The Influence of Serotonin on Clot Retraction and the Thrombelastogram

1958 ◽  
Vol 02 (01/02) ◽  
pp. 111-124 ◽  
Author(s):  
E Deutsch ◽  
K Martiny
Keyword(s):  
Human Plasma ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Specific Effect ◽  
High Dose ◽  
Clot Retraction ◽  
Platelet Counts ◽  
Essential Value ◽  
High Doses ◽  
Free Plasma

Summary1. Normal platelets are necessary for induction of normal clot retraction.2. Serotonin does not induce retraction in human platelet-free plasma-clots or enhance clot firmness as measured in the coagulogram.3. Serotonin does not improve clot retraction or firmness in plasma clots with sub-optimal platelet counts.4. Methylserotonin inhibits clot retraction of platelet-rich plasma to a certain extent in moderate doses, whereas, high doses are ineffective. BOL 148 has a similar, but less significant action. There is a possibility that these effects are specific antiserotonin-effects.5. LSD 25 was ineffective in all concentrations used.6. Largactil and reserpin inhibit retraction in high doses. There seems to be a non specific effect caused by the high dose.7. Reserpine does not release a retraction-inducing agent from the platelets, which could be detected in the centrifuged platelet-free plasma used for the incubation.8. Serotonin does not replace the retraction-cofactor of Hartert, or the dialyzable factor of Lüscher in synthetic clotting substrates.9. Serotonin is of no essential value in inducing normal retraction of human plasma clots.

Platelet-Bound Prekallikrein Promotes Pro-Urokinase-Induced Clot Lysis: A Mechanism for Targeting the Factor XII Dependent Intrinsic Pathway of Fibrinolysis

1994 ◽  
Vol 71 (03) ◽  
pp. 347-352 ◽  
Author(s):  
Jean-Pierre Loza ◽  
Victor Gurewich ◽  
Michael Johnstone ◽  
Ralph Pannell
Keyword(s):  
Platelet Rich Plasma ◽  
Specific Inhibitor ◽  
Specific Effect ◽  
Clot Lysis ◽  
Factor Xii ◽  
Intrinsic Pathway ◽  
Clot Retraction ◽  
Enzymatic Mechanism ◽  
Low Concentrations ◽  
Factor Xiia

SummaryClots formed from platelet rich plasma were found to be lysed more readily by low concentrations of pro-urokinase (pro-UK) than clots formed from platelet poor plasma. This was not a non-specific effect since the reverse occurred with tissue plasminogen activator. A mechanical explanation due to platelet-mediated clot retraction was excluded by experiments in which retraction was inhibited with cyto-chalasin B. Therefore, a platelet-mediated enzymatic mechanism was postulated to explain the promotion of fibrinolysis. Casein autography of isolated platelets revealed a ≈ 90 kDa band of activity which comigrated with plasma prekallikrein (PK)/kallikrein, a known activator of pro-UK. Furthermore, treatment of platelets with plasma PK activator (PPA), consisting essentially of factor XIIa, induced activation of pro-UK and of chromomgenic substrate for kallikrein (S-2302). This activity corresponded to approximately 40-200 pM kallikrein per 10 8 washed and gel filtered platelets per ml. The activation of pro-UK by PPA-pretreated platelets was dose-dependent and inhibited by soybean trypsin inhibitor but not by bdellin, a specific inhibitor of plasmin, nor by the corn inhibitor of factor XIIa. Kinetic analysis of pro-UK activation by kallikrein showed promotion of the reaction by platelets. The KM of the reaction was reduced by platelets by ≈ 7-fold, while the kcat was essentially unchanged. In conclusion, PK was shown to be tightly associated with platelets where it can be activated by factor XIIa during clotting. The activation of pro-UK by platelet-bound kallikrein provides an explanation for the observed platelet mediated promotion of pro-UK-induced clot lysis. Since pro-UK and plasminogen have also been shown to be associated with platelets, the present findings suggest a mechanism by which the factor Xlla-dependent intrinsic pathway of fibrinolysis can be localized and targeted to a thrombus.

Studies on the Thromboplastic Effect of Human Plasma Lipoproteins

1976 ◽  
Vol 35 (01) ◽  
pp. 178-185 ◽  
Author(s):  
Helena Sandberg ◽  
Lars-Olov Andersson
Keyword(s):  
High Density Lipoprotein ◽  
Human Plasma ◽  
Platelet Rich Plasma ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Plasma Lipoproteins ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Free Plasma ◽  
Good Agreement

SummaryHuman plasma lipoprotein fractions were prepared by flotation in the ultracentrifuge. Addition of these fractions to platelet-rich, platelet-poor and platelet-free plasma affected the partial thromboplastin and Stypven clotting times to various degrees. Addition of high density lipoprotein (HDL) to platelet-poor and platelet-free plasma shortened both the partial thromboplastin and the Stypven time, whereas addition of low density lipoprotein and very low density lipoprotein (LDL + VLDL) fractions only shortened the Stypven time. The additions had little or no effect in platelet-rich plasma.Experiments involving the addition of anti-HDL antibodies to plasmas with different platelet contents and measuring of clotting times produced results that were in good agreement with those noted when lipoprotein was added. The relation between structure and the clot-promoting activity of various phospholipid components is discussed.

Effect of Lidoflazine (R 7904) on Human Platelet Function in Vitro

1972 ◽  
Vol 28 (02) ◽  
pp. 228-236 ◽  
Author(s):  
F De Clerck
Keyword(s):  
Platelet Function ◽  
Mode Of Action ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Serotonin Release ◽  
Clot Retraction ◽  
Plasma Coagulation ◽  
Release Reaction ◽  
Platelet Release

SummaryThe effect of lidoflazine and of cinnarizine on human platelet function in vitro was compared to that of dipyridamole.Pre-incubation for 30 min at 37° C of platelet rich plasma with lidoflazine or with dipyridamole 5 ×10–4 M resulted in an appreciable inhibition of collagen aggregation in particular and to a lesser extent of ADP aggregation; cinnarizine was marginally active only.Clot retraction was inhibited by lidoflazine and by dipyridamole. Experiments on biphasic ADP aggregation and C14-serotonin release during aggregation show that lidoflazine reduces the platelet release reaction.The possible mode of action of the compound is discussed.Plasma coagulation and PF – 3 availability were not affected.

Thromboplastic Effects ot Human Plasma Lipoproteins

1975 ◽  
Author(s):  
L.-O. Andersson ◽  
H. Sandberg
Keyword(s):  
Human Plasma ◽  
Platelet Rich Plasma ◽  
Density Lipoprotein ◽  
High Density ◽  
Plasma Lipoproteins ◽  
High Density Lipoproteins ◽  
Phospholipid Content ◽  
Factor X ◽  
Promoting Effect ◽  
Free Plasma

Lipoprotein fractions from human plasma was prepared by ultracentrifugal flotation. Additions of those fractions to plasma containing various amounts of platelets showed that in platelet-poor and platelet-free plasma there was a clear clot-promoting effect of the additions. In platelet-rich plasma, this effect was negligible. Measurements on the thrombo-plastine and Stypven clotting times showed that the high density lipoprotein fraction affected both the prothrombin and the Factor X activation steps whereas the low density lipoproteins only influenced the prothrombin activation step. Addition of antibodies against high density lipoproteins to platelet-free plasma caused a prolongation of the thromboplastin time.The relation between lipoprotein structure, phospholipid content and thromboplastic effects is dicussed.

Montreal Platelet Syndrome (MPS):Ultrastructural, Biochemical And Functional Studies

1981 ◽  
Author(s):  
M M Frojmovie ◽  
J G Milton ◽  
S S Tang
Keyword(s):  
Platelet Count ◽  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Shape Change ◽  
Protein Profile ◽  
Peripheral Blood Smear ◽  
Ionophore A23187 ◽  
Clot Retraction ◽  
Platelet Counts

MPS is characterized by autosomal dominant inheritance thrombocytopenia (5,000-120,000 μl-1), abnormally large platelets on peripheral blood smear, spontaneous aggregation (SA), normal clot retraction and thromboplastin formation, nypervolumetric shape change and normal amounts of plasma membrane. Here we describe further characteristics of MPS for 3 siblings /5 affected family members. The ultrastructural features of MPS platelets were normal except for the high frequency of giant granules. Platelet aggregation (PA) was studied in citrated platelet-rich plasma at platelet counts of 5,000-40,000 μl-1 and was quantitated microscopically from the decrease in single platelet count. PA could be increased over that due to SA alone by the addition of ADP, adrenalin, collagen, ionophore A23187, arachidonic acid and ristocetin, suggesting that the response to these agents may be normal. The ristocetin-induced increase in PA was completely blocked by an IgG specific for BSS. In contrast, over a 4 year period, thrombin (0.2 units/ml) either did not or only slightly increased PA over SA for 3/3 donors. However, MPS platelets pelleted from ACD-PRP and resuspended in Tyrodes’, pH 7.4 at a platelet count of ~ 200,000 μ1-1 showed a normal response to thrombin by aggregometry. Only one donor’s platelets had both reduced sialic acid and glycoprotein (G.P.) 1 reduction/abnormality with otherwise normal G.P. and protein profile, while the other 2 siblings’ platelets showed no such abnormalities. The above results indicate that biochemical variability exists for MPS platelets from different affected siblings. Moreover, our observations raise the possibility that platelet aggregation abnormalities in thrombobytopenic disorders (may be obscured by (1) preparation artefacts and/or (2) artificially increasing platelet counts for in vitro studies.

scholarly journals PLATELET DISINTEGRATION DURING CLOTTING

1963 ◽  
Vol 16 (2) ◽  
pp. 225-241 ◽  
Author(s):  
N. F. Rodman ◽  
J. C. Painter ◽  
N. B. McDevitt
Keyword(s):  
Granular Material ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Blood Platelets ◽  
Clot Formation ◽  
Clot Retraction ◽  
Reaction Proceeds ◽  
Lag Period

Sequential alterations in the ultrastructure of blood platelets observed during the clotting of human platelet-rich plasma are described, with emphasis on disintegration of the platelet. As the clotting reaction proceeds, aliquots of citrated and recalcified citrated plasma are fixed by adding buffered OsO4. After recalcification a lag period of about 10 minutes is followed by an interval of rapidly occurring changes which include reorientation of cytoplasmic contents, progressive central degeneration, and disruption of the platelet limiting membrane. Shortly thereafter vesicular platelet remains are seen at the peripheries of loosely arranged and widely spaced masses of granular material. As clot retraction proceeds, these masses gradually come closer together, become more and more compact, and finally disappear. At the same time the vesicles undergo progressive disintegration until at the end of the experiment, 2 hours after recalcification, only a few are found randomly distributed in a dense clot. The significance of progressive disintegration and the origin of the vesicles observed in the later stages of the experiment are discussed in relation to clot formation and clot retraction.

scholarly journals The Platelet-Fibrin Relationship in Human Blood Clots: An Ultrastructural Study Utilizing Ferritin-Conjugated Anti-Human Fibrinogen Antibody

Blood ◽  
1965 ◽  
Vol 25 (2) ◽  
pp. 241-257 ◽  
Author(s):  
James G. White ◽  
William Krivit ◽  
Robert L. Vernier
Keyword(s):  
Human Plasma ◽  
Human Blood ◽  
Ultrastructural Study ◽  
Platelet Rich Plasma ◽  
Intracellular Distribution ◽  
Clot Retraction ◽  
Human Fibrinogen ◽  
Blood Clots

Abstract An ultrastructural study of clots formed in recalcified platelet-rich, human plasma has revealed an intimate platelet-fibrin association. A number of the dense platelet granules, the alpha granules, formed an osmophilic mass in the center of platelets undergoing viscous metamorphosis. Fibrin strands appeared to be connected to the altered alpha granulomere of these platelets. The observed association between fibrin strands and platelets in the clot was supported by experiments with an electron dense stain for fibrinogen. Clots formed from platelet-rich plasma preincubated with fer-A.F. antibody contained altered platelets with an intracellular distribution of the ferritin conjugated antibody. Connections between intracellular fer-A.F. antibody and fibrin strands periodically banded by the ferritin stain were observed. These observations indicate that the altered platelet granulomere attached to fibrin strands may play a role in clot retraction.

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