Clinical Research Directory

The Kidney's Response to Exercise in Heat, and the Impact of Vitamin B3 on This Response

The goal of this clinical trial is to learn about the processes occurring in the kidneys while under heat stress in healthy volunteers. The main questions it aims to answer are: * How do the chemicals produced by the body change under conditions of higher versus lower heat stress? * What role does a specific area of the body's metabolism, known as NAD+ metabolism, play in the body's response to heat stress, and can this response be modified by taking vitamin B3?

Beat the Heat Boston

The goal of this stepped wedge trial is to assess the practical effects of air conditioners on hot weather impacts among older adults. The main questions it aims to answer are: How does the presence of an air conditioning unit affect heat stress, heat strain, mental health, and healthcare utilization among older adults who did not previously have access to air conditioning? How, and in what conditioners, do older adults use air conditioning once it is installed in their home? Researchers will compare participants in arms with (A) and without (B) air conditioning units in the first summer season; this will allow them to assess the effect of air conditioners. In the second summer season, both arms will have air conditioning units, but those in the year two distribution arm (B) will receive an electricity subsidy, while those in the year one AC distribution arm (A) will not, allowing researchers to assess the effect of an electricity subsidy. Participants will be randomized to receive an air conditioner and financial support for electricity costs in either the first summer season or the second summer season of the study. * Heat stress, heat strain, mental health, and healthcare utilization will be assessed via participant survey. * Air conditioner utilization will be assessed via continuous load monitoring devices. * Indoor air temperature will be assessed via continuous data loggers.

Biological Impacts of Rising Temperatures on Maternal, Fetal, and Newborn Health: A Cohort Study (BIRTH Cohort)

The goal of this study is to learn how being exposed to high environmental temperatures during pregnancy affects the health of pregnant women and their babies. The study also aims to understand how the body responds to heat stress during pregnancy and how this might lead to pregnancy complications and birth problems like early birth or low birth weight. The main questions that the study aims to answer are: 1. What are the acute and chronic effects of environmental heat exposure on pregnancy and birth outcomes across different trimesters? 2. Through which biological pathways does heat stress impact maternal, fetal, and infant health across varying gestational ages? 3. How do socio-demographic factors, maternal characteristics, and nutritional status of women modify the relationship between environmental heat exposure and adverse pregnancy outcomes? The study will take place in rural parts of Sindh, Pakistan. These areas often experience extreme heat and have limited access to electricity or cooling systems like fans or air conditioners. This study will include pregnant women who are in their first trimester (under 14 weeks of pregnancy). Before starting any study activities, researchers will explain the study to each woman in a language she understands and ask for her written permission to take part (informed consent). At the beginning of the study, participants will visit a study clinic. During this visit, researchers will check their height and weight, perform an ultrasound, and collect a small amount of blood for testing. Participants will also be asked to wear a small device that measures the air temperature and humidity in their surroundings. The researchers will follow each participant during her pregnancy, with visits during the second and third trimesters at the study clinic. At each visit, researchers will check how much heat the participant has been exposed to using the data from the device and from her own answers to a simple questionnaire. The questionnaire will have questions about their heat exposure at work, home, type of clothing, and how they deal with hot weather. Serial ultrasound, blood and urine tests will be conducted so researchers can study signs of stress, hydration, and other changes in the body. A smaller group of participants will also wear a device to measure their body skin temperature, heart rate, physical activity and sleep during pregnancy. When the baby is born, researchers will collect information about the birth, including the baby's weight and length, the time of delivery, and whether there were any complications during birth. After delivery, both the mother and baby will be followed for up to 12 months. During this time, the research team will check the health of both the mother and baby and see how heat exposure during pregnancy may affect the baby's growth over time. At delivery, placental weight and volume will be collected for a smaller group of women. Breastmilk sampling will also be done for this group of women to understand the effect of high temperatures on breastmilk quality. This study does not involve any treatment or medicine. Instead, researchers will observe the participants to learn how real-life heat exposure affects them during pregnancy. The findings from this study may help public health officials and governments find better ways to protect pregnant women and babies from the harmful effects of climate change and extreme heat, especially in places with limited resources.

Effect of Exercise and Heat Stress on Acute Cardiometabolic Adaptations in Healthy Young Adults

Life in space is completely void of physical and environmental stress. It is well known that living things need regular physical stress (e.g. exercise) to remain strong, functional and healthy. More and more research is showing that regular environmental stress, for example heat and hypoxia, can further improve physical health. Astronauts aboard the international space station (ISS) exercise for 1-2 hours every day to avoid physical deconditioning that would otherwise cause them to age rapidly in space. Although physical exercise is very effective in remedying this deconditioning, today's astronauts still have physiological changes that indicate accelerated aging. This is a cause for concern given NASA's priority to travel to mars within the next decade; a mission that will require at least double the duration in space for our astronauts. The investigators think that the complete absence of environmental stress, i.e., heat, may be contributing to the accelerated aging that occurs during spaceflight. Our study will assess the health effects of adding heat stress to exercise that could be performed in space by astronauts. The goal is to inform best practice for astronauts to avoid physical deconditioning during long-duration spaceflight. This information will also be relevant to life on earth as spaceflight is a model of inactivity here on earth. Therefore, the potential benefits of adding heat stress will likely translate to life in space and on earth.

Impact of Extreme Heat on Myocardial Blood Flow and Flow Reserve in Young and Older Adults

Extreme heat causes a disproportionate number of hospitalizations and deaths in older adults relative to any other age group. Importantly, many hospitalizations and deaths are primarily due to cardiovascular events such as myocardial infarction. Previous data indicate that older adults have attenuated skin blood flow and sweating responses when exposed to heat, resulting greater increase in core body temperature. Despite these observations, relatively little is known about the risk for myocardial ischemia potentially contributing to the aforementioned higher morbidity and mortality in older adults during heat waves. The broad objective of this work is to determine the impact of ambient heat exposure on myocardial blood flow and flow reserve in young and older adults. Aim 1 will test the hypothesis that older adults exhibit attenuated myocardial flow reserve compared to young adults during heat stress. Aim 2 will determine if the percent of maximal myocardial flow reserve (assess via vasodilator stress) during heat exposure is higher in older adults compared to young adults. The expected outcome from this body of work will improve our understanding of the consequences of aging on cardiovascular responses to ambient heat stress.