bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tissue plasminogen activator and neuroserpin are widely expressed in the human central nervous system
Authors: Kulla Andres , Simisker Aadu , Sirén Vappu , Lawrence Daniel , Asser Toomas , Vaheri Antti , Teesalu Tambet 
Published: July 2004

SummaryTissue plasminogen activator (tPA) is increasingly recognized to play important roles in various physiological and pathological processes in the central nervous system (CNS). Much of the data on the involvement of plasminogen activators in neurophysiology and -pathology have been derived from studies on experimental animals. We have now performed a systematic characterization of the expression of tPA and its inhibitor, neuroserpin, in normal human CNS. Brain and spinal cord samples from 30-36 anatomic locations covering all major brain regions were collected at 9 autopsies of donors with no neurological disease. Tissues were embedded in paraffin and tissue arrays were constructed. In two cases parallel samples were snap-frozen for biochemical analysis. Expression and activity profiling of tPA and neuroserpin were performed by immunohistochemistry, in situ hybridization, immunocapture and zymography assays. In the adult CNS, tPA was expressed at the mRNA and protein levels in many types of neurons, in particular in thalamus, cortex of cerebellum, pontine nuclei, neocortex, limbic system, and medulla oblongata. Interestingly, tPA was often co-expressed with its CNS inhibitor, neuroserpin. Despite overlapping expression of tPA and neuroserpin, zymography and immunocapture assays demonstrated that human neural tissue is a rich source of active tPA. Our analysis documents a detailed map of expression of tPA and its inhibitor in the human CNS and is compatible with the view that tPA is a key player in CNS physiology and pathology.
Activation of fibrinolysis in the pericardial cavity after cardiopulmonary bypass
Authors: Ismail Mohamed , Kalmar Peter , von Knobelsdorff Georg , Marx Guy , Khalil Philipe 
Published: July 2004

SummaryAprotinin is frequently administered systemically in patients undergoing cardiopulmonary bypass to preserve platelet function and ameliorate excessive activation of fibrinolysis. More recently, aprotinin topically applied in the pericardial cavity was also found to improve postoperative blood loss. However, platelet activation was not reduced locally during surgery. Hence, we investigated in the present prospective, in a randomized double-blind trial, the intra- and early postoperative state of systemic and local fibrinolytic activity, and whether topically administered aprotinin acts as an antifibrinolytic and therefore improves local hemostasis. Patients undergoing elective coronary artery bypass grafting were divided in two groups containing 22 patients each. Both, group I and II patients received highdose aprotinin (6.0 × 106 kallikrein inhibitor units (KIU)) systemically. Before resuming extracorporeal circulation (ECC), either 1.0 × 106 KIU aprotinin (group I) or vehicle solution (group II) was applied into the pericardial cavity. Plasminogen, α2-antiplasmin, plasmin-α2-antiplasmin complex, plasminogenactivator-inhibitor type-1 and D-dimers were measured in the pericardial cavity and systemic circulation immediately before resuming extracorporeal circulation (ECC), and at 1 h and 4 h postoperatively. The local fibrinolytic activity was found to significantly exceed that measured in the systemic circulation over time, whether ot not they received aprotinin into the thoracic wound surface. Furthermore, evidence was provided that topically applied aprotinin reduces not only the local fibrinolytic activity but also the postoperative blood loss significantly by 33% which demonstrates the clinical relevance. The local activation of fibrinolysis seems to play an important role in blood loss after cardiopulmonary bypass. Therefore in fibrinolysis and blood coagulation the surgeon should not only consider what happens in the systemic circulation but also on a local level.
Recombinant urokinase for restoration of patency in occluded central venous access devices
Authors: Deitcher Steven , Mullane Kathleen , Jaff Michael , Firszt Carolyn , Schulz Gregory , Schuerr Debra , Schwartz Lewis , Mouginis Tamyra , Barton R. , Haire William 
Published: July 2004

SummaryThe interval occlusion of central venous access devices (CVADs) remains a significant clinical problem, often requiring re-intervention for catheter exchange or replacement.The purpose of this Phase 3, multi-center, double-blinded study was to test the hypothesis that instillation of recombinant urokinase (r-UK) 5000 IU/ml is superior to placebo in restoring total catheter patency to an unselected cohort of occluded CVADs. After obtaining informed consent, adult and pediatric patients with occluded, non-hemodialysis CVADs of any duration or type were randomized (2 : 1) to receive either r-UK 5000 IU/ml or placebo instilled into all occluded lumens of their catheter. Catheter function was assessed at 5, 15 and 30 min after the first instillation. If the catheter remained occluded after 30 min, a second dose was instilled with repeat assessments at 5, 15 and 30 min.The primary efficacy variable was the restoration of catheter function to all treated lumens (i.e., total catheter patency) after one or two instillations. Catheters that were not successfully recanalized after two instillations were allowed to receive up to two instillations of open-label r-UK administered in the same manner.The primary safety variable was the occurrence of hemorrhagic and non-hemorrhagic events within 72 hr after instillation. A total of 180 patients were enrolled at 43 sites in the United States and Canada. Most patients were adults, although 20% were ≤18 years of age. CVAD types included totally implanted subcutaneous ports (45%), PICC lines (26%), non-tunneled percutaneous catheters (18%), and tunneled percutaneous catheters (10%). All CVADs were occluded by virtue of their inability to withdraw blood (withdrawal occlusion). Additionally, 32% of catheters were completely dysfunctional as blood could not be withdrawn and fluids could not be infused (total occlusion). Analysis of the results showed that r-UK was significantly better than placebo in restoring catheter function (54% versus 30%, p = 0.002). There were no major hemorrhagic events within 72 hr after up to four r-UK instillations, and the incidence of non-hemorrhagic events was similar among the r-UK and placebo groups. In conclusion, r-UK is superior to placebo in restoring total catheter patency to occluded CVADs. In patients with occluded CVADs, intra-catheter thrombolysis can restore patency and may obviate the need for catheter replacement.
Neutrophil function in the healing wound: adding insult to injury?
Authors: Dovi Julia , Szpaderska Anna , DiPietro Luisa 
Published: July 2004

SummaryCells of the innate immune system, including neutrophils and macrophages, are a highly visible component of normal wound healing in adult mammals. The role of inflammatory cells in the healing wound has been widely investigated, and evidence for both positive and negative influences exists. Several recent investigations support the emerging paradigm that robust inflammation is detrimental to wound closure. This developing information suggests that the functional role of inflammatory cells in wound healing must be reevaluated.
Genetic and environmental influences on the fibrinolytic system: a twin study
Authors: Victor Anja , Adams Petra , Erbes Hilde , Hafner Gerd , Lackner Karl , Hoehler Thomas , Peetz Dirk 
Published: July 2004

SummaryThe determination of heritability is a key issue to assess the predictive power of polymorphisms for disease in clinical studies. The aim of this study was to determine the heritability of proteins and activation markers of the fibrinolytic system in a large cohort of healthy twins. Heritability was calculated as 0.76 for thrombin activatable fibrinolysis inhibitor (TAFI), 0.44 for plasminogen activator inhibitor-1 (PAI-1), and 0.43 for tissue plasminogen activator. No significant genetic influence was observed for α2-antiplasmin-plasmin-complex and D-dimer. Heritability explained by single gene polymorphisms was 25.2% for TAFI 505G>A, 31.5% for 1542C>G, and 50.0% for combination of both. The influence on TAFI levels of 1542C>G (CC→GG, median: −280.5%) was considerably stronger than that of 505G>A (GG→AA, median: +49.3%) and in both cases there seems to be a dose-response relationship. Significant environmental influences on TAFI levels were observed for combined interaction terms (age*sex and bmi*sex). The PAI-1 4G/5G polymorphism explained 56.4% of the calculated heritability. The genetic variables accounting for the 43% heritability of tPA remain unknown. Our data show that the production of several key components of the fibrinolytic system is strongly genetically determined. This genetic influence is accounted for in large part but not completely by a limited number of polymorphisms within the respective genes associated with plasma levels of the gene products.
Characterization of plasminogen variants in healthy subjects and plasminogen mutants in patients with inherited plasminogen deficiency by isoelectric focusing gel electrophoresis
Authors: Tefs Katrin , Georgieva Maria , Seregard Stefan , Tait Campbell , Luchtman-Jones Lori , Ziegler Maike , Hügle Boris , Schuster Volker 
Published: July 2004

SummaryPlasmin(ogen) plays an important role in fibrinolysis and wound healing. Severe hypoplasminogenemia has recently been linked to ligneous conjunctivitis. Plasminogen (plg) is known as a polymorphic protein and most of these variants have been identified using isoelectric focusing (IEF) gel electrophoresis. Here, we studied common plg variants from healthy subjects and plg mutants from three patients with hypoplasminogenemia and three subjects with dysplasminogenemia by molecular genetic analysis and IEF. Analysis of 24 healthy subjects showed that subjects with the most common IEF plg phenotype A (n = 12) were homozygous for aspartate at position 453 (453D), while both subjects with IEF plg phenotype B were homozygous for asparagine at this position (453N). Subjects with IEF plg phenotype AB (n = 10) were compound-heterozygous for 453D/453N. Three patients with severe hypoplasminogenemia and different plg gene mutations exhibited characteristic “abnormal” IEF band patterns when compared with IEF plg phenotypes A and B. In all heterozygous family members the observed IEF plg phenotype was derived from the wild type plg molecule only, probably due to low concentration of the mutant plg molecule in plasma. In contrast, in three unrelated subjects with heterozygous dysplasminogenemia an equal “mixture” of wild type and mutant plg was found by IEF analysis. In conclusion, plg phenotyping by IEF in combination with molecular analysis of the plg gene seems to be a useful method for characterization of plg variants and mutants.
Platelet hyperreactivity in hemodialysis patients with frequently occluded vascular access
Authors: Chou Kang-Ju , Jan Chung-Ren , Lee Po-Tsang , Chen Chien-Liang , Chung Hsiao-Min , Hwang Yueh-Yen , Chou Jing-Dung , Fang Hua-Chang 
Published: July 2004

SummaryIt is known that thrombosis is a leading cause of vascular access failure and that the formation of thrombus requires platelets. The activation of platelets induces the increase in intracellular Ca2+ levels ([Ca2+]i) leading to aggregation and thrombosis. We compared the platelet [Ca2+]i
before and after stimulation between the patients with and without easily occluded vascular access. Our study included two groups of hemodialysis patients. Group 1 consisted of 21 patients who had received chronic hemodialysis therapy for more than 6 months. They had had more than three events (including three) of vascular access failures during the past year. Group 2 consisted of 21 hemodialysis patients with age, sex, and diabetes mellitus matched who had never suffered from any event of vascular access failure. We measured the basal and stimulated platelet [Ca2+]i
after stimulation with 1 U/ml thrombin, 1 µM arachidonic acid, 1 µM platelet activation factor (PAF), and 10 µM adenosine diphosphate (ADP), respectively. Our results showed that in Ca2+-containing media, there was no significant differences in the basal [Ca2+]i
, but the maximal increases of [Ca2+]i
of platelets were higher (p <0.05) in group 1 than in group 2 after stimulating with PAF and ADP, but not with thrombin and arachidonic acid. We concluded that the causes for the susceptibility of some hemodialysis patients to vascular access occlusion were multifactorial. In addition to previously reported plasma factors, there was a subgroup of patients who showed greater elevations of agonists stimulated platelet intracellular calcium levels.
Variable extent of clopidogrel responsiveness in patients after coronary stenting
Authors: Schnurr Axel , Bonz Andreas , Porsche Christian , Obergfell Achim , Lengenfelder Björn , Walter Ulrich , Eigenthaler Martin , Grossmann Ralf , Sokolova Olga 
Published: July 2004

SummaryClopidogrel is an effective and specific inhibitor of ADP-induced platelet aggregation. After metabolic activation, the active clopidogrel metabolite irreversibly impairs the human platelet P2Y12 ADP receptor. Gialpha-protein activation and inhibition of vasodilator-stimulated phosphoprotein (VASP) phosphorylation are two key elements of the P2Y12 receptor pathway suitable for quantitation of clopidogrel effects. So far, only limited data exist about a diminished responsiveness to clopidogrel and underlying possible mechanisms. We investigated clopidogrel effects in 57 patients after percutaneous coronary intervention and stent implantation by flow cytometry for the analysis of intracellular VASP phosphorylation. Patients were treated with a 300 mg clopidogrel loading dose, followed by 75 mg/day clopidogrel in combination with 100 mg/day aspirin. Samples were drawn after a median of 5 days of clopidogrel treatment. Considerable differences in the responsiveness to clopidogrel could be observed and it was shown that 17.5% (10/57) of the patients revealed an inadequate responsiveness to clopidogrel despite continuation of clopidogrel intake. Comparable amounts of Gialpha and VASP were found in two clopidogrel low-responding patients as well as in two responding patients. To exclude a molecular defect of P2Y12 ADP receptor, the P2Y12 receptor gene of eight clopidogrel treated patients (seven patients with inadequate responsiveness, one responder) was sequenced. We only found a single silent mutation in exon 2 at position 1828 (GA). We suggest that individual differences in clopidogrel metabolization could cause relevant variations in clopidogrel responsiveness despite the use of a 300 mg clopidogrel loading dose.
A comparative study of amyloid-beta (1-42) as a cofactor for plasminogen activation by vampire bat plasminogen activator and recombinant human tissue-type plasminogen activator
Authors: Schleuning Wolf-Dieter , Kruithof Egbert 
Published: July 2004

SummaryThe activity of both human tissue-type plasminogen activator (t-PA) and the PA from the saliva of the vampire bat, Desmodus rotundus, (DSPA) is critically dependent on the presence of a cofactor. The most efficient cofactor for both PAs is fibrin, but fibrinogen and amyloid beta peptides also have cofactor activities for human t-PA. Compared to t-PA, DSPA has a more stringent requirement for fibrin as a cofactor. The present study was undertaken to compare cofactor activities of amyloid beta 1-42 (Aβ1-42) for plasminogen activation by DSPA-α1 or by t-PA. The two PAs were incubated with different concentrations of glu-plasminogen, a chromogenic substrate for plasmin and 100 µg mL-1 of Aβ1-42, fibrinogen or fibrin as cofactor. Using the kinetic parameters directly determined from the chromogenic substrate conversion curves, we derived the relative efficacies of DSPA or t-PA in the presence of cofactor at the physiological plasminogen concentration of 2 µM. In the presence of fibrin, the activity of DSPA was comparable to that of t-PA and 23,270-fold higher than its activity without cofactor, whereas fibrin induced only a 248-fold increase in t-PA activity. The activity of DSPA with Aβ1-42 or fibrinogen as cofactor was 485-fold lower than its activity in the presence of fibrin, while for t-PA this difference was only 26-fold. The much lower activity of DSPA as compared to t-PA with Aβ1-42 or fibrinogen might lead to fewer side effects when used for the thrombolytic therapy of stroke.
Expression of therapeutic levels of factor VIII in hemophilia A mice using a novel adeno/adeno-associated hybrid virus
Authors: Gnatenko Dmitri , Wu Yong , Jesty Jolyon , Damon Andrea , Hearing Patrick , Bahou Wadie 
Published: July 2004

SummaryWe have generated an E1a/E1b/E3-deleted adeno/adeno-associated (Ad/AAV) hybrid virus driven by a small nuclear RNA (pHU1-1) promoter for expression of a B domain-deleted (Thr761-Asn1639) factor VIII transgene (FVIIIΔ761-1639). Productive replication of Ad/AAV/FVIIIΔ761-1639 in AAV repexpressing cells resulted in generation of monomeric and dimeric mini-adenoviral (mAd) replicative forms that retained the AAV integration elements (mAd/FVIIIΔ761-1639). In vitro studies using Ad/AAV/FVIIIΔ761-1639 generated ∼2-logs greater FVIII activity than mAd/FVIIIΔ761-1639. To determine its capacity for in vivo excision and/or genomic integration, Ad/AAV/FVIIIΔ761-1639 was injected by tail vein into three groups of hemophilia A mice (2 X 1011 vp [n = 3]; 4 X 1011 vp [n = 3]; 8 X 1011 vp [n = 3]), with clear concentration-dependent increase in FVIII activity (range 160-510 mU/ml; plasma activity 16% – 51% of normal). Peak activity was seen by Day (D) 5, with slow return to baseline by D28 (0.1 – 0.9% activity); in only 3/9 mice was loss of FVIII activity associated with development of anti-FVIII antibodies. Quantitative-PCR using genomic DNA isolated from D28 liver, spleen, heart, lungs, and kidney demonstrated the highest concentration in liver (∼10 genomes/ cell), with little to no organ toxicity at early (D5 or 6) or late (D28) post-infusion time points. There was no evidence for spontaneous transgene excision or genomic integration in vivo as evaluated by quantitative PCR and genomic blotting. These data establish (i) the feasibility and applicability of developing high-titer Ad/AAV hybrid viruses for FVIII delivery using a small cellular promoter, (ii) the potential utility of this virus for generation of “gutted” monomeric and dimeric mAD/FVIII retaining AAV integration elements, and (iii) that the development of strategies for regulated Rep68/78 co-expression may provide a novel approach for excision, integration, and long-term FVIII transgene expression.
A marriage of enhancement: fibrinolysis and conjunctive therapy
Authors: Welsh Robert , Armstrong Paul 
Published: July 2004

SummaryPharmacologic reperfusion of patients with acute ST segment elevation myocardial infarction is designed to achieve prompt high-quality reperfusion, prevent recurrent ischemia and reinfarction, maintain long-term patency, and to enhance patient survival and quality of life. Because monotherapy with fibrinolytics is by itself unable to achieve all of these objectives, antithrombotic, anti-platelet, and other novel agents are required. We discuss herein the role of unfractionated and enoxaparin, the potential added value of direct thrombin inhibitors, and the importance of aspirin. Despite the promise of glycoprotein IIb/IIIa inhibitors, risks associated with intracranial hemorrhage in the elderly have led to restraint in their application to broad populations. Facilitation of urgent percutaneous coronary intervention with combination reduced-dose fibrinolytic and glycoprotein IIb/IIIa inhibitors remains a promising potential future path. The future is likely to emphasize greater application of the already effective therapies at our disposal and the development of novel anti-platelet and anti-thrombin agents as well as those directed toward inflammation.
Point of care monitoring of oral anticoagulant therapy in children: comparison of CoaguChek Plus and Thrombotest methods with venous international normalised ratio
Authors: Ignjatovic Vera , Barnes Chris , Newall Fiona , Hamilton Simone , Burgess Janet , Monagle Paul 
Published: July 2004

SummaryThis paper reports the outcome of a research protocol aimed at optimising warfarin monitoring in a tertiary pediatric centre. The Thrombotest™ INR was the standard monitoring test employed to manage oral anticoagulant therapy in children at the Royal Children’s Hospital (RCH), Melbourne. This study compares the results of this standard method to the novel CoaguChek® INR monitor and the “gold standard” technique of venous INR sampling. The objectives were to determine 1) if point-of-care techniques of measuring the INR (Thrombotest and CoaguChek) are accurate and reliable compared to INR results obtained from venous sampling, processed in an accredited laboratory, and 2) if INR results generated by POC devices can be safely used to manage oral anticoagulant therapy in children. 18 children (10 females and 8 males) participated in the study. Ages ranged from 9 months to 21 years (Mean 11.9 years; SD 5.03 years). The agreement between CoaguChek and venous INR measurements (r = 0.885) was shown to be higher compared to Thrombotest and venous INR (r = 0.700). Compared to the venous INR, values obtained with Coaguchek and Thrombotest crossed into or out of the therapeutic range in 25% and 36% of cases respectively. In 88% of the CoaguChek cases and 57% Thrombotest cases, the difference from the venous result was less than 0.5. The CoaguChek method of INR monitoring is a more accurate and reliable method compared to Thrombotest, in the pediatric population tested, and can be safely used to manage oral anticoagulant therapy in children.
Pharmacokinetics of clopidogrel after administration of a high loading dose
Authors: Kastrati Adnan , Harlfinger Steffi , Gorchakova Olga , Lazar Andreas , von Beckerath Nicolas , Schömig Albert , Schömig Edgar , Taubert Dirk 
Published: July 2004

SummaryThe adenosine diphosphate (ADP) receptor P2Y12 blocking agent clopidogrel is clinically proven to be efficient in preventing thrombotic events. However, its therapeutic value is limited by an, as yet poorly explained, interindividual heterogeneity in platelet inhibition. To evaluate possible pharmacokinetic determinants of this response variability, we developed a sensitive and specific liquid chromatography tandem mass spectrometry (LC-MS/MS) assay for quantification of unmodified inactive clopidogrel, its inactive carboxyl metabolite, and its active thiol metabolite in plasma. Analyte concentrations and platelet aggregation were assessed in ten healthy volunteers receiving an oral load of 600 mg clopidogrel. Subjects showed marked inter-individual differences in maximal platelet inhibition and in plasma pharmacokinetics. Univariate regression revealed linear correlations between maximal antiplatelet effect and peak plasma concentrations (cmax) of unchanged clopidogrel (r=0.76; p=0.01), of the carboxyl metabolite (r=0.70; p=0.03), and of the thiol metabolite (r=0.73; p=0.02), as well as linear correlations between cmax values of clopidogrel and its metabolites. This indicates that the response variability is predominantly caused by individual differences in clopidogrel absorption and that other factors, such as ADP receptor reactivity or differences in bioactivation of clopidogrel, do not play a major role.