bluuebunny/crossref_metadata_2025_split huggingface dataset:
EXTRINSIC ACTIVATION OF HUMAN COAGULATION FACTORS IX AND X ON THE ENDOTHELIAL SURFACE
Authors: Bom V J J , van Hinsberqh V W M , Reinalda-Poot J H , Mohanlal R W , Bertina R M 
Published: August 2018

In previous studies using purified human tissue factor (TF) apoprotein reconstituted with PS/PC membranes, no dramatic differences between the kinetic parameters for extrinsic activation of factor X (FX)and factor IX (FIX)could be observed. In vivo however, TF is an integral part of a complex biological membrane. Therefore we studied the kinetics of extrinsic FX and FIX activation on endothelial cells.TF expression was stimulated by incubation of cultured human endothelial cells with endotoxin (4 hr). The cells were washed and incubated with FVII(a), FX and/or FIX n the presence of CaCl2. FXa and FIXa formation were measured with a sensitive spectrophotometric assay (S2337) and an immunoradiometric assay (IRMA-IXa), respectively. Unstimulated cells did not induce significant activation of FX or IX. Stimulation of the cells and recombination of exposed TF withFVIIa resulted in rapidactivation of both substrates.Rates of FXa formation reached a maximum after a lag of about 1 min. Upon prolonged incubation the rate of FXa formation progressively decreased, probably by inactivation of FVIIa by product Xa. At the other hand, FIXa formation was linear in time for at least 30 min. When added together, FIX was found to be a weak, competitive inhibitor of FX activation, while FIX activation was severely inhibited by FX. Both FX and FIX activation were dependent on the presence of TF (sensitive to µ-TF antibodies) and FVIIa. The calculated Km of FIX (∼0.09µM) and of FX (∼0.07µM) for extrinsic activation at the endothelial surface were both higher than those observed in a cell free system using purified TF apoprotein and the ratio of Km-FIX/Km-FX was about 6-fold increased. The ratios of Vmax-FIX activation/Vmax-FX activation for both systems were similar (−0.3). These data indicate that the microenvironment of TF in the biological membrane does not introduce important alterations in the kinetic parameters of TF-FVIIa dependent activation reactions in favour of extrinsic FIX activation.
IMMUNE THROMBOCYTOPENIA (ITP) : PLATELET TARGET ANTIGENS OF THE ANTIBODIES IN DIFFERENT CLINICAL SETTINGS
Authors: Beardsley D S 
Published: August 2018

Autoantibodies against platelet antigens are important in the pathogenesis of ITP. We have studied the antigenic targets of these autoantibodies by immunoblotting using electrophoretically separated proteins from normal, Glanzmann's Thrombasthenic, and Bernard-Soulier Syndrome platelets immobilized on nitrocellulose paper. Incubation of these proteins with ITP patient serum, immunoglobulin, or F(ab*>2, followed by labeled antiglobulin, allowed identification of the antigenic target glycoproteins (GPfs). Patients with ITP of several categories were studied: A) Chronic ITP (> 1 yr duration) including a subset of patients who hadmild thrombocytopenia but significant hemorrhagic manifestations. B) Acute ITP (<6 mo) following varicella infectionAcute onset ITP unresponsive to any of the usual therapeutic modalities. A majority of patients in group A (32/48) had antibodies directed against a protein with a MW of lOOkD. In some cases, the target antigen was localized to GPIIIa specifically by absence of reactivity with Type I Glanzmann's thrombasthenic platelets known to be totally deficient in GPIIb and Ilia. Two individuals in the subset with unexpectedly severe hemorrhagic symptoms also had anti-GPIIIa antibodies, but the antigenic target was different since only these two antibodies could be shown to interfere with binding of 125j_fibrinogen to normal plateletsIn contrast to the individuals with anti-GPIIIa antibodies, all group B patients (7/7) with acute post-varicella ITP had antibodies directed against an 85kD thrombin sensitive protein, and two of the three group C individuals studied showed antibodies directed against GPIb. These studies indicate that a number of different platelet antigens can be the targets of platelet autoantibodies in ITP. Results suggest that antibodies against a particular antigen may correlate with a similar clinical setting in different patients. Further work will determine whether antigen identification at the time of diagnosis can be used to predict the clinical course for an individual patient
MECHANISMS OF IMMUNOLOGIC THROMBOCYTOPENIA IN INDIVIDUALS AT RISK FOR AIDS
Authors: Karpatkin S 
Published: August 2018

HIV-seropositive homosexuals, narcotic addicts and hemophiliacs develop a new syndrome of immunologic thrombocytopenic purpura (ITP) which is clinically indistinguishable from classic autoimmune thrombocytopenic purpura (ATP) with respect to increased megakaryocytes in the bone marrow, peripheral destruction of antibody-coated platelets, negative serology for SLE, response to treatment with prednisone and/or splenectomy. However, their platelet immunologic profiles are different.Homosexuals appear to have an immune complex-mediated mechanism: markedly elevated platelet-bound IgG and C3C4 (3.8 and 4.2-fold greater than classic ATP, respectively), elevated circulating immune complexes (3-fold greater than classic ATP), anti-F(ab')2 antibodies and absence of 7S anti-platelet IgG. There is no inverse correlation between platelet count and platelet-bound IgG or platelet-elutable anti-platelet antibody as in classic ATP.Hemophiliacs appear to have an autoimmune 7S IgG-mediated mechanism similar to classic ATP: inverse relationship betweem platelet count and platelet-bound IgG, r = 0.84, p less than 0.001, 26 df, anti-platelet reactive 7S IgG which reacts by its F(ab')2 domain, (reactive at 60-130 ug/ml compared to control IgG), platelet-elutable anti-platelet antibody. However, these patients also have elevated circulating immune complexes (2.4-fold classic ATP level) and markedly elevated platelet-bound IgG and C3C4 (3.4 and 1.2-fold classic ATP level, respectively). Anti-HIV antibody correlated with circulating immune complexes, r = 0.833, p less than 0.001.Narcotic addicts appear to have a mixture of both mechanisms (immune complex as well as autoimmune 7S IgG): markedly elevated platelet-bound IgG and C3C4 (2.6 and 2.4-fold classic ATP level, respectively), elevated circulating immune complexes (7.3-fold classic ATP level), anti-F(ab')2 antibodies, absence of an inverse correlation between platelet count and platelet-bound IgG. However, these patients do have specific 7S IgG anti-platelet antibody, which reacts by its F(ab')2 domain.F(ab')2antibodies were of the IgG class and correlated with circulating immune complex level. They react with autologous, homologous patient and healthy control F(ab')2 fragments. Some anti-F(ab')2 antibodies have broad reactivity, others are more limited. Some immune complexes were shown to contain HIV antibody. It is postulated that the immune complex platelet deposition noted with homosexual and narcotic addict thrombocytopenia may in part be due to HIV antibody complexes, some of which may exist as anti-antibody complexes.
THE EFFECT OF COAGULATIOU CHANGES ON THE OUTCOME OF GASTROINTESTINAL HAEMORRHAGE
Authors: Blair S D , Tan K K , McCollum C N , Greenhalgh R M 
Published: August 2018

Blood is hypercoagulable following GI haemorrhage [1], and vascular thrombosis has been reported to be the main cause of death [2]. To study the relationship between coagulation and clinical outcome, Impedance Clotting Time (ICT) wac measured daily using the Biobridge [1] and clinical outcome prospectively recorded in 125 patients with acute severe GI haemorrhage.Mean (±se mean) ICT on admission was markedly shortened at 4.8±0.2 mins (normal range 8-12 mins) (p<0.001, t-Cest). Sixty patients received blood transfusion within 24 hours resulting in significantly prolonged ICT of 6.2±0.4 mins compared to 4.0±0.3 mins in the 56 not transfused (p<0.01). In 23 patients who rebled, the ICT at 24 hours of 6.7±0.4 mins demonstrated reduced hypercoagulability. Twenty of these 23 patients had bee:: transfused prior to rebleeding, a significantly greater proportion than in those who did not rebleed (p<0.00l). Six patients died, 3 of myocardial infarction, 1 of stroke, and 2 of continued haemorrhage. Mean ICT in the 4 patients dying from thrombotic vascular disease was 2.3±0.1 mins although 2 had also rebled.Clinical outcome in GI haemorrhage is strongly related to coagulation changes. The main cause of death was thrombotic vascular disease.1. Blair SD, Janvrin SB, McCollum CN, Greenhalgh RM. The effect of early blood transfusion on gastrointectinal
haemorrhage. Br J Surg 1986; 73: 792-4.2. Allan R, Dykes P. A study of the factors influencing mortality rates fron gastrointestinal haenorrhage. Quart JMed 1976; 180: 533-50.
ADENOCARClNOMPrOF COLON AND THROMBOSIS: INCREASED THROMBIN,PLASMIN OR NEUTRAL PROTEASES ACTIVITY
Authors: Grand B , Blanco A , Kempfer A , Elgue G , Riveros D , Lazzari M 
Published: August 2018

Thrombotic and hemorrhagic complications are common in cancer patients and are an important cause of morbidity andmortality in these subjects.Hemostatic abnormalities, with or without these complications are found in nearly 95% of these patients .These abnormalities havebeen atributed to the presence of intravascular coagulation produced by an increased fibrin gene rat ion. We report apatient with adenocarcinoma of colon and multiple venous thrombosis, whose laboratory findings were consistent with anincreased proteolytic activity different from thrombin or plasmin.A 36 year old man with deep vein throrribosis and adenocarcinoma of colon was admitted^He started anti coagulationwith heparin and continued with acenocoimarine.In spite of a correct range of anticoagulation he developed a pulmonarthromboembolism and an axilar vein thrombosis.Coagulation studies on admissionwere as follows: Platelet count;250xl03/μl ,APTT;33 sec.,Prothrombin time;80%,FII; 150%,FV;110%,FVII-X;90%,FVIII;220%,FIX;210%,FDP;156pμ/ml.Thrombin time was shortened and clot solubility in urea 5 M was normal. Euglobulin lysis time and plasminogen(S-2251) were normal.The antithrombin 111 (AT III) concentration measured with specific antiserum (107%) and chromogenic substrates (95%) were normal.The ATIII crossed immunolectrophoresis(CIE) did not show the presence of thrombin-ATI 11 complexes .Studies on von Willebrand factor (vWF) revealed:elevation of vWF:Ag(511%) and normal ristocetin cofactor acti vity(vWF:RCof)(110%); the CIEshowed an increased mo-bi 1 ity( 1.46).Immunological levels of FXIII subunits A and S were decreased(30% and 41%) .Spontaneous proteolytic acti vity(SPA) measured with S-2288 was elevated.Though coagulation findings were consistent with consumption coagulopathy, classicaly related to thrombin gene rati on, thenormal levels of ATI 11 and the abscence of thrombin-ATIII complexes speaks against thrombin intervention.In addition, no evidence of primary fibrinolysis was observed.The increased SPA,the low levels of FXIII subunits A and S, and a faster mobility of vWF:Ag with an increased vWF:Ag/vWF:RCof ratio, suggest that hemostatic abnormalities in this patient could be due to proteolytic degradationof clotting factors by enzymes released from tumoral cells or granulocytes.
IRREVERSIBLE INHIBITION OF THE THROMBIN-MEDIATED SIGNAL TRANSFER
Authors: Visser A , Meuleman D G 
Published: August 2018

The inhibition of the thrombin-mediated signal transfer by a common irreversible inhibitor Z of the factor Xa complex (Xc
a) and thrombin has been analysed for the two-step process of the Xc
a-triggered formation of thrombin andthe consecutive splitting ok a thrombin-specific substrate S. Assuming that both proteolytic processes follow simple Michaelis—Menten kinetics, that the inhibition reactions are second-order and that the prothrombin and irreversible inhibitor are in excess it can be shown that:1. clotting time (tc) is inversely proportional to the time-averaged thrombin concentration2. the endpoint of the conversion of the thrombin specific substrate S reached at exhaustion of thrombin and the Xc
a is inversely proportional to the square of the inhibitor concentration3. the continously monitored thrombin generation inhibition is a more sensitive assay than the classical two-stage thrombin generation inhibition assay4. the shift in the effective concentration range of the continuously monitored thrombin generation inhibition assay relative to the continuously monitored anti-Xa assay and to that of the continuously monitored anti-IIa assay, depends on the initial rate of formation of thrombin with the thrombin generation inhibition assay and the original enzyme concentrations of the anti-enzyme assays.It can further be shown that the above conclusions still hold when the Z-mediated (with Z = anti thrombin III e.g.) inhibitions are potentiated by heparin(oid)s.
PHOTOMETER-LINKED MICROCOMPUTER SYSTEM ENABLES PRECISE CHROMOGENIC PROTHROMBIN TIME ASSAYS
Authors: Siekmann U , Dittrih D , Zimmermann R E 
Published: August 2018

In coagulation diagnostics photometric assay procedures are in widespread use. Due to the availability of new specific chromogenic peptide substrates, automated instruments play an important role in clinical routine laboratory diagnosis. For research work, the benefit of expensive industrial photometric coagulation systems is questionable, especially as the program cannot be adapted by the user. For this purpose we developed an inexpensive microcomputer-controlled measuring system as well as a suitable photometric assay which allows to determine chromogenic clotting times with any conventional spectrophotometer.Absorbance data were taken from the analog chart-recorder output of a double-beam spectrophotometer, digitized by a 12 bit analog-to-digital converter and read by the computer via an interface. Menu driven, user orientated / user dialogue based compiled BASIC software was written to enable data acquisition and processing.During the chromogenic assay procedure, automatically collected absorbance data were displayed, stored, analyzed immediately, saved on disk for later kinetic analysis and printed.Preliminary results with our chromogenic PT-assay indicate excellent reproducabi1ity of the test. The clotting time itself is defined as the interval from the beginning of the test to the moment when a preselected absorbance change occurred. Standard curves can automatically be calculated by regression routines after measurement of reference values.It must be emphasized that the occurence of fibrinogen-generated turbidity during the chromogenic assay sometimes influences the total absorbance significantly. For this reason the reaction time has to be limited by a low optical endpoint setting.
EVALUATION ON EFFECTIVENESS OF LOW DOSE ASPIRIN THERAPY FOR PROTECTION OF THROMBUS FORMATION
Authors: Kariyone S , Hirakuri M , Yui T , Uchida T 
Published: August 2018

In order to protect thrombus formation, administration of low dose aspirin has become common. However, its significance for this purpose is still not clear. Effect of small dose of aspirin (ASA) onplatelet aggregation and ability of malondialdehyde(MDA) formation in platelet by the addition of arachidonic acid in vitro were investigated. In clinical study, platelet aggregation, MDA formation of platelet, serum P-thromboglobulin(p-TG), platelet factor 4(PF4) and thromboxane B2(TX-B2) levelswere measured before and after low doseaspirin therapy.Platelet aggregations by ADP, collagen, epinephrin and arachidonate as inducers were significantly suppressed under 12.5 ug/ml ASA in the medium. MDA formation of platelet was remarkably inhibited under 1.6 ug/ml of ASA in the medium in vitro.In patients, single oral dose of 50 mg ASA showed no change on platelet aggregation while the ability of MDA formation decreased 50# of the before. Serum concentration of ASA after oral dose of 50 mg ASA only showed 1.5 to 6.0 ug/ml at maximum.Daily dose of 50 mg ASA was continued during 10 days. Changes of various factors due to the time course were observed. Inhibitions of platelet aggregation were seen from 5th day on ADP and collagenand from 2nd day on epinephrin and arachidonate as inducers during the therapy. MDA formations of platelet were decreased quickly and it became almost zero at 5th day. ASA levels in the patient serum reached plateau as 8 or 9 ug/ml from 3rdday.Various patients with a possibility of thrombus formation were administered daily 50 mg ASA during 10 days. Platelet aggregations and MDA production, serum β-TG, PF4 and TXB2 levels were measured before and after the therapy. Platelet aggregations by ADP, collagen and epinephrin as inducers were significantly suppressed after the therapyand MDA production of platelet was also markedly decreased after the therapy. There were no significant changes in serumβ-TG and PF4 levels while TXB2 level tended to decrease after the therapy.From these results, it was concluded that daily 50 mg ASA oral dose was certainly effective for protection of thrombus formation.
AN EXTRACT OP FEVERFEW INHIBITS INTERACTION OP HUMAN PLATELETS WITH COLLAGEN SUBSTRATES
Authors: Lösche W , Mazurov A V , Groenewegen W A , Heptinstall S A , Repin V S 
Published: August 2018

Feverfew (Tanacetum parthenium) has been used since ancient times as a herbal remedy for migraine, fever and arthritis. Recently it has been shown that extracts of feverfew inhibit aggregatory and secretory responses in human platelets induced by various soluble agonists.The interaction of platelets with surfaces coated with human collagens of type III (C III) and IV (C IV) has been studied by measuring the deposition of 51-Cr-labelled platelets and by scanning electron microscopy. Experiments were performed using platelet-rich plasma (PRP) and suspensions of gel-filtered platelets. Platelets were deposited on C III mostly as surface-bound aggregates. In contrast they were deposited on C IV mostly as spread forms of individual cells. Formation of aggregates on C III was more extensive for PRP than for GPP; in contrast platelet spreading on C IV was more extensive for GPP than for PRP.Feverfew extract inhibited the deposition of 51-Cr-labelled platelets on both C III and C IV in a dose dependent way. Similar concentrations of extract were needed to inhibit the formation of surface-bound aggregates and to inhibit platelet spreading in both PRP and GPP.The results indicate that feverfew may have antithrombotic potential in addition to its claimed benefit in certain clinicalconditions.
INFLUENCE OF CELL CYCLING ON MAGNITUDE OF RESPONSE OF HUMAN UMBILICAL VEIN ENDOTHELIAL CELLS (EC) TO NOREPINEPHRINE (NE) AND HISTAMINE (H)
Authors: Gupta M , Stewart G J 
Published: August 2018

EC have several roles in preventing thrombosis. Efficiency with which EC fulfill these might well influence outcome of potentially thrombotic stimuli. Thus, factors that influence EC function are of interest. As a general measure of EC response to NE and H the level of cAMP was measured. EC were harvested and passaged by enzymatic digestion and grown in DMEM plus 10% fetal calf serum and antibiotics. cAMP was assayed by radioimmunoassay. Percentage cycling cells was determined by autoradiography of cultures pulse labeled with tritiated thymidine and was increased by hydroxyurea treatment.Basal cAMP was remarkably consistent (less than 10% difference) for cells isolated from different cords, studied after different number of passages, fresh or frozen and with varying percentage of cells cycling. However, magnitude of response to agonists was highly variable. Within the same cell lot between 5-8 passages, magnitude of response was directly proportional to percentage of cycling cells but magnitude ofresponse for different cell lots varied over several fold.EC response to NE was mediated through B-adrenergic receptors and that to H through H receptors. Variability might be caused by differences in receptor number or some intracellular process.
EFFECTS OF MECHANICAL FORCE ON BLOOD FIBRINOLYTIC ACTIVITY
Authors: Takashima N , Tsuruta H , Higashi T , Watanabe M , Isomoto A , Tyuma I 
Published: August 2018

The effects of exposure to mechanical force on the blood and blood vessels were studied concentrating on the factors of thrombosis and hemostasis. (I) The palms of 10 healthy males were exposed to mechanical vibration (35 Hz, 5 G, 5 mm p-p) for 5 min. Euglobulin fractions were separated from the pre- and postvibration blood samples. The fibrinolytic activity, measured with the fibrin plate method, increased after vibration; fibrinolytic areas (pre/post) = 15.3 ± 6.0/18.6 ± 8.4 mm2 . The tissue-type plasminogen activator (t-PA) from endothelial cells of blood vessels was measured with the same blood samples by an enzyme-linked immunosorbent assay using monoclonal antibodies. It was proportional to the fibrinolytic activity; t-PA (pre/post) = 1.36 ± 1.09/1.58 ± 1.21 ng/ml. This suggests that the t-PA from the endothelial cells participates in increasing the fibrinolytic activity. (II) Six healthy males performed the side-step test for 5 min. At pre- and post-exercise, blood was collected from the great saphenous vein and its t-PA was measured to investigate the direct effect of mechanical force on the sole of the feet. As a control, the t-PA of the median venous blood was also measured. When the side-step test was performed with bare feet, the t-PA increased in the great saphenous venous blood, but not so much in the control. On the other hand, when the same test was done with the subjects wearing shoes, the t-PA did not increase. These data show that the mechanical force directly releases t-PA from the endothelial cells of the foot vessels in the soles of the feet, and that shoes can protect the feet from shock.The influence of physical exercise on fibrinolytic activity is well known. In the mechanism, endothelial cells are thought to be stimulated by vasoactive hormones. However, the direct influence of mechanical force on the blood vessels must also be considered.
MONOCLONAL ANTIBODIES To D-DIMER: DISCREPANT LATEX AGGLUTINATION AND EIA RESULTS IN LIVER DISEASE PATIENTS
Authors: Carr JM , McKinney ML , Neuringer I , McDonagh J 
Published: August 2018

Measurement of fibrin (ogen) degradation products (FDP) by latex agglutination with polyclonal antifibrinogen may be falsely elevated in liver disease due to the presence of “poorly clottable” fibrinogen in serum (Blood 67:1468, 1986). TSro monoclonal antibodies recognizing different epitopes of fibrin degradation fragment D-dimer (DD) are now commercially available. Because of the reported lack of crossreactivity of the DD monoclonals with fibrinogen, we employed them as tools to distinguish true fibrinolysis from false positive results due to liver disease. 17 citrated plasmas were evaluated by 5%SDS PAGE, nitrocellulose transfer and polyclonal antifibrinogen blotting for detection of FDP (X,ED,Y,D). Samples were then evaluated for ED by latex agglutination and by EIA (enzyme immunoassay) with the following results:Patients in Groups 3a and 3b were jaundiced (bilirubins 3.2-27) and had either hepatitis or cirrhosis except for one patient in Group 3a who had metastatic cancer. Assay for soluble fibrin monomer (SFM) by hemagglutination was negative in group 3b but positive in 5 of 7 patients in group 3a. Neither eta recognized fibrinogen. Purified fibrin monomer gave positive results with both EIAs. Detection of fibrinolysis by latex agglutination using monoclonal anti-DD resolves the problem of false positive results seen with polyclonal antifibrinogen in patients with liver disease. Elevated SFM in the absence of disseminated intravascular coagulation (DIC) in patients with liver disease may induce false positive ED results when measured by EIA.