31 Clinical Trials for Various Conditions
To compare the effects of IV iron versus placebo (saline) injection on arterial oxygen saturation, submaximal exercise responses, and 2-mile treadmill time-trial performance during acute exposure to hypobaric hypoxia (430 mmHg, simulating \~4800m) assessed 1 and 14 days after treatment. Primary Hypothesis 1: IV iron treatment will improve arterial oxygen saturation at rest and during exercise in acute hypobaric hypoxia and this effect will persist for 2 weeks Primary Hypothesis 2) IV iron treatment will improve 2-mile treadmill time trial performance in acute hypobaric hypoxia and this effect will persist for 2 weeks
The goal of this study is to learn if the probiotic SLAB51 (Sivomixx800®) works to enhance acclimatization to high altitude in humans. The main questions it aims to answer are: Does SLAB51 improve oxygen saturation during high-altitude exposure? Researchers will compare SLAB51 to a placebo (a substance that contains no probiotic) to see if SLAB51 works to enhance high-altitude acclimatization. Participants will: Take SLAB51 or a placebo three times daily during two separate three-night acclimatization periods at high altitude, spaced at least six weeks apart. Complete baseline measurements at sea level. Visit the high-altitude Barcroft Station (3,801 m) at the University of California White Mountain Research Center for physiological measurements and assessments. Undergo assessments including oxygen saturation, ventilation, heart rate, blood pressure, sleep studies, cognitive assessments, exercise capacity, Acute Mountain Sickness scores, and provide blood, fecal, and urine samples for advanced analyses.
To understand alterations in glycogen and molecular regulation of skeletal muscle glucose uptake, glycogen synthesis, and muscle protein recovery when consuming CHO (glucose) or CHO+PRO (glucose + whey) post-exercise during unacclimatized high altitude exposure, randomized crossover double blinded studies will be conducted in the hypobaric/hypoxic chamber at USARIEM Table 1. Briefly, the study consists of a 2 day baseline period at SL followed by two, 3 day trial periods (with the 3rd day being a testing day) at HA. The baseline is separated from trial 1 for a least a day, and trial 1 \& 2 separated by at least 4 days. Volunteers will consume CHO (glucose) or CHO+PRO (glucose + whey) drinks post-exercise during unacclimatized high altitude exposure during the two trial periods. The order of the drinks will be randomized (using a random number generator such as randomizer.org) and kept by a study staff not directly involved in data collection to maintain blinding.
Apparent hypoxia-induced insulin insensitivity along with alterations in glucose kinetics suggests reduction in glucose uptake by the peripheral tissue is a primary factor contributing to reductions in exogenous glucose oxidation at HA. As such, the primary objective of this study is to determine the ability of an insulin sensitizer (Pioglitazone, PIO) to enhance exogenous glucose oxidation and metabolic clearance rate during metabolically-matched, steady-state exercise during acute HA exposure compared to placebo (PLA) in native lowlanders. Secondary objective of this study will be to assess the impact of PIO on markers of inflammation and iron status compared to PLA. This randomized crossover placebo control double blinded study will examine substrate oxidation and glucose kinetic responses to ingesting supplemental carbohydrate (glucose) during metabolically-matched, steady-state exercise with acute (\~5 h) exposure to HA (460 mmHg, or 4300m, barometric pressure similar to Pike's Peak) after receiving PIO (HA+PIO), or after receiving a matched placebo (HA+PLA). Eight healthy, recreationally active males between the ages of 18-39 yrs will be required to complete this study. Following a 4 day glycogen normalization period receiving PIO or PLA daily, volunteers will complete two 80-min trials, performing metabolically-matched, steady-state aerobic (same absolute workload corresponding to \~55 ± 5% of V̇O2peak at HA) exercise on a treadmill, and consuming 145 g of glucose (1.8 g/min); one trial with HA+PIO and the other with HA+PLA. A dual glucose tracer (13C-glucose oral ingestion and \[6,6-2H2\]-glucose primed, continuous infusion) technique and indirect calorimetry will be used to selectively analyze endogenous and exogenous glucose oxidation, as well as glucose rate of appearance (Ra), disappearance (Rd) and metabolic clearance rate (MCR). Serial blood samples will be collected during each trial to assess endocrine and circulating substrate responses to exercise, carbohydrate, and hypoxia with or without PIO. All trials will occur at the same time of day in the USARIEM hypobaric/hypoxic chamber and be separated by a minimum 10-d washout period. The primary risks associated with this study include those associated with acute hypobaric hypoxia, exercise, and blood sampling.
The aim of this randomized, double-blind study is to determine whether erythropoietin (Procrit) and acetazolamide: 1) mitigates altitude-induced decrements in performance at moderate altitude (3,000 m) and 2) mitigates altitude-induced decrements in performance and reduce acute mountain sickness during prolonged exposure to high altitude (4,300 m; 15 days). Volunteers will complete 5 study phases: Phase 1) sea level baseline testing and a moderate altitude exposure; Phase 2) 4 week study intervention - randomly assigned to receive erythropoietin or placebo); Phase 3) 3 1/2 days of acetazolamide and a moderate altitude exposure; Phase 4) high altitude acclimatization - 15 days at Pikes Peak; and Phase 5) two week deacclimatization. Test battery include VO2peak, 3.2 km treadmill time trial, measures of gas exchange and ventilation during rest and exercise, and blood collection.
The primary objective is to evaluate the efficacy of continuous positive pressure on resolution of high-altitude pulmonary edema vs high flow oxygen. The secondary objective is to derive an incidence of high-altitude pulmonary edema based on the elevation and timing from which the subject arrives. Additionally, in a convenience sample of the base study population, an ultrasound evaluation for the presence of B lines in the lungs will be conducted after 2 hours.
The aim of this randomized, crossover clinical trial is to determine the efficacy of a gut microbiota-targeted nutritional intervention containing a blend of fermentable fibers and polyphenols (FP) for mitigating increases in GI permeability, and decrements in immune function and neuropsychologic performance following rapid ascent to simulated high altitude. Fifteen healthy young adults will participate in each of three study phases that include a 14-day supplementation period in which participants will consume 1 of 2 supplement bars: placebo (PL, will be consumed during 2 phases) and FP supplementation (will be consumed during one phase only). During the final 2-d of each phase, participants will live in a hypobaric chamber under sea level or high altitude conditions.
Recent studies have reported that oxidation of exogenous carbohydrate is reduced under acute hypobaric hypoxic (high altitude; HA) conditions compared to normoxia (sea level; SL) in native lowlanders. However, the mechanisms by which HA suppresses exogenous carbohydrate oxidation are not known. This study will seek to confirm that acute HA exposure decreases exogenous carbohydrate oxidation during steady-state aerobic exercise compared to SL, and explore if the mechanism inhibiting plasma glucose uptake is insulin dependent or independent.
Individuals traveling to altitudes above 8,000 feet may suffer from impaired exercise and cognitive performance, and acute mountain sickness (AMS). Decreased barometric pressure, which leads to low blood oxygen levels, is the primary cause of these disorders. Symptoms of AMS are characterized by headache, nausea, vomiting, dizziness, fatigue, and difficulty sleeping. The goal of this research is to identify whether Respiratory Muscle Training will improve physical and cognitive performance, and reduce the symptoms of AMS, at simulated high altitude.
The overall goal of this study is to detect preclinical signs of HAPE by lung ultrasonography and evaluate the effectiveness of acetazolamide at decreasing pulmonary edema by using ultrasound.
Acute Mountain Sickness (AMS) is a well-documented syndrome that affects 42% of non-acclimatized individuals traveling to altitudes above 10,000 feet. Decreased barometric pressure, which leads to low blood oxygen levels, is the primary casual factor of AMS. Symptoms of AMS are characterized by headache, nausea, vomiting, dizziness, fatigue and difficultly sleeping. Moreover, when people travel to high altitude, cognitive performance and endurance exercise capacity are impaired. Therefore, the goal of this research is to identify effective pharmacological agents that will help reduce the symptoms of AMS and improve physical and cognitive performance at high altitude. The investigators will study the efficacy of the dietary supplement, quercetin, the drugs nifedipine (extended release) and methazolamide taken together, the drug metformin, and the drug nitrite in reducing symptoms of AMS and improving cognitive and exercise performance at high altitudes.
Pregnancy elicits adaptive changes in uteroplacental blood flow, which are altered at high altitude and may contribute to the observed 3-fold increase in intrauterine growth restriction (IUGR) and preeclampsia (PreE). The investigators propose to collect myometrial, cord blood, and placental tissue samples from women at high altitude (Summit County) and low altitude (Denver) in Colorado in order to determine if residence at altitude during pregnancy changes the vasoreactivity of myometrial arteries (MA). If altered MA vasoreactivity is found, further studies may be able to link these changes to the increased rates of PreE and IUGR at altitude and contribute to the understanding of these two disorders.
The purpose of this study is to assess the performance of the Dario Blood Glucose Monitor (BGMS), at elevated altitudes, by obtaining whole blood fingerstick samples from individuals and analyzing the blood on the Dario Blood Glucose Monitor (BGMS) and comparing the readings to readings obtained from the YSI 2300 STAT Plus glucose analyzer.
Ibuprofen is often taken by travelers to high altitude to treat the symptoms of acute mountain sickness such as headache and malaise. However, the blunting of inflammation by ibuprofen may slow the process of acclimatization to altitude, which relies on mediators of inflammation for adjustments in breathing. The study randomizes healthy subjects to receive ibuprofen or placebo and then ascend to altitude (12,500 feet). Blood cytokines and non-invasive measurements of blood and tissue oxygen levels will be made for 48 hours at altitude. The hypothesis being tested is that subjects receiving ibuprofen will have lower blood and tissue oxygen levels after 48 hours at altitude than will placebo subjects.
During ascent to high altitude there is a physiologic response to hypoxia that results in an elevated pulmonary arterial pressure associated with decreased exercise performance, altitude-induced pulmonary hypertension, and high altitude pulmonary edema (HAPE). Riociguat is a novel agent from Bayer Pharmaceuticals that has already demonstrated effectiveness in the treatment of pulmonary hypertension, and it may prove to be beneficial in cases of altitude-induced pulmonary hypertension or HAPE. This research study, composed of 20 healthy volunteers ages 18-40 years, will attempt to mimic the decreased oxygen supply and elevated pulmonary artery pressures found in conditions of high altitude, allowing observation of the effects of riociguat and exercise on pulmonary arterial pressure, arterial oxygenation, and exercise performance. Prior to entering the hypobaric chamber, subjects will have radial arterial lines and pulmonary artery catheters placed to obtain arterial and pulmonary artery pressure measurements. Subjects will then enter the hypobaric chamber and perform exercise tolerance tests at a simulated altitude of 15,000 feet on an electrically braked ergometer (exercise bike) before and after administration of riociguat. If, after administration of riociguat and exposure to a simulated altitude of 15,000 feet, the exercise performance is improved and observed pulmonary artery pressures are lower than those measurements seen prior to administration of riociguat, this could lead to development of a prophylactic and/or treatment strategy for HAPE and high-altitude pulmonary hypertension. Statistical analysis will compare the variables of pulmonary artery pressure, radial arterial pressure, ventilation rate, cardiac output, PaO2, and work rate at exhaustion before and after administration of the drug riociguat. The investigator's hypothesis is that riociguat will decrease pulmonary artery pressure and improve gas exchange and exercise performance at altitude.
This is a phase 4, randomized, double-blinded interventional trial comparing alternative doses of Acetazolamide for the prevention of High Altitude Illness.
This study is being conducted to determine the effectiveness of using two FDA approved medications in concert to reduce the likelihood of sickness due to low oxygen levels and to reduce the decrement in physical performance at higher elevations. The investigators hypothesize that this drug combination will reduce the symptoms of acute mountain sickness and improve exercise performance at high altitude compared to placebo.
Acute exposure of the unacclimatized human body to high altitude leads to health complications, such as loss of exercise performance capacity and fatigue. The investigators have found that the combination of the xanthine drug theophylline and the endothelin receptor antagonist ambrisentan improves the exercise performance capacity of rats under simulated high altitude. In young, healthy human volunteers, this combination of drugs has not increase toxicity over the single compounds under sea-level conditions. The aim of this study is to test whether the combination of theophylline, supplied as its more soluble formulation aminophylline, and ambrisentan, are also safe to take under simulated high altitude of 4,267 meters, under both resting and exercising conditions. The study also aims to test whether this drug combination improves exercise capacity in humans. In this study, human subjects will be randomized to one of four treatment sequences and receive the same study drug(s) throughout all procedures. The study consists of an initial exercise test, followed by two cycles of drug testing at simulated high altitude: Cycle 1 - resting subjects receiving study drug at simulated altitude and continually monitored for safety with pharmacodynamic and pharmacokinetic assessments; and Cycle 2, the same as Cycle 1, with the addition of exercise testing. It is hypothesized that the combination of aminophylline and ambrisentan is not only safe under simulated high altitude, but also improves exercise performance capacity, in comparison with placebo.
The objective of this study is to determine if single dose administration of inhaled iloprost will reduce pulmonary artery pressure, reduce hypoxic pulmonary vasoconstriction and improve arterial oxygenation at rest and during exercise at high altitude.
This study is to determine whether bosentan will alter exercise capacity after rapid ascent to high altitude. We hypothesize that bosentan administration will improve arterial oxygenation and exercise capacity.
This is a Phase I, three period, two sequence, open-label, randomized, crossover study, with the primary objective of testing the safety and tolerability of combined oral doses of aminophylline and ambrisentan in healthy human subjects. The secondary objective is to assess the pharmacokinetic profiles of theophylline (aminophylline) and ambrisentan when administered alone or in combination. It is hypothesized that the combination of these drugs is generally safe, and that no drug interaction can be observed.
The main purpose of this study is to determine if a drug (acetyl-cysteine or ACCY) can increase the amount of oxygen in your body at a high altitude of 11,500 feet. ACCY is approved by the Food and Drug Administration (FDA) as a treatment or antidote for Tylenol overdoses. Other forms of ACCY are also sold over-the-counter as nutritional supplements. In this study, the FDA-approved form of ACCY will be used "off-label" (meaning in a way not approved by the FDA). This study is being conducted by researchers from the United States Army Research Institute of Environmental Medicine (USARIEM). The study will take place in the Altitude Chamber located in the basement of USARIEM. A total of approximately 30 volunteers (men and women, military and civilians) will take part in the study. They can expect to be in the study for a minimum of a few hours each day for two weeks. The investigators hypothesize that ACCY will improve ventilation and oxygenation while at altitude.
This research will evaluate nutrition requirements for missions at high altitude (i.e. \>7800 feet above sea level) and the information obtained can be used to optimize nutrient content specifications for combat rations. The objectives are: 1. Determine whether loss of lean body mass resulting from negative calorie balance over a 22-d period at high altitude can be prevented by increasing dietary protein intake. 2. Determine the efficacy of carbohydrate (glucose and fructose) supplementation on aerobic exercise performance at sea level, acute exposure to high altitude, and in response to 22-d period of negative calorie balance at high altitude. 3. Determine cognitive function, sleep patterns, and behavioral responses to high altitude and underfeeding. 4. Determine appetite and eating behavior in response to high altitude and sustained underfeeding. 5. Examine the effects of high altitude, negative calorie balance, dietary intake manipulations on gut health.
The current protocol is composed of two studies. The first study is designed to carefully evaluate the safety of high-dose salmeterol/fluticasone (Advair HFA) versus placebo (hydrofluoroalkane, HFA) administration over 7 days, as well as the efficacy of the study drug to increase exercise performance, in healthy individuals exercising under hypoxic, simulated high-altitude conditions (Phase 1/2a study). The second study will examine sensitive measures of cardiopulmonary function using invasive cardiopulmonary testing, in both HAPE-sensitive and HAPE-resistant individuals, to assess the potential efficacy of salmeterol/fluticasone to prevent pulmonary edema and to enhance exercise capacity (Phase 2a) in these individuals.
This research study will evaluate changes in resting metabolic rate, appetite, and heart rate variability following overnight exposure (8 h/night) to normobaric hypoxia (NH) or normobaric normoxic (NN). In randomized order, participants will sleep one night in NH conditions (\~15% oxygen; achieved with nitrogen dilution, equivalent to \~8500 feet elevation) and another night in NN (control) conditions (\~20% oxygen; achieved with nitrogen dilution, equivalent to \~1000 feet elevation).
Low oxygen at altitude causes pauses in breathing during sleep, called central sleep apnea. Central sleep apnea causes repeated awakenings and poor sleep. Low oxygen itself and the induced oxidative stress can damage mental function which is likely worsened by poor sleep. Reduced mental function due to low oxygen can pose a serious danger to mountain climbers. However there is also mounting evidence that even in populations of people that live at high altitudes and are considered adapted, low oxygen contributes to reductions in learning and memory. Therefore there is a serious need for treatments which may improve sleep, control of breathing and mental function during low oxygen.Therefore this study aims to determine how melatonin effects control of breathing, sleep and mental performance during exposure to low oxygen.
The proposed study is a prospective, randomized, double-blind, placebo-controlled clinical trial evaluating ibuprofen and placebo for the prevention of neurological forms of altitude illness \[including high altitude headache (HAH), acute mountain sickness (AMS), high altitude cerebral edema (HACE), and an emerging concept of High Altitude Anxiety\]. The study will take place in the spring and summer of 2012 at the Marine Corps Mountain Warfare Training Center in the Eastern Sierras near Bridgeport, California. US Marines from near sea level will participate in battalion-level training exercises at between 8,500-11,500 Feet, where some altitude illness is expected. Concurrent measures used to determine objective markers of altitude illness, such that validated clinical scales, rapid cognitive screening tests, will inform us of symptoms of altitude illness.
This safety study is the first in a series of studies testing the application of the combination of aminophylline and methazolamide.
Hypobaric hypoxia (decreased oxygen supply to body tissues due to low atmospheric pressure) caused by exposure to high altitude disrupts sleep. Sleep deprivation is associated with degraded post-sleep performance of neurobehavioral tasks. The lowest altitude at which sleep and/or post-sleep performance are affected is not known. The study hypothesis is that sleep and/or post-sleep performance of neurobehavioral tasks will occur due to hypobaric hypoxia at altitudes of 8,000 or less.
The purpose of this study is to look at how a reduction in oxygen levels (hypoxia) influences insulin sensitivity and carbohydrate metabolism. It is expected that 10 nights of exposure to moderate hypoxia (\~ 15% O2, similar to conditions at an altitude of \~7500 feet) will improve glucose metabolism.