bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adverse Effect of Heparin on Antithrombin Action during Endotoxemia: Microhemodynamic and Cellular Mechanisms
Authors: Vollmar Brigitte , Laschke Matthias , Inthorn Dietrich , Kaneider Nicole , Dunzendorfer Stefan , Wiedermann Christian , Römisch Jürgen , Schildberg Friedrich , Menger Michael , Hoffmann Johannes 
Published: March 2018

SummaryA recent clinical sepsis trial reported a significant reduction in 90-day mortality by antithrombin (AT) exclusively in the subgroup of patients without simultaneous heparin prophylaxis. Patients additionally receiving heparin did not benefit from AT treatment. Herein, we studied the microhemodynamic and cellular mechanisms of this adverse effect of heparin on AT actions by the use of intravital microscopy and granulocyte culturing. In Syrian golden hamsters normotensive endotoxemia was induced by 2 mg/kg endotoxin (LPS, E. coli) i.v. In a first group of animals, AT (AT, 250 IU/kg i.v., n = 6) was given 5 min before LPS administration. A second group of animals (Heparin+AT, n = 5) received AT (250 IU/kg i.v.) combined with unfractionated heparin (sodium heparin, 100 IU/kg/24 h, i.v.). Additional animals (LMWH+AT, n = 5) received AT (250 IU/kg i.v.) combined with LMWH (nadroparin 47.5 IU anti-Xa/kg, s.c., 2 h before LPS). LPStreated animals, which received only saline, served as controls (control, n = 6). Using dorsal skinfold fold preparations, LPS-induced microvascular leukocyte-endothelial cell interaction (LE) and alteration of functional capillary density (FCD) were studied by intravital video fluorescence microscopy. In controls, LPS induced a massive increase in LE with a maximum at 8 h and an impressive decrease in FCD over a 24-hour period. Both LPS effects were effectively prevented by AT treatment (p <0.01), whereas Heparin+AT and LMWH+AT animals showed microcirculatory alterations comparable to that in controls. In additional in vitro chemotaxis assays, AT blocked neutrophil chemotaxis, an effect reversed by both unfractionated heparin and LMWH. Thus, our study elucidates a relevant in vivo and in vitro unfractionated heparin and LMWH adverse effect in the microcirculatory actions of AT during endotoxemia. These results indicate that heparin should be avoided to permit AT to modulate LPS-induced inflammatory responses.
A Collaborative Study to Establish the 3rd International Standard for Tissue Plasminogen Activator
Authors: Sands Dawn , Whitton Colin , Merton R. , Longstaff Colin 
Published: March 2018

SummaryAn international collaborative study was organised to replace the 2nd International Standard (IS) for tissue plasminogen activator (tPA). The 2nd IS for tPA (86/670) was used to calibrate the replacement Standard, which was selected from two candidate materials included in the collaborative study. Participants were provided with five sets of four samples (A, B, C, D) and asked to use sample A (2nd IS, 86/670, 850 IU/ml) to determine the activity of B (86/624, approximately 850 IU/ml), C and D (coded duplicates of the same material, 98/714 approximately 11000 IU/ml). A total of 14 laboratories returned results from Europe, USA, Japan and Australia, providing data from 60 independent assays. Four laboratories used a reference method based on a published monograph from the European Pharmacopoeia for Alteplase for Injection, 1998, and the remaining 10 used their own method. Fibrin was used as promoter of tPA activity by 12 out of the 14 laboratories, the remaining two used kits where fibrinogen fragments were the promoter. Data from this collaborative study and the previous study to establish the 2nd IS for tPA show that tPA from melanoma cells and recombinant tPA from CHO cells are both suitable materials as International Standards. It was agreed that sample C, D, recombinant tPA, 98/714, be established as the 3rd International Standard for tPA with a potency of 10000 IU per ampoule, calculated as the mean value from laboratories using fibrin as a promoter of tPA activity. The standard was established by WHO in November 2000.
Metalloproteases Cleave the Urokinase-Type Plasminogen Activator Receptor in the D1-D2 Linker Region and Expose Epitopes not Present in the intact Soluble Receptor
Authors: Andolfo Annapaola , English William , Resnati Massimo , Murphy Gillian , Blasi Francesco , Sidenius Nicolai 
Published: March 2018

SummaryProteolytic cleavage of the urokinase plasminogen activator receptor (uPA(R)) prevents the binding of uPA and vitronectin while generating biologically active uPAR fragments. We have recently shown that matrix metalloproteinase-12 (MMP-12) releases cellular uPAR-antigen from stimulated human micro-vascular endothelial cells providing a novel feedback mechanism between the plasminogen activation and MMP systems. We now show that MMP-12 and other MMPs directly and efficiently cleave uPAR at the Thr86||Tyr87 peptide bond located in the linker region connecting uPAR domains 1 and 2, releasing the major ligand binding domain 1 from the rest of the receptor. The possible biological importance of uPAR cleavage by MMPs is supported by the observation that also murine uPAR is cleaved by MMP-12 (at the Pro89||Gln90 peptide bond), despite the limited sequence homology between the linker regions. Using an antibody raised against the human uPAR linker region we show that this region of uPAR, which contains the chemotactic SRSRY epitope, is exposed upon MMP cleavage.
Protease-Activated Receptors Upregulate Cyclooxygenase-2 Expression in Human Endothelial Cells
Authors: Houliston Rebecca , Keogh Rosemary , Sugden David , Dudhia Jayesh , Carter Tom , Wheeler-Jones Caroline 
Published: March 2018

SummaryWe have previously shown that the serine protease thrombin and other G protein-coupled agonists acutely enhance synthesis and release of prostacyclin from human umbilical vein endothelial cells (HUVEC) through activation of cPLA2α. Here, we show that thrombin and other physiological endothelial cell agonists upregulate COX-2 induction in HUVEC. Thrombin treatment caused a rapid and sustained increase in prostacyclin (PGI2) synthesis from HUVEC. Thrombin and a selective protease-activated receptor-1 (PAR-1) peptide (TRAP) evoked doseand time-dependent increases in COX-2 protein expression which were equivalent to that induced by the proinflammatory cytokine IL-1α. Quantitative and real-time PCR analysis showed enhanced COX-2 mRNA expression in thrombinor TRAP-stimulated HUVEC whereas COX-1 expression was unaffected. A PAR-2 agonist peptide also induced COX-2 protein and mRNA expression with kinetics distinct from those of thrombin, and promoted PGI2 release. These results demonstrate that regulation of COX-2 induction is an important functional response of HUVEC to PAR activation and suggest that PARs promote sustained upregulation of prostanoid production in human endothelium.
Modulation of Fibrinolytic and Gelatinolytic Activity during Adipose Tissue Development in a Mouse Model of Nutritionally Induced Obesity
Authors: Maquoi Erik , Demeulemeester Diego , Van Hoef Berthe , Collen Désiré , Lijnen H. 
Published: March 2018

SummaryA nutritionally induced obesity model was used to investigate the modulation of fibrinolytic and gelatinolytic activity during the development of adipose tissue.Five week old male mice were fed a standard fat diet (SFD, 13% kcal as fat) or a high fat diet (HFD, 42% kcal as fat) for up to 15 weeks. The HFD resulted in body weights of 31 ± 0.9 g, 38 ± 2.0 g and 47 ± 1.9 g at 5, 10 and 15 weeks, respectively; corresponding values for mice on the SFD were 26 ± 0.6 g, 31 ± 0.9 g and 31 ± 1.2 g (all p < 0.001). The weight of the isolated subcutaneous (SC) or gonadal (GON) fat after 15 weeks of HFD was 1,870 ± 180 mg or 1,470 ± 160 mg, as compared to 250 ± 58 mg or 350 ± 71 mg for the SFD (p < 0.001). The HFD induced marked time-dependent hyperglycemia and elevated levels of triglycerides and total cholesterol. The HFD diet also induced a marked hypertrophy of the adipocytes as compared to the SFD, e.g. diameter of 83 ± 3.0 µm versus 52 ± 4.2 µm for GON adipocytes at 15 weeks (p < 0.005). Plasma plasminogen activator inhibitor-1 (PAI-1) levels were higher in mice on the HFD as compared to the SFD; they were comparable in extracts of SC or GON adipose tissue, whereas at different time points tissue-type (t-PA) and urokinase-type (u-PA) plasminogen activator activity was somewhat lower in the adipose tissues of mice on HFD. Gelatinolytic activity (mainly MMP-2) was detected in SC but not in GON adipose tissue of mice on SFD, and decreased on the HFD. In situ zymography on cryosections did not reveal different fibrinolytic activities in SC or GON adipose tissues of the HFD as compared to the SFD groups, whereas significantly lower gelatinolytic and higher caseinolytic activities were detected in SC and GON tissues of mice on the HFD (p ≤ 0.05). The fibrillar collagen content was lower in adipose tissue of mice on HFD. Thus, in this model time-dependent development of adipose tissue appears to be associated with modulation of proteolytic activity.
Platelet Activation and Blood Coagulation
Authors: Bevers Edouard , Lindhout Theo , Heemskerk Johan 
Published: March 2018

SummaryPlatelet activation and blood coagulation are complementary, mutually dependent processes in haemostasis and thrombosis. Platelets interact with several coagulation factors, while the coagulation product thrombin is a potent platelet-activating agonist. Activated platelets come in a procoagulant state after a prolonged elevation in cytosolic [Ca2+]i. Such platelets, e. g. when adhering to collagen via glycoprotein VI, expose phosphatidylserine (PS) at their outer surface and produce (PS-exposing) membrane blebs and microvesicles. Inhibition of aminophospholipid translocase and activation of phospholipid scramblase mediate the exposure of PS, whereas calpain-mediated protein cleavage leads to membrane blebbing and vesiculation. Surface-exposed PS strongly propagates the coagulation process by facilitating the assembly and activation of tenase and prothrombinase complexes. Factor IXa and platelet-bound factor Va support these activities. In addition, platelets can support the initiation phase of coagulation by providing binding sites for prothrombin and factor XI. They thereby take over the initiating role of tissue factor and factor VIIa in coagulation activation.
Enhanced Coagulation Activation in Preeclampsia: the Role of APC Resistance, Microparticles and Other Plasma Constituents
Authors: Boer Kees , Berckmans René , Meijers Joost , van der Post Joris , Sturk Augueste , Van Bavel Ed , Nieuwland Rienk , Van Wijk Marja 
Published: March 2018

SummaryCoagulation activation in pregnancy is further enhanced in preeclampsia. We investigated whether this results from increased thrombin generation by the plasma itself or its cell-derived microparticles. Plasma samples were obtained from preeclamptic, normal pregnant and nonpregnant women (each n = 10). Prothrombin fragment 1+2 (F1+2) and thrombin-antithrombin complex (TAT) concentrations were increased in pregnancy and further increased in preeclampsia. In pregnancy and preeclampsia, increased activated protein C resistance occurred (APC sensitivity ratio: 3.3 ± 0.8 and 2.5 ± 0.8, both P < 0.001 vs. nonpregnant). In normal pregnant microparticle-free plasma the thrombin generation correlated with TAT (r = 0.84, P = 0.005) and APC resistance correlated with F1+2 (r = 0.68, P = 0.04). In preeclampsia thrombin generation by plasma was increased (P = 0.005), independent of APC resistance. Thrombin generation by microparticles was similar in all groups, although different coagulation activation pathways were utilized, indicating that circulating microparticles are not directly involved in coagulation activation in pregnancy and preeclampsia. In contrast, APC resistance can explain coagulation activation in pregnancy, while enhanced coagulation activation in preeclampsia results, in part, from an increased thrombin generating capacity of plasma independent of APC resistance.
Von Willebrand’s Disease caused by Compound Heterozygosity for a Substitution Mutation (T1156M) in the D3 Domain of the Von Willebrand Factor and a Stop Mutation (Q2470X)
Authors: Lethagen Stefan , Isaksson Christina , Schaedel Charlotta , Holmberg Lars 
Published: March 2018

SummaryHereditary defects of the von Willebrand factor (VWF) gene cause von Willebrand’s disease (VWD) which shows great variability dependent on the nature and location of the mutation. We here describe the characteristics of a substitution of methionine for threonine 1156 in the D3 domain of the VWF, i.e. the domain involved in the intracellular multimerization of pro-VWF dimers. A VWD patient with severe symptoms was a compound heterozygote for the T1156M mutation and a null allele (Q2470X) on the other chromosome. This led to marked reduction of plasma VWF concentration to about 0.05 U/ml and an abnormality of VWF multimers as in type 2A VWD. Expression in vitro of the mutation demonstrated that 1156M-VWF is secreted from COS-7 cells in a much reduced amount and lacking large multimers. When coexpressed with normal VWF 1156M-VWF decreased the secretion of normal VWF in a dose-dependent manner, the secreted VWF showing all the multimers. Two relatives of the propositus were single heterozygotes for the T1156M mutation and were either asymptomatic or had the manifestations of mild type 1 VWD. The expression data and studies of platelet VWF indicate that the T1156M mutation results in intracellular retention of VWF rather than impaired synthesis. Three other members of the family were heterozygotes for the Q2470X mutation and demonstrated the variable expressivity of a null allele.
Effects of Enhanced P2X1 Receptor Ca2+ Influx on Functional Responses in Human Platelets
Authors: Rolf Michael , Mahaut-Smith Martyn 
Published: March 2018

SummaryG-protein-coupled P2Y1 and P2Y12 receptors play key roles in platelet activation, however the importance of ionotropic P2X1 receptors remains unclear. Platelet P2X1 responses are highly labile in vitro, but were greatly enhanced by increasing [Ca2+]o in the range 1–10 mM. The P2X1 agonist α,β-MeATP stimulated a shape change which saturated at peak [Ca2+]i of ≥ 400 nM, without evidence for aggregation. The maximal P2X1-evoked transmission decrease was 82% of that obtained via P2Y1 receptors. α., β-MeATP caused a disc to sphere transformation in virtually all platelets, but lacked the long processes produced by ADP. Following block of P2Y1 receptors with A3P5PS, co-stimulation with α., β-MeATP and ADP failed to induce aggregation despite the generation of peak [Ca2+]i responses similar to those stimulated via P2Y1 receptors. Therefore early, transient Ca2+ influx via P2X1 receptors can contribute to platelet activation by stimulating a significant morphological change, but does not readily synergise with P2Y12 receptors to support aggregation.
Magnetic resonance imaging of tumor vasculature
Authors: Chetrit-Dadiani Maya , Bogin Liora , Furman-Haran Edna , Degani Hadassa 
Published: March 2018

SummaryAngiogenic activity and formation of a vascular network facilitate tumor perfusion and play a critical role in tumor growth and metastasis. Tumor vasculature may be visualized by means of parametric imaging of specific morphological and physiological characteristics that collectively describe its properties. In this review, we describe advanced magnetic resonance imaging (MRI) techniques that have been developed in order to image and quantify the distribution of tumor vasculature throughout the tumor and characterize its function. These techniques have been used to monitor changes in the magnetic resonance signal intensity of tissue water hydrogens generated by intrinsic effects, as well as by exogenous contrast agents administered into the blood circulation. We further describe specific applications of magnetic resonance imaging using a contrast agent, gadolinium diethylene triamine penta-acetic acid (GdDTPA), which has long been approved for clinical use. Examples include studies of the vascular properties of breast cancer tumors and metastases in animal models, as well as of breast cancer vasculature in patients. We also discuss the use of MRI to improve breast cancer diagnosis in humans by quantifying the permeability of the tumor vasculature. By maximizing the spatial resolution of the images in both animal and human studies, the capacity of magnetic resonance imaging to enhance our understanding of the processes regulating tumor angio-genesis, and improve the diagnosis of cancer, could be clearly demonstrated.
The influence of exogenous magnesium chloride on the apparent INR determined with human, rabbit, and bovine thromboplastin reagents
Authors: Witteveen Evelina , Meeuwisse-Braun Joyce , van der Meer Felix , van den Besselaar Anton 
Published: March 2018

SummaryMagnesium ions can shorten the tissue factor-induced coagulation time. Some blood collection systems with sodium citrate are contaminated with variable amounts of magnesium and influence the results of the prothrombin time (PT) test. The aim of the study was to determine the dose-response relationship between exogenous magnesium chloride added to blood and the PT and the international normalized ratio (INR). Blood specimens from twenty patients on oral anticoagulant therapy were investigated. Four different types of thromboplastin reagents were used: recombinant human, human placenta, rabbit brain, and bovine brain combined with adsorbed bovine plasma. With all four reagents, exogenous magnesium induced a reduction of the apparent INR. Bovine thromboplastin was not as responsive to magnesium as the human and rabbit reagents. The magnitude of the INR deviation induced by 0.1 mmol/l magnesium in the blood was smaller than 10% in all patient samples. At 0.5 mmol/l magnesium in the blood, 10-35% of the patient samples had INR deviations greater than 10%, depending on the thromboplastin reagent used.
Chemical crosslinking of urokinase to pulmonary surfactant protein B for targeting alveolar fibrin
Authors: Ruppert Clemens , Markart Philipp , Schmidt Reinhold , Grimminger Friedrich , Seeger Werner , Lehr Claus-Michael , Günther Andreas 
Published: March 2018

SummaryIntraalveolar fibrin formation is a consistent finding in acute inflammatory and chronic interstitial lung disease. Polymerization of fibrin in the presence of pulmonary surfactant results in far-reaching incorporation of the hydrophobic surfactant compounds into the growing fibrin matrix, with loss of surface activity, altered fibrin structure and reduced susceptibility of the clot to fibrinolysis. For specific targeting of such alveolar fibrin, we designed a hybrid molecule consisting of the catalytic domain of urokinase (B-chain) and the hydrophobic surfactant protein B (SP-B), termed SPUC. The urokinase B-chain, obtained by limited reduction of human two-chain-urokinase (u-PA) and subsequent affinity purification, was chemically coupled to SP-B in a semi-organic solvent system using a hetero-bifunctional crosslinker. Purification of the chimeric proteins included reversed phase and cation exchange chromatography. SDS-PAGE and Western Blotting with immunostaining were employed for biochemical characterization of the conjugate. Chromogenic substrate assays, 125I-based fibrin plate assays, active site titration and surface tension measurements (pulsating bubble surfactometer) were performed to analyze the specific fibrinolytic activity of the conjugate and its surface activity. SPUC was found i) to be assembled stoichiometrically in a 1:1 fashion (SP-B:u-PA), ii) to fully retain the biophysical activity as compared to native SP-B and iii) to also retain the fibrinolytic activity. SPUC was 2-3 fold more effective in lysis of surfactant containing clots and 5-fold more resistant against plasminogen activator 1 (PAI-1) as compared to the native u-PA. We conclude that urokinase and SP-B can be chemically crosslinked, thereby yielding a fibrinolytic enzyme suitable for targeting alveolar fibrin.
Prolonged elevations in haemostatic and rheological responses following psychological stress in low socioeconomic status men and women
Authors: Kunz-Ebrecht Sabine , Rumley Ann , Lowe Gordon , Steptoe Andrew 
Published: March 2018

SummaryLow socioeconomic status (SES) and psychological stress are associated with increased risk of coronary heart disease, and both may influence haemostatic responses. Von Willebrand factor (vWF), Factor VIII, plasma viscosity, haematocrit, blood viscosity, tissue plasminogen activator (t-PA) and fibrin D-dimer were measured at rest and following stressful tasks in 238 middle-aged British civil servants. SES was defined by grade of employment. Lower SES was associated with higher resting vWF, Factor VIII and plasma viscosity. Psychological stress stimulated increases in haemostatic and rheological factors. Initial stress responses did not vary with SES, but Factor VIII, plasma viscosity and blood viscosity remained more elevated 45 minutes post-stress in lower SES participants. High blood pressure stress reactivity was also associated with greater haemostatic responses. We conclude that lower SES is characterised by more prolonged elevations in procoagulant responses following psychological stress, and that these processes might contribute to increased cardiac risk.
Diabetes duration may modify the association between genetic variation in the glycoprotein Ia subunit of the platelet collagen receptor and risk of severe diabetic retinopathy: a working hypothesis
Authors: Agardh Elisabeth , Teramura Gayle , Gaur Prashart , Gaur Lakshmi , Agardh Carl-David , Reiner Alexander 
Published: March 2018

SummaryGenetic factors appear to contribute to the severity and progression of diabetic retinopathy. We assessed the associations of the C807T and Glu505Lys variants of the glycoprotein Ia ( 2 integrin) subunit of the platelet/endothelial collagen receptor and risk of retinopathy in a population-based survey of 288 diabetic patients in one Swedish community. Neither variant was associated with retinopathy risk overall. However, the 807T variant was associated with increased risk of severe retinopathy, and the association was modified by diabetes duration. Among patients with diabetes of longer duration ( 25 years), the 807T variant was strongly associated with risk of severe retinopathy (odds ratio 7.49, 95% confidence interval 1.75 to 32.1). There was no association between the 807T variant and risk of severe retinopathy among patients with diabetes duration <25 years. The Lys505 variant of glycoprotein Ia was associated with an odds ratio for severe retinopathy of 1.88 (95% confidence interval 0.83 to 4.24). Overall, there was a significant interaction between glycoprotein Ia genotype and duration of diabetes on the risk of retinopathy (P-value for interaction = 0.019).These results suggest the hypothesis that genetic variation of platelet glycoprotein Ia may play a particularly important role during the advanced stages of diabetic retinopathy.