Task Progress:
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Aim #1: Develop a numerical model to estimate changes in intracranial venous flow, volume, compliance, and pressure in response to a fluid shift and changes in hydrostatic gradients. Include tissue compressive forces in the model. During this reporting period, we advanced and expanded the numerical model. We introduced collapsible vessels, which allow behavior such as body-orientation-dependent flow shunting in the jugular veins (i.e., jugular vein collapse in the upright position) to be modeled. We also used transmural pressure across the boundaries of model components (e.g., vessels and fluid cavities) to capture the effects of tissue weights and the resulting gravity dependent impact on the circulatory and CSF systems. Finally, we targeted integration of the circulatory and CSF sub-models, providing mass and pressure communications between the two sub-models.
Aim #2: Determine the cranial venous changes produced by fluid shifts and altered hydrostatic gradients. Use interventions that can produce fluid shifts (lower body negative pressure and lower body positive pressure) and alter hydrostatic gradients (supine and prone postures). These experiments are designed to provide data for validating and verifying the model developed as a part of Aim #1. The main efforts this reporting period were to design and test the MRI-compatible LBNP/LBPP (lower body negative pressure/lower body positive pressure) chamber, test the MRI imaging protocols, and develop the MRI data analysis tools needed for the studies. We also conducted a posture experiment with 10 subjects and determined that ocular measures plateau after an average of 12 minutes upon entering a new posture (e.g., seating, supine, prone). This will be used to ensure consistent data for all subjects in the MRI studies. The MRI-compatible LBNP/LBPP chamber will be employed it in the test campaign during the next reporting period. The optimal parameters for collecting and analyzing MRI data were established, which involved examine the trade off between scan accuracy, data needed for the model, and subject acceptability. We developed tools to aid hypothesis development of the etiology behind visual changes in long duration space flight. We developed graphical descriptions of the potential mechanisms for the microgravity-induced ocular and visual changes. We have acquired several devices to measure key parameters, such as an anterior segment module, episcleral venous pressure device, and a BIOPAC continuous, noninvasive blood pressure system. The data collected from these devices will be use to provide additional information for the model.
Aim #3: Identify individuals with common intracranial venous variants, and study them using the protocol outlined in Aim #2. Aim 3 is an objective for our third year. The data collection methods have been established in this reporting period through our Aim 2 objectives. In our initial cohort of pilot subjects, we have identified subjects with anatomical variants, the primary interest of this aim.
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Abstracts for Journals and Proceedings
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Anderson A, Fellows A, Buckey J. "Feasibility of dpoae mapping as an in-flight measure of intracranial pressure in space." 2015 NASA Human Research Program Investigators’ Workshop, Galveston, TX, January 13-15, 2015. 2015 NASA Human Research Program Investigators’ Workshop, Galveston, TX, January 13-15, 2015. , Jan-2015
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Abstracts for Journals and Proceedings
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Anderson A, Fellows A, Babu G, Swan J, Phillips S, Kattamis N, Knaus D, Zegans M, Buckey J. "Ocular and cerebrovascular changes in microgravity." 86th Scientific Meeting of the Aerospace Medical Association, Lake Buena Vista, Florida, May 10-14, 2015. 86th Scientific Meeting of the Aerospace Medical Association, Lake Buena Vista, Florida, May 10-14, 2015. , May-2015
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Abstracts for Journals and Proceedings
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Swan JG, Phillips SD, Kattamis N, Knaus DA, Zegans ME, Fellows AM, Buckey JC. "Effect of posture and microgravity on the eye and cranial vascular system." 2015 NASA Human Research Program Investigators’ Workshop, Galveston, TX, January 13-15, 2015. 2015 NASA Human Research Program Investigators’ Workshop, Galveston, TX, January 13-15, 2015. , Jan-2015
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Abstracts for Journals and Proceedings
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Phillips SD, Chepko A, Kattamis NT, Knaus DA, Swan JG, Zegans M, Buckey JC. "Modeling gravity dependence in the cranial venous circulatory system." 2015 NASA Human Research Program Investigators’ Workshop, Galveston, TX, January 13-15, 2015. 2015 NASA Human Research Program Investigators’ Workshop, Galveston, TX, January 13-15, 2015. , Jan-2015
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Abstracts for Journals and Proceedings
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Phillips S, Kattamis N, Chepko AB, Knaus DA, Swan JG, Zegans ME, Buckey JC. "Modeling the ocular and cerebrovascular changes in microgravity." 86th Scientific Meeting of the Aerospace Medical Association, Lake Buena Vista, Florida, May 10-14, 2015. 86th Scientific Meeting of the Aerospace Medical Association, Lake Buena Vista, Florida, May 10-14, 2015. , May-2015
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Awards
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Anderson A. "NSBRI First Award Fellowship, October 2015." Oct-2015
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