Aspirin for prevention and treatment of venous thromboembolism

Tea Consumption, Milk or Sweeteners Addition, Genetic Variation in Caffeine Metabolism, and Incident Venous Thromboembolism

OBJECTIVE

 The association between tea consumption and venous thromboembolism (VTE) remains unknown. We aimed to evaluate the association between tea consumption with different additives (milk and/or sweeteners) and incident VTE, and the modifying effects of genetic variation in caffeine metabolism on the association.

METHODS

 A total of 190,189 participants with complete dietary information and free of VTE at baseline in the UK Biobank were included. The primary outcome was incident VTE, including incident deep vein thrombosis and pulmonary embolism.

RESULTS

 During a median follow-up of 12.1 years, 4,485 (2.4%) participants developed incident VTE. Compared with non-tea drinkers, tea drinkers who added neither milk nor sweeteners (hazard ratio [HR]: 0.85; 95% confidence interval [95% CI]: 0.76-0.94), only milk (HR: 0.86; 95% CI: 0.80-0.93), and both milk and sweeteners to their tea (HR: 0.90; 95% CI: 0.81-0.99) had a lower risk of VTE, while those who added only sweeteners to their tea did not (HR: 0.94; 95% CI: 0.75-1.17). Moreover, there was an L-shaped relationship between tea consumption and incident VTE among tea drinkers who added neither milk nor sweeteners, only milk, and both milk and sweeteners to their tea, respectively. However, a nonsignificant association was found among tea drinkers who added only sweeteners to their tea. Genetic variation in caffeine metabolism did not significantly modify the association (p-interaction = 0.659).

CONCLUSION

 Drinking unsweetened tea, with or without added milk, was associated with a lower risk of VTE. However, there was no significant association between drinking tea with sweeteners and incident VTE.

An Effective Protocol for Perioperative Venous Thromboembolism Prophylaxis in DIEP Flap Breast Reconstruction: A Single Institution Retrospective Review

Background

Deep inferior epigastric artery perforator (DIEP) free flap breast reconstruction is one of the most highly used procedures for autologous breast reconstruction. Many venous thromboembolism (VTE) risk assessment models have been proposed in breast reconstructive surgery, including the widely used Caprini score. However, a paucity of data suggests an effective standardized VTE protocol. The purpose of this study was to determine the rate of VTE in our DIEP flap patients who were treated with this protocol.

Methods

A retrospective single-center review of DIEP flap breast reconstruction from 2016 to 2021 was performed. Data were collected on 554 patients and 893 flaps including demographics, intraoperative and perioperative details, and postoperative course. Patients who were not treated with our standard protocol were excluded. Data were analyzed with alpha = 0.05.

Results

The average age was 50.4 ± 9.9 years, and the total follow-up time was 16.9 ± 12.6 months. The average body mass index for the cohort was 30.1 ± 5.2. During the 90 postoperative days, the mean length of hospital stay was 4.3 days. There were six cases of postoperative VTE: five patients presented with pulmonary embolism (0.9%) and one patient (0.2%) had deep venous thrombosis with an overall VTE prevalence of 1.1%. No specific single factor could be attributed to VTE occurrence.

Conclusions

Using our standardized VTE prophylaxis protocol, our institution was effective at keeping VTE rates low. Additional studies would be beneficial to determine optimal VTE prophylaxis protocols in higher-risk patients, such as those with known clotting disorders.

Discovery and verification of Q-markers for promoting blood circulation and removing stasis of raw and wine-steamed Vaccaria segetalis based on pharmacological evaluation combined with chemometrics

ETHNOPHARMACOLOGICAL RELEVANCE

Dried and mature seeds of Vaccaria segetalis (Neck.) Garcke ex Asch. (VS) are known for their therapeutic effects, as they stimulate blood circulation, promote menstruation and diuresis and eliminate gonorrhoea. However, due to its hard shell, the dissolution of its active ingredients is often improved by steaming and frying in clinical applications. Among the processed products, wine-steamed Vaccaria segetalis (WVS) is one of the commonly used ones. Numerous historical records have shown that wine steaming can enhance the efficacy of drugs to promote blood circulation and remove blood stasis. However, the differences in the efficacy of VS and WVS in promoting blood circulation and removing blood stasis have not been thoroughly studied, and the possible reasons for these differences have not been reported.

AIM OF THE STUDY

The objective of this study was to identify quality markers (Q-markers) that could differentiate the efficacy of promoting blood circulation and removing blood stasis of VS and WVS, which could serve as a basis for the rational application of VS and WVS in clinical settings.

MATERIALS AND METHODS

A pharmacodynamic comparison between the water extracts of VS and WVS was carried out based on a mouse acute blood stasis model (ABS) and thrombus zebrafish model. The potential bioactive substances of WVS were screened by investigating the correlation between common peaks identified for 10 batches of WVS by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS) and their rate of thrombosis inhibition in zebrafish. Furthermore, multivariate statistical analysis of chemical components between VS and WVS was conducted to speculate the Q-markers combined with the results of the bioactive components. Based on the efficacy verification of Q-markers, the content of Q-markers in 10 batches of WVS was evaluated.

RESULTS

The results of efficacy comparison assays demonstrated that the efficacy of WVS was more prominent than VS at the same dose. Five components were screened as effective components of WVS for promoting blood circulation and removing blood stasis by correlation analysis. Furthermore, a total of 24 common ingredients were identified in VS and WVS extracts, and 9 of them showed increased dissolution rate after wine steaming, including 4 active ingredients, Hypaphorine, Vaccarin, Saponarin, and Isovitexin-2″-O-arabinoside, which were screened out by correlation analysis. The monomer test suggested that these 4 components could activate blood circulation and remove blood stasis in a dose-dependent manner. Consequently, Hypaphorine, Vaccarin, Saponarin, and Isovitexin-2″-O-arabinoside were selected as Q-markers to distinguish between VS and WVS. The content determination showed that the total contents of 4 Q-markers of WVS from 10 batches with different origins ranged from 0.478% to 0.716%.

CONCLUSIONS

This study compared the efficacy of VS and WVS in promoting blood circulation and resolving stasis and revealed Q-markers that reflected the difference in efficacy between them for the first time, which laid the foundation for establishing quality standards for WVS.

The central role of neutrophil extracellular traps (NETs) and by-products in COVID-19 related pulmonary thrombosis

Extracellular trap networks (neutrophil extracellular traps [NETs]) of polymorphonuclear neutrophils are mesh-like substances that prevent the spread of pathogens. They primarily consist of DNA skeletons, histones, granule components, and cytoplasmic proteins. NETs formation requires a certain environment and there are different pathways for NETs production. However, it is still not clear how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) promotes NETs. NETs exert antiinflammatory effects through immune response, while they can also lead to certain adverse outcomes, such as the development of immunothrombosis. Coronavirus disease 2019 (COVID-19) is an inflammatory reaction affecting various organs caused by SARS-CoV-2, especially the lungs. NETs production and disease severity are linked with unique neutrophil clusters by single-cell RNA sequencing. NETs might exert an anti-inflammatory role in the initial stage of lung tissue inflammation. Nevertheless, numerous studies and cases have shown that they can also result in pulmonary thrombosis. There is mounting evidence that NETs are tightly related with COVID-19 pulmonary thrombosis, and many studies on the mechanisms are involved. The role and mechanism of NETs in the development of pulmonary thrombosis will be the main topics of this manuscript. Additionally, we address the potential targeting of NETs in COVID-19 patients.

Aspirin prevents estrogen deficiency-induced bone loss by inhibiting osteoclastogenesis and promoting osteogenesis

BACKGROUND

Aspirin is a commonly used antipyretic, analgesic, and anti-inflammatory drug. Numerous researches have demonstrated that aspirin exerts multiple biological effects on bone metabolism. However, its spatiotemporal roles remain controversial according to the specific therapeutic doses used for different clinical conditions, and the detailed mechanisms have not been fully elucidated. Hence, in the present study, we aimed to identify the dual effects of different aspirin dosages on osteoclastic activity and osteoblastic bone formation in vitro and in vivo.

METHODS

The effects of varying doses of aspirin on osteoclast and osteoblast differentiation were evaluated in vitro. The underlying molecular mechanisms were detected using quantitative real-time polymerase chain reaction, western blotting, and immunofluorescence techniques. An ovariectomized rat osteoporosis model was used to assess the bone-protective effects of aspirin in vivo.

RESULTS

Aspirin dose-dependently suppressed RANKL-induced osteoclasts differentiation and bone resorption in vitro and reduced the expression of osteoclastic marker genes, including TRAP, cathepsin K, and CTR. Further molecular analysis revealed that aspirin impaired the RANKL-induced NF-κB and MAPK signaling pathways and prevented the nuclear translocation of the NF-κB p65 subunit. Low-dose aspirin promoted osteogenic differentiation, whereas these effects were attenuated when high-dose aspirin was administered. Both low and high doses of aspirin prevented bone loss in an ovariectomized rat osteoporosis model in vivo.

CONCLUSION

Aspirin inhibits RANKL-induced osteoclastogenesis and promotes osteogenesis in a dual regulatory manner, thus preventing bone loss in vivo. These data indicate that aspirin has potential applications in the prevention and treatment of osteopenia.

Regulatory Effects of Curcumin on Platelets: An Update and Future Directions

The rhizomatous plant turmeric, which is frequently used as a spice and coloring ingredient, yields curcumin, a bioactive compound. Curcumin inhibits platelet activation and aggregation and improves platelet count. Platelets dysfunction results in several disorders, including inflammation, atherothrombosis, and thromboembolism. Several studies have proved the beneficial role of curcumin on platelets and hence proved it is an important candidate for the treatment of the aforementioned diseases. Moreover, curcumin is also frequently employed as an anti-inflammatory agent in conventional medicine. In arthritic patients, it has been shown to reduce the generation of pro-inflammatory eicosanoids and to reduce edema, morning stiffness, and other symptoms. Curcumin taken orally also reduced rats' acute inflammation brought on by carrageenan. Curcumin has also been proven to prevent atherosclerosis and platelet aggregation, as well as to reduce angiogenesis in adipose tissue. In the cerebral microcirculation, curcumin significantly lowered platelet and leukocyte adhesion. It largely modulated the endothelium to reduce platelet adhesion. Additionally, P-selectin expression and mice survival after cecal ligation and puncture were improved by curcumin, which also altered platelet and leukocyte adhesion and blood-brain barrier dysfunction. Through regulating many processes involved in platelet aggregation, curcuminoids collectively demonstrated detectable antiplatelet activity. Curcuminoids may therefore be able to prevent disorders linked to platelet activation as possible therapeutic agents. This review article proposes to highlight and discuss the regulatory effects of curcumin on platelets.

Venous Thromboembolism and Risk of Cancer in Users of Low-Dose Aspirin: A Danish Population-Based Cohort Study

Background  Aspirin may reduce the risk of cancer, particularly gastrointestinal cancer, and venous thromboembolism (VTE). VTE can be the first symptom of occult cancer, but whether it is also a marker of occult cancer in aspirin users remains unknown. Therefore, we investigated the risk of cancer subsequent to VTE among users of low-dose aspirin.

Methods  We conducted a population-based cohort study using data from Danish health registries for the years 2001 to 2018. We identified all patients with a first-time diagnosis of VTE who also redeemed a prescription for low-dose aspirin (75–150mg) within 90 days prior to the first-time VTE. We categorized aspirin users by the number of prescriptions filled as new users (<5 prescriptions), short-term users (5–19 prescriptions), and long-term users (>19 prescriptions). We computed the absolute cancer risks and standardized incidence ratios (SIRs) for cancer using national cancer incidence rates.

Results  We followed-up 11,759 users of low-dose aspirin with VTE. Long-term users comprised 50% of aspirin users. The 1-year absolute risk of cancer was 6.0% for new users and 6.7% for short-term and long-term users, with corresponding SIRs of 3.3 (95% confidence interval [CI]: 2.8–4.0), 3.2 (95% CI: 2.9–3.7), and 2.8 (95% CI: 2.6–3.2), respectively. After the first year of follow-up, the SIR decreased to 1.2 (95% CI: 1.1–1.4) for new users, 1.1 (95% CI: 1.1–1.3) for short-term users, and 1.1 (95% CI: 1.0–1.2) for long-term users.

Conclusion  VTE may be a harbinger of cancer, even in users of low-dose aspirin, regardless of duration of use.

Prolonged Venous Thromboembolism Prophylaxis May Not Be Necessary for DIEP Flap Breast Reconstruction: A Tertiary Center's 10-Year Experience

BACKGROUND

 Based on the 2005 Caprini Risk Assessment Model for venous thromboembolism, the American Society of Plastic Surgeons prevention guidelines would result in prolonged chemoprophylaxis (1 week or more) for the majority of patients undergoing deep inferior epigastric perforator flap breast reconstruction. We aim to assess the necessity of prolonged prophylaxis by describing our institutional experience in thromboembolism prevention and evaluating the incidence of symptomatic VTE in our patient cohort.

METHODS

 Women who underwent DIEP flap reconstruction from August 2011 to March 2020 at a tertiary care center were included. Charts were retrospectively reviewed for patient characteristics, VTE prophylaxis regimens, and development of deep vein thrombosis and pulmonary embolism within 60 days of surgery. Caprini scores were calculated for all patients.

RESULTS

 Out of the 249 patients included in the study, 245 patients received chemoprophylaxis only during hospitalization, while four patients additionally received anticoagulant for at least 2 weeks after discharge for prophylactic or therapeutic indications. The cohort's average Caprini score was 6.0, with 72.7% of scores between 3 and 6 and 26.5% at 7 or higher. One patient (0.4%), who scored a 7 and received prophylaxis only while hospitalized, developed deep vein thrombosis. There were no cases of pulmonary embolism. There was no significant difference in VTE rate between patients who received chemoprophylaxis consistent with ASPS guidelines and those who did not (p = 1.000).

CONCLUSION

 Despite our limited chemoprophylaxis use in DIEP flap patients, our VTE incidence is low. This current work suggests that the blanket application of prolonged prophylaxis is not warranted, and it further serves as impetus to re-evaluate the 2005 Caprini RAM in this patient population.

Neutrophil Extracellular Traps (NETs) and Covid-19: A new frontiers for therapeutic modality

Coronavirus disease 2019 (Covid-19) is a worldwide infectious disease caused by severe acute respiratory coronavirus 2 (SARS-CoV-2). In severe SARS-CoV-2 infection, there is severe inflammatory reactions due to neutrophil recruitments and infiltration in the different organs with the formation of neutrophil extracellular traps (NETs), which involved various complications of SARS-CoV-2 infection. Therefore, the objective of the present review was to explore the potential role of NETs in the pathogenesis of SARS-CoV-2 infection and to identify the targeting drugs against NETs in Covid-19 patients. Different enzyme types are involved in the formation of NETs, such as neutrophil elastase (NE), which degrades nuclear protein and release histones, peptidyl arginine deiminase type 4 (PADA4), which releases chromosomal DNA and gasdermin D, which creates pores in the NTs cell membrane that facilitating expulsion of NT contents. Despite of the beneficial effects of NETs in controlling of invading pathogens, sustained formations of NETs during respiratory viral infections are associated with collateral tissue injury. Excessive development of NETs in SARS-CoV-2 infection is linked with the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) due to creation of the NETs-IL-1β loop. Also, aberrant NTs activation alone or through NETs formation may augment SARS-CoV-2-induced cytokine storm (CS) and macrophage activation syndrome (MAS) in patients with severe Covid-19. Furthermore, NETs formation in SARS-CoV-2 infection is associated with immuno-thrombosis and the development of ALI/ARDS. Therefore, anti-NETs therapy of natural or synthetic sources may mitigate SARS-CoV-2 infection-induced exaggerated immune response, hyperinflammation, immuno-thrombosis, and other complications.

Involvement of Inflammation in Venous Thromboembolic Disease: An Update in the Age of COVID-19

The inflammatory process is strongly involved in the pathophysiology of venous thromboembolism (VTE) and has a significant role in disease prediction. Inflammation most probably represents a common denominator through which classical and nonclassical risk factors stimulate thrombotic process. Inflammation of the venous wall promotes the release of tissue factor, inhibits the release of anticoagulant factors, and hampers endogenous fibrinolysis. Systemic inflammatory response also inhibits restoration of blood flow in the occluded vessel. Recent studies indicate that increased inflammatory response ("cytokine storm") is related to prothrombotic state and thromboembolic events in patients with coronavirus disease 2019 (COVID-19). The growing evidence of involvement of inflammation in the pathogenesis of VTE indicates the importance of anti-inflammatory treatment and prevention of VTE. While aspirin was shown to be effective in prevention of recurrent venous thrombosis after treatment with anticoagulant drugs, some other anti-inflammatory drugs like nonsteroidal anti-inflammatory agents may have prothrombotic effect, thus potentially increasing the risk of VTE. Recently, new specific anti-inflammatory drug inhibitors of inflammatory markers that have been shown to be involved in the pathogenesis of VTE are being searched. As thrombogenesis is based on activation of coagulation provoked by inflammation, then prevention and treatment of VTE should include both anticoagulant and anti-inflammatory agents. Combined treatment is related to increased risk of bleeding complications, therefore subtherapeutic doses of both drugs should be used to improve the efficacy of management of VTE without increasing the risk of bleeding.

Chronic Application of Low-Dose Aspirin Affects Multiple Parameters of Three Blood Cellular Types and Antithrombin Activity: A 1:1:1 Propensity Score Matching Analysis

ABSTRACT

The mechanisms of aspirin antithrombotic actions have not been fully elucidated. We re-analyzed the data from the project Aspirin Resistance in Patients with Ischemic Atherothrombotic Diseases from April 2008 to June 2010. A total of 530 subjects were classified into 3 groups, including 40 patients without aspirin use, 24 patients taking 25-50 mg/d aspirin, and 466 patients taking 75-100 mg/d aspirin over 1 month. By 1:1:1 propensity score matching adjusting 15 primary clinical covariates, 51 patients (n = 17 per group) comprised the final sample. Hemostasis-related parameters and high platelet reactivity as measured by arachidonic acid-induced and adenosine diphosphate-induced light transmission aggregometry were compared in the 3 groups. A dose-dependent relationship was observed between aspirin and decreased high platelet reactivity incidence (PAA < 0.001, PADP < 0.01, respectively), decreased monocyte ratio (P = 0.052), increased antithrombin activity (P < 0.001), and increased platelet distribution width (P < 0.05). Aspirin at 25-50 mg/d is related to the lowest red blood cell (RBC) count, whereas 75-100 mg/d aspirin showed the highest RBC count among the 3 groups (4.52 ± 0.35 × 1012/L vs. 4.35 ± 0.57 × 1012/L vs. 4.80 ± 0.59 × 1012/L, P = 0.046). Our finding demonstrated that aspirin exerts its antithrombotic effects at least by antiplatelet function, enhancing antithrombin activity and suppressing monocytes in vivo. In addition, 3 blood cell types, namely RBCs, monocytes, and platelets, are involved in the aspirin antithrombotic mechanism. The cellular response to aspirin partially enhances the antithrombotic effects while partially inhibiting the effects.

Overall and abdominal obesity in relation to venous thromboembolism

BACKGROUND

Abdominal obesity has been shown to be a superior measure over overall obesity for detecting cardiovascular risk.

OBJECTIVE

We conducted this study to compare the effects of overall and abdominal obesity on venous thromboembolism (VTE) and to calculate population attributable fraction for obesity for VTE.

METHODS

Body mass index (BMI) and waist circumference (WC) were used to represent overall and abdominal obesity, respectively. In the cohort study, we included 74317 Swedish adults with anthropometric measures in 1997 and of whom 4332 were diagnosed with VTE until the end of 2017. A Mendelian randomization study was conducted to investigate causal associations of BMI, WC, and WC adjusted for BMI with VTE using data from FinnGen and UK Biobank study. Population attributable fraction was calculated for overall and abdominal obesity for VTE.

RESULTS

In the cohort study, there were dose-response associations of BMI and WC with VTE. The association between BMI and VTE was attenuated largely after adjusting for WC. Among individuals with normal BMI, participants with substantially increased WC had 53% higher (hazard ratio 1.53; 95% confidence interval, 1.28, 1.81) risk of VTE compared to those with normal WC. The causality of the association of WC adjusted for BMI with VTE was confirmed in Mendelian randomization analysis. The estimated population-attributable risk due to elevated BMI and WC were 12.4% (8.4%, 16.5%) and 23.7% (18.1%, 29.4%), respectively.

CONCLUSIONS

WC might be a preferable indicator linking obesity to VTE. A large proportion of VTE cases can be prevented if the population maintained a healthy BMI and WC.

Interaction Between Low-Dose Aspirin and Nonsteroidal Anti-Inflammatory Drugs Can Compromise Aspirin's Efficacy in Preventing Venous Thrombosis Following Total Joint Arthroplasty

Total joint arthroplasty is a rapid recovery procedure with patients optimized quickly in preparation for discharge. Two significant postoperative goals are effective pain management and prevention of postoperative venous thromboembolism (VTE). Low-risk patients receive aspirin 81 mg twice daily for VTE prophylaxis; this dosing regimen has been reduced over the past few years from 325 mg to 162 mg to 81 mg twice daily. Unless contraindications exist, all patients receive multimodal pain management that includes the use of celecoxib or meloxicam. Upon reduction of the aspirin dose to 81 mg twice daily, we rapidly identified 2 patients who developed a pulmonary embolus when celecoxib or meloxicam was administered concurrently with aspirin. The interaction between nonsteroidal anti-inflammatory drugs (NSAIDs) and low-dose aspirin varies among the different NSAIDs. It is also highly dependent on numerous factors, including time of administration, dose of aspirin, and both pharmacodynamics and dose of the NSAID. Real-world outcomes of concomitant administration of NSAIDs with low-dose aspirin led to increased incidence of VTE, possibly due to competitive inhibition of aspirin at platelet receptor sites. This interaction was mitigated by altering the administration times of both agents.

Metabolites in a mouse cancer model enhance venous thrombogenicity through the aryl hydrocarbon receptor-tissue factor axis

Patients with malignancy are at 4- to 7-fold higher risk of venous thromboembolism (VTE), a potentially fatal, yet preventable complication. Although general mechanisms of thrombosis are enhanced in these patients, malignancy-specific triggers and their therapeutic implication remain poorly understood. Here we examined a colon cancer-specific VTE model and probed a set of metabolites with prothrombotic propensity in the inferior vena cava (IVC) ligation model. Athymic mice injected with human colon adenocarcinoma cells exhibited significantly higher IVC clot weights, a biological readout of venous thrombogenicity, compared with the control mice. Targeted metabolomics analysis of plasma of mice revealed an increase in the blood levels of kynurenine and indoxyl sulfate (tryptophan metabolites) in xenograft-bearing mice, which correlated positively with the increase in the IVC clot size. These metabolites are ligands of aryl hydrocarbon receptor (AHR) signaling. Accordingly, plasma from the xenograft-bearing mice activated the AHR pathway and augmented tissue factor (TF) and plasminogen activator inhibitor 1 (PAI-1) levels in venous endothelial cells in an AHR-dependent manner. Consistent with these findings, the endothelium from the IVC of xenograft-bearing animals revealed nuclear AHR and upregulated TF and PAI-1 expression, telltale signs of an activated AHR-TF/PAI-1 axis. Importantly, pharmacological inhibition of AHR activity suppressed TF and PAI-1 expression in endothelial cells of the IVC and reduced clot weights in both kynurenine-injected and xenograft-bearing mice. Together, these data show dysregulated tryptophan metabolites in a mouse cancer model, and they reveal a novel link between these metabolites and the control of the AHR-TF/PAI-1 axis and VTE in cancer.

Management of a decompensated acute-on-chronic intracranial venous sinus thrombosis

A 34-year-old female patient presented during the 10th week of her second gravidity with headache, nausea and vomiting 2 weeks before admission. Her medical history was remarkable for a heterozygous factor V Leiden mutation, elevated lipoprotein A, and a cerebral venous thrombosis (CVT) after oral contraceptive intake 15 years before. Magnetic resonance imaging (MRI) suggested acute and massive intracranial sinus thrombosis. Despite full-dose anticoagulation, the patient deteriorated clinically and eventually became comatose. Now, MRI/magnetic resonance angiography revealed vasogenic edema of both thalami, of the left frontal lobe, and of the head of the caudate nucleus, with venous stasis and frontal petechial hemorrhage. She was referred for endovascular treatment. Diagnostic angiography confirmed a complete superficial and deep venous sinus occlusion. Endovascular access to the straight and superior sagittal sinus was possible, but neither rheolysis nor balloon angioplasty resulted in recanalization of the venous sinuses. Monitored heparinization was continued and antiaggregation was initiated. The patient remained comatose for another 5 days and MRI showed progress of the cytotoxic edema. On day 6, infusion of eptifibatide at body-weight-adapted dosage was started. The following day, the patient improved and slowly regained consciousness. MRI confirmed regression of the edema. The eptifibatide infusion was continued for a total of 14 days. Thereafter two doses of 180 mg ticagrelor per os (PO) daily were started. The patient remained on acetylsalicylic acid (ASA), ticagrelor, and enoxaparin on an unchanged dosage regimen. She was discharged home 26 days after the endovascular treatment without serious neurological deficit, with the pregnancy intact. At the 30th week of pregnancy the dosage of ASA was reduced to 300 mg once PO daily. Cesarian delivery was carried out at the 38th week of pregnancy. The newborn was completely healthy. Ultima ratio therapeutic options for severe intracranial venous sinus thrombosis refractory to anticoagulation are discussed, with an emphasis on platelet-function inhibition.

Characterization of active anticoagulant fraction and a fibrin(ogen)olytic serine protease from leaves of Clerodendrum colebrookianum, a traditional ethno-medicinal plant used to reduce hypertension

ETHNOPHARMACOLOGICAL RELEVANCE

Cardiovascular diseases are the major cause of mortality and morbidity, causing over 17.9 million deaths a year worldwide. Currently used therapy is often having side effects and expensive, dietary interventions and alternative medicines are required. Clerodendrum colebrookianum has been used to treat cardiac hypertension but anticoagulant potency was not evaluated.

AIM OF THE STUDY

To characterize an active anticoagulant fraction (AAFCC) and a 30 kDa fibrin(ogen)olytic serine protease (clerofibrase) isolated from aqueous leave extract of C. colebrookianum.

MATERIALS AND METHODS

AAFCC/clerofibrase was subjected to extensive biochemical and pharmacological characterization including LC-MS/MS, amino acid compositional and GC-MS analyses. Interaction between clerofibrase with fibrinogen was studied by spectrofluorometric analysis. In vitro thrombolytic, antiplatelet and cytotoxicity assay were performed. In vivo toxicity, anticoagulant, defibrinogen and antithrombotic activities were determined on Swiss albino mice.

RESULTS

The in vitro anticoagulant activity of AAFCC was found to be superior to heparin and clerofibrase and comparable to Nattokinase and warfarin. The proteomics and amino acid composition analyses suggest that clerofibrase is a previously uncharacterized novel plant protease capable of degrading the -αβ chains of fibrinogen/fibrin. AAFCC/clerofibrase exerts their anticoagulant action via fibrinogenolytic activity and partially by antiplatelet activity albeit they have no effect on thrombin and FXa inhibition. The spectrofluorometric analysis revealed the binding of clerofibrase to fibrinogen but not to thrombin and FXa. The phytochemical constituents and bioactive components of AAFCC were characterized by biochemical, and GC-MS analyses. The AAFCC and clerofibrase inhibited collagen/ADP-induced mammalian platelet aggregation, showed in vitro thrombolytic activity, and non-cytotoxic to mammalian cells. The AAFCC showed and dose-dependent in vivo plasma defibrinogenating and anticoagulant activities and inhibited k-carrageen-induced thrombus formation in the tails of mice.

CONCLUSION

The potent in vivo anticoagulant and antithrombotic effects of AAFCC suggests its pharmacological significance as herbal anticoagulant drug for the prevention and/or treatment of hyperfibrinogenemia- and thrombosis associated cardiovascular disorders.

Venous thromboembolism in plastic surgery: the current state of evidence in risk assessment and chemoprophylactic options

The application of venous thromboembolism (VTE) prophylaxis has been the topic of intense debate in plastic surgery. The overall incidence of VTE is low in plastic surgery patients as compared to other surgical subspecialties but may be higher in the inpatient rather than outpatient plastic surgery populations. The Caprini Risk Assessment Model is the most highly studied and validated tool to assess VTE risk in plastic surgery patients. However, the Caprini model lacks procedure-specific risk assessment and patient-specific risk factor calculations. Due to these limitations, such as the low incidence and the heterogeneous nature of the specialty, trials lacked the power to capture proof of benefit, except in the highest-risk inpatient population. The emerging use of aspirin and novel oral anticoagulants may provide an alternative, as noninferiority in terms of efficacy and safety has been demonstrated in other fields. In this review, the authors intend to summarize the current state of evidence for prevention and explore the modalities available for prophylaxis, including novel oral anticoagulants.

iTRAQ-based proteomic analysis of human umbilical vein endothelial cells with platelet endothelial aggregation receptor-1 knockdown

The disorders of hemostasis and coagulation were believed to be the main contributors to the pathogenesis of pulmonary thromboembolism (PTE), and platelets are the basic factors regulating hemostasis and coagulation and play important roles in the process of thrombosis. This study investigated the proteome of human umbilical vein endothelial cells (HUVECs) with platelet endothelial aggregation receptor-1 (PEAR1) knockdown using the isobaric tags for relative and absolute quantitation (iTRAQ) method and analyzed the role of differential abundance proteins (DAPs) in the regulation of platelets aggregation. Our results showed that the conditioned media-culturing HUVECs with PEAR1 knockdown partially suppressed the adenosine diphosphate (ADP)-induced platelet aggregation. The proteomics analysis was performed by using the iTRAQ technique, and a total of 215 DAPs (124 protein was upregulated and 91 protein were downregulated) were identified. The Gene Ontology (GO) enrichment analysis showed that proteins related to platelet α granule, adenosine triphosphate metabolic process, and endocytosis were significantly enriched. Further, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis also identified the significant enrichment of endocytosis-related pathways. The real-time polymerase chain reaction assay confirmed that the expression of P2Y₁₂ , mitochondrial carrier 2, NADH dehydrogenase (ubiquinone) iron-sulfur protein 3, and ubiquinol-cytochrome c reductase hinge protein are significantly downregulated in the HUVECs with PEAR1 knockdown. In conclusion, our in vitro results implicated that DAPs induced by PEAR1 knockdown might contribute to the platelet aggregation. Proteomic studies by employing GO enrichment and KEGG pathway analysis suggested that the potential effects of DAPs on platelet aggregation may be linked to the balance of ADP synthesis or degradation in mitochondria.

Risk factors for linezolid-induced thrombocytopenia in patients without haemato-oncologic diseases

This study aimed to describe the occurrence and to evaluate the predictive factors of thrombocytopenia caused by parenteral linezolid in hospitalised patients without haemato-oncologic diseases. Using electronic medical records, a retrospective safety evaluation was performed among all hospitalised adult patients who received parenteral linezolid therapy between January 2005 and June 2016. Of all identified 264 patients with an average age of 63.4 (SD 15.8) years, thrombocytopenia occurred at a rate of 29.2% after an average of 11.2 (SD 7.4) days of the initiation of linezolid therapy. Significant predictive factors for thrombocytopenia included the duration of linezolid therapy longer than or equal to 7 days (adjusted odds ratios [ORs] 7.25, 19.51 and 28.80; 95% confidence intervals [CIs] 1.92-27.38, 4.76-79.95 and 6.48-127.92 for 7-13 days, 14-20 days and ≥21 days, respectively; P < 0.01 for all values), baseline platelet count <150 × 10³ /mm³ (adjusted OR, 5.08; 95% CI, 2.06-12.55; P < 0.001), creatinine clearance <30 mL/min (adjusted OR, 4.19; 95% CI, 1.59-11.06; P = 0.004) and concurrent low-dose aspirin therapy (adjusted OR, 2.99; 95% CI, 1.26-7.08; P = 0.013). Baseline platelet count less than 150 × 10³ /mm³ was an independent predictor of early-onset (≤6 days) thrombocytopenia (adjusted OR, 5.07; 95% CI, 1.46-17.58; P = 0.011). Closer monitoring of platelet count is required in patients who receive parenteral linezolid therapy for 7 days or more, and have low baseline platelet counts or impaired renal function.

Acute pulmonary embolism and deep vein thrombosis secondary to idiopathic hypereosinophilic syndrome

Acute pulmonary embolism (PE) is a most dangerous complication that needs prompt treatment to reduce potentially death. There are many well-known prognostic factors indicate the morbidity and mortality in various thromboembolic events. Persistent eosinophilia in peripheral blood can lead to tissue infiltration and even organ damage, but the urgent event of thromboembolism in pulmonary provoked by eosinophil eosinophilia in idiopathic hypereosinophilic syndrome (HES) is relative an unusual presentation. In this paper, we present two cases of patients with multiple PE and deep vein thrombosis secondary to the idiopathic HES. Patients were all treated using anticoagulant therapy and corticosteroids successfully. Accordingly, eosinophilia is another risk and precipitating factor of pulmonary thromboembolism. It is necessary for physicians to make a diagnosis in hypereosinophilia as soon as possible for proper prognosis and in case of further thromboembolic events and prevent end-organ damage.

Association between aspirin use and deep venous thrombosis in mechanically ventilated ICU patients

Deep venous thrombosis (DVT) is common in intensive care unit (ICU) patients. It is often silent and may be complicated by pulmonary embolism and death. Thromboprophylaxis with heparin does not always prevent venous thromboembolism (VTE). Aspirin (ASA) reduces the risk of VTE in surgical and high-risk medical patients but it is unknown if ASA may prevent DVT in mechanically ventilated ICU patients. We performed a retrospective chart review of critically ill patients who received mechanical ventilation for >72 h and underwent venous ultrasonography for suspected DVT between Jan 2012 and Dec 2013. We excluded patients who were on therapeutic doses of anticoagulation or had coagulopathy. We used multivariable logistic regression to evaluate association between aspirin use and DVT during hospitalization. There were 193 patients. The mean ± SD age was 58 ± 15.7 years. Half were male. DVT was found in 49 (25.4%). DVT was found in the first 15 days of hospitalization in 67.3% of the patients. The majority (82.8%) received thromboprophylaxis with unfractionated or low molecular weight heparin. Fifty-six (29%) were on ASA. On multivariable regression analysis, ASA use was associated with a significant reduction in the odds of finding DVT (OR 0.39, 95% CI 0.16-0.94; p = 0.036). DVT is common in mechanically ventilated ICU patients despite the use of thromboprophylaxis. Aspirin may prevent DVT in such patients.

Curcumin, hemostasis, thrombosis, and coagulation

Atherothrombotic cardiovascular disease is a major cause of mortality throughout the world. Platelet activation and aggregation play a central role in hemostasis and thrombosis. Herbal medicines have been traditionally used in the management of cardiovascular disease and can help in modifying its progression, particularly in hemostasis and the coagulation process, as well as altering platelet function tests and some coagulation parameters. Curcumin is a polyphenol derived from the Curcuma longa plant and has been used extensively in complementary and alternative medicine, as it is nontoxic and safe with various therapeutic properties. Modern scientific research has demonstrated its anti-inflammatory, antioxidant, anti-carcinogenic, antithrombotic, and cardiovascular protective effects. The present study reviewed previous studies in the literature, which support the positive activity of curcumin in hemostasis, anticoagulation, and fibrinolysis. We also presented molecular mechanisms associated with the antiplatelet and anticoagulant activities of curcumin and potential implications for the treatment of cardiovascular disease.

Deep Venous Thrombosis

Deep venous thrombosis (DVT) is a frequently encountered condition that is often diagnosed and treated in the outpatient setting. Risk stratification is helpful and recommended in the evaluation of DVT. An evidence-based diagnostic approach is discussed here. Once diagnosed, the mainstay of DVT treatment is anticoagulation. The specific type and duration of anticoagulation depend upon the suspected etiology of the venous thromboembolism, as well as risks of bleeding and other patient comorbidities. Both specific details and a standardized approach to this vast treatment landscape are presented.

Platelet activation by ADP is increased in selected patients with anterior ischemic optic neuropathy or retinal vein occlusion

To investigate whether adenosine diphosphate (ADP)-induced platelet hyperaggregability is associated with nonarteritic anterior ischemic optic neuropathy (NAION) or retinal vein occlusion (RVO). We retrospectively reviewed thrombophilia screening data of patients with NAION or RVO without a history of arterial hypertension, diabetes mellitus, hyperlipidemia, obesity, and cigarette abuse. Patients with a positive family history for thromboembolism were not excluded. Platelet aggregation (area under the curve, AUC) after induction of 0.5, 1.0, and 2.0 µmol of ADP was estimated in 25 NAION and RVO patients and compared with 25 healthy controls. We observed significantly greater platelet aggregation post 0.5 (P = 0.002) and 1.0 (P = 0.008) µmol of ADP among NAION and RVO patients compared with healthy controls. Platelet hyperaggregability was significantly more prevalent in patients than in controls (56% vs. 8%; P = 0.0006). Our results suggest that in NAION and RVO patients without a history of arterial hypertension, diabetes mellitus, hyperlipidemia, obesity, and cigarette abuse, platelets are significantly hyperreactive after induction of very low concentrations of ADP when compared with healthy individuals. This hyperreactivity is particularly evident in patients with a family history of thromboembolism.

Localization of Short-Chain Polyphosphate Enhances its Ability to Clot Flowing Blood Plasma

Short-chain polyphosphate (polyP) is released from platelets upon platelet activation, but it is not clear if it contributes to thrombosis. PolyP has increased propensity to clot blood with increased polymer length and when localized onto particles, but it is unknown whether spatial localization of short-chain polyP can accelerate clotting of flowing blood. Here, numerical simulations predicted the effect of localization of polyP on clotting under flow, and this was tested in vitro using microfluidics. Synthetic polyP was more effective at triggering clotting of flowing blood plasma when localized on a surface than when solubilized in solution or when localized as nanoparticles, accelerating clotting at 10-200 fold lower concentrations, particularly at low to sub-physiological shear rates typical of where thrombosis occurs in large veins or valves. Thus, sub-micromolar concentrations of short-chain polyP can accelerate clotting of flowing blood plasma under flow at low to sub-physiological shear rates. However, a physiological mechanism for the localization of polyP to platelet or vascular surfaces remains unknown.

Aspirin in pancreatic cancer: chemopreventive effects and therapeutic potentials

Pancreatic cancer is one of the most aggressive malignancies with dismal prognosis. Recently, aspirin has been found to be an effective chemopreventive agent for many solid tumors. However, the function of aspirin use in pancreatic cancer largely remains unknown. We herein argued that aspirin could also lower the risk of pancreatic cancer. Importantly, aspirin assumes pleiotropic effects by targeting multiple molecules. It could further target the unique tumor biology of pancreatic cancer and modify the cancer microenvironment, thus showing remarkable therapeutic potentials. Besides, aspirin could reverse the chemoradiation resistance by repressing tumor repopulation and exert synergistic potentials with metformin on pancreatic cancer chemoprevention. Moreover, aspirin secondarily benefits pancreatic cancer patients through modestly reducing cancer pain and the risk of venous thromboembolism. Furthermore, new aspirin derivatives and delivery systems might help to improve risk-to-benefit ratio. In brief, aspirin is a promising chemopreventive agent and exerts significant therapeutic potentials in pancreatic cancer.

Platelet abnormalities in nephrotic syndrome

Nephrotic syndrome (NS) is a common kidney disease associated with a significantly increased risk of thrombotic events. Alterations in plasma levels of pro- and anti-coagulant factors are involved in the pathophysiology of venous thrombosis in NS. However, the fact that the risk of both venous and arterial thrombosis is elevated in NS points to an additional role for blood platelets. Increased platelet counts and platelet hyperactivity have been observed in nephrotic children. Platelet hyperaggregability, increased release of active substances, and elevated surface expression of activation-dependent platelet markers have been documented. The mechanisms underlying those platelet alterations are multifactorial and are probably due to changes in plasma levels of platelet-interfering proteins and lipid changes, as a consequence of nephrosis. The causal relationship between platelet alterations seen in NS and the occurrence of thromboembolic phenomena remains unclear. Moreover, the efficiency of prophylactic treatment using antiplatelet agents for the prevention of thrombotic complications in nephrotic patients is also unknown. Thus, antiplatelet medication is currently not generally recommended for routine prophylactic therapy.

Platelets are versatile cells: New discoveries in hemostasis, thrombosis, immune responses, tumor metastasis and beyond

Platelets are small anucleate blood cells generated from megakaryocytes in the bone marrow and cleared in the reticuloendothelial system. At the site of vascular injury, platelet adhesion, activation and aggregation constitute the first wave of hemostasis. Blood coagulation, which is initiated by the intrinsic or extrinsic coagulation cascades, is the second wave of hemostasis. Activated platelets can also provide negatively-charged surfaces that harbor coagulation factors and markedly potentiate cell-based thrombin generation. Recently, deposition of plasma fibronectin, and likely other plasma proteins, onto the injured vessel wall has been identified as a new "protein wave of hemostasis" that may occur even earlier than the first wave of hemostasis, platelet accumulation. Although no experimental evidence currently exists, it is conceivable that platelets may also contribute to this protein wave of hemostasis by releasing their granule fibronectin and other proteins that may facilitate fibronectin self- and non-self-assembly on the vessel wall. Thus, platelets may contribute to all three waves of hemostasis and are central players in this critical physiological process to prevent bleeding. Low platelet counts in blood caused by enhanced platelet clearance and/or impaired platelet production are usually associated with hemorrhage. Auto- and allo-immune thrombocytopenias such as idiopathic thrombocytopenic purpura and fetal and neonatal alloimmune thrombocytopenia may cause life-threatening bleeding such as intracranial hemorrhage. When triggered under pathological conditions such as rupture of an atherosclerotic plaque, excessive platelet activation and aggregation may result in thrombosis and vessel occlusion. This may lead to myocardial infarction or ischemic stroke, the major causes of mortality and morbidity worldwide. Platelets are also involved in deep vein thrombosis and thromboembolism, another leading cause of mortality. Although fibrinogen has been documented for more than half a century as essential for platelet aggregation, recent studies demonstrated that fibrinogen-independent platelet aggregation occurs in both gene deficient animals and human patients under physiological and pathological conditions (non-anti-coagulated blood). This indicates that other unidentified platelet ligands may play important roles in thrombosis and might be novel antithrombotic targets. In addition to their critical roles in hemostasis and thrombosis, emerging evidence indicates that platelets are versatile cells involved in many other pathophysiological processes such as innate and adaptive immune responses, atherosclerosis, angiogenesis, lymphatic vessel development, liver regeneration and tumor metastasis. This review summarizes the current knowledge of platelet biology, highlights recent advances in the understanding of platelet production and clearance, molecular and cellular events of thrombosis and hemostasis, and introduces the emerging roles of platelets in the immune system, vascular biology and tumorigenesis. The clinical implications of these basic science and translational research findings will also be discussed.

Drug Treatment of Venous Thromboembolism in the Elderly

Half of all patients with acute venous thromboembolism are aged over 70 years; they then face the added hazard of an age-related increase in the incidence of major bleeding. This makes it even more important to weigh the balance of benefit and risk when considering anticoagulant treatment and treatment duration. Traditional treatment with a heparin (usually low molecular weight) followed by a vitamin K antagonist such as warfarin is effective but is often complicated, especially in the elderly. The direct-acting oral anticoagulants (DOACs), i.e. the thrombin inhibitor dabigatran and the factor Xa inhibitors rivaroxaban, apixaban and edoxaban, are given in fixed doses, do not need laboratory monitoring, have fewer drug-drug interactions and are therefore much easier to take. Randomised trials, their meta-analyses and 'real-world' data indicate the DOACs are no less effective than warfarin (are non-inferior) and probably cause less major bleeding (especially intracranial). It seems the relative safety of DOACs extends to age above 65 or 70 years, although bleeding becomes more likely regardless of the chosen anticoagulant. Renal impairment, comorbidities (especially cancer) and interventions are special hazards. Ways to minimise bleeding include patient selection and follow-up, education about venous thromboembolism, anticoagulants, drug interactions, regular checks on adherence and avoiding needlessly prolonged treatment. The relatively short circulating half-lives of DOACs mean that time, local measures and supportive care are the main response to major bleeding. They also simplify the management of invasive interventions. An antidote for dabigatran, idarucizumab, was recently approved by regulators, and a general antidote for factor Xa inhibitors is in advanced development.

Aspirin and multiple sclerosis

Aspirin is widely used to lessen the risks of cardiovascular events. Some studies suggest that patients with multiple sclerosis have an increased risk for some cardiovascular events, for example, venous thromboembolism and perhaps ischemic strokes, raising the possibility that aspirin could lessen these increased risks in this population or subgroups (patients with limited mobility and/or antiphospholipid antibodies). However, aspirin causes a small increased risk of hemorrhagic stroke, which is a concern as it could potentially worsen a compromised blood-brain barrier. Aspirin has the potential to ameliorate the disease process in multiple sclerosis (for example, by limiting some components of inflammation), but aspirin also has the potential to inhibit mitochondrial complex I activity, which is already reduced in multiple sclerosis. In an experimental setting of a cerebral ischemic lesion, aspirin promoted the proliferation and/or differentiation of oligodendrocyte precursors, raising the possibility that aspirin could facilitate remyelination efforts in multiple sclerosis. Other actions by aspirin may lead to small improvements of some symptoms (for example, lessening fatigue). Here we consider potential benefits and risks of aspirin usage by patients with multiple sclerosis.

Perspective: Tyrosine phosphatases as novel targets for antiplatelet therapy

Arterial thrombosis is the primary cause of most cases of myocardial infarction and stroke, the leading causes of death in the developed world. Platelets, highly specialized cells of the circulatory system, are key contributors to thrombotic events. Antiplatelet drugs, which prevent platelets from aggregating, have been very effective in reducing the mortality and morbidity of these conditions. However, approved antiplatelet therapies have adverse side effects, most notably the increased risk of bleeding. Moreover, there remains a considerable incidence of arterial thrombosis in a subset of patients receiving currently available drugs. Thus, there is a pressing medical need for novel antiplatelet agents with a more favorable safety profile and less patient resistance. The discovery of novel antiplatelet targets is the matter of intense ongoing research. Recent findings demonstrate the potential of targeting key signaling molecules, including kinases and phosphatases, to prevent platelet activation and aggregation. Here, we offer perspectives to targeting members of the protein tyrosine phosphatase (PTP) superfamily, a major class of enzymes in signal transduction. We give an overview of previously identified PTPs in platelet signaling, and discuss their potential as antiplatelet drug targets. We also introduce VHR (DUSP3), a PTP that we recently identified as a major player in platelet biology and thrombosis. We review our data on genetic deletion as well as pharmacological inhibition of VHR, providing proof-of-principle for a novel and potentially safer VHR-based antiplatelet therapy.

Natural Products for Antithrombosis

Thrombosis is considered to be closely related to several diseases such as atherosclerosis, ischemic heart disease and stroke, as well as rheumatoid arthritis, hyperuricemia, and various inflammatory conditions. More and more studies have been focused on understanding the mechanism of molecular and cellular basis of thrombus formation as well as preventing thrombosis for the treatment of thrombotic diseases. In reality, there is considerable interest in the role of natural products and their bioactive components in the prevention and treatment of thrombosis related disorders. This paper briefly describes the mechanisms of thrombus formation on three aspects, including coagulation system, platelet activation, and aggregation, and change of blood flow conditions. Furthermore, the natural products for antithrombosis by anticoagulation, antiplatelet aggregation, and fibrinolysis were summarized, respectively.