摘要:

Tissue factor (TF), the membrane-bound glycoprotein that normally initiates the coagulation pathway, is expressed on the surface of various cells including endothelial cells, fibroblasts, monocytes and tumor cells. We recently reported that hemoglobin (Hb) enhances TF expression and procoagulant activity on TF-bearing human A375 malignant melanoma cells. To elucidate the mechanism of Hb-induced TF expression, we studied the interaction between purified TF from human A375 malignant melanoma cells and Hb. Selective binding of highly purified melanoma cell TF-apoprotein to Hb was demonstrated under native conditions using a dot-immunobinding assay and under denaturing conditions by Western blotting. The complex formation between purified melanoma cell TF-apoprotein and Hb was also demonstrated by the binding of fluid-phase Hb to immobilized TF-apoprotein (0–2.0 μg/ml) in an enzyme-linked immunosorbent assay. The binding was specific, concentration-dependent, saturable and inhibited significantly (60%) by Concanavalin-A. Hb enhanced the factor X-activating procoagulant activity of melanoma cell TF in a concentration-dependent manner, but had no effect on recombinant human TF. Concanavalin-A and wheat germ agglutinin significantly (60%) inhibited the Hb-induced procoagulant activity of malignant cell TF. We conclude that TF-apoprotein selectively binds Hb, most probably via the carbohydrate moieties (α-d-glucosyl; α-d-mannosyl andN-acetyl-β-d-glucosaminyl residues) of TF, and enhances its procoagulant activity. The physiological significance of this interaction remains to be established.

ISSN:0957-5235    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The present study aimed to assess whether the determination of overall haemostasis potential (OHP) in plasma is powerful enough to monitor the prophylactic effect of low molecular mass heparin (dalteparin, Fragmin®) in patients with increased risk of thromboembolitic events. In five pregnant women who had a history of deep venous thrombosis, OHPs were kinetically investigated in gestation weeks 32–35 twice during 24 h (before injection and after 1, 2, 4, 6, 8, 10, 12, 14, 16 and 24 h). Levels of anti-activated factor X (anti-FXa), reflecting dalteparin activity, as well as prothrombin fragments 1 + 2 (F1 + 2) and soluble fibrin, were also measured. In converse relation to changes of anti-FXa, OHPs decreased reaching the lowest level between 2 and 8 h after the injection, and then rose again, returning to the levels around those before the administration. There were no significant variations in concentrations of F1 + 2 and soluble fibrin during the observation course. These findings indicate that the OHP assay can monitor the alteration of haemostatic balance under the dalteparin influence while anti-FXa only shows the activity of the drug present in plasma. Additionally, analyses of thrombin generation markers are not useful to screen immediate changes in the haemostatic system after dalteparin injection.

ISSN:0957-5235    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Thromboembolism is not uncommon in multiple myeloma (MM) patients on treatment, but its pathogenesis remains poorly understood. We report the results of a prospective randomized trial of 62 newly diagnosed MM patients tested at baseline for hypercoagulability and treated with intensive chemotherapy with or without thalidomide in a randomized fashion. During the induction phase, 12 patients (19%) developed evidence of deep venous thrombosis (DVT), which was significantly more common in the thalidomide arm (36%) than in the control group (3%) (P= 0.001). Fourteen patients (23%) were found to have a baseline-reduced response to activated protein C (APC) in the absence of factor V Leiden mutation. Using a Kaplan–Meier analysis, a significantly higher proportion of patients with APC resistance developed DVT (5/14 versus 7/38;P= 0.04) irrespective of thalidomide administration. The risk of DVT was highest (50%) in patients with APC resistance on thalidomide. None of the patients with normal APC response and not receiving thalidomide developed DVT. In conclusion, in this series, acquired APC resistance was present in almost one-quarter of newly diagnosed myeloma patients and significantly increased the risk of DVT.

ISSN:0957-5235    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Clot retraction is a thrombin-dependent, platelet-mediated contraction of the cellular clot mass. In this study, the effects of delayed, deficient and inhibited thrombin generation on the development of platelet contractile force (PCF) and clot elastic modulus (CEM) were measured. When normal citrated whole blood is clotted by the addition of exogenous thrombin (1 U/ml) and calcium (10 mmol/l), PCF and CEM start to develop within the first minute and begin to level off by 1200 s. If identical samples are clotted with batroxobin (0.21 μg/ml) and calcium (10 mmol/l), both PCF and CEM development are delayed approximately 5 min. After 1200 s of clotting, however, values in the batroxobin system approach those seen with exogenous thrombin. If the added calcium concentration is held constant at 10 mmol/l, increasing the exogenous thrombin concentration from 0 to 0.5 U/ml results in increased PCF and CEM values. Above 0.5 U thrombin, the effect plateaus. At exogenous calcium of 10 mmol/l, increasing batroxobin concentrations (0–0.210 μg/ml) caused a 75% increase in PCF and a 55% increase in CEM. The increase in CEM reached a plateau above 0.05 μg batroxobin/ml. The effects of varying calcium concentrations were evaluated at constant batroxobin (0.21 μg/ml) and thrombin (1 U/ml) concentrations. With thrombin, PCF and CEM increased by > 700% as CaCl2increased from 0 to 5 mmol/l. Above 5 mmol/l, no additional increases occurred. With batroxobin, PCF did not develop at CaCl2concentrations ⩽ 2.5 mmol/l. Above 2.5 mmol/l CaCl2, PCF values increased and at 10 mmol/l CaCl2were equal to those seen with thrombin. CEM in batroxobin-mediated clots peaked at 10 mmol/l CaCl2but were 40% less than the values found in thrombin-mediated clots. When the thrombin inhibitor P-PACK was added to the batroxobin system, dose-dependent decreases in PCF and CEM were noted. At 120 μmol/l, P-PACK totally suppressed PCF. PCF in blood from a factor VIII-deficient patient varied significantly when clotted with batroxobin versus thrombin. PCF development in factor VIII-deficient blood was normal with thrombin but is delayed and depressed with batroxobin. PCF values in factor VIII-deficient blood did not reach the thrombin value after 1200 s of clotting, and CEM was significantly less. These results confirm that PCF development is thrombin dependent and that delay or reduction of PCF development results in structurally weaker clots.

ISSN:0957-5235    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

A total of 260 consecutive patients, referred for hypercoagulable assessment, was included in this study. Four coagulation activation markers were utilized to assess these patients [enzyme-linked immunosorbent assays for soluble fibrin polymer (TpP), prothrombin fragment 1.2, thrombin–antithrombin complex, and D-dimer]. The mean levels of the activation markers directly correlated with the number of hypercoagulable abnormalities. The percentage of patients with increased TpP levels for each group was lower than the other activation markers. The findings indicate that activation markers reflect the number of underlying thrombophilic abnormalities. Our data suggest that there is a utility in performing a panel of coagulation activation markers to assess the thrombotic risk. The measurement of soluble fibrin polymer may be more reflective of an impending vascular event.

ISSN:0957-5235    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Recently, new missense mutations in the activated protein C (APC) cleavage sites of human factor V (FV) distinct from the R506Q (FV Leiden) mutation have been reported. These mutations affect the APC cleavage site at arginine (Arg) 306 in the heavy chain of activated FV. Whether these mutations result in APC resistance and are associated with a risk of thrombosis is not clear. The main objective of the present study was to identify the APC-resistant phenotype of FV molecules with different mutations in APC cleavage sites. To study this, recombinant FV mutants were reconstituted in FV-deficient plasma, after which normalized APC-sensitivity ratios (n-APC-SRs) were measured in activated partial thromboplastin time-based and Russell's Viper Venom time-based APC-resistance tests. The mutations introduced in FV were R306G, R306T, R506Q, R679A and combinations of these mutations. Based on the APC-sensitivity ratios, we conclude that the naturally occurring mutations at Arg306 (i.e. FV HongKong and FV Cambridge) result in a mildly reduced sensitivity for APC (n-APC-SR, 0.74–0.87), whereas much lower values (n-APC-SR, 0.41–0.51) are obtained for the mutation at Arg506 (FV Leiden). No effect on the n-APC-SR was observed for the recombinant FV mutant containing the single Ala679 mutation. Because reduced sensitivity for APC, not due to FV Leiden, is a risk factor for venous thrombosis, these data suggest that mutations at Arg306 might be associated with a mild risk of venous thrombosis.

ISSN:0957-5235    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

A raised plasma factor VII (FVII) level is one of the risk factors for coronary artery disease. The R353Q polymorphism at codon 353 and the 10 base pair (bp) insertion (0/10 bp) polymorphism of the FVII gene have been reported to be associated with plasma FVII levels in several populations. We investigated these two polymorphisms in 209 male and 214 female healthy Chinese. The allele frequencies of 10 bp and Q were 0.036 and 0.045, respectively. Strong linkage disequilibrium was observed between these two sites (Δ = 0.85,P< 0.001). There were significant genotype associations of these two loci with FVII coagulant activity (FVIIc) and antigen (FVIIAg) levels. Heterozygous individuals had lower FVIIc and FVIIAg levels than those homozygous for the common alleles. When analyzed separately by gender, the 0/10 bp polymorphism was strongly associated with FVIIAg levels in males and females. However, both polymorphisms were significantly associated with FVIIc levels only in the females. The effect of 0/10 bp polymorphism predominated over that of the R353Q polymorphism in a two-way analysis of variance procedure. In the Chinese, the 10 bp insertion may reduce transcription of the FVII gene, leading to the decreased synthesis of FVII protein and thus FVIIc.

ISSN:0957-5235    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The objective of this study was to investigate the efficacy and safety of desmopressin (1-desamino-8-d-arginine vasopressin) compared with placebo in the reduction of menstrual blood loss in women with menorrhagia and prolonged bleeding time, but without common coagulation factor deficiencies. We performed a randomized, double-blind, cross-over study using 300 μg desmopressin nasal inhalation or placebo treatment in one of the two first treatment cycles. Desmopressin was given only for the 2 days during which the bleeding had been at a maximum in the previous baseline cycle. A third open cycle involved combined treatment with desmopressin and tranexamic acid during the 2 days for all patients. Menstrual blood loss during the treatment periods was compared with blood loss during placebo-treated periods using objective measurement. A significant reduction of menstrual blood loss was found in the cycles treated with combined desmopressin and tranexamic acid compared with placebo. When analyzing the blood loss during the two treatment days, there was a significant reduction in blood loss for the 2 days with desmopressin alone versus placebo. The treatment was well tolerated and no serious adverse events were recorded. In conclusion, we find that nasal desmopressin is a possible complement for the medical treatment of menorrhagia.

ISSN:0957-5235    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

We examined whether JTV-803, a specific activated factor X inhibitor independent of antithrombin III (ATIII), is effective against disseminated intravascular coagulation (DIC) in rat models induced by tissue factor (TF) or lipopolysaccharides (LPS). In male Wistar rats, DIC was induced by a 4 h infusion of thromboplastin (3.75 U/kg) or LPS (50 mg/kg). The rats were given JTV-803 (0.3 or 3 mg/kg, bolus intravenously) (JTV-803 groups) or low molecular weight heparin (LMWH groups) (200 U/kg, bolus intravenously) prior to an injection of TF or LPS. The results showed that JTV-803 was dose-dependently effective against DIC in both TF-induced and LPS-induced rat models. This anti-DIC effect of JTV-803 at higher doses was almost equivalent to that of LMWH in both types of DIC. Plasma ATIII activity was more prominent in the group treated with JTV-803 than in that treated with LMWH. None of rats died in the TF-induced DIC model with or without drug administration. On the contrary, seven of 22 rats died (mortality rate, 31.8%) in the LPS-induced DIC model without drug administration. Although the mortality rate of rats induced with LPS and treated with LMWH was quite high (6/16, 37.5%), none of the LPS-induced rats treated with JTV-803 died. These findings suggested that JTV-803 can treat both TF-induced and LPS-induced DIC models, and that this drug has greater potential in preserving ATIII and in improving the prognosis of DIC.

ISSN:0957-5235    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

D-Dimer testing is useful for the exclusion of acute venous thromboembolism (VTE). Anticoagulant therapy is expected to reduce D-dimer levels in patients with thrombosis and, consequently, it may not be safe to use D-dimer levels to exclude VTE after anticoagulant therapy has been started. The objectives of this study were to estimate the decrease in D-dimer levels after 24 h of heparin therapy and, applying this estimate to the results of a recent study, to calculate the expected reduction in sensitivity. Using pre-defined criteria, we first performed a literature review to determine whether, and by how much, D-dimer levels decrease within 24 h of starting heparin therapy in patients with acute VTE. Using D-dimer levels that were measured in a prospective study of patients with confirmed deep vein thrombosis and/or pulmonary embolism as baselines, we then determined the change in sensitivity (and specificity) that would result from the fall in D-dimer levels that the literature review suggested would have occurred after 24 h of heparin therapy. On the basis of the literature review, we calculated that mean D-dimer levels decrease by 25%, 24 h after starting heparin therapy in patients with acute VTE. This 25% decrease in D-dimer levels resulted in a decrease in sensitivity from 95.6% (95% confidence interval, 90.0–98.6) to 89.4% (95% confidence interval, 83.7–95.1). There is a decrease in D-dimer levels in patients with acute VTE 24 h after starting heparin therapy that is expected to result in a clinically important drop in sensitivity.

ISSN:0957-5235    

出版商:OVID    

年代:2002

数据来源: OVID