Fibrinolyse und Blutgerinnung bei ischämischer Herzerkrankung

Dieser Bericht gibt einen Überblick über die mit der Entwicklung der ischämischen Herzkrankheit (IH) verbundenen Abweichungen der Hämostase und auch über solche Abweichungen, die für die Entwicklung des akuten ischämischen Herzsyndroms von Bedeutung sein könnten.

Es wird gezeigt, daß Abweichungen im t-PA/PAI-1-System auf eine endotheliale Dysfunktion bei Patienten mit IH hinweisen. Es werden 3 Mechanismen vorgestellt, die eine derartige Endothelzelldysfunktion auslösen könnten, d.s. erhöhte Insulinproduktion, erhöhte Produktion von Entzündungsmediatoren und erhöhte Thrombinproduktion.

Schließlich wird die enge Beziehung zwischen Gerinnung und Fibrinolyse bei Patienten mit IH diskutiert. Die besprochenen experimentellen und klinischen Studien liefern gute Beweise dafür, daß die Reaktionen von t-PA und PAI-1 in den Endothelzellen miteinander verbunden sind und daß eine enge Beziehung zwischen der Bildung von Thrombin und der Produktion bzw. Freisetzung von t-PA und PAI-1 mit der Endotheizellfunktion bei Patienten mit IH besteht..

[Activated protein C resistance in patients with venous leg ulcer]

Patients with venous leg ulcers often show evidence of previous deep venous thrombosis. Resistance to activated protein C (APC-resistance) is an autosomal dominant inherited defect in the anticoagulant system which is a significant risk factor for development of venous thrombosis. APC-resistance was determined in plasma samples obtained from 46 unselected, consecutively admitted patients with venous leg ulcers, included during a six-month period. Twelve of the 46 patients (26%) (95% confidence limits: 14%-41%) had APC-resistance. APC-resistance is thus a common anticoagulant deficiency among venous leg ulcer patients and should be considered a risk factor for development of venous leg ulcer disease.

Inherited Protein S Deficiency in Venous Leg Ulcer Disease

Design:

Case report.

Setting:

University Hospital of Copenhagen.

Patients:

One patient presenting with venous ulceration of the leg after recurrent episodes of deep vein thrombosis which started at the age of 15 years.

Interventions:

Oral anticoagulation treatment and standard management of leg ulceration.

Main outcome measures:

Protein C, protein S and anti-thrombin III plasma levels were measured in the patient and her asymptomatic sister.

Results:

Plasma protein S levels were reduced in the index patient and her sister.

Conclusions:

We suggest that patients with venous leg ulcers attributable to post-thrombotic syndrome are investigated for abnormalities of the coagulation system.

[Copper-induced green hair. Treatment with a penicillamine containing shampoo]

A male patient with green hair is described. The cause was exogenous deposition of copper from domestic tap water which contained an increased copper concentration. The discolouration disappeared promptly following the use of a penicillamine containing shampoo.

Resistance to activated protein C: a common anticoagulant deficiency in patients with venous leg ulceration

Patients with leg ulcers caused by venous insufficiency often show evidence of previous deep venous thrombosis. Resistance to activated protein C (APC resistance) is a newly identified, autosomal dominant inherited defect in the anticoagulant system which significantly predisposes affected individuals to develop venous thrombosis. To elucidate the significance of APC resistance in venous leg ulcer patients, APC resistance was determined in plasma samples obtained from 46 unselected, consecutive patients with venous leg ulcers, admitted to hospital during a 6-month period. Twelve of the 46 patients (26%: 95% confidence limits, 14-41%) had APC resistance. APC resistance is thus a common anticoagulant deficiency among patients with venous leg ulceration and should be considered a risk factor for the development of venous leg ulcer disease.

[Asymptomatic sexually transmitted infections among HIV-tested persons]

We have prospectively determined the frequency of asymptomatic sexually transmitted diseases (STD) among patients seeking an HIV-test. In 246 patients, we observed 32 cases (13%) of asymptomatic STD, predominantly infections caused by Chlamydia trachomatis or human Papillomavirus. STD screening is of significance among patients seeking an HIV-test.

Vein surgery with or without skin grafting versus conservative treatment for leg ulcers. A randomized prospective study

In order for us to evaluate the efficiency of perforator vein surgery and skin grafting in leg ulcer patients, 47 patients were randomized into 3 treatment groups (group A: surgery for incompetent perforators, group B: surgery for incompetent perforators and ulcer excision followed by grafting, group C: control group). All the patients were treated with a compression bandage. When cellulitis was observed, a systemic antibiotic was given; eczema was treated with a steroid ointment. Fourty patients were evaluated regularly during one year after entry. There were no differences between the 3 treatment groups considering base-line characteristics, median ulcer size at entry and after one year. According to a review of the initial phlebograms, the occurrence of post-thrombotic changes in the deep veins were recorded in the majority of the legs. Our results suggest that ligation of incompetent perforators and skin grafting, as used in the present study, may not offer an additional advantage for venous ulcer patients with insufficiency of the deep veins when compared to conservative treatment. However, the removal of insufficient superficial veins was not studied.

Low anti-streptokinase IgG concentrations following streptokinase-streptodornase treatment of leg ulcer patients

We have evaluated whether neutralising anti-streptokinase IgG antibodies are produced following streptokinase-streptodornase therapy of leg ulcer patients. Serum anti-streptokinase IgG concentrations in 10 leg ulcer patients were determined before, and 1 week, 2 weeks, and 3 weeks following the treatment. We observed only a negligible increase in neutralizing anti-streptokinase IgG concentrations during the observation period, which was probably of no therapeutical significance.

[Plasmin-mediated activation of the coagulation system. A study of patients with acute ischemic heart disease treated with recombinant tissue-plasminogen activator]

We have studied the response of haemostatic reaction products in peripheral blood of patients with acute ischaemic heart disease receiving combined recombinant tissue type plasminogen activator/heparin therapy. We have found evidence that formation of excessive amounts of plasmin in vivo in relation to such therapy significantly enhances the degradation of fibrin, and of fibrinogen as well as the formation of thrombin. We conclude that excessive plasmin formation by thrombolytic therapy causes systemic effects including activation of coagulation.

Fibrinolysis in patients with acute ischaemic heart disease. With particular reference to systemic effects of tissue-type plasminogen activator treatment on fibrinolysis, coagulation and complement pathways

The plasminogen activator systems in the blood, the coagulation system, and the complement pathways are reviewed. The review describes the role of the vascular intima in activation of coagulation and fibrinolysis and the interrelations between the complement system and haemostatic mechanisms. Physiological activation of fibrinolysis may be triggered by and limited to fibrin because of a special affinity of plasminogen and plasminogen activators. The binding of plasminogen to fibrin is regulated by histidine-rich glycoprotein, and the primary physiological inhibitor of generated plasmin is alpha 2-antiplasmin and especially the plasminogen-binding form of this immediate plasmin inhibitor. Plasminogen activator inhibitors in the blood, that is, notably plasminogen activator inhibitor type 1 (PAI-1), bind circulating tissue-type plasminogen activator (t-PA). However, local fibrinolysis in vivo mediated by t-PA may be independent of complex formation between plasminogen activator inhibitors and t-PA in the fluid phase. Circulating plasminogen activator inhibitors might regulate fibrinolysis by increasing the clearance of t-PA from the blood. The urokinase-type and factor XII-dependent fibrinolytic proactivator system can be activated following t-PA-mediated generation of plasmin, and could thus serve as an amplification system of t-PA-induced fibrinolysis. It is claimed that the as yet uncharacterized proactivator is essential for optimal generation of plasminogen activator activity by the factor XII-dependent fibrinolytic system. The normal antithrombotic condition of the vascular intima probably results from lack of tissue factor activity and the presence of significant antithrombotic components comprising, among others, antithrombin III and the protein C-protein S system. A number of pathophysiologic stimuli, notably mediators of the acute phase response such as the cytokines interleukin-1 and tumour necrosis factor-alpha (cachectin), have the potential to induce the vascular endothelium to express procoagulant activity. Vascular endothelium promoting coagulant activity releases increased amounts of t-PA antigen and PAI-1 antigen into the circulation, and elevated levels in the blood of both may be regarded as a marker of a generalized procoagulant condition involving the vascular endothelium. In a prospective study in patients with unstable angina pectoris, patients in whom disease progresses and acute myocardial infarction develops, have increased amounts of t-PA antigen and PAI-1 antigen in the blood. This suggests that the procoagulant potential and atherosclerotic process of the vascular intima is more pronounced in the risk group.(ABSTRACT TRUNCATED AT 400 WORDS)

The fibrinolysis and coagulation systems in ischaemic heart disease. Risk markers and their relation to metabolic dysfunction of the arterial intima

This report reviews the major haemostatic deviations associated with the evolution of ischaemic heart disease (IHD) and also such deviations, which might be of importance for the evolution of the acute ischaemic heart syndrome. It is demonstrated that deviation in the t-PA/PAI-1 system indicate endothelial cell dysfunction in patients with IHD. Different factors which have the capability to induce such an endothelial cell dysfunction are proposed, i.e. hyperinsulinemia, mediators of chronic disease phase response, and thrombin. Finally, the intimate interrelation between coagulation and fibrinolysis in patients with IHD is discussed. The experimental and clinical studies reviewed provide good evidence that the endothelial cell response of t-PA and PAI-1 is coupled and that there is an intimate interrelation between generation of thrombin and production/release of t-PA and PAI-1 in IHD patients.

Depression of factor XII-dependent fibrinolytic activity in survivors of acute myocardial infarction at risk of reinfarction

Defective fibrinolysis may constitute a risk for the development of myocardial infarction in patients with ischaemic heart disease. We studied prospectively the factor XII-dependent plasminogen proactivator system in 49 survivors of an acute myocardial infarction. Blood samples were collected 8 weeks after hospital discharge. The factor XII-dependent fibrinolytic activity in the specimens was determined on fibrin plates after complete immuno-inhibition of the urokinase-like and the t-PA related fibrinolytic systems. During the subsequent follow-up period of 2.4 years, 10 patients developed recurrent myocardial infarction, whereas the remaining 39 patients did not. The reinfarction group of patients had a significantly lower median factor XII-dependent fibrinolytic activity (24.9 blood activating units (BAU).ml-1) than the patients without a relapse (41.9 BAU.ml-1, P < 0.02). Plasma concentrations of factor XII did not deviate significantly between the groups (P > 0.05), whereas the median plasma concentrations of prekallikrein was slightly lower in the reinfarction group (90%) than in the non-reinfarction group of patients (105%, P < 0.02). These observations point to an association between a depressed factor XII-dependent fibrinolytic activity and an enhanced risk of reinfarction in patients with a previous episode of acute myocardial infarction.

Reactive coagulation induced by plasmin in patients treated with recombinant tissue-type plasminogen activator

BACKGROUND

We and others have demonstrated that administration of thrombolytic agents causes the generation of thrombosis-promoting agents. At present, we have studied whether formation in vivo of excessive amounts of plasmin is responsible for the activation of coagulation in patients treated with recombinant tissue-type plasminogen activator.

METHODS

Modified crossed immunoelectrophoresis was used for determination of the plasminogen-binding form of alpha 2-antiplasmin. Enzyme-linked immunosorbent assay methods were used for determination of hemostatic reaction products.

RESULTS

The association between the generation of hemostatic reaction products and the exhaustion of the plasminogen-binding form of alpha 2-antiplasmin (PB alpha 2AP) was studied in 21 patients with acute myocardial infarction and 11 patients with unstable angina pectoris who were given a 3-hour, 100-mg intravenous infusion of recombinant tissue-type plasminogen activator (rt-PA). We observed in all patients a fall in blood concentrations of PB alpha 2AP (P < 0.01) after 2.25 hours of treatment and, simultaneously, a significant increase in fibrin degradation products (P < 0.01), D-dimer (P < 0.01), fibrinogen degradation products (P < 0.01), prothrombin fragment 1 + 2 (P < 0.01), and thrombin-antithrombin III complexes (P < 0.01). When we evaluated individual data, we observed high concentrations of the reaction products when the PB alpha 2AP concentration after 2.25 hours of treatment was lower than 25% of the pretreatment values. Also, we observed highly significant associations between the increase in the plasma concentrations of fibrin degradation products and thrombin-antithrombin III complexes (rs = 0.72; P < 0.01), the increase in plasma concentrations of fibrin degradation products and prothrombin fragment 1 + 2 (rs = 0.63; P < 0.01), the increase in plasma concentrations of D-dimer and thrombin-antithrombin III complexes (rs = 0.78; P < 0.01), and the increase in plasma concentrations of D-dimer and prothrombin fragment 1 + 2 (rs = 0.79; P < 0.01).

CONCLUSIONS

Generation of excessive amounts of plasmin is the main factor in producing the procoagulant response in patients who receive thrombolytic therapy with rt-PA, and intravenous heparin does not abolish this response. Plasmin inhibitors might be used in relation to thrombolytic therapy as indirect "antithrombotics."

Possible role of vascular intima for generation of coagulant activity in patients undergoing coronary thrombolysis with recombinant tissue-type plasminogen activator. A randomized, placebo-controlled study

In our present placebo-controlled study on recombinant tissue-type plasminogen activator (rt-PA) and heparin treatment of patients with acute ischaemic heart disease (IHD), we studied the extent of fibrin resolution and generation of coagulant activity. In rt-PA treated patients the lysis of fibrin in vivo (median 60 nmol of fibrin--estimated as fibrinogen equivalents) was significantly higher (p less than 0.02) than can be accounted for solely by lysis of a coronary thrombus (approximately 2 nmol) and circulating soluble fibrin (median 15 nmol). We observed a 200% increase of plasma concentrations of both prothrombin fragment 1 + 2 (p less than 0.001) and thrombin-antithrombin III complexes (p less than 0.001) as a consequence of rt-PA treatment, indicating that the coagulant activity is primarily caused by a physiological activation of the coagulation system. We conclude that an important contribution to the activation of coagulation in patients undergoing coronary thrombolysis is lysis of fibrin deposited widespread on the vascular intima, and that this process causes an intimal-dependent activation of the coagulation system.

Depression of factor XII-dependent fibrinolytic activity characterizes patients with early myocardial reinfarction after recombinant tissue-type plasminogen activator therapy

Twenty patients with acute myocardial infarction treated with recombinant tissue-type plasminogen activator (rt-PA) had endogenous factor XII-dependent fibrinolytic activity levels measured throughout the hospital period and those levels were prospectively correlated with the incidence of recurrent myocardial infarction until 8 weeks after hospital discharge. Within the follow-up period, recurrent myocardial infarction was observed in 8 patients, whereas the remaining 12 patients showed no clinical evidence of recurrence. The patients in the reinfarction group were characterized by a more pronounced depletion of and sustained lower levels of factor XII-dependent fibrinolytic activity than were the patients with no reinfarction (p less than 0.05). The decrease in fibrinolytic activity during rt-PA therapy was significantly associated with a depletion of functional alpha 2-antiplasmin, the primary plasmin inhibitor. These results indicate that, paradoxically, coronary thrombolysis with rt-PA involves depletion of endogenous factor XII-dependent fibrinolytic activity levels, which constitutes a risk for early myocardial reinfarction.

Long-lasting depression of the factor XII-dependent fibrinolytic system in patients with myocardial infarction undergoing thrombolytic therapy with recombinant tissue-type plasminogen activator: a randomized placebo-controlled study

In a randomized placebo-controlled study, seven patients with acute myocardial infarction allocated to intravenous treatment with 100 mg of recombinant tissue-type plasminogen activator (rt-PA) and seven patients allocated to placebo were studied during eight sampling periods before and after treatment. Seven patients with acute myocardial infarction treated intravenously with 1.5 million U of streptokinase were later studied during two sampling periods before and after treatment. The placebo group showed no significant deviations of endogenous factor XII-dependent fibrinolytic activity (p greater than 0.05). In the rt-PA group, this activity decreased significantly (p less than 0.001) after the infusion and remained depressed throughout the 1st 4 days. A significant decrease in activity (p less than 0.05) was also found in the streptokinase-treated patients. The depletion of factor XII-dependent fibrinolytic activity was not due to generation of inhibition or a depletion of factor XII, prekallikrein and plasminogen, but could be related to the proactivator of this system. It is concluded that rt-PA (and streptokinase) treatment in patients with acute myocardial infarction causes a prolonged depletion of factor XII-dependent fibrinolytic activity. This depression of endogenous fibrinolytic activity needs to be evaluated in relation to the enhanced risk of coronary reocclusion after thrombolytic therapy.

Early thrombolytic treatment reduces analgesic requirement in patients with myocardial infarction

The duration and amount of analgesics required were investigated in 67 patients with myocardial infarction treated with intravenous recombinant tissue-type plasminogen activator (rtPA) or placebo in a randomized double-blind trial. Infusion of rtPA (100 mg)/placebo was started within 5 h after the onset of symptoms, and the requirement for analgesics during the following 48 h was recorded. Sixty-seven per cent of the 30 rtPA-treated patients required analgesic treatment for less than 6 h, compared to 38% of the 37 patients in the placebo group (P = 0.04). During the study period, patients in the rtPA group used the equivalent of 5.3 mg (median value) intravenous morphine, which was significantly less than the 11.2 mg used in the placebo group (P = 0.04). In conclusion, the present study suggests that early thrombolysis with intravenous rtPA reduces the amount and duration of analgesic treatment required by patients with myocardial infarction.

Interrelationship between coagulant activity and tissue-type plasminogen activator (t-PA) system in acute ischaemic heart disease. Possible role of the endothelium

Patients with unstable angina pectoris (UAP; n = 20) and acute myocardial infarction (AMI; n = 34) were studied in the acute phase of ischaemic heart disease. We found significantly higher levels of thrombin-antithrombin-III (TAT) complexes, lower levels of systemic tissue plasminogen activator (t-PA) activity, and higher levels of plasminogen activator inhibitor (PAI) activity in the AMI patients compared to the UAP patients. In contrast to these specific changes, general acute phase reactants such as C-reactive protein, fibrinogen and von Willebrand factor did not differ significantly between the two groups. Studies of the relationship between coagulation (TAT-complexes) and fibrinolysis data revealed a significant positive correlation between plasma antigen concentrations of TAT-complexes and t-PA (P less than 0.02), and between TAT-complexes and PAI-I (P less than 0.002). These observations indicate a common pathophysiological mechanism underlying the changes in coagulation and fibrinolysis, suggesting that coagulation activity and t-PA-related fibrinolysis are interrelated processes in vivo, and probably take place at the level of the endothelial cell.

Specific, sensitive, precise, and rapid functional chromogenic assay of activated first complement component (C1) in plasma

We present a new functional assay for the first complement component (C1) in plasma, based on its activation by inhibition of the C1-esterase inhibitor (C1-inh) when monospecific antiserum to C1-inh is added to the plasma. After maximal activation, we can determine the concentration of activated C1 by using an amidolytic rate assay with a chromogenic substrate. We have optimized the assay conditions with respect to incubation time, concentration of antiserum to C1-inh, ionic strength, and pH. Our method determines specifically the concentration in plasma of free activated C1, not complexes of activated C1 with C1-inh, and is not influenced by the concentration of C1-inh in the test sample. Concentrations of C1 correlated significantly with activities determined by a hemolytic assay (r = 0.55, t = 4.09, P less than 0.001). The estimated interassay CV was 5% and the intra-assay CV was 1%. The sensitivity, imprecision, and practical test performance of our assay are superior to those of conventionally used hemolytic assays.

Specific, sensitive, precise, and rapid functional chromogenic assay of activated first complement component (C1) in plasma

We present a new functional assay for the first complement component (C1) in plasma, based on its activation by inhibition of the C1-esterase inhibitor (C1-inh) when monospecific antiserum to C1-inh is added to the plasma. After maximal activation, we can determine the concentration of activated C1 by using an amidolytic rate assay with a chromogenic substrate. We have optimized the assay conditions with respect to incubation time, concentration of antiserum to C1-inh, ionic strength, and pH. Our method determines specifically the concentration in plasma of free activated C1, not complexes of activated C1 with C1-inh, and is not influenced by the concentration of C1-inh in the test sample. Concentrations of C1 correlated significantly with activities determined by a hemolytic assay (r = 0.55, t = 4.09, P less than 0.001). The estimated interassay CV was 5% and the intra-assay CV was 1%. The sensitivity, imprecision, and practical test performance of our assay are superior to those of conventionally used hemolytic assays.

Enhanced generation and resolution of fibrin in women above the age of 30 years using oral contraceptives low in estrogen

Epidemiologic studies have suggested a relationship between the use of oral contraceptives and mortality from cardiovascular diseases in older women. Therefore we studied generation and resolution of fibrin in 28 healthy women above age 30 years, using oral contraceptives containing 30 to 50 micrograms of ethinyl estradiol. Thirty healthy nonusers served as control subjects. The oral contraceptive group had increased plasma concentration of thrombin-antithrombin III complexes (p less than 0.01), which indicated an enhanced generation of thrombin, increased plasma activity of tissue-type plasminogen activator (p less than 0.01), decreased plasma activity of plasminogen activator inhibition (p less than 0.01), and increased plasma concentration of fibrin degradation products (p less than 0.04). Interestingly, the ratio of thrombin-antithrombin III complexes/fibrin degradation products did not deviate significantly between groups. Twelve of the 28 women using oral contraceptives were light smokers, that is, less than 15 cigarettes per day. There were no differences in the determined variables between smokers and nonsmokers. Our study suggests that healthy women older than 30 years who use oral contraceptives containing 30 to 50 micrograms of ethinyl estradiol have an enhanced generation and resolution of fibrin, while the hemostatic balance is unaltered. These findings are unaffected by moderate cigarette smoking.

A depression of active tissue plasminogen activator in plasma characterizes patients with unstable angina pectoris who develop myocardial infarction

The balance between the coagulation system generating fibrin and its subsequent removal by the fibrinolytic system determines the fate of fibrin deposited in the vascular system. In a prospective study, selected haemostatic variables assessing this balance were determined in plasma samples from 20 consecutive patients admitted with unstable angina pectoris. Over a follow-up period of 6 years, eight patients developed myocardial infarction, whereas 12 patients did not. There was no significant difference between the two groups in the median plasma concentrations of thrombin-antithrombin III complexes reflecting the coagulant activity. The infarction group was characterized by a significantly lower median activity of tissue plasminogen activator in plasma euglobulins (P less than 0.05), a higher median concentration of tissue plasminogen activator antigen in plasma (P less than 0.05) and a tendency to higher plasma levels of antigenic and functional plasminogen activator inhibition. In all patients, the activities of tissue plasminogen activator inhibitor and of tissue plasminogen activator were significantly associated (rs = -0.4811, P less than 0.05). We conclude that a depressed fibrinolytic capacity attributable to a low tissue plasminogen activator activity is of pathogenetic importance for the development of myocardial infarction in patients with unstable angina pectoris.

Effects of methylamine and heparin on a rapid chromogenic assay of C1-esterase inhibitor in plasma

We describe a rapid assay of C1-esterase inhibitor (C1-inh) activity in plasma. After adding purified C1s serine protease (EC 3.4.21.42) in excess to plasma, we determine the residual C1s activity towards a new chromogenic tripeptide, CH3CO-Lys(CbO)-Gly-Arg-pNA. Optimal conditions include the addition of methylamine (final concentration 0.12 mol/L) to reduce the potential inhibitory capacity of alpha 2-macroglobulin towards C1s and the addition of heparin (final concentration 3000 int. units/L) to enhance the reaction of C1s with C1-inh. The correlation with C1-inh antigen concentrations in plasma was excellent. The estimated interassay CV was 4.3%, whereas the intra-assay CV was 2.0% for activity concentrations within the range of normal individuals (means +/- 2 SD: 70-124%), 1.3% at lower concentrations. The method is more convenient, rapid, and precise than previous methods, and C1-inh activity in plasma can be assessed within 30 min. We found that concentrations of C1-inh in plasma were low during open-heart bypass surgery.

Plasma HMW fibrinogen in patients with ischaemic heart disease

Fibrinogen has been reported to be a risk factor for development of myocardial infarction in patients with ischaemic heart disease. The functional properties of plasma high molecular weight (HMW) fibrinogen would suggest that this fibrinogen species is responsible for the association. In a prospective study with a follow-up period of 6 years the plasma concentrations of clottable fibrinogen and of HMW fibrinogen were related to the subsequent development of myocardial infarction in 53 patients admitted with ischaemic heart disease. Neither the concentrations of clottable fibrinogen nor of HMW fibrinogen in the 25 patients developing myocardial infarction deviated from the concentrations in the 28 patients with an uncomplicated course. A significant positive correlation between the concentrations of clottable fibrinogen and of HMW fibrinogen (rs = 0.58, p less than 0.001) suggests that HMW fibrinogen represents a major fraction of the clottable fibrinogen concentration in patients with ischaemic heart disease.

Effects of methylamine and heparin on a rapid chromogenic assay of C1-esterase inhibitor in plasma

We describe a rapid assay of C1-esterase inhibitor (C1-inh) activity in plasma. After adding purified C1s serine protease (EC 3.4.21.42) in excess to plasma, we determine the residual C1s activity towards a new chromogenic tripeptide, CH3CO-Lys(CbO)-Gly-Arg-pNA. Optimal conditions include the addition of methylamine (final concentration 0.12 mol/L) to reduce the potential inhibitory capacity of alpha 2-macroglobulin towards C1s and the addition of heparin (final concentration 3000 int. units/L) to enhance the reaction of C1s with C1-inh. The correlation with C1-inh antigen concentrations in plasma was excellent. The estimated interassay CV was 4.3%, whereas the intra-assay CV was 2.0% for activity concentrations within the range of normal individuals (means +/- 2 SD: 70-124%), 1.3% at lower concentrations. The method is more convenient, rapid, and precise than previous methods, and C1-inh activity in plasma can be assessed within 30 min. We found that concentrations of C1-inh in plasma were low during open-heart bypass surgery.

Depressed plasma fibrinolytic activity in a group of patients with connective tissue diseases

In various connective tissue disorders, a depressed fibrinolytic activity of the blood, attributed a contributory role in the development of disease, has been reported. We have determined selected fibrinolysis variables of the blood in 16 patients (7 patients with mixed connective tissue disease, 4 with systemic lupus erythematosus, 3 with rheumatoid arthritis and 2 with systemic sclerosis) and in 16 apparently healthy, age- and sex-matched controls. A significantly reduced mean activity of the intrinsic derived, urokinase-like plasminogen activator was found in the patient group. None of the other variables, including the extrinsic plasminogen activator (t-PA), differed from the control group. Possible implications of our findings in relation to the patho-physiology of these connective tissue diseases are discussed.