scholarly journals Morphologic Platelet Changes in Vitro and During Thrombus Formation in the Rat

1977 ◽  
Author(s):  
R. Wiedemann ◽  
K. Breddin ◽  
H. Grun ◽  
W. Weichert
Keyword(s):  
Incubation Temperature ◽  
Thrombus Formation ◽  
Shape Change ◽  
Vascular Lesions ◽  
Platelet Adhesiveness ◽  
Platelet Morphology ◽  
Mesenteric Vessels ◽  
Adhesion Of Platelets ◽  
Spherical Transformation

Using high power Nomarski optics the shape change of thrombocytes can be shown. Platelets appear in their native shape as flat discs, less than 25% show pseudopodes. Depending on the time after blood sampling and on incubation temperature platelets in PRP or citrated blood swell and form tentacles. The addition of ADP to PRP induces the formation of aggregates. Single platelets form large vesicles rupturing and releasing granulated material. The remaining platelet material fuses. Bencyclan affects platelet morphology by inducing a spherical transformation, which is paralleled by the inhibition of platelet adhesiveness, spreading and aggregation. Observations in small mesenteric vessels of the rat show platelets in their native shape under stasis conditions. Vascular lesions are produced with a focused laserbeam (Hadron 513 biolaser). Immediately after the lesion platelets stick to the site of the microburn. Within seconds these platelets swell and form protrusions. After 3 - 10 min the vessel is occluded by a thrombus, of platelets, which undergo further swelling. Later the thrombus is partially or completely swept away and the vessel is recanalized. Irreversible fusion of platelets is rarely observed. These morphologic platelet changes differ markedly from those observed during in vitro aggregation. Injection of a new antithrombotic substance (Bay G 6575) diminishes the adhesion of platelets on the vessel lesion. The morphologic changes of single platelets (primary shape change) probably represent basic processes in hemostasis and thrombus formation.

scholarly journals Morphologic Platelet Changes in Citrate Blood and PRP

1977 ◽  
Author(s):  
R. Wiedemann ◽  
K. Breddin ◽  
H. Grun
Keyword(s):  
High Power ◽  
Room Temperature ◽  
Incubation Temperature ◽  
Thrombus Formation ◽  
Shape Change ◽  
Platelet Adhesiveness ◽  
Platelet Morphology ◽  
Spherical Transformation ◽  
Citrate Blood

Using high power Nomarski optics the film presents the shape change of thrombocytes in vitro. Their native shape can be studied by immediate fixation of blood at venepuncture. Platelets appear as flat discs. Less than 25% show pseudopodes. In citrate blood and PRP a pro-qressing shape change occurs depending on time after blood sampling and on incubation temperature. Platelets tend to swell and tentacle formation continues with time. At room temperature 90% of thrombocytes have undergone these changes within 60 min. The addition of ADP (10-6 molar) to PRP induces the formation and rupture of large vesicles in single platelets. Thrombocytes are aggregating, many of the aggregated platelets show the same large vesicles. They are bursting and the release of a granular material can be observed. The remaining platelet material is fusing to an unstructured mass. Bencyclan (2 × 10-4 molar) affects platelet morphology by inducing a spherical transformation, which is paralleled by the inhibition of platelet adhesiveness, spreading and aggregation. Finally a platelet is shown spreading on a glass surface. The mor-nhologic changes of single platelets (primary shape change) demonstrated in the film probably represent basic processes in hemostasis and thrombus formation.

scholarly journals Morphologic Platelet Changes During Thrombus Formation in the Rat

1977 ◽  
Author(s):  
R. Wiedemann ◽  
W. Weichert ◽  
K. Breddin
Keyword(s):  
Vessel Wall ◽  
Thrombus Formation ◽  
Vascular Lesions ◽  
Mesenteric Vessels ◽  
Platelet Thrombus ◽  
Adhesion Of Platelets ◽  
Damaged Vessel ◽  
Morphologic Changes

The film presents observations in small mesenteric vessels (diameter 10-20 μm) of the rat using high power Nomarski optics. Under stasis conditions platelets appear as flat discs. Leucocytes are often seen creeping slowly along the intact vessel wall. Vascular lesions are produced with a focused laser beam (Hadron 513 biolaser). Immediately after the lesion platelets stick to the site of the microburn either in their native disc like shape without apparent morphologic changes or with protrusions. Within seconds these platelets swell and form protrusions. After 3-10 min, depending on the size of the lesion the vessel is occluded by a platelet thrombus. Platelets undergo further swelling. Later the thrombus is partially or completely swept away and the vessel is recanal i zed. Irreversible fusion of platelets is rarely observed. . New, usually smaller thrombi form at the damaged vessel wall. The morphologic platelet changes observed differ markedly from the changes observed during aggregation in vitro. After injection of a new antithrombotic substance (Bay G 7565) the adhesion of platelets to the damaged area is remarkably diminished. The few platelets which adhere to the site of injury show the same swelling and transformation like in untreated animals. The film demonstrates that it is possible to investigate morphologic changes of single platelets during thrombus formation. It seems possible to adapt this model for the in vivo study of antithrombotic drugs.

scholarly journals Type of Agitation and Platelet Viability and Function After 22°C Storage: Correlation with Maintenance of Discoid Shape

1977 ◽  
Author(s):  
S. Holme ◽  
K. Vaidja ◽  
S. Murphy
Keyword(s):  
Platelet Count ◽  
Shape Change ◽  
Storage Conditions ◽  
C Storage ◽  
Platelet Morphology ◽  
Citrate Dextrose ◽  
And Function ◽  
Change Response

Platelet viability as measured by in vivo 51cr recovery, platelet morphology, and in vitro aggregation with ADP and thrombin were studied with platelet concentrates (PC) stored for transfusion under carefully controlled conditions. The PC were prepared from whole blood with citrate-dextrose-phosphate as anticoagulant. The platelet count was kept between 0.8 − 1.6 × 106 platelets per mm3 in a volume of 50 ml. The PC were stored in containers constructed of polyethylene (PE) or Polyvinylchloride (PVC) at 22°C for 72 hours. The bags were placed on a horizontal shaker or a ferris wheel type of apparatus during storage. No significant changes in pH or platelet count were observed during storage. PC stored on the wheel showed a moderate loss of viability and marked loss of aggregation response compared to PC on the shaker. Under optimal conditions with PC in PE on the shaker maximal rate of aggregation was reduced only 26% compared to fresh PC. PC stored in PVC showed a statistically significant greater decrease. A good correlation was observed between the percentage of discoid platelets present in the PC as judged by phase microscopy and the extent of platelet shape change response to ADP. Both parameters correlated positively with in vivo 51Cr recovery. We conclude: 1) The type of agitation used significantly effects maintenance of platelet viability and function during storage. 2) Under the conditions used, in vitro function was better preserved in PE than in PVC bags. 3) In vitro function is not inevitably lost during storage at 22°C, but is critically dependent on storage conditions. 4) In vivo platelet viability (51Cr recovery) correlates with maintenance of disc shape. The latter can be quantitated by the shape change response with ADP.

STUDIES ON ELECTRICALLY INDUCED THROMBOSIS AND RELATED PHENOMENA

1966 ◽  
Vol 44 (6) ◽  
pp. 881-886 ◽  
Author(s):  
C. R. Cowan ◽  
Frank C. Monkhouse
Keyword(s):  
Thrombus Formation ◽  
Electrical Current ◽  
Platinum Electrodes ◽  
Metal Electrodes ◽  
Ph Changes ◽  
Gas Formation ◽  
Negative Pole ◽  
Mesenteric Vessels ◽  
Saline Solutions

Microampere currents applied with metal electrodes to the mesenteric vessels of mice caused thrombosis, accompanied by electrolyte dissociation and gas formation. When the products of dissociation were removed, clumping, constriction, or thrombosis did not occur. When glass–starch electrodes were used, currents up to 200 μA, applied for 30 minutes, were without effect. Changing to platinum electrodes and applying 50-μA currents caused, in less than 30 seconds, constriction at the negative pole, clumping, and thrombosis, without constriction at the positive pole. Measurements showed an increase in pH at the negative pole and a decrease at the positive pole. When saline solutions with increased or decreased pH were applied to the vessels, constriction and thrombus formation occurred similar to those produced by electrical current. Experiments were done on heparinized blood in vitro with a U-tube designed to contain the products of electrolysis at each pole. With platinum electrodes a coagulum formed at the positive pole and pH changes occurred at both poles. With glass–starch electrodes these changes did not occur.

scholarly journals Platelet storage at 22 degrees C: effect of type of agitation on morphology, viability, and function in vitro

Blood ◽  
1978 ◽  
Vol 52 (2) ◽  
pp. 425-435 ◽  
Author(s):  
S Holme ◽  
K Vaidja ◽  
S Murphy
Keyword(s):  
Platelet Count ◽  
Shape Change ◽  
Normal Platelet ◽  
Platelet Storage ◽  
Platelet Morphology ◽  
And Function ◽  
Change Response ◽  
Citrate Phosphate

Abstract Recovery in vivo after 51Cr labeling, platelet morphology, and platelet aggregation were studied with platelet concentrates (PC) stored for transfusion under carefully controlled conditions. PC were prepared to a final volume of 50 ml from whole blood anticoagulated with citrate- phosphate-dextrose (CPD). The platelet count was kept between 0.8 and 1.6 X 10(12) platelets/liter. The PC were stored in bags constructed of polyvinylchloride (PVC) or polyethylene (PE) at 22 degrees C for 72 hr. The bags were placed on a horizontal shaker or a ferris wheel for agitation during storage. No significant changes in pH or platelet count were observed during storage. PC stored on the wheel showed moderate loss of viability and a marked deterioration of platelet morphology and aggregation compared to the shaker. PC stored on the shaker in bags made of PE showed better aggregation with ADP and thrombin but had the same viability and morphology as PC in bags constructed of PVC. Maintenance of normal platelet morphology as determined by phase-contrast microscopy, extent of shape change response, and the size distribution according to the Coulter Counter correlated with recovery in vivo.

scholarly journals Platelet storage at 22 degrees C: effect of type of agitation on morphology, viability, and function in vitro

Blood ◽  
1978 ◽  
Vol 52 (2) ◽  
pp. 425-435 ◽  
Author(s):  
S Holme ◽  
K Vaidja ◽  
S Murphy
Keyword(s):  
Platelet Count ◽  
Shape Change ◽  
Normal Platelet ◽  
Platelet Storage ◽  
Platelet Morphology ◽  
And Function ◽  
Change Response ◽  
Citrate Phosphate

Recovery in vivo after 51Cr labeling, platelet morphology, and platelet aggregation were studied with platelet concentrates (PC) stored for transfusion under carefully controlled conditions. PC were prepared to a final volume of 50 ml from whole blood anticoagulated with citrate- phosphate-dextrose (CPD). The platelet count was kept between 0.8 and 1.6 X 10(12) platelets/liter. The PC were stored in bags constructed of polyvinylchloride (PVC) or polyethylene (PE) at 22 degrees C for 72 hr. The bags were placed on a horizontal shaker or a ferris wheel for agitation during storage. No significant changes in pH or platelet count were observed during storage. PC stored on the wheel showed moderate loss of viability and a marked deterioration of platelet morphology and aggregation compared to the shaker. PC stored on the shaker in bags made of PE showed better aggregation with ADP and thrombin but had the same viability and morphology as PC in bags constructed of PVC. Maintenance of normal platelet morphology as determined by phase-contrast microscopy, extent of shape change response, and the size distribution according to the Coulter Counter correlated with recovery in vivo.

Thrombus formation on artificial surfaces: Correlative microscopy

1990 ◽  
Vol 48 (3) ◽  
pp. 840-841
Author(s):  
Quintin J. Lai ◽  
Stuart L. Cooper ◽  
Ralph M. Albrecht
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Low Voltage ◽  
Thrombus Formation ◽  
Blood Platelets ◽  
Polymer Surfaces ◽  
Flow Conditions ◽  
Transmission Electron ◽  
Adhesion Of Platelets ◽  
Microscopic Techniques

Thrombus formation and embolization are significant problems for blood-contacting biomedical devices. Two major components of thrombi are blood platelets and the plasma protein, fibrinogen. Previous studies have examined interactions of platelets with polymer surfaces, fibrinogen with platelets, and platelets in suspension with spreading platelets attached to surfaces. Correlative microscopic techniques permit light microscopic observations of labeled living platelets, under static or flow conditions, followed by the observation of identical platelets by electron microscopy. Videoenhanced, differential interference contrast (DIC) light microscopy permits high-resolution, real-time imaging of live platelets and their interactions with surfaces. Interference reflection microscopy (IRM) provides information on the focal adhesion of platelets on surfaces. High voltage, transmission electron microscopy (HVEM) allows observation of platelet cytoskeletal structure of whole mount preparations. Low-voltage, high resolution, scanning electron microscopy allows observation of fine surface detail of platelets. Colloidal gold-labeled fibrinogen, used to identify the Gp Ilb/IIIa membrane receptor for fibrinogen, can be detected in all the above microscopies.

Physico-Chemical Explanation of Blood Cell Adhesion in Thrombus Formation

1976 ◽  
Vol 36 (02) ◽  
pp. 430-440 ◽  
Author(s):  
A Marmur ◽  
E Ruckenstein ◽  
S. R Rakower
Keyword(s):  
Blood Cells ◽  
Thrombus Formation ◽  
Experimental Information ◽  
Deposition Surface ◽  
Physico Chemical ◽  
Quantitative Results ◽  
Energy Of Interaction ◽  
Induced Aggregation ◽  
Adhesion Of Platelets ◽  
Hydrodynamic Factors

SummaryA model is suggested which assumes that the rate of deposition of cells is determined both by hydrodynamic factors and by Brownian motion over the potential barrier caused by London and double-layer forces in the immediate vicinity of the deposition surface. The height of the barrier in the potential energy of interaction between blood cells and various surfaces is analyzed in relation to the physical properties of the cells, surfaces, and solutions. Based on this analysis, the adhesion of platelets to injured blood vessel walls and to non-biologic materials, the lack of adhesion of red blood cells under the same conditions, the mechanism of ADP induced aggregation and the interaction with blood flow are explained. The qualitative predictions of the model are substantiated by available experimental information. Quantitative results are presented in terms of a time constant, which typifies a period of contact with a surface, during which appreciable deposition occurs.

Experimental Studies on a Recombinant Hirudin, CGP 39393

1991 ◽  
Vol 65 (04) ◽  
pp. 355-359 ◽  
Author(s):  
E Gray ◽  
J Watton ◽  
S Cesmeli ◽  
T W Barrowcliffe ◽  
D P Thomas
Keyword(s):  
Thrombin Generation ◽  
Bleeding Time ◽  
Thrombus Formation ◽  
Experimental Studies ◽  
Venous Stasis ◽  
Antithrombotic Agent ◽  
Recombinant Hirudin ◽  
Excessive Bleeding ◽  
Generation Test

SummaryThe in vitro anticoagulant activities of recombinant desulphatohirudin (r-hirudin) were studied in the activated partial thromboplastin time (APTT) and the thrombin generation test : systems. In the APTT at concentrations below 5 μg/ml, r-hirudin showed a dose-response curye. At concentrations above 5 μg/ml, the plasma became unclottable, but in the thrombin generation test , at least 10 μg/ml of r-hirudin was required for full inhibition of thrombin generation. The antithrombotic effect was assessed using a rabbit venous stasis model; 150 μg/ml r-hirudin completely prevented thrombus formation at 10 and 20 min stasis. At antithrombotic dose, the mean bleeding time ratio measured in a rabbit ear template model, was not prolonged over control values. At higher doses, the bleeding time ratios were higher than those observed for the same dosage of heparin. These data indicate that while r-hirudin is an effective antithrombotic agent, antithrombotic doses have to be carefully titrated to avoid excessive bleeding.

In Vitro Assay of Platelet Adhesiveness with Washed and Tanned Human Red Cells

1968 ◽  
Vol 20 (03/04) ◽  
pp. 384-396 ◽  
Author(s):  
G Zbinden ◽  
S Tomlin
Keyword(s):  
Platelet Adhesion ◽  
Sodium Citrate ◽  
Blood Platelets ◽  
In Vitro Assay ◽  
Red Cells ◽  
Platelet Adhesiveness ◽  
Vitro Assay ◽  
In Vitro System ◽  
Human Red Cells

SummaryAn in vitro system is described in which adhesion of blood platelets to washed and tannic acid-treated red cells was assayed quantitatively by microscopic observation. ADP, epinephrine and TAME produced a reversible increase in platelet adhesiveness which was antagonized by AMP. With Evans blue, polyanetholsulfonate, phthalanilide NSC 38280, thrombin and heparin at concentrations above 1-4 u/ml the increase was irreversible. The ADP-induced increase in adhesiveness was inhibited by sodium citrate, EDTA, AMP, ATP and N-ethylmaleimide. EDTA, AMP and the SH-blocker N-ethylmaleimide also reduced spontaneous platelet adhesion to red cells. No significant effects were observed with adenosine, phenprocoumon, 5-HT, phthalanilide NSC 57155, various estrogens, progestogens and fatty acids, acetylsalicylic acid and similarly acting agents, hydroxylamine, glucose and KCN. The method may be useful for the screening of thrombogenic and antithrombotic properties of drugs.

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