bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE IMPLEMENTATION OF THE WHO INTERNATIONAL NORMALISED RATIO (INR) SYSTEM OF PROTHROMBIN TIME STANDARDISATION
Authors: Poller L , Thomson J M , Taberner D A 
Published: August 2018

The implementation of the INR system has been assessed in a group of laboratories from over fifty countries. These centres participate in the World Health Organisation International Quality Control Programme in Blood Coagulation. Prothrombin times are performed on various lyophilised human coumarinised plasmas using both the local thromboplastin reagent and British Comparative Thromboplastin (BCT) reference preparation. During 1985 and 1986 a programme of education has been undertaken whereby instructions in the derivation of INR values have been given. The calculation of INR has been shown by means of a worked example and a chart for the conversion of the prothrombin ratio with BCT to INR was included. Prior to this, prothrombin results were expressed as British Corrected Ratios (BCR) with a minority of centres using INR. In 1984 the CV varied between 23.7% - 36.8% for results with local reagents, but between 8.2% - 14.3% with BCT. This suggested that conversion into INR/ BCR was unsatisfactory. The table shows the impact of the continuing educational programme.The number of laboratories expressing results as INR has steadily increased and the CV is now approaching that obtained with BCT. The improvement in CV suggests that the general application of the INR system will help improve inter-laboratory standardisation of oral anticoagulant control and should be encouraged.
ACUTE INTERRUPTION OF ORAL ANTICOAGULANT THERAPY: A THROMBOTIC RISK?
Authors: Rouvier J , Vidal H , Gallino J , Boccia M , Scazziota A , Altman R 
Published: August 2018

It is still on discussion how oral anticoagulant therapy must be interrupted. A progressive diminution of drug intake have been proposed in order to avoid a MreboundM of vitamin K-dependent procoagulant factors. At the present, it is well known that coumarin drugs affect not only the biologic activity of factors II, VII, IX and X but also Protein C (PC), an inhibitor of coagulation kinetics, and their cofactor Protein S. With the aim to determine the recovery level of PC in relation with the others vitamin K-dependent factors, the effect of suppression of anticoagulant therapy in patients under chronic treatment with acenocoumarin was studied.Quick time, functional factors II, VII, X (one stage methods), functional PC (Francis method) and immunological Factor II and Protein C (Laurell) were determined before and 36 hours after suspension of acenocoumarin administration.Results showed that: 1) Recovery levels of functional Protein C (increased from 28.55% ±2.57 to 72.64% ±5.9) were significantly higer than functional Factor II (22.09% ±2.34 to 30.73% ±8.64), Factor VII (22.55% ±2.01 to 40.73% ±4.85) and Factor X (23.27% ±2.66 to 39.18% ±3.19). Statistical analysis (Newmann-Keuls test) showed at least a p<0.01 between PC increase and factors II, VII or X increment.2) No significant differences were seen between immunological levels of Factor II before and after suspension of acenocoumarin.3) Levels of immunological PC in patients under anticoagulant therapy were higer than functional PC. After acenocoumarin suppression, not correlation was seen between immunological and functional Protein C recovery.It is concluded that acute suppression of acenocoumarin does not induce a thrombotic tendency because the recuperation of functional Protein C is more important than factors II, VII and X recovery.
COAGULATION, FIBRINOLYSIS AND PLATELET FUNCTION DURING COUMARIN THERAPY
Authors: Taberner D A , Thomson J M , Poller L 
Published: August 2018

The inactivation of factors VIII:C, V:C and fast acting TPA inhibitor by activated Protein C indicates that oral anticoagulation is more than simple reduction of prothrombin complex activity. To investigate these changes, six patients were studied after stopping oral anticoagulant treatment. Protein C activity and C antigen, Factors VIII:C, VIII:vWFAg, V:C, V:Ag, X:C, VII:C, fibrinogen and TPA activity were measured during long-term nicoumalone therapy (duration of therapy 8-96 months, mean 28 months), and after discontinuation on days 2, 4, 8, 10, 15, 30 and 42.The INR on the last day of therapy ranged between 2.0 - 3.3, (mean 2.6). Protein C activity and antigen and factor X became normal by day 8; factor II by day 10. Factor VII activity peaked on day 8, falling to resting levels by day 30. Factor VIII parameters remained high throughout, whereas Factor V antigen showed no significant change. Factor V activity was not quantifiable untill day 8 because of non-parallelism (? PIVKA effect), but was higher on day 8 than day 42 (p < 0.002 paired “t” test) . The higher levels of factor V activity could be protein C dependent, but the high factor VIII appears unrelated. Fibrinogen levels were higher on coumarin treatment (p < 0.05 paired “t” test) and took 30 days to fall to resting level. The effect of Protein C on TPA inhibitor would be expected to increase the activity of TPA, but this activity remained unchanged. Raised fibrinogen levels did not, therefore, appear to be mediated by the effect of protein C on fibrinolysis. Fibrinogen levels in plasma influence ADP induced platelet aggregation which is known to be increased in patients receiving coumarin drugs. In conclusion, patients on coumarin treatment, in addition to showing a reduction in protein C activity, also have higher fibrinogen levels and increased platelet aggregability all of which may be undesirable.
STOPPED-FLOW KINETICS OF PROTHROMBINASE COMPLEX ASSEMBLY
Authors: Krishnaswamy S , Jones K , Mann K 
Published: August 2018

Prothrombinase is the multi -component enzyme composed of factor Xa and the cofactor, factor Va, that assemble on a phospholipid surface in the presence of calcium ion. Fluoresence stopped-flow kinetic studies of prothrombinase assembly in the absence of the substrate, prothrombin were undertaken at saturating concentrations of calcium ion, using phospholipid vesicles (PCPS), factor Va and factor Xa modified at the active-site with the fluorophore dansyl-glutamylglycinylarginylchloro methylketone (DEGR-Xa). The substantial fluorescence enhancement of DEGR-Xa in the presence of factor Va, PCPS and calcium ion was used as a continuous measure of prothrombinase complex formation. The rate of complex formation studied under pseudo-first order conditions was most rapid when factor Va was reacted with the DEGR-Xa-PCPS binary complex. Under these conditions, the rate increased linearly with increasing PCPS concentrations and was independent of the concentration of factor Va. The reaction between Va and PCPS assessed by stopped-flow light scattering produced identical rates. The data indicate that the rate-limiting step in the reaction between Va and PCPS-bound DEGR-Xa is the initial formation of a Va-PCPS binary complex (8.4×107M−1s−1) followed by the very rapid reaction (>3×109M−1s−1) between PCPS-bound DEGR-Xa and Va. When complex formation was initiated by mixing DEGR-Xa and Va with PCPS or by mixing DEGR-Xa with Va-PCPS, the pseudo-first order rates were substantially lower. Under these conditions, increasing concentrations of factor Va inhibited the rate of prothrombinase complex formation which could be overcome by increasing PCPS concentrations. The data are consistent with the interpretation that the initial formation of the DEGR-Xa-PCPS complex is a prerequisite for prothrombinase assembly. The second order rate constant for the reaction between DEGR-Xa and PCPS (9.5×109M−1s−1 ) was independently determined by stopped-flow light scattering. Collectively, the data indicate that prothrombinase assembly proceeds via the initial formation of DEGR-Xa-PCPS and Va-PCPS binary complexes. The lipid-bound constituents then rapidly react via diffusion over the vesicle surface to form prothrombinase.(Supported by NIH grants HL-35058 and HL-34575)
REGULATION OF FACTOR V (FV) EXPRESSION IN HUMAN MEGAKARYOCYTES
Authors: Gewirtz A , shepiro C L , Bovd R , Colman R W 
Published: August 2018

We have suggested that synthesis of FY by human megakaryocytes (MEGS), is a maturation relrted event. This is based on our finding that when MEGS are cloned from progenitor cells in vitro in FY depleted medium, FY is immunochemically detectable only in morphologically recognizable (mature) cells (Blood 67:1639, '86). The stimuli which induce FY synthesis in MEGS are unknown, but if they are related or linked to factors which regulate terminal maturation processes cellular FY levels might increase as the maturation routine proceeds. To test this hypothesis, mature human MEGS were isolated from normal bone marrow by counterflow centrifugel elutrietion, deposited onto gloss slides by cytocentri-fugation, and then fixed in methanol:acetone. Individual cells were then staged, geometric meon cell diometer (size) determined with on opticol fylor, end FY end DNA levels measured. FV expression in a large area of the MEG (38 urn in diameter) was semi-quantitated by microspectrophotometry (MSPEC) using a sensitive Texas Red labeled streptavidin-biotin detection system and a monoclonal antibody probe (B10) directed against the non-binding FY activation peptide (150,000 kd). Cells were then reacted with Chromomycin A3 to allow for simultaneous DNA quantitation by MSPEC in the same cell. Correlation coefficients (r) and coefficient of determination [r2] were computer generated to discern potential relationships between FY expression, and MEG maturation stage, size or ploidy level in a total of 532 MEGS. Characteristics of the population, and r/r2 vs. MEG FV content ere shown below:r/r2 values did not significantly change when total MEG FY content was measured in 100 additional MEGS. Therefore, MEG FY levels varied independently with cell size and ploidy, and did not appear to correlate with degree of mature MEG maturation as determined by standard critera. In two of four preliminary experiments, low dose (8nM ql2h × 4 doses) tetradecanoyl phorbol acetate augmented both the number of MEGS expressing FV, and the level of FY expressed per individual cell. We conclude from these data that once FV synthesis is initiated, FY synthesis and events relating to final cell size and ploidy development are regulated independently. Our data also suggest that MEG FV synthesis may be regulated in part by the phosphoinositide-protein kinase C system.
THE IDENTIFICATION OF A NOVEL FACTOR X ACTIVATOR ACTIVITY IN Mg2+ - ANTICOAGULATED PLASMA
Authors: Saundry R H , Khumprayoon S , Savidge G F 
Published: August 2018

Mg2+ anticoagulated PPP (20mM MgCl2) was applied at RT to a Zn2+ immobilised biscarboxymethylamino Sepharose 4B column and eluted with 20mM Tris, 20mM MgCl2, 2.5mM CaCl2 0.15M NaCl buffer pH 7.4. Following collection of the wash-through fractions, bound proteins were developed through application of linear (0 to 35mM) imidazole gradients.All fractions were screened for F.II, V, IX, X, vWF:Ag, Protein C, Fg, Fn and 2-macroglobulin by ELISA, VIII:Ag by IRMA, and VIII:C by both 1-stage and 2-stage bioassay methods. VIIIrAg (60-90% yield), vWF:Ag (100%), VIII:C 1-stage activity (35%), Fn (> 60%), Fg (> 80%), V (50%) and a2-macroglobulin (> 70%) were located only in the gradient fractions. Two distinct peaks demonstrated shortening of the 2-stage VIII:C assay:- one co-eluting with the 1-stage VIII:C activity and another major peak in the wash-through fractions where antigenic determinants of F.II, IX, X and part of the protein C were located and partially resolved from each other. Only F.II.-Ag co-eluted with the “ 2-stage VIII:C” activity. Similar observations were found in Mg2+ -anticoagulated severe Haemophilia A plasma and in citrated PPP developed with 20mM MgCl2, 20mM Tris buffer. A1(0H)3 treatment abolished the activity from citrate -, but not from Mg2+ -anticoagulated plasma.The relevant fractions showed no activities in F.V, VII, VIII:C, IX or X 1-stage bioassays. They did not clot Fg and did not contain detectable Xa or Ila as assessed by S-2222, S-2238 or S-2288. Following incubation with specific antisera against IgG, II, V, VII:Ag, X, protein C, a- and g- lipoproteins, and plasminogen only anti-II inhibited this "2-stage VIII:C" activity. 2-stage VIII:C assays depend upon Ca2+ -dependent generation of Xa. Since the activity in the wash-through fractions could not be ascribed to VIII, Xa, or Ila the results would indicate the presence of a hitherto undescribed Factor X activator activity.
INHIBITION OF HUMAN FACTOR Xa BY ITS ACTIVATOR FROM RUSSELL’ S VIPER VENOM.
Authors: Latallo Zbigniew S , Jackson Craig M 
Published: August 2018

In contrast to bovine Factor Xa, human Factor Xa is inhibited by its activator from Russell’ s viper venom (X-CP). This inhibition occurs only in the presence of Ca ions. When Xa activity is measured using chromogenic substrates at pH 7.8, inhibition is more apparent at 37° C than 25° C, but can be reduced to nearly zero at high NaCl concentration. The extent of inhibition depends on the source of X-CP. X-CP isolated from Vipera russelli siamensis, which activates human Factor X with a K = 0.0187 ptt and Vmax of 5.26 x 10’ 11 M’ s-1 ([X-CP] 0.15 nM, 0.1 M NaCl, 0.01 M TRIS, 0.01 M HEPES, 5mM CaCl2, 0.1% PEG, pH 7.8, 25° C) inhibits the Factor Xa about twice as effectively as X-CP from Vipera russelli russelli for which the human Factor X activation rate is about half that observed with V. russelli siamensis. The inhibition is of a mixed type and results in doubling the apparent Km value and decreasing V by 20%. By fitting of the hyperbolic, mixed inhibition modelwhere E is human Xa, I is V. russellii siamensis X-CP, S is Cyclohexylglycyl-glycyl-arginine p-NA, the following values were calculated Km = 120 /xM, k, = 250 s’ 1, K. = 1.0 x 10"8, a = 2.0 and p = 0.82, (0.22 nM Xa, 0.1 M NaCl, 0.01 M TRIS, 0.01 M HEPES, 5 mM CaCl2 0.1% PEG pH 7.8, 25° C). Activation of human prothrombin by human Factor Xa as well as inhibition of the latter by antithrombin III are similarly affected by the binding of X-CP in the presence of Ca . X-CP binding to human Xa may explain some of the enigmatic differences in functional properties of bovine and human Factor Xa preparations.Supported by a Matching Grant from the American National Red Cross and by the S.E. Michigan Red Cross Blood Service
REDUCED β-FXIIa-INHIBITION CAPACITY IN KEPARINIZED PLASMA SAMPLES.
Authors: Fuhrer G , Gallimore M J , Heller W , Hoffmeister H E 
Published: August 2018

It has been shown by our group that B-FXIIa-inhibi-tion was reduced in platelet rich plasma. To investigate the effect of heparin on B-FXIIa-inhibition, kallikrein inhibition and C1-esterase inhibition high and low molecular weight heparin preparations were added to plasma samples. Using high molecular weight heparin from 0 to 5 anti Xa/ml a reduction in B-FXIIa-inhibition was seen from 103% to 59%.These effects were abolished by the addition of protamine chloride. No changes of kallikrein inhibition and C1-esterase-inhibition were observed in heparinized plasma samples After the addition of a low molecular heparin preparation to plasma samples, the reduction of B-FXIIa-inhibition was markedly decreased. The levels of the Hage-man fragment inhibitor capacity were lowered to 22% compared to initial values of 91%. The antagonization of heparin normalized these values. No reduction in kallikrein inhibition and C1-esterase inhibition were found in these samples because in all three assays C1-inhibitor activity is analysed, purified C1-inhibitor was added to buffer containing several heparin concentration ( see table )These results suggest that the inhibition of B-FXIIa is markedly affected by heparin whilst no changes were seen in the inhibition capacity for C1-esterase and kallikrein.
HAGEMAN TRAIT INVESTIGATED BY FACTOR XII cDNA PROBES
Authors: Volinia S , Patracchini P , Vannini F , Felloni L , Panicucci F , Beranardi F 
Published: August 2018

The presence of gene lesions and of restriction fragment length polymorphisms (RFLPs) has been investigated by means of cDNA probes for the coagulation factor XII (FXII).A TaqI additional fragment (2.1Kb) has been found in two brothers with Hageman trait and in 11 members of their paternal lineage. Digestions with different enzymes exclude that FXII gene deletion is responsible for Hageman trait in this family. A point mutation originating an additional TaqI site is likely.The abnormal pattern (not present in 40 normal subjects) is correlated with a reduced FXII activity and identifies the heterozygous subjects in the paternal lineage. The presence of two different gene lesions causing Hageman trait in this family can be inferred.The TaqI additional site has been mapped within the 5 portion of the gene.Data suggest the presence of one FXII gene per aploid genome and disagree with previous localization of FXII gene on chromosome 6.Work supported by P.F. Ing. Gen. e Basi Mol. Mai. Ered. contratto CNR N.8400877
POST-OPERATIVE CHANGES IN FACTOR XIII and FIBRCNETITN
Authors: Reintz M , Sauer H , Witzke G , Neher M 
Published: August 2018

Wound healing processes after surgery are not restricted to certain areas tut affect the vhole body; the ooagulaticn systan in particular is involved. We studied Factor XIII and fibrcnectin in the blood plasma of 16 patients before surgery, after surgery and cn the 1st, 3rd and 7th days after surgery; fibrcnectin was determined using IC-Partigen iimunodiffusicn and Factor XIII by Behringwerke rapid test. In 11 patients normal wound healing was observed (group A), while in 5 patients explications oocured (group B). Factor XIII: normal group (A): fall in concentration oenpared with the precpera-tive value up to the 7th day after surgery; group with explications (B): fall in concentration more pronounced than in the normal group up o the 7th day after surgery.Fibrcnectin : Normal group (A): Fall in concentration ocpared with the precperative value up to the 1st day after surgery, followed by a rise in concentration; group with ocplicaticns (8): fall in concentration more marked than in the normal group, less marked rise in concentration than in the normal group. Duplications in wound healing were characterized by an increased fall in Factor XIII and fibrcnectin.
QUANTIFICATION OF FACTOR XIIIa-MEDIATED FIBRIN CROSSLINKING USING HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY-BASED IDENTIFICATION OF CROSSLINKED γ-CHAINS AND γ-CHAIN COMPONENTS.
Authors: Kiso U , Kaudewitz H , Henschen A 
Published: August 2018

Factor XIIIa catalysis the formation of isopeptide bonds in fibrin vhereby first and quickly the C-termini of two γ-chains in adjacent molecules are crosslinked and then much more slowly several a-chains. The crosslinking sites of the γ-chain are well-known, but those of the a-chain still only tentatively and partially identified. The crosslinking reaction has previously usually been monitored by sodium dodecylsulfat-polyacrylamide gelelectrophoresis (SDS-PAGE) of the mercaptolysed fibrin or fibrin degradation products. More recently, specific antibodies against the crosslinked γ-chain region have been produced which allow immunological assays for crosslinking products, i.e. for D-dimer.The present study deals with novel, high-performance liquid chromatography (HPLC)-based procedures for the identification and quantification of crosslinked γ-chains or γ-chain products. The degree of crosslinking was determined by quantifying the dimer either of the total γ-chain or of its C-terminai cyanogen bromide fragment. For this propose factor Xllla-containing fibrinogen was incubated with thrombin in the presence of calcium ions and cysteine. The reaction was interrupted by the addition of a urea-mercaptoethanol solution after various periods of time and the samples analysed in parallel by reversed-phase HPLC and SDS-PAGE. In both systems the steady decrease first in γ- and then in a-chain and simultaneous increase in γ-chain dimer was observed. The dimeric γ-chain appeared as a well separated and defined peak on HPLC. In the alternative approach crosslinked fibrin, fibrin degradation products or γ-chain were first cleaved by cyanogen bromide and then the resulting fragments were analysed by reversed-phase HPLC. Also here a characteristic component appeared which was identified by sequence analysis as the dimeric C-terminal fragment of the γ-chain and which only was present in crosslinked material.
POLYMERIZATION OF FIBRINOGEN AND FIBRONECTIN CATALYZED BY FACTOR XIII.
Authors: Procyk R , Block M , Blomback B 
Published: August 2018

Factor XIII catalyzed the formation of gels in solutions containing physiological concentrations of fibrinogen and fibro-nectin. Oligomeric intermediates were isolated from reaction mixtures at early times prior to gel formation by chromatography on gelatin-Sepharose and by FPLC using Superose 6 columns. The products of two simultaneous polymerization reactions were characterized: fibrinogen oligomers (fibrinogenin) from the poly merization of fibrinogen, and conjugates of fibrinogen-fibro-nectin (heteronectin) from heteropolymer formation involving the two proteins.At a constant concentration of fibrinogen (2.5 mg/mL) and factor XIII (0.4 U/mL), the appearance of different sizes of fibrinogen polymers depended on the concentration of fibronectin added to the reaction mixture. At fibronectin concentrations in the range of the normal plasma level of 0.3 mg/mL, fibrinogen formed oligomers of various sizes up to heptamer before incorporating a molecule of fibronectin. At a high fibronectin concentration (3.2 mg/mL) most of the fibrinogen reacted with the fibronectin at the monomer stage, although small amounts of fibrinogen dimers and trimers were also formed.Heteronectin formation coincided with the appearance of filamentous and particulate matter. This material became incorporated into a gel structure if sufficient fibrinogen was present in the reaction mixture (about 0.5 mg/mL). If these factor XIII catalyzed polymerization reactions occur in the microvasculature under conditions where the fibrinogen concentration might be significantly lowered, the production of fibrinogen-fibronectin polymeric material without gel formation would be favored.