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Project Title:  Mechanical and Gravitational Countermeasures to Ocular Changes During Strict Head-Down Tilt Bedrest (PI: Macias) Reduce
Images: icon  Fiscal Year: FY 2023 
Division: Human Research 
Research Discipline/Element:
HRP HHC:Human Health Countermeasures
Start Date: 08/26/2022  
End Date: 08/20/2024  
Task Last Updated: 08/30/2022 
Download report in PDF pdf
Principal Investigator/Affiliation:   Macias, Brandon  Ph.D. / NASA Johnson Space Center 
Address:  Johnson Space Center Cardiovascular and Vision Laboratory 
2101 NASA Parkway, HAC/B21N-1207 
Houston , TX 77058 
Email: brandon.r.macias@nasa.gov 
Phone: 281-483-2026  
Congressional District: 36 
Web:  
Organization Type: NASA CENTER 
Organization Name: NASA Johnson Space Center 
Joint Agency:  
Comments: NOTE: Became civil servant fall 2020; previously KBR/NASA Johnson Space Center. Prior to that until 2016, was at the University of California, San Diego. 
Co-Investigator(s)
Affiliation: 
Brunstetter, Tyson  O.D., Ph.D. NASA Johnson Space Center 
Huang, Alex  M.D., Ph.D. Doheny Eye Institute 
Kramer, Larry  M.D. University of Texas Health Science Center at Houston 
Laurie, Steven  Ph.D. KBR/NASA Johnson Space Center 
Lee, Stuart  Ph.D. KBR/NASA Johnson Space Center 
Lovering, Andrew  Ph.D. University of Oregon 
Martin, Bryn  Ph.D. Alcyone Therapeutics Inc. 
Young, Millennia  Ph.D. NASA Johnson Space Center 
Lytle, Jason  KBR/NASA Johnson Space Center 
Pardon, Laura  KBR/NASA Johnson Space Center 
Key Personnel Changes / Previous PI: August 2022 report: Scott Greenwald, Ph.D. has left NASA and is no longer with the project (Ed., 8/29/22). June 2022 report: CoInvestigators Alan Hargens, Jessica Jasien, and Benjamin Levine are no longer with the project (Ed., 7/22/22).
Project Information: Grant/Contract No. Directed Research 
Responsible Center: NASA JSC 
Grant Monitor: Stenger, Michael  
Center Contact: 281-483-1311 
michael.b.stenger@nasa.gov 
Solicitation / Funding Source: Directed Research 
Grant/Contract No.: Directed Research 
Project Type: GROUND 
Flight Program:  
TechPort: No 
No. of Post Docs:  
No. of PhD Candidates:  
No. of Master's Candidates:  
No. of Bachelor's Candidates:  
No. of PhD Degrees:  
No. of Master's Degrees:  
No. of Bachelor's Degrees:  
Human Research Program Elements: (1) HHC:Human Health Countermeasures
Human Research Program Risks: (1) SANS:Risk of Spaceflight Associated Neuro-ocular Syndrome (IRP Rev I)
Human Research Program Gaps: (1) SANS-302:Test mechanical countermeasures in a strict bed rest analog (IRP Rev L)
(2) SANS-401:Test non-mechanical countermeasures in a strict bed rest analog (IRP Rev L)
Flight Assignment/Project Notes: NOTE: Project start date updated due to P.I. change to B. Macias. Information per C. Ribeiro/NASA-JSC. (Ed. 8/29/22).

Task Description: The Spaceflight Associated Neuro-ocular Syndrome (SANS) is associated with structural and functional ocular and brain changes and develops in ~2/3rds of astronauts during long-duration spaceflight. Although the etiology of SANS is unknown, a weightlessness-driven headward fluid redistribution relative to the upright position on Earth is hypothesized to be a primary initiating factor. A countermeasure that can successfully reverse this headward fluid shift for multiple hours per day may be needed to prevent SANS. Exposure to 30 days of the spaceflight analog strict 6 degree head-down tilt (HDT) bedrest induces the development of optic disc edema, a hallmark sign of SANS, in 2/3 of subjects; thus, NASA will utilize this platform to test the effectiveness of various countermeasures to prevent or reduce the development of SANS findings. This study will include a control group exposed to 30 days of strict 6 degree HDT. A second group of subjects will be exposed to 6 hours of 25 mmHg lower body negative pressure (LBNP), daily, during 30 days of strict 6 degree HDT bedrest. A third group of subjects will be exposed to 6 hours of upright posture per day, and 6 degree HDT for the remaining 18 h/day. This will help determine if daily exposure to 6 hours total of upright posture, fully reversing the headward fluid for the same duration of use as the LBNP group, is sufficient to prevent SANS findings, and thus can direct future countermeasure studies with respect to the duration needed to successfully prevent SANS. We will assess multiple cerebral, vascular, and ocular outcome measures to determine the effects of 30 days strict 6 degree HDT bedrest, and the ability of daily 6 hour exposure to LBNP or upright positioning to prevent these changes.

Specific Aims:

1. To determine if daily exposure to actual (upright posture) and simulated (LBNP) hydrostatic pressure gradients prevents ocular and cerebral structural changes during 30 days of strict 6° head-down tilt bedrest.

2. To determine if daily exposure to actual (upright posture) and simulated (LBNP) hydrostatic pressure gradients prevents ocular functional changes during 30 days of strict 6° head-down tilt bedrest.

3. To determine if daily exposure to actual (upright posture) and simulated (LBNP) hydrostatic pressure gradients prevents vascular and cerebrospinal fluid changes during 30 days of strict 6° head-down tilt bedrest.

This bedrest study will be implemented in the :envihab facility at the German Aerospace Center (DLR) in Cologne, Germany.

Research Impact/Earth Benefits:

Task Progress & Bibliography Information FY2023 
Task Progress: Continuation of " Mechanical and Gravitational Countermeasures to Ocular Changes During Strict Head-Down Tilt Bedrest" with Dr. Macias as new Principal Investigator (PI). Former PI was Dr. Marshall-Goebel.

Bibliography Type: Description: (Last Updated: 04/12/2022) 

Show Cumulative Bibliography Listing
 
 None in FY 2023