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M S Runge

Publications and source records attributed to M S Runge.

At least 73 records · Page 4Linked to original sources
PubMed1996

Patency trials with reteplase (r-PA): what do they tell us?

Thrombolytic therapy has been shown to reduce mortality and morbidity after acute myocardial infarction. Therapeutic benefit seems to be directly correlated with completeness of reperfusion (Thrombolysis in Myocardial Infarction [TIMI] grade 3 flow) of the infarct-related coronary artery, as well as the timeliness of reperfusion. To determine which regimen of reteplase (r-PA), a deletion mutant of wild-type tissue plasminogen activator (t-PA), is most effective for clinical thrombolysis, several reteplase regimens were compared with the most successful standard regimens of recombinant t-PA (alteplase) in 2 large-scale, randomized studies. All patients received aspirin and intravenous heparin. In the Reteplase Angiographic Phase II International Dose Finding Trial (RAPID-1), results in 606 randomized patients showed that a 10 + 10 U double bolus of reteplase was more effective than a 15 U single bolus, a 10 + 5 double bolus, or conventional alteplase (100 mg over 3 hours). In the Reteplase versus Alteplase Patency Investigation During Acute Myocardial Infarction (RAPID-2) trial, results in 324 patients showed that significantly more patients achieved patency of the infarct-related artery (TIMI grade 2 or 3 flow) at 90 minutes with reteplase (10 + 10 U double bolus) than with accelerated alteplase (100 mg over 90 minutes): 83.4% versus 73.3%, respectively (p = 0.03). The incidence of complete patency (TIMI grade 3 flow) at 90 minutes was likewise greater with reteplase than with accelerated alteplase (59.9% vs 45.2%, respectively; p = 0.01). At 60 minutes, the incidence of TIMI grade 2 or 3 flow was also significantly higher with reteplase than with alteplase (81.8% vs 66.1%, respectively; p = 0.01), as was the incidence of TIMI grade 3 flow (51.2% vs 37.4%, respectively; p < 0.031). The 35-day mortality rate was 4.1% for reteplase and 8.4% for alteplase (p = not significant). Reteplase and alteplase did not differ significantly with regard to the occurrence of severe bleeding (12.4% vs 9.7%, respectively) or hemorrhagic stroke (1.2% vs 1.9%, respectively). The results of these trials show that reteplase, given as a 10 + 10 U double bolus, achieves significantly higher rates of early reperfusion of the infarct-related coronary artery and is associated with significantly fewer acute coronary interventions when compared with front-loaded alteplase. The benefits of reteplase are achieved without any apparent increased risk of complications.

Cerebral Hemorrhage↗
PubMed1996

Role of hydroperoxyeicosatetraenoic acids in oxidative stress-induced activating protein 1 (AP-1) activity.

We have previously reported that hydrogen peroxide, an active oxygen species and a cellular oxidant, induces c-Fos and c-Jun mRNA expression and DNA synthesis in vascular smooth muscle cells and that these events require arachidonic acid release and metabolism through the lipoxygenase pathway. Here we have identified the eicosanoids that mediate the hydrogen peroxide-induced growth-related events in these cells. Hydrogen peroxide stimulated the production of 12- and 15-hydroperoxyeicosatetraenoic acids in vascular smooth muscle cells. Both 12- and 15-hydroperoxyeicosatetraenoic acids induced the expression of c-Fos and c-Jun protein and increased activating protein 1 (AP-1) activity, as measured by AP-1-DNA binding and AP-1-dependent human collagenase promoter-driven chloramphenicol acetyltransferase reporter gene transcription. Hydrogen peroxide and arachidonic acid also induced the expression of c-Fos and c-Jun protein and AP-1 activity. Nordihydroguaiaretic acid, an inhibitor of the lipoxygenase pathway, significantly inhibited both hydrogen peroxide and arachidonic acid-stimulated c-Fos and c-Jun protein expression and AP-1 activity. Together, these findings suggest that hydrogen peroxide induces the production of eicosanoids and that the eicosanoids are potential mediators of the oxidative stress-stimulated growth-related events in vascular smooth muscle cells.

Animals↗
PubMed1996

Cloning and identification of regulatory sequences of the human thrombin receptor gene.

Thrombin, via activation of vascular endothelial and smooth muscle cell thrombin receptors, modulates vascular wall healing. To understand the mechanisms that regulate human thrombin receptor (HTR) expression, we cloned and characterized the HTR gene. The HTR gene consists of Exon I, which contains the 5'-regulatory region and 85 nucleotides of coding sequence; a approximately 15-kb intron; and Exon II, which contains the remainder of the coding sequence and the entire 3'-untranslated region. Multiple transcription initiation sites were identified by S1 mapping and ribonuclease protection assay. DNA sequence analysis indicated the presence of two SP-1-AP-2 consensus binding sequences, near or within the transcription initiation sites, and consensus binding sequences for numerous regulatory proteins that potentially modulate HTR expression. Functional analysis of the HTR promoter was performed by transfecting human microvascular endothelial cells with HTR promoter region-luciferase constructs. The highest level of expression was obtained with a 0.7-kb promoter sequence and was progressively less with fragments of 0.54, 1.16, 1.6, and approximately3.2 kb. The data presented in this report provide a foundation for further characterization of the HTR gene and the mechanisms that regulate its expression within the blood vessel wall.

Amino Acid Sequence↗
PubMed1996

Enhanced thrombolytic and antithrombotic potency of a fibrin-targeted plasminogen activator in baboons.

BACKGROUND: Thrombolytic therapy reduces mortality in patients with acute myocardial infarction, but significant limitations exist with the use of currently available agents. In the present report, we describe the thrombolytic and antithrombotic potencies of a hybrid recombinant plasminogen activator consisting of an antifibrin antibody 59D8 (AFA) and low-molecular-weight single-chain urokinase-type plasminogen activator (scuPA). METHODS AND RESULTS: A thrombolysis model in which thrombi are preformed in vivo in juvenile baboons was developed to compare the potencies of AFA-scuPA, recombinant tissue plasminogen activator (rTPA), and recombinant scuPA (rscuPA) in lysing nonocclusive 111In-labeled platelet-rich arterial-type thrombi and 125I-labeled fibrin-rich venous-type thrombi. Systemic infusion of 1.89 nmol/kg AFA-scuPA produced thrombolysis that was comparable to that obtained with much higher doses of TPA (14.2 nmol/kg) and rscuPA (28.5 nmol/kg). When steady-state plasma concentrations are normalized, AFA-scuPA lyses thrombi sixfold more rapidly than scuPA and TPA (P < .001) and reduces the rate of formation more than comparable doses of rscuPA (P < .0001). At equivalent thrombolytic doses, AFA-scuPA produced fewer antihemostatic effects than either rTPA or rscuPA. Template bleeding time measurements were shorter (3.5 +/- 0.12 minutes for AFA-scuPA versus 5.3 +/- 0.36 and 5.2 +/- 0.04 minutes for rTPA and rscuPA, respectively; P < .05), alpha 2-antiplasmin consumption was less (P < .05), and D-dimer generation was lower (P < .05). CONCLUSIONS: We conclude that antibody targeting of scuPA to fibrin increases thrombolytic and antithrombotic potencies with less impairment of hemostasis compared with rTPA and rscuPA.

Animals↗
PubMed1996

Cyclic AMP inhibition of thrombin-induced growth in vascular smooth muscle cells correlates with decreased JNK1 activity and c-Jun expression.

Thrombin is a potent modulator of vascular tone and vascular smooth muscle cell (VSMC) mitogenesis. Early studies from other laboratories demonstrated that cyclic AMP (cAMP) antagonizes the mitogenic effects of platelet-derived growth factor and epidermal growth factor by inhibiting the extracellular signal-regulated protein kinases (ERKs; p42, p44) group of mitogen-activated protein kinases (MAPKs) in several cell types. This report examines the role of ERKs and Jun N-terminal kinase 1 (JNK1) groups of mitogen-activated protein kinases in thrombin-induced DNA synthesis in VSMCs using agents such as forskolin and dibutyrylcyclic AMP that increase intracellular cAMP levels. Both agents significantly inhibited thrombin-stimulated DNA synthesis in VSMCs. These agents, however, had no effect on thrombin induction of ERKs activation and c-Fos expression, suggesting divergence of the latter two events from the growth-signaling events of thrombin that are sensitive to inhibition by cAMP. Thrombin activated JNK1 and induced c-Jun expression in VSMCs in a time-dependent manner. In contrast to ERKs and c-Fos, thrombin-induced JNK1 activation and c-Jun expression were sensitive to inhibition by forskolin, suggesting an association of these events with thrombin-stimulated growth in these cells. Thrombin also increased AP-1 activity, and this response was significantly blunted by forskolin. Together, these results demonstrate a correlation between JNK1 activation and c-Jun expression by thrombin and their association with the mitogenic signaling events of thrombin in VSMCs.

Animals↗
PubMed1996

Evidence of hypoxia-inducible factor-1 in vascular endothelial and smooth muscle cells.

The hypoxia-inducible element (HIE-1), a 50-bp region just 3' to the human erythropoietin gene, has been found to regulate transcription in cells that do not ordinarily synthesize erythropoietin. We hypothesized that the HIE-1 and associated protein factors may have a role in transcriptional regulation in hypoxic vascular tissues. Therefore, tissues of vascular origin were grown in culture and exposed to hypoxia (1% 02, 5% CO2, balance N2) or normoxia (21% O2, 5% CO2). Human microvascular endothelial cells (HMEC-1) studied with electrophoretic mobility shifting demonstrated that HIE-1 was bound to a protein induced by hypoxia in these cells. HMEC-1 and rat aortic smooth muscle cells (RASM) were transfected with the vector pGL2-HIE-1. HMEC-1 reporter gene expression was 3.7 +/- 0.5-fold increased at 12 hours and 3.7 +/- 1.3-fold increased at 24 hours by hypoxia. RASM reporter gene expression was 18.6 +/- 6.5-fold (SEM) increased at 12 hours and 2.0 +/- 0.7-fold increased at 24 hours by hypoxia. These findings provide indirect evidence of a hypoxia-inducible factor in vascular cellular transcriptional regulation.

Aerobiosis↗
PubMed1996

The future of thrombolysis in the treatment of acute myocardial infarction.

The ability of thrombolytic therapy to lower mortality in patients with acute myocardial infarction was first demonstrated in 1986 by the Gruppo Italiano per lo Studio della Streptochinasi nell'Infarto Miocardico. In the ensuing 10 years, large efforts have been undertaken to develop more effective and safer thrombolytic agents. In addition, the value of adjunctive agents influencing thrombotic and thrombolytic processes was demonstrated, and newer agents are under active investigation. This review focuses on theoretical and practical aspects of optimizing thrombolytic therapy and on genetically engineered third generation plasminogen activators. Optimized thrombolytic therapy may make this form of therapy available to patients who are currently considered ineligible, and it will lead to earlier, more complete reperfusion of infarct-related coronary arteries. The benefits and risks of optimized thrombolytic regimens relative to those of mechanical reperfusion strategies will require constant reassessment while both forms of treatment develop.

Fibrinolytic Agents↗
PubMed1996

New approaches in plasminogen activator therapy.

Large efforts have been undertaken to develop more effective and safer thrombolytic agents than those currently used in clinical practice. In addition, the value of adjunctive agents influencing thrombotic and thrombolytic processes could be shown and newer agents are under active investigation. This review focuses on theoretical and practical aspects of optimizing thrombolytic therapy and mainly on genetically engineered, third generation plasminogen activators. Optimized thrombolytic therapy may make this form of therapy available to patients that are currently considered ineligible and it may lead to earlier, more complete reperfusion of infarct related coronary arteries. The benefits and risks of optimized thrombolytic regimens relative to mechanical reperfusion strategies will have to be constantly reassessed as both forms of treatment develop.

Fibrinolytic Agents↗
PubMed1996

Thrombolytic agents--an overview.

Thrombolysis today has become a routine option not only in the treatment of acute myocardial infarction but also in many other manifestations of thromboembolic disease. Until one decade ago, only two plasminogen activators, streptokinase and urokinase, were available for clinical use. They were characterized by limited thrombolytic potencies and major side effects including systemic fibrinogen breakdown, bleeds and stroke. This has prompted the search for new plasminogen activators with better pharmacological and clinical profiles. The first such new plasminogen activators were Anistreplase, a chemically modified version of the streptokinase-plasminogen-activator-complex and tissue-type plasminogen-activator produced by recombinant technology. Both new substances have fueled the development in modern thrombolytic treatment. While the clinical progress with t-PA was confirmed in large, double-blind, randomized, multicenter trials, no real superiority of anistreplase over the traditional plasminogen activators urokinase and streptokinase has been substantiated. While the clinical use of t-PA today has been established for acute myocardial infarction, pulmonary embolism and deep vein thrombosis, current research is focused on further plasminogen activators with further improved thrombolytic properties. This review summarizes the current knowledge on the biochemical and pharmacological properties of the first, second and future generation of plasminogen activators.

Fibrinolytic Agents↗
PubMed1996

Thrombolytic therapy in acute myocardial infarction--update 1996.

Despite the major advances made over the last decade, mortality following acute MI is still high for patients even if treated with the so far most effective "front-loaded" rt-PA regimen: 30-day-mortality is 6.3% and is associated with fatal cerebral haemorrhage in 1.5%. Further improvement of short- and long-term prognosis can be achieved if infusion of the thrombolytic agent starts early, if reperfusion occurs more rapidly and if a persistent TIMI grade 3 flow of the infarct-related artery can be achieved. These are prerequisites for optimal preservation of ventricular function and predictors of a favourable outcome.

Acute Disease↗
PubMed1996

Restenosis following percutaneous revascularization--the potential role of thrombin and the thrombin receptor.

Thrombin is present at sites of vascular injury and elicits many effects which may contribute to neointimal growth. Further studies are needed to order to determine steps involved in thrombin-induced effects and to identify potential sites to regulate these effects. The failure of the Helvetica trial to demonstrate an effect of treatment with hirudin on restenosis may relate more to our inability to safely inhibit thrombin than to a lack of a role for thrombin in restenosis. A therapy which enables safe and effective control of thrombin-induced responses following vascular injury may yet prove effective at reducing restenosis following percutaneous coronary revascularization.

Angioplasty, Balloon, Coronary↗
PubMed1995

Thrombin stimulates phosphorylation of insulin-like growth factor-1 receptor, insulin receptor substrate-1, and phospholipase C-gamma 1 in rat aortic smooth muscle cells.

It has recently been reported that protein-tyrosine kinase activity is required for thrombin-induced growth in vascular smooth muscle cells (VSMC). In the present study, we have identified several phosphoproteins that are tyrosine-phosphorylated in response to thrombin in quiescent VSMC. These proteins are insulin-like growth factor-1 receptor beta-subunit (IGF-IR beta), insulin receptor substrate-1 (IRS-1), and phospholipase C-gamma 1 (PLC-gamma 1). Thrombin-stimulated phosphorylation of these proteins was rapid; it was maximal at 1 min and reduced thereafter. Thrombin also activated mitogen-activated protein kinases (MAPK) in quiescent VSMC in a biphasic manner with a rapid and larger peak at 10 min (6-fold) followed by a sustained smaller second peak at 2 h (2-fold). Inhibition of protein-tyrosine kinase activity by the use of two structurally different protein-tyrosine kinase inhibitors, genistein and herbimycin A, significantly blocked the thrombin-induced tyrosine phosphorylation of IGF-1R beta, IRS-1, and PLC-gamma 1 and decreased thrombin-stimulated DNA synthesis. In contrast, however, inhibition of protein-tyrosine kinase activity had no effect on thrombin activation of MAPK. Collectively, these findings suggest a role for tyrosine phosphorylation of IGF-IR beta, IRS-1, and PLC-gamma 1 in thrombin-induced mitogenic signaling events in VSMC. Furthermore, while protein tyrosine phosphorylation is essential for thrombin-induced DNA synthesis, it is not required for thrombin-stimulated MAPK activation. Since thrombin rapidly activated Src in VSMC, Src may be involved in the cross-talk between the G-protein-coupled receptor agonist and a tyrosine kinase receptor such as IGF-1R.

Animals↗
PubMed1995

Growth-related responses in arterial smooth muscle cells are arrested by thrombin receptor antisense sequences.

The capacity of antisense sequences to the thrombin receptor to selectively inhibit thrombin receptor expression and limit mitogenic responses in vascular wall cells was investigated in vitro. Eight phosphorothioate oligodeoxynucleotides based on the sequences of the rat thrombin receptor (including sense, antisense, scrambled, and missense controls) were synthesized, characterized, and purified by high performance liquid chromatography. The antisense oligodeoxynucleotide (ODN 4) inhibitory effect was sequence-specific and both time-and concentration-dependent. A reduction in serum or alpha-thrombin-induced smooth muscle cell (SMC) proliferation was noted as early as 3 days at 30 microM (82%; 6.17 +/- 1.01 versus 34.08 +/- 3.89 x 10(4) cells/well; p < 0.05) and at a dose as low as 15 microM after 4 days in culture (19%; p < 0.05). Nonspecific effects were enhanced after prolonged exposure of SMC to the antisense oligodeoxynucleotide (> or = 6 days). A reduction of inositol phosphate generation greater than 50% (p < 0.05) was detected after exposure of SMC to antisense but not to sense or scrambled nucleotide sequences. This was observed after stimulation with both thrombin and SFFLRN (thrombin receptor peptide agonist). Northern blot analysis and enzyme-linked immunosorbent assays revealed 50 and 22% decreases, respectively, in thrombin receptor mRNA and protein (cell surface) levels in antisense oligonucleotide-treated (72 h) SMC as compared to untreated cells, suggesting that thrombin receptor down-regulation occurred at the pretranslational level. Thus, thrombin receptor-specific antisense sequences inhibit growth-related effects both of serum and thrombin on smooth muscle cells, potentially providing a new strategy for selective inhibition of receptor-mediated arterial injury responses.

Amino Acid Sequence↗
PubMed1995

Thrombin hypothesis of thrombus generation and vascular lesion formation.

Thrombin plays a central role in vascular lesion formation. It is the principal mediator of thrombogenesis, which is interrupted when direct antithrombins (including hirudin and its synthetic peptide analogs), thrombin receptor antagonist peptides, or thrombin generation inhibitors (including active-site inhibited factor VIIa, recombinant tick anticoagulant peptide, and omega-3 fatty acids) are used to block thrombin. Thrombin is also a potent growth factor, initiating smooth muscle cell proliferation at injury sites. In baboons, this reaction is 80% reduced by hirudin (p < 0.01). Thrombin also plays a role in modulating the effects of other growth factors such as platelet-derived growth factor (PDGF). Thus, Phe-Pro-Arg-CH2Cl prevents expression in baboons of PDGF-A mRNA induced by vascular injury due to balloon angioplasty; untreated mechanical injury results in a 3-fold increase in PDGF-A mRNA expression. Thrombin also regulates inflammatory processes, inducing expression both of leukocyte adhesion molecules and of their counterreceptors by endothelium.

Animals↗
PubMed1995

Role of the thrombin receptor in restenosis and atherosclerosis.

Thrombus generation is central to thrombosis at vascular lesion sites, including post-PCTA acute reocclusion and chronic restenosis. Thrombin stimulates platelet activation, monocyte and neutrophil chemotaxis, and endothelial production of prothrombotic factors. The varied physiologic effects of thrombin are due to the widespread presence of thrombin receptors in many cell types. The receptor is uniquely activated: thrombin binds to the receptor at the thrombin anion-binding exosite, the receptor ligand ("tethered ligand") apparently being a sequence of 6 amino acids (SFLLRN). Thus, peptides corresponding to the sequence of the tethered ligand can stimulate almost all functions of native thrombin itself. Several intracellular signaling pathways have been identified as important in the restenosis process: the G protein-related pathway, cyclic adenosine monophosphate (cAMP) mediator pathway, and tyrosine kinase activation pathway. In situ hybridization has demonstrated an increase in thrombin receptor mRNA throughout the period of neointimal and vascular lesion development. The mechanism of this increase is unknown, but may be mediated by multiple inflammatory modulators. Several strategies have been tested in animal models for inhibiting thrombin: (1) Hirudin not only prevents thrombin from cleaving fibrinogen, but also prevents thrombin receptor activation. (2) Thrombin receptor antagonist peptides block platelet aggregation effects of thrombin. (3) Mono- and polyclonal antibodies inhibit thrombin receptor activation. (4) Antisense oligonucleotides block thrombin receptor expression.

Acute Disease↗
PubMed1995

Hydrogen peroxide activation of cytosolic phospholipase A2 in vascular smooth muscle cells.

We have reported previously that hydrogen peroxide induces arachidonic acid release from prelabeled vascular smooth muscle cells. Here, we studied the effect of hydrogen peroxide on the phosphorylation of cytosolic phospholipase A2 in these cells. Hydrogen peroxide induced a rapid, time-dependent increase in the phosphorylation of cytosolic phospholipase A2. Hydrogen peroxide also increased arachidonic acid release from prelabeled cells in a time-dependent manner similar to that of phosphorylation of cytosolic phospholipase A2. Protein kinase C depletion significantly inhibited the hydrogen peroxide-stimulated cytosolic phospholipase A2 phosphorylation and arachidonic acid release. Hydrogen peroxide caused a time-dependent increase in mitogen activated protein kinase activity. Taken together, these findings suggest that cytosolic phospholipase A2 may, at least in part, contribute to arachidonic acid release induced by hydrogen peroxide and this effect appears to be mediated by protein kinase C and mitogen activated protein kinase.

Animals↗