Anticardiolipin antibodies are not associated with restenosis or endothelial activation after percutaneous transluminal angioplasty

OBJECTIVE

Restenosis following percutaneous transluminal angioplasty (PTA) continues to be a major clinical problem. Anticardiolipin antibodies (aCL) have been established as risk factors for venous or arterial thrombosis. The aim of this study was to assess: a) the influence of positive aCL upon restenosis within 6 months after PTA, b) the possibility of a seroconversion from negative to positive aCL after PTA and c) a possible link between positive aCL and endothelial activation.

EXPERIMENTAL DESIGN

71 patients (50 men and 21 women, age 68+/-13 years) with peripheral arterial occlusive disease (PAOD, Fontaine II-IV) undergoing a successful PTA entered the study and were prospectively followed for 3 and 6 months thereafter.

INTERVENTIONS

PTA was carried out successfully and noninvasive grading was done with duplex scanning. Laboratory investigation included aCL, thrombin generation markers, such as thrombin-antithrombin III complexes and prothrombin fragments 1+2, as well as thrombomodulin, soluble P-selectin, E-selectin and the vascular cell adhesion molecule-1, as endothelial activation markers.

RESULTS

30/71 (42.3%) patients developed restenosis (>50% reduction of the lumen diameter) within 6 months after PTA. 9/71(12.7%), had positive aCL IgG (19-35 GPL) and/or IgM (14-103 MPL) at all three measurements. 2/9 (22.2%) of aCL positive and 28/62 (45.2%) of aCL negative patients had restenosis at 6 months after PTA (relative risk RR=0.51, 95%-Cl: 0.14-1.78, chi2 non-significant). All other parameters did not differ between aCL positive and -negative groups.

CONCLUSIONS

Our findings suggest that: a) patients with PAOD have a slightly higher prevalence of positive aCL compared to the general population, but no association is evident between positive aCL and restenosis within 6 months after PTA, b) no seroconversion from negative to positive aCL occurred within 6 months after PTA, c) no association of aCL with endothelial activation markers or thrombin generation markers was found.

Acute von Willebrand factor secretion from the endothelium in vivo: assessment through plasma propeptide (vWf:AgII) Levels

Elevated plasma concentrations of von Willebrand factor (vWf) are increasingly recognized as a cardiovascular risk factor, and are used as a marker of endothelial activation. However, the factors which determine the rate of vWf release from the endothelium in vivo have not been defined clearly. In addition, vWf plasma levels may also be influenced by adhesion of vWf to the vascular wall or to platelets, and by its rate of degradation. The propeptide of vWf (also called vWf:AgII) is stored and released in equimolar amounts with vWf. In the present study we attempted to determine whether this propeptide could be a more reliable marker of endothelial secretion than vWf itself. To accomplish this we developed an ELISA based on monoclonal antibodies. The propeptide levels in normal plasma were found to be 0.7 microgram/ml, more than 10 times lower than vWf itself. Administration of desmopressin (DDAVP) induced a rapid relative increase in propeptide (from 106 to 879%) and in vWf (from 112 to 272%). However, the increases in vWf and propeptide were equivalent when expressed in molar units. A time course study indicated a half-life of the propeptide of 3 h or less. In a baboon model of disseminated intravascular coagulation (DIC) induced by FXa, vWf increased by less than 100%, whereas the propeptide concentrations increased by up to 450%. In view of the massive thrombin generation (as assessed by fibrinogen depletion), the increases in vWf are small, compared to the strong secretory response to thrombin and fibrin previously observed in vitro. Our results suggest that due to its rapid turnover, the propeptide could provide a sensitive plasma marker of acute endothelial secretion.

Procoagulant activity of purified protein derivative-stimulated pleural effusion mononuclear cells in tuberculous pleurisy

Mononuclear cells (MNC) generate cell-bound procoagulant activity (PCA) which shortens recalcification time after incubation with an antigen to which the donor has been sensitized. PCA has been demonstrated in various lung diseases, including exudative pleural effusions. To determine the value of measuring cell-bound PCA in the diagnosis of tuberculous pleural effusions we examined pleural effusion MNC of patients with tuberculosis (n = 19), congestive heart failure (n = 7), and carcinoma (n = 7). MNC were isolated, incubated in 0 or 10 micrograms/ml purified protein derivative (PPD) for 15 min and for 20 h, and recalcification time determined. Incubation with thromboplastin was used as control. The recalcification times in serum incubated for 15 min varied within a wide range, the mean values were longest for tuberculous effusion MNC, incubation for 20 h increased variation. Incubation of cells for 15 min with thromboplastin led to a decrease of mean recalcification time in tuberculous (p < 0.001) and heart failure (p < 0.05), and with no significance in carcinomatous effusions. Incubation with PPD led to decrease of recalcification time which was not significant. Comparisons of the mean relative recalcification times after PPD incubation showed that tuberculosis differed from lung cancer (p < 0.001), lung cancer from heart failure (p < 0.05), but not heart failure from tuberculosis. We conclude from our study that pleural effusion MNC express spontaneous PCA in vitro which is strongest in carcinomatous pleural effusions. Incubation of MNC with thromboplastin and less discernable with PPD leads to an increase in PCA which is more pronounced in tuberculous pleural effusions. However, due to substantial intersubject variability and overlap between the study groups, this test does not allow reliable differentiation of tuberculous from other MNC rich pleural effusions.

[Bernard-Soulier thrombocytopenia: clinical significance of a rare disorder]

We present 5 cases with thrombocytopenia and abnormal platelet function. The diagnosis of Bernard-Soulier syndrome was suspected in some subjects of advanced age on the ground of morphologic changes in the thrombocytes and of low platelet counts with or without prolonged bleeding time. The platelets showed normal aggregation with adrenalin, ADP and collagen but abnormal agglutination with ristocetine. All patients had normal von Willebrand factor levels in plasma. Flow cytometry demonstrated on thrombocytes lack of GP Ib expression of varying degree in comparison to normal controls, using various anti-GP Ib-antibodies (CD42b). The combination of these findings confirmed the diagnosis of Bernard-Soulier syndrome with varying expression of GP Ib. Flow cytometry and the use of specific monoclonal antibodies may be a rapid and reliable diagnostic tool. Differential diagnosis and treatment strategies are discussed. A congenital thrombopathy should always be considered in patients with thrombocytopenia of unknown origin and abnormal platelet morphology.

Anticardiolipin antibodies do not seem to be associated with APC resistance in vivo or in vitro

Anticardiolipin antibodies (aCL) or lupus anticoagulants (LA) have been found to exert an inhibitory action upon the activation and function of protein C, a natural coagulation inhibitor. Recently an in vitro phenomenon called resistance to activated protein C (APC resistance) has been described as the most frequent cause of hereditary thrombophilia. In order to see whether a positive association of APC resistance with aCL exists we examined plasma of 162 consecutive outpatients referred for thrombophilia screening. Further, the IgG fraction was isolated from plasma of two aCL-positive and LA-negative patients and of two aCL-negative healthy subjects by means of protein A affinity chromatography. Each of these isolates was mixed with normal plasma, and the APC resistance was assayed; 25/162 (15.4%) patients had confirmed abnormal APC resistance. Only 1/25 (4.0%) APC resistance-positive patients and 11/137 (8.0%) APC resistance-negative patients had positive IgG- and/or IgM-aCL (p = 0.5, nonsignificant). In the in vitro test system the APC resistance ratio remained unaffected after addition of normal IgG or aCL-IgG fraction in the tested normal plasma and did not deviate from the range of buffer controls. These data do not suggest any association of aCL with abnormal APC resistance. aCL-IgG fractions from aCL-positive and LA-negative plasmas do not interfere with the APC resistance test system in vitro in low concentration.

[Lipoprotein(a) and hemostasis activation markers in angina pectoris]

STATEMENT OF PROBLEM

To analyse whether lipoprotein(a) is a risk factor for myocardial infarction, stroke and acute peripheral arterial occlusion in coronary heart disease and whether this risk can be assessed by clotting activation markers.

PATIENTS AND METHODS

A partly prospective, partly retrospective study of data on 237 consecutive patients (201 men, 36 women; mean age 55 [24-76] years) who had undergone coronary arteriography because of severe angina. Concentrations were measured for: beta-thromboglobulin, platelet factor 4, fibrinopeptide A, D-dimers, thrombin-antithrombin III factor (TAT), prothrombin fragments 1 + 2, lipoprotein(a), apolipoprotein A-I (apoA-I), cholesterol and triglycerides. Analysis of any relationship between the findings on coronary arteriography (degree of stenosis) and the occurrence of myocardial infarction, stroke and acute peripheral arterial occlusion before and during the 2 years after the arteriography.

RESULTS

There was no correlation between lipid parameters and clotting or platelet activation markers. Patients with a history of acute peripheral arterial occlusion had raised values for lipoprotein(a) and TAT. In the prospective part of the study (i.e. during the first 2 years after blood samples had been taken), there was no correlation.

CONCLUSIONS

In patients with coronary artery disease and angina pectoris no correlation was found between lipoprotein(a) and haemostasis activation markers. None of these parameters--prospectively evaluated--could predict risk of thromboembolism.

Intramedullary nailing and pulmonary embolism: does unreamed nailing prevent embolization? An in vivo study in rabbits

Pulmonary embolism in reamed femoral nailing has been reported and discussed over recent years. Does an unreamed nailing technique with a solid nail prevent this rare but serious complication of intramedullary fixation? In an animal model in rabbits, we studied the pathophysiologic impact on pulmonary function and the impact on hemostasis of reamed and unreamed nailing of intact femora and tibiae, and of femoral fracture in relation to intramedullary pressure. No statistical difference of PaO2, PaCO2, and PCO2et was found in the femur whether a reamed or unreamed procedure was performed. Two of six animals with unreamed femoral nailing, one of six animal with reamed femoral nailing, and one of five animals with a femoral fracture fulfilled four of four or three of four criteria for embolization (increase of the difference of PaCO2 and PCO2et, decrease of PaO2, increase of blast cells in central-venous blood and bone marrow/fat in histologic section of the lungs and bone). Tibial nailing did not alter pulmonary function in either group. Intramedullary pressure was increased in all animals with perioperative impairment of pulmonary function (375 to 676 mbar). Analysis of the hemostatic results showed a significant difference of platelet activation in reamed versus unreamed nailing of the femur 1 hour after nailing (p < 0.01) and a significant decrease of fibrinogen and antithrombin III (p < 0.001/p < 0.01) in reamed femoral nailing. We conclude that unreamed nailing of the femur with a solid rod may also cause bone marrow embolization with alteration of pulmonary function as long as an important increase of the intramedullary pressure is generated during the nailing procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

[Activation of endothelium-dependent hemostatic factors following bone marrow transplantation]

Changes in hemostatic factors after bone marrow transplantation (BMT), with or without thrombotic complications, have already been described. The endothelium seems to be actively involved in such processes. Over a period of 2 years we evaluated various hemostatic factors, associated or not with endothelial stimulation, in 44 patients with BMT (40 leukemias and 4 aplastic anemias). Factor VIII activity (VIII:C), von Willebrand factor antigen (vWF:Ag), tissue plasminogen activator antigen (tPA), plasminogen activator inhibitor activity (PAI-1), antithrombin III, protein C and protein S were assayed before and 1, 3, 6, 12, 18, and 24 months after BMT. Factor VIII:C, vWF and tPA were found to be significantly increased 1-6 months after BMT, returning to normal later. Patients with acute graft versus host disease, fever or cyclosporin treatment had significantly higher VIII:C, vWF and tPA. The increase in these factors implies lasting stimulation of their release and/or synthesis from endothelial cells that is enhanced by some complications of BMT. The degree and character of these changes could favor activation of thrombotic processes.

Delayed hypersensitivity to one low-molecular-weight heparin with tolerance of other low-molecular-weight heparins

We report a patient who developed infiltrated plaques at the sites of subcutaneous injection of a low-molecular-weight heparin. Skin tests and a lymphocyte transformation test revealed hypersensitivity to sandoparin and heparin sodium. The low-molecular-weight heparins nadroparin and dalteparin were subsequently tolerated without adverse effects. Possible risk factors for sensitization are discussed.

Procoagulant activity of PPD-stimulated human lymphocytes after cryopreservation

OBJECTIVE

Human mononuclear cells from a previously sensitized donor generate procoagulant activity (PCA) following stimulation with purified protein derivative (PPD). Lymphocytes of tuberculous pleural effusions are also highly responsive to PPD stimulation. We examined the influence of cryopreservation on lymphocytes following stimulation with PPD.

DESIGN

Peripheral blood lymphocytes of 5 healthy PPD skin test positive subjects were incubated with either PPD, thromboplastin, or concanavalin A (Con A) at concentrations of 0, 1, and 10 micrograms/ml. PCA was determined by measuring the recalcification time. Tests were repeated following cryopreservation for 4 weeks.

RESULTS

Incubation of fresh lymphocytes led to a dose dependent shortening of recalcification time: PPD (0-1-10 micrograms/ml: 100-84-65%), thromboplastin (0-1-10 micrograms/ml: 100-85-62%), and Con A (0-1-10 micrograms/ml: 100-85-42%). These results were highly reproducible when tests were repeated 6 weeks later. Cryopreservation did not significantly affect the expression of PCA following incubation with PPD and with thromboplastin. In contrast, cryopreservation significantly diminished the degree of Con A generated PCA.

CONCLUSION

Cryopreservation and storage of human lymphocytes is possible without alteration of PCA expression following their incubation with PPD or thromboplastin.

[Antiphospholipid syndrome: a new clinical entity? Part 2: pathophysiological aspects and treatment possibilities]

Antiphospholipid antibodies are immunoglobulins of the IgG, IgM or rarely IgA class directed against phospholipids or phospholipid-protein complexes of the coagulation cascade. They were first described in patients with systemic lupus erythematosus, but are also frequent in other autoimmune diseases, lymphoproliferative and malignant disorders, some bacterial and viral infections, and after drug exposure. Their mechanism of action is considered multiple, disturbing various natural inhibitory pathways of coagulation. Clinically they have been associated with a thrombotic tendency without a proven direct causal role. Both arterial and venous thromboses, as well as habitual abortion in pregnant women, are reported. A variety of treatment measures have been tried against these associated clinical manifestations.

[Antiphospholipid syndrome: a new clinical entity? Part 1: antiphospholipid antibodies: specificity and methodological problems]

A new clinical entity, the antiphospholipid syndrome, has recently been described. It is based on the detection of antiphospholipid antibodies either by coagulation tests or by ELISA assay. The precise epitopes towards which these antibodies are directed is a matter of controversy. It is even possible that the name antiphospholipid is inappropriate. The diagnosis of lupus like anticoagulant (LA) detected by coagulation tests requires a three step procedure after appropriate processing of plasma samples. Antiphospholipid antibodies can also be identified by ELISA; this assay is simpler, but there is still a need for standardization. LA and antiphospholipid antibodies identified by ELISA are similar, but not identical; they have similar clinical implications. Due to the heterogeneity of the antibodies and the antigens it is necessary to use a panel of tests to establish or exclude the presence of antiphospholipid antibodies. In the future a better knowledge of antibodies' specificity should help in selecting the most useful test for clinical purposes.

[Local therapeutic fibrinolysis in ischemic cerebrovascular insults: initial findings in 6 patients]

Local therapeutic fibrinolysis is considered an efficient and established treatment for peripheral arterial occlusive disease. The introduction of newer fibrinolytics along with the development of interventional catheterization techniques have extended its use to previously untreated events such as cerebrovascular occlusions. Between 1989-1991 six patients with basilar and/or middle cerebral artery thrombosis were treated at the University Hospital, Basel, by superselective local intraarterial infusion of 400,000 U/h urokinase for 1-2 hours. Two of four patients with basilar artery occlusion showed complete remission one year after the intervention. The third showed no neurological improvement despite angiographic recanalization, and 48 h later suffered a fatal brainstem haemorrhage, while the fourth did not recover from coma and succumbed. Both patients with occlusion of the middle cerebral artery showed complete recanalization, but one had complete and the other partial neurological remission. Signs of slight systemic fibrinolysis were present but never attained the intensity of systemic therapeutic fibrinolysis as the antiplasmin and fibrinogen values showed. In summary, local therapeutic fibrinolysis contributes to the reduction of mortality and to remission of symptoms in occlusions of basilar artery, and offers some advantage in occlusions of the middle cerebral artery. A definite benefit from the latter will be proved only through large-scale randomized trials. The indication for local therapeutic fibrinolysis for thromboses of cerebral arteries requires a careful benefit-risk evaluation, an experienced angiography team and a special infrastructure for computed tomography and digital subtraction angiography.

Clinical pharmacology of intravenously administered recombinant desulfatohirudin (CGP 39393) in healthy volunteers

Clinical pharmacology of the intravenously administered recombinant desulfatohirudin CGP 39393 was investigated in 47 healthy volunteers in a multicenter study. Mean peak concentrations after bolus injections of 0.1, 0.3, 0.5, and 1.0 mg/kg were 154, 443, 764, and 1,691 nmol/L, respectively. Intravenous infusions of 0.1 mg/kg/h for 6 h and of 0.2 and 0.3 mg/kg/h for 6 h and 72 h resulted in mean steady-state levels of 78, 227, and 312 nmol/L. Elimination was multiexponential and dose independent. Concordant pharmacokinetic parameters were obtained from both i.v. bolus and infusion experiments (overall average total plasma clearance, 2.20 ml/min/kg; mean residence time, 2.12 h; volume at steady state, 0.27 L/kg). Thrombin inhibition by CGP 39393 was demonstrated ex vivo by the thrombin chromogenic assay (TCA), by activated partial thromboplastin time (APTT), thrombin time (TT), and prothrombin time (PT). Following a parabolic function APTT doubled and quadrupled at CGP 39393 concentrations of 100 and 1,000 nmol/L, respectively. Whereas TTs (bovine thrombin 3 or 6 IU/ml) were very sensitive to low CGP 39393 levels with unmeasurable clotting times at CGP 39393 concentrations greater than 30 and 60 nmol/L, PT was prolonged by a factor of only 1.3 above baseline at 300 nmol/L. APTT appears to be most suitable for monitoring the anticoagulant effect of CGP 39393 over a broad concentration range. The drug was well tolerated without clinically relevant bleeding episodes or other adverse events.

Autoantibodies against the platelet glycoproteins (GP) IIb/IIIa, Ia/IIa, and IV and partial deficiency in GPIV in a patient with a bleeding disorder and a defective platelet collagen interaction

To evaluate the physiologic importance of the different collagen receptors on platelets, we screened 806 patients admitted to the hospital because of hemorrhagic diathesis for eventual laboratory evidence of a pathologic platelet collagen interaction, and found 5 patients with an isolated deficiency in collagen-induced platelet aggregation. Four of these five patients had a partial defect, one had a complete defect. The structural and functional analysis of the platelets from the patient with a complete defect showed a deficiency in glycoprotein (GP) IV and autoantibodies against GPIIb/IIIa, GPIa/IIa, and GPIV. Patient plasma had only a minimal effect on normal control platelets and Naka-negative platelets. The analyses of the defect in the patient and of the data in the literature suggest that a single defect may not result in clinical bleeding (GPIV-deficient patients do not bleed), but may become symptomatic in combination with another defect such as the autoantibodies against GPIa/IIa, GPIV, and/or GPIIb/IIIa, all of which are involved in platelet collagen interactions (three of four of our immune thrombocytopenic purpura patients with anti-GPIV and anti-GPIIb/IIIa autoantibodies had a bleeding disorder). We hypothesize that it is the synergism of two abnormalities that results in the defective function, a mechanism that is in agreement with earlier studies on platelet collagen interaction that suggests that a double defect in platelet collagen interactions is required to become clinically apparent.

Lack of association between antiphospholipid antibodies and migraine

We prospectively studied the prevalence of lupus anticoagulant, anticardiolipin antibodies (aCL) and various haemostatic parameters in 71 patients with migraine and compared the results with a control group of 32 subjects with back pain never having experienced migraine. The patients with migraine were divided into two groups: group I with migraine without (n = 18) and with aura lasting less than 60 min (n = 24) and group II with migraine with prolonged aura or migrainous infarction (complicated migraine, n = 29). The following results were obtained: a) no difference in aCL positivity was noted between migrainous patients and controls and between common migraine and complicated migraine patients and b) no statistically significant difference in haemostatic parameters (except for thrombin-antithrombin III complexes) was found between the two groups of migraine and between aCL positive and negative migrainous patients. These data suggest that anticardiolipin antibodies are not involved in the pathogenesis of migraine complications.

[Internal medicine therapy of venous thromboembolism]

Treatment of venous thromboembolism aims at the reduction of mortality of massive pulmonary embolism, the arrest of further thrombotic processes and at avoiding late post-thrombotic sequelae. Anticoagulation with heparin and oral anticoagulants remains the treatment of choice. Heparin is administered intravenously or subcutaneously for four to five days. Oral anticoagulation follows thereafter for three to six months or even life-long. Low molecular weight heparin will probably be able to substitute for the unfractionated heparin in the initial treatment phase. Therapeutic fibrinolysis or surgical treatment are considered as alternative treatment modalities. Furthermore, new potent thrombin or platelet inhibitors appear as promising future antithrombotics.

Anticardiolipin antibodies and coronary heart disease

Arterial or venous thrombotic events have been described as complications in patients with positive anticardiolipin antibodies (aCL), affecting various organs including the heart. In order to see whether aCL could be, among others, a predisposing factor for coronary artery occlusions and whether it could serve as a prognostic marker for coronary heart disease, 232 patients enrolled in the European Concerted Action on Thrombosis Angina Pectoris Study were studied. aCL and various other haemostatic parameters were determined at time of admittance in order to see whether a relationship existed between haemostasis at baseline and extent or prognosis of the cardiovascular disease. A follow-up at 12 and 24 months after angiography included information about relapsing coronary or other thrombotic events, treatment and outcome of the disease. aCL were not found to be a marker of either progressive cardiovascular disease or recurrent thrombotic events. No correlation was found, either in aCL positive or in aCL negative patients, between high levels of haemostasis activation markers, such as beta-thromboglobulin, platelet factor 4 or fibrinopeptide A and recurrent cardiovascular disease.

Lupus anticoagulants/anticardiolipin antibodies in patients with normal tension glaucoma

Ocular vascular occlusive disease resulting in severe retinopathy and/or post-thrombotic glaucoma has been extensively discussed in patients with lupus anticoagulant and/or anticardiolipin antibodies (LA/aCL). Inadequate circulation plays an important role in the pathogenesis of another ophthalmic entity--the normal tension glaucoma. We studied 22 patients with normal tension glaucoma (group I) and 23 with chronic open-angle glaucoma (group II) and compared them with a control group (n = 25, group III). LA, aCL, the aCL cofactor beta 2-Glycoprotein I, and other haemostatic parameters including factor VIII:C, von Willebrand factor, factors II, V, VII and plasminogen activator inhibitor were measured. Five out of 22 (22.7%) in group I, five out of 23 (21.7%) in group II and three out of 25 (12.0%) in group III had positive LA and/or aCL. These prevalences were not statistically significantly different. beta 2-Glycoprotein I was normal in all groups. No other parameters were significantly different between groups. These findings do not support the contribution of ocular microvascular occlusive disease, due to elevated aCL, in the pathogenesis of glaucomatous damage.

[Profibrinolytic activity of recombinant hirudin?]

Recombinant hirudin (rH, CGP 39393) is a potent thrombin inhibitor. In addition to its anticoagulant effect, we investigated its profibrinolytic activity in vitro and ex vivo. The fibrinolytic activity of the euglobulin fraction of 15 normal plasmas with or without urokinase was tested in a fibrin plate assay both before and after addition of rH. The same cycle was repeated in 8 plasmas with heparin instead of rH. For the ex vivo evaluation 12 healthy volunteers received 0.1-0.3 mg/kg/h rH for 6 h. Blood samples were drawn at 0 h, 6 h, 12 h and 24 h and various fibrinolytic parameters were assayed. In the presence of rH or heparin a slightly stronger fibrinolytic effect was observed, measured as fibrin plate lysis activity, both when rH was added to plasma in vitro and when it was administered intravenously. However, this may be explained by the specific anticoagulant action of rH and heparin in the dynamic equilibrium of fibrinolysis and clotting in the test system. Moreover, under rH treatment the observed changes in the various fibrinolytic parameters could not be differentiated from the normal circadian rhythm of these proteins. There was no convincing evidence to indicate enhancement of plasma fibrinolytic activity by recombinant hirudin.

[Tendency to thrombosis following bone marrow transplantation?]

Various thrombosis related parameters of the hemostatic system were evaluated in 11 patients who had had bone marrow transplantation (BMT). At 0, 1, 3 and 6 months after BMT, antithrombin III, heparin cofactor II, protein S (PS), factor VIII:C, von Willebrand factor (vWF:Ag, vWF:RiCof), tissue plasminogen activator (tPA), plasminogen activator inhibitor, thrombin antithrombin III complexes (TAT), d-dimers (DD) and antiphospholipid antibodies (APA) were determined. A statistically significant rise in the levels of vWF was observed after BMT, with a similar trend for tPA. High TAT and/or DD were detected in 10/11 patients and positive APA only in 5/11. Of the other parameters only free PS was permanently low, with normal total PS and C4bBP. These findings suggest persistent thrombin generation peri- and post-BMT. The significantly high vWF and the low free PS could foster a procoagulant state.

Lupus anticoagulant--antiphospholipid antibodies and thrombophilia. Relation to protein C--protein S--thrombomodulin

In order to define the behavior of the lupus anticoagulant and/or antiphospholipid antibodies, we investigated the possible association with protein C, protein S and thrombomodulin. In 19 patients with established diagnosis of an autoimmune disease and coexisting lupus anticoagulant protein C (antigen and activity), protein S (total and free), anticardiolipin and antiphosphatidylserine antibodies were estimated. In one case the IgG globulin fraction containing the inhibitor was separated. The activation rate of pure protein C to its activated form using thrombin/thrombomodulin as activator was then measured in the presence or absence of lupus anticoagulant. No overall decrease of protein C or protein S was detected in patients' plasma. Nevertheless, the lupus anticoagulant had a specific effect on the protein C system, inhibiting the catalytic activity of thrombomodulin without causing a functional protein C deficiency. This specific effect upon thrombomodulin can be a main cause, but not necessarily the only one, for the thrombophilic tendency of patients with the lupus anticoagulant.

[Thrombin-antithrombin III complexes as a measure of effective heparin treatment?]

To study the effect of heparin on thrombin formation in vivo, we measured thrombin-antithrombin III complexes (TAT) in 26 patients treated with heparin for acute coronary artery disease or deep vein thrombosis. There was a statistically significant correlation between activated partial thromboplastin time and heparin concentration, but none was found between these tests and TAT. Abnormal TAT values in 45% of the patients showed that therapeutic heparin concentration did not inhibit thrombin formation in vivo, or did so only partially.

Impaired fibrinolysis as an essential contribution to thrombosis in patients with lupus anticoagulant

Lupus anticoagulants (LA) are IgG or IgM antibodies against phospholipids which in vivo represent an important thrombophilic factor despite their in vitro anticoagulant activity. We investigated the fibrinolytic system of 20 patients with connective tissue disease and positive LA, compared to a control group of 24 age- and disease-matched patients without LA. There was no statistically significant difference of alpha 2-antiplasmin, plasminogen, fibrinogen, t-PA activity, D-dimers and heparin cofactor II, between the two groups. Although t-PA was uniformly low in both groups, plasminogen activator inhibitor activity (PAI) was significantly higher in LA cases (p less than 0.001). Increased PAI levels represent an inhibitory factor of the fibrinolytic defense mechanism, which together with other functional deviations may contribute to the thrombophilic tendency of LA patients.

[Thrombosis in a probable double heterozygote young man from an asymptomatic family with protein C deficiency and protein C dysfunction]

A family with combined quantitative and qualitative protein C deficiency is presented. The probably double heterozygote propositus with 7% residual amidolytic protein C activity had deep leg vein thrombosis at the age of seventeen. Other family members were asymptomatic.

Long lasting sitting position and haemostasis

Blood coagulation, fibrinolysis and platelet aggregability were assessed in 8 physicians aged 30-40 years, who had travelled non-stop by car from Salonica to Athens (510 km) and returned to Salonica after 48 h of rest and after administration of 1 g of aspirin. At the end of journey A, platelet aggregability was found to be increased (6 out of 8 persons), AT III was decreased by 30% (p less than 0.001), the F VIII:C / F VIIIR: Ag ratio was decreased (p less than 0.02) and ELT was prolonged. At the end of journey B the findings were the following: platelet aggregation was not affected, the decrease of AT III was not statistically significant and ELT was significantly shortened (p less than 0.005). A common finding of both journeys was the increase of platelet counts at the end (p less than 0.005). The correlation between long lasting sitting and the response of the haemostatic balance is suggested. The influence of aspirin is discussed.

The ratio MDA/MDAa as a new index of platelet hyperactivity

Since 1979, malonyldialdehyde (MDA) is considered a sensitive index of platelet hyperactivity. Stimulators of phospholipase A2 are used in the procedure of MDA production in order to obtain the final quantity (MDAa) which corresponds to the total amount of arachidonic acid present; without stimulation the production of MDA is minimal in non-activated platelets (MDA non-activated). Therefore, the more the MDA/MDAa ratio approaches unity, the more activated are the thrombocytes. We utilized for the first time this new index for the investigation of hyperactive platelets, and we studied 56 persons (17 patients with thrombophilic disease as group A, 17 normals as group B and 22 diabetics without ketoacidosis as group C). We proved that the new index (MDA/MDAa) can be used to detect persons with functionally hyperactive platelets because large differences are found between the mean values of normals and the values of patients with established thrombotic disease, at a high confidence limit (means +/- 3 SD covering 99% of the samples). Comparing the sensitivity of this new index with the other three methods used for the detection of hyperactive platelets [ratio of circulating platelet aggregates (CPA), aggregation with ADP, spontaneous aggregation] in groups B and C we found that only the ratio MDA/MDAa was able to reveal that (a) the two groups B and C are not identical (a statistical conclusion after comparison with the other methods) and (b) there were 5 diabetics in group C who had more hyperactive platelets than the others (these patients were not detected by any other method).