Simplified citrate anticoagulation for high-flux hemodialysis

In a randomized crossover trial, we compared a simple citrate anticoagulation protocol for high-flux hemodialysis with standard anticoagulation by low-molecular-weight heparin (dalteparin). Primary end points were urea reduction rate (URR), Kt/V, and control of electrolyte and acid-base homeostasis. Secondary end points were bleeding time at vascular puncture sites and markers of activation of platelets, coagulation, and fibrinolysis. Solute removal during citrate dialysis was excellent (URR, 0.71 +/- 0.06; Kt/V, 1.55 +/- 0.3) and similar to results of conventional bicarbonate hemodialysis anticoagulation with dalteparin (URR, 0.72 +/- 0.04; Kt/V, 1.56 +/- 0.2). Electrolyte control was effective with both anticoagulation regimens, and total and ionized calcium, sodium, potassium, and phosphate concentrations at the end of dialysis did not differ. Alkalemia was less frequent after citrate than conventional dialysis (pH 7.5 in 25% versus 62% of patients; mean pH at end of dialysis, 7.46 +/- 0.06 versus 7.51 +/- 0.07; P < 0.01). Bleeding time at puncture sites was shorter by 30% after citrate compared with dalteparin anticoagulation (5.43 +/- 2.80 versus 7.86 +/- 2.93 minutes; P < 0.001). Activation of platelets, coagulation, and fibrinolysis was modest for both treatments and occurred mainly within the dialyzer during dalteparin treatment and in the vascular-access region during citrate anticoagulation. Citrate-related adverse events were not observed. We conclude that citrate anticoagulation for high-flux hemodialysis is feasible and safe using a simple infusion protocol.

Effects of fixed low-dose warfarin on hemostatic factors in continuous ambulatory peritoneal dialysis patients

Increased coagulation factors found in dialysis patients may explain in part the high prevalence of thrombotic cardiovascular disease. Several studies showed low-dose warfarin is effective in decreasing coagulation factors and preventing thrombosis without increasing the risk of bleeding. To evaluate the effects of fixed low-dose warfarin therapy on thrombogenesis in continuous ambulatory peritoneal dialysis (CAPD) patients, 76 CAPD patients were assigned randomly to treatment and disease control groups. The treatment group received 2 mg of warfarin daily for 12 months. International normalized ratio (INR) of the prothrombin time and plasma levels of factor VII, D-dimer, von Willebrand factor (vWF), and plasminogen activator inhibitor-1 (PAI-1) were measured before and 3, 6, and 12 months after the start of medication. The same parameters were measured in 30 healthy volunteers at the beginning of the study and in the disease control group during the study period. Of 76 patients, 60 completed the study. Deaths from atherosclerotic cardiovascular disease (cerebral infarction or acute myocardial infarction) occurred in 1 patient in the treatment group (n = 29) and 3 in the disease control group (n = 31), which was not statistically significant. No major bleeding occurred during the study period. With administration of warfarin, there was a small increase in INR in the treatment group. CAPD patients at baseline had significantly higher plasma factor VII, D-dimer, vWF, and PAI-1 levels than normal controls. Warfarin therapy lowered plasma factor VII and D-dimer levels. No change was seen in vWF and PAI-1 levels. In the disease control group, these hemostatic factors showed no change during the study period. There was a negative correlation between serum albumin and INR in the treatment group during the study period. Fixed low-dose warfarin was effective in partially reversing the thrombogenic coagulation profile in CAPD patients without a big increase in the risk of bleeding.

PLATSAK, a potent antithrombotic and fibrinolytic protein, inhibits arterial and venous thrombosis in a baboon model

Antiplatelet-antithrombin-staphylokinase (PLATSAK) is a chimeric protein that was recombinantly produced in Escherichia coli cells. The protein was designed to target haemostasis at three different levels. It consists of staphylokinase for activation of fibrinolyis, the Arg-Gly-Asp sequence for the prevention of platelet aggregation, and an antithrombotic peptide for the inhibition of thrombin. The in vivo activity of PLATSAK was evaluated by assessing its effect on platelet deposition in a baboon model of arterial and venous thrombosis. Dacron vascular graft segments and expansion chambers, inserted as extensions into permanent femoral arteriovenous shunts, were used to simulate arterial and venous thrombosis, respectively. PLATSAK (3.68 mg/kg) was administered as a bolus 10 minutes before placement of the thrombogenic devices. Platelet deposition onto the graft surface and in the expansion chamber was imaged in real time with a scintillation camera as the deposition of 111In-labeled platelets. After 2 hours, platelet deposition in the graft segments and expansion chambers was inhibited by 50% and 85%, respectively, when compared to control studies. The activated partial thromboplastin time was lengthened to greater than 120 seconds. Interestingly, the level of fibrinogen degradation products in plasma did not increase after administration of PLATSAK. These results demonstrate that PLATSAK effectively inhibited platelet deposition in both arterial- and venous-type thrombosis in an animal model.

Short-chain fatty acid enemas stimulate plasminogen activator inhibitor-1 after abdominal aortic graft surgery: a double-blinded, placebo-controlled study

Colonic ischaemia may complicate aortic graft surgery with high mortality from associated colonic necrosis. Loss of the mucosal barrier function due to ischaemia may promote translocation of endotoxins with secondary systemic disseminated coagulation leading to multiple organ failure. Short-chain fatty acids (SCFAs) stimulate the microcirculation in the human rectum. The aim of this study was to investigate whether SCFA enemas influence systemic endotoxinaemia and fibrinolytic activity during and after elective aortic graft surgery for arteriosclerosis. Thirty-two patients were randomized to SCFA or placebo enemas twice daily from the day before surgery to 7 days after. Blood samples for endotoxin, plasminogen activator inhibitor-1 (PAI-1) activity, tissue-type plasminogen activator (t-PA) antigen, and cross-linked fibrin degradation products (XL-FDP) were drawn before, during, and 7 days after surgery. Four patients, two in each treatment group, developed postoperative endotoxinaemia. PAI-1 was significantly higher on days 2 and 4 in SCFA-treated patients, whereas t-PA was comparable Petween the groups. During the postoperative course, a progressive and near-identical XL-FDP increase was found in the two groups. In elective aortic graft surgery for arteriosclerosis, SCFA enemas likely stimulate systemic PAI-1 activity by promoting colonic tissue reperfusion following aortic unclamping. Endotoxinaemia and fibrinolytic shutdown are uncommon findings.

Relationship of cardiac troponin T and procoagulant activity in unstable angina

OBJECTIVE

The present study sought to determine the incidence of increased procoagulant activity in patients with unstable angina (UAP), and to evaluate the relationship between cardiac troponin T (cTnT) and molecular markers of hemostatic activation. Method. We studied 44 patients with UAP further classified by plasma cTnT levels. All patients received an antithrombotic therapy consisting of therapeutic doses of unfractionated heparin and acetylsalicylic acid. Quantitative levels of cTnT and plasma concentrations of fibrin monomers (FM), prothrombin fragments F1+2, thrombin antithrombin III complexes (TAT), plasminogen and alpha2-antiplasmin were sampled serially within the first 48 h.

RESULTS

Increased plasma concentrations of FM were detected in 45.5% of patients and were more frequently present among those with cTnT concentrations > or =0.1 ng/ml (13 of 18 vs 7 of 26 patients, p = 0.003). In these patients, mean plasma concentrations of FM were significantly higher than in patients with cTnT <0.1 ng/ml (7.93 +/- 2.3 vs 3.12 +/- 0.6 microg/ml, p = 0.02). There was a close relationship between plasma levels of cTnT and FM (r = 0.74, p <0.004), prothrombin fragments F1+2 (r = 0.71, p = 0.046) and a trend to significance was noted for TAT (r = 0.42, p = 0.055). No significant correlation was observed with markers of the fibrinolytic system (plasminogen and alpha2-anti-plasmin). Plasma levels of cTnT > or =0.1 ng/ml identified a concomitant increase of hemostatic markers with a sensitivity, specificity and positive predictive value of 65, 79, and 72% for FM, 63, 76, and 67% for prothrombin fragments F1+2, and 58, 66, and 39% for TAT, respectively.

CONCLUSIONS

In patients with UAP, cTnT identifies patients with increased procoagulant activity and is closely related to plasma levels of molecular markers of hemostatic activation. Therefore, cTnT alone or in combination with one of these markers may be helpful to identify patients requiring more potent antithrombin or antiplatelet therapy.

Possible mechanisms through which dietary pectin influences fibrin network architecture in hypercholesterolaemic subjects

It is suspected that not only fibrinogen concentration but also the quality of fibrin networks may contribute to cardiovascular risk. Evidence is accumulating that a "prudent" diet may protect against diseases associated with raised clotting factors. The effect of diet on fibrinogen is, however, still controversial. In a previous study performed in our laboratory, it was shown that dietary pectin influences fibrin network architecture in hypercholesterolaemic men without causing any changes in fibrinogen concentration. To elucidate the possible mechanisms, it was necessary to study the possibility that pectin may itself have indirect effects on fibrin network architecture. Pectin is fermented in the gastrointestinal tract to acetate, propionate, and butyrate. In humans, only acetate reaches the circulation beyond the liver. This investigation primarily examined the possibility that pectin may, through acetate, influence fibrin network architecture in vivo. The effects of pectin and acetate supplementation in hypercholesterolaemic subjects were compared. Furthermore, this study also aimed at describing the possible in vitro effects of acetate on fibrin network architecture. Two groups of 10 male hyperlipidaemic volunteers each received a pectin (15 g/day) or acetate (6.8 g/day) supplement for 4 weeks. Acetate supplementation did not cause a significant change in plasma fibrinogen levels. As in the pectin group, significant differences were found in the characteristics of fibrin networks developed in plasma after 4 weeks of acetate supplementation. Fibrin networks were more permeable (from 213+/-76 to 307+/-81 x 10(11) cm2), had lower tensile strength (from 23+/-3 to 32+/-9% compaction), and were more lyseable (from 252+/-11 to 130+/-15 minutes). These results strongly suggest that the effect of pectin on network architecture could partially be mediated by acetate. Progressive amounts of acetate were used in vitro to investigate the possibility that acetate may be directly responsible for changes that occurred in fibrin network architecture in the plasma medium. Results indicated that acetate influenced fibrin network architecture directly. From the results, it seems highly possible that acetate may be responsible in part for the beneficial effects of pectin supplementation in vivo. It is evident that pectin or acetate supplementation can be useful during the treatment or prevention of some clinical manifestations, especially those associated with raised total cholesterol and possibly also plasma fibrinogen.

Effects on hemostasis after two-year use of low dose combined oral contraceptives with gestodene or levonorgestrel

We studied 67 healthy women who were randomly allocated to receive third generation gestodene (Gynera) or second generation levonorgestrel (Microgynon 30) combination of low-dose estrogen oral contraceptives (OCs) for their hemostatic effects over 2 years. Hemostatic changes were apparent within 3 months of OC use. Hematocrit (Hct) was not affected, but hemoglobin (Hb) concentration decreased by 18 months. Shortened prothrombin time (PT) and activated plasma thromboplastin time (APTT) were associated with elevated fibrinogen within the 12-month use of both OCs. Factor VII was reduced only in Micro 30 during the 18 months of use. Enhanced thrombin-antithrombin (TAT)-complex level was seen at 18 months of Gynera use. Prothrombin fragment1+2 (F1+2) rise was seen at 3 months with Micro 30. Reduced antithrombin III (ATIII) activity was seen at 18 months with Gynera and at 24 months with Micro 30. Increased protein C activity was seen at 3 months and reduced protein S occurred at 18 months of Gynera use. Tissue plasminogen activator (t-PA) activity was enhanced for 6 months in both OCs with raised D-dimer levels for 12 months with Gynera and 6 months with Micro 30. Decreased t-PA antigen was seen at 18 months and decreased urokinaselike plasminogen activator (u-PA) antigen occurred throughout the 24 months of both OCs use. Enhanced u-PA activity was only seen in Gynera users. Elevated plasminogen levels were apparent throughout both OCs use. PAI-1 levels were significantly decreased with Micro 30. With Gynera, the decreased PAI-1 activity was seen only at 18 months and PAI-1 antigen at 12 months. No change in platelets and von Willebrand factor (vWF) were seen in long-term OC use except that beta-thromboglobulin (beta-TG) showed decreased trends reaching statistical significance by 18 and 24 months of Micro 30 use and by 24 months of Gynera use. A further significant decrease in beta-TG, u-PA antigen, ATIII, and protein S levels were seen 3 months after pill stoppage compared with pretreatment levels. Activated protein C resistance (APCR) was negative in all subjects before and during OC use. The study indicated dynamic balance between coagulation and fibrinolysis with no endothelial activation. However, because some hemostatic markers showed wide fluctuations during OC use, a longer term study is warranted to investigate any adverse hemostatic changes that might enhance the risks of venous thromboembolism in Asian subjects known to be less prone to thrombosis.

Alterations in fibrin detected in coronary sinus blood after heparin and coronary angiography with a nonionic contrast agent (iohexol)

Although heparin and some radiographic contrast agents inhibit coagulation, thrombi can still form in their presence. The chemical environment in which a thrombus forms affects fibrin structure that may alter the ability of the thrombus to be lysed. Therefore, we assessed changes in fibrin structure in 13 patients referred for coronary angiography. Blood was obtained from the femoral vein, femoral artery, ascending aorta, left main coronary artery (LMCA), and coronary sinus (CS) before, during, and after coronary angiography was performed with iohexol. The number of fibrin monomers per fiber cross section was determined by turbidity measurements of fibrin gels formed from plasma samples. At baseline there was no difference in the number of fibrin monomers per fiber cross section in plasma gels generated from the different sampling sites. After iohexol administration, there was a significant decrease in the number of fibrin monomers per fiber cross section at the sampling sites ranging from - 13% to -25% compared with the respective baseline values with the largest change in the LMCA CS (51+/-16 to 38+/-15, p <0.025). Transcardiac (LM - CS value) changes in the number of fibrin monomers per fiber cross section were dependent on the timing of the sample collection in the CS. In 7 patients, the CS sample was collected approximately 2 minutes after injection of contrast material and there was no transcardiac difference. When the CS sample was obtained during contrast injection (n=6) a large transcardiac change occurred (44+/-10 to 32+/-14, p=0.01). These data show transient changes in fibrin structure during coronary angiography with iohexol. The thinner fibers formed in the presence of iohexol were more resistant to fibrinolysis.

Aprotinin in pediatric cardiac operations: a benefit in complex malformations and with high-dose regimen only

BACKGROUND

The benefits and the current indications of aprotinin in congenital operations are not well defined. At present there are only a few studies available that have investigated a small number of patients in several heterogeneous groups of malformations.

METHODS

We investigated efficacy and safety of aprotinin in three groups of children < 15 kg, presenting with isolated ventricular septum defect (n = 60), tetralogy of Fallot (n = 52), and transposition of the great arteries (n = 56). Low-dose aprotinin regimen A1 (500,000 KIU in pump prime only) and high-dose aprotinin A2 (50,000 KIU/kg during induction of anesthesia, 50,000 KIU/kg in pump prime, and 20,000 KIU/h continuous infusion) were compared to a control group A0 (without aprotinin) regarding perioperative blood loss, transfusion requirements, and effects on the coagulation system.

RESULTS

The most common coagulation tests of aprotinin-treated patients and the platelet numbers were comparable with those of control patients preoperatively and 15 minutes after protamine administration. A significant dose-dependent reduction in fibrin-fibrinogen split products was observed at the end of cardiopulmonary bypass in the majority of aprotinin-treated patients with transposition. In patients with ventricular septum defect and Fallot, no significant difference in blood loss and transfusion requirements could be observed between patients with or without aprotinin and no difference was observed between low- and high-dose regimen. In transposition of the great arteries, high-dose aprotinin led to significant reduction of blood loss (p = 0.02) and postoperative blood transfusion (p = 0.003). Severe side effects as a result of administration of aprotinin were not observed.

CONCLUSIONS

High-dose aprotinin reduces blood loss and transfusion requirement only in complex congenital cardiac operations; therefore aprotinin cannot be recommended as a blood conservation agent in routine pediatric operations.

Digestion of 125I-labelled plasmin-derived fibrin degradation products by neutrophil lysosomal enzymes

The cellular components of the blood, which become associated with fibrin through specific cellular adhesive processes, play a significant role in the breakdown of fibrin. Fibrinolysis by neutrophil elastase and cathepsin G occurs in a manner distinct from that produced by plasmin. This study demonstrates that neutrophil lysosomal enzyme activity further degrades the end products of plasmic fibrin degradation into low-molecular-weight material, followed by reassembly of higher-molecular-weight products in a process dependent on calcium and factor XIII. Although one of the reformed products has a similar molecular weight to D-dimer and is recognized by a monoclonal antibody raised against D-dimer, its isoelectric point indicates it to be distinctly different from plasmin-derived D-dimer. Processing of the end products of plasmic fibrin degradation by neutrophils may have the potential for modulating the immune response as well as compromising the predictive value of tests measuring D-dimer.

Homozygous type I plasminogen deficiency

Homozygous type I plasminogen (Plg) deficiency has not been described in human subjects so far. Ligneous conjunctivitis is a rare and unusual form of chronic pseudomembranous conjunctivitis of unknown etiology. Here we report for the first time on homozygous type I Plg deficiency in three unrelated female patients who suffered from ligneous conjunctivitis and additional pseudomembranous lesions of other mucous membranes. The disease is caused by massive fibrin depositions within the "extravascular space" of mucous membranes because of absent clearance by plasmin. Infusions of albumin, fresh frozen plasma, or Lys-plasminogen (Lys-Plg) into two of the three patients revealed normal Plg activation capacity in these patients. The absence of fibrinolytic activity could therefore be shown to be due to Plg deficiency. Similar studies in the third patient have not been completed. In the two patients studied so far, infusions of Lys-Plg resulted in prompt and adequate Plg recovery with a short half-life and high amounts of plasmin-antiplasmin complexes and D-dimer. One patient additionally revealed an inherited partial factor XII deficiency. Functionally, this factor XII deficiency did not interfere with Plg activation. However, there may be a pathway of Plg activation in this patient via the prekallikrein C1-INH system.

Hemostatic parameters in sepsis patients treated with anti-TNF alpha-monoclonal antibodies

Tumor necrosis factor-alpha (TNF alpha) is a central mediator in the pathogenesis of sepsis. It also interferes with the hemostatic system and exerts and a net procoagulant effect. Since TNF alpha may contribute to thrombotic complications in sepsis patients, we determined markers of thrombin activation, parameters of the fibrinolytic system (D-dimer, tissue plasminogen activator antigen (tPA) urinary type plasminogen activator antigen (uPA), plasminogen activator inhibitor antigen (PAI-1) and von Willebrand factor antigen (vWF) in 30 patients with sepsis or septic shock. All patients were treated with standard therapy, but 14 patients were treated additionally with an anti-TNF alpha monoclonal antibody (MAK 195F); 16 patients served as historical controls. No significant effect of the antibody on the parameters of the hemostatic system could be determined. Our data speak against a modulation of coagulation or the fibrinolytic system by the monoclonal anti-TNF alpha antibody MAK 195F in this cohort of sepsis patients.

Acetylsalicylic acid may protect the patient by increasing fibrin gel porosity. Is withdrawing of treatment harmful to the patient?

The effect of acetylsalicylic acid in preventing cardiovascular complications is ascribed to acetylation of the enzyme cyclo-oxygenase thereby inhibiting prostaglandin synthesis. Acetylsalicylic acid, however, also acetylates fibrinogen. In the present pilot study, we investigated the permeability, i.e. porosity, of the fibrin gel in male patients with stable angina pectoris treated with this drug before and at 1 and 2 weeks after withdrawal. Ten patients were treated with 75 mg and eight with 160 mg. The results were compared to those in seven untreated healthy controls. Bleeding times were longer during treatment and were reduced after withdrawal indicating patient compliance. Fibrin gels were more porous during treatment although there were large inter-individual variations in porosity. One week after withdrawal, the porosity was reduced by 30 41%, i.e. the network became tighter (75 mg group P = 0.001; 160 mg group P = 0.002). The tightness was more pronounced after withdrawal than in the untreated controls. In conclusion, the protective effect of acetylsalicylic acid may be ascribed to its effect not only on platelets but also on fibrinogen. The withdrawal of acetylsalicylic acid may clause a markedly reduced fibrin gel porosity that we assume is disadvantageous in patients with cardiovascular disease.

Increased plasma concentration of fibrin monomer in acute myocardial infarction with early reperfusion

OBJECTIVE

To assess whether plasma fibrin monomer (FM) concentration, a marker of thrombin activity, is increased in the first hours after acute coronary occlusion and whether there are differences between patients with and without early reperfusion.

DESIGN

Thirty-five consecutive patients with acute myocardial infarction (AMI) and early coronary angiography were studied prospectively.

METHODS

Plasma FM samples taken on admission (< 6 h after onset of chest pain) and 6-14 h after onset of chest pain were analysed using a specific enzyme immunoassay. All of the patients were anticoagulated with heparin intravenously.

RESULTS

Of the 35 patients, 28 had angiographically documented reperfusion within the first 6 h, whereas seven patients had no early reperfusion. FM concentrations were measured in the reference range (< or = 3.6 mg/l) within the first 6 h in 32 of the 35 patients. At 6-14 h FM concentrations were elevated in the reperfusion group (median 4.56 mg/l), but not in the group without reperfusion (median 1.6 mg/l, P = 0.0063). Using a threshold value of 3.0 mg/l, sensitivity and specificity of FM for the non-invasive recognition of early reperfusion were 78 and 83%, respectively. The specificity was similar to that for troponin T and higher than the creatinine kinase MB specificity.

CONCLUSIONS

FM plasma concentrations are elevated in patients with AMI and early reperfusion. With a single blood sample 6-14 h after onset of chest pain, FM analysis is useful for the non-invasive detection of early reperfusion after AMI.

Streptokinase inhibits pulmonary tumor seeding in an animal experimental model

One aspect of the metastatic process involves entrapment of tumor cells within the microcirculation of organs in a "fibrin-platelet mesh." We postulate that destruction of this mesh by fibrinolysis might discourage tumor seeding, thereby inhibiting metastasis. To study this hypothesis, the effect of intravenous streptokinase on pulmonary tumor seeding was examined in a rodent model. In vitro experiments demonstrated that streptokinase had no cytotoxic or cytostatic effect on the Mtln3 cell line. Pharmacokinetic studies showed that at 30,000 U/kg, streptokinase caused systemic fibrinolysis in the Fischer rat, as demonstrated by the thrombin time and fibrin plate lysis assay. Streptokinase administered at this dose, 30 min after tumor cell injection, caused a significant decrease in pulmonary tumor seeding (median 23.0 in the streptokinase-treated group vs. 67.5 in untreated controls, P < 0.0001, Mann-Whitney U-test). Analysis of fibrin degradation products in the streptokinase-treated group suggested that this effect might be secondary to fibrinolysis. The implications of these findings are discussed.

[An analysis of a disorder in the fibrin-forming phase in virtually healthy middle-aged and elderly subjects by using the ancistron test]

Damages in the fibrin-formation phase initiated by activation of the blood coagulation system and fibrinolysis and promoted by interaction between fibrinogen and its derivatives (dissolved fibrinogen, products of fibrin and fibrinogen lysis) and by the presence of various blood coagulation inhibitors were found in 34% of practically sound old people and in 47% of people of senile age. It is shown very significant to apply the "ancistrone time" test developed on the basis of enzyme ancistrone-H isolated from the venom of snake Agkistrodon halys halys for estimating the fibrin-formation phase both on the model system and in practically sound people of old and senile age. The ancistrone test permits rapidly (for 30-60s) obtaining qualitative and quantitative characteristic of the fibrinogen level in the blood plasma, of the products of fibrin and fibrinogen lysis, of the blood coagulation inhibitors.

Influence of heparin on fibrinogen and D-dimer plasma levels in acute myocardial infarction treated with streptokinase

The purpose of this study was to investigate whether, to what extent, and through which mechanisms intravenous heparin, administered before and after streptokinase, affects the plasma levels of D-dimer and fibrinogen in myocardial infarction. Data concerning mortality and incidence of coronary recanalization in patients receiving heparin and thrombolytic therapy after acute myocardial infarction are controversial; furthermore, the mechanisms through which heparin acts in combination with thrombolytic therapy are unclear. Thirty-eight patients with acute myocardial infarction treated with streptokinase were considered. Nineteen of them received, immediately before the beginning of thrombolytic treatment, a bolus of heparin (100 U.kg-1 intravenously) and, 2 h later, intravenous heparin in doses raising the partial thromboplastin time to 2-2.5 times the normal value (Group 1); the remaining 19 did not receive anticoagulant treatment (Group 2). Multiple determinations of plasma D-dimer and fibrinogen levels were obtained in all patients before, and in the seven days following thrombolytic treatment. Six hours after streptokinase, fibrinogen decreased from 304 +/- 34 to 61 +/- 34 mg.dl-1 in Group 1 and from 312 +/- 29 to 38 +/- 21 mg.dl-1 in Group 2 (P < 0.02 versus Group 1). The same difference between groups persisted at the 12th and at the 18th hour. D-dimer values, from 0.5 +/- 0.1 microgram.dl-1 in Group 1 and 0.4 +/- 0.1 microgram.dl-1 in Group 2, increased at the 1st hour to 37.2 +/- 36.5 micrograms.dl-1 and 52.2 +/- 39.8 micrograms.dl-1, respectively. A peak value was reached in both groups at the 6th hour, which was followed by a slow decrease.(ABSTRACT TRUNCATED AT 250 WORDS)

Aprotinin reduces cardiopulmonary bypass-induced blood loss and inhibits fibrinolysis without influencing platelets

Cardiopulmonary bypass (CPB) induces a bleeding defect which leads to enhanced blood loss. A double-blind study was carried out comparing aprotinin with placebo in patients undergoing re-operation for heart valve replacement. The results confirm that aprotinin is effective at reducing such loss. In the placebo treated group, significant increases were observed, during CPB, in the plasma concentrations of fibrinolytic activity, tissue plasminogen activator antigen, D-dimer, and beta-thromboglobulin. Platelet counts fell within 5-10 min of the patients going onto CPB, but this could be accounted for by the dilutional effect of the extracorporeal circuit. Inhibition of responsiveness of platelets, as judged by aggregometry, was significant only at the end of bypass when collagen was the agonist and after protamine reversal when ristocetin was the agonist. CPB did not enhance the release, into the circulation, of glycocalicin (a proteolytic fragment of glycoprotein Ib). In the aprotinin-treated group, the formation of fibrin degradation products as measured by D-dimer was inhibited. However, aprotinin did not influence the change in platelet count, suppress beta-thromboglobulin release from platelets, prevent the inhibition of platelet function or influence the concentration of plasma glycocalicin during the study period. These observations confirm that CPB leads to a fibrinolytic state and less responsive platelets. This study also indicates that aprotinin-induced reduction in blood loss is associated with inhibition of plasmin-mediated fibrin digestion and that the mechanism by which aprotinin reduces blood loss is not via protection of platelets during CPB.

Hemostatic activation during cardiopulmonary bypass with different aprotinin dosages in pediatric patients having cardiac operations

The effect of high-dose aprotinin treatment on hemostatic activation during cardiopulmonary bypass in pediatric patients having cardiac operations was investigated. Sixty patients weighing less than 10 kg undergoing cardiac operations for different types of congenital heart diseases were studied: 20 patients were treated with aprotinin 2 x 15,000 KIU/kg, 20 patients with 2 x 30,000 KIU/kg, and 20 patients without aprotinin treatment served as the control group. Different split products of fibrinogen and/or fibrin and the fibrinolytic activity on fibrin plates were measured to assess fibrinolytic activation. F1/F2 prothrombin fragments, thrombin-antithrombin III-complex, and fibrin monomers were measured to estimate thrombin activation. There was a significant dose-dependent reduction in fibrin-fibrinogen split product formation during cardiopulmonary bypass: In the high-dose aprotinin group the concentration of the split products at the end of bypass was 1.5 +/- 0.6 micrograms/ml, compared with 3.4 +/- 3.0 micrograms/ml in the low-dose aprotinin group and 6.7 +/- 3.5 micrograms/ml in the control group (p < 00.5). Fibrinolytic activation on fibrin plates was also significantly reduced by aprotinin. Fibrin monomer formation was significantly diminished at the end of cardiopulmonary bypass in the high-dose group: 9.2 +/- 5.2 micrograms/ml compared with 21.6 +/- 14 micrograms/ml in the control group (p < 00.5). Elastase in complex with alpha 1-protease inhibitor at the end of bypass was increased to the same amount in the three groups: 784 +/- 278 ng/mL (control group), 693 +/- 189 ng/ml (low-dose aprotinin), and 719 +/- 270 ng/mL (high dose aprotinin) (no significant difference). Blood loss 6 hours postoperatively was significantly (p < 00.5) less in the high-dose group (99 +/- 32 ml/m2) than in the control group (164 +/- 87 ml/m2; low-dose group: 160 +/- 106 ml/m2). These observations suggest an attenuation of hemostatic activation during cardiopulmonary bypass with less plasmin formation and, because of inhibition of contact activation, less thrombin generation with aprotinin treatment. Thus the thrombotic-thrombolytic equilibrium is kept more balanced after cardiopulmonary bypass. High-dose aprotinin treatment is recommended for pediatric patients undergoing cardiac operations.

[The thromboplastic activity of normal and tumorous human tissues]

The study was made of thromboplastic activity of normal, pathological and tumor human tissues using a hemocoagulatory test-system specifically sensitive to apoprotein III-containing membrane structures. It is established that thromboplastic activity of membrane fragments can be inhibited by native cell components. Blood coagulation and fibrin deposition in tissues can go without cell damaging under initiation by increased permeability of vascular walls and plasma contact with surface of the cells located extravascularly.

[The use of picotamide in nephropathy with mesangial IgA deposits. The effect on thromboxane generation]

IgA nephropathy (Berger's disease) is one of the commonest forms of glomerular disease, not rarely progressing to renal failure. Hemostatic system activation may play a role in the development of glomerular injury. In a series of 12 adult patients affected with IgA nephropathy we have observed increased plasma levels of D-dimer, a stable end-product of cross-linked fibrin degradation that is considered a reliable index of blood clotting activation, as well as "in vitro" raised generation of thromboxane, the main platelet product of arachidonic acid metabolism that seems to play an important role in glomerulosclerosis. Picotamide, a novel antiplatelet drug acting as thromboxane synthase inhibitor as well as thromboxane receptor antagonist, administered for 8-12 weeks, was effective in reducing thromboxane generation. We conclude that picotamide may be useful in the management of glomerular nephropathy.

Hemorrhagic events during therapy with recombinant tissue-type plasminogen activator, heparin, and aspirin for acute myocardial infarction. Results of the Thrombolysis in Myocardial Infarction (TIMI), Phase II Trial

OBJECTIVES

To assess the effects of invasive procedures, hemostatic and clinical variables, the timing of beta-blocker therapy, and the doses of recombinant plasminogen activator (rt-PA) on hemorrhagic events.

DESIGN

A multicenter, randomized, controlled trial.

SETTING

Hospitals participating in the Thrombolysis in Myocardial Infarction, Phase II trial (TIMI II).

INTERVENTIONS

Patients received rt-PA, heparin, and aspirin. The total dose of rt-PA was 150 mg for the first 520 patients and 100 mg for the remaining 2819 patients. Patients were randomly assigned to an invasive strategy (coronary arteriography with percutaneous angioplasty [if feasible] done routinely 18 to 48 hours after the start of thrombolytic therapy) or to a conservative strategy (coronary arteriography done for recurrent spontaneous or exercise-induced ischemia). Eligible patients were also randomly assigned to either immediate intravenous or deferred beta-blocker therapy.

MEASUREMENTS

Patients were monitored for hemorrhagic events during hospitalization.

MAIN RESULTS

In patients on the 100-mg rt-PA regimen, major and minor hemorrhagic events were more common among those assigned to the invasive than among those assigned to the conservative strategy (18.5% versus 12.8%, P less than 0.001). Major or minor hemorrhagic events were associated with the extent of fibrinogen breakdown, peak rt-PA levels, thrombocytopenia, prolongation of the activated partial thromboplastin time (APTT) to more than 90 seconds, weight of 70 kg or less, female gender, and physical signs of cardiac decompensation. Immediate intravenous beta-blocker therapy had no important effect on hemorrhagic events when compared with delayed beta-blocker therapy. Intracranial hemorrhages were more frequent among patients treated with the 150-mg rt-PA dose than with the 100-mg rt-PA dose (2.1% versus 0.5%, P less than 0.001). The extent of the plasmin-mediated hemostatic defect was also greater in patients receiving the 150-mg dose.

CONCLUSIONS

Increased morbidity due to hemorrhagic complications is associated with an invasive management strategy in patients with acute myocardial infarction. Our findings show the complex interaction of several factors in the occurrence of hemorrhagic events during thrombolytic therapy.

[The action of regulator peptides with different biological activities on the process of fibrin-monomer polymerization and on nonenzymatic fibrinolysis]

It is shown that preparations of regulatory peptides (RP): interleukin-1, thymoptin, and the endogenous nonpeptide opioid salsalinol produce a marked depolymerization effect on the fibrin-monomer and display nonenzymatic fibrinolytic activity in relation to unstabilized fibrin. Preparations of regulatory peptides thymalin and diphensin of rabbits intensify fibrin polymerization. A single intravenous infusion of diphensin preparation inhibits nonenzymatic fibrinolysis of blood plasma in vivo and in vitro. Repeated intramuscular injections of the immunoactive preparation thymoptin intensify the fibrinolytic properties of blood plasma in rats.

[The effect of tuftsin on fibrin polymerization in vitro and on the hemostatic system when administered intravenously to healthy animals]

Taftsine tetrapeptide has antiprocoagulatory properties in vitro in the presence of plasma. Taftsine exerts depolymerization influence on fibrin monomer in concentrations of 10(-1) to 10(-9) mg/ml. At intravenous injection in doses of 1 mg and 300 ug/kg, taftsine causes the increase in plasma clotting time and significant increase in enzymatic and nonenzymatic fibrinolysis. The effect can be observed during 120 min after injection of the peptide.