Plasma beta-thromboglobulin in severe infection

The plasma concentration of beta-thromboglobulin was serially measured in nine patients with septicemia, ten patients with pneumonia and five thrombo- and granulocytopenic patients with acute leukemia. Six patients with septicemia out of the eight studied on days 1-3 and all eight patients studied 7-14 days after onset had an abnormal high beta-thromboglobulin level. One patient with pneumonia out of six studied on days 1-3 and six out of nine studied on 7-14 days after onset had an abnormal high value. A rising trend in plasma beta-thromboglobulin with the highest mean levels at one to two weeks after onset was common to both groups. Positive ethanol gelation, increased level of fibrin/fibrinogen degradation products, decreased antithrombin III, increased FVIII complex and disproportionate ratio of FVIII:C to FVIIIR:Ag were common in both groups in the early stages of the disease. All the five patients with leukemia had a lower than normal beta-thromboglobulin level throughout the study but showed in the coagulation parameters changes similar to those observed in the other groups. Judging from the commonness of abnormal beta-thromboglobulin values in the two first patient groups, low grade platelet activation is a normal response in severe infection.     

Contribution of platelets to increased plasminogen activator inhibitor type 1 in severe preeclampsia

Plasminogen activator inhibitor activity and antigen were evaluated in plasma, serum and platelet lysate in patients with severe preeclampsia (n = 12), and in normal pregnant women (n = 21). Other parameters, including beta-thromboglobulin and platelet count, were also evaluated. A significant increase (p less than 0.05) in beta-thromboglobulin was observed in platelet poor plasma of preeclamptic women when compared with that of normal pregnant women, and the platelet count was lower in the preeclamptic group than in the normal pregnant group. A significant increase in plasminogen activator inhibitor activity and antigen was observed in platelet poor plasma of the preeclamptic group as compared with normal pregnant women, whereas platelet lysate from preeclamptic women showed a significant decrease in both plasminogen activator inhibitor activity and antigen as compared with that of normal pregnant women. No correlation between beta-thromboglobulin and plasminogen activator inhibitor type 1 antigen in platelet poor plasma was observed, but a significant inverse correlation (r = -0.78, p less than 0.05) between beta-thromboglobulin in platelet poor plasma and plasminogen activator inhibitor-1 antigen in platelet lysate was obtained in preeclamptic patients. However, in platelet poor plasmas obtained from normal platelet rich plasmas activated with thrombin (0.1 IU/ml, 37 degrees C, 1 min), an increase of about 300 ng/ml in beta-thromboglobulin was observed while the increase in plasminogen activator inhibitor was only 4 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)     

Are haemostatic and fibrinolytic parameters predictors of preeclampsia in pregnancy-associated hypertension?

The plasma levels of several haemostatic and fibrinolytic parameters were measured before and after delivery in 61 hypertensive pregnant women of whom 22 developed preeclampsia, and compared to the results obtained in 42 normal pregnant women. In the two last weeks before delivery (D less than or equal to -15) tPA antigen, PAI-1 activity, vWF:Ag/FVIII:C ratio, ATIII activity and platelet count were found to be significantly different in the hypertensive pregnant women with and without preeclampsia. Combined all together, an association of three of these five parameters were found to be pathological (i.e.:tPA:Ag greater than or equal to 19 ng/ml, PAI-1 activity greater than or equal to 58 IU/ml, vWF:Ag/FVIII:C ratio greater than or equal to 2.6, ATIII activity less than or equal to 73%) in none of the hypertensive women without preeclampsia and in only 35% of the preeclamptic group. A positive correlation was demonstrated between vWF:Ag/FVIII:C ratio and tPA:antigen levels suggesting that both tPA and vWF:Ag could be considered as early indicators of a possible micro angiopathy occurring in preeclampsia. However, due to the high dispersion of the results, it appears that the investigated haemostatic and/or fibrinolytic criteria give only presumptive arguments before assigning risk for preeclampsia development among hypertensive pregnant women.     

Evaluation of platelet function in pregnancy. Comparative studies in non-smokers and smokers

We have evaluated the possible role of platelet functional abnormalities as a contributory cause of thrombosis during pregnancy and to the increased fetal mortality and morbidity among women who smoke. Fifty-three pregnant women were enrolled and evaluated on two separate prenatal visits held between the 20th and 36th week of pregnancy and, when possible, post partum. Smoking status was evaluated by personal statement and alveolar carbon monoxide levels. Women in the smoking group deliberately avoided cigarettes for at least 20 minutes before sampling. Plasma levels of beta-thromboglobulin, thromboxane B2, and 6-Keto PGF1 alpha were evaluated. A significant increase in 6-Keto PGF1 alpha was noted among smoking women as pregnancy advanced. 6-Keto PGF1 alpha levels decreased among non-smoking women while beta-thromboglobulin increased significantly between the 20th and 33rd week of pregnancy in non-smokers. Platelet aggregation, both in platelet rich plasma and in whole blood (by impedance aggregometry), was evaluated by five different parameters and four different aggregating agents. Significant differences between the non-smoking and smoking pregnant women were noted for selected age cohorts and aggregating agents. An increase in platelet reactivity among smokers was observed in whole blood by impedance aggregometry with adenosine diphosphate and in two age cohorts using platelet rich plasma. In two groups in which aggregation was significantly accelerated among non-smokers, epinephrine was used as the aggregating agent.     

Studies on the haemostatic system in peripheral arterial disease 2. Variations in factor VIII components (FVIII:C ; FVIIIR:Ag ; FVIII:WF) before and after venous occlusion

Factor VIII coagulant activity (FVIII:C), ristocetin co-factor or Willebrand Factor activity (FVIII:WF) and antigen related to FVIII (FVIIIR:Ag) were measured in a group of patients with peripheral arterial disease (PAD) and in a comparable control group. No differences were recorded between patients and controls both in basal conditions and after a standardized venous occlusion (VO) test. VO induced a significant increase in all the FVIII components, comparable in the two groups, with only minor variations in the ratios between them, due to a relatively greater response of the two activities with regard to the protein (FVIIIR:Ag) concentration. FVIII:C was significantly correlated with FVIIIR:Ag and with FVIII:WF only in controls in basal conditions, while no correlation was found in PAD group, nor after VO in either group.

Patients with atherosclerosis obliterans seem therefore to have normal levels of FVIII components and to mantain a normal capacity of responding to VO stimulation. FVIII coagulant activity can be acquired in local blood, or, in alternative, FVIII complex can be released as a whole from vascular walls following venous stasis.     

Shortening of bleeding time by 1-deamino-8-arginine vasopressin (DDAVP) in the absence of platelet von Willebrand factor in Gray platelet syndrome

The Gray platelet syndrome is a rare disorder characterised by the absence of platelet alpha-granules and their contents. We describe a new patient and the effects of infusions of 1-deamino-8-arginine vasopressin (DDAVP). The patient had a prolonged skin bleeding time and his platelets had reduced numbers of alpha-granules, increased vacuolation and reduced retention on glass beads. Platelet von Willebrand factor antigen (vWf:Ag) was undetectable and levels of platelet fibrinogen, beta-thromboglobulin, platelet factor 4 and thrombospondin were reduced. All tests of plasma coagulation factors were normal, including Factor VIII (F.VIII:C), vWf:Ag, ristocetin cofactor (R:CoF) and botrocetin cofactor. Platelet ATP, ADP, platelet albumin, surface membrane glycoproteins and 14C-serotonin uptake were also normal. Infusions of DDAVP increased plasma F.VIII:C, vWf:Ag and R:CoF and shortened the bleeding time on two occasions. This suggests that DDAVP shortens the bleeding time by releasing vWf:Ag and/or other proteins from cellular storage sites other than the platelet.     

Studies on the pathophysiology and treatment of von Willebrand's disease. VI. Variant von Willebrand's disease complicating placenta previa

The clinical course of a pregnant patient with a variant form of von Willebrand's disease (type IIA) who was complicated with placenta previa totalis, breech presentation and premature delivery is described. Following whole blood transfusion, she underwent a cesarean section without postoperative hemorrhagic complications. Factor VIII/von Willebrand factor (FVIII/vWF)-related activities (factor VIII procoagulant activity [VIII:C], factor VIII-related antigen [VIIIR:Ag] and ristocetin cofactor [VIIIR:RCo]), Duke bleeding time and platelet retention to glass beads were monitored during pregnancy, labor and puerperium. Gradual increase in FVIII/vWF-related activities and shortening of bleeding time were found during her gestation. Platelet retention, however, remained low. Qualitative analysis of plasma FVIII/vWF with crossed immunoelectrophoresis and gel filtration on Sepharose 2B demonstrated that the large forms of FVIII/vWF, which is important for primary hemostasis, did not appear in the blood during gestation. Therefore, patients with type IIA von Willebrand's disease seem to be more susceptible to bleeding complications at delivery.     

Hormonal control of haemostasis during hypoglycaemia in diabetes mellitus

Factor VIII (FVIII) and plasminogen activator activity (PAA) rise during hypoglycaemia, and this might contribute to the vascular complications of diabetes. Similar changes in haemostasis accompany raised plasma levels of vasopressin (aVP) and adrenaline. To investigate the effects of these hormones on haemostasis during hypoglycaemia and the role of plasma insulin concentrations, eight insulin-dependent diabetic patients underwent controlled hypoglycaemia for 20 min and 13 diabetic patients were investigated during hyperinsulinaemia with blood glucose maintained at 8.0 mmol/l. During hypoglycaemia, insulin levels increased to median values of 114 mU/l, a VP rose from 0.5 to 4.4 (p less than 0.005) pg/ml and adrenaline from 0.4 to 4.4 nmol/l (p less than 0.005). FVIII coagulant activity (FVIII:C) rose from 0.75 to 1.09 IU/ml (p less than 0.01) and the ristocetin co-factor (FVIIIR:Co) and von Willebrand factor antigen (vWF:Ag) showed similar responses. PAA increased from 156 to 745 units (p less than 0.005). During hyperinsulinaemia, insulin rose following infusion from 24 to 52 and 118 mU/l, maintained for an hour at each level. Despite this, plasma aVP, FVIII:C, FVIIIR:Co, vWF:Ag and PAA remained unchanged. This study indicates that the marked changes in FVIII, vWF and PAA concentrations which accompany hypoglycaemia depend on low blood glucose and not raised plasma insulin. The response in probably mediated by increases in adrenaline and aVP, which are part of the physiological response to hypoglycaemia.     

Effects of BM 13.177, a new antiplatelet drug in patients with atherosclerotic disease

Seven males with atherosclerotic disease received daily 1.6 g of the thromboxane antagonist BM 13.177 in two separate oral dosages over a period of four days. The drug significantly reduced elevated plasma levels of thromboxane B2, beta-thromboglobulin and platelet factor 4, whereas thromboxane B2 generation was only slightly depressed. BM 13.177 inhibited platelet aggregation by collagen, and to a minor degree the second wave of ADP induced aggregation. Platelet sensitivity to prostacyclin and aggregation by ristocetin were not altered. Bleeding time was prolonged. All effects disappeared within 24 hours after the last application of the drug. No side effects were noted. Thus BM 13.177 appears to be a safe and effective new antiplatelet drug.     

Cerebrovascular acetazolamide reactivity and platelet function in asymptomatic cerebral thrombosis.

In order to find out the relationship between the cerebrovascular acetazolamide reactivity and platelet function in asymptomatic cerebral thrombosis, 10 cases of asymptomatic cerebral infarction and 10 age-matched control subjects were studied. The cerebrovascular acetazolamide reactivity was measured using xenon computed tomography method. As markers of platelet function, the plasma concentrations of platelet factor 4, beta-thromboglobulin, thromboxane B2, and 11-dehydrothromboxane B2 were determined. The cerebrovascular acetazolamide reactivity was significantly lower in the asymptomatic cerebral infarction group than in the control group. The plasma concentrations of platelet factor 4, beta-thromboglobulin, thromboxane B2, and 11-dehydrothromboxane B2 were higher in the asymptomatic cerebral infarction group than in the control group. There was a significant negative correlation between the cerebrovascular acetazolamide reactivity and the plasma concentrations of platelet factor 4, beta-thromboglobulin, thromboxane B2, and 11-dehydrothromboxane B2. The low cerebrovascular acetazolamide reactivity is considered to be related to platelet activation in asymptomatic cerebral thrombosis.     

Early detection of preeclampsia by determination of platelet aggregability

Preeclampsia is still a leading cause of maternal and fetal morbidity and mortality. There is evidence for the involvement of platelets. Therefore, we investigated the suitability of corrected whole blood impedance aggregometry as an early predictor of preeclampsia in 71 consecutive, high-risk pregnancies. According to the occurrence of preeclampsia, defined postpartum by an independent investigator, and the stage of pregnancy (early and late, cutoff: 25 weeks of gestation), four study groups were defined. Platelet aggregation data were corrected for the influence of hematocrit and platelet count by a special purpose software package. Women developing preeclampsia showed significantly higher platelet aggregation response compared to controls in early and late pregnancy. In early pregnancy, all women developing preeclampsia had aggregation responses to collagen higher than the highest responses among the controls. Hence, this test had a 100% positive predictive value of subsequent preeclampsia. Despite being significantly increased, platelet aggregability was of minor predictive value in late pregnancy. We conclude that preeclampsia is accompanied by exaggerated platelet aggregability, particularly perceptible early in the course of pregnancy. We propose collagen-induced whole blood platelet aggregation with correction for the influence of hematocrit and platelet count for early detection of preeclampsia.     

Platelet thromboxane release after subarachnoid hemorrhage and surgery

We studied adenosine diphosphate-induced platelet aggregation and the associated release of thromboxane B2 in platelet-rich plasma from 88 patients with subarachnoid hemorrhage and 26 healthy controls. During the first 3 days after subarachnoid hemorrhage, the patients showed significantly decreased (p less than 0.05) platelet aggregability and thromboxane release relative to the controls, but these effects disappeared in a few days. Platelet count increased for 3 weeks after subarachnoid hemorrhage. Surgery in 67 patients was followed by significant increases in platelet aggregability (p less than 0.05) and thromboxane release (p less than 0.001). Greatest thromboxane release was found in the eight patients showing delayed (postoperative) ischemic deterioration with a permanent neurologic deficit. Although platelet hyperaggregability and increased thromboxane release were particularly prominent in these eight patients, the role of these hematologic parameters in the pathogenesis of delayed ischemic deterioration remains unclear.     

The state of platelets preserved in extracorporeal circulation with a glycoprotein IIb/IIIa inhibitor

INTRODUCTION: Temporary inhibition of platelet function during extracorporeal circulation (platelet anesthesia) can preserve platelet count. We hypothesized that platelet anesthesia with a glycoprotein IIb/IIIa inhibitor could preserve activated platelets. MATERIALS AND METHODS: Fresh human blood from donors was recirculated for 120 min in a simulated extracorporeal circuit. Heparin and FK633, a short-acting platelet glycoprotein IIb/IIIa inhibitor, were added to recirculated blood in one group (group F, n=5) whereas only heparin was used in controls (group C, n=5). Blood samples were obtained from the donors, and at 0, 5, 15, 30, 60, and 120 min of recirculation. Platelet counts, beta-thromboglobulin, thrombin-antithrombin complex, and aggregation to adenosine diphosphate were measured. Flow cytometry was performed for measurement of fibrinogen binding, platelet surface expression of P-selectin, and microparticles. RESULTS AND CONCLUSIONS: In the FK633 group, platelet counts were preserved and beta-thromboglobulin levels remained unchanged, whereas in group C, platelet counts decreased significantly and beta-thromboglobulin increased significantly from 30 and 60 min, respectively. FK633 inhibited platelet aggregation and fibrinogen binding to platelets throughout recirculation. A significant difference between groups with respect to microparticle parameters and thrombin-antithrombin complex levels was evident by 120 min. P-selectin expression increased at 0 min in both groups, and was preserved significantly at 5 min and reduced at 120 min in group F. Platelet counts were preserved by platelet anesthesia during recirculation without platelet activation. These results suggest that FK633 inhibits the amplification loop by reducing the binding of fibrinogen to glycoprotein IIb/IIIa and platelet aggregation.     

Immediate effects of heparin and LMW heparin on some platelet and endothelial derived factors

Heparin and a low molecular heparin fragment, injected intravenously in volunteers, increased the plasma concentrations of platelet factor 4, but did not induce platelet activation as judged from excretion of 2,3-dinor-TxB2 (a major thromboxane A2 metabolite) and beta-thromboglobulin (btg) in urine and from btg levels in plasma. Heparin prolonged, within the normal range, the bleeding time in all six subjects. Platelet aggregation in platelet rich plasma was potentiated by both heparins, but platelet number, mean platelet volume and platelet distribution width were not affected. No evidence for endothelial release of prostacyclin was obtained as judged from urinary excretion of 2,3-dinor-6-keto-PGF1 alpha (a major prostacyclin metabolite), and plasma concentrations of tissue plasminogen activator, its inhibitor (PAI-1) and the von Willebrand-factor were unchanged.     

Platelet and coagulation function in patients with abnormal cardiac valves treated with sulphinpyrazone

Eight patients on warfarin with rheumatic heart disease and prosthetic cardiac valves were selected for study on the basis of persistently elevated plasma beta-thromboglobulin (beta-tg) and platelet factor 4 (PF4) concentrations. Platelet mean lifespan and fibrinogen half life were short, and positively correlated, and both were inversely related to the plasma concentration of the platelet specific proteins. Antithrombin III (ATIII) levels were also reduced. Treatment with sulphinpyrazone resulted in lengthening of both platelet and fibrinogen survival, a rise in ATIII but no change in the beta tg or PF4 concentrations. It is concluded that patients with abnormal cardiac valves and raised plasma levels of beta tg or PF4 have, despite warfarin, a consumption coagulopathy that can be inhibited by sulphinpyrazone.     

Thrombin generation in severe haemophilia A and B: the endogenous thrombin potential in platelet-rich plasma

Thrombin generation was investigated in platelet-rich plasma (PRP) from 11 healthy controls, 17 patients with severe haemophilia A and 7 patients with severe haemophilia B. Mean endogenous thrombin potential (ETP) in arbitrary fluorescence units (FU) was 226.9 +/- 44.6, 186.4 +/- 22.5, 154.2 +/- 41.3 in controls, haemophilia A and B, respectively, all at a platelet count of 200 x 10(9)/l (p = 0.004 for controls vs. haemophilia A, p = 0.003 for controls vs. haemophilia B, no significant difference between haemophilia A and B). The contribution of FVIII to thrombin generation in haemophilia A was 1.31 +/- 0.16 FU/% of FVIII:C activity, while for FIX in haemophilia B this was 0.80 +/- 0.21 FU/% of FIX activity. There was an almost linear relationship between increasing platelet count and thrombin generation up to a mean platelet count of 100 x 10(9)/l. Further increase in platelet count has only a marginal influence on thrombin generation. Platelets increase ETP in haemophilia A by 0.184 +/- 0.022 FU/10(9) platelets/l and in haemophilia B by 0.319 +/- 0.085 FU/10(9) platelets/l, and this was significantly different between the two groups (p = 0.0002). This influence of plate-lets diminishes with increasing concentration of either FVIII or FIX. In conclusion, there is a difference in thrombin generation between haemophilia A and B, and this may be attributed to the role of platelets in the assembly of the tenase complex on their surface.     

Immunohistochemistry of vascular lesion in thrombotic thrombocytopenic purpura, with special reference to factor VIII related antigen

We collected 23 autopsied cases of thrombotic thrombocytopenic purpura (TTP) and examined them immunohistochemically and electronmicroscopically to elucidate the nature of thrombi and subendothelial deposits. The findings were compared with those of 10 cases of disseminated intravascular coagulation (DIC) and 3 cases of polyarteritis nodosa (PN). Intravascular thrombi and subendothelial hyaline deposits in TTP stained weakly for fibrinogen/fibrin by the PAP technique, while they stained strongly for factor VIII related antigen (FVIIIR: Ag). Electronmicroscopically, thrombi in TTP were composed of numerous, variably degranulated and altered platelets, and a small amount of amorphous materials. Thrombi in DIC were strongly positive for fibrinogen/fibrin, while they were weakly positive for FVIIIR:Ag. Electronmicroscopically they were composed of polymerized fibrin. Fibrinoid necrotic lesions in PN were strongly positive for fibrinogen/fibrin but negative for FVIII R:Ag. Based on these findings, we concluded that thrombi in TTP are essentially platelet thrombi and that subendothelial hyaline deposits may not be a result of increased vascular permeability but may be platelet thrombi incorporated into the arterial wall and covered with newly formed endothelial cells.     

Role of platelet function in symptomatic cerebral vasospasm following aneurysmal subarachnoid hemorrhage.

To evaluate the role of platelet function in the pathogenesis of cerebral vasospasm, we compared sequential changes of platelet aggregability and beta-thromboglobulin and thromboxane B2 concentrations in blood samples from the internal jugular and peripheral vein of 13 patients with aneurysmal subarachnoid hemorrhage. Platelet function in blood from the internal jugular vein tended to be enhanced during days 0-1 but recovered to the normal range during days 2-4. After day 5, platelet function showed various patterns depending on the presence of symptomatic vasospasm. In patients without symptomatic vasospasm, sequential changes were relatively minor, with normal or slightly high values. Patients with symptomatic vasospasm already showed high platelet aggregability during the early stage of vasospasm. The concentration of beta-thromboglobulin increased several days after the onset of vasospasm, reaching 80 ng/ml or more in patients with a poor prognosis. Two of the five patients with symptomatic vasospasm showed markedly high concentrations of thromboxane B2 after day 8. These results suggest that vasospasm activates platelets and promotes aggregability and that the resulting increased tendency for thrombus formation may affect the patient's prognosis during the advanced stage.     

Acute postprandial lipaemia does not influence the activity of human platelets

Platelet function and serum lipid studies were conducted on nine healthy male subjects before and two hours after three separate meals, two of which were rich in fat: saturated fat (SF) or polyunsaturated fat (PUF), and a third control meal which contained no fat. Platelet activity was assessed by determination of in vivo platelet aggregate formation, and plasma levels of the platelet specific proteins platelet factor 4 (PF4) and beta-thromboglobulin (beta-TG). Serum triglyceride levels increased significantly after both fat containing meals but were unaffected by the fat free meal. Serum cholesterol levels were not affected by any of the three meals. Platelet function tests could not detect any alteration of in vivo platelet activity in terms of platelet aggregate formation or plasma concentrations of PF4 and beta-TG. These results are at variance with previously published studies that used less specific assays of platelet activity and which suggested platelet activation shortly after meals rich in SF.     

Prophylactic antithrombin III administration during pregnancy immediately reduces the thrombin hyperactivity of congenital antithrombin III deficiency by forming thrombin-antithrombin III complexes.

We examined the changes of haemostatic molecular markers after antithrombin III (AT III) administration in a 22-year-old woman with congenital AT III deficiency in the third trimester of pregnancy who did not have thrombosis. Various markers including fibrinopeptide A (FPA), thrombin-antithrombin III complex (TAT), prothrombin fragment F1 + 2 (F1 + 2), plasmin-alpha 2antiplasmin, D-dimer, beta-thromboglobulin, and platelet factor 4 were measured before and just after 3,000 U of AT III concentrate, which was given three times per week from the 34 week of pregnancy until delivery. Just after AT III administration, F1 + 2 and FPA levels decreased on most occasions, while TAT sometimes increased. Plasma FPA levels were markedly decreased on all 8 occasions when the plasma FPA levels was above 2.0 ng/ml before AT III administration. Plasma FPA levels were always greater than or equal to 6.4 ng/ml before AT III administration on the 4 occasions when TAT increased to above 115%. The changes of plasma F1 + 2 levels were significantly correlated with the AT III level. These results suggest that prophylactic AT III administration in the third trimester immediately inactivates intravascular thrombin to form TAT and reduce the plasma FPA level. Thus, the transient TAT elevation following AT III administration may not only be due to extraction of thrombin from the fibrin clots of thrombi but also to intravascular thrombin which is not attached to thrombi. FPA is the best molecular marker for thrombin hyperactivity and it should be monitored in AT III-deficient pregnant women in the third trimester.