Tranexamic acid (TXA) reduces surgical blood loss and alleviates inflammatory response in total hip arthroplasty. However, studies have not identified an optimal regimen. The objective of this study was to identify the most effective regimen of multiple-dose oral TXA in achieving maximum reduction of blood loss and inflammatory response based on pharmacokinetic recommendations. We prospectively studied four multiple-dose regimens (60 patients each) with control group (group A: matching placebo). The four multiple-dose regimens included: 2-g oral TXA 2 hours pre-operatively followed by 1-g oral TXA 3 hours post-operatively (group B), 2-g oral TXA followed by 1-g oral TXA 3 and 7 hours post-operatively (group C), 2-g oral TXA followed by 1-g oral TXA 3, 7 and 11 hours post-operatively (group D) and 2-g oral TXA followed by 1-g oral TXA 3, 7, 11 and 15 hours post-operatively (group E). The primary endpoint was estimated blood loss on post-operative day (POD) 3. Secondary endpoints were thromboelastographic parameters, inflammatory components, function recovery and adverse events. Groups D and E had significantly less blood loss on POD 3, with no significant difference between the two groups. Group E had the most prolonged haemostatic effect, and all thromboelastographic parameters remained within normal ranges. Group E had the lowest levels of inflammatory cytokines and the greatest range of motion. No thromboembolic complications were observed. The post-operative four-dose regimen brings about maximum efficacy in reducing blood loss, alleviating inflammatory response and improving analgaesia and immediate recovery.
Recombinant tissue-type plasminogen activator (r-tPA) was approved by U.S. Food and Drug Administration as a thrombolytic drug. However, a high dose of r-tPA (up to 100 mg/person) is typically used in clinical applications. Such high dosage leads to severe side effects including haemorrhage and neurotoxicity, which can be fatal. To improve the proteolytic properties of tPA to enhance thrombolytic therapy, we designed a series of mutants in tPA serine protease domain (tPA-SPD) based on the crystal structure of tPA-SPD:plasminogen activators inhibitor-1 (PAI-1) complex that we determined recently. We found that the A146Y substitution in tPA-SPD(A146Y) enhanced resistance to PAI-1 inactivation by 30-fold compared with original tPA-SPD. Interestingly, the tPA-SPD(A146Y) variant showed fivefold higher activation for plasminogen compared with tPA-SPD. The variant also demonstrated thrombolytic activity stronger than tPA-SPD in a clot lysis assay. In vivo, we showed tPA-SPD(A146Y) possessed higher thrombolytic efficacy in a pulmonary embolism model compared with original tPA-SPD. Furthermore, a mouse tail bleeding assay showed that tPA-SPD(A146Y) did not increase bleeding risk compared with clinical drug r-tPA. Together, our findings reveal novel functions of A146Y variant, which not only increases the catalytic efficiency of the enzyme, but also enhances resistance to PAI-1 inhibition, and demonstrating that tPA-SPD (A146Y) variant is a much improved agent for thrombolytic therapy.
Background Magnetic targeting may help microbubbles (MBs) reach obstructive thrombi and improve the efficacy of MB-mediated sonothrombolysis, but the role of magnetic targeting in MB-mediated sonothrombolysis remains elusive. Objectives We investigate the feasibility and efficacy of magnetically targeted MB-mediated sonothrombolysis for the treatment of obstructive thrombi. Materials and Methods Red and white thromboembolic models were established in vitro and in vivo. The models were randomly assigned to the control, ultrasound plus control MB (US + C-MB), ultrasound plus magnetic MB (US + M-MB), or US + M-MB + recombinant tissue-type plasminogen activator (r-tPA) groups and treated for 30 minutes. The recanalization rate, average blood flow velocity, hindlimb perfusion, and skeletal muscle injury marker levels were recorded. Results The recanalization rate, average blood flow velocity, and hindlimb perfusion in the red and white thromboembolic models were all significantly higher in the US + M-MB and US + M-MB + r-tPA groups than in the control and US + C-MB groups both in vitro and in vivo. Moreover, the levels of the skeletal muscle injury markers were all significantly lower in the US + M-MB and US + M-MB + r-tPA groups than in the other two groups in vivo for both thromboembolic models. However, the thrombolytic effects of red thrombi performed better than those of white thrombi in the US + M-MB + r-tPA group. Conclusion M-MB-mediated sonothrombolysis improves the efficacy of thrombolysis both in vitro and in vivo, and reduces tissue damage in clogging model; thus, this method may serve as a promising approach for treating thrombus-occlusive diseases.
Recently, internal jugular vein stenosis (IJVS) is gaining increasing attention from clinical researchers due to a series of confounding symptoms that impair the quality of life in affected individuals but cannot be explained by other well-established causes. In this study, we aimed to elucidate the clinical features, neuroimaging characteristics and pathogenesis of IJVS, and explore their possible correlations, in attempt to provide useful clues for clinical diagnosis and treatment. Forty-three eligible patients with unilateral or bilateral IJVS confirmed by contrast-enhanced magnetic resonance venography of the brain and neck were enrolled in this study. Magnetic resonance imaging along with magnetic resonance angiography or computed tomography angiography was applied to identify the radiological pattern of parenchymal or arterial lesions. Cerebral perfusion and metabolism were evaluated by single-photon emission computed tomography (SPECT). Of the 43 patients (46.0 +/- 16.0 years old; 30 female), 14 (32.6%) had bilateral and 29 had unilateral IJVS. The common clinical symptoms at admission were tinnitus (60.5%), tinnitus cerebri (67.6%), headache (48.8%), dizziness (32.6%), visual disorders (39.5%), hearing impairment (39.5%), neck discomfort (39.5%), sleep disturbance (60.5%), anxiety or depression (37.5%) and subjective memory decline (30.2%). The presence of bilateral demyelination changes with cloudy-like appearance in the periventricular area and/or centrum semiovale was found in 95.3% (41/43) patients. SPECT findings showed that 92.3% (24/26) patients displayed cerebral perfusion and metabolism mismatch, depicted by bilaterally and symmetrically reduced cerebral perfusion and increased cerebral glucose consumption. IJVS may contribute to alterations in cerebral blood flow and metabolism, as well as white matter lesion formation, all of which may account for its clinical manifestations.
Protein S (PS) deficiency is associated with a 10-fold increased risk of venous thromboembolism (VTE), but its diagnosis is quite difficult and complicated. In this study, we identified 53 unrelated pedigrees with PS deficiency in China. Data of their clinical characteristics and laboratory examinations were collected. Genetic analysis of PROS1 including direct sequencing, copy number variant detection and messenger ribonucleic acid analysis was performed in probands and related family members. Of these 53 probands, 52.8% (28/53) experienced multi-site and/or recurrent thrombotic episodes, mainly manifested as deep venous thrombosis and/or pulmonary embolism (82.7%). Additional risk factors of VTE were observed in 39.6% (21/53) probands who exhibited a significantly higher rate of recurrent VTE compared with those not, in which 7 probands were complicated by anti-phospholipid syndrome. Most probands and family members exhibited quantitative PS deficiency with impairment of both activated protein C and tissue factor pathway inhibitor cofactor activities. Note that 87.2% (34/39) PROS1 detectable mutation rate was obtained through comprehensive phenotypic and genetic analysis. A total of 36 PROS1 causative mutations including 16 novel mutations were identified in 48 probands, whereas no PROS1 mutations were detected in the other 5 probands. Three hotspot mutations (Glu67Ala, Arg561Trp and Tyr560*) were identified in the Chinese population for the first time. This article provides a framework for correlating the clinical pathogenesis of PS deficiency to genetic backgrounds in the Chinese population.
Background Inflammation plays an important role in thrombus formation, and Sirtuin 1 (SIRT1) negatively regulates inflammation via deacetylating nuclear factor-kappa B. However, the relationship between SIRT1-regulated inflammation and deep vein thrombosis (DVT) is still unknown. Objective The aim of this study was to investigate whether SIRT1 plays a critical role in inferior vena cava (IVC) stenosis-induced DVT. Materials and Methods Thrombus weight and histopathologic analysis of IVC were evaluated at different time points after IVC stenosis in rats. Serum levels of inflammatory cytokines and protein expressions of SIRT1, acetylated p65 (Ace-p65), phosphorylated p65 (p-p65) and tissue factor (TF) in thrombosed IVC were assessed. Besides, the effects of resveratrol (RES, a SIRT1 agonist) and EX527 (a selective SIRT1 inhibitor) on DVT were evaluated. Results Thrombus weight was increased from 1 to 3 days after IVC stenosis, and then was decreased afterwards. Leukocytes infiltration appeared and serum levels of cytokines were significantly increased in rats of IVC stenosis. SIRT1 protein expression was significantly down-regulated at 1 hour and 1 day after stenosis, while p-p65, Ace-p65 and TF protein expressions appeared a contrary trend. RES reduced thrombus weight, leukocytes infiltration, levels of tumour necrosis factor-alpha and interleukin-1 and protein expressions of Ace-p65 and TF as well. Moreover, RES significantly increased the protein and messenger ribonucleic acid expressions of SIRT1, while EX527 abolished the protective effects of RES. Conclusion SIRT1 activation attenuated IVC stenosis-induced DVT via anti-inflammation in rats. Therefore, SIRT1 may be a potential therapeutic target that could ameliorate DVT.
Immune thrombocytopaenia (ITP) is the most common autoimmune bleeding disorder, where platelets are destroyed by auto-antibodies and/or cell-mediated mechanisms. To understand the pathogenesis of ITP and explore novel therapeutics, three types of animal models have been used: passive ITP, secondary ITP and platelet-induced ITP. However, the first two are not ideal for chronic ITP pathophysiology where both T cell and B cell play important roles in platelet destruction. The most efficient model to mimic chronic ITP is developed by Chow et al through transferring splenocytes from platelet-immune CD61-knockout (KO) mice into mice with severe combined immunodeficiency (SCID). However, placental defects are evident in 25% of CD61-KO females and post-natal haemorrhage does occur, reducing the survival rate of embryos and pups. Compared with CD61-KO mice, CD41-KO ones do not present such problems. In our study, we employ CD41-KO mice as another source of immunized spleen cells. We evaluated our model with existing standards. Transferred SCID mice presented typical features of ITP, such as reduced platelet counts in the peripheral blood, increased anti-platelet antibody levels in the serum and reduced mature megakaryocytes in the bone marrow. What is more, lymphocyte-depletion experiments showed the role of CD8(+) T cells in mature megakaryocyte decrease and thrombocytopaenia. And we confirmed the antibody-mediated platelet destruction by phagocytosis in the spleen. Our study develops another efficient murine ITP model through immunized CD41-KO mice.
Background Systematic reviews reporting time trends in mortality following major orthopaedic surgery are few and have limitations. They reported on only a fraction (<15%) of the available data and did not investigate potential causes of the reduction in mortality. Methods We searched PubMed for randomized trials and observational studies, published between 1950 and 2016, reporting on mortality within 3 months of elective total hip and knee replacement (THR/TKR). Mortality risks were estimated for each 5-year interval using a Poisson regression model and presented by study design and mode of prophylaxis. To estimate the mortality reduction unrelated to anti-thrombotic use, we performed a pooled analysis of four thromboprophylaxis strategies for which data spanned five decades. Results We identified 255 eligible studies, which documented 31,604 deaths among 6,293,954 patients, and found a consistent decline in mortality irrespective of study design and mode of prophylaxis. Mortality declined from 1.15% pre-1980 to 0.24% post-2000, a 78.7% relative risk reduction (95% confidence interval [CI]: 74.7-82.1%) in randomized and cohort studies. Furthermore, our data showed a 74.4% (95% CI: 68.7-79.0%) relative reduction in mortality independent of the methods of prophylaxis, thereby indicating that improvements in peri-operative care unrelated to anti-thrombotic prophylaxis played a major role in such reduction. Conclusion Mortality following elective THR/TKR has markedly declined over the past 50 years and is now low irrespective of which prophylactic agent is being used. Although anti-thrombotic prophylaxis may have contributed, other improvements in ped-operative care played a major role in the mortality reduction.
The binding of programmed death 1 (PD-1) to its ligands PD-L1 and PD-L2 on antigen-presenting cells turns off autoreactive T cells and induces peripheral tolerance. Aberrant PD-1/PD-L signalling could result in a breakdown of peripheral tolerance and lead to autoimmune diseases. In this study, we detected PD-1 and PD-L expression on T cells and dendritic cells (DCs) in immune thrombocytopenia (ITP) patients with active disease by flow cytometry. The effects of PD-L1-Fc fusion protein (PD-L1-Fc) on T cells and on secretion of interferon-gamma (IFN-gamma) and interleukin-2 (IL-2) were detected by flow cytometry and enzyme-linked immunosorbent assay, respectively. Compared with healthy controls, PD-1 expression was significantly increased in CD4(+) T cells and CD8(+) T cells from patients with active ITP. However, PD-L1 expression on monocyte-derived DCs was lower in patients with active ITP than in healthy controls. In vitro assays revealed that PD-L1-Fc increased T cell apoptosis, inhibited activation and proliferation of CD4(+) T cells and CD8(+) T cells and decreased IFN-gamma and IL-2 secretion in patients with active ITP. These results suggest that the aberrant PD-1/PD-L negative co-stimulatory pathway may play a role in ITP. Enhancing PD-1/PD-L signalling might be a promising therapeutic approach for ITP patients by enhancing T cell apoptosis, inhibiting T cell activation and proliferation and reducing secretion of inflammatory factors.
Megakaryopoiesis produces specialized haematopoietic stem cells in the bone marrow that give rise to megakaryocytes which ultimately produce platelets. Defects in megakaryopoiesis can result in altered platelet counts and physiology, leading to dysfunctional haemostasis and thrombosis. Additionally, dysregulated megakaryopoiesis is also associated with myeloid pathologies. Transcription factors play critical roles in cell differentiation by regulating the temporal and spatial patterns of gene expression which ultimately decide cell fate. Several transcription factors have been described as regulating megakaryopoiesis including myocyte enhancer factor 2C (MEF2C); however, the genes regulated by MEF2C that influence megakaryopoiesis have not been reported. Using chromatin immunoprecipitation-sequencing and Gene Ontology data we identified five candidate genes that are bound by MEF2C and regulate megakaryopoiesis: MOV10, AGO3, HDAC1, RBBP5 and WASF2 .To study expression of these genes, we silenced MEF2C gene expression in the Meg01 megakaryocytic cell line and in induced pluripotent stem cells by CRISPR/Cas9 editing. We also knocked down MEF2C expression in cord blood-derived haematopoietic stem cells by siRNA. We found that absent or reduced MEF2C expression resulted in defects in megakaryocytic differentiation and reduced levels of the candidate target genes. Luciferase assays confirmed that genomic sequences within the target genes are regulated by MEF2C levels. Finally, we demonstrate that small deletions linked to a platelet count-associated single nucleotide polymorphism alter transcriptional activity, suggesting a mechanism by which genetic variation in MEF2C alters platelet production. These data help elucidate the mechanism behind MEF2C regulation of megakaryopoiesis and genetic variation driving platelet production.
A nonasaccharide (FG9) derived from natural fucosylated glycosaminoglycan (FG) is identified as a selective intrinsic factor Xase complex (FIXa-FVIIIa-Ca2+-phospholipid, FXase) inhibitor that possesses potential inhibition of venous thrombus in rats and shows negligible bleeding risk. The mechanism and molecular target of the nonasaccharide for intrinsic FXase inhibition were systematically investigated and compared with low molecular weight heparin (LMWH). Our results showed that FG9 dose-dependently inhibited FX activation by intrinsic FXase complex in a noncompetitive inhibition pattern, where the apparent affinity for FG9 was approximately 1.8-fold higher than that for LMWH. FG9 displayed no inhibitory effect on the activity of FIXa/phospholipid, and did not affect the decay rate of FVIIIa activity. FG9 reduced the apparent affinity of FIXa for FVIIIa in a dose-dependent manner, and accelerated the decay of intrinsic FXase complex activity. FG9 bound to FIXa with high affinity and the FIXa binding sites of FG9 were overlapped with that of LMWH, and the ability of FG-derived oligosaccharides to bind FIXa required the minimum 9 degrees of polymerization. FG9 derivatives were prepared and their structures were confirmed by one-dimensional/two-dimensional nuclear magnetic resonance. Structure-activity relationship studies showed that carboxy reduction significantly weakened its anti-FXase activity and binding affinity to FIXa, while the effects of carboxyl ethyl esterification and deacetylation were relatively weaker. Overall, our results suggest that the nonasaccharide FG9 strongly inhibits intrinsic FXase complex activity via binding to FIXa and disrupting FIXa-FVIIIa interactions, and the free carboxyl groups of FG9 are required for its potent anti-FXase activity.
Background Gamma-glutamyl transferase (GGT) has been shown to be involved in the pathogenesis of both coronary artery disease (CAD) and liver disease, and it has been reported that the GGT-to-platelet ratio (GPR) is an independent predictor for adverse outcomes from liver fibrosis and hepatic carcinoma. However, the relation between the GPR and adverse outcomes in CAD patients after percutaneous coronary intervention (PCI) has not been investigated. Methods A total of 5,636 patients enrolled in Clinical Outcomes and Risk Factors of Patients with Coronary Heart Disease after PCI, a retrospective cohort study, from January 2008 to December 2016, were divided into two groups according to GPR (GPR<0.12, n =2,769 and GPR >= 0.12, n =2,867). The primary outcome was long-term mortality including all-cause mortality (ACM) and cardiac mortality (CM) after PCI. The average follow-up time was 35.922.6 months. Results We found that there were significant differences between the two groups in the incidences of ACM ( p =0.011), CM ( p =0.001), major adverse cardiovascular events (MACEs, p <0.024), major adverse cardiovascular and cerebrovascular events (MACCEs, p =0.014) and bleeding events ( p =0.003). Multivariate Cox regression analyses showed that GPR was an independent predictor for ACM (hazard ratio [HR]: 1.536 [95% confidence interval [CI]:1.162-2.032], p =0.003), CM (HR: 1.763 [95% CI: 1.283-2.424], p <0.001), MACCEs (HR: 1.269 [95% CI: 1.066-1.511], p =0.007) and MACEs (HR: 1.308 [95% CI: 1.089-1.570], p =0.004) in stable CAD patients but that it was an independent predictor for only the incidence of bleeding events (HR: 3.104 [95% CI: 1.680-5.736], p <0.001) in acute coronary syndrome (ACS) patients. Conclusion This study indicates that GPR is an independent and novel predictor of adverse long-term outcomes in CAD patients who underwent PCI.
Background Parturient women are healthy individuals who require special consideration. Parturient women are considered to be in a hyper-coagulable state. For example, the fibrinogen (FIB) levels are often higher than the upper limit of normal reference intervals (RIs) in parturient women than in non-parturient healthy individuals (2-4 g/L). Objective The aim of this study is to establish the RIs of pro-thrombin time (PT), activated partial thromboplastin time (aPTT), FIB levels and thrombin time (TT) for parturient women. Materials and Methods Blood levels of PT, aPTT, FIB and TT were assayed on an ACL TOP 700 automatic coagulation analyser using plasma samples from 10,472 parturient women. Outlier results were excluded by using Tukey's test. The RIs were calculated by the Clinical and Laboratory Standards Institute C28-A3 guideline. Results The RIs of PT, aPTT, FIB and TT were 8.7 to 12.1seconds (8.7-12.2seconds for 16-20 years old, 8.7-12.1 second for 21-25 years old, 8.6-12.0 second for 26-30 years old, 8.7-12.0 second for 31-35 years old, 8.7-12.6 second for 36-40 years old and 8.8-12.2 second for 41 years old), 22.9 to 42.3seconds, 1.98 to 5.82 g/L and 9.9 to 16.7seconds, respectively. PT levels were found to be positively associated with aging. Conclusion The above-established age-specific RIs, defined by using a large dataset, may assist clinicians in making accurate medical decisions. This was the first study in which the RIs of PT, aPTT, FIB and TT were established for parturient women in different age groups.
The Cys22-Cys27 disulfide bond of factor X (FX) protease domain is not conserved among coagulation factors and its contribution to the physiological haemostasis and implication in the pathogenesis of haemostatic and thrombotic disorders remain to be elucidated. Mutation p.Cys27Ser was identified in a pedigree of congenital FX deficiency and fluorescence labelling study of transiently transfected HEK293 cells showed accumulation of FX p.Cys27Ser within cell, indicating incompetent secretion partially responsible for the FX deficiency. The clotting activity of FX p.Cys27Ser was decreased to about 90% of wild-type, while amidolytic and pro-thrombinase activities (kcat/Km) determined with recombinant FXa mutant were 1.33- and 4.77-fold lower. Molecular dynamic simulations revealed no major change in global structure between FXa p.Cys27Ser and wild-type FXa; however, without the Cys22-Cys27 disulfide bond, the insertion of newly formed N terminal of catalytic domain after the activation cleavage is hindered, perturbing the conformation transition from zymogen to enzyme. The crystal structure of FXa shows that this disulfide bond is solvent accessible, indicating that its stability might be subject to the oxidation/reduction balance. As demonstrated with FX p.Cys27Ser here, Cys22-Cys27 disulfide bond may modulate FX clotting activity, with reduced FX pertaining less pro-coagulant activity.
Aim This article evaluates the preventive effects of rivaroxaban versus aspirin on venous thromboembolism (VTE) through meta-analysis of recent randomized controlled trials (RCTs). Methods RCTs were retrieved from medical literature databases. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated to compare the primary and safety endpoints. Results In total, 9 trials (11 trial comparisons) were retrieved which contained 7,656 patients. Among these patients, 4,383 patients (57.2%) received rivaroxaban, whereas 3,273 patients (42.8%) received aspirin. Compared with aspirin, rivaroxaban significantly reduced VTE (1.3% vs. 3.5%) (RR: 0.36, 95% CI, 0.26-0.48, I (2) = 27.9%), but significantly increased nonmajor bleeding (11.5% vs. 7.5%) (RR: 1.28, 95% CI, 1.13-1.44, I (2) = 38.6%). There were no significant differences in the all-cause mortality (0.3% vs. 0.3%) (RR: 0.75, 95% CI, 0.35-1.61, I (2) = 32.0%) and major bleeding (0.3% vs. 0.4%) (RR: 0.81, 95% CI, 0.42-1.55, I (2) = 33.7%) between the two groups. Conclusion This meta-analysis indicated that rivaroxaban can significantly reduce the incidence of VTE when compared with aspirin. The preventive effect of rivaroxaban on VTE was more potent than that of aspirin. However, rivaroxaban had some negative side effects to patients such as nonmajor bleeding compared to aspirin.