Antithrombotic drug removal from whole blood using Haemoadsorption with a porous polymer bead sorbent.

AIM: To evaluate the ability of the DrugSorb™-AntiThrombotic Removal (ATR) haemoadsorption device utilizing porous polymer bead sorbent technology to remove three commonly used antithrombotic drugs from whole blood. METHODS AND RESULTS: We evaluated the removal of apixaban, rivaroxaban, and ticagrelor by the DrugSorb-ATR haemoadsorption device in a benchtop clinical scale model using bovine whole blood. Blood spiked at clinically relevant concentrations of an antithrombotic agent was continuously circulated through a 300-mL DrugSorb-ATR haemoadsorption device at a flow rate of 300 mL/min. Drug concentration was monitored over 6 h to evaluate drug removal. Results were compared with a control circuit without the haemoadsorption device. Removal rates at 30, 60, 120, and 360 minutes were: apixaban: 81.5%, 96.3%, 99.3% >99.8%; rivaroxaban: 80.7%, 95.1%, 98.9%, >99.5%; ticagrelor: 62.5%; 75%, 86.6%, >95% (all P <0.0001 vs. control). Blood pH and haematological parameters were not significantly affected by the DrugSorb-ATR haemoadsorption device when compared with the control circuit. CONCLUSION: DrugSorb-ATR efficiently removes apixaban, rivaroxaban, and ticagrelor in a clinical-scale benchtop recirculation circuit with the bulk of removal occurring in the first 60 minutes. The clinical implications of these findings are currently investigated in patients undergoing on-pump cardiothoracic surgery in two US pivotal trials (ClinicalTrials.gov Identifiers: NCT04976530 and NCT05093504).

Rationale and design of the safe and timely antithrombotic removal - ticagrelor (STAR-T) trial: A prospective, multi-center, double-blind, randomized controlled trial evaluating reductions in postoperative bleeding with intraoperative removal of ticagrelor by the drugsorb™-ATR device in patients undergoing cardiothoracic surgery within 48 hours from last ticagrelor dose.

BACKGROUND: Ticagrelor is often administered to patients with acute coronary syndromes. However, when these patients require urgent or emergent cardiothoracic (CT) surgery the presence of ticagrelor significantly increases surgical bleeding. The goal of the current trial is to evaluate the effectiveness and safety of the DrugSorb-ATR hemoadsorption device for the intraoperative removal of ticagrelor to reduce postoperative bleeding in the above patient population. The Safe and Timely Antithrombotic Removal - Ticagrelor (STAR-T) Trial is a multi-center, double-blind, randomized, controlled trial enrolling patients who require cardiothoracic surgery on cardiopulmonary bypass (CPB) within 48 hours of last ticagrelor dose. METHODS: Subjects will be randomized 1:1 to receive either the DrugSorb-ATR device or an identical sham device during CPB. The study will enroll up to 120 subjects at 20 U.S centers, and the primary outcome is the composite of fatal perioperative bleeding, moderate/severe/massive bleeding according to the Universal Definition of Perioperative Bleeding in Cardiac Surgery (UDPB), and 24 hours chest tube drainage. The components of the composite are hierarchically ranked according to clinical significance and the primary analysis will utilize the Win Ratio method. Percent change in ticagrelor levels before and after CPB (drug removal) will be the key secondary endpoint. An independent Clinical Events Committee will adjudicate all clinical endpoints including safety endpoints relating to postoperative thrombotic events. Subjects will be followed through 30 days after the index operation. CONCLUSIONS: The results from STAR-T, if positive, will potentially support FDA market approval for DrugSorb-ATR, and provide a solution to an important unmet clinical need.

Influence of Lipid Excipients on Platelet Function and the Pharmacodynamic Effects of Aspirin.

ABSTRACT: The combination of pharmaceutical lipid excipients with aspirin in a novel liquid oral formulation (Vazalore) limits gastrointestinal toxicity of aspirin. This study was performed to determine whether the lipid excipients influence the pharmacodynamic effects of aspirin and whether the excipients directly affect platelet function. The pharmacodynamic effects of aspirin were assessed over a range of concentrations designed to exert limited to maximal inhibition of cyclooxygenase-1 (COX1) necessary for thromboxane A2 production. Platelet aggregation induced by arachidonic acid and assessed with the use of light transmission aggregometry was used as a direct measure of the inhibition of COX1 by aspirin. Flow cytometry was used to assess the direct effect of excipients on platelet function. Twice the ratio of lipid excipient to aspirin used in the formulation of the novel oral agent was used. Blood was taken from 20 healthy subjects and anticoagulated with trisodium citrate (3.2%, 1:10 vol/vol). Aspirin and excipients were added in vitro and incubated for 10 minutes before performance of light transmission aggregometry and flow cytometry. The excipients did not limit the pharmacodynamic effects of aspirin. When the extent of inhibition of platelet aggregation was limited, the excipients tended to enhance pharmacodynamic effects. The excipients did not activate platelets in the absence of agonist and did not alter activation of platelets in response to adenosine diphosphate, arachidonic acid, thrombin, or convulxin (a collagen mimetic). Lipid excipients used in an oral formulation of aspirin do not impair the pharmacodynamic effects of aspirin and do not alter platelet function.

Assessment of Cardiovascular Risk by the Combination of Clinical Risk Scores Plus Platelet Expression of FcγRIIa.

Platelet expression of FcγRIIa was quantified after myocardial infarction (MI) and we found that patients with high platelet FcγRIIa expression (>11,000/platelet) had a fourfold greater risk of subsequent MI, stroke, and death. This analysis of the original cohort of 197 patients was designed to determine whether platelet expression of FcγRIIa could be used in combination with clinical risk scores (GRACE [Global Registry of Acute Coronary Events] and DAPT [Dual Antiplatelet Therapy]) to refine cardiovascular risk assessment. Platelet expression of FcγRIIa quantified with the use of flow cytometry was broadly distributed in patients stratified into high and low risk groups based on clinical risk scores. In patients identified as high risk by the GRACE score, 62% had high platelet FcγRIIa expression. Similarly, in patients identified as high risk by DAPT, 55% had high platelet FcγRIIa expression. High platelet FcγRIIa expression discriminated high and low risk cohorts in patients with high cardiovascular risk defined by either the GRACE score (high platelet FcγRIIa 18.9% vs low platelet FcγRIIa 0%; odds ratio = 15.7, p = 0.06) or the DAPT score (high platelet FcγRIIa 15.4% vs low platelet FcγRIIa 3.7%; odds ratio = 5.6, p = 0.03) assessment. Platelet expression of FcγRIIa merits additional study to determine whether low platelet FcγRIIa expression can be used to guide early transition to aspirin monotherapy and high platelet FcγRIIa expression can be used to guide continuation of DAPT.

BARI 2D: A Reanalysis Focusing on Cardiovascular Events.

OBJECTIVE: To reanalyze the Bypass Angioplasty Revascularization Investigation 2 Diabetes trial using a new composite cardiovascular disease (CVD) outcome to determine how best to treat patients with type 2 diabetes mellitus and stable coronary artery disease. PATIENTS AND METHODS: From January 1, 2001, to November 30, 2008, 2368 patients with type 2 diabetes mellitus and angiographically proven coronary artery disease were randomly assigned to insulin-sensitizing (IS) or insulin-providing (IP) therapy and simultaneously to coronary revascularization (REV) or no or delayed REV (intensive medical therapy [MED]), with all patients receiving intensive medical treatment. The outcome of this analysis was a composite of 8 CVD events. RESULTS: Four-year Kaplan-Meier rates for the composite CVD outcome were 35.8% (95% CI, 33.1%-38.5%) with IS therapy and 41.6% (95% CI, 38.7%-44.5%) with IP therapy (P=.004). Much of this difference was associated with lower in-trial levels of fibrinogen, C-reactive protein, and hemoglobin A1c with IS therapy. Four-year composite CVD rates were 32.7% (95% CI, 30.0%-35.4%) with REV and 44.7% (95% CI, 41.8%-47.6%) with MED (P<.001). A beneficial effect of IS vs IP therapy was present with REV (27.7%; 95% CI, 24.0%-31.4% vs 37.5%; 95% CI, 33.6%-41.4%; P<.001), but not with MED (43.6%; 95% CI, 39.5%-47.7% vs 45.7%; 95% CI, 41.6%-49.8%; P=.37) (homogeneity, P=.05). This interaction between IS therapy and REV was limited to participants preselected for coronary artery bypass grafting (CABG). The lowest composite CVD rates occurred in patients preselected for CABG and assigned to IS therapy and REV (17.3%; 95% CI, 11.8%-22.8%). CONCLUSION: In the Bypass Angioplasty Revascularization Investigation 2 Diabetes trial, the IS treatment strategy and the REV treatment strategy each reduces cardiovascular events. The combination of IS drugs and CABG results in the lowest risk of subsequent CVD events. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00006305.

Surveillance and Management of Troponin Elevation after Vascular Surgery.

BACKGROUND: Postopertive troponin elevation may occur without typical or atypical cardiac symptoms and is associated with an increased 30-day morbidity and mortality. The objective of the study was to implement a quality improvement initiative of postoperative troponin surveillance algorithm aimed at intensifying medical management after vascular surgery. METHODS: We conducted a single-center study of postoperative troponin surveillance after vascular surgery (n = 201) at a tertiary care, academic medical center from January to December 2016. Troponin surveillance was performed on postoperative days 1-3 after carotid endarterectomy, endovascular aortic repair, infrainguinal bypass, open abdominal aortic aneurysm repair, peripheral vascular intervention, and suprainguinal bypass, regardless of cardiac symptoms. Patients with troponin I elevation (>0.034 ng/mL) were managed with a treatment algorithm which included single or dual antiplatelet (AP) agent, high-intensity statin therapy, smoking cessation consultation, and outpatient cardiology consultation and stress testing. Patients with troponin elevation ≥1.0 ng/mL received inpatient cardiology consultation. We assessed adherence to the protocol for intensification of best medical therapy defined as high-dose statin therapy, increase in AP therapy, and smoking cessation consultation according to the established algorithm. RESULTS: Troponin elevation was recorded in 17% (34/201) of patients and was associated with cardiac symptoms in 8 patients (24%), while 26 (76%) patients had an asymptomatic abnormal troponin on postoperative surveillance. One patient was excluded due to death immediately after SUPRA, resulting in 200 patients. Troponin elevation ≥1.0 ng/mL occurred in 11 asymptomatic patients (5.5%). Any intensification of medical therapy was instituted in 76% of patients with elevated troponin and included high-intensity statin therapy (58%), increase in AP therapy (18%), and smoking cessation consultation (66%). Once an elevated troponin level was recognized, 52% of our patients received cardiology consultation with an increased likelihood (100%) in patients with troponin ≥1 ng/mL (P < 0.001). Adherence to outpatient stress testing was 66%. Intensification of medical therapy was not significantly different between patients with abnormal troponin values, >0.034-1.0 (n = 23) versus ≥1.0 ng/mL (n = 10); statin therapy (P = 1.0), AP (P = 0.34), and smoking cessation (P = 1.0). One-year mortality was higher in patients with postoperative troponin elevation than those with normal postoperative troponin levels (12% vs. 2.4%; P = 0.03). CONCLUSIONS: Routine postoperative troponin surveillance results in intensification of statin therapy in patients with asymptomatic troponin elevation. Further study is needed to determine if this approach reduces long-term cardiovascular morbidity and mortality.

Antiplatelet therapy for patients undergoing coronary artery bypass surgery.

Considerable variation in the use and duration of antiplatelet medications during the perioperative and postoperative care of patients undergoing coronary artery bypass grafting (CABG) reflects the limited number of studies focused directly on these patients as well as the variation in the results reported. In this review we highlight the incidence and mechanisms of graft closure as well as the evidence in support of antiplatelet therapy that is balanced by the impact of antiplatelet therapy on the risk of bleeding to provide recommendations for the use of this therapy in patients undergoing CABG. Low-dose acetylsalicylic acid (ASA; ≤ 160 mg daily) reduces the incidence of perioperative myocardial infarction, acute renal injury, and mortality without increasing the risk of bleeding and so is recommended both before and after CABG. The use of dual antiplatelet therapy with ASA plus a P2Y12 antagonist adds a greater risk of bleeding. While additional studies are required, we can make the following recommendations: because of increased bleeding and mortality when patients are treated with clopidogrel preoperatively, CABG should be delayed for five days. Because of increased bleeding when patients are treated with ticagrelor preoperatively, CABG should be delayed for three days. Because of increased bleeding when patients are treated with prasugrel preopera-tively, CABG should be delayed for seven days. For patients who had a coronary stent placed preoperatively or had an acute coronary syndrome preoperatively, resumption of therapy with their P2Y12 antagonist postoperatively for 12 months reduces the subsequent incidence of cardiovascular events.

Underutilization of antiplatelet and statin therapy after postoperative myocardial infarction following vascular surgery.

OBJECTIVE: The objective of this study was to investigate adherence to practice guidelines for antiplatelet and statin use after postoperative myocardial infarction (POMI) and its effect on late mortality following vascular surgery in a multicenter registry. METHODS: Antiplatelet and statin use was examined in 1749 vascular surgery procedures with POMI within the Vascular Quality Initiative (VQI) from 2005 to 2015. Our primary aim was to assess cardiac medication (CM) use at discharge, defined as (1) single antiplatelet therapy (SAPT; aspirin or P2Y12 inhibitor) or dual antiplatelet therapy (DAPT; aspirin and P2Y12 inhibitor) and (2) statin therapy. Long-term mortality in patients with POMI was analyzed on the basis of discharge CM. A proportional hazards model was developed to control for factors associated with mortality. Regional differences in CM use at discharge after POMI were compared. RESULTS: Overall discharge CM use after POMI included aspirin (81%), P2Y12 inhibitor (38%), statin therapy (76%), and combined antiplatelet and statin (74%). At discharge, 26% of patients were not receiving combined antiplatelet and statin therapy. SAPT (50%) was more common than DAPT (35%; P < .001). Patients with POMI undergoing carotid endarterectomy were more likely to be discharged on CM (80%) compared with patients undergoing infrainguinal bypass (78%), suprainguinal bypass (72%), endovascular aneurysm repair (71%), and open abdominal aortic aneurysm repair (59%; P < .001). Patients receiving SAPT or DAPT plus statin therapy had improved survival (79%) compared with those receiving noncombination or no therapy (69%) with mean follow-up of 5.5 years and 4.9 years, respectively (log-rank, P = .001). After adjustment for covariates including preoperative medications, treatment with SAPT or DAPT plus statin at discharge was associated with lower late mortality compared with noncombination or no therapy (hazard ratio, 0.72; 95% confidence interval, 0.56-0.93; P = .01). Regional variation in CM at discharge following POMI was also observed with a range of 33% to 100% (P = .05). CONCLUSIONS: Within the VQI, regional and procedure-specific variation exists in CM regimen after POMI following vascular surgery. Absence of combined antiplatelet and statin therapy at discharge after POMI was associated with higher late mortality and represents an area for quality improvement in the care of these patients.

International Expert Consensus on Switching Platelet P2Y12 Receptor-Inhibiting Therapies.

Dual antiplatelet therapy with aspirin and a P2Y12 inhibitor is the treatment of choice for the prevention of atherothrombotic events in patients with acute coronary syndromes and for those undergoing percutaneous coronary interventions. The availability of different oral P2Y12 inhibitors (clopidogrel, prasugrel, ticagrelor) has enabled physicians to contemplate switching among therapies because of specific clinical scenarios. The recent introduction of an intravenous P2Y12 inhibitor (cangrelor) further adds to the multitude of modalities and settings in which switching therapies may occur. In clinical practice, it is not uncommon to switch P2Y12 inhibitor, and switching may be attributed to a variety of factors. However, concerns about the safety of switching between these agents have emerged. Practice guidelines have not fully elaborated on how to switch therapies, leaving clinicians with limited guidance on when and how to switch therapies when needed. This prompted the development of this expert consensus document by key leaders from North America and Europe with expertise in basic, translational, and clinical sciences in the field of antiplatelet therapy. This expert consensus provides an overview of the pharmacology of P2Y12 inhibitors, different modalities and definitions of switching, and available literature and recommendations for switching between P2Y12 inhibitors.

Platelet phenotype changes associated with breast cancer and its treatment.

Platelets and their granular contents influence both angiogenesis and breast cancer progression. This study was performed to assess the effect of breast cancer and its treatment on platelet biology and the response to inhibition of the platelet P2Y12 receptor. Receptor-specific platelet activation and inhibition was studied for three platelet-associated proteins important in cancer angiogenesis and progression, vascular endothelial growth factor (VEGF), thrombospondin1 (TSP1), and transforming growth factor beta 1 (TGF-ß1). Twenty-four women with active breast cancer and 10 healthy controls not receiving antiplatelet therapy participated in the study. Ex vivo activation of platelets in whole blood was accomplished using PAR1AP, PAR4AP, convulxin, and ADP. Platelet inhibition was accomplished using the P2Y12 receptor antagonist cangrelor (the in vitro equivalent of clopidogrel). VEGF, TSP1, and TGF-ß1 were measured using standard ELISA. Platelet activation by ADP, PAR1, PAR4, and collagen receptors increased VEGF, TSP1, and TGF-ß1 secretion in patients with breast cancer. Agonist-induced release of VEGF was greater in cancer patients as compared to healthy controls (p = 0.02 for ADP, p < 0.001 for PAR1AP, PAR4AP, and convulxin) despite a decrease in the efficiency of VEGF secretion in patients with breast cancer. These differences were not observed for TSP1 and TGF-ß1 secretion. P2Y12 receptor inhibition decreased VEGF, TSP1, and TGF-ß1 secretion. In patients with cancer, cangrelor inhibited TSP1 release to a greater extent than VEGF and TGF-ß1 release. In patients with breast cancer, the magnitude of platelet inhibition achieved by cangrelor was greater than that achieved with healthy controls for all agonists and platelet proteins studied. While platelets are known to influence progression of breast cancer, our results show that breast cancer and its treatment influence the platelet phenotype by increasing the secretion of pro-angiogenic proteins following platelet activation, modulating the efficiency of platelet protein release as well as increasing the response to antiplatelet therapy.

Factors influencing platelet reactivity in patients undergoing coronary artery bypass surgery.

OBJECTIVE: Because coronary artery bypass graft (CABG) surgery is associated with a high turnover of platelets, assessment of platelet function should enable assessment of the effect of young (RNA-containing) platelets on platelet reactivity. This study was designed to assess platelet reactivity 1 day after CABG in patients treated previously with clopidogrel or ticagrelor. METHODS: Patients (n=18) with acute coronary syndrome who required urgent CABG and had been treated for up to 2 days before surgery with aspirin plus clopidogrel (n=13) or aspirin plus ticagrelor (n=5) were enrolled. Care was not altered by participation, which entailed review of medical records and taking one sample of blood 1 day after surgery. The percentage of RNA-containing platelets was quantified using thiazole orange, and platelet function was assessed by flow cytometry. RESULTS: Young platelets constituted, on average, 24% of platelets (range 4-54%) and were more likely to be activated in the absence or presence of an agonist (P<0.001). Differences between RNA-containing (young) and non-RNA-containing platelets were evident in patients treated previously with clopidogrel (P<0.001), whereas a nonsignificant trend was apparent in patients treated previously with ticagrelor. A high but variable prevalence of young platelets was seen 1 day after CABG. CONCLUSION: Young platelets were more reactive and, consistent with the irreversible binding of clopidogrel to P2Y12, this effect was more pronounced after treatment with clopidogrel. The reversible binding of ticagrelor to the platelet P2Y12 receptor may be advantageous in patients with a high platelet turnover.

Transition strategies from cangrelor to oral platelet P2Y12 receptor antagonists.

Cangrelor is the first parenteral antagonist of the platelet P2Y12 receptor. This direct-acting antagonist of the platelet P2Y12 receptor should be considered an adjunct to a percutaneous coronary intervention in patients who have not been adequately pretreated with platelet P2Y12 receptor antagonists at the time of the procedure. The use of cangrelor requires transition to an oral platelet P2Y12 receptor antagonist. Transition strategies have been developed on the basis of pharmacologic characteristics of platelet P2Y12 receptor antagonists, results of pharmacodynamic studies, and results from clinical trials. Cangrelor blocks the binding to the platelet P2Y12 receptor of the active metabolite of the thienopyridines, clopidogrel and prasugrel. The active metabolite of thienopyridines is present in blood for a short interval after administration. For this reason, clopidogrel should be administered after cangrelor is stopped. Prasugrel can be administered at the end of the cangrelor infusion or up to 30 min before cangrelor is stopped. Ticagrelor is also a reversible direct-acting antagonist of the platelet P2Y12 receptor. Because there is no interaction between ticagrelor and cangrelor, ticagrelor can be administered before or during the infusion of cangrelor.

Pharmacodynamic Effects When Clopidogrel is Given Before Cangrelor Discontinuation.

OBJECTIVE: To determine whether initiation of clopidogrel before discontinuation of cangrelor would impact on the recovery of platelet reactivity. BACKGROUND: The active metabolite of clopidogrel cannot bind to P2Y12 when cangrelor occupies the receptor. Pharmacodynamic studies have shown that this interaction is avoided when clopidogrel is given at the end of the cangrelor infusion. We found that antiplatelet effects of another thienopyridine, prasugrel, were apparent when prasugrel was administered 0.5 hour before cangrelor was stopped. METHODS: Platelet function studies (light transmission aggregometry, VerifyNow, and flow cytometry) were performed on blood from patients with stable coronary artery disease who were taking aspirin when a loading dose of clopidogrel (600 mg) was given during a cangrelor infusion (0.5 and 1 hour before cangrelor was stopped). Results were compared with those obtained when clopidogrel was given immediately after cangrelor was stopped. RESULTS: Administration of clopidogrel 0.5 and 1 hour before discontinuation of the cangrelor infusion did not prevent recovery of platelet reactivity more effectively than administration at the end of the infusion. CONCLUSION: Our results support the previously established strategy of administering clopidogrel immediately after discontinuation of cangrelor. Earlier administration increases the recovery of platelet function.

Pharmacodynamic effects during the transition between cangrelor and prasugrel.

OBJECTIVE: The aim of this study was to determine the impact of cangrelor and prasugrel on the pharmacodynamic effects of each agent. BACKGROUND: The development of an intravenous P2Y12 antagonist necessitates transition between intravenous and oral therapy. METHODS: Patients (n=15) with stable coronary artery disease who were taking 81 mg aspirin daily were recruited. On study day 1, they received a bolus plus 2-h infusion of cangrelor plus a 60 mg dose of prasugrel at 1 h (n=3), 1.5 h (n=6), 2 h (n=3), or 2.5 h (n=3). Pharmacodynamic effects (light transmission platelet aggregation in response to 20 µmol/l ADP, VerifyNow, and flow cytometry) were assessed during and after the cangrelor infusion. Patients took 10 mg of prasugrel daily for either 5 days (n=6) or 6 days (n=6). On study day 8, pharmacodynamic effects were assessed before and during a bolus plus 2-h infusion of cangrelor. RESULTS: During cangrelor infusion (days 1 and 8), extensive inhibition of platelet function, reflected by limited residual platelet reactivity, was apparent. On day 1, transient (limited to the first hour after cangrelor was stopped) but substantial (>50%) recovery of platelet reactivity was observed. This recovery was attenuated when prasugrel was given at 1.5 h (30 min before cangrelor was stopped). CONCLUSION: Prasugrel did not alter the antiplatelet effects of cangrelor, but transient recovery of platelet reactivity was apparent during the transition from cangrelor to prasugrel. Recovery of platelet reactivity was limited when prasugrel was administered 30 min before the end of the cangrelor infusion.

Pharmacodynamic effects during the transition between cangrelor and ticagrelor.

OBJECTIVES: This study sought to determine pharmacodynamic effects during transition from intravenous cangrelor to oral ticagrelor and from oral ticagrelor to intravenous cangrelor. BACKGROUND: Cangrelor is an intravenous antagonist of P2Y12 and its use will require transition to and from oral agents. METHODS: Patients (n = 12) with stable coronary artery disease who were taking aspirin 81 mg daily were recruited. On study day 1, they received a bolus plus 2-h infusion of cangrelor plus a 180-mg dose of ticagrelor at either 0.5 h (n = 6) or 1.25 h (n = 6). Pharmacodynamic effects (light transmission platelet aggregation in response to 20 and 5 µmol/l adenosine diphosphate, VerifyNow, P2Y12 assay (Accumetrics, San Diego, California), vasodilator-stimulated phosphoprotein index, and flow cytometry) were assessed during and after the cangrelor infusion. Patients took 90 mg of ticagrelor twice daily for either 6 (n = 6) or 7 (n = 6) doses. On study day 5, pharmacodynamic effects were assessed before and during a bolus plus 2-h infusion of cangrelor. RESULTS: During cangrelor infusion, extensive inhibition of platelet function reflected by limited residual platelet reactivity was apparent. After cangrelor was stopped, the antiplatelet effects of ticagrelor were preserved despite a modest increase in platelet reactivity. CONCLUSIONS: Ticagrelor given before or during infusion of cangrelor did not attenuate the pharmacodynamic effects of cangrelor. The pharmacodynamic effects of ticagrelor were preserved when ticagrelor was given during infusion of cangrelor. Consistent with the reversible binding of ticagrelor, this oral P2Y12 antagonist can be administered before, during, or after treatment with cangrelor.

Functional, structural and phylogenetic analysis of domains underlying the Al sensitivity of the aluminum-activated malate/anion transporter, TaALMT1.

Triticum aestivum aluminum-activated malate transporter (TaALMT1) is the founding member of a unique gene family of anion transporters (ALMTs) that mediate the efflux of organic acids. A small sub-group of root-localized ALMTs, including TaALMT1, is physiologically associated with in planta aluminum (Al) resistance. TaALMT1 exhibits significant enhancement of transport activity in response to extracellular Al. In this study, we integrated structure-function analyses of structurally altered TaALMT1 proteins expressed in Xenopus oocytes with phylogenic analyses of the ALMT family. Our aim is to re-examine the role of protein domains in terms of their potential involvement in the Al-dependent enhancement (i.e. Al-responsiveness) of TaALMT1 transport activity, as well as the roles of all its 43 negatively charged amino acid residues. Our results indicate that the N-domain, which is predicted to form the conductive pathway, mediates ion transport even in the absence of the C-domain. However, segments in both domains are involved in Al(3+) sensing. We identified two regions, one at the N-terminus and a hydrophobic region at the C-terminus, that jointly contribute to the Al-response phenotype. Interestingly, the characteristic motif at the N-terminus appears to be specific for Al-responsive ALMTs. Our study highlights the need to include a comprehensive phylogenetic analysis when drawing inferences from structure-function analyses, as a significant proportion of the functional changes observed for TaALMT1 are most likely the result of alterations in the overall structural integrity of ALMT family proteins rather than modifications of specific sites involved in Al(3+) sensing.

Effect of exercise training and weight loss on platelet reactivity in overweight patients with coronary artery disease.

PURPOSE: Obesity is associated with increased platelet reactivity. Greater platelet reactivity presages adverse events in patients with coronary artery disease (CAD). We investigated whether exercise training and weight loss reduce platelet reactivity in overweight subjects with CAD. METHODS: Study subjects (N = 46) were enrolled in a prospective randomized study of exercise training and behavioral weight loss, which contrasted the amount of exercise performed (750 vs. >3000 kcal/week). Platelet reactivity was assessed with the use of flow cytometry as the percentage of platelets expressing P-selectin or capable of binding fibrinogen in response to 1 µM adenosine diphosphate in blood before and after a 4-month program of exercise and behavioral weight loss. Markers of inflammation (high-sensitivity C-reactive protein), procoagulant activity (tissue plasminogen activator, plasminogen activator inhibitor 1), insulin sensitivity, body composition, physical activity, and fitness were also recorded. RESULTS: Platelet reactivity as assessed by P-selectin expression was decreased after exercise training and weight loss in study participants (from 34 ± 17% to 29 ± 17%; P = .01). The decrease was more pronounced in women (by 13% vs. 2% in men; P < .01). The change in platelet reactivity was not independently associated with measures of body composition or fitness. After controlling for exercise group and gender, the change in platelet reactivity was associated with changes in high-sensitivity C-reactive protein (r = 0.46) and insulin sensitivity (r = 0.46). CONCLUSIONS: In overweight patients with CAD, exercise training and weight loss are associated with a decrease in platelet reactivity that may predict an improved prognosis.

Increased local cytokine production at culprit superficial femoral artery plaques.

Characterization of local inflammation at culprit superficial femoral artery (SFA) stenosis has not been studied. We hypothesized that arterial cytokine concentrations would be greater at sites of stenosis. Twenty patients with ≥50 % angiographic stenosis of the SFA had blood drawn just proximal to the lesion and from a contralateral site free of disease. A microplate immunoassay was used to determine the concentrations of 42 distinct cytokines and growth factors. Exact conditional logistic analysis was used to compare measures at the two sites with interaction terms describing clinical factors used to identify difference mediators. Interaction terms identified clinical factors that could predict cytokine levels. The concentrations of soluble CD40 ligand (sCD40L; mean 212 and 177 pg/ml, p = 0.01) and tumor necrosis factor beta (TNF-B; mean 16.6 and 15.9 pg/ml, p = 0.04) were increased immediately proximal to areas of stenosis. Factors associated with greater concentrations at sites of stenosis were bilateral ankle-brachial index ≤0.90 (p = 0.04), no statin use (p = 0.02), claudication (p = 0.03), low leukocyte count (p = 0.03), absence of limb ischemia (p = 0.04) and lack of aspirin or clopidogrel therapy (p ≤ 0.06). Greater concentrations of sCD40L and TNF-B at sites of stenosis suggest that these cytokines play a role in the pathogenesis of symptomatic SFA disease. Our results also suggest that statin, aspirin and clopidogrel therapy may attenuate localized inflammation in the SFA, though due to a small sample size and the use of multiple comparisons across groups, these findings can be viewed as hypothesis generating only. In conclusion, selected cytokines are heightened at culprit SFA lesions and inflammation may be modulated by statin and antiplatelet therapy.