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Results for “Platelet Factor 3”

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At least 19 recordsLinked to original sources
PubMed1976

Activation of platelets by platelet activating factor (PAF) derived from IgE-sensitized basophils. IV. PAF does not activate platelet factor 3 (PF3).

Platelet activating factor (PAF) derived from antigen-stimulated, IgE-sensitized rabbit basophils acts on platelets to induce aggregation and secretion of their content of granule-bound vasoactive amines. Despite this, PAF did not activate platelet factor 3. In contrast, collagen induced aggregation, secretion and PF3 activation in the washed platelets. Other stimuli (ADP, C3b, thrombin) also initiated both secretion and PF3 activation. A wide dose range of PAC, including those giving maximal secretion and aggregation, were ineffictive in making PF3 available and the possibility that PAF inhibited PF3, or its generation, was also excluded. It is concluded that PAF is a unique stimulus for platelets and that secretion and aggregation are not necessarily accompanied by PF3 generation.

Animals↗
PubMed1977

The effect of phospholipase C on platelet factor 3 in human blood platelets.

Intact human platelets isolated by gel filtration have been treated with purified phospholipase C. The effect of the enzyme on available and total platelet factor 3 has been tested. The available procoagulant platelet factor 3 was very low. A further small reduction was observed after incubation with phospholipase C when the enzyme was washed away before testing. External attack on platelets by phospholipase C led to a marked inactivation of total platelet factor 3.

Blood Coagulation Factors↗
PubMed1975

Platelet activity ratio. A new approach for quantitation of platelet factor 3.

The ratio of kaolin recalcification time in platelet-poor plasma to kaolin recalcification time in platelet-rich plasma appears to provide a more accurate estimate of platelet factor 3 activity than measurement of kaolin recalcification time in platelet-rich plasma alone. This ratio is termed the "platelet activity ratio." Over a fairly wide range the platelet activity ratio appears to follow a linear log-log relationship to platelet count (platelet counts of 12,500 to 200,000). The use of diluted platelet substitute as artificial standard greatly simplifies preparation of (1) standard curves and (2) quality control plasmas. If platelet activity ratio is expressed as a percentage of normal platelet factor 3 activity, the normal range for "total" platelet factor 3 (PF3t) is 60 to 175% and normal range for "available" platelet factor 3 (PF3a) is 14 to 47%.

Blood Coagulation↗
PubMed1976

Anti-platelet antibody determination by platelet factor 3 assay.

Anti-platelet antibody determinations by a recently introduced platelet factor 3 assay (Pf-3 assay) were evaluated in 159 specimens from 95 patients who had low platelet counts. As a standard procedure, the 51Cr lysis test (51Cr test) was used. The 51Cr test and Pf-3 assay had an excellent correlation (results agreed for 80.5% of 159 specimens tested). Overall positive results for the 159 specimens were 27.7% by the 51Cr test and 22.0% by the Pf-3 assay. A significantly high incidence of anti-platelet antibodies (71.4%) was found in patients who had received more than 10 units of blood transfusions, in contrast to a non-transfused group, which had an incidence of 6.3%. The difference between transfused and non-transfused groups was significant (x2 = 11.854, p less than 0.001). The Pf-3 assay is easy to perform in most laboratories and yet sensitive enough to detect anti-platelet antibodies that were detectable by the 51Cr test.

Adult↗
PubMed1975

[The determination of platelet factor 3 using hirudin].

The influence of blood platelets on the recalcification time under hirudin was investigated. Contrary to the investigations of whole-blood which reveal a pathological prolongation of the hirudin tolerance test only at platelet numbers under 30,000/mug, a change of the recalcification time under hirudin could also be found in the plasma at higher platelet numbers. The recalcification time increased inversely proportionally with falling platelet number. The shortening of time in platelets rich plasma attributed to the activity of platelet factor 3. Differences in the examinations of whole-blood may be attributed to an erythrocyte activity similar to factor 3. The application of hirudin for determining platelet factor 3 is recommended as a sensible method easily to be performed in practice.

Blood Coagulation Factors↗
PubMed1976

A standardized bioassay for platelet factor 3 released by kaolin.

The test for platelet factor 3 described by Hardisty & Hutton (1975) has been modified to conform to the usual design for a parallel-line bioassay. Manchester Comparative Thromboplastin has been used as assay Standard, allowing an arbitrary unit of activity to be adopted. However, experiments suggested that the platelet activity measured was different from tissue factor activity. Platelets are tested as platelet-rich plasma diluted in a standardized mixture of plasma and fibrinogen, so that differences between the clotting factors of the test samples are eliminated, as verified by experiments on haemophiliacs and patients on anticoagulant treatment. Sonication and repeated freezing and thawing of platelet-rich plasma showed that approximately 15% of the PF3 is released by kaolin. In vivo, a single dose of 600 mg of aspirin reduced the PR3-release to half the previous value in 2 h; initial values were regained in 5-8 days.

Anticoagulants↗
PubMed1976

Distribution of phospholipids, fatty acids, and platelet factor 3 activity among subcellular fractions of human platelets.

As compared with other methods, our recently reported method for subcellular fractionation of human platelets improves the separation of mitochondria, alpha granules, and lysosomal enzyme activities. The relative purity of these fractions has led us to undertake the present study to compare the subcellular distribution of phospholipids, fatty acids, and platelet factor 3 (clot-promoting) activity. Two findings pertaining to distribution of phospholipids were entirely new. (1) In the alpha granule zone, plasmalogen phosphatidyl ethanolamine peaked at the expense of diacyl phosphatidyl ethanolamine. (2) The fatty acid composition of the membrane lysophosphatidyl choline suggested that it may have been formed by the action of platelet phospholipase A2 activity. The fatty acids of the membranes showed a markedly asymmetrical distribution in noncholine versus choline phospholipids. The latter held 94%, 72%, and 85%, respectively, of the total content of 16:0, 18:1, and 18:2 fatty acids, whereas 55% of the 18:0, 72% of 20:4, and 67% of higher polyenoic acids other than 20:4 were esterified to the noncholine group. The most important new information related to clot-promoting activity, which, on the basis of protein content, was highest in the membrane fractions, but on the basis of phospholipid content in the nonmembranous fractions. The discussion centers on possible explanations for this novel finding.

Blood Coagulation Factors↗
PubMed1977

The problem of platelet autoantibodies. I. Evaluation of the platelet factor 3 availability test for their detection.

To assess two modifications of the platelet factor 3 (PF3) test for platelet antibody detection, an analysis of test conditions was performed with normal test material (serum, plasma, globulin fraction), defined HLA-specific, complement-fixing antisera and a quinidine-induced antiserum. It was shown that, under standardized conditions, the PF3 test revealed known platelet antibodies confirming earlier results. Its reproducibility and, to a lesser degree, its sensitivity were inferior to platelet complement fixation. In contrast, the test did not permit the reliable determination of platelet autoantibodies in sera of 89 thrombocytopenic patients including 36 cases of idiopathic thrombocytopenic purpura. Positive results loosely corresponded to the presence of HLA antibodies in sera.

Autoantibodies↗
PubMed1979

[Blood serum antiplatelet activity in acute leukemia and idiopathic thrombopenia studied with the aid of the platelet factor 3 availability test].

The effect of the activity present in the globulin fraction of the serum of patients with acute leukaemias and thrombocytopenia on the isologous platelets was investigated. This activity caused, due to increased availability of platelet factor 3, an acceleration of the endogenous clotting pathway with resulting shortening of the clotting time in the test of platelet factor 3 availability. This test was done in 44 patients with acute leukaemia and 19 with thrombocytopenia demonstrating a high-grade shortening of the clotting time as compared with that in a group of 30 healthy controls. In some cases of complete remission of acute leukaemia an effect of this activity on the autologous platelets was demonstrated. The antiplatelet activity was inhibited by rabbit serum against human IgG and Fc fragment of the heavy chain in IgG. These results suggest that the activity present in the globulin fraction of the serum may be one of the causes of thrombocytopenia in acute leukaemia.

Acute Disease↗
PubMed1978

Experience of a platelet factor 3 immunoinjury technique in the detection of antiplatelet antibody in systemic lupus erythematosus and other clinical disorders.

Using a recently described platelet factor 3 (PF3) immunoinjury technique designed for the detection of antiplatelet antibody, sera from 62 patients were analysed. 30 of the subjects had systemic lupus erythematosus and the remaining 32 had other clinical disorders. Platelet survival studies were also carried out in every subject. The PF3 test proved positive in 10 of our patients. However, only 1 of these 10 subjects had shortened platelet survival. It is concluded that the PF3 test does not appear to be of use in the detection of circulating antiplatelet antibody.

Adolescent↗
PubMed1976

Impairment of platelet adhesiveness and platelet factor 3 activity in cyanotic congenital heart disease.

In 33 children with cyanotic congenital heart disease the platelet function has been studied. The most significant changes were reduced platelet adhesiveness to glass and impaired availability of platelet factor 3 in nearly 50% of the patients. Although clot retraction was poor in 84% of them, thrombocytopenia and prolonged bleeding time were not significant features.

Blood Coagulation Factors↗
PubMedDate not supplied

Platelet antibody determination by platelet factor 3 assay (comparison with radiolabelled serotonin release and platelet aggregometry).

Platelet antibody determination by the PF3 test was carried out in 96 thrombocytopenic patients with various disorders, 31 repeatedly transfused patients with or without thrombocytopenia and 24 patients with autoimmune disease (SLE and myasthenia gravis) without thrombocytopenia. The frequency of a positive test was greatest in the patients with ITP (61%), SLE (50%) or a history of numerous blood transfusions (60%). The patients with myasthenia gravis also showed a considerable frequency (20%) of platelet antibodies detectable by the PF3 test. The PF3 test is less sensitive than the serotonin release test in detecting autoantibodies, but it is more sensitive than aggregometry in detecting isoantibodies and drug-related antibodies.

Autoantibodies↗
PubMed1977

The platelet factor 3 immunoinjury technique re-evaluated. Development of a rapid test for antiplatelet antibody. Detection in various clinical disorders, including immunologic drug-induced and neonatal thrombocytopenias.

A modified version of the platelet factor 3 immunoinjury technique for the detection of antiplatelet antibody is described in detail; heat-inactivated sera and frozen platelets are employed. The modification allows the results of the test to be available within 4 to 5 hours after drawing the blood sample, in contrast to the 3 days required in the original method. The technical work involved is significantly reduced. The reproducibility of the technique is improved. Results obtained with the two tests correlate well. Data accumulated in 458 cases of clinical disorders associated with antiplatelet antibody are reported. Drug-dependent antiplatelet antibody was demonstrated in 26 cases of thrombocytopenia associated with 19 different drugs. Data are also presented for 23 cases of neonatal thrombocytopenia.

Autoantibodies↗
PubMed1992

Development of a new method for detection of platelet factor 3 like activity.

We asked the question, "Can thalassemic erythrocytes play some role in alteration of the hemostatic system?", because clinical examination of thalassemic patients shows symptoms and signs related to alterations in hemostatic and circulatory systems, and thalassemic erythrocytes are different from normal erythrocytes. We obtained one of the answers to the question: The erythrocytes of postsplenectomized patients of beta-thalassemia/HbE disease could stimulate their own platelets to aggregate spontaneously. To know the role of erythrocytes in platelet aggregation, we wanted to examine the effect of thalassemic erythrocytes on the coagulation system by focusing of PF3-like activity of erythrocytes, because PF3-like activity of the ghosts of erythrocytes had been reported. For the study, we tried to develop a technique that was accurate and sensitive enough to detect PF3-like activity of blood. The system we developed was the following: 1) We activated the intrinsic coagulation pathway of commercial standard plasma by ellagic acid. 2) CaCl2, a fixed amount of PF 3 and synthetic thrombin inhibitor MD 805 were added to the reaction mixture. 3) At a fixed time, thrombin activity in the mixture was measured by using S-2238 as a substrate. At full activation of the contact system by ellagic acid, the amount of thrombin formed in a certain time depended on the amount of PF3-like substances such as cephalin, freeze-thawed platelets or ghosts of erythrocytes added to the test system, indicating that PF3-like activity of those substances can be measured by the activity of thrombin generated in a fixed time.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Coagulation Tests↗