25 Clinical Trials for Various Conditions
The goal of this mechanistic clinical trial is to learn about the effects of medications called soluble guanylyl cyclase stimulators on vascular function and markers of kidney and brain injury in patients having heart surgery. The main questions it aims to answer are: 1. Does soluble guanylyl cyclase stimulation improve blood vessel function compared to placebo? 2. Does soluble guanylyl cyclase stimulation decrease markers of kidney injury and brain injury compared to placebo? Participants will be randomized to a soluble guanylyl cyclase stimulator called vericiguat or placebo, and researchers will compare vascular function and markers of brain and kidney injury to see if vericiguat improves vascular function and reduces markers of injury. This will provide important information to determine the underlying reasons that patients have some kidney and brain function problems after having heart surgery.
Cannabidiol, or CBD, is an over-the-counter "nutraceutical" that is more commonly being used by healthy adults for pain management, recovery from strenuous exercise, and general wellness. However, little research exists on the effects of CBD in otherwise healthy individuals. This study uses iontophoresis, a common technique used in physical therapy, to determine the effectiveness of topical CBD in lessening the reflex increased cutaneous vascular conductance response to stimulation of the skin.
The goal is to characterize vascular reactivity and cardiac pulsatility of normal appearing white matter in patients with CCM during hypercarbia/hypocarbia using quantitative real-time high-speed multi-echo fMRI to develop prognostic biomarkers for CCM formation
1. Quantitative validation of non-contact oxygenation imaging by the CWC imaging system 2. Quantitative validation of non-contact vascular function imaging by the CWC imaging system 3. Evaluation of the clinical usability of the CWC imaging system for further technology development and engineering improvement
Pioglitazone decreases oxidative load, inflammatory end points and improves vascular reactivity in obese patients in a dose dependent manner and that this effect is independent of its glucose lowering effects.
The purpose of this study is to determine whether combination therapy with sildenafil and losartan can improve function and exercise tolerance in patients with idiopathic pulmonary fibrosis.
This research is studying how Vitamin D may affect blood vessels reaction to stress and blood levels of substances that may increase blockages in the blood vessels in chronic kidney disease (CKD) patients. Blood vessel health is worsened in CKD and some studies have shown that Vitamin D improves blood vessel health. The type of Vitamin D being used in this study (paricalcitol) is Food and Drug Administration (FDA) approved to treat high parathyroid hormone levels. The purpose of this study is to find out if paricalcitol has other benefits beyond its ability to lower parathyroid hormone levels such as improving the blood vessels reaction to stress and decreasing blood levels of substances that may increase blockages in the blood vessels.
Metabolic Syndrome is a highly prevalent condition that is comprised of several major clustering factors that increase the risk for developing cardiovascular disease. Diffuse Optical Spectroscopy is a non-invasively measure can show changes in the microvasculature of human. Diffuse Optical Spectroscopy measures the optical absorption and scattering properties of near-infrared light in tissues such as muscle in order to quantify the absolute concentration of oxygenated and deoxygenated hemoglobin, water, and lipids. It provides quantitative and functional information on the microvasculature related to tissue perfusion, metabolic changes, and indicators of tissue damage.
This is a study of the effects of 3 oz almonds added daily to a National Cholesterol Education Program Therapeutic Lifestyle Changes (TLC) diet in improving endothelial function in patients with Coronary Artery Disease. The study seeks to determine if these effects are mediated via an increase in Nitric Oxide synthesis and reductions in dyslipidemia and systemic inflammation. Vascular reactivity will be assessed via flow mediated dilation with endothelium-independent and hyperemic flow measured in the right brachial artery by non-invasive 2-dimensional and Doppler ultrasound. Serum will be collected and analyzed for biomarkers of dyslipidemia, inflammation, endothelial function, vascular reactivity and oxidative stress.
The purpose of this study is to compare the effects of oral versus patch administration of hormonal contraception on hormone sensitive proteins such as lipoproteins, clotting factors and inflammatory proteins as well as blood sugar and insulin levels, antioxidant status and flow-mediated dilation of arm and forearm vessels. The hypothesis is that oral administration of contraceptive hormones will result in higher plasma levels of estrogen sensitive proteins originating from the liver while patch administration of contraceptive hormones will result in greater systemic effects of estrogen on vascular reactivity and antioxidant status.
The metabolic syndrome consists of five concurrent conditions which increase risk of heart disease, stroke, and diabetes. Persons with the metabolic syndrome usually have high triglyceride and low HDL levels and are overweight. Low fat, high carbohydrate diets may not provide the same cholesterol-lowering benefits to obese individuals as they do to non-obese individuals. The purpose of this study is to compare the effects of a low fat, high carbohydrate diet versus a moderate fat, moderate carbohydrate diet on the heart, blood vessels, and cholesterol levels in individuals with metabolic syndrome.
The aim of this study is to explore the significance of the Lys:Arg ratio on responses of lipids and lipoprotein concentrations to dietary proteins and to evaluate the effects of dietary Lys:Arg on cardiovascular disease risk factors and endothelial function.
To examine vascular reactivity and inflammatory biomarkers via quantitative magnetic resonance imaging (MRI) and blood serum, respectively, in a crossover study where active vapers (electronic cigarette users) and smokers will undergo three separate acute exposure-episodes of electronic cigarette +/- nicotine and tobacco-cig. The MRI exams and blood draws will be performed pre- and post-exposure. The results will be compared against baseline values derived from a group of non-smokers/non-vapers, who will also undergo a blood draw and MRI.
The purpose of this study is to evaluate the effect of atorvastatin on brain vessel reactivity and with it on blood flow in people with mild cognitive impairment.
The purpose of this research study is to better understand how blood flow and metabolism are different between normal controls and patients with disease. The investigators will examine brain blood flow and metabolism using magnetic resonance imaging (MRI). The brain's blood vessels expand and constrict to regulate blood flow based on the brain's needs. The amount of expanding and contracting the blood vessels can do varies by age. The brain's blood flow changes in small ways during everyday activities, such as normal brain growth, exercise, or deep concentration. Significant illness or physiologic stress may increase the brain's metabolic demand or cause other bigger changes in blood flow. If blood vessels are not able to expand to give more blood flow when metabolic demand is high, the brain may not get all of the oxygen it needs. In less extreme circumstances, not having as much oxygen as it wants may cause the brain to grow and develop more slowly than it should. One way to test the ability of the blood vessels to expand is by measuring blood flow while breathing in carbon dioxide (CO2). CO2 causes blood vessels in the brain to dilate without increasing brain metabolism. The study team will use a special mask to control the amount of oxygen and carbon dioxide patients breath in so that we can study how their brain reacts to these changes. This device designed to simulate carbon dioxide levels achieved by a breath-hold and target the concentration of carbon dioxide in the blood in breathing patients. The device captures exhaled gas and provides an admixture of fresh gas and neutral/expired gas to target different carbon dioxide levels while maintaining a fixed oxygen level. The study team will obtain MRI images of the brain while the subjects are breathing air controlled by the device.
The investigators will recruit and randomize 200 elective cardiac surgery patients to receive physiologic oxygenation (normoxia) or hyper-oxygenation (hyperoxia) during surgery to test the hypothesis that intraoperative physiologic oxygenation decreases the generation of reactive oxygen species, oxidative damage, and postoperative organ injury compared to hyper-oxygenation.
In people with the metabolic syndrome, the investigators hypothesize that administration of a single 300 mg dose of a grape seed extract (GSE) will reduce insulin resistance (how well cells in the body can take up and use glucose), oxidative stress, and the amount of oxidized LDL in the blood during a 24 hour period. These measurements will be assessed at hourly intervals during the 24 hour study day protocol. Additionally, the investigators hypothesize that daily administration of 300 mg of GSE for 30 days will decrease baseline insulin resistance, oxidative stress, and the level of oxidized LDL in the blood.
It is well known that diabetes and excessive or high blood sugars causes blood vessel and blood cell damage. It is also possible, then, that people with pre-diabetes may also start to have blood vessel and blood cell damage as the blood sugars rise from the normal range into the diabetic range. In addition to looking at potential damage, the question is whether or not this damage improves with exercise. This study aims to look at blood vessel and blood cells in three different ways by 1) looking at how the blood vessel responds to "sheer force" (a blood pressure cuff pumped up and then released after a few minutes). This is done by ultrasound. 2) By looking at blood tests such as blood sugar, cholesterol, and inflammation and 3) By looking at certain blood cells in the lab, how long they live and the number of cells left after a certain number of days, and again, if this improves with exercise.
The purpose of this research study is examine the response of the blood vessels in the eye to a light flicker stimulus using the Dynamic Vessel Analyzer (DVA) on two separate days in healthy individuals. The DVA uses an instrument which is used during routine eye examinations. The hypothesis of the study is that the changes in eye's blood vessel will be similar between the two visits; thus establishing reproducibility of the measurements for future comparisons to individuals with stroke or heart disease. In addition, this study will compare the eye's blood vessel responses to responses of the blood vessels in the arm using Doppler ultrasound.
The study is a prospective open label study to examine the effects of oral and intravenous fat load on blood pressure, endothelial function, sympathetic activity, and oxidative stress in obese healthy subjects. Subjects will receive either 8-hour of intravenous or oral fat loads in either low or high doses or normal saline in random order. Blood samples are drawn and vitals are measured before and after the infusions. Endothelial function and plasma glucose and lipid levels are measured to study the effects.
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
This observational study will examine the association of chronic traumatic cerebrovascular injury and cardiovascular risk factors with TBI-related cognitive impairment and vascular dementia. Cerebrovascular, inflammatory, and neurodegenerative blood biomarkers as well as clinical and neuroimaging data
The "hardening of the arteries" observed with aging raises blood pressure and contributes to poor brain blood flow and loss of cognitive function (i.e. attention, memory, solving problems, making decisions). Cognition is the most important determinant of overall health status, quality of life, functional ability and independence in older adulthood. Nutraceutical strategies have received considerable attention as they may improve cardiovascular health with far fewer side effects compared to drugs. In this regard, dairy products are particularly attractive. Higher dairy consumption is associated with lower blood pressure and improved memory in adults. Milk proteins have natural blood pressure lowering effects. Studies conducted in animals have demonstrated that whey protein (a component of milk protein) may also increase artery elasticity. This is important given the strong association between artery elasticity, brain blood flow, and risk for cognitive decline. The investigators propose to conduct a randomized double-blind placebo controlled study comparing the effects of whey protein supplementation or carbohydrate placebo on measures of artery elasticity, brain blood flow, and cognitive function in older adults. Whey protein may be a novel dietary therapy to improve both artery health and brain health in older adults.
This study attempts to test capillary responses to various challenges without the need for iontophoresis (electrical current).
This study will evaluate the effects of NHLBI's employee exercise program, Keep the Beat, on blood vessel function. Damage to blood vessels can cause narrowing of the vessels, resulting in reduced blood flow to parts of the body such as the heart. Stem cells called endothelial progenitor cells, or EPCs, may be able to heal blood vessel damage. Exercise, such as walking on a treadmill, can help move EPCs from the bone marrow where they originate into the blood stream to help heal the damaged blood vessels. The Keep the Beat program encourages NHLBI employees to exercise 15 minutes during the workday and provides exercise facilities to accomplish this. NHLBI employees who have access to NIH exercise facilities may be eligible for this study. Candidates must have no history of heart disease, must not currently be exercising more than 1.5 hours per week and must not have participated in the Keep the Beat program for 3 months prior to entering the study. They are screened with blood tests and blood pressure measurements. Participants undergo the following tests and procedures before beginning the study and 3 months after participating in Keep the Beat: * Blood tests to identify EPCs and their function, measure the level of nitric oxide (a gas produced by healthy blood vessels), and measure C-reactive protein (an inflammatory marker that may be a risk factor for cardiovascular disease). * Brachial artery reactivity study to measure how well the arteries widen. An ultrasound device is placed over the subject's artery just above the elbow. The device measures the size of the artery and the flow of blood through it before and after a pressure cuff is inflated around the forearm. * Treadmill exercise testing to evaluate physical fitness. Subjects exercise on a treadmill for as long as they can. An exercise specialist is present throughout the test. Heart rhythm and oxygen saturation are monitored continuously and blood pressure is measured every 3 minutes.