Low-density lipoprotein receptor-related protein 1 polymorphism 663 C > T affects clotting factor VIII activity and increases the risk of venous thromboembolism.

BACKGROUND: Clotting factor (F) VIII is an independent risk factor for primary and recurrent venous thromboembolism (VTE). The causes for high plasma FVIII levels are not fully understood, but an involvement of genetic factors has been demonstrated. A multifunctional endocytic receptor, low-density lipoprotein receptor-related protein 1 (LRP1), mediates cellular uptake and subsequent degradation of FVIII and may contribute to variations in FVIII levels. OBJECTIVE: We assessed the association of a genetic variation of LRP1 (663C > T) with basal FVIII levels and the risk of venous thrombosis in a group of high-risk patients and in healthy controls. PATIENTS AND METHODS: One hundred and fifty-two patients with a history of recurrent VTE (median age 56 years, 47% women) were compared with 198 age- and sex-matched controls (median age 53 years, 50% women). The LRP1 663C > T genotype was analyzed by mutagenic separated polymerase chain reaction assay and heterozygosity was confirmed by sequence analysis. RESULTS: LRP1 663C > T genotype distribution differed significantly between patients (663CC n = 138, 663CT n = 14) and controls (663CC n = 190, 663CT n = 8; P = 0.048). In multivariable linear regression analysis including LRP1 663C > T, ABO blood group, von Willebrand factor antigen, C-reactive protein and age, LRP1 663CT was independently associated with FVIII activity (P = 0.02). LRP1 663CT was also associated with increased odds for VTE following adjustment for blood group O, FV Leiden and the prothrombin variation 20210G > A in multivariate analysis (odds ratio 3.3, 95% CI 1.3-8.5). CONCLUSIONS: According to our data the LRP1 663C > T polymorphism influences plasma FVIII levels independently of blood group, C-reactive protein and von Willebrand factor and is significantly associated with the risk of VTE.

C-reactive protein 3' UTR +1444C>T polymorphism in patients with spontaneous venous thromboembolism.

OBJECTIVE: Data on C-reactive protein (CRP) as a risk indicator of venous thromboembolism are conflicting. A recent study reported higher CRP levels in homozygous carriers of a novel CRP gene polymorphism at the 3' UTR (CRP +1444C>T). We investigated, whether homozygosity for CRP +1444C>T is associated with an increased risk of spontaneous venous thromboembolism (VTE). METHODS AND RESULTS: CRP +1444C>T genotype and plasma levels were assessed in 128 patients with deep venous thrombosis (DVT, 70 females/58 males), 105 with pulmonary embolism (PE, 58 females/47 males) and 122 healthy individuals (60 females/62 males). CRP +1444TT was significantly associated with increased CRP plasma levels in healthy individuals. CRP +1444TT was more frequent (14%) among controls than DVT patients (9%, p=0.26) or PE patients (6%, p=0.05), respectively. No significant deviation from Hardy-Weinberg equilibrium was observed in patients (p=0.8) or controls (p=0.3), respectively. CRP +1444C>T was not significantly associated with CRP levels in patients with VTE. CONCLUSIONS: Homozygous carriers of the CRP 3' UTR +1444C>T polymorphism do not have a significantly increased risk of VTE. Our data support the assumption that a clinically relevant association between CRP and VTE is missing.

Decreased protein C levels in patients with insulin-dependent type I diabetes mellitus.

The plasma levels of protein C were investigated in 54 type I diabetic patients without retinopathy and in 14 diabetic patients with diabetic retinopathy and compared with the findings in 35 sex- and age-matched healthy control subjects. In the total group of type I diabetic patients, protein C was significantly less than in the controls. The lowest levels of protein C were found in diabetic patients with the poorest metabolic control. Protein C levels showed a significant negative correlation with the blood glucose levels, but they were not correlated with hemoglobin A1c (HbA1c). Although patients with retinopathy showed the least decrease of the plasma level of protein C among the diabetic subjects, the ratio of protein C to factor II was significantly decreased compared with the control subjects. Because the levels of coagulation factor II were not reduced in diabetic patients, the reduction of protein C seems to be caused, not by reduced synthesis in the liver, but more likely by an increased clearance from the blood plasma. The decrease of protein C in the plasma of type I diabetic patients indicates an abnormal, probably hypercoagulable, hemostatic situation in this disorder.

The effect of near-normoglycemic control on plasma factor VIII/von Willebrand factor and fibrin degradation products in insulin-dependent diabetic patients.

Diabetic patients have elevated plasma levels of factor VIII/von Willebrand factor (F VIII/vWF), and such elevations have been linked to vascular endothelial injury. In a prospective study we investigated the effect of metabolic regulation on the plasma levels of F VIII/vWF and cross-linked fibrin degradation products (XL-FDP), an indicator of intravascular coagulation, in 15 insulin-dependent diabetic patients who had no demonstrable vascular abnormalities. Eight patients had newly diagnosed diabetes, and 7 had been diabetic for an average of 12 yr. The patients were tested before and 1, 2, 4, and 8 weeks after the start of a structured diabetes education and care program, including introduction of a basal-bolus form of insulin treatment. Treatment for 8 weeks resulted in a highly significant improvement of metabolic control [hemoglobin Aic, 11.1 +/- 1.3% (+/- SD) vs. 6.8 +/- 1.0%; plasma fructosamine, 4.8 +/- 1.0 vs. 2.9 +/- 0.7 mmol/L; plasma glucose, 13.5 +/- 4.2 vs. 6.3 +/- 2.2 mmol/L; P less than 0.0001, respectively]. Compared to age- and sex-matched normal subjects, plasma activity of factor VIII (F VIII:C) was significantly elevated in the diabetic patients initially (1.5 +/- 0.6 vs. 1.0 +/- 0.1 x 10(3) U/L; P less than 0.01). After 2 weeks of intensified therapy it was 1.1 +/- 0.4 x 10(3) U/L. The mean plasma vWF value also was significantly elevated initially [vWF antigen, 1.8 +/- 0.7; normal group, 0.9 +/- 0.1 x 10(3) U/L (P less than 0.01); vWF ristocetin cofactor activity, 1.9 +/- 0.9; normal group, 1.0 +/- 0.3 x 10(3) U/L (P less than 0.001)] and decreased significantly after only 1 week of therapy. In the following 7-week period plasma vWF remained near normal. Plasma XL-FDP levels were elevated in all patients initially (190 +/- 150; normal group, 35 +/- 30 micrograms/L): the value was most abnormal in the patients with newly diagnosed disease (300 +/- 150 micrograms/L), indicating intravascular fibrin formation. The mean XL-FDP level declined significantly in the patients with newly diagnosed diabetes after 1 week of therapy; in the other patients, however, XL-FDP levels remained slightly elevated. In all 15 patients the plasma F VIII:C and XL-FDP levels were correlated significantly at all times. The plasma vWF and XL-FDP levels were correlated after 1, 2, 4, and 8 weeks of treatment as were the plasma vWF levels and glucose concentrations before and 1 and 2 weeks after the start of treatment program.(ABSTRACT TRUNCATED AT 400 WORDS)

Homo- and heterogeneous forms of human factor VIII.

In order to determine the molecular size of human F VIII as found in fresh plasma and as found in fresh-frozen plasma and in cryoprecipitate and to study the relationship of the factor-related properties, namely F VIII:C, F VIIR:Rcof and F VIIIR:Ag to F VIII, the factor's elution pattern on Sephacryl 1000 was investigated. When fresh plasma was chromatographed on this gel, F VIII eluted in a single sharp peak with all three F VIII-related activities appearing in the separation range of the gel column. The molecular weight of F VIII was calculated to be higher than 8 X 10(5). When fresh-frozen plasma was chromatographed on this gel, the elution pattern was identical to that of fresh plasma with the single exception that in several samples F VIII eluted in a broader peak tailing to higher molecular forms. When cryoglobulin fraction of fresh-frozen plasma was chromatographed, F VIII showed distinct heterogenicity in the elution pattern with respect to molecular size and relationship to the F VIII-related properties. Chelation of the endogenous plasma Ca-ions by citrate was found to have no influence on the factor's elution pattern.

The influence of thrombin on the clotting activity of factor VIII. A study with insolubilized thrombin.

An investigation of the influence of thrombin on the clotting activity of factor VIII was made. Purified factor VIII and different amounts of thrombin complexed to Sepharose 4 B were mixed and incubated for various periods of time. The factor VIII activities of these incubation mixtures were determined by the one- and two-stage analytical procedures in the presence of the thrombin-sepharose and in its absence following the latter removal from the test sample by filtration. The results so obtained confirm the view that thrombin inactivates factor VIII. Evidences for a thrombin-induced potentiation of the factor VIII activity, seen only in the thrombin-sepharose containing test samples analyzed by the one-stage method, are here interpreted as thrombin-effects peculiar to this factor VIII test system and not as potentiation by thrombin of the factor itself.

The influence of thrombin on the platelet-aggregating activity of human factor VIII. A study with insolubilized thrombin.

A study was made of the influence of thrombin on the platelet-aggregating activity of human factor VIII with Ristocetin as cofactor. Purified factor VIII and different amounts of a thrombin-Sepharose 2B complex were mixed and incubated for various periods of time. The factor VIII-related platelet-aggregating activities of the filtrates of the incubation mixtures were determined in a test system using formalin-fixed platelets and Ristocetin as cofactor. The results so obtained indicate that thrombin inactivates the platelet-aggregating activity of factor VIII. The filtrates of the incubation mixtures were also tested by a two-stage test system for the clotting activities. Comparison of the influence of thrombin on the clotting- and the platelet-aggregating activities of factor VIII is presented and discussed.

Early activation of hemostasis during cardiopulmonary bypass: evidence for thrombin mediated hyperfibrinolysis.

In 14 consecutive patients undergoing cardiopulmonary bypass for coronary bypass surgery the time course of coagulation and fibrinolysis markers were measured, e. g. plasma levels of thrombin-antithrombin III (TAT) complexes, cross-linked fibrin degradation products (XIFDP) and plasmin-alpha 2-antiplasmin complexes (PAP). TAT levels exceeded the 90% baseline percentile already during CPB (after opening of aortic clamp) in 10 patients, whereas PAP and XIFDP exceeded their 90% percentile in only one patient at this time. Concerning fibrinolysis markers PAP and XIFDP the majority of patients showed elevations higher than their 90% baseline percentile only 1 h postoperation. Correlation analysis revealed significant dependencies between TAT levels during and at the end of CPB and PAP levels 1 h postoperation (R = 0.55 and R = 0.56 respectively). Furthermore, 1 h postoperation XIFDP levels were significantly correlated with both TAT and PAP. Peak XIFDP levels at the same time correlated with blood loss via thoracic drains (R = 0.56). Thus, we suggest that hyperfibrinolysis in patients undergoing CPB is at least partly due to hypercoagulation. Clinically, this may implicate that intensified anticoagulation could prevent hyperfibrinolysis and reduce postoperative blood loss.

Haemostatic abnormalities persist despite glycaemic improvement by insulin therapy in lean type 2 diabetic patients.

Diabetes mellitus is associated with disturbances of the hemostatic system, which might contribute to the development of diabetic vascular disease. We investigated the effect of metabolic improvement by insulin therapy on the haemostatic system in 61 patients with type 2 diabetes mellitus and secondary sulfonylurea failure compared with 45 healthy control subjects matched for age, sex and BMI. Median age was 65, median diabetes duration 10 years. Median HbA1c (10%) and fructosamine (4.0 mM) levels were elevated before induction of therapy and decreased significantly within 6 months of insulin treatment to 7.5% and 3.0 mM, respectively (p < 0.0001). Compared with control subjects, median plasma levels of fibrinogen (317 vs 286 mg/dl), coagulation factor VII activity (1.1 vs 0.89 U/l), von Willebrand factor (1.6 vs 1.3 U/l), D-dimer (105 vs 86 micrograms/l), protein C:Ag (1.24 vs 0.95 U/l), total protein S:Ag (1.15 vs 0.91 U/l), and antithrombin III activity (1.17 vs 1.08 U/l) were significantly elevated. Levels of free protein S were not different from control values. No significant decline of coagulation parameters could be recorded during insulin therapy. Patients with diabetic vasculopathy had higher levels of D-dimer than those without (133 vs 76 micrograms/l before, 109 vs 88 micrograms/l during therapy), whereas the other haemostatic parameters were not different. Our data indicate a significant activation of the coagulation system in diabetic patients with secondary failure to sulfonylurea drugs, with signs of a prethrombotic state and endothelial cell disturbance.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of insulin treatment on the balance between tissue plasminogen activator and plasminogen activator inhibitor-1 in type 2 diabetic patients.

Beside hypercoagulation and hyperactivated platelets disturbances of the fibrinolytic system towards hypofibrinolysis have been reported to be associated with both glycemic and lipidemic derangement in diabetic patients. In the present prospective follow-up study the effect of 16 weeks insulin treatment and glycemic regulation on plasma levels of tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1), the main regulators of fibrinolysis, was investigated in 19 type-2 diabetic patients with secondary failure to sulphonylureas. A similar glycemic regulation was obtained in a control group of 10 type 2 diabetic patients with sufficient metabolic response to strict dietary treatment and continuation of sulphonylurea treatment. Compared to 27 healthy subjects levels of tPA and PAI-1 were not significantly increased in type 2 diabetic patients before metabolic intervention. Although a hypofibrinolytic state due to an increase of PAI-1 levels was previously reported in obese hyperinsulinemic patients, no effect of insulin treatment on both tPA- and PAI-1 levels was observed in the present study including patients with only slightly increased body mass index (median 26.0 kg/m2). By correlation analysis PAI-1 levels were significantly related to serum cholesterol (R = 0.52) and glycemic control (glucose R = 0.41) in the whole group of diabetic patients at entry and in both subgroups after 16 weeks of treatment (insulin group: cholesterol R = 0.46, HbA1c R = 0.51; sulphonylurea group: cholesterol R = 0.59, HbA1c R = 0.58). In healthy subjects tPA and PAI-1 was correlated to serum insulin (R = 0.54, R = 0.56) and triglycerides (R = 0.46, R = 0.40).(ABSTRACT TRUNCATED AT 250 WORDS)

Similar effects of atorvastatin, simvastatin and pravastatin on thrombogenic and inflammatory parameters in patients with hypercholesterolemia.

BACKGROUND: Previous studies have suggested that statins exert beneficial effects beyond their favorable lipid lowering effect. Particularly, the modification of thrombus formation and degradation, alteration in inflammatory response, plaque stabilization and improved endothelial function are thought to be responsible for additional reduction of morbidity and mortality due to cardiovascular events. To date, however, it is still unclear whether these effects are elicited by all statins. METHODS AND RESULTS: We set out to compare in a controlled, randomized, double-blind study design the effects of almost equieffective cholesterol lowering doses of three chemically and pharmacokinetically different statins (atorvastatin, simvastatin, pravastatin) on hemostatic and inflammatory markers in 99 hypercholesterolemic patients. At entry and 3 months after onset of statin therapy plasma cholesterol and von Willebrand factor antigen (vWf-Ag), fibrinogen, d-dimer, prothrombin fragment 1+2 (F1.2) and C-reactive protein (CRP) were measured. The effect on plasma values of F1.2, vWf-Ag, d-dimer and CRP was not significantly different between the three treatment groups. The effect of simvastatin on fibrinogen (p = 0.005) was more pronounced than the effects of atorvastatin (p = 0.48 n.s.) and pravastatin (p = 0.15 n.s.). Plasma levels of F1.2 and vWf-Ag (when data of all statins were pooled) were significantly reduced by 7% and 10% versus baseline, respectively. No significant reduction was observed for d-dimer (p = 0.26) and CRP (p = 0.5). Total plasma cholesterol levels decreased significantly (p < 0.0001 in all groups) between 22% and 29% compared to baseline. CONCLUSION: The present study shows similar short-term (3 months) effects of atorvastatin, simvastatin and pravastatin on selected hemostatic and inflammatory parameters in plasma in patients with hypercholesterolemia. Thus, chemical and pharmacological differences between statins appear to exert no major influence on these parameters.

Management of serious staphylococcal infections in the outpatient setting.

Patients with serious staphylococcal infections, e.g. endocarditis and osteomyelitis, need prompt and prolonged parenteral antibiotic treatment to ensure eradication of the causative pathogen. The major cost in the treatment of these infections is the long period of hospitalisation required for the administration of intravenous antibiotics. To shorten the hospitalisation period, outpatient treatment can be given to some patients. In this study, patients with acute exacerbations of chronic osteomyelitis (n = 44) or endocarditis (n = 10) were treated with intravenous teicoplanin. The pathogens were Staphylococcus aureus (n = 41, 13 of which were methicillin resistant) and coagulase-negative staphylococci (n = 13, one of which was methicillin resistant). After a mean loading dose of 15 mg/kg for 3 to 10 days, patients received teicoplanin 3 times a week at a dose (mean 15 mg/kg) individualised to achieve serum trough concentrations of approximately 10 mg/L for osteomyelitis and 20 mg/L for endocarditis. Treatment duration ranged from 28 to 150 (mean 62) days for patients with osteomyelitis and from 28 to 88 (mean 49) days for patients with endocarditis. 37 (84%) patients with osteomyelitis and 8 (80%) patients with endocarditis were treated successfully. Adverse events were observed in 9 patients and included rash (n = 3), thrombocytopenia (n = 3), and drug fever, pseudomembranous colitis, nausea, leucopenia and transient hearing impairment (one patient each). In conclusion, this study demonstrates that teicoplanin can be administered successfully in an outpatient setting according to a 3-times weekly schedule for the treatment of patients with staphylococcal osteomyelitis and endocarditis.

The protein C system in patients undergoing cardiopulmonary bypass.

Fifteen men undergoing extracorporeal circulation for aorta-coronary bypass grafting were investigated for alterations of the plasma levels of cross-linked fibrin degradation products, protein C, free protein S, coagulation factor II, immunoglobulin G, and albumin. Although all patients were given heparin, a progressive increase of cross-linked fibrin degradation products was recorded during extracorporeal circulation, which indicates an activation of the plasmatic coagulation system. This increase was most pronounced in the late phase of extracorporeal circulation after reperfusion of the lung and in the early postoperative period. The levels of all other investigated plasma proteins decreased drastically after the patient was connected to the bypass circuit, which was primed with saline solution. These levels increased after termination of extracorporeal circulation and administration of fresh-frozen plasma. To study the consumption of protein C, protein S, and factor II during extracorporeal circulation, we formed ratios of the values of these parameters to the value of immunoglobulin G. After this volume correction, protein C was found to decrease significantly in the late phase of extracorporeal circulation, remaining low in the early postoperative period; protein S increased significantly soon after the onset of extracorporeal circulation and decreased after termination of extracorporeal circulation; factor II was unaffected by extracorporeal circulation, showing only a slight, insignificant increase in the postoperative phase. These results suggest a disturbance of the protein C system by extracorporeal circulation, which is possibly linked to the reported high bleeding tendency in patients undergoing operations with extracorporeal circulation.

Effect of intraoperative aprotinin administration on postoperative bleeding in patients undergoing cardiopulmonary bypass operation.

To study the hemostyptic effect of aprotinin (Trasylol) in patients undergoing extracorporeal circulation for coronary artery bypass operations, we randomized 12 of 24 patients to receive aprotinin in high dosage (about 800 mg) during extracorporeal circulation. From the resulting two groups each, one patient was excluded from the study because of postoperative myocardial infarction (control group) and surgical hemorrhage (aprotinin group) leading to a second operation. Although heparin was used for anticoagulation in all 22 patients, all had a marked increase in plasma levels of thrombin-antithrombin III complexes during extracorporeal circulation, indicating an intravasal activation of coagulation. By monitoring the plasma levels of fibrin degradation products in patients without aprotinin therapy, we recorded a concomitant hyperfibrinolysis significantly less pronounced in patients receiving aprotinin (p less than 0.005). The mean total postoperative blood loss was lower in patients receiving aprotinin (620 ml) than in control patients (1000 ml; p less than 0.03). The results confirm previous reports of a hemostyptic effect of aprotinin in cardiac operations. This effect is probably due to a prevention of hyperfibrinolysis.

Aprotinin increases release of von Willebrand factor in cultured human umbilical vein endothelial cells.

Through the perioperative administration of the proteinase inhibitor aprotinin, hemostasis can be improved and postoperative bleeding reduced after cardiac operations. The mechanism of action has been only partially clarified. The goal of our study was to investigate the influence of aprotinin on the synthesis of von Willebrand factor (vWF) in human endothelial cells. Human umbilical vein endothelial cells (HUVEC) were cultivated in vitro and incubated with different aprotinin concentrations (55, 100, and 215 mol/L). With all investigated aprotinin concentrations, there was an increase in vWF synthesis compared with basal secretion (p less than 0.001). When the HUVEC were preincubated with aprotinin and stimulated with thrombin, there was a further significant increase in vWF synthesis. HUVEC that, were first incubated with aprotinin and then stimulated with thrombin demonstrated a significant increase in vWF synthesis compared with basal secretion in nonincubated cells (p less than 0.0001). Also, compared with the cells that had received thrombin stimulation alone, the combination of aprotinin incubation and thrombin stimulation led to a significantly higher vWF concentration (p less than 0.05). Because vWF is necessary for the interaction with platelet factor glycoprotein Ib and platelet adhesion, the demonstrated increase in vWF synthesis could be one of the mechanisms of action of aprotinin leading to its blood-sparing effect.

Heterogeneity of human factor VIII/vWF in lipaemic plasma.

In order to determine the influence of plasma lipids on the apparent molecular size of human F VIII/vWF and on the relationship of the factor-related properties, namely F VIII:C, F VIIIR:Rcof, and F VIIIR:Ag to F VIII/vWF, the factor's elution pattern in the presence of lipids on Sephacryl 1000 was investigated. When fresh plasma of fasting donors was chromatographed on this gel, F VIII/vWF eluted in a single sharp peak with all three F VIII-related activities appearing in the separation range of the gel column. When fresh postprandial lipaemic plasma was chromatographed on this gel, F VIII/vWF showed distinct heterogeneity in the elution pattern with respect to molecular size and relationship to the F VIII-related properties. After incubation of lipaemic plasma with phospholipase C the elution pattern of F VIII/vWF changed from heterogeneity to homogeneity similar to those of plasma of fasting donors. After incubation of lipaemic plasma with triglycerid lipase the elution pattern of F VIII/vWF remained heterogenous. A similar heterogeneity in the elution pattern of F VIII/vWF was found when plasma of fasting donors was mixed with a preparation of very low density lipoproteins derived from human postprandial plasma or with a preparation of coagulant-active phospholipids.

Hemostasis activation in patients with liver cirrhosis.

In patients with liver cirrhosis a decrease of the coagulant potential is well-documented and has been linked to the high bleeding tendency among these patients. Whether the decrease of the coagulant potential is only due to a reduced hepatic synthesis of coagulation factors or also to its consumption by disseminated intravascular coagulation is debatable. We investigated hemostasis activation markers thrombin-antithrombin III complexes (TAT), fibrin degradation products (D-Dimer) and plasmin-alpha 2-antiplasmin complexes (PAP) in 41 outpatients with liver cirrhosis (Child-Pugh index 1 n = 18, 2 n = 15, 3 n = 8). Compared to controls similar in terms of age and sex, TAT, D-Dimer and PAP was elevated in the whole group of patients. A progressive increase of D-Dimer and PAP from Child 1 to 3 indicates a relationship between the severity of cirrhosis and the amount of hemostasis activation. Investigation of the natural anticoagulant potential showed significant decreases of antithrombin III (AT III), protein C, and protein S, most pronounced in Child 3 patients. Statistical analysis revealed significant negative correlations between levels of D-Dimer and both AT III and protein C, indicating that hemostasis activation is linked to the loss of anticoagulant potential.

Comparison of four rapid D-Dimer tests for diagnosis of pulmonary embolism.

Aim of this study was to evaluate rapid D-Dimer tests for their utility in diagnosis of acute pulmonary embolism (PE). Tests were performed in 183 consecutive pats referred for lung scanning because of clinically suspected PE. According to lung scans and the clinical course of disease 19 pats were classified to have PE with high probability and 164 with low probability. An ELISA (Agen) was used as the D-Dimer reference, and results compared with those of a turbidimetric (Behring), an immunofiltration (Nycomed), latex plasma and whole blood agglutination test (both Agen). There was a poor correlation between the turbidimetric test and either the ELISA (R = 0.38) and immunofiltration test (R = 0.49). The correlation between the ELISA and immunofiltration test was better (R = 0.73). The qualitative latex and whole blood agglutination tests were better fitted to ELISA since positive and negative samples were overlapped only in their 1st and 9th percentiles of ELISA values. The whole blood agglutination test was positive at lower ELISA values than the latex test. The highest sensitivity test for PE was the immunofiltration test (95%) (500ng/mL cut-off), followed by the turbidimetric method (89%) (66ng/mL), the ELISA (89%) (300ng/mL), the whole blood test (88%) and the latex test (68%). Specificity was lowest for the immunofiltration test (33%), intermediate (57-65%) for the turbidimetric and whole blood agglutination tests, and highest for the ELISA and the most insensitive latex test (76/77%). The whole blood assay was found to be the fastest and most suitable for bed site testing but weak positives were difficult to read. The immunofiltration test required plasma preparation but allowed objective semiquantitation of results. The less rapid turbidimetric assay was fully quantitative and objective.

Quantitative determination of human protein C. Evaluation of a "fast" functional assay in comparison to a "traditional" functional and an immunological assay.

A fast functional assay for protein C was evaluated and compared with a traditional functional and an enzyme linked immunosorbent assay in parallel for the same plasma samples derived from 43 healthy subjects, 12 patients with severe hepatic dysfunction, and 23 patients under stable oral anticoagulation. By all three test systems significantly lower levels of protein C were obtained in both groups of patients compared with normal subjects (p less than 0.0001). No significant between - assay differences were found in normal subjects and in patients with hepatic dysfunction; by correlation analysis coefficients higher than 0.8 were calculated between the measurements of the three tests. In patients under stable oral anticoagulation, however, the immunologic test yielded higher values than the traditional (p less than 0.05) and, more pronounced, the fast functional assay (p less than 0.0001); no or only borderline significant correlations between the results were found. In these patients protein C levels measured with the traditional functional assay were in the same range as the activity levels of factors II, VII, IX, and X, whereas the fast functional test yielded significantly lower levels. The presented results indicate that very similar protein C levels were obtained with both functional and the immunologic assay except in patients under oral anticoagulation.

Laboratory monitoring of thromboprophylaxis with low molecular weight and standard heparin.

This study was made to evaluate assays for monitoring of low dose heparin thromboprophylaxis and to evaluate its efficacy in reduction of hypercoagulation. Patients with medical diseases scheduled for routine thromboprophylaxis were subcutaneously treated with either 5.000 anti XaU low molecular weight (LMW) heparin once daily (n = 20) or 5.000 IU standard (ST) heparin 3 times daily (n = 19). On days 1,2,3, before, 1 and 4 hours after heparin injection APTT, TCT, anti Xa, Heptest, thrombin-antithrombin complexes (TAT), and D-Dimer levels were measured. In the LMW heparin group, median values of APTT and TCT slightly increased after heparin and the ranges of pre- and postinjection values showed extensive overlap. However, values of anti Xa and Heptest markedly increased, showing complete separation of ranges. In the ST heparin group neither APTT, TCT, anti Xa, nor Heptest were significantly different comparing pre- and postheparin values. Half of the patients in both groups had subclinical hypercoagulation at baseline (TAT greater than 5 ng/ml, D-Dimer greater than 200 ng/ml). On day 3 of prophylaxis this percentage was not significantly decreased. Moreover, several patients in both groups increased in TAT and D-Dimer. In the LMWheparin group, negative correlations between body weight and 4 h postinjection heparin levels were found (anti Xa R = -0.50, Heptest R = -0.31) and between 1 h postinjection heparin and TAT and D-Dimer levels 3 h later (TAT-anti Xa R = -0.58, TAT-Heptest R = -0.64, D-Dimer-anti Xa R = -0.32, D-Dimer-Heptest R = -0.33).(ABSTRACT TRUNCATED AT 250 WORDS)