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D Collen

Publications and source records attributed to D Collen.

At least 289 records · Page 16Linked to original sources
PubMed1993

Dynamic structural and functional relationships in recombinant plasminogen activator inhibitor-1 (rPAI-1).

The conformational characteristics of active, latent, and denatured recombinant plasminogen activator inhibitor-1 (rPAI-1) were compared using UV spectroscopy, spectrofluorimetry and circular dichroism (CD) techniques. The UV absorbance wavelength maxima in all preparations approximated 280 nm, while the extinction coefficients of active and latent rPAI-1 differed by up to 60%. When incubated at 37 degrees C, the A280 of latent rPAI-1 was quite stable while the A280 of active rPAI-1 spontaneously increased, eventually approximating that of latent rPAI-1. Alkali difference spectroscopy yielded markedly divergent titration patterns for active and latent rPAI-1, suggesting that the tyrosine residues present in active and latent rPAI-1 differ in terms of solvent exposure. At an excitation wavelength of 280 nm, active rPAI-1 exhibited the greatest relative fluorescence quantum yield. The relative fluorescence of latent and denatured rPAI-1 were less than that of active PAI-1, and the emission maxima of both species were slightly red-shifted in comparison to that of active rPAI-1, suggesting that at least one of the four tryptophan residues present in rPAI-1 is less exposed to the aqueous environment in the active form of the molecule. In contrast, the derived secondary structures based on CD of active and latent rPAI-1 were nearly identical, with both moieties exhibiting approx. 40% alpha-helix and 15% beta-sheet. Taken together, these spectroscopic data provide evidence supporting the hypothesis that active and latent PAI-1 differ in terms of their tertiary conformation and aromatic residue exposure, while their secondary structures appear generally comparable. Furthermore, denaturant-induced reactivation of latent rPAI-1 produces a partially active rPAI-1 with spectroscopic properties similar to that of latent rPAI-1, suggesting that denatured rPAI-1 more closely resembles the latent rPAI-1 conformation after refolding. The spontaneous spectroscopic changes observed in rPAI-1 may reflect conformational transitions that are critical to the regulation of endogenous PAI-1 activity.

Circular Dichroism↗
PubMed1993

Bio-immunoassay for staphylokinase in blood.

A bio-immunoassay (BIA) for the determination of staphylokinase (STA) activity in a plasma milieu has been developed. MA-7H11, a murine monoclonal antibody raised against STA, which has a high affinity for STA but does not interfere with the complex formation between plasmin(ogen) and STA or with plasminogen activation by STA, was coated on microtiter plates at a concentration of 4 micrograms/ml. STA-containing samples were incubated overnight at 4 degrees C and, after extensive washing, bound STA was quantitated by incubation with plasminogen (final concentration 0.5 microM) for 1 h at 37 degrees C, followed by determination of generated plasmin from the absorbance at 405 nm 10 min after addition of the chromogenic substrate S-2403 (final concentration 0.3 mM). Calibration curves constructed with natural (STAN) or recombinant (STAR) STA were linear between approximately 1 and 10 nM, with a lower detection limit of < or = 1 nM in buffer and in plasma of the human, baboon or hamster. Following bolus injection of STAR in hamsters, the disposition rate of STAR activity from plasma, determined with the BIA correlated very well (r = 0.98) with that of STAR-related antigen determined by ELISA, indicating that STAR is cleared in a functionally active form. The initial half-life was about 2 min, as determined with both methods. Following continuous intravenous infusion over 1 h in baboons, the plasma clearance of STAR activity, determined from the infusion rate and the steady-state plasma level of STAR activity, ranged between 45 and 62 ml/min for doses of STAR between 0.063 and 0.250 mg/kg.

Animals↗
PubMed1993

Molecular conversions of recombinant staphylokinase during plasminogen activation in purified systems and in human plasma.

Recombinant staphylokinase (STAR) is produced as a 136 amino acid protein with NH2-terminal sequence Ser-Ser-Ser (mature STAR, HMW-STAR), which may be converted to lower molecular weight forms (LMW-STAR) by removal of the first six residues (yielding STAR-delta 6 with NH2-terminal Gly-Lys-Tyr-) or the first ten residues (yielding STAR-delta 10 with NH2-terminal Lys-Gly-Asp-). In the present study the occurrence and effects of these conversions during plasminogen activation by HMW-STAR were studied in purified systems and in human plasma. In stoichiometric mixtures of HMW-STAR and native human plasminogen (Glu-plasminogen), rapid and quantitative conversion of HMW-STAR to LMW-STAR occurred, concomitant with exposure of the active site in the plasmin-STAR complex. NH2-terminal amino acid sequence analysis revealed the sequence Lys-Gly-Asp- in addition to the known sequences of the Lys-plasmin chains, identifying STAR-delta 10 as the derivative generated from HMW-STAR. In mixtures of catalytic amount of HMW-STAR and human plasminogen, plasmin generation occurred progressively, following an initial lag phase, during which HMW-STAR was converted to LMW-STAR. Plasmin-mediated conversion of HMW-STAR to LMW-STAR obeyed Michaelis-Menten kinetics with Km = 3.6 microM and k2 = 0.38 s-1. The specific clot lysis activities of HMW-STAR (122,000 +/- 8,000 units/mg) and LMW-STAR (129,000 +/- 8,000 units/mg) were indistinguishable. In an in vitro system consisting of a 60 microliters plasma clot submerged in 250 microliters plasma, 80% clot lysis within 1 h was obtained with 70 nM HMW-STAR.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Mechanisms of activation of mammalian plasma fibrinolytic systems with streptokinase and with recombinant staphylokinase.

The molecular basis of the marked interspecies variability in the response of plasma fibrinolytic systems to activation by streptokinase (SK) or recombinant staphylokinase (STAR) was studied using highly purified plasminogens and alpha 2-antiplasmins from five representative species (man, baboon, rabbit, dog and cow). Human plasminogen reacted rapidly and stoichiometrically with both SK and STAR to yield potent plasminogen activators (catalytic efficiencies, kcat/Km, of 1.0 microM-1 x s-1 and 0.3 microM-1 x s-1, respectively). The complex with SK was insensitive to alpha 2-antiplasmin, which, however, rapidly inhibited the complex with STAR (second-order rate constant, k1,app of 8 x 10(6) M-1 x s-1). In a system composed of a 0.06-ml 125I-fibrin-labeled plasma clot submerged in 0.30 ml plasma, both SK and STAR had potent fibrinolytic properties, causing 50% clot lysis in 2 h (EC50), with 120 nM and 13 nM, respectively. Clot lysis with SK was non-fibrin specific (residual fibrinogen < 10%), whereas lysis with STAR was highly fibrin specific (residual fibrinogen 76%). Canine plasminogen reacted avidly with SK, but SK was rapidly degraded; it reacted rapidly and quantitatively with STAR to form a potent plasminogen-activating complex (kcat/Km of 0.4 microM-1 x s-1) which was sensitive to neutralization by alpha 2-antiplasmin (k1,app of 6 x 10(5) M-1 x s-1). In a canine plasma milieu, SK was relatively potent (EC50 200 nM) and fibrin specific, whereas STAR was very potent (EC50 1.3 nM) but poorly fibrin specific. Baboon and rabbit plasminogen did not form stable stoichiometric complexes with SK, but reacted stoichiometrically and quantitatively with STAR. The complexes with STAR, however, had low catalytic efficiencies for the activation of their autologous plasminogens (kcat/Km 0.02 microM-1 x s-1) and reacted more slowly with alpha 2-antiplasmin (k1,app 5-10 x 10(5) M-1 x s-1). Bovine plasminogen was virtually unreactive towards both SK and STAR as well as to their complexes with human plasminogen, as monitored by measurement of the initial activation rates. The resistance to fibrinogen degradation with STAR observed in the human system could be transferred to the canine system by reconstituting canine plasma, depleted of plasminogen and alpha 2-antiplasmin, with the human proteins. Conversely, the sensitivity to fibrinogen degradation of the canine system could be transferred to the human system by reconstituting depleted plasma with canine plasminogen and alpha 2-antiplasmin. It is concluded that the variability in the response of mammalian plasma fibrinolytic systems to activation with SK or STAR is determined mainly by the extent of complex formation of these compounds with plasminogen, by the catalytic efficiencies of the complexes for the activation of autologous plasminogen and by the rate of inhibition of these complexes by alpha 2-antiplasmin.

Animals↗
PubMed1993

Regulation by alpha 2-antiplasmin and fibrin of the activation of plasminogen with recombinant staphylokinase in plasma.

The effects of alpha 2-antiplasmin and fibrin on the activation of plasminogen by recombinant staphylokinase (STAR) were studied in an effort to elucidate further the molecular basis of the fibrin-specificity of this fibrinolytic agent. In purified systems consisting of 1.5 mumol/L intact or low-M(r) plasminogen and 3 mumol/L alpha 2-antiplasmin, at 37 degrees C and in the absence of fibrin, STAR did not induce plasminogen activation and plasmin-alpha 2-antiplasmin complex (PAP) formation. Addition of a purified fibrin clot (30% vol at a concentration of 3 mg/mL) to mixtures containing intact plasminogen caused approximately 40% plasminogen activation within 2 hours, whereas in mixtures containing low-M(r) plasminogen, no activation was observed. In contrast, 10 nmol/L streptokinase (SK) induced 74% to 100% plasminogen activation within 2 hours in mixtures containing either intact or low-M(r) plasminogen, in both the absence and the presence of fibrin. In citrated human plasma in the absence of fibrin, 30 nmol/L STAR did not induce measurable plasminogen activation and PAP formation (< 1.5% within 2 hours), whereas addition of a plasma clot (12% vol) resulted in complete clot lysis and conversion of 19% +/- 8% of the plasminogen to PAP within 2 hours. Addition of a second plasma clot produced 23% +/- 2% additional plasminogen activation. Equipotent concentrations for plasma clot lysis of SK (100 nmol/L) induced 54% +/- 11% plasminogen activation in the absence and 49% +/- 16% in the presence of fibrin. Addition of 50 mmol/L 6-aminohexanoic acid (6-AHA) abolished the effect of fibrin on plasminogen activation with STAR, but not on activation with SK. In alpha 2-antiplasmin-depleted human plasma in the absence of fibrin, 30 nmol/L STAR did not induce fibrinogen breakdown (> 90% residual fibrinogen after 6 hours), whereas 30 nmol/L preformed plasmin-STAR complex induced extensive fibrinogen degradation (70% within 20 minutes). Thus, in the absence of fibrin, alpha 2-antiplasmin inhibits the activation of plasminogen by STAR, by preventing generation of active plasmin-STAR complex. Fibrin stimulates plasminogen activation by STAR via mechanisms involving the lysine-binding sites of plasminogen, probably by facilitating the generation of plasmin-STAR complex and by delaying its inhibition at the clot surface.

Antifibrinolytic Agents↗
PubMed1993

Functional properties of p-anisoylated plasmin-staphylokinase complex.

The kinetic and fibrinolytic properties of a reversibly acylated stoichiometric complex between human plasmin and recombinant staphylokinase (plasmin-STAR complex) were evaluated. The acylation rate constant of plasmin-STAR by p-amidinophenyl-p'-anisate-HCl was 52 M-1 s-1 and its deacylation rate constant 1.2 x 10(-4) s-1 (t1/2 of 95 min) which are respectively 50-fold and around 3-fold lower than for the plasmin-streptokinase complex. The acylated complex was stable as evidenced by binding to lysine-Sepharose. However, following an initial short lag phase, the acylated plasmin-STAR complex activated plasminogen at a similar rate as the unblocked complex, whereas the acylated plasmin-streptokinase complex did not activate plasminogen. These findings indicate that STAR, unlike streptokinase, dissociates from its acylated complex with plasmin in the presence of excess plasminogen. In agreement with this hypothesis, the time course of the lysis of a 125I-fibrin labeled plasma clot submerged in citrated human plasma, is similar for acylated plasmin-STAR, unblocked plasmin-STAR and free STAR (50% clot lysis in 2 h requires 12 nM of each agent). The plasma clearances of STAR-related antigen following bolus injection in hamsters were 1.0 to 1.5 ml/min for acylated plasmin-STAR, unblocked plasmin-STAR and free STAR, as a result of short initial half-lives of 2.0 to 2.5 min. The dissociation of the anisoylated plasmin-STAR complex and its consequent rapid clearance suggest that it has no apparent advantages as compared to free STAR for clinical thrombolysis.

Acylation↗
PubMed1993

Interaction between staphylokinase, plasmin(ogen), and alpha 2-antiplasmin. Recycling of staphylokinase after neutralization of the plasmin-staphylokinase complex by alpha 2-antiplasmin.

Although the plasminogen activating equimolar complex of staphylokinase (STA) with human plasmin is very rapidly inhibited by alpha 2-antiplasmin, STA is a potent fibrinolytic agent in a human plasma milieu which contains 1 microM alpha 2-antiplasmin. In the present study, it was found that the complex of plasmin with recombinant STA (STAR), after neutralization with alpha 2-antiplasmin, retained the full plasminogen activating potential of STAR when added to a plasminogen solution (93 +/- 5% residual activity). When added to human plasma containing a 125I-fibrin-labeled plasma clot, equi-effective concentrations (causing 50% lysis in 2 h) were 17 +/- 3.0, 13 +/- 1.0, and 20 +/- 1.0 nM for STAR, equimolar plasmin-STAR mixtures, and plasmin-STAR mixtures neutralized by alpha 2-antiplasmin, respectively. Gel filtration of mixtures of plasmin(ogen) and STAR revealed elution as plasmin-STAR complex (Mr approximately 100,000), whereas after addition of alpha 2-antiplasmin, STAR eluted with an apparent Mr of 20,000. When mixtures of plasmin and STAR were adsorbed to lysine-Sepharose, STAR adsorbed quantitatively (96 +/- 1%) to the gel, whereas it was nearly quantitatively recovered in the unbound fraction (92 +/- 4%) after addition of alpha 2-antiplasmin to the mixture. Scatchard analysis of the binding of STAR to plasmin-Sepharose yielded a dissociation constant of 55 nM, whereas no specific binding of STAR to plasmin-alpha 2-antiplasmin-Sepharose could be demonstrated. These findings indicate that, both in purified systems and in a human plasma milieu containing a 125I-fibrin-labeled plasma clot, neutralization of the plasmin-STAR complex by alpha 2-antiplasmin results in dissociation of functionally active STAR from the complex and recycling of STAR to other plasminogen molecules. This dissociation-recycling process may explain the high fibrinolytic potency of STAR in a plasma milieu in the presence of high concentrations of alpha 2-antiplasmin.

Amino Acid Sequence↗
PubMed1993

Comparative effects of enoxaparin and heparin on arterial and venous clot lysis with alteplase in dogs.

The effects of Enoxaparin with a specific anti-thrombin (anti-IIa) activity of 32 U/mg and a specific anti-factor-XA (anti-Xa) activity of 96 U/mg, and of heparin with a specific anti-IIa and anti-Xa activity of 192 U/mg, on thrombolysis with alteplase (Actilyse) were compared in a randomized blinded study using a combined arterial and venous thrombosis model in the dog. All dogs received an intravenous bolus of 5 mg/kg lysine-acetyl salicylate and 0.5 mg/kg alteplase over 60 min. Twenty-eight dogs were randomly assigned to seven treatment groups: placebo, Enoxaparin 1.5, 3 or 6 mg/kg, or heparin 0.5, 1 or 2 mg/kg, given as a 50% intravenous bolus and a 50% infusion over 2 h. Steady-state plasma levels ranged from 0.37 to 1.0 anti-IIa U/ml and 0.9 to 3.1 anti-Xa U/ml for Enoxaparin and from 0.4 to 2.3 anti-IIa U/ml and 0.42 to 3.2 anti-Xa U/ml for heparin. The activated thromboplastin time with 6 mg/kg Enoxaparin prolonged to 94 +/- 19 s and with 2 mg/kg heparin to > 150 s. The time to reflow was 120 +/- 36 min with placebo, 19 +/- 5 min with 6 mg/kg Enoxaparin (p = 0.03 vs control), and 22 +/- 5 min with 2 mg/kg of heparin (p = 0.03 vs control). Arterial patency, expressed in min reflow during the 180 min observation period correlated significantly with the dose of anticoagulant given (r = 0.73, p = 0.003 for Enoxaparin and r = 0.61, p = 0.012 for heparin).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

On the mechanism of the activation of human plasminogen by recombinant staphylokinase.

The mechanism of activation of human plasminogen by recombinant staphylokinase (STAR) was studied using the active site titrant p-nitrophenyl-p'-guanidinobenzoate (NPGB). NPGB prevented active site exposure in equimolar mixtures of plasminogen and STAR but reacted stoichiometrically with mixtures preincubated in the absence of titrant. Active site generation occurred progressively, with a marked initial lag phase followed by an exponential growth phase, and was associated with the conversion of single-chain plasminogen to two-chain plasmin. Incubation of mixtures of plasminogen and STAR with catalytic amounts (< 0.2% molar ratio) of preformed plasmin.STAR complex or of urokinase shortened the lag hase, whereas catalytic amounts (5% molar ratio) of the plasmin inhibitor alpha 2-antiplasmin delayed active site generation. The following kinetic model for the activation of plasminogen (P) by STAR (S) fits the experimental data, [formula: see text] and is described by [formula: see text] or [formula: see text] In this model, plasminogen and STAR produce an inactive complex (P.S), in which active plasmin.STAR (p.S) is generated in a rate limiting step, which is accelerated by plasminogen activators and delayed by plasmin inhibitors. At room temperature in a 0.1 M Veronal buffer, pH 8.3, containing 0.1 M arginine, the data are adequately fitted by the integrated equation with k1 = 4.0 x 10(-7) s-1 and k2 = 1.3 x 10(-2) microM-1 s-1. The k1 value could be explained by contamination of the plasminogen preparation with 3 ppm plasmin, converted by S to p.S. It is concluded that STAR activates plasminogen via a mechanism which differs in several essential aspects from that of streptokinase.

Amino Acid Sequence↗
PubMed1993

Pharmacokinetic and thrombolytic properties of chimeric plasminogen activators consisting of a single-chain Fv fragment of a fibrin-specific antibody fused to single-chain urokinase.

The pharmacokinetic and thrombolytic properties were determined of two recombinant single-chain chimeric plasminogen activators (PA) consisting of u-PA-33k, a low-molecular weight derivative of single-chain urokinase-type PA (scu-PA) comprising amino acids Ala132 through Leu411, and of either a single-chain variable region fragment (Fv) derived from the fibrin fragment D-dimer-specific monoclonal antibody MA-15C5 (K12G0S32) or of the deglycosylated single-chain Fv fragment obtained by substitution of Asn88 with Glu (K12G2S32). Following bolus injection in hamsters, clearances of recombinant scu-PA (rscu-PA) and of K12G0S32 were similar. In contrast, clearance of K12G2S32 was fourfold slower than that of rscu-PA. The thrombolytic potency (percent lysis per u-PA administered in milligrams per kilogram body weight) and specific thrombolytic activity (percent lysis per microgram per milliliter steady-state plasma u-PA antigen level) of these compounds were studied in hamsters with an experimental pulmonary embolus consisting of a human plasma clot injected via the jugular vein. The doses of K12G0S32 and K12G2S32 required to obtain maximal rate of clot lysis were sixfold and 11-fold lower than that of rscu-PA. The steady-state u-PA-related plasma antigen levels of K12G0S32 and K12G2S32 required to obtain maximal rate of clot lysis were 10-fold and fourfold lower than that of rscu-PA. Thus, targeting of K12G0S32 to the clot surface by means of its glycosylated Fv fragment results in a 10-fold increase of its specific thrombolytic activity and sixfold increase of its thrombolytic potency as compared with those of rscu-PA. Targeting of K12G2S32 to the clot surface by means of its deglycosylated Fv fragment results in only a twofold increase of its thrombolytic activity. However, its fourfold slower clearance, combined with its twofold higher specific thrombolytic activity, results in an 11-fold increase of its thrombolytic potency over that of rscu-PA. These findings indicate that the thrombolytic potency of chimeric antibody-targeted PA may be increased by increasing the specific thrombolytic activity, reducing the clearance, or both.

Amino Acid Sequence↗
PubMed1993

Interaction of staphylokinase with different molecular forms of plasminogen.

In order to obtain more information on the mechanism of plasminogen activation by staphylokinase (STA), we have studied the interaction between recombinant STA (STAR) and different molecular forms of human plasminogen, including Glu-plasminogen (native moiety), Lys-plasminogen (partially degraded moiety) and low-molecular-mass (LMM) plasminogen (moiety lacking kringles 1-4). Addition of 2 microM STAR to 0.4 microM Glu-plasminogen, Lys-plasminogen or LMM plasminogen resulted in the generation of proteolytic activity towards the chromogenic substrate D-Val-Leu-Lys-NH-PhNO2 (S-2251) corresponding to the exposure of 1 active center/plasminogen molecule. Complex formation was associated with conversion of the one-chain plasminogen moieties to two-chain plasmin, and with quantitative conversion of Glu-plasminogen to Lys-plasmin. The stoichiometry of the plasminogen-STAR complex, determined by binding of the complex to Lys-Sepharose and measurement of residual STAR, was found to be equimolar. The plasminogen-STAR complexes were inhibited by alpha 2-antiplasmin with second-order rate constants of 2.4 +/- 0.17 x 10(6) M-1 s-1 for Glu-plasminogen, 2.4 +/- 0.21 x 10(6) M-1 s-1 for Lys-plasminogen and 9.4 +/- 1.5 x 10(4) M-1 s-1 for LMM plasminogen. Glu-plasmin-STAR, Lys-plasmin-STAR and LMM plasmin-STAR had comparable catalytic efficiencies (kcat/Km) for the activation of Glu-plasminogen (0.24-0.29 microM-1 s-1), Lys-plasminogen (0.57-0.79 microM-1 s-1) or LMM plasminogen (0.11-0.16 microM-1 s-1). In a human plasma milieu in vitro STAR, Glu-plasmin-STAR, Lys-plasmin-STAR and LMM-plasmin-STAR were equally effective for the lysis of 125I-fibrin-labeled human plasma clots [50% clot lysis in 2 h (EC50) with 11-13 nM test compound] and equally fibrin-selective (residual fibrinogen levels of 72-84% after 2 h at EC50). Our results thus confirm that plasminogen and STAR form a 1:1 stoichiometric complex in which plasminogen is converted to plasmin and Glu-plasminogen to Lys-plasmin. The lysine-binding sites in kringles 1-4 of plasminogen are not required for the complex formation with STAR, nor for the enzyme activity of the complex with STAR in purified systems and in a human plasma milieu. The lysine-binding sites are, however, important for the rate of the inhibition of the complexes by alpha 2-antiplasmin.

Enzyme Activation↗
PubMed1993

Development of thrombolytic agents.

Despite their widespread use in patients with acute myocardial infarction, all currently available thrombolytic agents suffer from a number of significant limitations, including resistance to reperfusion, the occurrence of acute coronary reocclusion and bleeding complications. Furthermore, the therapeutic use of plasminogen activators as thrombolytic agents requires intravenous infusion of relatively large amounts of material. Therefore, the quest for thrombolytic agents with a higher thrombolytic potency, specific thrombolytic activity and/or a better fibrin-selectivity continues. Several lines of research towards improvement of thrombolytic agents are being explored, including the construction of mutants and variants of plasminogen activators, chimeric plasminogen activators, conjugates of plasminogen activators with monoclonal antibodies, or plasminogen activators from animal or bacterial origin.

Journal Article↗
PubMed1993

Short-term effects of early intravenous treatment with a beta-adrenergic blocking agent or a specific bradycardiac agent in patients with acute myocardial infarction receiving thrombolytic therapy.

OBJECTIVES: This study was conducted to explore mechanisms that could explain the possible clinical benefit of early administration of a beta 1-selective adrenoreceptor blocking agent or a bradycardiac drug as adjunct to thrombolysis in acute myocardial infarction. BACKGROUND: The effects of beta-blockers given concomitantly with thrombolytic therapy in patients with acute myocardial infarction have not been fully examined. The potential role of specific bradycardiac agents lacking negative inotropism as an alternative to beta-blockers in this setting has never been studied in humans. METHODS: In a double-blind study, we examined the effects of early intravenous and continued oral administration of a beta-blocker (atenolol), a specific bradycardiac agent (alinidine) or placebo on left ventricular function, late coronary artery patency, infarct size, exercise capacity and incidence of arrhythmias. RESULTS: A total of 292 patients with acute myocardial infarction of < or = 5 h duration and without contraindications to thrombolytic or beta-blocker therapy were studied. Of these, 100 were allocated to treatment with atenolol (5 to 10 mg intravenously followed by 25 to 50 mg orally every 12 h), 98 to alinidine (20 to 40 mg intravenously followed by 20 to 40 mg orally every 8 h) and 94 to placebo. All patients received 100 mg of alteplase over 3 h and full intravenous heparinization. No significant differences in coronary artery patency, global ejection fraction or regional wall motion were observed at 10 to 14 days among the three groups. Likewise, enzymatic and scintigraphic infarct size were also very similar. Neither atenolol nor alinidine was associated with a significant reduction in the incidence of arrhythmias during the 1st 24 h. No significant differences in clinical events were observed, with the exception of a greater incidence of nonfatal pulmonary edema in the atenolol group (6% vs. 1% in the alinidine group and 0% in the placebo group, p = 0.021). CONCLUSIONS: In the absence of contraindications, the administration of a beta-blocker or a specific bradycardiac agent together with thrombolytic therapy was safe. In this limited number of patients, these agents did not appear to enhance myocardial salvage or preservation of left ventricular function or to reduce the incidence of major arrhythmias in the early phase of infarction.

Adult↗
PubMed1993

Coronary thrombolysis with K1K2Pu, a chimeric tissue-type and urokinase-type plasminogen activator: a feasibility study in six patients with acute myocardial infarction.

BACKGROUND: K1K2Pu is a recombinant chimeric tissue-type and urokinase-type plasminogen activator consisting of the two kringle domains (K1 and K2) of human tissue-type plasminogen activator (t-PA) and the serine proteinase domain (Pu) of single-chain urokinase-type plasminogen activator (scu-PA). In experimental animal models of thrombosis, its thrombolytic potency has been shown to be five- to 10-fold greater than that of its parent molecules. METHODS: The effect of a bolus injection of K1K2Pu on coronary thrombolysis over 30 min was evaluated in six patients with acute myocardial infarction of less than 5 h duration in whom total occlusion of the infarct-related artery was confirmed using angiography. RESULTS: In two patients given an intravenous bolus of 10 mg over 5 min, persistent coronary artery recanalization was not observed within 30 min. In two out of four patients given a second bolus of 10 mg K1K2Pu, 15 min after the first, persistent coronary recanalization occurred within 30 min. The four patients without recanalization within 30 min were immediately given 100 mg t-PA over 90 min. In all patients the infarct-related artery was patent after 24 h, and the hospital course was uneventful. The bolus injections did not produce significant fibrinogen breakdown or alpha 2-antiplasmin consumption within 30 min. The plasma K1K2Pu level increased to 2-3 micrograms/ml after the first bolus injection and to 4-5 micrograms/ml after the second. K1K2Pu disappeared from the plasma with an initial half-life of 9 min and a clearance of approximately 50 ml/min. CONCLUSION: A bolus injection of 20 mg K1K2Pu is well tolerated and can induce clot-selective coronary thrombolysis in patients with acute myocardial infarction.

Aged↗