7 Clinical Trials for Various Conditions
The purpose of this study is to test if temperature homeostasis in football players can be improved by circulating cool, dry air underneath shoulder pads between periods of intense physical activity.
Persons with higher levels of spinal cord injury (above the 6th thoracic vertebrae: Hi-SCI) are unable to maintain their core body temperature (Tcore) within the normal range (97.5-99.7 °F) when exposed to warm environments. Even limited exposure to warm temperatures can cause hyperthermia (Tcore 100.4°F) in Hi-SCI. Mild hyperthermia causes discomfort and impaired thinking, but if unchecked, can lead to permanent damage to the brain, multiple body organ failure, and death. Warm seasonal temperatures have an adverse effect on personal comfort and the ability to participate in daily social activities in persons with Hi-SCI. Interventions addressing this vulnerability to hyperthermia are limited. A self-regulating "smart" cooling vest designed for persons with Hi-SCI, that can effectively dissipate body heat, is a novel and promising strategy to address this problem. Once the current prototype is further developed and bench-tested, the investigators will test the vest in able-bodied participants for safety and comfort. The investigators will then test the vest in participants with Hi-SCI for efficacy. The aim for the cooling vest to minimize the expected increase of 1.1°F in Tcore by at least 50 percent and increase thermal comfort, during a controlled exposure to heat (95°F). If successful, the vest will provide a promising intervention to decrease the adverse impact of warm temperatures on comfort, quality of life, and participation in societal functions for Veterans with Hi-SCI during the warmer seasons.
Persons with higher levels of spinal cord injury (above the 2nd thoracic vertebrae; tetraplegia) are unable to maintain normal core body temperature (Tcore) when exposed to cool environments. In persons with tetraplegia, even limited exposure to cool temperatures may cause Tcore to approach hypothermic values and impair cognitive performance. Conversely, an increase in Tcore from subnormal to normal range may improve cognitive performance. Prior work has shown that cool seasonal temperatures have an adverse effect on personal comfort and the ability to perform vital daily activities of self-care in persons with tetraplegia. Interventions that address the vulnerability to hypothermia are limited. A self-regulating heated vest designed specifically for persons with tetraplegia is a novel and promising strategy to address this problem. By more effectively maintaining Tcore, the vest can decrease the adverse impact of cool temperatures on comfort, quality of life, and performance of vital daily tasks for Veterans with tetraplegia during the cooler seasons.
The ability to maintain normal body temperature (Tcore) is impaired in persons with tetraplegia: subnormal Tcore and vulnerability to hypothermia (\<95 F) have been documented in this population after exposure to even mild environmental temperatures. However, no work to date has addressed the effect of subnormal Tcore on cognitive performance in persons with tetraplegia despite studies with able-bodied (AB) individuals that have documented progressive decline in various aspects of cognitive performance associated with the magnitude of the depression in Tcore. The investigators' study will confirm and extend their initial observations in persons with higher cord lesions who have subnormal Tcore to show that cognitive performance will be improved by raising Tcore to euthermic levels. This improvement should be associated with greater function and independence, reintegration into society, and an improved quality of life. Specific Aims: During exposure to 95 F for up to 120 minutes in the seated position, the investigators' aims are: Primary Specific Aim: To determine if a modest rise in Tcore to euthermic levels has a positive effect on cognitive performance (attention, working memory, processing speed, and executive function) in persons with higher-level spinal cord injury (SCI). Primary Hypothesis: Based on the investigators' pilot data: (1) 80% of persons with SCI will demonstrate an increase of 1 F in Tcore, while none of the AB controls will demonstrate such an increase; (2) 80% of persons with SCI will have an improvement of at least one T-score in Stroop Interference scores (a validated measure of executive function), while none of the AB controls will demonstrate a change in cognitive performance. Secondary Specific Aim: To determine changes in: (1) The average of distal skin temperatures; (2) Sweat rate; and (3) Subjective rating of thermal sensitivity. Secondary Hypothesis: Persons with SCI will have less of a percent change in average distal skin temperatures and sweat rate, and will report blunted ratings of thermal sensitivity compared to that of AB controls.
The ability to maintain normal core body temperature (Tcore = 98.6°F) is impaired in persons with a cervical spinal cord injury (tetraplegia). Despite the known deficits in the ability of persons with spinal cord injury (SCI) to maintain Tcore, and the effects of hypothermia to impair mental function in able-bodied (AB) persons, there has been no work to date addressing these issues in persons with tetraplegia. Primary Aim: To determine if exposure of up to 2 hours to cool temperatures (64°F) causes Tcore to decrease in persons with tetraplegia, and if that decrease is associated with a decrease in cognitive function. Primary Hypotheses: Based on our pilot data: (1) 66% of persons with tetraplegia and none of the matched controls will demonstrate a decline of 1.8°F in Tcore; (2) 80% of persons with tetraplegia and 30% of controls will have a decline of at least one T-score in Stroop Interference scores (a measure of executive function). Secondary Aim: To determine the change in: (1) distal skin temperature, (2) metabolic rate, and (3) thermal sensitivity. Secondary Hypothesis: Persons with tetraplegia will have less of a percent change in average distal skin temperatures and metabolic rate, and report lower thermal sensitivity ratings compared with AB controls. Tertiary Aim: To determine if a 10 mg dose of an approved blood pressure-raising medicine (midodrine hydrochloride) will (1) reduce the decrease in Tcore and (2) prevent or delay the decline in cognitive performance in the group with tetraplegia compared to the exact same procedures performed on the day with no medicine (Visit 1) in that same group. Tertiary Hypothesis: Through administering a one-time dose of midodrine, the medicine-induced decreased blood flow to the skin will lessen the decline in Tcore and prevent or delay the associated decline in cognitive performance compared to the changes in Tcore and cognitive performance during cool temperature exposure without midodrine in the same group with tetraplegia.
The ability to maintain normal body core temperature (Tcore = 98.6°F) is impaired in persons with tetraplegia. Despite the known challenges to the ability of persons with spinal cord injury (SCI) to maintain Tcore, and the effects of hypothermia to impair mental function in able-bodied (AB) persons, there has been no work to date addressing these issues in persons with tetraplegia. The aim of this study is to determine if exposure of up to 2 hrs to cool temperatures (64°F) causes body core temperature to decrease in persons with tetraplegia and if that decrease is related to a decrease in mental performance. After sitting in a cool (64°F) room for up to 2 hours the investigators hypotheses are: Hypotheses (1): Tcore of most of the persons with tetraplegia will decline approximately 1.8°F (e.g., 98.6 to 96.8°F) while Tcore of controls will not decline at all; (2) Most of the persons with tetraplegia will show a decline in mental performance (memory or clear-headedness) while only some of AB controls will show a decline. The second aim of this study is to determine if a 10 mg dose of an approved blood pressure raising medicine (midodrine hydrochloride) will (1) reduce the decrease in body core temperature and (2) prevent or delay the decline in mental performance in the group with tetraplegia compared to the exact same procedures performed on the day with no medicine (Visit 1) in the same group. Hypotheses (3 \& 4): The changes in blood flow to the skin caused by taking a one-time dose of midodrine will lessen the decline in Tcore and prevent or delay the decline in mental performance compared to the changes in Tcore and mental performance during cool temperature exposure without midodrine in the group with tetraplegia.
Routine sleep duration varies greatly among individuals. The biological meaning of this variation is unknown. The term circadian rhythm refers to the biological clock that regulates the timing of falling asleep, waking up, and secretion of hormones, like melatonin. Melatonin is secreted at night. Previous studies have shown that melatonin may play a role in the regulation of sleep. The purpose of this study is to learn whether the duration of nighttime (nocturnal) melatonin secretion is longer in people with long regular sleep duration than people with short sleep duration. Researchers will compare levels of melatonin and cortisol, body temperature, sleepiness, and sleep in two extreme groups. Group one will be made up of people with short sleep duration lasting less than 6 hours. Group two will be made up of people with long sleep duration lasting more than 9 hours.