Correlation between endogenous VWF:Ag and PK parameters and bleeding frequency in severe haemophilia A subjects during three-times-weekly prophylaxis with rFVIII-FS.

Patients with severe haemophilia A experience frequent and spontaneous bleeding, causing debilitating damage to joints and decreasing quality of life. Prophylaxis with factor VIII (FVIII) reduces joint damage if initiated early. Circulating FVIII levels may be influenced by endogenous von Willebrand factor (VWF), a chaperone protein that binds and stabilizes FVIII. The aim of this study was to determine whether endogenous VWF antigen (VWF:Ag) levels are correlated with FVIII pharmacokinetic (PK) parameters and clinical outcomes in patients with severe haemophilia A. Previously treated, non-inhibitor patients in a multinational, randomized, double-blind, Ph II study received prophylaxis with once-weekly BAY 79-4980 (35 IU kg(-1)) or thrice-weekly recombinant sucrose-formulated FVIII (rFVIII-FS; 25 IU kg(-1)). PK parameters were evaluated at weeks 1 and 26. The number of bleeds per patient during the study was captured as part of the core efficacy endpoint. Spearman rank correlations assessed relationships of VWF:Ag levels with patient age, PK and annualized bleeding rate. Of 131 study patients (aged 13-64 years; BAY 79-4980, n = 63; rFVIII-FS, n = 68), 27 (21%; n = 15 and 12 respectively) were evaluable for PK assessment. Baseline VWF:Ag levels correlated with patient age (P < 0.0001). There was no significant difference in PK results between treatments; thus, PK parameters and VWF levels of all patients were analysed together. AUC(norm) and T1/2 significantly increased with increased VWF:Ag (P < 0.001); clearance significantly decreased with increased VWF:Ag (P = 0.002). Annualized bleeding rate in patients treated with 3× per week rFVIII-FS significantly correlated with VWF:Ag and age (P = 0.038 and 0.021 respectively). PK parameters as well as the clinical outcome significantly correlated with endogenous VWF:Ag. The improved clinical outcome in subjects with high VWF:Ag levels may be explained by VWF:Ag influence on FVIII PK.

Identification of a VWF peptide antagonist that blocks platelet adhesion under high shear conditions by selectively inhibiting the VWF-collagen interaction.

BACKGROUND: Because the collagen-VWF-GPIb/IX/V axis plays an important role in thrombus formation, it represents a promising target for development of new antithrombotic agents. OBJECTIVES: We used phage display to identify potential small peptides that interfere with the VWF-collagen binding and might serve as lead products for the development of possible oral antithrombotic compounds. METHODS: A random linear heptamer peptide library was used to select VWF-binding peptides. RESULTS: We identified a phage clone, displaying the YDPWTPS sequence, further referred to as L7-phage, that bound to VWF in a specific and a dose-dependent manner. This L7-phage specifically inhibited the VWF-collagen interaction under both static and flow conditions. Epitope mapping using deletion mutants of VWF revealed that the L7-phage does not bind to the known collagen-binding A3 domain within VWF, but to the more carboxyterminal situated C domain. This inhibition was not due to steric hindrance of the A3 domain-collagen interaction by the L7-phage. Indeed, a tetrabranched multi-antigen peptide (MAP) presenting four copies of the peptide, but not the scrambled MAP, also inhibited VWF-collagen interaction under conditions of high shear stress at a concentration of 148 nmol L(-1). CONCLUSIONS: Based on these results, we conclude that we have identified the first peptide antagonist that binds to the VWF C domain and by this specifically inhibits the VWF binding to collagen, suppressing platelet adhesion and aggregation under high shear conditions. As a consequence, this peptide and its future derivates are potentially interesting antithrombotic agents.

Stimulatory effect of Cinnamomum cassia and cinnamic acid on angiogenesis through up-regulation of VEGF and Flk-1/KDR expression.

Complementary and alternative medicine, Cinnamomum cassia is one of the medicinal plants that have been used to improve various diseases caused by insufficient blood circulation. However, relatively little work has been carried out on the angiogenic responses of C. cassia and its active compound cinnamic acid (CA), despite its excellent pharmacological action. In this study, we study the effect of the ethanol extract of C. cassia (CCE) and its active compound CA, on angiogenic processes in in vitro and in vivo. In the Matrigel plug assay in vivo, CCE and CA dose dependently increased von Willebrand Factor (vWF) antigen expression, and hemoglobin contents, whose elevation paralleled the onset of angiogenesis and was considered an early indicator of endothelial activation. CCE and CA induced endothelial cells proliferation, migration and tubule-like structure in vitro. The 25-50% increase observed with CCE (at low doses of 1 or 10 ng/ml) in HUVEC and BAEC proliferation was similar to that observed with CA. The migration and tubule-like structure effect were observed with HUVEC and BAEC. However, the effect of CCE, CA and VEGF on cell proliferation, migration and tubule-like structure in HUVEC were bigger than the effect of CCE, CA and VEGF in BAEC. In addition, CCE and CA each induced 2.2-fold and 2.5-fold increases the production of VEGF, the mRNA expression of VEGF and Flk-1/KDR, the receptor involved in proliferation, migration, and tubule-like structure of endothelial cells. These data suggest that CCE and its active compound CA induce angiogenesis in vivo and in vitro, and this pathway is related with VEGF and Flk-1/KDR expression of endothelial cells.

Prevalence of von Willebrand disease in women with iron deficiency anaemia and menorrhagia in Taiwan.

Iron deficiency anaemia (IDA) is a frequently encountered disease, which can be attributed to menorrhagia. Most female patients with von Willebrand disease (VWD) have menorrhagia. The aim of this study was to investigate the prevalence of VWD in women with both IDA and menorrhagia in Taiwan. From January to December 2005 and November 2006 to January 2007, 56 consecutive patients with both IDA and menorrhagia were enrolled in this study. Their median age was 41 years (range 18-53). IDA was diagnosed by anaemia plus either low ferritin or transferrin saturation. Menorrhagia was evaluated by patient's menses history. Both von Willebrand factor antigen (VWF:Ag) and ristocetin cofactor activity (VWF:RCo) were measured for each patient. Bleeding time (BT) and platelet function analyser (PFA)-100 assay were determined as ancillary tests. The VWD diagnosis was established if: (i) both VWF:Ag (<50%) and VWF:RCo (<50%) were low; (ii) either VWF:Ag or VWF:RCo was low plus prolonged BT or prolonged PFA closure times. VWF multimer analysis was performed for subtype confirmation of VWD. Nine of the 56 (16.1%) patients were identified to have VWD. VWD patients with menorrhagia might develop IDA at younger age (34.3 vs. 39.7, P = 0.09) and had more IDA recurrence (75% vs. 16%, P = 0.03) than those patients without VWD. Of the eight VWD patients with VWF multimer analyses, all were revealed to have type I VWD. Our study demonstrates that VWD was not uncommon in women with both IDA and menorrhagia in Taiwan.

Effect of chronic exercise and Angiotensin-converting enzyme inhibition on rodent thoracic aorta.

Vascular reactivity can be modulated by local physical factors as well as pharmacologic manipulations. The aim of this study was to evaluate the effects of chronic exercise (EX) with or without the ACEI captopril (CAP) on vascular reactivity. Sixty-four Sprague-Dawley male rats were randomized into 4 groups (n = 16): group 1, control; group 2, captopril; group 3, exercise; and group 4, exercise and captopril. After 10 weeks of treatment, rats were killed, and their thoracic aortas harvested. Vascular reactivity was studied in an organ chamber (n = 12). Aortic endothelium constitutive nitric oxyde synthase (NOS3) expression was determined by Western blot analysis (n = 4). Endothelial-dependent relaxation was increased in both CAP and EX rats relative to the control group. Maximal aortic relaxations were enhanced in the CAP group, and potencies of these mediators were enhanced in the EX group (P < 0.05 versus control). Combined treatment did not result in a synergistic effect. NOS3 relative expressions were: group 1, 100%; group 2, 241%; group 3, 64%; and group 4, 108%. Exercise enhanced both potencies and efficacies of the mediators studied, whereas CAP increased mainly their efficacies. NOS3 protein expression was up-regulated in CAP-treated rats but not in exercised rats. These findings suggest different mechanisms for the observed increased vascular reactivity.

Inhibition of lung carcinogenesis and effects on angiogenesis and apoptosis in A/J mice by oral administration of green tea.

Oral administration of tea (Camellia sinensis) has been shown to inhibit the formation and growth of several tumor types in animal models. The present study investigated the effects of treatment with different concentrations of green tea on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in female A/J mice. Two days after a single dose of NNK (100 mg/kg body weight, i.p.), the mice were given 0.1, 0.2, 0.4, and 0.6% green tea solution (1, 2, 4, and 6 g of tea solids, respectively, dissolved in 1 l of water), 0.02% caffeine, or water as the sole source of drinking fluid until the termination of the experiment. Only the treatment with 0.6% tea preparation significantly reduced lung tumor multiplicity (mean +/- SE, 6.07 +/- 0.77 vs. 8.60 +/- 0.50 tumors per mouse, P = 0.018). Treatment with 0.6% tea also inhibited angiogenesis, as indicated by the lower microvessel density (number of blood vessels/mm2) based on immunostaining for the von Willebrand factor antigen (81.9 +/- 9.5 vs. 129.4 +/- 8.2, P = 0.0018) and anti-CD31 antibody staining (465.3 +/- 61.4 vs. 657.1 +/- 43.6, P = 0.0012). Significantly lower vascular endothelial growth factor immunostaining scores were also observed in the 0.6% tea-treated group (0.98 +/- 0.17 vs. 1.43 +/- 0.07, P = 0.006). The apoptosis index was significantly higher in lung adenomas from 0.6% tea-treated mice based on morphological analysis of cell apoptosis (2.51 +/- 0.18% vs. 1.57 +/- 0.11%, P = 0.00005), and the result was further confirmed using the TUNEL method. Inhibition of angiogenesis and the induction of apoptosis by green tea may be closely related to the inhibition of pulmonary carcinogenesis.

[Myocardial protection and mechanism of Puerarin Injection on patients of coronary heart disease with ischemia/reperfusion].

OBJECTIVE: To explore the protective effect and the mechanism of Puerarin Injection (PI) on myocardial ischemia reperfusion in patients with coronary heart disease (CHD) and angina pectoris (AP). METHODS: Seventy-eight patients with AP planned to receive the PTCA and stenting treatment were randomly divided and single-blindedly into the conventional group and the PI group. Based on the conventional treatment and pre-operational preparation, the PI group was given 200 ml of PI by intravenous dripping once a day, beginning from one week before operation, but to the conventional group, normal saline was given for instead. The condition of AP attack in balloon dilatatory stage of PTCA was observed and change of ST segment of ECG detected by a 12-lead ECG monitor. The blood levels of von Willebrand factor (vWF:Ag), nitric oxide (NO) and endothelin-1 (ET-1) were also observed before and after treatment. RESULTS: As compared with those in the conventional group, number of patients having AP attack and ST segment change in PTCA process was lessened in the PI group, with blood levels of vWF:Ag and ET-1 obviously lower, and NO content obviously higher than those in the conventional group, CONCLUSIONS: PI could protect the myocardium in 2-3 days after ischemia reperfusion, one of the possible reasons is that PI can simulate the late phase of ischemic preconditioning, which may be related to its effect in lowering plasma vWF:Ag and ET-1, and increasing the serum NO content.

A new approach to antiplatelet therapy: inhibitor of GPIb/V/IX-vWF interaction.

Evidence has been presented that the interaction between von Willebrand factor (vWF) and its platelet membrane receptor, the GPIb/V/IX complex, plays an important role in the pathogenesis of arterial thrombosis. A monoclonal antibody against the A1 domain of vWF has been shown to inhibit thrombus formation in the animal model of arterial thrombosis. Based upon these findings, a new approach to treating arterial thrombosis has been proposed by intervening in the interaction between vWF and platelet.

Prevention of arterial thrombosis using a novel heparin with enhanced antiplatelet activity and reduced anticoagulant activity.

PURPOSE: Thrombosis after arterial injury is often initiated by von Willebrand factor (vWF)-dependent platelet accumulation. A promising antithrombotic strategy is the interruption of platelet/vWF interactions. Previously, we demonstrated how chemical and affinity modification can enhance heparin's anti-vWF activity while reducing conventional anticoagulation. Here, we investigated whether a modified heparin can block platelet-dominated arterial thrombosis. METHODS: Standard heparin was oxidized with periodate, refined to have high vWF affinity and inhibitory potency, and tested in a guinea pig model of platelet-dependent arterial thrombosis. In this model, a controlled mechanical arterial injury yields cyclic flow variations (CFVs) caused by recurrent accumulation of platelet thrombi. RESULTS: All six control animals developed CFVs (mean, 10.4 +/- 2.6 CFVs), and six of seven animals treated with standard heparin also developed CFVs (mean, 7.6 +/- 4.6). Only one of six animals treated with the anti-vWF heparin and one of six treated with AJvW-2 (an anti-vWF antibody) developed CFVs (mean, 2.0 +/- 4.9 and 0.5 +/- 1.2, respectively). Thus both the modified heparin and AJvW-2 were more effective than standard heparin (p < 0.03). Bleeding times and platelet counts were unaffected. A modified activated partial thromboplastin time was less prolonged by the modified high-affinity heparin (91 +/- 17) seconds) than by standard heparin (144 +/- 30 seconds; p < 0.01). CONCLUSIONS: The modified heparin with high vWF affinity was a more effective arterial antithrombotic agent, with fewer conventional anticoagulant effects than standard heparin. Interruption of the vWF/platelet interaction is a promising antithrombotic strategy that may be met by novel heparin-based antithrombotic drugs.