood coagulation capacity proved to be reduced as indicated by a decreased fibrinogen content and a rise in prothrombin time.(Presented by Active Member AMN SSSR V. N. Chernigovskii) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 57, No. 2, pp. 88–89, February, 1964     

Platelet reactions in acute Plasmodium berghei infection in Swiss albino mice

Swiss albino mice were infected by the intraperitoneal route with P. berghei berghei malaria parasite, and platelets, white cell counts and some coagulation parameters were monitored in order to find out whether changes reported in man also occurred in the mice. Parasitaemia developed form the 2nd post-infection day and reached significant levels by the 4th-6th day. Reduced circulating platelets which reached severe thrombocytopenic levels were observed. parallel with the increasing degree of parasitaemia. Anaemia which progressed to severe degree was also observed as was a slight leucocytosis attributed to the presence of normal mouse erythrocytes in the peritoneal space. All untreated animals died by the 6th day of infection. Intramuscular chloroquine sulphate (20 micrograms/g body wt.) given for 7 days completely cured the malaria, and white cell and platelet counts were restored to preinfection levels in each animal about 2 weeks after treatment had ceased. Platelet hypersensitivity to exogenous ADP was observed within 48 hours of infection and persisted with the parasitaemia. Prothrombin time (PT) and activated partial thromboplastin time (APTT) were prolonged while clottable fibrinogen concentration was reduced.     

Anti-c5a ameliorates coagulation/fibrinolytic protein changes in a rat model of sepsis

Sepsis and trauma are the two most common causes of disseminated intravascular coagulation and multiple organ dysfunction syndrome. Both disseminated intravascular coagulation and the systemic inflammatory response syndrome often lead to multiple organ dysfunction syndrome. The current studies have evaluated the relationship between the anaphylatoxin, C5a, and changes in the coagulation/fibrinolytic systems during the cecal ligation and puncture (CLP) model of sepsis in rats. CLP animals treated with anti-C5a had a much improved number of survivors (63%) compared to rats treated with pre-immune IgG (31%). In CLP rats treated with pre-immune IgG there was clearly increased procoagulant activity with prolongation of the activated partial thromboplastin time and prothrombin time, reduced platelet counts, and increased levels of plasma fibrinogen. Evidence for thrombin formation was indicated by early consumption of factor VII:C, subsequent consumption of factors XI:C and IX:C and anti-thrombin and increased levels of the thrombin-anti-thrombin complex and D-dimer. Limited activation of fibrinolysis was indicated by reduced plasma levels of plasminogen and increased levels of tissue plasminogen activator and plasminogen activator inhibitor. Most of these parameters were reversed in CLP rats that had been treated with anti-C5a. Production of C5a during sepsis may directly or indirectly cause hemostatic defects that can be reduced by blockade of C5a.     

Comparison of an immunochemical assay for plasma fibrinogen and a turbidimetric thrombin clotting technique to discriminate hyperlipidaemic patients from healthy controls.

Plasma samples from patients attending a lipid clinic (n = 14) and healthy control subjects (n = 21) were assayed for fibrinogen using an immunochemical method (radial immunodiffusion) and a turbidimetric assay based on the thrombin clotting technique. The patients had significantly higher plasma fibrinogen concentrations than controls by both methods, but there was significant overlap between the two groups when fibrinogen was assayed by the thrombin clotting technique; there was almost complete separation of the two groups using the immunochemical assay. This difference in overlap could not be attributed to the presence or absence of fibrinogen degradation products. These findings may have important implications for the choice of method for determining plasma fibrinogen when assays are used for the assessment of cardiovascular risk. It is recommended that plasma fibrinogen should be assayed by both an immuno-chemical and a thrombin clotting method.     

Studies on phospholipids in the action of a lupus coagulation inhibitor.

Plasma from a patient with early manifestations of disseminated lupus erythematosus, a prolonged partial thromboplastin time with kaolin, mildly prolonged prothrombin time, and a circulating inhibitor affecting the assay of several clotting factors was investigated. The most sensitive test for the inhibitor was found to be the Russell viper venom time without phospholipid. A decrease in phospholipid concentration as well as decreased sodium chloride levels both significantly enhanced the effect of the inhibitor in several coagulation tests. Of various phospholipid substitutes tested phosphatidyl ethanolamine was the most effective in partially correcting for the inhibitor. The inhibitor was not localized to the patient's platelets, which were also found to partially neutralize its effect. Since lupus erythematosus is sometimes accompanied by thrombocytopenia the coagulation disorder may be aggravated by such a deficiency of phospholipid. The inhibitor appears to act by preventing binding of phospholipid to the Xa/V/thromboplastin complex. It was characterized as a gamma globulin of mixed class.     

Alteration of blood coagulation and complement system in neotropical primates infected with Junin virus

The neotropical primate Callithrix jacchus infected with Junin virus presented an acute disease with hematological and neurological manifestations and died 17 to 24 days after infection. This picture is similar to that of human Argentine hemorrhagic fever (AHF). Blood coagulation and complement studies were performed in ten C jacchus animals inoculated with 10³ TCID₅₀ of Junin virus, the prototype pathogenic XJ strain. Four monkeys were used as normal controls. Infected monkeys and normal controls were bled to death on days 7, 14, 17, and 21. A progressive decrease in the number of platelets was found after day 7 of infection. On day 21, the last monkey had a value of 24,000/μl. The levels of blood clotting factors did not change until day 17, when a shortened partial thromboplastin time activated with Kaolin (PTTK) (36 sec) and increased factors VIII (192.2%) and VII-X (266.6%) were found. On day 21, the PTTK was prolonged (50.7 sec) and factors II, V, and VIII, were decreased. Thrombin time was found prolonged from day 14 onward. Fibrinogen and fibrin degradation products (FDPs) were increased on days 17 (754 mg/dl and 9.2 μg/ml) and 21 (457 mg/dl and 29.4 μg/ml). No changes in the levels of α₂ macroglobulin were observed. Complement hemolytic levels were found to be low on day 7 (58.3 UCH₅₀, increased on day 14 (165.1), and within normal range at the end of infection (107.2). C3 levels showed a similar pattern. The bone marrow was active and hypercellular, and the number and morphology of megakaryocytes were normal in all but one of infected animals. The results of blood clotting suggest a limited activation. The complement system presented a profile of activation followed by a rebound phenomenon. The activation of complement appeared ten days before the alteration of the clotting system was evident.     

Modified plasma-based ecarin clotting time assay for monitoring of recombinant hirudin during cardiac surgery

Recombinant hirudin (r-hirudin) is being used increasingly for therapeutic anticoagulation in patients with heparin-induced thrombocytopenia undergoing cardiovascular surgery. Although multiple laboratory methods are available for measuring r-hirudin, the ecarin clotting time (ECT) is the most commonly used for this purpose. Ecarin (extracted from snake venom) converts prothrombin to meizothrombin, which promotes clot formation. Direct thrombin inhibitors, like r-hirudin, bind meizothrombin and yield a linear, dose-dependent prolongation of ECT. Low levels of prothrombin and fibrinogen in plasma samples can lead to higher ECT; suggesting falsely elevated r-hirudin levels. A modified ECT assay with prothrombin and fibrinogen in excess was optimized using an orthogonal array method to eliminate the variations in patients' plasma prothrombin and/or fibrinogen levels for accurate determinations of plasma r-hirudin levels. By using the modified ECT assay, falsely elevated r-hirudin levels can be avoided in patients undergoing cardiopulmonary bypass, thus providing reliable and accurate r-hirudin monitoring in this clinical setting.     

Plasma fibrinogen concentration is increased following depletion of vitamin K-dependent clotting factors by the indirect anticoagulant difenacoum in norway rats (Rattus norvegicus)

Difenacoum, a 4-hydroxycoumarin anticoagulant rodenticide with the same mode of action as warfarin, was fed to four strains of rat in medium oatmeal at 0.005% (w/w) for five days. The four rat strains had differing degrees of resistance to the anticoagulant difenacoum. Prothrombin time, factor X and fibrinogen concentration were monitored daily throughout the feeding period, and for a further 8 days following feeding. After 24 h factor X had been reduced in susceptible rats to 25% and fibrinogen had increased to 110% of resting levels. By 48 h prothrombin times were so extended that it was impossible to estimate the levels of fibrinogen in rats of this susceptible strain beyond that time point. As factor X levels reduced, fibrinogen levels increased in the plasma of rats with medium resistance levels. Feeding of difenacoum to highly resistant rats caused little, if any, extension of prothrombin time and enabled further comparison of fibrinogen and factor X levels in these animals. Fibrinogen levels did not increase significantly in the highly anticoagulant-resistant rats which had normal concentrations of factor X levels throughout the experiment. It is, therefore, unlikely that increased levels of fibrinogen resulted from direct effects of difenacoum. Changes in fibrinogen levels may be caused by a feedback mechanism in response to changes in the plasma concentration of factor X and/or other vitamin K-dependent clotting factors. These changes appeared to partially reduce the effect of factor X loss on the prothrombin time and may be a secondary mechanism of resistance of potential importance in the survivorship of rats on farms during a control treatment.     

The effect of change in the rhythm of food intake and sleeping time during ramadan on the diurnal variation of fibrinolytic activity

Consecutive measurements of blood coagulation and fibrinolytic parameters were undertaken at 9.00 am, 4.00pm, 9.00 pm and 4.00am in eleven healthy subjects, observing the dawn to sunset fast of the holy Muslim fasting month of Ramadan. Measurements were repeated in an ordinary ‘non-fasting’ day. No statistically significant fluctuations were noted in prothrombin time, activated partial thromboplastin time, thrombin time, plasma fibrinogen, plasminogen, and tissue plasminogen activator (t-PA) either during Ramadan or in a non-fasting day. However, markedly elevated levels of the plasminogen activator inhibitor (PAI) activity were noted at 9.00 am in Ramadan and at 4.00 am on a non-fasting day. Both increases were determined after several hours overnight sleep; the waking time in Ramadan being 8.30 am and 4.30 am in non-Ramadan day. Thus the circadian variation in PAI activity levels are influenced more by sleep pattern rather than food intake or the normal activities of a working day.     

Effect of telavancin (Vibativ) on routine coagulation test results

Telavancin (Vibativ, Astellas Pharma US, Deerfield, IL) is a lipoglycopeptide antibiotic that has activity against gram-positive microorganisms, but also has the ability to bind to artificial phospholipids found in coagulation reagents. Normal pooled plasma was spiked with telavancin to obtain concentrations of 0, 12.5, 25, 50, 75, 100, 125, and 150 μg/mL of drug. Samples were tested using 3 different prothrombin time/international normalized ratio (INR) and activated partial thromboplastin time (aPTT) reagent systems, as well as for fibrinogen level, thrombin time, D-dimer level, dilute Russell viper venom time (DRVVT), protein C activity, and protein S activity. There was no effect of telavancin seen with non-phospholipid-dependent assays: fibrinogen level, thrombin time, and D-dimer testing. All INR and aPTT systems demonstrated concentration-dependent increases in clotting times, with Innovin (Siemens Healthcare Diagnostics, Deerfield, IL) INRs the most dramatic. False-positive DRVVT ratios started at 12.5 μg/mL of telavancin, with no effect on protein C or protein S levels until the telavancin level reached more than 100 μg/mL.