Plasma beta-thromboglobulin values in thrombocytopenic patients with acute leukemia

Plasma beta-thromboglobulin (beta-TG) levels were measured in 14 healthy subjects and in 20 acute leukemia (AL) patients, newly diagnosed, with highly variable values for venous platelet counts. For healthy subjects the plasma beta-TG levels ranged 12-38 (mean 17) ng/ml. In this group of patients with AL, a highly significant positive correlation (P < 0.001) between the values for plasma beta-TG and venous platelet count was present. During a thrombocytopenic period, the plasma beta-TG concentraton was measured in nine of the AL patients immediately before and 10 to 12 hours after platelet transfusion therapy. Fourteen platelet transfusions were administered when the patient's highest temperature of the day was < 38.5 degrees C, and 18 when the highest temperature of the day was greater than or equal to 38.5 degrees C. The mean pre-transfusion and post-transfusion beta-TG values for the 14 platelet transfusions were 7 +/- 2 and 20 +/- 5 ng/ml, respectively. The corresponding means for the 18 transfusions given to febrile patients were 5 +/- 2 ng/ml and 11 +/- 2 ng/ml, respectively. Of the pretransfusion values, 11/14 and 14/18 were below the control range. We conclude that the plasma beta-TG values are considerably lower in thrombocytopenic patients than in subjects with normal platelet counts. Further work should provide reference values for plasma beta-TG over a wide range of venous platelet counts.     

Plasma beta-thromboglobulin and platelet factor 4 concentrations in patients with atrial fibrillation

The clinical significance of beta-thromboglobulin (beta-TG) and platelet factor 4 (PF-4) levels were evaluated in 26 patients with atrial fibrillation (af) complicated by valvular heart disease (VHD), 73 patients with af but without valvular heart disease and 57 normal subjects. The beta-TG level was significantly higher in af patients without VHD than in normal subjects (49.4 +/- 35.8 ng/ml vs 31.2 +/- 14.0 ng/ml, p less than 0.01) and in af patients with VHD than in normals (64.1 +/- 52.8 ng/ml vs 31.2 +/- 14.0 ng/ml, p less than 0.01). Af patients with or without VHD tended to show high levels of PF4 compared with normals (af patients without VHD: 34.1 +/- 45.5 ng/ml, af patients with VHD: 18.6 +/- 27.2 ng/ml, normals: 11.6 +/- 8.2 ng/ml). There was no correlation between beta-TG levels and age in af patients without VHD or in normals. There was also no correlation between beta-TG levels and heart rate in af patients without VHD. The activation of platelets was suggested in patients with atrial fibrillation on the basis of increased levels of platelet releasing substances, especially in those with VHD. The high levels of beta-TG and PF4 in patients with atrial fibrillation may be one explanation for the high incidence of thromboembolism in these patients, indicating the necessity of antiplatelet therapy.     

Effect of short-term hypoxia on blood platelet function tests of normal subjects

We studied how smoking and hypoxia affected blood platelet functions. Eighteen normal subjects (ten nonsmokers and eight smokers) inspired 13% oxygen gas and underwent platelet function tests (blood platelet count, MPV, maximum platelet aggregation rate, plasma beta-TG, plasma PF-4) measured just before inspiration and 30 minutes and 60 minutes after inspiration of the gas. Four principal results were obtained. First, breathing room air, blood platelet count and maximum platelet aggregation rate of smokers were significantly increased compared to those of non-smokers. Second, platelet counts and MPV were not affected by hypoxia in either group. Third, the maximum platelet aggregation rate of smokers was significantly decreased by hypoxia. Fourth, in both groups, the plasma levels of beta TG and PF-4 were decreased 30 minutes after inspiration of the 13% oxygen gas. In non-smokers, 60 minutes after inspiration, these plasma levels recovered to the primary levels. Our study showed that blood platelet functions of normal subjects were affected by hypoxia, and the effects of hypoxia on these functions in these two groups were markedly different.     

Comparison of the effects of cellulose triacetate and polysulfone membrane on GPIIb/IIIa and platelet activation

BACKGROUND: During hemodialysis session, several adverse reactions can occur on platelets, which are attributable to bioincompatibility of the dialysis membrane. Glycoprotein IIb/IIIa (GPIIb/IIIa) is the receptor for fibrinogen, which mediates platelet aggregation and adhesion. Accordingly, we compared the influence of a cellulose triacetate (CTA) and polysulfone (PS) membrane on GPIIb/IIIa and platelet activation. METHODS: Blood samples from 5 patients on hemodialysis were taken at 0 time, 15 min, 30 min, 60 min and 240 min, during a single hemodialysis session, by a crossover design using CTA or PS. Platelet count and plasma concentration of GPIIb/IIIa, beta-thromboglobulin (beta-TG) and platelet factor 4 (PF-4) were measured. GPIIb/IIIa was measured by flow cytometry. beta-TG and PF-4 were measured by ELISA. RESULTS: There was no significant change in the total amount of GPIIb/IIIa during dialysis session between the CTA and PS. However, the level of bound GPIIb/IIIa was significantly (p < 0.0002) increased from 1,426 +/- 435 to 40,446 +/- 2,777 mol/PLT with PS. In contrast, there was no significant change with CTA (3,258 +/- 1,469 to 4,301 +/- 1,422 mol/PLT). The platelet counts and beta-TG and PF-4 behavior during the dialysis session did not show significant change between the PS and CTA. CONCLUSION: The characterization of changes in platelet membrane receptor (GPIIb/IIIa) may be a useful marker for studying the biocompatibility of dialysis membranes. On platelet aggregation, CTA might be more biocompatible membrane than PS.     

Increased platelet activity in patients with isolated coronary artery ectasia

BACKGROUND: The common coexistence with coronary artery disease has led to the suggestion that coronary artery ectasia (CAE) is a variant of coronary artery disease. The mechanisms, however, responsible for CAE formation during the atherosclerotic process and the exact clinical significance are not well known. In this study, we aimed to investigate platelet activity in patients with isolated CAE by using specific markers of platelet activation as P-selectin, beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4). METHODS: Thirty-two patients with isolated CAE without significant stenosis and 30 control participants with angiographically normal coronary arteries were included in this study. According to the angiographic definition used in the Coronary Artery Surgery Study, a vessel is considered to be ectasic when its diameter is > or = 1.5 times that of the adjacent normal segment in segmental ectasia. Plasma P-selectin, beta-TG and PF4 levels were measured in all patients and control participants using enzyme-linked immunosorbent assay method. RESULTS: Patients with isolated CAE were detected to have significantly higher levels of plasma P-selectin, beta-TG and PF4 in comparison with control participants with angiographically normal coronary arteries (P-selectin: 248+/-46 vs. 154+/-32 ng/ml, respectively, P<0.001; beta-TG: 51+/-19 vs. 21+/-9 ng/ml, respectively, P<0.001; PF4: 58+/-23 vs. 33+/-11 ng/ml, respectively, P<0.001). CONCLUSION: In conclusion, we have shown for the first time that patients with isolated CAE have raised levels of plasma P-selectin, beta-TG and PF4 compared with control participants with angiographically normal coronary arteries, suggesting increased platelet activation in patients with CAE.     

Plasma beta-thromboglobulin to platelet factor 4 ratios as indices of vascular complications in essential hypertension

The ratio of the plasma level of beta-thromboglobulin (beta-TG) to platelet factor 4 (PF-4) which is regarded as a most reliable indicator of platelet activation in vivo, was followed in 52 subjects at various stages of essential hypertension according to the WHO classification. These comprised 30 cases at stage I, 19 cases at stage II and three cases at stage III, and 20 age-matched normotensive control subjects. The observed beta-TG:PF-4 ratio in the hypertensive patients was 4.59 +/- 0.20, which was significantly higher than the value of 3.13 +/- 0.19 recorded in the normotensive control subjects. According to the WHO classification, beta-TG:PF-4 ratios in hypertensive patients at stages I, II and III were 3.93 +/- 0.19, 5.31 +/- 0.35 and 6.56 +/- 0.12, respectively. The beta-TG:PF-4 ratio revealed a tendency of platelet activation to increase with advanced progress of hypertensive vascular lesions. These results suggest that the abnormal platelet function observed in patients with essential hypertension plays an important role in the development of hypertensive vascular complications.     

Beta-thromboglobulin and platelet factor 4 in polycythemia patients treated by ticlopidine

34 polycythemic patients, in complete or partial stable remission, were studied for beta-thromboglobulin (beta-TG) and platelet factor 4 (PF-4) before, during and after treatment by an antiaggregating agent, ticlopidine, in comparison with 30 untreated patients. The cases with initial high value have an obvious drop, which is still maintained at the 2nd month after treatment, independent of variations of red cell and platelet counts. Any long-term protocol for clinical evaluation of antiaggregating therapy in myelo-proliferative diseases should be founded on evaluation of the markers of platelet function.     

Increased blood coagulation and platelet activation in patients with infective endocarditis and embolic events

BACKGROUND: Inflammation-induced procoagulant changes and alterations in platelet activity appear to play an important role in thromboembolic complications of infective endocarditis (IE). HYPOTHESIS: The aim of this study was to investigate systemic coagulation activity, fibrinolytic capacity, and platelet activation in patients with IE with and without embolic events by measuring the plasma levels of prothrombin fragment 1+2 (PF1+2), thrombin-antithrombin III complex (TAT), plasminogen activator inhibitor-1 (PAI-1), beta-thromboglobulin (beta-TG), and platelet factor 4 (PF4), respectively. METHODS: The study included 76 consecutive patients (female = 55, male = 21, mean age 26 years, range 8-64 years) with definite IE according to the Duke criteria; of these, 13 (17.1%) had embolic events. RESULTS: Plasma concentrations of PF1+2 (3.2 +/- 1.3 vs. 1.7 +/- 0.7 and 1.4 +/- 0.7 nmol/l, p < 0.001, respectively) and TAT (7.3 +/- 1.5 vs. 2.9 +/- 1.2 and 2.2 +/- 1.1 ng/ml, p < 0.001, respectively) were elevated in patients with embolic events compared with patients without embolic events and control subjects. Similarly, patients with embolic events had increased plasma levels of beta-TG (63.3 +/- 10.9 vs. 33.1 +/- 11.6 and 19.1 +/- 10.6 ng/ml, p < 0.001, respectively) and PF4 (106.0 +/- 28.7 vs. 50.3 +/- 16.7 and 43.0 +/- 15.8 ng/ml, p < 0.001, respectively) compared with those without embolic events and the control group. Embolic patients also had higher PAI-1 levels than nonembolic patients and healthy subjects (14.4 +/- 6.4 vs. 8.6 +/- 5.9 and 5.4 +/- 4.3 ng/ml, p = 0.002, respectively). CONCLUSION: Patients with IE and with subsequent thromboembolism have increased systemic coagulation activation, enhanced platelet activity/damage, and impaired fibrinolysis. The resulting imbalance produces a sustained hypercoagulable state, which contributes to the increased risk of thromboembolic events in this particular group.     

Plasma Concentrations of Platelet Factor 4 in Acute Myocardial Infarction

The aim was to investigate whether in the acute stage of myocardial infarction (MI) platelet activation, as measured by plasma platelet factor 4 (PF-4), excluding that in ischaemic heart disease (IHD) is taking place. Over a period of 4 d the plasma levels of PF-4 were determined on 44 consecutive patients admitted to a coronary care unit with suspected MI. 21 of them had a definite acute MI (group 1), and 13 had evidence of IHD but no MI (group 2). In the remaining 10 subjects there was no evidence of either MI or IHD. On the first day the mean plasma PF-4 concentrations in group 1 and 2 patients were 11.8 ± 1.1 and 15.0 ± 2.3 ng/ml, respectively; the difference between means was not statistically significant. A peak mean PF-4 for group 1 patients (17.5 ± 4.6 ng/ml) was recorded on the second day of study. The corresponding value for group 2 patients was lower, but not significantly so. In the latter subjects no peak PF-4 was recorded. During the last 2 d of study the plasma PF-4 concentrations tended to decrease, but the means for the 2 groups did not differ statistically. Thus, at no point in time was there a significant difference between the PF-4 values for MI and IHD patients present.     

Deep vein thrombosis and related platelet changes after total hip replacement

Postoperative changes related to platelets and their correlation with the incidence of deep venous thrombosis (DVT) were studied in 30 patients undergoing total hip replacement. Levels of platelet count, platelet-crit, mean platelet volume, spontaneous platelet aggregation, platelet factor 4 (PF4) and beta-thromboglobulin (beta-TG) were measured before operation and on the 1st, 3rd and 7th postoperative days. DVT was detected by 125I-fibrinogen leg scanning in 11 of the patients. After the operation there was a significant and progressive increase (p less than 0.01) in PF4 and beta-TG, and the presence of circulating platelet aggregates was demonstrated. Platelet count levels and platelet-crit were decreased on the 1st and 3rd postoperative days followed by recovery on the 7th day. The changes observed following total hip replacement were not related to the development of postoperative DVT.     

Platelet aggregation and thromboxane A2 production after adrenergic stimulation in young healthy humans

The effects of adrenergic stimulation on platelet aggregation (platelet aggregation ratio; PAR), beta-thromboglobulin (beta-TG) release and plasma thromboxane B2 (TxB2) levels were investigated in 25 healthy young volunteers. Adrenergic stimulation induced by cold application was checked by evaluating the changes in the calculated vascular resistance in the forearm. A prompt increase in platelet aggregates and plasma beta-TG and TxB2 concentrations was observed after adrenergic stimulation. PAR changed from resting values of 0.97 +/- 0.05 to 0.75 +/- 0.08 (p less than 0.001) at the end of cold application. At the same time, beta-TG plasma concentration increased from 32.09 +/- 19.64 to 135.48 +/- 37.97 ng/ml (p less than 0.001) and TxB2 plasma levels changed from 0.49 +/- 0.24 to 0.99 +/- 0.39 pmol/ml (p less than 0.001). TxB2 levels, but not PAR and beta-TG concentration came back to the resting values at the end of the observation period (10 min). Aspirin, as the lysine acetylsalicylate equivalent to 5 mg/kg i.v. of acetylsalicylic acid, although able to completely inhibit platelet cyclooxygenase failed to inhibit the plasma TxB2 increase induced by adrenergic stimulation. This strongly suggests that the increase in plasma TxB2 following adrenergic stimulation is of extraplatelet origin. Also beta-TG and PAR changes were not affected by aspirin administration.     

Effects of varying dietary fatty acid ratios on plasma lipids and platelet function in the African green monkey

The influence of varying dietary fatty acid ratios on plasma lipids, platelet function and the potential for thrombosis was evaluated in the African green monkey (Cercopithecus aethiops), an animal model widely used in cardiovascular research. Ten adult animals, 5 males and 5 females, at intervals of 2 months, were fed a series of 7 diets with fatty acid ratios (P:S) ranging from 3:1 to 1:4. Platelet aggregation in vitro, plasma levels of beta-thromboglobulin and platelet factor 4, platelet membrane fatty acid composition and plasma lipids including total cholesterol, HDL and LDL were monitored at the end of each dietary period. Platelet hypersensitivity to ADP aggregation (3 and 10 microM) and plasma beta-thromboglobulin were elevated in both males and females when dietary P:S exceeded 1.5:1 (beta-TG = 45 ng/ml) as compared to control diets either reflecting current North American or that recommended as a desirable dietary goal (P:S = 1:1, beta-TG = 10 ng/ml). Diets enriched in saturated fatty acids (P:S = 1:2) also altered platelet function, but the effects were most consistently observed in female animals (beta-TG = 32 ng/ml). Platelet hypersensitivity was lost and beta-TG levels were at baseline when the animals were returned to the control diets. Platelet sensitivity did not correlate with membrane composition which generally reflected dietary composition. Both the saturated and the polyunsaturated fatty acid enriched diets lowered plasma HDL levels, and the saturated fatty acid diets elevated plasma LDL.(ABSTRACT TRUNCATED AT 250 WORDS)     

Elevated beta thromboglobulin in peripheral venous blood of patients with acute myocardial ischemia: direct evidence for enhanced platelet reactivity in vivo

Levels of beta thromboglobulin, a platelet-specific protein, in platelet-poor plasma from peripheral venous samples of patients with acute myocardial ischemia were measured in order to obtain direct evidence for enhanced platelet reactivity in vivo in these patients and to determine the value of beta thromboglobulin assay in studying platelet reactivity in patients with ischemic heart disease.The normal beta thromboglobulin concentration in peripheral venous plasma, determined from normal volunteers and patients without known ischemic heart disease or disorders associated with enhanced platelet destruction (control group without platelet destruction), was 30.0 ± 12.6 ng/ml (mean ± standarddeviation) (range 10 to 59). The mean beta thromboglobulin level in hospitalized patients with chest pain judged not to be due to acute myocardial ischemia was 33.7 ± 12.0 (range 11 to 65). Patients with deep venous thrombosis, disseminated intravascular coagulation, thrombotic thrombocytopenic purpura and idiopathic thrombocytopenic purpura provided a control group of patients with enhanced platelet destruction; the beta thromboglobulin level in this group was 131.0 ± 12.6 ng/ml (range 38 to 250).Elevated beta thromboglobulin levels were observed in 4 (16 percent) of 25 patients with stable angina pectoris (mean 45.0 ± 22.6 ng/ml, range 22 to 125), in 23 (59 percent) of 39 patients with unstable angina pectoris (mean 83.2 ± 73.7 ng/ml, range 14 to 910) and in 12 (80 percent) of 15 patients with acute myocardial Infarction (mean 118.5 ± 66.2 ng/ml, range 30 to 420) on one or more occasions during hospitalization. The mean values of patients with platelet destruction in the control group (p <0.001), patients with acute myocardial infarction (p <0.005) and patients with unstable angina pectoris (p <0.025) were significantly elevated with respect to values in patients without platelet destruction in the control group. The beta thromboglobulin levels of patients with acute myocardial infarction generally remained elevated during the first 3 to 4 hospital days.Elevation of beta thromboglobulin levels in patients with acute myocardial ischemia provides direct evidence for enhanced platelet reactivity in these patients. However, the temporal relation of the elevated beta thromboglobulin values with clinical deterioration was imprecise, so that it can not be determined from this study whether the enhanced platelet reactivity was a cause or an effect of the acute myocardial ischemia in these patients. Assay of beta thromboglobulin appears to be suitable as an indicator of enhanced platelet reactivity in patients with ischemic heart disease. Its use obviates many of the difficulties in interpretation of the various in vitro analyses of platelet function and platelet survival studies.     

Characterization of five marker levels of the hemostatic system and endothelial status in normotensive pregnancy and pre-eclampsia

OBJECTIVES: Pre-eclampsia is associated with changes in the hemostatic system and endothelial status. Urinary 11-dehydrothromboxane B2/creatinine (11-DTXB2/Cr) is a marker for platelet activation and vascular constriction, thrombin-antithrombin complex (TAT) for thrombin formation, serum thrombomodulin (TM) for endothelial damage, and beta-thromboglobulin (beta-TG) and platelet factor 4 (PF-4) for platelet activation and releasing reaction. The present study attempted to evaluate these five markers in normotensive pregnancy and pre-eclampsia. METHODS: These five markers were simultaneously measured in urine and blood samples from 25 women who were not pregnant (group 1, controls), 31 women with normotensive pregnancy (group 2, second controls), 22 women with mild pre-eclampsia (group 3), and 21 women with severe pre-eclampsia (group 4). The average gestational age was 36 wk. RESULTS: The 11-DTXB2/Cr, TAT, and beta-TG levels were significantly higher (P < 0.01) in groups 2, 3, and 4 than in group 1. The TM and beta-TG levels were significantly higher (P < 0.05) in group 3 than in group 2. The TM, beta-TG, and PF-4 levels were increased significantly (P < 0.05-0.01) in group 4 compared to those in groups 1, 2, and 3. CONCLUSION: Platelet aggregation, vascular constriction, and thrombin formation (detected by 11-DTXB2/Cr and TAT) may be markedly enhanced even in group 2, but further enhancement may be relatively slight in groups 3 and 4. In contrast, endothelial damage (determined by TM) and platelet release of PF-4 may not increase significantly in group 2, but they may increase in group 4. Platelet-release of beta-TG may be enhanced in groups 2, 3, and 4. Endothelial damage and platelet-releasing reaction (detected by PF-4 and beta-TG) may be significantly more enhanced in group 4 than in group 3.     

Plasma Levels of Platelet Factor 4 in Patients Admitted to a Coronary Care Unit

Blood was obtained from 63 consecutive patients within a 24 h period after the admission to a coronary care unit for the determination of plasma platelet factor 4 (PF-4) concentration. 28 of the subjects proved to have an acute myocardial infarction (MI), 24 had evidence of ischaemic heart disease (IHD) but no MI, and the remaining 11 patients had no signs of IHD. 40 healthy subjects served as controls. The mean PF-4 value in the MI group was 10.5 ±0.8 ng/ml. The corresponding values for patients with and without IHD were 8.7 ±0.6 and 8.3 ±0.6 ng/ml, respectively. The control mean (5.4 ±0.3 ng/ml) was significantly lower (P < 0.001) than the means for all 3 groups of patients studied. The difference between the group of MI patients and patients with IHD as well as patients without IHD was only of borderline significance (0.10 > P > 0.05).     

Human platelet factor 4: Preparation from outdated platelet concentrates and application in cerebral vascular disease

Platelet factor 4 (PF4), the platelet antiheparin protein, was isolated from both the supernatant and the cells of recently outdated platelet concentrates. Following purification by affinity chromatography, a competitive binding radioimmunoassay was developed to detect this protein in human plasma. The normal range was determined to be 9.4 ± 4.7 ng/ml (mean ± SD for 52 healthy adults). In order to determine whether individuals with transient ischemic attack (TIA) or stroke had measurable increments of PF4 in their plasma, radioimmunoassay studies were performed on 11 patients with well-documented TIA, 10 patients with well-documented stroke and on 16 age-matched controls hospitalized on a neurology service with disorders unrelated to arterial thrombosis. The 16 hospitalized controls had PF4 levels of 10.3 ± 9.1 ng/ml, a value not significantly different from the 52 normals (P > 0.50). Patients with TIA had PF4 levels of 24.6 ± 12.1 ng/ml, a value significantly higher than both the 52 normals (P < 0.001) and the 16 hospitalized control patients (P < 0.005). Patients with stroke had PF4 levels of 35.4 ± 29.2 ng/ml, a value significantly higher than both the 52 normals (P < 0.001) and the 16 hospitalized control patients (P < 0.005). Outdated platelet concentrates facilitate the development of a reproducible radioimmunoassay for PF4. The elevation of this platelet-derived protein in the plasma of patients with stroke and TIA provides evidence for recent or ongoing platelet activation in the cerebral vascular disease population.     

Increased platelet activation in young patients with prehypertension

Mean platelet volume (MPV) and sP-selectin levels are considered as indicators of platelet activation. In this study, we assessed platelet activation in prehypertensive patients by comparing MPV and sP-selectin levels of these patients with healthy conrols. The study population consisted of 25 newly diagnosed prehypertensive individuals (18 men, mean age = 34 ± 6 y) and 25 healthy control subjects (16 men, mean age = 33 ± 6 y) eligible for the current study. Blood pressure (BP) , lipid profile, plasma glucose, HOMA-IR values, sP-selectin levels, platelet counts, and MPV were measured in both groups. Other than systolic blood pressure (SBP) and diastolic blood pressure (DBP), baseline demographic characteristics of both groups were similar. No significant difference was found between the platelet counts of the two groups. Despite comparable platelet counts, platelet activation parameters were found significantly higher in the prehypertensives. Prehypertensives had larger a MPV value compared to that of the control group (8.24 ± 0.46 fl vs. 7.70 ± 0.64 fl; P = 0.001) and plasma sP-selectin levels were also significantly higher in the prehypertensive patients (163.60 ± 41.21 ng/ml vs. 132.80 ± 36.46; P = 0.007). Spearman correlation analysis revealed moderate positive correlation between SBP and platelet activation parameters (for SBP and MPV, r = 0.60, p = 0.001; for SBP and sP-selectin r = 0.51, p = 0.009). Prehypertension causes platelet activation as evidenced by increased MPV and plasma sP-selectin levels. Increased platelet activation might be related to increased vascular thrombotic risk in those patients.     

A prospective study of G-CSF effects on hemostasis in allogeneic blood stem cell donors.

Granulocyte colony-stimulating factor (G-CSF) is used in healthy donors of peripheral blood stem cells (PBSC) for allogeneic transplantation. However, some data have recently suggested that G-CSF may induce a hypercoagulable state, prompting us to study prospectively 22 PBSC donors before and after G-CSF 5 microg/kg twice daily. We sought evidence for changes in the following parameters: platelet count, von Willebrand factor antigen (vWF:Ag) and activity (vWF activity), beta-thromboglobulin (beta-TG), platelet factor 4 (PF-4), platelet activation markers (GMP-140 and PAC-1), activated partial thromboplastin time (aPTT), prothrombin time (PT), coagulant factor VIII (FVIII:C), thrombin-antithrombin complex (TAT), prothrombin fragment 1+2 (F1+2), thrombomodulin (TM) and tissue plasminogen activator antigen (tPA:Ag) prior to G-CSF and immediately before leukapheresis. ADP-induced platelet aggregation studies were also performed. G-CSF administration produced only mild discomfort. We found a significant increase in vWF:Ag (from 0.99 +/- 0.32 U/ml to 1.83 +/- 0.69 U/ml; P < 0.001), in vWF activity (from 1.04 +/- 0.34 U/ml to 1.78 +/- 0.50 U/ml; P < 0.001) and in FVIII:C (from 1.12 +/- 0.37 U/ml to 1.73 +/- 0.57 U/ml; P < 0.001) after G-CSF. Of note, four donors with low baseline vWF had a two- to three-fold increase after receiving G-CSF. G-CSF had no impact on the platelet count, beta-TG, PF-4, GMP-140 or PAC-1. The final% of platelet aggregation decreased from 73 +/- 22% to 37 +/- 26% after G-CSF (P < 0.001). We found a significant decrease in aPTT after G-CSF (29.9 +/- 3.1 s to 28.3 +/- 3.3 s; P = 0.004), but the PT was unaffected. In addition, we also observed a significant increase in TAT, F1+2 and TM, but not in tPA:Ag. Our data suggest that G-CSF may possibly induce a hypercoagulable state by increasing levels of FVIII:C and thrombin generation. In contrast to this information, we found reduced platelet aggregation after G-CSF administration. The clinical implications of these findings remain unclear and larger studies are definitely required.     

Defective platelet aggregation and increased platelet turnover in patients with myelofibrosis and other myeloproliferative diseases

In 9 patients with myeloproliferative diseases (MPD) (6 with myelofibrosis, MF, 1 with Ph1 positive chronic granulocytic leukaemia, CGL, 1 with primary eosinophilia, PE, 1 with pre-leukaemia syndrome, preL) collagen, epinephrine, and ADP-induced aggregation, N-ethylmaleimide-induced malondialdehyde (MDA) production, beta-thromboglobulin (beta-TG) plasma levels, and platelet turnover were studied. Collagen-induced aggregation was found to be normal in 7 patients, absent in 1, and reduced in 1. In all but 3 patients, aggregation with ADP was markedly reduced. Epinephrine-induced aggregation was decreased in 7 patients. No difference was found between mean MDA production in MPD (3.21 +/- 0.50 nmol/10(9) PLTs) and in control group of 21 normal subjects (3.04 +/- 0.26 nmol/10(9) PLTs). Mean beta-TG levels were significantly higher (P less than 0.01) in MPD patients (165.00 +/- 28.29 ng/ml) than in healthy controls (81.76 +/- 14.63 ng/ml). Mean platelet production half-time was significantly shorter in MPD (2.48 +/- 0.24 d) than in the control group (3.43 +/- 0.17 d), after adjustment for age by covariance analysis (P less than 0.005). Our data do not indicate an abnormal prostaglandin synthesis and are consistent with the hypothesis that a disseminated intravascular platelet aggregation might take place in MPD patients.     

Plasma and platelet plasminogen activator inhibitor-1 in patients with acute myocardial infarction

Several studies have demonstrated an increased level of plasma plasminogen activator inhibitor-1 (PAI-1) in patients with coronary artery disease (CAD). However, the concentration of PAI-1 in platelets, which accounts for more than 90% of the blood PAI-1, is unknown in these patients. The present study evaluated the concentrations of PAI-1 and several fibrinolytic factors in the plasma and platelets of patients with CAD and the serial changes in patients with acute myocardial infarction (AMI). All 72 subjects had coronary angiography and were divided into 3 groups: CAD(-) group without coronary artery stenosis or myocardial ischemia (n=20), CAD(+) group with either stable angina pectoris (n=18) or old myocardial infarction (n=12) with coronary artery stenosis, and the AMI group admitted within 24h of symptom onset who underwent successful percutaneous transluminal coronary angioplasty (n=22). The concentrations of plasma PAI-1, tissue plasminogen activator (t-PA), and t-PA x PAI-1 complex were similar in the CAD(-) and CAD(+) groups, but were greater on day 1 in the AMI group compared with the 2 CAD groups. There were no significant differences between the 3 groups in the plasma concentrations of thrombin antithrombin III complex (TAT), alpha2-plasmin inhibitor-plasmin complex (PIC), beta-thromboglobulin (beta-TG), and platelet factor 4 (PF-4). The platelet PAI-1 concentrations did not differ between the CAD(-) and CAD(+) groups, but was greater on day 1 in the AMI group compared to the CAD groups. The platelet beta-TG and PF-4 were similar between the 3 groups. In the AMI group, both the plasma and platelet PAI-1 concentrations were greater on day 1, but the plasma PAI-1 rapidly decreased by day 5 and remained low on day 28 compared with day 1. The platelet PAI-1 concentration gradually decreased by day 5 and was further decreased by day 28. The serial changes of the plasma t-PA and t-PA PAI-1 complex during the course of AMI were similar to those of the plasma PAI-1. A positive correlation was found between the plasma and platelet PAI-1 in all 72 patients, but not in the AMI group alone. These results suggest that the PAI-1 that has accumulated in platelets at the onset of AMI might be released in large amounts into the plasma, resulting in an increase in thrombus formation.