Inhibition Of Platelet Aggregation Research Articles

Antiplatelet therapy to prevent ischemic events in giant cell arteritis: protocol for a systematic review and meta-analysis

BackgroundGiant cell arteritis (GCA) is the most common systemic vasculitis in adults. Presenting features include new-onset headaches, constitutional symptoms, jaw claudication, polymyalgia rheumatica, and visual symptoms. Arterial inflammation with subsequent stenosis and occlusion may cause tissue ischemia, leading to blindness, strokes, and myocardial infarction. Oral antiplatelet therapy has been hypothesized to reduce GCA-related ischemic events. However, previous studies have demonstrated conflicting results regarding the efficacy of antiplatelet agents in GCA. The objective of this systematic review is to assess the safety and efficacy of antiplatelet therapy for the prevention of these events in adults with giant cell arteritis.MethodsIn this systematic review, we will include randomized controlled trials (RTCs), quasi-randomized trials, non-randomized intervention studies, cohort studies, and case–control studies on patients with new-onset or relapsing GCA. The intervention of interest will be pre-existing use or initiation of an oral antiplatelet medication (aspirin, clopidogrel, prasugrel, or ticagrelor) at GCA onset or relapse. The comparator of interest will be the absence of antiplatelet therapy. Endpoints will be evaluated after 6 and 12 months of follow-up. The primary outcome will be GCA-related ischemic events, including permanent blindness, stroke, myocardial infarction, and ischemic event-related deaths. Adverse events such as major bleeding and death caused by a bleeding event will be assessed.DiscussionGCA-related ischemic events are catastrophic, sudden, often irreversible, and lead to significant morbidity. Antiplatelet agents are affordable, accessible, and could be effective for the prevention of these events. Nevertheless, the potential benefits of platelet aggregation inhibition must be weighed against their associated risk of bleeding. Assessing the efficacy and safety of antiplatelet therapy in GCA is therefore clinically important.Systematic review registrationOur systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO, registration number CRD42023441574.

Antiplatelet therapy to prevent ischemic events in giant cell arteritis: protocol for a systematic review and meta-analysis

BackgroundGiant cell arteritis (GCA) is the most common systemic vasculitis in adults. Presenting features include new-onset headaches, constitutional symptoms, jaw claudication, polymyalgia rheumatica, and visual symptoms. Arterial inflammation with subsequent stenosis and occlusion may cause tissue ischemia, leading to blindness, strokes, and myocardial infarction. Oral antiplatelet therapy has been hypothesized to reduce GCA-related ischemic events. However, previous studies have demonstrated conflicting results regarding the efficacy of antiplatelet agents in GCA. The objective of this systematic review is to assess the safety and efficacy of antiplatelet therapy for the prevention of these events in adults with giant cell arteritis.MethodsIn this systematic review, we will include randomized controlled trials (RTCs), quasi-randomized trials, non-randomized intervention studies, cohort studies, and case–control studies on patients with new-onset or relapsing GCA. The intervention of interest will be pre-existing use or initiation of an oral antiplatelet medication (aspirin, clopidogrel, prasugrel, or ticagrelor) at GCA onset or relapse. The comparator of interest will be the absence of antiplatelet therapy. Endpoints will be evaluated after 6 and 12 months of follow-up. The primary outcome will be GCA-related ischemic events, including permanent blindness, stroke, myocardial infarction, and ischemic event-related deaths. Adverse events such as major bleeding and death caused by a bleeding event will be assessed.DiscussionGCA-related ischemic events are catastrophic, sudden, often irreversible, and lead to significant morbidity. Antiplatelet agents are affordable, accessible, and could be effective for the prevention of these events. Nevertheless, the potential benefits of platelet aggregation inhibition must be weighed against their associated risk of bleeding. Assessing the efficacy and safety of antiplatelet therapy in GCA is therefore clinically important.Systematic review registrationOur systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO, registration number CRD42023441574.

Stilbene-pyridazinone hybrids: design, synthesis and in vitro antiplatelet activity screening

A series of stilbene analogues, in which a phenyl ring was replaced by the pyridazin-3(2H)-one nucleus, was designed and synthesized to be explored as platelet aggregation inhibitors. The proposed stilbene-pyridazinone hybrids were successfully obtained from simple starting materials and by Wittig’s reaction. Most of the target compounds displayed improved in vitro activity in comparison with the standard drug, resveratrol, highlighting as the most potent the analogues 10d and 10e, with inhibition percentages of 94.15 % at 100 µM and 100 % at 50 µM, respectively.The pharmacokinetic and toxicity (ADME/T) properties of the novel hybrids were also estimated with the SwissADME and ProTox-II web servers.

Antiplatelet Activity of Phenolic Compounds-Fortified Merlot Wine and Pure Phenolic Compounds

Red wines and their pomace are valuable sources of phenolic compounds (PCs), which have been proposed as potential contributors to their cardioprotective effect through the inhibition of platelet aggregation. The antiplatelet activity of an extract depends on its chemical composition, specifically the presence of certain phenolic compounds, as well as the interactions between them affecting biological activity. In order to assess the effect on platelet aggregation, we investigated the effect of the grape pomace PC enrichment of a Merlot wine, as well as the effect of the five major phenolic compounds present in wine extracts: caffeic acid, gallic acid, quercetin, epicatechin, and catechin. We analyzed how their combination influenced platelet aggregation. We found that the fortified wine sample with the highest PC content (W8) exhibited a potent antiplatelet effect in aggregation and platelet activation assays induced by the agonists TRAP-6, collagen, and ADP, with its activity being most potent against the latter agonist (78 ± 4%). Among the evaluated phenolic compounds, quercetin showed the highest antiplatelet potential against all three agonists studied, while gallic acid showed minimal antiplatelet effect. These findings suggest that the cardioprotective effect of wines is related to their chemical composition and the synergy among phenolic compounds. However, further research is required to fully understand the underlying mechanisms and clinical relevance of this activity.

Advances in the Anti-Atherosclerotic Mechanisms of Epigallocatechin Gallate.

Atherosclerosis (AS) is a common clinical sickness and the major pathological basis of ischemic cardiocerebrovascular diseases (CCVDs). The pathogenesis of AS involves a variety of risk factors, and there is a lack of effective preventive and curative drugs that can completely treat AS. In recent years, with the improvement of people's living standards and changes in dietary habits, the morbidity and mortality rates of AS are on the rise, and the age of onset tends to be younger. The formation of AS is closely related to a variety of factors, and the main factors include lipid metabolism disorders, endothelial damage, inflammation, unstable plaques, etc. Epigallocatechin gallate (EGCG), as one of the main components of catechins, has a variety of pharmacological effects, and its role in the prevention of AS and the protection of cardiovascular and cerebral blood vessels has been highly valued. Recent epidemiological investigations and various in vivo and ex vivo experiments have shown that EGCG is capable of resisting atherosclerosis and reducing the morbidity and mortality of AS. In this paper, we reviewed the anti-AS effects of EGCG and its mechanisms in recent years, including the regulation of lipid metabolism, regulation of intestinal flora disorders, improvement of vascular endothelial cell functions, inhibition of inflammatory factors expression, regulation of inflammatory signaling pathways, inhibition of matrix metalloproteinase (MMP) expression, and inhibition of platelet aggregation, which are helpful for the prevention of cardiocerebrovascular diseases.

Analysis of the effect of CYP2C19 gene properties on the anti-platelet aggregation of clopidogrel after carotid artery stenting under network pharmacology

Antiplatelet therapy is an important factor influencing the postterm patency rate of carotid artery stenting (CAS). Clopidogrel is a platelet aggregation inhibitor mediated by the adenosine diphosphate receptor and is affected by CYP2C19 gene polymorphisms in vivo. When the CYP2C19 gene has a nonfunctional mutation, the activity of the encoded enzyme will be weakened or lost, which directly affects the metabolism of clopidogrel and ultimately weakens its antiplatelet aggregation ability. Therefore, based on network pharmacology, analyzing the influence of CYP2C19 gene polymorphisms on the antiplatelet therapeutic effect of clopidogrel after CAS is highly important for the formulation of individualized clinical drug regimens. The effect of the CYP2C19 gene polymorphism on the antiplatelet aggregation of clopidogrel after CAS was analyzed based on network pharmacology. A total of 100 patients with ischemic cerebrovascular disease who were confirmed by the neurology department and required CAS treatment were studied. CYP2C19 genotyping was performed on all patients via a gene chip. All patients were classified into the wild-type (WT) group (*1/*1), heterozygous mutation (HTM) group (CYP2C19*1/*2, CYP2C19*1/*3), and homozygous mutation (HMM) group (CYP2C19*2/*2, CYP2C19*2/*3, and CYP2C19*3/*3). High-performance liquid chromatography (HPLC) with tandem mass spectrometry (MS/MS) was used to detect the blood concentration of clopidogrel and the plasma clopidogrel clearance (CL) rate in different groups of patients before and after clopidogrel treatment. The platelet aggregation rate of patients with different genotypes was measured by turbidimetry. The incidences of clopidogrel resistance (CR) and stent thrombosis in different groups after three months of treatment were analyzed. The results showed that among the different CYP2C19 genotypes, patients from the HTM group accounted for the most patients, while patients from the HTM group accounted for the least patients. Similarly, the clopidogrel CL of patients in the HMM group was lower than that of patients in the WT group and HTM group (P < 0.01). The platelet inhibition rate of patients in the HMM group was evidently inferior to that of patients in the WT group and HTM group (P < 0.01). The incidence of CR and stent thrombosis in the WT group was notably lower than that in the HTM and HMM groups (P < 0.01). These results indicate that the CYP2C19 gene can affect CR occurrence and stent thrombosis after CAS by influencing clopidogrel metabolism and platelet count.

Clopidogrel resistance and its relevance: Current concepts

ABSTRACT Clopidogrel is the most widely used P2Y12 receptor inhibitor (P2Y12i) as a part of dual antiplatelet therapy along with aspirin. Clopidogrel is a pro-drug and is metabolized to its active metabolite by the hepatic enzyme cytochrome P4502C19 (CYP2C19). This active metabolite is responsible for the antiplatelet action of clopidogrel. Recent studies have demonstrated that single nucleotide polymorphisms in the CYP2C19 gene, including CYP2C19*2,*3,*4, and *5 alleles, result in reduced production of the active metabolite of clopidogrel, and hence reduced inhibition of platelet aggregation. This in turn enhances the incidence of stent thrombosis and recurrent cardiovascular (CV) events. We report a case of coronary stent thrombosis due to clopidogrel resistance proven by CYP2C19 genotyping. We then review the literature on clopidogrel resistance and its impact on CV outcomes. Subsequently, we discuss the methods of diagnosis of resistance, evidence from clinical trials for tailoring clopidogrel therapy, the role of potent P2Y12 inhibitors, the current guidelines, and future directions.

Small-Molecule Disruptors of the Interaction between Calcium- and Integrin-Binding Protein 1 and Integrin αIIbβ3 as Novel Antiplatelet Agents.

Thrombosis, a key factor in most cardiovascular diseases, is a major contributor to human mortality. Existing antithrombotic agents carry a risk of bleeding. Consequently, there is a keen interest in discovering innovative antithrombotic agents that can prevent thrombosis without negatively impacting hemostasis. Platelets play crucial roles in both hemostasis and thrombosis. We have previously characterized calcium- and integrin-binding protein 1 (CIB1) as a key regulatory molecule that regulates platelet function. CIB1 interacts with several platelet proteins including integrin αIIbβ3, the major glycoprotein receptor for fibrinogen on platelets. Given that CIB1 regulates platelet function through its interaction with αIIbβ3, we developed a fluorescence polarization (FP) assay to screen for potential inhibitors. The assay was miniaturized to 1536-well and screened in quantitative high-throughput screening (qHTS) format against a diverse compound library of 14,782 compounds. After validation and selectivity testing using the FP assay, we identified 19 candidate inhibitors and validated them using an in-gel binding assay that monitors the interaction of CIB1 with αIIb cytoplasmic tail peptide, followed by testing of top hits by intrinsic tryptophan fluorescence (ITF) and microscale thermophoresis (MST) to ascertain their interaction with CIB1. Two of the validated hits shared similar chemical structures, suggesting a common mechanism of action. Docking studies further revealed promising interactions within the hydrophobic binding pocket of the target protein, particularly forming key hydrogen bonds with Ser180. The compounds exhibited a potent antiplatelet activity based on their inhibition of thrombin-induced human platelet aggregation, thus indicating that disruptors of the CIB1- αIIbβ3 interaction could carry a translational potential as antithrombotic agents.

Safety, Tolerability, and Pharmacodynamics of AZD3366 (Optimized Human CD39L3 Apyrase) Alone and in Combination With Ticagrelor and Acetylsalicylic Acid: A Phase 1, Randomized, Placebo-Controlled Study.

ADP and ATP are importantly involved in vascular and thrombotic homeostasis, via multiple receptor pathways. Blockade of ADP P2Y12 receptors inhibits platelet aggregation and represents an effective cardiovascular disease prevention strategy. AZD3366 (APT102), a long-acting recombinant form of an optimized CD39L3 human apyrase, has effectively reduced ATP, ADP, and platelet aggregation and provided tissue protection in preclinical models, features that could be very beneficial in treating patients with cardiovascular disease. We conducted this phase 1, first-in-human study of single ascending doses of intravenous AZD3366 or placebo, including doses added to dual antiplatelet therapy with ticagrelor and acetylsalicylic acid. The primary objective was safety and tolerability; secondary and exploratory objectives included pharmacokinetics, pharmacodynamics (measured as inhibition of platelet aggregation), adenosine diphosphatase (ADPase) activity, and ATP/ADP metabolism. In total, 104 participants were randomized. AZD3366 was generally well tolerated, with no major safety concerns observed. ADPase activity increased in a dose-dependent manner with a strong correlation to AZD3366 exposure. Inhibition of ADP-stimulated platelet aggregation was immediate, substantial, and durable. In addition, there was a prompt decrease in systemic ATP concentration and an increase in adenosine monophosphate concentrations, whereas ADP concentration appeared generally unaltered. At higher doses, there was a prolongation of capillary bleeding time without detectable changes in the exvivo thromboelastometric parameters. AZD3366 was well tolerated in healthy participants and demonstrated substantial and durable inhibition of platelet aggregation after single dosing. Higher doses prolonged capillary bleeding time without detectable changes in exvivo thromboelastometric parameters. URL: https://www.clinicaltrials.gov; Unique Identifier: NCT04588727.

#1593 ARGDRR, a novel disintegrin, attenuates AKI to CKD-related renal fibrosis

Abstract Background and Aims Acute kidney injury (AKI) can lead to progress renal fibrosis, resulting in chronic kidney disease (CKD) and end stage renal disease (ESRD). Nevertheless, the underlying pathological mechanisms remain unclear. Platelet activation has been demonstrated as one of the important factors involved in the pathophysiology of AKI, and studies show the therapeutic potential for using platelet inhibitors or antagonists in ischemia-reperfusion (IR)-induced AKI models. However, drug-induced side effects, including thrombotic microangiopathies (TMA)-related kidney damage, thrombocytopenia and bleeding, hinder clinical application in AKI or CKD treatment. Our newly developed dual effect disintegrin, ARGDRR, is derived from snake venom exert a high affinity to αIIbβ3 and αvβ3 binding affinity without causing bleeding and other thrombosis-related side effects. Method We performed a unilateral ischemia-reperfusion injury (UIRI) model to investigate integrin αIIb(Itga2b) and β3(Itgb3) mRNA levels in the injured kidney for 15 days. For exploring the therapeutic efficiency of ARGDRR in AKI, we administered ARGDRR post-ischemic injury and measured platelet activation after 24 hours using quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC) for Itgb3, Lcn2, and CD42b. For exploring the therapeutic efficiency of ARGDRR in CKD progression, we administrated ARGDRR daily for 15 days after IRI with nephrectomy, and examined the difference of renal dysfunction, renal fibrosis, and cell death compared to sham group. Results We found that platelet activation with progressively increased mRNA level of platelet glycoprotein IIb-GPIIIa (Itga2b and Itgb3) in the UIRI kidney over time. After 24 hr of ischemic AKI, ARGDRR administration reduced Lcn2 and Itgb3 mRNA level and CD42b positive area in the kidney, indicating its efficacy in protecting the kidneys by inhibiting platelet activation and aggregation. In AKI to CKD transition, serum creatine and blood urea nitrogen (BUN) were significantly lower both in efficacious and high dose of ARGDRR administration group. ARGDRR significantly reduced CD42b expression and increased LTL positive area. Also, ARGDRR administration alleviated renal fibrosis, cell apoptosis and senescence-related molecules p21 and Ctgf expression in the AKI to CKD transition. Conclusion Our results have successfully proved our hypothesis that disintegrin-ARGDRR has the potential for renal protection in the transition of AKI to CKD through inhibition of platelet activation and aggregation during acute injury.

The Inhibitory Effect of Platelet Aggregation Ability Assessed by the Platelet Aggregatory Threshold Index in a Patient with Recurrent Stent Thrombosis.

An 86-year-old man successfully underwent percutaneous coronary intervention (PCI), in which a drug-coated stent (DCS) was placed in the left anterior descending coronary artery. However, stent thrombosis occurred twice after eight and two months. After the second admission, the patient was tested for platelet aggregation activity using the platelet aggregation threshold index (PATI), and insufficient inhibition of platelet aggregation was observed. The patient's PATI improved to a satisfactory level using oral anticoagulants. At the six-month follow-up, clinical events were observed. Measuring the platelet aggregation ability can help clinicians understand the pathology of patients and determine treatment choices.

Comparative genomics of two Asian medicinal leeches Hirudo nipponia and Hirudo tianjinensis: With emphasis on antithrombotic genes and their corresponding proteins

Leeches secrete various biologically active substances which have important medical and pharmaceutical values in antithrombotic treatments. Here, we provide a high quality genome of two Asian medicinal leeches Hirudo nipponia and Hirudo tianjinensis, based on which, we identified 22 antithrombotic gene families, including fourteen coagulation inhibitors, four platelet aggregation inhibitors, three fibrinolysis enhancers, and one tissue penetration enhancer. The total numbers of antithrombotic genes were similar between H. nipponia (N = 86) and H. tianjinensis (N = 83). Molecular evolution analysis showed that no significant differences were detected between the two species in any of the three selection indices (dN, dS, and dN/dS), nor in the number of sites under positive/purifying selection. RNA-Seq based gene expression analysis showed that the overall expression patterns of the antithrombotic gene families were not significantly deviated between the two species. Our results indicated that there were rather close similarities between the two leeches on genomic characteristics, especially for the molecular evolution and expression of antithrombotic genes. Our study provides the most comprehensive collection of antithrombotic biomacromolecules from the two Asian medicinal leeches to date. These results will greatly facilitate the research and application of leech derivatives for medical and pharmaceutical purposes of thrombosis.

Comprehensive Analysis of Drug Utilization Patterns, Gender Disparities, Lifestyle Influences, and Genetic Factors: Insights from Elderly Cohort Using g-Nomic® Software.

Polypharmacy is a global healthcare concern, especially among the elderly, leading to drug interactions and adverse reactions, which are significant causes of death in developed nations. However, the integration of pharmacogenetics can help mitigate these risks. In this study, the data from 483 patients, primarily elderly and polymedicated, were analyzed using Eugenomic®'s personalized prescription software, g-Nomic®. The most prescribed drug classes included antihypertensives, platelet aggregation inhibitors, cholesterol-lowering drugs, and gastroprotective medications. Drug-lifestyle interactions primarily involved inhibitions but also included inductions. Interactions were analyzed considering gender. Significant genetic variants identified in the study encompassed ABCB1, SLCO1B1, CYP2C19, CYP2C9, CYP2D6, CYP3A4, ABCG2, NAT2, SLC22A1, and G6PD. To prevent adverse reactions and enhance medication effectiveness, it is strongly recommended to consider pharmacogenetics testing. This approach shows great promise in optimizing medication regimens and ultimately improving patient outcomes.

Selective binding of cationic fibrinogen-mimicking chitosan nanoparticles to activated platelets and efficient drug release for antithrombotic therapy

Thrombosis is the main cause of catastrophic events including ischemic stroke, myocardial infarction and pulmonary embolism. Acetylsalicylic acid (ASA) therapy offers a desirable approach to antithrombosis through a reduction of platelet reactivity. However, major bleeding complications, severe off-target side effects, and resistance or nonresponse to ASA greatly attenuate its clinical outcomes. Herein, we report a cationic fibrinogen-mimicking nanoparticle, denoted as ASA-RGD-CS@TPP, to achieve activated-platelet-targeted delivery and efficient release of ASA for safer and more effective antithrombotic therapy. This biomimetic antithrombotic system was prepared by one-pot ionic gelation between cationic arginine-glycine-aspartic acid (RGD)-grafted chitosan (RGD-CS) and anionic tripolyphosphate (TPP). The platform exhibited selective binding to activated platelets, leading to efficient release of ASA and subsequent attenuation of platelet functions, including the remarkable inhibition of platelet aggregation through a potent blockage of cyclooxygenase-1 (COX-1). After intravenous administration, ASA-RGD-CS@TPP displayed significantly prolonged circulation time and successful prevention of thrombosis in a mouse model. ASA-RGD-CS@TPP was demonstrated to significantly enhance antithrombotic therapy while showing minimal coagulation and hemorrhagic risks and excellent biocompatibility in vivo as compared to free ASA. This platform provides a simple, safe, effective and targeted strategy for the development of antithrombotic nanomedicines.

Apolipoprotein A-IV polymorphisms Q360H and T347S attenuate its endogenous inhibition of thrombosis

Platelets are small anucleate cells that play a key role in thrombosis and hemostasis. Our group previously identified apolipoprotein A-IV (apoA-IV) as an endogenous inhibitor of thrombosis by competitive blockade of the αIIbβ3 integrin on platelets. ApoA-IV inhibition of platelets was dependent on the N-terminal D5/D13 residues, and enhanced with absence of the C-terminus, suggesting it sterically hinders its N-terminal platelet binding site. The C-terminus is also the site of common apoA-IV polymorphisms apoA-IV-1a (T347S) and apoA-IV-2 (Q360H). Interestingly, both are linked with an increased risk of cardiovascular disease, however, the underlying mechanism remains unclear. Here, we generated recombinant apoA-IV and found that the Q360H or T347S polymorphisms dampened its inhibition of platelet aggregation in human platelet-rich plasma and gel-filtered platelets, reduced its inhibition of platelet spreading, and its inhibition of P-selectin on activated platelets. Using an ex vivo thrombosis assay, we found that Q360H and T347S attenuated its inhibition of thrombosis at both high (1800s−1) and low (300s−1) shear rates. We then demonstrate a conserved monomer-dimer distribution among apoA-IV WT, Q360H, and T347S and use protein structure modelling software to show Q360H and T347S enhance C-terminal steric hindrance over the N-terminal platelet-binding site. These data provide critical insight into increased cardiovascular risk for individuals with Q360H or T347S polymorphisms.

Polypharmacy in Older Patients: A Three-Year Longitudinal Analysis in Primary Care Settings of Aragón, Spain.

Challenges of polypharmacy and the impact of coronavirus disease 2019 (COVID-19) pandemic in older patients require further investigation. This retrospective study analyzed the progression of polypharmacy and anticholinergic burden in older patients in a primary care setting before, during, and after the COVID-19 pandemic. This 3-year cross-sectional study (2019, 2020, and 2021) comprised a dynamic cohort of individuals aged ≥75 years, who attended the Arrabal Primary Care Center in Zaragoza, Spain. Older patients with polypharmacy (≥5 medications) were identified according to their electronic health records. We collected demographic and clinical data, including medication prescriptions, diagnoses, and anticholinergic risks, and performed descriptive and statistical analyses. This study included a total of 1,928 patients with a mean age of 83.52±0.30 years. Over the 3-year study period, the mean number of medications prescribed increased, from 9.4 in 2019 to 10.4 in 2021. The prevalence of excessive polypharmacy (≥10 medications) increased from 39% in 2019 to 45% in 2021. The most commonly prescribed drugs were anilides, proton pump inhibitors, benzodiazepine derivatives, and platelet aggregation inhibitors. Women had a higher prevalence of illnesses and anticholinergic drug prescriptions than men. The results of this study highlighted an upward trend in polypharmacy and excessive polypharmacy among older patients in primary care settings. Future research should focus on optimizing medication management and deprescribing strategies and minimizing the adverse effects of polypharmacy in this population.

Factors associated with clopidogrel resistance and clinical outcomes in ischemic cerebrovascular disease: A retrospective study

ObjectiveClopidogrel resistance may lead to the recurrence of cerebrovascular diseases. We aimed to identify potential factors associated with clopidogrel resistance and evaluate the clinical outcomes of the patients. Materials and methodsIn this retrospective study, patients with ischemic cerebrovascular disease treated with clopidogrel were included and classified into 2 groups according to the adenosine diphosphate (ADP)-induced platelet aggregation. Patients with the ADP inhibition rate of <30 % were included in clopidogrel resistance group, otherwise were included in clopidogrel sensitive group. CYP2C19 genotype and other clinical data were analyzed to identify factors and clinical features in the multivariate analysis. The outcomes were vascular events in 6 months. ResultsIn total, 139 patients were enrolled with 81 (58.27 %) in clopidogrel sensitive group and 58 (41.73 %) in clopidogrel resistance group. Female and CYP2C19 *2*3 carrying were risk factors for clopidogrel resistance, and female was an independent risk factor (OR 2.481, 95 % CI 1.066-5.771, P=0.035). The clopidogrel resistance group showed a higher use rate of argatroban (P=0.030) and a lower arachidonic acid-induced inhibition of platelet aggregation (P=0.036). Clopidogrel resistance was related to the progressing stroke (HR 3.521, 95 % CI 1.352-9.170, P=0.010), but had no influence on the bleeding events (P>0.05). ConclusionsThe risk of clopidogrel resistance increased significantly in female patients. Patients with clopidogrel resistance may have an increased incidence of stroke progression in the acute phase.

(206) Strategies of Nitric Oxide Augmentation for PDE5 Inhibitors

Abstract Introduction Erectile function and endothelial functions are closely related entities. Nitric oxide NO regulates circulation and microcirculation involved in erection.NO concentration is reduced with aging, diabetes, environment pollution smoking, obesity, inflammation, high prolactin, low testosterone oxidative stress and atherosclerosis. Many of erectile dysfunction patients are PDE5 inhibitor resistant. Strategies to enhance NO expression, can be employed to convert treatment resistant patient into responder. Objective Employ every possible mechanism to augment nitric oxide expression. Greater base line nitric oxide better would be PDE5 inhibitor respose. Methods Internet search was made on various website including pub med, science direct, google scholars using key words like erection, erectile dysfunction, nitric oxide, l arginine, oxidative stress, antioxidant, NOS, endothelial dysfunction, atherosclerosis and etc. This was followed by literature study on given topic. Results Efficacy of PDE 5 inhibitor in ED treatment is 70%. NO concentration decline to 50% by age of 40 and is only 15% at age 60. Humming can increase nasal NO level up to 15 time. Conclusions NO regulates endothelial function, vasodilatation, platelet aggregation inhibition, free radical scavenging, testosterone synthesis and neuronal protection. Study of mechanism of NO production provides, strategies for its enhancement. L arginine, L citrulline, serve as substrate and vitamin C, tetrahydrobiopterin (BH4) act as co factors in production of NO. Endothelial nitric oxide synthase e NOS, neuronal nitric oxide synthase n NOS are major enzymes act involved in synthesis. Oxygen is required for NO synthesis process. Supplementation of substrate and cofactors help increase NO levels. Oxygen availability can be increased through exercise and raising hemoglobin level. Reactive oxygen species ROS convert NO into bioinactive peroxynitrite which itself is ROS. Oxidative stress can cause endothelial nitric oxide synthase uncoupling. Consequently eNOS start producing ROS. This causes oxidation of NOS and as well as of cofactor like BH4 and vitamin C. ROS also increase level of methylarginines. Antioxidant used to neutralize ROS include Co Q10, alpha lipoic acid, flavonoids, bioflavonoids poly phenols, pycnogenol, resveterol, fulvic acid and etc. Second mechanism NO production is from dietary nitrates. Nutritional nitrates are converted into nitrite by oral anaerobic bacteria’s. Nitrate rich foods like beet root or spinach are added to enhance nitrate based NO. Nitric oxide thus produced is used for vasodilatation of penile vessels as well sinuses of corpus cavernousm. Apart from that it inhibits uncoupling of NOS. This support L arginine based mechanism of NO production. Nitroglycerin or minoxidal act as NO donors. These agents can be used locally at glans penis to augment NO availability. Bee breathing is maneuver in which humming sound vibrates nasal sinus increasing NO production up to 15 folds. Inhaled NO act as bronchodilator which increase lung capacity leading to higher blood oxygen concentration. Various NO enhancement strategies thus applied, may convert non responder PDE5 inhibitor to responders. Disclosure No.

Cilostazol for peripheral arterial disease - a position paper from the Italian Society for Angiology and Vascular Medicine.

Cilostazol is a quinolinone-derivative selective phosphodiesterase inhibitor and is a platelet-aggregation inhibitor and arterial vasodilator for the symptomatic treatment of intermittent claudication (IC). Cilostazol has been shown to improve walking distance for patients with moderate to severe disabling intermittent claudication who do not respond to exercise therapy and who are not candidates for vascular surgical or endovascular procedures. Several studies evaluated the pharmacological effects of cilostazol for restenosis prevention and indicated a possible effect on re-endothelialization mediated by hepatocyte growth factor and endothelial precursor cells, as well as inhibiting smooth muscle cell proliferation and leukocyte adhesion to endothelium, thereby exerting an anti-inflammatory effect. These effects may suggest a potential effectiveness of cilostazol in preventing restenosis and promoting the long-term outcome of revascularization interventions. This review aimed to point out the role of cilostazol in treating patients with peripheral arterial disease, particularly with IC, and to explore its possible role in restenosis after lower limb revascularization.

The Platelet Aggregation Inhibition Activity of Polyphenols can be mediated by 67kda Laminin Receptor: A New Therapeutic Strategy For the Treatment of Venous Thromboembolism.

Thrombotic disease is still a major killer. Aspirin, Ticagrelor, Clopidogrel, etc. are the most widely used conventional antiplatelet drugs. The significant number of patients who are resistant to this drug shows a poor outcome. Developing a new antiplatelet agent with a stable antiplatelet effect and minimal bleeding risk is required for a patient who is resistant to antiplatelet drugs. Protein-ligand docking was performed using Autodock Vina 1.1.2 to study the interaction of 67LR with different Polyphenols. Among the 18 polyphenols, thearubigin has the highest binding affinity towards 67LR and gallic acid shows the lowest binding affinity. Among the 18 molecules, the top 10 molecules from the highest to lowest binding affinity range from-10.6 (thearubigin) to -6.5 (Epigallocatechin). Polyphenols may inhibit platelet aggregation through 67 LR and can be an alternative treatment for Thrombotic Disease. Moreover, it will be interesting to know whether polyphenols interfere with the same pathways as aspirin and clopidogrel. Effective polyphenols could help prototype the compound development of novel antiplatelet agents.