Changes In Platelet Adhesiveness Research Articles

Contributing Role of Mitochondrial Energy Metabolism on Platelet Adhesion, Activation and Thrombus Formation under Blood Flow Conditions

Platelets have an active energy metabolism mediated by mitochondria. However, the role of mitochondria in platelet adhesion, activation, and thrombus formation under blood flow conditions remains to be elucidated. Blood specimens were obtained from healthy adult volunteers. The consumption of glucose molecules by platelets was measured after 24 hours. Platelet adhesion, activation, and thrombus formation on collagen fibrils and immobilized von Willebrand factor (VWF) at a wall shear rate of 1,500 s−1 were detected by fluorescence microscopy with an ultrafast laser confocal unit in the presence or absence of mitochondrial functional inhibitors of carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP), antimycin A, and oligomycin. Consumption of glucose molecules within the first 24 h of 4.21 × 10−15 ± 4.46 x 10−15 (n = 6) increased to 13.82 × 10−15 ± 3.46 x 10−15 (n = 4) in the presence of FCCP, 12.11 × 10−15 ± 2.33 x 10−15 (n = 4) in the presence of antimycin A, and 11.87 × 10−15 ± 3.56 x 10−15 (n = 4) in the presence of oligomycin (p < .05). These mitochondrial functional blockers did not influence both surface area coverage by platelets and the 3-dimensional size of platelet thrombi formed on the collagen fibrils. However, a rapid increase in the intracellular calcium ion concentration ([Ca2+] i ) upon adhering on immobilized VWF decreased significantly from 405.5 ± 86.2 nM in control to 198.0 ± 79.2 nM in the presence of FCCP (p < .005). A similar decrease in the rapid increase in ([Ca2+] i ) was observed in the presence of antimycin A and oligomycin. Mitochondrial function is necessary for platelet activation represented by a rapid increase in [Ca2+] i after platelet adhesion on VWF. However, the influence could not be detected as changes in platelet adhesion or 3-dimensional growth of platelet thrombi on collagen fibrils.

Effects of Biomaterial Chemical Heterogeneity on Fibrinogen Activity-Platelet Adhesion Relationships

Fibrinogen adsorbed on material surfaces undergoes conformational changes that expose the platelet binding epitope located in the gamma-chain dodecapeptide. Circulating blood platelets bind to this exposed region, leading to platelet adhesion and activation, eventually forming a surface-induced thrombus. We have developed an AFM technique utilizing an antibody-modified probe that allows us to calculate the probability of this epitope being available following fibrinogen adsorption to solid surfaces, and have shown that the time-dependent changes in this probability of antibody binding correlate with temporal changes in platelet adhesion to materials. Recently, we have begun to explore how well this probability of adhesion correlates to platelet adhesion across a variety of different polymeric biomaterials. Results demonstrate that there is a strong relationship between this probability and measured platelet adhesion for 3 different homopolymer materials (figure 1), but two different phase-separated polyurethane (PU) materials possessing heterogeneous surface chemistries appear to deviate from this probability/adhesion relationship. These results suggest that the ∼50 to 100 nm sized phases in PU materials may affect the ability of platelets to bind to fibrinogen in a manner that leads to the improved blood compatibility seen with PU materials.View Large Image | View Hi-Res Image | Download PowerPoint Slide

Enzymes that hydrolyze adenine nucleotides in diabetes and associated pathologies

The activities of the enzymes NTPDase (E.C. 3.6.1.5, apyrase, ATP diphosphohydrolase, ecto-CD39) and 5′-nucleotidase (E.C. 3.1.3.5, CD73) were analyzed in platelets of type 2 diabetic, hypertensive and type 2 diabetic/hypertensive patients. The results showed an increase in platelet NTPDase activity in type 2 diabetic (34% and 72%), hypertensive (32% and 70%) and type 2 diabetic/hypertensive patients (30% and 55%) when compared to control ( P<.01) with ATP and ADP as substrate, respectively. 5′-Nucleotidase activity was elevated in the hypertensive (60%) and type 2 diabetic/hypertensive (53%) groups when compared to the control and type 2 diabetic group ( P<.01). No differences in sensitivity to inhibitors was detected between the platelets of controls and type 2 diabetic/hypertensive patients. No effects on the enzyme activities were observed when pharmacological doses of propranolol, captopril, furosemide, chlorpropamide, acetylsalicylic acid and glibenclamide were administered. Furthermore, changes in platelet adhesiveness and reactivity were found in all groups tested. In conclusion, we may postulate that NTPDase and 5′-nucleotidase from platelets are altered in patients with type 2 diabetes and hypertension. Probably, such alterations are involved in compensatory physiological responses in these diseases and are related to other important mechanisms of thromboregulation.

Platelet adhesion to commercial and modified polymer materials in animals under psychological stress and in a no-stress condition

It is well known that stressful stimuli change blood functions and that protein and platelet parameters are altered in humans and animals subjected to stress. We have examined the influence of psychological stress on the morphological responses of platelets on commercially available materials [polyester (VP), fluoropassivated polyester (VPF), non-woven benzylic ester of hyaluronic acid (Hyaff11)] and on materials synthesised (PUPA) and/or surface modified by sulphation (Hyaff11S) or by immobilisation of the anticoagulant molecules heparin and sulphated hyaluronic acid (PUPA-Heparin, PUPA-HyalS, HyalS-PET). Moreover, the anticoagulant activity (i.e. thrombin inactivation) of the materials was analysed. In the no-stress condition, the surfaces with a low degree of platelet adhesion were Hyaff11S, HyalS-PET, PUPA-Heparin and PUPA-HyalS. Hyaff11, PET and PUPA had the highest number of adherent platelets within the series. VP and VPF exhibited an intermediate behaviour. The exposure of animals to stress induced a dramatic change in platelet number and morphology on PET, HyalS-PET, PUPA, PUPA-HyalS and Hyaff11: there was a higher degree of platelet adhesion, increased platelet spreading and the appearance of pseudopodia. In VP, VPF, Hyaff11S and PUPA-Heparin, there were no changes in platelet adhesion in stress conditions with respect to the no-stress condition; the latter two materials, the only ones able to prolong thrombin time, had a very low number of adherent platelets.

Dietary supplement of omega-3 fatty acids has no effect on acute collagen-induced thrombus formation in flowing native blood.

We have studied the effect of a daily supplement of 2.4 omega-3 fatty acids (omega 3 FAs) to 16 healthy men on acute collagen-induced thrombus formation in flowing non-anticoagulated blood. The supplement was formulated as Triomar capsules, containing 60% omega-3 FAs with an eicosapentaenoic/docosahexaenoic acid ratio of 3/2. A parallel-plate perfusion chamber device was used to study thrombus formation prior to and after 3 months of omega-3 FAs supplement. The wall shear rates at the thrombogenic surface were 650, 2,600 and 10,500 s-1, which are typical for small arteries, slightly stenosed arteries and severely stenosed arteries, respectively. For the latter situation a parallel-plate perfusion chamber with an eccentric stenosis occluding 80% of the cross-sectional area of the blood flow channel was used. The dietary supplement of omega-3 FAs did not cause significant changes in platelet adhesion to collagen or in thrombus volume. However, fibrin deposition was reduced by 34% (P < 0.03) at the highest shear condition (stenosis). Plasma fibrinogen was reduced by 18% (P < 0.0006). Changes in serum concentration of triglycerides, total-cholesterol, LDL- and HDL-cholesterol were not significant. Our data suggest that a moderate intake of omega-3 FAs provides virtually no protection against acute platelet-dependent thrombus formation, irrespective of the shear conditions. However, the significant reduction in plasma levels of fibrinogen following dietary supplementation of omega-3 FAs may be important, since high levels of fibrinogen is associated with cardiovascular disease and thrombosis.

Effect of Fabrication, Sterilization and Mediators - Blood Compatibility of Polyurethanes

The possible changes in the surface and physical properties of polyether urethane urea (PEUU) implants, including their interaction with blood, due to the different preparation methods, sterilization techniques and long term storage in different environmental conditions have been investigated by conducting the studies of mechanical properties, contact angle, platelet adhesion and protein adsorption. Considerable variations in the mechanical properties have been observed for the PEUU grafts stored in different conditions. Changes in platelet adhesion and albumin adsorption have also been observed in the case of samples that underwent different sterilization methods. The effect of mediators like bromelain, an enzyme present in pineapple juice, on albumin adsorption and platelet adhesion on PEUU surfaces have been investigated. It seems the presence of pineapple juice increases the adsorption of albumin and reduces the adhesion of platelets on PEUU surfaces.

Fish Oil: A Potent Inhibitor of Platelet Adhesiveness

Abstract The effect of fish oil administration on platelet function was studied in eight normal individuals, four men and four women, who received fish oil equivalent to 6 g eicosapentaenoic acid per day for a period of 25 days. Platelet aggregation, platelet adhesion, phospholipid and fatty acid distribution were measured at periodic intervals before, during, and after the period of fish oil administration. Platelet aggregation induced by arachidonic acid, adenosine diphosphate, and collagen showed a moderate increase in ED 50 in response to the administration of fish oil. Conversely, platelet adhesion to fibrinogen and collagen I, which was studied at low shear rates in a laminar flow chamber, showed a striking 60% to 65% decrease after fish oil supplementation of the diet. The change in adhesiveness could be correlated with the pseudopodia formed in response to agonistic stimulation. Scanning electron microscopic examination of adherent platelets showed an overall reduction of pseudopodia that appeared short and stubby on fish oil administration. The profile of the fatty acids extracted from plasma confirmed compliance of the volunteers with their dietary supplements. Analysis of phospholipids showed changes in sphingomyelin, lysophosphatidylcholine, and phosphatidylcholine between pseudopodia and platelet cell bodies. Fish oil administration did not affect their overall distribution except for a moderate decrease in phosphatidylethanolamine in platelet pseudopodia. Changes were also recognized in the total fatty acids extracted from platelets, affecting primarily arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid. There were no changes in platelet adhesiveness in a group of five normal individuals who received a vegetable oil supplement of equal dose and duration as that of the fish oil. We conclude from these studies that fish oil, at least when administered over a limited period of time, is an effective inhibitor of platelet adhesiveness.

Fish oil: a potent inhibitor of platelet adhesiveness [see comments

The effect of fish oil administration on platelet function was studied in eight normal individuals, four men and four women, who received fish oil equivalent to 6 g eicosapentaenoic acid per day for a period of 25 days. Platelet aggregation, platelet adhesion, phospholipid and fatty acid distribution were measured at periodic intervals before, during, and after the period of fish oil administration. Platelet aggregation induced by arachidonic acid, adenosine diphosphate, and collagen showed a moderate increase in ED 50 in response to the administration of fish oil. Conversely, platelet adhesion to fibrinogen and collagen I, which was studied at low shear rates in a laminar flow chamber, showed a striking 60% to 65% decrease after fish oil supplementation of the diet. The change in adhesiveness could be correlated with the pseudopodia formed in response to agonistic stimulation. Scanning electron microscopic examination of adherent platelets showed an overall reduction of pseudopodia that appeared short and stubby on fish oil administration. The profile of the fatty acids extracted from plasma confirmed compliance of the volunteers with their dietary supplements. Analysis of phospholipids showed changes in sphingomyelin, lysophosphatidylcholine, and phosphatidylcholine between pseudopodia and platelet cell bodies. Fish oil administration did not affect their overall distribution except for a moderate decrease in phosphatidylethanolamine in platelet pseudopodia. Changes were also recognized in the total fatty acids extracted from platelets, affecting primarily arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid. There were no changes in platelet adhesiveness in a group of five normal individuals who received a vegetable oil supplement of equal dose and duration as that of the fish oil. We conclude from these studies that fish oil, at least when administered over a limited period of time, is an effective inhibitor of platelet adhesiveness.

血せんと脂質に関する研究 Ｖ ＥＰＡの脂質および凝固系におよぼす影響について

The purpose of the study was to investigate the effect of eicosapentaenoic acid (c20: 5, ω3; EPA) on the serum lipids and fatty acid profiles, platelet functions and coagulation systems.Highly concentrated (75%) EPA ethylester, which was isolated and purified from sardine oil, was given to 17 patients suffering from hyperlipoproteinemia and/or hypertension for at least 16 weeks. Daily doses of EPA were 0.9g in 6, 1.8g in 7 and 2.7g in 4 patients. Initial mean total cholesterol level (TC) was 270.9±45.0mg/dl and reduction rates of TC were 4.4% at 4 week-period, 5.8% at 8 week-period, 3.1% at 16 week-period and 6.4% at 12 month-period of the treatment. Triglyceride level fell significantly, 20.9% at 4 week-period, 13.0% at 16 week-period and 18.6% at 12 month-period. HDL-cholesterol did not significantly change throughout the treatment. Changes in plasma main fatty acid profiles were shown in fig 1. plasma EPA increased from 1.84mol% to 5.41mol% after 4 weeks and 4.77mol% after 16 weeks, while other polyunsaturated fatty acids except arachidonate inclined to decrease. Above all, plasma linoleate fell significantly after taking EPA. No correlation between ΔTG and Δlinoleate suggests that exogenous EPA bound mainly to β-position of triglyceride and phospholipids in competition with other polyunsaturated fatty acids.As for platelet functions, no significant changes in platelet adhesiveness and collagen induced aggregation were observed. 1μM ADP induced aggregation lowered from 46.6% in maximal amplitued before the treatment to 29.0% at 16 week-period, 7.1% at 6 month-period and 27.3% at 12 month-period. Over 5mol% of EPA in plasma inhibited ADP induced aggregation. Coagulability expressed by thromboelastogram tended to be reduced, however, prothrombin time, PTT, antithrombin III, α2 macroglobulin and α1 antitrypsin did not alter.In conclusion, EPA reduced both serum lipids and ADP induced aggregation, which would be favourable for the prevention of atherosclerotic thrombotic diseases.

Biochemical and haematological changes during the induction of labour at term with oxytocin, prostaglandin E-2 and prostaglandin F-2alpha.

A total of 75 patients had labour induced near term using intravenous oxytocin, prostaglandin E-2 or prostaglandin F-2alpha. Biochemical and haematological investigations were performed to assess hepatic, renal and adrenocortical function and changes in platelet adhesiveness. In doses which were similarly effective in inducing labour, both prostaglandins were without the water-retaining effect of oxytocin. Adrenocortical stimulation was greatest with oxytocin. No difference between these agents was observed for the other measurements made.

Comparison of the Effects of Various Blood Plasma Expanders on Platelet Adhesiveness

SummaryIn 30 non-anesthetized rabbits, platelet adhesiveness of arterial blood was determined before and 2, 6, and 24 h after 10 min intravenous infusions of either 20 ml isotonic saline solution (5 control rabbits), or 2.4 g each of dextran 40,000 (4 rabbits), dextran 70,000 (4 rabbits), polyvinylpyrrolidone (P. V. P.) 40,000 (8 rabbits), hydroxyethyl starch (H. E. S.) 60,000 (4 rabbits), or H. E. S. 450,000 (5 rabbits) in saline solution.Platelet adhesiveness did not change significantly after infusions of saline, dextran 40,000, or H. E. S. 450,000. In contrast, dextran 70,000 and H. E. S. 60,000 promptly produced about one-third decrease in platelet adhesiveness which returned toward control levels 24 h after the infusions. Finally, P.V.P. also promptly diminished percent platelet adhesiveness by about one-third of control values and this effect persisted 24 h after infusion. Changes in platelet adhesiveness did not correlate with alterations in hematocrit or platelet count.On a weight basis, P. V. P. elicits the most persistent decrease in platelet adhesiveness.

Changes in platelet adhesiveness, blood coagulation and fibrinolysis before and after the development of myocardial infarction. Investigation in 3 cases.

Changes in platelet adhesiveness, blood coagulation and fibrinolysis before and after the development of myocardial infarction. Investigation in 3 cases.

Adhesive Platelet Count and Blood Coagulability in Myocardial Infarction and Cerebral Thrombosis

SummaryIn 382 patients, aged 21 to 76 years, including 39 healthy volunteers, a platelet count by Olef’s method, an adhesive platelet count by Moolten-Vroman’s method, prothrombin activity due to one-stage prothrombin time and calcium clotting time were measured. In 39 cases of myocardial infarction and 40 cases of cerebral thrombosis, both in acute stage, a marked decrease in the adhesive platelet count and adhesive index and an increase of prothrombin activity were observed with statistical significance compared to the healthy group (P &lt; 0.01). In the recovery stage of myocardial infarction, cerebral thrombosis and other diseases, except for malignant tumors, acute infectious diseases, diabetes mellitus and blood or liver diseases, the above observations were absent or reduced. In the case of thrombosis, a negative correlation was seen between the adhesive platelet count and prothrombin activity (r — —0.238, P &lt; 0.01). There is no correlation between the changes in platelet adhesiveness or blood coagulability and total cholesterol level in serum.

PLATELET ADHESIVENESS IN POSTOPERATIVE DEEP-VEIN THROMBOSIS

Changes in platelet adhesiveness, using Wright's (1941) rotating-bulb method, and the development of deep-vein thrombosis detected by the 125I-labelled-fibrinogen-uptake method were studied in fifty patients undergoing surgical operations. Four of the twenty-four patients undergoing general surgical procedures, and thirteen of the twenty-six patients recovering from hip operations, developed postoperative deep-vein thrombosis. Platelet adhesiveness rose in thirty-six patients postoperatively, but no correlation was observed between either preoperative platelet adhesiveness or maximum postoperative platelet adhesiveness and the development of deep-vein thrombosis. There was no significant difference in changes in platelet adhesiveness between those patients who developed deep-vein thrombosis and those who did not. Changes in platelet adhesiveness do not seem to be of value in the prediction or diagnosis of postoperative venous thrombosis.

Postoperative changes in platelet adhesiveness.

Platelet adhesiveness was measured in patients undergoing operation. With the rotating bulb technique adhesiveness increased steadily to the sixth and ninth days following surgery. The glass bead filter technique demonstrated a marked increase in platelet adhesiveness on the day following operation.

Effect of prolonged exercise on platelet adhesiveness.

IT has been established that changes in platelet adhesiveness occur in a variety of physical and physiological conditions. A close investigation of the various physical conditions that affect adhesiveness showed considerable variations in the degree of adhesiveness in eighteen identical observations on the same subject1; there was also slight increase in adhesiveness after feeding. Many methods have been devised to measure stickiness of platelet, and there has been considerable variation in the observations made. This could mean, that different methods are influenced by a number of factors concerned in adhesiveness2. We have investigated the effect of prolonged exercise on platelet adhesiveness. The study was carried out on a group of sixty healthy young adults who were walking from London to Brighton, about 50 miles. The exercise lasted for about 20 h.

Stasis-induced changes in platelet adhesiveness.

Stauung des Blutkreislaufs mit Hilfe einer Druckmanschette (100 mm Hg) am Oberarm verursachte eine Veranderung der Blutblattchenadhasivitat im distal davon gelegenen Bereich des Kreislaufs. Nach einer Stauung von 3 min nahmen die in bezug auf die Hamatokritzunahme korrigierten Adhasivitatswerte zu. Nach einer Stauung von 6 min war eine Ruckkehr der korrigierten Adhasivitatswerte zur Ausgangslage oder auf noch niedrigere Werte feststellbar. Im Blut, welches hauptsachlich aus den grosseren Venen herstammte, und im Blut aus dem Kapillargebiet waren die Veranderungen der Adhasivitat gleichgerichtet, jedoch verschieden gross.