20 Clinical Trials for Various Conditions
The purpose of this study is to understand how the drug rivaroxaban improves symptoms associated with peripheral artery disease.
Open heart surgery requires the use of a cardiopulmonary bypass (CPB) circuit. As blood flows across the artificial surfaces of the CPB circuit, platelets are activated and consumed. This activation results in a profound inflammatory reaction and need for transfusion. This reaction is intensified in younger, smaller patients undergoing longer, more complex open heart surgery. Nitric oxide is naturally released by vascular endothelial surfaces and acts as a signaling molecule which prevents platelet activation. The investigators hypothesize that the addition of the nitric oxide to the sweep gas of the oxygenator during cardiopulmonary bypass surgery will replace this natural endothelial function and thus prevent platelet activation and consumption. The investigators plan to test this hypothesis with a pilot double blinded, randomized trial of 40 patients less than a year of age undergoing cardiac surgery requiring CPB.
The primary goal is to assess the impact of Evolocumab therapy on platelet function of familial hypercholesterolemia (FH) patients in a randomized, double blind study. Evolocumab is a humanized monoclonal antibody that targets circulating PCSK9, increases hepatic LDL receptor, decreases plasma LDL cholesterol and reduces risk of cardiovascular events. Evolocumab (brand name Rapatha) has been approved by FDA along with diet and maximally tolerated statin therapy in adults with FH or atherosclerotic heart or blood vessel problems, who need additional lowering of LDL cholesterol. The secondary goal is to determine if platelet activation or the response to Evolocumab therapy is modified by rs3184504 polymorphism. The investigators believe that these investigations will complement ongoing studies to demonstrate that Evolocumab reduces athero-thrombotic risk and aid the decision-making as to whether Evolocumab can reduce the atherothrombotic risk in acute coronary syndrome (ACS) patients.
This will be a randomized, double-blinded, three-period crossover study of platelet activation and aggregation in 30 non-smoking healthy volunteers comparing chlorthalidone (CTD), hydrochlorothiazide (HCTZ), and aspirin (ASA; active control). The study hypothesis is that CTD has different effects on platelet activation and aggregation than HCTZ.
The purpose of this study is to determine if aspirin taken by firefighters prevents platelets from becoming sticky when body temperature rises during work in protective clothing.
Thrombin is the most potent activator of platelets, and platelet activation is a hallmark of thrombosis. Coronary artery disease (CAD) is the major cause of mortality and morbidity in the United States and other industrialized countries, and thrombotic sequelae are the key cause of death in diabetes. The accumulation of thrombin at sites of vascular injury provides one of the major mechanisms of recruiting platelets into a hemostatic plug. Thrombin works by activation of the G protein-coupled protease activated receptors PAR1 and PAR4 on human platelets to initiate signaling cascades leading to increases in \[Ca\]i, secretion of autocrine activators, trafficking of adhesion molecules to the plasma membrane, and shape change, which all promote platelet aggregation. The thrombin receptors work in a progressive manner, with PAR1 activated at low thrombin concentrations, and PAR4 recruited at higher thrombin concentrations. As direct thrombin inhibitors become widely used in clinical practice, it is important to assess their effects on vascular function. Our hypothesis is that PAR1 and PAR4 do not signal through the same G protein pathways, and that PAR4 is not a strong platelet agonist. To investigate this hypothesis, the investigators will study the G protein pathways downstream of PAR4, and assess ex-vivo platelet responsiveness to thrombin, PAR1, and PAR4 agonist peptides, both in normal human subjects, and along the stages of pathology, from patients with stable angina as well as unstable angina who are undergoing angioplasty. Similarly, the investigators will examine platelet function in patients with metabolic syndrome as well as diabetes, along the continuum from insulin resistance to full-blown disease. These studies will provide deeper insight into the G protein pathways used by PARs. They will elucidate the contribution of PAR receptors to normal platelet function as well as the abnormal platelet activation in thrombotic states. The long term goal is to understand the implications for PAR receptors as therapeutic targets for anti-platelet therapies that may carry less bleeding risk.
In this study the focus will be on correlating the levels of platelet activation markers (proteins that are released when blood cells are activated)to the duration of cardiopulmonary bypass, temperature during cardiopulmonary bypass and the weight of the patient.
The purpose of this study is to test a novel diagnostic immunoassay of platelet function and compare it to the current gold standard platelet function assay by testing the response to aspirin and clopidogrel in a group of healthy volunteers and severely obese individuals and comparing the accuracy of the two tests. The secondary goals will be to evaluate the pharmacodynamic parameters of the antiplatelet agents across the two testing modalities and refine the cutoffs used for the novel assay.
In this blinded prospective randomized control trial the researchers will investigate the impact of cutaneous vagal nerve stimulation on surgical conditions in patients undergoing functional and ascorbic sinus surgery (FESS). The device is an externally placed vagal nerve stimulator. The device will be applied to participants after consent and induction of anesthesia. The study team will open the randomization envelope and if the participant is assigned to stimulation the device will be turned on. In the case that the participant is assigned to the control arm, the device will be set to sham. The device will remain on for 30 minutes and removed before entering the OR. Device will be reinserted in the recovery room for another 30 minutes.
The purpose is to conduct a dietary intervention study in which human participants will consume beverages sweetened with erythritol or aspartame, each for 2 weeks, in a randomized crossover design
MitoQ is commercially available as a dietary supplement and it has been tested as a potential drug in other diseases, but it has never been tested in patients with sickle cell disease. The goal of this research is to study if MitoQ, a molecule that works as an antioxidant by removing potentially damaging agents in a living organism, improves platelet function in patients with sickle cell disease (SCD).
The purpose of this research study is to understand if platelets in the blood become more active during cancer and specially advanced stages of cancer, in the future the investigators want to see if reducing platelet activity can improve survival in advanced cancer.
The investigators hypothesize that increasing plasma nitrite using dietary nitrate will improve platelet function and red cell deformability and decrease MCHC in patients with sickle cell disease. The investigators will test this hypothesis through administration of daily intake of beetroot juice (Unbeetable - Performance Drink) to patients with sickle cell disease for 28 days. The investigators will evaluate the safety of daily beet root juice intake in patients with sickle cell disease. In addition, the investigators will measure MCHC, red cell deformability, and platelet function (activation and aggregation) in response to daily intake of beet root juice in this patient population.
The central hypothesis for this work is that platelet - leukocyte interactions play a critical role in the pathogenesis of acute ischemic events. The primary objective of the study is to determine if early, high-dose administration of the HMG-CoA reductase inhibitor rosuvastatin in the setting of acute coronary syndrome and percutaneous coronary intervention exerts beneficial vascular effects by reducing platelet - leukocyte interactions.
Sickle cell disease (SCD) is often referred to as a hypercoagulable state. However, the contribution of coagulation activation to the pathogenesis of SCD remains uncertain. Pulmonary hypertension (PHT) is a common complication associated with significant morbidity and mortality. Autopsy studies of SCD patients with PHT show evidence of in situ thrombosis involving pulmonary vessels, similar to findings in non-sickle cell patients with PHT. Anticoagulation has been reported to be of benefit in non-sickle cell patients with PHT. With the evidence of increased coagulation activation in SCD, PHT represents a clinical endpoint that may be used to evaluate the contribution of coagulation activation to the pathophysiology of SCD. The investigators hypothesize that increased thrombin generation, as well as platelet activation are central to the pathophysiology of SCD and contribute to the occurrence of several SCD-related complications, including PHT. As a consequence, treatment modalities that down-regulate thrombin generation would be expected to delay the progression of PHT and result in improved survival in patients with SCD.
Aspirin has been shown to reduce cardiovascular events in at risk individuals. Elucidation of mechanisms of aspirin resistance and a possible loss of effect of aspirin over time with chronic aspirin treatment necessitate a more precise method of measuring the "release phase" of platelet activation, including the release of dense granules from platelets.
The purpose of this study is to evaluate alterations in sympathetic tone in patients with major depression with and without ischemic heart disease and then to reevaluate these patients after 8 treatments with electroconvulsive therapy(ECT). We expect to support the hypothesis that HRV are pathophysiologically associated with the state of major depression. We hypothesize the following: 1. Heart rate variability (HRV) will be decreased prior to treatment of depression in comparison to post-treatment measures of HRV. 2. After 8 treatments with ECT, HRV will be increased under basal conditions.
Platelet activation has been associated with bad events like heart attack and stroke. There are a variety of platelet activators that regulate how active a platelet is. We are interested in Protease-activated receptors (PAR)-1. We are currently studying PAR-1 activation in persons with severe peripheral artery disease. We seek, through this project, to understand PAR-1 activation in persons without peripheral artery disease. As many patients with peripheral artery disease have diabetes, we will also evaluate PAR-1 activation in persons with type 2 diabetes. In addition we will assess the impact of the glucagon-like peptide (GLP)-1 signaling pathway on platelet activation. Levels of platelet activation will be determined using platelet aggregation experiments and assessment of platelet-monocyte aggregates in peripheral blood.
Advances in antiretroviral therapy (ART) have resulted in increased survival of the HIV-infected population; however, this gain in longevity is associated with an increased risk of cardiovascular disease (CVD). Although ART and traditional risk factors contribute to CVD in this population, heightened markers of immune activation, inflammation, and coagulation independently predict morbidity and mortality, suggesting that dysregulation of these systems plays a significant role in the increased risk of CVD. The investigators believe that platelet activation is an important driver in HIV-associated immune activation, inflammation, and coagulation, leading to an increased CVD pathophysiology and risk. Platelets initiate thrombus formation and also play a key role in vascular inflammation by releasing pro-inflammatory mediators and cross-talking with other relevant cell types including leukocytes. Researchers have described platelet hyperreactivity in chronic HIV infection. Importantly, the investigators demonstrated that one week of anti-platelet therapy (aspirin) decreased platelet activation and immune activation, with an improved trend in inflammation and immune parameters. The overall hypothesis is that platelet activation is a major driver of immune activation, inflammation, and thrombosis in ART-treated HIV infected patients. The purpose of the proposed proof-of-concept study is to understand the mechanism(s) by which anti-platelet therapy improves immune and inflammatory parameters in chronic HIV infection. To test this, the immune modulating and anti-inflammatory effects of 24 weeks of the anti-platelet drug aspirin as compared to the anti-platelet drug clopidogrel will be evaluated. Given their different mechanisms of action and inhibitory potency, the investigators can differentiate whether the potential benefits are mediated via inhibition of arachidonic acid (aspirin) or inhibition of ADP (clopidogrel) or by the antithrombotic activity. A secondary goal is to perform multidimensional assays of platelet activity and thrombogenicity alongside immune activation assays and careful assessments of traditional risk factors and medication regimens, to understand which parameters are highly associated with thrombogenicity.
The purpose of this study is to compare the effect of dark chocolate with green tea in healthy subjects on clot formation (platelet activity) cholesterol profile and markers of inflammation in two groups. The first group will be on a regimen of dark chocolate, and the second group will be on a regimen of green tea. Clinical outcomes will be determined after seven days of each treatment and both groups will undergo both treatments subsequently and serve as their own control. The hypothesis is that both green tea and dark chocolate will reduce platelet activity and reduce LDL, hsCRP and increase HDL.