Endothelial haemostatic factors are associated with progression of urinary albumin excretion in clinically healthy subjects: a 4-year prospective study.
(17/1215)
A slightly elevated urinary albumin excretion rate (UAER), above 5-10 microgram/min, is a predictor of atherosclerotic cardiovascular disease. Endothelial dysfunction is an important early feature of atherosclerosis. The plasma concentration of von Willebrand factor (vWF), a potential marker of endothelial dysfunction, predicts a subsequent increase of UAER in patients with diabetes. The aim of this study is to test the hypothesis that high concentrations of vWF as well as other haemostatic factors predict progression of UAER in clinically healthy subjects. UAER was measured together with selected markers of haemostatic function-vWF, tissue plasminogen activator (tPA), plasminogen activator inhibitor, factor VII and fibrinogen-in healthy volunteers aged 40-65 years. After a mean follow-up of 4.1 years, 64 of 74 agreed to a re-examination including re-measurement of UAER. Baseline vWF and tPA were both positively correlated to the change in UAER during follow-up (r=0.26, P=0.04 and r=0.40, P=0.001 respectively). The mean UAER increased significantly by 7.6 microgram/min and 7.5 microgram/min respectively in subjects with vWF and tPA above the medians at baseline (P=0.01 and P=0.003 respectively), whereas no changes in UAER were seen in subjects with vWF and tPA below the medians. Subjects with high tPA were also characterized by an excess of other cardiovascular risk factors at baseline. No significant differences in these risk factors were present between subjects with high or low vWF. High plasma concentrations of vWF and tPA are associated with progression of UAER in clinically healthy subjects. Both vWF and tPA are secreted by endothelial cells and the results suggest that endothelial dysfunction leads to progression of UAER. (+info)
A prospective study of G-CSF effects on hemostasis in allogeneic blood stem cell donors.
(18/1215)
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. (+info)
Haemostatic and metabolic abnormalities in women with unexplained recurrent abortion.
(19/1215)
The objective of this study was to establish whether or not patients with unexplained recurrent abortion have an increased incidence of haemostatic or metabolic abnormalities. Fifty-two patients with a history of unexplained habitual abortion (two or more spontaneous abortions before 16 weeks' gestation) were tested for protein S, protein C and antithrombin (AT) III deficiency, activated protein C (aPC) resistance, hyperhomocysteinaemia and anticardiolipin antibodies (ACA). The control group consisted of 67 healthy women with a history of only uncomplicated pregnancies. Blood samples were taken for measuring protein S, protein C, AT III, ACA and activated protein C resistance and a methionine loading test was performed. Of the 46 patients tested for protein S deficiency, 8 (17.4%) were positive. Of the 43 patients tested, two (4.7%) were protein C deficient and none was AT III deficient. Of the 42 patients tested for ACA, eight (19.1%) had detectable antibodies. Of the 44 patients tested for aPC resistance, two (4.6%) were positive. Finally, 35 patients were tested for hyperhomocysteinaemia and six (17.1%) were positive. It was concluded that parous women with a history of unexplained recurrent abortion have an increased incidence of hyperhomocysteinaemia and a trend of increased incidence of ACA can be found. (+info)
Deficient platelet-derived nitric oxide and enhanced hemostasis in mice lacking the NOSIII gene.
(20/1215)
Endothelial nitric oxide synthase (eNOS) has been identified in human platelets. Although platelet-derived nitric oxide (NO) has been shown to inhibit platelet recruitment in vitro, its role in the regulation of the hemostatic response in vivo has not been characterized. To define the role of platelet-derived NO in vivo, we studied mice that lacked a functional eNOS gene (NOSIII). Surface P-selectin expression in platelets from eNOS-deficient mice was not significantly altered; however, bleeding times were markedly decreased in eNOS-deficient versus wild-type mice (77.2+/-3 versus 133.4+/-3 seconds, P<0.00005). To determine the contribution of endothelium- versus platelet-derived NO to the bleeding time, isolated platelets from either eNOS-deficient or wild-type mice were transfused into a thrombocytopenic eNOS-deficient mouse and the bleeding time was measured. The bleeding times in mice transfused with eNOS-deficient platelets were significantly decreased compared with mice transfused with wild-type platelets (Deltableeding time, -24.6+/-9.1 and -3.4+/-5.3 seconds, respectively; P<0.04). Platelet recruitment was studied by measuring serotonin release from a second recruitable population of platelets that were added to stimulated platelets at the peak of NO production. There was 40.3+/-3.7% and 52. 0+/-2.1% serotonin release for platelets added to wild-type or eNOS-deficient platelets, respectively (P<0.05). In summary, mice that lacked eNOS had markedly decreased bleeding times even after endothelial NO production was controlled. These data suggest that the lack of platelet-derived NO alters in vivo hemostatic response by increasing platelet recruitment. Thus, these data support a role for platelet-derived NO production in the regulation of hemostasis. (+info)
Tissue factor is required for uterine hemostasis and maintenance of the placental labyrinth during gestation.
(21/1215)
We employed a novel mouse line that expresses low levels of human tissue factor (TF) in the absence of murine TF to analyze the role of TF in gestation. Low-TF female mice had a 14-18% incidence of fatal postpartum uterine hemorrhage, suggesting that TF plays an important role in uterine hemostasis. Low-TF female mice mated with low-TF male mice had a 42% incidence of fatal midgestational hemorrhage (n = 41), whereas no fatal midgestational hemorrhages were observed in low-TF female mice mated with wild-type male mice (n = 43). Placentas of low-TF embryos from both low-TF and normal (+/-) TF females were abnormal and contained numerous maternal blood pools in the labyrinth. Placentas of TF null embryos surviving beyond embryonic day 10.5 exhibited similar defects. The mouse maternal-embryonic placental barrier consists of four cellular layers (layers I, II, and III and endothelial cells), where layer I lines the maternal lacunae. Comparison of TF-deficient placentas with control placentas by immunohistochemical and ultrastructural analyses revealed thinning of layer I and a reduction in the number of cellular contacts of layer I trophoblasts spanning the maternal blood space between adjacent trabeculae. These structural changes in low-TF and TF null placentas result in enlarged maternal lacunae, as determined by morphometric analysis, and placental hemorrhage, which leads to midgestational death of low-TF female mice. This study demonstrated that TF is required for uterine hemostasis and revealed an unexpected role of TF in the maintenance of the placental labyrinth. (+info)
Modulation of haemostatic function and prevention of experimental thrombosis by red wine in rats: a role for increased nitric oxide production.
(22/1215)
1. The effects of ethyl alcohol and wine (red and white) on haemostatic parameters and experimental thrombosis were studied in rats; NO was evaluated as a possible mediator of these effects. 2. We found that red wine (12% alcohol) supplementation (8.4 +/- 0.4 ml d-1 in drinking water, for 10 days) induced a marked prolongation of 'template' bleeding time (BT) (258 +/- 13 vs 132 +/- 13 s in controls; P < 0.001), a decrease in platelet adhesion to fibrillar collagen (11.6 +/- 1.0 vs 32.2 +/- 1.3%; P < 0.01) and a reduction in thrombus weight (1.45 +/- 0.33 vs 3.27 +/- 0.39 mg; P < 0.01). 3. Alcohol-free red wine showed an effect similar to red wine. In contrast, neither ethyl alcohol (12%) nor white wine (12% alcohol) affected these systems. 4. All these effects were also observed after red wine i.v. injection (1 ml kg-1 of 1:4 dilution) 15 min before the experiments. 5. The effects of red wine were prevented by the NO inhibitor, N omega nitro-L-arginine-methyl ester (L-NAME). L-arginine, not D-arginine, reversed the effect of L-NAME on red wine infusion. 6. Red wine injection induced a 3 fold increase in total radical-trapping antioxidant parameter values of rat plasma with respect to controls, while white wine and alcohol did not show any effect. 7. Our study provides evidence that red wine modulates primary haemostasis and prevents experimental thrombosis in rats, independently of its alcohol content, by a NO-mediated mechanism. (+info)
Targeted inhibition of intrinsic coagulation limits cerebral injury in stroke without increasing intracerebral hemorrhage.
(23/1215)
Agents that restore vascular patency in stroke also increase the risk of intracerebral hemorrhage (ICH). As Factor IXa is a key intermediary in the intrinsic pathway of coagulation, targeted inhibition of Factor IXa-dependent coagulation might inhibit microvascular thrombosis in stroke without impairing extrinsic hemostatic mechanisms that limit ICH. A competitive inhibitor of native Factor IXa for assembly into the intrinsic Factor X activation complex, Factor IXai, was prepared by covalent modification of the Factor IXa active site. In a modified cephalin clotting time assay, in vivo administration of Factor IXai caused a dose-dependent increase in time to clot formation (3.6-fold increase at the 300 micrograms/kg dose compared with vehicle-treated control animals, P < 0.05). Mice given Factor IXai and subjected to middle cerebral artery occlusion and reperfusion demonstrated reduced microvascular fibrin accumulation by immunoblotting and immunostaining, reduced 111In-labeled platelet deposition (42% decrease, P < 0.05), increased cerebral perfusion (2.6-fold increase in ipsilateral blood flow by laser doppler, P < 0.05), and smaller cerebral infarcts than vehicle-treated controls (70% reduction, P < 0.05) based on triphenyl tetrazolium chloride staining of serial cerebral sections. At therapeutically effective doses, Factor IXai was not associated with increased ICH, as opposed to tissue plasminogen activator (tPA) or heparin, both of which significantly increased ICH. Factor IXai was cerebroprotective even when given after the onset of stroke, indicating that microvascular thrombosis continues to evolve (and may be inhibited) even after primary occlusion of a major cerebrovascular tributary. (+info)
Magnitude and time course of impaired primary haemostasis after stopping chronic low and medium dose aspirin in healthy volunteers.
(24/1215)
Aspirin ingestion within the previous 7-10 days is often considered a relative contraindication to performing invasive procedures. However, aspirin is an important component of many patients' treatment and withholding therapy for this time may be dangerous. To measure both the magnitude of the impairment in primary haemostasis induced by aspirin and how much recovery of platelet function occurs within 48 h of stopping aspirin, we studied serial changes in bleeding time (BT) in a randomized, double-blind, placebo-controlled study. Fifty-two healthy volunteers had BT performed before and at 2, 9, 24 and 48 h after a 7-day course of either aspirin 75 mg, 300 mg or placebo. The main outcome recorded was BT at each time. Nearly 25% of subjects had extended BT to more than 10 min, but no BT were greater than 10 min, 48 h after stopping aspirin. There was a small but statistically significant (P < 0.01) difference between the 48-h and baseline BT in both aspirin groups (49 and 64 s in the 75 mg and 300 mg groups, respectively). There was no difference in the magnitude or time course of effect between low and medium dose aspirin (P = 0.392 and P = 0.797, respectively). We conclude that despite considerable inter-individual variability in the magnitude of aspirin effect on primary haemostasis, the time course of effect was consistent. In healthy volunteers, the defect in primary haemostasis had largely disappeared 48 h after the last dose. (+info)