This is a randomized controlled human exposure crossover study. Investigators aims to assess the acute effects of low temperature exposure and the underlying mechanisms.
The investigators will conduct a randomized controlled human exposure crossover study among about 50 healthy young adults in Shanghai, China. Each subject will be exposed twice: once to the low temperature (16#) and once to the moderate temperature (22#) in a chamber for about 2-2.5 hours. During the exposure session, each subject will be requested to rest. Health examinations will be conducted immediately prior to exposure (within 1 hour before the exposure session), during the period of exposure, and after exposure (within 2 hours after the exposure session). Health examinations include spirometry, Holter monitoring, blood pressure tests, cognitive function tests, symptom questionnaires, and magnetic resonance imaging. Investigators plan to collect blood, urine, exhaled breath condensate, and oropharyngeal swabs samples.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
SINGLE
Enrollment
50
The exposure group will be exposed to low temperature (16#) in a chamber for about 2 hours, resting during the whole periods.
The exposure group will be exposed to thermoneutral temperature (22#) in a chamber for about 2 hours, resting during the whole periods.
Department of Environmental Health, School of Public Health, Fudan University
Shanghai, Shanghai Municipality, China
Heart Rate Variability Parameters
Investigators plan to measure heart rate variability (HRV) parameters (e.g., SDNN, PNN50, LF, HF)
Time frame: Volunteers will be asked to wear electrographic Holter monitors for 24 hours from 1:00 P.M. at the day of intervention to 1:00 P.M. at the next day.
Blood Pressure
The changes of systolic blood pressure (SBP) and diastolic blood pressure (DBP) will be measured.
Time frame: Blood pressure will be examined before exposure and immediately after the exposure session
Forced vital capacity
Investigators plan to measure forced vital capacity (FVC) by spirometry
Time frame: Lung function will be examined before exposure and half an hour after the exposure session
Forced expiratory volume in one second
Investigators plan to measure forced expiratory volume in one second (FEV1) by spirometry.
Time frame: Lung function will be examined before exposure and half an hour after the exposure session
Maximal mid-expiratory flow
Investigators plan to measure maximal mid-expiratory flow (MMEF) by spirometry.
Time frame: Lung function will be examined before exposure and half an hour after the exposure session
Results of Stroop Tests
Investigators plan to measure the changes of cognitive function using Stroop Test.
Time frame: The tests will be conducted before exposure and immediately after the exposure session
Changes of skin temperature
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The changes of wrist skin temperature will be measured
Time frame: Skin temperature will be examined from 1:00 P.M. to 4:30 P.M. at the day of intervention
Results of simple reaction time
Investigators plan to measure the changes of cognitive function using visual simple reaction time test.
Time frame: Simple reaction time will be examined before exposure and immediately after the exposure session
Results of visual memory
Investigators plan to measure the changes of cognitive function using visual memory test. Every level, a number of tiles will flash white. The participants will be required to memorize them, and pick them again after the tiles are reset. Higher levels refer to better visual memory.
Time frame: Visual memory will be examined before exposure and immediately after the exposure session
Activated brain regions demonstrating brain activity related to the low temperature exposure
Investigators plan to conduct magnetic resonance imaging (MRI) after exposure. The MRI data will be processed through Data Processing and Analysis for Brain Imaging (DPABI) sofrware to obtain brain activity parameters, such as fractional amplitude of low-frequency fluctuation (fALFF). Brain regions that change after exposure between the two groups would be further idenfitied.
Time frame: MRI will be examined 1 hour after the exposure session
Changes in cerebral hemodynamics demonstrating brain activity related to the low temperature exposure
Investigators plan to conduct functional near-infrared spectroscopy (fNIRS) to measure the changes in oxygenated hemoglobin and deoxygenated hemoglobin after exposure. Matlab would be applied to process data and evaluate the changes in cerebral hemodynamics associated with low temperature exposure
Time frame: fNIRS will be examined before exposure and immediately after the exposure session