bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pentamidine Is a Specific, Non-Peptide, GPIIb/llla Antagonist
Authors: Cox Dermot , Aoki Toshiaki , Seki Jiro , Motoyama Yukio , Yoshida Keizo 
Published: July 2018

SummaryPentamidine was previously shown to act on glycoprotein (GP) Ilb/IIIa (Cox et al., Thromb Haemost 1992; 68: 731). In this paper we study the effect of pentamidine on other RGD-dependent receptors. In a cell adhesion assay, pentamidine was 500 times more potent than RGDS at inhibiting platelet adhesion to fibrinogen. While RGDS inhibited platelet adhesion to fibronectin, endothelial cell adhesion to vitronectin or fibronectin, 293 cell adhesion to vitronectin, IMR 32 cell adhesion to fibronectin and C32 cell adhesion to vitronectin; pentamidine failed to inhibit these interactions at doses as high as 1 mM. Resting platelets fixed in the presence of 1 mM RGDS had increased binding of fibrinogen, i.e., RGDS activated GPIMIIa, while pentamidine at 100 ΜM had no effect. Similarly, RGDS induced the binding of an anti-LIBS monoclonal antibody, while pentamidine had no effect. Pentamidine partially, but significantly, inhibited lysosome and a-granule release induced by the thrombin agonist peptide, while RGDS had no effect. Neither pentamidine nor RGDS affected ADP-induced Ca2+ influx. Pentamidine had no effect on ADP-induced intracellular pH changes while RGDS prevented the pH from returning to normal. Thus, pentamidine is a non-peptide GPIIb/IIIa antagonist that is non-activating and is specific for GPIIb/IIIa.
A Prostacyclin-sparing Effect of Indobufen vs. Aspirin
Authors: Caterina R De , Giannessi D , Bernini W , Lazzerini G , Lavezzari M , Stragliotto E , Biagi G , Coccheri S 
Published: July 2018

SummaryIndobufen ((±)-2-[p-(l-oxo-2-insoindolinyl)-phenyI]-butyric acid, indo) is a drug inhibiting platelet function by a reversible block of the arachidonic acid metabolism at the level of cyclooxygenase. Since tolerability profile of such drugs is mostly linked to extra-platelet cyclooxygenase inhibition, we prospectively evaluated the extent of platelet and extra-platelet cyclooxygenase inhibition by in vivo administration of indo in comparison with ASA. We assessed the effects of the two drugs on the ex vivo generation of TXB2 and 6-keto-PGFlΑ in whole blood, as indices of the production of TXA2 and PGI2 (prostacyclin), respectively, either after spontaneous clotting at 37° C for 1 h (Study 1) or after the addition of 2 Μg/ml collagen (Study 2). Generation of 6-keto-PGFlΑ in whole blood is a mixed index of platelet and extra-platelet cyclooxygenase activity, deriving from both platelet and white blood cell arachidonic acid metabolization. Fifteen patients with ischemic heart disease and baseline serum TXB2 levels > 300 ng/ml were allocated to receiving one single administration of either indobufen 200 mg (n = 6) or aspirin 500 mg (n = 9). Whole blood prostanoid generation was assessed at 0,1,2,4,6, 8,12 and 24 h after drug administration (Study 1). Ten healthy male volunteers were allocated to a double-blind, randomized crossover comparison of indo 200 mg b.i.d. vs. ASA 300 mg/d for 7 days (Study 2). Prostanoid generation and whole blood platelet aggregation were performed before and at the end of each study period (Day 0 and Day 7). At each time-point after single dose administration (Study 1), indobufen caused less % inhibition of whole blood 6-keto-PGFlΑ than of TXB2. At 2 h, TXB2 was reduced to a similar extent after ASA (98 ± 4%) and indo (97 ± 6%) (p = N.S.), while inhibition of 6-keto-PGFla was clearly different (> 98% after ASA, 81 ± 2.5% after indo, p < 0.01). After one week of ASA or indo (Study 2) the maximum extent of whole blood platelet aggregation was similarly inhibited (from 17.2 ± 1.4 ohms to 3.6 ± 1.3 ohms with ASA; from 18.3 ± 1.0 ohms to 1.6 ± 0.7 ohms with indo (p ASA vs. indo = N. S.). Despite equal inhibition of whole blood TX production after collagen (from 49.0 ± 4.3 ng/ml to 1.1 ± 0.6 ng/ml with ASA, from 49.8 ± 1.3 ng/ml to 1.4 ± 0.6 ng/ml with indo), again, however, 6-keto-PGFlΑ production was less affected by indo than by ASA (from 409 ± 30 pg/ml to 37 ± 13 pg/ml with ASA, inhibition = 91%; from 396 ± 35 to 318 ± 40 with indo, inhibition = 20%). These differential effects of indo and ASA might lead to a better platelet selectivity, tolerability and benefit/risk profile of indo vs. ASA, which are worthy of further assessment.
Comparative Effects of Staphylokinase and Alteplase in Rabbit Bleeding Time Models
Authors: Vanderschueren Steven , Collen Désiré 
Published: July 2018

Summary
Background: The pathogenesis of bleeding associated with thrombolytic therapy remains largely unknown, although spontaneous bleeding appears to correlate with bleeding time prolongation. Here, the comparative effects on cuticle bleeding times (CBT) and ear puncture bleeding times (EBT) of recombinant staphylokinase (Sak) and alteplase (recombinant tissue-type plasminogen activator, rt-PA) at equivalent doses, alone and in combination with aspirin and heparin, were studied in rabbits.
Methods and Results: Groups of 4 to 9 rabbits were allocated to one of the 8 following intravenous infusions: saline; aspirin 15 mg/kg and heparin - 100 IU/kg bolus and 10 IU/kg infusion over one hour; 1.5 mg/kg rt-PA; 1.5 mg/kg rt-PA plus aspirin and heparin; 4.5 mg/kg rt-PA; 0.5 mg/kg Sak; 0.5 mg/kg Sak plus aspirin and heparin and 1.5 mg/kg Sak. Bleeding times were determined 30 and 15 min before and 5,15,30 and 60 min after the administration over one min of saline, rt-PA or Sak, by simultaneously severing a nail cuticle (CBT) and by puncturing the ear (EBT). Bleeding times were unaffected by saline and by both doses of Sak in monotherapy. Heparin-aspirin and low dose rt-PA significantly lengthened EBT but not CBT. Both CBT and EBT were significantly prolonged (to a mean of >4 times pretreatment at 5 min) after high-dose rt-PA and after the combined administration of heparin and aspirin with either Sak or rt-PA. rt-PA provoked significantly longer bleeding than Sak in the CBT (p = 0.001; mean estimated difference = 23 min), but not in the EBT. rt-PA but not Sak degraded plasma fibrinogen dose-dependently. CBT correlated inversely with fibrinogen (r = −0.66, p = 0.001) but EBT did not.
Conclusions: At equivalent doses Sak displays a significantly higher fibrin specificity and prolongs bleeding time less than rt-PA, particularly in the nail cuticle bleeding time model in which larger vessels are injured that require fibrinogen for hemostasis.
Antithrombin-mediated Inhibition of Factor Vlla-Tissue Factor Complex by the Synthetic Pentasaccharide Representing the Heparin Binding Site to Antithrombin
Authors: Claude Lormeau Jean , Pascal Herault Jean , Marc Herbert Jean 
Published: July 2018

SummaryWe examined the effect of the synthetic pentasaccharide representing the minimal binding site of heparin to antithrombin on the antithrombin-mediated inactivation of factor Vila bound to tissue factor. This effect was compared to the effect of unfractionated heparin. Using purified recombinant human coagulation factors and either a clotting or an amidolytic assay for the determination of the residual activity of factor Vila, we showed that the pentasaccharide was an efficient antithrombin-dependent inhibitor of the coagulant activity of tissue factor-factor Vila complex. In our experimental conditions, assuming a mean MW of 14,000 for heparin, the molar pseudo-first order rate constants for ATIII-mediated FVIIa inhibition by ATIII-binding heparin and by the synthetic pentasaccharide were found to be similar with respective values of 104,000 ± 10,500 min-1 and 112,000 ± 12,000 min-1 (mean ± s.e.m., n = 3)
T Lymphocyte Proliferative Responses Induced by Recombinant Factor VIII in Hemophilia A Patients with Inhibitors
Authors: Singer Sylvia T , Addiego Joseph E , Reason Donald C , Lucas Alexander H 
Published: July 2018

SummaryIn this study we sought to determine whether factor VUI-reactive T lymphocytes were present in hemophilia A patients with inhibitor antibodies. Peripheral blood mononuclear cells (MNC) were obtained from 12 severe hemophilia A patients having high titer inhibitors, 4 severe hemophilia A patients without inhibitors and 5 normal male subjects. B cell-depleted MNC were cultured in serum-free medium in the absence or presence of 2 µg of recombinant human factor VIII (rFVIII) per ml, and cellular proliferation was assessed after 5 days of culture by measuring 3H-thymidine incorporation. rFVIII induced marked cellular proliferation in cultures of 4 of 12 inhibitor-positive hemophilia patients: fold increase over background (stimulation index, SI) of 7.8 to 23.3. The remaining 8 inhibitor-positive patients, the 4 hemophilia patients without inhibitors and the 5 normal subjects, all had lower proliferative responses to rFVIII, SI range = 1.6 to 6.0. As a group, the inhibitor-positive subjects had significantly higher proliferative responses to rFVIII than did the inhibitor-negative and normal subjects (p < 0.05 by t-test). Cell fractionation experiments showed that T lymphocytes were the rFVIII-responsive cell type, and that monocytes were required for T cell proliferation. Thus, rFVIII-reactive T lymphocytes are present in the peripheral circulation of some inhibitor-positive hemophilia A patients. These T cells may recognize FVIII in an antigen-specific manner and play a central role in the regulation of inhibitor antibody production
Cysteinyl Leukotriene D4 Induced Vascular Smooth Muscle Cell Proliferation: A Possible Role in Myointimal Hyperplasia
Authors: Porreca Ettore , Di Febbo Concetta , Sciullo Anna Di , Angelucci Domenico , Nasuti Mimmo , Vitullo Paola , Reale Marcella , Conti Pio , Cuccurullo Franco , Poggi Andreina 
Published: July 2018

SummaryCysteinyl leukotrienes (i.e. LTC4, LTD4), produced by activated leukocytes or by transcellular metabolism may act at different levels on vascular smooth muscle cells (VSMC) during inflammatory processes or atherosclerosis. We studied the effect of LTC4, LTD4, and LTE4 on the in vitro proliferation of rat VSMC, measured by [3H]-thymidine incorporation and cell count. LTD4 had a stronger stimulatory effect on [3H]-thymidine incorporation than LTC4, whereas LTE4 was inactive. The effect of LTD4 on [3H]-thymidine incorporation was dose-dependent, with the maximal activity at 10−6 M. The stimulatory activity of LTD4 was inhibited in a dose-dependent manner by MK-571, a specific LTD4 receptor antagonist. In addition, MK-571 (1 mg/kg/day) given for at least 1 day after injury in a model of balloon catheter injury of rat carotid artery, provided effective inhibition of myointimal VSMC proliferation, with a 58% reduction of 5-bromo-2’-deoxyuridine (BrdU) uptake in the neointima and 69% reduction of neointimal thickening. Our data support the importance of inflammatory mechanisms in the pathogenesis of atherosclerosis and suggest a possible role for cysteinyl leukotrienes, specifically LTD4, in the control of VSMC proliferation.
Deep Venous Thrombosis and Lupus Anticoagulant
Authors: Simioni Paolo , Prandoni Paolo , Zanon Ezio , Saracino Maria A , Scudeller Alberta , Villalta Sabina , Scarano Luigi , Girolami Bruno , Benedetti Lino , Girolami Antonio 
Published: July 2018

Summary
Background. A definite evidence in favour of an association of deep-vein thrombosis (DVT) with lupus anticoagulant (LA) in patients free from systemic lupus erythematosus is still lacking.
Methods. In a case-control study, LA was determined in 176 consecutive outpatients who underwent phlebography because of the first episode of clinically suspected DVT of lower limbs. The association between DVT and LA was described using odds ratios (OR).
Results. Contrast venography confirmed the clinical suspicion in 59 patients (33.5%). LA was detected in 5 of the 59 patients with DVT (8.5%), and in none of the 117 subjects with normal venogram (P = 0.007). The OR for having an acute DVT in patients with LA was 10.7 (95% CI: 1.2-94.2).
Conclusions. LA is significantly associated with DVT in symptomatic patients. Further studies are needed to establish the clinical implications of this association.
Surface Coverage of Vascular Grafts with Cultured Human Endothelial Cells from Subcutaneous Fat Tissue Obtained with a Biopsy Needle
Authors: Koyama Masayuki , Satoh Kei , Yoshida Hidemi , Suzuki Sohei , Koie Hisaaki , Takamatsu Shigeru 
Published: July 2018

SummarySurface coverage with autogeneous endothelial cells is effective in reducing thrombogenicity of an artificial vascular graft, but procedure for obtaining the cells is invasive for patients. The purpose of this study was to establish cultures of human endothelial cells separated from a small piece of subcutaneous fat tissue. A piece of tissue weighing about 10 mg was obtained from subcutaneous fat using a biopsy needle, and treated with collagenase and dispase. Microvascular endothelial cells were selected and other types of cells contaminating the cultures were eliminated by scraping with a needle under a microscope. The yield of the cells was 8362 ± 4264/10 mg of subcutaneous fat (n = 7). The cultures reached confluence in about 2 weeks. The cells were positive for von Willebrand factor, P-selectin, and uptake of acetylated low density lipoprotein. The cells produced 15.9 ± 3.3 ng/mg cell protein/h of 6-ketoprostaglandin F1α (n = 5) when stimulated with thrombin. Thrombin also stimulated the production of platelet-activating factor: 7653 ± 4297 dpm/106 cells (n = 5). Endothelin-1 accumulation in the medium of unstimulated endothelial cells was 0.54 ± 0.16 ng/mg cell protein/10 h (n = 8). As a preliminary experiment for graft seeding, the cells were also cultured on pieces of a gelatin-coated Dacron graft, and scanning electron microscopy revealed the surface coverage of the graft. We herein described about successful culture of human microvascular endothelial cells from subcutaneous fat tissue obtained using a biopsy needle. The cultured cells may be applicable to a seeded vascular graft.
A Monoclonal Antibody To VIII:C Produced By A Mouse Hybridoma
Authors: Muller H P , van Tilburg N H , Bertina R M , Derks J , Klein-Breteler E 
Published: July 2018

Spleen cells of a Balb-c mouse immunized with VIII:C (isolated by affinity chromatography) were fused with mouse myeloma cells (MOPC-21 derivative). After the fusion 12/32 wells produced an inhibitor to VIII:C. After subclonation (3 x) a stable hybridoma line was obtained. The antibody in the supernatant was detected with a modified VIII: Cinhibitor technique. The supernatant of in vitro cell cultures of the hybridoma cells contained anti-VIII:C titers (Bethesda) of about 0.3-1.0 units/ml. Injection of the hybridoma cells in pristane pretreated Balb-c mice results in anti-VIII:C titers of 5,000-10,000 units/ml ascites.Analysis of the produced immunoglobulin demonstrated the presence of one band after isoelectric focussing, which contained heavy chains both of IgG1 and IgG2B subclass. Because of the unusual kinetics of the monoclonal antibody with VIII:C extensive characterisation of the nature of its VIII: C neutralising properties was necessary.The monoclonal antibody does not bind 125I-fibrinogen or isolated VIIIR:AG, it reacts with isolated VIII:C and can be used in a two-site immunoradiometric assay for VIIICAG. The epitope against which the antibody is directed is not present on ‘serum-VIIICAG’.
Abnormal Prothrombin Consumption (Pc) In Bernard Soulier-Syndrome (BSS)
Authors: Pizzuto J , Reyna M P , González-Angulo A , Morales M R , Dorantes S 
Published: July 2018

The abnormal PC in BSS is a defect that has not been extensively studied to date. For this reason 4 patients with BSS who had normal platelet aggregation tests (except with bovine fibrinogen and with Ristocetin), but abnormal bleeding times and PC on different occasions, during which they showed variable thrombocytopenia, were studied. The PC was normal in only one case and in only one occasion, which was coincidental with a circulating platelet count that also approximated normal.The abnormal PC in the 4 cases was corrected when platelet substitute, or washed platelets from normal subjects or from patients with BSS were added. These same platelets also corrected the abnormal PC in cases of ITP or aplastic anemia, and shortened the recalcification time of platelet-poor plasmas from normal subjects and patients with specific plasma deficiencies (Factors V, VIII and XI).The above suggests that the abnormal PC in some cases of BSS may be due to the thrombocytopenia rather than to a defect in the procoagulant activity of the platelets in this syndrome.
A Functional Basis For The Platelet Storage Pool Deficiency In Chediak-Higashi Cattle
Authors: Meyers K M , Fukami M , Holmsen H 
Published: July 2018

Platelets from cattle with the morphologic homolog of the Chediak-Higashi (CH) syndrome are essentially devoid of secretable nucleotides and serotonin. There are reduced but still substantial amounts of secretable calcium and magnesium. The storage pool deficiency may be, in part, due to a functional granule defect. Platelets from CH cattle take up serotonin and protect it from degradation for several hours. If these platelets are treated with thrombin, serotonin and bivalent cations are released by mechanisms similar to that of secretion, suggesting a granule location for the released serotonin and cations. This suggestion is verified by subcellular fractionation studies where platelets are first incubated with 14C-serotonin then lysed using a French press. Organelles were then separated on a sucrose gradient by centrifugation. Serotonin in normal bovine platelets is associated with the dense granule or pellet while in CH platelets serotonin is primarily found in a region of the sucrose density zone that in normal platelets contain alpha granules. These findings suggested that some granules in CH platelets are able to acquire the bivalent cation and amine but not the nucleotide component of the bivalent cation-nucleotide-amine storage complex that is thought to occur in normal dense granules.Ultrastructural identification of the serotonin-containing CH granule is not known. There are 2 identifiable granule populations in CH platelets, alpha granules and fibrous matrix granules. Based on serial sectioning freeze fracture and morphometric studies, there are less than 4 of these granules/platelet. Mepacrine studies also demonstrate 2 granule populations. One population has an incidence of 2 per granule and characteristics of normal dense granules. Since the number of fibrous matrix granules and mepacrine granules is similar, a common basis for these granules which has at least some dense granule characteristics, i.e., mepacrine storage, is suggested.
Protein Synthesis In Megakaryocytes Stimulated By Thrombo- Poietin In Vitro
Authors: Kellar K L , Evatt B L , McGrath C R , Ramsey R B 
Published: July 2018

Studies in our laboratories have been concerned with the responses of megakaryocytes to thrombopoietin in vitro. We have shown that preparations of thrombopoietin stimulate DNA synthesis in guinea pig megakaryocytes. The increase in 3H-thymidihe incorporation correlates with an increase in the labeling index of the megakaryocytes. After 2 and 3 days of incubation an increase in the ploidy levels of the megakaryocytes has been observed in thrombo- poietin-supplemented cultures compared to controls.Recent studies have examined the incorporation of 3H-leucine in megakaryocyte cultures. Megakaryocytes were prepared on BSA or Percoll gradients to purities of 70-95%. 3H-leucine incorporation was measured after a 15 hr incubation of the megakaryocytes in medium containing 10% thrombopoietin or control preparations of normal plasma or phosphate-buffered saline. Utilization of isotope increased over a 24 hr period and was higher in the thrombopoietin-supplemented cultures. In addition, synthesis of specific proteins was analyzed by using SDS- polyacrylamide gel electrophoresis and quantitation was achieved by employing rocket immunoelectrophoresis. The results indicate that thrombopoietin stimulates endoredu- plication and protein synthesis in megakaryocytes in vitro and that this system may serve as a model for studying the mechanism of action of thrombopoietin in megakaryocytopoiesis.
Interaction Of Atherogenic (VLdL; LdL) And Non Atherogenic Lipoproteins (HDL) With Heparin Fractions Of Various Molecular Size
Authors: Duthilleul P , Fievet P , Bouillet L , Fruchart J C 
Published: July 2018

Some anticoagulant properties of various heparin fractions (with molecular weights from 5 000 to 20 300 daltons) have been investigated in purified and plasmatic systems with and without Lipoproteins isolated by ultracentrifugation from hyperlipemic subjects (type IIa). Amidolytic (Tos-Gly-Pro-Arg-pNA) and coagulometric (Yin and Wessler) anti Xa activity of a HMW fraction (231 USP/mg. MW: 20 300) was decreased from 15 %m both systems supplied with LDL or VLDL since HDL have no effect. No influence was detected on anti Ila activity (Phe-pro-arg-AIE fluorimetric method). LMW (20 USP/mg ; MW 6 000 - 8 000) and ULMW (20 USP.MW 4 000-5 000) anti Xa and anti Ila activities was modified neither by VLDL/LDL neither by HDL. These findings point out to differences in the mechanisms of inhibition of thrombin and Xa by various molecular weigh heparin fractions.Two dimensional crossed Immunoelectrophoresis in agarose 1 % with mixing various quantities of each heparin fraction (0 - 100 μg/ml) in the first phase of electrophoresis of LDL/VLDL, LDL/VLDL and AT III, LDL/VLDL and FXa reveal the presence of LDL or VLDL/heparin fractions complexes and LDL or VLDL/AT III complexes, which are isolated by Gel filtration on Ultrogel A 6. We conclude that FXa can escape from neutralization by inactive complexes.
The Effect Of The Natural Proteinase Inhibitor Aprotinin On The Activation Of Platelet Function During Total Hip Replacement
Authors: Ketterl R , Haas S , Lechner F , Kienzle H , Blüme G 
Published: July 2018

Postoperative thromboembolism is a well known problem after total hip replacement. Besides the intravasation of bone marrow and thromboplastic material it is discussed that it is caused by activated platelets. Therefore, we focussed our interest on platelet function during total hip replacement.In 12 male and female patients (age:52-84 years) with total hip replacement blood samples were taken at the following time intervals: 1.induction of anesthesia, 2.arthrotomy, 3.preparation of the acetabulum, 4. polymerization of the bone cement in the acetabulum, 5. preparation of the bone marrow in the femur shaft, 6. implantation of the prosthesis shaft, 7.2 hours postoperatively. A second group of 14 patients (age:55-81 years) was treated with 20 000 KIU/ kg BW aprotinin (TrasylolR) immediately after induction of anesthesia. Following tests were carried out: 1. platelet morphology according to KRZYWANEK, 2. platelet adhesiveness according to MORRIS, 3. collagen-induced platelet aggregation according to BORN, 4. spontaneous platelet aggregation according to BREDDIN.The number of shape-changed platelets is increasing with the duration of the operation and the maximum is to be seen when the femur shaft is prepared for the prosthesis. In contrast to these findings only a slight increase of shape- changed platelets occurs after application of aprotinin. Concerning the adhesiveness of platelets corresponding results were found. Platelet aggregation induced by collagen was also increased during the operation time. The increase of the aggregability characterized by the maximal amplitude was not seen in the aprotinin-group. The spontaneous platelet aggregation was enhanced in the non-treated group (angle α 2↑ maximal amplitude↑) whereas this phenomenon was not observed after application of aprotinin. The total hip replacement is closely related with a stimulation of platelet function. This could be the origin of postoperative thromboembolism.