Altered Platelet Shape Change in Hereditary Gelsolin Asp187Asn-related Amyloidosis

2000 ◽  
Vol 83 (03) ◽  
pp. 491-495 ◽  
Author(s):  
Kaija Javela ◽  
Hannu Somer ◽  
Riitta Kekomäki ◽  
Sari Kiuru
Keyword(s):  
Factor Viii ◽  
Light Transmission ◽  
Platelet Rich Plasma ◽  
Shape Change ◽  
Coagulation Factor ◽  
Coagulation Factor Viii ◽  
Bleeding Tendency ◽  
Knock Out ◽  
Ristocetin Cofactor ◽  
Platelet Shape

SummaryHereditary gelsolin-related amyloidosis (AGel amyloidosis) is a systemic disorder caused by a G654A or G654T mutation in the gene coding for gelsolin, an actin-modulating protein. Altered platelet shape change has been demonstrated in gelsolin-deficient knock-out mice, but this has not been studied in humans with gelsolin deficiency. We measured platelet shape change, characterized by maximal decrease in light transmission (D) and reaction time (T), and aggregation, associated with stimulation of platelets with different agonists in platelet rich plasma, as well as coagulation factor VIII and ristocetin cofactor activities in 20 patients, 10 healthy sibs and 20 healthy control subjects. Statistically significant alterations of parameters describing platelet shape change (D, T) were observed after stimulation with adenosine diphosphate and collagen in patients when compared to healthy subjects, but not in maximal aggregation responses, platelet counts, coagulation factor VIII or ristocetin cofactor activity levels. Patients had more haemostatic derangements. Our results suggest that, in addition to amyloid deposition, the G654A gelsolin gene defect causes altered gelsolin-mediated cellular mechanisms, which may contribute, e. g., to bleeding tendency in AGel amyloidosis patients.

scholarly journals Kinetics of ADP-induced human platelet shape change: apparent positive cooperativity

1980 ◽  
Vol 58 (1) ◽  
pp. 45-52 ◽  
Author(s):  
John G. Milton ◽  
W. Yung ◽  
C. Glushak ◽  
M. M. Frojmovic
Keyword(s):  
Light Transmission ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Shape Change ◽  
Hill Coefficient ◽  
A Value ◽  
The Hill ◽  
Kinetics Of ◽  
Type Response ◽  
Platelet Shape

The kinetics of ADP-induced human platelet shape change have been examined. Initial velocities of platelet shape change were estimated by two methods: (1) the slope of the initial decrease in light transmission through stirred, citrated platelet-rich plasma, and (2) direct examination of platelet morphologies by phase-contrast microscopy. In both cases, a value of the Hill coefficient, NH, significantly greater than 1 is obtained (2.0 ± 0.2 and 1.8 ± 0.2, respectively). The observed elevated value of NH is not due to a substantial fraction of the ADP being platelet bound, the presence of factors in the plasma, platelet heterogeneity, or the influence of the rate of platelet shape change reversion. Our observations suggest that ADP-induced platelet shape change may be a positively cooperative or "threshold" type response.

48740 RP INHIBITS PLATELET SHAPE CHANGE INDUCED BY PAF-ACETHER IN VITRO.

1987 ◽  
Author(s):  
G Jung ◽  
P Sedivy
Keyword(s):  
Sodium Citrate ◽  
Light Transmission ◽  
Platelet Rich Plasma ◽  
Shape Change ◽  
Maximum Amplitude ◽  
Maximal Velocity ◽  
Maximal Amplitude ◽  
Plasma Properties ◽  
Platelet Shape

Platelet shape change (PSC) is the first measurable physiological response to platelet pro-aggregant agonists such as PAF-acether (PAF) (1). The laser thromborheometer (2) was used to assess the PSC (detected as decrease in light scattering as 2 of maximal velocity) and the platelet aggrega tion (detected as increase in the light transmission as 2 of maximal velocity and maximal amplitude) in citrated platelet -rich plasma (cPRP) (1 volume 3.8 2 sodium citrate ± 9 volumes blood) from 12 volunteers of either sex. PAF concentrations ranging from 0.1 to 1 yM induced PSC (range of velocities : 13.2-69.8 2 of maximal velocity, n = 12) and platelet aggregation (range of velocities : 9.3-22.2 2 of maximal velocity and maximum amplitude of aggregation always superior to 20 2, n = 12). These effects were inhibited by 48740 R.P., 3-(3- pyridy1)-1H,3H pyrrolo [1 , 2-c] thiazo1e-7-carboxamide (100200 yM) a selective and competitive PAF-antagonist (3). For instance, 100 yM 48740 RP decreased by 76.4 ± 3.5 (mean ± S.E.M., n = 3) PSC evoked by 0.1 yM of PAF. Furthermore, 48740 RP was also able to reduce PSC in heparinized platelet - r ich plasma (hPRP). The antagonist effects of 46740 RP could be overcome by increasing PAF concentrations in the cPRP and hPRP. During this study, 6 volunteers were found, in whom even concentrations of PAF up to 10.5 pM failed to induce an amplitude of aggregation in cPRP greater than 20 2 whereas PSC was in the range of 19.1-79.4 2 of maximal velocity. These responses to PAF which were antagonized by 48740 RP were not due to an alteration in plasma properties ; thus, they are proposed to result from undetermined changes occuring at the level of the platelet (e.g.) decreased number of PAF-operationa1 receptors or alteration of the excitation - response pathways). In conclusion, 48740 RP is an antagonist of PAF-evoked aggregation and PSC in cPRP from volunteers responding either normally or poorly to PAF. (1) LAPETINA E.G. et al. J. Biol. Chem. 258, 7241 (1983). (2) JUNG G. et al. Nouv. Rev. Fr. H6matol. 27, 103 (1985). (3) SEDIVY P. et al. Thromb. Haemost. 54, 185 (1985).

scholarly journals Importance of Human Platelet Echinocytes for Procoagulant Activity

1977 ◽  
Author(s):  
E. Toth ◽  
M.M. Frojmovic
Keyword(s):  
Light Transmission ◽  
Platelet Rich Plasma ◽  
Shape Change ◽  
Adenosine Diphosphate ◽  
Procoagulant Activity ◽  
Rate Limiting Step ◽  
Rate Limiting ◽  
Recalcification Time ◽  
Free Plasma ◽  
Platelet Shape

Various agents can be used to transform platelets from the disc-form (discocytes) into spherical shapes from which many pseudopodia project (echinocytes). This shape change normally precedes platelet aggregation and release. The relative importance of these changes for platelet procoagulant activity was investigated. Recalcification times of platelet-rich plasma were used to monitor procoagulant activity, and echinocytes were maintained by the addition of either thrombin, serotonin, adenosine diphosphate (ADP) or water. The amounts of these agents added were insufficient to cause aggregation and release, and had no effect on the recalcification times of platelet-free plasma. Platelet shape and extent of aggregation were assessed from the stirring dependent changes in light transmission in an aggregometer, and by direct observation under a phase contrast microscope. When more than 60% of the platelets were echinocytes, recalcificat ion times were shortened by at least 50%. Aggregates preformed with serotonin and ADP did not further shorten the reca1cifi cat ion times. The importance of the echinocyte for procoagulant activity is further supported by the observations that:1)aggregates of discocytes formed with adrenaline caused only 20% shortening of recalcification times,2)both echinocytes (for discocyte preparations) and their aggregates appeared only during the last 10% of the total recalcification time, and3) inhibition of the ADP-induced discocyte-echinocyte transformation by AMP prolonged recalcification times by 300%. These results suggest that platelet discocyte-echinocyte transformation is an important rate limiting step for platelet procoagulant activity in blood clotting.

Adenosine Diphosphate (ADP)-Induced ⍺-Granules Release from Platelets of Native Whole Blood Is Reduced by Ticlopidine but Not by Aspirin or Dipyridamole

1986 ◽  
Vol 56 (02) ◽  
pp. 147-150 ◽  
Author(s):  
V Pengo ◽  
M Boschello ◽  
A Marzari ◽  
M Baca ◽  
L Schivazappa ◽  
...  
Keyword(s):  
Whole Blood ◽  
Light Transmission ◽  
Ex Vivo ◽  
Early Stage ◽  
Shape Change ◽  
Adenosine Diphosphate ◽  
Dose Dependent ◽  
Plateletderived Growth Factor ◽  
Platelet Shape

SummaryA brief contact between native whole blood and ADP promotes a dose-dependent release of platelet a-granules without a fall in the platelet number. We assessed the “ex vivo” effect of three widely used antiplatelet drugs, aspirin dipyridamole and ticlopidine, on this system. Aspirin (a single 800 mg dose) and dipyridamole (300 mg/die for four days) had no effect, while ticlopidine (500 mg/die for four days) significantly reduced the a-granules release for an ADP stimulation of 0.4 (p <0.02), 1.2 (p <0.01) and 2 pM (p <0.01). No drug, however, completeley inhibits this early stage of platelet activation. The platelet release of α-granules may be related to platelet shape change of the light transmission aggregometer and may be important “in vivo” by enhancing platelet adhesiveness and by liberating the plateletderived growth factor.

scholarly journals Inhibition of human coagulation factor VIII by monoclonal antibodies. Mapping of functional epitopes with the use of recombinant factor VIII fragments

1989 ◽  
Vol 263 (1) ◽  
pp. 187-194 ◽  
Author(s):  
A Leyte ◽  
K Mertens ◽  
B Distel ◽  
R F Evers ◽  
M J M De Keyzer-Nellen ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Factor Viii ◽  
Factor Xa ◽  
Coagulation Factor ◽  
Procoagulant Activity ◽  
Coagulation Factor Viii ◽  
Coagulation Cascade ◽  
Restriction Enzyme Digestion ◽  
Proteolytic Activation

The epitopes of four monoclonal antibodies against coagulation Factor VIII were mapped with the use of recombinant DNA techniques. Full-length Factor VIII cDNA and parts thereof were inserted into the vector pSP64, permitting transcription in vitro with the use of a promoter specific for SP6 RNA polymerase. Factor VIII DNA inserts were truncated from their 3′-ends by selective restriction-enzyme digestion and used as templates for ‘run-off’ mRNA synthesis. Translation in vitro with rabbit reticulocyte lysate provided defined radiolabelled Factor VIII fragments for immunoprecipitation studies. Two antibodies are shown to be directed against epitopes on the 90 kDa chain of Factor VIII, between residues 712 and 741. The 80 kDa chain appeared to contain the epitopes of the other two antibodies, within the sequences 1649-1778 and 1779-1840 respectively. The effect of antibody binding to these sequences was evaluated at two distinct levels within the coagulation cascade. Both Factor VIII procoagulant activity and Factor VIII cofactor function in Factor Xa generation were neutralized upon binding to the region 1779-1840. The antibodies recognizing the region 713-740 or 1649-1778, though interfering with Factor VIII procoagulant activity, did not inhibit in Factor Xa generation. These findings demonstrate that antibodies that virtually inhibit Factor VIII in coagulation in vitro are not necessarily directed against epitopes involved in Factor VIII cofactor function. Inhibition of procoagulant activity rather than of cofactor function itself may be explained by interference in proteolytic activation of Factor VIII. This hypothesis is in agreement with the localization of the epitopes in the proximity of thrombin-cleavage or Factor Xa-cleavage sites.

scholarly journals Characterization and visualization of murine coagulation factor VIII-producing cells in vivo

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Morisada Hayakawa ◽  
Asuka Sakata ◽  
Hiroko Hayakawa ◽  
Hikari Matsumoto ◽  
Takafumi Hiramoto ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Factor Viii ◽  
Fluorescent Protein ◽  
Coagulation Factor ◽  
Coagulation Factors ◽  
Genetically Engineered ◽  
Coagulation Factor Viii ◽  
Liver Sinusoidal Endothelial Cells ◽  
Genetically Engineered Mice

AbstractCoagulation factors are produced from hepatocytes, whereas production of coagulation factor VIII (FVIII) from primary tissues and cell species is still controversial. Here, we tried to characterize primary FVIII-producing organ and cell species using genetically engineered mice, in which enhanced green fluorescent protein (EGFP) was expressed instead of the F8 gene. EGFP-positive FVIII-producing cells existed only in thin sinusoidal layer of the liver and characterized as CD31high, CD146high, and lymphatic vascular endothelial hyaluronan receptor 1 (Lyve1)+. EGFP-positive cells can be clearly distinguished from lymphatic endothelial cells in the expression profile of the podoplanin− and C-type lectin-like receptor-2 (CLEC-2)+. In embryogenesis, EGFP-positive cells began to emerge at E14.5 and subsequently increased according to liver maturation. Furthermore, plasma FVIII could be abolished by crossing F8 conditional deficient mice with Lyve1-Cre mice. In conclusion, in mice, FVIII is only produced from endothelial cells exhibiting CD31high, CD146high, Lyve1+, CLEC-2+, and podoplanin− in liver sinusoidal endothelial cells.

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