Neutralization of Antithrombin VI (Fibrinogen Breakdown Products) with Platelet Antiheparin Factor (Platelet Factor 4)*

1965 ◽  
Vol 14 (03/04) ◽  
pp. 490-499 ◽  
Author(s):  
S Niewiarowski ◽  
R Farbiszewski ◽  
A Popławski
Keyword(s):  
Zinc Acetate ◽  
Antithrombin Iii ◽  
Platelet Factor 4 ◽  
Breakdown Product ◽  
Platelet Factor ◽  
Chromatography Column ◽  
Antiheparin Activity

SummaryIt has been found that fibrinogen breakdown product – antithrombin VI – is neutralized by the purified preparation of platelet factor 4, obtained by means of zinc acetate precipitation and DEAE chromatography column. It has been suggested that antiheparin activity of platelet factor 4 and its ability to neutralize antithrombin VI may be related to the same protein.The purified preparation of platelet factor 4 does not influence the fibrinogen – fibrin conversion by thrombin. This means that platelet factor 2 and platelet factor 4 are not the same substance.Crude platelet extracts neutralize antithrombin III and V. However, the purified product did not interferes with the action of these antithrombins.

Coagulation Disorders in Thrombocythaemia, a Study of Seven Cases

1962 ◽  
Vol 07 (01) ◽  
pp. 114-128 ◽  
Author(s):  
Stefan Niewiarowski ◽  
Halina Zywicka ◽  
Zbigniew Latałło
Keyword(s):  
Liver Parenchyma ◽  
Platelet Factor 4 ◽  
Coagulation System ◽  
Severe Bleeding ◽  
Clotting Factors ◽  
Platelet Factor ◽  
Antiheparin Activity ◽  
Thromboplastic Activity ◽  
Bleeding Episodes ◽  
Routine Coagulation

SummaryThe blood coagulation system has been studied in 7 patients with thrombocythaemia. 4 of these patients had thrombocythaemia after splenectomy, 2 of them had thrombocythaemia associated with myeloid leukemia, and 1 thrombocythaemia associated with polycythaemia. Severe bleeding episodes were noted in 5 cases, 2 patients had only mild bleeding symptoms.Each patient was examined several times. The period of observations varied from 2 months to 3 years. Platelet count varied from 350 000 to 3 800 000 per mm3.Bleeding time and tourniquet test were normal in all cases. Routine coagulation and fibrinolysis studies did not reveale characteristic abnormalities in plasma clotting factors. A decrease of prothrombin complex components was observed in 4 cases. This disturbance was due to the coexisting injury of liver parenchyma or myeloid changes but not to an increase of platelets or to the abnormalities in the platelet system.An increase of antiheparin activity was found in the plasma of 4 patients. This activity is probably due to the escape of platelet factor 4 from destroyed or qualitatively changed platelets into plasma.Platelet clotting factors were investigated in isolated platelet suspensions, A significant decrease of platelet factor 1 was observed in all patients and a decrease of platelet factor 4 in 5 patients. In 2 cases platelet factor 4 increased. Platelet thromboplastic activity showed a great variety of disturbances in conformity with other workers observations.Recent views on the pathogenesis of bleedings in thrombocythaemia are discussed. On the basis of their own investigations the authors suggest that the significant disturbances of platelet function may contribute to the development of bleeding, and that the increase of antiheparin activity in plasma may produce hypercoagulability and favorize the formation of thrombi.

NEUTRALIZING EFFECT OF PLATELET FACTOR 4 OR HISTIGINE-RICH GLYCOPROTEIN AGAINST LOW MOLECULAR WEIGHT HEPARIN AND UNFRACTIONATED HEPARIN

1987 ◽  
Author(s):  
K Takahashi ◽  
M Niwa ◽  
N Sakuragawa
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Antithrombin Iii ◽  
Platelet Factor 4 ◽  
Low Molecular Weight ◽  
Bleeding Tendency ◽  
Human Origin ◽  
Platelet Factor ◽  
At Iii ◽  
Antifactor Xa

Purpose: Low molecular weight(LMW) heparin shows stronger antifactor Xa(F-Xa) and weaker anti-thrombin(TH) activities compared with unfractionated(UF) heparin, and shows less bleeding tendency in the cases of clinical use. Platelet factor 4(Pf-4) and histidine-rich glycoprotein(HRG) neutralize heparin. We investigated on the heparin neutralizing effects of them to both kinds of heparinMaterials and methods: LMW heparin(Kabi and Pharmuka) and UF heparin(Novo) were used. Antithrombin III(AT-III), HRG(human origin ) and pf-4( bovine origin ) were purified by our methodsTH(Green-Cross) and F-Xa(Sigma) were used. Reaction mixtures for anti-TH or anti-F-Xa were as follows: 1 vol of AT-III( 0.1 U/ml)+ 1 vol of heparin( 10 ug/ml)+l vol of pf-4 or HRG(varied)→incubated for 5 min→+l vol of TH(5 U/ml) or F-Xa( 7 nKat/ml)→incubated for 5 min→ + S-2238 or S-2222→ recorded at 405 nm.Results: (1) Pf-4 showed the equivalent anti-TH effect on both kinds of heparin, and 3 ug of pf-4 neutralized 1 ug of heparinOn F-Xa neutralizing effect, 13 ug of pf-4 neutralized 1 ug of UF heparin, but could not neutralize LMW heparin. (2) HRG showed the same results on anti-TH effect of both kinds of heparin, but could not neutralize the anti-F-Xa effect of LMW heparin on the same amount of HRG which neutralized that of UF heparin. Conclusion: Anti-F-Xa effect of. LMW heparin could not be easily neutralized by pf-4 or HRG compared with that of UF heparin.

scholarly journals Dansyl (5-dimethylaminonaphthalene-1-sulphonyl)-heparin binds antithrombin III and platelet factor 4 at separate sites

1981 ◽  
Vol 196 (2) ◽  
pp. 649-651 ◽  
Author(s):  
Michael W. Piepkorn
Keyword(s):  
Antithrombin Iii ◽  
Platelet Factor 4 ◽  
Heparin Binding ◽  
Platelet Factor

Antithrombin III binds to, and thereby augments the fluorescence of, dansyl-(5-dimethylaminonaphthalene-1-sulphonyl)-heparin; platelet factor 4 binding to the fluorescent heparin has little of this effect. Competition studies in which antithrombin III competes with platelet factor 4 for heparin binding demonstrate that heparin can simultaneously bind both proteins.

Neutralization of the Antiheparin Activity of Platelet Factor 4 by a Monoclonal Antibody

1992 ◽  
Vol 67 (01) ◽  
pp. 137-143 ◽  
Author(s):  
Leopoldo Saggin ◽  
Flavia Cazzola ◽  
Giuseppe Corona ◽  
Emanuela Salvatico ◽  
Giuseppe Cella ◽  
...  
Keyword(s):  
Disulfide Bonds ◽  
Factor Xa ◽  
Human Platelets ◽  
Platelet Factor 4 ◽  
Molar Ratio ◽  
Rabbit Platelet ◽  
Platelet Factor ◽  
Chromogenic Assay ◽  
Antiheparin Activity ◽  
Human Molecule

SummaryWe have produced a panel of monoclonal antibodies (mAbs) against rabbit platelet factor 4 (PF4). Two of these mAbs have been characterized in this study. In particular the antibody called 10B2, which also recognizes the human molecule, is able to block PF4’s ability to neutralize heparin in a modified Heparin-Factor Xa chromogenic assay. The inhibition appears to be more than 95% at 1:1 mAb/PF4 molar ratio both for purified rabbit and human PF4. Similar results were obtained using supernatants from stimulated human platelets (90% of inhibition at 1:1 mAb/ PF4 molar ratio) or using Fab fragments from 10B2. Studies to determine the antigenic determinant against which 10B2 is directed, show that this is an assembled epitope which involves disulfide bonds of the PF4.

Critical Analysis of Platelet Factor 4 (Antiheparin Activity) Assays

1975 ◽  
Author(s):  
A. Hurlet ◽  
G. De Beys ◽  
M. Moriau ◽  
A. Monsieur ◽  
E. Schulzen ◽  
...  
Keyword(s):  
Calcium Chloride ◽  
Critical Analysis ◽  
Platelet Rich Plasma ◽  
Factor Xa ◽  
Platelet Factor 4 ◽  
Thrombin Time ◽  
Platelet Factor ◽  
Good Relationship ◽  
Antiheparin Activity ◽  
Set Up

Antiheparin activity is usually achieved by a heparin-thrombin time assay. Platelet free substrate plasma is adsorbed or not, calcium chloride used or not. Those technical conditions are analysed.Results are expressed by the amount of heparin units neutralized in the assay. With non adsorbed plasma substrate, calcium chloride generates thrombin, increasing antiheparin like activity. Lower antiheparin like activity is also observed with BaSO4 plasma substrate and with thrombin free of factor Xa. The amount of heparin units neutralized varies from 2.9 to 1.2 according to the system used.Tested without calcium, with Xa free thrombin and BaSO4 adsorbed substrate plasma, there exists a good relationship between the amount of heparin neutralized and various dilutions of serum, platelet rich plasma and platelet extract.An assay based on anti-Xa effect of heparin, set up according to the heparin assay of Yin, is compared to the method described above.

Problems In Measuring Low Dose Heparin

1981 ◽  
Author(s):  
R Róka
Keyword(s):  
Low Dose ◽  
Plasma Sample ◽  
Antithrombin Iii ◽  
Platelet Factor 4 ◽  
Platelet Factor ◽  
Individual Control ◽  
Dose Heparin ◽  
The Difference ◽  
Antithrombin Iii Activity ◽  
Low Dose Heparin

In order to assess the influence of low dose heparin on the reaction between thrombin and antithrombin, an individual control is needed, if heparin levels below 0,05 U/ml are to be measured. This allows discrimination between progressive antithrombin and heparin cofactor activity. The concentration of low dose heparin is calculated as the difference between spontaneous antithrombin III activity and progressive antithrombin III activity in a given sample. The plasma sample to be assayed also serves as individual control after heparin has been inactivated by binding to platelet factor 4. Purified platelet factor 4 can either be added to the sample or liberated from platelets contained in the sample by platelet sonification. The activity of progressive antithrombin in the control depends on the ratio of thrombin to antithrombin in the reaction mixture. This ratio and the activity of progressive antithrombin increase proportionally and thus influence the calculation of low dose heparin concentration. Comparable results are obtained only if this ratio is kept constant.

scholarly journals Isolation of the Antithrombin-Thrombin Complex and Platelet Factor 4 by Solid Phase Heparin

1977 ◽  
Author(s):  
H. Bleyland ◽  
L. Róka
Keyword(s):  
Blood Coagulation ◽  
Antithrombin Iii ◽  
Solid Phase ◽  
Platelet Rich Plasma ◽  
Divalent Cations ◽  
Platelet Factor 4 ◽  
Two Dimensional ◽  
Platelet Factor ◽  
Lower Affinity ◽  
Step Procedure

Solid-phase-heparin as heparin-agarose [Hep-Ag] was used for the isolation of the complex formed by antithrombin and thrombin. This complex has a lower affinity to heparin than antithrombin III. The complex has no antithrombin activity. The increase of the complex during blood coagulation can be seen by the two-dimensional Immunoelectrophoresis in agaroee, which contains heparin (Sas et al., Thromb.Res. 6, 87-91, 1975).Platelet factor 4 (PF 4) was isolated by a three step procedure: 1. precipitation by divalent cations according to Burstein, 2. adsorption to Hep-Ag and desorption with high salt concentrations, 3. desalting over Sephadex G 25 fine. PF 4 was prepared from isolated platelets, platelet rich plasma and serum.

scholarly journals Low Molecular Weight Heparin-Catalyzed Inactivation of Factor Xa and Thrombin by Antithrombin III – Effect of Platelet Factor 4

1991 ◽  
Vol 66 (04) ◽  
pp. 435-441 ◽  
Author(s):  
Pieter Schoen ◽  
Theo Lindhout ◽  
Jo Franssen ◽  
H Coenraad Hemker
Keyword(s):  
Molecular Weight ◽  
Rate Constants ◽  
Antithrombin Iii ◽  
Gel Filtration ◽  
Factor Xa ◽  
Platelet Factor 4 ◽  
Low Molecular Weight ◽  
Platelet Factor ◽  
International Standard ◽  
Molecular Weights

SummaryLow molecular weight (LMW) heparin preparations have unknown distributions of ATIII-binding material, so mean molecular weights as such might bear little information on their anti-factor Xa and anti-thrombin activities, and on the neutralization of these activities by platelet factor 4 (PF4). These properties were investigated in pure systems with proteins of human origin. Pseudo-first order rate constants of inactivation of factor Xa and thrombin by antithrombin III were determined as function of heparin concentration, in the presence of 4.0 mM CaCl2. Despite a large variation in the mean molecular weights, the ratios of the anti-factor Xa over the anti-thrombin activities were essentially the same for the 4th International Standard for heparin (0.46), the 1st International Standard for LMW heparin (0.32), CY216 (0.42) and enoxaparin (0.50). The ultra LMW heparin CY222 had only a 2-times higher ratio (0.98). Analysis of CY216 subfractions, obtained by gel filtration, showed that the heparin molecules of the upper region of the molecular weight distribution are responsible for the anti-thrombin, but also to a large extent for the anti-factor Xa activities. The results indicate that depolymerization of unfractionated heparin does not result in an increased anti-factor Xa/anti-thrombin ratio, because in the presence of Ca2+-ions the rate constants of inactivation of factor Xa are lowered as compared to those of native heparin. PF4-dependent neutralization of anti-factor Xa and anti-thrombin activities of fixed concentrations of the LMW heparins was studied by measuring rate constants as function of PF4 concentration. All anti-thrombin and 50% of the anti-factor Xa activities were readily neutralized. Excess PF4 was required to neutralize another 35-50% of the anti-factor Xa activities. At PF4 levels obtained at maximal release of the content of platelet α-granules, all anti-thrombin and most (≥85%) of the anti-factor Xa activities can be neutralized.

Sign in / Sign up

Export Citation Format

Share Document