thromboplastin and Peripheral-Vascular-Diseases

Tissue factor (TF) is the physiological initiating mechanism for blood coagulation. Platelets play an important role in monocyte TF expression, thrombosis and inflammation. Aspirin, clopidogrel and cilostazol, which inhibit platelet responses by different mechanisms, are widely used in patients with arterial diseases. We tested the hypothesis that platelet-inhibiting agents inhibit the levels of circulating TF procoagulant activity (TF-PCA) in patients with peripheral arterial disease (PAD). Twenty-six patients with lower extremity PAD, average age 65.9 +/- 8.4 years (mean +/- SEM), were studied at baseline and following sequential two-week treatment regimens with aspirin (325 mg daily), clopidogrel (75 mg daily) or a phosphodiesterase inhibitor cilostazol (100 mg twice daily) singly, and with each possible combination of these agents. Circulating TF-PCA in whole blood, and plasma factor VIIa, prothrombin fragment F1.2, thrombin-antithrombin complexes (TAT), and P-selectin were measured. Baseline TF-PCA levels in the patients were elevated (131 +/- 19 U/ml) compared to control subjects (23 +/- 2, p < 0.0001). TF-PCA levels declined following treatment with clopidogrel alone, and with combinations of clopidogrel with aspirin or cilostazol, with the lowest levels being with the triple-drug combination. Plasma P-selectin declined in all treatment groups. No changes were noted in plasma factor VIIa, F1.2 or TAT. In conclusion, treatment of PAD patients with antiplatelet agents decreases circulating TF, a molecule with prothrombotic and proinflammatory effects. These findings suggest an unrecognized mechanism, beyond inhibiting aggregation responses, for the efficacy of antiplatelet drugs in patients with arterial diseases.

Topics: Aged; Aged, 80 and over; Antithrombin III; Aspirin; Blood Platelets; C-Reactive Protein; CD40 Ligand; Cell Membrane; Cilostazol; Clopidogrel; Down-Regulation; Drug Therapy, Combination; Factor VIIa; Humans; Middle Aged; P-Selectin; Peptide Fragments; Peptide Hydrolases; Peripheral Vascular Diseases; Pilot Projects; Platelet Aggregation Inhibitors; Prospective Studies; Prothrombin; Tetrazoles; Thromboplastin; Ticlopidine

Peripheral artery disease (PAD) and intermittent claudication are common in men aged over 55 years. Once the diagnosis has been made, very few patients suffer from a deterioration of the disease. Those that do deteriorate tend to do so due to thrombosis of an affected artery. It is apparent that the disruption in the vessel wall accounts for some of the cause of the thrombosis but blood constituents also play a role. We hypothesized that levels of soluble P-selectin (sP-sel, a marker of platelet activation), von Willebrand factor (vWf, an index of endothelial damage/dysfunction), tissue factor (TF, a coagulation protein involved in the 'extrinsic' coagulation pathway) and fibrinogen would be abnormally elevated in relation to disease severity and correlated with each other, and related to ethnicity, in a multiethnic population of patients with PAD. To test this hypothesis, we studied 234 patients (80% white, 7% Indo-Asian, 13% Afro-Caribbean) with confirmed PAD [ankle brachial pressure index (ABPI)< or =0.8] and 50 healthy controls. All of the indices studied were increased in patients over controls (p<0.05). None of the indices of the hypercoagulable state were significantly different between the three ethnic groups studied. Patients with ischaemic rest pain were shown to have higher levels of plasma fibrinogen (p<0.001) although none of the other prothrombotic markers were increased in this group. Furthermore, fibrinogen was higher in cases whose ABPI was below the median (<0.52) when compared to those less severely affected, with an inverse correlation between fibrinogen and ABPI (Spearman, r=-0.178, p=0.009). In conclusion, we found a prothrombotic state in patients with PAD with increased levels of markers of endothelial damage/dysfunction, platelet activation and thrombosis, which may contribute to the pathogenesis of this condition. However, disease severity was only related to plasma fibrinogen levels.

Topics: Aged; Arteries; Arteriosclerosis; Asian People; Biomarkers; Black People; Causality; Comorbidity; Endothelium, Vascular; Female; Fibrinogen; Humans; Intermittent Claudication; Male; P-Selectin; Peripheral Vascular Diseases; Risk Assessment; Risk Factors; Severity of Illness Index; Statistics as Topic; Thromboplastin; Thrombosis; United Kingdom; von Willebrand Factor; White People

Tissue factor (TF) is one of the major initiators of coagulation and raised plasma levels have been found in various cardiovascular diseases. TF activity is, however, regulated by tissue factor pathway inhibitor (TFPI), and alteration in levels of TF and/or TFPI may thus relate to thrombogenesis and atherogenesis. To investigate possible abnormalities in TF and free TFPI (i.e. unbound to TF) and total TFPI among patients with peripheral artery disease (PAD), we studied 42 patients (mean age 57, 35 men) with objectively proven (by ABPI/Doppler) disease and 42 age- and sex- matched healthy controls. TF, free TFPI and total TFPI were measured in citrated plasma by ELISA. TF was higher in the patients with PAD compared to controls (275+/-122 pg/ml versus 158+/-60, P<0.0001) but levels of total TFPI were lower in the patients (43+/-10 ng/ml versus 50+/-15, P=0.021). There was no significant difference in levels of free TFPI between patients and controls (7.2+/-1.5 ng/ml in controls, 7.5+/-1. 6 among patients, P=0.39). Within the control patients, levels of free and total TFPI were significantly correlated (Spearman r=0.51, P=0.001) but in the patients with PAD this correlation was poor (r=0. 21, P=0.178). We suggest that reduced levels of total TFPI and raised levels of TF may contribute to the process of atherogenesis and the increased risk of thrombosis among patients with cardiovascular disease.

Topics: Adult; Aged; Cross-Sectional Studies; Enzyme-Linked Immunosorbent Assay; Female; Humans; Lipoproteins; Male; Middle Aged; Peripheral Vascular Diseases; Probability; Reference Values; Sensitivity and Specificity; Thromboplastin; Ultrasonography, Doppler; von Willebrand Factor

Thrombus formation plays a critical role in pathogenesis of cardiovascular complications in atherosclerotic peripheral arterial occlusive disease (PAOD). Tissue factor (TF) initiates the clotting cascade and is considered an important regulator of hemostasis and thrombosis. TF activity is regulated by TF pathway inhibitor (TFPI). The aim of our study was to evaluate plasma levels of the TF, TFPI and their relation to coagulation system and various other risk factors of atherosclerosis in patients with chronic limbs ischemia.. Plasma TF, total TFPI, truncated TFPI, full-length TFPI were assessed by ELISA using commercially available kits (IMUBIND Tissue Factor; Total TFPI; Truncated TFPI ELISA Kit; American Diagnostica Inc. Stamford) in 62 claudicant patients with PAOD and 20 healthy controls.. We observed statistically higher levels of TF (94+/-52 pg/mL), total TFPI (43+/-8 ng/mL), and truncated TFPI (22+/-7 ng/mL) in patients with PAOD compared to healthy individuals (TF: 66+/-15 pg/mL; total TFPI: 36+/-4 ng/mL; truncated TFPI: 14+/-5 ng/mL). Full-length TFPI (20+/-4 ng/mL) is lower in patients with PAOD than in controls (23+/-5 ng/mL). The study indicated a positive correlation between TF and truncated TFPI (r=0.34), total TFPI and full TFPI (r=0.5), total TFPI and truncated TFPI (r=0.83) in patients with PAOD, and negative correlation between full TFPI and truncated TFPI (r=-0.65) in the control.. Elevated levels of TF, disorders of balance between full-length TFPI and truncated TFPI as well as significantly increased truncated TFPI level in patients with PAOD can be independent risk factors of atherosclerotic complications.

Topics: Arterial Occlusive Diseases; Atherosclerosis; Biomarkers; Blood Coagulation; Case-Control Studies; Female; Humans; Ischemia; Lipoproteins; Lower Extremity; Male; Middle Aged; Peripheral Vascular Diseases; Pilot Projects; Risk Assessment; Risk Factors; Thromboplastin; Up-Regulation

Men and women with lower extremity peripheral arterial disease (PAD) have reduced physical activity levels compared with persons without PAD. We describe associations between physical activity levels with D-dimer, pro-coagulant factors, and inflammatory markers in patients with PAD. Participants were 188 patients with PAD identified from non-invasive vascular laboratories. Physical activity was measured over 7 days with a vertical accelerometer. We measured the ankle-brachial index (ABI) and levels of D-dimer, C-reactive protein (CRP), fibrinogen, serum amyloid A (SAA), prothrombin 1.2, t-PA antigen, PAI-1, and the t-PA antigen/PAI-1 ratio. Adjusting for age, sex, race, body mass index, ABI, comorbidities, smoking, total cholesterol/HDL ratio and statin use (for CRP only), we found significant inverse linear associations between physical activity levels and log D-dimer (p = 0.002), log CRP (p < 0.001), fibrinogen (p = 0.014), and log SAA (p = 0.012). There were no significant associations between physical activity levels and other blood factors. In an analysis adjusting for all blood factors simultaneously along with known and potential confounders, log D-dimer was the only blood factor associated significantly with physical activity levels (p = 0.036). Based on these findings, future studies should assess whether interventions to increase physical activity in patients with PAD reduce levels of D-dimer and inflammatory markers.

Topics: Arterial Occlusive Diseases; Biomarkers; C-Reactive Protein; Female; Fibrin Fibrinogen Degradation Products; Humans; Lower Extremity; Male; Middle Aged; Motor Activity; Peripheral Vascular Diseases; Thromboplastin

Increasing evidence points towards a prothrombotic state in atherosclerosis and its manifestations, such as peripheral artery disease (PAD), which is associated with thrombosis-related complications, such as acute limb ischaemia, graft thrombosis and stroke. We hypothesized that the increased risk of thrombogenesis in PAD may be related to abnormal angiogenesis and, thus, an increased risk of future vascular disease. To test this hypothesis, we measured plasma levels of tissue factor (TF) and related levels to indices of angiogenesis, that is vascular endothelial growth factor (VEGF) and its soluble receptor sFlt-1. We studied 234 patients (145 males; mean age 68.6+/-10 years) with proven PAD (ankle brachial pressure index <0.8) and compared them with 50 healthy controls. Levels of VEGF ( P =0.001) and TF ( P =0.043) were increased in patients compared with controls. There were significant correlations between VEGF and TF levels in both patients (Spearman r =0.351, P <0.001) and healthy controls (Spearman r =0.335, P =0.017). Amongst PAD patients, levels of VEGF were related to gender, with women having higher levels than men. There was no difference in the levels of sFlt-1 between the patients and controls, or between the subgroups of patients. There were however significant correlations between the levels of sFlt-1 and TF (Spearman r =0.268, P <0.001) and between sFlt-1 and VEGF (Spearman r =0.499, P <0.001). In conclusion, patients suffering from proven PAD have higher plasma levels of TF and VEGF compared with controls, with a significant correlation between the two. This suggests a link between the hypercoagulable state in PAD and the process of angiogenesis.

Topics: Adult; Biomarkers; Case-Control Studies; Endothelial Growth Factors; Extracellular Matrix Proteins; Female; Humans; Intercellular Signaling Peptides and Proteins; Lymphokines; Male; Middle Aged; Neovascularization, Physiologic; Peripheral Vascular Diseases; Regression Analysis; Risk Factors; Sex Factors; Thromboplastin; Thrombosis; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

Activated platelets are implicated in the development of premature arterial vascular diseases, in particular ischemic stroke. Since elevated cytosolic [Ca(2+)](i) is an integrative marker of platelet activation, we determined the generation of Ca(2+) signal in stimulated platelets from 26 young patients recuperating from stroke, 20 patients with symptomatic peripheral arterial disease, and 56 healthy volunteers. Even in the presence of aspirin, the platelets from various individuals showed highly different thrombin-induced Ca(2+) responses. On average, the thrombin-induced Ca(2+) response was increased for platelets from either patient group in comparison to the controls (P <0.04). Relatively more stroke patients had high-responsive platelets (27%, 7/26) than patients with peripheral arterial disease (10%, 2/20) or healthy subjects (4%, 2/56). The average prothrombinase activities of platelets from patients and controls were similar, but 3 out of 6 patients with increased thrombin-induced Ca(2+) responses also exhibited high prothrombinase activity. In a follow-up study, the subject-dependent thrombin-induced Ca(2+) response was found to correlate strongly with the platelet response to protease-activated receptor 1 (PAR1) agonist (r = 0.91), but was not linked to the Pl(A1/2) polymorphism. It is concluded that a significant part of young patients with stroke have platelets with hyperactivity toward thrombin, which is not normalised by aspirin treatment. Furthermore, the subject-dependent variation in thrombin-induced signalling is likely to involve PAR1-mediated platelet activation.

Topics: Adult; Base Sequence; Blood Platelets; Calcium Signaling; Case-Control Studies; DNA; Female; Humans; In Vitro Techniques; Integrin alpha2; Integrin beta3; Male; Middle Aged; Peripheral Vascular Diseases; Platelet Activation; Polymorphism, Genetic; Receptor, PAR-1; Receptors, Thrombin; Stroke; Thrombin; Thromboplastin

Blackfoot disease is a thrombotic peripheral vascular disease causally related to the fluorescent humic acid (HA) found in the drinking water of wells in endemic areas in Taiwan. In this study we examined the effect of HA on tissue factor (TF) expression by vascular endothelial cells. Incubation of cultured human umbilical vein endothelial cells (HUVEC) with HA isolated from endemic area drinking water or with a synthetic humic acid polymer (SHA), resulted in enhanced cell surface expression of TF activity by HUVEC. The intracellular calcium level ([Ca2+]i) was measured using a calcium-specific fluorescent probe, fura 2. Changes in [Ca2+]i level were followed and quantitatively analyzed by spectrofluorometric microscopy, after incubation of the fura 2-loaded HUVEC with HA or SHA in a medium containing 1.8 mM CaCl2. Both HA and SHA increased [Ca2+]i in the presence of extracellular calcium ions, but not in their absence, indicating that influx of extracellular Ca2+ occurred during incubation of HUVEC with HA or SHA. Verapamil, a potent calcium channel blocker, did not abolish the enhancement of [Ca2+]i induced by HA or SHA, indicating that specific calcium channels may not be involved in the HA/SHA-induced elevation of [Ca2+]i. The elevated [Ca2+]i level induced by HA or SHA returned to basal level following removal of HA or SHA and incubation of the washed cells in medium containing 1.8 mM CaCl2. All these changes occurred in the absence of significant cytotoxic effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; Calcium; Cells, Cultured; Endothelium, Vascular; Humans; Humic Substances; Intracellular Fluid; Isoquinolines; Peripheral Vascular Diseases; Piperazines; Protein Kinase C; Taiwan; Thromboplastin; Umbilical Veins; Verapamil; Water Supply

Topics: Arterial Occlusive Diseases; Blood Coagulation; Humans; Peripheral Vascular Diseases; Thromboplastin; Thrombosis