Exercise-induced changes in platelet aggregation; a comparison of whole blood and platelet rich plasma techniques

Studies have been performed to assess the effect of exercise on spontaneous platelet aggregation in shaken whole blood, and on agonist-induced platelet aggregation in whole blood and platelet rich plasma (PRP). Spontaneous platelet aggregation in shaken whole blood was increased following exercise compared to pre-exercise values. The increase in spontaneous aggregation after exercise correlated inversely with the increase in white cell count in whole blood. Platelet sensitivity in whole blood to adrenaline, collagen and adenosine diphosphate (ADP) was increased following exercise. Changes in platelet sensitivity to adrenaline following exercise correlated with increases in plasma noradrenaline levels but not with changes in blood cell counts. In PRP, platelet sensitivity to ADP and to collagen was increased following exercise when the pre and post-exercise PRP platelet counts were not corrected to allow for the increase in platelet count which occurred with exercise. When the PRP platelet counts were corrected, no changes in platelet sensitivity to any agonist after exercise were observed.     

A comparison of spontaneous platelet aggregation in whole blood with platelet rich plasma: additional evidence for the role of ADP

ADP, generated from red blood cells is believed to be responsible for the spontaneous aggregation of platelets in whole blood. This notion is based mainly on the use of enzymes which remove ADP. We have studied spontaneous platelet aggregation in whole blood and autologous platelet rich plasma obtained from 12 healthy male and female volunteers. Platelet aggregation was quantitated by measuring the fall in the number of single platelets counted using a whole blood platelet counter (Ultra Flo 100). In a rotating tube model, the mean fall in the number of platelets due to spontaneous aggregation was 56% in whole blood but, only 3% in platelet rich plasma prepared from the same blood samples. Spontaneous platelet aggregation in whole blood was unaffected by apyrase grade I, but was reduced to 15% by apyrase grade II, to 38% by creatine phosphokinase/creatine phosphate and to 9% by pyruvate kinase/phosphoenolpyruvate. The results of this study provide additional evidence that ADP generated in whole blood triggers the spontaneous aggregation of platelets.     

Fibrinogen, viscosity and white blood cell count predict myocardial, but not cerebral infarction: evidence from the Caerphilly and Speedwell cohort

Fibrinogen, plasma viscocity, and the white blood cell count predict ischaemic heart disease, but there is less certainty for their predictive power for ischaemic stroke. Studying stroke and ischaemic heart disease in the same cohort prospectively allows comparison of predictive strengths. The Caerphilly and Speedwell cohorts consist of a population sample of 4,860 men aged 45-59 years at recruitment who had baseline measurements of fibrinogen, plasma viscosity, and white blood cell counts. After 15-19 years of follow-up, men in the two cohorts experienced 312 ischaemic strokes and 557 ischaemic heart disease events. Mean fibrinogen, plasma viscosity and white blood cell counts differed significantly after adjustment for confounding factors between men with and without ischaemic heart disease, 0.25 g/l (95% CIs 0.1 8-0.32); 0.036 cp (95% CIs 0.027-0.044); 0.67 x 10(9)/l (95% CIs 0.50-0.84) respectively. The same measurements showed no significant differences after adjustment for the same confounding factors for men with and without ischaemic stroke, 0.05 g/l (95% CIs -0.04-0.14); 0.008 cp (95% CIs -0.003-0.019); 0.16 x 10(9)/l (95% CIs -0.06-0.38) respectively.     

The effects of argon laser on in vitro aggregation of platelets in platelet rich plasma and whole blood

The effects of an Argon laser on platelet aggregation were studied, since platelets may be exposed to laser energy when used intravascularly. Various preparations of platelets in platelet rich plasma (PRP) and whole blood, with or without aspirin, were tested with the aggregating agents ADP, collagen, thrombin, and epinephrine. Simultaneous release of ATP was also measured in PRP. At relatively low levels of irradiation, platelet aggregation was potentiated. Enhancement was evidenced by an increase in percent aggregation, earlier onset of the reaction, and reduction in the amount of aggregating agent required. In PRP, the mechanism of laser potentiation appeared to be the release of endogenous ATP from platelets. At relatively high levels of irradiation, platelets were destroyed and aggregation abolished. In whole blood, the mechanism was somewhat more complicated since release of ATP occurred from RBCs as well as platelets. Spontaneous aggregation following laser treatment occurred in isolated instances in PRP and in every trial in whole blood preparations. Aspirin ingestion inhibited the laser's effects in PRP but not in whole blood. These results may have important clinical implications for laser angioplasty, and the potentiated aggregation response may prove useful in laboratory studies of platelet function.     

Recombinant factor VIIa partially reverses the inhibitory effect of fondaparinux on thrombin generation after tissue factor activation in platelet rich plasma and whole blood

Fondaparinux (Arixtra), a specific AT-dependent FXa inhibitor, is effective and safe in the prevention and treatment of venous thromboembolism, but some major hemorrhagic events may occur. No specific antidote to fondaparinux has been proposed. Recombinant FVIIa (Novoseven) could be used as an haemostatic treatment, but this option has not been well documented. We studied the effect of rFVIIa (1 micro g/ml) on the inhibition of thrombin generation induced by fondaparinux (0.1 micro g/ml to 1 micro g/ml). Coagulation was triggered in platelet rich plasma (PRP) or in whole blood by recalcification in the presence of diluted thromboplastin. In PRP thrombin generation was assessed using the thrombinoscope assay. In whole blood, prothrombin activation was assessed by measuring the kinetics of F(1+2) formation using an ELISA assay. Fondaparinux at concentrations equal or greater than 0.5 micro g/ml prolonged the initiation phase of thrombin generation, and reduced the velocity of prothrombin activation. It also decreased by 60% the endogenous thrombin potential. In the presence of fondaparinux (0.5 micro g/ml to 1 micro g/ml) rFVIIa accelerated the initiation phase of thrombin generation, but it did not significantly increase the endogenous thrombin potential. However, rFVIIa did not completely reverse the inhibitory effect of fondaparinux on the parameters of thrombin generation and prothrombin activation. This study shows that rFVIIa accelerates thrombin generation, but does not completely reverse the inhibitory effect of fondaparinux on thrombin generation. The potential clinical use of rFVIIa as haemostatic treatment of major bleedings related to fondaparinux has to be evaluated.     

Effects of adrenaline and alpha adrenergic antagonists on platelet aggregation in whole blood : Evaluation of electrical impedance aggregometry

The effects of adrenaline and alpha adrenergic antagonists on platelet aggregation in whole blood were assessed by electrical impedance. These effects were then compared to those found in platelet rich plasma assessed by both optical and impedance methods. Our data demonstrate a number of difficulties in attempting to measure platelet responsiveness by electrical impedance and re-emphasise the need for caution in interpretation of in vitro platelet aggregation studies in terms of their clinical relevance.     

视神经脊髓炎谱系疾病患者血CD4细胞百分比与肢体伤残的相关性分析

目的探讨视神经脊髓炎谱系疾病(NMOSD)患者血CD4细胞百分比与肢体伤残的关系及其临床意义。方法分析2015年1月-2016年6月上海市第一康复医院及仁济医院神经内科确诊的58例NMOSD患者临床与生化资料,根据扩展残疾状况评分量表(EDSS)将患者分为行走不受限组与受限组,并比较两组患者间的临床、生化特征;分析血CD4细胞百分比与肢体伤残的相关性。结果行走不受限组与受限组之间患者在年龄、脊髓运动症状、自主神经症状及血CD4细胞百分比比较差异有统计学意义(P<0.01);性别、感染因素、视神经症状、脊髓感觉症状、CD3、CD8、CD19、CD4/CD8及NK细胞百分比比较差异无统计学意义(P>0.05);血CD4细胞百分比与肢体伤残呈负相关(r=-0.480,P<0.01)。结论 NMOSD患者入院时血CD4细胞百分比越高,肢体残疾程度越低。血CD4细胞百分比有助于NMOSD患者肢体伤残发生免疫机制的探讨。     

Effect of dipyridamole on spontaneous platelet aggregation in whole blood decreases with the time after venepuncture: evidence for the role of ADP

Spontaneous platelet aggregation (SPA) was studied in human whole blood at 3, 5, 10, 20, 30, 40, and 60 minutes after venepuncture. Using a whole blood platelet counter, SPA was quantified by measuring the fall in single platelet count upon rollermixing aliquots of citrated blood at 37 degrees C. The extent of SPA increased with the time after venepuncture, with a correlation coefficient of 0.819. The inhibitory effect of dipyridamole (Dipy) on SPA was studied: (a) 10 microM at each time interval; (b) 0.5-100 microM at 3 and 30 minutes and (c) 15 microM in combination with 100 microM adenosine, 8 microM 2-chloroadenosine (2Clad, an ADP receptor blocker) and 50 microM aspirin. There was a rapid decrease in the inhibitory effect of Dipy with the time after venepuncture; the correlation coefficient was -0.533. At all the concentrations studied, Dipy was more effective at 3 minutes than at 30 minutes after venepuncture. A combination of Dipy with adenosine, 2ClAd or aspirin was a more effective inhibitor of SPA than either drug alone. However, when 15 microM Dipy and 10 microM Ad were added together, the inhibitory effect of Dipy was not increased significantly, suggesting that Dipy inhibits platelet aggregation independent of Ad. The increase in SPA with the time after venepuncture was abolished when blood was taken directly into the anticoagulant containing 5 microM 2ClAd. It is suggested that ADP released from the red blood cells is responsible for the increased platelet aggregability with the time after venepuncture and makes a serious contribution to the artifacts of in vitro platelet function studies.     

Superoxide dismutase cooperates with prostacyclin to inhibit platelet aggregation: a comparative study in washed platelets and platelet rich plasma.

The role of superoxide anions (O2-) in human platelet aggregation in Krebs' buffer or plasma was investigated. In indomethacin (10 microM)-treated washed platelets superoxide dismutase (SOD; 60 U/ml) or ferricytochrome c (FCC; 70 microM) inhibited platelet aggregation by thrombin but not that by collagen or ADP. In addition, in indomethacin (10 microM)-treated washed platelets, SOD significantly potentiated the anti-aggregatory activity of prostacyclin (PGI2) or iloprost when thrombin but not collagen was used as the aggregating agent. In platelet rich plasma, SOD (60 U/ml) did not inhibit platelet aggregation nor did it potentiate the anti-aggregatory activity of iloprost when ADP, collagen or thrombin were used as aggregating agents. Thus, O2- participate in the aggregatory activity of thrombin but not collagen or ADP and PGI2 or iloprost, by reducing the sensitivity of platelets to thrombin, co-operate with SOD to inhibit thrombin-induced platelet aggregation. The interpretation of the use of SOD in experiments involving endothelium-derived relaxing factor (NO) is discussed.     

Bruising and the ketogenic diet: evidence for diet-induced changes in platelet function

Excessive bruising is a symptom noted by parents of some children treated with the ketogenic diet for epilepsy control, although this side effect is not reported in the literature. We evaluated our cohort of current and past diet-treated patients for symptoms of bruising or bleeding through chart review and prospective screening at clinic follow-up visits. A significant increase in bruising or other minor bleeding was reported and/or observed in 16 of 51 patients (31.4%). There were no differences in sex distribution or number of anticonvulsants used between patients with bruising/bleeding and those without this symptom, although the group with bruising/bleeding was significantly younger. No specific anticonvulsant was associated with bruising/bleeding. Six patients with diet-induced bruising/bleeding underwent an investigation for bleeding diathesis. Five of these patients had prolonged bleeding times and all had diminished responsiveness to various platelet aggregating agents, with no evidence of a release defect. The abnormalities all normalized in the 1 patient tested after ceasing the diet. No patients had serious hemorrhage. One patient had mild von Willebrand disease, which had been asymptomatic before diet initiation. Some patients were Stimate responsive, suggesting a treatment for more severe bouts of symptoms. These data suggest that a ketogenic diet-related bleeding tendency occurs in about one third of treated patients owing to preexisting factors defining susceptibility in combination with diet-induced depression of platelet responsiveness, possibly related to changes in platelet membrane lipid composition and/or concentration and resultant effects on function of membrane-embedded proteins. Patients on the diet undergoing anticoagulation or surgery should be evaluated carefully for symptoms of bleeding tendency.     

Plasma DBH, platelet MAO and proteins of red blood cell membranes in individuals with variants of the normal EEG

Plasma DBH, platelet MAO and proteins of red blood cell membranes were examined in healthy male carriers of variants of the normal resting EEG. The variants included low-voltage EEG, badly synchronized alpha-EEG, diffuse beta-EEG and monotonous alpha-EEG. Mean DBH activity of the low-voltage EEG group was only half that of the monotonous alpha-EEG group. No difference between EEG types in platelet MAO activity and in polypeptide pattern of erythrocyte membranes after electrophoresis could be detected.     

Pharmacoclinical strategy in neuroleptic resistant schizophrenic patients treated by clozapine: clinical evolution, concentration of plasma and red blood cell clozapine and desmethylclozapine, whole blood serotonin and tryptophan.

1. The aim of the study was to determine if a more rational therapeutic approach could be devised for neuroleptic resistant psychotic patients treated for months and years with clozapine. Clozapine is an atypical antipsychotic medication, but its therapeutic benefit has been limited by a high incidence of agranulocytosis and seizures. 2. The study has been performed in an open setting and included 12 patients. Some of them developed a secondary depression and were treated with fluoxetine. 3. Pharmacokinetic analysis were conducted at the same time as clinical evaluations, grading using the BPRS, the PDS, and QLS, and determinations of plasma and red blood cell clozapine and desmethylclozapine, plasma and RBC fluoxetine and norfluoxetine, whole blood serotonin and tryptophan. 4. A positive linear correlation was found only between RBC concentration and the evolution of the QLS. 5. Clozapine is efficacious both on positive and negative symptoms but its mechanism of action remains unclear. Positive symptoms disappear more quickly, sometimes followed by a post psychotic depression. Negative symptoms improve more slowly but regularly. They seem to be correlated with serotoninergic mechanisms. For whole blood 5HT, an important increase was seen about 4 weeks after Cloza administration, and then a decrease. 6. Therapeutic drug monitoring (on the same sample drawn for haematological monitoring providing) could play a useful role in the management of patients treated by clozapine: compliance, lowest dose, possible toxicity, drug interaction, lack of efficacy, relapse predictivity.     

Polymorphonuclear leukocyte and monocyte activation induced by plasma from patients with heparin-induced thrombocytopenia in whole blood

Heparin-induced thrombocytopenia (HIT), a severe complication of heparin therapy, results from platelet activation by heparin-dependent antibodies. Previously, we have shown that plasma from patients with HIT (HIT plasma) induces leukocyteplatelet aggregation in blood. In this report, we examined leukocyte activation by HIT plasma and the contribution of heparin and platelets to this activation, in whole blood. Degranulation of leukocytes from HIT patients was evaluated as a leukocyte activation marker. We showed that polymorphonuclear leukocytes (PMN) and monocytes were the leukocyte subpopulations involved in platelet-leukocyte aggregation induced by HIT plasma in healthy donor blood. PMN and monocyte activation, reflected by increased surface expression of the CD11b adhesion molecule, was induced by HIT plasma in a heparin-dependent manner. The CD11b increase induced by HIT plasma was observed on PMN only when they were associated with platelets. Moreover, the increased CD11b expression on monocytes and PMN correlated strongly with the degree of platelet adhesion to these cells. Degranulation of leukocytes from HIT patients and control subjects (non-HIT heparin-treated patients and healthy subjects) was evaluated in vivo by measuring the plasma myeloperoxidase concentration. HIT plasma contained higher myeloperoxidase concentrations than control plasma, suggesting leukocyte degranulation during HIT. In conclusion, this study provides the first evidence that PMN activation is induced by HIT plasma. HIT plasma induced PMN and monocyte activation in a heparin-dependent manner. In whole blood, platelet association with monocytes and PMN, and the activation of these leukocytes by HIT plasma were interrelated. Finally, leukocyte degranulation could be involved in HIT physiopathology.     

The effect of aspirin on the exercise-induced changes in platelet function and blood coagulation

In a study of 10 normal subjects, administration of aspirin was shown to prevent exercise-induced increases in platelet aggregation to collagen and adrenaline. The exercise-induced rise in the plasminogen-activator content of plasma euglobulin precipitates was also reduced by aspirin, whereas rises in platelet count, factor VIII levels and decrease in partial thromboplastin time of plasma were unaffected.The prevention by aspirin of exercise induced increases in platelet aggregation, in the light of the possible involvement of platelets in thromboembolic disease, suggest that further study of the therapeutic usage of aspirin in treatment of this disease is merited.     

The effect of plasma on platelet function in hypercholesterolemic rabbits and the changes in fatty acid composition of the plasma

Rabbits were fed with 1% cholesterol-containing standard diet for 1 to 3 months. The arachidonic acid (AA)-induced aggregation of the platelet-rich plasma (PRP) of the control rabbits was accelerated by substitution of hypercholesterolemic plasma. The incorporation of C-AA into thromboxane B₂ in platelets was increased approximately 1.6 times with PRP and 1.2 times with the washed platelet suspension (WPS) in hypercholesterolemic rabbits as compared with those of the control. Analysis of the fatty acid compositions of phospholipids and total lipids of hypercholesterolemic rabbits revealed an increase in AA of platelets and plasma, and a decrease in docosahexaenoic acid (DHA) in plasma. The AA/DHA ratio of plasma increased dependently on the period of feeding with the high cholesterol diet, and the increase in the ratio was parallel with the acceleration of platelet aggregation by AA in PRP.     

Case reports and literature review: the association between reactivation of human herpes virus-6 and peripheral white blood cell count in patients with carbamazepine-induced hypersensitivity syndrome

Eruptions induced by anticonvulsants can often be experienced clinically, and the clinical diagnosis of "drug induced hypersensitivity syndrome (HS)" was proposed to characterize these drug eruptions. Reactivation of human herpes virus-6 seems to be an integral component of HS. Previously, we experienced two cases of carbamazepine (an anticonvulsant) induced HS and both cases did not show a reactivation of human herpes virus-6 infection (no elevation of anti-human herpes virus-6 IgG titres). The features of these two cases were compared with other reported cases that presented HS with the reactivation of human herpes virus-6. In the early phase of HS, a change in peripheral white blood cell count seems to be important and could be used as an indicator to predict whether late phase HS with reactivation of human herpes virus-6 will occur, since the increase in white blood cell count is seen before the increase in anti-human herpes virus-6 titres. Reactivation of human herpes virus-6 may cause severe clinical symptoms such as encephalitis. When an increase in white blood cells are observed in HS cases at onset, immediate discontinuation of cause drug and intensive care are necessary to avoid the more severe symptoms of HS.