DU-176b, a potent and orally active factor Xa inhibitor: in vitro and in vivo pharmacological profiles

Summary.  Background:  Factor Xa (FXa), a key serine protease that converts prothrombin to thrombin in the coagulation cascade, is a promising target enzyme for the prophylaxis and treatment of thromboembolic diseases. DU-176b is a novel antithrombotic agent that directly inhibits FXa activity. Objective:  To evaluate the in vitro pharmacological profiles and in vivo effects of DU-176b in animal models of thrombosis and bleeding. Methods: In vitro , FXa inhibition, specificity and anticoagulant activities were examined. Oral absorption was studied in rats and cynomolgus monkeys. In vivo effects were studied in rat and rabbit models of venous thrombosis and tail bleeding. Results: DU-176b inhibited FXa with Ki values of 0.561 n m for free FXa, 2.98 n m for prothrombinase, and exhibited >10 000-fold selectivity for FXa. In human plasma, DU-176b doubled prothrombin time and activated partial thromboplastin time at concentrations of 0.256 and 0.508 μ m , respectively. DU-176b did not impair platelet aggregation by ADP, collagen or U46619. DU-176b was highly absorbed in rats and monkeys, as demonstrated by more potent anti-Xa activity and higher drug concentration in plasma following oral administration than a prototype FXa inhibitor, DX-9065a. In vivo , DU-176b dose-dependently inhibited thrombus formation in rat and rabbit thrombosis models, although bleeding time in rats was not significantly prolonged at an antithrombotic dose. Conclusions:  DU-176b is a more potent and selective FXa inhibitor with high oral bioavailability compared with its prototype, DX-9065a. DU-176b represents a promising new anticoagulant for the prophylaxis and treatment of thromboembolic diseases.     

Conjugated linoleic acid preserves muscle mass in mice bearing the Lewis lung carcinoma, but not the B16 melanoma

Conjugated linoleic acid (CLA), which is found in dairy products, reduces synthesis of tumor necrosis factor-alpha (TNFa), a pro-inflammatory cytokine that plays a major role in tumor-induced skeletal muscle wasting (SMW). The B16 melanoma expresses TNFa mRNA, and induced SMW with no change in muscle levels of TNFa type 1 receptor (TNFR1) protein. A diet containing .5% CLA had no effect on SMW or TNFR1 in mice bearing B16 tumors. In contrast, the Lewis lung carcinoma expresses low levels of TNFa mRNA, induced SMW, and increased muscle levels of TNFR1. A diet containing .5% CLA reduced SMW, but had no effect on muscle levels of TNFR1. We conclude that that tumor-induced SMW can occur independent of muscle levels of TNFR1. Further study is needed before CLA can be tested in persons with cancer cachexia.     

氧化苦参碱对B16-BL6细胞转移作用的影响

目的 探讨氧化苦参碱抗肿瘤转移的作用及其作用机制.方法 在黑色素瘤细胞(B16-BL6细胞株)培养液中加入梯度浓度(0、1、10、20、50、100μmol/L)的氧化苦参碱,并采用MTT法检测肿瘤细胞增殖抑制率.采用静脉注射方法建立肿瘤转移小鼠模型,以低剂量和高剂量(20 mg/kg,40 mg/kg)两个剂量组灌胃治疗,23 d后解剖小鼠对肺部转移灶计数观察.并取定量肺组织,取匀浆.以ELISA法检测金属蛋白酶MMP-2,MMP-9的含量.结果 在体外实验中氧化苦参碱可抑制黑色索瘤细胞的增殖,并存在量效关系.IC50值为38.6 μmol/L.动物实验中低剂量和高剂量组肺部转移灶都比模型组少,并有显著差异(P ＜0.05或P＜0.01).低剂量和高剂量组的肺组织的MMP-2,MMP-9的表达量均减少,与模型组比较有显著差异(P＜0.05或P＜0.01).结论 氧化苦参碱对肿瘤细胞有抑制作用,并可抗肿瘤转移,其作用部分机制可能与抑制金属蛋白酶MMP-2,MMP-9表达有关.     

Inhibitors of COX activity preserve muscle mass in mice bearing the Lewis lung carcinoma, but not the B16 melanoma

Tumor-induced skeletal muscle wasting (SMW) contributes to the fatigue and weakness experienced by persons with cancer cachexia. Tumor necrosis factor-alpha (TNFa) and cyclooxygenase (COX) activity have been implicated in SMW in some animal models of cancer cachexia. We report that indomethacin, a nonspecific inhibitor of COX, and NS398, a specific inhibitor of COX2, preserved muscle mass and reduced type 1 TNF receptors in muscles of mice bearing the Lewis lung carcinoma, but not in mice bearing the B16 melanoma. These data suggest that tumor-induced SMW can occur via a COX2-independent pathway. The COX2-dependent pathway may involve reducing the catabolic effects of TNFa in muscle. Further study is needed to understand the relationship between COX and SMW, and whether patients with cancer cachexia might benefit from COX inhibitors.     

Effect of vascular injury on inhibition of venous thrombosis with ZK-807834, a direct inhibitor of factor Xa

Summary.  Inhibition of factor Xa with the small molecule inhibitor ZK-807834 (Mr 527 Da, K_i 0.11 nM) attenuates progression of thrombosis, but the ED₅₀ is substantially lower for venous compared with arterial thrombosis in experimental animals. To determine whether this reflects differences in the extent of vascular injury, we compared the dose–response of ZK-807834 for inhibition of venous thrombosis induced with a cotton thread and copper wire device in the presence and absence of balloon catheter-induced injury to the vena cava in rabbits. ZK-807834 administration over 2 h (total dosages of 0.0023–2.3 µmol kg⁻¹, n  = 6/group) resulted in dose-dependent reductions in clot weight compared with vehicle controls, but the ED₅₀ was 0.03 µmol kg⁻¹ for non-injured veins and 0.42 µmol kg⁻¹ for injured veins. We conclude that vascular injury invokes a tissue factor-mediated response that increases the dose requirements for inhibition of venous thrombosis with ZK-807834.     

Effects of the oral,direct factor Xa inhibitor rivaroxaban on commonly used coagulation assays

Summary. Introduction: Rivaroxaban is an oral direct factor Xa inhibitor developed for prophylaxis and treatment of thromboembolic disorders. Laboratory monitoring is not necessary but the dose‐dependent effects on common reagents and assay procedures are largely unknown. Objectives: To investigate the effect of rivaroxaban on commonly used coagulation assays. Materials and Methods: Rivaroxaban was added to plasma from healthy subjects in the concentration range 0–1000 μg L^?1 and analyzed using different reagents for activated partial thromboplastin time (APTT), prothrombin time (PT), antithrombin, fibrinogen and activated protein C (APC) resistance assays. Results: At an expected peak concentration of rivaroxaban in clinical use, the APTTs were almost invariably prolonged but at lower concentrations the effect was weak. The concentration needed to double the APTT varied between 389 ± 106 and 617 ± 149 μg L^?1 for different reagents. The PT assays showed a marked degree of difference. In general, the Quick PT type assays were more sensitive compared with the Owren type PT assays. The results from antithrombin assays were dependent on the type of reagent, with the Xa‐based assay being sensitive for rivaroxaban with an estimated increase of 0.09 IU mL^?1 per 100 μg L^?1 rivaroxaban. There were only minor effects on fibrinogen assays based on thrombin reagents. The APTT‐based assay for APC resistance is affected in a dose‐dependent manner whereas an assay based on the activation of coagulation at the prothrombinase level was unaffected. Conclusions: Different assays, and even different reagents within an assay group, display variable effects by therapeutic concentrations of rivaroxaban.     

Arterial antithrombotic and bleeding time effects of apixaban,a direct factor Xa inhibitor,in combination with antiplatelet therapy in rabbits

Summary. Background: Optimal treatment of arterial thrombosis may include a combination of antiplatelet and anticoagulant drugs. We evaluated apixaban, a direct and highly selective factor Xa inhibitor, in combination with clinically relevant doses of aspirin and/or clopidogrel for prevention of arterial thrombosis in rabbits. Methods: Studies were conducted in rabbit models of electrically induced carotid artery thrombosis and cuticle bleeding time (BT). Apixaban 0.04 and 0.3 mg kg^?1 h^?1 or aspirin 1 mg kg^?1 h^?1 was infused intravenous (i.v.) continuously from 1 h before artery injury or cuticle bleed until the end of the experiment. Clopidogrel at 3 mg kg^?1 was dosed orally once daily for three days, with the last dose given 2 h before injury. Results: Control thrombus weight and BT averaged 8.6 ± 0.9 mg and 181 ± 12 s, respectively (n = 6 per group). Effective doses of apixaban that reduced thrombus weight by 20 and 50% (ED₂₀ and ED₅₀) were 0.04 and 0.3 mg kg^?1 h^?1 i.v., respectively. Addition of aspirin to apixaban ED₂₀ and ED₅₀ significantly reduced the thrombus weight from 7.4 ± 0.5 to 5.3 ± 0.3 and 3.6 ± 0.3 mg, respectively, with no significant increases in BT (190 ± 7 s vs.181 ± 9 and 225 ± 11 s, respectively). Addition of aspirin and apixaban (ED₂₀ dose) to clopidogrel produced a further significant reduction in thrombus weight from 5.3 ± 0.3 to 0.7 ± 0.1 mg. This combination of clopidogrel and aspirin with apixaban (ED₂₀ dose) produced a significant but moderate BT increase of 2.1 times control. Conclusions: The combination of apixaban and aspirin or apixaban, aspirin and clopidogrel can reduce formation of occlusive arterial thrombosis without excessive increases in BT in rabbits.     

Etoposide loaded solid lipid nanoparticles for curtailing B16F10 melanoma colonization in lung

Poor solubility of etoposide and associated poor bioavailability of the drug was circumvented by developing solid lipid nanocarrier system. The objective of the research work was to prepare etoposide loaded solid lipid nanoparticles (SLN) for improved efficacy and therapy of metastasized cancers. Entrapment of drug into nanoparticulate system modifies the pharmacokinetic and biodistribution profile of the drug with improved therapeutic efficacy. Solid lipid nanoparticles of various triglycerides were prepared using hot homogenization technique. Further, the process and formulation parameters viz. homogenization cycle and pressure, type of lipid were optimized. Developed nanoparticles were characterised for particle size, in vitro dissolution studies, DSC thermogram, surface morphology and cytotoxicity assay. Pharmacokinetic and biodistribution study were performed to assess the distribution of the drug in vivo. Modulation of the therapeutic activity of the drug was studied by performing antimetastatic activity on a B16F10 melanoma mouse model. The obtained results exhibited suitability of trimysristin for fabrication of nanoparticles. Characterisation of nanoparticles depicted formation of homogenous, spherical particles entrapping approximately 50% of the drug. The results for the performed MTT assay suggested that the developed nanoparticles exhibited cytotoxicity in a time- and concentration-dependent fashion. These findings concord with the results of the in vitro dissolution profile. Pharmacokinetic parameters demonstrated increase in area under curve (AUC), t_1/2 and mean residence time (MRT) for drug in plasma. Further there is enhancement in the ratio of the drug that reaches to the highly perfused organs (upon encapsulation into solid lipid nanoparticles). Generally, cancer cells metastasized through the blood or lymphatic system. Accumulation of the drug in the highly perfused organ suggests suitability of the developed nanoparticles for targeting metastasized tumors. This was proved by the findings of the in vivo B16F10 mouse melanoma model. Improvement in the tumoricidal activity and survival rate of the animals substantiates the application of nanoparticles for improved therapeutic activity of etoposide.     

The efficacy and safety of apixaban, an oral, direct factor Xa inhibitor, as thromboprophylaxis in patients following total knee replacement.

BACKGROUND: Heparins and warfarin are currently used as venous thromboembolism (VTE) prophylaxis in surgery. Inhibition of factor (F) Xa provides a specific mechanism of anticoagulation and the potential for an improved benefit-risk profile. OBJECTIVES: To evaluate the safety and efficacy of apixaban, a potent, direct, oral inhibitor of FXa, in patients following total knee replacement (TKR), and to investigate dose-response relationships. PATIENTS/METHODS: A total of 1238 patients were randomized to one of six double-blind apixaban doses [5, 10 or 20 mg day(-1) administered as a single (q.d.) or a twice-daily divided dose (b.i.d.)], enoxaparin (30 mg b.i.d.) or open-label warfarin (titrated to an International Normalized Ratio of 1.8-3.0). Treatment lasted 10-14 days, commencing 12-24 h after surgery with apixaban or enoxaparin, and on the evening of surgery with warfarin. The primary efficacy outcome was a composite of VTE (mandatory venography) and all-cause mortality during treatment. The primary safety outcome was major bleeding. RESULTS: A total of 1217 patients were eligible for safety and 856 patients for efficacy analysis. All apixaban groups had lower primary efficacy event rates than either comparator. The primary outcome rate decreased with increasing apixaban dose (P = 0.09 with q.d./b.i.d. regimens combined, P = 0.19 for q.d. and P = 0.13 for b.i.d. dosing).A significant dose-related increase in the incidence of total adjudicated bleeding events was noted in the q.d. (P = 0.01) and b.i.d. (P = 0.02) apixaban groups; there was no difference between q.d. and b.i.d. regimens. CONCLUSIONS: Apixaban in doses of 2.5 mg b.i.d. or 5 mg q.d. has a promising benefit-risk profile compared with the current standards of care following TKR.     

A dose escalation study of YM150, an oral direct factor Xa inhibitor, in the prevention of venous thromboembolism in elective primary hip replacement surgery

BACKGROUND: YM150, a new oral direct factor Xa inhibitor is used as prophylaxis for venous thromboembolism (VTE), a well-known risk after orthopaedic surgery. OBJECTIVES: To assess the safety and efficacy of thromboprophylaxis with YM150 in a dose escalation study. PATIENTS/METHODS: Patients (174) undergoing hip replacement surgery were randomized per cohort to oral once daily YM150 or subcutaneous enoxaparin (40 mg daily) in a 4:1 ratio for 7-10 days treatment. The YM150 doses were 3, 10, 30 and 60 mg by sequential four-dose escalation cohorts. The primary endpoint was major and/or clinically relevant non-major bleeding. The incidence of VTE was defined as a composite of verified symptomatic events and/or positive findings at bilateral venography on the last treatment day. An independent adjudication committee evaluated blindly the outcomes of the open-label study. RESULTS: No major and three clinically relevant non-major bleeds were reported, 1 (2.9%; 95% CI, 0.1-15.1) in the 3 mg and 2 (5.7%; 95% CI, 1.0-18.8) in the 10 mg YM150 dose groups. Of 147 patients (84%) with an evaluable venogram, VTE was observed in 51.9% (95% CI, 31.9-71.4), 38.7% (95% CI, 22.6-57.0), 22.6% (95% CI, 9.7-39.4), and 18.5% (95% CI, 7.5-36.5) in the YM150 dose groups 3, 10, 30 and 60 mg, respectively. A significant YM150 dose-related trend in VTE incidence was found (P=0.006). VTE with enoxaparin was 38.7% (95% CI, 22.6-57.0). CONCLUSIONS: YM150, 10-60 mg daily, starting 6-10 h after primary hip replacement, was shown to be safe, well tolerated and effective.     

A dose‐ranging study evaluating the oral factor Xa inhibitor edoxaban for the prevention of venous thromboembolism in patients undergoing total knee arthroplasty

Summary. Background: Edoxaban (the free base of DU‐176b) is an oral, direct factor (F)Xa inhibitor in clinical development for the prevention and treatment of thromboembolic events. Objectives: The aim of the present study was to evaluate the efficacy and safety of edoxaban for the prevention of venous thromboembolism (VTE) in patients undergoing total knee arthroplasty (TKA). Patients/methods: This was a randomized, double‐blind, placebo‐controlled, multicenter study conducted in Japan. A total of 523 Japanese patients were assigned to receive edoxaban 5, 15, 30 or 60 mg once daily or placebo for 11–14 days. A placebo control was used as neither low‐molecular‐weight heparin (LMWH) nor fondaparinux had been approved for thromboprophylaxis at the time of the study in Japan. The primary efficacy outcome was the incidence of VTE (lower‐extremity deep vein thrombosis, symptomatic pulmonary embolism or symptomatic deep vein thrombosis). The primary safety outcome was the incidence of major and clinically relevant non‐major bleeding. Results: Edoxaban produced a significant dose‐related reduction in VTE: the incidence of VTE was 29.5%, 26.1%, 12.5% and 9.1% in the edoxaban 5‐, 15‐, 30‐ and 60‐mg treatment groups vs. 48.3% in the placebo group. The incidence of major and clinically relevant non‐major bleeding was similar across all groups without any significant differences among edoxaban doses or between edoxaban and placebo. Conclusions: Edoxaban demonstrated significant dose‐dependent reductions in VTE in patients undergoing TKA with a bleeding incidence similar to placebo. [This trial is registered with JAPIC, JapicCTI‐060283 (ja).]     

Favorable therapeutic index of the direct factor Xa inhibitors, apixaban and rivaroxaban, compared with the thrombin inhibitor dabigatran in rabbits

Summary.  Background: Apixaban is an oral, direct factor Xa (FXa) inhibitor in late-stage clinical development. This study assessed effects of the direct FXa inhibitors, apixaban and rivaroxaban, vs. the direct thrombin inhibitor, dabigatran, on venous thrombosis (VT), bleeding time (BT) and clotting times in rabbits. Methods: We induced the formation of non-occlusive thrombus in VT models by placing threads in the vena cava, and induced bleeding by the incision of cuticles in anesthetized rabbits. Apixaban, rivaroxaban and dabigatran were infused IV to achieve a stable plasma level. Clotting times, including the activated partial thromboplastin time (aPTT), prothrombin time (PT), modified PT (mPT) and thrombin time (TT), were measured. Results: Apixaban, rivaroxaban and dabigatran exhibited dose-related efficacy in preventing VT with EC₅₀ of 65, 33 and 194 n m , respectively. At doses for 80% reduction of control thrombus, apixaban, rivaroxaban and dabigatran prolonged BT by 1.13 ± 0.02-, 1.9 ± 0.1-* and 4.4 ± 0.4-fold*, respectively (* P  <   0.05, vs. apixaban). In the treatment model, these inhibitors equally prevented growth of a preformed thrombus. Antithrombotic doses of apixaban and rivaroxaban prolonged aPTT and PT by <3-fold with no effect on TT. Dabigatran was ≥50-fold more potent in prolonging TT than aPTT and PT. Of the clotting assays studied, apixaban, rivaroxaban and dabigatran responded the best to mPT. Conclusion: Comparable antithrombotic efficacy was observed between apixaban, rivaroxaban and dabigatran in the prevention and treatment of VT in rabbits. Apixaban and rivaroxaban exhibited lower BT compared with dabigatran at equivalent antithrombotic doses. The clinical significance of these findings remains to be determined.     

Prevention of venous thromboembolism with an oral factor Xa inhibitor,YM150, after total hip arthroplasty. A dose finding study (ONYX‐2)

Background: Anticoagulant prophylaxis substantially reduces the risk of venous thromboembolism (VTE) after major orthopedic surgery. The direct factor Xa inhibitor YM150 is currently under investigation for the prevention of VTE, stroke and ischemic vascular events in patients after orthopedic surgery, with atrial fibrillation and with acute coronary syndrome, respectively. Objectives: To investigate the efficacy and safety of YM150 for the prevention of VTE following elective total hip arthroplasty. Patients/methods: Patients were randomized to postoperative, once‐daily, oral YM150 (5, 10, 30, 60 or 120 mg) (double‐blind) or preoperative subcutaneous (open label) enoxaparin (40 mg) for 5 weeks. The primary efficacy endpoint comprised VTE diagnosed by mandatory bilateral venography or verified symptomatic deep vein thrombosis (DVT) plus all deaths up to 9 days after surgery. The primary safety outcome was major bleeding up to 9 days after surgery. Results: Primary efficacy endpoint: of 1017 patients randomized, 960 patients were evaluable for safety and 729 patients for efficacy. A dose‐related decrease in VTE incidence from YM150 5 to 60 mg (P = 0.0005) and from 5 to120 mg (P = 0.0002) was found. The VTE incidence was 27.4%, 31.7%, 19.3%, 13.3% and 14.5% for 5, 10, 30, 60 and 120 mg YM150, respectively, and 18.9% for enoxaparin. Primary safety endpoint: there was one major bleed with YM150 (60 mg) and one with enoxaparin. Conclusions: The oral direct FXa inhibitor YM150 demonstrated a significant dose response regarding efficacy. Doses from 30 to 120 mg had comparable efficacy to enoxaparin, without compromising safety regarding major bleeding events.     

First experience with direct, selective factor Xa inhibition in patients with non-ST-elevation acute coronary syndromes: results of the XaNADU-ACS Trial.

BACKGROUND: Unfractionated heparin is widely used in patients with non-ST-elevation acute coronary syndromes but has important limitations. Anticoagulants with predictable kinetics and anticoagulant effects, better efficacy, and greater safety are needed. OBJECTIVE: To investigate the efficacy and safety of a direct, selective factor Xa inhibitor, DX-9065a (Daiichi Pharmaceuticals LTD, Inc.) compared with heparin, in patients with non-ST-elevation acute coronary syndromes. PATIENTS AND METHODS: Patients (n = 402) from the USA, Canada, and Japan were randomized to blinded, weight-adjusted heparin, low-dose DX-9065a, or high-dose DX-9065a. RESULTS: The primary efficacy endpoint of death, myocardial infarction, urgent revascularization, or ischemia on continuous ST-segment monitoring occurred in 33.6%, 34.3%, and 31.3% of patients assigned to heparin, low-dose DX-9065a, and high-dose DX-9065a (P = 0.91 for heparin vs. combined DX-9065a). The composite of death, myocardial infarction, or urgent revascularization occurred in 19.5%, 19.3%, and 11.9% (P = 0.125 for heparin vs. high-dose DX-9065a) of patients; major or minor bleeding occurred in 7.7%, 4.2%, and 7.0% of patients; and major bleeding in 3.3%, 0.8%, and 0.9% of patients. Higher concentrations of DX-9065a were associated with a lower likelihood of ischemic events (P = 0.03) and a non-significant tendency toward a higher likelihood of major bleeding (P = 0.32). CONCLUSIONS: In this small phase II trial, there was a non-significant tendency toward a reduction in ischemic events and bleeding with DX-9065a compared with heparin in patients with acute coronary syndromes. The absence of an effect on ST-monitor ischemia warrants further investigation. These data provide the rationale for adequately powered studies of DX-9065a in acute coronary syndromes or percutaneous intervention.     

Preservation of in vitro function of platelets stored in the presence of a synthetic dual inhibitor of factor Xa and thrombin

BACKGROUND: The use of citrate anticoagulant limits the clinical significance of platelet function tests. Thrombin inhibitors cannot prevent thrombin-induced platelet activation completely. We examined the influence of benzylsulfonyl-d-Arg-Pro-4-amidinobenzylamide (BAPA), a dual inhibitor of Factor Xa (FXa) and thrombin, on platelet responsiveness to agonists when measured between 2 and 24 h after venipuncture. METHODS: Blood samples from 36 individuals were anticoagulated with citrate and BAPA, respectively. Turbidimetric platelet aggregometry (TPA) and impedance platelet aggregometry (IPA), a whole blood platelet counting assay for measuring platelet aggregation (PCA), and Platelet Function Anlayzer-100 (PFA-100 closure times (CTs) were determined after whole blood storage between 2 and 24 h after venipuncture. Native whole blood was studied over 48 h to determine the inhibition of thrombin generation by BAPA, hirudin and melagatran. RESULTS: BAPA inhibited thrombin generation completely for 48 h, while hirudin and melagatran did not. The use of citrate resulted in significantly reduced TPA induced by arachidonic acid (AA) or adenosine 5'-diphosphate (ADP), and significantly reduced IPA regardless of agonist when measured 10 and 24 h after blood collection. PCA ratios in citrated blood also dropped significantly 10 and 24 h after venipuncture. The length of storage of BAPA-anticoagulated blood samples over 24 h had no significant influence on any platelet response. The reproducibility of platelet function assay results obtained from BAPA-anticoagulated samples was significantly better than corresponding data from citrated blood. CONCLUSION: TPA, IPA, PCA or PFA-100 CTs remain stable for 24 h when whole blood is anticoagulated with a dual inhibitor of FXa and thrombin. This would greatly simplify the shipment of samples for platelet function testing.     

Effect of SanOrg123781A, a synthetic hexadecasaccharide, on clot-bound thrombin and factor Xa in vitro and in vivo

Summary. Factor (F)Xa and thrombin bound to the clot during its formation contribute to the propensity of thrombi to activate the coagulation system. The aim of this work was to study the inhibition of clot‐bound FXa and clot‐bound thrombin by SanOrg123781A, a synthetic hexadecasaccharide that enhances the inhibition of thrombin and FXa by antithrombin (AT). SanOrg123781A, designed to exhibit low non‐specific binding to proteins other than AT, was compared with heparin. In buffer, heparin and SanOrg123781A inhibited FXa and thrombin at similar concentrations [concentration inhibiting 50% (IC₅₀) of Xa and IIa activity were, respectively: heparin 120 ± 7 and 3 ± 1 ng mL^?1; SanOrg123781A 77 ± 5 and 4 ± 1 ng mL^?1]. In human plasma, the activity of both compounds was reduced, although the activity of heparin was much more affected than that of SanOrg123781A (IC₅₀ values for inhibition of FXa and FIIa activity were, respectively: heparin 100 ± 5 and 800 ± 40 ng mL^?1; SanOrg123781A 10 ± 5 and 30 ± 3 ng mL^?1). We demonstrated, in agreement with our previous results, that the procoagulant activity of the clot is essentially due to clot‐bound FXa and to some extent to clot‐bound thrombin. We showed that heparin and SanOrg123781A were able to inhibit fragment F1+2 generation induced by clot‐bound FXa with IC₅₀ values of 2 ± 0.5 µg mL^?1 and 0.6 ± 0.2 µg mL^?1, respectively. Both compounds also inhibited clot‐bound thrombin activity, the IC₅₀ values of heparin and SanOrg123781A being 1 ± 0.01 µg mL^?1 and 0.1 ± 0.1 µg mL^?1, respectively. Moreover, both heparin and SanOrg123781A significantly inhibited fibrinopeptide A generated by the action of clot‐bound thrombin on fibrinogen but also by free thrombin generated from prothrombin by clot‐bound FXa with IC₅₀ values of 4 ± 0.6 and 1 ± 0.1 µg mL^?1, respectively. As with clot‐bound enzymatic activities, SanOrg123781A was three times more active than heparin in vivo on fibrinogen accretion onto a pre‐existing thrombus and as activators of recombinant tissue‐type plasminogen activator‐induced thrombolysis. In conclusion, due to the specific activities of SanOrg123781A, this compound is much more active than heparin in the presence of plasma proteins, on clot‐bound enzymes and in in vivo models of thrombosis/thrombolysis.     

T-钙黏蛋白对B16F10黑素瘤细胞周期调节的研究

目的探讨T-钙黏蛋白对B16F10黑素瘤细胞周期的影响。方法应用脂质体LipofectamineTM2000将构建的pEGFP-N1-T-钙黏蛋白以及pEGFP-N1空载体转染至B16F10细胞,OPTI-MEM培养基体外培养6 h后RPMI-1640继续培养24 h,应用碘化丙啶标记,流式细胞仪检测T-钙黏蛋白对B16F10黑素瘤细胞周期的影响。结果转染T-钙黏蛋白组G0/G1期和G2/M期细胞比率分别为(60.917±1.897)%、(8.513±0.651)%,明显高于未转染组的(53.563±1.856)%、(2.627±0.434)%和pEGFP-N1空载体组的(53.880±2.164)%、(2.770±0.466)%,差异有显著性(P<0.05);转染T-钙黏蛋白组S期细胞比率为(30.570±1.368)%,低于未转染组的(43.810±2.003)%及pEGFP-N1空载体组的(43.350±2.629)%,差异有统计学意义(P<0.05)。未转染组与转染pEGFP-N1空载体组各期差异均无统计学意义(P>0.05)。结论 T-钙黏蛋白使B16F10细胞G0/G1期和G2/M期比率增高,S期比率降低。     

BAY 59-7939: an oral, direct Factor Xa inhibitor for the prevention of venous thromboembolism in patients after total knee replacement. A phase II dose-ranging study

BACKGROUND: BAY 59-7939, a novel, oral, direct factor Xa inhibitor, is in clinical development for the prevention of venous thromboembolism (VTE), a frequent complication following orthopaedic surgery. METHODS: In a multicenter, parallel-group, double-blind, double-dummy study, 621 patients undergoing elective total knee replacement were randomly assigned to oral BAY 59-7939 (2.5, 5, 10, 20, and 30 mg b.i.d., initiated 6-8 h postsurgery), or subcutaneous enoxaparin (30 mg b.i.d., initiated 12-24 h postsurgery). Treatment was continued until mandatory bilateral venography 5-9 days after surgery. The primary efficacy endpoint was a composite of any deep vein thrombosis (proximal and/or distal), confirmed non-fatal pulmonary embolism and all-cause mortality during treatment. The primary safety endpoint was major, postoperative bleeding during treatment. RESULTS: Of the 613 patients treated, 366 (59.7%) were evaluable for the primary efficacy analysis. The primary efficacy endpoint occurred in 31.7%, 40.4%, 23.3%, 35.1%, and 25.4% of patients receiving 2.5, 5, 10, 20 and 30 mg b.i.d. doses of BAY 59-7939, respectively (test for trend, P = 0.29), compared with 44.3% in the enoxaparin group. The frequency of major, postoperative bleeding increased with increasing doses of BAY 59-7939 (test for trend, P = 0.0007), with no significant difference between any dose group compared with enoxaparin. Bleeding endpoints were lower for the 2.5-10 mg b.i.d. doses compared with higher doses of BAY 59-7939. CONCLUSIONS: Oral administration of 2.5-10 mg b.i.d. of BAY 59-7939, early in the postoperative period, showed potential efficacy and an acceptable safety profile, similar to enoxaparin, for the prevention of VTE in patients undergoing elective total knee replacement.     

表皮生长因子调控核因子κB诱导卵巢上皮性癌紫杉醇耐药的作用及机制

目的探讨表皮生长因子(EGF)中上调的核因子κB(NF-κB)诱导卵巢上皮性癌(EOC)紫杉醇耐药的作用及机制。方法选取江苏省徐州市陆军第七十一集团军医院妇产科2015年1月至2019年1月收治的EOC亲本细胞系(A2780细胞)和紫杉醇耐药细胞系(A2780/Taxol细胞)及所对应的裸鼠实验分成A组(A2780组)、B组(A2780+CRM197组)、C组(A2780/Taxol组)、D(A2780/Taxol+CRM197组)四组,A组和C组加入100μg/ml DMSO培养基培养24 h,B组和D组加入100μg/ml CRM197培养基培养24 h。同时按NF-κB在紫杉醇的IC50及P-gp蛋白表达中的表达情况将上述分组细分成A1组(空载体)、B1组(NF-κB+siRNA组)、C1组(空载体+CRM197组)、D1组(NF-κB siRNA+CRM197组)。所有纳入者的肝素结合表皮生长因子(HB-EGF)和表皮生长因子受体(EGFR)表达均采用双重免疫荧光染色法检测,NF-κB表达采用蛋白印迹法检测,而裸鼠移植瘤组织(A2780/Taxol组与A2780/Taxol+CRM197组)中EGFR和P-糖蛋白(P-gp)表达则采用免疫组化SP法检测。结果C、D组HB-EGF、EGFR、NF-κB表达均低于A、B组,裸鼠移植瘤组织中NF-κB表达均低于A、B组(P<0.05),同时C组以上三项指标的表达及裸鼠移植瘤组织中NF-κB表达均高于A组(P<0.05),单NF-κB表达来看,EOC患者(A、B、C、D组)的NF-κB表达均低于裸鼠移植瘤组织中NF-κB表达(P<0.05)。B1、C1、D1组A2780/Taxol细胞对紫杉醇的IC50及P-gp蛋白表达均明显显著低于A1组,而B1、C1、D1组细胞内Rh123荧光强度则明显高于A1组(P<0.05);D1组A2780/Taxol细胞对紫杉醇IC50及P-gp蛋白表达均低于B1、C1组,Rh123荧光强度高于B1、C1组(P<0.05),其中B1与C1组的IC50、P-gp表达和Rh123荧光强度均无显著差异(P>0.05)。A2780/Taxol+CRM197组EGFR、P-gp表达强度均低于A2780/Taxol组(P<0.05)。结论在EOC的治疗中,EGF可通过调控EGFR、NF-κB、P-gp等信号通路而诱导其对紫杉醇产生耐药,NF-κB表达与EOC的紫杉醇耐药有相关性。     

Tissue factor pathway inhibitor-γ is an active alternatively spliced form of tissue factor pathway inhibitor present in mice but not in humans

Summary.  Background:  Tissue factor pathway inhibitor (TFPI) is a potent inhibitor of tissue factor procoagulant activity produced as two alternatively spliced isoforms, TFPIα and TFPIβ, which differ in domain structure and mechanism for cell surface association. 3' Rapid amplification of cDNA ends was used to search for new TFPI isoforms. TFPIγ, a new alternatively spliced form of TFPI, was identified and characterized. Methods:  The tissue expression, cell surface association and anticoagulant activity of TFPIγ were characterized and compared to those of TFPIα and TFPIβ through studies of mouse and human tissues and expression of recombinant proteins in Chinese hamster ovary (CHO) cells. Results:  TFPIγ is produced by alternative splicing using the same 5'-splice donor site as TFPIβ and a 3'-splice acceptor site 276 nucleotides beyond the stop codon of TFPIβ in exon 8. The resulting protein has the first two Kunitz domains connected to an 18 amino acid C-terminal region specific to TFPIγ. TFPIγ mRNA is differentially produced in mouse tissues but is not encoded within the human TFPI gene. When expressed in CHO cells, TFPIγ is secreted into conditioned media and effectively inhibits tissue factor procoagulant activity. Conclusions:  TFPIγ is a third alternatively spliced form of TFPI that is widely expressed in mouse tissues but not made by human tissues. It contains the first two Kunitz domains and is a secreted, rather than a cell surface-associated, protein. It is a functional anticoagulant and may partially explain the resistance of mice to coagulopathy in tissue factor-mediated models of disease.