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Bär H, Bea F, Blessing E, Watson L, Wende P, Kreuzer J, Kübler W, Jahn L. Phosphorylation of cytokeratin 8 and 18 in human vascular smooth muscle cells of atherosclerotic lesions and umbilical cord vessels. Basic Res Cardiol 2001; 96:50-8. [PMID: 11215532 DOI: 10.1007/s003950170077] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Expression of cytokeratins (CK) is considered a hallmark of the state of epithelial differentiation. CK also occur in certain vascular smooth muscle cells (VSMC), inferring an association with a less differentiated phenotype. Recently, CK posttranslational modification was shown to occur in epithelial cells in stress, mitosis or apoptosis. The aim of this study was to determine potential CK phosphorylation patterns in human VSMC. Tissue samples of normal peripheral and coronary arteries, atherosclerotic lesions and umbilical cord vessels were evaluated by immunofluorescence microscopy applying antibodies specific for cytokeratins 8 and 18, specific cytokeratin phosphorylation sites, Ki-67-antigen as a proliferation marker and nick end labeling (TUNEL) to detect apoptosis. All samples contained cytokeratin-positive VSMC but diverse phosphorylation patterns. The C-terminal serine 431 of cytokeratin 8 (CK8Ser-431) was phosphorylated in the vast majority of CK-expressing VSMC of coronary artery lesions. Only a subset of these cells demonstrated phosphorylation of CK18Ser-33 or, to an even lesser extent, CK8Ser-73. DNA fragmentation occurred predominantly in samples containing cells with phosphorylated CK8Ser-431 domains. In contrast, occluded peripheral lesions exhibited little or no phosphorylation. Neonatal VSMC in umbilical cord vessels contain abundant phosphorylated CK domains, again predominantly CK8Ser-431, but also CK18Ser-33. Again, only single cells were found to be proliferating or to contain DNA fragmentation. Thus, abundant CK phosphorylation in VSMC of atherosclerotic lesions suggests a specific functional response to cell stress and a possible relation to apoptosis.
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Haberkorn U, Henze M, Altmann A, Jiang S, Morr I, Mahmut M, Peschke P, Kübler W, Debus J, Eisenhut M. Transfer of the human NaI symporter gene enhances iodide uptake in hepatoma cells. J Nucl Med 2001; 42:317-25. [PMID: 11216532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
UNLABELLED The characteristic feature of thyroid cells of taking up iodide enables benign thyroid diseases and differentiated thyroid carcinoma to be successfully treated with radioiodide therapy. The transport of iodide across the cell membrane is mediated by the human NaI symporter (hNIS). We therefore investigated whether the accumulation of iodide may be induced by the retroviral transfer of the hNIS gene in nonthyroid tumor cells. METHODS With use of a bicistronic retroviral vector for the transfer of the hNIS coding sequence and the hygromycin resistance gene, rat Morris hepatoma (MH3924A) cells were infected with retroviral particles and 32 hNIS-expressing cell lines were generated by hygromycin selection. After incubation of the genetically modified and wild-type hepatoma cells and the rat thyroid cell line FRTL5 with Na125I, the uptake and efflux of iodide were determined. In addition, the iodide distribution in rats bearing wild-type and genetically modified hepatomas was monitored. RESULTS Genetically modified MH3924A cell lines accumulated up to 235 times more iodide than did noninfected hepatoma cells. The maximal iodide uptake in the cells was observed after 60 min incubation time. Competition experiments in the presence of sodium perchlorate revealed a dose-dependent decrease of iodide uptake (87%-92%). Moreover, carbonyl cyanide p-trifluoromethoxyphenylhydrazone led to a loss of accumulated I- (32%), whereas 4,4'-diisothiocyano-2,2'-disulfonic acid stilbene increased the I- uptake into the cells (22%). However, a rapid efflux of the radioactivity (80%) was observed during the first 10 min after 125I(-)-containing medium had been replaced by nonradioactive medium. In rats, the hNIS-expressing tumors accumulated six times more iodide than did the contralateral wild-type tumor as monitored by scintigraphy. The ex vivo quantitation of the iodide content performed 1 h after tracer administration in 1 g of tumor tissue revealed a 17-fold higher iodide accumulation in the genetically modified tumors. In accordance with the in vitro data, we also observed a rapid efflux of radioactivity from the tumor in vivo. CONCLUSION The transduction of the hNIS gene per se is sufficient to induce 125I transport in Morris hepatoma cells in vitro and in vivo. With regard to a therapeutic application, however, additional conditions need to be defined that inhibit the iodide efflux from the tumor cells.
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Lutz S, Mura R, Baltus D, Movsesian M, Kübler W, Niroomand F. Increased activity of membrane-associated nucleoside diphosphate kinase and inhibition of cAMP synthesis in failing human myocardium. Cardiovasc Res 2001; 49:48-55. [PMID: 11121795 DOI: 10.1016/s0008-6363(00)00222-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
OBJECTIVE Chronic heart failure is associated with a decreased responsiveness of the heart to beta-adrenergic receptor agonists. We recently demonstrated a receptor-independent activation of G proteins and modulation of cardiac adenylyl cyclase activity by sarcolemmal membrane-associated nucleoside diphosphate kinase. We wondered whether changes in the activity of nucleoside diphosphate kinase occur in heart failure and contribute to or compensate for the impairment in myocardial receptor-mediated cAMP generation. METHODS Sarcolemmal membranes were purified from non-failing and failing human left ventricular myocardium. The protein level and activity of nucleoside diphosphate kinase were quantified. The influence of nucleoside diphosphate kinase on adenylyl cyclase activity was determined by measuring the effect of GDP on adenylyl cyclase activity in the absence and presence of nucleoside diphosphate kinase inhibitors. RESULTS The amount and activity of nucleoside diphosphate kinase in sarcolemmal membranes from failing hearts (n=13) were increased 3- to 4-fold compared to levels in membranes from non-failing myocardium (n=5). This increase in sarcolemmal nucleoside diphosphate kinase activity resulted in a 50% inhibition of adenylyl cyclase activity over a range of GDP and ATP concentrations. CONCLUSION The amount and activity of nucleoside diphosphate kinase are increased in sarcolemmal membranes of failing human myocardium, resulting in a substantial receptor-independent inhibition of adenylyl cyclase activity.
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Viedt C, Hänsch GM, Brandes RP, Kübler W, Kreuzer J. The terminal complement complex C5b-9 stimulates interleukin-6 production in human smooth muscle cells through activation of transcription factors NF-kappa B and AP-1. FASEB J 2000; 14:2370-2. [PMID: 11024008 DOI: 10.1096/fj.00-0468fje] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Activation of the complement system plays an important role in the pathogenesis of atherosclerosis. The proinflammatory cytokine interleukin (IL)-6 is potentially involved in the progression of the disease. We therefore investigated whether the terminal complement complex C5b-9 affects IL-6 production from vascular smooth-muscle cells (VSMC) and set out to determine the underlying signal transduction pathway. Stimulation of human VSMC with C5b-9 resulted in an increase of IL-6 transcript and production of IL-6 protein. Pretreatment with pertussis toxin or pyrrolidine dithiocarbamate inhibited complement-dependent IL-6 mRNA expression and IL-6 release, suggesting the involvement of Gi-proteins and nuclear factor-kB (NF-kB). C5b-9 also induced formation of reactive oxygen species, which, along with IL-6 release, was inhibited by the antioxidant N-acetylcysteine. C5b-9 activated the redox-sensitive transcription factors NF-kB and activator protein-1 (AP-1), which were both involved in the induction of IL-6 by C5b-9, as demonstrated by cis element double-stranded (decoy) oligonucleotides (ODN). The results demonstrate that activation of the complement system induces IL-6 release from human VSMC by a Gi-dependent pathway involving the generation of oxidative stressand the activation of the redox sensitive transcription factors NF-kB and AP-1. Our data support a new mechanism for the proatherogenic effect of the terminal complement complex.
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Voss F, Lü J, Schreiner KD, Bauer A, Becker R, Kübler W, Schöls W. Synkopenabklärung bei geriatrischen Patienten: Normalwerte, Komplikationen und Ergebnisse der invasiven elektrophysiologischen Untersuchung. ZEITSCHRIFT FÜR KARDIOLOGIE 2000; 89:1026-31. [PMID: 11149269 DOI: 10.1007/s003920070155] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Invasive electrophysiologic study (EPS) is an important tool in the assessment of patients with unexplained syncope. Especially in the elderly, the need for a complete diagnostic work-up is counterbalanced by the fear of complications associated with invasive procedures. Thus, the present study specifically addressed the question whether the risk/benefit ratio of EPS in geriatric patients with unexplained syncope justifies this invasive procedure. An invasive EPS was performed in 96 patients between 70 and 80 years and 21 patients older than 80 years. The control group consisted of 65 patients younger than 40 years. With increasing age, the diagnostic yield of EPS also increased (positive EPS finding in 20% of the control group and in 54% of the oldest patients). The majority of complications were of minor clinical significance and no significant differences were found between the three groups. Finally, no age-related difference in measured standard electrophysiological parameters was evident. Due to the high diagnostic value and the low complication rate, EPS can be recommended in elderly patients with unexplained syncope. An age-specific standardization of electrophysiologic parameters, measured during EPS, does not seem to be required.
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Tiefenbacher CP, Bleeke T, Vahl C, Amann K, Vogt A, Kübler W. Endothelial dysfunction of coronary resistance arteries is improved by tetrahydrobiopterin in atherosclerosis. Circulation 2000; 102:2172-9. [PMID: 11056088 DOI: 10.1161/01.cir.102.18.2172] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Tetrahydrobiopterin (BH4), an essential cofactor for the synthesis of NO, improves endothelial dysfunction after ischemia/reperfusion. Therefore, we hypothesized that reduction of BH4 is involved in the attenuation of endothelium-dependent vasodilation in atherosclerosis, and we investigated the effect of alterations of the BH4 level on the vasodilatory potential of coronary resistance vessels from humans and pigs with atherosclerosis. METHODS AND RESULTS Coronary arterioles were obtained from patients undergoing CABG (atherosclerosis group) or valve replacement (control group) and from pigs fed either a standard diet (control group) or atherogenic diet (atherosclerosis group). After isolation, vessels were cannulated, pressurized, and placed on the stage of an inverted microscope. Dose-response curves were investigated in response to the endothelium-dependent agonists histamine, serotonin, and acetylcholine (for pigs, substance P) and to the endothelium-independent agonist sodium nitroprusside (SNP) under control conditions and before and after incubation of the vessels with sepiapterin (substrate for BH4 synthesis). In vessels from patients and from animals with atherosclerosis, compared with vessels from the control groups, there was a significant (P:<0.05) reduction of vasodilation to all tested endothelium-dependent agonists but not to SNP. After application of sepiapterin, the responses to the endothelium-dependent agonists but not to SNP were significantly improved in vessels from the atherosclerosis groups. Sepiapterin did not influence vascular reactivity in the control groups. CONCLUSIONS Atherosclerosis severely compromises endothelial function of coronary resistance arteries. Administration of sepiapterin leads to a significant improvement of endothelium-dependent vasodilatation to different agonists in vessels from humans and pigs with atherosclerosis. Therefore, we conclude that a reduced availability of BH4 is involved in the development of endothelial dysfunction in atherosclerosis.
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Peter K, Kohler B, Straub A, Ruef J, Moser M, Nordt T, Olschewski M, Ohman ME, Kübler W, Bode C. Flow cytometric monitoring of glycoprotein IIb/IIIa blockade and platelet function in patients with acute myocardial infarction receiving reteplase, abciximab, and ticlopidine: continuous platelet inhibition by the combination of abciximab and ticlopidine. Circulation 2000; 102:1490-6. [PMID: 11004138 DOI: 10.1161/01.cir.102.13.1490] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Improvement of thrombolysis may be achieved by concomitant strong platelet inhibition. To monitor platelet function in patients with myocardial infarction (n=46) who were treated with the fibrinolytic agent reteplase, the glycoprotein (GP) IIb/IIIa blocker abciximab, and the ADP receptor antagonist ticlopidine, we developed a flow cytometric assay. METHODS AND RESULTS Binding of abciximab to platelets was directly monitored as the percentage of platelets stained by a goat anti-mouse antibody. Blood drawn 10 minutes and 2 hours after the start of therapy with reteplase and abciximab and during the 12-hour infusion of abciximab demonstrated a maximal blockade of GP IIb/IIIa (10 minutes, 86.2+/-10.3%; 12 hours, 85.8+/-7.1%). Starting at 24 hours, abciximab binding gradually decreased (24 hours, 74.6+/-16.2%; 48 hours, 66.8+/-14.9%; 72 hours, 60.5+/-16.7%; 96 hours, 49.4+/-17.8%; 120 hours, 35.8+/-16. 4%; and 144 hours, 29.9+/-15.3%). Binding of a chicken anti-fibrinogen antibody to platelets, indicating the level of functional blockade of GP IIb/IIIa, was inversely correlated with the binding of abciximab (r=-0.72, P:<0.0001). In blood drawn at 10 minutes, platelet aggregation was maximally inhibited but recovered within 48 hours even if the majority of GP IIb/IIIa receptors were still blocked by abciximab. Reteplase did not influence abciximab binding and did not activate platelets, as measured by P-selectin expression, fibrinogen binding, and platelet aggregation. Platelet inhibition that was achieved during the first 24 hours by abciximab was directly maintained by additional treatment with ticlopidine. CONCLUSIONS Flow cytometric monitoring of platelet function allows differentiation of the effects of reteplase, abciximab, and ticlopidine. The combination of abciximab and ticlopidine is an attractive therapeutic strategy that provides a fast and continuous platelet inhibition.
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Hauer K, Niebauer J, Weiss C, Marburger C, Hambrecht R, Schlierf G, Schuler G, Zimmermann R, Kübler W. Myocardial ischemia during physical exercise in patients with stable coronary artery disease: predictability and prevention. Int J Cardiol 2000; 75:179-86. [PMID: 11077132 DOI: 10.1016/s0167-5273(00)00321-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AIMS We assessed whether exercise-induced myocardial ischemia during intensive group exercise sessions can be predicted in patients with coronary artery disease and stable angina pectoris. METHODS AND RESULTS Twenty-three patients underwent cardiac catheterization, 201-thallium scintigraphy, and exercise testing prior to participation in group training sessions. Heart rates and myocardial ischemia were documented by Holter monitoring. The individual training heart rate was calculated as a percentage of the maximal heart rate achieved during symptom-limited exercise testing. Myocardial ischemia occurred significantly more often during group exercise sessions (15 of 23 patients) than during treadmill testing (4 of 23 patients, P<0.001). Maximal heart rate (145+/-23 vs. 134+/-21 beats/min, P<0.004) and maximal plasma lactate concentrations (6.0+/-2.9 vs. 4.3+/-2.0 mmol/l, P<0.05) were significantly higher than during symptom-limited exercise testing. Ischemic episodes occurred significantly more often during jogging than during competitive ball games or interval training. Myocardial ischemia occurred in patients who exceeded their individual target training heart rates (43 of 44 episodes; P<0.001). Duration of ischemic episodes did not correlate with any marker obtained at the beginning of the study. CONCLUSION These data demonstrate that routine diagnostic procedures do not sufficiently identify patients at risk for exercise-induced myocardial ischemia. Ischemic events are only effectively prevented by choosing adequate types of exercise and, above all, by the strict adherence to individual target heart rates.
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Grünig E, Janssen B, Mereles D, Barth U, Borst MM, Vogt IR, Fischer C, Olschewski H, Kuecherer HF, Kübler W. Abnormal pulmonary artery pressure response in asymptomatic carriers of primary pulmonary hypertension gene. Circulation 2000; 102:1145-50. [PMID: 10973844 DOI: 10.1161/01.cir.102.10.1145] [Citation(s) in RCA: 179] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Familial primary pulmonary hypertension (PPH) is an autosomal-dominant inherited disease with incomplete penetrance and poor prognosis. This study was performed to examine whether asymptomatic carriers of a mutated PPH gene can be identified at an early stage by their pulmonary artery systolic pressure (PASP) response to exercise. METHODS AND RESULTS Stress Doppler echocardiography during supine bicycle exercise and genetic linkage analysis were performed on 52 members of 2 families with PPH. In 4 PPH patients, the mean PASP was increased at rest (73+/-16 mm Hg). Fourteen additional family members with normal PASP at rest revealed an abnormal PASP response to exercise (from 23+/-4 to 56+/-11 mm Hg) without secondary cause (abnormal response [AR] group). Twenty-seven other members (NR group) revealed a normal PASP response (maximal pressure <40 mm Hg) to exercise (from 24+/-4 to 37+/-3 mm Hg, P<0. 0001). All 14 AR but only 2 NR members shared the risk haplotype with the PPH patients. The molecular genetic analysis supported linkage to chromosome 2q31-32 with a logarithm of the odds score of 4.4 when the 4 patients and the 14 AR members were classified as affected. CONCLUSIONS We conclude that the pathological rise of PASP in asymptomatic family members is linked to chromosome 2q31-32 and is probably an early sign of PPH. Therefore, stress Doppler echocardiography may be a useful tool to identify persons at risk for PPH even before pulmonary artery pressures at rest are elevated.
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Opie LH, Yusuf S, Kübler W. Current status of safety and efficacy of calcium channel blockers in cardiovascular diseases: a critical analysis based on 100 studies. Prog Cardiovasc Dis 2000; 43:171-96. [PMID: 11014332 DOI: 10.1053/pcad.2000.7010] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Recently, serious concerns have been expressed about the long-term safety of the calcium channel blockers (CCBs) as a group. Safety and efficacy are, however, ultimately linked to each other; therefore both must be evaluated especially in the therapy of angina and hypertension, the main clinical indications for CCBs. The structural, functional, and pharmacokinetic heterogeneity of CCBs means that the efficacy and dangers of one subclass, such as the short-acting dihydropyridines (DHPs), in one situation, such as unstable angina, do not necessarily apply in other clinical situations. One hundred studies are reviewed according to their methods of data collection: case series, case control, cohort, randomized controlled trials (RCTs), and meta-analyses. Large, well-designed RCTs and the meta-analyses based on these trials remain the gold standard. Observational studies, though potentially less reliable sources of information because of selection bias, may nevertheless produce hypotheses that must then be tested in RCTs. Regarding safety, both observational studies and RCTs suggest that adverse effects of CCBs may be linked to short-acting agents, specifically short-acting nifedipine. Two good studies favor the safety of verapamil, even in short-acting form. Incomplete but increasing overall evidence favors the safety of longer-acting DHPs. Heart failure remains a class contraindication to the use of all CCBs, with some exceptions. Regarding efficacy, there are positive results of RCTs with CCBs in 2 specific clinical situations, namely, verapamil in postinfarct protection in the absence of pre-existing heart failure, and 2 outcome studies on hypertension with longer acting DHPs. These results cannot automatically be applied to other clinical situations and to other CCBs. For example, there is no evidence for the safety or efficacy of DHPs used without beta blockers in postinfarct patients. In diabetic hypertensives, 2 relatively large RCTs show that the blood pressure can be reduced by DHP-based therapy in diabetics, with a reduction in hard end points. To achieve current blood pressure goals, combination therapy is almost always necessary, and in diabetics there is strong evidence that 1 essential component should be an angiotensin converting enzyme inhibitor. The future aim with CCBs must be to obtain a large database gathered from RCTs, which will give the same certainty about efficacy and safety that already holds for use of the diuretics in hypertension, beta-blockers in postmyocardial infarction patients, and the angiotensin converting enzyme inhibitors in heart failure.
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Salbach PB, Brückmann M, Turovets O, Kreuzer J, Kübler W, Walter-Sack I. Heparin-mediated selective release of hepatocyte growth factor in humans. Br J Clin Pharmacol 2000; 50:221-6. [PMID: 10971306 PMCID: PMC2014977 DOI: 10.1111/j.1365-2125.2000.00246.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
AIMS The aim of this investigation was to compare the effects of standard (S) with low molecular weight (LMW) heparin on circulating levels of heparin-binding growth factors (HBGF), known to have angiogenic properties in humans. METHODS In two consecutive trials 18 healthy male volunteers were studied on three separate occasions, following a placebo-controlled crossover design. Subjects were randomised to receive either S-heparin or LMW heparin or placebo. Heparins were administered either by intravenous (i.v.) or subcutaneous (s.c.) injection and saline placebo by i.v. injection. Serum concentrations of hepatocyte growth factor (HGF), vascular endothelial cell growth factor (VEGF) and basic fibroblast growth factor (bFGF) were measured before and up to 24 h after injection. RESULTS Administration of i.v. S-or LMW-heparin (50 IU kg(-1) resulted in rapid, highly significant (47 fold for S, 30.9 fold for LMW) increases in HGF serum values, reaching maxima of 10.51+/-1.65 ng ml(-1) (S) and 8.28+/-1.04 ng ml(-1) (LMW), respectively, 10 min after drug application. S.c. injection of S-heparin or LMW heparin resulted in 4.1 and 5.4 fold increases in HGF serum values, respectively. Both agents showed no effects on circulating VEGF or bFGF levels, independent of the route of administration. CONCLUSIONS Circulating HGF levels were selectively increased in response to pharmacological doses of two, widely used heparin preparations. This may, in part, explain some of the biological effects of heparin separate from its anticoagulant properties. By this mechanism, the systemic administration of heparin may facilitate collateral vessel formation in various clinical settings of tissue ischaemia.
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Kübler W. [Scientific cooperation: significance for the clinic and industry]. ZEITSCHRIFT FUR KARDIOLOGIE 2000; 89:807-9. [PMID: 11077692 DOI: 10.1007/s003920070186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Kiessling F, Becker D, Ullisch EV, Kübler W, Haller C. Influence of intercellular junctions on endothelin secretion of human umbilical vein endothelial cells in vitro. Basic Res Cardiol 2000; 95:299-307. [PMID: 11005585 DOI: 10.1007/s003950070049] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The endothelium plays a pivotal role in the rheological regulation of blood flow by the secretion of vasoactive factors. The interaction between shear forces and the endothelium is determined by the mechanical properties of the endothelial cell layer which are associated with intercellular junctions. Cell-cell contacts could therefore modulate the secretion of vasocative factors in response to rheological stimuli. We investigated the relationship between intercellular junctions and the secretion of the vasoconstrictor peptide endothelin and the coagulation co-factor von Willebrand factor (vWF). Human umbilical vein endothelial cells (HUVECs) were used as in vitro endothelial model system. Intercellular junctions were reversibly disrupted by calcium chelation or hypertonic stress; alternatively, the formation of intercellular junctions was inhibited by culturing the cells in suspension or by plating them in the presence of an inhibitory anti-VE-cadherin antibody. The opening of intercellular junctions was verified by assessing transmonolayer electrical resistance (TMR) and immunofluorescence morphology. The concentration of endothelin and vWF was measured in the cell culture supernatants using specific ELISAs. The secretion of endothelin was inhibited by EGTA (5 mM) and stimulated by incubation with tumor necrosis factor alpha (TNFalpha, 40 ng/ml). Treatment with hypertonic medium (glycerol, 1,200 mosmol/l) for 10 minutes opened intercellular junctions and markedly reduced the secretion of endothelin. HUVECs in suspension culture did not secrete endothelin and failed to respond to TNFalpha, but readily resumed these functions upon forming a new monolayer on plastic. The reconstitution of intercellular junctions after suspension culture could be inhibited using a specific anti-VE-cadherin antibody. This antibody, but not a non-specific anti-human-IgG antibody reduced endothelin secretion. The secretion of von Willebrand Factor was less dependent on intercellular junctions. The opening of intercellular junctions did not induce cell death, since the cells continued to exclude trypan blue. The results of this study suggest a novel and potentially pathophysiologically/clinically relevant correlation between intercellular junctions and the secretion of endothelin in endothelial cells.
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Viedt C, Mereles D, Kübler W, Kreuzer J. [Fibrinolytic therapy in thrombosis of a mitral valve prosthesis]. ZEITSCHRIFT FUR KARDIOLOGIE 2000; 89:698-701. [PMID: 11013975 DOI: 10.1007/s003920070198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A 48-year-old woman presented with progressive dyspnea due to thrombosis of a mitral valve prosthesis. The patient had undergone mitral valve replacement (St. Jude Medical) six years prior to admission because of mitral stenosis (Class III); three years later the prosthesis had to be replaced (St. Jude Medical) because of valve thrombosis. At admission, transesophageal echocardiography showed a thrombus on the atrial side of the fixed valve leaflet and a thrombus (2.4 x 1.6 cm) floating from the left atrial roof. Because of the previous thoracotomies, thrombolysis was initiated despite the mobile thrombus with the attendant risk of embolization. Urokinase was infused in a dose to maintain the fibrinogen level around 100 mg/dl. After 24 h, the mean pressure gradient across the prosthetic mitral valve (measured by doppler echocardiography) had decreased from 23 to 11 mmHg. After 13 days of this modified thrombolytic regimen, the clinical symptoms of the patient had resolved and echocardiography showed a normal function of the prosthetic mitral valve without evidence of residual thrombosis. This patient demonstrates that prolonged cautious thrombolysis can be effective for the treatment of prosthetic valve thrombosis in hemodynamically moderately compromised patients.
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Meyer FJ, Zugck C, Haass M, Otterspoor L, Strasser RH, Kübler W, Borst MM. Inefficient ventilation and reduced respiratory muscle capacity in congestive heart failure. Basic Res Cardiol 2000; 95:333-42. [PMID: 11005589 DOI: 10.1007/s003950070053] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The extent and time-course of changes in lung volumes, ventilatory efficiency at rest and during exercise, and respiratory muscle function and their influence on exercise limitation in congestive heart failure (CHF) are unclear. It is unknown whether respiratory muscle function may predict changes in exercise limitation or may be impaired in patients with poor outcome. 145 male patients (54 +/- 1 years) suffering from CHF (NYHA class I-III, mean 2.3 +/- 0.1), with a LVEF of 23 +/- 1%, and a mean peak O2 uptake (VO2peak) 15.0 +/- 0.5 mL X min(-1) X kg(-1), were studied. They were grouped in Weber functional classes A to D according to their VO2peak. Significant increases in ventilatory equivalents for O2 and CO2 (VE/VCO2peak) and in dead space ventilation at rest and during exercise were found with increasing exercise limitation. Moreover, there was a correlation of static and dynamic lung volumes (inspiratory vital capacity, IVC, r = 0.43, P < 0.01), as well as of maximal inspiratory pressure (MIP; r = 0.46, P < 0.01) with VO2peak. Patients who died (n = 26) or were heart transplanted (n = 20) during a follow-up (mean 800 +/- 10 days) had a reduced MIP (6.4 +/- 0.4 kPa) as compared with survivors (n = 82; 9.3 +/- 0.7 kPa, P < 0.01). In a subgroup of 33 patients re-evaluated after six months, individual changes in IVC and VE/CO2peak, but not in MIP, correlated to changes in VO2peak (r = 0.69 and r = 0.72 respectively; P < 0.01). In CHF, exercise limitation is associated with reversible lung restriction and inefficient ventilation at rest and during exercise. Patients with severe CHF have a significant reduction in MIP, a finding that is associated with poor outcome.
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Kreuzer J, Fei J, Werle M, Kübler W, Viedt C. Differential spatial distribution of activated MAP-kinases in smooth muscle cells after endothelin-1 stimulation: No nuclear translocation of ERK. Atherosclerosis 2000. [DOI: 10.1016/s0021-9150(00)81330-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Kreuzer J, Kübler W. Medical progress and rationing of cardiological services. ZEITSCHRIFT FUR KARDIOLOGIE 2000; 89 Suppl 4:IV61-7. [PMID: 10810778 DOI: 10.1007/s003920070064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Due to the financial restrictions imposed on all national health services, the problem of allocating medical resources has gained new economical and political dimensions. Although each patient expects optimal treatment, the rationing of medical services make it increasingly difficult to provide the most adequate therapy. Health politicians and medical doctors have all advocated that health expenditures can be reduced by effective prevention of coronary heart disease, one of the main cost factors for all health services. Due to the introduction of statins, primary and secondary prevention of coronary heart disease can now be accomplished effectively. However, such treatment does not induce cost reduction, but rather an increase in costs. This applies predominantly to primary prevention. Treatment of all who would benefit from lipid lowering by statins would be prohibitively expensive for all national health care systems.
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Zugck C, Krüger C, Dürr S, Gerber SH, Haunstetter A, Hornig K, Kübler W, Haass M. Is the 6-minute walk test a reliable substitute for peak oxygen uptake in patients with dilated cardiomyopathy? Eur Heart J 2000; 21:540-9. [PMID: 10775009 DOI: 10.1053/euhj.1999.1861] [Citation(s) in RCA: 146] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
AIMS The 6-min walk test may serve as a more simple clinical tool to assess functional capacity in congestive heart failure than determination of peak oxygen uptake by cardiopulmonary exercise testing. The purpose of the study was to prospectively examine whether the distance ambulated during a 6-min walk test (i) correlates with peak oxygen uptake, (ii) allows peak oxygen uptake to be predicted, and (iii) provides prognostic information similar to peak oxygen uptake in patients with dilated cardiomyopathy and left ventricular ejection fraction < or = 35%. METHODS AND RESULTS In 113 patients (age: 54+/-12 years, NYHA: 2.2+/-0.8) with dilated cardiomyopathy (left ventricular ejection fraction 19+/-7%) a 6-min walk test and cardiopulmonary exercise testing were performed. The 6-min walk test and peak oxygen uptake were closely correlated at the initial visit (r=0.68, n=113), as well as after 263+/-114 (r=0.71, n=28) and 381+/-170 days (r=0.74, n=14). During serial exercise testing the 6-min walk test allowed peak oxygen uptake to be reliably predicted (r=0.76 between calculated and real peak oxygen uptake). After 528+/-234 days, 42 patients were hospitalized due to worsening heart failure and/or died from cardiovascular causes. Compared to clinically stable patients, these 42 patients walked a shorter distance (423+/-104 vs 501+/-95 m, P<0.001) and had a lower peak oxygen uptake (12.7+/-4.0 vs 17.4 + 5.6 ml x min(-1) x kg(-1), P<0.001). By univariate analysis the 6-min walk test outperformed other prognostic parameters such as left ventricular ejection fraction, cardiac index and plasma norepinephrine concentration and conferred a prognostic power similar to peak oxygen uptake. This predictive value could be further improved in a multivariate model, by combining the 6-min walk test with independent variables, such as left ventricular ejection fraction or cardiac index. CONCLUSION The 6-min walk test correlated with peak oxygen uptake when tested serially over the course of the disease. Although both tests define two distinct domains of functional capacity, the 6-min walk test provides prognostic information very similar to peak oxygen uptake in congestive heart failure patients with dilated cardiomyopathy.
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Viedt C, Soto U, Krieger-Brauer HI, Fei J, Elsing C, Kübler W, Kreuzer J. Differential activation of mitogen-activated protein kinases in smooth muscle cells by angiotensin II: involvement of p22phox and reactive oxygen species. Arterioscler Thromb Vasc Biol 2000; 20:940-8. [PMID: 10764657 DOI: 10.1161/01.atv.20.4.940] [Citation(s) in RCA: 146] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The atherogenic effect of the renin-angiotensin system can be explained, in part, by the influence of its effector, angiotensin II (Ang II), on vascular smooth muscle cell (VSMC) growth. There is evidence that reactive oxygen species (ROS) play a role in the atherogenesis and activation of mitogen-activating protein (MAP) kinases, which are involved in proliferation and differentiation. The study was performed to further characterize the role of ROS in Ang II-mediated MAP kinase activation and the regulation of the transcription factor activator protein-1 (AP-1). Rat VSMCs were stimulated with Ang II. The activities of MAP kinases were assessed by Western blot analysis or by immunocomplex kinase assay. AP-1 binding was determined by using an electrophoretic mobility shift assay. Rat VSMCs were treated with Ang II-activated MAP kinases, extracellular signal-regulated kinase (ERK), c-Jun amino terminal kinase (JNK), p38 MAP kinase (p38 MAPK), and their downstream effector, AP-1. Interestingly, only the activation of ERK1/2, but not JNK or p38 MAPK, was tyrosine kinase, protein kinase C, and MEK1/2 dependent. Ang II also induced the rapid formation of ROS, which could be inhibited by a specific antibody as well as by antisense against the p22phox subunit of the NAD(P)H oxidase. JNK and p38 MAPK, but not ERK, activation was inhibited by an inhibitor of NAD(P)H oxidase. Antisense against p22phox also solely inhibited p38 MAPK but did not affect ERK. The results indicate that in VSMCs, Ang II activates MAP kinases and AP-1 through different pathways; the results further suggest that ROS, generated by p22phox, mediate Ang II-induced JNK and p38 MAPK activation, which may contribute to the pathogenesis of atherosclerosis.
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Senges JC, Sterns LD, Freigang KD, Bauer A, Becker R, Kübler W, Schoels W. Cesium chloride induced ventricular arrhythmias in dogs: three-dimensional activation patterns and their relation to the cesium dose applied. Basic Res Cardiol 2000; 95:152-62. [PMID: 10826508 DOI: 10.1007/s003950050177] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
INTRODUCTION Cesium chloride has widely been used in experimental models to produce various ventricular arrhythmias. The study was designed to evaluate whether type and mechanism of these arrhythmias are dose-dependent. METHODS In 7 dogs with acute AV-block, 60 pins containing 4 bipolar electrodes each were inserted into both ventricles to provide 240 endo-, epi- and midmyocardial recording sites. A computerized mapping system was used to determine three-dimensional activation patterns of ventricular arrhythmias induced by three injections of 1 mmol/kg cesium chloride at 20 minute intervals. RESULTS Out of all arrhythmias induced, 25 ventricular extrasystoles, 31 monomorphic and 47 polymorphic ventricular tachycardias were mapped. Nonsustained ventricular tachycardias were readily inducible by a single bolus of cesium chloride, whereas sustained episodes required repetitive injections (1.45 +/- 0.61 vs. 2.61 +/- 0.57 doses, p < 0.05). Polymorphic tachycardias were observed more commonly than monomorphic tachycardias (87 vs. 31). Initiation and maintenance of cesium induced arrhythmias were exclusively based on focal mechanisms originating from the subendocardium, irrespective of morphology and dosage. All monomorphic arrhythmias were caused by repetitive firing of single immobile foci located in either the right or the left ventricle. Bi- and multifocal mechanisms, however, were found to underlie the polymorphic episodes. CONCLUSIONS Although there is a dose-dependence as to the sustenance of mono- or polymorphic tachycardias, this does not reflect on the three-dimensional activation pattern of cesium induced arrhythmias, which are due to mono- or multifocal activation originating from the subendocardium.
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Browatzki M, Schmidt J, Kübler W, Kranzhöfer R. Endothelin-1 induces interleukin-6 release via activation of the transcription factor NF-kappaB in human vascular smooth muscle cells. Basic Res Cardiol 2000; 95:98-105. [PMID: 10826501 DOI: 10.1007/s003950050170] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The potent vasoconstrictor peptide endothelin-1 (ET-1) has been implicated in the pathophysiology of atherosclerosis and its complications. Since inflammation of the vessel wall is a hallmark of atherosclerosis, the purpose of the present study was to investigate the influence of ET-1 on cytokine production in human vascular smooth muscle cells (SMC) as a marker of inflammatory cell activation. ET-1 (100 pM - 1 microM) stimulated interleukin-6 (IL-6) secretion from human vascular SMC in a concentration-dependent manner. The ET-A-receptor antagonist BQ-123 (10 microM), but not the ET-B-receptor antagonist BQ-788, inhibited IL-6 release. ET-1 also transiently increased IL-6 mRNA compatible with regulation of IL-6 release at the pretranslational level. Electrophoretic mobility shift assays demonstrated time- and concentration-dependent activation of the proinflammatory transcription factor nuclear factor-kappaB (NF-kappaB) in ET-1-stimulated human vascular SMC. A decoy oligodeoxynucleotide bearing the NF-kappaB binding site inhibited ET-1-stimulated IL-6 release to a great extent suggesting that this transcription factor plays a key role for cytokine production elicited by ET-1. Moreover, the antioxidant pyrrolidine dithiocarbamate (10 microM) inhibited ET-1-induced IL-6 release indicating involvement of reactive oxygen species in ET-1 signaling. ET-1-stimulated IL-6 secretion was also suppressed by diphenylene iodonium (40 microM), an inhibitor of flavon-containing enzymes such as NADH/NADPH oxidase. The results demonstrate the ability of ET-1 to induce an inflammatory response in human vascular SMC. These observations may contribute to a better understanding of the role of ET-1 in inflammatory activation of the vessel wall during atherogenesis.
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Bea F, Bär H, Watson L, Blessing E, Kübler W, Kreuzer J, Jahn L. Cardiac alpha-actin in smooth muscle cells: detection in umbilical cord vessels and in atherosclerotic lesions. Basic Res Cardiol 2000; 95:106-13. [PMID: 10826502 DOI: 10.1007/s003950050171] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phenotypic modulation of smooth muscle cells (SMC) is a key event during the development of atherosclerotic and restenotic lesions. During this process, the composition of the cytoskeleton is substantially altered, with changes predominantly in actin expression reflecting a shift from smooth muscle alpha-actin to the non-muscle beta-isoform. We now demonstrate that yet another actin isoform, cardiac alpha-actin, is synthesized, de novo, in SMC of various atherosclerotic lesions. Using a highly specific monoclonal antibody against cardiac alpha-actin, we analyzed and compared the accumulation of this actin isoform in diverse SMC by immunofluorescence microscopy and immunoblotting. As expected, cardiac alpha-actin was present in human myocardium but not in healthy SMC of adult aorta, coronary arteries, trabeculae of the spleen, colon, stomach or skeletal muscle. Interestingly, the presence of cardiac alpha-actin was detected in umbilical cord vessels, human myometrium, in atherosclerotic coronary lesions and atherosclerotic lesions from peripheral vascular disease. The distribution of cardiac alpha-actin often paralleled that of cytokeratins 8 and 18, intermediate filament proteins typically found in dedifferentiated SMC. Taken together, the data presented here illustrate the expression of cardiac alpha-actin to be limited to either fetal vessels or those vessels or tissue having suffered damage or atrophy, outside its 'native' environment in the heart. The demonstration of cardiac alpha-actin in SMC of umbilical cord vessels and in atherosclerotic lesions but not in apparently healthy vessels supports the notion that SMC in atherosclerotic lesions exhibit a dedifferentiated phenotype.
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Grünig E, Mereles D, Hildebrandt W, Swenson ER, Kübler W, Kuecherer H, Bärtsch P. Stress Doppler echocardiography for identification of susceptibility to high altitude pulmonary edema. J Am Coll Cardiol 2000; 35:980-7. [PMID: 10732898 DOI: 10.1016/s0735-1097(99)00633-6] [Citation(s) in RCA: 174] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVE This prospective single-blinded study was performed to quantitate noninvasive pulmonary artery systolic pressure (PASP) responses to prolonged acute hypoxia and normoxic exercise. BACKGROUND Hypoxia-induced excessive rise in pulmonary artery pressure is a key factor in high-altitude pulmonary edema (HAPE). We hypothesized that subjects susceptible to HAPE (HAPE-S) have increased pulmonary artery pressure response not only to hypoxia but also to exercise. METHODS PASP was estimated at 45, 90 and 240 min of hypoxia (FiO2 = 12%) and during supine bicycle exercise in normoxia using Doppler-echocardiography in nine HAPE-S and in 11 control subjects. RESULTS In the control group, mean PASP increased from 26+/-2 to 37+/-4 mm Hg (deltaPASP 10.3+/-2 mm Hg) after 90 min of hypoxia and from 27+/-4 to 36+/-3 mm Hg (deltaPASP 8+/-2 mm Hg) during exercise. In contrast, all HAPE-S subjects revealed significantly greater increases (p = 0.002 vs. controls) in mean PASP both during hypoxia (from 28+/-4 to 57+/-10 mm Hg, deltaPASP 28.7+/-6 mm Hg) and during exercise (from 28+/-4 to 55+/-11 mm Hg, deltaPASP 27+/-8 mm Hg) than did control subjects. Stress echocardiography allowed discrimination between groups without overlap using a cut off PASP value of 45 mm Hg at work rates less than 150 W. CONCLUSIONS These data indicate that HAPE-S subjects may have abnormal pulmonary vascular responses not only to hypoxia but also to supine bicycle exercise under normoxic conditions. Thus, Doppler echocardiography during supine bicycle exercise or after 90 min of hypoxia may be useful noninvasive screening methods to identify subjects susceptible to HAPE.
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Peter K, Graeber J, Kipriyanov S, Zewe-Welschof M, Runge MS, Kübler W, Little M, Bode C. Construction and functional evaluation of a single-chain antibody fusion protein with fibrin targeting and thrombin inhibition after activation by factor Xa. Circulation 2000; 101:1158-64. [PMID: 10715263 DOI: 10.1161/01.cir.101.10.1158] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Recombinant technology was used to produce a new anticoagulant that is preferentially localized and active at the site of the clot. METHODS AND RESULTS The variable regions of the heavy and light chains of a fibrin-specific antibody were amplified by polymerase chain reaction (PCR) with hybridoma cDNA. To obtain a functional single-chain antibody (scFv), a linker region consisting of (Gly(4)Ser)(3) was introduced by overlap PCR. After the scFv clones were ligated with DNA encoding the pIII protein of the M13 phage, high-affinity clones were selected by 10 rounds of panning on the Bbeta15-22 peptide of fibrin (beta-peptide). Hirudin was genetically fused to the C-terminus of the variable region of the light chain. To release the functionally essential N-terminus of hirudin at the site of a blood clot, a factor Xa recognition site was introduced between scFv(59D8) and hirudin. The fusion protein was characterized by its size on SDS-PAGE (36 kDa), by Western blotting, by its cleavage into a 29-kDa (single chain alone) and 7-kDa (hirudin) fragment, by its binding to beta-peptide, and by thrombin inhibition after Xa cleavage. Finally, the fusion protein inhibited appositional growth of whole blood clots in vitro more efficiently than native hirudin. CONCLUSIONS A fusion protein was constructed that binds to a fibrin-specific epitope and inhibits thrombin after its activation by factor Xa. This recombinant anticoagulant effectively inhibits appositional clot growth in vitro. Its efficient and fast production at low cost should facilitate a large-scale evaluation to determine whether an effective localized antithrombin activity can be achieved without systemic bleeding complications.
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