Assessing Plasmin Generation in Health and Disease.

Fibrinolysis is an important process in hemostasis responsible for dissolving the clot during wound healing. Plasmin is a central enzyme in this process via its capacity to cleave fibrin. The kinetics of plasmin generation (PG) and inhibition during fibrinolysis have been poorly understood until the recent development of assays to quantify these metrics. The assessment of plasmin kinetics allows for the identification of fibrinolytic dysfunction and better understanding of the relationships between abnormal fibrin dissolution and disease pathogenesis. Additionally, direct measurement of the inhibition of PG by antifibrinolytic medications, such as tranexamic acid, can be a useful tool to assess the risks and effectiveness of antifibrinolytic therapy in hemorrhagic diseases. This review provides an overview of available PG assays to directly measure the kinetics of plasmin formation and inhibition in human and mouse plasmas and focuses on their applications in defining the role of plasmin in diseases, including angioedema, hemophilia, rare bleeding disorders, COVID-19, or diet-induced obesity. Moreover, this review introduces the PG assay as a promising clinical and research method to monitor antifibrinolytic medications and screen for genetic or acquired fibrinolytic disorders.

A Systemwide Approach for Navigating the Dilemma of Oral Factor Xa Inhibitor Interference With Unfractionated Heparin Anti-Factor Xa Concentrations.

BACKGROUND: Oral factor Xa inhibitors are known to significantly increase heparin anti-Xa concentrations, which leads to inaccuracies when monitoring intravenous unfractionated heparin (IV UFH). Guidance for managing this laboratory interference is lacking, creating substantial uncertainty in clinical practice. OBJECTIVE: To describe a strategy used by a large academic institution for managing the controversy of laboratory interference in the setting of oral factor Xa inhibitor use and provide effectiveness and safety data for this approach. METHODS: In December 2016, a new Heparin IV Direct Oral Anticoagulant (DOAC) Interference PowerPlan (a comprehensive order set) was made available in the electronic health record (Cerner, North Kansas City, MO) throughout the health system. We retrospectively examined 169 patients with events reported in the error reporting system, RISKMASTER, and evaluated reports with and without the use of the PowerPlan. Effectiveness was determined through evaluation of thrombosis. The Naranjo criteria for causality were applied to assess thrombotic events. RESULTS: Of 56 events that were reported with apixaban when the PowerPlan was not ordered, 4 (7%) thrombotic events occurred within 7 days of UFH initiation. One out of the 4 events (25%) that occurred when the PowerPlan was not appropriately initiated was considered probable using the Naranjo Scale. Three additional events (75%) were possible using the Naranjo Scale. CONCLUSION AND RELEVANCE: The Heparin IV DOAC Interference PowerPlan appears to be conducive to positive patient outcomes when evaluating voluntary reported events and may assist clinicians with managing the therapeutic dilemma of this laboratory interference.

Development and validation of HPLC-UV method for quantitation of a new antithrombotic drug in rat plasma and its application to pharmacokinetic studies.

A selective and sensitive procedure for quantitation of a new antithrombotic drug (GRS) in rat plasma was developed and validated using an HPLC-UV. The method was validated according to recommendations of the FDA, EMA in terms of selectivity, linearity, accuracy, precision, recovery, matrix effect, stability, and carry-over. The preparation of the biological sample included liquid-liquid extraction with acetonitrile, separation of water-organic mixture with inorganic salts, organic phase clean-up with a sorbent (QuEChERS method), its evaporation to dryness and reconstitution of the residue with A:B eluents mixture (1:1). The chromatographic separations were performed on a micro-column 75 × 2 mm, 5 µm particle size sorbent ProntoSIL 120-5-C18 AQ. The flowrate was of 0.15 ml/min, detector wavelength was set at 360 nm for GRS and at 230 nm for papaverine (IS). It was found that GRS recovery from rat plasma is 94%, the response linearity is in the range of 10 to 1000 ng ml-1. The accuracy values for intra-day determination were of 93.2 to 101.8%, for inter-day determination were of 91.2 to 102.2%, coefficient of variation for intra- and inter-day precision did not exceed 4.1 to 9.3%. The application of the method was shown in pharmacokinetic studies of GRS in rats at a dose of 20 mg kg-1.

Safety and Pharmacokinetics of DS-1040 Drug-Drug Interactions With Aspirin, Clopidogrel, and Enoxaparin.

DS-1040, a novel low-molecular-weight inhibitor of activated thrombin-activatable fibrinolysis inhibitor, is under development for the treatment of thromboembolic diseases including venous thromboembolism and acute ischemic stroke. Here we describe the results of 3 studies that evaluated the safety and tolerability of DS-1040 along with the effect on DS-1040 pharmacokinetic (PK) parameters, when dosed alone or when coadministered with aspirin (NCT02071004), clopidogrel (NCT02560688), or enoxaparin in healthy subjects. Concomitant administration of single-dose DS-1040 with multiple-dose aspirin, multiple-dose clopidogrel, or single-dose enoxaparin, consistent with clinically relevant dose regimens, was safe and well tolerated with no serious treatment-emergent adverse events (TEAEs), TEAEs leading to discontinuation, bleeding-related TEAEs, and no significant changes in coagulation parameters. DS-1040 did not prolong bleeding time when administered concomitantly with aspirin or clopidogrel. In the aspirin study, DS-1040 PK was evaluated following the concomitant administration with multiple-dose aspirin, where the plasma DS-1040 exposure (peak plasma concentration [Cmax ] and area under the concentration-time curve [AUCinf ]) was to be similar to the data previously published in the first-in-human study of DS-1040 in healthy subjects. The PK parameters of DS-1040 coadministered with clopidogrel were similar to those of DS-1040 alone, with small increases in geometric means for Cmax (7%) and AUClast (9%). When coadministered with enoxaparin, the PK parameters of DS-1040 were not affected (1.1% and 1.5% decreases in geometric means for Cmax and AUClast , respectively). Therefore, concomitant administration of DS-1040 and clopidogrel or enoxaparin did not demonstrate PK drug-drug interactions.

Anti-Xa assays: What is their role today in antithrombotic therapy?

Although some suggest anti-Xa assays should be the preferred method for monitoring intravenous unfractionated heparin therapy, which method is best is unknown owing to the lack of large randomized controlled trials correlating different assays with clinical outcomes. This article provides an overview of heparin monitoring and the pros, cons, and clinical applications of anti-Xa assays.

Early Complement and Fibrinolytic Activation in a Rat Model of Blast-Induced Multi-Organ Damage.

OBJECTIVE: Blast injury is associated with multi-organ failure (MOF), causing significant morbidity and mortality in trauma patients. However, the pathogenesis of blast-induced MOF still remains obscure. In this study, we evaluate the pathophysiological changes related to blast-induced MOF in a clinically relevant rat model of blast injury. METHODS: A moderate blast overpressure was applied to induce injury in anesthetized rats. Pathological changes were evaluated by H&E staining. Complement activation, plasminogen, and myeloperoxidase levels were analyzed by complement hemolytic assay (CH50) and/or ELISA in blood samples. RESULTS: Analysis of lung, brain, and liver tissue at 24 hour after blast overpressure revealed severe injuries. The level of complement components C3 and C1q decreased in parallel with the reduction of CH50 level in injured animals at 1, 3, and 6 hours after blast. Consumption of plasminogen was also detected as early as 1 hour post-injury. Myeloperoxidase levels were elevated within 1 hour of blast injury. CONCLUSION: Our data reveal that blast injury triggers the complement and fibrinolytic systems, which likely contribute to blast-induced MOF. Conceivably, therapies that target these systems early may improve clinical outcomes in blast patients.

Fibrinogen concentrate replacement in ischemic stroke patients after recombinant tissue plasminogen activator treatment.

BACKGROUND: Post-thrombotic intracerebral hemorrhage (ICH) is experienced by 6-8% of stroke patients and is associated with multiple factors, including acquired coagulopathy induced by the thrombolytic drug. OBJECTIVES: The objective of this study was to assess the outcome of the intravenous (IV) administration of fibrinogen concentrate in a series of acute stroke patients who developed iatrogenic fibrinogen critical depletion after IV thrombolysis. MATERIAL AND METHODS: Of the 39 ischemic stroke patients treated with IV thrombolysis with a severe hypofibrinogenemia requiring infusion with IV fibrinogen concentrate, 30 patients were treated with 2 g of IV recombinant tissue plasminogen activator (rt-PA), followed by further doses until the fibrinogen level reached 200 mg/dL in hemorrhagic patients or 100 mg/dL in non-hemorrhagic patients, and 9 were treated with IV rt-PA followed by endovascular thrombectomy. RESULTS: Preand post-thrombolysis National Institutes of Health Stroke Scale (NIHSS) scores were statistically different for the Cochran-Mantel-Haenszel test overall (p = 0.0002), at 24-hour evaluation (p = 0.0455) and at 7-day assessment (p = 0.0006). Within the first 7 days post-thrombolysis, the brain computed tomography (CT) scans showed that 20/39 (51.28%) patients had ICH. Of the whole sample, 25.6% of the ICH patients had symptomatic intracerebral hemorrhage (SICH), according to National Institute of Neurological Disorders and Stroke (NINDS) classification. After rt-PA treatment, the median pre-thrombolysis fibrinogenemia of 332 mg/dL significantly dropped to 133 mg/dL (p < 0.0001). After the fibrinogen concentrate infusion, the median level of fibrinogenemia rose to 160 mg/dL, which was significantly higher than the median postthrombolysis levels (p < 0.0001). Recanalization was observed in 25/28 patients (89.29%): complete in 18 and partial in 7 patients. After fibrinogen IV infusion, no thrombotic complications were seen in 37 out of 39 patients (94.77%); 2/39 (0.05%) patients experienced a pulmonary embolism, 1 of them a segmental one. CONCLUSIONS: This study showed the clinical safety of administering IV fibrinogen concentrate in order to increase plasma fibrinogen levels in a series of acute stroke patients with iatrogenic fibrinogen depletion after IV thrombolysis.

Dimethyl 2,2'-[2,2'-(ethane-1,1-diyl)bis(1H-indole-3,2-diyl)]-diacetate: a small molecule capable of nano-scale assembly, inhibiting venous thrombosis and inducing no bleeding side effect.

BACKGROUND: Due to the discovery that deep venous thrombosis (DVT) inhibitor is of chemotherapeutic importance, the nano-property of dimethyl 2,2'-[2,2'-(ethane-1,1-diyl) bis(1H-indole-3,2-diyl)]-diacetate (DEBIC), a recently reported antitumor agent, is worthy of characterization. MATERIALS AND METHODS: One-pot reaction was used to prepare DEBIC. Electrospray Ionization (+/-)-Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometer (ESI(+/-)-FT-ICR-MS), quadrupole Collision Induced Dissociation (qCID) and nuclear overhauser effect spectroscopy spectra were used to present the assembly of DEBIC. Transmission electron microscopy, scanning electron microscopy, atomic force microscopy and Faraday-Tyndall effect were used to visualize the nano-property of DEBIC. Rat models were used to evaluate DVT inhibition and the bleeding reaction of DEBIC. RESULTS: One-pot reaction can provide DEBIC in acceptable yield and high purity. In water, rat plasma and lyophilized powders of DEBIC existed as particles of small nano-size. In vivo DEBIC inhibited DVT in a dose-dependent manner. The minimal effective dose of DEBIC was 1.7 µmol/kg. Even the dose of 36 µmol/kg/day DEBIC did not induce bleeding side effect in DVT rats like in warfarin (0.82 µmol/kg/day). CONCLUSION: DEBIC is a small molecule capable of nano-scale assembly, inhibiting venous thrombosis and inducing no bleeding side effect.

Simultaneous determination of Pyragrel, a novel anti-thrombotic agent, and its two primary metabolites in plasma by HPLC-MS/MS.

Pyragrel is a novel thromboxane A2-synthetase inhibitor for the treatment of cerebral infarction, and it is currently being investigated in phase I clinical trials. This paper reports the first reliable LC-MS/MS method for the simultaneous determination of Pyragrel and its two main metabolites, M1 and M2, in human plasma. All analytes were extracted from human serum using liquid-phase extraction and separated on a Zorbax EcLipse XDB C18 column using isocratic elution with a mobile phase composed of methanol, water and formic acid (65:35:0.1, v/v/v). Determination of the analytes was achieved by tandem-mass spectrometry with positive electrospray ionization. The multiple reaction monitoring transitions under positive electrospray ionization were performed at m/z 329.0 → m/z 135.9 for Pyragrel, m/z 303.1 → m/z 135.0 for M1, m/z 331.2 → m/z 135.0 for M2, and 482.2 → m/z 258.0 for IS, respectively. The following parameters were validated: specificity, recovery, matrix effects, carry-over, linearity, sample stability under a variety of storage and handling conditions, and stock solution stability. The validated method has been successfully applied to an initial pharmacokinetic study in healthy volunteers following intravenous administrations of 60 mg of Pyragrel, and this method will facilitate further studies involving more comprehensive identification of the metabolic profile of Pyragrel and the appropriate dosage regimen.

Pharmacokinetics of a Novel Anagrelide Extended-Release Formulation in Healthy Subjects: Food Intake and Comparison With a Reference Product.

Anagrelide is an established therapy for essential thrombocythemia. Common adverse effects have been linked to peak plasma concentrations of anagrelide and its 3OH metabolite. Our study was performed to investigate the pharmacokinetics (PK) of a novel anagrelide extended-release (AER) formulation and its active metabolites. Thirty healthy volunteers were randomized to receive either 2 mg AER (under fasting and fed conditions) or 2 mg commercially available reference product (CARP) in an open-label, 3-way crossover trial with washout periods of 6 days. Plasma concentrations of anagrelide and its active metabolites were assessed by tandem mass spectrometry. The PK differed significantly between all treatment periods. Bioavailability of AER was 55% of the CARP under fasting conditions and 60% under fed conditions. Cmax , AUCt, and AUC∞ were significantly higher and Tmax and T1/2 were significantly shorter after the CARP compared with AER. Food had a significant impact on the PK of AER, increasing the Cmax and AUCt while reducing the T1/2 , plateau, and mean residence time. Both formulations were well tolerated, with a trend toward more frequently occurring adverse events after the CARP. The PK of AER and the CARP differed significantly in all parameters. Food enhanced the bioavailability of AER.

Measuring Direct Oral Anticoagulants.

Direct oral anticoagulants (DOACs) can be quantified using methods that can be performed in any clinical or research laboratory using manual or automated instrument platforms. Dabigatran etexilate, the oral direct thrombin inhibitor, can be quantified by drug-calibrated clot or chromogenic-based assays using either thrombin or ecarin as substrates. Oral direct anti-Xa inhibitors, such as rivaroxaban, apixaban, and edoxaban, can be quantified with drug-calibrated anti-Xa kits or reagents as typically used for measuring heparins (unfractionated, low molecular weight, or pentasaccharides).

A long-acting PAI-1 inhibitor reduces thrombus formation.

Plasminogen activator inhibitor 1 (PAI-1) is the main inhibitor of tissue-type and urokinase-type plasminogen activators (t/uPA) and plays an important role in fibrinolysis. Inhibition of PAI-1 activity prevents thrombosis and accelerates fibrinolysis, indicating that PAI-1 inhibitors may be used as effective antithrombotic agents. We previously designed a PAI-1 inhibitor (PAItrap) which is a variant of inactivated urokinase protease domain. In the present study, we fused PAItrap with human serum albumin (HSA) to develop a long-acting PAI-1 inhibitor. Unfortunately, the fusion protein PAItrap-HSA lost some potency compared to PAItrap (33 nM vs 10 nM). Guided by computational method, we carried out further optimisation to enhance inhibitory potency for PAI-1. The new PAItrap, denominated PAItrap(H37R)-HSA, which was the H37R variant of PAItrap fused to HSA, gave a six-fold improvement of IC50 (5 nM) for human active PAI-1 compared to PAItrap-HSA, and showed much longer plasma half-life (200-fold) compared to PAItrap. We further demonstrated that the PAItrap(H37R)-HSA inhibited exogenous or endogenous PAI-1 to promote fibrinolysis in fibrin-clot lysis assay. PAItrap(H37R)-HSA inhibits murine PAI-1 with IC50 value of 12 nM, allowing the inhibitor to be evaluated in murine models. Using an intravital microscopy, we demonstrated that PAItrap(H37R)-HSA blocks thrombus formation and platelet accumulation in vivo in a laser-induced vascular injury mouse model. Additionally, mouse tail bleeding assay showed that PAItrap(H37R)-HSA did not affect the global haemostasis. These results suggest that PAItrap(H37R)-HSA have the potential benefit to prevent thrombosis and accelerates fibrinolysis.

Effect of Panax notoginseng saponins on the pharmacokinetics of aspirin in rats.

Aspirin (ASA) is widely used to treat fever, pain, inflammation and cerebral infarction in clinic. Panax Notoginseng Saponins (PNS) is the extracts of Panax Notoginseng (PN)-a traditional Chinese medicine extensively used in cardiovascular diseases. Panax notoginseng saponins and ASA are both widely used to treat cerebral infarction in China. Good results in clinical practice have been achieved when the two drugs were taken together. To investigate the effect of PNS on ASA in vivo, the concentrations of salicylic acid (SA) in blood were measured after oral administration of ASA or ASA combined with PNS by UPLC-MS/MS. Sample preparation was carried out by the protein precipitation technique with an internal Saikosaponin A standard. The separation of two components was achieved by using an ACQUITY UPLC ®BEH C18 Column (1.7µm 2.1×100mm) by gradient elution using water (containing 0.2% formic acid) and acetonitrile (containing 0.2% formic acid) as the mobile phase at a flow rate of 0.2mL/min. The pharmacokinetic parameters were determined by using non-compartmental analysis. The results suggested that drug-drug interaction in vivo existed between PNS and ASA. The concentration of the SA was increasing when the two drugs were administered together. The transport of ASA and SA in MDCK -MDR1 cell monolayer was used to verify this conclusion. The values of apparent permeability coefficients (Papp) were significantly increased when the two drugs were used together. This result suggested PNS could increase the gastrointestinal tract absorption of ASA and SA. These findings provide more insight for wise use of two drugs to treat or prevent cardiovascular diseases.

Repeated Oral or Subcutaneous LMWH Has similar Antithrombotic Activity in a Rat Venous Thrombosis Model: Antithrombotic Activity Correlates With Heparin on Endothelium When Orally Administered.

Low-molecular-weight heparins (LMWHs) endure as important drugs for thromboprophylaxis. Although clinical use relies on the subcutaneous (SC) route, our previous studies show that single-dose orally administered LMWHs have antithrombotic activity. Since thromboprophylaxis requires long-term treatment, we examined antithrombotic effects of subacute oral LMWHs in a rat venous thrombosis model and compared results to SC or single-dose oral administration. We measured LMWH in endothelium and plasma, weight change and complete blood counts (CBC). Oral LMWH tinzaparin (3 × 0.1 mg/kg/12 or 24 hours) or reviparin (3 × 0.025 mg/kg/24 hours) significantly decreased thrombosis compared to saline. In the subacute study (60 × 0.1 mg/kg/12 hours), oral or SC tinzaparin significantly reduced thrombosis compared to saline but not to single or 3 × 0.1 mg/kg/12 hours oral tinzaparin. Antithrombotic effects were similar between oral and SC administration. LMWH was found on endothelium following oral but not SC administration. Endothelial concentrations were significantly correlated with incidence of stable thrombi ( P = 0.021 and 0.04 for aortic and vena cava endothelium respectively, χ2 test) and total thrombi ( P = 0.003 for vena cava endothelium). Anti-Xa activity was significantly greater for oral or SC LMWH than saline and significantly greater for SC versus oral LMWH. Values for CBCs were within normal ranges (mean ± 2 SD). There was no evidence of bleeding. Weight gain was similar between groups. In conclusion, subacute oral and SC LMWH have similar antithrombotic effects. Antithrombotic activity with oral administration is correlated with endothelial LMWH concentrations but not with plasma anticoagulant activity.

Higher Tinzaparin Dosing Is Needed to Achieve Target Anti-Xa Levels in Pediatric Cardiac Intensive Care Patients.

OBJECTIVES: This study was conducted to evaluate tinzaparin dosing and therapeutic drug monitoring. DESIGN: Retrospective study. SETTING: Single tertiary-level PICU. PATIENTS: Tinzaparin doses and anti-Xa levels from all children admitted to a PICU (from October 1, 2010, to December 31, 2013) were retrospectively analyzed. Thirty-nine children, median age of 13 months (interquartile range, 73 mo), with 46 episodes of newly started therapeutic tinzaparin were identified. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Local hospital policy is to determine the first anti-Xa level after 3-4 doses, 4 hours post dose, targeting 0.5-1.0 IU/mL for therapeutic dosing. First anti-Xa levels were determined after 3.8 (± 2.4; range, 1-14) doses and were below the target range in 37 of 46 episodes (76%) of tinzaparin use: mean, 0.30 (± 0.11) IU/mL. Tinzaparin was then increased by 23% (± 19) in 23 of 37 episodes (62%), and further anti-Xa levels were determined. In 14 episodes, further levels were not available because of cessation of tinzaparin therapy. Target anti-Xa levels, 0.69 (± 0.24) IU/mL, were eventually reached in the PICU in 22 patients after a mean of 8.8 (± 7.3) doses. In the entire cohort, the dose required to achieve target anti-Xa levels was significantly higher (+51 [± 62] U/kg; p = 0.003) than the recommended starting dose. CONCLUSIONS: Target anti-Xa levels were reached with tinzaparin dosing in PICU patients after more than 8 doses, warranting further dose-effect research. Especially in the younger age group, substantially higher dose requirements than proposed in the internationally used guidelines are required. With the results of our study, we suggest a different therapeutic drug monitoring approach than that currently used.

Development and validation of an indirect competitive ELISA for quantification of recombinant staphylokinase in rabbit plasma: Application to pharmacokinetic study.

The relatively short circulatory half-life (2-3 min) of staphylokinase is a major drawback in the development of SAK- (staphylokinase) based thrombolytic drug. A rapid and sensitive method, based on indirect competitive ELISA, was developed and validated for quantitative determination of SAK in rabbit plasma. The dynamic range of the assay varied between 0.41 ± 0.16 µg/L and 9.03 ± 0.38 µg/L (R(2) = 0.98) for SAK in rabbit plasma. There were no dilution linearity issues apparent with this assay. The precision (% CV) ranged from 4.6-9.7% for the intraassay and from 17.1-19.3% for interassay. This validated method was successfully employed for evaluation of various pharmacokinetic parameters of SAK in rabbit.

Relevance of Post-Stroke Circulating BDNF Levels as a Prognostic Biomarker of Stroke Outcome. Impact of rt-PA Treatment.

The recombinant form of tissue plasminogen activator (rt-PA) is the only curative treatment for ischemic stroke. Recently, t-PA has been linked to the metabolism of brain-derived neurotrophic factor (BDNF), a major neurotrophin involved in post-stroke neuroplasticity. Thus, the objective of our study was to investigate the impact of rt-PA treatment on post-stroke circulating BDNF levels in humans and in animals. Serum BDNF levels and t-PA/plasmin activity were measured at hospital admission and at up to 90 days in stroke patients receiving (n = 24) or not (n = 14) rt-PA perfusion. We investigated the relationships between serum BDNF with concurrent t-PA/plasmin activity, neurological outcomes and cardiovascular scores at admission. In parallel, serum BDNF levels and t-PA/plasmin activity were assessed before and after (1, 4 and 24h) the induction of ischemic stroke in rats. Our study revealed higher serum BDNF levels and better neurological outcome in rt-PA-treated than non-treated patients. However, serum BDNF levels did not predict stroke outcome when the whole cohort of stroke patients was analyzed. By contrast, serum BDNF levels when measured at admission and at day 90 correlated with cardiovascular scores, and those at day 1 correlated with serum t-PA/plasmin activity in the whole cohort of patients whereas no association could be found in the rt-PA-treated group. In rats devoid of cardiovascular risk, no difference in post-stroke serum BDNF levels was detected between rt-PA- and vehicle-treated animals and no correlation was found between serum BDNF levels and t-PA/plasmin activity. Overall, the data suggest that serum BDNF levels may not be useful as a prognostic biomarker of stroke outcome and that endothelial dysfunction could be a confounding factor when serum BDNF levels after stroke are used to reflect of brain BDNF levels.

Pharmacokinetics and Pharmacodynamics of Tissue Plasminogen Activator Administered Through an External Ventricular Drain.

BACKGROUND: Intraventricular hemorrhage (IVH) frequently complicates spontaneous intracerebral or subarachnoid hemorrhage (SAH). Administration of intraventricular tissue plasminogen activator (TPA) accelerates blood clearance, but optimal dosing has not been clarified. Using a standardized TPA dose, we assessed peak cerebrospinal fluid (CSF) TPA concentrations, the rate at which TPA clears, and the relationship between TPA concentration and biological activity. METHODS: Twelve patients with aneurysmal SAH and IVH, treated with endovascular coiling and ventricular drainage, were randomized to receive either 2 mg intraventricular TPA or placebo every 12 h (five doses). CT scans were performed 12, 48, and 72 h after initial administration, and blood was quantified using the SAH Sum and IVH Scores. CSF TPA and fibrin degradation product (D-dimer) concentrations were measured at baseline and 1, 6, and 12 h after the first dose using ELISA assays. RESULTS: Median CSF TPA concentrations in seven TPA-treated patients were 525 (IQR 352-2129), 323 (233-413), and 47 (29-283) ng/ml, respectively, at 1, 6, and 12 h after drug administration. Peak concentrations varied markedly (401-8398 ng/ml). Two patients still had slightly elevated levels (283-285 ng/ml) when the second dose was due after 12 h. There was no significant correlation between the magnitude of CSF TPA elevation and the rate of blood clearance or degree of D-dimer elevation. D-dimer peaked at 6 h, had declined by 12 h, and correlated strongly with radiographic IVH clearance (r = 0.82, p = 0.02). CONCLUSIONS: The pharmacokinetics of intraventricular TPA administration varies between individual patients. TPA dose does not need to exceed 2 mg. The optimal administration interval is every 8-12 h.

Re-evaluation of the anticoagulant properties of high-density lipoprotein-brief report.

OBJECTIVE: This study was conducted to resolve the striking controversy between our previous report that high-density lipoprotein (HDL) enhances activated protein C (APC)/protein S anticoagulant actions and a subsequent, contradicting report that HDL lacks this activity. APPROACH AND RESULTS: When fresh HDL preparations from 2 laboratories were subjected to Superose 6 column chromatography, fractions containing HDL-enhanced APC:protein S anticoagulant actions in clotting assays, thereby validating our previous report. Moreover, the ability of HDL to enhance the anticoagulant actions of APC:protein S was neutralized by anti-apoAI antibodies, further indicating that the activity is because of HDL particles and not because of contaminating phospholipid vesicles. Density gradient subfractionation studies of HDL showed that large HDL subfractions (densities between 1.063 and 1.125 g/mL) contained the APC:protein S-enhancing activity. Fresh HDL stored at 4°C gradually lost its anticoagulant enhancing activity for 14 days, indicating moderate instability in this activity of purified HDL. CONCLUSIONS: These studies conclusively demonstrate that freshly prepared HDL fractions possess anticoagulant activity. Fractions from Superose 6 columns that contain HDL reproducibly enhance APC:protein S anticoagulant activity, consistent with the hypothesis that HDL has antithrombotic activity and with the observation that low HDL levels are found in male venous thrombosis patients. Understanding the basis for this activity could lead to novel therapeutic approaches to regulate venous thrombosis.

In vivo metabolism study of xiamenmycin A in mouse plasma by UPLC-QTOF-MS and LC-MS/MS.

Xiamenmycin A is an antifibrotic leading compound with a benzopyran skeleton that is isolated from mangrove-derived Streptomyces xiamenensis. As a promising small molecule for fibrotic diseases, less information is known about its metabolic characteristics in vivo. In this study, the time-course of xiamenmycin A in mouse plasma was investigated by relative quantification. After two types of administration of xiamenmycin A at a single dose of 10 mg/kg, the plasma concentrations were measured quantitatively by LC-MS/MS. The dynamic changes in the xiamenmycin A concentration showed rapid absorption and quick elimination in plasma post-administration. Four metabolites (M1-M4) were identified in blood by UPLC-QTOF-MS, and xiamenmycin B (M3) is the principal metabolite in vivo, as verified by comparison of the authentic standard sample. The structures of other metabolites were identified based on the characteristics of their MS and MS/MS data. The newly identified metabolites are useful for understanding the metabolism of xiamenmycin A in vivo, aiming at the development of an anti-fibrotic drug candidate for the therapeutic treatment of excessive fibrotic diseases.