Changes in coagulation and fibrinolysis markers in acute ischemic stroke treated with recombinant tissue plasminogen activator.

BACKGROUND AND PURPOSE: Shifts of the balance between coagulation and fibrinolysis play a crucial role in pathogenesis and treatment of cerebral ischemia. In this study, we characterized the kinetics of hemostatic abnormalities induced by acute ischemic stroke and its thrombolytic (recombinant tissue plasminogen activator [rtPA]) or anticoagulant (heparin) treatment. METHODS: Systemic generation of molecular markers of hemostasis (fibrin monomer, D-dimer, thrombin-antithrombin complex, and fibrinopeptide 1.2) was monitored in acute ischemic stroke, and the effects of thrombolytic and anticoagulant treatments were analyzed. RESULTS: Thrombolysis with rtPA induced a massive response of markers of coagulation activation and fibrin formation that peaked after 1 to 3 hours and persisted for up to 72 hours. In contrast, only minor hemostatic changes were induced by acute ischemic stroke itself. Administration of heparin did not significantly affect these hemostatic abnormalities. CONCLUSIONS: This first characterization of the coagulation activation induced by rtPA treatment for acute ischemic stroke and the failure to abolish such hemostatic abnormalities by heparin may be of value for further refinement of the currently discussed thrombolytic therapy and the controversial adjunctive anticoagulant prophylaxis in stroke patients.

Proinflammatory cytokines: indicators of infection in high-risk patients.

Proinflammatory cytokines play an eminent role in pathophysiology of infection and inflammation. Their actual clinical importance is, however, uncertain. In this study, we tested the hypothesis that inflammatory cytokines could be useful in detection of infections in high-risk patients. We prospectively studied the diagnostic value of determination of concentrations of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and the 55- and 75-kd soluble TNF receptors (sTNFR-p55 and sTNFR-p75) in detection of nosocomial infections in 52 patients with acute ischemic stroke, as an exemplary high-risk group, and compared these findings to those of conventional inflammatory indicators of inflammation (C-reactive protein and leukocyte count). After 1 week of hospitalization, 27% of the patients had minor or moderately severe nosocomial infections. This subpopulation exhibited significantly increased concentrations of IL-6 and sTNFR-p55 but not of IL-1beta, TNF-alpha, or sTNFR-p75. As expected, levels of C-reactive protein and leukocytes were increased in infected patients. The sensitivity and specificity for detection of nosocomial infections at day 7 of hospitalization was highest for IL-6, followed by C-reactive protein and the leukocyte count. The data suggest that the proinflammatory cytokine IL-6, in addition to its considerable pathophysiologic importance in systemic inflammation, may be valuable in detection of infections in high-risk patients.

Comparison of immunological and functional assays for measurement of soluble fibrin.

Various assays have been developed for quantitation of soluble fibrin or fibrin monomer in clinical plasma samples, since this parameter directly reflects in vivo thrombin action on fibrinogen. Using plasma samples from healthy blood donors, patients with cerebral ischemic insult, patients with septicemia, and patients with venous thrombosis, we compared two immunologic tests using monoclonal antibodies against fibrin-specific neo-epitopes, and two functional tests based on the cofactor activity of soluble fibrin complexes in tPA-induced plasminogen activation. Test A (Enzymun-Test FM) showed the best discriminating power among normal range and pathological samples. Test B (Fibrinostika soluble fibrin) clearly separated normal range from pathological samples, but failed to discriminate among samples from patients with low grade coagulation activation in septicemia, and massive activation in venous thrombosis. Functional test C (Fibrin monomer test Behring) displayed good discriminating power between normal and pathological range samples, and correlated with test A (r = 0.61), whereas assay D (Coa-Set Fibrin monomer) showed little discriminating power at values below 10 micrograms/ml and little correlation with other assays. Standardization of assays will require further characterization of analytes detected.

Proinflammatory cytokines in serum of patients with acute cerebral ischemia: kinetics of secretion and relation to the extent of brain damage and outcome of disease.

The release of the proinflammatory cytokines IL-1 beta, IL-6, TNF-alpha and soluble TNF-receptors p55 and p75 in peripheral blood was serially determined in 19 patients with acute cerebral ischemia. Only patients admitted within 4 h following onset of symptoms were studied. In contrast to serum levels of IL-1 beta, TNF-alpha and TNF-receptors, which did not exhibit a significant response, IL-6 showed a significant increase of serum levels already within the first hours following onset of disease and reached a plateau at 10 h until day 3 and returned to baseline by day 7. The increase of levels of this cytokine was significantly (P < 0.05) correlated with increasing volumes of brain lesion and was also significantly (P < 0.005) associated with poor functional and neurological outcome. The increase of levels of IL-6 despite a considerable dilution in peripheral blood shown in this preliminary study suggests an early inflammatory response in ischemic brain lesion.

Binding of a new monoclonal antibody against N-terminal heptapeptide of fibrin alpha-chain to fibrin polymerization site 'A': effects of fibrinogen and fibrinogen derivatives, and pretreatment of samples with NaSCN.

A novel murine monoclonal antibody against the fibrin alpha-chain N-terminus is presented, which reacts with desAA- and desAABB-fibrin. In immunoblot procedures, the antibody reacted with fibrin degradation products X and Y of non-crosslinked fibrin, and fragment E. No binding was observed to the fibrin fragment D-dimer, and fibrinogen fragments D and E. Minor binding to fibrinogen fragments X, and Y, and desBB-fibrin were presumably due to minor contamination with (desAA)-fibrin. A prerequisite for binding was release of fibrinopeptides A (FpA), the binding site being a fibrin-specific neo-epitope. No binding was observed to fibrinogen or to thrombin-treated dysfibrinogen MANNHEIM III (A alpha 16 Arg-->Cys) molecules, which do not release FpA. The antibody bound to abnormal fibrin molecules prepared from dysfibrinogen MANNHEIM I (A alpha 19 Arg-->Gly), albeit to a lesser extent than to normal fibrin. Binding of the antibody to the fibrin epitope was greatly enhanced by denaturation, e.g. by heat, or by treatment with chaotropic ions. Soluble fibrin in clinical samples is generally found as a complex with fibrinogen, since polymerization sites 'A' exposed by release of FpA react with complementary binding sites 'a' on the D-domains of other fibrin and fibrinogen molecules. Treatment of samples with NaSCN caused dissociation of fibrin monomer complexes. Reassociation was prevented by denaturation of both polymerization sites 'A' and 'a'. The antibody in combination with NaSCN-treatment of samples was useful for specific detection of fibrin monomer in plasma samples. Measurement was not influenced by fibrinogen degradation products, whereas fibrin degradation products at very high concentration caused some underestimation of fibrin monomer concentration.