Primary haemostasis: sticky fingers cement the relationship.
Platelet aggregation to form a haemostatic plug, or thrombus, plays a key role in preventing bleeding from a wound. Recent studies have provided new insights into how platelet receptors are deployed during the interactions with the vascular subendothelial matrix that lead to haemostatic plug formation. (+info)
Socioeconomic status and determinants of hemostatic function in healthy women.
Hemostatic factors are reported to be associated with coronary heart disease (CHD). Socioeconomic status (SES) is 1 of the determinants of the hemostatic profile, but the factors underlying this association are not well known. Our aim was to examine determinants of the socioeconomic differences in hemostatic profile. Between 1991 and 1994, we studied 300 healthy women, aged 30 to 65 years, who were representative of women living in the greater Stockholm area. Fibrinogen, factor VII mass concentration (FVII:Ag), activated factor VII (FVIIa), von Willebrand factor (vWF), and plasminogen activator inhibitor-1 (PAI-1) were measured. Educational attainment was used as a measure of SES. Low educational level and an unfavorable hemostatic profile were both associated with older age, unhealthful life style, psychosocial stress, atherogenic biochemical factors, and hypertension. Levels of hemostatic factors increased with lower educational attainment. Independently of age, the differences between the lowest (mandatory) and highest (college/university) education in FVII:Ag levels were 41 microg/L (95% confidence interval [CI], 15 to 66 microg/L, P=0.001), 0.26 g/L (95% CI, 0.10 to 0.42 g/L, P=0.001) in fibrinogen levels, and 0.11 U/mL (95% CI, 0.09 to 0.12 U/mL, P=0.03) in levels of vWF. The corresponding differences in FVIIa and PAI-1 were not statistically significant. With further adjustment for menopausal status, family history of CHD, marital status, psychosocial stress, lifestyle patterns, biochemical factors, and hypertension, statistically significant differences between mandatory and college/university education were observed in FVII:Ag (difference=34 microg/L; 95% CI, 2 to 65 microg/L, P=0.05) but not in fibrinogen (difference=0.03 g/L; 95% CI, -0.13 to 0.19 g/L, P=0.92) or in vWF (difference=0.06 U/mL; 95% CI, -0.10 to 0.22 U/mL, P=0.45). An educational gradient was most consistent and statistically significant for FVII:Ag, fibrinogen, and vWF. Age, psychosocial stress, unhealthful life style, atherogenic biochemical factors, and hypertension mediated the association of low educational level with elevated levels of fibrinogen and vWF. Psychosocial stress and unhealthful life style were the most important contributing factors. There was an independent association between education and FVII:Ag, which could not be explained by any of these factors. (+info)
Alpha2-antiplasmin gene deficiency in mice is associated with enhanced fibrinolytic potential without overt bleeding.
alpha2-antiplasmin (alpha2-AP) is the main physiologic plasmin inhibitor in mammalian plasma. Inactivation of the murine alpha2-AP gene was achieved by replacing, through homologous recombination in embryonic stem cells, a 7-kb genomic sequence encoding the entire murine protein (exon 2 through part of exon 10, including the stop codon) with the neomycin resistance expression cassette. Germline transmission of the mutated allele was confirmed by Southern blot analysis. Mendelian inheritance of the inactivated alpha2-AP allele was observed, and homozygous deficient (alpha2-AP-/-) mice displayed normal fertility, viability, and development. Reverse transcription-polymerase chain reaction confirmed the absence of alpha2-AP mRNA in kidney and liver from alpha2-AP-/- mice, in contrast to wild-type (alpha2-AP+/+) mice. Immunologic and functional alpha2-AP levels were undetectable in plasma of alpha2-AP-/- mice, and were about half of wild-type in heterozygous littermates (alpha2-AP+/-). Other hemostasis parameters, including plasminogen activator inhibitor-1, plasminogen, fibrinogen, hemoglobin, hematocrit, and blood cell counts were comparable for alpha2-AP+/+, alpha2-AP+/-, and alpha2-AP-/- mice. After amputation of tail or toe tips, bleeding stopped spontaneously in alpha2-AP+/+, as well as in alpha2-AP+/- and alpha2-AP-/- mice. Spontaneous lysis after 4 hours of intravenously injected 125I-fibrin-labeled plasma clots was significantly higher in alpha2-AP-/- than in alpha2-AP+/+ mice when injecting clots prepared from alpha2-AP+/+ plasma (78% +/- 5% v 46% +/- 9%; mean +/- SEM, n = 6 to 7; P =.02) or from alpha2-AP-/- plasma (81% +/- 5% v 46% +/- 5%; mean +/- SEM, n = 5; P =.008). Four to 8 hours after endotoxin injection, fibrin deposition in the kidneys was significantly reduced in alpha2-AP-/- mice, as compared with alpha2-AP+/+ mice (P +info)
Thrombelastographic changes and early rebleeding in cirrhotic patients with variceal bleeding.
BACKGROUND: Routine coagulation tests do not necessarily reflect haemostasis in vivo in cirrhotic patients, particularly those who have bleeding varices. Thrombelastography (TEG) can provide a global assessment of haemostatic function from initial clot formation to clot dissolution. AIM: To evaluate TEG changes in cirrhotic patients with variceal bleeding and their association with early rebleeding. PATIENTS/METHODS: Twenty cirrhotic patients with active variceal bleeding had serial TEG and routine coagulation tests daily for seven days. The TEG variables before the day of rebleeding (n = 6) were compared with those of patients without rebleeding (n = 14). RESULTS: Baseline characteristics of the rebleeding and non-rebleeding groups were comparable apart from a higher incidence of uncontrolled infection on the day of rebleeding in the rebleeding group (p = 0.007). The patients in the rebleeding group were more hypocoagulable before the day of rebleeding as shown by longer r (42 v 24 mm, p < 0.001) and k (48 v 13 mm, p < 0.001) and smaller a (12 v 38 degrees, p < 0.001) compared with the mean of daily results of the non-rebleeding group. Routine coagulation tests, however, showed no significant differences between the two groups. CONCLUSION: The results of serial TEG measurements suggest that hypocoagulability may be associated with early rebleeding in cirrhotic patients. (+info)
Pravastatin therapy in hyperlipidemia: effects on thrombus formation and the systemic hemostatic profile.
OBJECTIVES: The study sought to determine the effects of lipid-lowering with pravastatin on the systemic fibrinolytic profile and on thrombus formation under dynamic flow conditions. BACKGROUND: Lowering cholesterol (C) decreases clinical events in coronary artery disease (CAD) patients, but an analysis of the effects of lipid-lowering on the entire hemostatic and thrombotic profile has not been conducted. METHODS: We prospectively studied 93 stable patients with untreated low-density lipoprotein cholesterol (LDL-C) >145 mg/dl. The CAD patients received pravastatin, and non-CAD patients were randomized to pravastatin versus placebo (double-blind). Thrombus formation upon an injured vascular surface was assessed in a substudy of 40 patients with a previously validated ex vivo perfusion chamber system. Systemic hemostatic markers and thrombus formation were evaluated at baseline, three and six months. RESULTS: Placebo produced no changes in either the lipid profile, any of the hemostatic markers, or the ex vivo thrombus formation. Both pravastatin groups (CAD and non-CAD) showed decreased LDL-C by 30% within 6 weeks (188 to 126 mg/dl, p < 0.001 vs. baseline), and decreased plasminogen activator inhibitor-1 at 3- and 6-month follow-up compared to baseline (15% to 18% decrease at 3 months and 21% to 23% at 6 months). For the tissue plasminogen activator antigen, CAD and non-CAD groups showed significant decreases at 6 months compared to baseline (10% and 13%, respectively). No significant changes were observed with treatment in d-dimer, fibrinopeptide A, prothrombin fragment F1.2, factor VIIa, von Willebrand factor, or C-reactive protein. Fibrinogen levels were significantly increased at 6 months compared to baseline, though still below the upper normal limit. In the perfusion chamber substudy, there was a decrease in thrombus area in non-CAD patients treated with pravastatin at both 3 and 6 months compared to baseline (by 21% and 34%, respectively). The CAD patients showed decreases in thrombus formation by 13% at 3 months, and by 16% at 6 months. The change in LDL-C- correlated modestly with the change in thrombus formation (r = 0.49; p < 0.01). CONCLUSIONS: Pravastatin therapy significantly decreased thrombus formation and improved the fibrinolytic profile in patients with and without CAD. These early effects may, in part, explain the benefit rendered in primary and secondary prevention of CAD. (+info)
Neutrophil activation and hemostatic changes in healthy donors receiving granulocyte colony-stimulating factor.
Granulocyte colony-stimulating factor (G-CSF) enhances neutrophil functions in vitro and in vivo. It is known that neutrophil-derived products can alter the hemostatic balance. To understand whether polymorphonuclear leukocyte (PMN) activation, measured as PMN degranulation and phenotypical change, may be associated to hemostatic alterations in vivo, we have studied the effect of recombinant human G-CSF (rHuG-CSF) administration on leukocyte parameters and hemostatic variables in healthy donors of hematopoietic progenitor cells (HPCs). Twenty-six consecutive healthy donors receiving 10 micrograms/kg/d rHuG-CSF subcutaneously for 5 to 7 days to mobilize HPCs for allogeneic transplants were included in the study. All of them responded to rHuG-CSF with a significant white blood cell count increase. Blood samples were drawn before therapy on days 2 and 5 and 1 week after stopping rHuG-CSF treatment. The following parameters were evaluated: (1) PMN activation parameters, ie, surface CD11b/CD18 antigen expression, plasma elastase antigen levels and cellular elastase activity; (2) plasma markers of endothelium activation, ie, thrombomodulin (TM) and von Willebrand factor (vWF) antigens; (3) plasma markers of blood coagulation activation, ie, F1+2, TAT complex, D-dimer; and (4) mononuclear cell (MNC) procoagulant activity (PCA) expression. The results show that, after starting rHuG-CSF, an in vivo PMN activation occurred, as demonstrated by the significant increment of surface CD11b/CD18 and plasma elastase antigen levels. Moreover, PMN cellular elastase activity, which was significantly increased at 1 day of treatment, returned to baseline at day 5 to 6, in correspondence with the elastase antigen peak in the circulation. This change was accompanied by a parallel significant increase in plasma levels of the two endothelial and the three coagulation markers. The PCA generated in vitro by unstimulated MNC isolated from rHuG-CSF-treated subjects was not different from that of control cells from untreated subjects. However, endotoxin-stimulated MNC isolated from on-treatment individuals produced significantly more PCA compared with both baseline and control samples. All of the parameters were decreased or normal 1 week after stopping treatment. These data show that rHuG-CSF induces PMN activation and transiently affects some hemostatic variables in healthy HPC donor subjects. The clinical significance of these findings remains to be established. (+info)
Hormone replacement therapy, inflammation, and hemostasis in elderly women.
Lipid-lowering by postmenopausal hormone therapy (HRT) explains only partly the assumed coronary risk reduction associated with therapy. To explore other possible mechanisms, we studied associations of HRT use with inflammation and hemostasis risk markers in women >/=65 years of age. Subjects were selected from 3393 participants in the fourth year examination of the Cardiovascular Health Study, an observational study of vascular disease risk factors. After excluding women with vascular disease, we compared levels of inflammation and hemostasis variables in the 230 women using unopposed estrogen and 60 using estrogen/progestin, with those of 196 nonusers selected as controls. Compared with nonusers, unopposed estrogen use was associated with 59% higher mean C-reactive protein (P<0.001), but with modestly lower levels of other inflammation indicators, fibrinogen, and alpha-1 acid glycoprotein (P<0.001). Factor VIIc was 16% higher among estrogen users (P<0.001), but this was not associated with higher thrombin production (prothrombin fragment 1-2), or increased fibrin breakdown (D-dimer). Concentration of plasminogen activator inhibitor-1 was 50% lower in both using groups (P<0.001) compared with nonusers, and this was associated with higher plasmin-antiplasmin complex: 8% higher in estrogen and 18% higher in estrogen/progestin users (P<0. 05). Relationships between the markers and hormone use were less pronounced in estrogen/progestin users, with no association for C-reactive protein except in women in upper 2 tertiles of body mass index (P for interaction, 0.02). The direction and strength of the associations of HRT use with inflammation markers differed depending on the protein, so it is not clear whether HRT confers coronary risk reduction through an inflammation-sensitive mechanism. Associations with hemostasis markers indicated no association with evidence of procoagulation and a possible association with increased fibrinolytic activity. (+info)
Strategy for balancing anticoagulation and hemostasis in aortocoronary bypass surgery: blood conservation and graft patency.
The minimal effective dose of aprotinin on hemostasis under normothermic perfusion, the influence of anticoagulant therapy on graft patency, and the thromboembolic and hemorrhagic events were investigated after aortocoronary bypass graft operation (CABG). One hundred CABG patients under normothermic perfusion were randomly divided into the following groups: (1) coumadin plus acetylsalicylic acid (ASA) (n=32); no aprotinin used during cardiopulmonary bypass (CPB); (2) minimal-dose, 10(6) KIU during CPB, aprotinin used, followed by ASA and coumadin (n=36); and (3) very low-dose, total of 2x10(6) KIU before CPB and during CPB; aprotinin used; anticoagulation therapy with heparin early after surgery and followed by replacement with ASA and coumadin (n=32). The patency of arterial grafts was 100% in all groups. The patency of vein grafts was 95-98% and there was no difference among the groups. The blood loss was significantly reduced in both aprotinin groups (groups 2 and 3) compared to the coumadin plus ASA group, although no difference existed between the 2 aprotinin groups. Postoperative thrombotic and hemorrhagic events were not observed in any group. From this study, it was concluded that 10(6) KIU aprotinin in pump-prime-only followed by oral ASA and coumadin was the recommendation from the benefit/cost consideration. (+info)