| Autor: |
Kramer LA; Department of Diagnostic Imaging and Intervention, McGovern Medical School, UTHealth Houston, Houston, Texas, United States., Hasan KM; Department of Diagnostic Imaging and Intervention, McGovern Medical School, UTHealth Houston, Houston, Texas, United States., Zhang X; Center for Clinical and Translational Sciences, McGovern Medical School, UTHealth Houston, Houston, Texas, United States., Mulder E; Research, Relationships and Development, Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany., Gerlach DA; Cardiovascular Aerospace Medicine, Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany., Marshall-Goebel K; Biomedical Research and Environmental Sciences Division, NASA Johnson Space Center, Houston, Texas, United States., Macias BR; Cardiovascular and Vision Laboratory, NASA Johnson Space Center, Houston, Texas, United States., Laurie SS; Cardiovascular and Vision Laboratory, Kellogg, Brown and Root, Houston, Texas, United States., Strangman G; Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States., Iyer R; Department of Diagnostic Imaging and Intervention, McGovern Medical School, UTHealth Houston, Houston, Texas, United States., Bershad EM; Department of Neurology and Neurosurgery, Baylor College of Medicine, Houston, Texas, United States. |
| Abstrakt: |
Long-duration spaceflight is associated with pathophysiological changes in the intracranial compartment hypothetically linked to microgravity-induced headward fluid shift. This study aimed to determine whether daily artificial gravity (AG) sessions can mitigate these effects, supporting its application as a countermeasure to spaceflight. Twenty-four healthy adult volunteers (16 men) were exposed to 60 days of 6° head-down tilt bed rest (HDTBR) as a ground-based analog of chronic headward fluid shift. Subjects were divided equally into three groups: no AG (control), daily 30-min intermittent AG (iAG), and daily 30-min continuous (cAG). Internal carotid artery (ICA) stroke volume (ICA SV ), ICA resistive index (ICA RI ), ICA flow rate (ICA FR ), aqueductal cerebral spinal fluid flow velocity (CSF V ), and intracranial volumetrics were quantified at 3 T. MRI was performed at baseline, 14 and 52 days into HDTBR, and 3 days after HDTBR (recovery). A mixed model approach was used with intervention and time as the fixed effect factors and the subject as the random effect factor. Compared with baseline, HDTBR was characterized by expansion of lateral ventricular, white matter, gray matter, and brain + total intracranial cerebral spinal fluid volumes, increased CSFv, decreased ICA SV , and decreased ICA FR by 52 days into HBTBR (All P s < 0.05). ICA RI was only increased 14 days into HDTBR ( P < 0.05). Neither iAG nor cAG significantly affected measurements compared with HDTBR alone, indicating that 30 min of daily exposure was insufficient to mitigate the intracranial effects of headward fluid shift. Greater AG session exposure time, gravitational force, or both are suggested for future countermeasure research. NEW & NOTEWORTHY Brief exposure to continuous or intermittent artificial gravity via short-arm centrifugation was insufficient in mitigating the intracranial pathophysiological effects of the headward fluid shift simulated during head-down tilt bed rest (HDTBR). Our results suggest that greater centrifugation session duration, gravitational force, or both may be required to prevent the development of spaceflight-associated neuro-ocular syndrome and should be considered in future ground-based countermeasure studies. |
