Responses of Platelets to Strains of Streptococcus sanguis: Findings in Healthy Subjects, Bernard-Soulier, Glanzmann’s, and Collagen-Unresponsive Patients

1987 ◽  
Vol 57 (02) ◽  
pp. 222-225 ◽  
Author(s):  
A H Soberay ◽  
M C Herzberg ◽  
J D Rudney ◽  
H K Nieuwenhuis ◽  
J J Sixma ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Healthy Subjects ◽  
Normal Subjects ◽  
Membrane Glycoprotein ◽  
Response Mechanism ◽  
Platelet Response ◽  
Induce Platelet Aggregation ◽  
Streptococcus Sanguis ◽  
Lag Times ◽  
Bernard Soulier Syndrome

SummaryThe ability of endocarditis and dental strains of Streptococcus sanguis to induce platelet aggregation in plasma (PRP) from normal subjects were examined and compared to responses of PRP with known platelet membrane glycoprotein (GP) and response defects. S. sanguis strains differed in their ability to induce normal PRPs to aggregate. Strains that induced PRP aggregation in more than 60% of donors were significantly faster agonists (mean lag times to onset of aggregation less than 6 min) than those strains inducing response in PRPs of fewer than 60% of donors.Platelets from patients with Bernard-Soulier syndrome aggregated in response to strains of S. sanguis. In contrast, platelets from patients with Glanzmann’s thrombasthenia and from a patient with a specific defect in response to collagen were unresponsive to S. sanguis. These observations show that GPIb and V are not essential, but GPIIb-IIIa and GPIa are important in the platelet response mechanism to S. sanguis. Indeed, the data suggests that the platelet interaction mechanisms of S. sanguis and collagen may be similar.

scholarly journals New Method for Assessment of Plasma Von Willebrand Factor

1977 ◽  
Author(s):  
T. Sano ◽  
T. Motomiya ◽  
N. Mashimo ◽  
H. Yamazaki
Keyword(s):  
Platelet Aggregation ◽  
Von Willebrand Factor ◽  
Platelet Rich Plasma ◽  
Normal Subjects ◽  
Induce Platelet Aggregation ◽  
Platelet Suspension ◽  
Maximal Plasma ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Diabetes Melitus

As much interests have been focused on von Willebrand factor (vWF) in diabetes melitus and atherosclerosis, request to determine vWF has been increasing recently. Two methods for assessment of plasma vWF level, without platelet aggregometer, were devised. 1) Platelet-rich plasma (PRP) sensitivity to ristocetin-induced platelet aggregation (RIPA): PRP was separated without centrifugation from citrated blood. Serially two-fold diluted restocetin (16 to 16x2-10 mg/ml) was prepared in a Cooke Microtiter tray and PRP (25 μl each) was added to each concentration of ristocetin. Then the ristocetin-PRP mixture was agitated for 15 seconds using a Kowa Kizai Micromixer and the minimum effective final concentration of ristocetin to give platelet aggregation was obtained microscopically and this was defined as PRP sensitivity to RIPA. This method is convenient for screening test. 2) vWF assay:Serially two-fold diluted plasma (2 to 1024 times, in Tris-salin pH 7.2 containing 12 mg/ml bovine serum albumin), fixed and washed platelet suspension (6x105 /μl, Macfarlane et al.1975) and 3 mg/ml ristocetin were mixed (25 μl each) in a microtiter tray and agitated for 15 seconds. The maximal plasma dilution to induce platelet aggregation was obtained microscopically and defined as the titer of plasma vWF. In normal subjects, minimum effective ristocetin concentration (PRP sensitivity to RIPA) was around 1 to 0.5 mg/ml and maximal plasma dilution to give platelet aggregation (vWF titer) was around 16 to 32 times. The present methods have a good reproducibility and are performed easily without aggregometer and thought to be useful clinically.

Human Anti-Streptokinase Antibodies Induce Platelet Aggregation in an Fc Receptor (CD32) Dependent Manner

1995 ◽  
Vol 74 (03) ◽  
pp. 938-942 ◽  
Author(s):  
Jamal Lebrazi ◽  
Gérard Helft ◽  
Mustapha Abdelouahed ◽  
Ismaïl Elalamy ◽  
Massoud Mirshahi ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Response Curve ◽  
Human Platelets ◽  
Antibody Concentration ◽  
Dependent Manner ◽  
Platelet Response ◽  
Induce Platelet Aggregation ◽  
Fibrinogen Binding ◽  
Two Factors ◽  
Unimodal Response

SummaryExposure to streptokinase (SK) elicits anti-SK antibodies (Abs), which inhibit fibrinolysis and induce platelet aggregation. The mechanism of the latter is not fully understood, although it seems to involve platelet binding by a plasminogen streptokinase and anti-SK ternary complex. Anti-SK Abs were purified by affinity chromatography from serum of patients having received SK for acute myocardial infarction (AMI), and were shown to be of the IgG type. Their effects were studied with (i) human platelets in citrated plasma in the presence of SK or acetylated plasminogen-SK activator complex (APSAC), and (ii) in washed platelets, resuspended in Tyrode buffer after lowering the ionic strength, in the presence of APSAC (which provides both SK and plasminogen). An antibody concentration-response curve was obtained, showing a plateau in the presence of 0.1 mg/ml IgG. By increasing the concentration of APSAC, we obtained a unimodal response curve, the optimal concentration of APSAC being 0.05 U/ml. Aggregation was suppressed by chelating calcium with EDTA, blocking fibrinogen binding by the synthetic peptide Arg-Gly-Asp-Ser (RGDS), and raising intraplatelet cAMP with Iloprost (a prostacyclin analogue). Aggregation required the interaction of the anti-SK Ab Fc domain with the platelet Fc-gamma receptor type II, also known as CD32, since: (i) it was blocked by the monoclonal antibody IV-3 directed against CD32, (ii) it did not occur with F(ab)’2 fragments, which block the response to the intact IgG. The clinical relevance of these platelet-activating anti-SK antibodies remains to be determined. Two factors might influence clinical outcome: (i) the amount and type of pre-existing anti-SK Abs; (ii) the known interindividual variability of the platelet response to binding and activation by IgG involving the CD32 molecule.

CHEMICAL CROSS-LINKING OF HUMAN THROMBIN TO PLATELET MEMBRANE GLYCOPROTEIN Ib

1987 ◽  
Author(s):  
M Jandrot-Perrus ◽  
D Didry ◽  
M C Guillin ◽  
A T Nurden
Keyword(s):  
Cross Linking ◽  
Lag Phase ◽  
Membrane Glycoprotein ◽  
Platelet Response ◽  
Platelet Surface ◽  
Crossed Immunoelectrophoresis ◽  
Human Thrombin ◽  
Chemical Cross Linking ◽  
Short Incubation Time ◽  
Bernard Soulier Syndrome

The interaction of thrombin with proteins at the platelet surface was assessed by chemical cross-linking with the membrane impermeable reagents DTSSP and BS3. Washed platelets were incubated with 125I-α-thrombin, 125I-TLCK-inactivated α-thrombin or 125I-γ-thrombin, and then with 0.1 mM DTSSP or BS3. The pattern of 3H-labeled glycoproteins (GP) was only slightly modified, with no measurable loss of GPIb, lib, Ilia, V and IX. Thrombin was detected in high molecular weight complexes migrating at the top of a 3 % acrylamide stacking gel and at the tap of the separating gel (7 %). In addition, a complex of Mr : 240 000 has been characterized. This complex was formed with 0.5 to 50 nM thrombin, after a short incubation time (30 sec) with active thrombin as well as with TLCK-thrombin. Hirudin added in excess before the crosslinker inhibited its formation. After analysis of soluble extracts by crossed Immunoelectrophoresis against a rabbit anti-whole platelet serum, 3 precipitates were labelled, among them the GPIIb-Illa complex and the most intense, a precipitate in the position of GPIb. Immunoprecipitation of GPIb using a murine monoclonal antibody allowed the isolation of the 240 000 complex. This complex was not observed with platelets from a patient with the Bernard-Soulier syndrome or with chymatrypsin-treated platelets lacking the outer portion of the GPIb αchain. 1125I-γ-thrombin was unable to bind to GPIb and form sucha complex. In each of these three examples of a defective binding, of thrombin toGPIb, the pattern of platelet aggregation and release reaction are characterized b a prolonged lag phase. Our results confirm the ability of GPIb to bindα-thrombin and support a role for this interaction in governing, the velocity of the platelet response.

Comparative Effects of Recombinant Staphylokinase and Streptokinase on Platelet Aggregation

1997 ◽  
Vol 77 (05) ◽  
pp. 0815-0817 ◽  
Author(s):  
Mustapha Abdelouahed ◽  
Mohamed Hatmi ◽  
Gérard Helft ◽  
Sharareh Emadi ◽  
Ismaïl Elalamy ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Thrombolytic Agent ◽  
Marked Decrease ◽  
Platelet Rich Plasma ◽  
Fibrinogen Concentration ◽  
Platelet Response ◽  
High Concentration ◽  
Induce Platelet Aggregation ◽  
Platelet Aggregation Defect ◽  
Very High

SummaryRecombinant staphylokinase (RSTA) has been shown to offer promise as a thrombolytic agent. In contrast to streptokinase (SK), few studies have been devoted to possible effects of RSTA on platelets. We have compared the capacity of RSTA and SK to trigger platelet aggregation and to modify ADP (2.5 µM) response in platelet-rich plasma (PRP) of 25 healthy subjects. Thus, exposure of PRP to SK (40 to 50 µg/ml) induced platelet aggregation in 6 out of 25 subjects. However, under the same conditions, RSTA failed to induce platelet aggregation in all cases (25 out of 25 subjects). In contrast to RSTA, SK (0.4 to 50 µg/ml) greatly reduced ADP-induced platelet aggregation in 12 out of 25 subjects. Preincubation of plasma with SK is associated with a decrease in the fibrinogen concentration. Furthermore, there was a good correlation between SK-induced fibrinogenolysis and SK- induced platelet aggregation defect (r2 = 0.9; p = 0.001). No fibrino genolysis was observed when different amounts of RSTA (0.4 to 50 µg/ml) were incubated in plasma for one min. However, there was a marked decrease in fibrinogen level (about 50%) when the plasma was incubated for five min with a very high concentration of RSTA. SK markedly enhanced the platelet response to ADP in 13 out of 25 subjects. In PRP of 6 out of 25 subjects, SK induces platelet aggregation and potentiates platelet response to ADP, however in PRP of 7 out of 25 subjects, SK caused only the increase of platelet response to ADP. The monoclonal antibody anti-FcγRIIal, IV-3 (2 [µ/ml), abolished SK-induced platelet aggregation and SK-enhanced ADP-induced platelet aggregation. In all cases (25 out of 25 subjects), RSTA failed to potentiate platelet response to ADP.These findings confirm that RSTA has a lesser fibrinogenolytic ability than SK and suggest its negligeable effect on platelet function.

scholarly journals Role of platelet membrane glycoprotein IIb-IIIa in agonist-induced tyrosine phosphorylation of platelet proteins.

1990 ◽  
Vol 111 (6) ◽  
pp. 3117-3127 ◽  
Author(s):  
A Golden ◽  
J S Brugge ◽  
S J Shattil
Keyword(s):  
Platelet Aggregation ◽  
Tyrosine Phosphorylation ◽  
Dense Granule ◽  
Platelet Response ◽  
Induce Platelet Aggregation ◽  
Fibrinogen Binding ◽  
Molecular Masses ◽  
Dense Granule Secretion ◽  
Granule Secretion ◽  
Platelet Proteins

Treatment of platelets with thrombin was shown previously to induce rapid changes in tyrosine phosphorylation of several platelet proteins. In this report, we demonstrate that a variety of agonists which induce platelet aggregation also stimulate tyrosine phosphorylation of three proteins with apparent molecular masses of 84, 95, and 97 kD. Since platelet aggregation requires the agonist-induced activation of an integrin receptor (GP IIb-IIIa) as well as the binding of fibrinogen to this receptor, we examined the relationship between tyrosine phosphorylation and the function of GP IIb-IIIa. When platelets were examined under conditions that either precluded the activation of GP IIb-IIIa (prior disruption of the complex by EGTA at 37 degrees C) or the binding of fibrinogen (addition of RGDS or an inhibitory mAb), tyrosine phosphorylation of the 84-, 95-, and 97-kD proteins was not observed. However, although both GP IIb-IIIa activation and fibrinogen binding were necessary for tyrosine phosphorylation, they were not sufficient since phosphorylation was observed only under conditions in which the activated platelets were stirred and allowed to aggregate. In contrast, tyrosine phosphorylation was not dependent on another major platelet response, dense granule secretion. Furthermore, granule secretion did not require tyrosine phosphorylation of this set of proteins. These experiments demonstrate that agonist-induced tyrosine phosphorylation is linked to the process of GP IIb-IIIa-mediated platelet aggregation. Thus, tyrosine phosphorylation may be required for events associated with platelet aggregation or for events that follow aggregation.

Conditions Influencing the Interaction of Asialo von Willebrand Factor with Human Platelets – The Effects of External Ionized Calcium Concentration and the Role of Arachidonate Pathway

1988 ◽  
Vol 60 (02) ◽  
pp. 280-288 ◽  
Author(s):  
Marco Cattaneo ◽  
J Fraser Mustard ◽  
Maria T Canciani ◽  
Mary Richardson ◽  
Augusto B Federici ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Calcium Concentration ◽  
Thromboxane A2 ◽  
Human Platelets ◽  
Ionized Calcium ◽  
Platelet Response ◽  
Induce Platelet Aggregation ◽  
Release Reaction ◽  
Von Willebrand ◽  
Primary Platelet

SummaryWe have studied the interaction of ASvWf with human platelets in PRP and in suspensions of washed platelets containing either physiological or low external ionized calcium concentration [Ca2+]0. In hirudin-PRP or in washed platelets in 1.5-2 mM CaCl2, ASvWf up to 50 μg/ml does not induce platelet aggregation or the release reaction. When [Ca2+]c is decreased by addition of citrate to hirudin-PRP or when no CaCl2 is added to washed platelet suspensions, ASvWf does induce platelet aggregation and the release reaction. In low [Ca2+]0, ASvWf interacts with platelet GPIb to cause primary aggregation of disc-shaped platelets to each other through GPIIb/IIIa, with or without added fibrinogen. This primary platelet aggregation leads to thromboxane A2 formation and secondary aggregation and the release reaction. With [Ca2+]0 in the physiological range, there is less ASvWf interaction with GPIb, no primary platelet aggregation and no thromboxane A2 formation. The ASvWf-platelet interaction at physiological [Ca2+]0, however, enhances the platelet response to collagen or epinephrine.

Abnormal Prothrombin Consumption (Pc) In Bernard Soulier-Syndrome (BSS)

1981 ◽  
Author(s):  
J Pizzuto ◽  
M P Reyna ◽  
A González-Angulo ◽  
M R Morales ◽  
S Dorantes
Keyword(s):  
Platelet Count ◽  
Platelet Aggregation ◽  
Aplastic Anemia ◽  
Normal Subjects ◽  
Procoagulant Activity ◽  
Normal Platelet ◽  
Abnormal Bleeding ◽  
Recalcification Time ◽  
Bernard Soulier Syndrome

The abnormal PC in BSS is a defect that has not been extensively studied to date. For this reason 4 patients with BSS who had normal platelet aggregation tests (except with bovine fibrinogen and with Ristocetin), but abnormal bleeding times and PC on different occasions, during which they showed variable thrombocytopenia, were studied. The PC was normal in only one case and in only one occasion, which was coincidental with a circulating platelet count that also approximated normal.The abnormal PC in the 4 cases was corrected when platelet substitute, or washed platelets from normal subjects or from patients with BSS were added. These same platelets also corrected the abnormal PC in cases of ITP or aplastic anemia, and shortened the recalcification time of platelet-poor plasmas from normal subjects and patients with specific plasma deficiencies (Factors V, VIII and XI).The above suggests that the abnormal PC in some cases of BSS may be due to the thrombocytopenia rather than to a defect in the procoagulant activity of the platelets in this syndrome.

Shear-Induced Platelet Aggregation in Normal Subjects and Stroke Patients

1995 ◽  
Vol 74 (05) ◽  
pp. 1329-1334 ◽  
Author(s):  
Konstantinos Konstantopoulos ◽  
James C Grotta ◽  
Cynthia Sills ◽  
Kenneth K Wu ◽  
J David Heliums
Keyword(s):  
Ischemic Stroke ◽  
Platelet Aggregation ◽  
Platelet Activation ◽  
Platelet Reactivity ◽  
Normal Subjects ◽  
Shear Stresses ◽  
Stroke Patients ◽  
Induce Platelet Aggregation ◽  
Partially Occluded

SummaryElevated levels of shear stress that occur in stenotic arteries may induce platelet aggregation and initiate thrombosis. Shear-induced platelet aggregation (SIPA) was studied in groups of ischemic stroke patients and normal subjects using a viscometric-flow cytometric technique. Twenty-three patients who sustained an ischemic stroke that was not of cardiac origin were included in this study, and were classified either as atherosclerotic (n = 15) or as lacunar (n = 8) stroke patients. The results show that shear stresses at the levels which occur in arteries partially occluded by atherosclerosis or vascular spasm strongly activate and aggregate platelets, and this response is much more pronounced in non-lacunar stroke patients who had documented atherosclerotic disease of their cerebral vessels. SIPA is not affected by the time of blood drawing after the onset of stroke suggesting that these platelet abnormalities are not transient but chronic. Furthermore, the extent of platelet activation detected by an anti-P-selectin monoclonal antibody and the proportion of neutrophil-platelet aggregates circulating in vivo are significantly higher in the atherosclerotic stroke patients studied at least one month after the onset of stroke. The results indicate that the enhanced platelet responses observed in atherosclerotic stroke patients are not consequences of ischemia, and therefore both platelet activation and elevated SIPA may be considered as important risk factors for stroke. The methodology developed in this work may be useful for characterization of platelet reactivity, and may contribute to our understanding of thrombotic mechanisms.

Effect of Temperature on ADP-Induced Platelet Aggregation

1973 ◽  
Vol 29 (01) ◽  
pp. 183-189
Author(s):  
C. A Praga ◽  
E. M Pogliani
Keyword(s):  
Platelet Aggregation ◽  
Incubation Period ◽  
Room Temperature ◽  
Important Variable ◽  
Practical Significance ◽  
Effect Of Temperature ◽  
Induce Platelet Aggregation ◽  
Cuvette Holder ◽  
Exact Temperature

SummaryTemperature represents a very important variable in ADP-induced platelet aggregation.When low doses of ADP ( < 1 (μM) are used to induce platelet aggregation, the length of the incubation period of PRP in the cuvette holder of the aggregometer, thermostatted at 37° C, is very critical. Samples of the same PRP previously kept at room temperature, were incubated for increasing periods of time in the cuvette of the aggregometer before adding ADP, and a significant decrease of aggregation, proportional to the length of incubation, was observed. Stirring of the PRP during the incubation period made these changes more evident.To measure the exact temperature of the PRP during incubation in the aggre- gometer, a thermocouple device was used. While the temperature of the cuvette holder was stable at 37° C, the PRP temperature itself increased exponentially, taking about ten minutes from the beginning of the incubation to reach the value of 37° C. The above results have a practical significance in the reproducibility of the platelet aggregation test in vitro and acquire particular value when the effect of inhibitors of ADP induced platelet aggregation is studied.Experiments carried out with three anti-aggregating agents (acetyl salicyclic acid, dipyridamole and metergoline) have shown that the incubation conditions which influence both the effect of the drugs on platelets and the ADP breakdown in plasma must be strictly controlled.

Glycoprotein Ib Has a Partial Role in Platelet-von Willebrand Factor Collagen Interaction

1988 ◽  
Vol 60 (02) ◽  
pp. 182-187 ◽  
Author(s):  
Morio Aihara ◽  
Ken Tamura ◽  
Ryuko Kawarada ◽  
Keizou Okawa ◽  
Yutaka Yoshida
Keyword(s):  
Platelet Aggregation ◽  
Von Willebrand Factor ◽  
Ricinus Communis ◽  
Protein S ◽  
Platelet Membrane ◽  
Membrane Glycoprotein ◽  
Normal Plasma ◽  
Ricinus Communis Agglutinin ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryThe adhesion of human fixed washed platelets (FWP) to collagen was decreased after treatment with Serratia marcescens protease (SP), which removed 95% of the glycocalicin from platelet membrane glycoprotein (GP) lb. However, the diminished adhesion of SP treated FWP to collagen could still be increased in the presence of purified von Willebrand factor (vWF). This ability of vWF to increase FWP adhesion to collagen is defined as collagen cofactor (CCo). The adhesion of FWP to collagen was not affected by a monoclonal antibody (MAb) to GP Ilb/IIIa (10E5), that inhibits ADP and collagen induced platelet aggregation. On the other hand, it was decreased by 50% by a MAb to GP lb (6D1), that inhibits ristocetin induced platelet aggregation. Adhesion of FWP in buffer to collagen was completely inhibited by Ricinus communis agglutinin I or concanavalin A, while Lens culinalis agglutinin and wheat germ agglutinin showed 50% inhibition. The FWP adhesion to collagen in the presence of vWF (normal plasma) was unaffected by MAbs to GP Ilb/IIIa (10E5, P2, HPL1) but was decreased to 32-38% by MAbs to GP lb (6D1, AN51, HPL11). A MAb to vWF (CLB-RAg 35), that inhibits ristocetin induced binding of vWF to platelets, decreased the CCo of normal plasma by 70%. The MAb, CLB-RAg 201, that inhibits the binding of vWF to collagen, completely inhibited the CCo of normal plasma. In conclusion, our data suggest that (1) GP lb has a partial role in FWP adhesion to collagen; (2) the binding of vWF to collagen is required for the expression of CCo; (3) CCo is partly mediated through GP lb; but (4) other platelet membrane protein(s) besides GP lb or GP Ilb/IIIa must also be involved in FWP-vWF-collagen interactions.

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